共查询到20条相似文献，搜索用时 31 毫秒
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Shunji Ouchi 《地球表面变化过程与地形》2021,46(5):1083-1095
Four runs of experimental landform development, with the same uplift rate, different rainfall intensity, and the same material of different permeability adjusted by the degree of compaction, showed complicated effects of rainfall and mound-forming material. In the run with more rainfall on less permeable material, low separated ridges developed in the uplifted area, because abundant overland flow promoted valley erosion and slope processes from early stages. In the run with less rainfall on less permeable material, valley incision proceeded mostly in major valleys where surface water converges. Canyons developed during early stages and later a high massive mountain emerged. The effect of rainfall difference, however, appeared completely opposite on more permeable material accompanied by lower shear strength. In the run with more rainfall on more permeable material, a massive mountain similar to that with less rainfall on less permeable material appeared, and low separated ridges appeared in the run with less rainfall on more permeable material as in the run with more rainfall on less permeable material. In the former case, similar amount of water available for Hortonian overland flow in early stages estimated from rainfall rate and permeability can explain the development of similar landforms. In the latter case, while abundant surface water with more rainfall on less permeable material made fluvial erosion active from early stages, the deficiency in surface water with less rainfall on more permeable material apparently attenuated fluvial erosion but possibly accentuated slope processes and slope failures by seepage water flow through more permeable material of low shear strength. The active erosion from early stages apparently resulted in the development of enduring similar low landforms later in the dynamic equilibrium stage. These experimental results indicate that similar landforms can emerge from different environmental and lithologic controls, and that process does not necessarily follow from form. 相似文献
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Dirk Goossens 《地球表面变化过程与地形》2005,30(4):443-460
Many stone‐covered surfaces on Earth are subject to aeolian deposition of atmospheric dust. This study investigates how the deposition of dust is affected when rock fragments become gradually more embedded in the ground or, inversely, become more concentrated on the surface. Experiments were executed in an aeolian dust wind tunnel with eight different types of pebbles. The following parameters were measured: dust deposition on the pebbles, dust deposition between and underneath pebbles, total dust deposition (pebbles + inter‐pebble space), and the fraction, of total deposition, of dust caught by the pebbles alone. The absolute amount of dust deposition and the dust deposition density (dust deposition per unit surface) were studied for each parameter. The effects exerted by pebble size, pebble flattening, pebble elongation and wind speed were also investigated. Dust patterns on and around pebbles were also studied via flow visualization. The absolute amount of dust settling on pebbles decreases the more that the pebbles become embedded. Dust deposition density on pebbles, on the other hand, increases with embedding. The more pebbles become embedded in the soil, the more efficient the process of dust deposition on pebbles becomes. Dust deposition between and underneath pebbles increases with pebble embedding. Dust deposition density between and underneath pebbles is maximum at 50 per cent embedding, showing that in this area dust deposition is most efficient when pebbles are halfway embedded. Total deposition slightly decreases the more pebbles become embedded, but total dust deposition density increases with embedding. Aerodynamic flow separation and diverging and converging airflow play an important role in the process of dust deposition on stone‐covered surfaces. The more pebbles protrude above the soil, the more they act as an obstacle and the more they disturb the air and dust flow creating scouring zones, flow separation bubbles and shelter areas for the dust. All these effects diminish as pebbles become more embedded in the soil. However, perturbations in dust patterns remain visible until pebbles have disappeared entirely. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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随着信息在社会发展中扮演着越来越重要的角色,地震信息对社会的影响也越来越明显。本文着重分析了地震信息失真传播的成因、特点以及对策,为管理地震信息提供借鉴。 相似文献
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In recent years, more and more studies are focused on the performance in seismic design instead of the strength of structures. People have realized that the structure deformation (displacement) can describe the damage more properly and directly than the strength (force). The displacement design spectra need to be constructed within more wide range of the period and the damping for the displacement-based seismic design. 相似文献
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Emili García-Berthou 《Aquatic Sciences - Research Across Boundaries》2001,63(4):466-476
The habitat and diet variation of the common carp (Cyprinus carpio) were studied in Lake Banyoles (Catalonia, Spain). Carp was the second most abundant species offshore and used more the littoral in spring and deep bottoms in winter. The diet of carp was based on detritus, amphipods (Echinogammarus sp.), phantom midge larvae (Chaoborus flavicans), diatom mucilages, and plant debris. Amphipods and phantom midge larvae were much more important in diet than previous studies found, because of their greater availability in this lake. Among the carp inhabiting deep waters, there was size-dependent variation in diet, with smaller carp selecting more meiobenthos (cladocerans, ostracods, and small chironomids) and larger carp preying on profundal macrobenthos (phantom midge larvae and large chironomids). Roach (Rutilus rutilus) and carp dominated in abundance the non-littoral zone of the lake and showed resource partitioning, with roach being a more efficient zooplanktivore and carp being more able to prey on hard material (plant seeds, mollusks, and ostracods). 相似文献
