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Analysis of Delays and Extension of Execution Duration of a Road Project

Abstract

The implementation of road infrastructure projects often results in delays due to objective causes, with repercussions on the final execution deadline and with value implications. The use of critical path method for planning and the executin windows, will result in better time process management and optimization delays.

Open access
Analysis of information security threats for developing DLP-systems

Abstract

The motivation of investigation is explained by the problem of keeping organisations’ information and private ones secure. One reason for this is insufficiency of information protection systems, and another – vulnerability in such kind of systems. The article is devoted to defining and analyzing the types and sources of information security threats for an automated system. It can be useful for developing the model method, having the purpose of detecting and further preventing of hazards. The safeness of Data Leak Prevention (DLP) system itself is also under investigation. The analysis was carried out by an expert method with system analysis. A DLP system was considered, on the one hand, as a way of information protection to prevent information leakage, and on the other hand, as an object of protection which is vulnerable to threats of information security. The presented threat model includes the sources of threats, divided into three large groups: anthropogenic, technogenic and spontaneous; and types of threats: intentional and unintentional.

Open access
The analysis of machine operation and equipment loss in ironworks and steelworks

Abstract

The article presents a case study of the identification and analysis of operating and equipment losses in a steel plant. Losses may be visible in costs resulting from premature wear of machine and equipment components, removal of emergency failures related to quality losses, including loss of reputation of a reliable supplier, as well as losses related to production, especially in the case of continuous production. The analysis of losses was based on the cost criterion, including losses resulting from the loss of a potential client. The real data from the 2016 were used in the case study. In order to ensure proper operation at the finishing department, standard solutions have been developed. The analysis of losses was based on the Pareto principle and the analysis of TPM coefficients.

Open access
A brief overview and metallography for commonly used materials in aero jet engine construction

Abstract

Aluminium, titanium, and nickel base alloys are mostly and widely used for aircraft jet engine construction. A proper evaluation of its microstructure is important from working safety point of view. To receive a well prepared sample of microstructure, some important steps have to be undertaken. Except for proper grinding and polishing of a sample, structure developing is a significant step, too. In order to develop microstructure various chemical reagents were used to achieve the best results for microstructure evaluation. The chemical reagents were used according to the previous knowledge and some new ones were also tested. Aluminium AK4-1č, titanium VT – 8, and nickel VŽL – 14 and ŽS6 – U alloys were used as an experimental materials. Alloy AK4-1č is used for fan blade production with working temperatures up to 300°C. It is a forged piece of metal machined down into final shape by five-axe milling machine. Alloy VT – 8 is used for high pressure compressor rotor blade production with working temperatures up to 500°C. Blades are forged as well and finally grinded. Finally nickel base alloys VŽL – 14 and ŽS6 – U are used for turbine blade production with working temperatures up 950°C. Blades for turbine are casted into mould with reducible models.

Open access
Comparison of low and high frequency fatigue tests

Abstract

The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100; high frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both fatigue tests were realised at sinusoidal cyclic push-pull loading (stress ratio R = −1) at ambient temperature (T = 20 ± 5 °C).

Open access
Difficulties in work safety management in a company producing steel flat bars

Abstract

According to research, metal processing industry has the highest risk of accidents at work, due to the necessity for personal protective equipment use and strict execution of safety rules and procedures. The paper presents the individual characteristics of health and safety management in the company producing steel flat bars. Special attention has been paid to the safety aspect of the use of automated logistical equipment (gantries, automatics) that increase the risk of work-related accidents. The results of research on the difficulties resulting from the specifics of production (metallurgical industry) has been presented.

Open access
Improving production of low pressure hoses

Abstract

The paper presents the results of research carried out in one of the domestic companies producing rubber and plastics products for the automotive industry. The results of the evaluation of the quality control function during production of the low pressure hoses and the characteristics of the main machine taking part in this production process are presented. An analysis of the results of the evaluation of factors influencing the quality of production is presented and guidelines for improving this production process are presented. One of the proposed solutions for improvement is the modernization of the machine park and introduction of production nests.

Open access
Influence of high temperatures on technical state of streets and roads structures with asphalt surfacing

Abstract

In this paper will be presented the influence of high temperatures on asphalt street pavement in terms of the influence of temperature on permanent deformations and thus the technical condition of the streets, comparable to the effects induced on extra-urban roads.

Environmental factors are one of the mayn factors being assaulted in operation and road structures are very important in terms of the influence they can have on the state road transport technical infrastructure.

Will be presented differences between urban road structures (streets) and extra-urban (road) both in terms of construction, the demands of traffic and environmental conditions to which they are subject.

Road structures extra-urban and urban areas are required differently in terms of the environmental conditions of the location ambient different thereof, that is, when the streets they are inside localities and the built environment significantly affect road infrastructure, unlike in the case of roads where they are located just outside the settlements, reducing the effect of air currents accumulation pavement surface temperature.

To demonstrate the influence of high temperatures on the pavement were conducted laboratory tests on asphalt mixtures in order to demonstrate the occurrence of reduction of physical characteristics, with adverse implications on the performance of applications similar to traffic.

Open access
Mathematical Models for Nonlinear Soil Behavior

Abstract

Actually, the seismic movement has an irregular cyclic character.This can be equivalent to a determined number of uniform cyclical stresses equivalent in terms of effect.

Modeling the behavior of the soil to cyclical stress, is usually done, by establishing a relationship for primary loading like τ = f (γ) and after drawing the diagram “effortless strain curve”, in which τ is the stress, and γ is shear deformation. For modeling nonlinear behavior of the soil, we used like nonlinear models. The best known are the hyperbolic model and the Ramberg-Osgood model.

Open access
Microstructural features evaluation of age-hardened A 226 cast alloy by image analysis

Abstract

Age-hardening provides one of the most widely used mechanisms for the strengthening of aluminum alloys. The age-hardening involves three steps: solution treatment, quenching and aging. The temperature of solution treatment and aging is very important in order to reach desired properties of castings. The optimum temperature of solution treatment and aging led to formation microstructural features in form which does not lead to decreasing properties, but increasing ones. The major micro-structural features in A 226 cast alloys which are responsible for increasing properties are: eutectic Si particles, Cu-rich phases, Fe-rich phases and porosity. The increase of properties depends on morphology, size and volume of microstructural features. In order to assess age-hardening influence on microstructural features in A226 cast alloys were used as possibilities of evaluation by means of image analysis. Quantitative analysis decelerate changes in microstructure includes the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe-rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu) further increase in the hardness and tensile strength in the alloy. Changes of mechanical properties were measured in line with STN EN ISO.

Open access