直接蒸发冷却填料的形式和选择应用

主要介绍了蒸发冷却空调技术的发展及其技术,概述了直接蒸发冷却填料的几种形式,分析了几种常用填料的性能优缺点及其选择使用。     

有机填料直接蒸发冷却试验研究

对celdek有机填料的直接蒸发冷却进行试验研究,分析了冷却效率、填料阻力和体积换热系数的影响因素,并进行经验公式拟合,可以为celdek有机填料直接蒸发冷却机组的设计使用提供参考。     

填料—高压微雾复合式直接蒸发冷却空调机组的设计

以一台55000m3/h风量的填料―高压微雾复合式直接蒸发冷却空调机组为例,根据组合式空调机组的设计要求,提出填料―高压微雾复合式直接蒸发冷却空调机组的设计步骤及选型方案,以便更多的工程人员了解该组合式空调机组的特点及计算方法,为工程设计人员提供参考依据。     

高湿度地区直接蒸发冷却空调机组的性能评价

随着蒸发冷却技术的发展,该技术被应用于不同气候、不同功能的建筑物。通过在高湿度地区的南通,模拟海南某核电站的室外气象参数测试直接蒸发冷却空调的风量、温降和冷却效率。测试结果表明,在南通模拟的室外气象参数下,即使是室外相对湿度达到74.9%的情况下,直接蒸发冷却空调的温降仍可以达到3.8℃,冷却效率可以达到71.4%。可以推断蒸发冷却空调在高湿度地区核电站同样能发挥其作用。     

滴水式填料与高压微雾直接蒸发冷却换热及影响因素分析

针对目前不断完善的直接蒸发冷却技术,通过对直接蒸发冷却与水接触方式的基本原理及热、质交换,分析空气与水的接触面积、空气与水接触时间、空气的质量流量、空气的均匀度、空气的水气比、阻力等因素对直接蒸发冷却效率的影响。     

浅谈直接蒸发冷却通风降温术语及其应用

通过诠释直接蒸发冷却通风降温术语,进而对两种系统形式术语的正确表达及其定义进行了探讨,并简单阐述了直接蒸发冷却通风降温的重要性以及单元式直接蒸发冷却设备相关标准,认为在以显热散热量为主的大空间工业厂房、高温车间等产生工艺余热的场所采用蒸发冷却技术是非常经济合理的。     

对现有几种蒸发冷却空调适应性区域划分方法的分析

介绍了目前国内现有的蒸发冷却空调适应性的几种分区方法,分析了它们各自的特点以及适用场合,以期使蒸发冷却空调技术的推广应用更为广泛和合理。     

转轮式热回收型间接-直接蒸发冷却空调机组的性能测试与分析

以一台转轮式热回收型间接一直接蒸发冷却空调机组为测试对象,该转轮式热回收型间接．直接蒸发冷却空调机组设有金属网孔粗效过滤器、转轮式热回收器、亲水性高分子纤维填料、送风机、排风机。本次测试主要对其样机的转轮式热回收段的冬季运行进行测试,得到其送风量、排风量、风速、热回收效率、温度、相对湿度、阻力等性能参数。通过计算分析得到：排风与新风此从0．7增加到1．2,转轮式热回收器的热回收效率从62％增加到82％,同时在本次测试范围内,转轮式热回收器的热回收效率随着排风入口干球温度的增加,效率呈现下降趋势。     

不同形式的蒸发冷却空调设计方案的对比分析

主要对吐鲁番地区进行了3种空调方案的设计,并将其处理过程在温湿图上表示出来。通过对3种不同的处理方案的结果的分析以及对3种方案能效比的计算,最后对蒸发冷却空调系统设计提出建议。     

蒸发冷却空调系统的能耗模拟分析及应用

对目前蒸发冷却空调系统的主要存在形式直接蒸发冷却系统、间接.直接蒸发冷却复合系统、蒸发冷却-机械制冷联合系统以及系统数学模型进行介绍,并通过西安工程大学蒸发冷却研究团队对各系统的能耗分析以及实际使用效果,说明蒸发冷却空调系统的节能性。     

改善洁净系统空调机组性能的几点认识

根据多年的实践经验，对质量有差异的空调机组性能进行对比，找出关键点，旨在倡导全面改善洁净空气系统空调机组的性能，以实现洁净空气系统的经济、稳定运行。同时也促进空调行业的长足发展。     

Evaluating secrecy performance of cooperative NOMA networks under existence of relay link and direct link

The secrecy performance of a nonorthogonal multiple access (NOMA) system is examined in this study by employment of a dual‐hop decode‐and‐forward (DF) relay under existence of eavesdropper. Due to the fact that the relay is trusted or untrusted device and thus eavesdropper may wiretap information from the base station or the relay. In this regard, three scenarios related to trusted and untrusted relays are proposed, with different assumptions on the information overhearing ability of the eavesdropper; ie, the first scenario is that an eavesdropper overhears signal from the relay while the BS is overheard by eavesdropper in the second scenarios. More specifically, we derive closed‐form expressions for the secure probability metrics when the direct and relay links experience independent Rayleigh fading. There metrics include strictly positive secrecy capacity (SPSC) and the secure outage probability (SOP). Furthermore, secure performance of traditional orthogonal multiple access (OMA) is also provided as further comparison with NOMA counterpart. We analyze the influence of main coefficients such as the target rates and the transmit SNR factors on the secrecy performance. Our results specify that for reasonable selection of such parameters, secrecy performance can be enhanced remarkably. Numerical results are delivered to corroborate the derived results.     

