排序方式： 共有157条查询结果，搜索用时 0 毫秒
71.
Merab G. Tsagareli 《Journal of the history of the neurosciences》2013,22(4):393-408
This article is dedicated to one of the outstanding scientists of the nineteenth century: Ivane Tarkhnishvili (Tarchanoff), a Russian physiologist of Georgian origin who graduated from the St. Petersburg Medico-Surgical Academy and worked under the supervision of the founder of Russian physiology, Ivan Sechenov. Among his numerous contributions was the discovery of the skin galvanic reflex; however, Tarkhnishvili's most significant contribution was the discovery of the influence of X-rays on the central nervous system, animal behavior, the heart and circulation, and embryonic development. Indeed, these works have given rise to a new field in science (radiobiology). 相似文献
72.
Mariana Correia Luis Guerrero Anthony Crosby 《Conservation and Management of Archaeological Sites》2013,15(3):224-256
The preservation of earthen architectural heritage is extremely complex due to the diversity of its constituent materials and potentially rapid physical deterioration. Interventions on historic earthen architecture throughout the world have shown very distinct levels of success, but there is no single procedure or combination of conservation procedures that guarantee success. One of the problems is the lack of knowledge about the behaviour of soil as the material component, and its relationships both with other materials, and associated natural and cultural environments. This article analyses some technical considerations that have influenced the preservation of earthen archaeological remains, through critical analysis of the existing bibliographic references from the proceedings of specialized international conferences that have taken place in the last twenty years. 相似文献
73.
A. BLAKEBOROUGH 《Journal of Earthquake Engineering》2013,17(1):69-92
Occasionally there is an earthquake in the UK during which church bells are reported to have been set ringing. The motion of a medium sized church bell has been simulated and the response to earthquake records from the Parkfield earthquake of 1966 has been calculated. The response of the bells is found to depend on the mechanical properties of the bell and the tower in which it is hung. The analyses do show that for a bell to ring in an earthquake the peak ground acceleration is in the range 0.97 to 29.4 m s?2 considerably in excess of the range indicated by the MMI VI “church and school bells ring” of 0.4 to 1.5 m s?2. The best correlation between recognised earthquake parameters and the ringing of the bell was obtained by combining the spectral values for clapper-bell angle, obtained from the linearised set of equations, at the bells natural frequencies using the SRSS method. The values of this parameter to set the bell ringing was in the range 0.25 and 0.38 rad, compared with the actual striking angle 0.54 rad. 相似文献
74.
GUILLAUME POUSSE∗ CATHERINE BERGE-THIERRY LUIS FABIAN BONILLA PIERRE-YVES BARD 《Journal of Earthquake Engineering》2013,17(4):547-574
The Eurocode 8 (EC8) currently proposes two standard shapes for the design response spectra. Type 1 spectra are enriched in long period and are suggested for high seismicity regions. Conversely, Type 2 spectra are proposed for low to moderate seismicity areas (like France), and exhibit both a larger amplification at short period, and a much smaller long period contents, with respect to Type 1 spectra. These propositions, however, were constrained using few events mostly recorded on analogical instruments. In the present study, we use the Japanese high quality digital K-net array in order to evaluate the proposed ECS response spectra. Furthermore, all K-net stations have geotechnical characterisation. We first constructed a database of shallow events, depth less than 25 km, to avoid subduction related records. The database spans six years of seismicity from 1996 until 2003. Thus, 591 events were selected with moment magnitude between 4 and 7.3, recorded at 691 stations, giving a total of 6812 two horizontal components accelerograms. Using these records, we computed spectral ground-motion prediction equations and we used them to review the shape of the proposed EC8 spectra. In particular, we studied the plateau-PGA ratio level, the period interval where this plateau is constant, and site amplification effects. The results show surprisingly that the Type 2 rock better envelope the Japanese data. Another interesting observation is that the K-net data corresponding to all soil classes are rich in short periods around 0.1 s. This characteristic has not been observed in other worldwide databases. Normalised empirical predictions show a widening of the plateau as the soil conditions degrade. This suggests that the Type 2 EC8 spectra do not cover enough the long periods for EC3-soil classes C, D and E. Finally, the computed ground-motion prediction equations show that the peak ground acceleration (PGA) is nearly invariant to the soil conditions. Soil effects are mainly seen in the shape and plateau level. 相似文献
75.
