A new recycling system for expanded polystyrene using a natural solvent. Part 1. A new recycling technique

A new recycling technique has been developed which uses a natural solvent, d limonene, to shrink expanded polystyrene (EPS). d-Limonene is a natural vegetable oil which is extracted from the rinds of citrus fruits and is a good solvent of EPS. Limonene has almost the same solubility as toluene at room temperature. This technique reduces the volume of EPS to about 1/20th of the original. Contracted EPS is recyclable with almost no molecular weight degradation because d-limonene acts as an antioxidant of polystyrene during the heating process. © 1998 John Wiley & Sons, Ltd.     

A new recycling system for expanded polystyrene using a natural solvent. Part 2. Development of a prototype production system

A prototype production system for recycling expanded polystyrene (EPS), which uses an orange oil, d-limonene, as the EPS shrinking agent, has been developed. This system consists of an apparatus to dissolve EPS and a recycling plant to separate the limonene solution. The recycling plant can mass reproduce polystyrene with the same mechanical properties as new polystyrene. The recycled polystyrene can be used for packaging a 28 inch TV set. © 1998 John Wiley & Sons, Ltd.     

A new recycling method for expanded polystyrene

A new recycling method was investigated in this work, in which polystyrene (PS) sub‐µm fibres were electrospun from recycled expanded polystyrene (EPS). The experimental results in this work show that fibres with diameters of around 500 nm were produced by the electrospinning method. The fibres were produced to form a non‐woven mat. Non‐woven mats of electrospun fibres have large surface areas and small pore sizes compared to commercial textiles, making them excellent materials for use in filtration applications. Copyright © 2005 John Wiley & Sons, Ltd.     

Calculation of natural and forced vibrations of a piping system. Part 1. Analysis of vibrations of a 3D beam system

Dynamic behavior of piping as a beam system has been analyzed with the use of the dynamic stiffness method. According to this method, the equations describing the relation between unknown parameters are written by the method of initial parameters, therefore, the solution procedure is similar to that for a static problem. It is shown that for curvilinear beams it is simpler and more efficient to apply a model that consists of straight segments and inertia-free rotation elements. To determine natural frequencies of 3D beam systems, it is proposed to use a method of disconnection of displacements, which makes it possible to discern the frequencies corresponding to different vibration modes (transverse, longitudinal, etc.). The approach allows a correct simulation of the system behavior under forced vibrations induced by a harmonic exciting force. __________ Translated from Problemy Prochnosti, No. 1, pp. 79–93, January–February, 2007.     

Forward and backward risk assessment throughout a system life cycle using dynamic Bayesian networks: A case in a petroleum refinery

In this paper, risk modeling was conducted based on the defined risk elements of a conceptual risk framework. This model allows for the estimation of a variety of risks, including human error probability, operational risk, financial risk, technological risk, commercial risk, health risk, and social and environmental risks. Bayesian network (BN) structure learning techniques were used to determine the relationships among the model variables. By solving a bi-objective optimization problem applying the genetic algorithm (GA) with the Pareto ranking approach, the network structure was learned. Then, risk modeling was performed for a petroleum refinery focusing on HydroDeSulfurization (HDS) technology throughout its life cycle. To extend the model horizontally and make it possible to evaluate the risk trend throughout the technology life cycle, we developed a dynamic Bayesian network (DBN) with three-time slices. A two-way forward and backward approach was used to analyze the model. The model validation was performed by applying the leave-one-out cross-validation method.     

A new directional simulation method for system reliability. Part II: application of neural networks

A challenge in directional importance sampling is in identifying the location and the shape of the importance sampling density function when a realistic limit state for a structural system is considered in a finite element-supported reliability analysis. Deterministic point refinement schemes, previously studied in place of directional importance sampling, can be improved by prior knowledge of the limit state. This paper introduces two types of neural networks that identify the location and shape of the limit state quickly and thus facilitate directional simulation-based reliability assessment using the deterministic Fekete point sets introduced in the companion paper. A set of limit states composed of linear functions are used to test the efficiency and possible directional preference of the networks. These networks are shown in the tests and examples to reduce the simulation effort in finite element-based reliability assessment.     

