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The article discusses the problem of total waste separation in the frame of a computer simulation design of these systems. The aim of the article is to employ computer simulation, modelling and logistics for the needs of total separation of waste and its recycling into the form of raw materials and re-usable resources in practice. The results of the computer simulation show that by using total separation and waste recycling in the specifically analysed region, it is possible to produce approximately 7700 tons of recycled paper, 2400 tons of multilevel packages, 8000 tons of glass, 3000 tons of old textiles, 3500 tons of iron, approximately 1500 tons of non-ferrous metals, approximately 2700 tons of wooden pallets, approximately 1200 tons of rubber granulate, to process approximately 800 tons of dangerous waste, 2400 tons of electro waste, 2100 tons of gravel, 840 tons of sand and to liquidate approximately 3200 tons of non-recyclable waste during the whole year. [ABSTRACT FROM AUTHOR]

Modelling and simulation is a highly progressive area that can create significant financial savings for companies that use it. Simulations can be used in the production area to analyse or verify certain decisions and conditions, on the basis of which correct measures can be taken. However, modelling is a highly time-consuming and therefore costly process, which narrows its use for decisions in high-priority processes. The content of the article is a description and results of the created tool designed for quick analysis of the workplace using simulation. The entire process of functioning was described through Unified Modeling Language (UML) diagrams. Siemens's Tecnomatix Plant Simulation software was used to create the tool. The tool itself was compared both to the length of creation of the mid-size simulation model and the time variance of model creation in a standard way. The tool can be used to reduce the time needed to create a model that is used to analyse the selected workplace, which ultimately increases the productivity of the simulation expert. (Received in May 2022, accepted in July 2022. This paper was with the authors 1 week for 1 revision.) [ABSTRACT FROM AUTHOR]

To improve the reliability of the discrete event simulation model, it is necessary to represent, the best way possible, the operator behaviour and his subsequent performance. Deterministic simulation models often overestimate the production capacity of manufacturing systems since they don´t consider some key relationships, such as the impact of human factor performance on productivity. This paper, with the aid of statistical techniques, analyses the total of boards produced, taking into consideration different periods of work shifts to apprehend the variability of human performance at different points throughout the day. Therefore, this paper aims to investigate the impact of human performance on the work shift and, hence, on the computer model's validity. Results reveal that human performance has a significant impact on the productivity of the assembly line investigated and affected the reliability of production forecasts through stochastic simulation. [ABSTRACT FROM AUTHOR]

This paper addresses the effect of probabilistic selling on inventory decisions and the expected profit through demand reshaping and demand substitution. By considering a scenario with two higher-priced specific products and one lower-priced probabilistic product, we construct a new newsboy-type inventory model with demand reshaping and substitution. A simulation study is implemented to explore extensively the effects of demand uncertainty, demand correlation, price sensitivity and price discount on the inventory decisions and profitability of probabilistic selling. Finally, we provide insightful managerial implications of the nature of inventory management mechanism of probabilistic selling. [ABSTRACT FROM AUTHOR]

The paper deals with the streamlining of production logistics by using the example of a specific construction production company -- through design via ExtendSim computer simulation. The issue concerns researching procedures for the company's long-term sustainable competitiveness in the production of building components in a very competitive market. The research aims to use computer simulation as a means for the regular streamlining of production logistics in a specific manufacturing company, focusing on the production of building parts. The company in question produces building material, which takes place in two types of kilns: the first for drying products, the second for product firing. Yet, these operations represent a bottleneck in terms of production logistics. The final packaging of the daily production of construction products is approximately 280-320 pallets in 12 hours. Yet by adjusting the parameters of production logistics in individual parts of material flow, production can be boosted by 14.96 %. The given solution can be practically applied to modernise production, without additional cost, simply by changing work organisation and the production's bottleneck parameters [ABSTRACT FROM AUTHOR]

In this paper, we present and propose the interactive push-pull lean game with a specific approach for training/testing of production processes. With our approach of combining the psychologically effective physical lean game and the simulation lean game for deeper analyses of the production process, we can successfully overcome the communication and motivation problems of production and management workers when new production strategies are being introduced into the company to raise the competitiveness. The game only takes two hours and it has been proven to be effective with leadership teams and shop floor workers alike in more than 50 real-case production environments. The game is played in two parts where each part is in sharp contrast to the other with respect to results. Once the participants of the game see the effects of both production strategies, they become extremely engaged and motivated, and it becomes much easier to manage organizational improvements. In the third chapter of the paper, we present the Virtual factory computer models of the game dynamic, showing the same results as obtained with groups. The two simulation models serve to test and verify the interactive game. The paper ends with the discussion and conclusions. [ABSTRACT FROM AUTHOR]

This paper proposes the research method to comprehensively apply the time Petri net model and the Flexsim simulation model by taking interior assembling and production logistics system of an automobile manufacturing assembly workshop as the application background, and taking improvement for the production efficiency and production value of the logistics system as the target. Using this method, we can simulate the actual production logistics, analyse the results and identify bottleneck problems, and propose targeted optimization methods to improve processes, reduce waste, improve efficiency, and prove the rationality and validity of the research method. [ABSTRACT FROM AUTHOR]

