Journal of Computational and Theoretical Nanoscience

Discrete nanodiamond particles of 500 nm and 6 nm average size were seeded onto silicon substrates and plasma treated using chemical vapor deposition to create silicon-vacancy color centers. The resulting narrow-band room temperature photoluminescence is intense, and readily observed even for weakly agglomerated sub-10 nm size diamond. This is in contrast to the well-studied nitrogen-vacancy center in diamond which has luminescence properties that are strongly dependant on particle size, with low probability for incorporation of centers in sub-10 nm crystals. We suggest the silicon-vacancy center to be a viable alternative to nitrogen-vacancy defects for use as a biomarker in the clinically-relevant sub-10 nm size regime, for which nitrogen defect-related luminescent activity and stability is reportedly poor.

Since the pneumatic system has compressibility and time-delay nonlinearity behaviors, especially, for a heavy-duty pneumatic actuating table, it is difficult to establish an appropriate mathematical model for the design of model-based controller. Although fuzzy logic control has model-free feature, it still needs a time consuming work for rules bank and fuzzy parameters adjustment. Here, a self-adaptation fuzzy controller (SAFC) is proposed to control the up-down motion of a four legs pneumatic actuating table. This intelligent control strategy combines an adaptive rule with fuzzy and sliding mode control algorithms. It has on-line learning ability to deal with the system time-varying and non-linear uncertainty coupling behaviors, and adjust the control rules parameters. Only eleven fuzzy rules are required for this MIMO pneumatic actuating table motion control and these fuzzy control rules can be established and modified continuously by on-line learning. The experimental results show that this intelligent control algorithm can effectively monitor the pneumatic table to track the specified motion trajectories.

The AUV(Autonomous surface vehicle) is widely used for military purpose and scientific purpose. The AUV can save human life from severe environment and reduce the operating cost of underwater equipment. Generally, hulls of AUV are made of composite materials or metal alloys such as aluminum alloy and titanium alloy. Composite materials are well known as its light weight, corrosion resistance and freedom of shape design. But, composite materials are not have plastic deformation so this can be a disadvantage as the materials for underwater equipment. From this reason, this study focused on the reliability of the material. This study contains material design, experiment for materials and verification by FEA. The material what was focused on this study is Al-CFRP hybrid composites. There are used two kinds of Al-CFRP hybrid composites. Inter laminar property between Aluminum alloy and carbon fiber reinforced composites is very important. So, two kinds of Al-CFRP were used for this study. One is co-cured material and the other is post-bonded. Tensile and interlaminar test were achieved to define material properties. Profits from use of Al-CFRP sandwich material are like these. First, this material can enhance the buckling performance and second, it can achieve the reliability against failure at a moment. Mechanical tests are achieved for designed materials and its results are used for FEA. This study verify the feasibility about Al-CFRP hybrid composites for AUVs. The hull of AUV manufacturing and ocean diving test will be achieved in future work.

This paper presents implementation of a carrier-based three-dimensional space vector PWM technique for three-phase four-leg voltage source converter with microcontroller. The implementation of the 3-D SVPWM needs quite a bit of digital logic and computational power, and it might be a software and hardware burden even for recent digital signal processor (DSP) systems. Therefore, this paper presents a simple three-phase four-leg with carrier-based three-dimensional space vector PWM technique. The proposed technique can be implemented with microcontroller. The performance of proposed PWM strategy has been investigated and verified through simulations and experimental results for three-phase four-leg voltage source converter. This proposed method also can be applied to system that needs the synchronization between source voltage and load voltage.

This paper presents an energy-efficient contention based cooperative routing scheme for event detection in wireless sensor networks. In order to improve detection efficiency and diminish energy consumption, ECCRD selects the appropriate relay node by integrated consideration of detection efficiency, access probability and energy consumption. In the scheme, we propose a well-defined cooperative access mechanism which captures the detection capability and is used as the criterion for relay node selection during each contention round. Simulation results show that ECCRD achieves better detection efficiency and less energy consumption.

