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Authors - 9829
Seyed Ali Emamian
57204544563
Aminoddin Haji
37080812200
Armanay Savanchiyeva
57194566646
Rashad Alsirawan
57951728200
Publications - 6383
Modeling of Organic Fouling in an Ultrafiltration Cell Using Different Three-Dimensional Printed Turbulence Promoters
Publication Name: Membranes
Publication Date: 2023-03-01
Volume: 13
Issue: 3
Page Range: Unknown
Description:
Designing turbulence promoters with optimal geometry and using them for ultrafiltration systems has been a key challenge in mitigating membrane fouling. In this study, six different turbulence promoters were created using three-dimensional printing technology and applied in dead-end ultrafiltration. Three-dimensional-printed (3DP) turbulence promoter configurations were integrated into a classical batch ultrafiltration cell. The effects of these configurations and the stirring speeds on the permeate filtration flux, organic rejections, and membrane resistances were investigated. The fouling control efficiency of the 3DP promoters was evaluated using two polyethersulfone membranes in a stirred ultrafiltration cell with model dairy wastewater. The Hermia and resistance-in-series models were studied to further investigate the membrane fouling mechanism. Of the Hermia models, the cake layer model best described the fouling in this membrane filtration system. It can be concluded that the 3DP turbulence promoters, combined with intense mechanical stirring, show great promise in terms of permeate flux enhancement and membrane fouling mitigation. Using a well-designed 3DP turbulence promoter improves the hydrodynamic flow conditions on the surface of the stirred membrane separation cells based on computational fluid dynamics modeling. Therefore, the factors effecting the fabrication of 3DP turbulence promoters are important, and further research should be devoted to revealing them.
Open Access: Yes
Multi-threaded Bacterial Iterated Greedy heuristics for the Permutation Flow Shop Problem
Publication Name: Cinti 2012 13th IEEE International Symposium on Computational Intelligence and Informatics Proceedings
Publication Date: 2012-12-01
Volume: Unknown
Issue: Unknown
Page Range: 63-66
Description:
This paper proposes approaches for combining Iterated Greedy techniques, as state-of-the-art methods, with bacterial evolutionary algorithms based on a hybrid technique involving the Multi-Threaded Iterated Greedy heuristic and a memetic algorithm in order to efficiently solve the Permutation Flow Shop Problem on parallel computing architectures. In the present work three novel approaches are proposed by combining a variant of the Bacterial Memetic Algorithm and the recently proposed Bacterial Iterated Greedy technique with the mentioned hybrid multi-threaded approach. The techniques thus obtained are evaluated via simulation runs carried out on a series of data from the well-known Taillard's benchmark problem set. Based on the experimental results the multi-threaded hybrid methods are compared to each other and to the original techniques (i.e. to the techniques without bacterial algorithms). © 2012 IEEE.
Open Access: Yes
Adaptive differential evolution approaches in real-time optimization of co-generation systems for enhanced energy minimization
Publication Name: Thermal Science and Engineering Progress
Publication Date: 2026-03-01
Volume: 71
Issue: Unknown
Page Range: Unknown
Description:
This paper examines Real Time Optimization (RTO) for an industrial cogeneration plant featuring a tightly coupled multi boiler turbine network, in which fluctuating steam and power demands and fuel price volatility necessitate continual economic re optimization while preserving closed loop stability. Three evolutionary optimizers are Differential Evolution (DE), Hybrid Differential Evolution (HDE), and Adaptive Differential Evolution (ADE) deployed as the supervisory RTO layer above the regulatory controllers, with Model Predictive Control (MPC) regulating boiler pressure (Control Variable 1, CV1) and drum level CV2 and PI or PI loops regulating turbine power. A deterministic, repeatable stress test is introduced through sequential step changes in high pressure steam demand, medium pressure steam demand, power demand, and natural gas price, enabling systematic evaluation of transient adaptability and robustness. Over five boilers and the turbine network, multi run mean and deviation results show that ADE delivers the most consistent overall behavior, yielding smoother operating trajectories, improved tracking, and lower energy usage. Specifically, the total integrated energy consumption is approximately 895 MWh with ADE, compared to 926 MWh with DE and 1259 MWh with HDE, equivalent to reductions of about 3 percent versus DE and 29 percent versus HDE. Control performance improves in parallel the mean boiler pressure (Integral Square Error) ISE CV1 drops by roughly 68 percent relative to DE and 71 percent relative to HDE, while turbine regulation shows substantial enhancement with turbine ISE reduced by about 98 percent compared with DE. Overall, the results demonstrate that adaptive evolutionary optimization strengthens coordination between the RTO and control layers, providing a robust and energy efficient strategy for real time cogeneration operation under dynamic demand and price disturbances.
