共查询到19条相似文献,搜索用时 171 毫秒
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报导了染料激光碎石技术的新进展,论述了激光碎石的诸多优越性以及选择灯泵染料激光器的原因及研究近况。 相似文献
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目的:比较U-100双频激光碎石术与气压弹道碎石术治疗输尿管结石的疗效和实用性.方法:采用U-100双频激光碎石术治疗输尿管结石498例,气压弹道碎石术342例.比较两组手术时间、单次手术碎石率、结石排净时间、手术并发症的差异.结果:U-100双频激光碎石术手术时间为29.8±5.4 min,少于气压弹道碎石术44.3±9.5min,P<0.05;U-100双频激光碎石术(U-100组)单次手术输尿管结石碎石率为93.2%(464/498),高于气压弹道碎石术(PL组)的79.8%(273/342),P<0.05;U-100组的结石排净时间为18.5±4.4d,短于PL组的31.2±5.8d,P<0.05;U-100组并发症相对较少,无一例发生输尿管穿孔;而PL组9例发生输尿管穿孔.结论:U-100双频激光碎石术的疗效和实用性明显优于气压弹道碎石术. 相似文献
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激光自诞生以来就在众多领域中有着广泛应用,激光碎石技术就是其中之一。相比目前激光碎石技术的“金标准”钬激光器,掺铥碎石光纤激光器在近些年不断发展,而且逐步被证明可实现更快的碎石速率与粉末化碎石、产生较小的碎石反推力、允许更高的液体灌溉速率等手术优点,同时整机系统支持免水冷工作、高电光效率运转、全光纤高效耦合以及大幅度体积缩减,因此受到了越来越多的关注。本文从连续性、准连续型和纳秒短脉冲型掺铥光纤激光器三个角度出发,详细总结了掺铥光纤激光器的部分重要研究进展及其在碎石领域的研究,介绍了掺铥光纤激光器用于碎石的优势与原理,并展望了未来研究的方向和挑战。 相似文献
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目的:评估双频双脉冲激光联合钬激光碎石术治疗复杂性输尿管结石的疗效。方法:采用输尿管镜双频双脉冲激光联合钬激光治疗复杂性输尿管结石39例,其中输尿管结石合并息肉30例,输尿管结石合并输尿管狭窄9例。先应用钬激光切除输尿管结石下方的息肉或切开结石下方的狭窄处,再应用双频双脉冲激光进行碎石。结果:一次手术碎石成功率为92.3%,2例发生结石上漂,1例输尿管穿孔转开放手术。平均手术时间39m in,平均激光工作时间25m in,术后平均住院3.2天。结论:应用双频双脉冲激光联合钬激光碎石术治疗伴有息肉或狭窄的复杂性输尿管结石是安全、有效的。 相似文献
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结石表面光吸收系数的非破坏性测量1前言激光碎石术在治疗人体肾结石、原结石、胆结石和涎晚结石等方面已经取得成功。现在有一种论点指出:激光碎石的机理是通过等离子体的形成与膨胀,传导到组织的激光光能量被转换成破坏性的冲击波能量,从而导致激光碎石。等离子体形... 相似文献
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运用等效线路图法研究了3种典型的声学结构对手机扬声器的频响特性的影响,并加以实验验证。通过与相同容积的简单结构的频响特性比较,分析了这三种结构各自的优缺点,并提出了设计建议。 相似文献
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当电动机容量较大时,大功率变频器的输入谐波对电网的影响以及输出谐波对电动机的影响成为了交流变频系统中突出的问题。为了减小大功率变频器的谐波,普遍采用多脉动整流、变压器耦合输出、多电平和单元级联技术,形成了以多脉动整流拓扑或多电平拓扑为输入级、以变压器耦合输出或多电平输出拓扑为输出级的大功率变频器主电路,以及多重化结构的大功率变频器主电路。本文对目前几种有代表性的高压变频器主电路拓扑及输入输出谐波进行了分析,并与IEEE-519标准进行比较,研究了变频器的谐波特性。 相似文献
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Kelley C.A. Sridhara D. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(11):4013-4038
This paper presents a detailed analysis of pseudocodewords of Tanner graphs. Pseudocodewords arising on the iterative decoder's computation tree are distinguished from pseudocodewords arising on finite degree lifts. Lower bounds on the minimum pseudocodeword weight are presented for the BEC, BSC, and AWGN channel. Some structural properties of pseudocodewords are examined, and pseudocodewords and graph properties that are potentially problematic with min-sum iterative decoding are identified. An upper bound on the minimum degree lift needed to realize a particular irreducible lift-realizable pseudocodeword is given in terms of its maximal component, and it is shown that all irreducible lift-realizable pseudocodewords have components upper bounded by a finite value t that is dependent on the graph structure. Examples and different Tanner graph representations of individual codes are examined and the resulting pseudocodeword distributions and iterative decoding performances are analyzed. The results obtained provide some insights in relating the structure of the Tanner graph to the pseudocodeword distribution and suggest ways of designing Tanner graphs with good minimum pseudocodeword weight. 相似文献
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Several major deconvolution techniques commonly used for seismic applications are studied and adapted for ultrasonic NDE (nondestructive evaluation) applications. Comparisons of the relative merits of these techniques are presented based on a complete set of simulations on some real ultrasonic pulse echoes. Methods that rely largely on a reflection seismic model, such as one-at-a-time L(1) spike extraction and MVD (minimum variance deconvolution), are not suitable for the NDE applications discussed here because they are limited by their underlying model. L(2) and Wiener filtering, on the other hand, do not assume such a model and are, therefore, more flexible and suitable for these applications. The L(2) solutions, however, are often noisy due to numerical ill conditions. This problem is partially solved in Wiener filtering, simply by adding a constant desensitizing factor q. The computational complexities of these Wiener filtering-based techniques are relatively moderate and are, therefore, more suitable for potential real-time implementations. 相似文献
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V. V. Zenin A. A. Stoyanov S. V. Petrov B. A. Spiridonov 《Russian Microelectronics》2013,42(5):288-300
The design-and-manufacturing features of the development of discrete semiconductor devices and 3D wares are considered. Coatings of contact areas of crystals and package traverses for the formation of internal connections in 3D wares are analyzed. It is established that the following coatings should be primarily considered in assembling 3D wares: aluminum and copper metallization on crystals; and gold, silver, nickel, its alloys, and galvanic aluminizing on the package traverses. The data on the deposition technology of these coatings are presented. 相似文献