Search

A novel methodology for matching of illumination-invariant and heterogeneous faces is proposed here. We present a novel image representation called local extremum logarithm difference (LELD). Theoretical analysis proves that LELD is an illumination-invariant edge feature in coarse level. Since edges are invariant in different modalities, more importance is given on edges. Finally, a novel local zigzag binary pattern LZZBP is presented to capture the local variation of LELD, and we call it a zigzag pattern of local extremum logarithm difference (ZZPLELD). For refinement of ZZPLELD, a model based weight value learning is suggested. We tested the proposed methodology on different illumination variations, sketch-photo and NIR-VIS benchmark databases. Rank-1 recognition of 96.93% on CMU-PIE database and 95.81% on Extended Yale B database under varying illumination, show that ZZPLELD is an efficient method for illumination invariant face recognition. In the case of viewed sketches, the rank-1 recognition accuracy of 98.05% is achieved on CUFSF database. In the case of NIR-VIS matching, the rank-1 accuracy of 99.69% is achieved and which is superior to other state-of-the-art methods.

An image encryption algorithm based on Zigzag transformation and 3-Dimension Logistic chaotic map by making use of the permutation-diffusion encryption structure is proposed. The algorithm consists of two parts: firstly, Zigzag transformation is used to scramble pixel position of the color image through three channels; then, 3-Dimension Logistic chaotic map is utilized to diffuse pixel values through three channels. To solve the problem of large computation and space overhead of color image encryption algorithm, the iterative chaotic sequences are used several times in the diffusion process to improve encryption efficiency. The key space of the algorithm is large enough to resist brute-force attack and simulation results show that it also has high key sensitivity, high encryption speed and the strong ability to resist exhaustive attack and statistical attack.

This chapter describes the optical properties of graphene quantum dots. It discusses the size, shape and edge dependence of the energy gap, optical joint density of states, excitons, charged excitons, optical spin blockade and optical control of the magnetic moment in triangular graphene quantum dots with zigzag edges. The electronic and optical properties of colloidal graphene quantum dots, and in particular the spectrum of band-edge excitons is described.

A number of experiments have been conducted over the past decade to study the mechanical properties of a single string of gold atoms suspended between two gold tips, using a scanning tunneling microscope (STM) or an atomic force microscope (AFM). We consider four, five, six, seven, eight and nine atom monatomic chains of gold stretched between two end atoms whose positions remain fixed while those of the rest of the atoms are relaxed. Though there is not any difference in the behavior of these chains but in order to avoid overlapping in graphs we have differentiated chains on the basis of even (4, 6, 8) atom and odd (5, 7, 9) atom chains. We use the Gupta Potential which is a many body Glue Potential describing atom- atom interactions. The distance between the end atoms is the total length of the chain and the total energy of the chain is the sum of interaction energies between all pairs of atoms. The intervening atoms are allowed to adjust their positions till minimum energy is reached. The results from this procedure show that the minimum energy configurations are zig-zag chains which straighten when stretched. The Young’s modulus is in the range of a Gigapascal. On further stretching, the chain breaks. The maximum force for these short chains to break is of the order of 1.2, 1.4, 1.3 nN for even (4, 6, 8) chains and 1.7, 1.5 and 0.99 nN for odd (5, 7, 9) chains respectively. The region of length beyond the point of inflexion represents plasticity, and therefore cannot extend to the large strains. Hence this must be unphysical and we take the maximum force to be the breaking force. These results compare well with existing literature qualitatively and quantitatively. However, for long chains, containing 15 or more atoms, the zigzag configuration is not favoured. Experimental realizations of such long monatomic chains are awaited but experimental results are available for stretching up to eight atom chain.

We present a novel enhancement method that addresses the problem of corrupted edge information in depth maps. Corrupted depth information manifests itself in zigzag edges instead of straight ones. We extract the depth information from an associated color stream and use this information to enhance the original depth map. Besides the visual results, a quantitative analysis is conducted to prove the capabilities of our approach. For this task, we introduce a new assessment technique which is based on measuring clustering similarity using the Rand index.

