Adsorption from solutions in a centrifugal field and a device for studying it

A device is proposed for studying adsorption in a centrifugal field. Using this device, it is possible to introduce a sorbent into a reactor with an adsorbate directly during centrifugation. The device is composed of a dispenser built into the reactor lid and a command/reception system with an IR communication channel. The dispenser contains a hopper for loose material with a bottom door and a locking mechanism that keeps the door closed during centrifugation. In response to the command to unload the hopper, the reception part of the electronic circuit melts the thermoplastic thread that holds the rod and the hopper door at the bottom of the hopper, and the sorbent falls into the reactor.     

Testing facility for hydrogen storage materials designed to simulate application based conditions

For the daily use of hydrogen storage materials, not only their intrinsic storage properties are important, but also equally important is the performance under practical conditions. Besides the techniques already available for the fundamental characterization of storage materials, there is a growing need to test storage materials under conditions resembling day-to-day use. For that we developed and tested a downscaled hydrogen storage reactor with which it is possible to monitor the hydrogenation behavior under nonideal conditions. Here we present a characterization of the developed reactor setup which enables a fast screening of storage materials. For characterization and calibration purposes, we use the rather well-documented LaNi(5)-Al alloy as reference. The found experimental results agree well with the properties of LaNi(5)-Al as reported in literature. Our results show that this reactor setup enables an efficient screening of new developed storage alloys under realistic conditions and is therefore complementary to the already existing characterization setups.     

Theoretical and experimental investigations of neutron and γ-ray spectra and doses in the experimental room of the ГИР-2 reactor

A mathematical model of the ГИР-2 reactor core and its experimental room is described. Neutron spectra and absorbed doses at different points in the room, calculated using the Monte Carlo method, are presented. By comparing these results to experimental data, it is shown that the model proposed can be used to calculate the main characteristics of the reactor radiation field with an accuracy of no worse than 40%.     

Micro-reactors for characterization of nanostructure-based sensors

Fabrication and testing of micro-reactors for the characterization of nanosensors is presented in this work. The reactors have a small volume (100 μl) and are equipped with gas input/output channels. They were machined from a single piece of kovar in order to avoid leaks in the system due to additional welding. The contact pins were electrically insulated from the body of the reactor using a borosilicate sealing glass and the reactor was hermetically sealed using a lid and an elastomeric o-ring. One of the advantages of the reactor lies in its simple assembly and ease of use with any vacuum/gas system, allowing the connection of more than one device. Moreover, the lid can be modified in order to fit a window for in situ optical characterization. In order to prove its versatility, carbon nanotube-based sensors were tested using this micro-reactor. The devices were fabricated by depositing carbon nanotubes over 1 μm thick gold electrodes patterned onto Si/SiO(2) substrates. The sensors were tested using oxygen and nitrogen atmospheres, in the pressure range between 10(-5) and 10(-1) mbar. The small chamber volume allowed the measurement of fast sensor characteristic times, with the sensors showing good sensitivity towards gas and pressure as well as high reproducibility.     

循环式多级超声波反应釜储液槽有限元分析

针对普通超声波反应釜对某些反应效果不好的问题,设计了循环式多级超声波反应釜储液槽的结构,在考虑了储液槽安全性和系统稳定性等问题的基础上,首先对储液槽温度场和受力作了理论分析,再利用有限元分析软件ANSYS对其温度场分布和槽壁受力作了模拟。研究结果表明,储液槽内温度在同一水平面上相等,随着高度增加,温度越来越低,其顶部温度最低,材料热变形最小,符合设计要求;同时软件分析结果表明,对于给定的压力远远小于槽壁的强度,其影响可以忽略不计,符合循环式多级超声波反应釜储液槽要求。     

