生活垃圾协同水葫芦干式厌氧发酵制沼气的研究

探讨了水葫芦和生活垃圾在中温条件下联合发酵的可行性,研究了系统总固体含量(TS)、发酵母液添加比例(IR)以及水葫芦添加比例(WR)对厌氧发酵过程的影响。试验结果表明,添加5%的水葫芦能够有效防止因TS和IR的变化对系统pH值所带来的影响,缩短发酵启动时间,使产气高峰集中出现,并提高产气量。但是当水葫芦添加比例增加到10%时,沼气产量反而下降。发酵70 d后,挥发性固体(VS)降解率为38.18%～58.10%。通过对正交试验结果进行分析,得到水葫芦与生活垃圾联合发酵制沼气的较优工艺条件为:系统总固体含量23%,发酵母液添加比例100%,水葫芦添加比例5%。     

转向螺母锻模块液态模锻工艺分析及模具设计

此文叙述了转向螺母锻模块液态模锻工艺及特点,对该工艺及模具设计作了较详细的分析研究。     

基于正交分析的防烟缓冲区参数设置研究

为了研究典型长廊型高层建筑中走廊-前室缓冲区不同参数设置对烟气控制的影响,利用FDS软件建立长廊型高建筑火灾烟气运动模型。利用空气幕配合正压送风在前室门前形成防烟缓冲区,运用正交设计的方法分析流量比、空气幕射流速度以及空气幕射流角度对缓冲区防烟能力的影响,得出防烟缓冲区最佳模式为空气幕送风量与前室加压送风量之比为2∶1,空气幕射流速度为8 m/s,空气幕射流角度为30°。与传统正压送风防烟模式相比,防烟缓冲区最佳模式下,前室的平均CO浓度降低了99.99%,平均温度降低了98.47%,防烟缓冲最佳模式使前室加压送风量减少了1/3,楼梯间加压风量减少22.56%,节约了送竖井的地面积,减少了进入走廊和火场区的送风量,使排烟效率提高了8.76%。     

民用飞机客舱个人通风喷嘴布置研究

目的 获得民用飞机客舱个人通风喷嘴的最佳布置方案.方法 针对下拉式行李箱的客舱布局,建立单排客舱个人通风的k-ε模型,使用ICEM CFD进行网格划分.梳理并分析国内外个人通风的标准手册,将人体头部高度处的风速大于1 m/s作为设计指标.提出2种喷嘴布置方案——分散布置和集中排列布置,设计5种工况,运用FLUENT软件...     

基于低影响开发的雨洪管理研究现状和趋势研究

降雨径流是影响城市河流水质以及发生内涝的主要原因之一,传统的雨水管理模式已经不能适应现代城市的发展,低影响开发是基于模拟自然水文状况的原理,采用源头控制来消减、利用和延缓径流以及控制径流污染的一种分散的、多样性的、景观化的微型控制单元。国内低影响开发的工程实践还比较少,在借鉴国外有关低影响开发的设计方法、效果监测以及模型模拟方面的理论同时,国内还需要开展长期效果监测来建立自己的设计参数数据库以及研究适合国内的设计决策支持工具。     

《计算机操作系统》试题库系统的设计与实现

根据现代教育理念与技术的要求,结合《计算机操作系统》课程的教学实际,应用VB 6.0编程语言和SQL Server 2000数据库,开发了《计算机操作系统》试题库系统,实现教考分离,解决了人工出题的随机性。本文介绍了试题库的功能设计、数据库表设计、自动抽题策略、Word试卷组成等技术,具有很强的通用性和可操作性。     

A virtual test system representing the distribution of pedestrian impact configurations for future vehicle front-end optimization

Objectives: The purpose of this study is to define a computationally efficient virtual test system (VTS) to assess the aggressivity of vehicle front-end designs to pedestrians considering the distribution of pedestrian impact configurations for future vehicle front-end optimization. The VTS should represent real-world impact configurations in terms of the distribution of vehicle impact speeds, pedestrian walking speeds, pedestrian gait, and pedestrian height. The distribution of injuries as a function of body region, vehicle impact speed, and pedestrian size produced using this VTS should match the distribution of injuries observed in the accident data. The VTS should have the predictive ability to distinguish the aggressivity of different vehicle front-end designs to pedestrians.

