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September 10th, 2014 Comments off
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A Novel Scheme to Eliminate Common Mode Voltage in Multilevel Inverters

August 9th, 2014 Comments off
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Electrical Power Generation Using Piezoelectric Crystal

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1 INTRODUCTION

echanical stresses applied to piezoelectric materials distort internal dipole moments and generate elec- trical potentials (voltages) in direct proportion to the applied forces. These same crystalline materials also lengthen or shorten in direct proportion to the magnitude and polarity of applied electric fields.
Because of these properties, these materials have long been used as sensors and actuators. One of the earliest practical applications of piezoelectric materials was the development of the first SONAR system in 1917 by Lan- gevin who used quartz to transmit and receive ultrasonic waves [1]. In 1921, Cady first proposed the use of quartz to control the resonant frequency of oscillators. Today, piezoelectric sensors (e.g., force, pressure, acceleration) and actuators (e.g., ultrasonic, micro positioning) are widely available.
The same properties that make these materials useful for sensors can also be utilized to generate electricity. Such materials are capable of converting the mechanical energy of compression into electrical energy, but developing pie- zoelectric generators is challenging because of their poor source characteristics (high voltage, low current, high impedance). This is especially true at low frequencies and relatively low power output.
These challenges have limited the use of such generators primarily because the relatively small amount of available regulated electrical power has not been useful. The recent advent of extremely low power electrical and mechanical devices (e.g., micro electromechanical systems or MEMS) makes such generators attractive in several applications where remote power is required. Such applications are sometimes referred to as power scavenging and include in vivo sensors, embedded MEMS devices, and distributed networking.

Several recent studies have investigated piezoelectric power generation. One study used lead zirconate titanate (PZT) wafers and flexible, multilayer polyvinylidene fluoride (PVDF) films inside shoes to convert mechanical walking energy into usable electrical energy [2], [3]. This system has been proposed for mobile computing and was ultimately able to provide continuously 1.3 mW at 3 V when walking at a rate of 0.8 Hz. Other projects have used piezoelectric films to extract electrical energy from mechanical vibration in machines to power MEMS devices [4]. This work extracted a very small amount of power (<5uW) from the vibration and no attempt was made to condition or store the energy. Simi- lar work has extracted slightly more energy (70uW) from
machine and building vibrations [5].
Piezoelectric materials have also been studied to generate electricity from pressure variations in micro hydraulic systems [6]. The power would presumably be used for MEMS but this work is still in the conceptual phase. Other work has used piezoelectric materials to convert kinetic energy into a spark to detonate an explosive projectile on impact [7]. Still other work has proposed using flexible piezoelectric polymers for energy conversion in wind- mills [8], and to convert flowin oceans and rivers into electric power [9].A recent medical application has pro- posed the use of piezoelectric materials to generate elec-
tricity to promote bone growth [10]. This work uses an implanted bone prosthesis containing a piezoelectric ge- nerator configured to deliver electric current to specific locations around the implant. This device uses unregu- lated (high voltage) energy and it is not clear if the tech- nique has advanced beyond the conceptual phase. The above studies have all had some success in extracting electrical power from piezoelectric elements. However, many issues such as efficiency, conditioning and storage have not been fully addressed.
This paper presents the idea to increase the power gener- ation by the piezoelectric. A few researchers have used single off the-shelf piezoelectric devices to harvest elec- trical power, yet little has been done to overcome the main weaknesses associated with piezoelectric power harvest- ing. This research seeks to systematically overcome the weaknesses associated with cantilever-mounted piezoelec- tric used for mobile power harvesting to maximize the power from a piezoelectric device the load impedance must match the impedance of device. This is problematic for frequencies between 10-100 Hz because a single pie- zoelectric may have impedance in the range of several hundred thousand ohms to ten million ohms. Thus, little current can be produced, and battery charging is dimi- nished due to low current production. To reduce the im- pedance and increase electrical current, two off-the-shelf actuators (8 piezoelectric totals) are connected electrically in parallel and tuned to resonate in the frequency range of an ambient vibration similar to that produced by a person walking. A picture of the experimental setup may be seen in Figure 1.

