New tetrapolar circuit method using magnetic field for measurementof local impedance change in biological substances

A new tetrapolar circuit method using a magnetic field is proposed to measure the local electric impedance change in living tissue. Based on this method, we designed an apparatus which can detect impedance changes in closely-situated two parts of living tissue, simultaneously and independently. Using this apparatus, we showed the effectiveness of the proposed method by an in vitro experiment and by an in vivo measurement of pulsatile waveforms in the forearm arteries. The detection sensitivity for a local impedance change was confirmed to be higher than that of the conventional tetrapolar method. Pulsatile impedance waveforms measured in the radial and the ulnar parts of the forearm were consistent with those estimated from the anatomical structure.     

Effects of compressive strain on the evolution of interfacial strength of steel/nickel solid-state bonding at low temperature

Solid-state bonding between ultralow-carbon steel and pure nickel was conducted by hot pressing with various compressive strain ranging from 5 to 15% and subsequent isothermal holding at 923?K. It was found that the interfacial strength of contact area is accounted for by the evolution of the intrinsic strength of the interface and the amount of plastic energy dissipation at the crack tip during interface fracture. The compression induces severe deformation around the interface and consequently inhibits the plastic energy dissipation during interface fracture. In the first stage of isothermal holding, the residual strain around the interface on the steel side is reduced by recovery process, which concurrently decreases in the yield stress of the area adjacent to the interface. This promotes plastic energy dissipation of the area, leading to a significant increase in interfacial strength in the first stage.     

The relationship between acoustic emission signals and cutting phenomena in turning process

The development of intelligent manufacturing by using machine tools is advancing in leaps and bounds. To maintain accuracy in machining and in the interests of fail-safe operation, monitoring of the cutting state or the final machining is very important. Acoustic emissions (AE) comprise elastic stress waves produced as a result of the deformation and fracture of materials. By measuring the AE generated during a turning process, it is possible to estimate the state of the machining operation. The correlation between cutting phenomena and AE in a turning process was examined experimentally by using a steel workpiece and a cermet tool in a numerically controlled turning process. The process of formation of chips, the types of chip, and the shear angle all markedly affected the AE signals. There was a strong negative correlation between the shear angle and the AE signal level. Similar results were obtained for various feed rates and for workpieces of various degrees of hardness. Correlations related to surface roughness and to tool wear are also described that permit the evaluation of the state of the turning process.     

Simulation of transverse crack formation on continuously cast peritectic medium carbon steel slabs

Reliable data are limited to the critical strain for the formation of transverse cracks on the slabs, owing to experimental difficulty to simulate temperature gradient in solidified shell in continuous casting mold. The present study is to determine the critical strain, ?_c, for the formation of transverse cracks on continuously cast slabs. A convenient and simple hot tensile test using rectangular test pieces with either V-notch or semi-circle notch or oscillation marks has been developed by placing the specimen under similar temperature gradient to that in solidified shell in the mold. The ?_c has been determined at a better accuracy and reproducibility, and the ?_c at a strain rate of 5?10^?4s^?1 is found to be a high 35% for test pieces without notch. It sharply decreases, however, to 10% for those with V- and semi-circle-notches, slightly decreases with increasing notch depth, and further decreases for those with oscillation marks that accompany solute segregation. Reduction of the oscillation mark depth is shown to be important measure to prevent the occurrence of transverse cracking of continuously cast slabs.     

Observation of metal on Si(0 0 1) by STM/STS and its consideration based on the first principles calculations

Local density of states (LDOS) is obtained by the first principles calculation based on the density functional theory on the Si(0 0 1)2 × 1 surface and on the surface with an Al dimer. At an Al dimer, LDOS has a high intensity in the conduction band region, which cannot be seen on the Si(0 0 1)2 × 1 surface. This tendency is observed in STS measurements as well. The possibility for a microelementary analysis is presented by applying this method to other metal atoms on the Si surface. Furthermore, it is pointed out that STS measurements should be always performed at the same tip-sample separation to obtain reproducible STS spectrums.     

Potentials of GHG reductions from wastewater treatment for the CDM

The study aims to evaluate the potential of GHG (greenhouse gas) reductions by installing an anaerobic digester in a wastewater treatment facility in Southeast Asia. Then the break-even point of additional investment to reduce GHG is obtained by exchanging carbon price as emissions credits. In the project scenario, the wastewater treatment system has the digester, where methane (biogas) is produced and recovered. Compared with the baseline scenario, the biogas has calorific value to produce heat and electri...     

Analysis of human error in nursing care

Analysis of reports about incidental and accidental events in nursing care were made using a reliability engineering method. Unnatural working hours, such as evening duty, night duty falling next to a holiday, two consecutive night-duty shifts, and two consecutive evening-duty shifts were major factors in the occurrence of errors. In a mixed-division ward (a ward containing patients belonging to different divisions), rule-based errors happened more frequently than in a single-division ward. Also, less experienced nursing staffs made errors more frequently than experienced nursing staffs.     

220,000‐r/min, 2‐kW PM motor drive for turbocharger

This paper describes an ultrahigh‐speed permanent‐magnet synchronous motor drive, which is embedded in a turbocharger of an internal‐combustion engine. The electrical drive makes it possible to enhance output power of the turbocharger in a motoring mode and to retrieve combustion energy from exhaust gas in a regenerating mode. Computer simulations and experimental tests are conducted to examine various operation characteristics of a prototype. The experimental data demonstrate 220,000‐r/min operation at 2.2‐kW inverter output power, in good agreement with the simulation results and proving the feasibility of the proposed system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(3): 31–40, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20408     

Short‐current pulse‐based adaptive maximum‐power‐point tracking for a photovoltaic power generation system

This paper focuses on a maximum‐power‐point tracking method of photovoltaics via use of the short‐current pulse. It has been reported that the optimum operating current is proportional to the short current and that maximum‐power‐point tracking can be performed by detecting the short current. The proposed method utilizes the intermittent short‐current pulse to estimate the optimum operating current and its operating characteristics have experimentally been verified. Also, an adaptive mechanism to identify the parameter between the optimum current and the short current is discussed. A prototype of the controller has been set up and the experimental results have demonstrated excellent performance, proving the feasibility of the system. © 2002 Scripta Technica, Electr Eng Jpn, 139(1): 65–72, 2002; DOI 10.1002/eej.1147     

Seismic proof test of a reinforced concrete containment vessel (RCCV): Part 1: Test model and pressure test

In Japan, the Nuclear Power Engineering Corporation (NUPEC), sponsored by the Ministry of Economy, Trade and Industry (METI), has been conducting a series of seismic reliability proving tests using full-scale or close to full-scale models to simulate actual important equipment that is critical for seismic safety of nuclear power plants. The tests are intended to validate the seismic design and reliability with a sufficient margin even under destructive earthquakes. A series of tests was carried out on a reinforced concrete containment vessel (RCCV) for advanced boiling water reactor (ABWR) from 1992 to 1999. A large-scale high-performance shaking table at Tadotsu Engineering Laboratory, the largest in the world, was used for this test. Part 1 reports the test model and the results of pressure and leak tests. Part 2 describes test procedures, input waves and the results of verification tests such as changes of stiffness, characteristic frequency and damping ratio, the failure of the model and the load deflection. Part 3 shows the seismic safety margin that was evaluated from the energy input during the failure test to a design basis earthquake. Part 4 reports simulation analysis results by a stick model with lumped masses.