In situ pressure calibration for piston cylinder cells via ruby fluorescence with fiber optics

A fiber-optic measurement technique is developed for estimating the pressure inside a piston cylinder cell up to approximately 4 GPa, based on the pressure-induced R1 fluorescence line shift of ruby (ruby scale). Ruby scale and a conventional technique (calibration on phase transitions of bismuth) were simultaneously applied to the cell filled with a pressure transmitting medium of isopropyl alcohol. The pressure readings of the two methods were consistent with each other, and no pressure gradient was observed. The ruby scale has the advantages of real time estimation and easy installation in a small space. Because of these advantages, three fibers were simultaneously introduced in the sample space at the same time, and pressure distribution was measured for Fluorinert (FC70:FC77=1:1), Daphne oil 7373, and Fomblin oil (YHVAC 13014).     

Efficiency measurement and uncertainty discussion of an electric engine powered by a "self-breathing" and "self-humidified" proton exchange membrane fuel cell

The efficiency of an automotive engine based on a "self-breathing" and "self-humidified" proton exchange membrane fuel cell stack (PEM FC) connected to a dc brushless electrical motor was measured under variable power load conditions. Experiments have been carried out on a small scale 150 W engine model. After determining the fuel cell static polarization curve and the time response to power steps, the system was driven to copy on the test bench a "standard urban load cycle" and its instantaneous efficiencies were measured at an acquisition rate of 5 Hz. The integral system efficiency over the entire urban load cycle, comprising the losses of the unavoidable auxiliary components of the engine, was then calculated. The fuel cell stack was operated mainly in "partial" dead-end mode, with a periodic anode flow channel purging, and one test was carried out in "pure" dead-end mode, with no anode channel purging. An uncertainty analysis of the efficiencies was carried out, taking into account either type A and type B evaluation methods, strengthening the discussion about the outcomes obtained for a system based on this novel simplified FC type. For our small scale engine we measured over the standard urban cycle, on the basis of the H(2) high heating value (HHV), a tank-to-wheel integral efficiency of (18.2+/-0.8)%, when the fuel cell was operated with periodic flow channel purging, and of (21.5+/-1.3)% in complete dead-end operation mode.     

Adaptation of the Bridgman anvil cell to liquid pressure mediums

The advantage of Bridgman anvil pressure cells is their wide pressure range and the large number of wires which can be introduced into the pressure chamber. In these pressure cells, soft solid pressure mediums such as steatite are used. We have succeeded in adapting the Bridgman cell to liquid pressure mediums. With this breakthrough, it is now possible to measure in very good hydrostatic pressure conditions up to 7 GPa, which is about twice the pressure attainable in piston-cylinder cells. The pressure gradient in the cell, estimated from the superconducting transition width of lead, is reduced by a factor of 5 in the liquid medium with respect to steatite. By using nonmagnetic materials for the anvils and the clamp and due to the small dimensions of the latter, our device is specially suitable for magnetotransport measurements in dilution fridges. This pressure cell has been developed to measure very fragile and brittle samples such as organic conductors. Resistivity measurements of (TMTTF)(2)BF(4) performed in a solid and a liquid pressure medium demonstrate the necessity of hydrostatic pressure conditions for the study of organic conductors at high pressures.     

Plastic bulging of sheet metals at high strain rates

The biaxial bulge test is a material test for sheet metals to evaluate formability and determine the flow stress diagram. Due to the biaxial state of stress induced in this test, the maximum achievable strain before fracture is much larger than in the uniaxial tensile test. A new dynamic bulge testing technique is simulated and analyzed in this study which can be performed on a conventional split Hopkinson pressure bar (SHPB) system to evaluate the strain-rate dependent strength of material at high impact velocities. Polyurethane rubber as pressure carrying medium is used to bulge the OFHC copper sheet. The use of hyperelastic rubber instead of fluid as a pressure medium makes the bulge test simple and easy to perform. The input bar of SHPB is used to apply and measure the bulging pressure. The finite element simulation using ABAQUS/explicit and analytical analysis are compared and show good correlation with each other. The results clearly show that as the strain-rate increases, the strength of the OFHC copper increases. From the study, a robust method to determine the material behavior under dynamically biaxial deformation conditions has been developed.     

