Statistical Model on the Time and Time Difference Error of Arrival in TDOA Location Estimation

Additional time delay of arrival resulted from non-line of sight(NLOS)propagation and muti-path effect in(cellular) environment is the dominant factor resulting in TDOA location error,study on the statistical property of TDOA error is useful for improving the accuracy of TDOA location.Based on the exponential distribution property of NLOS propagation delay,and considering the system error resulted from the signal detection,the authors establish a statistical model of arrival time and a model of TDOA error distribution by statistics when non-light of sight and multi-path propagation exist.The models reflect the statistical property of arrival time and TDOA error in cell network,the simulation shows that the proposed models have a good accuracy and a satisfactory behavior.     

不同密度对棉花根系生长与分布的影响

 利用根钻挖掘法研究了大田条件下6个种植密度对棉花根系生长分布的影响。结果表明：1.5万～8.7万株·hm^-2密度水平根干物质质量密度、根长密度在吐絮之前持续增加,而10.5万株·hm^-2处理在盛铃期后出现下降。在盛蕾期至初花期,棉花根干物质质量密度、根长密度均随种植密度的增加而增大;在盛花期至吐絮初期,根干物质质量密度以3.3万株·hm-2处理最高,3.3万～10.5万株·hm^-2处理根长密度显著高于1.5万株·hm^-2。根系垂直分布结果表明,0～30 cm土层内的根干物质质量和根长分别占所测土体中根量的67.80%～97.44%和54.01%～93.33%。低密度处理（1.5万株·hm^-2、3.3万株·hm^-2）的浅层（0～20 cm）根干物质质量密度和根长密度在盛蕾期均低于其它处理,深层（30～60 cm）根干物质质量密度和根长密度在初花期至盛铃期低于其它处理。吐絮初期,各密度处理根长密度在深层土壤有显著差异。     

微灌毛管水力学研究——微灌水力设计计算方法探讨之一

本文不采用缝隙管的假定,提出毛管水头线的多段折线模型;在此基础上,定义了降比r和压比G,根据r的大小,讨论了均匀坡毛管压力水头的分布;讨论了总水头损失计算方法;导出诸水力特征量的计算公式。     

发菜生存与生长分布的微生态环境

通过野外调查 ,研究和分析了对发菜生存与生长发育起直接作用的微土壤、微气候、微地形、微植被和风向等微生态环境。发菜对生存环境的选择性很强。其中 ,干一湿交替的微气候环境是一个起决定作用的关键性因子 ,是发菜生存和生长发育的必要条件。一方面 ,发菜藻体在干燥的状态下 ,有利于干物质的积累 ,是发菜生存和生长的必要前提 ;另一方面 ,发菜藻体只有在一定湿润状态下 ,才能生长发育。由于干旱气候环境所限 ,野生发菜的生长速度极为缓慢。     

山西省冬小麦生产潜力时空分布与气象因子分析

估算一定区域内作物生产潜力,对于明确该区域作物生产力及其限制因子具有重要意义。采用农业生态区域法和生产潜力递减机制法估算山西省冬小麦生产潜力,并解析其与主要气象因子的关系。结果表明,2004-2013年山西省冬小麦平均光合、光温、气候和土地生产潜力分别介于63.63~74.81、10.86~12.97、3.68~5.65和2.71~4.73t/hm ²。山西冬小麦生产潜力分布特征为南部普遍低于中部地区,中部盆地地区普遍低于东西部高海拔地区。与2004-2008年相比,2009-2013年晋中西部地区和吕梁冬小麦光合和光温生产潜力有所增加,而晋中东部和长治东部的冬小麦气候和土地生产潜力有所降低。限制冬小麦气候和土地生产潜力的主要气象因子是生育期降水量和日平均温度。     

近55 a内蒙古极端降水指数时空变化特征

基于内蒙古100个气象站点1960-2014年日降水数据,选取气候变化监测与指数专家组(ETCCDI)推荐的9个极端降水指数,采用Sen’s斜率法和Mann-Kendall非参数统计检验方法以及空间地统计方法,研究了极端降水指数时空演变特征。结果表明:研究区区域平均的全部极端降水指数均呈不同程度的下降趋势,且年际波动显著;分区的年际趋势有所差异,即东部地区潮湿日数(NW)呈增加趋势,其余极端降水指数均呈减少趋势,其中持续干燥指数(CDD)呈显著下降趋势(P<0.05);中部地区所有极端降水指数均呈减少趋势,其中年总降水量(PRCPTOT)减少趋势较明显;西部地区持续湿润指数(CWD)、强降水量(R95)、单日最大降水量(Rx1day)、5日最大降水量(Rx5day)呈减少趋势,其余指数均呈增加趋势。从极端降水指数变化趋势的空间分布特征来看,区域差异显著,总体上呈下降趋势的站点主要分布于内蒙古东部和中部地区,而呈上升趋势的站点主要分布于内蒙古东北部和西部地区。     

