bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel image quality evaluation method based on two-dimensional information entropy
Authors: yi Liu , Zili Huang , Fangyuan Yu , Guochuan Lin , jing Zeng , mengmeng Ma , li Zhan , xiang Zhang 
Published: June 2023

Abstract
In image transmission, with the consideration of system parameters, such as bandwidth, transmission delay and power consumption, the image compression coding is often used to reduce the amount of transmitted data. The formation mechanism of block effect in H.264 coding is analyzed. Taking H.264 coding as an example, the spatial domain image enhancement processing is adopted in the paper to obtain the two-dimensional information entropy covering the gray correlation and image edge feature information in adjacent spatial domain. By referring to the two-dimensional information entropy evaluation value of original and coded image, the image quality evaluation result is consistent with PSNR method used in common situations. Compared with the traditional PSNR evaluation method, the two-dimensional information entropy evaluation method only refers to the two-dimensional information entropy evaluation value of the original image, and the amount of data required is very low. Therefor, it is more suitable for the engineering implementation of real-time image quality evaluation in image transmission system. At the same time, with the edge feature information of the image used in the two-dimensional information entropy, the entropy method is closer to the actual feeling of human eyes than PSNR method.
Lightweight-YOLOv5s for the camouflaged personnel detection in the woodland
Authors: Xu Bin , Wang Congqing , Liu Yang , Zhou Yongjun 
Published: June 2023

Abstract
Unmanned aerial vehicles(UAVs) technology and target detection technology are increasingly integrated. However, the target detection networks are cumbersome and complex, and it is hard to directly deploy these networks on the UAVs. To address this problem, a Lightweight-YOLOv5s which can be applied to the UAVs is proposed to detect the camouflaged personnel in the woodland. Depthwise separable convolutions are added to the YOLOv5s for reducing the parameters and computational effort. Then a new channel pruning method based on Batch Normalization(BN) layer scaling factor with adaptive sparsity training is proposed for network compression, which can balance the compression ratio and accuracy of the detection. The pruned network is then fine-tuned to detect the camouflaged personnel. In addition, a special dataset is built for the camouflaged personnel detection in the woodland. The quantitative results on this dataset prove that the proposed Lightweight-YOLOv5s greatly improve the YOLOv5s. Parameters from 7.06M to 1.86M, floating point operations from 16.4G to 9.9G and inference time from 8.16ms to 7.06ms. Besides, mAP of the Lightweight-YOLOv5s is 0.83, which shows the excellent detection performance of the proposed method.
An unsupervised aerial tracking method of camouflaged targets in complex environments
Authors: Liu Yang , Wang Cong-qing , Xu Bin , Zhou Yongjun 
Published: June 2023

Abstract
With the widespread use of UAVs and the development of various technologies related to computer vision, much attention has been devoted to UAV-based target tracking. For the task of tracking camouflaged people in complex environments, there is a shortage of annotated datasets and poor backbone feature extraction network capabilities, which will cause tracking drift and tracking lag. To achieve unsupervised UAV target tracking under unsupervised conditions, a new target tracking model has been designed. First, we roughly detect moving targets using a camouflaged segmentation network, and then apply dynamic programming to generate smooth candidate boxes. Secondly, a deeper convolutional neural network is designed for feature extraction to replace the original backbone network, and the residual structure is modified to ensure tracking effectiveness. Extensive comparative experiments have shown that the proposed unsupervised method performs the task of UAV target tracking well.
Low-light image enhancement based on Retinex theory for beam-splitting prism system
Authors: Liu Haozhou , Zhang Wenwen , He Weiji 
Published: June 2023

Abstract
The existing color image enhancement methods are utilized for the most part to directly improve the color image that is obtained through the use of a Bayer array camera, whereas the color image that is obtained through the use of a prism camera is the result of the fusion of three primary color images that have been collected independently. As a result, a method for enhancing color photographs based on three images of primary colors that have a low level of light has been proposed. In this paper, we first transfer RGB to HSV space for image enhancement. In the V channel, we use guided filtering combined with improved SSR method to better preserve edge information. Then the S channel is adjusted adaptively to make the image look more natural. Finally, the image is transferred from HSV space back to RGB space. Compared with other traditional methods, our method achieves better results in PSNR, SSIM and NIQE, and has less computational complexity.
Unsupervised Terahertz Image Restoration Based on CycleGan
Authors: Su Zhipeng , Zhang Yixiong , Qi Feng , Shi Jianghong 
Published: June 2023

