Thermodynamic and transport properties of CO2, CO2–O2, and CO2–H2 mixtures at temperatures of 300 to 30,000 K and pressures of 0.1 to 10 MPa

This paper provides the theoretical calculation results of thermodynamic and transport properties of CO₂, CO₂–O₂ mixture, CO₂–H₂ mixture under thermal equilibrium condition at temperatures of 300 to 30,000 K and at pressures of 0.1 to 10 MPa. The gas CO₂ is one of the candidates for the environmentally benign arc‐quenching medium in a circuit breaker. Furthermore, the effect of additional gases O₂ and H₂ on the thermodynamic and transport properties of CO₂ was also investigated in this paper. The hydrogen atom included CO₂ is similar to the polymer ablated vapor in switching devices. First, equilibrium compositions of CO₂, CO₂–O₂ mixture, CO₂–H₂ mixture were calculated through the Gibbs free energy minimization method. Second, thermodynamic properties were computed using the calculated composition. Finally, transport properties were calculated by the first‐order approximation of Chapman– Enskog method using the collision integrals between species. Inclusion of H₂ increases the electrical conductivity of CO₂ in the range 3000 to 6000 K because CHO molecules produced in this temperature range emit more electrons due to the lower ionization potential of CHO. It also increases the thermal conductivity of CO₂ especially due to dissociation reactions of H₂ around 3900 K and ionization of H around 15,000 K. These properties provided here can be used for CO₂ thermal plasma simulation. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(4): 18–29, 2008; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20467     

常压空气介质阻挡放电的能量传递过程

利用发射光谱技术分析空气等离子体中可能存在的化学活性物质,并通过分析空气等离子体中氮气、氧气常见激发态的产生和猝灭过程,结合其动力学数据,计算分析了常压空气介质阻挡放电中的能量传递过程。结果表明,氮分子和原子的激发态很快通过与分子、原子间的碰撞而猝灭掉或被氧分子、原子氧化而生成氮氧化合物,氧分子的激发态由于其本身的跃迁几率太小,所以没有测到氧气的发射光谱;放电系统中的电子能量很少有17.0 eV的,但存在能量11.03 eV的电子,与计算得到的电子能量分布一致;约化场强E/N150 Td时,电子与氮分子激发、离解碰撞的能量损失占电子碰撞能量损失的50%以上;氮分子、原子激发态的存在可以提高O、O3以及一些氮氧化合物的粒子数浓度。     

High‐efficiency CMOS push‐pull power amplifier with multilayer center‐tapped transformer

This paper describes the design of a push‐pull power amplifier (PA) with a center‐tapped transformer for transmitter applications on the 5.2‐GHz band using 0.18μm CMOS technology. The type of the proposed PA is based on a double‐ended push–pull (DEPP) configuration. DEPP has a simple construction with only transistors and transformers. The PA has reverse‐phased cascode‐connected transistors. The proposed transformer has a multilayer structure and was designed using electromagnetic field simulation. To achieve high power added efficiency (PAE), we assumed the optimized output impedance technique with a tunable impedance antenna. The PA has 13.2 dB linearity gain, 14.9 dBm 1‐dB compression point (P1dB), and 27.4% maximum PAE. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Effect of polymer ablation gas on arc quenching properties around current zero

The influence of polymer ablation on arc properties such as the temperature distribution and arc conductance in the current decay process was investigated by numerical approaches. A numerical thermofluid model was developed for a simplified circuit breaker with POM or PTFE ablation. In this model, thermal plasma‐polymer solid coupling phenomena such as melting and evaporation were taken into account without any empirical model based on measurements, unlike other existing numerical thermofluid models. The dominant process for the decay of arc conductance was examined by changing the thermodynamic parameters such as the melting and boiling temperatures of solid polymers, or the thermal conductivity and electrical conductivity of the ablation gas. It was found that the gas density, thermal conductivity, and electrical conductivity of the ablation gas were more effective for decaying arc conductance than any other thermodynamic parameters. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(3): 32–45, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22274     

Numerical Simulation of Power Generation Characteristics of a Disk MHD Generator with High‐Temperature Inert Gas Plasma

The power generation characteristics of a disk magnetohydrodynamics (MHD) generator with high‐temperature inert gas (argon) plasma have been examined by a time‐dependent two‐dimensional numerical simulation. The numerical simulation results based on the experimental conditions show that the enthalpy extraction ratio (= electrical output power/thermal input) can reach above 10%, which surely supports the reasonability of the experimental results. Proper selection of working conditions, especially the inlet total gas temperature, is necessary, since the gas temperature dominantly determines the electrical conductivity in the generator, unlike the conventional seeded plasma MHD generator. It is also found that the plasma is not in the recombination process but in the ionization process, where the ionization degree moderately increases along the flow. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(3): 23–30, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21237     

