风管摩擦阻力的直接计算方法

提出用高精度的反映密度、黏度和温度关系的经验公式和Colebrook公式计算风管摩擦阻力系数的方法。分析和算例表明，用该方法计算，计算结果比采用常用工程设计方法更为准确，为应用计算机进行风道设计提供了直接、简便的方法。     

不断创新管理机制努力做好学生工作

当我国的素质教育在知识经济崛起的世纪之交迅猛推进的时候,"如何才能全面有效地提高大学生的素质"就成为了教育者执着探询的重要课题.多年的教育实践使我们深深地认识到,全面推进素质教育就必须要坚持与时俱进,不断创新管理机制.具体来讲,就是要实施四个创新:     

在Fe-Al-C系统中合成优质Ⅱa型宝石级金刚石单晶

和优质Ib型宝石级金刚石单晶生长相比，作为当今高温高压晶体生长的一种高精尖技术，优质1／a型宝石级金刚石单晶对合成技术提出了更高更苛刻的要求：枢研究从晶体的生长速度出发，发现一开始阶段（大约几个小时）的晶体生长速度对优质宝石级金刚石单晶的后期生长争关重要。埘Fe-Al-C系统（Al含量不大于2．5wt％）来说，采用多品种法将晶体开始阶段的晶体生长速度由1．5mg／h降至0．5mg／h后，对生长过程中金属包裹体的进入有了明显的抑制作用，晶体的质量有了很大提高。从晶体中包裹体的存任形式来看，为了获得优质Ⅱa型宝石级金刚石单晶，在触媒中人为地添加除氮剂给晶体生长过程中的排杂过程带来了很大的难度：为了更好的实现排杂，必须很好的处理晶体表面的径向平铺生长速度和晶体轴向的堆积生长速度之间的火系。     

红外测温技术在离心复合铸造轧辊生产上的应用

本文分析了离心复合铸造轧辊生产过程中离心机停机温度和时间对轧辊质量的影响 ,提出了用先进的红外测温技术来预报停机温度和时间 ,以实现微机监控适时停机 ,保证轧辊内外层熔合良好 ;同时指出了红外测温技术在离心复合铸造轧辊生产上的应用前景     

氰化氢在终冷塔中气液两相之间转移的研究

分析了煤气中氰化氢的形成,论述了氰化氢在煤气和其冷凝液中的平衡机理,讨论了影响氰化氢相平衡的因素,研究了直接终冷、间接终冷时煤气中氰化氢的转移情况。     

A novel spherical-ordered macroporous CuO nanocatalyst for the electrochemical reduction of carbon dioxide

Journal of Applied Electrochemistry - The electrocatalytic reduction of CO2 is a promising research direction in resource utilization and sustainable energy development. However, there is still a...     

Invariant object recognition based on combination of sparse DBN and SOM with temporal trace rule

Multimedia Tools and Applications - This paper proposes a trace rule based self-organized map (SOM) model built upon a sparse 2-stage deep belief network (DBN). The combination of SOM and sparse...     

Evaluation of Localization Attacks on Power-Modulated Challenge–Response Systems

Location information should be verifiable in order to support new computing and information services. In this paper, we adapt the classical challenge-response method for authentication to the task of verifying an entity's location. Our scheme utilizes a collection of transmitters, and adapts the power allocations across these transmitters to verify a user's claimed location. This strategy, which we call a power-modulated challenge response, is able to be used with existing. wireless sensor networks. First, we propose a direct method, where some transmitters are selected to send ldquochallengesrdquo that the claimant node should be able to witness based on its claimed location, and for which the claimant node must correctly respond to in order to prove its location. Second, we reverse the strategy by presenting an indirect method, where some transmitters send challenges that the claimant node should not be able to witness. Then, we present a signal-strength-based method, where the node responds with its received signal strength and thereby provides improved location verification. To evaluate our schemes, we examine different adversarial models for the claimant, and characterize the performance of our power-modulated challenge response schemes under these adversarial models. Further, we propose a new localization attack, where a set of nodes collaborates to pretend that there is a node at the claimed location. This collusion attack can do tremendous harm to localization and the performance of the aforementined methods under collusion attack are explained. Finally, we propose the use of a rotational directional power-modulated challenge response, where directional antennas are used to defend against collusion attacks.     

Pseudoelastic behavior in Y1−xPrxBa2Cu3Oy compounds

Tensile tests show that ferroelastic loops always occur at 100–150 K, 200–250 K and room temperature in the Y_1–xPr_xBa₂Cu₃O_y samples withx=0 and 0.1 for whichT _c is 92 K and 82.5 K respectively, and the shape memory effect is always observed in the compact sample near 130 K, just similar to that of thermal elastic martensitic alloys. The loss fraction (W/W) which is proportional to the area of ferroelastic loop as a function of temperature shows that there always exist static hysteresis (W/W) peaks at 130 K and 110 K which are attributed to the phaselike transition (PLT) characterized by the jump of lattice parameters. No ferroelastic loops and shape memory effect are observed in the range of 100 K to 150 K for the lowerT _c samples withx=0.3, 0.4 and 0.6.