大高宽比散热片制造方案

以大高宽比散热片的制造为对象,给出了大高宽比散热片翅片的几种加工方法,介绍了每一种制造方法的基本原理和优缺点,对散热片的加工制造具有一定的应用价值。     

Hydrothermal Synthesis of Oriented Anatase Films Consisting of Columnar Aggregates and Their Wetting Properties

We hydrothermally synthesized anatase films on Ti substrates from transparent aqueous solutions of layered titanate colloids. The morphology and wetting properties of the films were examined. The films consisted of columnar aggregates grown on the Ti substrates, which resulted in high orientation. Randomly oriented films were obtained when alumina was used as a substrate, whereas the sol–gel precoating of a titanium oxide (TiO₂) layer on alumina substrates resulted in similar orientation as that of the films on Ti substrates. Thus, the presence of TiO₂ on the substrate surface plays an important role in the orientation of columnar aggregates. The columnar aggregates were similar in microstructure to the arms of a type of six-pointed star-like anatase aggregate synthesized hydrothermally from the same reaction solutions. They were composed of twins of tapered anatase nanocrystals, which provided a rough film surface. The film surface was highly hydrophilic and oleophilic due to the nanoscale roughness even when the film was not irradiated with UV light.     

气体对电容式原油含水率测量的影响分析

电容式传感器用于是原油含水率测量是一种有效的方法.由于测量过程中存在气体成分与油水混合状态等影响因素,该方法一直未广泛应用.文章从气液混合状态、气体体积含量两方面对气体成分的影响进行定性与定量分析.定性分析表明气液混合状态对测量结果有很大影响,而实际测量中气液混合的具体状态难以确定,故利用电容传感器对原油含水率测量必须进行分离气体;定量分析表明原油含水率的测量精度要求达到1%时,气体体积含量需控制在1%以内.文章还提出一种气液分离器,能够满足原油含水率测量中气液分离的要求.     

BT模式下轨道交通工程临电报装实践

在分析北京市轨道交通亦庄线工程施工用电特点的基础上,进行了施工用电方案优化,以"节省"、"快速"为突破口,高效地实施了工程施工用电工程,为工程施工提供了基础性保障。     

潜水钻机成孔垂直度控制技术

潜水钻机成孔工艺广泛应用于沿海地区第四系覆盖层的钻孔灌注桩施工中。介绍了潜水钻机的工作机理。在工程实践中,通过对钻机设备结构改良,对钻机成孔工艺方法改进等措施,使潜水钻机成孔垂直度控制技术得到了提高,在一些较深基坑钻孔灌注桩工程中得到了成功应用。     

裂缝性气藏转换波3D3C地震采集观测系统优选

川西坳陷深层须家河组气藏具有埋藏深、岩性致密、非均质性强、储层类型多样、气水关系复杂等特点，采用常规油气藏地震勘探技术难以取得很好的效果。转换波三维三分量（3D3C）勘探综合了纵波勘探和转换波勘探的优势，对于解决川西深层致密裂缝性储层的裂缝检测及含气性预测问题具有良好的应用前景。为此，针对深层气藏特点及裂缝检测的需要，对接收线距、束间滚动距、宽窄方位角、观测系统类型及覆盖次数等观测系统参数进行了分析论证，认为斜交方式、小接收线距、小滚动距、全方位、高覆盖次数等是决定采集数据随方位角和偏移距分布均匀的主要因素，可以更好地满足纵横波方位各向异性分析及横波分裂裂缝检测要求。设计了3个斜交砖墙式观测系统方案，并结合XC地区3D3C转换波勘探观测系统分析进行了优选。     

Capacity and Energy Efficiency of Multi-User Spectrum Sharing Systems with Opportunistic Scheduling

This paper investigates the capacity and energy efficiency of spectrum sharing systems with opportunistic user selection where a secondary network utilizes spectrum bands licensed to a primary network under interference regulation. In spectrum sharing systems, secondary users consume a fraction of their resources in sensing the channels to the primary users to comply with the interference constraints. Although more resources for sensing improve reliability and performance, the throughput loss due to time overhead and energy loss due to power overhead should be properly incorporated in performance evaluation. In this context, we define and derive a new metric ? average capacity normalized by the total energy consumption ? reflecting time and power overhead for spectrum sensing. Based on the developed framework, the optimal normalizedcapacity is investigated. We also propose a simple and practical suboptimal best-n scheme motivated by the infeasibility and high computational complexity of the optimal strategy, where n denotes the number of sensing secondary users. Our analytical and simulation results show that the proposed best-1 scheme is an energy-efficient technique with near optimality in terms of the capacity normalized by the energy consumption.     

Multi-user diversity in a spectrum sharing system

We investigate the effects of multi-user diversity in a spectrum sharing system where secondary users restrictively utilize a spectrum licensed to primary users only if interference perceived at primary users is regulated below a predetermined level. This interference regulation affects the characteristics of multiuser diversity gains previously known in non-spectrum sharing systems. Our numerical and analytical results show that the multiuser diversity gain in a spectrum sharing system increases differently according to conditions given by the transmit power of secondary users, P, and a predetermined interference temperature, Q - if P is sufficiently larger than Q, the multiuser diversity gain in terms of capacity scales like log2 (W (Ns)) similarly to a previously known scaling law in the non-spectrum sharing systems, where W(·) and Ns denote a Lambert W function and the number of secondary transmitters, respectively. However, the scaling law of multiuser diversity gain becomes log2(Ns) as P becomes sufficiently larger such that P ≫ QNs.     

Modeling of nonideal volume Bragg reflection gratings in photosensitive glass using a perturbed transmission matrix approach

Reflection spectra of volume Bragg gratings written in bulk photosensitive silicate glass for wavelength division multiplexing applications are modeled using a transmission matrix approach. This allows for the examination of the effects of spatial perturbations along the grating due to chirp, apodization, compositional inhomogeneities, and index contrast saturation leading to reflection spectra that are asymmetric about the Bragg peak. Effects of the nonlinear relationship between index contrast in the glass and exposure flux on the reflection spectrum is also studied. Volume Bragg gratings are fabricated in UV exposure-sensitive silicate glasses containing alkali-halide nano-crystalline domains, and their reflection spectra are compared with calculation. The magnitude and uniformity of the index changes observed in our glass gratings make them useful in a wide range of wavelength multiplexing applications.