The renewed airflow standard system in Japan for 5–1000 m3/h

The airflow standard system in Japan for the middle range (5–1000 m³/h) has been renewed since 2002. The constant volume tank to realize the standard was replaced to have better performance at higher pressure, although its principle is exactly the same as its predecessor. Otherwise, most hardware for the system is unchanged, however the software for controling the measurements is improved to give the capability for tele-calibration on a unique basis. The facility also has a unique time measurement system based on analog-to-digital (A/D) conversion to analyze instantaneous behaviors of flowmeters. This paper describes the outline of the renewed standard system together with some results from inter-laboratory comparison tests, in which very good consistency of the renewed system with other facilities, including its own predecessor, are shown.     

High-resolution thermal expansion measurements under helium-gas pressure

We report on the realization of a capacitive dilatometer, designed for high-resolution measurements of length changes of a material for temperatures 1.4 K ≤ T ≤ 300 K and hydrostatic pressure P ≤ 250 MPa. Helium ((4)He) is used as a pressure-transmitting medium, ensuring hydrostatic-pressure conditions. Special emphasis has been given to guarantee, to a good approximation, constant-pressure conditions during temperature sweeps. The performance of the dilatometer is demonstrated by measurements of the coefficient of thermal expansion at pressures P ? 0.1 MPa (ambient pressure) and 104 MPa on a single crystal of azurite, Cu(3)(CO(3))(2)(OH)(2), a quasi-one-dimensional spin S = 1/2 Heisenberg antiferromagnet. The results indicate a strong effect of pressure on the magnetic interactions in this system.     

Pressure jump relaxation setup with IR detection and millisecond time resolution

An instrument is described that allows the use of Fourier transform infrared (FTIR) spectroscopy as a detection system for kinetic processes after a pressure jump of up to 100 bars. The pressure is generated using a high performance liquid chromatography (HPLC) pump and water as a pressure transducing medium. A flexible membrane separates the liquid sample in the IR cell from the pressure transducing medium. Two electromagnetic switching valves in the setup enable pressure jumps with a decay time of 4 ms. The FTIR spectrometer is configured to measure time resolved spectra in the millisecond time regime using the rapid scan mode. All components are computer controlled. For a demonstration of the capability of the method first results on the kinetics of a phase transition between two lamellar phases of an aqueous phospholipid dispersion are presented. This combination of FTIR spectroscopy with the pressure jump relaxation technique can also be used for other systems which display cooperative transitions with concomitant volume changes.     

A typical noiseless Pockels E field sensor

A new practical Pockels E field sensor has been demonstrated. By combining a ferroelectric liquid crystal and a polarization-maintaining optical fiber with the sensor, it is theoretically found that almost all of the optical and electronic noise produced in the system can be completely eliminated. This fact has been experimentally proven not only under the conditions of a uniform electric field but also those of a nonuniform electric field and with ac voltages applied to a stabilized corona discharge. It is shown that if with the new Pockels E field sensor, the smallest detectable phase change was set to be 10(-5) rad, the minimum measurable E field in the electrical discharge could be reduced from 10(2) to 10(-1) kV/m. This technique should be useful not only for the field of electrical discharge studies but also for other optical measurement applications such as length, temperature, and pressure using appropriately configured transducers.     

Power quality impacts of high-penetration electric vehicle stations and renewable energy-based generators on power distribution systems

High-penetration renewable energy-based generators (REGs) in distribution systems have increased the importance of impact assessment involving these systems. This assessment focuses on power quality (PQ) and compatibility between REGs and existing system components. Electric vehicle (EV) technology has also recently achieved a substantial market share. This technology requires the development of charging stations similar to current petroleum fuelling stations in the near future. Thus, the effect of EV stations (EVSs) on PQ must also be considered. This study presents a PQ analysis on the effects of high-penetration EVS and REG systems, including wind turbines, grid-connected photovoltaics (PVs), and fuel cell (FC) power generation units on a modified 16-bus distribution system under different loading and weather conditions. All data on EVS, wind farm, PV, and FC units as well as weather conditions presented in this paper were collected from different power companies and the Malaysian Meteorological Department. The system is modelled and simulated using the MATLAB/Simulink software to study the effects of these technologies on system performances at various penetration levels. Simulation results indicated that the presence of high-penetration EVSs and REGs can cause severe PQ problems such as frequency and voltage fluctuations, voltage drop, harmonic distortion and power factor reduction.     

