General Optimization Criterion Research Articles

Topology optimization of non-linear electromagnetic actuator based on Reluctance Network Analysis

Topology Optimization (TO) enables unrestricted exploration within a design domain and is typically based on a spatial discretization that is also used as the mesh for simulation. In this article, we propose to use for the simulation a mesh-based equivalent circuit method termed the Reluctance Network Analysis (RNA), with nonlinear magnetic properties of the material. The simulation tool is then used in a topology optimization process solved with generalized optimality criteria (GOC) method. During the optimization, the sensitivity matrix is needed, and we describe here how to derive the matrix in the case of a nonlinear RNA using Adjoint Variable Method (AVM). Finally, we implemented this topology optimization through a case study of an electromagnetic actuator.

Magneto-Mechanical Topology Optimization With Generalized Optimality Criteria

Magneto-Mechanical Topology Optimization With Generalized Optimality Criteria

Performance Evaluation of Photonics-Based Coherent MIMO Radar Systems for Maritime Surveillance

Multiple-input multiple-output (MIMO) radars offer significant advantages over conventional standalone radars in terms of target detection and localization capabilities. However, to fully exploit their potential, such systems require excellent time and phase synchronization among the central unit and the radar heads. Only recently, thanks to microwave photonics (MWP) techniques, it has been possible to develop the first coherent MIMO radar demonstrators. In this paper, a simulation tool in MATLAB programming language is proposed to model coherent MIMO radars based on MWP techniques in maritime surveillance applications. Moreover, a novel approach for estimating the radar cross section of extended maritime targets is presented. The system performance in co-located and distributed MIMO configuration, as well as in single- and multi-band operations, is evaluated by means of relevant key performance indicators (KPIs). Simulations are carried out in two close-to-reality scenarios. In the first, a co-located MIMO radar is mounted on top of a patrolling vessel. In the second, a distributed MIMO radar is deployed inside a port. The proposed KPIs are analyzed in terms of both geometric and frequency diversities of the system, laying the foundations for general system optimization criteria valid in any given surveillance application.

Some issues of multi-criteria optimization of parameters of complex systems

Objective. The purpose of the study is to substantiate the design criteria for optimality, taking into account the multi-criteria purpose and functioning of the object.Method. The study was carried out on the basis of multicriteria optimization methods, the hierarchy analysis method, the convolution method, and heuristic methods.Result. The paper describes general problems of multicriteria optimization of mechanical systems. The importance of the problem of substantiating the design criteria for optimality, taking into account the multi-criteria purpose and functioning of the object, and introducing quantitatively measurable goals from a variety of alternative options is indicated. It is noted that the choice and formation of a generalized optimality criterion is the most responsible in solving optimization problems. The need to ensure the correctness of the application of one or another convolution method is indicated. Various approaches to the formation of a generalized optimality criterion are analyzed. Their features, advantages and disadvantages are given. The possibility of correcting parametric constraints in problems of improving optimal solutions is pointed out.Conclusion. When solving multi-criteria problems, it is necessary to pay great attention to both the formulation of the problem and the choice of a system of criteria and the implemented method for solving the problem.

Optimally adaptive thermal reproducing infrared systems for early fire detection

The article is devoted to the optimization of adaptive thermal reproducing systems in the infrared range. The possibility of introducing a general optimization criterion by calculating the geometric mean of two equivalent temperature indicators of high frequency temporal noise is shown. A problem of variational optimization has been formulated, the essence of which is to calculate such a relationship between the integration time and atmospheric transmission at which the objective functional, under some restrictive condition imposed on this function, reaches a minimum, which is equivalent to the minimum difference between the indicated equivalent temperatures.

Platinum(IV) compounds as potential drugs: a quantitative structure-activity relationship study.

Machine learning methods, coupled with a tremendous increase in computer power in recent years, are promising tools in modern drug design and drug repurposing. Machine learning predictive models, publicly available at chemosophia.com, were used to predict the bioactivity of recently synthesized platinum(IV) complexes against different kinds of diseases and medical conditions. Two novel QSAR models based on the BiS algorithm are developed and validated, capable to predict activities against the SARS-CoV virus and its RNA dependent RNA polymerase. The internal predictive power of the QSAR models was tested by 10-fold cross-validation, giving cross-R2 from 0.863 to 0.903. 38 different activities, ranging from antioxidant, antibacterial, and antiviral activities, to potential anti-inflammatory, anti-arrhythmic and anti-malarial activity were predicted for a series of eighteen platinum(IV) complexes. Complexes 1, 3 and 13 have high generalized optimality criteria and are predicted as potential SARS-CoV RNA dependent RNA polymerase inhibitors.

