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基于视情维修的航空发动机备发预测方法研究 被引量:8
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作者 陈凤腾 左洪福 +1 位作者 李惠娟 倪现存 《机械科学与技术》 CSCD 北大核心 2008年第8期1081-1084,1088,共5页
鉴于发动机的备发和性能退化以及维修方式的相关性,本文引入维修度概念,同时应用广义更新过程(GRP)对比例危险模型(PHM)进行了改进,建立反映寿命、性能参数、环境等参数变化趋势以及维修方式的备发模型。最后,以某航空公司CF6型发动机... 鉴于发动机的备发和性能退化以及维修方式的相关性,本文引入维修度概念,同时应用广义更新过程(GRP)对比例危险模型(PHM)进行了改进,建立反映寿命、性能参数、环境等参数变化趋势以及维修方式的备发模型。最后,以某航空公司CF6型发动机为例进行计算和比较。备发量对在翼发动机数比率为9.02%的结果满足经验估算结果。这表明应用本方法进行备发量决策方法切实可行,具有较大的应用价值。 展开更多
关键词 航空动机 比例危险模型 广义更新过程 维修度 备发
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发动机机队备发仿真研究 被引量:2
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作者 赵洪利 张猛 《计算机应用与软件》 北大核心 2021年第1期87-92,142,共7页
合理的备发数量,对于航空公司的正常运营有着重要意义。考虑性能衰退、硬件损伤和偶然性损伤三种发动机下发因素,在先进先出排队规则下考虑了MRO维修能力,采用离散系统仿真的方法建立备发仿真模型,分阶段为机队制定15年的备发规划。仿... 合理的备发数量,对于航空公司的正常运营有着重要意义。考虑性能衰退、硬件损伤和偶然性损伤三种发动机下发因素,在先进先出排队规则下考虑了MRO维修能力,采用离散系统仿真的方法建立备发仿真模型,分阶段为机队制定15年的备发规划。仿真结果与航空公司现行备发率基本一致。该模型对航空公司备发规划的制定具有一定的参考价值。 展开更多
关键词 仿真 备发 保障率
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基于离散事件仿真的航空发动机备发规划
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作者 赵洪利 段朝鹏 《计算机仿真》 北大核心 2020年第2期97-101,共5页
针对利用传统的数学解析法在解决航空发动机备发数时建模复杂且计算困难的问题,提出了一种基于离散事件仿真的解决方法。首先,通过对历史下发数据进行分析,统计出发动机机队因性能衰退和硬件损伤下发的时间,并拟合出合适的时间分布;然后... 针对利用传统的数学解析法在解决航空发动机备发数时建模复杂且计算困难的问题,提出了一种基于离散事件仿真的解决方法。首先,通过对历史下发数据进行分析,统计出发动机机队因性能衰退和硬件损伤下发的时间,并拟合出合适的时间分布;然后,以性能衰退和硬件损伤下发的时间分布为输入条件,结合机队机龄情况,建立航空发动机备发数仿真模型;最后,在满足保障率为97%的情况下,以3年为一规划期,求解出未来15年里不同阶段机队的最优备发数。结果表明,该仿真方法为解决发动机机队备发规划提供了一个合理的决策方案。 展开更多
关键词 离散事件 仿真 性能衰退 硬件损伤 备发
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利用统计技术确定航空公司备发数量 被引量:2
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作者 韦昀 《民航科技》 2003年第4期48-49,52,共3页
关键词 统计技术 航空公司 备发数量 备发 机务工作
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民用航空发动机维修计划启发式算法 被引量:5
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作者 付旭云 钟诗胜 《计算机集成制造系统》 EI CSCD 北大核心 2010年第7期1552-1557,共6页
为制定合理的航空发动机维修计划,在分析送修时间和备发选择的影响因素的基础上,建立了航空发动机维修计划多目标组合优化模型。为描述备发对发位的适合程度,提出了备发软约束适合度的概念和计算方法。考虑到模型的复杂性,提出了一种基... 为制定合理的航空发动机维修计划,在分析送修时间和备发选择的影响因素的基础上,建立了航空发动机维修计划多目标组合优化模型。为描述备发对发位的适合程度,提出了备发软约束适合度的概念和计算方法。考虑到模型的复杂性,提出了一种基于逐步构解策略的启发式算法进行模型的求解,并对算法的时间复杂度进行了分析。在此基础上,提出了航空发动机维修计划方案集的构造方法和选择方法。采用某航空公司的实际数据对所提算法进行了验证,并开发了一个原型系统,结果表明了该算法的有效性。 展开更多
关键词 航空动机 维修 多目标组合优化 式算法 备发选择
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基于视情维修的涡轴发动机维修保障辅助决策体系研究 被引量:3
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作者 李俊杰 王尧 +2 位作者 张强 胡民民 闫旭东 《计算机测量与控制》 2021年第6期205-211,共7页
复杂装备科学的维修保障策略是保证装备合理使用与适时修理的基础,是有效实施复杂装备全寿命保障的前提,关系着装备任务效能的有效发挥;文中立足于航空装备的视情维修策略,以直升机中广泛采用的涡轴发动机为研究对象,首先基于装备维保... 复杂装备科学的维修保障策略是保证装备合理使用与适时修理的基础,是有效实施复杂装备全寿命保障的前提,关系着装备任务效能的有效发挥;文中立足于航空装备的视情维修策略,以直升机中广泛采用的涡轴发动机为研究对象,首先基于装备维保过程的大量信息提出了构建涡轴发动机涡轴发动机及其关键部件寿命与健康管理综合知识库的方法、策略;其后结合涡轴发动机循环寿命统计法与基于K均值聚类算法等各类使用条件下的寿命损耗研究方法,阐明了涡轴发动机不同应用条件下的备件量化分析策略;更进一步地,以涡轴发动机关键部件典型故障模式梳理与成因分析(FMECA)与考虑故障概率的发动机核心备件的量化分析为基础,给出了涡轴发动机关键部件备件量化方法与策略;最后基于上述方法的研究成果,阐述了涡轴发动机维修保障辅助决策软件平台的体系架构;文中的相关研究成果可被用于航空发动机等复杂装备系统的维修保障策略构建与工程化应用。 展开更多
关键词 涡轴动机 视情维修 维修保障策略 备发
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配电变压器及配电线路设备防雷保护综述 被引量:1
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作者 奚全胜 《科技资讯》 2006年第5期39-40,共2页
