Enantioselective Reaction of Imines and Benzyl Nitriles Using Palladium Pincer Complexes with C2‐Symmetric Chiral Bis(imidazoline)s

Enantioselective reactions of a wide variety of benzyl nitriles with N‐tosylimines catalyzed by novel chiral 1,3‐bis(imidazolin‐2‐yl)benzene‐palladium(II) [Phebim‐Pd(II)] complexes have afforded the respective products in high yield with good enantioselectivity. A reaction mechanism is proposed based on X‐ray crystal structures of palladium complexes.     

Model-based reconstruction integrated with fluence compensation for photoacoustic tomography

Photoacoustic (PA) tomography (PAT) is a rapidly developing imaging modality that can provide high contrast and spatial-resolution images of light-absorption distribution in tissue. However, reconstruction of the absorption distribution is affected by nonuniform light fluence. This paper introduces a reconstruction method for reducing amplification of noise and artifacts in low-fluence regions. In this method, fluence compensation is integrated into model-based reconstruction, and the absorption distribution is iteratively updated. At each iteration, we calculate the residual between detected PA signals and the signals computed by a forward model using the initial pressure, which is the product of estimated voxel value and light fluence. By minimizing the residual, the reconstructed values converge to the true absorption distribution. In addition, we developed a matrix compression method for reducing memory requirements and accelerating reconstruction speed. The results of simulation and phantom experiments indicate that the proposed method provides a better contrast-to-noise ratio (CNR) in low-fluence regions. We expect that the capability of increasing imaging depth will broaden the clinical applications of PAT.     

Evaluation of C02 Reduction and Primary Energy Savings for Collective Housing with Fuel Cells Considering Variability in Demand

In Japan, residential FCs （fuel cells） are being introduced not only in detached houses but also in collective housing. In this context, the effects of FC introduction （e.g., primary energy savings） should be quantitatively evaluated, but this has not been done sufficiently for collective housing, particularly with regard to demand variability. Here, the authors propose a method taking into account demand variability to evaluate the effects of FC introduction into collective housing, based on a finite set of observational demand data. The method provides a new viewpoint for evaluating the effects of FC introduction. Numerical simulation results based on real-world data indicate the validity of these effects in terms of primary energy savings and CO2 reduction considering demand variability.     

Active chatter suppression in turning by band-limited force control

The suppression of chatter vibration is required to enhance the machined surface quality and to increase tool life. In this study, a new, conceptually active approach for chatter suppression in machining is proposed. The hybrid control method developed by applying sensorless force control with a disturbance observer enables the simultaneous and independent control of the position trajectory and band-limited forces. The proposed method is introduced to the carriage of a prototype desktop-sized turning machine, and the ability to suppress chatter is evaluated by end-face cutting tests. The results demonstrate that actively controlling a band-limited force leads to the avoidance of chatter.     

Verification of effect of damper windings on the transient condition of synchronous generator

This paper describes the results of an experimental investigation on the effects of the damper winding of a four‐pole synchronous generator at a synchronous generator transient. It is known from simulations that the damper winding acts effectively under synchronous generator transient conditions. However, experimental proof has not been obtained yet. Thus, experiments on damper effects were conducted using a laboratory‐scale power system. The damper winding of the tested generator consisted of five damper bars for each pole; the number of working damper bars could be changed manually. The damper currents at each bar were measured by a Rogowski coil. FFT analysis was applied to both the damper currents and armature currents under different operating conditions. The relationships between damper currents in the rotor and armature currents in the stator were made clearer than before. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(2): 33–42, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21278     

Advanced Reactive Power Control at Individual Residences to Smooth Energy Loss Fluctuation for a Clustered Grid-Interconnected PV System

Reactive power control can control voltage within the proper range from the power network side or from the distribution generation （PV （photovoltaic）） side. Reactive power control from the power network side is simpler because little controlled object apparatus, such as STATCOM, is required. However, it is difficult to optimize the individual voltages of residential consumers because few data have been obtained by the power network side as compared with the power generation side. Energy loss at each residence with PV is different due to the difference in the grid-interconnection condition, such as distribution line impedance when the same operating voltage is set at all residences. Therefore, in this paper, the authors propose an advanced reactive power control method for residential PV systems in order to optimally control the voltage at individual residences so as to minimize energy loss fluctuation. The effectiveness of the proposed reactive power control is demonstrated by numerical simulation.     

