考虑逆向物流的应急物资配置流程SPN建模分析

应急物资的高效快速配置是降低灾害损失和顺利实施应急救援的有力保障。应急逆向物流包括废旧物资的回收利用以及可重复利用物资的回收再利用,能起到缓解应急物资匮乏,减少环境污染的作用。本文根据随机Petri网理论,构建考虑逆向物流的应急物资配置模型,通过对同构于该模型的马尔可夫链进行仿真,求得各种状态的稳态概率,结合马尔可夫链性质对关键因素进行静态分析和动态分析;通过“雅安地震”的案例应用表明,当地震灾害发生时,此模型可以反映各因素对应急物资配置整体流程的影响,并通过数值变化趋势反映不同条件下应急物资配置的关键环节,可以为灾后救援和应急物资的利用提供理论支持。     

Gender and career success: A typology and analysis of dual paradigms

Despite women's advancements in the workplace, gender inequality persists. We classify and test two frameworks used to explain gender differences in career success: unequal attributes and unequal effects. The unequal attributes framework suggests that gender is related to other attributes, which result in unequal career outcomes for men and women (i.e., a mediated effect). The unequal effects framework suggests that even when men and women share the same attribute or circumstances, they are rewarded differently, such that individual attributes have unequal effects on career outcomes for men and women (i.e., a moderated effect). We collected survey data from a gender‐balanced sample of 394 business school alumni. Using structural equation modeling to test the unequal attributes framework, we found that work hours, career orientation, having a nonemployed spouse, and working in a predominantly female job were unequal attributes that explained gender differences in career success. Using multigroup path analysis to examine unequal effects, we found that being agentic, married, having children at home, and working in a predominantly female workplace had unequal effects in relation to career success for men and women. We find support for both models across three categories of career success antecedents (i.e., personal, family, and job attributes).     

Stochastic bycatch, informational asymmetry, and discarding

The existing literature (i) examines bycatch and discard behavior in a static framework and (ii) treats bycatch as a deterministic process uniform across vessels. Using a dynamic representative agent model in a two-stock resource, this paper explores strategic interactions between a social planner and two groups of harvesters, one of which imposes a stochastic “technological externality” (bycatch) on the other. In addition to limitations on entry and the number of trips taken in each industry, three bycatch control instruments are compared to the unconstrained case: taxes, trip limits, and value-based quotas. Implementation and enforcement costs aside, taxes dominate both types of quota, and value limits outperform trip limits by eliminating one type of discarding. In simulations, relative performance depends upon variance in the bycatch process, differences in the ex vessel prices of stocks, relative efficiency of the harvester types, and fixed costs on the trip and industry margins.     

城市生活垃圾的DSC和TGA分析与热值估算

利用微分扫描量热仪（ＤＳＣ）准确地测定了城市生活垃圾的含水率；热重分析仪（ＴＧＡ）测定了垃圾的水和低温下有机物总含量、难挥发性有机物和灼烧残渣的含量。根据量热和热量分析结果，可方便地计算垃圾的水和低温条件下易挥发性有机物含量，结合６０９种有机物的燃烧热，估算了垃圾的热值。     

耗散结构理论在土壤科学上应用途径的探索

本文根据耗散结构的基本理论，结合生产实践经验，提出了表征土壤肥力的非线性微分方程：＝（Ｋ－ｂ）ｘ－βｘ２Ｘ─土壤生物活性，ｔ─时间，Ｋ─生物繁殖系数，ｂ─生物死亡系数，β─生物饱和系数．解这个并不复杂的非线性微分方程，便可知道土壤是处于热力学分枝，还是耗散结构分枝．这对研究土壤肥力的动态变化、土壤肥力的分类、土壤的管理、土壤退化的防止等方面有着无法预测的应用前景．     

A General Model for Analyzing Data from Mark-recapture Experiments with an Application to the Pacific Halibut

