Journal articles: 'El Niño current Mathematical models'

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Kotyan, Shashank, and Danilo Vasconcellos Vargas. "Adversarial robustness assessment: Why in evaluation both L0 and L∞ attacks are necessary." PLOS ONE 17, no. 4 (April 14, 2022): e0265723. http://dx.doi.org/10.1371/journal.pone.0265723.

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There are different types of adversarial attacks and defences for machine learning algorithms which makes assessing the robustness of an algorithm a daunting task. Moreover, there is an intrinsic bias in these adversarial attacks and defences to make matters worse. Here, we organise the problems faced: a) Model Dependence, b) Insufficient Evaluation, c) False Adversarial Samples, and d) Perturbation Dependent Results. Based on this, we propose a model agnostic adversarial robustness assessment method based on L0 and L∞ distance-based norms and the concept of robustness levels to tackle the problems. We validate our robustness assessment on several neural network architectures (WideResNet, ResNet, AllConv, DenseNet, NIN, LeNet and CapsNet) and adversarial defences for image classification problem. The proposed robustness assessment reveals that the robustness may vary significantly depending on the metric used (i.e., L0 or L∞). Hence, the duality should be taken into account for a correct evaluation. Moreover, a mathematical derivation and a counter-example suggest that L1 and L2 metrics alone are not sufficient to avoid spurious adversarial samples. Interestingly, the threshold attack of the proposed assessment is a novel L∞ black-box adversarial method which requires even more minor perturbation than the One-Pixel Attack (only 12% of One-Pixel Attack’s amount of perturbation) to achieve similar results. We further show that all current networks and defences are vulnerable at all levels of robustness, suggesting that current networks and defences are only effective against a few attacks keeping the models vulnerable to different types of attacks.

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Zhao, Guangwen, Shuzhen Duan, Qiuzhan Tian, and Tan Wu. "Mathematical models of current losses in bipolar cells." Metallurgical Transactions B 21, no. 4 (August 1990): 783–90. http://dx.doi.org/10.1007/bf02654257.

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Gavaghan, David, Alan Garny, Philip K. Maini, and Peter Kohl. "Mathematical models in physiology." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1842 (March 22, 2006): 1099–106. http://dx.doi.org/10.1098/rsta.2006.1757.

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Computational modelling of biological processes and systems has witnessed a remarkable development in recent years. The search-term ( modelling OR modeling ) yields over 58 000 entries in PubMed, with more than 34 000 since the year 2000: thus, almost two-thirds of papers appeared in the last 5–6 years, compared to only about one-third in the preceding 5–6 decades. The development is fuelled both by the continuously improving tools and techniques available for bio-mathematical modelling and by the increasing demand in quantitative assessment of element inter-relations in complex biological systems. This has given rise to a worldwide public domain effort to build a computational framework that provides a comprehensive theoretical representation of integrated biological function—the Physiome. The current and next issues of this journal are devoted to a small sub-set of this initiative and address biocomputation and modelling in physiology, illustrating the breadth and depth of experimental data-based model development in biological research from sub-cellular events to whole organ simulations.

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Amirov, Sultan Faizullaevich, and Nargisa Kamilovna Babanazarova. "Mathematical models of the new remote transformer current transducers." IOP Conference Series: Earth and Environmental Science 808, no. 1 (July 1, 2021): 012001. http://dx.doi.org/10.1088/1755-1315/808/1/012001.

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Lachin, Viatcheslav. "Comparative analysis of mathematical models for approximation of current absorption." University News. North-Caucasian Region. Technical Sciences Series, no. 2 (June 2015): 14–18. http://dx.doi.org/10.17213/0321-2653-2015-2-14-18.

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Tziouvaras, D. A., P. McLaren, G. Alexander, D. Dawson, J. Esztergalyos, C. Fromen, M. Glinkowski, et al. "Mathematical models for current, voltage, and coupling capacitor voltage transformers." IEEE Transactions on Power Delivery 15, no. 1 (2000): 62–72. http://dx.doi.org/10.1109/61.847230.

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Stentsel, Y., O. Porkuian, K. Litvinov, and T. Sotnikova. "Mathematical Models of Additional Measurement Errors of Control Means." Metrology and instruments, no. 2 (May 3, 2019): 43–51. http://dx.doi.org/10.33955/2307-2180(2)2019.43-51.

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Studies have shown that under industrial conditions there is rarely a correction of the current measurement result when the influencing parameter deviates from the normalized value. The existing method of determining the additional measurement error is that in order to obtain the real value of the measurement result, the correction is calculated, which leads to the current value of indexes of control means. The correction value is determined by dividing the degree of the influencing parameter deviation by the normalized value of the additional error. This method of determining the correction is not accurate enough, since it does not take into account the nonlinear dependence of the additional measurement error on the change in the influencing parameter, as well as on the current value of the output signal of control means. To determine the real value of the measured parameter and the additional error, the method of integral-type functional is proposed. The essence of the method is in determining the difference of planes under the nominal and current parts of the static characteristic, limited by the measurement range. It is shown that the planes difference depends on the current and real values of the output signal of control means, as well as on the influencing parameter deviation. The method allows calculating the real values of the measured parameter only by the output signal of control means and the current values of the influencing parameter. The dependencies between the real value of the measured parameter, the current value of the output signal of control means and the influencing parameter deviation are established.

