移动通信基站天线电磁辐射分布规律及安全防护

指出了随着通信行业在我国不断发展,用户量持续增加,为了满足话务容量和网络覆盖率的需求,三大通信运营商开始将大量的移动通信基站建设起来,特别是在城市中,修建了许多基站。尽管这些基站提升了移动网络运营效率,然而,也会增加环境中的电磁辐射总量,所以,掌握移动通信基站天线电磁分布规律及制定安全防护对策非常必要,需要给予高度重视。     

虹口区移动通信基站电磁辐射环境影响探讨

为满足居民愈发增长的各项通信需求,移动通信基站的同步建设紧随其后。虹口区位于上海中心城区,南部黄浦江和苏州河沿岸更是处于新时期高速发展状态,其中旧区改造和新片区规划发展需要更加完善的移动通信基站覆盖网络,同时居民的环境保护意识也越来越强,发展的过程中双方产生的误解会影响虹口区整体通信网络建设。通过收集区内移动通信基站电磁辐射监测数据,探讨了影响基站电磁辐射监测数据大小的可能因素,提出了移动通信基站优化选址、居民自身距离防护等建议,希望能对区内移动通信基站建设和居民环境保护要求起到借鉴作用。     

“全球星”卫星移动电话在林业工作中的应用

卫星移动通讯是近几年通讯领域的新生力量，其无可比拟的全球“无缝隙”覆盖和对地形的高适应性，可作为森林防火通讯指挥系统和林业勘察及林业执法等工作的可信赖的通讯保障。“全球星”卫星移动通讯网是由美国劳拉公司和高通公司发起创建，并由中国电信等多家通信公司参股的卫星移动通信系统。该系统采用４８颗绕地球运行的低轨道卫星，在全球范围内提供“无缝隙”覆盖卫星移动通信业务，在地面通讯网覆盖不到的地形复杂地区或无人区发挥作用，是地面通讯网的延伸和补充。另外，“全球星”系统采用简单直接的设计理念，最大限度地减少使用…     

浅谈移动通信宏基站的环保管理

通过理论计算的方式,对移动通信宏基站所使用的设备是否需要进行环保管理进行了说明.同时,利用绍兴地区电磁环境监测现状监测数据,计算了移动通信宏基站正常运行时所产生的电磁辐射量,并根据现状监测结果,对照相关电磁辐射防护标准,探讨了移动宏通信基站在正常工况下是否可以满足现有的国家标准.     

移动通信基站在森林防火工作中的应用

移动通信基站基于卫星系统和通信系统的相关技术已相对成熟,在森林防火工作中已逐渐推广应用。本文根据工程实例,简要阐述了移动通信基站在森林防火工程项目中的应用。     

南充市移动通信基站周围电磁环境现状调查

为了减消民众对移动通信基站电磁辐射的恐惧心理,对南充市移动通信基站周围电磁环境进行了监测,结合《电磁环境控制限值》(GB 8702-2014)与《辐射环境保护管理导则电磁辐射环境影响评价方法与标准》(HJ/T 10.3-1996)对监测结果进行了评价,结果表明:南充市移动通信基站周围电磁辐射水平均低于国家相关标准,且辐射水平较低。     

数字化变电站综合测控装置通讯中断故障对电网的影响

针对110 kV五村数字化变电站多次出现站内综合测控装置模块通讯中断信号,且调度监控系统无法获得监控信息不能及时处理,多次遭到用户投诉电压异常。就测控装置通讯异常及导致的一系列情况进行深入分析,着重了解测控装置的特点,有助于提高变电高运行人员对数字化变电站的巡视技巧,对目前存在的异常现象提出了解决方案。     

新疆天然林资源保护工程智能化监控平台建设研究

基于移动通信、地理信息和视频监控等技术建立天然林资源保护工程智能化监控平台,实现天然林资源的全面监控和管理,加强巡护人员和巡护事件的监控力度。文中介绍了视频监控技术、移动GIS技术和智能移动通信技术等研究中的关键技术。阐述平台总体框架设计以及视频监控管理子系统、天保工程森林智能移动巡护子系统和天然林资源保护巡护管理子系统的主要功能实现。     

卫星移动通信技术在林业工作中的应用

卫星移动通信业务作为通讯领域的新生力量 ,以其随时随地接通的卓越优势 ,将在各个领域发挥其不可替代的作用。卫星移动通信业务的主要特点是不受地理环境、气候条件和时间的限制 ,在卫星覆盖区域内无通讯盲区 ,使其成为覆盖地域、空域、海域的无国界限制的全球通信网络 ,特别是在目前其他类型通信系统难以覆盖的区域 ,卫星移动通信更可大展身手。在林业工作中 ,特别是在森林防火、灭火、森林勘察业务中 ,经常会遇到下列问题 :因作业地区地形极为复杂 ,距人口密集地区距离遥远 ,目前的有线通信不可能延伸进来 ,而目前主要使用的常规无线对讲…     

移动通讯市场世界需求旺盛

据韩国经济新闻报道称,由于美、日等发达国家对移动通讯的需求出现《爆炸性增长》,到二零零零年,世界移动通讯市场有望扩大到目前的两倍以上。其中,手提电话、汽车电话等,将由目前的五千三百三十万部猛增     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.