Mathematical Modeling of Cylindrical Dielectric Resonator Antenna for Applica...IJERA Editor
We are moving forward in an era where adaptive antenna arrays will be capable of identifying the direction of the incoming signal and steering the transmitted beam in appropriate directions. It has already been proposed that Dielectric Resonator Antennas (DRAs) can be good candidates for such applications. In this paper, we have carefully analyzed the theoretical model of a DRA and have proposed various mathematical methods for its analysis. The methods proposed herein can reduce the complexity of analysis and design of circuits involving DRAs.
Breve presentazione Wikimania Esino Lario 2016 in italianoIolanda Pensa
Breve presentazione Wikimania Esino Lario 2016 in italiano. Wikimania – il raduno mondiale di Wikipedia e Wikimedia – sarà nel 2016 a Esino Lario in Provincia di Lecco in Lombardia. La prima volta in Italia, la prima volta sulle Alpi, la prima volta in un piccolo paese di montagna.
Mathematical Modeling of Cylindrical Dielectric Resonator Antenna for Applica...IJERA Editor
We are moving forward in an era where adaptive antenna arrays will be capable of identifying the direction of the incoming signal and steering the transmitted beam in appropriate directions. It has already been proposed that Dielectric Resonator Antennas (DRAs) can be good candidates for such applications. In this paper, we have carefully analyzed the theoretical model of a DRA and have proposed various mathematical methods for its analysis. The methods proposed herein can reduce the complexity of analysis and design of circuits involving DRAs.
Breve presentazione Wikimania Esino Lario 2016 in italianoIolanda Pensa
Breve presentazione Wikimania Esino Lario 2016 in italiano. Wikimania – il raduno mondiale di Wikipedia e Wikimedia – sarà nel 2016 a Esino Lario in Provincia di Lecco in Lombardia. La prima volta in Italia, la prima volta sulle Alpi, la prima volta in un piccolo paese di montagna.
Ternary Content Addressable Memory Types And Matchline SchemesIJERA Editor
Ternary Content Addressable Memory (TCAM) used in many application like network routers and packet classification. To reduce the power consumption of matchlines, the matchline partitioning scheme is used. Matchline is partitioned into NOR and NAND type matchline. If NAND (NOR) type TCAM cell is used then NAND (NOR) type matchline is used. NOR type TCAM has feature of high speed and high compare power. NAND type TCAM has low speed and low compare power. The NAND and NOR type matchlines are combined to form the pai-sigma matchlines. In pai segment the NAND type cells are connected in parallel to form the NAND type matchline. In sigma segment NOR type cells are connected in series to form the NOR type matchline. When compare operation is performed all NAND type matchlines are activated because switching power is low. Based on the match result of the NAND matchlines the NOR matchlines are activated because of high speed. The matchline incurs the problem of short circuit current due to mismatch and match result of NAND and NOR matchlines. NAND type matchline exist the problem of charge sharing when the search result of the NAND line is mismatches. This proposed TCAM has less compare (search) power compared to the NAND/NOR type TCAM cell.
Fabrication of aluminum foam from aluminum scrapIJERA Editor
In this study the optimum parameters affecting the preparation of aluminum foam from recycled aluminum were studied, these parameters are: temperature, CaCO3 to aluminum scrap wt. ratio as foaming agent, Al2O3 to aluminum scrap wt. ratio as thickening agent, and stirring time. The results show that, the optimum parameters are the temperature ranged from 800 to 850oC, CaCO3 to aluminum scrap wt. ratio was 5%, Al2O3 to aluminum scrap wt. ratio was 3% and stirring time was 45 second with stirring speed 1200 rpm. The produced foam apparent densities ranged from 0.40-0.60 g/cm3. The microstructure of aluminum foam was examined by using SEM, EDX and XRD, the results show that, the aluminum pores were uniformly distributed along the all matrices and the cell walls covered by thin oxide film.
