Automated control system for the fluid distributor of a distillation column with a structured packing

An automated system of acquisition of raw experimental data and a control system for operation modes of an experimental large-scale separation column are described. The influence of a new method of irrigation of a structured packing on the separation column efficiency is studied. Based on the data obtained by the developed automated system, a 20–30% increase in the efficiency of mixture separation on a structured packing is expected.     

SEM stroboscopy for the evaluation of IC operating functions in the subnanosecond range

A stroboscopic system has been applied to the scanning electron microscope (SEM) which operates with an electrostatic deflection system permitting pulse rates up to the GHz region, a value obtained with a very small electrode gap of 100/mum. The deflection voltage was 50 mV for a SEM acceleration voltage of 2.5 kV. The efficiency and limitations of this system are theoretically treated. Such a stroboscopic system has been used for an initial determination of the time interval required for a binary operation of an inverter stage. A delay time of 820 ps was calculated and a time interval of 3.8 ns per binary operation was measured.     

时滞对振动主动控制系统控制效果的影响分析

为解决振动主动控制技术在实际工程应用中反馈环节的时滞会导致受控系统失稳的问题,以获得最优的控制效果,提出了采用逐步输入荷载项的方法,对精细积分方法进行修正,用以求解含双时滞受控系统的动力学方程。通过数值仿真,计算不同时滞情况下的系统响应,在得到不同反馈增益下含双时滞的动力系统响应峰值分布基础上,分析了时滞变化和反馈增益不同的取值对系统响应的影响。研究结果表明,时滞对受控系统控制效果的影响程度随反馈增益的增大而增大,当时滞量和反馈控制增益匹配调节适当时,可以使系统保持稳定状态,该结果可为考虑时滞影响的结构振动主动控制算法的合理设计提供依据。
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Ultrafast photon counting applied to resonant scanning STED microscopy

To take full advantage of fast resonant scanning in super‐resolution stimulated emission depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multigiga sample per second analogue‐to‐digital conversion chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (～50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time‐gated continuous wave STED technology to the usage of resonant scanning with hardware‐based time‐gating. The assembled system provides superb signal‐to‐noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant‐scanning continuous wave STED microscopy with online time‐gated detection.     

A data acquisition system of the FODS setup

A data acquisition system of the focusing double-arm spectrometer (FODS) setup is described. The information from each recording electronic module is read in response to each trigger by an ЛЭ-74 high-speed controller with a buffer memory and is transmitted by a PCI-7200 extension card to the computer memory at the end of the spill. All crates are read in parallel, ensuring a high speed of operation of the system (8000 events per spill for one spectrometer arm). The system is able to read data from different detectors (drift chambers, proportional chambers, calorimeters, Cherenkov radiation ring spectrometer, etc.), possesses a high flexibility, i.e., ensures readout of information for several types of triggers (inclusive, arm coincidence, two particles in one arm, etc.), and enables calibration of detectors in each spill. The software is based on the MIDAS project with an open initial code and allows one to control operation of all detectors during experiments.     

Data taking from multiwire chambers and hodoscopes at IHEP physical setups

The LE-73 and LE-78 modules of MISS system designed for readout and recording of signals from multiwire chambers and hodoscopes are described. The use of an Altera FPGA provides a means for producing different modifications of the modules and adapting their operation to specific requirements of experimental setups. Owing to the availability of a high-speed internal memory, it is possible to design time-to-digital converters with a “common stop” and a 5-ns step and to store data in an internal FIFO memory.     

基于ZigBee的无线振动检测系统设计

针对机械设备的振动信号检测问题,采用ZigBee技术设计了一套无线传感器网络振动检测系统,详细介绍了系统结构,硬、软件设计方案和通信方法。基于Zig Bee技术并结合MEMS传感器开发的无线传感器系统,能够实现无线检测运行机械设备的三轴振动信号,利用Qt框架设计的上位机软件系统可以实现三轴振动信号的波形显示、数据存储以及利用快速傅里叶变换获得的频谱图检测设备的运行状况。实验表明,通过该系统可实时无线检测现场机械设备的振动信号,提高了机械设备故障诊断的自动化水平。     

Passivity-based control framework for task-space bilateral teleoperation with parametric uncertainty over unreliable networks

Bilateral teleoperation systems developed in joint-space or in task-space without taking into account parameter uncertainties and unreliable communication have limited practical applications. In order to ensure stability, improve tracking performance, and enhance applicability, a novel task-space control framework for bilateral teleoperation with kinematic/dynamic uncertainties and time delays/packet losses is studied. In this paper, we have demonstrated that with the proposed control algorithms, the teleoperation system is stable and position tracking is guaranteed when the system is subjected to parametric uncertainties and communication delays. With the transformation of scattering variables, a packet modulation, called Passivity-Based Packet Modulation (PBPM), is proposed to cope with data losses, incurred in transmission of data over unreliable network. Moreover, numerical simulations and experiments are also presented to validate the efficiency of the developed control framework for task-space bilateral teleoperation.     

