铠装贵金属热电偶测量端位置的确定方法

热电偶测量端位置的准确定位对于热电偶的校准和使用有着重要影响,特别对于铠装贵金属热电偶来说,由于无法通过肉眼准确识别保护管内部热电偶测量端的位置,因此在热电偶检定和使用过程中一般将其外保护管顶部作为测量端所在位置。然而通过现场试验发现,铠装贵金属热电偶测量端一般并不位于保护管顶部,本文提供了一种准确定位铠装贵金属热电偶测量端的方法。     

Experimental study on a simple Ranque-Hilsch vortex tube

The Ranque-Hilsch vortex tube is a device by which cold gas can be generated using compressed gas. To understand the cooling mechanism of this device, it is necessary to know the pressure, temperature, and velocity distributions inside the tube. In order to investigate this, a simple vortex tube is built and nitrogen is used as its working fluid. A special Pitot tube is used for the measurement of the pressure and velocity. This Pitot tube consists of a capillary which has only one hole in the cylinder wall. With this Pitot tube, the pressure and velocity fields inside the tube were measured. In the same way, the temperature field was measured with a thermocouple. The results of three different entrance conditions are compared here. With the measurements results, the analysis based on the two thermodynamic laws has been made. It is found that rounding off the entrance has influence on the performance of the vortex tube. The secondary circulation gas flow inside the vortex tube can be enhanced and enlarged, the performance of the Ranque-Hilsch vortex tube improved.     

A Capillary Tube Viscometer Designed for Measurements of Hydrogen Gas Viscosity at High Pressure and High Temperature

A capillary tube viscometer was developed to measure the dynamic viscosity of gases for high pressure and high temperature. The apparatus is simple and designed for safe-handling operation. The gas was supplied to the capillary tube from a high-pressure reservoir tank through a pressure regulator unit to maintain a steady state flow. The measurements of a pressure drop across the capillary tube with high accuracy under extreme conditions are the main challenge for this method. A differential pressure sensor for high pressures up to 100 MPa is not available commercially. Therefore, a pair of accurate absolute pressure transducers was used as a differential pressure sensor. Then the pressure drop was calculated by subtracting the outlet pressure from the inlet one with a resolution of 100 Pa at 100 MPa. The accuracy of the present measurement system is confirmed by measuring the viscosity of nitrogen as a reference gas. The apparatus provided viscosities of nitrogen from ambient temperature to 500 K and hydrogen from ambient temperature to 400 K and for pressures up to 100 MPa with a maximum deviation of 2.2 % compared with a correlation developed by the present authors and with REFPROP (NIST).     

Exchange Collisions, Wall Interactions, and Resettability of the Hydrogen Maser

Experiments were performed in order to verify the resettability of the hydrogen maser. The method consisted of measuring the output frequency of one maser against the hydrogen pressure. It was found that at a given tuning of the cavity no shift larger than 2.1 parts in 1013 was observed for a change of 4 to 1 in pressure. This experiment also showed that the pressure shift due to exchange collisions, predicted by Bender, could not be observed for the field-independent transition in the hydrogen maser. Two masers, having the same storage bulb design and the same wall coating, were tuned by this technique and were found to have a frequency difference of 7.6 parts in 1013. Experiments on the wall coating of the hydrogen maser storage bulb were made. Relaxation and decorrelation times of various materials were measured. The hyperfine splitting of the ground state of hydrogen measured against cesium is also given.     

介质阻挡放电常压氮气渗氮研究

利用介质阻挡放电进行常压氮气渗氮研究取得突破性进展，研究结果表明，介质阻挡放电常压氮气渗氮有可能成为一种有前途的环保型金属表面强化技术。     

New Approach in Filling of Fixed-Point Cells: Case Study of the Melting Point of Gallium

