石油加工业二氧化硫产排污系数验证研究——以济南某石化企业为例

确保主要行业主要污染物排放总量数据的准确性对制定总量减排和区域环境质量改善规划尤为重要.以济南某石化企业为例,对石油加工业常减压、催化裂化、延迟焦化、柴油加氢、硫磺回收等工艺二氧化硫产排污系数开展验证研究.将产排污系数与监测结果对比分析,发现该企业通过产排污系数计算的二氧化硫排放量远大于实际排放量.在此基础上,提出石油加工业二氧化硫产排污系数修订建议.     

障碍物对瓦斯煤尘爆炸火焰传播规律的影响

为了进一步探究瓦斯煤尘耦合爆炸火焰的传播规律,用自行搭建的半封闭垂直管道爆炸试验系统,研究障碍物对瓦斯煤尘耦合爆炸火焰传播规律的影响。研究结果表明:障碍物能显著提高瓦斯煤尘爆炸火焰的传播速度,其加速机理主要是障碍物诱导的湍流区会促进火焰的传播;火焰在传播过程中的加速度不是一直增加,随着火焰速度的增加会出现上下波动;煤尘的加入会使瓦斯爆炸产生的火焰传播速度显著增大及速度的最大值距离点火端较远;通过障碍物时爆炸产生的火焰形状发生较大的改变,出现拉伸和褶皱现象。     

圆拱形缺陷对砂岩力学特征影响的试验研究

为研究含圆拱形预制缺陷砂岩的力学特征,在板状黄砂岩试样内预制了不同α值的圆拱形缺陷。采用YNS-2000型电液伺服控制试验系统和数字照相采集系统研究了不同圆拱形缺陷倾角α对黄砂岩力学特征和破坏模式的影响规律。研究结果表明:试样峰值强度、平均模量和割线模量随着α的增大呈先减小后增大再减小趋势,α=30°试样峰值强度和峰值应变均最小,α=75°试样峰值强度和应变均达到最大;预制圆拱形缺陷α对试样起裂应力、起裂位置和破坏模式均具有重要影响,随着α值的增大,试样起裂应力总体呈先减小后增大再减小趋势,当α=30°时,试样的平均起裂应力最小,其值为10.90 MPa;当α=75°时,试样的平均起裂应力最大,其值为18.91 MPa。     

A parametric model of child body shape in seated postures

Objective: The shape of the current physical and computational surrogates of children used for restraint system assessments is based largely on standard anthropometric dimensions. These scalar dimensions provide valuable information on the overall size of the individual but do not provide good guidance on shape or posture. This study introduced the development of a parametric model that statistically predicts individual child body shapes in seated postures with a few given parameters.

Methods: Surface geometry data from a laser scanner of children ages 3 to 11 (n = 135) were standardized by a 2-level fitting method using intermediate templates. The standardized data were analyzed by principal component analysis (PCA) to efficiently describe the body shape variance. Parameters such as stature, body mass index, erect sitting height, and 2 posture variables related to torso recline and lumbar spine flexion were associated with the PCA model using regression.

Results: When the original scan data were compared with the predictions of the model using the given subject dimensions, the average root mean square error for the torso was 9.5 mm, and the 95th percentile error was 17.35 mm.

Conclusions: For the first time, a statistical model of child body shapes in seated postures is available. This parametric model allows the generation of an infinite number of virtual children spanning a wide range of body sizes and postures. The results have broad applicability in product design and safety analysis. Future work is needed to improve the representation of hands and feet and to extend the age range of the model. The model presented in this article is publicly available online through HumanShape.org.     

废旧电路板破碎机设计研究

电路板因为具有韧性高、多组分的特性,在处理过程中不易被破碎。辊式破碎机具有结构简单、工作可靠、能耗低等特点,可用于废旧电路板的粗碎环节。该类辊式破碎机主要由电机、减速器、轴、齿辊、齿轮等组成,齿盘的齿牙形状、尺寸、排列可按电路板物料性质进行设计。首先通过设计计算并使用UG NX软件建立虚拟样机,分析了片状物料在破碎中受力情况;再使用Nastran模块对辊式破碎机的重要部件齿盘进行有限元分析,得出齿盘上承受载荷比较大的位置并对此提出了强化措施。     

城市生活垃圾处理全过程的低碳模式优化研究

生活垃圾处理过程中的温室气体排放是重要的人为碳排放源.本文提出一种基于城市生活垃圾处理全过程的低碳模式制定方法,通过对不同垃圾末端处理工艺的资源与能源消耗,温室气体排放潜值与资源化率的评价,进行处理情景设计与分析,识别出生活垃圾处理低碳发展的调控措施,并结合约束条件下的定量优化,得到生活垃圾低碳优化处理模式.最后,以北京市为案例点,针对主要调控因子设计不同无害化处理比例的3种情景并开展以上3方面评价.结果表明,垃圾低碳优化处理的措施为降低填埋比例,同时提高堆肥和焚烧比例;垃圾低碳优化处理模式为填埋、焚烧与堆肥的利用比例是23%:25%:52%.     

