机载设备电压尖峰试验测试标准分析

RTCA/DO-160F、GJB151A/152A-97和GJB181-86都涉及了电压尖峰（或电源线尖峰信号传导敏感度）试验项目。在对设备电源部分性能的考核中,电压尖峰（或电源线尖峰信号传导敏感度）试验是重点验证项目。比较分析这三个标准对该项目在测试条件、测试对象和测试方法上的差异,对于机载设备的电压尖峰（或电源线尖峰信号传导敏感度）试验,由于这三个标准的使用范围和适用对象不同,其要求也不尽相同。RTCA/DO-160F根据设备使用场合的保护等级不同而将设备进行分类,要求较为灵活;GJB151A/152A-97则主要是针对机载设备的使用平台提出要求,是军用机载设备基础性的要求;而GJB181-86则主要适用于飞机供电系统与用电设备之间的协调,针对性强,要求较高。     

砂尘试验军用标准的方法探讨

对GJB 150.12-1986《军用设备环境试验方法砂尘试验》、GJB 150.12A-2009《军用装备实验室环境试验方法第12部分:砂尘试验》和RTCA/DO-160E《机载设备的环境条件和测试过程》进行了详尽的对比,分析了不同砂尘试验的操作技术,提出了必须严格控制砂尘试验条件和过程的建议,并表达了砂尘试验不同标准或不同的试验程序结果不能进行比较的观点。     

温度环境试验及其标准综述（二）典型温度试验程序

温度试验一般包括高、低温贮存试验,高、低温工作和短时工作试验,温度冲击试验和温度变化试验。GJB 150/150A、HB 6167/6167A、GB/T 2423等系列环境试验标准中的主要温度试验程序如表1所示。上述三个系列标准对应的国外标准是810C/810F,RTCA DO160B/160F和IEC 68号出版物。表1中还说明了各种试验程序的目的和模拟的环境。     

基于不同标准爆炸性大气试验程序对比分析

本文基于GJB 150.13A-2009、GJB 150.13-1986、RTCA/D O160G-2010(第九章)对爆炸性大气试验方法中"在爆炸性大气中工作"试验程序进行了对比分析,分析了不同标准对试验设备、试验参数及实施程序上的要求与区别,并对标准实施方法进行了明确与分析,可为后续开展机载设备爆炸性大气试验提供参考与指导。     

可靠性与环境适应性标准表

标准 标准号 标准名称 1 GJB 1 172一91 军用设备气侯极值 2 GB/T 19000.3一94 质量管理和质量保证标准第三部分:GB/T19001一1509001 在软件开发、供应和维护中的使用指南 3 GJB 150.5一86 军用设备环境试验方法温度冲击试验 4 GJB 150.6一86 军用设备环境试验方法温度一高度试验 5 GJB 1 50.7一86 军用设备环境试验方法太阳辐射试验 6 GJB 150.8一86 军用设备环境试验方法淋雨试验 7 GJB 150.9一86 军用设备环境试验方法湿热试验 8 GJB 150.10一86 军用设备环境试验方法霉菌试验 9 GJB 150.11一86 军用设备环境试验方法盐雾试…     

军用整车道路行驶可靠性试验方法研究

军用整车为了验证是否达到研制总要求规定的可靠性指标要求,通常需要进行道路行驶可靠性试验,平均故障间隔里程(MMBF)是整车道路行驶可靠性试验传统的主要评价指标。本文研究一种选用GJB 899A-2009《可靠性鉴定和验收试验》中的定时截尾的可靠性鉴定试验方案进行军用整车道路行驶可靠性的新试验方法,相比传统道路行驶可靠性试验方法,使用GJB 899A-2009定时截尾方法对军用整车进行道路行驶可靠性考核,可以事先规定试验结束时间,MTBF值可客观体现车辆的固有可靠性,且通过对试验数据计算可以得出整车的可靠性水平。但该方法仍存在不足,需要对相关标准进行完善。     

轨道交通电连接器国内环境试验标准分析

铁路作为国民经济大动脉、国家重要基础设施和大众化交通工具,在国民经济和社会生活中的作用至关重要。电连接器是铁路车辆设备的关键器件之一,有着很高的安全性和可靠性要求。着重分析了轨道交通电连接器标准中的电性能、机械性能和环境适应性的试验方法,并对这些标准进行了对比总结。经分析发现,更新版本的标准比被替换的标准增加了试验项目,细化了试验条件。然而,目前国内轨道交通电连接器的标准版本相对落后,仅GB/T 25022和GB/T 25023为2010年发布实施。亟需新的标准或试验方法以指导轨道交通电连接器的质量检测和认证。     