Abstract
Terahertz (THz) is considered as one of the key technologies for sixth generation communications, military, medical imaging and industrial inspection. THz images are susceptible to degradation due to system noise and point spread functions during transmission. The existing deep learning methods use ground truth and input images for supervised training that can recover THz images very well. But it’s difficult to obtain labeled THz data in practical application. In this paper, we propose an attentional adversarial cycle generation network for THz image restoration (CycleTHz) based on CycleGan to address this problem. The CycleTHz generates clean images firstly by an attention-guided generation network and then discriminates the quality of the generators by an attention discriminator. In addition, RGB color loss is used for image channels for constraint. To the best of our knowledge, this is the first THz dataset to be trained using an unsupervised approach. Extensive experiments show that the proposed method improves the PSNR and SSIM by 43.4% and 101.7% compared with CycleGan, which is a benchmark method for the unsupervised development in THz image restoration. The code is available at https://github.com/hellogry/UnsupervisedCycleTHz
The Simulation of the Terahertz Modulator by CMOS Process
Authors: Zhang Chenyu , Hu Nairui , Liu Zhaoyang 
Published: June 2023

Abstract
The paper introduced the simulation of the terahertz modulator in complementary metal-oxide-semiconductor (CMOS) process. The modulator is composed of a metal split-ring resonator (SRR), CMOS, semiconductor dielectric layer and silicon substrate. The modulator can make different electromagnetic response to the transmitted terahertz wave between the connection state and the disconnection state of the gap in the SRR, which could be achieved by connecting CMOS in the gap. At 0.31THz, the simulation results show that the amplitude modulation depth of the modulator reached 28.8%. When the simulation keeped the modulator system in resonating state, the transmission coefficient was about 0.0018, while the conductive had reached 0.2895. If the design can pass the experimental verification in the future, it can make some references for further exploration of the high-speed and high modulation depth of the terahertz amplitude modulator.
Influence of Rock Layer Thickness on the Penetration Resistance of a Composite Target
Authors: Xiaojing Zhang , Wenjin Yao , Wenbin Li , Xintao Zhu , Hongxin Huang 
Published: June 2023

Abstract
To describe the influence of rock thickness on the penetration resistance of rock-concrete composite targets, a three-dimensional model was simulated using the nonlinear dynamic simulation software LS-DYNA. The penetration of four composite targets with rock-concrete thicknesses of 10-20, 20-20 cm, 30-20 and 40-20 cm by a projectile at a target angle of 75 degrees is investigated in this study. A damage cloud diagram of the target plate is obtained, and the curves of penetration speed and overload in the X and Y directions of the projectile with time are analysed. During penetration, the rock and concrete layers tend to restrain each other from destroying the target’s back and surface, and the projectile directly enters the tunnel area of the concrete layer from the tunnel area of the rock layer. When the ratio of rock thickness to shot length is less than 1.5, the attitude of the projectile after penetrating the composite target is relatively stable.
Research on Ballistic limit model for a typical 93W ball-Q235 steel plate projectile target system
Authors: Xuncheng Guo , Dongjiang Zhang , Mingxue Zhou , Shushan Wang , Lei Zhang 
Published: June 2023

Abstract
A representative and most commonly used ballistic target system consisting of a 93W ball and Q235 steel plate is investigated for its ballistic limit fast calculation engineering model. The basic data on the material of the projectile target system was obtained through quasi-static compression tests on the mechanical properties of 93W ball and Q235 steel plate materials. Using a Φ12.7mm ballistic gun and the ten shot v50 ballistic limit method, tests were carried out with 93W balls positively penetrating Q235 steel target plates and v
50 was obtained for 3g of 93W balls penetrating 6mm and 8mm thick Q235 steel plates respectively. Based on the Autodyn platform, a numerical simulation model of a 93W ball intruding through a Q235 steel target plate was established and the accuracy of the simulation model was verified using test data. On this basis, the range was extended to obtain v
50 for a total of 34 working conditions with 93W ball masses between 1 and 6g and Q235 steel target plate thicknesses between 2 and 12mm, and the v
50 engineering calculation model for 93W ball intrusion into Q235 steel plate was obtained by multiple linear regression. Comparative analysis with other representative v
50 engineering models shows that the resulting v
50 calculation model has a greater range of applicable speeds, higher accuracy and greater practicality. The results of the research can provide basic methods and tools for the design of warhead power, target protection, and the assessment of the destructive effectiveness of weapons and ammunition.
Thickness Equivalent Method of 921A and Q235 Steel Plate Based on the Similarity of Projectile Penetration Residual Velocity
Authors: Han L , Jiang H Y 
Published: June 2023

