1. What is the difference between scavenging and supercharging?
Ans: Scavenging is a process of flushing out burnt gases from the engine cylinder by introducing fresh air in the
cylinder before exhaust stroke ends. Supercharging is the process of supplying a higher mass of air by compressing
the atmospheric air.
2. What are the names given to constant temperature, constant pressure, constant volume, constant internal
energy, constant enthalpy, and constant entropy processes.
Ans: Isothermal, isochronic, isobaric, free expression, throttling, and adiabatic processes respectively.
3. In a Rankine cycle if maximum steam pressure is increased keeping steam temperature and condenser pressure
the same, what will happen to dryness fraction of steam after expansion? Ans: It will decrease.
4. Why entropy change for a reversible adiabatic process is zero?
Ans: Because there is no heat transfer in this process.
5. What are the two essential conditions of perfect gas?
Ans: It satisfies the equation of state and its specific heats are constant.
6. Enthalpy and entropy are functions of one single parameter. Which is that?
Ans: Temperature.
7. Why the rate of condensation is higher on a polished surface compared to the rusty surface?
Ans: Polished surface promotes dropwise condensation and does not wet the surface.
8. How much resistance is offered to heat flow by drop wise condensation?
Ans: Nil
How are these questions – please do add comments and if you like them please do share this post on Facebook,
Linkedin, twitter, and google plus.
9. What is the relationship between the COP of heating and cooling?
Ans: COP of heating is one(unity) more than COP of cooling.
10. How much is the work done in the isochoric process?
Ans: Zero.
11. When the maximum discharge is obtained in nozzle?
Ans: At the critical pressure ratio.
12. Under what condition the work is done in the reciprocating compressor will be least?
Ans: It is least when the compression process approaches isothermal. For this purpose, attempts are made to cool the
air during compression.
This document contains interview questions for mechanical engineering (ME) students regarding thermodynamics. Some of the key questions asked relate to:
- When a real gas behaves like an ideal gas
- The significance of entropy in relation to the second law of thermodynamics
- The differences between heat transfer and thermodynamics
- Why thermal radiation can never reach absolute zero temperature
- The differences between a pipe and a tube
- The differences between a flywheel and governor
- The differences between tempering and annealing
- The principle of mechanical refrigeration relying on a volatile liquid absorbing heat through boiling
This document discusses combustion and fuel characteristics in internal combustion engines. It covers topics such as combustion process terms like normal combustion and abnormal combustion. It also discusses spark knock, surface ignition, ignition delay, combustion requirements, air-fuel ratios, ignition timing, and advance timing. The goal is to understand the combustion process in spark ignition and compression ignition engines as well as the phenomenon of knocking.
A century and nearly two decades later there has been immense progress in the field of IC engines, though many phenomenon taking place are still to be understood physically. This blog aims at comprehension of some of the astonishing research that has been done in this field restricting our interest to combustion with some amusing facts.
5.2 combustion and combustion chamber for si enginesFasilMelese
The document discusses combustion and combustion chambers in spark ignition engines. It describes the conditions needed for combustion, the different types of fuel-air mixtures, and the stages of combustion in a homogeneous mixture. The three stages of actual engine combustion are the delay period, flame propagation, and wall quenching. Factors that influence flame speed like turbulence, fuel-air ratio, temperature and pressure are also summarized. Abnormal combustion phenomena of knock and surface ignition are described along with causes of end gas combustion and the effects of various engine variables on knocking.
Combustion in diesel engines occurs in three phases: 1) the ignition delay phase, 2) the premixed combustion phase, and 3) the mixing-controlled combustion phase. The ignition delay phase determines the rate of pressure rise and peak pressure/temperature, affecting noise and NOx emissions. Premixed combustion involves fuel-air mixtures at the stoichiometric ratio, producing high pressure/temperature rises and NOx. Mixing-controlled combustion depends on fuel-air mixing rates, with combustion along rich, stoichiometric, and lean paths. Heat release rate diagrams show an initial high rate corresponding to the premixed phase, followed by a gradually decreasing rate in the main release period.
The document discusses steam generators and boiler systems. It covers:
1. Steam generators are used to generate steam at desired rates, pressures, and temperatures for use in power plants. They use fuel combustion to heat water into steam.
2. Boiler systems comprise feedwater, steam, and fuel systems. Boilers are enclosed vessels that transfer combustion heat to water to produce heated water or steam for industrial processes.
3. There are two main types of boilers - fire tube and water tube. Fire tube boilers have combustion gases passing through tubes surrounded by water. Water tube boilers reverse this configuration.
1. Combustion involves the rapid chemical combination of fuel and oxygen, resulting in heat release. It requires a combustible mixture, an ignition source, and flame propagation.
2. In spark ignition (SI) engines, a carburetor supplies an air-fuel mixture and a spark plug ignites it. Combustion in SI engines occurs in three stages: ignition lag, flame propagation, and afterburning.
3. Factors like air-fuel ratio, compression ratio, load, turbulence, and engine speed affect the flame propagation rate in SI engines. Higher propagation speeds improve efficiency and fuel economy.
The document discusses combustion in internal combustion engines. It covers:
1) The normal combustion process in spark ignition engines including the 3 stages of combustion and factors affecting flame speed.
2) The combustion process in compression ignition engines including the 4 stages and factors affecting the ignition delay period.
3) Abnormal combustion phenomena like knock and types of abnormal combustion in diesel engines.
This document contains interview questions for mechanical engineering (ME) students regarding thermodynamics. Some of the key questions asked relate to:
- When a real gas behaves like an ideal gas
- The significance of entropy in relation to the second law of thermodynamics
- The differences between heat transfer and thermodynamics
- Why thermal radiation can never reach absolute zero temperature
- The differences between a pipe and a tube
- The differences between a flywheel and governor
- The differences between tempering and annealing
- The principle of mechanical refrigeration relying on a volatile liquid absorbing heat through boiling
This document discusses combustion and fuel characteristics in internal combustion engines. It covers topics such as combustion process terms like normal combustion and abnormal combustion. It also discusses spark knock, surface ignition, ignition delay, combustion requirements, air-fuel ratios, ignition timing, and advance timing. The goal is to understand the combustion process in spark ignition and compression ignition engines as well as the phenomenon of knocking.
A century and nearly two decades later there has been immense progress in the field of IC engines, though many phenomenon taking place are still to be understood physically. This blog aims at comprehension of some of the astonishing research that has been done in this field restricting our interest to combustion with some amusing facts.
5.2 combustion and combustion chamber for si enginesFasilMelese
The document discusses combustion and combustion chambers in spark ignition engines. It describes the conditions needed for combustion, the different types of fuel-air mixtures, and the stages of combustion in a homogeneous mixture. The three stages of actual engine combustion are the delay period, flame propagation, and wall quenching. Factors that influence flame speed like turbulence, fuel-air ratio, temperature and pressure are also summarized. Abnormal combustion phenomena of knock and surface ignition are described along with causes of end gas combustion and the effects of various engine variables on knocking.
Combustion in diesel engines occurs in three phases: 1) the ignition delay phase, 2) the premixed combustion phase, and 3) the mixing-controlled combustion phase. The ignition delay phase determines the rate of pressure rise and peak pressure/temperature, affecting noise and NOx emissions. Premixed combustion involves fuel-air mixtures at the stoichiometric ratio, producing high pressure/temperature rises and NOx. Mixing-controlled combustion depends on fuel-air mixing rates, with combustion along rich, stoichiometric, and lean paths. Heat release rate diagrams show an initial high rate corresponding to the premixed phase, followed by a gradually decreasing rate in the main release period.
The document discusses steam generators and boiler systems. It covers:
1. Steam generators are used to generate steam at desired rates, pressures, and temperatures for use in power plants. They use fuel combustion to heat water into steam.
2. Boiler systems comprise feedwater, steam, and fuel systems. Boilers are enclosed vessels that transfer combustion heat to water to produce heated water or steam for industrial processes.
3. There are two main types of boilers - fire tube and water tube. Fire tube boilers have combustion gases passing through tubes surrounded by water. Water tube boilers reverse this configuration.
1. Combustion involves the rapid chemical combination of fuel and oxygen, resulting in heat release. It requires a combustible mixture, an ignition source, and flame propagation.
2. In spark ignition (SI) engines, a carburetor supplies an air-fuel mixture and a spark plug ignites it. Combustion in SI engines occurs in three stages: ignition lag, flame propagation, and afterburning.
3. Factors like air-fuel ratio, compression ratio, load, turbulence, and engine speed affect the flame propagation rate in SI engines. Higher propagation speeds improve efficiency and fuel economy.
The document discusses combustion in internal combustion engines. It covers:
1) The normal combustion process in spark ignition engines including the 3 stages of combustion and factors affecting flame speed.
2) The combustion process in compression ignition engines including the 4 stages and factors affecting the ignition delay period.
3) Abnormal combustion phenomena like knock and types of abnormal combustion in diesel engines.
Detonation occurs when the combustion process moves too quickly in an engine cylinder, causing abnormally high pressure and temperatures. This happens if fuel ignites before the scheduled ignition of the spark plug. Detonation can damage engine components and is caused by factors like improper ignition timing, a lean air-fuel mixture, low octane fuel, and high exhaust back pressure. Engines can be protected from detonation by using higher octane fuel, retarding the ignition timing, cooling the air charge, and ensuring a proper fuel supply. Pre-ignition is a related issue where the fuel ignites prematurely due to hot spots in the combustion chamber rather than the spark plug.
5+ combustion and combustion chamber for si enginesFasilMelese
Combustion in spark ignition engines can occur via homogeneous or heterogeneous mixtures. In a homogeneous mixture, combustion occurs in three stages: an initial delay period, a flame propagation period where pressure rises rapidly, and a final quenching period. Factors that influence the flame speed include turbulence, fuel-air ratio, temperature/pressure, compression ratio, engine output, and engine speed. Abnormal combustion in the form of knock or surface ignition can damage the engine and cause noise. Knock occurs when end gases autoignite, while surface ignition initiates at hot spots. Various engine variables like temperature, compression ratio, and spark timing can affect knocking.
The document discusses the design requirements of combustion chambers in spark ignition engines. It states that good combustion chambers aim to provide high power output, efficiency, smooth operation and low emissions. Key design considerations include high compression ratios, turbulence, compact size, and valve and spark plug placement. Historically, T-head, L-head, and I-head (overhead valve) designs have been used, with overhead valve becoming prevalent for its performance at high compression ratios. Modern combustion chamber designs include bath tub and wedge types within cylinder heads.
The document discusses the combustion process in diesel engines. It describes the four stages of combustion: 1) ignition delay, 2) rapid uncontrolled combustion, 3) lower rate combustion, and 4) tail of combustion. It also discusses knocking in diesel engines, the rating of diesel fuels using metrics like cetane number and diesel index, and the relationship between cetane number and octane number. The critical compression ratio is defined as the minimum ratio needed for ignition under specified conditions.