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Gorbachev, Alexey. "Overview of the route public transport mathematical models." Proceedings of Petersburg Transport University, no. 3 (September 20, 2018): 366–70. http://dx.doi.org/10.20295/1815-588x-2018-3-366-370.

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Objective: To survey international and domestic experience of building mathematical models for timetable and schedule presentation. Methods: The analysis of applicability of the current international experience in transport management in the sphere of public route transport was carried out. It particularly concerned scheduling for ex-USSR countries. Results: The necessity to develop special-purpose mathematical models of route public transport schedule was justified. The schedule models in question being serviceable under the limitations of current technology-based standards and traffic management restrictions in Russia. Practical importance: Implementation and development of domestic intelligence systems, designed to organize the management of public route transport operation, is of great relevance for economic development of the country.

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Nijsse, Femke J. M. M., and Henk A. Dijkstra. "A mathematical approach to understanding emergent constraints." Earth System Dynamics 9, no. 3 (August 15, 2018): 999–1012. http://dx.doi.org/10.5194/esd-9-999-2018.

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Abstract. One of the approaches to constrain uncertainty in climate models is the identification of emergent constraints. These are physically explainable empirical relationships between a particular simulated characteristic of the current climate and future climate change from an ensemble of climate models, which can be exploited using current observations. In this paper, we develop a theory to understand the appearance of such emergent constraints. Based on this theory, we also propose a classification for emergent constraints, and applications are shown for several idealized climate models.

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Brushlinskii, K. V., and E. V. Stepin. "Mathematical Models of Equilibrium Configurations of Plasma Surrounding Current-Carrying Conductors." Differential Equations 56, no. 7 (July 2020): 872–81. http://dx.doi.org/10.1134/s001226612007006x.

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Leonov, Aleksandr V., Nikolai N. Filatov, and Vladimir S. Titov. "The estimation of current state of Lake Ladoga using mathematical models." Hydrobiologia 322, no. 1-3 (April 1996): 103–8. http://dx.doi.org/10.1007/bf00031813.

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Wang, Jin. "Mathematical Models for Cholera Dynamics—A Review." Microorganisms 10, no. 12 (November 29, 2022): 2358. http://dx.doi.org/10.3390/microorganisms10122358.

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Cholera remains a significant public health burden in many countries and regions of the world, highlighting the need for a deeper understanding of the mechanisms associated with its transmission, spread, and control. Mathematical modeling offers a valuable research tool to investigate cholera dynamics and explore effective intervention strategies. In this article, we provide a review of the current state in the modeling studies of cholera. Starting from an introduction of basic cholera transmission models and their applications, we survey model extensions in several directions that include spatial and temporal heterogeneities, effects of disease control, impacts of human behavior, and multi-scale infection dynamics. We discuss some challenges and opportunities for future modeling efforts on cholera dynamics, and emphasize the importance of collaborations between different modeling groups and different disciplines in advancing this research area.

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Bali, Rekha, Bhawini Prasad, and Swati Mishra. "A REVIEW ON MATHEMATICAL MODELS FOR NANOPARTICLE DELIVERY IN THE BLOOD." International Journal of Advanced Research 10, no. 04 (April 30, 2022): 130–46. http://dx.doi.org/10.21474/ijar01/14526.

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One of the ubiquitous causes of deaths are the Cardio Vascular Diseases or CVDs. The implementation of nanotechnology in the treatment of CVDs has evinced better bio-compatibility and enhanced cell interactions. This provides a strong potential for their mathematical modeling with the diseased blood vessels. In our current study we have reported various mathematical models used for the treatment of CVDs employing nanotechnology. Mathematical modeling provides a tool to comprehend the type, shape and size of the nanoparticles that can be employed as possible drug delivery systems. Mathematical models help to predict how nano-drugs have many improvements like expanded drug loading capacity and programmable pharmo-kinetic properties over the conventional drugs. The amalgamation of mathematical models with clinical data provides for designing these optimal therapies. This review encapsulates the current state of mathematical modeling approaches to treat CVDs using nanoparticle targeted drug delivery.

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Bali, Rekha, Bhawini Prasad, and Swati Mishra. "A REVIEW ON MATHEMATICAL MODELS FOR NANOPARTICLE DELIVERY IN THE BLOOD." International Journal of Advanced Research 10, no. 04 (April 30, 2022): 130–46. http://dx.doi.org/10.21474/ijar01/14526.

