926 resultados para Glued laminated timber
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Knowledge about cumulative effects of forest management alternatives on forest landscape is required to make forest management decision. In this paper,a spatially explicit landscape model,LANDIS,was applied to simulate forest landscape changes in 200 years under four management alternatives (no cutting,clearcutting,selective cutting I and II) in Youhao Forestry Bureau located in Small Khingan Mountains. APACK was used to calculate distribution area of the representative species and species age cohort for six species. The results showed:1) timber harvest decreased area percentage of representative conifer species,Pinus koraiensis,Picea koraiensis and Picea jezoensis,Larix gmelinii to some extent compared to no cutting. The most influencing cutting mode for the area percentage of Tilia amurensis and Quercus mongolica was selective cutting II,followed by selective cutting I and clearcutting. To the contrast,the change of area percentage of Betula phatyphylla was contrary to the management alternatives; 2) As to species age cohort composition,timber harvest significantly changed age structure,that is,it decreased over-matured age cohort of representative species,and increased seedling and middle-age cohort (B. phatyphylla was not included,because its area percentage of over-mature age cohort was the highest under clearcutting than other three scenarios).
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沙产业是开发利用沙区地下、地面和地上的多种资源 ,创建沙地农业型和非农业型产业 ,形成产品系列生产 ,以获取持续规模的效益。制约沙产业发展的瓶颈因素是水。我国对沙区资源的开发利用已扩大到多个领域 ,沙区用材林基地建设、泥炭资源开发利用、热管技术应用、石油天然气开采等都初具规模。 2 1世纪将是沙产业崛起的世纪 ,发展沙产业前景广阔。
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A red color filter was laminated from a solution of red color pigment and an organo-soluble polyamide, based on 1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride (HQDPA) and 2,2'-dimethyl-4,4'-methylene dianiline (DMMDA). The red color filter in a polyamide matrix with negative birefringence plays an important role in twisted nematic liquid crystal displays (TN-LCDs). The red color filter, and also compensation films, extend the viewing angle of LCDs. (C) 1997 Elsevier Science S.A.
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大洋硅藻席沉积是硅藻大规模“勃发”的产物,且其样品采集具有很大的偶然性,本文利用在低纬度西太平洋136°~140°E,15°~21°N区域内首次发现的硅藻席沉积岩芯为研究对象,确定了成席硅藻的种类,探讨了硅藻席的时空分布,并对WPD03和WPD12两个岩芯的硅藻进行分析鉴定,通过对深海沉积硅藻组合的变化探讨低纬度西太平洋硅藻席形成时期的环境变化状况,进一步分析了该区域硅藻席沉积的形成机制。 通过研究,得出如下主要结论:1)出现于这一低纬西太平洋的硅藻席的成席藻类为“树荫种”硅藻Ethmodiscus rex(Wallich)Hendey;2)硅藻席发现站位成带状分布,大致呈北西-南东向展布,且大部分散布在17° N~20° N之间水深在CCD以下4837-6150m较平坦海底的深水区;3)经AMS14C测年结果显示,富含硅藻席的沉积物发生于16.0 ~ 28.6 ka B.P. 14C年期间,即“勃发”发生于末次冰期最盛期;4)在WPD 03和WPD 12两个岩芯共155个样品中共鉴定硅藻40属101种(含变种),且Thalassionema frauenfeldii的相对百分含量最高,Thalassionema nitzschioides、Azpeitia nodulifera、Nitzschia marina、Hemidiscus cuneiformis等次之,这五种硅藻占整个硅藻物种相对百分含量的85%左右,说明在该海域表层水体硅藻席沉积过程中,这五种硅藻最容易与成席硅藻在同时期的环境中生存,形成勃发;5)MIS3期的晚期,该区域表层海水盐度降低,这有助于该区水体的成层化,从而使“树荫种”硅藻开始勃发,导致“秋季倾泻”;6)末次冰期由于南极中层水(AAIW)北扩,南大洋中层水将富含硅酸盐的海水带入了研究区,即南大洋的“硅溢漏”作用,使该区域硅藻得以勃发,同时,铁输入的增多,可能也是造成硅藻勃发的主要原因之一。
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A dynamic model is built up by means of system dynamics method for the development offorest resources in Liaoning province.Prediction and strategy research are made for the fo-rest ecology and timber production in 2000 in Liaoning.The impactions of various designson the development of forest resources are understood by adjusting different parameters andadding disturbances to the model.Various parameters are determined according to the dataprovided by Land Dept.and Forestry Dept.of Liaoning province,the data of provincialforest statistics in 1978 is taken as the original values for running model,which is perfor-med on IBM PC/X7 computer in DYNAMO language of system dynamics.
