Recent developments in Process Integration

Process Integration supporting process design, integration and optimisation has been around for more than 40 years. Its development has been closely related to developing the Chemical Engineering, implementation of mathematical modelling and the application of information technology. Its development has been accelerating as the methodology has been able to provide answers and support for important issues regarding economic development—energy, water and resources better utilisation and savings. This contribution is targeted towards a short overview of recent achievements and future challenges.     

Outage analysis of selection diversity over Rayleigh fading channels with multiple co-channel interferers

In this paper an approach to the performance analysis of signal-to-interference (SIR) based selection combining (SC) operating over the Rayleigh fading channels experiencing an arbitrary number of multiple, Rayleigh co-channel interferers is presented. We have presented a general analysis of multibranch SC where each branch experiences an arbitrary number of multiple equal power co-channel interferers. Useful closed form expressions are derived for the probability density function (PDF) and cumulative distribution function (CDF) at the output of the combiner. Also an outage analysis is performed in order to show the effects of the number of multiple interferers, diversity order and input SIR unbalance to the system performances.     

Second‐Order Statistics of System with Microdiversity and Macrodiversity Reception in Gamma‐Shadowed Rician Fading Channels

In this letter, a wireless communication system with microdiversity and macrodiversity reception in gamma‐shadowed Rician fading channels is considered. Exact and rapidly converging infinite‐series expressions for the average level crossing rate and average fade duration at the output of the system are provided. Numerical results are presented graphically to illustrate the proposed mathematical analysis and to examine the effects of the system's parameters on the quantities considered.     

Maximum Likelihood Approach for RFID Tag Set Cardinality Estimation with Detection Errors

Estimation schemes of Radio Frequency IDentification (RFID) tag set cardinality are studied in this paper using Maximum Likelihood (ML) approach. We consider the estimation problem under the model of multiple independent reader sessions with detection errors due to unreliable radio communication links and/or collisions. In every reader session, both the detection error probability and the total number of tags are estimated. In particular, after the $R$ -th reader session, the number of tags detected in $j$ ( $j=1,2,...,R$ ) reader sessions out of $R$ sessions is updated, which we call observed evidence. Then, in order to maximize the likelihood function of the number of tags and the detection error probability given the observed evidences, we propose three different estimation methods depending on how to treat the discrete nature of the tag set cardinality. The performance of the proposed methods is evaluated under different system parameters and compared with that of the conventional method via computer simulations assuming flat Rayleigh fading environments and framed-slotted ALOHA based protocol.     

Antifungal efficiency of corona pretreated polyester and polyamide fabrics loaded with Ag nanoparticles

This study discusses the possibility of using the corona (electric discharge at atmospheric pressure) treatment for fiber surface activation that can facilitate the loading of Ag nanoparticles (NPs) from colloids onto the polyester and polyamide fabrics and thus enhance their antifungal activity against Candida albicans. The laundering durability of achieved effects and the influence of dyeing of fabrics with disperse dyes on their antifungal efficiency were studied. The morphology of fibers loaded with Ag nanoparticles was characterized by SEM whereas X-ray photoelectron spectroscopy was used for the evaluation of surface chemical changes. Corona pretreated polyester and polyamide fabrics loaded with Ag nanoparticles showed better antifungal properties compared to untreated fabrics. The advantage of corona treated fabrics became even more prominent after washing test, particularly for polyester fabrics. Antifungal efficiency of polyester and polyamide fabrics loaded with Ag nanoparticles were almost unaffected by dyeing process.     

Laboratory assessment of insecticidal effectiveness of natural zeolite and diatomaceous earth formulations against three stored-product beetle pests

The insecticidal effectiveness of two natural zeolite formulations (Minazel plus and Minazel), applied to wheat at selected rates of 0.25, 0.50 and 0.75 g/kg, and a diatomaceous earth formulation (DE) (Protect-It™), applied at the recommended rates of 0.15 g/kg for Sitophilus oryzae, 0.20 g/kg for Rhyzopertha dominica and 0.30 g/kg for Tribolium castaneum, were tested under laboratory conditions (24 ± 1 °C temperature and 45 ± 5% relative humidity). The highest adult mortality was observed after the longest exposure period of 21 days and 7 days of recovery, when all three zeolite dosage rates and the recommended DE dosage caused 97-100% mortality of S. oryzae and 94-100% of T. castaneum. On the other hand, 100% mortality was not achieved in any test variant involving R. dominica; the highest (about 92%) was detected for DE, while 52% and 79% mortality was achieved with the zeolites at the highest rate of 0.75 g/kg. Progeny reduction by >90% was achieved after 21 days of contact of all three beetle pests with DE-treated wheat, while the same level of reduction was achieved for S. oryzae and T. castaenum only after contact with the highest rate of the zeolite product, Minazel. Thus the two zeolite formulations are comparable to diatomaceous earth in controlling adult S. oryzae, R. dominica and T. castaneum, but only the Minazel formulation could effectively protect wheat from attack by S. oryzae or T. castaneum, and only with a higher rate of application than for the DE formulation.     

