NARC Seminar Series - Abstracts AY09
Professor Craig M. Whitaker
Synthesis of Functionalized Single-Wall Carbon Nanotubes
Professor John A. Burkhardt
Quantifying Uncertainty in Computer Simulations
Associate Professor David S. Miklosovic
Analytic and Experimental Investigation of Dihedral Configurations
An analytic and experimental effort was undertaken to assess the effectiveness and efficiency of three winglets mounted chordwise to the tip of a rectangular wing. Thirteen configurations of varying dihedral arrangements were analyzed with a vortex lattice method and tested in a low-speed wind tunnel at a Reynolds number of 600,000. While the analytic method provided fair agreement with the experimental results, the predicted trends in lift, drag, and (to a lesser degree) pitching moment were in good agreement. The analytic distributions of wake velocity, circulation, and downwash angle verified that highly non-planar configurations tended to reduce and diffuse the regions of highest circulation and to create more moderate downwash angles in the wake. This was manifest as an overall drag reduction. More specifically, the results showed that the winglets could be placed in various optimum orientations to increase the lift coefficient as much as 65% at the same angle of attack, decrease the drag coefficient as much as 54% at the same lift coefficient, or improve the maximum L/D by up to 57%. The most dramatic findings from this study show that positioning the winglet dihedral angles had the result of adjusting the magnitude and slope of the pitching moment coefficient. These observations suggest that multiple winglet dihedral variations may be feasible for use as actively controlled surfaces to improve the performance of aircraft at various flight conditions and to “tune” the longitudinal stability characteristics of the configuration.
Assistant Professor Joshua J. Radice
On the Fully Elastic Model of the Square End Adhesive Layer
The square-end adhesive geometry idealization has been demonstrated to be the worst-case scenario for adhesive layer stress states in bonded structural assemblies. It has also been postulated that there exist infinite stress singularities at the sharp corners of the square-end adhesive layer. In an effort to evaluate these issues, a fully elastic analytical solution is derived for the deformation fields in this square end configuration. Using this fully elastic model, the deformations, infinitesimal strains, and key components of the stress tensor are compared to the prevalent adhesive layer models in the literature. Solution convergence is evaluated. Finally, using this fully elastic solution, the existence of stress singularities at the sharp corners of the square end adhesive layer is evaluated.
16 October 2008
Professor Nancy A. Mace
The Market for Printed Music in Late Eighteenth-Century England
Assistant Professor Joan Chevalier
Language Maintenance and Shift in the Republic of Tyva:
The goal of this project is to assess the impact of republic language educational policies introduced to foster Tuvan language maintenance. Beginning in 1991 the Republic of Tyva instituted an ambitious program to reinvigorate Tuvan language study in secondary schools. This research will focus on the content of these reforms, examine their success and failures, and evaluate the role of educational programs in Tuvan language maintenance.
Associate Professor Joseph J. Gwara
Grotesque Woodcut Initials and Sorts for w in Sixteenth-Century English Books
In this presentation, I describe two concurrent research projects on sixteenth-century English printing. The first is a catalogue of the grotesque woodcut initials found in English books printed between 1502 and c. 1570. I show that the grotesques can be used to date undated books, assign anonymous books to known printers, and explain anomalous textual features. The second project is a study of w-sorts (individual pieces of cast metal type for the letter w) used in English books printed between 1500 and 1550. An analysis of foul w-sorts has allowed me to detect many shared editions and to explain the evolution of the fonts used by the second generation of English printers.
23 October 2008
Assistant Professor Sommer E. Gentry
Towards an Online Matching Scheme for Kidney Paired Donation
Kidney paired donation (KPD) matches a recipient and his incompatible donor to another pair with a complementary incompatibility, such that the yudonor of the first pair gives to the recipient of the second, and vice versa. We propose a radical alternative to our own graph maximum matching model of paired donation, in which all arriving pairs wait for a significant number of pairs to accumulate before matching decisions are taken. Rather than use maximum matching, we use Markov Decision Process (MDP) models, in which a sequence of decisions which are made as a sequence of random variables are observed. A good policy for a kidney paired donation MDP model might allow some, but not all, feasible paired donation matches to proceed to transplantation as soon as they are discovered. Each pair as it arrives has an observable probability of being mutually compatible with any other pair. The types of paired donations which could proceed immediately might be those in which at least one of the pairs is a difficult-to-match pair. In contrast, two pairs which are easy to match might be better reserved for later arrivals who will be looking for one of those particular pairs as a needle in a haystack.