Web services technology provides a flexible and cost-effective paradigm to construct highly dynamic systems through service discovery, composition, and ultra-late binding. However, its new features bring great pressure to maintain Web service-based system. Based on the massive testing results, how to locate the fault points in system is a challenging task. In the paper, a two level diagnosis framework for Web services system is proposed. In service unit level, the WSDL interface information is used to construct decision table. In service composition level, the decision information system is built by comprehensively using process specifications and interface information. Then, rule mining algorithm in rough set reasoning is adopted to reveal the input cases associated with service or system failures. How to utilize such rules to locate faults in Web services system is also discussed. In addition, two cases are introduced to validate the feasibility and effectiveness of our approach.

A set of basic vectors locally describing metric properties of an arbitrary 2-dimensional (2D) surface is used for construction of fundamental algebraic objects having nilpotent and idempotent properties. It is shown that all possible linear combinations of the objects when multiplied behave as a set of hypercomples (in particular, quaternion) units; thus interior structure of the 3D space dimensions pointed by the vector units is exposed. Geometric representations of elementary surfaces (2D-sells) structuring the dimensions are studied in detail. Established mathematical link between a vector quaternion triad treated as a frame in 3D space and elementary 2D-sells prompts to raise an idea of "world screen" having 1/2 of a space dimension but adequately reflecting kinematical properties of an ensemble of 3D frames.

We derive a quantization formula of Bohr-Sommerfeld type for computing quasinormal frequencies for scalar perturbations in an AdS black hole in the limit of large scalar mass or spatial momentum. We then apply the formula to find poles in retarded Green functions of boundary CFTs on $R^{1,d-1}$ and $RxS^{d-1}$. We find that when the boundary theory is perturbed by an operator of dimension $\Delta>> 1$, the relaxation time back to equilibrium is given at zero momentum by ${1 \over \Delta \pi T} << {1 \over \pi T}$. Turning on a large spatial momentum can significantly increase it. For a generic scalar operator in a CFT on $R^{1,d-1}$, there exists a sequence of poles near the lightcone whose imaginary part scales with momentum as $p^{-{d-2 \over d+2}}$ in the large momentum limit. For a CFT on a sphere $S^{d-1}$ we show that the theory possesses a large number of long-lived quasiparticles whose imaginary part is exponentially small in momentum.

Flower-like nanostructures formed by ZnO nanorods were synthesized and deposited on seeded silicon and glass substrates by a hexamethylenetetramine (HMTA) - assisted hydrothermal method at low temperature (90 oC) with methenamine ((CH3)6N4), as surfactant and catalyst. The substrates were seeded with ZnO nanoparticles. The structure and morphology of the nanostructures were studied by means of x-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM) techniques. Influence of the seed nanoparticle on the formation of the flower-like ZnO nanostructures is demonstrated. The influence of the organic oxygenated chains on the crystalline habit during the growth process is also observed.

Asteroids are leftover pieces from the era of planet formation that help us understand conditions in the early Solar System. Unlike larger planetary bodies that were subject to global thermal modification during and subsequent to their formation, these small bodies have kept at least some unmodified primordial material from the solar nebula. However, the structural properties of asteroids have been modified considerably since their formation. Thus, we can find among them a great variety of physical configurations and dynamical histories. In fact, with only a few possible exceptions, all asteroids have been modified or completely disrupted many times during the age of the Solar System. This picture is supported by data from space mission encounters with asteroids that show much diversity of shape, bulk density, surface morphology, and other features. Moreover, the gravitational attraction of these bodies is so small that some physical processes occur in a manner far removed from our common experience on Earth. Thus, each visit to a small body has generated as many questions as it has answered. In this review we discuss the current state of research into asteroid disruption processes, focusing on collisional and rotational mechanisms. We find that recent advances in modeling catastrophic disruption by collisions have provided important insights into asteroid internal structures and a deeper understanding of asteroid families. Rotational disruption, by tidal encounters or thermal effects, is responsible for altering many smaller asteroids, and is at the origin of many binary asteroids and oddly shaped bodies. Comment: Accepted for publication to Advanced Science Letters, Special Issue on Computational Astrophysics, edited by Lucio Mayer

Experimental tests of Bell's inequality allow to distinguish quantum mechanics from local hidden variable theories. Such tests are performed by measuring correlations of two entangled particles (e.g. polarization of photons or spins of atoms). In order to constitute conclusive evidence, two conditions have to be satisfied. First, strict separation of the measurement events in the sense of special relativity is required ("locality loophole"). Second, almost all entangled pairs have to be detected (for particles in a maximally entangled state the required detector efficiency is 82.8%), which is hard to achieve experimentally ("detection loophole"). By using the recently demonstrated entanglement between single trapped atoms and single photons it becomes possible to entangle two atoms at a large distance via entanglement swapping. Combining the high detection efficiency achieved with atoms with the space-like separation of the atomic state detection events, both loopholes can be closed within the same experiment. In this paper we present estimations based on current experimental achievements which show that such an experiment is feasible in future.

