Hegen Xiong

A simulation-based study of dispatching rules in a dynamic job shop scheduling problem with batch release and extended technical precedence constraints

This paper considers a simulation-based analysis of dispatching rules for scheduling in a dynamic job shop with batch release taking into account the extended technical precedence constraint which is a new term defined as the extension of conventional routing-based technical precedence constraint in our paper. With respect to tardiness-related measures, the relative performances of some widely-used dispatching rules as well as four new ones proposed in our paper are evaluated for different settings of the model parameters. The results of the simulation study demonstrate the effectiveness of the four new proposed dispatching rules, and also reveal that the relative performance of dispatching rules can be affected by some model parameters. For the standard job shop scheduling problem model, where there are no extended technical precedence constraints between jobs, as well as for the models taking into account the extended technical precedence constraint, it is shown that for minimizing the total tardiness and the percentage of tardy jobs, the four new proposed dispatching rules are very effective under relatively loose due date. With respect to tardiness-related objectives, the relative performance of the analyzed dispatching rules can be affected by changing not only the levels of the extended technical precedence constraint, but also the due date tightness.

Numerical simulation of the influence factors for rotary kiln in temperature field and stress field and the structure optimization

With the development of metallurgical industry and the improvement of kiln technology, the processing properties of kiln equipment are being paid more attention. The rotary kiln is one of the most representatives of the furnace equipment; higher requirements of the rotary kiln are put forward in response to the call of the national energy saving and emission reduction. That is, the new designed equipment has the characteristics of the optimal energy consumption and stable performance. In order to analyze the energy consumption of the rotary kiln, it is necessary to study the heat transfer process of the rotary kilns. The three-dimensional numerical model of the rotary kiln is set up by using the finite element technology. After analyzing the data, it is found that different thicknesses of the kiln crust and different working conditions have certain influence on the rotary kiln’s temperature field and stress field. After analyzing the result of the simulation, the temperature of the rotary kiln’s outer wall has an approximate linear relationship with the thickness of the kiln crust. Changing the thickness of the kiln crust will not only alter the value of the maximum stress but also have influence on the position of maximum stress. The increase in the thickness of the kiln crust can reduce the extreme value of stress. When the wind speed of induce fan inside the kiln is larger, the temperature of each layer will be relatively high as well, and the temperature curve is softer, and the temperature variation is more stable. It has also been found that when the comprehensive coefficient of heat exchange outside the kiln surface is larger, the thermal stress created by the body of kiln is smaller. The phenomenon of excessive thermal stress can be improved by changing the outer surface ventilation conditions of the rotary kiln. In order to ensure that the high temperature of the kiln wall has no influence on working wheels, and make sure the temperature of the kiln wall is well-distributed along the length direction of the kiln, the thickness of the kiln crust along the length direction is changed, and the structure of the cylinder with wheels on it is altered. After further numerical simulation, the optimized thickness of the kiln crust and kiln structure is found, and the above problem is solved effectively. The results can reduce the inputs of rotary kiln design and the production costs. It can also reduce energy consumption, and some guidance is given on the production process of kilns.

Research on steady-state simulation in dynamic job shop scheduling problem

A systematic research of steady state for the dynamic job shop scheduling problem with jobs releasing continuously over time has been conducted in this article. A simulation scheduling test for the purpose of factor analysis is designed and carried out first and then another simulation scheduling test for the purposes of disciplinarian investigation is conducted. The heuristic dispatching rule algorithm is adopted in the simulation scheduling. The test data are processed and analyzed using SPSS13.0. The results indicated that the dominant factor that can characterize the shop steady state is the shop utilization level. Besides, the relationship between the number of jobs arrived at the shop and the steady state of the shop can be described by a quadratic curve preferably. Results obtained in this article make significant sense for the study of simulation scheduling of dynamic job shop scheduling problem and also for the optimum design of the shop system.

Design and modeling of a new variable stiffness robot joint

Safety constraints are a major aspect for human robots interaction. A new variable stiffness robot joint (VSR-joint) is proposed for operating safely. The proposed concept allows for the development of an actuation unit with a wide range of stiffness and a fast stiffness regulation response. The design of VSR-joint is compact and integrated highly and the operating is simply. The mechanics, the principle of operation and the model of the VSR-joint are proposed. The principle of operation of VSR-joint is based on a lever arm mechanism with a continuously regulated pivot point. The VSR-Joint features a highly dynamic stiffness adjustment along with a mechanically programmable system behavior. This allows an easy adaption to a big variety of tasks. Preliminary results are presented to demonstrate the fast stiffness regulation response and the wide range of stiffness achieved by the proposed VSR-Joint design.