Associate Professor Paul T. Mikulski
The Effects of Interface Structure on the Friction
Molecular dynamics (MD) is a computational technique where simulations are carried out on model systems of about 10,000 atoms or greater (sometimes much greater) using classical empirical models of atomic interactions. In this study, the MD technique was used to compare the frictional properties of atomic-scale systems in sliding contact. The emphasis of this talk here will be on the creativity and thoughtfulness required to analyze simulation data. In particular, contact forces are defined and then shown to be useful in connecting friction versus load trends with atomic-scale features.
Associate Professor Clare E. Gutteridge
Antimalarial Drug Discovery
Malaria kills over 1 million people each year. There is a need for new drugs to combat the disease since resistance to existing drugs is significant. To be beneficial, any novel antimalarial drug needs to have a reasonably simple chemical structure. In collaboration with US Army researchers, we have been exploring several such classes of compound with the aim of developing a new antimalarial treatment. This talk will outline how new compounds are produced and tested, both in a test-tube and later in mice infected with malaria, and summarize progress to date.
30 October 2008
The idea of using automated vehicle platoons to alleviate traffic congestion has been pursued for many years. A fully automated system would enable more cars to be moved into a fixed space, leading to reductions in gridlock and increases in throughput. Another potential application is the automation of military supply convoys. While the ideal design may not be a fully automated system – perhaps a human operator will be needed in the lead vehicle – the architecture developed here could be used to design a control system of follower vehicles. This could reduce the number of people needed to staff the convoys or free the drivers to perform reconnaissance, take defensive positions, etc.
The goal of the proposed research is to design an overall control architecture for automated vehicle convoys that will maximize the “safe operating zone” while minimizing the number of sensors needed. The feedback controller will be used to maintain the desired velocity of the lead vehicle and the desired spacings of the following vehicles. The only required sensors will be a tachometer to measure the lead vehicle’s speed and range finders to measure the inter-vehicle spacing. Command shaping will be used to limit the error propagation through the string during transitions between desired velocities and vehicle spacings. Initial results show that command shaping can reduce both the velocity and spacing errors in vehicle platoons. Ongoing research involves concurrently developing feedback control laws and command shapers for optimal platoon performance.
Goodness-of-fit methods involve determining whether a sample of data come from a certain distribution -- imagine testing to see if student exam scores follow a bell-shaped curve. Jager and Wellner (2007) introduced a generalized family of goodness-of-fit statistics, but also showed that the asymptotic results are not very accurate, even for sample sizes as large as 1,000,000. Methods have also been developed to calculate results for samples smaller than 1,000. However this leaves a large range of sample sizes where the methods cannot be accurately applied. Applications of these statistics to large-scale multiple testing problems, such as those found in genetics and genomics, typically involve samples sizes in this problematic range. We will discuss extension of the small sample methods to sample sizes up to 10,000, as well as some consideration for extension beyond this range.
Assistant Professor Sophia T. Santillan
Nonlinear Elastica Analysis of Highly Deformed Structures
The study of beam stability and vibration is important in structural engineering and design. Knowledge in this research area is extended here by examining the nonlinear behavior of large beam deformations with an eye to new designs and applications. Numerous studies of nonlinear beam vibrations and solution approximation methods appear in the literature. Many of the studies have been performed using Eulerian (rather than Lagrangian) coordinates (or variables), limiting the vibration amplitudes and static deflections that may be considered. Here the beam studied is assumed to be inextensible, and shear deformation is neglected. The beam is modeled as an elastica, where the motion is assumed to be in-plane. Perturbation and finite difference methods are applied to study large-amplitude, in-plane vibrations of the beam for various boundary condition and self-weight cases. The self-weight of the beam is included in the equations. Because the elastica equations do not limit the amplitude of motion, they can be used to accurately describe motion with a large range of deflection sizes.
