Current Issue : January - March Volume : 2019 Issue Number : 1 Articles : 5 Articles
Mechanical sensors provide core keys for high-end research in quantitative understanding\nof fundamental phenomena and practical applications such as the force or pressure sensor,\naccelerometer and gyroscope. In particular, in situ sensitive and reliable detection is essential for\nmeasurements of the mechanical vibration and displacement forces in inertial sensors or seismometers.\nHowever, enhancing sensitivity, reducing response time and equipping sensors with a measurement\ncapability of bidirectional mechanical perturbations remains challenging. Here, we demonstrate the\nbuckling cantilever-based non-linear dynamic mechanical sensor which addresses intrinsic limitations\nassociated with high sensitivity, reliability and durability. The cantilever is attached on to a high-Q\ntuning fork and initially buckled by being pressed against a solid surface while a flexural stress\nis applied. Then, buckling instability occurs near the bifurcation region due to lateral movement,\nwhich allows high-sensitive detection of the lateral and perpendicular surface acoustic waves with\nbandwidth-limited temporal response of less than 1 ms....
This paper reports the design, simulation and experimental study of a linear magnetic\nmicroactuator for portable electronic equipment and microsatellite high resolution remote sensing\ntechnology. The linear magnetic microactuator consists of a planar microcoil, a supporter and a\nmicrospring. Its bistable mechanism can be kept without current by external permanent magnetic\nforce, and can be switched by the bidirectional electromagnetic force. The linearization and threshold\nof the bistable mechanism was optimized by topology structure design of the microspring. The linear\nmicroactuator was then fabricated based on non-silicon technology and the prototype was tested.\nThe testing results indicated that the bistable mechanism was realized with a fast response of 0.96 ms,\nwhich verified the simulation and analysis....
This paper assessed the dynamics in the land use/land cover (LULC) within\npatterns of the land use/land cover (LULC) in Calabar metropolis. The thermal\nimageries for 2002, 2006, 2008, 2010, 2012, 2014 and 2016 were obtained\nand processed using remote sensing and Arc GIS software package in order to\ndetermine the changes that have occurred in the LULC in study area. The result\nof the LULC thematic maps overall accuracies was computed above 80\npercent, which indicates an almost perfect agreement. The findings of this\nstudy reveal that, LULC classes by the year 2016 have assumed different dimensions\nof change from the sizes of their previous sizes in comparison to\ntheir current sizes. Land-use pattern changes in the study area were characterized\nby an increase in the built up class, waterbody (though with a slightly\nnegative change from 2010 to 2012) and a predominant negative trend in\ndense vegetation and bare land classes; thus, indicating that the future changing\ntrends will pose a depleting threat to the overall LULC. This study has shown\nthat, the changing land use pattern of the area is capable affecting certain characteristics\nof the environment such as surface temperature. The study recommends\nthat effort should be made by the government to increase urban\nvegetation around city centers and outliers by embarking on reforestation....
In a plating process, the steel plate is conveyed 20â??50 m in the vertical direction for drying,\nduring which it is negligibly supported by rollers and other mechanisms. This produces plating\nwithout uniformity owing to the generation of vibration and other factors, which prevent the increase\nin productivity. We have developed a noncontact guide system for a high-speed traveling elastic steel\nplate in which electromagnetic forces are applied by actuators at the edges of the plate to control the\nplateâ??s position. In this study, we investigated the vibration phenomenon when changing the steady\ncurrent value of the electromagnet used for controlling the position. In addition, we conducted mode\nanalysis of the steel plate to enable stable control even at low steady current values and verified\nwhether stable guide can be provided by using it together with a permanent magnet. As a result,\nby arranging the permanent magnets, stable guidance was possible even at a low steady current\nvalue. In addition, it became clear that vibration damping performance is also improved....
An axisymmetric synthetic jet actuator based on a loudspeaker and five types of flanged\nnozzles were experimentally tested and compared. The first (reference) type of nozzle was a common\nsharp-edged circular hole. The second type had a rounded lip on the inside. The third nozzle type was\nassembled from these two types of nozzlesâ??it had a rounded lip on the inside and straight section\non the outside. The fourth nozzle was assembled using orifice plates such that the rounded lips were\nat both inner and outer nozzle ends. The last nozzle was equipped with an auxiliary nozzle plate\nplaced at a small distance downstream of the main nozzle. The actuators with particular nozzles were\ntested by direct measurement of the synthetic jet (SJ) time-mean thrust using precision scales. Velocity\nprofiles at the actuator nozzle exit were measured by a hot-wire anemometer. Experiments were\nperformed at eight power levels and at the actuator resonance frequency. The highest momentum\nflux was achieved by the nozzle equipped with an auxiliary nozzle plate. Namely, an enhancement\nwas approximately 31% in comparison with an effect of the reference nozzle at the same input\npower. Furthermore, based on the cavity pressure and the experimental velocity profiles, parameters\nfor a lumped element model (mass of moving fluid and pressure loss coefficient) were evaluated.\nThese values were studied as functions of the dimensionless stroke length....
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