“丛”思维与乡村旅游发展模式创新——以江苏省泰州市为例

近年来,乡村旅游业得到了快速发展,但也出现了区域整体竞争力问题。根据泰州市实际,要促进乡村旅游的整体发展,提高乡村旅游的区域竞争力,关键需要"丛思维"。要以"丛"思维推进规划"域"布局,通过"域"布局,实现区"域"旅游发展一体化、特色化、差异化。要以"丛"思维推进景区"群"发展,通过"群"发展,形成乡村旅游景区网状开发机制、景区结盟运营机制、景区良性竞争机制。要以"丛"思维推进景点"簇"建构。通过"簇"建构,促进景点开发模式、资源利用模式、景点建构模式的创新。

A Gridless Router Based on Hierarchical PB Corner Stitching Structure

A multi layer gridless area router is reported.Based on corner stitching,this router adopts tile expansion to explore path for each net.A heuristic method that penalizes nodes deviating from the destination is devised to accelerate the algorithm.Besides,an enhanced interval tree is used to manage the intermediate data structure.In order to improve the completion rate of routing,a new gridless rip up and rerouting algorithm is proposed.The experimental results indicate that the completion rate is improved after the rip up and reroute process and the speed of this algorithm is satisfactory.

Distribution pattern of rare plants along riparian zone in Shennongjia Area

Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid their attentions to riparian zone and had been aware of the important effects of riparian zone in basic study and practical management. In this study, 42 sampling belts (10 m?00 m) parallel to the bank of Xiangxi River at different elevations in Shennongjia Area were selected to investigate the riparian vegetation and rare plants. 14 species of rare plants were found distributing in riparian zone, accounting for 42.4% of the total rare plant species in Shennongjia Area. The main distribution range of the 14 rare plant species was the evergreen and deciduous mixed broadleaved forest at elevation of 1200-1800 m, where, species diversity of plant community was the maximum at the moderate elevation. The analysis of TWINSPAN divided the 14 rare species into 3 groups against the elevation, namely low elevation species group, moderate elevation species group, and high elevation species group. The analysis of DCA ordination showed similar results to that of TWINSPAN. In the paper, the authors discussed the reasons forming the distribution pattern of rare plant species, and pointed out that the important function of riparian zone on rare plant species protection.

Optimized Strategy for Layout of Crop Production Areas in Hunan Province

The optimized strategy made a comprehensive consideration of resources, technology, market orientation, production scale, industry basis and layout based on the principle of crop security and farmers’ income increasing, and determined the general planning on layout and structure optimization of future crop production ar-eas, with present crop production, market outlook, future industry development, con-cluding crop production characteristics of the 4 crop regions, and proposing function orientation and highlights.

Performance analysis of IEEE 802.11e EDCA in wireless LANs

In this paper, we propose an analytical model for the performance evaluation of IEEE 802.1 le enhanced distributed channel access （EDCA）. Different from most previous analytical studies based on the saturation assumption, we extend the analytical model to non-saturation conditions. An empty state is introduced into the Markov chain to represent the status of transmission queue being empty. This model can be used to calculate the traffic priority, throughput, and MAC layer delay with various configurations of contention parameters. A detailed simulation is provided to validate the proposed model. With the help of this model, the contention parameters can be configured appropriately to achieve specific quality-of-service （QoS） requirements.

Optimizing the Layout of Rectangular Hull Tiles

Rectangular tiles can be laid on a ship's hull for protection, but the sides of the tiles must be adjusted so adjacent tiles will conform to the curvature of the hull.A method for laying tiles along a reference line was proposed, and an allowable range of displacement for the four vertices of the tile was determined.Deformations of each tile on a specific reference line were then obtained.It was found that the least deformation was required when the tiles were laid parallel to a line with the least curvature.After calculating the mean curvature on the surface, the surface was divided into three layout areas.A set of discrete points following the least deformation of the principal curvatures was obtained.A NURBS interpolation curve was then plotted as the reference line for laying tiles.The optimum size of the tiles was obtained, given the allowable maximum deformation condition.This minimized the number of bolts and the amount of stuffing.A typical aft hull section was selected and divided into three layout areas based on the distribution of curvature.The optimum sizes of rectangular tiles were obtained for every layout area and they were then laid on the surface.In this way the layout of the rectangular tiles could be plotted.