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One of the ubiquitous causes of deaths are the Cardio Vascular Diseases or CVDs. The implementation of nanotechnology in the treatment of CVDs has evinced better bio-compatibility and enhanced cell interactions. This provides a strong potential for their mathematical modeling with the diseased blood vessels. In our current study we have reported various mathematical models used for the treatment of CVDs employing nanotechnology. Mathematical modeling provides a tool to comprehend the type, shape and size of the nanoparticles that can be employed as possible drug delivery systems. Mathematical models help to predict how nano-drugs have many improvements like expanded drug loading capacity and programmable pharmo-kinetic properties over the conventional drugs. The amalgamation of mathematical models with clinical data provides for designing these optimal therapies. This review encapsulates the current state of mathematical modeling approaches to treat CVDs using nanoparticle targeted drug delivery.

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AFANAS’YEV, Alexander A. "The Mathematical Models of Converter Fed Permanent Magnet Motors." Elektrichestvo 2, no. 2 (2021): 66–70. http://dx.doi.org/10.24160/0013-5380-2021-2-66-70.

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The mathematical models of converter fed permanent magnet motors written in the coordinate axes are considered. Owing to pulse-width modulation, the currents and voltages of the motors are assumed to be sinusoidal. In the models with two state equations, the stator current is represented only by its quadrature-axis component, and the variable load angle appears in explicit or implicit form. These equations are most close to the similar equations of dc commutator motors. Third-order equations contain both stator current components; the load angle in them is fixed as constant one or varies to maintain the unity power factor for an arbitrary load. The models constructed in the form of state equations of the appropriate order, which are implemented in the MathCad software, illustrate possible functional regimes of the motor and indicate the ways of their possible implementations using means known from the practice.

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AMMARI, HABIB, YVES CAPDEBOSCQ, HYEONBAE KANG, and ANASTASIA KOZHEMYAK. "Mathematical models and reconstruction methods in magneto-acoustic imaging." European Journal of Applied Mathematics 20, no. 3 (June 2009): 303–17. http://dx.doi.org/10.1017/s0956792509007888.

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In this paper, we provide the mathematical basis for three different magneto-acoustic imaging approaches (vibration potential tomography, magneto-acoustic tomography with magnetic induction and magneto-acoustic current imaging) and propose new algorithms for solving the inverse problem for each of them.

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COEN, P. G., P. T. HEATH, M. L. BARBOUR, and G. P. GARNETT. "Mathematical models of Haemophilus influenzae type b." Epidemiology and Infection 120, no. 3 (June 1998): 281–95. http://dx.doi.org/10.1017/s0950268898008784.

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A review of empirical studies and the development of a simple theoretical framework are used to explore the relationship between Haemophilus influenzae type b (Hib) carriage and disease within populations. The models emphasize the distinction between asymptomatic and symptomatic infection. Maximum likelihood methods are used to estimate parameter values of the models and to evaluate whether models of infection and disease are satisfactory. The low incidence of carriage suggests that persistence of infection is only compatible with the absence of acquired immunity to asymptomatic infection. The slight decline in carriage rates amongst adults is compatible with acquired immunity, but could be a consequence of reduced contacts. The low rate of disease observed in adulthood cannot be explained if protection from disease is a product of previous detectable exposure to Hib alone. We estimate an Ro of 3·3 for Hib in developed countries, which suggests that current immunization programmes may eliminate the infection. Analysis of the disease data set suggests the absence of maternal immunity and increased susceptibility to disease in the oldest age classes.

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Pavlov, V. D. "Mathematical models of resonance and antiresonance processes." Herald of the Ural State University of Railway Transport, no. 1 (2021): 17–27. http://dx.doi.org/10.20291/2079-0392-2021-1-17-27.

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The use of the symbolic (complex) method has significantly simplified the study of resonance and near-resonance phenomena, in particular, it has made it possible to deeply unify and formalize the consideration of various mechanical systems. The cumbersome and time-consuming operations associated with composing and solving differential equations have been replaced by simple algebraic transformations. The method is based on the mechanical analogue of Ohm’s law in a complex representation and the concept of mechanical reactance, resistance, impedance, susseptance, conductance and admittance. Resonances and antiresonances of forces and velocities are determined. Resonances occur when the elements are connected in parallel with a force source, or when the elements are connected in series with a velocity source. Antiresonances occur when a parallel connection and a speed source are combined, or a serial connection and a force source are combined. These concepts are a generalization to mechanics of the concepts of «voltage source» and «current source» from theoretical electrical engineering. The closest to the source of speed in its properties is a crank-rocker (connecting rod) mechanism with a massive flywheel. The source of force corresponds more to the rod of the significantly smaller of the two connected pneumatic cylinders.

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Sawicki, Antoni. "Diagnostics of Electric Arc versus the Development of Universal Mathematical Models." Biuletyn Instytutu Spawalnictwa, no. 6 (December 2021): 47–57. http://dx.doi.org/10.17729/ebis.2021.6/5.

