三种复杂性测度在气固流化床压力脉动中的应用

首次将三种复杂性测度－复杂性C2，涨落复杂性Cf，算法复杂性C(n)－同时应用于气固流化床压力脉动信号的分析之中，研究了不同表现气速，颗粒体系以及静床高等操作条件三种复杂性测度的变化规律以及对气固两相不同的表征能力。研究结果表明，三种复杂性测度均能敏感地指示出流型的变化，并且在不同的操作条件下呈现一定的规律性；尤其是三种复杂性测度将气固两相分开表征的能力，为研究气固两相内在动力学特性提供了新的思路。     

SC(NH2)2-H2O2-Cu2+-OH-封闭体系非线性动力学研究

利用微量量热仪测定体系热功率随时间的改变。对于SC(NH2)2-H2O2-Cu2 -OH-封闭体系,测定了不同浓度,不同温度下,体系的单峰振荡行为,得到了不同温度,不同浓度下的振荡周期,并由此计算出振荡反应的表观活化能和反应级数。并得到下列关系:1t∝c-0.3355     

Spatial simulations in systems biology: from molecules to cells

Cells are highly organized objects containing millions of molecules. Each biomolecule has a specific shape in order to interact with others in the complex machinery. Spatial dynamics emerge in this system on length and time scales which can not yet be modeled with full atomic detail. This review gives an overview of methods which can be used to simulate the complete cell at least with molecular detail, especially Brownian dynamics simulations. Such simulations require correct implementation of the diffusion-controlled reaction scheme occurring on this level. Implementations and applications of spatial simulations are presented, and finally it is discussed how the atomic level can be included for instance in multi-scale simulation methods.     

盐酸奥布卡因的合成

以3-羟基-4-硝基苯甲酸(2)为原料,经酯化制得3-羟基-4-硝基苯甲酸乙酯(3),3与1-溴丁烷成醚后,再经水解脱保护基制得关键中间体3-丁氧基-4-硝基苯甲酸(5)。另用2-二乙胺基乙醇(6)经氯化亚砜氯化制得2-(二乙胺基)氯乙烷盐酸盐(7)。5与7经缩合制得3-丁氧基-4-硝基苯甲酸2-(二乙胺基)乙酯(8)后成盐酸盐9,最后经Pd/C催化氢化还原硝基即可得到盐酸奥布卡因(1),总收率为67.2%(以2计)。     

Convergence depth control for interior point methods

For practical applications, optimization algorithms may converge to the optimal solution unreasonably slowly because of factors such as the poor scaling, ill‐conditioning, errors in calculation, and so on. Most improvements during the optimization procedure are made within a small part of the total computation time. To relieve the heavy computational burden, it is necessary to balance the calculation accuracy and computation cost. The traditional termination criteria based on the Karush‐Kuhn‐Tucker conditions cannot appropriately meet this requirement. Convergence depth control (CDC) strategy for Reduced Hessian Successive Quadratic Programming (RSQP) was presented as an alternative measure in a previous study. This work incorporates interior point methods with the modified CDC strategy, which was tested through AMPL interface and Aspen Open Solvers interface. Related properties are proved. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

具有麻醉功能的医用纤维材料的结构性能表征

纤维材料作为药物载体比其它聚合物材料具有更好的优越性,麻醉性生物活性纤维所要解决的主要问题是延长局麻药的麻醉作用时间。采用熔融纺丝的方法制备出了具有麻醉作用的生物活性纤维材料,并通过扫描电子显微镜(SEM)、差热分析(DSC)、红外光谱分析(IR)等手段对这种纤维材料的结构和性能进行了表征,并对纤维中局麻药的释放速率进行了测定,以证明这种纤维确实能够达到释放局麻药的效果。     

Theoretical investigation of steady state multiplicities in solid oxide fuel cells*

The nonlinear steady state behaviour of solid oxide fuel cells (SOFCs) is investigated. It is found that the temperature dependence of the electrolyte conductivity has a very strong influence on the occurrence of multiple steady states, instabilities and the formation of hot spots. Two correlations from the literature for the electrolyte conductivity are studied in a lumped model and in a 1D spatially distributed model of a SOFC. The cases of galvanostatic operation, potentiostatic operation, and operation under a constant ohmic load are considered. The lumped model possesses a unique steady state under galvanostatic operation and up to three steady states under potentiostatic operation or under constant load. In the distributed model, three steady states may coexist under galvanostatic operation and up to five under potentiostatic operation. Paper originally given at the CHISA Congress, Prague, August 2004.     

