Prediction of efficient outputs based on GM(1,N) model and weak DEA efficiency

This paper expresses the efficient outputs of decisionmaking unit（DMU） as the sum of ＂average outputs＂ forecasted by a GM（1,N） model and ＂increased outputs＂ which reflect the difficulty to realize efficient outputs.The increased outputs are solved by linear programming using data envelopment analysis efficiency theories,wherein a new sample is introduced whose inputs are equal to the budget in the issue No.n ＋ 1 and outputs are forecasted by the GM（1,N） model.The shortcoming in the existing methods that the forecasted efficient outputs may be less than the possible actual outputs according to developing trends of input-output rate in the periods of pre-n is overcome.The new prediction method provides decision-makers with more decisionmaking information,and the initial conditions are easy to be given.

High-efficiency forming processes for complex thin-walled titanium alloys components: state-of-the-art and perspectives

Complex thin-walled titanium alloy components play a key role in the aircraft,aerospace and marine industries,offering the advantages of reduced weight and increased thermal resistance.The geometrical complexity,dimensional accuracy and in-service properties are essential to fulfill the high-performance standards required in new transportation systems,which brings new challenges to titanium alloy forming technologies.Traditional forming processes,such as superplastic forming or hot pressing,cannot meet all demands of modern applications due to their limited properties,low productivity and high cost.This has encouraged industry and research groups to develop novel high-efficiency forming processes.Hot gas pressure forming and hot stamping-quenching technologies have been developed for the manufacture of tubular and panel components,and are believed to be the cut-edge processes guaranteeing dimensional accuracy,microstructure and mechanical properties.This article intends to provide a critical review of high-efficiency titanium alloy forming processes,concentrating on latest investigations of controlling dimensional accuracy,microstructure and properties.The advantages and limitations of individual forming process are comprehensively analyzed,through which,future research trends of high-efficiency forming are identified including trends in process integration,processing window design,full cycle and multi-objective optimization.This review aims to provide a guide for researchers and process designers on the manufacture of thin-walled titanium alloy components whilst achieving high dimensional accuracy and satisfying performance properties with high efficiency and low cost.

Responses of Phosphorus Use Efficiency, Grain Yield, and Quality to Phosphorus Application Amount of Weak-Gluten Wheat

Phosphorus （P） is one of the most widely occurring nutrients for development and growth of wheat. In this study, the effects of P application amount on grain yield, protein content, and phosphorus use efficiency （PUE） were studied by agronomic management of P fertilizer on spring weak-gluten wheat （Triticum aestivum L.） grown under field conditions for 2 yr. The experiments were performed at five levels of P205 application amount, including 0, 72, 108, 144, and 180 kg ha-1. As a result, with increase in P fertilizer, grain yield, and P agricultural efficiency （AEp） increased in a quadratic equitation, but partial factor productivity of P （PFPp） decreased in a logarithmic eq. When 108 kg ha-1 P2Os was applied, the grain yield reached the highest level, but the protein content in gain was lower than 11.5%, a threshold for the protein content to evaluate weak-gluten wheat suitable for production of cake and biscuit. Yangmai 13 and Ningmai 9 could tolerate to higher P level of soils than Yangmai 9 that had more loss in grain yield when P fertilizer was over-applied. AEp had a concomitant relationship with grain yield and was a better descriptor for P use efficiency in the wheat. A high P use efficiency resulted in leaf area index （LAI）, increased chlorophyll content and photosynthetic rate, and stable acid phophatase （APase） activity to accumulate more dry matter after anthesis, which explained that the optimum P fertilizer increased grain yield and improved grain quality of weak-gluten wheat.