Evaluating the performance of software-reliability models

A method of quantifying the performance of software reliability models that was proposed by B. Littlewood (1980) is investigated. The method is essentially a Kolmogorov-Smirnov goodness-of-fit test. It is demonstrated that although the Littlewood method is rather unconventional, the standard Kolmogrov-Smirnov tables (for the simple hypothesis) can be directly applied. On this basis, the kind of performance that can be anticipated from an ideal software reliability model is shown. A performance which overcomes a weakness in the Littlewood method is presented     

浅析燃气直接加热空调机组

本文借助于汽车行业涂装喷漆生产线的新风补风系统及组装线的混风系统在冬季空调供热的使用工况下,介绍了两种应用于组合式空调机组中的新型空气加热方式-直接燃烧式燃气加热空调机组和间接燃烧式燃气加热空调机组,这两种系统均具有升温快、输出热量大、效率高、调节灵敏、安全卫生、经济、节能等显著特点,将会越来越广泛地应用于各行各业。     

Evaluating performance of high-speed multiaccess networks

An overview of high-speed multiaccess networks is presented, and their potential roles are discussed. It is shown that network response time sufficiently characterizes network performance under a number of scenarios and that more invaluable performance information, like end-to-end throughput, can be derived from these results. Examples based on the operating fundamentals of token-passing (e.g. FDDI), slotted (e.g. DQDB), and other approaches to high-speed networking are given. These approaches are compared for scenarios that require different measures of performance, and it is shown that their performance matches the needs of the environment from which they come     

空调机组盘管防冻技术措施

空调机组盘管(加热器、表冷器)防冻是北方区域的难题,通过分析静止状态、流动状态两种情况下水结冰的原理,总结空调机组加热器、表冷器防冻措施,提出设计、安装的关键控制要点。     

Evaluating the communication performance of an ad hoc wirelessnetwork

Adaptive and self-organizing wireless networks are gaining in popularity. Several media access and routing protocols were proposed for such networks and the performance of such protocols were evaluated based on simulations. In this paper, we evaluate the practicality of realizing an ad hoc wireless network and investigate on performance issues. Several mobile computers were enhanced with ad hoc routing capability and were deployed in an outdoor environment and communication performance associated with ad hoc communications were evaluated. These computers periodically send beacons to their neighbors to declare their presence. We examined the impact of varying packet size, beaconing interval, and route hop count on route discovery time, communication throughput, end-to-end delay, and packet loss. We had also performed mobility experiments and evaluated the route reconstruction time incurred. File transfer times associated with sending information reliably (via TCP) over multihop wireless links are also presented. The experimental results obtained revealed that it is feasible to augment existing wireless computers with ad hoc networking capability. End-to-end performance in ad hoc routes are less affected by beaconing intervals than packet size or route length. Similarly, communication throughput is more dependent on packet size and route length with the exception at very high beaconing frequencies. Packet loss, on the other hand, is not significantly affected by packet size, route length or beaconing frequency. Finally, route discovery time in ad hoc wireless networks are more dependent on channel conditions and route length than variations in beaconing intervals     

Evaluating the performance of convolutional codes over block fadingchannels

This correspondence considers union upper bound techniques for error control codes with limited interleaving over block fading Rician channels. A modified bounding technique is presented that relies on limiting the conditional union bound before averaging over the fading process. This technique, although analytically not very attractive, provides tight and hence useful numerical results     

软打样显示器的显色性能研究

显示器的显色性能会随着使用时间以及环境条件的改变而变化。本文以显示器显色性能为研究对象,设计一套系统的显示器性能测试实验,采用正交试验分析色温、亮度和Gamma值对EIZO CG247和Dell P2714H显示器显色能力的影响,为显示器确定合适的校准条件。此外,还对显示器的空间均匀性和时间稳定性进行了对比测试,以更好地将显示器应用于软打样。实验结果表明:对于两台显示器,在三个校准参数中,都表现为色温对显示器呈色的影响最大,Gamma值次之,亮度最小;两显示器的最佳显色参数都为色温6 500 K,亮度120cd/m~2,Gamma值2.2,但是Dell P2714H的平均色差1.06大于EIZO CG247显示器的0.64;并且两显示器在空间均匀性和时间稳定性方面表现相接近。     

Evaluating the performance of turbo codes and turbo-codedmodulation in a DS-CDMA environment

Turbo codes have received great attention due to their outstanding performance. Unfortunately, a high performance is associated with large transmission delays, prohibiting an application for speech transmission. Hence, the aim of this paper is the comparison of turbo codes employing short interleavers with convolutional codes in terms of bit error rate performance and computational effort. Additionally, a pragmatic approach of bandwidth-efficient turbo-coded modulation is considered. Analyzing the structure of the transmitter and receiver, interesting results are presented concerning the design of the mapper. Furthermore, a new very simple soft-output demodulation algorithm is derived. In order to compare turbo codes with convolutional codes under realistic conditions, both are embedded in a direct sequence (DS) code division multiple access system. Besides this comparison, a compromise between a high coding gain (low code rate) and high direct-sequence spreading is worked out, including the consideration of the turbo-coded modulation scheme. Simulation results indicate that turbo codes with small block interleavers do not outperform conventional convolutional codes. Furthermore, it is shown that for coherent demodulation, low code rates and low DS spreading is superior to high code rates and high DS spreading