Dynamic Analysis of Rockets Launcher

This paper deals with dynamic analysis of rockets launcher on a moving vehicle. Mechanical model of a launch rail system with a rocket is represented as a set of solid bodies and deformable elements with a damped elastic support. These launch rail systems enable to fire rockets of different weights and geometric configurations. Unlike them, today´s multiple rocket launcher systems are located in containers. Movement of this type of mechanical system is described with three defined coordinates: movement of a rocket on a deformable ramp, curvature of the top of a deformable ramp and an angle of rotation of the ramp around its longitudinal axis. Mathematical model of the whole system, including rockets launcher and vehicle, represents a system of five nonlinear, nonhomogeneous differential equations of second order. This system is transformed to a system of 10 differential equations of the first order, suitable for numerical solving through the software package MATLAB. Rocket launcher designers can find the obtained simulation and experimental results, represented in a graphical form which is very useful during the development of a new and modification of existing constructions

Performance Analysis of 5G Transmission over Fading Channels with Random IG Distributed LOS Components

Mathematical modelling of the behavior of the radio propagation at mmWave bands is crucial to the development of transmission and reception algorithms of new 5G systems. In this study we will model 5G propagation in nondeterministic line-of-sight (LOS) conditions, when the random nature of LOS component ratio will be observed as Inverse Gamma (IG) distributed process. Closed-form expressions will be presented for the probability density function (PDF) and cumulative distribution function (CDF) of such random process. Further, closed-form expressions will be provided for important performance measures such as level crossing rate (LCR) and average fade duration (AFD). Capitalizing on proposed expressions, LCR and AFD will be discussed in the function of transmission parameters

ANALYSIS OF METEOROLOGICAL AND AGRICULTURAL DROUGHTS IN SERBIA

Abstract: Drought represents a combined heat-precipitation extreme and has become an increasingly frequent phenomenon in recent years. In order to access the entire analysis of drought, it is necessary to include the analysis of several types of drought. In this paper, impacts of meteorological and agricultural drought were analyzed across the Standardized Precipitation Index (SPI) and Agricultural Rainfall Index (ARI) on the territory of Serbia for the period from 1980 to 2010. For both types of drought, year 2000 is notable as the year when most of the observed stations had the highest drought intensity. It was found that meteorological drought for year 2000 has a higher intensity in the central and southeastern parts of the country, as well as in the north. Of all the stations, the highest intensity of meteorological drought was observed at Loznica station in 1989. Agricultural drought in 2000 had the lowest intensity in western Serbia.   Key words: drought, meteorological drought, agricultural drought, Standardized Precipitation Index, Agricultural Rainfall Index, Serbia.

Long-Term Precipitation Analysis and Estimation of Precipitation Concentration Index Using Three Support Vector Machine Methods

The monthly precipitation data from 29 stations in Serbia during the period of 1946–2012 were considered. Precipitation trends were calculated using linear regression method. Three CLINO periods (1961–1990, 1971–2000, and 1981–2010) in three subregions were analysed. The CLINO 1981–2010 period had a significant increasing trend. Spatial pattern of the precipitation concentration index (PCI) was presented. For the purpose of PCI prediction, three Support Vector Machine (SVM) models, namely, SVM coupled with the discrete wavelet transform (SVM-Wavelet), the firefly algorithm (SVM-FFA), and using the radial basis function (SVM-RBF), were developed and used. The estimation and prediction results of these models were compared with each other using three statistical indicators, that is, root mean square error, coefficient of determination, and coefficient of efficiency. The experimental results showed that an improvement in predictive accuracy and capability of generalization can be achieved by the SVM-Wavelet approach. Moreover, the results indicated the proposed SVM-Wavelet model can adequately predict the PCI

