Recent Advances in Electrical & Electronic Engineering - Volume 11, Issue 4, 2018

Background: Design of an ultra-low voltage 0.28V CMOS VCO based on current reused topology for low power application is presented. The high performance of ultra-low voltage operation is achieved by way of the transformer feedback and body bias technique. Methods: The total power dissipation can be achieved as low as 260μW, while VDD1 and VDD2 are both 0.28V. The swing of output signal above the VDD supply voltage is improved by transformer feedback loop. The tuning range of proposed VCO is from 2 to 2.3 GHz under 0.28V supply voltage which PMOS and NMOS transistor with the threshold voltage is around 0.52V and -0.52V, respectively. Result: The measurement of phase noise is -106.5dBc/Hz at 1MHz offset from the 2.26GHz frequency carrier at 0.28V. Conclusion: The chip is implemented with 0.18μm CMOS process and its figure of merit is - 179.4dBc/Hz.

Objectives: The experimental platform of China Space Station has been designed. It can be used to study dynamics and attitude control of China Space Station. Dynamics model of China Space Station is made based on China's future space station system. Methods: Besides, simulation model of China Space Station is build, and its dynamics and attitude control is simulated. Conclusion: Finally, the experimental system is used to realize space station dynamics and attitude control, the system has good performance on structure vibration-attitude coordinated control of spacecraft, which is based on Dspace platform.

Background: This paper presents a novel Ultra-Wideband (UWB) balanced sub-nanosecond monocycle pulse generator sing Step Recovery Diodes (SRD) for an inter/intra-chip wireless interconnect communication system. Methods: The new UWB monocycle pulse generator has been simulated using Advanced Design System (ADS). This pulse generator employs wideband microwave bipolar transistor, transmission line, Schottky diodes and compact charging and discharging circuitry. Simple transient analysis and design of the circuit are presented along with their operating principles. The pulse generator produces truly balanced monocycle pulse having 200-ps pulsewidth, 2V peak voltage and 10-MHz repetition rate. Results: The generated monocycle pulses also have very symmetrical positive and negative portions and low ringing level. Conclusion: It can be used as both transmitter feeding UWB balanced antennas without broadband balun and UWB receiver balanced pulse generator that switches the sampling gate which commonly consists of two or four Schottky diode.

Background: A wide-band wide-beam Dielectric Resonator Antenna (DRA) is proposed in this paper. Methods: A cylindrical dielectric resonator operating in TM01δ mode is placed on a hybrid-structure ground which consists of a corner-reflector and a pentagon plate with edge-fold. With this structure, wide-band wide-beam characteristics can be achieved. Results: From simulation results, the impedance bandwidth (|S11|< -10 dB) of the antenna is from 1.8 to 3.14 GHz. The radiation pattern is stable, and the 3dB beam-width of H-plane is larger than 160° over the impedance bandwidth. Conclusion: A prototype of the proposed antenna is fabricated and tested, and the testing results are in agreement with the simulation.

Background: Antenna can serve as transmitter or receiver of electromagnetic energy (power). Circular path antenna as a single and as an array microstrip antenna will be used in this paper. Methods: Five array microstrip antennas with different amount of patch will be designed to get different amount of return loss variables, as well as discovering its effect on the power efficiency of the antenna. Results: By discovering the correlations between these two variables, we can make antenna more efficient in its usage. Designing and simulation of these antennas will use FR4 substrate and the frequency set in 2.4 GHz. Conclusion: The amount of the return loss has successive values, starting from -14.981175 dB, - 17.090297 dB, -19.620465 dB, -25.962626, to -34.316575 dB, while the successive value of Power Efficiency starting from 0.911294871 up to 0. 95411176. It is proved that the lower return loss, the higher power efficiency.

Background: The cooling effect of wind speed and wind direction was assessed using an 820concentrator photovoltaic module and wind tunnel. This study allowed us to define the best setting for concentrator photovoltaic module that allowed the highest cooling effect and temperature drop, which was the main goal of this research. Methods: Solar cell used in this module is triple-junction solar cell consists of InGaP/InGaAs/Ge layers. The setting inside the wind tunnel was set to meet the module temperature condition as in outdoor environment. The module tilt angle was set to 10°, 45° and 80°. The module azimuth was set to 0°, 45°, 90°, 135° and 180°. Altogether there were fifteen set up conditions. Also the wind speed was set to 2, 5 and 8 m/s respectively. Results: Cooling effect was most effective when the azimuth angle was set at 90°, which means that wind was blowing from the side of the module. Conclusion: All set up conditions demonstrated that the module cools down at higher wind speed. In addition, azimuth of 90° shows the highest average amount of temperature drop of the solar cells.

