对经典冲击和冲击响应谱的探讨

产品在生产、运输及使用过程中常面临各种冲击环境,容易引起产品质量和可靠性方面的诸多问题,因此在产品研制生产过程中需要进行冲击试验,本文对经典冲击和冲击响应谱试验进行原理分析,认为产品实际冲击环境非常复杂,应根据产品冲击环境的实测值和试验目的进行试验方法选择。最后根据两种试验方法的实际应用和相关标准的修订情况,提出了冲击响应谱在验证产品设计参数或可靠性等方面的优势,成为冲击试验的发展趋势。     

不同冲击波形的等效方法

产品在运输、使用和维修过程中可能遭受的冲击环境条件很复杂,影响冲击的因素颇多.本文重点探讨波形对冲击效果的影响以及三种标准波形之间的等效问题.     

冲击响应谱与经典冲击试验等效计算方法

产品即使在试验室里通过了经典冲击试验环境,在实际使用环境中还有损坏。因此简单采用经典冲击作为检测条件的试验规范已经不能满足使用需求。另外,试验中,给定的波形量级与脉宽往往超出电动振动台或冲击台的性能范围,阻碍了试验的顺利进行。基于等效冲击试验原理,采用冲击响应谱(SRS)代替经典冲击。运用改进的递归数字滤波法编制经典脉冲的冲击响应谱计算程序,实现了经典冲击与冲击响应谱的等效计算。算例和试验表明,方法合理可行。     

军用设备淋雨环境试验技术

淋雨试验方法是一种人工环境试验方法.这里简要介绍了进行淋雨环境试验的目的、适用范围及环境影响因素,并说明应从产品使用环境、本身特点及产品技术条件的角度出发来考虑确定各试验参数,同时指出应根据产品结构状态、使用目的来选择试验程序.     

测定产品脆值试验的优化方案

文章介绍了使用冲击试验机测定产品脆值试验方法的优化方案。在传统冲击试验机测定产品脆值的试验方法的基础上,通过分析产品的内部结构与特征,在样品上进行加速度传感器的布置,使用样品内置传感器的反馈数据测定产品脆值以及损坏边界,为产品研发以及相应的包材设计提供更详细的数据支持。     

基于模态分析的某航天产品结构改进设计研究

本文提出基于模态分析的产品结构改进设计流程,并采用该流程对某航天产品进行改进设计。该产品改进前结构基频仿真结果为53Hz,产品在正弦振动条件下部分单机响应有较大倍数放大,不能满足要求;改进后结构基频的仿真结果达到115Hz,同比增加117%,可以满足要求。案例表明本文方法的合理有效性,达到了节省研制周期与成本的目的。     

温度冲击试验标准的介绍和分析

本文从试验目的和应用对象对试验设备要求和试验条件等方面对GJB 150、GB 2423、810F三个系列标准的温度冲击试验进行了介绍和分析,指出了其共同点和不同点,重点说明温度冲击与温度变化试验概念上的区别,简单介绍了810F中的基于高温循环的温度冲击试验程序的应用和该程序中高温循环部分的实施方法.     

某机载雷达舱外设备振动冲击试验夹具设计

为了合理地设计符合振动冲击环境试验要求的夹具,根据某机载雷达舱外设备振动冲击试验条件及有关振动环境试验夹具设计规范,对该雷达舱外设备振动冲击试验夹具进行了结构动力特性设计。振动冲击试验表明:夹具的动态特性满足了振动冲击环境试验夹具设计的要求。某机载雷达舱外设备振动试验时,加速度谱密度值的控制误差明显小于±3dB,完全符合有关振动环境试验规范的要求,冲击试验控制精度也满足试验标准要求。因此,该夹具设计是成功的。     

随机振动试验控制原理

一.控制随机振动的必要性 许多产品在使用时,或者在运输过程及生产过程中都承受振动。因此很有必要确定产品是否经受得住振动及是否工作可靠。当然,有时还需确定产品在实用环境中的寿命。 很自然,在设计既要求精度高、重量轻、成本低,又要求在苛刻条件下使用的高级技术产品时,这些问题显得非常重要。例如,在航天工业中,一般产品结构都极其复杂,造价都很高,在进行产品试验时很值得考虑其可靠性和安全性。 另一方面,为了保证产品的包装能有效地经受住运输过程的冲击和振动,也需要进行振动试验。     