In this chapter, an original approach to heavy vehicles rollover risk prediction is presented and validated experimentally. It is based on the calculation of the LTR (Load Transfer Ratio) which depends on the estimated vertical forces using high order sliding mode observers. Previously, a tractor model is developed. The validation tests were carried out on an instrumented truck rolling on the road at various speeds and lane-change manoeuvres. Many scenarios have been experienced: driving straight, curved trajectories, zigzag manoeuvre and brake tests to emphasize the rollover phenomenon and its prediction to set off an alarm for the driver. In this study, the vehicle dynamic parameters (masses, inertias, stiffness..) and the static forces infrastructure characteristics (road profile, radius of curvature, longitudinal and lateral slope, skid resistance) are measured or calculated before the tests.

This chapter is devoted to checkpointing in asynchronous message-passing systems. It first presents the notions of local and global checkpoints and a theorem stating a necessary and sufficient condition for a set of local checkpoints to belong to the same consistent global checkpoint.

This paper describes the development and implementation of a behavioral-based solution for a sensing-limited robotic system in area coverage problem using the LEGO Mindstorms NXT robotics kit. The main aim is to investigate how area coverage algorithms can be implemented on a robot with limited sensing and processing capabilities to cover a given area efficiently without localization or map building as well as to compare these algorithms with each other. Interestingly, there has been limited research done in this aspect, particularly in the efficiencies of current heuristic based algorithms in commercially available robots. In this project, three behaviors: Random Walk, Spiral, and Weave are proposed. A robot was constructed to mimic a sensing limited robot and it was used to carry out the proposed behaviors to determine the most efficient behavior. During experiment, it was found that aspects such as the parameter being measured and placement of obstacles in the environment affected the perception and performance by the robot. Results showed that the zigzag motion of Weave was the most efficient movement of the three, performing consistently well under varied environments and measurements.

Scanning tunneling microscopy is a very suitable instrument for the local probing and spectroscopic characterization of individual molecules, in our case narrow graphene nanoribbons. The electronic properties of a graphene nanoribbon can be controlled by its edge structure and width. Bottom-up approaches like on-surface synthesis allow the formation of extended conjugated electronic systems. Moreover, they lead to atomically defined edges which are important as structural defects have been predicted to modify the electronic structure. We have used low temperature scanning tunneling microscopy to investigate the formation, adsorption properties, and electronic structure of single graphene nanoribbons. 10,10′-Dibromo-9,9′-bianthryl molecules were used as molecular building blocks to form graphene nanoribbons after linking of the monomers and subsequent cyclodehydrogenation. In addition to intact ribbons, the influence of various defects on the electronic states is also investigated.

A remarkably regular organization of spirals converging to a focal point in control parameter space was recently predicted and then observed in a nonlinear circuit containing two diodes. Such spiral organizations are relatively hard to observe experimentally because they usually emerge very compressed. Here we show that a circuit with a tunnel diode displays not one but two large spiral cascades. We show such cascades to exist over wide parameter ranges and, therefore, we expect them to be easier to observe experimentally.

With the synthesis of a single atomic plane of graphite, namely, graphene honeycomb structure, a new perspective for carbon-based electronics is opened. The one-dimensional graphene nanoribbons (GNRs) have different band-gap values depending on their edge shape and width. In this contribution, we report our results showing that repeated heterostructures of GNRs of different widths form multiple quantum-well structures. The widths of the constituent parts as well as the bandgap, and also the magnetic ground state of the superlattices are modulated in direct space. We provide detailed analysis of these structures and show that superlattices with armchair edge shapes can be used as resonant tunneling devices and those with zigzag edge shape have unique features for spintronic applications. We also discuss another route of functionalizing 2D graphene, 1D GNR, and superlattices with 3d-transition metal (TM) atom adsorption.

This chapter describes a series of two-dimensional (2D) expanded arene networks, also known as nanographenes, with either closed-shell or open-shell electronic structure in the ground state. These systems are further categorized into three classes on a basis of different edge structures: those with zigzag edges only, those with armchair edges only, and those possessing both. Distinctive physical properties of these 2D aromatic systems are closely related to their structural characteristics and provide great potential for them as materials for different applications.

Density functional theory (DFT) calculations are performed to determine the mechanism and origin of the intensively debated (4×1)–(8×2) phase transition of the Si(111)-In nanowire array. The calculations (i) show the existence of soft phonon modes that transform the nanowire structure between the metallic In zigzag chains of the room-temperature phase and the insulating In hexagons formed at low temperature and (ii) demonstrate that the subtle balance between the energy lowering due to the hexagon formation and the larger vibrational entropy of the zigzag chains causes the phase transition.

