离散广义系统的无振控制

通过讨论离散广义系统中的无振控制以及带有外加扰动的鲁棒控制问题，提出了在Ｅｘ（ｋ）或ｘ（ｋ）不能直接得到时，设计观测器，并采用与众不同的输入ｕ（ｋ）＝ＫＥｘ（ｋ），同时研究了在此输入情况下系统的正则性，分离性，无振控制·

离散广义系统无振控制的几点分析

通过讨论离散广义系统中的无振控制以及带有外加扰动的鲁棒控制问题，提出了在Ex（t）或x（t）不能直接得到时，设计观测器，采用了与众不同的输入u＝kEx（t），同时研究了在此输入情况下系统的正则性，无振控制及分离性．

立式高抛无振浇注深孔桩芯砼的施工方法在山区公路建设中的应用

在山区修建高速公路是改变山区落后面貌造福于民的工程,但是高速公路的修建必然要改变山区原有的自然环境和质态环境,其较之于平原地区高速公路建设尤甚。因而在工程建设之初就要对山区高速公路建设地质、山区高速公路的质量控制做好探讨和规划。所在,在山区公路建设过程汇中,应用适合与其施工的方法,保证山区公路的安全性与长效性。

定量磁共振成像在关节软骨中的应用研究进展

在临床上,关节软骨损伤是一种常见病,其发生发展可由外伤、骨性关节炎(osteoarthritis, OA)以及剥脱性骨软骨炎等原因造成,而且这种损坏发生后很难修复。关节软骨损伤主要表现为关节疼痛及功能障碍,关节软骨的损伤以及退变都不同程度地发生在老年人及长期剧烈运动的人群中。关节镜检查被认为是诊断关节软骨病变的金标准。但由于其有创检查的性质,对检查者的技术水平要求很高,且无法深入了解软骨的内部情况。定量磁共振成像(quantitative magnetic resonance imaging, qMRI)既可显示软骨形态学变化,又可以定量评估软骨的生化成分,由于该技术具有无创、良好的软组织分辨力、多参数、多平面成像的优势,它能以非侵入性的定量测量来敏感地监测软骨的微细变化,提供可靠和可重复的成像生物标志物。

1550nm Polarization-Insensitive Semiconductor Optical Amplifier Based on AlGaInAs-InP

Polarization insensitive AlGaInAs InP semiconductor optical amplifier is realized at a wavelength of 1550nm.The active layer consists of three tensile strained wells with strain 0 40%.The amplifiers are fabricated to ridge waveguide structure with 7° tilted cavity.The two facets are coated with two layers of anti reflection Ti 3O 5/Al 2O 3 films.Residual facet reflectivity is found to be less than 0 03%.The semiconductor optical amplifer exhibits 20dB of signal gain and 7 2dBm of saturation output power with an excellent polarization insensitivity (less than 0 8dB) at 200mA and 1540nm window.

碾压混凝土筑坝施工工艺介绍

碾压混凝土筑坝速度快、工期短、投资省、在世界各国发展迅速,尤其是美、英、日3国,我国也在葛州坝、坑口、岩滩等水站工地了作试验,取得一定,成绩本文就辗压筑混凝土坝的施工工艺方面进行介绍。

New atom movement mechanism for tracking path on disordering AuCuI(A_8^(Au)A_4^(Cu)) compound

Taking experimental path on disordering AuCuI（AAuCu8A4）composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I（AAu Cu8 A4）to keep structure stabilization against changing temperature is attributed to the fact that the AAu8 and ACu4 potential well depths greatly surpass their vibration energies, which leads to the subequilibrium of experimental path. A new atom movement mechanism of AuCuI（AAuACu84）to change structure for suiting variation in temperature is the resonance activating-synchro alternating of alloy genes, which leads to heterogeneous and successive subequilibrium transitions. There exists jumping order degree, which leads to the existence of jumping Tj-temperature and an unexpected so-called ＂retro-effect＂ about jumping temperature retrograde shift to lower temperatures upon the increasing heating rate. A set of subequilibrium holographic network path charts were obtained by the experimental mixed enthalpy path method.