Introduction: In Very Large Scale Integration (VLSI), routing is the process of making connections among objects reasonable in the specific area and some cost metrics (i.e., routability) are optimized. It is a crucial step in VLSI physical design as the performance of a chip depends on the routing results heavily. Methods: In this paper, by congestion-based routing modeling, a multilevel based routing optimization method is developed to solve the VLSI routing problem. In the routing optimization method, the global and the detailed routing phases run alternately. At each level of the multilevel framework, global and detailed routing paths for each local net are identified. Moreover, some strategies are used to improve the routing results. Results: After detailed routing, a resource estimation is designed to obtain more accurate routing resources for the next level, and an ultimate congestion strategy is used to improve the pass rate of the nets. Experimental results on standard tested benchmarks demonstrate that the proposed method is effective and efficient to improve the routability of a chip.

Objective: Aiming at the difficulty of extracting weak faulty vibration features of generator in practical performing, a novel method named self-adapted multi-scale top-hat transformation (SAMST) is proposed to enhance the detection of the characteristic vibration signals. Methods: Different from other studies, this method employs the Sine-Structure Element (SSE) which is more similar to the signals appear in electrical systems to filter the noise. The most optimal scale of the SSE is obtained by using the method named Feature Amplitude Energy Radio (FAER) to enhance the characteristic faulty components. Experiment studies for an MJF-30-6 type fault simulating generator under the stator inter-turn short circuit fault confirm the advantages of this method. Results: It is shown that the proposed method can not only enhance all of the three characteristic frequency components of the stator vibration signal respectively at 2f, 4f, and 6f (f is the electrical frequency), but also depress the strong background noises and retain the detailed information at the same time. Conclusion: This method is probably to offer more convenience for the fault diagnosis of generator and therefore has practical application values.

Background: Madeira Wine can only be sold to the final consumer after a certain aging process that improves its properties. This process requires investment in the wine itself, the storage space and the temperature control and monitorization. The aging process takes a minimum of 3 years but can go up to more than 10 years. Methods: It has been shown that it can be speed up if the wine is kept under certain conditions with a slightly higher temperature. To control this process constant monitoring is required, namely for the temperature parameter inside the tanks to get a high quality wine. Up to now it is still mostly done in a manual way. To improve the process and reduce costs, a low cost automatic temperature control method has been developed and implement for Madeira Wine, using the tanks of a pilot scale tank. Conclusion: For this solution a simple Direct Inverse Control presented the best performance.

Objective: Effectiveness of data reduction directly influences the quality of reduced data, design of reduction process and selection of relevant algorithms or model, thus ultimately affecting flexibility and extension of the data reduction method and its implementation system. In view of the deficiencies of the data reduction effectiveness evaluation system including imperfection and weak applicability of index system, with lack of pertinence and neglecting the personalized needs of users, three evaluation indexes were put forward to comprehensively reflect the rate of data amount reduction, the rate of statistical difference and the rate of average information loss after data reduction. Methods: On the basis of this, an evaluation method of data reduction effectiveness based on users' interesting degrees was proposed. Results: Through this method, subspace of the weight of indexes described users' preference of index, and it was accessed according to historical data. Conclusion: The acceptable degree of reduction effectiveness is calculated approximately using the Monte Carlo simulation, which implements the method of effectiveness evaluation of data reduction geared towards different users and provides a quantitative basis for recommending data reduction method for system users focusing on different aspects.

Objective: In view of the issue that particle swarm optimization algorithm is easy to fall into local optimal solution and low convergence precision when searching for the feasible space solution of complex multimodal functions, the paper proposes an adaptive particle swarm optimization algorithm (PSO) based on aggregation degree. Methods: The algorithm firstly makes a random disturbance to search global optimal solution through differential evolution method according to the size of population aggregation to increase the diversity of particle swarm and improve its global searching ability. Then the adaptive adjustment is made to the inertia weight parameter of particles in accordance with the aggregation degree of particles. Conclusion: The simulation example of typical optimization problems suggests that this algorithm can improve the population diversity, particle activity, convergence performance and searching ability of PSO.

