Numerical solution of optimal control problem for a model of tumour growth with drug application

In this study, a combination of spectral and fixed point methods is used to solve an optimal control problem for a model of tumour growth. The growth of tumour is modelled using three first-order hyperbolic equations describing the evolution of cells and two second-order parabolic equations describing the diffusion of nutrient and drug concentration. In the optimal control problem, four control variables are employed to control the concentration of nutrient and drug on the boundary and inside the tumour. Since the problem is nonlinear, applying the fixed point method, in each step of iteration, the problem is changed to a linear one and the parabolic equations are solved using the spectral method. The convergence and stability of method are proven. Some examples are considered to illustrate the efficiency of method. Finally, some figures are provided to reflect the effects of control on the densities of tumourcells.     

Regional observability for distributed semi-linear hyperbolic systems

The objective of this paper is to study the notion of regional observability of hyperbolic semilinear systems. For the state reconstruction in a given subregion, we give a first approach which combines the extension of the HUM method and the fixed point techniques. The analytical case is then explored using sectorial property of the considered dynamic operator and converted to a fixed point problem. The two approaches lead to algorithms which are successfully implemented numerically and illustrated with examples and simulations.     

SYNTHESIS AND THERMAL INTERCONVERSION OF 5-FLUOROACENAPHTHYLENE BY FLASH VACUUM THERMOLYSIS

Abstract

The utility of high-temperature gas-phase cyclisation reactions for the synthesis of fluorosubstituted cyclopenta-fused polycyclic aromatic hydrocarbons (PAHs) was illustrated by the synthesis of 5-fluoroacenaphthylene by flash vacuum thermolysis (FVT) of 1-ethynyl-5-fluoronaphthalene.

The experimental results suggest that monofluorinated PAHs can be used as model compounds to study thermal interconversion of their parent PAHs since, with fluorine as a label; ¹⁹ F-NMR is a valuable tool to characterize complex mixtures.     

STRUCTURE OPTIMIZATION OF A CIRCULATING MOVING BED REACTOR

A stress distribution model for a liquid-solid circulating moving bed reactor that consists of a bottom reaction chamber, a top regeneration chamber, a coupling standpipe, a particle transportation system, and a bottom standpipe is established based on the equations of continuity and momentum balance. Simulations show that the stress concentration regions are at the bottom of the regeneration chamber and the coupling standpipe. To reduce the maximal stress and increase the operation flexibility in a reactor for the 2000-ton-per-year production of linear alkylbenzene, the regeneration chamber should have a low height-to-radius ratio (about 9), a suitable half-conical angle between 28° and 35°, and standpipe radius of about 0.05 m.     

Steady‐State and Dynamic Reactor Models for Hydrotreatment of Oil Fractions: A Review

The modeling of catalytic hydrotreatment reactors for petroleum fractions have been classified in several ways, for example steady‐state and dynamic, pseudohomogeneous, and heterogeneous, and so on. Depending on the system to be modeled, operating conditions and type of feedstock, these approaches could exhibit some advantages and disadvantages, wide scopes and limitations. In this review, the discussion about those modeling aspects, already published, is used to develop a generalized reactor model, which can be simplified in order to derive each single model previously reported. Some guides to estimate model parameters are also given.     

DRYING RESEARCH AND DEVELOPMENT IN CZECHOSLOVAKIA

This paper provides general information on drying R 6D activities in Czechoslovakia. This survey report lists the main topics in drying according to individual industrial sectors in which drying plays an important role. Drying R 6D carried out in Czechoslovak Universities is also cited. The paper includes an extensive list of references, mainly proceedings of national drying conferences, symposia, and meetings     

Design and Modeling of Plug Flow Fluid Bed Dryers

Plug flow fluid bed dryers (PFFBD) have been used for drying of particulate solids such as salts, ion exchange resins, grains, and a variety of other products. The present article describes the use of a mathematical model for the scale-up of lab-scale batch fluidization data to design an industrial-scale PFFBD. Axial dispersion theory was used in conjunction with the tanks-in-series model to describe the non-ideal flow. The model was implemented in Matlab 6.5 and it can be used for easily fluidizing particulate materials. The proposed model is capable of analyzing both the exponential falling rate and constant rate drying periods. The model predicts the required dryer dimensions for a given throughput and desired final moisture content. The model can also be used to study the effect of different process parameters such as solids feed rate, inlet air velocity, and temperature on the required dryer dimensions and it can also be used to predict the moisture and temperature profiles along the length of the PFFBD.     

某试验台保护系统分析

某厂试验台保护系统采用美国ROCKWELL公司的1756系列产品,设计方案运行可靠。本文分析了该保护系统的结构和主要功能,特别针对该系统的设计方案做了详细分析。     

浅议固定资产的管理

为科学提高固定资产的管理水平,发挥固定资产的最大使用效益,文章拟就固定资产管理各环节存在的问题及进一步加强固定资产管理的对策进行探讨。     

Numerical Simulation of Tube Erosion in a Bubbling Fluidized Bed with a Dense Tube Bundle

Tube erosion in a bubbling fluidized bed is numerically studied using the Eulerian‐Eulerian method coupled with a monolayer kinetic energy dissipation model. The hydrodynamical simulations are performed under conditions with three different superficial gas velocities. The time‐averaged bubble frequency and bubble rise velocity are calculated to characterize the bed hydrodynamics. The erosion rates of two target tubes are simulated and the influence of the bubble behaviors on erosion rates is evaluated. Compared with the experimental data in the literature, the bubble behaviors are well captured by the simulations. Good agreement between the calculated and measured erosion rates is also obtained for the two target tubes. The bubble behaviors around the tubes have direct impact on the tube erosion. Only small discrepancies in the calculated erosion rates are found when using different particle‐wall restitution coefficients and specularity coefficients.