Krešimir Osman | University of Zagreb (original) (raw)

Papers by Krešimir Osman

The objective of the research presented in this paper is to develop an algorithm for predicting b... more The objective of the research presented in this paper is to develop an algorithm for predicting behaviour of complex technical systems in an uncertain working environment. System’s dynamic behaviour modelling and simulation should help to develop new and improve existing architectures of complex technical systems by mapping in both directions, from the structural to the behavioural domain and vice versa. The algorithm for predicting behaviour during system’s architecture development consists of several operations shortly described in this paper. The proposed algorithm was verified on an example of a complex technical system – an air-handling unit.

Thermal science journal

This paper aims to develop a testing methodology to evaluate measurement uncertainty of thermosta... more This paper aims to develop a testing methodology to evaluate measurement uncertainty of thermostatic chamber temperature field in thermal processing of semi-durable meat product in the meat industry. The proposed testing methodology qualitatively evaluates the working space of the thermostatic test chamber, including the following tested influential parameters: mass of a product in a batch, thermal processing temperature, temperature in the geometric center of a product after shower cooling, duration of thermal processing, spatial temperature gradients, spatial temperature stability, heating and cooling dynamics between two temperature working points, and temperature measurement uncertainty. As many practical technical issues arose, we conducted an analysis of the impact of input test parameters by using the response surface method to predict the unknown values of predefined output parameters on the basis of known values of influential input parameters, and to actually rank each resulting impact of each input test parameter. The proposed testing methodology is in accordance with the International Standard IEC 60068-3-5 and the French Norm NF X 15-140.

The International Scientific Journal of Management Information Systems - accepted for publication

The research objective in this paper was developing web based group decision support system, wher... more The research objective in this paper was developing web based group decision support system, where is using multi attribute approach based on fuzzy AHP method to evaluate alternatives, and selecting the best one. This system allows decision makers distributed in different locations to participate in a group decision-making activity through the web. The method used here must enable to choose which alternative in a finite selection is best suited in terms of the overall target. Various priorities should be allowed for in defining the overall target. This method must not only take the intended targets into consideration, it also has to allow for a large number of different criteria, which are included in the decision making process by devising a system of characteristic values. The resulting complexity of the assessment task calls for approach which, on the other hand, makes it possible to apply a weighting profile to the individual part-targets, thereby allowing us to switch our priorities around, but which also ensures that very varied criteria are taken into consideration. Since the AHP approach can manage complexity, while fuzzy logic allows handling uncertainty, the proposed method combines these techniques in an integrated approach.

Thermal Science Journal - accepted for publication

The thermodynamic analysis demonstrates the feasibility of replacing the standard ammonia refrige... more The thermodynamic analysis demonstrates the feasibility of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry. The main reason for replacement is to reduce the total amount of ammonia in spaces like deep-freezing chambers, daily chambers, working rooms and technical passageways. An ammonia-contaminated area is hazardous to human health and the safety of food products. Therefore the preferred reduced amount of ammonia is accumulated in the Central Refrigeration Engine Room, where the cascade NH3/CO2 device is installed as well. Furthermore, the analysis discusses and compares two left Carnots refrigeration cycles, one for the standard ammonia device and the other for the cascade NH3/CO2 device. Both cycles are processes with two-stage compression and two-stage throttling. The thermodynamic analysis demonstrates that the selected refrigeration cycle is the most cost-effective process because it provides the best numerical values for the total refrigeration factor with respect to the observed refrigeration cycle. The chief analyzed influential parameters of the cascade device are: total refrigeration load, total reactive power, mean temperature of the heat exchanger and condensing temperature of the low-temperature part.

Proceedings of the 13th International Design Conference DESIGN 2014

The objective of the research presented in this paper is to develop an approach modeling and pred... more The objective of the research presented in this paper is to develop an approach modeling and predicting the nonlinear behaviour of complex technical systems in the operating environment, based on a presentation of the system’s dynamic behaviour and recording of such behaviour by using the rules. This approach should help develop new architectures of nonlinear complex systems and improve existing ones, by mapping in both directions, from the structural to the behavioural domain and vice versa. Verification of this approach is presented on the example of a load lifting device.

