钢质T形翅片管的池沸腾传热研究

<正>1 引言 随着对传热过程这一客观规律认识的深化以及加工制造技术的进步,人们已能研制开发出各式各样的强化换热元件,并在工程实践中取代传统的光滑管从而取得省材节能的双重效果。T.C.Canavos曾预言:到目前为止,强化换热元件的工作还仅仅是个开始,但是它的好处是那样地明显,以至于普通光滑管之被淘汰只不过是一个时间的问题了。多年来的实践证明这种预言是正确的,在强化换热元件中,强化液体泡核沸腾的元件的研究进展尤为突出,自60年代末期以后,先后有4种管型实现商品化,其中一种就是T形翅片管（Gewa-T）。T形翅片管自1978年问世于原联邦德国的Wieland Worke公司以后,国内外已有多项研     

Video key frame extraction by unsupervised clustering and feedback adjustment

In video information retrieval,key frame extraction has been recognized as one of the important research issues.Although much progress has been made,the existing approaches are either computationally expensive or ineffective in capturing salient visual content.In this paper,we first discuss the importance of key frame extraction and then briefly review and evaluate the existing approaches.To overcome the shortcominge of the existing approaches,we introduce a new algorithm for key frame extraction based on unsupervised clustring.Meanwhile,we provide a feedback chain to adjust the granularity of the extraction result.The proposed algorithm is both computationally simple and able to capture the visual content.The efficiency and effectiveness are validated by large amount of real-world videos.     

氢氧化镁——新型无机阻燃剂的开发与应用

本文综述了国内外氢氧化镁阻燃剂发展状况及在高聚物材料中的应用前景。     

二级可逆反应等温催化剂有效因子的简化计算

将等效温度法的应用拓宽至二级可逆反应,推导出球型等温催化剂有效因子的近似解析解,采用一氧化碳变换反应宏观动力学结果加以验证,证明该法简便可靠。     

基于柱坐标系的充型与凝固模拟系统的开发

针对铸造中大量遇到的回转类铸件,开发出基于柱坐标系的充型与凝固模拟软件系统。该系统有效地解决了基于直角坐标系的模拟软件在处理回转类铸件,尤其是薄壁铸件时遇到的网格剖分结果不对称,模拟结果局部失真等问题。初步的充型与凝固模拟结果表明,该系统的开发为解决回转类铸件,尤其是薄壁铸件时遇到的网格剖分结果不对称,模拟结果局部失真等问题提供了一种更加合适的方法。     

玉米淀粉胶的改进

介绍了一种制作玉米淀粉胶粘剂的改良方法,并从理论上论证了该法的可行性。从实践上证明了该法的优越性。     

Adaptive H∞ channel equalization for wirelesspersonal communications

In this paper, a new adaptive H_∞ filtering algorithm is developed to recursively update the tap-coefficient vector of a decision feedback equalizer (DFE) in order to adaptively equalize the time-variant dispersive fading channel of a high-rate indoor wireless personal communication system. Different from conventional L ₂ (such as the recursive least squares (RLS)) filtering algorithms which minimize the squared equalization error, the adaptive H _∞ filtering algorithm is a worst case optimization. It minimizes the effect of the worst disturbances (including input noise and modeling error) on the equalization error. Hence, the DFE with the adaptive H_∞ filtering algorithm is more robust to the disturbances than that with the RLS algorithm. Computer simulation demonstrates that better transmission performance can be achieved using the adaptive H_∞ algorithm when the received signal-to-noise ratio (SNR) is larger than 20 dB     

A Channel Sharing Scheme for Cellular Mobile Communications

This paper presents a channel sharing scheme, Neighbor Cell Channel Sharing (NCCS) , based on region partitioning of cell coverage for wireless cellular networks. Each cell is divided into an inner-cell region and an outer-cell region. Cochannel interference is suppressed by limiting the usage of sharing channels in the inner-cell region. The channel sharing scheme achieves a traffic-adaptive channel assignment and does not require any channel locking. Performance analysis shows that using the NCCS scheme leads to a lower call blocking probability and a better channel utilization as compared with other previously proposed channel assignment schemes.     

NaAlO2—CO2法制备拟薄水铝石规律的研究

研究ＮａＡｌＯ２－ＣＯ２法制备无三水氧化铝杂晶且Ｎａ＋含量较低的拟薄水铝石的规律。通过系统研究,解决了较高成胶温度下或较高ＮａＡｌＯ２溶液成胶浓度下生成三水氧化铝杂晶的问题;用ＮＨ４ＮＯ３或稀硝酸作洗涤介质,可有效地降低拟薄水铝石中Ｎａ＋含量;用循环洗涤方式降低洗涤介质用量;并探讨干燥温度影响拟薄水铝石胶溶性能的原因。     

加氢装置PV8505调压阀腐蚀调查

分析了PV8505调压阀产生严重冲刷腐蚀而失效的原因,并提出了相应的改造措施.