Standard Solution Methods Research Articles

Inverse Methods in Thermal Radiation Analysis and Experiment

Abstract Most thermal radiation problems are analyzed in a “forward” manner, in which the aim is to predict the response of a system based on well-defined boundary conditions. In practice, however, many thermal radiation problems are inverse problems. For example, the goal of many furnace design problems is to find a configuration that realizes a particular irradiation profile on a target, while in measurement problems, transmitted or reflected radiation measured with sensors at a boundary may be used to infer the properties of matter within the boundary. Such inverse problems are often mathematically ill-posed because they may have multiple solutions or no solution at all. Consequently, analyzing these types of problems is more complex than is required for forward problems. In this review, we examine the various types and characteristics of inverse problems, outline standard inverse solution methods for them, and review the historical and contemporary literature.

On some methods for solving the problem of power distribution of data transmission channels taking into account fuzzy constraints on consumption volumes

The article deals with the mathematical formulation of the problem of optimal distribution of the power of data transmission channels in information and computer networks with a three-level architecture and fuzzy restrictions on consumption volumes. An efficient algorithm has been developed for solving the problem, the peculiarity of which is the inability to meet the end user’s needs at the expense of the resources of different suppliers. A standard solution method based on a fuzzy optimization problem of mathematical programming is considered. A constructive variant of finding a solution based on the backtracking method is proposed. Computational experiments have been carried out. The developed approach was used to determine the optimal configuration of a three-level information and computer network with a given number of communication servers.

Solution of ill-posed problems with Chebfun

The analysis of linear ill-posed problems often is carried out in function spaces using tools from functional analysis. However, the numerical solution of these problems typically is computed by first discretizing the problem and then applying tools from finite-dimensional linear algebra. The present paper explores the feasibility of applying the Chebfun package to solve ill-posed problems with a regularize-first approach numerically. This allows a user to work with functions instead of vectors and with integral operators instead of matrices. The solution process therefore is much closer to the analysis of ill-posed problems than standard linear algebra-based solution methods. Furthermore, the difficult process of explicitly choosing a suitable discretization is not required.

Tunneling potentials for the tunneling action: gauge invariance

We formulate a procedure to obtain a gauge-invariant tunneling rate at zero temperature using the recently developed tunneling potential approach. This procedure relies on a consistent power counting in gauge coupling and a derivative expansion. The tunneling potential approach, while numerically more efficient than the standard bounce solution method, inherits the gauge-dependence of the latter when naïvely implemented. Using the Abelian Higgs model, we show how to obtain a tunneling rate whose residual gauge-dependence arises solely from the polynomial approximations adopted in the tunneling potential computation.

Multi-Armed Bandits in Brain-Computer Interfaces.

The multi-armed bandit (MAB) problem models a decision-maker that optimizes its actions based on current and acquired new knowledge to maximize its reward. This type of online decision is prominent in many procedures of Brain-Computer Interfaces (BCIs) and MAB has previously been used to investigate, e.g., what mental commands to use to optimize BCI performance. However, MAB optimization in the context of BCI is still relatively unexplored, even though it has the potential to improve BCI performance during both calibration and real-time implementation. Therefore, this review aims to further describe the fruitful area of MABs to the BCI community. The review includes a background on MAB problems and standard solution methods, and interpretations related to BCI systems. Moreover, it includes state-of-the-art concepts of MAB in BCI and suggestions for future research.

AN EFFICIENT METHOD FOR SOLVING THE PROBLEM OF CHANNEL POWER DISTRIBUTION TAKING INTO ACCOUNT FUZZY CONSTRAINTS ON CONSUMPTION VOLUMES