We propose a new quantum interference device based on a graphene nanoring attached to two leads. A lateral gate voltage applied across the nanoring creates an electric field perpendicular to the current flow and shifts energy levels of the two arms of the ring. A charge carrier being injected from the source at a given energy couples therefore to different states of the arms. Those states can be in or out of phase at the drain, resulting in interference effects, which allow for a fine control of the current between the two leads by the gate voltage. We find also that electron transport depends on the type of edges (zigzag or armchair) of the nanoring and discuss the effects of edge imperfections on the performance of the quantum interference device.

This paper gives the performance analysis of Interleave Division Multiple Access (IDMA) with different coding techniques. Convolutional coding and Zigzag coding techniques are used to improve the capacity of a channel.A new multiple access scheme has been introduced which employs the chip level interleaving as the only means of user separation. Coded IDMA is compared with un coded IDMA in this paper.

In the shape-adaptive compression algorithm, an image is divided into irregular regions instead of 8×8 blocks to achieve better compression efficiency. However, in this case, it is improper to use the conventional zigzag of JPEG to scan the DCT coefficients. For example, for a region whose height is M and width is N, if N is much larger than M, then the DCT coefficient in the location (0, b) is usually larger than that in (b-1, 0). However, when using the conventional zigzag method, (b-1, 0) is scanned before (0, b). In this paper, we propose new algorithms to perform coefficient scanning for irregular regions. The proposed methods are easy to implement and can obviously improve the coding efficiency of the shape-adaptive compression algorithm.

Solar air collector is a solar energy utilization device suitable for heating; a new solar air collector with cylindrical fin in the holes arranged in heat collecting plate was designed and studied. Three different structure of the new solar air collector were simulated. Flow patterns, temperature distribution, solar energy collecting efficiency were analyzed. Based on the simulation, solar air collector with optimal structure parameter was manufactured. The simulated results indicated that heat collecting plate with staggered holes arrangement is superior to that with lined holes arrangement, and collector with segment baffle to make the air flow in zigzag flow improved heat collecting efficiency. Heat collecting efficiency of the new designed collector is about 90%.

Graphene is a one atomic thickness carbon sheet, where the low-energy electronic states of graphene are described by the massless Dirac Fermions. The orientation of edge in graphene determines energy spectrum of the π-electrons. Zigzag edges possess edge localized states with energies close to the Fermi level. However, armchair edges do not have such localized states. In this chapter, we shall introduce the nanoscale and edge shape effect on electronic properties of graphene. Starting from the basic description of electronic states of graphene nanoribbons on the basis of tight-binding model and massless Dirac equation, we briefly introduce the transport properties of disordered graphene nanoribbons and nanojunctions.

Single-walled carbon nanotubes (CNT) can be viewed as one (or more) graphene sheet(s) rolled into a seamless tube with a diameter of the order of nanometres. The way in which the graphene sheet is wrapped is represented by a pair of indices (n,m) of the vector C that is called the chiral vector, C = n a 1 + m a 2. The integers n and m denote the number of unit vectors a 1 and a 2 along two directions in the honeycomb crystal lattice of graphene, as shown in Fig. 6.1a. If m = 0, they are called “zigzag” nanotubes and if n = m, they are called “armchair” nanotubes. For any other values of n and m the nanotubes are called “chiral”, because the chains of atoms spiral around the tube axis instead of closing around the circumference. The magnitude of the chiral vector

A reduced-order general continuum method is used to examine the mechanical behavior of single-walled carbon nanotubes (CNTs) under compressive loading and unloading conditions. Quasi-static solutions are sought where the total energy of the system is minimized with respect to the spatial degree of freedom. We provide detailed buckled configurations for four different types of CNTs and show that, among the cases studied, the armchair CNT has the strongest resistance to the compressive loading. It is also shown that the buckled CNT will significantly lose its structural strength with the zigzag lattice structure. The unloading post-buckling of CNT demonstrates that even after the occurrence of buckling the CNT can still return to its original state making its use desirable in fields such as synthetic biomaterials, electromagnetic devices, or polymer composites.

