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For their good randomness and long iteration periods, chaotic maps have been widely used in cryptography. Recently, we have revealed the correlation between Lyapunov exponent and sequence randomness of multidimensional chaotic maps based on modular operation. Since the modular operation can realize the boundedness of chaotic state points, it is important to further reveal the deterministic correlation between Lyapunov exponent and modulus. First, we constructed an n -dimensional nondegenerate hyperchaotic map model with the desired Lyapunov exponents. Then, we gave the existence and uniqueness proof of quadrature rectangle decomposition theorem and revealed the correlation between Lyapunov exponent and modulus. The novelty lies in that (1) in order to realize the irreversibility of the iterative processes of chaotic maps, we constructed a chaotic map based on modular exponentiation, and its inverse function is the discrete logarithm problem; and (2) we reveal for the first time the correlation between Lyapunov exponent and modulus, and give the lower bound of the modulus of the nondegenerate chaotic map. In addition, to verify the effectiveness of the scheme, we constructed four-dimensional and five-dimensional chaotic maps, respectively, and analyzed their dynamical behaviors, and the results revealed that there exist linear or nonlinear correlation between Lyapunov exponent and modulus. [ABSTRACT FROM AUTHOR]

The MCrAlY bonding layer alloy was prepared by vacuum melting, and the alloy composition was NiCoCrAlY and NiCoCrAlYHfTa. The high-temperature cyclic oxidation experiment was carried out in air at 1050∘C until it failed. The results show that Hf and Ta have a significant influence on the oxidation resistance of the alloy. The doped specimens have longer oxidation lifetimes compared to the undoped samples. The study also found that the Hf would diffuse out and combine with O to form HfO2 in the thermally grown oxide (TGO) layer, which would improve the adhesion and reduce the wrinkles of the oxide layer. Ta in the doped specimens hinders the diffusion of Al and reduces the oxidation rate, while improving the thermal mismatch. Therefore, the specimens doped with both Hf and Ta have the highest oxidation lifetimes, though the oxidation lifetime was 10 times longer than that of the undoped specimens. It is indicated that the doping of Hf and Ta is an important method to improve the oxidation lifetime of thermal barrier coatings (TBCs). [ABSTRACT FROM AUTHOR]

Polymer Nanocomposites (PNC) comprising polyvinylidene fluoride (PVDF)/Multi-walled Carbon Nanotubes (MWCNT) were studied. The structural composition and thermal stability were confirmed from XRD and DSC/TGA data, respectively. The extent of distribution of MWCNT in the PNC increases and the clustering of MWCNT also increases with an increase in the volume fraction of MWCNT ( f MWCNT ) , as confirmed by FESEM. The PNC shows an insulator-to-metal transition (IMT), with both non-universal percolation threshold (f c) of f MWCNT = 0. 0 0 6 and scaling exponents [ s = 0. 3 6 ± 0. 0 3 , s ′ = 1. 2 6 ± 0. 1 ] , respectively, attributed to adhesiveness/cold pressing and the higher aspect ratio/conductivity of MWCNT. Modulus spectroscopy confirms a non-Debye type universal relaxation behavior (β = 0. 5 4) only for the percolative sample due to Maxwell–Wagner–Sillars/interfacial polarization, while only dipolar relaxation was probed or the samples below f c . The f c with static effective dielectric constant ∼ 2 1 1 and low tan δ may be suitable for charge storage applications. [ABSTRACT FROM AUTHOR]

Polycrystalline Na 0. 9 Ba 0. 1 Nb 0. 9 ( Sn 0. 5 Ti 0. 5 ) 0. 1 O3 is prepared by the solid-state reaction technique. The formation of single-phase material was confirmed by an X-ray diffraction study and it was found to be a tetragonal phase at room temperature. Nyquist plots ( Z ′ ′ versus Z ′) show that the conductivity behavior is accurately represented by an equivalent circuit model which consists of a parallel combination of bulk resistance and constant phase elements (CPE). The frequency dependence of the conductivity is interpreted in terms of Jonscher's law. The conductivity σ d c follows the Arrhenius relation. The modulus plots can be characterized by the empirical Kohlrausch–Williams–Watts (KWW), φ (t) = exp(− (t / τ) β) function and the value of the stretched exponent (β) is found to be almost independent of temperature. The near value of activation energies obtained from the analyses of modulus and conductivity data confirms that the transport is through an ion hopping mechanism dominated by the motion of the ( O 2 −) ions in the structure of the investigated material. [ABSTRACT FROM AUTHOR]

The objective of this work is to develop a first level approximation hybrid model that predicts the rate of reduction of the elastic modulus for a composite internal fixation plate. The first level model combines a modified composite theory in which the bioresorbable constituent moduli and volume fractions are time-dependent, with predictions from a Finite Element (FE) model, but ignores viscoelastic effects. The FE model is used to predict relationships between geometrical constraints (material interfaces), while a theoretical combined elastic modulus is determined using the Reuss model. The composite internal fixation device design comprises Poly-L-lactide and Hydroxyapatite (HA/PLLA) and Titanium. The geometrical relationships established by the FE static model are combined with the theoretical mathematical model in order to predict the rate of decrease of the elastic modulus of the composite device. The first level model predicts that the composite plate modulus decreases at a rate that appropriately compensates for the increasing modulus of the healing bone during fracture healing. This suggests that the proposed composite fixation plate has a strong potential for improved fracture healing through the reduction of stress shielding while the fracture heals, and the elimination of stress shielding after fracture healing. [ABSTRACT FROM AUTHOR]

