Application of Set Covering Location Problem for Organizing the Public Postal Network

Most countries of the European Union ensure certain obligations (criteria) which universal service providers must meet to ensure the realization of the universal service. These criteria vary from country to country, giving their own choice of an optimal model for the density of the postal network. Such postal network of the operator providing universal postal service must be organized so that post offices are accessible at the optimal distance from the user. This paper presents two different approaches. The first one is based on the population criteria determined in the previous study. The second one is new, a general method created to determine the minimum number of postal unit applications of Set Covering Location Problem. The authors apply both methods on real data collected from the Serbian municipalities and finally, compare the obtained results.</p

Application of Set Covering Location Problem for Organizing the Public Postal Network

Most countries of the European Union ensure certain obligations (criteria) which universal service providers must meet to ensure the realization of the universal service. These criteria vary from country to country, giving their own choice of an optimal model for the density of the postal network. Such postal network of the operator providing universal postal service must be organized so that post offices are accessible at the optimal distance from the user. This paper presents two different approaches. The first one is based on the population criteria determined in the previous study. The second one is new, a general method created to determine the minimum number of postal unit applications of Set Covering Location Problem. The authors apply both methods on real data collected from the Serbian municipalities and finally, compare the obtained results.</p

Neuro-fuzzy inference systems approach to decision support system for economic order quantity

Supply chain management (SCM) has a dynamic structure involving the constant flow of information, product, and funds among different participants. SCM is a complex process and most often characterized by uncertainty. Many values are stochastic and cannot be precisely determined and described by classical mathematical methods. Therefore, in solving real and complex problems individual methods of artificial intelligence are increasingly used, or their combination in the form of hybrid methods. This paper has proposed the decision support system for determining economic order quantity and order implementation based on Adaptive neuro-fuzzy inference systems - ANFIS. A combination of two concepts of artificial intelligence in the form of hybrid neuro-fuzzy method has been applied into the decision support system in order to exploit the individual advantages of both methods. This method can deal with complexity and uncertainty in SCM better than classical methods because they it stems from experts’ opinions. The proposed decision support system showed good results for determining the amount of economic order and it is presented as a successful tool for planning in SCM. Sensitivity analysis has been applied, which indicates that the decision sup- port system gives valid results. The proposed system is flexible and can be applied to various types of goods in SC

Urban Planning Impact on Mobility and Residential Satisfaction of Older People in Novi Sad

Social, political and economic changes have generated processes of revitalization of the built environment in post-socialist countries since the beginning of the 1990s; these changes are related to the physical structure of the city, its facilities and its functions, as well as the city landscape. Urban planning affects people’s quality of and way of life, as well as residential satisfaction with the built environment, especially that of older people, who make up a significant part of sustainable communities. This paper examines the residential satisfaction of older adults in terms of mobility—that is, their ability to move using facilities offered by public transportation and public places—in two neighborhoods of Novi Sad which have undergone the most extensive urban regeneration. This approach is different from the existing urban studies dealing with residential satisfaction, which makes it a contribution to the literature. Unlike previous studies—which have explored residential satisfaction at the level of accessibility to local facilities, safety in the urban environment and support from the environment—this paper also investigates the impact of movement in public space on the residential satisfaction of older people. The results show that the residential satisfaction of older people is low with regard to public transport, the arrangement of public spaces and traffic infrastructure

Optimum Fluid Content in Pavement Cold In-Place Recycling Containing Waste Materials

The planning of road infrastructure undergoes major changes, especially in terms of sustainable development. Recycling of pavement structures involves the reuse of materials from existing pavement structures due to its timesaving and environmental benefits, as well as cost reduction. According to the recycling temperature, recycling can be hot and cold. This paper deals with cold in-place recycling and the determination of the optimum fluid content for by-product materials in mixtures compared with one containing natural zeolite. The content of bitumen emulsion and cement&mdash;which are the most used materials so far in cold recycling along with foam bitumen&mdash;was replaced with fly ash, slag or natural zeolite, and bakelite, respectively, while recycled asphalt pavement from Serbia (&#381;abalj) was used. Six different mixtures were made. The mixture with the addition of fly ash had the highest optimum fluid content (7.6%) compared with all test mixtures. Mixtures with slag, natural zeolite, and bakelite were in the range of a mixture containing 2% cement. Furthermore, the mixture with 3% cement had the lowest optimum fluid content (5.7%) in comparison to all the mixtures that were tested

Principles of the design of urban space that support rail systems from the aspect of urban elements and elements of the relief ; Načela za oblikovanje urbanih prostorov, ki podpirajo tirnične sisteme, z vidika urbanih elementov in elementov reliefa