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The article presents universal mathematical static current-voltage characteristics- based models of electric arc and indicates primary issues concerned with arc diagnostics related to the determination of the above-named models. Particular attention was paid to the experimental determination of AC-powered arc voltage. Diagnostics-related purposes involved the use of bridge systems with one or two sources of current. Computer-aided simulations involving sinusoidal and trapezoidal current-based excitations made it possible to demonstrate the possibility of obtaining minimum values of bridge unbalance voltage. Such a condition indicated the proper determination of AC-powered arc ignition voltage.

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Lu, James, Norman A. Mazer, and Katrin Hübner. "Mathematical models of lipoprotein metabolism and kinetics: current status and future perspective." Clinical Lipidology 8, no. 5 (October 2013): 595–604. http://dx.doi.org/10.2217/clp.13.52.

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Swift, G. "Discussion of "mathematical models for current, voltage, and coupling capacitor voltage transformers"." IEEE Transactions on Power Delivery 16, no. 4 (October 2001): 827. http://dx.doi.org/10.1109/tpwrd.2001.956791.

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Gondarenko, N. A., T. A. Golub, and A. M. Iskoldsky. "Mathematical models of high-current pulse generators with closing and opening switches." IEEE Transactions on Plasma Science 20, no. 6 (1992): 967–72. http://dx.doi.org/10.1109/27.199560.

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Quintanilla, Sacramento, Francisco Ballestín, and Ángeles Pérez. "Mathematical models to improve the current practice in a Home Healthcare Unit." OR Spectrum 42, no. 1 (October 18, 2019): 43–74. http://dx.doi.org/10.1007/s00291-019-00565-w.

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Verkerk, Arie O., and Ronald Wilders. "Hyperpolarization-Activated Current, , in Mathematical Models of Rabbit Sinoatrial Node Pacemaker Cells." BioMed Research International 2013 (2013): 1–18. http://dx.doi.org/10.1155/2013/872454.

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A typical feature of sinoatrial (SA) node pacemaker cells is the presence of an ionic current that activates upon hyperpolarization. The role of this hyperpolarization-activated current, , which is also known as the “funny current” or “pacemaker current,” in the spontaneous pacemaker activity of SA nodal cells remains a matter of intense debate. Whereas some conclude that plays a fundamental role in the generation of pacemaker activity and its rate control, others conclude that the role of is limited to a modest contribution to rate control. The ongoing debate is often accompanied with arguments from computer simulations, either to support one's personal view or to invalidate that of the antagonist. In the present paper, we review the various mathematical descriptions of that have been used in computer simulations and compare their strikingly different characteristics with our experimental data. We identify caveats and propose a novel model for based on our experimental data.

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Webster, Molly, and Vikram Sheel Kumar. "Mathematical Models to Enhance the Value of Information from Current Laboratory Platforms." Clinical Chemistry 58, no. 3 (March 1, 2012): 651–53. http://dx.doi.org/10.1373/clinchem.2011.179051.

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Stamou, A. I., M. Latsa, and D. Assimacopoulos. "Design of two-storey final settling tanks using mathematical models." Journal of Hydroinformatics 2, no. 4 (October 1, 2000): 235–45. http://dx.doi.org/10.2166/hydro.2000.0021.

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A mathematical model is applied to the design of two-storey final settling tanks. Computations show that the flow and suspended solids (SS) concentration fields for the upper and bottom tanks are similar. The flow field has the ‘two-layer’ structure, observed in real and laboratory settling tanks, consisting of a bottom current and a free surface return current with approximately equal heights. The SS concentration field is governed by the flow field (and vice versa). The SS concentration profiles are uniform in the major part of the tanks. The hydraulic and SS removal efficiencies improve with decreasing flow rate. In both tanks the outlet SS concentrations are lower than the maximum permissible value (20 mg l−1), with the upper tank showing a better performance than the bottom tank.

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Forger, M., J. Laartz, and U. Schäper. "Current algebra of classical non-linear sigma models." Communications in Mathematical Physics 146, no. 2 (May 1992): 397–402. http://dx.doi.org/10.1007/bf02102634.

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Abdalla, E., M. C. B. Abdalla, O. H. G. Branco, and L. E. Saltini. "Current algebra of super WZNW models." Journal of Physics A: Mathematical and General 27, no. 13 (July 7, 1994): 4709–15. http://dx.doi.org/10.1088/0305-4470/27/13/043.

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Kan, Edwin C., Zhiping Yu, Robert W. Dutton, Datong Chen, and Umberto Ravaioli. "Formulation of Macroscopic Transport Models for Numerical Simulation of Semiconductor Devices." VLSI Design 3, no. 2 (January 1, 1995): 211–24. http://dx.doi.org/10.1155/1995/12686.

