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Search Results: 1 - 10 of 325482 matches for " S. S. Liaw "
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Self-organization behavior in a constrained minority game
C. Liu,S. S. Liaw
Physics , 2006,
Abstract: In the standard minority game, every agent switches to his best strategy in hand at each time step. If only a small number of agents are allowed to switch their strategies at each time step, the population variance of the system plunges. The variance reaches a low value and remains steady for a period of time. Then without any sign it starts to rise abruptly to a high value and then decreases smoothly to the previous low value again. The process of an abrupt rise followed by a gentle decrease repeats again and again but without obvious characteristic length as time goes on. The phenomenon is similar to the collapse of a sand pile with sands being added continuously from the top. We define the scale of collapse of the population variance by the difference of the variance before and after an abrupt rise. We then find that the logarithmic plot of the frequency versus scale of the collapses follows a power law.
Effective memory of the minority game
C. H. Hung,S. S. Liaw
Physics , 2006, DOI: 10.1016/j.physa.2007.02.048
Abstract: It is known that the memory is relevant in the symmetric phase of the minority game. In our previous work we have successfully explained the quasi-periodic behavior of the game in the symmetric phase with the help of the probability theory. Based on this explanation, we are able to determine how the memory affects the variance of the system in this paper. By using some particular types of fake history such as periodic type and random type, we determine how efficient the memory has been used in the standard game. Furthermore, the analysis on the effective memory strongly supports the result we proposed previously that there are three distinct phases in the minority game.
An FBG-Based Impact Event Detection System for Structural Health Monitoring
C. S. Shin,B. L. Chen,S. K. Liaw
Advances in Civil Engineering , 2010, DOI: 10.1155/2010/253274
Abstract: Some structures are vulnerable to localized internal damages incurred by impact of small objects. An impact monitoring system using fiber Bragg grating (FBG) sensors has been established. Its ability to detect very low to medium energy impacts has been demonstrated on an aluminum plate and a 22?m long wind turbine blade. Previous analysis of this technique showed that the accuracy by which an impact position can be located is limited by equipment noises and angular insensitivity of the FBG. By employing two intensity demodulation schemes with different demodulation sensitivities and ranges, we try to differentiate the relative importance of the above limiting effects. Based on the results, directions for further improvement on impact source locating accuracy will be discussed and the implication of applying such systems on large-scale structures will be examined. 1. Introduction Impacts due to bird-strike and hailstorm may do much harm to structures such as aircraft and wind turbine blades. The structure will be especially vulnerable if it is made of polymeric composite as impacts may induce localized small internal damages. On actingupon byfluctuating service loading, these insidious defects may grow and eventuallylead to catastrophic failures. Although nondestructive examination techniques for the detection of internal damages are available, they are limited in resolution.Moreover, to stage a thorough examination over the entire structure can be highly time and resource consuming for a large-scale structure. The problem can be much alleviated if one knows where to look at and what to look for. The current work investigates the possibility of establishing an impact event monitoring system using fiber Bragg grating (FBG). FBG has found increasing applications as sensors in aerospace, structural, medical, and chemical applications for vibration, temperature, strain, impact, and general structural health monitoring [1–5]. It is chosen in the current task because of its good long-term durability and stability. In case of composite structures, optical fiber sensors possess the additional advantage of being compatible with common polymeric materials, making them easily embeddable inside a structure without inducing significant weakening of the material. Previous works on impact location identification mostly used piezoelectric sensors (e.g., [6, 7]). A three-sensor-based scheme was used to locate the impact position of a projectile on a target screen by measuring acoustic waves with microphones [8, 9]. However, this scheme requires a priori knowledge of the
Distance-two labelings of digraphs
G. J. Chang,J. -J. Chen,D. Kuo,S. C. Liaw
Mathematics , 2004,
Abstract: For positive integers $j\ge k$, an $L(j,k)$-labeling of a digraph $D$ is a function $f$ from $V(D)$ into the set of nonnegative integers such that $|f(x)-f(y)|\ge j$ if $x$ is adjacent to $y$ in $D$ and $|f(x)-f(y)|\ge k$ if $x$ is of distant two to $y$ in $D$. Elements of the image of $f$ are called labels. The $L(j,k)$-labeling problem is to determine the $\vec{\lambda}_{j,k}$-number $\vec{\lambda}_{j,k}(D)$ of a digraph $D$, which is the minimum of the maximum label used in an $L(j,k)$-labeling of $D$. This paper studies $\vec{\lambda}_{j,k}$- numbers of digraphs. In particular, we determine $\vec{\lambda}_{j,k}$- numbers of digraphs whose longest dipath is of length at most 2, and $\vec{\lambda}_{j,k}$-numbers of ditrees having dipaths of length 4. We also give bounds for $\vec{\lambda}_{j,k}$-numbers of bipartite digraphs whose longest dipath is of length 3. Finally, we present a linear-time algorithm for determining $\vec{\lambda}_{j,1}$-numbers of ditrees whose longest dipath is of length 3.