雷电对电力设备有很大的危害性,配电网防雷的目的是使线路的雷害跳闸次数减少到最低限度、配电线路设备损害几率最小、停电范围最小,根据这一要求,概述了配电变压器及配电线路设备的防雷保护。
关键词 配电 变压器 线路 防雷
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浅议发动机备件的需求预测 被引量:1
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作者 张金柱 《航空维修与工程》 2017年第3期64-65,共2页
根据发动机送修计划和备发需求,分析了影响备发的各种因素,对发动机未来需求数量进行精细化预测,为发动机管理规划提供指导。
关键词 寿命件 适航指令/服务通告 性能 送修 备发 送修周期
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Manufacturing Development Emphases on Power Generation and Transmission Apparatus in 11th Five-Year Plan Period and Prospect to the Year 2020 被引量:1
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作者 陆燕荪 《Electricity》 2004年第1期12-16,共5页
Based on predictions on Chinese power development in the coming 20 years, this paper introduces the emphases and key technologies in power sources and power network construction, and puts for ward the major tasks and ... Based on predictions on Chinese power development in the coming 20 years, this paper introduces the emphases and key technologies in power sources and power network construction, and puts for ward the major tasks and technological orientation for machinery manufacturers to supply qualified equipment to China power industry. 展开更多
关键词 electricity generation power transmission technology power equipment MANUFACTURING
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采用OCDMA技术的全光网
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作者 马龙 李玉权 蒲涛 《飞通光电子技术》 2002年第1期57-60,共4页
提出了在未来全光网中采用OCDMA技术的实现方案。OCDMA可以和WDMA相结合,细化光交叉连接的颗粒,增强光通道层的灵活性,而且可以直接从现有网络升级;OCDMA还可以和OTDMA相结合,实现信令的全光处理和的帧定界,从而使OTDMA网无需复杂的同步... 提出了在未来全光网中采用OCDMA技术的实现方案。OCDMA可以和WDMA相结合,细化光交叉连接的颗粒,增强光通道层的灵活性,而且可以直接从现有网络升级;OCDMA还可以和OTDMA相结合,实现信令的全光处理和的帧定界,从而使OTDMA网无需复杂的同步,这将为光包交换的实现提供一种有效的手段。进一步的研究需要对全光网节点内的交换网络结构和路由协议进行深入考虑。 展开更多
关键词 全光网 OCDMA 光交叉连接 0TDMA 光电混合网 网络升级 交换 0ADM设
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Optimal Decoupling Control Method and Its Application to a Ball Mill Coal-pulverizing System 被引量:3
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作者 Yue Fu Chengwen Hong Jingyi Li 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2018年第6期1035-1043,共9页
Abstract-The conventional optimal tracking control method cannot realize decoupling control of linear systems with a strong coupling property. To solve this problem, in this paper, an optimal decoupling control method... Abstract-The conventional optimal tracking control method cannot realize decoupling control of linear systems with a strong coupling property. To solve this problem, in this paper, an optimal decoupling control method is proposed, which can simultaneousiy provide optimal performance. The optimal decoupling controller is composed of an inner-loop decoupling controller and an outer-loop optimal tracking controller. First, by introducing one virtual control variable, the original differential equation on state is converted to a generalized system on output. Then, by introducing the other virtual control variable, and viewing the coupling terms as the measurable disturbances, the generalized system is open-loop decoupled. Finally, for the decoupled system, the optimal tracking control method is used. It is proved that the decoupling control is optimal for a certain performance index. Simulations on a ball mill coal-pulverizing system are conducted. The results show the effectiveness and superiority of the proposed method as compared with the conventional optimal quadratic tracking (LQT) control method. 展开更多