Pri multimodalnem pristopu k uravnoteženi zastopanosti oblik javnega in zasebnega prevoza tirnični sistemi prispevajo k rešitvi prometnih težav v modernih mestih. Njihovo uvajanje v urbane enote omogoča urbano transformacijo, ki lahko z racionalno rabo energije, zmanjšanjem hrupa in onesnaženosti zraka, zmanjšanjem prometne gneče, socialno integracijo na javnih mestnih prostorih, funkcionalnostjo urbanih enot in privlačnostjo urbane oblike prispeva k mestu, ki je trajnostno in prijazno za bivanje. Prostorske elemente tirničnih sistemov je mogoče spraviti v ustrezno razmerje z urbanimi elementi in elementi reliefa. Z oblikovanjem odnosov med temi elementi na ravni javnih mestnih prostorov, in sicer na podlagi arhitekturnih načel, je mogoče oblikovati funkcionalne urbane enote posebne oblike in urbane zasnove. Cilj dela je ugotoviti, kako je mogoče spraviti navedene elemente v prostorski odnos, da bi javni mestni prostori, ki vsebujejo tirnične sisteme, prispevali k funkcionalnosti in privlačnosti za bivanje prijazne in trajnostne urbane oblike. Cilj je tudi ugotoviti, kako konfiguracijo terena, z vsemi njenimi elementi, spraviti v proces digitalnega projektiranja urbanih prostorov, ki vsebujejo tirnične sisteme ; In the multimodal approach to a balanced representation of public and private transportation, rail systems contribute to the solution to the problem of traffic in modern cities. The introduction of these systems in urban units enables the creation of urban transformations that can contribute to livable and sustainable cities, through the rational use of energy, reduction of noise and air pollution, reduction of traffic jams, social interactions in public spaces, functionality of urban totalities and the attractiveness of the urban form. Spatial components of rail systems can be related with the urban elements and the elements of landscape. Through relating these elements at the level of public spaces, and based on architectural principles, it is possible to create functional urban totalities of specific form and urban design. The objective of this study is to determine the way in which these elements can be spatially related in order to enable the contribution of public areas containing rail systems to the attractiveness of livable and sustainable urban form. The objective is also to establish criteria based on which the configuration of terrain with all its elements will be introduced into the process of designing urban spaces that include rail systems

A Novel Multiphase Model for Traffic Safety Evaluation: A Case Study of South Africa

Identification of key indicators that cause safety challenges and vulnerable roads is crucial for improving traffic safety. This paper, therefore, entails to the development of a novel multiphase multicriteria decision-making (MCDM) model to evaluate the vulnerability of urban roads for traffic safety. This was conducted by using data from 17 important roads of a South African city and combining several methods such as CRiteria Importance through Intercriteria Correlation (CRITIC), data envelopment analysis (DEA), and measurement of alternatives and ranking according to compromise solution (MARCOS). Taking the elements of the DEA method, two new approaches for calculating the weights of criteria, the DEA-1 and DEA-2 models, were formed and integrated with the CRITIC method to obtain the final values of criteria weights. The MARCOS method was applied to evaluate 17 alternatives, for each direction separately. The aim of developing such a model is to use the advantages of obtaining objectivity of criteria weights through linear programming and correlation of values of the collected data. Also, the MARCOS method, as one of the newer and applicable methods, provides additional significance. Extensive sensitivity analyses were conducted to validate the model. The findings suggest that there are a certain number of roads that have a high level of safety for both directions, as well as a group of risky roads, which need traffic improvement measures. Thus, the results indicate that the model is sensitive to various approaches and can prioritize vulnerable roads comprehensively based on which safety measures can be taken

Management in the delivery of hazardous material packages using courier services

The paper studies the transportation of hazardous materials with a focus on the delivery of hazardous material packages using courier services. The managerial approach to solving the problem of package shipment is the basic characteristics and the essence of modern management in courier services, without which it is impossible to imagine a more efficient operation, work and development. Transportation of hazardous materials has to be organized according to certain regulations, which are defined for each means of transportation, in order to minimize the risk of accidents. Hazardous materials shipments using courier services with transport reliefs are possible with 'limited quantities' and 'exclusion under transport category'

Optimum Fluid Content in Pavement Cold In-Place Recycling Containing Waste Materials

The planning of road infrastructure undergoes major changes, especially in terms of sustainable development. Recycling of pavement structures involves the reuse of materials from existing pavement structures due to its timesaving and environmental benefits, as well as cost reduction. According to the recycling temperature, recycling can be hot and cold. This paper deals with cold in-place recycling and the determination of the optimum fluid content for by-product materials in mixtures compared with one containing natural zeolite. The content of bitumen emulsion and cement—which are the most used materials so far in cold recycling along with foam bitumen—was replaced with fly ash, slag or natural zeolite, and bakelite, respectively, while recycled asphalt pavement from Serbia (Žabalj) was used. Six different mixtures were made. The mixture with the addition of fly ash had the highest optimum fluid content (7.6%) compared with all test mixtures. Mixtures with slag, natural zeolite, and bakelite were in the range of a mixture containing 2% cement. Furthermore, the mixture with 3% cement had the lowest optimum fluid content (5.7%) in comparison to all the mixtures that were tested

Model for Risk Calculation and Reliability Comparison of Level Crossings

There is not a single country in the world that is so rich that it can remove all level crossings or provide their denivelation in order to absolutely avoid the possibility of accidents at the intersections of railways and road traffic. In the Republic of Serbia alone, the largest number of accidents occur at passive crossings, which make up three-quarters of the total number of crossings. Therefore, it is necessary to constantly find solutions to the problem of priorities when choosing level crossings where it is necessary to raise the level of security, primarily by analyzing the risk and reliability at all level crossings. This paper presents a model that enables this. The calculation of the maximal risk of a level crossing is achieved under the conditions of generating the maximum entropy in the virtual operating mode. The basis of the model is a heterogeneous queuing system. Maximum entropy is based on the mandatory application of an exponential distribution. The system is Markovian and is solved by a standard analytical concept. The basic input parameters for the calculation of the maximal risk are the geometric characteristics of the level crossing and the intensities and structure of the flows of road and railway vehicles. The real risk is based on statistical records of accidents and flow intensities. The exact reliability of the level crossing is calculated from the ratio of real and maximal risk, which enables their further comparison in order to raise the level of safety, and that is the basic idea of this paper