Data-Centric Approach to Digital Twin Modeling of Production Lines

Digital twin(DT) is a virtual replica of a physical world that has become one of the most important ideas in the manufacturing industry’s digital revolution. DT modeling is a vital issue in building a DT of a production line. In this paper, a method is proposed to address the difficulties of complicated production line business and data heterogeneity. The method focuses on essential data in the production line and creates conceptual and information models based on the ArtiFlow model and AutomationML(AML). Conceptual models are mainly used to describe and analyze the business activities of the production line, and information models describe real production lines in the form of XML files. The proposed modeling approach has been applied to a real-world clothing production line to demonstrate its feasibility and effectiveness.

Identifying Counterexamples Without Variability in Software Product Line Model Checking

Product detection based on state abstraction technologies in the software product line(SPL)is more complex when compared to a single system.This variability constitutes a new complexity,and the counterexample may be valid for some products but spurious for others.In this paper,we found that spurious products are primarily due to the failure states,which correspond to the spurious counterexamples.The violated products correspond to the real counterexamples.Hence,identifying counterexamples is a critical problem in detecting violated products.In our approach,we obtain the violated products through the genuine counterexamples,which have no failure state,to avoid the tedious computation of identifying spurious products dealt with by the existing algorithm.This can be executed in parallel to improve the efficiency further.Experimental results showthat our approach performswell,varying with the growth of the system scale.By analyzing counterexamples in the abstract model,we observed that spurious products occur in the failure state.The approach helps in identifying whether a counterexample is spurious or genuine.The approach also helps to check whether a failure state exists in the counterexample.The performance evaluation shows that the proposed approach helps significantly in improving the efficiency of abstraction-based SPL model checking.

RECONFIGURABLE PRODUCTION LINE MODELING AND SCHEDULING USING PETRI NETS AND GENETIC ALGORITHM

In response to the production capacity and functionality variations, a genetic algorithm （GA） embedded with deterministic timed Petri nets（DTPN） for reconfigurable production line（RPL） is proposed to solve its scheduling problem. The basic DTPN modules are presented to model the corresponding variable structures in RPL, and then the scheduling model of the whole RPL is constructed. And in the scheduling algorithm, firing sequences of the Petri nets model are used as chromosomes, thus the selection, crossover, and mutation operator do not deal with the elements in the problem space, but the elements of Petri nets model. Accordingly, all the algorithms for GA operations embedded with Petri nets model are proposed. Moreover, the new weighted single-objective optimization based on reconfiguration cost and E/T is used. The results of a DC motor RPL scheduling suggest that the presented DTPN-GA scheduling algorithm has a significant impact on RPL scheduling, and provide obvious improvements over the conventional scheduling method in practice that meets duedate, minimizes reconfiguration cost, and enhances cost effectivity.

Binary Oriented Feature Selection for Valid Product Derivation in Software Product Line

Software Product Line(SPL)is a group of software-intensive systems that share common and variable resources for developing a particular system.The feature model is a tree-type structure used to manage SPL’s common and variable features with their different relations and problem of Crosstree Constraints(CTC).CTC problems exist in groups of common and variable features among the sub-tree of feature models more diverse in Internet of Things(IoT)devices because different Internet devices and protocols are communicated.Therefore,managing the CTC problem to achieve valid product configuration in IoT-based SPL is more complex,time-consuming,and hard.However,the CTC problem needs to be considered in previously proposed approaches such as Commonality VariabilityModeling of Features(COVAMOF)andGenarch+tool;therefore,invalid products are generated.This research has proposed a novel approach Binary Oriented Feature Selection Crosstree Constraints(BOFS-CTC),to find all possible valid products by selecting the features according to cardinality constraints and cross-tree constraint problems in the featuremodel of SPL.BOFS-CTC removes the invalid products at the early stage of feature selection for the product configuration.Furthermore,this research developed the BOFS-CTC algorithm and applied it to,IoT-based feature models.The findings of this research are that no relationship constraints and CTC violations occur and drive the valid feature product configurations for the application development by removing the invalid product configurations.The accuracy of BOFS-CTC is measured by the integration sampling technique,where different valid product configurations are compared with the product configurations derived by BOFS-CTC and found 100%correct.Using BOFS-CTC eliminates the testing cost and development effort of invalid SPL products.

