The covering radius of the (128,8) Reed-Muller code is 56 (Corresp.)

Letr_{i}be the covering radius of the(2^{i},i+ 1)Reed-Muller code. It is an open question whetherr_{2m+1}=2^{2_{m}}-2mholds for allm. It is known to be true form=0,1,2, and here it is shown to be also true form=3.     

如何提高移动通信高层室内覆盖的质量

随着3G丰富多彩的数据业务和多媒体业务的提升,用户对移动通话质量的要求越来越高,高层覆盖质量问题的投诉也越来越多。运营商必须尽快采取技术手段和网络优化解决高层室内覆盖的质量难题,以确保移动通信业务的不断发展。     

准视频点播技术在有线数字电视平台上的运用

分析了基于有线数字电视平台的准视频点播(NVOD)的系统构成;NVOD前端设备的功能及工作流程;NVOD系统在有线数字电视平台运用中的服务通道及带宽描述;数据网络上的视频广播与点播的实现方式.     

空心阴极限制性放电的氦-氖激光器

空心阴极放电是一种新的激励技术,用低电压就可放电,激活区为空心阴极中的阴极位降区与负辉区.由于这两个区域中存在高能电子,使氦原子激发产生足够多的亚稳态,故也可以获得氦-氖激光.本文报导了通过外部触发能实现低气压下的空心阴极放电,激光输出功率有几倍的增加.本文采用笛子形空心阴极,它是内径为4毫米、长度为55厘米的无氧铜管, 每隔5厘米开一个孔,对准孔的位置上面安装上阳极,共有十个阳极,如图1所示.     

The voice of the computer is heard in the land (and it listenstoo!) [speech recognition]

The authors describe how computers are now interacting with human beings through speech and accomplishing useful work. As such, the machines are doing what most two-year-olds can do: identify spoken words and answer back     

The construction of M-ary (d,∞) codes that achieve capacityand have the fewest number of encoder states

The existence of 100% efficient (i.e., capacity-achieving) fixed-rate codes for input-constrained, noiseless channels is guaranteed provided the channel has rational capacity. A class of M-ary runlength-limited (M,d,∞) constraints was shown in previous work to have rational capacity. In this correspondence we present a code construction procedure for obtaining 100% efficient codes with the fewest number of encoder states for all (M,d,∞) constraints with rational capacity. The decoders are sliding-block decoders with sliding window size d+1     

信息时代电磁兼容领域的挑战与应对(特邀文章)

论述了信息时代电磁兼容领域的挑战与应对策略.提出了信息社会安全的基础是网络与设备的电磁信息安全的理念;提出了电子设备不经意电磁发射引起的电磁信息漏泄的原理模型.分析了无处不在的电磁发射信息安全问题,综述了TEMPEST计算机研究的现状和发展趋势,论述了现代机器人、有线网络、无线网络以及工业网络的电磁信息安全问题.最后,展望了发展中的安全电磁兼容标准,阐述了现代工业和控制系统正在面临的越来越严重的信息攻击已经成为威胁国家关键基础设施的超级武器的国际动态.     

溴氰菊脂对蚯蚓超微结构影响的研究

杀虫剂在本世纪中叶以来得到了广泛的应用 ,并自人类发现一些杀虫剂在环境中的危害后 ,相继选用了一批低毒高效的杀虫剂在农业等领域中使用。其中 ,溴氰菊脂已大量地用于害虫的防治 ,溴氰菊脂是除虫菊脂类杀虫剂 ,可以有效地控制害虫 ,而不危害哺乳类和鸟类 ,且其在土壤中能很快的分解 ,无残留 ,对土壤微植物群落、微动物群落没有毒害作用。虽然溴氰菊脂对鱼类的毒性很强 ,但其在土壤中会很快的降解 ,同时其易被土壤的沉积物和有机物牢固地吸附而不易被冲洗进入水体危害鱼类。由于这些高效低毒 ,易降解及无残留的特点 ,使溴氰菊脂在目前广泛…     

Mechanisms of the origination of hypersegmented (hyperdiploid) neutrophils in rats as affected by cyclophosphamide

Feulgen cytophotometry has revealed tetraploid DNA content in some hypersegmented mature granulocytes in rat peripheral blood after two weeks of daily injections of cyclophosphamide (20 mg/kg of body weight). In bone marrow of rats which were given the preparation for 7 days myeloblasts, promyelocytes and myelocytes are blocked in G2 phase of the mitotic cycle. About 50% of metamyelocytes, bands and segmented granulocytes are also tetraploid. Thus cyclophosphamide has induced tetraploid hypersegmented neutrophils in rats as a result of maturation of G2 blocked proliferative pool granulocytes.     

