In this paper a dual direct torque control (DDTC) strategy with second-order sliding mode control (SOSMC) controller of the doubly fed Induction motor (DFIM) is presented in order to overcome some drawback such as ripples in torque, flux and to improve dual direct torque control (DDTC) performance toward the electrical parameters variations. This control strategy used in the doubly fed induction machine supplied, coupled by two voltage source inverters in rotor and stator sides witches are linked to two switching tables in order to determined the rotor and stator flux vector control. This controller based on super-twisting algorithm (STA). Comparative results between a classical controller (PI) and the proposed controller can prove the very satisfactory performance and robustness of this new controller.

The article presents the results of studies of energy, environmental and fuel efficiency indicators of a passenger car with a gasoline injection system. The engine is equipped with a device additionally supplying liquefied petroleum gas (LPG) and it has an ignition timing variator (ITV). As a result of research, an improvement in the fuel efficiency of a car in thermal equivalent was found when the engine was running on LPG and a slight increase in energy performance was observed. Emissions of pollutants with exhaust gases change in different ways: emissions of carbon monoxide practically do not change, emissions of hydrocarbons and nitrogen oxides are growing, carbon dioxide emissions from LPG operation are reduced, socio-economic damage when the engine is running on LPG is also reduced.

The dewatering performance of geotubes is affected by the silt content of filling sand, which limits the construction speed of geotubes. In order to evaluate the effect of silt content of filling sand on the dewatering performance of geotubes, a series of hanging bag tests were carried-out by varying filling sand with five different silt content. In the tests, the variation of the water loss, soil loss and soil particles grading with time were studied. And the relationship between the silt content and the rate of water loss was analyzed. The research results show that the dewatering process could be divided into three stages, when the powder content is more than 20 %. Otherwise, the dewatering process only includes two stages. Three different bell-shaped function relationships exist between the percentage content of silt particles, median particle size and non-uniformity coefficient with the rate of water loss respectively. Furthermore, the different relationships were simplified into 3 different linear functions correspondingly. The research results could be used as a reference for geotubes engineering practice.

The intention of this study was to create a computational model in micro-scale that allows to imitate heat and mass transfer through three-dimensional textile layer with and without forced ventilation. The four ventilation rates were used 0, 0.2, 0.4 and 0.8 dm3min-1. Approximation of a unit cell geometry and heat transfer process were considered. The time-dependent and steady-state simulations are based on Navier-Stokes/Brinkman partial differential equations, and energy equation. A finite element modelling package Comsol Multiphysics was used for numerical simulations. The Laminar flow (.spf) and Heat transfer in fluids (.ht) modes were coupled with non-isothermal flow (.nitf) multi-physics. The post-processing analysis was done using Matlab software. The outcomes of simulation are temperature distributions, surface average temperature and relative humidity through the thickness of the representative volume. The results enable to create a macro-scale models for efficient simulation of heat exchange in textile packages.

Rock contains a large number of micro-pores, which are of different shapes and complex structures. The structure information of sandstones is extracted based on different porosities through X-ray CT (Computer Tomography) scanning, photo processing techniques and complex network method to explore the topological structure of sandstone seepage network. The results show that sandstone seepage network has scale-free property. The minute quantities of pores with more throat connections have vital functions of overall connectivity of sandstone seepage network, while sandstone seepage network has strong robustness with random error. This research can provide reference for across scales research of porous seepage and multi-disciplinary application of complex network theory.

In recent years, industrial applications have been based on the use of intrinsic material properties that improve designs, processes, qualities and product controls. To get to those intrinsic parameters, various appropriate techniques are required. In this paper, a new technique has been developed and presented. It essentially puts the emphasis on the dielectric relative permittivity extraction from the principle of a movable short-circuit through the coaxial transmission-line cell. This technique is aimed at drastically reducing the discontinuity impacts at the interface feed line (connector) and ideal line, solving the phase constant frequency limit, stopping the constraints bound to the higher mode propagations and improving the accuracy level when the frequency range has increased. The technique is based on the use of the sum of two different lengths of the cell by removing the first value of the phase constant in the frequency range of interest when it is negative. This new technique can be easily implemented; its focus is not on iterative principles, but on the use of the constant propagation of a Quasi-TEM mode of the transmission-line. The bio-food industry (semolina), environmental field (palm tree) and building trade (aquarium sand) were used to test the validity of the technique in 2-20 GHz.

