Camphor sulfonic acid (CSA) doped polypyrrole (PPy) films: Measurement of microstructural and optoelectronic properties

In this paper, camphor sulfonic acid doped polypyrrole have been successfully prepared using different weight percentages of camphor sulfonic acid (10–50%) dispersed in polypyrrole by solid state synthesis method. Films of CSA doped PPy were prepared by spin coating technique on a glass substrate. The effect of varying concentrations of CSA on the structure, morphology, optical and electrical properties of polypyrrole was explored using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) atomic force microscopy (AFM), UV–visible spectroscopy and two probe technique respectively. The presence of CSA in PPy matrix and their interaction was confirmed by using XRD and FTIR techniques. The dramatic change in the surface morphology has been observed with increasing content of CSA in PPy matrix. The AFM study shows porous uniform globular morphology. The UV–vis spectra of CSA doped PPy film was found to shift to a lower wavelength side as compared to those of observed in PPy, indicating synergetic interaction between dopant CSA and PPy. CSA doped PPy not only can maintain a good solubility but also enhance the electrical conductivity. The results of dc electrical conductivity shows that, increase in electrical conductivity of PPy with increasing content of CSA (10–50%) in PPy matrix.     

A Method and Device for the Study of Low-Frequency Permittivity of Thin Amorphous Ice Films with Computer Data Recording

An alternating current is passed through an electrical capacitor filled with the sample studied. The signal, which is proportional to the current, is amplified, rectified, integrated, and recorded by a computer using a simple analog-to-digital converter consisting of a time-charging RC circuit and a comparator connected to the COM port. The measurement error does not exceed 1%. The permittivity is calculated by the electrical conductivity data with a 10% error.     

Nondestructive measurement and high-precision evaluation of the electrical conductivity of doped GaAs wafers using microwaves

A nondestructive method for measuring the electrical conductivity of doped GaAs wafers using a compact microwave instrument is presented. Based on the characteristics of the microwave detector and the fact that the microwave measurement is independent of the thickness of the wafer, the analytical and explicit expressions to evaluate the electrical conductivity of the wafer are derived. Using this method, only the voltages of the reflected signals for two wafer samples whose conductivities are known are required to calibrate the two undetermined constants in the equation. Then, the conductivity of any other wafer can be evaluated by substituting the measured voltage of the reflected signal into the explicit expressions. Seven different doped GaAs wafers with thickness larger than 350 μm and conductivities in the range of 1.3 × 10(4) S/m to 7.6 × 10(4) S/m are measured in the experiment, two of which are used for calibration. The evaluated results agree well with those obtained by the conventional Hall effect measurement method, with an evaluation error less than ±4.5%. The proposed method is potentially useful for the contactless and nondestructive evaluation of the electrical conductivity of any kind of semiconductor wafer.     

Fabrication of copper–TiC–graphite hybrid metal matrix composites through microwave processing

The significant requirements such as wear resistance and better tribological properties in addition to good electrical conductivity necessitate the development of copper-based advanced metal matrix composites for electrical sliding contact applications. Though the addition of graphite to copper matrix induces self-lubricating property, the strength of the composite reduces. The improvement in the strength of the composite can be achieved by reinforcing harder ceramic particles such as SiC, TiC, and Al₂O₃. In this paper, the development of hybrid composite of copper metal matrix reinforced with TiC and graphite particles through microwave processing was investigated. The effects of TiC (5, 10, and 15 vol.%) and graphite (5 and 10 vol.%) reinforcements on physical and mechanical properties of microwave-sintered copper–TiC–graphite hybrid composites are discussed in detail. Micrographs show the uniform distribution of reinforcements in copper matrix. Microwave-sintered composites exhibited higher relative density, sintered density, and hardness compared with conventionally sintered ones.     

Characterisation of a high concentration ionic bubble column using electrical resistance tomography

Attentions has been given to ionic liquids as an alternative physical solvent for carbon dioxide (CO₂) absorption because of their potential for gas selectivity, absorption capacity and low desorption energy by tailoring the molecules. Ionic liquid normally have a high viscosity, which influences the performance of absorption processes, and therefore, efficiency. This study investigates the hydrodynamics of ionic liquids in a two-phase gas–liquid flow by determination of the bubble formation, distribution of gas and bubble velocity profiles. A dual plane electrical resistance tomography (ERT) system and an optical imaging device were applied to a bubble column reactor of 50 mm internal diameter for the study. The model ionic liquids were aqueous solutions of sodium chloride (NaCl) with conductivity adjusted by altering the concentration of NaCl. Gas holdup has been estimated by analyses of conductivity data obtained from ERT by application of Maxwell's relationship which reveals significant increase in gas holdup as ionic concentration increases and is in good agreement with other studies.     

