About 48 hours after a live lecture, most lectures are archived. Individuals who are unable to attend the lecture or view the live webcast may have the opportunity view the lecture on the TCE’s Video Archive.
Please Note: We only archive a lecture if the speaker has given us permission to do so.
Sensor Placement For Municipal Water Networks
Dr. Cynthia Phillips
Monday, March 27, 2017
We consider the problem of placing a limited number of sensors in a municipal water distribution network to minimize the expected impact over a given suite of contamination incidents. In its simplest form, the sensor placement problem is a p-median problem (essentially a simplified facility placement problem) that has structure extremely amenable to exact and heuristic solution methods. As the models become more realistic, the optimization problems become more complex. Yet many more complex forms can still be transformed to exploit the simplified, tractable p-median formulation.
We will describe research from a long-term collaboration with the US Environmental Protection Agency that began in 2003, covering some work through 2014. Specifically, we will consider the following topics in varying degrees of detail: objective function considerations, handling sensor failures which makes the problem nonlinear, and special considerations to compute practical solutions on low-memory PCs. We will give some (not particularly new) computational results on real data. Time-permitting, we will discuss lessons learned (technical and otherwise) from the 2006 “Battle of the Water Sensor Networks” competition and describe how this long-term research began with an idea, some risks, and some luck.
Many of these algorithms are incorporated into the TEVA-SPOT toolkit, a software suite that the US Environmental Protection Agency has used and is using to design contamination-warning systems for US municipal water systems.
This is joint work with many colleagues at the EPA and at Sandia National Laboratories, covering material reported in over 20 papers in water systems journals and conferences. Some of this work lead to our Edelman-Award-finalist submission: “U.S. Environmental Protection Agency uses operations research to reduce drinking water contamination risks.”
Fog, Feathers and Fluid Friction Reduction using Omniphobic Surfaces: Biomimetic Inspiration and Engineering Realization
Dr. Gareth H. McKinley
Monday, March 20, 2017
A plethora of microstructured surfaces with a wide range of surface chemistries and topographies have been investigated for controlling the wetting (or non-wetting) properties of a fluid/solid interface. Experimental advances in nanofabrication have led to the ability to achieve unprecedented control over the micro- and nano-texture of a substrate and this can result in almost perfect superhydrophobicity. Outstanding challenges include scalability, robustness, and super-oleophobicity; i.e. resistance to wetting by low interfacial tension liquids such as oils and hydrocarbons. Fluorinated silsesquioxanes are nanometer-scale caged molecules that can be heavily fluorinated and molecularly dispersed in a range of polymers to systematically control both the hydrophobicity and oleophobicity (oil-repellency) of substrates. Microtextured re-entrant structures coated with FluoroPOSS are the most oleophobic surfaces produced to date, with alkane contact angles greater than 160˚ and low wetting hysteresis. We have also developed single-step dip-coating and spray-coating processes for applying such omniphobic coatings to a wide-range of substrates. We use dip-coated feathers as natural microstructured and re-entrant structures to illustrate the systematic changes in thermodynamic stability against wetting by water and oil that can be achieved through nanodispersed surface chemical treatments. Real-world applications of these multiscale structured coatings include fabrics with enhanced solvent/oil resistance, efficient separation processes for oil/water dispersions, reduction of ice- and gas hydrate adhesion in deep-sea oil/gas exploration as well as ‘fog-harvesting surfaces’ that greatly enhance our ability to collect solar-desalinated water from wind-borne fog, and ‘spray-on’ coatings for reducing frictional drag through modification of the no-slip boundary condition. We demonstrate drag reduction on these surfaces of up to 20%, corresponding to effective slip lengths of approximately 20 µm, at Reynolds numbers Re ≤ 80,000. By using active replenishment of the air layer we can increase this drag reduction to greater than 80% friction reduction.
Curvature Driven Assembly in Soft Matter
Dr. Kathleen Stebe
Monday, March 6, 2017
Directed assembly is a major tool in materials science. Particles in suspension form structures in response to external fields. The structures can have interesting properties, ranging from electromagnetic responses to mechanical responses. We have been developing new ways to direct assembly in which we exploit confined soft matter to develop energy fields related to the geometry of the confinement.
