This paper outlines the study of neutron stars right from the early
theoretical predictions and observations by various astrophysicists which
gradually aroused huge interests among the scientific community, to the
latest developments in the scientific analysis of the behavior of the different
categories of compact objects. Although white dwarfs, neutron stars, brown
dwarfs, Black Holes etc.fall under the category of compact objects, each of
them is unique in its own way.
Newton and his universal theory of universal gravitation. This Project explains what this theory is, how Newton proposed it and some other information about Isaac Newton.
We believe the quantum entanglement is caused by the very space itself, not by any particles, and thus not bounded by the speed of light, so is the gravity, we stand at fireworks side.
EMU M.Sc. Thesis Presentation
Thesis Title: "Dark Matter; Modification of f(R) or WIMPS Miracle"
Student: Ali Övgün
Supervisor: Prof. Dr. Mustafa Halilsoy
Slides from my presentation at the Joint CoEPP-CAASTRO Workshop (http://www.caastro.org/event/2013/coepp), 28 February 2013. Brief overview of the evidence for dark matter in the Universe, plus discussion of challenges, hints of possible signals, and some references for further reading.
The presentation time-slot was 30 minutes + 20 minutes discussion.
Newton and his universal theory of universal gravitation. This Project explains what this theory is, how Newton proposed it and some other information about Isaac Newton.
We believe the quantum entanglement is caused by the very space itself, not by any particles, and thus not bounded by the speed of light, so is the gravity, we stand at fireworks side.
EMU M.Sc. Thesis Presentation
Thesis Title: "Dark Matter; Modification of f(R) or WIMPS Miracle"
Student: Ali Övgün
Supervisor: Prof. Dr. Mustafa Halilsoy
Slides from my presentation at the Joint CoEPP-CAASTRO Workshop (http://www.caastro.org/event/2013/coepp), 28 February 2013. Brief overview of the evidence for dark matter in the Universe, plus discussion of challenges, hints of possible signals, and some references for further reading.
The presentation time-slot was 30 minutes + 20 minutes discussion.
Universe and the Solar System (Lesson 1).pptxJoenelRubino3
SHS Earth and Life Grade 11 Lesson 1. This lesson discusses the compos of the universe, the origin of the universe, different hypotheses of the origin of the universe
This power point presentation is created for Science 8 learners. This presentation tackles on the three sub atomic particles of atom, the one who discovers them, how do they discover them and the different atomic theory models.
The Evolution of Atomic Theory and The Models of the AtomMichaelDeniega2
This is a carefully crafted presentation about the progress of the atomic theory showcasing different atomic model introduced by famous scientists. This is one of the important concepts of discussion in Physical Science 11
Integration of Unified Power Quality Controller with DGIJRST Journal
This paper gives an insight into the analytical results of the intergration of Unified power quality controller (conditioner) with distribution generation system. The intergration is achieved by connecting the DClink throught rectifier to the distribution generatoion along with thwe connection of the series and shunt inverter to the same dc link. This type of connection can account for the voltage sag, voltage swell, along with the reduction of harmonics and also compensation of reactive power. The analysis is supported with the simulation which will are discussed in detail in the paper.
An Efficient User Privacy and Protecting Location Content in Location Based S...IJRST Journal
In location-based query a user wants to query a database of location data, known as Points Of Interest (POIs), and does not want to reveal his/her location to the server due to privacy concerns; (ii) the owner of the location data, that is, the location server, do Abstract: Nowadays, it is very easy for a person to learn his/her location with the help of a Global Positioning System (GPS) enabled device. A location s not want to simply distribute its data to all users. The location server desires to have some control over its data, since the data is its asset. A major enhancement upon previous solutions by introducing a two stage approach, the first step is based on Oblivious Transfer using homomorphic encryption and the second step is based on Private Information Retrieval, to achieve a secure solution for both parties. Introduce a security model and analyse the security in the context of our protocol. To highlight a security weakness of our previous work and present a solution using efficient homomorphic system.