An Improved On-Chip CMOS Astable Multivibrator

An improved on-chip CMOS astable multivibrator is proposed, which overcomes the shortcomings of the traditional one that the signal duty-cycle is depending on model parameters, and generates stable clock signal with duty-cycle equaling 50%. The latch-up effect has been prevented on the improved circuit. It is extremely important that all the excellent performances of the improved astable multivibrator have been achieved with a dynamic power consumption equaling its predecessor one. The advantage of the structure has been verified by SPICE simulation.

Key Techniques of Frequency Synthesizer for WLAN Receivers

Several key techniques for a PLL-type frequency synthesizer for WLAN receivers are studied. Its structure is analyzed and the main parameters are proposed. A monolithic LC-tuned voltage controlled oscillator （LCVCO） with low phase noise is fabricated with TSMC 0.18μm RF （radio frequency） CMOS technology. The measured phase noise is - ll7dBc/Hz at 4MHz off the center frequency of 4. 189GHz. A down-scaling circuit with low power dissipation was fabricated in a TSMC 0.18μm mixed-signal CMOS process. The measured results show that the IC can work well under a 1.8V power supply. Its total power dissipation is only 13mW.

Integrated Low-Power CMOS VCO and Its Divide-by-2 Dividers

An integrated low power CMOS VCO and its divide by 2 dividers for WLAN transceivers are presented.The VCO is based on on chip symmetrical spiral inductor and differential diode and the divide by 2 dividers are based on the ILFD technique.Due to differential LC tanks and ILFD techniques,power consumption is low.The circuit is implemented in a 0 18μm CMOS process.Measurements show the proposed circuit could produce 3 6/1 8GHz dual band LO signals with a wide tuning range and low phase noise.1 8GHz LO signals are quadrature.It consumes 5mA at V DD =1 5V.The size of die area is only 1 0mm×1 0mm.

Trajectory tracking and obstacle avoidance method for robots based on fast terminal sliding mode

For accurate trajectory tracking and obstacle avoidance in finite time of a nonholonomic mobile robot,a trajectory tracking controller based on global fast terminal sliding mode method is proposed,which has the advantages of chattering-free and adjustable convergence time.First of all,the kinematics model of the robot is established in mobile carrier coordinates.Secondly,the global structure including terminal attractor and exponential convergence of the fast terminal sliding mode trajectory tracking controller is proved by Lyapunov stability theory,ensuring that the trajectory and heading angle tracking error converges to a smaller zero range in finite time.Finally,the artificial potential field obstacle avoidance method is introduced to make the robot not only track the reference trajectory strictly,but also avoid the obstacles.The simulation results show that the proposed method can achieve a stable tracking control in finite time for a given reference trajectory.

Vibration Suppression Analysis for Supporter with Constrained Layer Damping

By analyzing the correlation between modal calculations and modal experiments of a typical supporter, an effective finite element analysis( FEA)model of the actual aerospace supporter is created. According to the analysis of constrained viscoelastic damping, the strategies of PVC have been worked out, and the correlation between modal calculations and modal experiments of the supporter has also been computed, and then, an experiment has been designed based on the calculation results. The results of experiments verify that the PVC strategy can effectively suppress vibration.

Study on structural and compositional transitions of coal ash by using NMR

Structural and compositional transitions of Datong coal ash and its CaCO3 additional effects were carefully exam- ined at a temperature range of 300 to 1 600℃ by using XRD and solid state NMR. The quantitative estimation of amorphous structures of ashes can be successfully obtained through the analyses of solid state NMR spectra. Viscosity of molten ash and its changes with CaCO3 addition were also evaluated up to 1 700 ℃ by using a rotary type viscometer. Glasses with poor crystalline and amorphous phase were continuously formed through the eutectic reaction of silica above fusing temperature （FT〉1 500 ℃） that caused broadening and shift of 29Si and 27A1 peaks in NMR results. With the additional amount of CaCO3 increasing, the peaks shifted to downfield obviously; the fraction of Si（OA1）0（OSi）4 decreased, while that of Si（OA1）l（OSi）l at 84.3 x 10-6 increased apparently. These transitions indicated the destruction of large alumina-silicate framework into small segments by the addition of Ca ion.

