Parametric Study by Dynamic Simulation of the Influence of the Air Infiltration Rate and the Convective Thermal Transfer Coefficient on the Thermal Behavior of Residential Buildings Built with Cut Lateritic Blocks

Sustainable building design in dry tropical areas recommends reducing exposure of buildings to solar radiation and/or designing efficient enclosures with satisfactory thermal inertia.We propose in this paper a study of the influence of the infiltration rate in the building and the coefficient of thermal transfer by convection of the walls, on the thermal comfort using TRNSYS software. All the models carried out were validated by recognized scientific criteria, namely correlation （R） and determination （R2） coefficients on the one hand and NBME and CVRMSE coefficients defined by ASHARE, 2002 on the other hand. The results obtained indicate that the modulation of the air infiltration rate allows the simulations on TRNSYS to be compared to in-situ measurements, with an annual average relative difference of 2.86% on the temperature difference. Furthermore, depending on the parameterization of the heat transfer coefficients by convection of the internal and external walls of walls used in the STD, the average annual difference can be reduced by 1% to 4% between the predictions and the measurements.

Decomposition in blocks at the level of wavelet coefficients and T（1 ） theorem on Hardy space

This paper deals with the establishment of \%T(1)\% theorem on Hardy space \%H 1\% under condition of weak regularity. An operator or a function is identified on the basis of their wavelet coefficients which are regrouped on some blocks. The actions of each block operator (pseudo\|annular operator) on each block function (atom) are exactly analyzed to establish \%T(1)\% theorem on Hardy space.

Early all-zero blocks detecting method for video coding based on novel threshold

In order to decrease both computational complexity and coding time, an improved algorithm for the early detection of all-zero blocks （AZBs） in H. 264/AVC is proposed. The previous AZBs detection algorithms are reviewed. Three types of transformed frequency-domain coefficients, which are quantized to zeros, are analyzed. Based on the three types of frequencydomain scaling factors, the corresponding spatial coefficients are derived. Then the Schwarz inequality is applied to the derivation of the three thresholds based on spatial coefficients. Another threshold is set on the basis of the probability distribution of zero coefficients in a block. As a result, an adaptive AZBs detection algorithm is proposed based on the minimum of the former three thresholds and the threshold of zero blocks distribution. The simulation results show that, compared with the existing AZBs detection algorithms, the proposed algorithm achieves a 5% higher detection ratio in AZBs and 4% to 10% computation saving with only 0. 1 dB video quality degradation.

AN IMPROVED ALL ZERO BLOCK FINDING METHOD BASED ON THE STATISTIC CHARACTERISTICS OF DCT TRANSFORM COEFFICIENTS

In the H.263 video codec related systems, motion estimation and Discrete Cosine Transform (DCT) have the most computational requirements. In order to reduce complexity of the encoder to dedicate more resources to other functions, according to the study of existing methods, an Improved All Zero Block Finding (IAZBF) method based on the statistic characteristics of DCT coefficients is proposed. Compared with existing methods, IAZBF improves the detecting efficiency by about 50% without importing too much extra computation requirement. Being computed with additions and shifts instead of complicated multiplications, IAZBF is of low computation complexity, especially for low-end processors. In addition, IAZBF upholds picture fidelity and remains compatible with the H.263 bitstream standard.

Reflection and transmission properties of double submerged rectangular blocks

An analytic method is used to study the reflection and transmission coefficients of the double submerged rectangular blocks （DSRBs） in oblique waves. The scattering potentials are obtained by means of the eigenfunction expansion method, and expressions for the reflection and transmission coefficients are determined. The boundary element method is employed to verify the correctness of the present analytical method. The DSRBs have better performance than the single submerged rectangular block （SSRB） in certain cases. The reflection and transmission properties of the DSRBs are investigated for some specific cases, and the influences of the geometric parameters are also presented.

A new all-zero 4×4 block determination rule for integer transform and quantization in AVS-M encoder

A new all-zero block determination rule was used to reduce the complexity of the AVS-M encoder. It reuses the sum of absolute difference of 4x4 block obtained from motion estimation or intra prediction as parameters so that the determination threshold need to be computed only once when quantization parameter (QP) is invariable for given video sequence. This method avoids a lot of computation for transform, quantization, inverse transform, inverse quantization and block reconstruction. Simulation results showed that it can save about 20%～50% computation without any video quality degradation.