A Particle Swarm Optimization for Optimal Reactive Power DispatchIJRST Journal
This paper presents particle swarm optimization (PSO) based approach for solving optimal reactive power dispatch for minimizing power losses. The control variables are bus voltage magnitudes (continuous type), transformer tap settings (discrete type) and reactive power generation of capacitor banks (discrete type). The algorithm solution of PSO is tested on a standard IEEE 30 Bus system. The intention is to minimize power losses by optimizing the reactive power dispatch with optimal setting of control variables without violating inequality constraints and satisfying equality constraint. The detailed results for different cases have been listed
A Novel Approach for Interference Suppression Using a Improved LMS Based Adap...IJRST Journal
A novel adaptive beam forming technique is proposed for wireless communication applications based on the minimum bit error rate (MBER) criterion known as LMS algorithm. LMS (Least Mean Square) algorithm is used for steering the antenna beam electronically. Using the Rectangular, Hamming, Kaiser, Chebyshev windows both the block-data and sample-by-sample adaptive implementations of the MBER solution are developed. By making use of window techniques half power beam width of an antenna is enhanced using Matlab simulation. The gain of the system will definitely improve the performance of CDMA based system, where the number of interferes is quite large and helps to increase the spectral efficiency of wireless communication systems. Any beam former that can depress the large number of interferers will improve the capacity and performance. Such beam formers are called smart antennas. They improve signal to interference ratio (SIR) of the communication system efficiently by forming narrow beam towards desired user and low side towards undesired users. Smart antennas offer a broad range of ways to improve wireless system performance.
Support Vector Machine for Wind Speed PredictionIJRST Journal
The energy is a vital input for the social and economic development of any nation. With increasing agricultural and industrial activities in the country, the demand for energy is also increasing. The increasing use of natural and renewable energy sources is needed to take the burden of our current dependency on fossil fuels. Development and analysis of renewable energy models helps utility in energy forecasting, planning, research and policy making. The wind power is a clean, inexhaustible, and almost a free source of energy. But the integration of wind parks with the power grid has resulted in many challenges for the utility in terms of commitment and control of power plants. As wind speed and wind direction fluctuate frequently, the accurate long-term and short-term forecasting of wind speed is important for ascertaining the wind power generation availability. To deal with wind speed forecasting, many methods have been developed such as physical method, which use lots of physical considerations to reach the best forecasting precision and other is the statistical method, which specializes in finding the relationship of the measured power data. Wind speed can be predicted by using time series analysis, artificial neural network, Kalman Filter method, linear prediction method, spatial correlation models and wavelet, also by using the support vector machines. In this paper, the SVM is used for day ahead prediction of wind speed using historical data of wind park. In this paper Support Vector Machine (SVM) results are compared with feedforward Backpropagation neural network. It is observed that the Mean Absolute Percentage Error (MAPE) by SVM method is around 7% and correlation coefficient is close to 1. This justifies the ability of SVM for wind speed prediction task than Backpropagation algorithm.
Performance Evaluation of Computationally Efficient Energy Detection Based Sp...IJRST Journal
The rapid growth of bandwidth demanding wireless technologies has led to the problem of spectrum scarcity. However, studies show that licensed spectrum is underutilized. Cognitive radio technology promises a solution to the problem by allowing unlicensed users, access to the licensed bands opportunistically. A prime component of the cognitive radio technology is spectrum sensing. Many spectrum sensing techniques have been developed to sense the presence or not of a licensed user. This paper evaluates the performance of the energy detection based spectrum sensing technique in noisy, fading, jamming, interference environments. Both single user detection and cooperative detection situations were investigated. Closed form solutions for the probabilities of detection and false alarm were derived. The analytical results were varied by numerical computations using Monte Carlo method with MATLAB. The performance of the computationally efficient energy detection (CE-ED) techniques were evaluated by use of Receiver Operating Characteristics (ROC) curves over additive white Gaussian noise (AWGN) and fading (Rayleigh & Nakagami-m) channels. Results show that for single user detection, the energy detection technique performs better in AWGN channel than in the fading channel models. The performance of cooperative detection is better than single user detection in fading environments.
The Internet of Things (IoT), also referred to as the Internet of Objects, will change everything—including ourselves. This may seem like a bold statement, but consider the impact the Internet already had on education, science, communication, business, government, and humanity. Clearly, the Internet is one of the most important and a powerful creation in all of human history. This paper discussesIOT architecture, IOT applications and limitations of IOT.
Reduction of Frequency offset Using Joint Clock for OFDM Based Cellular Syste...IJRST Journal
This project addresses the problem of clock synchronization between a base station (BS) and a mobile station (MS). A conventional technique for clock synchronization is that the MS clock is derived from the downlink signal originated from a base station. In cellular systems, a base station and mobile stations need to be synchronized before data exchange. Since the base station clock reference is more accurate, a mobile station typically derives its clock reference from the base station. But the carrier frequency offset due to Doppler shift may have harmful effects on the local clock derivation. This project proposes a joint clock and frequency synchronization technique between a base station and a mobile station, which is effective even with Doppler shift. We derive the joint estimation algorithm by analyzing the phase and the amplitude distortion caused by the sampling frequency offset and the carrier frequency offset. Simulation results showing the effectiveness of the proposed algorithm will also be presented.