MAJOR－EFFICIENT SOLUTIONS AND WEAKLY MAJOR－EFFICIENT SOLUTIONS OF MULTIOBJECTIVE PROGRAMMING

In this papert the theory of major efficiency for multiobjective programmingis established.The major-efficient solutions and weakly major-efficient solutions of multiobjective programming given here are Pareto efficient solutions of the same multiobjectiveprogramming problem, but the converse is not true. In a ceratin sense , these solutionsare in fact better than any other Pareto efficient solutions. Some basic theorems whichcharacterize major-efficient solutions and weakly major-efficient solutions of multiobjective programming are stated and proved. Furthermore,the existence and some geometricproperties of these solutions are studied.

Weak WT_2-class of differential forms and weakly A-harmonic tensors

In this paper, we give the definition of weak WT2-class of differential forms, and then obtain its weak reverse Holder inequality. As an application, we give an alternative proof of the higher integrability result of weakly A-harmonic tensors due to B. Stroffolini.

Form invariance and conserved quantity for weakly nonholonomic system

The form invariance and the conserved quantity for a weakly nonholonomic system （WNS） are studied. The WNS is a nonholonomic system （NS） whose constraint equations contain a small parameter. The differential equations of motion of the system are established. The definition and the criterion of form invariance of the system are given. The conserved quantity deduced from the form invariance is obtained. Finally, an illustrative example is shown.

Form invariance and approximate conserved quantity of Appell equations for a weakly nonholonomic system

A weakly nonholonomic system is a nonholonomic system whose constraint equations contain a small parameter. The form invariance and the approximate conserved quantity of the Appell equations for a weakly nonholonomic system are studied. The Appell equations for the weakly nonholonomic system are established, and the definition and the criterion of form invariance of the system are given. The structural equation of form invariance for the weakly nonholonomic system and the approximate conserved quantity deduced from the form invariance of the system are obtained. Finally, an example is given to illustrate the application of the results.

A LEAST SQUARE BASED WEAK GALERKIN FINITE ELEMENT METHOD FOR SECOND ORDER ELLIPTIC EQUATIONS IN NON-DIVERGENCE FORM

This article is devoted to establishing a least square based weak Galerkin method for second order elliptic equations in non-divergence form using a discrete weak Hessian operator.Naturally,the resulting linear system is symmetric and positive definite,and thus the algorithm is easy to implement and analyze.Convergence analysis in the H2 equivalent norm is established on an arbitrary shape regular polygonal mesh.A superconvergence result is proved when the coefficient matrix is constant or piecewise constant.Numerical examples are performed which not only verify the theoretical results but also reveal some unexpected superconvergence phenomena.

Planar Weak Form Quadrature Beam Elements Based on Absolute Nodal Coordinate Formulation: A Structural Mechanics Approach

A planar nonlinear weak form quadrature beam element of arbitrary number of axial nodes is proposed on the basis of the absolute nodal coordinate formulation (ANCF). Elastic forces of the element are established through geometrically exact beam theory, resulting in good consistency with classical beam theory. Two examples with strong geometrical nonlinearity are presented to verify the effec-tiveness of the formulation.

Strong/weak limits and strong/weak differentials of multi-variable indeterminate forms. I: Deduction and geometric illustration

Strong and weak limits as well as strong and weak differentials of multi-variable indeterminate forms are discussed based on the thorough exploration of differentiation to solve the strong and weak limits and differentials of unitary indeterminate forms. The fruit of this work is going to be reported in three parts. The first part presents the standard analysis on this subject which supplements, systematizes and advances L. Hospital抯 principles on differential calculus by applying special ,general, and limit guaranteeing theories together with K(t) and XhK0 theories. The combination of theoretical analysis and geometric signification makes the derivation intuitional, visual and easy to perceive.

Is the“Weak Form”of CLT Being Adoptedin China ?

This paper, based on the hi sto rical background of CLT(communicative language teaching), mainly addresses the k ey issues concerning the weak form of CLT. This is an area few people have paid attention to in the past few years in China. Therefore, its main concepts and f e atures are discussed with relevance to literature and an empirical study on four novice teachers of English. Finally, the research shows that the weak form of CLT is being conducted in Chinese secondary schools.