Several scenarios have been proposed in which primordial perturbations could originate from quantum vacuum fluctuations in a phase corresponding to a collapse phase (in an Einstein frame) preceding the Big Bang. I briefly review three models which could produce scale-invariant spectra during collapse: (1) curvature perturbations during pressureless collapse, (2) axion field perturbations in a pre big bang scenario, and (3) tachyonic fields during multiple-field ekpyrotic collapse. In the separate universes picture one can derive generalised perturbation equations to describe the evolution of large scale perturbations through a semi-classical bounce, assuming a large-scale limit in which inhomogeneous perturbations can be described by locally homogeneous patches. For adiabatic perturbations there exists a conserved curvature perturbation on large scales, but isocurvature perturbations can change the curvature perturbation through the non-adiabatic pressure perturbation on large scales. Different models for the origin of large scale structure lead to different observational predictions, including gravitational waves and non-Gaussianity.

We study the gravitational collapse of an inhomogeneous scalar field with quantum gravity corrections associated with singularity avoidance. Numerical simulations indicate that there is critical behaviour at the onset of black hole formation as in the classical theory, but with the difference that black holes form with a mass gap. Comment: 8 pages, 3 figures. Typos corrected -- version to appear in a special issue of Adv. Science Lett. (Ed. M. Bojowald)

Binary black holes occupy a special place in our quest for understanding the evolution of galaxies along cosmic history. If massive black holes grow at the center of (pre-)galactic structures that experience a sequence of merger episodes, then dual black holes form as inescapable outcome of galaxy assembly. But, if the black holes reach coalescence, then they become the loudest sources of gravitational waves ever in the universe. Nature seems to provide a pathway for the formation of these exotic binaries, and a number of key questions need to be addressed: How do massive black holes pair in a merger? Depending on the properties of the underlying galaxies, do black holes always form a close Keplerian binary? If a binary forms, does hardening proceed down to the domain controlled by gravitational wave back reaction? What is the role played by gas and/or stars in braking the black holes, and on which timescale does coalescence occur? Can the black holes accrete on flight and shine during their pathway to coalescence? N-Body/hydrodynamical codes have proven to be vital tools for studying their evolution, and progress in this field is expected to grow rapidly in the effort to describe, in full realism, the physics of stars and gas around the black holes, starting from the cosmological large scale of a merger. If detected in the new window provided by the upcoming gravitational wave experiments, binary black holes will provide a deep view into the process of hierarchical clustering which is at the heart of the current paradigm of galaxy formation. They will also be exquisite probes for testing General Relativity, as the theory of gravity. The waveforms emitted during the inspiral, coalescence and ring-down phase carry in their shape the sign of a dynamically evolving space-time and the proof of the existence of an horizon. Comment: Invited Review to appear on Advanced Science Letters (ASL), Special Issue on Computational Astrophysics, edited by Lucio Mayer

The knowledge of the density matrix of a quantum state plays a fundamental role in several fields ranging from quantum information processing to experiments on foundations of quantum mechanics and quantum optics. Recently, a method has been suggested and implemented in order to obtain the reconstruction of the diagonal elements of the density matrix exploiting the information achievable with realistic on/off detectors, e.g. silicon avalanche photo-diodes, only able to discriminate the presence or the absence of light. The purpose of this paper is to provide an overview of the theoretical and experimental developments of the on/off method, including its extension to the reconstruction of the whole density matrix. Comment: revised version, 11 pages, 6 figures, to appear as a review paper on Adv. Science Lett

We offer a theoretical design of new systems that show promise for digital biochemical computing, including realizations of error correction by utilizing redundancy, as well as signal rectification. The approach includes information processing using encoded DNA sequences, DNAzyme biocatalyzed reactions and the use of DNA-functionalized magnetic nanoparticles. Digital XOR and NAND logic gates and copying (fanout) are designed using the same components.

