Numerically optimal design for the system with coupled complex transport phenomena-application to the Submerged Entry<Emphasis Type="Italic">Nozzle</Emphasis> in continuous slab caster

This study presents a simple and robust algorithm for the optimal design of the system with coupled complex transport phenomena: the transport phenomena comprise fluid flow, heat and mass transfer. The (1+1)-Evolution Strategy method is adopted as the optimization method. In order to analyze the transport phenomena in the complex geometry generated during the optimization procedure, thefinite volume method with a boundary fitted curvilinear coordinate system is used. To confirm the validity of the present method, the optimal design for the inner shape of the simplified two-dimensionalSubmerged Entry Nozzle in the continuous slab caster is conducted. It is shown that the resulting design of the nozzle is consistent with the purpose and constraints of the design.     

Soft and Hard Adhesion

The force needed to pull a cylindrical stud from a soft elastomeric film depends on their elastic and geometric properties. For a rigid stud and a thick elastomeric film, the pull-off stress (σ) depends on the elastic modulus (E) of the film and the radius (a) of the stud as σ ∼ (E/a)^1/2 (soft adhesion). However, when the film is very thin, the pull-off stress is significantly higher than the case with thick films, and its value depends on the elastic modulus and the thickness (h) of the film as σ ∼ (E/h)^1/2 (hard adhesion). Here, we study the pull-off behavior of a soft cylindrical stud, one flat end of which is coated with a high modulus thin baseplate. As the flexural rigidity of this baseplate is varied, we observe the transition between the two types of adhesion. We present a simple physical interpretation of the problem, which could be of value in understanding various biofouling and adhesive situations.     

Nafcillin release from poly(acrylic acid–co–methyl methacrylate) hydrogels

Summary Copolymeric poly(acrylic acid-co-methyl methacrylate) hydrogels for three different compositions: (90/10), (80/20) and (60/40), have been studied. Drug release has been examined as a function of the hydrogel composition by HPLC (High Pressure Liquid Cromatography). The release experiments were carried out at 37 °C. The fraction of available drug release was linear in t^1/2. The values of the diffusional coefficient (0.50<n<1.0) indicate that the nafcillin release mechanism from the hydrogels in study is non-Fickian. The diffusion coefficients for this drug release have been calculated. The molecular diffusion of nafcillin through hydrogels is controlled by the swelling.     

Calculated effect of pulsed pheromone release on range of attraction

In order to assess the possible function of pulsed release of windborne pheromones, calculations were performed to predict the concentration pattern downwind of the source. Two patterns of pulsed releases (sinusoidal and instantaneous) were compared to a constant release pattern. In all three cases, the average rate of release was the same. Assuming the receiving animal needs only a momentary exposure to concentrations above threshold to respond, it is clear that sinusoidal release has a greater distance of detection than constant release and that instantaneous release is even better. The relative magnitude of the increase in range of detection depends on the ratio of average release rate to threshold concentration. Pulsed releases have a greater advantage when the threshold is high and the range of attraction is inherently short. Under these conditions, sinusoidal release can double the range of attraction and instantaneous release can increase it 10-fold. In contrast, with a low threshold and consequent long range of attraction, the pulsed patterns are lost and the increase in range is insignificant. Several testable predictions are derived from the hypothesis that the primary function of pulsed release is to extend the range and time over which a given quantity of pheromone can act.     

Numerical Analysis of the Constrained Blister Test

The constrained blister test is investigated through finite element analysis to determine the applicabilities and the limitations of the new technique. Numerical results confirm that the strain energy release rate asymptotically approaches a constant value. These results also show that the test technique and the approximate solution for strain energy release rate are applicable for some practical cases.     

Averaged control

We analyze the problem of controlling parameter-dependent systems. We introduce the notion of averaged control according to which the quantity of interest is the average of the states with respect to the parameter.First we consider the problem of controllability for linear finite-dimensional systems and show that a necessary and sufficient condition for averaged controllability is an averaged rank condition, in the spirit of the classical rank condition for linear control systems, but involving averaged momenta of any order of the matrices generating the dynamics and representing the control action.We also describe some open problems and directions of possible research, in particular on the average controllability of evolution partial differential equations. In this context we analyze also the averaged version of a classical optimal control problem for a parameter dependent elliptic equation and derive the corresponding optimality system.     