Spatial and Temporal Patterns of Soil Nitrogen Distribution under Different Land Uses in a Watershed in the Hilly Area of Purple Soil,China

Quantification of soil spatial and temporal variability at watershed scale is important in ecological modeling, precision agriculture, and natural resources management. The spatio-temporal variations of soil nitrogen under different land uses in a small watershed （12.10 km^2） in the hilly area of purple soil at the upper reaches of the Yangtze River in southwestern China were investigated by using conventional statistics, geostatistics, and a geographical information system in order to provide information for land management and control of environmental issues. A total of 552 soil samples （o to 15 cm） from 276 sites within the watershed were collected in April and August of 2o11, and analyzed for soil total nitrogen （STN） and nitrate nitrogen （NO3-N）. We compared spatial variations of STN and NO3-N under different land uses as well as the temporal variations in April （dry season） and August （rainy season）. Results showed that STN contents were deeply affected by land-use types; median STN values ranged from 0.94to 1.27g.kg-I, and STN contents decreased in the following order： paddy field 〉 foresfland 〉 sloping cropland. No significant difference was found for STN contents between April and August under the same land use. However, NO3- N contents were 23.26, 10.58, and 26.19 mg·kg^-1 in April, and 1.34, 8.51, and 3.00 mg·kg^-1 in August for the paddy field, sloping cropland and forestland, respectively. Nugget ratios for STN indicatedmoderate spatial dependence in the paddy field and sloping cropland, and a strong spatial dependence in forestland. The processes of nitrogen movement, transformation, absorption of plant were deeply influenced by land use types; as a result, great changes of soil nitrogen levels at spatial and temporal scales were demonstrated in the studied watershed.

China＇s Service Economy in the Coming Five Years （2011-2015）

This paper suggests that a new approach should be taken for the development of China＇s service sector. Priorities for this include： appropriate objectives for service sector development, enhanced functionality, integrated development between manufacturing and services, improved regional layout of the service sector, and the emergence of reputable brands and leading enterprises. Well-designed and effective industrial policies, as well as calls for major breakthroughs in institutional mechanisms, must support the development of the service sector. Additionally, excessive burdens and difficult financing channels need to be addressed. More attention should be paid to the construction of the credit system, service standardization, and service statistical accounting as element tasks.

Regional Distribution and Sustainable Development Strategy of Mineral Resources in China

This paper summarizes the distribution and production layout of the major mineral resources in China,including coal,iron ore,copper and bauxite,from a national perspective.It also identifies the incompatibility between the mineral resources distribution and regional economic development.Significant issues with China's mineral resource industry cause challenges for the sustainable development of both the mining industry and the national socio-economy.The sustainability of regional mineral resources and the environmental pollution by mining in the western China were also analyzed.Results show that the distribution of China's mineral resources is misaligned with its regional layout of economic development.China's mineral resources have been over-exploited,and the mineral resources production in the eastern China is unsustainable.The continuously expanding production of mineral resources in the western China has heavily endangered the ecological environment.We propose strategies to boost the sustainable development of mineral resources,including measures to accelerate economic development and enhance the sustainability of domestic mineral resources.We also offer suggestions for scientifically planning the mineral resource prospecting and exploitation and regional economic layout,as well as for proactively undertaking industry transfer in the eastern China and raising the environmental benchmark requirements for the mineral industry in the central and western China.

Distribution patterns of benthic diatoms during summer in the Niyang River,Tibet,China

