Design and calibration of a laminar soil box suitable for a low-capacity shake table using free-field tests on Ganga sand

The present study concentrates on design, commissioning and calibration of a uniaxial laminar soil box suitable for use on a low base-shear capacity shake table available at IIT Kanpur, India. The box is designed to simulate the behavior of soil deposits subjected to earthquake motions, with minimal boundary effects due to reflection of waves at the boundary. The 1.1 m × 1.6 m × 0.765 m box is comprised of a series of individual lamina supported independently on multiple roller bearings guided through a guide channel. The outer frame connected to the guide rods is designed in such as way that it can transfer the self weight of each lamina out of the shake table. A series of free-field tests are carried out on dry Ganga sand sample to calibrate the box. Dynamic response parameters, such as acceleration, displacement, stress-strain behavior, strain-dependant modulus and damping ratio of the sand at various depth are investigated. Large strain and subsequent increased inelasticity is observed towards the top of the sand bed. The experimental results are further compared with equivalent-linear SHAKE analysis and nonlinear finite element ground response analysis of the free-field soil using OpenSees for assessing the performance of the laminar box.     

外墙保温系统中粘结材料的检测技术分析

选择了几份典型的外墙外保温系统标准,通过对这几份标准中胶粘剂和抹面胶浆的成型和检测方法的比较,分析了现有检测技术的优劣,并结合工作实践提出了建议。     

配电线路绝缘包裹机器人研制

在介绍国内外输电线路现有机器人研究基础上，针对配电线路绝缘修复领域短板，开发了一套能够在线修复配电线路绝缘皮损伤的包裹机器人。首先，对绝缘包裹机器人的机械结构进行了设计研究，包括行走装置、升降装置和柔性输送与包裹装置；然后，开发了相应的控制系统，包括无线通讯、视觉系统等，并对其进行了抗干扰试验和耐压试验，试验结果合格；最后，通过现场绝缘包裹测试完成了机器人的功能性与可靠性验证。本项目所研发的机器人突破了在线修复、柔性包裹等技术瓶颈，解决了人工修复带来的一系列问题。样机通过现场带电包裹试验，绝缘包裹效果符合行业标准要求，达到了预期效果。     

铸造式和焊接式主轴箱体的动态特性对比分析

利用有限元法和试验模态法对立式加工中心的铸造式和焊接式两种结构的主轴箱体进行了模态分析,分别获得了其前六阶固有频率和振型。通过对比两种方法获得的结果,验证了有限元分析模型的有效性。研究表明,两种主轴箱体的阻尼比接近,但焊接式主轴箱体的各阶固有频率均要高于铸造式主轴箱体的各阶固有频率。并且铸造式主轴箱体的固有频率更接近于机床主轴的常用工作频率,焊接式主轴箱体的则远离此频率。因此对于常用主轴转速而言,焊接式主轴箱体的动态性能要优于铸造式主轴箱体的动态性能。     

Effect of functionally graded structure design on durability and thermal insulation capacity of plasma-sprayed thick thermal barrier coating

This paper aimed to design and optimize the structure of a thick thermal barrier coating by adding graded layers to achieve a balance between high thermal insulation capacity and durability. To this end, conventional TBC, conventional TTBC, and functionally graded TTBCs were deposited on the superalloy substrate by air plasma spraying. To determine the quality of the bond strength of the coatings, the bonding strength was measured. The durability of coatings was evaluated by isothermal oxidation and thermal shock tests. Then, at a temperature of 1000 °C, the thermal insulation capacity of the coatings was carried out. The microstructure of the coatings was characterized by a scanning electron microscope. The results showed that the thickness of the TGO layer formed on the bond coat in the conventional TBC and TTBC under the oxidation test at 1000 °C after 150 h was 2.79 and 2.11 μm, respectively, whereas, in the functionally graded TTBC samples, no continuous TGO layer was observed as a result of internal oxidation. The functionally graded TTBC presented higher durability than conventional TTBC due to improved bonding strength, thermal shock resistance, and the lack of a TGO layer at the bond/top coat interface. Also, the thermal insulation capacity of the functionally graded TTBC (with 1000 μm thickness of YSZ coating) was better than TTBC.     