A new directional simulation method for system reliability. Part I: application of deterministic point sets

To assess structural system reliability accurately, simulation is often the only feasible method because of dimensionality, highly nonlinear limit states, small failure probability and other factors. However, simulations can be computationally inefficient when the reliability assessment involves finite element analysis and the cost of structural analysis is large. Efficient directional simulation, as well as other simulation techniques, often can be improved in terms of accuracy and efficiency if the sample points are identified by deterministic point sets rather than generated randomly. This article introduces and investigates various deterministic point sets theoretically and experimentally in conjunction with directional simulation, and identifies one particular point set (Fekete point set) as being especially useful in this regard. New test measures are proposed to evaluate the quality and uniformity of point sets, which are essential in preserving the underlying probability distribution. A companion paper presents a point set refinement scheme using neural networks, which is a technique parallel to importance sampling.     

High performance nano-titania photocatalytic paper composite. Part I: Experimental design study for TiO2 composite sheet using a natural zeolite microparticle system and its photocatalytic property

Nanosized titanium dioxide (TiO₂) photocatalytic papers were successfully prepared using a natural zeolite microparticle retention aid in papermaking. Applying a factorial experimental design, natural zeolite has been demonstrated to be the most significant and interactive factor for increasing the TiO₂ retention rate in paper stock. The photocatalysis of as-prepared sheets was evaluated with toluene as one of the representative volatile organic compounds (VOCs). Under UV irradiation, it was shown to be effective in removing gaseous toluene by photodecomposition, assisted by adsorption. It was revealed that natural zeolite plays an important role in both increasing retention rate of TiO₂ nanoparticles and enhancing photocatalytic efficiency of the paper. The photocatalytic paper can be potentially applied for environmental purification.     

Effects of synthetic oil in a compression refrigeration system using R410A. Part II: quality of heat transfer and pressure losses within the heat exchangers

The consequences of the oil rejected by the compressor of a vapour-compression refrigeration system on the operation of the evaporator and condenser are analysed. The modelled prototype uses the mixture of HFC R410A and a synthetic polyolester (POE) oil. The rise of the amount of lubricant circulating in the system leads to a progressive change in the behaviour of the mixture of refrigerant and oil that, for the higher oil mass fraction, evolves like a zeotropic mixture. One also observes that the presence of lubricant is generally associated with a fall of the performances of the heat exchangers, except however in the evaporator where an optimum is observed when the quantity of oil is equal to 0.1% of the total mass of the mixture. Some conclusions are drawn about the choice of correlations for the calculation of the refrigerant side heat transfer coefficient in a plate evaporator.     

Prediction of area under the curve for a p-glycoprotein,a CYP3A4 and a CYP2C9 substrate using a single time point strategy: assessment using fexofenadine,itraconazole and losartan and metabolites

Abstract

Background: In the present age of polypharmacy, limited sampling strategy becomes important to verify if drug levels are within the prescribed threshold limits from efficacy and safety considerations. The need to establish reliable single time concentration dependent models to predict exposure becomes important from cost and time perspectives.

Methods: A simple unweighted linear regression model was developed to describe the relationship between C_max versus AUC for fexofenadine, losartan, EXP3174, itraconazole and hydroxyitraconazole. The fold difference, defined as the quotient of the observed and predicted AUC values, were evaluated along with statistical comparison of the predicted versus observed values.

Results: The correlation between C_max versus AUC was well established for all the five drugs with a correlation coefficient (r) ranging from 0.9130 to 0.9997. Majority of the predicted values for all the five drugs (77%) were contained within a narrow boundary of 0.75- to 1.5-fold difference. The r values for observed versus predicted AUC were 0.9653 (n?=?145), 0.8342 (n?=?76), 0.9524 (n?=?88), 0.9339 (n?=?89) and 0.9452 (n?=?66) for fexofenadine, losartan, EXP3174, itraconazole and hydroxyitraconazole, respectively.

Conclusions: C_max versus AUC relationships were established for all drugs and were amenable for limited sampling strategy for AUC prediction. However, fexofenadine, EXP3174 and hydroxyitraconazole may be most relevant for AUC prediction by a single time concentration as judged by the various criteria applied in this study.     

Effects of synthetic oil in a compression refrigeration system using R410A. Part I: modelling of the whole system and analysis of its response to an increase in the amount of circulating oil

Results concerning a model of vapour compression refrigeration system using R410A, a binary HFC blend, and designed to take into account the effects of the oil rejected by the compressor, are presented. These effects are negligible when the lubricant does not exceed 0.5% of the total refrigerant weight; above this value, the performances of the system decrease significantly.