Višekriterijsko adaptivno oblikovanje planova pokusa

Prilikom odabira modela planova pokusa, što je važna faza u većini znanstvenih istraživanja, potrebno je voditi računa o adekvatnosti modela, obliku rezultata koji se žele dobiti, te preciznosti modela odnosno pogrešci koja se nužno pojavljuje. Budući da se područje planova pokusa počelo razvijati, pa tako i uporabljati, u vrijeme kada je njihovom uporabom ostvarena velika ušteda u resursima, nije se dovoljno istražila mogućnost minimiziranja ostalih parametara eksperimentiranja kao što su cijena, utrošeno vrijeme i sl. Općenito se može reći da se vrlo malo istraživanja u literaturi odnosi na spomenuti problem. Istraživanje će se, u ovom radu, odnositi na razvoj metodologije i modela koji će biti potpora pri izboru i konačnom oblikovanju planova pokusa. Cilj je istražiti odnos pogreške pokusa odabranog modela (preciznost), troškova realizacije pokusa, te vremena potrebnog za eksperimentiranje. \Novorazvijeni model, koji predstavlja rezultat ovih istraživanja, trebao bi omogućiti pronalaženje optimalnih planova pokusa sa stajališta novouvedenih kriterija optimalnosti

Optimisation of Parameters for Metal Part Cutting on a CNC Plasma Cutting Machine

This paper refers to the topic of determining the kerf value and axis accuracy of a CNC plasma cutter for the cutting of 2, 4 and 6 mm thick plates of construction steel, aluminum and stainless steel. After the thorough description of the researched materials, a detailed experiment plan was created in the Design-Expert software package. After cutting the test samples the data were measured. Upon completion of the cutting, all test samples were measured, and the data regarding their dimensional deviations on x and y-axis and bore diameter deviations was tabularly shown and analysed with the Design – Expert software. Statistical analysis of the measured data was made so that the optimal kerf values and the equations which describe dimensional deviations for each material and thickness could be made, based on the dimensional deviation of the test samples. Along with the kerf values, analysis has also given insight in the accuracy of the x and y-axis of the machine. Finally, an algorithm for optimizing multiple criteria was utilized to determine the ideal kerf value for each material and thickness. The objective was to identify the precise kerf value that results in the highest possible accuracy for the dimensions of the workpiece in both the x and y directions, as well as for the bore diameter

Green supply chain management in Croatian companies

The scope of this paper is to present current state and trends of Green Supply Chain Management (GSCM) in Croatian companies. Due to the need for reduction of GHG emissions related to the climate change, many standards, directives, concepts, methods and models dealing with sustainability have appeared. The first part of the paper consists of an overview of GSCM where the greening diagram of GSCM is presented. The second part of the paper presents the survey which has been carried out in the Croatian business sector in view of current state and trends, barriers and drivers of the GSCM implementation. According to the results of the survey, barriers and drivers of the GSCM implementation are ranked by its significance and are compared with similar surveys carried out in the European Union (EU) and the United States of America (USA). New categorization of the drivers of the GSCM implementation is presented using the factor analysis

IMPROVABILITY OF THE FABRICATION LINE IN A SHIPYARD

The ship production process is a complex manufacturing system involving numerous working stations mutually interconnected by transport devices and buffers. Such a production system can be efficiently modeled using the stochastic system approach and Markov chains. Once formulated, the mathematical model enables analysis of the governing production system properties like the production rate, work-in-process, and probabilities of machine blockage and starvation that govern the production system bottleneck identification and its continuous improvement. Although the continuous improvement of the production system is a well-known issue, it is usually based on managerial intuition or more complex discrete event simulation yielding sub-optimal results. Therefore, a semi-analytical procedure for the improvability analysis using the Markov chain framework is presented in this paper in the case of the shipyard’s fabrication lines. Potential benefits for the shipyards are pointed out as the main gain of the improvability analysis

Difference and similarity in perception between Green Supply Chain Management in food industry and Green Supply Chain Management in generally in Croatian companies

Nowadays, the increase in greenhouse gas (GHG) emissions in the atmosphere is currently one of the most serious environmental treats. Due to GHG emissions we will be witnesses of climate change which will cause damaging impacts in the next few decades [1]. These will primarily affect the natural and human systems [2]. At the same time these emissions are also a limiting factor for the economic growth of some countries, especially those in the transition process [3]. One of the reasons for that is the protocol, adopted in 2012 at Doha 2012 UN Climate Change Conference COP18 CMP8, at which the industrial world agreed to reduce the emissions of greenhouse gases approximately 18% below 1990 levels by 2013-2020 [4]. In the meantime, also due to the climate change and the increase in environmental awareness all over the world, the concept of Green Supply Chain Management appeared. It is often defined as integrating environmental thinking into supply chain management [5].Within that concept many greening elements aimed at the reduction of materials, energy, waste, pollution and emissions, or promoting the usage of recyclable materials and renewable energy sources, are introduced in various segments of supply chains. The proof lies in number of examples from industry, as well as in significant interest of academic community that could be seen through research papers, doctoral thesis and research projects.[...

Solving Problems of Interruptions and Multitasking in the Pharmacy of a Large Hospital Centre

This paper presents an approach to solving problems of interruptions and multitasking in inpatient pharmacy processes of a large hospital centre, which is based on statistical modelling and simulations. The approach is applied to the process of receiving deliveries (from suppliers) to determine the feasibility of improvements in the organization of work. In the initial phase of research, data on the deliveries from suppliers were collected during the time study and a typical daily load on the pharmacy staff and infrastructure in the current state was simulated. Subsequently, a new organizational model, which included two defined blocks of time for delivery, was suggested and three simulation scenarios were created to examine the effects of new organization of work on daily activities. Finally, a comparison of system constraints and results obtained by the simulation models confirmed the feasibility of the proposed improvements. By implementing the new organization of work, it will be possible to avoid overlapping in pharmacy processes, which will reduce interruptions to work and the need for multitasking and will finally result in fewer errors in work