Putovanje od St. Petersburga do Moskve ili model gravitacijskog vlaka u Mathcad-u

This paper somewhat humorously shows a physical model of the semi-fantastic idea of an underground tunnel that would connect the two cities, which would be traveled through by the so called gravity train. The idea has existed since Robert Hook first presented it to Sir Isaac Newton. This problem is described by the system of ordinary differential equations. The solution of equation system is obtained numerically using Mathcad applications (with units) and function Odesolve.Ovaj rad na pomalo humorističan način prikazuje fizikalni model polu fantastične ideje podzemnog tunela koji bi spajao dva grada, a kroz koji bi se putovalo tzv. gravitacijskim vlakom. Ideja postoji od vremena Roberta Hooka, koji ju je prvi izložio Sir Isaac Newtonu. Ovaj je problem uz određena pojednostavljenja opisan sustavom običnih diferencijalnih jednadžbi, a rješenje sustava jednadžbi dobiveno je numerički, korištenjem Mathcad aplikacije i naredbe Odesolve

Putovanje od St. Petersburga do Moskve ili model gravitacijskog vlaka u Mathcad-u

This paper somewhat humorously shows a physical model of the semi-fantastic idea of an underground tunnel that would connect the two cities, which would be traveled through by the so called gravity train. The idea has existed since Robert Hook first presented it to Sir Isaac Newton. This problem is described by the system of ordinary differential equations. The solution of equation system is obtained numerically using Mathcad applications (with units) and function Odesolve.Ovaj rad na pomalo humorističan način prikazuje fizikalni model polu fantastične ideje podzemnog tunela koji bi spajao dva grada, a kroz koji bi se putovalo tzv. gravitacijskim vlakom. Ideja postoji od vremena Roberta Hooka, koji ju je prvi izložio Sir Isaac Newtonu. Ovaj je problem uz određena pojednostavljenja opisan sustavom običnih diferencijalnih jednadžbi, a rješenje sustava jednadžbi dobiveno je numerički, korištenjem Mathcad aplikacije i naredbe Odesolve

Active and passive methods for reducing vibrations

Ovaj članak opisuje metode koje se koriste za smanjivanje vibracija na strojevima i konstrukcijama. U uvodnom dijelu je opisan pojam vibracija kao te su navedeni neki uzroci pojave vibracija. U radu su navedene razne metode koje se koriste da bi se kontrolirala razina vibracija. Opisan je piezoelektrični efekt i mogućnosti korištenja piezomaterijala pri aktivnoj kontroli vibracija.This article describes methods used to reduce vibrations. The term vibration is described in the introduction along with some of the origins of vibrations. Various methods used to control the level of vibrations are described in the article. Piezoelectric effect is described together with the possibilities of using piezo materials for active vibration control

Značajke nekih Web 2.0 alata

Options of some WEB 2.0 applications are described and some ways of their application in scientific work and research are proposed. An average user is provided with easier access to Online Collaboration tools. The main problems that appear while searching the Internet are highlighted, which has become the main source of all types of information. The advantages of using some WEB 2.0 applications in searching and sharing data are shown. A proposal of classifying WEB 2.0 applications according to their main usage is presented. Free features of some WEB 2.0 applications are listed according to the proposed classification. Furthermore, their main characteristics are described and instructions on how to use them are provided. Some examples of applications in scientific work, research and practical sessions are mentioned as well.Opisane su mogućnosti nekih WEB 2.0 aplikacija i predloženi su neki načini njihove primjene u znanstveno-istraživačkom radu. Prosječnom korisniku su približene mogućnosti alata za mrežnu suradnju (eng. Online Collaboration). Istaknuti su glavni problemi koji se javljaju prilikom pretraživanja interneta koji je postao glavni izvor svih vrsta informacija. Prikazane su prednosti korištenja nekih WEB 2.0 aplikacija prilikom pretraživanja i razmjene podataka. Predstavljen je prijedlog podjele WEB 2.0 aplikacija prema njihovoj glavnoj namjeni. Navedene su besplatne značajke nekih WEB 2.0 aplikacija prema predloženoj podjeli,opisane su i njihove glavne karakteristike te su dane upute za korištenje. Spomenuti su i neki primjeri aplikacija u znanstveno-istraživačkom radu i praktičnoj nastavi

