基于光学的金属/复材混合结构热变形试验研究

本文开展了金属/复材混合结构壁板热变形的测试方法研究，针对混合结构从常温20℃到-55℃的热变形行为，采用非接触式光学测试技术获取整个温度历程的热屈曲变形参数，揭示了飞机温度包线下混合结构壁板的热屈曲变形规律。结论：结构离面位移变化是结构屈曲失稳的表现，壁板结构在降温过程中虽然产生屈曲失稳现象，但是结构仍可恢复至正常状态，并未产生后屈曲现象，结构变形的变化斜率在-15℃之后发生了巨大的变化，基本呈现线性关系。     

湿式电除尘器出口封头的强度计算

湿式电除尘器(WESP)是实现燃煤电场"超低排放"的有效技术之一,目前在国内应用处于起步阶段,对于WESP强度计算相关经验仍比较少,尤其是对于湿式除尘器出口封头的强度计算研究显得尤为重要。针对佛山某湿式电除尘器项目大型异型的出口封头,通过钢结构分析软件STAAD对其进行了强度计算与结构选型,提高了湿式电除尘器对于特殊场地工况的适用范围和技术竞争力,为湿式电除尘器结构概念设计提供了明确思路,为燃煤电厂PM_(2.5)高效治理技术提供了更多的选择。     

开发区土地集约利用评价——以辽宁炮台经济开发区为例

综合调查分析大连市炮台开发区土地集约利用现状,建立土地集约利用评价指标体系,利用特尔斐法确定指标权重,进而计算土地集约利用度,并分别从扩展潜力、结构潜力、强度潜力、管理潜力四个方面计算土地集约利用强度。综合分析土地集约利用度与土地集约利用潜力强度计算结果表明,炮台开发区土地集约度分值达到86．16％,土地集约利用水平较高,土地利用强度潜力较小。未来土地利用潜力主要为扩展潜力,不存在管理潜力,从而对炮台开发区未来发展土地集约利用提出相应建议与措施。     

能源视角下的云南省工业结构与增长分析

计算云南省工业各行业1999—2012年的能源强度均值,对能源强度均值进行聚类分析,将云南省工业行业依据能源强度大小分成五大类,求出能源视角下云南省工业在考察期内各期结构变化速度、结构偏离度和结构高级化,并进行解析。通过回归分析得出云南省工业增加值增长率与能源视角下的工业结构变化速度,结构偏离度和结构高级化程度呈负相关,其中结构高级化、结构偏离度与云南工业增加值增长率之间的相关性显著,认为云南省工业发展应在可持续下侧重较低能源强度产业的发展。     

基于响应面法的机械可靠性设计与仿真方法研究

为研究机械结构可靠性设计与仿真方法。本文基于应力-强度干涉模型,应用响应面法(RSM),充分考虑结构分析中各参数的随机分布特性,利用ANSYS-PDS模块对法兰进行结构可靠性仿真。仿真结果显示,在进行10000次循环模拟计算后,法兰的结构可靠度为92.9%,灵敏度分析显示屈服极限与压力对可靠性影响最大。证明基于响应面法的可靠性分析方法为机械结构优化及可靠性计算提供指导,具有一定的工程应用价值。     

广州港新沙港区板桩码头结构设计方案比选分析

介绍了广州港新沙港区板桩码头主要内力计算方法及常用软件,结合设计过程、工程地质情况、现场实际施工情况,着重从受力合理性、施工便利性、节省造价方面,对提出的钢板桩方案、钢管板桩方案进行比较分析,确定了钢管板桩结构更合理,并对优势进行总结。研究表明相对于钢板桩结构,钢管板桩结构在抗弯、抗变形、拉杆拉力和锚碇墙稳定性、对复杂地基（软弱土层较厚、岩层标高较高的地基）适应性、兼顾桩基基础、施工速度等方面更具备优势,且钢管板桩结构可更好的适应码头的大型化和深水化发展,在类似工程设计中可优先采用钢管板桩结构。     

基于LMDI法的湖南省碳排放强度影响因素解析

利用2005—2015年湖南省煤炭、石油、天然气三种主要能源的终端消费量,计算逐年碳排放量与碳排放强度,运用对数平均权重分解法(LMDI)探讨了产业结构、能源强度和能源结构对于碳排放强度的贡献率。结果表明:2005—2015年湖南省碳排放强度降低了0.339 t/万元。其中,能源强度对碳强度降低的贡献率最大,为94.5%,能源结构偏小,为16.4%,而产业结构抑制了碳强度的降低,贡献率为-10.9%。因此,湖南省节能减排应着重从优化产业结构、降低能源强度等方面着手。     

