轻型卷扬机用定程器进行限位控制

为更好地解决卷扬机、电动葫芦等设备在使用中的安全保险问题,本文论述了采用不同设计原理的定程器是如何在升降、牵引等方面进行限位控制的.该控制装置是机电一体,其机械部分可分别运用螺旋传动、蜗杆传动、行星轮系传动获得大传动比;而电控部分是通过四接点行程开关将机械限位动作用于转控报警装置及电机主电路.

Relocation method of microseismic source in deep mines

A new method, named relocation, was proposed to reduce the impact of sensor errors systematically, especially whenavailable data of sensors are abundant. The procedure includes evaluating the reliability of every sensors datum, processing the initiallocation by the credible data, and selecting a set of equations with optimal noise tolerance according to the relative relationshipbetween the initial location and sensors location, then calculating the final location by k-mean voting. The results obtained in thisresearch include comparing traditional location method with the presented method in both simulation and field experiment. In thefield experiment, the location error of relocation method reduced 41.8% compared with traditional location method. The resultssuggested that relocation method can improve the fault-tolerant performance significantly.

珠宝业的自动化宝石加工

西德鲁克斯公司(LUX ＆ CO)备有几种半自动和全自动的宝石翻光面机械设备,各具不同类型磨削和抛光盘(轮),它们有两个、四个、六个、或八个支座,用于安装多头宝石基座,每小时最多能切割2000枚宝石。

Research on High-Accuracy Programmable Timer Used in Acquiring UWB Signals

UWB signal digitization depends, to a large extent, on the accuracy of sampling time. A highaccuracy programmable timer is therefore the key to implementing UWB signal data acquisition. A high-accuracy programmable timer based on the principle of ramp generators is described in this paper. The counting range of the timer is up to 16 bits, the timing precision is 8 ps, and the equivalent sampling rate is up to 50G Hz. No other identical product has been reported so far. This timer was successfully used in the data acquisition system for geological radar signals developed by us.

Design of dead reckoning system for mobile robot

A dead reckoning system for a wheeled mobile robot was designed, and the method for robot’s pose estimation in the 3D environments was presented on the basis of its rigid-body kinematic equations. After analyzing the locomotion architecture of mobile robot and the principle of proprioceptive sensors, the kinematics model of mobile robot was built to realize the relative localization. Considering that the research on dead reckoning of mobile robot was confined to the 2 dimensional planes, the locomotion of mobile robot in the 3 coordinate axis direction was thought over in order to estimate its pose on uneven terrain. Because the computing method in a plane is rather mature, the calculation in height direction is emphatically represented as a key issue. With experimental results obtained by simulation program and robot platform, the position of mobile robot can be reliably estimated and the localization precision can be effectively improved, so the effectiveness of this dead reckoning system is demonstrated.

Control of Multiple PWM Servos by a Single Programmable Timer

An algorithm for control of several servo motors by a mi- crocontroller is presented. The limited ntanber of progranunable timers on the majority of micnocntrollers presents a problem for multiple generation of timing pulses. Two software approaches are discussed in the paper and experimental results given for operation of a set of small servos using a single timer.

Modulation instability of dispersion-shifted fiber couplers

The nonlinear coupled-mode equations are rewritten by even and odd modes.We study modulation instability(MI) of dispersion-shifted fiber couplers when either even or odd mode is launched alone by using zero-dispersion wavelength relatively long(quasi-cw) pulses.The result shows that there are new types of MI in both the normal-dispersion and the anomalous-dispersion regimes.MI is concerned with forth-order dispersion and has no relation with third-order dispersion.Quasi-cw can be changed into pulses array under certain conditions.We can extract super short pulse from this.Furthermore,the bandwidth of gain spectra widens and its strength accretes as the input power increases.

Determination of Precise Instantaneous Height at Multibeam Transducer

To overcome the shortcomings of the traditional multibeam survey and data processing, a new method is presented for the precise determination of the instantaneous height at the multibeam transducer by the blend of GPS height and heave signals. Before signal blend, GPS height and heave signals need to be corrected first to the transducer center by attitude correction. Second, the GPS height needs to be checked and modified by heave check and modification itself. Butterworth and FFT （fast Fourier transformation） were used in the signal blend. Finally, FFT is thought to be appropriate in signal processing. The new method efficiently overcomes the shortcomings of the traditional method, and this is proven well by the MBS （multibeam bathymetric system） experiment.

