机械系统的风险概率与经济性安全评价方法研究与应用

针对机械事故频发,为预防和控制事故,依据安全评价发展方向,结合安全系统工程、模糊可靠性理论、人因可靠性技术和安全经济学,从人-机-环3方面分析风险评价因素,建立符合客观实际的风险评价模型,提出包括人为因素、机械设备和环境在内的基本事件失效概率估算方法;以安全经济学的角度将事故严重度量化为风险经济损失,根据每个风险因素的风险概率和风险经济损失来选择风险评价项目,通过检查评价项目状况,最终得出系统风险度,从而形成关于机械系统的定量风险概率与经济性安全评价方法。并给出起重机大车运行机构的工程示例,验证该方法的正确性和可行性。     

于桥水库周边农业小流域氮素流失浓度特征

选择天津市水源地于桥水库周边2个典型的农业小流域进行了长期的氮素流失研究.结果表明,地表径流的总氮浓度以村庄和果园为最高,平均浓度在20 mg·L-1左右;农田次之,山坡最低,平均浓度低于10 mg·L-1.亚表层流中氮素流失在不同地点和不同降雨事件中浓度有较大差异,总体趋势以果园最高,村庄中菜园次之,农田最低.在流域出口处.曹各庄流域地表径流总氮浓度达到18.5 m8·L-1,桃花寺流域出口处浓度为5.9 mg·L-1,流域内不同景观格局和迁移廊道地貌的差异是造成2个流域氮素流失浓度差异的主要原因.曹各庄流域中主要污染源村庄离水库较近(约200 m),且道路型季节性河流等性质特征对污染物的滞留能力较弱,增加了氮素流失到受纳水体的风险;桃花寺流域的污染源村庄和果园离受纳水体较远(约1500 m),氮素在季节性河流迁移过程中被小石坝、植被过滤带和干塘等"汇"型结构所滞留.从而降低了向水体迁移的风险.     

脉冲法对隔声屏障顶端式样的衍射分析

介绍了声屏障顶部结构衍射的评价标准和计算方法。给出了具有T型、橄榄型、弧型、L型等4种不同顶端式样声屏障的衍射声场有限元分析,以及使用脉冲方法得到的各种顶端式样在隔声屏障铺设吸声材料和不铺设吸声材料两种情况下插入损失的计算结果。     

秸秆和肥料管理措施对太湖流域水稻种植氮流失的影响

稻田系统的氮流失是农业面源污染的重要组成部分. 当前,氮肥投入量已得到有效控制,针对不同秸秆和肥料管理措施的多途径（径流、侧渗、下渗）氮流失特征研究还较为缺乏. 对此,选取太湖流域种植时长超过20 a且持续秸秆还田超过5 a的稻田,研究秸秆和肥料管理措施对水稻全生育期不同途径氮流失的影响,并基于作物产量、氮利用效率及氮流失强度,对秸秆和肥料管理措施的生产适宜性和环境友好性进行研判. 结果表明,秸秆离田会提升水稻植株对施氮的敏感度. 稻季氮总流失量为9~17 kg·hm^-2,占氮肥施用量的5%~7%. 对秸秆管理而言,秸秆离田的泡田排水具有更高氮流失风险;秸秆还田可降低15%以上的下渗途径氮流失量,但是对侧渗途径的氮流失作用并不明确. 对肥料管理而言,有机肥的适宜替代可较同施氮梯度下的化肥施用减少16%的种植期径流氮流失、26%的下渗氮流失,以及37%的侧渗氮流失. 综合产量数据,实施秸秆还田和肥料类型优化能够有效降低生产单位重量稻米的氮流失量,切实实现对农业生产和环境友好的双向兼顾.     

ZR-KVV电缆排布数量对燃烧特性影响的实验研究

电缆在实际布置情况下通常是多根成束装配,而电缆的排布数量对运行安全性有很大影响,研究电缆的排布数量对燃烧特性的影响具有重要意义。使用锥形量热仪,对ZR-KVV电缆以不同数量排布,研究分析其质量损失速率、热释放速率等主要燃烧性能参数。实验结果表明,当电缆受到固定火源的辐射热流影响时,质量损失速率峰值和热释放速率峰值随着水平布置电缆数量的增加呈指数递增;随着外部辐射热流强度的增强,质量损失速率峰值和热释放速率峰值增加,总热释放速率则减小。     

国内外机载电子设备液体冷却系统分析

首先分析了国内外机载电子设备液冷系统的工作原理,即冷却液在液体泵的作用下,进入电子设备冷板,带走电子设备的热量,再通过热交换器进行降温处理,热量传递到空气或燃油中,降温后的冷却液流向液体泵,进行下一次的冷却循环。其次分析了某些机载电子设备因安装位置不适用液冷系统,则采用强迫通风为其进行冷却,但热量最终经过空气还是传递至液冷系统中。最后对未来飞机的液体冷却技术进行了展望,液冷系统未来的发展趋势一定是有区域故障隔离能力,且冷却液的流量是随着热载荷而动态变化的,其代偿损失也较小。     