Structure change of PTFE by low‐energy ion irradiation. Restraint of structure collapse by crosslinking structures

The authors irradiated PTFE (polytetrafluoroethylene) with low‐energy nitrogen ions (100 eV) for surface modification. However, PTFE cannot be expected to show improvement in adhesive strength because it is a degradation‐prone polymer and surface fatigue is produced by ion irradiation. We focused on cross‐linked structure to solve this problem. PTFE was changed from a degradation‐prone polymer into a cross‐linked polymer by raising the temperature above the glass‐transition temperature during ion irradiation. As a result, the formation of CF₃ bonds was inhibited and degradation was prevented by ion irradiation above the glass‐transition temperature. In addition, combined consideration of the C1s spectrum and the density profile suggests that a cross‐linked structure is effective for improvement of adhesive strength. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(4): 1–7, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21225     

Formation and properties of nitrogen‐rich phases in austenitic stainless steel by plasma‐based ion implantation

Surface modification of austenitic stainless steel by plasma‐based ion implantation at elevated temperatures below 450°C has been studied experimentally. The nitrogen depth profile at room temperature was similar to that obtained by TRIM code simulation, but the depth of nitrogen penetration increases with target temperature and reaches a few micrometers at a treatment condition of 450°C and an implantation time of 2 h. High‐dose nitrogen implantation exceeding 10¹⁸ cm^?2 at temperatures above 350°C results in the formation of expanded austenite phase (supersaturated f.c.c. phase) with little CrN precipitation, leading to remarkable enhancement of surface hardness without loss of corrosion resistance. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(4): 9–16, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10340     

Fundamental characteristics of a MEMS‐diaphragm actuator using a thermal expansion drive composed of a conductive polymer

Performance of a MEMS actuator using a thermal expansion drive of a conductive polymer (CP) is investigated by applying electricity to it. The actuator consists of a thin polymer diaphragm (5 mm diameter) and a thin CP (ion‐doped polythiophene) layer coated on the diaphragm surface. Polyimide (10 μm thickness) and PET (110 μm thickness) sheets were chosen as the diaphragm materials. The diaphragm is deflected by the thermal expansion of the CP by applying electricity to it. Merits of using the CP instead of metal are realizing flexible actuators and the applicability to a low‐heat‐resistant material diaphragm. The relationship between thickness of the CP layer (10–50 μm thickness) and electrical resistance (30–600 Ω) and the relationship between the input voltage (1–8 V) and the generated diaphragm displacement (several tens of micrometers) were investigated experimentally. These relationships were compared with those in the case of using the thermal expansion of a vapor‐deposited aluminum layer (0.1 μm thickness). The results of the investigation indicate that the diaphragm based on CP can produce the required displacement. In the case the CP‐layer‐based thermal expansion, however, larger input voltage than in the case of the aluminum‐layer‐based thermal expansion is needed to obtain the same displacement amplitudes. Therefore, the main problem concerning use of the CP‐based diaphragm is considered to be enhancing the electrical conductance of the CP layer. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Free electron laser induced forward transfer method of biomaterial for marking

Biomaterial, such as chitosan and poly lactic acid, containing a fluorescence agent was deposited onto biologic hard tissue, such as teeth, the claws of dogs or cats, or a sapphire substrate by free electron laser induced forward transfer method for direct write marking. Spin‐coated biomaterial with the fluorescence agent Rhodamin 6G or zinc phthalocyanine target on a sapphire plate was ablated by a free electron laser (resonance absorption wavelength of biomaterial: 3380 nm). In particular, the influence of the spin‐coating film‐forming temperature on hardness and adhesion strength of the biomaterial is studied. The effect of resonance excitation of the biomaterial target by turning the free electron laser is discussed with respect to damage in terms of biomaterial, rhodamin‐6G, or zinc phthalocyanine for direct write marking. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(4): 60–66, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20795     

等离子弧淬火单片机控制系统的研究

等离子弧淬火热源装置热效率高,成本低,有巨大的发展潜力.等离子弧淬火单片机控制系统通过双反馈环节(高速反馈控制环节和低速总体趋势控制环节)实现淬火过程中对淬火电流的稳定控制,使系统在特殊干扰下或失控时工件得到快速保护而不被烧蚀.设计的等离子弧淬火单片机控制系统的控制过程具有智能调节功能,可提高工件淬火稳定性从而提高淬火...     

