Geometric Character Research Articles

Relaxation dynamics near the sol–gel transition: From cluster approach to mode-coupling theory

A long standing problem in glassy dynamics is the geometrical interpretation of clusters and the role they play in the observed scaling laws. In this context, the mode-coupling theory (MCT) of type-A transition and the sol–gel transition are both characterized by a structural arrest to a disordered state in which the long-time limit of the correlator continuously approaches zero at the transition point. In this paper, we describe a cluster approach to the sol-gel transition and explore its predictions, including universal scaling laws and a new stretched relaxation regime close to criticality. We show that while MCT consistently describes gelation at mean-field level, the percolation approach elucidates the geometrical character underlying MCT scaling laws.

Research Progress on Wind-Resistant and Seismic Performance of Glass Curtain Wall Supported by Plane Cable Net

Glass curtain wall supported by plane cable net (PCNCW) is very popular in civil engineering for its advantages of beautiful appearance and good permeability etc. Because plane cable net (PCN) has the obvious geometrical nonlinear character and its dynamic response is affected by the main structure it attached to, it has to be considered particularly in wind-resistant and seismic design. In recent years, many research results have been achieved on wind-resistant and seismic performance of PCNCW, including the study on how to calculate the equivalent static wind and seismic load, how the factors influence the wind-resistant force behavior, discussion on seismic fortification criterion, and how it is influenced by the main structure under wind and seismic load. These results are overviewed and the problems needed to be further studied in the future is prospected.

Anodic aluminum oxide nanograting for back light trapping in thin c-Si solar cells

Enhanced absorption of near infrared light in silicon solar cells is important for achieving high conversion efficiencies while reducing the solar cell׳s thickness. In our work, a light trapping structure combined with anodic aluminum oxide (AAO) nanograting and Ag thin layer was proposed. The finite difference time domain (FDTD) method was used to study the relationship between AAO׳s geometrical parameters and light absorption character of thin Si solar cells. Simulation results show that the optimum AAO parameter is 0.75 for the duty circle, 380nm for period and 90nm for thickness. Absorption spectrum shows that, AAO in optimum structure can highly increase light absorption for Si solar cell in wavelength from 500 to 1100nm. Parameter tolerance analyzing of AAO shows that, choosing AAO as a back light trapping structure allows a tolerance more than ±10% for period and about −5% to 20% for thickness.

The Flexible Control System Development of the Sawing and Milling Machining Center for PVC Door and Window Profile

In the paper, with the secondary development of FANUC-0MD system, the flexible control system which meets the requirements of the sawing and milling machining center for PVC door and window profile is realized. Based on researching the structure, the function, the process of the technologies and the control requirements of the machining center, the CNC system has implemented, including the machine tool origin and work piece coordinate origin establishment and auxiliary control system M code development. In this flexible control system, through studying the geometric character, the technical character and the mutual relation between them, various windows shape on the structure and the machining figuration is possessed of. We gain the feature subclasses aggregate of the machining technology of windows shape. Consequently, CAM system is achieved.

Geometry in the Entanglement Dynamics of the Double Jaynes–Cummings Model

We report on the geometric character of the entanglement dynamics of two pairs of qubits evolving according to the double Jaynes–Cummings model. We show that the entanglement dynamics for the initial states | ψ 0〉 = cos α | 10〉 + sin α | 01〉 and | ϕ 0〉 = cos α | 11〉 + sin α | 00〉 cover three-dimensional surfaces in the diagram C ij × C ik × C il , where C mn stands for the concurrence between qubits m and n, varying 0 ≤ α ≤ π / 2. In the first case, projections of the surfaces on a diagram C ij × C kl are conics. In the second case, curves can be more complex. We relate those conics with a measurable quantity, the predictability. We also derive inequalities limiting the sum of the squares of the concurrence of every bipartition and show that sudden death of entanglement is intimately connected to the size of the average radius of a hypersphere.