Click to read more about journal- http://www.ijser.org/onlineResearchPaperViewer.aspx?Electrical_Power_Generation_Using_Piezoelectric_Crystal.pdf

Categories: 2011 Editorials Tags:

Molecular Biocoding of Insulin – Amino Acid Gly

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1 INTRODUCTION

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A number of atoms in the relevant amino acids, The biologic role of any given protein in essential life processes, eg, insulin, depends on the positioning of its component amino acids, and is understood by the „positioning of letters forming words“. Each of these words has its biochemical base. If this base is expressed by corresponding discrete numbers, it can be seen that any given base has its own program, along with its own unique cybernetics and information characteristics.
Indeed, the sequencing of the molecule is determined not only by distin biochemical features, but also by cybernetic and information principles. For this reason, research in this field deals more with the quantitative rather than qualitative characteristcs of genetic information and its biochemical basis. For the purposes of this paper, specific physical and chemical factors have been selected in order to express the genetic information for insulin.Numerical values are them assigned to these factors, enabling them to be measured. In this way it is possible to determine oif a connection really exists between the quantitative ratios in the process of transfer of genetic information and the qualitative appearance of the insulin molecule. To select these factors, preference is given to classical physical and chemical parameters, including the their analog values, the position in these amino acids in the peptide chain, and their frenquencies.There is a arge numbers of these parameters, and each of their gives important genetic information. Going through this process, it becomes clear that there is a mathematical relationship between quantitative ratios and the qualitative appearance of the biochemical ,genetic processes“ and that there is a measurement method that can be used to describe the biochemistry of insulin.

2 METHODS

Insulin can be represented by two different forms, ie, a discrete form and a sequential form. In the discrete form, a molecule of insulin is represented by a set of discrete codes or a multiple dimension vector. In the sequential form, an insulin molecule is represent by a series of amino acids according to the order of their position in the chains 1AI0.
Therefore, the sequential form can naturally reflect all the information about the sequence order and lenght of an insulin molecule. The key issue is whether we can develop a different discrete method of representing an insulin molecule that will allow accomodation of partial, if not all sequence order information? Because a protein sequence is usually represented by a series of amino acids should be assigned to these codes in order to optimally convert the sequence order information into a series of numbers for the discrete form representation?

Click to read more about journal- http://www.ijser.org/onlineResearchPaperViewer.aspx?Molecular_Biocoding_of_Insulin-Amino_Acid_Gly.pdf

Categories: 2011 Editorials Tags:

Face Recognition using Neural Network and Eigenvalues with Distinct Block Processing

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I. INTRODUCTION

THE face is our primary focus of attention in social intercourse, playing a major role in conveying identity and emotion. Although the ability to infer intelligence or character from facial appearance is suspect, the human ability to recognize faces is remarkable. We can recognize thousands of human faces[1,2,3] learned throughout our lifetime and identify familiar faces at a glance even after years of separation. This skill is quite robust, despite large changes in the visual stimulus due to viewing conditions, expression, aging, and distractions such as glasses or change in hairstyle or facial hair. As a consequence, the visual processing of human faces has fascinated philosophers and scientists for centuries.
Computational models of face recognition [5,7,8,9,10,11], in particular, are interesting because they can contribute not only to theoretical insights but also to practical applications. Computers that recognize faces could be applied to a wide variety of problems, including criminal identifications, security systems, image and film processing and human – computer interaction. For example, the ability to model a particular face and distinguish it from a large number of stored face models would make it vastly improve criminal identification. Even the ability to merely detect faces, as opposed to recognizing them can be important. Detecting faces in photographs[20], for instance, is an important problem in automating color film development, since the effect of many enhancement and noise reduction techniques depends on the picture content.
Unfortunately, developing a computational model of face recognition is quite difficult, because faces are complex, multidimensional and meaningful visual stimuli. Thus unlike most early visual functions, for which we may construct detailed models[28] of retinal or striate activity, face recognition is a very high level task for which computational approaches can currently only suggest broad constraints on the corresponding neural activity.
We, therefore, focused my paper towards implementing a sort of early, pre-attentive pattern recognition[11,42] capability that does not depend on having three-dimensional information or detailed geometry. Our goal is to develop a computational model of face recognition which would be fast, reasonably simple, and accurate in constrained environments such as an office or a household. In addition, the approach is biologically implementable and in concern with preliminary findings in the physiology and psychology of face recognition. The scheme is based on an information theory approach that decomposes face images into a small set of characteristics feature images called “eigenfaces”[12,23,24,34,36], which may be through of as the principal components of the initial training set of face images. Recognition is performed by projecting a new image into the subspace spanned by the eigenfaces (“face space”) and then classifying the face by comparing its position in face space with the positions of known individuals.

