一种变温环境下水听器灵敏度校准系统的设计

针对缺少在变温条件下校准水听器灵敏度方法的问题,设计了一套基于动圈换能器声管的变温水听器灵敏度校准系统。建立模型分析声管内的声压分布,并计算了变温后对灵敏度校准结果的补偿量;利用Comsol仿真不同声管厚度对声场的影响,分析了底面非均匀振动和不同尺寸的水听器对校准结果的影响,确定了合适的声管尺寸和测量方法。分别在常温与变温条件下对不同尺寸的水听器进行校准并将校准结果与标准值比较。结果表明,此系统在常温下的校准结果与标准值的偏差低于0.5 dB,变温条件下的测量结果与标准值偏差低于0.6 dB,整体系统的扩展不确定度约为1.0 dB。     

Studies on a sealed-cell lambda-point device for use in low temperature thermometry

We report here the development of a sealed-cell lambda-point device which has been used to realize the lambda-point temperature of ⁴He, T_λ=2.1768 K, to a precision of 0.04 mK with simple automatic control. With this device, one can produce and maintain T_λ-plateaus for unlimited duration with no ascertained temperature drift. This unique performance is achieved by a design, which makes it possible to keep a HeI/HeII interface quasi-stationary inside a vertical variable-conductance capillary tube. The capillary connects a top HeII-cell and a bottom HeI-cell at its two ends, and acts as a sensitive heat switch which automatically adjusts a heat input to the bottom HeI-cell to compensate exactly the heat conducted out of the HeII-cell to the environment. The HeI/HeII interface thus stays at an equilibrium height determined by the magnitude of heat flow through the capillary and by the temperature difference along the capillary. The sharp difference between the thermal conductances of the interfacing HeII and HeI columns is the underlying physics of this self-adjusting function. Realization of T_λ is achieved after appropriate corrections to the thermometer reading at the HeII-cell, in particular, by extrapolating to zero heat flow through the device.     

Optimization of the underwater structures employed when calibrating hydrophones in a free field

The results of investigations of the distribution of sources of reflections on the bars employed to position hydrophones under water during free-field measurements are analyzed. It is established experimentally that the sources of reflections are formed on parts of the bars where its reflective power changes sharply. It is shown that structures, designed taking into account the mechanism of the distribution of sources of reflection, enable the interference distortions of the acoustic field to be reduced considerably. __________ Translated from Izmeritel’naya Tekhnika, No. 1, pp. 60–63, January, 2007.     

炭/碳化硅复合材料在高温燃气环境中的铰链传动与摩擦行为

采用化学气相渗透法(CVI)制备了二维炭纤维增强碳化硅(C/SiC)全陶瓷基复合材料铰链试样. 高温燃气风洞实现了铰链试样在1800℃高温氧化气氛中传动与摩擦行为的试验模拟. 基于耦合应力等效模拟系统的开发, 采用摩擦力矩的变化表征材料的传动与摩擦行为. 对比分析了材料在室温与高温下以传动为背景的高载荷、低转速摩擦磨损行为及机理. C/SiC复合材料铰链试样在高温燃气环境中稳定的摩擦力矩和对滑动时间的不敏感, 验证了材料在高温下更稳定、更可靠的高温摩擦性能及热承载能力. 高温下表面生成的氧化反应膜通过应力的重新分布起到有效的保护与润滑作用.     

Comprehensive Implementation of Standardization Work:the Project for Air Disinfection and a Conservation-oriented Sterile Environment in Hospitals

In China, the technical information currently available both domestically and abroad has been reviewed in an attempt to integrate the technique of ultraviolet air disinfection with Grade Ⅱ filters and develop a sterile conservation-oriented environment. As detection showed, such a sanitary system of air disinfection, integrated by ultraviolet air disinfection and Grade Ⅱ filters can reach the same standard of cleanliness as a high efficiency particle filter.This system easily satisfies the cleaning of air in hospital wards, surpassing the sterile air standards and the requirements of the National Bacteria Indicator (NBI). As a result of this system's efficiency, resources and running costs can be reduced dramatically. Therefore, revision of the national standards of Structural Technical Specification of the Cleaning Operation Department needs to move forward.     

