This paper describes a methodology for transmission tower 3D modelling. The task was to develop a virtual 3D model, corresponding to the real structure, which will be subjected to structural analysis in ANSYS software. The process of 3D modelling is crucial for this kind of computer analysis. It requires precise key point coordinates defining. Not only the important points of the structure, but also the points of interest for the future structural analysis have to be defined. This means that model developer should be familiar with the structural analysis so he could form adequate key points in advance. The main point of the experiment concept is to determine dynamic behaviour of the structure, exposed to a known load. Truly correlated 3D model, with verified geometric, static and dynamic properties offers the opportunity to predict the structure behaviour under loads that can hardly apply on a living structure (extreme overloads, complex loads, and harsh ambient condition).

Prestressed concrete is a highly being used material in the construction of strategic and important structures such as nuclear containments, bridges, storage structures and military bunkers. It is highly durable, fire and corrosion resistant and nonporous. In order to study the influence of prestresing on the ballistic characteristics of concrete targets ballistic experiments have been carried out against ogival nosed (3 CRH) hard steel projectiles. The projectile of 0.5 kg mass were normally impacted on 80 mm thick presstressed concrete targets of plan size 450 mm x 450 mm. The unconfined compressive target strength of concrete was designed 48 MPa. An initial stress of 10% magnitude of compressive strength was induced by 4 mm diameter high tensile strength (1700 MPa) steel wires in prestressed concrete targets. A grid of 8 mm diameter steel bars were inserted in the reinforced and prestressed concrete targets to enable the straight comparison between these concretes. The prestressing in concrete has been found to be effective in reducing the volume of scabbed material as well as the ballistic resistance of prestressed concrete targets. The ballistic limit of prestressed concrete with 10% induced stress was found to be 10.2 % higher than that of the reinforced concrete and 14% higher than the plain concrete target, respectively.

This paper presents the development of a model for forecasting and decision-making by applying logistic regression. The prediction of professional choices for graduates has been verified on the sample of 159 graduates. Predictor variables are grouped in nine input variables and the data collected from the Unique Education Information System database. Professional choices of graduates after finishing vocational school are grouped into three output variables and the data collected in the survey. The obtained results show that the application of logistic regression can predict the number and structure of students enrolled in higher education.

Low Reynolds number, axisymmetric, isothermal, compressible, slip gas flow in microtubes is investigated in this paper. The problem is solved by the continuum equations, continuity and Navier-Stokes, along with Maxwell first order boundary condition. The analytical results are obtained by perturbation method. The solutions show a good agreement with experimental results.

In this paper, genetic algorithm (GA) based multi-objective optimization technique is presented to search optimum weighting matrix parameters of linear quadratic regulator (LQR). Macpherson strut suspension system is implemented for study. GA is implemented to minimize vibration dose values (VDV), RMS sprung mass acceleration, sprung mass displacement and suspension working space. Constraints are put on RMS sprung mass acceleration, maximum sprung mass acceleration, tyre deflection, unsprung mass displacement and RMS control force. Passive suspension system and LQR control active suspension system are simulated in time domain. Results are compared using class E road and vehicle speed 80 kmph. For step response, GA based LQR control system is having minimum oscillations with good ride comfort. VDV is reduced by 16.54%, 40.79% and 67.34% for Case I, II and III respectively. Same trend is observed for RMS sprung mass acceleration. Pareto-front gives more flexibility to choose optimum solution as per designer's need.

A detailed analysis of the behavior of a commercial magneto-rheological device is presented in the context of woodworking machine tools. This type of device can provide resistive torque to a rotating shaft via a change in fluid viscosity due to a modification in magnetic field, with the resistive torque being proportional to the current passing through an electric winding inside the device. In this way, it is possible to control the transmission of torque by modulating an electrical current. This solution is particularly relevant where highly accuracy torque control is required. At the same time, it is recognized that magneto-rheological devices can introduce a significant delay between activation of the control signal and application of torque. As a consequence, it is necessary to analyze the behavior of the clutch by direct evaluation. Several tests have been performed while increasing the current and experimentally evaluating the applied torque and hysteresis behavior. The presented results demonstrate the need to use software algorithms to fill the time gap between the expected and measured torque and to overcome difficulties related to hysteresis before such a clutch can be implemented for high accuracy applications.