In the last century alone two to three million people died in earthquakes; More than 240 000 perish in Tangshan earthquake in China, 20 000 in the Izmit [Ikeya, 2004] 50 000 in India Bhuj earthquake, 100000 in Sumatra and 90000 in Pakistan earthquakes. Earthquake engineering has progressed to the stage where it is now computationally practical and desirable to perform a dynamic analysis of most civil engineering structures. Such an analysis requires the engineer to create an accurate analytical model of the structures as well as prescribe an earthquake input excitation. The design earthquake input excitation for the site under consideration is usually prescribed in the form of response spectra or in the form of an ensemble of artificial earthquake acceleration time histories. There is every need for generating artificial accelerograms since recorded accelerograms are very limited at site. This paper proposes five neural network based models for the generation of artificial earthquake and response spectra using wavelet transforms (WT) and principal component analysis (PCA) where the recorded accelerograms are limited at site of interest. The proposed model is compared with Lee and Han's model. The data for 25 earthquakes are taken for training and 4 for testing. Just like response spectra, this is also a convenient way of obtaining the design solution to a structural dynamics problem and is certainly an important tool. 相似文献
76.
THERESE LINDGREN MARIA R. NILSEN 《Tijdschrift voor economische en sociale geografie = Journal of economic and social geography = Revue de géographie économique et humaine = Zeitschrift für ?konomische und soziale Geographie = Revista de geografía económica y social》2012,103(2):196-208
Safety in green spaces was examined within residential areas with multi‐family housing in Swedish towns. The focus was on a specific type of space in order to identify elements important for the feeling of safety in that realm. The method used was qualitative interviews with residents and housing company staff. Housing staff and residents emphasised good lighting and low vegetation as important elements for feeling safe. Another key element raised by residents was knowing and recognising people in the area and being able to place them in appropriate contexts. Low shrubs and lighting improved the view. Visibility had a close connection to viewing other people and distinguishing between desirable and undesirable people, a classification aided by knowledge about residents in the area. The three elements lighting, cut shrubs and knowledge about neighbours are all contextualised and given meaning here in a broader understanding of how safety is experienced. 相似文献
77.
The delegation of decision‐making capacity from one actor to another—known variously as authority or control—is a central phenomenon of organizational sociology. Despite its theoretical and practical significance, however, the dynamics of control within disrupted settings (such as disasters) remain poorly understood. Here, we shed light on this question by a reexamination of historical data on multiorganizational disaster response networks, using recently developed statistical methods for robust inference from error‐prone informant reports. Specifically, we test competing hypotheses about the relationship of control during the response process to the structure of interorganizational communication. We find that both the realized and normative response hierarchies are likely shaped by coordination among both nonadjacent alters and along indirect channels. Our results suggested that the communication structure of these networks is consistent with a control at a distance model of command. This article makes a substantial contribution to understanding the role of network structure in the emergence of control between organizations in disrupted settings. Additionally, our innovative approach to network inference will guide researchers in dealing with error‐prone data in their own research on policy networks. 相似文献
78.
建国以来女性教育的成果、问题及对策 总被引：2，自引：0，他引：2
女性的教育状况是衡量女性在社会中地位高低的主要标志之一.新中国建立后制定的有关法律和法规,新的教育体制的确立以及开展的女性扫盲运动、女性基础教育、高等教育、研究生教育、留学教育和继续教育等实践,使中国女性在提高了政治和社会地位的同时,也提高了文化知识水平和科学技术的应用能力.教育是立国之本,而女性教育更关系到民族的兴亡和国家的盛衰.占中国人口一半以上的女性自身素质和文化水平曾对建国以来的社会发展产生过很大影响,并将继续对21世纪中国科技、经济、社会的走向产生巨大的影响. 相似文献
79.
AbstractDisease outbreaks and pandemics have long played a role in societal and economic change. However, the nature of such change is selective, meaning that it is sometimes minimal and, at other times, and change or transformation may be unexpected, potentially even reinforcing contemporary paradigms. A comprehensive overview of pandemics and their effects is provided. This is used to help contextualise the COVID-19 pandemic, its impact on tourism and government, industry and consumer response. Drawing on the available literature, factors that will affect tourism and destination recovery are then identified. Some measures will continue or even expand present growth orientations in tourism while others may contribute to sustainability. It is concluded that that the selective nature of the effects of COVID-19 and the measures to contain it may lead to reorientation of tourism in some cases, but in others will contribute to policies reflecting the selfish nationalism of some countries. However, the response to planetary limits and sustainable tourism requires a global approach. Despite clear evidence of this necessity, the possibility for a comprehensive transformation of the tourism system remains extremely limited without a fundamental transformation of the entire planet. 相似文献
80.