Click to read more about journal- http://www.ijser.org/onlineResearchPaperViewer.aspx?Face_Recognition_using_Neural_Network_and_Eigenvalues_with_Distinct_Block_Processing.pdf

Implementing Anti Collision Algorithm for Multiple Tag Identification

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1 INTRODUCTION

RFID (Radio Frequency Identification) is a technology that deciphers or identifies the tag information through a reader (or interrogator) without contact. RFID have become very popular in many service indus- tries, purchasing and distribution logistics, industry, manufacturing companies and material flow systems. Automatic Identification procedures exist to provide in- formation about people, animals, goods and products in transit [1],[2].
The reader receives required information from the tags by sending and receiving wireless signals with the tag. Since the communication between the readers and the tags shares wireless channels, there exist collisions. The collisions can be divided into the reader collision and the tag collision. The reader collision occurs when multiple readers send request signals to one tag, and the tag rece- ives the wrong request signal due to signal interference between readers. The tag collision occurs when more than two tags simultaneously respond to one reader and the reader cannot identify any tags. This kind of collision makes the reader take long time to identify tags within the reader’s identification range and impossible to identi- fy even one tag [3]- [6].
Therefore, the collision is a crucial problem that must be resolved in RFID systems, so many studies to resolve this problem have been carried out as well as are ongoing.
This paper focuses on the tag collision problem which occurs in the case where one reader identifies multiple tags. A design methodology is implemented in reader and tag module to avoid collision problem and an anti- collision algorithm is implemented in RFID reader .

2 RFID SYSTEM FOR MULTIPLE TAG IDENTIFICATION

RFID systems typically use small, low-cost, battery free devices called TAGs, which use the radio signal from a specialised RFID reader for power and communication. When queried, each TAG responds with a unique identi- fication number by reflecting energy back to the reader with a technique called backscatter modulation. Usually TAGs are application specific, fixed function devices that have an operating range of 10–50 cm for inductively coupled devices and 3–10 m for UHF TAGs. Traditional- ly, RFID TAGs have been used as a replacement for bar- codes in applications such as supply-chain monitoring, asset management, and building security [8].
When multiple tags are present in readers interroga- tion area,all tags try to access the reader at a time as a result the reader cannot notify a single tag or take long time for identification as shown in fig[1]

Fig 1: Tag collision problem in RFID system

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Behavior of Eight Bus System with TC-IPC