The typical way of constructing fixed-point cells is very well described in the literature. The crucible is loaded with shot, or any other shape of pure metal, inside an argon-filled glove box. Then, the crucible is carefully slid into a fused-silica tube that is closed at the top with an appropriate cap. After that, the cell is removed from the argon glove box and melted inside a furnace while under vacuum or filled with an inert gas like argon. Since the metal comes as shot, or in some other shape such as rods of various sizes, and takes more volume than the melted material, it is necessary to repeat the procedure until a sufficient amount of material is introduced into the crucible. With such a procedure, there is the possibility of introducing additional impurities into the pure metal with each cycle of melting the material and putting it back into the glove box to fill the cell. Our new approach includes the use of a special, so-called dry-box system, which is well known in chemistry. The atmosphere inside the dry box contains less than 20 ppm of water and less than 3 ppm of oxygen. Also, the size of the dry box allows it to contain a furnace for melting materials, not only for gallium but for higher-temperature materials as well. With such an approach, the cell and all its parts (pure metal, graphite, fused-silica tube, and cap) are constantly inside the controlled atmosphere, even while melting the material and filling the crucible. With such a method, the possibility of contaminating the cell during the filling process is minimized.     

超大规模集成电路硅片的内吸杂

介绍了吸杂的分类与效果以及内吸杂工艺，并综述了金属在硅中的性质，主要阐明了乳在内吸杂中的作用，简述了氮对吸杂的影响，并讨论了内吸杂的物理机理。最后探讨了今后吸杂的发展方向。     

Pressure build-up at the metal delivery tube orifice in ultrasonic gas atomization

The effects of geometry (diameter and tip design) and position (relative to the gas nozzles) of the metal delivery tube in an ultrasonic gas atomization (USGA) device on the pressure condition in the gas-metal interaction zone at the tube orifice have been studied. Simulation of ultrasonic gas (argon or nitrogen) atomization has been conducted, both at low (3.5 to 14 atm) and high (15 to 75 atm) atomization pressures. Low gas atomization pressures are generally used in spray deposition processes such as liquid dynamic compaction (LDC), while high pressures are used for powder production. Depending on the experimental conditions, i.e. the shape and angle of the taper at the metal delivery tube orifice or its position with respect to the nozzles' gas exit common plane, either partial vacuum (equivalent to downward aspiration of the melt) or overpressures (equivalent to back-pressurization of the melt) at the metal delivery tube was detected. Underpressure and overpressure effects were found to increase with gas atomization pressure. The maximum pressure differences measured with respect to the atomization chamber pressure were about 0.15 to 0.25 atm for the low-pressure experiments, and 0.50 to 0.60 atm for the high-pressure experiments. Underpressures or overpressures of these magnitudes have a large effect on the metal flow rate during gas atomization, either enhancing or reducing it, and thus changing significantly the gas to metal flow ratio. Because this is a crucial parameter for both the USGA and the LDC processes, the state of pressure at the delivery tube's orifice has to be monitored carefully, in order to ensure optimal processing conditions.     

Verbessertes Kaltkathoden‐Ionisationsmanometer mit verlängerter Lebensdauer

Improved cold‐cathode gauge with extended life‐time If a cold‐cathode gauge is operated in a hydrocarbonous gas atmosphere at high vacuum pressures, its mean life‐time is substantially limited by a contamination of the electrodes and thus by a strong change of the gauge characteristic. Consequently, the pressure reading of the gauge becomes erroneous. This paper presents an improved cold‐cathode gauge of the inverted magnetron‐type, which was specially designed and developed for the long‐term operation at high pressures or/and in gas atmospheres with high contents of hydrocarbons. It was realized by a special electrode geometry using two separate and independent discharge chambers in one common gauge housing. Whereas the discharge zone positioned directly at the tube entrance works only as ion baffle, the second discharge zone located more interior is used only as gauge for pressure measurement. Compared with conventional cold‐cathode gauges the new gauge has a significantly extended useful life‐time. The prototype of the inverted double‐magnetron gauge and test results on its long‐term measuring behavior are presented.     