Examination of flame length for burning pulverized coal in laminar flow reactor

Because there has been a recent increase in the use of low calorific coal compared to standard coal, it is crucial to control the char flame length governing the burning life-time of coal in a coal-fired utility boiler. The main objective of this study is to develop a simplified model that can theoretically predict the flame length for burning coal in a laboratory-scale entrained laminar flow reactor (LFR) system. The char burning behavior was experimentally observed when sub-bituminous pulverized coal was fed into the LFR under burning conditions similar to those in a real boiler: a heating rate of 1000 K/s, an oxygen molar fraction of 7.7 %, and reacting flue gas temperatures ranging from 1500 to 2000 K. By using the theoretical model developed in this study, the effect of particle size on the coal flame length was exclusively addressed. In this model, the effect of particle mass was eliminated to compare with the experimental result performed under a constant mass feeding of coal. Overall, the computed results for the coal flame length were in good agreement with the experimental data, particularly when the external oxygen diffusion effect was considered in the model.     

一种基于大视野的微操作系统的目标定位方法

针对微操作系统中位于视野之外的操作对象的任意性,提出了一种对显微镜视野之外操作对象的自动定位方法,实验证明,该方法能将操作对象自动移至显微镜视场内,可提高工作效率,提高自动化程度。     

High-temperature and high-pressure pulsed synthesis apparatus for supercritical production of nanoparticles

In materials science continuous flow supercritical fluid reactors are widely used for highly controlled synthesis of nanoparticles. The major limitation of continuous flow reactors is that the inherent distribution of residence times leads to broadening of the corresponding size distribution of the nanoparticles, and in addition it is not possible to carry out synthesis with very short or very long reaction times. Here, we report a new synthesis concept that we call pulsed synthesis, which removes the limitations of flow synthesis at the expense of a more complex reactor design and extensive computer control. Another limitation of flow synthesis is that it is largely a black box, where limited direct information is available of the specific chemical reactions taking place, the particle nucleation, the particle growth, etc. Such information is commonly obtained from in situ synchrotron and neutron scattering studies, but transfer of information from in situ studies with static reactors to laboratory flow reactor conditions is highly non-trivial. The new pulse reactor provides superior heating rates, arbitrary residence times with narrow distribution limited only by the pulse duration, and the ability of using the same reactor both for nanoparticle production and in situ synchrotron studies; thus eliminating the need for transfer of in situ information to laboratory reactor designs.     

SQUID二阶磁梯度计标定系统的空间位置优化

超导量子干涉器件(SQUID)是利用磁通量子化与约瑟夫森效应这两种特性而形成的超导器件,可以分辨极微弱磁场变化,在磁信号灵敏探测方面应用广泛。因此,为确保其输出映射的准确性与使用质量,对使用过程中其进行定期校准至关重要。本文针对SQUID二阶磁梯度计在使用过程中的标定系统优化问题展开讨论,以标定线圈圆心为中心点建立笛卡尔坐标系,固定Y轴方向的相对位置,首先从Z轴方向移动标定线圈找到电流灵敏度最大位置范围,之后进一步精确标定位置,在X轴方向找到对Z轴方向移动最不敏感的相对位置,为标定中可能出现的人为误差提供更大的容错范围。并通过解析模型与有限元仿真模型相互验证,为后续实验提供了理论依据与先行性。利用解析模型与有限元模型及实测数据确定SQUID二阶磁梯度计在使用中的校准系数均为1.107,并对所提出的标定方法所产生的不确定度进行分析,为梯度计在低噪声环境条件下进行标定提供了更大的鲁棒性。     

Stroboscopic near-field imaging for the analysis of contraction of muscle cells

We have developed a stroboscopic near-field optical microscope for observation of biological specimens and observed glycerinated muscles before and after muscle contraction with the developed system. In the system, the optical field distribution localized near the specimen is recorded as the surface topographic distribution of a photosensitive film surface. Our system is very useful for observing living biological specimens with high resolutions, because it is possible to get stroboscopic image by using a photosensitive film as detecting optical distributions instead of a scanning of probes. We have succeeded in observing inner structures of muscle cells with sub-wavelength resolution and achieved higher contrast than an ordinary optical microscope.     