水下导弹发射装置结构材料应用研究

介绍了英国朴次茅斯大学对水下导弹发射装置的外形设计与材料应用研究。通过对材料的具体分析,结果表明,该水下发射装置较之目前正在采用的常规水面导弹发射装置更不易为敌方所侦测,即使通过声纳装置也难以侦测到。     

Physical and motor development in male and female rat offspring prenatally exposed to gamma radiation

Abstract

The effects of radiation on physical and motor development of male and female rats exposed to ionizing radiation in utero were studied. Rats were exposed to three different doses of radiation (150 rad, 15 rad and 6.8 rad, considered as high, moderate and low doses of radiation respectively) on the 20th day of prenatal life. Exposure to 150 rad contributed to significantly lower body weights of both male and female rat offspring. Upper jaw tooth eruption was delayed in 150 rad treated male offspring, as well as in 15 rad and 150 rad treated female offspring. Cliff‐avoidance response was delayed in 6.8 rad, 15 rad, and 150 rad treated male offspring; and 150 rad treated female offspring. Lower jaw tooth eruption, eye opening, and crawling were not affected by radiation in male or female animals. Results indicate that radiation affected the developmental parameters of both male and female rat offspring, and sex of the offspring played no role in the magnitude of radiation induced damages.     

Inferring Hydrograph Components from Rainfall and Streamflow Records Using a Kriging Method-Based Linear Cascade Reservoir Model1

Cheng, Shin-jen, 2010. Inferring Hydrograph Components From Rainfall and Streamflow Records Using a Kriging Method-Based Linear Cascade Reservoir Model. Journal of the American Water Resources Association (JAWRA) 46(6):1171–1191. DOI: 10.1111/j.1752-1688.2010.00484.x Abstract: This study investigates the characteristics of hydrograph components in a Taiwan watershed to determine their shapes based on observations. Hydrographs were modeled by a conceptual model of three linear cascade reservoirs. Mean rainfall was calculated using the block Kriging method. The optimal parameters for 42 events from 1966-2008 were calibrated using an optimal algorithm. Rationality of generated runoffs was well compared with a trusty model. Model efficacy was verified using seven averaged parameters with 25 other events. Hydrograph components were characterized based on 42 calibration results. The following conclusions were obtained: (1) except for multipeak storms, a correlation between base time of the surface runoff and soil antecedent moisture is a decreasing power relationship; (2) a correlation between time lag of the surface flow and soil antecedent moisture for single-peak storms is an increasing power relationship; (3) for single-peak events, times to peak of hydrograph components are an increasing power correlation corresponding to the peak time of rainfall; (4) the peak flows of hydrograph components are linearly proportional to that of total runoff, and the peak ratio for the surface runoff to total runoff is approximately 78 and 13% for subsurface runoff to total runoff; and (5) the relationships of total discharges have direct ratios between hydrograph components and observations of total runoffs, and a surface runoff is 60 and 32% for a subsurface runoff.     

Assessment of four turbulence models in simulation of large-scale pool fires in the presence of wind using computational fluid dynamics (CFD)

Pool fires are the most common of all process industry accidents. Pool fires often trigger explosions which may result in more fires, causing huge losses of life and property. Since both the risk and the frequency of occurrence of pool fires are high, it is necessary to model the risks associated with pool fires so as to correctly predict the behavior of such fires.Among the parameters which determine the overall structure of a pool fire, the most important is turbulence. It determines the extent of interaction of various parameters, including combustion, wind velocity, and entrainment of the ambient air. Of the various approaches capable of modeling the turbulence associated with pool fires, computational fluid dynamics (CFD) has emerged as the most preferred due to its ability to enable closer approximation of the underlying physical phenomena.A review of the state of the art reveals that although various turbulence models exist for the simulation of pool fire no single study has compared the performance of various turbulence models in modeling pool fires. To cover this knowledge-gap an attempt has been made to employ CFD in the assessment of pool fires and find the turbulence model which is able to simulate pool fires most faithfully. The performance of the standard k–? model, renormalization group (RNG) k–? model, realizable k–? model and standard k–ω model were studied for simulating the experiments conducted earlier by Chatris et al. (2001) and Casal (2013). The results reveal that the standard k–? model enabled the closest CFD simulation of the experimental results.