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A decline in snow cover area of Passu and Ghulkin valleys between 1995 and 2022
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作者 Imran HUSSAIN Mumtaz ALI +6 位作者 Sher MUHAMMAD Wajid HASSAN Salar ALI Zakir HUSSAIN Syed Hammad ALI Shaukat ALI Muhammad Younis KHAN 《Journal of Mountain Science》 SCIE CSCD 2023年第12期3542-3551,共10页
The global cryosphere is experiencing accelerated melting due to climate change.Currently,the Karakoram anomaly is under discussion with a debate about the possibility that the anomaly may have recently ended.This stu... The global cryosphere is experiencing accelerated melting due to climate change.Currently,the Karakoram anomaly is under discussion with a debate about the possibility that the anomaly may have recently ended.This study aims to evaluate the up-to-date changes in snow cover in the western Karakoram region.We observed the snow cover changes in Passu and Ghulkin valleys in the Hunza River basin(HRB)of the Karakoram through multitemporal Landsat satellite data between 1995 and 2022.We found a significant reduction in snow cover in these valleys,with an average reduction rate of 0.42 km~2/yr,resulting in a total reduction of~11.46 km~2 between 1995 and 2022.This reduction in snow cover is consistent with the mass loss of glaciers in the Karakoram region in recent years.The decline in snow cover in these valleys is also consistent with the meteorological data.The temperature in summer(June)has significantly increased whereas the precipitation in the accumulation season(March)has decreased.These rapid changes suggest that it is crucially important to monitor the snow cover on a regular basis to support downstream management of snowmelt runoff.In addition,there is a need of planning for mitigation and adaptation strategies for snow-related hazards. 展开更多
关键词 CRYOSPHERE Snow covers area Climate change KARAKORAM
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Restoration of Folk Document Covers from the Qing Dynasty to the Republic of China
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作者 Jiao Yao Fujiang Geng +1 位作者 Huanhuan Wang Yunpei Lu 《Paper And Biomaterials》 CAS 2023年第3期66-74,共9页
The covers of booklets and books in folk documents primarily serve to protect the pages.Owing to long-term storage limitations,a considerable number of book covers have suffered varying degrees of damage.Following the... The covers of booklets and books in folk documents primarily serve to protect the pages.Owing to long-term storage limitations,a considerable number of book covers have suffered varying degrees of damage.Following the principles of restoration,a comparative analysis and restoration of folk document covers were conducted,selecting four different types of carriers from the Taihang Mountain Documents,ranging from the Qing dynasty to the Republican Era.These carriers included hemp,mulberry bark,and machinemade paper,and cotton blue cloth.Each cover type was matched with an appropriate restoration paper,and different methods were employed during the restoration process.Through restoration,the previously damaged document covers can continue to fulfill their role in protecting the books,thereby extending the lifespan of these four folk documents. 展开更多
关键词 RESTORATION folk documents COVERS
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A novel non-separation opening scheme of front cover for rocket launch canister 被引量:1
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作者 Ce Zhang Xin Zhao +2 位作者 Zonglai Mo Zhuoyu Guo Jun Li 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2019年第6期905-911,共7页
In view of that existing opening technologies of front cover for rocket launch canister have disadvantages such as causing damage on the ground equipment,not being reused and easily broken.A novel reusable non-separat... In view of that existing opening technologies of front cover for rocket launch canister have disadvantages such as causing damage on the ground equipment,not being reused and easily broken.A novel reusable non-separation spring-driven opening scheme is proposed to achieve rapid and reliable opening of the front cover.The mathematical model of the opening process of the front cover is established by the rigid body dynamics theory.To establish a response surface model to optimize the opening scheme,three main influencing factors of the opening process are obtained through the designed experiments,including the pre-compression,the stiffness of the thrust spring,and the thrust spring force arm length.In addition,the prescribed kinematic law was taken as constraint,and the smaller thrust spring preliminary pressure and angular velocity was taken as optimization expectations.The results show that the opening scheme meets the design requirements on opening process well.It also shows that the optimized scheme can reduce the kinetic energy of the front cover,and the impact on the canister effectively,achieving a reliable and rapid opening of the front cover. 展开更多