The research of feet pressing energy collection and utilization device --based on piezoelectric ceramics

After people or vehicles press, piezoelectric ceramics can send a weak and unstable alternating current. According to this characteristic, we made feet pressing energy collection and utilization device based on piezoelectric ceramics. The two parts of this device includes energy storage and utilization. In terms of storage, the energy collection module, can deposit AC sent by piezoelectric ceramics in the super capacitor after rectification. In terms of utilization of energy, the device achieve a variety of usage： through the USB interface, it can supply power for different equipments, replace the mobile station of train stations and realize the function of saving the electricity as the night corridor induction lamp, combined with vibration module design and programmable timer. The whole structure is supported by an acrylic plate, which saves cost and have good durability. This device implements the storage and usage of idle feet pressing energy. In conclusion, it is helpful to provide a new idea for people＇ s low carbon lives and has a quite broad application prospect.

Conservation Law Classification and Integrability of Generalized Nonlinear Second-Order Equation

This paper is concerned with the generalized nonlinear second-order equation.By the direct construction method,all of the first-order multipliers of the equation are obtained,and the corresponding complete conservation laws(CLs) of such equations are provided.Furthermore,the integrability of the equation is considered in terms of the conservation laws.In addition,the relationship of multipliers and symmetries of the equations is investigated.

Trajectory planning and tracking control for underactuated unmanned surface vessels

The trajectory planning and tracking control for an underactuated unmanned surface vessel(USV) were addressed.The reference trajectory was generated by a virtual USV,and the error equation of trajectory tracking for underactuated USV was obtained,which transformed the tracking and stabilization problem of underactuated USV into the stabilization problem of the trajectory tracking error equation.A nonlinear state feedback controller was proposed based on backstepping technique and Lyapunov's direct method.By means of Lyapunov analysis,it is proved that the proposed controller ensures that the solutions of closed loop system have the ultimate boundedness property.Numerical simulation results are presented to validate the effectiveness and robustness of the proposed controller.

Dosimetric evaluation of a beam matching procedure

Objective: The dosimetric characteristics for linear accelerators with the same model, and nominal energy are known to be very similar, as long as the machines are unaltered from the manufacturer's original specifications. In this preliminary study, a quantitative investigation of the similarity in the basic photon and electron dosimetry data from the Siemens Oncor linear accelerators at our hospital(Children's Cancer Hospital, Cairo, Egypt) was reported. Methods: The output factor(OF), wedge factors(WF), percentage depth dose(PDD), and beam profile for the 6 and 10 MV photon beams were measured. Results: The measured output factors varied by less than about 1% for each field size. The difference between the maximum and minimum PDD values at each depth was less than about 1%. The difference between the beam flattnes and symetry was no more than 1% at all off-axis distances. For electron the results showed that the PDD, OF, and the beam profiles were matched within 1% differences. Conclusion: These results strongly suggest that it is feasible to establish one reference photon and electron dosimetry data set for the two machines and nominal energies.

Television Programs for Teenagers and the Use of Multimodality in Knowledge Popularization

The aim of this work is to study the interaction of spoken words and images that are used within programs targeted to popularize knowledge among teenagers. We will look into the program Bit@bit developed by Television de Catalunya, which is intended to disseminate computer concepts, tools and procedures. In this kind of program, one can find spoken language （on/off screen voices, interviews, etc.）, other oral material （sounds, music, songs）, written language （descriptions, title sequences, inserts and Uniform Resource Locator, or electronic addresses）, and other visual material （film cut images, advertising, other TV programs, cartoons, films, both location or studio images, depicting reality, or computer screens, or logotypes）. The profusion of multimodal elements used in this program helps to keep the young audience＇s attention. The use of references to their world or knowledge, as a target group, is based on interplay among different semiotic strategies. At the same time, the entire program＇s multi-segmentation into short video clips, combined with a fast paced sound track helps its audience to understand the specialized explanations presented. Of all the multimodal wealth that the program presents, we will concentrate only on the relationship between the words and the images （leaving other secondary semiotics to one side）, the main strategy for achieving the objective of transmitting knowledge and winning adolescent audiences.

A robust multi-objective and multi-physics optimization of multi-physics behavior of microstructure

A new strategy is presented to solve robust multi-physics multi-objective optimization problem known as improved multi-objective collaborative optimization （IMOCO） and its extension improved multi-objective robust collaborative （IMORCO）. In this work, the proposed IMORCO approach combined the IMOCO method, the worst possible point （WPP） constraint cuts and the Genetic algorithm NSGA-II type as an optimizer in order to solve the robust optimization problem of multi-physics of microstructures with uncertainties. The optimization problem is hierarchically decomposed into two levels： a microstructure level, and a disciplines levels, For validation purposes, two examples were selected： a numerical example, and an engineering example of capacitive micro machined ultrasonic transducers （CMUT） type. The obtained results are compared with those obtained from robust non-distributed and distributed optimization approach, non-distributed multi-objective robust optimization （NDMORO） and multi-objective collaborative robust optimization （McRO）, respectively. Results obtained from the application of the IMOCO approach to an optimization problem of a CMUT cell have reduced the CPU time by 44% ensuring a Pareto front close to the reference non-distributed multi-objective optimization （NDMO） approach （mahalanobis distance, D2M =0.9503 and overall spread, So=0.2309）. In addition, the consideration of robustness in IMORCO approach applied to a CMUT cell of optimization problem under interval uncertainty has reduced the CPU time by 23% keeping a robust Pareto front overlaps with that obtained by the robust NDMORO approach （D2M =10.3869 and So=0.0537）.

