Weighted residual method for diffraction of plane P-waves in a 2-D elastic half-spaceⅢ:on an almost circular arbitrary-shaped alluvial valley

Scattering and diffraction of elastic in-plane P- and SV-waves by a surface topography such as an elastic canyon at the surface of a half-space is a classical problem which has been studied by earthquake engineers and strong motion seismologists for over forty years. The case of out-of- plane SH-waves on the same elastic canyon that is semicircular in shape on the half-space surface is the first such problem that was solved by analytic closed-form solutions over forty years ago by Trifunac. The corresponding case of in-plane P- and SV- waves on the same circular canyon is a much more complicated problem because the in-plane P- and SV- scattered waves have different wave speeds and together they must have zero normal and shear stresses at the half-space surface. It is not until recently in 2014 that analytic solution for such problem is found by Lee and Liu. This paper uses their technique of defining these stress-free scattered waves, which Brandow and Lee previously used to solve the problem of the scattering and diffraction of these in-plane waves on an almost-circular surface canyon that is arbitrary in shape, to the study of the scattering and diffraction of these in-plane waves on an almost circular arbitrary-shaped alluvial valley.

Body Shape Dissatisfaction, Weight Status and Physical Activity among a Sample University Students in Saudi Arabia

The purpose of this study was to examine the prevalence of body shape dissatisfaction, weight and physical activity status among university students and predictors for body shape dissatisfaction. A cross sectional study was carried out in a sample comprising of 368 female and male university students aged 18 years or more at King Faisal University, Saudi Arabia. Body weight, height, Body Shape Questionnaire (BSQ) and physical activity level were used as assessment tools. Chi-square and independent sample T-test were used to assess gender difference. Linear regression analysis was conducted to examine predictors of the body shape dissatisfaction. Overall, 65% of students had normal BMI, more males then females overweight (23%), while more females underweight (16.8%). Females have higher body shape dissatisfaction (33.5%) then males (21.4%), half of males inactive and this percentage increased in females to (73.8%). Overweight males were more dissatisfied with their body shape (10.7%) than females (6.3%). Almost one fifth of inactive males dissatisfied comparable to quarter inactive females dissatisfied with their body shape. Younger age is predictor for body shape dissatisfaction in both genders, also weight in males. BMI and being married female was predictor for body shape dissatisfaction. Collectively results indicate that body shape dissatisfaction and inactive lifestyle were prevalent among females than male’s age, weight;BMI and marital status was the most predictor for body shape dissatisfaction. However developing educational program to promote body shape satisfaction and active lifestyle will be very useful especially among females.

基于改进粒子群算法的机械臂振动抑制研究

SCARA机械臂在工作过程中和工作终止后都会出现振动问题,为了降低机械臂的残余振动,选取粒子群作为寻最优抑振轨迹的优化算法,针对粒子群算法在轨迹寻优时收敛性差以及出现停滞现象问题,提出采用非线性递减惯性权重和粒子种群跳跃的方法对粒子群算法进行改进。利用机械臂振动抑制实验平台,使用改进的粒子群算法进行抑振轨迹优化并进行实验研究,验证结果可行且有效,得到抑振指标最小的最优抑振轨迹。

区域一体化下自贸协定保障措施对中国农业安全的影响研究

全球一体化趋势下,中国与多个国家签署了自贸协定,农产品贸易的增加在一定程度上加剧了我国农业的外部风险,探究自贸协定的保障措施条款对农业产业安全的影响有利于日后我国在拟定自贸协定时更好地考虑到对农业的保护。本文基于中国与其他20国在2005—2020年签订的协议数据,采用综合熵权法和TOPSIS法对农业产业安全进行系统测度,讨论贸易协定中保障措施的设计对中国农业产业安全的影响。研究发现:保障措施对中国农业产业安全的作用机制呈倒U型,保障措施实施程度适度对中国农业安全的保护作用最大,保障措施实施程度过高或过低对其保护都相对有限,甚至会造成不良影响。

