Transient high-frequency elasto-acoustic response of a vehicular drivetrain to sudden throttle demand

This paper presents an experimental investigation of the high-frequency structural response of vehicular powertrain systems when subjected to sudden surge in output torque demand as in throttle tip-in from coast to drive condition. The lightly damped drivetrain system has many lash zones represented by low stiffness components and thin shell elements with large modal densities. The high-frequency noise and structural dynamic modes excited under impact conditions through low lash rate zones are of short transitory nature but a major concern to vehicle drivers and other road users alike. An investigation of the root cause of these transitory events requires state-of-the art signal processing techniques at reasonably high sampling rates. This paper presents the results of an investigation into the driveline clonk problem and establishes the relationship between this phenomenon and the low-frequency shuffle of the vehicle

Critical heat flux of nanofluids inside a single microchannel: Experiments and correlations

This study investigated experimentally the CHF phenomena of aqueous-based alumina nanofluids in single microchannels, and assessed the validity of a number of microchannel based CHF correlations using experimental nanofluids data. While usual approaches for CHF enhancement are through the modification of different tube surfaces or employing different inserts, this work showed that CHF in microchannels could be enhanced significantly by the inclusion of small concentrations of nanoparticles. The CHF value was found to increase with increase of mass flux, initial subcooling and alumina nanoparticle concentrations. The maximum subcooled CHF enhancement occurred at the lowest mass flux and highest alumina concentration within the experimental range. In addition, the Lee and Mudawar correlation was modified to predict the critical heat flux of water and nanofluids. The new model was examined by experimental data and 24% and 30% mean absolute error were observed for water and alumina nanofluid respectively

Studying the effect of manager’s Strategic Thinking on Corporate entrepreneurship

The purpose of this research is to explore the effect of managers' strategic thinking on corporate entrepreneurship. To this end, one main hypothesis and five secondary hypotheses were proposed. This study is descriptive-applicable and Lidka studies (1998) were employed to measure managers' strategic thinking and Robins and Kutler's questionnaire (1996) was used to measure corporate entrepreneurship. The statistical population included 118 managers and employees of a manufacturing company in Kermanshah industrial estate. The research sample was equal to 90 using Cochran formula. The results disclosed that managers' strategic thinking has a positive and significant effect on corporate entrepreneurship and all hypotheses were confirme

Seismic vulnerability of air traffic control towers

Airports are one of the critical infrastructures that play an essential role in managing natural disasters through receiving or sending aid and supplies. Air traffic control (ATC) towers are an inseparable part of each airport as the performance of airports depends on the functionality of their ATC towers. Many ATC towers have been designed and constructed based on older versions of modern seismic codes in which seismic design has followed a force-based design approach. This study addresses the seismic vulnerability of three in-service ATC towers which have been designed and constructed according to a force-based design concept. The height of the towers ranges from 24 to 52 m. Fragility curves have been used for the seismic vulnerability study of these towers. For the derivation of seismic fragility curves, 45 earthquake records were selected and classified into low, medium and high classes based on their ratio of peak ground acceleration (PGA) to peak ground velocity (PGV). It was observed that records with a low PGA/PGV ratio imposed the highest level of damage to the towers. However, when towers were subjected to the records with a high PGA/PGV ratio, the damage intensity was not significant. Results indicated that the intensity of seismic-induced damage to the tallest tower was significantly more than that of the shortest tower. It was concluded that only the shortest tower could satisfy the expected seismic performance objectives

Safety Technology Adoption: Predicting Intention to Use Car Dashcams in an Emerging Country

This study investigates the factors that affect the user's intention to use dashcam in Malaysia. This study examines the quantitative relationship of intrinsic as well as extrinsic factors such as personal innovativeness, perceived uniqueness, perceived usefulness, perceived ease of use, attitude, perceived behavioral control, social influence, price value, and trust to the purchase intention of dashcam. Purposive sampling technique was employed to collect responses from 232 respondents based on two criteria: first, individuals who have experienced driving on the road and have a car; and second, individuals who not yet adopt or purchase the dashcam. The data were analyzed using SmartPLS (version 3.3.2). No relationship between personal innovativeness and perceived usefulness was found, in contrast to a significant relationship the former and perceived ease of use. Furthermore, perceived uniqueness was found significant to both perceived usefulness and perceived ease of use. Consistent with the literature, both perceived usefulness and perceived ease of use were identified as factors influencing attitude. However, perceived usefulness did not affect intention. Perceived behavioral control, social influence, attitude, and trust significantly affected the behavioral intention to use the dashcam in Malaysia. This study attempts to integrate and adapt two technology adoption models, namely the Combined Technology Acceptance Model and Theory Planned Behavior and extension of Unified Theory of Acceptance and Use of Technology, also extends the model with personal innovativeness, perceived uniqueness, and trust to fulfil the study's objectives as well

Effect of inadequate lap splice length on the seismic fragility of ground soft-story reinforced concrete frames

In this study, numerical analysis was used to derive seismic fragility curves for 3-, 6- and 9-story reinforced concrete (RC) frame with inadequate lap splice length and ground soft-story condition. The structural models were subjected to 15 far-field natural earthquake records. The peak ground acceleration (PGA) of the selected records was scaled in the range of 0.05g to 0.50g with an increment of 0.05g. Incremental dynamic analysis was employed to determine their inter-story drift demand and capacities. The obtained results indicated that the probability of severe damage to the RC frames increased as the number of stories decreased. It was also observed that the RC frames with inadequate lap splice length exhibited significantly higher probability of collapse when compared with RC frames with adequate lap splice length