关键词 Canister covers Spring-driven Non-separation Optimized opening scheme Rocket launch canisters Launch safety
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Land Use and Land Cover Changes in a Tropical River Basin: A Case from Bharathapuzha River Basin, Southern India 被引量:2
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作者 P. P. Nikhil Raj P. A. Azeez 《Journal of Geographic Information System》 2010年第4期185-193,共9页
A study of the spatial and temporal changes in land use and land cover (LULC) was conducted using Remote Sensing and GIS. We analyzed the LULC of Bharathapuzha river basin, south India using multispectral LANDSAT imag... A study of the spatial and temporal changes in land use and land cover (LULC) was conducted using Remote Sensing and GIS. We analyzed the LULC of Bharathapuzha river basin, south India using multispectral LANDSAT imageries of 1973-2005 time periods. 31% depletion in the natural vegetation cover and 8.7% depletion in wetland agriculture area were seen in the basin during the period. On the other hand the urban spread in the basin increased by 32%. The study highlights the need for a scientific management plan for the sustainability of the river basin, keeping in view the recent climatic anomalies and hydrological conditions of the basin. 展开更多
关键词 LAND Use and LAND COVERS (LULC) Bharathapuzha River BASIN RS GIS
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Use of Evapotranspiration (ET) Landfill Covers to Reduce Methane Emissions from Municipal Solid Waste Landfills 被引量:1
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作者 Tarek Abichou Tarek Kormi +3 位作者 Cheng Wang Haykel Melaouhia Terry Johnson Stephen Dwyer 《Journal of Water Resource and Protection》 2015年第13期1087-1097,共11页
Solid waste landfills need to have final covers to 1) reduce the infiltration of rainfall into the waste mass and 2) reduce surface greenhouse gas emissions. Most regulations require that such final covers include hyd... Solid waste landfills need to have final covers to 1) reduce the infiltration of rainfall into the waste mass and 2) reduce surface greenhouse gas emissions. Most regulations require that such final covers include hydraulic barriers, such as compacted clays with or without geomembrane. Significant research has been undertaken to allow the use of evapotranspiration-based covers (often termed: Evapotranspiration (ET) Cover, Water Balance Covers, or Phyto Covers) as an alternative to the barrier concept covers. ET covers are designed so that they have the capacity to store water by the soil and also have plants or vegetation to remove the stored water. In ET covers, plant roots can enhance the aeration of soil by creating secondary macropores which improve the diffusion of oxygen into soil. Therefore, biological methane oxidation (a natural process in landfill soils) can be improved considerably by the soil structuring processes of vegetation, along with the increase of organic biomass in the soil associated with plant roots. This paper summarizes a study to investigate the capacity of an ET cover to reduce surface greenhouse gas emissions when implemented on a solid waste landfill. This study consisted of using a numerical model to estimate methane emission and oxidation through an ET cover under average climatic conditions in Bennignton, Nebraska, USA. Different simulations were performed using different methane loading flux (5 to 200 gm-2·d-1) as the bottom boundary. For all simulations, surface emissions were the lowest during the growing season and during warmer days of the year. Percent oxidation is the highest during the growing season and during warmer days. The lowest modeled surface emissions were always obtained during the growing season. Finally, correlations between percent oxidation and methane loading into simulated ET covers were proposed to estimate methane emissions and methane oxidation in ET covers. 展开更多
关键词 EVAPOTRANSPIRATION COVERS METHANE Oxidation LANDFILLS GREENHOUSE Gas Emissions
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Farm-Scale Applicability of Three Covers (Peat, Polystyrene Balls and Synthetic Sheet Roof) to Reduce Ammonia Emissions from Pig Slurry Storage 被引量:1
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作者 Laurence Loyon Fabrice Guiziou +1 位作者 Sylvie Picard Patricia Saint-Cast 《Agricultural Sciences》 2016年第6期396-406,共11页
