Dynamic Behavior of Precast Concrete Beam-Column Sub-Assemblages with High Performance Connections Subjected to Sudden Column Removal Scenario

Unbonded posttensioned precast concrete (UPPC) structure has shown its excellent aseismic performance in laboratory tests and earthquake investigation. However, the progressive collapse behavior of UPPC subjected to column removal scenario is still unclear. To fill this knowledge gap, two 1/2 scaled UPPC beam-column sub-assemblages were tested under a penultimate column removal scenario. The dynamic test results indicated that UPPC sub-assemblages have desirable load redistribution capacity to mitigate progressive collapse. The failure modes of the sub-assemblages observed in dynamic test were quite similar to that in static counterparts

Real space tests of the statistical isotropy and Gaussianity of the WMAP CMB data

ABRIDGED: We introduce and analyze a method for testing statistical isotropy and Gaussianity and apply it to the WMAP CMB foreground reduced, temperature maps, and cross-channel difference maps. We divide the sky into regions of varying size and shape and measure the first four moments of the one-point distribution within these regions, and using their simulated spatial distributions we test the statistical isotropy and Gaussianity hypotheses. By randomly varying orientations of these regions, we sample the underlying CMB field in a new manner, that offers a richer exploration of the data content, and avoids possible biasing due to a single choice of sky division. The statistical significance is assessed via comparison with realistic Monte-Carlo simulations. We find the three-year WMAP maps to agree well with the isotropic, Gaussian random field simulations as probed by regions corresponding to the angular scales ranging from 6 deg to 30 deg at 68% confidence level. We report a strong, anomalous (99.8% CL) dipole ``excess'' in the V band of the three-year WMAP data and also in the V band of the WMAP five-year data (99.3% CL). We notice the large scale hemispherical power asymmetry, and find that it is not highly statistically significant in the WMAP three-year data (<~ 97%) at scales l <= 40. The significance is even smaller if multipoles up to l=1024 are considered (~90% CL). We give constraints on the amplitude of the previously-proposed CMB dipole modulation field parameter. We easily detect the residual foregrounds in cross-band difference maps at rms level <~ 7 \mu K (at scales >~ 6 deg) and limit the systematical uncertainties to <~ 1.7 \mu K (at scales >~ 30 deg).Comment: 20 pages, 20 figures; more tests added; updated to match the version to be published in JCA

Asymmetrical domain wall propagation in bifurcated PMA wire structure due to the Dzyaloshinskii-Moriya interaction

Controlling domain wall (DW) motion in complex magnetic network structures is of paramount significance for the development of spin-based devices. Here, we report on the dynamics of a propagating DW in a bifurcated ferromagnetic wire with perpendicular magnetic anisotropy (PMA). The Dzyaloshinskii-Moriya interaction (DMI) in the wire structure induces a tilt angle to the injected DW, which leads to a quasi-selective propagation through the network branch. The DW tilting causes a field interval between DWs to arrive at Hall bars in the individual branches. Micromagnetic results further show that by tailoring the strength of the DMI, the control of DW dynamics in the PMA complex network structures can be achieved

A CASE STUDY OF ENGINEERING ETHICS: LESSON LEARNED FROM BUILDING COLLAPSE DISASTER TOWARD MALAYSIAN ENGINEERS

This paper presents the case study on the Hotel New World tragedy. The building collapsed on 15th March 1986 and an investigation was conducted to determine the main cause of this tragedy. There were several speculations made on the cause of the collapse such as internal explosion, bad concrete mixture and swampy land affecting the building’s foundations. However, after thorough investigations, these speculations were proved to be inappropriate and the main cause was found to be due to the engineer’s miscalculation during the designing stage which leads to this catastrophic failure of the building. Rescue operation was initiated immediately after the collapse to rescue the victims and the aftermath of this tragedy had led to multiple reclamations. These reclamations include the endorsement of Building Control Act 1989 along Building Control (Accredited Checkers) Regulations 1989 as a stricter quality control measure. The analysis shows that this case may be due to unwanted mistakes or negligence of the engineers in carrying out their duties. Several actions were taken according to the ethical theories and codes of ethics. However after the analysis and evaluation were done, duty ethics and right ethics were more relevant to the collapse of Hotel New World case as compared to the other ethical theories and thus reclamations were done based on duty ethics and right ethic

A CASE STUDY OF ENGINEERING ETHICS: LESSON LEARNED FROM BUILDING COLLAPSE DISASTER TOWARD MALAYSIAN ENGINEERS

This paper presents the case study on the Hotel New World tragedy. The building collapsed on 15th March 1986 and an investigation was conducted to determine the main cause of this tragedy. There were several speculations made on the cause of the collapse such as internal explosion, bad concrete mixture and swampy land affecting the building’s foundations. However, after thorough investigations, these speculations were proved to be inappropriate and the main cause was found to be due to the engineer’s miscalculation during the designing stage which leads to this catastrophic failure of the building. Rescue operation was initiated immediately after the collapse to rescue the victims and the aftermath of this tragedy had led to multiple reclamations. These reclamations include the endorsement of Building Control Act 1989 along Building Control (Accredited Checkers) Regulations 1989 as a stricter quality control measure. The analysis shows that this case may be due to unwanted mistakes or negligence of the engineers in carrying out their duties. Several actions were taken according to the ethical theories and codes of ethics. However after the analysis and evaluation were done, duty ethics and right ethics were more relevant to the collapse of Hotel New World case as compared to the other ethical theories and thus reclamations were done based on duty ethics and right ethic