Optimal closed-loop control of a hybrid step motor with chopper drive

Optimal closed-loop control of a hybrid step motor control with chopper drive is described. Expressions for the average torque and optimal control angle giving maximal average torque in the stationary state without phase current chopper control are presented. The effects of chopper current control on the torque and acceleration characteristics of a hybrid step motor are discussed. Expression have been developed for the control angle in the chopper current control mode, yielding greater torques and improved acceleration of hybrid step motors than for the optimal control angle without phase current control. The speed response of a hybrid step motor operated in a closed-loop system has been studied by computer simulation for different supply voltages and torque loads, using various control angle algorithms.     

Development of residual strength evaluation tool based on stress-strain approximation

To allow for a safe design of metallic structures, it must be considered that, as a result of the manufacturing and processing operations, cracks or flaws below the NDI (Non-Destructive Inspection) detectability level always exist in the component after inspection. Further problems originate from the defect geometry. Failure of engineering structural components and structures have been mostly traced to surface cracks. Especially for a surface crack containing structure that is thin, the limit collapse of a ligament is usually the main cause of structure rupture. Study of the evaluation procedure relating to the limit load of the surface crack ligament is, therefore, an important project for conventional fracture assessment, particularly for pressure vessel (LBB) assessment. For this purpose, novel more accurate residual strength prediction method based on the Elasto-Plastic Fracture Mechanics (EPFM) has been developed and tested. Laboratory tests on tensile plate specimens with surface cracks were performed considering two different materials. In the final part of the work, effort was directed toward the verification and justification of selected analytical methods by adequate component testing. The most significant results of this work deal with residual strength evaluation for the thin wall pressure containing components. The important finding is that there is a potential for improvement in comparison to the current methods that may be used to increase payoff of the lightweight structures. The presented very robust analysis method and the useful structure integrity evaluation procedure should significantly contribute to the state-of-the-art structure optimisation and being applied to the design of the light-weight structures should ease the effort of the structure engineer to develop the successful and reliable hardware and to keep in place with advancing technologies. This revised version was published online in August 2006 with corrections to the Cover Date.     

Selective and synergistic activity of L-S,R-buthionine sulfoximine on malignant melanoma is accompanied by decreased expression of glutathione-S-transferase

L-buthionine-S,R-sulfoximine (BSO) selectivley inhibits glutathione (GSH) synthesis. Malignant melanoma may be uniquely dependent on GSH and its linked enzymes, glutathione S-transferase (GST) and GSH-peroxidase, for metabolism of reactive orthoquinones and peroxides produced during melanin synthesis. We compared the in vitro effects of BSO on melanoma cell lines and fresh melanoma specimens (n = 118) with breast and ovarian cell lines and solid tumors (n = 244). IC50 values (microM) for BSO on melanoma, breast and ovarian tumor specimens were 1.9, 8.6, and 29, respectively. The IC90 for melanoma was 25.5 microM, a level 20-fold lower than steady state levels achieved clinically. The sensitivity of individual specimens of melanoma correlated with their melanin content (r = 0.63). BSO synergistically enhanced BCNU activity against melanoma cell lines and human tumors. We followed GSH levels, GST enzyme activity, GST isoenzyme profiles and mRNA levels after BSO. BSO (50 microM) treatment for 48 hr resulted in a 95% decrease in ZAZ and M14 melanoma cell line GSH levels, and a 60% decrease in GST enzyme activity. GST-mu protein and mRNA levels were significantly reduced in both cell lines. GST-pi expression was unaffected. These data suggest that BSO action on melanoma may be related to GSH depletion, diminishing the capacity to scavenge toxic metabolites produced during melanin synthesis. We report here for the first time that BSO enhancement of alkylator action may be related in part to down regulation of GST. BSO may be a clinically useful adjunct in the treatment of malignant melanoma.     

Automated retrofit targeting of heat exchanger networks

The aim of this paper is to develop a novel heat exchanger network (HEN) retrofit method based on a new automated retrofit targeting (ART) algorithm. ART uses the heat surplus-deficit table (HSDT) in combination with the Bridge Retrofit concepts to generate retrofit bridges option, from which a retrofit design may be formulated. The HSDT is a tabular tool that shows potential for improved re-integration of heat source and sink streams within a HEN. Using the HSDT, retrofit bridges—a set of modifications that links a cooler to a heater to save energy—may be identified, quantified, and compared. The novel retrofit method including the ART algorithm has been successfully implemented in Microsoft ExcelTM to enable analysis of large-scale HENs. A refinery case study with 27 streams and 46 existing heat exchangers demonstrated the retrofit method’s potential. For the case study, the ART algorithm found 68903 feasible unique retrofit opportunities with a minimum 400 kW·unit^–1 threshold for heat recovery divided by the number of new units. The most promising retrofit project required 3 new heat exchanger units to achieve a heat savings of 4.24 MW with a favorable annualised profit and a reasonable payback period.

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