apart from regular wheel wear such as decreasing wheel diameters and reduced flange thicknesses and heights, wheel flats (wf) and oval wheels (or oor, out-of-roundness) are the most common wheelset problems for railway vehicles. within the fp7 research project “saferail”, apt has developed an innovative wheelset monitoring system so-called “wheel flat and out of roundness monitoring (worm) syst...

let g be a (p, q) graph. let k be an integer with 2 ≤ k ≤ p and f from v (g) to the set {1, 2, . . . , k} be a map. for each edge uv, assign the label |f(u) − f(v)|. the function f is called a k-difference cordial labeling of g if |νf (i) − vf (j)| ≤ 1 and |ef (0) − ef (1)| ≤ 1 where vf (x) denotes the number of vertices labelled with x (x ∈ {1, 2 . . . , k}), ef (1) and ef (0) respectively den...

Wheel/rail contact simulation is one of the most complicated problems in the modeling of railway vehicles. The wheel/rail interaction plays a unique role in rail vehicle dynamics. In this paper, the dynamic response of the wheel on irregular rail track is analyzed with analytical approach using the method of Multiple Scales (MMS). The Hertzian contact theory is used to obtain the relationshi...

This paper presents a comprehensive wheel model that can quantitatively evaluate traction performance of flexible/rigid wheels driving on deformable terrain. The proposed model exploits a terramechanics-based approach with taking account of pressures generated by wheel elasticity as well as terrain stiffness. Deflection of a flexible wheel typically depends on a relative pressure between the wh...

Many scholars have argued that deliberate birth spacing may have played a role before and during the modern fertility transition. There are good historical and theoretical reasons for this view, but it has proved to be hard to demonstrate convincingly that birth intervals were in fact partly determined by attempts at deliberate fertility control. This paper suggests a method of securing evidenc...

We propose a mean-field method to calculate approximately the spacing distribution functions p((n))(s) in one-dimensional classical many-particle systems. We compare our method with two other commonly used methods, the independent interval approximation and the extended Wigner surmise. In our mean-field approach, p((n))(s) is calculated from a set of Langevin equations, which are decoupled by u...

OBJECTIVES This paper examines the effect of household crowding on inter-pregnancy spacing and its association with socioeconomic indicators, among parous mothers delivered in an urban environment. DESIGN Cross sectional survey. METHODS Sociodemographic data were obtained on 2466 parous women delivering at eight hospitals in Greater Beirut over a one year period. Statistical methodology com...

Wheel contour extraction from image is an important unit of any vision-based traffic accident analysis system, and automatically doing it is still a difficult task due to various distracting factors such as low contrast between the wheel and the ground, different wheel types and various weather conditions etc. In this work, a new automatic wheel extraction method is proposed, in which rather th...

Wheel out-of-roundness (OOR) inevitably jeopardizes the safety of railway operations. Regular visual inspection and checking by experienced workers are the commonly adopted practices to identify wheel defects. However, the defects may not be spotted in time. The paper puts forward a new method to real-time monitor wheel OOR based on PVDF strain sensor. Track strain response upon wheel-rail inte...