Superconvergence of finite volume methods for the Stokes equations

A general superconvergence result of finite volume method for the Stokes equations is obtained by using a L² projection post‐processing technique. This superconvergence result can be applied to different finite volume methods and to general quasi‐uniform meshes.© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2009     

基于关键链方法的多项目共享人力资源均衡问题及其遗传算法

通过对多项目管理瓶颈的分析,结合关键链方法,设置了瓶颈缓冲,建立了基于关键链方法的多项目管理,为多项目管理提供了一种新的管理方法.将基于关键链方法的多项目管理方法应用于并行多项目共享人力资源冲突管理,建立了基于遗传算法的多项目共享人力资源均衡模型,为缓解多项目共享人力资源供求矛盾提供了一种具体的量化管理方法,并进行了算例分析,证明了模型的有效性、实用性.     

DBD在原子光谱领域内的应用进展

介质阻挡放电因其体积小、结构简单、能耗低、工作温度低、样品解离/激发能力强等显著特点,特别适合于分析仪器的微型化和便携化。目前,基于介质阻挡放电的原子化器或激发光源已成功应用于原子吸收光谱仪、原子荧光光谱仪和原子发射光谱仪中,促进了小型化原子光谱仪器的发展。总结了介质阻挡放电技术在原子光谱领域内的研究进展,着重阐述了介质阻挡放电-原子发射光谱系统在不同进样方式下的应用情况,分析了每种进样方式的优缺点。本文还对介质阻挡放电技术在诱导蒸气发生、固体直接进样方面的新应用方向进行了评述。虽然介质阻挡放电技术已在原子光谱领域内得到广泛的应用,但其反应机理仍然不明确,制约了其后续的拓展研究。     

Hereditary effects of exponentially damped oscillators with past histories

This paper presents hereditary effects of exponentially damped oscillators with past histories. Unlike the classical viscously damped oscillators, the nonviscously damped ones involve damping forces which depend on time-histories of vibrating motions via convolution integrals. As a result, equations of motion of such systems are a set of coupled second-order Volterra integro-differential equations. In this work, initial value problems for the integro-differential equations are revisited. The initial conditions should contain time-histories of vibrating motions. Then, initialization response of exponentially damped oscillators is obtained. It is used to characterize the hereditary effects on the dynamic response. At last, stability of initialization response is proved from the theoretical viewpoint and verified by numerical simulations. This reveals that the hereditary effects gradually recede with increasing of time.     

Relationship between mass discharge rate and granular temperature of silo flow with variance of outlets

A lower granular temperature zone near the orifice in silos was found by speckle visibility spectroscopy technology.Surprisingly,the values of granular temperat...     

利用高光谱扫描技术检测小麦叶片叶绿素含量

利用高光谱扫描技术对小麦叶片进行无损检测试验,探索精确测定小麦叶绿素含量的方法,为农作物生长状况、植物病理诊断等提供科学依据。研究选取90个样本作为校正集,30个样本作为预测集,获取叶片的高光谱反射图像,同时用传统的分光光度计方法测定其叶绿素含量。选取波长491～887 nm范围光谱,用多元散射校正、一阶导数、二阶导数3种方法处理,利用偏最小二乘法和逐步线性回归法分别建立了小麦叶片叶绿素含量与光谱信号间的数学模型。研究发现多元散射校正(MSC)结合二阶导数光谱的多元线性回归(SMLR)模型的效果较优,模型校正集和预测集决定系数分别为0.82和0.79,校正均方根误差和预测均方根误差分别为0.69和0.71。研究结果表明可以利用高光谱扫描技术检测小麦叶片叶绿素含量。     

$\alpha$-可分解4-圈系统

An m-cycle system of order v and index λ, denoted by m-CS（v,λ）, is a collection of cycles of length m whose edges partition the edges of λKv. An m-CS（v,λ） is α-resolvable if its cycles can be partitioned into classes such that each point of the design occurs in precisely α cycles in each class. The necessary conditions for the existence of such a design are m｜λv（v-1）/2,2｜λ（v -1）,m｜αv,α｜λ（v-1）/2. It is shown in this paper that these conditions are also sufficient when m = 4.     

Cubic Mesoporous Titanium Phosphonates with Multifunctionality

Cubic mesoporous titanium phosphonate materials with bridged organic groups inside the framework were synthesized by means of a one‐pot hydrothermal autoclaving process, with the assistance of cationic surfactant cetyltrimethylammonium bromide. 1‐Hydroxyethylidene‐1,1‐diphosphonic acid was used as the coupling molecule. A typical cubic mesophase with surface area of 1052 m² g^?1 and pore size of 2.6 nm was confirmed by XRD, TEM, and N₂ sorption analysis. The organophosphonate groups were homogeneously incorporated in the network of the mesoporous solids, as revealed by FTIR and magic‐angle spinning (MAS) NMR spectroscopy, and thermogravimetry and differential scanning calorimetry (TG‐DSC) measurements. The synthesized hydroxyethylidene‐bridged cubic mesoporous titanium phosphonates proved to be thermally stable up to 350 °C, with a well‐preserved hybrid framework and cubic mesoporous architecture. The obtained cubic mesophase could be transformed into a hexagonal mesophase by simply adjusting the molar ratios of the added raw materials, namely, a Ti/P molar ratio of 1:4 and a CTAB/Ti molar ratio of 1.9–2.3 for the cubic phase and Ti/P molar ratio of 3:4 and CTAB/Ti molar ratio of 0.1–0.4 for the hexagonal phase. The cubic hybrid materials could be used as efficient photocatalysts for the photodegradation of rhodamine B. Moreover, they were also used for adsorption of CO₂ and heavy metal ions and exhibited a significant capture amount of around 1.0 mmol g^?1 for CO₂ molecules at 35 °C and high adsorption capacity of 28.5 μmol g^?1 for Cu²⁺ ions with good reusability, which demonstrated their promising potential in environmental remediation.     

One‐ and Two‐Dimensional PbII Complexes Constructed from N‐Donor Chelating Ligands with Extended π‐System and Organic Dicarboxylates

Two new coordination polymers [Pb(TIP)(1,3‐bdc)]_n ( 1 ) and [Pb(Dpq)(fum)]_n ( 2 ) (TIP = 2‐(2‐thienyl)imidazo[4,5‐f]1,10‐phenanthroline, Dpq = dipyrido[3,2‐d:2′,3′‐f]quinoxaline, 1,3‐H₂bdc = benzene‐1,3‐dicarboxylic acid, fum = fumaric acid) were synthesized by hydrothermal reactions and were characterized by elemental analyses, IR spectroscopy and single‐crystal X‐ray diffraction. Complex 1 is a one‐dimensional (1D) chain, which is bridged by 1,3‐bdc ligands. This is further extended into a three‐dimensional (3D) supramolecular structure by hydrogen bonding interactions. Compound 2 exhibits a two‐dimensional (2D) network structure, which is further stacked by π–π interactions to form a 3D supramolecular framework. The most important feature of these two complexes is that the N‐donor ligands with an extended π‐system play a crucial role in the formation and stabilization of the final supramolecular frameworks. Moreover, the fluorescence property of complex 1 was also investigated in the solid state at room temperature.     

带有Holling IV功能反应的离散半比率依赖捕食-食饵系统的持久性和全局吸引性

In this paper, we investigate a discrete semi-ratio dependent predator-prey system with Holling IV type functional response. For general nonautonomous case, sufficient conditions which ensure the permanence and the global stability of the system are obtained. Meanwhile, we discuss the existence of the positive periodic solution and global stability of the system.