Conductive and Tribological Properties of Lithium-Based Ionic Liquids as Grease Base Oil

This article reports several conductive greases prepared by ionic liquids (ILs) that are synthesized by mixing lithium tetrafluoroborate (LiBF₄) or lithium bis(trifluoromethane-sulfonyl) imide (LiNTf₂) in diglyme (G2) and tetraglyme (G4) with appropriate weight ratios at room temperature (RT). The ILs have good solution in poly(ethylene glycol-ran-propylene glycol) monobutyl ether (PAG) and thus can be used as a base oil for preparing grease for steel–steel contacts. The electrical conductive properties of the grease prepared with the mixed oil of PAG plus ILs were evaluated using the DDSJ-308A conductivity tester, GEST-121 volume surface resistance tester, and HLY-200A circuit resistance tester. Combining the free volume with viscosity, the conductivity is inversely proportional to viscosity. The tribological properties were investigated using an MFT-R4000 reciprocating friction and wear tester. The results demonstrated that the prepared greases possess better conductive and tribological properties than the commercial grease with Cu powder as an additive.     

高温燃烧水解离子色谱法测定地质样品中氟氯溴

本文建立了一种快速、高效、无干扰且同时测定地质样品中氟氯溴的高温燃烧水解离子色谱方法。优化并确定了高温燃烧水解的最佳试验条件,采用电导检测离子色谱法测定氟、氯,电化学检测离子色谱法测定溴,获得了准确可靠的结果。通过测定氟、氯、溴含量不同的8个不同含量的国家一级标准样品,测定了该方法的精密度和准确度。结果表明：氟的相对标准偏差小于5%,相对误差均小于10%;氯、溴的相对标准偏差均小于10%,氯的相对误差均小于10%,溴的相对误差均小于13%,该方法氟、氯、溴的检出限分别为3×10^-6、19×10^-6、0.4×10^-6,能满足对地质样品中氟氯溴的分析要求。     

Prediction of phonon and electron contributions to thermal conduction in doped silicon films

The modified electron-phonon interaction model is proposed, and the relative contributions of phonons and electrons to the thermal conduction in doped silicon films are investigated quantitatively. The carrier contributions in sub-micro scale heat conduction are validated by an order of magnitude analysis and comparison with previous data. The simulation results show that the electron contribution in Si-layer is not negligible when the doping concentration is higher than 10¹⁹ cm^?3, which can be classified as semimetal or metal by the value of its electrical resistivity at 300 K. The electron thermal conductivity increases with increasing doping density, and its fraction is about 57.2% of the total thermal conductivity when the doping concentration is 5.0 × 10²⁰ cm^?3 and silicon film thickness 100 nm.     

基于气液两相流模型的电解加工多场耦合仿真

针对电解加工产生的气泡影响加工精度的问题,引入Euler Euler双流体模型对电解加工中气液两相流场进行描述,并耦合电场和温度场相关模型,分析了工具阴极、工件阳极表面气泡率、温度、电导率和电流密度的分布规律;通过调整加工电压、入口压力和出口压力,对工件阳极表面气泡率和电流密度分布进行仿真优化。仿真结果表明：在流速相同的条件下,减小加工电压、增加出口压力能够改善电导率分布,使阳极表面电流密度分布更加均匀。实验结果表明：仿真得到的阳极表面电流密度分布与工件轮廓高度误差分布吻合;采用优化后参数加工出的工件轮廓精度得到提高。     

Online conductivity calibration methods for EIT gas/oil in water flow measurement

Electrical Impedance Tomography (EIT) is a fast imaging technique displaying the electrical conductivity contrast of multiphase flow. It is increasingly utilised for industrial process measurement and control. In principle, EIT has to obtain the prior information of homogenous continuous phase in terms of conductivity as a reference benchmark. This reference significantly influences the quality of subsequent multiphase flow measurement. During dynamic industrial process, the conductivity of continuous phase varies due to the effects from the changes of ambient and fluid temperature, ionic concentration, and internal energy conversion in fluid. It is not practical to stop industrial process frequently and measure the conductivity of continuous phase for taking the EIT reference. If without monitoring conductivity of continuous phase, EIT cannot present accurate and useful measurement results. To online calibrate the electrical conductivity of continuous phase and eliminate drift error of EIT measurement, two methods are discussed in this paper. Based on the linear approximation between fluid temperature and conductivity, the first method monitors fluid temperature and indirectly calibrates conductivity. In the second method, a novel conductivity cell is designed. It consists of a gravitational separation chamber with refreshing bypass and grounded shielding plate. The conductivity of continuous phase is directly sensed by the conductivity cell and fed to EIT system for online calibration. Both static and dynamic experiments were conducted to demonstrate the function and accuracy the conductivity cell.     