Bifurcation in calculus of variations with constraints

We describe a variational problem on a domain of a plane under a constraint of geometrical character. We provide sufficient and necessary conditions for the existence of bifurcation points. The problem in 2 coordinate form, corresponds to a quasilinear elliptic boundary value problem. The problem provides a physical model for several applications referring to continuum media and membranes.

Driven geometric phase gates with trapped ions

We describe a hybrid laser–microwave scheme to implement two-qubit geometric phase gates in crystals of trapped ions. The proposed gates can attain errors below the fault-tolerance threshold in the presence of thermal, dephasing, laser-phase and microwave-intensity noise. Moreover, our proposal is technically less demanding than previous schemes, since it does not require a laser arrangement with interferometric stability. The laser beams are tuned close to a single vibrational sideband to entangle the qubits, while strong microwave drivings provide the geometric character to the gate, and thus protect the qubits from these different sources of noise. A thorough analytic and numerical study of the performance of these gates in realistic noisy regimes is presented.

Nonsingular Promises from Born-Infeld Gravity

Born-Infeld determinantal gravity formulated in Weitzenböck spacetime is discussed in the context of Friedmann-Robertson-Walker (FRW) cosmologies. It is shown how the standard model big bang singularity is absent in certain spatially flat FRW spacetimes, where the high energy regime is characterized by a de Sitter inflationary stage of geometrical character, i.e., without the presence of the inflaton field. This taming of the initial singularity is also achieved for some spatially curved FRW manifolds where the singularity is replaced by a de Sitter stage or a big bounce of the scale factor depending on certain combinations of free parameters appearing in the action. Unlike other Born-Infeld-like theories in vogue, the one here presented is also capable of deforming vacuum general relativistic solutions.

Tread wear and footprint geometrical characters of truck bus radial tires

Wear and mileage performance are the foremost performances for truck bus radial (TBR) tires. There are a lot of researches about the tire wear performance as well as the contact patch phenomenon by using finite element analysis (FEA) method or testing. But there is little published data on the correlations between the footprint geometry and the tread wear performance of tires. In this paper, an experiment on tire-ground performance of TBR tires is carried out by using Tekscan. The real-time changes of contact-area pressure distribution that occurred during the process of continuous load and unload are recorded. Three types of tires that act differently in behavior under normal usage are analyzed. A new method of researching in tire tread wear, which focuses on the geometrical characters of the footprint, is put forward. The experimental results of the three tires are described by using footprint geometrical characters. On the basis of studying the changing laws of footprint geometrical characters during the loading process and considering consumer survey and factory feedback information, the correlations between the geometrical character of footprints and tread destruction form are built. The analyzed results show that a greater contact area coefficient and a steady coefficient of contact result in a better wear performance for TBR tires. The footprint-shape coefficient changing laws in the process of loading are found to have a very good coincidence with the tread wear of the three types of tires. Tires with a smaller footprint-shape coefficient are likely to have an average tread wear while avoiding the shoulder wear first. The proposed research provides a new solution to predict tire-ground performance at the point of footprint and several useful references for improving tire design.

The Types: A Persistent Structuralist Challenge to Darwinian Pan-Selectionism

Here I first review the structuralist or typological world view of pre-1859 biology, and the concept that the basic forms of the natural world--the Types--are immanent in nature, and determined by a set of special natural biological laws, the so called ‘laws of form’. I show that this conception was not based, as Darwinists often claim, on a priori philosophical belief in Platonic concepts, but rather upon the empirical finding that a vast amount of biological complexity, including the deep homologies which define the taxa of the natural system, appears to be of an abstract, non-adaptive nature that is sometimes of a strikingly numerical and geometric character. In addition, these Types exhibit an extraordinary robustness and stability, having in many instances remained invariant in diverse lineages for hundreds of millions of years. Second, I show that neither Darwinism nor any subsequent functionalist theory has ever provided a convincing adaptive or functionalist explanation for the Types or deep homologies. Third, I discuss how recent advances have provided new support for the structuralist notion that the basic forms of life are immanent in nature. These include the discovery of the cosmic fine-tuning of the laws of nature for life as it exists on earth, and advances in areas of molecular and cellular biology, where it is apparent that a considerable amount of biological complexity is clearly determined by the self-organizing properties of particular categories of matter, rather than being specified in detail in a genetic blueprint as functionalism demands.