Stochastic Safest and Shortest Path Problems

Optimal solutions to Stochastic Shortest Path Problems (SSPs) usually require that there exists at least one policy that reaches the goal with probability 1 from the initial state. This condition is very strong and prevents from solving many interesting problems, for instance where all possible policies reach some dead-end states with a positive probability. We introduce a more general and richer dual optimization criterion, which minimizes the average (undiscounted) cost of only paths leading to the goal among all policies that maximize the probability to reach the goal. We present policy update equations in the form of dynamic programming for this new dual criterion, which are different from the standard Bellman equations, but produce the same solution if there exists one policy leading to the goal with probability 1 from the initial state. We demonstrate that our equations converge in infinite horizon without any condition on the structure of the problem or on its policies, which actually extends the class of SSPs that can be solved. We experimentally show that our dual criterion provides well-founded solutions to SSPs that can not be solved by the standard criterion, and that using a discount factor with the latter certainly provides solution policies but which are not optimal considering our well-founded criterion.

A unified energy-optimality criterion predicts human navigation paths and speeds

Navigating our physical environment requires changing directions and turning. Despite its ecological importance, we do not have a unified theoretical account of non-straight-line human movement. Here, we present a unified optimality criterion that predicts disparate non-straight-line walking phenomena, with straight-line walking as a special case. We first characterized the metabolic cost of turning, deriving the cost landscape as a function of turning radius and rate. We then generalized this cost landscape to arbitrarily complex trajectories, allowing the velocity direction to deviate from body orientation (holonomic walking). We used this generalized optimality criterion to mathematically predict movement patterns in multiple contexts of varying complexity: walking on prescribed paths, turning in place, navigating an angled corridor, navigating freely with end-point constraints, walking through doors, and navigating around obstacles. In these tasks, humans moved at speeds and paths predicted by our optimality criterion, slowing down to turn and never using sharp turns. We show that the shortest path between two points is, counterintuitively, often not energy-optimal, and, indeed, humans do not use the shortest path in such cases. Thus, we have obtained a unified theoretical account that predicts human walking paths and speeds in diverse contexts. Our model focuses on walking in healthy adults; future work could generalize this model to other human populations, other animals, and other locomotor tasks.

Generalized optimality criteria of energy-efficient composites

The article discusses generalized optimality criteria of energy-efficient materials. The task of choosing an optimality criteria of a composite is considered as a step-by-step, hierarchical transition from individual criteria of the first level - operational characteristics to combined ones, related to subsequent levels and then to the general one. At each hierarchical level, the criteria become more complicated as it considers the criteria of the previous levels. The criteria constructed in this way are classified into structural, relative and conditional. It is shown that the softening coefficient and the water resistance index correspond to the criteria of the second and third levels, respectively. Some of the new combined criteria, having the character of efficiency were reviewed. As an example of a combined criteria, the criterion of the effectiveness of the realization of the strength-thermal conductivity ratio was considered. Examples of its use for evaluating and comparing the effectiveness of materials with significantly different properties and areas of use were given. It is shown that the efficiency criterion has similar values for materials with equal properties combination. On the basis of the proposed criterion, the problem of optimizing the efficiency of the plaster material is considered. As a result of numerical optimization, compositions with the maximum efficiency of the considered type were obtained. The possibility of further application of this and other combined optimality criteria in the problems of quality assessment and optimization of composite materials was shown.

Generalized Optimality Criteria Method for Topology Optimization

In this article, a generalized optimality criteria method is proposed for topology optimization with arbitrary objective function and multiple inequality constraints. This algorithm uses sensitivity information to update both the Lagrange multipliers and design variables. Different from the conventional optimality criteria method, the proposed method does not satisfy constraints at every iteration. Rather, it improves the Lagrange multipliers and design variables such that the optimality criteria are satisfied upon convergence. The main advantages of the proposed method are its capability of handling multiple constraints and computational efficiency. In numerical examples, the proposed method was found to be more than 100 times faster than the optimality criteria method and more than 1000 times faster than the method of moving asymptotes.