Context. An efficient algorithm has been developed for solving the problem of rational distribution of the power of data transmission channels with fuzzy restrictions on consumption volumes. A standard solution method based on a fuzzy optimization problem is considered. A constructive variant of finding a solution based on the backtracking method is proposed.
 Objective. The goal of the work is to develop an algorithm for solving the problem of rational distribution of the power of data transmission channels with fuzzy restrictions on consumption volumes based on the backtracking method.
 Method. This paper The article proposes a method for solving the problem of rational distribution of the power of data transmission channels, taking into account fuzzy restrictions on consumption volumes. A feature of such tasks is the inability to meet the needs of the end user at the expense of the resources of different suppliers. The method of solution based on fuzzy problems of mathematical programming is considered. A constructive algorithm for solving the problem based on the backtracking method has been developed. Computational experiments have been carried out.
 Results. The developed method for solving the problem of rational distribution of data transmission channel capacities, taking into account fuzzy restrictions on consumption volumes, made it possible to solve the problem of constructing an optimal configuration of a three-level information and computer network with a given number of communication servers and taking into account fuzzy consumption volumes. 
 Conclusions. Methods for solving the problem with fuzzy restrictions on the consumption volumes of end users are investigated. A fuzzy optimization problem is formulated, which allows taking into account the interval specified volumes for the connection values. A variant of solving fuzzy optimization problems in the case of using fuzzy numbers is proposed. A multi-criteria problem of efficient distribution of communication channel powers with fuzzy restrictions is formulated. A variant of the algorithm with a return is proposed, which allows solving the obtained problem. The approach is illustrated by a number of numerical examples for the problem of forming a network structure with a given number of end users and different allowable bandwidths of communication servers.

Solving linear rational expectations models in the presence of structural change: Some extensions

Standard solution methods for linear rational expectations models assume a time-invariant structure. Recent work has gone beyond this by formulating solution methods for linear rational expectations models subject to structural changes, such as parameter shifts and policy reforms, that are announced in advance. This paper contributes to this literature by presenting solutions for some cases – imperfectly credible policy reforms; delayed announcement to some fraction of agents; and indeterminacy of the terminal solution (multiple equilibria) – that received little attention so far. These solutions are illustrated using several applications, including a New Keynesian model in which the Taylor principle is not satisfied by the terminal structure.

Comparison of cooling strategies in simulated annealing algorithms for flow-shop scheduling

Flow-shop scheduling is considered. The order of operations must be the same for each job to minimize the maximum completion time. The Simulated Annealing algorithm is a standard approximate solution method in scheduling and optimization in general. Since the algorithm depends on cooling as a heuristic to generate better approx- imations, choosing the strategy with which the temperature decreases can affect the final result.

Resilient Adaptive Parallel sImulator for griD (RAPID): An Open Source Power System Simulation Toolbox

This paper describes an open source power system simulation toolbox: Resilient Adaptive Parallel sImulator for griD (RAPID), a package of Python codes that implements an advanced power system dynamic simulation framework. The main function of RAPID is time-domain simulation, and it contains details of the solution process, including the quasi-steady-state power flow analysis, to solve nonlinear differential algebraic equations describing the detailed representation of network and transient stability models of dynamic devices in a computationally efficient manner. In particular, RAPID utilizes and incorporates emerging solution techniques; a novel “parallel-in-time” (Parareal) algorithm, adaptive model reduction, and semi-analytical solution methods as well as the standard numerical solution methods. Moreover, the whole simulation process for the transmission network has been coupled with OpenDSS, a widely used open-source distribution system simulator, to enable the co-simulation of integrated transmission and distribution systems. Basic structure and features of RAPID are presented to provide an easy-to-understand guideline for the usage of the tool and illustrate its unique capabilities. This paper also presents simulation results for a number of test scenarios and demonstrates RAPID’s values for advancing power systems research in dynamic modeling and simulation techniques toward researchers as well as educators and students.

Performance evaluation of standard second-order finite volume method for DNS solution of turbulent channel flow

Performance evaluation of standard second-order finite volume method for DNS solution of turbulent channel flow