Effect of cold compression on precipitation and conductivityof an Al–Li–Cu alloy

Transmission electron microscopy has been used to investigate the effect of increasing the degree of deformation applied by cold compression on the ageing kinetics and electrical conductivity response of an Al–Li–Cu alloy containing Mg and Ag. When cold compressed greater than 3%, the increased dislocation density accelerates the widespread precipitation of the T₁ phase resulting in an enhanced age hardening response. The lengthening rate of T₁ precipitates is also reduced in this cold compressed condition owing to the reduced local solute supersaturation, a result of the widespread precipitation of T₁ plates. Cold compression by less than 3% does not increase the age hardening response, and the precipitation of GP zones/θ″ appears to be suppressed. Precipitation of the T₁ phase is also not significantly enhanced compared with that of the more than 3% cold compressed conditions. The anomalous decrease in electrical conductivity is associated with the nucleation and growth of the T₁ phase. Strain fields around T₁ precipitates combined with the increased volume fraction of T₁ are thought to be the cause of the anomalous conductivity behaviour.     

Assessment of the possibilities of the dual-energy X-ray absorptiometry of multicomponent samples with variable content

Possibility of the employment of a linear coupling equation of mass attenuation coefficients for two energies for the density determination by dual-energy X-ray absorptiometry of multicomponent samples with variable content was theoretically approved and experimentally demonstrated. The relative error of the density measurements of aqueous-salt and aqueous-alcoholic solutions is 0.5% with a maximum change of the mass attenuation coefficient for the K _α line of zirconium being 70%.     

Enhancing electrical conductivity and electrical thermal characteristics of a PEDOT:PSS thin layer by using solvent treatment and adding Ag nanoparticle solution

A method of enhancing the electrical conductivity of 3,4-ethylenedioxythiophene:poly styrene sulfonate (PEDOT:PSS) by combining solvent treatment (adding high polar solvent: 5 wt% ethylene glycol) and adding a small amount of silver (Ag) nanoparticles in a solution was investigated. The main purpose of this was to apply a PEDOT:PSS conductive layer to micro-thermal devices driven by electricity and, for this, to reduce the layer thickness (for low stiffness) while maintaining necessary high electrical conductivity. Layers with thicknesses of less than about 10 μm were examined for electrical conductivity and temperature when electricity was applied. The solvent treated PEDOT:PSS had suitable electrical resistance to generate appropriate temperature properties. The added Ag nanoparticles reduced the electrical resistance by 30–70% over the measured thickness range. The electric conductivity applied with this method was 200–260 Ω⁻¹ cm⁻¹ for thicknesses of 1–2 μm (conductive area: 12 mm × 10 mm) and the generated temperature increase was 20–50 °C at applied voltages of 3–5 V. These characteristics are considered to be suitable to use the conductive layer as a heating element. In addition, the method we used scarcely degraded the transparency of the layer. Measurements of the conductive area in a layer with conductive atomic force microscope (AFM) indicated that the added Ag nanoparticles contributed to increasing the conductive areas and distributing them more uniformly.     

基于单片机控制的ECPR光功率数据采集系统

电定标热释电辐射计ECPR（Electrically Calibrated Pyroelectric Radiometer）是测量光辐射功率的一种高精度电替代绝对辐射计ESR（Electrical Substitution Radiometer），它通过使用光信号加热热释电表面和电加热热释电器件表面相等效的基本原理，通过测量电加热的功率值，并通过误差测量和分析加以修正该测量值，从而得到光功率值。它将光功率的测量标准溯源到电功率的标准上来，这样测量具有很高的精度。通常可以达到1％的不确定度。介绍了利用单片机和A／D器件等构成的光电信号采集系统，通过该系统可以测量由光功率等效成的电功率，从而获得光功率值。     

Analysis of viscosity effect on turbine flowmeter performance based on experiments and CFD simulations

Viscosity effect is one important factor that affects the performance of turbine flowmeter. The fluid dynamics mechanism of the viscosity effect on turbine flowmeter performance is still not fully understood. In this study, the curves of meter factor and linearity error of the turbine flowmeter changing with fluid viscosity variations were obtained from multi-viscosity experiments (the viscosity range covered is 1.0×10^–6 m²/s–112×10^–6 m²/s). The results indicate that the average meter factor of turbine flowmeter decreases with viscosity increases, while the linearity error increases. Furthermore, Computational Fluid Dynamics (CFD) simulation was carried out to analyze three-dimensional internal flow fields of turbine flowmeter. It was demonstrated that viscosity changes lead to changes of the wake flow behind the upstream flow conditioner blade and the flow velocity profile before fluid entering turbine rotor blade, which affect the distribution of pressure on the rotor blades, so impact the turbine flowmeter performance.     

