也谈轻型钢结构房屋柱基设计

对柱脚抗剪键的设置和计算中所取用的荷载组合提出个人观点,同时对轻钢结构柱脚螺栓受拉计算提出注意事项.     

The transmission capacity of a nonlinear classical communication channel

The transmission capacity of a nonlinear classical communications channel that does not obey the well-known Shannon formula describing a linear additive channel is analyzed. According to the Landauer principle, no finite energy is required to transmit a bit of information, which, in principle, makes reversible data transmission possible. The process of data transmission is analyzed using a model of the transmitting medium representing a ferroelectric crystal possessing a center of symmetry. Using this model, it is possible to trace an analogy between the process of bit setting and transmission, on the one hand, and the violation of the lattice symmetry as a result of the second-order phase transition at the Curie temperature, on the other hand. An expression for the transmission capacity is obtained using the well-known cnoidal solution of the corresponding nonlinear equations in the absence of damping. The transmission capacity of an arbitrary nonlinear classical communication channel is estimated.     

Effect of the size of martensite laths and carbide particles on the “brittle” strength of low-carbon martensitic steels

Results of experimental and theoretical studies of the effect of the size of martensite laths and carbide particles on the value of the minimum stress of brittle fracture (brittle strength) of steel 12KhN3MFA subjected to uniaxial extension are presented. The critical proportion of the sizes of carbide particles and martensite laths is determined at which the microstructural component that controls the level of the brittle strength changes. Quantitative dependences for predicting the effect of the nonuniformity of the grain structure on the brittle strength of martensitic steels are obtained. Parameters of the microstructure, which make it possible to raise the brittle strength of low-carbon martensitic steels, are determined and the efficiency of rapid heat treatment for creating such structural states is demonstrated.     

现代主义空间的营造--丹·凯利的设计方法分析

丹·凯利的规则几何构图给他的作品赋予了鲜活的生命力,取得了非凡的效果.凯利的景观作品在平面上避免绝对的和谐,并且避免在景观的边缘以安静的方式结束,而是采用动态的方式,使其成为有活力的组成部分.我们把这种特征称作slippage,是对边缘的定义或是隐喻一种在平面和分区上有意不明确的设计方法.该文同时还把密斯的建筑作品和丹·凯利的作品进行对比,来发现二者在秩序和空间概念上的相同点和不同点,从而进一步探讨现代主义空间的构成.     

浅谈我国环境保护资金筹措

当前环境保护事业日益受到关注与重视,如何解决其投融资问题迫在眉睫。本文对我国目前的环保融资现状进行了分析,并对其发展提出了一些建议。     

Experimental study of the effect of external signal on microwave oscillations in a nonrelativistic electron beam with virtual cathode

The effect of an external harmonic signal on the characteristics of microwave generation in a non-relativistic electron beam with virtual cathode (VC) formed in a static retarding electric field (low-voltage vircator system) has been experimentally studied. A significant increase in the vircator generation power is observed when the frequency of the external signal is close to the frequency of VC oscillations. At large detunings, a broadband chaotic generation is observed.     

一种低压低功耗SRAM/SOI单元设计

提出一种改进4管自体偏压结构SRAM/SOI单元.基于TSUPREM4和MEDICI软件的模拟和结构性能的分析,设计单元结构并选取结构参数.该结构采用nMOS栅下的含p+埋沟的衬底体电阻代替传统6管CMOSSRAM单元中的pMOS元件,具有面积小、工艺简单的优点.该结构可以在0.5V的电源电压下正常工作,与6管单元相比,该单元瞬态响应正常,功耗只有6管单元的1/10,满足低压低功耗的要求.     

准噶尔盆地加快天然气勘探有利条件及预探领域分析

准噶尔盆地天然气资源十分丰富,勘探潜力巨大。该盆地具备形成大气区的地质背景,发育石炭系、二叠系、侏罗系三套气源岩,演化程度高,气源条件充足;发育多类型、多套储集体和四套区域盖层,形成了有利的储盖组合及成藏配置。通过对五彩湾、滴西、莫索湾、莫北地区典型气藏的分析研究,该盆地发育多种气藏类型,包括构造型、古潜山型、火山岩内幕型及地层(不整合遮挡)型。通过研究指出,天然气勘探的现实领域有陆东—五彩湾地区、陆西—莫北—莫索湾地区;待突破的领域有腹部下组合大型古隆起及岩性气藏、南缘冲断带;正在准备的勘探领域主要为煤层气。     

应用改进的BP神经网络预测导弹的研制费用

结合导弹武器系统研制的特点，分析并确定了影响导弹武器系统研制费用的主要因素，并在前人研究的基础上，提出了基于改进的BP神经网络的费用预测模型。该模型不仅克服了以往由于专家主观因素而造成的负面影响，而且提高了算法的运行效率和模型的预测精度。通过具体的实例分析比较，充分证明了利用该方法的科学合理性。最后探讨了利用BP神经网络进行数值预测的方法和应该注意的问题，并给出了一些有益的建议。     

正交试验在摩擦焊工艺参数优化中的应用

通过正交试验得出摩擦焊工艺参数中对接头抗拉强度的影响的顺序是摩擦压力、顶锻压力、摩擦时间。为在生产实际中制定摩擦焊接工艺规范提供了重要的参考依据。