2,389 research outputs found
Reduced Complexity Filtering with Stochastic Dominance Bounds: A Convex Optimization Approach
This paper uses stochastic dominance principles to construct upper and lower
sample path bounds for Hidden Markov Model (HMM) filters. Given a HMM, by using
convex optimization methods for nuclear norm minimization with copositive
constraints, we construct low rank stochastic marices so that the optimal
filters using these matrices provably lower and upper bound (with respect to a
partially ordered set) the true filtered distribution at each time instant.
Since these matrices are low rank (say R), the computational cost of evaluating
the filtering bounds is O(XR) instead of O(X2). A Monte-Carlo importance
sampling filter is presented that exploits these upper and lower bounds to
estimate the optimal posterior. Finally, using the Dobrushin coefficient,
explicit bounds are given on the variational norm between the true posterior
and the upper and lower bounds
Benefits of Industry Involvement in Multidisciplinary Capstone Design Courses
Opportunities for industry involvement in capstone design courses go beyond industry sponsorship of capstone design projects. Representatives from industry can serve as guest lecturers, curriculum advisors, and design project sponsors and team mentors. Since 2000, industry participation has been a core part of the capstone design course at Marquette University. Practicing engineers provide a relevant, practical real-world perspective of their topic, reinforcing its importance to professional engineering practice. Students and faculty benefit from the up-to-date treatment of the topic provided by guest speakers from industry who have expertise in the topic and are willing to share their experiences with students. Students benefit from industry sponsorship of senior design projects through the opportunity to work on realworld problems of importance to industry, exposure to industry and company-specific project management and product development processes, and familiarity with economic, legal, and regulatory design constraints. This paper provides a brief description of the Multidisciplinary Capstone Design course at Marquette University, examples of industry involvement in the course, and the observed benefits of industry involvement to students, the university, and industry participants. It presents examples of current practices used at other schools as well as helpful recommendations for managing industry participation in capstone design courses
Spin-String Interaction in QCD Strings
I consider the question of the interaction between a QCD string and the spin
of a quark or an antiquark on whose worldline the string terminates. The
problem is analysed from the point of view of a string representation for the
expectation value of a Wilson loop for a spin-half particle. A string
representation of the super Wilson loop is obtained starting from an effective
string representation of a Wilson Loop. The action obtained in this manner is
invariant under a worldline supersymmetry and has a boundary term which
contains the spin-string interaction. For rectangular loops the spin-string
interaction vanishes and there is no spin-spin term in the resulting heavy
quark potential. On the other hand if an allowance is made for the finite
intrinsic thickness of the flux-tube, by assuming that the spin-string
interaction takes place not just at the boundary of the string world-sheet but
extends to a distance of the order of the intrinsic thickness of the flux tube,
then we do obtain a spin-spin interaction which falls as the fifth power of the
distance. Such a term was previously suggested by Kogut and Parisi in the
context of a flux-tube model of confinement.Comment: 19 pages, 1 figure; Published version with added discussion and
references in section
Bifurcation in cell cycle dynamics regulated by p53
We study the regulating mechanism of p53 on the properties of cell cycle
dynamics in the light of the proposed model of interacting p53 and cell cycle
networks via p53. Irradiation (IR) introduce to p53 compel p53 dynamics to
suffer different phases, namely oscillating and oscillation death (stabilized)
phases. The IR induced p53 dynamics undergo collapse of oscillation with
collapse time \Delta t which depends on IR strength. The stress p53 via IR
drive cell cycle molecular species MPF and cyclin dynamics to different states,
namely, oscillation death, oscillations of periods, chaotic and sustain
oscillation in their bifurcation diagram. We predict that there could be a
critical \Delta t_c induced by p53 via IR_c, where, if \Delta t < \Delta t_c
the cell cycle may come back to normal state, otherwise it will go to cell
cycle arrest (apoptosis)
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Techniques for Detection of Malicious Packet Drops in Networks
The introduction of programmability and dynamic protocol deployment in routers, there would be an increase in the potential vulnerabilities and attacks . The next- generation Internet promises to provide a fundamental shift in the underlying architecture to support dynamic deployment of network protocols. In this thesis, we consider the problem of detecting malicious packet drops in routers. Specifically, we focus on an attack scenario, where a router selectively drops packets destined for another node. Detecting such an attack is challenging since it requires differentiating malicious packet drops from congestion-based packet losses. We propose a controller- based malicious packet detection technique that effectively detects malicious routers using delayed sampling technique and verification of the evidence. The verification involves periodically determining congestion losses in the network and comparing the forwarding behaviors of the adjoining routers to affirm the state of a router in the network. We provide a performance analysis of the detection accuracy and quantify the communication overhead of our system. Our results show that our technique provides accurate detection with low performance overhead
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