Methods: The proposed VTS includes 2 parts: a simulation test sample (STS) and an injury weighting system (IWS). The STS was defined based on MADYMO multibody vehicle to pedestrian impact simulations accounting for the range of vehicle impact speeds, pedestrian heights, pedestrian gait, and walking speed to represent real world impact configurations using the Pedestrian Crash Data Study (PCDS) and anthropometric data. In total 1,300 impact configurations were accounted for in the STS. Three vehicle shapes were then tested using the STS. The IWS was developed to weight the predicted injuries in the STS using the estimated proportion of each impact configuration in the PCDS accident data. A weighted injury number (WIN) was defined as the resulting output of the VTS. The WIN is the weighted number of average Abbreviated Injury Scale (AIS) 2+ injuries recorded per impact simulation in the STS. Then the predictive capability of the VTS was evaluated by comparing the distributions of AIS 2+ injuries to different pedestrian body regions and heights, as well as vehicle types and impact speeds, with that from the PCDS database. Further, a parametric analysis was performed with the VTS to assess the sensitivity of the injury predictions to changes in vehicle shape (type) and stiffness to establish the potential for using the VTS for future vehicle front-end optimization.

Results: An STS of 1,300 multibody simulations and an IWS based on the distribution of impact speed, pedestrian height, gait stance, and walking speed is broadly capable of predicting the distribution of pedestrian injuries observed in the PCDS database when the same vehicle type distribution as the accident data is employed. The sensitivity study shows significant variations in the WIN when either vehicle type or stiffness is altered.

Conclusions: Injury predictions derived from the VTS give a good representation of the distribution of injuries observed in the PCDS and distinguishing ability on the aggressivity of vehicle front-end designs to pedestrians. The VTS can be considered as an effective approach for assessing pedestrian safety performance of vehicle front-end designs at the generalized level. However, the absolute injury number is substantially underpredicted by the VTS, and this needs further development.     

建筑,消融于环境——基于消融性的建筑造型设计手法探析

站在环境美学的角度,从建筑造型形态入手,研究建筑如何实现与环境的相互消融。在明确消融性意义的基础上,通过实例论证和分析总结的方法,从地形消融和元素消融等两方面进行具体阐明,在建筑与环境的矛盾日益突出的情况下,以期为二者的融合找到契合点,进而创造环境的建筑,实现环境美并为建筑造型的设计提供一定的参考和借鉴。     

Recovery of copper from small grain size fractions of municipal solid waste incineration bottom ash by means of density separation

Small grain size fractions of municipal solid waste incineration (MSWI) bottom ash (BA) contain elemental and chemically bonded metals in appreciable amounts, especially copper. Investigations with a centrifugal concentrator were carried out using samples, which had been treated with different impact devices. Partly the impacts of single devices were visible in outlines, but mostly the surfaces of the metals were still covered with mineral residues. To generate copper rich fractions, parameters of the separation process should ensure mass yields <2%, best between 0.5 and 1%. The density of the concentrates is then generally >3.2 g/cm³. Best results were achieved with material from a special treatment train which is adapted to grain sizes <2 mm. Reliable copper contents between 20 and 40% (single runs >50%) could be realised. However, considering the required mass yields, referred to this subset only 150–170 g copper would be recovered from 1 Mg MSWI BA. Furthermore, this copper is only in parts present in elemental form. A dependable added value of such treatment step seems to be given only, if that enables a recycling of the mineral aggregates (tailings) in parallel to avoid landfill costs.     

Optimal allocation procedure in ranked set sampling for unimodal and multi-modal distributions

This paper presents a ranked set sample allocation procedure that is optimal for a number of nonparametric test procedures. We define a function that measures the amount of information provided by each observation given the actual joint ranking of all the units in a set. The optimal ranked set sample allocates order statistics by maximizing this information function. This paper shows that the optimal allocation of order statistics in a ranked set sample is determined by the location of the mode(s) of the underlying distribution. For unimodal, symmetric distributions, optimal allocation always quantifies the middle observation(s). If the underlying distribution with cdf F is a multi-modal distribution with modes , then the optimal allocation procedure quantifies observations at in a set of size m. We provide similar results for unimodal, asymmetric distributions. We also propose a new sign test which considers the relative positions of the quantified observations from the same cycle in a ranked set sample. The proposed sign test provides improvement in the Pitman efficiency over the ranked set sample sign test of Hettmansperger (1995). It is shown that the information optimal allocation procedure induced by Pitman efficiency is equivalent to the optimal allocation procedure induced by the information criteria. We show that the finite sample distribution of the proposed test based on this optimal design is binomial.