A note on the equivalence of the set covering and process network synthesis problems

In this paper, combining and completing some earlier results presented in this journal, it is proved that the Process Network Synthesis problem (PNS problem for short) is equivalent to the set covering problem

Bioenergy production and nutrients removal by green microalgae with cultivation from agro-wastewater palm oil mill effluent (POME) - A review

Environmental pollution specifically wastewater is gaining attention both in the developed and developing countries. Malaysia is considered as one of the major palm oil producers in the world. Therefore, it is important to develop an environmental friendly and economic method to treat palm oil mill effluent (POME). The wastewater can serve as an economical nutrient source or substrate that can support the cultivation of microalgae. This can be a great nutrient for algal cultivation at the same time as remediating effluent and generating biomass. Nowadays, many microalgae species are being investigated to determine their potential and effectiveness for phytoremediation application, especially high growth rate. However, using synthetic media for growing microalgae in a mass scale is costly. It is acknowledged that POME (as nutrients enriched media) assisted enhanced microalgae growth under certain condition can considerably reduce the presence of organic and inorganic compounds. In this review, the potential of wide range of the predominant microalgae species with main focus on green microalgae (high removal efficiency): Chlamydomonas sp and Chlorella sp were investigated. Moreover, we discussed about the history, methods and future prospects in nutrients removal by green microalgae comprehensively. This review discusses several potential strategies for tackling the environmental issue generated by agro-waste water POME with enhancement of biomass productivity which can be used as an alternative for energy production

Operációkutatási módszerek műszaki informatikai rendszerek analízisében és verifikációjában = Operation Research Methods for the Analysis and Verification of Information Technology Systems

Kidolgoztuk a Petri-hálók és produkciós hálók (PNS) egységes szemléletű leírását. Megfogalmaztuk az "optimális trajektória generálásának" problémáját Petri-hálós modellekre. A megoldásként kidolgozott és implementált algoritmus egyúttal temporális logikai követelményeket is vizsgál a modellen. Az algoritmust gyorsítottuk a PNS logikai bázisa fölötti kereséssel. A SPIN modellellenőrzőt magát használva egy másik megoldást is adtunk a problémára, valamint gráftranszformációs rendszerek optimalizálására. Megadtuk a lineáris korlátozási feltételekkel adott szeparábilis konkáv minimalizálási feladat egy elégséges optimalitási kritériumát, mely a Branch-and-Bound típusú algoritmusban használható fel megállási kritériumként. A magasszintű leírásokból a Petri-hálós modellbe történő transzformációkat matematikai alapokon definiáltuk, megvalósításukra automatikus modelltranszformációs megoldást dolgoztunk ki: egy algoritmust, amely GRM profillal adott modellből generálja a Petri-hálót, és egy általános algoritmust, amely UML modellekből származtat a diagnosztika alapjául szolgáló modelleket. Megvizsgáltuk ezen modellek illeszthetőségét a szabványokhoz. Multiprocesszoros rendszerek diagnosztizálására egy PNS technikákat használó algoritmust adtunk, melynek várható hatékonyságát igazoltuk. Munkálatok folytak a diagnosztika tesztalapú megközelítésére, és diagnosztikai modellek kísérletes paraméterezésére. Kísérleteket végeztünk az IBM Holosofx ipari workflow modellező eszköz illesztésére. | A unified treatment for Petri nets and process network (PNS) problems was defined. The 'optimal trajectory generation problem' for Petri nets was defined. Elaboration and implementation of an algorithm that is able not only to give the optimal trajectory but to verify temporal logic requirements for Petri nets. This algorithm was accelerated using Branch-and-Bound method over the logical basis of the feasible process networks. Another algorithm to solve the problem using only the SPIN model checker was elaborated. The optimization of graph transformation systems with time was solved based on the same technique. A sufficient optimality criteria was given for constrained, concave minimization problems. The precise mathematics of the model transformation from high-level models to Petri nets was defined, and automatic model transformations were carried out to realize these transformations: a transformation from UML models given by the GRM profile to Petri nets and a general algorithm that delivers models to diagnose from UML models. The conformancy of these models to standards was investigated. The probabilistic diagnosis problem in multiprocessor systems was solved using PNS techniques. The efficiency of the method was shown. There were efforts to elaborate a test-based approach of diagnostics, and to parameterize diagnostics models based on dependability experiments. Experiments were carried out to transform IBM Holosofx models to Petri nets

Vehicle Model-Based Driving Strategy Optimization for Lightweight Vehicle

In this paper, driving strategy optimization for a track is proposed for an energy efficient battery electric vehicle dedicated to the Shell Eco-marathon. A measurement-based mathematical vehicle model was developed to simulate the behavior of the vehicle. The model contains complicated elements such as the vehicle’s cornering resistance and the efficiency field of the entire powertrain. The validation of the model was presented by using the collected telemetry data from the 2019 Shell Eco-marathon competition in London (UK). The evaluation of applicable powertrains was carried out before the driving strategy optimization. The optimal acceleration curve for each investigated powertrain was defined. Using the proper powertrain is a crucial part of energy efficiency, as the drive has the most significant energy demand among all components. Two tracks with different characteristics were analyzed to show the efficiency of the proposed optimization method. The optimization results are compared to the reference method from the literature. The results of this study provide an applicable vehicle modelling methodology with efficient optimization framework, which demonstrates 5.5% improvement in energy consumption compared to the reference optimization theory

Vehicle Model-Based Driving Strategy Optimization for Lightweight Vehicle

In this paper, driving strategy optimization for a track is proposed for an energy efficient battery electric vehicle dedicated to the Shell Eco-marathon. A measurement-based mathematical vehicle model was developed to simulate the behavior of the vehicle. The model contains complicated elements such as the vehicle’s cornering resistance and the efficiency field of the entire powertrain. The validation of the model was presented by using the collected telemetry data from the 2019 Shell Eco-marathon competition in London (UK). The evaluation of applicable powertrains was carried out before the driving strategy optimization. The optimal acceleration curve for each investigated powertrain was defined. Using the proper powertrain is a crucial part of energy efficiency, as the drive has the most significant energy demand among all components. Two tracks with different characteristics were analyzed to show the efficiency of the proposed optimization method. The optimization results are compared to the reference method from the literature. The results of this study provide an applicable vehicle modelling methodology with efficient optimization framework, which demonstrates 5.5% improvement in energy consumption compared to the reference optimization theory

Retrofit Synthesis of Industrial Heat Exchanger Networks with Different Types of Heat Exchangers

Heat Exchanger Network (HEN) synthesis is a powerful tool for the development of more efficient processes with high utilization of mass and energy resources. The implementation of compact heat exchangers with enhanced heat transfer into the industrial flowsheets can provide more efficient and economically feasible solutions. Plate Heat Exchanger (PHE) is one of established types of enhanced HEs. To estimate possible benefits of that kind of heat transfer enhancement, a mathematical model of PHE, which accounts for different plate types and corresponding corrugations geometry, is used. The integration of this model with the P-graph-based HEN synthesis approach allowed to create the method, which considers different types of heat exchangers. This approach enables to integrate not only conventional shell-and-tube heat exchangers, but also PHEs, which overall heat transfer coefficient is in average 2-3 times higher, during the optimization process of a new or existing HEN. The capabilities of the proposed method are presented via a case study for oil preheat train, where an existing network is retrofitted; first with shell-and-tube heat exchangers only, then with the consideration of both shell-and-tube and plate heat exchangers