Статті в журналах: "Refrigeration industry Mathematical models"

1

Tai, Yanni, Haibin Qu, and Xingchu Gong. "Design Space Calculation and Continuous Improvement Considering a Noise Parameter: A Case Study of Ethanol Precipitation Process Optimization for Carthami Flos Extract." Separations 8, no. 6 (May 24, 2021): 74. http://dx.doi.org/10.3390/separations8060074.

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The optimization of process parameters in the pharmaceutical industry is often carried out according to the Quality by Design (QbD) concept. QbD also emphasizes that continuous improvement should be performed in life cycle management. Process parameters that are difficult to control in actual production can be regarded as noise parameters. In this study, based on the QbD concept, the ethanol precipitation process of Carthami Flos extract was optimized, considering a noise parameter. The density of the concentrated extract, ethanol concentration, the volume ratio of ethanol to concentrated extract, stirring time after ethanol addition, and refrigeration temperature were selected as critical process parameters (CPPs), using a definitive screening design. The mathematical models among CPPs and evaluation indicators were established. Considering that the refrigeration temperature of industrial ethanol precipitation is often difficult to control with seasonal changes, refrigeration temperature was treated as a noise parameter. A calculation method for the design space in the presence of the noise parameter was proposed. The design space was calculated according to the probability of reaching the standards of evaluation indicators. Controlling parameters within the design space was expected to reduce the influence of noise parameter fluctuations on the quality of the ethanol precipitation supernatant. With more data obtained, the design space was updated. In industry, it is also recommended to adopt a similar idea: that is, continuing to collect industrial data and regularly updating mathematical models, which can further update the design space and make it more stable and reliable.

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Gabibov, Ibrahim Abulfaz, Rabiya Seydulla Nadjafkulieva, and Sevinj Malik Abasova. "MODELING THE HEAT TRANSFER PROCESS IN REFRIGERATION UNITS USED IN THE OIL INDUSTRY." EUREKA: Physics and Engineering 6 (November 30, 2019): 57–62. http://dx.doi.org/10.21303/2461-4262.2019.001056.

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Currently, the main volume of associated petroleum gas production in Azerbaijan is carried out at offshore fields. About 30 % of this volume is used for SOCAR’s own technological needs of the oil company (to maintain the level of oil production). And the rest are transported to onshore facilities and further for processing to a gas processing plant. Subsequently, dry and purified gas is sent through a gas pipeline system for use by the population, or to a network of trunk pipelines for further export. When gas is transferred to the gas lift system and ashore, it is compressed in compressors, as a result of which the temperature of the working agent rises. The latter dramatically reduces the level of operational safety of the entire process. Based on the foregoing, ensuring the required gas quality at the outlet of the compressor unit is an important and urgent task. Currently used in the gas cooling system, shell-and-tube type refrigeration units have several advantages: high heat transfer coefficient, operability in low and high pressure modes, simplicity of design and service. Along with this, these units are distinguished by large dimensions and high metal consumption, noise effect, vibration, etc. A new design of a heat exchanger for cooling associated petroleum gas at the outlet of gas motor compressors is proposed. Based on the modeling of the heat transfer process, mathematical models have been obtained that make it possible to adequately evaluate the cooling process in the proposed refrigeration device.

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Ke, Hanbing, Yuansheng Lin, Zhiwu Ke, Qi Xiao, Zhiguo Wei, Kai Chen, and Huijin Xu. "Analysis Exploring the Uniformity of Flow Distribution in Multi-Channels for the Application of Printed Circuit Heat Exchangers." Symmetry 12, no. 2 (February 22, 2020): 314. http://dx.doi.org/10.3390/sym12020314.

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The maldistribution of fluid flow through multi-channels is a critical issue encountered in many areas, such as multi-channel heat exchangers, electronic device cooling, refrigeration and cryogenic devices, air separation and the petrochemical industry. In this paper, the uniformity of flow distribution in a printed circuit heat exchanger (PCHE) is investigated. The flow distribution and resistance characteristics of a PCHE plate are studied with numerical models under different flow distribution cases. The results show that the sudden change in the angle of the fluid at the inlet of the channel can be greatly reduced by using a spreader plate with an equal inner and outer radius. The flow separation of the fluid at the inlet of the channel can also be weakened and the imbalance of flow distribution in the channel can be reduced. Therefore, the flow uniformity can be improved and the pressure loss between the inlet and outlet of PCHEs can be reduced. The flow maldistribution in each PCHE channel can be reduced to ± 0.2%, and the average flow maldistribution in all PCHE channels can be reduced to less than 5% when the number of manifolds reaches nine. The numerical simulation of fluid flow distribution can provide guidance for the subsequent research and the design and development of multi-channel heat exchangers. In summary, the symmetry of the fluid flow in multi-channels for PCHE was analyzed in this work. This work presents the frequently encountered problem of maldistribution of fluid flow in engineering, and the performance promotion leads to symmetrical aspects in both the structure and the physical process.

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4

Baglivo, Cristina, Paolo Maria Congedo, and Pasquale Antonio Donno. "Analysis of Thermodynamic Cycles of Heat Pumps and Magnetic Refrigerators Using Mathematical Models." Energies 14, no. 4 (February 9, 2021): 909. http://dx.doi.org/10.3390/en14040909.

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This paper proposes a critical review of the different aspects concerning magnetic refrigeration systems, and performs a detailed analysis of thermodynamic cycles, using mathematical models found in the literature. Langevin’s statistical mechanical theory faithfully describes the physical operation of a refrigeration machine working according to a magnetic Ericsson cycle. Results of mathematical and real experimental models are compared to deduce which best describes the Ericsson cycle. The theoretical data are not perfectly consistent with the experimental data; there is a maximum deviation of about 30%. Numerical and experimental data confirm that very high Coefficient of Performance (COP) values of more than 20 can be achieved. The analysis of the Brayton cycle consisted of finding the mathematical model that considers the irreversibility of these machines. Starting from the thermodynamic properties of magnetocaloric materials based on statistical mechanics, the efficiency of an irreversible Brayton regenerative magnetic refrigeration cycle is studied. Considering the irreversibility in adiabatic transformations, the lower limit of the optimal ratio of two magnetic fields is determined, obtaining a valid optimization criterion for these machines operating according to a Brayton cycle. The results show that the Ericsson cycle achieves a higher Coefficient of Performance than the Brayton cycle, which has a higher cooling capacity as it operates with a larger temperature difference between the magnetocaloric material and source.