An atomic finite element model based on virtual spring model for armchair and zigzag single walled carbon nanotubes is employed to reveal the relation between axial load and frequency shift. Tersoff-Brenner potential is introduced to define the interactions between the atoms as well as the mechanical properties of the springs in the model. The fundamental frequency shifts of transverse and radial vibration modes of strained single walled carbon nanotubes are obtained by applying finite element theory and techniques. It is found that the fundamental frequencies of the two modes are typically as high as hundreds of GHz, and they decrease linearly with the increase of the stretching load, whereas grow linearly with the increase of the compression load. The frequency sensitivities of nanotubes with different diameters, chiralities and lengths are also studied. With the increase of length and diameter, both the frequency sensitivities for transverse and radial vibration modes decrease. However, exception is found in nanotubes with small diameter, and it is attributed to the small-diameter effect and the affect of boundary condition.

After an extensive research on the fundamental theory, the theoretical basis for the Logix gearing will be presented in this paper. This includes the theory for gear meshing with high degree of contact. In comparison to previous studies, the theory of this paper is more restricted going beyond third order parameters into the fourth order, the teeth profile had one order of contact higher than that of the Logix gearing. So that further improved the contact strength of tooth profile. A large category of gearings with high order of contact was presented, while the Logix gear is only one of them, or the special example in realization of my theory. In the Logix gearing, the zigzag curvature center curve of media rack does not always lay about the pitch line and does not extend along the pitch line continuously and steadily. It goes forward and returns. So that, in terms of properties of the transverse engagement, the Logix gearing has not much improvement over the traditional Novikov gearing (in which the transverse engagement is temporally). In my gearing the curvature center of basic rack extend along the pitch line continuously and steadily. The transverse engagement factor is larger than that of Logix gearing.

The present paper develops a novel strategy for the exploration of an unknown environment with a multi-robot system. Communication between the robots is restricted to line-of-sight and to a maximum inter-robot distance. The algorithm we propose is related to methods used for complete coverage of an area, where all free space is physically covered. In the present paper it is required that the entire free space is covered by the sensors of the robots, enabling us to scan more space in less time, compared to complete coverage algorithms. The area to be scanned contains disjoint convex obstacles of unknown size and shape. The geometry of the robot group has a zigzag shape, which is stretched or compressed to adapt to the environment. The robot group is allowed to split and rejoin when passing obstacles. A direct application of the algorithm is mine field clearance.

The performance of TFRC algorithm is low in the unreliable and dynamic wireless environment. In particular, the packet loss used in TFRC can be caused either by the wireless error or congestion in wireless networks. Based on the analysis of loss differentiate algorithms such as Biaz and ZigZag, we propose the WLD algorithm aiming to differentiate more precisely between the wireless error and congestion loss. The simulation results show WLD algorithm improves remarkably the throughput of streaming in wireless networks, thus improves the performance of congestion control algorithm such as TFRC for media streaming in wireless networks.

The inorganic analogs of carbon fullerenes and nanotubes, like MoS2 and BN, are reviewed. It is argued that nanoparticles of 2D layered compounds are inherently unstable in the planar configuration and prefer to form closed cage structures. The progress in the synthesis of these nanomaterials, and, in particular, the large-scale synthesis of BN, WS2 and V2O5 nanotubes, are described. Some of the electronic, optical and mechanical properties of these nanostructures are reviewed. The red-shift of the energy gap with shrinking nanotube diameter is discussed as well as the suggestion that zigzag nanotubes exhibit a direct gap rather than an indirect gap, as is prevalent in many of the bulk 2D materials. Some potential applications of these nanomaterials are presented as well, most importantly the superior tribological properties of WS2 and MoS2 nested fullerene-like structures (onions).

Shape description is the precondition for shape matching and retrieval. The more robust and stable primitives to describe shapes are global topological properties, but obtaining global topological properties is still an obstacle in computer vision. Motivated by the difference sensitivity of short-range connection in biology vision, we present a novel global descriptor to describe the entire topology of simple closed 2D shape in this paper. We employ two novel strategies --- the zigzag rule, which approximates shape to an elaborate polygonal curve, and cost function which combines global configurations as well as local information of the line stimulations as our punishments. With these two key steps the descriptor is robust to translation, scaling and rotation. Experimental results show the model gain good performance on matching and retrieval for silhouettes. Even for images with occlusion the result is excellent and reasonable.

