牛肉部分玻璃化转变温度研究

利用调制式差示扫描量热仪(MDSC)对牛肉糜和牛肉肌动球蛋白的部分玻璃化转变温度进行了测定，得出平均转变温度约为－52.54℃。实验研究了明胶、海藻酸钠和羧甲基纤维素钠对牛肉糜部分玻璃化转变温度的影响，结果表明3种添加剂对牛肉糜部分玻璃化转变温度均无显著影响。利用程序降温仪对牛肉糜进行冻结与解冻实验，结果表明在本实验的降温速率1～5℃/min范围内，降温速率越高，所需的冻结终温越低。     

转型期中国农村土地综合整治重点领域与基本方向

该文以中国社会经济转型发展为切入点,探讨转型期中国农村土地综合整治面临的宏观背景和现实需求,进一步梳理和明确转型期中国农村土地综合整治基本方向、战略重点。结果表明,当前中国社会经济转型将进入较为剧烈、各类矛盾较为突出的关键时期,中国农村土地综合整治应立足农村、联动城乡,搭建新农村建设和城乡统筹发展新平台。以农用地整治及宜耕土地开发为先导,以农村居民点用地整治为战略重心是当前中国土地整治研究重点领域和核心内容。同时,基于农村土地整治多功能性,开展土地综合整治的多区域、多尺度社会经济、生态环境影响过程及其效应研究。把生态文明建设融入农村土地整治的全过程,以促进城乡一体化发展和适应现代农业专业化、标准化、规模化和集约化发展要求为目标,以维护农民合法权益为前提,以集中连片推进为手段,开展多目标土地综合整治是转型期中国农村土地整治的基本方向。并应加强对农村土地综合整治过程涉及的资金筹措与权益分配、资源环境效应及其整治模式等方面的研究。     

呼伦贝尔沙地2000-2020年土地利用变化及生态服务价值

[目的] 研究呼伦贝尔沙地土地利用动态以及生态系统服务功能演变情况,为该区优化土地利用结构以及改善生态服务功能提供理论支撑。[方法] 以呼伦贝尔沙地2000,2005,2010,2015和2020年5期遥感影像为数据源,在ENVI 5.3和ArcGIS 10.2的支持下,运用土地动态度空间分析模型、变化强度分析土地利用变化特征,采用中国沙地生态服务价值表的计算方法对呼伦贝尔沙地土地利用数据进行分析,计算呼伦贝尔沙地的生态服务价值以及敏感性指数。[结果] ①研究区沙漠化呈逆转趋势,各沙漠化土地面积均减少,极重度沙漠化土地面积共减少627.3 km²,林草地面积不断增加,生态环境得到了有效的改善;从土地利用类型变化来看,主要以沙漠化逐级转移为主,其他转换类型的转化比重相对较小;②从变化速率来看,林草地的变化幅度最大,以年变化率9.3%的速度增加;从变化强度的绝对值来看,轻度沙漠化的变化强度最大,20 a间面积减少70%;③呼伦贝尔沙地的生态服务价值总体呈现增长趋势,其中林草地生态服务价值最高,极重度沙漠化的生态服务价值最低;生态服务价值的敏感性指数均<1,说明沙地的生态服务价值相对较稳定。[结论] 研究区应扩大林草地面积,合理治理沙漠区域,提升区域生态系统服务价值。     

多变量洪水风险分析方法

分析了洪水特征值的不同频率性和现行的单因素防洪风险分析方法的片面性。从组合事件的概率理论出发,利用“完全相关”与“相互独立”两种特殊情况,采用模糊集理论,建立了二参数加权组合概率模型。模型中不仅考虑了洪峰和洪量对洪水风险的共同作用,而且避免了确定条件概率分布的问题,为在现有的洪水资料的情况下,合理估计防洪风险及进行防洪水利计算,提供了一种简单可操作性方法。     

The effect of monsoonal atmospheric moisture on lightning fire ignitions in southwestern North America

The seasonal arrival of increased atmospheric moisture associated with the North American monsoon in southwestern North America greatly affects the lightning fire regime. Dramatically increased lightning strikes from monsoon-related thunderstorm activity in July and August are counterbalanced by decreased ignition probability and fire spread due to increased atmospheric moisture and precipitation. Using 16 years of lightning flash, relative humidity, and precipitation data from a 34,800 km² study area with high lightning fire activity in Arizona and New Mexico, we quantified the effect of a single measure of atmospheric moisture, daily minimum relative humidity (DMRH), on observed lightning fire data. The probability that a lightning flash would ignite an observed fire was highly correlated with DMRH in the form of a power law, ranging from 0.023 on days with lowest humidity to <0.0001 on high humidity days. The number of observed lightning fires/day was highly correlated with DMRH in the form of a log–normal distribution peaking at 4.09 fires/day at 22.1% DMRH. Area burned/day was also correlated with DMRH with a log–normal distribution peaking at 53.7 ha/day at 16.5% DMRH. Despite strong relationships based on long-term aggregated data, large uncertainties at shorter time scales prevented using DMRH alone for daily or yearly fire prediction. Estimates of observed fire ignitions derived from existing models of ignition probability and survival based on fuel moisture closely approximated our real world data. Our results suggest that a model based on relative humidity provides a useful framework for understanding the lightning fire regime in this region.     

