某大型繁忙机场跑道大修工程设计分析

以虹桥机场东跑道大修工程为例,阐述了大修方案提出的技术依据和基础条件,介绍了方案设计中应重点考虑的关键因素,论证了所拟方案的技术合理性,最终形成完整的大修技术方案,为类似工程方案设计提供了参考。     

Automated feature validation for creating/editing feature-based component data models

In a feature-based design system, it is necessary to check if a feature is valid (i.e. dimensions and class are proper) before adding it to the component model, and to detect if there will be any changes in the existing features which interact with it. The same applies to an existing feature to be modified and its interacting features when editing a feature model. This ensures a precise feature model of component design for the downstream applications. It is a commendable goal to automate the process of feature validation, which in turn increases the system's capability and intelligence, thus reducing the requirement on the designer's effort. This paper presents a Boolean operation-based systematic methodology of automating feature validation by checking feature dimensions and class, respectively. It briefly introduces a feature-based component data model (FBCDM) suitable for process planning and NC programming, and then discusses in detail the problem of feature validation and the algorithms of feature validation for creating/editing FBCDMs.     

Design and synthesis of soluble dibenzosuberane-substituted fullerene derivatives for bulk-heterojunction polymer solar cells

Two new dibenzosuberane-substituted fullerene derivatives, dibenzosuberane-C₆₀ mono-adduct (DBSCMA) and bis-adduct (DBSCBA) were synthesized using a classical cyclopropanation reaction via a tosylhydrazone route for application as acceptor materials in polymer solar cells (PSCs). DBSCBA shows good solubility in common organic solvents and both derivatives were characterized by ¹HNMR, ¹³C NMR, MALD-TOF, elemental analysis and UV–vis absorption measurements. The shift of fullerene energy levels induced by the dibenzosuberane substitution was investigated by using theoretical simulations and ultraviolet photoelectron spectroscopy. Bulk-heterojunction PSCs based on poly (3-hexylthiophene) (P3HT) and dibenzosuberane-C₆₀ derivatives were fabricated and optimized by adjusting the donor/acceptor ratio and using thermal annealing and solvent additive. The morphologies of the active layers processed under different conditions were also examined by atomic force microscopy. When tested under an illumination of AM 1.5 G at 100 mW/cm², the highest power conversion efficiency of the devices using DBSCBA is 3.70% which is superior to that of conventional P3HT:PCBM devices.     

Size Control and Characterization of Sn-Ag-Cu Lead-Free Nanosolders by a Chemical Reduction Process

Sn-3.0Ag-0.5Cu nanosolders were synthesized via a chemical reduction method. Polyvinyl pyrrolidone (PVP) and sodium borohydride (NaBH₄) were employed as surfactant and reducing agent, respectively. Ultraviolet–visible (UV–visible) absorption and x-ray diffraction patterns revealed that alloying had successfully taken place during the reduction process. Different amounts of PVP and NaBH₄ additions influenced the nanosolder particle size. Under varying reaction temperatures and pH values, various ranges of nanosolder size were obtained. Optimized nanosolders were studied by differential scanning calorimetry to investigate the depression of the melting temperature, and were analyzed by transmission electron microscopy to measure actual particle sizes. The dependence of the particle size on the melting temperature was observed. The melting point was depressed to 204.4°C when the average diameter of the nanosolders was 20 nm. Although SnO₂ was formed on the nanosolders, it could be cleaned by citric acid. These low-melting-temperature Sn-Ag-Cu nanosolders are candidates for use in lead-free interconnect applications.     

水平井光纤视像检测技术研究

简要介绍了井下视像检测系统结构及配套工艺,通过室内试验及现场应用,证实其在井筒套管损坏分析的准确性,突出其在提升修井效率上的重要性,分析了影响检测效果的不利因素并提出应对措施。     

地铁深基坑开挖的施工仿真分析

本文运用ABAQUS软件对武汉地铁2号线小龟山车站基坑开挖分别进行了二维和三维模拟计算。计算得到二维模拟条件下围护结构内力、变形和土体位移的变化趋势与三维相近,但相应数值均大于三维的情况,充分说明了基坑具有明显的空间效应。     

J4不锈钢热轧板冷轧横裂原因分析

分析发现了J4不锈钢热轧板冷轧横裂形成的主要原因是:钢中有大量显微气泡破坏基体的连续性,降低材料的塑性,导致裂纹形成。加大脱氧、脱气力度,可减少显微气泡,预防裂纹形成。     

Experimental analysis of wet mill load based on vibration signals of laboratory-scale ball mill shell

Real-time measurement of the mill load is the key to improve the production capacity and energy efficiency for the grinding process. In this paper, experimental analysis of the wet mill load based on the vibration signals of the laboratory-scale ball mill shell is presented. A series of experiments are conducted to investigate the vibration characteristics corresponding to different grinding conditions such as dry grinding, wet grinding and water grinding. The power spectral density of the vibration signals is systematically interpreted.Experimental results show that the rheological properties of the pulp affect the amplitude and frequency of the vibration signal. The most important conclusion is that the frequency range of the shell vibration of the laboratory wet mill can be divided into three parts, namely natural frequency band, main impact frequency band and secondary impact frequency band. Finally, soft-sensor models between vibration signal and mill operating parameters of mill load are established using genetic algorithm-partial least square (GA-PLS) technology. After more work on industry scale ball mill is done, the soft-sensor modeling based on the mill shell vibration for operating parameters of mill load will improve the performance of the ball mill in the grinding process.