垃圾堆体沉降对填埋气体收集效能的影响

为分析填埋场上覆载荷引起的变形沉降以及垃圾自身降解作用对气体迁移特性的影响,采用多孔介质气-固耦合和生物降解理论,构建了填埋气体迁移的H-M耦合模型,通过数值模拟方法分析有无载荷作用对填埋气体储存及迁移规律的影响。结果表明:考虑载荷作用时,底部气体的压力值明显高于顶部,且底部与顶部气体压力差值的变化趋势较无载荷作用时更明显;随着填埋年限的增加,填埋场内部气体压力逐渐降低;考虑载荷作用时场内气体压力值高于不考虑载荷作用的情况,封场1a后二者气体压力差值为0.045 kPa,但10 a后压力差值达0.346 kPa;考虑载荷作用时气井收集量比不考虑载荷作用时高14.8%;载荷的作用在一定的程度上增大了抽气井影响半径的辐射范围。因此,上覆载荷引起的沉降变形对垃圾填埋气体的收集量影响显著,在设计填埋气体收集控制系统时应考虑该因素。

污水管网检测及修复技术关于提高收集效能的研究

污水管网的检测与修复成为提升其收集效能的关键,在本次研究中,本文分析了污水管网健康评估的方法后,再以提高收集效能为目标,介绍了污水管网的检测与修复技术,希望为进一步强化污水管网运营管理能力奠定基础。

高效能雨水收集和利用技术在海绵城市排水中的应用研究

城市化进程加剧城市水文环境问题,城市防洪排涝尤为突出。高效雨水收集与利用技术为环保、高效解决方案,尤其在建设“海绵城市”中备受关注。通过理论研究和现场测试,分析该技术在海绵城市雨水排放系统的应用效果。探讨工作原理,包括雨水收集、存储和利用过程,并以某城市为样板,模拟技术应用效果,涉及雨水回收率、减排效果及经济成本。该技术为城市排水提供新思路,推动可持续发展。结果表明,这种技术能显著提高雨水利用效率,减少雨水排放量,有效改善城市内涝现象,同时也产生了良好的经济效益。最后,我们还比较了不同雨水收集与利用技术的优劣,希望建立完善的海绵城市治水模式。整体上,高效能雨水收集和利用技术在海绵城市排水方面具有较高的应用价值。

迁安市污水收集与处理效能定量评估

污水收集与处理效能直接影响合流制排水体制下的水安全和水环境,是海绵城市建设中需要解析评估的重要内容.以迁安市为例,建立覆盖“污染源—管网关键节点—污水处理厂”的监测网络,基于同步水量、水质监测结果,定量解析生活污水污染物排放系数和污水处理系统收集与处理效能,并定位问题管段具体位置和主要问题.结果表明:①合流制小区COD Cr 、NH 3-N排放系数分别为43.4、13.3g/(人·d,分流制小区COD Cr 、NH 3-N排放系数略高,分别为53.1、14.5 g/(人·d).②受地下水、河水入渗的双重影响,生活污水从进入市政管网后污染物质量浓度大幅下降,保守估计下入渗率约为32.5%,合流制管网截污干管至污水处理厂地下水、河水入渗量达到了14 471 m^3/d,分流制干管至污水处理厂地下水入渗量约为19 777 m^3/d.③污水处理厂进水水质指标均远小于设计进水水质,还存在C源不足、一部分比例的污水可生化性较差的特征,进水BOD5/TN〔ρ(BOD 5)/ρ(TN)〕变化范围为0.47~4.32,平均值仅为1.68.研究显示,地下水河水入渗严重降低污水收集处理效能,建议海绵城市建设中重视对于污水收集处理效能的摸底评估,并从污水处理系统设计和管网缺陷修复上大力整改.