The success of small and medium enterprises to adapt to constant changes in the environment largely depends on the different strategies and management decisions taken by managers at the operational level. This paper is searching for a tool that would allow managers at all levels to consider the effects of their decisions on the success of the enterprise as a whole. In this sense, the application of system dynamics developed one modular simulation model of business processes of SMEs. Developed model recognizes the specificities of SMEs, such as a large range of products, the use of a wide variety of materials, production in small batches and requests for reduction of lead time (Lead Time). The effects of various strategies and management decisions can be observed by monitoring the dependence of performance measures of simulated process on values of model parameters. Through four experiments the effects of changes in inventory management policies, the availability and size of the lot were simulated. The results of experiments showed that the variation of the model parameters should be oriented simultaneously towards several of the aforementioned directions. [ABSTRACT FROM AUTHOR]

Dropper is the key component of catenary in high-speed railways. The prediction of the fatigue life of dropper is accomplished using alternating load characteristics. Simulation method for obtaining the dynamic internal load of the dropper in previous studies was insufficient for accurate requirements in predicting dropper life. According to realistic working conditions in the simulation environment, this study proposed a simulation method considering horizontal vibration behaviour for the dropper. The horizontal vibration phenomenon of a dropper was determined on the basis of observing and measuring a real high-speed railway. Moreover, a test for the reappearance of horizontal vibration in the laboratory was performed. The dropper was modelled with multibody dynamics. Finally, the horizontal vibration behaviour of the dropper on-site was reproduced in a laboratory test and computer simulation. Results demonstrated that the coefficient of association between the virtual sensor load in a simulation environment and the real sensor load in a laboratory test is 0.9578. The proposed method provides an accurate approach to simulating the load of the droppers under real working conditions. (Received in July 2019, accepted in November 2019. This paper was with the authors 1 month for 2 revisions.) [ABSTRACT FROM AUTHOR]

This paper establishes the models of the steelmaking continuous casting (SCC) process, and proposed the improved algorithms for this problem. The simulation results of a computerized scheduling system are also given to prove the model. The SCC process scheduling problem is very difficult to get a good performance solution in practice. The scheduling of the SCC process requires that each cast plan is processed on time, and the charges should be processed continuously for the same caster in the same cast, as well as the waiting time of the charges cannot be conflicted mutually in the same converters. We propose a quantum-behaved particle swarm optimization (QPSO) and improved algorithm strategy. The results show that the QPSO is very efficient for solving the SCC production scheduling problem, especially for large scale problem. [ABSTRACT FROM AUTHOR]

This paper presents a study for assessing the dynamic structural deformations of one of the most modern, and portable, measurement equipment: the Coordinate Measuring Arms (CMAs or AACMMs). The study of the measurement errors derived from the use of these instruments is still controversial due to a certain lack of traceability and reliability in measurements due to the influence of the human factor acting on a complex 3D structure (with 6 or 7 degrees-of-freedom). When contact measurements are taken into account, the human factor variable originates non-uniform contact forces, lack of stability, different velocities and accelerations, among unpredictable probing trajectories. All these factors lead to conclude that in every manual measurement involving a CMA there is a structural dynamic deformation caused by the approach movement before probing a contact point as well as by the force exerted during probing. In order to determine the amplitude of this deformation and its distribution along the CMA structure a new methodology has been developed. Both depend on the followed trajectory and on the probing force amplitude and orientation. This work presents the methodology and steps required for the construction of the virtual simulation model. The method employs 3D modelling of all elements of the CMA structure, Finite Element Analysis (FEA) software and multibody simulation techniques with flexible bodies. This set of software tools is nowadays capable of creating dynamic virtual models for the dynamic analysis of complex mechanisms (machines, vehicles...) in optimization tasks. The application of these tools supposes a novel approach to the study of the CMA metrological behaviour. [ABSTRACT FROM AUTHOR]

Discrete Event Simulation (DES) is one of the most effective tools for planning, designing and improving material flows in production. One of the main weaknesses of operating DES is the exertion needed and costs spent on collecting and handling the input data from different organisation's data resources. To tackle the problem of the time consuming input data process for DES projects an Open Source (OS) tool, called Knowledge Extraction (KE) tool was developed. The tool reads data from several organisations' resources; analyses it and outputs it in a format that is applicable to be used by a simulation tool, all conducted in one automated process. The primary, readable to simulation software, output format follows the Core Manufacturing Simulation Data (CMSD). This paper presents the KE tool and a test implementation, as a first step towards the validation of the tool in a real case study in the medical industry. [ABSTRACT FROM AUTHOR]

The objective of the article is to present the linking of simulation and planning software. The paper begins with a review of recent literature as well as description of the problem under investigation. Following from practical requirements, five decision-making rules were implemented to the production process. In the final part, the overall results to ensure time and economic efficiency of the production process are presented. The obtained results show that the best option is to apply the rule during which the first part to be machined is the one that first enters the production process to ensure minimum production time, maximum machine load and limit machine costs. By application of this rule, the total production time accounts for 524 seconds at the total cost of 7914.60 €. The overall benefits of the research are being described in details in the final part of the article. [ABSTRACT FROM AUTHOR]

