液体流量标准装置变温系统设计

介绍了液体流量标准装置的特点、发展方向及主要技术要求;分析了温度变化情况及影响因素。对变温系统方案进行比较分析,选出了电加热及制冷机组的变温方案、水换热的恒温方案;设计了并联式复合结构的变温系统结构;总结了不同变温方案参数计算方法;运用实例对设计方案、方法进行了验证。

原位式准静态压电材料温度特性测试系统研发

压电材料的压电-温度特性会直接影响到压电器件的工作稳定性,是压电器件研发的重要依据。文中基于准静态测量方法研制上、下位机系统,实现了原位压电-温度特性测试。其次,设计开发了变温管式炉、激振器驱动、信号调理与采集电路,构建了准确的滤波与工频陷波算法。实测结果表明,所设计系统测试结果稳定,能够准确测量压电-温度特性并标定压电材料相变温度,可为压电器件设计提供重要的参考。

激光显微共聚焦拉曼光谱仪变温系统的设计与研制

针对常规激光显微共聚焦拉曼光谱仪无法满足物质变温,特别是低温测试需求的问题,设计了适用于拉曼光谱仪的高精度变温系统。该系统采用GM制冷机作为制冷源,利用高纯无氧铜作为导冷介质,通过将GM制冷机的冷量传导至样品台,并利用控温仪进行温度控制,可以实现待测样品10 K-402 K范围的温度变化控制,控温精度高于0.008 K。相比于常规的低温测试设备,该系统无需采用液氮、液氦进行制冷,大幅降低了设备的使用及维护费用。同时,使用激光显微共聚焦拉曼光谱仪搭载该系统,成功获得了Si、V_(2)O_(5)等材料的变温拉曼光谱,验证了激光显微共聚焦拉曼光谱仪变温系统设计的可靠性。

台式核磁共振仪变温探头系统的研制

变温探头系统是拓展低场强核磁共振仪应用领域的重要部件.半导体致冷片由于体积小,功耗低,控制方便,广泛应用于各种制冷场合.本研究利用半导体致冷组件研制的变温探头系统能实现-20℃～60℃范围变温,相比传统高场强核磁共振波谱仪变温探头系统,结构简单、性价比高.在NMI20-analyst台式核磁共振仪上应用3.5%的CuSO4水溶液对本变温系统进行了测试,实验效果能够体现出相应的规律,具有实用价值.最后对系统与实验结果进行了讨论,给出了改进方案.

ESR波谱仪变温装置的研制

随着电子自旋共振波谱技术的发展和应用,变温装置已成为必不可少的重要附件。本文介绍了ESR波谱仪变温装置的原理、结构、性能指标及使用该装置测试的部分图谱。

实现变温扫描的扫描探针显微镜的发展与应用

将实现微尺度温度测量的技术按其温度控制方式分为两类,即控制探针的温度和控制样品的温度,所对应的仪器为扫描热显微镜和各类可直接应用于普通扫描探针显微镜的变温样品台,分别介绍其结构、工作原理及应用情况,分析了这两类具有不同控温方式的仪器的区别,并进一步讨论了目前在扫描探针显微镜变温辅助设备中仍然存在的问题以及实现变温扫描的扫描探针显微镜的发展前景。

热塑性塑料微注射成型的关键技术

综述了微注射成型技术存在的问题和改进方法,探讨了微注射成型机的塑化、注射和计量等装置的结构性能改进,并提出了监测系统的改进方案。在比较微注射成型模具和常规注射成型模具基础上,介绍了微注射成型模具的特殊变模温控制方法、抽真空排气方法、模具材料选择及模芯微细加工方法。还探讨了特殊热塑性塑料材料的开发和微注射成型零件的检测和处理方法,并进一步分析了微流动特征下计算机模流分析软件适应性。

Structure of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glass

Bi2O3-ZnO-B2O3 system glass is a kind of lead-free low melting sealing glasses. The structure of Bi2O3-ZnO-B2O3 system low-melting sealing glass was investigated by DSC, FT-IR, XRD and SEM. The results show that with the increase of B2O3 content, the transition temperature Tg and softening temperature Tf of Bi2O3-ZnO-B2O3 system low-melting sealing glasses increase, which leads to the liquid phase precipitation temperature increasing and promotes the structure stability in the glass. With increasing the heat treatment temperature, a large number of liquid phases appear in samples and the sinter efficiency of the samples increases. The FT-IR spectra of the glasses show the presence of some bands that are assigned to vibrations of Bi--O bond from [BO3] pyramidal and [BiO6] octahedral units and B--O from [BO3] and [BO4] units. With the decrease of B203 content, the crystallization tendency of the glass increases. In glass samples Bl and B〉 crystallization starts at 460 ℃ and 540 ℃, respectively. Both of them precipitate Bi24B2O39 phases.