Covering the slurry pit has been shown to be one of the best ways to reduce ammonia emissions (NH<sub>3</sub>) during manure management. Yet, few studies have been conducted at farm scale. We studied the f... Covering the slurry pit has been shown to be one of the best ways to reduce ammonia emissions (NH<sub>3</sub>) during manure management. Yet, few studies have been conducted at farm scale. We studied the feasibility of three cover materials (peat, polystyrene balls and synthetic sheet roof) to reduce ammonia (NH<sub>3</sub>) emissions during on-farm storage of pig slurry. The impact on greenhouse gas emissions, methane (CH<sub>4</sub>), nitrous oxide (N<sub>2</sub>O) and carbon dioxide (CO<sub>2</sub>) of covering the slurry pit was also evaluated. Simultaneous field experiments were carried out using two similar pits at a farm with peat and polystyrene ball covers, which allowed direct comparison of the feasibility of the two covers to reduce gas emissions (measured using the dynamic chamber technique). Emissions from the third option (using a synthetic sheet roof) were estimated by measuring the concentrations in the headspace under the cover and the air leakage from the cover with a tracer gas (CO<sub>2</sub>). Results showed that the polystyrene balls cover reduced emissions of NH<sub>3</sub> during storage by up to 80% whatever the season, but increased potential greenhouse gas emissions by 20% in summer. No consistent reduction was achieved with the peat cover even though some individual results seemed to indicate up to 25% reduction in ammonia emissions;moreover, there was a 30% increase in CH<sub>4</sub> and CO<sub>2</sub> emissions during the storage period. The use of a synthetic sheet roof enabled up to 90% reduction in NH<sub>3</sub>, CH<sub>4</sub> and CO<sub>2</sub> emissions whatever the season. 展开更多
关键词 Ammonia Slurry COVERS Farm-Scale Measurement PIG
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How to Enlarge the Students' Vocabulary:in English Learning
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作者 洪筠 《海外英语》 2011年第7X期318-319,共2页
Vocabulary is a very important element in English learning.Without a large vocabulary,no one can reach a high English level.However,it is very difficult to enlarge vocabulary.In fact there are many methods to enlarge ... Vocabulary is a very important element in English learning.Without a large vocabulary,no one can reach a high English level.However,it is very difficult to enlarge vocabulary.In fact there are many methods to enlarge vocabulary. 展开更多
关键词 IMPORTANCE Enlarge VOCABULARY assoation word formation coversation MOVIE culture PAY
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Numerical Simulations of Jet Flow Inside Launching Box and Design of Pressure Opening the Covers of Missile Launching Box
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作者 刘琦 郝继光 +1 位作者 姜毅 陈建伟 《Journal of Beijing Institute of Technology》 EI CAS 2004年第S1期54-57,共4页
Numerical simulations are presented for jet flow inside a launching box. The predictions are based on solutions of the unsteady three-dimensional Reynolds-averaged Navier-stokes equations. Since the pressure opening t... Numerical simulations are presented for jet flow inside a launching box. The predictions are based on solutions of the unsteady three-dimensional Reynolds-averaged Navier-stokes equations. Since the pressure opening the forward cover is given, the pressure opening the backward cover is designed by analyzing the flow field inside the launching box. The κ -ε turbulent model is presented and the structured meshes are used through the whole computational field. 展开更多
关键词 launching box the pressure opening the covers jet flow
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Innovative strategies and nutritional perspectives for fortifying pumpkin tissue and other vegetable matrices with iron
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作者 Marina F.de Escalada Pla Silvia K.Flores Carolina E.Genevois 《Food Science and Human Wellness》 SCIE 2020年第2期103-111,共9页
The present review article focuses on different technological strategies and nutritional perspectives having added advantage to human health in fortifying vegetables matrices with iron.An introduction to the main aspe... The present review article focuses on different technological strategies and nutritional perspectives having added advantage to human health in fortifying vegetables matrices with iron.An introduction to the main aspects related to iron deficiency consequences is resumed in order to understand the importance of developing new strategies for improving iron intake.In this sense,the tendencies and alternatives will also be discussed.Emerging technologies like impregnation or dry infusion are presented as sustainable options for obtaining structured fortified vegetables.A review about the usefulness of edible covers for stabilizing micronutrients and/or probiotic microorganisms in fortified matrices is also analysed.Since iron deficiency still continue to be a worldwide health issue,innovating in food fortification remains a challenge for researchers and food manufactures. 展开更多