Analysis, Design and Application of Continuously Variable Transmission (CVT)IJERA Editor
Continuously Variable Transmission (CVT) offers a continuum of gear ratios between desired limits. This allows the engine to operate more time in the optimum range. In contrast, traditional automatic and manual transmissions have several fixed transmission ratios forcing the engine to operate outside the optimum range. The need for a transmission system and the working principle of CVT has been discussed in depth. An attempt has been made to understand the contribution of Hydraulic Actuators, which is an integral part of a CVT. Furthermore, the question of how and why a Torque Converter has effectively replaced a conventional clutch has been answered. The materials used, constructional aspects and stress analysis of the belt has been discussed in detail. A graphical comparison of fuel efficiency between a manual transmission and a CVT in different high end vehicles is included. Recent developments in clamping force control for the push belt Continuously Variable Transmission (CVT) have resulted in increased efficiency in combination with improved robustness. Current control strategies attempt to prevent macro slip between elements and pulleys at all times for maximum robustness.
Due to technological advances, vast data sets (e.g. big data) are increasing now days. Big Data a new term; is used
to identify the collected datasets. But due to their large size and complexity, we cannot manage with our current
methodologies or data mining software tools to extract those datasets. Such datasets provide us with unparalleled
opportunities for modelling and predicting of future with new challenges. So as an awareness of this and
weaknesses as well as the possibilities of these large data sets, are necessary to forecast the future. Today’s we
have an overwhelming growth of data in terms of volume, velocity and variety on web. Moreover this, from a
security and privacy views, both area have an unpredictable growth. So Big Data challenge is becoming one of the
most exciting opportunities for researchers in upcoming years.
Hence this paper discuss about this topic in a broad overview like; its current status; controversy; and challenges to
forecast the future. This paper defines at some of these problems, using illustrations with applications from various
areas. Finally this paper discuss secure management and privacy of big data as one of essential issues.
Investigating On Use of Different Blends of White Grape Seed Biodiesel and Di...IJERA Editor
Diesel engine is an internal combustion engine which has made life easy and faster in today's modern life. These engines are consuming lot of diesel fuel and have been substantially increasing the atmospheric pollution. There is a concern over the availability of diesel fuel a derivative of fossil fuel, as these sources are limited and in near future they may get exhausted. Hence, there is a need for an alternative source of fuel which is abundant and environmentally friendly. A promising renewable and clean burning diesel replacement is biodiesel fuel. This is an alternative fuel made by different methods like standard base-catalysed transesterification, pyrolysis, thermal cracking etc., An alternative method called catalytic cracking, a fast reaction process is investigated for production of quantitative and qualitative biodiesel. Among many available catalysts, alumina catalyst is selected for production of biodiesel. Catalytic cracking process is carried out on white grape seed oil to convert it into white grape seed biodiesel. On production of biodiesel, physicochemical properties are tested and compared with diesel. Biodiesel thus obtained is a very near quality diesel fuel as per ASTM standards this can be used in the existing diesel engines. Experimental work is carried out on a single cylinder [Kirloskar TV-1 (DI), Water cooled, 4-Stroke] diesel engine with diesel fuel and also with biodiesel blended in various proportions with diesel at different engine loads. On analysis, it is inferred that there is a minimal deviation in engine characteristics with white grape seed biodiesel and with its blends when compared to characteristics of engine fueled with diesel. This gives a scope for further research to be carried out with other catalysts to produce biodiesel with different vegetable or animal fat based oils.
Comparative Study of Manual Lubrication and Automatic LubricationIJERA Editor
Lubrication is the process or technique employed to reduce the wear of one or both surface in close proximity. Most of the bear lubrication fail due to the too much or too less grease injected using manual lubrication. So, to replace the manual lubrication discrete wiring employed in lubrication system in heavy machines using PLC. The PLC’s can be used to overcome the shortcomings PLC is mainly used to reduce the labor cost, power consumption, complication in circuits.
A Review and study of the design technique of Microstrip Patch Antenna Techno...IJERA Editor
In this paper,study and survey of microstrip antenna elements is presented, with emphasis on theoretical and
practical design techniques and material used, as previous study have been proved that material used play
significant role in the performance such as gain ,directivity ,frequency of radiation Available substrate materials
are reviewed along with the relation between dielectric constant tolerance and resonant frequency of microstrip
patches. Several theoretical analysis techniques are summarized. Practical procedures are given for both
standard rectangular and circular patches. The quality, bandwidth, and efficiency factors of typical patch designs
are discussed.