Genetic Optimization Algorithm of PID Decoupling Control for VAV Air-Conditioning System

Variable-air-volume (VAV) air-conditioning system is a multi-variable system and has multi coupling control loops. While all of the control loops are working together, they interfere and influence each other. A multivariable decoupling PID controller is designed for VAV air-conditioning system. Diagonal matrix decoupling method is employed to eliminate the coupling between the loop of supply air temperature and that of thermal-space air temperature. The PID controller parameters are optimized by means of an improved genetic algorithm in floating point representations to obtain better performance. The population in the improved genetic algorithm mutates before crossover, which is helpful for the convergence. Additionally the micro mutation algorithm is proposed and applied to improve the convergence during the later evolution. To search the best parameters, the optimized parameters ranges should be amplified 10 times the initial ideal parameters. The simulation and experiment results show that the decoupling control system is effective and feasible. The method can overcome the strong coupling feature of the system and has shorter governing time and less over-shoot than non-optimization PID control.

Sensitivity of the Terrestrial Ecosystem to Precipitation and Temperature Variability over China

In this study, the sensitivities of net primary production(NPP), soil carbon, and vegetation carbon to precipitation and temperature variability over China are discussed using the state-of-the-art Lund-Potsdam-Jena dynamic global vegetation model(LPJ DGVM). The impacts of the sensitivities to precipitation variability and temperature variability on NPP, soil carbon, and vegetation carbon are discussed. It is shown that increasing precipitation variability, representing the frequency of extreme precipitation events, leads to losses in NPP, soil carbon, and vegetation carbon over most of China, especially in North and Northeast China where the dominant plant functional types(i.e., those with the largest simulated areal cover) are grass and boreal needle-leaved forest. The responses of NPP, soil carbon, and vegetation carbon to decreasing precipitation variability are opposite to the responses to increasing precipitation variability. The variations in NPP, soil carbon, and vegetation carbon in response to increasing and decreasing precipitation variability show a nonlinear asymmetry. Increasing precipitation variability results in notable interannual variation of NPP. The sensitivities of NPP, soil carbon, and vegetation carbon to temperature variability, whether negative or positive, meaning frequent hot and cold days, are slight. The present study suggests, based on the LPJ model, that precipitation variability has a more severe impact than temperature variability on NPP, soil carbon, and vegetation carbon.

FEATURES AND COMPARISONS OF THE QUASI-BIENNIAL VARIATIONS IN THE ASIA-PACIFIC MONSOON SUBSYSTEMS

The National Centers for Environmental Prediction (NCEP) reanalysis data, Climate Diagnostics Center Merged Analysis of Precipitation (CMAP) results, and NOAA Extended Reconstructed Sea Surface Temperature (SST), have been utilized in this paper to study the quasi-biennial variations in Asia-Pacific monsoon subsystems and associated SST anomalies (SSTA) and wind anomalies. Four monsoon indices are computed from NCEP/ National Center for Atmospheric Research (NCAR) reanalysis to represent the South Asian monsoon (SAM), South China Sea summer monsoon (SCSSM), Western North Pacific monsoon (WNPM) and East Asian monsoon (EAM), respectively. The quasi-biennial periods are very significant in Asia-Pacific monsoons (as discovered by power spectrum analysis), and for SAM and EAM---with moderate effects by El Ni?o-Southern Oscillation (ENSO)---the quasi-biennial periods are the most important factor. For SCSSM and WNPM (once again due to the effects of ENSO), the quasi-biennial periods are of secondary durations. There are obvious interdecadal variations in the quasi-biennial modes of the Asia-Pacific monsoon, so in the negative phase the biennial modes will not be significant or outstanding. The wind anomalies and SSTA associated with the biennial modes are very different in the SAM, WNPM and EAM regions. Since the WNPM and SCSSM are very similar in the biennial modes, they can be combined into one subsystem, called SCS/WNPM.

