Issues in nonlinear stochastic grey box identification

Grey box identification refers to the practice of identifying dynamical systems in model structures exploiting partial prior information. This contribution reviews a method for stochastic grey box identification and surveys experiences and lessons of applying it to a number of industrial processes. Issues to be addressed include advantages and costs of introducing stochastics into the model, the question of what contribution must be expected from the model designer as opposed to what can be formalized in computer algorithms, and an outlook on future plans to resolve present shortcomings.     

Two Isomers of C60F48: Computed Inter-isomeric Equilibrium

C₆₀F₄₈ has been known to exist in two isomeric forms of D₃ and S₆ symmetries. However, the quantum-chemical calculations have not agreed on their stability order though a near-isoenergetic picture is otherwise always encountered. In order to clarify the situation, the entropy effects are evaluated for synthetic temperatures of about 500K. The entropy evaluations suggest that the D₃ isomer should be more stable in the potential energy by 2.05-2.55 kcal/mol (to which term the ab initio data are closer than the semiempirical ones).     

轻便型γ能谱测井仪几个关键技术问题的探讨

为研制性能好，功能强，微机化学程度高的轻便型γ能谱测井仪，针对非油气测井工作的井口径小（〈φ６０ｍｍ）井身浅（〈１０００ｍ）等特点，探讨了γ能谱测井仪的轻便化，测量精度，信号传输技术，稳谱技术及微机化等关键技术问题。     

储层石蜡沉积预测技术研究与应用

在油田开发过程中 ,由于油藏温度、压力等条件的变化 ,高含蜡原油在近井带容易产生石蜡沉积 ,堵塞地层孔隙或裂缝 ,严重影响油田开采 ,尤其对于低渗油田 ,伤害特别严重。文中应用理想溶液理论、质量守恒和能量守恒等基本原理 ,建立更符合油田实际情况的油藏中石蜡沉积预测数学模型 ,开发一套方便实用的油藏中石蜡沉积预测软件系统FPOS1 0。在此基础上 ,应用室内实验数据和现场数据对吉林新民油田油井石蜡沉积情况进行预测和现场拟合 ,确定新民油田临界石蜡沉积半径为 2 5m ,快速、准确地为现场清防蜡措施提供理论依据。     

Energy Saving in Industrial Wood Drying Addressed by a Multiscale Computational Model: Board, Stack, and Kiln

This article proposes a multiscale computational model able to calculate energy consumption in a batch lumber kiln. A dual-scale computational model of wood drying deals with the boards/stack interaction and serves as a basis for the present work. A new module was added here that calculates heat losses through kiln walls (convection, condensation) and the energy used by each kiln component (fans, heating elements, humidifier, vacuum pump, etc.). The corresponding mathematical formulation is presented and then theoretical results are compared to those collected in an industrial vacuum kiln. As application example, the effect of air reversal, air velocity, and kiln insulation are exhibited, which depicts the great potential and prospects of this new tool for energy savings in relation to the product quality.     

Modeling Temperature in Coupled Electrical and Thermal Simulations of the Electroconsolidation® Process

Electroconsolidation® is a process for densifying complex-shaped parts by using electrically conductive particulate solids as a pressure-transmitting medium. The part is immersed in a bed of the particulate medium contained in a die chamber. Sintering temperature is achieved by resistive heating of the medium while applying compaction pressure. The process is capable of ultrahigh temperatures and short cycle times and offers the potential for low processing costs.

Control of the process and selection of process conditions require knowledge of the temperatures within the die. Temperature gradients exist because of the high heating rate and because of variations of density and electrical resistivity of the medium due to the presence of the part. Direct measurement of temperature with thermocouples or other conventional means is impractical because of the high temperatures, high currents, and high pressures that are involved. Therefore, a computer model was developed to predict temperature as a function of time and applied voltage for any location in the die. The computer model is composed of three parts: a geometrical model to approximate the density and resistivity variations in the medium, a finite-element model to calculate the rate of resistive heating within each element, and a finite-difference model to calculate the temperature distribution based on solution of the heat-transfer equations. Predicted temperatures have been shown to be in excellent agreement with measurements, and numerical simulation provided encouraging consistency and reasonably accurate predictions of temperature profiles within the die. The model demonstrated the feasibility of a new process to achieve simultaneous application of pressure and heat to powder densification in Electroconsolidation.     

Controlling the losing probability in a monotone game

We deal with a complex game between Alice and Bob where each contender’s probability of victory grows monotonically by unknown amounts with the resources employed. For a fixed effort on Alice’s part, Bob increases his resources on the basis of the results for each round (victory, tie or defeat) with the aim of reducing the probability of defeat to below a given threshold. We read this goal in terms of computing a confidence interval for the probability of losing and realize that the moves in some contests may bring in an indeterminacy trap: in certain games Bob cannot simultaneously have both a low probability-of-defeat measure and a narrow confidence interval. We use the inferential mechanism called twisting argument to compute the above interval on the basis of two joint statistics. Careful use of such statistics allows us to avoid indeterminacy.     

Computational materials: Multi-scale modeling and simulation of nanostructured materials

The paper provides details on the current approach to multi-scale modeling and simulation of advanced materials for structural applications. Examples are given that illustrate the suggested approaches to predicting the behavior and influencing the design of nanostructured materials such as high-performance polymers, composites, and nanotube-reinforced polymers. Primary simulation and measurement methods applicable to multi-scale modeling are outlined. Key challenges including verification and validation are highlighted and discussed.     

亚齐示范屋与生态技术

亚齐示范屋是在传承印度尼西亚当地住宅传统的基础上，海啸灾区重建的示范性建筑。从当地传统的传承、设计理念及生态技术方面对该示范屋进行了分析、研究，结合我国的情况得出我国生态建筑的发展策略。     

Modeling of a multisector ecological economic system with lags

A model of a diversified ecological economic system with lags is proposed and investigated using sufficient optimality conditions. A turnpike solution of the problem, boundary trajectories, and control switchpoints are found. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 114–122, March–April 2007.