Abstract
The penetration judgment of the projectile to the target is vital to evaluate its damage ability. Based on the similarity of projectile penetration residual velocity, the thickness equivalent model of plates with different materials is proposed in this paper. Simulation parameters are validated by physical experiments. Then a series of numerical simulations are carried out on 30CrMnSiNi2A projectiles penetrating 921A and Q235 steel target plates. Results show that with the increase of the plate thickness, the projectile residual velocity decays linearly, while the slope depends on the incident velocities. Simultaneously, the residual velocity conforms to a logarithmic growth as the mass of the projectile increases. Finally, the thickness equivalent relationship between 921A and Q235 steel plate is established by using the ratio of the material strength, the incident angle and the projectile shape coefficient. The proposed model can provide a reference to the general projectile penetration analysis.
Numerical Simulation Research on Characteristics of Underwater Explosive Bubble Jet in Offshore Water
Authors: Chen Si , Qin Jian , Meng Xiangyao , Wen Yanbo , Huang Ruiyuan 
Published: June 2023

AbstractUnderwater explosions have always been a hot topic in the field of ship protection. When explosives explode in offshore waters, the influence of seabed and structural boundaries on shock wave propagation and bubble pulsation will become more complicated. In this paper, a numerical simulation study of the underwater explosion between a deformable seabed and a rigid boundary is carried out. Firstly, the ABAQUS software was used to establish a numerical model by using the CEL method. The seabed was regarded as a heavier fluid, and the density ratio of the seabed and water was used to describe the characteristics of the seabed. The validity of the model was verified by comparison with experiments. Then, a series of numerical simulations were carried out by adjust the position of the explosive, the thickness of water medium layer, and the density of the seabed. The results show that: when the position of the explosive is close to the seabed and the rigid boundary, the bubble pulsation period is longer. The water jet and the pulsating pressure of the bubbles have a strong impact on the structure when the explosive is located near to 1 times the theoretical maximum radius of the bubble. As the depth of the water decreases, it can be observed that the bubbles transform from “ellipsoid” to “nipple-like”, and finally tear into upper and lower halves. When the thickness of water medium layer is 1 times the theoretical maximum radius of the bubble, the incident pressure waveforms of the bubble pulsation and the water jet near the structure are chaotic, which is caused by the “tear” phenomenon of the bubble. As the density of the seabed increases, the depth of the intrusion of the bubbles into the seabed becomes smaller and the shape of the bubbles becomes flatter. The research results of this paper can provide reference for the protection design of ships.
Numerical Simulation of Anti-penetration Performance of Ceramic/Aramid Fiber/PE-UHMW Composite Armor
Authors: Fuqiang Li , Jingru Huang , Runhua Liu , Liang Zhao , Zheng Wang 
Published: June 2023

Abstract
In order to study the anti-penetration performance of ceramic/aramid fiber/PE-UHMW composite armor, based on the FEM-SPH coupling algorithm, SPH model is established for brittle ceramic materials to simulate the formation of ceramic cone, crack propagation and fragmentation splash process. The failure mode on aramid fiber and PE-UHMW is analyzed. The influence of different projectile velocities and impact points on the anti-penetration performance of the composite armor are analyzed. The results show that the ceramic panel in the composite armor absorbs part of the kinetic energy of the projectile through passivation, fragmentation of the projectile and panel fragmentation. The failure modes of aramid laminates are mainly delamination shear failure, bending deformation and fiber tensile fracture. The failure modes of PE-UHMW laminates are mainly compression shear failure of the projectile facing surface and small-scale delamination tensile failure of the back layer fiber. When the projectile velocity is less than the ballistic limit, the energy absorption of composite armor and the maximum deformation of back plate increase with the increase of projectile velocity. When the projectile velocity is greater than the ballistic limit, the energy absorption rate of composite armor begins to decrease. When the impact point of the projectile is located at the edge of the ceramic block, the ceramic can’t effectively consume the kinetic energy of the projectile, and the composite armor presents bad performance.
Prediction of Spatial Peak Overpressure Profile of Air Blast Shocks Using Multiple Linear Regression and Artificial Neural Network
Authors: Xi H. Z. , Kong D. R. , Peng Y. Q. , Zhang S. M. , Shi Q , Le G. G. 
Published: June 2023