Modeling and simulation of the transcritical CO2 heat pump system

In this study, a CO₂ transcritical cycle model without imposing any excessive constraints such as fixed discharge pressure and suction pressure is developed. The detailed geometrical variation of the gas cooler and the evaporator have been taken into account. The model is validated with the experimental measurements. Parametric influences on the CO₂ system with regard to the effect of dry bulb temperature, relative humidity, inlet water temperature, compressor speed, and the capillary tube length are reported. The COP increases with the dry bulb temperature or the inlet relative humidity of the evaporator. Despite the refrigerant mass flowrate may be increased with the inlet water temperature, the COP declines considerably with it. Increasing the compressor speed leads to a higher heating capacity and to a much lower COP. Unlike those of the conventional sub-critical refrigerant, the COP of the transcritical CO₂ cycle does not reveal a maximum value against the capillary tube length.     

On-line D/H analysis for water, natural gas, and organic solvents by manganese reduction

A new technique for on-line sample preparation and D/H determination is described. The technique is suitable for the preparation of fresh and brine waters, as well as natural gases and organic solvents. A 5-microL sample of water or hydrogen equivalent is injected and reduced by means of hot manganese metal in a specially designed reaction tube surrounded by a tube furnace and attached directly to the mass spectrometer inlet without modification.The hydrogen gas flows directly into the MS to be analyzed by reference/sample comparison. The reproducibility varied between 0.7 and 1.8% for all liquid and gas samples. The accuracy of this technique is confirmed by analysis of IAEA standard waters V-SMOW, GISP, and SLAP, as well as NGS-3 (IAEA methane intercomparison material).     

基于四负载方法的汽车发动机排气源特性研究

传统的四负载法由于特殊的求解方式,管外测量时环境带来的干扰极易造成求解不稳定,从而影响计算结果精度.采用改进传统的四负载方法,通过管内测量以及获取更精确的直管四端极子参数来提高计算结果精度.管内测量通过测取管内压力波动来提取管内声压值.精确的直管四端极子参数通过三维有限元方法获取.最后通过仿真获取直管末端辐射声压值,并与试验结果进行对比,在主要峰值处吻合良好.同时与传统四负载法仿真结果对比,表明所改进的四负载方法计算结果更准确.     

Electrode material transport and re-deposition in high-intensity arc discharge lamps

A two-dimensional model of sintered electrode activator (in particular, barium) transport in the arc discharge lamp tube volume has been developed, based on a numerical solution of the non-stationary diffusion equation. The dependence of the barium atom flow density at the electrode rod tip on fill gas pressure and electrode dimensions has been calculated. It has been found that the main mechanism of activator transport to the rod tip is evaporation from the sintered body and diffusion through the gas. Evolution of tungsten rod emission characteristics caused by deposition of the evaporated material on its surface has been studied experimentally.     

低温容器的研制

着重介绍了低温高压液氢容器和全包式预冷夹套低温容器的结构，容器分为三导：外容器是真空容器，夹套容器是预冷介质容器，内容器是低温介质容器。容器可用液氮预冷，大大节省预冷液氢，全包式的预冷夹套液氢容器，使预冷夹套发挥最大作用，其关键是使用了锥筒式支承，锥筒小端支承在内容器颈管上，大端支承在外容器上，在内容器上没有任何支耳和凸台，透用于带预冷夹套低温容器和多层绝热低温容器。     

新型紫光放电管的研制

新型紫光放电管是由N2 气和Cs组成的一个放电器件。本文叙述了这种紫光放电管的制备、放电特性和辐射光谱特性并对N2 在低于市电幅度条件下能够保持连续放电给出了较为明确的解释     

Monte Carlo simulation of the electron beam scattering under gas mixtures environment in an HPSEM at low energy

The effects of various gas environment used in high pressure SEM inside the specimen chamber were investigated using Monte Carlo simulation. In order to improve the signal to noise ratio for the electron detection, we suggest to use helium gas-based mixture. The Helium gas is well known to reduce the skirt effect due to its low elastic scattering cross-section. The addition of an ionizing gas such as hydrogen or nitrogen is proposed to increase the inelastic scattering cross section which is mainly responsible for the ionisation process taking place during the beam-gas interactions. For all the mixtures (except He-Argon), the main results show that the skirt is slightly modified with the increase of the pressure. For the BSE detection, the signal to noise can remain high and gives a good contrast in imaging. Moreover, the presence of an ionizing gas will favour the ionizing process which is very important in beam-based electron detection. In this case, an increase of the signal to noise ratio can be expected.     

