Multi-Time Scale Optimal Dispatch for AC/DC Distribution Networks Based on a Markov Chain Dynamic Scenario Method and MPCRead the full article
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FIR to FIR Model Reduction with Linear Group Delay in Passband by SDP Optimization
Filter model reduction is an important optimization method in digital signal processing. A method of FIR to FIR model reduction using SDP optimization is proposed in this paper. At first, we use SDP to design an original FIR filter. Then we name a general K-order FIR digital filter with coefficient values equal to the first K + 1 filter coefficient values of . Finally, we design a new general K-order FIR digital filter connected in parallel with using SDP optimization. The experiment results show this method has good performance on the magnitude error and the linear phase in passband. Therefore, this method can be used in the field of digital signal processing.
A New Local Descriptor Based on Strings for Face Recognition
This paper proposes the use of strings as a new local descriptor for face recognition. The face image is first divided into nonoverlapping subregions from which the strings (words) are extracted using the principle of chain code algorithm and assigned into the nearest words in a dictionary of visual words (DoVW) with the Levenshtein distance (LD) by applying the bag of visual words (BoVW) paradigm. As a result, each region is represented by a histogram of dictionary words. The histograms are then assembled as a face descriptor. Our methodology depends on the path pursued from a starting pixel and do not require a model as the other approaches from the literature. Therefore, the information of the local and global properties of an object is obtained. The recognition is performed by using the nearest neighbor classifier with the Hellinger distance (HD) as a comparison between feature vectors. The experimental results on the ORL and Yale databases demonstrate the efficiency of the proposed approach in terms of preserving information and recognition rate compared to the existing face recognition methods.
Implementation of Optimal Protection Coordination for Microgrids with Distributed Generations Using Quaternary Protection Scheme
The flexible operation of microgrids, along with the availability of distributed generation (DG) units, causes a variety of changes in short-circuit current levels, magnitudes, and directions, which has undesirable effects on the operation of protection systems. Conventional protection schemes use typical directional overcurrent relays (DOCRs) with limited operating capability, unable to respond to microgrid operations in the manner of short-circuit current changes. In this paper, a quaternary protection scheme implemented with dual-directional overcurrent relays (dual-DOCR) and a protection control strategy is developed for protecting against faults in microgrids, taking into account the existence of DGs and connection and disconnection of DG units. The optimal dual-DOCRs setting and coordination are formulated as an optimization problem solved by evolutionary programming to minimize the relay operating times. The proposed protection scheme is implemented with a centralized protection control system based on the smart grid concept to increase the adaptability of the dual-DOCRs, which have multiple relay setting groups in accordance with system state changes. The simulation case studies are performed using the IEEE 14-bus test system, which is modified as a meshed microgrid operation. Test scenarios, including possible operations of microgrids, DGs availabilities, and different fault events, are analyzed and discussed. The comparative studies and simulation results show that the proposed scheme provides efficient coordination between the primary and backup relays and increases the responsibility of the protection system, which can be observed from the significant reduction in the relay operating times, resulting in the enhancement of selectivity, sensitivity, and speed of microgrid protection systems.
Latency-Aware Power Management in Software-Defined Radios
Cloud computing provides benefits in terms of equipment consolidation and power savings from higher utilization for virtualizable software. Cellular communication software faces challenges in cloud computing platforms. BSs create a specific load profile that differs from traditional cloud service loads. Cellular communication system implementations have real-time deadlines with fixed, periodic latency requirements. In this paper, we assess the suitability of an unmodified Ubuntu Linux OS running on a commodity server to operate latency-critical software using a 4G LTE BS software-defined radio implementation. Scaling of the CPU clock frequency is shown to be feasible without excessive impact on the platform’s ability to meet the 4 ms processing delay requirement imposed by the LTE standard. Measurements show the relationship between the processor’s operating frequency and the number of missed subframe processing deadlines to be nonlinear. The results obtained also indicate that a high computational capacity does not suffice to ensure satisfactory operation since fronthaul processing overhead can limit achievable performance. Use of offload-capable network interface cards is studied as a potential remedy.
Modeling, Analysis, and Implementation of Series-Series Compensated Inductive Coupled Power Transfer (ICPT) System for an Electric Vehicle
This paper focuses on the modeling and implementation of an Electric Vehicle (EV) wireless charging system based on inductively coupled power transfer (ICPT) technique where electrical energy can be wirelessly transferred from source to vehicle battery. In fact, the wireless power transfer (WPT) system can solve the fundamental problems of the electric vehicle, which are the short battery life of the EV due to limited battery storage and the user safety by handling high voltage cables. In addition, this paper gives an equivalent electrical circuit of the DC-DC converter for WPT and comprises some basic components, which include the H-bridge inverter, inductive coupling transformer, filter, and rectifier. The input impedance of ICPT with series-series compensation circuit, their phases, and the power factor are calculated and plotted by using Matlab scripts programming for different air gap values between the transmitter coil and receiver coil. The simulation results indicate that it is important to operate the system in the resonance state to transfer the maximum real power from the source to the load. A mathematical expression of optimal equivalent load resistance, corresponding to a maximal transmission efficiency of a wireless charging system, was demonstrated in detail. Finally, a prototype of a wireless charging system has been constructed for using two rectangular coils. The resonant frequency of the designed system with a 500 × 200 mm transmitter coil and a 200 × 100 mm receiver coil is 10 kHz. By carefully adjusting the circuit parameters, the implementation prototype have been successfully transferred a 100 W load power through 10 cm air gap between the coils.
Research and Software Design of an Φ-OTDR-Based Optical Fiber Vibration Recognition Algorithm
Distributed optical fiber vibration signal plays a significant role in the communication and safety of any perimeter security monitoring system. It uses light as an information carrier and optical fiber as a means of signal transmission and communication. Phase-sensitive optical time-domain reflectometry (Φ-OTDR) is used to detect the signals generated during events (intrusions or nonintrusion). This paper proposes the time-frequency characteristic (TFC) method for the recognition of the fiber vibration signal and designs and implements the corresponding software function module. The combination of time-domain features and time-frequency-domain features is called TFC; and it is based on the Hilbert transform and on the empirical mode decomposition (EMD) of time-frequency entropy and center-of-gravity frequency that is described. A feature vector is formed, and multiple types of probabilistic neural networks (PNNs) are performed on it to determine whether intrusion events occur. The experimental simulation results show that the monitoring system software can intelligently display the data collected in real time, which demonstrates that the proposed method is effective and reliable in identifying and classifying accurately the types of events. The data processing time is less than 2 s, and the accuracy of the system identification can reach 99%, which ensures the system’s validity.