STN7 Kinase Is Essential for Arabidopsis thaliana Fitness under Prolonged Darkness but Not under Dark-Chilling Conditions

Reversible phosphorylation of photosystem II light harvesting complexes (LHCII) is a well-established protective mechanism enabling efficient response to changing light conditions. However, changes in LHCII phosphorylation were also observed in response to abiotic stress regardless of photoperiod. This study aimed to investigate the impact of dark-chilling on LHCII phosphorylation pattern in chilling-tolerant Arabidopsis thaliana and to check whether the disturbed LHCII phosphorylation process will impact the response of Arabidopsis to the dark-chilling conditions. We analyzed the pattern of LHCII phosphorylation, the organization of chlorophyll–protein complexes, and the level of chilling tolerance by combining biochemical and spectroscopy techniques under dark-chilling and dark conditions in Arabidopsis mutants with disrupted LHCII phosphorylation. Our results show that during dark-chilling, LHCII phosphorylation decreased in all examined plant lines and that no significant differences in dark-chilling response were registered in tested lines. Interestingly, after 24 h of darkness, a high increase in LHCII phosphorylation was observed, co-occurring with a significant F_V/F_M parameter decrease. The highest drop of F_V/F_M was detected in the stn7-1 line–mutant, where the LHCII is not phosphorylated, due to the lack of STN7 kinase. Our results imply that STN7 kinase activity is important for mitigating the adverse effects of prolonged darkness.     

一种改进的异步电机弱磁控制方法

针对机床用异步电机要求低速时能输出较大转矩且在高速运行时响应速度快的特点,在转子磁场定向的矢量控制方法的基础上,提出一种考虑定子电压的电压闭环弱磁控制策略,实现了励磁电流和输出电压的动态调节,解决了传统方法下电机带负载能力和高速运行响应速度不可兼得的矛盾。试验结果验证了该方法的可行性和有效性。     

影响电网安全运行的各类故障及其相应对策

在统计分析了近10年来全国电网运行各类故障的基础上,对当前电网事故发生的特点和规律进行了分析总结,指出了制约电网安全运行的主要因素,并提出了相应的对策。     

论冲压模具定置摆放

重点介绍了汽车冷冲压模具因摆放不合理而存在的安全隐患和发生的工装事故,以及采用工装定置摆放后产生的经济效益和管理价值。     

Structural, magnetic and dielectric properties of La2−xCaxNiO4+δ (x = 0, 0.1, 0.2, 0.3)

The synthesis, structural, magnetic and dielectric properties of a new type of high permittivity materials La_2−xCa_xNiO_4+δ (x = 0, 0.1, 0.2, 0.3) (abbreviated as LCNs) were reported. The samples were prepared through conventional solid state reaction route. Detailed structural information was retrieved by Rietveld refinement; normalized bond length and bond valence was calculated to investigate the compression/dilation effect of bonds and atoms in unit cell. It can be found all samples belong to K₂NiF₄ structure with space group I4/mmm. Doping of Ca in La₂NiO_4+δ shrinks the unit cell and makes the structure tend to become instable. Three types of (La, Ca)-O bonds, and two kinds of Ni-O bonds exist in LCNs. Along c axis there are alternately compressed (La,Ca)O₉ dodecahedra and lengthened NiO₆ octahedra. Room temperature magnetic measurements show that the materials are paramagnetic and Ca doping can improve the spontaneous magnetization. Furthermore, all samples have colossal values of the dielectric constant (?) at frequencies lower than 1 kHz. Interestingly, La_1.8Ca_0.2NiO_4+δ maintains its high permittivity at frequencies up to 1 MHz while La_1.7Ca_0.3NiO_4+δ has the lowest dielectric loss (tan δ). Calcium doping can effectively enhance ? and inhibit tan δ. The distortion of (La,Ca)O₉ dodecahedra can well explain their dielectric properties.     

