Kamran Mohseni - US grants

Proposal Number: 0427947
PI: Kamran Mohseni
Institution: University of Colorado, Boulder
Title: ITR - Loosely Cooperating Micro Air Vehicle Networks for Toxic Plume Characterization

Abstract:

Release of contaminants in urban areas can lead to severe public health consequences. This project develops an integrated Sensor Flock to enable rapid characterization of toxic plumes for contamination prediction and source location. A Sensor Flock consists of semi-autonomous micro air vehicles (MAVs) transporting miniature toxin sensors throughout the atmosphere above populated areas, networked to a base station providing toxin dispersion modeling and flock supervision, using novel lightweight, real-time, data-reactive wireless information routing. MAV platforms lower manufacturing costs, reduce risks of collision damage, and reduce visibility and noise that might create public alarm.

The concept of Information Energy is introduced to tightly integrate advances in three interdisciplinary areas: aerodynamics, networking, and control. This enables high-quality information products from the Sensor Flock, using relatively simple individual vehicles. The MAVs are designed based on biomimetic principles of bat flight to enable exceptional flight performance. Vehicle control is based on a hierarchical information energy formulation, producing simple gradient-descent guidance laws on each vehicle, but with well-understood flock clustering behavior toward regions of high-quality data. The behavior of data-driven routing in each of the following three communication scenarios is investigated: inter-MAV exchange of high-quality data for flock convergence; MAV-to-ground collection of sensor data; and ground-to-MAV command and control.

Existing disciplinary courses at CU Boulder are enriched with results from this work, expanding student multidisciplinary exposure. A summer Aerobotics program enables local high school students to participate in a design/build/fly competition integrating computer science and aerospace engineering.

A novel pulsatile jet propulsion scheme for low speed maneuvering of small underwater robots is developed, demonstrated, and characterized. This propulsion scheme is loosely analogous to that used by squid and jellyfish. The potential for pulsatile jet propulsion is explored by first optimizing the design of a pulsatile jet actuator and associated actuation concepts. Next, a vehicle-level fluid dynamical model is developed in order to capture the interaction of the pulsatile jet flows with the primary flow past the vehicle. Prior development in nonlinear averaging-based vehicle feedback control schemes is adapted to this technology using such models. The pulsatile jet prototypes and control scheme is integrated into a prototype underwater vehicle, whose performance is characterized. The suggested propulsion scheme has very few moving parts, has no protruding components that increase drag, and takes up relatively little volume.

Undergraduate engineering students are heavily involved in the design, fabrication, and testing of the pulsatile jet actuators and underwater vehicle prototypes proposed in this project. These activities provide excellent hands-on engineering experiences for the participating students.

ABSTRACT

Proposal Number: CTS-050004
Principal Investigator: Mohseni, Kamran
Affiliation: University of Colorado-Boulder
Proposal Title: SGER: Electrowetting Actuation of Droplets for Cooling of Integrated Circuits

This award is for a Small Grant for Exploratory Research awarded by the Thermal Transport and Thermal Processing Program of the Division of Chemical and Transport Systems. Heat is an unavoidable byproduct of normal operation of an electronic device. Reduction in circuit delay and therefore an increase in speed are often achieved by higher circuit packaging density accompanied by increased power dissipation per circuit. As a result of more demand for increased packaging density and performance, the required heat flux removal is increasing at a challenging rate. To this end, this Small Grant for Exploratory Research (SGER) is focused on electrical modulation of discrete droplets for actuation and pumping of liquid droplets, in particular metals/alloys, for active thermal management of compact micro systems and heat removal from the hot spots on any solid surface. Preliminary calculations suggest significant heat removal capability by using this technique.

Intellectual Merit: This effort is aimed at providing quantitative data in support of the proposed technique. The proposed technique is based on two observations: (i) By using metals/alloys that are liquid at room temperature (instead of e.g. air cooling) heat transfer rate of a cooling system can be enhanced significantly, (ii) Electrocapillary is an efficient, low power consumption, and low voltage actuation technique for pumping liquids
at micro-scales. Feasibility analysis for such a system will be conducted by focusing on two separate aspects of the project. First, modeling of both electrowetting on dielectric (for conductive liquids) and dielectrophoresis (for dielectric liquids) will be conducted to
find droplet velocity and heat transfer rate for a given actuation voltage. In order to validate these models, experiments will be conducted where the heat transfer coefficients and droplet velocities are directly measured for various actuation parameters.

Broader Impacts: It is expected that this project will create innovative advances in a new class of thermal management techniques for compact micro systems. Existing disciplinary courses at CU Boulder will be enriched with results from this work, expanding student
multidisciplinary exposure to thermofluidics, micro fabrication, and numerical simulation. Advances in thermal management of compact micro systems and micro fluidics are anticipated based on the research proposed in this investigation. These will be disseminated widely at national meetings and through journal publications.

