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1.
通过分析1980年以后的海冰资料和卫星云图照片,对黄、渤海沿岸11个海冰测点的历史变迁进行了评述,浅析了测点的优劣及使用资料时应注意的事项。 相似文献
2.
Lin-gun Liu C.-C. Lin Y. J. Yung T. P. Mernagh T. Irifune 《Physics and Chemistry of Minerals》2009,36(3):143-149
K-lingunite is a high-pressure modification of K-feldspar that possesses the tetragonal hollandite structure. Variations of
the Raman spectra of K-lingunite were studied up to ~31.5 GPa at room temperature, and in the range 79–823 K at atmospheric
pressure. The Raman frequencies of all bands were observed to increase with increasing pressure, and decrease with increasing
temperature for K-lingunite. This behavior is in line with those observed for most of other materials. New sharp Raman bands
appear at pressures greater than 13–15 GPa, suggesting a phase transition in K-lingunite with increasing pressure. The transition
is reversible when pressure was released. The appearance of these new Raman bands may correspond to the phase transition revealed
earlier at around 20 GPa by X-ray diffraction studies. Instead of transforming back to its stable minerals, such as orthoclase,
microcline or sanidine, K-lingunite became amorphous in the temperature range 803–823 K at atmospheric pressure. 相似文献
3.
Perceptions of climate engineering in the South Pacific,Sub-Saharan Africa,and North American Arctic
Nearly all research on public perceptions of climate engineering has been conducted in wealthy, developed countries. However, understanding perspectives from vulnerable populations is critical to inclusive, democratic debate on both research and governance. This study utilized in-depth interviews to explore the perspectives of vulnerable populations in the South Pacific, Sub-Saharan Africa, and the North American Arctic. Interviewees in this study were desperate for solutions to climate change and therefore willing to consider climate engineering. However, their willingness to consider climate engineering could be characterized as both deeply reluctant and highly conditional. Interviewees expressed a number of concerns about potential social and political implications of engineering the climate. They also described conditions that may need to be met to ensure that future climates (engineered or otherwise) are more equitable. 相似文献
4.
In the conventional structural seismic analysis, the rigid base model is usually adopted without considering the flexibility of the ground, leading to inaccurate estimation of the vibration characteristics and the seismic response of the structure. In 2007, several in situ tests were conducted by the National Center for Research on Earthquake Engineering (NCREE) on the school buildings in the Guanmiao Elementary School in Tainan, Taiwan. For the study of soil–structure interaction (SSI) effects, the forced vibration test (FVT) was performed, and the deformation of the foundation system was measured during the pushover test. In this paper, the results of these in situ tests are presented and discussed, and the finite element models of the school buildings were generated for the simulation of the FVT and for the pushover analysis in order to investigate the difference between the rigid base model and the flexible base model. Results show that the mechanical properties of the structure and the foundation could be demonstrated in these in situ tests. Additionally, the introduction of the flexibility of the foundation has a considerable influence on the results of structural analysis. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
5.
In Global Navigation Satellite System (GNSS) positioning, the receiver measures the pseudorange with respect to each observable
navigation satellite and determines the position and clock bias. In addition to the GPS, several other navigation satellite
constellations including Glonass, Galileo and Compass can/will also be used to provide positioning, navigation, and timing
information. The paper is concerned with the solvability of the navigation problem when the receiver attempts to process measurements
from different constellations. As two different constellations may not be time-synchronized, the navigation problem involves
the determination of position of the receiver and clock bias with respect to each constellation. The paper describes an analytic
approach to account for the two-constellation navigation problem with three measurements from one constellation and two measurements
from another constellation. It is shown that the two-constellation GNSS navigation problem becomes the solving of a set of
two simultaneous quadratic equations or, equivalently, a quartic equation. Furthermore, the zero-crossover of the leading
coefficient and the sign of the discriminant of the quartic equation are shown to play a significant role in governing the
solvability, i.e., the existence and uniqueness of the navigation solutions.
相似文献
Jyh-Ching JuangEmail: |
6.
Yung C. Shang Dr. 《GeoJournal》1985,10(3):299-305
The economics of aquaculture is reviewed on two levels: micro and macro. Micro-economics in aquaculture deals mainly with the management measures and elements affecting the efficiency of operation at the farm level, while macro-economics addresses the assessment of social benefits and costs of an aquaculture project. If aquaculture is socially beneficial but unattractive to private investors, public support on credit, marketing, extension, training, and research may be appropriate, especially during the early stages of development.The importance of economic analysis is emphasized since it provides a basis not only in the decision making of the individual farmer, but also in the formulation of aquaculture policies. Thus, greater attention should be focused on the improvement of economic data for analysis. 相似文献
7.