Analysis of Voltage and Current Variations in Hybrid Power SystemIJRST Journal
In this paper, a detailed dynamic model and simulation of a solar cell/wind turbine/fuel cell hybrid power system is Developed using a novel topology to complement each other and to alleviate the effects of environmental variations. Comparing with the nuclear energy and thermal power, the renewable energy is inexhaustible and has non-pollution Characteristics. Here Ultra-capacitors are used in power applications requiring short duration peak power. The voltage variation at the output is found to be within the acceptable range. The output fluctuations of the wind turbine varying with wind speed and the solar cell varying with both environmental temperature and sun radiation are reduced using a fuel cell. Therefore, this system can tolerate the rapid changes in load and environmental conditions, and suppress the effects of these fluctuations on the equipment side voltage. The proposed system can be used for off-grid power generation in non interconnected areas or remote isolated communities. Modeling and simulations are conducted using MATLAB/Simulink software packages to verify the effectiveness of the proposed system. The results show that the proposed hybrid power system can tolerate the rapid changes in natural conditions and suppress the effects of these fluctuations on the voltage within the acceptable range.
DTC Scheme for a Four-Switch Inverter-Fed PMBLDC Motor Emulating the Six-Swit...IJRST Journal
The paper deals with the direct torque control (DTC) of brushless DC (BLDC) motor drives fed by four-switch three phase inverters (FSTPI) rather than six-switch inverters (SSTPI) in conventional drives. For any three phase inverter require six switches, but these switches are reduced to four. This reduction of power switches from six to four improves the reliability of the inverter, size of the inverter is reduced and cost of the inverter is also reduces. The FSTPI could be regarded as a reconfigured topology of the SSTPI in case of a switch/leg failure which represents a crucial reliability benefit for many applications especially in electric and hybrid propulsion systems. The DTC of FSTPI-fed BLDC motor drives is treated considering two strategies, such as: 1) DTC-1: a strategy inspired from the one intended to SSTPI-fed BLDC motor drives; 2) DTC-2: a strategy that considers a dedicated vector selection subtable in order to independently control the torques developed by the phases connected to the FSTPI legs during their simultaneous conduction. The operational principle of the four-switch BLDC motor drive and the developed control scheme are theoretically analyzed and the performance is demonstrated by simulation.
A Compact Remote Switching With Efficient Monitoring For AC PlantsIJRST Journal
Remote monitoring has been implemented in many areas. This paper
introduces its specific application to air-conditioning plant control and
monitoring using PIC Microcontroller. Remote monitoring and intelligent
maintenance is one of the most important criteria for maximizing production
and process plant availability. Initially switching and monitoring were done
through manually and the control switches and level monitoring unit were
placed at separate places. Due to this, we cannot monitor all units at a time. In
our proposed system, remote switching and monitoring is done in the control
room itself. Majority of industries use distributed control system for high
reliability, improve response time, improved operator interface to plant,
improved accessibility of plant data.
Reactive Power Compensation in Distribution Network with Slide Mode MPPT Cont...IJRST Journal
The Grid connected PV system requires a proper voltage control controller.
In this paper an efficient voltage control by using slide mode controller with
Maximum Power Point Tracking (MPPT) is presented. The voltage
command is determined by the PV panel. Here the sliding mode controller is
designed so as to balance the power flow from PV panel to the grid and load
such that the PV power is utilized effectively. The design and simulation
using MATLAB is presented in this work.
Power Quality Improvement by UPQC based on Voltage Source ConvertersIJRST Journal
In modern power system consists of wide range of electrical, electronic and power electronic equipment in commercial and industrial applications. Since most of the electronic equipment’s are nonlinear in nature these will induce harmonics in the system, which affect the sensitive loads to be fed from the system. These problems are partially solved with the help of LC passive filters. However, this kind of filter cannot solve random variation in the load current wave form and voltage wave form. Active filters can resolve this problem. However, the cost of active filters is high. They are difficult to implement in large scale. Additionally, they also present lower efficiency than shunt passive filters. One of the many solutions is the use of a combined system of shunt and active series filters like Unified Power Quality Conditioner (UPQC) which aims at achieving a low cost under highly effective control. The UPQC device combines a shunt active filter together with a series active filter in a back-to-back configuration, to simultaneously compensate the supply voltage and the load current or to mitigate any type of voltage and current fluctuations and power factor correction in a power distribution network, such that improved power quality can be made available at the point of common coupling. The control strategies are modeled using MATLAB/SIMULINK. The performance is also observed under influence of utility side disturbances such as harmonics and voltage sags. The simulation results are compared without and with UPQC for the verification of results.