弱光下锑基太阳电池的光谱响应与性能优化

锑基薄膜太阳电池因其制备方法简单,原材料丰富,光电性能稳定等优点而得到了快速发展。其中锑基吸光层材料(硫化锑、硫硒化锑、硒化锑)具有高吸收系数特点,因而在室内或者水下等弱光条件下具有相当大的应用潜力。通过构造两种衰减光谱以研究新型锑基薄膜太阳电池在弱光下的光电响应。首先通过厚度调节硒化锑太阳电池的吸光能力,发现当吸光层厚度较薄时,电池的光电转换效率存在较大差值;而当吸光层厚度过厚时,电池性能又因载流子复合的增大而降低。在吸光层厚度处于合适的0.4~1.2μm之间时,硒化锑太阳电池在长波衰减光谱和短波衰减光谱下都能获得高于16%的转换效率。然后通过硒含量调节锑基太阳电池的光谱吸收范围,发现长波衰减光谱下,锑基太阳电池的器件性能显著高于标准光谱,并且在20%~40%硒含量下能够获得最佳的转换效率。而在短波衰减光谱下,锑基太阳电池的最佳性能出现在硒含量为60%的情况下。因而在弱光条件下,锑基太阳电池的最佳硒含量需要通过具体的光谱特性确定。最后研究了两种衰减光谱下,硫化锑/硒化锑双结叠层太阳电池的光谱响应特性。发现在短波衰减光谱下,叠层太阳电池效率会随着总厚度的增加而增加。而在长波衰减光谱下,叠层太阳电池的最佳性能能够一直保持在较高水平。当叠层电池总厚度为2μm,且硫化锑顶电池厚度在0.5~1.2μm之间时,器件在两种衰减光谱下都能够实现光谱能量在两个子电池中的合理分配,使得叠层电池效率能够保持在20%以上。通过该研究对锑基太阳电池器件结构的合理设计,能够保证单结和双结器件在不同弱光条件下的高性能输出,为高环境适应性的锑基薄膜太阳电池的研发提供技术支持。

河南矿区高灰细泥煤泥水的絮凝沉降试验研究

目的随着采煤机械化程度的提高和重介质选煤工艺普及,入选浮煤泥中高灰细泥的含量逐渐增加。高灰细泥是影响煤泥水沉降效率的最直接因素,对煤泥水中的高灰细泥进行处理,直接关系着煤炭资源生产和水资源利用。针对河南矿区煤泥水具有高灰细泥的特性,方法通过设计正交试验测试不同种类的絮凝剂和搅拌速度对煤泥水的沉降率的影响及其之间的相互作用的效果,提高煤泥水沉降效率。结果结果表明:六偏磷酸钠与聚丙烯酰胺的分散性能及絮凝性能更优,搅拌速度、六偏磷酸钠用量、聚丙烯酰胺用量对高灰细泥煤泥水沉降率的影响程度依次减小,搅拌速度和聚丙烯酰胺用量之间的相互关系对沉降率影响最为显著;当六偏磷酸钠用量40.08 mg/L、聚丙烯酰胺用量5.75 mg/L、搅拌速度411.12 r/min,沉降率可达95.5%,沉降率提高的原因在于高灰细泥絮凝过程中絮团成球明显,絮凝剂的桥接作用可以使分散颗粒聚团并发展为球形,长条不规则颗粒明显减少,颗粒群粒形的改变有助于煤泥水的沉降,在一定搅拌速度下粒形保持较为规整,可增加沉降概率,使煤泥水得以有效沉降。结论通过改善煤泥水中颗粒的粒度粒形特性,可以有效提高河南矿区高灰细泥煤泥水的沉降效率。研究结果可为处理高灰细泥煤泥水提供理论支持和实践参考。

