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地下停车场无线通信保障浅析
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作者 李琪 樊悦顺 《广东通信技术》 2024年第8期56-59,共4页
地下停车场受全封闭结构的影响,移动网络覆盖通常较差,用户投诉较多,但受整体用户较少、业务量较低影响,运营商投入收益较差,亟需低成本覆盖。针对地停特点和业务需求充分分析,详细阐述覆盖地下停车场的各种手段,并给出差异化的解决方案。
关键词 地停 低成本 简易覆盖 天线
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Study on Purification Efficiency of Vertical Flow Wetlands on Domestic Wastewater 被引量:7
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作者 仝昭昭 王延华 顾中铸 《Agricultural Science & Technology》 CAS 2011年第3期461-465,共5页
The combination method of intermittent influent and vertical flow wetlands (VFW) was used in the test to treat the domestic wastewater. Four artificial wetlands including Typha latifolia wetland,Phragmites australis... The combination method of intermittent influent and vertical flow wetlands (VFW) was used in the test to treat the domestic wastewater. Four artificial wetlands including Typha latifolia wetland,Phragmites australis (P.H.) wetland,polyculture wetlands (Typha latifolia and Phragmites australis) and non-vegetation wetland were established in the test. The effects of hydraulic retention time (HRT) and plant species on pollutants removal efficiencies were studied. The results showed that when HRT=7,the treatment efficiencies of wetlands with plants for the removal of TN and NH+4-N were up to 99.65% and 99.58%,respectively. For the control wetland,TN removal efficiency was up to 87.9% when HRT were 6 days,and NH+4-N removal efficiency was up to 91.8% when HRT were 5 days. TP removal efficiencies of four wetlands were higher than 93% when HRT was 6 days. Through the studies on different plants,it was found that vegetation wetlands had better nitrogen removal efficiency than non-vegetation wetland. The treatment efficacy of Phragmites australis wetland and polyculture wetland was better than Typha latifolia wetland. 展开更多
关键词 Vertical flow wetlands Domestic wastewater Removal of nitrogen and phosphorus Hydraulic retention time
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Effectiveness of a Subsurface Constructed Wetland on the Treatment of Saline Wastewater 被引量:7
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作者 Yushan Zhang Jing Wang Jinquan Qiu 《Journal of Environmental Science and Engineering》 2010年第1期9-13,共5页
This study evaluated the capability of a constructed wetland for treating saline wastewater. A pilot-scale constructed wetland system was set up and was initially operated at low, then increasing salt levels to determ... This study evaluated the capability of a constructed wetland for treating saline wastewater. A pilot-scale constructed wetland system was set up and was initially operated at low, then increasing salt levels to determine the effect of salinity on the contaminants' removal performance. The effect of hydraulic retention time (HRT) variation on treatment efficiency of the reed wetland was also discussed. Average removal efficiencies of the reed (Phragmites australis) wetland were found to be 79.0% for COD, 72.2% for ammonia nitrogen (NH3-N) and 82.8% for total phosphorus (TP). Reed planting had obvious improvement on COD and NH3-N removal efficiency when compared to an unplanted system. With the seawater proportion in the influent increasing from 20% to 30%, the TP removal efficiency improved obviously. COD removal efficiency of the reed wetland was positively correlated with HRT under high salinity condition, while excess HRT had adverse impacts on the NH3-N and TP removal. Optimal HRT for NH3-N and TP removal was 4 days. Results obtained can be beneficially used to improve the use of constructed wetlands in saline wastewater treatment. 展开更多
关键词 Constructed wetland saline wastewater hydraulic retention time reed.
