A novel planar vertical double-diffused metal-oxide-semiconductor field-effect transistor with inhomogeneous floating islands

A novel planar vertical double-diffused metal-oxide-semiconductor （VDMOS） structure with an ultra-low specific on-resistance （Ron,sp）, whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region, is proposed. The theoretical limit of its Ron,sp is deduced, the influence of structure parameters on the breakdown voltage （BV） and Ron,sp are investigated, and the optimized results with BV of 83 V and Ron,sp of 54 mΩ.mm2 are obtained. Simulations show that the inhomogeneous-floating-islands metal-oxide-semiconductor field-effect transistor （MOSFET） has a superior ＂Ron,sp/BV＂ trade-off to the conventional VDMOS （a 38% reduction of Ron,sp with the same BV） and the homogeneous-floating-islands MOSFET （a 10% reduction of Ron,sp with the same BV）. The inhomogeneous-floatingislands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET. Its reverse recovery peak current, reverse recovery time and reverse recovery charge are about 50, 80 and 40% of those of the superjunction MOSFET, respectively.

A Floating Island Treatment System for the Removal of Phosphorus from Surface Waters

The goal of this project was to design, build, and test a pilot-scale floating modular treatment system for total phosphorus （TP） removal from nutrient-impaired lakes in central Florida, USA. The treatment sys-tem consisted of biological and physical-chemical treatment modules. First, investigations of prospective biological and physical-chemical treatment processes in mesocosms and in bench-scale experiments were conducted. Thirteen different mesocosms were constructed with a variety of substrates and combi-nations of macrophytes and tested for TP and orthophosphate （PO4-^3） removal efficiencies and potential areal removal rates. Bench-scale jar tests and column tests of seven types of absorptive media in addition to three commercial resins were conducted in order to test absorptive capacity. Once isolated process testing was complete, a floating island treatment system （FITS） was designed and deployed for eight months in a lake in central Florida. Phosphorus removal efficiencies of the mesocosm systems averaged about 40%-50%, providing an average uptake of 5.0 g.m ^2.a ^1 across all mesocosms. The best-performing mesocosms were a submerged aquatic vegetation （SAV） mesocosm and an algae scrubber （AGS）, which removed 20 and 50 mg.m ^2.d ^1, respectively, for an average removal of 5.5 and 12.0 g.m ^2.a ^1 for the SAV and AGS systems, Of the absorptive media, the best performance was alum residual （AR）, which reduced PO4-^3 concentrations by about 75% after 5 min of contact time. Of the commercial resins tested, the PhosX resin was superior to the others, removing about 40% of phosphorus after 30 rain and 60% after 60min. Under baseline operation conditions during deployment, the FITS exhibited mean PO4-^3 removal efficiencies of 53%; using the 50th and 90th percentile of PO4-^3 removal during deployment, and the footprint of the FITS system, yielded efficiencies for the combined FITS system of 56% and 86%, respectively, and areal phosphorus removal rates between 8.9 and 16.5 g.m ^2.a ^1

Case Study: Hydraulic Model Experiment to Analyze the Hydraulic Features for Installing Floating Islands

The viewpoint of a river is changing as people regard the river as water-friendly space where they can enjoy and share the space beyond the simple purpose of flood control alongside the improving social level. The floating islands installation was planned featuring three islands. The river’s flow and channel stability could be changed when new structures are built in a river. Hence an analysis of the hydraulic characteristic changes should need. The hydraulic model experiment in this study sought to review the impacts of the floating islands installation on the safety of flood control and stability of river channel. This study analyzed the hydraulic features affecting the surrounding stability when installing floating islands and proposed stable floating islands layout in terms of hydraulics based on the experiment results.

生态浮床根系密度及过流流量对矩形明渠水力特性的影响

针对河道中生态浮床对水力特性的影响不明确、不利于河道行洪排涝等问题,研究了生态浮床对矩形明渠水力特性的影响。首先,基于ANSYS-fluent软件,利用多孔介质概化生态浮床,构建了含生态浮床的矩形明渠三维水动力数值模拟模型;然后,用水槽试验验证了该模型的可行性,在此基础上探索了生态浮床根系密度、过流流量对矩形明渠水流水动力特征及其变化规律的影响。结果表明,生态浮床段的流速在垂线上呈“S”型三区分布,且根系密度及过流流量的增大使流速的三区分布更显著;紊动能和雷诺应力与生态浮床根系密度和过流流量成正比,可见生态浮床根系密度和过流流量对明渠水力特性影响较大。