One application of highly deformed structures studied here is that of flexible risers and pipelines. The theoretical formulation leads to a type of nonlinear boundary value problem that can be solved numerically given appropriate boundary conditions. The offsetting effects of gravity and buoyancy are included in the analysis. These forces can provide considerable axial loading (as can thermal changes) and hence stability (buckling) is a major concern. Initial studies are based on the planar problem. A free-vibration analysis is also conducted for small-amplitude oscillations about various deflected equilibrium configurations in terms of natural frequencies and corresponding mode shapes. Energy dissipation and fluid forces are a key issue in the forced problem, especially when large deformations are involved . Knowledge of free vibration behavior is a vital prerequisite in understanding the response of these types of structures in practice.
6 November 2008
Assistant Professor Erica L. Zimmerman
Discovering the Co-construction of Family and Family Practices
This study is particularly interested in the extent family-like relationships are constructed in the context of a study abroad homestay situation. The analysis examines the displays of identity through sequential turns of talk and the use of addressee and reference terms. The data is based on two segments of multiparty talk in a host family situation in Japan. The participants are a Korean exchange student and her Japanese host parents. The results show that the participants constructed membership to the categories of "ordinary" or "special family member." The addressee and reference terms function as attention-getting devices for seeking alignment, for clarification of who the talk is about or addressed to in the local talk, and for co-constructing the point of the talk to indicate an arrival at a shared understanding of a situation.
Assistant Professor Brendan J. Dougherty
The Politics of the Permanent Campaign:
In recent years, a good amount of scholarly and journalistic attention has focused on what has been dubbed a permanent campaign for the presidency. According to this view of presidential governance, "the line between campaigning and governing has all but disappeared, with campaigning increasingly dominant" (Ornstein and Mann 2000, vii), and the techniques and strategies of presidential campaigning are applied throughout the course of a president’s term.
In this study, I undertake an empirical assessment of the evolution of two key elements of the permanent campaign for the presidency by systematically examining presidential travel and fundraising from 1977 through 2004. I find that presidential travel does target large, competitive states, and such strategic targeting has increased over time. Additionally, fundraising travel has grown substantially over time and occurs throughout a president’s term, supporting the notion that the permanent campaign is on the rise. However, substantial differences between reelection and other years, as well as measures of the breadth of presidential travel and proportional attention to the states, indicate that electoral concerns do not thoroughly permeate patterns of presidential activity throughout a president’s years in office, as the logic of the permanent campaign would suggest.
When an economic exchange requires agreement by multiple independent parties, the potential exists for an individual to strategically delay agreement in an attempt to capture a greater share of the surplus created by the exchange. This "holdout problem" is a common feature of the land assembly literature because development frequently requires the assembly of multiple parcels of land. We use experimental methods to examine holdout behavior in laboratory bargaining games that involve multi-person groups, complementary exchanges, and holdout externalities. We vary the bargaining institution, number of bargaining periods, number of sellers, and the cost of delay.
20 November 2008
Assistant Professor Cecily Steppe
Physical and Ecological Connectivity Among Restored Oyster Bars
In an effort to improve water quality and enhance the Crassostrea virginica fishery, many oyster restoration bars have been placed in Chesapeake Bay tributaries. Nevertheless, bars are often placed in sub-estuaries with poorly described circulation dynamics. Therefore the potential for the restored bars to either re-seed themselves or serve as larval sources for other beds remains unclear. To address this problem we assessed connectivity among 3 restored oyster bars in the Severn River Estuary, (Maryland, USA) via a combination of weekly plankton tows at each bar (College Creek, Weems Creek, and Lake Ogleton; May-October 2007); predictions from a hydrodynamic model (ADCIRC) adapted for the study area; and satellite-tracked drifter deployments from the College Creek and Weems Creek sites (2007-2008). Planktonic assemblages were similar among sites, and shifted on a time scale of weeks. Preliminary model runs showed that connectivity between the Weems Creek site and the main-stem of the Severn River may be higher than between the College Creek site and the Severn. Finally, drifter trajectories indicated two distinct transport regimes; retention within the Severn River system, on a time scale pertinent to C. virginica larval development (about 3 weeks), and export to the main-stem of Chesapeake Bay, indicating loss of larvae from the local system, either by mortality or recruitment to another sub-estuary.