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5

Mani, Kolandavel, Vellappan Selladurai, and Natarajan Murugan. "Experimental investigations with eco-friendly refrigerants using design of experiments technique-mathematical modeling and experimental validation." Thermal Science 18, suppl.2 (2014): 363–74. http://dx.doi.org/10.2298/tsci110805114m.

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In this paper mathematical models were developed using design of experiments technique for the performance prediction of refrigeration system parameters such as refrigerating capacity, power consumption and coefficient of performance. The models developed were checked for their adequacy using F-test. The performances of vapour compression refrigeration system with different refrigerants R12, R134a and R290/R600a were compared. The R290/R600a mixture showed 10.7-23.6% higher coefficient of performance than that with R12 and R134a and it was found that the hydrocarbon mixture with 68% propane and 32% iso-butane could be used as a substitute for R12 and R134a.

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Gonçalves, R. S. R., B. Jacob-Furlan, E. C. Kollross, J. C. Berndsen, L. S. Martins, A. B. Mariano, and J. C. Ordonez. "A MATHEMATICAL MODEL OF AN ABSORPTION REFRIGERATION SYSTEM FOR A REFRIGERATED STORAGE FOR FISHING BOATS." Revista de Engenharia Térmica 21, no. 1 (July 8, 2022): 25. http://dx.doi.org/10.5380/reterm.v21i1.86688.

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The objective of this paper is to determine if it is possible to refrigerate an area by means of a heat source. Theory determines that an absorption refrigerator can work as a possible solution through a refrigeration fluid. According to it, the system works by the evaporation or condensation of the working fluid. The traditional process consists of using engine fuel to run an electric compressor and by its means achieve refrigeration. That process has its toll on fuel economy and engine efficiency and the refrigeration fluid damages the ozone layer or is based on the transportation of ice previously bought on shore. The technological improvement will be equipped on fishing boats, in order to make the trip last longer due to the possibility of not needing to buy and transport ice and for the purpose of lowering the fishing industry cost. Absorption refrigeration can augment engine efficiency by using heat energy that is normally wasted and the system could reach temperatures of freezing water, meaning that it could be possible to follow Brazilian and international standards. The methodology of this work consists of an energy analysis of an absorption refrigerator, which is the determination of the heat transfer equations on the ammonia evaporator, condenser and exhaust/ammonia. Furthermore, it should be analyzed if it’s possible to determine to which working parameters the system will have an optimum operation. From the mathematical analysis, the system shows that with the equations it is possible to operate an absorption refrigeration based on the exhaust gases of fishing boats. Furthermore, the process can be operated on a wide range of temperatures, being possible to determine according to a few dimensionless parameters to which temperature levels the process of refrigeration shows the best removal of heat.

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7

Minaev, V. A., V. M. Pizengolts, A. O. Faddeev, A. Y. Bystryakov, E. V. Savenkova, and E. V. Kruglikova. "Modern information and mathematical models in construction industry." E3S Web of Conferences 116 (2019): 00051. http://dx.doi.org/10.1051/e3sconf/201911600051.

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Building information modelling (BIM) – new technology of construction object information maintenance. It allows specifying influence of changes and risks made in it (including geodynamic) at all stages of lifecycle. Objects include products, building equipment, technological platform, the building, engineering, transportation networks and systems of building communication. The model expands possibilities of innovative technologies implementation, allowing creating reasoned economic decisions.

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8

Liu, Shi Qiang, and Erhan Kozan. "Integration of mathematical models for ore mining industry." International Journal of Systems Science: Operations & Logistics 6, no. 1 (July 5, 2017): 55–68. http://dx.doi.org/10.1080/23302674.2017.1344330.

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9

Kumar, Naresh, and Balraj Singh. "Forecast of Indian Automobile Industry Using Mathematical Models." Paradigm 7, no. 2 (July 2003): 105–16. http://dx.doi.org/10.1177/0971890720030207.

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10

Izquierdo, J., R. Pérez, and P. L. Iglesias. "Mathematical models and methods in the water industry." Mathematical and Computer Modelling 39, no. 11-12 (June 2004): 1353–74. http://dx.doi.org/10.1016/j.mcm.2004.06.012.

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11

Wang, Lin, Xiao Long Cui, Ying Ying Tan, and Yu Wang. "Study on Energy Efficiency of a Low Temperature Refrigeration System." Applied Mechanics and Materials 71-78 (July 2011): 292–95. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.292.

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Based on conservation of mass, total mass balance equation and component mass balance equation, mathematical models of thermodynamic for the auto cascade refrigeration cycle are established. Thermophysical properties in solving the governing equation are called from the NIST REFPROP7.0. Thermodynamic properties of the auto cascade refrigeration cycle using binary mixtures, namely, R170/R290, R23/R227ea, R116/R134a, R23/R134a, R170/R600a, R170/R600 and R170/R152a as refrigerants is evaluated. R170/R600a is selected for the low temperature refrigeration system, and the influences of cycle mole fraction, compression ratio and evaporating pressure on the cycle performance are analysed.

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12

Pérez-Gomariz, Mario, Antonio López-Gómez, and Fernando Cerdán-Cartagena. "Artificial Neural Networks as Artificial Intelligence Technique for Energy Saving in Refrigeration Systems—A Review." Clean Technologies 5, no. 1 (January 11, 2023): 116–36. http://dx.doi.org/10.3390/cleantechnol5010007.

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The refrigeration industry is an energy-intensive sector. Increasing the efficiency of industrial refrigeration systems is crucial for reducing production costs and minimizing CO2 emissions. Optimization of refrigeration systems is often a complex and time-consuming problem. This is where technologies such as big data and artificial intelligence play an important role. Nowadays, smart sensorization and the development of IoT (Internet of Things) make the massive connection of all kinds of devices possible, thereby enabling a new way of data acquisition. In this scenario, refrigeration systems can be measured comprehensively by acquiring large volumes of data in real-time. Then, artificial neural network (ANN) models can use the data to drive autonomous decision-making to build more efficient refrigeration systems.

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13

Poletaykin, V. F., and G. N. Plesovskikh. "Mathematical models of timber loader motion." Traktory i sel hozmashiny 80, no. 11 (November 15, 2013): 24–26. http://dx.doi.org/10.17816/0321-4443-65728.

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14

James, K. A., and R. W. James. "Transient analysis of thermostatic expansion valves for refrigeration system evaporators using mathematical models." Transactions of the Institute of Measurement and Control 9, no. 4 (October 1987): 198–205. http://dx.doi.org/10.1177/014233128700900406.

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Syazin, Ivan Evgen'evich, Gennadiy Ivanovich Kas'yanov, and Aleksandr Valerievich Gukasyan. "Osobennosti teplovogo rascheta porshnevogo kholodil'nogo kompressora." Refrigeration Technology 109, no. 6 (June 15, 2020): 20–24. http://dx.doi.org/10.17816/rf104046.