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Monitoring population dynamics of the migratory Red-crowned Crane (Grus japonensis) at Shuangtaihekou National Nature Reserve,northeastern China,from 1991 to 2012 被引量:1
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作者 李玉祥 宋常站 +4 位作者 杨玉成 李晓静 李风丽 黄杰 黄秀艳 《Chinese Birds》 2012年第3期225-229,共5页
We studied migratory Red-crowned cranes from 1991-2012 in order to track population dynamics and trends for these cranes over time at Shuangtaihekou,northeastern China.Our results show that the earliest arrival date o... We studied migratory Red-crowned cranes from 1991-2012 in order to track population dynamics and trends for these cranes over time at Shuangtaihekou,northeastern China.Our results show that the earliest arrival date of the Red-crowned Crane (Grus japonensis) was usually around 1 March in the spring and the latest departure date of the cranes around 8 November.The peak period for the number of cranes observed in the spring was 10-20 March over these 22 years.The staging period in the spring is about 25 days.Comparing the highest number of Red-crowned cranes observed in the spring,the migratory population was around 400 birds in the 1990s,then,increased to over 800 birds in 2000.For a short while,the population maintained itself around 600-800 birds.After that,the population started to decline,until during the most recent years,we observed around 400 birds at peak times of each season.Our results match a similar population change pattern observed in the wintering area for a western population,which has been declining since 2000.There is an urgent need to reinforce protection and management,as well as to maintain and improve the quality of their habitats. 展开更多
关键词 Grus japonensis MIGRATION population dynamics Shuangtaihekou STOPOVER
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Structural Retrofitting of Old Illyria Hote
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作者 Feti Selmani Musa Stavileci 《Journal of Civil Engineering and Architecture》 2013年第12期1507-1513,共7页
Illyria hotel (formerly Bozhur) was built during the sixties in the heart of the actual Kosovo's capital Prishtina, according to former old Yugoslav standards in a Modernist architectural style. It represents a mas... Illyria hotel (formerly Bozhur) was built during the sixties in the heart of the actual Kosovo's capital Prishtina, according to former old Yugoslav standards in a Modernist architectural style. It represents a massive structural system with brick walls up to 54 cm thick and "avramenko" type reinforced concrete floors. The investor's aim was to add another two floors on the top of the existing ones and to build two level underground parking floors, a health spa centre, whilst at the vicinity of the existing building (the northern side) to erect a new 17 story-high brand new hotel and administration building. The retrofitting of the structure as well as construction of the new structure has been done in full accordance with the new structural Eurocodes' recommendations. 3D FEM (finite element method) modeling was used for the analysis and design, using ETABS v 9.5 nonlinear and ARSAP 2010 (Autodesk Robot Structural Analysis Professional 2010). Response spectrum design according to EC 8,3.2.2.4 has been used for seismic analysis and design with a reference peak ground acceleration on type A ground Of AgR = 0.25 g. 展开更多
关键词 Structural retrofitting reinforced concrete shear walls foundation strengthening column jacketing
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Stagnate to Extensive: The Design of Capital City Development in Coastal Archipelago Raja Ampat
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作者 Sri Astuti 《Journal of Civil Engineering and Architecture》 2012年第2期219-225,共7页
This discussion of Raja Ampat case, a subdivision of West Papua province, is related to the global warming issue where small islands will be narrowed as a result of sea level rise. Furthermore, it is related to autono... This discussion of Raja Ampat case, a subdivision of West Papua province, is related to the global warming issue where small islands will be narrowed as a result of sea level rise. Furthermore, it is related to autonomy regulations where each municipality and district has their own policy. The capital of Raja Ampat District in the east of Indonesia is developed from traditional place into central urban area. Raja Ampat, a naturally beautiful island, is located in a remote area famous for its diving spot for foreign tourists, amazing underwater life, bird watching, and to experience a traditional lifestyle with specific tropical fauna and flora. The problem is how to develop a city which needs to be in a stagnant extensive phase but: neither in vertical nor horizontal development to protect forest as conservation area due to limited land area. Identification and design methods used in this research is to develop settlement in Raja Ampat archipelago area which has around 610 large and small islands, atoll, and have 4.860 km shoreline with only 34 islands inhabited. The urban design for this archipelago of 1:6 ratios of land and ocean needs to be different, since it is dominated by water. With the limited land area resources, the development needs to be focused on the ocean area by optimizing land area. 展开更多
关键词 Coastal area sustainable design stagnant to extensive archipelago.