Open Access: Yes
Examining Shape Dependence on Small Mild Steel Specimens during Heating Processes
Publication Name: Materials
Publication Date: 2024-08-01
Volume: 17
Issue: 16
Page Range: Unknown
Description:
With regard to the heating technology of small test specimens (D < 1 inch, i.e., 25.4 mm), only a limited amount of data and literature are available for making adequate technological decisions. Heating time of small geometric shapes is influenced by the technological parameters of the furnace, the temperature, the disposition technique in the furnace and the geometric characteristics of the workpiece. How to shorten heating time to achieve a suitable material structure is a vital question, while considerable energy is saved at the same time. Among the geometric characteristics, shape dependence is one of the important aspects that must be taken into account in terms of heating technology. Shape dependence is usually taken into account with empirically produced correction factors, which can result in significant oversizing of heating time, energy-wasting technology and material structure of insufficient fineness. In the course of our work, we investigated and compared the shape dependence of cylindrical and prismatic specimens with the same surface-to-volume ratios, which were combined with surface heat transfer analyses and geometric effect tests to formulate new approximate equations for determining heating time. As a result, we could mathematically derive a relationship between heating time, size and shape of the active surfaces, the correlation of which can shorten heating time by 20%. In addition, a shape factor (1.125) between cylinder and prismatic-shaped specimens was determined, which can be used with the new equation to calculate heating time for similar specimens. At last, a relationship is developed between the amount of heat that can be stored in the body during heat equalization and the complexity of the shape, which can be characterized through ratios depending on heating times and active surfaces in the function of total surface/volume ratio. Based on this relationship it can be determined more precisely when heat equalization occurs; therefore, shorter heating time can be achieved. In conclusion, with the help of this new method, optimal heating time for structural steel components, in the case of small cross-section and weight, can be determined.
Open Access: Yes
DOI: 10.3390/ma17163912
Optimization-based parameter tuning of unscented Kalman filter for speed sensorless state estimation of induction machines
Publication Name: Proceedings 2017 5th International Symposium on Electrical and Electronics Engineering Iseee 2017
Publication Date: 2017-12-07
Volume: 2017-December
Issue: Unknown
Page Range: 1-7
Description:
State estimation of induction machines may be a difficult problem, due to the non-linear behavior of theirs. For non-linear state estimation, the unscented Kalman filter (UKF) is a well-known extension of the linear Kalman filter. Operation of the UKF algorithm strongly depends on the process and measurement noise covariance parameters of the estimator. Determination of these parameters is not straightforward and can be difficult, especially if the number of state variables and hence the system complexity is relatively high. In this paper, the UKF algorithm is applied for speed sensorless state estimation of induction machines in such a way that seven state variables are estimated from the measured stator currents and from the known excitation voltages. In order to tune the noise parameters of the UKF, a new, optimization-based method is presented. This tuning method provides adequate behavior for the observer beside difficult operating conditions as it has been shown by simulation experiment.
Open Access: Yes
Dynamics of Fuzzy Cognitive Maps with Uncertain Weights
Publication Name: Studies in Fuzziness and Soft Computing
Publication Date: 2024-01-01
Volume: 427
Issue: Unknown
Page Range: 121-133
Description:
In real-life problems, the weights of the connections between the concepts are often not known exactly. This uncertainty can be modelled in different ways, based on different considerations. In this chapter, we discuss two models, regarding the nature of uncertainty. Fuzzy grey cognitive maps (FGCMs) employ grey system theory to represent vagueness of the causal connections. This approach assumes that we do know the range of the unknown weight, but within this range we do not have any further information. In other words, the model assumes known extension, but unknown intension. In classical fuzzy cognitive maps the weights are single numbers, so the fuzziness is not present there. Fuzzy set valued fuzzy cognitve maps handle this known issue by assigning fuzzy sets to the connections, so in this model the intension of a weight is known, but the extension is not exactly clear. These models behave somewhat similarly to classical fuzzy cognitive maps. The final conclusion about the modelled system is based on the limiting behaviour of the iteration process. This iteration may converge to an equilibrium point, may arrive to limit cycles or may produce unstable behaviour. In this chapter, sufficient conditions for the existence and uniqueness of fixed points of fuzzy grey and fuzzy set valued FCMs are provided.