GJB 367A和GJB 150.8A对于小尺寸设备淋雨试验要求的对比研究

为了深入理解淋雨试验的国家军用标准,为了正确制定小尺寸室外设备的淋雨试验大纲,对GJB150.8A-2009和GJB361A-2001中的淋雨试验条件、试验方法、试验判据进行对比、研究和总结,并分析出标准中未明确说明的试验要求,有助于提高淋雨试验的可操作性和试验结论准确性。     

机载设备气候类环境试验标准分析

基于机载设备在运输、存贮和使用工作中的环境条件,军用标准GJB 150和民用标准DO-160、HB 6167和HB5830均对其给出了试验规范和要求,试验项目主要分为力学类、气候类、电磁类和综合环境类。针对气候类试验,从军用标准和民用标准两个角度对其进行对比分析,最后针对分析结果进行了归纳总结,得出各个标准之间的差别和共同点,为机载设备气候类试验标准及测试方法的选取提供参考意见。     

霉菌试验标准的方法探讨

对GJB 150.10-1986《军用设备环境试验方法霉菌试验》、GJB 150.10A-2009《军用装备实验室环境试验方法第10部分:霉菌试验》、和GB 2423.16-2008《电工电子产品环境试验第2部分:试验方法试验J及导则:长霉》进行了详尽的对比,分析了不同霉菌试验的操作技术,提出了必须严格控制霉菌试验条件和过程的建议,并表达了霉菌试验不同标准或不同的试验程序结果不能进行比较的观点。     

Conversion of temperate forests into heaths: Role of ecosystem disturbance and ericaceous plants

Fire and logging in nutrient-poor temperate forests with certain ericaceous understory plants may convert the forests into heaths. The process of disturbance-induced heath formation is documented by using examples ofCalluna in western Europe,Kalmia in Newfoundland, andGaultheria (salal) in coastal British Columbia. In a cool, temperate climate, rapid vegetative growth ofCalluna, Kalmia, and salal following disturbance results in increasing organic accumulation (paludification), nutrient sequestration, soil acidification, and allelochemicals. These are thought to be the main reasons to conifer regeneration failure in disturbed habitats. If continuation in forest is a land-use objective, then temperate forests with an ericaceous understory should not be logged unless effective silvicultural methods are devised to control the ericaceous plants and restore forest regeneration. Preharvest vegetation control may be considered as an option. Failure to control the understory plants may lead to a long-term vegetation shift, from forest to heathland, particularly in nutrient-poor sites. Successful methods of controllingKalmia andGaultheria, however, have yet to be developed. While theKalmia- andGaultheria- dominated heathlands are undesirable in Canada and the Pacific Northwest, a wide range ofCalluna heathlands of western Europe are being conserved as natural and seminatural vegetation.     

Urban ecological systems: scientific foundations and a decade of progress

Urban ecological studies, including focus on cities, suburbs, and exurbs, while having deep roots in the early to mid 20th century, have burgeoned in the last several decades. We use the state factor approach to highlight the role of important aspects of climate, substrate, organisms, relief, and time in differentiating urban from non-urban areas, and for determining heterogeneity within spatially extensive metropolitan areas. In addition to reviewing key findings relevant to each state factor, we note the emergence of tentative "urban syndromes" concerning soils, streams, wildlife and plants, and homogenization of certain ecosystem functions, such as soil organic carbon dynamics. We note the utility of the ecosystem approach, the human ecosystem framework, and watersheds as integrative tools to tie information about multiple state factors together. The organismal component of urban complexes includes the social organization of the human population, and we review key modes by which human populations within urban areas are differentiated, and how such differentiation affects environmentally relevant actions. Emerging syntheses in land change science and ecological urban design are also summarized. The multifaceted frameworks and the growing urban knowledge base do however identify some pressing research needs.     

