Journal articles on the topic 'Coast changes – Mathematical models'
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1
Montoya, Germán A., and Yezid Donoso. "Delay-Sensitive Optimization Models and Distributed Routing Algorithms for Mobile Wireless Sensor Networks." International Journal of Computers Communications & Control 11, no. 6 (October 17, 2016): 819. http://dx.doi.org/10.15837/ijccc.2016.6.2745.
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Communication disruptions caused by mobility in wireless sensor networks introduce undesired delays which affect the network performance in delay sensitive applications in MWSN. In order to study the negative effects caused by mobility, we propose two mathematical models to find the minimum cost path between a source node and a destination node considering the nodes position changes across time. Our mathematical models consider the usage of buffers in the nodes to represent the fact of storing a message if there is not an appropriate forwarding node for transmitting it. In order to contrast our mathematical models results we have designed two kinds of algorithms: the first one takes advantage of the closest neighbours to the destination node in order to reach it as fast as possible from the source node. The second one simply reaches the destination node if a neighbour node is precisely the destination node. Finally, we compare the delay performance of these algorithms against our mathematical models to show how efficient they are for reaching a destination node. This paper is an extension of [10].a The mathematical model proposed in [10] is improved by adding two new binary variables with the aim of make it more readable and compact mathematically. This means a post-processing algorithm is added only for evaluating if a solution is at the first network state.
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Head, R., D. Shepherd, G. Butt, and G. Buck. "OTTER mathematical process simulation of potable water treatment." Water Supply 2, no. 1 (January 1, 2002): 95–101. http://dx.doi.org/10.2166/ws.2002.0012.
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Process modelling has been used for many years in the chemical engineering field and more recently has become well established for as a tool for analysing and optimising the performance of wastewater treatment works. In the clean water area, models are routinely used for simulating distribution networks. In contrast, however, the use of modelling tools on potable water treatment works is relatively new and has yet to become well established. A range of tools have been suggested, including artificial neural networks, computational fluid dynamics and process simulation. WRc have developed a dynamic simulation package for predicting the performance of water treatment works, via models of individual processes. The software has a range of uses, including process and works optimisation, operational decision support, as a design aid and for training engineers and operators. The models are dynamic so that they predict the response of the treatment works to changes in flow, raw water quality and process operating conditions. The software has been used in a wide variety of applications, including optimising process plant operation to minimise cost and to investigate the reasons why a treatment works failed to meet its design criteria at the maximum design throughput.
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CHANG, HORNG-JINH, and WEN-FENG LIN. "A SIMPLE SOLUTION METHOD FOR THE FINITE HORIZON EOQ MODEL FOR DETERIORATING ITEMS WITH COST CHANGES." Asia-Pacific Journal of Operational Research 28, no. 06 (December 2011): 689–704. http://dx.doi.org/10.1142/s0217595911003314.
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In this article, we generalize Lev and Weiss's (1990) finite horizon economic order quantity (EOQ) model with cost change to the inventory system with deterioration. Supplier announces some or all of cost parameters may change after a decided time. Depending on whether the inventory is depleted at the time of the last opportunity to purchase before some or all of the cost parameters may change, there are two types of inventory models to be discussed. The main objective of this paper is to identify the optimal ordering policy of the inventory system by comparing the minimum cost of the two types of models. We suggest a finite horizon EOQ model to combine the above two types and propose a theorem that can quickly identify the optimal policy of the suggested model. In considering temporary price discount problem and discrete-time EOQ problem, in general, there are integer operators in mathematical models, but our approach offers a closed-form solution to these kinds of problems. Numerical examples are presented to demonstrate the results of the proposed properties and theorem.
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Pourbakhshian, Somayyeh, and Majid Pouraminian. "Analytical Models for Optimal Design of a Trapezoidal Composite Channel Cross-Section." Civil and Environmental Engineering Reports 31, no. 1 (March 1, 2021): 118–38. http://dx.doi.org/10.2478/ceer-2021-0009.
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Abstract In this paper, several analytical models are presented for the optimal design of a trapezoidal composite channel cross-section. The objective function is the cost function per unit length of the channel, which includes the excavation and lining costs. To define the system, design variables including channel depth, channel width, side slopes, freeboard, and roughness coefficients were used. The constraints include Manning’s equation, flow velocity, Froude number, and water surface width. The Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm was used to solve the optimization problem. The results are presented in three parts; in the first part, the optimal values of the design variables and the objective function are presented in different discharges. In the second part, the relationship between cost and design variables in different discharges is presented in the form of conceptual and analytical models and mathematical functions. Finally, in the third part, the changes in the design variables and cost function are presented as a graph based on the discharge variations. Results indicate that the cost increases with increasing water depth, left side slope, equivalent roughness coefficient, and freeboard.
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Fang, Y., M. Huang, C. Liu, H. Y. Li, and L. R. Leung. "A generic biogeochemical module for earth system models." Geoscientific Model Development Discussions 6, no. 2 (June 13, 2013): 3211–40. http://dx.doi.org/10.5194/gmdd-6-3211-2013.
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Abstract. Physical and biogeochemical processes regulate soil carbon dynamics and CO2 flux to and from the atmosphere, influencing global climate changes. Integration of these processes into earth system models (e.g. community land models – CLM), however, currently faces three major challenges: (1) extensive efforts are required to modify modeling structures and to rewrite computer programs to incorporate new or updated processes as new knowledge is being generated, (2) computational cost is prohibitively expensive to simulate biogeochemical processes in land models due to large variations in the rates of biogeochemical processes, and (3) various mathematical representations of biogeochemical processes exist to incorporate different aspects of fundamental mechanisms, but systematic evaluation of the different mathematical representations is difficult, if not impossible. To address these challenges, we propose a new computational framework to easily incorporate physical and biogeochemical processes into land models. The new framework consists of a new biogeochemical module with a generic algorithm and reaction database so that new and updated processes can be incorporated into land models without the need to manually set up the ordinary differential equations to be solved numerically. The reaction database consists of processes of nutrient flow through the terrestrial ecosystems in plants, litter and soil. This framework facilitates effective comparison studies of biogeochemical cycles in an ecosystem using different conceptual models under the same land modeling framework. The approach was first implemented in CLM and benchmarked against simulations from the original CLM-CN code. A case study was then provided to demonstrate the advantages of using the new approach to incorporate a phosphorus cycle into the CLM model. To our knowledge, the phosphorus-incorporated CLM is a new model that can be used to simulate phosphorus limitation on the productivity of terrestrial ecosystems.
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Trad, Antoine. "An Applied Mathematical Model for Business Transformation and Enterprise Architecture." International Journal of Organizational and Collective Intelligence 11, no. 1 (January 2021): 1–25. http://dx.doi.org/10.4018/ijoci.2021010101.
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To restructure or transform a business organization in the optimal manner, there is a need for a specific organizational intelligence and engineering pattern to support a business transformation and integration strategy. The applied strategy should be based on existing standards, mapping concepts, and various levels of interoperability. Today, many standards, patterns, and methodologies exist, and they are very advanced and are able to support the organizational transformation process of the older business environment to become part of a larger business eco-system. Transforming a traditional organization or a business environment into an innovative and efficient organization based atomic service-oriented environment is a great challenge, because transformation initiatives often fail, mainly because of the monolithic nature of the mammoth-like organisations. Many monolithic environments and their correspondent business information and communication systems fail to be transformed and are unable to adapt to the new business requirements and challenges. These presented facts make organizations unable to follow frequent changes and this fact might cost organizations fortunes without obtaining the return on investment. A well-designed organizational transformation process and a reorganized business environment should be based on a platform of flexible atomic business loose block (or microartefacts) that can support the future changes request of the business environment. In order to reach the optimal organizational transformation models, an organizational engineering pattern must be designed to improve the functions of the existing business services. This article's goal is to present an organizational engineering and risk pattern integration concept is presented to support frequent change initiatives.
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ROMANCHENKO, Ihor S., Oleh SEMENENKO, Maryna SLIUSARENKO, Mykola VASIANOVYCH, and Ihor LEVCHENKO. "On the development of mathematical models for the reliability evaluation of aircraft operation in combat conditions." INCAS BULLETIN 13, S (August 3, 2021): 169–78. http://dx.doi.org/10.13111/2066-8201.2021.13.s.16.
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The authors of this study propose a methodological approach to modelling the reliability evaluation of aircraft operation in combat conditions. When developing recommendations on operational and strategic requirements for promising aircraft, a very important aspect is the elicitation of the requirements for their reliability, namely no-failure operation. Reliability as a parameter of any equipment should be set in the technical specifications for development together with other operational requirements in the form of reasonable quantitative indicators – reliability standards. The establishment of specific reliability standards stimulates its growth and creates the basis for rational design, taking into account the requirements of reliable operation. The analysis showed that different models can be used to simulate aircraft reliability. In this case, for example, the final values of mean time to failure (MTTF) would be different. The test results show that the methods and mathematical models used to substantiate the values of time and probability of trouble-free operation of aircraft do not fully correspond to the actual processes of changing their state during the use in the military. This is confirmed by a significant discrepancy in the values of reliability indicators implemented in practice. This was due to the fact that the acquainted mathematical models of aircraft reliability do not take into account the combat conditions in which they are supposed to operate. In addition, the reliability indicators used do not take into account possible changes (decrease) in these indicators during the period of aircraft operation. In general, the shortcomings inherent in the methods and mathematical models currently used to describe the aircraft reliability reduce the accuracy of the results obtained, and also do not quite adequately reflect the features of the corresponding process. When using different models, the cost of time to failure differs significantly. The more factors are taken into account, the greater the operating time to failure will be. This means that when designing aircraft, it is necessary to set the value of this indicator greater than indicated in the form. Taking into account additional factors complicates the model, but at the same time makes it more accurate.
