Very Fast Chip-level Thermal Analysis

We present a new technique of VLSI chip-level thermal analysis. We extend a newly developed method of solving two dimensional Laplace equations to thermal analysis of four adjacent materials on a mother board. We implement our technique in C and compare its performance to that of a commercial CAD tool. Our experimental results show that our program runs 5.8 and 8.9 times faster while keeping smaller residuals by 5 and 1 order of magnitude, respectively.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Position measurements of rapidly fluctuating microwave bursts

It was investigated whether microwave source positions change while the total fluxes of hard X-rays and microwaves show remarkable rapid fluctuations of the order of seconds. The position measurements were made in one dimension (east-west direction) with the 17 GHz interferometer at Nobeyama. Position changes greater than a few arc seconds can be detected. The result shows that significant position changes are found for five of seven bursts but that no position changes greater than 3 arc seconds are found for the remaining two bursts

Thermodynamic Construction of an One-Step Replica-Symmetry-Breaking Solution in Finite Connectivity Spin Glasses

An one-step replica-symmetry-breaking solution for finite connectivity spin-glass models with K body interaction is constructed at finite temperature using the replica method and thermodynamic constraints. In the absence of external fields, this construction provides a general extension of replica symmetric solution at finite replica number to one-step replica-symmetry-breaking solution. It is found that this result is formally equivalent to that of the one-step replica-symmetry-breaking cavity method. To confirm the validity of the obtained solution, Monte Carlo simulations are performed for K = 2 and 3. The thermodynamic quantities of the Monte Carlo results extrapolated to a large-size limit are consistent with those estimated by our solution for K = 2 at all simulated temperatures and for K = 3 except near the transition temperature.Comment: 11pages, 19 figures. Added content and references. Accepted to Phys. Rev.

A Systematic Study of X-Ray Flares from Low-Mass Young Stellar Objects in the Rho Ophiuchi Star-Forming Region with Chandra

We report on the results of a systematic study of X-ray flares from low-mass young stellar objects, using Chandra observations of the main region of the Rho Oph. From 195 X-ray sources, including class I-III sources and some young brown dwarfs, we detected a total of 71 X-ray flares. Most of the flares have the typical profile of solar and stellar flares, fast rise and slow decay. We derived the time-averaged temperature (kT), luminosity (L_X), rise and decay timescales (tau_r and tau_d) of the flares, finding that (1) class I-II sources tend to have a high kT, (2) the distribution of L_X during flares is nearly the same for all classes, and (3) positive and negative log-linear correlations are found between tau_r and tau_d, and kT and tau_r. In order to explain these relations, we used the framework of magnetic reconnection model to formulate the observational parameters as a function of the half-length of the reconnected magnetic loop (L) and magnetic field strength (B). The estimated L is comparable to the typical stellar radius of these objects (10^{10-11} cm), which indicates that the observed flares are triggered by solar-type loops, rather than larger ones (10^{12} cm) connecting the star with its inner accretion disk. The higher kT observed for class I sources may be explained by a higher magnetic field strength (about 500 G) than for class II-III sources (200-300 G).Comment: 33 pages, 7 figures, accepted for publication in PASJ, the complete version of tables are available at ftp://ftp-cr.scphys.kyoto-u.ac.jp/pub/crmember/kensuke/PASJ_RhoOph/KI_all.tar .g

High-Energy Spin Dynamics in La1.69_{1.69}Sr0.31_{0.31}NiO4_4

We have mapped out the spin dynamics in a stripe-ordered nickelate, La$_{2-x}$Sr$_{x}$NiO$_{4}$ with $x \simeq 0.31$, using inelastic neutron scattering. We observe spin-wave excitations up to 80 meV emerging from the incommensurate magnetic peaks with an almost isotropic spin-velocity: $\hbar c_s\sim 0.32$ eV \AA, very similar to the velocity in the undoped, insulating parent compound, La$_{2}$NiO$_{4}$. We also discuss the similarities and differences of the inferred spin-excitation spectrum with those reported in superconducting high-$T_c$ cuprates.Comment: 4 figure

Combinatorial realizations of crystals via torus actions on quiver varieties

Consider Kashiwara's crystal associated to a highest weight representation of a symmetric Kac-Moody algebra. There is a geometric realization of this object using Nakajima's quiver varieties, but in many particular cases it can also be realized by elementary combinatorial methods. Here we propose a framework for extracting combinatorial realizations from the geometric picture: We construct certain torus actions on the quiver varieties and use Morse theory to index the irreducible components by connected components of the subvariety of torus fixed points. We then discuss the case of affine sl(n). There the fixed point components are just points, and are naturally indexed by multi-partitions. There is some choice in our construction, leading to a family of combinatorial models for each highest weight crystal. Applying this construction to the crystal of the fundamental representation recovers a family of combinatorial realizations recently constructed by Fayers. This gives a more conceptual proof of Fayers' result as well as a generalization to higher level. We also discuss a relationship with Nakajima's monomial crystal.Comment: 23 pages, v2: added Section 8 on monomial crystals and some references; v3: many small correction

Investigation of Visual Management Cases in Construction by an Analytical Framework from Manufacturing

Along with the progress of globalization, speed and efficiency have become more critical for any industry than ever before. In this sense, the concept and methods of lean management, promoting these performances, have been deployed from manufacturing, its origin industry, to other industries. This paper deals with this management style in the construction industry, called lean construction. In particular, visual management (VM) as one effective tool in this scheme is focused on. A number of VM cases, 306 in total, was collected from both construction and manufacturing sites and investigated by the so-called 5W1H analytical framework developed in the manufacturing industry. Obtained results suggest that the VM cases in construction have common attributes such as purpose and location, target to attain, users’ attributes, timing to use and elemental technologies for case development. A comparison analysis of the VM cases from construction and those from manufacturing was also carried out, for a mutual transfer of this technology between these industries

An Approach to N=4{\cal N}=4 ADE Gauge Theory on K3

We propose a recipe for determination of the partition function of ${\cal N}=4$ $ADE$ gauge theory on $K3$ by generalizing our previous results of the SU(N) case. The resulting partition function satisfies Montonen-Olive duality for $ADE$ gauge group.Comment: 28 pages, Latex, enlarged published versio