The molecular dynamics simulations originally performed by Fermi, Pasta, and Ulam for an isolated one-dimensional chain with cubic anharmonicity had led afterwards to the discovery of stable coherent structures called “solitons”. Any study of the stability of solitons on such a one-dimensional lattice with respect to transverse motions of chain atoms or molecules requires introduction of a secondary structure realized for biological macromolecules in the form of a helix. In the simplest case of intermolecular interactions with spherical symmetry, the straightforward generalization of the Fermi-Pasta-Ulam chain to higher dimensions gives rise to the helical structure: zigzag in two dimensions and α-helix in three dimensions. The planar zigzag structure is provided by the first-and second-neighbor intermolecular bonds, whereas the helical structure in three dimensions requires for its stabilization, at least, three types of interactions. The coupled nonlinear field equations that describe longitudinal and transverse displacements of molecules in the helix backbone are studied. In particular, stable non-topological two- and three-component soliton solutions in two and three dimensions, respectively, are shown to exist. These solutions describe supersonic pulses of longitudinal compression propagating together with localized transverse thickening (“bulging”) and torsional stretching (twisting). Other, more specific, types of solitons are investigated in two dimensions for the zigzag backbone.

Zigzag pocket machining (or 2D-milling) plays an important role in the manufacturing industry. The objective is to minimize the number of tool retractions in the zigzag machining path for a given pocket (i.e., a planar domain). We give an optimal linear time dynamic programming algorithm for simply connected pockets, and a linear plus O(1)O(h) time optimal algorithm for pockets with h holes. If the dual graph of the zigzag line segment partition of the given pocket is a partial k-tree of bounded degree or a k- outerplanar graph, for a fixed k, we solve the problem optimally in time O(n logn). Finally, we propose a polynomial time algorithm for finding a machining path for a general pocket with h holes using at most OPT+eh retractions, where OPT is the smallest possible number of retractions and e>0 is any constant.

For extending of hot-spot of wireless LAN (WLAN), [1] proposes internetworking scheme between WLAN and mobile ad-hoc network (MANET), which employ the same layer-2 protocol with different mode. Compared to internetworking schemes between UMTS (Universal Mobile Telecommunications Systems) and WLAN [3-4], the scheme from [1] has relatively low overhead and latencies because WLAN and MANET are physically and logically similar to each other. However, the mode switching algorithm proposed in [1] for internetworking only considers signal strength and determines handoff, and mobile nodes following a zigzag course in pollution area may frequently perform handoff at short intervals. Furthermore, [1] employs mobile IPv6 (MIPv6) at base, which brings still high delay on handoff and overhead due to signal message exchange. In this paper, we present optimized internetworking scheme between WLAN and MANET, modified from [1]. To settle ping-pong handoff, we propose adaptive mode switching algorithm. HMIPv6 is employed for IP connectivity and mobility service in WLAN, which solves some shortcomings, such as high handoff overhead and vulnerable security from MIPv6. For routing in MANET, OLSR is employed, which operates with current IP protocol compatibly with no change or modification. The proposed internetworking scheme based on adaptive mode switching algorithm shows better performance than scheme from [1].

In this paper, we propose a computation-efficient DCT-based encoding algorithm for the standard video encoders. Most video coding standards consist of DCT and associated modules such as quantization, zigzag scan, VLC (Variable Length Coders). Commercial and standard video encoders implement the modules independently. In this paper, the relationship between the function modules is investigated and the unnecessary operations are removed. The simulation results show that the proposed method reduces the computation complexity of IDCT by 40 % compared with standard implementation.

Recently QoS guaranteed real-time data support with user mobility in wireless Internet becomes more significant due to drastic increase of network users called netizens. Mobile IP(MIP) supporting user mobility evolves from versions v4 to v6 with comprehensive analysis of mobile users. However, Mobile IPv6 still has the buffering problem and problems occurred by the zigzag effect. In this paper, we propose a new MIPv6 handoff mechanism called partial dual unicasting(PDU) based on QoS supported RSVP signaling protocol. This scheme reduces the handoff failure rate up to about 24% and guarantees the time for the handoff completion. Furthermore, it resolves the ineffectiveness of path usage in dual unicasting(DU).