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The Chinese Altai is one of the most important volcanogenic massive sulfide (VMS) deposit districts in China. All orebodies were lenticular or bedded and stratabounded by a suite of early Devonian volcanic-sedimentary rocks. Hydrothermal feeder zones developed under some of the orebodies. All the ores are massive or laminated, and show typical characteristics of VMS deposit. Based on the mineralizing time and the metal assembles, we divide 3 metallogenic stages: 1, Fe orefroming stage associated with basaltic and sedimentary rocks during very early Devonian; 2, Cu-Pb-Zn oreforming stage associated with rhyolitic and sedimentary rocks during early Devonian; 3, Cu-Zn oreforming stage in the dacitic and basaltic rocks during mid. Devonian. The hosting rocks for all orebodies are different, but they show very similar geochemical and isotopic characteristics. All the felsic rocks show enriched lighted rare earth elements (REE) patterns (La/Yb>5), and with an obvious Eu negative anomalies (Eu/Eu*<0.6). In the meanwhile, all the mafic rocks show flat REE pattern and no Eu anomalies. The Ashele basalt show an apparent Ce negative anomalies (Ce/Ce* <0.76), All the volcanic roks in Chinese Altai show the decoupled property between the high field strength elements (HFSE) and large ion lithophile elements (LILE). The negative Nb, Ta characteristics with respect to adjacent elements indicate that subduction-modified source. The Nd(t) of the hosting rocks for all orebodies changed in a small range (-1.5~5), and the (87Sr/86Sr)i change in a big range. The initial Sr value of the hosting rocks in Mengku and Tiemuerte are obviously affected by the seawater (0.705~0.710), and initial Sr values of hosting rocks Ashele change in a small range (0.704~0.706). All Sr-Nd isotopes of ores have the same range with the hosting rocks, indicating that both the ores and volcanic rocks have the same island arc source. The mean sulfur isotopes of sulfides from Ashele and Mengku are 6.2‰ and 3.4‰, respectively, indicating a deep magmatic source. However, the sulfur isotopes of sulfides from Keketale, Tiemuerte and Keyinbulake changed in -15.8‰~9.9‰, -23.5‰~1.87‰, -8.3‰~1.6‰, respectively. And the big sulfur isotope range indicated that the sulfur of the ores was a combination biogenic and magmatic source. All volcanic rocks from the VMS deposits in the southern Chinese Altai show a typical subduction related environments. Based on the regional and locally geological evidence, here we propose that the southern Chinese Altai is an island arc system, and all VMS deposits formed during the lateral accretion process. No VMS deposit formed during the formation of the island arc during Silurian; Fe VMS deposit formed during the beginning of the opening of the backarc basin in very early Devonian; Cu-Pb-Zn VMS deposits formed during the mature stage of the backarc basin in early Devonian; at last the Cu-Zn VMS deposit formed during the rifted stage of the island arc itself.