This document discusses steam systems used in industrial processes. It provides information on:
- The properties of steam including enthalpy, saturation temperature, and phase diagrams.
- Components of steam distribution systems including piping, drainage, expansion, and insulation.
- Methods for sizing steam pipes to minimize pressure drop and optimize energy efficiency.
- The importance of proper steam trapping to remove condensate and maintain dry steam.
Combustion in an SI engine occurs in three stages:
1. The ignition lag stage is the delay between the spark and noticeable pressure rise from combustion. This allows the fuel-air mixture to heat up to its self-ignition temperature.
2. In the flame propagation stage, the flame front travels across the combustion chamber, releasing energy and increasing pressure.
3. The afterburning stage finishes combusting any remaining unburnt fuel-air mixture after the flame front passes.
Download Link (Copy URL):
https://sites.google.com/view/varunpratapsingh/teaching-engagements
This PPT contained slides for Steam distribution system, which is a third unit in Energy Conservation subject of final year in Mechanical Engineering Branch.
The content of PPT are mentioned below:
Steam Distribution System, Thermodynamics, Heat, Properties of steam, steam, steam system, PDRS, Steam pipe installation, Dryers, Operation and maintenance of steam traps, Condensate Recovery System, Flash Recovery System, Energy Conservation Opportunity in Steam Distribution System.
Steam distribution system, utilization and designAzmir Latif Beg
n any steam plant or any process plant effectiveness of steam distribution system is dependent upon the project specific conditions like location and layout of the process plant and its steam consuming equipment like heat exchangers, decorators etc. Steam distribution circuit is one of the major link between the steam production point and the point of end use i.e. process plant. Primary steam generating source are co-generation plant and Steam generators. However it not the source of steam generation but the effective and efficient steam distribution system that decides right quality (pressure and temperature) and quantity of steam to reach to the process through it. Thus designing of steam distribution is to be given due importance along with installation and subsequently maintenance during operation.
High pressure steam leakage from the high pressure to intermediate pressure turbine causes several issues:
- It increases calculated heat rate and intermediate pressure efficiency while decreasing low pressure efficiency.
- It decreases the mass flow rate through the downstream high pressure turbine.
- It can lead to load curtailment to avoid overheating reheat tubes or issues with thrust balance and control of reheat temperature.
Seal damage from misalignment, poor start-ups, or water induction incidents can cause the high pressure steam leakage. Replacements or repairs of damaged components like seals, snout rings, and shell joints may be needed to address the leakage.
Two methods to estimate the leakage are the temperature variance method and blow down method which uses
A boiler or steam generator is a device used to create steam by applying heat energy to water. Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure.
Steam flooding is a method used to improve heavy oil recovery after waterflooding. There are two main types: cyclic steam stimulation which uses a single well for injection and production over cycles, and steam flooding which continuously injects steam into multiple injection wells to drive mobilized oil towards producers. As steam is injected, it forms distinct zones - a condensing zone, saturated steam zone, transition zone, and displacement zone. Heat from steam reduces oil viscosity and interfacial tension, altering wettability and improving displacement of oil towards producers. Optimal recovery involves infill drilling, waterflooding after breakthrough, using low quality steam, and foaming additives to reduce gravity override.
Knocking occurs due to spontaneous combustion of the remaining fuel-air mixture after normal combustion. It results in an uncontrolled combustion process that generates shock waves and excessive pressure and temperature. Knocking happens when there are two flame fronts inside the engine cylinder rather than a uniform propagation of a single flame front from top to bottom. Factors that can cause knocking include poor fuel quality, improper engine cooling, and suboptimal engine design parameters such as valve size and position of fuel injectors.
1. A steam generator or boiler is a closed vessel made of steel that transfers heat from fuel combustion to water to generate steam.
2. Boilers should be safe, accessible for maintenance, efficient in absorbing heat, simple in construction, and have low initial and maintenance costs.
3. There are many types of boilers classified by factors like the contents in tubes (fire tube or water tube), furnace position, and circulation method. Proper consideration of factors like steam needs, area, and costs is important for boiler selection.
The document discusses different types of boilers, including fire tube and water tube boilers. It also describes the basic model of ignition and flame propagation in boilers. Key points covered include the conditions needed to form a stable flame during coal combustion, and the processes of nucleate/convective boiling and film boiling that occur as heat is transferred to water in boiler walls. Departure from nucleate boiling is explained, along with how it can be avoided by increasing pressure, fluid flow rate, or using a lower temperature bulk fluid.
The combustion process in a compression ignition (CI) engine occurs differently than in a spark ignition engine. In a CI engine, the air-fuel mixture is not homogeneous since the liquid fuel remains in particle form. Combustion takes place simultaneously at many points as the liquid fuel is evaporated, mixed with air, and raised to its ignition temperature. There are four stages of combustion in a CI engine: 1) an ignition delay period as the fuel is injected and begins to chemically react, 2) a premixed burning phase of maximum heat release, 3) a mixing-controlled combustion phase where fuel burns as it is injected, and 4) a tail/afterburning region where remaining unburned fuel continues burning into the
The document discusses abnormal combustion in spark ignition engines. Under normal combustion, the flame travels uniformly across the combustion chamber. Abnormal combustion occurs when combustion deviates from this normal behavior. Two types of abnormal combustion are pre-ignition and knocking. Pre-ignition occurs when the fuel-air mixture ignites before the spark, while knocking is the auto-ignition of unburned fuel late in the combustion cycle. Both pre-ignition and knocking can damage engine components and reduce performance. The causes of abnormal combustion include issues with fuel quality, engine parts, air quality, cooling, vibration, and operating environment.
This document provides an introduction to steam generators and boilers. It discusses the origin and impact of steam on science and technology. It describes the working principles of fire tube and water tube boilers. The key components and classifications of boilers are explained. The document also covers boiler efficiency, capacity, pressure, mountings, accessories and their functions. High pressure boilers and their types are discussed. The fuels used for steam generation and the analysis and grading of coal are summarized. Finally, the necessity and requirements of an effective coal handling system are outlined.
The document discusses combustion in compression ignition (CI) engines. It describes the four stages of combustion in CI engines: (1) ignition delay period, (2) uncontrolled combustion, (3) controlled combustion, and (4) after burning. It explains that the ignition delay period allows fuel to accumulate, causing uncontrolled combustion and a steep pressure rise when ignition occurs. Controlled combustion then follows, where combustion is matched to the fuel injection rate.
Interview Questions for Mechanical Engineering StudentsMoredhvaj giri
This document contains answers to various mechanical engineering interview questions. Some key points covered include:
1. Entropy decreases with increasing temperature due to entropy being inversely proportional to temperature.
2. Different engine specifications and exhaust passages produce different sounds in bikes despite using SI engines.
3. One horsepower equals 746.2 watts of power.
The document provides concise explanations and definitions for common mechanical engineering concepts and terms asked during job interviews.
ME6301 ENGINEERING THERMODYNAMICS SHORT QUESTIONS AND ANSWERS - UNIT IIIBIBIN CHIDAMBARANATHAN
This document provides an overview of thermodynamics concepts related to properties of pure substances and steam power cycles. It includes definitions of key terms like enthalpy of steam, latent heat of evaporation, superheated steam, dryness fraction, and critical point. The document also summarizes the assumptions and components of the Rankine cycle, methods to improve its efficiency including reheating, and comparisons to other cycles like Carnot. Overall, the document serves as a study guide for engineering thermodynamics topics focusing on steam as the working fluid.
Detonation occurs when the combustion process moves too quickly in an engine cylinder, causing abnormally high pressure and temperatures. This happens if fuel ignites before the scheduled ignition of the spark plug. Detonation can damage engine components and is caused by factors like improper ignition timing, a lean air-fuel mixture, low octane fuel, and high exhaust back pressure. Engines can be protected from detonation by using higher octane fuel, retarding the ignition timing, cooling the air charge, and ensuring a proper fuel supply. Pre-ignition is a related issue where the fuel ignites prematurely due to hot spots in the combustion chamber rather than the spark plug.
5+ combustion and combustion chamber for si enginesFasilMelese
Combustion in spark ignition engines can occur via homogeneous or heterogeneous mixtures. In a homogeneous mixture, combustion occurs in three stages: an initial delay period, a flame propagation period where pressure rises rapidly, and a final quenching period. Factors that influence the flame speed include turbulence, fuel-air ratio, temperature/pressure, compression ratio, engine output, and engine speed. Abnormal combustion in the form of knock or surface ignition can damage the engine and cause noise. Knock occurs when end gases autoignite, while surface ignition initiates at hot spots. Various engine variables like temperature, compression ratio, and spark timing can affect knocking.
The document discusses the design requirements of combustion chambers in spark ignition engines. It states that good combustion chambers aim to provide high power output, efficiency, smooth operation and low emissions. Key design considerations include high compression ratios, turbulence, compact size, and valve and spark plug placement. Historically, T-head, L-head, and I-head (overhead valve) designs have been used, with overhead valve becoming prevalent for its performance at high compression ratios. Modern combustion chamber designs include bath tub and wedge types within cylinder heads.
The document discusses the combustion process in diesel engines. It describes the four stages of combustion: 1) ignition delay, 2) rapid uncontrolled combustion, 3) lower rate combustion, and 4) tail of combustion. It also discusses knocking in diesel engines, the rating of diesel fuels using metrics like cetane number and diesel index, and the relationship between cetane number and octane number. The critical compression ratio is defined as the minimum ratio needed for ignition under specified conditions.
This document discusses steam systems used in industrial processes. It provides information on:
- The properties of steam including enthalpy, saturation temperature, and phase diagrams.
- Components of steam distribution systems including piping, drainage, expansion, and insulation.
- Methods for sizing steam pipes to minimize pressure drop and optimize energy efficiency.
- The importance of proper steam trapping to remove condensate and maintain dry steam.
Combustion in an SI engine occurs in three stages:
1. The ignition lag stage is the delay between the spark and noticeable pressure rise from combustion. This allows the fuel-air mixture to heat up to its self-ignition temperature.
2. In the flame propagation stage, the flame front travels across the combustion chamber, releasing energy and increasing pressure.
3. The afterburning stage finishes combusting any remaining unburnt fuel-air mixture after the flame front passes.
Download Link (Copy URL):
https://sites.google.com/view/varunpratapsingh/teaching-engagements
This PPT contained slides for Steam distribution system, which is a third unit in Energy Conservation subject of final year in Mechanical Engineering Branch.
The content of PPT are mentioned below:
Steam Distribution System, Thermodynamics, Heat, Properties of steam, steam, steam system, PDRS, Steam pipe installation, Dryers, Operation and maintenance of steam traps, Condensate Recovery System, Flash Recovery System, Energy Conservation Opportunity in Steam Distribution System.