The Dynamic Model of Macroregion Transport Activity Development Based on a Generalized Optimization Criterion

The article is devoted to the research of the development of transport activities of the Ural Federal District. This macroregion of Russia acquires the opportunity to use the specifics of the modern period of development on the Eurasian continent in the context of international economic integration and the involvement of countries in the processes of international unification of economies. The possibility of using a generalized indicator as a measure of dynamic development concerning the transport system of a macroregion is being investigated. The dynamics of changes in the generalized criterion for optimizing the transport activities of the macroregion is calculated. The dynamic model of the development of the transport activity of the macroregion based on the generalized optimization criterion determines the result of the activity of the regional transportation system in the process of its implementation. The values of the optimization criterion deviate from the optimum significantly over the period under research. The suboptimal development of the transport system of the macroregion is observed.

Optimization of technological factors of magneticelectric strengthening

In order to determine the optimal values of technological factors for electromagnetic hardening process (EMHP), an experimental study of the process of applying ferromagnetic Fe – 2 % V powder coating on 30ХГС (GOST 4543- 71) steel parts was conducted. The process productivity and coating continuity were selected as the target parameters for the EMHP optimization. By applying the experimental design method, based on 5-factor central composite rotatable uniform plan, we have created stochastic models, expressed in regression functions of the second order. It has been determined that the magnetic induction value in the working gap is the most significant technological factor, affecting both target parameters. With the increasing induction magnitude the process productivity and the coating continuity increase non-linearly until the maximum limit value, which was attributed to the forming of current-conductive chains in the working gap, that have varying electrical conductivity and different directions relative to the lines of magnetic field forces. In order to determine the optimal EMHP mode we have solved the problems of finding maximums for greatest productivity and coating continuity within the constraints of the studied factor range. The discovered EMHP-modes, optimal for each separate parameter, coincide only in the value of the magnetic induction and the discharge density. The optimal values for the other control factors belong to different areas of factor range for different optimization parameters. To determine the EMHP modes, balanced against the both parameters, the problem of multicriteria optimization was solved. The obtained solution reveals that the density of discharge currents produces the biggest impact on the process productivity and the coating continuity within the balanced modes. At the same time the high continuity of the coating is achieved by the supplementing increase of peripheral speed of the processed workpiece, which leads to evener distribution of the intensively supplied mass of the ferromagnetic powder on the treated surface. The recommended technological modes of EMHP have been determined, based on the generalized optimality criteria.

Development of creating computer programs method for multivariate optimization of functional meat product recipes

The article presents the results of development and testing of new computer program for calculating functional meat products based on Microsoft Office Excel 2010. The paper describes methodology of its creation, including method and formulas of calculation, presentation type of input data and calculation results, as well as possibility of increasing accuracy and efficiency of optimization when using programs of this type. The necessity of developing software for optimizing functional food products, based on a full search algorithm, is substantiated. The ways of using the program and ways of its further development are presented. The key advantages and disadvantages of using the created computer program are identified. The computer program at the end of its work provides the user a list of formulations optimized according to the general optimality criterion, which is an undeniable advantage. This is important because it is very difficult to predict organoleptic indicators at the current level of technological development. It was revealed that in the current form, amount of computing a computer program directly depends on the size of database used. An idea of identifying a logical function that organoleptic properties with respect to parameters of raw materials in a recipe is proposed.