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According to different assumptions in deriving carrier and energy flux equations, macroscopic semiconductor transport models from the moments of the Boltzmann transport equation (BTE) can be divided into two main categories: the hydrodynamic (HD) model which basically follows Bløtekjer's approach [1, 2], and the Energy Transport (ET) model which originates from Strattton's approximation [3, 4]. The formulation, discretization, parametrization and numerical properties of the HD and ET models are carefully examined and compared. The well-known spurious velocity spike of the HD model in simple nin structures can then be understood from its formulation and parametrization of the thermoelectric current components. Recent progress in treating negative differential resistances with the ET model and extending the model to thermoelectric simulation is summarized. Finally, we propose a new model denoted by DUET (Dual ET)which accounts for all thermoelectric effects in most modern devices and demonstrates very good numerical properties. The new advances in applicability and computational efficiency of the ET model, as well as its easy implementation by modifying the conventional drift-diffusion (DD) model, indicate its attractiveness for numerical simulation of advanced semiconductor devices

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DUMAS, A., J. DIJKSTRA, and J. FRANCE. "Mathematical modelling in animal nutrition: a centenary review." Journal of Agricultural Science 146, no. 2 (February 21, 2008): 123–42. http://dx.doi.org/10.1017/s0021859608007703.

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SUMMARYA centenary review presents an opportunity to ponder over the processes of concept development and give thought to future directions. The current review aims to ascertain the ontogeny of current concepts, underline the connection between ideas and people and pay tribute to those pioneers who have contributed significantly to modelling in animal nutrition. Firstly, the paper draws a brief portrait of the use of mathematics in agriculture and animal nutrition prior to 1925. Thereafter, attention turns towards the historical development of growth modelling, feed evaluation systems and animal response models. Introduction of the factorial and compartmental approaches into animal nutrition is noted along with the particular branches of mathematics encountered in various models. Furthermore, certain concepts, especially bioenergetics or the heat doctrine, are challenged and alternatives are reviewed. The current state of knowledge of animal nutrition modelling results mostly from the discernment and unceasing efforts of our predecessors rather than serendipitous discoveries. The current review may stimulate those who wish for greater understanding and appreciation.

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Krykowski, Krzysztof, and Janusz Hetmańczyk. "Constant Current Models of Brushless DC Motor." Electrical, Control and Communication Engineering 3, no. 1 (August 1, 2013): 19–24. http://dx.doi.org/10.2478/ecce-2013-0010.

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Abstract Two constant current models of Permanent Magnet Brushless Direct Current Motor (PM BLDC) are presented in the paper. In the first part of the paper principle of operation, basic properties and mathematical equations describing PM BLDC models are given. Then, two different constant current models of PM BLDC motor are considered: In the first model, PM BLDC motor is approximated with dc motor; in the second model, modified constant current model is applied with additional block, which is used to take into account the impact of inductance on torque-speed characteristics. In order to verify these models, torque-speed characteristics have been determined and compared for different motor supply voltages. After running a series of simulation and laboratory tests, we have found that this modified model (which makes allowance for the influence of inductance on torque-speed characteristics) ensures obtaining torque-speed characteristics identical to those of the real motor. Therefore, this model may be recommended for those simulation tests which do not consider effects occurring inside the electronic commutator-motor circuit. However, approximation of PM BLDC motor with dc motor is not recommended in computer tests.

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Zhang, Yiqi, and Changxu Wu. "Learn to Integrate Mathematical Models in Human Performance Modeling." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 61, no. 1 (September 2017): 776–80. http://dx.doi.org/10.1177/1541931213601678.

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The current paper provided a tutorial of the integration of mathematical models in human performance modeling. It introduced the unique features of mathematical modeling in human performance, and the steps in mathematical model integration, including how the literature of models was reviewed, how a research gap was identified, and how a mathematical model was developed and integrated based on existing models, and how a model was validated via an experimental study. A case study was presented by following each step to illustrate the integration of several existing models to derive a new model of drivers’ braking performance in warning response with its integration with the existing mathematical models of driver speed control in normal situations and the model of humans’ warning response time. This is the first tutorial work that provided a detailed explanation of the steps in mathematical model integration with a case study in human performance modeling. It could be used as guidance for human factors professionals to learn the mathematical modeling approaches and will benefit the field of human performance modeling.

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Zhang, Yuman, Gang Dou, Zhao Sun, Mei Guo, and Yuxia Li. "Establishment of Physical and Mathematical Models for Sr0.95Ba0.05TiO3Memristor." International Journal of Bifurcation and Chaos 27, no. 09 (August 2017): 1750148. http://dx.doi.org/10.1142/s0218127417501486.

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The Sr[Formula: see text]Ba[Formula: see text]TiO3(SBT) memristor is prepared using the monolayer Sr[Formula: see text]Ba[Formula: see text]TiO3nano-film structure. In order to apply it into the nonlinear circuit design, the SBT memristor is modeled in the paper. The voltage-controlled physical model of the SBT memristor is established based on its working mechanism. Due to the difficulty in determining the accurate parameters of the voltage-controlled physical model, a flux-controlled mathematical model of the SBT memristor is proposed, and its equivalence relation with the voltage-controlled physical model is proved. Moreover, the parameters of the flux-controlled mathematical model are determined by means of the quadratic polynomial interpolation method using the experimentally measured voltage and current data of the SBT memristor. The simulated [Formula: see text]–[Formula: see text] characteristic curve using the flux-controlled mathematical model coincides well with the measured [Formula: see text]–[Formula: see text] characteristic curves. The result indicates that the flux-controlled mathematical model with the definite parameters can be used to characterize the behaviors of the physical SBT memristor and guide its application to nonlinear circuit design.