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Designing refrigeration reciprocal compressors is a knotty engineering problem. Refrigeration reciprocal compressors differ considerably from the gas ones. To calculate refrigeration reciprocal compressors specially developed mathematical models, which are described in educational and scientific literature, are used. A number of hairy calculations should be performed when designing a compressor. One of them is a thermal calculation intended for determining the baselines of the designed compressor, which will be the basis for following calculations such as gasdynamic, dynamic, strength ones, etc. When performing the thermal calculation, the designer needs to find the optimal values of the diameter and stroke of the piston (basic design indicators), making a start from the calculated data and the indicator diagram. This article considers the main features of the thermal calculation of a refrigeration reciprocal compressor based on a specific example

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16

Yang, Shutong, Youlei Wang, and Yufei Wang. "Optimization of Cascade Cooling System Based on Lithium Bromide Refrigeration in the Polysilicon Industry." Processes 9, no. 9 (September 18, 2021): 1681. http://dx.doi.org/10.3390/pr9091681.

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Cascade cooling systems containing different cooling methods (e.g., air cooling, water cooling, refrigerating) are used to satisfy the cooling process of hot streams with large temperature spans. An effective cooling system can significantly save energy and costs. In a cascade cooling system, the heat load distribution between different cooling methods has great impacts on the capital cost and operation cost of the system, but the relative optimization method is not well established. In this work, a cascade cooling system containing waste heat recovery, air cooling, water cooling, absorption refrigeration, and compression refrigeration is proposed. The objective is to find the optimal heat load distribution between different cooling methods with the minimum total annual cost. Aspen Plus and MATLAB were combined to solve the established mathematical optimization model, and the genetic algorithm (GA) in MATLAB was adopted to solve the model. A case study in a polysilicon enterprise was used to illustrate the feasibility and economy of the cascade cooling system. Compared to the base case, which only includes air cooling, water cooling, and compression refrigeration, the cascade cooling system can reduce the total annual cost by USD 931,025·y−1 and save 7,800,820 kWh of electricity per year. It also can recover 3139 kW of low-grade waste heat, and generate and replace a cooling capacity of 2404 kW.

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17

Giovannini, Michael, and Marco Lorenzini. "Numerical Model of an Evaporative Condenser for the Food Refrigeration Industry." Journal of Physics: Conference Series 2177, no. 1 (April 1, 2022): 012009. http://dx.doi.org/10.1088/1742-6596/2177/1/012009.

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Abstract Evaporative condensers play a key role in refrigeration plants for industrial applications, as they are needed to dispose of the thermal and electric power required by the process. Modelling them as lumped capacitance systems is very expedient when trying to simulate e. g. the steady-state and dynamic behaviour of the whole refrigeration plant, but at the expenses of loss of information and often oversimplifying assumptions. This paper analyses two models for heat and mass transfer in cooling equipment, Poppe’s and its earlier, simpler version, Merkel’s. The two approaches are applied to describe the transport phenomena in an evaporative condenser and the predicted cooling power compared to the data declared by the manufacturer under certain operating conditions. It is demonstrated that predictions are accurate within less than 10%.

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Ge, Y. T., and S. A. Tassou. "Mathematical modelling of supermarket refrigeration systems for design, energy prediction and control." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 214, no. 2 (March 1, 2000): 101–14. http://dx.doi.org/10.1243/0957650001538218.

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This paper describes a mathematical model developed to simulate the performance of supermarket refrigeration systems. Such a model can be used for the comparison of different systems and control strategies in terms of their energy and total equivalent warming impact. The model is based on a large number of component models which have been linked together within the TRNSYS environment. Major component models include the compressor, air-cooled condenser, thermostatic expansion valve, display cabinet and control. The overall system model has been validated against monitored data obtained from both a laboratory-based system and a full-scale system in a supermarket in Scotland. The value of the model is illustrated by determining and comparing the effectiveness of head pressure and variable-speed control against fixed head pressure and constant speed control. It is shown that even at summer ambient conditions the system can be operated without problems at much lower head pressures than is done in practice under fixed-pressure control strategies. The use of variable-speed control on one of the compressors can also provide better control of the suction pressure and a substantial (up to 23 per cent) energy savings compared to on-off control.

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Estrada-Flores, S., D. J. Cleland, A. C. Cleland, and R. W. James. "Simulation of transient behaviour in refrigeration plant pressure vessels: mathematical models and experimental validation." International Journal of Refrigeration 26, no. 2 (March 2003): 170–79. http://dx.doi.org/10.1016/s0140-7007(02)00081-6.

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Zhuk, Tetyana. "Mathematical Models of Reinsurance." Mohyla Mathematical Journal 3 (January 29, 2021): 31–37. http://dx.doi.org/10.18523/2617-70803202031-37.

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Insurance provides financial security and protection of the independence of the insured person. Its principles are quite simple: insurance protects investments, life and property. You regularly pay a certain amount of money in exchange for a guarantee that in case of unforeseen circumstances (accident, illness, death, property damage) the insurance company will protect you in the form of financial compensation.Reinsurance, in turn, has a significant impact on ensuring the financial stability of the insurer. Because for each type of insurance there is a possibility of large and very large risks that one insurance company can not fully assume. In the case of a portfolio with very high risks, the company may limit their acceptance, or give part of the reinsurance. The choice of path depends entirely on the company’s policy and type of insurance.This paper considers the main types of reinsurance and their mathematical models. An analysis of the probability of bankruptcy and the optimal use of a particular type of reinsurance are provided.There are also some examples and main results of research on this topic. After all, today the insurance industry is actively gaining popularity both in Ukraine and around the world. Accordingly, with a lot of competition, every insurer wants to get the maximum profit with minimal e↵ort.

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21

Khenien, A., A. Benattayallah, and G. Tabor. "CFD Simulation of an Industrial Spiral Refrigeration System." Energies 12, no. 17 (August 30, 2019): 3358. http://dx.doi.org/10.3390/en12173358.

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In the food industry, heating and cooling are key processes where CFD can play an important role in improving quality, productivity and reducing energy costs. Cooling products after baking is crucial for storage and transportation; the product has to be cooled efficiently to a specified temperature (often to fulfill regulatory requirements) whilst preserving its quality. This study involves the analysis of spiral cooling refrigerators used in cooling food products, in this case, Cornish Pasties. Three separate sets of CFD models were developed and validated against experimental data taken in the laboratory and measurements taken in use in industry. In the first set of models a full CFD model was developed of a refrigeration spiral including the pasties, and used to study the heat transfer from the products to the air. Further simulations were carried out on individual pasties to explore the pasty cooling and heat transfer to the air in more detail, with the pasty geometry being determined from MRI scans. In the final set of simulations, Image Based Meshing (IBM) was used to determine the interior structure of the pasty and develop a full heat conduction model of the interior, which was compared with separate laboratory experiments using jets of cold air to cool the pasty. In all cases, good agreement was obtained between the CFD results and experimental data, whilst the CFD simulations provide valuable information about the air flows and cooling in the industrial system.