Evaluation of high temperature pressure sensors

It is becoming more important to measure the pressure in high temperature environments in many industrial fields. However, there is no appropriate evaluation system and compensation method for high temperature pressure sensors since most pressure standards have been established at room temperature. In order to evaluate the high temperature pressure sensors used in harsh environments, such as high temperatures above 250 °C, a specialized system has been constructed and evaluated in this study. The pressure standard established at room temperature is connected to a high temperature pressure sensor through a chiller. The sensor can be evaluated in conditions of changing standard pressures at constant temperatures and of changing temperatures at constant pressures. According to the evaluation conditions, two compensation methods are proposed to eliminate deviation due to sensitivity changes and nonlinear behaviors except thermal hysteresis.     

用于气动伺服系统的自适应神经模糊控制器

研究了一种基于压力比例阀的气动伺服系统自适应神经模糊控制器。其中的神经网络辨识器（NNI）通过高线训练可以充分逼近非线性动态系统的模型,并能够在线调整模糊控制器的控制规则。系统的位置控制精度和伺服特性有了很大改善。试验结果表明,所提出的控制器对该气动伺服系统具有很好的控制特性以及很强的自适应能力。     

FABRICATION OF AUTOMATIC ELECTROLYTE FILLING MACHINE FOR DYE-SENSITIZED SOLAR CELLS

An electrolyte filling machine, capable of filling liquid electrolyte (including viscous ionic liquid) into an enclosed cell with a single hole, has been developed. This system utilizes a vacuum-aided filling technique and has four major steps in the filling process, namely evacuation, discharging, filling, and returning extra electrolyte. The electrolyte is not open to ambient conditions throughout the filling process, and the return step minimizes the waste of electrolyte. This technique allows air bubble–free filling, better insertion of electrolyte into the mesoporous titanium oxide layer of dye-sensitized solar cells (DSC), and filling time is 40 s with a nonvolatile liquid-based electrolyte. Large area DSC modules that are 15 × 15 cm in size were tested using this machine, and conversion efficiency of 7.4% was obtained under the standard air mass (AM) 1.5 simulated sunlight.     

Uniform stress conditions in the diamond anvil cell at 200 kilobars

Pressure gradients in a diamond anvil cell have been measured with a 4:1 methanol:ethanol mixture as a pressure medium up to 350 kilobars. When pressure is applied rapidly, stress gradients are shown to be negligible up to 200 kilobars and probably above. With this procedure it is possible to significantly increase the precision of pressure measurements above 100 kilobars.     

Measurements of volatile organic compounds in the earth's atmosphere using proton-transfer-reaction mass spectrometry

Proton-transfer-reaction mass spectrometry (PTR-MS) allows real-time measurements of volatile organic compounds (VOCs) in air with a high sensitivity and a fast time response. The use of PTR-MS in atmospheric research has expanded rapidly in recent years, and much has been learned about the instrument response and specificity of the technique in the analysis of air from different regions of the atmosphere. This paper aims to review the progress that has been made. The theory of operation is described and allows the response of the instrument to be described for different operating conditions. More accurate determinations of the instrument response involve calibrations using standard mixtures, and some results are shown. Much has been learned about the specificity of PTR-MS from inter-comparison studies as well the coupling of PTR-MS with a gas chromatographic interface. The literature on this issue is reviewed and summarized for many VOCs of atmospheric interest. Some highlights of airborne measurements by PTR-MS are presented, including the results obtained in fresh and aged forest-fire and urban plumes. Finally, the recent work that is focused on improving the technique is discussed.     

Imaging cellular responses to mechanical stimuli within three-dimensional tissue constructs

The cellular response to environmental cues is complex, involving both structural and functional changes within the cell. Our understanding of this response is facilitated by microscopy techniques, but has been limited by our ability to image cell structure and function deep in highly-scattering tissues or 3D constructs. A novel multimodal microscopy technique that combines coherent and incoherent imaging for simultaneous visualization of structural and functional properties of cells and engineered tissues is demonstrated. This microscopic technique allows for the simultaneous acquisition of optical coherence microscopy and multiphoton microscopy data with particular emphasis for applications in cell biology and tissue engineering. The capability of this technique is shown using representative 3D cell and tissue engineering cultures consisting of primary fibroblasts from transgenic green fluorescent protein (GFP) mice and GFP-vinculin transfected fibroblasts. Imaging is performed following static and dynamic mechanically-stimulating culture conditions. The microscopy technique presented here reveals unique complementary data on the structure and function of cells and their adhesions and interactions with the surrounding microenvironment.     