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1 INTRODUCTION

The basic operating requirements of an AC power system are that the synchronous generators must remain in synchronism and the voltages must be kept close to their rated values. The capability of a power system to meet these requirements in the face of possible disturbance is characterized by its transient (or first swing), dynamic (or power oscilla- tion), and voltage stability. Transient stability may be defined as the ability of an electric power system to remain in synchronism after being subjected to a major system disturbance (such as a short circuit). Accord- ing to equal-area criteria transient stability of a pow- er system is maintained if the accelerating area equals the decelerating area during the first rotor swing following the fault clearance.
To avoid stability problems a fast power flow con- trol within the first swing of the generator is re- quired. This can be achieved by different means, such as high performance excitation systems and high ceiling voltage, breaking resistors usage, superconducting magnetic energy storage systems and etc.
The recent availability of solid-state power switching devices with controlled turn off capability has made possible further advances in power con- version and control, leading to the development of a new generation of FACTS devices. FACTS (Flexi- ble AC Transmission Systems) devices, as discussed in references , are first of all, effective tools for dy- namic power flow control. On the other hand power flow is clearly related to a system‘s transient stability problems. As a result FACTS devices,
such as UPFC (Unified Power Flow Controller), SPS (Static Phase Shifting Transformers) , CSC (Controlled Series Compensator) , are presented as an effective tool to mitigate transient stability problems in electric power systems. These devices are power electronic based controllers, which can influence transmission system voltages, currents, influence transmission sys- tem voltages, currents, impedances and/or phase angle rapidly. Thus FACTS devices (or controllers) can improve both the security and flexibility of a pow- er system. This paper presents the capability of IPC (Interphase Power Controller) as a mean for power stability improvement. Concerning this matter, it is necessary to replace the conventional PST (Phase Shifting Transformer) with the static PST (SPS). The result of these changes is a new FACTS device, which is referenced to it as Thyristor Controlled IPC or TC-IPC

2 INTRODUCTION TO IPC

One of the problems for interconnected power sys- tems is overrating of circuit breakers and associated substation equipment due to short circuit level. Con- ventional options to decrease the short circuit levels are splitting existing bus into two or more sections, addition of series reactors in transmission lines and using transformers with high impedance or replacing over-duty substation circuit breakers and associated equipments. However, none of the above methods provide additional transmission capability or ability to control and redirect the power flow.
Splitting an existing bus into more than one section decreases the substation fault problem in a relatively costeffective manner, but operating flexibility and re- liability will be decreased. In practice, it may be diffi- cult to obtain permission to change the existing bus configuration. Series reactors can neither completely eliminate the fault current contributions nor efficiently reduce the transmission constraints. At normal condi- tions, series reactors absorb reactive power. Under heavy loading conditions, this solution can make more problems for voltage regulation. Replacing the under- rated circuit breakers and associated substation equipments with higher interrupting devices, is anoth- er method to overcome the fault duty problem . De- pending on voltage levels, the number of circuit break- ers involved and desired new rating for the breakers, the replacement of breakers can be expensive. In addi- tion, scheduling large number of circuit breaker re- placements imposes planning and engineering chal- lenges.
Some new techniques for fault limitation such as se- ries compensation, flexible alternative current trans- mission systems (FACTS), phase shifting transformer (PST) or Inter phase Power Controller (IPC) in an exist- ing substation can be very attractive options. In the present thesis, the role of IPC is discussed .

Click to read more about journal- http://www.ijser.org/onlineResearchPaperViewer.aspx?Behavior_of_Eight_Bus_System_with_TC-IPC.pdf

Design and Development of Fault Tolerent Control system for an Infant Incubator

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1 INTRODUCTION

THE objective of a fault tolerant control system (FTCS) is to maintain system availability when fault occurs, to improve the reliability of the control system and to minimize the effects on the system performance and safe- ty [1].
Fault is a kind of malfunction in the system, which may lead to system degradation or any unaccepta- ble performance of the system. The output of the Sensor should be constrained between the lower and upper lim- its, if it crosses these bounds then it is said that the senor is failed.
Fault tolerant control (FTC) has been increasing in the last few years because FTC system has the ability to increase complex systems reliability and performance requirement in the events of faults. The design of a FTC system requires knowledge of advanced control mechan- ism [3]. Systems mostly are very complicated. Designing a FTC system could also be very challenging. Different types of faults such as actuators, sensors, and system faults can occur. Each type of fault requires different ap- proach to work with. A fault tolerant control system must be able to perform, fault detection, fault isolation, and fault diagnosis [3]. FTC should also have the ability to detect faults and provide correction. Fault tolerant control system results on two approaches: active and passive. The active approach relies on fault detection and isolation (FDI) scheme to detect the occurrence of faults in the sys

