Controllable vacuum-induced diffraction of matter-wave superradiance using an all-optical dispersive cavity

Cavity quantum electrodynamics (CQED) has played a central role in demonstrating the fundamental principles of the quantum world, and in particular those of atom-light interactions. Developing fast, dynamical and non-mechanical control over a CQED system is particularly desirable for controlling atomic dynamics and building future quantum networks at high speed. However conventional mirrors do not allow for such flexible and fast controls over their coupling to intracavity atoms mediated by photons. Here we theoretically investigate a novel all-optical CQED system composed of a binary Bose-Einstein condensate (BEC) sandwiched by two atomic ensembles. The highly tunable atomic dispersion of the CQED system enables the medium to act as a versatile, all-optically controlled atomic mirror that can be employed to manipulate the vacuum-induced diffraction of matter-wave superradiance. Our study illustrates a innovative all-optical element of atomtroics and sheds new light on controlling light-matter interactions

Lighting Analysis at Access Zone of Tunnel Entrance of Hong Kong-Zuhai-Macao Bridge (HZMB)

The study aimed to evaluate several shading schemes at access zone of the tunnel entrance of HZMB in order to find the best scenario to increase the user lighting comfort. The study analysed the luminance at the tunnel entrance (L20) and energy saving in the thereshold zone. For these analyses, four shading schemes have been simulated. The schemes were the Original Scheme (Zebra, 50% solid & 50% transparent), Option 1 (Gradation Glass), Option 2 (Perforated Material), and Option 3 (No Shading). The results shows that the Original scheme has the lowest L20 luminance and consequently the highest lighting energy saving. While the Option 3 (No Shading) has the highest L20 luminance and consequently the lowest lighting energy saving

Quaternion-valued single-phase model for three-phase power system

In this work, a quaternion-valued model is proposed in lieu of the Clarke's α, β transformation to convert three-phase quantities to a hypercomplex single-phase signal. The concatenated signal can be used for harmonic distortion detection in three-phase power systems. In particular, the proposed model maps all the harmonic frequencies into frequencies in the quaternion domain, while the Clarke's transformation-based methods will fail to detect the zero sequence voltages. Based on the quaternion-valued model, the Fourier transform, the minimum variance distortionless response (MVDR) algorithm and the multiple signal classification (MUSIC) algorithm are presented as examples to detect harmonic distortion. Simulations are provided to demonstrate the potentials of this new modeling method

Modeling GRB 050904: Autopsy of a Massive Stellar Explosion at z=6.29

GRB 050904 at redshift z=6.29, discovered and observed by Swift and with spectroscopic redshift from the Subaru telescope, is the first gamma-ray burst to be identified from beyond the epoch of reionization. Since the progenitors of long gamma-ray bursts have been identified as massive stars, this event offers a unique opportunity to investigate star formation environments at this epoch. Apart from its record redshift, the burst is remarkable in two respects: first, it exhibits fast-evolving X-ray and optical flares that peak simultaneously at t~470 s in the observer frame, and may thus originate in the same emission region; and second, its afterglow exhibits an accelerated decay in the near-infrared (NIR) from t~10^4 s to t~3 10^4 s after the burst, coincident with repeated and energetic X-ray flaring activity. We make a complete analysis of available X-ray, NIR, and radio observations, utilizing afterglow models that incorporate a range of physical effects not previously considered for this or any other GRB afterglow, and quantifying our model uncertainties in detail via Markov Chain Monte Carlo analysis. In the process, we explore the possibility that the early optical and X-ray flare is due to synchrotron and inverse Compton emission from the reverse shock regions of the outflow. We suggest that the period of accelerated decay in the NIR may be due to suppression of synchrotron radiation by inverse Compton interaction of X-ray flare photons with electrons in the forward shock; a subsequent interval of slow decay would then be due to a progressive decline in this suppression. The range of acceptable models demonstrates that the kinetic energy and circumburst density of GRB 050904 are well above the typical values found for low-redshift GRBs.Comment: 45 pages, 7 figures, and ApJ accepted. Revised version, minor modifications and 1 extra figur

Thermal Performance of Naturally Ventilated Classroom in the Faculty of Engineering Hasanuddin University, Gowa Campus

This study aims to identify the thermal performance of naturally ventilated classrooms of the new campus of Faculty of Engineering, Hasanuddin University in Gowa. The natural ventilation system has three main functions that are to provide healthy air for occupants, to provide thermal comfort to the occupants, and to cool the fabrics in the building interior. Thermal comfort perceived by the user is determined by many factors, including physical, psychological, etc. This research was conducted by using the experimental method with research analysis using CFD (Computational Fluid Dynamics) simulation method. The input parameters in the simulation were obtained through field measurement in the form of room dimension, ventilation open area, and microclimate parameter. The simulation is carried out at maximum open conditions in existing ventilation system with open and closed class door treatment. The simulation treatment of airflow input speeds were 0.25, 0.5, 0.75, and 1 m/s. The results showed that the existing ventilation system of Classroom at Faculty of Engineering (FoE) Hasanuddin University (Unhas) with an opening ratio of 16.59 to 22.76% of the floor area is good enough to flow and distribute comfortable air movement inside the classroom, especially at airflow speeds above 0.5 m/s

Influence of temperature, light and plant growth regulators on germination of black pepper (Piper nigrum L.) seeds

Effects of temperature, light and different concentrations of plant growth regulators on germination of Piper nigrum L. seeds was studied under controlled environmental conditions. Black pepper seeds were placed inPetri dishes with filtration papers and the germination and radical  development followed during eighteen days periods. The seeds generally germinated within six or seven days. There was no difference in percentgermination between dark and light treatments, but the development of radical length was significantly influenced by both light and temperature. Germination was highest at 30°C, but seeds also germinated at 25and 35°C. No germination was observed at low (20°C) and high (40 and 45°C) temperatures. The plant growth regulators enhanced the seeds germination and radical length different degree. The results are consistent with the Piper nigrum L. being recalcitrant species need a certain environment condition to germinate

Three-Dimensional Wind Profile Prediction with Trinion-Valued Adaptive Algorithms

The problem of three-dimensional (3-D) wind profile prediction is addressed based a trinion wind model, which inherently reckons the coupling of the three perpendicular components of a wind field. The augmented trinion statistics are developed and employed to enhance the prediction performance due to its full exploitation of the second-order statistics. The proposed trinion domain processing can be regarded as a more compact version of the existing quaternion-valued approach, with a lower computational complexity. Simulations based on recorded wind data are provided to demonstrate the effectiveness of the proposed methods