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Capacity crunch has become critical in recent years as commercial communication systems approach their theoretical data rate limits. This work presents a low‐complexity digital backpropagation (DBP) implementation approach based on step size distribution that uses a binary logarithmic step size method to achieve high data rate optical transmission. The proposed scheme shows performance improvements (∆Q) of 2.36, 1.19, and 0.71 dB over linear compensation, constant step size (CSS) DBP, and logarithmic step size DBP techniques in a 2400 km 112 Gbit/s DP‐16 quadrature amplitude modulation (QAM) system, respectively. At 13 dBm, a high performance (Q) of 10.9 dB (BER = 2.25 × 10−4) is achieved, above the 3.80 × 10−3 hard‐decision forward error correction (HD‐FEC) limit, using the proposed scheme. Also, the allowable transmission distance is extended by 960 km at the HD‐FEC limit over the linear compensation technique. The optimization achieves a 38% saving in the number of DBP calculation steps compared to the CSS DBP, which considerably reduces the computational cost since a few steps are required for effective non‐linearity compensation. [ABSTRACT FROM AUTHOR]

The hybrid beamforming can significantly improve the spectral and energy efficiencies of the millimeter‐wave (mmWave) massive multiple input multiple output (MIMO) systems without obvious performance loss. However, the fundamental limitation of existing hybrid beamforming is that they include high‐resolution analog‐to‐digital converters (ADCs) which consume high power. To overcome this fundamental limitation, in this paper, spectrum and energy efficient mmWave massive MIMO transmission scheme is proposed that jointly optimizes the hybrid combiner and the number of ADC bits. Particularly, the hybrid combiner is presented as a combination of three parts: the analog combiner matrix, the quantization matrix, and the digital baseband matrix which is based on the Kalman filter. Unlike most existing works that rely on sumrate optimization to design the hybrid combiner, in this work, the mean square error (MSE) is chosen as the main performance metric to describe the reliability of the system. Simulations results confirm that the proposed Kalman based hybrid combiner exhibits the best performance in terms of spectral and energy efficiencies compared to minimum mean square error (MMSE) and zero forcing (ZF) receivers. [ABSTRACT FROM AUTHOR]

Efficient quantizer design is vital in high‐speed optical receivers. In this paper, the authors propose a three‐level (1.5‐bit) reliability‐based quantizer for low‐complexity soft decoding of low‐density parity‐check (LDPC) codes, and show that it outperforms a conventional quantizer employing eight levels (3 bits). Different approaches for obtaining the quantization thresholds are discussed, and it is shown that the achievable channel capacity with the proposed quantizer is within 0.4 dB of the Shannon limit of the unquantized channel. Rate‐compatible LDPC codes are also designed tailored to the asymmetric optical channel terminated with the proposed reliability‐based quantizer, and it is shown that the resulting quantizer‐aware LDPC codes significantly outperform other existing codes of similar rates. [ABSTRACT FROM AUTHOR]

This study investigates the quantised-input FIR (finite impulse response) system identification under quantised and event-triggered output observations. For the binary-valued quantisation, they introduce a so-called either-or communication scheme to save communication resources. Based on the received data and the triggered indicator, an identification algorithm is proposed to estimate the unknown parameter by use of the empirical measure and weighted least squares. The convergence performance is established and the communication rate is derived. For the multi-threshold quantisation, it can be seen as a vector-valued observation in which each component represents a binary-valued output, and the corresponding identification problem is discussed. A numerical example is included to illustrate the main results obtained. [ABSTRACT FROM AUTHOR]

A new quantizing technology scheme of insulator soldering was presented comparing with traditional soldering technology using solder paste, based on utilization of solid solder ring and the consideration of insulator mounting hole design on the microwave module shell. The X‐ray test on void ratio of insulator soldering shows that there exists no penetration void and the void ratio is below 5%. According to the leak standard A4 of GJB 548B‐1014.2, the standard leak rate of microwave module after the insulator soldering was below 5 × 10−9(Pa·m3)/s. After 10 cycles of temperature shock test ranging from −55°C to 125°C, the standard leak rate of microwave module was still below 5 × 10−9 (Pa·m3)/s. In comparison with traditional insulator soldering technology using solder paste, through utilization of solid solder ring and the design of insulator mounting hole, this new technology quantized the soldering of insulator so as to resolve the existing defects of traditional insulator soldering such as solder overflow, high void ratio, shortcut and channel blocking. The quantized insulator sealed soldering technology ensured the reliability, air impermeability, uniformity and beautifulness of soldering meanwhile improved operators' efficiency. [ABSTRACT FROM AUTHOR]