Steam distribution system, utilization and designAzmir Latif Beg
n any steam plant or any process plant effectiveness of steam distribution system is dependent upon the project specific conditions like location and layout of the process plant and its steam consuming equipment like heat exchangers, decorators etc. Steam distribution circuit is one of the major link between the steam production point and the point of end use i.e. process plant. Primary steam generating source are co-generation plant and Steam generators. However it not the source of steam generation but the effective and efficient steam distribution system that decides right quality (pressure and temperature) and quantity of steam to reach to the process through it. Thus designing of steam distribution is to be given due importance along with installation and subsequently maintenance during operation.
High pressure steam leakage from the high pressure to intermediate pressure turbine causes several issues:
- It increases calculated heat rate and intermediate pressure efficiency while decreasing low pressure efficiency.
- It decreases the mass flow rate through the downstream high pressure turbine.
- It can lead to load curtailment to avoid overheating reheat tubes or issues with thrust balance and control of reheat temperature.
Seal damage from misalignment, poor start-ups, or water induction incidents can cause the high pressure steam leakage. Replacements or repairs of damaged components like seals, snout rings, and shell joints may be needed to address the leakage.
Two methods to estimate the leakage are the temperature variance method and blow down method which uses
A boiler or steam generator is a device used to create steam by applying heat energy to water. Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure.
Steam flooding is a method used to improve heavy oil recovery after waterflooding. There are two main types: cyclic steam stimulation which uses a single well for injection and production over cycles, and steam flooding which continuously injects steam into multiple injection wells to drive mobilized oil towards producers. As steam is injected, it forms distinct zones - a condensing zone, saturated steam zone, transition zone, and displacement zone. Heat from steam reduces oil viscosity and interfacial tension, altering wettability and improving displacement of oil towards producers. Optimal recovery involves infill drilling, waterflooding after breakthrough, using low quality steam, and foaming additives to reduce gravity override.
Knocking occurs due to spontaneous combustion of the remaining fuel-air mixture after normal combustion. It results in an uncontrolled combustion process that generates shock waves and excessive pressure and temperature. Knocking happens when there are two flame fronts inside the engine cylinder rather than a uniform propagation of a single flame front from top to bottom. Factors that can cause knocking include poor fuel quality, improper engine cooling, and suboptimal engine design parameters such as valve size and position of fuel injectors.
1. A steam generator or boiler is a closed vessel made of steel that transfers heat from fuel combustion to water to generate steam.
2. Boilers should be safe, accessible for maintenance, efficient in absorbing heat, simple in construction, and have low initial and maintenance costs.
3. There are many types of boilers classified by factors like the contents in tubes (fire tube or water tube), furnace position, and circulation method. Proper consideration of factors like steam needs, area, and costs is important for boiler selection.
The document discusses different types of boilers, including fire tube and water tube boilers. It also describes the basic model of ignition and flame propagation in boilers. Key points covered include the conditions needed to form a stable flame during coal combustion, and the processes of nucleate/convective boiling and film boiling that occur as heat is transferred to water in boiler walls. Departure from nucleate boiling is explained, along with how it can be avoided by increasing pressure, fluid flow rate, or using a lower temperature bulk fluid.
The combustion process in a compression ignition (CI) engine occurs differently than in a spark ignition engine. In a CI engine, the air-fuel mixture is not homogeneous since the liquid fuel remains in particle form. Combustion takes place simultaneously at many points as the liquid fuel is evaporated, mixed with air, and raised to its ignition temperature. There are four stages of combustion in a CI engine: 1) an ignition delay period as the fuel is injected and begins to chemically react, 2) a premixed burning phase of maximum heat release, 3) a mixing-controlled combustion phase where fuel burns as it is injected, and 4) a tail/afterburning region where remaining unburned fuel continues burning into the
The document discusses abnormal combustion in spark ignition engines. Under normal combustion, the flame travels uniformly across the combustion chamber. Abnormal combustion occurs when combustion deviates from this normal behavior. Two types of abnormal combustion are pre-ignition and knocking. Pre-ignition occurs when the fuel-air mixture ignites before the spark, while knocking is the auto-ignition of unburned fuel late in the combustion cycle. Both pre-ignition and knocking can damage engine components and reduce performance. The causes of abnormal combustion include issues with fuel quality, engine parts, air quality, cooling, vibration, and operating environment.
This document provides an introduction to steam generators and boilers. It discusses the origin and impact of steam on science and technology. It describes the working principles of fire tube and water tube boilers. The key components and classifications of boilers are explained. The document also covers boiler efficiency, capacity, pressure, mountings, accessories and their functions. High pressure boilers and their types are discussed. The fuels used for steam generation and the analysis and grading of coal are summarized. Finally, the necessity and requirements of an effective coal handling system are outlined.
The document discusses combustion in compression ignition (CI) engines. It describes the four stages of combustion in CI engines: (1) ignition delay period, (2) uncontrolled combustion, (3) controlled combustion, and (4) after burning. It explains that the ignition delay period allows fuel to accumulate, causing uncontrolled combustion and a steep pressure rise when ignition occurs. Controlled combustion then follows, where combustion is matched to the fuel injection rate.
Interview Questions for Mechanical Engineering StudentsMoredhvaj giri
This document contains answers to various mechanical engineering interview questions. Some key points covered include:
1. Entropy decreases with increasing temperature due to entropy being inversely proportional to temperature.
2. Different engine specifications and exhaust passages produce different sounds in bikes despite using SI engines.
3. One horsepower equals 746.2 watts of power.
The document provides concise explanations and definitions for common mechanical engineering concepts and terms asked during job interviews.
ME6301 ENGINEERING THERMODYNAMICS SHORT QUESTIONS AND ANSWERS - UNIT IIIBIBIN CHIDAMBARANATHAN
This document provides an overview of thermodynamics concepts related to properties of pure substances and steam power cycles. It includes definitions of key terms like enthalpy of steam, latent heat of evaporation, superheated steam, dryness fraction, and critical point. The document also summarizes the assumptions and components of the Rankine cycle, methods to improve its efficiency including reheating, and comparisons to other cycles like Carnot. Overall, the document serves as a study guide for engineering thermodynamics topics focusing on steam as the working fluid.
1. The document discusses various air cycles used in internal combustion engines, including Otto, Diesel, and Brayton cycles. It compares features of spark ignition (SI) and compression ignition (CI) engines like efficiency, compression ratio, and applications.
2. Reciprocating engines are more efficient but heavier than gas turbines. Two-stroke engines are more compact but less efficient than four-stroke engines. SI engines use lower compression ratios and have smoother combustion, while CI engines are more efficient but heavier.
3. Knocking can occur in SI engines due to factors like fuel type, compression ratio, combustion chamber design, and engine speed. The octane rating indicates a fuel's resistance to knocking.
This document discusses vapor power cycles. It provides details on the classification and features of vapor power cycles. Specifically, it notes that vapor power cycles use a working substance that does not come into contact with fuel, allowing for easier achievement of isothermal processes. It then discusses the Rankine cycle in detail, outlining the key processes and assumptions made in analyzing vapor power cycles. The document also summarizes the effects of various parameters like condenser pressure and boiler pressure on cycle efficiency. Finally, it briefly introduces regenerative and reheat cycles which aim to improve upon the basic Rankine cycle.
All about Combined Cycle Power Plant, Combustion Chamber and Gas Turbine Blade Cooling. This presentation contains deep knowledge about related topic. I hope this will help you. Best of Luck.
This lecture discusses steam turbines and the Rankine cycle. It begins by outlining the learning objectives which are to understand the Rankine cycle, steam turbine configurations, and factors that affect turbine efficiency. It then provides details on the Rankine cycle processes and how modifications like high pressures and superheating can increase efficiency. The lecture describes impulse and reaction turbine designs as well as compounded turbine arrangements. It also discusses factors that cause erosion and corrosion in turbines and case studies of issues that have occurred. The lecture concludes with a student activity problem calculating shaft energy in an impulse turbine.
This document discusses vapor power cycles and combined power cycles. It provides information on sub-systems in a vapor power plant with a focus on sub-system A. The document then discusses the Rankine cycle as the ideal cycle for vapor power plants and compares it to the Carnot cycle. It also discusses the sequence of processes in the ideal Rankine cycle and performing energy analysis on the cycle. The document continues discussing actual vapor power cycles compared to the ideal cycle and ways to increase the efficiency of the Rankine cycle such as lowering condenser pressure, superheating steam, and increasing boiler pressure.
This document discusses vapor power cycles and combined power cycles. It covers the Carnot vapor cycle and how the Rankine cycle is better suited as a model for vapor power plants. Methods to increase the efficiency of the Rankine cycle are analyzed, including lowering the condenser pressure, superheating steam, increasing boiler pressure, using reheat cycles, and regenerative cycles. Combined cycles and cogeneration are also introduced.
This document summarizes heat transfer processes within internal combustion engines. It discusses how about one-third of the total chemical energy from fuel must be dissipated through heat transfer to keep engine materials from overheating. The hottest areas include around the spark plug, exhaust valve, and piston face. Engines use water jackets or fins to cool the engine block. During operation, heat is transferred through conduction, convection and radiation within the combustion chamber and throughout the engine. Maintaining proper heat transfer is critical for engine performance and durability.
This document discusses various thermodynamic power cycles used in internal combustion engines. It describes air standard cycles which approximate actual engine cycles using assumptions like ideal gas behavior and reversible processes. The key cycles covered are:
- Carnot cycle, the most efficient theoretical cycle but impractical to implement.
- Otto cycle for spark ignition engines, with efficiency increasing with compression ratio.
- Diesel cycle for compression ignition engines, allowing higher compression ratios and efficiencies than Otto cycle.
- Dual combustion cycle as a better approximation for modern diesel engines where combustion occurs in two stages.
The document analyzes each cycle thermodynamically and compares the efficiencies of Otto, Diesel and Dual cycles at
This document provides an overview of axial flow turbines and gas turbine combustors. It discusses how axial flow turbines work by compressing air, combusting fuel to increase temperature, and expanding the gas through the turbine to produce power. It notes advantages of axial turbines like their ability to handle high mass flows and ease of multi-staging. The document also summarizes key design considerations for gas turbine combustors like controlling outlet temperatures, stable combustion over a wide range of conditions, avoiding smoke and emissions, and meeting requirements for aircraft or industrial applications.
In any thermal power generation plant, heat energy converts into mechanical work. Then it is converted to electrical energy by rotating a generator which produces electrical energy.
INTRODUCTION
THERMODYNAMIC CYCLE OF STEAM FLOW
RANKINE CYCLE (IDEAL , ACTUAL ,REHEAT)
LAYOUT OF STEAM POWER PLANT
MAJOR COMPONENTS AND THEIR FUNCTIONS
ALTERNATOR
EXCITATION SYSTEM
GOVERNING SYSTEM
The document provides information on internal combustion engines, including:
- IC engines convert chemical energy from fuels like gasoline into mechanical work. They are used in vehicles, generators, and other machinery.
- The basic components of IC engines are cylinders, pistons, inlet/exhaust valves. Pistons move between top and bottom dead centers.