CBET-0756505, Mohseni

Heat is an unavoidable byproduct of the normal operation of an electronic device, generated as a result of electrical energy being converted to thermal energy during circuit activities. As the need for fast electronic devices increases, the ability to safely dissipate large amounts of heat from very small areas is key to many of today's cutting edge technologies. To this end, cooling of electronic systems (such as computers, lasers, radars, etc) is becoming a major challenge in the design of next generation of such devices.

The proposed investigation will explore the active and on-demand micro actuation and transport of liquid droplets, a process dubbed Digitized Heat Transfer (DHT), for effective thermal management of high power compact systems. In DHT, individual droplets are discretely manipulated. This enables the basic operation in any fluidic device (transporting, mixing, and analyzing) to be performed in simple instructions without the need for moving mechanical parts.

In this investigation, the transport of coolant is achieved by modification of surface tension forces on a droplet interface by application of electric forces. Surface tension is a dominant force for liquid handling and actuation at micro scales. The proposed technique is based on three observations: (i) by using metals/alloys that are liquid at room temperature (instead of e.g. water or air) the heat transfer rate of a cooling system can be enhanced significantly, (ii) moving droplets are dominated by an internal recirculation (missing in continuous flows) that will enhance mixing and consequently heat transfer; (iii) electric actuation of a droplet interface is an efficient, low power, and low voltage actuation technique for manipulating liquids at micro scales.

Various electric actuation methods will be investigated by computational and theoretical means. DHT will be studied at a fundamental level by identifying the relevant parameters and non-dimensional numbers, and by determining the heat transfer rate for a periodic array of conductive and dielectric droplets of various sizes. It is expected that digitized electrohydrodynamics will offer a viable cooling strategy to achieve the most important objectives of electronic cooling, i.e. minimization of the maximum substrate temperature, reduction of the substrate temperature gradient, and removal of substrate hot spots.

In addition to the technical advances in thermal sciences, fluid dynamics, and computational techniques anticipated above, this project provides an application focus that will be of interest to researchers and students working in electrical, chemical, mechanical, and aerospace engineering, as well as physicists, biologists, and medical scientists. Undergraduate research assistants will be sought via supplementary REU support, and can be expected to come from the previously mentioned fields. The PI intends to develop a course in micro scale convective transport and expand his current course on micro and nano fluidics with the addition of both a fabrication and a computational component. The PI's existing multidisciplinary courses will be enriched with results from this work, expanding student exposure to different aspects of micro fluidics. Because of the multidisciplinary aspect of this subject, wide student interest is expected. Storytelling will be reinstated in the classroom as a method of not only science education but also ethics education, history, and community values. A Lilliput Summer Camp is also proposed, enabling local secondary school students to participate in a weeklong educational experience with an emphasis micro scale phenomena.

CBET -0854542
Mohseni, Kamran

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

This research program addresses the fundamental science of jet and vortex propulsion by Cephalopods (squid, cuttlefish, etc) and Medusa (Jellyfish) in contrast to more well-investigated aquatic locomotion through body and fin undulations like most fish. We plan a hybrid experimental, computational, and theoretical approach to understand and advance hydrodynamics and biomimicry of aquatic jet propulsion. The research plan has three main thrusts Kinematic Investigation, Computational Fluid Dynamics (CFD) and Experimentation and Biomimicry. A squid care and storage facility will be built for investigation on aquatic thrust-generation mechanism by jet and vortex flow. High-speed photography and flow visualization will provide kinematic data for the squid mantle cavity and siphon during several flow regimes including escape and maneuver. These new simultaneous and detailed measurements are needed for direct numerical simulation of squid locomotion based on the measured kinematic data. In addition, the swimming performances such as swimming velocity, thrust, power requirement and efficiency can be computed directly. The knowledge gained in the kinematic and CFD studies will be translated into engineering design and testing of bio-inspired actuators for effective underwater propulsion. The actuators will be modeled and experimentally characterized. Design of reliable underwater vehicles for sensor networking is playing a major role in National and Homeland Security and costal area protection. Efficient Autonomous Underwater Vehicles (AUVs) are needed for long-term operation in oceans for coastal area monitoring and protection and data collection related to global warming. This project provides an application focus that will be of interest to researchers and students working in ocean engineering, vehicle systems, and biologists. Undergraduate research assistants will be sought via supplementary REU support. The PI intends to develop a course on bio-propulsion while existing disciplinary courses will be enriched with this work, expanding student multidisciplinary exposure. A summer Bio-propulsion Summer Camp for local secondary school students to participate in a week-long educational activity and an International Exchange Student Program, initiated by the PI, will be expanded.