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Arenas, Alex, Jesús Gómez-Gardeñes, Clara Granell, and David Soriano-Paños. "Epidemic spreading: Tailored models for COVID-19." Europhysics News 51, no. 5 (September 2020): 38–40. http://dx.doi.org/10.1051/epn/2020507.

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A very simple epidemic model proposed a century ago is the linchpin of the current mathematical models of the epidemic spreading of the COVID-19. Nowadays, the abstracted compartmentalisation of the population in susceptible, infected and recovered individuals, combined with precise information about the networks of mobility flows within geographical territories, is the best weapon of the physics community to forecast the possible evolution of contagions in the current pandemic scenario.

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Stikhova, Olga. "Mathematical Estimation Methods and Models for Industrial Companies." EPJ Web of Conferences 248 (2021): 03001. http://dx.doi.org/10.1051/epjconf/202124803001.

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The collateralized debt obligations and credit default swaps applications are shown in this paper. The industry obligations secondary market risk estimation methods are considered in this work. The new methods taking into account statistically significant parameters for industrial credit derivatives portfolio are offered for single-name investment risks numerical experiments realization. The mathematical estimation of tranche were shown. The single and multiple name default obligations necessary mathematical modeling methods and formulae for the industrial materials manufacturers derivative credit tools market are shown. It is determined that the portfolio of synthetic debt tools is made of the given parameters. The task of a loss derivative tranches mathematical estimation is solved. Late defaults raise the equity tranches payment required sums with high spreads, early defaults reduce. Also the functional characteristics required for an estimation huge debts problem solving are partly considered in this paper. The problem of the default modeling for market tools and numerical simulation of the obligations influence on conditions of current bistability mode are shown here. Some credit derivatives of industrial manufacturers are demonstrated in the modeling process of default as an example. It is found that the model is an additional factor help us to estimate the default opportunity.

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Yoo, Donghoon, and Brian A. O'Connor. "MATHEMATICAL MODELLING OF WAVE-INDUCED NEARSHORE CIRCULATIONS." Coastal Engineering Proceedings 1, no. 20 (January 29, 1986): 122. http://dx.doi.org/10.9753/icce.v20.122.

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The paper presents a mathematical model for describing wave climate and wave-induced nearshore circulations. The model accounts for current-depth refraction, diffraction, wave-induced currents, set-up and set-down, mixing processes and bottom friction effects on both waves and currents. The present model was tested against published experimental data on wave conditions within a model harbour and shown to give very good results for both wave and current fields. The importance of including processes such as advection, flooding and current-interaction in coastal models was demonstrated by comparing the numerical results without each process to the results from the complete scheme.

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Krasiuk, Bohdan Vitaliyovych, and Anatoliy Pavlovich Vlasyuk. "Mathematical modeling of a one-dimensional demographic process." Modeling, Control and Information Technologies, no. 4 (October 22, 2020): 23–24. http://dx.doi.org/10.31713/mcit.2020.33.

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The specifics of the current stage of society connects with significant changes in directions and internal scales and interstate migration of the population. In this regard population migration processes between the two states are exploring in a one-dimensional case. Now the scientific literature offers different mathematical models of these processes [1]. However, we will use diffusion models for modeling these processes.

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Oravec, Jakub, Ondřej Šikula, and Iva Nováková. "An Evaluation of the Mathematical Models of Energy Piles." Slovak Journal of Civil Engineering 28, no. 1 (March 1, 2020): 44–48. http://dx.doi.org/10.2478/sjce-2020-0006.

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AbstractA current trend is to reduce the energy performance of buildings by using alternative sources for heating and cooling. One of the most promising, and so far unprecedented sources of heating and cooling, is the use of energy from the earth using the thermally-activated foundation piles of a building, the so-called energy piles. The paper deals with an overview and comparison of computer-aided analytical models of energy piles. The individual analytical models are compared (categorized) from the point of view of their physical complexity, computational costs, and thus their usability for the purpose of optimizing energy-pile equipment or assessing the long-term energy efficiency of an energy pile field. Selected mathematical models were algorithmized, and the results obtained were compared with a more robust numerical solution performed using CalA 4 software.

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Grover, James P., Jason W. Baker, Daniel L. Roelke, and Bryan W. Brooks. "Current Status of Mathematical Models for Population Dynamics ofPrymnesium parvumin a Texas Reservoir1." JAWRA Journal of the American Water Resources Association 46, no. 1 (February 2010): 92–107. http://dx.doi.org/10.1111/j.1752-1688.2009.00393.x.

