Sharif Digital Repository

Multi-layer schemes have been proposed for steganography. Also some authors have combined these methods with the idea of wet paper codes and gained higher embedding efficiency. This paper proposes a generalized multi-layer method for wet paper embedding. First, the cover bits are divided into blocks and, by combining these bits in groups of 3, a pyramid is formed. Next, the secret message is embedded through a layer-by-layer procedure. The proposed method has higher embedding efficiency in some cases and provides more flexibility for choosing the embedding payload, especially in lower payload conditions  

With rapid proliferation of affordable video capturing devices and state-of-the-art video editing software tools, it is now easier than ever to manipulate video contents. In this paper a passive method for copy/move video forgery detection in MPEG videos is proposed. The method first divides each video frame into suspicious and apparently innocent parts. Subsequently, an optical flow coefficient is computed from each part. Forgeries are located when an unusual trend in the optical flow coefficient of the suspicious object is detected. Experiments on a set of forged and original sequences validate the justifications made by the proposed method  

Adding memory to artificial intelligence systems in an effective way has been addressed by researchers for many years. Recurrent neural networks and long short-term memories (LSTMs), among other neural network systems, have some inherent memory capabilities. Recently, in memory augmented neural networks, such as neural Turing machine (NTM) and its variants, a separate memory module is implemented, which can be accessed via read and write heads. Despite its capabilities in simple algorithmic tasks, such as copying and repeat copying, neural Turing machines fail when doing complex tasks with long-term dependencies due to their limited memory capacity. In this paper, we propose a new memory... 

The wake and internal waves of a moving three dimensional (3D) airfoil body in a stratified fluid has been investigated in a large stratified tank with a finite depth using movies of shadowgraphs of the flow fields. Typical Reynolds and Froude numbers of the flow varied between 103 and 104, and 0.3 and 2 respectively. The flows are generated often by towing the body in a uniformly stratified flow, while limited cases are carried out with body stationary and the channel was in recirculating mode. For some experiments the density profile had a stepped like shape. The wake flow is often consisted of internal waves including random and coherent ones. Distortion of density fields was also... 

River water quality monitoring using traditional water sampling and laboratory analyses is expensive and time-consuming. The application of artificial neural network (ANN) models to simulate water quality parameters is cost-effective, quick, and reliable. This study provides two methods of mathematical and ANN modeling to simulate and forecast five important river water quality indicators (DO, TDS, SAR, BOD5, HCO3) correlated with variables such as EC, temperature, and pH which can be measured easily and almost with no cost. The mathematical method is based on polynomial fitting with least square method and the neural network model was developed using a feed-forward algorithm. The 35 years’... 

Current paper is focused on transient modeling of blood flow through a tapered stenosed arteries surrounded a by solenoid under the presence of heat transfer. The oxygenated and deoxygenated blood are considered here by the Newtonian and Non-Newtonian fluid (power law and Carreau-Yasuda) models. The governing equations of bio magnetic fluid flow for an incompressible, laminar, homogeneous, non-Newtonian are solved by finite volume method with SIMPLE algorithm for structured grid. Both magnetization and electric current source terms are well thought-out in momentum and energy equations. The effects of fluid viscosity model, Hartmann number, and magnetic number on wall shear stress, shearing... 

The basic goal of this article is to present an abstract system-theoretic approach to morphological filtering and the theory of translation invariant systems which is mainly based on residuated semigroups. Some new results as well as a number of basic questions are also introduced  

In a previous paper we introduced a generalized model for translation invariant (TI) operators. In this model we considered the space, φ of all maps from an abelian group G to ω U {-∞}, called LG-fuzzy sets, where ω is a complete lattice-ordered group; and we defined TI operators on this space. Also, in that paper, we proved strong reconstruction theorem to show the consistency of this model. This theorem states that for an order-preserving TI operator Y one can explicitly compute Y(A), for any A, from a specific subset of φ called the base of Y. In this paper duality is considered in the same general framework, and in this regard, continuous TI operators are studied. This kind of operators... 

We consider translation invariant (TI) operators on Φ, the set of maps from an abelian group G to Ω ∪ {−∞} , called LG-fuzzy sets, where 0 is a complete lattice ordered group. By defining Minkowski and morphological operations on Φ and considering order preserving operators, we prove a reconstruction theorem. This theorem, which is called the Strong Reconstruction Theorem (SRT), is similar to the Convolution Theorem in the theory of linear and shift invariant systems and states that for an order preserving TI operator Y one can explicitly compute Y ( A ), for any A , from a specific subset of Φ called the base of Y . The introduced framework is a general model for the theory of translation... 

The main goal of this paper is to verify classical properties of morphological operators within the general model of translation invariant (TI) systems. In this model, TI operators are defined on the space of LG-fuzzy sets Φ i.e. Φ = {A: G → Ω ∪ {− ∞}} in which G is an abelian group and Ω is a complete lattice ordered group. A TI operator Y is an operator on Φ which is invariant under translation on G and Ω as groups. We consider the generalization of Minkowski addition (D on Φ and we emphasize that (Φ,⊛) is an involutive residuated topological monoid. We verify all properties of traditional (set-theoretic) morphological operators as well as classical representations (Matheron, 1967) for... 

Let G be a simple undirected uniquely vertex k-colorable graph, or a k-UCG for short. M. Truszczyński [Some results on uniquely colorable graphs, in Finite and Infinite Sets, North-Holland, Amsterdam, 1984, pp. 733--748] introduced $e^{^{*}}(G)=|V(G)|(k-1)-{k \choose 2}$ as the minimum number of edges for a k-UCG and S. J. Xu [J. Combin. Theory Ser. B, 50 (1990), pp. 319--320] conjectured that any minimal k-UCG contains a Kk as a subgraph. In this paper, first we introduce a technique called forcing. Then by applying this technique in conjunction with a feedback structure we construct a k-UCG with clique number k-t, for each $t \geq 1$ and each k, when k is large enough. This also... 

In this paper, we derive some necessary spectral conditions for the existence of graph homomorphisms in which we also consider some parameters related to the corresponding eigenspaces such as nodal domains. In this approach, we consider the combinatorial Laplacian and co-Laplacian as well as the adjacency matrix. Also, we present some applications in graph decompositions where we prove a general version of Fisher’s inequality for G-designs  

Let d(σ)d(σ) stand for the defining number of the colouring σσ. In this paper we consider View the MathML sourcedmin=minγd(γ) and View the MathML sourcedmax=maxγd(γ) for the onto χχ-colourings γγ of the circular complete graph Kn,dKn,d. In this regard we obtain a lower bound for dmin(Kn,d)dmin(Kn,d) and we also prove that this parameter is asymptotically equal to χ-1χ-1. Also, we show that when χ⩾4χ⩾4 and s≠0s≠0 then dmax(Kχd-s,d)=χ+2s-3dmax(Kχd-s,d)=χ+2s-3, and, moreover, we prove an inequality relating this parameter to the circular chromatic number for any graph G