基于人工智能的混凝土配合比优化设计

采用遗传算法对混凝土进行配合比优化设计,以经济成本为目标函数、以人工神经网络混凝土性能预测模型为约束条件,用实数编码表示个体的染色体位串,通过选择、交叉、变异等遗传算子作用,完成遗传操作,以优胜劣汰为原则,最终达到最优解。将优化结果和工程实例的配合比进行对比,可见该方法可降低造价、节约能源,具有较好的工程使用价值。     

Self-desiccation mechanism of high-performance concrete

Investigations on the effects of W/C ratio and silica fume on the autogenous shrinkage and internal relativehumidity of high performance concrete (HPC), and analysis of the self-desiccation mechanisms of HPC showed that the autogenous shrinkage and internal relative humidity of HPC increases and decreases with the reduction of W/C respectively; and that these phenomena were amplified by the addition of silica fume. Theoretical analyses indicated that the reduction of RH in HPC was not due to shortage of water, but due to the fact that the evaporable water in HPC was not evaporated freely.The reduction of internal relative humidity or the so-called self-desiccation of HPC was chiefly caused by the increase in mole concentration of soluble ions in HPC and the reduction of pore size or the increase in the fraction of micro-pore water in the total evaporable water (Tr/Tte ratio).     

Self-desiccation mechanism of high-performance concrete

Investigations on the effects of W/C ratio and silica fume on the autogenous shrinkage and internal relative humidity of high performance concrete (HPC), and analysis of the self-desiccation mechanisms of HPC showed that the autogenous shrinkage and internal relative humidity of HPC increases and decreases with the reduction of W/C respectively; and that these phenomena were amplified by the addition of silica fume. Theoretical analyses indicated that the reduction of RH in HPC was not due to shortage of water, but due to the fact that the evaporable water in HPC was not evaporated freely. The reduction of internal relative humidity or the so-called self-desiccation of HPC was chiefly caused by the increase in mole concentration of soluble ions in HPC and the reduction of pore size or the increase in the fraction of micro-pore water in the total evaporable water (Tr/Tte ratio).     

Message design for mobile learning: Learning theories,human cognition and design principles

The demands of an increasingly knowledge‐based society and the dramatic advances in mobile phone technology are combining to spur the growth of mobile learning (mLearning). However, for mLearning to attain its full potential, it is essential to develop pedagogy and instructional design tailored to the needs of this new learning environment. At present, there is a lack of research on message design for mLearning. Towards these ends, this paper explores the principles and processes of message design for mLearning, including the influence of learning and cognitive theories, human–computer interaction principles, devices and methodologies. And it presents a number of practical guidelines for designing instructional messages for mLearning.     

利用等色干涉原理测量薄膜厚度

文章讨论了等色干涉的原理,并利用该原理给出测量介质厚度的方法.     

Teachers' private theories and their design of technology-based learning

This study explores the private theories of four vocational education teachers in Singapore who have engaged in the design of technology‐based learning for their own classes. The understanding of teachers’ private theories is important in the context of contemporary educational reforms, which emphasise the shift towards student‐centred practices and technology integration. As teachers learn to change strategies and utilise technology, they might also need to transform aspects of their private theories that could impede effective technology integration and lead them to continue with outdated educational practice. This study aims to understand and explicate areas of private theories that impede the effective design of student‐centred technology‐based learning. The final outcome of the study was a set of propositions for readers to examine for the possible application in their own environments.     

Sulphate attack resistance of high-performance concrete under compressive loading

In this paper, an experimental study on the sulphate attack resistance of high-performance concrete (HPC) with two different water-to-binder ratios (w/b) under compressive loading is presented. The sulphate concentration, compressive strength, and the mass change in the HPC specimens were determined for immersion in a Na₂SO₄ solution over different durations under external compressive loading by self-regulating loading equipment. The effects of the compressive stress, the w/b ratio, and the Na₂SO₄ solution concentration on the HPC sulphate attack resistance under compressive loading were analysed. The results showed that the HPC sulphate attack resistance under compressive loading was closely related to the stress level, the w/b ratio, and the Na₂SO₄ solution concentration. Applying a 0.3 stress ratio for the compressive loading or reducing the w/b ratio clearly improved the HPC sulphate attack resistance, whereas applying a 0.6 stress ratio for the compressive loading or exposing the HPC to a more concentrated Na₂SO₄ solution accelerated the sulphate attack and HPC deterioration.     