In this work, a facile chemical route is presented to prepare photoluminescent MoS2 quantum dots (QDs) and nanosheets (NSs) on a large‐scale. The strategy involves probe‐type sonication of bulk MoS2 sheets in ethanol/water mixture followed by refluxing in dimethylformamide (DMF) solution. This preparation route makes cleavage of the Van‐der‐Waal layers possible by exfoliation across the 2D planes and the complete breakup of bulk MoS2 sheets around the defects and edges. The as‐prepared MoS2 QDs and NSs exhibit size quantization effects in their optical absorption and emission spectra. The resultant MoS2 NSs consist of few layers with lateral size around ∼80 nm and exhibit excitation dependent blue emission. Whereas, most of the MoS2 QDs were measured around ∼4.8 nm in lateral size and showed distinct green emission upon excitation. This may be attributed to a combined contribution from the increase in the quantum‐sized core, edge defects, dangling bonds, and surface states recombination. The study thus provides a simple pathway for the preparation of monolayer QDs and few‐layer NSs of transition‐metal‐dichalcogenides (TMD) or other layered materials. MoS2 quantum dots (QDs) and nanosheets (NSs) were prepared through a simple two‐step chemical route; probe‐type sonication of bulk MoS2 sheets in ethanol/water mixture followed by refluxing in DMF. The as‐prepared MoS2 QDs and NSs with lateral size around ∼80 nm and ∼4.8 nm, respectively, exhibit size quantization effects with excitation dependent blue and green emissions. [ABSTRACT FROM AUTHOR]

Summary: This paper studies the fault estimation problem for a class of nonlinear semi‐Markovian jump systems with partly unknown transition rates and output quantization. Firstly, a mode‐dependent intermediate variable is designed, which constructs an intermediate estimator to estimate fault signals of system. Secondly, the partly unknown transition rates and output quantization are considered and the sufficient conditions of stability for the error system are given in three cases by linear matrix inequalities. Moreover, the proposed nonlinear function satisfies Lipschitz condition, which can be employed in a multitude of practical systems. Finally, simulation results are provided to illustrate the effectiveness of the proposed theoretical results. [ABSTRACT FROM AUTHOR]

Sampled-data based quantisation control for Takagi-Sugeno (T-S) fuzzy switched systems with actuator failures under asynchronous switching is studied. By the T-S fuzzy model, sampled-data based asynchronous control is extended into switched non-linear systems. An improved functional method is introduced. Applying this method, improved Lyapunov functionals are constructed. These functionals are mode dependent and piecewise continuous; not every term of these functionals is required to be positive definite; sampling states at both sides of sampling intervals are introduced into these functionals. More useful information with respect to system states is reflected in constructing functionals. Combining these functionals with the averaged dwell time technique, stabilisation conditions are relaxed, and improved exponential stabilisation criteria are obtained with less conservatism. In addition, variation ranges of membership functions are taken into account to reduce conservatism. Then, a sampled-data based fuzzy quantisation controller is designed. Simulation examples are given to illustrate the effectiveness of the proposed results. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we discuss quantization effects in rigid formation control systems when target formations are described by interagent distances. Because of practical sensing and measurement constraints, we consider in this paper distance measurements in their quantized forms. We show that under gradient‐based formation control, in the case of uniform quantization, the distance errors converge locally to a bounded set whose size depends on the quantization error, while in the case of logarithmic quantization, all distance errors converge locally to zero. A special quantizer involving the signum function is then considered with which all agents can only measure coarse distances in terms of binary information. In this case, the formation converges locally to a target formation within a finite time. Lastly, we discuss the effect of asymmetric uniform quantization on rigid formation control. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of finding an optimal random dither quantizer for quantized control of positive systems. We show that the random dither quantizer with a uniform distribution is optimal and demonstrate it by a numerical simulation. [ABSTRACT FROM AUTHOR]

Abstract: Single atom and molecule junctions are key components of future ultra‐small electronic devices. The novel properties and functionalities appear in the single atom and molecule junctions reflecting their unique structures. The conductance quantization and quantum interface effects have been reported. In this review, we discuss fabrication and electronic properties of the single atom and molecule junctions, including electrical conductance and thermopower. The single atom and molecule junctions are fabricated in a nanogap prepared by electron migration, self‐breaking and mechanical breaking of metal wires. The electric conductance of the single atom and molecule junctions depends not only the atom and molecule within the junctions, but also on their connectivity to the metal wires at the interface. The conductance fluctuation characteristic of single‐molecule junction reflects the character of the metal‐molecular bond at the interface, which enables us to study the molecular adsorption process during the formation of the junction. [ABSTRACT FROM AUTHOR]

The theory of electron energy quantization in an N atom long chain affected by a homogeneous electric field E e is extended to the 2D case of N atom long and N atom wide conductor with the lattice constant a. The conductor is modeled by the standard one‐parameter tight‐binding Hamiltonian (hopping integral t) of an atomic rectangular square lattice, where the change of electron site energy from atom to atom across the conductor equals (in | t | units) to electric field parameter a e E e / | t | (efp). Each field‐provoked level E μ (transverse μ‐mode energy) is shown giving rise to the μth subband of field‐independent levels of extended states due to the electron resonant transfer in the longitudinal direction perpendicular to the electric field. The level spacing and, hence, the width of μ subbands, is dictated by the conductor width and hopping integral t. The spectra of arbitrary‐size atomic square lattices are classified in terms of subband center spacing (SBCS) within the transverse‐mode bands of extended states, edge‐localized states, and Wannier–Stark states. We identified special cases of integer and fractional SBCS quantization in efp‐portions and found the exact and/or highly accurate explicit approximate expressions for the weighted number of states within these bands. The presented novel results clarify and correct their analogs reported previously. [ABSTRACT FROM AUTHOR]

