Road safety has an extremely important role in existing transportation systems. Drivers on the road are influenced by various factors (light and temperature conditions, visual smog, environment surrounding, etc.) and driver´s distraction represents the most common cause of road traffic accidents. According our previous researches, we found that visual smog has a negative influence on drivers on the road. However, the task of placing the traffic signs on the roads is to increase road safety, thus positively influencing the driver while driving. The main objective of this article is to measure the visibility of traffic signs on selected roads in specific light conditions (in night). Secondary objective is to measure visibility of roadside advertisement (billboards) near roads that are influencing driver´s distractions in negative way. The mobile ETG technology (eye tracking glasses) has been used as a method for measuring the gaze of the driver's eyes on traffic signs in night conditions. We compared the results from our previous research (daylight conditions) with the obtained results from the current research. On the basis of the comparison of both measurements we can find out differences (positive and negative) in influence of traffic signs and road side advertisements on drivers in various light conditions.
This paper aims to present the effect of specific operational factors (temperature and humidity) on the selected mechanical properties of a conveyor belt. The tests were conducted in a climatic chamber, simulating the effect of both minus and plus temperatures −30 °C to 80 °C (243 K to 353 K) at specific humidity, and in a thermal shock chamber where a varying number of ageing cycles was applied for a specific range of thermal shocks. Six different tests in the climatic chamber and four different tests in a thermal shock chamber were conducted. The results of the climatic chamber tests demonstrate that many strength parameters have undesired values at a temperature of 10 °C (283 K) and 80 °C (353 K) at a relative humidity of 80%. Interestingly, the results revealed that tensile strength, tensile modulus and yield strength are higher at below 0 °C temperature than at above 0 °C temperature. For example, comparing the temperature −30 °C (243 K) and +30 °C (303 K) obtained a difference of tensile modulus of nearly 10%, and comparing the temperature −30 °C (243 K) and +10 °C (283 K) the differences were 22%.
The optimizing process of the postal transportation network can be based on several variables and on different infrastructures. The most commonly used variables for optimization are time and distance. This article is focused on the comparison of the results of the optimization process based on the time and distance variables in the conditions of the Slovak national postal operator.The different types of the underlying infrastructures (roads or railways) could be used for optimization based on the territory conditions. For the optimization, there has been used the p-median method, that describes the problem of locating P "facilities" relative to a set of "customers" in such a way that the sum of the shortest demand weighted distance between "customers" and "facilities" is minimized.In the conclusion, the article authors will formulate the rule for selection of the best optimization variables for the postal transportation network optimization.
The article deals with the optimizing the postal transportation network with two different optimizing methods. The research adopted in this article uses allocation models within graph theory to obtain results for addressed optimization problem. The article presents and compares two types of these models: p-median and uncapacitated fixed charge facility location model. The aim of p-median model is to find the location of P facilities in network, serving all demands in a way ensuring the average transport cost to be minimal. Fixed charge location model approach the issue of facility location based on minimizing the overall costs of implementation of selected variants. The latter this two models are subsequently applied on the postal network to determine the optimal location of postal facilities. These two models are adopted in the condition of large country with area above 300 000 km2. The Italy was chosen as a typical country that fits this condition. The underlying infrastructure of Italy is represented by simplified model of a postal network, abstracted by a graph G = (V, E, c, w).
The results can serve as a basis for modification of the used models for the simulation of networks in the postal sector and as a key that compares the opportunities and results of application of these two models in the conditions large countries.
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