Multi-objective reconfigurable production line scheduling for smart home appliances

In a typical discrete manufacturing process,a new type of reconfigurable production line is introduced,which aims to help small-and mid-size enterprises to improve machine utilization and reduce production cost.In order to effectively handle the production scheduling problem for the manufacturing system,an improved multi-objective particle swarm optimization algorithm based on Brownian motion(MOPSO-BM)is proposed.Since the existing MOPSO algorithms are easily stuck in the local optimum,the global search ability of the proposed method is enhanced based on the random motion mechanism of the BM.To further strengthen the global search capacity,a strategy of fitting the inertia weight with the piecewise Gaussian cumulative distribution function(GCDF)is included,which helps to maintain an excellent convergence rate of the algorithm.Based on the commonly used indicators generational distance(GD)and hypervolume(HV),we compare the MOPSO-BM with several other latest algorithms on the benchmark functions,and it shows a better overall performance.Furthermore,for a real reconfigurable production line of smart home appliances,three algorithms,namely non-dominated sorting genetic algorithm-II(NSGA-II),decomposition-based MOPSO(dMOPSO)and MOPSO-BM,are applied to tackle the scheduling problem.It is demonstrated that MOPSO-BM outperforms the others in terms of convergence rate and quality of solutions.

Research on Theories and Techniques of Irrigation for Safeguarding Seed Production of Two-Line Hybrid Rice

By inducing frequency, intensity and duration of lower temperature in the middle and last ten-day periods in August in the rice-growing areas of southern China, increasing temperature for safe seed production was defined as 2℃. During the sensitive period of fertility, characters of panicle height and canopy structure of TGMS rice, Pei＇ai64S, were measured. Results showed that temperature changes caused by irrigation in fields were below 40 cm of rice plant, and heating effect was significant at 20 cm when the temperature was increased by 3.1 ℃. For the present study, the following irrigation techniques were put forth： the water depth of 15-20 cm, current water used, irrigating after 17：00 and bailing at 10：00 in sunny or cloudy weather, irrigating on whole day, in shady or rainy weather, increasing inflows and outflows in large fields. In the present experiment, pollen fertility and self-fertilized seed setting rate accepted that the techniques were feasible and effective for against lower temperature and safeguarding seed production of two-line hybrid rice.

Assembly Unit Resource Balancing Strategy based on Discrete Production Mode

Aiming at the characteristics of obvious block division and strong discreteness in the assembly production mode of electronic products,this paper proposes a composite U-shaped flexible assembly line model,and establishes a multi-objective optimization mathematical model on this basis.According to the characteristics of the model,the improved ranked positional weight(RPW)method is used to adjust the generation process of the initial solution of the genetic algorithm,so that the genetic algorithm can be applied to the block task model.At the same time,the adaptive cross mutation factor is used on the premise that tasks between different blocks are not crossed during cross mutation,which effectively improves the probability of excellent individuals retaining.After that,the algorithm is used to iterate to obtain the optimal solution task assignment.Finally,the algorithm results are compared with actual production data,which verifies the validity and feasibility of the assembly line model for discrete production mode proposed in this paper.

STUDY ON THE LOG PRODUCTION LINE IN LOG YARD

The article deals with the prduction lines in log yard by investigating the utilizationof machines in forest areas,presents the methods and rules of differentiating the log productionlines and also summarizes the formation and development of three kinds of log production lines innortbeast forest areas of China.It gives different combination types of log production lines andtheir applications, so it is significant for us to evaluate and standardize the log Production lines.

Minimizing Makespan on Mixed Mass Production Lines of Two and Three Machines

The objective of the research discussed in this paper has been to find an optimal schedule on mixed mass production lines of two and three machines. Johnson's rule on flow shops is generalized to mixed mass production lines. Scheduling methods on three-machine lines are proposed for six special kinds of data of processing times of jobs. The scheduling method on two-machine lines is also proposed.