Abstract: A fundamental problem regarding the Dirac quantization of a free particle on an N − 1 ( N ≥ 2) curved hypersurface embedded in N flat space is the impossibility to give the same form of the curvature‐induced quantum potential, the geometric potential as commonly called, as that given by the Schrödinger equation method where the particle moves in a region confined by a thin‐layer sandwiching the surface. This problem is resolved by means of a previously proposed scheme that hypothesizes a simultaneous quantization of positions, momenta, and Hamiltonian, among which the operator‐ordering‐free section is identified and is then found sufficient to lead to the expected form of geometric potential. [ABSTRACT FROM AUTHOR]

In the present article, alternatives to impurity doping in nanoscale field‐effect transistors (FETs) are investigated. The discussion is based on conventional and tunnel FETs. The impact of dopant deactivation due to dielectric mismatch or quantization, random dopant effects, and the degeneracy level on the performance is discussed. As alternatives metal‐semiconductor‐contacts, gate‐controlled doping and an interface engineering approach are studied. One of the main requirements for proper device functionality is the existence of a band gap in the contacts. Thus, metal‐semiconductor contacts are less suited since they lead to ambipolar operation with increased leakage and to a deteriorated on‐state performance. With gate‐controlled doping, electrodes areused to create doped regions leaving behind a pristine band gap. Moreover, it enables reconfigurable devices with nFET, pFET and tunnel FET operation. Furthermore, with multiple nanoscale gates, electrostatic doping allows manipulating the potential within the device on the nanoscale. Experimental demonstrations of such devices with triple‐gates and multiple gate structures are presented. Finally, the interface engineering approach allows combining a metallic contact electrode with an almost unmodified band gap in the source/drain contacts by adjusting an ultrathin insulator in‐between metal and semiconductor yielding quasi‐doped contacts whose polarity depends on the work function of contact metal. [ABSTRACT FROM AUTHOR]

In this paper, we develop the main ideas of the quantized version of affinely rigid (homogeneously deformable) motion. We base our consideration on the usual Schrödinger formulation of quantum mechanics in the configuration manifold, which is given, in our case, by the affine group or equivalently by the semi-direct product of the linear group [ABSTRACT FROM AUTHOR]

This study presents an oversampling-based low-latency, high-resolution and low-cost timing synchronisation technique for digital receivers. Traditional timing synchronisation employs matched filter to estimate the signal coarse time of arrival. Here, latency increases through oversampling and resolution improves via higher bandwidth. The proposed method uses single bit quantisation to employ XNOR blocks instead of multiplier and accumulator blocks in the traditional method. This substantially decreases complexity incorporating less field-programmable gate array (FPGA) surface area. [ABSTRACT FROM AUTHOR]

According to the dS/CFT correspondence, correlators of fields generated during a primordial de Sitter phase are constrained by three-dimensional conformal invariance. Using the properties of radially quantized conformal field theories and the operator-state correspondence, we glean information on some points. The Higuchi bound on the masses of spin- s states in de Sitter is a direct consequence of reflection positivity in radially quantized CFT3 and the fact that scaling dimensions of operators are energies of states. The partial massless states appearing in de Sitter correspond from the boundary CFT3 perspective to boundary states with highest weight for the conformal group. Finally, we discuss the inflationary consistency relations and the role of asymptotic symmetries which transform asymptotic vacua to new physically inequivalent vacua by generating long perturbation modes. We show that on the CFT3 side, asymptotic symmetries have a nice quantum mechanics interpretation. For instance, acting with the asymptotic dilation symmetry corresponds to evolving states forward (or backward) in 'time' and the charge generating the asymptotic symmetry transformation is the Hamiltonian itself. [ABSTRACT FROM AUTHOR]