THERMAL SHOCK PROBLEMS OF ELASTIC BODIES WITH A CRACK

This paper deals with thermal shock, problems of elastic bodies with a crack. The case considered is that of an infinitely long circular cylinder with an edge crack, and a homogeneous flat plate with an edge crack initially at uniform temperature and suddenly immersed into a medium of lower temperature. The thermal disturbance near the crack tip is assumed to be neglible in the analysis of the temperature field because thermal shocks occur very quickly. We analyze the transient thermal stress problems of elastic solids with a crack and determine the stress intensity factor at the crack tip. The nondimensional maximum transient stress intensity factor is expressed as a function of the Biot number and the nondimensional crack length. Then we propose simplified formulations of the nondimensional maximum transient stress intensity factor as a function of the Biot number and the nondimensional crack length.     

Cross section adjustment method based on random sampling technique

A cross section adjustment method based on the random sampling technique is proposed. In the proposed method, correlations among cross sections and core parameters are used instead of sensitivity coefficients of cross sections, which are necessary in the conventional method. The correlations are statistically estimated by the random sampling technique. The proposed method is theoretically consistent with the conventional method and provides comparable adjusted cross sections when sufficient number of random sampling is taken into account. The proposed method would be suitable for practical light water reactor (LWR) core analysis since estimation of sensitivity coefficients, which requires considerable computational cost in typical LWR problems, is not necessary. Through a benchmark problem in simple pin-cell geometry, adjusted cross sections by the present and the conventional cross section adjustment method are compared. The adjusted cross sections by the present method well reproduce the conventional ones, thus the feasibility of the present method is confirmed.     

Stress and strain measurements in carbon-related materials impacted by a high-velocity steel sphere

To investigate the behavior of carbon-related materials damaged by the impact of a sphere, stress and strain measurements during the impact were carried out using a PVDF stress gauge and a constantan strain gauge. A spherical projectile having a velocity of ca. 150–1300 m/s was allowed to impact carbon fiber-reinforced plastics (CFRPs) with different carbon fibers, CFRPs with and without surface-treated fibers, polycrystalline graphites and a C/C composite. The maximum stress generated in the CFRPs depended on the reinforcing fibers; pitch-based fiber resulted in larger increase in stress with impact velocity. The CFRP without the surface-treated fiber resulted in lower strain and stress than the CFRP consisting of the surface-treated fiber. Polycrystalline graphites showed a very large strain, and then powdering; the movement of the powder was considered to affect stress and strain in the graphite materials.     

Thermoelectric Efficiency of Reduced SrTiO3 Ceramics Modified with La and Nb

Ceramics of La_xSr_1?xNb_yTi_1?yO₃ (LSNT) were synthesized under various reducing atmospheres. Covering the specimens with graphite carbon felt under an Ar‐gas flow during sintering drastically enhanced the electrical conductivity, σ. Ti K‐edge absorption spectra indicated the presence of Ti³⁺ for heavily reduced specimens. The increase in conductivity was attributed to the 3d band of Ti³⁺. The maximum value for the figure of merit, ZT, was obtained for strontium titanate ceramics modified with both 5 mol% La and 5 mol% Nb, namely 5/5‐LSNT, exhibiting a ZT value of ~0.221 at 473 K. This high ZT value was almost 1.5 × larger than that of the conventional 10 mol% La‐doped sample, 10/0‐LSNT (ZT~0.144), and was mainly attributed to the larger Seebeck coefficient of the material.