When a colloid is placed in soft matter, it deforms its host. If the host is a fluid interface, changes in interface area have an energetic consequence. If the host is a liquid crystal, energies from deforming the director field play this role. If the host is a lipid bilayer membrane, costs associated with bending and tension emerge. In each example, by molding the host, we can define global energy fields that drive the colloid along well defined paths to sites for preferred assembly.
We demonstrate this concept in experiment at fluid interfaces by molding their curvatures. Colloids on this interface have excess energy that depends strongly on the local curvature field. Particles move along well defined paths that correspond to principle axes. We extend the concept by confining nematic liquid crystals (NLC) to mold their director fields. In particular, we study colloids in NLC in grooves and near wavy walls. These platforms provide rich landscapes to mold complex assemblies, to study lock and key interactions, and to study multi-stable states. Analogies to electrostatic multipoles interacting with external fields are discussed, and strategies to drive colloids into complex structures are developed.
The Wireless World: 50 Cell Phones Sold Per Second!
Dr. Zoya Popovic
Wednesday, March 1, 2017
Many of us just turn on our cell phones to find out where we are or what we are doing next. The information gets to us through radio waves, much like it did a century ago in maritime navigation that could have saved the Titanic had someone been listening. Wireless communications, sensing and powering deeply penetrate our lives.
This talk will attempt to answer the questions of where we are now in terms of wireless technology and its applications, how we got there, what are the current challenges, how engineers are solving them, and to speculate a bit on what the future holds. The effects of wireless on the economy are impressive: only in the first quarter of 2015, the iPhone brought Apple over $50 billion, and this is just a part of wireless technology. In recent years, wireless communications accounts for 2% of energy usage in the world, which is equivalent to the aviation industry.
At the University of Colorado, Boulder, our research solves challenges such as how to send more data while using less power, how radio waves can help in medicine, how to make smaller more functional radar, and how to cook smartly
Exploiting Additively Manufactured Microchannels for Cooling
Dr. Karen Thole
Monday, January 30, 2017
Recent technological advances in the field of additive manufacturing, particularly with direct metal laser sintering, have opened up the design space for many heat exchange applications. Additive manufacturing allows for increasingly small, complex geometries to be fabricated with little increase in time or cost. Microchannels are commonly used for cooling electronic equipment as well as gas turbine components, but manufacturing of complex shapes can be an issue. As progress continues, additive manufacturing is one avenue for manufacturing such microchannels; however, the inherent roughness that occurs through the additive process significantly influences the pressure losses as well as heat transfer.
This presentation shows resulting pressure drop and heat transfer measurements of flow through as produced microchannels that have been manufactured using direct metal laser sintering in an effort to better understand resulting roughness effects. Results presented also show the various effects of build direction and channel shape for additive manufactured channels relative to conventional smooth and engineered ribbed channels. Results showed significant augmentation of both pressure loss and heat transfer for the additively manufactured microchannels.
Mesoscale Science: Science Frontier AND Technology Opportunity
Dr. John Sarrao
Monday, January 23, 2017
Mesoscale science embraces the regime where atomic granularity and quantization of energy yield to continuous matter and energy, collective behavior reaches its full potential, defects, fluctuations and statistical variation emerge, interacting degrees of freedom create new phenomena, and homogeneous behavior gives way to heterogeneous structure and dynamics.1 Mesoscale science builds on the foundation of nanoscale knowledge and tools that the community has developed over the last decade and continues to develop. Mesoscale phenomena offer a new scientific opportunity: designing architectures and interactions among nanoscale units to create new macroscopic behavior and functionality.
At a mission-centric laboratory like Los Alamos National Laboratory, the mesoscale also presents an opportunity for addressing decadal challenges in materials performance, especially in extreme environments, through a focus on predicting and controlling materials microstructure at the mesoscale. Los Alamos is championing MaRIE (for Matter-Radiation Interactions in Extremes) as an international user facility to enable unprecedented in-situ, transient measurements of “real” mesoscale materials. Concurrent advances in multi-scale modeling and computational resources hold great promise for rapid progress toward these goals. In this presentation, we will discuss both the science questions that motivate the mesoscale opportunity and the potential impact of success in this pursuit.