A CASE STUDY OF ENGINEERING ETHICS: LESSON LEARNED FROM BUILDING COLLAPSE DISASTER TOWARD MALAYSIAN ENGINEERS

This paper presents the case study on the Hotel New World tragedy. The building collapsed on 15th March 1986 and an investigation was conducted to determine the main cause of this tragedy. There were several speculations made on the cause of the collapse such as internal explosion, bad concrete mixture and swampy land affecting the building’s foundations. However, after thorough investigations, these speculations were proved to be inappropriate and the main cause was found to be due to the engineer’s miscalculation during the designing stage which leads to this catastrophic failure of the building. Rescue operation was initiated immediately after the collapse to rescue the victims and the aftermath of this tragedy had led to multiple reclamations. These reclamations include the endorsement of Building Control Act 1989 along Building Control (Accredited Checkers) Regulations 1989 as a stricter quality control measure. The analysis shows that this case may be due to unwanted mistakes or negligence of the engineers in carrying out their duties. Several actions were taken according to the ethical theories and codes of ethics. However after the analysis and evaluation were done, duty ethics and right ethics were more relevant to the collapse of Hotel New World case as compared to the other ethical theories and thus reclamations were done based on duty ethics and right ethic

Model for a Light Z' Boson

A model of a light $Z'$ boson is constructed and phenomenological bounds are derived. This $Z'$ boson arises from a very simple extension to the Standard Model, and it is constrained to be light because the vacuum expectation values which generate its mass also break the electroweak gauge group. It is difficult to detect experimentally because it couples exclusively or primarily (depending on symmetry breaking details) to second and third generation leptons. However, if the $Z'$ boson is sufficiently light, then there exists the possibility of the two-body decay $\tau \rightarrow \mu Z'$ occuring. This will provide a striking signature to test the model.Comment: 20 pages + 5 pages of figures (appended as postscipt files), LaTeX, OITS-53

Hemispherical power asymmetry: parameter estimation from CMB WMAP5 data

We reexamine the evidence of the hemispherical power asymmetry, detected in the CMB WMAP data using a new method. At first, we analyze the hemispherical variance ratios and compare these with simulated distributions. Secondly, working within a previously-proposed CMB bipolar modulation model, we constrain model parameters: the amplitude and the orientation of the modulation field as a function of various multipole bins. Finally, we select three ranges of multipoles leading to the most anomalous signals, and we process corresponding 100 Gaussian, random field (GRF) simulations, treated as observational data, to further test the statistical significance and robustness of the hemispherical power asymmetry. For our analysis we use the Internally-Linearly-Coadded (ILC) full sky map, and KQ75 cut-sky V channel, foregrounds reduced map of the WMAP five year data (V5). We constrain the modulation parameters using a generic maximum a posteriori method. In particular, we find differences in hemispherical power distribution, which when described in terms of a model with bipolar modulation field, exclude the field amplitude value of the isotropic model A=0 at confidence level of ~99.5% (~99.4%) in the multipole range l=[7,19] (l=[7,79]) in the V5 data, and at the confidence level ~99.9% in the multipole range l=[7,39] in the ILC5 data, with the best fit (modal PDF) values in these particular multipole ranges of A=0.21 (A=0.21) and A=0.15 respectively. However, we also point out that similar or larger significances (in terms of rejecting the isotropic model), and large best-fit modulation amplitudes are obtained in GRF simulations as well, which reduces the overall significance of the CMB power asymmetry down to only about 94% (95%) in the V5 data, in the range l=[7,19] (l=[7,79]).Comment: 24 pages, 10 figures; few typos corrected; published in JCA

Effect of pre-existing baryon inhomogeneities on the dynamics of quark-hadron transition

Baryon number inhomogeneities may be generated during the epoch when the baryon asymmetry of the universe is produced, e.g. at the electroweak phase transition. The regions with excess baryon number will have a lower temperature than the background temperature of the universe. Also the value of the quark hadron transition temperature $T_c$ will be different in these regions as compared to the background region. Since a first-order quark hadron transition is very susceptible to small changes in temperature, we investigate the effect of the presence of such baryonic lumps on the dynamics of quark-hadron transition. We find that the phase transition is delayed in these lumps for significant overdensities. Consequently, we argue that baryon concentration in these regions grows by the end of the transition. We briefly discuss some models which may give rise to such high overdensities at the onset of the quark-hadron transition.Comment: 16 pages, no figures, minor changes, version to appear in Phys. Rev.