This paper focuses on a distributed optimization problem associated with a time-varying multi-agent network with quantized communication, where each agent has local access to its convex objective function, and cooperatively minimizes a sum of convex objective functions of the agents over the network. Based on subgradient methods, we propose a distributed algorithm to solve this problem under the additional constraint that agents can only communicate quantized information through the network. We consider two kinds of quantizers and analyze the quantization effects on the convergence of the algorithm. Furthermore, we provide explicit error bounds on the convergence rates that highlight the dependence on the quantization levels. Finally, some simulation results on a l1-regression problem are presented to demonstrate the performance of the algorithm. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A detailed understanding of the conductance quantization and resistive switching phenomena in redox-based memories is crucial for realizing atomic-scale memory devices and for finding the adequate design principles on which they can be based. Here, the emergence of quantized conductance states and their correlation with resistive switching characteristics in polymer-based atomic switches are investigated using combinations of current-voltage measurements and first-principles density functional theory (DFT) simulations. Various conductance states, including integer and half-integer multiples of a single atomic point contact and fractional conductance variations, are observed in an Ag/polyethylene oxide/Pt device under sweeping of bias voltage. Moreover, highly controllable and reproducible quantized conductance behaviors by tuning the voltage sweep rate and the sweep voltage range, suggesting well-controlled formation of the atomic point contact, are demonstrated. The device also exhibits longer retention times for higher conductance states. The DFT simulations reveal the transmission eigenstate of geometrically optimized atomic point contact structures and the impact of the atomic configurations and structural stability on the conductance state, which also explains their resistive switching behaviors. The well-defined, multiple quantized conductance states observed in these polymer-based atomic switches show promise for the development of new multilevel memory devices. [ABSTRACT FROM AUTHOR]

ABSTRACT The phase quantization effects of coded metasurface on agile scattering control are presented. Different phase resolutions are computed for a coded metasurface to realize two representative scattering fields, namely anomalous reflection and diffuse reflection. Detailed analysis of the results indicates that 2-bit coding is necessary to redirect the scattering beam to an arbitrarily focused direction and the derived beamwidth depends on the metasurface size and beam direction, while 1-bit coding is sufficient to redirect the energy to the entire space evenly. Simulations of a 1-bit coded metasurface are performed to validate the computations. Measurements of the metasurface are carried out to further verify the simulations and demonstrate the agile scattering performance. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:738-743, 2017 [ABSTRACT FROM AUTHOR]

Second-order generalised integrator or resonant integrator (RI) has wide range of applications. Forward and backward Euler's approximation based two integrator realisation of RI is an easily implementable frequency adaptive method. However, it suffers from resonant frequency deviation due to discretisation. The discretisation methods that lead to accurate realisation of RI require online calculation or lookup table of trigonometric functions to accommodate frequency variation. In this study, multi-rate computation-based implementation of two integrator-based RI has been proposed to minimise resonant frequency deviation. In this method, no additional logic elements are consumed to achieve accurate resonant frequency location. This along with down-sampling leads to lesser phase lag of RI. The effect of quantisation on resonant frequency deviation has been analysed for proper choice of calculation time. It is also shown that appropriate choice of down-sampling instants give a range of phase response characteristics around the nominal continuous time RI phase response. The accuracy of resonant frequency emulation has been experimentally verified by implementing a proportional-resonant controller as current controller. [ABSTRACT FROM AUTHOR]

We investigate transport through graphene nanoribbons in the presence of disorder scattering. We show that size quantization patterns are only present when [ABSTRACT FROM AUTHOR]

In this paper, we investigate the problems of stabilization of networked control systems with quantization and actuator saturation via delta operator approach. The definition of the domain of attraction for delta operator systems is introduced to analyze the stochastic stability of the closed-loop networked control systems. The quantizer is a uniform one with arbitrary quantization regions, and the packet dropout process is modeled as a Bernoulli process. On the basis of the zoom strategy and Lyapunov theory in delta domain, sufficient conditions are given for the closed-loop delta operator systems to be mean square stable, and the feedback controllers are designed to ensure the stability of networked control systems. A single link direct joint driven manipulator model is presented to show the effectiveness of the main results. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We present a theoretical study of lattice deformation and its influence on the electronic states and the optical transitions in Si and Ge nanocrystals covered by hydrogen. The lattice of Si and Ge nanocrystals has been optimized by Merck molecular force field method. The semiempirical tight-binding computer simulation has shown that the lattice optimization reduces effective energy band gap in silicon nanocrystals and increases it in germanium nanocrystals. This is similar to the effect of the hydrostatic compression of bulk Si and Ge. The sketch of the state density distribution in k-space is presented. It demonstrates the orbital-valley mixing, that appears due to space-quantization and lattice deformation influence. [ABSTRACT FROM AUTHOR]

The so-called Jackiw-Pi (JP) model for massive vector fields is a three-dimensional, gauge-invariant and parity-preserving model that was discussed in several contexts. In this paper we have discussed its quantum aspects through the introduction of Planck-scale objects, i.e., via noncommutativity and the well-known BV quantization. Namely, we have constructed the JP noncommutative space-time version, we have provided the BV quantization of the commutative JP model and we have discussed its features. The noncommutativity has introduced interesting new objects in JP's Planck-scale framework. [ABSTRACT FROM AUTHOR]

