汽车零部件金属卤素灯阳光模拟试验与户外自然曝晒的相关性研究

目的 探究汽车零部件金属卤素灯阳光模拟加速试验与户外自然曝晒的关系。方法 使用3种典型高分子透明材料分别进行阳光模拟加速试验、AIMBOX/Arizona户外曝晒和Florida户外曝晒,基于试验后样品的黄变值,比较阳光模拟试验与户外曝晒的相关性,并对阳光模拟试验与户外曝晒的加速性进行探讨。结果 阳光模拟（IP/DP箱）加速试验与AIM BOX/Arizona户外曝晒高度相关,综合加速倍率约是AIM BOX/Arizona户外曝晒的3倍。阳光模拟（IP/DP箱外）加速试验与Florida户外曝晒高度相关,综合加速倍率是Florida户外曝晒的7倍。结论 基于3种典型材料研究可知,汽车零部件阳光模拟加速试验与典型户外自然曝晒具有一定相关性。     

某海域极端环境下15万吨级FPSO波浪荷载数值研究

目的 评估在役15万吨级FPSO在某海域百年一遇极端波浪作用下典型横剖面的水动力特性,进而得到FPSO的极值荷载,作为FPSO返坞改造的关键控制参数。方法 基于国产自主三维频域线性势流软件COMPASS-WALCS,建立15万吨级FPSO湿表面网格模型,根据三维绕射-辐射理论,计算湿表面上的水动力荷载,将每个绕射单元上的水动压力直接映射到结构模型上进行计算。采用谱分析方法对百年一遇海况进行分析,得到短期运动极值响应。对响应幅值算子(RAO)和波能谱密度进行谱分析,得到极端波浪下的响应谱,进而得到浮体运动和波浪荷载短期预报各种统计值,利用统计方法求得短期响应的最大值。结果 计算了船中部Fr143横剖面的载荷极值,即垂向弯矩、垂向剪力、剖面型心加速度等,发现船舶迎浪时弯矩值最大,随着浪向角增大,弯矩值逐渐减小,剖面垂向剪力则随着浪向角增大逐渐增大。结论 FPSO在极端波浪作用下,其大迎浪角条件下荷载更加危险,需要给予格外关注。     

粘土防渗尾矿库地震永久位移数值模拟

我国目前的防渗尾矿库数量越来越多,但对其动力分析相对较少。结合工程实际,使用FLAC2D软件建立了有限差分数值模型,对采用粘土垫层防渗的尾矿库进行二维地震动力响应分析,并将计算得到的坝顶最大水平位移与传统简化方法的计算结果进行了对比分析。计算结果表明,由于数值分析考虑了尾矿坝对地震波的放大效应,通过有限差分数值模型计算的水平位移比简化方法的计算结果大60%。参数分析表明:防渗垫层的抗剪强度对于尾矿库动力响应影响较大,其虽有一定隔震作用,使得防渗层上部的最大水平加速度低于其下部的最大水平加速度约5%~30%,但随着防渗垫层抗剪强度的降低,尾矿库的失稳模式由经过尾矿内部的圆弧形滑动向经过防渗层的楔形滑动转变,尾矿库的屈服加速度显著降低,永久水平位移从小于5cm增加到近70cm,可能造成震陷等灾害。该分析方法和结果对于地震区防渗尾矿库工程的设计有一定的参考价值。     

对医用加速器产生感生放射性的分析与探讨

通过对某医用加速器处于不同能量的电子束或X射线所产生的感生放射性在关机后的不同时刻,进行γ辐射剂量率和中子剂量当量率的测量,分析其随时间的变化趋势及对医务人员所造成的影响,并提出了有针对性的建议.     

Load Acceleration and Footstep Strategies in Asymmetrical Lifting and Lowering

Accelerated execution effects for lifting and lowering a 12-kg box using two footstep strategies associated with experienced workers were studied. Eight healthy male participants performed a normal and an accelerated execution of a lifting task and a lowering task, using a minimal feet displacement strategy (oblique-step) and a strategy with a step (crossed-step). It was hypothesized that the accelerated executions, as compared to the normal executions, would have a different effect on L5/S1 resultant moment, body posture, and other kinematic variables. A tridimensional dynamic rigid body model was used to compute L5/S1 resultant moments. Results showed that the accelerated condition did not reduce body asymmetry of posture, but it reduced the length of the path of the global center of gravity and the duration of the supporting phase of the box, and it did not significantly affect L5/S1 maximal resultant moments for lifting but increased them for lowering. These results indicate that the net work production for accelerated strategies might be smaller, which may represent an economy of energy. Furthermore, the results showed that the use of an accelerated strategy for lowering should be avoided.     

