Transparent niobate glass-ceramics for optical limiting

The construction of nonlinear optical materials featuring asymmetric transmission of light is of great technological importance for various applications, including optical switching and optical power limiting. A significant challenge is the scalable fabrication of material candidates with good photochemical stability, high optical transmittance, and excellent optical limiting performance. Here, we present a nanocrystallization avenue for constructing hybrid optical limiting materials that exhibit ultrafast and robust optical limiting performance. The experimental results show that the controllable relaxation of a niobate glass may lead to the clustering of Nb-O units and contracting of the bandgap. It results in the notable improvement in nonlinear optical properties, including the enhanced saturation irradiance (380 GW/cm²), doubly increased nonlinear coefficient, and decreased limiting threshold (200 GW/cm²). Our results suggest a promising material that exhibits promising applications for protecting eyes and sensitive components from laser-induced damage.     

A reanalysis method for local modification and the application in large-scale problems

A novel reanalysis method, named independent coefficients (IC) method is suggested in this study. This method is proposed to reanalyze structures with local modification which leads to a low-rank change in the stiffness matrix. IC method requires only initial solution as input, and can determine the independent coefficients for each degree of freedoms (DOFs) influenced by structural modifications. Since any extra operations such as decomposition of the initial stiffness matrix is not involved in computation procedure, the IC is a “cheap” algorithm and can be an alternative choice for reanalysis. In order to verify the performance of IC method, several large scale numerical examples are tested. The results demonstrate that the IC method has high accuracy as well as efficiency when the modification is local. The cases involving beyond 1,500,000 DOFs and 3,000,000 DOFs show that IC method has low demands on computer storage, and large scale problems can be easily reanalyzed by this method.     

SFCGDroid: android malware detection based on sensitive function call graph

International Journal of Information Security - Android is now one of the most popular operating systems in the world because of its open source character, so the threshold for hackers to make...     

亚微米级孔径微弧氧化膜层工艺研究

在其他加工参数固定的条件下,对Ld_(10)铝合金试件进行处理,然后采用扫描电镜对膜层表面显微结构进行观测分析,研究由KOH、KF、Na_2SiO_3、(NaPO_3)_6构成的溶液中各种成分浓度的变化对膜层表面放电孔径的影响.结果表明:KOH浓度变化对膜层孔径影响最小;随着Na_2SiO_3浓度的增加,膜层放电孔径先减小后快速增加;而增加KF和(NaPO_3)_6的浓度时,膜层孔径都会逐渐减小,最后趋向一个最小值.实验表明:调整好上述溶液的配比,可在试样表面获得最小放电孔径为350 nm的微弧氧化膜层.     

（Fe—Ni）—MoS2自润滑复合镀层的制备及性能研究

在酸性氯化物电解液中进行了ＭｏＳ２微粒与铁、镍共沉积的试验，确定了制备（Ｆｅ－Ｎｉ）－ＭｏＳ２复合镀层的最佳工艺参数。对所得到的复合镀层的摩擦磨损特性进行了研究。结果表明：铁镍合金镀层中弥散分布着６．４１ｗｔ％的ＭｏＳ２微粒后，与Ｆｅ－Ｎｉ合金镀层，４５＾＃淬火钢和球墨铸铁相比，其摩擦系数和损率显著降低，镀层的摩擦磨损性能得到改善。     

Multicolor Tunable Emission from Organogels Containing Tetraphenylethene,Perylenediimide, and Spiropyran Derivatives

A dendron‐substituted tetraphenylethene low molecular weight gelator (LMWG)compound, LMWG 1, is designed and investigated. Gelation‐induced fluorescence enhancement is observed for the gel based on LMWG 1 and its fluorescence can be reversibly tuned by varying the temperature of the ensemble. The photoinduced energy‐transfer can occur between LMWG 1 and PI 2 (perylene diimide) in the gel phase, but it cannot occur in the corresponding solution. The emission color of the gel of LMWG 1 and PI 2 can be tuned from cyan, yellow, to red by varying the concentration of PI 2 . By taking advantage of the photochromic transformation of spiropyran, the emission color of the organogels based on LMWG 1 and SP 3 can be switched by alternating UV and visible‐light irradiations. The emission color can also be tuned by varying the irradiation time. In this way, organogels based on LMWG 1 with multiemission color can be achieved in the presence of SP 3 after light irradiations.     

智能判断技术在变电站站用变电源系统的研究与应用

依据珠海电网系统变电站站用电源的结构变电站通信电源的特点,提出了珠海地区所有变电站站用电源系统中采用专家系统进行在线预判的方法。详细描述了站用变交流系统中在线预判断异常信息和推理机制,以及获取异常信息的方法,设计了相关的应用软件,并编制了应用软件,模拟了变电站站用变交流电源系统的事故情况。经过现场实践检验,证明该系统具有实用性,是值得推广的在线判断系统。     

杭州市民生水利发展对策研究

在分析民生水利基本内涵的基础上,介绍了杭州把发展民生水利作为建设生态城市、打造低碳城市、共建共享生活品质之城重要内容的成功经验,并针对杭州经济社会发展过程中水资源调蓄、水资源配置、水环境修复、水机制创新的薄弱环节,提出了相应的对策。     

Expedient Introduction of β‐Methoxyacrylate Unit onto 3‐Substituted Indoles and Application of the Resulting Indole‐Dienes in Organocascade toward Indolino‐Polycyclics

An efficient methodology for introducing a β‐alkoxy acrylate unit onto the indolic C‐2 position of 3‐substituted indoles has been realized by oxidative radical alkylation of indoles with a xanthate bearing dialkyl acetal functionality and subsequent elimination of alcohol by treatment with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU). The indole‐dienes thus prepared are quite stable and can be stored at room temperature for several months without obvious deterioration. Next, the indole‐dienes were successfully applied in an asymmetric cascade reaction with propargyl aldehyde catalyzed by MacMillan’s imidazolidinone and trichloroacetic acid (TCA), affording tetracyclic spiroindolines or tricyclic hydrocarbazoles in good to excellent yields with excellent ees. The practicality of this cascade was demonstrated by a gram scale preparation of a tetracyclic spiroindoline product with as low as 1 mol% catalyst loading and further elaboration of this spiroindoline compound into valuable intermediates for alkaloid synthesis.

     

广珠城际JQ450型架桥机总体设计及有限元分析

详细分析广珠城际轨道交通工程中所使用的JQ450型箱梁架桥机的总体方案,采用有限元软件ANSYS建立整机结构计算模型,以取梁工况、起重小车吊梁运行整个过程、起重小车横移到位落梁及架桥机纵移过跨等危险工况作为计算工况进行分析计算,所得计算结果与型式试验所测得的测试应力结果吻合较好,说明建立的有限元模型及载荷约束施加合理,为进一步优化同类机型提供改进方向.