Modern Safety Aspects of Business Database

As the business database stored and kept large amounts of mostly confidential business or personal information, often represent a great value for the organization in terms of business. This is the main reason business database requires a high degree of safety. Particular attention should be paid to protect them from malicious activities, from unauthorized access through the Internet as well as from malicious use by the employees themselves in the business system. System for safe management business databases are an important tool in raising their productivity. The ability to secure storage, access and management of data in such systems is becoming critical for any business system. For that reason, safety aspects of business databases are located in the center of information systems strategy of each company

EFEKTI UTICAJA MODELA SOLARNE RADIJACIJE NA PRORAČUN REFERENTNE EVAPOTRANSPIRACIJE

The crop evapotranspiration has the great effect on defining and planning of water resources. The estimation of evapotranspiration depends on various climatic parameters. In this study, the analysis of the effect of solar radiation (Rs) on daily reference evapotranspiration (ET0) was conducted. The FAO-56 Penman-Monteith method (FAO-56 PM) was used for the estimation of ET0 in Serbia at eight meteorological stations for the period 1980-2010. The Rs was estimated using the ten one-parameter global solar radiation models. The ET0 with Almorox and Hontoria model 1 had the smallest deviation related to the ET0 with Angstrőm-Prescott (AP) model, and ET0 with Toğrul et al. model 2 and Rietveld model had the greatest deviation from ET0 with AP model. Evapotranspiracija useva ima veliki uticaj na definisanje i planiranje vodnih resursa. Proračun evapotranspiracije zavisi od različitih klimatskih parametara. U ovom radu je sprovedena analiza uticaja solarne radijacije (Rs) na dnevne vrednosti referentne evapotranspiracije (ET0). Za proračun ET0 je korišćen FAO-56 Penman-Monteith metod (FAO-56 PM) u Srbiji za vremenski period 1980-2010. Rs je određen upotrebom deset jednoparametarskih globalnih solarnih radijacionih modela. ET0 dobijena korišćenjem Almorox and Hontoria model 1 za proračun Rs daje najmanja odstupanja u odnosu na ET0 sa Angstrőm-Prescott (AP) modelom a ET0 izračunanta uz pomoć Toğrul et al. model 2 i Rietveld modela daje najveća odstupanja od ET0 sa AP modelom

Prediction of annual precipitation on the territory of south Serbia using Markov chains

Prediction of precipitation is one of the important factors that affect the sectors such as industry, agriculture, environmental protection, and their related fields. The stochastic method based on a Markov chain model is used in the paper to predict the annual precipitation in the territory of South Serbia for the period 2009-2013. For this purpose, the precipitation data rainfall recorded on the four synoptic stations were used for the period 1980-2010. [Projekat Ministarstva nauke Republike Srbije, br. TR 37003: Razvoj hidroinformacionog sistema za praćenje i ranu najavu suša

Analysis of trends in reference evapotranspiration data in a humid climate

<div><p></p><p>Statistically significant FAO-56 Penman-Monteith (FAO-56 PM) and adjusted Hargreaves (AHARG) reference evapotranspiration (ET₀) trends at monthly, seasonal and annual time scales were analysed by using linear regression, Mann-Kendall and Spearman’s Rho tests at the 1 and 5% significance levels. Meteorological data were used from 12 meteorological stations in Serbia, which has a humid climate, for the period 1980–2010. Web-based software for conducting the trend analyses was developed. All of the trends significant at the 1 and 5% significance levels were increasing. The FAO-56 PM ET₀ trends were almost similar to the AHARG trends. On the seasonal time scale, for the majority of stations significant increasing trends occurred in summer, while no significant positive or negative trends were detected by the trend tests in autumn for the AHARG series. Moreover, 70% of the stations were characterized by significant increasing trends for both annual ET₀ series. </p><p><b>Editor</b> Z.W. Kundzewicz; <b>Associate editor</b> S. Grimaldi</p><p><b>Citation</b> Gocic, M. and Trajkovic, S., 2013. Analysis of trends in reference evapotranspiration data in a humid climate. <i>Hydrological Sciences Journal</i>, 59 (1), 165–180.</p></div