Energy storage unit: Solid state demonstrators at 20 K and 6 K

Cryocoolers’ vibrations prevent them from being used in some sensitive applications. Stopping the cryocooler even for a short period gives rise to a steep drift of temperature. Such a drift can be significantly attenuated by adding an enthalpy reservoir to the cryocooler, separated from its cold finger by a heat switch. The whole assembly for the enthalpy reservoirs and switch is here called ESU, the energy storage unit. Two units have been built and tested based on solid state materials. One unit was designed to work up to 20 K, the other up to 6 K. This paper presents the experimental results obtained for both ESUs.Lead was used for the 20 K ESU while the ceramic GOS (Gd₂O₂S) was found adequate for the 6 K ESU. After stopping the cryocooler, a fairly slow temperature drift was measured at each ESU (from 11 to 20 K or from 3 to 6 K, respectively) while applying 10 mW for one hour, for instance. Otherwise, a temperature controlled platform experiment can use an ESU as a cold source allowing a constant temperature. Input power to the ESUs was monitored along with temperature and time. In the case of the 20 K ESU, calculations match the stored amount of energy as well as the temperature drift of the energy reservoir.A study for a high enthalpy intercept at the middle of the switch is also presented here. This intercept shall allow the attenuated temperature drift to hold for longer times. A cryogenic experiment can then be carried on using a cryocooler in a completely silent environment.     

高谐波抑制性能的射频高功率校准系统

This paper deals with instrumenting a mechatronic system, through the incorporation of suitable sensors, actuators, and other required hardware. Sensors (e.g., semiconductor strain gauges, tachometers, RTD temperature sensors, cameras, piezoelectric accelerometers) are needed to measure (sense) unknown signals and parameters of a system and its environment. The information acquired in this manner is useful in operating or controlling the system, and also in process monitoring; experimental modeling (i.e., model identification); product testing and qualification; product quality assessment; fault prediction, detection and diagnosis; warning generation; surveillance, and so on. Actuators (e.g., stepper motors, solenoids, dc motors, hydraulic rams, pumps, heaters/coolers) are needed to “drive” a plant. Control actuators (e.g., control valves) perform control actions, and in particular they drive control devices. Micro-electromechanical systems (MEMS) use microminiature sensors and actuators. MEMS sensors commonly use piezoelectric, capacitive, electromagnetic and piezoresistive principles. MEMS devices provide the benefits of small size and light weight (negligible loading errors), high speed (high bandwidth), and convenient mass-production (low cost). The process of instrumentation involves the identification of proper sensors, actuators, controllers, and signal modification/interface hardware, and software with respect to their functions, operation, parameters, ratings, and interaction with each other, so as to achieve the performance requirements of the overall system, and interfacing/integration/tuning of the selected devices into the system, for a given application. This paper presents the key steps of instrumenting a mechatronic system, in a somewhat general and systematic manner. Examples are described to illustrate several key procedures of instrumentation.     

The transport of discrete solids in above ground near horizontal drainage pipes: A wave speed dependent model

The satisfactory transportation of waste solids away from habitable spaces is an important factor in the assessment of a drainage design. Waste solids in building drainage systems may still be considered as discrete, subject to a system of forces including hydrostatic, mass, buoyancy and frictional components. Historical difficulties in measuring solid velocity have been addressed with the design of an innovative measuring system based on an infra-red pick-up device. A series of empirically derived expressions were developed to describe single solid transport in any flow regime based on the Mach number of the solid in the surrounding flow.     

Modelling and instrumentation of the storm overflows of the combined sewer system of Sélestat

For several years now, combined sewer overflows (CSOs) have been subject to regulations relating to the monitoring of discharge. This paper shows that ultrasound instrumentation of CSOs is both fundamentally possible and practically useful. The contribution of 1D and 3D modelling is necessary to select the location of sensors and to determine the overflow law. Current modelling tools are sufficiently developed to characterize the hydraulic phenomena involved in such storm overflows. Simulation results allow instrumentation to be relevant for both the installation of sensors and the processing of results.     

An instrument for detecting arbitrary peaks and troughs of a fluctuating stress signal

An instrument has been developed to detect arbitrary peaks and troughs of a fluctuating stress signal. This information is used to perform a fatigue life prediction. The instrument uses an analogue method of detecting peaks and troughs. This is considered to be cheaper and faster than the digital alternative. A microprocessor was employed to read peak/trough values from seven such channels and perform a 'rainflow' cycle count of the stress histories. The equipment has been tested on the Humber Suspension Bridge and has been shown to work satisfactorily.     

核电站数据采集系统的设计

核电站对于仪控系统的性能要求很高.目前国内核电站的仪控系统大多以模拟控制为主,数据显示精度和自动化程度都比较低.秦山三期核电站停堆系统中应用的数据采集系统,将国产集散控制系统(DCS)技术引入核电站,实现了快速数据采集、记录、报警、查询、显示等功能.     

In vessel neutron instrumentation for sodium-cooled fast reactors: Type,lifetime and location

The in vessel instrumentation of sodium-cooled fast reactors must deliver measurements that are reliable and easy to interpret over several reactor cycles in order to fulfill the safety requirements. This paper compares, with respect to this requirement, three types of detectors that are widely used in neutron measurements: fission chambers, boron-lined proportional counters, self-powered neutron detectors. We use neutron spectra that are computed for preliminary design of sodium-cooled fast reactor in different representative locations: in diluting tubes within nuclear fuel assemblies, or in the lateral neutron protections. With an evolution code, we compute the expected signal for each type of detector, to assess whether its level is sufficient, and also its evolution over three operating cycles, to examine whether it is compatible with long term measurements. The conclusion is that fission chambers are the only type able to deliver an interpretable signal for a wide dynamic of reactor power and for three or more operating cycles. The two other types are shown to be inadequate.     

天然气中硫化氢的激光吸收光谱法在线分析

硫化氢具有强烈的毒性和腐蚀性,为了贯彻实施新的国家天然气标准,增强含硫天然气生产的安全性,提高生产效益,对含硫天然气气质的在线监测,尤其是硫化氢含量的监测就显得非常重要。但现有的测量方法或者精度不高,或者操作复杂、运行维护困难。为此,提出了基于可调谐半导体激光器吸收光谱技术（TDLAS）的在线硫化氢分析方法,并采用波长调制（WMS）技术减少杂质的影响和提高测量精度,试制了测量范围为1 000～20 000 μmol/mol的在线分析系统。离线标定和在线测试结果表明该系统最快响应时间仅0.25 s,最大测量误差为1.3%。在川东北某含硫气井进行了较长时间的在线测量,结果显示该系统稳定可靠。结论认为,该系统具有维护成本低和操作方便简单等特点,它的成功运用,有望弥补现有方法的不足,为我国高含硫天然气的安全开采服务。     

基于虚拟仪器的计算机视觉系统的研究

伴随PCI总线及MMX技术的出现，基于PC或工作站的计算机视 觉系统的实用领域日益扩大。本文对视觉系统的实现进行了研究与技术分析，研究开发了基 于虚拟仪器的种子等级判别视觉系统，并论述了数字图像处理算法的应用。