This paper attempts to overcome the defects of bottleneck recognition and scheduling optimization in open production line. For this purpose, the author analysed the impact mechanism of external disturbances and system configuration changes on the production line, and put forward a multibottleneck identification model for production line through computer simulation. Then, the proposed model was applied to optimize the scheduling of open production line. Specifically, the bottlenecks of production line were identified based on hierarchical clustering and multi-attribute decision-making, aiming to overcome the small candidate set and low accuracy of traditional bottleneck identification algorithms. The measured results show that the proposed algorithm has clear primary and secondary logics; the number of main bottleneck clusters decreased with the increase in the order; the number of machines in the main bottleneck cluster changed nonlinearly. The traditional genetic algorithm (GA) was improved in three aspects: the local optimum trap was avoided by enhancing population diversity; the iteration speed was accelerated with the introduction of adaptive crossover operator and genetic operator; without sacrificing the computing speed, the convergence quality was guaranteed through the addition of multivariate competition algorithm. The research findings provide new insights into the efficient operation of production line. [ABSTRACT FROM AUTHOR]

When designing simulation models of large-scale logistics systems in manufacturing, such as automotive industry or engineering and petrochemical production, creators of these models consider how to properly render the whole system in one simulation model as accurately as possible. One possible approach to designing such models is the application of a hierarchic structure. The structure groups and combines the essential elements of simulation models into larger units. The aim of the paper is to analyse and identify the potential of the computer simulation using a hierarchic structure for increasing the effectiveness of designing large-scale logistics systems in manufacturing. A case study from the automotive industry using EXTENDSIM software environment is used for that purpose. [ABSTRACT FROM AUTHOR]

It is well known that in an acoustic guitar, the hollow wooden body of the guitar, which forms the resonating chamber, plays an important role in the sound produced. In an electric guitar, the influence of the solid guitar body is not so crucial, yet some influence of the vibroacoustic material properties is expected but has not been scientifically confirmed so far. The aim of the research presented in this paper was to confirm the hypothesis and to investigate the influence of the material used for the solid body of an electric guitar on the final sound image. An experimental numerical model of the electric guitar was created to show how designers can be assisted with a tool that allows them to plan the characteristics of the sound to be produced at the design stage, when the material and shape for the body of the guitar have been determined. In order to develop a relevant numerical model of the electric guitar, we built a test bench to validate the numerical model. The results of the numerical simulation of the decay of the string vibrations as a function of the body material used agree well with the results of the experimental measurements, confirming the adequacy of the numerical model presented. [ABSTRACT FROM AUTHOR]

Vortex pumps are finding increasing use where abrasive fluids in petrochemical applications must be handled when pressure is readily available for transporting mixed materials in pumping applications. Related research on fine particle two-phase flow cannot meet the actual production requirements. Therefore, the characteristics of solid-liquid two-phase flow with high solid-phase content in pumps must be investigated. In this study, a two-stage vortex pump with a high demand for passing and steady ability is designed. The external characteristics of the pump, internal pressure field, velocity field, and solid distribution law are explored through high solid concentration and size changes. Results show that the shear stress transport turbulence model is found to be appropriate for the computational fluid dynamics analysis of the characteristics of the vortex pump well. The particle velocity and pressure at the monitoring point at the tongue of the volute are higher, thereby aggravating the wear. With the increase in particle volume concentration, the energy exchange between the media increases, and the hydraulic loss of the flow field increases. [ABSTRACT FROM AUTHOR]

Production planning and the development of manufacturing production scheduling are two important operational management tasks. The results of these tasks will strongly influence the development of corporate profits, as well as the efficiency of utilization of resources. Considering the production scheduling problems in production plans can effectively avoid conflicts between the specific implementation production plan and the actual situations, and ultimately maximize resource utilization efficiency. This paper attempts to establish an integrated optimization model of production planning and scheduling with consideration of logistics constraints. A modified heuristic algorithm is proposed to solve this problem. In the final portion of this paper, a simulation analysis is given to demonstrate the outstanding advantage of the model and the algorithm, which gives further thought for the production planning. [ABSTRACT FROM AUTHOR]

In this paper, a stability control strategy for underactuated biped robots is proposed based on imbalance degree. The dynamic models of single-leg support of underactuated biped robots are firstly illustrated. Based on the external disturbance force strength of the system, the motion process of an underactuated biped robot is partitioned into three stages according to the imbalance degree. In different stages, corresponding dynamic models, tracking, gesture and gait switching control are adopted. Analysis of simulation result shows that the proposed underactuated gait control method is stable, practicable in engineering, and satisfies the real-time requirement. [ABSTRACT FROM AUTHOR]

The number of work-related musculoskeletal disorders has been increasing in most industries and occupations. Since these injuries impose high costs on employers and society it is important to prevent it through ergonomic assessment and job redesign. The paper presents a research of the workplace ophthalmic nurse regarding strain and stress. In the workplace the Intravenous Fluorescein angiography or fluorescent angiography is made which is a technique for examining the circulation of the retina and choroids using a fluorescent dye and specialized camera. The working procedure is complex and since nurses must assist in several forced positions for longer time ergonomic analyses were made aimed to determine strain and stress at workplace. For assessment of body postures OWAS analysis was performed manually and using computer simulation. The results obtained using computer simulations are comparable to manually performed research for most body positions except for bent and twisted back. Body postures of upper limb, lower limb and neck were exposed as harmful for nurse during working procedure and according to OWAS changes are needed in near future. [ABSTRACT FROM AUTHOR]