A Reversible Data Hiding technique by using histogram shifting and modulus operator is proposed in which secret data is embedded into blocks of the cover image. These blocks are modified by using modulus operator to increase the number of peak points in the histogram of the cover image which further increases its embedding capacity. Secret data is embedded in the original cover blocks of the cover image by using peak points of the predicted blocks, which are generated by using modulus operator. Peak Signal to Noise Ratio and PSNR-Human Visual System are used to show the human visual acceptance of the proposed technique. Experimental results show that the embedding capacity is high as compared to the capacity of existing RDH techniques, while distortion in marked images is also less as compared to distortion produced by these existing techniques. [ABSTRACT FROM AUTHOR]

Frequency dividers are used in frequency synthesizers to generate specific frequencies or clock (CK) waveforms. As consequences of their operating principles, frequency dividers often produce output waveforms that exhibit duty cycles other than 50%. However, some circuits and systems, including dynamic memory systems and data converters, which accommodate frequency divider outputs, may need symmetric or 50%-duty-cycle clock waveforms to optimize timing margins or to obtain sufficient timing reliability. In this review paper, design principles and methods are studied to produce symmetric waveforms for the in-phase (I) and quadrature (Q) outputs of high-speed CMOS frequency dividers with design considerations from the logic gate level down to the transistor level in terms of speed, reliability, noise, and latency. A compact and robust multi-gigahertz frequency divider with moduli 12, 14, and 16 to provide I and Q outputs with 50% duty cycle is proposed and designed using a 90-nm digital CMOS process technology with 1.2-V supply. [ABSTRACT FROM AUTHOR]

The effects of oxidation on the weight change (DW) and modulus change (DE) of an uncoated C/SiBC were investigated in 600–1000°C. The results show that larger DW does not mean larger damage. DE is more sensitive to the oxidation process than DW. At lower temperatures, a small DW can result in a large DE. The results result from the different oxidation rates of carbon fibers and pyrocarbon interphase. [ABSTRACT FROM AUTHOR]

In this investigation, the mechanical and thermal properties of the montmorillonite-epoxy nanocomposites were studied. The epoxy compounds were prepared by in situ polymerization and the intercalation dispersion were obtained as evidenced using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results reveal remarkable stiffening effect and slight toughening effect of the MMT in the epoxy resin and an insight about the crack tip and notch tip toughening mechanism. According to the DMA, the glass transition temperature increases as increasing the MMT content. [ABSTRACT FROM AUTHOR]

This paper presents two kinds of magnetorheological elastomers (MREs). One is composed of appropriate silicon rubber, carbonyl iron particles and some other materials. It is cured under a strong magnetic field at a room temperature. Its shear modulus change from 0.34MPa at zero magnetic field to 3.34MPa at 1T magnetic field, the relative MR effect reaches 878%. Such high MR effect has not been reported until now. The other is composed by appropriate natural rubber, carbonyl iron particles and some other materials. After the compositions are mixed in a two-roll mill, they are cured under a strong magnetic field according to a temperature profile. The increment of its modulus reaches 3.6MPa, and the relative modulus increment is 133%. Their mechanical properties are also evaluated. All observed results show that the fabricated MREs are utilizable. They have successfully been utilized to adaptive tuned vibration absorbers, which will serve for vibration absorption of vehicles. [ABSTRACT FROM AUTHOR]

The micro- and nano-indentation techniques and compression tests were employed to determine the mechanical properties of PZT based composites dispersed with Al2O3 nano-particles for comparison. Compared with the reduced modulus, the nano-hardness, which exhibited indentation size effect (ISE), seemed to be more sensitive to the indentation depth. The true hardness values were deduced, based on the modified proportional specimen resistance (PSR) model, from the depth sensing machine and micro-indenter. Both the micro- and nano-hardness of the nano-composites confirmed that the hardness was best improved by addition of 0.5wt% of Al2O3. [ABSTRACT FROM AUTHOR]

A major concern when a fractured bone is fastened by stiff-plates to the bone on its tensile surface is excessive stress shielding of the bone. The compressive stress shielding at the fracture-interface immediately after fracture-fixation delays bone healing. Likewise, the tensile stress shielding of the healed bone underneath the plate also does not enable it to recover its tensile strength. Initially, the effect of a uniaxial load and a bending moment on the assembly of bone and plate is investigated analytically. The calculations showed that the screws near the fracture site transfers more load than the screws away from the fracture site in axial loading and it is found that less force is required when the screw is placed near to fracture site than the screw placed away from the fracture site to make the bone and plate bend with same radius of curvature when subjected to bending moment. Finally, the viability of using a stiffness graded bone-plate as a fixator is studied using finite element analysis (FEA): the stiffness-graded plate cause less stress-shielding than stainless steel plate. [ABSTRACT FROM AUTHOR]