Long-term changes in water quality and phytoplankton characteristics in port shelter, Hong Kong, from 1988-1998. 总被引:6,自引:0,他引:6
This study analysed monthly physico-chemical and phytoplankton data collected from 10 marine monitoring stations in Port Shelter Hong Kong, from 1988 to 1998. Cluster analysis based on all water quality parameters measured shows that the 10 monitoring stations can be grouped into three clusters: Cluster I consists of stations located in Outer Port Shelter; Cluster II consists of stations located in Inner Port Shelter and Cluster III consists of a single station in Hebe Heaven, a well-sheltered Bay in Inner Port Shelter. Factor analysis shows high positive loadings for nutrients and nutrient ratios in the first two factors of the three clusters, which indicates that the stations of the three clusters were primarily grouped according to their respective nutrient conditions. In Inner Port Shelter, and particularly Station PM5 in the sheltered Hebe Haven, the influence of surface runoff and pollution loading from the surrounding catchment area was apparent. Five stations located along a transect from Inner to Outer Port Shelter were selected for trend analysis. An increasing trend for temperature and a decreasing trend for pH are observed in all Stations except PM10 which is at the mouth of Port Shelter. The results of canonical analysis revealed that temperature and pH could also play an important role in determining the density and biovolume of the minor algal groups in Port Shelter. 相似文献
8.
Wylie A. Carr Christopher J. Preston Laurie Yung Bronislaw Szerszynski David W. Keith Ashley M. Mercer 《Climatic change》2013,121(3):567-577
There have been a number of calls for public engagement in geoengineering in recent years. However, there has been limited discussion of why the public should have a say or what the public can be expected to contribute to geoengineering discussions. We explore how public engagement can contribute to the research, development, and governance of one branch of geoengineering, solar radiation management (SRM), in three key ways: 1. by fulfilling ethical requirements for the inclusion of affected parties in democratic decision making processes; 2. by contributing to improved dialogue and trust between scientists and the public; and 3. by ensuring that decisions about SRM research and possible deployment are informed by a broad set of societal interests, values, and framings. Finally, we argue that, despite the nascent state of many SRM technologies, the time is right for the public to participate in engagement processes. 相似文献
9.
The recently discovered water vapor plumes on Saturn's moon Enceladus, the polar caps of planet Mars and the possible ice volcanism on the Jovian satellites call for suitable techniques to explore deep ice layers of the solar system bodies. This paper presents a novel approach to deliver scientific probes into deeper layers of planetary ice. Several existing locomotion concepts and techniques for such probes are presented. After studying the mathematical framework of the melting locomotion process, melting tests with different head forms were done to evaluate the influence of the head's geometry on the melting process. This work led to a novel concept of a thermal drill head, using heat and mechanical drill in combination to penetrate the ice. We compare the performance of such a hybrid concept versus the melting penetration alone by a mathematical model and tests in ice with a prototype of the melting drill head. 相似文献
10.
Shear‐type buildings with Maxwell model‐based brace–damper systems are studied in this paper with a primary emphasis on the effects of brace stiffness. A single‐story building with a viscous damper installed on top of a Chevron‐brace is first investigated. Closed‐form solutions are derived for the simple structure, relating the brace stiffness and damper coefficient to the targeted reduction in response displacement or acceleration. For a given brace stiffness, the solution is minimized to give a set of formulae that will allow the optimal damper coefficient to be determined, assuring the desired performance. The model is subsequently extended to multistory buildings with viscous dampers installed on top of Chevron‐braces. For a targeted reduction in the mean square of the interstory drift, floor acceleration or base shear force, the minimum brace stiffness and optimal damper coefficients are obtained through an iterative procedure. The response reduction, which signifies the improved performance, is achieved by a combination of brace stiffness and viscous damper coefficients, unlike conventional approaches where damper coefficients are typically optimized independent of brace stiffnesses. Characteristics of multi‐degree‐of‐freedom systems are studied using a 2‐story and a 10‐story buildings where the effects of brace stiffness on the overall performance of the building can be quantified. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献