实施精益生产方式的有效性

精益生产方式源于日本丰田公司,它是运用多种管理方法、手段对生产过程中的"人、机、料、法、环"诸要素进行组合,做到以必要的劳动确保必要的时间内,按必要的数量,生产必要的零部件,以期达到杜绝超量生产,消除无效劳动,降低成本,提高质量,用最少的投入实现最大产出的一种先进的生产方式.     

电弧焊的省力化,自动化：焊接自动化的特征及发展要点

焊接省力化、自动化之所以是必要的,那是因为要充分地适应必要的、满意的质量的产品生产,而且向经济的方面发展。 焊接自动化的着眼点主要集中在下述三点： ①生产的稳定，高效率； ②确保产品质景的稳定和提高； ③降低焊接成本。 当然，作为焊接省力化、自动化的目标，还要考虑下述附带因素： ①改善生产环境； ②保证操作的安全性； ③适应熟练工人的不足； ④适应劳动力质的变化（操作者的高龄化、高学历化）。 这些附带因素可根据不同场合作为自动化的主要着眼点。特别是随着“机器人”的发展， 更应作为着眼点。 本文对电弧焊的省力化、自动化发展方向，相应各阶段的水平，对其性能、机构的特点 进行整理和归纳，同时对其机械化、自动化的发展要点，概略加以说明．以供参考。     

精益生产与产品可靠性

精益生产(Lean production)是一种优越的制造产品的管理方式，是世界级制造技术的核心，它将成为21世纪制造业的标准生产方式。本文通过对精益生产方式的概念、特点和其中准时化生产、拉动系统、看板管理、零库存等有关内容的详细阐述，分析了精益生产方式与产品可靠性的密切关系，说明推行精益生产方式是一种非常好的提高产品可靠性的管理方法。根据国防武器装备的特点，推行精益生产方式尤其必要。文章最后介绍了当前国内外推行精益生产方式的情况。     

C-103铌合金可延伸喷管成形工艺及冷展试验

本文简单介绍可延伸喷管的特点及C-103铌合金的性能,着重论说该喷管中型冷试件采用强力旋压-延伸成形-模胎扩径的成形工艺,并对喷管的冷展试验进行了分析比较,从而为可延伸喷管的初样生产提供必要的技术数据。     

供热通风与空调工程专业《建筑概论》课程教学的思考

文章通过分析高职高专供热通风与空调工程专业《建筑概论》课程教学中存在的问题,提出通过改革教材来更好地突出学习重点,采用合理的教学方式方法来提高学生的学习兴趣,改变原有的考核方式以准确考察学生的学习效果,达到高职高专教育要培养具有必要的理论知识和较强实践能力的生产、建设、管理和服务的一线专门人才的目的。     

自动驾驶仪系统温度补偿

为了解决自动驾驶仪系统在研制生产中,由于有些元件的传递系数温度漂移较大,而造成系统处于极限环境温度时传递系数超差的问题,根据现有元件的实际水平,通过元件在常温、低温、高温试验时所测量的传递系数数据,从系统分析角度出发,采用统计分析方法找出回路传递系数温度漂移的系统误差与随机误差,并对系统误差进行必要的补偿来提高系统的温度稳定性。     

计算机模拟在铸钢后桥工艺优化中的应用

介绍了View Cast软件在铸钢后桥工艺优化中的应用,利用View Cast软件强大的设计计算功能设计计算了后桥的浇注系统(包括浇注系统的尺寸、冒口数目及尺寸),并在必要部位安放冷铁,通过模拟计算,验证了该工艺设计的可行性。实践表明,改进后的工艺有效地解决了试制过程中出现的缺陷问题,提高了铸件的质量,实现了批量化生产。     

用太阳辐射波检测调试卫星地面站天线

建立成套卫星地面站天线和馈源质量监测手段，对卫星地面站研制生产单位是很必要的。现型仪器设备的购置和微波暗室的建立要消耗高额资金，给若干单位造成了困难。利用太阳辐射波作源信号，再配备一套简易微波场强测量仪的检测、调试卫星地面站天馈系统组装质量方案，其实施、使用方便，可供有关单位借鉴和参考。     

VAISALA湿度传感器的故障检测与诊断

VAISALA公司生产的自动观测系统在民航系统应用很广,该系统对稳定度和准确性的要求很高。作为系统中非常关键的元件——传感器,一旦出现故障将直接影响整个系统的结果输出。因此,针对传感器的故障检测与诊断研究是很有必要的。本文通过对成都2005年9月一次湿度传感器故障的检测     

