生态环境材料——社会可持续发展的物质基础

 生态环境材料是近年来在先进材料研究中提出的一个新研究领域。简要介绍了生态环境材料概念的产生、发展及哲学基础,从材料环境协调性评价、材料和物质的再生循环、与生态系统相协调的材料与工程、环境工程材料、与材料科学相关的生态工程等几方面对生态环境材料研究的最新进展进行了评述。     

用胞映射法分析双线性结构刚度的机翼颤振

将映射轨迹追踪技术引入基于空间Poincar啨截面的胞映射方法中 ,并定义初值分析空间 ,以适应分析高维动力系统运动类型初值域的需要。改进后胞空间中胞的数目大大减少 ,计算时间缩短 ,运动特征的确认更为准确。应用该方法研究扭转方向具有双线性结构刚度因素的机翼颤振问题 ,结果显示 ,初始条件对系统动力学行为有着很大的影响。当两段刚度之比小于某临界值时 ,随着机翼颤振速度增大 ,不同的初始条件会导致平衡点、极限环振动、复杂的周期运动、混沌和发散运动等不同的运动形式     

变循环发动机过渡态性能直接模拟方法

为了实现多变量可调的变循环发动机（VCE）过渡态性能模拟和控制规律设计,在稳态逆算法和过渡态性能隐式格式计算方法的基础上开发了变循环发动机过渡态直接模拟方法。在稳态逆算法模型中加入容积效应和转子动力学方程,实现了同时给定加速率、涡轮前温度和压缩部件工作点的条件下直接模拟计算过渡态过程中变几何参数和燃油流量的调节规律,验证了方法的精度和可行性,并将该方法用于变循环发动机转模态性能模拟和控制规律设计。计算结果表明,过渡态直接模拟方法的误差在0.58%以内,超声速巡航状态下由单外涵模态转换到双外涵模态的时间约为1 s,海平面静止状态下双外涵转单外涵的时间约为3 s,且推力、转速、涡轮前温度、喘振裕度等参数过渡平稳。该方法可简化转模态控制规律设计流程,并提高设计精度。     

基于滑模自适应控制的不确定混沌系统修正函数投影同步

研究了一类不确定混沌系统的修正函数投影同步。首先,设计了一类滑模曲面;基于该曲面设计了同步控制器,并采用自适应技术设计了自适应律对不确定参数进行逼近。在一定条件下,该同步控制方案可以实现2个不确定异结构混沌系统的修正函数投影同步。然后,为保证合适的控制量,对控制增益进行了优化。从同步效果来看,所设计的控制器对混沌系统的不确定项的影响具有较强的鲁棒性。最后,数值仿真验证了该控制器的有效性和可行性。     

Earth observation from space – The issue of environmental sustainability

Remote sensing scientists work under assumptions that should not be taken for granted and should, therefore, be challenged. These assumptions include the following:1. Space, especially Low Earth Orbit (LEO), will always be available to governmental and commercial space entities that launch Earth remote sensing missions.2. Space launches are benign with respect to environmental impacts.3. Minimization of Type 1 error, which provides increased confidence in the experimental outcome, is the best way to assess the significance of environmental change.4. Large-area remote sensing investigations, i.e. national, continental, global studies, are best done from space.5. National space missions should trump international, cooperative space missions to ensure national control and distribution of the data products.At best, all of these points are arguable, and in some cases, they're wrong. Development of observational space systems that are compatible with sustainability principles should be a primary concern when Earth remote sensing space systems are envisioned, designed, and launched. The discussion is based on the hypothesis that reducing the environmental impacts of the data acquisition step, which is at the very beginning of the information stream leading to decision and action, will enhance coherence in the information stream and strengthen the capacity of measurement processes to meet their stated functional goal, i.e. sustainable management of Earth resources. We suggest that unconventional points of view should be adopted and when appropriate, remedial measures considered that could help to reduce the environmental footprint of space remote sensing and of Earth observation and monitoring systems in general. This article discusses these five assumptions in the context of sustainable management of Earth's resources. Taking each assumption in turn, we find the following:(1) Space debris may limit access to Low Earth Orbit over the next decades.(2) Relatively speaking, given that they're rare event, space launches may be benign, but study is merited on upper stratospheric and exospheric layers given the chemical activity associated with rocket combustion by-products.(3) Minimization of Type II error should be considered in situations where minimization of Type I error greatly hampers or precludes our ability to correct the environmental condition being studied.(4) In certain situations, airborne collects may be less expensive and more environmentally benign, and comparative studies should be done to determine which path is wisest.(5) International cooperation and data sharing will reduce instrument and launch costs and mission redundancy. Given fiscal concerns of most of the major space agencies – e.g. NASA, ESA, CNES – it seems prudent to combine resources.     