A general model is developed to examine the patterns of the regional movement of tagged and released fish from mark-recapture experiments. It is a stochastic model that incorporates fishing mortality, natural mortality, fish movement, tag-shedding, and different rates of reporting. A likelihood function is constructed for estimating its parameters. We used this model to analyze data on the Pacific halibut from mark-recapture experiments conducted by the International Pacific Halibut Commission (IPHC), with a total of 36,058 releases from 1982 to 1986 and 5,826 recoveries from 1982 to 2000. We estimated their rates of movement among IPHC management areas, along with their instantaneous rates of natural and fishing mortalities. Our analysis revealed that fish movement was not significant among areas, with a resident probability of > 0.92. This lends support to the IPHC catch-at-age stock assessment model (which has no built-in movement components). The estimated instantaneous rate of natural mortality (0.198 year⁻¹) lies between that assumed in all IPHC stock assessments before 1998 (0.20 year⁻¹) and that from 1999 onwards (0.15 year⁻¹). The estimates of the instantaneous rates of fishing mortality were consistent with those from the IPHC stock assessment model. Received: April 2003 / Revised: May 2005     

合肥市典型交通干道大气苯系物的特征分析

为研究合肥市交通干道大气苯系物污染状况,采用自主研制的差分吸收光谱(DOAS)系统,于2016年3月期间对合肥市交通主干道大气苯系物(苯、甲苯、间二甲苯和邻二甲苯)以及常规污染物NO_2、SO_2等进行了连续观测.观测结果显示,观测期间苯、甲苯、间二甲苯和邻二甲苯的平均浓度分别为:21.7、63.6、33.9和98.7μg·m~(-3).与国内外其它城市比较显示,合肥市交通干道大气苯和甲苯的污染处于中等水平,二甲苯的污染较为严重.结合观测期的间风速风向、T/B特征比值以及与CO等污染物的相关性,对上述苯系物来源进行了分析,结果显示观测期间T/B值为0.8~4.5,苯、甲苯与CO的相关性系数R分别为0.55和0.34.表明机动车尾气排放是观测区域苯和甲苯的主要排放源之一,同时也受到周边工业园区排放的影响,二甲苯的主要排放源为观测地点北偏东方向的涂料行业工业园区.苯和甲苯的夜间高浓度峰值分析结果表明,夜间的高浓度苯和甲苯可能主要来源于观测地点周边工业园区的排放.观测区域苯系物的臭氧生成潜势(OFP)表现为邻二甲苯间二甲苯甲苯苯,其中二甲苯的OFP占总OFP的85%,表明周边工业园区的排放对该地区臭氧生成的贡献较大.     

不同类型降解地膜的热解特性及热动力学研究

采用差热分析 (DTA)法分析 1种普通地膜和 3种可降解地膜的组成 ,并对地膜的热解过程进行热动力学研究 .结果表明 ,4种地膜的差热曲线有许多相似 ,但也略有差异 ,说明降解膜与普通膜的基本组分相同 ,而添加组分不同 .各地膜热解的反应级数约为 0 93.各地膜热解活化能和指前因子的大小顺序均为 :普通膜 >光降解膜 >光钙型降解膜 >生物降解膜 .     

截断阀室水淹后管道沉降的防护技术研究

为了保证长输天然气管道的安全运行,需要对其截断阀室遭受水淹后管道的不均匀沉降行为进行研究。应用ANSYS软件建立了管土非线性接触模型,通过对其进行分析建立了沉降量与最大Von Mises应力和椭圆度之间的映射关系,结果表明:不均匀沉降对管道强度的影响更明显,二者间基本呈线性关系,最大Von Mises应力随着沉降量的增大而增大,根据第四强度理论便可确定管道失效时的极限沉降量。同时还探讨了管径、内压、壁厚、埋深对管道应力状态的影响,降低内压、增大壁厚以及减小埋深和管径均可降低不均匀沉降时管道的最大Von Mises应力,但其中管径和壁厚的变化对管道最大Von Mises应力的影响更为显著。预期研究结果可以为山区管道的实时监测与防护措施制定提供一定的技术支持。