Condition Monitoring and Vibrational Analysis of Proposed Shaft through Exper...IJERA Editor
Condition Monitoring is an advanced and very useful tool of predictive maintenance techniques.When a
machine fails or break down, the consequences can range from annoyance to the financial disaster or personal
injury and possible loose of life. For this reason early detection, identification and correction of machinery
problems is paramount to anyone involved in the maintenance of industrial machinery to insure continued, safe
and productive operation. In order to run the machines efficiently condition monitoring of machines is
important.Vibrations are found almost everywhere in rotating shaft. shaft vibrates due to unbalances,
misalignments and imperfect bearings. .Here in this project condition monitoring of rotating shaft is done using
vibration analysis and also crack detection analysis, accelerometeris used along with a device called as Fast
Fourier Transform (F.F.T.) Analyzer.
Assessment of Water Quality of Lakes for Drinking and Irrigation Purposes in ...IJERA Editor
Lake water is an important source for drinking, domestic and irrigation purposes in rural and urban India. The present study aims at evaluating the water quality of various lakes in Raipur city, Chhatisgarh. There existed 154 lakes in the city but it shrinked to 85 in number due to encroachment or drying up of lakes. Twenty seven prominent lakes are selected to study and evaluate the water quality for drinking and irrigation purposes. The water samples were collected and analysed for pH, Turbidity, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Alkalinity, Hardness, Sodium(Na+), Potassium(K+), Calcium(Ca2+), Magnesium(Mg2+), Bicarbonate(HCO3-), Sulphate (SO42-), Nitrate (NO3−),Phosphate(PO43-) Fluoride(F-), Chloride (Cl−), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Dissolved Oxygen (DO), Total Coliform (TC) and Fecal Coliform (FC). There are variations for pH (6.59-8.29), EC (382-2330μS/cm), Turbidity (1-232 NTU), TDS (244-1491 mg/L), Alkalinity (120-600 mg/L), Hardness (66-330mg/L), Na+(37-430 mg/L), K+ (8-253 mg/L), Ca2+ (9-90 mg/L), Mg2+(3-26 mg/L), SO42- (5-200 mg/L), NO3-(0-19 mg/L), PO43-(0.19-5.3 mg/L), F-(0.18-1.41 mg/L) and Cl- (46-388 mg/L), DO(1-8.6 mg/L), BOD (0.1-11.3 mg/L), COD (8-118 mg/L), Total Coliform( 15-3600 MPN/100ml) and Fecal Coliform (4-240 MPN/100 ml). The results have been compared with the drinking water standard prescribed by Bureau of Indian Standard (BIS). All the physiochemical parameters are within the prescribed limit except turbidity, fecal & total coliform. The Sodium Adsorption Ratio (SAR) and salinity hazards are studied to classify the water for irrigation uses. It is found that lake water is suitable for irrigation purposes.
A Geographical Distribution of Aids Cases in Tamilnadu District Wise (2008 – ...IJERA Editor
The present study was undertaken to characterize the various opportunistic pathogens (fungi and bacteria) which are responsible for high morbidity and mortality in 25 HIV seropositive patients, either hospitalized (5 Nos) (or) coming to antiretroviral therapy centre in Government hospital, TamilNadu, were included in the study for finding the spectrum of opportunistic pathogens. Blood serum, urine, sputum, and oral swabs were collected and processed. A total of eight pathogens were detected.
Power dissipation has emerged an important parameter in design of Low Power CMOS circuits. For this level
converter and dual supply voltage assignments are used to reduce the power dissipation and propagation delay.
In this paper, variable supply-voltage scheme (dual-VS scheme) for dual power supplies along with voltage
level converter is presented. Also paper presents an overall comparative analysis among various methods to
achieve voltage level shifter even in lower technology comparative to higher ones and help user to select the
best methods for same at this technology.