枸杞岛筏式贻贝养殖海域鱼类群聚特征

为探究筏式贻贝养殖生境鱼类资源养护功能,于2020年9-12月对枸杞岛筏式贻贝养殖生境(分表层区和底层区)及周边岩礁生境的鱼类进行了多网目组合刺网采样。应用相对重要性指数IRI、多样性指数并结合等级聚类、非度量多维标度排序(nMDS)分析鱼类组成和群落结构。结果显示,在2种生境中共采集鱼类55种,隶属于10目34科47属,其中贻贝养殖生境采集到37种(底层和表层分别为29和20种);岩礁生境共采集到40种。在鱼类组成上,中国花鲈和鲻是贻贝养殖生境表层区的典型优势种,而黄姑鱼和褐菖鲉是贻贝养殖生境底层区的典型优势种;褐菖鲉同时也是岩礁生境的典型优势种。多样性分析表明,贻贝养殖生境的总体鱼类多样性要高于岩礁生境,但尚不显著。多元分析显示,各月份2种生境中的鱼类群落格局均可分为3种类型,虽与养殖表层区、养殖底层区和岩礁区并非严格一致,但各群落间差异依然显著。研究表明,大规模筏式养殖设施的存在吸引了众多中上层鱼类及底层鱼类,也为岩礁生境优势鱼类提供了额外的栖息环境,发挥了近似于浮鱼礁系统的资源养护作用。研究结果可为岛礁海域海洋牧场目标种的选择和人工生境构建模式的应用提供重要参考。

原位优势菌人工浮岛耦合生态基处理炼化黑臭水体中试研究

纳污水体的整治成为炙手课题,但对东北高寒盐的纳污水体净化技术未完善。本研究以生态基为膜载体,利用其与芦苇人工浮岛、原位优势菌形成的耦合修复体系开展东北地区某炼化纳污水体净化效果研究。研究表明,当在温度25℃,溶氧浓度4 mg/L,pH值8.0,以碳素纤维草为材料作为生态基,投放密度2根/浮岛单元的环境下时,该耦合系统对纳污上覆水体COD、NH_(4)^(+)-N、TN和TP平均去除率为最佳,可达到78.40%、79.18%、84.05%和79.76%。实现了炼化纳污水体的原位净化目标,提升了上覆水污染物的去除率,为该技术在炼化纳污上覆水体原位治理工程化应用中系统构建与运行提供理论基础。

从营养平衡角度分析富营养化水体生态修复方法

调节水体营养平衡是控制富营养化水体碳、氮、磷营养负荷及恢复水体生态系统的重要手段。从微生物、水生植物和水生动物三方面剖析了基于营养平衡调控的水体生态修复机理。着重介绍了基于营养平衡调控的工程修复方法(生态浮岛,沉水植物,人工湿地,微生物修复)的原理、优缺点及改良方法。生态浮岛易受水生植物的根茎长度及系统碳源的限制,可悬浮复合填料或提供还原态无机物作为电子供体替代有机碳源;将水生动物、微生物与沉水植物结合可提高沉水植物修复法的环境适应性;人工湿地存在碳氧水平和基质碳源不足的问题,可通过增氧和向基质添加天然有机物质、无机底物等方法解决;微生物修复受到的限制因素较少。未来可在工程应用中组合使用上述修复方法,从而构建多级水生态平衡系统。

城市水环境生态修复技术研究进展

随着我国城镇化进程的不断加速发展,生活、工业污水排放量逐年增加,城市水环境问题正变得愈发突出。近几年,生态修复技术作为一种绿色环保、可持续的水处理工艺,被逐渐应用于城市水环境的修复研究。在此基础上,综述了城市水环境生态修复技术的研究进展,主要包括生物浮岛,人工湿地、稳定塘等技术,并进一步总结了城市水环境生态修复技术的工程技术要点,讨论了水生植物在生态修复中的作用;最后对城市水环境生态修复技术的经济效益进行了分析,旨在呼吁城市水环境管理中更加重视生态修复技术的应用,以实现城市水环境的可持续发展。

复合生物膜微生物修复河道水环境技术

由于人口增长和经济建设的扩大,水生态环境系统遭到严重破坏,沿河农村和工矿企业对河道水体的影响尤为严重。作为衡量水体污染程度的重要指标之一,水体中的氨氮和有机污染物对生态环境和人类身心健康造成一定影响,环境治理和水生态系统修复治理迫在眉睫。加之沿河工矿企业生产废水流入河道内,导致河道水体的污染具有多重性和复杂性。根据山西省阳泉市郊区温河治理水质提升工程为例,通过“高效生态浮岛+复合曝气生物膜修复”多方位立体式水生态净化技术和新型绿色生物膜修复技术,最终净化塘出水氨氮≤1.1mg/L,总氮≤1.3mg/L,水质指标达到地表Ⅳ类标准。运行成本0.12元/m^(3),低于同类型最新技术“底泥生物氧化技术”运行成本的3~4倍,值得应用推广。