A Novel Route for the Inclusion of Metal Dopants in Silicon
Jules A. Gardener,Irving Liaw,Gabriel Aeppli,Ian W. Boyd,Richard J. Chater,Tim S. Jones,David S. McPhail,Gopinathan Sankar,A. Marshall Stoneham,Marcin Sikora,Geoff Thornton,Sandrine Heutz
Physics , 2010, DOI: 10.1088/0957-4484/21/2/025304
Abstract: We report a new method to introduce metal atoms into silicon wafers, using negligible thermal budget. Molecular thin films are irradiated with ultra-violet (UV) light releasing metal species into the semiconductor substrate. Secondary ion mass spectrometry (SIMS) and X-ray absorption spectroscopy (XAS) show that Mn is incorporated into Si as an interstitial dopant. We propose that our method can form the basis of a generic low-cost, low-temperature technology that could lead to the creation of ordered dopant arrays.
A Clinical Diagnostic Model for Predicting Influenza among Young Adult Military Personnel with Febrile Respiratory Illness in Singapore
Vernon J. Lee,Jonathan Yap,Alex R. Cook,Chi Hsien Tan,Jin-Phang Loh,Wee-Hong Koh,Elizabeth A. S. Lim,Jasper C. W. Liaw,Janet S. W. Chew,Iqbal Hossain,Ka Wei Chan,Pei-Jun Ting,Sock-Hoon Ng,Qiuhan Gao,Paul M. Kelly,Mark I. Chen,Paul A. Tambyah,Boon Huan Tan
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017468
Abstract: Influenza infections present with wide-ranging clinical features. We aim to compare the differences in presentation between influenza and non-influenza cases among those with febrile respiratory illness (FRI) to determine predictors of influenza infection.
Conductance for the two dimensional discrete random Schroedinger operator with small disorder
Constanze Liaw
Physics , 2012,
Abstract: As part of condensed-matter physics, the field of Anderson localization concerns the study of conductance of electrons in a random medium. We summarize and explain the results obtained in "A new numerical approach to Anderson (de)localization" from a physics perspective. Further, we discover a relationship with the so-called Thouless criterion - a dimensionless scaling parameter often used as the sole indicator whether or not the system exhibits Anderson localization.
Deterministic spectral properties of Anderson-type Hamiltonians
Constanze Liaw
Mathematics , 2010,
Abstract: This paper concerns the deterministic spectral properties of Anderson-type Hamiltonians. The main result states that under mild conditions the essential parts of two realizations are almost surely unitary equivalent modulo a rank one perturbation. Its proof is based on the techniques and results developed by A.G. Poltoratski in previous work.
A new numerical approach to Anderson (de)localization
Constanze Liaw
Mathematics , 2012, DOI: 10.1007/s10955-013-0879-5
Abstract: We develop a new approach for the Anderson localization problem. The implementation of this method yields strong numerical evidence leading to a (surprising to many) conjecture: The two dimensional discrete random Schroedinger operator with small disorder allows states that are dynamically delocalized with positive probability. This approach is based on a recent result by Abakumov-Liaw-Poltoratski which is rooted in the study of spectral behavior under rank-one perturbations, and states that every non-zero vector is almost surely cyclic for the singular part of the operator. The numerical work presented is rather simplistic compared to other numerical approaches in the field. Further, this method eliminates effects due to boundary conditions. While we carried out the numerical experiment almost exclusively in the case of the two dimensional discrete random Schroedinger operator, we include the setup for the general class of Anderson models called Anderson-type Hamiltonians. We track the location of the energy when a wave packet initially located at the origin is evolved according to the discrete random Schroedinger operator. This method does not provide new insight on the energy regimes for which diffusion occurs.
Rank one and finite rank perturbations - survey and open problems
Constanze Liaw
Mathematics , 2012,
Abstract: We survey the relationships of rank one self-adjoint and unitary perturbations as well as finite rank unitary perturbations with various branches of analysis and mathematical physics. We include the case of non-inner characteristic operator functions. For rank one perturbations and non-inner characteristic functions, we prove a representation formula for the adjoint of the Clark operator. Throughout we mention many open problems at varying levels of difficulty.
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