Engineering

A computed model for tribological properties of porous self-lubricating PPS composites: Numerical analysis and experimental verification
A novel 2D model that was based on the cross-section microstructure of porous PPS composites was established to predict its tribological properties. The variable λ, based on pore size and spacing, was used in the micro-scale model. Heat-stress coupled field analysis was applied to study the self-lubricating behavior and the effects of porosity on the tribological properties of porous PPS compo...


Stress corrosion failure of an X52 grade gas pipeline
In the present work, the failure investigation of a 45.72cm (18in.) diameter gas transmission pipeline (X-52 grade steel) has been described. The pipeline was shielded metal arc welded (SMAW) construction, and was welded in the form of spiral. The protective coating, applied on the pipeline, was made of glass fiber reinforced coal–tar enamel. The initial investigation showed that the failure ...
Perforation of aluminium alloy thin plates
Low velocity perforation of aeronautical aluminium alloy sheets 2024 T3 is studied in this paper. After a literature review on recent experiments and models of plate’s perforation, experimental results for 2 thicknesses (2 mm and 4 mm) of plates are presented. Perforation tests are performed with an instrumented drop test. The striker has a large diameter and a conical shape nose. Two models ...


Investigation on high-velocity impact of micron particles using material point method
Continuous high-velocity impact of micro space debris and micro-meteroids may cause significant accumulative damages to spacecrafts. The process of high-velocity impact of micron aluminum particles on the aluminum target is investigated with the material point method (MPM). As a meshfree particle method, MPM is very suitable for solving high-velocity impact problems owing to its prominent advan...
Damage at high strain rates in semi-crystalline polymers
A specific damage characterization method using Digital Image Correlation for semi-crystalline polymers is proposed for a wide range of strain rates. This damage measurement is an extension of the SE E ˙ method [16] which was developed to characterize the behavior laws at constant strain rates of polymeric materials. This procedure is compared to the well-known damage characterization by ...


Analytical and experimental studies on ballistic impact behavior of carbon nanotube dispersed resin
An analytical formulation is presented for the prediction of ballistic impact behavior of multi-walled carbon nanotube (MWCNT) dispersed epoxy resin. The formulation is based on stress wave propagation and energy balance between the projectile and the target. During the ballistic impact event, the energy lost by the projectile is absorbed by the target through various damage and energy absorbin...
Experimental and numerical analysis of the dynamic fragmentation in a SiC ceramic under impact
Silicon carbide ceramics are generally used in armour configurations for the foot-soldier or military vehicles. However, their behaviour during impact is not fully understood. In this work, the dynamic fragmentation of silicon carbide has been characterised through different impact configurations: Edge-On Impact tests and Normal Impact tests have been conducted in open and sarcophagus configura...

Experimental and numerical study of threaded steel fasteners under combined tension and shear at elevated loading rates
The behaviour of threaded steel fasteners subjected to combined tension and shear loading was investigated experimentally and numerically at elevated loading rates. Tests at low loading rates were performed in a servo-hydraulic testing machine, while tests at high loading rates were obtained using a split-Hopkinson tension bar. All tests were carried out using purpose-made fixtures to ensure un...
A residual-based ADF test for stationary cointegration in I(2) settings
We propose a residual-based augmented Dickey-Fuller (ADF) test statistic that allows for detection of stationary cointegration within a system that may contain both I ( 2 ) and I ( 1 ) observables. The test is also consistent under the alternative of multicointegration, where first differences of the I ( 2 ) observables enter the cointegrating relationships. We find the null limitin...

Estimating a spatial autoregressive model with an endogenous spatial weight matrix
The spatial autoregressive (SAR) model is a standard tool for analyzing data with spatial correlation. Conventional estimation methods rely on the key assumption that the spatial weight matrix is strictly exogenous, which would likely be violated in some empirical applications where spatial weights are determined by economic factors. This paper presents model specification and estimation of the...
The Detection and Characterization of Extrasolar Planets
We have now confirmed the existence of > 1800 planets orbiting stars other thanthe Sun; known as extrasolar planets or exoplanets. The different methods for detectingsuch planets are sensitive to different regions of parameter space, and so, we are discoveringa wide diversity of exoplanets and exoplanetary systems. Characterizing such planets isdifficult, but we are starting to be able t...

Impact of contemporary ship stability regulations on safety of shallow-draught inland container vessels
Directive 2006/87/EC of the European Parliament and the Council represents a milestone in the on-going process of harmonization of technical standards for inland vessels in Europe. The Directive prescribes various safety requirements for freight and passenger vessels operating on the European inland waterways. This paper focuses on ship stability regulations laid out in the Directive 2006/87/EC...
Investigating technology teachers’ self-efficacy on assessment
This study explores possible differences in the views on assessment between two groups of teachers teaching technology in compulsory school: (1) teachers with subject-specific teacher training in technology education; and teachers without such training. This topic is of particular interest because of the recent changes in the regulations that govern compulsory schools in Sweden, such that only ...
Blind source mobile device identification based on recorded call
Mel-frequency cepstrum coefficients (MFCCs) extracted from speech recordings has been proven to be the most effective feature set to capture the frequency spectra produced by a recording device. This paper claims that audio evidence such as a recorded call contains intrinsic artifacts at both transmitting and receiving ends. These artifacts allow recognition of the source mobile device on the o...
A new SVM-based active feedback scheme for image retrieval
Relevance feedback has emerged as a powerful tool to boost the retrieval performance in content-based image retrieval (CBIR). Support vector machine (SVM) active learning is one popular and successful technique for relevance feedback in CBIR. Despite the success, for conventional SVM active learning, the users are usually not so patience to label a large number of training instances in the rele...