Preparation and Characterization of Machinable Mica Glass-Ceramics by the Sol-Gel Process

The preparation and characterization of machinable mica glass-ceramics by the sol-gel process are described. The thermal behavior of the precursor and the optimum conditions for calcination, molding, and sintering are given. Physical, chemical, thermal, electrical, and mechanical properties are investigated, and the machinability of the ceramics is discussed.     

Effect of Two-Step Heating on Gel Properties of a Paramyosin-Myosin System

The effect of two-step Heating, including low temperature setting, on the gel properties of the paramyosin-myosin system was investigated. At relatively low paramyosin contents, little effect of the two-step heating on gel properties was observed. When the paramyosin became 25 % or more, the indices of gel properties became significantly larger than those for the gels prepared by one-step heating. Paramyosin was more susceptible to the effect of two-step heating than myosin. It was thus concluded that paramyosin was mainly responsible for the effect of setting in invertebrate muscle gels.     

Empirical correlations for predicting the self-leveling behavior of debris bed

Studies on the self-leveling behavior of debris bed are crucial for the assessment of core-disruptive accident (CDA) occurred in sodium-cooled fast reactors (SFR). To clarify this behavior over a comparatively wider range of gas velocities, a series of experiments were performed by injecting nitrogen gas uniformly from a pool bottom. Current experiments were conducted in a cylindrical tank, in which water, nitrogen gas and different kinds of solid particles, simulate the coolant, vapor (generated by coolant boiling) and fuel debris, respectively. Based on the quantitative data obtained (mainly the time variation of bed inclination angle), with the help of dimensional analysis technique, a set of empirical correlations to predict the self-leveling development depending on particle size, particle density and gas injection velocity was proposed and discussed. It was seen that good agreement could be obtained between the calculated and experimental values. Rationality of the correlations was further confirmed through detailed analyses of the effects of experimental parameters such as particle size, particle density, gas flow rate and boiling mode. In order to facilitate future analyses and simulations of CDAs in SFRs, the obtained results in this work will be utilized for the validations of an advanced fast reactor safety analysis code.     

A Study on Influence of Ramp Event of Aggregated Power Output of Photovoltaic Power Generation on Electric Power System Frequency

This paper examines the influence of aggregated power output fluctuation of photovoltaic power generation system (PVS) on the power system frequency focusing on ramp events of aggregated PVS power output. A numerical simulation model of economic load dispatching control (EDC) and load frequency control (LFC) is used together with a PVS power output forecasting model and a unit commitment (UC) scheduling model developed in our preceding study. As a result, in the case of ramp event with long duration and high ramp rate, the frequency violation occurs when the power output of controllable generators with high load‐following capability reaches to upper/lower limit even if the power output of low load‐following capability generators is still available. If the load dispatching scheme is tentatively changed from the conventional EDC using an equal incremental fuel cost rule to, for example, a dispatching policy based on the capacity without the consideration of fuel cost, the aggregated load‐following capability can be kept, avoiding the frequency violation.     

Low damage lamella preparation of metallic materials by FIB processing with low acceleration voltage and a low incident angle Ar ion milling finish

Metallic materials are known to be very sensitive to Gallium (Ga) focused ion beam (FIB) processing. Crystal defects formed by FIB irradiation degrade the transmission electron microscope image quality, and it is difficult to distinguish original defects from FIB process-induced damage. A solution to this problem is the low acceleration voltage and low incident angle (LVLA) Argon ion milling, which can be incorporated as an extensional countermeasure for FIB damage removal and eventually for preparation of high-quality lamellae. The transmission electron microscope image quality of iron single crystal could be improved by removing crystal defects using the low acceleration voltage and low incident angle Argon ion milling finish. Lamella quality of the processing result was almost similar with that of the conventional electrolytic polishing. As a practical application of the process, low damage lamella of stainless cast steel could be prepared. Effectiveness of the FIB system equipped with the low acceleration voltage and low incident angle Argon ion milling function as a tool to make high-quality metallic material lamellae is illustrated.     

Spectral Variation of SKβ Emission with Sulfur Content in As-S Glasses

The bonding and chemical state of sulfur in binary As-S glasses were investigated by determining the S Kβ spectra with a vacuum 2-crystal X-ray spectrometer equipped with Ge(ll1) crystal analyzers. For glasses with sulfur contents <60 at.%, the spectra were similar to those of realgar (crystalline As₄S₄) and orpiment (crystalline As₂S₃); the profile of the SKβ spectrum did not change when half the sulfur was replaced by selenium. For sulfur contents > 60 at.%, the spectra became progressively similar to that of elemental sulfur with increasing sulfur content. It was found that S-S bonding occurs in the high-sulfur glasses.     

FACTORS AFFECTING THE VISCOELASTIC PROPERTIES OF ALBUMEN FOAMS1

The stability of foams prepared from egg albumen could be characterized by the changes in viscoelastic parameters obtained from measurements of stress relaxation and creep in compression. The initial relaxation modulus and instantaneous elasticity increased with time for about 40 min after the preparation of the foams because of the slow rate of adsorption of ovalbumin molecules to the air/water interface of the liquid film. These moduli then decreased with aging due to the thinning and rupture of the liquid films in the foam. The rate of decrease of the moduli was accelerated by reducing the concentration of sugar or by lowering pH in the aqueous phase of the liquid films. The presence of a certain amount of sugar seems to control the drainage rate of water from the liquid films, while the electrostatic repulsion between the inside surfaces of the liquid films may decrease in the acid region according to the reducing charged potential at the inside surfaces adsorbed ovalbumin molecules.     

旋转光栅调制傅里叶变换频谱仪

提出了一种基于圆盘旋转光栅调制的傅里叶变换光谱仪 (FTS) ,光栅同时实现了分束和外差调制的功能。分析了三种实现分光的方案 ,通过对三个波长分别为 670nm ,63 3nm和 5 3 2nm的激光进行了频谱测量实验 ,结果表明该光谱仪具有良好的稳定性和抗干扰能力 ,经调制后测量灵敏度倍增 2 0倍 ,尤其适用于微弱信号测量和近红外领域。     

PMSM Sensorless Control Based on Position Estimation Correction Using All‐Pass Filters

This paper proposes a novel flux estimation method for the position sensorless control of permanent magnet synchronous motors (PMSMs). In general, the stator flux linkage for position estimation in PMSMs is obtained using the pure integration of voltages. The infinite dc gain of the pure‐integrator, however, causes numerical drifts in the obtained stator flux linkage due to the dc offset in the input of this integrator. To address this problem, a quasi‐integrator is often substituted instead of the pure integrator to restrict the dc gain, leading to another problem in which the phase characteristics vary according to the operating frequency. As a result, the ideal phase characteristics (?90° constant) cannot be held, and the position estimation performance deteriorates. Therefore, this paper proposes a phase characteristic correction method for quasi‐integrators using all‐pass filters, which achieves extremely precise estimation under transient conditions as well as in steady state.     

Structural Optimization of Autonomous Energy Networks by Mathematical Programming Techniques

The renewal of conventional energy systems is important countermeasures against global warming effects and natural hazards. A self‐sustainable decentralized energy system is one of the promising solutions for future sustainable and resilient societies. In this paper, a mathematical programming model is formulated and design and utilization of the overall energy network is optimized based on the model, where stationary batteries are equipped. Through some numerical simulation results, the effectiveness and the potential, for example, for clarifying the effect of the batteries, of the proposed model are investigated.