Erdoğan AYDIN
Erdoğan AYDIN
In this study, a new code index modulation (CIM) aided spatial modulation (SM) technique based on the Euclidean distance and capacity optimized based antenna selection (EDAS/COAS), called EDAS/COAS-CIM-SM, is proposed for multiple-input multiple output (MIMO) systems. Since in the proposed EDAS/COAS-CIM-SM technique, incoming information data bits indicates modulated symbols, activated transmit antenna indices as well as their corresponding spreading code indices, data bits are conveyed not only by the modulated symbols but also by the indices of the active antenna and spreading code indices. Thus, the proposed two systems provide faster data rates while spending less transmission power and possessing better error performance than the conventional direct sequence- spread spectrum (DS-SS), SM, EDAS and COAS based SM (EDAS-SM, COAS-SM), and CIM based SS (CIM-SS) systems. In addition, in order to improve the overall performance of the CIM aided SM (CIM-SM) system, EDAS and COAS techniques are considered at the receiver. Computer simulations have also shown that the EDAS/COAS-CIM-SM system has better error performance than the CIM-SM system over the Rayleigh fading channels for binary phase shift keying (BPSK) modulation schemes.
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Nurhan Türker TOKAN
Nurhan Türker TOKAN
Emerging smart antenna systems require different beam patterns of multiple antennas. Although adjustable phase shifters are mostly used in continuousbeam systems, the Butler matrix is used in switching-beam systems due to its low cost and easy fabrication. In this study, an antenna-array-feeding circuit based on the Butler matrix that can be used for Multiple Input Multiple Output applications is designed for 5G new radio. With the proposed switching system, the control of four beams can be achieved. The Butler circuit, designed to cover the 3.5–4.2 GHz 5G band, has a low complexity and is capable of meeting the need for high data throughput. A simulation of the circuit and circuit sub-elements designed using a 0.508-mm-thick substrate material is performed using the Computer Simulation Technology Microwave Studio computer-aided design tool. Furthermore, a prototype of the Butler circuit is fabricated, and the amplitude and phase variations at the output ports are measured. An average transmission loss of the feed circuit is measured as 1.5 dB, and when the length of the Phase Shifter in the circuit is set to λ/8, with a four-element linear array added to the output of the Butler circuit, the main beam is steered to ±15o and ±35o having maximum gain in the 6.39–8.77 dBi range.
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A new floating gate MOS (FGMOS) universal current conveyor (UCCII) is proposed to have the properties of simplifier circuit topology, simpler signal processing and wider input swing. Since the FGMOS transistors are used in the proposed UCCII circuit, the number of transistors is reduced and the topology of the circuit is simplified because it is easier to get arithmetic operations in circuits by using FGMOS transistors when compared to conventional MOS transistors. At the same time, using FGMOS differential amplifier structure in the input stage of the FGMOS UCCII circuit increased the input signal swing resulting both an increase in the linearity of the circuit and an improvement in the voltage following properties. A single input multi output (SIMO) type universal filter application is given to show the versatility of the UCCII block. Both the proposed FGMOS UCCII circuit and filter circuit are simulated with SPICE program by using 0.35µm technology parameters. When the simulation results are analyzed it is seen that that the FGMOS UCCII circuit reached the expected improvements according to the MOS equivalent circuit and expected to be used in linearly tunable filters.
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Solgun SALİMİ, Amangaldi KOOCHAKİ
Solgun SALİMİ, Amangaldi KOOCHAKİ
The present study presents a new islanding detection method based on variational mode decomposition (VMD). In the method, the VMD transform of the voltage at point of common coupling is calculated, and then based on the decomposed modes, an islanding detection index for distinguishing between islanding and normal conditions will be derived. Pursuing this objective, the measured voltage is decomposed into four modes, and a new islanding detection index will be derived from their energy and their variations. Then, thresholds will be adjusted based on values of proposed index in various conditions on normal and islanding operations. The proposed algorithm decomposes the measured signal into a predetermined number of intrinsic modes around central frequencies; the method is insensitive to the noise and sampling frequency. To validate the method, a distribution network has been simulated in PSCAD/EMTDC, and the algorithm is tested on a variety of islanding and normal circumstances. The results illustrate desired performance of the proposed algorithm for conditions such as motor, nonlinear, and large load switching; as normal condition; and islanding condition with a variety of power mismatches between local load and distributed generation. The results demonstrate the desired performance of the method with respect to both speed and accuracy.
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Arithmetic Logic Unit (ALU) is the essential part of the Central Processing Unit (CPU) core which performs arithmetical operations such as addition, subtraction, division, multiplication etc., logical operations such as and, or, xor etc. and shift-rotate operations. The CPU performance is directly related to the performance of ALU. In this study, the 64-bit ALU has been designed by using the Very High Speed Integrated Circuits Hardware Description Language (VHDL) and Altera Field Programmable Gate Array (FPGA) families, synthesized and simulated with the help of Altera Quartus II (Intel, Santa Clara, CA, USA) v13.0sp1 and Modelsim-Altera v10.1d (Intel, Santa Clara, CA, USA) software. Many different studies are given about ALU Design and Implementation with the use of FPGA architecture and VHDL language. The difference of this study from recent studies is that the proposed design allows the processing of the signed numbers. Also, Conditional Sum Adder (COSA) is used in addition operation instead of Carry Ripple Adder (CRA) or Carry Look-ahead Adder (CLA) because of its benefit in fast addition and less propagation delay of Carry Chain.