1134229
Mohseni

An objective of modeling of multiscale problems, such as shocks in complex flows, is to derive an evolution equation for large scale quantities without resolving the details of the small scales. This proposal aims at a new technique for deriving fluid equations capable of regularizing discontinuities in the form of shocks without the introduction of viscous dissipation. This is achieved by defining observable fluxes and observable divergence. An observable divergence theorem is then applied to the conservation of mass, momentum, and energy of an inviscid fluid flow. A set of equations, called the observable Euler equations, are derived where they satisfy the conservation laws at the observable scale, alpha. The observable scale is often dictated by our ability to observe a fluid property. This is the resolution scale in numerical simulations or the minimum resolvable scale of an apparatus in an experiment. The classical Euler equations will be recovered if the observable scale approaches zero. This effort is aimed towards theoretical, computational, and physical understanding of the observability and its application to single phase fluid problems with shocks. While the proposed ideas are tested in the context of shock regularization in fluids, this initiative has the potential to be applied to a wide variety of other multi-scale problems such as elasticity, magnetohydrodynamics, multi-phase flows, etc. Reduction in uncertainty of turbulent aero and hydrodynamic predictions will help manufacturers of most related technologies to reduce the cost of their machines and enhance their performances. Considering the role that such problems play in our society, important socio-economical impacts are expected. Undergraduate research assistants will be sought via supplementary REU support, and can be expected to come from these fields. The PI's existing disciplinary courses will be enriched with results from this work, expanding student multidisciplinary exposure. A web site will be developed to disseminate information to the general public.

CBET-1403828
Mohseni


Heat is an unavoidable byproduct of the normal operation of an electronic device, generated as a result of electrical energy being converted to thermal energy during circuit activities. An increase in speed of an electronic system is often achieved by reduction in circuit delay due to higher circuit packaging densities. Unfortunately, this is accompanied by increased power dissipation per circuit. As the need for fast electronic devices increases, the ability to remove heat flux effectively and efficiently is in greater demand. To this end, the ability to safely dissipate large amounts of heat from very small areas is key to many of today's cutting edge technologies. Reducing heat fluxes by an order of 100-1000 W/cm2 and beyond is currently encountered in high performance supercomputers, power electronic devices, electric vehicles, advanced military avionics, radars, and lasers.

The proposed investigation will explore the active and on-demand micro actuation and transport of liquid droplets, a process termed Digitized Heat Transfer (DHT), for effective thermal management of high-power compact systems. The DHT technique has two main advantages. First, the use of individual droplets and the subsequent introduction of recirculation zones inside the droplets allows for an increased heat removal rate as compared to continuous liquid-cooling flows as well as air-cooling systems. Second, the droplets may be discretely manipulated, enabling it individual, instruction-based programming of fluid processing, where droplets are transported, mixed, reacted, stored, and analyzed in packets without the need for moving mechanical parts. This capability of DHT is aptly-suited for transient thermal management and the suppression of temperature overshoots during the dissipation of power spikes.

In addition to the technical advances in thermal sciences, fluid dynamics, and computational techniques anticipated above, undergraduate and graduate students will be trained in these topics. Undergraduate research assistants will be sought via supplementary REU support, and can be expected to come from the previously mentioned fields. The PI intends to develop a course in micro-scale transport at the University of Florida and expand his current course on micro and nano thermofluidics with the addition of both a fabrication and a computational component. The PI's existing multidisciplinary courses will be enriched with results from this work, expanding student exposure to different aspects of micro fluidics.

MRI: Develop Inastrumentation to Advance Fundamental Research on Simulating Complex Wind Flow Near the Earth's Surface


The boundary layer wind tunnel is an essential research tool for creating dynamic wind flow that replicates the natural behavior of wind near the Earth?s surface. This wind flow is applied to models of buildings and other structures to determine their expected performance and to design them to survive extreme wind events. The accurate replication of natural wind in a laboratory is not trivial. The methods and equipment vary depending upon the wind condition (tornadoes, hurricanes, thunderstorms, etc.), and the geographic location of the object being studied (near the coast, in a suburban community, etc.). Current wind tunnel facilities are limited in this regard, each capable of addressing a small subset of wind phenomena. This award supports the development of an instrument that vastly expands the capability of a single facility to study a wide range of wind conditions observed in nature and assess how they affect the built and natural environments. This capability will accelerate the rate of discovery and open pathways to solving problems in the development of resilient infrastructure. Other applications include the study of pollutant dispersion, siting of wind energy resources, biomechanics, human perception of hazards, and micro aerial vehicle development. The project includes participants from five continents. Thus the development of this instrument will strengthen US competitiveness by enabling a breakthrough in boundary layer wind tunnel technology, while enhancing international collaboration on wind hazard issues that impact the entire populated world.

