Effects of lighting and air movement on temperatures in reproductive organs of plants in a closed plant growth facility

Temperature increases in plant reproductive organs such as anthers and stigmas could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions without adequately controlled environments in closed plant growth facilities. There is a possibility such a situation could occur in Bioregenerative Life Support Systems under microgravity conditions in space because there will be little natural convective or thermal mixing. This study was conducted to determine the temperature of the plant reproductive organs as affected by illumination and air movement under normal gravitational forces on the earth and to make an estimation of the temperature increase in reproductive organs in closed plant growth facilities under microgravity in space. Thermal images of reproductive organs of rice and strawberry were captured using infrared thermography at air temperatures of 10–11 °C. Compared to the air temperature, temperatures of petals, stigmas and anthers of strawberry increased by 24, 22 and 14 °C, respectively, after 5 min of lighting at an irradiance of 160 W m⁻² from incandescent lamps. Temperatures of reproductive organs and leaves of strawberry were significantly higher than those of rice. The temperatures of petals, stigmas, anthers and leaves of strawberry decreased by 13, 12, 13 and 14 °C, respectively, when the air velocity was increased from 0.1 to 1.0 ms⁻¹. These results show that air movement is necessary to reduce the temperatures of plant reproductive organs in plant growth facilities.     

基于星上实时信号处理机的Chirp Scaling算法实现方法

基于改进的Chirp Scaling算法,提出了一种适用于星上实时信号处理机的高效成像处理实现方法,其核心思想也可应用于其它高分辨率星载SAR的精确成像算法.首先介绍了实时信号处理机的结构,分析了数据处理粒度及其并行流水处理结构.在此基础上,针对单个粒度的成像处理重新设计了算法流程,提出了一种高效的实现方法.利用实时信号处理机,对仿真的回波数据进行了成像处理实验,结果表明:在41?s内能够完成成像处理,成像处理速度和图像质量满足系统设计要求,从而验证了该方法的有效性.     

The decision to develop the Space Shuttle

Many of the problems that the Space Shuttle programme has had in meeting its goals of routine and cost-effective access to space can be traced to various characteristics of the decision to develop the Space Shuttle. That decision was made through a process of bureaucratic politics, with little attention given to future users of the Shuttle. The design chosen for development was a poor compromise between demanding Pentagon and NASA requirements and a limited budget.     

人工智能产生式系统的分析(下)

本文分为四节:一、产生式系统的求解方式;二、问题描述的不同表示法;三、规则集的灵活性和规格化;四、控制策略。全文分上、下篇发表,上篇为第一、二、三节,发表于本刊1986年第2期,本期发表第四节,即下篇。     

用于大机动飞行仿真的宽频带高速三轴转台

为满足一种新型大机动飞行器飞行姿态半物理仿真的要求,采用变增益液压伺服机构和变系数前馈补偿器等技术,对某三轴液压飞行仿真转台进行了改型研制。在转台具有良好低速特性的同时,其大振幅下的频宽和高速响应特性达到了国际同类转台的水平。所研究实施的技术方案,对研制新转台及旧有转台的技术改造都有参考价值。     

Dynamics of stellar systems: Violent relaxation and gravothermal catastrophe

The gravitational evolution of stellar systems exhibit collective and collisional effects. Collective effects (Violent Relaxation) seems to be unefficient to create any structure or to relax the distribution function. Gravothermal Catastrophe is shown to be a real instability driven by collisions, but its time scale is very long compared to astrophysical times. It is suggested that intermediate range perturbations may modify these conclusions.     

“机械设计”课程设计的新课题

本文根据航空发动机和动力传动系统减速器的特点,提出了常用的NGW型行星减速器设计是“机械设计”课程设计的最佳题目。扼要分析了其计算特点和结构特点,并给出了设计题目及部分原始数据以供参考。     

长空高机动靶机燃油系统试验研究

本文主要介绍长空无人机高机动靶机燃油系统各阶段试验原理、试验内容、试验方法,以及对试验结果的讨论。一系列试验证明了高机动靶机燃油系统的可行性、可靠性和适用性。     

位置伺服滑态控制系统的单片机实现

本文以MCS-51(8031)为基础研究了位置伺服的滑态控制(Sliding Mode Control,简称为SMC)系统的实现。提出了SMC律的设计方法,给出了8031 SMC控制器的硬软件的设计方法与技巧,并在8031 SMC控制器上作了模数混合仿真,给出了仿真结果。     

遥外测综合测量系统弹道计算新方法

遥外测综合测量系统在定位精度上有其局限性 ,布站不能接近同一平面 ,必须布置一个空中站来改善布站几何 ,否则容易引起定位无解或精度差 ,但布置空中站在工程上很难实现 ,且代价太高。针对这个问题 ,提出一种新的弹道计算方法 ,可以有效弥补上述局限性 ,取消空中站 ,并且显著提高定位精度。