分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
摘要： In most arid and semi-arid regions of the world, domestic livestock and native wildlife share pastures, and their competition for forage and habitat is thought to be a serious conservation issue. Moreover, unmanaged grazing by livestock can cause the population decline in wild ungulates. The diet of an animal species is a determining aspect of its ecological niche, and investigating its diet has been one of the initial steps in basic ecology study of a new species. To get an approximate understanding of the interspecific food relationships of argali (Ovis ammon darwini) between sexes, and sympatric domestic sheep and goats, we compared the diet compositions and diet-overlaps among these herbivores, i.e., male argali, female argali, domestic sheep, and domestic goats in the Mengluoke Mountains of Xinjiang, China by using micro-histological fecal analysis. Female argali, male argali, domestic sheep and domestic goat primarily consumed forbs (43.31%±4.86%), grass (36.02%±9.32%), forbs (41.01%±9.18%), and forbs (36.22%±10.61%), respectively in warm season. All these animals consumed mostly shrubs (female argali: 36.47%±7.56%; male argali: 47.28%±10.75%; domestic sheep: 40.46%±9.56%; and domestic goats: 42.88%±9.34%, respectively) in cold season. The diet-overlaps were relatively high among all species in cold season with values ranging from 0.88 to 0.94. Furthermore, Schoener’s index measured between each possible pair of 4 herbivores increased from the warm season to the cold season. The results illustrate that the high degree of diet-overlap of argali and domestic livestock (sheep and goat) may pose a threat to the survival of the argali in cold season. From the viewpoint of rangeland management and conservation of the endangered argali, the numbers of domestic sheep and goats should be limited in cold season to reduce food competition.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
RAJAEI, Fatemeh
SARI, Abbas E
SALMANMAHINY, Abdolrassoul
RANDHIR, Timothy O
DELAVAR, Majid
BEHROOZ, Reza D
BAVANI, Alireza M
摘要： Conversion of forest land to farmland in the Hyrcanian forest of northern Iran increases the nutrient input, especially the phosphorus (P) nutrient, thus impacting the water quality. Modeling the effect of forest loss on surface water quality provides valuable information for forest management. This study predicts the future impacts of forest loss between 2010 and 2040 on P loading in the Tajan River watershed at the sub-watershed level. To understand drivers of the land cover, we used Land Change Modeler (LCM) combining with the Soil Water Assessment Tool (SWAT) model to simulate the impacts of land use change on P loading. We characterized priority management areas for locating comprehensive and cost-effective management practices at the sub-watershed level. Results show that agricultural expansion has led to an intense deforestation. During the future period 2010–2040, forest area is expected to decrease by 34,739 hm2. And the areas of pasture and agriculture are expected to increase by 7668 and 27,071 hm2, respectively. In most sub-watersheds, P pollution will be intensified with the increase in deforestation by the year 2040. And the P concentration is expected to increase from 0.08 to 2.30 mg/L in all of sub-watersheds by the year 2040. It should be noted that the phosphorous concentration exceeds the American Public Health Association′s water quality standard of 0.2 mg/L for P in drinking water in both current and future scenarios in the Tajan River watershed. Only 30% of sub-watersheds will comply with the water quality standards by the year 2040. The finding of the present study highlights the importance of conserving forest area to maintain a stable water quality.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
BOZOROV, Tohir A
USMANOV, Rustam M
YANG, Honglan
HAMDULLAEV, Shukhrat A
MUSAYEV, Sardorbek
SHAVKIEV, Jaloliddin
NABIEV, Saidgani
ZHANG, Daoyuan
ABDULLAEV, Alisher A
摘要： Drought is a common abiotic stress that considerably limits crop production. The objective of this study is to explore the influence of water deficiency on the yield, physiologic and metabolomic attributes in upland cotton cultivars (Gossypium hirsutum L). Cotton cultivars, 'Ishonch' and 'Tashkent-6' were selected to study the relationships among their physiologic, metabolomic and yield attributes during water deficiency. Deficit irrigation was designed by modifying the traditional watering protocol to reduce water use. Results indicate that cotton cultivars respond differently to water deficit stress. Water deficit significantly influenced plant height, the number of internodes, and sympodial branches in both cultivars. However, yield components such as the number of bolls, boll seed, lint mass, and individual plant yield were significantly reduced only in 'Tashkent-6'. The leaf area decreased and the specific leaf weight increased in 'Ishonch' under deficit irrigation conditions. However, 'Tashkent-6' demonstrated significant water loss compared to 'Ishonch', and both cultivars showed reduced transpiration rates. Untargeted metabolite profiles of leaves showed clear separation in 'Ishonch', but not in 'Tashkent-6' under deficit irrigation compared to full irrigation. The individual metabolites such as proline and galactinol showed strong association with yield under water deficit stress. Moreover, this study indicates that leaf area and transpiration intensity influence yield during water deficiency. In summary, the correlation among morpho-physiologic, metabolic, and yield components significantly varied between the two cultivars under water deficiency. The flowering stage was sensitive to water stress for both cultivars. The direct relationship between physiology, metabolism, and yield may be a useful selection criterion for determining candidate parents for cotton drought tolerance breeding.