Open Access: Yes
The genetic status of the Hungarian brown trout populations: Exploration of a blind spot on the European map of Salmo trutta studies
Publication Name: Peerj
Publication Date: 2018-01-01
Volume: 2018
Issue: 9
Page Range: Unknown
Description:
Background. Analyses of the control region sequences of European brown trout populations’ mitrochondrial DNA have revealed five main evolutionary lineages (Atlantic, Danubian, Mediterranean, Adriatic, Marble) mostly relating to the main water basins; however, the hybridization between lineages were increasingly reported. Due to the hydrogeography of Hungary, wild populations should theoretically belong to the Danubian lineage, however, this has not been verified by genetic studies. Methods. In our study multiple molecular marker sets (mitochondrial sequence, microsatellites, PCR-RFLP of nuclear markers and sex marker) were used to investigate the genetic composition and population genetics of the brown trout populations in two broodstocks, six wild streams in Hungary and one Serbian population. Results. The admixture of Atlantic and Danubian lineages in these populations, except the Serbian population with pure Danubian origin, was observed by control region sequences of mitochondrial DNA and PCR-RFLP markers in the nuclear genome, and one unpublished Danubian haplotype was found in Hungarian populations. A sex-specific marker revealed equal gender ratio in broodstocks and Kemence stream, whereas in other wild streams the proportion of female individuals were less than 50%. Structure and principal component analyses based on the alleles of microsatellite loci also revealed overlapping populations, however the populations were still significantly different from each other and were mostly in Hardy-Weinberg equilibrium. Discussion. Stocking and migration can have a significant genetic impact on trout populations of wild streams, however there are no guidelines or common practices for stocking of small streams in Hungary, thus the genetic background of these populations should be considered when developing conservation actions.
Open Access: Yes
DOI: 10.7717/peerj.5152
Investigation of the Causes of Railway Track Gauge Narrowing
Publication Name: Vehicles
Publication Date: 2023-09-01
Volume: 5
Issue: 3
Page Range: 949-977
Description:
On behalf of MÁV Hungarian State Railways Ltd., the authors carried out a research and development (R&D) project on behalf of the Budapest University of Technology and Economics, Department of Highway and Railway Engineering, on the subject of “Research and investigation of the causes of gauge narrowing by finite-element modeling in running track and turnout, and under operational and laboratory conditions”. The main objective of the research was to investigate the causes of localized defects of gauge narrowing in railway tracks based on machine and manual track measurements, laboratory measurements, and theoretical considerations. The measures proposed as a consequence of identifying the causes could significantly contribute to reducing the number and extent of local defects in the future. Furthermore, the research aims to develop new theories in less scientifically mature areas and provide procedures and instructions that professional engineers and practitioners can easily apply. The main areas of research, which are not exhaustive, are as follows: (i) the evaluation of the measurement results provided by track geometry measuring and recording cars; (ii) on-site investigations in the railway track in terms of gauge and rail profile measurements; and, based on these, (iii) the selection of concrete sleepers, which were removed from the track and subjected to more detailed geometrical investigations in the laboratory, together with the components of the rail reinforcement; (iv) the track–vehicle connection, tight running in straight and curved track sections under track confinement; (v) modeling of the stability and deflection of the rail when the rail fastenings lose part of their supporting function; and (vi) finite element modeling of the concrete sleepers under operating conditions such as slow deformation of the concrete, temperature variation effects, and lateral support on the ballast. In the already-narrowed track section, the tight vehicle running is not the cause of the track gauge narrowing but a consequence, so it is not investigated in this paper.
Open Access: Yes
3D DEM Analysis of Particle Breakage Effect on Direct Shear Tests of Coarse Sand
Publication Name: Materials
Publication Date: 2023-07-01
Volume: 16
Issue: 14
Page Range: Unknown
Description:
This paper explores the effect of particle breakage on the mechanical behavior of coarse sand through 3D Discrete Element Method (DEM) simulations of direct shear tests (DST). The objective is to gain insights into the macro- and micro-mechanical behaviors of crushable coarse sand, with a particular focus on the stress–strain relationship, volumetric deformation, and evolution of grain crushing. The simulations involve a comparison between non-crushable and crushable particle models, where the crushable particles are implemented in the shear zone of the DST subjected to different high normal stresses. The findings indicate that the crushable particles experience partial crushing at peak shear stress, with further particle crushing leading to the production of finer particles at the shearing plane during shearing at the critical state. The migration of these finer particles under pressure and gravity generates their accumulation predominantly in the lower section of the simulation box. Importantly, the presence of crushing in the DST induces a decrease in the shear stress and an increase in the volumetric strain leading to contractive behavior instead of dilation, which gradually stabilizes the volumetric deformation at higher normal stresses.
Open Access: Yes
DOI: 10.3390/ma16145025