污水处理提质增效综合评估体系构建与应用

目前城镇污水处理提质增效工作主要通过进厂BOD5浓度和生活污水集中收集率等单项指标进行考核评价。基于进厂BOD5浓度、污供比、雨晴比、高危河流四项指标,构建了片区层面的污水处理提质增效综合评估体系,并在深圳市进行了具体应用。实践表明,该综合评估体系可以较客观、公正的反映污水收集效能,同时也能在一定程度上指导问题的发现与整改。评估结果不仅可以支撑相关的考核工作,也可以为下一步工作指明方向。

梅州城区污水处理提质增效工作实践与思考

近年来,梅州城区污水处理提质增效结合城市黑臭水体治理,大力开展污水收集处理设施补短板,通过污水厂网建设、排水设施摸查、渗漏闸门检修、管网运行水位调控、供水漏控管理、管渠清疏改造等举措,污水集中收集率与进厂BOD5浓度都有显著提升,污水系统收集效能整体提高。基于梅州城区污水处理提质增效工作实践进行思考与总结。

大湾区某城市污水处理系统“挤外水、提浓度”提质增效策略研究

近年来,我国污水处理建设规模扩大,处理水量也逐年增加,但污水处理厂进水浓度呈逐年降低的趋势。据统计,广东省2018年523座污水处理厂约88%的进水BOD浓度未达到100 mg/L,与城市污水处理厂进水浓度提质增效的达标要求仍有较大的差距。文章基于大湾区某城市污水处理系统的水质检测成果判断需优先推进沿河排水口整改、雨污错混接改造、工业废水排水管理等工作,提出了相应的整改措施,工程实施后可有效缓解管道运行水位高、污水收集效能低的问题。

Energy Efficiency Optimization in Relay-Assisted Networks with Energy Harvesting Relay Constraints

In this paper we consider data transmission in a decode-and-forward(DF)relay-assisted network in which the relay is energy harvesting(EH) powered while the base station(BS) is power-grid powered.Our purpose is to maximize the BS's energy efficiency(EE) while making full use of the relay's renewable energy and satisfying the specific average throughput requirements.In contrast to existing literature on energy harvesting system which only considers the radio transmission power,we take the static circuit power into account as well.We formulate the EE optimization problem and prove that the EE of the BS and relay are both quasiconvex in the instantaneous transmission rate.Then we divide the complex optimization problem into two point-to-point link level optimization parts and propose an energyefficient resource allocation(EERA) scheme in which power control and sleep mode management are jointly used.The simulation results demonstrate that EERA may achieve good energy saving effects.We also compare the EE of an energy harvesting relay system with a power-grid powered one and provide more insight into the EE problem of energy harvesting relay system.

Energy-Efficient Mobile Data Collection Adopting Node Cooperation in an Underwater Acoustic Sensor Network

This paper considers an underwater acoustic sensor network with one mobile surface node to collect data from multiple underwater nodes,where the mobile destination requests retransmission from each underwater node individually employing traditional automatic-repeat-request(ARQ) protocol.We propose a practical node cooperation(NC) protocol to enhance the collection efficiency,utilizing the fact that underwater nodes can overhear the transmission of others.To reduce the source level of underwater nodes,the underwater data collection area is divided into several sub-zones,and in each sub-zone,the mobile surface node adopting the NC protocol could switch adaptively between selective relay cooperation(SRC) and dynamic network coded cooperation(DNC) .The difference of SRC and DNC lies in whether or not the selected relay node combines the local data and the data overheard from undecoded node(s) to form network coded packets in the retransmission phase.The NC protocol could also be applied across the sub-zones due to the wiretap property.In addition,we investigate the effects of different mobile collection paths,collection area division and cooperative zone design for energy saving.The numerical results showthat the proposed NC protocol can effectively save energy compared with the traditional ARQ scheme.