高可靠超小型塑封整流二极管

目前有两种超小型塑封二极管,正以其优越使用性能取代着2CZ(或2CP)同类产品,应用前景十分可观,但此情况还未引起使用单位广泛注意,在这里确有介绍一下的必要。这两种二极管就是北京无线电四厂生产的1安1N4000系列和3安1N5400系列两类产品。它的特点是:     

System design and performance of the two-gyro science mode for the Hubble Space Telescope

For 15 years, the science mission of the Hubble Space Telescope (HST) required using three of the six on-board rate gyros for attitude control. Failed gyros were eventually replaced through Space Shuttle Servicing Missions. To ensure the maximum science mission life, a two-gyro science (TGS) mode has been designed and implemented with performance comparable to three-gyro operations. The excellent performance has enabled a transition to operations with 2 gyros (by intentionally turning off a running gyro to save it for later use), and allows for an even greater science mission extension. Predictions show the gain in mission life approaching two years. In TGS mode, the rate information formerly provided by the third gyro is provided by another sensor. There are three submodes, each defined by the sensor used to provide the missing rate information (magnetometers, star trackers, and fine guidance sensors). Although each sensor has limitations, when used sequentially they provide the means to transition from relatively large, post-maneuver attitude errors of up to 10, to the arcsecond errors needed to transition to fine pointing required for science observing. Only small reductions in science productivity exist in TGS mode primarily due to more difficult target scheduling necessary to satisfy constraints imposed by the use of the star trackers. Scientists see no degradation in image quality due to the very low jitters levels that are nearly equivalent to three-gyro mode.     

基于噪声子空间估计的MWF实现

采用阵列天线对GPS接收信号进行干扰抑制,在信号处理时引入时延,形成空时二维处理的模式.空时二维抗干扰由于运算量大而导致在实际实现困难,必须进行降维处理.多级维纳滤波(MWF)方法可以有效降低滤波器的维数,但是经典的MWF方法存在子空间维数估计不准的问题.本文对于多级维纳滤波方法进行了分析,利用MWF的分析滤波器将接收信号矢量映射为另一信号矢量.通过对该信号矢量的协方差矩阵进行分析,找到一种判断子空间维数的稳健方法.仿真表明该方法能够准确地估计出噪声子空间维数.与传统的设定MSE门限的方法相比较,得出用本方法估计子空间维数更为准确可靠,抗干扰性能更优的结论.     

A perspective on the importance of reproductive mode in astrobiology

Reproduction is a vital characteristic of life, and sex is the most common reproductive mode in the eukaryotic world. Sex and reproduction are not necessarily linked mechanisms: Sexuality without reproduction exists, while several forms of asexual reproduction are known. The occurrence of sexuality itself is paradoxical, as it is very costly in evolutionary terms. Most of the hypotheses (more than 20) attempting to explain the prevalence of sex fall into two categories: Sex either creates good gene combinations for adaptation to environments or eliminates bad gene combinations counteracting the accumulation of mutations. In spite of this apparent wealth of beneficial effects of sex, asexuality is not rare. Most eukaryotic, asexual lineages are short-lived and can only persist through the presence of sexual roots, but at least two animal groups, bdelloid rotifers and darwinulid ostracods, seem to claim the status of ancient asexuals. Research on (a)sexuality is relevant to astrobiology in a number of ways. First, strong relationships between the origin and persistence of life in extreme environments and reproductive mode are known. Second, the "habitability" of nonterrestrial environments to life greatly depends on reproductive mode. Whereas asexuals can do equally well or better in harsh environments, they fail to adapt fast enough to changing abiotic and biotic environments. Third, it has been shown that plants reproduce mainly asexually in space, and sperm production and motility in some vertebrates are hampered. Both findings indicate that extraterrestrial life under conditions different from Earth might be dominated by asexual reproduction. Finally, for exchange of biological material between planets, the choice of reproductive mode will be important.     

