关于深孔加工工艺的探讨

深孔加工一直是孔加工中的难点,由于深孔是半封闭式切削加工,不能直接观察成孔的过程和内部状况,所以必须对其工艺进行合理选择与设计。随着机械行业的高速发展,需要深孔加工的产品数量越来越多,如何保证深孔加工的质量已成为当前迫在眉睫的课题。     

超薄印制电路板金属化半孔成型加工研究

金属化半孔不仅能实现导通功能,而且能满足孔壁的焊接功能,实现边缘连接器、指示器等元器件的安装。文章提出一种金属化半孔成型加工工艺,解决超薄印制电路板金属化半孔成型加工孔壁铜皮翘起、毛刺残留难题,提升产品品质,提高生产效率。     

HDI板埋孔填胶工艺研究

HDI板在生产过程中用LD半固化片填胶的加工工艺。分别通过理论计算分析了LD半固化片(1037)理论含胶量及实际所需胶量的一种量化关系,并以田口-DOE实验法探讨了LD半固化片填胶过程中表面凹陷产生的主要原因,对制作HDI使用半固化片直接填孔选材与工艺有重要的参考意义。     

半固化片填孔性能方法的研究与探讨

文章通过试验研究不同类型半固化片的填孔规律,总结出评判半固化片的填孔性能的方法,对制作HDI使用半固化片直接填孔选材与工艺有重要的参考意义。     

超快激光微孔加工工艺研究进展

硬脆和复杂结构材料上的微孔加工是超快激光的主要应用之一。超快激光微孔加工的质量和加工效率受单脉冲能量、频率、脉宽、偏振等光束特性以及加工方式、被加工材料、辅助方式等多个因素的综合影响。不同的工艺参数组合将导致不同的孔圆度、孔锥度、加工缺陷以及侧壁和孔边缘的表面质量,对工艺参数进行研究是超快激光微孔加工的核心问题之一。本文从光束特性、加工及辅助方式、材料特性等方面综述了目前超快激光微孔加工工艺的研究进展,总结并对比了不同研究中对同一工艺参数的研究结果。最后,提出了目前研究存在的不足并展望了今后提升效率和加工质量的方向。     

3μm铜箔CO2激光直接烧靶工艺研究

为满足印制电路板(PCB)线路等级需求,需要采用改进型半加成工艺(mSAP)并使用3μm及以下的附载体极薄铜箔。采用3μm mSAP工艺时,激光钻孔加工使用开窗流程。为保证对位精度,高精度曝光时抓取内层靶标来对位。利用CO₂激光加工的积热效应,验证了3μm铜箔CO₂激光直接烧靶的可行性,其中烧蚀靶标的激光叠孔设计和激光加工参数是影响烧靶效果的关键因子。通过研究输出了最优的叠孔设计方案和最适合的激光加工参数。结果表明,采用CO₂激光直接烧靶加工,凹点靶标和凸点靶标都可以100%满足高精度曝光抓取靶标的需求。     

直接使用半固化片填机械盲孔的研究

机械盲孔是指采用机械钻孔方式形成的盲孔,机械盲孔均需要做填孔处理,并必须保证盲孔被填满,否则,填不满盲孔在后续制程中藏药水,造成盲孔孔铜腐蚀,影响可靠性。业界主要采用两种方式来填机械盲孔:一种是盲孔层采用树脂填孔工艺,另一种是压合时直接利用半固化片熔融的树脂填孔。采用半固化片直接填机械盲孔具有流程短、成本低的特点,是一种优异的加工技术流程。本文对直接使用半固化片填机械盲孔进行了系统的研究,总结出半固化片的树脂种类、Filler含量、树脂含量、生产厂家以及压合程序设计对半固化片填盲孔能力的影响,并分析这些因素影响半固化片填盲孔能力的机理。     

