船用柴油机NOx等有害排放气体的评价及处理研究--燃料喷射系统对乳化燃料在船用柴油机上使用的影响及脱硝装置的适用性

对原试验用柴油机的燃料喷射系统进行了改造。改造后的燃料喷射系统不仅可降低 NOx 的排放 ,而且使高加水率乳化燃料的使用成为可能。但另一方面 ,在低负荷时 ,使用乳化燃料不但不能获得预期的降低 NOx 排放效果 ,反而使其它有害排放增加。所以 ,也对降低 NOx 排放方法之一的脱硝装置进行了探讨 ,对其在船用柴油机上的适用性进行了试验 ,并获得了较好的效果     

Development of Reference Shunt for Short‐Time Alternating High Current Tests and Study of Measuring System

Short‐circuit tests for power circuit breakers and others require alternative short‐time current measurement, from a few kA to over several tens kA. However, the reference measurement system as a national standard or a specified secondary standard instrument to directly perform comparative test as a complete calibration test in high current class has not yet been established globally. The Japan Short‐Circuit Testing Committee (hereinafter referred to as “JSTC”) has therefore developed a shunt resistor that can be used as a standard instrument for high current measurement. Reference system using this shunt resistor is also considered by JSTC. The performance of the newly developed shunt resistor has been checked through several methods, such as resistance measurement, high power current test, high frequency current test, temperature rise test, and interference test. The results of the tests proved satisfactory performance. Resistance of the shunt resistor before and after the tests was invariant and stable. This makes the shunt resistor adequate for a reference in practical use. In addition, evaluation of uncertainty of the whole reference system including this shunt resistor satisfactorily fulfills the requirements of IEC 62475 edition 1.0, 2010.     

A dynamical existence problem of macroeconomic policy model

The paper presents a procedure for the construction of a minimal dimension stato-spaeo representation for macroeconomic policy model. By using the results obtained here, the present paper clarifies the relationships among the minimal realization of the model, the basic concepts of controllability and observability, and dynamic policy existence. Thus, the paper shows a dynamic generalization of Tinbergen's theory of policy formation.     

电磁搅拌下低合金钢柱状晶向等轴晶转变准则(二)

在枝晶破碎理论基础上,讨论了电磁搅拌强度及合金元素碳、锰含量对钢凝固组织的影响。分析并获得了线性电磁搅拌下柱状晶向等轴晶转变(CET)的准则。观察到凝固过程中电磁搅拌产生的枝晶碎片,得到了临界固相分率、碳含量和液体平均流速之间的关系。发现低碳情况下,锰含量提高使CET更难;高碳情况下,锰含量提高对CET几乎没影响。     

Effects of annealing and quenching on fatigue behaviour in type 444 ferritic stainless steel

In order to understand the effects of annealing and quenching on fatigue behaviour in type 444 stainless steel, fully reversed axial fatigue tests have been performed using smooth specimens of heat‐treated materials in laboratory air and 3%NaCl aqueous solution. Three materials subjected to different heat treatments, annealing at 960 and 1000 °C, and water‐cooling at 960 °C, were prepared. In laboratory air, the fatigue limit of the annealed specimens was lower than that of the as‐received specimen and decreased with increasing annealing temperature. The subsequent grain coarsening from the heat treatments was primarily responsible for the lower fatigue strength in the annealed specimens. The fatigue strength of the water‐cooled specimen was lower than that of the corresponding annealed specimen. In the annealed specimens, cracks were generated within ferritic grains, while in the water‐cooled specimen, at or near grain boundaries. In 3%NaCl solution, the fatigue strengths of all specimens decreased compared with those in laboratory air. Only in the water‐cooled specimens, crack initiation at grain boundary and intergranular crack growth were observed, indicating the most sensitive to corrosion environment.     

Grinding of Si3N4 Ceramic Balls with the Aid of Photo-Catalyst of TiO2

There are big needs from industry that the polishing process using loose abrasive be replaced by grinding process. This paper explores the possibility of replacement by investigating effects of the free radical reaction on the precision grinding performance. Free radicals were generated with the aid of TiO₂, a kind of photo-catalyst. Experiments were conducted on Si₃N₄ ceramic ball grinding with a metal bonded diamond wheel of SD8000 and SD16000. It is found that, for SD8000, the material removal rate increases by a factor of about 6 when adding 7.5 wt% of TiO₂ into grinding fluid. Ion exchanged water was used in this experiment. This increase in the material removal rate is expected to be due to the dressing effect of the free radicals of H and HO₂ in water, which are both very strong oxidizing agents. The free radicals of H and HO₂ are generated in the photocatalytic reaction process of TiO₂ with water and oxygen under ultraviolet rays. For SD16000 only adding 1 wt% of TiO₂ leads to a dramatic increase in material removal rate from 0.08 μm/hr to 0.55 μm/hr.     

Cholesterol Lowering Activity of Ropy Fermented Milk

The effect of ropy fermented milk on serum cholesterol in rats was studied. Basic diets containing slime-forming Lactococcus lactis subsp. cremoris SBT 0495, its non slime-forming variant SBT 1275, and acidified reconstituted skim milk, with 0.5% cholesterol added, were fed to F-344 rats for 7 days. Serum cholesterol level of rats fed the ropy fermented milk were the lowest among the three treatments. The serum high-density lipoprotein (HDL) cholesterol/total cholesterol ratio of rats fed ropy fermented milk was the highest. Slime materials produced by L. lactis subsp. cremoris SBT 0495 had a beneficial effect on rat cholesterol metabolism.     

Anomalous X-ray Line Broadening Observed in γ-Fe2O3 Derived from γ-FeOOH

Defect structure of fine-grained γ-Fe₂O₃ powder obtained by dehydroxylation of y-FeOOH powder has been studied by X-ray diffraction and high-resolution electron micrographs. An anomalous X-ray line broadening was observed in the γ-Fe₂O₃ powder. It is found that the X-ray line breadth is dependent on the crystal structure factors of each reflection line: the reflections from net planes consisting of only metal ions on tetrahedral sites and octahedral sites of spinel structure are much broader than those from net planes including oxygen ions. The anomalous X-ray line broadening is explained on the basis of stacking faults in the spinel structure.     

Morphology of step-wise S–N curves depending on work-hardened layer and humidity in a high-strength steel

The present paper describes the effects of work‐hardened layer and humidity on the fatigue response of high strength steel, JIS SNCM439 (AISI4340). Tests were conducted in laboratory air and in dry air using cantilever‐type rotating bending fatigue testing machines. The dew point of dry air was ?60 °C. Specimens with two different surface conditions were prepared, i.e., buff‐finished and electro‐polished specimens. In the buff‐finished specimens, a stepwise S–N curve was seen in both environments, but the transition stress below which subsurface crack initiation occurred shifted to a higher stress level in dry air than in laboratory air. In the electro‐polished specimens, stepwise S–N curve was not observed in laboratory air, but seen in dry air. At stress levels where cracks initiated at the surface, the fatigue lives of the electro‐polished specimens were shorter than those of the buff‐finished specimens. At stress levels where subsurface cracks initiated, the fatigue lives of both specimens were the same, irrespective of surface finishing condition and humidity.