Modified PROMETHEE Approach for Solving Multi-Criteria Location Problems with Complex Criteria Functions

The specific problem that occurs in multi-criteria decision-making (MCDM) processes is ranking a number of alternatives using complex criteria functions (the hierarchical structure of criteria) whose values must consider the impacts of all-important characteristics and parameters of alternatives. The problem becomes more complex by increasing the number of levels of sub-criteria functions (degree of decomposition). This paper proposes an extended procedure based on the mean values conversion of the net outranking flow of sub-criterion functions obtained by modified PROMETHEE methods. The actual value of criterion functions is used only at the last level, and transformed values of the net outranking flow for generating a final rank of alternatives are introduced at other levels. This procedure provides a more objective comparison of the impact of various individual criteria to rank the alternatives and easier making of unique solution, where the impact of decision-maker (DM) experience and subjective estimation is minimised in the selection. Applicability and practicability of the presented procedure for solving the selection problem of a logistics warehouse location are demonstrated in the analysis of a case study example

Modeling of Arterial Stiffness using Variations of Pulse Transit Time

In this paper, a finite element (FE) modeling is used to model effects of the arterial stiffness on the different signal patterns of the pulse transit time (PTT). Several different breathing patterns of the three subjects are measured with PTT signal and corresponding finite element model of the straight elastic artery is applied. The computational fluid-structure model provides arterial elastic behavior and fitting procedure was applied in order to estimate Young's module of stiffness of the artery. It was found that approximately same elastic Young's module can be fitted for specific subject with different breathing patterns which validate this methodology for possible noninvasive determination of the arterial stiffness

Transient finite element modeling of functional electrical stimulation

Transcutaneous functional electrical stimulation is commonly used for strengthening muscle. However, transient effects during stimulation are not yet well explored. The effect of an amplitude change of the stimulation can be described by static model, but there is no differency for different pulse duration. The aim of this study is to present the finite element (FE) model of a transient electrical stimulation on the forearm. Discrete FE equations were derived by using a standard Galerkin procedure. Different tissue conductive and dielectric properties are fitted using least square method and trial and error analysis from experimental measurement. This study showed that FE modeling of electrical stimulation can give the spatial-temporal distribution of applied current in the forearm. Three different cases were modeled with the same geometry but with different input of the current pulse, in order to fit the tissue properties by using transient FE analysis. All three cases were compared with experimental measurements of intramuscular voltage on one volunteer

Primena metode konačnih razlika kod određivanja ugiba nosača kontinualno promenljivog poprečnog preseka

Amongst others, the deformation criterion is to be fulfilled in the process of steel structure design. Often, it can be more restrictive than the stress criterion. Although the stress state is within the permissible limit, excessive structure deformation can lead the additional load to emerge in the carrying structure and cause improper operation and shorter life of attached devices and equipment. For that reason, besides other requirements, the allowable deformation limits of the steel carrying structure are defined. The stress-strain analysis of the structure is usually conducted by utilization of finite element method (FEM) in the early phase of the design process. Alternatively, this paper shows the application procedure of the finite difference method (FDM) for the deflection determination on the simple elastically restrained cantilever beam with continuously varying box-like cross-section and linear change of section height. Dependence of the deflection on the design parameters is obtained through programming in MATLAB and the comparison is made with the results from the finite element model built in ANSYS. The results from both numerical approaches showed excellent compliance.Publishe

Komparativna analiza i optimizacija T i I poprečnih preseka dizalične kuke primenom dva algoritma inspirisana fizikom

This paper presents analysis and optimization of the geometric parameters of T and I cross-sections of crane hook, observed for the most critical location of its structure. The reduction of the cross-sectional area of crane hook was set as the goal in this study. The stresses at characteristic points of the most critical cross-section are taken as constraint functions, calculated according to Winkler-Bach theory, and some geometric conditions are set, too. Two metaheuristic algorithms based on the laws of physics, Charged System Search (CSS) algorithm and Thermal Exchange Optimization (TEO) algorithm, were selected for optimization methods, using by MATLAB software package. The goal of this research is to show that the proposed cross-sections give significant savings in comparison to standard crane hook, wherein the one standard capacity was observed. Both observed cross-sections were analyzed in two variants, and the comparison of their optimization results was performed to show which one achieves the best results. Also, the comparison of the applied optimization algorithms was performed.Publishe

Aksijalno-radijalni ležaj kao segment veze okretne platforme sa nosećom konstrukcijom

The paper presents the connection of rotating platforms in building and transport machines depending on the type of driving mechanism. A special attention is paid to axial-radial bearings having big diameters made by prominent manufacturers. There are some necessary conditions which have to be met by supporting frames because working capacity of the bearings depends on them. Also, the law of distribution of load of moment of external forces is proposed because it provides identification of maximum load as a starting basis for further research on determination of optimal laws of distribution of acting forces which are caused by the moment of forces.Publishe

Prilog analizi krutosti ramova utovarno-istovarnih kolica pretovarnih mosnih dizalica

The paper analyzes the dependence of the stiffness of the support frames of the cranes with loading-unloading trolley on the change of geometrical parameters of the frames. The calculation model of the frames with transverse stiffness was formed because it additionally stiffens the supporting surface of the frames for connection with the axial-radial bearing. The relations of characteristic geometrical sizes of longitudinal and transverse elements were established, at which the necessary stiffness of the frames of loading-unloading trolley was achieved. Also, the variables and constants of geometric size were introduced, as well as the constant values of appropriate coefficients, the variation of which provides the possibility to form the optimal structure of the frames of loading-unloading trolley.Publishe

Stabilnost i optimizacija stuba dizalične staze

This research has presented the built-up column analysis with batten, applied to crane runaway support, where stability is put in the foreground. Also, optimization of all essential geometrical parameters of the built-up column was performed for a given height of the crane column and changing the load capacity. The chord members were composed of as-welded I-sections instead of fabricated hot rolled sections witch are commonly used in these constructions. The mass of the built-up columns, which consists of the chord and Web members (battens) members, was taken as the goal function in this research. Additional stability and load capacity conditions were used as constraint functions, as well as specific design recommendations. The optimization procedure was performed in the Ms. EXCEL software package, using the GRG2 algorithm because certain benefits are essential in this optimization problem. In this way, the justification of applying the proposed model of calculation and optimization was shown because the necessary geometrical parameters can be reached very quickly when designing these types of structures, considering that there are a large number of variables and constraint functions. It is also shown how the mass of the column changes and the optimal geometric parameters when the compression force on the column of the runaway crane support increases.Publishe

ARTreat Project: Three-Dimensional Numerical Simulation of Plaque Formation and Development in the Arteries

Atherosclerosis is a progressive disease characterized by the accumulation of lipids and fibrous elements in arteries. It is characterized by dysfunction of endothelium and vasculitis, and accumulation of lipid, cholesterol, and cell elements inside blood vessel wall. In this study, a continuum-based approach for plaque formation and development in 3-D is presented. The blood flow is simulated by the 3-D Navier-Stokes equations, together with the continuity equation while low-density lipoprotein (LDL) transport in lumen of the vessel is coupled with Kedem-Katchalsky equations. The inflammatory process was solved using three additional reaction-diffusion partial differential equations. Transport of labeled LDL was fitted with our experiment on the rabbit animal model. Matching with histological data for LDL localization was achieved. Also, 3-D model of the straight artery with initial mild constriction of 30% plaque for formation and development is presented