Efficient whole cell biotransformations, in particular microbial whole cell Baeyer-Villiger oxidation with molecular oxygen, demand comprehension and optimization of the process details involved. Optimal provision of oxygen and control of bioprocess parameters are pivotal for their success. The interrelation of cell density and oxygen supply in an in situ substrate feeding and product removal (SFPR) whole cell Baeyer-Villiger oxidation process was investigated in detail. Both parameters were optimized with respect to practical considerations. The outcome of this study supports a schematic process model, allows estimation of optimum process conditions and exploration of its limits.
The use of fiber optic sensing in the oil and gas industry has greatly expanded over the past two decades. Since the first optical fiber-based pressure sensor was installed in a well in 1993, the industry has sought to use fiber sensing technology to monitor in-well parameters. Through the years, optical fiber sensing has been used in an increasing number of applications as technical advances have opened the door for new measurements. Today, fiber optic sensors are used routinely to measure temperature throughout the wellbore. Optical sensors also provide pressure measurements at key locations within the well. These measurements are used to verify the integrity of the well, provide feedback during well completion operations, including the actuation of downhole valves, and to monitor the production or injection process. Other sensors, such as seismic monitors and flowmeters, use fiber sensing technology to make in-well measurements. Various optical sensing techniques are used to make these measurements, including Bragg grating, Raman scattering, and coherent Rayleigh scattering. These measurements are made in harsh environments, which require rugged designs for optical cable systems and instrumentation systems. Some of these applications have operating temperatures of 572°F (300°C), and other applications can have pressures in excess of 20,000 psi (1,379 bar). This paper provides a historical perspective on the use of fiber optic sensing in the oil and gas industry from industry firsts to current applications.
A Bragg grating based acoustic emission crack detection (AECD) sensor system is developed. The ultimate goal of the sensor system is to provide structural health monitoring of composite structures. Various aspects of the sensor system including the parameters involving the optical filter using a matched fiber Bragg grating have been analyzed. The prototype sensor system was tested using pencil lead break tests and Open-Hole-Tension (OHT) specimens (ASTM D 5766). The fiber Bragg grating sensor was embedded into the composite tension specimen at the mid-plane and outside of the region under strain so as to reduce the effects of unwanted structural strains in the sensor response. Impact tests with the surface mounted sensor system determined the sensitivity of the sensor to the direction of the stress wave. The tests demonstrate the ability of the AECD sensor system to detect a pencil lead break event and actual AE events from a composite specimen both in the near surface and embedded configurations.
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