Abstracts:Traditionally, the data rate of a digital signal processing system is bound by the processing speed. In this article, a formal approach for overcoming this limitation and allowing high-data-rate applications to run on relatively slow processors is presented. This approach allows the time sampling period to be much shorter than the time required to process an input sample; in effect, an ultrahigh-speed system is obtained where the sample rate exceeds the processing rate by a factor controlled by the system designer. The proposed approach is applied to the multirate decimation algorithm and its associated dependence graph. A directed acyclic graph (DAG) is then obtained from it using a scheduling policy. The DAG is then partitioned using an interlaced partitioning scheme. Multiphase/multirate clocking is used to synchronize the different components of the system. The number of partitions required depends on the I/O rate and processor speed. The proposed approach speeds up the system at the expense of extra latency and hardware resources.

Abstracts:We present a novel scheme to formulate the throughput and the average number of successfully transmitted packets in a multinode Bluetooth low-energy (BLE) platform during each connection event. In this scheme, the wireless link is considered to be error prone which leads to the existence of uncorrelated bit error. Our proposed scheme considers factors that cause a connection event to close. The effect of master’s scheduling algorithm and BLE parameters on this scheme are also discussed to establish a comprehensive study on finding the throughput of a peripheral node in a BLE network. It is clear that an analytical model to formulate the throughput of a node offers a beneficial guideline for understanding the BLE throughput and ultimately the types of applications for which BLE technology would be a suitable option. We performed extensive experiments on the BLE v4.2 platform to investigate the throughput of a BLE node in a multipacket data transmission during a connection event. The results of our experimental study show some of the deficiencies that exist in the existing BLE devices such as the limitation on the maximum allowable packets during a connection event or the design of the scheduling process used by the central node.

Abstracts:Based on the optimized coprime array (OpCA), we propose a real-valued Toeplitz matrix method. This article analyzes the feasibility of converting the manifold matrix of a virtual domain constructed from a physical array into a real-valued matrix, and the unitary estimation of signal parameters via rotational invariance technique is introduced to transform the equivalent received signal rearranged Toeplitz matrix into a real-valued matrix and obtain directions of arrival (DOAs). Moreover, the proposed method offers higher estimation accuracy. Simulations are demonstrated to prove the validity of this method.

Abstracts:Many noncoherent distributed strategies for cooperative sensor networks that do not require channel knowledge at any antenna to overcome the overhead involved in channel estimation are lately suggested; however, these strategies suffer from low system performance in terms of bit error rate (BER) and a comparably high decoding complexity. Differential beamforming strategies have recently been proposed to overcome these problems; however, they are implemented using the four-phase protocol. Thus, we propose a new strategy based on the three-phase protocol to increase the symbol rate. By doing this, a significant improvement can be achieved in the overall system performance. Hence, in this article, a new bidirectional differential beamforming strategy is suggested: 1) to be applied on the three-phase protocol instead of the four-phase protocol; 2) to be applicable for a decentralized wireless sensor network using single-antenna sensors distributed randomly between the communicating base stations; 3) to enjoy low decoding complexity; and 4) to improve the network performance in terms of BER by maximizing the received signal-to-noise ratio at the receiving base station without requiring channel knowledge at any antenna in the whole network. From our simulation results, the proposed strategy shows a substantially improved BER performance compared with the current state-of-the-art ones.

Abstracts:This article presents two new approaches of fetal electrocardiogram (ECG) signal (FECG) separation using the input-mode adaptive filter (IMAF) and the output-mode adaptive filter (OMAF). Both approaches use the recursive least-squares (RLS) and the least-mean-squares (LMS) algorithms and a single-reference-generation block. In the IMAF, the filter’s primary input is connected directly to the abdominal signal. The reference signal is generated by windowing the abdominal signal according to the locations of the QRS MECG pulses. In the OMAF, the filter’s primary input is connected to the output stage of a blind source separation block. The reference signal is generated by windowing the raw FECG signal, from the BSS output, according to the locations of the QRS pulses of the extracted MECG signal. We selected the null space idempotent transformation matrix (NSITM) as the BSS algorithm used in this work. Results from real Daisy and Physionet databases show the successful extraction of the FECG signal. Results from synthesized data from Physionet databases, using OMAF, show considerable improvement in extraction performances over NSITM and IMAF when the fetal-to-maternal signal-to-noise ratio (fmSNR) increases from −30 to 0 dB. This study demonstrated that the OMAF is a feasible algorithm for FECG extraction.

