Information Structure Design in Team Decision Problems

We consider a problem of information structure design in team decision problems and team games. We propose simple, scalable greedy algorithms for adding a set of extra information links to optimize team performance and resilience to non-cooperative and adversarial agents. We show via a simple counterexample that the set function mapping additional information links to team performance is in general not supermodular. Although this implies that the greedy algorithm is not accompanied by worst-case performance guarantees, we illustrate through numerical experiments that it can produce effective and often optimal or near optimal information structure modifications

Branchings and Time Evolution of Reaction Networks

In this thesis I analyze flows in reaction networks in terms of branchings in a digraph. If the coupled differential equations governing the rate of change of probabilities X of a state or species are finite-differenced in time, a matrix equation (I + Adt)X(t+dt) = X(t) results, where X(t) is a vector giving the probabilities at time t and X(t+dt) is a vector giving the probabilities at time t + dt. I demonstrate that the matrix (I + Adt) may be written as the product of an incidence matrix and a weight matrix for a directed graph (digraph) representing the network. From this I demonstrate that individual diagonal elements of the inverse matrix (I + Adt)-1 may be written as a sum of the exponential weight of all branchings rooted at the vertex corresponding to the root vertex in the digraph divided by the sum of the exponential weight of all branchings. I also demonstrate that the individual element of the inverse matrix at row i, column j is the sum of exponential weights of all branchings rooted at vertex i but with a path from vertex i to vertex j in the digraph divided by the sum of exponential weights of all branchings. From this I demonstrate how to compute X(t + dt) from X(t) in terms of sums of branchings and how to compute effective transition rates. I then consider long-term solutions and demonstrate how to condense linear networks that obey detailed balance. This provides a useful connection to equilibrium analysis of the network. I then consider some implications of the branching analysis for the statistical mechanics of reaction networks, and I extend the analysis to non-linear networks. Finally I provide some example applications. I conclude that branchings in network digraphs hold promise for analyzing complicated reaction flows, and I list some future directions of possible research

An Improved Randomized Truthful Mechanism for Scheduling Unrelated Machines

We study the scheduling problem on unrelated machines in the mechanism design setting. This problem was proposed and studied in the seminal paper (Nisan and Ronen 1999), where they gave a 1.75-approximation randomized truthful mechanism for the case of two machines. We improve this result by a 1.6737-approximation randomized truthful mechanism. We also generalize our result to a $0.8368m$-approximation mechanism for task scheduling with $m$ machines, which improve the previous best upper bound of $0.875m(Mu'alem and Schapira 2007)

Discrete Ordinates Methods for Transport Problems with Curved Spatial Grids.

The method of characteristics (MOC) has been favored for many recent whole core transport codes; some current research codes are: the nTRACER code from Seoul National University, the MPACT code from the University of Michigan, and the Dragon code from Ecole Polytechnique de Montreal. However, it is well-known that whole core transport with MOC is both computational expensive and requires significant storage. On the other hand, discrete ordinates (SN) methods have been successfully applied to large systems, as has been demonstrated by the computer code Attila. However, all previous discrete-ordinates methods implemented in available production computer codes were formulated only for problems containing spatial cells with planar boundaries. This creates geometric approximations and inefficiencies for modeling any physical system with curved boundaries â the curved boundaries must be approximated using a greatly many very fine spatial cells, each fine cell having a planar boundary. In this thesis, we derive, implement, and test 2-D discrete ordinates methods, which are applicable for systems having curved interfaces between material regions, and which treat these curved surfaces analytically. The key benefits of "these" discrete ordinates methods on curved spatial grids over the MOC method include: (i) the ability to use standard highly-optimized quadrature sets, (ii) a single user-specified spatial grid, (iii) a simple extension to 3-D transport, and (iv) a small memory footprint for the computer.PhDNuclear Engineering and Radiological SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116757/1/chyliu_1.pd

Inhibition of the Fenton reaction by nitrogen monoxide

The toxicity of iron is believed to originate from the Fenton reaction which produces the hydroxyl radical and/or oxoiron(2+). The effect of nitrogen monoxide on the kinetics of the reaction of iron(II) bound to citrate, ethylenediamine-N,N′-diacetate (edda), ethylenediamine-N,N,N′,N′-tetraacetate (edta), (N-hydroxyethyl)amine-N,N′,N′-triacetate (hedta), and nitrilotriacetate (nta) with hydrogen peroxide was studied by stopped-flow spectrophotometry. Nitrogen monoxide inhibits the Fenton reaction to a large extent. For instance, hydrogen peroxide oxidizes iron(II) citrate with a rate constant of 5.8×103M−1s−1, but in the presence of nitrogen monoxide, the rate constant is 2.9×102M−1s−1 . Similar to hydrogen peroxide, the reaction of tert-butyl hydroperoxide with iron(II) complexes is also efficiently inhibited by nitrogen monoxide. Generally, nitrogen monoxide binds rapidly to a coordination site of iron(II) occupied by water. The rate of oxidation is influenced by the rate of dissociation of the nitrogen monoxide from iron(II

Safety Early Warning for Air Traffic Management

In recent years, with the rapid development of China's transportation industry, air traffic management has attracted more and more attention, and its safety problems have become increasingly prominent. In civil aviation transport, it mainly involves various types of transportation tools, such as high-altitude and long-span channels.Therefore, it is one of the most important contents to strengthen the safety management in the civil aviation transportation. Air traffic safety early warning management is not only related to the safety of the aircraft flight, but also can very good reflect the aviation technology level in our country, said from the book, the main content of air traffic safety management is to keep the normal order of air traffic, at the same time avoid mutual collision between all kinds of aircraft and obstacles, in the current situation, to strengthen the management of air safety early warning research is very important

A 5+ϵ-approximation algorithm for minimum weighted dominating set in unit disk graph

AbstractWe study the minimum weight dominating set problem in weighted unit disk graph, and give a polynomial time algorithm with approximation ratio 5+ϵ, improving the previous best result of 6+ϵ in [Yaochun Huang, Xiaofeng Gao, Zhao Zhang, Weili Wu, A better constant-factor approximation for weighted dominating set in unit disk graph, J. Comb. Optim. (ISSN: 1382-6905) (2008) 1573–2886. (Print) (Online)]. Combining the common technique used in the above mentioned reference, we can compute a minimum weight connected dominating set with approximation ratio 9+ϵ, beating the previous best result of 10+ϵ in the same work