基于分布式组件动态集成的网络GIS设计模式及其实现*

摘要：提出了一种基于分布式组件动态集成方法的网络GIS开发模型。该模型允许用户定制扩展功能组件,提供扩展组件与原有系统实时、动态、无缝集成机制,并可在一个平台上提供实现C/S及B/S两种网络GIS工作模式,并提供单机模式的后台数据管理系统,满足了中小型应用系统对网络GIS平台功能小而全的需求。阐述了该开发模型的概念设计、架构设计及关键技术,并开发实现了一个原型系统FreeXGIS,验证了该模型的可行性。     

普适计算系统可用性度量

普适计算系统可用性度量具有典型的面向用户特点,为刻画用户行为需要引入具有非指数分布性质的用户状态,并且需要考虑用户态与系统态关联分析时的复杂情况。传统的连续时间马尔科夫链和半马尔科夫过程都不能很好地对以上情况给予分析。鉴于此,文章基于马尔科夫重生过程(MRGP)提出了普适计算系统的可用性度量方法。首先建立具有普适计算模式的用户模型,基于此构建了普适计算系统可用性度量的MRGP模型,对可用性进行了随机过程分析,给出了对应瞬态和稳态行为的度量方法,结合普适计算模式的特点定义了普适计算系统请求可用性度量。最后进行了数值分析,评价了普适计算系统可用性在MTTF和MTTR下的变化情况,据此导出来构建高可用普适计算系统需要考虑一些原则,并分析了用户和系统参数等因素对普适计算系统可用性度量的影响。     

多层岩盐矿爆破切割压裂工艺

多层岩盐矿（含芒硝矿）的开采，普遍采用分层建井回采工艺，即每回采一层盐，均需分别建一组回采井，回采费用高。该文介绍一种新的回采工艺－爆破切割全程裸露盐层，其特点是建一组回采井，采用爆破切割方法，将所有盐层裸露并予以回脂，大大降低回采费用，提高回采速度。     

Energy Harvesting Research: The Road from Single Source to Multisource

Energy harvesting technology may be considered an ultimate solution to replace batteries and provide a long‐term power supply for wireless sensor networks. Looking back into its research history, individual energy harvesters for the conversion of single energy sources into electricity are developed first, followed by hybrid counterparts designed for use with multiple energy sources. Very recently, the concept of a truly multisource energy harvester built from only a single piece of material as the energy conversion component is proposed. This review, from the aspect of materials and device configurations, explains in detail a wide scope to give an overview of energy harvesting research. It covers single‐source devices including solar, thermal, kinetic and other types of energy harvesters, hybrid energy harvesting configurations for both single and multiple energy sources and single material, and multisource energy harvesters. It also includes the energy conversion principles of photovoltaic, electromagnetic, piezoelectric, triboelectric, electrostatic, electrostrictive, thermoelectric, pyroelectric, magnetostrictive, and dielectric devices. This is one of the most comprehensive reviews conducted to date, focusing on the entire energy harvesting research scene and providing a guide to seeking deeper and more specific research references and resources from every corner of the scientific community.     

Multiwall Carbon Nanotubes Directly Promote Fibroblast–Myofibroblast and Epithelial–Mesenchymal Transitions through the Activation of the TGF‐β/Smad Signaling Pathway

A number of studies have demonstrated that MWCNTs induce granuloma formation and fibrotic responses in vivo, and it has been recently reported that MWCNT‐induced macrophage activation and subsequent TGF‐β secretion contribute to pulmonary fibrotic responses. However, their direct effects against alveolar type‐II epithelial cells and fibroblasts and the corresponding underlying mechanisms remain largely unaddressed. Here, MWCNTs are reported to be able to directly promote fibroblast‐to‐myofibroblast conversion and the epithelial–mesenchymal transition (EMT) through the activation of the TGF‐β/Smad signaling pathway. Both of the cell transitions may play important roles in MWCNT‐induced pulmonary fibrosis. Firstly, in‐vivo and in‐vitro data show that long MWCNTs can directly interact with fibroblasts and epithelial cells, and some of them may be uptaken into fibroblasts and epithelial cells by endocytosis. Secondly, long MWCNTs can directly activate fibroblasts and increase both the basal and TGF‐β1‐induced expression of the fibroblast‐specific protein‐1, α‐smooth muscle actin, and collagen III. Finally, MWCNTs can induce the EMT through the activation of TGF‐β/Smad2 signaling in alveolar type‐II epithelial cells, from which some fibroblasts involved in pulmonary fibrosis are thought to originate. These observations suggest that the activation of the TGF‐β/Smad2 signaling plays a critical role in the process of the fibroblast‐to‐myofibroblast transition and the EMT induced by MWCNTs.     