Abstracts:This article introduces a concept to extend the base speed of a switched reluctance motor (SRM) from the perspective of the motor’s design. Conventionally, designs prioritize a high saliency of SRM in order to produce more torque with the same current. However, the speed range is limited in the conventional design. The back EMF is the key factor that restricts the speed of the SRM from further increasing due to its strong reaction to the phase terminal voltage applied, which is especially severe at high-speed operation. Therefore, in this article, the design of an SRM with a lower inductance slope is proposed. The reduction of the motor’s saliency in the proposed idea can effectively diminish the back EMF; thus an extended base speed and wider constant torque range can be achieved. Comparative simulation results from the conventionally designed motor and the motor designed by the proposed idea are given, which demonstrate that the base speed is enhanced and the current control can be maintained at a higher speed in the proposed idea.

Abstracts:In order to improve transient response and robust tracking performance, an adaptive nonsingular terminal sliding mode control (ANTSMC) strategy is developed for bidirectional dc–dc converter (BDC) of hybrid energy storage systems (HESSs). By using the adaptive rules, the estimated values of load variations, external input voltage, input current, and output voltage can be obtained. Then, the voltage tracking error can be calculated based on the estimated value and the actual value. The fast terminal SMC strategy is proposed such that the tracking error converges in a finite time. Simulation results, compared with conventional PID, second-order sliding mode, show that output voltage can robustly track the reference voltage with fast response.

Abstracts:This article develops a novel average torque control (ATC) scheme for switched reluctance (SR) motor on the basis of a brand-new microstep flux–current locus controller. The proposed ATC is based on the calculation of the average torque from the converted mechanical energy that can be illustrated as an enclosed area in a flux–current plane. It has the superior advantage that it is able to control the average torque over any arbitrary small-angle intervals, whereas the conventional ATC can control only the average torque for a whole stroke. In order to realize the proposed ATC, a flux–current locus controller, which consists of a hybrid flux controller and current controller as well as involve the microstep process, is introduced in this article. The flux–current locus of the energy conversion loop is controlled for the first time in the literature. With the locus controller, it is possible to achieve a better energy conversion ratio and the ATC. In order to verify both the proposed locus control method and the ATC for SR motor, detailed simulation results and discussion are provided.

Abstracts:This article is concerned with the asymmetrical control strategies of a four-channel dc/dc buck converter in the continuous current conduction mode (CCM). The converter has two input and four output channels. Energy equations of the converter are studied, and asymmetry of input voltages, output voltages, and loads are examined in the CCM. The proposed control strategy allows us to directly control the power flow in each channel without any unwanted consequences for the rest of the channels among these conditions. The main advantage is the direct control of the total transferred power by the positive sequence of the capacitor voltage, the power exchange among the input channels by the negative sequence of the capacitor voltage, and the power exchange among the output channels by the inductor currents. Calculating these currents also helps to determine whether the converter at a certain point operates in the CCM or in the boundary mode (where zero current switching is possible). Feasibility of zero-voltage switching is simplified by this method. Converter efficiency is showed to be 83% at asymmetrical output voltages in the CCM. Theoretical studies are confirmed by both numerical simulations and laboratory experiments on a 100-W prototype. The studied converter can be applied in supplying multilevel inverters.

Abstracts:We present a parametric framework (UFleSe) with a user-friendly interface having a search engine that enables regular users (without the need of neither technical nor theoretical knowledge) to define their fuzzy concepts, rules, similarity relations, synonyms, antonyms, and personalizing their definitions for different users, and to link them with the crisp database fields for performing flexible, expressive queries in a language close to natural language. It works over multiple modern and conventional data formats, such as JSON, SQL, Prolog, CSV, XLS, and XLSX. We present the syntax involved in the construction of our various flexible searching criteria and their personalizations. Furthermore, we present the architecture of this novel system that combines fuzzy, crisp data, and similarity relations in its queries to return constructive answers ordered by a degree of searching criteria satisfaction (truth-value between 0 and 1). Finally, we include a comparative analysis of different fuzzy querying systems here, and we provide various experiments, to show the system behavior, performance, efficiency, and scalability as well.