Assistant Professor David W. Fredriksson
Hydrodynamics in a Chesapeake Bay Tributary from a “validated” Circulation Model with Particle Tracking Simulations
The objective of this project was to estimate hydrodynamic characteristics in the Severn River by validating numerical model results with field measurements and by simulating particle trajectories. The approach was to (1) compile existing numerical model and observational data sets, (2) validate a new Severn River circulation model with measurements and (3) produce a hydrodynamic data set for input to a particle tracking model. Systematic field measurements were made with an Acoustic Wave and Current Sensor obtaining surface elevation and depth averaged current velocities. A representation of the Severn River was then created using the ADvanced CIRCulation (ADCIRC) model. The ADCIRC model was forced at the open boundary with surface elevation data from a local tide station. Depth averaged velocities calculated with the model were then compared with those measured. Using the ADCIRC model domain with specific hydrodynamic results, a particle tracking model was configured. Trajectories were then simulated for small, neutrally buoyant particles.
The Kadison-Singer Extension Problem (KS for short) is a famous unsolved problem in the theory of operator algebras, dating to 1959. It concerns the pure states on B(l^2), the bounded linear operators on the infinite-dimensional Hilbert space l^2. In 1979, Joel Anderson proved that KS is equivalent to the Matrix Paving Problem. The latter asks whether there exists a real number 0 < r < 1 and a natural number k such that every zero-diagonal matrix has k-paving constant less than or equal to r. Though equal in difficulty to KS, the Paving Problem is much more concrete. Concerning the Paving Problem, it is known that k = 2 does not work for any r, but whether or not k = 3 works for some r is still open. In this talk, I will describe joint work with Gary Weiss (Univ. of Cincinnati) aimed at computing 3-paving constants (a 3-paving constant of 1 would show that k = 3 doesn’t work for any r). I will show that every 5-by-5 zero-diagonal matrix has 3-paving constant less than or equal to 0.6180 (the Golden Ratio) and that every 6-by-6 zero-diagonal matrix has 3-paving constant less than or equal to 0.7071 (= 1/√2). On the other hand, I will produce a 13-by-13 zero-diagonal unitary circulant with 3-paving constant 0.8615. This is the worst-known 3-paver discovered by anyone so far.
15 January 2009
Assistant Professor Ahmed S. Rahman
An Economic History of Biased Technological Change
Many issues in economics can be addressed by observing and modeling the skill-bias of technological progress. I focus on two such issues. The first deals with the nature and timing of the Industrial Revolution, which created some puzzling time series such as falling relative returns to skilled work and non-monotonic fertility patters. The second deals with the nature of technological progress in the U.S. Navy during the late 19th century. Constructing a growth theory in the first case and a unique dataset for empirical study in the second, I explore the historic role of skill-bias technological change in Western economic history.
Associate Professor William N. Traves
Hyperplane arrangements have recently been the subject of intense mathematical study, with applications ranging from robotics to political science. I'll define hyperplane arrangements, give a summary of some of their applications and close with an announcement of a groundbreaking result due to myself and Max Wakefield (also at USNA).
22 January 2009
Assistant Professor Ryan R. Brady
Econometric Measurement of Macroeconomic Shocks:
I summarize the primary focus of my research, which uses time series techniques to identify and measure the effects of real and monetary shocks on various macroeconomic data. I discuss two examples with respect to consumer lending and to housing prices. The former study considers the effect of monetary policy on consumer lending over the past thirty years; the latter study provides estimates of the effect of a shock to a region's average housing price level on adjacent regions.