地铁入口空间布局对室内空气质量的影响研究

城市地铁地处繁华地区,结构封闭,周边环境污染源较多,室内易积累污染物。本研究重点关注地铁口空间布局对室外颗粒物进入的影响,在调研中选取地铁站入口方向、顶棚形态、入口高宽比3个形态指标作为影响因子,经过实测验证CFD模型的可行性后,选择RNG k-ε模型模拟不同风速下各地铁口形态的室内污染情况。结果表明:(1)侧向比正向入口颗粒拦截率高一倍;(2)入口高宽比小于1∶1时入口宽度越大,地铁站整体空气质量越好;(3)顶棚形态对室内颗粒物的消减排列为:斜顶>平顶>无顶;(4)地铁口空间形态对不同直径的颗粒拦截效果不同。形态设计可以改善站内颗粒物进入情况,通过空气对流、回流减少室外污染物的直接灌入。

医用X射线防护材料的研究进展

介绍了医用X射线与生物系统的相互作用机理及物理防护原理,分析了具有医用X射线屏蔽能力的柔性复合材料的研究进展。探讨了铅、铋、钨等防X射线功能颗粒及聚合物基材的性能特征,总结了涂层法、溶胶-凝胶法、纺丝法等成型方法的优缺点。研究表明,现有X射线防护材料在提升防护效果和使用便捷性方面具有重要意义,但面临性能优化和成本控制方面的挑战。未来研究应聚焦新型功能颗粒的开发、复合材料结构设计的优化及环保高效屏蔽材料的探索等方面,以进一步提升医用X射线防护材料的性能,拓宽其应用前景。

高功率激光水平辐照花岗岩致裂成孔特性及成孔能效评价

针对当前硬岩隧道钻爆法施工钻孔速度慢、钻头损耗大的工程难题,使用高功率激光水平辐照硬岩快速成孔替代传统PDC钻头钻孔,开展高功率激光水平辐照花岗岩成孔的可行性试验,分析高功率激光水平辐照花岗岩的致裂成孔特性;通过单轴压缩试验、扫描电子显微镜(SEM-EDS)和X射线衍射仪(XRD)衍射试验分析激光作用前后岩石的力学性能和微观物相演变;综合对比激光射孔与PDC钻头钻孔的破岩速度和比能。研究结果表明:岩石表面在激光持续辐照后形成“类爆炸坑”,产生的熔融物在重力作用下堆积在孔底,吸收了孔底处大部分的激光能量,抑制了孔底岩石的热裂反应;岩石的纵向破坏受重力影响导致上下孔壁熔融物分布不均匀,随着激光持续辐照,岩孔中心将不断向下偏离光斑入射点;经功率为4.5 kW的激光水平辐照10 s后,岩样的单轴抗压强度从63.31 MPa降低至42.36 MPa,其原因是钠长石分解引起岩样中黑云母的质量分数增加;功率为4.5 kW激光射孔的破岩速度较PDC钻头钻孔的破岩速度提高95.03%,比能增加15.3%,证明了高功率激光水平辐照硬岩成孔的有效性。

基于主动学习Kriging模型的改进一次可靠度方法

结构可靠度分析的一次可靠度方法在每一迭代中均涉及迭代点的函数值及梯度值计算,但后续迭代过程不能充分利用前期迭代过程中迭代点的计算结果,因此计算效率有待于进一步提升。考虑到迭代后期迭代点在局部区域内波动,若以已有迭代结果为基础建立代理模型进行迭代后期迭代点的函数值及梯度值计算将有助于改善一次可靠度方法的计算效率。为此,该文在将一次可靠度方法的迭代过程分为全局搜索阶段与局部搜索阶段的基础上,针对两个阶段分别采用不同的计算策略,即全局搜索阶段沿用已有一次可靠度方法的迭代过程,在局部搜索阶段则基于全局搜索阶段的迭代结果建立Kriging模型,并引入可评估Kriging模型在迭代点处精度的学习函数,实现局部搜索阶段迭代点的高效率计算,从而提出了具有更高计算效率的改进一次可靠度方法。数值算例和工程算例的计算结果表明建议方法在保持精度不变的情况下,可显著提高一次可靠度方法的计算效率。