Human perception of vibration is very subjective parameter which depends among others on age, sex or even nationality. There are three main methods of assessment of human perception of vibration according to national standards which differ from each other. All three methods are clearly described in this paper and their advantages and disadvantages are shown. Evaluation methods are helpful in diagnosis and design of the building when they are used properly. One of interesting aspect of quality of measurements is localization of measurement points. The choice of localization of measurement points could have significant influence on result of evaluation of human response to vibration. International and national standards are compatible in this matter – measurement points should be localized in the place of human vibration perception. It means that should be located in the middle of the floor. Sometimes it is difficult to determine the exact center of the floor, especially when building has irregular construction. In this paper influence of localization of measurement point on human perception of vibration is investigated and center zone in which measurement results are proper is determined. In-situ measurements were made to investigate the problem of localization of human vibration perception in buildings.

The issue of an aging population is becoming increasingly acute in Taiwan; in 2018, seniors comprised over 14 % of the total population. The quality of care for senior citizens hinges on the ability of long-term care facilities to create comfortable living spaces while ensuring energy efficiency by reducing electricity consumption, thereby providing them with an environment for aging in an active and positive way. This study proposes a new heat pump system that offers a cold source in the summer and a heat source in the winter. In addition, the air-conditioning and ventilation rates required for comfort in indoor living spaces are established to ensure the high quality of the care spaces in these types of institutions. The results after installation of the heat pump system were as follows: (1) Performance of the heat pump system: the inlet temperature of the heat pump chilled water was maintained at 7-10 °C, and the outlet temperature, at 42-54 °C. (2) Energy efficiency: Based on a 95 % confidence interval, the average annual electricity consumption was 32.65 kwh/day, which was 32.65 % of the prior consumption level; the reduction of 67.35 % is comparable to those of most heat pump systems. (3) Improvement of the indoor environment: In the hottest scenario, the indoor temperature was reduced by 3 °C and the relative humidity to 55-65 %, which fall within comfortable ranges. After the heat pump system was introduced, significant improvements in ventilation, air quality and comfort were noted, as well as significant improvement in average total satisfaction scores. All improvements reached statistical significance. The overall objective of the system is to enhance the environmental quality in long-term senior care facilities and make them healthier and more energy efficient.

This paper presents evaluation of vibroacoustical requirements in the context of impact and airborne sound insulation in hotel building. This building represents traditional wooden architecture present in southern Poland. Similar structures can be found all around Europe in mountainous areas. Due to fact that there are little information about acoustic conditions of such buildings, this paper gives measured values of sound insulation of typical solutions used in this architecture. In order to define if requirements of current polish standard PN-B-02151-03:2015 for hotel buildings are met, impact sound level and airborne sound insulation of representative partitions were measured. Measurement conducted in presented building shows issues connected with non-sufficient airborne sound insulation of internal partitions – timber log walls. Due to its low mass and, in simplification, homogenous structure, its sound insulation is far from meeting requirements. Considering timber structural ceiling and reinforced concrete floor present in hotel building requirements of impact sound level and airborne sound insulation are met. The solution of weak acoustic conditions of walls is proposed as plasterboard pre-wall with mineral wool inside.

This paper describes the soil-structure interaction (SSI) effects to the Nuclear Power Plant (NPP) structure with reactor VVER-1200/491 PWR. The simplified 1D and numerical 3D FE models of the layered subsoil are investigated. The methodology of the calculation of the frequency dependent complex functions of the soil stiffness and damping is presented.