Mechanistic Drifting Forecast Model for A Small Semi-Submersible Drifter Under Tide–Wind–Wave Conditions

Understanding the drifting motion of a small semi-submersible drifter is of vital importance regarding monitoring surface currents and the floating pollutants in coastal regions. This work addresses this issue by establishing a mechanistic drifting forecast model based on kinetic analysis. Taking tide–wind–wave into consideration, the forecast model is validated against in situ drifting experiment in the Radial Sand Ridges. Model results show good performance with respect to the measured drifting features, characterized by migrating back and forth twice a day with daily downwind displacements. Trajectory models are used to evaluate the influence of the individual hydrodynamic forcing. The tidal current is the fundamental dynamic condition in the Radial Sand Ridges and has the greatest impact on the drifting distance. However, it loses its leading position in the field of the daily displacement of the used drifter. The simulations reveal that different hydrodynamic forces dominate the daily displacement of the used drifter at different wind scales. The wave-induced mass transport has the greatest influence on the daily displacement at Beaufort wind scale 5–6; while wind drag contributes mostly at wind scale 2–4.

Understanding yields in alley cropping maize (Zea mays L.) and Cassia siamea Lam. under semi-arid conditions in Machakos, Eastern Kenya

Six seasons of experiments in Machakos, Kenya, revealed that above about 150 mm of rainfall, maize yields per row in alley cropped “replacement” agroforestry (AF) plots, of Cassia siamea Lam. and maize ( Zea mays, cv. Katumani Composite B), may be expected to exceed those in the control (sole maize) plots. Such yields were insufficient to compensate for the area “lost” to the hedgerows. Below about 150 mm the control plots may be expected to perform better. This result was due to competition for water. Greater association of the fine roots of Cassia and maize was observed in the middle of the alleys than near the hedgerows. Photosynthetic consequences of shading were insignificant relative to other factors. In the alleys, reductions of soil temperature due to shade in the western and eastern maize rows were higher than in the middle row. Soil moisture extraction was higher in the AF than in the control plots. In the AF plots, moisture extraction was greater under the central maize rows than under those nearest the Cassia. Yield patterns followed such soil temperature and soil moisture patterns. Maize transpiration and photosynthetic rates were significantly higher in the control than in the AF plots during a below average rainy season but not during above average rainy seasons. It is concluded that alley cropping under semi arid conditions should be approached differently from the system worked on. It must at least provide strong physical protection of crops and/or soils and have a strong economic incentive to be of interest to the farmers.

Necessary Optimality Conditions for Multi-Objective Semi-Infinite Variational Problem

In this paper, necessary optimality conditions for a class of Semi-infinite Variational Problems are established which are further generalized to a class of Multi-objective Semi-Infinite Variational Problems. These conditions are responsible for the development of duality theory which is an extremely important feature for any class of problems, but the literature available so far lacks these necessary optimality conditions for the stated problem. A lemma is also proved to find the topological dual of as it is required to prove the desired result.

The Optimality Conditions for Multiobjective Semi-infinite Programming Involving Generalized Unified （C, α, p, d）-convexity

The definition of generalized unified (C, α, ρ, d)-convex function is given. The concepts of generalized unified (C, α, ρ, d)-quasiconvexity, generalized unified (C, α, ρ, d)-pseudoconvexity and generalized unified (C, α, ρ, d)-strictly pseudoconvex functions are presented. The sufficient optimality conditions for multiobjective nonsmooth semi-infinite programming are obtained involving these generalized convexity lastly.

Left-definite boundary conditions of Sturm-Liouville problems when the interval shrinks to a point

On the condition that the interval of the problem shrinks to a point, we investigated the separated boundary conditions Sα,β of left-definite Sturm-Liouville problem, and answered the following question： Is there a co ∈ J such that Sα,β is always left-definite or semi-left-definite for the Sturm-Liouville equation for each c ∈ （a, co）？

Growing Sandpile Problem with Local and Non-Local Boundaries Conditions

In this paper, we study a class of Prigozhin equation for growing sandpile problem subject to local and a non-local boundary condition. The problem is a generalized model for a growing sandpile problem with Neumann boundary condition (see [1]). By the semi-group theory, we prove the existence and uniqueness of the solution for the model and thanks to a duality method we do the numerical analysis of the problem. We finish our work by doing numerical simulations to validate our theoretical results.

Solution of the Matrix Second Semi-Tensor Product Equation A ∘ l X ∘ l B=C

In this paper, the solution of the matrix second semi-tensor product equation A∘lX∘lB=Cis studied. Firstly, the solvability of the matrix-vector second semi-tensor product equation is investigated. At the same time, the compatibility conditions, the sufficient and necessary conditions and the specific solution methods for the matrix solution are given. Secondly, we further consider the solvability of the second semi-tensor product equation of the matrix. For each part, several examples are given to illustrate the validity of the results.