Experimental study on the variation law of coal temperature during excavation in coal mines

By testing the temperature of the coal and the stress of the working surface, we got the variation law of coal temperature and coal stress during the excavation. The result shows that the activities of mining affect the coal temperature, the fluctuation of coal temperature and the coal stress is synchronous. During the smooth change of crustal stress, the coal temperature basically keeps unchanged, when the dynamic phenomenon appears, the coal temperature changes, as well the coal stress. Therefore, we can use the online coal temperature monitoring system to test the coal temperature of the working surface continuously, and it can provide basic information for forecasting coal mine power disaster before it happens.

Response of N_2O Emissions of Farmland Ecosystem on Temperature Rising

[Objective] The aim was to study on response of N2O emissions of farm- land ecosystem on temperature rising. [Methed] In farmland ecosystem in Huaibei City in Anhui Province, N2O emission by twelve varieties of crop on temperature was researched with DeNitrification-DeComposition （NDC）. [Result] Response of dry- land crop on temperature rising can be divided into three categories, as follows： The first category, N2O emission of crop changed little during the temperature increasing, for example, from 0 to 3 %;, the emissions by potatoes, cotton, maize and rapeseed increased little and decreased little when temperature changed from 1.5 to 3 ℃. Crops of the second category declined with temperature increasing in N2O emission, for example, N2O emission decreased by 8.1% with temperature increasing from 0 to 3 ℃, including sugar cane, tobacco, wheat, soybean and pea. In third category, N2O emission of crop grew with temperature increasing, for example, the emission of rice, vegetables and fruit trees increased by 22.8% when the temperature grew from 0 to 3 ℃. [Conclusion] The research indicated that N2O emission in ecosystem of drv farmland increased little with temoerature risina.

Counteracting the Effects of Sea Level Rise in Southeast Florida

Over the past 100 years, worldwide surface temperatures have increased at an unprecedented rate, contributing to warming of the oceans, melting ice fields and glaciers, and other adverse climatic effects. Southeast Florida＇s vulnerability derives from its geographic location, low elevation, porous geology, unusual ground and surface water hydrology, subtropical weather patterns, and proximity to the Atlantic Ocean. The region is especially susceptible to sea level rise. After several millennia of stable sea levels prior to the 20th century, sea levels have been rising at accelerating rates due to thermal expansion of the oceans and from land-based ice melt The Everglades ecosystem and the water supplies for southeast Florida are particularly vulnerable as neither can be protected without significant expenditures of public dollars, and even these efforts may not prove to be successful. New approaches may be required to improve the resilience and prolong the sustainability of the region＇s water resources and ecosystem. The efforts to adapt to sea level changes in both the urban area and ecosystem as outlined herein are date and incident based-climate changes may occur earlier or later so instead of spending limited public dollars early, expenditures can be adjusted given future information.

Energy analyses for the energetically self-sufficient supercritical water oxidation process

One of the bottle-neck problems to the commercial development of supercritlcal water oxidation （SCWO） is high operation cost. In this study the condition to realize an energetically self-sufficient SCWO process is analyzed. The reaction heat is recovered by means of Organic Rankine Circle. The process of SCWO for phenol is simulated with the Aspen Plus~ process simulator, and the results show that the influence of temperature on reaction heat is small at a constant pressure. It is reasonable to neglect the effect of temperature and to estimate the heat of reaction with average temperature when the temperature changes in a small range. The necessary condition to realize an energetically self-sufficient SCWO process is that the released energy is not less than consumed one. Whether a waste system with given chemical composition is energeticallyself-sufficient can be estimated by ^QR^QH 〉 W The thermodynamics analysis shows that energetically self-sufficient SCWO process with an Organic Rankine Cycle is a feasible technology for the recovery of SCWO reaction heat,and the energy balance point for phenol is 2wt%.

Thermal contact conductance estimation and experimental validation in hot stamping process

The variation in temperature of the blank would make major contribution to the mechanical properties of final component in hot stamping of ultra high strength steel(UHSS).It is important to use accurate thermal contact conductance(TCC) to carry out finite element simulation of hot stamping for reliable caculation results.In this paper,a flat compression test was performanced on a servo press.A fast response temperature measurement and data acquisition system was designed to obtain the temperature history of blank and die under different pressures.The thermal contact conductance between blank and die was got using an optimization algorithm.The error between the temperature curves using calculated thermal contact conductance and the curves of measurement temperature was analyzed.Result shows that reliable simulation results of temperature can be got through accurate thermal contact conductance.

