一种THz频段高效光子晶体微带天线分析

对一款THz频段矩形微带贴片天线进行理论分析与设计,采用光子晶体带隙结构介质,通过对空气孔半径、孔距和微带线宽度的扫频分析,微带天线获得最佳传输性能。仿真结果显示天线的回波损耗从-19.45 dB降至-41 dB,驻波比(VSWR≤2)阻带带宽从3%增加至4.1%,最大增益天线辐射方向达到8.8 dB。仿真结果表明:光子晶体带隙结构能有效提高天线的传输效能。     

5G数据机房高密度光纤布线系统的升级改造设计与实践

本文重点介绍了适应于5G数据机房改造过程中的光纤布线系统的升级改造实践,建设固网基础设施具备高性能计算、网络架构扁平化、模块化、智能化、集中式管理、可实现交叉连接等特点,在保证高密度的同时,也确保整体布线系统的灵活性和可维护性,实现网络重构与运营重构.5G网络技术的推动以及国家"互联网+"产业需求,数据信息的传输数量和...     

湖南省公安消防部队补丁管理系统建设方案

论文以湖南省公安消防部队网络系统内部出现的安全事件为例进行分析,找出安全事件出现的根本原因在于内部网络主机存在安全漏洞,由此提出整个网络系统的补丁管理建设方案。建设方案根据现有网络状况提出在隔离网络环境下,多级、分布式补丁分发,集中管理的解决思路,保证了整个网络系统的主机安全。     

Dual band rectangular patch antenna array with defected ground structure for ITS application

A dual band inset fed rectangular patch antenna array has been proposed for intelligent transportation system (ITS) application. This paper proposes 8–element patch array antenna with defected ground structure (DGS). The simulated results of 2, 4 and 8 element patch with and without DGS are also compared. Proposed antenna gets dual band of 5.02 GHz and 5.92 GHz centre frequency with DGS. The 8–element patch array antenna with DGS is fabricated and its result is compared with simulation result. 26.5 dBi and 24.9 dBi is measured gain of the proposed antenna structure for 5.02 GHz and 5.92 GHz centre frequency respectively.     

低损耗双模微带贴片带通滤波器研究

首先提出了一种新颖、简单的带有两个切角的双模微带带通滤波器结构。该结构使用单个贴片谐振器并且没有耦合缝隙,通带两端各有一个衰减极点,可以有效减小滤波器的辐射损耗。对该滤波器结构进一步改进,又提出了一种中心频率1.8GHz相互正交槽线的新型双模微带带通滤波器结构。该滤波器在中心频率1.8GHz处,回波损耗达到31.65dB,通带内最小插损为0.01dB,3dB带宽为19.44%。研究结果表明该结构可以进一步减小辐射损耗,并且可以减小滤波器的体积,有利于小型化。     

A PLASTIC TIDE: MINING FLOATING PLASTIC WASTE THROUGH LANDSCAPE PROCESSES

The United Nations estimates that 40% of the 300 million tons of plastic produced each year are disposed of within a year. At that rate there could be more plastic than fish in the sea by 2050. Developing countries such as China, Indonesia, the Philippines, Thailand, and Vietnam contribute up to 60% of the plastics waste drifting in the world’s sea. Much of the plastic is trapped in the South China Sea for two years before drifting out to the Pacific Ocean. The plastic problem has increased as Chinese recyclers have relocated to Southeast Asia and began importing waste from all over the world. The imported plastics are cheap and clean, outcompeting the dirty plastics collected locally from the tides. The recycled plastic price dropped to unprecedented level in 2017, discouraging plastic scavenging by locals. This thesis empowers the waste pickers by designing structures that incentivize plastic recycling. The thesis proposes that the plastic tides can be mined, shredded, cleaned, dried, baked, and cooled in an efficient and holistic landscape system.     

