运用混沌理论制作长期灾害预报模型初探

为了提供准确的农业灾害预报，本研究运用混沌理论，以北京历年重大旱灾预报为例，构建了长期灾害混沌预报模型。该模型采用便于描绘混沌事件的三阶差分方程与多因子状态方程联立，模拟出北京市1955－2001年的历次旱灾事件发生过程。按照该模型规定的法则做重大旱灾预测比用单纯统计预测的准确率有显著提高。灾害混沌预报模型可作为长期灾害预测的新途径。     

海气耦合随机模式的CO_2温室效应的研究

从海－气相互作用的角度出发，研究了ＣＯ_２温室效应对海温距平的影响；建立了非线性海－气耦合随机模式及绝热条件下的朗之万动力学方程和福克－普朗克方程，并给出了方程组的解析解为高斯分布，在稳态情况下为布朗运动，得到了在ＣＯ_２加倍时海温距平平均值增温为１．８１℃，与当前研究ＣＯ_２对大气温度影响的结果一致。     

框架与框架填充墙结构的统计损伤诊断

提出了一种基于递推随机有限元方法(RSFEM)的随机结构损伤识别方法来识别框架与框架填充墙结构的损伤.在定义了随机损伤指数概念的基础上,考虑模型误差的不确定性和测量噪声的影响,建立了关于随机损伤指数的控制方程.然后,利用RSFEM得到了结构随机损伤指数的统计特性.数值算例的结果显示,新的方法与两步法结合能在考虑模型误差和测量噪声的情况下对结构损伤进行有效识别,且在结构随机参数有较大涨落情况下,该方法与蒙特卡洛模拟法同样有效.     

长期定位施肥对土壤腐殖质理化性质的影响

 以潮土、旱地红壤和红壤性水稻土为研究对象 ,探讨了长期施肥对土壤腐殖质含量与性质的影响。结果表明 ,长期施肥不仅影响土壤腐殖质的含量与组成 ,还影响腐殖质的理化性质。施有机肥或有机无机肥配施降低潮土和旱地红壤胡敏酸的E4和E6值 ,提高红壤性水稻土胡敏酸的E4和E6值。单施化肥也能提高红壤性水稻土胡敏酸的E4和E6值 ,但对潮土和旱地红壤胡敏酸E4和E6值影响不大。长期施肥对土壤耕层富里酸可见光谱的影响与胡敏酸不同 ,施有机肥或有机无机肥配施均能提高 3种土壤富里酸的E4和E6值 ,单施化肥对 3种土壤富里酸的E4和E6值基本上没有影响。长期施肥也影响腐殖质的紫外吸收光谱 ,长期施用有机肥或有机无机肥配施均能提高 3种土壤胡敏酸和富里酸的紫外吸收光谱值 ,但这种作用只在短波长方向明显 ,随着波长的增加影响减小。单施化肥也可以提高富里酸的紫外吸收值 ,但只能提高潮土胡敏酸的紫外吸收值。长期施用有机肥或有机无机肥配施均能提高 3种土壤胡敏酸和富里酸的总酸性基、羧基和酚羟基含量 ,单施化肥对胡敏酸和富里酸含氧功能团含量的影响不大     

用谐波叠加法重构随机道路不平顺高程的时域模型

道路时域建模对道路车辆振动时程分析、车辆台架试验、路面损伤以及车路耦合动力学研究均具有重要意义。谐波迭加法是一种既简单直观而又具有严密数学基础的构造道路时域模型的方法。本文基于随机道路的统计量描述，再现了随机道路针对路面车辆的单点激励和单轮辙激励的时间历程样本，完善了所生成样本的标定方法。对双轮辙激励，采用空间相关的两随机过程模拟，将两过程用虚拟的线性系统联接，建立其符合道路相干函数的传递关系，最终得到道路车辆的双轮辙多点时空相关性激励模型。该模拟方法的数学理论正确，适用于任意指定谱特征的随机道路模拟，对     

Phosphate Fertilizers for Sugarcane Used at Pre-Planting (Phosphorus Fertilizer Application)

Phosphate applications are still rare in sugarcane cultivation and can be done with phosphorus fertilizers of residual over. This study aims to evaluate the agronomic efficiency of phosphate fertilization before sugarcane planting and its effect on sugarcane yield. The study was carried out over three crop cycles at the Jalles Machado sugar-mill in Goianésia, GO, Brazil. The treatments consisted of five different phosphorus sources (soluble and insoluble) applied at a rate of 300 kg ha^?1 phosphorus pentoxide (P₂O₅). The phosphorus fertilizers used were: triple superphosphate, mono-ammonium phosphate (MAP), Arad rock phosphate, Itafós rock phosphate, and magnesium term phosphate. The effects of these fertilizers were evaluated by plant height (ground to Top Visible Dewlap; TVD), leaf phosphorus content, agronomic efficiency, and sugarcane yield from cane-plants, first ratoon, and second ratoon. Magnesium term phosphate and triple superphosphate resulted in greater plant-cane height. Leaf phosphorus concentrations were highest with applications of MAP, magnesium term phosphate, and triple superphosphate. Phosphate applications did not affect sugarcane plant yield, but did increase ratoon yield. In general, the residual effect of insoluble phosphate increased over the years. The agronomic efficiency (AE) of phosphate was (in descending order): triple superphosphate (100%), term phosphate (89%), MAP (80%), Itafós rock phosphate (67%), and Arad rock phosphate (60%).     