关键词 VEGETABLES IRON Ascorbic acid PROBIOTICS Edible covers
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Investigation and Evaluation of Ground Covers in Botanical Garden of Chengdu
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作者 SONG Xiaomei XIAO Xi LI Shaocai 《Journal of Landscape Research》 2014年第2期50-53,56,共5页
After investigating species and application forms of ground covers in Botanical Garden of Chengdu, the application quality evaluation system was established from the perspective of ornamental, adaptive and applicable ... After investigating species and application forms of ground covers in Botanical Garden of Chengdu, the application quality evaluation system was established from the perspective of ornamental, adaptive and applicable characteristics of ground covers, AHP and K-Means adopted to evaluate and grade major ground covers. The results showed that there are 93 ground cover species in Botanic Garden of Chengdu, belonging to 82 genera of 47 families. Major application means of the ground covers in the garden were introduced, covering fl ower bed, roadside, waterfront, under woods, lawn, rockery decoration. Application quality of the 38 major ground covers was evaluated comprehensively, and the qualifi cation rate achieved 97.39%, i.e. these plants are able to meet ecological, beautifying and social functions in the garden. 展开更多
关键词 Ground covers APPLICATION EVALUATION Analytic hierarchy process Chengdu
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Power Stripping of Asbestos-Containing Insulation from Electrical Cable
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作者 Charles L. Blake Giffe T. Johnson Raymond D. Harbison 《Occupational Diseases and Environmental Medicine》 2019年第3期65-74,共10页
Efforts to recycle copper from electrical conductors have led to the development of specialized machines, which automatically remove insulating covers from wires and cable products. In the past, certain wire and cable... Efforts to recycle copper from electrical conductors have led to the development of specialized machines, which automatically remove insulating covers from wires and cable products. In the past, certain wire and cable products were insulated using chrysotile asbestos. This research was undertaken to determine the asbestos fiber exposure risks associated with power stripping machinery to remove asbestos-containing insulation materials from electrical wire or cable. A Rigby Machinery, Inc., Model 4H electric powered wire/cable insulation stripping machine was acquired along with approximately 42 m of asbestos insulated cable. During two separate, but nearly identical, test sessions, a laborer used the wire stripper to remove the asbestos-containing insulation from the subject cable. This work took place within a closed metal building with a total interior volume of 2500 m3. Industrial hygiene personal and area air samples were collected for airborne fibers throughout all wire stripping periods. Collected air samples were analyzed using phase contract microscopy (PCM) and transmission microscopy (TEM). The results of analysis using PCM for personal samples (n = 3) taken during periods of continuous cable stripping activity showed test period airborne fiber exposures ranging from 0.034 to 0.068 (mean 0.056 f/cc). Follow-up analysis of these personal samples using TEM indicated asbestos adjusted PCM exposures ranging from 0.017 to 0.045 (mean 0.033 f/cc). Area air samples taken at distances ranging from 2 to 9 meters from the wire stripper (n = 16) showed asbestos adjusted PCM concentrations ranging from less than 0.0001 to 0.041 f/cc (mean 0.007 f/cc). The process of power stripping asbestos-containing insulation from electrical wires and cables can cause exposure to airborne asbestos fibers. However, the levels of such exposure are not expected to exceed the current occupational exposure limits for asbestos of 0.1 f/cc as an 8-hr TWA or 1.0 f/cc averaged over a 30-minute exposure period. 展开更多
关键词 Asbestos Exposure Insulating COVERS POWER STRIPPING ELECTRICAL Wire CHRYSOTILE Asbestos Asbestos Fibers Asbestos-Related Disease Asbestos-Containing Material
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Parametric analyses of evapotranspiration landfill covers in humid regions
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作者 Wenjie Zhang Cheng Sun 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2014年第4期356-365,共10页
