Optimal Control of the Primary Drying Stage of Freeze Drying of Solutions in Vials Using Variational Calculus

The problem of operating freeze drying of pharmaceutical products in vials placed in trays of a freeze dryer to remove free water (in frozen state) at a minimum time was formulated as an optimal control problem. Two different types of freeze dryer designs were considered. In type I freeze dryer design, upper and lower plate temperatures were controlled together, while in type II freeze dryer design, upper and lower plate temperatures were controlled independently. The heat input to the material being dried and the drying chamber pressure were considered as control variables. Constraints were placed on the system state variables by the melting and scorch temperatures during primary drying stage. Necessary conditions of optimality for the primary drying stage of freeze drying process in vials are derived and presented. Furthermore, an approach for constructing the optimal control policies that would minimize the drying time for the primary drying stage was given. In order to analyze optimal control policy for the primary drying stage of the freeze-drying process in vials, a rigorous multi-dimensional unsteady state mathematical model was used. The theoretical approach presented in this work was applied in the freeze drying of skim milk. Significant reductions in the drying times of primary drying stage of freeze drying process in vials were obtained, as compared to the drying times obtained from conventional operational policies.     

A closed loop exponential feeding law: Invariance and global stability analysis

This article addresses the computation of invariant control laws [A. Fradkov, I. Miroshnik, V. Nikiforov, Nonlinear and Adaptive Control of Complex Systems, Kluwer, 1999] for fed-batch fermenters represented by two standard models. It will be shown how to derive partial state feedbacks that, assuming ideal conditions and perfect model, keep the specific growth rate μ constant provided the initial conditions are adequate. The invariant control law is the closed loop version of the exponential feeding already suggested in several references as shown later. The paper presents an analysis of invariance and a study of global stability within the framework of partial stability. That is, stability with respect to some of the state variables. This enables us to treat the case with Haldane-like or non-monotonous kinetics.     

瞬态非傅里叶导热效应判据的探讨

讨论了通用傅里叶导热定律的数学模型,推导了半无限大物体在第一类边界条件下的基于非傅里叶导热定律的双曲线型偏微分方程的解析解。通过分析非傅里叶导热定律在瞬态条件下温度分布的变化过程,提出了非傅里叶导热效应的瞬态判据以及非傅里叶导热的作用范围,对研究工程中瞬态导热问题(如激光处理,电子束处理等)有重要意义。     

濮城油田濮67块低渗凝析难动用气藏挖潜技术研究

濮67块具有埋藏深、物性条件差、储量难动用程度低等特点，目前气藏采出程度很低，开发效果差。通过对濮67块天然气储量再认识，落实了该块储量；通过对濮67块各砂组剩余天然气分布规律的研究，明确了剩余气的下步挖潜方向；并开展了配套的剩余天然气挖潜技术研究，通过在生产中应用，取得了较好的增产效果，提高了气藏的采收率。     

The Clausius inequality corrected for heat transfer involving radiation

The objective of this paper is to prove that the Clausius inequality must be re-stated to have general applicability for heat transfer involving radiative fluxes. The integrand (đQ/T) of the Clausius expression applies to heat conduction and convection, but does not hold for most radiative transfer scenarios, with the exception of reversible infinitesimal net blackbody radiation transfer. In other cases involving radiative transfer, the equality holds for a cycle even though irreversible heat addition by radiative transfer occurs. This is without the erroneous presumption of entropy destruction anywhere in the cycle. Thus, the Clausius inequality indicates reversibility for a cycle that includes an irreversible process. Further, in some radiative cases the quantity đQ/T, where T is the boundary temperature, is not the entropy transfer at the system boundary, and in fact, primarily represents entropy production within the system. It is also clear that in another case considered, the quantity đQ/T had no physical meaning whatsoever. Consequently, the Clausius expression has been re-stated so that it is applicable to cycles with processes involving any form of heat transfer. A new integrand (đQ_cc/T + đS_Net,Rad) is presented, allowing the Clausius inequality to generally apply to all heat transfer scenarios. The work in this paper emphasizes the need to re-state other fundamental equations allowing applicability to all heat transfer processes, and draws attention to the unique character of radiative entropy calculations.     

Optimal ensemble construction via meta-evolutionary ensembles

In this paper, we propose a meta-evolutionary approach to improve on the performance of individual classifiers. In the proposed system, individual classifiers evolve, competing to correctly classify test points, and are given extra rewards for getting difficult points right. Ensembles consisting of multiple classifiers also compete for member classifiers, and are rewarded based on their predictive performance. In this way we aim to build small-sized optimal ensembles rather than form large-sized ensembles of individually-optimized classifiers. Experimental results on 15 data sets suggest that our algorithms can generate ensembles that are more effective than single classifiers and traditional ensemble methods.     

碾压混凝土穿透型诱导缝不同扩展阶段的强度指标试验研究

在不同削弱度碾压混凝土轴拉试件的穿透型诱导缝周围粘贴了应变片，得到在不同应力状态下诱导缝应变发展规律为：在加载初期，离缝端不同距离的应变发展较为均匀，数值上相差不突出；随着荷载的增加，应变开始出现不均匀发展，离缝端越远，应变变化越缓慢；当接近最大荷载的阶段，缝端应变急速发展，试件瞬间断裂。应变从均匀发展变为不均匀发展，实质上隐含了诱导缝起裂、稳定发展、失稳断裂的整个过程，针对这一试验现象，结合断裂力学理论，建立了诱导缝不同开裂阶段的远场温度应力强度指标模型。     

Coupling of free surface and groundwater flows

In this paper we present some preliminary results about the coupling of shallow water equations for free surface flows and Darcy equation for groundwater flows. A suitable set of interface conditions is discussed: the Beavers and Joseph formula for the bottom stress is used. An iterative algorithm to solve the coupled problem is proposed and some numerical results are presented.     

一种复合制导导弹的导航滤波器设计

研究了一种中制导段采用雷达修正的遥控制导方式和末制导段采用捷联式自寻的导引头的自导引制导方式的捷联式复合制导的中远程战术导弹的导航滤波问题，考虑到目标的大机动性和模型的非线性，基于最佳估计理论中的广义卡尔曼滤波理论，建立了通用导航滤波方程，仿真计算与仿真结果表明所做设计是合理和有效的。     

石油企业办社会的“悖理行为”辨疑

企业办社会虽与市场经济的客观要求相悖，但石油企业大量办社会的事实仍揭示了所具备的理性面。认为国家作为不受所有者监督的代理者对石油企业的要求，石油企业的行业特性以及在传统体制下长期运作所成的定热是石油企业办社会的主要原因。