This paper investigates the application of Adaptive Differential Evolution (DE) algorithm to enhance the performance of broadband antenna. A linear array consisting of half wavelength long unequally spaced parallel dipoles is designed to meet the increasing demand of extremely large bandwidth in wireless communication systems. Array is devised to maintain an almost invariable radiation patterns over a wide range of frequencies. Constant beam widths, good side lobe characteristics and minimum bearable voltage standing wave ratio (VSWR) are achieved for the allocated frequency band. Coupling effect has been taken into account via induced EMF method and minimized in terms of VSWR. In the proposed technique excitation and position of the individual array element are optimized in order to obtain a fixed SLL and minimum bearable VSWR over the proposed bandwidth. Dynamic range ratio (DRR) of excitation distribution is fixed at an optimum value for further mitigation of coupling effect. Phase distribution for all the elements is kept at zero degree. An adaption schemes to tune the scaling factor and crossover rate of population in DE is used to solve the design problem. Numerical results show the aforementioned modifications make the algorithm more effective to design the proposed broadband array.
This paper detects Indian coins of different denomination. The spiraling business transaction at vending machines and automated systems working on token have spurred better coin recognition techniques saddled with increased robustness.These techniques facilitate transaction making it easier in all forms of trade. Keeping all the essential factors in mind a system has been created which recognizes coin based on image subtraction technique. The process performs 3 checks(radius, coarse and fine)on the input image. The stated subsequent checks enable the technique to endorse Rotation Invariance, thus obviating the need of placing the coin at a certain angle. Also, the technique does away with the requirement of placing the front face of the coin up. Subtraction between the input object image and database image is performed. Further, plotting the resultant values gives minima which if less than a standard threshold establishes the recognition of the coin. Results of MATLAB based simulations have been reported.
With the emerging concept of Cognitive Radio and opportunistic spectrum access, spectrum sensing have gained new aspects since it is the main task on which the entire operation of cognitive radio rests. It is identified as the key requirement and is one of the most challenging issues in cognitive radio system. In this paper, a hybrid model for transmitter based spectrum sensing have been presented, in which various aspects of spectrum sensing problem under transmitter based detection are studied with a cognitive radio perspective. In this hybrid terminology, proper channelization of the three techniques (matched filter detection, energy detection and cyclostationary feature detection) have been performed with relevant discussion. The presented approach helps in detecting the idle spectrum bands (spectrum holes that is the underutilized sub bands of the radio spectrum) opportunistically with better utilization of the spectrum under non cooperative sensing with increase in the overall spectrum efficiency.
In this paper a two stepped septum polarizer is presented with matched feed using three pin to improve the gain and band width while polarization loss. This configuration shows about 10-15% bandwidth and it is therefore suitable for high sensitive, large bandwidth applications.
The Randomly deployed wireless sensor nodes form an unpredictable structure. Normally wireless sensor networks are distinguished from conventional networks by their energy constraints and limited computational power. Huge volumes of data are sensed and generated by the sensor nodes when they are deployed in the dynamic environment. Mostly the source and sink nodes are not within each other's transmission range. Congestion occurs when the intermediate nodes forward the data from source to sink. Many of the existing approaches focus on controlling the link level congestions in the network. Our proposed Queue reloading scheme controls the node level congestion. In order to avoid the retransmission of packets, the proposed scheme uses an alternative queue for caching the overflowed packets. The dropped packets are reloaded from the alternative queue when the current queue becomes available. The lifetime of the nodes depend on allocation rate. Our scheme saves the network resources; consuming less energy and aids achievement of improved efficiency and throughput. The node level congestion control is basically needed for WSNs, because the node can be deployed anywhere in the environment.
Energy consumption is an issue in general in information and communication technologies (ICT), but also cellular communications in particular. Base station sites are the main energy consumers in a mobile network. Their energy consumption significantly contributes to green house gas (Co2) emissions. It has been found that digital baseband is the main contributor to dynamic part of the power consumption in new base station deployments due to its explosive computational complexity. Hence, the implementations of baseband subsystem need to be energy efficient in advanced systems and thus to reduce Co2 foot print and save on energy costs. In this paper, we have presented an approach for evaluating energy efficiency metrics for any signal processing algorithm on TI's DSP and Xilinx FPGA. This evaluation of energy metrics is very much required to characterize the implementations and for quantifying the gains achieved from any energy efficient strategy. In addition, we showed that reducing execution cycles taken by signal processing algorithm effectively reduces its dynamic power consumption. As an example, FFT/IFFT algorithm, one of the critical block in OFDMA systems is considered for energy analysis.