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Kuz’min, A. Yu. "An Accounting Procedure for Bonds with a Double Currency Denomination in Accordance with the IFRS." Accounting. Analysis. Auditing 7, no. 6 (December 19, 2020): 55–63. http://dx.doi.org/10.26794/2408-9303-2020-7-6-55-63.
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The study is devoted to the development of accounting procedure and recording the financial results of bonds with a double currency denomination in accordance with International Financial Reporting standards (IFRS). The methodological base of the research includes system and dynamic-situational analysis, evaluation models of financial mathematics, accounting procedures of the theory of financial accounting. Based on the assumptions made at the formal mathematical level, this procedure is fully algorithmized, despite the ambiguity or impossibility of direct assessment of such basic accounting indicators as the initial estimate, the internal effective interest rate, and the amortized cost of a financial instrument. Considerable attention is paid to the issues of mathematical evaluation and reflection of financial results when preparing financial statements in accordance with the concept of amortized cost and effective interest rate, taking into account the impact of changes in the currency component in dynamics. The originality and uniqueness of the developed procedure is that it is applicable to the situations where coupon payments are paid several times a year. The theoretical and practical significance of the research is determined by the development of scientific and applied tools that include accounting and process models, evaluation algorithms and procedures that can be used by accounting and audit departments in practical work when solving problems of reporting in accordance with IFRS.
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Rocher, Javier, Mar Parra, Lorena Parra, Sandra Sendra, Jaime Lloret, and Jesús Mengual. "A Low-Cost Sensor for Detecting Illicit Discharge in Sewerage." Journal of Sensors 2021 (March 10, 2021): 1–16. http://dx.doi.org/10.1155/2021/6650157.
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The presence of illicit discharges in sewerage systems generates an important impact in wastewater treatment plants and the ecosystem. In this paper, we present two prototypes for monitoring the presence of solids in wastewater and to study the effect of the water height. The prototypes are based on color and infrared LEDs and two photosensors located in the prototypes at 0° and 180° degrees. When the photosensor is located at 180°, all color LEDs present a good range of output voltage (approximately 5 V to 0 V) and good R2. However, for the typical concentration of solids in wastewater, the prototypes do not work correctly. When the photosensor is located in the prototypes the LEDs, yellow, red, and white have a good operation with voltage differences of 1.73 V, 1.76 V, and 1.13 V in P1 and 1.58 V, 1.84 V, and 1.35 V in P2, respectively. We calculate the mathematical model with the heights and solid concentration. The mathematical models which do not consider height present good R2. In conclusion, when the photosensor is located in the prototype, the height does not have an important effect and can detect the illicit discharge of solids. When the photosensor is located at 180°, it can be used for water with important changes in solid concentrations.
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Fang, Y., M. Huang, C. Liu, H. Li, and L. R. Leung. "A generic biogeochemical module for Earth system models: Next Generation BioGeoChemical Module (NGBGC), version 1.0." Geoscientific Model Development 6, no. 6 (November 13, 2013): 1977–88. http://dx.doi.org/10.5194/gmd-6-1977-2013.
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Abstract. Physical and biogeochemical processes regulate soil carbon dynamics and CO2 flux to and from the atmosphere, influencing global climate changes. Integration of these processes into Earth system models (e.g., community land models (CLMs)), however, currently faces three major challenges: (1) extensive efforts are required to modify modeling structures and to rewrite computer programs to incorporate new or updated processes as new knowledge is being generated, (2) computational cost is prohibitively expensive to simulate biogeochemical processes in land models due to large variations in the rates of biogeochemical processes, and (3) various mathematical representations of biogeochemical processes exist to incorporate different aspects of fundamental mechanisms, but systematic evaluation of the different mathematical representations is difficult, if not impossible. To address these challenges, we propose a new computational framework to easily incorporate physical and biogeochemical processes into land models. The new framework consists of a new biogeochemical module, Next Generation BioGeoChemical Module (NGBGC), version 1.0, with a generic algorithm and reaction database so that new and updated processes can be incorporated into land models without the need to manually set up the ordinary differential equations to be solved numerically. The reaction database consists of processes of nutrient flow through the terrestrial ecosystems in plants, litter, and soil. This framework facilitates effective comparison studies of biogeochemical cycles in an ecosystem using different conceptual models under the same land modeling framework. The approach was first implemented in CLM and benchmarked against simulations from the original CLM-CN code. A case study was then provided to demonstrate the advantages of using the new approach to incorporate a phosphorus cycle into CLM. To our knowledge, the phosphorus-incorporated CLM is a new model that can be used to simulate phosphorus limitation on the productivity of terrestrial ecosystems. The method presented here could in theory be applied to simulate biogeochemical cycles in other Earth system models.
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Yeh, T. W., and R. Y. Chuang. "MORPHOLOGICAL ANALYSIS OF LANDSLIDES IN EXTREME TOPOGRAPHY BY UAS-SfM: DATA ACQUISITION, 3D MODELS AND CHANGE DETECTION." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B5-2020 (August 24, 2020): 173–78. http://dx.doi.org/10.5194/isprs-archives-xliii-b5-2020-173-2020.
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Abstract. Landslides are one major kind of natural disasters and geomorphological processes on Earth’s surface. Accurate geodetic observations are crucial for understanding morphological changes, providing a quantitative basis of further research in surface process and hazard management. In recent years, the development of UAVs and SfM technology enhance research to build high quality digital surface models of landforms with low budget and efficiency. In areas of extreme topography where landslides occur on steep slopes, however, it is required to specifically design the UAV-SfM workflow to keep the data quality. This study aims to use UAS-SfM workflow to develop a low-cost, efficient methodology to detect detailed morphological change of landslide morphology in extreme topography. The study focuses on examining results of different flight design and GCPs distribution geometry, which are important components in the workflow. In addition, we applied a mathematical model to compare point clouds to calculate volumetric change of the landslide with reduced distortion.
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Korobeinikov, Andrei, and Alex Mcnabb. "Long-term global climate dynamics: A Hopf bifurcation causing recurrent ice ages." Journal of Applied Mathematics and Decision Sciences 5, no. 4 (January 1, 2001): 201–14. http://dx.doi.org/10.1155/s1173912601000153.
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Rapid and dramatic changes in climate and glacial conditions have taken place during the last 2.5 million years of the earth's history. Huge ice sheets expanded and contracted periodically, at times covering large areas of North America and Europe. Global sea levels dropped and rose 100 m to 150 m in response to the growth and melting of glaciers, causing continental coast lines to move far into present sea areas and then retreated again. We will use a simple conceptual model to demonstrate that these climate and glacier fluctuations can be a consequence of a supercritical Hopf bifurcation in models of the “ocean-land-atmosphere” system.
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Azizah, Aulia, and Hendrata Wibisana. "ANALISA TEMPORAL SEBARAN SUHU PERMUKAAN LAUT TAHUN 2018 HINGGA 2020 DENGAN DATA CITRA TERRA MODIS." Jurnal Kelautan: Indonesian Journal of Marine Science and Technology 13, no. 3 (December 25, 2020): 196–205. http://dx.doi.org/10.21107/jk.v13i3.7550.
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ABSTRACTSea surface temperature (SPL) information is the most important water quality parameter in the ocean, especially in coastal areas. Remote sensing technology with Terra Modis satellite data is used for periodic monitoring of SPL changes. The purpose of this study was to analyze the temporal distribution of SPL on the coast of Malang, East Java. The data used are SPL data from Terra-MODIS satellite sensors in May 2018, 2019 and 2020. Analysis of the data used is descriptive analysis which includes temporal analysis of SPL based on SPL fluctuations in graphical form. The results showed that the temporal variation of the 2018-2020 SPL on the coast of Malang tends to increase. The SPL value in 2018 varies between 25 ° C - 26 ° C while in 2019 it varies between 26 ° C - 27 ° C and in 2020 it ranges between 30 ° C - 31 ° C. The highest average SPL value from 2018 - 2020 is in 2020 with a temperature of 30.58 ° C. In an effort to model sea surface temperatures used calculations using mathematical models. From the results obtained it can be concluded that the most optimal mathematical model is derived from the wavelength of 667 nm on May 23, 2020 with the equation model y = -0,498ln (x) + 27,936 which results in a correlation value of R = 0.6561.Keywords: sea surface temperature, terra modis, satellite, mathematical models.ABSTRAKInformasi suhu permukaan laut (SPL) merupakan parameter kualitas perairan yang paling penting di lautan terutama kawasan pesisir. Teknologi penginderaan jauh dengan data satelit Terra-MODIS digunakan untuk pemantauan perubahan SPL secara berkala. Tujuan penelitian ini adalah menganalisis sebaran temporal SPL di pesisir pantai Malang, Jawa Timur. Data yang digunakan adalah data SPL dari sensor satelit Terra Modis bulan Mei 2018, 2019 dan 2020. Analisis data yang digunakan adalah analisis deskriptif yang meliputi analisis SPL secara temporal berdasarkan fluktuasi SPL dalam bentuk grafik. Hasil penelitian menunjukan bahwa variasi temporal SPL tahun 2018-2020 di pesisir Malang cenderung mengalami peningkatan. Nilai SPL tahun 2018 bervariasi antara 25°C – 26°C sedangkan tahun 2019 bervariasi antara 26°C – 27°C dan tahun 2020 berkisar antara 30°C – 31°C. Nilai SPL rata-rata tertinggi dari tahun 2018 – 2020 berada pada tahun 2020 dengan suhu 30,58°C. Dalam upaya memodelkan suhu permukaan laut digunakan perhitungan dengan menggunakan model matematika. Dari hasil yang diperoleh dapat disimpulkan bahwa model matematis yang paling optimal berasal dari panjang gelombang 667 nm pada tanggal 23 Mei 2020 dengan model persamaan y = -0,498ln(x) + 27,936 yang menghasilkan nilai korelasi R = 0,6561.Kata Kunci: suhu permukaan laut, terra modis, satelit, model matematis.