Long‐term effects of fertilization on some soil properties under rainfed soybean‐wheat cropping in the Indian Himalayas

This study aims to examine the effects of long‐term fertilization and cropping on some chemical and microbiological properties of the soil in a 32 y old long‐term fertility experiment at Almora (Himalayan region, India) under rainfed soybean‐wheat rotation. Continuous annual application of recommended doses of chemical fertilizer and 10 Mg ha^–1 FYM on fresh‐weight basis (NPK + FYM) to soybean (Glycine max L.) sustained not only higher productivity of soybean and residual wheat (Triticum aestivum L.) crop, but also resulted in build‐up of total soil organic C (SOC), total soil N, P, and K. Concentration of SOC increased by 40% and 70% in the NPK + FYM–treated plots as compared to NPK (43.1 Mg C ha^–1) and unfertilized control plots (35.5 Mg C ha^–1), respectively. Average annual contribution of C input from soybean was 29% and that from wheat was 24% of the harvestable aboveground biomass yield. Annual gross C input and annual rate of total SOC enrichment from initial soil in the 0–15 cm layer were 4362 and 333 kg C ha^–1, respectively, for the plots under NPK + FYM. It was observed that the soils under the unfertilized control, NK and N + FYM treatments, suffered a net annual loss of 5.1, 5.2, and 15.8 kg P ha^–1, respectively, whereas the soils under NP, NPK, and NPK + FYM had net annual gains of 25.3, 18.8, and 16.4 kg P ha^–1, respectively. There was net negative K balance in all the treatments ranging from 6.9 kg ha^–1 y^–1 in NK to 82.4 kg ha^–1 y^–1 in N + FYM–treated plots. The application of NPK + FYM also recorded the highest levels of soil microbial‐biomass C, soil microbial‐biomass N, populations of viable and culturable soil microbes.     

Improving minimum detectable differences in the assessment of soil organic matter change in short‐term field experiments

The demand for information on cropping system impact on soil organic matter (SOM) calls for efforts to improve the utilization of short‐term field experiments (e.g., to evaluate the parameterization of cropping systems in models). Those approaches have coped with the problem of determining small SOM changes within a large background mass. Thus, objectives of this survey are (1) the improvement of the minimum detectable difference (MDD) in SOM in the hudycrop short‐term field experiment by methods of sampling design and data treatment, (2) the verification to what extend the hudycrop short‐term field experiment allows for the determination of management induced effects on SOM, and (3) the investigation to what extent the obtained results may be suitable to evaluate the parameterization of a SOM balance model. The design of the hudycrop is suitable for excluding outliers plotwise. The estimation of plot means can be improved by the sampling design. Instead of determining a single plot mean in a mixed sampling procedure, the design provides multiple values for each plot, allowing for the identification of extreme values before calculating plot means. In consequence, minimum detectable differences decrease by a factor of 0.53 for soil organic C (SOC) and 0.63 for soil total N (STN) masses, allowing for detection of changes in the magnitude of 3.7 and 2.6% of background SOC and STN levels, respectively. Differences between treatments, however, are significant with corrected values (after outlier exclusion) for the crop production systems with the highest impact (potatoes and mulched red clover). Determining outliers based on Student's t‐test gives the lowest MDD and is therefore considered to be the most suitable method in this case. Correlations between apparent changes and SOM balances according to the HU‐MOD–2 model, used in this survey, indicate that the experimental design, in principal, is suitable for the evaluation of the parameterization of crop production systems in models. Still, an improved precision in SOM change detection is necessary. Reasonable options for that purpose are discussed in the paper.     

我国肉羊散养的成本效率及其影响因素

为促进我国肉羊产业发展提供参考,基于2006—2012年肉羊生产相关数据,运用随机前沿分析法对河北、黑龙江、山东、河南、陕西和新疆的肉羊散养成本效率进行测算,分析其变化趋势,探讨其影响因素。结果表明：河北、黑龙江、山东、河南、陕西和新疆的肉羊散养成本效率总体呈波动上升趋势,存在不同程度的成本非效率情况,距离最优效率水平仍有一定差距,尚有较大的提升空间。料肉比与成本效率呈负相关,降低料肉比能够提高成本效率;疫病是导致成本效率低下的主要因素。     

辐射作用下含修复DNA主链断裂随机动力学理论的研究——单链与双链断裂规律

按照我们在文献[1]中给出的辐射诱发含修复DNA主链断裂随机动力学理论数学模型,在此基础上,本文进一步导出了两种不同形成过程的双链断裂变化规律。在一定近似下,可以对SSB及DSB的实验结果作出满意的解释。我们的理论可以避免靶学说与击中理论的主要缺点,在一定条件下则又可以还原为靶理论结果,而且本理论还具有容纳更多因素的优点。