In this paper, we determine a cutting direction which minimizes the tool retraction length in a zigzag pocket machining. A tool retraction, in a zigzag pocket machining, is a non-productive operation in which the tool moves to any remaining regions for machining. We developed an algorithm of generating a tool retraction length in simple polygonal shapes. In the algorithm, we considered a reflex profile of cutting direction in a polygonal shape. Considering reflex profiles of cutting direction, the polygon is decomposed into several subregions, which do not need any tool retractions. Consequently, we propose a new result that the tool retraction can be minimized when a cutting direction is parallel to concave edges. Examples are shown to show the validity.

Expansion of graphs can be given equivalent definitions in combinatorial and algebraic terms. This is the most basic connection between combinatorics and algebra illuminated by expanders and the quest to construct them. The talk will survey how fertile this connection has been to both fields, focusing on recent results. In particular, I will explain the zigzag product, and how it enables better constructions and new applications.

This article reviews the electronic properties of plain and doped nanotubes. The effect of doping on transport is then discussed. Novel transport properties are obtained for N-P doped nanotubes. It will be shown that N-P junctions of semiconducting zigzag tubes have a rectifying behavior whereas those of metallic armchair tubes have a negative differential resistance. These effects become more pronounced as the tube radius is reduced. Such interesting and novel properties may be used for designing new nanoscale devices. In a second part, mechanical properties of the tubes and the effect of defects on them will be discussed. This section will be illustrated by the results of molecular dynamics simulations.

Numerical simulations of laminar flows are a useful tool for designing effective mixing devices for microsystems. A finite element model has been used in order to examine the channel geometry for a zigzag micromixer integrating a ∼Y” junction. The results illustrate the effects of flow rate and channel geometry on the hydrodynamics and mixing efficiency. Finite element simulations illustrate the mixing effect of laminar flow recirculations.

Cleaved Si(111) and Ge(111) surfaces exhibit 2 × 1 reconstructions. Initially, a buckling of the top atom-layer was thought to explain the respective atomic rearrangement in the surface. However, this simple model had to be discarded since the shifts experimentally observed with Si(2p) and Ge(3d) core levels were much smaller and the dangling-bond bands much wider than what was to be expected from calculations for buckled surfaces. Later on, the 2 × 1 reconstructions on Si and Ge(111) surfaces were proposed to consist of zigzag chains along a >110< direction which are joined to the underlying bulk by five- and seven-member rings while six-member rings are characteristic for the bulk of diamond-structure solids. The formation of such chains was proposed to proceed by a generation of stacking faults. Chains of surface atoms intuitively account for wider bands of dangling-bond surface states since the atoms are then more closely spaced. Additionally, the chains have to be tilted. This is again intuitively concluded from the surface core-level shifts experimentally observed and also resulted from evaluations of experimental I/W p curves of LEED spots by using dynamical theories of LEED. Tilted chains as stable atomic arrangements on Si(111) surfaces were also obtained from static minimizations of the total energy as well as from a molecular-dynamics approach.

This Paper proposes ZigZag, a new clustering algorithm, that works on categorical variable Cross-classification tables. Zigzag creates simultaneously two partitions of row and column categories in accordance with the equivalence relation ”to have the Same conditional mode” . These two partitions are associated one to one and onto, creating by that way row-column clusters. Thus, we have an efficient KDD tool which we tan apply to any database. Moreover, ZigZag visualizes predictive association for nominal data in the sense of Guttman, Goodman and Kruskal. Accordingly, the prediction rule of a nominal variable Y conditionally to an other X consists in choosing the conditionally most probable category of Y when knowing X and the power of this rule is evaluated by the mean proportional reduction in error denoted by λ Y/X . It would appear then that the mapping furnished by ZigZag plays for nominal data the Same role as the scattered diagram and the curves of conditional means or the straight regression line plays for quantitative data, the first increased with the values of λ Y/X and λ X/Y , the second increased with the correlation ratio or the R2.

We extend the notion of free hull to the zigzag operation in order to build the z-free hulls of a language. We present some properties of those z-free hulls and, specially, we show that a language can have several z-free hulls whereas the free hull is always unique. We also study the defect theorem which becomes false for the zigzag case. Then we are interested by a problem closed to the defect theorem and we solve it in some particular cases.