关键词 Ball mill coal-pulverizing system linear system optimal decoupling control optimal quadratic tracking (LQT)control.
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Incidence of pocket hematoma after electrophysiological device placement:dual antiplatelet therapy versus low-molecular-weight heparin regimen 被引量:3
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作者 Yan CHEN Yun-Tao LI +8 位作者 Ming-Dong GAO Ze-Chun ZENG Jin-Rong ZHANG Hong-Liang CONG Yin LIU Ru ZHAO Le-Feng WANG Xin-Cun YANG Kang MENG 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2014年第3期200-205,共6页
Background Given the increasing number of patients who require dual antiplatelet (DAP) therapy and electrophysiological device (EPD) placement, perioperative antiplatelet management is a current challenge. In this... Background Given the increasing number of patients who require dual antiplatelet (DAP) therapy and electrophysiological device (EPD) placement, perioperative antiplatelet management is a current challenge. In this study, we investigated the incidence of pocket hema-toma formation after EPD placement in patients undergoing DAP therapy or an alternative low-molecular-weight heparin (LMWH) regimen. Methods This clinical observational study was performed from July 2010 to July 2012. In total, 171 patients were enrolled in the analysis after meeting the inclusion criteria. These patients were divided into two groups: 86 patients were treated with DAP therapy at the time of device implantation, and the DAP therapy was discontinued for 5 to 7 days and replaced with enoxaparin before device implantation in the other 85 patients. Adenosine phosphate (ADP)-mediated platelet aggregation and arachidonic acid-induced platelet aggregation were tested preoperatively. We compared the incidence of pocket hematoma between the two groups and the association of pocket hematoma develop-ment with ADP-mediated platelet aggregation and arachidonic acid-induced platelet aggregation.Results The incidence of pocket hema-toma in the patients who continued DAP was lower than that in the patients who replaced the dual antiplatelet regimen with LMWH (3.49%vs. 16.47%, respectively;X2 = 6.66,P 〈 0.01). Among the patients who continued DAP therapies, the rate of ADP-mediated platelet aggre-gation inhibition in patients with pocket hematomas was higher than that in patients without pocket hematomas. None of the patients under-going DAP or enoxaparin therapy developed pocket infection, thromboembolic events, or other serious complications. Multiple logistic re-gression analysis revealed that LMWH therapy was an independent risk factor for the development of pocket hematoma (RR = 0.054, 95%CI = 0.012-0.251). Furthermore, patients undergoing LMWH therapy were 5.1-fold more likely to develop pocket hematomas than were DAP-treated individuals.Conclusion Continuance of DAP therapy does not increase the risk of pocket hematoma formation after EPD placement. 展开更多