基于最优权重和形状文法的关中民间艺术在家具设计上的应用

为了对陕西关中地区民间艺术进行归纳和梳理,本文构建了陕西关中地区民间艺术文化基因图谱,并运用现代设计方法进行转译,赋予了关中地区民间艺术活态化、多样化、年轻化的呈现。首先,通过对陕西关中地区的实地考察和相关文献资料的整理分析,深入解读和探究关中地区的民间艺术。然后,引入“文化基因”理论,从形态、色彩、材质、语义、环境、纹样六个方面剖析陕西关中民间艺术的文化因子,并结合文化创意表现,拓宽陕西关中民间艺术的表现形式和传播手段。最后,通过对文化因子的时尚化转化,并结合多元设计形式,实现了对传统关中地区民间艺术内涵的继承和创新,为陕西民间艺术装饰内涵和形态创新的传承和发展提供了新理念、新思路、新方法。

针对中心型肥胖大学生实施运动、饮食、健康教育联合干预效果的研究

目的:探讨采用运动、饮食、健康教育联合干预方法对中心型肥胖大学生身体成分与身体形态的影响效果。方法:随机抽取山西省某重点高校50名体脂检测为肥胖的大学生,并从中抽取32名中心型肥胖大学生作为研究对象,对其进行为期12周运动、饮食、健康教育联合干预,干预前后测试各项指标,并对结果进行比较和分析。结果:干预后,男大学生体重、BMI、体脂率、体脂百分比、胸围、腰围、臀围、大腿围较干预前均得到非常明显改善(P值均<0.01);女大学生体重、BMI、体脂率、体脂百分比、腰围、大腿围较干预前均得到非常明显改善(P值均<0.01),胸围、臀围较干预前均有明显改善(P值均<0.05)。结论:采用12周运动、饮食、健康教育联合干预方法,可有效改善中心型肥胖大学生肥胖现状,减脂效果显著。同时,在身体形态与身体成分方面也取得较好改善效果,其方法可作为中心型肥胖大学生科学减脂的路径予以推广。

基于FAHP-熵权TOPSIS的瑶族刺绣纹样食品模具设计应用研究

研究瑶绣纹样在现代食品模具设计中的应用,以弘扬中华优秀传统文化。综合采用多种调研方法,深入挖掘目标用户对食品模具的审美和设计需求。研究首先构建了一个双目标模糊层次分析模型(FAHP),通过目标用户访谈获取需求信息,进一步利用熵权TOPSIS对设计要素进行量化评估。为确保问题的针对性和实效性,结合专家可信度,逼近理想解排序法确定关键准则层,并与FAHP权重结果相结合,以识别出待解决的核心问题。在此基础上,构建瑶绣基因样本库,运用形状文法进行纹样推演,成功设计出15种融合瑶绣元素的食品模具方案。经过灰色关联度法的评估,最终确定最优设计方案进行相关设计实践。本研究不仅验证了FAHP-熵权TOPSIS结合形状文法在瑶绣纹样创新设计中的实用性和合理性,为瑶族文化与现代设计融合提供新思路。

Post-transcriptional regulation of grain weight and shape by the RBP-A-J-K complex in rice