指向标识设置间距及设置位置对路效率影响的虚拟研究

为研究在有岔道口的通道上标识设置对行人寻路效率的影响,本文利用Quest3D软件构建虚拟空间,在虚拟空间中对上述问题展开实验研究.通过分组实验的方式,让不同组的实验者在不同标识设置参数的虚拟空间中行走,并采集实验者的实验数据,实验数据显示当标识间距大于50m时或者标识缺失而不远处有类似标识影响时寻路效率会明显下降.因此在有岔道口的通道上标识的设置距离应当小于50m,同时合理设置标识位置,防止与寻路无关的类似标识进入行人视线.     

The Titanic sunk,so what? Project manager response to unexpected events

Projects are inherently uncertain and face unexpected events, from small changes in scope to unforeseen client’s bankruptcy. This paper studies how project managers respond to such events and how successful and unsuccessful responses differ from the perspective of the practitioner. We analysed 44 unexpected events faced by 22 experienced project managers in defence and defence-related organisations. The project managers compared two unexpected events that they faced, one that they considered the response successful and the other unsuccessful. We identified three pillars supporting successful responses to unexpected events: (1) responsive and functioning structure at the organisational level, (2) good interpersonal relationship at the group level and (3) competent people at the individual level. The events and respective responses analysed suggest that improvement in project management can be achieved by better managing these three pillars, allowing project and programme managers to “create their own luck”.     

油浸式电力变压器固体绝缘老化检测技术的应用

由于固体绝缘具有不可恢复的老化特性,其性能状态对变压器的运行寿命及维护策略有着重要的影响。本文分析了影响固体绝缘老化的各种因素以及目前诊断方法的优缺点,重点阐述了极化去极化电流法和恢复电压法,二者从变压器绝缘系统的电路模型入手,以介质响应理论为基础,通过极化特性曲线和相关参数的分析得到变压器固体绝缘状态的可靠信息。现场试验数据表明了测量结果与聚合度、糠醛分析法的一致性,因此介质响应分析法可以作为一条简单有效的途径实现变压器固体绝缘性能的无损检测,建议在电力设备运行维护单位广泛开展。     

智能交通灯控制器的设计

现代社会对交通运输日趋依赖,传统的交通灯控制系统已经表现出明显的缺点：红绿灯时间相对固定,不能随车流量的改变而调整红绿灯的显示时间。基于上述原因,设计了一种简易的智能交通灯控制器系统。首先介绍了交通灯控制系统的设计方案,以单片机AT89S51芯片为中心来实现智能控制;接着用汇编语言在Keil环境下进行编程调试,通过软件Protues实现硬件仿真,最后将软件系统与硬件联调,实现了以下功能：绿灯时间可检测车流量并可通过双位数码管显示,能根据实际车流量自动设置红绿灯燃亮时间;红绿灯循环点亮,倒计时5s时黄灯闪烁警示;车辆闯红灯报警。该控制器系统在很大程度上缓解了交通压力,解决了繁华道路交通堵塞等情况。     

纳米改性变压器油-纸复合绝缘频率响应特性

为寻求提高变压器油纸复合绝缘特性可能途径,开展了纳米改性变压器油-纸复合绝缘频率响应特性研究。利用电介质频率响应法,对比测试了添加纳米改性前后油纸复合绝缘不同微水含量、在不同温度条件下,10^-4～10^-6Hz范围频率响应;建立基于Cole-Cole函数的弛豫模型分析实验结果,并通过最小二乘法拟合得到弛豫模型参数;分析小同微水含量及温度条件下添加纳米粒子对弛豫参数的影响。结果表明：所建立的弛豫模型能较好地反映油纸复合绝缘频率响应特性,弛豫模型参数能反映油纸复合绝缘状态的变化规律;添加纳米粒子引入了新弛豫机制,在低频及高频段,降低了油纸复合绝缘的介质损耗,在0．1～100Hz频率范围内却增大了其介质损耗,且随着温度升高及微水含量增加,影响越显著。