Background: In this paper, we theoretically analyze the topic of topology optimization theory and parallel data analysis model based on resource scheduling algorithm for cloud computing. Cloud computing is a virtual computing resource pool, which provides dynamic deployment and allocation of these resources to the user via the Internet. Methods: Cloud storage is to focus on providing internet-based online service. Users don't need to consider storage capacity, the types of storage devices and the data storage location as well as data availability. The challenge for the cloud system is a resource scheduling algorithm which will dramatically influence systematic performance. To deal with the mentioned challenges, our research proposes the following novel research. Results: (1) We analyze the basic topology optimization methodology to propose revised modification approach for cloud system which is fitter for the cloud environment. (2) To deal with the large-scale data, we propose the parallel data processing model to separate computation to the different sub-systems which will enhance the system robustness and capability. (3) We modify traditional resource scheduling algorithm with the prior theory which enhances the overall performance mainly to the orientation of matrix to carry on the design of the optimal solution for the various optimization standards. Conclusion: As is indicated in the experimental part, our methodology outperforms other state-of-theart algorithm.

Background: Aiming at the characteristics of PCB photoelectric image which have ambiguity and noise, a circle detection method of PCB photoelectric image based on improved Hough transform is proposed. Methods: Firstly, the basic principle of circle detection based on traditional Hough transform algorithm is discussed, and its disadvantages are pointed out. Secondly, the basic principle of circle detection method based on improved Hough transform is analyzed in detail, and it has some advantages such as smaller amount of data and faster speed. Results: Lastly, in order to prove the correctness of the basic principle analysis, a real experiment of PCB photoelectric image circle detection is actualized, both the subjective results and the objective results verify the superiority of the method. Conclusion: By using the method, the edge information obtained is the best and the computed time is the shortest in these methods mentioned in the experiment.

Background: In order to avoid undesired slide or damage, desired grasping force should be discrepant by the prosthetic hand when grasping soft or hard objects. Methods: A method was proposed in which a force sensor and an optical encoder are used to estimate the stiffness of the object being grasped. Based on contact-impact force model, a fuzzy logic system for stiffness estimation determined by contact force and the rotating angle of motor is constructed. Results: In order to avoid undesired deformation, the main controller modifies the PID gains based on the estimated stiffness of the grasped objects. Conclusion: The experiment results are presented to demonstrate the effectiveness of the proposed method.

Background: In order to meet the air-conditioning temperature control requirement and save energy, the mathematical model of the plant and the heater temperature control system is constructed according to the principle of energy conservation on the basis of the characteristics of plant airconditioning system. Methods: According to this model, the conventional PID control and expert PID controller simulation are performed in the article. The influence of above control methods on the temperature control is summarized by analyzing and comparing the simulation results. Conclusion: Practice has proved that the temperature control method used is reliable and effective.

Background: Nowadays delay locked loops have a very wide range of applications in integrated circuits such as clock recovery circuits, microprocessors, memory circuits, frequency multipliers and synthesizers. Delay locked loops like Phase Locked Loops, mainly aim to synchronize the clock, nevertheless they have a lot of other advantages like high lock speed, unconditional stability, better jitter performance, and lower occupied area with respect to phase locked loops. Methods: In this paper, we evaluate nine structures of analog delay locked loops with wide frequency range, and discuss their embedded techniques to increase and improve frequency range. In this regard, we describe designed blocks like charge pump, voltage controlled delay line, phase detector and start controller circuit. Conclusion: In these structures, in addition to frequency range increase, other parameters like consumption power, jitter, lock time, simplicity and complexity of them are also considered.

Background: Referring to Space-Time Coding (STC) in wireless MIMO communication and Gram-Schmidt procedure, we introduce a new procedure in the symbol combiner of the receiver that detects the transmitted symbols straightforwardly and more easily than the heuristic procedure presented by Alamouti. Methods: To find this combiner, we firstly project the vector of symbols in a two-dimensional orthonormal basis, Cartesian coordinate system, and make the computation in this coordinates. Conclusion: Using the presented procedure, we obtain new capabilities to realize both the new combiner and a reasonable BER in the receiver.

Background: In this paper, the grounded and floating active inductors (GI and FI) employing Voltage Differencing Transconductance Amplifier (VDTA) as an active element are realized. Methods: To demonstrate the performance of both the inductors, two subsequent bandpass filter configurations (BPFGI and BPFFI) have been designed and implemented. The filter BPFGI (BPFFI) is designed at a center frequency of 1.318 (1.318) GHz, bandwidth of 27.32 (31.26) MHz, quality factor of 48.24 (42.16) and figure-of-merit of 82.8 (74.3). The presented configurations are spiral inductor-less and are composed of only transistors grounded capacitors and one resistor, thereby validating their suitability for fully integrated circuit applications. The performances of active inductors and bandpass filters are investigated in the presence of parasitics through sensitivity analysis. Results: The high frequency limitations of proposed inductor configurations have also been presented. Furthermore, the impact of process and environmental variations has also been investigated. Conclusion: To support the theoretical analysis, the simulation of the proposed circuit is done using Virtuoso Analog Design Environment of Cadence @ 45-nm CMOS technology node.