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Hertwin, Minor P., Olivares-Benítez Elías, Tapia-Olvera Ruben, and Martínez Flores J. Luis. "Variations in the Flow Approach to CFCLP-TC for Multiobjective Supply Chain Design." Mathematical Problems in Engineering 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/816286.
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We review the problem for the design of supply chains called Capacitated Fixed Cost Facility Location Problem with Transportation Choices (CFCLP-TC). The problem is based on a production network of two echelons with multiple plants, a set of potential distribution centers, and customers. The problem is formulated as an optimization model with two objective functions based on time and cost. This paper proposes three changes to the original model to compare the sets of efficient solutions and the computational time required to obtain them. The main contribution of this paper is to extend the existing literature by incorporating approaches for the supply of product to customers through multiple sources, the direct flow between plants and customers, without this necessarily implying removing the distribution centers, and the product flow between distribution centers. From these approaches, we generate mathematical programming models and propose to solve through the epsilon-constraint approach for generating Pareto fronts and thus compare each of these approaches with the original model. The models are implemented in GAMS and solved with CPLEX.
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Dziugiel, Bartosz, and Zdobyslaw Jan Goraj. "From statistics, through new requirements to mathematical modelling of SAT aircraft safety." Aircraft Engineering and Aerospace Technology 90, no. 4 (May 8, 2018): 659–66. http://dx.doi.org/10.1108/aeat-01-2017-0027.
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Purpose The purpose of this study is to investigate the influence of the technical and operational specifications of the Small Aircraft Transport System (SAT/SATS) to the achieved safety level. Design/methodology/approach Safety estimation was made with the use of mathematical model of safety of light aircraft in commercial operations developed on the basis of Federal Aviation Administration (FAA) data. The analysis was conducted for two different SATS business models based on Direct AiR Transport (DART) concept. It allowed for the investigation of the impact of technical specifications of the aircraft included into the SATS fleet as well as the selected elements of the applied business model on SATS safety level. Findings It was found that the proposed changes to DART system resulted in a significant improvement of safety. Mean Time Between Incidents and Accident (MTBIA) increased by 200 per cent. Additionally, the introduced alterations impacted the weights of particular domains and pilot’s error became less critical than the technical reliability. Practical implications It was shown that the application of new requirements influences both the safety level and the cost of operation, which was demonstrated within the ESPOSA and DART projects. Additionally, it was indicated that further effort to improve the light aircraft safety is absolutely necessary. Originality/value Originality consists in combining in one mathematical model both the aircraft configuration and the rules for business operation. Optimization of selected parameters of the system leads to a significant reduction in the accident number and to keeping the cost increment at a reasonable level. It was also found that the resulted improvement sometimes cannot be sufficient to consider a small aircraft operation fully safe, mainly owing to the numerous restrictions because of its small weight and loading capacity.
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Fletcher, Alexander G., Philip J. Murray, and Philip K. Maini. "Multiscale modelling of intestinal crypt organization and carcinogenesis." Mathematical Models and Methods in Applied Sciences 25, no. 13 (September 17, 2015): 2563–85. http://dx.doi.org/10.1142/s0218202515400187.
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Colorectal cancers are the third most common type of cancer. They originate from intestinal crypts, glands that descend from the intestinal lumen into the underlying connective tissue. Normal crypts are thought to exist in a dynamic equilibrium where the rate of cell production at the base of a crypt is matched by that of loss at the top. Understanding how genetic alterations accumulate and proceed to disrupt this dynamic equilibrium is fundamental to understanding the origins of colorectal cancer. Colorectal cancer emerges from the interaction of biological processes that span several spatial scales, from mutations that cause inappropriate intracellular responses to changes at the cell/tissue level, such as uncontrolled proliferation and altered motility and adhesion. Multiscale mathematical modelling can provide insight into the spatiotemporal organisation of such a complex, highly regulated and dynamic system. Moreover, the aforementioned challenges are inherent to the multiscale modelling of biological tissue more generally. In this review we describe the mathematical approaches that have been applied to investigate multiscale aspects of crypt behavior, highlighting a number of model predictions that have since been validated experimentally. We also discuss some of the key mathematical and computational challenges associated with the multiscale modelling approach. We conclude by discussing recent efforts to derive coarse-grained descriptions of such models, which may offer one way of reducing the computational cost of simulation by leveraging well-established tools of mathematical analysis to address key problems in multiscale modelling.
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Maksimov, Sergey, Yury Vasin, Nikolai Valuyskov, and Kanat Utarov. "The Digitization of Criminal Policy as a Tool of Overcoming its Unsystematicity." Russian Journal of Criminology 13, no. 3 (July 4, 2019): 395–407. http://dx.doi.org/10.17150/2500-4255.2019.13(3).395-407.
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The authors examine the necessity and relevance of using mathematical models for the digitization of criminal policy while simultaneously taking into account the results of qualitative analysis of the criminogenic situation (theoretical modeling) and using probabilistic prediction models of crime counteraction results (empirical modeling). They determine the chronological matrix of key criminogenic events of modern Russian political and economic history, which forms the basis for developing a mathematical model of predicting changes in the criminal policy. The authors conclude that contemporary criminal policy contains objective signs of manipulative character and that criminal policy decisions cannot be based on it exclusively. It is noted that the presented prediction models based on the theory of relativity allow to make verifiable quantitative evaluations of the situation in counteracting negative socio-legal phenomena and to take into account not only the latent component of these phenomena, but also the differences caused by changes in their criminal law assessment. The presented approach could be used to build a triplex system of official monitoring of criminogenic situation at the federal and regional levels based on the collection, analysis, assessment and prediction of information on criminality from three sources: criminal statistics, public opinion polls’ results, expert polls’ results. According to the authors, the creation of this system is a mandatory prerequisite for the transition from a dominantly repressive model of crime counteraction (typical for most contemporary states) to the preventive model. As the probable effectiveness of preventive model of crime counteraction could be first calculated on the basis of planned expenses and available resources and then compared with the actually achieved effectiveness of such counteraction, the state and the society could gain a considerably more effective instrument of controlling the criminal policy’s quality in comparison with the one used today, which will make it possible to ensure a gradual transition from the high cost criminal policy implemented through trial and error to the digital criminal policy based on the results of preliminary and verified calculations.
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Gaspar, Pedro D., Joel Alves, and Pedro Pinto. "Simplified Approach to Predict Food Safety through the Maximum Specific Bacterial Growth Rate as Function of Extrinsic and Intrinsic Parameters." ChemEngineering 5, no. 2 (May 10, 2021): 22. http://dx.doi.org/10.3390/chemengineering5020022.
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Currently, we assist the emergence of sensors and low-cost information and communication technologies applied to food products, in order to improve food safety and quality along the food chain. Thus, it is relevant to implement predictive mathematical modeling tools in order to predict changes in the food quality and allow decision-making for expiration dates. To perform that, the Baranyi and Roberts model and the online tool Combined Database for Predictive Microbiology (Combase) were used to determine the factors that define the growth of different bacteria. These factors applied to the equation that determines the maximum specific growth rate establish a relation between the bacterial growth and the intrinsic and extrinsic factors that define the bacteria environment. These models may be programmed in low-cost wireless biochemical sensor devices applied to packaging and food supply chains to promote food safety and quality through real time traceability.
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Paulsen, Gene W., and John D. Reid. "Nonlinear Finite-Element Analysis of Dual Support Breakaway Sign." Transportation Research Record: Journal of the Transportation Research Board 1528, no. 1 (January 1996): 146–54. http://dx.doi.org/10.1177/0361198196152800116.
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Breakaway supports are common devices used for dual support signs located along the roadway. Design of these systems often involves several costly vehicle crash tests to ensure their effectiveness. It is believed that mathematical modeling can be used to help develop new sign systems in a more timely and cost-effective manner. To this end, a dual support breakaway sign system was successfully modeled using LS-DYNA3D, a nonlinear, large deformation finite-element package. Small component models were first constructed on critical parts of the breakaway sign system. The component models were compared with physical component tests to aid in the development process, as well as to validate the results. The components were then assembled into a complete system model. Very few changes were made in the complete sign model, because problems were worked out in component modeling. Results from two full-scale vehicle crash tests were used to validate the system model. With successful results, the model can now be used to study various sign modifications and configurations.
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Lohmann, Philipp, Anna-Katharina Meißner, Martin Kocher, Elena K. Bauer, Jan-Michael Werner, Gereon R. Fink, Nadim J. Shah, Karl-Josef Langen, and Norbert Galldiks. "Feature-based PET/MRI radiomics in patients with brain tumors." Neuro-Oncology Advances 2, Supplement_4 (December 1, 2020): iv15—iv21. http://dx.doi.org/10.1093/noajnl/vdaa118.
