Validation of a booted finite element model of the WIAMan ATD lower limb in component and whole-body vertical loading impacts with an assessment of the boot influence model on response

Objective: A novel anthropomorphic test device (ATD) representative of the 50th percentile male soldier is being developed to predict injuries to a vehicle occupant during an underbody blast (UBB). The main objective of this study was to develop and validate a finite element (FE) model of the ATD lower limb outfitted with a military combat boot and to insert the validated lower limb into a model of the full ATD and simulate vertical loading experiments.

Methods: A Belleville desert combat boot model was assigned contacts and material properties based on previous experiments. The boot model was fit to a previously developed model of the barefoot ATD. Validation was performed through 6 matched pair component tests conducted on the Vertically Accelerated Loads Transfer System (VALTS). The load transfer capabilities of the FE model were assessed along with the force-mitigating properties of the boot. The booted lower limb subassembly was then incorporated into a whole-body model of the ATD. Two whole-body VALTS experiments were simulated to evaluate lower limb performance in the whole body.

Results: The lower limb model accurately predicted axial loads measured at heel, tibia, and knee load cells during matched pair component tests. Forces in booted simulations were compared to unbooted simulations and an amount of mitigation similar to that of experiments was observed. In a whole-body loading environment, the model kinematics match those recorded in experiments. The shape and magnitude of experimental force–time curves were accurately predicted by the model. Correlation between the experiments and simulations was backed up by high objective rating scores for all experiments.

Conclusion: The booted lower limb model is accurate in its ability to articulate and transfer loads similar to the physical dummy in simulated underbody loading experiments. The performance of the model leads to the recommendation to use it appropriately as an alternative to costly ATD experiments.     

我国水环境有机物分析前处理技术

介绍了我国水环境有机物分析中常用的前处理技术,包括液液萃取、树脂吸附、固相萃取、固相微萃取、液膜萃取、半透膜被动采样、顶空、吹扫-捕集等,归纳了各种方法的原理、应用及优缺点,并对环境中有机污染物前处理技术的发展方向进行了展望。     

煤矿带式输送机事故分析及防护措施

带式输送机是煤矿生产中的一种主要运输设备,广泛应用在采区平巷、采区上下山、运输大巷及井口运输走廊等场所,是矿井煤炭运输系统的中枢,一旦发生故障,轻则耽误生产,重则造成人员伤亡.笔者以常见的煤矿带式输送机故障类型为例,分析其产生故障的根本原因,提出各种故障的预防措施;论述了煤矿带式输送机综合保护装置的基本功能和动作原理;通过带式输送机综合保护装置控制系统结构示意图,全面、客观地展示了煤矿用带式输送机容易发生各种故障的方位和自动保护装置测控元件的布局、电气控制原理,不仅可以适时监控带式输送机的工作状态,自动报警、显示、处理各种运行故障,还可以避免人为误操作带来的各种损失.     

工业废水中测定六价铬的预处理技术

根据复合絮凝剂与阳离子交换树脂两者在分离与处理技术上所起的不同作用 ,提出了将两法联合用作工业废水中测定Cr6 的预处理技术 ,通过一系列条件试验 ,确定最佳预处理条件。结果表明 ,该法具有去色、去浊率高 ,分离效果佳 ,排除干扰离子能力强 ,分析样品重现性好 ,准确度高 ,操作简便、快捷的优点。     

离心法应用于高浊度地表水中氨氮测定预处理过程中的方法

比较多种预处理方法去除浊度对地表水氨氮测定的影响,结果表明在测定高浊度地表水氨氮的过程中,采用离心法可较好地去除悬浮物对水样测定的干扰。较清水样用比色前离心方法,对于较浑浊的水样用絮凝沉淀结合比色前离心方法,可明显去除浊度的干扰,得到稳定的氨氮数值。2种方法的准确度和精密度均满足质控要求。     

我国健身器材质量和检验现状分析及其对策

笔者从产品质量、检测体系和质检监管等方面系统地阐述了我国健身器材产业的现状;通过对国内外健身器材产业的比较和分析,指出了我国健身器材产业普遍存在技术含量低,质量不稳定,检测标准和设备欠缺,服务不完善等突出问题;同时还具体探讨了国内外健身器材的安全要求和使用性能在生化和环保两方面的不足;就上述种种问题提出了相应的发展对策,即遵循\"以人为本,保障安全\"的原则,积极发展现代化生产企业,前瞻性地开发高技术含量的安全型产品,健全符合国情实际的检测体系,从而全面提升我国健身器材的安全性能、服务水平和市场竞争力.     