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Liu, Yan Ling, Ling Qun Wang, and Zai Zhong Xia. "Design and Performance Study of a Novel Refrigeration System." Advanced Materials Research 354-355 (October 2011): 819–27. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.819.

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In order to solve the problems of pressure drop and leakage in the refrigerant circuit, a novel continuous adsorption system suited to use low heat source (75-85 oC) was designed and set up. To analyze and compare with the conventional system to reveal the similarity and difference, this paper sets up the mathematical models for these two systems. The adsorbers, condensers and evaporators in these two systems are exactly the same and the two systems are compared by working at the identical conditions, which is not feasible in real experimental lab. All the parameters and models used in this calculation are based on experimental results. Analysis demonstrates that the two kinds of system have very close performances, that is, the novel system has a relatively higher cooling capacity while the conventional system has a relatively higher COP.

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LESLIE, F. M., and I. W. STEWART. "Editorial. Mathematical models of liquid crystals." European Journal of Applied Mathematics 8, no. 3 (June 1997): 251–52. http://dx.doi.org/10.1017/s0956792597003082.

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A symposium held in Durham in July 1995 brought together an international collection of key mathematicians, theoretical physicists and experimentalists in the areas of liquid crystals and polymeric systems. Many of the participants met together for the first time, and the symposium stimulated new collaborative interactions among applied mathematicians and others who, prior to this meeting, were working separately on either liquid crystals or polymer fluids. The symposium also enhanced further interchanges of ideas between industry and academia. The flavour of this meeting is captured by the contents of this special issue which resulted from presentations given by invited speakers.

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Liu, Yan Ling, Xue Zeng Shi, and Yuan Yu. "Mathematical Analysis on a Special Adsorption Refrigeration System Suitable for Solar Energy System." Advanced Materials Research 953-954 (June 2014): 119–22. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.119.

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s. In this paper, a new adsorption refrigeration system is designed and calculated. In this system, there are two beds, two condensers and two evaporators. The working principle is explained and specified in this paper. And mathematical models are also set up and through calculation, the system performance is analyzed and evaluated.Theory study results demonstrate that the new system nearly has the same cooling capacity as conventional system and this kind of system can be adopted in actual use.

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Huang, Yanjun, Amir Khajepour, Farshid Bagheri, and Majid Bahrami. "Modelling and optimal energy-saving control of automotive air-conditioning and refrigeration systems." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 3 (August 5, 2016): 291–309. http://dx.doi.org/10.1177/0954407016636978.

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Air-conditioning and refrigeration systems are extensively adopted in homes, industry and vehicles. An important step in achieving a better performance and a higher energy efficiency for air-conditioning and refrigeration systems is a control-based model and a suitable control strategy. As a result, a dynamic model based on the moving-boundary and lumped-parameter method is developed in this paper. Unlike existing models, the proposed model lumps the effects of the fins into two equivalent parameters without adding any complexity and considers the effect produced by the superheated section of the condenser, resulting in a model that is not only simpler but also more accurate than the existing models. In addition, a model predictive controller is designed on the basis of the proposed model to enhance the energy efficiency of the air-conditioning and refrigeration systems. Simulations and experimental results are presented to demonstrate the accuracy of the model. The experiments show that an energy saving of about 8% can be achieved by using the proposed model predictive controller compared with the conventional on–off controller under the examined scenario. The better performance of the proposed controller requires electrification of the automotive air-conditioning and refrigeration systems so as to eliminate the idling caused by running the air-conditioning and refrigeration systems when a vehicle stops.

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Dantas, Tarcísio Soares Siqueira, Ivan Carlos Franco, Ana Maria Frattini Fileti, and Flávio Vasconcelos da Silva. "Nonlinear System Identification of a Refrigeration System." International Journal of Air-Conditioning and Refrigeration 24, no. 04 (December 2016): 1650024. http://dx.doi.org/10.1142/s2010132516500243.

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Applications of advanced control algorithms are important in the refrigeration field to achieve low-energy costs and accurate set-point tracking. However, the designing and tuning of control systems depend on dynamic mathematical models. Approaches like analytical modeling can be time-consuming because they usually lead to a large number of differential equations with unknown parameters. In this work, the application of system identification with the fast recursive orthogonal least square (FROLS) algorithm is proposed as an alternative to analytical modeling to develop a process dynamic model. The evaporating temperature (EVT), condensing temperature (CDT) and useful superheat (USH) are the outputs of interest for this system; covariance analysis of the candidate inputs shows that the model should be single-input–single-output (SISO). Good simulation results are obtained with two different validation data, with average output errors of 0.0343 (EVT model), 0.0079 (CDT model) and 0.1578 (USH model) for one of the datasets, showing that this algorithm is a valid alternative for modeling refrigeration systems.

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OVCHYNNIKOVA, OLENA, and GRAZYNA KACICKA. "TREND MODELS OF FOREST INDUSTRY INDICATORS." MODELING THE DEVELOPMENT OF THE ECONOMIC SYSTEMS 2, no. 2 (August 2021): 25–32. http://dx.doi.org/10.31891/mdes/2021-2-4.

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The article analyzes the main indicators of the forest industry of Ukraine and Khmelnytsky region. The state of timber harvesting by types of products is shown, it is noted that since 2017 there is no financing of the forest industry by the state, so forestries have to manage independently from their own sources. The paper considers the problem of modeling the indicators of the forest industry of the regions with the help of economic and mathematical methods and models. Trend models have been chosen as a research tool, with the help of which the equations of power, logistic, exponential dependences and polynomials of the second and third degrees are obtained. The constructed models are evaluated according to the criteria of determination and the forecast values for the following periods are determined. The results of calculations can be used in management decision-making systems as a source of data for further calculations. The obtained forecasts of forest industry indicators showed the importance of investing in the forest industry. Preservation, rational use and increase of resources of the forest treasury - so it is possible to define the main tasks facing the forestry of Ukraine. The issue of reforestation, creation of forest plantations in the volumes exceeding fellings, improvement of their qualitative structure and productivity remains paramount in the importance and urgency. Given the current situation in the country's forestry and in order to solve the problem of ecologically balanced forest management as a factor of sustainable socio-economic development, it is necessary to apply a comprehensive approach based on the use of economic and mathematical methods and models. This allows you to take into account technical, economic, environmental, organizational, social and other aspects of management, as well as see their relationship. One of the means of balanced management is modeling and forecasting trends in the main indicators of the forest industry both at the regional level and in the country as a whole.