International Journal for Traffic and Transport Engineering (IJTTE) (2217-544X) 4 (2014), 1; 90-102

"This paper presents the development of the MOTORI 2004 computing tool that calculates the distan... more "This paper presents the development of the MOTORI 2004 computing tool that calculates the distance, speed and acceleration of a car engine valve train’s oscillating mass m,
which is reduced to the valve axis. Distance diagrams, speed and accelerations are provided in dependence on the camshaft twist angle at a constant rotational speed in several consecutive
revolutions. The computing tool implements a mathematical description and numerical solution for the motion of mass m of a valve gear dynamic model. Valve lift h is given numerically using
a series of equidistant points in the period of one camshaft revolution. The variabilities of camshaft rotation and spring thread vibration as a result of cam lift harmonic excitation. The computing solutions were tested at valve opening points and in imaginary extreme operating conditions (soft/hard spring, low/high damping, low/high rotational speed and increased clearance."

22nd International Symposium and Exhibition on Heating, Refrigerating and Air Conditioning; 11th Conference on Thermography

Rad prikazuje pristup u poboljšanju sustava upravljanja u postrojenju klimatizacije poslovnog obj... more Rad prikazuje pristup u poboljšanju sustava upravljanja u postrojenju klimatizacije poslovnog objekta. Prvo je opisan i prikazan postojeći sustav upravljanja, sa pripadnim matematičkim modelima procesa u postrojenju, uz opis postojećih uvjeta upravljanja. Slijedi analiza postojećih algoritama upravljanja tokom zimskog i ljetnog režima rada. Postojeći sustav upravljanja počiva na načelu kaskadne regulacije, izvedenog sa PI i PID regulatorima. Istraživanje navodi nedostatke koji su uočeni na njemu, te daje prijedlog njegovog poboljšanja. Dana je izvedba poboljšanja sustava upravljanja, koja je izvedena kao sustav sa spregnutim procesima sa PID regulatorima. Za postojeći sustav, kao i za njegovo poboljšanje, u danim režimima rada, prikazana je simulacija u programu MATLAB® Simulink®. Na kraju rada, dana je diskusija s obzirom na dobivene rezultate simulacije, te zaključak sa prijedlozima mogućnosti daljnjeg istraživanja.

Chemical industry 67 (2013), 5; 759-771

The complexity of mechatronic products such as climate chamber subsystems results in enormous dif... more The complexity of mechatronic products such as climate chamber subsystems results in enormous difficulties in understanding where the main design process inefficiencies are. It is therefore extremely difficult to determine which improvements will have the most significant impact on a company or on a specific project. Mechatronic products are characterized by a high level of interdisciplinarity and complexity in the technical system and the relevant development processes. The main challenge in this respect is how to deal with the high complexity of and a variety of interdependencies in such products. We are therefore presenting a framework for integrated mechatronic product and process modelling – extended M-FBFP framework. This framework provides different independent perspectives of the overall product to improve their architecture. As a result of the proposed framework, risk analysis through subsystems in the components domain and through processes in the technical processes domain is enabled and it is now possible to provide feedback on product architecture. To obtain optimally robust product architectures from available alternative solutions, an evaluation analysis was performed across all stages, including the initialization and subsequent refinements with several evaluation criteria: complexity, interdependency and process duration. To test the validity of the proposed framework, we are presenting a case study involving a climate chamber with heat regeneration.

Design for X - Beiträge zum 23. DfX-Symposium / Krause, Dieter ; Paetzold, Kristin ; Wartzack, Sandro (Hrsg.) (ur.). - Hamburg : TuTech Innovation GmbH , 2012. 249-261 (ISBN: 978-3-941492-51-6)

This paper proposes a matrix based approach with aim to help mechanical designers tackle the prob... more This paper proposes a matrix based approach with aim to help mechanical designers tackle the problem of risk emerging in assessing product architecture under the uncertain operating conditions in early design stages. The presented approach combines existing matrix based methods - Quality Function Deployment (QFD) and Multiple-Domain Matrix (MDM) methods with the Function-Based Failure Propagation (FBFP) method. The QFD method is an integrated set of tools for recording user requirements, engineering characteristics that satisfy these requirements, and any trade-offs that might be necessary between the engineering characteristics, while the MDM method is applied to model structural arrangements and dependencies between the domains and within themselves. The FBFP method is applied at the functional level providing information of potential failure based on product functions during conceptual design in product subsystems. As a result of the proposed approach, risk analysis of subsystems becomes possible and feedback on structural analysis of product architecture could be provided. To obtain the optimum robust product architectures from available alternative solutions a continuous risk analysis of the system is proposed. The analysis is performed through all stages from initialization through later refinements with several evaluation criteria: complexity, interdependency and process duration. The following section presents the background of this research, related work and research motivation. Third section will provide more detailed description of proposed matrix based approach. Fourth section four will provide to evaluate and test validity of the proposed matrix approach. A real case study will be presented here. Conclusions and future research close this paper.

