斯皮瓦克的“星球化”与比较文学——解读斯皮瓦克《一个学科的死亡》

斯皮瓦克在《一个学科的死亡》中,勾勒了她对比较文学这门学科发展的规划与分析。该书的第三章"星球化"是通过关注星球化这个自然的、未受政治破坏的星球概念,吁求一个触及世界前历史以及世界各个角落的星球化的比较文学。

世界中心、群岛与后现代制图术

在全球化进程不断推进的今天,其负面效应也日益显现:一方面,中心与边缘的二元对立愈加凸现,另一方面,差异性与他者性让位于对普世性的追寻,将我们所处的世界变成了一个同质化的"超级中心"。作者借鉴宋慧慈(Wai Chee Dimock)提出的"星球化"(planétarité/planetarity)概念、爱德华·格里桑(édouard Glissant)的"关系诗学"(poétique de relation)理论,以及程抱一论及中国画时的虚实观,提出从去中心化、多元中心化和偏离中心化的视角审视全球空间,强调不同地域和不同国家之间的平等性、相关联性和对话性,引导读者走出欧洲中心主义这一僵化而单一的思维模式。

旅游绅士化研究进展:理论脉络、研究议题与范式创新

旅游与绅士化日益紧密的联系从多维度展现了旅游发展与城乡社会空间重构的动态关联,旅游绅士化成为剖析这一现象背后政治经济和社会文化机制的重要理论视角。本研究对旅游绅士化研究的中西方相关文献进行系统梳理后发现:(1)旅游绅士化伴随着绅士化概念与发展阶段演变应运而生,并嵌入星球绅士化的研究议程中,其产生受到全球地方化理论、不平衡发展理论、资本循环理论和后殖民主义理论的深刻影响;(2)西方研究议题主要集中在旅游绅士化测度、旅游绅士化空间的生产与消费、旅游绅士化与旅游流动、旅游绅士化与短期租赁、旅游绅士化的影响效应及其应对等方面;(3)中国语境下独特的城乡关系、国家(政府)角色和制度设计能够为旅游绅士化理论的创新提供立足点;(4)受星球思维的影响,旅游绅士化通过聚焦旅游驱动社会空间不平衡发展的动态、联系与多尺度的过程,推进了新的研究范式。未来中国旅游绅士化研究需更加深入理解旅游驱动城乡人地关系转型的过程与机制,解析其中的社会公平和可持续发展问题,发挥旅游绅士化视角在维护空间正义和实现共同富裕方面的理论价值。

Synthesis of nanostructured Mg_2FeH_6 hydride and hydrogen sorption properties of complex

Reactive mechanical alloying(RMA)was carried out in a planetary ball mill for the synthesis of ternary hydride Mg2FeH6 for hydrogen storage.The formation mechanism of Mg2FeH6 in RMA process and the sorption properties of the products were investigated.The results show that Mg2FeH6 has a yield ratio around 80%,and a grain size below 10 nm in the powder synthesized by milling 3Mg+Fe mixture for 150 h under the hydrogen pressure of 1 MPa.The synthesized powder possesses a high hydrogen capacity and good sorption kinetics,and absorbs 4.42%(mass fraction)of hydrogen within 200 s at 623 K under the hydrogen pressure of 4.0 MPa.In releasing hydrogen at 653 K under 0.1 MPa,it desorbs 4.43%(mass fraction)of hydrogen within 2 000 s.The addition of Ti increases the hydrogen desorption rate of the complex in the initial 120 s of the desorption process.

Spatial and Quantitative Comparison of Satellite-Derived Land Cover Products over China

Because land cover plays an important role in global climate change studies, assessing the agreement among different land cover products is critical. Significant discrepancies have been reported among satellite-derived land cover products, especially at the regional scale. Dif- ferent classification schemes are a key obstacle to the comparison of products and are considered the main fac- tor behind the disagreement among the different products. Using a feature-based overlap metric, we investigated the degree of spatial agreement and quantified the overall and class-specific agreement among the Moderate Resolution Imaging Spectoradiometer （MODIS）, Global Land Cover 2000 （GLC2000）, and the National Land Cover/Use Data- sets （NLCD） products, and the author assessed the prod- ucts by ground reference data at the regional scale over China. The areas with a low degree of agreement mostly occurred in heterogeneous terrain and transition zones, while the areas with a high degree of agreement occurred in major plains and areas with homogeneous vegetation. The overall agreement of the MODIS and GLC2000 products was 50.8% and 52.9%, and the overall accuracy was 50.3% and 41.9%, respectively. Class-specific agree- ment or accuracy varied significantly. The high-agreement classes are water, grassland, cropland, snow and ice, and bare areas, whereas classes with low agreement are shru- bland and wetland in both MODIS and GLC2000. These characteristics of spatial patterns and quantitative agree- ment could be partly explained by the complex landscapes, mixed vegetation, low separability of spectro-temporal- texture signals, and coarse pixels. The differences of class definition among different the classification schemes also affects the agreement. Each product had its advantages and limitations, but neither the overall accuracy nor the class-specific accuracy could meet the requirements of climate modeling.