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Zhao, Shibo, Yonghui Zhang, Yunqi Nie, Pengyu Qu, and Wenqiang Sun. "Performance of an internet data center refrigeration system using an evaporative cooler." E3S Web of Conferences 194 (2020): 01027. http://dx.doi.org/10.1051/e3sconf/202019401027.

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The traditional refrigeration method of internet data center (IDC) is mostly air refrigeration, which has undesired cooling effect and high power consumption. This study addresses this problem and proposes an evaporative air cooler (EAC) suitable for IDC. Given the high specific heat capacity of water, the evaporative condensing coil and spray device are added to the evaporative cooler to enhance the heat transfer effect. Heat and mass transfer mathematical models are established to analyze the heat transfer performance. The mathematical model is used to simulate the profile of the heat and mass transfer coefficient of the EAC with the amount of spray water and air flow. The results show that when the air flow changes from 10 to 20 kg/s, the air equivalent heat transfer coefficient increases by about 41%. When the air flow rate is 20 kg/s and the spray water volume is 0.00124 kg/(mꞏs), the total heat transfer coefficient is increased by about 308% compared with the case without spray water.

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29

Sitotaw, Natnale. "Energy and Exergy Analysis of Single Effect Water-LiBr Vapour Absorption Refrigeration System." International Journal of Advanced Science Computing and Engineering 4, no. 3 (December 11, 2022): 175–87. http://dx.doi.org/10.30630/ijasce.4.3.94.

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Vapor absorption refrigeration system (VARS) is one of the emerging technology in thermal-driven refrigeration systems and has too many benefits in comparison with another cooling system as their performance is good and the cost is low. Different mathematical models of various complexities have been developed for performance analysis, optimization, and design of such systems. In this study energy and exergy of a single effect LiBr vapor absorption refrigeration system is analyzed with different mathematical model developed so far. The effect of varying the temperature for each component of the system on the coefficient of performance (COP) and exergetic efficiency (COPex) is briefly discussed. The results show that increasing generator temperature from 86oc to 102oc for constant refrigerant mass flow rate causes COP of the system to increase, due to the decrease in circulation ratio. In another case, increasing the evaporator temperature from 2oc to 14oc for a constant temperature input of the generator has a positive effect on both the first and second law efficiency of the VARS as the load on the generator decrease. From the result, it can also be concluded that increasing absorber temperature has a negative impact on both COP and exergetic efficiency of VARS.

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30

Al-Hemeri, Dr Shurooq Talib, Dr Mumtaz A. Yousif, and Dr Ahmed M. AL Barifcani. "Optimization of Ethylene Refrigeration System Using Genetic Algorithms Method." Journal of Petroleum Research and Studies 7, no. 1 (May 6, 2021): 1–37. http://dx.doi.org/10.52716/jprs.v7i1.157.

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Ethylene refrigeration for gases separation at low temperature and high pressure for olefin production is an important technique in the chemical industry. Since small changes in the operating conditions of such a process can have a significant influence on its economics, optimization is desirable. The present work was aimed to propose and establish a mathematical model for the ethylene refrigeration system of the ethylene plant in Basrah petrochemical complex NO.1 (PC1) and reformulated as a geometric programming problem using Visual Basic for predicting:- (overall efficiency of the ethylene refrigeration system {% }and percent of energy saving %E). Through the formulated model shaft work consumption by the centrifugal compressor, refrigeration effect and coefficient of performance of the system were obtained and other parameters concerning the system. The results of simulation showed a good agreement with the manufacturer manual.In this study the effect of four factors as independent variables on the overall refrigeration system efficiency and percent of energy saving were studied ;evaporator low pressure (PL) in the range of (1-3)bar ,compressor discharge high pressure (Ph) in the range of ( 28-32)bar ,condenser degree of sub-cool temperature (Tsub-D) in the range of (6-22)0C and evaporator degree of superheat temperature (Tsup-D) in the range of (1-5)0C. And the optimum conditions that aimed to minimize the thermodynamic irreversibility i.e (maximize overall refrigeration system efficiency) and also lower operating cost i.e (maximize percent of energy saving) evaporator low pressure (PL) (2.8 bar), compressor discharge high pressure (Ph) (28.7 bar), condenser degree of sub-cool temperature (Tsub-D) (190C), and evaporator degree of superheat temperature (Tsup-D) (3.40C). At these conditions the overall refrigeration system efficiency is (81.8%) and percent of energy saving is 51.18% with respect to conditions in the factory.

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31

Dumitrascu, Gheorghe, Michel Feidt, and Stefan Grigorean. "Closed Irreversible Cycles Analysis Based on Finite Physical Dimensions Thermodynamics." Proceedings 58, no. 1 (September 11, 2020): 37. http://dx.doi.org/10.3390/wef-06905.

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The paper develops generalizing entropic approaches of irreversible closed cycles. The mathematical models of the irreversible engines (basic, with internal regeneration of the heat, cogeneration units) and of the refrigeration cycles were applied to four possible operating irreversible trigeneration cycles. The models involve the reference entropy, the number of internal irreversibility, the thermal conductance inventory, the proper temperatures of external heat reservoirs unifying the first law of thermodynamics and the linear heat transfer law, the mean log temperature differences, and four possible operational constraints, i.e., constant heat input, constant power, constant energy efficiency and constant reference entropy. The reference entropy is always the entropy variation rate of the working fluid during the reversible heat input process. The amount of internal irreversibility allows the evaluation of the heat output via the ratio of overall internal irreversible entropy generation and the reference entropy. The operational constraints allow the replacement of the reference entropy function of the finite physical dimension parameters, i.e., mean log temperature differences, thermal conductance inventory, and the proper external heat reservoir temperatures. The paper presents initially the number of internal irreversibility and the energy efficiency equations for engine and refrigeration cycles. At the limit, i.e., endoreversibility, we can re-obtain the endoreversible energy efficiency equation. The second part develops the influences between the imposed operational constraint and the finite physical dimensions parameters for the basic irreversible cycle. The third part is applying the mathematical models to four possible standalone trigeneration cycles. It was assumed that there are the required consumers of the all useful heat delivered by the trigeneration system. The design of trigeneration system must know the ratio of refrigeration rate to power, e.g., engine shaft power or useful power delivered directly to power consumers. The final discussions and conclusions emphasize the novelties and the complexity of interconnected irreversible trigeneration systems design/optimization.