Neighbourhood characteristics and urban gardens in the Toledo metropolitan area: staffing and voluntarism,food production,infrastructure, and sustainability practices

Urban gardens are important sources of sustenance for communities with limited access to food. Hence, this study focuses on food production in gardens in the Toledo metropolitan area in Northwest Ohio. We administered surveys to 150 garden managers from November 2014 to February 2015 in our attempt to better understand how neighbourhood racial composition and poverty levels are related to staffing and voluntarism, food production and distribution, the development of infrastructure, and the adoption of sustainability practices in urban gardens. The results from 30 gardens are presented in this paper. We used Geographic Information Systems to map the gardens and overlay the map with 2010 census data so that we could conduct demographic analyses of the neighbourhoods in which the gardens were located. Though the gardens were small – two acres or less – up to 46 varieties of food were grown in a single garden. Gardens also operated on small budgets. Food from the gardens was gifted or shared with friends, family, and neighbourhood residents. Gardens in predominantly minority neighbourhoods tended to have fewer institutional partners, less garden infrastructure, and had adopted fewer sustainable practices than gardens in predominantly White neighbourhoods. Nonetheless, residents of predominantly minority and high-poverty neighbourhoods participated in garden activities and influenced garden operations. Volunteering and staffing were racialised and gendered.     

Predicting deer-vehicle collisions in an urban area

Collisions with deer and other large animals are increasing, and the resulting economic costs and risks to public safety have made mitigation measures a priority for both city and wildlife managers. We created landscape models to describe and predict deer-vehicle collision (DVCs) within the City of Edmonton, Alberta. Models based on roadside characteristics revealed that DVCs occurred frequently where roadside vegetation was both denser and more diverse, and that DVCs were more likely to occur when the groomed width of roadside right-of-ways was smaller. No DVCs occurred where the width of the vegetation-free or manicured roadside buffer was greater than 40 m. Landscape-based models showed that DVCs were more likely in more heterogeneous landscapes where road densities were lower and speed limits were higher, and where non-forested vegetation such as farmland was in closer proximity to larger tracts of forest. These models can help wildlife and transportation managers to identify locations of high collision frequency for mitigation. Modifying certain landscape and roadside habitats can be an effective way to reduce deer-vehicle collisions.     

BIOLOGICAL INDICATORS AND BIOLOGICAL EFFECTS OF ESTUARINE/COASTAL POLLUTION1

ABSTRACT: Sustained interest in and concern about the health status of the aquatic environment has resulted in extensive research focused on (1) effects of pollution on survival, growth, and reproduction of resource species at all life stages; (2) diseases of fish and shellfish, as they may be related to pollution and as they may serve as indicators of environmental stress; and (3) contaminant body burdens in fish and shellfish - their effects on the aquatic animals and their potential effects on humans. Effects, lethal and sublethal, of pollutants on life history stages of fish and shellfish have been documented, as have impacts on local stocks in badly degraded habitats, but as yet there has been no adequate quantitative demonstration of effects on entire aquatic species - probably because of the difficulty in sorting out relative effects of the many environmental factors that influence abundance. Sublethal effects, especially those that result in disease, have been examined intensively, and some diseases and disease syndromes have been associated statistically with pollution. Other pollution indicators (biochemical, physiological, genetic, behavioral, and ecological) have also received some attention, as have body burdens of contaminants in aquatic species. Research, especially that conducted during the past decade, has done much to clarify the many pathways and toxic effects of contaminants on aquatic animals, and has also helped to identify mechanisms for survival of fish and shellfish in the presence of environmental changes caused by human activities.     

Journalists' views of advertiser pressures on agricultural news

All major journalism ethical codes explicitly state that journalists should protect editorial copy from undue influence by outside sources. However, much of the previous research on agricultural information has concentrated on what information various media communicate (gatekeeping studies) or communication's role in increasing innovation adoption (diffusion studies). Few studies have concentrated specifically on organizational and structural constraints that might adversely affect agricultural journalists' ethical standards; those that have, focus largely on farm magazines. A study of newspaper reporters who cover agricultural news found that the most pressing ethical concern is the effect of advertiser (agri-business) pressure on editorial copy, and that their concerns in general parallel those of farm magazine writers and editors. The majority reported being in situations in which they might be exposed to advertiser pressure, including pressures to change or withhold editorial copy. Large minorities suggested that advertising pressures affect the overall environment in which agricultural journalists work, and more than one in ten said they allow advertiser pressures to influence editorial decisions. The newspaper reporters who cover agricultural beats showed slightly more resistance to advertiser pressure than did farm magazine editors in a parallel study.     