基于浮岛的可自清洁阵列式太阳能电路研究

旨在探索基于浮岛的可自清洁阵列式太阳能电路的设计和性能。传统的太阳能电池板常常受到灰尘、污垢和污染物的影响,降低其能量转换效率。为了解决这一问题,设计了一种基于浮岛的可自清洁系统,该系统通过水泵和漂浮架底部水资源来保持太阳能电池板的清洁状态。首先,介绍了基于浮岛的可自清洁阵列式太阳能电路研究概述,阐述了其目前的研究现状,其次,讨论了基于浮岛的可自清洁阵列式太阳能电路的应用原理及设计构建,最后,设计了一种基于浮岛的可自清洁阵列式太阳能发电板组,以期有助于阵列式太阳能电力系统的质量和效率提升。

乡村旅游景观廊道湿地水体净化处理及循环再生利用研究

针对乡村旅游景观廊道湿地水体污染物去除率低的问题,研究乡村旅游景观廊道湿地水体净化处理及循环再生利用。建立回归分析模型,明确水体污染物总量。根据净化需求布置石墨烯和纳米材料,展开光催化氧化降解处理。搭建复合介质人工浮岛,模拟水体流速调整浮岛结构参数,设计混合充氧装置,净化水体。利用厌氧池、缺氧池等装置,实现水体循环再生利用。实验结果表明:所提方法净化处理6周后,水体中氨氮、硝酸盐氮、总氮、总磷去除率分别为95.6%、74.4%、88.5%和91.3%,符合廊道湿地水体治理要求。

基于生态理念的城市园林景观设计——以福建为例

基于生态理念,以福建为例,对其城市园林景观进行了设计,结果表明,在景观生态学理论指导下,提出城市公园设计对于地域性、自然性、多样性、整体性、动态性、可持续发展等各种原则都要严格遵循,所制定的园林景观空间结构优化方案是针对景观廊道、节点、印象而进行的,在与景观生态学理论结合后总结城市公园组成元素及设计方法,包括空间结构优化设计、空间形态设计、环境要素的生态设计。提出人工-自然复合系统(Artificial-Natural Complex System,ANCS)、生态浮岛法两种高效景观水处理技术,对基地内水质进行净化。

人工浮岛阻水效应试验研究

近年来,人工浮岛技术作为一种新型的绿色水处理工艺,广泛应用于河道净水技术中,但浮岛阻水的负面影响也正日益突显。依据浮岛在河道中的运用特点,通过概化物理模型试验数据,系统分析了浮岛前壅水值对人工浮岛的阻水效应,定义了阻水系数为表征阻水效应的特征值,探究了浮岛阻水效应影响因素及其影响规律。试验采用量纲分析法和正交设计试验,并结合敏感性分析,确定了人工浮岛阻水效应的主要影响因素。基于最小二乘原理,对主要影响因素与阻水系数之间的关系进行多元回归分析,得到了数学表达式。结果表明:浮岛的存在,使得其上游出现水位壅高,下游出现水位降低的现象。而阻水系数的大小与试验因素浮岛尺寸、河道水深、浮岛吃水深度、河道宽度、浮岛离岸距离有关,其中,阻水系数与弗劳德数、浮岛相对宽度(浮岛宽度与河道宽度的比值)和相对吃水深度(浮岛吃水深度与河道水深的比值)分别成幂函数正相关。

The progress in the verification of key technologies for floating structures near islands and reefs

In 2019 a Scientific Research&Demonstration Platform was deployed near islands and reefs in South China Sea by a joint research group of 7 institutes and universities in China.It is a simplified small model of a two-module semi-submersible-type VLFS.The test on site has continued for more than one and half years since then for long-term observations to validate the developed key technologies for design and behavior predictions of floating structures deployed near islands and reefs.An integrated information system was set up to continuously collect and inspect the data of the encountered waves,structure responses,connector forces,mooring line forces,anti-corrosion status of the platform,the performance efficiencies of a floating breakwater nearby and a wave energy converter attached on the breakwater.In this paper,the status of the on-site measurements and validations of the key technologies are briefly described.