Determining the factors that affect the quality of test prints at flexographic printing

The intensive use of flexographic printing for packaging decoration and the increased consumer demands for it require an in-depth study of the factors that influence the prints’ quality. In this paper, we examined the test prints obtained at a flexographic proofer. Images on cardboard were printed by the environmentally friendly inks made by a Ukrainian manufacturer. The effect of the cardboard surface layer on the microgeometry of the prints created by cyan, yellow, black, and magenta inks has been shown. It has been established that the roughness parameter Ra for a two-layer coated cardboard is reduced by 3 times as compared to the uncoated cardboard. The photographs of the microstructure of the prints’ surface, their profile demonstrate a significant effect of the chalked coating on the image quality. It has been confirmed that the ink layer smooths out the micro-roughness of the print surface. However, when printed on the uncoated cardboard, the ink particles penetrate deeper into the structure and do not completely smooth out its micro-roughness. If the size of the printing element is smaller than the size of the cell on a raster roller, it falls into this cell and the ink is applied beyond the boundaries of the image. As a result, a spot of an arbitrary shape is formed on the print instead of a raster dot of a certain size, that is, the so-called "inverse tone transfer" occurs. We have measured the densitometric indicators of prints (optical density, gray balance), which significantly affect the quality of the product. Based on a Harrington's desirability function, the maximum permissible values of optical density, evenness of printing, contrast, dot gain of raster elements, and trapping, have been calculated. According to the generalized optimization criterion, a comprehensive index of the prints’ quality has been determined, which could ensure the predicted quality of a would-be run of the printed products, and would make it possible to adjust the printing process if necessary

Problems of energy resources allocation at decision-making stages in architecture and urban planning activities

All the levels of architecture and urban planning activities (management, designing, execution of construction works) bring up various questions of the optimal distribution of energy resources. This paper shows that the energy resources allocation is connected with different classes of tasks in optimal decisions making and belongs to mathematical programming problems. Optimization tasks at the stages of scientific research, substantiation and version design should be performed on the basis of dynamic system models of the type «population ↔ environment». The article justifies the need for deductive approach and system methods and evaluation criteria of energy resources distribution at the stages of design and quality evaluation of architectural objects. It is demonstrated that in architectural theory and practice, for the purpose of quantitative measurement of the quality of architectural and construction activity products, the scientific research of the new area – architectural metrology – is needed. The energy interpretation of the general optimality criterion of integral architectural objects as systems, functioning in accordance with general system principles, is discussed.

Study of the influence of oscillatory processes in a mobile vehicle on the running smoothness characteristics

The issue of optimizing the dynamic characteristics of a mobile vehicle depending on the operating conditions is considered. The optimization problems were solved taking into account the random nature of dynamic loads. The task of transforming the input effect on the elements of the mobile machine was solved in a deterministic aspect using integrated criteria. As a measure of the accuracy of the introduced criteria, the standard deviation was used. The minimum values of vertical reactions on the header shoes were determined by the dispersion of its oscillations, taking into account the spectral density of the irregularities of the agricultural background. It was found that the frequency characteristics of the header shoes also depend on the vertical and longitudinal-angular vibrations of the combine separator. Optimality criteria are presented for assessing the dispersion of vibrational parameters of vehicles from external influences. The general optimization criterion was determined based on the independence of the objective functions and the maximum quantile of the normal distribution, which allowed, in a probabilistic aspect, to evaluate the optimization efficiency for agricultural machinery with a wide range of applications. The local optimum was determined by the expression of objective functions in terms of elementary functions, taking into account statistical parameters and the nature of the distribution of a random variable. The optimal transfer function was determined based on the minimum value of the standard deviation of the objective function taking into account the Fourier variables. The determination of the local optimum was carried out graphoanalytically by the objective function of smoothness and by the probabilistic criterion. The optimal value of the relative attenuation coefficient of vertical oscillations of the separator body was determined, the reason for its minimization and the probability of exceeding the permissible vibration level were established. A method for determining the transfer function to predict the smoothness of the combine is presented. The possibilities of the proposed optimization method are estimated.

Method of Generalized Evaluation in the Selecting Factors and Levels of Variation in the Multifactorial Study of Sowing Machines