Using occupancy estimation to assess the effectiveness of a regional multiple-species conservation plan: Bats in the Pacific Northwest

Regional conservation plans are increasingly used to plan for and protect biodiversity at large spatial scales however the means of quantitatively evaluating their effectiveness are rarely specified. Multiple-species approaches, particular those which employ site-occupancy estimation, have been proposed as robust and efficient alternatives for assessing the status of wildlife populations over large spatial scales, but implemented examples are few. I used bats as a model to evaluate design considerations for the use of occupancy estimation to assess population status and habitat associations for eight species of bats covered under a regional conservation plan. Bats were one of the groups expected to benefit from a system of reserves for species associated with late-successional/old-growth (LSOG) habitat designated under the Northwest Forest Plan (NWFP). This study produced the first estimates for probabilities of occupancy and detection for bats at a regional scale. Overall probabilities of occupancy ranged from 0.586 to 0.783 and probabilities of detection ranged from 0.239 to 0.532 among the eight species modeled. Although point estimates of occupancy suggested association with NWFP habitat categories for some species, estimate precision was low. Models that assumed constant occupancy with respect to reserve- and LSOG-status were supported for most species. I used model-averaged estimates of occupancy and detection for each species to estimate survey effort necessary to meet precision targets. Occupancy estimation was best suited to species with the highest detection probabilities. Species that are rare or difficult to detect will require enhancement in survey methods or more intensive survey effort to produce meaningful estimates. Optimizing monitoring efforts to address multiple species requires tradeoffs among survey methods, levels of effort, and acceptable levels of precision.     

TO SOLVE PROBLEMS OF STRUCTURAL RELIABILITY BY MONTE CARLO METHOD

This paper uses simple and clear mathematical proving to expound the fundamental principle,usage and prospect of Monte Carlo method. This paper also gives an example which explains how Monte Carlo method is used for analysing structural reliabilty of engineering.     

Physiological investigations of management and genotype options for adapting rice production to iron toxicity in Madagascar

Iron (Fe) toxicity is one of the major mineral disorders affecting rice (Oryza sativa L.) production in Madagascar. This study aimed at linking physiological and agronomic responses of diverse rice genotypes to Fe resistance mechanisms with different nutrient management practices. Twenty‐three local and exotic rice varieties were grown in Fe‐toxic soil in parallel greenhouse and field experiments and subjected to two treatments: (1) no fertilizer; (2) mineral and organic fertilizer application at recommended rates. Growth, straw and grain yield, symptom formation, and physiological responses including Fe uptake, root plaque formation, and lipid peroxidation were monitored. The application of fertilizer significantly decreased average shoot Fe concentrations partly due to Fe exclusion favored by enhanced root plaque formation. Visual symptoms negatively correlated with straw biomass in both experiments and grain yield in the greenhouse experiment, and positively correlated with lipid peroxidation. However, no plausible correlation occurred with grain yield in the field due to sterility in exotic varieties un‐adapted to local climate. Even though grain Fe concentrations were orders of magnitude lower than in vegetative tissue, some exotic varieties were significantly superior to local checks. Our results provide insight into management and genotype options for adapting rice to Fe toxicity under field conditions.     

基于土地利用/覆被变化的贵阳市红枫湖水源保护区生态风险演变

以贵阳市饮用水源地红枫湖保护区为研究对象,基于1991年,2007年,2013年3期TM遥感影像解译数据,从生态风险评价的角度出发,利用ArcGIS,ERDAS IMAGINE平台,通过逐网格采样和空间克里金插值方法,研究红枫湖保护区不同时间范围内的土地利用变化及区域景观生态风险演变。结果表明:近22 a主要以中间等级生态风险为主,1991—2007年低生态风险、较低生态风险和中生态风险所占面积比例均下降。2007—2013年低生态风险、较低生态风险和高生态风险面积比例均呈现上升趋势。土地利用转移则以林地、耕地、建设用地最为显著,耕地总体呈现降低趋势,而林地、建设用地总体则呈现上升趋势。     

基于随机降雨模拟的灌区塘坝蓄水方案优化

结合南方丘陵灌区塘坝分布广、数量多、群体容量大的特点,建立库塘水资源系统优化调控模型。以漳河灌区的子灌区——杨树垱水库灌区为研究实例,应用蒙特卡洛法模拟出长序列的旬降雨,采用正交试验法选出每个模拟年份的最优塘坝控制运行方案,并对控制运行规律进行统计分析,得到不同典型年下塘坝的控制运行规则：在平水年时5月底、6月上旬末、6月下旬末、7月上旬末预留30%,6月中旬末预留10%,7月中旬末预留20%,其他各旬可全部用完;在偏枯水年时5月底预留10%,6月上旬末、6月下旬末预留20%,6月中旬末、7月上旬末、7月中旬末预留30%,其他各旬可全部用完;在特枯水年时5月底、7月中旬末预留10%,6月上旬末、6月中旬末预留30%,6月下旬末、7月上旬末、7月下旬末预留20%,其他各旬可全部用完。比较塘坝在不控制运行与优化控制运行下保证基本产量的概率,结果表明：在平水年时,相对产量在0.6以上的概率提高了2.38%;在偏枯水年时,相对产量在0.6以上的概率提高了8.80%;在特枯水年时,相对产量在0.6以上的概率提高了11.29%。研究从定量分析的角度,以单位面积产量最大为目标,提出塘坝的控制运行规则,对指导水库、塘坝的联合运行,提高灌区的灌溉效益具有重要意义。