不同产气材料对电弧运动规律影响的实验研究

对低压断路器灭弧室内侧壁的非产气材料、迭尔林和尼龙进行了相关的实验,揭示了不同聚合体产气材料对空气电弧运动规律的影响。在电弧向灭弧栅片运动的过程中,聚合体材料受到电弧的烧蚀,灭弧室内充满空气和聚合体蒸汽的混合气体。建立了灭弧室实验模型,给出了大电流电弧的实验线路,并在500A和3000A电流时进行了电弧实验。研究结果表明,灭弧室内压力增大,加速电弧等离子体的运动速度,可有效提高断路器的性能。     

Photoemission study on natural oxidation of Cu3Au with synchrotron radiation

We report the results of a study of the natural oxidation of Cu₃Au(110) with high‐resolution X‐ray photoemission spectroscopy in conjunction with synchrotron radiation. The clean surface of Cu₃Au(110) is terminated with 50% Au and 50% Cu atoms. After natural oxidation in the air, Cu atoms segregate on the surface and produce Cu‐oxide. As a result, Au atoms move into the bulk. Au atoms below the oxide reduce the diffusion of O atoms farther into bulk and limit the oxide thickness. The face dependence of natural oxidation indicates that the diffusion of Cu atoms also contributes to oxide formation. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(4): 43–47, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21149     

New design and development of size‐selected gas cluster SIMS

A new cluster time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) was developed, using a size‐selected gas cluster ion as a projectile. Because a large gas cluster ion can generate numerous low‐energy constituent atoms during a collision with the surface, multiple and ultralow‐energy sputterings are induced. Dividing the acceleration energy of a gas cluster ion by the number of constituent atoms provides the mean kinetic energy of the constituent atoms. Hence, sputtering can be controlled to minimize decomposition of the sample molecules by precisely adjusting the number of constituent atoms (the cluster size) and/or the acceleration energy of the gas cluster ions. The cluster size was selected by the time‐of‐flight method using two ion deflectors attached along the ion‐beam line. A high resolution of 11.7 was achieved for the cluster size/size width (m/Δm) of the Ar‐cluster ions. The SIM spectra of poly(methyl methacrylate) (PMMA) were measured using the size‐selected gas‐cluster SIMS machine. The large fragment ions emitted from PMMA are enhanced as the cluster size increases. This result suggests that a large cluster ion projectile in which each constituent atom within the cluster has decreased kinetic energy inhibits the decomposition of the polymer structure. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(3): 52–58, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21159     

A permanent magnet‐assisted synchronous reluctance motor

Permanent magnet motors have attracted a lot of attention recently for their potential for saving energy. However, they are only used for certain applications because the magnets are expensive. This paper discusses the optimum design of the low‐cost, highly efficient magnet‐ assisted reluctance motors with a minimum amount of magnets. The motor considered in this study is a multi‐flux barrier reluctance motor. The configuration by which permanent magnets are embedded to the innermost side of the rotor to obtain maximum output with the minimum amount of magnets was evaluated through simulation and experiments with a prototype motor. As a result, we established a method for designing motors capable of realizing the same efficiency as permanent magnet motors with only one‐fourth the amount of magnets. In our experiments, we achieved a high efficiency of 94.5% with a 750‐W motor. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 142(4): 66–74, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10123     

Performance evaluation of SOFC systems using electrochemical partial oxidation of methane

We simulated the performance of systems using a solid oxide fuel cell (SOFC) stack which generates electricity by electrochemical partial oxidation of methane and a conventional steam‐reforming‐type SOFC (SRSOFC) stack. The net thermal efficiency in an atmospheric partial‐oxidation‐type SOFC (POSOFC)‐SRSOFC system was 8% higher than that in an atmospheric SRSOFC system at system outputs of 35 kW or more. The net thermal efficiency of a pressurized POSOFC‐SRSOFC‐gas turbine (GT) system was slightly higher than that of a pressurized SRSOFC‐GT system. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(4): 11–19, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10314     

Performance analysis of closed loop in a CCMHD single power generation system

Results of numerical study on performance of closed loop in the CCMHD single power generation system are presented. The small closed loop with thermal input of 2.3 MW was designed. The fluid‐dynamical and thermal performance of the closed loop was calculated for the first time by one‐dimensional numerical simulation. The result indicates that pressure loss and heat loss are large in the designed small closed loop. The large pressure loss was due to the wall friction or the pebble bed and it occurred at the supersonic nozzle, the MHD channel, and the regenerative heat exchanger used for argon cooling. The enthalpy extraction remained low (= 17.6%) owing to the large pressure loss and as a result, the thermal efficiency of the closed loop remained only 21.6%. The enthalpy extraction and the thermal efficiency became maximal at the optimal inlet total pressure of 0.60 MPa. At inlet total pressure lower than the optimal one, the electric conductivity, the flow velocity, and the electric efficiency became higher. However, the total pressure ratio (= exit/inlet) in the MHD channel became larger particularly at low inlet total pressure because of the increase in the pressure loss due to pebble bed and wall friction. These led to the existence of the optimal inlet total pressure. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(1): 27–38, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10118     

