Microcalorimeter design for fast-neutron spectroscopy

We are developing microcalorimeters for fast-neutron spectroscopy. The goal is to develop a detector with an energy resolution of 0.1% for 1–20 MeV neutrons with an efficiency of 1%. We discuss the design of such a detector and present the first results of a transition edge sensor based microcalorimeter with a small TiB₂ absorber. The best energy resolution obtained was 5.5 keV FWHM for a total energy deposition of 2.792 MeV by thermal neutrons.     

UMTS RAN Capacity Analysis for Special Events

Special events such as music festivals, sports etc are characterised as “high user density” where user behaviour is determined by the dynamics of the event. This is the reason that it is necessary for a mobile network operator to dimension its network based on maximum expected resource requirements instead on averaged values. Although special events are taking place almost every week, in most cases not enough attention has been paid to the problem of resource dimensioning in the Universal Mobile Telecommunications System networks, and the appropriate cost function to equate the optimal quantities resources has not been developed. It is therefore necessary to be aware that special events networks should be dimensioned with the maximum resource requirements, using distributed antenna system (DAS) where possible, and the consolidated baseband processing resources. Appropriate cost function will be used to describe optimal design that should depend on the number of sectors needed, radio network controller and the overall network capacity. A suitable radio access network (RAN) analysis has been performed and a cost function has been developed in order to create the metrics that can be used for evaluating the cost of dimensioning the RAN in special events. It can be shown based on proposed metrics that 10 % of savings in resources could be achieved by degrading the grade of service less than 1 %.     

Synthesis of starch benzoate in aqueous media

Summary The results of investigating starch benzoate (SB) synthesis in aqueous media are presented in this study. Starch esterification with benzoyl chloride was performed in two steps, the first step being the alkalization of starch and the second step esterification. The influence of the concentration of reactants, reaction medium composition, temperature and time of synthesis on the degree of substitution (DS), degree of swelling in water and thermal stability of the synthesized starch benzoate was investigated. The optimal conditions for the synthesis of starch benzoate with degree of substitution from 0.23 to 1.76 were determined. It was shown that starch benzoate with a DS of 1.76 practically did not swell in water. However, starch benzoate is less thermally stable than native starch probably due to a change in the supermolecular order induced by the esterification reaction. Received: 18 March 2002/Revised version: 18 October 2002/ Accepted: 28 October 2002 Correspondence to Katarina Jeremić     

Piezoresistivity and electro-thermomechanical degradation of a conducting layer of nanoparticles integrated at the liquid crystal elastomer surface

When a liquid crystal elastomer (LCE) is reprocessed with conducting nanosized particles a conducting layer can be formed at the LCE surfaces. Here, two different LCE materials and two different conducting carbon particles were used. These four reprocessed LCEs were investigated when subject to a thermal phase transition and mechanical extension. Here it is shown that the resistance change with strain ('piezoresistivity') for these reprocessed LCEs can be described through lattice percolation and geometrical changes in the LCE shape. The mechanisms and rate of degradation are also described for the conducting layer as a function of the number of electro-thermomechanical strain cycles performed.     

Failure analysis of the combat jet aircraft rudder shaft

This paper analyzes failure causes of the combat jet aircraft rudder shaft (RS) which occurred during the flight mission. A finite element method (FEM), utilized to determine the stress state of the RS subjected to hinge moment ultimate load, resulted in the high stress concentration sites around the rivet holes. The longitudinal crack was initiated from the corrosion pit in the zone of the rivet hole, where the fatigue beach marks were observed. The inner surface of the RS was heavily corroded. Moreover, pitting corrosion has destroyed approximately 50% of the wall thickness. Based on the presented results it was concluded that the failure of the RS had a character of fatigue combined with heavy corrosion. Therefore, it is recommended that the RS should be redesigned; the material changed into more corrosion resistant one and the maintenance procedure changed in order to avoid future similar failures.     

Spectral determination of graphs whose components are paths and cycles

We consider the class of graphs each of whose components is either a path or a cycle. We classify the graphs from the class considered into those which are determined and those which are not determined by the adjacency spectrum. In addition, we compare the result with the corresponding results for the Laplacian and the signless Laplacian spectra. It turns out that the signless Laplacian spectrum performs the best, confirming some expectations from the literature.     

Effects of liquid burn rate catalysts on Rheological Properties of High-Energy Composite Propellants

Effects of several liquid burning rate catalysts on rheological properties of composite rocket propellants on the basis of hydroxy-terminated polybutadiene as a binder and ammonium perchlorate as an oxidizer have been examined. Theoretical explanation of the observed effects of liquid catalysts on certain rheological properties of the mentioned propellants are given. Laboratory procedures for synthesis of used catalysts are described. The results of physico-chemical characterization of synthesized catalyst are also presented.     

The p-hub Model with Hub-catchment Areas,Existing Hubs,and Simulation: A Case Study of Serbian Intermodal Terminals

This paper addresses the problem of optimally locating intermodal freight terminals in Serbia. To solve this problem and determine the effects of the resulting scenarios, two modeling approaches were combined. The first approach is based on multiple-assignment hub-network design, and the second is based on simulation. The multiple-assignment p-hub network location model was used to determine the optimal location of intermodal terminals. Simulation was used as a tool to estimate intermodal transport flow volumes, due to the unreliability and unavailability of specific statistical data, and as a method for quantitatively analyzing the economic, time, and environmental effects of different scenarios of intermodal terminal development. The results presented here represent a summary, with some extension, of the research realized in the IMOD-X project (Intermodal Solutions for Competitive Transport in Serbia).