Effect of Solvent Swelling on the reactivity of demineralized Turkish LigniteIJERA Editor
In this research, effect of demineralization and solvent swelling on pyrolysis kinetics was investigated. The experiments were carried out to investigate theeffects of solvent swelling with different solvents, such as THF, Pyridine and DMSO after demineralization with HCl, HNO3 and HF successively. To calculate the activation energies of lignite sample during pyrolysis, TGA analyses were performed with raw and swollen samples at 5, 10 and 20° C/min heating rates. Coast-Redfernmodel was used for the determination of kinetic parameters. According to the results, the macromolecular structure of lignite was affected from these hydrogen bonding solvents. So, the activation energies of swollen samples found to be less than the raw lignite sample for all heating rates. The reactivity of lignite samples can be ordered as follows; DMSO swollen sample > Pyridine swollen sample> THF swollen sample. Activation energy of DMSO swollen lignite sample is 10.62 kJ/mole whereas activation energies of pyridine swollen and THF swollen sample are 17.83, 25.76 kJ/mol, respectively at a heating rate of 10° C/min. The results indicated that, solvent swelling has catalytic effect on pyrolysis kinetics.
Analysing The Composite Structure Of Riverted ,Hybrid And Bonded JointsIJERA Editor
Composite materials have been widely used as structural elements in aircraft structures due to their superior
properties. Aircraft structure is a huge assembly of skins, spars, frames etc. The structure consists of an
assembly of sub-structures properly arranged and connected to form a load transmission path. Such load
transmission path is achieved using joints. Joints constitute the weakest zones in the structure. Failure may occur
due to various reasons such as stress concentrations, excessive deflections etc. or a combination of these.
Therefore, to utilize the full potential of composite materials, the strength and stress distribution in the joints has
to be understood so that suitable configuration can be chosen for various applications
Ternary Content Addressable Memory Types And Matchline SchemesIJERA Editor
Ternary Content Addressable Memory (TCAM) used in many application like network routers and packet classification. To reduce the power consumption of matchlines, the matchline partitioning scheme is used. Matchline is partitioned into NOR and NAND type matchline. If NAND (NOR) type TCAM cell is used then NAND (NOR) type matchline is used. NOR type TCAM has feature of high speed and high compare power. NAND type TCAM has low speed and low compare power. The NAND and NOR type matchlines are combined to form the pai-sigma matchlines. In pai segment the NAND type cells are connected in parallel to form the NAND type matchline. In sigma segment NOR type cells are connected in series to form the NOR type matchline. When compare operation is performed all NAND type matchlines are activated because switching power is low. Based on the match result of the NAND matchlines the NOR matchlines are activated because of high speed. The matchline incurs the problem of short circuit current due to mismatch and match result of NAND and NOR matchlines. NAND type matchline exist the problem of charge sharing when the search result of the NAND line is mismatches. This proposed TCAM has less compare (search) power compared to the NAND/NOR type TCAM cell.
Fabrication of aluminum foam from aluminum scrapIJERA Editor
In this study the optimum parameters affecting the preparation of aluminum foam from recycled aluminum were studied, these parameters are: temperature, CaCO3 to aluminum scrap wt. ratio as foaming agent, Al2O3 to aluminum scrap wt. ratio as thickening agent, and stirring time. The results show that, the optimum parameters are the temperature ranged from 800 to 850oC, CaCO3 to aluminum scrap wt. ratio was 5%, Al2O3 to aluminum scrap wt. ratio was 3% and stirring time was 45 second with stirring speed 1200 rpm. The produced foam apparent densities ranged from 0.40-0.60 g/cm3. The microstructure of aluminum foam was examined by using SEM, EDX and XRD, the results show that, the aluminum pores were uniformly distributed along the all matrices and the cell walls covered by thin oxide film.
Analysis, Design and Application of Continuously Variable Transmission (CVT)IJERA Editor
Continuously Variable Transmission (CVT) offers a continuum of gear ratios between desired limits. This allows the engine to operate more time in the optimum range. In contrast, traditional automatic and manual transmissions have several fixed transmission ratios forcing the engine to operate outside the optimum range. The need for a transmission system and the working principle of CVT has been discussed in depth. An attempt has been made to understand the contribution of Hydraulic Actuators, which is an integral part of a CVT. Furthermore, the question of how and why a Torque Converter has effectively replaced a conventional clutch has been answered. The materials used, constructional aspects and stress analysis of the belt has been discussed in detail. A graphical comparison of fuel efficiency between a manual transmission and a CVT in different high end vehicles is included. Recent developments in clamping force control for the push belt Continuously Variable Transmission (CVT) have resulted in increased efficiency in combination with improved robustness. Current control strategies attempt to prevent macro slip between elements and pulleys at all times for maximum robustness.