Research on Fuzzy Intelligent Control of Coke oven Heating

The control principle of combining the intermittent heating control with the heating gas flow adjustment was adopted for coke oven heating control. Intelligent control strategy and an integrated model of coke oven heating were proposed, which combined two feedback control, one feedforward control and intelligent control. According to coking mechanism, heating supplied feedforward model was built, and carbonization index feedback model was proposed in the model to control coking management of coke oven. Flue temperature soft measurement model based on linear regression and neural network was built to supply temperature feedback control. According to artificial experience and actual condition in the plant, the fuzzy rules were generated. The proper amount of stopping heating time and heating gas flow were computed taking the operation condition of coke oven into account. Actual run results show that the strategy and model can solve the large inertia effectively and shorten adjustment time. So the system satisfies the actual production needs, and has great practical value.

Gear reducer optimal design based on computer multimedia simulation

In recent years, with application of optimization technology and computer technology in the field of optimal design, it has become an essential course for mechanical students. How to effectively apply multimedia optimal methods to the optimal design course is the problem that we need to solve. The teaching mode of optimal design course is explored by multimedia software simulation analysis. The existing problems in the teaching of optimal design are introduced in this dissertation. And the case of the optimal design teaching according to the teaching method of multimedia software is realized. The finite element analysis of reducer and the application of genetic algorithm in it, for example, emphasize how multimedia simulation can be effectively applied to optimal design. We take the gear reducer as a case to carry out the modal analysis and gear meshing analysis and optimize its structure by using genetic algorithm. Making full use of multimedia software, combined with the course knowledge points and simulation software to cultivate the actual design and application capabilities, paying attention to the acquisition of optimization design methods, could improve the quality of optimization design personnel training. The results show that integrating multimedia simulation into optimization design teaching could be a good way to improve the practice of teaching and to promote knowledge learning and optimal design capabilities. It has a great significance for the development and application of optimal design based on multimedia.

Gesture recognition based on binocular vision

A convenient and effective binocular vision system is set up. Gesture information can be accurately extract from the complex environment with the system. The template calibration method is used to calibrate the binocular camera and the parameters of the camera are accurately obtained. In the phase of stereo matching, the BM algorithm is used to quickly and accurately match the images of the left and right cameras to get the parallax of the measured gesture. Combined with triangulation principle, resulting in a more dense depth map. Finally, the depth information is remapped to the original color image to realize three-dimensional reconstruction and three-dimensional cloud image generation. According to the cloud image information, it can be judged that the binocular vision system can effectively segment the gesture from the complex background.

Survey of the selection and evaluation for dispatching rules in dynamic job shop scheduling problem

Dispatching rule is an effective method for solving dynamic job shop scheduling problem in practical production. The development, classification and characteristics of dispatching rules were reviewed in this paper, and the research hotspots of dispatching rules including the selection and evaluation methods were summarized. The selection methods of dispatching rules were introduced in detail which includes the popular steady state simulation method and the effective artificial intelligence method. The research results and conclusions of simulation methods, expert system, machine learning methods and artificial neural network methods that were applied to the selection of dispatching rules were presented. In addition, the evaluation of dispatching rules including indicators and methods were illustrated. Finally the direction of future research was pointed out aiming at the shortcomings of the existing dispatching rules.

Kinematics and Workspace of a 4-DOF Hybrid Palletizing Robot

We presented the kinematical analysis of a 4-DOF hybrid palletizing robot. The palletizing robot structure was proposed and the arm model of the robot was presented. The kinematical analysis of the end robotic manipulator was given. As a result, the position, velocity, and acceleration curves as well as the maximum workspace were demonstrated by simulation in Matlab. This study would be useful for the kinematical characteristics of the 4-DOF palletizing robot in space.

Quantum rotation gate in quantum-inspired evolutionary algorithm: A review, analysis and comparison study

Abstract Quantum-inspired Evolutionary Algorithm (QEA) is a kind of intelligent algorithm which widely and effectively used in many fields. In QEA, the basic and common operations usually include quantum chromosome observation and quantum gate update. Quantum rotation gate (QRG) is the most commonly used operator for the operation of quantum gate update, which has a significant influence on the performance of QEA. Many kinds of QRGs have been proposed with different methods to set the only parameter of QRG, i.e., rotation angle. In this paper, a study on classification of QRG is first conducted with respect to rotation direction and magnitude of rotation angle by analyzing and summarizing various kinds of QRGs in literature, and then the corresponding definitions, descriptions and analyses are presented. Furthermore, in order to investigate and compare performances of different QRGs, we set 21 kinds of QRG schemes based on the classification of rotation direction and magnitude of rotation angle. Four typical complex function optimization problems and a 0–1 knapsack problem are selected as experiment objects to test the 21 kinds of schemes. Comprehensive processing and analyzing for the experiment data are conducted, which draws some valuable conclusions for the more reasonable and more effective applications of QEA.