对热压复合PVC塑料地板砖加热长度变化率的探讨

加热长度变化率是国家标准规定的塑料地板砖的物理性能指标之一,目前不少产品此项指标未能达到国家标准。分析了原因,提出了从工艺着手降低加热长度变化率的方法,以及加热长度变化率的简易鉴定方法。     

工程变更的分类控制

首先依据工程变更内容将工程变更划分为工作范围变更、施工条件变更、设计变更、施工变更和技术标准变更,对不同内容的变更区别情况提出不同控制方法。其次,依据工程变更性质将工程变更划分为重大变更、重要变更和一般变更,通过建立不同变更审批权限控制工程变更。最后依据工程变更的迫切性将工程变更划分为紧急情况下的变更和非紧急情况下的变更,通过设定不同变更处理程序进行控制。     

楼栋调压器出口压力波动的探讨

根据实测数据探讨了楼栋调压器出口压力的波动情况。     

基于状态空间模型的“一带一路”遗产 廊道生态旅游承载力研究

基于状态空间模型,综合生态环境、旅游资源和社会经济3个子系统对生态旅游的影响效果,以"一带一路"上的普洱"茶马古道"为例,构建了分层次的遗产廊道生态旅游系统承载力评价模型。针对不同文化遗产类型,采用GIS技术将各影响因子空间化,最后综合得到生态旅游承载力空间分异结果。研究结果表明:普洱市生态旅游承载力较低,仅有14.1%的区域具备强承载力,其余区域为较强承载、中等承载、较弱承载和弱承载等其他等级。研究可为"一带一路"等类似线性文化遗产旅游可持续发展的战略制定奠定理论和方法基础。     

Wind tunnel modeling of hourly observed atmospheric diffusion by oscillating blade cascade

Horizontal plume spread increases greatly with averaging time. For hourly averaging, plume spreads are much greater in the horizontal direction than in the vertical. The ratio of horizontal to vertical spread was found to be as large as 6. Conventional method cannot reproduce such anisotropic diffusion characteristic in wind tunnel experiments. The author has developed an oscillating blade cascade as a solution to the problem. Since the blade cascade generates strong secondary flow in the test section, a horizontal wind fluctuation of more than 11° has been achieved, which is similar to the standard deviation of wind direction averaged over 1 h under neutral condition.Distributions of mean wind velocity, turbulence intensity, and spectral structures were also similar to those observed in the atmospheric boundary layer.Hourly-averaged plume spread in horizontal and vertical directions could be simulated in the wind tunnel on 1:5000 scale, with appropriate selection of random motion amplitude of the blade cascade and ground roughness arrangement. Thus, the oscillating blade cascade method is useful to model large-scale plume diffusion from a continuous source such as thermal power plant stacks.     

小城镇规模与用水量变化规律研究

针对小城镇给水规划中用水量确定不合理的现象，实地调查了10个区域的典型小城镇群（300个样本）1998年—2004年的用水量，采用“二次平均法”计算了不同规模的小城镇人均综合用水量水平。调研统计结果表明，各类小城镇用水日变化系数较大，建议取值为1.75～1．95；各类小城镇用水高峰出现的时间大致相似，但最高峰值与最低峰值之间的振幅随小城镇的规模减小而增大，时变化系数宜取2．0～2．4，小城镇规模越小或生产用水比例低时取高值，基本无生产用水的可适当放大。     

渤海湾地基土随机场特性及可靠度分析

阐述了随机场理论在进行海洋结构物地基可靠度分析中的作用。利用渤海油田在多年开发和建设中积累的大量工程地质资料,开发研制了“海洋土地基可靠度分析系统”。运用该系统的强大数理统计和分析功能,综合理论和实测数据建立起渤海海域海洋土竖直和水平向土性剖面的齐次正态随机场模型,计算得到土性指标的方差折减函数,进而在可靠度分析中运用强度指标的空间平均方差进行可靠度分析,强度指标折减前后的可靠度分析结果表明随机场理论的应用对可靠度分析起到了重要的作用,经过折减的土性指标的变异系数明显较小,从而使可靠度分析的结果接近工程实际。     