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Seismic hazard mitigation for nuclear power plant
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作者 Frieder Seible 《Engineering Sciences》 EI 2013年第3期2-9,共8页
The seismic safety of nuclear power plan(tNPP)has always been a major consideration in the site selection,design,operation,and more recently recertification of existing installations. In addition to the actual NPP and... The seismic safety of nuclear power plan(tNPP)has always been a major consideration in the site selection,design,operation,and more recently recertification of existing installations. In addition to the actual NPP and all their operational and safety related support systems,the storage of spent fuel in temporary or permanent storage facilities also poses a seismic risk. This seismic risk is typically assessed with state-of-the-art modeling and analytical tools that capture everything from the ground rupture or source of the earthquake to the site specific ground shaking,taking geotechnical parameters and soilfoundationstructureinteraction (SFSI) into account to the non-linear structural response of the reactor core,the containment structure,the core cooling system and the emergency cooling system(s),to support systems,piping systems and non-structural components,and finally the performance of spent fuel storage in the probabilistically determined operational basis earthquake (OBE) or the safe shutdown earthquake (SSE) scenario. The best and most meaningful validation and verification of these advanced analytical tools is in the form of full or very large scale experimental testing,designed and conducted in direct support of model and analysis tool calibration. This paper outlines the principles under which such calibration testing should be conducted and illustrates with examples the kind of testing and parameter evaluation required. 展开更多
关键词 seismic design seismic safety probabilistic hazard large scale testing full scale testing
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Residence Time Distribution at Laminar Pulsatile Flow in a Straight Pipe
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作者 Pavel Novotny Rudolf Zitny Hynek Chlup Jakub Kronek David Hromadka 《Journal of Chemistry and Chemical Engineering》 2011年第4期358-368,共11页
This paper deals with the problem of theoretical identification of the residence time distribution (RTD) characteristics of a straight pipe at laminar pulsatile flow, if tracer diffusion can be neglected. This situa... This paper deals with the problem of theoretical identification of the residence time distribution (RTD) characteristics of a straight pipe at laminar pulsatile flow, if tracer diffusion can be neglected. This situation is typical for micro-apparatuses (e.g. fluidic element) and also for flow in large arteries. Residence time distribution based on velocity profiles at pulsatile flow of a Newtonian liquid in a rigid pipe will be derived theoretically and compared with the well known results for a constant flow rate E(τ) = τ-^2/2τ^3 at τ 〉 τ^-/2, where E (τ) is differential distribution, x is residence time and τ^- is the mean residence time. The following part of the paper deals stimulus response experimental techniques using tracers. The principal problem related to laminar and convection dominated pulsatile flows is discussed: Can the impulse response also be identified with the actual residence time distribution in the case of variable flow? The general answer is no, and differences between RTD and impulse responses are evaluated as a function of the frequency and amplitude of pulsatile flows. 展开更多
关键词 Convective flow regime impulse response pulsatile flow residence time distribution
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小窗口
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作者 樊圣昂 卢新景(指导) 《东方少年(阅读与作文)》 2017年第2期33-33,共1页
小县城的街道两旁有许多小书亭。晌午刚过,一辆宝马车'唰'地停在一个书亭旁边。'王师傅,我来买书。'书亭的小窗口传出苍老的声音:'上次我给你选的《葡萄的栽培与嫁接》实用吗?'小伙子回答说:'非常好。这次... 小县城的街道两旁有许多小书亭。晌午刚过,一辆宝马车'唰'地停在一个书亭旁边。'王师傅,我来买书。'书亭的小窗口传出苍老的声音:'上次我给你选的《葡萄的栽培与嫁接》实用吗?'小伙子回答说:'非常好。这次我想买一本葡萄后期管理的书。'小窗口里很快递出书来。' 展开更多
关键词 书亭 窗口 葡萄 我来 地停
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