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Set partitioning in hierarchical trees (SPIHT) is an efficient algorithm which is used for the image compression widely. SPIHT operates sequentially so, its
parallel implementation is difficult. In this study, the SPIHT algorithm is improved for providing that it is suitable for the parallel processing applications,
and the corresponding pipelined datapath is designed for the proposed enhanced SPIHT algorithm. The datapath is designed to have three stages as
preprocessing, list generation and output stream. In the preprocessing stage, the flags which are supports the list generation stage are constituted. List
of insignificant sets (LIS), list of insignificant pixels (LIP) and list of significant pixels (LSP) are formed in list generation stage. These lists contain the bit
values which generate the output bit stream. The performance of the improved datapath design has been tested by compressing different images, and
the obtained results are given.
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This paper presents an adaptive chaotic symbiotic organisms search algorithm (A-CSOS) for finding the solution of optimal reactive power dispatch
(ORPD) problem which is one of the main issues of power system planning and operations. The most important advantage of symbiotic organisms
search algorithm (SOS) is that is not need any particular algorithm parameters. However, the SOS algorithm has some features to be enhanced, like
falling into local minima and sluggish convergence. A-CSOS algorithm with adding new and improved features like adaptivity and chaos to conventional
SOS algorithm is proposed to solve ORPD problem. The ORPD problem is mainly focused on minimization of transmission loss (Ploss) and total voltage
deviation (TVD). To determine the optimal set points of control variables including generator bus voltages, tap positions of transformers, and reactive
power outputs of shunt VAR compensators is very crucial for minimization to Ploss and TVD. The proposed algorithm is implemented on IEEE 30-bus
test power systems for ascertaining the performance of A-CSOS algorithm on ORPD problem. The results showed that the proposed approach is up to
10.39% better than many of which the latest algorithms in literature and encourage the researchers to implement A-CSOS algorithm to ORPD problem.
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Prediction models provide the probability of an event. These models can be used to predict disease’s outcomes, reccurencies after treatments. This
paper presents an expert system called Symptom Based Clinical Decision Support Tool (SBCDST) for early diagnosis of erythemato-squamous diseases
incorporating decisions made by Bayesian classification algorithm. This tool enables family practitioners to differentiate four types of erythematosquamous
diseases using clinical parameters obtained from a patient. In SBCDST, Psoriasis, Seborrheic Dermatitis, Rosacea and Chronic dermatitis
diseases are described by means of well-classified set of attributes. Attributes are generated from the typical sign and symptoms of disorder. Based on
our clinical results, tool yields 72%, 93%, 89% and 95% correct decisions on the selected dermatology diseases respectively. System proposed will provide
the opportunity for early diagnosis for the patient and the expert medical doctor to take the necessary preventive measures to treat the disease; and
avoid malpractice which may cause irreversible health damages.
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This paper proposes a voice activity detection (VAD) method based on time and spectral domain features using multi-layer feed-forward neural network (MLF-NN) for various noisy conditions. In the proposed method, time features that were short-time energy and zero-crossing rate and spectral features that were entropy, centroid, roll-off, and flux of speech signals were extracted. Clean speech signals were used in training MLF-NN and the network was tested for noisy speech at various noisy conditions. The proposed VAD method was evaluated for six kinds of noises which are white, car, babble, airport, street, and train at four different signal-to-noise ratio (SNR) levels. The proposed method was tested on core TIMIT database and its performance was compared with SOHN, G.729B and Long-Term Spectral Flatness (LSFM) VAD methods in point of correct speech rate, false alarm rate, and overall accuracy rate. Extensive simulation results show that the proposed method gives the most successful average correct speech rate, false alarm rate, and overall accuracy rate in most low and high SNR level conditions for different noise environments.
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Mehmet Erkan YÜKSEL
Mehmet Erkan YÜKSEL
With the increasing popularity of embedded systems that consist of identifying, sensing, processing, and communication capabilities, the Internet of
Things (IoT) has enabled many new application scenarios in diverse scientific fields and provided an important opportunity to build efficient industrial
systems and applications. Most embedded systems consume power provided by fixed batteries with limited capacity. However, the main disadvantage of
batteries is that they must be periodically replaced with new ones or recharged when they are depleted. This kind of maintenance process increases the
cost and restricts the use in inaccessible places. Considering the limitations of battery power, alternative energy sources are required for interconnected
devices to operate efficiently and effectively. Harvesting or scavenging energy from the environment is an important strategy to design self-powered
systems employed in the IoT domain. Traditional energy harvesting applications use large energy storage devices to supply the power to the system
whenever needed. Batteryless energy harvesting techniques have advantages to operate long periods of time without maintenance. In this study, we
designed and implemented a supercapacitor-based, solar-powered wireless embedded system that can operate autonomously without the need of
maintenance and battery replacement. Our goal is to explore and analyze the applicability and usefulness of batteryless wireless data communication
and self-powered smart devices using energy harvesting technique in the IoT environment. In our experiments, we observed that our prototype boards
operate well with low-power consumption without any performance degradation.
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