摘要：经典克拉尼图形(Chladni patterns,CP)是特征向量的视觉表示,在振动分析、乐器设计、粒子操纵和分离等领域中具有广泛的应用.均质结构通常会表现出高度规则化的CP,这限制它们的应用场景.因此,实现面向应用来逆向设计结构的CP是非常重要的,而这可以通过使用拓扑优化来实现CP的逆向设计.本研究提出了一种使用基于密度的拓扑优化算法来设计结构CP的方法.优化列式中,给出了描述图形的指标函数,并以最小化特征向量和目标CP之间的误差构建了优化目标.数值结果表明,所提出的方法可以为指定的单阶或多阶CP生成新颖的材料分布.这表明了本文所提出的方法能够实现CP的精确定制设计,进一步为面向应用的需求提供了更多选择.

摘要：目的:建立一套系统的方法来模拟矽晶太阳能电池的翘曲行为,进而分析因翘曲而产生的残留应力。创新点:1.利用纳米压痕实验及电子显微镜测量材料性质及结构尺寸,帮助有限元分析更准确地模拟太阳能电池的翘曲行为;2.提出了2个针对不同矽晶太阳能电池因翘曲产生的简易残留应力的计算公式。方法:1.利用纳米压痕实验测量铝胶及银胶的材料性质,使用电子显微镜测量铝胶及银胶的结构尺寸;2.建立非线性有限元分析模型并与实验结果进行比较(图6),得出不同矽晶太阳能电池残留应力分布结果(图7);3.将简易残留应力公式(公式(6)和(7))和有限元分析得到的结果进行比较(图9)。结论:1.建立了一套有效模拟矽晶太阳能电池翘曲行为的分析方法,该方法包含3个部分:(1)纳米压痕实验测量铝胶和银胶的材料性质;(2)电子显微镜测量细部结构尺寸;(3)非线性有限元分析。利用此方法模拟的翘曲行为较其它计算方法更贴近实验结果。2.该方法不仅能分析不同矽晶太阳能电池的翘曲行为,而且能提供除了翘曲以外的其它信息,比如残留应力。本文提出了2个较为简易的残留应力计算公式,计算不同矽晶太阳能电池因翘曲而产生的残留应力。3.该方法考虑了银胶对矽晶太阳能电池翘曲的影响,在实际应用中可以帮助分析不同银胶的网印方式对矽晶太阳能电池翘曲的影响。本文以帮助某公司设计太阳能电池为例,证明了利用该分析方法在实际应用中帮助公司分析银胶网印的可行性。

摘要：阐述基于可靠度理论的基础设计的评估。首先总结具有结构抗力和荷载效应2个基础变量的结构可靠度基本理论。结构抗力的不确定性可以由统计学上的平均值和变异系数(cov或Ω)来描述。变异系数指变量的标准差和平均值的比值。敏感度分析的结果显示结构抗力的变异系数(Ω)R在其应用范围之内时,在分析结构可靠度方面扮演着相当重要的角色。基于这些阐述,在预先指定的风险水平(pf)上ΩR一定有其上限。当结构抗力呈正态分布的时候,这个极限ΩR独立于荷载效应随机性,和安全指数β成反比。安全指数可以定义为在标准正态分布区间极限状态到原点之间的最小距离。在这个极限ΩR之下,结构可以在预定风险水平之下安全工作。中心安全系数(FS)可以由结构抗力和荷载效应的变异系数根据平方关系求得。然而,一些情况下结构抗力为非正态分布的情况并不少见。因此,等效正态分布的概念可以用来得到非正态分布结构抗力的ΩR极限。地质方面的随机变量可能是正态分布,也可能是非正态分布,结构抗力中基本变量之间的关系可能是线性也可能是非线性,或者非常复杂以致于结构抗力只能通过有限元分析才能得到。在此情况下,随机数可以通过蒙特卡洛模拟技术获得。拟合的结构抗力的分布可以在随机试验的基础上通过配合度检验确定。现实中,土壤的力学特性不是各向同性的,同样也不能认为是单一材料的,它们的不确定性是不可以被忽略的。简便的设计方式认为不确定参数是常数,并且通过使用定值的安全系数来确定结构截面,设计原则没有将土壤参数对安全系数的影响考虑进去。参考计算出来的失效概率表明,确定值的安全系数法无法保证足够的安全。因此,在某种情况下,安全系数大于等于3,对于结构容许承受能力,并不能认为太保守。

摘要：目的:在实际工程服役过程中,纤维增强塑料(FRP)约束混凝土柱在遭遇极限荷载前往往已经经历了长时间的轴压荷载作用。因此,相比其短期力学性能,本文旨在研究FPR约束混凝土柱在长期荷载作用后的力学性能。创新点:1.考虑长期轴压荷载作用,提出一种轴压作用下圆形截面FRP约束混凝土柱的长期变形分析模型;2.提出了长期轴压作用后的FRP约束混凝土本构模型,从本构关系的角度描述两个方面的影响机理。方法:运用混凝土和FRP徐变的长期变形分析迭代计算方法(图3)。结论:1.提出的长期变形分析模型实现了对FRP约束混凝土柱任意目标时刻的应力和应变状态的高效、准确预测;2.将提出的本构模型嵌入有限元软件中,有效地实现对长期轴压作用的考虑;3.基于Open Sees有限元软件,验证了长期变形分析模型和本构模型的有效性和准确性。

摘要：Bone cancer is a critical health problem on a global scale,and the associated huge clinical and economic burdens are still *** many clinical approaches are currently used for bone cancer treatment,these methods usually affect the normal body functions and thus present significant ***,advanced materials and additive manufacturing have opened up promising avenues for the development of new strategies targeting both bone cancer treatment and post-treatment bone *** paper presents a comprehensive review of bone cancer and its current treatment methods,particularly focusing on a number of advanced strategies such as scaffolds based on advanced functional materials,drug-loaded scaffolds,and scaffolds for photothermal/magnetothermal ***,the main research challenges and future perspectives are elaborated.