Cryptography is one of the major concerned areas of computer and data security and a very promising direction in cryptography research is known as DNA Cryptography. DNA computational logic can be used in cryptography for encrypting, storing and transmitting the information, as well as for computation. Although in its primitive stage, DNA cryptography is shown to be very effective. In this paper, a proposal is given where the concept of DNA is being used in the encryption and decryption process. The theoretical analysis and implementations shows this method to be efficient in computation, storage and transmission; and it is very powerful against certain attacks. This paper also proposes a unique cipher text generation procedure as well as a new key generation procedure. Finally, to demonstrate the performance of the proposed method, its implementation is explained and the results are analyzed.
In this paper, we propose a simple technique for the reduction of high Peak to Average Power Ratio (PAPR), based on Clipping and Differential Scaling, in Orthogonal Frequency Division Multiplexing (OFDM) systems. In this technique, the amplitude of complex OFDM signal is clipped and then scaled in such a way so that the PAPR is reduced without causing much degradation in bit error rate (BER). We have determined the threshold values for clipping and scaling using Monte Carlo Simulations. We have presented PAPR and BER of the system considered using simulations for QPSK constellation. We have also compared the performance of the proposed PAPR reduction technique with the performance of the existing techniques.
Nonorthogonal Frequency Division Multiplexing (NOFDM) is a digital modulation technique that promises to provide extremely high spectral efficiencies. However, this modulation scheme is seldom used in practice due to the high computational complexity involved in decoding the received signal in the presence of noise. The basic aim of this paper is to reduce this decoding complexity. Here, we propose a low complexity detection algorithm which makes use of maximum likelihood (ML) decoding not over the entire signal constellation but over a proper subset of the constellation that lies on a hypersphere thereby reducing the computational complexity for decoding. Computational complexity has been evaluated for various values of transmitted power and the result has been plotted for both ML detection algorithm and the proposed algorithm at a fixed data rate. The BER performance for both the algorithms has also been compared at a fixed data rate and the result has been plotted. The results show that the proposed algorithm is far superior to ML detection algorithm in terms of computational complexity.
Optical burst switching (OBS) is a promising switching technology for realization of terabit optical network. However, the lack of optical processing capability results in increased blocking probability and limits the network performance. Efficient contention resolution is therefore necessary. Optical burst-switched networks are usually implemented using efficient contention resolution protocols like deflection routing, however deflection routing approach resolves the congestion by exploiting alternate available paths and utilizes the resources effectively. If contention is resolved by traditional deflection routing then there is no guarantee that the control packet will be able to reserve all the wavelengths successfully up to the destination on the alternate path, especially in a high traffic load situation. The present paper proposes a scheme of deflection routing by assigning suitable wavelengths to various routed paths based on respective traffic to be routed. A mathematical model for the same has been developed and the network performance has been simulated using MATLAB to establish congestion performance of the proposed scheme.
Subthreshold logic is an efficient technique to achieve ultralow energy per operation for low-to-medium throughput applications. To improve switching performance, energy/switching, and also the robustness of the subthreshold logic for the implementation of 1-bit static full adder, we propose the use of sub-FinFET (sub-threshold voltage FinFET) transistors. The power, speed and energy evaluation has been carried out using extensive simulation on HSPICE circuit simulator. The simulation results are based on 32 nm CMOS Berkeley Predictive Technology Model (BPTM).
In this paper a comparative study of Linear Prediction Coefficient (LPC) and Mel Frequency Cepstral Coefficient (MFCC) features is presented for text dependent speaker identification in clean and noisy environments. Noisy database was prepared by adding speech and F16 noises to clean database at -5dB, 0dB and 10dB SNR levels. The speaker identification performance with MFCC and LPC features for clean database is 96.65% and 93.65% respectively. MFCC features have also shown better identification rate in presence of both noises at all SNR levels as compared to LPC features. Gaussian mixture model (GMM) was used for training and testing purpose.
The mathematical model provides an insight into the complete behavior of the physical system that reduces the problem to its essential characteristics. The floating admittance matrix (FAM) approach is a neat method of mathematical modeling of electronic devices and its uses in circuits. The zero sum property of the floating admittance matrix provides a check to proceed further or reobserve the first equation itself. Voltage gain, Input & Output resistances are represented as cofactors of the FAM of the circuit. MATLAB plots have been analysed for the functions which lead to an interesting method for improving the Q- factor for the lossy networks which has been proposed in this paper.
Abstract: Log periodic array has been designed using inset fed rectangular microstrip patches for one, three and five elements. The antenna elements and feeding networks have been designed through Matlab programs. The simulation, fabrication and testing of the arrays have been carried out. The results are compared showing better frequency independent behavior by the five element array which is also proved by the experimental results.