Detection of DNA Damage Using Comet Assay Image AnalysisIJRST Journal
Reactive species such as free radicals are constantly produced in vivo and DNA is the very important target of oxidative stress. Oxidative DNA damage is considered as a predictive biomarker to monitor the risk of development of many diseases. The comet assay is widely used for specifying oxidative DNA damage at a single cell level. The analysis of comet assay output images, however, poses considerable challenges. The comet assay, also known as single-cell gel electrophoresis (SCGE), is a simple, sensitive and reliable method for studying DNA damage caused by physical and chemical agents. So the comet assay is a well-established, simple, versatile, visual, rapid, and sensitive method used extensively to assess DNA damage quantitatively and qualitatively at single cell level. The comet assay is most frequently used to analyze white blood cells or lymphocytes in human bio monitoring studies. So through the analysis of comet assay image we can detect edge of damaged DNA comet isolating it from undamaged DNA.
Review of Step down Converter with Efficient ZVS OperationIJRST Journal
This paper presents the review of step down converter with efficient ZVS operation. The designed buck converter uses ZCS technique and the function is realized so that the power form is converted from 12V DC 5V DC (1A). A detailed analysis of zero current switching buck converters is performed and a mathematical analysis of the mode of operation is also presented. In order to reduce the switching losses in associated with conventional converters; resonant inductor and resonant capacitor (LC resonant circuit) is applied which helps to turn on-off the switch at zero current. The dc-dc buck converter receives the energy from the input source, when the switch is turned-on. The buck–buck converters have characteristics that warrant a more detailed study. The buck converters under discontinuous conduction mode /continuous conduction mode boundary.
Review of Reduction of Leakage Current in Cascaded Multilevel InverterIJRST Journal
Multilevel inverters are a source of high power, often used in industrial applications and can use either sine or modified sine waves. A multilevel inverter uses a series of semiconductor power converters (usually two to three) thus generating higher voltage. Reverse leakage current in a semiconductor device is the current from that semiconductor device when the device is reverse biased. In earlier method transformer is used for generating multilevel output and grid synchronization. Transformer increases the leakage current. Now transformerless method and sine modulation techniques are presented to reduce the leakage current.
A Study of SEPIC Converter Based Fuzzy Logic Controller For Hybrid SystemIJRST Journal
This paper presents the study of integrated hybrid renewable energy system. The wind and solar are used as input sources for the hybrid system. The proposed system involves the design of photovoltaic (PV) and wind energy conversion system (WECS).The system is designed for constant wind speed and varying solar irradiation and insolation. Maximum power point tracking (MPPT) algorithm is used to extract the maximum power from PV array. The integration of two input sources is done by single-ended primary-inductor converter. Fuzzy logic controller is used to control the duty cycle of one of the converter switch thereby extracting the maximum power from solar array. The system consists of photovoltaic (PV) array, wind energy conversion system (WECS), single-ended primary-inductor converter, voltage source inverter (VSI), LC filter and three phase load.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
#vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore#blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #blackmagicforlove #blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #Amilbabainuk #amilbabainspain #amilbabaindubai #Amilbabainnorway #amilbabainkrachi #amilbabainlahore #amilbabaingujranwalan #amilbabainislamabad
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
2. 2 International Journal of Research in Science & Technology
NEUTRON STARS - UNIQUE COMPACT OBJECTS OF THEIR OWN
B. The Prediction of Zwicky and Baade
The actual theoretical prediction of neutron stars was
made by W. Baade of Mount Wilson Observatory and F.
Zwicky of Caltech, who had analyzed the various
observations of supernova explosions and proposed an
explanations of the release of enormous energy in these
explosions. The results were presented at the meeting of the
„American Physical Society „at Stanford ( Dec 15-16 1933)
and was Published in the January issue of the Physical
Review ( Baade and Zwicky, 1934a). They had written “With
all reserve, we advance the view that the supernovae
represent the transitions from ordinary stars to neutron stars
which consist of extremely closely packed neutrons in their
final stages.”
In the next publication, Baade and Zwicky (1934b)
further elaborated that “a neutron star ....may possess a very
small radius and an extremely high density. As neutrons can
be packed much more closely than ordinary nuclei and
electrons, the gravitational packing energy in a cold neutron
star may become very large and under certain circumstances
may exceed the ordinary nuclear packing fractions. In the
consecutive paper (Baade and Zwicky, 1934c), they had
stated the transition process of an ordinary star into a neutron
star as follows: “If neutrons are produced on the surface of an
ordinary star, they will rain down towards the center, if we
assume that the light pressure on neutrons is practically
zero”.