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Abstract Radiomics allows the extraction of quantitative features from medical images such as CT, MRI, or PET, thereby providing additional, potentially relevant diagnostic information for clinical decision-making. Because the computation of these features is performed highly automated on medical images acquired during routine follow-up, radiomics offers this information at low cost. Further, the radiomics features can be used alone or combined with other clinical or histomolecular parameters to generate predictive or prognostic mathematical models. These models can then be applied for various important diagnostic indications in neuro-oncology, for example, to noninvasively predict relevant biomarkers in glioma patients, to differentiate between treatment-related changes and local brain tumor relapse, or to predict treatment response. In recent years, amino acid PET has become an important diagnostic tool in patients with brain tumors. Therefore, the number of studies in patients with brain tumors investigating the potential of PET radiomics or combined PET/MRI radiomics is steadily increasing. This review summarizes current research regarding feature-based PET as well as combined PET/MRI radiomics in neuro-oncology.
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Maass, Wolfgang, and Eduardo D. Sontag. "Neural Systems as Nonlinear Filters." Neural Computation 12, no. 8 (August 1, 2000): 1743–72. http://dx.doi.org/10.1162/089976600300015123.
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Experimental data show that biological synapses behave quite differently from the symbolic synapses in all common artificial neural network models. Biological synapses are dynamic; their “weight” changes on a short timescale by several hundred percent in dependence of the past input to the synapse. In this article we address the question how this inherent synaptic dynamics (which should not be confused with long term learning) affects the computational power of a neural network. In particular, we analyze computations on temporal and spatiotemporal patterns, and we give a complete mathematical characterization of all filters that can be approximated by feedforward neural networks with dynamic synapses. It turns out that even with just a single hidden layer, such networks can approximate a very rich class of nonlinear filters: all filters that can be characterized by Volterra series. This result is robust with regard to various changes in the model for synaptic dynamics. Our characterization result provides for all nonlinear filters that are approximable by Volterra series a new complexity hierarchy related to the cost of implementing such filters in neural systems.
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Двейрін, Олександр Захарович, Віктор Іванович Рябков, Людмила Валеріївна Капітанова, and Катерина Володимирівна Майорова. "Порівняльна оцінка модифікацій літаків транспортної категорії за частковими та інтегральними показниками ефективності." Aerospace technic and technology, no. 3 (May 27, 2021): 4–12. http://dx.doi.org/10.32620/aktt.2021.3.01.
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The subject of the article is a method for evaluating the effectiveness of modifications of transport category aircraft by partial and integrated indicators, including the marketing cost of the flight and the cost of aircraft hours of air transportation, the amounts of which provide the relationship of economic indicators and parameters used in the design. The aim is to increase the efficiency of modifications of transport category aircraft relative to the basic ones. Objectives: to develop models for estimating modification changes according to integrated cost indicators; to carry out a comparative assessment of different modifications of the transport category aircraft in terms of partial and integrated cost indicators. The methods used are analysis and synthesis of research indicators, mathematical approaches for their evaluation based on the solution of systems of equations. The following results were obtained. According to the analysis and synthesis, the shortcomings of the above partial cost-effectiveness indicators were identified, Optimization of modifications on this indicator gives the maximum economic effect. Taking into account this circumstance, to assess the cost-effectiveness of modifications of transport aircraft, models have been developed that allow determining the cost of LC modifications with a variant change of the modified parameters, such as takeoff mass, flight performance, declared resource, etc., which are laid before modification. making conceptual decisions when creating it. Five modifications of a light transport aircraft are considered, in which such parameters as take-off mass and flight performance were changed. It is accepted that the change in takeoff mass is associated with an increase in the transported cargo, and the change in flight performance - with an increase in range from 2000 to 4000 km. Based on mathematical approaches for estimating existing partial and newly introduced integrated indicators, these five possible modifications of light transport aircraft are analyzed. There is a clear inadequacy in assessing the effectiveness of the developed options for partial and integrated indicators of their effectiveness. Conclusions. The scientific novelty of the obtained results is as follows: a method for estimating the total cost of LC modifications of transport category aircraft, taking into account the characteristic parameters of the modification: flight performance in the form of the characteristic "cargo - range"; the declared resource of modification, and also partial criteria, such as cost of air-hour of air transportation; the cost of transportation of 1 ton of cargo per 1 kilometer; full cost per flight of a transport category aircraft. The proposed method has significantly expanded the information based on which decisions can be made on the competitiveness of various modifications.
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Parada Salado, Juan Gerardo, Carlos Alonso Herrera Ramírez, Allan Giovanni Soriano Sánchez, and Martín Antonio Rodríguez Licea. "Nonlinear Stabilization Controller for the Boost Converter with a Constant Power Load in Both Continuous and Discontinuous Conduction Modes." Micromachines 12, no. 5 (May 6, 2021): 522. http://dx.doi.org/10.3390/mi12050522.
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The operation of Boost converters in discontinuous conduction mode (DCM) is suitable for many applications due to the, among other advantages, inductor volume reduction, high efficiency, paralleling, and low cost. Uses in biomedicine, nano/microelectromechanical, and higher power systems, where wide ranges of input/output voltage and a constant power load (CPL) can coexist, are well-known examples. Under extremely wide operating ranges, it is not difficult to change to a continuous conduction mode (CCM) operation, and instability, chaos, or bifurcations phenomena can occur regardless of the conduction mode. Unfortunately, existing control strategies consider a single conduction mode or linearized models because only slight resistive/CPL power level or input/output voltage variations (and no conduction mode changes) were expected. In this paper, new mathematical models for the Boost converter (with resistive or CPL) that are conduction mode independent are presented and validated. Since the open-loop dynamics of the proposed CPL model is unstable, a nonlinear control law capable of stabilizing the boost converter regardless of the conduction mode is proposed. A stability analysis based on a common-Lyapunov function is provided, and numerical and experimental tests are presented to show the proposal’s effectiveness.
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Sin, V. W. T., and M. Wiercigroch. "A symmetrically piecewise linear oscillator: Design and measurement." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 213, no. 3 (March 1, 1999): 241–49. http://dx.doi.org/10.1243/0954406991522617.
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A simple piecewise linear system with symmetrical flexible constraints was designed and manufactured to carry out a wide range of experimental dynamic analysis and ultimately to validate piecewise models. The design choice was based on the following criteria: accuracy in representing the mathematical model, manufacturing simplicity, flexibility in terms of parameter changes and cost effectiveness. The system consists of a block mass attached to two leaf springs, the stiffness of which can easily be varied by changing their length. The secondary stiffness in the form of cantilever beams can be widely varied in the same way. The clearance between the mass and secondary springs can also be varied by adjusting the screws at the ends of the beams. A variable pneumatic damper is mounted on the upper surface of the mass and provides a means of changing the viscous damping coefficient. The experimental set-up, calibration procedures and typical results are discussed.
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Chai, Ming G., Menino O. Cotta, Mohd H. Abdul-Aziz, and Jason A. Roberts. "What Are the Current Approaches to Optimising Antimicrobial Dosing in the Intensive Care Unit?" Pharmaceutics 12, no. 7 (July 7, 2020): 638. http://dx.doi.org/10.3390/pharmaceutics12070638.
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Antimicrobial dosing in the intensive care unit (ICU) can be problematic due to various challenges including unique physiological changes observed in critically ill patients and the presence of pathogens with reduced susceptibility. These challenges result in reduced likelihood of standard antimicrobial dosing regimens achieving target exposures associated with optimal patient outcomes. Therefore, the aim of this review is to explore the various methods for optimisation of antimicrobial dosing in ICU patients. Dosing nomograms developed from pharmacokinetic/statistical models and therapeutic drug monitoring are commonly used. However, recent advances in mathematical and statistical modelling have resulted in the development of novel dosing software that utilise Bayesian forecasting and/or artificial intelligence. These programs utilise therapeutic drug monitoring results to further personalise antimicrobial therapy based on each patient’s clinical characteristics. Studies quantifying the clinical and cost benefits associated with dosing software are required before widespread use as a point-of-care system can be justified.
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Kwon, Jisoo A., Georgina M. Chambers, Fabio Luciani, Lei Zhang, Shamin Kinathil, Dennis Kim, Hla-Hla Thein, et al. "Hepatitis C treatment strategies in prisons: A cost-effectiveness analysis." PLOS ONE 16, no. 2 (February 11, 2021): e0245896. http://dx.doi.org/10.1371/journal.pone.0245896.
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In Australian prisons approximately 20% of inmates are chronically infected with hepatitis C virus (HCV), providing an important population for targeted treatment and prevention. A dynamic mathematical model of HCV transmission was used to assess the impact of increasing direct-acting antiviral (DAA) treatment uptake on HCV incidence and prevalence in the prisons in New South Wales, Australia, and to assess the cost-effectiveness of alternate treatment strategies. We developed four separate models reflecting different average prison lengths of stay (LOS) of 2, 6, 24, and 36 months. Each model considered four DAA treatment coverage scenarios of 10% (status-quo), 25%, 50%, and 90% over 2016–2045. For each model and scenario, we estimated the lifetime burden of disease, costs and changes in quality-adjusted life years (QALYs) in prison and in the community during 2016–2075. Costs and QALYs were discounted 3.5% annually and adjusted to 2015 Australian dollars. Compared to treating 10% of infected prisoners, increasing DAA coverage to 25%, 50%, and 90% reduced HCV incidence in prisons by 9–33% (2-months LOS), 26–65% (6-months LOS), 37–70% (24-months LOS), and 35–65% (36-months LOS). DAA treatment was highly cost-effective among all LOS models at conservative willingness-to-pay thresholds. DAA therapy became increasingly cost-effective with increasing coverage. Compared to 10% treatment coverage, the incremental cost per QALY ranged from $497-$569 (2-months LOS), -$280–$323 (6-months LOS), -$432–$426 (24-months LOS), and -$245–$477 (36-months LOS). Treating more than 25% of HCV-infected prisoners with DAA therapy is highly cost-effective. This study shows that treating HCV-infected prisoners is highly cost-effective and should be a government priority for the global HCV elimination effort.