Geometric Morphometric Character Suites as Phylogenetic Data: Extracting Phylogenetic Signal from Gastropod Shells

Despite being the objects of numerous macroevolutionary studies, many of the best represented constituents of the fossil record-including diverse examples such as foraminifera, brachiopods, and mollusks-have mineralized skeletons with limited discrete characteristics, making morphological phylogenies difficult to construct. In contrast to their paucity of phylogenetic characters, the mineralized structures (tests and shells) of these fossil groups frequently have distinctive shapes that have long proved useful for their classification. The recent introduction of methodologies for including continuous data directly in a phylogenetic analysis has increased the number of available characters, making it possible to produce phylogenies based, in whole or part, on continuous character data collected from such taxa. Geometric morphometric methods provide tools for accurately characterizing shape variation and can produce quantitative data that can therefore now be included in a phylogenetic matrix in a nonarbitrary manner. Here, the marine gastropod genus Conus is used to evaluate the ability of continuous characters-generated from a geometric morphometric analysis of shell shape-to contribute to a total evidence phylogenetic hypothesis constructed using molecular and morphological data. Furthermore, the ability of continuous characters derived from geometric morphometric analyses to place fossil taxa with limited discrete characters into a phylogeny with their extant relatives was tested by simulating the inclusion of fossil taxa. This was done by removing the molecular partition of individual extant species to produce a "cladistic pseudofossil" with only the geometric morphometric derived characters coded. The phylogenetic position of each cladistic pseudofossil taxon was then compared with its placement in the total evidence tree and a symmetric resampling tree to evaluate the degree to which morphometric characters alone can correctly place simulated fossil species. In 33-45% of the test cases (depending upon the approach used for measuring success), it was possible to place the pseudofossil taxon into the correct regions of the phylogeny using only the morphometric characters. This suggests that the incorporation of extinct Conus taxa into phylogenetic hypotheses will be possible, permitting a wide range of macroevolutionary questions to be addressed within this genus. This methodology also has potential to contribute to phylogenetic reconstructions for other major components of the fossil record that lack numerous discrete characters.

Handwritten Character Recognition Using Competitive Neural Trees

Neural network classifier methods and decision trees are widely used in various pattern recognition research areas. Among them, handwritten character recognition still faces some issues in all languages. Myanmar handwritten character recognition based on Competitive Neural Trees (CNeT) is proposed in this paper. CNeT performs hierarchical classification and apply competitive unsupervised learning at node label. The goals of Myanmar handwritten character recognition are to obtain better recognition accuracy rate and robust in geometric character shapes of different writing styles. Three main steps such as preprocessing, shape feature descriptors extraction and recognition are implemented in our experiment. Shape feature descriptors are extracted from preprocessed images which are used in Competitive Neural Trees (CNeT) for recognition. This paper discusses a global search method for the CNeT, which is utilized for training.

Estimation of Engine Torque and Cylinder Pressure Index Based on Crankshaft Rotation Measurement

The recent regulations for engine emissions require precise temperature control. Because high response temperature measurement is difficult, engine torque, which is closely correlated with the temperature, must be estimated. We propose a method for estimating engine torque from the crankshaft rotation speed. This method consists of four steps, (1) the measured engine speed ω is analyzed and divided into frequency components, (2) each component is multiplied by the gain, which is proportional to the frequency, (3) the phase of each component is shifted by 2π/4, (4) the combustion torque is estimated by synthesizing each component. These steps are summarized into one filter. The output of the filter is compensated for by the geometrical character of the engine link mechanism. The method was evaluated through experimentation. In the steady and transient states and under the condition that the engine speed was not greater than 1000 rpm, the estimated torque accurately follows the reference torque. However, when the engine speed increases to 2000 rpm, the pulsation in the estimated torque becomes noticeable. Based on the estimated torque, IMEP was estimated within an accuracy of 3.4% when the engine speed was not greater than 1000 rpm. When the valve timing changed, the estimated IMEP followed the change in reference IMEP.