钢筋混凝土抗拔灌注桩的抗裂设计

通过对不同直径的抗拔灌注桩在不同抗拔荷载、不同裂缝控制等级下的抗裂设计及其纵筋用钢量与造价的对比分析,说明桩纵筋采用普通非预应力钢筋时,因受裂缝宽度的限制,其纵筋拉应力水平明显偏低,桩承受的抗拔力越大,纵筋的应力越小,相比普通钢筋混凝土桩,采用预应力螺纹钢筋的抗拔桩不仅可显著减少用钢量,当抗拔力较高时,还可节省约40%~50%的纵筋造价;同时进一步探讨抗拔桩预应力筋的配置及有效预应力的控制方法。     

商业银行ATM机混凝土机房改造设计

自动存取款机混凝土机房一般在原有商业银行营业网点内改造而成.因其具有较大集中荷载,同时由于防盗防抢的要求需新增墙体作为维护结构,墙体线荷载也比较大,因此有必要对新增荷载进行分析,进而对楼板、次梁、框架梁进行内力分析、结构验算并进行结构加固.     

影视动画中的角色造型设计

本文从动画角色在动画片中的重要性谈起,对动画角色的艺术特性进行阐述。接着列举了不同国家的数部动画作品,逐一解读,进一步体现动画角色在动画作品中对剧情构建和情节发展的重要作用。最后通过客观对比我国动画角色造型设计与其它动画产业发达国家存在的差距,提出了动画角色造型设计的创作建议。     

基于三维微焦点CT图像对高性能混凝土内部缺陷的测量和分析(英文)

为了揭示粉煤灰和磨细矿渣对混凝土微观结构初始缺陷的影响规律,采用高分辨率X-射线微焦点CT(X-ray Micro-CT)图像对具有不同胶凝材料的4个系列高性能混凝土进行了研究.混凝土微观结构和缺陷过滤之后的高分辨率三维图像均由Micro-CT配套的图像软件进行了重建.基于二维和三维图像分析得到了混凝土内部缺陷的尺寸分布和体积分数,并与常温饱水法的试验结果进行了对比.研究结果显示:矿物掺和料作为胶凝材料加入混凝土之后,由于其颗粒填充效应和火山灰效应,显著改变了硬化混凝土的微观结构特征以及初始缺陷的尺寸和空间分布特征;在水胶比和集料尺寸分布保持不变的条件下,矿物掺和料的掺入与否,是引起高性能混凝土展示出不同力学特性的主要原因.     

基于超声波测量油膜厚度方法的研究

润滑通常是保证机器正常运转的重要条件,测量润滑油膜厚度可以准确评价机械润滑效果,因此具有重要的实际应用价值.试验使用柱形油膜测厚机构与楔形油膜测厚机构,通过超声波探头发射并接收一定带宽频率的超声波信号.基于超声波谐振模型与弹簧模型,对测得的不同油膜厚度对应超声波反射信号进行快速傅里叶变换处理,通过所得反射系数求得油膜的...     

预应力混凝土结构的耐久性设计方法研究

根据预应力混凝土结构的耐久性特点,分别定义了结构构件在碳化环境和氯离子侵蚀环境下的耐久性极限状态,建立了以可靠性数学和随机过程为理论基础的数学模型,并对耐久性失效概率进行了理论分析.提出了碳化环境下的预应力混凝土结构构件的耐久性实用设计方法.计算结果表明:预应力混凝土结构的耐久性优于传统钢筋混凝土结构;现行国家规范(GB 50010-2002)中规定的混凝土保护层厚度是不足的;根据碳化和氯离子侵蚀环境的不同,混凝土保护层厚度应该分别不小于35mm和45mm.     

Assessments of tear meniscus height,tear film thickness,and corneal epithelial thickness after deep anterior lamellar keratoplasty

Objective

To assess the lower tear meniscus height (LTMH), central tear film thickness (CTFT), and central corneal epithelial thickness (CCET) after deep anterior lamellar keratoplasty (DALK).

Methods

This was a retrospective cross-sectional study of 20 patients who had DALK in one eye over a three-month period. LTMH, CTFT, and CCET of the operated eyes and the unoperated fellow eyes were measured using high-definition optical coherence tomography (HD-OCT). Correlations between three OCT assessments and age, time following surgery, graft size, bed size, and the number of residual sutures were analyzed.