旋转/牵引速度比对旋转挤出聚乙烯管结构和性能的影响

采用自行研制的聚合物管旋转挤出装置,研究了旋转挤出过程中旋转/牵引速度比对聚乙烯(PE)管结构和性能的影响。扫描电镜(SEM)和热收缩实验结果表明,通过控制旋转/牵引速度比,可有效调节PE管内串晶偏离轴向的角度,降低轴向取向度,提高PE管的力学性能。当旋转/牵引速度比为0.6时,旋转挤出PE管的环向拉伸强度从常规挤出管的19.4MPa提高到33.5MPa,提高了72.7%。     

Torsion sensor based on two cascaded long period fiber gratings fabricated by CO2 laser pulse irradiation and HF etching technique respectively

A novel torsion sensor is proposed, which is composed of one long period fibre grating and one asymmetrically corrugated long period fibre grating based on the high-frequency CO₂ laser pulses technology and burning fibre coating and etching cladding technology, respectively. By combing the advantages of the two aforementioned elements, a sensitivity of 331.7 and 310.3 pm/(rad/m) towards clockwise and anticlockwise direction, respectively, is reached in the experiments.     

An investigation on the fracturing behavior of bulk metallic glass with large plasticity

A bulk metallic glass (BMG) with large plasticity was prepared and its fracturing behavior was observed at a strain rate larger than ∼ 10^− 3 s^− 1 under uniaxial compression. Even in this strain rate condition, the BMG still exhibits an excellent plastic deformability. The BMG exhibits a large elastic limitation of about 2.43% for engineering strain and 2.46% for true strain. The engineering and true plastic strains are 3.05% and 3.18%, respectively, and the maximum compressive strength is 1810 MPa. High dense shear bands appear in the outer surfaces of the failed BMG, of which the fracture surface exhibits melting and subsequently tearing-up signs with low vein height and small droplet, orientating significantly. The fracture angle is about 54°, deviating from the theoretical fracture angle by 9°. These may be related to the unique performance characteristics and the micro-structure of the BMG.     

A Composite Polymeric Carbon Nitride with In Situ Formed Isotype Heterojunctions for Highly Improved Photocatalysis under Visible Light

Introducing heterojunction is an effective way for improving the intrinsic photocatalytic activity of a graphitic carbon nitride (GCN) semiconductor. These heterostructures are mostly introduced by interfacing GCN with foreign materials that normally have entirely different physicochemical properties and show unfavorable compatibility, thus resulting in a limited improvement of the photocatalytic performance of the resultant materials. Herein, a composite polymeric carbon nitride (CPCN) that contains both melon‐based GCN and triazine‐based crystalline carbon nitride (CCN) is prepared by a simple thermal reaction between lithium chloride and GCN. Thanks to the intimate contact and good compatibility between GCN and CCN, an in situ formed heterojunction acts as a driving force for separating the photogenerated charge carriers in CPCN. As a result, CPCN exhibits a significantly improved photocatalytic performance under visible light irradiation, which is, respectively, 10.6 and 5.3 times as high as those of the GCN and CCN alone. This well designed isotype heterojunction by a coupling of CCN presents an effective avenue for developing efficient GCN photocatalysts.     

Interface and Bond Strength of Brazing Cemented Carbide K20 to Alloy Steel AISI 4140 by High-Frequency Induction

High-frequency induction brazing of cemented carbide (WC–Co, K20) and alloy steel (AISI 4140) using Cu–Zn base filler metal was carried out. The relationship between microstructure and performance of the welding joint was investigated. It was found that the filler metal exhibited excellent wettability and metallurgical bond in the welding surface. As the heating rate reduced, welding joint appeared smooth without any visible crack. In the diffusion layer, some intermetallic compounds were observed, which were produced by the reaction of diffusion atoms. The microhardness in the middle of the welding seam was 168 Hv and it increased gradually when approaching to the edge of welding seam. With brazing temperature increased or heating rate decreased, the shear strength of welding joint increased first and then decreased. The machining test clearly revealed that the cutting temperature and the flank wear increased with the cutting speed rose. The welding joint had good shear strength when the temperature was below 500°C and the shear strength decreased seriously when the temperature exceeded 500°C.