InSpace3D: A Middleware for Built Environment Data Access and Analytics

Standardisation, archiving, and digital access of spatial data pertaining to built-up environments is an area acquiring increasing attention amongst several interest groups: policy makers, designers and planners, civil engineers, infrastructure management and public service personnel, building users. Initiatives such as the Building Information Model (BIM), Industry Founda- tion Classes (IFC), and CityGML are creating the information-theoretic backbone that guides the crucial aspects of quality, exchange, and interoperability of spatial data at the environmental and urban scale. However, due to the inherent scale, com- plexity, and detailed geometric character of building information data, extracting useful semantic and qualitative knowledge for accomplishing high-level analytical tasks is still an extremely complex and error prone process involving data intensive computing. We propose a uniform spatial data access middleware that can provide a combination of high-level, multi-modal, semantic, and quantitative-qualitative spatial data access and analytical capability. We present the core computational capabil- ities for the proposed middleware and present an overview of the high-level spatial model and its compliance with the industry standard IFC. A key theoretical contribution is a framework for investigating the computational complexity of deriving spatial artefacts within the context of building informatics. Additionally, we empirically investigate the feasibility and practicality of the derivation of spatial artefacts by conducting experiments on seven industry-scale IFC models. The experiment results show that, despite having non-linear polynomial increase with respect to time, deriving spatial artefacts is practical with large designs.

Sharp Increase in the (Hyper)polarizabilities of Quinoid-Type Isonaphtothiophene (INT) Oligomers: A Quantum Chemical Insight

The conductivity and nonlinear optical properties of isonaphtothiophene (INT)(n) are investigated by quantum chemical techniques. The conducting properties of (INT)(n) are examined by density of states (DOS) and local DOS analyses. As the chain length n increases, the geometrical conformations of (INT)(n) changed, and the energy gap suddenly decreases. The energy potentials and rotation effect are explored to determine the most preferred stable structures. The geometrical and intrinsic charge character are analyzed by UV/vis/NIR spectra and confirmed by frontier orbital analysis. Interestingly, the (hyper)polarizabilities of (INT)(n) oligomers increase sharply as the chain length increased. Additionally, the importance of the side β double bonds effect on the structural transformation is detected by a new quantum chemical technique resulting in a potential polymer conductor that can be controlled by modifying its side chains.

Geometric phases generated by the non-trivial spatial topology of static vector fields linearly coupled to a neutral spin-endowed particle: application to 171Yb atoms trapped in a 2D optical lattice

We have constructed the geometric phases emerging from the non-trivial topology of a space-dependent magnetic field B(r), interacting with the spin magnetic moment of a neutral particle. Our basic tool, adapted from a previous work on Berry’s phases, is the space-dependent unitary transformation , which leads to the identity, , at each point r. In the ‘rotated’ Hamiltonian , is replaced by the non-Abelian covariant derivative where can be written as A1(r)Sx + A2(r)Sy + A3(r)Sz. The Abelian differentials Ak(r)·dr are given in terms of the Euler angles defining the orientation of B(r). The non-Abelian field transforms as a Yang–Mills field; however, its vanishing ‘curvature’ reveals its purely geometric character. We have defined a perturbation scheme based upon the assumption that in the longitudinal field A3(r) dominates the transverse field A1, 2(r) contributions, evaluated to second order. The geometry embedded in both the vector field A3(r) and the geometric magnetic field is described by their associated Aharonov–Bohm phase. As an illustration we study the physics of cold 171Yb atoms dressed by overlaying two circularly polarized stationary waves with orthogonal directions, which form a 2D square optical lattice. The frequency is tuned midway between the two hyperfine levels of the (6s6p)3P1 states to protect the optical B(r) field generated by the lattice from the dressed atom instability. The geometric field B3(r) is computed analytically in terms of the Euler angles. The magnitude of the second-order corrections due to the transverse fields can be reduced to the per cent level by a choice of light intensity that keeps the dressed atom loss rate ⩽5 s−1. A second optical lattice can be designed to confine the atoms inside 2D domains where . We extend our analysis to the case of a triangular lattice.