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32

Parreño, F., and R. Alvarez-Valdes. "Mathematical models for a cutting problem in the glass manufacturing industry." Omega 103 (September 2021): 102432. http://dx.doi.org/10.1016/j.omega.2021.102432.

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33

Farley, Alan A. "Mathematical Programming Models for Cutting-Stock Problems in the Clothing Industry." Journal of the Operational Research Society 39, no. 1 (January 1988): 41. http://dx.doi.org/10.2307/2581997.

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34

Schwartz, Zvi. "Research: Game Theory: Mathematical Models Provide Insights into Hospitality Industry Phenomena." Journal of Hospitality & Tourism Research 21, no. 1 (February 1997): 48–70. http://dx.doi.org/10.1177/109634809702100106.

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Game theory is a mathematical modeling tool that considers the interaction among participants in economic activity. This article introduces some of the basic concepts of game theory, and demonstrates its applicability to hospitality industry research. The paper discusses essential elements of a game such as players, actions, strategies, payoffs and equilibria. The author explains how the information structure of a game determines its outcome, and examines the solution concepts of Nash Equilibrium in a simultaneous game. The Leader-Follower game and the concept of mixed strategies are also introduced. The study identifies topics currently discussed in the hospitality literature that are likely to benefit from this methodology. The discussion covers themes such as product differentiation and room rate policies, reputation and service quality, mergers and acquisitions and franchising.

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35

Farley, Alan A. "Mathematical Programming Models for Cutting-Stock Problems in the Clothing Industry." Journal of the Operational Research Society 39, no. 1 (January 1988): 41–53. http://dx.doi.org/10.1057/jors.1988.6.

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36

Ignatenko, V., and E. Bavbel. "The use of a linear mathematical models In the timber industry." Актуальные направления научных исследований XXI века: теория и практика 2, no. 4 (October 9, 2014): 221–24. http://dx.doi.org/10.12737/4745.

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37

Ansari, F. A. "Simplified and Accurate Mathematical Model for the Analysis of Heat and Moisture Transfer From Food Commodities." Journal of Heat Transfer 120, no. 2 (May 1, 1998): 530–33. http://dx.doi.org/10.1115/1.2824285.

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The present paper deals with a simple and accurate mathematical model for making reliable heat and mass transfer analyses from high-water–content solids when exposed to a cold air stream. Such physical situations are encountered in the refrigeration industry during air blast cooling of food commodities. The concept of enthalpy potential has been used to develop a simple linear surface boundary condition equation. This equation accounts for the cooling effect due to sensible convective heat transfer as well as the latent cooling effect due to produce desiccation. Investigations on ten fresh samples each of ripe tomato and cucumber established that there is a good agreement between the computed temperatures from the proposed model and the experimentally measured values.

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38

Koshova, Svitlana, Igor Britchenko, and Maksym Bezpartochnyi. "Economic and mathematical models for forecasting the development of the space industry." VUZF Review 6, no. 4 (December 27, 2021): 33–41. http://dx.doi.org/10.38188/2534-9228.21.4.04.

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The article examines a problem relevant to the national security of the state, the possibility of applying economic and mathematical models to predict the prospects for the development of the space industry. In modern conditions the, space industry is seen as the basis for innovative development and economic security of the state, which is the driving force of economic development. After all, in order to sustainably develop the economy and achieve the indicators planned by the government, it is necessary to have a clear idea of the mechanisms and function of the system as a whole and its individual parts. That is why competent forecasting of the main indicators of the development of the space industry with the identification of key factors influencing it is especially relevant at the present stage. Forecasting of indicators, based on the construction of economic and mathematical models of industry development. It is determined that the construction of this model begins with the development of a specification of the model, which includes a verbal description of the study, followed by a presentation of the process of its operation in the form of mathematical formulas. It is important to clearly formulate and define the problem, as well as to identify all the factors and patterns that characterize the functioning of the system. Economic and mathematical models can increase the efficiency of the planning system of the industry and increase the accuracy of the process of forecasting its development. The successful development of the space industry today becomes a necessary condition for preserving national sovereignty both in the military-political aspect and in the field of information security.

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39

Polyakova, Marina, and Alexey Korchunov. "Methodology of Developing Mathematical Models for Quality Indices Control." Applied Mechanics and Materials 598 (July 2014): 643–46. http://dx.doi.org/10.4028/www.scientific.net/amm.598.643.

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It is proposed to set the structure of metal products quality as a hierarchical tree of properties. Input and output variables and also control parameters of technological processes are represented as universal multitudes in formalization of the process of production quality indices handling in hardware industry technologies. Presence of simultaneously diversified information initiating different types of independence, is characteristic of solving problems of metal products quality indices control.

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40

Meena, Ayush, Tushar Sharma, Mohit Patodiya, and P. V. Ramana. "Evaluation of Morsel Rubber Mathematical Models in Seismic Areas." Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, no. 1 (December 19, 2022): 1185–91. http://dx.doi.org/10.38208/acp.v1.638.

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Reinforced concrete is the most consumed material in the world, followed by air and water. As the demand for reinforced concrete as a building material increases, so makes the demand for Portland cement and ordinary cement. On the other hand, environmental protection has become a significant issue due to climate change caused by global warming. This is due to emissions of greenhouse gases such as CO2 from human activities. Of all greenhouse gases, CO2 is responsible for approximately 65% ??of global warming. The cement industry also contributes to releasing CO2 into the atmosphere by producing large amounts of Portland cement and releasing large amounts of CO2. One can need to protect the environment by preventing the uncontrolled disposal of waste. Several efforts have been made to solve this problem. These include using additional cementitious materials such as fly ash, silica fume, granular blast furnace slag, rice husk ash, grass, metakaolin, and alternative binders to Portland cement. Consumption of morsel rubber concrete can reduce the environmental impact in the cement industry. From the perspective of global warming, the technology of self-compacting morsel rubber concrete can significantly reduce the emission of CO2 into the atmosphere. This report presents the analysis and test results of the properties of class 40 self-compacting Morsel rubber concrete using various new approaches.

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41

Dandoutiya, Bhrant, and Arvind Kumar. "Comparison of mathematical models to estimate the thermal conductivity of titanium oxide-water based nanofluid: A review." Thermal Science, no. 00 (2021): 224. http://dx.doi.org/10.2298/tsci201026224d.