Study of Optical Fibers Strain-Temperature Sensitivities Using Hybrid Brillouin-Rayleigh System

In this paper, the most recent progress as well as challenges of distributed optical fiber sensing （DOFS） in industrial applications is discussed. Compared to the vast market of sensors used to measure strain or temperature, the success of distributed optical fiber sensing （DOFS） at the industrial level is very limited, at best. One of the reasons for this lack of the wider acceptance is the mismatch between the commercially available systems and actual industrial requirements, especially for the spatial resolution and precision. These requirements are organized and clarified in the paper. It also describes the hybrid Brillouin-Rayleigh system, which exhibits capabilities surpassing those of strain gauges. The principles of the system are illustrated considering the fiber calibration methodology. Formulas required for determining strain, temperature, and hydro-pressure are derived and discussed. Finally, the examples of applications are presented.

Energy conversion characteristics of reciprocating piston quasi- isothermal compression systems using water sprays

Air compressors are vital and have numerous industrial applications. Approximately 8% of the annual operating electricity consumption in industrial countries is constituted by due to the use of air compressors. Because the poor heat transfer to the environment in the rapid compression process, the compression is non-isothermal, the efficiency of compressors is restricted. To improve their efficiency and achieve isothermal compression, this study proposes energy conversion reciprocating piston quasiisothermal compression using a water spray. First, a mathematical model of a reciprocating piston compressor with water sprays was established. Through experimental investigation and simulations, the mathematical model was validated. The energy conversion characteristics of the reciprocating piston compressor were then studied. To reduce compression power and enhance compression efficiency, it was first discovered that the critical parameters were the input pressure of the driving chamber, water spray mass, and compression volume ratio, which were then evaluated thoroughly. The higher the inlet pressure of the driving chamber, the faster the air compression velocity. Additionally, the compression efficiency was elevated as the water spray mass was gradually increased for a given compression volume ratio. When the compression volume ratio was increased from 2 to 3,the compression power increased from 172.7 J/stroke to 294.2 J/stroke and the compression efficiency was enhanced from 37.3%(adiabatic) to 80.6%. This research and its performance analysis can be referred to during the parameter design optimisation of reciprocating piston quasi-isothermal compression systems using water sprays.

Pyrochemical treatment of spent nitride fuels for MA transmutation

Nitride fuels have several advantages including high thermal conductivity and high metal density(like metallic fuels) and high melting point and isotropic crystal structure(like oxide fuels). Since the late 1990 s, the partitioning and transmutation of minor actinides(MA) has been studied to decrease the long-term radio-toxicity of high-level waste and to mitigate the burden of final disposal. Japan Atomic Energy Agency(JAEA) has proposed a dedicated transmutation cycle using an accelerator-driven system(ADS) with nitride fuels containing MA. The nitride fuel cycle we have developed includes a pyrochemical process. Our focus is on the electrolysis of nitride fuels and their refabrication from the recovered actinides; other processes are similar to the technology for metal fuel treatment and have been studied elsewhere. Here, we summarize our activity on the development of the pyrochemical treatment of spent nitride fuels.

Implementation of Interrogation Systems for Fiber Bragg Grating Sensors

The development of two simple methods for wavelength-optical intensity modulation techniques for fiber Bragg grating （FBG） sensors is presented. The performance is evaluated by measuring the strain and temperature. The first method consists of a narrow band source, an optical circulator, an FBG; and a power meter. The source and Bragg reflected signal from the FBG need to be matched to get linear results with good power levels. The source spectral power levels are very critical in this study. The power reflected from a matched reference FBG is fed into the measuring FBG in the second method. Since the FBGs are matched, the entire power is reflected back initially. During the measurement, the change in the measurand causes the reflected power from the sensing FBG to vary. A costly high resolution spectrum analyzer is required only during the characterization of the FBG and source. The performances of two interrogators are compared by measuring the strain and temperature. In the second method, the strain measurements can be made insensitive to the temperature variation by selecting a source with a flat spectrum at the measurement range. Highlights of these methods are the portability, cost effectiveness and better resolution.