- IC engines are classified as either spark-ignition (gasoline) or compression-ignition (diesel) based on how combustion is initiated in the cylinder.
The document then discusses air standard cycles that model idealized versions of engine cycles, including the Otto cycle for gasoline engines and Diesel cycle for diesel engines. It provides analysis of the cycles
The document discusses diesel, gas turbine, and combined cycle power plants. It provides details on the layout and components of a diesel power plant, including the engine, air supply system, exhaust system, fuel system, cooling system, lubricating system, and starting system. It also discusses advantages like efficiency and disadvantages like noise pollution of diesel power plants. Open and closed cycle gas turbine power plants are compared, with open cycle plants having less weight but lower part-load efficiency. The ideal gas turbine cycle is the Brayton cycle of 4 processes - isentropic compression, constant pressure heat addition, isentropic expansion, and constant pressure heat rejection.
The Cyclone Engine is built of three major components, the Steam Generator, Piston Block, and Condenser. The working fluid, deionized water, travels continuously through these three components. Beginning in the steam generator, moving into the pistons, then to the condenser, and finally pumped back into the steam generator.
This document provides information about vacuum systems. It begins by defining vacuum and discussing the different levels or classifications of vacuum including rough, high, and ultra-high vacuum. It then explains various vacuum pump technologies used for different pressure ranges like rotary pumps, diffusion pumps, and cryopumps. It also covers vacuum measurement tools known as vacuum gauges and issues like leaks in vacuum systems. Overall, the document serves as an introduction to key concepts and components in vacuum technology.
This document provides information on entropy and thermodynamics concepts including:
1. Entropy is a measure of irreversibilities and increases for all actual processes, being conserved only for idealized reversible processes.
2. Processes can only occur in the direction that complies with the increase of entropy principle.
3. Gas turbine cycles including Brayton, jet propulsion, and modifications like regeneration, intercooling and reheating are discussed. The efficiency and performance of these cycles depends on parameters like pressure and temperature ratios.
The document contains multiple choice and short answer questions related to thermodynamics and heat engines. Some sample questions include identifying the process represented by lines on a T-s diagram, defining key thermodynamic cycles like Otto and Diesel, and calculating efficiency and heat supplied for ideal Brayton cycles. Short answer questions provide definitions for terms like refrigerating capacity and differentiate concepts such as normal and shear stress. Numerical problems involve truss analysis and calculating properties of gas turbine cycles.
This document discusses internal combustion engine combustion chambers. It describes the basic requirements of a good combustion chamber as providing high power output, high thermal efficiency, smooth engine operation, and reduced exhaust pollutants. It also discusses factors that influence combustion chamber design such as compression ratio, turbulence, heat loss, and scavenging. Different combustion chamber types are also enumerated such as T-head, L-head, I-head, and F-head chambers.
Project evaluation
This chapter sets out the principles and policies governing the evaluation of ILO-supported projects. It describes how the evaluation of project achievements improves decision-making, organizational learning, accountability and impact. The chapter clarifies roles and responsibilities and sets out the procedures for managing project evaluations.
Project evaluation is a systematic and objective assessment of an ongoing or completed project.1 The aim is to determine the relevance and level of achievement of project objectives, development effectiveness, efficiency, impact and sustainability. Evaluations also feed lessons learned into the decision-making process of the project stakeholders, including donors and national partners. Evaluation is also an important part of the ILO’s accountability to its donors and to the Governing Body.
This chapter provides information on:
♦♦♦♦♦
The concept and principles of project evaluation;
ILO policies for project evaluations and roles and responsibilities;
Preparing for an evaluation;
The implementation of project evaluation and evaluation report;
Follow-up, dissemination and knowledge sharing of evaluation outcomes.
Evaluating community projects
These guidelines were initially developed as part of the JRF Neighbourhood Programme. This programme is made up of 20 community or voluntary organisations all wanting to exercise a more strategic influence in their neighbourhood. The guidelines were originally written to help these organisations evaluate their work. They provide step-by-step advice on how to evaluate a community project which will be of interest to a wider audience.
What is evaluation?
Put simply, evaluation by members of a project or organisation will help people to learn from their day-to-day work. It can be used by a group of people, or by individuals working alone. It assesses the effectiveness of a piece of work, a project or a programme. It can also highlight whether your project is moving steadily and successfully towards achieving what it set out to do, or whether it is moving in a different direction. You can then celebrate and build on successes as well as learn from what has not worked so well.
Why evaluate?
Although evaluation may seem like an unnecessary additional task if you are already short of time and resources, it can save you both time and resources by keeping participants focused on, and working towards, the ultimate goal of the project. If necessary, it can refocus activity away from unproductive or unnecessary work.
Service parts management is the main component of a complete strategic service management process that
companies use to ensure that right spare part and resources are at the right place (where the broken part is) at
the right time.
Spare parts, are extra parts that are available and in proximity to a functional item, such as an automobile,
boat, engine, for which they might be used for repair.
Economic considerations
Spare parts are sometimes considered uneconomical since:
the parts might never be used
the parts might not be stored properly, leading to defects
maintaining inventory of spare parts has associated costs
parts may not be available when needed from a supplier
But without the spare part on hand, a company's customer satisfaction levels could drop if a customer has to
wait too long for their item to be fixed. Therefore, companies need to plan and align their service parts
inventory and workforce resources to achieve optimal customer satisfaction levels with minimal costs.
Measures of effectiveness
The effectiveness of spares inventory can be measured by metrics such as fill rate and availability of the end
item.
Routine maintenance is most often oil and filter changes, tire rotations, and various inspections. After the length of your warranty, routine maintenance often becomes more involved and more expensive. Car owners usually become aware of the need for routine maintenance at certain mileage intervals.
Fuel Economy: There are a number of ways that regular maintenance can help ensure you're getting the most out of your vehicle's fuel economy. For instance, making sure your tire pressure is set to the right levels can help prevent your car from expending unnecessary energy and fuel while moving.
Check your oil regularly and change it at the recommended intervals. This is perhaps the single most important thing you can do to keep your engine running well. Also make certain you change the filter as needed or recommended. Check your owner's manual for the correct oil weight to use.
50,000 miles: Replace worn parts such as brake pads; install a new fuel filter; drain and replace the automatic transmission fuel and filter. The exhaust system, muffler, catalytic converter, and suspension components should also be inspected and worn parts should be swapped out.
Which car brand has the highest maintenance cost?
Toyota
Toyota has emerged as the most economical brand when it comes to vehicle maintenance costs for a period of 10 years, while BMW and Mercedes-Benz hold their position of the highest maintenance cost vehicles.
Why is routine maintenance important?
Routine maintenance is considered one of the most important things you can do for your vehicle. A vehicle that receives regular service will contribute less to pollution, will use less fuel, will run more efficiently, and will last longer in contrast to a vehicle that does not receive routine maintenance.
Steel is graded as a way of classification and is often categorized into four groups—Carbon, Alloy, Stainless, and Tool. Carbon Steels only contain trace amounts of elements besides carbon and iron. This group is the most common, accounting for 90% of steel production.
What is the hardest steel grade?
Type 440—a higher grade of cutlery steel, with more carbon, allowing for much better edge retention when properly heat-treated. It can be hardened to approximately Rockwell 58 hardness, making it one of the hardest stainless steels.
Different Types of Steel
Carbon Steel. Carbon steel is dull and matte in appearance and is vulnerable to corrosion
Alloy Steel. Alloy steels are a mixture of several metals, including nickel, copper, and aluminum
Stainless Steel
1. MOTORISED OBJECT LIFTING JACK
2. KEY CONTROLLED- FORK LIFTER:
3. MATERIAL HANDLING (X, Y, Z MOTION CONTROL):
4. STEPPER MOTOR CONTROL WITH SELECTED STEPS FOR CONVEYOR BELT:
5. OBJECT REJECTION & COUNTING MACHINE:
6. ROBOTIC ARM WITH GRIPPER:
7. PNEUMATIC/HYDRAULIC ROBO ARM:
8. PNEUMATIC/HYDRAULIC CRANE:
9. PNEUMATIC/HYDRAULIC JACK:
10. ROBOTIC CRANE :
11. ROBOTIC TROLLEY FOR MATERIAL HANDLING:
12. AUTOMATIC STAMPING AND SORTING MACHINE FOR POSTCARD:
13. WINDMILL:
14. SOLAR SUN SEEKER:
15. THERMAL POWER PLANT USING STEAM:
16. HYDEL POWER DAM:
17. ELECTRICAL ENERGY FROM AMUSEMENT PARK RIDES (SEA-SAW, SWING, SLIDE, ROLLER ETC.)
18. ELECTRICAL ENERGY FROM SPEED BREAKER:
19. PADDLE CONTROLLED MOBILE CHARGER [censored] EMERGENCY LIGHT:
What is rack and pinion steering mechanismManish Nepal
What Is Rack And Pinion Steering Mechanism? | How Rack And Pinion Steering System Works?
STEERING SYSTEM | WORKING and COMPONENTS
Working of Four Wheel Steering System in Hindi | Advantages, and Disadvantages of 4-Wheel Steering
How Power Steering System Works?
Mechanical engineering important fluid mechanics mcq Manish Nepal
1) Shear stress in a turbulent flow is given by the formula
τ = η (du / dy)
Where η (eta) is,
a. eddy viscosity
b. apparent viscosity
c. virtual viscosity
d. all of the above
ANSWER: all of the above
2) Magnitude of eddy viscosity for laminar flow is
a. less than zero
b. zero
c. greater than zero
d. unpredictable
ANSWER: zero
3) Kinematic eddy viscosity (ε) is the ratio of
a. eddy viscosity (η) to dynamic viscosity (μ)
b. eddy viscosity (η) to kinematic viscosity (ν)
c. kinematic viscosity to eddy viscosity (η)
d. eddy viscosity (η) to mass density (ρ)
ANSWER: eddy viscosity (η) to mass density (ρ)
HANDLING
How well a vehicle moves on straightaways, around corners and over varying degrees of terrain.
HORSEPOWER
A unit of measurement equal to 550 foot pounds per second used to describe the power of a vehicle’s engine. Higher numbers mean more power and the ability to push a car to faster speeds.
IGNITION SYSTEM
The system that generates a spark and controls the timing of the spark that is necessary to ignite the fuel-air mixture and start fuel combustion inside the engine.
JUMP START
An emergency starting procedure used to get a car running when the battery is dead. Jumper cables are attached to the battery of a working vehicle and run to the failed battery to provide a jolt of power.
KEYLESS ENTRY
A modern entry system that unlocks doors via a battery-powered remote or key fob instead of requiring you to physically put the key into the lock.
OIL
Lubricant that reduces wear and tear on an engine’s moving parts, prevents overheating and delays the process of corrosion.
POWERTRAIN
This system consists of the combination of the engine and transmission and is often protected by a manufacturer warranty.
CHASSIS
A blanket description of the base frame of a vehicle and the mechanical parts that are attached to it, including the power train and suspension.