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
LI, Congjuan
LIU, Ran
WANG, Shijie
SUN, Yongqiang
LI, Shengyu
ZHANG, Heng
GAO, Jie
DANG, Yanxi
ZHANG, Lili
摘要： Extremely saline soils are very harsh environments for the growth and survival of most plant species, however, halophytes can grow well. The underlying mechanism of halophyte to resist high saline is not well understood by us. This study was conducted at the potash mine near the Lop Nur, China, where the effects of the halophyte Suaeda salsa L. on the saline-alkaline soils and its growth and sustainability were investigated. Four plots (in which the salt encrustation layers were removed), with different soil treatments were evaluated: (1) undisturbed soil, with no additional treatment (T1); (2) the slag soil zone, in which a 40-cm layer of slag was placed on the undisturbed soil surface (T2); (3) slag+sandy soil, in which a 20-cm layer of slag was placed in the lower layer and 20 cm of sandy soil, taken from an area about 70 km away from Lop Nur potash mine, where Tamarix species were growing, was placed in the upper layer (T3); and (4) a 40-cm sandy soil layer taken from the area where Tamarix species were growing was placed on undisturbed soil (T4). Soil nutrient contents increased in the four treatments, but salt content only decreased in the T1 treatment. Salt content in the T4 treatment increased over the two-year period, which may be partly attributed to salt deposition from wind-blown dust within the mine and salt accumulation within the surface soil (0–20 cm) in response to high evaporative demands. The S. salsa plants exhibited greater improvements in growth under the T4 treatment than under the T1, T2, and T3 treatments, which demonstrated that low levels of salinity are beneficial for the growth of this species. The T1 treatment was sustainable because of its low cost and superior soil improvement characteristics. Therefore, S. salsa plants not only reduced soil salinity and increased soil nutrient levels, but also ameliorated the plant growth environment, which would be beneficial for both the ecological restoration of the Lop Nur area and similar areas throughout the world.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
摘要： Grazing exclusion is one of the most efficient approaches to restore degraded grassland but may negatively affects the recovery of species diversity. Changes in plant species diversity should be a consequence of the ecological assembly process. Local community assembly is influenced by environmental filtering, biotic interactions, and dispersal. However, how these factors potentially contribute to changes to species diversity is poorly understood, especially in harsh environments. In this study, two management sites within a Stipa breviflora desert steppe community (typical natural steppe) were selected in northern China. In one of the two management sites, grazing has been excluded since 2010 and in the other with open grazing by sheep. In August 2016, three plots were established and 100 sampling units were created within each plot in a 5 m×5 m area at the two management sites. To assess the effects of grazing exclusion on S. breviflora steppe, we analyzed the vegetation biomass, species diversity, soil organic carbon, and soil particle size distribution using paired T-tests. In addition, variation partitioning was applied to determine the relative importance of environmental filtering and dispersal limitation. Null mode analysis was used to quantify the influence of biotic interactions in conjunction with EcoSim niche overlap and co-occurrence values. Our results demonstrated that (1) species diversity significantly decreased and the main improvements in soil quality occurred in the topsoil 0–10 cm after the grazing exclusion; (2) environmental filtering was important for community assembly between grazed and fenced grassland and this appears particularly true for soil particle size distribution, which may be well correlated with soil hydrological processes; and (3) however, competitive exclusion may play a significant role within the exclusion. The multiple pathways of assembly may collectively determine negative effects on the restoration of species diversity. Therefore, designers should be aware of the risk of reducing grazing exclusion-induced species diversity and account for manipulating processes. This in turn will reduce dominant species and promote environmental heterogeneity to maximize species diversity in semi-arid regions.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