榄普一线500kV线路取消架空地线防雷性能分析

榄普一线500 k V线路由于地线覆冰严重,多次出现线路跳闸、地线断裂等事故,因此需要将架空地线取消。结合行波法和ATP-EMTP电磁暂态分析,对取消地线前后榄普一线的耐雷强度进行了仿真计算。计算结果表明,取消地线后雷击基本都变为绕击,并且绕击耐雷强度和反击耐雷强度均有所降低,需要采用其他防雷措施进行保护。     

基于备件分析的飞机最经济飞行强度选择

飞机作为航空产品,使用维护成本在全寿命周期费用中占据了相当大的比例。将使用维护成本折算为备件的采购和维修成本,在设计阶段通过基于备件的分析,分类计算在不同飞行强度下各种备件的采购和维修费用,从而确定飞机在满足用户需求的前提下所能执行的最经济的飞行强度。以某型飞机为例,提出了一种最经济飞行强度的计算方法,有助于在设计阶段规划飞机的使用和维护保障。     

冲击载荷下三点弯曲试样的有限元分析

对三点弯曲试样建立三维有限元分析模型,取其1／4模型进行有限元分析、计算出裂尖附近节点垂直于裂纹面的位移值,利用位移法计算出每节点相应的动态应力强度因子。将曲线外推到裂尖处即得到裂尖动态应力强度因子。结果表明裂尖动态应力强度因子值沿试样中部向表面逐渐减小,只要通过实验确定起裂时间,便可得到试样的动态起裂韧性。     

Changing Climate,Challenging Choices: Identifying and Evaluating Climate Change Adaptation Options for Protected Areas Management in Ontario,Canada

Climate change will pose increasingly significant challenges to managers of parks and other forms of protected areas around the world. Over the past two decades, numerous scientific publications have identified potential adaptations, but their suitability from legal, policy, financial, internal capacity, and other management perspectives has not been evaluated for any protected area agency or organization. In this study, a panel of protected area experts applied a Policy Delphi methodology to identify and evaluate climate change adaptation options across the primary management areas of a protected area agency in Canada. The panel identified and evaluated one hundred and sixty five (165) adaptation options for their perceived desirability and feasibility. While the results revealed a high level of agreement with respect to the desirability of adaptation options and a moderate level of capacity pertaining to policy formulation and management direction, a perception of low capacity for implementation in most other program areas was identified. A separate panel of senior park agency decision-makers used a multiple criterion decision-facilitation matrix to further evaluate the institutional feasibility of the 56 most desirable adaptation options identified by the initial expert panel and to prioritize them for consideration in a climate change action plan. Critically, only two of the 56 adaptation options evaluated by senior decision-makers were deemed definitely implementable, due largely to fiscal and internal capacity limitations. These challenges are common to protected area agencies in developed countries and pervade those in developing countries, revealing that limited adaptive capacity represents a substantive barrier to biodiversity conservation and other protected area management objectives in an era of rapid climate change.     

Investigation of modified horizontal wing cut twisted tapes fitted with rod and spacer at trailing edge on heat transfer properties in Double Glazing V-Trough solar water heaters

An experimental analysis of heat transfer efficiency in double glazing solar water heating system having full-length Horizontal wing cut twisted tapes having twist ratio 3 fitted with rod or spacer of dimensions 125 mm, 250 mm, and 500 mm as length at the trailing edges has been dealt in this work. The experimental results have been compared with a plain tube with similar operating conditions and concluded that variation in the Nusselt number, as well as friction factor, are ±12.56% and ±10.17%, respectively. The result of empirical correlation concludes that Nusselt number is maximal for horizontal wing cut twisted tapes having rod or spacer at its ends while comparing with full-length horizontal wing cut twisted tapes. The friction factor is low for full-length horizontal wing cut twisted tapes than the horizontal wing cut twisted tapes fitted with rod or spacer. The horizontal wing cut twisted tapes fitted with rod has superior performance than twist fitted with spacer.     

云南高原湖泊流域土地利用与水质变化异质性分析

以云南省九大高原湖泊为例,通过面板数据方式分析对高原湖泊流域土地利用类型变化,通过库兹涅兹曲线相关内容对利用强度的分析以及与水质的动态变化情况,得到耕地、园地、湿地面积与湖泊含磷量存在一定负相关.林地、牧草地、建设用地面积与湖泊含磷量存在一定正相关.牧草地、耕地、园地、湿地面积与湖泊含氮量存在一定负相关,建设用地面积与湖泊含氮量存在一定正相关.园地和耕地面积与污染综合指数存在负相关,建设用地面积与污染综合指数存在负相关.分析指出,滇池、泸沽湖处于流域协调区间,阳宗海、抚仙湖、星云湖、程海处于流域冲突区间,洱海、异龙湖处于冲突区间向协调区间转型过程中.     