Definition Procedures Have Little Effect on Performance of Environmental Classifications of Streams and Rivers

Mapped environmental classifications are defined using various procedures, but there has been little evaluation of the differences in their ability to discriminate variation in independent ecological characteristics. We tested the performance of environmental classifications of the streams and rivers of France that had been defined from the same environmental data using geographic regionalization and numerical classification of individual river valley segments. Test data comprised invertebrate assemblages, water chemistry, and hydrological indexes obtained from sites throughout France. Classification performance was measured by analysis of similarity (ANOSIM). Geometric regions defined by a regular grid and without regard to environmental variables and a posteriori classifications based on clustering the test datasets defined lower and upper bounds of performance for a given number of classes. Differences in classification performances were generally small. The ANOSIM statistics for the a posteriori classifications were around twice that of all environmental classifications, including geometrically defined regions. The hydro-ecoregions performed slightly better for the invertebrate data and the network classification performed slightly better for the chemistry and hydrological data. Our results indicate that environmental classifications that are defined using different procedures can be comparable in terms of their ability to discriminate variation of ecological characteristics and that alleged differences in performance arising from different classification procedures can be small relative to unexplained variation. We conclude that definition procedures might have little effect on the performance of large-scale environmental classifications and decisions over which procedures to use should be based primarily on pragmatic considerations.     

Provincial development plans in Zimbabwe: an analysis of their content,structure and methodology

Zimbabwean provincial plans were instituted to help in the achievement of the national goal of the creation of an egalitarian, socialist and integrated society. The national goal itself was adopted as an antithesis to the dualist society characterised by spatial, economic, social, politican and technological inequalities that Zimbabwe inherited from colonialism. This meant that provincial plans had to play both a functional (or growth allocating/distribution) and a territorial (or redistribution) role.

This paper reviews their role in achieving the national goal by examining their functions, content, structure and methodology. The paper concludes that because of their nature, provincial plans are not suitable tools for the achievement of the national goal.     

Surface applied water treatment residuals affect bioavailable phosphorus losses in Florida sands

Water treatment residuals (WTR) can reduce runoff P loss and surface co-application of P-sources and WTR is a practical way of land applying the residuals. In a rainfall simulation study, we evaluated the effects of surface co-applied P-sources and an Al-WTR on runoff and leacheate bioavailable P (BAP) losses from a Florida sand. Four P-sources, namely poultry manure, Boca Raton biosolids (high water-soluble P), Pompano biosolids (moderate water-soluble P), and triple super phosphate (TSP) were surface applied at 56 and 224kgPha(-1) (by weight) to represent low and high soil P loads typical of P- and N-based amendments rates. The treatments further received surface applied WTR at 0 or 10gWTRkg(-1) soil. BAP loss masses were greater in leachate (16.4-536mg) than in runoff (0.91-46mg), but were reduced in runoff and leachate by surface applied WTR. Masses of total BAP lost in the presence of surface applied WTR were less than approximately 75% of BAP losses in the absence of WTR. Total BAP losses from each of the organic sources applied at N-based rates were not greater than P loss from TSP applied at a P-based rate. The BAP loss at the N-based rate of moderate water-soluble P-source (Pompano biosolids) was not greater than BAP losses at the P-based rates of other organic sources tested. The hazards of excess P from applying organic P-sources at N-based rates are not greater than observed at P-based rates of mineral fertilizer. Results suggest that management of the environmental P hazards associated with N-based rates of organic materials in Florida sands is possible by either applying P-sources with WTR or using a moderate water-soluble P-source.     

Effect of Light on Biodegradation of Estrone, 17β‐Estradiol,and 17α‐Ethinylestradiol in Stream Sediment

Biodegradation of [A‐ring ¹⁴C] Estrone (E1), 17β‐estradiol (E2), and 17α‐ethinylestradiol (EE2) to ¹⁴CO₂ was investigated under light and dark conditions in microcosms containing epilithon or sediment collected from Boulder Creek, Colorado. Mineralization of the estrogen A‐ring was observed in all sediment treatments, but not epilithon treatments. No difference in net mineralization between light and dark treatments was observed for ¹⁴C‐E2. Net mineralization of ¹⁴C‐E1 and ¹⁴C‐EE2 was enhanced in light treatments. Extents of ¹⁴CO₂ accumulation and rates of mineralization were significantly greater for E2 than E1 under dark conditions, but were comparable under light conditions. These results indicate substantial differences in the uptake and metabolism of E1 and E2 in the environment and suggest biorecalcitrance of E1 relative to E2 in light‐limited environments. The extent of ¹⁴CO₂ accumulation and rate of mineralization for EE2 in dark treatments were less than half of that observed for E2 and generally lower than for E1, consistent with previous reports of EE2 biorecalcitrance. However, ¹⁴CO₂ accumulation and rates of mineralization were comparable for EE2, E2, and E1 under light conditions. These results indicate photoactivation and/or phototransformation/photodegradation processes can substantially enhance heterotrophic biodegradation of estrogens in sunlit environments and may play an important role in estrogen transport and attenuation.