STRENGTH AND STIFFNESS OF REINFORCED CONCRETE BEAMS MADE ON EXPERIMENTAL COMPOSITION OF A CONCRETE GOODS PLANT

One of the options for optimization in the activities of the construction industry plants is the improvement of the composition of concrete mixtures, which requires control measures to assess indicators that ensure the reliability of operation of concrete and reinforced concrete structures. The strength of concrete in standard control cubes is at the same time the dominant parameter that determines the prospects of changes in production. The presented work presents the results of a comprehensive assessment of experimental concrete on cubes, prisms and reinforced concrete beams.

An experimental investigation of surface roughness in 3D-printed PLA items using design of experiments

This work investigates the effect of 3D-printing parameters on surface roughness in polylactic acid printed material by adopting Taguchi's design of experiments approach. The control parameters under study were: number of shells, printing temperature, infill rate, and printing pattern. As the response, mean surface roughness (Ra) was selected. The control parameters were assigned to an L9 orthogonal array to organize the experiments and obtain the mean surface roughness results. It is concluded that printing temperature is the dominant parameter that affects surface roughness when it comes to 3D printing of polylactic acid material followed by printing pattern, infill rate, and the number of shells.

Experimental Research on Coal and Gas Delay Outburst and AE Characteristics under Conditions of Geostress and Gas Pressure Disturbance

Adopting yellow mud as barrier layer materials, coal and gas delay outburst experiments under conditions of geostress and gas accumulation disturbance were carried out by using self-developed simulation system, to find out roles of geostress and gas pressure played in the process of the delay outburst and ways to predict it, through analysis of variations of gas pressure, and AE characteristics during the process. The results show that after the geostress increased by 0.11 MPa from 1.80 MPa, an outburst occurs, while in gas accumulation situations, the gas pressure increase of 0.27 MPa from 0.67 MPa induces an outburst; hence, geostress is one of the dominant factors impacting an outburst occurrence. The lasting time of the outburst triggering under geostress disturbance is shorter than that under gas accumulation disturbance, while the duration of the outburst development under gas accumulation conditions is longer than that under geostress conditions. Coal seam breakage by geostress is the precondition for an outburst risk, and gas expansion energy is the dominant parameter influencing the duration of the outburst development. The AE signals show distinctive features in different stages of the outburst under geostress disturbance. At the preparation stage of the outburst, the AE signals increase sharply but have a low intensity and then drop to a lower balance level. At the triggering stage, the AE signals become active and increasing until up to the peak where the outburst occurs, and the intensity is highest.

KAJIAN LOKASI POTENSIAL PERUMAHAN DAN PERMUKIMAN DI KABUPATEN PESAWARAN DENGAN SISTEM INFORMASI GEOGRAFIS (SIG)

Pesawaran District, as a new district which was established in 2007, has experienced a rapid growth in population. As the population increases, housing and residential land needs will increase. Therefore, there should be a careful planning in determining the location of housing and settlement development in Pesawaran District. This study aims to: 1) Know the weight for each parameter used in determining the level of potential for a land for the development of housing and residential areas with method AHP 2) Know the potential level of land in Pesawaran District for the development of housing and settlements. The method used is AHP (Analytic Hierarchy Process), while the method by spatial analysis using GIS (Geographic Information System).The results of the study with AHP calculations show that the most dominant parameter is accessibility. The reason is, accessibility will affect the ease of transportation services and affordability of distance. The results of the analysis using GIS resulted in 5 potential locations for the development of residential and residential areas in Pesawaran District which are very potential (13456.50 ha), potential (47941.61 ha), quite potential (47362.11 ha), less extensively potential (16107.09 ha), and no potential (8251.13 ha).

Atmospheric Plasma Spraying of Al2O3 + 13% TiO2 Coatings Using External and Internal Injection System

The ceramic coatings based on mixture of Al2O3 and TiO2 have better properties in comparison to the pure alumina ones. Among many techniques, plasma spraying is very useful method of ceramic coatings manufacturing. In this paper, the results of microscopic, mechanical and tribological properties investigations of Al2O3 + 13 wt% TiO2 coatings manufactured by atmospheric plasma spraying are presented. The cylinder substrates made from stainless steel (X5CrNi18-10) had a diameter equal to 25 mm and thickness equal to 2 mm. The plasma spray experimental parameters included three variables: (i) type of injection system (external or internal), (ii) size of corundum particles for sandblasting and (iii) torch linear speed. The results confirm, that type of injection system is a dominant parameter. Internal injection results in better degree of particles melting, what influences on wear resistance performance, as well as higher values of bond strength.

Niche-inspired synthetic matrices for epithelial organoid culture

Epithelial organoids are now an important tool in fields ranging from regenerative medicine to drug discovery. Organoid culture requires Matrigel, a complex, tumor-derived, extracellular matrix. An alternative completely synthetic matrix could improve culture reproducibility, clarify mechanistic phenomena, and enable applications involving human implantation. Here, we designed synthetic matrices with tunable biomolecular and biophysical properties that allowed us to identify critical gel parameters in organoid formation. Inspired by known epithelial integrin expression in the proliferative niche of the human intestine, we identified an α2β1 integrin-binding peptide as a critical component of the synthetic matrix that supports human duodenal colon and endometrial organoid propagation. We show that organoids emerge from single cells, retain their proliferative capacity, are functionally responsive to basolateral stimulation and have correct apicobasal polarity upon induction of differentiation. The local biophysical presentation of the cues, rather than bulk mechanical properties, appears to be the dominant parameter governing epithelial cell proliferation and organoid formation in the synthetic matrix.

Effect of Load Weight and Starting Height on the Variability of Trunk Kinematics

Trunk kinematic variables have been used to understand the risk of low back injuries in the workplace. Variability in trunk kinematics has not been explored to the same level. In the current study, it was hypothesized that workplace variables (starting height and load weight) would have an impact on the variability in the kinematic variables describing trunk motion. Ten participants performed a repetitive lifting task under four different conditions representing two levels of load weight and starting height. The Lumbar Motion Monitor was used to capture key trunk kinematic variables from the concentric range of lifting motion. The dominant parameter in this experiment was found to be the starting height of the lift which significantly affected the variability of trunk kinematics in sagittal plane. In the transverse plane neither starting height of the load nor the weight of the load were found to influence the variability of trunk kinematics significantly.