有机质浮岛智能增氧系统的搭建与试验

针对有机质浮岛水面复合种养模式增氧效果的比较,设计并制造了一种有机质浮岛智能增氧系统。为探究在日常增氧需求时不同增氧方式对该模式池塘溶氧调控的影响,应用3种不同增氧方式进行增氧效果试验,结果表明:3种增氧方式均对池塘水体溶氧量有积极作用,由于浮岛固有的消浪作用导致耕水机和叶轮式增氧机扰动水体能力降低,从增氧效果来看,有机质浮岛增氧系统>叶轮式>耕水机。通过对不同增氧方式的综合对比,旨在为浮岛生产中增氧方式的合理选择提供参考。

Numerical investigation of flow with floating vegetation island

Floating vegetation island(FVI)provides an effective way to remove excessive nutrition and pollutants in rivers.The Reynolds stress model(RSM)is employed to investigate the hydrodynamic characteristics induced by varied canopy densities of FVI in an open channel.In longitudinal direction,four regions are subdivided according to the flow development process:upstream adjustment region(LUD),diverging flow region(LDF),shear layer growth region(LSD),and flilly developed region.The increasing canopy density accelerates the flow adjustment in the diverging flow region and shear layer growth region,signaling a shorter distance to reach an equilibrium stage,while LUD keeps a constant.The vertical profiles of the normalized velocity are found to be self-similar downstream of the diverging flow region.In the vertical direction,the streamwise velocity profiles in the mixing layer collapse for all densities and obey the hyperbolic tangent law.Normalized penetration depth into the canopy was fitted as a function of dimensionless canopy density given by δc/hc=0.404(CDahc)^-0.316.This finding indicates a large space for rapid water renewal between the canopy region and the underlying water driven by the shear-scale vortices.In the lateral direction,the intensification of secondary current and the increasing number of secondary current cells with increasing canopy density reveal that dense floating canopies contribute to strong momentum exchange.The centers of vortices move as canopy density increases,while the vortices in canopy region do not merge with those in the gap region,as limited by the height and width of the canopy region.The distribution of longitudinal velocity in the transects is significantly influenced by secondary current.

河道内水生植物曝气浮岛生态修复技术

植物及曝气浮岛通过以水生植物、微生物为主的食物链发挥生态净化功能,同时利用人工纤维填料等富集微生物,牡蛎壳吸附磷,多方位净化水体。以坚实的水生树木为主轴,不仅提高生态浮岛的抗风浪性能,还增加了生态浮岛的生物多样性,从而也减小了生态浮岛对季节性的依赖。新型组合生态浮岛安装有喷淋系统纳米增氧器并设有增氧曝气管,浮岛区域外安装有喷淋系统,有效增加了水体流动性和含氧量,提升了生态浮岛的深层净水能力,保证了沉水植物的采光与成活率。

生态修复技术在石山口水库水源地保护中的应用

由于农村生活污水处理率低,未处理的生活污水通过支流进入水库,对水库水源地水质存在威胁,而生态修复技术在水质提升、水源地保护方面有较好的效果。文章以石山口水库饮用水水源地为例,针对石山口水库的污染源特性,在小潢河、洗脂河两条支流的汇入口构建表流湿地,在水动力条件较差的水域布置生态浮岛、沉水植物系统,利用表流湿地、生态浮岛、沉水植物相结合的生态修复技术措施,对提升改善库区水质、区域生态环境具有良好的效果,对其他水源地保护工程具有重要的借鉴意义。

人工生物浮岛在富营养化水体治理中的应用

浮岛技术作为一种新兴的富营养化水体生态处理措施,已得到人们越来越多的重视。结合实例,回顾了浮岛技术的发展历程,介绍浮岛的种类、应用领域及技术特点,指出人工生态浮岛技术在富营养化水体治理中具有广阔的应用前景。同时对浮岛技术今后的发展方向进行了初步探讨。

人工浮岛技术及其应用

人工浮岛是一种生长有水生植物或陆生植物的漂浮结构,由于其独特的特点,能够被应用于多种类型的滨水区,且能提供重要的生态功能。人工浮岛单元易于调整空间配置形式,固定方式多样。太湖五里湖的工程实例表明:(1)人工浮岛上植物生长迅速,很快就能形成美丽的景观;(2)湖滨工程区内营养盐的浓度被大幅度消减,工程区内外透明度分别为80～120cm和40～50cm,浊度分别为15.9NTU和53.4NTU;(3)河口段浮岛边营养盐去除率为TP51.86%、TN39.64%、NH4+-N66.92%,浮岛撤除后,河口的净化效果变差,其对营养盐的去除率仅为TP18.2%、TN9.2%、NH4+-N27.8%。