Nuclei are known to take on very various shapes which include spherical, prolate (similar to a rugby ball), oblate (doorknob), octupole (pear), and triaxial (kiwi fruit). In fact, the same nucleus can exist with different shapes depending on its excitation energy and which nucleons are unpaired. Very recently, point-group theory calculations suggested that nuclei with certain values of Z (number of protons) and N (number of neutrons) may have shapes that stabilize as very-rounded pyramids when they are highly excited. If true, such nuclei would be the result of the most high-ranked symmetry class of shapes observed (tetrahedral symmetry), and would be extremely exotic. Unfortunately, the calculations predict that most of the best cases cannot be produced with current accelerator technology. However, there may be evidence of tetrahedral symmetry in the rare-earth region (Z ~ 64) when the nuclear system possesses 90 neutrons. A series ! of! experiments on one of these nuclides (156Dy) has begun in order to prove (or disprove) this hypothesis. Highly-excited nuclear states were populated with the 12C + 148Nd reaction and the emitted gamma rays were detected with Gammasphere (the world's largest gamma-ray detection facility) at Argonne National Laboratory. The ideas behind the pyramid-shaped nuclei and early results from the first experiment will be discussed.
This talk will discuss the Spacewatch Project and the operations of Near-Earth asteroid surveys in attempting to understand the asteroid hazard. In particular we are currently engaged in trying to measure the size and orbital element distribution of the Near-Earth asteroids using over 10 years (12 Tb) of Spacewatch imagery. The analysis is complicated by observational bias -- large and close asteroids are easy to detect and so we quickly find most of them, while other asteroids are small or spend a lot of time far away from the Earth so they are hard to detect. Even a single detection of the latter class can imply a huge undetected population. We describe the debiasing simulation we are currently performing and present preliminary results from a subset of our data.
26 January 2009
Visiting Professor Mary E. Burfisher and Professor Karen
Undergraduate Teaching Tools for Computable General Equilibrium Models
The objective of this project is to develop technology-based learning materials to assist advanced undergraduate economics students in integrating and applying their knowledge of economic theory to real-world economic problems through the use of computable general equilibrium (CGE) models. CGE models are applied, economy-wide analytical tools that provide a theoretically consistent framework for simulating the microeconomic behavior of consumers and producers constrained by the macroeconomic equilibrium of a country's income and expenditure, savings and investment, and capital and current accounts. With appropriate supporting learning materials, CGE models can be used as applied learning tools to help students integrate and deepen their comprehension of different subject areas of economic theory, leading them from novice toward expert economic thinking as they learn to apply their theoretical economics knowledge in quantitative simulations of realistic economic problems.
The new availability of compatible and intuitive CGE modeling software and the growing accessibility of data create an opportunity to use CGE models as a hands-on pedagogical tool at the advanced undergraduate level. These advances in modeling and data allow students to learn the mechanics of CGE modeling relatively quickly, freeing them to focus on the structure and behavior of the economy that they are studying. The model can be utilized as an economics laboratory in which students can visualize and learn to control theoretically-derived microeconomic behavior, define relevant scenarios such as tax changes or productivity growth, and make theoretically-based predictions about expected model outcomes. The complexity of a multi-sector, open economy model presents challenges as students learn to be discriminating in identifying results that are relevant to their research question and experiments.
Interpretation of results requires that students understand and explain the underlying principles driving producer and consumer behavior. Eventually, students move toward a general equilibrium perspective to fully explain their results, including the linkages among sectors through intermediate demands and competition for factors of production, and the role of macroeconomic effects such as exchange rates' influence on supply and demand for both traded and nontraded goods. In this process, students learn to integrate their knowledge of different areas of economic theory and to see economic stories at play in a complex economy.
Professor Helen E. Purkitt
Tracking Transnational Illicit Networks
During 2007/08 midshipmen and faculty affiliated with the USNA Political Science Deptartment have worked on a project designed to learn how to most effectively use computer-based collaborative methods to analyze complex political/intelligence questions. Last year's effort was a collaboration involving midshipmen and graduate students affiliated with Syracuse University. The two groups of students conducted parallel case studies of ungoverned and urban 'black spots' where jihadist terrorists might be researching and developing WMDR. The results were summarized using two different template designs in a specialized wiki. This year colleagues from Computer Science and Mathematics have involved in a related project that is designed to identify and analyze links among transnational illicit networks of government officials, smuggling networks (e.g., drugs, arms, people, endangered species, etc.), etc) and jihadist terrorists, working in Latin America or Africa (Guinea Bissau, South Africa), who might cooperate in the future to smuggle a WMDR or conventional weapon into Europe or the United States. The presentation summarizes the specialized wiki data bases developed and lessons learned to date.