This paper studies the influence of diverse friction models on the numerical analysis of an industrial skew rolling mill using FORGE®. The originality of the present contribution is the analysis of the effect of the friction model on important parameters, namely, consumed power, plastic deformation and surface temperature. The aim is to evaluate which of these friction models is appropriate for simulating these industrial processes. The high values of temperature, pressure and sliding velocity at the contacts make the assessment of the friction model incidence on the deformation and temperature evolution fundamental, given its importance on the thermomechanical processing of materials. As a conclusion, IFUM is not valid because of its sliding velocity approach. On the other hand, Neumaier presents the highest deviations in terms of experimental power. It is concluded that Tresca is valid for this sort of processes and Norton model gives the most accurate results for friction power, related to the high sliding conditions at the contact. [ABSTRACT FROM AUTHOR]

At present, AGV systems are an important part of numerous companies and their internal logistics systems. They are used to efficiently secure different types of transport processes in order to minimize operating costs. However, their reliable operation requires adequate setting and maintenance. Computer simulation is probably the most suitable option from a wide range of engineering methods with which to meet these requirements. This paper describes the development of a simulation model in the Tecnomatix Plant Simulation program to identify critical points of failure within a specific delivery process on the basis of a Milk Run system. Based on the results obtained, an appropriate solution was determined with which to make the whole process function more efficiently and reliably. [ABSTRACT FROM AUTHOR]

Simulations are widely used in manufacturing system design, production planning and decision making. The aim of this paper is to present the possibility of using Monte Carlo simulations in the production plan optimizing and in the project risk management. Optimization is accomplished through two different approaches which principles and results are mutually compared. According to the first approach, production optimization is performed via a deterministic model using the Generalized Reduced Gradient algorithm. The second approach is based on the stochastic model. The optimized production plan is submitted to risk analysis. Two approaches are demonstrated in order to reduce the rate of risk. The first way is modifying the production plan to increase the forecast reliability; the second approach is limiting the uncertainty of key variables. The detailed methodology enables implementing presented approaches in solving various optimization tasks. [ABSTRACT FROM AUTHOR]

Currently, robotic manufacturing cells entail complex decisions concerning sequencing issues due to uncertainty which arises in different parameters such as time to failure, time to repair and cycle times that can be effectively supported by computer simulation models. The paper is focused on part sequencing of a two-machine robotic cell in a flow shop which produces different parts. The process is supported by a single gripper robot to load/unload products and also in displacement within the system. This study considers machine failures and repair such that S2 cycle time and total production cost should be minimized. In this study, simulation facilitated input part sequence and also data envelopment analysis method is applied to trace the optimum sequence for satisfying the objective functions. Results through some numerical examples showed some simulation advantages specially to model many uncertainties and what if analysis. [ABSTRACT FROM AUTHOR]

Oil jet lubrication performance directly influences the operation, reliability and fatigue life of meshing gears working under high-speed and heavy-load conditions in the main reducer of rotorcraft. An oil-air two-phase mixture flow numerical simulation model for jet lubrication on the surface of a pair of meshing gears was established by the computational fluid dynamics (CFD) simulation code ANSYS/FLUENT. The effects of the spin flow caused by a high-speed rotating gear pair on the jet flow trajectory deviation were considered in the numerical simulation. The oil volume and oil pressure distribution characteristics of the meshing area were obtained and compared according to different nozzle position layouts, and the optimal nozzle position layout was determined to obtain a maximum oil volume and oil pressure. A gear-jet-lubrication experimental system was built in which the meshing surface temperatures were measured by an infrared thermometer; meanwhile, the jet flow trajectories were photographed by a high-speed camera. The experimental and numerical simulation results were mutually validated and proved the proposed optimal design scheme for the nozzle position layout. [ABSTRACT FROM AUTHOR]

The anisotropy of frictional resistances is often omitted in finite element method (FEM) based numerical modelling of industrial processes of sheet metal forming. The aim of this paper is to analyse the effect of anisotropy of frictional phenomena on the formability of drawpieces. As a benchmark experiment, the formability of cylindrical cups is carried out, and as a benchmark material the deep drawing quality (DDQ) steel sheets are used. The effect of friction phenomena on the formability of cylindrical cups is studied using finite element based program ABAQUS/Standard 3DExperience R2016x HF2. The results of predicted location and height of ears allow concluding that material and frictional anisotropy of sheet metals are the main factors that determine high conformity of the finite element based numerical simulation results with the experiments. Comparison of numerical results demonstrates great potential of Hill yield criterion incorporated with the anisotropic friction model in accurate prediction of earing. [ABSTRACT FROM AUTHOR]

Taking traction helical gear of EMU CRH380A as an example, the meshing characteristics was analysed. Based on Pro/E, three-dimensional helical gears were modelled. Combined with ANSYS, the gears' contacts were analysed under multi-condition, such as start-up, continuous and high speed. Through transient dynamics, the distribution cloud of the equivalent stress and contact pressure in a meshing period are solved, which at different meshing position under different condition. And the contact state, the stress changes and distribution regularity in the meshing process were analysed. Then on the basis of the results, gear modification parameters were designed, and the modification gears finite element model were constructed. To compare gear contact stress distribution before and after being modified, it shows that the modification scheme can effectively reduce the gear meshing impact and the transmission noise. [ABSTRACT FROM AUTHOR]

