scholarly journals SEARCH FOR THE OPTIMAL VALUE OF THE INITIAL CONCENTRATION OF DIISOBUTYLALUMINUM HYDRIDE FOR THE REGULATION OF THE POLYISOPRENE MOLECULAR MASS ON A NEODYMIUM-CONTAINING CATALYTIC SYSTEM

2020 ◽  
pp. 52-64
Author(s):  
Евгения Викторовна Антипина ◽  
Эльдар Наилевич Мифтахов ◽  
Светлана Анатольевна Мустафина
Keyword(s):  
Differential Equations ◽  
Method Of Moments ◽  
Optimization Problem ◽  
Optimality Criterion ◽  
Catalyst System ◽  
Diisobutylaluminum Hydride ◽  
Initial Concentration ◽  
Optimal Value ◽  
Optimal Values ◽  
Kinetic Diagram

Статья посвящена нахождению оптимального значения начальной концентрации диизобутилалюминийгидрида для полимеризации изопрена на неодимсодержащей каталитической системе. Для исследования закономерностей протекания процесса полимеризации изопрена построена кинетическая модель, то есть система обыкновенных дифференциальных уравнений, выражающих динамику концентраций частиц, участвующих в процессе. Система дифференциальных уравнений высокой размерности сведена к конечному виду путем применения метода моментов. Приведена в общем виде постановка задачи поиска оптимальных значений начальных концентраций веществ химического процесса. В качестве метода решения поставленной оптимизационной задачи в работе использованы эволюционные методы, в основе одного из которых лежит генетический алгоритм. Проведен вычислительный эксперимент для процесса полимеризации изопрена по поиску оптимального значения начальной концентрации диизобутилалюминийгидрида с целью регулирования молекулярной массы полиизопрена. Показано, что рассчитанное значение концентрации диизобутилалюминийгидрида обеспечивает достижение заданного критерия оптимальности. The article is devoted to finding the optimal value of the initial concentration of diisobutylaluminum hydride for the polymerization of isoprene on a neodymium-containing catalyst system. The authors present a kinetic diagram of the polymerization of isoprene on a neodymium-containing catalyst system using two types of organoaluminum compounds: triisobutylaluminum and diisobutylaluminum hydride. To study the patterns of the polymerization of isoprene, a kinetic model is constructed, that is, a system of ordinary differential equations expressing the dynamics of the concentration of particles involved in the process. The system of high-dimensional differential equations is reduced to the final form by applying the method of moments. The general statement of the problem of finding the optimal values of the initial concentrations of the substances of the chemical process is given. As a method for solving the optimization problem posed, evolutionary methods are used in the work, one of which is based on a genetic algorithm. A computational experiment was conducted for the polymerization of isoprene to find the optimal value of the initial concentration of diisobutylaluminum hydride in order to control the molecular weight of polyisoprene. It is shown that the calculated value of the concentration of diisobutylaluminium hydride provides achievement of the specified optimality criterion.

FORMULATION AND SOLUTION OF OPTIMIZATION PROBLEM REDUNDANCY SYSTEM COMPRISING SITUATION CENTER

2019 ◽  
pp. 44-50
Author(s):  
A.V. Alekseev
Keyword(s):  
Analytical Model ◽  
Quality Indicators ◽  
Significant Influence ◽  
Optimization Problem ◽  
Sampling Theorem ◽  
Sampling Frequency ◽  
Generalized Sampling ◽  
Optimal Value ◽  
Situation Center ◽  
Situation Centers

The analysis of the concept, properties and features of heterogeneous redundancy in modern complex ergatic systems, including those included in the situation centers (SC). On the basis of the qualimetric paradigm, the generalized analytical model of quality and optimization of quality by private, group, summary and aggregated quality indicators is justified. Practical ways of realization of the model and methods of optimization of the objects which are a part of SC and them as a whole at the expense of reduction of structural, functional and other types of redundancy under the obligatory condition of non-reduction of the required value of quality are given. On the example of the generalized sampling theorem when choosing the optimal value of the sampling frequency of the real bandpass signal, the criticality and significant influence on the redundancy of data in their further processing in the SC is shown.

scholarly journals Discretization and machine learning approximation of BSDEs with a constraint on the Gains-process