Metal oxide nanoarchitectures for environmental sensing

Metal oxide materials are widely used for gas sensing. Capable of operating at elevated temperatures and in harsh environments, they are mechanically robust and relatively inexpensive and offer exquisite sensing capabilities, the performance of which is dependent upon the nanoscale morphology. In this paper we first review different routes for the fabrication of metal oxide nanoarchitectures useful to sensing applications, including mesoporous thin films, nanowires, and nanotubes. Two sensor test cases are then presented. The first case examines the use of highly uniform nanoporous Al2O3 for humidity sensing; we find that such materials can be successfully used as a wide-range humidity sensor. The second test case examines the use of TiO2 nanotubes for hydrogen sensing. Going from a nitrogen atmosphere to one containing 1000 ppm of hydrogen, at 290 degrees C, 22-nm-diameter titania nanotubes demonstrate a 10(4) change in measured resistance with no measurement hysteresis.     

In situ Raman analysis of gas formation in NiMH batteries

In this paper Raman spectrometry is introduced in the field of sealed battery research for in situ gas-phase analysis and for longterm measurements. For this purpose, a new method was successfully applied in order to model battery behavior without interfering with operation. It is shown that oxygen, hydrogen, and nitrogen are responsible for the pressure increase that occurs during overcharging. The relative contribution of the different gases depends on the current imposed on the battery as well as the operating temperature. Reproducible and stable signals could be obtained even under severe conditions such as high pressure and elevated temperature. Oxygen and hydrogen are produced in side reactions taking place during battery operation. However, as nitrogen is unlikely to be a reacting gas inside the battery, the change in its partial pressure can be attributed to electrode expansion and a change in the electrolyte volume.     

The structure of reactively sputtered metal carbide and metal silicide solar selective absorbers

Transition metal carbide and metal silicide films have recently been reported to produce excellent solar selective absorbers when deposited as interference layers onto metal substrates by d.c. reactive sputtering. These films, with a graded or multilayered profile, typically have solar absorptances greater than 0.90 and thermal emittances less than 0.05. In this paper we report the results of electron diffraction and electron microprobe studies on uniform titanium carbide and titanium silicide films produced by d.c. magnetron sputtering titanium in an atmosphere of argon plus methane or silane.The films were found to be rich in the non-metallic component and to consist of small particles of a metallic titanium carbide or silicide embedded in a porous matrix of carbon or silicon. The ratio of non-metal to metal increases with the reactive gas pressure in the sputter discharge, as does the film resistivity.Films which had been annealed in vacuum for sufficient time to change their optical properties showed no observable structural changes but it is inferred that the changes in optical properties are caused by a precipitation of carbon or silicon from the metallic particles into the matrix, causing the deposits to become more dielectric.     

Fabrication of Lotus‐type Porous Metals and their Physical Properties

Lotus‐type porous metals whose long cylindrical pores are aligned in one direction were fabricated by unidirectional solidification in a pressurized gas atmosphere. The pores are formed as a result of precipitation of supersaturated gas when liquid metal is solidified. The lotus‐type porous metals with homogeneous size and porosity of the evolved pores produced by a mould casting technique are limited to the metals with high thermal conductivity. On the other hand, the pores with inhomogeneous pore size and porosity are evolved for metals and alloys with low thermal conductivity such as stainless steel. In order to obtain uniform pore size and porosity, a new “continuous zone melting technique” was developed to fabricate long rod‐ and plate‐shape porous metals and alloys even with low thermal conductivity. Mechanical properties of tensile and compressive strength of lotus‐type porous metals and alloys are described together with internal friction, elasticity, thermal conductivity and sound absorption characteristics. All the physical properties exhibit significant anisotropy. Lotus‐type porous iron fabricated using a pressurized nitrogen gas instead of hydrogen exhibits superior strength.