提高竞争力 推动军工企业管理模式创新

通过介绍目前军工制造企业特点,提出军工制造企业管理模式必须得到创新。针对管理模式创新的原则,并分析目前面临问题,阐述了创新的途径和策略,为军工制造企业管理模式的创新提供了借鉴。     

Metabolic assessments during extra-vehicular activity

Extra-vehicular activity (EVA) has a significant role during extended space flights. It demonstrates that humans can survive and perform useful work outside the Orbital Space Stations (OSS) while wearing protective space suits (SS). When the International Space Station 'Alpha' (ISSA) is fully operational, EVA assembly, installation, maintenance and repair operations will become an everyday repetitive work activity in space. It needs new ergonomic evaluation of the work/rest schedule for an increasing of the labor amount per EVA hour. The metabolism assessment is a helpful method to control the productivity of the EVA astronaut and to optimize the work/rest regime. Three following methods were used in Russia to estimate real-time metabolic rates during EVA: 1. Oxygen consumption, computed from the pressure drop in a high pressure bottle per unit time (with actual thermodynamic oxygen properties under high pressure and oxygen leakage taken into account). 2. Carbon dioxide production, computed from CO2 concentration at the contaminant control cartridge and gas flow rate in the life support subsystem closed loop (nominal mode) or gas leakage in the SS open loop (emergency mode). 3. Heat removal, computed from the difference between the temperatures of coolant water or gas and its flow rate in a unit of time (with assumed humidity and wet oxygen state taken into account). Comparison of heat removal values with metabolic rates enables us to determine the thermal balance during an operative medical control of EVA at "Salyut-6", "Salyut-7" and "Mir" OSS. Complex analysis of metabolism, body temperature and heat rate supports a differential diagnosis between emotional and thermal components of stress during EVA. It gives a prognosis of human homeostasis during EVA. Available information has been acquired into an EVA data base which is an effective tool for ergonomical optimization.     

SPECTRA高性能轻型降落伞织物

织物件的好坏在很大程度上取决于纤维性能和纱线品质,纤维性能越优织出来的织物肯定就越好。就降落伞织物来说,质轻,高强、耐磨、耐环境变化是选材时必须考虑的因素。其中重量轻、强度高更是最引人注目的要求。目前市场上已有多种纤维具备上述特点,但迄今还未发现优于SPECTRA(美国ALLIED-SIGNAL公司商标名)的纤维。用SPECTRA材料制造的降落伞,与现有降落伞相比,在重量、强度和抗化学性方面要优越得多。     

基于FPGA实现的SAR成像中的方位预滤波

针对SAR成像中的方位预滤波,讨论两种方位预滤波的算法。经比较,“拉格朗日乘子法”滤波器更适合应用到SAR成像中,因为该方法在保证相位特性的同时使成像带宽内信号能量最大、非成像带宽内的信号能量尽可能小,最大限度地保证了成像质量。最后还给出方位预滤波基于FPGA的硬件实现及实测数据成像结果。     

Effect on the cardiac function of repeated LBNP during a 1-month head down tilt

Cardiovascular assessment by ultrasound methods was performed during two long duration (1 month) Head Down Tilt (HDT) on 6 healthy volunteers. On a first 1 month HDT session, 3 of the 6 subjects (A, B, C) had daily several lower body negative pressure tests (LBNP), whereas the 3 subjects remaining (D, E, F) rested without LBNP. On a second 1 month HDT session subjects D, E, and F had daily LBNP tests and the A, B and C subjects did not. The cardiac function was assessed by Echocardiography, (B mode, TM mode). On all the "6 non LBNP" subjects the left ventricule diastolic volume (LVDV), the stroke volume (SV) and the cardiac output (CO) increase (+10%, -15%) after HDT then decrease and remain inferior (-5%, -5%) or equal to the basal value during the HDT. Immediately after the end of the HDT the heart rate (HR) increase (+10%, +30%) whereas the cardiac parameters decrease weakly (-5%, -10%) and normalize after 3 days of recovery. On the "6 LBNP" subjects the LVDV, SV and CO increase (+10%, 15%) after 1 h HDT as in the previous group then decrease but remain superior (+5%, +15%) or equal to the basal value. After the HDT session, the HR is markedly increased (+20%, +40%) the LVDV and SV decrease (-15%, -20%) whereas the CO increases or decreases depending on the amplitude of the HR variations. These parameters do not completely normalize after 3 day's recovery. Repeated LBNP sessions have a significant effect on the cardiovascular function as it maintains all cardiac parameters above the basal value. The LBNP manoeuvre can be considered as an efficient countermeasure to prevent cardiac disadaptation induced by HDT position and probably microgravity.     

生产关系就是分配关系

在马克思的著作中对生产关系的论述本来是清楚的、明确的，牛产关系和分配关系是不可分割的统一体，它们构成了一定社会的生产方式。把生产关系定义为三因素的观点是理论开倒车的行为。