This paper is devoted to general optimal control problems (OCPs) associated with a family of nonlinear continuous-time switched systems in the presence of some specific control constraints. The stepwise (fixed-level type) control restrictions we consider constitute a common class of admissible controls in many real-world engineering systems. Moreover, these control restrictions can also be interpreted as a result of a quantization procedure appglied to the inputs of a conventional dynamic system. We study control systems with a priori given time-driven switching mechanism in the presence of a quadratic cost functional. Our aim is to develop a practically implementable control algorithm that makes it possible to calculate approximating solutions for the class of OCPs under consideration. The paper presents a newly elaborated linear quadratic-type optimal control scheme and also contains illustrative numerical examples. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations yield large amounts of trajectory data. For their durable storage and accessibility an efficient compression algorithm is paramount. State of the art domain-specific algorithms combine quantization, Huffman encoding and occasionally domain knowledge. We propose the high resolution trajectory compression scheme (HRTC) that relies on piecewise linear functions to approximate quantized trajectories. By splitting the error budget between quantization and approximation, our approach beats the current state of the art by several orders of magnitude given the same error tolerance. It allows storing samples at far less than one bit per sample. It is simple and fast enough to be integrated into the inner simulation loop, store every time step, and become the primary representation of trajectory data. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

This paper is concerned with the problem of H ∞ filtering for discrete-time Markov jump linear system with parametric uncertainties and quantized measurements, when the jumping mode information is not accessible. By converting the quantized errors into a sector-bounded nonlinearity, the parametric uncertainties and measurements quantization are dealt with in a unified framework. The mode-independent H ∞ filter is designed, and sufficient conditions are established via Lyapunov function approach, such that for all possible uncertain parameters and quantization errors, the resulting filtering error system is robustly stochastically stable and achieves a guaranteed H ∞ filtering error performance index. A numerical example is provided to demonstrate the feasibility and effectiveness of the proposed approach. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Proper range and precision analysis play an important role in the development of fixed-point algorithms for embedded system applications. Numerical linear algebra algorithms used to find singular value decomposition of symmetric matrices are suitable for signal and image-processing applications. These algorithms have not been attempted much in fixed-point arithmetic. The reason is wide dynamic range of data and vulnerability of the algorithms to round-off errors. For any real-time application, the range of the input matrix may change frequently. This poses difficulty for constant and variable fixed-point formats to decide on integer wordlengths during float-to-fixed conversion process because these formats involve determination of integer wordlengths before the compilation of the program. Thus, these formats may not guarantee to avoid overflow for all ranges of input matrices. To circumvent this problem, a novel dynamic fixed-point format has been proposed to compute integer wordlengths adaptively during runtime. Lanczos algorithm with partial orthogonalization, which is a tridiagonalization step in computation of singular value decomposition of symmetric matrices, has been taken up as a case study. The fixed-point Lanczos algorithm is tested for matrices with different dimensions and condition numbers along with image covariance matrix. The accuracy of fixed-point Lanczos algorithm in three different formats has been compared on the basis of signal-to-quantization-noise-ratio, number of accurate fractional bits, orthogonality and factorization errors. Results show that dynamic fixed-point format either outperforms or performs on par with constant and variable formats. Determination of fractional wordlengths requires minimization of hardware cost subject to accuracy constraint. In this context, we propose an analytical framework for deriving mean-square-error or quantization noise power among Lanczos vectors, which can serve as an accuracy constraint for wordlength optimization. Error is found to propagate through different arithmetic operations and finally accumulate in the last Lanczos vector. It is observed that variable and dynamic fixed-point formats produce vectors with lesser round-off error than constant format. All the three fixed-point formats of Lanczos algorithm have been synthesized on Virtex 7 field-programmable gate array using Vivado high-level synthesis design tool. A comparative study of resource usage and power consumption is carried out. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Motivated by the significance of optimizing network performance with limited resources in real applications, we investigate the problem of achieving fast and desired consensus in a complex network via pinning control a fraction of nodes in the network. An optimization problem is proposed to select p optimal pinned nodes to guarantee fastest consensus, which is relaxed to a Mixed-Integer Semi-Definite Program. In the single pinned node case ( i.e., p = 1), we find that the optimal pinned node is the node with highest min-max distance centrality within the nodes with highest closeness centrality in the network. In the multiple pinned nodes case ( i.e., p > 1), we find that betweenness centrality could be used as a suboptimal index to select pinned nodes. [ABSTRACT FROM AUTHOR]

In extreme excess modeling, one fits a generalized Pareto (GP) distribution to rainfall excesses above a properly selected threshold u. The latter is generally determined using various approaches, such as nonparametric methods that are intended to locate the changing point between extreme and nonextreme regions of the data, graphical methods where one studies the dependence of GP-related metrics on the threshold level u, and Goodness-of-Fit (GoF) metrics that, for a certain level of significance, locate the lowest threshold u that a GP distribution model is applicable. Here we review representative methods for GP threshold detection, discuss fundamental differences in their theoretical bases, and apply them to 1714 overcentennial daily rainfall records from the NOAA-NCDC database. We find that nonparametric methods are generally not reliable, while methods that are based on GP asymptotic properties lead to unrealistically high threshold and shape parameter estimates. The latter is justified by theoretical arguments, and it is especially the case in rainfall applications, where the shape parameter of the GP distribution is low; i.e., on the order of 0.1-0.2. Better performance is demonstrated by graphical methods and GoF metrics that rely on preasymptotic properties of the GP distribution. For daily rainfall, we find that GP threshold estimates range between 2 and 12 mm/d with a mean value of 6.5 mm/d, while the existence of quantization in the empirical records, as well as variations in their size, constitute the two most important factors that may significantly affect the accuracy of the obtained results. [ABSTRACT FROM AUTHOR]

