OVERVIEW OF RESEARCH RESULTS OF THE INFLUENCE OF GRAIN SIZE ON BEAMS OF DIFFERENT STRUCTURES OF CONCRETE BY INTERPOLATION

In order to research the influence of the dimensions there have been used the samples of slotted beams on two supports and loaded by force capacity of P = 200 kN and the sensitivity of 100 N fractured (load cell), in the middle, deformations were measured at the point of load and the top of each slot of 50 mm with the sensitivity instrument of 100x10-6 mm LVDT (Tokyo Sokki Kenkyujo Co.SDP-50C). During load all deformations are directly stored with the data logger (30 channels Bucem) that is constantly connected to the computer. The thickness of all samples is constant t = 4 cm and the other two dimensions of height h and length L are changed proportionally. For testing are used three different sizes of the beams and from each sizes are used the three samples. To a mixture of concrete were used two aggregate fractions. A large fraction is 4.76 to 10 mm, smaller fraction is 3 to 4,76 mm. First, sand is put into a mixer, followed by gravel and cement in the dry state and this is going to be mixed for about 2 minutes, after that, the water is added and mixing is going to be carried out for about 2 minutes. From the same samples were set aside the 3 samples in the molds of cylindrical forms with a diameter of 150 mm and a height of 300 mm to determine the brand of concrete. There was used the portland cement (350)

A REVIEW OF INTELLIGENT TUTORING SYSTEMS IN E-LEARNING

An ITS (Intelligent Tutoring System) is a complex, integrated software system that applies the principles and methods of artificial intelligence (AI) to the problems and needs of teaching and learning. They allow searching the student level of knowledge and learning strategies used to increase or correct the students' knowledge. They are intended to support and improve the teaching and learning process in a selected area of knowledge while respecting the individuality of the learner. In the paper a review of intelligent tutoring systems (ITS) is given from the aspect of their application and usability in modern learning concepts

Analysis of the Existence of Size Effect on Different Concrete Types

AbstractThe paper analyzes research on the formula proposed by Bazant, where the existence of size effect is shown. The beams made of different types of concrete loaded at three points, with a slot in the middle of the beam, were experimentally burdened to the point of fracture. The fracture energy (Gf) and the characteristic length in the fracture zone (cf) were determined. For the experiment beams of common, high-quality, lightweight concrete and concrete with steel fibers were used. As the fifth sample ordinary concrete with a change in the width of the bearing under load was made. The maximum size of aggregate grain for the concrete is 10mm. The beams for the experiment were of three different sizes, and three samples of each size. A total of 45 beams were used. Cross-section of beams was changed proportionally

COMPARATIVE ANALYSIS OF THE INFLUENCE OF SIZE ON THE BEAMS OF DIFFERENT STRUCTURES OF CONCRETE

Application of fracture mechanics at design of RC buildings will provide significant benefit. It will contribute that different size of premises to have the same security. In this way, the security and the cost of construction will be enhanced. There will exist a greater possibility of applying new designs and materials. Especially in large RC buildings, as well as in high-strength premises, the premises made of concrete with the steel fibers, prestressed concrete, large concrete dams, nuclear power plants, the facilities that require high safety, whose damage can cause a disaster, the application of fracture mechanics is of great significance. The impact of size, which relies on mechanical fracture can be defined as the theory of fracture which for the design of RC elements take into account resistance and energy of fracture

Study of Fly Ash in Making Cementitious Composites

Applications of fly ash in building industry have very important and relevant problems of origin which are discussed in this paper. Authors have performed tests on mortar, plain concrete and Self Compacting Concrete (SCC) specimens. Experiments showed satisfactory results concerning possible application of fly ash as admixture for cementitious composites. Experimental research was conducted in the Laboratory for materials at the Faculty of Civil Engineering, University of Belgrade

Overview of Sustainable Cementitious Composites Properties with Added Recycled Rubber

The paper is focused to the properties of cementitious composites such as: mortar, ordinary concrete and self-compacting concrete made by means of recycled rubber granulate as a partial replacement for commonly used aggregate. This paper, together with the results of authors' own experimental research on rubberized cementitious composites is presented in detail. The comprehensive conclusion suggests that this type of material can be successfully applied in many fields of engineering practice, thanks to its sustainability, elasticity and durability

Epidemiologic Characteristics of Children with Diabetic Ketoacidosis Treated in a Pediatric Intensive Care Unit in a 10-Year-Period: Single Centre Experience in Croatia

Background and Objectives: The incidence of severe and moderate forms of DKA as the initial presentation of type 1 diabetes mellitus (T1D) is increasing, especially during the COVID-19 pandemic. This poses a higher risk of developing cerebral edema as a complication of diabetic ketoacidosis (DKA), as well as morbidity and mortality rates. The aim of this study was to determine the trend and clinical features of children treated in the last 10 years in the Pediatric Intensive Care Unit (PICU) due to the development of DKA. Materials and Methods: This retrospective study was performed in the PICU, Clinical Hospital Centre Rijeka, in Croatia. All children diagnosed with DKA from 2011–2020 were included in this study. Data were received from hospital medical documentation and patient paper history. The number of new cases and severity of DKA were identified and classified using recent International Society for Pediatric and Adolescent Diabetes (ISPAD) guidelines. Results: In this investigation period, 194 children with newly diagnosed T1D were admitted to our hospital: 58 of them were treated in the PICU due to DKA; 48 had newly diagnosed T1D (48/58); and ten previously diagnosed T1D (10/58). DKA as the initial presentation of T1D was diagnosed in 24.7% (48/194). Moderate or severe dehydration was present in 76% of the children at hospital admission. Polyuria, polydipsia, and Kussmaul breathing were the most common signs. Three patients (5.2%) developed cerebral edema, of whom one died. Conclusions: During the investigation period a rising trend in T1D was noted, especially in 2020. About one quarter of children with T1D presented with DKA at initial diagnosis in western Croatia, most of them with a severe form. Good education of the general population, along with the patients and families of children with diabetes, is crucial to prevent the development of DKA and thus reduce severe complications