Dynamics and Synchronization of Dual Phase

This article presents dynamics of dual phase, which is connected with dual character of dions - hypothetical particles possessing both electrical and magnetic charges. For description of dual phase the set of equations is received from condition that Maxwell equations conserve their electrical character under dual transformations, what corresponds to effec- tive electrical charge of dion. The mechanism of dual phase synchronization in different parts of space is revealed. It is shown, that solutions of Maxwell equations for spherical waves with zero orbital moment momentum correspond to monopole ra- diation of dion. Goldstone character of dual phase so as its geometrical character is shown. This article supplements previous investigations of G. Rainich(1) and J. Wheeler and C. Misner(2, 3). Results of this article can explain many-years failures in searching magnetic charges (monopoles).

Geometric character of domain and the Harnack inequality of solution of a singular parabolic equation

Abstract The geometric character of domains of solutions of a singular parabolic equation with the Neumann boundary condition are discussed in this work. We prove a gradient estimate and a Harnack type inequality and then, show that the domains of the solutions are exactly columns in the space-time. Specially, the altitudes of the columns are calculated accurately.

Rapid directional changes associated with a 6.5 kyr-long Blake geomagnetic excursion at the Blake–Bahama Outer Ridge

Geomagnetic excursions are recognized as intrinsic features of the Earth's magnetic field. High-resolution records of field behaviour, captured in marine sedimentary cores, present an opportunity to determine the temporal and geometric character of the field during geomagnetic excursions and provide constraints on the mechanisms producing field variability. We present here the highest resolution record yet published of the Blake geomagnetic excursion (∼125ka) measured in three cores from Ocean Drilling Program (ODP) Site 1062 on the Blake–Bahama Outer Ridge. The Blake excursion has a controversial structure and timing but these cores have a sufficiently high sedimentation rate (∼10cmka−1) to allow detailed reconstruction of the field behaviour at this site during the excursion. Palaeomagnetic measurements of the cores reveal rapid transitions (<500yr) between the contemporary stable normal polarity and a completely reversed state of long duration which spans a stratigraphic interval of 0.7m. We determine the duration of the reversed state during the Blake excursion using oxygen isotope stratigraphy, combined with 230Th excess measurements to assess variations in the sedimentation rates through the sections of interest. This provides an age and duration for the Blake excursion with greater accuracy and with constrained uncertainty. We date the directional excursion as falling between 129 and 122ka with a duration for the deviation of 6.5±1.3kyr. The long duration of this interval and the fully reversed field suggest the existence of a pseudo-stable, reversed dipole field component during the excursion and challenge the idea that excursions are always of short duration.

Spectral properties of oscillatory and non-oscillatory α2-dynamos

The eigenvalues and eigenfunctions of a linear α2-dynamo have been computed for different spatial distributions of an isotropic α-effect. Oscillatory solutions are obtained when α exhibits a sign change in the radial direction. The time-dependent solutions arise at the so-called exceptional points where two stationary modes merge and continue as an oscillatory eigenfunction with conjugate complex eigenvalues. The close proximity of oscillatory and non-oscillatory solutions may serve as the basic ingredient for reversal models that describe abrupt polarity switches of a dipole induced by noise. Whereas the presence of an inner core with different magnetic diffusivity has remarkable little impact on the character of the dominating dynamo eigenmodes, the introduction of equatorial symmetry breaking considerably changes the geometric character of the solutions. Around the dynamo threshold, the leading modes correspond to hemispherical dynamos even when the symmetry breaking is small. This behavior can be explained by an approximate dipole-quadrupole degeneration for the unperturbed problem. More complicated scenarios may occur in the case of more realistic anisotropies of α- and β-effect or through nonlinearities caused by the back-reaction of the magnetic field (magnetic quenching).