铠装硅酸钾胶黏剂在特殊工况下的绝缘失效分析

为探索铠装硅酸盐胶黏剂在特殊环境下的绝缘特性，本文制备不同碱金属离子含量及固液配比的硅酸钾胶黏剂样品，将其固封于不锈钢管体中，在潮湿环境与高温条件下分析其绝缘性能并进行失效分析。结果表明：在潮湿环境中，胶体中的固液配比及碱金属（K⁺）含量会影响铠装试样的整体绝缘性能，当固液配比为2∶1时，硅酸钾与硅溶胶质量比在（2～1）∶1之间时，其绝缘效果较佳；在高温条件下，随着温度的升高及保温时间的延长，铠装壳体中部分合金元素渗入胶体表面，造成样品绝缘性能较大幅度的下降。     

Self-assembly of ultralight and compressible inorganic sponges with hierarchical porosity by electrospinning

The construction of three dimensional macroporous architectures holds exciting implications for applications such as catalysis, sensing, tissue engineering and thermal insulation. Here, we report a general self-assembly process for inorganic sponges with hierarchical porosity of intrafibre micro-/meso-/macropores and interfibre macropores. The as-fabricated SiO₂-TiO₂ sponge possesses a high porosity of >99.86%, ultralow bulk density of 2.9 mg cm⁻³ and enhanced compressibility (recovery from 50% compression). The self-assembly mechanism of the SiO₂-TiO₂ sponge has been investigated in detail. The results confirmed that the hydrolysis and polycondensation of mixed inorganic alkoxides could affect the solidification process and the charge transpote during electrospinning, and plays an essential role on the hierarchical porosity and the self-assembly of the sponge macro-structure. The concerted effects of the solidification and electrostatic repulsion between fibres are responsible for the self-assembly process of the electrospun PVP-SiO₂-TiO₂ sponge. When used as a thermal insulation material, the SiO₂-TiO₂ sponge shows good fireproof performances. The current contribution may guide more construction of functional inorganic macroporous architectures for advance applications in future.     

SiO2气凝胶隔热保温涂料研究及保温结构优化设计

石油化工行业是国家节能减排重点工程之一，如果相关设备设施保温不当，不仅会造成严重的热量散失，还会对油水分离和输送等产生影响。本文系统介绍了传统的以中空玻璃微珠或陶瓷微珠为主要隔热功能填料的隔热保温涂料的保温机理、性能及其存在的问题；以 SiO₂气凝胶为主要功能填料的新型隔热保温涂料研究现状及研究中的技术难点；针对不同应用环境，开发兼具防腐、防开裂、隔热保温功能的复合保温结构设计。本文为研制新型耐高温、高效水性无机隔热保温涂料的研究提供了参考方向，为隔热保温涂料在石油化工领域的工程应用提供分析。     

Sample re-weighting hyper box classifier for multi-class data classification

In this work, we propose two novel classifiers for multi-class classification problems using mathematical programming optimisation techniques. A hyper box-based classifier (Xu & Papageorgiou, 2009) that iteratively constructs hyper boxes to enclose samples of different classes has been adopted. We firstly propose a new solution procedure that updates the sample weights during each iteration, which tweaks the model to favour those difficult samples in the next iteration and therefore achieves a better final solution. Through a number of real world data classification problems, we demonstrate that the proposed refined classifier results in consistently good classification performance, outperforming the original hyper box classifier and a number of other state-of-the-art classifiers.Furthermore, we introduce a simple data space partition method to reduce the computational cost of the proposed sample re-weighting hyper box classifier. The partition method partitions the original dataset into two disjoint regions, followed by training sample re-weighting hyper box classifier for each region respectively. Through some real world datasets, we demonstrate the data space partition method considerably reduces the computational cost while maintaining the level of prediction accuracies.     

旋挖钻机设备油液智能分析与健康监测

为了对直升机盒段件入水载荷进行分析，开展了模型垂直入水冲击试验，同时采用有限元-光滑粒子流体动力学（finite element method-smooth particle hydrodynamics，简称FEM-SPH）耦合数值方法进行仿真分析，计算了不同材料构型和速度下的过载、压力及应变结果。与试验结果进行对比表明，仿真结果与试验值吻合较好，预测的结构失效破坏模式与试验结果基本一致，可为真实直升机入水冲击的结构设计提供参考。