A method to take account of inhomogeneity in mechanical component reliability calculations

YesThis paper proposes a method by which material inhomogeneity may be taken into account in a reliability calculation. The method employs Monte-Carlo simulation; and introduces a material strength index, and a standard deviation of material strength to model the variation in the strength of a component throughout its volume. The method is compared to conventional load-strength interference theory. The results are identical for the case of homogeneous material, but reliability is shown to reduce for the same load as the component volume increases. The case of a tensile bar is used to explore the variation of reliability with component volume

The Strengthened BTWC Protocol: Implications for the Biotechnology and Pharmaceutical Industry

Ye

Article X: Specific Measures to Achieve Implementation

Ye

A study of commercial vehicle brake judder transmission using multi-body dynamic analysis

YesBraking-induced forced vibration, known as brake judder in road vehicles, causes dissatisfaction to drivers and passengers and also damage and possible early failure in components and systems. In this paper, the transmission of judder vibration from the point of generation (the brake friction pair) through the vehicle structure to the driver is investigated for the particular case of a heavy commercial vehicle. The investigation uses a computer simulation multi-body dynamic model based on the automatic dynamic analysis of mechanical systems software to identify any characteristics of the vehicle suspension design that might influence the vibration transmission from the wheel to the driver. The model uses a simplified rigid chassis and cab to lump the chassis parameters, so that the investigation can focus on the front axle/suspension design, which is a beam axle leaf spring arrangement, and the rear axle/suspension assembly, which is a tandem axle bogie design. Results from the modelling indicate that brake judder vibration is transmitted to the chassis of the vehicle through a leaf spring `wind-up¿ mode and a `walking¿ mode associated with the rear tandem axle. Of particular interest is the longitudinal vibration transmitted through the chassis, since this creates a direct vibration transmission path to the cab and driver. The simulation results were compared with the previously published experimental work on the same design of commercial vehicle, and agreement between the predicted and the measured vibration characteristics and frequencies was found. It is concluded that the rear suspension design parameters could affect the transmission of brake judder vibration to the cab and driver and that a tandem rear axle offers some design opportunity to control the transmission of brake judder vibrations from the wheel to the cab and driver. Given that brake judder has so far defied all attempts to eliminate completely from vehicle brake systems, this is potentially an important opportunity

Mapping Child Well-Being in Duval County, FL

Analyzes the distribution of neighborhood, education, and health/environmental opportunity; impact on health and education outcomes; demographics of those in Children's Commission programs; and marginalized neighborhoods' conditions. Outlines strategies

Modelling commercial vehicle handling and rolling stability

YesThis paper presents a multi-degrees-of-freedom non-linear multibody dynamic model of a three-axle heavy commercial vehicle tractor unit, comprising a subchassis, front and rear leaf spring suspensions, steering system, and ten wheels/tyres, with a semi-trailer comprising two axles and eight wheels/tyres. The investigation is mainly concerned with the rollover stability of the articulated vehicle. The models incorporate all sources of compliance, stiffness, and damping, all with non-linear characteristics, and are constructed and simulated using automatic dynamic analysis of mechanical systems formulation. A constant radius turn test and a single lane change test (according to the ISO Standard) are simulated. The constant radius turn test shows the understeer behaviour of the vehicle, and the single lane change manoeuvre was conducted to show the transient behaviour of the vehicle. Non-stable roll and yaw behaviour of the vehicle is predicted at test speeds .90 km/h. Rollover stability of the vehicle is also investigated using a constant radius turn test with increasing speed. The articulated laden vehicle model predicted increased understeer behaviour, due to higher load acting on the wheels of the middle and rear axles of the tractor and the influence of the semi-trailer, as shown by the reduced yaw rate and the steering angle variation during the constant radius turn. The rollover test predicted a critical lateral acceleration value where complete rollover occurs. Unstable behaviour of the articulated vehicle is also predicted in the single lane change manoeuvre

The Strengthened BTWC Protocol: An Integrated Regime

Ye

Rhythm Class Perception by Expert Phoneticians

This paper contributes to the recent debate in linguistic-phonetic rhythm research dominated by the idea of a perceptual dichotomy involving “syllable-timed” and “stress-timed” rhythm classes. Some previous studies have shown that it is difficult both to find reliable acoustic correlates of these classes and also to obtain reliable perceptual data for their support. In an experiment, we asked 12 British English phoneticians to classify the rhythm class of 36 samples spoken by 24 talkers in six dialects of British English. Expert listeners’ perception was shown to be guided by two factors: (1) the assumed rhythm class affiliation of a particular dialect and (2) one acoustic cue related to the prosodic hierarchy, namely the degree of accentual lengthening. We argue that the rhythm class hypothesis has reached its limits in informing empirical enquiry into linguistic rhythm, and new research avenues are needed to understand this multi-layered phenomenon

The emerging protocol: A quantified evaluation of the regime

Ye