The aim of this article is to create a simulation model of specific production system in Plant Simulation environment. The main production program that we monitor in this article is focused on the production of tapered roller bearings. Types of produced products are wide; therefore we focus attention on a material flow of one particular dimensional type of bearing. This article is divided into five parts. In the first part there is a theoretical overview of utilization of the system module Plant Simulation. The second part is focused on product that will be used for simulation process, concretely tapered roller bearing 32303A. Third part deals with analysis of simulated system model in Plant Simulation. Fourth section is oriented on proposal of monitored production system optimization in Plant Simulation and final fifth part is about benefits evaluation of the proposed solution. [ABSTRACT FROM AUTHOR]

Serial-parallel centrifugal pumps (SPCPs) are a new type of pump with two working conditions: high head with low flow and low head with high flow. However, the motor of SPCPs is easily burned because of its various operating conditions. To clarify the effect of the flow field on the non-overload characteristics of SPCPs, revealing the non-uniformity of the flow distribution is necessary. This study derived the velocity triangle theory of the pump, and a numerical simulation by 3D models was conducted to investigate the internal flow patterns of SPCPs. The magnitude of the flow deviation angle at different cross-sections was calculated to evaluate the non-overload characteristics under different operating conditions. The results showed that the formula of the maximum shaft power and the local flow rate were two important parameters of the non-overload interpretation of the pump. The simulated results were in good agreement with the experimental results at the designed flow rate. In addition, the flow deviation angle under the serial operating condition, which was more likely to achieve the non-overload characteristics, was evidently higher than that under the parallel operating condition. The conclusions solved the issue on the theoretical design of the non-overload characteristics considered in a non-uniform flow in SPCPs. [ABSTRACT FROM AUTHOR]

Dynamic behaviour of a micro-cantilever beam under periodic electro-thermal loading is studied in this paper. For certain applications the beam is required to vibrate at a particular frequency. Modal analysis using 3D finite element is used in order to find the geometrical parameters that makes fundamental frequency of the beam match the required frequency. Then non-linear dynamic thermoelastic analysis is conducted on the system to analyse the time-history (transient) behaviour of the beam and record its tip displacement. However, due to uncertainties and non-repeatabilities that are inherent properties of the system along with those associated with the manufacturing, final product is likely to have deviations from these estimated values (fundamental frequency and tip displacement). Thus, choosing a nominal (desired) design and studying the deviation in natural frequency and tip displacement via 2k factorial Design-of-Experiments (DOE), effect of uncertainties on the overall performance of the system is investigated. This allows finding the significance of individual parameters on the overall robustness of the design as well as potential interactions between various parameters. Finally, the expected behaviour of the micro-cantilever and its robustness to design and implementation uncertainties are elaborated and statements for robust design of this system are made. [ABSTRACT FROM AUTHOR]

We consider perishable inventory control with freshness-dependent demand under carbon emissions constraints. We propose two deteriorating inventory models with carbon emissions tax and the capand- trade mechanism, in which the demand is freshness dependent, carbon emissions come from inventory holding, shipping, and item deteriorating, and the objective is to maximize the profit per unit time. We characterize the existence and uniqueness of the solutions for the models. We analyse the impacts of carbon emissions tax, carbon emissions quota, and carbon price on inventory decisions, carbon emissions, and profit. We conduct simulation to generate managerial insights from our analytical results. [ABSTRACT FROM AUTHOR]

This paper aims to explore the optimization tactics of a dual-channel production and distribution network based on pre-sale mode to address the current situation of overstocked inventories in the apparel industry and considering the effect of changing production-distribution modes on apparel sales which results from the difference of order decoupling point. The research indicates that in the highly homogeneous apparel market, the pre-sale mode in which the products are made-to-order can utilize the highly efficient feedback of online pre-sales to provide guidance for traditional distribution channel by making accurate demand forecasts in a certain environment. This could help to resolve the problem of overstocked inventories by providing relative reference for the apparel industry in its subsequent operations. The mode of the production-distribution network after optimization is able to make reference to the real operations of pre-sale mode in the apparel industry. [ABSTRACT FROM AUTHOR]

In the field of hydraulic drive technology various power supply systems are used within different power unit set-ups. The both of two mostly used drive concepts in modern electrohydraulic systems, a variable displacement pump driven by constant speed electric motor and fixed displacement pump driven by a variable speed electric motor, have some disadvantages, especially regarding the increasing demand for maximum efficiency of the entire power unit without lowering the high dynamics. The combination of a variable pump and speed-controlled electric motor, offers the option of setting two parameters of the drive, the rotational speed of the motor and the pump flow-rate. Such a combination allows all power unit components to operate within the areas of their maximum efficiencies, the so-called maximum efficiency drive. A prerequisite for designing suitable controllers that would ensure the operations of individual components within the areas of maximum efficiency, regardless of the current operating point, is certainly knowledge about the efficiency area of the entire power unit. This paper presents a procedure for determining areas of efficiency, first on the basis of simulation and detailed models of each component, and later verification of the model using an experiment. [ABSTRACT FROM AUTHOR]