Nanoparticle Liposomes: a New Strategy in Bacterial Infections

Objective: In our study, a nanoparticle liposome molecule with patent application number TR201804452A2 was used, and the Minimum Inhibitor Concentration (MIC) was found to be 1562 ppm. According to the ASTM F 1980 standard, it has been determined that the nanoparticle liposome solution kept at 37 days and 55 oC in return for one-year stability preserves its effectiveness. Our study aimed to show that the newly developed solution maintains its effectiveness for a long time. Methods: CLSI M07-A10 (Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically. Tenth ed. Approved Standard) standard test method of the nanoparticle liposome solution developed with a technique different from the standard ozonation mechanisms, and antibacterial tests were performed by modifying the contact time and the MIC value of the solution, and its effect on time has been determined. For the stability test of the nanoparticle liposome solution, it was kept at 55 oC for 37 days in return for one-year stability according to the ASTM F 1980 standard. Results: MIC of nanoparticular ozone solution CLSI M07-A10 standard test method for S. aureus (ATCC 25923) and E. coli (ATCC 25922) strains by modifying contact time It was determined as 1.562 ppm. For S. aureus (ATCC 25923), at the end of the first hour, it was determined that the activity started at 2000 and 1750 ppm nanoparticle liposome solution concentration. For E. coli (ATCC 25922) it was determined that the activity started at the 10th minute at 2000 ppm nanoparticular ozone solution concentration. The solution was still effective at the end of one year according to the ASTM F 1980 standard in terms of effectiveness. Conclusions: As a result, the nanoparticle liposome solution, a new product, does not lose its stability and effectiveness for a long time, contrary to what is known. Although the half-life of gaseous ozone is as short as 20 minutes, the stability in the nanoparticle liposome solution has been determined as at least one year. Since nanoparticle liposome solution is a natural and slow-release product, it is thought that it can create a barrier in mucosal membranes in regions such as the nose, throat, eye and ear with solutions to be prepared in appropriate doses thus preventing bacteria from settling. Keywords: Nanoparticle liposomes, ozone, antibacterial efficiency, Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922)

Production of the chitinase by Beauveria bassiana in infecting Tribolium castaneum

Beauveria bassiana is one of the microorganisms that produce the enzyme chitinase. Chitinase has a high economic value which is widely used as a biocontrol agent because it can degrade chitin into an environmentally friendly product. The aim of the study was to investigate the production of chitinase by B. bassiana isolate in the presence of the cuticle of T. castaneum. In this study, the isolates of B. bassiana were cultured into potato dextrose agar. Further isolation, purification, and determination of the activity of chitinase. The results show that chitinase can be obtained from B. bassiana isolate derived from T. castaneum by using chitin colloidal substrate. The highest average specific activity of chitinase originating from isolated B. bassiana was 1 Unit/mg. Protein test using standard BSA solution and Lowry method obtained reading results with a spectrophotometer that was r = 0.9925.

An accurate water activity model for glycerol solutions and its implementation on moisture sorption isotherm determination

H2SO4 and glycerol solutions are two commonly used unsaturated solutions for humidity control in moisture sorption isotherm (MSI) experiments. In a previous study, we reported an accurate water activity (a w) model for H2SO4 solutions for use in MSI measurements. The current study aimed to construct a reliable a w model of glycerol solutions and apply it to MSI measurements. Our research showed that the Wilson model could accurately predict a w of glycerol solutions, with a root mean square deviation of 0.0096 a w, in the concentration range of 9.47–99.62% glycerol by mass and in the temperature range of 0–100 °C. This a w model considerably simplified the conventional glycerol solution (GSL) method. Finally, the reliability of this simplified GSL method was tested by comparing with the standard saturated salt solution method for MSI measurements of microcrystalline cellulose and apple at 25 °C. This proposed GSL method, based on the Wilson model, might be a reliable, safe, and inexpensive alternative method for MSI measurements in food areas in the future. Highlights The Wilson model can precisely predict a w of glycerol solutions. The Wilson model can remarkably simplify the known glycerol solution (GSL) method. The simplified GSL method is reliable and applicable for use in microcrystalline cellulose and apples. A working table of a w of glycerol solutions was generated for convenience of use.