冲击响应谱规范试验室模拟述评

冲击响应谱试验已是航天产品必做的力学环境试验,本文介绍了目前试验室普遍使用的冲击响应谱模拟的手段,阐述了用电动振动台模拟和用机械式试验机模拟的差异,并对存在的差异进行了讨论。     

环境适应性试验项目的选择

介绍低气压试验、高低温试验、湿热试验、IP防护等级试验、振动试验、冲击和碰撞试验、盐雾试验等试验项目的考核目的和相应试验参数，分析上述试验项目的适用范围。并根据当前产品的发展状况，简单介绍环境试验项目的组合和试验顺序。     

Comparison of different pre-treatment methods for enriching hydrogen-producing bacteria from intertidal sludge

Batch tests of cultivations were conducted to analyze influences of pre-treatment methods (heat–shock, acid, and alkaline) on hydrogen production. The hydrogen yields of the pre-treated samples were significantly higher than those without pre-treatment. Heat–shock pre-treatment yielded maximum hydrogen (75.5 ± 4.0 mL/g sucrose_removed), and had the highest sucrose removal efficiency (81.20 ± 1.23%). Heat–shock pre-treatment produced more ethanol and acetate (80.44 ± 0.55% of the total soluble metabolites), which belonged to ethanol-type fermentation. Denaturing gradient gel electrophoresis (DGGE) profiles showed that pre-treatment methods affected the composition of microbial communities. The results showed that pre-treatment methods play a key role in the hydrogen production process of marine hydrogen-producing microflora.     

基于仿真分析的复杂电子装备测试性预计技术研究

测试性是产品的一种设计特性,是伴随功能原理设计时赋予产品的一种固有属性。随着电子产品及设备的复杂和多样化,导致其故障诊断越来越困难,产品的测试性也逐渐得到生产和使用单位的重视。为尽早在研制阶段对产品的测试性水平进行评估,发现测试性设计的薄弱环节,首先对测试性仿真技术进行了简单介绍,之后详细阐述了基于TEAMS的测试性仿真方法,最后以某型柴油机系统为例,对其测试性指标进行预计,同时发现产品测试性设计上的薄弱环节,为产品的设计改进提供建议。     

Economic assessment of the health effects related to particulate matter pollution in 111 Chinese cities by using economic burden of disease analysis

With China's rapid economic development, environmental problems have become more and more serious. Particulate air pollution is terrible in cities with large and dense population. It may lead to adverse health effects and economic costs. In this study, we calculated the health effects of pollution caused by particulate matter with aerodynamic diameters less than 10mum (PM(10)) in 111 Chinese cities in 2004 according to statistical data and epidemiological exposure-response functions. Using economic burden of disease analysis, an economic assessment of these health risks was also presented. In contrast to many previous studies that have examined individual cities, this study covered most large and medium-sized cities in China, which accounted for more than 70% gross domestic product (GDP) of China in 2004. The total economic cost caused by PM(10) pollution was estimated as approximately US$ 29,178.7 million. Mega cities such as Beijing, Shanghai, and Tianjin contribute relatively more to the total costs. The results will help policy makers in formulating more effective countermeasures and increasing public awareness to enhance environmental protection.     

“My Husband Usually Makes Those Decisions”: Gender,Behavior, and Attitudes Toward the Marine Environment

Human behavior impacts the environment we live in. In order to better understand how one group, boat owners, in three Nordic countries adjacent to the Baltic Sea; Sweden, Finland and Denmark, viewed the relationship between the marine environment, leisure boats and issues of responsibility, a survey study was conducted (n = 1701). The results show that there are differences between gender in many areas and those women in general are more environmentally friendly than men in their views and behavior. Men and women seek information about boating by different channels and this knowledge may be used in future information campaigns. Both men and women ranked boat owners as having the lowest impact on the marine environment and perceived these to be responsible for addressing environmental issues caused by leisure boat activities. The results also show that it is important to prove the effectiveness of an environmentally safe product since this factor is ranked higher than price when considering buying a product. The results suggest that once environmentally friendly behavior is established, such as recycling, this behavior continues. One implication of this study is that small changes in human behavior are seen as acceptable but larger commitments are more difficult to achieve. If individuals do not feel responsible for causing environmental damage, this aspect needs to be addressed in information aimed at this group. Novel approaches on framing the information and new ways of disseminating information are needed.     

