1. Shunt Active Power Filter for Power Quality Enhancement using Digital Notch Filter Control Strategy
Abstract—With the increasing number of applications, conventional equipment is proving insufficient for mitigation of power quality problems. This paper presents a Single Phase Shunt Active Power Filter (APF) designed to minimize power quality problems, which automatically adapts to changes in the network and load fluctuations in electrical systems by the use of digital notch filter control strategy. The power stage of the APF is based on two-leg full-bridge inverter, with a single capacitor in dc side, and a filter inductor in the ac side. It can be used for the compensation of harmonic components of current drawn by the non-linear load. Shunt active power filter operates as a current source injecting the current harmonics drawn by the load and letting the source to supply only the fundamental component.
IndexTerms—Active Power Filter, Power Quality, Harmonic Component, Non-linear Load, Two-Leg Full-Bridge Inverter, Digital Filter
2. Enhancing Power System Stability using VSM
(Virtual Synchronous Machine)
Abstract—The increasing integration of decentralized electrical sources like solar PV is attended by problems with power quality, safe grid operation and grid stability. The power from PV is injected to systems through inverter and this system does not have inertia like rotating mass of rotating generator. Hence, with increase in power injected from PV system, the transient stability of the system becomes poor.
The concept of the Virtual Synchronous Machine (VSM) describes an inverter which can establish virtual inertia and damping by using short term energy storage together with a power electronics inverter/converter and a proper control mechanism. The proposed system will then operate like a synchronous generator in exhibiting inertia and damping properties, while remaining inactive during steady state conditions. This paper presents the dynamic properties, damping and inertia, of the VSM and their contribution to the stabilization of the grid frequency and the attenuation of grid oscillations examined in a MATLAB simulation.
IndexTerms— Virtual Synchronous Machine (VSM), virtual inertia, virtual damping, frequency stabilization, inverter, Distributed Generator (DG).
3. Simulation and Control Design of Adjustable Speed Small Scale Hydro Generation for DG Applications
Abstract— Generally, a small scale hydro generation is a fixed speed run of river type plant that uses mechanical regulation for turbine inflow thus by controlling active power generation. Such mechanical control is a complex mechanism and is more affordable for larger systems. This paper proposes an advanced control design of small scale hydro generation based on a variable speed with smaller, lighter and more efficient variable speed turbine. The variable speed operation of such plant is aimed to increase efficiency in order to generate maximum power at various discharges of turbine inflow. The suggested design is comparatively simpler and eliminates all mechanical controls through an advanced electronic power conditioning system (PCS) for connection to the electric grid according to the grid’s requirements. In this way, it allows obtaining higher reliability and more efficiency of such small scale hydro power plant. A complete model of the hydropower plant with advanced control scheme is designed. The performance of the proposed scheme is validated through simulation in MATLAB/Simulink.
Index Terms— Distributed generation (DG), Small scale hydro generation, Power Conditioning System (PCS), Maximum power point tracking (MPPT), Hysteresis Band Current Control.
4. Sphere Detection Technique: An Optimum Detection Scheme for MIMO
Abstract — In this paper, various multiple input and multiple output (MIMO) detection techniques have been compared on the basis of BER performance and complexity. Maximum likelyhood (ML) detection method has shown optimal solution in MIMO systems compared to conventional detection techniques. However, higher receiver complexity leads to use of lower complexity techniques such as zero forcing (ZF) and minimum mean square error (MMSE) having relatively poor performance. Successive interference cancellation combined with ZF or MMSE has much improved performance but vulnerable to error propagation. Ordered succesive interference cancellation with MMSE (MMSE-OSIC) has reduced error propagation probability and gave the better performance. A new detection technique sphere detection (SD) based on Schnorr-Euchner enumeration has provided ML solution with much less computational complexity. For simulation, Rayleigh channel model has been considered.
Keywords - MIMO, ZF, MMSE, SIC, ML, Sphere Decoder
5. ENERGY BASED FREQUENCY DETECTION TECHNIQUE FOR COGNITIVE RADIO SPECTRUM SENSING
Abstract - Several studies have revealed that spectrum congestion is primarily due to the inefficient use of spectrum and unavailability. The bandwidth becomes expensive due to a shortage of frequencies. Therefore for efficient utilization of spectrum, we need to sniff the spectrum to determine whether it is being used by primary user or not. The term cognitive radio refers to the adoption of radio parameters using the sensed information of the spectrum. There are various spectrum sensing techniques proposed in the literature but still there is no any practically defined technique for spectrum sensing. There are three major categories of spectrum sensing techniques; transmitter detection, receiver detection and interference temperature detection. This work proposes an energy based detection technique for cognitive radio spectrum sensing, which senses the existing licensed primary users and then inserts the unlicensed secondary users to the unallocated frequency determined by the system. It continuously scans the frequency spectrum and shifts the secondary user to next unallocated band if primary user starts to transmit at that frequency. Cognitive based spectrum management technique increases the spectral efficiency.