An accurate water activity model for sulfuric acid solutions and its implementation on moisture sorption isotherm determination

Because of a lack of reliable models to predict the water activity (a w) of H2SO4 solutions, the standard sulfuric acid solution (SSL) method requires a periodic check and adjustment of the acid concentration to ensure that equilibrium will be reached at a predetermined a w point. To establish a reliable equation describing the a w of H2SO4 solutions, five molecular activity models, i.e. nonrandom two-liquid (NRTL), Wilson, universal quasi-chemical (UNIQUAC), modified NRTL-1 (M-NRTL 1) and modified NRTL-2 (M-NRTL 2), were introduced and compared in this study. Each of the models was applied to the 542 literature vapor-liquid equilibrium data points of H2SO4 solutions. The results showed that the NRTL model was the best with respect to its accuracy and simplicity. This NRTL model significantly simplified the implementation of the sulfuric acid solution method for MSI measurements. Excellent agreement was found between this simplified SSL method and the conventional saturated salt solution (SSS) method for MSI measurements of both microcrystalline cellulose (MCC) and apples at 25 °C. Therefore, this newly improved SSL method, based on the NRTL model, could be an inexpensive, convenient and reliable alternative to the conventional SSS method in food MSI measurements in the future. Highlights The NRTL model can accurately predict the a w of H2SO4 solutions. The NRTL model can significantly simplify the known sulfuric acid solution (SSL) method. This improved SSL method is valid and reliable for use in MCC and apples. A working table of the a w of H2SO4 solutions was developed for ease of use.

Research on an Enterprise Remanufacturing Strategy Based on Government Intervention

Due to rapid economic development and population growth, environmental pollution problems such as urban pollution and depletion of natural resources have become increasingly prominent. Municipal solid waste is part of these problems. However, waste is actually an improperly placed resource. As a part of green supply chain management, remanufacturing can turn waste products into remanufactured products for resale. Based on the development status of China’s remanufacturing industry, this paper establishes three Stackelberg game models, namely the free recycling model (model N), the government regulation model based on the reward–penalty mechanism (model G), and the government dual-intervention model (model GF). In this study, the standard solution method for the Stackelberg game method, namely the backward induction method, is applied to solve the dynamic game equilibrium. For comparison, a further numerical analysis is also carried. The research results show that: (1) in the closed-loop supply chain based on remanufacturing, the strengthening of cooperation between manufacturers and remanufacturers is beneficial in terms of maximizing supply chain profits; (2) in order to maximize social benefits, the government needs to intervene in green supply chain management; (3) government regulation is particularly important when the remanufacturing industry is in the initial stage of development; (4) government intervention needs to be based on the development level of the remanufacturing industry; (5) in order to maximize social benefits, it is recommended that the government consider the ratio between the green consumption subsidies and the taxes on new products.

New Serotoninergic Ligands Containing Indolic and Methyl Indolic Nuclei: Synthesis and In Vitro Pharmacological Evaluation.

Serotonin is an important biogenic amine and is implicated in wideranging physiological and physiopathological processes. Pharmacological manipulation of the serotoninergic system is believed to have a great therapeutic potential. In order to identify selective ligands for 5-HT1A, 5-HT2A and 5-HT2C receptors two series of 4-substituted piperazine derivatives, bearing indolic or methyl indolic nuclei, were synthesized. All the compounds, synthesized by standard solution methods, were evaluated for 5- HT1A, 5-HT2A and 5-HT2C receptors. The highest affine and selective compounds have been evaluated also on dopaminergic (D1 and D2) and adrenergic (α1A and α2A) receptors. Several of the newly synthesized molecules showed affinity in the nanomolar range for 5- HT1A, 5-HT2A and 5-HT2C receptors and moderate to no affinity for other relevant receptors (D1, D2, α1A and α2A). Compounds 7f and 10a showed a nanomolar affinity towards 5-HT1A with an in vitro pharmacologic profile compatible with antipsychotic drugs.