Natural soils are more durable than almost all man-made materials. Evapotranspiration (ET) covers use vegetated soil layers to store water until it is either evaporated from the soil surface or transpired through ve... Natural soils are more durable than almost all man-made materials. Evapotranspiration (ET) covers use vegetated soil layers to store water until it is either evaporated from the soil surface or transpired through vegetation. ETcovers rely on the water storage capacity of soil layer, rather than low permeability materials, to minimize percolation. While the use of ET covers in landfills increased over the last decade, they were mainly used in arid or semi-arid regions. At present, the use of ET covers has not been thoroughly investigated in humid areas. The purpose of this paper is to investigate the use of ETcovers in humid areas where there is an annual precipitation of more than 800 mm. Numerical analyses were carried out to investigate the influences of cover thickness, soil type, vegetation level and distribution of precipitation on performance of ET covers. Performance and applicability of capillary barriers and a new-type cover were analyzed. The results show that percolation decreases with an increasing cover thickness and an increasing vegetation level, but the increasing trend becomes unclear when certain thickness or LAI (leaf area index) is reached. Cover soil with a large capability of water storage is recommended to minimize percolation. ET covers are significantly influenced by distribution of precipitation and are more effective in areas where rainy season coincides with hot season. Capillary barriers are more efficient than monolithic covers. The new cover is better than the monolithic cover in performance and the final percolation is only 0.5% of the annual precipitation. 展开更多
关键词 Evapotranspiration (ET) covers Humid areas Parametric analyses Performance
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Algebraic Characterization of SSC of Uni-Cyclic Multigraphs
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作者 Imran Ahmed Shahid Muhmood 《Algebra Colloquium》 SCIE CSCD 2023年第2期325-338,共14页
We introduce first the spanning simplicial complex(SSC)of a multigraph g,which gives a generalization of the SSC associated with a simple graph G.Combinatorial properties are discussed for the SSC of a family of uni-c... We introduce first the spanning simplicial complex(SSC)of a multigraph g,which gives a generalization of the SSC associated with a simple graph G.Combinatorial properties are discussed for the SSC of a family of uni-cyclic multigraphs U_(n)^(r),m with n edges including r multiple edges within and outside the cycle of length m,which are then used to compute the f-vector and Hilbert series of face ring k[△s(U_(n)^(r),m)]for the SSC △s(U_(n)^(r),m)(un,m).Moreover,we find the associated primes of the facet ideal I_(F)(△s(U_(n)^(r),m).Finally,we device a formula for homology groups of △s(U_(n)^(r),m) prove that the SsC of a family of uni-cyclic multigraphs is Cohen-Macaulay. 展开更多
关键词 simplicial complexes spanning trees Hilbert series vertex covers Betti numbers
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Teahouses In Chengdu
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作者 林锋 《初中生学习指导》 2023年第26期50-50,共1页
There is a saying,“China has the best teahouses in the world and Chengdu has the best teahouses in China.”Chengdu has not only many teahouses but also the special ways of serving and drinking tea.As soon as the visi... There is a saying,“China has the best teahouses in the world and Chengdu has the best teahouses in China.”Chengdu has not only many teahouses but also the special ways of serving and drinking tea.As soon as the visitors enter the teahouses,the waiters or waitresses will greet them with teapots and cups in their hands.The cups often have special covers and saucers.The covers can keep the water warm. 展开更多
关键词 China. COVERS houses
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Album recording Wuhan's painted manhole covers
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作者 Deng Xiaolong 《Changjiang Weekly》 2023年第2期6-6,共1页
For more than 10 years,Mr.Ma has been taking photos of manhole covers that havepictures on them.He has found over 100 in the streets and alleys of Wuhan and has finally organized many of them into a book.Recently,he p... For more than 10 years,Mr.Ma has been taking photos of manhole covers that havepictures on them.He has found over 100 in the streets and alleys of Wuhan and has finally organized many of them into a book.Recently,he posted a"Wuhan manhole cover album"on social media,which has attracted a large number of followers. 展开更多