爆炸形成过程中火焰加速的试验研究

为预防和控制工业爆炸事故,并为脉冲爆轰发动机的研究提供理论指导,分析火焰加速导致的燃烧转爆轰过程的影响因素。采用爆轰管探讨障碍物的阻塞比、混合物的组成、初始压力和点火能等4个因素对爆炸性气体火焰速度和爆轰压力的影响规律。试验结果表明:障碍物的存在能大大提高火焰速度和爆轰压力;爆轰压力随管内障碍物阻塞比的增大先变大后减小,并在阻塞比为0.498,燃料种类为天然气,化学当量比为1时达到最大;爆轰压力还随混合气体初始压力的增大和点火能的提高而增大。选择适宜的条件可大大提高火焰加速速率,促进燃烧向爆轰过程转变。     

加速溶剂萃取-固相萃取净化-高效液相色谱法测定玉米作物中多环芳烃含量

建立了加速溶剂萃取-固相萃取净化-高效液相色谱测定玉米作物中15种多环芳烃的方法,优化了试验条件.方法线性关系良好,15种多环芳烃的检出限在0.003 8～0.079μg/kg之间,空白加标试验的相对标准偏差在3.9%～11.7%之间,基质加标回收率在69.3%～115.3%之间.实际样品的测定结果表明,该方法分离效果...     

航空电连接器海洋环境加速试验与腐蚀仿真研究

目的 通过加速试验和有限元仿真,研究航空电连接器在南海岛礁服役条件下的失效行为和腐蚀机理.方法 根据典型航空装备南海服役环境数据,设计海洋环境加速腐蚀试验环境谱,基于此环境谱开展航空电连接器在实验室加速试验条件下的外观腐蚀、接触电阻、绝缘电阻和耐压强度的变化行为和机理研究.重点分析接触电阻变化原因,并基于水平集方法,建立插针插孔结合处的COMSOL有限元腐蚀仿真模型,模拟和验证接触件的腐蚀行为和机理.结果 3种规格的电连接器均发生壳体腐蚀,但程度不同,其中不锈钢壳体电连接器壳体腐蚀最轻,但壳体内部金属卡圈腐蚀最严重,其接触电阻波动最大.所有电连接器的耐压强度和绝缘电阻均有明显减小.结论 导致接触电阻增加的直接原因是插针和插孔结合处的毛细区内发生了严重腐蚀.有限元模型复现了腐蚀界面发展和腐蚀产物沉积过程.     

Evaluation of limits for effective flame acceleration in hydrogen mixtures

Results of experiments and data analysis on turbulent flame propagation in obstructed channels are presented. The data cover a wide range of mixtures: H₂/air, H₂/air/steam (from lean to rich) at normal and elevated initial temperatures (from 298 to 650 K) and pressures (from 1 to 3 bar); and stoichiometric H₂/O₂ mixtures diluted with N₂, Ar, He and CO₂ at normal initial conditions. The dataset chosen also covers a wide range of scales exceeding two orders of magnitude. It is shown that basic flame parameters, such as mixture expansion ratio σ, Zeldovich number β and Lewis number Le, can be used to estimate a priori a potential for effective flame acceleration for a given mixture. Critical conditions for effective flame acceleration are suggested in the form of correlations of critical expansion ratio σ^* versus dimensionless effective activation energy. On this basis, limits for effective flame acceleration for hydrogen combustibles can be estimated. Uncertainties in determination of critical σ^* values are discussed.     

Coping with accelerating socio-technical systems

In 1997 a workshop was held on the subject of how to cope with accelerating technologies. These are industries such as aviation, air traffic control and biotechnology, amongst others, where the rate of technological development is significant. A number of papers were presented from a range of viewpoints and in a variety of different industrial contexts. The papers ranged from theoretical models to help understand the process of acceleration and its impact on organisational learning, to practical analyses of future potential risks in specific accelerating industries such as air traffic control. The aim of the papers and the workshop as a whole was to provide insight into the problems associated with accelerating technologies, and thereby derive measures to control or cope with such acceleration. The problems arising from acceleration, as predicted by the theoretical models and evidenced by experiences in accelerating industries (e.g. aviation) are manifold. Two examples of particular problems are unforeseen risks in an industry (a lack of forward vision), and a failure to learn adequately (i.e. in time) from incidents occurring in an organisation (a lack of constructive hindsight). There is also an incipient danger of society being driven by technology rather than being led by social needs. Even if each technology ultimately becomes ‘ultra-safe’, it will nevertheless have its own ‘event horizon’, limiting useful further progress. Each of the papers from the workshop is summarised and integrated into a three-part synopsis of the workshop. This covers the context of accelerating technologies, modelling their impacts, and deriving coping strategies. Four of the papers are included in their entirety as separate papers in their own right in this special issue of Safety Science.