CLIMATE CONTROL
The term used to refer to the heater, air conditioner and defrosting mechanisms in a car. Some vehicles have advanced systems that detect outdoor temperatures and can be adjusted accordingly.
COOLANT
Also called antifreeze, this combination of ethylene glycol and water protects the climate control system by dispersing excess heat and preventing parts from freezing.
Automotive electrical circuits and wiring book Manish Nepal
Automotive electrical circuits and wiring
We will be identifying these items when we look at Automotive Circuits a little later in this book. There are three basic types of circuits: series, parallel, and series-parallel. The type of circuit is determined by how the power source, conductors, loads, and control or protective devices are connected.
Are cars wired in series or parallel?
A very simple car circuit diagram. ... The ignition circuit is an example of wiring in series. This means that all components receive the same amount of current. Car lights are always wired in parallel circuits.
In engineering, a mechanism is a device that transforms input forces and movement into a desired set of output forces and movement. Mechanisms generally consist of moving components that can include:
Gears and gear trains
Belt and chain drives
Cam and followers
Linkage
Friction devices, such as brakes and clutches
Structural components such as a frame, fasteners, bearings, springs, lubricants
Various machine elements, such as splines, pins, and keys.
The German scientist Reuleaux provides the definition "a machine is a combination of resistant bodies so arranged that by their means the mechanical forces of nature can be compelled to do work accompanied by certain determinate motion." In this context, his use of machine is generally interpreted to mean mechanism.
The combination of force and movement defines power, and a mechanism manages power to achieve a desired set of forces and movement.
A mechanism is usually a piece of a larger process or mechanical system. Sometimes an entire machine may be referred to as a mechanism. Examples are the steering mechanism in a car, or the winding mechanism of a wristwatch. Multiple mechanisms are machines.
What Are the Different Types of Steel?
Carbon Steels.
Alloy Steels.
Stainless Steels.
Tool Steels.
What is the most common type of steel?
The 3 Most Commonly used Types of Steel
Tool Steel. As the name suggests, tool steel is often used in the construction of tools. ...
Alloy Steel. Alloy steel is called such because it has small amounts of multiple alloying elements within it. ...
Carbon Steel.
How are the steel classified?
Steel is graded as a way of classification and is often categorized into four groups—Carbon, Alloy, Stainless, and Tool. Carbon Steels only contain trace amounts of elements besides carbon and iron. .Alloy steels contain alloying elements like nickel, copper, chromium, and/or aluminum
What is 350-grade steel?
Grade 350 Mild Steel is a medium strength structural steel plate product with a nominal yield strength of 350 MPa. Typical uses include General Fabrication.
What is the softest metal?
Cesium
Cesium is considered the softest metal, Lead is also considered among the softest metals. Answer 3: Mercury is liquid (molten) at room temperature. Gallium, while solid (if soft) at room temperature, is liquid at body temperature.
What are the examples of alloys?
Alloy. An alloy is a mixture of two or more metals. Some familiar examples of alloys include brass, bronze, pewter, cast and wrought iron, steel, coin metals, and solder (pronounced SOD-der; a substance used to join other metallic surfaces together).
What is the alloying of steel?
Alloy steels are made by combining carbon steel with one or several alloying elements, such as manganese, silicon, nickel, titanium, copper, chromium, and aluminum. These metals are added to produce specific properties that are not found in regular carbon steel.
What is the 500w TMT bar?
TMT 500W is a reinforcement bar that possesses yield strength of 500 Mega pascals. 'W' means this bar is weldable. TMT means Thermo Mechanically Treated. This is a new generation of high strength steel having superior properties.
Structures of Solids
The components can be arranged in a regular repeating three-dimensional array (a crystal lattice), which results in a crystalline solid, or more or less randomly to produce an amorphous solid. Crystalline solids have well-defined edges and faces, diffract x-rays, and tend to have sharp melting points
What are the different types of solids?
There are four different types of crystalline solids: molecular solids, network solids, ionic solids, and metallic solids. A solid's atomic-level structure and composition determine many of its macroscopic properties, including, for example, electrical and heat conductivity, density, and solubility.
What makes a solid a solid?
Solids can hold their shape because their molecules are tightly packed together. ... Atoms and molecules in liquids and gases are bouncing and floating around, free to move where they want. The molecules in a solid are stuck in a specific structure or arrangement of atoms.
What are the 2 types of solids?
Solids can be classified into two types: crystalline and amorphous. Crystalline solids are the most common type of solid. They are characterized by a regular crystalline organization of atoms that confer a long-range order.
What are the examples of solids?
Examples of Solids
Gold.
Wood.
Sand.
Steel.
Brick.
Rock.
Copper.
Brass.
What are the 3 characteristics of solids?
A solid has definite volume and shape, a liquid has a definite volume but no definite shape and gas has neither a definite volume nor shape.
...
Solids
Definite shape (rigid)
Definite volume.
Particles vibrate around fixed axes.
How do you describe solids?
A solid is a sample of matter that retains its shape and density when not confined. The adjective solid describes the state, or condition, of matter having this property. The atom s or molecule s of matter in the solid-state are generally compressed as tightly as the repulsive forces among them will allow.
What is the structure of a solid?
In a solid, molecules are packed together, and it keeps its shape. The matter is the "stuff" of the universe, the atoms, molecules, and ions that make up all physical substances. In a solid, these particles are packed closely together and are not free to move about within the substance
What are some properties of solids?
Explanation:
A solid has a definite shape and volume.
Solids, in general, have a higher density.
In solids, intermolecular forces are strong.
The diffusion of a solid into another solid is extremely slow.
Solids have high melting points.
What are the 4 types of structures?
There are four types of structures;
Frame: made of separate members (usually thin pieces) put together.
Shell: encloses or contains its contents.
Solid (mass): made almost entirely of matter.
liquid (fluid): braking fluid making the brakes.
Alloys are combinations or mixtures of elements.
Metals are alloyed to improve on properties of pure metals such as hardness, strength, corrosion resistance, etc.
Ex.:- Instead of pure aluminum an alloy of aluminum having a combination of Al –Zn –Mg – Cu – Mn(A five-element alloy ) is used to construct the aircraft body.
Alloys may behave differently when combined, some mix easily while others will only be soluble to a limited extent.
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
2. Mechanical Engineering Interview Questions and Answers
1. What is the difference between scavenging and supercharging?
Ans: Scavenging is process of flushing out burnt gases from engine cylinder by introducing fresh air in the
cylinder before exhaust stroke ends. Supercharging is the process of supplying higher mass of air by compressing
the atmospheric air.
2. What are the names given to constant temperature, constant pressure, constant volume, constant internal
energy, constant enthalpy, and constant entropy processes.
Ans: Isothermal, isochroic, isobaric, free expression, throttling and adiabatic processes respectively.
3. In a Rankine cycle if maximum steam pressure is increased keeping steam temperature and condenser pressure
same, what will happen to dryness fraction of steam after expansion ?Ans: It will decrease.
4. Why entropy change for a reversible adiabatic process is zero ?
Ans: Because there is no heat transfer in this process.
5. What are two essential conditions of perfect gas ?
Ans: It satisfies equation of state and its specific heats are constant.
6. Enthalpy and entropy are functions of one single parameter. Which is that ?
Ans: Temperature.
7. Why rate of condensation is higher on a polished surface compared to rusty surface ?
Ans: Polished surface promotes drop wise condensation and does not wet the surface.
8. How much resistance is offered to heat flow by drop wise condensation ?
Ans: Nil
How are these questions – please do add comments and if you like them please do share this post on facebook,
linkedin, twitter and google plus.
9. What is the relationship between COP of heating and cooling ?
Ans: COP of heating is one(unity) more than COP of cooling.
10. How much is the work done in isochoric process ?
Ans: Zero.
11. When maximum discharge is obtained in nozzle ?
Ans: At the critical pressure ratio.
12. Under what condition the work done in reciprocating compressor will be least ?
Ans: It is least when compression process approaches isothermal. For this purpose, attempts are made to cool the
air during compression.
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3. 13. What is the difference between stalling and surging in rotary compressions?
Ans: Stalling is a local phenomenon and it occurs when How breaks away from the blades. Surging causes
complete breakdown of flow and as such it affects the whole machine.
14. Why the electric motor of a fan with backward curved blades is never got overloaded under any condition?
Ans: The maximum power is consumed at about 70% of maximum flow in case’of fan with backward blades.
For higher flow, power consumption gets lower.
15. Why the work per kg of air flow in axial flow compressor is less compared to centrifugal compressor for
same pressure ratio ?
Ans: Isentropic efficiency of axial flow compressor is higher.
16. Whatisthe namegiventoportionof thermalenergytobe necessarilyrejectedtoenvironment?
Ans: Anergy.
17. What is pitting ? How it is caused ?
Ans: Non uniform corrosion over the entire metal surface, but occuring only in small pits is called pitting. It is
caused by lack of uniformity in metal.
18. What is caustic embrittlement ?
Ans: It is the actual physical change in metal that makes it extremely brittle and filled with minute cracks. It
occurs particularly in the seams of rivetted joints and around the rivet holes.
19. Which impurities form hard scale and which impurities soft scale ?
Ans: Sulphates and chlorides of lime and magnesium form hard scale, and carbonates of lime and magnesium
form soft scale.
20. What is the difference between hard water and soft water?
Ans: Hard water contains excess of scale forming impurities and soft water contains very little or no scale
forming substances.
21. Which two elements in feed water can cause corrosion of tubes and plates in boiler ? ‘
Ans: Acid and oxygen in feed water lead to corrosion.
22. What should be done to prevent a safety valve to stick to its seat ?
Ans: Safety valve should be blown off periodically so that no corrosion can take place on valve and valve seat.
23. Why large boilers are water tube type ?
Ans: Water tube boilers raise steam fast because of large heat transfer area and positive water circulation.
Thus they respond faster to fluctuations in demand. Further single tube failure does not lead to catastrophy.
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4. 24. What type of boiler does not need a steam drum ?
Ans: Super-critical pressure boiler.
25. Why manholes in vessels are usually elliptical in shape ?
Ans: Elliptical shape has minimum area of opening and thus plate is weakened the least. Further it is very
convenient to insert and take out the cover plate from elliptical opening.
26. Low water in boiler drum is unsafe because it may result in overheating of water tubes in furnace. Why it is
unsafe to have high water condition in boiler drum ?
Ans: High drum level does not allow steam separation to be effective and some water can be carried over with
steam which is not desirable for steam turbine.
27. Why boiler is purged everytime before starting firing of fuel ?
Ans: Purging ensures that any unburnt fuel in furnace is removed, otherwise it may lead to explosion.
28. What is the principle of mechanical refrigeration ?
Axis. A volatile liquid will boil under the proper conditions and in so doing will absorb heat from surrounding
objects.
29. Why high latent heat of vaporisation is desirable in a refrigerant?
Ans: A high latent heat of vaporisation of refrigerant results in small amount of refrigerant and thus lesser
circulation system of refrigerant for same tonnage.
