Fracture morphology and its evolution A review on crack path stability and brittle fracture along butt-weld

Considerations are made for the fracture morphology and its evolution in relation to the brittle fracture along butt-weld, where crack path stability may play important roles in various aspects. Analyses of a kinked and curved crack are first reviewed in the present paper. Having learned the solutions of a kinked and curved crack, several crack path criteria are compared for the crack path prediction. Then, some aspects of stability of a crack path are examined as to whether it may propagate, keeping its original direction or not in a homogeneous material, and whether crack kinking in a material having inhomogeneous fracture toughness may be predicted by seeking the state which gives rise to an energetically stable one. Having reviewed the morphology of brittle crack propagation along butt-weld, brittle fracture of extremely thick plates of high tensile steel is discussed for the fracture control of recently emerging large container ships.&nbsp

Resource Configuration and Network Design in Extensible Networks

The goal of packet-switched networks has conventionally been delivering data to users. This concept is changing rapidly as current technologies make it possible to build network processing engines that apply intermediary services to data traffic. This trend introduces an extensive range of ways to develop and operate applications by allowing processing services customized for applications\u27 needs at intermediate network users, as it can relieve individuals from the need to acquire, install, and maintain software in end systems to perform required functions. As such network services become more widely used, it will become increasingly important for service providers to have effective methods to configure applications sessions so that they use resources efficiently. On the other hand, it is equally important to design such extensible networks properly in order to ensure desirable performance of applications. This dissertation addresses these two key problems that arise in operation and provisioning extensible networks: configuring application sessions and designing extensible networks. First, we present a general method, called layered networks, for the problem of configuring application sessions that require intermediate processing. The layered network method finds optimal configurations by transforming the session configuration problem into conventional shortest path problem. We show, through a series of examples, that the method can be applied to a wide variety of situations. We also discuss how to configure applications that require reserved capacity and propose effective heuristic algorithms that are based on the layered network method. Second, for designing extensible networks, we generalize the constraint-based network design methods originally developed for conventional networks. We show how to incorporate arbitrary requirements that are allowed by extensible networks in a flexible and general way. We also show how to extend the original framework to dimension both processing resources and link bandwidth. These results have been incorporated into software packaged the Extensible Network Planner (XNP)

Circadian patterns of Wikipedia editorial activity: A demographic analysis

Wikipedia (WP) as a collaborative, dynamical system of humans is an appropriate subject of social studies. Each single action of the members of this society, i.e. editors, is well recorded and accessible. Using the cumulative data of 34 Wikipedias in different languages, we try to characterize and find the universalities and differences in temporal activity patterns of editors. Based on this data, we estimate the geographical distribution of editors for each WP in the globe. Furthermore we also clarify the differences among different groups of WPs, which originate in the variance of cultural and social features of the communities of editors

A Start-Timing Detector for the Collider Experiment PHENIX at RHIC-BNL

We describe a start-timing detector for the PHENIX experiment at the relativistic heavy-ion collider RHIC. The role of the detector is to detect a nuclear collision, provide precise time information with an accuracy of 50ps, and determine the collision point along the beam direction with a resolution of a few cm. Technical challenges are that the detector must be operational in a wide particle-multiplicity range in a high radiation environment and a strong magnetic field. We present the performance of the prototype and discuss the final design of the detector.Comment: 12 pages, LaTeX, 9 gif and 4 ps figures. Submitted to NIM

Modelling of ultrasonic impact treatment (UIT) of welded joints and its effect on fatigue strength

Ultrasonic impact treatment (UIT) is a remarkable post-weld technique applying mechanical impacts in combination with ultrasound into the welded joints. In the present work, a 3D simulation method including welding simulation, numerical modelling of UIT-process and an evaluation of fatigue crack growth has been developed. In the FE model, the actual treatment conditions and local mechanical characteristics due to acoustic softening are set as input parameters. The plastic deformation and compressive stress layer are found to be more pronounced when acoustic softening takes place. The predicted internal residual stress distributions of welded joint before and after UIT are compared with experimental results, showing a fairly good agreement with each other. Finally, simulated results of fatigue crack growth in various residual stress fields are well compared with test results, so that the proposed model may provide an effective tool to simulate UIT-process in engineering structures

