用Nd：YAG激光加工玻璃内部结构

用Ｎｄ：ＹＡＧ激光加工玻璃内部结构１．引言用ＣＯｚ激光加工玻璃，如切割、打孔、标记在实践中已为众所周知’‘，””“。这是由于玻璃能吸收ＣＯ。激光器８０～９５％（视玻璃种类不同）的红外光。图１示出各种玻璃的透过率与波长的关系。由于波长入一１卜ｍ时吸收可...     

激光增强切割工场的竞争力

美国伊利诺斯州Erie工业产品公司自1946年以来一直是一家服务于公司的金属加工工场。1982年他们购买了一台CO2激光切割机，从而成为全美最先进的加工工场之一。“我们是芝加哥地区第一批购买激光器的公司之一。的确收到了效果。”公司总经理P.Selleck说。之后，公司又购买了三台激光器。作为加工零部件批量在1到1000之间的小工场，以前最昂贵的机械就是硬质工具。“现在，有了激光器，我们能够避开加工每种零件的工具成本问题。结果是，我们能够更快地转换工件。’剧总经理F.Baker说，“收外，我们还能加工这样的部件，其形状是用硬质冲…     

高功率CO2激光加工设备的泵浦电源及研究状况

就高功率气体激光加工设备在广泛应用中，对泵浦电源性能和特点提出越来越高的要求，阐述了高功率激光电源的研究状况，论述了开关电源应用于激光设备的技术优势，提出了激光泵浦电源的发展方向。     

激光加工技术发展现状及展望

本文论述了用于激光加工的各类激光器、光学系统、工件系统以及激光加工应用开发的发展现状与水平;并根据近期激光加工市场动态,预测了“八五”期间激光加工技术的发展趋势,提出了我国激光加工技术近期的研究方向。     

激光切割系统功率实时控制研究

激光功率对切割质量具有重要的影响,功率过大容易产生过烧现象。为了保证切割质量,研究了激光功率与切割速度的关系,基于可编程多轴运动控制器提出了激光功率实时控制的方法,使用开放性编写应用程序进行串口通信调整功率的方式实现激光功率的实时控制。采用这种方法进行激光切割试验,当激光功率能够随切割速度实时变化时,可以避免烧角现象。结果表明,此方法可以有效地提高切割质量,并且保证了激光切割的效率。     

激光切割系统功率实时控制研究

激光功率对切割质量具有重要的影响,功率过大容易产生过烧现象.为了保证切割质量,研究了激光功率与切割速度的关系,基于可编程多轴运动控制器提出了激光功率实时控制的方法,使用开放性编写应用程序进行串口通信调整功率的方式实现激光功率的实时控制.采用这种方法进行激光切割试验,当激光功率能够随切割速度实时变化时,可以避免烧角现象.结果表明,此方法可以有效地提高切割质量,并且保证了激光切割的效率.     

中低功率双CO_2激光切割机的开发与应用

研究了大功率单CO2激光切割机和小功率双CO2激光切割机的切割原理,分析了在用这两种形式的激光切割机切割非金属材料木质模切板时,激光功率、切割速度与切割深度、切割的缝形缝宽之间的关系。试验结果表明,用中小功率双CO2激光切割机切割非金属木质板材,无论是设备的制造成本、运行成本,还是切割的精度和缝形缝宽,同用大功率单CO2激光头切割机相比有很多优势。     

武汉团结激光研制的全国功率最大的激光器

武汉团结激光公司成功研制出4000W激光器．这是迄今为止全国功率最大的激光器。该激光器仅需5min即可切割10m长、20mm厚的高强桥梁钢，打破了国产激光器不能切割桥梁钢的历史。     

激光材料加工技术的发展方向

激光在制造业中的应用特色是产品的高质量 ,加工的高效率 ,人工和用材的经济以及生态环境清洁。激光技术的发展有其社会效益 :为有能力的职工创造工作场所 ,这将促进教育和文化水平的提高。战略目的是保存和发展积累的技术和工业潜力 ,使其适应现代条件。激光加工多种多样 ,包括电子元件的精密微焊接、汽车和船舶制造中的焊接以及坯料制造中的切割。有不同种类的表面处理 ,如热处理、表面修整、合金化、打标等等。在激光帮助下许多方面已获得用其他方法不能实现的技术和经济效益。有许多用普通焊接方法实现的技术加工 ,从质量和产量的观点看…     

New high power, high performance power converter systems

A new, high performance, low cost power converter system architecture is proposed. The system consists of a main converter and a multifunctional load conditioner. The main converter deals with most of the power flow running at a low switching frequency. The load conditioner is designed at a much lower power level running at a high-switching frequency. The load conditioner can (1) act like a current source and inject harmonic currents required by the load; (2) act like an active resistor to provide damping to the main converter; and (3) for three-phase inverters, decouple the coupling sources in the main inverter model in the rotating coordinates to make the control loop design for the main inverter much easier. The concept has been proved by simulation and experimental results on a 150 kW high performance three-phase utility power supply prototype. The proposed system configuration can be used in high power DC-DC converters, inverters, PFC and UPS applications     

Utility-based power control with QoS support

This paper addresses the issue of incorporating QoS requirements expressed in terms of some minimum SIR targets into the traditional utility-based power control problem. As suitable projection methods seem to be not amenable to distributed implementation, we first focus on a primal-dual algorithm to solve the utility-based power control problem subject to the SIR requirements. We prove a global convergence of the algorithm for a large class of utility functions and show that it can be implemented in a distributed wireless environment. However, the approach has an important drawback: An optimal solution may not exist as the SIR targets may be infeasible due to, for instance, channel effects. This motivates a reformulation of the problem so that an optimal solution always exists. We consider the possibility of using a barrier method to closely approach the desired SIRs of the users and combine this approach with the conventional utility-based power control problem to incorporate best effort users. We prove relevant properties of optimal solutions and propose a distributed recursive algorithm with global convergence. Finally, the performance of the proposed approaches is verified by simulations.     