汽车内饰件的自然暴晒试验

本文主要阐述汽车内饰件自然暴晒试验方法：IP／DP箱试验和整车暴晒试验。汽车内部材料的耐用性是影响使用满意程度的极其重要的因素,所以汽车内饰材料需要一个模拟其在具体使用过程中的自然条件的试验,以便观察汽车内饰件在老化过程中的性能变化。     

Are shocks to natural gas consumption transitory or permanent? A more powerful panel unit root test on the G7 countries

This article re‐examines the persistence in natural gas consumption using an alternative methodology. We compare the results of traditional panel unit root tests with those provided by Bahmani‐Oskooee et al., which allow for both sharp and smooth breaks. Our analysis uses data for the G7 countries over the 1965–2016 years. The empirical findings show that while traditional unit root tests with sharp breaks lean towards the non‐stationarity of the series for all the G7 countries, modeling breaks in our unit root testing methodology can assert that natural gas consumption is non‐stationary only for Canada, France, Italy, and USA. These results imply that, for the majority of our sample, energy demand management policies designed to shrink energy consumption will have temporary effects, as energy consumption will return to its trend path.     

论饮食业油烟治理技术的发展及应用

实际应用的饮食业油烟净化设备（以下简称油烟净化设备）中，以静电式、机械过滤式、湿式，以及由上述三种技术组成的复合式产品为主。荷电湿式油烟净化器的开发应用，将具有很强的市场竞争力，未来几年，静电式技术将继续被广泛采用，机械式技术将更多地作为预处理手段与其他技术组合使用，湿法技术因兼有部分除味和去除柴油灶燃烧颗粒的功能等特点将更有针对性地应用于适当的场所。优化组合而成的经济高效的复合式技术在未来市场中将占据主导地位。     

Reduction of pathogen indicator organisms in dairy wastewater using an ecological treatment system

Ecological treatment systems can provide a sustainable, plant-based alternative to traditional wastewater treatment. One factor essential to the success of these systems is ensuring their ability to reduce coliform concentrations in wastewater. Wastewater is the primary source of fecal contamination in aquatic ecosystems, containing total and fecal coliforms on the order of 10(8)-10(10) and 10(7)-10(9) CFU L(-1), respectively. This study assessed the ability of an ecological treatment system to reduce concentrations of total coliforms and Escherichia coli from dairy wastewater. Low strength wastewater was pumped into the system during July of 2005 and high strength in September 2005. Wastewater passes through a series of anaerobic, aerobic, and clarifier reactors and wetland cells before exiting the system. Regardless of wastewater strength, average total coliform and E. coli concentrations were consistently reduced by at least 99% from influent to effluent, with the majority of the reduction (76%) occurring in the first two reactors. Relationships between internal concentrations of solids and coliforms indicated that increased reduction of solids may further reduce coliform concentrations. Although U.S. Environmental Protection Agency discharge requirements for E. coli were not always met, the substantial reductions achieved indicate that ecological treatment systems have the potential to successfully reduce coliforms in wastewater to meet discharge limits. The results from this study will be used to guide design and management of future ecological treatment systems, so that larger and more consistent coliform reductions can be achieved.     

城沐一线500kV线路取消架空地线力学性能分析

架空地线的主要作用是防止雷电直击导线,但在冬季,由于架空地线线径较细,强度较低,多次因地线覆冰引发断线、跳闸事故,因此提出了取消重冰区500 k V线路架空地线的做法。使用有限元仿真工具ANSYS Workbench,以城沐一线500 k V线路三基杆塔为对象进行建模,对取消地线前后城沐一线的力学性能做了仿真计算。计算结果表明,在不同的覆冰强度下,取消地线后杆塔塔头及塔身主材所受拉力及应力都有所下降,提高了整个塔线体系在冬季运行的可靠性。结果可为冰区超高压电网的运行维护工作提供指导。     

Is there a Kuznets curve for cropland use? The evidence from international panel data

The environmental Kuznets curve (EKC) hypothesis assumes the nonlinear relationship between production and its environmental effects, suggesting that the negative effect of production on the natural environment is reversed at higher levels of development. In contrast to the majority of the studies, this paper considers the possibility of non-linear effects of per capita output on agricultural land use (cropland), as one of the natural resource stocks, and additionally examines the influence of demographic and productivity variables on the agricultural land use. The study draws on panel data from 143 economies over the 1990–2019 period and employs a series of panel econometrics techniques (including panel unit root and cointegration tests, panel ordinary least squares, generalized method of moments, and panel quantile models). The results unequivocally indicate the inverted U-shaped relationship between the GDP per capita and cropland use, as per EKC hypothesis. The results are robust with respect to employing different techniques, the identified turning points correspond to low and low-middle-income levels, and the effects of agricultural productivity and population density on land use are respectively negative and positive.