摘要： Precipitation, a natural feature of weather systems in the Earth, is vitally important for the environment of any region. Under global climate change condition, the characteristics of precipitation have changed as a consequence of enhanced global hydrological cycle. The source region of the Yellow River (SRYR), locating within the Qinghai-Tibet Plateau, is sensitive to the global climate change due to its complex orography and fragile ecosystem. To understand the precipitation characteristics and its impacts on the environment in the region, we studied the characteristics of rainy days and precipitation amount of different precipitation classes, such as light (0–5 and 5–10 mm), moderate (10–15, 15–20 and 20–25 mm) and heavy (≥25 mm) rains by analyzing the precipitation data of typical meteorological stations in the SRYR during the period 1961–2014, as well as the trends of persistent rainfall events and drought events. Results showed that annual average precipitation in this area had a non-significant (P>0.05) increasing trend, and 82.5% of the precipitation occurred from May to September. Rainy days of the 0–5 mm precipitation class significantly decreased, whereas the rainy days of 5–10, 10–15, and 20–25 mm precipitation classes increased and that of ≥25 mm precipitation class decreased insignificantly. The persistent rainfall events of 1- or 2-day and more than 2-day showed an increasing trend, with the 1- or 2-day events being more frequent. Meanwhile, the number of short drought periods (≤10 days) increased while long drought periods (>10 days) decreased. Since the 0–5 mm precipitation class had a huge impact on the grasslands productivity; the 5–10, 10–15, and 20–25 mm precipitation classes had positive effects on vegetation which rely on the deep soil water through moving nutrients and water into the root zone of these vegetation or through the plant-microbe interactions; the ≥25 mm precipitation class contributed to the floods; and more persistent rainfall events and fewer long drought events inferred positive effects on agriculture. Thus, these results indicate grassland degradation, less risk of floods, and the upgrading impact of climate change on agriculture. This study may provide scientific knowledge for policymakers to sustain the eco-environmental resources in the SYSR.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
摘要： The variation in soil organic carbon density (SOCD) has been widely documented at various spatial and temporal scales. However, an accurate method for examining the attribution of explanatory factors for change in SOCD is still lacking. This study aims to attribute and quantify the key climatic factors, anthropogenic activities, and soil properties associated with SOCD change in the native grasslands of Inner Mongolia, China, by comparing data between the 1960s and the 2010s. In 2007 and 2011, we resampled 142 soil profiles which were originally sampled during 1963–1964 in the native grasslands of Inner Mongolia. SOCD was determined in A horizon (eluvial horizon) of the soil. We selected the explanatory factors based on a random forest method, and explored the relationships between SOCD change and each of the explanatory factors using a linear mixed model. Our results indicated that the change in SOCD varied from the east to the west of Inner Mongolia, and SOCD was 18% lower in the 2010s than in the 1960s. The lower SOCD in the 2010s may primarily be attributed to the increasing in mean annual water surface evaporation, which explained approximately 10% and 50% of the total variation and explainable variation in the change in SOCD, respectively. The sand content of the soil is also a significant explanatory factor for the decrease in SOCD, which explained about 4% and 21% of the total variation and explainable variation in the change in SOCD, respectively. Furthermore, the collection of quantitative information on grazing frequency and duration may also help to improve our understanding of the anthropogenic factors that govern the change in SOCD.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
摘要： The main purpose of this study was to explore the dynamic changes of greenhouse gas (GHG) from grasslands under different degradation levels during the growing seasons of Inner Mongolia, China. Grassland degradation is associated with the dynamics of GHG fluxes, e.g., CO2, CH4 and N2O fluxes. As one of the global ecological environmental problems, grassland degradation has changed the vegetation productivity as well as the accumulation and decomposition rates of soil organic matter and thus will influence the carbon and nitrogen cycles of ecosystems, which will affect the GHG fluxes between grassland ecosystems and the atmosphere. Therefore, it is necessary to explore how the exchanges of CO2, CH4 and N2O fluxes between soil and atmosphere are influenced by the grassland degradation. We measured the fluxes of CO2, CH4 and N2O in lightly degraded, moderately degraded and severely degraded grasslands in