Inner code assisted parallel concatenated single parity check codes

This paper proposes a novel coding scheme to improve the performance of multidimensional parallel concatenated single parity check (PCSPC) codes. The high error floor of PCSPC codes prevents clear turbo cliff to be seen in the bit‐error rate (BER) performance. Based on the product accumulate type‐I (PA‐I) coding scheme, which adds serially an accumulator to the existing PCSPC code structure, our coding scheme considers a wide range of rate‐1 recursive systematic convolutional (RSC) codes replacing the accumulator. The convergence behavior of the proposed iterative decoding is monitored and analyzed using an extrinsic information transfer (EXIT) chart. It has been revealed from the EXIT chart analysis that the proposed coding scheme has a lower convergence threshold than the PA‐I coding scheme, especially when using a lower code rate PCSPC code as the outer code. For the 2D PCSPC(3,2) code with the code rate 0.5, the proposed coding scheme has a convergence threshold of 0.47 dB, whereas the convergence threshold of the PA‐I coding scheme is 0.81 dB. The convergence threshold of the proposed coding scheme is closer to theoretical limit (0.28 dB away from the theoretical limit) than that of the PA‐I coding scheme (0.62 dB away). However, for PCSPC codes with a higher code rate, the performance improvement of the proposed coding scheme with respect to the PA‐I coding scheme becomes smaller. A series of simulations is carried out to investigate the performance of the proposed coding scheme, and the simulation results show that better performance is achieved by using the proposed coding scheme compared with the PA‐I coding scheme. The simulation results show good consistency with the convergence threshold obtained from the EXIT chart, as the difference is only within 0.34 dB in all the evaluated cases. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Space- and surface-charge analysis of plasma-preprocessed PTFE thinfilms

The space- and surface-charge behavior of corona-charged polytetrafluoroethylene thin films after plasma processing were studied experimentally by space-charge density distribution measurement and thermally stimulated discharge current (TSDC) measurement. The effect of the antistatic process using low-pressure discharge plasma and charge elimination process dipping in tap water was examined. The surface composition of the samples which were plasma- processed was analyzed with X-ray photoelectron spectroscopy (XPS) to study the mechanisms of antistatic process. It was found that charge elimination of plasma-processed samples was enhanced, independently of the kind of processing gas during the plasma processing. Oxygen and nitrogen atoms were observed from the XPS measurement of plasma-processed samples. In particular, a large amount of nitrogen atoms was found on the surface of the samples plasma processed in pure nitrogen gas. The samples plasma processed in pure nitrogen gas showed a large hetero TSDC peak at room temperature before the charge-elimination process. This might be due to nitrogen atoms on the sample surface that were generated during plasma processing     

Identification of the parameters of the high‐frequency equivalent circuit of PM synchronous motor based on genetic algorithm

This paper presents an identification technique of parameters of a high‐frequency equivalent circuit of permanent magnet synchronous motors (PMSM) driven by a PWM inverter. The high‐frequency oscillatory currents such as leakage current to the motor frame (common‐mode current) and high‐frequency oscillatory line current (normal‐mode current) are generated by switching instants of inverter transistors. The parameters of the high‐frequency equivalent circuit of PMSM which can simulate the oscillating current are identified by means of genetic algorithm. It is shown that the high‐frequency equivalent circuit with identified parameters can generate the oscillating current by some simulation results. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(4): 57–66, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20717     

Thermal degradation characteristics of oil‐filled cable joint with extremely degraded tan δ oil

Much of oil‐filled (OF) cable has been used for a long time as 66‐ to 500‐kV extrahigh‐voltage cable. Sometimes we can see extremely degraded tan δ oil (several tens of percent of tan δ, for example) in joint boxes, etc. The values of tan δ calculated by a simple combination model of paper/oil show that the oil‐impregnated paper with such a high tan δ oil likewise has an extremely high tan δ, which must result in thermal breakdown. However, such an event has not taken place up to the present in actually operated transmission lines. This fact suggests that some mechanism for the suppression of tan δ has acted in the paper insulation impregnated with degraded tan δ oil. Therefore, we investigated in detail the tan δ characteristics of paper impregnated with extremely high tan δ oil. In addition, based on the investigation results, we developed a method for simulation of heat generation by dielectric loss in an OF cable joint (which has degraded tan δ oil). © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(1): 1–10, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21184