1993年汛期黄河下游河势遥感调查

利用ＭＥＲＩＤＩＡＮ遥感图象处理系统，通过ＴＭ图象最佳波段组合、线性拉伸放大、密度分割等处理手段，首次在黄河上进行了卫星遥感河势调查，其优势在于：（１）可以弥补目估河势的不足；（２）能够对河势流路、主流线位置、洪漫滩范围及水边线、生产堤、主要滩区洪水进出口门位置、进水和水围村庄等准确定位；（３）可以详细计算各类滩区面积与分布密度。     

Short communication: reference values for blood parameters in Holstein dairy cows: effects of parity, stage of lactation, and season of production

Confidence intervals for blood parameters used for nutritional and metabolic profile testing in cattle were calculated for clinically normal lactating Holstein cows, taking into account the effects of parity, stage of lactation, and season. Blood samples were collected from 740 cows in 33 Italian dairy herds according to a predefined protocol. Herds were visited during summer and the following winter, sampling 12 lactating cows at each visit (4 primiparous and 8 multiparous). Six cows were selected from the early-lactation group (days in milk: 10 to 89) and the other 6 were selected from the mid-lactation group (days in milk: 90 to 215). Cow selection criteria excluded animals clinically exposed to periparturient diseases as well as animals not considered in good health by a veterinary clinical examination. For each blood variable, outliers were identified and discarded. Data were then analyzed for their Gaussian distribution and variables with not normal distribution were log-transformed to adjust for lack of normality. Herd mean values were calculated for each blood parameter according to 3 main classification factors: parity (primiparous vs. multiparous), stage of lactation (early vs. mid) and season of production (summer vs. winter). The resulting data set was statistically analyzed using a mixed model with the fixed effects of these factors, their interactions, and the random effect of herd. General 95% confidence intervals were calculated for blood variables that showed a relevant herd variance component such as albumin, triglycerides, aspartate, urea, glucose, alanine aminotransferase, lactate dehydrogenase, direct and total bilirubin, calcium, magnesium, and potassium. For the remaining parameters, specific confidence intervals were calculated for each level of the significant main factors. Parity affected blood concentration of total protein, globulin, creatinine, alkaline phosphatase, gamma glutamyl transferase, creatinine kinase, and phosphorus. Blood nonesterified fatty acids, aspartate aminotransferase, gamma glutamyl transferase, creatinine kinase and cholesterol were influenced by stage of lactation. The season of production had a significant effect on total protein, globulin, creatinine, alkaline phosphatase, phosphorus, sodium, and chlorine. The outcomes of this work will improve the accuracy of the biochemical profile as a tool for dairy practitioners to assess the metabolic status of lactating Holstein cows.     

混合式热泵系统在"三北"地区应用前景分析

针对传统的空气源热泵难以在我国“三北”地区的特定气候条件下运行的问题,笔者曾提出一种可应用于低温环境下、由空气/水和水/水热泵机组组成的混合式热泵系统,并对其进行了实验研究.本文通过对实验结果的分析,研究了该系统在不同运行工况下的制热能效比REE和单、双级运行模式的切换条件;在“三北”各地区分别选取3个代表城市,利用B IN气象参数和温度频率法模拟计算出系统在这些地区应用的供热季节性能系数(FHSP),分析了混合式热泵系统在“三北”地区的应用前景和推广价值.     

基于Elman网络的黄河源区枯期径流预报

采用反馈Elman网络,对黄河唐乃亥水文站及上游玛曲站近45年(1959～2003年)年降雨及径流流量进行分析,建立了基于反馈神经网络的黄河源区枯季径流预报模型.利用Matlab7 神经网络工具箱对黄河源区唐乃亥水文站枯季径流量进行了预报.结果表明所建立的ANN(7,7,15,7)模型预报结果精度高,容错能力强,是枯季径流预报的有效手段.     

