On the Alekseev-Gr\"obner formula in Banach spaces

The Alekseev-Gr\"obner formula is a well known tool in numerical analysis for describing the effect that a perturbation of an ordinary differential equation (ODE) has on its solution. In this article we provide an extension of the Alekseev-Gr\"obner formula for Banach space valued ODEs under, loosely speaking, mild conditions on the perturbation of the considered ODEs.Comment: 36 page

The Effect of Winding Angle on Unwinding Yarn

In the production of fabric, the unwinding of thread occurs in the warping and weft insertion processes. In order to achieve low and constant tension of thread or yarn it is necessary to optimize the process of unwinding. Computer simulations are now in use for this purpose, so it is important to obtain a mathematical description of yarn motion. This article is devoted to the derivation of boundary conditions that considerably affect the form of the balloon. In this way, a mathematically well defined model of yarn unwinding will be obtained which could be solved by using the tools of numerical mathematics. The unwinding of yarn from an optimally designed package can be simulated and this knowledge can be used to find an optimal design of packages

Simulations of Yarn Unwinding from Packages

Yarn unwinding from stationary packages has an important role in many textile processes. In order to achieve high unwinding velocity that can lead to increased production rate, it is necessary to develop packages with a suitable geometry, dimensions, and winding type. The optimal design of the package leads to an optimal form of the balloon and low and uniform tension at high unwinding speed. In this work I will show a simple mathematical model which can be used for simulating the unwinding process. Using experimental values I will find a relation between the angular velocity of the yarn around the axis and the tension. This will allow me to calculate the oscillations of the tension in the yarn during the unwinding from packages of different geometries and with different winding angles. I will find an optimal design for a package of a new generation

Radno mjesto - radnik - okoliš. ekspertni sistem

In the expert system described stresses due to the workplace and the life environment are represented by characteristics, which are graded from O to 5. The same is true of capabilities of the man. The algorithm looks for the compatibility of one with the other. Examples of characteristics, the function of the certainty factor and of steps of examination depth are shown, with particular reference to the cardiovascular subsystem. The expert system “Workplace - Worker - Environment- is proposed” to serve as a basic tool in occupational health care.U opisanom ekspertnom sistemu stresovi kojima je radnik izložen na radnom mjestu i u životnom okolišu prikazani su pomoću karakteristika koje se ocjenjuju brojem od O do 5. Na isti način vrednuju se i radnikove sposobnosti. Algoritmom se traži kompatibilnost jednih i drugih. Dani su primjeri karakteristika, uloga faktora sigurnosti i stupnja dubine ispitivanja, s osobitim osvrtom na kardiovaskularni podsistem. Ekspertni sistem Radno mjesto - radnik - okoliš može poslužiti kao osnovno sredstvo rada u službi medicine rada

Corrosion Detection and Surface Repair with Coatings on Condensate Storage Tanks Internal Surfaces

In the Nuclear power plant Krško, there are two single hull condensate storage tanks with floating diaphragm each containing up to 757 m3 of demineralized water. The main purpose of these two storage tanks is to provide a capacity of cooling water for cooling the reactor coolant system via steam generators with the use of auxiliary feedwater pumps. This is a very important function from the safety point of view and that is the reason that both storage tanks are listed as safety class 3 components. It is also possible to fill up the condensate system if other means are not available. Condensate storage tanks are subject to periodic testing and periodic inspections to determine the condition of the components. Both tanks are in operation since the start-up of the powerplant, are located outside, and are exposed to different degradation processes. There was a concern that the tanks are leaking because there were often small puddles of water near the tanks. There were no changes in the levels of tanks. The design of tanks is a single hull, so there is no indication if a small leak is present. In the outage 2018, both tanks were emptied and examined with NDE methods to find any corrosion damage of bottom plates and any untight spots on adjacent welds. The article is about the NDE methods that were used (Magnetic Flux Leakage, Ultrasonic and Vacuum Box inspection) to determine the condition of the floor plates and adjacent welds as well as the process of internal surface reparation with coatings. Process of coatings qualification for use in safety class components is also explained: dedication process for material up-grade from non-safety related to safety-related because CY tank linings are classified as safety-related according to RG 1.54, rev 2 and corresponding ASTM standards and NEK technical specification SP-A5001. All activities for surface repair with coatings shall comply with safety-related requirements. Also, extensive immersion tests with selected and specially defined parameters were performed in NEK chemical laboratory in order to select the most suitable coating system for surface repair of CY tank floor lining. Further details concerning immersion tests are presented below