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Cambrian-Ordovician dolostones in Tarim Basin are hydrocarbon reservoir rocks of vital importance. Under the guidance of the theories of sedimentology and the sedimentology of carbonate reservoir, based on the first-hand qualitative and quantitative data especially, combined with micro-study, geochemical and reservoir capacity analysis, and precursor research, the origin and reservoir characteristics of the dolostones were discussed. Based on detailed petrographic investigations, four types of dolostone have been recognized, which are, respecitively, mud-silt-sized dolostones, algal laminated dolostones (ALD), prophyritic dolostone, and neomorphic dolostone. Mud-silt-sized dolostones always presents as laminas together with evaporated signatures, its REE patterns and ΣREE are all close to that of the finely crystalline limestone. This kind of dolomite probably experienced relatively low fluid-rock ratio during diagenesis was formed in hypersaline and oxidizing environment and involved fast dolomitization process. It was dolomitized by evaporated seawater in sabkha environment.The main primary fabrics of algal lamination in algal laminated dolomite (ALD) can still be identified and its ΣREE (21.37) is very close to that of algae. This reveals that ALD was dolomitized during early diagenesis and algae possibly played an important role. The ALD was formed under mediation of organic matter and Mg2+ were supplied by magnesium concentrated algal laminites and sea water. Prophyritic dolostones presents mainly as patchy occurrence and yield the lowest δ13C and Z value. Its ΣREE is much less than that of the finely crystalline limestone. These characteristics reveal that the cloudy cores were dolomitized in shallow early diagenetic environments by pore fluids riched in Mg2+. Whereas the clear rims were likely formed in subsequent burial into deeper subsurface environments, and the Mg2+ needed for further dolomitization possibly was supplied by the transformations of clay minerals. Neomorphic dolostones consist of coarse, turbid crystals and exhibits sucrosic and mosaic textures. It has highest Fe2+ contents and average homogeneous temperature (110.2℃). Collectively, these characteristics demonstrate that the neomorphic dolostones was likely formed by recrystallization of pre-existing dolomites during deep burial. The ΣREE of the four types of dolostone distinctly differentiates from each other. However, their REE patterns are all enriched in LREE, depleted in HREE and have Eu negative anomalies. Its ΣREE 13.64 ppm, less than 1/4 of finely crystalline limestone, and ranks the lowest in the 4 types.These characteristics are comparable to those of finely crystalline limestone, and are mainly infuenced by the sea water. These four types of dolostone show similar REE mobility behaviour and no significant fractionation, althouth they have been subjected to evidently different diageneses. Seven main pore types are identified in the dolostones , which are fenestral, moldic, intercrystal, dissolved,breccia, dissolved breccia and stylolite pores. Fenestral pores are primary and the others are secondary. The dissolved pores and intercrystal pores are the most important reservoir spaces and followed by breccias and dissolved breccia pores, and the moldic and fenestral pores are less important. Stylolites can enhance permeability of reservoir rocks in one hand, for the other hand, the capacity of reservoir and permeability are enhanced and then better reservoir rocks can be formed when they are combined with patchy dolostones. The relationship between porosity and the type of dolostones is that the dissolved neomorphic dolostones have the highest porosity of 3.65%, than followed by dissolved Mud-silt-sized dolostones of 3.35%. The mud-silt-sized dolostones without dissolution have the lowest porosity of 0.90%. Moreover, the porosity of prophyritic dolostones and the neomorphic dolostones without dissolution are lower, respectively 1.675% and 1.41%. Although algal laminated dolostones consist of euhedral crystals and riched in intercrystal pores, its porosity just yields 1.20%. The relationship between permeability and the type of dolostones is that that algal laminated dolostones have the highest permeability of 0.462mD and followed by 0.065mD of prophyritic dolostones. Dissolution have no significant influence on the permeability of neomorphic dolostones and this presented by the permeability of dissolved and non-dissolved are very close, respectively 0.043mD and 0.062mD. No matter dissolved or not, mud-silt-sized dolostones are much less permeable. The permeability of non-dissolved and dissolved are 0.051mD and 0.016mD. Collectively, in the study area, neomorphic dolostones can form high quality reservoir.
Using an Outdoor Learning Space to Teach Sustainability and Material Processes in HE product Design.
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The world is facing environmental changes that are increasingly affecting how we think about manufacturing, the consumption of products and use of resources. Within the HE product design community, thinking and designing sustainability’ has evolved to become a natural part of the curriculum. Paradoxical as the rise in awareness of sustainability increases there is growing concern within HE product design of the loss of workshop facilities and as a consequence a demise in teaching traditional object-making skills and material experimentation. We suggest the loss of workshops and tangible ‘learning by making skills’ also creates a lost opportunity for a rich learning resource to address sustainable thinking, design and manufacture ‘praxis’ within HE design education. Furthermore, as learning spaces are frequently discussed in design research, there seems to be little focus on how the use of an outdoor environment might influence learning outcomes particularly with regard to material teaching and sustainability. This 'case study' of two jewellery workshops, used outdoor learning spaces to explore both its impact on learning outcomes and to introduce some key principles of sustainable working methodologies and practices. Academics and students mainly from Norway and Scotland collaborated on this international research project. Participants made models from disposable packaging materials, which were cast in tin, in the sand on a local beach, using found timber to create a heat source for melting the metal. This approach of using traditional making skills, materials and nature was found to be a relevant contribution to a sustainable discourse.