Due to technological advances, vast data sets (e.g. big data) are increasing now days. Big Data a new term; is used
to identify the collected datasets. But due to their large size and complexity, we cannot manage with our current
methodologies or data mining software tools to extract those datasets. Such datasets provide us with unparalleled
opportunities for modelling and predicting of future with new challenges. So as an awareness of this and
weaknesses as well as the possibilities of these large data sets, are necessary to forecast the future. Today’s we
have an overwhelming growth of data in terms of volume, velocity and variety on web. Moreover this, from a
security and privacy views, both area have an unpredictable growth. So Big Data challenge is becoming one of the
most exciting opportunities for researchers in upcoming years.
Hence this paper discuss about this topic in a broad overview like; its current status; controversy; and challenges to
forecast the future. This paper defines at some of these problems, using illustrations with applications from various
areas. Finally this paper discuss secure management and privacy of big data as one of essential issues.
Investigating On Use of Different Blends of White Grape Seed Biodiesel and Di...IJERA Editor
Diesel engine is an internal combustion engine which has made life easy and faster in today's modern life. These engines are consuming lot of diesel fuel and have been substantially increasing the atmospheric pollution. There is a concern over the availability of diesel fuel a derivative of fossil fuel, as these sources are limited and in near future they may get exhausted. Hence, there is a need for an alternative source of fuel which is abundant and environmentally friendly. A promising renewable and clean burning diesel replacement is biodiesel fuel. This is an alternative fuel made by different methods like standard base-catalysed transesterification, pyrolysis, thermal cracking etc., An alternative method called catalytic cracking, a fast reaction process is investigated for production of quantitative and qualitative biodiesel. Among many available catalysts, alumina catalyst is selected for production of biodiesel. Catalytic cracking process is carried out on white grape seed oil to convert it into white grape seed biodiesel. On production of biodiesel, physicochemical properties are tested and compared with diesel. Biodiesel thus obtained is a very near quality diesel fuel as per ASTM standards this can be used in the existing diesel engines. Experimental work is carried out on a single cylinder [Kirloskar TV-1 (DI), Water cooled, 4-Stroke] diesel engine with diesel fuel and also with biodiesel blended in various proportions with diesel at different engine loads. On analysis, it is inferred that there is a minimal deviation in engine characteristics with white grape seed biodiesel and with its blends when compared to characteristics of engine fueled with diesel. This gives a scope for further research to be carried out with other catalysts to produce biodiesel with different vegetable or animal fat based oils.
Comparative Study of Manual Lubrication and Automatic LubricationIJERA Editor
Lubrication is the process or technique employed to reduce the wear of one or both surface in close proximity. Most of the bear lubrication fail due to the too much or too less grease injected using manual lubrication. So, to replace the manual lubrication discrete wiring employed in lubrication system in heavy machines using PLC. The PLC’s can be used to overcome the shortcomings PLC is mainly used to reduce the labor cost, power consumption, complication in circuits.
A Review and study of the design technique of Microstrip Patch Antenna Techno...IJERA Editor
In this paper,study and survey of microstrip antenna elements is presented, with emphasis on theoretical and
practical design techniques and material used, as previous study have been proved that material used play
significant role in the performance such as gain ,directivity ,frequency of radiation Available substrate materials
are reviewed along with the relation between dielectric constant tolerance and resonant frequency of microstrip
patches. Several theoretical analysis techniques are summarized. Practical procedures are given for both
standard rectangular and circular patches. The quality, bandwidth, and efficiency factors of typical patch designs
are discussed.