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Idris Kharroubi ◽  
Thomas Lim ◽  
Xavier Warin
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Neural Networks ◽  
Differential Equations ◽  
Numerical Experiments ◽  
Optimization Problem ◽  
Learning Approach ◽  
The Neural Network ◽  
Machine Learning Approach ◽  
Mesh Grid

AbstractWe study the approximation of backward stochastic differential equations (BSDEs for short) with a constraint on the gains process. We first discretize the constraint by applying a so-called facelift operator at times of a grid. We show that this discretely constrained BSDE converges to the continuously constrained one as the mesh grid converges to zero. We then focus on the approximation of the discretely constrained BSDE. For that we adopt a machine learning approach. We show that the facelift can be approximated by an optimization problem over a class of neural networks under constraints on the neural network and its derivative. We then derive an algorithm converging to the discretely constrained BSDE as the number of neurons goes to infinity. We end by numerical experiments.

scholarly journals A RED modified weighted moving average for soft real-time application

2014 ◽  
Vol 24 (3) ◽  
pp. 697-707 ◽  
Author(s):  
Joanna Domanśka ◽  
Adam Domański ◽  
Dariusz R. Augustyn ◽  
Jerzy Klamka
Keyword(s):  
Real Time ◽  
Optimization Problem ◽  
Optimality Criterion ◽  
Task Force ◽  
Moving Average ◽  
Timing Constraints ◽  
Real Time Traffic ◽  
Real Time Application ◽  
Weighted Moving Average

Abstract The popularity of TCP/IP has resulted in an increase in usage of best-effort networks for real-time communication. Much effort has been spent to ensure quality of service for soft real-time traffic over IP networks. The Internet Engineering Task Force has proposed some architecture components, such as Active Queue Management (AQM). The paper investigates the influence of the weighted moving average on packet waiting time reduction for an AQM mechanism: the RED algorithm. The proposed method for computing the average queue length is based on a difference equation (a recursive equation). Depending on a particular optimality criterion, proper parameters of the modified weighted moving average function can be chosen. This change will allow reducing the number of violations of timing constraints and better use of this mechanism for soft real-time transmissions. The optimization problem is solved through simulations performed in OMNeT++ and later verified experimentally on a Linux implementation

scholarly journals Modeling of transport and technological processes of cultivation and harvesting agricultural crops

2021 ◽  
Vol 285 ◽  
pp. 07027
Author(s):  
Nikolay Maystrenko ◽  
Alexandr Levshin ◽  
Dmitriy Khort ◽  
Alexey Kutyrev
Keyword(s):  
Optimality Criterion ◽  
Practical Interest ◽  
Economic Conditions ◽  
Agricultural Crops ◽  
Agricultural Work ◽  
Technological Processes ◽  
Shift Performance ◽  
Wide Range ◽  
Optimal Values ◽  
Technological Means

The productivity of technological processes in agriculture is determined by the set of transport and technological means used. The article describes the models for the unification of shift performance, taking into account a wide range of agricultural cargoes and a large number of works on their movement in the process of cultivation and harvesting of agricultural crops. A step-by-step modeling of scenarios for the use of transport and technological means was carried out on the basis of the optimality criterion and forecasting the period of agricultural work. They confirmed that the objective function is of theoretical and practical interest, as it helps to determine the optimal values of the power of technical means, depending on the combination of production conditions. The numerical value of power obtained by calculation can serve as a guide for manufacturers of agricultural machinery in the development of promising vehicles for a specific consumer, depending on the availability of resources and production and economic conditions.

scholarly journals Structural reliability under uncertainty in moments: distributionally-robust reliability-based design optimization

2021 ◽  
Author(s):  
Yoshihiro Kanno
Keyword(s):  
Design Optimization ◽  
Optimization Problem ◽  
Structural Reliability ◽  
Reliability Based Design Optimization ◽  
Input Distribution ◽  
Reliability Based Design ◽  
Optimal Value ◽  
Reliability Constraint ◽  
Distributionally Robust ◽  
Robust Reliability

AbstractThis study considers structural optimization under a reliability constraint, in which the input distribution is only partially known. Specifically, when it is only known that the expected value vector and the variance-covariance matrix of the input distribution belong to a given convex set, it is required that the failure probability of a structure should be no greater than a specified target value for any realization of the input distribution. We demonstrate that this distributionally-robust reliability constraint can be reduced equivalently to deterministic constraints. By using this reduction, we can handle a reliability-based design optimization problem under the distributionally-robust reliability constraint within the framework of deterministic optimization; in particular, nonlinear semidefinite programming. Two numerical examples are solved to demonstrate the relation between the optimal value and either the target reliability or the uncertainty magnitude.