Interaction between climate and management on beta diversity components of vegetation in relation to soil properties in arid and semi-arid oak forests, Iran

This study aimed to investigate the interaction between regions with different climatic conditions(arid vs. semi-arid) and management(protected vs. unprotected) on the turnover and nestedness of vegetation in relation to physical, chemical and biological properties of soils in the Ilam Province of Iran. In each of the two regions, we sampled 8 sites(4 managed and 4 unmanaged sites) within each of which we established 4 circular plots(1000 m^2) that were used to investigate woody species, while two micro-plots(1 m×1 m) were established in each 1000-m^2 plot to analyze herbaceous species. In each sample unit, we also extracted three soil samples(0–20 cm depth) for measuring soil properties. The results indicated that the interaction between region and conservational management significantly affected the percent of canopy cover of Persian oak(Quercus brantii Linddl), soil respiration, substrate-induced respiration, as well as beta and gamma diversities and turnover of plant species. The percent of oak canopy cover was positively correlated with soil silt, electrical conductivity, available potassium, and alpha diversity, whereas it was negatively correlated with plant turnover. In addition, plant turnover was positively related to available phosphorus, while nestedness of species was positively related to organic carbon and total nitrogen. According to these results, we concluded that physical, chemical, and biological characteristics of limited ecological niche generally influenced plant diversity. Also, this study demonstrated the major contribution of the beta diversity on gamma diversity, especially in semi-arid region, because of the higher heterogeneity of vegetation in this area.

General semi-analytical solutions to one-dimensional consolidation for unsaturated soils

This paper presents general semi-analytical solutions to Fredlund and Hasan＇s one-dimensional （1D） consolidation equations for unsaturated soils subject to different initial conditions, homogeneous boundaries and time-dependent loadings. Two variables are introduced to transform the two-coupled governing equations of pore-water and poreair pressures into an equivalent set of partial differential equations （PDEs）, which are solved with the Laplace transform method. The pore-water and pore-air pressures and settlement are obtained in the Laplace transform domMn. The Crump＇s method is used to perform inverse Laplace transform to obtain the solutions in the time domain. The present solutions are more general in practical applications and show good agreement with the previous solutions in the literature.

Phenotypic nutrient up-take differences in an alley cropping system in semi-arid Machakos, Kenya

Alley cropping of Cassia siamea and maize was studied in semi arid Kenya for soil fertility improvement. Katumani composite maize was planted except in the short rains of 1988 (SR88) when a hybrid variety was sown. Therefore the grain yield per row increased differently in the alley cropped maize (CM). Sole maize (SM) and CM yields were higher in SR88 than in the long rains of 1988 (LR88) by 62% and 38%, while yields from the same treatments in LR89 were only 21% and 45% of those in SR88 These differences in relative maize yields are attributed to differences between the two maize varieties in competition under nutrient stress conditions.

Semi-Automatic Modeling Technique of Torque Converter Flow Passage

The modeling technique of hydrodynamic torque converter flow passage was investigated. The semi-automatic modeling technique of torque converter flow passage was proposed. The flow passage model of each converter wheel is considered as a revolution entity sliced by two curved surfaces. In order to generate the revolution entity, a new approximation method, condition optimum arc approximation, was proposed. The method was used to approximate the meridional streamlines of the inner and outer wall. As a result, the three-dimensional revolution entity can be conveniently generated. In order to create slice surfaces, the central stream surface of flow passage was approximated with a quadric surface. The normal vector of the quadric surface and the thickness/thickness-function of bade were used to calculate the discrete point coordinates of blade surfaces. Via the rotation transformation to the coordinates, the discrete point coordinates of slice surfaces were obtained. A parameterized program code used for the hydrodynamic torque converter design and semi-automatic modeling was developed. Modeling errors were calculated and analyzed. The flow passage model was generated in several minutes with the help of the program code, Auto CAD and Solidworks software. Finally, the model was inputted into Gambit, and the pre-processing task used for the numerical simulation of torque converter flow field was successfully completed. The investigation results show that the semi-automatic modeling not only can ensure the accuracy of modeling, but also librates the research and design workers of torque converter from the time-consuming modeling work, which paves the way for the numerical simulation of the complex flow field of the hydrodynamic torque converter.

More Properties of Semi-Linear Uniform Spaces

In this paper we shall generalize the definition given in [1] for Lipschitz condition and contractions for functions on a non-metrizable space, besides we shall give more properties of semi-linear uniform spaces.

