جستجوی مقالات مرتبط با کلیدواژه « sensitivity » در نشریات گروه « مکانیک »

Diaphragm pressure sensors are used in various industries. Much research has been done to optimize and improve the quality of these sensors. This paper investigates "sensitivity" as a critical variable in diaphragm pressure sensors based on MEMS technology. Aperture geometry is one of the most influential variables in the sensitivity of a diaphragm sphygmomanometer, which in addition to sensitivity, can affect other variables such as operating range, sensor accuracy, dimensions, and even price. To increase the performance and sensitivity of pressure sensors, the sensor aperture was simulated in AbaqusFEA software, and while validating the computational solver, different geometries were evaluated. The results showed that the circular diaphragm has the best performance. Then the effect of corrugations on the surface of the diaphragm was investigated, and different forms of waves were simulated. The results showed that creating a circular wave with a radius of 15 μm at the end of the diaphragm surface increases the sensor's sensitivity by 18%.

The aerodynamic coefficients of any flying object can be estimated with high accuracy, by aero-ballistic tests, monitored in aerodynamic laboratories. For test-running management, it is necessary to determine the number and type of estimated variables and the station placement of each test. For this purpose, the sensitivity of variables under measurement, in relation to the associated aerodynamic coefficients must be calculated and surveyed. As the trajectory path is a nonlinear equation with six degrees of freedom, in this article we estimate the aerodynamic coefficients and sensitivity of each output to the changes of aerodynamic coefficients using the least square method and fisher data matrix. In other word, if the test data such as the speed and pitch angle are to be measured in an aero-ballistic test, the results of this research can specify their accuracy and sensitivity to each aerodynamic coefficient and the relevant coefficient errors.

Auxetic structures (negative Poisson’s ratio) are a group of materials that expand (contract) under tensile (compression) longitudinal loading. In this work, the effect of re-entrant auxetic structure geometry on Poisson’s ratio was investigated under large tensile loading experimentally and numerically and showed that the location and stiffness of rotation joints are two new important parameters affecting the value of Poisson’s ratio. Poisson's ratio increases as the rotation joints tighten and move away from the center of the structure. Therefore, by changing the location and stiffness of the rotation joints, it will be easy to obtain re-entrant auxetic structures with different Poisson's ratios, which makes it possible to build piezoresistant auxetic sensors with different sensitivities. A highly sensitive, stretchable piezoresistant auxetic sensor made of silicon rubber and chopped carbon fibers is proposed for low strain values. The main feature of this sensor is its high sensitivity for strains less than 6%, which previous works have been unable to detect this range of strains. Shifting strain is the value of strain in which the Poisson's ratio of the structure changes from negative to positive. The provided auxetic sensor performs exceptionally well until the shifting strain and then performs as conventional sensors. This improvement in sensing performance is about 150% (in terms of gauge factor).