Application of Remote Sensing for Mangrove Mapping： A Case Study of AI-Dhakira, the State of Qatar

In recent years, the pressure of increasing coastal industries and tourism activities has, in some areas, led to the clearing of many coastal habitats along the Qatar＇s shorelines for the construction of tourist resorts, tourism-related development and industrial facilities. Such threats are leading to the increasing demand for detailed mangrove maps for the purpose of measuring the extent of decline in mangrove ecosystems. Detailed mangrove maps at the community or species level are, however, not easy to produce, mainly because mangrove forests are very difficult to access. Without doubt, remote sensing is a serious alternative to traditional field-based methods for mangrove mapping, as it allows information to be gathered from the forbidding environment of mangrove forests, which otherwise, logistically and practically speaking, would be extremely difficult to survey. Remote sensing applications for mangrove mapping at the fundamental level are already well established but, surprisingly, a number of advanced remote sensing applications have remained unexplored for the purpose of mangrove mapping at a finer level. Consequently, the aim of this paper is to unveil the potential of some of the unexplored remote sensing techniques for mangrove studies. Temporal Landsat TM image of 1986, Landsat ETM image of 2000 and Resourcesat-1 LISS 3 image of 2008 are used to calculate percentage change in mangrove cover at AI Dhakira site using geometrically registered and radiometrically corrected historical Landsat and Resourcesat-1 images. Region masks are employed to isolate the unwanted area from the images. NDVI （normalized difference vegetation index） is used to detect mangroves using near-infrared and red bands which are computed from the satellite images. The ground-truthing visit to AI Dhakira site is conducted to confirm the results of the analysis. Change detection is applied and mangrove in the study area is found to have decreased by about 8.79% from 2000 to 2008.

“垂死”之由、“新生”之路——评斯皮瓦克的《学科之死》

斯皮瓦克的《学科之死》在西方学界引起了强烈的反响，该书对我们重新审视西方比较文学特别是美国比较文学，尤其是探讨其“垂死”之由、“新生”之路，并进而反思我们的比较文学发展，具有重要的参考意义。本文评介论析了斯皮瓦克观点的独创之见和不足之处，进而探讨了该书给予我们的思考与启示。

Research on global change scientific satellites

Global change now poses a severe threat to the survival and development of mankind.Large-scale,real-time,highly accurate Earth observation from space has become a key technology used to observe global change.China is one of the most influential countries affecting and being affected by global change,yet it has no scientific satellite for global change research so far.Developing global change scientific satellites not only would meet an important demand of China,but also would be a valuable contribution to the world.By analyzing the mechanisms of space-based observation of variables sensitive to global change,this paper explores the concept of global change scientific satellites,and proposes a series of global change scientific satellites to establish a scientific observation system for global environmental change monitoring from space.

Venus round trip using solar sail

Trajectory optimization and simulation is performed for Venus round trip (VeRT) mission using solar sail propulsion. Solar gravity is included but atmospheric drag and shadowing effects are neglected in the planet-centered escape and capture stages. The spacecraft starts from the Geostationary orbit (GEt) at a predetermined time to prepare a good initial condition for the Earth-Venus transfer, although the launch window is not an issue for spacecraft with solar sails. The Earth-Venus phase and the return trip are divided into three segments. Two methods are adopted to maintain the mission trajectory for the VeRT mis- sion and then compared through a numerical simulation. According to the first approach, Planet-centered and heliocentric ma- neuvers are modeled using a set of blended analytical control laws instead of the optimal control techniques. The second pro- cedure is the Direct Attitude Angle Optimization in which the attitude angles of the solar sail are adopted as the optimization variables during the heliocentric transfer. Although neither of the two methods guarantees a globally optimal trajectory, they are more efficient and will produce a near-optimal solution if employed properly. The second method has produced a better result for the minimum-time transfer of the VeRT mission demonstrating the effectiveness of the methods in the preliminary design of the complex optimal interplanetary orbit transfers.

Optimizing the Gabor Bandwidth of satellite navigation signals by MCS signal expression

Satellite navigation is playing an important role in social life.The performances of the services a navigation system provides are the concern of the builders and users.The signal structure determines the inherent ability of a satellite navigation system to provide these services.Therefore,it is necessary and reasonable to optimize the signal in the initial design.The waveforms of signals in satellite navigation chips are an important aspect of the signal's structure,which impact the characteristics of the autocorrelation function and power spectrum in the time domain and frequency domain.The range accuracy of a navigation system is usually described by its Gabor Bandwidth.The Gabor Bandwidth of the Binary Offset Carrier (BOC) modulation in next-generation GNSS signal systems is not optimal.This paper presents a signal expression based on Multilevel Coded Symbol (MCS) signals,which can describe the fine structure of navigation signals.With this expression,we can optimize the Gabor Bandwidth of the signal,and find out the corresponding MCS vector and chip waveform,so as to get higher range accuracy.The method in this paper,in theory,is of great value in the design of next-generation navigation signals.

Response of magnetic fields at geosynchronous orbit and on the ground to the sudden changes of IMF B_Z

The rapid change in the Earth’s magnetosphere caused by solar wind disturbances has been an important part of the solar wind-magnetosphere interaction.However most of the previous studies focused on the perturbation of the Earth’s magnetic field caused by solar wind dynamic pressure changes.In this paper,we studied the response of geosynchronous magnetic field and the magnetic field to the rapid southward turning of interplanetary magnetic field during the interval 1350 1420 UT on 7May 2007.During this event,BZ component of the interplanetary magnetic field decreased from 15 nT to 10 nT within 3 min(1403 1406 UT).The geosynchronous magnetic field measured by three geosynchronous satellites(GOES 10 12)first increased and then decreased.The variations of magnetic field strength in the morning sector(9 10 LT)were much larger than those in the dawn sector(5 LT).Meanwhile,the H components of geomagnetic field on the ground have similar response features but exhibit latitude and LT dependent variations.Compared with H components,the D components do not have regular variations.Although the solar wind dynamical pressure encounters small variations,the magnetic field both in space and on the ground does not display similar variations.Therefore,the increase of geomagnetic field in the dawn sector is caused by the southward turning of IMF(interplanetary magnetic field)BZ.These results will help to better understand the coupling process of geomagnetic filed and interplanetary magnetic field.