Convergence theorem of common fixed points for Lipschitzian pseudo-contraction semi-groups in Banach spaces

The purpose of this paper is to study the weak convergence problems of the implicity iteration process for Lipschitzian pseudocontractive semi-groups in the general Banach spaces. The results presented in this paper extend and improve the corresponding results of some people.

Surface Wave Echo in a Semi-Bounded Plasma

Plasma echo theory is revisited to apply it to a semi-bounded plasma. Spatial echoes associated with plasma surface wave propagating in a semi-bounded plasma are investigated by calculating the second order electric field produced by external charges and satisfying the boundary conditions at the interface. The boundary conditions are two-fold: the specular reflection condition and the electric boundary condition. The echo spots are determined in terms of the perpendicular coordinate to the interface and the parallel coordinate along which the wave propagates. This improves the earlier works in which only the perpendicular coordinate is determined. In contrast with the echo in an infinite medium, echoes in a bounded plasma can occur at various spots. The diversity of echo occurrence spots is due to the discontinuity of the electric field at the interface that satisfies the specular reflection boundary condition. Physically, the diversity appears to be owing to the reflections of the waves from the interface.

2种水分条件下华北落叶松林的林下日蒸散量变化差异

【目的】探讨土壤湿度对华北落叶松Larixprincipis-rupprechtii林下日蒸散变化的影响,为理解林地蒸散适应气候变化的机制及制定林水协调管理方案提供理论基础。【方法】以宁夏六盘山半干旱区叠叠沟小流域华北落叶松人工林为对象,设置了遮断降水输入(防水处理)和自然降水输入2种处理,人为加大土壤湿度梯度,分析2种土壤湿度条件下气温、太阳辐射、降水量等因子对林下日蒸散量的影响。【结果】在8、9、10月,自然降水的林下日蒸散量分别为67.06、36.32、29.49 mm·d^(-1),防水处理分别为54.22、20.07、11.35 mm·d^(-1),各月自然降水下的日蒸散量均大于防水处理。2种水分条件的林下日蒸散量随时间进程总体呈逐渐减小趋势,且自然降水下波动大于防水处理。8—10月,2种水分条件的林下日蒸散量差值总体呈先升后降的波浪状变化,比值总体呈逐渐升高的波浪状变化;在8、9、10月,各日自然降水日蒸散量与防水处理日蒸散量之差的均值依次为0.41、0.54、0.59 mm·d^(-1),比值依次为1.29、1.91、2.74。随潜在蒸散增大,2种水分条件的林下日蒸散量差与土壤体积含水量差的比值逐渐增加。土壤湿度对林下蒸散的影响在日潜在蒸散量小于3 mm·d^(-1)时较小,在大于3 mm·d^(-1)时增大,在大于5 mm·d^(-1)时增大极为明显。【结论】2种水分条件的林下蒸散影响因子大致相同,区别为自然降水的林下日蒸散量更多受降水影响,而防水处理则更多受土壤湿度影响。未来应增加多个土壤湿度梯度对林下蒸散差异的影响研究。图7表1参28.

复杂等离子体光子晶体能带结构计算

等离子体光子晶体是由等离子体和其他介电材料或者真空构成的,具有周期性结构,其可调控的带隙特性使得等离子体光子晶体在滤波器、等离子体隐身衣和等离子体透镜等军事医学器件制造上具有广泛的应用。因此,通过改变等离子体的密度、温度等参数来获取满足特定需求的能带结构特性便有着非常重要的意义。基于上述考虑,提出Petrov-Galerkin有限元计算方法来求解并分析等离子体光子晶体的带隙特性。该方法的核心思想是构造在边界上系数互为倒数的基函数和测试函数所构成的空间,在消除边界上积分的同时降低自由度。采用的网格为半笛卡尔投影网格,该网格能适应复杂等离子体柱形状。在建立弱形式时将界面非线性连续条件线性化,简化了界面积分项的处理。通过绘制数值算例的能带结构图,分析验证了等离子体电子密度、等离子体光子晶体柱的填充率和形状等因素对带隙宽度、带隙位置、耦合带隙以及截止频率造成的影响,从而实现等离子体光子晶体能带结构的可调控性。