主旋翼升力和机身姿态受限的模型直升机非线性控制（英文）

A nonlinear control is proposed for trajectory tracking of a 6-DOF model-scaled helicopter with constraints on main rotor thrust and fuselage attitude. In the procedure of control design, the mathematical model of helicopter is simplified into three subsystems: altitude subsystem, longitudinal-lateral subsystem and attitude subsystem. The proposed control is developed by combining the sub-controls for the corresponding subsystems. The sub-controls for altitude subsystem and longitudinal-lateral subsystem are designed with hyperbolic tangent functions to satisfy the constraints; the sub-control for attitude subsystem is based on backstepping technique such that fuselage attitude tracks the virtual control for longitudinallateral subsystem. It is proved theoretically that tracking errors are ultimately bounded, and control constraints are satisfied.Performances of the proposed controller are demonstrated by simulation results.     

吸附型固载二氧化氯释放特性的测定与应用研究

通过实验研究 ,定义并测定了吸附型固载二氧化氯的释放特性参数 ,并以临界释放速率UC =0 .0 0 5μg/(h·cm3)作为释放终点 ,将其分为长效、快速和中速释放 3种类型。长效型释放速率峰值Umax <2 0 μg/(h·cm3) ,峰值时间τmax >360h ,有效释放时间τcs >60d ;快速释放型Umax >60 μg/(h·cm3) ,τmax <1 2h ,τcs <7d ;中速释放型则处于两者之间。讨论了固载二氧化氯释放特性的控制方法和不同类型产品的适用范围 ,为产品释放特性的定量研究和应用开发提供了依据。     

Heat-release mechanism in ammonium dinitramide flame

To verify the adequacy of various models of heat release in ammonium dinitramide flame to real processes, chemical processes in products of thermal decomposition at a pressure of 10 torr and in ammonium dinitramide [ADN; NH₄N(NO₂)₂] flame at a pressure of 0.4 to 60 atm are numerically simulated. The calculations are performed on the basis of a detailed kinetic mechanism and boundary conditions correlated with experimental data, thermodynamic properties, and chemical composition of ADN. The kinetic mechanism includes submechanisms that describe high-temperature chemical processes in NH₃/N₂O/NO/NO₂/HNO₂/HNO₃ and NH₃/HN(NO₂)₂ mixtures, and the global stages of aerosol decomposition. Based on calculated and experimental data, the role of dinitraminic acid HN(NO₂)₂, aerosols, and ADN vapor in heat release in the ADN flame zone adjacent to the burning surface is estimated. The calculations predict that the main source of heat release in the cold flame zone at p ≥ 3 atm is dinitraminic acid incoming through the channel of dissociative evaporation ADN_liq → NH₃ + HN(NO₂)₂ from the burning surface. In the high-temperature flame zone, heat release is caused by the reaction that occurs in the NH₃/N₂O/NO/NO₂/HNO₂/HNO₃ mixture. At moderate pressures, the high-temperature and low-temperature zones are separated by an induction zone. The stage governing production of the OH radical, which plays an important role in combustion, in the induction zone is the reaction HNO₃ + M → OH + NO₂ + M. Because of a high activation energy of the stage, small temperature perturbations in the induction zone at low pressures lead to a finite change in the stand-off distance between the high-temperature flame zone and the burning surface. Therefore, small temperature perturbations in the induction zone, which are caused by admixtures in the sample or by heat transfer between the reacting gas and the ambient medium, may be responsible for disagreement between various experimental data and between experimental and calculated data on the stand-off distance between the high-temperature flame zone and the burning surface. In numerical calculations, the position of the high-temperature zone is effectively controlled by varying rate constants of elementary stages within admissible limits. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 64–76, September–October, 2007.     

An integrated job release and scheduling approach on parallel machines: An application in electric wire-harness industry

This paper presents a new job release (JR) and scheduling methodology for one-stage parallel machines where sequence dependent setup times exist. A decision support system (DSS) based on job release is developed in order to enable the application of the methodology. First, mathematical programming models for both job release and job scheduling are devised. Then, due to the NP-hard nature of the problems, heuristics are proposed. As for the interaction between JR and scheduling, job scheduling is integrated with job release for the proposed heuristic solutions so that the capacity achievement provided by scheduling can be utilized for job release. In brief, product design characteristics oriented scheduling affects JR in the proposed approach. Moreover, value stream mapping (VSM) approach is used with the aim of stating the effect of the proposed methodology. Furthermore, the presented methodology was applied in a real life electric wire-harness production system. The application, based on 120-day production data, revealed that the proposed methodology provided 25% decrease in in-plant manufacturing lead time.