30. What is the critical temperature of a refrigerant ?
Ans: Critical temperature is the maximum temperature of a refrigerantrat which it can be condensed into
liquid and beyond this it remains gas irrespective of pressure applied.
31. Maximum combustion temperature in gas turbines is of the order of 1100 to 10°C whereas same is around
00°C in I.C. engine ? Why ?
Ans: High temperature in I.C. engine can be tolerated because it lasts for a fraction of second but gas turbines
have to face it continuously which metals can’t withstand.
32. Why efficiency of gas turbines is lower compared to I.C. engines ?
Ans: In gas turbines, 70% of the output of gas turbine is consumed by compressor. I.C. engines have much
lower auxiliary consumption. Further combustion temperature of I.C. engines is much higher compared to gas
turbine.
33. What do you understand by timed cylinder lubrication ?
Ans: For effective lubrication, lub oil needs to be injected between two piston rings when piston is at bottom of
stroke so that piston rides in oi during upward movement. This way lot of lub oil can be saved and used
properly.
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5. 34. What is IIUCR in relation to petrol engine ?
Ans: HUCR is highest useful compression ratio at which the fuel can be used in a specific test engine, under
specified operating conditions, without knocking.
35. In some engines glycerine is used in place of water for cooling of engine. Why ?
Ans: Glycerine has boiling point of 90°C which increases its heat carrying capacity. Thus weight of coolant gets
reduced and smaller riadiator can be used.
36. Whyconsumptionoflubricatingoilismoreintwo-strokecyclepetrolenginethanfour-strokecyclepetrol
engine ?
Ans: In two-stroke engine lub oil is mixed with petrol and thus some lub oil is blown out through the exhaust
valves by scavenging and charging air. There is no such wastage in four stroke petrol engine.
37. As compression ratio increases, thermal n increases. How is thermal n affected by weak and richmixture
strength ?
Ans: Thermal n is high for weak mixture and it decreases as mixture strength becomes rich.
38. How engine design needs to be changed to burn lean mixture ?
Ans: Engine to burn lean mixture uses high compression ratio and the highly turbulent move¬ment of the
charge is produced by the geometry of the combustion chamber.
39. Horse power of I.C. engines can be expressed as RAC rating, SAE rating, or DIN rating. To which countries
these standards belong ?
Ans: U.K., USA and Germany respectively.
40. What is the use of flash chamber in a vapour compression refrigeration cycle to improve the COPof
refrigeration cycle?
Ans: When liquid refrigerant as obtained from condenser is throttled, there are some vapours. These vapours if
carried through the evaporator will not contribute to refrigerating effect. Using a flash chamber at some
intermediate pressure, the flash vapour at this pressure can be bled off and fed back to the compression process.
The throttling process is then carried out in stages. Similarly compression process is also done in two separate
compressor stages.
41. Why pistons are usually dished at top?
Ans: Pistons are usually hollowed at top to (i) provide greater spa’e for combustion, (ii) increase surface for flue
gases to act upon, and (iii) better distribution of stresses.
42. Whatisthe functionof thermostatincooling system of anengine ?
Ans: Thermostat ensures optimum cooling because excessive cooling decreases the overall efficiency. It allows
cooling water to go to radiator beyond a predetermined temperature.
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7. 48. How the thickness of thermal boundary layer and thickness of hydrodynamic boundary layer related ?
Ans: Ratio of their thickness = (Prandtl number)-1/3.
49. What is the effect of friction on flow of steam through a nozzle ?
Ans: To decrease both mass flow rate and wetness of steam.
50. Why gas turbine power plant needs efficient compressor ?
Ans: Because a large portion of turbine work is eaten away by compressor and its inefficiency will affect net
power output and cost of generation.
51. Why rockets using liquid hydrogen have higher specific impulse compared to liquid hydrocarbon ?
Ans: Liquid hydrogen has higher burning velocity.
52. Why axial flow compressor is preferred for gas turbines for aeroplanes ?
Ans: Because it has low frontal area.
53. What is the effect of inter cooling in gas turbines ?
Ans: It decreases thermal efficiency but increases net output.
54. Why iso-octane is chosen as reference fuel for S.I. engines and allotted 100 value for its octane number ?
Ans: Iso-octane permits highest compression without causing knocking.
55. Why thermal efficiency of I.C. engines is more than that of gas turbine plant ?
Ans: In I.C. engine maximum temperature attained is higher than in gas turbine.
56. Which are the reference fuels for knock rating of S.I. engines ?
Ans: n-heptane and ISO-octane.
57. When effect of variations in specific heats is considered then how do maximum temperature and pressure
vary compared to air standard cycle?
Ans: Temperature increases and pressure decreases.
58. Quantities like pressure, temperature, density, viscosity, etc. are independent of mass. What are these
called?
Ans: Intensive properties.
59. The amount of radiation emitted per scm per sec is called ….?
Ans: Emissive power.
60. In convection heat transfer, if heat flux intensity is doubled then temperature
difference between solid surface and fluid will ?
Ans: Get doubled.
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8. 61. How you can define coal ?
Ans: Coal is a naturally occurring hydrocarbon that consists of the fossilised remains of buried plant debris that
have undergone progressive physical and chemical alteration, called coalification, in the course of geologic time.
62. Which pollutant is major greenhouse gas and what is its effect ?
Ans: CO is major greenhouse gas and it traps the radiation of heat from the sun within earth’s atmosphere.
63. In order to increase efficiency and reduce CO emissions and other emissions, clear coal technologies are
receiving major attention. What are these ?
Ans: (i) Advanced pulverised and pressurised pulverised fuel combustion.
(ii) Atmospheric fluidised bed combustion and pressurised fluidised bed combustion.
(iii) Supercriticalboilers.
(iv) Integrated gasification combined cycle systems.
(v) Advanced integrated gasification, including fuel cell systems.
(vi) Magneto hydrodynamic electricity generation.
64. What are the important operational performance parameters in design of fuel firing equipment ?
Ans: Fuel flexibility, electrical load following capability, reliability, availability, and maintenance ease.
65. What is the differenc between total moisture and inherent moisture in coal ?
Ans: The moisture content of the bulk as sampled is referred to as total moisture, and that of the air dried
sample is called inherent moisture.
66. Proximity analysis of coal provides data for a first, general assessment of a coal’s quality and type. What
elements it reports ?
Ans: Moisture, volatile matter, ash and fixed carbon.
67. Ultimate analysis of coal is elementary analysis. What it is concerned with ?
Ans: Carbon, hydrogen, nitrogen, and sulphur in coal on a weight percentage basis.
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9. 68. Explain the difference between AFBC, BFBC, PFBC and PCFB in regard to fluidised bed technologies.
Ans: AFBC (Atmospheric fluidised bed combustion) process consists of forming a bed of inert materials like
finely sized ash or ash mixed with sand, limestone (for sulphur removal), and solid fuel particles in a combustor
and fluidising it by forcing combustion air up through the bed mixture. The gas flows thorugh bed without
disturbing particles significantly but gas velocity is high enough to support the total weight of bed (fluidisation).
At slightly higher velocity excess gas passes through the bed as bubbles (fluidised bed) and gives the bed the
appearance of a boiling liquid.
Bubbling fluidised bed combustion (BFBC) has a defined height of bed material and operates at or near
atmospheric pressure in the furnace.
Pressurised fluidised bed combustion (PFBC) system operates the bed at elevated pressure. Exhaust gases have
sufficient energy to power a gas turbine, of course, gases need to be cleaned.
In fluidised combustion, as ash is removed some unburned carbon is also removed resulting in lower efficiency.
In circulating fluidised bed combustion (CFBC) system, bed is operated at higher pressure leading to high heat
transfer, higher combustion efficiency, and better fuel feed. Circulating fluidised beds operate with relatively
high gas velocities and fine particle sizes. The maintenance of steady state conditions in a fast fluidised bed
requires the continuous recycle of particles removed by the gas stream (circulating bed). The term circulating
bed is often used to include fluidised bed sys¬tems containing multiple conventional bubbling beds between
which bed material is exchanged.
69. What for Schmidt plot for is used in heat transfer problems ?
Ans: Schmidt plot is a graphical method for determining the temperature at any point in a body at a specified
time during the transient heating or cooling period.
70. In which reactor the coolant and moderator are the same ?
Ans: Pressurised water reactor.
71. Which reactor has nomoderator ?
Ans: Fast breeder reactor.
72. What are thermal neutrons ?
Ans: Thermal neutrons are slow neutrons (having energy below 1 eV) which are in thermal equilibrium with
their surroundings.
73. What is big advantage of fast breeder reactor ?
Ans:Ithasrapidselfbreedingoffissile fuelduringtheoperationofthereactor,andthus,itoffersaboutsixty
timesthe output withsame natural uranium resourcesthrough ordinary non-breeder nuclear reactor.
74. What is the purpose of biological shield in nuclear plants?
Ans: Biological shield of heavy concrete prevents exposure to neutrons, beta rays and gamma rays which kill
living things.
75. Which two elements have same percentage in proximate and ultimate analysis of coal?
Ans: Moisture and ash.
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12. 91. Which reactor produces more fissionable material than it consumes ?
Ans: Breeder reactor.
92. Which reactor uses natural uranium as fuel ?
Ans: Gas cooled reacator.
93. Which reactor uses heavy water as moderator ?
Ans: CANDU.
94. Which reactor requires no moderator ?
Ans: Breeder reactor.
95. Which reactor uses primary coolant as fluoride salts of lithium, beryllium, thorium and uranium ?
Ans: Molten salt breeder reactor.
96. Why an increase in area is required to produce an increase of velocity in case of supersonic flow ?
Ans: Increase in area for increase in velocity for supersonic flow is required because the density decreases faster
than velocity increases at supersonic speeds and to maintain continuity of mass, area must increase.
97. Under what circumstances would there be an increase in pressure in a diver¬gent nozzle ?
Ans: For subsonic flow at inlet section of a diffuser a lower velocity and higher pressure will exist at the exit
section. For supersonic isentropic flow at the inlet section a higher velocity and lower pressure will exist at the
exit but if a shock wave occurs in the diffuser then a higher pressure will exist at the exit.
98. Why water can’t be used as refrigerant for small refrigerating equipment ?
Ans: The refrigerant should be such that vapour volume is low so that pumping work will be low. Water
vapour volume is around 4000 times compared to R- for a given mass.
99. Whichparameter remainsconstantina throttling process?
Ans: Enthalpy.
100. What is the difference between isentropic process and throttlinglprocess ?
Ans: In isentropic process, heat transfer takes place and in throttling process, enthalpy before and after the
process is same.
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13. MECHANICAL Interview Questions with Answers Part Two
1. What is the difference between isotropic and anisotropic materials ?
Ans: If a material exhibits same mechanical properties regardless of loading direction, it is isotropic, e.g.,
homogeneous cast materials. Materials lacking this property are anisotropic.