A conceptual project for a divertor monitor of the neutron yield in the ITER

The operating conditions of a neutron diagnostic system responsible for measuring the neutron yield in the ITER tokamak reactor are analyzed. Based on results of physical calculations and analysis of suitable methods for measuring the neutron yield, an original concept of a system for measuring neutron fluxed in the divertor zone of the ITER is proposed. The design for the neutron flux monitor located in the divertor zone of the tokamak is selected in view of the requirements specified for the neutron diagnostic system of the ITER and its operating conditions. Four fission chambers with different sensitivities and radiator materials are used as sensitive elements of the monitor. This system is capable of measuring neutron fluxes over the entire dynamic range of the neutron yield in the ITER with an error of ≤10% and a time resolution of 1 ms that are necessary for studying the physical mechanism of thermonuclear plasma ignition and burning. Several possible variants for housing the detector unit inside the divertor assembly and integrating it in the existing project are proposed. The problems of carrying out efficiency calibration of the divertor neutron monitor with the aim of determining the absolute value of the neutron yield in the ITER tokamak reactor are discussed.     

非流形曲面Loop细分研究

工业产品几何造型技术的发展要求，以及代数拓扑学复形等概念引入到几何造型中，因此产生了非流形几何造型理论。参数曲面造型所表示的物体复杂性受到限制，细分造型计算简单，可以表达任意拓扑关系，目前在图形学中已得到广泛研究并在三维建模、计算机动画中得到广泛应用。本文介绍了扩展实现Loop细分算法，使之能应用于非流形曲面，并相应提出了一种简易的基于三角形控制网格的数据结构。     

Steady state characteristics of a tilting pad journal bearing with controllable lubrication: Comparison between theoretical and experimental results

This paper is aimed at presenting results regarding the static and thermal behavior of a tilting-pad journal bearing operating under controllable regime. The bearing is rendered controllable by injecting high pressure oil into the clearance using holes drilled across the bearing pads in the radial direction. The modification of the injection pressure enables to modify the bearing static and dynamic properties according to the operational needs. The results presented are obtained using a theoretical model, which considers all the effects that determine the bearing behavior (controllable elastothermohydrodynamic lubrication regime), as well as using a test rig designed and built to this effect. The comparison between experimental and theoretical results provides solid ground to determine the accuracy of the available model for the the prediction of the steady-state behavior of the tilting-pad bearing with controllable lubrication. Among the parameters considered for the study are: oil film temperature field, resulting forces over rotor and pads, and rotor equilibrium position. The results obtained show good agreement between theory and experiment, as long as the assumptions on which the model is based are respected. Also, it is shown that some improvements are possible when it comes to model the steady-state behavior of the controllable bearing with the injection system turned off.     

Design and dynamic analysis of a pneumatic impulse generating device for the non-destructive testing of ground anchorages

This paper describes the design and dynamic analysis of an impulse-generating device which has been developed for use as part of a system to test ground anchorage systems non-destructively. The device is a relatively simple pneumatically operated design similar in function to a small air hammer working under computer control. An accelerometer attached to the device provides the measurement function. Results from the testing system are presented which show that in some cases the response of the anchorage to the input is a complex spectrum of frequencies. A dynamic model of the device, including the pneumatic system, is presented and results from this indicate that multiple impacts are occurring within the device during the measurement period. Analysis of the frequency spectrum of a two impulse force input is presented and using a single degree of freedom system and a previously developed and validated model of a ground anchorage, it is shown how the two impulses can produce the type of response exhibited by the test result from an anchorage. Some possible mechanical and signal processing solutions to mitigate the problem are presented.     

Pulsed differential reactors and their use for kinetic studies of gas-solid reactions-application to mechanistic studies of the reactions of hydrogen sulfide and the alkaline minerals in coal

An experimental system has been constructed and used to measure the rate of gas-solid reactions. The main advantages of the experimental technique are that it can be used to measure the individual rates of reactions when complex reactions occur simultaneously, and that it permits one to measure very accurately the isothermal rate of reaction of very exothermic or endothermic reactions. The components of the system are a microdifferential reactor, a gas chromatograph, and a pulse injector, all of which are available commercially. Pulses of reactive gas were injected periodically into the differential reactor and the pulses of gaseous reaction products were separated and analyzed by chromatographic techniques. The signal from the chromatograpgh was recorded and integrated. The injector and the integrator were synchronized so that completely automatic operation was possible. The system was used to measure the rate of reaction of hydrogen sulfide with the alkaline minerals which are present in coal, calcit, dolomite, and sidrite. Data are presented and the mathematical analysis of the data is described in detail.     