A PREDICTION BASED ALL-ZERO BLOCK DETECTION METHOD FOR H.2G3

In this letter, a novel method based on Temporal and Spatial Prediction (TSP) to detecl all-zero DC.'T coefficients based on temporal and .spatial prediction between neighboring blocks is proposed. The presented algorithm uses the knowledge of all-zero block distribution in the previous frame combined with the Sum of Absolute Difference (S.AD) of the corresponding macroblock as a. criterion. The algorithm almost needs no additional computation, and it. shows an excellent overall detection performance in simulations.

Experimental Study of the Behaviour of Lime-Stabilized Clay Soil Blocks by Simple Compression for Wall Construction

This study addresses an experimental approach to stabilizing clay soils with lime.In the preliminary stage and in order to require characteristic properties,untreated clay and sand samples are collected on site and subjected to laboratory identification tests.Then,the so-called“trial and error”process based on production test series is used to mix with water by varying the proportions of the constituents.Using a manual press with a capacity of 5 to 10 tonnes,equipped with a 10×15×28 cm^(3) mould,the free-standing and heavy blocks are produced from the firm mixtures retained.After cures of 7,14 and 28 days,the results of the tests show that the resistance to compression(RC)of the blocks in the dry state increases depending on the lime dosage and the duration of cure.At 6%lime and around 25%sand,the value of the RC of 4,966 MPa after 28 days is higher than the recommended values for load-bearing walls by the Construction Materials Center(CMC)of N’Djamena(2.4 MPa)and CRATerre(4.0 MPa).On the other hand,a 24-h stay of the dry blocks in the water causes the RC to fall from 69%to 72%depending on the lime dosage.However,the absorption coefficient of 2.23 g/cm^(2)·s^(1/2) of blocks with 6%lime is much less than 20 g/cm^(2)·s^(1/2),limit value below which the NFP554 standard qualifies the low capillarity blocks.In short,this stabilization approach makes it possible to obtain blocks resistant to aesthetic appearance,low capillarity and cost to build walls.

基于下送中回气流组织Block模型内壁面对流传热系数的讨论

以大空间缩尺模型实验室为研究对象,基于Block模型,采用2种常数法及3种温差法的表面对流传热系数取值方法,计算室内在下送中回气流组织下的空气垂直温度分布。通过与实验值的比较发现,对流传热系数温差法计算结果优于常数法。其中一种对流传热系数温差法得到的空气垂直温度与实测温度的误差最小。

Fast inter-mode decision method based on best matching block for H.264 encoding

In H.264 encoder, all possible coding modes should be checked to choose the most appropriate mode for every macroblock, which adds a heavy computation burden to the encoder. In this paper, a fast inter-mode decision method is presented to reduce computation complexity of an H.264 encoder. By detecting the best matching block （BMB） before transform and quantization, some coding modes can be skipped and the corresponding encoding steps can be omitted for these BMBs. Meanwhile this method can also be used to detect all-zero blocks. The experimental results show that this method achieves consistently significant reduction of encoding time while keeping almost the same rate-distortion performance.

A New Block-Predictor Corrector Algorithm for the Solution of y’’’=f(x, y, y’, y’’)

We consider direct solution to third order ordinary differential equations in this paper. Method of collection and interpolation of the power series approximant of single variable is considered to derive a linear multistep method (LMM) with continuous coefficient. Block method was later adopted to generate the independent solution at selected grid points. The properties of the block viz: order, zero stability and stability region are investigated. Our method was tested on third order ordinary differential equation and found to give better result when compared with existing methods.

