arXiv subjects

Jianhua Li

Publications and source records attributed to Jianhua Li.

82 records · Page 5Linked to original sources

arXiv2017

Problem On The Acoustic Cloak By $0$ to $R_1$ Transformation

The $0$ to $R_1$ radial spherical coordinate transformation method can be making electromagnetic (EM) invisible cloak. However the cloak by transformation optic has infinite speed and exceeding light speed etc fundamental difficulties. In this paper, we discover problem on acoustic cloak by transformation and prove that in the $0$ to $R_1$ radial spherical coordinate transformation, the pressure wave field $P(r_p)=P(r)$ is invariant, in the physical inner spherical surface boundary $r=R_1$, $P(R_1)$ is not zero. the acoustic field propagation penetrate into the inner sphere $r < R_1$.Therefore, the inner sphere $r < R_1$ can not be cloaked. The GL simulation figures of the pressure acoustic wave propagation penetrate into the inner sphere $r \le R_1$ are presented in figure 1 to figure 12.The pressure wave is setting to zero that cause the scattering wave to disturb incident pressure acoustic wave outside of the outer sphere $r \ge R_2$ that make the whole sphere $r \ge R_2$ will be deltected. GL method simulation is presented in figure 13. we discovered and proved that $0$ to $R_1$ sphere radial transformation can not be used to induce acoustic no scattering cloak.

physics.class-ph↗

arXiv2017

The $0$ to $R_1$ cylinder radial coordinate transformation can not be used to make cylinder layer electromagnetic cloak

In this paper, we discover and proved that the $0$ to $R_1$ cylinder radial coordinate transformation can not be used to make cylinder layer electromagnetic EM cloak. Because in the $0$ to $R_1$ cylinder radial coordinate transformation, the value area of the electric wave field $E_z (ρ,ϕ,z)$ and magnetic wave field $H_z (ρ,ϕ,z)$ are invariant. After $0$ to $R_1$ cylinder radial transformation,$ρ_q = R_1 + Q(ρ)$, $E_z (ρ_q,ϕ,z) = E_z (ρ,ϕ,z)$,$H_z (ρ_q,ϕ,z) = H_z (ρ,ϕ,z)$ . in the physical inner cylinder boundary, $E_z (R_1,ϕ,z) \ne 0$,$H_z (R_1,ϕ,z) \ne 0$, The cylinder EM wave field will propagation penetrate into the inner cylinder $ρ< R_1,\left| z \right| < \infty $ .Therefore, the inner cylinder $ρ< R_1,\left| z \right| < \infty $ . can not be cloaked. In many published papers on EM cylinder cloak, the $0$ to $R_1$ cylinder radial transformation is wrongfully used for their EM cylinder layer cloak.

physics.class-ph↗

arXiv2017

Computer vision-based food calorie estimation: dataset, method, and experiment

Computer vision has been introduced to estimate calories from food images. But current food image data sets don't contain volume and mass records of foods, which leads to an incomplete calorie estimation. In this paper, we present a novel food image data set with volume and mass records of foods, and a deep learning method for food detection, to make a complete calorie estimation. Our data set includes 2978 images, and every image contains corresponding each food's annotation, volume and mass records, as well as a certain calibration reference. To estimate calorie of food in the proposed data set, a deep learning method using Faster R-CNN first is put forward to detect the food. And the experiment results show our method is effective to estimate calories and our data set contains adequate information for calorie estimation. Our data set is the first released food image data set which can be used to evaluate computer vision-based calorie estimation methods.

cs.CV↗

arXiv2011

An Anti-attack Model Based on Complex Network Theory in P2P networks

Complex network theory is a useful way to study many real systems. In this paper, an anti-attack model based on complex network theory is introduced. The mechanism of this model is based on dynamic compensation process and reverse percolation process in P2P networks. The main purpose of the paper is: (i) a dynamic compensation process can turn an attacked P2P network into a power-law (PL) network with exponential cutoff; (ii) a local healing process can restore the maximum degree of peers in an attacked P2P network to a normal level; (iii) a restoring process based on reverse percolation theory connects the fragmentary peers of an attacked P2P network together into a giant connected component. In this way, the model based on complex network theory can be effectively utilized for anti-attack and protection purposes in P2P networks.

cs.NI↗

arXiv2010

A GL Double Layer EM Cloaks In Broad Frequency Band And Reciprocal Law

In this paper, we propose a novel GLWF double layer EM cloak in the broad frequency band. The GLWF double layer cloak consists of two sphere annular layers, two type cloak materials are proposed and installed in its each layer, respectively. The outer layer of the GL cloak has the invisible function in broad frequency band, while its inner layer has the fully absorption and rapid delay function. The GLWF double layer cloak overcomes the following difficulties of the single layer PS cloak. (1) There exists no EM wavefield can be excited inside the concealment of the PS cloak, the concealment of the PS cloak is blind. Our GL double layer cloak recovered that the EM wave field can be excited inside the concealment of the GL double layer cloak. (2) There is exceeding light speed physical violation in PS cloak, its invisibility only in very narrow frequency band. Our GLWF double layer cloak corrects the violation. (3) The reciprocal law is satisfied in our GL double cloak media. However, the PS cloak damaged the reciprocal law.. The simulations and comparisons of the EM wave field propagation through the GLWF double cloak, GL double cloak and GL double layer with PS outer layer are presented to show the advantages of the GLWF double layer EM cloak The GL double layer cloaks are proposed by our GL EM modeling and inversion. The 3D GL EM modeling simulations for the double layer cloak are presented. The copyright and patent of the GLWF double layer cloak materials and GL EM modeling and inversion in this paper are reserved by authors in GL Geophysical Laboratory.