The impetus behind this project lies in recent studies of the Nazi German economy which argue that the need to overcome the technological deficit built by the Western Allies in anti-submarine warfare by1943 triggered a shift in U- boat design and production. An emphasis on technological solutions to strategic and operational problems, to say nothing of Nazi Germany's economic difficulties, had by that point become a hallmark of Nazi thinking. (another excellent example of which was the role of the Tiger and Panther tanks at Kursk, neither of which proved decisive to the outcome). This view writes off the views of Richard Overy in particular, which point to the failure of the regime to develop positive relationships between industry and the war effort as reflecting a "peculiar irrationality of the 'Nazi social system.'" It argues that exaggerated technological expectations lay in Germany's hopeless strategic dilemma and that the systems themselves, while promising, were rushed into production without adequate testing and development. This interpretation also attributes the decision to embrace the radical new Type XXI submarine in 1943, under the technocratic direction of the Speer ministry, as reflecting both the unreality of German armaments propaganda and the progressively authoritarian cast of the war economy.
12 February 2009
Michelle G. Koul
Environmental Influences on Material Integrity
High strength alloys under certain environmental conditions can be susceptible to phenomenon called environmentally assisted cracking (EAC). This particular phenomenon involves the combined effects of electrochemical corrosion and applied mechanical stress that result in a decreased fracture resistance of a material. The use of new alloys on Naval platforms is often curtailed by a limited understanding of the conditions under which EAC will occur. This presentation will describe a variety of funded efforts conducted at USNA that involve the experimental evaluation of the effect of seawater on the cracking of structural alloys.
Professor Sarah E. Mouring
The Role of Advanced Composites in the U.S. Navy
In the marine industry, advanced composites are being used more often compared to traditional materials due to their increased strength- and stiffness-to-weight ratios, corrosion resistance, ability to tailor properties, and improved stealth characteristics needed for military applications. Despite these advantages, their use on large-scale structures as primary members has been restricted in the offshore industry. Naval applications have recently increased from the traditional mine countermeasure vessels to large hangers on destroyers. Many other naval applications are being proposed and a large volume of research is currently being undertaken. In this presentation several different research projects will be reviewed including two recent ONR-sponsored projects. The first project examined the effects of low-velocity impact loading on the behavior of large-scale composite panels. The second project is ongoing and examines the integrity of hybrid metal-to-composite connecti! on! details under static and dynamic loading regimes.
Associate Professor Matthew G. Feemster
Cooperative Manipulation on a Marine Vessel
In this presentation, we will provide an overview of results of our investigation into the utilization of a swarm of autonomous tugboats to manipulate a disabled (or unactuated) marine vessel. Specifically, the design of a cooperative control algorithm that executes on each autonomous tug such that the combined thrust of the swarm produces a desired force vector and torque on the disabled vessel is discussed. In addition, this control algorithm must also accommodate for such effects as: 1) unidirectional thrust input (i.e., the tugs cannot pull on the vessel hull), 2) thrust saturation, and 3) unknown hydrodynamic coefficients. Experimental modeling and testing on the Severn River will be included. Ongoing work in this area will also be discussed.
2 April 2009
A preliminary method validation study was conducted in order to test a new patent pending optical enzyme sensing method for detecting total coliforms and E. coli under typical estuarine conditions (Pathogendetection INC.). The Pathogendetection method was tested against the EPA approved standard method developed by the HACH corporation known as the m-coli blue method. Results suggest that the optical enzyme sensing method tends to greatly over predict concentration of both total coliforms and especially E. coli in a saltwater matrix. Further tests are necessary to determine if and what kind of potential saltwater matrix maybe interfering with the instruments capability of sensing the enzyme release. Modeled growth curves are for freshwater only, and a new calibration curve for total coliform and E. coli growth across a range of salinities will have to be developed.