Solar cycle variation of “killer” electrons at geosynchronous orbit and electron flux correlation with the solar wind parameters and ULF waves intensity

To construct models for hazard prediction from radiation belt particles to satellite electronics, one should know temporal behavior of the particle fluxes. We analyzed 11-year variation in relativistic electron flux (E>2 MeV) at geosynchronous orbit using measurements made by GOES satellites during the 23rd sunspot cycle. As it is believed that electron flux enhancements are connected with the high-speed solar wind streams and ULF or/and VLF activity in the magnetosphere, we studied also solar cycle changes in rank order cross-correlation of the outer radiation belt electron flux with the solar wind speed and both interplanetary and on-ground wave intensity. Data from magnetometers and plasma sensors onboard the spacecraft ACE and WIND, as well as magnetic measurements at two mid-latitude diametrically opposite INTERMAGNET observatories were used. Results obtained show that average value of relativistic electron flux at the decay and minimum phases of solar activity is one order higher than the flux during maximum sunspot activity. Of all solar wind parameters, only solar wind speed variation has significant correlation with changes in relativistic electron flux, taking the lead over the latter by 2 days. Variations in ULF amplitude advance changes in electron flux by 3 days. Results of the above study may be of interest for model makers developing forecast algorithms.     

涡轮基组合循环发动机分布式控制系统通信网络混合拓扑结构优化方法

涡轮机组合循环(Turbine based combined cycle,TBCC)发动机控制系统通信网络拓扑结构是其分布式控制系统方案设计的重要部分,优化网络拓扑结构可提高发动机推重比和控制系统可靠性。本文基于智能优化算法提出TBCC分布式控制系统网络拓扑结构优化方法。基于图论建立TBCC几何模型和网格模型,以重量和可靠性为优化性能指标,同时考虑发动机表面高温区域以及控制节点的工作可靠性,分别采用粒子群算法和遗传算法优化星形结构中智能中央节点位置、中央节点的环形拓扑结构,获得星形-环形混合拓扑结构。仿真实例表明,基于本文方法优化所得的混合拓扑结构相较于星形集中式控制结构,系统重量降低了51.9%。     

依托ERP实现固定资产全寿命周期管理

固定资产是企业的重要劳动资料,是实现资产保值增值的重要工具。现有的固定资产管理模式已经无法应对当前电网企业对固定资产管理新形势的要求。资产全寿命周期管理是以资产的整体目标出发,统筹考虑资产的整个生命周期,在满足安全、效能的前提下追求资产全寿命周期成本最优的管理模式。本文提出通过运用ERP系统在固定资产生命周期内构建出一套完整的固定资产管理新模式,并通过在某地市级供电公司的实际运用,得出了运用此种新模式可以实现固定资产使用效率提高、全寿命周期成本降低的管理新要求。     

改进剥层应变法测量铝合金预拉伸厚板内部残余应力分布

铝合金预拉伸板已广泛应用于航空整体结构件的制造,其内部初始残余应力引起的加工变形已严重制约新型飞机的研制和生产。测量残余应力的方法很多,但一般只能测量工件的表面和浅表层,而厚板内部残余应力测量一直是工程中的难点。文中针对铝合金预拉伸厚板的特点,提出了测量其内部残余应力的方法,并运用弹性力学理论进行了理论推导,得到了应力-应变关系矩阵。用该方法测量了7050T7451铝合金厚板内部残余应力,并对测试结果进了分析和比较。结果表明,本文提出的方法有效地解决了厚板内部残余应力测量的难题,有较高的工程应用价值。     

基于GIS面向LCA的产品材料信息管理系统建构

为解决传统生命周期评价(Life cycle assessment,LCA)空间位置数据缺失的问题,论文通过引入地理信息系统(Geographic information system,GIS)系统实现了空间位置数据的获取。论述了将空间位置数据引入LCA的必要性与可能性,提出了全新的产品材料管理信息系统功能结构与数据库框架。提出了空间位置数据的获取和有效管理的新方法,对产品材料数据库的进一步完善,以及LCA方法的进一步改进,具有非常重要的意义。