On Stabilizing Sets of PI Controllers for Multiple Time Delayed Process

This paper considers the problem of stabilizing multiple time delayed processes using proportional integral(PI) controller.The presented approach is based on finding all possible values of control parameters which will result in pure imaginary roots of closed loop characteristic equation under all process parameters fixed.The ergodic search of three PI control parameters are converted from the range of infinity to finite range by introducing trigonometric tangent function.After all possible stability boundaries are obtained,the Nyquist stability method is used to determine the actual stability region of the controller parameters.This method also permits design for simultaneous minimum gain and phase margin requirement.An illustrative example case is also presented.

Design and Implementation of Image Acquisition System Based on STM32

In order to solve the difficulty of reading inconvenience in the measurement process of digital track gauge, a kind of image data acquisition system with low cost and stable performance is designed. The system uses the Cortex-M4 as the core of the STM32F407ZGT6 as the control core, the use of OV2640 as an image sensor to collect images, and the collection of image files stored in the SD card for subsequent image processing to achieve the goal of rail adjustment to lay the foundation. The experimental results show that the image acquisition is stable and refiable and the collected images are clear and meet the design requirements.

Stress Analysis of the Sarafix External Fixator Design

A stress analysis of the Sarafix external fixator design was performed using finite element analysis （FEA） and experimental tensometric measurements. The study was conducted at one of the Sarafix fixator configurations that have a clinical application in the treatment of tibia fractures. The intensity of principal and yon Mises stresses generated at two measuring points （MP） on the fixator connecting rod were monitored and analyzed during the testing on axial compression on the fixator design and its finite element model （FEM）. The 3D geometrical and FEM model of the fixator was formed using the computer aided design/computer aided engineering （CAD/CAE） software system CATIA. Verification of the results for the dominant principal stresses obtained from FEA was carried out through tensometric measurements. The measuring chain consisted of strain gauges connected into two Wheatstone half-bridges, digital measuring amplifier system and a computer with software for acquisition and monitoring of measurement results. A quite good agreement was observed between the results obtained on the basis of FEA and results of experimental tensometric analysis,

Optimum High-Quality Ceramic Support like SiC, AI203 ＆ TiO2 for Cobalt as a Very Active Metal for Fisher-Tropsch-Synthesis in a Fixed Bed Reactor Configuration

A series of experiments were performed on indigenously synthesized catalyst pallets of cobalt as a very active metal on ceramic support like SiC, A1203 ＆ TiO2 in a fixed bed reactor configuration with an aim to study the catalyst activity ＆ selectivity, chemical kinetics, design flexibility, temperature, pressure by characteristics diffusion distance. Catalyst pallets were prepared and then characterized by N2 adsorption, X-ray Diffraction, Scanning Electron Microscope, and Temperature Programmed Reduction. The results showed the Brunaner, Emmett and Teller area of SiC was the lowest among the three supports prepared for testing. However, its reducibility showed improvement with use of cobalt acetate, as a precursor, rather than cobalt nitrates. Mechanical strength and behavior was checked by the hardness testing machine. Fischer Tropsch （FT） synthesis experiments were performed in the fixed bed reactor set at 450-500 K and 2.3-2.5 MPa using synthetic gas having HJCO ration = 2.0. FT synthesis showed that cobalt/silicon carbide catalyst gives high CO conversion and lower methane selectivity, compared to Co/A1203 and Co/TiO2, as well as high C5＋ selectivity of almost 90%. Moreover, its stability was enhanced by the addition of Zr02, as without this addition, the Co/SiC interactions are weaker and can cause carbon sintering, and thus, the deactivation rate to increase.

Cavitation shedding dynamics around a hydrofoil simulated using a filter-based density corrected model

The unsteady turbulent cloud cavitation around a NACA66 hydrofoil was simulated using the filter-based density corrected model(FBDCM). The cloud cavitation was treated as a homogeneous liquid-vapor mixture and the effects of turbulent eddy viscosity were reduced in cavitation regions near the hydrofoil and in the wake. The numerical results(in terms of the vapor shedding structure and transient pressure pulsation due to cavitation evolution) agree well with the available experimental data, showing the validity of the FBDCM method. Furthermore, the interaction of vortex and cavitation was analyzed based on the vorticity transport equation, revealing that the cavitation evolution has a strong connection with vortex dynamics. A detailed analysis shows that the cavitation could promote the vortex production and flow unsteadiness by the dilatation and baroclinic torque terms in the vorticity transport equation.