飞秒激光加工气膜孔的热障涂层表面残余应力研究

针对飞秒激光打孔后孔周热障涂层残余应力演化问题，采用cosα法对不同飞秒激光工艺制备的气膜冷却孔周围残余应力进行步进式逐点测量，结果表明，喷涂态热障涂层和激光打孔后气膜孔周围的涂层表面应力皆是以淬火应力主导的残余拉应力；不同飞秒激光加工工艺、不同的孔尺寸下，气膜孔周围都存在一个明显的径向残余应力影响区，且在该影响区内残余应力呈线性递减；由于飞秒激光热效应形成的飞溅物的影响，不同工艺制备的气膜孔周围径向残余应力场无明显差别，改变气膜孔直径无法改善这种热效应。     

印制板金属化孔工艺研究

本文总结了当前最流行的孔金属化新工艺做了比较深入地分析，并对金属化孔的技术要求，金属化孔的工艺过程、金属化孔的质量检查、金属化孔的发展动向和印制板加工的质量控制等五个部分来进行具体的叙述。     

LTCC半切割基板制作技术研究

LTCC应用中，有些用户要求提供不切透的大尺寸联片LTCC基板，以方便后步自动贴装、自动粘片加工。本文选取为某用户加工的蓝牙基板为例，介绍了LTCC半切割基板制作技术，并从LTCC半切和激光半切的角度阐述了两种半切加工方法和工艺优化过程，对两种工艺试验结果进行了分析比较。     

Cross-Layer Collaborative In-Network Processing in Multihop Wireless Sensor Networks

Emerging wireless sensor network (WSN) applications demand considerable computation capacity for in-network processing. To achieve the required processing capacity, cross-layer collaborative in-network processing among sensors emerges as a promising solution: sensors do not only process information at the application layer, but also synchronize their communication activities to exchange partially processed data for parallel processing. However, scheduling computation and communication events is a challenging problem in WSNs due to limited resource availability and shared communication medium. In this work, an application-independent task mapping and scheduling solution in multihop homogeneous WSNs, multihop task mapping and scheduling (MTMS), is presented that provides real-time guarantees. Using our proposed application model, the multihop channel model, and the communication scheduling algorithm, computation tasks and associated communication events are scheduled simultaneously. The dynamic voltage scaling (DVS) algorithm is presented to further optimize energy consumption. Simulation results show significant performance improvements compared with existing mechanisms in terms of minimizing energy consumption subject to delay constraints     

An efficient online‐battery aware geographic routing algorithm for wireless sensor networks

Wireless sensor networks (WSNs) are being used in a wide variety of critical applications such as military and health‐care applications. Such networks, which are composed of sensor nodes with limited memory capacity, limited processing capabilities, and most importantly limited energy supply, require routing protocols that take into consideration these constraints. The aim of this paper is to provide an efficient power aware routing algorithm for WSNs that guarantees QOS and at the same time minimizes energy consumption by calculating the remaining battery capacity of nodes and taking advantage of the battery recovery process. We present an online‐battery aware geographic routing algorithm. To show the effectiveness of our approach, we simulated our algorithm in ns2 and compared it with greedy perimeter stateless routing for wireless networks and battery‐aware routing for streaming data transmissions in WSNs. Copyright © 2009 John Wiley & Sons, Ltd.     

On-call processing delay in high speed networks

In future BISDN networks, significant burdens will be placed on the processing elements in the network since call routing and admission policies will be more computationally intensive than those in present day networks. Thus, the bottleneck in future networks is likely to shift from the communication links to the processing elements. The delays at these elements are influenced by their processing capacity and factors such as; routing algorithms, propagation delays, admission control functions, and network topology. The goal of this paper is to characterize the behavior of these factors on the call setup time and accepted call throughput. This behavior is examined for three sequential routing schemes and two flooding routing schemes under various network parameters and different forms of admission control. The results of our study indicate that processing capacity and the admission control function can affect the call setup time and accepted call throughput significantly while propagation delay does not affect these performance measures significantly     

