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Does defensive posture increase mimetic fidelity of caterpillars with eyespots to their putative snake models？

Current Zoology 2014年第1期60卷 76-89页

作者： thomas John HOSSIE thomas N. SHERRATT Ottawa-Carleton Institute of Biology Carleton University 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada Department of Biology Carleton University 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada

Organisms often evolve behaviours that increase or reinforce the protection from predators afforded by their morpho- logical defences. For example, mimetic animals may adopt postures or locomotory behaviours that emulate a characteristic fea- ture of their model to increase predator deception. Caterpillars with eyespots are thought to mimic snakes, and when threatened many of these caterpillars adopt a posture that appears to enhance this resemblance. Herein we evaluate the quantitative strength of evidence of behavioural mimicry in the caterpillars of 14 species by comparing how closely a series of putative snake-mimicking caterpillars resemble snakes while at rest and when threatened. Specifically, we quantified the head morphology and eye position of a range of snake species, as well as the shape of the apparent head （i.e. anterior body segments） and position of eyespots in caterpillars resting or in their defensive posture. This allowed us to objectively examine evidence for an increased resemblance to either snakes generally, or to Viperidae snakes specifically, upon adopting the defensive posture. Widening the anterior body segments during the defensive posture typically made caterpillars appear more viper-like as opposed to more snake-like in general. Enhanced resemblance to vipers upon mounting the defensive posture was apparent only from the dorsal view. Laterally, caterpillars more closely resembled snakes in the resting posture and shifting to the defensive posture instead reduced mimetic fidelity, Overall we found evidence for behavioural mimicry in all 14 species examined. We highlight that objectively quantifying mimetic fidelity can help identify key features involved in deception .

关键词： Behaviour Geometr!c morphometrics Protective colouration Mimicry Morphology Vipers

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Nanoscale chemical segregation to twin interfaces in τ-MnAl-C and resulting effects on the magnetic properties

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Journal of Materials Science & Technology 2023年第3期134卷 22-32页

作者： Panpan Zhao Markus Gusenbauer Harald Oezelt Daniel Wolf thomas Gemming thomas Schrefl Kornelius Nielsch thomas George Woodcock Leibniz IFW Dresden Helmholtzstr.20Dresden 01069Germany TU Dresden Institute of Materials ScienceDresden 01062Germany Department for Integrated Sensor Systems Danube University KremsKrems an der Donau 3500Austria

In this study,aberration-corrected scanning transmission electron microscopy coupled with electron energy-loss spectroscopy(STEM-EELS)was used to investigate the atomistic structure and chemical com-position of true twin and order twin boundaries in ferromagneticτ-*** twins and order twins were distinguished based on the diffraction patterns using *** elemental segregation was observed at the coherent true twin boundary but some Mn enrichment within a region of about 1.5-2 nm was found at the incoherent true twin boundary.A transition region with Mn enrichment about 4-6 nm wide was found at the order twin boundary.A carbon cluster with a size of around 5 nm was also found at the twin *** simulations were conducted to study the effect of this chemical seg-regation at twin interfaces on the magnetic *** results showed that the coercivity tends to increase with increasing structural and chemical disorder at the interface.

关键词： τ-MnAl-C Twin boundaries Elemental segregation STEM-EELS Micromagnetic simulations

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RADIATION BOUNDARY CONDITIONS FOR MAXWELL'S EQUATIONS:A REVIEW OF ACCURATE TIME-DOMAIN FORMULATIONS

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Journal of Computational Mathematics 2007年第3期25卷 305-336页

作者： thomas Hagstrom Stephen Lau Department of Mathematics and Statistics University of New MexicoAlbuquerqueNM 87131USA Division of Applied Mathematics Brown University182 George StreetProvidenceRI 02912USA

We review time-domain formulations of radiation boundary conditions for Maxwell＇s equations, focusing on methods which can deliver arbitrary accuracy at acceptable compu-tational cost. Examples include fast evaluations of nonlocal conditions on symmetric and general boundaries, methods based on identifying and evaluating equivalent sources, and local approximations such as the perfectly matched layer and sequences of local boundary conditions. Complexity estimates are derived to assess work and storage requirements as a function of wavelength and simulation time.

关键词： Maxwell's equations Radiation boundary conditions Fast algorithms Kirchoffformulas Perfectly matched layers.

