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Hybrid pencil beam model (HPBM) based on photon characteristic line algorithm has been presented to get accurate three-dimensional (3D) dose distribution for lung radiotherapy in small fields. In the model, we introduced a scattering factor to accurately describe the transport behavior of scattered photons and secondary electrons, combined with the equivalent depth correction and the weighted density correction. The pencil beam kernels of heterogeneous lung phantoms were redefined by the scattering factor and depth dose for a reference field by photon characteristic line algorithm. Subsequently, the 3D dose distribution in lung phantoms with density of 0.1, 0.26, and 0.4 g/cm3, was calculated by the Finite-size pencil beam algorithm in five regular fields and an irregular field for 6 MV photon beam. The dose distributions obtained by the HPBM are in agreement with those obtained by the MC simulations, with a relative error of less than 3% in most of the cases. However, there are apparent discrepancies at media interfaces and lung anterior portion. Moreover, at media interfaces, relative dose errors of the two methods decrease with the increase in field size and lung density. The depth range in which relative errors is greater than 3% increases with the increase in field size at lung anterior portion. In these examples, maximum relative errors are between 5 and 29%. Nevertheless, it is shown that the HPBM based on photon characteristic line algorithm has potential research values in lung dose calculation under conditions of small fields.

The multifaceted nature of sensor data has long been a hurdle for those seeking to harness its full potential in the field of 3D object detection. Although the utilisation of point clouds as input has yielded exceptional results, the challenge of effectively combining the complementary properties of multi‐sensor data looms large. This work presents a new approach to multi‐model 3D object detection, called adaptive voxel‐image feature fusion (AVIFF). Adaptive voxel‐image feature fusion is an end‐to‐end single‐shot framework that can dynamically and adaptively fuse point cloud and image features, resulting in a more comprehensive and integrated analysis of the camera sensor and the LiDar sensor data. With the aid of the adaptive feature fusion module, spatialised image features can be adroitly fused with voxel‐based point cloud features, while the Dense Fusion module ensures the preservation of the distinctive characteristics of 3D point cloud data through the use of a heterogeneous architecture. Notably, the authors' framework features a novel generalised intersection over union loss function that enhances the perceptibility of object localsation and rotation in 3D space. Comprehensive experimentation has validated the efficacy of the authors' proposed modules, firmly establishing AVIFF as a novel framework in the field of 3D object detection. [ABSTRACT FROM AUTHOR]

In order to investigate the changes of volatile flavor substances in the process of beeves spoilage, beeves with different storage time were employed. The volatile flavor substances of beeves in spoilage process were analyzed by using gas chromatography ion transfer spectroscopy (GC-IMS) and electronic nose. The results showed that a total of 55 volatile flavor substances were detected through GC-IMS, mainly including 12 ketones, 10 alcohols, 9 esters, 8 aldehydes and 4 hydrocarbons. GC-IMS and electronic nose analysis indicated that the types and contents of volatile flavor substances significantly increased during the spoilage process. The alcohols, aldehydes, esters, acids, furans, pyrroles, thiophenes, amines, pyridines and ethers continuously increased during the spoilage process. However, ketones, hydrocarbons, and sulfur compounds gradually increased and reached peak at the seventh day, and then gradually decreased. PCA and PLS-DA analysis suggested that there were significant differences in volatile flavor substances of beeves in spoilage process. Sixteen different volatile flavor substances were identified by variable importance for the projection (VIP) value, with the extension of storage, the contents of irritating and unpleasant flavor substances such as n-hexanal-D, n-hexanal-M, butyraldehyde-M, butyraldehyde-D, tetrahydropyrrole-M, isoamyl-D, isoamyl-M, n-propanol-D, 2,3-butanedione gradually increased, which could be used as potential biomarkers to distinguish beeves with different degrees of spoilage. This work provides a theoretical basis for monitoring beef spoilage process. [ABSTRACT FROM AUTHOR]

The existing researches have concluded that the number of gravity heat pipes, insertion depth and angle, filling rate, working fluid will affect the distribution of the internal temperature field of coal pile. However, there are few researches on the optimal arrangement of gravity heat pipes in coal pile. In order to solve the above problems, based on the gravity heat pipe heat transfer theoretical model, the heat source is equivalent to a sphere, and the effect of gravity heat pipe arrangement on the high temperature point of coal pile is analyzed by a combination of numerical simulation and experiment, and the optimal arrangement of gravity heat pipe is derived. The numerical simulation results based on Comsol software show that the depth of gravity heat pipe insertion has greater effect on the temperature of the high-temperature heat source point inside coal pile than the inclination angle of gravity heat pipe insertion. Under the same angle, the greater the gravity heat pipe arrangement depth is, the better. This means that the closer to the heat source, the better. Under the same depth, when the gravity heat pipe arrangement angle is 60, 90, 45 and 30°, the cooling range decreases in order. When the insertion depth of gravity heat pipe is 60 cm and the insertion angle is 60°, the highest cooling range reaches 61.2 ℃, and the coal pile has the best cooling effect. The experimental results based on the coal storage pile heat transfer test bench show that the optimal arrangement of gravity heat pipes is consistent with the simulation results, and the overall trend of the cooling rate is similar to the simulation results. With the increase of the inclination angle, the cooling rate of heat pipe decreases first and then increases, and the cooling rate reaches the maximum when the inclination angle of heat pipe insertion reaches 60°.

As the most popular mechanism, the generalized Snell's law has been applied extensively to design metasurfaces for wave manipulation. By modulating phase profile using metasurfaces, various novel wave transformations have been demonstrated. However, it has been found that the performance of these metasurfaces cannot be fully determined by the generalized Snell's law and in some cases, the wave fields appear to be contradictory to what predicted by the generalized Snell's law. In this work, a systematic numerical study is conducted to investigate the generalized Snell's law for elastic waves. The inherent assumptions of the generalized Snell's law are examined first followed by the study of the effects of various implementation issues on the performance of the metasurfaces. In particular, the fundamental mechanism for producing wave components that do not obey the generalized Snell's lay is identified and theoretically justified. Design guidelines for metasurfaces for improved performance are provided. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate an implementation method and the results of a voxel-based self-adaptive prescription dose optimization algorithm for intensity-modulated radiotherapy.

The ability to accurately identify fire patterns is the fundamental requirement for fire investigations. The corrosion layers of steel in fire scenes exhibit three distinct characteristics. First, due to steel's nonflammable nature, steel patterns can be preserved better at the fire site than patterns formed on other combustible materials; second, both the high temperature and the smoke during the fire affect the high‐temperature oxidation process; and third, the corrosion layer of steels inevitably undergoes further evolution after the fire because of the subsequent room‐temperature corrosion. This study focuses on investigating Q235 steel because of its extensive use in construction and vehicles. The pattern evolution processes of high‐temperature oxidation at elevated temperatures in air, polyethylene (PE), and polyvinyl‐chloride (PVC) combustion smoke and the corresponding subsequent corrosion at room temperature were systematically investigated from the perspective of macroscopic and microscopic morphology. The results showed that the smoke atmosphere played an important role in the formation of the corrosion layer of Q235 steel. Compared with samples oxidized in air, samples oxidized in PE combustion smoke exhibited a uniform and dense oxide layer on the surface, which inhibited the corrosion at room temperature further. The PVC combustion smoke accelerated the high‐temperature oxidation of the sample, and its influence on the subsequent room‐temperature oxidation process was closely correlated with the temperature of the high‐temperature oxidation. The results of this study provide important references for understanding the formation of the corrosion layer of Q235 steel for fire investigations. [ABSTRACT FROM AUTHOR]