MathCad za inženjere: optimizacija rješenja problemskog zadatka iz dinamike krutih tijela

In this paper, an example problem was used to demonstrate the application of Mathcad in solving the tasks of the dynamics of rigid bodies. The task was to determine angular acceleration for a given moment and the moment value at minimum acceleration, which makes this problem an optimization problem. Classical analytical solution of the problem is obtained using the D\u27Alembert principle. Mathcad code is given by which the solution is obtained. Functional dependence of angular acceleration to frictional moment is determined and final solution is calculated by the minimization function. Comparison of optimization solutions to classical solution confirmed the effectiveness of this method of problem solving. For this procedure Mathcad symbolic functions were used.U radu je na problemskom zadatku prikazana primjena MathCad-a u rješavanju zadataka iz dinamike krutih tijela. U zadatku je potrebno odrediti koliko je kutno ubrzanje za zadani moment i koliki je moment za minimalno ubrzanje, stoga ovaj problem predstavlja optimizacijski problem. Klasično analitičko rješenje zadatka je postavljeno koristeći D\u27Alembertov princip te je dana sintaksa MathCad koda kojim je dobiveno rješenje. U nastavku je za određivanje momenta definirana funkcija ovisnosti kutnog ubrzanja o momentu te je minimizacijom odredjen rezultantni moment. Usporedba rješenja optimizacije s klasičnim rješenjem potvrdila je učinkovitost ovog načina rješavanja zadatka. Za ovaj postupak su korištene MathCad simboličke funkcije

An Overview and Efficiency Analysis of Dominant Frequencies Estimation Methods with the Application of DIRECT Global Minimization Method

This report discusses the application of the following methods that are used to calculate maximum frequency of a spectrum: parabolic, modified parabolic by Rife and Vincent, the method according to Quinn from 1994 and the method according to Quinn from 1997. After introducing DIRECT global minimization method, the results obtained using previously mentioned methods are compared with the results obtained using DIRECT global minimization of the Lipschitz function. Determining vibration frequency and comparing to previously collected data or knowledge base data is a common procedure. In engineering practice it is often necessary to determine not one, but several so-called dominant frequencies or local maxima; the procedure is sometimes called multi peak detection and here we propose an algorithm for computerised multi peak detection

The Application of Virtual Tools in Teaching Dynamics in Engineering

Student success in Dynamics, a core subject in Mechanical Engineering courses, requires conceptual understanding of complex systems. Dynamics covers motion of particles and objects, and usually relies on 2 dimensional images and/or written descriptions to explain models and problems. This paper explores the value of visual representation of Dynamics problems with an assumption that it would facilitate student understanding of the content. Two approaches were applied for representation of Dynamics problems with the premise of Bring Your Own Device (BYOD): used with augmented reality and web animation activities. Responses from students and reflection from lecturers were collected and reviewed in relation to the applicability and the ease of use. Students and lecturers both appreciated the benefits of visual representation of complex models, and the possibility of manipulating with virtual objects. Lecturers also appreciated the easy access and use of tools during the class

The making of detonator pressing tool

U članku je objašnjen postupak uprešavanja čahure kod izrade detonatora i opisan je princip rada alata za uprešavanje. Opisan je postupak izrade cjevčice koja aktivira detonator. U uvodnom dijelu je objašnjena funkcija detonatora te je ukratko opisan razvoj detonatora.Pressing procedure of detonator sleeve production and the principle of detonator sealing process are described in this paper. The production process of detonator tube is shortly described. The function and evolution of detonators are shortly described and explained in the introduction