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Loss of energy dissipation capacity from the deadzone in linear and nonlinear viscous damping devices

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Earthquake Engineering and Engineering Vibration 2007年第1期6卷 11-20页

作者： Mai Tong thomas Liebner Multidisciplinary Center for Earthquake Engineering Research State University of New York at Buffalo USA Department of Mechanical Engineering Pennsylvania State University

In a viscous damping device under cyclic loading, after the piston reaches a peak stroke, the reserve movement that follows may sometimes experience a short period of delayed or significantly reduced device force output. A similar delay or reduced device force output may also occur at the damper＇s initial stroke as it moves away from its neutral position. This phenomenon is referred to as the effect of ＂deadzone＂. The deadzone can cause a loss of energy dissipation capacity and less efficient vibration control. It is prominent in small amplitude vibrations. Although there are many potential causes of deadzone such as environmental factors, construction, material aging, and manufacture quality, in this paper, its general effect in linear and nonlinear viscous damping devices is analyzed. Based on classical dynamics and damping theory, a simple model is developed to capture the effect ofdeadzone in terms of the loss of energy dissipation capacity. The model provides several methods to estimate the loss of energy dissipation within the deadzone in linear and sublinear viscous fluid dampers. An empirical equation of loss of energy dissipation capacity versus deadzone size is formulated, and the equivalent reduction of effective damping in SDOF systems has been obtained. A laboratory experimental evaluation is carried out to verify the effect of deadzone and its numerical approximation. Based on the analysis, a modification is suggested to the corresponding formulas in FEMA 3 5 6 for calculation of equivalent damping if a deadzone is to be considered.

关键词： viscous damping device stroke deadzone sublinear viscous fluid dampers

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WHO WON THE 2008 OLYMPICS?A MULTICRITERIA DECISION OF MEASURING INTANGIBLES

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Journal of Systems Science and Systems Engineering 2008年第4期17卷 473-486页

作者： thomas L.SAATY University of Pittsburgh Pittsburgh PA 15260USA

It often happens that at the end of Olympics games the medals won by more than one country are many and close in total number as in the 2008 games where China won 100 medals with many gold ones and the United States won 110 medals but with a lesser number of gold medals. The question is： Although it is often done arbitrarily, is there a way to quantify the values of gold, silver and bronze medals legitimately to resolve this concern？ This short exposition shows that there is by using the author＇s theory for the measurement of intangibles, the Analytic Hierarchy Process.

关键词： Olympics medals China US measurement of intangibles points per GDP points per population

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Effect of particle size distribution on particle based composite anode models

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Acta Mechanica Sinica 2013年第3期29卷 357-369页

作者： Vaughan L.thomas Baltimore USA

Particle based models of composite anodes are useful tools for exploring the behavior of SOFC systems. As part of our efforts to develop models for understanding fuel cells, we have been building models of Ni-YSZ composite anodes using experimentally measured particle size distributions. The objectives of this study were to characterize the percolation threshold and conductivity of these models in comparison to simpler mono dispersed and biphasic particle size distributions from the literature. We found that the average values for the onset of percolation and the measured conductivity of the models with experimentally measured particle size distributions are similar to those for the simple distributions and the experimentally measured distributions. For all of the configurations evaluated, the onset of percolation in the Nickel phase occurred at a solid fraction of Nickel between 20% and 25%. This corresponded almost exactly to the point at which the coordination number between Nickel phase particles reached 2.2. The significant finding was that the variation in the value for the conductivity, as measured by the standard deviation of the results, was several orders of magnitude higher than for the simpler systems. We explored the validity of our assumptions, specifically the assumption of random particle placement, by building a particle model directly from FIB-SEM data. In this reconstruction, it was clear that the location of particles was not random. Particles of the same type and size had much likelihood of contact higher than would indicated by random location.

关键词： Resistor network Composite electrodes 3D particle packing Solid oxide fuel cells

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Real-Time Watercolor for Animation

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Journal of Computer Science & Technology 2006年第2期21卷 159-165页

作者： thomas Luft Oliver Deussen Depurtment of Computer and Information Science University of KonstanzKonstanzGermang

We present algorithms that allow for reat-time rendering of 3D-scenes with a watercolor painting appearance,Our approach provides an appropriate simplification of the visual complexity,initates characteristic natural effects of watercolor,and provides two essential painting techniques,the wet-on-wet and the wet-on-dry *** concentrate on efficient algorithms based on image space processing rather than on an exact *** allows for the real-time rendering of *** an animation a high frame-to-frame coherence can be achieved due to a stable segmentation ***,we seamlessly integrate a smooth illumination into the watercolor renderings nsing information from the 3D-scenc.