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Eftimie, Raluca, Joseph J. Gillard, and Doreen A. Cantrell. "Mathematical Models for Immunology: Current State of the Art and Future Research Directions." Bulletin of Mathematical Biology 78, no. 10 (October 2016): 2091–134. http://dx.doi.org/10.1007/s11538-016-0214-9.

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Appiah, S. T., Albert Buabeng, and B. Odoi. "Comparative Study of Mathematical Models for Ghana’s Gold Production." Ghana Mining Journal 18, no. 1 (June 28, 2018): 78–83. http://dx.doi.org/10.4314/gm.v18i1.10.

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Sigmoid functions were used to approximate the cumulative gold production in Ghana. The functions examined were the logistic, Gompertz, Gaussian, Probit and the Hill, which were then used to predict into the future. Although all the five approximated models gave a good estimation of the reality, the Gompertz function was identified to give the best approximation of the observed trend of gold production in Ghana. The model was selected based on its high proportion of variance explained (R2 = 0.9402) as well as having the least value in terms of error (RMSE) and information loss (AIC). The model suggested that gold production could escalate to a level of 7040813 Oz in the future. It also showed that, industrial scale production of gold should be possible even after the year 2050 provided the current upward trend of gold production in Ghana continues. Keywords: Sigmoid, Logistic, Gompertz, Gaussian, Probit, Hill, Gold

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Jiang, Zhou Hua, Jia Yu, Fu Bin Liu, Xu Chen, and Xin Geng. "Application of Mathematical Models for Different Electroslag Remelting Processes." High Temperature Materials and Processes 36, no. 4 (April 1, 2017): 411–26. http://dx.doi.org/10.1515/htmp-2016-0146.

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AbstractThe electroslag remelting (ESR) process has been effectively applied to produce high grade special steels and super alloys based on the controllable solidification and chemical refining process. Due to the difficulties of precise measurements in a high temperature environment and the excessive expenses, mathematical models have been more and more attractive in terms of investigating the transport phenomena in ESR process. In this paper, the numerical models for different ESR processes made by our lab in last decade have been introduced. The first topic deals with traditional ESR process predicting the relationship between operating parameters and metallurgical parameters of interest. The second topic is concerning the new ESR technology process including ESR with current-conductive mould (CCM), ESR hollow ingot technology, electroslag casting with liquid metal(ESC LM), and so on. Finally, the numerical simulation of solidification microstructure with multi-scale model is presented, which reveals the formation mechanism of microstructure.

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

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

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Revoredo, Dhiego Henrique Ferreira, Ana Cecília Vieira Nobrega, Arnaldo Manoel Pereira Carneiro, and João Emanuell Araújo Marciano. "A Review Predictive Mathematical Modeling of Alkali-Silica Reaction in Concrete: evolution, current understanding and the knowledge gaps." Research, Society and Development 10, no. 11 (September 6, 2021): e449101119810. http://dx.doi.org/10.33448/rsd-v10i11.19810.

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Predictive mathematical models have been proposed in alkali-silica reaction (ASR). Predicting concrete degradation and its effects on mechanical properties is of interest given the long time until degradation becomes critical for intervention and recovery, and difficult structural access for predictive and corrective monitoring and treatment. The present paper presents a general overview of the evolution of the aforementioned predictive mathematical models, interrelating them to the maturation of the phenomenological state of the art associated with ASR. For this purpose, a systematic literature review was used, followed by bibliometric analysis and meta-analysis. In this study, 104 articles from 1974 to 2020 were selected, of which 31 articles were reviewed on the topic of mathematical modeling of ASR. The results of the method indicated the importance of the methodological approach of literature review to provide a comprehensive and chronological view of the evolution of ASR consolidated in the literature. It was found that the mathematical models have evolved considering the phenomenological approach of ASR.

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Chen, Hong Jiang, and Yue Hai Wu. "Study of Material’s Creep Relaxation Capability." Applied Mechanics and Materials 121-126 (October 2011): 406–10. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.406.

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Creep relaxation is an important form of system failure, how to understand and analyze the effect of creep relaxation, to solve system failures and improve economic efficiency are of great significance. The paper describe researches of creep relaxation , mathematical models and theories at home and abroad in detail, and introduce the finite element method applied in this field. By comparing with the mathematical models, finite element Methods with test results, improving current mathematical models and utilizing finite element method is an important trend.

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Wu, L. M., Nan Hui Lai, and G. T. Wang. "Measurement and Simulation of Automotive Eddy Current Retarder Based on Virtual Reality." Key Engineering Materials 392-394 (October 2008): 93–97. http://dx.doi.org/10.4028/www.scientific.net/kem.392-394.93.

