Some statistical aspects of magnetization processes in ferromagnetic bodies. Motion of a single 180° Bloch wall in an imperfect crystalline medium

The ideally simple situation of a single 180° Bloch wall in a single crystal already involves rather complex physical mechanisms. For a given variation of the magnetic field, two types of irreversible motion of the wall can be observed, depending on the velocity imposed to the wall and the temperature. It can move like a rigid plane, then its irreversible displacements are always larger than its thikness. It can also move by localized, small jumps thanks to its internal degrees of freedom. The features of the Barkhausen noise are different in these two kinds of motion. The transition between them occurs either at a constant temperature by increasing the velocity of the wall, or at a constant velocity by lowering the temperature. The wall can also move under the effect of thermal fluctuation, which should not be regarded as some little perturbation, but rather as an essential physical parameter which has to be taken into account in any realistic model of wall motion, and hence of “Barkhausen noise”. The random character of these phenomena allowed us to employ simple, but very useful, statistical methods. Besides, this study suggests some specific problems of “signal processing”.     

Wall and ceiling protection for heating appliances

An evaluation was made of the effects of radiant heat transfer from hot stove and chimney pipes to unprotected and protected room walls and ceilings. Pipe surface temperatures were 350° C (662° F) for normal operation, and 400–450° C (752–842° F) to simulate overfire conditions. Unprotected ceilings at 457 mm (18 in.) clearance met code recommended temperature rise limits for normal operation, but protection was needed for overfire exposures. Some protected walls allowed for clearance reductions to 76 mm (3 in.) for all exposures, while others needed at least 304 mm (12 in.) for normal and 457 mm (18 in.) for overfire exposures.Recommendations for model building code specifications for wall and ceiling protection are provided. Reference: Joseph J. Loftus and Richard D. Peacock, Wall and Ceiling Protection for Heating Appliances,Fire Technology, Vol. 21, No. 3, August 1985, p. 213.This paper is a contribution of the National Bureau of Standards and is not subject to copyright.     

基坑支护优化设计的数学模型研究

基坑支护设计属于系统工程设计,包括方案设计和细部结构设计两个层次,相应地,基坑支护设计变量具有层次性、结构性和不确定性．对此,提出了基于搜索的基坑支护协同优化设计分析模型,给出了与方案、细部和子细部优化相对应的数学模型,并讨论了总系统优化与各子系统优化即全局寻优与局部寻优的关系,得出“必须求解能全面反映各子系统间各种耦合关系的总系统才能得到基坑支护系统的全局最优解”的结论。     

浅谈住宅一户一表生活给水的设置

随着商品经济的发展,各户轮值抄表计费方式越来越不被民众所接受,"一户一表"是民心所归,是自来水收费体制上的一次重要改革,势在必行.详细地介绍了"一户一表"设置的几种方法和表位设置的形式,并对其发展趋势及方向作了详尽地分析,指出"一户一表"的设置必将沿着外墙式、水表间式表位设置,最终向IC卡(TM卡)式、远传水表电脑计量收费方式发展.文中还对"一户一表"的水力计算进行了分析,提出了"一户一表"设置的水力条件.     

The cell wall sensor Wsc1p is involved in reorganization of actin cytoskeleton in response to hypo-osmotic shock in Saccharomyces cerevisiae

The cell wall is essential to preserve osmotic integrity of yeast cells. Some phenotypic traits of cell wall mutants suggest that, as a result of a weakening of the cell wall, hypo-osmotic stress-like conditions are created. Consequent expansion of the cell wall and stretching of the plasma membrane trigger a complex response to prevent cell lysis. In this work we examined two conditions that generate a cell wall and membrane stress: one is represented by the cell wall mutant gas1Delta and the other by a hypo-osmotic shock. We examined the actin cytoskeleton and the role of the cell wall sensors Wsc1p and Mid2p in these stress conditions. In the gas1 null mutant cells, which lack a beta(1,3)-glucanosyltransferase activity required for cell wall assembly, a constitutive marked depolarization of actin cytoskeleton was found. In a hypo-osmotic shock wild-type cells showed a transient depolarization of actin cytoskeleton. The percentage of depolarized cells was maximal at 30 min after the shift and then progressively decreased until cells reached a new steady-state condition. The maximal response was proportional to the magnitude of the difference in the external osmolarity before and after the shift within a given range of osmolarities. Loss of Wsc1p specifically delayed the repolarization of the actin cytoskeleton, whereas Wsc1p and Mid2p were essential for the maintenance of cell integrity in gas1Delta cells. The control of actin cytoskeleton is an important element in the context of the compensatory response to cell wall weakening. Wsc1p appears to be an important regulator of the actin network rearrangements in conditions of cell wall expansion and membrane stretching.     

Higher intake of DK265 corn silage by dairy cattle

In this experiment, intake of DK265 3-way corn hybrid by dairy cattle was compared specifically with intake 1) of its bm3 isogenic form, 2) of its 2 related single-way hybrids, and 3) of 2 controls that were registered hybrids of similar earliness. Both dry matter (DM) and lignin contents were similar in all hybrids except for the bm3 hybrid, which was less lignified. There was a tendency for lower starch content and, correlatively, higher neutral detergent fiber content in DK265 and in the 2 related single-way hybrids. Significant intake differences were observed between hybrids; the highest intake was recorded for the bm3 hybrid. Among normal hybrids, DK265 and one of its related single-way hybrids registered significantly higher intakes than other hybrids. Among normal hybrids, cell wall digestibility and/or lignin content did not explain all of the variations observed for intake, whereas the higher intake of DK265 bm3 could be related to its lower lignin content as compared with isogenic DK265. It was hypothesized that the higher intake observed for the DK265 hybrid was probably related to specific friability traits that are not relevantly measured through the usual tests used in corn breeding.     

刚体位移测量的数字散斑相关法的研究

结合计算机辅助测试CAT和虚拟仪器技术,阐述了数字散斑相关方法DSCM(Digital Speckle Correlation Method)测量刚体位移的理论与过程。同时针对求解三参数相关系数最大值点提出了一种“编程简单、时间节省、精度良好”的实用新算法,即“正方体爬山搜索法”。并利用仿真实验进行了成功验证,仿真实验效果非常理想,测量值与给定理论值相比很接近,计算速度也比较快。     

逆作法施工中节点的处理及质量控制

结合工程实例,介绍深基础逆作法施工中地下结构的梁、板、墙与地下连续墙连接节点的具体做法及质量控制。     

聚氨酯硬泡在防撬门生产中的应用

论述了硬质聚氨酯泡沫塑料作为防撬门内部填充材料的生产工艺及其优越性,指出前发泡、后静电喷涂面漆的工艺虽然优于后发泡工艺,但是必须选用开孔聚氨酯硬泡才能解决高温膨胀问题,并提出使用聚氨酯预制件代替金属材料密封门体内部活动件的可行性。