RNA-binding proteins(RBPs)are components of the post-transcriptional regulatory system,but their regulatory effects on complex traits remain unknown.Using an integrated strategy involving map-based cloning,functional characterizations,and transcriptomic and population genomic analyses,we revealed that RBP-K(LOC_Os08g23120),RBP-A(LOC_Os11g41890),and RBP-J(LOC_Os10g33230)encode proteins that form an RBP-A-J-K complex that negatively regulates rice yield-related traits.Examinations of the RBP-A-J-K complex indicated RBP-K functions as a relatively non-specific RBP chaperone that enables RBP-A and RBP-J to function normally.Additionally,RBP-J most likely affects GA pathways,resulting in considerable increases in grain and panicle lengths,but decreases in grain width and thickness.In contrast,RBP-A negatively regulates the expression of genes most likely involved in auxin-regulated pathways controlling cell wall elongation and carbohydrate transport,with substantial effects on the rice grain filling process as well as grain length and weight.Evolutionarily,RBP-K is relatively ancient and highly conserved,whereas RBP-J and RBP-A are more diverse.Thus,the RBP-A-J-K complex may represent a typical functional model for many RBPs and protein complexes that function at transcriptional and post-transcriptional levels in plants and animals for increased functional consistency,efficiency,and versatility,as well as increased evolutionary potential.Our results clearly demonstrate the importance of RBP-mediated post-transcriptional regulation for the diversity of complex traits.Furthermore,rice grain yield and quality may be enhanced by introducing various complete or partial loss-of-function mutations to specific RBP genes using clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein 9 technology and by exploiting desirable natural tri-genic allelic combinations at the loci encoding the components of the RBP-A-J-K complex through marker-assisted selection.

基于多源数据融合的瑶族刺绣纹样设计应用研究

文章旨在探索瑶族刺绣纹样在现代设计中的应用,尝试利用多源数据融合的方法进行创新设计。首先,通过问卷调查、文献检索和目标用户访谈法获取用户审美需求并构建模糊层次分析模型(FAHP),利用熵权TOPSIS法对设计要素进行量化分析和筛选。其次,通过调研和资料收集构建瑶绣纹样样本库,提取基元并依据形状文法推演规则进行草图方案推演。最后,运用模糊层次分析法评估和确定最佳设计方案。结论,验证了FAHP-熵权TOPSIS融合形状文法进行瑶绣纹样创新设计的科学性与合理性,为瑶族刺绣纹样在现代设计中的应用提供了新的思路,推动瑶族刺绣文化的保护与传承。

滩羊脂尾性状表型分析

为了解脂尾绵羊的尾部性状特征,该试验选择滩羊典型生产区开展调查和试验观测,通过测量滩羊尾部尺寸、重量及尾骨特征,分析滩羊尾型特征及脂尾性状间的表型相关。结果显示:滩羊尾型可分为圆盘形尾、楔形尾和三角形尾3种;滩羊尾椎数量为17~21枚不等:根据尾椎椎骨的完整程度,滩羊的尾椎可分为4类,第1类尾椎的横突、棘突、椎弓、椎孔完整,第2类尾椎的横突完整,棘突、椎弓、椎孔退化,第3类尾椎的横突、棘突、椎弓、椎孔均发生退化,第4类尾椎椎骨之间融合,无关节囊。滩羊尾重与尾厚,尾脂率与尾重及尾脂重之间相关性显著。滩羊尾重与尾长、尾厚之间的最优回归方程为:y=-2.237+0.401 x 3+0.041 x 1(R 2=0.634,P<0.01)。

仿生蛋形箱梁力学性能研究

通过测量统计多组禽类蛋的长轴、短轴获得禽类蛋的几何特征参数,通过分析仿生蛋形截面与传统矩形截面的惯性矩设计出拥有与矩形箱梁相同截面惯性矩的仿生蛋形箱梁,同时利用有限元法分析两种箱梁的抗弯性能和抗屈曲能力,获得两种箱梁的力学性能与几何特征参数间的规律。最终,根据蛋形几何特征重新设计门式起重机主梁并分析两种主梁在危险工况中的刚度和强度。通过门式起重机主梁的应用,证明仿生蛋形箱梁拥有与传统矩形箱梁相似的结构力学性能的同时,其重量能够比传统矩形主梁轻11.11%。