The formation of quantized energy states in ultrathin layers of indium oxide (In2O3) grown via spin coating and thermally annealed at 200 °C in air is studied. Optical absorption measurements reveal a characteristic widening of the optical band gap with reducing In2O3 layer thickness from ≈43 to ≈3 nm in agreement with theoretical predictions for an infinite quantum well. Through sequential deposition of In2O3 and gallium oxide (Ga­2O3) layers, superlattice-like structures with controlled dimensionality and spatially varying conduction band characteristics are demonstrated. This simple method is then explored for the fabrication of functional double-barrier resonant tunneling diodes. Nanoscale current mapping analysis using conductive atomic force microscopy reveals that resonant tunneling is not uniform but localized in specific regions of the apparent device area. The latter observation is attributed to variation in the layer(s) thickness of the In2O3 quantum well and/or the Ga2O3 barrier layers. Despite the nonidealities, the tremendous potential of solution-processable oxide semiconductors for the development of quantum effect devices that have so far been demonstrated only via sophisticated growth techniques is demonstrated. [ABSTRACT FROM AUTHOR]

This paper deals with robust stability and stabilization of linear discrete-time systems subject to uncertainties and network constraints. In network control systems, the control loop is closed over a network, which induces additional dynamics to the original control loop such as delays, sampling, and quantization among many others. This paper focuses on networked induced delays due to unreliable network for which packet losses may occur. An equivalent periodic-like representation of the resulting system is proposed. This allows first to revisit existing results in this framework and second to take model uncertainties into account by analyzing the closed-loop model by means of a recent method based on robust control for discrete-time time-varying systems. Stability analysis and dynamic state-feedback stabilization are characterized via new conditions, whose conservatism is extensively discussed. Effectiveness of the proposed methodology is illustrated by numerical examples. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper deals with the fault detection (FD) problem for linear discrete time-varying (LDTV) systems subject to multiple intermittent observations and quantization errors. A set of independent identical distributed random variables are introduced as the indicators of the observation sequences to describe the multiple intermittent measurements. The measured observation is quantized by a logarithmic type quantizer. Our focus is to construct an observer-based fault detection filter (FDF) to recognize the fault in spite of multiple measurement packet dropouts and quantization inaccuracy. By defining generalized input-to-output operators, the FD problem is formulated into a two-objective optimization framework such that stochastic H ∞/ H ∞ or H−/ H ∞ performance index is maximized. Probability/indicators-dependent and probability-dependent analytical solutions are respectively derived by virtue of an adjoint operator based optimization approach for two cases. One is that the indicators are on-line known while the other one is that the indicators are not available at each time instant. An illustrative example is employed to demonstrate the effectiveness and applicability of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper, a new model is proposed to describe networked control systems (NCS) with delays and quantization errors. Firstly, the non-idealizations are unified in the classic robust control framework and the entire system is modeled as a discrete system closed via a block uncertainty. Then, the stability criteria are derived using small gain theorem, μ tool and integral quadratic constraint (IQC) method, respectively. Finally, a simulation and a numerical example are provided to demonstrate the effectiveness of the proposed methods. This work is supported by the Science Foundation of China University of Petroleum, Beijing (No.YJRC-2013-11) and National Natural Science Foundation (NNSF) of China under Grant 61374033. [ABSTRACT FROM AUTHOR]

We study Smoluchowski-Poisson equation in two space dimensions provided with Dirichlet boundary condition for the Poisson part. For this equation, several profiles of blowup solution have been noticed: blowup threshold on L1 norm of the initial value, finiteness of blowup points, formation of delta singularities called collapses, occurrence of type II blowup, exclusion of the boundary blowup point, and so forth. Here, we show the collapse mass quantization with possible residual terms. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The 4-dimensional space-time is extended to pseudo-complex coordinates. Proposing the standard quantization rules in this extended space, the ones for the 4-dimensional sub-space acquire, as one solution, the commutation relations with non-commuting coordinates. This demonstrates that the algebraic extension keeps the simple structure of Quantum Mechanics, while it also introduces an effective quite involved structure in the 4-dimensional sub-space. The first steps to pseudo-complex Quantum Mechanics in 1-dimension are outlined, awaiting still the interpretation of some new emerging structures. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The superconductor to normal metal phase transition induced by the in-plane magnetic field is studied in free-standing Pb(111) nanofilms. In the considered structures, the energy quantization induced by the confinement leads to the thickness-dependent oscillations of the critical field (the so-called 'shape resonances'). In this paper, we examine the influence of the orbital effect on the in-plane critical magnetic field in nanofilms. We demonstrate that the orbital term suppresses the critical field and reduces the amplitude of the thickness-dependent critical field oscillations. Moreover, due to the orbital effect, the slope [ABSTRACT FROM AUTHOR]

