Phd Thesis On Mechanical Engineering
(Ph.D.) Mechanical Engineering Courses are to be chosen in consultation with the thesis supervisor. and force through mechanical solutions and During establishing the goals of the Mechanical Engineering PhD How to Design and Defend a PhD Thesis.
Phd Thesis Of Mechanical Engineering
Applications are invited for a PhD student position at University of Montpellier (France), in the NANOMIR group. The group is located at the Electronics and Systems Institute (IES), on the University premises. IES (Electronics and Systems Institute) is a laboratory specialist in reliable electronic systems and components for observation and measurement applications. Thanks to its experience and know-how in the development of systems and components used in sectors such as electronics, microelectronics, photonics, energy, heat and acoustics, IES is able to provide technological and scientific solutions for the observation, measurement and analysis of the physical phenomena surrounding us and thus participate in resolving some of the societal issues encountered at the beginning of the 21st century (energy, water, food, health, urban planning, safety, evolution climate, pollution, etc.).Gas sensors find more and more various applications such as human health, with breath analysis and diagnostic, agro-food monitoring, or air quality qualification. To be efficient, they must exhibit three important qualities: sensitivity, selectivity and stability. A considerable amount of commercial gas sensors are available based on different techniques: electro-chemical sensors, mass sensors and optical sensors. Despite the great diversity of these gas sensors, only sensors based on optical absorption like TDLS (tunable diode laser spectroscopy), can perfectly discriminate the spectral signature of specie among others, thus give a perfect selectivity, combined with a very high sensitivity. However, optical detection sensitivity is strongly related to the used photodetector performances and spectral range. Most optical sensors are large, because the sensitivity is proportional to the optical path and reducing their size is a current research topic.In photo-acoustic spectroscopy the optical detection is replaced by an acoustic detection. A laser, emitting at a wavelength corresponding to an absorption line of a targeted gas specie, is focused into a gas chamber and the measurement is performed by detecting the acoustic pressure generated by the local warming caused by optical absorption. In 2002, Rice University proposed to use a piezoelectric mechanical resonator (a commercial quartz tuning fork QTF) instead of a microphone to amplify the response of the photo-acoustic effect. This new technique was called QEPAS (Quartz-Enhanced Photo Acoustic Spectroscopy). In this case, the laser is focused between the prongs of a QTF. The photo- acoustic effect generates a pressure on the arms of the tuning fork. When the laser is modulated at the resonant frequency of the tuning fork, the active piezo-mechanical mode of the tuning fork is excited, and the response is amplified by the mechanical quality factor of the system. This method avoids using expensive mid-infrared optical detectors with restricted spectral ranges while providing sensitivities down to a few particles per billion in volume, equivalent to those of the best photo-acoustic systems. Photo-acoustic spectroscopy is the best method to achieve both excellent selectivity and sensitivity while being very compact.QEPAS is potentially the best method to achieve selective, sensitive, compact and stable sensors. However, the main limitation of QEPAS systems comes from the use of quartz tuning forks (QTF). These components are cheap and easy to use, but they are not specifically designed for this application. The goal of this PhD thesis is to create a new generation of integrated sensors based on mechanical micro-resonators for high-selectivity and sensitivity gas photo-acoustic detection (sub-ppm concentrations), in a very compact, robust, portable system. Based on photo-acoustic detection, they will offer the possibility to address a wide variety of gas, by simply replacing the exciting laser source.Never has a micro-mechanical resonator been entirely thought and designed for photo-acoustic detection. This PhD thesis aims at studying all physical concepts to optimize the micro-resonator design and improve the sensor sensitivity. Capacitive MEMS transducers offer advantages compared to others pressure sensors, by providing a potential excellent sensitivity with easy measurement. The micro-resonators will be developed in the silicon technology, in order to benefit from its maturity. More specifically, SOI (Silicon On Insulator) based fabrication technique is chosen to fabricate the first micro-resonators. The technological process is then simpler and opens the way to optimized geometries that can improve the sensibility of the sensor. The sensitivity improvement will allow placing the exciting laser next to the micro-resonator, eliminating the need for any optical element used to focalize laser light. Without optical elements, we will be able to realize very compact and robust gas sensors. The sensor composed of the laser sources and micro-mechanical resonator should be 0.5 cm long and 0.25 cm large. It will be the smallest photo-acoustic gas sensors ever realized with such sensitivity and selectivity. These compact and robust detectors will allow the measurement and analysis of atmospheric air on a large variety of sites.The main application is the detection of gaseous species in ambient air, to control environmental composition and emissions. The level of pollutants in the air changes dramatically over time and space. It can vary from sidewalk to sidewalk in a city. It is for these reasons that monitoring air pollution is a difficult and complex problem. By using smaller gas sensors, we can build a large sensor array to track all of the most important air pollutants in real time. They will allow to perform infield measurements with an excellent selectivity and sensitivity of a wide variety of gases. For example, the sensor developed in this project will be able to identify and quantify CO, CO2, NO, NO2, SO2, CH4, ... These gases are already studied in our group on a QEPAS setup. Miniaturized gas sensors based on mechanical micro-resonator offer competitive advantages compared to all existing gas sensors. For example, a portable sensor connected to a smart phone can be used very easily for indoor and outdoor ambient air quality monitoring. Another application example for compact and light gas sensors is the pollution detection in a vast area, one can imagine equipping a small drone with such a system.
QEPAS is potentially the best method to achieve selective, sensitive, compact and stable sensors. However, the main limitation of QEPAS systems comes from the use of quartz tuning forks (QTF). These components are cheap and easy to use, but they are not specifically designed for this application. The goal of this PhD thesis is to create a new generation of integrated sensors based on mechanical micro-resonators for high-selectivity and sensitivity gas photo-acoustic detection (sub-ppm concentrations), in a very compact, robust, portable system. Based on photo-acoustic detection, they will offer the possibility to address a wide variety of gas, by simply replacing the exciting laser source.
Phd Thesis Mechanical Engineering
The sample schedule below lists all courses required to complete a BSE degree in Mechanical Engineering at the University of Michigan. This sample schedule is meant to be a guide only and will likely be different from most students' long-term degree plans.
Phd Thesis In Mechanical Engineering
Prior to joining at NIT Silchar, he worked as a Post-doctoral Fellow for almost one year at Indian Institute of Technology Kharagpur after completion of his PhD from Mechanical Engineering Department of the same Institute.