On fundamental principles of the optimal number and location of loading bays in urban areas

The paper is dealing with the problem of finding the optimal number and location of Loading Bays (LBs) for efficient urban last mile deliveries. To solve the problem a multi-parametric model of the idealized urban area is introduced and applied to various instances of a rectangular urban grid structured zones. Multi-parametric approach is used to assess statistically the most relevant number and location of LBs. Computational and graphical results of the idealized model exhibit geometric patterns showing that the optimal Number of LBs (#LB) naturally tends to perfect squares. Moreover, even in case of generalized instances, at a selected number of LBs their distribution is not random but follows specific laws. The optimality is closely related to the prefixed (maximal) walking distance dmax, from the LB to the customer. Based on various simulations the existence and robustness of a descending convex dependence dmax = (#LB) is proven. The results might serve as a decision-making tool to determine the optimal number and location of LBs for any real-life city centre

Stabilnost konstrukcij - zapiski predavanj

Zapiski predavanj zajemajo vsebino predmeta Stabilnost konstrukcij, ki se izvaja v 1. letniku drugostopenjskega magistrskega študijskega programa Gradbeništvo, smer Gradbene konstrukcije in operativa ter Gradbena infrastruktura, na Fakulteti za gradbeništvo, prometno inženirstvo in arhitekturo Univerze v Mariboru. Kot pomoč pri študiju ga lahko uporabijo tudi študenti drugih študijskih smeri, ki se srečujejo s problematiko stabilnosti konstrukcij in/ali fizikalnih sistemov. Zapiski predavanj so razdeljeni v več sklopov in sicer: (1) splošni uvod – motivacija in osnovni pojmi stabilnosti na splošno ter pri gradbenih konstrukcijah(2) inženirski koncepti stabilnosti(3) matematični kriteriji stabilnosti (za splošne sisteme po Lyapunovu in za konservativne sisteme z energijskim pristopom)(4) pristopi k reševanju stabilitenih problemov pri SDOF sistemih(5) analiza karakterističnih tipov izgube stabilnosti pri SDOF sistemih(6) določitev osnovnih področij stabilnosti za karakteristične tipe izgube stabilnosti pri SDOF sistemih(7) vpliv plastifikacije na stabilnost pri SDOF sistemih(8) stabilitetna analiza enostavnih MDOF sistemov(9) stabilnost enostavnih konstrukcij iz linijskih elementov konstatnega prereza – zvezni sistemi(10) deformacijska metoda pri analizi stabilnosti konstrukcij(11) poenostavljena metoda določevanja kritične obtežbe ravninskih okvirov in (12) določanje karakterističnih površin za okvirne konstrukcije

Prediction of soil factors by a non-parametric approach

The problem addressed in this paper is the estimation of the (de)amplification of ground motion at soil sites (compared to rock sites) as a function of the intensity of ground motion. A non-parametric empirical approach, called the CAE (Conditional Average Estimator) method has been used. Soil factors (SFs) for peak ground acceleration and spectral accelerations were predicted by using combined PEER and European database of recorded ground motions. Comparisons were made with SFs used in codes (Eurocode 8 and ASCE 7-10), with SFs proposed by Huang-Whittaker-Luco, with SFs obtained from four NGA GMPEs, and the European Akkar-Bommer model. The study reveals that: (1) SFs depend strongly on the ground motion intensity. They depend also on the magnitude of the earthquake. (2) Existing models yield very different results for SFs. (3) SFs predicted in this study are, for higher intensities of ground motion, generally smaller than the existing ones

Flexible Assignment of Loading Bays for Efficient Vehicle Routing in Urban Last Mile Delivery

Urban freight deliveries are often subject to many access restrictions which creates the need to establish a system of loading bays and to split the last mile delivery into driving and walking parts. A new model based on hard and soft clustering approach is developed to solve the loading bay assignment problem for efficient vehicle routing and walking in last mile delivery. The flexibility of the model is provided by the soft clustering approach based on different membership degrees of customers to loading bays. Especially for instances with large numbers of loading bays, soft clustering seems to give better results, it leads to higher flexibility of city logistics systems, minimal driving distances, and adequately short walking paths, which contribute to the goal of reaching sustainable urban freight deliveries

Contour maps for simultaneous increase in yield strength and elongation of hot extruded aluminum alloy 6082

In this paper, the Conditional Average Estimator artificial neural network (CAE ANN) was used to analyze the influence of chemical composition in conjunction with selected process parameters on the yield strength and elongation of an extruded 6082 aluminum alloy (AA6082) profile. Analysis focused on the optimization of mechanical properties as a function of casting temperature, casting speed, addition rate of alloy wire, ram speed, extrusion ratio, and number of extrusion strands on one side, and different contents of chemical elements, i.e., Si, Mn, Mg, and Fe, on the other side. The obtained results revealed very complex non-linear relationships between all of these parameters. Using the proposed approach, it was possible to identify the combinations of chemical composition and process parameters as well as their values for a simultaneous increase of yield strength and elongation of extruded profiles. These results are a contribution of the presented study in comparison with published research results of similar studies in this field. Application of the proposed approach, either in the research and/or in industrial aluminum production, suggests a further increase in the relevant mechanical properties

Influence of cooling mode in relation to casting and extrusion parameters on mechanical properties of AA6082

In this study, conditional average estimator neural networks (CAE NNs) were used for an analysis of the common influences of the cooling mode in relation to the ram speed, extrusion ratio, casting speed and casting temperature on the yield strength and the elongation of an extruded profile made from aluminium alloy (AA)6082. The obtained results from the analysis revealed very complex relationships between these parameters. In order to maximise the values for the yield strength and the elongation, the values for the ram speed, extrusion ratio, casting speed and casting temperature should be optimised in relation to the mode of cooling

A New Beam Finite Element for Static Bending Analysis of Slender Transversely Cracked Beams on Two-Parametric Soils

This paper derives an original finite element for the static bending analysis of a transversely cracked uniform beam resting on a two-parametric elastic foundation. In the simplified computational model based on the Euler–Bernoulli theory of small displacements, the crack is represented by a linear rotational spring connecting two elastic members. The derivations of approximate transverse displacement functions, stiffness matrix coefficients, and the load vector for a linearly distributed load along the entire beam element are based on novel cubic polynomial interpolation functions, including the second soil parameter. Moreover, all derived expressions are obtained in closed forms, which allow easy implementation in existing finite element software. Two numerical examples are presented in order to substantiate the discussed approach. They cover both possible analytical solution forms that may occur (depending on the problem parameters) from the same governing differential equation of the considered problem. Therefore, several response parameters are studied for each example (with additional emphasis on their convergence) and compared with the corresponding analytical solution, thus proving the quality of the obtained finite element