Computer Aided Tolerancing (CAT) platform for the design of assemblies under external and internal forces

Due to the stochastic nature of manufacturing processes, the functionality of mechanical assemblies is subject to variation defined by tolerances and manufacturing process characteristics. In many assemblies, functionality is also dependent on external and internal forces. Numerous Computer Aided Tolerancing (CAT) tools have been proposed that address tolerance analysis problems in complex mechanical assemblies; however current tools do not accommodate a general class of problem where the functionality of a design is fundamentally dependent on the effects of external and internal forces. This research addresses the limitation of CAT tools to accommodate assemblies under loading by developing a tolerance analysis platform which integrates CAD, CAE and statistical analysis tools using Process Integration and Design Optimisation (PIDO) software capabilities. The platform extends the capabilities of traditional CAT tools by enabling tolerance analysis of assemblies in which assembly characteristics are dependent on external and internal forces. To demonstrate the capabilities of the developed platform, examples of tolerance analysis problems involving external forces (compliance) and internal forces (multi-body dynamics) are presented.     

Security Analysis of the Efficient Chaos Pseudo-random Number Generator Applied to Video Encryption

Recently, chaos based pseudo-random number generator (PRNG) for video encryption was proposed. Security analysis presented in this paper reveals serious problems. Chaotic maps used in analyzed PRNG do not enhance its security due to a considerable number of initial values that lead to fixed points. Also, based on 6 known iterations, an attacker can reconstruct a secret key used in the working stage of the analyzed PRNG based on attack whose complexity is much smaller than the estimated key space. Therefore, security of the analyzed PRNG is much lower than expected and it should be used with caution. Some potential improvements of the analyzed PRNG are proposed which could eliminate perceived shortcomings of the original version.     

Correlations between submission and acceptance of papers in peer review journals

Scientometrics - This paper provides a comparative study about seasonal influence on editorial decisions for papers submitted to two peer review journals. We distinguish a specialized one, the...     

GPS telemetry of energetic-technical and technological parameters at open pit mines

Application of GPS in mining and geology has proved to be of ever increasing importance since recently. GPS is used for positioning both researching and exploitation drill holes, mining facilities, equipment, machines, when monitoring slopes and falls, mining facilities dimensioning, navigation of machines, roads tracing, etc. The paper presents a pilot system for surveillance and monitoring of energetic and technological parameters at open pit mines, developed at the “Jazovnik” open pit mine for experimental purposes. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 90–94, July–August, 2008.     

A correlation to describe interfacial heat transfer coefficient during solidification of Al–Si alloy casting

A thin wall Al–9 wt.% Si alloy casting was made in a sand mold prepared by CO₂ process. The thermal history obtained from the experiment was used to solve an inverse heat conduction problem (IHCP). The IHTC was estimated by an iterative algorithm based on the function specification method. Acquired IHTC values are given as a function of time and as a function of the casting surface temperature at the interface. It has been found that pattern of IHTC variation with casting surface temperature can be described by an equation which has been proposed as a new correlation model. In order to verify broader applicability of the proposed correlation, its use is demonstrated on the IHTC results taken from the literature.     

Impurity removal and overall rate constant during low pressure treatment of liquid silicon

The research presented analyzes the effect of low pressure on the amount and reduction of impurity elements in upgraded metallurgical grade silicon. The achieved pressure was 5 kPa in the commercial electro-resistance furnace in the magnesia and mullite refractory material. The chemical composition was determined by ICP-MS method. Elements such as Al, Fe, Mn, Cu or Zn had the highest evaporation rates where higher evaporation was achieved at higher melt temperatures. The overall rate constant was deduced for four melt temperatures indicating high values even for low melt temperatures. The interfacial boundary between Si and mullite refractory showed no dissolution of Al into the liquid Si.     

Improving Energy Efficiency and Reliability in WuR-Based IoT Systems: An Error Correction Approach

Wireless Personal Communications - One of the most suitable option for millimeter-wave integrated circuits and systems implementation is Substrate Integrated Waveguide (SIW) Technology....