半田间环境条件下叉角厉蝽对草地贪夜蛾幼虫的捕食能力

为科学评估我国优势天敌昆虫叉角厉蝽Eocanthecona furcellata对重要农业害虫草地贪夜蛾Spodoptera frugiperda的捕食作用,在笼罩条件下,采用功能反应方法评价了叉角厉蝽3龄和5龄若虫及雌成虫对草地贪夜蛾3龄和5龄幼虫的捕食能力。研究表明,除叉角厉蝽3龄若虫不能独立捕食草地贪夜蛾5龄幼虫外,叉角厉蝽其它虫态对草地贪夜蛾幼虫的捕食量均随猎物密度的升高而增加,捕食率则随猎物密度的升高而逐渐下降,经Logistic回归方程判别为II型功能反应。拟合的Rogers’随机捕食者方程参数表明,叉角厉蝽3龄和5龄若虫及雌成虫对草地贪夜蛾3龄幼虫的瞬时攻击率a分别为0.0295、0.0453和0.0965,处置单头猎物的时间Th分别为3.98 h、1.36 h和1.21 h,理论日最大捕食量T/Th分别为6.03头、17.65头和19.83头;叉角厉蝽5龄若虫和雌成虫对草地贪夜蛾5龄幼虫的瞬时攻击率a分别为0.0545和0.0876,处置单头猎物的时间Th分别为3.67 h和4.83 h,理论日最大捕食量T/Th分别为6.54头和4.97头。结果表明,在笼罩条件下叉角厉蝽3龄若虫的捕食能力最弱,除不能有效捕食草地贪夜蛾5龄幼虫外,对草地贪夜蛾3龄幼虫的捕食量也远低于5龄若虫和雌成虫,而叉角厉蝽5龄若虫和雌成虫的捕食能力较强,能有效捕食草地贪夜蛾的3龄和5龄幼虫,两者的捕食量相近。研究结果可为合理利用叉角厉蝽防治草地贪夜蛾提供实践参考。

面向商用车驾驶室俯仰振动的半主动悬置控制策略

商用车在经过减速带、凹坑等冲击工况时会产生较大的俯仰角,此时应采取与正常路面行驶时不同的控制策略对阻尼进行控制。首先,提出一种混合控制策略,该控制策略将一种改进天棚控制和改进单传感器控制进行融合,可以根据路面条件和车辆状态等信息,来调整不同的算法的权重。通过实车数据确定各控制器参数。同时在实车中进行部分控制策略的验证,结果显示,该控制策略能够有效地提升车辆乘坐舒适性。在1/2半车模型上进行不同冲击路面仿真分析,结果表明,该控制策略在降低簧上质量加速度和俯仰角加速度方面有着较好的优化效果,也在全频域内有较好的控制效果。

极端工况下浅水大型半潜漂浮式风机动态响应分析

利用WADAM程序进行三维辐射/衍射频域分析计算,计算时域分析所需的相关水动力系数,如附加质量、辐射阻尼、一阶/二阶波浪力传递函数和RAO等。优化设计一套适用于浅水的悬链式系泊系统,利用ORCAFLEX开展对大型半潜漂浮式风机在50年一遇极端工况下风浪流耦合环境条件模拟。分析大型半潜浮式风机在极端工况下完整系泊和考虑系泊失效(单缆破断)情况下的运动响应、塔顶加速度及锚链设计张力等风机关键控制参数。结果表明,该大型半潜漂浮式风机稳定性好,完整系泊和单缆破断运动和系泊性能表现优异,风机关键控制参数均能满足50年一遇极端工况的设计值要求。

基于仿真机理和改进回归决策树的二噁英排放建模

城市固废焚烧(Municipal solid waste incineration,MSWI)过程是“世纪之毒”二噁英(Dioxin,DXN)的重要排放源之一.截止目前为止,DXN的演化机理和实时检测仍是尚未解决的难题.现有研究主要基于离线化验数据构建数据驱动模型,DXN的检测未有效结合燃烧过程机理.针对该问题,本文提出基于仿真机理和改进线性回归决策树(Linear regression decision tree,LRDT)的DXN排放建模.首先,采用基于床层固废燃烧模拟软件FLIC(Fluid dynamic incinerator code)和过程工程先进系统软件(Advanced system for process engineering Plus,Aspen Plus)耦合的数值仿真模型,获取蕴含多运行工况的虚拟机理数据;接着,利用虚拟机理数据构建基于改进LRDT的CO_(2)、CO和O_(2)燃烧状态表征变量模型;然后,以真实CO_(2)、CO、O_(2)作为输入和以DXN真值作为输出,构建多入单出LRDT的过程映射模型(Process mapping model,PMM),再利用该模型进行半监督学习和结构迁移得到机理映射模型1(Mechanism mapping models1,MMM1);最后,通过结构增量学习获得基于半监督迁移学习的MMM2模型.在实验室的半实物平台和北京某MSWI厂的边侧验证平台对所提方法进行了工业应用验证.实验结果证明了所提方法与研发的软测量系统可有效实现二噁英排放浓度在线检测.