碳纤维混凝土的耐火性能试验测试与分析*

为研究不同碳纤维体积掺量（0,0.2%,0.6%,1%,1.5%,2%）对混凝土耐火性能的影响,考察不同温度环境下（20,60,100,300,500,800 ℃）的混凝土质量损失率与抗压强度损失率的变化情况;分析高温环境下混凝土的静置时间（0,1,3,7,12 h）对混凝土抗压强度损失率的影响。结果表明:随着碳纤维掺量的增加,混凝土质量损失率与抗压强度损失率呈现先下降后增加的趋势,其纤维掺量的拐点为1%;随着环境温度的上升,纤维混凝土的质量损失率与抗压强度损失率逐渐增加,并呈非线性增长趋势。随着静置时间的增加,混凝土抗压强度损失率逐渐增加,且呈非线性增长趋势。     

Research on multilevel information loss of the sharing process for safety information

To reveal the mechanism of information loss in the flow of safety information, and to derive an evaluation method for describing this information loss, this paper analyzes the flow of safety information based on research in safety informatics and cognitive psychology. Theoretical analysis shows that the flow of safety information can be divided into four stages: transformation, transmission, perception, and cognition. This paper describes a simplified model of the flow of safety information based on these four stages. Then, the concept of adaptive subjects is introduced, and the sources and losses of safety information are explored. In addition, a model of safety information flow loss is constructed. This model is used to analyze the connection between the information loss at each stage of the sharing process, and then a “ladder hierarchical” model for the loss of safety information is developed. Comprehensive analysis of this ladder hierarchical model of safety information leads to a formal mathematical model of safety information loss. Finally, according to the various development stages of the safety information sharing process, four key factors that affect the multilevel information loss of the safety information sharing process are extracted by the hierarchical method.     

风电机舱内典型混合液态油品热诱导燃烧特性

为探究不同尺寸方形油盘对双馈异步风力发电机组机舱中典型混合油品燃烧特性的影响,自主设计和搭建了热平板诱导油品加热燃烧测定实验系统。将液压油(CALTEXRANDO HDZ32)和齿轮箱油(CALTEXMEROPA320)按1∶1质量(各40.0g)比例均匀混合后,盛装于横截面尺寸分别为6.5cm×6.5cm、10.0cm×10.0cm、13.5cm×13.5cm 的钢制油盘中,利用热平板加热和诱导盘内同样质量混合油品燃烧,利用摄像机记录其燃烧行为和阶段节点时间,利用热电偶树、温度采集模块对油品燃烧对应阶段节点液内和上方火焰中心轴温度分布进行测定。观察发现,液/齿混合油品在加热后出现液内流动、蒸发、冒泡、气化、燃烧、发烟、火焰蹿高等典型传热传质和液相燃烧现象。实验结果表明,随油盘横截面尺寸递增,混合油品着火时间依次缩短(最高1048.0s),燃烧持续时间依次递减(最高1980.0s),燃烧液内最高温度依次升高(最高564.3 ℃),中心轴第一层火焰熄灭温度依次升高(最高489.2 ℃)。小尺寸油盘内油品交流换热过程缓慢,质量损失速率较低,着火前阶段出现最大质量损失速率(0.041g/s);中大尺寸油盘内对流、传质和传热过程明显增强,质量损失速率较高,火焰蹿高节点时出现最大质量损失速率(0.25g/s和0.29g/s)     

Sea salt bittern-driven forward osmosis for nutrient recovery from black water: A dual waste-to-resource innovation via the osmotic membrane process

• A dual “waste-to-resource” application of FO was proposed. • Performance of sea salt bittern as an economic FO draw solution was evaluated. • High quality struvite recovery from black water using FO was demonstrated. • Feed pH is a key factor to control the form of recovered phosphorous. A dual “waste-to-resource” innovation in nutrient enrichment and recovery from domestic black water using a sea salt bittern (SSB)-driven forward osmosis (FO) process is proposed and demonstrated. The performance of SSB as a “waste-to-resource” draw solution for FO was first evaluated. A synthetic SSB-driven FO provided a water flux of 25.67±3.36 L/m²⋅h, which was 1.5‒1.7 times compared with synthetic seawater, 1 M NaCl, and 1 M MgCl₂. Slightly compromised performance regarding reverse solute selectivity was observed. In compensation, the enhanced reverse diffusion of Mg²⁺ suggested superior potential in terms of recovering nutrients in the form of struvite precipitation. The nutrient enrichment was performed using both the pre-filtered influent and effluent of a domestic septic tank. Over 80% of phosphate-P recovery was achieved from both low- and high-strength black water at a feed volume reduction up to 80%‒90%. With an elevated feed pH (~9), approximately 60%‒85% enriched phosphate-P was able to be recovered in the form of precipitated stuvite. Whereas the enrichment performance of total Kjeldahl nitrogen (TKN) largely differed depending on the strength of black water. Improved concentration factor (i.e., 3-folds) and retention (>60%) of TKN was obtained in the high-nutrient-strength black water at a feed volume reduction of 80%, in comparison with a weak TKN enrichment observed in low-strength black water. The results suggested a good potential for nutrient recovery based on this dual “waste-to-resource” FO system with proper management of membrane cleaning.