Automatic locking of a parametrically resonating,base-excited,nonlinear beam

Nonlinear Dynamics - Described is a closed-loop control scheme capable of stabilizing a parametrically excited nonlinear structure in several vibration modes. By setting the relative phase between...     

Construction and studies of a new class of reciprocal trees: interknitting of the Pascal's triangle

A method of construction of a new class of trees with reciprocal pairs of eigenvalues (λ, 1/λ) has been developed. They are derived from star graphs and can be symbolized as K _{1, n ?1} + n(p) + mK ₂ (1 ≤ m ≤ n ? 1 except for n = 1). The trees are minimally Kekulenoid and hence contain reciprocal pairs of eigenvalues in their eigenspectra. The characteristic polynomial coefficients of these trees with given values of n and m are shown to be obtainable by appropriate use of the Pascal's triangle. A general formula for this purpose has been developed. An analytical formula for the Wiener indices of such trees in terms of m and n has been derived and some consequences of this formula are presented. The relevance of these trees to real molecular structures is discussed. The trees have been shown to be useful in observing the subspectrallity of two series of IPR fullerenes of formulae C_{50+10 n} and C_{60+12 n} (n is a positive integer).     

Calculation of cladding modes using both two layer and three layer geometry in LPFG

In this paper we have calculated cladding modes of long period fiber grating. We have calculated cladding modes using both two layer (Graphical solution method) geometry and three layer geometry proposed by Erdogan. We have compared both these techniques, discussed the limitations of Graphical solution method and benefits of three layer geometry.     

An optimal protection and restoration scheme (OPARS) for optical networks

Protection and restoration are critical network design issues for optical networks since even a single failure for a short duration may result in huge data loss due to the large capacity of optical fibers. However, few studies have been done on these issues for optical burst switching (OBS) networks. Protection and restoration are essential mechanisms for guaranteeing more reliable traffic delivery services. But it is not easy to apply existing mechanisms to optical burst switching (OBS) networks due to its one-way reservation signaling and the statistical burst multiplexing. Thus, to achieve the high transmission performance and reliability simultaneously, unique properties of OBS must be considered in the design of protection scheme. In this paper, an optimal protection and restoration scheme (OPARS) has been introduced that not only optimizes the number of provisioned protection wavelengths adaptively based on the traffic load as well as the quality of service (QoS) requirements of bursts in high speed networks but also minimizes burst loss rates. In addition, the proposed scheme has been used as an efficient contention resolution technique. The simulation results verify that the proposed scheme improve the network resource and channel utilization while guaranteeing the targeted protection reliability and QoS requirements of bursts.     

Gold‐Nanoparticle‐Decorated Boron Nitride Nanosheets: Structure and Optical Properties

Synergetic cooperation of individual components of the nanocomposites (NCs) is responsible for their novel properties that lead to various technological applications. A simple chemical process depicting the deposition of functionalized gold nanoparticles on the surface of boron nitride nanosheets (BNNSs) in solution is reported. The structure, chemical composition, and optical properties of nanosheets are systematically studied. The deposition of Au nanoparticles on BNNS (BNNS_Au) results in plasmonic band modulation, thus altering the optoelectronic properties of BNNSs. The intense surface plasmon absorption band of BNNS_Au is narrowed and red‐shifted relative to the absorption band of as synthesized monometallic BNNSs. The observations reflect the strong interfacial interaction between BNNS and Au nanoparticles. This approach constitutes a basis for a simple process leading to the preparation of functionalized BNNSs and their utilization as nanoscale templates for assembly and integration with other nanoscale materials for futuristic optoelectronic devices.     

Surface Coating Rescues Proteins from Magnetite Nanoparticle Induced Damage

The presence of magnetic nanoparticles (NPs) in physiological systems induces toxicity through its effects on mitochondrial function and reactive oxygen species (ROS) imbalance. Magnetic NP induced cytotoxicity has been elaborately evaluated for impending threats, however, a detailed investigation is lacking. It is shown that the interaction of Fe₃O₄ NPs with cytochrome c can lead to different events based on the NPs to protein ratio, the solution conditions, and the type of surface protection. At low NPs concentration, rapid binding and subsequent electron transfer are the preferred events while at higher concentration slow oxidative modification of the protein is initiated. The slow event of protein modification yields conformational disorientation, loss of stability, and formation of amyloid‐like structures with cytochrome c. The possibility that the NP induced oxidative stress and age can work in concert to compromise different aspects of cellular quality control processes is discussed. Suitable surface modifications of the NPs inhibit their direct binding to the protein molecules and minimize NP induced toxicity.     

Structure property correlations in alcohols through two-photon absorption cross-section measurements

Two-photon absorption (TPA) cross-sections of neat alcohols are shown to be a femtosecond laser measurable property with useful structure property correlations that are directly correlated to the self-phase modulation of the alcohol in question. The amount of self-phase modulation is shown to be a molecular structure dependent property. The real and the imaginary components of the second-order hyperpolarizability are thus shown to be interrelated. Such TPA measurements prove that it is not possible to predict two-photon absorption properties by simple doubling the wavelengths of one-photon absorption spectra.     

Synthesis and structural characterisation of new Re(III) complexes using aldimines of α-amino acids as coligands

Complexes of the general formula [Re^III(L)Cl(PPh₃)₂] have been synthesised by reacting H₂L and [ReOCl₃(PPh₃)₂] in ethanol. Here H₂L represents imines of α-amino acids (glycine, l-alanine, l-valine, l-phenylalanine) derived from salicylaldehyde and naphthaldehyde. The crystal structure of one complex has been determined. The complexes are mononuclear, paramagnetic and display paramagnetic ¹H NMR in CDCl₃ solution. Their spectral and redox properties are scrutinised.     

Fast intersections on nested tetrahedrons (FINT): An algorithm for adaptive finite element based distributed parameter estimation

A variety of biomedical imaging techniques such as optical and fluorescence tomography, electrical impedance tomography, and ultrasound imaging can be cast as inverse problems, wherein image reconstruction involves the estimation of spatially distributed parameter(s) of the PDE system describing the physics of the imaging process. Finite element discretization of imaged domain with tetrahedral elements is a popular way of solving the forward and inverse imaging problems on complicated geometries. A dual-adaptive mesh-based approach wherein, one mesh is used for solving the forward imaging problem and the other mesh used for iteratively estimating the unknown distributed parameter, can result in high resolution image reconstruction at minimum computation effort, if both the meshes are allowed to adapt independently. Till date, no efficient method has been reported to identify and resolve intersection between tetrahedrons in independently refined or coarsened dual meshes. Herein, we report a fast and robust algorithm to identify and resolve intersection of tetrahedrons within nested dual meshes generated by 8-similar subtetrahedron subdivision scheme. The algorithm exploits finite element weight functions and gives rise to a set of weight functions on each vertex of disjoint tetrahedron pieces that completely cover up the intersection region of two tetrahedrons. The procedure enables fully adaptive tetrahedral finite elements by supporting independent refinement and coarsening of each individual mesh while preserving fast identification and resolution of intersection. The computational efficiency of the algorithm is demonstrated by diffuse photon density wave solutions obtained from a single- and a dual-mesh, and by reconstructing a fluorescent inclusion in simulated phantom from boundary frequency domain fluorescence measurements.     

Phase transition in triglycine family of hydrogen bonded ferroelectrics: An interpretation based on structural studies

Using the crystal structure, a comprehensive interpretation of the origin of ferroelectricity in the hydrogen bonded triglycine family of crystals is given. Our detailed analysis showed that the instability of nitrogen double well potential plays a driving role in the mechanism of the ferroelectric transitions in these crystals.