МОДЕЛИ И МЕТОДЫ СИНТЕЗА СТРУКТУРЫ ТЕХНОЛОГИЧЕСКОГО ПРОЦЕССА ОБРАБОТКИ ДЕТАЛЕЙ НА ПОТОЧНОЙ ЛИНИИ ИЗ СТАНКОВ СО СТАЦИОНАРНЫМ ПРИСПОСОБЛЕНИЕМ

A problem of design of a flow line composed of stationary machines is considered. Mathematical models and methods for synthesis of manufacturing process structure are proposed. The models take into account main technological and structural constraints with the criterion of minimizing the line equipment cost. A decomposition scheme for solving the initial problem and its formulation in terms of a mixed linear problem are developed. Computational results are also presented.Рассматривается задача проектирования поточной линии, компонуемой из однопозиционных агрегатных станков со стационарным приспособлением, для обработки деталей одного наименования. Предлагаются математические модели и методы синтеза структуры технологического процесса обработки на ней. Критерием качества искомого решения принимается оценка стоимости оборудования линии. Учитываются основные технологические и конструктивные ограничения. Предлагается декомпозиционная схема решения исходной задачи и ее сведения к задаче смешанного линейного программирования. Приводятся результаты вычислительных экспериментов

МОДЕЛЬ СМЕШАННОГО ЦЕЛОЧИСЛЕННОГО ЛИНЕЙНОГО ПРОГРАММИРОВАНИЯ ДЛЯ СИНТЕЗА ТЕХНОЛОГИЧЕСКОГО ПРОЦЕССА ПОСЛЕДОВАТЕЛЬНОЙ ОБРАБОТКИ ГРУППЫ ДЕТАЛЕЙ НА ПОТОЧНОЙ ЛИНИИ ИЗ СТАНКОВ СО СТАЦИОНАРНЫМ ПРИСПОСОБЛЕНИЕМ

A problem of design of a flow line composed of stationary machines for sequential batch machining is considered. A MIP model for synthesis of manufacturing process structure is proposed. The model takes into account main technological and structural constraints with the criterion of the minimal line equipment cost. Results of solving a real industrial example are also presented.Рассматривается задача проектирования поточной линии, компонуемой из однопозиционных агрегатных станков со стационарным приспособлением, для последовательной обработки группы деталей различных наименований. Предлагается модель смешанного целочисленного линейного программирования для задачи синтеза структуры технологического процесса обработки на ней. Критерием качества искомого решения принимается оценка стоимости оборудования линии. Учитываются основные технологические и конструктивные ограничения. Приводятся результаты решения реальной проектной задачи

К ОПТМ ИЗАЦИИ ПРОЦЕССОВ ПОСЛЕДОВАТЕЛЬНОЙ ОБРАБОТКИ ПАРТИЙ ДЕТАЛЕЙ

A problem of optimal design of processes of sequential machining of multiple parts on rotary table machines is considered. Batches are processed in a given sequence. Parts of the same batch are located at the working positions of rotary table and are machined simultaneously. Operations are divided into groups which are performed by spindle heads or by turrets. Constraints on the design of spindle heads, turrets, and working positions, as well as on the order of operations are given. The problem is to minimize the estimated cost of machine equipment while reaching a given output. The proposed method to solve the problem is based on its formulation in terms of mixed integer linear programming. Computational results are reported.Рассматривается задача оптимального проектирования процессов последовательной обработки партий деталей на станках с поворотным столом. Последовательность обработки партий задана. Детали одной и той же партии устанавливаются на рабочих позициях станка и обрабатываются одновременно. Множество технологических переходов для обработки всех деталей разбивается на группы, которые выполняются с помощью шпиндельных или револьверных головок. Заданы ограничения, связанные с разбиением переходов по шпиндельным и револьверным головкам, рабочим позициям станка, а также порядком выполнения переходов. Задача заключается в минимизации оценки стоимости оборудования станка при обеспечении заданной производительности. Предлагаемый метод решения задачи основан на ее формулировке в терминах смешанного целочисленного линейного программирования. Приводятся результаты вычислительных экспериментов

The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). II. Constraints on star formation in ram-pressure stripped gas