Inner Mongolia of China during the growing seasons from July to September in 2013 and 2014. The typical semi-arid grassland of Inner Mongolia plays a role as the source of atmospheric CO2 and N2O and the sink for CH4. Compared with CO2 fluxes, N2O and CH4 fluxes were relatively low. The exchange of CO2, N2O and CH4 fluxes between the grassland soil and the atmosphere may exclusively depend on the net exchange rate of CO2 in semi-arid grasslands. The greenhouse gases showed a clear seasonal pattern, with the CO2 fluxes of –33.63–386.36 mg/(m•h), CH4 uptake fluxes of 0.113–0.023 mg/(m•h) and N2O fluxes of –1.68–19.90 µg/(m•h). Grassland degradation significantly influenced CH4 uptake but had no significant influence on CO2 and N2O emissions. Soil moisture and temperature were positively correlated with CO2 emissions but had no significant effect on N2O fluxes. Soil moisture may be the primary driving factor for CH4 uptake. The research results can be in help to better understand the impact of grassland degradation on the ecological environment.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
摘要： Knowledge about the effects of vegetation types on soil properties and on water dynamics in the soil profile is critical for revegetation strategies in water-scarce regions, especially the choice of vegetation type and human management measures. We focused on the analysis of the effects of vegetation type on soil hydrological properties and soil moisture variation in the 0–400 cm soil layer based on a long-term (2004―2016) experimental data in the northern Loess Plateau region, China. Soil bulk density (BD), saturated soil hydraulic conductivity (Ks), field capacity (FC) and soil organic carbon (SOC) in 2016, as well as the volumetric soil moisture content during 2004–2016, were measured in four vegetation types, i.e., shrubland (korshinsk peashrub), artificial grassland (alfalfa), fallow land and cropland (millet or potato). Compared with cropland, revegetation with peashrub and alfalfa significantly decreased BD and increased Ks, FC, and SOC in the 0–40 cm soil layer, and fallow land significantly increased FC and SOC in the 0–10 cm soil layer. Soil water storage (SWS) significantly declined in shrubland and grassland in the 40–400 cm soil layer, causing severe soil drought in the deep soil layers. The study suggested that converting cropland to grassland (alfalfa) and shrubland (peashrub) improved soil-hydrological properties, but worsened water conditions in the deep soil profile. However, natural restoration did not intensify deep-soil drying. The results imply that natural restoration could be better than revegetation with peashrub and alfalfa in terms of good soil hydrological processes in the semi-arid Loess Plateau region.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2018-04-24 合作期刊: 《干旱区科学》
摘要： The rapid desertification of grasslands in Inner Mongolia of China poses a significant ecological threaten to northern China. The combined effects of anthropogenic disturbances (e.g., overgrazing) and biophysical processes (e.g., soil erosion) have led to vegetation degradation and the consequent acceleration of regional desertification. Thus, mitigating the accelerated wind erosion, a cause and effect of grassland desertification, is critical for the sustainable management of grasslands. Here, a combination of mobile wind tunnel experiments and wind erosion model was used to explore the effects of different levels of vegetation coverage, soil moisture and wind speed on wind erosion at different positions of a slope inside an enclosed desert steppe in the Xilamuren grassland of Inner Mongolia. The results indicated a significant spatial difference in wind erosion intensities depending on the vegetation coverage, with a strong decreasing trend from the top to the base of the slope. Increasing vegetation coverage resulted in a rapid decrease in wind erosion as explained by a power function correlation. Vegetation coverage was found to be a dominant control on wind erosion by increasing the surface roughness and by lowering the threshold wind velocity for erosion. The critical vegetation coverage required for effectively controlling wind erosion was found to be higher than 60%. Further, the wind erosion rates were negatively correlated with surface soil moisture and the mass flux in aeolian sand transport increased with increasing wind speed. We developed a mathematical model of wind erosion based on the results of an orthogonal array design. The results from the model simulation indicated that the standardized regression coefficients of the main effects of the three factors (vegetation coverage, soil moisture and wind speed) on the mass flux in aeolian sand transport were in the following order: wind speed>vegetation coverage>soil moisture. These three factors had different levels of interactive effects on the mass flux in aeolian sand transport. Our results will improve the understanding of the interactive effects of wind speed, vegetation coverage and soil moisture in controlling wind erosion in desert steppes, and will be helpful for the design of desertification control programs in future.