Molecular cloning and expression of kidney‐type glutaminase from common carp (Cyprinus carpio) and its up‐regulation by glutamine in primary culture enterocyte

Glutaminase (GLS) is the key enzyme of glutamine (Gln) metabolism and utilization. In this study, a cDNA encoding GLS protein was identified from common carp Cyprinus carpio intestine. The open reading frame of GLS cDNA encodes a polypeptide of 595 amino acids, which shows a high similarity with its zebrafish Danio rerio counterpart. Bioinformatic analysis showed the protein belongs to kidney‐type GLS. The putative protein has glutaminase domain and ankyrin repeats domain, which are highly conserved among vertebrate orthologues. Real‐time quantitative PCR analysis revealed that the abundance of GLS mRNA was the highest in the white muscle, followed by the brain, eyeball and pituitary. Glutaminase was ubiquitously expressed in all intestinal segments of common carp. The activity of GLS did not distribute uniformly along the entire length of the intestine. In primary culture enterocyte, and the expression of GLS mRNA is up‐regulated quickly and effectively by Gln.     

Vertical distribution of larval Atlantic menhaden (Brevoortia tyrannus) and Atlantic croaker (Micropogonias undulatus): Implications for vertical migratory behaviour and transport

Understanding the interactions among biological and physical processes is essential to determining how the environment affects transport and survival of fishes. We examined vertical distribution in larval Atlantic menhaden (Brevoortia tyrannus) and Atlantic croaker (Micropogonias undulatus) using 126 depth stratified tows in Delaware Bay, USA, during two cruises, in December 2007 and February 2008. Menhaden larvae were 16.8–24.6 and 20.5–26.2 mm standard length in December and February. Corresponding lengths for croaker were 9.3–17.9 and 8.6–19.6 mm. Using empirical observations, and statistically derived models, we explored larval concentration for both species as a function of location, depth, diel period, tidal period, size, and pairwise interactions. Menhaden concentration was best modeled as a function of station, cruise, and interactions between depth and size as well as between station and cruise. No significant differences in larval menhaden concentration were present among tidal and diel periods. Croaker concentration was best modeled as a function of size and interactions between station and diel period, depth and size, cruise and size. Despite tidal period not emerging as a significant model parameter, we observed larger croaker larvae during nighttime flood tides. Our statistical models are consistent with processes of up‐estuary transport for both species, suggesting larvae are increasingly affected by behavioral responses as larvae grow, exhibiting stronger patterns in vertical distribution. The results refine our understanding of the potential importance of size‐related differences in vertical distribution for larval transport in these species. Future research should examine the interactions among size‐specific vertical migratory capabilities, vertical distribution, transport, and retention.     

Spatial distribution of Antarctic minke whales (Balaenoptera bonaerensis) in relation to spatial distributions of krill in the Ross Sea,Antarctica

The spatial distribution of Antarctic minke whales in the Ross Sea with relation to spatial distributions of their prey – krill – was investigated in this study using generalized additive models (GAMs). Spatial distributions of two species of krill (ice and Antarctic krill) were estimated by GAMs. Three abiotic factors – distance from the continental shelf break (800 m isobaths), the mean temperature and salinity from the surface to 200 m (MTEM‐200 and MSAL‐200), and latitude and longitude – were used as covariates for models of krill. Estimated spatial distributions of krill were then used with other covariates to model the spatial distribution of Antarctic minke whales. In the selected model of Antarctic minke whales, Antarctic krill were more influential than ice krill. The number of Antarctic minke whales increased as the density of Antarctic krill increased to around 1.5 g m^?2. Beyond that, the number of Antarctic minke whales decreased as the density of Antarctic krill increased. High densities of the Antarctic minke whales were estimated along the sea ice edge in the eastern part of the Ross Sea. Specifically, the densities were high in the north of the continental shelf break where low MTEM‐200 and MSAL‐200 and intermediate densities of Antarctic krill were observed. Further data collection is needed to investigate interannual variations and trends in their relationship. The results show that the spatial distribution of Antarctic minke whales is a function of longitude, distance from the shelf break, oceanographic condition (temperature and salinity), and densities of ice and Antarctic krill.     

赣县长防林工程生态效益调查

通过一系列的调查、统计及数据分析,其结果证明了赣县在长防林工程实施后森林资源显著增长,水土流失大幅度减少,生态环境不断改善.