Peningkatan Kepercayaan Diri Mahasiswa melalui Pelatihan Asertivitas

This study was initiated by the observation that Brawijaya University psychology student batch 2007 and 2008 appeared passive in the teaching-learning process. It is acknowledged that an assertive training will be needed. The training is expected to be a pilot project or the initial steps for the implementation of students' soft skills.This study aims to determine the effectiveness of assertive training to enhance student confidence. Subjects of 22 psychology students will be examined through experimental repeated measure design methodSelf confidence level was measured twice pre and post the training given. Based on the t-test test results of the self confidence level rates obtained from the pre test mean of 103.68 with standard deviations of 7.17. While the post test came up with mean of 122.45 with standard deviations of 10.05. The results of the research showed that the confidence scores of students increased significantly after the training is given. This conclusion showed that assertive training was effective to improve confidence level of the students

Bandwidth-Controlled Insulator-Metal Transition and Correlated Metallic State in 5dd Transition Metal Oxides Srn+1_{n+1}Irn_{n}O3n+1_{3n+1} (nn=1, 2, and ∞\infty)

We investigated the electronic structures of the 5$d$ Ruddlesden-Popper series Sr$_{n+1}$Ir$_{n}$O$_{3n+1}$ ($n$=1, 2, and $\infty$) using optical spectroscopy and first-principles calculations. As 5$d$ orbitals are spatially more extended than 3$d$ or 4$d$ orbitals, it has been widely accepted that correlation effects are minimal in 5$d$ compounds. However, we observed a bandwidth-controlled transition from a Mott insulator to a metal as we increased $n$. In addition, the artificially synthesized perovskite SrIrO$_{3}$ showed a very large mass enhancement of about 6, indicating that it was in a correlated metallic state

Source blending effects on microlensing time-histograms and optical depth determination

Source blending in microlensing experiments is known to modify the Einstein time of the observed events. In this paper, we have conducted Monte-Carlo calculations, using the analytical relationships derived by Han (1999) to quantify the effect of blending on the observed event time distribution and optical depth. We show that short-time events are affected significantly by source blending and that, for moderately blended sources, the optical depth $\tau$ is globally overestimated, because of an underestimation of the exposure. For high blending situations, on the opposite, blending leads to an {\it under}estimation of the optical depth. Our results are in agreement with the most recent optical depth determinations toward the Galactic Center of the MACHO collaboration (Popowski et al. 2004) and the OGLE-II collaboration (Sumi et al. 2005) that use clump giants (less affected by the blending effect) as sources. The blending-corrected, lower optical depth toward the Galactic Bulge is now in good agreement with the value inferred from galactic models, reconciling theoretical and observational determinations.Comment: Accepted in Astronomy Astrophysics. Note that these calculations were conducted in 2001, prior to the recent DIA analyses mentioned in the references (see Alibert, Y. SF2A-conference, 2001

Exact treatment of exciton-polaron formation by Diagrammatic Monte Carlo

We develop an approximation-free Diagrammatic Monte Carlo technique to study fermionic particles interacting with each other simultaneously through both an attractive Coulomb potential and bosonic excitations of the underlying medium. Exemplarily we apply the method to the long-standing exciton-polaron problem and present numerically exact results for the wave function, ground-state energy, binding energy and effective mass of this quasiparticle. Focusing on the electron-hole pair bound-state formation, we discuss various limiting cases of a generic exciton-polaron model. The frequently used instantaneous approximation to the retarded interaction due to the phonon exchange is found to be of very limited applicability. For the case of a light electron and heavy hole the system is well approximated by a particle in the field of a static attractive impurity.Comment: 5 pages, 5 figure