tem and to identify the source and severity of the faults. Secondly, in passive FTC, potential component faults are known a prior and are all taken into consideration in the control system design stage [5].
Infant incubator provides a controlled environment for newborns needing special care, such as those born prema- turely. By placing an infant in an incubator, doctors and nurses can set and monitor different aspects of the child’s environment in order to create ideal conditions for sur- vival and moreover it protect infants from pollutants and infection[2].
This paper proposes the design and development of microcontroller based temperature and humidity con- troller for an infant incubator monitors and controls these two parameters constantly which are very critical for the normal growth of the new born (premature) babies. Infant incubator is used mainly to keep a baby’s care tempera- ture stable at 37 Celsius and the relative humidity is maintained at (45 to 55)%RH.This system can automati- cally control the infant’s temperature at optimum level and to maintain high relative humidity so as to minimize the thermal loss. The developed system must be user friendly, cost effective and accurate.

2 SENSOR FAULT TOLERANT CONTROL SYSTEM

Infant incubators and other advances in medical tech- nology have made it possible for small or premature ba- bies to survive in higher numbers than they did in the middle of the 20th century. An incubator is an infant- stimulating system used for intensive care of the new born, premature or sick baby. It provides a safe and clean environment, which has fresh air, clean and sterile ambient conditions for the babies. In addition to these, the incubator environment provides a homogeneous and sta- ble temperature, a relative humidity (RH) level that are needed especially for intensive care of the premature ba- by.

Click to read more about journal- http://www.ijser.org/onlineResearchPaperViewer.aspx?Design_and_Development_of_Fault_Tolerent_Control_system_for_an_Infant_Incubator.pdf

Tidal Power: An Effective Method of Generating Power

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1 INTRODUCTION

TIDAL power, also called tidal energy, is a form of hydropower that converts the energy of tides into electricity or other useful forms of power. The first large-scale tidal power plant (the Rance Tidal Power Station) started operation in 1966.
Although not yet widely used, tidal power has potential for future electricity generation. Tides are more predictable than wind energy and solar power. Among sources of renewable energy, tidal power has traditionally suffered from relatively high cost and limited availability of sites with sufficiently high tidal ranges or flow veloci- ties, thus constricting its total availability. However, many recent technological developments and improve- ments, both in design (e.g. dynamic tidal power, tidal lagoons) and turbine technology (e.g. new axial turbines, cross flow turbines), indicate that the total availability of tidal power may be much higher than previously as- sumed, and that economic and environmental costs may be brought down to competitive levels.
Tidal power traditionally involves erecting a dam across the opening to a tidal basin. The dam includes a sluice that is opened to allow the tide to flow into the ba- sin; the sluice is then closed, and as the sea level drops, traditional hydropower technologies can be used to gen- erate electricity from the elevated water in the basin.

