Transmission analysis of electromagnetic induction RFID system

The transmission characteristics of the electromagnetic induction RFID systems are greatly influenced by the distance between the primary and secondary antenna coils and by the materials used in their design. In this paper the induced current of the secondary antenna coil is calculated by the 3D finite element method when both the primary and secondary antenna coils are operated in resonant circuits. The influences of the analyzed parameters on the transmission characteristics are demonstrated. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(4): 38–45, 2010; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21019     

Fundamental Study of Voltage Stability in a Power System with Large Penetration of Photovoltaic Generation Considering Induction Motor Dynamics

Because of global warming, attention to photovoltaic (PV) generation has increased, and considerable PV generation capacity will be installed in the power system. In Japan, most PV generation will be connected to the distribution system, which will cause changes in power flow in the power system. Forward power flow (flow from the higher voltage system to the lower voltage system) will be reduced and reverse power flow may occur. Because of the change in power flow, the voltage characteristics will also be changed. Consequently, it is expected that the penetration of PV generation will have some impact on voltage stability. In previous studies, the voltage characteristics in a simple power system model consisting of one infinite bus, one load, and one PV power source, have been investigated. It was found that there is not only a forward power flow limit but also a reverse power flow limit (the left nose in the PV curve), and that when the output power from PV generation is very large, the left nose sometimes has some impact on voltage stability. In this paper, the voltage stability in a simple power system model considering the dynamics of an induction motor is discussed.     

Carrier separation analysis for clarifying carrier conduction and degradation mechanisms in high-k stack gate dielectrics

The carrier conduction and the degradation mechanism in n⁺gate p-channel metal-insulator-semiconductor field-effect-transistors with HfAlO_X (Hf: 60 at.%, Al: 40 at.%)/SiO₂ dielectric layers have been investigated using carrier separation method. Since gate current depends on substrate bias and both electron and hole currents are independent of temperature over the range of 25–150 °C, the conduction mechanism for both currents is controlled by a tunneling process. As the interfacial SiO₂ layer (IL) thickness increases in a fixed high-k layer thickness (T_high-k), a dominant carrier in the leakage current changes from hole to electron around 2.2-nm-thick IL. This is due to an asymmetric barrier height for electrons and holes at the SiO₂/Si interface. On the contrary, in the case of a fixed IL thickness of 1.3 nm, the hole current is dominant in the leakage current, regardless of T_high-k. It is shown that the dominant carrier in the leakage current depends on the structure of the high-k stack. Both electron and hole currents for the stress-induced-leakage-current (SILC) state increase slightly relative to the initial currents, which means that the trap generation in the high-k stack occurs near both the conduction band edge of n⁺poly-Si gate and the valence band edge of Si substrate. The electron current at soft breakdown (SBD) state dramatically increases over that for the SILC state, while the hole currents for both the SILC state and SBD are almost the same. This indicates that the defect sites generated in the high-k stack after SBD are located at energies near the conduction band edge of n⁺poly-Si gate. Both the defect generation rate and the defect size in the HfAlO_X/SiO₂ stacks are large compared with those in SiO₂. It is inferred that, in high-k dielectric stack, the defect generation mainly occurs in the high-k side rather than the IL side, and the defect size larger than the case of SiO₂ could be related to a larger dielectric constant of the high-k layer.     

Mechanistic Analysis of Dislocation Damping in Single-Crystal Magnesia Close to Its Melting Point

Single-crystal magnesia (MgO) that contained 0.004 wt% of iron as a major impurity was tested in torsional geometry, with respect to its damping response, up to temperatures close to its melting point. The MgO crystal was oriented so that maximum shear stress would be applied along the (110)<110> primary slip system of its rock-salt cubic structure. Damping data were also collected as a function of torsional strain amplitude and analyzed according to a proposed mechanistic procedure for metallic alloys. The amplitude-dependent decrement of the single-crystal MgO at moderate strain amplitudes (10⁻⁵−10⁻⁴) qualitatively followed the predictions of the hysteretic dislocation damping theory (i.e., Granato-Lücke theory). Using the results of this analysis, the binding energy that controlled dislocation motion was calculated from damping data. In addition, an attempt to semiquantitatively discuss the dislocation/atom binding energy in comparison with the theoretical prediction for the solute-atom pinning mechanism has also been presented.     

Cell Profiling Based on Sugar-Chain–Cell Binding Interaction and Its Application to Typing and Quality Verification of Cells

Developing methods to determine cell type and cell state has been a significant challenge in the field of cancer diagnosis as well as in typing and quality verification for cultured cells. Herein, we report a cell profiling method based on binding interactions between cell-surface sugar-chain-binding proteins and sugar-chain-immobilized fluorescent nanoparticles (SFNPs), together with a method for cell typing and cell quality verification. Binding profiles of cells against sugar chains were analyzed by performing flow cytometry analysis with SFNPs. Discrimination analysis based on binding profiles could classify cell type and evaluate the quality of cultured cells. By applying our method to differentiated cells originating from conventional cell lines and also to mouse embryotic stem cells, we could detect the cells before and after differentiation. Our method can be utilized not only for the biofunctional analysis of cells but also for diagnosis of cancer cells and quality verification of cultured cells.     