山茱萸与熟地配伍时山茱萸中主要组分变化规律研究

为了研究山茱萸与熟地两种药物不同比例配伍时山茱萸中主要组分的变化规律,利用高效液相色谱（HPLC）法和电喷雾质谱（ESI-MS）法比较山茱萸和熟地药材单煎液、合煎液和单煎合并液中山茱萸主要组分的含量变化和各溶液的谱学行为。在一定质量比例内（m（山茱萸）∶m（熟地）≤4∶8）,山茱萸与熟地共煎有相互协同溶出的效应。合煎液中山茱萸莫诺苷、马钱苷和没食子酸组分的百分含量随熟地配伍比例的增加均呈现线性变化规律。不同的配伍方式（合煎与单煎合并）会产生不同的新物质。结果表明,熟地组分的存在对山茱萸组分的溶出有较大影响,但该影响不受温度的限制。     

Technique for anisotropic extension of organic crystals: application to temperature dependence of electrical resistance

We have developed a technique for the anisotropic extension of fragile molecular crystals. The pressure medium and the instrument, which extends the pressure medium, are both made from epoxy resin. Since the thermal contraction of our instrument is identical to that of the pressure medium, the strain applied to the pressure medium has no temperature dependence down to 2 K. Therefore, the degree of extension applied to the single crystal at low temperatures is uniquely determined from the degree of extension in the pressure medium and thermal contractions of the epoxy resin and the single crystal at ambient pressure. Using this novel instrument, we have measured the temperature dependence of the electrical resistance of metallic, superconducting, and insulating materials. The experimental results are discussed from the viewpoint of the extension (compression) of the lattice constants along the parallel (perpendicular) direction.     

Effective activation energies of chemical reactions and viscous flow of liquids depending on pressure in tribosystems with boundary and mixed friction

This work presents a kinetic analysis of the probable chemical reactions in a frictional contact zone depending on their energetics, temperature, and pressure, as well as the impact of these factors on the viscous flow of liquids, which can be used as an oily base in tribosystems with mixed boundary friction. The dependences of the effective activation energy and viscous flow of liquids on pressure have been analyzed. It has generally been shown that the effective activation energy of thermally activated chemical reactions and viscous flow depends on the activation volume and consists of standard activation energy under standard conditions and additional components connected with the influence of pressure on these processes.     

Application of simple adaptive control to water hydraulic servo cylinder system

Although conventional model reference adaptive control (MRAC) achieves good tracking performance for cylinder control, the controller structure is much more complicated and has less robustness to disturbance in real applications. This paper discusses the use of simple adaptive control (SAC) for positioning a water hydraulic servo cylinder system. Compared with MRAC, SAC has a simpler and lower order structure, i.e., higher feasibility. The control performance of SAC is examined and evaluated on a water hydraulic servo cylinder system. With the recent increased concerns over global environmental problems, the water hydraulic technique using pure tap water as a pressure medium has become a new drive source comparable to electric, oil hydraulic, and pneumatic drive systems. This technique is also preferred because of its high power density, high safety against fire hazards in production plants, and easy availability. However, the main problems for precise control in a water hydraulic system are steady state errors and overshoot due to its large friction torque and considerable leakage flow. MRAC has been already applied to compensate for these effects, and better control performances have been obtained. However, there have been no reports on the application of SAC for water hydraulics. To make clear the merits of SAC, the tracking control performance and robustness are discussed based on experimental results. SAC is confirmed to give better tracking performance compared with PI control, and a control precision comparable to MRAC (within 10 μm of the reference position) and higher robustness to parameter change, despite the simple controller. The research results ensure a wider application of simple adaptive control in real mechanical systems.     

Development and performance characterization of low, medium and high vacuum primary standards

Three primary vacuum standard systems having the highest metrological qualities in which the pressure is deduced directly from the involved physical quantities uniquely with the proper accuracy and precision, fine resolution and reliability have been developed. This vacuum standardization comprises of a Standard Mercury Manometer for low vacuum, a 4-stage Static Expansion Standard for medium vacuum and an orifice flow type Dynamic Expansion Standard for high vacuum. Each system has explicitly been established and precise measurement model equations with multiple variables are given. The performance of these standards has also been checked discretely with internationally recommended and reliably calibrated secondary standards along with the evaluation of different uncertainties that were found to be within the limits.