2 GENERATION OF TIDAL ENERGY

Tidal power is the only form of energy which derives directly from the relative motions of the Earth–Moon sys- tem, and to a lesser extent from the Earth–Sun system. Tidal forces produced by the Moon and Sun, in combina- tion with Earth’s rotation, are responsible for the genera- tion of the tides. Other sources of energy originate directly or indirectly from the Sun, including fossil fuels, con- ventional hydroelectric, wind, biofuels, wave power and solar. Nuclear energy makes use of Earth’s mineral depo- sits of fissile elements, while geothermal power uses the Earth’s internal heat which comes from a combination of residual heat from planetary accretion (about 20%) and heat produced through radioactive decay (80%).
Tidal energy is extracted from the relative motion of large bodies of water. Periodic changes of water levels, and associated tidal currents, are due to the gravitational attraction of the Sun and Moon. Magnitude of the tide at a location is the result of the changing positions of the Moon and Sun relative to the Earth, the effects of Earth rotation, and the local geography of the sea floor and coastlines.
Because the Earth’s tides are ultimately due to gravita- tional interaction with the Moon and Sun and the Earth’s rotation, tidal power is practically inexhaustible and clas- sified as a renewable energy resource.
A tidal generator uses this phenomenon to generate electricity. Greater tidal variation or tidal current veloci- ties can dramatically increase the potential for tidal elec- tricity generation.
The movement of the tides causes a continual loss of mechanical energy in the Earth–Moon system due to pumping of water through the natural restrictions around coastlines, and consequent viscous dissipation at the seabed and in turbulence. This loss of energy has caused the rotation of the Earth to slow in the 4.5 billion years since formation. During the last 620 million years the pe- riod of rotation has increased from 21.9 hours to the 24 hours we see now; in this period the Earth has lost 17% of its rotational energy. While tidal power may take addi- tional energy from the system, increasing the rate of slowdown, the effect would be noticeable over millions of years only, thus being negligible.

2.1 Generating methods

Tidal power can be classified into three generating me- thods: Tidal stream generator, Tidal barrage, Dynamic tidal power.

Click to read more about journal- http://www.ijser.org/onlineResearchPaperViewer.aspx?Tidal_Power_An_Effective_Method_of_Generating_Power.pdf

A Few Aspects of Power Quality Improvement Using Shunt Active Power Filter

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1 INTRODUCTION

A harmonic is a component of a periodic wave having a frequency that is an integral multiple of the fundamental power line frequency. Harmonics are the multiple of the fundamental frequency, and whereas total harmonic distortion is the contribution of all the harmonic frequency currents to the fundamental. Harmonics are the by-products of modern electronics. They occur frequently when there are large numbers of personal computers (single phase loads), uninterruptible power supplies (UPSs), variable frequency drives (AC and DC) or any electronic device using solid state power switching supplies [1] to convert incoming AC to DC. Non-linear loads create harmonics by drawing current in abrupt short pulses, rather
than in a smooth sinusoidal manner.

Fig: 1 Difference between Linear and Non-Linear Loads

The terms “linear” and “non-linear” define the relationship of current to the voltage waveform. A linear relationship exists between the voltage and current, which is typical of an across-the-line load. A non-linear load has a discontinuous current relationship that does not correspond to the applied voltage waveform. All variable frequency drives cause harmonics because of the nature of the frontend rectifier.

1.1 Need For Harmonic Compensation:

The implementation of Active Filters in this modern electronic age has become an increasingly essential element to the power network. With advancements in technology since the early eighties and significant trends of power electronic devices among consumers and industry, utilities are continually pressured in providing a quality and reliable supply. Power electronic devices [2] such as computers, printers, faxes, fluorescent lighting and most other office equipment all create harmonics. These types of devices are commonly classified collectively as ‘nonlinear loads’. Nonlinear loads create harmonics by drawing current in abrupt short pulses rather than in a smooth sinusoidal manner. The major issues associated with the supply of harmonics to nonlinear loads are severe overheating and insulation damage. Increased operating temperatures of generators and transformers degrade the insulation material of its windings. If this heating were continued to the point at which the insulation fails, a flashover may occur should it be combined with leakage current from its conductors. This would permanently damage the device and result in loss of generation causing widespread blackouts.
One solution to this foreseeable problem is to install active filters for each nonlinear load in the power system network. Although presently very uneconomical, the installation of active filters proves indispensable for solving power quality [1][2] problems in distribution networks such as harmonic current compensation, reactive current compensation, voltage sag compensation, voltage flicker compensation and negative phase sequence current compensation. Ultimately, this would ensure a polluted free system with increased reliability and quality.
The objective of this project is to understand the modeling and analysis of a shunt active power filter.

Click to read more about journal- http://www.ijser.org/onlineResearchPaperViewer.aspx?A_Few_Aspects_of_Power_Quality_Improvement_Using_Shunt_Active_Power_Filter.pdf