Characteristics of profiles of gamma-ray burst pulses associated with the Doppler effect of fireballs

In this paper, we derive in a much detail the formula of count rates, in terms of the integral of time, of gamma-ray bursts in the framework of fireballs, where the Doppler effect of the expanding fireball surface is the key factor to be concerned. Effects arising from the limit of the time delay due to the limited regions of the emitting areas in the fireball surface and other factors are investigated. Our analysis shows that the formula of the count rate of fireballs can be expressed as a function of $\tau$ which is the observation time scale relative to the dynamical time scale of the fireball. The profile of light curves of fireballs depends only on the relative time scale, entirely independent of the real time scale and the real size of the objects. It displays in detail how a cutoff tail, or a turn over, feature (called a cutoff tail problem) in the decay phase of a light curve can be formed. This feature is a consequence of a hot spot in the fireball surface, moving towards the observer, and was observed in a few cases previously. By performing fits to the count rate light curves of six sample sources, we show how to obtain some physical parameters from the observed profile of the count rate of GRBs. In addition, the analysis reveals that the Doppler effect of fireballs could lead to a power law relationship between the $FWHM$ of pulses and energy, which were observed previously by many authors.Comment: 38 pages, 10 figures; accepted for publication in ApJ (10 December 2004, v617

Light Wave Propagation and Scattering Through Particles

The study of light propagating and scattering for various particles has always been important in many practical applications, such as optical diagnostics for combustion, monitoring of atmospheric pollution, analysis of the structure and pathological changes of the biological cell, laser Doppler technology, and so on. This chapter discusses propagation and scattering through particles. The description of the solution methods, numerical results, and potential application of the light scattering by typical particles is introduced. The generalized Lorenz-Mie theory (GLMT) for solving the problem of Gaussian laser beam scattering by typical particles with regular shapes, including spherical particles, spheroidal particles, and cylindrical particles, is described. The numerical methods for the scattering of Gaussian laser beam by complex particles with arbitrarily shape and structure, as well as random discrete particles are introduced. The essential formulations of numerical methods are outlined, and the numerical results for some complex particles are also presented

(2E,5E)-2,5-Bis(3,4,5-trimethoxy­benzyl­idene)cyclo­penta­none

The title compound, C25H28O7, was prepared by the base-catalysed reaction of 3,4,5-trimethoxy­benzaldehyde with cyclo­penta­none. The mol­ecule has crystallographic twofold rotation symmetry and adopts an E-configuration about the central olefinic bonds. The two benzene rings and the central cyclo­penta­none ring are almost coplanar [dihedral angle = 4.7 (2)°]

Control of quantum coherence of photons exploiting quantum entanglement

Accurately controlling the quantum coherence of photons is pivotal for their applications in quantum sensing and quantum imaging. Here, we propose the utilization of quantum entanglement and local phase manipulation techniques to control the higher-order quantum coherence of photons. By engineering the spatially varying phases in the transverse plane, we can precisely manipulate the spatial structure of the second-order coherence function of entangled photon pairs without changing the photon intensity distribution of each photon. Our approach can readily be extended to higher-order quantum coherence control. These results could potentially stimulate new experimental research and applications of optical quantum coherence.Comment: 9 page, 7 figures, and a supplementary materia

2-Phenyl-4-(3,4,5-trimethoxy­benzyl­idene)-1,3-oxazol-5(4H)-one

The title compound, C19H17NO5, was synthesized as part of a continuing project involving the structures of oxazolone derivatives. The mol­ecule adopts a Z configuration about the central olefinic bond. The 2-phenyl ring is slightly twisted out of the plane of the oxazolone ring system by 11.2 (2)°. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen bonds

4-{[(1,3-Benzothia­zolium-2-yl)hydra­zono](phen­yl)meth­yl}-3-methyl-1-phenyl-1H-pyrazol-5-olate monohydrate

The title compound, C24H19N5OS·H2O, was synthesized by the reaction of 4-benzoyl-3-methyl-1-phenyl­pyrazol-5-one and 2-hydrazino-1,3-benzothia­zole. Proton transfer leads to the formation of a zwitterionic structure and the mol­ecule exists in the enolate form. The pyrazolone ring makes dihedral angles of 35.4 (3), 69.7 (3) and 40.1 (3)° with the 1-phenyl, indirectly bound phenyl and benzothia­zole ring systems, respectively. The mol­ecules are linked into one-dimensional chains by a combination of N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds

Food Image Classification Based on CBAM-Inception V3 Transfer Learning

To improve the accuracy of automatic recognition and classification of food images, a classification model CBAM- InceptionV3 is proposed, which embeds the Convolutional Block Attention Module. The specific method is to split the Inception V3 model with ImageNet pre-trained weight parameters into blocks, embed CBAM modules after each Inception block, and reassemble them into a new model, embedding a total of 11 CBAM modules. This new model is used for transfer learning of Food-101 food image dataset padded and scaled to 299 pixels in both length and width, with the highest accuracy of 82.01%. Compared with the original Inception V3 model, the CBAM module can effectively improve the model's feature extraction and classification capabilities. At the same time, transfer learning can significantly improve the accuracy rate and shorten the training time compared with the training from scratch. Compared with several other mainstream convolutional neural network models, the results show that this new model has higher recognition accuracy and can provide strong support for food image classification and recognition

Numerical and Experimental Research on Cold Compression Deformation Method for Reducing Quenching Residual Stress of 7A85 Aluminum Alloy Thick Block Forging

In aeronautical machining industry, the most difficult problem to deal with is the distortion of aviation integral component, one main cause of which is the existence of quenching residual stress of forgings, especially for large-sized ones. Therefore, it is important to study the methods that can reduce the quenching residual stress. In this work, the distribution of quenching residual stress of 7A85 aluminum alloy thick block forging, as well as the effect of cold compression deformation method on reducing quenching residual stress, has been investigated by simulation. The results show that, in length direction of 7A85 aluminum alloy thick block with a large size of 260 (H) × 1150 (W) × 5300 (L) mm, quenching residual stress can be significantly reduced by about 2.5% cold compression deformation along the direction of highness, with residual stress in length direction ranging from −65 MPa to 60 MPa, compared with its counterpart after quenching from −170 MPa to 140 MPa. Then a cold compression experiment was carried out, in which the forging residual stress on the surface was measured by X-ray diffraction device. The experimental results indicate that the optimal compression deformation value is 1%-2%, reducing 70% residual stress for 7A85 aluminum alloy specimens in size of 100 (L) × 60 (W) × 40 (H) mm