太湖地区麦季氮素淋失特征

通过排水采集器模拟试验,研究了太湖地区不同施肥水平下,麦作期间农田氮素淋洗特点。结果表明,麦季氮素渗漏损失以NO3--N为主,占总氮量的36.2%～99.1%,平均高达82.9%,NO3--N淋洗量随施肥量的增加而增加。不同施肥水平及肥料种类,对于NO3--N淋洗有着不同的影响,在试验的施肥水平下,麦作期间氮素淋失对地下水存在潜在污染。     

Satellite radar remote sensing of seasonal growing seasons for boreal and subalpine evergreen forests

We evaluated whether satellite radar remote sensing of landscape seasonal freeze-thaw cycles provides an effective measure of active growing season timing and duration for boreal and subalpine evergreen forests. Landscape daily radar backscatter measurements from the SeaWinds scatterometer on-board the QuikSCAT satellite were evaluated across a regional network of North American coniferous forest sites for 2000 and 2001. Radar remote sensing measurements of the initiation and length of the growing season corresponded closely with both site measurements and ecosystem process model (BIOME-BGC) simulations of these parameters because of the sensitivity of the K_u-band scatterometer to snow cover freeze-thaw dynamics and associated linkages between growing season initiation and the timing of seasonal snowmelt. In contrast, remote sensing estimates of the timing of growing season termination were either weakly or not significantly associated with site measurements and model simulation results, due to the relative importance of light availability and other environmental controls on stand phenology in the fall. Regional patterns of estimated annual net primary production (NPP) and component photosynthetic and autotrophic respiration rates for the evergreen forest sites also corresponded favorably with remote sensing estimates of the seasonal timing of spring thaw and associated growing season length, indicating the importance of these parameters in determining spatial and temporal patterns of NPP and the potential utility of satellite radar remote sensing for regional monitoring of the terrestrial biosphere.     

在严寒季节施工时砼的防冻与裂缝控制

在-26．5℃～-18℃的低温条件下进行砼工程施工时，依据经验及保温能力预先对砼的出机温度及入模温度进行了假定性计算，而后据此对砼施工的全过程进行了温度控制，确保了砼工程的施工质量，总结出了一套操作性强的技术措施。     

长期培肥黑土脱氢酶活性动态变化及其影响因素

对东北典型黑土区长期不同培肥黑土脱氢酶活性在作物生长季的动态变化进行研究。结果表明,施用有机肥,生长季黑土总体脱氢酶活性显著高于施用化肥和不施肥,其生长季脱氢酶活性保护容量在5.5 mg TPF/kg土.h以上,黑土总体脱氢酶活性施用高量有机肥>低量有机肥>不施肥>化肥,季节性变化波动性大。长期施用高量有机肥脱氢酶活性最大峰值出现在拔节期,施用低量有机肥、化肥和不施肥最大峰值出现在完熟期;长期施用不同数量和种类肥料所引起的黑土总体脱氢酶活性差异并未因玉米生长影响而改变,说明长期施用高量有机肥黑土微生物氧化活性能力增强,土壤自身调解和维持肥力能力增强。黑土脱氢酶活性的动态变化与绝大多数土壤生物、理化特性指标的动态变化没有显著的相关性;总体脱氢酶活性与多数土壤生物、理化特性因子、植物全磷、钾含量有极显著和显著正相关关系。     

赣江尾闾河网地形变化对洪季水动力的影响北大核心CSCD

为探明在新水沙条件和人类活动的影响下赣江尾闾河网地形变化与洪季水动力特征变化的关系,以1998—2020年为研究时段,基于1998、2013、2020年河道地形,分别建立一维河网数学模型,复演赣江98特大洪水,研究不同时期地形变化对洪季水动力特征的影响。结果表明:赣江尾闾河网的整体下切使水位流量关系右移,洪期各支洪峰流量整体增加,相同水位下,外洲站来流增幅超过50%。1998—2020年期间,南支地形下切幅度大于其他各支,地形不均匀下切导致尾闾河网节点分流比改变,整体上主支与南支分流增多、中支与北支分流减少。各支流速变化剧烈,主支下游流速增幅超过1 m/s。本研究可为河道整治规划、堤坝防护和灾害预防提供一些技术参考。