分类： 物理学 >> 凝聚态:电子结构、电、磁和光学性质 提交时间： 2018-04-24
摘要： 采用基于密度泛函理论的第一性原理计算方法研究了铁基超导体和铜基超导体中的电场效应。研究对象包括铁基超导体（KFe2Se2，LaFeAsO，NdFeAsO，BaFe2As2）和铜基超导体（YBa2Cu3O7，HgBa2Ca2Cu3O8，Tl2Ba2CaCu2O8，Bi2Sr2Ca2Cu3O10）。为了描述3d电子或4f电子的强关联效应，采用GGA+U方法。并采用HSE方法进一步验证了结果。给出了态密度（DOS）。给出了电场作用下体系的电荷密度的变化。发现铁基超导体中的铁离子的电子云，NdFeAsO中钕离子的电子云，铜基超导体铜离子的电子云变化明显。变化的模式更像刚体旋转而不是弹性变形。作者认为，过渡金属离子电子云的转动可能是超导电子配对的一种新媒介。在此基础上提出了一种新的超导电子配对机制。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 视网膜血管的形态和结构在眼科疾病诊断中起着非常重要的作用，同时对于心血管疾病和糖尿病的诊断也有重要作用，视网膜血管自动分割是基础。针对视网膜图像采集过程中由于疾病引起的图像光照反射过强问题，提出了一种修正的形态学与Otsu相结合的无监督视网膜血管分割算法。首先运用形态学中的高低帽变换增强血管与背景的对比度，然后提出了一种修正方法，消除部分视网膜疾病引起的光照问题，最后使用Otsu阈值方法分割血管。算法在DRIVE和STARE视网膜图像数据库中进行了测试，实验结果表明，DRIVE数据库的分割精度为0.9382，STARE数据库的分割精度为0.9460，算法的执行时间为1.6 s。算法能够精确地分割出视网膜血管，与传统的无监督视网膜血管分割算法相比，算法的分割精度高、抗干扰能力强。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 针对单一特征存在的缺陷和目标快速变化时易跟丢的问题，提出了一种结合学习率调整的自适应特征融合相关滤波跟踪算法。算法采用互补的梯度特征和颜色特征进行特征融合，通过计算滤波响应的大小来决定下一帧在融合特征中各自所占的权重，凸显优势特征，使目标与背景更具区分度。提取目标后需要更新滤波器，为了避免滤波器跟不上目标变化的情况发生，引入学习率调整机制，使滤波器更新速度能够随目标外观变化进行在线调整。因此，相较同类特征融合算法，本算法准确高效，且对于快速形变目标的鲁棒性更强。实验证明，本算法在精度和成功率上都比现有相关滤波算法更优，具有一定的应用价值。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 针对人体动作识别中传统方法在分类决策方面存在问题和缺陷，提出了一种新颖的基于深度神经网络(DNN)和遗传算法(GA)合并算法的非线性分类决策方法。首先，提出的合并算法在整个训练集合上对特征提取器进行组合，进而组合成不同的两个独立网络；再利用DNN对两个独立网络进行初始化，进一步利用GA对两个网络进行合并。然后将网络的偏差和权重表示为每层网络间的一个矩阵；最后，利用DNN对网络的偏差和权重进行训练，并在合并过程中将矩阵中的每一行当作一个染色体。实验采用了标准MNIST数据集对提出算法的性能进行评估。评估结果显示实验过程中的交叉和突变操作增加了神经元节点，提高了识别性能，并且弱化了不相关和相关神经元节点。因此，提出算法的错误率更低，网络性能更优异。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 针对医学图像数据量大、存储和传输对内存和带宽要求高的问题，提出一种基于双重压缩协议的医学图像压缩方法。首先，使用方形网络对图像进行缩小处理；然后，利用数字水印技术在缩小图像的每个像素中，嵌入该像素最佳放大方法的编码；最后，对水印图像利用JPEG-LS无损压缩，得到最终的压缩图像，并进行存储和传输。对磁共振（MR）图像和计算机断层（CT）图像两种医学图像进行实验，实验结果表明，与其他方法相比，所提方法具有明显的优势，在高压缩比的情况下，能够保留良好的图像质量。