Allocation solutions for secondary material production and end of life recovery: Proposals for product policy initiatives

This paper aims at analysing how secondary materials production and end of life recovery processes are modelled in life cycle-based environmental assessment methods in order to discuss their suitability in product policy-support contexts, with a focus on Sustainable Consumption and Production (SCP) policies. The equations prescribed in three published, widely recognised standards are evaluated. In addition, more recent modelling approaches that have been adopted in the context of two EU product policy initiatives (the Product Environmental Footprint (PEF) and the Resource Efficiency Assessment of Products (REAPro)) are similarly analysed. All of the methods are scrutinised against eight criteria which we deem to be important in product policy-support contexts, including comprehensiveness, accommodation of open-loop and closed-loop product systems, and consideration of recyclability/recoverability rates, to name a few. Based on this analysis, it is suggested that the PEF and REAPro modelling approaches appear to be better suited for use in product policy-support contexts than do the currently widely endorsed methods that we considered.     

Characterizing the Relative Contributions of Large Vessels to Total Ocean Noise Fields: A Case Study Using the Gerry E. Studds Stellwagen Bank National Marine Sanctuary

In 2006, we used the U.S. Coast Guard’s Automatic Identification System (AIS) to describe patterns of large commercial ship traffic within a U.S. National Marine Sanctuary located off the coast of Massachusetts. We found that 541 large commercial vessels transited the greater sanctuary 3413 times during the year. Cargo ships, tankers, and tug/tows constituted 78% of the vessels and 82% of the total transits. Cargo ships, tankers, and cruise ships predominantly used the designated Boston Traffic Separation Scheme, while tug/tow traffic was concentrated in the western and northern portions of the sanctuary. We combined AIS data with low-frequency acoustic data from an array of nine autonomous recording units analyzed for 2 months in 2006. Analysis of received sound levels (10–1000 Hz, root-mean-square pressure re 1 μPa ± SE) averaged 119.5 ± 0.3 dB at high-traffic locations. High-traffic locations experienced double the acoustic power of less trafficked locations for the majority of the time period analyzed. Average source level estimates (71–141 Hz, root-mean-square pressure re 1 μPa ± SE) for individual vessels ranged from 158 ± 2 dB (research vessel) to 186 ± 2 dB (oil tanker). Tankers were estimated to contribute 2 times more acoustic power to the region than cargo ships, and more than 100 times more than research vessels. Our results indicate that noise produced by large commercial vessels was at levels and within frequencies that warrant concern among managers regarding the ability of endangered whales to maintain acoustic contact within greater sanctuary waters. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Influence of a 1,800 MHz electromagnetic field on the EEG energy

The present study investigated the influence of electromagnetic fields (EMF), similar to that emitted by mobile phones, on brain activity. Ten women and ten men, matched for age and educational level, performed a short memory task (Wechsler test), with simultaneous Electroencephalogram (EEG) recordings at 15 scalp electrodes, both without (baseline) and with exposure to an 1,800 MHz signal. The EEG energy was found concentrated at the four basic EEG bands [α (8–13 Hz), β (14–30 Hz), δ (0–4 Hz), and θ (5–7 Hz)]. The analysis revealed that in the presence of EMF, the energy of the β band was significantly greater for females than for males at the majority of the electrodes. Since beta oscillation is associated with the shift of attention during the perception, these findings may indicate that the particular EMF (1,800 MHz signal) exerts an influence on this brain activity, which appears to be gender-related.     

Does an energy efficiency label alter consumers' purchasing decisions? A latent class approach based on a stated choice experiment in Shanghai

In this paper we conducted a hypothetical choice experiment in Shanghai, China, to examine whether the China Energy Efficiency Label influences consumers' choices of air conditioners and refrigerators. A latent class approach was applied to observe both heterogeneities among the respondents and product brands. Our results suggested that consumers in Shanghai were well aware of the China Energy Efficiency Label and tended to pay more attention to products with such labels. In addition, air conditioners and refrigerators affixed with a hypothetical label that indicates saving in electricity bills compared with a standard model received significant preferences, which suggested that the more information manufacturers provide, the more their products would be preferred by consumers. Finally, weighted by class probability, the willingness to pay values for more energy efficient refrigerators were higher than those for more energy efficient air conditioners, implying that Shanghai consumers have greater incentive to pay more for appliances they use more frequently.