电磁脉冲对大鼠肾上腺超微结构损伤的研究

目的 :本研究拟通过观察电磁脉冲 (EMP)辐照大鼠后其肾上腺组织学及超微结构的改变 ,初步探讨EMP致肾上腺损伤的特点。方法 :雄性二级Wistar大鼠 2 4只 ,随机分为 6组 ,每组 4只。其中 1组为对照组 ,其余 5组为辐照组。辐照组在高场强电磁脉冲模拟源下 ,以场强为 6× 10 4 V m ,脉冲上升时间为 2 0ns,脉宽为 30 μs的条件下 ,在2min内辐照大鼠 5次 ,对照组不做任何处理 ,辐照后于 1h、6h、12h、2 4h和 4 8h活杀动物 ,左侧肾上腺常规光镜制片 ,右侧肾上腺 4 %戊二醛及 1%锇酸双固定 ,Epon812包埋。LKB - 1180 0 (Pyramitome)半薄切片 ,定位后 ,LKB -Ⅴ型超薄切片机切片 ,乙酸铀和柠檬酸铅双染色 ,PHILIPS -CM12 0电镜下观察、拍片。结果 :辐射组大鼠肾上腺皮髓质细胞超微结构在 1h后即出现变化 ,且逐渐加重 ,包括皮质细胞内脂质颗粒及髓质细胞内的内分泌颗粒排空明显 ;细胞水肿 ,线粒体肿胀、空化、髓样体形成 ;内质网扩张 ;皮质细胞和毛细血管内皮细胞核异染色质边集 ,早期细胞凋亡表现 ;毛细血管内皮细胞线粒体的明显空化。结论 :EMP可引起大鼠肾上腺皮髓质细胞及毛细血管内皮细胞的损伤 ,并可诱导其凋亡的发生。细胞膜系统的损伤及应激反应可能参与了其超微结构损伤过程     

The Relation of Teratogenesis in Tenebrio Molitor to the Incidence of Low-Level Microwaves (Short Papers)

The teratogenic effects of irradiation by low-level microwaves have been studied using the pupae of the darkling beetle Tenebrio rnolitor. For exposures of 2-h duration, statistically significant increases in teratogenesis were observed at waveguide power levels down to 200 muW; the pupation time increased monotonically with the power. Exposures of various durations and powers at a constant dosage of 4 mW/h strongly suggested that it is the total dosage which determines the level of teratological damage.     

真空紫外MCP—PMT中应用碘化铯阴极的研究

简述了真空紫外ＭＣＰ－ＰＭＴ选择碘化铯做为阴极的依据，介绍了铬膜的透光性及碘化铯阴极的制作与阴极辐射灵敏度的测量，研制出整管，由此得出了相关的结论。     

通过用电信息采集系统开展反窃电工作中应注意的要点

随着经济的快速发展,人们对电气的依赖性越来越大,在人们广泛使用电力的过程中,也应运而生了许多的窃电违法行为。用电信息采集系统在反窃电工作中的应用可以有效的提高供电企业的反窃电工作效率。本文主要介绍应用用电信息采集系统开展反窃电工作时需要注意的要点。     

The Segmentation Method--An Approach to the Analysis of Microwave Planar Circuits (Short Papers)

In many practical planar circuitries, the circuit pattern can be divided into several segments which themselves have simpler shapes such as rectangles. The segmentation method proposed in this short paper is a method in which the characteristics of a planar circuit are computed by combining those of the segmented elements. It features a relatively short computer time required. The principle and computer algorithm are described. Finally, as an example, the application of the proposed method to the trial-and-error optimum design of a ladder-type 3-dB hybrid is described.     

CAF：电子工业小型化的威胁

概述了CAF的历史、发生的原理,分析了CAF产生的根本原因,比较了几种CAF失效分析的方法,同时也介绍了一种简易的测试设备。     

牛奶加工过程中的清洗(二)

五．牛奶厂的清洗。目前，牛奶厂采用的清洗方式主要是CIP清洗(Cleaning in place)，原地清洗或称定置清洗，即在基本不拆卸或挪动机械装置和管线的情况下对生产过程中能与牛奶发生接触的设备表面进行的清洗。其冲刷、清洗、灭菌的整个过程全部实现了自动化因此大大降低了劳动强度。而有一些不     

大气压行波激励N_2激光器

近年来,由于高速摄影、光化学反应的研究以及荧光测量等的需要,人们希望获得超短脉冲的相干光源.行波激励的高气压N_2激光器,其光脉冲的宽度主要由受激分子的弛豫时间所决定,与光在光腔中的传播时间无关,从而成为获得微微秒脉冲紫外光源的器件之一.     

The Method of Series Expansion in the Frequency Domain Applied to Multidielectric Transmission Lines (Short Papers)

In this short paper a method of expanding the phase constant and the field of a multidielectric transmission line as a power series of the frequency is developed. The method provides a theoretical justification for the widely used "static" approximations and indicates the reason why their accuracy is frequently good. This expansion may also be useful for estimating an upper limit to the frequency band in which the dispersion does not exceed a specified value. A numerical example is included.