A novel observer-based fault accommodation technique for linear multi-input multi-output sampled-data systems affected by a general class of actuator faults in the presence of quantization errors is addressed in the paper. Only the output signal has been assumed to be available for direct measurement. A simulation study on a three-tank system supports theoretical developments. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Digital holography (DH) is a 3D imaging technique with a theoretical axial resolution of better than 1-2 nm However, practically, the axial resolution has been quoted to be in the range 10-20 nm. One possible reason is that the axial error is much larger so that the theoretical axial resolution cannot be achieved. The contributors to the axial errors of DH system need to be identified in order to reduce the errors. In this paper, the influence of space variant effect on the axial error is investigated by both simulation and experiment. The results show that space variant effect relates to the axial error. Position further away from optical axis suffers severer axial error. Asymmetrical displacement of object causes asymmetrical axial error. Therefore, objects are suggested to be placed on the optical axis and symmetrically for a better axial accuracy. [ABSTRACT FROM AUTHOR]

In this article, we develop a formalism to obtain the energy levels of the electron in a central force potential confined in a spherical quantum dot with radius rC by the proper quantization rule and the Wentzel-Kramers-Brillouin approximation. It is shown that the numerical results are in good agreement with exact solutions. To illustrate this method, we consider the linear harmonic oscillator and Coulomb potential confined within an impenetrable sphere of radius rC in three dimensions. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We discuss how we formulate time evolution of physical quantities in the framework of the Rigged quantum electrodynamics (QED). The Rigged QED is a theory which has been proposed to treat dynamics of electrons, photons, and atomic nuclei in atomic and molecular systems in a quantum field theoretic way. To solve the dynamics in the Rigged QED, we need different techniques from those developed for the conventional QED. As a first step toward this issue, we propose a procedure to expand the Dirac field operator, which represents electrons, by the electron annihilation/creation operators and solutions of the Dirac equation for electrons in nuclear potential. Similarly, the Schrödinger field operators, which represent atomic nuclei, are expanded by nucleus annihilation/creation operators. Then, we derive time evolution equations for these annihilation and creation operators and discuss how time evolution of the operators for physical quantities can be calculated. In the end, we propose a method to approximate the evolution equations of the operators by the evolution equations for the density matrices of electrons and atomic nuclei. Under this approximation, we carry out numerical simulation of the time evolution of electron charge density of a hydrogen atom. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We present extensive calculations on the quantization behaviors of first-order nonadiabatic couplings (NAC) in polyatomic systems, using the method based on time-dependent density functional theory (TDDFT). Along circular contours around Jahn-Teller conical intersections at various symmetries, such as D4 h and D6 h, the angular NAC are found to show apparent dependence on the contour angle, no matter how close the conical intersections are approached. This is in contrast to that the angular NAC in triatomic Jahn-Teller systems (D3 h) converge to the quantized value of 1/2. The oscillatory feature of our calculated curves qualitatively resembles the analytic result of angular NAC around elliptic conical intersections in the small-displacement limit. Furthermore, by performing the integral along the whole contour, the quantization rule on the integral of the angular NAC holds for all cases, which gives the geometric phase with a value of π. On the other hand, the angular NAC in the immediate vicinity of Renner-Teller intersections are shown to be always 1. This observation can be understood from the fact that the molecular symmetry property of the Renner-Teller intersections is always determined by the linear atomic chain. Further analysis of our results on Renner-Teller systems shows that although the quantization behavior of angular NAC can determine all NAC vectors on each atom for the triatomic systems, it cannot for the systems with more than three atoms. The NAC vectors of the latter systems are found to show both common and distinct features with respect to the atomic number and species by our TDDFT calculations. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We investigate whether specific properties of molecular dynamics trajectory files can be exploited to achieve effective file compression. We explore two classes of lossy, quantized compression scheme: 'interframe' predictors, which exploit temporal coherence between successive frames in a simulation, and more complex 'intraframe' schemes, which compress each frame independently. Our interframe predictors are fast, memory-efficient and well suited to on-the-fly compression of massive simulation data sets, and significantly outperform the benchmark BZip2 application. Our schemes are configurable: atomic positional accuracy can be sacrificed to achieve greater compression. For high fidelity compression, our linear interframe predictor gives the best results at very little computational cost: at moderate levels of approximation (12-bit quantization, maximum error ≈ 10−2 Å), we can compress a 1-2 fs trajectory file to 5-8% of its original size. For 200 fs time steps-typically used in fine grained water diffusion experiments-we can compress files to ∼25% of their input size, still substantially better than BZip2. While compression performance degrades with high levels of quantization, the simulation error is typically much greater than the associated approximation error in such cases. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