自适应非局部3维全变分彩色图像去噪

目的 许多彩色图像去噪算法未充分利用图像局部和非局部的相似性信息,并且忽略了真实噪声在彩色图像不同区域内分布的差异,对不同图像块和不同颜色通道都进行同等处理,导致去噪图像中同时出现过平滑和欠平滑现象。针对这些问题,本文提出一种自适应非局部3维全变分去噪算法。方法 利用一个非局部3维全变分正则项获取彩色图像块内和块间的相似性信息,同时在优化模型的保真项内嵌入一个自适应权重矩阵,该权重矩阵可以根据每次迭代得到的中间去噪结果的剩余噪声来调整算法在每个图像块、每个颜色分量以及每次迭代中的去噪强度。结果 通过不同的高斯噪声添加方式得到两个彩色噪声图像数据集。将本文算法与其他6个基于全变分的算法进行比较,采用峰值信噪比(peak signal-to-noise ratio,PSNR)和结构相似性(structural similarity, SSIM)作为客观评价指标。相比于对比算法,本文算法在两个噪声图像数据集上的平均PSNR和SSIM分别提高了0.161.76 dB和0.12%6.13%,并获得了更好的图像视觉效果。结论 本文去噪算法不仅更好地兼顾了去噪与保边功能,而且提升了稳定性和鲁棒性,显示了在实际图像去噪中的应用潜力。     

Seasonal cycle of VOCs in apartments

To assess the adverse health effects of volatile organic compounds (VOCs), epidemiological studies combine the health outcome of individuals with their concomitant VOC exposure. While the latter is representative of the studied period, health effects might also be the result of long-term exposure or emerge in consequence of a peak pollution throughout the year. To address these problems, additional information about the spatiotemporal distribution of VOCs is necessary. The present paper aims at elucidating the spatial and temporal variation of VOC concentrations in Leipzig, Germany. The analysis is based on 1499 indoor and 222 outdoor measurements taken in the period between 1994 and 2001. All data were collected in the frame of epidemiological studies (Diez et al., 1999; Fritz et al., 1998; Schulz et al., 1999). The analysis comprised concentrations of 30 VOCs belonging to the groups of alkanes, cycloalkanes, aromatics, volatile halogenated hydrocarbons, and terpenes. We found that the VOC load in indoor air is, on average, 10 times higher than outdoors. For the studied period there was a clear downward tendency for all VOCs in apartments in Leipzig, except for terpenes which show an upward trend in the period 1996-99. In indoor air we observe an annual cycle for the total VOC concentration as well as the sum concentrations of the above called groups. Highest concentrations occur during the winter months, approximately three times higher than the summer burden. We summarize this finding in a seasonal model, which is fitted to our measurements. Based on the model we develop a procedure for seasonal adjustment, which enables to roughly estimate the annual peak concentration utilizing one monthly observation.     

再生粗骨料取代率对混凝土抗压强度的影响

通过试验室条件下371块立方体试块抗压强度试验,研究了再生粗骨料取代率分别为0,30%,50%,100%(质量分数)的混凝土抗压强度的变异特性及概率分布特征.基于试验数据,得到了不同再生粗骨料取代率混凝土抗压强度的均值、方差和变异系数;采用正态分布模型对再生混凝土抗压强度的分布进行了检验;利用Monte-Carlo模拟方法对根据试验结果得到的分布规律进行了进一步验证.研究结果表明,再生混凝土抗压强度的变异系数与普通混凝土差别不大;可以用正态分布模型描述再生混凝土抗压强度的概率分布.最后根据统计分析和贝叶斯估计结果,建议了C30再生混凝土抗压强度的标准差取值.