Context: Several galaxies in the Virgo cluster are known to have large HI gas tails related to a recent ram-pressure stripping event. The Virgo cluster has been extensively observed at 1539 A in the far-ultraviolet for the GALEX Ultraviolet Virgo Cluster Survey (GUViCS), and in the optical for the Next Generation Virgo Survey (NGVS), allowing a study of the stellar emission potentially associated with the gas tails of 8 cluster members. On the theoretical side, models of ram-pressure stripping events have started to include the physics of star formation. Aim: We aim to provide quantitative constraints on the amount of star formation taking place in the ram-pressure stripped gas, mainly on the basis of the far-UV emission found in the GUViCS images in relation with the gas content of the tails. Methods: We have performed three comparisons of the young stars emission with the gas column density: visual, pixel-by-pixel and global. We have compared our results to other observational and theoretical studies. Results: We find that the level of star formation taking place in the gas stripped from galaxies by ram-pressure is low with respect to the available amount of gas. Star formation is lower by at least a factor 10 compared to the predictions of the Schmidt Law as determined in regular spiral galaxy disks. It is also lower than measured in dwarfs galaxies and the outer regions of spirals, and than predicted by some numerical simulations. We provide constraints on the star formation efficiency in the ram-pressure stripped gas tails, and compare these with current models.Comment: Accepted in A&A, 17 pages (including the appendix and "on-line" figures of the paper

A distributive approach for position control of clamps in a reconfigurable assembly fixture: .

International audienceHydraulic actuator is a type of clamp used in a reconfigurable assembly fixture for exact positioning and effective immobilisation of workpiece during the assembly process. However, due to their nonlinearity, there is a need to design a control system for their effective performance. This study presents a distributive approach to mathematical modelling and position control of multiple hydraulic actuators used as a clamping system in a reconfigurable assembly fixture. The electrohydraulic system is verified experimentally in order to observe the synchronisation of the hydraulic actuators. The mathematical model of the system is developed in the Simulink environment. A Simulink model of the system is developed from the mathematical model and simulated with a fuzzy-PID controller in order to obtain the response of all the actuators and other operating characteristics of the system. Simulation results are shown graphically in order to verify the theoretical development

A distributive approach for position control of clamps in a reconfigurable assembly fixture: .

International audienceHydraulic actuator is a type of clamp used in a reconfigurable assembly fixture for exact positioning and effective immobilisation of workpiece during the assembly process. However, due to their nonlinearity, there is a need to design a control system for their effective performance. This study presents a distributive approach to mathematical modelling and position control of multiple hydraulic actuators used as a clamping system in a reconfigurable assembly fixture. The electrohydraulic system is verified experimentally in order to observe the synchronisation of the hydraulic actuators. The mathematical model of the system is developed in the Simulink environment. A Simulink model of the system is developed from the mathematical model and simulated with a fuzzy-PID controller in order to obtain the response of all the actuators and other operating characteristics of the system. Simulation results are shown graphically in order to verify the theoretical development

MODELS AND METHODS FOR SYNTHESIS OF MANUFACTURING PROCESS STRUCTURE FOR MACHINING AT FLOW LINE OF STATIONARY MACHINES

A problem of design of a flow line composed of stationary machines is considered. Mathematical models and methods for synthesis of manufacturing process structure are proposed. The models take into account main technological and structural constraints with the criterion of minimizing the line equipment cost. A decomposition scheme for solving the initial problem and its formulation in terms of a mixed linear problem are developed. Computational results are also presented

MIP MODEL FOR SYNTHESIS OF MANUFACTURING PROCESS STRUCTURE FOR SEQUENTIAL BATCH MACHINING AT FLOW LINE OF STATIONARY MACHINES

A problem of design of a flow line composed of stationary machines for sequential batch machining is considered. A MIP model for synthesis of manufacturing process structure is proposed. The model takes into account main technological and structural constraints with the criterion of the minimal line equipment cost. Results of solving a real industrial example are also presented

MIP-based heuristics for batch machining at rotary transfeer machines

A problem of the optimal design of a rotary transfer machine with turrets for machining multiple parts is considered. Parts are located at the loading position of rotary table in a given sequence and they are processed simultaneously on several working positions. At each working position, several machining modules can be installed to process the operations assigned to this position. They are activated sequentially or simultaneously. Constraints related to the design of machining modules, turrets, and working positions, as well as precedence constraints related to operations, are given. The problem consists in minimizing the estimated cost of the transfer machine, while reaching a given output and satisfying all the constraints. The proposed method is based on solving a sequence of subproblems generated using MIP-recombination