毫米波生成系统中估算偏振模色散引起功率损耗的新方法(英文)

提出了一种在基于光外差法毫米波生成系统中估算由偏振膜色散(PMD)引起的功率损耗的新方法。不同于之前的方法,此方法将在光纤中传输的光载波视为一个随机过程,计算出了其自相关函数,并利用帕斯瓦尔定理估算功率损耗。利用此方法估算出在单模光纤(SMF)中由PMD引起的功率损耗,计算结果与之前方法得出的结果相似,证明了此方法的正确性。最后,直观地给出60 GHz信号在3个不同传输距离下由PMD引起的功率损耗。     

Sb-Se-based phase-change memory device with lower power and higher speed operations

A phase-change material of Sb/sub 65/Se/sub 35/ was newly proposed for the nonvolatile memory applications. The fabricated phase-change memory device using Sb/sub 65/Se/sub 35/ showed a good electrical threshold switching characteristic in the dc current-voltage (I-V) measurement. The programming time for set operation of the memory device decreased from 1 /spl mu/s to 250 ns when Sb/sub 65/Se/sub 35/ was introduced in place of the conventionally employed Ge/sub 2/Sb/sub 2/Te/sub 5/ (GST). The reset current of Sb/sub 65/Se/sub 35/ device also dramatically reduced from 15 mA to 1.6 mA, compared with that of GST device. These results are attributed to the low melting temperature and high crystallization speed of Sb/sub 65/Se/sub 35/ and will contribute to lower power and higher speed operations of a phase-change nonvolatile memory.     

Hybrid systems modeling for power systems

In this work a framework for modeling power systems using hybrid input/output automata (HIOA) is proposed. The system is assumed to consist of several distinct components. Some of them drive the continuous dynamics while others exhibit event-driven discrete dynamics. Such behavior is characterized by interactions between continuous dynamics and discrete events. Therefore the power systems are an important example of hybrid systems. This hybrid modeling process is applied to a simple power system.     

Outer loop power control in CDMA satellite systems with on-board power constraints

This paper aims at clarifying the role of the outer loop power control for CDMA satellite systems with on-board power constraints. If the inner loop of the power control is perfect, the channel turns into a AWGN channel and there is no need of the outer loop. In satellite CDMA systems, due to the longer propagation delay with respect to a terrestrial system, the inner loop of power control is only partly able to track power variations due to fast fading. Moreover, the Rice factor, which characterizes the channel statistics, can widely vary even if the user does not move but just because of the change of the elevation angle. Because of that, a wide range of target SNIR (and larger than in typical terrestrial systems) may be necessary to get the same BER performance. Therefore, the outer loop power control turns out to be essential to minimize the dynamic of the power link margins and avoid capacity degradations induced by the systematic use of static link margins. A semi-analytical model for the capacity evaluation has been developed, which is specifically intended for the power-limited satellite-to-mobile link with multi satellite reception. We found that the capacity gain with respect to a pure SNIR-based strategy (i.e., only inner loop) can reach the 40% of the total capacity in a single reception scheme. A smaller, but still noticeable capacity gain of the order of 20 - 30% is observed in presence of satellite diversity. Therefore, any dimensioning of CDMA satellite systems should not neglect this component of the power control.     

Adaptive power loading with BER-constraint for OFDM systems

for optimal BER and power distributions are derived in this article. Simulation results indicate the superiority of the proposed algorithm in terms of BER performance and algorithmic complexity.     

可时序控制的激光功率稳定系统

在锶原子光晶格钟实验中,为了应对多变的实验环境和复杂的实验需求,使得某些光路中的激光不仅能够保证功率稳定,还可以进行时序性调控,采用了声光调制的方法,基于声光晶体的衍射效率随加载于其上的射频功率变化而变化这一原理,建立了一套反馈控制系统,实现了激光功率的主动稳定以及功率设定值的时序性可控。结果表明,在该系统中激光会根据时序控制信号稳定地工作在控制范围内的任意功率强度上,与无功率稳定的状态相比,激光功率的稳定度从10-2量级提高到了10-4量级。该系统的特点在于能够对功率进行稳定的时序控制。     

Multiresolutional hierarchical decision support systems

Decision support systems gain better performance and higher accuracy by the virtue of building multiresolutional (multigranular, multiscale) representation, and employing multiscale behavior generation subsystem (planning and control). The latter are equipped by devices for unsupervised learning that adjust their functioning to the results of self-identification. We demonstrate that planning and learning are joint processes. The author's intention is to emphasize that the concepts of multiresolutional representation (MR) and multiresolutional decision support (MR-DSS) probably have in common a general significance that crosses the boundaries of particular domains of applications and disciplines. The paper explores this phenomenon. The ubiquity of a principle that somehow persistently delivers benefits to many areas of knowledge and technology seems to be more important than a habit to follow the pigeonhole principle of paper presentation.