Chemical Processing and Properties of (Sr,Ca) 2 (Nb,Ta) 2 O 7 Thin Films

Ca-doped Sr 2 (Nb,Ta) 2 O 7 thin films have been synthesized by the chemical solution deposition. Homogeneous and stable (Sr,Ca) 2 (Nb,Ta) 2 O 7 precursor solutions were prepared by optimizing the reaction of starting metal alkoxides in ethanol with a key additive of 2-ethoxyethanol. The improvement of ferroelectric properties of the Sr 2 (Nb,Ta) 2 O 7 based films were achieved through the Ca substitution into Sr 2 (Nb 0.3 Ta 0.7 ) 2 O 7 as well as the optimization of heating conditions. The crystallization temperature of the layered perovskite (Sr 0.9 Ca 0.1 ) 2 (Nb 0.3 Ta 0.7 ) 2 O 7 thin films on Pt/Ir/Ti/SiO 2 /Si substrates was found to be above 750C. (Sr 0.9 Ca 0.1 ) 2 (Nb 0.3 Ta 0.7 ) 2 O 7 thin films crystallized at 750C exhibited P r of 0.51 w C/cm 2 and E c of 69 kV/cm.     

A field study of lightning overvoltages in low‐voltage distribution lines

The number of home electric appliances, such as personal computers and telephones, has been rapidly increasing. Lightning damage to these home electric appliances has a great impact on a highly sophisticated information society. There are cases in which lightning overvoltages in low‐voltage distribution lines cause malfunctions in them, even though they are equipped with surge protective devices to protect against lightning overvoltages. Therefore, for lightning protection of low‐voltage equipment including home electric appliances, it is important to understand the phenomenon of lightning overvoltages in low‐voltage power distribution lines. However, many aspects of this problem are not entirely clear, in particular how they are generated. The Tokyo Electric Power Company carried out lightning observations on low‐voltage distribution lines. The observation results provide a statistical distribution of lightning overvoltages in low‐voltage distribution lines. A mechanism for generating lightning overvoltages in low‐voltage distribution lines is inferred from the observed waveforms and facilities data. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 12–21, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21299     

Reaction layer formation on bronze with an S-P extreme pressure additive in boundary lubrication under increasing load: I

An extreme pressure film formed on a phosphor bronze sliding against hardened ball-bearing steel with an S-P compound in mineral oil was examined. Film formation under boundary lubrication with continuously increasing load was observed using surface analytical methods. The concentration of tin in the reaction layer was found to be more enhanced than that of other elements. The segregation of phosphorus and tin showed good correlation but the sulphur distribution in the film was distinctly different. The film formed was often thick, up to 20 μm. Such a film had poor lubricity and weak strength against shearing.     

A successful surgical repair of ventricular septal perforation, whose perforated position could be marked by Swan-Ganz catheter before the operation

The patient was a 72-year-old woman who was admitted with AMI. On the next day, a systolic murmur of Levine II/VI became audible on the left sternal border of the 5th intercostal space and VSP was diagnosed by the echocardiogram. The hemodynamics was comparatively stable, and so we scheduled the elective operation in the expectation of the healing of the infarction tissue. At the cardiac catheterization just before the operation, L-R shunt ratio was 64.9% and main PA was 41/18 (26) mmHg. Before the operation we marked the VSP position by Swan-Ganz catheter through the left ventricle and VSP closure and 2 CABG was performed. We concluded that this method was useful for the diagnosis and therapy of VSP.     

Conversion factors for a mobile survey method by car in the Chernobyl area

Conversion factors for the purpose of mobile survey by car in the Chernobyl area have been evaluated using simulation calculations. In the calculations, the width of road is assumed as being 4 m, 10 m and 20 m and the surrounding area is divided into ten zones contaminated homogeneously by 137Cs with different depth profiles in the ground. The air kerma contribution from all zones to the road is simulated. A conversion factor is calculated by dividing the air kerma rate in typical land-use adjacent to the road by that on the road. Conversion factors in various land uses around the roads are examined. The calculated conversion factors agree with the conversion factors measured in the Chernobyl area within an accuracy of 20%. Further, basic data, needed for composing conversion factors appropriate to other contaminated regions with different depth distributions from the Chernobyl area, are also indicated.     

Isthmic afferent neurons identified by the retrograde HRP method in a teleost, Navodon modestus

Isthmic afferent neurons were investigated by the retrograde horseradish peroxidase (HRP) method in a teleost, Navodon modestus. Following HRP injections into the nucleus isthmi, large pyriform neurons are labeled in the ipsilateral optic tectum. Very large and multipolar neurons are also labeled in the ipsilateral nucleus pretectalis. No labeled neurons were found in other areas.     

Thermal stability of Si/Gen/Si heterostructures by photoreflectance

The thermal stability of Si/Ge_n/Si(001) heterostructures includingn = 1, 6, 20, and 100 monolayers (ML’s) is studied in connection with their electronic structures through the measurement of photoreflectance (PR). The PR spectra are observed at 90 K over the energy range 0.85–4.0 eV. Comparing the PR signals of Si/Ge _n /Si(001) heterostructures before and after thermal annealing at 600° C, it is found that the samples with less than 6 ML Ge show no change whereas those with more than 20 ML Ge show large changes. The result suggests that Si/Ge _n /Si heterostructures with Ge layer thickness less than 6 ML’s are thermally stable. For the heterostructures with 20 and 100 ML Ge, the relaxation of strain in the Ge layer is found to occur from the PR spectra ofE ₀(Ge),E ₁(Ge) andE ₁ +Δ ₁(Ge), andE ₁(Si).     

Polynomial Chaos Decomposition for the Simulation of Non-Gaussian Nonstationary Stochastic Processes

A method is developed for representing and synthesizing random processes that have been specified by their two-point correlation function and their nonstationary marginal probability density functions. The target process is represented as a polynomial transformation of an appropriate Gaussian process. The target correlation structure is decomposed according to the Karhunen–Loève expansion of the underlying Gaussian process. A sequence of polynomial transformations in this process is then used to match the one-point marginal probability density functions. The method results in a representation of a stochastic process that is particularly well suited for implementation with the spectral stochastic finite element method as well as for general purpose simulation of realizations of these processes.     

On the High-Speed Turn-Off of a Power Transistor by a Small Saturable Core

An effective method for reducing the size and weight of the switching dc-dc converter is to increase the switching frequency. To accomplish this with no deterioration in efficiency, it is necessary to suppress the switching loss per cycle by shortening the switching time. An efficient dc-dc converter operating at the megahertz region is presented. The turn-off time is shortened by using the current feedback and the core saturation. The turn-off mechanism is analyzed with the equivalent circuits. As a result, it is found that the excess carrier in the base region is discharged quickly by the large reverse base current, which flows when the energy stored in the base-emitter capacitance of the power transistor is transferred to the saturated inductance of the core with high frequency oscillation.