Abstract
The shock peak overpressure yielded by energetic materials in the near-earth explosion causes damage to people and property. In the literature, several works have reported the effectiveness in obtaining the peak overpressure in the near field by numerical simulation, real tests, and empirical calculations. However, several issues are associated with the above methods, such as the time-consuming of a complex simulation, the difficulties in placing sensors in an obstacle block site, and the limited scope of applications for empirical equations. At present, there is no single model that can rapidly predict the spatial distribution of shock peak overpressure with ground reflection. In this regard, this paper aims to solve the problem of shock propagation in a large-scale space and obtain a model that can predict a wide range of spatial distribution of peak overpressure in the near-earth air blast simply and quickly. This work uses AUTODYN-2D to obtain the peak overpressure of the cylindrical charge explosion in the air near earth. The peak overpressure from the numerical models agrees with the empirical equations and the real blast results. On this basis, the multiple linear regression (MLR) and the optimal error back-propagation artificial neural network (ANN) models are tried and constructed with three geometric parameters as the input under a typical environment. The input parameters are the straight line scaled distance (SLSD), the vertical scaled distance (VSD), and the scaled height of burst (SHOB), respectively. The prediction results of the MLR and ANN models are verified and compared on the test set. Results show that the ANN model with the geometric parameters as the input is better than the MLR model in predicting the air blast peak overpressure. The former takes no more than 0.2s to compute 1441 sets of inputs, which provides a quick reference for predicting spatial peak overpressure in a large-scale shock wave of the air blast.
Numerical simulation and optimization design of the landmine blast protection package
Authors: Li Nan , Li Jishan , Wang Wanpeng 
Published: June 2023

Abstract
The finite element model is established based on the bench test of the landmine blast protection package. The effect of the air gap between the landmine blast protection package and the base plate as well as the stiffness of the package on the deformation of the base plate are investigated. Aluminum sandwich landmine blast protection packages are designed and the effects on the deformation suppression of the base plate are studied using the finite element model. The results show that the air gap is not conducive to the deformation suppression of the base plate. Increasing the stiffness of the package is of benefit to the deformation suppression of the base plate, however, it is necessary to consider the influence of the corresponding increase in thickness of the package on the possible increase in the base plate deformation. The scheme, composed of one piece of 2024-T3 aluminum plate and two pieces of 7mm armored steel, is the best solution among the six aluminum sandwich schemes.
Study of linear shaped charge (LSC) jet penetrating layered targets
Authors: Xu Bin , Liu-Chun mei 
Published: June 2023

Abstract
This paper presents the results of an experimental and numerical study conducted to investigate the mechanism of penetration of linear shaped charges (LSCs) into double layered targets. A type of LSC causing less collateral damage in terms of jet residues was studied. The LSC consisted of a linear liner and case with the depth to diameter aspect ratio of 2.0. Anti-theft doors and spaced steel plates were used to represent double layered targets. The anti-theft door and the equivalent targets were penetrated with little jet residues behind the exit crater. The experiments were simulated using the commercially available software AutoDYN as a 2-D planer symmetry FEM model of the LSC penetrating a double layered target. An Eulerian mesh was used to model the LSCs whilst the double layered target was modelled using a Lagrangian mesh. A fully coupled algorithm was used for two different meshes. The data from the experiments (the shape of the breach and jet residues) were used to validate the numerical model. The validated numerical model was used to gain insights into the penetrating mechanisms of the LSC. The numerical results indicated that the penetration mechanisms of the two layers target were different. The first layer was penetrated by a continuous jet typical of a high-speed jet whereas the second layer was perforated by both a jet tip and slug characterized by a low-impact velocity projectile (slug).
Numerical simulation of penetration behavior of RHA target with biconical liner
Authors: Liu C Z , Zhou S , He S , Xiang J Y 
Published: June 2023

Abstract
The AUTODYN-2D simulation software was used to study the jet formation of single-cone and biconical shaped charge liner and the damage influence on the RHA target. The numerical simulation results show that compared with the typical single-cone shaped charge structure, the jet head formed by the biconical liner is faster and has better penetration performance on the RHA target. On this basis, the influence of standoff, liner cone angle and line thickness on the penetration characteristics of RHA target under biconical shaped charge was studied. The simulation results show that when the standoff increases from 2.0CD to 3.0CD, the penetration depth increases gradually. When the upper cone angle is 30° and the lower cone angle increases from 40° to 60°, the penetration depth of the formed jet to the target decreases gradually. When the liner thickness increases from 5mm to 6mm, the penetration depth is obviously improved.
Response behaviour and microstructural evolution of Ti6321 titanium alloy under air explosion
Authors: Yan Zhiwei , Wang Lin , Ning Zixuan , Li Yanxing 
Published: June 2023

Abstract
The titanium alloy has been used for marine structrural components because of the excellent properties. The response of material under explosion when in the service process should be carried out. In this research, the explosion test of the Ti6321 titanium of three different structure is executed to study the microstructure evolution. The optical microscope is used for observing the microstructure and adiabatic shear bands (ASB). The electron backscatter diffraction method is used to study the microstructure and recrystallization of the biamodal structural target under different charges. The result shows that the deformation of the target become larger with the increase of the charge. The ASBs have been observed in the target, demonstrating that it is an important reason for the damage. The twinning mechanism comes into play a role in the deformation of the material while dislocations become difficult to satisfy. The grain size of the bimodal material decrease with the increase of the charge. The deformed grains of the target start to recover and recrystallize at high temperature due to shock waves of explosion.