Keywords: Cognitive Radio, Energy Detection, Primary User, Secondary User, Power Spectral Density
6. An Optimization Approach for Load Shedding Applying Genetic Algorithm
Abstract: Curtailment of electric load from the electrical network is required to recover the system when there is shortage of energy. The way of curtailing electric load may be different depending on the situation of the system. An optimal load shedding is to curtailed load from the system to minimize the effects among consumers. The optimal load shedding is a nonlinear programming and highly constrained optimization problem. The objective function of it is minimization of power loss and outage cost of different customers so as to obtain optimized value of new demands of all loads. In genetic algorithm approach for optimal load shedding, new load demands of all load buses are generated randomly within their specified load cut range in different combinations. GA approach based optimal power flow is highly satisfactory and is the highest optimized approach than classical approach which is tested in IEEE-14 bus power system network.
Key Words: Genetic Algorithm, Optimization, Optimal Power Flow, Load Shedding
7. Numerical Analysis of Sensor Deployment in Wireless Sensor Network
Abstract—Ad-hoc wireless network with a huge amount of static or mobile sensors is called wireless sensor network (WSN). The sensors collaborate to sense, collect and process the raw information of the phenomenon in sensing area (in-network), and transmit the processed information to the observers. Robust, fault tolerance, and furthermore are prime factors to be consider before designing wireless sensor network. It is theoretically proved through math modeling, theoretical analysis and formula deducting that sensor deployments in the form of equilateral triangle, as a rule, are better than those in the form of square, hexagon and octagon. The theoretical analysis formula has given that minimum number of sensor nodes is demanded in a given sensor field if the field is covered fully and seamlessly and efficient coverage area and efficient coverage area ratio decrease with increase of sensor nodes comparing to same grid.
8. An Introduction to Parallel Processing Using FPGAs
Abstract—This document introduces FPGAs (Field Programmable Gate Arrays) and highlights their parallel processing capability. FPGAs are reprogrammable hardware chips for implementation of digital logic. Their reconfigurability is attributable to the presence of configurable logic slices and interconnects.
The possibility of hardware configuration in FPGAs allows the designer to design multiple modules that run parallel and independently to each other. This paper discusses how FPGAs offer true hardware parallelism as opposed to microprocessors that execute a single instruction per cycle. The parallel processing of FPGAs allows them to perform much faster than microprocessors even with a much slower clock speed. Their parallel processing capability makes them popular in applications where large amount of data need to be processed and where algorithms used are based on parallel computing. This paper deliberates on some areas which benefit from FPGAs’ parallel processing such as DSP, Data Acquisition and Processing, Text Parsing and Image/Video Processing.
Index Terms—FPGA, Parallel Processing
9. Electrospinning: How to Produce Nanofibers Using Most Inexpensive Technique? An Insight into the Real Challenges of Electrospinning Such Nanofibers
Abstract: This paper highlights about the use of a very simple and inexpensive device for the production of nanofiber of diameter less than 100 nm. There are several literatures that explain the different methods for preparing as spun nanofibers but they are very time consuming and difficult in reproducing results unlike the robust electrospinning device discussed in this paper. Though easier to use, this methodology has still a lot of challenges that should be addressed in the upcoming researches. We have briefly summarized few challenges and application areas that require utmost attention to excel in the field of nanotechnology. Despite several application areas where the technique of electrospinning can be deployed in the fabrication of nanofibers, we have mainly emphasized energy related devices in the field of nanoelectronics.
Keywords: electrospinning, energy harvesting, filtration, nanofiber, nanoelectronics, nanoscale materials, solar cell
10. Characterization of CD-ROM memory
Abstract — The Compact Disc (CD) was originally developed in 1982 from the laser disc for high quality audio recording. The CD audio specification was extended in 1984 to CD-ROM (Read Only Memory) for computer application and was extended to Data CD, Photo CD, Video CD and DVD. There are uses a similar bit structure where bit indicate pits which represents whether the data bit is ‘0’ or ‘1’. It is tremendous interest to fix data or memory to CD-ROM. We characterized the CD-ROM using atomic force microscopic (AFM) operating in non contact mode (NCM). The number of pits of Video CD was found ( no. of pits =25) more than other two(Data CD and Audio CD) CD-ROM as shown in figure 1 ; Depth of pits of Audio CD (0.12µm)was found to be less than other two. We characterized width and length of pits for all three CD-ROM(Data CD, Audio CD and Video CD).