The impact fracture toughness of zeolite reinforced high density polyethylene (HDPE) composites which were prepared by an injection molding has been investigated using essential work of fracture (EWF) concept. The Charpy impact tests were carried out on single-edge-notched bending specimens under velocity of 3.4 m s-1. The results showed that the composites with 5 wt.% zeolite had the highest fracture initiation energy because of the toughening effect of zeolite addition. The composites with zeolite content more than 5 wt.% consumed less energy to initiate fracture than that of pure HDPE. However, the energy for propagated fracture decreased by the presence of zeolite and progressively decreased with increasing the zeolite content in the HDPE matrix. This was due to the addition of zeolite particles restricting shear yielding of the composite matrix resulting in lower energy absorption during short impact testing period.

Glass fiber-reinforced polyester composite (GFRPs) scraps from manufacturing of polyester laminates were pyrolyzed at 500, 550 and 600°C in an 70 Kg innovative batch pilot plant that processes whole parts. The presence of a hydraulic guard guarantees the safety of the process. The influence of the maximum process temperature on yields and chemical-physical properties of pyrolysis products was investigated: the oil fraction was analysed by GC-MS, Viscometer and XRF, while the gas fraction was monitored online during the entire pyrolysis process by µ-GC. Substantial fractions of methane (20.7 vol %) and hydrogen (11.5 vol %) were produced. The solid residue (glass fibers covered by a thin carbonaceous layer) underwent an oxidative process at 500 and 600°C at different residence times to provide clean glass fibers free of organic residues. The effects of both pyrolysis and oxidative step on the glass fibers, obtained in different process conditions, were evaluated by SEM and Raman spectroscopy.

Accurate estimation of friction losses in pipes is an important engineering task. Due to their simplicity, empirical equations are often used for determining pressure drops in pipes. One of the most widely used empirical equations for calculation of pressure drops in straight pipes is Hazen-Williams equation. In this paper, the authors have established a simple method of the inclusion of pipe roughness in Hazen- Williams equation by comparison with a widely accepted Darcy- Weisbach method coupled with Colebrook friction factor formula for developed turbulent flow.

Bird strike events are a potential dangerous problem faced by flight safety nowadays. These events are usually simulated through numerical approaches due mainly to the technical difficulties and high costs associated with experimental tests. The consequences of bird impact can be severe and, therefore, the aircraft components have to be certified for a proven level of bird impact resistance before being put into service. Bird impact poses serious threats to military and civilian aircrafts as they lead to fatal structural damage to critical aircraft components. The exposed aircraft components such as windshields, radomes, leading edges, engine structure, and blades are vulnerable to bird strikes. Among a large number of structural tests an aircraft structure needs a certification requirement for a proven level of impact resistance against bird impacts. Bird strike experiments are very expensive and henceforth explicit numerical modeling techniques have grown importance. Parts of aircraft construction are intensively vulnerable to damage during flight by bird impact. The theoretical approach and results of numerical simulations of dynamic response of the wing loaded by the bird impact are presented. The numerical simulation is carried out using smooth particle hydrodynamics (SPH) method running in the nonlinear explicit finite element code ANSYS AUTODYN. The focus is given to the validation of the stress, strain and deflection of wing on the impact zone. The dependency of given parameters on the variation of ellipsoidal bird aspect ratio, impact velocity and wing design details was discussed. As well, some results of experimental data were given. The behavior of aircraft leading edge against high speed bird impact was successfully simulated and the effect of various parameters on its dynamic response was studied. Numerical model was validated with published experimental results and further employed to investigate the influence of various parameters on dynamic behavior of aircraft leading edge.