Condition Monitoring and Vibrational Analysis of Proposed Shaft through Exper...IJERA Editor
Condition Monitoring is an advanced and very useful tool of predictive maintenance techniques.When a
machine fails or break down, the consequences can range from annoyance to the financial disaster or personal
injury and possible loose of life. For this reason early detection, identification and correction of machinery
problems is paramount to anyone involved in the maintenance of industrial machinery to insure continued, safe
and productive operation. In order to run the machines efficiently condition monitoring of machines is
important.Vibrations are found almost everywhere in rotating shaft. shaft vibrates due to unbalances,
misalignments and imperfect bearings. .Here in this project condition monitoring of rotating shaft is done using
vibration analysis and also crack detection analysis, accelerometeris used along with a device called as Fast
Fourier Transform (F.F.T.) Analyzer.
Assessment of Water Quality of Lakes for Drinking and Irrigation Purposes in ...IJERA Editor
Lake water is an important source for drinking, domestic and irrigation purposes in rural and urban India. The present study aims at evaluating the water quality of various lakes in Raipur city, Chhatisgarh. There existed 154 lakes in the city but it shrinked to 85 in number due to encroachment or drying up of lakes. Twenty seven prominent lakes are selected to study and evaluate the water quality for drinking and irrigation purposes. The water samples were collected and analysed for pH, Turbidity, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Alkalinity, Hardness, Sodium(Na+), Potassium(K+), Calcium(Ca2+), Magnesium(Mg2+), Bicarbonate(HCO3-), Sulphate (SO42-), Nitrate (NO3−),Phosphate(PO43-) Fluoride(F-), Chloride (Cl−), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Dissolved Oxygen (DO), Total Coliform (TC) and Fecal Coliform (FC). There are variations for pH (6.59-8.29), EC (382-2330μS/cm), Turbidity (1-232 NTU), TDS (244-1491 mg/L), Alkalinity (120-600 mg/L), Hardness (66-330mg/L), Na+(37-430 mg/L), K+ (8-253 mg/L), Ca2+ (9-90 mg/L), Mg2+(3-26 mg/L), SO42- (5-200 mg/L), NO3-(0-19 mg/L), PO43-(0.19-5.3 mg/L), F-(0.18-1.41 mg/L) and Cl- (46-388 mg/L), DO(1-8.6 mg/L), BOD (0.1-11.3 mg/L), COD (8-118 mg/L), Total Coliform( 15-3600 MPN/100ml) and Fecal Coliform (4-240 MPN/100 ml). The results have been compared with the drinking water standard prescribed by Bureau of Indian Standard (BIS). All the physiochemical parameters are within the prescribed limit except turbidity, fecal & total coliform. The Sodium Adsorption Ratio (SAR) and salinity hazards are studied to classify the water for irrigation uses. It is found that lake water is suitable for irrigation purposes.
A Geographical Distribution of Aids Cases in Tamilnadu District Wise (2008 – ...IJERA Editor
The present study was undertaken to characterize the various opportunistic pathogens (fungi and bacteria) which are responsible for high morbidity and mortality in 25 HIV seropositive patients, either hospitalized (5 Nos) (or) coming to antiretroviral therapy centre in Government hospital, TamilNadu, were included in the study for finding the spectrum of opportunistic pathogens. Blood serum, urine, sputum, and oral swabs were collected and processed. A total of eight pathogens were detected.
Power dissipation has emerged an important parameter in design of Low Power CMOS circuits. For this level
converter and dual supply voltage assignments are used to reduce the power dissipation and propagation delay.
In this paper, variable supply-voltage scheme (dual-VS scheme) for dual power supplies along with voltage
level converter is presented. Also paper presents an overall comparative analysis among various methods to
achieve voltage level shifter even in lower technology comparative to higher ones and help user to select the
best methods for same at this technology.