2. What are orthotropic materials ?
Ans: It is a special class of anisotropic materials which can be described by giving their prop¬erties in three
perpendicular directions e.g. wood; composites.
3. What is view factor ?
Ans: View factor is dependent upon geometry of the two surfaces exchanging radiation.
4. What properties need to be considered for applications calling for following re¬quirements :
(i) rigidity
(ii) strength for no plastic deformation under static load
(iii) strength to withstand overload without fracture.
(iv) wear resistance
(v) reliability andsafety.
Ans: (i) Rigidity—Elastic modulus and yield strength
(ii) Strength (for no plastic deformation under static loading)—yield point
(iii) Strength (overload)—Toughness and impact resistance
(iv) Wear resistance—Hardness
(v) Reliability and safety—Endurance limit and yield point.
5. Explain the effects of alloying chromium and nickel in stainless steel.
Ans: Addition of nickel and chromium increases the tensile strength and increase in resistance to corrosion
takes place.
6. Mention two types of dislocations.
Ans: Dislocation refers to a break in the continuity of the lattice. In edge dislocation, one plane of atoms gets
squeezed out. In screw dislocation the lattice atoms move fom their regular ideal positions.
7. What are the principal constituents of brass?
Ans: Principal constituents of brass are copper and zinc.
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14. 8. What is Curie point ?
Ans: Curie point is the temperature at which ferromagnetic materials can no longer be magnetised by outside
forces.
9. Specific strength of materials is very high when they are in fibre size but lower when they are in bar form
Why ?
Ans: Crystal structure has ordered, repeating arrangement of atoms. Fibres are liable to maintain this and
thus have high specific strength. As size increases, the condition of ordered and repeating arrangements can’t
be guaranteed because of several types of defects and dislocations and thus the specific strength gets lower.
10. What is the percentage of carbon in cast iron ?
Ans: 2.5%.
11. Which element is added in steel to increase resistance to corrosion ?
Ans: Chromium.
12. Whetherindividualcomponentsincompositematerialsretaintheircharacteristicsornot?
Ans: yes.
13. An elastomer is a polymer when its percentage elongation rate is ?
Ans: Greater than 100%.
14. If percentage elongation of a material is more than 200%, it is classed as ?
Ans: Rubber.
15. Why is it that the maximum value which the residual stress can reach is the elastic limit of the material ?
Ans: A stress in excess of elastic limit, with no external force to oppose it, will relieve itself by plastic
deformation until it reaches the value of the yieldstress.
16. Why fatigue strength decreases as size of a part increases beyond around 10 mm?
Ans: Perfection of material conditions is possible at lower sizes and as size increases, it is not possible to attain
uniform structure of the material.
17. Distinguish between creep and fatigue.
Ans: Creep is low and progressive deformation of a material with time under a constant stress at high
temperature applications. Fatigue is the reduced tendency of material to offer resistance to applied stress
under repeated or fluctuating loading condition.
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15. 18. While normal carburising and nitriding surface treatments increase fatigue strength, excessive treatment
may decrease the fatigue strength. Why?
.Ans: Normal carburising/nitriding treatments increase volume due to phase transformation at Surface and
introduce residual compressive surface stress and thus increase the fatigue strength. By excessive treatment the
high compressive stresses are introduced but these are balanced by high in¬ternal tensile stresses of equal value
and the subsurface fatigue cracks may develop in the regions of high tensile stress and lead to early fatigue
failure.
19. List at least two factors that promote transition from ductile to brittle fracture.
Ans: Manner of loading, and the rate of loading promote transition from ductile to brittle frac¬ture. A machine
member may have ductile failure under static loading but may fail in brittle fashion when the load is fluctuating.
Similarly a material may evidence ductile failure under tensile loading at ordinary testing speed but if load is
applied at a high velocity then failure may be brittle.
20. Which theories of failure are used for (a) ductile materials, and (B) brittle materials ?
Ans: For ductile materials, theories of failure used are maximum shear stress theory, and maximum energy of
distortion theory; while for brittle materials, theory of maximum principal stress, and maximum strain are used.
21. What does thermal diffusivity of metals signify.
Ans: Thermal diffusivity is associated with the speed of propagation of heat into solids during changes in
temperature with time.
22. For conduction of heat, the instantaneous rate of heat flow is product of three factors. What are these ?
Ans: (i) Area of the section of the heat flow path, perpendicular to the direction of heat flow.
(ii) temperature gradient, i.e. change of temperature w.r.t. length of path.
(ii) Thermal conductivity of material.
23. How convective heat transfer is effected and on what factors it depends ?
Ans: Convective heat transfer is effected between a solid and fluid by a combination of molecular conduction
within the fluid in combination with energy transport resulting from the motion of fluid particles. It depends on
boundary layer configuration, fluid properties and temperature difference.
24. Which is the common element between brass and bronze ?
Ans: Copper.
25. What does following alloy designation indicate FG 250 ?
Ans: Grey cast iron with tensile strength of 250 MPa.
26. How is ceramic defined?
Ans: It is a solid formed by combination of metallic and non-metallic elements.
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16. 27. Give one example of metal classified as per structure as BCC, FCC, HCP and CCP.
Ans: BCC (body centred cubic) structure—Molybdenum
FCC (face centred cubic) structure—Aluminium
HCP (hexagonal closed packed) structure—Zinc
CCP (cubic dosed packed) structure-Copper.
28. What is the name of solid solution of carbon in alpha iron and delta iron ?
Ans: Ferrite and austenite respectively.
29. Explain the difference between pearlite and cementile ?
Ans: Pearlite is eutectoid mixture of ferrite and cementile. Cementite is chemical compound of iron and
carbon.
30. Give one example each of the following proportion of materials dimensional, physical, technological and
mechanical.
Ans: Roughness, enthalpy, toughness, and hardness respectively.
31. For which parts the Wahl factor and Lewis form factor used ?
Ans: For springs and gears respectively.
32. How oxygen can be removed from steel during melting? What are fully killed steels ?
Ans: Oxygen can be removed by adding elements such as manganese, silicon or aluminium which, because of
their high affinity for oxygen, react with it to form non-metallic oxides which rise into the slag. Steels which
have had most of their dissolved oxygen removed are called “fully killed steels”.
33. Hydrogen cannot be removed easily from molten steel. What harm hydrogen has on property of steel ?
Ans: Execessive hydrogen results in the formation of small fissures often described as hairline cracks or flakes
in the steel. Large forgings in alloy steel are particularly sensitive to this phenom¬enon.
34. What is allotrope ? In what forms of cubic pattern, iron exists?
Ans: Some elements exist in more than one crystalline form. Each form is known as “allotrope”. Iron exists in
two forms of cubic pattern, namely body centered cubic (bcc) and face-centered cubic (fee).
35. What is the difference between alpha iron, delta iron and gamma iron ?
Ans: The bcc form of iron exists between room temperature and 910°C, and between 1400°C and the melting
point at 1539°C. The lower temperature form is known as “alpha”-iron and the higher temperature form as
“delta”-iron. The face-centered cubic form existing between 910°C and 1400°C is referred to as “gamma-iron”.
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17. 36. Metals, in general are of low strength and do not possess required physio-chemical and technological
properties for a definite purpose. Alloys are therefore more than metals alone. Discuss the arrangement of
atoms and structures of alloys.
Ans: Alloys are produced by melting or sintering two ore more metals, or metals and a non-metal, together.
Alloys possess typical properties inherent in the metallic state. The chemical elements that make up an alloy
are called its components. An alloy can consist of two or more components. The phase and structures ofalloys
describe the constitution, transformations and properties of metals and alloys. A combination of phases in a
state of equilibrium is called a system. A phase is a homogeneous portion of a system having the same
composition and the same state of aggregation throughout its volume, and separated from the other portions
of the system by interfaces. For instance, a homogeneous pure metal or alloy is a single-phase system. A state
in which a liquid alloy (or metal) coexists with its crystals is a two-phase system. Structure refers to the shape,
size or the mutual arrangement of the corresponding phases in metals or alloys. The structural components of
an alloy are its individual portions, each having a single structure with its characteristic features.
37. What is the difference between isotropic material and homogeneous material ?
Ans: In homogeneous material the composition is same throughout and in isotropic material the elastic
constants are same in all directions.
38. Explain the difference between the points of inflexion andcontraflexure.
Ans: At points of inflexion in a loaded beam the bending moment is zero and at points of contraflexure in
loaded beam the bending moment changes sign from increasing to decreasing.
39. What is the difference between proof resilience and modulus of resilience ?
Ans: Proof resilience is the maximum strain energy that can be stored in a material without permanent
deformation. Modulus of resilience is the maximum strain energy stored in a material per unit volume.
40. What is the difference between column and strut ?
Ans: Both column and strut carry compressive load. Column is always vertical but strut as member of
structure could carry axial compressive load in any direction.
41. Explain the difference between ferrite, austenite and graphite?
Ans: Ferrite is the solid solution of carbon and other constituents in alpha-iron. It is soft, ductile and relatively
weak.
Austenite is the solid solution of carbon and other constituents in gamma-iron. It exists in ordinary steels at
elevated temperatures, but it is also found at ordinary temperatures in some stainless steels.
Graphite has a hexagonal layer lattice. ‘
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18. 42. Explain the terms solid solution, eutectic, eutectoid and peritectic.
Ans: Solid Solution. When a homogeneous mixture of two (or more) atomic forms exists in solid state, it is
known as solid solution.
Eutectic. A mixture of two (or more) phases which solidify simultaneously from the liquid al¬loy is called an
eutectic. Alloys in which the components solidify simultaneously at a constant tem¬perature the lowest for
the given system, are called eutectic alloys.
Eutectoid. Eutectoid alloys are the alloys for which two solid phases which are completely soluble become
completely insoluble on cooling before a certain temperature called eutectoid tem¬perature.
Peritectic. A peritectic transformation involves a reaction between a solid and liquid that form a different and
new solid phase. This three phase transformation occurs at a point called peritectic point.
43. What do you understand by critical points in iron, iron-carbide diagram ?
Ans: The temperatures at which the phase changes occur are called critical points (or tem¬peratures).
45. Why PERT is preferred over CPM for evaluation of project ?
Ans: PERT is based on the approach of multiple time estimates for each activity.
46. What is the percentage of chromium in 18 : 4 : 1 IISS ?
Ans: 4%.
47. What is stellite?
Ans: It is a non-ferrous cast alloy containing cobalt, chromium and tungsten.
48. Which rays are produced by cobalt-60 in industrial radiography ?
Ans: Gamma rays.
49. What are killed steels and what for these are used ?
Ans: Killed steels are deoxidised in the ladle with silicon and aluminium. On solidification no gas evolution
occurs in these steels because they are free from oxygen.
50. What is critical temperature in metals ?
Ans: It is the temperature at which the phase change occurs in metals.
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19. 51. Car tyres are usually made of ?
Ans: Styrene-butadine rubber.
52. What is the structure of pure iron and whether it is soft or hard ?
Ans: Ferrite and it is soft.