Constructing the Virtual Production Line

In order to study the constructing technology of virtual production line, the structure model of virtual production line was presented, and the object oriented technique was used to establish its basic classes and relevant models, including solid model, behavior model and object oriented Petri net based control model, and based on this, the constructing of virtual production line was realized. The application proved that the virtual production line had many good characteristics, such as visualization, interaction, multi layer and reusability, and it's an efficient tool of analyzing and modeling for layout planning and rapidly reconfiguring of production line.

Improved Algebraic Model for Serial Production Lines with Limited Buffer Sizes

The ordered event model is improved to describe serial production lines with limited buffer sizes. The improved model hasthe same computational burden as the original one and can be constrUcted directly according to given principles. Several simulationexamples are cited to verify this improved model. Extensions and open problems are also indicated. By means of this new model, serialProduotion lines with limitations of resources can be stUdied analytically.

Generalized CAPP and synthetic evaluation strategy for production line of accuracy welding

This paper presents generalized CAPP （G-CAPP） method which deals with macro process planning for multiobjective in the planning stage of production line of accuracy welding （PLAW） based on the features of accuracy welding production （ AWP ）. G-CAPP offers foundations for prototype design and general equipment sorting, production capacity predication and production analysis by means of simulation and optimization. A synthetic hierarchy evaluation （SHE） model for G-CAPP established according to the planning objective is utilized to estimate the alternate processing plans by using membership function and analytic hierarchy process （AHP） of operational theory. The assembly welding line of hydraulic torque converter （HTC） is as an example of typical A WP to explicate G-CAPP and synthetic evaluating strategy of PLAW. The feasible and rational process configuration strategies of HTC assembly welding line are pointed oat under different planning objective.

Application of Industrial Robots in Stamping Automation Production Line

Since the reform and opening up, China's economy has developed rapidly and the society has been continuously improving. At the same time, in order to facilitate people's travel, the automobile industry has emerged, which has brought great convenience to people's production and life, and has also promoted the progress of society. In recent years, au-tomation technology has been continuously researched and developed by people, and it has been widely used in people's production and life. In order to improve the efficiency and modernization level of the automobile industry, the paper studies the application of industrial robots in the stamping automation production line, hoping to adapt to the new trend of economic development.

Development of Exterior Anti-corrosion Coating Production Line for Large Diameter Hot Bent Pipes

The epoxy powder exterior anti-corrosion coating production line for bent pipes with a single (double) course production is a technologically advanced bent pipe anti corrosion method with cost efficiency, environment friendliness and stable coating quality. The quality of the coating on the bent pipe fully meets the requirements of the current national and industrial standards. The application of the technology has filled the gap in the bent pipe anti corrosion coating area of China, and leads the world technologically. With this technology the coating quality of the bent pipe has greatly improved, resulting in significant social and economic benefits. With the use of the technology in various large scale pipeline projects such as the "West to East Gas Pipeline Project", it will exhibite a greater potential in the future pipeline projects with a broad application prospect.

An Energy Saving Glass Deep Processing Line Put into Production in Hubei

On July 16, 2013, the first low-E energy saving glass deep processing line of Hubei Zhongyi Glass Co., Ltd. was put into production in Changyang County of Hubei Province. Low-E glass is a kind of new glass featured with good lighting, thermal insulation, and ultraviolet radiation resistance. So far contracts worth about CNY 50 million have been signed.

Production Line for Floating Glass

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Layout and Simulation Design of Intelligent Manufacturing Production Line via Visualone

NC machining of parts and components is developing in the direction of automation and intelligence.In addition,the automatic production line puts forward higher requirements for the overall layout,technological process and production tempo.The layout and simulation of the production line can more directly reflect the problems that may occur in the operation of the production line,and solve these problems through scientific methods.This project uses VisualOne software to simulate the operation of the intelligent manufacturing production line,which can directly find the existing problems in the layout of the production line and the process of the craftsmen,and optimize the layout of the production line.In addition,it can provide reliable support for the equipment procurement and on-site construction of the intelligent manufacturing automation production line in the later stage.