Over the past decade, techniques from dynamical systems theory have been effective in quantifying mixing and transport of various fluid flows. The approach is appealing due to the ability to analyze complex time-dependent Eulerian fields by observing the evolution of the separatrices or manifold structures. This talk will review the techniques to develop stable and unstable manifolds for a simple 2-D time dependent double gyre flow. The evolution of these manifold structures will then be used to analyze fluid transport using the turnstile mechanism. An alternative technique to find the locations of manifolds utilizing the computation of Lagrangian Coherent structures is investigated. Finally, preliminary work on the application of both of these theories to examine model-assimilated data over a finite time period in the Gulf of Mexico is discussed.
A significant obstacle in understanding processes in the ocean surface boundary layer is the lack of knowledge about the interaction between surface gravity waves and turbulence. Turbulence in the uppermost layer of the ocean governs many processes such as air-sea gas exchange, transport of momentum and heat and mixing and transport of surfactants. Therefore, understanding the generation and structure of turbulence in the presence of surface waves is crucial both for understanding the above mentioned physical processes and for their accurate parameterization in numerical models. This talk will review the previous studies on wave turbulence interaction and discuss an experimental research plan including field (Chesapeake Bay) and laboratory (USNA Tow tank) program to address some of the unresolved issues.
9 April 2009
Assistant Professor Darrell J. Glaser
Time-interacting Effects of General and Corps-specific Human Capital
This paper extends earlier research on 20-year retention rates of Marine Corps officers particularly allowing for time-variation in the estimation of coefficients. Estimation methods control for time-dependent observed heterogeneity and produce results theoretically more consistent than previous studies. Career paths (MOS), marital status, the number of dependents and external labor market conditions change over the course of officer careers, and including covariate functions of time produces strikingly different results. Even seemingly constant covariates (e.g., commissioning source, choice of college major) affect baseline separation rates differently as time progresses. In particular, high-value human capital acquired prior to commissioning induces officers to separate at faster rates, however, the effect of this general training depreciates with time. The development of firm-specific human capital while at Marine Basic School (TBS) has stronger long-run effects, where better TBS performance implies lower rates of separation over most of a career. Of additional consequence, the method of job selection based on trecile splits employed by the Marine Corps at the conclusion of TBS appears efficient. Of tangential importance, external shocks to labor demand affect exit rates, with evidence suggesting that higher unemployment rates lead to lower rates of separation. After September 2001, there is mild evidence that shocks to labor supply outweigh demand shocks induced by the recent military conflicts for mid-level officers.
Assistant Professor Catherine O'Neil
Literary Politics in Russia and Poland:
The national mythology generated by the first Polish uprising against Russia (1830-31) has impacted the Poland's self perception to the present day. The analogies gleaned from classical history and tragedy, ranging from the Battle of Thermopylae to Aeneas' founding of Rome, are widespread in Polish intellectual history. Perhaps less known is the heroic and tragic image of the uprising in Russian literature and its role in the development in Russian political poetry.
In this presentation I examine the theme of "family tragedy," a well-known trope in both Polish and Russian treatments of the Polish Uprising. This motif is most famously treated in Polish poet Juliusz Slowacki's "Agamemnon's Tomb" (1839) and most infamously reflected in the Russian poet Pushkin's "To the Slanderers of Russia" (1831). In addition to these canonical texts, so crucial to national self-identity in Poland and Russia alike, I will discuss a lesser-known poem by Fyodor Tiutchev, "Agamemnon's sacrifice" (1831). The importance of Tiutchev's work in Russian political thought has been extensively studied (his massive but incomplete tract, Russia and the West, has enjoyed republication and healthy sales in Russia this past year), but his treatment of Poland and Greece have not been closely investigated before.
During the first decades of the twentieth century, Argentina experienced a multitude of hyperbolic changes--economic, social, political, cultural and physical--all of which are reflected in the work of the period's most prominent writers. The aesthetic innovations of the period have been studied in terms of those contextual changes, but the question of their ethical resonance remains largely unexplored. The thrust of my research is to cast the poetic daring of a diverse group of these writers in ethical terms; my theory being that their efforts constitute, in part, individual campaigns to render literature as an alternative to ethical discourse.
Up to this period, ethics in Argentina was the exclusive province of religious and philosophical tracts. My contention is that the poetry, drama, prose and journalism of the writers I study was an open, conscious attempt to wrest ethics from philosophy and religion, which these writers regarded as largely failed discourses. Even with the most politically and socially conservative of these writers, therefore, ethics is approached as a highly unstable field, one that can only be fruitfully developed by accepting the fundamental ambiguity and uncertainty of human circumstances and perspectives.