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 目标识别是实现视频监控智能分析的基础，但在光照、阴影以及杂乱背景等场景中，往往会出现目标误判以及不合理聚类等问题。针对上述问题，提出一种基于人类视觉系统（HVS）的视频监控目标提取方法，结合HVS视觉关注原理，优化背景差法检测结果中存在的重复检测和错误分割问题，并根据HVS的跟踪特点以及目标运动的连续性，结合相邻帧检测结果，达到目标区域的完整准确提取；最后，基于实际采集视频进行仿真实验，证明所提目标检测算法结果准确性更高，在复杂背景下也有良好的检测效果。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 针对推荐系统中因新项目的加入而造成的冷启动问题，在矩阵分解模型的基础上提出了融合项目图片相似度和类别属性的协同过滤推荐模型USPTMF-CFIA。首先，采用基于用户偏好和时间权重的矩阵分解模型，对评分缺失项进行预测填充；然后，利用VGG16神经网络提取项目图片特征，并结合类别属性计算新项目与历史项目的相似度，得到近邻项目；最后，根据新项目与近邻项目之间的相似度预测用户对新项目的评分，将评分高的前N个项目推荐给对应用户；通过在GroupLens提供的数据集上的实验证明，该模型的推荐准确率比MAP-BPR模型高0.006~0.015，比传统协同过滤模型高0.02~0.028，比没融合图片相似度的USPTMF-CFA模型高0.001~0.003，比ACMF模型高0.001~0.002。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 针对局部空间信息的模糊C-均值算法（WFLICM）中空间影响因子容易受到噪声影响出现错误标识的问题，提出一种融合局部和非局部空间信息的模糊C-均值聚类图像分割算法(NLWFLICM)，在WFLICM算法的模糊影响因子中引入非局部空间信息，根据噪声程度自适应地设置局部和非局部信息权重，并重新标记中心点的模糊影响因子。实验结果表明，NLWFLICM算法具有比WFLICM算法更强的鲁棒性和自适应性，并在一定程度上提高了WFLICM算法对含有大量噪声图像进行分割的鲁棒性，同时保留了图像的纹理。为了提高算法的聚类性能和收敛速度，结合Canopy算法能够快速对数据进行粗聚类的优点，提出基于Canopy聚类与非局部空间信息的FCM图像分割改进算法（Canopy-NLWFLICM），可以在NLWFLICM算法聚类前，对聚类中心进行预处理，从而提高收敛速度和图像分割精度。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 针对传统滑动窗口行人检测速度慢、无效窗口数量大和识别率低的问题，提出基于似物目标的快速行人检测算法。该算法首先使用改进的二值化赋范梯度算法生成目标候选集，再利用提出的NDOG特征描述子计算目标特征。通过在INRIA和Caltech-USA两个行人数据库分析实验，证明该算法可有效减少待检测窗口数量，提高特征表示能力，且计算时间显著降低，使用线性支持向量机作为分类器可获得较高的行人检测率。
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2018-04-24 合作期刊: 《计算机应用研究》
摘要： 针对3D模型海量点云数据存在的空间冗余问题，提出一种基于TSLVQ (tree structure lattice vector quantization)的静态点云有损渲染算法。算法旨在利用层级嵌套网格的集合，解决渲染低效的问题。首先对整个点云进行包围盒封装，多层量化，把数个较小尺度的截断包围盒嵌入到一个较高尺度的截断包围盒单元中，每一步量化过程采用八叉树方法将包围盒分割为8个最佳尺寸的空或非空小包围盒，最后在最高深度的层级里，用包围盒来代替整个小包围盒中全部的点。同时，算法可自行设定八叉树的深度，从而任意控制编码的复杂度和精度，满足渲染的实时性要求。实验结果表明，与现有的网格有损压缩算法相比，提出的算法能在保证模型重建精度的基础上，具有较好的空间分解优势，实现实时渲染效果。
点击量
点击量
下载量
评论
待评议