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Heat transfer is a desirable phenomenon in many industries such as in refrigeration, transportation, power generation, cell preservation, incubator, metallurgy and material processing, health services, etc. Different types of fluids like water, oil, ethylene glycol etc are being used as a heat transfer medium. Water is a commonly used as working fluid for transfer of heat. Nanofluids are developed by adding nano sized particle(s) in existing fluid to improve the heat transfer rate. Thermal conductivity of the nanofluid is an important parameter in estimation of heat transfer rate. Different types of mathematical models were developed by various investigators to predict the thermal conductivity of the nanofluids. In this review paper,the theoretical and mathematical model(s) have been compared to predict the thermal conductivity of nanofluids. The experimental data have been collected from literature and compared with Maxwell model, Hamilton and crosser(H-C) model, Maxwell-Garnetts(MG) model, Pak cho model, Timofeeva et al. model, Li and Peterson model, Bhattacharya et al. model respectively in detail. It has been observed that the prediction wih the help of the mathematical models is good when the value of volume fraction was less than 0.01.

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42

Kukla, Mateusz, Krzysztof Talaśka, and Ireneusz Malujda. "Mathematical models used to describe the properties of magneto-rheological elastomers." AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 20, no. 1-2 (February 28, 2019): 398–402. http://dx.doi.org/10.24136/atest.2019.074.

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The paper presents and discusses mathematical models that are most widely used to describe the properties of magnetorheological elastomers (MREs). Magnetic elastomers are non-traditional engineering materials with an ever increasing number of practical applications in various areas of industry including transport..

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43

Ravand, Zahra Ghorbani, and Qi Xu. "Evaluation of Mathematical Models in Sustainable Supply Chain Management: Gap Analysis." International Business Research 14, no. 10 (August 31, 2021): 25. http://dx.doi.org/10.5539/ibr.v14n10p25.

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The main purpose of this paper is to present a comprehensive view of the application mathematical models in the designing and implementing SSCM beside to solving problems and making decision.  The research questions are: what kind of mathematical models are used for designing and implementing sustainable supply chain management, how to use them, which industries implemented in, what modules of SSCM depth in and finally finding the gaps between the goals of Sustainable development and current researches and suggestions for further researches. The methodology of the research is Systematic Literature review and evaluation peer review papers which are published in high ranking journals: First, we gather all papers through scientific data bases like Scopus, science direct, MDPI, Springer, Google Scholar. Then, screening papers based on the criteria such as object of paper, subject of paper, journals impact factor, peer review paper, and relative content of the papers. Finally, we selected 245 papers through three steps screening from 2806 papers that they have enough quality and relative to our research goals for context analysis. For context analysis: First we categorize the information of the papers and draw the current situation of researches in the framework of our topic. Then, we evaluate and compare the goals of sustainability and current situation and find the gapes, then, offer suggestions required researches for pollutant industries such as Casting Industry, Heavy Industry, Coal Industry and so on. On the other hand, there are gaps in researches in some modules of SSCM such as packaging, designing products, etc.    

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44

McCONNELL, JENNIFER A., and DONALD W. SCHAFFNER. "Validation of Mathematical Models for Salmonella Growth in Raw Ground Beef under Dynamic Temperature Conditions Representing Loss of Refrigeration." Journal of Food Protection 77, no. 7 (July 1, 2014): 1110–15. http://dx.doi.org/10.4315/0362-028x.jfp-14-038.

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Temperature is a primary factor in controlling the growth of microorganisms in food. The current U.S. Food and Drug Administration Model Food Code guidelines state that food can be kept out of temperature control for up to 4 h without qualifiers, or up to 6 h, if the food product starts at an initial 41°F (5°C) temperature and does not exceed 70°F (21°C) at 6 h. This project validates existing ComBase computer models for Salmonella growth under changing temperature conditions modeling scenarios using raw ground beef as a model system. A cocktail of Salmonella serovars isolated from different meat products (Salmonella Copenhagen, Salmonella Montevideo, Salmonella Typhimurium, Salmonella Saintpaul, and Salmonella Heidelberg) was made rifampin resistant and used for all experiments. Inoculated samples were held in a programmable water bath at 4.4°C (40°F) and subjected to linear temperature changes to different final temperatures over various lengths of time and then returned to 4.4°C (40°F). Maximum temperatures reached were 15.6, 26.7, or 37.8°C (60, 80, or 100°F), and the temperature increases took place over 4, 6, and 8 h, with varying cooling times. Our experiments show that when maximum temperatures were lower (15.6 or 26.7°C), there was generally good agreement between the ComBase models and experiments: when temperature increases of 15.6 or 26.7°C occurred over 8 h, experimental data were within 0.13 log CFU of the model predictions. When maximum temperatures were 37°C, predictive models were fail-safe. Overall bias of the models was 1.11. and accuracy was 2.11. Our experiments show the U.S. Food and Drug Administration Model Food Code guidelines for holding food out of temperature control are quite conservative. Our research also shows that the ComBase models for Salmonella growth are accurate or fail-safe for dynamic temperature conditions as might be observed due to power loss from natural disasters or during transport out of temperature control.

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45

Haida, Michal, Rafal Fingas, Wojciech Szwajnoch, Jacek Smolka, Michal Palacz, Jakub Bodys, and Andrzej Nowak. "An Object-Oriented R744 Two-Phase Ejector Reduced-Order Model for Dynamic Simulations." Energies 12, no. 7 (April 3, 2019): 1282. http://dx.doi.org/10.3390/en12071282.

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The object-oriented two-phase ejector hybrid reduced-order model (ROM) was developed for dynamic simulation of the R744 refrigeration system. OpenModelica software was used to evaluate the system’s performance. Moreover, the hybrid ROM results were compared to the results given by the non-dimensional and one-dimensional mathematical approaches of the R744 two-phase ejector. Accuracy of all three ejector models was defined through a validation procedure for the experimental results. Finally, the dynamic simulation of the hybrid ROM ejector model integrated with the R744 refrigeration system was presented based on the summer campaign at three different climate zones: Mediterranean, South American and South Asian. The hybrid ROM obtained the best prediction of ejector mass flow rates as compared with other ejector models under subcritical and transcritical operating conditions. The dynamic simulations of the R744 ejector-based system indicated the ejector efficiency variations and the best efficiency at the investigated climate zones. The coefficient of performance (COP) varied from 2.5 to 4.0 according to different ambient conditions. The pressure ratio of 1.15 allowed a more stabilised system during the test campaign with an ejector efficiency from 20% to over 30%.

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46

Muhammad, Hafiz Ali, Hafiz Muhammad Abdullah, Zabdur Rehman, Beomjoon Lee, Young-Jin Baik, Jongjae Cho, Muhammad Imran, Manzar Masud, Mohsin Saleem, and Muhammad Shoaib Butt. "Numerical Modeling of Ejector and Development of Improved Methods for the Design of Ejector-Assisted Refrigeration System." Energies 13, no. 21 (November 9, 2020): 5835. http://dx.doi.org/10.3390/en13215835.