Study on Absorption and Regeneration Performance of Novel Hybrid Solutions for CO_2 Capture

Recently, a kind of hybrid solution MEA-methanol shows a better CO_2 capture performance over aqueous MEA solution. However, the vaporization of methanol is the biggest disadvantage that hinders its application, so it is necessary to minimize the vaporization of methanol during both the absorption and regeneration processes. In this work, two kinds of hybrid solutions were studied and compared with aqueous MEA solution and MEA-methanol solution, including MEA/TEA/methanol solution and MEA/glycerol/methanol solution. The absorption property of MEA/glycerol/methanol solution is better than aqueous MEA solution within a certain period of time and the absorption property of MEA/TEA/methanol solution is too poor to be used in CO_2 capture. By increasing the concentration of TEA and decreasing the concentration of MEA, the absorption rate, CO_2 capture efficiency and absorption capacity all decreased. Upon adding glycerol, the cyclic capacity decreased and the generation temperature increased, and moreover, the density and viscosity also increased considerably. So after adding TEA and glycerol, the CO_2 capture performance of MEAmethanol solvent cannot be improved.

Energy Efficient Resource Allocation in Timesharing Multiuser Systems with Hybrid Energy Harvesting Transmitter

An energy effi cient resource allocation scheme in timesharing multiuser system with a hybrid energy harvesting transmitter is studied in this paper. Specially, the operation energy of system is supplied by constant energy and energy harvesting, which harvests energy from external environment. Our goal is to maximize the energy effi ciency of timesharing multiuser systems by considering jointly allocation of transmission time and power control in an off-line manner. The original nonconvex objective function is transformed into convex optimization problem via the fractional programming approach. Then, we solve the convex problem by Lagrange dual decomposition method. Simulation results show that the proposed energy efficient resource allocation scheme has a better performance than the scheme which decomposes optimization problem into two parts(power allocation, time allocation) to solve iteratively.

The analysis of X-ray response of CdZnTe detectors

CdZnTe is an excellent material candidate for high efficiency,high-resolution room-temperature nuclear radiation detectors,and the CdZnTe detectors are being widely used in medicine,industry,safeguard and scientific X-ray and γ-ray imaging and spectroscopic applications.In this work,three CdZnTe planar detectors with different grades,named CZT-1,CZT-2 and CZT-3,respectively,were fabricated.And the effects of mobility,lifetime and de-trapping time on the performance of CdZnTe planar detector,such as the energy resolution,charge collection efficiency and peak to valley ratio,were analyzed.The charge collection efficiency depends on the product of carrier mobility and lifetime,which has a great effect on the energy resolution of detector when the efficiency is less than 90%.The de-trapping time of carriers in deep levels should be responsible for the peak to valley ratio and "polarization".

Metal/nanocarbon layer current collectors enhanced energy efficiency in lithium-sulfur batteries

Lithium-sulfur （Li-S） batteries with intrinsic merits in high theoretical energy density are the most promising candidate as the next-generation power sources. The strategy to achieve a high utilization of active materials with high energy efficiency is strongly requested for practical applications with less energy loss during repeated cycling. In this contribution, a metal/nanocarbon layer current collector is proposed to enhance the redox reactions of polysulfides in a working Li-S cell. Such a concept is demon- strated by coating graphene-carbon nanotube hybrids （GNHs） on routine aluminum （AI） foil current collectors. The interracial conductivity and adhesion between the current collector and active material are significantly enhanced. Such novel cell configuration with metal/nanocarbon layer current collectors affords abundant Li ions for rapid redox reactions with small overpotential. Consequently, the Li-S cells with nanostructured current collectors exhibit an initial discharge capacity of 1,113 mAh g-1 at 0.5 C, which is -300 mAh g-1 higher than those without a GNH coating layer. The capacity retention is 73% for cells with GNH after 300 cycles. A reduced voltage hysteresis and a high energy efficiency of ca. 90% are therefore achieved. Moreover, the AI/GNH layer current collectors are easily implanted into current cell assembly process for energy storage devices based on complex multi-electron redox reactions （e.g., Li-S batteries, Li-O2 batteries, fuel cells, and flow batteries）.