PRODUCTIVE LONGEVITY OF COWS: INFLUENCE OF METABOLITES OF METABOLISM ON REPRODUCTIVE FUNCTION

2020 ◽  
pp. 19-22
Author(s):  
Е.О. КРУПИН ◽  
Ш.К. ШАКИРОВ
Keyword(s):  
Life Expectancy ◽  
Ketone Bodies ◽  
Reproductive Function ◽  
Lactation Period ◽  
Protein Ratio ◽  
Protein Mass ◽  
Service Period ◽  
Optimal Value ◽  
Mass Fractions ◽  
Optimal Values

Дана оценка причин выбраковки дойных коров из стад, определена продолжительность их жизни, установлены соотношения МДЖ и МДБ в молоке коров и на основании этого выявлены взаимосвязи с содержанием кетоновых тел в молоке и некоторыми показателями воспроизводства. Наиболее часто животные выбывают из стада в связи с гинекологическими заболеваниями — 45,9%, за первые 100 дней лактации — 42,05%. Продолжительность жизни коров, выбракованных вследствие инфекционных и инвазионных болезней, является минимальной и составляет 4 года, у коров, выбывших по причине внутренних незаразных и хирургических болезней, на 15 и 20% больше. При соотношении массовых долей жира и белка (СЖБ) 1,10 и менее содержание бета-гидроксимасляной кислоты (БОМК) в молоке достоверно (на 80%, P<0,01) превышает данный показатель у животных с оптимальными значениями СЖБ. У коров с оптимальным СЖБ уровень ацетона в молоке был выше порогового на 28,57%, а у животных с низкими значениями СЖБ достоверное превышение составило 42,85% (P<0,05). Особи с СЖБ ниже оптимальных значений в первые 100 дней характеризовались более длительным периодом лактации в целом на 8,57%, в то время как у животных с оптимальным СЖБ ее продолжительность приближалась к стандартной и составила 308,13 дня (P<0,001), межотельный период был на 5,39% менее продолжительным (P<0,001). При оптимальных значениях СЖБ длительность сервис-периода равнялась 112,91 дня, что на 14,73% короче (P<0,001) продолжительности сервис-периода у животных с низкими значениями СЖБ. The analysis of the reasons for leaving dairy cows from the herd was carried out. The life expectancy of cows has been determined. The ratios of fat to protein mass fractions in cow's milk have been established. The relationship between the content of ketone bodies in milk and reproductive indicators in animals was revealed. Most often, animals leave the herd due to gynecological diseases (45.9%), and in the first 100 days of lactation (42.05%). The life expectancy of cows culled due to infectious and invasive diseases is minimal and amounts to 4 years. For cows abandoned due to internal non-communicable and surgical diseases, life expectancy was 15 and 20% longer. When the ratio of mass fractions of fat to protein was 1.10 or less, the content of beta-hydroxybutyric acid in milk significantly (by 80%, P<0.01) exceeded this indicator in animals with optimal values of the ratio of fat to protein. In cows with an optimal fat to protein ratio, the acetone level in milk was 28.57% above normal. In animals with a low value of the ratio of fat to protein, the significant excess was 42.85% (P<0.05). Animals with a ratio of fat to protein below the optimal value were characterized by a longer lactation period in general by 8.57%. In animals with an optimal fat-to-protein ratio, the duration of lactation approached the standard one and was 308.13 days (P<0.001), and the interbody period was 5.39% shorter (P<0.001). With optimal values of the fat-to-protein ratio, the duration of the service period was 112.91 days, which is 14.73% shorter (P<0.001) than the duration of the service period in animals with low values of the fat-to-protein ratio.