Accordingly, these Argentine writers of the period 1910-1940 were often radical in their subject matter as well as being experimental and innovative in style. In my brief talk, I discuss the ethical implications in the works of two such writers. Roberto Arlt produced novels, short stories and opinion columns that even today are noteworthy for their shocking subject matter--ranging from serial murder and child abuse to vigilante justice--as well as their frank, often profane language. Arlt, I argue, mercilessly shredded social and cultural sensibilities in order to force a complete rethinking of ethical method from its very foundations. He insists on the acknowledgment of moral ambiguity and contextual moral judgment prior to any attempt at ethical thinking.
Alfonsina Storni is regardly almost exclusively as a pioneering feminist who cleverly used her renown as a voice of appropriately female emotional sensibilities to forge a feminist agenda. My contention is that Storni regarded her feminist poetics--and her consequently avant-garde poetry--as inseparable from a greater concern over the ethical assumptions supporting Argentine society and culture. Her varied and persistent attacks on patriarchy were also efforts to "start over" in the pursuit of a workable contemporary ethics. The self-remaking and repositioning of women in a near social and cultural vacuum was prerequisite to any attempt at ethical discourse. Both authors, I further observe, share traits with the earliest stirrings of existentialist thought in Europe, built on a foundation of deep skepticism.
16 April 2009
Assistant Professor Adina Crainiceanu
P2P Range Index Structures: A Comparative Performance Analysis
Peer-to-peer (P2P) systems became famous (and infamous) due to Napster and other file-sharing applications. However, the main properties of P2P systems, namely robustness, scalability, decentralization, make them useful to a larger class of applications. We believe that future P2P applications, such as military applications, digital libraries, or resource discovery on a grid, will require complex query functionality. Several index structures were proposed to allow fast access to distributed data. We introduce a general, modular indexing framework that identifies and separates the different functional components of a P2P index structure. This framework allows reusing existing algorithms for different components rather than implementing everything anew. Moreover, the framework allows experimenting with different implementations for the same component so that the benefits of a particular implementation can be clearly evaluated and quantified. We introduce then P-Ring, an ind! ex! ! st! ! ructure that supports range queries in addition to equality queries, is fault-tolerant, efficiently supports large sets of data items per peer, and provides guaranteed logarithmic search performance. We show results from an experimental evaluation of P-Ring and several other P2P index structures: Skip Graphs, Online Balancing, Baton*, and Chord.
The research concerns a systematic investigation of ship air wakes using an instrumented USNA Yard Patrol (YP) craft to develop Computational Fluid Dynamics (CFD) tools that would be useful in determining ship air wake impact on naval helicopters. Currently, ship launch and recovery wind limits and envelopes for helicopters are determined through in situ flight testing that is expensive and frequently difficult to schedule and complete. The time consuming and potentially risky flight testing is required as computational tools are not mature enough to adequately predict air flow and wake data in the lee of a ship with a complex superstructure. The superstructure of USNA YPs is similar to that of modern destroyers and their size allows for collection of air wake data that is in the same order of magnitude of as that of modern naval warships, an important consideration in aerodynamic modeling. Furthermore, existing YP can be inexpensively modified to add a representat! iv! e flight deck and hanger structure that would model those on modern USN ships and provide enhanced measurement fidelity. After installing appropriate wind velocity and direction measuring equipment, testing of the modified YP would be conducted in the Chesapeake Bay, which would allow for the collection of data over a wide range of wind conditions. Direct measurement of ship air wake impact on a small rotary wing Unmanned Aerial Vehicle (UAV) will also be conducted. Concurrent with the collection of air wake data, a scale model of the modified YP would be constructed for testing in the large USNA wind tunnel. Comparison of YP in situ testing data with wind tunnel data would be useful for validation of wind tunnel test methods and scale effects, as well as CFD models that could help predict ship air wake effects. USNA Midshipmen will be involved in all aspects of collecting ship and wind tunnel data and in subsequent data analysis.