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Ghionea, Ionuţ Gabriel, Goran Devedžić, and Saša Ćuković. "Parametric Modeling of Surfaces Using CATIA v5 Environment." Applied Mechanics and Materials 760 (May 2015): 93–98. http://dx.doi.org/10.4028/www.scientific.net/amm.760.93.
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The goal of the CAD parametric modeling is to create a 3D representation, flexible and complex enough to encourage the engineer to easily consider a variety of designs with the cost of applying changes as low as possible. Geometric modeling systems provide a virtual environment similar to the real one in which the physical model is constructed/designed and manipulated. Using such a system, the engineer models, adds, deforms and edits parts in the process of detailing a shape. The virtual model may look the same as the real physical model, but it’s intangible. However, the 3D virtual model is accompanied by its mathematical description, parameters, restraints and these eliminates the need of measurements for prototyping or mass production, can be modified at any modeling phase, can be tested in various ways etc., which is a major disadvantage of using a physical part. This paper presents some theoretical aspects regarding the design process of products including surfaces and a few case studies showing the many possibilities in creating complex surfaces using the CATIA v5 software.
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Bokhove, Onno, Tiffany Hicks, Wout Zweers, and Thomas Kent. "Wetropolis extreme rainfall and flood demonstrator: from mathematical design to outreach." Hydrology and Earth System Sciences 24, no. 5 (May 14, 2020): 2483–503. http://dx.doi.org/10.5194/hess-24-2483-2020.
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Abstract. Government and consulting experts on flood mitigation generally face difficulties when trying to explain the science of extreme flooding to the general public, in particular the concept of a return period. Too often, for example, people perceive they are safe for the next 100 years after a 1:100-year return-period flood has hit their town. UK flood practitioners therefore gave us the challenge to design an outreach tool that conceptualises the science of flooding in a way that is accessible to and directly engages the public, and in particular demonstrates what a return period is. Furthermore, we were tasked with designing a live 3-D physical model rather than a graphical or animated 2-D game on a screen. We show here how we tackled that challenge by designing, constructing, and showcasing the Wetropolis Flood Demonstrator. Wetropolis is a transportable and conceptual physical model with random rainfall, river flow, a flood plain, an upland reservoir, a porous moor, representing the upper catchment and visualising groundwater flow, and a city which can flood following extreme and random rainfall. A key novelty is the supply of rainfall every Wetropolis day. Several aspects of Wetropolis are considered. i. We present the modular mathematical and numerical design on which Wetropolis is based. It guided the choice of parameter values of Wetropolis, which was loosely inspired by the Leeds Boxing Day floods of the River Aire in 2015. The design model further serves as the building block and inspiration for adaptations suited to particular local demands. Moreover, the model is purposely lean and therefore quick to compute, serving flexibility in the outreach-tool design, but is less suitable for any detailed scientific validation.ii. The constructed Wetropolis is described here in broad terms, but we include a link to a GitHub site with details to inspire other bespoke designs. The goal, again, is to facilitate new adaptations of Wetropolis for particular catchments different to the Leeds River Aire case.iii. Our experience in showcasing Wetropolis is summarised and discussed, with the purpose of giving an overview as well as inspiring improved and bespoke adaptations. While Wetropolis should be experienced live, with videos found on the GitHub site, here we provide a photographic overview. To date, Wetropolis has been showcased to 500 to 1000 people at public workshops and exhibitions on recent UK floods, as well as to flood practitioners and scientists at various research and stakeholder workshops.iv. We conclude with some ongoing design changes, including how people can experience natural flood management in a revised Wetropolis design. Finally, we also discuss how Wetropolis, although originally focussed solely on outreach, led to a new cost-effectiveness analysis and protocol for assessing flood-mitigation plans and inspired other physical models for use in education and water management.
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Gomez, Christopher, Deirdre E. Hart, Patrick Wassmer, Imai Kenta, Hiroki Matsui, and Mariko Shimizu. "Coastal Evolution, Geomorphic Processes and Sedimentary Records in the Anthropocene." Forum Geografi 33, no. 1 (August 1, 2019): 1–24. http://dx.doi.org/10.23917/forgeo.v33i1.7551.
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The question of whether or not we agree with the term Anthropocene becomes inconsequential when examining coastal environments. With few exceptions, anthropogenic encroachment on, and reshaping of, the global coastal zone is evident from space via multiple spectral views. Humans have become one of the dominant agents of coastal system change during the latest part of their relatively short existence, and nowhere is the humanization of coastal landscapes more evident than on islands. Using three island nations characterized by different stages and styles of coastal development – New Zealand, Japan, and Indonesia - we investigate the role of anthropogenic activity in coastal evolution, geomorphology and sediment records. Using field investigations, Geographical Information System (GIS) analyses, and mathematical and conceptual models, we reveals how anthropogenic activity influences processes at multiple time and space scales, with enduring effects. Our first anthropogenic impact investigation focusses on the potential effects of sea level rise (SLR) due to anthropogenic climate change. Using the earthquake-induced land-subsidence experienced in Christchurch, New Zealand, as a relative SLR example (‘Laboratory Christchurch’), evidence shows that coastal settlements are likely to be impacted not only at the shore but further inland via coast- connected waterways, where drainage is impeded due to an increase in the base level of that is the sea. Relative SLR makes it more difficult to evacuate water from subaerial and subsurface hydrosystems, and simulations show that future SLR is also likely to temporarily reduce some rivermouth sediment discharges, creating the potential for accelerated erosion in river-coast interface environments. In addition to flow-on effects from waterways, coastlines themselves have been highly affected by human activity over recent decades to centuries. In Tokyo, the shoreline has undergone artificial progradation, in places by more than 2 km, where concrete has supplanted mudflats, often at elevations above the hinterland of reclaimed areas. In addition to changes in Tokyo’s unconsolidated shores, consolidated coastal cliffs have been modified with the removal of natural talus buffers, again increasing the potential for erosion acceleration. Finally, in our third example, studies of the 2004 Indian Ocean tsunami and the 2011 Tohoku tsunami show that anthropogenic activities and structures play an important role in controlling the erosion and depostion of sediments during extreme events. A chronology of tsunami deposits from the Tohoku coast shows that sedimentary records from tsunami events have become thinner in recent centuries, independent of the incident tsunami wave hydrodynamics, and in relation to increasing levels of coastal plain, shoreline and nearshore development. In light of these multi-scale and multi-process effects, we argue that the Anthropocene is clearly distinguishable from the Holocene in coastal environments due to the significantly stronger signatures of human influence that characterise the former time period.
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Eggermont, J. J. "Mathematical Models for Developmental Changes." Acta Oto-Laryngologica 99, sup421 (January 1985): 102–7. http://dx.doi.org/10.3109/00016488509121763.
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Ershad, Abdul Latif, Ali Rajabi-Siahboomi, Shahrzad Missaghi, Daniel Kirby, and Afzal Rahman Mohammed. "Multi-Analytical Framework to Assess the In Vitro Swallowability of Solid Oral Dosage Forms Targeting Patient Acceptability and Adherence." Pharmaceutics 13, no. 3 (March 19, 2021): 411. http://dx.doi.org/10.3390/pharmaceutics13030411.
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A lack of effective intervention in addressing patient non-adherence and the acceptability of solid oral dosage forms combined with the clinical consequences of swallowing problems in an ageing world population highlight the need for developing methods to study the swallowability of tablets. Due to the absence of suitable techniques, this study developed various in vitro analytical tools to assess physical properties governing the swallowing process of tablets by mimicking static and dynamic stages of time-independent oral transitioning events. Non-anatomical models with oral mucosa-mimicking surfaces were developed to assess the swallowability of tablets; an SLA 3D printed in vitro oral apparatus derived the coefficient of sliding friction and a friction sledge for a modified tensometer measured the shear adhesion profile. Film coat hydration and in vitro wettability was evaluated using a high-speed recording camera that provided quantitative measurements of micro-thickness changes, simulating static in vivo tablet–mucosa oral processing stages with artificial saliva. In order to ascertain the discriminatory power and validate the multianalytical framework, a range of commonly available tablet coating solutions and new compositions developed in our lab were comparatively evaluated according to a quantitative swallowability index that describes the mathematical relationship between the critical physical forces governing swallowability. This study showed that the absence of a film coat significantly impeded the ease of tablet gliding properties and formed chalky residues caused by immediate tablet surface erosion. Novel gelatin- and λ-carrageenan-based film coats exhibited an enhanced lubricity, lesser resistance to tangential motion, and reduced stickiness than polyvinyl alcohol (PVA)–PEG graft copolymer, hydroxypropyl methylcellulose (HPMC), and PVA-coated tablets; however, Opadry® EZ possessed the lowest friction–adhesion profile at 1.53 a.u., with the lowest work of adhesion profile at 1.28 J/mm2. For the first time, the in vitro analytical framework in this study provides a fast, cost-effective, and repeatable swallowability ranking method to screen the in vitro swallowability of solid oral medicines in an effort to aid formulators and the pharmaceutical industry to develop easy-to-swallow formulations.
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Servare Junior, Marcos Wagner Jesus, Helder Roberto de Oliveira Rocha, José Leandro Félix Salles, and Sylvain Perron. "A Linear Relaxation-Based Heuristic for Iron Ore Stockyard Energy Planning." Energies 13, no. 19 (October 8, 2020): 5232. http://dx.doi.org/10.3390/en13195232.
