Sonya T. Smith

Performance Evaluation of Fuzzy Switching Position Controller for Automation and Process Industry Control

This paper presents the development and implementation of a new and practical fuzzy switching position controller for process industry control. Compatible with the structure of a bang-bang controller, a two-input fuzzy switching position controller with five rules is proposed. The idea is based on constructing a fuzzy switching control law which is functionally analogous to a traditional bang-bang controller. Fuzzy logic rules are used to enable an improved version of the conventional bang-bang control. The objective is to replace the conventional bang-bang controller with the proposed fuzzy switching position controller. A modified three-stage bang-bang controller is also designed and implemented. This controller is tested under the same conditions as that of the proposed fuzzy switching position controller, and its performance is used as a basis of comparison by which both controllers are measured. Both controllers are implemented in real time, using the position control of a brushless dc motor drive found in the majority of these new robotic devices. A test bed was built and tested in the laboratory using a collection of tools that include both off-the-shelf hardware (dSPACE DSP DS1104) and software (MATLAB/Simulink). Experimental results show that the fuzzy switching position controller produces adequate control performance, particularly in handling nonlinearities and external disturbances. The efficacy of the fuzzy switching position controller is demonstrated by its positive results, practicality, and feasibility in the process industry sector, when compared with a modified traditional bang-bang controller.

The Howard University Program in Atmospheric Sciences (HUPAS): A Program Exemplifying Diversity and Opportunity

ABSTRACT This paper discusses experiences and lessons learned from developing an interdisciplinary graduate program (IDP) during the last 10 y: The Howard University Graduate Program in Atmospheric Sciences (HUPAS). HUPAS is the first advanced degree program in the atmospheric sciences, or related fields such as meteorology and earth system sciences, instituted at a historically black college or university or minority-serving institution (MSI). The PhD program in atmospheric sciences was implemented in 1996 as a direct result of synergies between overlapping interests in initiating interdisciplinary programs within the Howard University Graduate School, and within a National Aeronautics and Space Administration (NASA)–funded university research center to produce greater institutional depth and breadth of research in the geosciences. The development of HUPAS has revitalized a significant segment of the Howard University research community, leveraged a significant level of funding for research and training, raised the visibility of the university in a vibrant area of research, and made a great impact on the national statistics for the production of underrepresented minority (URM) advanced degree holders in the atmospheric sciences. Though the HUPAS program is still in its infancy with respect to many well-established programs in atmospheric sciences and meteorology, it has benefited from a number of federal, state, and academic partnerships, which have led to increasing capacity development, improved resources for students, and research infrastructure enhancements. Specific examples of successful partnerships among HUPAS and federal funding agencies such as NASA and National Oceanic and Atmospheric Administration have been critical cornerstones in the development process. The student recruitment and retention strategies that have enabled the success of this program and statistics of student graduation during the last decade are discussed. Entering its tenth year, HUPAS has apparently overcome many of the pitfalls that plague the development of IDPs that draw their faculty from existing, traditional departments. It is hoped that the approaches and lessons learned and discussed in this paper may be illuminating and useful for others to emulate in the development of a similar IDP programs in atmospheric and other earth and environmental sciences, especially at MSIs and at institutions with small- to medium-sized graduate enrollments.

A Computational Model of Vestibular Fluid Response to Human Body Rotation

A computational model was developed to study the response of vestibular fluid to body motions, relating eye movement to vestibular displacement. The response in the semicircular canals (SCCs) and otolith organs were approximated as a torsional pendulum and a forced wave equation, respectively. The results of the math model were found to be consistent with results found in previous models. The results of the model will also be compared to those found experimentally using VALUS, a rotational platform updated to be used for vestibular testing.Copyright

Hybrid-MCX-1, BWB and 777 Aircraft Comparison

Conceptual design is the first and most important phase of an aircraft’s configuration and system development process. That being said, there is no denying that innovation in aviation has stunted over the last 50 years; the once every present fascination of flying has been blanketed by the rapid profit-driven commercializing of an industry. Moreover, we have reached an apex of maximizing the efficiency of current passenger aircraft model configurations. In recent times, new research and development has culminated to the introduction of aerodynamic structures to address key issues such as stability and fuel efficiency. This research paper seeks to push the envelope of innovation with a brand new perspective on how we view air travel — redefining the Why, What and How. It explores novel concepts such as Boeing Blended Wing Body (BWB) aircraft shown in, which does not follow the conventional Tube and Wing (TAW) configuration. It is a tailless design that integrates the wing and the fuselage into a single-lifting surface. The most common advantages include a higher lift-to-drag ratio and higher payload capacity due to a distribute load along the centerline of the aircraft. On the other hand, a tailless configuration comes at a cost to in-flight maneuvering and stability.The unique design of the Hybrid-MCX-1 aircraft involves the application of the active aero-elastic tailoring to aircraft topology optimization for both subsonic and transonic regimes. With a focus on experimental wind tunnel testing and high-fidelity simulations, this project proposes a new concept that deviates from today’s tubular and wing concept. The aircraft has a unique shape with a forward fuselage that starts off with the conventional tubular and winged aircraft design currently flown in commercial travel, but deviates to a wider cross section at the center of the fuselage. The model has self-supporting, cantilever, dihedral, swept wings, with pronounced fillets at the junction of the wing root and fuselage, blending them smoothly. This smooth transition reduce interference between airflow over the wing root and the adjacent body surface, ultimately reducing drag.The engines of the Hybrid-MCX-1 are mounted by at 45-degree angle on the rear of the plane. This engine location offers the opportunity for swallowing the boundary layer of air from that portion of the center body upstream of the inlet, providing improved propulsive efficiency by reducing the ram drag. The Hybrid-MCX-1 also possesses a vertical tail that bisects the engines. As with current commercial aircraft, this tail provides lateral stability and controls the yaw. In the case of the BWB, yaw control is made possible by sweeping the wing and downloading the wingtips. However, this approach reduces the effective aerodynamic wingspan of the aircraft and imposes a significant induced drag penalty. The presence of a tail on the concept model addresses the aforementioned issue and rectifies unwanted yawing that may arise during cross wind flight conditions.The rear end of the aircraft decrease significantly in vertical thickness when compared to the lateral thickness to minimize the possibility of flow separation as air passes around the wings and over the front half of the aircraft while maximizing total lifting surface area. The pylons are adequately sized to avoid aerodynamic interference between fuselage, pylon and nacelle but still relatively short to minimize drag.Copyright

Nanofluidics of Mammalian Hearing

The inner hair cell stereocilia bundle performs the role of transducer in mammalian hearing. Acoustic stimuli deflect the hair bundle to open ion channels, resulting in cation influx and the subsequent release of a neurotransmitter at the base of the cell. Hypotheses for this transduction include fluid shear-driven motion between the tectorial membrane and the reticular lamina to deflect the bundle. It is presumed that ‘molecular gates’ sense tension in tip-links that connect adjacent stepped rows of stereocilia to open the channels. However, almost nothing is known about the endolymphatic flow in the micron-sized gap surrounding the bundle and the nanoscale sized gaps between individual stereocilia rows and between individual bundles. Here we show with nanometer resolution, how each row of stereocilia, their associated tip links and gates and the corresponding flow patterns move in response to acoustical input.© 2011 ASME