FME Transactions (2011) 39(4), pp. 145-156

"This paper proposes an M-FBFP framework with the objective to help designers tackle the problem ... more "This paper proposes an M-FBFP framework with the objective to help designers tackle the problem of risk emerging from product architecture and the effects of uncertain operating conditions. The proposed framework combines matrix approaches (QFD and MDM) and the FBFP method. The QFD is an integrated set of tools for recording user requirements, engineering characteristics that satisfy these requirements, and any tradeoffs that might be necessary between the engineering characteristics, while the MDM is applied to model structural arrangements and dependencies between the domains and within themselves. The FBFP method, on the other hand, is applied at the functional level, provides potential failure information based on product functions during conceptual design in product subsystems. As a result of the proposed framework, risk analysis of subsystems becomes possible and feedback on product architecture could be provided. To test validity of the proposed approach, here is presented a case study with climate chamber with heat regeneration."

The master thesis describes an air conditioning facility and the patterns of the process and its ... more The master thesis describes an air conditioning facility and the patterns of the process and its sub-processes during the winter and summer operating modes. A brief review of the research area associated with literature about the controlling algorithms used in the control system, the PI and PID controllers, is followed by a description of all devices and processes in it with work decription od air-conditioning facility. Based on the analysis of the physical patterns of the processes, the mathematical models of all processes were established for the air conditioning facility with concentrated parameters. a description of the existing condition of the control system, including a analysis of existing system and control algorithms in the system, during the winter and summer operating modes. The existing control system relies on the principle of cascade control. It also includes a simulation of the existing control system in the winter and summer operating modes in the MATLAB® Simulink® program. The thesis specifies the deficiencies detected on the existing control system and provides a proposal for improvement of them. This is followed by a version of an improved control system, provided as a system with coupling processes with PID controllers.
The thesis also includes a simulation of the improved control system in the winter and summer operating modes in the MATLAB® Simulink® program and a discussion concerning the simulation results obtained. In addition, it is given a description and a list of the measuring and control equipment that would be incorporated into an improved control system.

Configuration matrices are used in the development of products for the documentation of modular p... more Configuration matrices are used in the development of products for the documentation of modular product structures. They represent a visual tool for managing configuration knowledge changes, so it can be said that configuration knowledge changes concurrently with the impact of product development on existing products. The presentation of knowledge via such matrices facilitates the management of configuration rules in environment changes. We attempted to provide a presentation that would be easily comprehensible and adapted to human abilities.
In addition to matrices, the paper also presents a matrix-based configurator and its design.

Applied Mechanics and …, Jan 1, 2012

This paper proposes a Behaviour Prediction Framework with an objective to help designers tackling... more This paper proposes a Behaviour Prediction Framework with an objective to help designers tackling the problem of uncertainty emerging from system architecture and the effects of the uncertain operating conditions. The proposed framework combines structural and dynamic system model. The Design Structure Matrix is applied to model structural arrangements and dependencies between the subsystems. The Model Predictive Control is applied to model the system in discrete and continuous dynamic domains. As the result of the proposed framework, stability analysis of subsystems in interaction become possible and feedback on system architecture could be provided. To test validity of the proposed approach, the test case involving climate chamber with heat regeneration is presented.

Proceedings of the 11th International …, Jan 1, 2010

This paper describes the application of two methods, and the proposed framework, with which we wa... more This paper describes the application of two methods, and the proposed framework, with which we want to achieve optimal choice platform products, combining the following methods: Modular Function Deployment (MFD) (my previous work) and evaluation using of multicriteria decision making process, based on the method of Analytic Hierarchy Process (AHP). Here we applied computer tools “SuperDecisions” for creating a hierarchical model of AHP decision making. With this work we want to improve and accelerate the development of product platform (in this case on the example of cooling generator with air-cooled condenser with axial fan and for outdoor position of installation).

Proceedings of the DESIGN 2008, …, Jan 1, 2008

This paper aims to contribute to the understanding of the roles of module, modularity and modular... more This paper aims to contribute to the understanding of the roles of module, modularity and modularization. This paper’ s objective is to propose engineering methods for more rational engineering activities base on the idea of modularization and design for reuse. The basic goal of the research is to help the designer in the conception and design of a design solution, reduce the time of preparation of design documents, and thus reduce the overall product development costs. In this paper it is need to research possibility of development cooling generator product family based on modular architecture. For this purpose it is used Modular Function Deployment method [Erixon, 1998.], consisting of five main steps and which describe structuring products in modules. The method analyzes the functional requirements for a product and determines the technical solution and modular concept, and consists of the following steps: clarify customer requirements, technical solutions, define possible modules, evaluate concepts and improve each module.