关键词 RECORDING finally COVERS
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Two-dimensional numerical manifold method with multilayer covers 被引量:6
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作者 LIU ZhiJun ZHENG Hong 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第4期515-530,共16页
In order to reach the best numerical properties with the numerical manifold method(NMM),uniform finite element meshes are always favorite while constructing mathematical covers,where all the elements are congruent.In ... In order to reach the best numerical properties with the numerical manifold method(NMM),uniform finite element meshes are always favorite while constructing mathematical covers,where all the elements are congruent.In the presence of steep gradients or strong singularities,in principle,the locally-defined special functions can be added into the NMM space by means of the partition of unity,but they are not available to those complex problems with heterogeneity or nonlinearity,necessitating local refinement on uniform meshes.This is believed to be one of the most important open issues in NMM.In this study multilayer covers are proposed to solve this issue.In addition to the first layer cover which is the global cover and covers the whole problem domain,the second and higher layer covers with smaller elements,called local covers,are used to cover those local regions with steep gradients or strong singularities.The global cover and the local covers have their own partition of unity,and they all participate in the approximation to the solution.Being advantageous over the existing procedures,the proposed approach is easy to deal with any arbitrary-layer hanging nodes with no need to construct super-elements with variable number of edge nodes or introduce the Lagrange multipliers to enforce the continuity between small and big elements.With no limitation to cover layers,meanwhile,the creation of an even error distribution over the whole problem domain is significantly facilitated.Some typical examples with steep gradients or strong singularities are analyzed to demonstrate the capacity of the proposed approach. 展开更多
关键词 numerical manifold method finite element method COVERS hanging nodes structured local refinement short cracks
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Reliable and Energy Efficient Target Coverage for Wireless Sensor Networks 被引量:4
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作者 Jing He Shouling Ji Yi Pan Yingshu Li 《Tsinghua Science and Technology》 SCIE EI CAS 2011年第5期464-474,共11页
A critical aspect of applications with Wireless Sensor Networks (WSNs) is network lifetime. Power-constrained WSNs are usable as long as they can communicate sense data to a processing node. Poor communication links... A critical aspect of applications with Wireless Sensor Networks (WSNs) is network lifetime. Power-constrained WSNs are usable as long as they can communicate sense data to a processing node. Poor communication links and hazardous environments make the WSNs unreliable. Existing schemes assume that the state of a sensor covering targets is binary: success (covers the targets) or failure (cannot cover the targets). However, in real WSNs, a sensor covers targets with a certain probability. To improve WSNs' reliability, we should consider that a sensor covers targets with users' satisfied probability. To solve this problem, this paper first introduces a failure probability into the target coverage problem to improve and control the system reliability. Furthermore, we model the solution as the a-Reliable Maximum Sensor Covers (a-RMSC) problem and design a heuristic greedy algorithm that efficiently computes the maximal number of a-Reliable sensor covers. To efficiently extend the WSNs lifetime with users' pre-defined failure probability requirements, only the sensors from the current active sensor cover are responsible for monitoring all targets, while all other sensors are in a low-energy sleep mode. Simulation results validate the performance of this algorithm, in which users can precisely control the system reliability without sacrificing much energy consumption. 展开更多
关键词 target coverage wireless sensor networks energy efficiency sensor scheduling α-reliable maximum sensor covers node failure
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GALOIS TRIPLE COVERS OF SURFACES 被引量:2
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作者 谈胜利 《Science China Mathematics》 SCIE 1991年第8期935-942,共8页
The basic theory on Galois triple covers is developed in this paper. For Galois triplecovers, it is proved that the singularities can be resolved by a canonical method, and someformulas for the invariants are found.
