Band 3, Heft 2

This research aims to characterize the nonlinear responses of a 3-layer laminated composite cantilever beam systemsubjected to evenly distributed dynamic excitations, with the employment of the Periodicity Ratio (PR) method. Periodic, quasiperiodic, chaotic behaviors especially the behaviors in between period and quasiperiod of the cantilever beam system are quantitatively described. A periodic-quasiperiodic-chaotic region diagram is developed to be used for identifying the global behaviors of the cantilever beam system with a large range of parameters. The research approach demonstrates that the PR method is effective and powerful in analyzing the complex dynamical characteristics of nonlinear cantilever beam systems, and the approach shows significances for industrial application and further nonlinear research in this area.

In literature, it remains unclear how the friction coefficient of motor vehicle tyres and road surfaces is affected by velocity in vehicles fitted with antilock braking systems (ABS) compared to vehicles without ABS. In this paper, the effects of velocity on the friction coefficient of motor vehicle tyres and a paired road surface were examined. Tests were performed in a vehicle with ABS enabled and then disabled, allowing comparison between the two braking systems to be made. Braking, sufficient to cause skidding, was applied in a production large family sedan on a bitumen road surface. The friction coefficient of the vehicle tyres and bitumen road surface, during the skidding, was determined using a Vericombrake test computer fitted in the vehicle. Tests were conducted at a range of velocities between 32.8 km/h and 83.1 km/h, with the ABS being enabled and disabled. In both series of tests, peak maximum friction coefficient or minimum friction coeficient values were observed at around 40 km/h. With the ABS enabled, the lowest friction coefficient was observed at 41.9 km/h. When the ABS was disabled, the highest friction coefficient was observed at 42.2 km/h. As vehicle velocity was increased from 40 km/h, the friction coefficient of the vehicle tyres and road surface increased gradually when the ABS was enabled and decreased gradually when the ABS was disabled. Both series of tests showed evidence of plateau above 60 km/h. The vehicle with ABS enabled showed a decrease in the friction coefficient between 60 km/h and 80 km/h. The results suggest that a second peak may be observed around 70 km/h to 80 km/h or alternatively an ongoing plateau may occur. The friction coefficient of motor vehicle tyres and paired road surfaces is affected by velocity with both braking systems. The nature of the effect is dependent upon whether ABS is fitted and working.

While the conventional and non-conventional oil reserves are growing as growing is the oil production, the growing reserves of natural gas and the huge coal reserves make attractive the production of synthetic transportation fuels having properties similar to gasoline, diesel or jet fuels from the coal or gas feed stock. The paper discusses production and reserves of oil, gas and coal and their potentials as a source of power, heat and fuels for at least a century from now. In addition to the Fischer- Tropsch suite of chemical reactions, methanol synthesis and other paths are worth consideration to produce fuels from coal and natural gas. The integration of the fuel production with power generation and waste heat recovery and the valorization of by-products are key factors for better economic, environmental and energy costs.

This article presents the results of the study of two energy harvesting systems (EHS). One is constituted of a ferromagnetic mass put between two opposite electromagnets, while the other is constituted of a self-excited oscillator. The dynamical behaviour of both systems presents bursting oscillations. The characterization of EHS is also made, where the generated power is calculated in terms of mechanical load characteristics as well as in terms of the electric load.

Even if sea levels fluctuate with decadal and multi decadal periodicities about a linear trend without any positive acceleration component, many papers continue to compare different compilations of tide gauges of different length and different locations or assemble selected tide gauges of selected length and location to prove that sea levels are accelerating in Australia and elsewhere in the world when they are not. It is proposed here a novel procedure fitting the tide gauge data with linear and multiple sinus functions that also iteratively completes the gaps in the recorded data with subsequent guess of the fitted function. It is shown that the tide gauges of Sydney and Fremantle, the only two exceeding a century in Australia, are acceleration free and naturally oscillating with different periodicities, phases and amplitudes for the Indian and Pacific Ocean locations. It is also shown that tide gauge records of length smaller than 60 years have rates of rise differing considerably from the legitimate long term trends, and these values may change significantly from an update to the other because of the natural oscillations. It is definitively assessed that tide gauge records of length about 20 years, with a starting point at the time of a valley of one peak and valley multi decadal oscillation for the specific of the most part of the coastline of Australia, return completely unrealistic values for the rate of rise of sea levels. The only reliable assessment of sea level trends along the coastline of Australia continues to be the determination of the rate of rise by linear fitting of all the available data in all the available station, providing the total numbers of years recorded exceed at least 25 years to make the population significant, as historically done by theNational Tide Centre of theAustralian Bureau of Meteorology prior of the censored 2009 survey. While some changes are expected in the individual values of the rate of rise fromone of these surveys to the other, and the introduction of new stations satisfying the 25 years requirement could also affect the average tide gauge result, these sea level surveys conducted without cherry picking the station and the time window generally provide about same average sea level rates of rise survey after survey.

In this investigation, the steady boundary layer flow of Williamson fluid is studied. The nonlinear partial differential equations are transformed into ordinary differential equations by using similarity transformations, then the series solution are obtained by employing homotopy analysis method (HAM), in the four flow problems of a Williamson fluid namely Blasius, Sakiadis, stretching and stagnation point flows. The influence ofWeissenberg number on the velocity and skin friction coeffcient is analyzed through graphical and tabular results.

The aim of this paper is to propose an efficient numerical method for solving the integro-differential equations arising in many braches of sciences using Bernstein polynomials. This algorithm based on Bernstein polynomials approximation for integro-differential equations. First, Bernstein operational matrix of differentiation is derived using Bernstein polynomials and then applied to solve integro-differential equations. The solutions obtained by proposed method indicate that the approach is easy to implement and computationally very attractive. A good agreement between the obtained solution and some well-known results has been obtained. Two numerical examples are provided to show the advantage of using Bernstein operational matrix. This method is capable of greatly reducing the size of calculations while still maintaining high accuracy of the numerical solution.