DSP芯片在实时图像处理系统中的应用

在通用计算机上用软件实现图像处理，要占用CPU几乎全部的处理能力，且速度相对较慢。数字信号处理器(DSP)的可编程性和强大的处理能力使其可用于快速实现各种数字信号处理算法，在图像处理领域，尤其在实时图像处理系统中得到了广泛应用和发展。本文介绍了DSP芯片及其在实时图像处理系统中的开发、应用及发展方向。     

Minimizing call setup delay in ATM networks via optimal processingcapacity allocation

This paper considers the problem of process allocation in designing real-time call setup for asynchronous transfer mode (ATM) networks. With the constraint of finite processing capacity in a realistic ATM switching system, we aim to minimize the call setup delay by avoiding the potential bottleneck process. Our approach is to distribute and balance the processing loads among call control processes via optimal capacity allocation. The derived results can provide important and useful guidelines in system design and performance evaluation     

Mapping density to bandwidth in tree-based wireless sensor networks

Sensors in a wireless sensor network (WSN) are often resource constrained: they are limited in processing speed, storage capacity and energy. Therefore, most of the research projects in WSN domain are aiming at the energy issue, while leaving some equally crucial issues unexplored, like the QoS support. In this paper, we present QoS support in WSN while highlighting the QoS mapping issue, a complex process in which QoS parameters are translated from level to level and we present a case study of a TDMA tree-based clustered WSN, where network density at the user level is mapped to bandwidth at the network level. We end our paper with simulations that prove our formulas and highlight the relationships between QoS parameters.     

System capacity of F-TDMA cellular systems

We study the system capacity of cellular systems with time-division multiple access, slow time-frequency hopping (F-TDMA), and conventional single-user processing at the receivers. System capacity is formally defined as the maximum of the product of the number of users per cell times the user spectral efficiency for a given maximum outage probability. We adopt an information-theoretic definition of outage as the event that the mutual information of the block-interference channel resulting from a finite number of signal bursts spanned by the transmission of a user code word falls below the actual code rate, because of fading, shadowing, and interference. Starting from this definition, we develop a general framework which naturally takes into account many different aspects of F-TDMA cellular systems like channel reuse, channel utilization, waveform design, time-frequency hopping, voice activity exploitation, handoff, and power control strategies. Most importantly, our analysis does not rely on the choice of a particular coding scheme and can be applied to a very large class of systems in order to find guidelines for capacity-maximizing system design. A numerical example based on a typical urban mobile environment shows that there is a considerable capacity gap between actual F-TDMA systems and the limits predicted by our analysis. However, this gap can be filled by carefully designed (practical) systems, which make use of conventional single-user processing and simple coded modulation schemes     

高能激光单晶硅反射镜纳米精度控形控性制造技术

单晶硅反射镜是高能激光系统中的重要元件,其加工质量直接影响着高能激光系统的整体性能指标。针对单晶硅反射镜加工过程中产生的各类缺陷问题,本研究团队提出了采用超精密切削、浸没式抛光、磁流变抛光、离子束抛光等超精密加工方法来提升单晶硅元件的加工质量,并开展了相关研究。本文主要综述了本团队近几年在单晶硅制造技术领域取得的研究进展,包括单晶硅纳米精度表面控形制造技术、单晶硅纳米精度本征表面控性生成方法、纳米精度控形控性组合工艺等一系列关键技术。通过探讨高能激光单晶硅元件制造的现状与关键技术,为实现单晶硅元件纳米精度控形控性制造提供技术支撑。     

An Architecture of Scalable ATM Switching System and Its Call Processing Capacity Estimation

In this paper, we define the general requirements of ATM switching systems such as scalability, distributed fashion, and modularity. Also we propose a practical implementation of a scalable ATM switching system whose capacity can be easily expanded. Firstly, the architecture of the system is discussed with an emphasis on system scalability, modularity of subsystems and the simple control network of the design requirements. Secondly, we suggest the three types of distributed call/connection control schemes that are suitable for our switching system. We also estimate their call processing capacity on the average and make a comparison of them under the various system architectures. Since our scalable switching system can be constructed to perform the call processing functions on the various levels of the system capacity, it has much adaptability at the various evolution phases or regions of the network environment.