关键词 SURFACES TRIPLE COVERS INVARIANTS resolution of singularities.
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Mapping fractional cropland covers in Brazil through integrating LSMA and SDI techniques applied to MODIS imagery 被引量:1
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作者 Changming Zhu Xin Zhang Qiaohua Huang 《International Journal of Agricultural and Biological Engineering》 SCIE EI CAS 2019年第1期192-200,共9页
MODIS time-series imagery is promising for generating regional and global land cover products.For Brazil,however,accurate fractional cropland covers(FCC)information is difficult to obtain due to frequent cloud coverag... MODIS time-series imagery is promising for generating regional and global land cover products.For Brazil,however,accurate fractional cropland covers(FCC)information is difficult to obtain due to frequent cloud coverage and the mixing-pixel problem.To address these problems,this study developed an innovative approach to mapping the FCC of the Mato Grosso State,Brazil through integrating Linear Spectral Mixture Analysis(LSMA)and Seasonal Dynamic Index(SDI)models.With MOD13Q1 time-series EVI imagery,a SDI was developed to represent the phenology of croplands.Furthermore,fractional land covers(e.g.,vegetation,soil,and low albedo components)were derived with the LSMA algorithms.A stepwise regression model was established to estimate the FCC at the regional scale.Finally,ground truth cropland cover information was extracted from Landsat TM imagery using a hybrid method.Results indicated that the combination of multiple feature variables produced better results when compared with individual variables.Through cross-validation and comparative analysis,the coefficient of determination(R^(2))between the reference and estimated FCCs reached 0.84 with a Root Mean Square Error(RMSE)of 0.13.This indicates that the proposed method effectively improved the accuracy of fractional cropland mapping.When compared to the traditional per-pixel“hard”classification,the sub-pixel level maps illustrated detailed cropland spatial distribution patterns. 展开更多
关键词 fractional cropland covers(FCC) MODIS enhanced vegetation index(EVI) subpixel mapping remote sensing
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Variables separated equations:Strikingly different roles for the Branch Cycle Lemma and the finite simple group classification 被引量:1
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作者 FRIED Michael D. 《Science China Mathematics》 SCIE 2012年第1期1-72,共72页
Davenport's Problem asks:What can we expect of two polynomials,over Z,with the same ranges on almost all residue class fields? This stood out among many separated variable problems posed by Davenport,Lewis and Sch... Davenport's Problem asks:What can we expect of two polynomials,over Z,with the same ranges on almost all residue class fields? This stood out among many separated variable problems posed by Davenport,Lewis and Schinzel.By bounding the degrees,but expanding the maps and variables in Davenport's Problem,Galois stratification enhanced the separated variable theme,solving an Ax and Kochen problem from their Artin Conjecture work.Denef and Loeser applied this to add Chow motive coefficients to previously introduced zeta functions on a diophantine statement.By restricting the variables,but leaving the degrees unbounded,we found the striking distinction between Davenport's problem over Q,solved by applying the Branch Cycle Lemma,and its generalization over any number field,solved by using the simple group classification.This encouraged Thompson to formulate the genus 0 problem on rational function monodromy groups.Guralnick and Thompson led its solution in stages.We look at two developments since the solution of Davenport's problem.Stemming from MacCluer's 1967 thesis,identifying a general class of problems,including Davenport's,as monodromy precise.R(iemann)E(xistence)T(heorem)'s role as a converse to problems generalizing Davenport's,and Schinzel's (on reducibility).We use these to consider:Going beyond the simple group classification to handle imprimitive groups,and what is the role of covers and correspondences in going from algebraic equations to zeta functions with Chow motive coefficients. 展开更多
关键词 group representations normal varieties Galois stratification Davenport pair Monodromy group primitive group COVERS fiber products Open Image Theorem Riemann's existence theorem genus zero problem
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