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Plakhov, A.Y.; Torres, D., (2005) 'Newton's aerodynamic problem in media of chaotically moving particles', Sbornik: Mathematics 196(6) pp.885-933 RAE2008
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The study of medieval carpentry is probably one of the most neglected aspects of archaeological research in Ireland. The principal difficulty is the nature of the evidence, in that timber, unless the conditions are right, rarely leaves a trace above ground. The problem is further exacerbated by the fact that not a single medieval timber-framed building has survived in Ireland. Nevertheless, in recent years, in addition to the medieval roof of Dunsoghley, which up to quite recently was thought to be the only surviving roof structure in Ireland, a further eight medieval roof structures have been identified. Furthermore, an extensive corpus of early medieval mills, with evidence for advanced Roman carpentry techniques, has been excavated, while evidence for Viking houses, on what is probably the largest extant Viking settlement in Europe, have also been recovered. Although post and wattle structures dominate the archaeological record of the Viking period, nevertheless, it will be shown that the Roman tradition of carpentry, evidenced in the early medieval mills from the early seventh century, continued in use in the wider Gaelic community. And it is one of the pivotal points of this study, that with the takeover of Dublin by the Gaelic Irish in the late tenth century, this Roman carpentry tradition was gradually assimilated into the carpentry tradition of the Viking towns, which were now largely inhabited by a mixed population of Hiberno-Norse. Evidence for this Gaelic influence can be seen not only in the gradual replacement of the Viking post and wattle house by timber houses with load-bearing walls, but more importantly by the evidence for waterfront structures founded on baseplates with mortise and tenoned uprights on the pre-Norman waterfront in Cork. Furthermore, it will be shown, that the carpentry techniques used to build the Wood Quay revetments, shortly after the Anglo-Norman conquest in AD 1170, supports this contention.
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Leachate may be defined as any liquid percolating through deposited waste and emitted from or contained within a landfill. If leachate migrates from a site it may pose a severe threat to the surrounding environment. Increasingly stringent environmental legislation both at European level and national level (Republic of Ireland) regarding the operation of landfill sites, control of associated emissions, as well as requirements for restoration and aftercare management (up to 30 years) has prompted research for this project into the design and development of a low cost, low maintenance, low technology trial system to treat landfill leachate at Kinsale Road Landfill Site, located on the outskirts of Cork city. A trial leachate treatment plant was constructed consisting of 14 separate treatment units (10 open top cylindrical cells [Ø 1.8 m x 2.0 high] and four reed beds [5.0m x 5.0m x 1.0m]) incorporating various alternative natural treatment processes including reed beds (vertical flow [VF] and horizontal flow [HF]), grass treatment planes, compost units, timber chip units, compost-timber chip units, stratified sand filters and willow treatment plots. High treatment efficiencies were achieved in units operating in sequence containing compost and timber chip media, vertical flow reed beds and grass treatment planes. Pollutant load removal rates of 99% for NH4, 84% for BOD5, 46% for COD, 63% for suspended solids, 94% for iron and 98% for manganese were recorded in the final effluent of successfully operated sequences at irrigation rates of 945 l/m2/day in the cylindrical cells and 96 l/m2/day in the VF reed beds and grass treatment planes. Almost total pathogen removal (E. coli) occurred in the final effluent of the same sequence. Denitrification rates of 37% were achieved for a limited period. A draft, up-scaled leachate treatment plant is presented, based on treatment performance of the trial plant.