Evaluation of surface roughness and nanostructure of indium tin oxide (ITO) films by atomic force microscopy

Indium tin oxide was deposited on a glass (soda lime glass) by radiofrequency sputtering system at different sputtering gas (argon/oxygen 90/10%) pressures (20-34 mTorr) at room temperature. The sputtering rate was affected by the sputtering gas pressure. The optimum sputtering gas pressure was found to be 27 mTorr. The samples at different thicknesses (168, 300, 400, 425, 475, 500 and 630 nm) were deposited on the substrate. Transparency, electrical conductivity and surface roughness of the films were characterized. The samples were annealed at 350, 400 and 450 degrees C to evaluate annealing process effects on the concerned parameters and, therefore, the above-mentioned measurements were repeated again. The films exhibited reasonable optical transmittance and electrical conductivity and greatly improved after annealing. The characterization was focused on the scanning of the film surfaces before and after annealing, which has a prominent effect on the optical properties of the films. Film surfaces were scanned by scanning probe microscopy in contact atomic force mode. The most consideration was devoted to image analysis.     

Measurement of the viscosity of biodiesel by using an optical viscometer

In this paper, we report the characterization of the viscosity of biodiesel produced from jatropha curcas. The viscosity measurement has been carried out by using a modified falling ball viscometer as well as optical technology. The viscosity was measured from 28 to 70 °C, which is the interest for determining the quality of biodiesel. We found that the falling ball optical viscometer offers a resolution of a viscosity measurement of ±0.039 mPa s with a relative error of 1.47933%. The measurement process was compared with a commercial viscometer, and it has been demonstrated that the biodiesel produced in Chiapas has good quality.     

Effect of friction stir processing parameters on the microstructural and electrical properties of copper

Friction stir processing (FSP) is an innovative technology, based on friction stir welding (FSW) operative principles, which can be used for changing locally the microstructure and the mechanical properties of conventional materials. In this work, the copper alloy C12200 was friction stir processed using two distinct tools, i.e. a scrolled and a conical shoulder tool, in order to promote different thermomechanical conditions inside the stirred volume, and consequently, varied post-processed microstructures. The influence of the tool geometry and tool rotation and traverse speeds on the microstructural and electrical properties of the processed copper alloy was analysed. The processing conditions were found to have an important influence on the electrical conductivity of the processed material. The differences in electrical conductivity were explained based on dislocations density effects. The effect of the dislocations density on electrical conductivity of the processed material was found to prevail over the effect of the grain boundaries.     

Ultrahigh vacuum-compatible fabrication and electrical characterization systems for environmentally sensitive metal oxide semiconductor capacitors

We describe an integrated, ultrahigh vacuum system for metal oxide semiconductor (MOS) device fabrication and characterization. This system is advantageous for electrical property measurements on electronic devices with environmentally sensitive materials and is especially important as device dimensions approach the nanoscale. Without exposure to atmosphere, MOS capacitors were fabricated by evaporatively depositing gate metal on molecular-beam-epitaxy (MBE) grown dielectrics through a shadow mask in an UHV electrode-patterning chamber. Finished devices were transferred in UHV to an in situ UHV electrical characterization probe station. We obtained excellent agreement between air-ambient ex situ and in situ probe station measurements with less than 0.3% systemic error for frequencies from 20 Hz to 1 MHz. We have successfully measured MOS capacitors with sensitivity to a density of interface states of 1x10(10) states cm(-2) eV(-1). These measurements show 0.5% systematic error for measurement frequencies from 20 Hz to 1 kHz and less than 0.1% from 1 kHz to 1 MHz. The integrated system presented here is one where complex, MBE-grown MOS heterostructures can be synthesized and tested rapidly to explore new field-effect-device physics and functionality.     

Imaging of the magnetic field structure in megagauss plasmas by combining pulsed polarimetry with an optical Kerr effect shutter technique

Pulsed polarimetry in combination with a high speed photographic technique based on the optical Kerr effect is described. The backscatter in a pulsed polarimeter is directed through a scattering cell and photographed using an ～1?ps shutter, essentially freezing the intensity pattern. The image provides both the local electron density and magnetic field distributions along and transverse to the laser sightline. Submillimeter spatial resolution is possible for probing wavelengths in the visible due to the high densities and strong optical activity. Pulsed polarimetry is thereby extended to centimeter-sized plasmas with n(e)>10(19)-10(20)?cm(-3) and B>20-100?T (MG) produced by multiterawatt, multimega-ampere electrical drivers, wire Z pinches, and liner imploded magnetized plasmas.