摘要：由于其双层规划结构本质上的非凸性,交通网络设计问题一直以来都是交通规划领域中最为困难的问题之一。尤其在考虑混合了连续变量与离散变量的决策变量时,得到的混合网络设计形式进一步增加了问题的难度。本文引入了一种代理模型优化算法,用以解决三种不同种类的网络设计问题,包括连续、离散与混合的情形。我们证明了提出的算法在解决连续网络设计问题时,能够确保"渐进完全收敛"的性质,即在给定足够长的计算时间时,算法能够以概率1收敛到全局最优解。为了展示本文提出的框架在实际问题中的表现,我们用大量的算例对比了代理模型算法与大量用于解决网络设计问题的经典算法、启发式算法的效果。结果表明,以效率与精确度而论,代理模型算法是其中最优秀之一,同时它还能够有效地解决超过20个变量的较大规模的问题。本文提出的代理模型优化框架也能够用于解决交通领域的其他优化问题。

摘要：风屏障由于能提高侧风下列车的行车安全性,近年来引起了学者的广泛关注。然而,在过去的几十年中,风屏障结构参数(如风屏障高度和透风率等)对列车迎风面和背风面的平均压力系数差的影响研究尚不充分。为综合考虑风屏障高度、透风率以及风屏障与列车间距对列车平均压力系数差的影响,本文基于正交设计方法,对25个不同结构参数工况进行了详细数值模拟研究,并采用同步风洞试验验证了结果的正确性。研究结果表明:随着透风率(R)的增加,列车平均压力系数差先减小后增大;随着高度(H)的增加,列车平均压力系数差先增加后减少;而随着风屏障与列车间距(D)的增大,列车平均压力系数差则呈单调减小趋势。此外,根据极差与方差分析理论发现,三个因素的相对重要性为:透风率>高度>风屏障与列车间距。最后,确定了建议风屏障透风率和高度,分别为20%和110 mm。而当透风率为40%,高度为85 mm时,列车处于相对不安全的状态。研究成果可为风屏障的结构设计提供参考。

摘要：Ground motion intensity measure (IM) is an important part in performance-based seismic design. A reasonable and efficient IM can make the prediction of the structural seismic responses more accurate. Therefore, a more reasonable IM for super high-rise buildings is proposed in this paper. This IM takes into account the significant characteristic that higher-order vibration modes play important roles in the seismic response of super high-rise buildings, as well as the advantages of some existing IMs. The key parameter of the proposed IM is calibrated using a series of time-history analyses. The collapse simulations of two super high-rise buildings are used to discuss the suitability of the proposed IM and some other existing IMs. The results indicate that the proposed IM yields a smaller coefficient of variation for the critical collapse status than other existing IMs and performs well in reflecting the contribution of higher-order vibration modes to the structural response. Hence, the proposed IM is more applicable to seismic design for super high-rise buildings than other IMs.

摘要：This paper deals with the economically optimized design and sensitivity of two of the most widely used systems in geotechnical engineering: spread footing and retaining wall. Several recent advanced optimization methods have been developed, but very few of these methods have been applied to geotechnical problems. The current research develops a modified particle swarm optimization (MPSO) approach to obtain the optimum design of spread footing and retaining wall. The algorithm handles the problem-specific constraints using a penalty function approach. The optimization procedure controls all geotechnical and structural design constraints while reducing the overall cost of the structures. To verify the effectiveness and robustness of the proposed algorithm, three case studies of spread footing and retaining wall are illustrated. Comparison of the results of the present method, standard PSO, and other selected methods employed in previous studies shows the reliability and accuracy of the algorithm. Moreover, the parametric performance is investigated in order to examine the effect of relevant variables on the optimum design of the footing and the retaining structure utilizing the proposed method.

摘要：Experimental study was carried out on the in-plane bending behavior of glass plates without lateral supports, and the effects of the factors, such as height-to-span ratio, on the stability of glass panels were studied. Results show that the in-plane bending glass plates with both ends simply supported and their upper edge free lose overall stability under loads, which belongs to the limit-point type of instability. It is found that the buckling load increases linearly with the increase of height-to-span ratio of the glass plates. The lateral stress of in-plane bending glass plates without lateral supports increases linearly under loads; while the large-area stress increases nonlinearly and the lateral stress is not the controlling factor of instability. In finite element analysis, the first buckling mode is regarded as the initial imperfection and imposed on the model as 1/1000 of the span of the components. The numerical buckling load according to the theory of large deflection is less than the experiment result, which is more conservative and can provide some reference for design. For the design method, when the in-plane load is imposed on the glass plate, its lateral strength and the deflection should be verified. Considering the stability of the in-plane bending glass plate without reliable lateral support, buckling is another possible failure mode and calls for verification.