The objective is to develop an instrument capable of simulating nonstationary, non-neutral or transitioning surface flows. Examples include offshore hurricane winds flowing into a terrestrial environment, non-stationary gust fronts in thunderstorms, transient coherent structures induced by the shearing motion aloft and wind-driven rain. The instrument will command static and dynamic control devices that automatically reconfigure to achieve user-specified similarity requirements such as non-monotonic profiles, spatially variable power spectra and integral length scales, transient gusts, and rain entrainment in the flow field. These control devices must work in series (one stage conditions the next) to achieve the intended function of the instrument. The instrument includes components adapted from existing proof-of-concept studies and new technology to be developed. The framework on which the instrument is to be developed is a conventional boundary layer wind tunnel design, as a goal is to create a tool suitable for implementation in facilities worldwide.

The ocean covers about two-thirds of the planet's surface, drives weather, regulates temperature, produces about half of the oxygen in the atmosphere, absorbs most carbons from the atmosphere, and ultimately supports all living organisms on Earth. Furthermore, the ocean has been essential to humans for commerce, transport, food, and sustenance. Nevertheless, 95% of the ocean remains unexplored, and the long term impact of natural or man-made changes on the health of the planet and its occupants are far from understood. This investigation is aimed at addressing some of the challenges in the design and operation of a sustained networked robotic system for monitoring and exploring the vast ocean in cooperation with or in replacement for humans. This project proposes research that will fill the knowledge gap in underwater hybrid robotics, effective navigation and coordination of a team of robots with significant constraints and limited resources, and path planning for a team of robots in harsh mediums and with restricted resources.

The proposed hybrid robotic system takes inspiration from marine animals, with a healthy balance between migratory capabilities and accurate maneuvering in proximity of obstacles. The robot will be outfitted with a distributed pressure and surface velocity sensors to provide total hydrodynamic forces for vehicle control and vortex street identification for obstacle detection. Novel underwater robotic actuators are also proposed and will be employed in the design and operation of a hybrid class of underwater robot with efficient high speed cruising and precise low speed maneuvering capabilities required in many marine applications. These new sensing and actuation capabilities facilitate safe co-operation of robots with humans in the ocean and in proximity of obstacles, humans, and other robots. Availability of such new sensory information and actuation capabilities will also result in a paradigm shift in our approach to vehicle control, path planning, and cooperation. To this end new algorithms will be developed and tested in simulations and experiments in a well-equipped underwater laboratory. The system capability to maximize its contribution as human assistants or replacements in existing and emerging marine applications will be explored.

The design and development of highly-maneuverable aircraft has been a long-standing engineering challenge. This challenge presents itself in almost all flight regimes, from supersonic fighter jets down to low-speed, smaller-scale unmanned aircraft. Despite the very different operating conditions, there is at least one common feature among aircraft designs aiming to provide very agile, yet stable, flight. Namely, the planforms (the shape and layout of an airplane's wing) of such aircraft are of low aspect ratio. Recent studies suggest that the aerodynamic and gust-response of such low aspect ratio fliers are significantly different than larger flyers and not well understood. This issue constitutes a critical gap in aerial vehicle development, and this research project addresses a critical gap in the development of reliable and fully controllable aerial drones. The researchers will also enhance course curricula with results from this research, and a course on unsteady low Reynolds number aerodynamics will be developed. A summer program is proposed that will enable local high school students to learn aerodynamics and flight concepts and to participate in a design/build/operate competition integrating fluid dynamics, aerodynamics, and aircraft design.

This research project takes a fresh look into new features of steady and unsteady aerodynamics of low aspect ratio wings. Recent discoveries of complex aerodynamic flow-structure interactions have been attributed to an inherent coupling of lateral and longitude loadings and these are unique to low aspect ratio flyers. These phenomena are, in turn, related to the vortex-dominated flow generated by such wings. The proposed work is divided into three main research thrusts. (i) The prediction of flow separation, (ii) The connection between unsteady vortex generation of low-aspect-ratio surfaces and the instantaneous loadings, and (iii) Understanding of how key changes to the vortex topology over a wing in cross-flow modify the asymmetric wing loading. Flow field measurements using digital particle image velocimetry and direct force/moment measurements are correlated with the vortex structures in the flow. Some theoretical modeling will also complement the experimental effort. This knowledge may motivate unique flow control or wing morphing strategies during flight in gusty environments.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.