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Structure and working principles of eddy current retarder (ECR) are discussed, as well as performance requirements of real-time virtual testing and simulation. On the basis of hardware testing platform, virtual models of vehicle and retarder are embedded into application program. In the testing system, Vega API function library is used for second development to control the 3D models, and Visual C++ is used for mathematical models call from MATLAB to simulate the working condition. Integrated with virtual instrument and virtual environment, the limitation of former simulation is broken through. Monitoring and testing on eddy current retarder are achieved efficiently and visually. Besides, the virtual test data is not only compared with the practical vehicle test data to correct the technical parameter of eddy current retarder, but also compared with the simulation of mathematical models for further study. The testing system gives evaluation on the performance of the retarder in different vehicles, so it expands application range and heightens testing efficiency.

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Hacia, L. "MATHEMATICAL MODELLING IN ELECTRICAL ENGINEERING." Mathematical Modelling and Analysis 10, no. 3 (September 30, 2005): 257–74. http://dx.doi.org/10.3846/13926292.2005.9637286.

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Various problems of electrical engineering lead to mathematical models being difference, differential or integral equations. In this paper some mathematical models in certain problems of electrical engineering are presented. Our considerations are restricted to the radiative heat transfer and density theory (Fredholm integral equations). Respecting time in current density problems we get integro‐differential equations or generally Volterra‐Predholm integral equations (heat‐conduction theory). The new numerical method for these equations is analysed. Daugelio elektros inžinerijos problemu sprendimui tenka sudaryti matematinius modelius, kurie dažniausiai būna aprašomi skirtuminemis, diferencialinemis ar integralinemis lygtimis. Šiame darbe apžvelgiami kai kurie modeliai, skirti konkrečiu elektros inžinerijos uždaviniu sprendimui. Apsiribojama šilumos perdavimo proceso su spinduliuote modeliavimu ir tankio pasiskirstymo teorija (Predholmo integralines lygtys) .Ivedus laika, lygtys tankiui tampa integr‐diferencialinemis arba Volteros‐Predholmo integralinemis lygtimis. Darbe pateikiamas ir nagrinejamas naujas skaitinis tokiu lygčiu sprendimo metodas.

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Konstorum, Anna, Anthony T. Vella, Adam J. Adler, and Reinhard C. Laubenbacher. "Addressing current challenges in cancer immunotherapy with mathematical and computational modelling." Journal of The Royal Society Interface 14, no. 131 (June 2017): 20170150. http://dx.doi.org/10.1098/rsif.2017.0150.

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The goal of cancer immunotherapy is to boost a patient's immune response to a tumour. Yet, the design of an effective immunotherapy is complicated by various factors, including a potentially immunosuppressive tumour microenvironment, immune-modulating effects of conventional treatments and therapy-related toxicities. These complexities can be incorporated into mathematical and computational models of cancer immunotherapy that can then be used to aid in rational therapy design. In this review, we survey modelling approaches under the umbrella of the major challenges facing immunotherapy development, which encompass tumour classification, optimal treatment scheduling and combination therapy design. Although overlapping, each challenge has presented unique opportunities for modellers to make contributions using analytical and numerical analysis of model outcomes, as well as optimization algorithms. We discuss several examples of models that have grown in complexity as more biological information has become available, showcasing how model development is a dynamic process interlinked with the rapid advances in tumour–immune biology. We conclude the review with recommendations for modellers both with respect to methodology and biological direction that might help keep modellers at the forefront of cancer immunotherapy development.

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Cheng, Qilong, Tiancheng Yu, Jingkai Yan, and Ru Wang. "Mathematical Models of Refugee Immigration and Recommendations of Policies." Journal of Mathematics Research 8, no. 6 (November 25, 2016): 85. http://dx.doi.org/10.5539/jmr.v8n6p85.

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Over the past two years, the refugee crisis resulted from the racial conflict, persecution, generalized violence and violations of human rights has forced an enormous number of refugees to flee to Europe. Aiming to address the problem caused by the flow of refugees, we analyzed the actual procedure of their movement and divide it into three major stages. We designed the gathering model, the entering model, the transferring model, even the health and safety model. Finally, we used the models described above to complete our assigned tasks. Also we put forward seven major policy recommendations to the committee. We accompanied every policy with a straightforward explanation so that people without any technical background can easily understand our insights. The main strength of our model is that it can forecast the flow of immigration and provide meaningful suggestions policies for refugees. With the help of modern computing software, we can track the current tendency and make judges efficiently.

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Jiang, Yu, Yanshuo Ni, Hexi Baoyin, Junfeng Li, and Yongjie Liu. "Asteroids and Their Mathematical Methods." Mathematics 10, no. 16 (August 12, 2022): 2897. http://dx.doi.org/10.3390/math10162897.

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In this paper, the basic classification of asteroids and the history and current situation of asteroid exploration are introduced. Furthermore, some recent research progress on the orbital dynamics of asteroids, including models of the gravitational potential field, the dynamics near asteroids, hopping motion on the surface, and bifurcations under varying external parameters, is reviewed. In the meanwhile, the future research development such as the configuration and evolution of binary or triple asteroid systems and near-Earth asteroid defense is briefly discussed.

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Journal articles on the topic 'El Niño current Mathematical models'

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