C. Theoretical progress during the Pre - 2nd
world war era
( a) Development of Equation of State : The most crucial
ingredient of the theory of neutron stars is the „ Equation of
State „ ( EOS) of densely packed matter in the interiors of a
neutron star. EOS is often referred to the dependence of the
pressure p and linear mass density ρ and temperature T of the
matter. Since neutron stars are mainly composed of strongly
degenerate Fermions (particles like protons, electrons
etc..Which obey Fermi- Dirac Statistics), the temperature
dependence is mostly negligible and the equation of state is
calculated at T=O.
When an ordinary star transforms to a neutron
star, the stellar matter undergoes strong compression force,
which are further accompanied by the generation of neutrons
from the beta captures of atomic nuclei. A preliminary
attempt to construct the EOS of nuclear matter in equilibrium
was made by Sterne in 1933. He considered the matter
composed of electrons, protons, several species of nuclei at
T-> 0. He had actually predicted the neutronization of matter
with increasing density.
Interest in neutron stars aroused during
1937-38 mainly due to the problem of stellar energy with the
source of energybeing unknown. Landau (1937) and Gamow
(1938) had independently suggested that any normal star
could contain a neutron star in its core region. This certainly
would have initiated a slow „ accretion „ of stellar matter
within the normal star unto its neutron star core, so that the
stellar energy would have been supplied by the gravitational
energy release in the course of accretion. However Hans
Bethe and Critchfield in 1938 proved that the energy of
normal stars is provided by thermonuclear reactions.
Now in a paper (1938), Zwicky estimated the
maximum binding energy of a neutron star of mass M and
obtained as 0.42 M c
2
. One must certainly distinguish
between the so called Baryon mass (the sum of baryon masses
in the interior of a neutron star) and gravitational mass M
obtained from Baryon mass by subtracting the gravitational
binding energy. Zwicky (1938) also noticed that on the
surface of the star “ ....the acceleration of gravity should be
indeed high and light coming from this surface must be
subjected to huge gravitational red shifts ( of wavelengths). “
he later developed the idea of red shifts in a subsequent paper
elaborately” ( Zwicky 1939).
The next most important step was done by
Richard C. Tolman from Caltech and by Robert
Oppenheimer and G.M. Volkoff from university of
California, Berkeley. Their papers (Tolman 1939;
Oppenheimer and Volkoff, 1939) had been received in the
Physical Review on January 3rd
1939 and were published in
the same February issue. Both the papers contained the
mathematical derivation of the equation of Hydro-static
equilibrium for a spherically symmetric star in the
framework of General relativity. This was the basic equation
for building up the different models of neutron stars. It is
popularly known as “ Tolman - Oppenheimer - Volkoff “
equation. The gravitational neutron star energy is a sizeable
fraction of its rest mass energy; neutron stars are so compact
that Space- Time is curved around and the effects of General
Relativity play a significant role.
Tolman (1939) had obtained eight exact solutions
of the new equation. They do not correspond to any realistic
EOS of the neutron star matter, although they enable one
(Oppenheimer & Volkoff, 1939) to understand the existence
of a maximum mass of neutron stars. Oppenheimer &
Volkoff (1939) used their equation for solving the most
important problem. They had numerically calculated various
neutron star models for the simplest EOS of stellar matter
composed of a non interacting strongly degenerate
relativistic gas of neutrons. They had showed that stable
static neutron stars have the maximum (gravitational)
mass, which is nearly 0.71 times the mass of Sun, which is
popularly known as Oppenheimer- Volkoff mass limit.
They had understood the simplicity of their model of non
interacting neutrons and discussed a possible repulsive
component of neutron-neutron interaction which might
stiffen the EOS and thereby increase the maximum mass.
They concluded “It seems likely that our limit of 0.71 solar
masses is near the truth.” their conclusion has turned out to
be wrong, although their mass limit is extremely important.
Combined with accurate measured masses (1.25 - 1.44) times
mass of the sun, of some neutron stars, this limit gives a
direct astrophysical evidence of strong repulsive interaction
in dense matter at supra-nuclear density.
It is really worth mentioning that Von Neumann
3. 3 International Journal of Research in Science & Technology
Volume: 2 | Issue: 3 | March 2015 | ISSN: 2349-0845IJRST
and Chandrasekhar had obtained the same General
Relativistic equation of hydro-static equilibrium several
years before in 1934 to study collapsed stars, but their results
were not published ( Baym, 1982). This was done at the
Trinity College (Cambridge, England) after Chandrasekhar
had constructed models of white dwarf stars. More realistic
Equations of state could not be worked out during the Pre 2nd
world war time, because the properties of strong interactions
and nuclear matter were poorly known. The theoretical basis
was supplemented by the idea that neutron stars should be
born in supernova explosions. With the outbreak of the 2nd
world war however, interest in neutron stars gradually faded.