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论述了适用于遥测地震台网大震速报的一套计算机处理系统,系统设计以《全国遥测台网观测技术规范》和《近震分析》理论为依据,实现了数据输入,震相选择,数据处理,地震定位,震级计算,结果输出及贮存等多项功能,达到了快速确定地震三要素,提高速报速度和精度之目的,是一个较完善的,实用的速报系统。 相似文献
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Trinidad and Tobago beaches were periodically sampled for tar between July 1980 and September 1981. This project was carried out by the Institute of Marine Affairs in cooperation with the United Nations. The Caribbean coasts of both islands were almost pristine, whereas pollution on the Atlantic coast beaches was comparable to that of other coasts along major tanker routes. The source of high tar concentrations on the Atlantic coasts may be attributed to the residues from tanker bilge cleanings, which are carried along the South Equatorial Current, eventually to strand on the islands' beaches. In the dry season (January to April) north-westerly currents and north-easterly winds prevail and more tar strands on Trinidad than on Tobago. In the wet season (June to November), however, when currents are more northerly and south-easterly wind prevail, the reverse situation holds and more tar strands on Tobago. 相似文献
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随着地震科学技术的发展，地震科技信息作为学科窗口而越来越引起人们的重视。该文在阐述地震科技信息重要性的同时，又从本学科的基础、社会的需要、领导层的决策、多学科的利用及后效作用等方面，重点探讨了地震科技信息的综合价值，提出了发展地震科技信息工作的基本思路和地震科技信息逐步社会化的远景。 相似文献
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随着“互联网+”时代的到来,人们接受信息的方式发生了翻天覆地的变化,越来越多的人们尤其是年轻人更愿意通过移动App、门户网站等来获取信息。为了顺应时代的变化,防震减灾宣传平台也需要转变宣传工作形式,更加注重碎片化、即时性、形象化的传播。结合“互联网+”时代信息通讯的实际特点,在分析当前防震减灾宣传工作存在的重要问题基础上,以“互联网+”时代信息传递技术为主要发展特点,提出防震减灾科普知识泛在化宣传新模式,并根据泛在化宣传模式的特征,设计开发基于iOS系统的泛在化宣传资源,为防震减灾宣传工作提供基于移动设备的数字化资源支持。该研究对移动互联网时代地震科普宣传作了新的探讨与尝试,对于当前及未来全民普及防震减灾科学知识有积极的促进作用。 相似文献
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山西数字遥测地震台网地震编目及数据管理系统 总被引：2，自引：0，他引：2
介绍了山西数字遥测地震台网地震编目及数据管理软件开发的技术要点，分析了山西数字遥测地震台网系统集成后的资料产出问题，提出了解决的方案，指出该系统应朝着适用性、易用性、开放性的方向发展。 相似文献
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Mobility of lowland stream Trichoptera under experimental habitat and flow conditions 总被引：1，自引：0，他引：1
Piet F.M. Verdonschot Anna A. Besse-LototskayaDorine B.M. Dekkers Ralf C.M. Verdonschot 《Limnologica》2012,42(3):227-234
The species-specific mobility of six species of lowland stream Trichoptera was studied in flume experiments with different habitats and current flows. The test species were selected according to their occurrence along the environmental gradient from more natural towards highly disturbed sandy, lowland streams of the North-West European plain. Two groups of species were distinguished, three species occurring more frequently towards the natural end versus three occurring more frequently towards the disturbed end of the stream disturbance gradient. Experiments were conducted in a temperature and light controlled environment in indoor, re-circulating, man-made stream channels with four replicate gutters each. The bottom of each gutter held ten trays filled with five selected habitat materials (two trays each), which provided refugia and food. Three flow treatments with constant current velocities of 10, 30, or 50 cm/s were applied. Movements were scored based on visual observations of the position of each individual at fixed time points. The first day after release, individuals moved around very actively; this ‘release effect’ was removed from further analyses. The trichopteran species occurring near the more natural end of the disturbance gradient exhibited significantly less mobility (on average 10-15% of individuals actively moved around) than the species from the more disturbed end of the gradient (on average 30-40% of individuals actively moved around). The first group of trichopteran species also spent significantly longer times in the leaves habitat compared to the other three species, which moved more or less independent of habitat. With increasing current velocity, all test species moved more frequently, particularly the species from the more disturbed end of the gradient. This could indicate behavior to avoid dislodgement. The mobility of all species exceeded the mobility needed to use habitat resources of food and shelter, both present in excess. Therefore, short-term movement could also be (partly) a random behavior. Overall, the more tolerant species from the disturbed end of the gradient showed more mobility and flexibility than the species occurring under more or less natural stream conditions. This was consistent with the hypothesis that mobility is an adaptation of tolerant, ubiquitous species. Mobility is an adaptation of r-strategists. 相似文献
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Jones Keith Pascale Federica Wanigarathna Nadeeshani Morga Mariantonietta Sargin Sinan 《Bulletin of Earthquake Engineering》2021,19(10):4115-4143
Bulletin of Earthquake Engineering - As cities become larger and more densely populated the impacts of major earthquake events on city communities become more severe. Improving community resilience... 相似文献
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基于虚拟技术的地震应急指挥技术系统应用 总被引：1，自引：0，他引：1
地震应急指挥技术系统的特殊性要求整个系统必须具有高可靠性及稳定性.基于虚拟技术的地震应急指挥技术系统可实现整个系统的容灾备份,并通过虚拟机特性将原来在多台服务器上部署的系统在一台高性能服务器上实现,节约资源的同时,使异地移植更加灵活.基于虚拟技术的地震应急指挥技术系统,可提升整个系统的稳定性、灵活性、可靠性. 相似文献
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Science China Earth Sciences - Atmospheric refractivity fields are more strongly affected by more water vapor in the tropical lower troposphere than elsewhere. In this study, based on model... 相似文献