含不同孔洞类岩石材料的动力响应机制研究

为揭示动载作用下深埋巷道的横截面形状效应,制备了含5种不同孔洞形状(矩形(R)、圆形(C)、直墙拱形(S)、纵、横椭圆形(E_(∥)、E_(⊥)))的水泥砂浆类岩石材料试样,利用落锤冲击试验系统地开展了试样动力响应特征研究。从应变时程曲线、洞周裂纹扩展过程、破坏模式3方面讨论了孔洞形状的影响,并结合PFC2D对试样的动态抗压强度、细观开裂机制进行了分析。结果表明:相同的冲击荷载作用下,纵椭圆试样的极限应变最大。孔洞顶板宏观裂纹的起裂位置位于中部;矩形和直墙拱形孔洞试样底板处裂纹更易从角点位置向下扩展,而其他孔洞形状的试样则从底板中部向下扩展贯通。矩形、直墙拱形和横椭圆形孔洞试样的顶板以张剪复合破坏为主,而圆形和纵椭圆形试样顶板的张拉破坏更显著。纵椭圆、直墙拱、圆形、矩形、横椭圆试样的动态抗压强度依次降低,故纵椭圆形试样的抗冲击效果最好。冲击荷载作用初期,拉应力主要集中于孔洞顶板处,集中区域大小与孔洞上边界的横向跨度正相关;试样临近峰值应力时,拉应力由顶板向两侧扩散至整个试样。峰后纵椭圆和圆形孔洞试样的回弹模量与弹性模量基本一致,塑性变形较小,而其他孔洞试样具有较高的残余应变。

贡水白柚果实分级标准研究

果实科学分级对于保证果实品质,提高鲜果附加值,促进贡水白柚产业发展是必不可少的。贡水白柚是宣恩县农业主导产业之一,本研究以随机选取的210份贡水白柚果实为材料,进行果形指标、质构、糖度及其相关性分析。结果表明,贡水白柚全果及果肉质量差异明显,全果质量为734~2 178 g,平均1 128.64 g;果肉质量440~731 g,平均564.61 g,根据全果及果肉质量可分为4级。全果质量、果肉质量及横径与果皮顶距、底距、中距、纵径、糖度等各性状指标呈明显的相关关系,可作为主要分级指标。因此,建议将贡水白柚全果质量作为主要分级指标,果实横径作为第二分级指标进行综合分级,对提高贡水白柚的经济效益意义重大。

星形多臂丁苯共聚物的分子结构设计与合成

以正丁基锂为引发剂、苯乙烯与丁二烯为单体、双四氢糠丙烷为极性结构调节剂、六氯乙硅烷为偶联剂,采用活性负离子聚合技术设计并合成了一系列具有星形结构的多臂丁苯共聚物(S-g-SSB-6)。使用凝胶渗透色谱分析了S-g-SSB-6的分子量及其分布、偶联臂数和偶联效率,使用旋转流变仪测试了S-g-SSB-6、以SiCl_(4)为偶联剂的星形多臂丁苯共聚物及线型结构丁苯共聚物(L-SSB)的流变性能,并考察了支链长度和支链柔顺性对S-g-SSB-6流变性能的影响。结果表明,S-g-SSB-6的偶联臂数达到4.1、偶联效率均大于80%;相同重均分子量下S-g-SSB-6的熔体黏度较L-SSB更低、流体流动性更好;当支化度相同时,S-g-SSB-6的熔体黏度随着单臂分子量和分子链刚性的增加而增大。

Development of a mass model in estimating weight-wise particle size distribution using digital image processing

Particle size distribution of coarse aggregates through mechanical sieving gives results in terms of cumu- lative mass percent. But digital image processing generated size distribution of particles, while being fast and accurate, is often expressed in terms of area function or number of particles. In this paper, a mass model is developed which converts the image obtained size distribution to mass-wise distribution, mak- ing it readily comparable to mechanical sieving data. The concept of weight/particle ratio is introduced for mass reconstruction from 2D images of particle aggregates. Using this mass model, the effects of several particle shape parameters （such as major axis, minor axis, and equivalent diameter） on sieve-size of the particles is studied. It is shown that the sieve-size of a particle strongly depend upon the shape param- eters, 91% of its variation being explained by major axis, minor axis, bounding box length and equivalent diameter. Furthermore, minor axis gives an overall accurate estimate of particle sieve-size, error in mean size （D-50） being just 0.4%. However, sieve-size of smaller particles （〈20 ram） strongly depends upon the length of the smaller arm of the bounding box enclosing them and sieve-sizes of larger particles （〉20 mm） are highly correlated to their equivalent diameters. Multiple linear regression analysis has been used to generate overall mass-wise particle size distribution, considering the influences of all these shape parameters on particle sieve-size. Multiple linear regression generated overall mass-wise particle size distribution shows a strong correlation with sieve generated data. The adjusted R-square value of the regression analysis is found to be 99 percent （w.r,t cumulative frequency）. The method proposed in this paper provides a time-efficient way of producing accurate （up to 99%） mass-wise PSD using digital image processing and it can be used effectively to renlace the mechanical sieving.

