Davorin Kofjač

The anticipative concept in warehouse optimization using simulation in an uncertain environment

The modern business environment is highly unpredictable. An anticipation approach in a real case study is presented to cope with such instability and minimize the total inventory cost without stock-outs occurring and inventory capacity being exceeded. The anticipation concept is performed using simulation models supported by inventory control algorithms on a selected sample of representative items. The inventory control algorithms include Silver-Meal, Part period balancing, Least-unit cost, and Fuzzy inventory control algorithm based on fuzzy stock-outs, highest inventory level and total cost. Transportation cost is explicitly defined as a discrete function of shipment size. The algorithms are tested on historic data. Simulation results are presented and the risk of accepting them as reliable is discussed. The process of simulation model implementation is briefly discussed to further validate the model and train order managers to use the simulation model in their order placement process.

Speech-controlled cloud-based wheelchair platform for disabled persons

This paper describes the development of the prototype speech controlled cloud based wheelchair platform. The control of the platform is implemented using low-cost available speech WebKit in the cloud. Besides the voice control, the GUI is implemented which works in the web browser as well as on the mobile devices providing live video stream. The platform is based on Mini PC running Ubuntu Linux and Arduino UNO Microcontroller. Software development was done in JavaScript / ECMA Script.

Prototype of speech controlled cloud based wheelchair platform for disabled persons

This paper describes the development of the prototype speech controlled cloud based wheelchair platform. The control of the platform is implemented using low-cost available speech WebKit in the cloud. Besides the voice control, the GUI is implemented which works in the web browser as well as on the mobile devices providing live video stream. The platform is based on Mini PC running Ubuntu Linux and Arduino UNO Microcontroller. Software development was done in JavaScript / ECMA Script.

Determination of recruitment and transition strategies

Purpose – This paper aims to describe the development and application of a manpower planning system for the Slovenian armed forces using a system approach, system dynamics (SD) and numerical optimization.Design/methodology/approach – The model of the hierarchical manpower system was developed by SD methodology and formulated in discrete time space. The problem of tracking the goal trajectories in the eight topmost ranks at the prescribed boundaries was solved by application of the quadratic performance index and finite automata (FA) which was used for classification of acceptable strategies. Genetic algorithms (GA) as well as pattern search were compared at the numeric optimization.Findings – Employing SD and a system approach increases the understanding of the system control. The definition of an optimum strategy, which would consider only target values for ranks within prescribed parameter boundaries, could provide an undesired oscillatory solution. Inclusion of rules by FA to determine acceptable strat...

A proposed simulation-based operational policy for cruise ships in the port of Kotor

This paper investigates the simulation modelling of cruise ship traffic in the Boka Kotorska Bay (BKB), which has become a very attractive cruise destination due to its geographic location, port features and attractiveness for tourism. The purpose of this paper is to examine the development of new port infrastructure, because of the increased cruise ship arrivals in recent years. The paper describes in detail the layout of the port of Kotor and the possibilities for quay extensions. The solution to minimize the number of ships at anchorage instead of being at berth is given, because the passengers of the latter ships have a more convenient approach towards the port. The simulation model is verified and the simulation results are validated against the real data prior to an investigation of the possible scenario for quay extension. The proposed solution confirms the preliminary survey results that initiated the investigation of possibilities to improve the port infrastructure. Moreover, simulation results point towards a significant improvement of cruise ships throughput in the BKB. The proposed operational policies and statistical analysis, as well as a comprehensive model analysis of the BKB provided here, are a good foundation for future investigations.

Streaming pulse data to the cloud with bluetooth LE or NODEMCU ESP8266

The paper describes the development of the three prototypes which enable monitoring of heart pulse sensor data on the cloud. The prototypes are based on a) Bluetooth module, b) Low Energy Bluetooth module and c) ESP8266 Wi-Fi module. The client side implementation is developed by the application of JavaScript. Node.js was used on the server side with application of node-serialport library with Bluetooth modules. In the case where ESP8266 Wi-Fi module was used, the data was transmitted directly to the cloud. The three different prototypes were compared according to the power consumption and complexity of design. The code example is provided illustrating the approach to develop cloud based graphing interface for biomedical mobile monitoring.

Wheelchair maneuvering using leap motion controller and cloud based speech control: Prototype realization

The paper describes the development of prototype wheelchair platform controlled by the gestures. Leap Motion Controller is used to acquire data while changing the hand position. The novel user interface was developed, which shows the hand position to the user and combines the classical button GUI switchboard. The developed system is cloud based and integrates speech recognition to engage the motion controller as well as to control the entire platform if needed. The entire software was developed with JavaScript/ECMA Script.

Adaptive fuzzy inventory control algorithm for replenishment process optimization in an uncertain environment

This paper presents a real case study of warehouse replenishment process optimization on a selected sample of representative materials. Optimization is performed with simulation model supported by inventory control algorithms. The adaptive fuzzy inventory control algorithm based on fuzzy stock-outs, highest stock level and total cost is introduced. The algorithm is tested and compared to the simulation results of the actual warehouse process and classic inventory control algorithms such as Least-unit cost, Part period balancing and Silver-Meal algorithm. The algorithms are tested on historic data and assessed using the Fuzzy Strategy Assessor (FSA). Simulation results are presented and advantages of fuzzy inventory control algorithm are discussed.

Development of a Web Application for Dynamic Production Scheduling in Small and Medium Enterprises

Development of a Web Application for Dynamic Production Scheduling in Small and Medium Enterprises This article describes the development of a web-based dynamic job-shop scheduling system for small and medium enterprises. In large enterprises, scheduling is mainly performed with appropriate technology by human experts; many small and medium enterprises lack the resources to implement such a task. The main objective was to develop a cost-effective, efficient solution for job-shop scheduling in small and medium enterprises with an emphasis on accessibility, platform independence and ease of use. For these reasons, we decided to develop a web-based solution with the main emphasis on the development of an intelligent and dynamic user interface. The solution is built upon modular programming principles and enables dynamic scheduling on the basis of artificial intelligence, i.e. genetic algorithms. The solution has been developed as a standalone information system, which allows the management of virtually all scheduling activities through an administration panel. In addition, the solution covers the five main functionalities that completely support the scheduling process, i.e. making an inventory of resources available in the company, using it in the process of production planning, collecting data on production activities, distribution of up-to-date information and insight over events in the system.

Prototype of group heart rate monitoring with NODEMCU ESP8266

Paper describes the development of prototype that enables monitoring of heart rate and inter beat interval for several subjects. The prototype was realized using ESP8266 hardware modules, WebSocket library, nodejs and JavaScript. System architecture is described where nodejs server acts as the signal processing and GUI code provider for clients. Signal processing algorithm was implemented in JavaScript. Application GUI is presented which can be used on mobile devices. Several important parts of the code are described which illustrate the communication between ESP8266 modules, server and clients. Developed prototype shows one of the possible realizations of group monitoring of biomedical data.