Key words: CD-ROM, AFM, memory management, pits, NCM-AFM
11. COMPARATIVE ANALYSIS OF TDMA SCHEDULING ALGORITHMS IN WIRELESS SENSOR NETWORKS
Abstract — Energy conservation is a major issue in Wireless Sensor Network (WSN). In order to obtain energy conservation, Time Division Multiple Access (TDMA) has been discussed as one of the potential solution. Many researchers proposed TDMA as a Media Access Control (MAC) in order to conserve energy. The main advantage to using TDMA MAC is avoidance of collision of data packets during transmission and the added facility to use sleep modes. The use of sleep mode enables switching off the radio antennas thus reducing the energy conservation. Prior to usage of TDMA MAC, scheduling of the sensor nodes, i.e. providing time slot to the sensor nodes must be performed. Efficient scheduling of transmitting time slot in a TDMA is important for low power WSN. In this work, two decentralized scheduling algorithms Distributed Randomized TDMA (DRAND) and Deterministic Distributed TDMA (DDTDMA) are compared. In these algorithms, flowing the messages among the sensor nodes the scheduling is performed by assigning transmitting time slot to each node. So, their efficiency is analyzed based on schedule length, message complexity and convergence time to obtain scheduling. It was found that DDTDMA is an efficient algorithm than DRAND in terms of schedule length, message complexity and convergence time.
Keywords — Wireless Sensor Network, Time Division Multiple Access, Distributed Randomized TDMA, Deterministic Distributed TDMA
12 Comparative Study of Space Time Block Codes and Space Time Trellis Code over Rayleigh Fading Channel
Abstract—Multiple-input multiple-output (MIMO) systems are today regarded as one of the most promising research areas of wireless communications. This is due to the fact that employing more than one transmit or receive antenna increases channel throughput, and different strategies have been developed in order to achieve diversity advantage. Space-time codes combine coding gain with diversity gain and preserve orthogonality between antennas. Space Time Block Code (STBC) provide diversity gain however Space Time Trellis Codes (STTC) provides both the coding gain and diversity gains. The concept of STTC has been introduced to provide improved error performance of MIMO channels. It has been shown that STTC can provide a full diversity order as well as additional signal-to-noise ratio (SNR) advantage, or coding gain compared to the STBC. In this paper we implement the performance analysis of STBC and STTC over Rayleigh fading channels. We present here the design of the 4-PSK with different number of antennas and at different (mainly 4, 8 16 and 32) states.
Index Terms— Space time block codes, Space-time trellis code, multiple transmit antenna, multiple receiver antenna, diversity, wireless communication, convolutional encoder, maximum likelihood, viterbi decoder
13. Content Based Image Retrieval System: An Overview and Various Approaches
Abstract— Content based image retrieval system (CBIR) retrieves images from large databases based on visual features such as colour, texture and shape In CBIR each image which is stored in the database has its features that are extracted and compared to the features of the query image. This article describe the fundamentals of CBIRS and various approaches use to design the systems.
Index Terms— Image retrieval, Content Based Image retrieval
14. Cloud Computing: Benefit for Educational Institutions and Students
Abstract-Education today is becoming completely associated with the Information Technology on the content delivery, communication and collaboration. The need for servers, storage and software are highly demanding in the universities, colleges and schools. Cloud Computing is an Internet based computing, whereby shared resources, software and information, are provided to computers and devices on-demand, like the electricity grid. Currently, IaaS (Infrastructure as a Service), PaaS (Platform as a Service) and SaaS (Software as a Service) are used as business model for Cloud Computinginfrastructure provided by Microsoft, Google and Amazon Web Service.This is a technology for many of the organizations with its dynamic scalability and usage of virtualized resources as a service through the Internet. It will likely have a significant impact on the educational environment in the future. It is an excellent alternative for educational institutions which are especially under budget shortage in order to operate their information systems effectively without spending any more capital for the computers and network devices. Universities can take advantage of available cloud-based applications offered by service providers and enable their own users to perform business and academic tasks in the universities where the use of computers are more intensive and what can be done to increase the benefits of common applications for students and teachers. In this paper we will review the features the educational institutions can use from the cloud computing providers to increase the benefits of students and teachers.
Keywords: IaaS, PaaS, SaaS, Amazon, Microsoft Live@edu, Google Apps.