The aim of this study was to investigate the distribution, density, community structure and biodiversity characteristics of benthic diatoms, and to analyze whether differences in species composition and abundance exist in different regions of the Niyang River, Tibet. Among the 157 taxa observed in 15 sampling sites in the main river and tributary, most were casual species （〉100）, the relative abundance of the genera Achnantkes and Fragilaria was 67% of the total relative abundance. Acknantkes minutissima was the most important species and dominated the whole river reaches （average relative abundance was 30%）; the average diatom densities were 7.4 x 105 cell/cm2 at all sites, and increased slowly from the upper section to downriver. The significant indicator taxa with higher relative abundance were Achnanthes biasolettiana （18.0%） and Fragilaria arcus （18.2%）, Fragilaria capucina var. vaucheriae （31.2%）, Fragilaria construens var. renter （11.3%） and Cymbella affinis （11.0%） in the upper, tributary and mid-river sections, respectively. Achnanthes minutissima was the most abundant species （56%） in the downriver section. Biodiversity indices showed a gradual decrease from the up- to down-river section, and dominant species were more abundant in the upper and mid-river sections than in the downriver section. A two-way indictor species analysis （TWINSPAN） of diatom composition clearly showed four different groups, namely the upper, mid, lower and tributary sections. Detrended correspondence analysis （DCA） supported the results of TW1NSPAN, and the characteristics of site distribution and species composition in the Niyang River supported the spatial structure of diatom assemblages. This study indicates that bio-assessment programs utilizing benthic diatoms could clearly benefit lotic water with regional stratification.

Bi-level hybrid local search approach for three-dimensional loading problem with balancing constraints

This paper presents a bi-level hybrid local search(BHLS)algorithm for the three-dimensional loading problem with balancing constraints(3DLP-B),where several rectangular boxes with even densities but different sizes are loaded into a single cubic bin to meet the requirements of the space or capacity utilization and the balance of the center of gravity.The proposed algorithm hybridizes a novel framed-layout procedure in which the concept of the core block and its generation strategy are introduced.Once the block-loading sequence has been determined,we can load one block at a time by the designed construction heuristic.Then,the double-search is introduced;its external search procedure generates a list of compact packing patterns while its internal search procedure is used to search the core-block frames and their best distribution locations.The approach is extensively tested on weakly to strongly heterogeneous benchmark data.The results show that it has better performance in improving space utilization rate and balanced condition of the placement than existed techniques:the overall averages from 79.85%to 86.45%were obtained for the balanced cases and relatively high space-usage rate of 89.44%was achieved for the unbalanced ones.

Robot SLAM with Ad hoc wireless network adapted to search and rescue environments

An innovative multi-robot simultaneous localization and mapping(SLAM)is proposed based on a mobile Ad hoc local wireless sensor network(Ad-WSN).Multiple followed-robots equipped with the wireless link RS232/485module act as mobile nodes,with various on-board sensors,Tp-link wireless local area network cards,and Tp-link wireless routers.The master robot with embedded industrial PC and a complete robot control system autonomously performs the SLAM task by exchanging information with multiple followed-robots by using this self-organizing mobile wireless network.The PC on the remote console can monitor multi-robot SLAM on-site and provide direct motion control of the robots.This mobile Ad-WSN complements an environment devoid of usual GPS signals for the robots performing SLAM task in search and rescue environments.In post-disaster areas,the network is usually absent or variable and the site scene is cluttered with obstacles.To adapt to such harsh situations,the proposed self-organizing mobile Ad-WSN enables robots to complete the SLAM process while improving the performances of object of interest identification and exploration area coverage.The information of localization and mapping can communicate freely among multiple robots and remote PC control center via this mobile Ad-WSN.Therefore,the autonomous master robot runs SLAM algorithms while exchanging information with multiple followed-robots and with the remote PC control center via this local WSN environment.Simulations and experiments validate the improved performances of the exploration area coverage,object marked,and loop closure,which are adapted to search and rescue post-disaster cluttered environments.

Drought over China in the 21st Century: Results of RegCM3

Based on 150-year simulations of a regional climate model, RegCM3, under the Special Report on Emissions Scenarios (SRES) A1B scenario, the effective drought index (EDI) is used to project the future drought change in China. During the baseline period 1986-2005, RegCM3 was found to reliably simulate the spatial pattern of drought over the country. Over the 21st century, the regionally averaged EDI should increase, corresponding to a decrease of drought, while the probability of extreme drought events should increase. Geographically, drought should clearly increase in Northeast China, the middle and lower reaches of the Yangtze River valley, Southwest China, and southern Tibet but decrease in most parts of the rest of the country.