The 8th International Symposium Power and Process …, Jan 1, 2008

The existing and planned residential construction, accompanying construction and other constructi... more The existing and planned residential construction, accompanying construction and other constructions require constant and efficient supply of heat. This requirement may be fulfilled by building a connecting heat pipeline running from the facility to the mini-thermal power plant. The heat pipeline route is set in the Construction Urban Plan (GUP). The basic reasons for construction of a connecting heat pipeline are: connecting the facility to the central heating system, termination of several block boiler rooms and new residential construction.
A new heat pipeline route should be designed from the existing heat pipeline and the initial manhole to the connection to the mini-thermal power plant. The heat pipeline should be entirely in compliance with the route determined by the location permit and the prerequisites determined by special construction conditions. In addition, all existing municipal infrastructure should be entirely complied with.
According to the project task, the route consists of two parallel laid pipelines and the accompanying shafts in which the block elements and other elements used for maintenance and hot medium distribution technology will be situated. The pipelines are pre-insulated by polyurethane insulation in the exterior plastic pipeline, and are as such laid directly in the construction pit.
The mechanical engineering part of the project should contain the following calculations: the strength calculation, and pipeline elasticity calculation and the dilation calculation.

19th International Symposium and Exhibition of …, Jan 1, 2007

This paper provides an overview of a test performed on a blast valve for shelters according to th... more This paper provides an overview of a test performed on a blast valve for shelters according to the listed policies. In addition to the brief overview of the elements within the shelter ventilation system and description of the technical characteristics for the tested valve, the paper provides the course of the entire testing. This includes a description and chart of the measuring line, description of the test itself, and a tabular display of the test results. All of this is accompanied with pictures and relevant charts.

19th International Symposium and Exibition of Heating, …, Jan 1, 2007

The body and paint workshop provides for protection of the area by a stable fire extinguishing sy... more The body and paint workshop provides for protection of the area by a stable fire extinguishing system with FM-200 gas. The entire installation and its mechanical and electrical parts are
briefly described, as well as the alerting plan with the accompanying drawings and charts. In addition, the paper provides the system calculation and an overview of exploitation hazards, including the proposals for their removal. The paper also provides an overview of all the regulations and laws applied.

The 7th International Symposium Power and Process …, Jan 1, 2006

U radu je prikazano upravljanje elektromotornim pogonima u jednom sustavu klimatizacije u poslovn... more U radu je prikazano upravljanje elektromotornim pogonima u jednom sustavu klimatizacije u poslovnom prostoru. Na pocetku rada dan je opis same tehnologije sustava klimatizacije, sa zahtjevima koji se postavljaju na njega, te adekvatnim shemama. Nadalje su prikazane staticke karakteristike pumpi i ventilatora, uz osnovni opis njihovog rada i mogucnostima regulacije brzine vrtnje. Uz to dan je i osvrt na analizu i modeliranje rada asinhronih motora, sa prikazom jednadžbi stroja, jedinicnim vrijednostima, stacionarnim stanjem i bilancom energije. Prikazane su osnovne mogucnosti upravljanja elektromotornim pogonima sa asinhronim motorima. S obzirom na samu tehnologiju procesa i strukturu upravljanja, izbor je vec ovdje sveden na dva rješenja, te je dan osnovni princip skalarnog upravljanja, koji ce kasnije biti odabran kao idejno rješenje. Navedena rješenja su usporedena primjenom na konkretni slucaj sustava klimatizacije, sa nacrtima napajanja pumpi i ventilatora, kao i njihovim Q-H karakteristikama. Nakon toga slijedi odabir idejnog rješenja upravljanja s obzirom na energetske i upravljacko-regulacijske karakteristike. Uz to dan je i kratak osvrt na mogucnost uštede energije primjenom frekventnog pretvaraca u odnosu na regulaciju prigušivanjem.

18th International Symposium and Exhibition of …, Jan 1, 2005

U radu je analizirana primjena jednog algoritma upravljanja u svrhu poboljšanja sustava upravljan... more U radu je analizirana primjena jednog algoritma upravljanja u svrhu poboljšanja sustava upravljanja u kotlovnici (njenog ogrijevnog i rashladnog dijela). Obuhvaćene su: opis sustava (kotlovnice), karakteristike prediktivnog algoritma upravljanja, princip rada predikcijskih regulatora, osobittosti poopćenog predikcijskog regulatora (GPC), te realizacija samog sustava upravljanja, u ogrijevnom, te u rashladnom dijelu kotlovnice. Tu su prikazani njihovi matematički modeli, parametri kriterijske funkcije, formiranje referentne trajektorije, predikcija izlazne veličine procesa i minimizacija kriterijske funkcije.