一种阶梯块谱下的疲劳累积损伤模型

针对阶梯块谱下的材料疲劳寿命预测问题,尤其是已有相关非线性模型的计算参数依赖大量试验数据或较难选取合适的基准值,导致在实际工程中应用有一定局限性。提出了一种新的基于相邻载荷的作用系数α_(i)=(S_(i+1)/S_(i))1/b lg K,该系数中两个参数b、K来自材料疲劳寿命关系式S=KN^(-b)。结合前人的二级、三级、四级应力加载试验结果,分别计算并对比了与多种疲劳损伤模型的结果。结果表明,新模型在疲劳寿命/损伤的预测结果优于Miner模型、Manson模型、Subramanyan模型及Hashin模型,可更为准确地预测阶梯块谱下的疲劳寿命/损伤。

基于流速权重系数的阻水比计算方法

阻水比是跨河桥梁防洪评价中的一个重要参数,而现有规程中阻水比的定义仅考虑阻水面积,没有考虑流速分布对阻水程度的影响,造成当河道主槽和边滩发育时计算的断面流速分布差异性较大。根据桥梁阻水引起的局部水头损失近似与水体流速平方成正比的关系,将建桥前桥墩处水体流速与桥址处全断面水体平均流速之比的平方作为流速权重系数,用以修正桥墩阻水面积,从而改进阻水比计算公式,并应用于实例验算。计算结果表明:①位于主槽的桥墩单位阻水面积对阻水比影响较大,而位于边滩的桥墩单位阻水面积对阻水比影响较小,且流速差异越大,阻水影响程度相差越大;②当主槽流速与全断面平均流速之比达到1.17以上时,应考虑流速权重影响系数对阻水比的影响。基于流速权重系数的阻水比能够较为真实地反映流速差异带来的阻水影响,更接近工程实际阻水情况,为有效减少桥墩对防洪的不利影响,桥梁设计时应尽量采用大跨度结构一跨跨越河道主槽。

榫卯砌块结构静力与抗月震性能研究

介绍了一种采用榫卯砌块结构的月球基地设计方案,并提出了一种刚柔混合的建造方法。通过静力分析和动力时程分析研究了该结构的力学性能。在静力分析中,研究了不同榫卯形式和榫卯节点摩擦系数对结构受力的影响。在动力时程分析中,考虑了月震作用下结构的应力和位移响应。结果表明,采用斜角榫卯结构具有更大的承载能力和更小的变形,同时增加摩擦系数也可以提高结构的刚度和承载能力;采用斜角榫卯可以显著减小结构的响应,提高结构的安全性和可靠性,且随着摩擦系数的增加,结构的动力响应减小。

基于时序特征灰度图与多任务学习的综合能源负荷短期预测

准确预测综合能源系统(Integrated energy system,IES)中的电、冷、热多元负荷是提高各类能源综合效率、获得更大经济效益的关键。因此,提出一种基于时序特征灰度图与多任务学习的综合能源负荷短期预测方法。首先将初始特征集通过最大互信息系数(Maximum information coefficient,MIC)改进的快速相关滤波算法(Fast correlation-based filter,FCBF)对IES时序特征数据集进行相关性分析和冗余性分析;然后将特征选择结果利用因数重构法与MIC-gamma图像增强的方法重构为时序特征灰度图,能够直观有效地反映实际数据的特征相关性;其次采用基于多任务学习框架的(Convolutional block attention module-convolutional neural network-deep bidirectional gated recurrent unit,CBAM-CNN-DBiGRU)网络进行训练,嵌入的卷积注意力机制模块(Convolutional block attention module,CBAM)与(Deep bidirectional gated recurrent unit,DBiGRU)结构能有效加强共享层的关键信息提取和时序信息处理能力;最后以美国亚利桑那州立大学的IES数据为例对提出的方法进行测试。选取典型工作日和典型休息日并对比多种深度网络模型,测试结果表明,该模型在典型工作日的加权平均绝对百分比误差与加权均方根误差分别最大降低了0.8813%与229.2593 kW,在典型休息日则分别最大降低了0.9942%与360.8007 kW,能够有效提升IES多元负荷预测精度。

四川龙门山强震区特大泥石流综合防控技术体系研究

强震区泥石流表现出群沟暴发、范围广、持续时间长、规模大、危害重、防治难等特点,文章以强震区数十条典型特大泥石流沟为研究对象,采用野外调查、分析统计、试验验证及示范工程应用等方法,开展了典型泥石流沟特点及其防治工程效果研究,构建了强震区特大泥石流综合防控技术体系,形成了强震区特大泥石流勘查设计技术和防控关键技术体系。勘查设计体系在现有勘查技术基础上提出震裂物源识别新技术、堵塞系数分项取值新思路等;根据泥石流沟谷形态将强震区泥石流分为窄陡型和宽缓型;防控关键技术体系针对不同沟谷形态的泥石流分别进行综合防控关键技术探讨实践,统筹考虑了窄陡型和宽缓型泥石流沟上游、中游、下游沟谷特征。组合多种综合防控措施,建立了“起动控源→过程控量→末端控灾”逐级控制的强震区特大泥石流综合防控体系。结果可为强震区泥石流综合防控提供技术支撑,也可为非震区泥石流综合防控提供参考。

