Mihael Gudlin, Miro Hegedić, Hrvoje Cajner, Nedeljko Štefanić: 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.

Key words: inpatient pharmacy; process improvement; statistical modelling and simulation; supplier arrivals; goods receiving process.

Raheleh Nowzari: Numerical Analysis of a Photovoltaic Module Integrated with Various Water Cooling Systems

As the main drawback of a photovoltaic module is its high operating temperature, various designs for cooling the module are presented in this study. Computational fluid dynamics (CFD) software is used for simulating the presented models. In these models, water channels are placed above or below the panel to cool the module and heat the water at the same time. In two designs, aluminium fins are attached to the bottom side of the panel inside the water channel. The water outlet temperature, pressure drop and heat flux from the panel are calculated at various Reynolds numbers. The results show that as the Reynolds number increases, the heat flux and the pressure drop increase while the coolant average outlet temperature decreases. The highest amount of heat flux is obtained from Model A, which indicates that this model has a better cooling capacity than other models investigated in the study.

Key words: Photovoltaic panel; numerical analysis; ANSYS; cooling channels

Franz Haas, Andres Suárez, Franci Cus, Uros Zuperl: Platform for Monitoring and Comparing Machining Processes in Terms of Energy Efficiency

This paper presents a smart energy consumption monitoring platform for machining processes with a unique electrical energy consumption indicator (EECI) for the evaluation and comparison of machining processes in terms of energy efficiency. The purpose of the developed smart monitoring platform with the integrated EECI and the Industry 4.0 digital technologies is to raise the level of efficiency of the machining process and thus to stimulate more sustainable and environmentally friendly machining. The energy consumption monitoring of a milling process is performed by connecting a machine tool with integrated sensors for measuring electrical power and cutting force to a cloud platform by using resources for signal acquiring and data acquisition. The platform includes applications for energy consumption monitoring and/or analysis. Results of four machining experiments are presented to demonstrate the effectiveness of the proposed energy consumption monitoring in machining and the applicability of the newly introduced EECI at the engineering and the operational level.

Key words: machining; milling; energy efficiency; smart monitoring; electrical energy consumption indicator

Zhiquan Liu: Ship Course Keeping Using Different Sliding Mode Controllers

This study addresses three sliding mode heading controllers for dealing with uncertain wave disturbances. A nonlinear steering model is derived, and the feedback linearization method is chosen to simplify the nonlinear system in this study. The adaptive method and disturbance observer technique are proposed for course keeping and ensuring robust performance of the time varying wave moment and actuator dynamics. Finally, the simulation results on a navy ship illustrate the effectiveness of the presented control algorithms for course keeping.

Key words: sliding mode control; course keeping; adaptive control: nonlinear disturbance observer

Lakshminarayanan Varadha Rajan, Velmurugan Pavanan, Karthikeyan Palaniswamy: Interdigitated Flow Channel on a Proton Exchange Membrane Fuel Cell Investigated Using the Response Surface Methodology

Performance of the proton exchange membrane (PEM) fuel cell depends on the operating pressure, operating temperature, stoichiometric ratio of reactant gases, relative humidity, and rib width-to-channel width ratio (R:C), shape of the flow channel, and the number of passes on the flow channel. The effect of pressure, temperature, inlet reactant mass flow rate and rib width-to-channel width ratios of 1:1, 1:2, 2:1, and 2:2 on the power density of a PEM fuel cell with interdigitated flow channel of 25 cm^2 active area of was considered in this study. The response surface methodology was used for optimizing the four above mentioned parameters to find the optimum power density of the PEM fuel cell. The analysis of variance (ANOVA) was used to find the contribution of each parameter to the performance of the PEM fuel cell. Further, numerical results were compared with the experimental validation of the PEM fuel cell. Numerical results of power densities of interdigitated flow channel with R:C ratios of 1:1, 1:2, 2:1, and 2:2 were found to be 0.272, 0.292, 0.267, and 0.281 W/cm^2 and the corresponding experimental results of power density were 0.261, 0.266, 0.254, and 0.264 W/cm^2, respectively.

Key words: Optimization; PEM fuel cell; response surface methodology; computational fluid dynamics; interdigitated flow channel; rib width-to-channel width ratio

Christian Bischof, Daniela Wilfinger: Big Data-Enhanced Risk Management

Today’s global and complex supply networks are susceptible to a broad variety of internal and external risks. Thus, comprehensive and innovative approaches to risk management are required. This paper addresses the question of how Big Data can be used for the implementation of an advanced risk management system. A conceptual framework covering three major dimensions of Big Data-driven risk management, i.e. type of risk, risk management phases and available technology, is introduced. Additionally, selected application examples for early detection, assessment, mitigation and prevention of risks in supply networks are provided.

Key words: Risk Management; Supply Networks; Digitalisation; Big Data

İsmail Tekaüt: Theoretical Evaluation of the Effect of Surfaces Processed with Abrasive Water Jet on Fatigue Life

Surface roughness is an effective factor in determining the fatigue life of machine elements. Roughness of the surface results in the notch effect, and if the notch effect increases, the fatigue life of the material is shortened. 20 mm thick steel AISI 1050 (CK45, DIN 1.0540, EN C50) was cut into 80×80 mm squares by applying the abrasive water jet machining technique. The square cutting operations were carried out at five different feed rates (10, 16, 24, 34 and 45 mm/min) and the other cutting parameters were kept constant. The Rz and Sm surface roughness values of the four surfaces obtained at each feed rate were measured. The effect of the feed rates on the surface roughness was investigated. Also, by applying the Murakami surface roughness fatigue model, the effects on the theoretical fatigue life of the surface roughness resulting from the chosen feed rates were modelled. Furthermore, the reason for the difference in surface roughness values between the first, the second, the third and the fourth surface at each feed rate was investigated. As a result, an increase in the feed rate causes an increase in surface roughness values, which in turn shortens the fatigue life of the material. The surface roughness value measured on the first surface of the four cutting surfaces obtained at the same feed rate increases on each surface and reaches the highest value on the fourth surface.

Key words: abrasive water jet; AISI 1050 tool steel; surface roughness; fatigue

In memoriam, Nekrolog: In Memoriam Ksenija Horvatić-Baldasar, PhD, retired associate professor

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