New high-DQE imaging plate scanner using the reflected readout laser signal for noise corrections

Imaging Plates (IPs) are in principle ideal electron detectors combining a large active layer area with a high sensitivity, linear dynamic range detection over 5 orders of magnitude. A moderate resolution and a decreasing detection quantum efficiency (DQE) for higher electron doses limit their use so far. The decrease of the DQE results from linear noise contributed by readout laser instabilities and inhomogeneities of the IP active layer. Here we present data on a new IP drum scanner prototype. This scanner combines twin channel amplification electronics with a new type of readout laser which allows a smaller readout focus and increased stability. The current nominal pixel size is 25 microm, and the measured modulation transfer function (MTF) indicates that further reduction of the scanning step size down to pixel sizes in the range of 12-15 microm should be possible. A unique feature of the new scanner is the simultaneous recording of the reflected readout laser light. The reflected light signal can be used for a posteriori alignment of repeated scans of one individual IP and for a correction of one part of the high spatial frequency noise contribution (reflected light correction). The posteriori alignment now allows an easy conventional gain normalization of the luminescence signal without using special markers on the IP. Both corrections lead to an increase of the DQE for high electron doses.     

新型轨道自动检测系统研究

近年来,起重机轨道的检测系统测量准确性不高并且效率较低.为了提高现有起重机轨道检测的测量准确性,提高检测效率,提出了一种新型轨道检测系统.在系统中综合使用基站搭载的激光扫描仪,实时追踪小车位置,根据扫描仪采集的数据重构出轨道顶面中心线的空间形状,检测轨道变形程度.系统测量精度可以满足现有标准要求,同时相对于传统检测设备...     

H．264在远程视频监控加工系统中的应用

介绍了数控机床远程视频监控加工系统的基本结构及功能。针对当前制造业远程加工视频传输存在实时性低、图像质量差的突出问题,提出了将高效视频压缩算法H．264应用到远程加工系统。实验结果表明,采用优化的H.264算法实现了视频流的实时传输,改善了制造业加工系统的性能。     

Application of fuzzy adaptive control to a MIMO nonlinear time-delay pump-valve system

In this paper, a control strategy to balance the reliability against efficiency is introduced to overcome the common off-design operation problem in pump-valve systems. The pump-valve system is a nonlinear multi-input–multi-output (MIMO) system with time delays which cannot be accurately measured but can be approximately modeled using Bernoulli Principle. A fuzzy adaptive controller is applied to approximate system parameters and achieve the control of delay-free model since the system model is inaccurate and the direct feedback linearization method cannot be applied. An extended Smith predictor is introduced to compensate time delays of the system using the inaccurate system model. The experiment is carried out to verify the effectiveness of the control strategy whose results show that the control performance is well achieved.     

High-speed download of seismographs using private cloud technology and a proportional integral derivative controller

Seismic exploration is widely used in mining projects. A cable-free self-positioning seismograph has been developed by College of Instrumentation & Electrical Engineering of Jilin University that may collect and store seismic data wirelessly or by Ethernet. When large data sets are produced, data download may affect the schedule of a project. To improve the rate of transfer, a system that allows parallel download of multichannel seismic data is reported here. The system is based on private cloud technology and proportional integral derivative control. A private cloud was employed to provide suitable performance and availability. A proportional integral derivative control algorithm was developed for scheduling to maintain the load balance of the system. The system was employed in a seismic exploration project in Liaoning, China. The average download time of six lines was approximately 1.1 hours, demonstrating that the system reduced download time and enhanced exploration efficiency.     