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Planning the use of electrical energy in a bulk stockyard is a strategic issue due to its impact on efficiency and responsiveness of these systems. Empirical planning becomes more complex when the energy cost changes over time. The mathematical models currently studied in the literature consider many actors involved, such as equipment, sources, blends, and flows. Each paper presents different combinations of actors, creating their own transportation flows, thus increasing the complexity of this problem. In this work, we propose a new mixed integer linear programming (MILP) model for stockyard planning solved by a linear relaxation-based heuristic (LRBH) to minimize the plan’s energy cost. The proposed algorithm will allow the planner to find a solution that saves energy costs with an efficient process. The numerical results show a comparison between the exact and heuristic solutions for some different instances sizes. The linear relaxation approach can provide feasible solutions with a 3.99% average distance of the objective function in relation to the optimal solution (GAP) in the tested instances and with an affordable computation time in instances where the MILP was not able to provide a solution. The model is feasible for small and medium-sized instances, and the heuristic proposes a solution to larger problems to aid in management decision making.
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Maghool, Samira, and Nahid Maleki-Jirsaraei. "Epidemic spreading phenomena on a scale-free network with time-varying transmission rate due to social responses." International Journal of Modern Physics C 31, no. 10 (September 13, 2020): 2050148. http://dx.doi.org/10.1142/s012918312050148x.
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In this paper, we study and simulate the effect of individual social responses, as a collective factor, on the epidemic spreading processes. We formally define the problem based on the traditional [Formula: see text] and [Formula: see text] compartmental models considering the time-varying infection probability dependent on the social responses. In this study, models of generic and special case scenarios are developed. While in the generic case the effective parameter of behavioral response is demonstrated as one collective factor, in the special case the behavioral response is assumed as the combination of two collective factors: social cost and transfer rate of social awareness. With social cost, we refer to the costs incurred by a certain population to prevent or mitigate an epidemic. With transfer rate of social awareness, we describe the averaged rate of received information and knowledge regarding a disease that individuals hold and make use to avoid negative consequences. We show that, while in both [Formula: see text] and [Formula: see text] models the density of infected agents grows exponentially during the initial time steps, the inclusion of our models of social responses, either generic or special one, leads to mitigation of the spreading. As a result of both generic and special cases, the density of infected agents in the stationary state and the maximum number of infected agents decrease according to power-law functions for different values of collective factors. In the special case results, we also witnessed significant changes in the slope of decreasing trends of stationary density of states happening for a critical value of transfer rate of social awareness, approximately at about the inverse of the time interval of transmission rate update. With this result, we point out that increasing the transfer rate of social awareness to about this critical point outperforms any slight increase in social cost in reducing the number of infected agents.
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Ledukhovsky, G. V., S. D. Gorshenin, E. V. Zinovyeva, and A. S. Zinovyeva. "Analysis of efficiency of feed pump control by changing rotation of rotor for power plants of various types." Vestnik IGEU, no. 4 (August 31, 2021): 5–14. http://dx.doi.org/10.17588/2072-2672.2021.4.005-014.
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The type of power plant feed pump drive is selected in the course of a feasibility study. Domestic experience is based on recommendations that have been obtained in the middle of the last century when fuel was relatively cheap. These recommendations are currently being revised. Manufacturers of technological tools of pumps frequency control offer to install fluid couplings, variable frequency electric drives or drive turbines for power plants of various types. At the same time, they declare the high efficiency of such solutions. But the effect is often calculated based on energy savings indicators for the pump drive without considering changes of the operating modes of other equipment of the power plant. An urgent task is a comprehensive assessment of the effectiveness of the measures under consideration. This assessment should consider the objective parameters and modes of facilities operation, as well as interrelation of power electricity cost for own needs and loads of the basic equipment. To determine the technical effect of application of various methods of frequency control of feed pumps, models are used that are developed on the individual basis for each power plant based on the energy characteristics of the equipment. These models include algorithms for heat and electrical balances. Operational characteristics of the feed pumps and performance assessment are calculated according to the known techniques. Based on a unified methodological approach, the authors have developed mathematical models of condensing power supply units and combined heat and power plants for an initial pressure of 12,8 MPa. These models make it possible to determine the effect of frequency control of feed pumps based on data for real time in operation considering the interrelation of power electricity cost for own needs and loads of the basic equipment. Calculation of index of performance of application of various means of frequency control of feed pump performance have been carried out. It is revealed that to assess the efficiency of application of technological tools of frequency control of feed pumps, it is of decisive importance to consider the experience of equipment load, load schedules, the interrelation of power electricity cost for own needs and loads of the basic equipment. No general recommendations to use certain methods of feed pumps control are applicable, when conducting such an assessment.
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Podryadchikova, Ekaterina D., Larisa N. Gilyova, and Alexey V. Dubrovsky. "THE CALCULATION OF THE RANGES OF THE SPECIFIC RATE OF CADASTRAL COST TO BUILD 3D MAPS OF ESTIMATED ZONING (ON THE EXAMPLE OF TYUMEN CITY)." Vestnik SSUGT (Siberian State University of Geosystems and Technologies) 26, no. 3 (2021): 147–61. http://dx.doi.org/10.33764/2411-1759-2021-26-3-147-161.
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The article proposes a method of constructing an interval variation series with equal intervals as a mathematical tool for calculating the step of changes in the UPCS for the maps of estimated zoning. It describes the sequence of calculations, which includes 3 stages: the formation of the interval variation series, the calculation of the distribution center indicators, and the calculation of the relative variation indicators of the interval variation series. The resulting interval variation series allowed us to group the totality of the state cadastral assessment data and present them in the form of homogeneous intervals necessary for performing the estimated zoning. To visualize the results, it is proposed to use a three-dimensional geoinformation model in the form of a 3D prism map, which allows you to visually dis-play changes in the value of the UPC. The presented methodology was tested during the evaluation zoning of the territory of the city of Tyumen using the results of the state cadastral assessment. The created assessment zoning map can be used for cadastral valuation of newly formed real estate ob-jects, for information support of the territorial planning system, as well as for analytical support of in-vestment programs and projects for the development of land and property complexes. Assessment zoning maps made with the use of modern geoinformation technologies in the form of three-dimensional digital models can be one of the elements of an intelligent model of an urban area, which will allow not only to carry out operational management, but also to develop effective mechanisms that optimize the trajectory of spatial development of a locality.
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Mirinejad, Hossein, Paramsothy Jayakumar, and Tulga Ersal. "Modeling Human Steering Behavior During Path Following in Teleoperation of Unmanned Ground Vehicles." Human Factors: The Journal of the Human Factors and Ergonomics Society 60, no. 5 (April 17, 2018): 669–84. http://dx.doi.org/10.1177/0018720818769260.
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Objective: This paper presents a behavioral model representing the human steering performance in teleoperated unmanned ground vehicles (UGVs). Background: Human steering performance in teleoperation is considerably different from the performance in regular onboard driving situations due to significant communication delays in teleoperation systems and limited information human teleoperators receive from the vehicle sensory system. Mathematical models capturing the teleoperation performance are a key to making the development and evaluation of teleoperated UGV technologies fully simulation based and thus more rapid and cost-effective. However, driver models developed for the typical onboard driving case do not readily address this need. Method: To fill the gap, this paper adopts a cognitive model that was originally developed for a typical highway driving scenario and develops a tuning strategy that adjusts the model parameters in the absence of human data to reflect the effect of various latencies and UGV speeds on driver performance in a teleoperated path-following task. Results: Based on data collected from a human subject test study, it is shown that the tuned model can predict both the trend of changes in driver performance for different driving conditions and the best steering performance of human subjects in all driving conditions considered. Conclusions: The proposed model with the tuning strategy has a satisfactory performance in predicting human steering behavior in the task of teleoperated path following of UGVs. Application: The established model is a suited candidate to be used in place of human drivers for simulation-based studies of UGV mobility in teleoperation systems.
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bin Ibrahim, Mohamad Faizul, Ovinis Mark, and Kamarudin bin Shehabuddeen. "An Underwater Glider for Subsea Intervention: A Technical Feasibility Study." Applied Mechanics and Materials 393 (September 2013): 561–66. http://dx.doi.org/10.4028/www.scientific.net/amm.393.561.
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An underwater glider is a type of autonomous underwater vehicle that moves based on small changes in its buoyancy, maneuvering using it wings as it glides through the water. These gliders, currently used in oceanographic sampling, may potentially be used to deliver payloads for subsea intervention at a lower net transport economy (NTE). Net transport economy, is a measure of the cost of transport in terms of the energy consumed per meter traveled, for each kilogram of loaded mass in air or net buoyancy underwater. The current method of payload delivery is either by using customized support vessel or remotely operated vehicle. This paper presents a technical feasibility study of extending the use of these gliders for subsea intervention, with emphasis on payload delivery. Important aspects of an underwater glider such as its volume (size), speed, wing area, wing span, operational depth and net transport economy were considered. The analysis was based on mathematical models governing existing gliders such as legacy gliders and the XRAY Liberdade. The results obtained were validated by extrapolating the present state of the art in underwater gliders to the proposed future use of these gliders, which is for payload delivery. In conclusion, the use of underwater gliders for subsea intervention is feasible based on factors considered in this study.
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Di, Sihao, and Aidong Yang. "Analysis of productivity and stability of synthetic microbial communities." Journal of The Royal Society Interface 16, no. 150 (January 2019): 20180859. http://dx.doi.org/10.1098/rsif.2018.0859.
