High-speed measurement of rotational anisotropy nonlinear optical harmonic generation using position sensitive detection

We present a method of performing high-speed rotational anisotropy nonlinear optical harmonic generation experiments at rotational frequencies of several hertz by projecting the harmonic light reflected at different angles from a sample onto a stationary position sensitive detector. The high rotational speed of the technique, $10^3$ to $10^4$ times larger than existing methods, permits precise measurements of the crystallographic and electronic symmetries of samples by averaging over low frequency laser power, beam pointing, and pulse width fluctuations. We demonstrate the sensitivity of our technique by resolving the bulk four-fold rotational symmetry of GaAs about its [001] axis using second harmonic generation

β\beta-decay half-lives of neutron-rich nuclei and matter flow in the rr-process

The $\beta$-decay half-lives of neutron-rich nuclei with $20 \leqslant Z \leqslant 50$ are systematically investigated using the newly developed fully self-consistent proton-neutron quasiparticle random phase approximation (QRPA), based on the spherical relativistic Hartree-Fock-Bogoliubov (RHFB) framework. Available data are reproduced by including an isospin-dependent proton-neutron pairing interaction in the isoscalar channel of the RHFB+QRPA model. With the calculated $\beta$-decay half-lives of neutron-rich nuclei a remarkable speeding up of $r$-matter flow is predicted. This leads to enhanced $r$-process abundances of elements with $A \gtrsim 140$, an important result for the understanding of the origin of heavy elements in the universe.Comment: 14 pages, 4 figure

Stability of Strutinsky Shell Correction Energy in Relativistic Mean Field Theory

The single-particle spectrum obtained from the relativistic mean field (RMF) theory is used to extract the shell correction energy with the Strutinsky method. Considering the delicate balance between the plateau condition in the Strutinsky smoothing procedure and the convergence for the total binding energy, the proper space sizes used in solving the RMF equations are investigated in detail by taking 208Pb as an example. With the proper space sizes, almost the same shell correction energies are obtained by solving the RMF equations either on basis space or in coordinate space.Comment: 9 pages, 4 figure

The application scenarios of smart construction objects (SCOs) in construction

The primary aim of this study is to investigate the application scenarios of smart construction objects (SCOs). SCOs are construction resources (e.g. machinery, device, and materials) that are made “smart” by augmenting them with technologies conferring autonomy, awareness, and the ability to interact with their vicinity. The research starts from a brief review of recent developments of smart technology in different industrial sectors including construction. Based on the definition and properties of SCOs, interviews and site visits are conducted to investigate how SCOs could be applied under different scenarios of the construction industry. Perspectives for future studies are proposed in order to fully realise their potentials. The research encourages a wider adoption of SCOs and smart technologies in improving current construction practices. It also provides academia with a platform for further exploring the innovative uses of SCOs in constructionpostprin

Spin and orbital moments of ultra-thin Fe films on various semiconductor surfaces

The magnetic moments of ultrathin Fe films on three different III-V semiconductor substrates, namely GaAs, InAs and In0.2Ga0.8As have been measured with X-ray magnetic circular dichroism at room temperature to assess their relative merits as combinations suitable for next-generation spintronic devices. The results revealed rather similar spin moments and orbital moments for the three systems, suggesting the relationship between film and semiconductor lattice parameters to be less critical to magnetic moments than magnetic anisotropy

Separable states and the geometric phases of an interacting two-spin system

It is known that an interacting bipartite system evolves as an entangled state in general, even if it is initially in a separable state. Due to the entanglement of the state, the geometric phase of the system is not equal to the sum of the geometric phases of its two subsystems. However, there may exist a set of states in which the nonlocal interaction does not affect the separability of the states, and the geometric phase of the bipartite system is then always equal to the sum of the geometric phases of its subsystems. In this paper, we illustrate this point by investigating a well known physical model. We give a necessary and sufficient condition in which a separable state remains separable so that the geometric phase of the system is always equal to the sum of the geometric phases of its subsystems.Comment: 13 page

The CO A-X System for Constraining Cosmological Drift of the Proton-Electron Mass Ratio

The $\textrm{A}^1\Pi-\textrm{X}^1\Sigma^+$ band system of carbon monoxide, which has been detected in six highly redshifted galaxies ($z=1.6-2.7$), is identified as a novel probe method to search for possible variations of the proton-electron mass ratio ($\mu$) on cosmological time scales. Laboratory wavelengths of the spectral lines of the A-X ($v$,0) bands for $v=0-9$ have been determined at an accuracy of $\Delta\lambda/\lambda=1.5 \times 10^{-7}$ through VUV Fourier-transform absorption spectroscopy, providing a comprehensive and accurate zero-redshift data set. For the (0,0) and (1,0) bands, two-photon Doppler-free laser spectroscopy has been applied at the $3 \times 10^{-8}$ accuracy level, verifying the absorption data. Sensitivity coefficients $K_{\mu}$ for a varying $\mu$ have been calculated for the CO A-X bands, so that an operational method results to search for $\mu$-variation.Comment: 7 pages (main article), 3 figures, includes supplementary materia

Failure Probabilities and Tough-Brittle Crossover of Heterogeneous Materials with Continuous Disorder

The failure probabilities or the strength distributions of heterogeneous 1D systems with continuous local strength distribution and local load sharing have been studied using a simple, exact, recursive method. The fracture behavior depends on the local bond-strength distribution, the system size, and the applied stress, and crossovers occur as system size or stress changes. In the brittle region, systems with continuous disorders have a failure probability of the modified-Gumbel form, similar to that for systems with percolation disorder. The modified-Gumbel form is of special significance in weak-stress situations. This new recursive method has also been generalized to calculate exactly the failure probabilities under various boundary conditions, thereby illustrating the important effect of surfaces in the fracture process.Comment: 9 pages, revtex, 7 figure

An SCO-enabled logistics and supply-chain management system in construction

Logistic and supply chain management (LSCM) is of paramount importance to a construction project but is often problematic. Many researchers see LSCM per se as a web of decisions to be made, and attribute problems to a lack of process and information concurrence. This is exacerbated by fragmentation, discontinuity, and heterogeneity in construction LSCM. The bi-directional information flow remains unachieved in the existing sensing-based systems for construction LSCM. Without panoramically interconnected to other smart abilities such as the automatic action-taking ability, most existing sensing-based systems are insufficient to realize their full potentials in facilitating construction LSCM. Building on previous studies on smart construction objects (SCOs), this paper aims to develop an SCO-enabled system that can enhance concurrence of process and information, with a view to informing better decision-making in construction LSCM. It does so by first analyzing the problems in prevailing LSCM practices using business process reengineering. Based on this analysis, the architecture for an SCO-enabled LSCM system is proposed and developed into a prototype. Then the system is calibrated and validated in the rich context of offshore prefabrication housing production in Hong Kong. It is found that SCOs, with their properties of awareness, communicativeness, and autonomy built into a smart management system, can supplement the existing LSCM process with more concurrent decision-making information. This paper contributes to the body of knowledge in two areas. It adds to the theoretical debate on decision-making by arguing the importance of information and process concurrence and trying to explicate it in the context of construction LSCM. In addition, the SCO-enabled LSCM system can be implemented in real-life practice to alleviate the many problems existing in construction LSCM.postprin