海洋环境下钢材表面镀铝工艺的研究进展

钢材作为基础性结构材料被广泛应用于海洋工程领域,随着国家对海洋开发的支持力度不断加大,对应用于此环境下的钢材的需求也不断增加。但是,暴露于苛刻海洋环境下的钢材极易与周围的含氯、硫等介质发生反应而受到严重腐蚀,同时,潮汐、日照、溶解氧、微生物以及深海压力和热液带来的高温等环境条件也会加速钢材的腐蚀,严重影响海洋工程设施的服役安全、寿命以及可靠性。 因此,对钢材进行表面处理提高其耐腐蚀性能成为研究热点,其中涂层制备技术是最常用的腐蚀控制方法。铝及铝合金在腐蚀环境及高温氧化环境下表面可以形成一层致密的氧化膜,是一种常用的耐腐蚀涂层材料,通过不同工艺在钢材表面制备的铝涂层已达到了长效的防腐蚀效果。 目前,制备铝涂层的工艺主要有热浸镀法、电镀法、包埋渗铝法及热喷涂法等。热浸镀铝工艺因操作简单、成本低廉而被广泛应用于海洋平台、海洋码头、桥梁等海洋基础设施。电镀铝工艺制备的涂层厚度、组织、形貌可控,可以实现在微小零件上的精准沉积。新型绿色环保的离子液体体系的开发,在提高电镀效率和涂层质量的同时降低了对环境的污染。粉末包埋渗铝制备的涂层具有极高的抗高温氧化性能,被广泛应用于海洋油气开采工程。低温包埋渗铝工艺可避免传统渗铝工艺高温导致的钢材力学性能下降。此外,浆料渗铝以及气相渗铝等工艺的开发拓宽了渗铝工艺的应用领域。热喷涂工艺在海洋环境下应用最为广泛,所制备的铝涂层具有极高的耐腐蚀性能,其中火焰喷涂、电弧喷涂、冷喷涂等工艺能够实现新型防腐蚀铝涂层的设计与制备。 本文针对海洋环境下应用的钢材,详细介绍了在其表面镀铝工艺的研究进展,包括热浸镀、电镀、包埋渗铝和热喷涂等,并对不同镀铝工艺在海洋环境下的应用及发展方向做了展望。     

虚拟企业环境下人员组织方式及其实现条件

虚拟企业环境下更常见的人员的组织形式将是基于合同网的工作团队,它更加具有弹性和反应力。指出了虚拟企业环境下对人员组织方式的要求,分析了基于行政命令和长官意志的工作团队的局限性,探讨了基于合同网的工作团队的组织方式及其优点,提出了其实现的前提条件。     

Experimental and numerical investigation of catalytic PM combustion in a fluidized bed type PM removal device for low-temperature continuous regeneration

A fluidized bed filter can perform highly efficient PM collection and low-temperature continuous regeneration. However, to further reduce continuous regeneration temperature, a rough surface bed particle was selected herein. It is expected that the rough surface increases and stabilizes doped catalyst on bed particle even in fluidized bed. This bed particle can stably support 9.48 g-catalyst/kg-bed particle of doped catalyst versus 1.58 g-catalyst/kg-bed particle in previous research. This increase in catalyst amount increases the probability of good PM-catalyst contact, and collection efficiency can easily maintain its initial value due to catalytic PM combustion. PM combustion also depends on fluidization. Thus, combustion kinetics in a fluidized bed was investigated via a newly developed thermogravimetric analyzer that considered PM-gas relative velocity, and a constructed kinetic model was applied to numerical simulation. PM combustion obeyed an Arrhenius relationship, and the effect of PM-gas relative velocity was included in the kinetic model as a mass transfer term. A continuous regeneration experiment was conducted under optimal conditions, and the continuous regeneration temperature is 330 °C. As water vapor occurs in combustor exhaust, we added 10 vol% water vapor and found that the continuous regeneration is further reduced to 300 °C.     