System Reduction of Power System with Penetration of Photovoltaic Generations

This paper presents a novel system reduction method which makes it possible to consider the impact of photovoltaic (PV) penetration on transient stability precisely. The object system for system reduction can be aggregated into a simple equivalent circuit by using the proposed method. The equivalent circuit consists of a lumped load model, a lumped PV model, and three equivalent impedances. Using the equivalent circuit, power flow into the object system when the system voltage changes can be analyzed without repeated power flow calculation of the original system. In order to verify the proposed method, this paper presents a numerical example of transient stability analysis with a one‐generator‐to‐infinite‐bus system model. The results of analysis indicate that transient stability considering PV penetration can be analyzed with high accuracy with the proposed method.     

Design, Synthesis, and Catalysis of Bio-inspired Immobilized Metallocomplex Catalyst

Novel immobilized metallocomplex catalyst based on bio-inspired concept has been developed. The allyl functional group in the anionic chelating ligand reacts with thiols to give the linker for immobilization. The immobilization of the chelating ligand onto amorphous silica supports results in the isolated metal-binding sites giving the coordinatively unsaturated metal center. The biomimetic iron complex-immobilized silica exhibits the catalysis for olefin epoxidation with aqueous H₂O₂ at ambient temperature.     

Generation of Femtoliter Reactor Arrays within a Microfluidic Channel for Biochemical Analysis

We present a simple microfluidic method to generate high-density femotoliter-sized microreactor arrays within microfluidic channels. In general, we designed a main channel with many small chambers built into its walls. After sequentially infusing aqueous solution and organic solvent from a single tube into the device, aqueous droplets are confined in the chambers by the solvent flow. The generated reactors are small and stable enough for carrying out ultrasensitive biochemical assays at single molecule levels. As a demonstration, in this paper, we optically observed hydrolysis activity of β-galactosidase enzymatic molecules in the reactor arrays at single molecule levels. Further, this method has the following advantages: (1) the droplets are observable immediately after formation and (2) its simple procedure is sufficiently robust such that even handy infusion of the preloaded solutions is reproducible. We believe our method provides a platform attractive to a variety of single molecule studies and sensing applications such as clinical diagnostics.     

Eliminating child labour in Malawi: a British American Tobacco corporate responsibility project to sidestep tobacco labour exploitation

Objectives

To examine British American Tobacco and other tobacco industry support of the Eliminating Child Labour in Tobacco Growing Foundation.

Design

Analyses of internal tobacco industry documents and ethnographic data.

Results

British American Tobacco co‐founded the Eliminating Child Labour in Tobacco Growing Foundation (ECLT) in October 2000 and launched its pilot project in Malawi. ECLT''s initial projects were budgeted at US$2.3 million over four years. Labour unions and leaf dealers, through ECLT funds, have undertook modest efforts such as building schools, planting trees, and constructing shallow wells to address the use of child labour in tobacco farming. In stark contrast, the tobacco companies receive nearly US$40 million over four years in economic benefit through the use of unpaid child labour in Malawi during the same time. BAT''s efforts to combat child labour in Malawi through ECLT was developed to support the company''s “corporate social responsibility agenda” rather than accepting responsibility for taking meaningful steps to eradicate child labour in the Malawi tobacco sector.

Conclusion

In Malawi, transnational tobacco companies are using child labour projects to enhance corporate reputations and distract public attention from how they profit from low wages and cheap tobacco.     

Numerical study of flow and heat-transfer characteristics of cryogenic slush fluid in a horizontal circular pipe (SLUSH-3D)

Cryogenic slush fluids, such as slush hydrogen and slush nitrogen, are two-phase, single-component fluids containing solid particles in a liquid. Since their density and refrigerant capacity are greater than those of liquid-state fluids alone, there are high expectations for use of slush fluids as functionally thermal fluids in various applications, such as fuels for spacecraft engines, clean energy fuels to improve the efficiency of transportation and storage, and as refrigerants for high-temperature superconducting equipment. In this research, a three-dimensional numerical simulation code (SLUSH-3D), including the gravity effect based on the thermal non-equilibrium, two-fluid model, was constructed to clarify the flow and heat-transfer characteristics of cryogenic slush fluids in a horizontal circular pipe. The calculated results of slush nitrogen flow performed using the numerical code were compared with the authors’ experimental results obtained using the PIV method. As a result of these comparisons, the numerical code was verified, making it possible to analyze the flow and heat-transfer characteristics of slush nitrogen with sufficient accuracy. The numerical results obtained for the flow and heat-transfer characteristics of slush nitrogen and slush hydrogen clarified the effects of the pipe inlet velocity, solid fraction, solid particle size, and heat flux on the flow pattern, solid-fraction distribution, turbulence energy, pressure drop, and heat-transfer coefficient. Furthermore, it became clear that the difference of the flow and heat-transfer characteristics between slush nitrogen and slush hydrogen were caused to a large extent by their thermo-physical properties, such as the solid–liquid density ratio, liquid viscosity, and latent heat of fusion.