关键词 Antiplatelet drug Hematoma Low-molecular-weight heparin Electrophysiological device
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Transcatheter aortic valve implantation: a revolution in the therapy of elderly and high-risk patients with severe aortic stenosis 被引量:3
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作者 Teoman Kilic Irem Yilmaz 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2017年第3期204-217,共14页
Transcatheter aortic valve implantation (TAV1) represents a real revolution in the field of interventional cardiology for the treatment of elderly or high-risk surgical patients with severe symptomatic aortic valve ... Transcatheter aortic valve implantation (TAV1) represents a real revolution in the field of interventional cardiology for the treatment of elderly or high-risk surgical patients with severe symptomatic aortic valve stenosis. Today, TAVI seems to play a key and a reliable role in the treatment of intermediate and maybe low-risk patients with severe aortic stenosis. TAVI has also evolved from a complex and hazardous procedure into an effective and safe therapy by the development of new generation devices. This article aims to review the background and future of TAVI, elinieal trials and registries with old and new generation TAVI devices and to focus on some open issues related to post-procedural outcomes. 展开更多
关键词 High risk patients The elderly Transcatheter aortic valve implantation
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Reviews and Expectations on the Maiden Voyage of a Chinese Merchant Ship in the Arctic Northeast Route 被引量:2
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作者 Liu Jia-zhao Liu Xiao-pei Zhanu Xiao 《Journal of Shipping and Ocean Engineering》 2016年第5期302-311,共10页
This paper introduces the preparatory work and conducts an integrated review on the maiden voyage of a Chinese commercial ship on the Arctic Northeast Route. It puts forth expectations on the exploitation and utilizat... This paper introduces the preparatory work and conducts an integrated review on the maiden voyage of a Chinese commercial ship on the Arctic Northeast Route. It puts forth expectations on the exploitation and utilization of the Arctic Northeast Route in the aspects of safety, fastness, low costs, low consumption of energy and less pollution, knowledge of maritime law and navigation practice, building seaworthiness ships and making studies on the methods of sailing and maneuvering for navigation in polar waters, training qualified seafarers with navigation experiences in ice waters and establishing a safeguard system for the navigation in this route through the analysis on the weather, temperature, ice condition, route and hydrology encountered in the practice of a Chinese merchant ship in its maiden voyage in the route, and studies on the ice pilotage, convoy by icebreaker, practical condition of communication and navigation equipment in sea areas of high latitude and the economic benefit of the navigation in the Arctic Northeast Route. 展开更多
关键词 The Arctic Northeast Route Northern Sea Route NSR Navigation in Polar Area.