Modeling a multivariable reactor and on-line model predictive control

A nonlinear first principle model is developed for a laboratory-scaled multivariable chemical reactor rig in this paper and the on-line model predictive control (MPC) is implemented to the rig. The reactor has three variables-temperature, pH, and dissolved oxygen with nonlinear dynamics-and is therefore used as a pilot system for the biochemical industry. A nonlinear discrete-time model is derived for each of the three output variables and their model parameters are estimated from the real data using an adaptive optimization method. The developed model is used in a nonlinear MPC scheme. An accurate multistep-ahead prediction is obtained for MPC, where the extended Kalman filter is used to estimate system unknown states. The on-line control is implemented and a satisfactory tracking performance is achieved. The MPC is compared with three decentralized PID controllers and the advantage of the nonlinear MPC over the PID is clearly shown.     

Design and investigations of the superconducting magnet system for the multipurpose superconducting electron cyclotron resonance ion source

The production of intense beams of heavy ions with electron cyclotron resonance ion sources (ECRIS) is an important request at many accelerators. According to the ECR condition and considering semi-empirical scaling laws, it is essential to increase the microwave frequency together with the magnetic flux density of the ECRIS magnet system. A useful frequency of 28 GHz, therefore, requires magnetic flux densities above 2.2 T implying the use of superconducting magnets. A cooperation of European institutions initiated a project to build a multipurpose superconducting ECRIS (MS-ECRIS) in order to achieve an increase of the performances in the order of a factor of ten. After a first design of the superconducting magnet system for the MS-ECRIS, the respective cold testing of the built magnet system reveals a lack of mechanical performance due to the strong interaction of the magnetic field of the three solenoids with the sextupole field and the magnetization of the magnetic iron collar. Comprehensive structural analysis, magnetic field calculations, and calculations of the force pattern confirm thereafter these strong interactions, especially of the iron collar with the solenoidal fields. The investigations on the structural analysis as well as suggestions for a possible mechanical design solution are given.     

Moving EM: the Rapid Transfer System as a new tool for correlative light and electron microscopy and high throughput for high-pressure freezing

In this paper, the Rapid Transfer System (RTS), an attachment to the Leica EMPACT2 high‐pressure freezer, is described as a new tool for special applications within the cryofixation field. The RTS is an automated system that allows for fast processing of samples (<5 s) that make it possible for the first time to use high‐pressure freezing in combination with high time resolution correlative light and electron microscopy. In addition, with a working cycle of 30 s this rapid turn over time allows one to acquire more samples of biopsy material before it deteriorates than with other HPF machines with longer cycle times. With the use of the RTS it was possible to obtain three samples each of four different tissues in 6 min. Together with the finding that 90% of samples of cells grown on sapphire discs were well frozen, the RTS was both fast and reliable. Most important, together with other newly developed accessories, the RTS made it possible to capture specific events occurring live in the cell as observed by light microscopy, to cryofix that sample/event within 4 s, and then to analyze that event at high resolution in the electron microscope with excellent preservation of ultra‐structure. These developments should give us the tools to unravel intracellular processes that can be observed by live cell imaging but are too rare or fast to be picked up by routine EM methods or where the history of a structure is necessary to be able to discern its nature.     

干式空心电抗器匝间短路故障暂态特性仿真研究

从理论上分析了干式空心电抗器从正常运行状态到匝间短路故障状态下的匝间短路动态过程,建立了暂态电路耦合计算模型,并利用ANSYS Maxwell软件模拟了匝间短路故障的暂态特性,提出了通过安装在电抗器封装上的检测线圈实现对电抗器短路位置引起的磁场突然变化的检测方法。通过实验研究表明,采用本文提出的方法可以在较早的故障期间检测到匝间短路故障。