Black holes in equilibrium and the counting of their entropy within Loop Quantum Gravity are reviewed. In particular, we focus on the conceptual setting of the formalism, briefly summarizing the main results of the classical formalism and its quantization. We then focus on recent results for small, Planck scale, black holes, where new structures have been shown to arise, in particular an effective quantization of the entropy. We discuss recent results that employ in a very effective manner results from number theory, providing a complete solution to the counting of black hole entropy. We end with some comments on other approaches that are motivated by loop quantum gravity.

This is a review of current theory of black-hole dynamics, concentrating on the framework in terms of trapping horizons. Summaries are given of the history, the classical theory of black holes, the defining ideas of dynamical black holes, the basic laws, conservation laws for energy and angular momentum, other physical quantities and the limit of local equilibrium. Some new material concerns how processes such as black-hole evaporation and coalescence might be described by a single trapping horizon which manifests temporally as separate horizons.

Arguments are presented to show that in the case of entangled systems there are certain difficulties in implementing the usual Bohmian interpretation of the wave function in a straightforward manner. Specific examples are given.

We theoretically demonstrate that detectors endowed with internal gain and operated in regimes in which they do not necessarily behave as photon-counters, but still ensure linear input/output responses, can allow a self-consistent characterization of the statistics of the number of detected photons without need of knowing their gain. We present experiments performed with a photo-emissive hybrid detector on a number of classical fields endowed with non-trivial statistics and show that the method works for both microscopic and mesoscopic photon numbers. The obtained detected-photon probability distributions agree with those expected for the photon numbers, which are also reconstructed by an independent method.

We construct the most general perturbatively long-range integrable spin chain with spins transforming in the fundamental representation of gl(N) and open boundary conditions. In addition to the previously determined bulk moduli we find a new set of parameters determining the reflection phase shift. We also consider finite-size contributions and comment on their determination.

Different procedures have been developed in order to recover entanglement after propagation over a noisy channel. Besides a certain amount of noise, entanglement is completely lost and the channel is called entanglement breaking. Here we investigate both theoretically and experimentally an entanglement concentration protocol for a mixed three-qubit state outgoing from a strong linear coupling of two-qubit maximally entangled polarization state with another qubit in a completely mixed state. Thanks to such concentration procedure, the initial entanglement can be probabilistically recovered. Furthermore, we analyse the case of sequential linear couplings with many depolarized photons showing that thanks to the concentration a full recovering of entanglement is still possible. Comment: 16 pages, 7 figures, to be published on Advanced Science Letters

We suggest to use the photon homodyne detection experimental data for checking the Heisenberg and Schr\"{o}dinger-Robertson uncertainty relations, by means of measuring optical tomograms of the photon quantum states.

The MPB composition, Na0.88Li0.12NbO3 (commonly known as LNN-12) has been synthesized by adopting recently developed low-cost citrate-gel route where Nb2O5 acts as a source of Nb. During synthesis, Nb2O5 transforms into a stable and soluble chelate complex, an alternative of expensive metal alkoxides. Thermal decomposition process and phase formation of the as prepared gel were studied using thermo-gravimetry (TG) and X-ray diffractometry (XRD). The gels were calcined in the temperature range 500–800 °C and a pure perovskite phase was obtained at 700 °C, which is 200 °C below the conventional ceramics route (900 °C). Morphology of the phase pure powders was characterized using scanning electron microscopy (SEM) and highresolution transmission electron microscopy (HRTEM). The compacted samples showed high sintered density at < 1200 °C. This has been attributed to small particle size and homogeneity. The lower sintering temperature eliminates the possibility of alkali elements loss, leading to exact MPB composition and enhancement in the electrical properties.

According to the inflationary scenario of cosmology, all structure in the Universe can be traced back to primordial fluctuations during an accelerated (inflationary) phase of the very early Universe. A conceptual problem arises due to the fact that the primordial fluctuations are quantum, while the standard scenario of structure formation deals with classical fluctuations. In this essay we present a concise summary of the physics describing the quantum-to-classical transition. We first discuss the observational indistinguishability between classical and quantum correlation functions in the closed system approach (pragmatic view). We then present the open system approach with environment-induced decoherence. We finally discuss the question of the fluctuations' entropy for which, in principle, the concrete mechanism leading to decoherence possesses observational relevance. Comment: 12 pages, Revtex, invited contribution to a special issue of Advanced Science Letters, final version