A Brighter Future for Urban Water Systems
Dr. David Sedlak
Over the past 2,500 years, three technological revolutions have made it possible to quench the thirst of cities, control waterborne diseases, and eliminate the pollutants that fouled urban waterways. Water-stressed cities are currently making large investments in new, centralized approaches for obtaining drinking water that can be considered as a fourth urban water revolution. For example, cities in California, Texas, and Colorado are turning to the reuse of municipal wastewater, harvesting of urban runoff, and desalination of seawater to substitute for increasingly unreliable imported water sources. But this may not be good enough. Ultimately, challenges associated with climate change, sea-level rise and urbanization may create a need for yet another revolution. The best approach for responding to these challenges is still unclear, but distributed water treatment technologies, managed natural systems, and more holistic urban water management systems all have important roles to play in a fifth urban water revolution.
Million Person Study of Low Dose Radiation Health Effects (and Relevance to Space Travel)
Dr. John D. Boice, Jr.
A critically important gap in knowledge surrounds the health consequences of exposure to radiation received gradually over time. Much is known about the health effects of brief high dose exposures, such as from the atomic bombings in Japan, but the concerns today focus on the frequent low dose exposures received by the public, workers, and astronauts. Ever-increasing population exposures come from medicine (CT scans), nuclear waste and facility cleanups, nuclear power generation, occupation (interventional radiologists), increased air travel and cosmic-ray exposures, technologically enhanced naturally occurring radioactive materials (TENORM) in the environment from hydraulic fracturing, reactor accidents (Fukushima), and the possibility of terrorist events with dirty bombs or improvised nuclear devises. Additional guidance is needed by NASA for planning long-term missions where the rate of radiation exposure is low but the cumulative amounts potentially high.
Combustion Dynamics in Propulsion Systems
Dr. Vigor Yang
Unsteady flow oscillations, commonly known as combustion instabilities, were discovered in rocket and air-breathing engines in the late 1930s. Since then, combustion instabilities have plagued most, or in fact practically all, engine development programs. Indeed, because of the high density of energy release in a volume having relatively low losses, conditions favor excitation and sustenance of flow oscillations in any combustion chamber intended for use in a propulsion system.
This seminar will provide an overview of combustion instabilities in four different types of propulsion systems (solid rocket, liquid rocket, gas turbine, and ramjet/scramjet engines). Emphasis will be placed on the present understanding of the processes involved, and contemporary research needs and challenges. Various research issues in acoustics, fluid mechanics, and chemistry related to oscillatory combustion in practical systems will be discussed. Both passive and active control techniques will be covered. Applications of contemporary numerical schemes, approximate analytical methods, and experimental diagnostic tools to combustion instability studies will be addressed.
Tandem Reactions of Alcohols Derived from Renewable Biomass over Multifunctional Catalysts
Dr. Robert Davis
Alcohols can be produced easily from a variety of carbon sources, including renewable biomass. In this talk, the subsequent transformations of carbohydrate-derived alcohols via catalytic hydrogenolysis over bifunctional Pt-Re catalysts and coupling to longer chain alcohols over hydroxyapatite catalysts will be discussed. The bimetallic Pt-Re catalyst exposes a metallic Pt site that catalyzes hydrogen transfer reactions and an acidic site associated with oxidized Re that catalyzes dehydration. The effective pairing of the metal function with the acid function promotes the rate of glycerol hydrogenolysis and shifts product selectivity toward desirable 1,3-propanediol. The Guerbet coupling of ethanol to butanol requires a multifunctional catalyst that facilitates ethanol dehydrogenation, aldol condensation, and hydrogenation. Hydroxyapatite is an active and selective catalyst for the reaction because of its appropriate balance of Lewis acidity and basicity. General principles regarding tandem reactions in heterogeneous catalysis will be discussed.
Designing Ionic Liquids for CO2Capture
Dr. Joan Brennecke
Ionic liquids (ILs) present intriguing possibilities for removal of carbon dioxide from a wide variety of different gas mixtures, including post-combustion flue gas, pre-combustion gases, air, and raw natural gas streams. Even by physical absorption, many ILs provide sufficient selectivity over N2, O2, CH4 and other gases. However, when CO2 partial pressures are low, the incorporation of functional groups to chemically react with the CO2 can dramatically increase capacity, while maintaining or even enhancing selectivity.