Nowadays the great attention has to be paid to warehouse. Theoretical analysis shows the need to optimise their activities. This encourages the search of more advanced solutions. Aiming to determine possible improvements, the operations of forklifts are examined in warehouses, and detail solutions are presented. For empirical study author created a simulation model and tested different scenarios. First of all, author examined the new routing method and suggested programming algorithm for forklift route optimization. In the first part of the study possible improvements for put-away activity are analysed, in the second part - improvements for replenishment activity are overviewed. Simulation results showed that the reduction of forklift travel distance is equal from 11.1% to 35.6%. Finally, the study ends with detail suggestions: author presented new routing method and forklift routing algorithm. Further, the theoretical results have to be tested in practise. [ABSTRACT FROM AUTHOR]

The paper reports findings of investigating optimal interface material parameters of product handle to improve its ergonomics by increasing the user performance, comfort, and lower the risk of cumulative trauma disorder development. Optimisation methods in combination with the finite element computer simulations of a human fingertip whilst grasping a handle were used to determine an interface foam material with optimal material properties for best mechanical behaviour of the system. A single objective function was defined to determine best material parameters of the interface foam material, which has to remain firm during low grasping forces to provide stability of the product grasp and appropriately deforms when a critical contact pressure is reached to provide higher contact area. This increases comfort and lowers the contact pressure on the hand and thereby the risk of injury development. The optimisation process yielded the optimised foam thickness and its stress-strain relationship for simulated contact of fingertip model grasping a product handle. [ABSTRACT FROM AUTHOR]

In this article we present our recent work on the simulation of a hexapod robot called PTinto. This robot is a prototype that has been designed to test the six legs locomotion system in the surrounding areas of the Tinto River (Huelva-Spain), which scientists have considered that could potentially have many similarities to the Mars surface. This kind of robots represents a great advance in the planetary research that overcomes the performance of the usual rover when operating in rocky and cumbersome areas. We are developing some of the software PTinto requires to autonomously control it and, in particular, the program that simulates its movements on any surface. Up to now we have a graphic computer program, developed in MATLAB, that represents the robot and allow us to check its movements in a lot of detail. We present in this paper all the elements and resources we use for the simulation and control of PTinto walking on irregular surfaces. Thanks to this simulation program, we could test different autonomous control strategies for the PTinto robot. [ABSTRACT FROM AUTHOR]

Project success includes time, budget, quality, customer satisfaction etc. We are always confronted with time and money in the first place. Activity schedules must consider the available resources to be completed in the right sequence and in time. Companies must maintain competitive cost-time profiles. Execution periods of non-critical project activities have a considerable influence to the amount of locked-up capital. In the paper we have simulated some cases with varied execution periods of noncritical project activities within the slack, and measured cost-time investment. For the visualisation of project cost accumulation we have applied cost-time profile; we have used Cost Time Profiler software. The results show that the differences are significant, bringing a potential for project optimization. [ABSTRACT FROM AUTHOR]

To explore the migration distribution laws of the cleaning agent of solid powder in industrial ventilation pipelines, a gas-solid flow migration model based on dense discrete phase model (DDPM) was built. Influences of various material injection methods (injection and jetting methods), positions, and directions in the narrowing zone of pipelines based on the migration laws of particulate cleaning agents in the pipelines were analysed. Results demonstrate that under the top injection method in the narrowing zone, the particulate cleaning agent presents obvious flow characteristics along the pipeline walls and cleaning agent concentration distributes unevenly in the pipelines. After the injection method is changed to top jetting, particle concentration remains high at one end near the wall and low at the other end. After changing the mouth from the top of the narrowing zone to the middle section and changing the spraying direction from perpendicular to the mainstream direction to the horizontal, the particle concentration of the cleaning agent reaches uniform distribution near the mouth and at the pipeline ends. Particle concentration in the pipelines is improved significantly. [ABSTRACT FROM AUTHOR]

For the accurate design of some types of mechanisms, it is necessary to combine multibody dynamics computer simulations with finite element structural analysis. These types of mechanisms are the multibody mechanisms in which the body (frame) stiffness of some of the bodies have the same magnitude as some of their elastic elements. With this in mind, the traditional go-kart chassis design process is reviewed. The traditional approach to evaluate the structural properties of its frame consists of an iterative process in which FEM techniques are applied considering constant load cases. These load cases are defined according to the maximum stresses to which it will be subjected during its operation (circulation in a race circuit). However, as it will be proven in this work, the load case will depend on the design of the frame itself. Due to the stiffness of the frame, for the same driving conditions (vehicle trajectory and speed) the structural load condition varies significantly. A design methodology is proposed for this type of system that combines multibody simulation and finite elements. [ABSTRACT FROM AUTHOR]

Article deals with creation of continuous simulation model of actual check-in process of selected airline based on identified decision points in passenger handling process. Case study covers actual passenger acceptance situations based on their fulfilment to ticket conditions, ticket fare, transported baggage and considering overbooking situations as planned part of airline revenue management strategy. The problem is related to the identification of bottlenecks in order to efficiently plan and use check-in counters and effectively utilize aircraft seating capacity. Case study shows importance of proper setting of check-in process, together with associated fees in case of not fulfilling ticket conditions, which helps airlines to move breakpoint to favourable percentage of load factor. Simulation models points to possibilities of restriction procedures that affects risk management and movement of breakpoint according to utilization of the aircraft and influence final revenue from the flight. The results of the computer simulation show that ticket prices range from 100.81 € to 398.14 €, the luggage weights ranges from 0.06 kg to 31.57 kg, the total revenue from ticket sales and baggage payments is 44125.8 €. [ABSTRACT FROM AUTHOR]