Evaluation of adhesive properties of patches based on acrylic matrices

Adhesion is an essential property of the dermal and transdermal therapeutic systems (TS). It is influenced by the composition and the thickness of the matrix and also by the characteristics of the backing layer. Our aim was to evaluate the usefulness of the “thumb tack test,” the “tack rolling ball test,” and the “peel adhesion 180° test” in the development studies and quality control of TS. These tests were performed on two series of placebo patches in which the backing layer was made of artificial silk (series 1) and polyurethane film (series 2). The patches of both series were prepared using five different mixtures of a hydrophilic adhesive copolymer and a hydrophobic nonadhesive copolymer as matrices. Plastoid® E 35 L, a copolymer of dimethylaminoethyl methacrylate and neutral methacrylic esters, was used as the adhesive polymer. Eudragit® NE 40 D, a copolymer of ethylacrylate and methylmethacrylate, was used as the nonadhesive copolymer. In the standard procedure for the peel adhesion 180° test, used in the tape industries, the adherent is made of stainless steel. Because the latter has a high surface energy, it was not suitable for the analysis of the patches with a polyurethane backing layer. Therefore, the critical surface tension of five alternative materials (rubber, polysiloxane, polyethylene, nylon, polyvinyl chloride) was evaluated. Polyethylene was selected for the modified peel adhesion 180° test, and better results were obtained in terms of feasibility of the test and ability to discriminate between the different patches prepared.     

Microwave dielectric properties of Mg1.8R0.2Al4Si5O18 (R = Mg,Ca, Sr,Ba, Mn,Co, Ni,Cu, Zn) cordierite ceramics and their application for 5G microstrip patch antenna

In this work, the effects of divalent ions on the phase structure, microstructure, and microwave dielectric properties of Mg_1.8R_0.2Al₄Si₅O₁₈ (R = Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Zn) cordierite ceramics were investigated. Complex chemical bond theory, Raman spectrum and infrared reflectance spectrum were employed to understand the relationship among structural characteristics, vibration modes and microwave dielectric properties for alkaline earth and transitional metal divalent elements doped cordierite ceramics. The optimal microwave dielectric properties were obtained for Mg_1.8Ni_0.2Al₄Si₅O₁₈ with ε_r of 4.53, Q×f of 61,880 GHz and τ_f of -32 ppm/℃. Finally, a 5G-Sub 6GHz patch antennas with a central frequency of 4.91 GHz was successfully designed and fabricated using a Mg_1.8Ni_0.2Al₄Si₅O₁₈ substrate. The antenna exhibited excellent performance with a gain of 5.83 dBi and an efficiency of 76 %, showing promise to be employed in 5 G/6G millimeter-wave communication technology.     

The application of focal species knowledge to landscape design in agricultural lands using the ecological neighbourhood as a template

The focal species approach to nature conservation provides a method for identifying management actions required to meet the needs of the most vulnerable species in a landscape with respect to the threatening processes responsible for their decline. For each threat, a focal species is identified as the one with the most critical requirement pertaining to the threat. With multiple threats, the resulting suite of focal species can be regarded as a “focal community”, whose combined needs are used to address a range of management actions. In this paper, the critical requirements of a focal community of resident land birds are identified with respect to the threats arising from the loss, fragmentation and degradation of habitat in the central wheat-belt of Western Australia. This knowledge of their critical requirements is then used to guide a landscape design procedure for the enhancement of bird habitat in the Gabbi Quoi Quoi sub-catchment of Western Australia. The landscape design procedure is framed against the concept of the ecological neighbourhood, where the necessary size, spatial arrangement, area of influence and connectivity of existing landscape elements are used as a starting point for habitat restoration and re-vegetation.     

Urban form, biodiversity potential and ecosystem services

Using data from selected areas in five UK cities, we studied the relationships between urban form and the following measures of ecosystem performance: availability and patch characteristics of tree cover, gardens and green space; storm-water run-off; maximum temperature; carbon sequestration. Although most measures of ecosystem performance declined with increasing urban density, there was considerable variability in the relationships. This suggests that at any given density, there is substantial scope for maximising ecological performance. The social status of residents was related to measures of tree cover. Housing type was significantly associated with some types of ecosystem service provision, indicating that the type of development may be important independent of its density. These findings have implications for understanding the distribution of ecosystem services and biodiversity across urban landscapes, and the management of development aimed at meeting UK government housing density targets.