Achieving Efficient Channel Utilization for Data Communications in IEEE 802.11 WLAN

In the IEEE g02. 11 protocol, the adoption of the exponential backoff technique leads to throughput performance strongly dependent on the initial contention window size and, most importantly, on the number of contending stations considered in the network. This paper proposes a simple but accurate method to dynamically estimate the number of contending stations in a wireless local area network （ WLAN ）. Based on estimation, all the mobile stations dynamically adjust the initial contention window in medium access control （ MAC ） layer to avoid collisions. The simulation results show that the proposed algorithm can achieve efficient channel utilization, higher system throughput, and better fairness performance.

Performance Analysis of WLAN Medium Access Control Protocols in Simulcast Radio-Over-Fiber-Based Distributed Antenna Systems

The performance of three wireless local-area network(WLAN) media access control(MAC) protocols is investigated and compared in the context of simulcast radioover-fiber-based distributed antenna systems(RoF-DASs) where multiple remote antenna units(RAUs) are connected to one access point(AP) with different-length fiber links.The three WLAN MAC protocols under investigation are distributed coordination function(DCF) in basic access mode,DCF in request/clear to send(RTS/CTS) exchange mode,and point coordination function(PCF).In the analysis,the inter-RAU hidden nodes problems and fiber-length difference effect are both taken into account.Results show that adaptive PCF mechanism has better throughput performances than the other two DCF modes,especially when the inserted fiber length is short.

Temporal and Spatial Distribution Patterns of Grain Crops in the West Liaohe River Basin

Here,we quantitatively determine temporal and spatial distribution characteristics of main grain crops in the West Liaohe River basin,Inner Mongolia,China,from 2000 to 2010 based on MODIS remote sensing data and NDVI time series information for the years 2000,2005 and 2010.Phenological calendars and a decisionmaking tree extraction model were also used to obtain spatial distribution information of spring maize,spring wheat and soybean.We found that in 2010,the sown area of the main grain crops in the West Liaohe River basin was 11 965.08km2,of which,the sown area for spring maize accounted for 92.28%and was concentrated in the lower reaches of the region.Spring wheat accounted for 3.14% and was mainly in the middle reaches.Soybean accounted for 4.58% and was predominantly in the upper reaches.From 2000 to 2005,the sown area of these grain crops in the West Liaohe River basin grew by 29.77%,mainly in the lower reaches： spring maize grew by 38.99%,spring wheat by 39.04% and soybean by 21.27%.From 2005 to 2010,growth in the sown area of these crops was slow（5.18% growth） and mainly in the lower reaches of the basin.The sown area of spring maize increased,but decreased for both spring wheat and soybean.

Land Cover Status in the Koshi River Basin,Central Himalayas

The Koshi River Basin is in the middle of the Himalayas,a tributary of the Ganges River and a very important cross-border watershed.Across the basin there are large changes in altitude,habitat complexity,ecosystem integrity,land cover diversity and regional difference and this area is sensitive to global climate change.Based on Landsat TM images,vegetation mapping,field investigations and 3S technology,we compiled high-precision land cover data for the Koshi River Basin and analyzed current land cover characteristics.We found that from source to downstream,land cover in the Koshi River Basin in 2010 was composed of water body（glacier）,bare land,sparse vegetation,grassland,wetland,shrubland,forest,cropland,water body（river or lake） and built-up areas.Among them,grassland,forest,bare land and cropland are the main types,accounting for 25.83%,21.19%,19.31% and 15.09% of the basin＇s area respectively.The composition and structure of the Koshi River Basin land cover types are different between southern and northern slopes.The north slope is dominated by grassland,bare land and glacier;forest,bare land and glacier are mainly found on northern slopes.Northern slopes contain nearly seven times more grassland than southern slopes;while 97.13% of forest is located on southern slopes.Grassland area on northern slope is 6.67 times than on southern slope.The vertical distribution of major land cover types has obvious zonal characteristics.Land cover types from low to high altitudes are cropland,forest,Shrubland and mixed cropland,grassland,sparse vegetation,bare land and water bodies.These results provide a scientific basis for the study of land use and cover change in a critical region and will inform ecosystem protection,sustainability and management in this and other alpine transboundary basins.