D. Theoretical progress during the Post 2nd world war
era
Until the beginning of the 1960s, neutron stars had been
treated as the work of imagination of some weird
theoreticians. The situation started changing later, with the
hope to discover neutron stars in observations. Let us outline
four main themes of theoretical studies.
(a) EOS of Dense matter: The main field of neutron
star theory prior to the discovery was concerned about
constructing a model EOS of dense stellar matter. Wheeler
and his collaborators in the 1950s contributed significantly.
They had constructed a model of the crust of a neutron star
and calculated the EOS of neutron star cores composed of
free neutrons, protons and electrons in beta equilibrium. It
was Cameron (1959) who emphasized the utmost
significance of nuclear forces for the structure of neutron
stars. He also had shown that the inclusion of nuclear forces
can certainly stiffen EOS. This can increase the maximum
mass of neutron stars from the Oppenheimer-Volkoff limit of
0.7 solar masses to about 2 solar masses, making the
formation of neutron stars in Supernova explosions more
realistic. Zeldovich in 1961 used a model of Baryon
interaction through a massive vector field and constructed a
stiff EOS with the sound speed lower than the speed of light
c, and tending to c in the extreme high density limit.
Eventually, it was understood that besides neutrons, protons,
electrons the cores of neutron stars might contain particles
such as muons, mesons, hyperons etc. The First arguments
regarding hyperons was put forward by Cameron (1959) and
Salpeter (1960); some EOS s of hyperonic matter and
associated neutron star models were calculated by several
authors like Ambartsumyan & Saakyan (1960) and Tsuruta
& Cameron (1966b). Ivanenko & Kurdgelaidze (1965, 1969)
considered hypothetical quark cores of neutron stars.
(b) Super-fluidity of neutron star matter: Another
striking aspect was the theoretical prediction of
Super-fluidity in the interiors of neutron stars. This was
actually initiated by the BCS theory of Superconductivity of
metals (Bardeen, Cooper and Schrieffer -1957). The electron
Superconductivityis explained by cooper pairing of electrons
under a weak attraction force which is induced by electron -
phonon interaction. A Superconducting state appears with
decreasing temperature as a result of a second order phase
transition; the typical critical temperatures being of the order
of (1-10) K. On a microscopic scale, the phenomenon
consists in the appearance of an energy gap Δ in the electron
energy spectrum near the Fermi level. Migdal (1959) was
one of the first persons who applied the BCS theory to atomic
nuclei. He had also remarked that neutron Super fluidity
could occur in the interiors of neutron stars; he predicted the
Super fluid gap Δ ~ 1 MeV and the associated critical
temperature Tc ~ 10
10
Kelvin. Five years later Ginzburg
and Kirzhnits (1964) estimated the gap produced by the
singlet state pairing of neutrons at the densities of nearly
10
13
- 10
15
g / cm
3
and obtained Δ~ (5- 20) MeV. A serious
step was also made by Wolf (1966) in this regard. He showed
that the singlet state neutron pairing operates at sub nuclear
densities in the inner neutron star crust, but disappears in the
core, since the singlet state neutron-neutron interaction
becomes highly repulsive at supra nuclear densities. The
number density of protons in the core is smaller than that of
neutrons. Accordingly, the singlet state proton- proton
interaction is mostly attractive there and it leads to proton
pairing. The possibility of neutron pairing in the core of the
neutron star due to the attractive part of the triplet state
neutron-neutron interaction was understood quite later.
It is thought that Super fluidity is quite important for
explaining pulsar glitches. It also affects the heat capacity
and neutrino emission of neutron stars. The effect of neutron
Super- fluidity on the neutrino emission was first studied by
Wolf (1966).
(c) Emission of neutrinos from Neutron stars:
Another line of theoretical studies was inspired by the
expectations at the beginning of the 1960s to discover
neutron stars by detecting the thermal radiation from their
surfaces. Born hot in Supernova explosions, neuron stars get
cooled down by the thermal emission of photons from stellar
surfaces and the emission of neutrinos from their interiors.
This certainlymakes the neutrino processes quite significant.
In this regard, we must mention a paper by Chiu & Salpeter
(1964) who had suggested the modified Urca process and
estimated the emissivity of neutrinos. It is the leading
neutrino process in the cores of not too massive neutron stars.
The detailed calculations were performed particularly by
Bahcall and Wolf (1965a). They also studied a model of
dense matter which contains free Pions. They had also
considered the neutrino process which consists of two
reactions; neutron beta decay followed by beta capture in the
presence of Pions. The neutrino emissivity appeared to be
much higher than in the modified Urca process. Similar
enhancement in a more realistic model of Pion- Condensed
matter was analyzed much later by Maxwell et al. (1977).