We will demonstrate several major advances in the development of ILs for CO2capture applications. First, we will show how the reaction stoichiometry can be doubled over conventional aqueous amine solutions to reach one mole of CO2 per mole of IL by incorporating the amine on the anion. Second, we will show how we have been able to virtually eliminate any viscosity increase upon complexation of the IL with CO2, by using aprotic heterocyclic anions (AHA ILs) that eliminate the pervasive hydrogen bonding and salt bridge formation that is the origin of the viscosity increase. Third, we will describe the discovery of AHA ILs whose melting points when reacted with CO2are more than 100 °C below the melting point of the unreacted material. These materials allow one to dramatically reduce the energy required for CO2 release and regeneration of the absorption material because a significant amount of the energy needed for the regeneration comes from the heat of fusion as the material releases CO2 and turns from liquid to solid.
Solar Sails for Spacecraft Propulsion
Solar sails use sunlight to propel vehicles through space by reflecting solar photons from a large, mirror-like sail made of a lightweight, highly reflective material. This continuous photon pressure provides propellantless thrust, potentially enabling a solar sail propulsion system to propel a spacecraft to tremendous speeds—theoretically much faster than any present-day propulsion system and allowing for very high total-thrust maneuvers for long-duration deep space exploration. Since the Sun supplies the necessary propulsive energy, solar sails require no onboard propellant. Solar sail technology is rapidly maturing for space propulsion applications within NASA and may one day take us to the stars.
The Impact of Agriculture on Air Quality and Climate: Is Nitrogen the Next Carbon?
Dr. Viney P. Aneja
Agricultural air quality is an important emerging area of environmental science, which offers significant challenges to many aspects of research, policy and regulatory frameworks. Agricultural emissions produce significant local, regional and global impacts, such as odor, Particulate Matter (PM) exposure, eutrophication, acidification, climate change, exposure to toxics, and pathogens. Agricultural emissions are variable in space and time. Most important in the US are ammonia (where agriculture accounts for ~90% of total emissions), nitrous oxide (72%), reduced sulfur (unquantified), PM2.5 (~16%), PM10 (~18%), methane (29%); and odor and emissions of pathogens (both unquantified).
Reactive nitrogen inputs in US and the world have been increasing, largely due to human activities associated with food production and fossil fuel combustion. Excess reactive nitrogen threatens the quality of air, soil, and water; with implications for human health and the environment. It also contributes to the global problems caused by nitrous oxide greenhouse gas emissions. Despite the obvious benefits of a plentiful supply of food and energy, the adverse consequences associated with the accumulation of reactive nitrogen in the environment are large. Nitrogen pollution poses an even greater challenge than carbon, because once a new reactive nitrogen molecule is created, it can, in sequence, travel throughout the environment contributing to major environmental problems i.e. the nitrogen cascade. There is a need for an integrated nitrogen management strategy and new policies that cover these concerns; while simultaneously challenging the scientific community to continue quantifying the benefits of nitrogen mitigation.
At the Confluence: Nutrients, Trace Chemicals, and Sustainability in the Urban Water Sector
Dr. Nancy G. Love
Enhanced global urbanization coupled with the impacts of climate change on water infrastructure in cities will change how we design and operate urban water systems in the future. While climate change tends to be a discussion centered on carbon as the pollutant, the most critical decisions linked to achieving sustainable, energy efficient or net-energy neutral solutions in urban wastewater (or used water) systems tend to be driven by the need to manage nutrients (nitrogen and phosphorus).*
In turn, the current evolution in sustainable, energy recovering wastewater treatment or green infrastructure strategies are heavily influenced by the need to manage nitrogen and/or phosphorus, as much as if not more than carbon. Another area of tremendous focus regarding urban water infrastructure concerns the impact of trace chemical contaminants on environmental and human health. All these issues have reached a point of confluence.
Implementing innovative and energy efficient nitrogen or phosphorus management approaches involves dramatic changes to the infrastructure in place today, and in some cases results in significant changes in the composition of wastewater or the redox environments imposed during treatment. In turn, these changes influence the ultimate fate of trace chemicals present in wastewater or stormwater and, ultimately, the risks to environmental and public health in urban systems. This is particularly important for cities located in countries with emerging economies. The nature of this confluence of issues and trends will be introduced, and opportunities for solutions proposed.
VRB Energy Storage Performance Characterization for Microgrid Applications
Dr. Mariesa Crow
Energy storage technology is a critical aspect of future development of portable, scalable microgrid technology. One of the most important parameters in microgrid operation is the ability to predict the power and energy characteristics of any energy storage system. To achieve optimal use of renewable energy resources and energy storage, the energy storage system must be modeled accurately and must include all parasitic and operational losses from environmental controls. Furthermore, the energy storage operation must be modeled in conjunction with the particular renewable resource with which it will be used.