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Bioreactors that employ a synthetic microbial community hold potential to overcome limitations of those based on a single species, which embrace a higher level of complexity due to the inter-species interactions. In this work, a number of generic system structures involving two cross-feeding species and various types of inhibition have been studied, together with two three-species cases where a third species is introduced to fulfil a specific function. These cases are represented by mathematical models and inspected through bifurcation analysis and numerical simulation to reveal how the system structure and parametrization affect stability and productivity of the bioreactor. The results show that inhibitions generally lead to reduction in both productivity and stability, and that the presence of a negative feedback loop and a positive feedback loop may give rise to oscillation and bi-stability, respectively, depending on the strength of the inhibitions involved. The intended gains by the introduction of a third species may be achieved when its negative side-effect is sufficiently moderate, and at the cost of reduced stability. As observed in several cases, the changes in stability and productivity do not always follow the same trend, implying trade-off between the two objectives in the engineering of such bioreactors.
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Kondoh, Michio. "Anti-predator defence and the complexity–stability relationship of food webs." Proceedings of the Royal Society B: Biological Sciences 274, no. 1618 (April 24, 2007): 1617–24. http://dx.doi.org/10.1098/rspb.2007.0335.
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The mechanism for maintaining complex food webs has been a central issue in ecology because theory often predicts that complexity (higher the species richness, more the interactions) destabilizes food webs. Although it has been proposed that prey anti-predator defence may affect the stability of prey–predator dynamics, such studies assumed a limited and relatively simpler variation in the food-web structure. Here, using mathematical models, I report that food-web flexibility arising from prey anti-predator defence enhances community-level stability (community persistence and robustness) in more complex systems and even changes the complexity–stability relationship. The model analysis shows that adaptive predator-specific defence enhances community-level stability under a wide range of food-web complexity levels and topologies, while generalized defence does not. Furthermore, while increasing food-web complexity has minor or negative effects on community-level stability in the absence of defence adaptation, or in the presence of generalized defence, in the presence of predator-specific defence, the connectance–stability relationship may become unimodal. Increasing species richness, in contrast, always lowers community-level stability. The emergence of a positive connectance–stability relationship however necessitates food-web compartmentalization, high defence efficiency and low defence cost, suggesting that it only occurs under a restricted condition.
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Martynov, V., O. Martynova, S. Makarova, and O. Vietokh. "METHOD FOR CALCULATING THE COMPOSITION OF CELLULAR CONCRETE." Bulletin of Odessa State Academy of Civil Engineering and Architecture, no. 83 (June 4, 2021): 77–85. http://dx.doi.org/10.31650/2415-377x-2021-83-77-85.
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The analysis of existing methods for calculating concrete compositions was carried out. The characteristics and sequence of the calculation-experimental and experimental-calculation methods for the selection of concrete compositions are provided. The advantages and disadvantages of each of the methods are described. These methods are generalized by the general systemic cycle PDCA (Deming cycle), which is determined by the sequence of actions: P (plan) ‒ D (do) ‒ C (check) ‒ A (Action). It was established that for calculating the compositions of the cellular method there is no universal method, which would ensure the achievement of the required strength and average density at the same time. Based on the above, the aim of the thesis was formulated. The aim of the thesis is to develop a method for calculating the composition of cellular concrete, based on experimental-statistical models, which would ensure the production of concrete with the required properties while minimizing the cost of raw materials. A calculation algorithm, a block diagram and a computer program for designing cellular concrete compositions based on experimental-statistical modeling were developed. Using the example of the specified block diagram for calculating concrete compositions, the sequence of calculations is described in detail. The essence of the calculations is that the three-factor mathematical model of the property parameter of cellular concrete, which is supposed to be guaranteed, leads to a second order equation. After that, the roots of the equation are determined. They are substituted into a mathematical model and the composition of concrete is determined in natural values of variable factors. After that, the cost of the composition is determined, which is entered into the data array. Then one of the factors changes, according to the set step and the cycle repeats. At the last stage, the formed data array is processed and the composition with the minimum cost of materials is determined. Testing of the developed software was carried out by processing and calculating a three factor experiment. As a result, the composition of cellular concrete which provides the required strength of foam concrete with a minimum cost of materials, was determined.
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Zapototska, V., and O. Skliarov. "PROSPECTS` ESTIMATION OF RENEWABLE ENERGY POWER OF THE NORTHERN BLACK SEA REGION." Bulletin of Taras Shevchenko National University of Kyiv. Geography, no. 74 (2019): 36–41. http://dx.doi.org/10.17721/1728-2721.2019.74.7.
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The features of the location and functioning of renewable energy sources in the Northern Black Sea region in the context of political and economic transformations are considered. The strategic importance and expediency of using alternative energy power with the use of a “green” tariff and the implementation of a new electricity market have been proved. Analyzed the main factors of development and operation of renewable energy sources, among ecology-geographical, socio-geographical, economic and geopolitical. The ecology-geographical factor makes assess first of all the natural and ecological conditions on the territory, which can be used to create new renewable energy power complexes with huge economic efficiency. For the Ukrainian Black Sea region, the prospects for the development of renewable energy power are primarily related to the use of wind, solar, biomass and geothermal energy. The Northern Black Sea that is part of Ukraine, which receives the largest amount of solar radiation and has a lower relief, which facilitates the movement of winds from the coast of the Black and Azov seas deeper into the territory. In the system of socio-geographical factors, the population density, the pattern of settlements, the level of infrastructure development, the availability of skilled labour forces and the availability of energy consumers will be estimated. An economic factor has allowed evaluating and analyzing the cost of electricity generation from renewable energy power. The assessment of the geopolitical factor enabled the possibility and prospects of cooperation with investors from Norway, Germany, Austria and the Czech Republic. Taking into account advanced international experience in the study of renewable energy capacity. Improved scientific methods for the investigation of renewable energy sources from the standpoint of social geography, not just within technological, engineering and economic areas. The principles of localization of alternative energy power are highlighted, which take into account the socio-geographical features of the Northern Black Sea Region: spatial distribution, labour resource potential, production infrastructure, economic attractiveness, regional competitiveness, etc. Identified functional and sectorial types of the regions of the Northern Black Sea region, which depending on the prevailing types of generation and the volume of production of electric energy. According to the results of the research, four functional-branch types have been identified: solar power – Odesa Region, wind – Donetsk, wind and solar – Kherson and Zaporizhzhia and wind and solar + small hydropower + bioenergy – Mykolaiv Region. By 2026, we predicted changes of those types for the following: wind – Donetsk (without changes), solar + wind – Kherson, Zaporizhzhia (without changes) and Odessa regions and wind + solar + small hydropower + bioenergy – Mykolaiv Region (without changes).Reflected energy- deficient and energy-surplus areas within the Northern Black Sea region, taking into account the balance of renewable energy power and total electricity generation. Investigated the potential of using alternative energy power using three-dimensional mathematical models. Spatial analysis of the most favourable spaces and areas for the development of new capacities of renewable energy power, taking into account the above factors and determinants, has been carried out. The further development of renewable energy power was adjusted according to the United Energy Network Development Plan until 2026 and the flow of foreign direct investment from the countries of the European Union. Presented trend in the dynamics of the distribution of renewable energy power.
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Sajid, Noor, Thomas Parr, Thomas M. Hope, Cathy J. Price, and Karl J. Friston. "Degeneracy and Redundancy in Active Inference." Cerebral Cortex 30, no. 11 (June 3, 2020): 5750–66. http://dx.doi.org/10.1093/cercor/bhaa148.
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Abstract The notions of degeneracy and redundancy are important constructs in many areas, ranging from genomics through to network science. Degeneracy finds a powerful role in neuroscience, explaining key aspects of distributed processing and structure–function relationships in the brain. For example, degeneracy accounts for the superadditive effect of lesions on functional deficits in terms of a “many-to-one” structure–function mapping. In this paper, we offer a principled account of degeneracy and redundancy, when function is operationalized in terms of active inference, namely, a formulation of perception and action as belief updating under generative models of the world. In brief, “degeneracy” is quantified by the “entropy” of posterior beliefs about the causes of sensations, while “redundancy” is the “complexity” cost incurred by forming those beliefs. From this perspective, degeneracy and redundancy are complementary: Active inference tries to minimize redundancy while maintaining degeneracy. This formulation is substantiated using statistical and mathematical notions of degenerate mappings and statistical efficiency. We then illustrate changes in degeneracy and redundancy during the learning of a word repetition task. Finally, we characterize the effects of lesions—to intrinsic and extrinsic connections—using in silico disconnections. These numerical analyses highlight the fundamental difference between degeneracy and redundancy—and how they score distinct imperatives for perceptual inference and structure learning that are relevant to synthetic and biological intelligence.
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Budzier, H., and G. Gerlach. "Calibration of uncooled thermal infrared cameras." Journal of Sensors and Sensor Systems 4, no. 1 (June 2, 2015): 187–97. http://dx.doi.org/10.5194/jsss-4-187-2015.
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Abstract. The calibration of uncooled thermal infrared (IR) cameras to absolute temperature measurement is a time-consuming, complicated process that significantly influences the cost of an IR camera. Temperature-measuring IR cameras display a temperature value for each pixel in the thermal image. Calibration is used to calculate a temperature-proportional output signal (IR or thermal image) from the measurement signal (raw image) taking into account all technical and physical properties of the IR camera. The paper will discuss the mathematical and physical principles of calibration, which are based on radiometric camera models. The individual stages of calibration will be presented. After start-up of the IR camera, the non-uniformity of the pixels is first corrected. This is done with a simple two-point correction. If the microbolometer array is not temperature-stabilized, then, in the next step the temperature dependence of the sensor parameters must be corrected. Ambient temperature changes are compensated for by the shutter correction. The final stage involves radiometric calibration, which establishes the relationship between pixel signal and target object temperature. Not all pixels of a microbolometer array are functional. There are also a number of defective, so-called "dead" pixels. The discovery of defective pixels is a multistep process that is carried out after each stage of the calibration process.