The results of studying complex objects can be presented as a problem with several outputs, and this will require a separate mathematical model for each result. If we use a generalized optimization criterion (super criterion), for example, in the form of the Harrington desirability function, one model will suffice. The authors have drawn an example of applying this methodology to determine the factors influencing the seeding process performed with an experimental seeder.(Research purpose) To show general recommendations for improving the process of planning and organization of scientific experiments in the field of agricultural engineering.(Materials and methods) The authors were guided by the idea of converting the natural values of particular criteria (or characteristics) into a dimensionless scale of desirability with subsequent assessment of the level of preference of a set of factors and their levels of variation in a multifactorial experiment. The object of research was represented by a sowing unit used for combined seeding of two crops. (Results and discussion) The study has established the following levels of desirability of natural output values (combinations of the variation levels of experimental factors): "very good", "good", "satisfactory", "bad", and "very bad". The rate of influence of these factors on corn seed sowing with an experimental seeder was obtained by applying a priori ranking technique. An acceptable set of values (a combination of optimal and maximum values) from the range of factors variation was revealed, which provides for more qualitative choice of the main factors influencing the optimization parameter. The authors have demonstrated the operation of the patented software to calculate data according to the Box-Behnken plan, which allows to obtain sufficient information about the response surface of the process in the experiment center selected as the expected optimum. (Conclusions) The paper presents the way of preparing for an experiment and subsequent processing of the results of complex studies using the super criterion. The necessity for digitalizing the process of planning and organization of scientific experiments has been emphasized.

Augmented Slepians: Bandlimited Functions That Counterbalance Energy in Selected Intervals

Slepian functions provide a solution to the optimization problem of joint time-frequency localization. Here, this concept is extended by using a generalized optimization criterion that favors energy concentration in one interval while penalizing energy in another interval, leading to the "augmented" Slepian functions. Mathematical foundations together with examples are presented in order to illustrate the most interesting properties that these generalized Slepian functions show. Also the relevance of this novel energy-concentration criterion is discussed along with some of its applications.

Exact Optimization of a Three-Element Dynamic Vibration Absorber: Minimization of the Maximum Amplitude Magnification Factor

In this study, the maximum amplitude magnification factor for a linear system equipped with a three-element dynamic vibration absorber (DVA) is exactly minimized for a given mass ratio using a numerical approach. The frequency response curve is assumed to have two resonance peaks, and the parameters for the two springs and one viscous damper in the DVA are optimized by minimizing the resonance amplitudes. The three-element model is known to represent the dynamic characteristics of air-damped DVAs. A generalized optimality criteria approach is developed and adopted for the derivation of the simultaneous equations for this design problem. The solution of the simultaneous equations precisely equalizes the heights of the two peaks in the resonance curve and achieves a minimum amplitude magnification factor. The simultaneous equations are solvable using the standard built-in functions of numerical computing software. The performance improvement of the three-element DVA compared to the standard Voigt type is evaluated based on the equivalent mass ratios. This performance evaluation is highly accurate and reliable because of the precise formulation of the optimization problem. Thus, the advantages of the three-element type DVA have been made clearer.

ОПТИМАЛЬНОЕ УПРАВЛЕНИЕ ПРОЦЕССОМ КАТАЛИТИЧЕСКОГО РИФОРМИНГА БЕНЗИНОВЫХ ФРАКЦИЙ

The current task is to develop an optimal control system for the catalytic reforming process, which ensures the achievement of optimal ratios of the octane number of gasoline and production costs. The formulation of the problem of optimal control of the catalytic reforming process is performed, which is distinguished by using the generalized optimality criterion as the target functional. A hybrid mathematical model of the catalytic reforming process has been developed, which takes into account the influence of parameters characterizing production costs and the octane number of gasoline on the efficiency of the process and makes it possible to calculate the values of the generalized optimality criterion depending on the values of the input variables of the process. Based on LP-35-11/1000 model for installation, there have been obtained the maximum annual costs of 4.05 billion RUB and the minimum octane number of gasoline 92.83. A multicriterial choice of the temperature control system at the exit from the furnace is fulfilled. The algorithm for determining the settings of the temperature regulator at the exit from the furnace in various modes of the catalytic reforming process is synthesized. The method of optimal control of the catalytic reforming process is developed, which is characterized by the consideration of expert information in the formalization of fuzzy goals and constraints in process control and allows to calculate optimal control actions, according to the Bellman-Zade scheme depending on the values of the input variables of the process. Based on this technique, a vector of controls corresponding to the minimum of the generalized optimality criterion I = 0.964 is determined. The search of Pareto-optimal solutions for controlling the catalytic reforming process was carried out. Positive effects were obtained using the developed system of optimal control of the catalytic reforming process: decrease in average costs by 0.33 million RUB; increase in the average octane number by 0.53; decrease in the average value of the generalized optimality criterion by 0.025.