Middle range wireless power transfer systems with multiple resonators

The equivalent two-port network model of a middle range wireless power transfer(WPT) system was presented based on strongly coupled multiple resonators. The key parameters of the WPT system include self-inductance, resistance, parasitic capacitance, mutual inductance and S-parameters of coils & resonators were analyzed. The impedance matching method was used to optimize load power and transmission efficiency of the multi-resonator WPT system, and the impedance matching method was realized through adjusting the distances between the coils and resonators. Experiments show that the impedance matching method can effectively improve load power and transmission efficiency for middle range wireless power transfer systems with multiple resonators, at distances up to 3 times the coil radius with efficiency more than 70% and load power also close to 3.5 W.

Delamination Damage Detection in Laminated Composite by LDR-Based Multi-frequency Method

Local defected resonance(LDR)is a recently-developed non-destructive testing method,which identifies damage by detecting the vibrational response of the structural surface under the wideband ultrasonic excitation. The concept of LDR is studied and applied for damage imaging of delamination in composite laminates. Aiming at the problem of poor anti-noise ability and inaccurate damage identification in traditional detection process,an LDR-based multi-frequency method is proposed. Experimental results show that the proposed method can realize the localization and imaging of delamination damage in composite materials.

Deriving Vibration Modes of Semi-infinite Chain Model by “Invariant Eigen-operator”Method

For the first time, we introduce a fully quantum mechanical Hamiltonian for a semi-infinite chain model of atoms. We then derive the vibration modes of this model by virtue of the ＂invariant eigen-operator＂ method in two different cases, which is concise and revealing.

One-Branch Zero-IF Wireless Receiver Topology with Multiphase Local Oscillator

This paper proposes a one-branch zero-IF receiver topology, which samples the I and Q signals of the modulated RF carrier with one signal path by means of a multiphase local oscillator. The suggested one-branch re- ceiver works without matching problem, and it is also capable of cancelling out the flicker noise and DC-offset when the local oscillator is configured to the four-phase mode. The one-branch receiver saves much area and power com- pared with the traditional two-branch ones. All of the advantages above make the one-branch receiver topology a promising architectural candidate for low-power and low-cost RF CMOS receiver designs. Keywords： RF CMOS; zero-IF; flicker noise; image rejection; low-power; IQ matching

Stability Improvement of Power System by Using PI ＆ PD Controller

This paper presents the model of a SVC （Static VAR Compensator） which is controlled externally by a PI （Proportional Integral） ＆ PD （Proportional Differential） controllers for the improvements of voltage stability and damping effect of an on line power system. Both controller parameters has been optimized by using Ziegler-Nichols close loop tuning method. Both single phase and three phase （L-L） faults have been considered in the research. In this paper, a power system network is considered which is simulated in the phasor simulation method ＆ the network is simulated in four steps; without SVC, With SVC but no externally controlled, SVC with PI controller ＆ SVC with PD controller. Simulation result shows that without SVC, the system parameters become unstable during faults. When SVC is imposed in the network, then system parameters become stable. Again, when SVC is controlled externally by PI ＆ PD controllers, then system parameters becomes stable in faster way then without controller. It has been observed that the SVC ratings are only 50 MVA with controllers and 200 MVA without controllers. So, SVC with PI ＆ PD controllers are more effective to enhance the voltage stability and increases power transmission capacity of a power system. The power system oscillations are also reduced with controllers in compared to that of without controllers. So with both controllers the system performance is greatly enhanced.

用振动解析法对回转机械进行非解体诊断

滚动轴承损伤是牵引电动机的常见故障之一。本文介绍用振动解析法对牵引电动机轴承进行非解体故障诊断的测试原理、仪表构成、计算方法及判断技术。阐明了简易振动诊断和精密振动诊断的功能和特征。详细说明了通过包络线处理和快速傅利叶转换(FFT)而获得的不同类型振动特性曲线的特点和缺陷识别方法。最后还介绍了一台日本MG型牵引电动机轴承故障分析诊断实例。