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Transcatheter aortic valve replacement and stroke: a comprehensive review 被引量:7
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作者 Periklis A Davlouros Virginia C Mplani +2 位作者 Ioanna Koniari Grigorios Tsigkas George Hahalis 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2018年第1期95-104,共10页
Transcatheter aortic valve implantation (TAVR) has emerged as an alternative, rapidly evolving treatment option for patients with se- vere aortic stenosis and high surgical risk. Stroke is a devastating complication... Transcatheter aortic valve implantation (TAVR) has emerged as an alternative, rapidly evolving treatment option for patients with se- vere aortic stenosis and high surgical risk. Stroke is a devastating complication being confined mainly in the periprocedural and 30-day pe- riod following TAVR, with a lower and relatively constant frequency thereafter. Early stroke is mainly due to debris embolization during the procedure, whereas later events are associated with patient specific factors. Despite the fact that the rate of clinical stroke has been constantly decreasing compared to initial TAVR experience, modern neuro-imaging with MRI suggests that new ischemic lesions post-TAVR are almost universal. The impact of the latter is largely unknown. However, they seem to correlate with a reduction in neurocognitive function. Because TAVR is set to expand its indication to lower surgical-risk patients, stroke prophylaxis during and after TAVR becomes of paramount importance. Based on clinical and pathophysiological evidence, three lines of research are actively employed towards this direction: improvement in valve and delivery system technology with an aim to reduce manipulations and contact with the calcified aortic arch and native valve, antithrombotic therapy, and embolic protection devices. Careful patient selection, design of the procedure, and tailored antithrombotic strategies respecting the bleeding risks of this fragile population constitute the main defense against stroke following TAVR. 展开更多
关键词 Aortic stenosis STROKE Transcatheter aortic valve replacement
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Sensing for advancing mining automation capability:A review of underground automation technology development 被引量:39
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作者 Ralston Jonathon Reid David +1 位作者 Hargrave Chad Hainsworth David 《International Journal of Mining Science and Technology》 SCIE EI 2014年第3期305-310,共6页
This paper highlights the role of automation technologies for improving the safety, productivity, and environmental sustainability of underground coal mining processes. This is accomplished by reviewing the impact tha... This paper highlights the role of automation technologies for improving the safety, productivity, and environmental sustainability of underground coal mining processes. This is accomplished by reviewing the impact that the introduction of automation technology has made through the longwall shearer automation research program of Longwall Automation Steering Committee(LASC). This result has been achieved through close integration of sensing, processing, and control technologies into the longwall mining process. Key to the success of the automation solution has been the development of new sensing methods to accurately measure the location of longwall equipment and the spatial configuration of coal seam geology. The relevance of system interoperability and open communications standards for facilitating effective automation is also discussed. Importantly, the insights gained through the longwall automation development process are now leading to new technology transfer activity to benefit other underground mining processes. 展开更多
关键词 Mining automation Longwal mining Longwal Automation Steering Committee Interoperability Inertial navigation Coal seam sensing
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Preparation of diamond/Cu microchannel heat sink by chemical vapor deposition 被引量:2
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作者 刘学璋 罗浩 +1 位作者 苏栩 余志明 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期835-841,共7页
A Ti interlayer with thickness about 300 nm was sputtered on Cu microchannels, followed by an ultrasonic seeding with nanodiamond powders. Adherent diamond film with crystalline grains close to thermal equilibrium sha... A Ti interlayer with thickness about 300 nm was sputtered on Cu microchannels, followed by an ultrasonic seeding with nanodiamond powders. Adherent diamond film with crystalline grains close to thermal equilibrium shape was tightly deposited by hot-filament chemical vapor deposition(HF-CVD). The nucleation and growth of diamond were investigated with micro-Raman spectroscope and field emission scanning electron microscope(FE-SEM) with energy dispersive X-ray detector(EDX). Results show that the nucleation density is found to be up to 1010 cm-2. The enhancement of the nucleation kinetics can be attributed to the nanometer rough Ti interlayer surface. An improved absorption of nanodiamond particles is found, which act as starting points for the diamond nucleation during HF-CVD process. Furthermore, finite element simulation was conducted to understand the thermal management properties of prepared diamond/Cu microchannel heat sink. 展开更多