ABSTRACT Precorrelation filtering, sampling, and quantization are three fundamental functions for GNSS receivers. Analytical model and numerical simulation methods have been developed to evaluate the implementation losses due to different combinations of these parameters, first in the context of white noise and later non-white interference. However, the performance metric was loss of effective carrier-to-noise density ratio (C/N0). This is indirect in predicting the performance degradation of a delay-lock loop (DLL). This paper proposes an analytical model to predict the DLL performance with loss of root-mean-squared (RMS) tracking accuracy in meters. In the current project, a wideband Compass receiver capable of processing modern GNSS signals is required to form the core of the GNSS Vulnerabilities Assessment and Validation Platform (VAVE). The method proposed was used to determine the optimal combination of precorrelation bandwidth, sampling frequency, and quantization to guide the design of VAVE receiver hardware. Here optimality means highest possible performance with minimized implementation cost. Copyright © 2012 Institute of Navigation [ABSTRACT FROM AUTHOR]

We consider some Coulomb systems with several infinitely massive centers of charge Z and one or two electrons: ( Z, e), (2 Z, e), (3 Z, e), (4 Z, e), (2 Z, e, e), and (3 Z, e, e). It is shown that the physical, integer charges Z = 1,2,... do not play a distinguished role for the total energy and for the equilibrium configuration of a system, giving no indication of a charge quantization. By definition, a critical charge Zcr for a given Coulomb system ( nZ, e) or ( nZ, e, e) is a charge which separates the domain of the existence of bound states from the domain of unbound states (the domain of stability), the continuum (the domain of instability). For all the above-mentioned systems critical charges Zcr as well as equilibrium geometrical configurations are found. Furthermore, an indication to a branch point singularity at Z = Zcr with exponent 3/2 was obtained. It is demonstrated that in the domain of the existence the optimal geometrical configuration for both ( nZ, e) at n = 2,3,4 and ( nZ, e, e) at n = 2,3 corresponds to the Platonic body. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 [ABSTRACT FROM AUTHOR]

In this paper, we consider the state estimation problem for linear discrete time-varying systems subject to limited communication capacity which includes measurement quantization, random transmission delay and data-packet dropouts. Based on transforming the three communication limitations into the system with norm-bounded uncertainties and stochastic matrices, we design a robust filter such that, for all the communication limitations, the error state of the filtering process is mean square bounded. An upper bound on the variance of the state estimation error is first found, and then, a robust filter is derived by minimizing the prescribed upper bound in the sense of the matrix norm. It is shown that the desired filter can be obtained in terms of the solutions to two Riccati-like difference equations which also provide a recursive algorithm suitable for online computation. A simulation example is presented to demonstrate the effectiveness and applicability of the proposed algorithm. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [ABSTRACT FROM AUTHOR]

We investigate the ability of the multiplicative random cascade model to accurately simulate temporal precipitation. Specifically, we explore the effect of the dependence structure in cascade weights due to clustering and within-storm variability on the temporal correlation in simulated precipitation, and we compare the results with data at 69 stations with 10 min precipitation records in Switzerland. Correlation is quantified with the oscillation coefficient, which is a measure of patterns of fluctuations in data. Simulation results show that the assumption of temporal independence in cascade weights is generally not supported by observations of both rainfall and snowfall, which show generally higher correlation (lower fluctuations) at the hourly time resolution. Seasonal signatures are also apparent, with higher correlation in the cold season with dominant stratiform precipitation than in the warm season with convective precipitation. Measurement artifacts caused by the tipping bucket mechanism at high resolutions (10 min) are shown to play a significant role in the estimation of the correlation structure in cascade weights because of the quantization of precipitation intensity by the tip volume and sampling time resolution of the gauge. These effects are smoothed out at resolutions above 1 h when the oscillation coefficients become independent of resolution. Such measurement artifacts may have an important effect on the estimated scaling and correlation behavior in precipitation at high temporal resolutions. [ABSTRACT FROM AUTHOR]

We elaborate on the construction of de Sitter solutions from IIA orientifolds of SU(3)-structure manifolds that solve the 10-dimensional equations of motion at tree-level in the approximation of smeared sources. First we classify geometries that are orbifolds of a group manifold covering space which, upon the proper inclusion of O6 planes, can be described within the framework of 𝒩 = 1 supergravity in 4D. Then we scan systematically for de Sitter solutions, obtained as critical points of an effective 4D potential. Apart from finding many new solutions we emphasize the challenges in constructing explicit classical de Sitter vacua, which have sofar not been met. These challenges are interesting avenues for further research and include finding solutions that are perturbatively stable, satisfy charge and flux quantization, and have genuine localized (versus smeared) orientifold sources. This paper intends to be self-contained and pedagogical, and thus can serve as a guide to the necessary technical tools required for this line of research. In an appendix we explain how to study flux and charge quantization in the presence of a non-trivial H-field using twisted homology. [ABSTRACT FROM AUTHOR]

In this talk we discuss implications of the concept of the minimal length, the Planck length, for black hole physics, and argue, that it naturally leads to quantization of black hole area in Planck units. [ABSTRACT FROM AUTHOR]