关键词： non-photorealistic rendering watercolor painting,real-time rendering

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Nanoscale 3D ordered polymer networks

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Science China Chemistry 2018年第1期61卷 25-32页

作者： Edwin L. thomas Department of Materials Science and NanoEngineering Rice University Houston TX 77030 USA

Structures having nanoscale 3D geometries are valuable as multifunctional materials, where multi-continuous microphases can synergistically influence mechanical, optical, transport and other properties. Such very high interface surface to volume ratio structures occur in a variety of materials including natural materials such as butter fly wings and sea urchin exoskeletons and in synthetic self-assembled structures such as surfactant/water systems and block polymers. Quantitative morphological characterization of such complex geometric structures is quite challenging. Unit cell sizes range from 10-300 nm with corresponding feature sizes on the 2-50 nm scale. Since these nanoscale network structures are bicontinuous, when one constituent is removed, the structure is still self supporting. Removal of one component produces a nanoporous material that may be in-filled with another component, or the surfaces of the nanopores can be coated with ultra-thin layers by atomic layer deposition to offer multiftmctional capabilities. Due to the ability to individually tailor the properties of the network（s） and matrix, for example, to create strong dielectric or impedance contrast, such spatially periodic structures are excellent for the interference of waves （electromagnetic for photonic applications and acoustic for phononic applications） that can lead to bandgaps and hence the control of wave propagation in the material. This mini-review will focus on networks formed by bottom up self assembly of block polymers. In addition to structural issues, we emphasize the special physical properties related to bi- or tri-continuous networks.

关键词： self assembly block polymer network morphologies bicontinuous

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DEM parameter calibration of cohesive bulk materials using a simple angle of repose test

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Particuology 2019年第4期17卷 105-115页

作者： thomas Roessler Andre Katterfeld Chair of Material Handling Institute of Logistics and Material Handling Systems University of Magdeburg Universitatsplatz 239106 Magdeburg Germany

The numerical effort of discrete element method (DEM) simulations results in a general idealisation of DEM models that makes the calibration crucial to obtaining realistic simulation results. The angle of repose test has become a standard test for the calibration of DEM parameters of cohesionless bulk materials and is extensively discussed in the literature. One of the most used test methods is the pull-up test of a hollow cylinder filled with bulk material. This paper presents how this basic pull-up test can also be used for the calibration of DEM parameters of cohesive materials by changing the analysis criteria. In contrast to analysing the static angle of repose, the focus lies on the macroscopic flow behaviour during the lifting of the cylinder. Reproducible phases of flow are identified in experiments: the build-up of a stable bulk material column, the convex bending of the column, and the beginning of collapse of the column. Furthermore, the phases are independent of the size and lifting velocity. The convex bending of the bulk-material column combined with the moment of first collapse are introduced as new measurable calibration criteria. These experimental results of wet sand are used for the calibration of related DEM parameters using a simplified JKR cohesion model. The DEM calibration including an analysis algorithm that fits the experimental flow behaviour and the final selection of the relevant parameters (i.e., sliding friction coefficient, rolling friction coefficient, and cohesion energy density) is presented in detail.

关键词： Discrete element method Angle of repose Cohesive bulk material Calibration

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RF channel performance assessment for a multiple carrier millimeter-wave communication system

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Progress in Natural Science:Materials International 2004年第10期14卷 45-48页

作者： thomas WONG Chicago Department of Electrical and Computer Engineering Illinois Institute of Technology Illinois60616 U.S.A

Channel capacity,system versatility and ease of maintenance are factors of prime concern in future generations of wire-less communication *** a result,millimeter-wave can offer considerable advantages in providing broadband *** and noise effects,including parametric fluctuations,are two significant causes for signal degradation in broadband communication *** methods to assess the performance of an RF channel in a multi-carrier system are *** measuring the forward transfer func-tion from transmitter IF to receiver IF as the frequency is swept across the channel bandwidth,characteristics such as gain flatness,chan-nel dispersion,and saturation effects are *** evaluate the ability of the communication link in preserving the synchronization be-tween two carriers,their heterodyned spectrum at the receiver IF output is *** measurement methods employ standard equip-ment and have been found to be effective when applied to a multi-carrier millimeter-wave system with over1GHz instantaneous band-width.

关键词： millimeter-wave communication system multiple carrier intermodulation carrier fluctuation synchronization

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