Scattering and diffraction of plane P-waves in a 2-D elastic half-space Ⅱ：shallow arbitrary shaped canyon

Scattering and Diffraction of elastic in-plane P-and SV-waves by a surface topography such as an elastic canyon at the surface of a half-space is a classical problem which has been studied by earthquake engineers and strong-motion seismologists for over forty years. The case of out-of-plane SH waves on the same elastic canyon that is semi-circular in shape on the half-space surface is the first such problem that was solved by analytic closed form solutions over forty years ago by Trifunac. The corresponding case of in-plane P-and SV-waves on the same circular canyon is a much more complicated problem because, the in-plane P-and SV-scattered waves have different wave speeds and together they must have zero normal and shear stresses at the half-space surface. It is not until recently in 2014 that analytic solution for such problem is found by the author in the work of Lee and Liu. This paper uses the technique of Lee and Liu of defining these stress-free scattered waves to solve the problem of the scattered and diffraction of these in-plane waves on an almost-circular surface canyon that is arbitrary in shape.

基于XGBoost-PSO的混凝土重力坝体型多目标优化设计

为解决重力坝优化设计以截面尺寸作为唯一设计变量,缺乏考虑材料属性对重力坝优化设计影响的问题,综合经济、抗震安全进行重力坝多目标优化设计方法研究,构建了综合经济、抗震安全指标的多因素评价体系;采用ABAQUS软件对重力坝进行有限元静动力分析,基于计算结果采用变权功效系数法进行量化评价;采用XGBoost-PSO算法进行寻优得到最终优化方案。实例验证结果表明:多目标优化方案与初始方案相比,在经济、抗震安全指标上都得到了明显改善;相比传统单目标优化模式,经济、安全多目标优化更适用于抗震安全要求高的重力坝工程。

Anti-plane deformations around arbitrary-shaped canyons on a wedge-shape half-space:moment method solutions

The wave propagation behavior in an elastic wedge-shaped medium with an arbitrary shaped cylindrical canyon at its vertex has been studied.Numerical computation of the wave displacement field is carried out on and near the canyon surfaces using weighted-residuals(moment method).The wave displacement fields are computed by the residual method for the cases of elliptic,circular,rounded-rectangular and flat-elliptic canyons,The analysis demonstrates that the resulting surface displacement depends,as in similar previous analyses,on several factors including,but not limited,to the angle of the wedge,the geometry of the vertex,the frequencies of the incident waves,the angles of incidence,and the material properties of the media.The analysis provides intriguing results that help to explain geophysical observations regarding the amplification of seismic energy as a function of site conditions.

用于ETC系统的扇形声表面波滤波器设计

该文设计了一款用于电子不停车收费系统(ETC)的声表面波(SAW)滤波器。该款滤波器采用3-1-3分节的电容加权结构和电极宽度控制(EWC)的换能器单元结构,基片材料为128°Y-X铌酸锂。通过对滤波器外围匹配电感、换能器反射指结构和膜厚的优化,实现了滤波器小插入损耗和高阻带抑制,制作滤波器的中心频率为40 MHz,插入损耗为-7.5 dB。该文突破常规设计方法,采用在扇形结构中换能器全抽指加权SAW滤波器的设计手段,使器件最终满足ETC项目使用要求。

高含水期油藏剩余油聚集度表征方法

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