A crank-kinematics-based engine cylinder pressure reconstruction model

A new inverse model is proposed for reconstructing steady-state and transient engine cylinder pressure using measured crank kinematics. An adaptive nonlinear time-dependent relationship is assumed between windowed-subsections of cylinder pressure and measured crank kinematics in a time-domain format (rather than in crank-angle domain). This relationship comprises a linear sum of four separate nonlinear functions of crank jerk, acceleration, velocity and crank angle. Each of these four nonlinear functions is obtained at each time instant by fitting separate m-term Chebyshev polynomial expansions, where the total 4 m instantaneous expansion coefficients are found using a standard (overdetermined) linear least-square solution method. A convergence check on the calibration accuracy shows that this initially improves as more Chebyshev polynomial terms are used, but with further increase, the overdetermined system becomes singular. Optimal accuracy Chebyshev expansions are found to be of degree m = 4, using 90 or more cycles of engine data to fit the model. To confirm the model accuracy in predictive mode, a defined measure is used, namely the ‘ calibration peak pressure error’. This measure allows effective a priori exclusion of occasionally unacceptable predictions. The method is tested using varying speed data taken from a three-cylinder direct-injection spark ignition engine fitted with cylinder pressure sensors and a high-resolution shaft encoder. Using appropriately filtered crank kinematics (plus the ‘calibration peak pressure error’), the model produces fast and accurate predictions for previously unseen data. Peak pressure predictions are consistently within 6.5% of target, whereas locations of peak pressure are consistently within ±2.7 °CA. The computational efficiency makes it very suitable for real-time implementation.

Isogeometric analysis for 2D and 3D curl–div problems: Spectral symbols and fast iterative solvers

Alfvén-like operators are of interest in magnetohydrodynamics, which is used in plasma physics to study the macroscopic behavior of plasma. Motivated by this important and complex application, we focus on a parameter-dependent curl–div problem that can be seen as a prototype of an Alfvén-like operator, and we discretize it using isogeometric analysis based on tensor-product B-splines. The involved coefficient matrices can be very ill-conditioned, so that standard numerical solution methods perform quite poorly here. In order to overcome the difficulties caused by such ill-conditioning, a two-step strategy is proposed. First, we conduct a detailed spectral study of the coefficient matrices, highlighting the critical dependence on the different physical and approximation parameters. Second, we exploit such spectral information to design fast iterative solvers for the corresponding linear systems. For the first goal we apply the theory of (multilevel block) Toeplitz and generalized locally Toeplitz sequences, while for the second we use a combination of multigrid techniques and preconditioned Krylov solvers. Several numerical tests are provided both for the study of the spectral problem and for the solution of the corresponding linear systems.

New approaches for optimizing standby redundant systems with fuzzy lifetimes

Abstract Standby redundancy is one of the most popular ways to optimize systems reliability with several applications in modern engineering. Under real-world conditions, the system lifetime can be modeled as a fuzzy interval due to parameter uncertainty and data inaccuracy. In this paper, several fuzzy standby redundancy optimization models are proposed utilizing three distinct types of decision criteria, namely as the expected value model, the chance-constrained and the dependent-chance programming. Thereafter, two solution processes are proposed. The first one utilizes a novel algorithm with lower computational complexity for a specific fuzzy objective which is embedded into intelligent optimization algorithms to derive a hybrid algorithm. While the other approach relies upon the transformation of the fuzzy model into its deterministic counterpart employing a family of fuzzy operational laws, then the solution derives in a straightforward manner using classical optimization algorithms or some well-developed software packages. Finally, several diverse numerical examples are considered for demonstrating the superiority of our treatment. It is shown that the herein developed solution approaches for the fuzzy standby redundancy optimization problems exhibit higher efficiency and satisfactory accuracy as compared with standard solution methods.

Systematic derivation of a surface polarisation model for planar perovskite solar cells

Increasing evidence suggests that the presence of mobile ions in perovskite solar cells (PSCs) can cause a current–voltage curve hysteresis. Steady state and transient current–voltage characteristics of a planar metal halide CH3NH3PbI3PSC are analysed with a drift-diffusion model that accounts for both charge transport and ion vacancy motion. The high ion vacancy density within the perovskite layer gives rise to narrow Debye layers (typical width ~2 nm), adjacent to the interfaces with the transport layers, over which large drops in the electric potential occur and in which significant charge is stored. Large disparities between (I) the width of the Debye layers and that of the perovskite layer (~600 nm) and (II) the ion vacancy density and the charge carrier densities motivate an asymptotic approach to solving the model, while the stiffness of the equations renders standard solution methods unreliable. We derive a simplifiedsurface polarisationmodel in which the slow ion dynamics are replaced by interfacial (non-linear) capacitances at the perovskite interfaces. Favourable comparison is made between the results of the asymptotic approach and numerical solutions for a realistic cell over a wide range of operating conditions of practical interest.