A systematic procedure of experiments, performing simulation in conjunction with work measurement techniques, is introduced and aimed at undergraduate students in Industrial Engineering (IE) to learn a basic procedure for designing and implementing takt production in terms of the Toyota Production Systems (TPS). Students are split into small groups in a class. A series of experiments is designed and performed for an assembly line of magnetic contactors. Using the concept of the TPS, students perform work measurement studies including time study, process design, such as line balancing, and execute simulation experiments. At the end of the course, the teaching staff evaluates each group based on the performance of the simulation results. [ABSTRACT FROM AUTHOR]

Among the technologies for middle-pressure and low-pressure energy recovery, the influence of guide vane is generally neglected in pump as turbine (PAT) based on centrifugal pumps. For high-pressure energy recovery technology, only few studies have been conducted on PAT with guide vane, and the dynamic and static flow laws between the inverse impeller and guide vanes remain unclear. In this study, by optimizing the key geometric parameters of the impeller with forward-curved blades, the influence of different parameters on its performance was investigated. Results show that when the number of blades is 10 at the same flow rate, the highest efficiency is achieved and the internal flow becomes stable. With the same number of blades, the total head increases gradually with the increase of flow rate, whereas the efficiency increases initially and then decreases. Under the same head, the PAT model with blade outlet angle achieves the highest efficiency, power and the best hydraulic performance. Conclusions obtained in this study have important value for implications to optimize the cavitation of multi-stage PAT. [ABSTRACT FROM AUTHOR]

Traditional studies simplify vehicle-track-tunnel system into vehicle-track or vehicle-tunnel models and neglect dynamics influences of vehicle on tunnel through track or track-tunnel on vehicle. This study established the mathematical model of vehicle and finite element model of track-tunnel to disclose vibration characteristics of vehicle-track-tunnel coupled dynamic system. Next, a vehicle- track-tunnel dynamic coupled model was established based on the wheel-rail displacement coordinated relation. Finally, variation laws of vehicle and stress and displacement fields of tunnel surrounding rock when the train travelled at speed of 200 km/h were studied under different track slab stiffness and track structures. Numerical simulation results demonstrate that vehicle vibration indexes change in the linear law with the increase in track slab stiffness. Sleeper embedded ballastless slab track has better damping reduction performance than sleeper buried ballastless slab track. The best damping reduction performance is achieved when the track slab stiffness is 3.5 kPa. The maximum vertical displacement and stress of the tunnel surrounding rock due to vibration at low levels and the tunnel surrounding rock slightly influence vibration indexes of vehicles. [ABSTRACT FROM AUTHOR]

Due to the higher competition in automobile industry, automotive part manufacturers who supply parts have also been challenged to improve the quality of their products to meet customers' requirements. Quality of parts or products could be controlled and improved since the stage of production process design. Efficient production process design could reduce work in process (WIP), wastes, reworks, errors, and failures, which could reduce system cost and increase quality of final products. However, production process design for the process which implements automatic systems is sophisticate due to the complication of the equipment itself and the synchronization requirement. This study presents the use of computer simulations to design an automotive part production process. Two objectives are proposed. The first one is to introduce three dimension robot (3D CAD) simulation for robotic work stations designed to meet the desired cycle time with minimum chance of robot collision and minimum number of robots in the system. The second one is to propose plant simulation for production planning design in order to produce product which could meet the desired capacity and customer needs with minimum number of workers. [ABSTRACT FROM AUTHOR]

For armoured face conveyors (AFC) in coal mines, fracture and jam phenomena of the chain are common failure patterns in the chain assembly. These failure patterns are caused by chain's severe vibrations from uneven loads on the conveyor. However, due to limitations of harsh operating environment in coal mines, performing underground experiments is difficult to obtain real vibration signals. Multi-body dynamic simulation is an efficient approach to analyse the complex dynamic behaviour of chain assembly in the AFC. In order to determine the actual dynamic properties of chain assembly in the AFC under different operating conditions, multi-body simulation was used to analyse the vibration properties of the chain assembly. In this study, theoretical analysis of contact force between horizontal and vertical rings, and between sprocket wheel and rings in the chain assembly was initially performed. Rigid and rigid-flexible coupling models of the chain assembly were then established. Dynamic simulations through two types of models, that is, rigid and rigid-flexible coupling models were conducted under full-, half- and empty load conditions using the ADAMS software. Trends of contact force, stress, and velocity of horizontal and vertical rings under various working conditions were obtained, and vibration properties of the chain assembly were analysed based on the corresponding curves. Results indicate that the maximum velocity is 1.75 m/s in the rigid simulation, whereas the maximum velocity is 3.0 m/s in the rigid-flexible coupling simulation. The rigid-flexible coupling method is proven to be more accurate and feasible in describing the dynamic properties of the chain assembly than the rigid method. The proposed method should be preferentially utilized in performing multi-body dynamic simulation of the chain assembly in the AFC. This study provides references for the structural optimization and design of the chain assembly in mining AFC. [ABSTRACT FROM AUTHOR]