53. Which elements increase the corrosion resistance of steel?
Ans: Chromium and nickel.
54. What causes hardness in steel ? How heat treatment alters properties of steel?
Ans: The shape and distribution of the carbides in the iron determines the hardness of the steel. Carbides can
be dissolved in austenite is the basis of the heat treatment of steel. If steel is heated above the A critical
temperature to dissolve all the carbides, and then cooled, suitable cooling through the cooling range will
produce the desired size and distribution of carbides in the ferrite, imparting different properties.
55. Explain the formation of microstructures of pearlite, bainite and martensite in steel.
Ans: If austenite containing about 0.80 percent carbon is slowly cooled through the critical temperature,
ferrite and cementite are rejected simultaneously, forming alternate plates or lamellae. This microstructure is
called pearlite. At temperatures just belot the A1, the transformation from austenite.to pearlite may take an
appreciable time to initiate and complete, but the product will be lameller pearlite. As the transformation
temperature is lowered, the time to initiate transformation shortens but the product is pearlite of increasing
fineness, and at temperatures approaching 550°C it cannot be resolved into its lamellar constituents. Further
deerease in transformation temperature causes a lengthening of the ncubation period and a change in
structure of the product to a form known as “bainite”.
If the temperature is lowered sufficiently, the diffusion controlled nucleation and growth modes of
transformation are suppressed completely and the austenite transforms by a diffusionless process in which the
crystal lattice effectively shears to a new crystallographic configuration known as “martensite”. This phase has
a tetragonal crystal structure and contains carbon in supersaturated solid solution.
56. Howwithalloyingofsteelitispossibletoaachievepropertieswhichcannotbeachievedwithheat
treatment?
Ans: A prerequisite to the hardening of steels is that martensite should be formed on cooling, but this can only
be achieved if the rate of cooling is great enough to suppress the formation of pearlite or bainite and in plain
carbon steels this can be achieved by quenching relatively small specimens
57. What are the major effects of alloying elements?
Ans: (1) To alter the transformation temperatures and times
(2) To modify the room temperature and elevated temperature strengths of given structures by (a) stiffening
the crystals and (B) introducing complex precipitates which tend to harden the steel.
(3) To modify the type of oxide film formed on the surface of the steel and thereby affect its corrosion
resistance.
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20. 58. What is the difference between austenite stabilisers and ferrite stabilisers ?
Ans: Austenite stabilisers have the effect of extending the temperature range overwhich austenite is formed.
Such elements are carbon, manganese, nickel, copper and cobalt.
Ferrite stabilisers have the effect of extending the temperature range over which alpha and delta ferrite are
formed, which consequently reduces temperature range over which austenite is formed. Such elements are
silicon, chromium, molybdenum, tungsten, titanium and niobium.
59. What are the effects of carbon on the properties of steel.
Ans: In general, an increase in carbon content produces higher ultimate strength and hardness but lowers
ductility and toughness of steel alloys. Carbon also increases air-hardening tendencies and weld hardness,
especially in the presence of chromium. In low-alloy steel for high-temperature applications, the carbon
content is usually restricted to a maximum of about 0.15% in order to assure optimum ductility for welding,
expanding, and bending operations. To minimize intergranular corro¬sion caused by carbide precipitation,
the carbon content of austenitic (18-8 type) alloys is limited in commercial specifications to a maximum of
0.08%, or even less, i.e. 0.03% in the extremely low-carbon grades used in certain corrosion-resistant
applications.
In plain carbon steels in the normalised condition, the resistance to creep at temperatures below 440°C
appears to increase with carbon content up to 0.4% carbon, at higher temperatures there is
but little variation of creep properties with carbon content.
An increase in carbon content lessens the thermal and electrical conductivities of steel and increases its
hardness on quenching.
60. What is the role of silicon as alloying element in steels ?
Ans: Silicon contributes greatly to the production of sound steel because of its deoxidizing and degasifying
properties. When added in amounts up to 2.5%, the ultimate strength of the steel is increased without loss in
ductility. Silicon in excess of 2.5% causes brittleness, and amounts higher than 5% make the steel non-
malleable.
Resistance to oxidation and surface stability of steel are increased by the addition of silicon. These desirable
effects partially compensate for the tendency of silicon to lower the creep properties of steel. Silicon increases
the electrical resistivity of steel and decreases hysteresis losses.
61. Discuss the role of manganese in alloying steels.
Ans: Manganese is an excellent deoxidizer and sulfur neutralizer, and improves the mechanical properties of
steel, notably the ratio of yield strength to tensile strength at normal temperatures. As an alloying element,
manganese serves as an inexpensive means of preventing “hot shortness”. It improves rolling properties,
hardenability, and resistance to wear. However manganese increases the crack sensitivity of weldments,
particularly with steels of higher carbon content.
62. Define buckling factor.
Ans: It is the ratio of the equivalent length of column to the minimum radius of gyration.
63. What do you understand by catenary cable ?
Ans: A cable attached to the supports and carrying its own weight.
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21. 64. What is coaxing?
Ans: It is the process of improving fatigue properties by first under-stressing and then increasing the stress in
small increments.
65. What is difference between conjugate beam and continuous beam ?
Ans: A conjugate beam is an imaginary beam of same size as original beam and carrying a distributed load in
accordance with the bending moment diagram.
A continuous beam is one which is resting on more than two supports.
66. What is isotropic material ?
Ans: It is a material having same elastic constants in all directions.
67. Explain difference between modulus of resilience and modulus of rigidity ?
Ans: Modulus of resilience is the maximum strain energy stored in a material per unit volume and modulus
of rigidity is the ratio of shearing stress to the shearing strain within the elastic limit.
68. What is the difference between basic hole and basic shaft ?
Ans: A basic hole is one whose lower deviation is zero and in case of basic shaft the upper deviation is zero.
69. What for pyranometer is used ?
Ans: It is used to measure the total hemispherical solar radiation.
70. Describe transfer machines in brief.
Ans: It is an automatic machine in which workpiece alongwith fixture is transferred from one station to other
automatically and several operation on workpiece are performed at each station.
71. What is burnt-out point ?
Ans: It corresponds to maximum heat flux at which transition occurs from nucleate boiling to film boiling.
72. What do you understand by eutectic ?
Ans: It is mechanical mixture of two or more phases which solidify simultaneously from the liquid alloy.
72. Explain the difference between grey iron and white iron. What is mottled iron ?
Ans: The carbon in cast iron could exist at room temperature as either iron carbide, or as graphite which is
the more stable form. Irons containing carbon as graphite are soft, easily machinable and are called “grey
irons”. Irons with carbon present as iron carbide are extremely hard, difficult to machine and are called
“white” irons. Irons with fairly equal proportions of graphite and iron carbide have intermediate hardness
and are called “mottled” irons.
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23. 81. What is the maximum use of magnesium ?
Ans: Magnesium is used to alloy with aluminium and as an additive for making SG (Spheroidal Graphite) iron.
82. What for zinc finds applications ?
Ans: Galvanizing consumes the largest proportion of zinc. Zinc is resistant to corrosion but is attacked by acids
and alkalies. Zinc alloy.s are suited for making die casting since the melting point is reasonably low.
83. Which factors influence the type of fracture in failure of a material ?
Ans: Seven factors influencing type of failure are :
(i) Type of material (inherent structure properties),
(ii) Manner of loading (Static versus dynamic),
(iii) Range of imposedstress,
(iv) Strain rate (static, dynamic, impact),
(v) Stress distribution (discontinuity in material/shape),
(vi) temperature,and
(vii) surface treatment.
84. What is the name given to ratio of actual cycle efficiency and ideal cycle efficiency.
Ans: Efficiency ratio.
85. List two effects of manganese in plain carbon steels. ,
Ans: Manganese increases tensile strength and hardness. It decreases weldability.
86. Name the strongest and weakest type of atomic bonds.
Ans: Metallic bond is strongest and molecular bond also known as Vander Waals bond is weakest.
87. In which process internal energy remains constant ?
Ans: Isothermal process.
88. What is temper embrittlement in alloy steels and what are its effects ?
Ans: Embrittlement attack is usually intergranular in metals, i.e. cracks progress between the grains of the
polycrystalline material. It imparts a tendency to fail under a static load after a given period of time in those
alloy steels which are susceptible to embrittlement.
89. What are whiskers ?
Ans: Whiskers are very small crystals which are virtually free from imperfections and dislocations.
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24. 90. What is Bauschinger effect ?
Ans: According to Bauschinger, the limit of proportionality of material does not remain constant but varies
according to the direction of stress under cyclic stresses.
91. What is the difference between heat capacity and specific heat of a material ?
Ans: The heat capacity of a material is the amount of heat transformed to raise unit mass of a material 1
degree in temperature.
The specific heat of a material is the ratio of the amount of heat transferred to raise unit mass of a material1
degree in temperature to that required to raise unit mass of water 1 degree of temperature at some specified
temperature.
For most engineering purposes, heat capacities may be assumed numerically equal to;specific heats.
92. Explain the rule to find specific heat of aqueous solutions.
Ans: For aqueous solutions of salts, the specific heat can be estimated by assuming the specific heat of the
solution equal to that of the water alone. Thus, for a 15% by weight solution of sodium chloride in water, the
specific heat would be approximately 0.85.
93. Whatdoyouunderstandbylatentheat?Givefourexamplesoflatentheats.
Ans: For pure substances, the heat effects accompanying changes in state at constant pressure (no
temperature change being evident) are known as latent heats. Examples of latent heats are : heat of fusion,
vaporisation, sublimation, and change in crystal form.
94. Define the terms free energy and free enthalpy. What is their significance and importance?
Ans: Free energy (or Helmholtz function) is defined as/= u -Ts.
It is equal to the work during a constant-volume isothermal reversible nonflow process.
Free enthalpy (or Gibbs function) is defined as g = h – Ts
(where u = internal energy, h = enthalpy, T = temperature, s = entropy)
Gibbs function is of particular importance in processes where chemical changes occur. For reversible
isothermal steady-flow processes or for reversible constant-pressure isothermal nonflow processes, change
in free energy is equal to net work.
95.Which parameter remains constant in isochoric process ?
Ans: Volume.
96. What is polytropic process ? Under what conditions it approaches isobaric, isothermal, and isometric
process ? In which reversible process no work is done ?
Ans: A polytropic process is one that follows the equation pun = constant (index n may have values from –
oc to + oo. This process approaches isobaric when n = 0, isothermal when n = 1, and isometric when n =
<x>. No work is done in isometric process.
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25. 97. Whether superheated steam can be treated like ideal gas?
Ans: Yes.
98. Out of constant pressure and constant volume lines on TS diagram which line has higher slope ? And
whether slope is constant or variable?
Ans: Constant volume line. Slope is variable.
99. Whether entropy is intensive property or extensive property ?
Ans: Entropy is extensive property.
100. In which process fluid expands but does no work?
Ans: Throttling process.
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