新旧桥梁承载能力评定对比研究

基于36座新建桥梁及26座既有旧桥静、动载试验,将其在荷载作用下挠度、应变及振动频率的现场实际值与有限元计算理论值进行对比分析,获取了新旧桥梁的挠度、应变及频率的检验系数,并在此基础上获取了新旧桥梁的承载能力对比情况。结果表明,既有旧桥承载能力下降明显。这将为类似桥梁检测及承载能力评估提供参考。     

基坑围护结构的内力和变形的预测方法研究

为了利用土体水平抗力系数的比例系数m来有效预测基坑围护结构的内力和变形,依据弹性地基梁原理,利用大型数学软件MATLAB编制了计算程序,对基坑围护结构的内力和变形进行预测,并依托某深基坑工程围护结构的实测内力和变形数据对预测的内力和位移进行了验证。结果表明,根据弹性地基梁原理预测的基坑围护结构内力和变形随基坑开挖的变化与实测结果吻合较好。     

Performance Enhancement of a Beta Type Rhombic Drive Stirling engine

ABSTRACT

Stirling engines maintain attraction because of their high energy conversion efficiencies. In this study, experimental comparison of a beta-type Stirling engine for two different rhombic-drive mechanisms was presented. In one of the rhombic mechanisms, spur gears were used and the gear shaft was supported in bearings from one side. In the other mechanism, two helical gears were placed on crankshafts and the crankshafts were supported in bearings from both sides. Rhombus lengths of the mechanisms were determined as 66 mm and 80 mm to provide same constant compression ratio of 2.5 for both configurations. Both mechanisms were used in the same beta-type Stirling engine having same cylinder, piston and displacer dimensions. Performance parameters of the engines were evaluated at different helium charge pressures (2–4 bar) and hot-end temperatures (400–600°C). The hot-end of the displacer cylinder was heated by a liquefied petroleum gas (LPG) burner. The engine power increased by 132%, friction losses and gear noses were reduced by supporting the rhombic-drive mechanism from both side and using helical gears. The maximum output torque and power of the engine were obtained as 13.14 Nm at 428 rpm engine speed and 663 W at 800 rpm engine speed, respectively, at 600°C hot-end temperature and 4 bar charge pressure.     

瑞利波法在检验复合地基效果中的应用

应用弹性波理论研究场地土物理特征,以瑞利波的基本原理与理论解释为基础,提出用瑞利波法测定场地土力学参数。该方法具有快速、经济、不受场地条件影响等特点,其成果与反映整个场地平面的原位测试结果几乎一致。实例分析说明了该法的实用性与可靠性,同时提出采用瑞利波法普查结合少数几组荷载板试验的方法,对整个场地的检测与评价将更为全面、准确和客观。     

PATTERNS OF WATERSHED MONTHLY RUNOFF1

ABSTRACT: Two dimensional sliding polynomials were adapted to pattern analysis of watershed monthly rainfall and runoff. Contours of runoff in the two-dimensional space of time and rainfall are constructed on a grid of 16 nodes whose values are determined by least squares. This method is form free, hence derived patterns are not biased to selected functional forms, but can directly represent the smoothed data. Values of the nodes are localized averages of the data constrained by required mathematical continuity across the grid of values. An advantage of the method is that the standard deviation can be calculated for each node, thus producing patterns of uncertainty of the deterministic component revealed by the data.     

溜砂坡遥感解译标志与方法——以川藏公路然乌-中坝段为例

溜砂坡是一种特殊的坡面堆积形式,主要发生在较为干旱的花岗岩山区,因其稳定性差,溜砂坡活动较为频繁,成为山区公路的重要灾害之一。以川藏公路然乌—中坝段为研究区,对溜砂坡的地貌形态和植被特征及其遥感影象特征进行了初步分析,确定了溜砂坡的遥感解译标志,并分析了溜砂坡和滑坡在遥感图像上的区别。将溜砂坡的遥感解译方法应用到川藏公路然乌—中坝段,查清了该路段的溜砂坡分布及其危害。     

模糊综合评判区域承灾体脆弱性的理论模型

灾害的后果是由致灾环境的危险性和承灾体的脆弱性两个因素共同决定的，承灾体的脆弱性研究对灾害理论以及减灾政策的确定有着极为重要的意义。承灾体脆弱性等级评价是该研究的基础和关键，本文建立了区域承灾体脆弱性模糊综合评判模型。     

煤巷顶板围岩结构承载能力弱化分析

为了揭示煤巷顶板围岩承载能力的弱化机理,结合已有的研究成果,建立巷道顶板三向承载梁结构承载弹塑流弱化分析模型,确定三向承载梁结构承载状态的分析方法,提出用围岩塑性区深度、宽度、长度作为评价巷道围岩承载的弱化分析指标,研究围岩性质、支护强度、采动应用等诱导因子对煤巷顶板结构承载能力弱化分析指标的影响规律。研究结果表明:随着围岩强度的提高、支护强度的增加、扰动应力的减小,弱化分析指标呈似线性减小的变化规律,且减幅由大到小排序为塑性区长度Sy,宽度Sx和深度Sz,同时提高围岩强度、支护强度,减小采动作用应力,煤巷顶板弱化分析指标的减小程度显著高于单因子的改善。     

PVC弹性填料生物膜法处理含H2S气体

采用ＰＶＣ弹性填料进行好氧生物膜法气体脱硫研究,结果表明,微生物挂膜速度快,驯化时间短,抗冲击负荷能力较强。在空速１００～２００ｈ＾－１,喷淋水量１０００～１５００Ｌ／（ｍ＾３．ｈ）、进气Ｈ２Ｓ质量浓度〈１２００ｍｇ／ｍ＾３时,Ｈ２Ｓ去除率达９０％以上。     

基于耦合协调度模型的河西走廊生态环境质量时空格局演化

以“丝绸之路”经济带上的河西走廊地区为研究对象,采用耦合分析法,构建环境承载力与生态弹性限度的耦合协调模型,在分析2001—2016年河西走廊生态环境承载力和生态弹性限度的基础上,探析河西走廊生态环境承载力与弹性限度的耦合协调度,评价生态环境承载力和生态弹性限度耦合协调阶段及区域生态环境质量水平,从区域和城市两个空间尺度分析生态环境耦合协调类型,为探索河西走廊生态环境可持续发展道路提供科学依据。结果表明:①2001—2016年,河西走廊生态环境承载力和生态弹性限度均呈现东南高、西北低的空间格局和缓慢波动上升趋势。②河西走廊生态环境耦合协调度呈现“东南高西北低,优劣破碎穿插”的空间格局特征,耦合协调度在0~0.5之间,生态系统处于低水平和拮抗耦合阶段,生态环境质量处于濒临失调阶段。③河西走廊生态环境承载力与生态弹性限度耦合协调度存在明显区域差异。河西走廊生态环境耦合协调度共分9个等级3个层次3个耦合协调阶段:高水平-磨合阶段区(良好协调、中度协调和初级协调区);中等水平-拮抗耦合阶段区(勉强协调、濒临失调和轻度失调区)和低水平区-低水平耦合阶段区(极度失调、严重失调和中度失调区)。④根据2001—2016年生态环境耦合协调状况将河西走廊五市分为4种耦合协调类型:高耦合协调增长型(张掖市、金昌市)、高耦合协调减少型(武威市)、中耦合协调增长型(嘉峪关市)和低耦合协调增长型(酒泉市)。各地区应因地制宜地制定发展战略,提高生态环境质量,推进生态环境持续协调发展。