physics.optics↗

arXiv2009

A Double Layer Electromagnetic Cloak And GL EM Modeling

In this paper, we propose a novel electromagnetic (EM) cloaking structure that consists of two annular layers between three spherical shells and model its performance numerically and theoretically by using a Global and Local EM field (GL) method. The two annular layers contain distinct cloaking materials: the outer layer provides invisibility; the inner layer is fully absorbing. The cloaking materials are weakly degenerative. The wavefield from an EM source located outside the cloak propagates as in free space outside the outer shell, never be disturbed by the cloak and does not penetrate into the inner absorbing layer and concealment. The field of a source located inside inner layer or the cloaked concealment is completely absorbed by the inner layer and never reaches the outside of the middle shell, Moreover, the EM wavefield excited in concealment is not disrupted by the cloak. There exists no Maxwell EM wavefield can be excited in a single layer cloaked concealment which is filled by normal material. Moreover, we find a negative dielectric and positive susceptibility metamaterial to fill into the concealment, such that the interior EM wave propagates from the concealment to free space through the single layer cloak. Therefore, the double layer cloak is important and necessary for complete invisibility. Numerical simulations and theoretical analysis verifying these properties are performed using the GL EM modeling method that we described in this paper.

physics.optics↗

arXiv2009

An Electromagnetic GL Double Layered Cloak

In this paper, we propose a new electromagnetic (EM) GL double layered cloak. The GL double layered cloak is consist of two sphere annular layers, $R_1 \le r \le R_2$ and $R_2 \le r \le R_3$. Two type cloak materials are proposed and installed in the each layer, respectively. The outer layer cloak of the GL double layered cloak has the invisible function, the inner layer cloak has fully absorption function. The GL double layered metamaterials are weak degenerative and weak dispersive. When the source is located outside of the GL double layered cloak, the excited EM wave field propagation outside of the double layered cloak is as same as in free space and never be disturbed by the cloak; also, the exterior EM wave can not penetrate into the inner layer and concealment. When local sources are located inside of the GL double cloaked concealment with the normal EM materials, the excited EM wave is propagating under Maxwell equation governing, it is complete absorbed by the inner layer cloak of GL double cloak and never propagate to outside of the inner layer of the GL cloak, moreover, the EM wavefield in concealment never be disturbed by the cloak. The GL doubled layered cloak is a robust cloak and has complete and sufficient invisibility functions. Its concealment is the normal electromagnetic environment. Our EM GL double layered cloak is different from conventional common cloak. The 3D GL EM modeling simulations for the double layered cloak are presented. The GL method is an effective physical simulation method and is fully different from the conventional methods. It has double abilities of the theoretical analysis and numerical simulations to study the cloak metamaterials and wide materials and field scattering problem in physical sciences.

physics.optics↗

arXiv2009

No Maxwell Electromagnetic Wave Field Excited In Cloaked Concealment

The GL electromagnetic (EM) modeling is used to simulate the 3D EM full wave field propagation through cloaks. The 3D GL simulation of the EM wave field excited by a point source outside of the cloaks has been done. The simulation of the EM wave field from the point source excitation inside of the cloak device is presented in this paper. By using the GL modeling simulation, we found a phenomenon that there is no Maxwell EM wave field which is excited by nonzero local sources inside of the single layer cloaked concealment. The theoretical proof of the phenomenon by GL method is proposed in this paper. The GL method is fully different from the conventional methods. The GL method has double abilities of the theoretical analysis and numerical simulations to research the physical process and cloak metamaterial properties that is exhibited in this paper.

physics.optics↗

arXiv2006

Vectorial Resilient $PC(l)$ of Order $k$ Boolean Functions from AG-Codes

Propagation criterion of degree $l$ and order $k$ ($PC(l)$ of order $k$) and resiliency of vectorial Boolean functions are important for cryptographic purpose (see [1, 2, 3,6, 7,8,10,11,16]. Kurosawa, Stoh [8] and Carlet [1] gave a construction of Boolean functions satisfying $PC(l)$ of order $k$ from binary linear or nonlinear codes in. In this paper, algebraic-geometric codes over $GF(2^m)$ are used to modify Carlet and Kurosawa-Satoh's construction for giving vectorial resilient Boolean functions satisfying $PC(l)$ of order $k$. The new construction is compared with previously known results.

cs.CR↗

arXiv2006

Lower Bounds on the Algebraic Immunity of Boolean Functions

From the motivation of algebraic attacks to stream and block ciphers([1,2,7,13,14,15]), the concept of {\em algebraic immunity} (AI) was introduced in [21] and studied in [3,5,10,11,17,18,19,20,21]. High algebraic immunity is a necessary condition for resisting algebraic attacks. In this paper, we give some lower bounds on algebraic immunity of Boolean functions. The results are applied to give lower bounds on AI of symmetric Boolean functions and rotation symmetric Boolean functions. Some balanced rotation symmetric Boolean functions with their AI near the maximum possible value $\lceil \frac{n}{2}\rceil$ are constructed.

cs.CR↗