Biodiesel production from vegetable oil and waste animal fats in a pilot plant

In this study, corn oil as vegetable oil, chicken fat and fleshing oil as animal fats were used to produce methyl ester in a biodiesel pilot plant. The FFA level of the corn oil was below 1% while those of animal fats were too high to produce biodiesel via base catalyst. Therefore, it was needed to perform pretreatment reaction for the animal fats. For this aim, sulfuric acid was used as catalyst and methanol was used as alcohol in the pretreatment reactions. After reducing the FFA level of the animal fats to less than 1%, the transesterification reaction was completed with alkaline catalyst. Due to low FFA content of corn oil, it was directly subjected to transesterification. Potassium hydroxide was used as catalyst and methanol was used as alcohol for transesterification reactions. The fuel properties of methyl esters produced in the biodiesel pilot plant were characterized and compared to EN 14214 and ASTM D6751 biodiesel standards. According to the results, ester yield values of animal fat methyl esters were slightly lower than that of the corn oil methyl ester (COME). The production cost of COME was higher than those of animal fat methyl esters due to being high cost biodiesel feedstock. The fuel properties of produced methyl esters were close to each other. Especially, the sulfur content and cold flow properties of the COME were lower than those of animal fat methyl esters. The measured fuel properties of all produced methyl esters met ASTM D6751 (S500) biodiesel fuel standards.     

Ultrasound and enzyme assisted biodegradation of distillery wastewater

Irradiation with ultrasound (US) and use of an enzyme (E) as pretreatment techniques were carried out to treat a complex effluent (distillery wastewater). These two techniques have been used alone as well as in combination and the efficacy of these techniques was tested by subjecting the effluent to subsequent aerobic biological oxidation (AO). When used alone, US exposure for 30 min and 2 h yielded the best COD reduction during the aerobic oxidation step (US+AO). For the enzyme when used alone, a pH value of 4.8 (corresponding to the optimum pH of the enzyme), a dose of 50 U and a pretreatment time of 24 h yielded better COD removal efficiency as compared to untreated effluent (aerobic oxidation alone). When used in combination, ultrasound followed by enzymatic pretreatment (US+E+AO) yielded the best COD removal efficiencies during aerobic oxidation as compared to the other combinations tested for the treatment of the distillery wastewater. A 4-fold increase in the initial oxidation rate was observed over the untreated batch for the integrated technique (US+E+AO). On the basis of the variation in the values of the biokinetic parameters it can be concluded that the type of pretreatment scheme affects the subsequent rate of the aerobic oxidation significantly.     

基于小孔节流原理的高楼逃生缓降器设计与仿真

针对现有缓降器存在体积庞大、结构复杂、速度不可控等缺点,设计一款全新的可控速高楼逃生缓降器。首先,推导出缓降器的下降速度与节流小孔孔径之间的关系;然后,利用AMESim软件建立缓降器的动力学模型,仿真模拟不同负载、不同节流孔径下缓降器的下降速度;最后,仿真分析确定节流小孔通径安全调节范围,并通过调节串联在2液压缸之间的节流小孔孔径大小,达到变速缓降的目的。结果表明:该缓降器结构简单、体积小巧,使用者可根据逃生需求在节流孔径1~6 mm 内任意调节缓降器的下降速度,且速度不超过1.5 m/s。针对不同体重的使用对象,该缓降器的速度变化幅度始终趋于稳定,极大地提升了缓降器的适用性和安全性。