More references to earlier papers on the neutrino emission
from neutron stars can be found in Yakovlev et al. (2001).
(d) Thermal Evolution of Neutron stars: The first
estimates of the thermal emission from cooling neutron stars
were most probably done by Stabler (1960). Four years later
Chiu (1964) repeated the estimates and theoretically proved
the possibility to discover neutron stars from their thermal
4. 4 International Journal of Research in Science & Technology
NEUTRON STARS - UNIQUE COMPACT OBJECTS OF THEIR OWN
emission. Simplified calculations of the neutron star cooling
were done by Morton (1964), Chiu & Salpeter (1964) and
Bahcall & Wolf (1965a, b). The latter authors emphasized
the strong dependence of the cooling rate on neutrino
emission processes and pointed out that this dependence can
be used to explore the EOS of dense matter by comparing
theoretical cooling models with observations of thermal
radiation from neutron stars. The foundation of the strict
cooling theory was made by Tsuruta & Cameron (1966a).
They had formulated the main elements of the cooling theory
such as the neutrino and photon cooling stages, the relation
between the internal and surface temperatures. More detailed
description of the history of the neutron star cooling is given
by Yakovlev et al. (1999).
III. THE SEARCH AND THE DISCOVERY
Serious attempts were made to discover neutron stars
when the era of practical X - ray astronomy began in the
1960s. It was expected to detect the thermal radiation from
the surfaces of cooling neutron stars. A star with the surface
temperature of ~ 10
6
K would mainly emit soft X- rays which
cannot be detected by ground based facilities.
The first Cosmic X- ray source of non solar origin, Sco
X-1 (in the Scorpius constellation), was discovered in rocket
experiments by Giacconi et al...(1962). The discovery
generated a huge interest in neutron stars but the first
attempts had failed to prove the relation between neutron
stars and newlydiscovered compact X-raysources. Bowyer et
al (1964) measured the size of the X ray source in the crab
nebula from observations during a lunar occultation on July
7, 1964. Their result indicated that the source was much
larger than a neutron star should be. Ironically, the crab
nebula turned out to be an exception: there was a neutron star
there, the famous Crab Nebula, but it was hidden within a
compact plerion pulsar Nebula. The Crab Nebula is actually
the archetype of a plerion - a supernova remnant with an
active pulsar at its centre, powering the nebula expansion and
radiation. At the same time, Kardashev (1964) considered a
collapse of a magnetized rotating star into a compact object
(collapsar) with the appearance of a surrounding envelope
(nebula). He emphasized that the collapsar can gain rapid
rotation during its birth and its spin energy can be transferred
to the surrounding nebula by the magnetic field. He assumed
that this mechanism can power the crab Nebula.
Many scientists proposed various methods of
discovering neutron stars ( as described by Zeldovich &
Novikov 1971, Shapiro & Teukolsky 1983 and Lyne &
Graham Smith 1998). For instance, Zeldovich & Guseynov
(1966) suggested observing some selected binary stars with
optical primary components and invisible secondary
components. Pacini (1967) , in a paper published in Nature,
showed that a rapidly rotating neutron star with a strong
dipole magnetic field could efficiently transform its
rotational energy into electromagnetic radiation and
subsequently accelerate particles to high energies. He
suggested that the rotational energy loss rate is the same as
produced by a magnetic dipole rotating in vacuum. Like
Kardashev, he anticipated that such a star could obviously
power a surrounding nebula, particularly the crab nebula.
It was quite important that Sandage et al. (1966) had
identified Sco X-1, the first detected and the brightest X – ray
source as an optical object of 13th
magnitude. Analyzing
those observations, Scklovsky (1967) had concluded that the
source “…. Corresponds to a neutron star in a state of
accretion …and…..the natural and very efficient supply of
gas for such a accretion is a stream of gas, which flows from
a secondary component of a close binary system toward the
primary component which is a neutron star”. Now, we know
that Sco X-1 is indeed an X-ray binary system consisting of
an accreting neutron star, but Shklovsky‟s arguments were
mostly ignored by the astrophysical community. In 1965
Antony Hewish (Cavendish laboratory, Cambridge,
England) started to construct a new radio telescope. Its
wavelength was 3.7m; it was an array of 2048 dipole
antennae that covered an area of about 18,000 square meters.
It was designed to study the scintillations of radio sources
while their radiation passes through in homogeneities of
solar wind in the interplanetary space. On August 6th
, 1967,
Jocelyn Bell – a graduate student supervised by Hewish since
1965 discovered a weak variable radio source (Hewish 1975).
