Dimitris E. Nikitopoulos - US grants

ABSTRACT


Proposal Number: CTS 9977576

Principal Investigator: E. Podlaha

This Major Research Instrumentation (MRI) award supports the acquisition of an Energy-Dispersive X-ray Fluorescence (EDXRF) unit and a Micro Particle Image Velocimeter (mPIV) to assist the continuing microsystems research, development and educational efforts for several departments at Louisiana State University (LSU). The analysis and control of materials processing steps is essential to the development and fabrication of new devices and the development of novel materials. The EDXRF system will provide a currently unavailable method of chemical and thickness analysis to LSU, giving the capability of measuring composition profiles throughout high aspect ratio components. Many of the microsystems presently under development at LSU involve microfluidic devices and processes (e.g. micro-channels, pumps, heat exchangers, flow control devices, bioanalytical instruments, fuel injectors and fluidic actuators for combustor nozzles). Studies of micro-fluidic systems have been, thus far, possible only on the theoretical and simulation level, while experiments have been limited by the scarcity of measurement methods that can provide local information about such devices. The micro Particle Image Velocimeter (mPIV) system will provide the ability to measure local velocity fields and to visualize the flow in micrometer scale fluidic systems. This instrument will enable researchers to study the physics of micro-fluidic flows critical to the design and optimization of micro-fluidic devices that are fabricated at LSU. The systems acquired through this NSF grant together with the synchrotron resource at the J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices at LSU will provide researchers at LSU with the opportunity to play a leading role in the development and evaluation of microsystems for practical applications.

Investigation of Large Coastal Bridge Performance In Hurricane
Environment, CMS proposal 0301696

PI: Cai, Louisiana State University

When a hurricane strikes the coast, the results are often devastating. Even as storm prediction and tracking technologies improve, providing greater warning times, our nation is still becoming ever more susceptible to the effects of hurricanes due to the massive population growth in the south and southeast along the hurricane coast from Texas to Florida to the Carolinas. As backbones of transportation lines, coastal bridges are extremely important in supporting evacuations. In addition to the general wind-
induced problems, long-span large coastal bridges on hurricane evacuation routes face the threats from the combination of hurricane-induced winds, heavy traffic, and their interactions. The objectives of the proposed study are: (1) to study the performance of large coastal bridges under the action of strong winds as well as heavy traffic. This situation happens in a scenario of hurricane evacuation; (2) to investigate the effect of temporary mass dampers in ensuring bridge safety and/or reducing bridge vibration. The temporary mass dampers can conveniently be driven on the bridge when needed and be removed otherwise; and (3) to advance the state-of-the-art of aerodynamic analysis of large bridges under strong winds.

In a typical aerodynamic analysis of long-span bridges, no traffic load is considered by assuming that bridges will be closed to traffic at high wind speeds. Therefore, bridges have been tested in the wind tunnel or analyzed numerically based on the pure bridge section without vehicles on it. However, during a hurricane evacuation, the bridges may be occupied by slowly moving traffic. On one hand, vehicles affect the modal characteristics and section shape of the bridge, which affects the aerodynamic behavior. On the other hand, the same vehicles may act like mass dampers that may help damp out some vibrations. The total effects of the traffic on bridge performance and also bridge vibrations on vehicles are not clear and no studies have been reported. While it is generally assumed (but still controversial) that turbulence helps enhance bridge flutter velocity, the effects of hurricane-induced high turbulence on bridge stability haven't been adequately studied. These issues need to be addressed to ensure the safety of both bridge and vehicles during hurricanes and evacuations. While the developed procedures are intended for general coastal bridges, the Luling Bridge near New Orleans will be used as the primary subject of study. Both wind tunnel testing and numerical simulations will be conducted. The bridge performance will be investigated by arranging different traffic patterns to find the worst case for safety assurance, and find the optimal pattern that may be utilized for hazard mitigation (e.g., closing certain lanes). Another alternative is to develop a movable TMD system that can be driven on the bridges to act as a temporary vibration damper. The research activities and results will be incorporated into the new education curriculum - Hurricane Engineering developed at LSU with the NSF fund.

The proposed study is to address the issue of how large coastal bridges perform in hurricanes under evacuation conditions. The answer is very important since thousands of lives potentially hinge on the decision of when to close the evacuation routes too soon and people may be trapped in coastal areas subject to storm surge, too late and people may be on the bridge under unsafe conditions. The educational activities include high school outreaching, minority students recruiting, and technical information dissemination. These activities will promote minority participation, affect high school students career path, and foster future engineers to develop more systematical strategies in dealing with the most destructive hurricane hazards for years to come. International collaboration with Tongji University, China, will not only utilize the second largest boundary layer wind tunnel facility in the world, but will also foster further research and collaboration, increase the visibility of hurricane engineering in both countries, and combine the resources to deal with the worldwide engineering challenge of the 21st century . mitigating hurricane hazards. To achieve the research objectives, a unique team of researchers is formed. This team consists of Dr. Cai (PI) who has extensive expertise in wind vibration analyses, Dr. Levitan (co-PI), director of the LSU Hurricane Center and an expert in wind loading, Dr. Nikitopoulos (co-PI) is the Director of Wind Tunnel Laboratory with expertise in fluid dynamics and wind tunnel simulation.