The article deals with the use of computer simulation approach in order to streamline production logistics within a specific production company. The computer simulation from its very beginnings has undergone a long and significant evolution. The current possibilities of computer simulation approach enable to mimic the real processes of production logistic activities as well as of the actual production. This article is focused on the question, how to effectively utilise the available tools of computer simulation approach to analyse and streamline a particular simulation system. Therefore also the presented solution is the actual description of a practical application of a computer simulation approach used for the needs of one specific production company within one specific industry area. The intention is to showcase the practical aspects of simulation modelling, in this case utilising the EXTENDSIM simulation system. The simulation approach will be used for the needs of a production company, that produces car components and accessories made of wood for the automotive industry. [ABSTRACT FROM AUTHOR]

The spur gear mechanism with the standard involute profile may generate noise and shock because of tooth structure and transmission principle, resulting in substantial transmission errors. These limitations can be effectively resolved through tooth profile modification. To address the defects and deficiencies of existing tooth profile modification methods in terms of the modification principle and effect assessment, this study proposes an adaptive method of tooth profile modification with alterable tooth profile for spur gear mechanism. A corresponding simulation method for evaluating the modification performance of the gear transmission was introduced in detail. The final shape parameters of the modification profile were determined by orthogonal experiments. Simulation results show that tooth profile modification for involute spur gear does not affect bending and contact stresses. The process can also effectively improve the stability of transmission. The impact and noise of gear pair with tooth profile modification significantly decreased during meshing. The proposed method exhibits stronger adaptability compared with other existing methods of tooth profile modification. Moreover, the proposed method can adaptively determine the optimal modification parameters based on different conditions and obtain the ideal modification effect. [ABSTRACT FROM AUTHOR]

Unmanned surface vehicle (USV) is an important autonomous marine vehicle. The safe navigation of USV is directly determined by the local obstacle avoidance because it must avoid real-time local obstacle in the global path planning in a three-dimensional environment. Therefore, efficient algorithms of real-time local obstacle avoidance for USV are a critical issue. In this study, a new threelayered architecture for local obstacle avoidance algorithm was proposed to solve the local obstacle avoidance problem. First, real environment and obstacle models were established in the polar coordinate. The known static path-planning method was conducted based on particle swarm optimization (PSO). Second, the method was integrated with marine rules based on PSO. Third, an obstacle avoidance method under unknown environment was created based on rolling windows. Finally, a simulation experimental platform was developed to verify the feasibility and effectiveness of the aforementioned measure. Result shows that the proposed algorithm can effectively avoid local obstacles of USV at a computation time of less than 2 s. The USV avoids the obstacles smoothly and reaches the desired destination with complex requirements. The simulation results also demonstrate the promising application of the proposed method in studying the path planning of USV. This method can address the issues of real-time local obstacle avoidance of USV. [ABSTRACT FROM AUTHOR]

Connectionism strategy is widely used by the policymaker to implement the emergency rescue activities in industrial accidents, exploring its mechanism is helpful to deeply understand the mechanism of behavioural change of policymakers during emergency decision-making procedure. In this study, the emergency process and influential factors as well as three types of emergency disposal schemes, when the connectionism strategy was adopted for rescue activities in coal mining accidents, were qualitatively analysed and concluded. Then, an improved simulation model was proposed based on Parallel Constraint Satisfaction (PCS) model. Lastly an algorithm written in MATLAB was employed to model and explore the influential mechanism of the negative emotion and the concern of policymakers as well as the mode of decision-making tasks on decision time and decision confidence. Results demonstrate that, the higher the policymakers' negative emotion, the shorter the decision time and the higher level of decision confidence they have. Under different modes of decision tasks, the more difficult it is to identify the superiority and inferiority of different disposal schemes, the more decision time the policymakers need and the lower level of decision confidence they have, the decision confidence is more sensitive to the mode of decision-making task, meanwhile the negative emotion and the concern of policymakers have different effects on decision time and decision confidence. Compared with the concern on cues, policymakers' decision confidence is much higher when they focus more on schemes. The study reveals the mechanism of connectionism strategy adopted for emergency rescue activities in industrial accidents, which has a profound significance for optimizing emergency decision support systems for industrial accident management and enhancing the quality of emergency decision-making. [ABSTRACT FROM AUTHOR]

In order to solve the problem of inadequate penetration of low-density jet penetrating shell charge, the low-density PTFE are modified by adding a certain fraction of copper powder in the matrix. This treatment helps to increase the material density and jet energy, as well as to improve the static and dynamic mechanical properties of the material. AUTODYN-2D finite element software is used to simulate the process in which the low-density jet forms and penetrates shell charge. The simulation and experiment results show that in comparison to PTFE, the mechanical properties of PTFE/Cu have been significantly improved, and the jet has strong penetration capability. Under the same structural conditions, the penetration diameter of PTFE/Cu jet is about enhanced by 70 % for the panel and 30 % for the back plate compared to that of PTFE jet. As an experimental result, the penetration depth of the main armour by PTFE/Cu jet is enhanced by 5.38 % compared with that of PTFE jet. [ABSTRACT FROM AUTHOR]