Effect of Solvent Swelling on the reactivity of demineralized Turkish LigniteIJERA Editor
In this research, effect of demineralization and solvent swelling on pyrolysis kinetics was investigated. The experiments were carried out to investigate theeffects of solvent swelling with different solvents, such as THF, Pyridine and DMSO after demineralization with HCl, HNO3 and HF successively. To calculate the activation energies of lignite sample during pyrolysis, TGA analyses were performed with raw and swollen samples at 5, 10 and 20° C/min heating rates. Coast-Redfernmodel was used for the determination of kinetic parameters. According to the results, the macromolecular structure of lignite was affected from these hydrogen bonding solvents. So, the activation energies of swollen samples found to be less than the raw lignite sample for all heating rates. The reactivity of lignite samples can be ordered as follows; DMSO swollen sample > Pyridine swollen sample> THF swollen sample. Activation energy of DMSO swollen lignite sample is 10.62 kJ/mole whereas activation energies of pyridine swollen and THF swollen sample are 17.83, 25.76 kJ/mol, respectively at a heating rate of 10° C/min. The results indicated that, solvent swelling has catalytic effect on pyrolysis kinetics.
Analysing The Composite Structure Of Riverted ,Hybrid And Bonded JointsIJERA Editor
Composite materials have been widely used as structural elements in aircraft structures due to their superior
properties. Aircraft structure is a huge assembly of skins, spars, frames etc. The structure consists of an
assembly of sub-structures properly arranged and connected to form a load transmission path. Such load
transmission path is achieved using joints. Joints constitute the weakest zones in the structure. Failure may occur
due to various reasons such as stress concentrations, excessive deflections etc. or a combination of these.
Therefore, to utilize the full potential of composite materials, the strength and stress distribution in the joints has
to be understood so that suitable configuration can be chosen for various applications
2. Huiswerkbespreking
• Zijn er nog vragen over de
huiswerkopgaven?
• (par. 14.3: 3, 5, 7, 10, 15, 17, 23, 41, 47,
53, 62, 73, 77 )
3. Doelen
• Bij functies van twee of meer variabelen:
• Paragraaf 14.7: Het vinden van maxima en
minima bij functies van twee variabelen.
4. Maxima en minima bij functies van
één variabele.
• Uit paragraaf 4.3:
• Als 𝑓′
𝑐 = 0 en 𝑓′′
0 = 0, dan kunnen we
nog geen uitspraak doen: bijvoorbeeld:
• 𝑓(𝑥) = 𝑥3 en 𝑔(𝑥) = 𝑥4, dan is 𝑓′
𝑥 =
𝑓′′
0 = 0 en ook 𝑔′
0 = 𝑔′′
0 = 0, terwijl
𝑓 geen minimum heeft in x=0 en 𝑔 wel.
5. Maxima en minima
• We zien dus dat het nodig
is dat de partiële
afgeleiden nul zijn, maar
dit is niet (altijd) genoeg.
7. Maxima en minima (3)
• Het geval dat D=0 is vergelijkbaar met
functies van één variabele: als 𝑓′
𝑥 =
0 en 𝑓′′
𝑥 = 0 moeten we meer
onderzoek doen.
• Dus als D=0 is er nog geen duidelijkheid.
9. Zadelvlak
• Dus als 𝑓 𝑥, 𝑦 = 𝑥2
− 𝑦2
, dan is 𝑓 𝑥 𝑥, 𝑦 =
2𝑥 en 𝑓𝑦 𝑥, 𝑦 = −2𝑦, dus 𝑓𝑥 0,0 =
𝑓𝑦 0,0 = 0.
• Verder is 𝑓 𝑥𝑥 𝑥, 𝑦 = 2, 𝑓𝑥𝑦 𝑥, 𝑦 =
𝑓𝑦𝑥 𝑥, 𝑦 = 0 en 𝑓𝑦𝑦 𝑥, 𝑦 = −2.
• Dus is D=-4: we hebben dus met een
zadelpunt van doen.
11. Extrema op een gesloten vlakdeel
(met rand).
• Opmerking: hier wordt D voor een vlakdeel
gebruikt (dat gesloten is: d.w.z. de rand hoort
er ook bij). Dat is anders dan hiervoor.
15. Opgaven (3): kies er één.
Opmerking: Bij opg. 53 is het bewijs dat het
daadwerkelijk een maximum is erg bewerkelijk.
16. Opgaven en huiswerk.
week Boek
6 §14.7 m.u.v. Proof of Theorem
3 (blz. 953)
Opgaven
3, 6, 7,13 (*),15, 17, 31, 35, 39, 43, 51
(*): 7 en 13 in plaats van 15 en 17 (vanwege veel
rekenwerk in 15 en 17)