A multidisciplinary graduate program of education, research and training in Multi-Scale Computations of Fluid Dynamics (CFD) at Louisiana State University (LSU) will be undertaken in interdisciplinary partnership between the various CFD groups and the Center for Computation and Technology at LSU, and outreach partners at Southern University, Louisiana Tech University, and LSU Eye Center. All schools are tightly connected by a 40 Gbit optical network and tied to the National LambdaRail. The intellectual merit and purpose of this program is to provide doctoral students with enhanced multidisciplinary education and training that will integrate all elements critical in solving critical CFD projects of the future: distributed collaborations connected by optical networks, high performance and grid computing techniques, CFD as a fundamental discipline, and numerous fluid dynamical application areas where Louisiana has unique research strengths. Braoder impacts of the project relate to application areas that span the spectrum of flow scales (from microns to kilometers) and include biological/biomedical flows, estuarine/oceanic flows, reservoir flows, and astrophysical flows. IGERT research and education will occur at the disciplinary interfaces, with faculty mentors from two or more disciplines, and a focus on enabling large-scale parallel computing of flow systems that resolve scales and their dynamics that were previously not possible. IGERT students will complete a program of study that includes an original interdisciplinary research problem for their dissertations, and a mix of interdisciplinary fluid dynamics, computational science and CFD courses that are team-taught and cross-listed across the various departments. IGERT is an NSF-wide program intended to meet the challenges of educating U.S. Ph.D. scientists and engineers with the interdisciplinary background, deep knowledge in a chosen discipline, and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing innovative new models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries.

1067583
Park

The ability to acquire quantitative information on molecular inputs in near real time offers many exciting new opportunities in diverse applications such as basic biology, medicine, forensics, and homeland security. Nanochannel-based technologies have demonstrated potential as a technology in the analysis of biopolymers, but their use is still in its infancy and replete with research challenges. The goal of this proposed work is to develop an innovative nanofluidic biosensor utilizing time-of-flight (ToF)-based transduction of single molecules in a 2D nanochannel for accelerating the acquisition rate of chemical/biochemical information to near real time irrespective of the targets being analyzed. In order to fulfill the promise of this exciting field, multidisciplinary research efforts, aimed at both the engineering and scientific challenges, are imperative. The main scientific innovation is the employment of a new sensing mechanism, namely ToF transduction to identify different molecules (we will use peptides as example targets in this application) the size of which is comparable to the dimensions of the nanochannels. During translocation of a peptide through the nanochannel, its mobility is determined by the ionic state of the molecule as well as the interactions between the molecule and walls of the nanochannel. The ToF for the translocation will provide a signature uniquely specific to the molecule being monitored. The engineering innovation includes low-cost fabrication of multi-scale fluidic platforms consisting of micro- to macroscale fluidic networks and sub-50 nm nanochannels in polymer substrates via direct molding. Use of polymer substrates is predicated by their ability to be produced using replication technologies as well as the availability of polymers with a broad range of surface chemistries, which enables optimization of biomolecule/nanochannel wall interactions to facilitate ToF identification. Using the developed technologies emanating from this application, further innovative discovery efforts will be generated for a broader user community due to the systems? low-cost and simple operation with the ultimate goal being application of these novel biosensors for the real time identification of single monomers to elucidate the primary structure of biopolymers, such as nucleic acids and proteins.

Intellectual Merit: The proposed research will integrate critical studies in fabrication, assembly, biophysical characterization and simulations, to formulate a detailed understanding of the translocation behavior of peptides through nanochannels. Through fundamental studies of the physics of the confined translocation of single peptides, controlling parameters that maximize the discrimination between individual peptides will be identified. Low cost fabrication, enabled by the use of polymers, will be achieved by the use of parallel processes such as nanoimprint lithography in the fabrication of an array of nanochannel sensing platforms over a large area. Completion of the proposed work will demonstrate the feasibility of this ToF-based sensing mechanism and lay the groundwork for the development of low cost fabrication strategies for the nanochannel sensing platforms for broader applications.

Broader Impacts: Education and outreach activities will exploit the revolutionary and multidisciplinary nature of the emerging field of nanochannel-based biosensors to engage K-12, teachers and undergraduate students in science,technology, engineering, and mathematics. To this end, the following activities will be pursued: (1) develop experimental nanotechnology teaching modules; (2) give seminars for secondary education students; (3) initiate undergraduate and graduate students in research; and (4) recruit undergraduate and graduate students from underrepresented groups. These activities will take advantage of the education and outreach infrastructure already in place at LSU and its Center for BioModular Multi-Scale Systems. This infrastructure includes several nationally recognized programs devoted to under-represented students.