In this paper, we have investigated a circuit model of the on-wafer interconnects for high-speed CMOS integrated circuits (ICs). Along with increasing the operating frequency, there are various factors like chip size, circuit density, complexity, cost and delay which make interconnects an important issue that has to be considered while designing ICs. At GHz frequencies, long interconnect wires exhibit transmission line behaviour and also traditional lumped and distributed RC models of interconnects are no longer accurate and result in substantial errors in predicting delay and crosstalk. Therefore, a RLC circuit model of interconnects is consider in this work, which takes into account the effects inductance also. Two coupled interconnects are used to show the effects of both capacitive and inductive coupling. The coupled circuit model is studied in terms of S-parameters namely, S11 and S21, which gives return loss and insertion loss, respectively. The proposed circuit model is simulated by using the Advanced Design System 2005A (ADS) by Agilent Technologies. These parameters are obtained for different cases considering both types of coupling collectively and individually.
Low power device design is now a vital field of research due to increase in demand of portable devices. This research paper proposes the modified Single Edge Triggered (SET) D-flip flop design for the portable applications. Design is tested for various substrate bias voltages in sub-threshold region to opt for better design. Design comparison between previously reported design and modified design is performed at 65nm and 45nm to show technology independence. Comparative simulation results show that area and power efficient SET D-FF design is better choice for portable applications.
On-chip inductive effects are becoming predominant in deep submicron interconnects due to increasing clock speed, circuit complexity and an increase in interconnect length. In this paper, a novel closed form delay metric has been proposed for the on-chip VLSI RLC interconnect. The model has also been extended for the case when the time of flight of the input signal is comparable. It is started with a distributed RLC line model of the interconnect and analytically solved the resulting diffusion equation for the voltage response and 50% delay has been calculated and has been compared with SPICE delay and error is within 7%. The proposed method also calculates 50% delay by taking the time of flight into consideration and result is compared with SPICE and the average error has been found to be within 6%.
Node capture attack is considered to be one of the most serious attack in WSN. An adversary physically captures a node so that she can steal all the confidential information stored in it and can launch further attacks by deploying clones of a captured node. To achieve this she needs to gather useful information regarding the network before capturing a node. Hence, a node capture by an adversary depends on how quickly she is able to gather the information regarding the network and about the target node. In this paper we have proposed a model for the process of gathering information by an adversary. We have also found the expected amount of information an adversary have at an arbitrary time t. Using the above information we proposed the expected time of a node capture based on the strength of an adversary and the dynamicity of the network.
Acute lymphoblastic leukemia (ALL) are a group of hematological neoplasia of childhood which is characterized by a large number of lymphoid blasts in the blood stream. ALL makes around 80% of childhood leukemia and it mostly occur in the age group of 3-7. The nonspecific nature of the signs and symptoms of ALL often leads to wrong diagnosis. Diagnostic confusion is also posed due to imitation of similar signs by other disorders. Careful microscopic examination of stained blood smear or bone marrow aspirate is the only way to effective diagnosis of leukemia. Techniques such as fluorescence in situ hybridization (FISH), immunophenotyping, cytogenetic analysis and cytochemistry are also employed for specific leukemia detection. The need for automation of leukemia detection arises since the above specific tests are time consuming and costly. Morphological analysis of blood slides are influenced by factors such as hematologists experience and tiredness, resulting in non standardized reports. A low cost and efficient solution is to use image analysis for quantitative examination of stained blood microscopic images for leukemia detection. A fuzzy based two stage color segmentation strategy is employed for segregating leukocytes or white blood cells (WBC) from other blood components. Discriminative features i.e. nucleus shape, texture are used for final detection of leukemia. In the present paper two novel shape features i.e., Hausdorff Dimension and contour signature is implemented for classifying a lymphocytic cell nucleus. Support Vector Machine (SVM) is employed for classification. A total of 108 blood smear images were considered for feature extraction and final performance evaluation is validated with the results of a hematologist.
Expanded graphite (EG) flakes are synthesized from natural graphite flakes of size ~2 μm employing chemical oxidation and thermal treatment method. The surface morphology and structural characterization of EG flakes are investigated using scanning electron microscope and X-ray diffraction respectively. EG flakes are mechanically mixed with novolac phenolic resin (NPR) in different weight ratios (30 wt%, 40 wt % & 50 wt %) and compressed with thermal treatment to develop expanded graphite/novolac phenolic resin(EG/NPR) composites. Shielding effectiveness (SE) of developed composites measured in the frequency range of 8 to 12 GHz shows a maximum values of -48 dB for 50 wt% EG/NPR composites.