环氧树脂固化深度的非线性超声检测

摘要：环氧树脂的物理和力学性能、耐腐蚀性、易粘接性、绝缘性、密封性等性能与其固化深度密切相关。为满足表征环氧树脂固化深度的需求,研究了一种测量环氧树脂固化深度的非线性超声检测系统,获取了不同固化时间下的超声时域波形,验证了信号中的非线性来自于粘接试件。为了提取表征固化深度的非线性信息,分别基于二次回波信号的峰-峰值和Hilbert-Huang变换(HHT)对时域信号进行了分析。研究结果表明,经HHT处理后的三次谐波相对幅值能对固化过程中的各个相变点进行有效表征,这对改进该类环氧树脂的固化工艺以及固化过程的更好控制具有一定指导意义。     

基于收敛深度控制的多元混合非线性规划算法

随着对象模型描述的系统性和完整性的提高,过程优化问题的复杂程度逐步增加,对优化算法的性能提出了更高的要求。现有的非线性规划算法在求解性能上各有优劣,本文提出了一种基于收敛深度控制的多元混合非线性规划算法,将各个非线性规划算法视为元算法,利用收敛深度来控制这些元算法之间的相互协作,更好地发挥元算法各自的优势,从而提高求解大规模复杂优化问题的能力。采用空分系统的数据校正问题以及脱丙烷塔和脱丁烷塔联塔系统的优化问题对多元混合算法进行了测试,数值结果表明相比各个单独的非线性规划算法而言,多元混合算法具有更好的求解性能。     

钠化焙烧转炉钒渣粉体分形生长的演化行为

转炉钒渣焙烧提钒技术效率低,过程涉及化学反应、传递及相变过程,蕴含物相分形生长的动力学行为。对钒渣分形变化规律的研究有助于促进钒的定向转化,进而对工业提钒具有指导意义。根据金相电镜图,使用“周长-面积法”对不同焙烧条件下钒渣粉体分形维数进行计算,得到分形维数变化与物相转化的规律。结果表明,焙烧前硅相、钒相紧密包裹,分形维数数值为1.60~2.00;加入碳酸钠焙烧后尖晶石破坏,钒相逐渐分离,使分形维数小于1.20;随着钠盐加入量的增加,物相分形维数逐渐下降;二次焙烧后,稳定的钒酸钠生成,体系趋于稳定,使得分形维数进一步下降为1.10~1.20。     

均四甲苯静态结晶动力学研究

均四甲苯与其同分异构体沸点相近、熔点相差较大,不适合采用精馏精制,而宜采用熔融结晶方法进行分离。在考虑固液相界面温度随冷剂温度变化的前提下,采用解析迭代法研究均四甲苯熔融结晶动力学并设计实验进行验证。利用非线性最小二乘法对等温实验数据进行拟合得到不同冷剂温度下的组合动力学参数,并通过多项式拟合得到了组合动力学参数随冷剂温度的变化关系。将其应用于模拟非等温结晶过程的晶体生长,计算结果与实验数据基本吻合,表明该模型能很好地预测晶层生长过程。     

双层撞击流混合器浓度时间序列的多重分形分析

利用平面激光诱导荧光技术(PLIF)对双层撞击流混合器的浓度场进行了实验测量,获得了不同径向位置处的浓度时间序列,通过多重分形去趋势波动方法(MF-DFA)研究了浓度时间序列中的多重分形特性,得到不同喷嘴间距和射流雷诺数下的多重分形谱,实现了流场特性的定量表征。结果表明,随着喷嘴间距增大,浓度时间序列的奇异性减弱,随着射流雷诺数增大,浓度时间序列的奇异性增强,喷嘴间距对浓度时间序列奇异性的影响比射流雷诺数更为显著。浓度信号的奇异性越强,流体粒子脉动越剧烈,混合效果越强,喷嘴间距对混合的促进作用大于射流雷诺数。通过分析多重分形谱参数(Δα, αmin, α0)随径向位置的变化规律得出了流型的转变区域,并将双层撞击流混合器由撞击中心处向下分为二次撞击区、涡旋区、一次撞击区。浓度信号的奇异性二次撞击区>一次撞击区>涡旋区,对混合的促进作用二次撞击区>一次撞击区>涡旋区。研究结果为更深入地揭示撞击流混合器内部流动模式和撞击流复杂无序的流动机理提供了理论依据。     