Results

Compared to patients with keratoconus, patients with other corneal conditions had significantly higher CCET in the fellow eye (P=0.024). For all patients, CCET in the operated eye was significantly negatively correlated with the number of residual sutures (R=?0.579, P=0.008), and was significantly positively correlated with time following surgery (R=0.636, P=0.003). In the fellow eye, a significant positive correlation was found between age and CCET (R=0.551, P=0.012), and a significant negative correlation between age and CTFT (R=?0.491, P=0.028). LTMH was found to be significantly correlated between operated and fellow eyes (R=0.554, P=0.011). There was no significant correlation between LTMH and age, bed/graft size, time following surgery, or residual sutures (all possible correlations, P>0.05).

Conclusions

Patients with keratoconus tend to have a thinner central corneal epithelium. Corneal epithelium keeps regenerating over time after DALK. DALK did not induce a significant change in tear volume compared with the fellow eye. Postoperative tear function might depend on an individual’s general condition, rather than on age, gender, bed/graft size, time following surgery, or residual sutures.

     

中国和欧洲混凝土桥梁耐久性设计规范比较

对中国混凝土结构耐久性设计规范( GB/T 50476-2008)和Eurocode中有关混凝土桥梁耐久性设计的相关条款进行了对比.对2种规范中关于结构所处环境等级的划分和混凝土最小保护层厚度和最低强度等级等相关规定做了比较和分析.并用数值计算方法对处于碳化和氯盐侵蚀环境(海洋环境和除冰盐环境)下的桥梁耐久性设计年限进...     

以粒子蜂群网络建立高性能混凝土坍落度模型

以粒子蜂群算法(particle bee algorithm, PBA)结合神经网络(artificial neural network, NN),发展出一套能预测高性能混凝土(high performance concrete, HPC)坍落度模型的方法。以演化运算树(genetic operation tree, GOT)及倒传递网络(back propagation network, BPN)2种已发表的方法来比较其准确度。从模型的准确度可知,粒子蜂群网络(particle bee neural network, PBNN)模型预测的准确度高于GOT,但接近BPN的准确度;从参数的影响性可知,PBNN显示水、强塑剂、粗骨材、细骨材、粉煤灰及水泥添加量对于HPC坍落度的影响性大,而高炉矿渣粉用量对HPC坍落度并不敏感,显示各项材料对于坍落度的影响仍具备高度复杂性。     

从美学视觉谈个别包装与整体包装的统一

文章从当代社会大众的“品牌消费”这一带有浓厚的美学特征的消费倾向出发,对商品包装的一般美学原则进行分析,指出我国当前的包装设计存在一些缺陷和不足,认为现代包装在注重单个商品包装设计的开发时,更要重视从整体性要求出发,将单个商品包装设计的开发融入到更为宏观的包装设计链条之中,将其与本企业的其他商品、企业标识、企业理念等要素统一起来。只有如此,单个商品包装才能为产品的品牌塑造发挥作用,实现其经济价值和审美价值。     

影视动漫设计中对于绘画手法的运用

长时间的国家交往互动过程中,一些动漫作品中蕴含的中国元素与中国文化逐渐体现。影视动漫作品所采用的绘画手段是建立在创作人员坚实的创作基础之上的,通过创作人员对绘画手法的利用展现出更加生动的作品内容,这就需要打开文化门襟,实现不同文化交流。对影视动漫设计中对于绘画手法的运用进行分析,可以深刻了解现代影视动漫制作的实质与内涵。     

混凝土结构设计耐久性环境区划标准

混凝土结构耐久性环境区划标准的目的就是为混凝土结构耐久性设计提供合理的设计参数.混凝土结构耐久性环境区划标准在结构全寿命周期成本原理基础上考虑了环境对结构的影响,并将结构的重要性、结构形式和功能等多方面因素一并纳入考虑之中.首先给出了混凝土结构设计耐久性环境区划标准的概念和建立该标准的3个基本原则,其次根据自然环境条件和结构重要性等确定了区划的主要影响因素,然后以浙江省公路桥梁结构耐久性环境区划图的编制为例说明了混凝土结构耐久性环境区划的可行性与实用性,最后根据区划图给出了耐久性区划标准的若干设计规定.     

论老年产品包装

人口的老龄化,推动了老年产品的消费,也促进了老年产品包装业的发展。通过对老年消费需求和产品包装的特点分析,提出了老年产品包装的发展方向。