实时数字微镜哈达玛变换光谱仪的电学结构设计

为了提高数字微镜(digital micro-mirror device,DMD)哈达玛变换光谱仪的编码效率,满足光谱仪大量、实时采集的要求,设计了一种新的DMD哈达玛变换光谱仪的电学结构。将哈达玛编码数据预存到DMD驱动板板载FLASH芯片上,编码时将编码数据读取到DDR2板载内存上,连续播放DMD编码条纹,通过DMD的内同步信号触发光谱采集系统采集光谱数据。实验表明,对511阶哈达玛变换来说,光谱仪的采集时间小于1s,可以满足哈达玛变换光谱仪实时的光谱检测要求,并且其结构还降低了对上位机的依赖,为光谱仪脱离上位机操作奠定了基础。     

First results in studying the readout electronics of the silicon tracking system for upgrading the CLAS12 experiment

Investigations of the readout electronics for the tracking system of the CLAS12 experiment have been performed for the last 2 years. The setup and physical problems of the CLAS12 experiment are described. The silicon detectors designed by the authors for the tracking system of the experiment are considered in brief. The electronic system contains the silicon microstrip detector and FSSR2 integrated circuit, which reads signals from the detector. The FSSR2 chip is described and the principles of the chip architecture intended for processing a time-variable data flow and experimental characteristics obtained on trials of the chip are set forth in brief. Results of simulating the chip throughput under loads expected for the physical experiment and experimental characteristics obtained on trials of this chip are described.     

A drift tracker of the SVD-2 setup

The design and the characteristics of a drift tracker for the SVD-2 setup at the U-70 accelerator of the Institute for High Energy Physics (Protvino, Russia) are described. The drift tracker has been developed to improve the quality of track reconstruction in high-multiplicity events. It is composed of 2304 drift tubes with a diameter of 6 mm and a sensitive region 500–900 mm long. The distance between a track and the anode wire is determined from the drift time. The coordinate resolution and the detection efficiency of the tubes have been determined from the data of the accelerator run in 2006.     

Generators of nanosecond intervals

Block diagrams of two high-stability scanning time-interval generators that can be used to automate tuning and testing of relative-time actuation channels in particle detectors are described. The first generator has the following performance characteristics: an operation range of 0–255 ns, a scan step of 1 ns, and a maximum error of ±0.5 ns. This error remains unchanged within the time of a single scan. The second generator has two operating modes. In the first one (the scan mode), it has an operation range of 50–3000 ns and a scan step of 50 ns. In the second mode, with fixed duration of time intervals, it has an operation range of 50–12 750 ns that can be changed with an increment of 50 ns. The relative error in the duration of the generated interval is 10^?5 s.     

Characteristics of the detecting equipment for the nanosecond tagged-neutron technology

Detecting equipment for the nanosecond tagged-neutron technology has been developed, and its characteristics have been studied. The principles of arrangement and operation of the readout electronics based on the selection of useful events according to specified criteria and data accumulation by a buffer-memory unit with subsequent transfer of data arrays to a remote computer for processing and visualization. The main selection criterion is the presence of signals from α- and γ detectors within the time gate and amplitude ranges in the absence of overlapped events. A prototype of a setup for testing the developed equipment was assembled and experimental studies of its characteristics were performed. The time resolution attained in the recording of α-γ coincidences is 1.0 ± 0.1 ns at an amplitude resolution of the γ detector of 3.6–3.8%. Original Russian Text ? K.A. Balygin, M.D. Karetnikov, A.I. Klimov, K.N. Kozlov, E.A. Meleshko, I.E. Ostashev, G.V. Yakovlev, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 2, pp. 122–132.     

Three-dimensional stability prediction and chatter analysis in milling of thin-walled plate

Stability lobe diagram can be used for selecting proper milling parameters to perform chatter-free operations and improve productivity during milling of thin-walled plates. This paper studies the machining stability in milling of thin-walled plates and develops a three-dimensional stability lobe diagram of the spindle speed, tool position, and axial depth of cut. The workpiece-holder system is modeled as a 2-degree-of-freedom system considering that the tool system is much more rigid than the thin-walled plate, and dynamic equations of motion described for the workpiece-holder system are solved numerically in time domain to compute the dynamic displacements of the thin-walled plate. Statistical variances of the dynamic displacements are then employed as a chatter detection criterion to acquire the stability lobe diagram. The experimentally obtained stability limits correspond well with the predicted stability limits. In addition, influence of feed rate on stability limits is also investigated. By performing frequency analysis of the measured cutting forces to judge if chatter occurs, it is found that feed per tooth has little influence on the stability limits. However, feed per tooth impacts the machined surface quality. The results show that the surface quality drops by increasing feed per tooth.     

QUASAR-370G hybrid vacuum photodetector response to Cherenkov radiation pulses in air

The response of a QUASAR-370G hybrid vacuum photodetector to a Cherenkov radiation pulse in air has been investigated. It is shown that, when the photocathode is wholly illuminated by a Cherenkov radiation pulse with a single-photoelectron intensity and a subnanosecond duration, the time resolution of the photodetector is ??1 ns. In this case, its detection efficiency for Cherenkov radiation is ??7%.