The paper is focused on the forthcoming IEEE 802.11ax standard and its influence on Wi-Fi networks performance. The most important features dedicated to improve transmission effectiveness are presented. Furthermore, the simulation results of a new transmission modes are described. The comparison with the legacy IEEE 802.11n/ac standards shows that even partial implementation of a new standard should bring significant throughput improvements.
The performance-based analysis of the large-space steel sports hall is presented. Load-bearing structure of the hall consists of spatial long-span truss girders that are made of modern square hollow sections. Both fire development analysis and mechanical response analysis are discussed in detail. Fire Dynamics Simulator and Safir programs are used. Main focus is put on the factors that could affect the final fire resistance of the structure. Uniform and non-uniform heating, different boundary conditions and local imperfections are taken into account. Structures with and without fireproof insulation are considered. Values of the critical temperature, failure modes and fire resistance estimated for various cases are presented. Computer simulations were carried out both for fire growth and decay phase. As a result it is clearly shown that some reductions of the required fireproof insulation are possible. Moreover, the structure without complete traditional fireproof insulation is able to survive not only the direct fire exposure but also the cooling phase.
Predicting the aging process of residential buildings carried out using traditional technologies is necessary when planning refurbishment works in these buildings. The article presents a picture of the changes in the technical condition of a not refurbished building constructed in traditional technology, in the form of a function describing the aging process according to the PRRD (Prediction of Reliability according to Rayleigh Distribution) model developed by the author. The results of analyses of the relationships between the function of the intensity of damage and the function of unreliability, as well as the function of changes in the performance characteristics of a building which had not undergone refurbishment during the entire course of its use are presented. Three levels of damage intensity during subsequent years of using the building were determined: safe, critical and unacceptable intensity.
This study analyzed the role of PERFORM 3D in the preliminary evaluation of seismic performance of engineering structures. Firstly, PERFORM 3D was briefly introduced, and its material constitutive model and basic model were analyzed. Then, taking a high-rise building project in Yulin, Shaanxi, China, as an example, PERFORM 3D was used to evaluate its seismic performance. After establishing the engineering model, five seismic waves were selected for simulation. The results showed that the maximum values of X-axis inter-story displacement angle and Y-axis displacement angle were 1/500 and 1/360 respectively, which were far less than the standard limit; the overall energy dissipation was good, the damping was small, the overall deformation was good, and the seismic performance was also good. In conclusion, PERFORM 3D has a good performance in the preliminary evaluation of seismic performance of engineering, and it is worth further promotion and application.
From all the detonation parameters of explosives, “strength” – the capability to perform work is the most important for the user. The detonation of explosives in the blast hole is a quick and complicated process: first there is a detonation pressure causing the crushing of the rock in the vicinity of the explosive, then the pressure of the detonation products causes the cracking of the rock. The article presents the methods of determining the capability to perform work by explosives for civil use (dynamite and ANFO) used in the accredited Laboratory of Explosives and Electric Detonators Testing of the Experimental Mine “Barbara” of the Central Mining Institute – the lead block (Trauzl) method and the ballistic pendulum method. The aim of the research was to determine the relationship between the values of the capability to perform the work received in a ballistic pendulum method and a lead block method. As a result of the performed tests and the analysis of the results, the α-Pb coefficient was determined, which can be used to convert the value of the capability to perform work on the ballistic pendulum to the corresponding value of the capability to perform work in the lead block. At present, the Central Mining Institute is the only Notified Body of the European Union in the scope of Directive 2014/28 /EU, which has a station for smelting lead blocks and equipment and for determining the capability to perform work by explosives in lead blocks – this method was abandoned in other research units for testing with a ballistic pendulum and/or underwater test.
Assumptions of the major political and legal documents of the European Union, dedicated to energy efficiency and energy performance of buildings provide the Member States with relevant instruments supporting improvement of the ambient air qualityby dissemination of measures reducing energy demand and promotion of renewable energysources. Mainstreaming EU legislation into national regulations constitutes initial stage of the long term process of supporting implementation of energy efficiency measures. Experience in the improvement of energy performance of the residential buildings revealslimited efficiency of the measures implemented up to date, which results in significantair pollution of Polish cities. The national Action Plans had adopted a limited scope of recommendations included in the EU directives, hence the process meets significant challenges.The article describes adaptation of the relevant EU directives as well as the National Urban Policy in terms of the potential to effectively address faced challenges.
The article presents research on the relationship between mining and used resources on the example of Gliśno gravel pit. As regards to resources, the following issues were analyzed: employees’ working time, time of running machines, fuel consumption and electricity consumption. The aim of the publication is to examine the dependencies that exist between the analyzed variables. KPI’s (Key Performance Indicators) were calculated for individual resources. The analysis presented in the publication contains data from 2008-2014.
Although the usefulness of alternative assessment in second language (L2) classrooms has been extensively recognized by scholars, the use of the various types of alternative assessment in English as a Foreign Language (EFL) contexts has not received adequate attention by L2 practitioners. To contribute to this line of research, the present research sought to examine the impact of a portfolio-based writing instruction on writing performance and writing anxiety of EFL students. To this end, a number of 41 EFL learners were recruited as the participants of this study. They were then randomly divided to an experimental group (N=21) and a control group (N=20). The participants in the experimental group received portfolio-based writing instruction, whereas the control group received the regular writing instruction with no archiving of students’ drafts in portfolios. Timed-writing tasks and the Second Language Writing Anxiety Inventory (SLWAI) were employed to collect the data. The results obtained from ANCOVA analysis revealed that the portfolio-based writing instruction aided the participants in improving their writing performance more than the control group. Moreover, it was found that the use of portfolios significantly reduced the L2 writing anxiety of the participants while the traditional writing instruction did not have any significant impact on L2 writing anxiety of the control group. The pedagogical implications for portfolio-based writing instruction are discussed finally.
Infiltration process plays important role in water balance concept particularly in runoff analysis, groundwater re-charged, and water conservation. Hence, increasing knowledge concerning infiltration process becomes essential for water manager to gain an effective solution to water resources problems. This study employed multiple linear regression for esti-mating infiltration rate where the soil properties used as the predictor variable and measured infiltration rate as the response variable. Field measurement was conducted at sixteen points to obtain infiltration rate using double ring infiltrometer and soil properties namely soil porosity, silt, clay, sand content, degree of saturation, and water content. The result showed that measured infiltration rate had an average initial infiltration rate (f0) of 6.92 mm∙min–1 and final infiltration rate (fc) of 1.49 mm∙min–1. Soil porosity and sand content showed a positive correlation with infiltration rate by 0.842, 0.639, respectively, while silt, clay, water content, and degree of saturation exhibited a negative correlation by –0.631, –0.743, –0.66 and –0.49, respectively. Three types of regression equations were established based on type of soil properties used as predictor varia-bles. The model performance analysis was conducted for each equation and the result shows that the equation with five predictor variables fMLR_3 = – 62.014 + 1.142 soil porosity – 0.205 clay, – 0.063 sand – 0.301, silt + 0.07 soil water content with R2 (0.87) and Nash–Sutcliffe (0.998) gave the best result for estimating infiltration rate. The study found that soil po-rosity contributes mostly to the regression equation that indicates great influence in controlling soil infiltration behavior.