关键词 chemical vapor deposition microchannel nanoseeding Ti interlayer Cu substrate
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Transceiver Optimization for Multi-Antenna Device-to-Device Communications 被引量:1
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作者 Daohua Zhu Yajuan Guo +4 位作者 Lei Wei Chaoyang Zhu Biyao Huang Wei Xu Chunming Zhao 《China Communications》 SCIE CSCD 2016年第5期110-121,共12页
It has been shown that the deployment of device-to-device(D2D) communication in cellular systems can provide better support for local services. However, improper design of the hybrid system may cause severe interferen... It has been shown that the deployment of device-to-device(D2D) communication in cellular systems can provide better support for local services. However, improper design of the hybrid system may cause severe interference between cellular and D2D links. In this paper, we consider transceiver design for the system employing multiple antennas to mitigate the interference. The precoder and decoder matrices are optimized in terms of sum mean squared error(MSE) and capacity, respectively. For the MSE minimization problem, we present an alternative transceiver optimization algorithm. While for the non-convex capacity maximization problem, we decompose the primal problem into a sequence of standard convex quadratic programs for efficient optimization. The evaluation of our proposed algorithms for performance enhancement of the entire D2D integrated cellular system is carried out through simulations. 展开更多
关键词 device-to-device communication interference mitigation joint transceiver design multiple antennas
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Preparation of N, O-carboxymethyl Chitosan Composite Nanofiltration Membrane and Its Rejection Performance for the Fermentation Effluent from a Wine Factory 被引量:3
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作者 苗晶 李玲玲 +2 位作者 陈国华 高从堦 董声雄 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2008年第2期209-213,共5页
N, O-carboxymethyl chitosan (NOCC) composite nanofiltration (NF) membranes were prepared by coating and cross-linking. The fermentation effluent from a wine factory was treated with the resulting NOCC/polysulfone ... N, O-carboxymethyl chitosan (NOCC) composite nanofiltration (NF) membranes were prepared by coating and cross-linking. The fermentation effluent from a wine factory was treated with the resulting NOCC/polysulfone (PSF) composite NF membranes. The permeate flux and the removal efficiencies of the resulting NF membranes for the color, chemical oxygen demand (CODcr), total organic carbon (TOC), and conductivity of the fermentation effluent were investigated in relation to the driving pressure, the feed flow, and the operation time. The permeate flux and the removal efficiencies were found to increase with the increase of the driving pressure or the feed flow. At 0.40 MPa and ambient temperature the removal efficiencies were 95.5%, 70.7%, 72.6%, and 31.6% for color, CODcr, TOC, and conductivity, respectively. The membrane was found to be stable over a 10-h ooeration for the fermentation effluent treatment. 展开更多
关键词 N O-carboxymethyl chitosan composite nanofiltration membranes fermentation effluent removal efficiencies
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A novel portable transmitter with 8 dBm output power for wireless communication equipments
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作者 张艳征 Mao Luhong +3 位作者 Zhou Xiaoqiu Zhang Shilin Deng Jianbao Xie Sheng 《High Technology Letters》 EI CAS 2014年第1期103-109,共7页
In this paper,a portable 2.42 GHz transmitter for wireless communication systems,with 8dBm output power and small size is proposed.Several novel features exist in this transmitter.First,power consumption and output ar... In this paper,a portable 2.42 GHz transmitter for wireless communication systems,with 8dBm output power and small size is proposed.Several novel features exist in this transmitter.First,power consumption and output are balanced by introducing a differential oscillator with input signal controlled biasing,which acts as both a carrier generator and an OOK modulator.Then,power consumption of the transmitter is reduced by the OOK modulated signal via switching the oscillator and the power amplifier at the same time.Furthermore,the area size is also reduced by a class-AB power amplifier,which uses the PCB antenna as the resonance inductance.With these features,the total chip area is reduced to 670μm×740μm(In a 0.18μm CMOS process). 展开更多
关键词 TRANSMITTER OOK modulator power amplifier CMOS 2.42GHz
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