船用发动机有害排放气体的评价及处理研究--燃料性质和输出轴扭矩变化对发动机排放特性的影响

为了评价船用发动机有害气体的排放,本文从燃料的性质着手,较为详细地对不同性质的１３种燃 料进行了研究,并在一台中型四冲程船用柴油机上进行了试验,测定了各种有害排气的浓度、发动机的 性能和燃烧特性,对燃料的性质与排放之间的相关性进行了探讨。进一步调查研究了柴油机运转工况的 不同及输出轴扭矩的变化对ＮＯｘ排放的影响。由试验结果可知：对于周期性输出扭矩的变化,ＮＯｘ的排 放也发生周期性的变化。但是,柴油机在高输出区域运转时,随着扭矩增加所换算的ＮＯｘ浓度呈减小的 趋势;反之,在低输出区域运转时,呈增加的趋势;输出扭矩周期性变化时的ＮＯｘ。的浓度可以用与其相 对应的平均负荷状态的ＮＯｘ浓度处理。     

Progress of fluoropolymers on coating applications: Development of mineral spirit soluble polymer and aqueous dispersion

Fluoro-olefine vinyl ether copolymer (FEVE) has been well known as highly durable polymer for paints industry. FEVE has been widely used for ambient temperature curable solvent-borne paints. In this report, recent developments of FEVE copolymer are reported for mild-solvent paint system and water-borne paint system. Firstly, mineral spirit soluble FEVE copolymers are mentioned for both 1-component and crosslinkable 2-component mild-solvent paint systems. Secondly, FEVE aqueous dispersion polymers are mentioned for non-crosslinkable 1-component latex paint system, crosslinkable 2-component emulsion paint system with isocyanate as containing high OH value and for 1-component crosslinkable emulsion paint system containing carboxyl functionality reactive with hydrazide.     

用原子显微镜纳米压痕法研究Gr／Al复合材料热循环后的微观力学性能

采用原子力显微镜纳米压痕法测量了Gr/Al复合材料热循环后界面附近的纳米硬度和塑性变形能力的分布。随热循环次数的增加,纤维和基体中的纳米硬度小,而基体的塑性变形能力增加。纳米硬度和塑性变形能力的大小是随距纤维／基体界面的距离的变化而变化的。纳米硬度的变化可提供有关残余应变方面的信息,这是因为材料内部局部区域的弹性或塑性残余应变会影响此处的硬度大小。     

An adaptive method for the determination of the order of element for acquiring the desired accuracy in 3D elastostatic FEM analysis

An adaptive method for the determination of the order of element (or element order) was developed for the finite element analysis of 3D elastostatic problems. Here the order of element means the order of polynomial function, which interpolates the displacement distribution in the element. This method was based on acquiring the desired accuracy for each finite element. From the numerical experiments, the relationship ξ=k(1/p)^β was deduced, where ξ is the error of the result of the finite element analysis relative to the exact value, p is the order of element, and k and β are constants. Applying this relationship to the two results of computations with different orders of element, the order of element for the third computation was deduced. A computer program using this adaptive determination method for the order of element was developed and applied to several 3D elastostatic problems of various shapes. The usefulness of the method was illustrated by these application results.     

Prediction of gas‐liquid two‐phase mixture flow in a vertical pipe with a sudden expansion in diameter

The principle of gas‐lift pumps is applied to vacuum‐decarburization with the RH (Ruhrstahl Heraeus) process to circulate molten steel. Gas‐lift pumps are also applicable to the transportation of molten iron/steel between different refining processes. This paper treats theoretical analysis of steady‐state flow characteristics of gas‐liquid two‐phase mixtures rising in a vertical pipe with an abrupt expansion of its diameter. The system of governing equations is based upon a one‐dimensional multi‐fluid model. Flow pattern transitions are taken into consideration. A new numerical procedure to predict the flow characteristics at the sudden expansion has been proposed. Experiments have also been performed for several conditions to confirm the applicability as well as the validity of the present numerical model. It has been found that the predictions agree reasonably well with the experimental data. Next, the effect of the sudden expansion of pipe diameter on the pump performance was investigated numerically. As a result, it has been confirmed that the sudden expansion of pipe diameter contributes to improve the pump efficiency.     

