Measurement of surface charges on the dielectric film based on field mills under the HVDC corona wire

The ion flow field on the ground is one of the significant parameters used to evaluate the electromagnetic environment of high voltage direct current (HVDC) power lines. HVDC lines may cross the greenhouses due to the restricted transmission corridors. Under the condition of ion flow field, the dielectric films on the greenhouses will be charged, and the electric fields in the greenhouses may exceed the limit value. Field mills are widely used to measure the groundlevel direct current electric fields under the HVDC power lines. In this paper, the charge inversion method is applied to calculate the surface charges on the dielectric film according to the measured ground-level electric fields. The advantages of hiding the field mill probes in the ground are studied. The charge inversion algorithm is optimized in order to decrease the impact of measurement errors. Based on the experimental results, the surface charge distribution on a piece of quadrate dielectric film under a HVDC corona wire is studied. The enhanced effect of dielectric film on ground-level electric field is obviously weakened with the increase of film height. Compared with the total electric field strengths, the normal components of film-free electric fields at the corresponding film-placed positions have a higher effect on surface charge accumulation.     

125 dtex/24×37 f海岛复合超细POY生产工艺探讨

研究了125 dtex/24×37 f海岛复合型POY的生产工艺。水溶性切片的预结晶温度为165℃、干燥温度120℃、干燥时间18 h、纺丝温度291℃、侧吹风风速0.4 m/s、纺丝速度2 800 m/m in,品质优良,满卷率可达到98%。     

用3DS MAX制作工程透视图

本文通过一步一步制作“张河湾抽水蓄能电站地下厂房”的三维图，来讲解3DS MAX的使用。通过阅读本文，使读者能很快掌握3DS MAX的工作过程，并能熟练使用这款大型的软件。     

Theoretical Study on Molecular Electrostatic Potential of C78

Density functional theory （DFT） was applied at the B3LYP/6-31G^＊ level to investigate the relative stability of the five fullerene isomers as well as the anions of C78. Full geometry optimization was carried out and distributions of electrostatic potential were calculated. The results showed that the C78（D3h′） cage was the most stable for C78^q-（ q = 2, 4, 6）, and the potential minimum Vmin（r） inside the sphere of C78（Dzh′） was the biggest one among the five isomers of C78. So C78（Dzh′） were electrons from the scandium atoms that were easier to accept than the other four isomers. On the other hand, MEP maps inside the sphere of C78（Dzh′） had three minima near the three vertexes. Each vertex was formed by the intersection of the three hexagons. Our results allowed a possible explanation for the bonding between the scandium atoms and the fullerene cage.     

两种不同酯化方法分析荞麦中脂肪酸成分

采用索氏提取法对荞麦油进行了提取,分别采用两种方法进行甲酯化处理,以气相色谱-质谱联用仪进行了分析,对脂肪酸组成和含量进行了比较。结果表明:两种酯化方法分别鉴定出8种脂肪酸,占荞麦油总量的98.64%和99.97%;方法1鉴定出的主要脂肪酸为:棕榈酸占脂肪酸总量的15.92%,亚油酸占脂肪酸总量的30.37%,油酸占脂肪酸总量的35.32%;方法2鉴定出的棕榈酸占脂肪酸总量的35.66%,亚油酸占脂肪酸总量的11.75%,油酸占脂肪酸总量的33.26%。     

黄瓜霜霉病的发生规律及综合防治措施

经过3年的调查研究，明确了保护地内黄瓜霜霉病的发生规律，在此基础上，提出了以培育壮苗，增施有机肥，适时叶面追肥，适时灌水，科学放风为主，药物保护为辅的综合防治措施，该套措施能有效地控制黄瓜霜霉病的危害，很受农民的欢迎。     

3G-ALE系统突发波形的软判决译码算法

第三代短波自动链路建立系统(3G-ALE)的发送波形采用了多进制正交扩频和截尾卷积码技术。将比特软值提取值算法与环绕Viterbi算法(WAVA)相结合,将正交扩频解调的比特软值用于WAVA译码算法,从而改进了3G-ALE系统译码算法。仿真结果表明,新的译码算法与传统的硬判决算法相比性能有较大提高,在误帧率为10-2时性能在传统算法基础上提高了2.2dB。     

入侵诱骗系统应用技术研究

随着计算机和网络技术的迅速发展,针对网络和计算机系统的攻击也屡见不鲜,网络安全问题变得日益严峻.本文提出的人侵诱骗系统,在保证网络安全的情况下,增加对新的攻击方法的了解,变被动防御为主动进攻,使其具有主动交互性,勾画出了一种新的网络安全防御策略.     

φ3600×6000mm溢流型球磨机出料端盖裂缝修复

通过对φ3600×6 000mm溢流型球磨机出料端盖母材ZG35焊接性能和机械性能的详细分析,确定了焊接的可行性。选择了相应的焊条,制定了焊接工艺,取得了良好效果。     

黄瓜霜霉病的发生规律及综合防治措施

经过3年的调查研究,明确了保护地内黄瓜霜霉病的发生规律,在此基础上,提出了以培育壮苗,增施有机肥.适时叶面追肥,适时灌水,科学放风为主,药物保护为辅的综合防治措施,该套措施能有效地控制黄瓜霜霉病的危害,很受农民的欢迎。