浸没发热球体冷冻水绕流作用下水体温度稳定性分析

本文通过推导在冷冻水绕流发热球体传热过程中,水池内水体平均温度随时间的变化公式,研究冷冻水理论降温所需最小流量、水体稳定温度和所需稳定时间的主要影响因素,分析水池内所容纳水体质量及初始温度、冷冻水流量及温度等参数对水体温度稳定性的影响。根据某工程实际情况确定冷冻水温度、流量等参数,运用理论推导公式和CFD模拟技术计算水体温度稳定性。结果表明:当冷冻水温度为17℃时,理论最小质量流量为83. 7 t/h。经过6～7个月后水体温度将达到稳定,稳定温度为22. 4℃。     

朝鲜半岛构造系统地质环境演化及动力学机制的地球卫星遥感影像解译研究

采用将东亚地区综合资料分析成果与地球卫星遥感影像解译相结合的方法,深入研究了全球构造域中典型的构造地段朝鲜地块。详细识别出朝鲜半岛地区的基本构造形式,其基本类型主要有环形构造（及辐射构造）、追踪构造、共轭构造、菱形构造、多米诺构造等;对其构造地质环境演化过程及地球动力学机制进行了宏观阐述,晚古生代之前朝鲜半岛是由中国东部三个不同板块（华北板块;扬子板块、华南板块）贴拼焊接而成,中生代隆起成陆以后遭受了三期构造运动的影响（松林运动、大宝运动、佛国寺运动）,新生代发生了玉岭运动。朝鲜地块基本构造形式的形成受中国边缘海盆地与日本海盆地的侧向水平运动的影响,其构造主应力轨迹线方向为北东-南西向延伸,近代主应力轨迹线方向表现为北西西-南东东向展布,对其引起的现代地质作用及环境效应得到有关部门的充分注意。     

Absence of a Competition Between Magnetism and Superconductivity in Layered Nickel Borocarbides: Common Correlations of Tc with Crystal Chemical Parameters for Magnetic and Nonmagnetic Compounds

In the present work, an analysis of the crystal chemical parameters of nickel borocarbides RNi₂B₂C (R = rare earth) is given. The reasons for the dependence of superconducting transition temperature (T _c) on crystal chemical parameters by two separate curves for magnetic and nonmagnetic R are considered. For all R, a common pattern of dependence of T _c on crystal chemical parameters similar to that existing in layered quasi two-dimensional systems (HTSC cuprates and diborides) is established. The absence of the influence on the T _c of borocarbides of magnetic properties R is also established. On the basis of the correlations found, the radii of a number of rare earths are more precisely defined, and T _c of compounds at various substitutions R are calculated.     

Advances in piezoelectric thin films for acoustic biosensors,acoustofluidics and lab-on-chip applications

Recently, piezoelectric thin films including zinc oxide (ZnO) and aluminium nitride (AlN) have found a broad range of lab-on-chip applications such as biosensing, particle/cell concentrating, sorting/patterning, pumping, mixing, nebulisation and jetting. Integrated acoustic wave sensing/microfluidic devices have been fabricated by depositing these piezoelectric films onto a number of substrates such as silicon, ceramics, diamond, quartz, glass, and more recently also polymer, metallic foils and bendable glass/silicon for making flexible devices. Such thin film acoustic wave devices have great potential for implementing integrated, disposable, or bendable/flexible lab-on-a-chip devices into various sensing and actuating applications. This paper discusses the recent development in engineering high performance piezoelectric thin films, and highlights the critical issues such as film deposition, MEMS processing techniques, control of deposition/processing parametres, film texture, doping, dispersion effects, film stress, multilayer design, electrode materials/designs and substrate selections. Finally, advances in using thin film devices for lab-on-chip applications are summarised and future development trends are identified.