It was observed at night time, whereas the scintillations of
ordinary radio sources are stronger at day time, when a
telescope is directed closer to the sun. it took several weeks to
understand that the rapidly spinning or pulsating source, the
pulsar was well outside the solar system. The discovery was
announced on 24th
February 1968 issue of Nature (Hewish et
al. ...1968) and produced a sensation. White dwarf stars
could not sustain such a rapid rotation; they would be
destroyed by centrifugal forces. Hence, pulsars are spinning
neutron stars with their magnetic moments inclined to spin
axes. Their radio emission is generated outside a star, in the
magnetosphere. It is beamed along the magnetic axis. The
beamed radiation rotates with the star, and a pulsar is
detected if its beam crosses the Earth. The emitted
electromagnetic radiation carries away the rotational energy
and momentum, producing a slow but regular spinning down
of the pulsar which results in the increase of the pulse period.
IV. CONCLUSION
The Neutron stars certainly prove themselves to be unique
of their kind generating huge interests in the scientific
community with respect to the magnetic fields, pulsations,
emission of electromagnetic radiation etc…The internal core
processes are still quite complicated and lots of phenomena
need to be understood in this regard. Super fluidity plays a
key role in understanding the interiors of compact objects.
ACKNOWLEDGMENT
I am highly indebted to Prof. Dr. Christian Corda,
Astrophysicist, Prato, Florence, Italy who is the inspiration
5. 5 International Journal of Research in Science & Technology
Volume: 2 | Issue: 3 | March 2015 | ISSN: 2349-0845IJRST
for my work. I am also highly grateful to Prof. Dr. B.G.
Sidharth, Director, BM Birla Science centre, Hyderabad,
India for his valuable support and motivation. I
wholeheartedly acknowledge Prof. Dr. Herman Mosquera
cuesta, Astrophysicist Brazil for his extensive support and
encouragement.
REFERENCES
[1] J. M. Lattimer and M. Prakash, "Neutron Star Structure and the Equation
of State" Astrophysical J. 550(1) 426
(2001); http://arxiv.org/abs/astro-ph/0002232
[2] Baade, Walter and Zwicky, Fritz (1934). "Remarks on Super-Novae and
Cosmic Rays". Phys. Rev. 46 (1):
76–77. Bibcode:1934PhRv...46...76B.doi:10.1103/PhysRev.46.76.2
[3] Landau L.D. (1932). "On the theory of stars". Phys. Z. Sowjetunion 1:
285–288.
[4] P. Haensel, A. Y. Potekhin, & D. G. Yakovlev (2007).Neutron Stars 1:
Equation of State and Structure (New York: Springer), page
2http://adsabs.harvard.edu/abs/2007ASSL..326.....H
[5] Chadwick, James (1932). "On the possible existence of a
neutron". Nature 129 (3252):
312.Bibcode:1932Natur.129Q.312C.doi:10.1038/129312a0
[6] Hewish and Okoye; Okoye, S. E. (1965). "Evidence of an unusual source
of high radio brightness temperature in the Crab
Nebula". Nature 207 (4992): 59.Bibcode:1965Natur.207...59H
[7] Shklovsky, I.S. (April 1967). "On the Nature of the Source of X-Ray
Emission of SCO XR-1". Astrophys. J.148 (1):
L1–L4. Bibcode:1967ApJ...148L...1S.doi:10.1086/180001.
[8] Alpar, M Ali (January 1, 1998). "Pulsars, glitches and superfluids"
[9] Compact Stellar X-ray Sources (2006). Eds. Lewin and van der Klis,
Cambridge University
[10] J. M. Lattimer and M. Prakash, "Neutron Star Structure and the Equation
of State" Astrophysical J. 550(1) 426
(2001); http://arxiv.org/abs/astro-ph/0002232
[11] Baade, W.; Zwicky, F. (1934). "On Super-Novae". Proceedings of the
National Academy of Sciences 20 (5):
254–9.Bibcode:1934PNAS...20..254B. doi:10.1073/pnas.20.5.254. PM
C 1076395. PMID 16587881
[12] Sandin, F. (2005). "Compact stars in the standard model – and
beyond". European Physical Journal C 40:
15.arXiv:astro-ph/0410407. Bibcode:2005EPJC...40...15S. doi:10.114
0/epjcd/s2005-03-003-y
[13] Neutron Stars 1, Equation of State and structure – P. Haensel, A.Y.
Potekhin and D.G. Yakolev, 2007 Springer series. ISBN -10:
0-387-33543-9 ISBN-13: 978-0-387-33543-8 ( ASTROPHYSICS
AND SPACE SCIENCE LIBRARY ASSL)