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Zhai, Chi, Qinjun Liu, Jose A. Romagnoli, and Wei Sun. "Modeling/Simulation of the Dividing Wall Column by Using the Rigorous Model." Processes 7, no. 1 (January 8, 2019): 26. http://dx.doi.org/10.3390/pr7010026.
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Dividing wall column (DWC) is an atypical distillation column with an internal, vertical WE partition wall that effectively accommodates two conventional distillation columns into one to improve the thermodynamic efficiency. In previous studies, different equivalent models by combining conventional columns are adopted to approximate the DWC modeling, which may not well describe the integration of the DWC; moreover, the computational cost increases when multiple columns are implemented to represent one DWC. In this paper, a rigorous mathematical model is proposed based on the mass balance, the energy and phase equilibrium of the DWC, where decision variables and state variables are equally treated. The model was developed in the general process modeling system (gPROMS). Based on the rigorous model, the influences of liquid split ratio and vapor split ratio are discussed, and it is shown that the heat duty is sensitive to changes on the liquid and vapor split ratio. Inappropriate liquid and vapor split ratio will increase the mixing effects at both ends of the dividing wall, and adversely affect the thermodynamic efficiency. Hence, the degree of mixing is defined to characterize the column efficiency. Furthermore, the middle component split ratio at the top of the pre-fractionator has an optimal point for better energy saving with certain liquid and vapor split ratios, and can be used as an indicator for the energy performance. Finally, the model was tested and validated against literature data by using the ternary benzene–toluene–xylene mixture system as a case study.
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Hertati, Lesi, and Otniel Safkaur. "PENGARUH SISTEM INFORMASI MANAJEMEN LINGKUNGAN TERHADAP GOOD GOVERMENT GOVERNANCE." Jurnal Ilmu Keuangan dan Perbankan (JIKA) 10, no. 1 (December 23, 2020): 39–64. http://dx.doi.org/10.34010/jika.v10i1.3003.
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An Environmental Management Information System is an information system that produces outputs using inputs that can process all the information needed to meet the organization's objectives for management activities. A good Environmental Management Information System is able to balance the costs and benefits to be gained, meaning an environmental management information system that will save costs, increase revenue that arises from very useful information. The organization must realize that meticulous technology can design and implement an environmental management information system to suit its desires in determining cost limits from the point of benefit to be obtained, then the resulting Environmental Management Information System will provide benefits and money. Integrated and flexible information technology is an environmental management information system tool, in information processing in order to design an environmental management information system that is able to serve the main task. The purpose of the environmental management information system is to meet the general information needs of all managers in the company or within the organizational subunits of the company. The environmental management information system provides users with information in the form of reports and outputs from various mathematical simulation models. The results of this study indicate that the environmental management information system can provide good or bad changes in Good Government Governance that are managed by the company. This research was conducted at PT Bukit Asam Indonesia located in South Sumatra.
Keywords: Environmental Management Information System, Good Government Governance
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Burchardt, Ansgar, Christian Abicht, and Oliver Sander. "An efficient and robust simulator for wear of total knee replacements." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 234, no. 9 (June 24, 2020): 921–30. http://dx.doi.org/10.1177/0954411920933022.
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Wear on total knee replacements is an important criterion for their performance characteristics. Numerical simulations of such wear have seen increasing attention over the last years. They have the potential to be much faster and less expensive than the in vitro tests in use today. While it is unlikely that in silico tests will replace actual physical tests in the foreseeable future, a judicious combination of both approaches can help making both implant design and pre-clinical testing quicker and more cost-effective. The challenge today for the design of simulation methods is to obtain results that convey quantitative information and to do so quickly and reliably. This involves the choice of mathematical models as well as the numerical tools used to solve them. The correctness of the choice can only be validated by comparing with experimental results. In this article, we present finite element simulations of the wear in total knee replacements during the gait cycle standardized in the ISO 14243-1 document, used for compliance testing in several countries. As the ISO 14243-1 standard is precisely defined and publicly available, it can serve as an excellent benchmark for comparison of wear simulation methods. We use comparatively simple wear and material models, but we solve them using a new wear algorithm that combines extrapolation of the geometry changes with a contact algorithm based on nonsmooth multigrid ideas. The contact algorithm works without Lagrange multipliers and penalty parameters, achieving unparalleled stability and efficiency. We compare our simulation results with the experimental data from physical tests using two different actual total knee replacements. Even though the model is simple, we can predict the total mass loss due to wear after 5-million gait cycles, and we observe a good match between the wear patterns seen in experiments and our simulation results. When compared with a state-of-the-art penalty-based solver for the same model, we measure a roughly fivefold increase of execution speed.
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Tvaronavičienė, Manuela, Evgeny Lisin, and Vladimir Kindra. "Power Market Formation for Clean Energy Production as the Prerequisite for the Country’s Energy Security." Energies 13, no. 18 (September 20, 2020): 4930. http://dx.doi.org/10.3390/en13184930.
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The paper analyzes the main issues of power market development for clean energy production within the broader framework of ensuring the country’s energy security. In addition, special attention is paid to the technologies aimed at reducing emissions of toxic substances and greenhouse gases by the fossil-fired power plants. Even though the future electricity markets would most likely depend on the high shares of renewable energy sources (RES) in the electricity system, energy efficiency such as the one based on the near-zero emission technologies might also play a crucial role in the transition to the carbon-free energy future. In particular, there are the oxy-fuel combustion technologies that might help to reduce the proportion of unburned fuel and increase the efficiency of the power plant while reducing the emissions of flue gases. Our paper focuses on the role and the place of the near-zero emission technologies in the production of clean energy. We applied economic and mathematical models for assessing the prospects for applying oxy-fuel combustion technology in thermal power plants, taking into account the system of emission quotas and changes in the fuel cost. Our results demonstrate that at the current fuel prices, it is advisable to use economical combined cycle gas turbines (CCGT). At the same time, when quotas for greenhouse gas emissions are introduced and fuel costs increase by 1.3 times, it becomes economically feasible to use the oxy-fuel combustion technology which possesses significant economic advantages over CCGT with respect to the capture and storage of greenhouse gases.
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Cunha, Daniel de Noronha Figueiredo Vieira da, José Carlos Pereira, Oriel Fajardo de Campos, José Luis Braga, Fabyano Fonseca e. Silva, and Janaina Azevedo Martuscello. "Evaluation of a dynamic simulation model for milk production systems." Revista Brasileira de Zootecnia 39, no. 4 (April 2010): 903–12. http://dx.doi.org/10.1590/s1516-35982010000400027.
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The objective of this study was to develop and to evaluate a dynamic simulation model, with stochastic components in order to assess milk production systems. The simulation model was developed by using STELLA 9.0, ZooCalc 1.0 and electronic data sheets. The physical structure of the herd was divided into 15 interlinked modules that represented categories or subdivisions of categories. Mathematical models obtained from the literature were used to simulate the body weight of growing and lactating animals and milk production and milk composition. Electronic data sheets were used to calculate the nutritional requirements and dietary balance. After cost minimization, each feed was evaluated by using ZooCalc 1.0. Some average responses of farm size, zootechnical and economic index, the change in the area used for com silage production, the calving interval and age at first insemination were obtained to evaluate whether the simulation model was working consistently with the expected. To assess the capacity of the model to gene rate simulated values that approach reality, the degree of linear association was measured between the values generated by the model and the values observed in practice. Sensitivity analyses showed that the values produced by the simulation model were in agreement with the expected results, in response to changes in the area of com crop used for com silage production, the calving interval and the age at first insemination. There was correlation between the values generated by the simulation model and the values observed in practice and the degree of linear association for the variables could be considered high.
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Kosowski, Piotr, and Katarzyna Kosowska. "Valuation of Energy Security for Natural Gas—European Example." Energies 14, no. 9 (May 7, 2021): 2678. http://dx.doi.org/10.3390/en14092678.
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Recently there has been an ongoing discussion about energy security. This has been caused by tensions affecting international relations, and the emergence of new geopolitical threats. As one of the main sources of primary energy, natural gas is an obvious subject of interest in this discussion. In Europe, the natural gas market is rapidly evolving, which has resulted in a lack of clarity regarding who is responsible for the security of the gas supply. It is not clear now how to measure the security of the gas supply in economic estimates and by whom that security should be financed. In this paper, the authors present an approach which can be used for valuation of energy security concerning the security of natural gas storage using stochastic modelling based on the mathematical model of the “Newsvendor problem”. The valuation is made from the point of view of countries and considers their individual attitudes to the risk of disruption of deliveries, which is a novel approach to the problem. The authors believe that the current level of storage capacities, as compared to the demand for natural gas, can show the attitude of each country to the risk and potential cost of stockout. In line with this belief, the target value in the model is not the optimal level of inventory, but the cost of stockout. The results show significant variations in the assessment of the risk. The future of natural gas as an important fuel and source of primary energy in Europe is not clear and unfavorable changes have been sped up by the COVID-19 pandemic. Gas (energy) companies in Europe are turning to decarbonization and green energy, and the pandemic has accelerated these changes. European energy companies used to see the use of natural gas as a transition fuel and a key component of their long-term decarbonization strategies, but now they are switching to multi-energy models through massive investments in renewables and hydrogen. Experts expect that gas will remain an important part of Europe’s energy supply, but it may be gradually replaced by hydrogen and renewables.
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Mosselman, Erik. "A review of mathematical models of river planform changes." Earth Surface Processes and Landforms 20, no. 7 (November 1995): 661–70. http://dx.doi.org/10.1002/esp.3290200708.
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