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An ejector is a simple mechanical device that can be integrated with power generation or the refrigeration cycle to enhance their performance. Owing to the complex flow behavior in the ejector, the performance prediction of the ejector is done by numerical simulations. However, to evaluate the performance of an ejector integrated power cycle or refrigeration cycle, the need for simpler and more reliable thermodynamic models to estimate the performance of the ejector persists. This research, therefore, aims at developing a single mathematical correlation that can predict the ejector performance with reasonable accuracy. The proposed correlation relates the entrainment ratio and the pressure rise across the ejector to the area ratio and the mass flow rate of the primary flow. R141b is selected as the ejector refrigerant, and the results obtained through the proposed correlation are validated through numerical solutions. The comparison between the analytical and numerical with experimental results provided an error of less than 8.4% and 4.29%, respectively.

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47

Di Mattia, Edoardo, Agostino Gambarotta, Mirko Morini, and Costanza Saletti. "Application of modelling approaches of twin-screw compressors: thermodynamic investigation and reduced-order model identification." E3S Web of Conferences 312 (2021): 05001. http://dx.doi.org/10.1051/e3sconf/202131205001.

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Refrigeration is an essential part of the food chain. It is used in all stages of the chain, from industrial food processing to final consumption at home. In these processes, mechanical refrigeration technologies are employed, where compressors increase gas pressure from evaporation to condensation. In industrial refrigeration systems, twin-screw compressors represent the most widely used technology. A detailed mathematical model of a twin-screw compressor has been developed in Simulink® using differential equations for energy and mass balances to simulate the compression cycle that includes suction, compression and discharge phases. Gas pressure and enthalpy can be calculated as time functions during the cycle. However, the computational times obtained limit the possibility to extend the use of the model in the development of control strategies for the whole refrigeration plant in its real operating conditions. Therefore, the detailed model has been used to train a simplified model developed in Matlab®: the simulated mass flow rate, shaft power and the fluid discharge temperature have been employed to identify several geometrical and thermodynamic parameters of the simplified model. The latter relies on non-linear algebraic equations and, thus, requires a very short computational time. A limited performance dataset has been used to train the model, and a different dataset to test it: the results of the models have been compared, and small errors in mass flow rate, shaft power and fluid discharge temperature have been observed.

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48

Tsai, Wen-Hsien. "Green Production Planning and Control for the Textile Industry by Using Mathematical Programming and Industry 4.0 Techniques." Energies 11, no. 8 (August 9, 2018): 2072. http://dx.doi.org/10.3390/en11082072.

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The textile industry is one of the world’s major sources of industrial pollution, and related environmental issues are becoming an ever greater concern. This paper considers the environmental issues of carbon emissions, energy recycling, and waste reuse, and uses a mathematical programming model with Activity-Based Costing (ABC) and the Theory of Constraints (TOC) to achieve profit maximization. This paper discusses the combination of mathematical programming and Industry 4.0 techniques to achieve the purpose of green production planning and control for the textile industry in the new era. The mathematical programming model is used to determine the optimal product mix under various production constraints, while Industry 4.0 techniques are used to control the production progress to achieve the planning targets. With the help of an Industry 4.0 real-time sensor and detection system, it can achieve the purposes of recycling waste, reducing carbon emission, saving energy and cost, and finally achieving a maximization of profit. The main contributions of this research are using mathematical programming approach to formulate the decision model with ABC cost data and TOC constraints for the textile companies and clarifying the relation between mathematical programming models and Industry 4.0 techniques. Managers in the textile companies can apply this decision model to achieve the optimal product-mix under various constraints and to evaluate the effect on profit of carbon emissions, energy recycling, waste reuse, and material quantity discount.

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49

Carvalho, Ricardo Nolasco, Marcelo A. C. Ferreira, Dagoberto Brandão Santos, and Ronaldo Barbosa. "Mathematical Modeling of Microstructure Evolution of V Steels during Hot Rolling of Seamless Tubes." Materials Science Forum 638-642 (January 2010): 2537–42. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.2537.

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Torsion and compression testing have been used to simulate microstructure evolution of industry processes. Additionally, mathematical modeling of the industry hot rolling processes has been carried out by several researchers. These models employed equations published in the literature describing kinetics of softening, grain size evolution and grain growth. Validation of the models was carried, in some cases, by comparing the microstructure or the average stress per pass, the latter as calculated from industry rolling mill loads. In the present work, torsion simulation and industry trial results were used to validate the mathematical model presented. Equations used in the model were mostly taken from literature and appropriate modifications were implemented concerning basically two points: a) the transfer time between CMM and SRM, a step in the production line typical for seamless rolling and rather unusual for other industry rolling processes and b) the chemical composition used in tube rolling industry where C equivalent values are usually higher than those used in the rolling of flats.

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50

Kruzhilko, O., N. Volodchenkova, V. Maystrenko, B. Bolibrukh, V. Kalinchyk, A. Zakora, A. Feshchenko, and S. Yeremenko. "Mathematical modelling of professional risk at Ukrainian metallurgical industry enterprises." Journal of Achievements in Materials and Manufacturing Engineering 1, no. 108 (September 1, 2021): 35–41. http://dx.doi.org/10.5604/01.3001.0015.4797.

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Purpose: To develop a more advanced methodology, the application of which will provide an informational and computational and analytical basis for planning and implementing effective preventive measures aimed at minimizing occupational risks with limited resources, as well as in the absence of organizational and technical capabilities to create absolutely safe working conditions Design/methodology/approach: For the study, statistical data were used that obtained from enterprises of the metallurgical industry of Ukraine. Research methods: analysis and generalization of known scientific results, methods of statistical analysis, mathematical modelling, expert assessments and decision theory. Findings: The results of experimental studies have confirmed the possibility of an objective assessment of various options for the OSH management strategy, which allows justifying the allocation of funds for OSH in the required amounts. It is shown that professional risk management strategies are characterized by different efficiency in the use of available financial resources, and the most effective strategy is one that allows you to minimize the level of risk (in comparison with other strategies) with the same amount of funding. Research limitations/implications: The study focuses on enterprises of the metallurgical industry in Ukraine. Practical implications: The application of the developed mathematical models demonstrates the effectiveness of financing certain preventive and protective measures, and stimulates the head to ensure industrial safety. Originality/value: The developed mathematical models allow justifying the allocation of funds for OSH in the required amounts.

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