Advanced Materials Research Vols. 433-440

Abstract: This paper addresses the quantized feedback stabilization problem for networked control systems with unbounded process disturbance, where sensors, controllers and plants are connected by digital communication channels. A dynamic logarithmic quantization policy is proposed to stabilize the unstable plant. It is derived that the quantization policy can maintain stabilization in the presence of unbounded and possibly non-Gaussian process disturbance. Simulation results show the validity of the proposed scheme.

Abstract: This paper investigates the input and output quantized control problem for stochastic linear systems with unbounded and possibly non-Gaussian process disturbance, where sensors, controllers and plants are connected by a noisy digital communication channel. Due to the unbounded process disturbance, a dynamic, logarithmic quantization scheme is proposed. An observer-based control policy is presented to stabilize the unstable plant in the mean square sense. Simulation results show the validity of the proposed quantization and control policy.

Abstract: For both ends of the reactor with a parallel transmission lines, a method using Fault-phase voltage of low frequency component to Discrimine of the fault nature in Recovery voltage phase. In this method, different frequency bands is obtained by S-transform for Recovery phase of the faulted phase voltage capacity ,compare the low frequency part , in advance , determining the nature of the fault. Through theoretical analysis and a large number of verification of PSCAD, This method can effectively distinguish the fault type.

Abstract: The reassignment method is a technique for sharpening a time-frequency representation by mapping the data to time-frequency coordinates that are nearer to the true region of support of the analyzed signal. The reassignment method has been proved to produce a better localization of the signal components and improve the readability of the time-frequency representation by concentrating its energy at a center of gravity. But there are still few cross-terms. Then, the empirical mode decomposition is introduced to the reassignment method to suppress the interference of the cross-term encountered in processing the multi-component signals. The multi-component signal can be decomposed into a finite number intrinsic mode function by using EMD. Then, the reassignment method can be calculated for each of the intrinsic mode function. Simulation analysis is presented to show that this method can improve the localization of time-frequency representation and reduce the cross terms. The vibration signals measured from diesel engine in the stage of deflagrate were analyzed with the reassignment method. Experimental results indicate that this method has good potential in mechanical fault feature extraction.

Abstract: Owing to more and more sensitive loads installed in modern ships, ship owners and builders have been faced with rising numbers of complaints about the quality of power. However, the existing power monitoring facilities installed onboard for recording deviations of power parameters is only over steady-state conditions due to limited capacity of measurement equipment and ignores short-duration phenomena. To understand the true supply quality in ships, a power quality (PQ) monitoring technique is employed in this paper. The PQ parameters including short-duration and long-duration voltage and frequency variations in a practical commercial vessel power system under different operating conditions are analyzed and their statistic data are reported. Through PQ measurement and analysis, the quality of supply can be quantified and assessed according to classification society standards. Analysis model developed in this paper can assist them in understanding true supply quality in ships for further determining proper PQ mitigation options.

Abstract: This paper proposes a new all digital phase-locked loop (ADPLL) which operates from 80MHz to 800MHz with the locking cycle of less than 40 clock cycles. It employs a time measurable digital controlled oscillator (TMDCO), which helps the reduction of locking cycle. The proposed ADPLL adopts the (8+4)-bit TMDCO and is very insensitive to its linearity and monotonicity characteristics. The validity of the approach is clearly proved by both the analytic method and spectre simulations in a 90-nm fabrication technology.

Abstract: Rotor position detection is important for motor servo system design. In general, there are two kinds of methods to obtain the position information in real time, sensor or sensorless methods. The sensor methods use position sensors such as optical encoder. This will greatly increase the cost of the system, and the sensor with high precision is difficult to be installed. On the other hand, the sensorless method can reduce the cost, but the reliability and complexity of the algorithm is still the problems. In this paper, a new low-cost integrated position detection unit, which is composed of the integrated position sensor, signal processing hardware and software, is described. The sensor is easy to manufacture and has better precision with the help of signal processing circuit and software based on DSP. The sensor can obtain absolute rotating angle using inductance detection method, and it is originally designed and used for a 2-phase hybrid stepping motor position servo system. Even though the feedback unit is originally designed for a 2-phase hybrid stepping motor, the same unit also can be used with other types of motors.

Abstract: For the purpose of measuring the micro changes of morphological parameters of melon organ, this paper put forth a new algorithm based on mathematical morphology and spline interpolation to obtain the phenotype information of melon such as area and horizontal and vertical diameter and developed a high-resolution non-destructive and contactless measuring system based on vision processing to get the projection area of melon and its diameter. The algorithm is easy to carry out, and can get more ideal edge information than some traditional algorithms. It supplies theoretical basis for revealing the combined response relationship and temporal and spatial variation character between melon morphologies and key environmental factors.

Abstract: Along with the development of the computer and communication technique, the remote monitoring system is widely applied. The pollution source is distributed widely, so the pollution status is difficult to monitoring. The soot concentration remote monitoring system based on GPRS and CAN bus is introduced in the paper. The system adopts the transmission-scattering method to measure the soot concentration. The measurement data is collected by the MCU and sent to the management system through the CAN bus. The data is sent to the EPA through GPRS. The experiment result indicates that the remote monitoring system can on-line measures the soot concentration and improves the communication efficiency and accuracy.

Abstract: A design scheme is proposed in this paper for heat metering remote transmission system based on the Xbee Pro module. Wireless network technology is used in the scheme. A dynamic monitoring, control and transmission network is composed by the wireless network system and the computer in the monitoring and control center. The real-time data detected from heat metering system can be transmitted and monitored. Xbee Pro module and MSP430FW427 single-chip micro-computer are used in the nodes or terminals of the system. The self-provided functions and modules of the components are taken into sufficient consideration in the design to make the system performance as superior as possible and the system structure as simple as possible. In this way, the transmission system with low power consumption and simple structure is achieved.