干气密封系统轴向非线性动力稳定性

建立了轴向振动下气膜-密封环系统流固耦合动力学模型,应用微扰法和龙格-库塔法求解振动方程,分析失稳点振动非线性动力学行为。结果表明,在静态优化出的螺旋角范围(70～80°)内,存在着失稳点域,并在特定的螺旋槽结构参数范围内产生了混沌运动,通过选择合理的螺旋槽结构参数可以控制混沌。改变工况,虽其振幅发生了变化,但失稳点的螺旋角数值不变。得到控制系统稳定运行的结构参数区域,计算结果为干气密封的动态优化设计提供指导。     

几何结构对圆内开缝圆自然对流的影响

采用SIMPLE算法,对不同几何结构圆内开缝圆自然对流换热进行数值模拟,研究了开缝度、半径比改变对流动换热的影响。结果表明,在相同条件下计算数值结果与已有的实验结果吻合良好;把内圆开缝可以强化换热,但并非开缝度越大换热越好;半径比对换热效果产生影响,表现为半径比越小,环形空间越窄,换热效果越差。随着半径比的增大,K_eq显著增加,当半径比超过2.0时,K_eq基本保持不变。     

大流量调节阀瞬态模型建模方法研究

以循环发电工程的大流量调节阀为例,对建立调节阀瞬态模型的方法进行研究。通过对大流量调节阀建立关于压力和开度的试验模型,并对其进行相应的流体动力学数值计算,根据数值试验的结果,利用多元非线性回归的数学方法建立大流量调节阀基于压力和开度的瞬态模型,经过F检验法和复相关系数检验法的检验,证明了瞬态模型的有效性。     

Modeling heterogeneous bacterial populations exposed to antibiotics: The logistic‐dynamics case

In typical in vitro tests for clinical use or development of antibiotics, samples from a bacterial population are exposed to an antibiotic at various concentrations. The resulting data can then be used to build a mathematical model suitable for dosing regimen design or for further development. For bacterial populations that include resistant subpopulations—an issue that has reached alarming proportions—building such a model is challenging. In prior work, we developed a related modeling framework for such heterogeneous bacterial populations following linear dynamics when exposed to an antibiotic. We extend this framework to the case of logistic dynamics, common among strongly resistant bacterial strains. Explicit formulas are developed that can be easily used in parameter estimation and subsequent dosing regimen design under realistic pharmacokinetic conditions. A case study using experimental data from the effect of an antibiotic on a gram‐negative bacterial population exemplifies the usefulness of the proposed approach. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2385–2393, 2015     

Estimation of Nonparametric Autoregressive Time Series Models Under Dynamical Constraints

Abstract. A method is introduced to estimate nonparametric autoregressive models under the additional constraint that its regression function has a stable cycle. It is based on a penalty approach that chooses a series expansion approximation taking into account both goodness‐of‐fit and fulfillment of the constraint. Consistency of the proposed estimator is obtained under general hypothesis. Feasibility and effective performance of the introduced method are studied through simulated examples and electro‐encephalographic data collected from a subject suffering from epilepsy.     

Carborane‐Derived Local Anesthetics are Isomer Dependent

Clinically there is a need for local anesthetics with a greater specificity of action on target cells and longer duration. We have synthesized a series of local anesthetic derivatives we call boronicaines in which the aromatic phenyl ring of lidocaine was replaced with ortho‐, meta‐, C,C’‐dimethyl meta‐ and para‐carborane clusters. The boronicaine derivatives were tested for their analgesic activity and compared with lidocaine using standard procedures in mice following a plantar injection. The compounds differed in their analgesic activity in the following order: ortho‐carborane = C,C’‐dimethyl meta‐carborane > para‐carborane > lidocaine > meta‐carborane derivative. Both ortho‐boronicaine and C,C’‐dimethyl meta‐boronicaine had longer durations of analgesia than lidocaine. Differences in analgesic efficacies are rationalized by variations in chemical structure and protein binding characteristics.