一种新型护面加翼块体的消浪特性试验研究

利用物理模型试验评估了一种新型人工护面块体(加翼块体)的消浪性能,分析了波浪爬高、波浪反射系数、糙渗系数和经济效益等多项指标,并与扭王字块体进行了横向对比。研究结果表明:波浪爬高随入射波高的增大而增大,波浪在加翼块体护面上的爬高要小于扭王字块体工况,加翼块体护面的斜坡堤反射系数整体上小于扭王字块体护面的斜坡堤;利用反射波高公式计算得到的加翼块体平均糙渗系数推荐值为0.383,利用波浪爬高公式计算得到加翼块体平均糙渗系数推荐值为0.456;加翼块体护面的斜坡堤与规则安装了同等重量扭王字块体的斜坡堤相比,具有更优的消浪性能(波浪反射率平均减小了18.5%、波浪爬高平均减小3.0%)和更好的经济性(造价减小18.6%)。

基于灰色关联分析法评价老气田开发潜力——以四川盆地气藏为例

老气田的储层参数差异较大,无法根据单个指标评估整个区块的开发潜力。为此,重新构建老气田开发潜力评价指标体系,从储层物性、储量规模及动用情况、生产动态、地层情况等方面对其开发潜力展开综合评价。以四川盆地气藏为例,从12个区块资料中筛选出12项相关开发评价指标,利用灰色关联分析法对这些区块的开发潜力进行综合评价及优选排序。经评价和优选,将老气田划分为Ⅰ、Ⅱ、Ⅲ、Ⅳ类潜力区块,其中开发潜力较大的Ⅰ类、Ⅱ类区块主要包括LHC、TSN、HLC、WQJ等4个区块。此评价结果可作为针对老气田潜力区块进行优选的理论依据。

半开敞筒壳网架数值风洞研究

大型筒壳网架大量运用于电厂等行业的储煤料棚中,根据工艺的需要端部会进行开洞,针对该类半开敞结构的静风效应,运用FLUENT的风工程计算功能进行数值风洞分析,基于二次开发的STADS和FLUENT的接口程序,通过菜单操作和参数控制,完成模型转换和风压的自动读取及加载,优化了程序的运行速度。以上部开敞的孟加拉某干煤棚和下部开敞的印度某钢厂筒壳网架为研究对象,考虑内外风压的共同作用,给出了不同风向角的风压系数以及风速矢量图。根据风压分布规律和风压相似分区准则,给出了上、下半开敞筒壳网架不同分区的内、外风载体型系数,其计算结果可以为该类半开敞结构的抗风设计提供参考。

灰缝厚度对蒸压加气混凝土砌块墙体热工性能的影响研究

为探究蒸压加气混凝土砌块在建筑节能方面存在的问题,利用AIRPAK软件对蒸压加气混凝土砌块墙体的热工性能进行研究。通过对300 mm厚的B04级蒸压加气混凝土砌块墙体进行不同厚度砌筑灰缝进行建模研究,探讨不同灰缝厚度情况下蒸压加气混凝土砌块墙体传热系数变化情况以及在墙体外侧粘贴分别25 mm和50 mm石墨聚苯板保温时灰缝对墙体传热系数的影响。结果表明:当砌筑灰缝厚度为8~15 mm时,墙体传热系数与不考虑灰缝时的传热系数增加比例为15.152%~31.313%,在建筑热工计算时不能忽视灰缝对墙体传热造成的影响;随着保温层厚度的增加,灰缝对传热系数的影响逐渐减小,但不可忽略;当保温层厚度为25 mm和50 mm时,传热系数增加比例分别为6.584%~15.265%和4.231%~21.154%。