This seminar will discuss recent efforts to characterize the Vanadium Redox Battery (VRB) for microgrid applications. An electrical model of the VRB will be developed including charge and discharge efficiencies, balance of plant parasitics, and integration with photovoltaic systems. The model will be validated via a field demonstration at Fort Leonard Wood Army Base in Missouri. This model will be used as a basis for the development of a microgrid control strategy for heterogeneous energy storage systems, on and off-grid operation, and renewable energy.
An Integrative Engineering Approach to Neuromuscular Control
Dr. Francisco Valero-Cuevas
The study of how the nervous system controls our limbs began from biological and clinical perspectives, but the last half century saw much progress driven by an engineering approach. The diverse goals, assumptions, and methods of each of these fields has also led to some confusion. I will present two examples of how an integrative approach can reconcile divergent views on the fundamental nature of neuromuscular control. The first example presents basic concepts of the emerging field of neuromechanics to help clarify how the nervous system might select valid motor commands. The second demonstrates that neuromorphic implementations of even simple spinal reflexes produces stable and robust mechanical function. I will conclude by discussing some clinical applications of these concepts.
Challenges and Approaches for a Trustworthy Power Grid Cyber Infrastructure
Dr. William Sanders
The vision for a modernized “Smart Grid” involves the use of an advanced computing, communication and control cyber infrastructure for enhancing current grid operations by enabling timely interactions among a range of entities. The coupling between the power grid and its cyber infrastructure is inherent, and the extent to which the Smart Grid vision can be achieved depends upon the functionality and robustness of the cyber infrastructure.
This talk describes some of the research at the DOE- and DHS-funded Trustworthy Cyber Infrastructure for the Power Grid (TCIPG) Center which is aimed at ensuring that the power grid cyber infrastructure is protected both from accidental failures and malicious attacks from adversaries ranging from casual hackers to nation states. The goal of TCIPG is to provide resilience in the nation¹s electric grid cyber infrastructure such that it continues to deliver electricity and maintain critical operations even in the presence of cyber attacks. Achieving this goal will involve the extension, integration, design, and development of IT technologies imbibed with key properties of real-time availability, integrity, authentication and confidentiality.
The Future of Robotics is Swarms: Why a Thousand Robots are Better Than One
Dr. Jame McLurkin
Multi-robot systems are the future of a futuristic field. Large populations of robots can solve many practical applications faster, cheaper, and in fundamentally different ways than individual robots. The key to realize this potential are distributed algorithms, and a whole lot of really cheap little robots. These ideas aren’t new. Ants and bees have been using this approach for 120 million years, and we can learn much from them.
Tactile Feedback for Telerobotic Surgery
Dr. Katherine Kuchenbecker
Although commercial telerobotic surgery systems such as the Intuitive da Vinci are approved for use on human patients, they provide the surgeon with very little touch feedback. Measuring and recreating tool-tissue interaction forces is technically challenging, especially while satisfying the safety and sterility requirements of surgery.
Kuchenbecker’s research group at Penn has invented and studied two methods for adding tactile feedback to such systems. The first approach enables the surgeon to feel high-frequency instrument vibrations, which indicate important transitions in manipulation contact state that are often difficult to discern visually. They mount three-axis high-bandwidth accelerometers to the robot arms under the sterile draping; their outputs drive one-axis voice-coil actuators positioned on the surgeon hand controllers.
Recordings of live surgeries support the clinical feasibility of this approach. Other studies have demonstrated that surgeons significantly prefer this additional vibration feedback and that it has the potential to improve patient safety.
Their second approach to providing tactile feedback in telerobotic surgery centers on palpation, where the surgeon examines soft tissue using his or her fingertips. Working with the University of Siena, they mounted a biomimetic fingertip tactile sensor (SynTouch BioTac) to the end of a da Vinci instrument and attached a custom cutaneous display to the corresponding da Vinci master controller.
Using data recorded when the BioTac was inside the cutaneous display, their control algorithm finds the closest fingertip deformation experienced during calibration and drives the cutaneous display to the corresponding actuator outputs. A human-subject experiment with this system demonstrated that fingertip deformation feedback significantly improved the operator’s ability to locate a rigid object embedded in soft simulated tissue.