Genome Maintenance Mechanisms at the Chromatin Level

Genome integrity is constantly threatened by internal and external stressors, in both animals and plants. As plants are sessile, a variety of environment stressors can damage their DNA. In the nucleus, DNA twines around histone proteins to form the higher-order structure “chromatin”. Unraveling how chromatin transforms on sensing genotoxic stress is, thus, key to understanding plant strategies to cope with fluctuating environments. In recent years, accumulating evidence in plant research has suggested that chromatin plays a crucial role in protecting DNA from genotoxic stress in three ways: (1) changes in chromatin modifications around damaged sites enhance DNA repair by providing a scaffold and/or easy access to DNA repair machinery; (2) DNA damage triggers genome-wide alterations in chromatin modifications, globally modulating gene expression required for DNA damage response, such as stem cell death, cell-cycle arrest, and an early onset of endoreplication; and (3) condensed chromatin functions as a physical barrier against genotoxic stressors to protect DNA. In this review, we highlight the chromatin-level control of genome stability and compare the regulatory systems in plants and animals to find out unique mechanisms maintaining genome integrity under genotoxic stress.     

Phase separation of phenolic resins 2. The fractionation of phenol-formaldehyde resin based on molecular weight and structure

The phase separation and fractionation for phenol-formaldehyde resins of the random novolak type (r-NR) were investigated by using r-NR/acetone/hexane and r-NR/acetone/cyclohexane ternary systems. The fractionation efficiency was elucidated by the partition coefficient, σ, which was derived from the theory of Flory and Huggins. The fractionation based on molecular structure and molecular weight occurred at the same time. The partition coefficient represented the fractionation efficiency based on molecular weight as well as on molecular structure. Received: 15 October 1997/Revised version: 14 November 1997/Accepted: 17 November 1997     

Promotional effect of H2O on the activity of In2O3‐doped Ga2O3–Al2O3 for the selective reduction of nitrogen monoxide

Effect of metal oxide additives on the catalytic performance of Ga₂O₃–Al₂O₃ prepared by the sol–gel method for the selective reduction of NO with propene in the presence of oxygen was studied. Of several metal oxide additives, the addition of In₂O₃ enhanced drastically the activity of Ga₂O₃–Al₂O₃ for NO reduction by propene in the presence of H₂O. In addition, the activity of In₂O₃‐doped Ga₂O₃–Al₂O₃ catalyst was extremely intensified by the presence of H₂O below 350°C. The promotional effect of H₂O was interpreted by the suppression of undesirable propene oxidation and the removal of carbonaceous materials deposited on the catalyst surface. We also found that close interaction of In₂O₃ and Ga₂O₃ is necessary for the enhancement of activity by H₂O. A lot of hydrocarbons except methane and oxygenated compounds served as good reducing agents, among which propene and 2‐propanol were the most efficient ones. In₂O₃‐doped Ga₂O₃–Al₂O₃ catalyst was capable of reducing NO into N₂ quite efficiently in the presence of H₂O at a very high space velocity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Enhancing low-temperature energy harvesting by lead-free ferroelectric Ba(Zr0.1Ti0.9)O3

The energy-harvesting ability of the lead-free ferroelectric Ba(Zr,Ti)O₃ was investigated and greatly enhanced using the Kim novel electrothermodynamic cycle for low-temperature application. Ba(Zr,Ti)O₃ was synthesized with a Zr:Ti ratio of 10:90 (BZT10) by hot-press sintering, which exhibited a mix relaxor-ferroelectric behavior. For power generation using the Kim cycle with low and high temperatures of T_L = 25°C, T_H = 120°C, the most optimized temperature pattern occurred for a heating time of 12.5 s and a cooling time of 22.5 s. Under these conditions, the electric field increased during the novel isodisplacement process, and the displacement variation in the isoelectric step reached the highest value and maximized the BZT10 cycle loop area. Applying these conditions while lowering T_L to 20°C, an energy density N_D = 504 mJ/cm³ was achieved. This value is the highest obtained energy density in a practical test for lead-free ferroelectric bulk material in the BaTiO₃ family.     

Hardenability Improvement Mechanisms and Hardenability-Controlling Factors in Steels With Combined Mo–B Addition

Metallurgical and Materials Transactions A - To elucidate the hardenability improvement mechanisms and hardenability-controlling factors in low-carbon (C) steels with the combined addition of...