Large venues and auditoriums are commonly associated with their astounding architecture. Their acoustic quality is an essential factor in its qualification as a great and functional, or a badly designed place. However, acoustics is often overlooked during the design stage of a building due to the complexity and high cost of the measurements involved. For this reason, it is important to explore more accessible ways to implement acoustics evaluations. The aim of this work is to compare typical experimental measuring methods and the use of mobile devices to assess the acoustic quality of a room. These measurements are contrasted with the software simulation of the same acoustical space. The results show that the mobile system can be used for professional measurements with low restrictions in the frequency range of interest of this study (90 Hz to 4000 Hz).

This study explains water quality in terms of seven heavy metals in the Upstream Citarum River and analyses human health risk (non-carcinogenic risk) for adults and children. Water samples were collected from five sampling locations along the Upstream Citarum River, i.e. from Majalaya Sub-District to Dayeuhkolot Sub-District. The contents of heavy metals were analysed by the Atomic Absorption Spectrometer (AAS) variant 240 FS. The results of the analysis showed that the pollution index value, which was categorised as slightly polluted from the highest to the lowest value, was as follows: location 4 (4.220) > location 1 (3.764) > location 2 (3.219) > location 5 (2.967) > location 3 (2.800). Values of the hazard index ( HI) for adults and children were as follows: Pb > Cr > Cd > Zn > Ni > Co > Cu. Pb and Cr have HI values greater than 1. This indicates that these metals can have a negative impact on public health. The HI in the ingestion pathway was greater than that of the dermal pathway, and the HI value for children was greater than that for adults. Further research is needed regarding the health risks from groundwater around the area which is used directly by the community because river water and groundwater systems are interconnected through streambeds.

The paper concentrates on seasonal and spatial variations of sub-daily water temperature dynamics in lowland agricultural streams. Temperature monitoring was carried out in 24 sampling sites distributed along the tributaries of the Wkra River during the hydrological year 2021. Statistical analysis of the obtained data documented the highest water temperature dynamics in the morning, from 5:00 to 9:00 CEST, while the lowest – from 14:00 to 18:00 CEST. Seasonally, greater water dynamics were noted in the winter, expressed by a coefficient of variation reaching up to 100%. Spatially, the highest dynamics occurred in sites with the lowest proportion of riparian vegetation, while the lowest dynamics was related to higher catchment area. In the winter, the minimum daily values were recorded most frequently in the morning hours, while maximum values in the afternoon. A similar pattern was observed in the summer, but with much lower dispersion of the relative frequencies. It was found that in the winter, the dominant influence on temperature dynamics was exerted in the upstream catchment area, while in the summer, a negative relationship with riparian shade was marked. The findings suggest that the presence of riparian vegetation reduces diurnal dynamics of water temperature and is simultaneously extremely important in prolonging the duration of optimum fluctuation, responsible for the proper development of poikilothermic organisms.

A DIRECT APPROACH to the problem of the separation of elastic strain energy in the case of generally anisotropic materials is described in the present work. It is based on a simple analysis of the strain tensor into a spherical and a deviatoric one. A definition of dilatational and distortional elastic strain densities is introduced, based on the consideration of the geometrical response of a material. Through the generalized Hooke's law, analytic expressions are obtained for the generally anisotropic materials. The present results coincide with the only available in the literature data for anisotropic materials with cubic symmetry. In addition, an application for transversally isotropic materials is presented.

Twelve mineral elements and total ash were examined in regard to the possible use as the estimators of digestibility of natural food in Antarctic seals. Four of them: phosphorus, calcium, copper and zinc have proved to give most reliable results. The estimated total dry mass and organic matter digestibilities of fish food in Weddell seals (Leptonychotes weddelli (Lesson)) averaged 82 and 91%, while the corresponding values for krill eaten by crabeaters (Lobodon carcinophagus (Hombron and Jaequinot)) and leopard seals (Hydrourga leptonyx (Blainville)) reached approximately 87 and 91%, respectively.

In the present work, amine based extractant and its mixture with cationic and solvating extractants were tested for the extraction of HCl from chloride solution containing Al(III). The chloride feed solution resulted from the leaching of spent HDS (hydro-desulfurization) catalysts. For this purpose, amine extractants, such as TOA (trioctyl amine), Alamine 336 (a mixture of tri-octyl/decyl amine), Alamine 308 (tri-isooctyl amine), and TEHA (tri 2-ethylhexyl amine) were used and the extraction and stripping behavior of HCl was compared. The extracted HCl was easily stripped from loaded TEHA phase, when compared with the other tested tertiary amine system. Solvent extraction reaction of HCl by TEHA was determined from the extraction data. Unlike TOA and Alamine 336, adding cationic extractant to TEHA had negligible effect on the extraction and stripping of HCl. In our experimental ranges, no Al was extracted by amines and pure HCl was recovered. MaCabe- Thiele diagrams for the extraction and stripping of HCl by TEHA were constructed.

Swing-up control of a single pendulum from the pendant to the upright position is firstly surveyed. The control laws are comparatively studied based on swing-up time from a given initial state to the upright position. The State Dependent Riccati Equation is found effective for designing the swing-up control law under saturating control input. The control law is extended to a linear combination of sine function of the angle and the angular velocity, and a variable structure control with a sliding mode given by the linear combination. Making the swing-up time correspond to a colour, which is similar to the Fractal analysis, colour maps of the swing-up time for given control parameters and initial conditions yield interesting Fractal-like figures.