Network Centric Warfare as Complex Optimization: An Evolutionary Approach

2016 ◽  
Vol 15 (2) ◽  
pp. 93-105
Author(s):  
Zoltán Jobbágy
Keyword(s):  
Optimization Problem ◽  
Fitness Landscape ◽  
Balance Theory ◽  
Military Operations ◽  
Shifting Balance Theory ◽  
Number Of Genes ◽  
Shifting Balance ◽  
Complex Optimization ◽  
Optimal Values ◽  
Different Characteristics

Military operations are very complex undertakings. However, complexity is not a feature unique to military operations. When biologists wanted to understand the properties of gene mutation they also faced complexity. Confronted by a large number of genes featuring different characteristics, a difficult-to-decode interac- tion among those genes, and an environment that could not be excluded as a factor, Sewell Wright introduced the shifting balance theory, also known as the theory of the fitness landscape. The theory allows complexity to be seen as a process that rests on adaptation and mutation. These two processes are also central to military operations as it is imperative to offset the changing conditions coming both from the environment and the interaction with the enemy. In the article the author uses Wright’s theory to help see military operations as a complex optimization problem that includes approximations and estimations regarding optimal values.

A variational approach to nonlinear stochastic differential equations with linear multiplicative noise

2019 ◽  
Vol 25 ◽  
pp. 71
Author(s):  
Viorel Barbu
Keyword(s):  
Differential Equations ◽  
Stochastic Differential Equations ◽  
Parabolic Equations ◽  
Optimization Problem ◽  
Multiplicative Noise ◽  
Generalized Solution ◽  
Convex Optimization Problem ◽  
Nonlinear Stochastic Differential Equations ◽  
Infinite Dimensional ◽  
Wiener Processes

One introduces a new concept of generalized solution for nonlinear infinite dimensional stochastic differential equations of subgradient type driven by linear multiplicative Wiener processes. This is defined as solution of a stochastic convex optimization problem derived from the Brezis-Ekeland variational principle. Under specific conditions on nonlinearity, one proves the existence and uniqueness of a variational solution which is also a strong solution in some significant situations. Applications to the existence of stochastic total variational flow and to stochastic parabolic equations with mild nonlinearity are given.

scholarly journals A NUMERICAL STUDY OF IMPROVED QUARK ACTIONS ON ANISOTROPIC LATTICES

2006 ◽  
Vol 21 (05) ◽  
pp. 1015-1032 ◽  
Author(s):  
SHIQUAN SU ◽  
LIUMING LIU ◽  
XIN LI ◽  
CHUAN LIU
Keyword(s):  
Quark Mass ◽  
Numerical Study ◽  
Charm Quark ◽  
Gauge Coupling ◽  
Speed Of Light ◽  
Lattice Action ◽  
Charm Quark Mass ◽  
Anisotropic Lattices ◽  
Optimal Value ◽  
Optimal Values

Tadpole improved Wilson quark actions with clover terms on anisotropic lattices are studied numerically. Using asymmetric lattice volumes, the pseudoscalar meson dispersion relations are measured for eight lowest lattice momentum modes with quark mass values ranging from the strange to the charm quark with various values of the gauge coupling β and three different values of the bare speed of light parameter ν. These results can be utilized to extrapolate or interpolate to obtain the optimal value for the bare speed of light parameter ν opt (m) at a given gauge coupling for all bare quark mass values m. In particular, the optimal values of ν at the physical strange and charm quark mass are given for various gauge couplings. The lattice action with these optimized parameters can then be used to study physical properties of hadrons involving either light or heavy quarks.

scholarly journals Optimal Design of Dynamic Default Risk Measures

2012 ◽  
Vol 49 (4) ◽  
pp. 967-977 ◽  
Author(s):  
Leo Shen ◽  
Robert Elliott
Keyword(s):  
Optimal Design ◽  
Differential Equations ◽  
Stochastic Differential Equations ◽  
Continuous Time ◽  
Default Risk ◽  
Optimization Problem ◽  
Risk Measures ◽  
Risk Measure ◽  
Jump Process ◽  
Entropic Risk Measure

We consider the question of an optimal transaction between two investors to minimize their risks. We define a dynamic entropic risk measure using backward stochastic differential equations related to a continuous-time single jump process. The inf-convolution of dynamic entropic risk measures is a key transformation in solving the optimization problem.

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