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This thesis is focused on the investigation of magnetic materials for high-power dcdc converters in hybrid and fuel cell vehicles and the development of an optimized high-power inductor for a multi-phase converter. The thesis introduces the power system architectures for hybrid and fuel cell vehicles. The requirements for power electronic converters are established and the dc-dc converter topologies of interest are introduced. A compact and efficient inductor is critical to reduce the overall cost, weight and volume of the dc-dc converter and optimize vehicle driving range and traction power. Firstly, materials suitable for a gapped CC-core inductor are analyzed and investigated. A novel inductor-design algorithm is developed and automated in order to compare and contrast the various magnetic materials over a range of frequencies and ripple ratios. The algorithm is developed for foil-wound inductors with gapped CC-cores in the low (10 kHz) to medium (30 kHz) frequency range and investigates the materials in a natural-convection-cooled environment. The practical effects of frequency, ripple, air-gap fringing, and thermal configuration are investigated next for the iron-based amorphous metal and 6.5 % silicon steel materials. A 2.5 kW converter is built to verify the optimum material selection and thermal configuration over the frequency range and ripple ratios of interest. Inductor size can increase in both of these laminated materials due to increased airgap fringing losses. Distributing the airgap is demonstrated to reduce the inductor losses and size but has practical limitations for iron-based amorphous metal cores. The effects of the manufacturing process are shown to degrade the iron-based amorphous metal multi-cut core loss. The experimental results also suggest that gap loss is not a significant consideration in these experiments. The predicted losses by the equation developed by Reuben Lee and cited by Colonel McLyman are significantly higher than the experimental results suggest. Iron-based amorphous metal has better preformance than 6.5 % silicon steel when a single cut core and natural-convection-cooling are used. Conduction cooling, rather than natural convection, can result in the highest power density inductor. The cooling for these laminated materials is very dependent on the direction of the lamination and the component mounting. Experimental results are produced showing the effects of lamination direction on the cooling path. A significant temperature reduction is demonstrated for conduction cooling versus natural-convection cooling. Iron-based amorphous metal and 6.5% silicon steel are competitive materials when conduction cooled. A novel inductor design algorithm is developed for foil-wound inductors with gapped CC-cores for conduction cooling of core and copper. Again, conduction cooling, rather than natural convection, is shown to reduce the size and weight of the inductor. The weight of the 6.5 % silicon steel inductor is reduced by around a factor of ten compared to natural-convection cooling due to the high thermal conductivity of the material. The conduction cooling algorithm is used to develop high-power custom inductors for use in a high power multi-phase boost converter. Finally, a high power digitally-controlled multi-phase boost converter system is designed and constructed to test the high-power inductors. The performance of the inductors is compared to the predictions used in the design process and very good correlation is achieved. The thesis results have been documented at IEEE APEC, PESC and IAS conferences in 2007 and at the IEEE EPE conference in 2008.
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Given a probability distribution on an open book (a metric space obtained by gluing a disjoint union of copies of a half-space along their boundary hyperplanes), we define a precise concept of when the Fréchet mean (barycenter) is sticky. This nonclassical phenomenon is quantified by a law of large numbers (LLN) stating that the empirical mean eventually almost surely lies on the (codimension 1 and hence measure 0) spine that is the glued hyperplane, and a central limit theorem (CLT) stating that the limiting distribution is Gaussian and supported on the spine.We also state versions of the LLN and CLT for the cases where the mean is nonsticky (i.e., not lying on the spine) and partly sticky (i.e., is, on the spine but not sticky). © Institute of Mathematical Statistics, 2013.
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This work proceeds from the assumption that a European environmental information and communication system (EEICS) is already established. In the context of primary users (land-use planners, conservationists, and environmental researchers) we ask what use may be made of the EEICS for building models and tools which is of use in building decision support systems for the land-use planner. The complex task facing the next generation of environmental and forest modellers is described, and a range of relevant modelling approaches are reviewed. These include visualization and GIS; statistical tabulation and database SQL, MDA and OLAP methods. The major problem of noncomparability of the definitions and measures of forest area and timber volume is introduced and the possibility of a model-based solution is considered. The possibility of using an ambitious and challenging biogeochemical modelling approach to understanding and managing European forests sustainably is discussed. It is emphasised that all modern methodological disciplines must be brought to bear, and a heuristic hybrid modelling approach should be used so as to ensure that the benefits of practical empirical modelling approaches are utilised in addition to the scientifically well-founded and holistic ecosystem and environmental modelling. The data and information system required is likely to end up as a grid-based-framework because of the heavy use of computationally intensive model-based facilities.