Theoretical Mode Research Articles

Interface contact pressure-based virtual gradient material model for the dynamic analysis of the bolted joint in machine tools

Bolted joints have significant influence on the dynamic characteristic of the machine tool assembly. This study proposes a new modeling method using virtual gradient material. On the basis of Hertz contact theory and fractal geometry theory, the relationship between contact stiffness and normal contact load is deduced. The contact pressure distribution at the interface is obtained through finite element contact analysis. An orthogonal material model is introduced to describe the properties of virtual material. The virtual material is divided into several layers, and the elastic modulus and shear modulus in each sub-layer are derived based on Hooke’s Law. Both experimental and theoretical results for a bolted lap structure are obtained. The experimental results are compared with theoretical ones in terms of qualitative comparison of similar mode shapes and quantitative comparison of corresponding natural frequencies. The comparison shows that the theoretical first three-order vibration mode shapes are in good line with the experimental ones. The relative errors of corresponding natural frequencies between the virtual gradient material model and the experiment are less than 9%, which are smaller than those between the traditional virtual uniform material model and the experiment. The proposed virtual gradient material method would be useful to accurately model the bolted joint in CNC machine tools.

A High-Sensitivity Micromechanical Electrometer Based on Mode Localization of Two Degree-of-Freedom Weakly Coupled Resonators

This paper reports a high-sensitivity resonant electrometer based on the mode localization of two degree-of-freedom weakly coupled resonators (WCRs). When charges are applied to the input electrodes, the effective stiffness of a specific resonator of the WCRs will be perturbed, leading to a drastic change in mode shape owing to the mode localization phenomenon. By measuring the shift of the amplitude ratio, the small charge fluctuation can be accurately sensed. The theoretical mode of the electrometer is established based on the transfer functions of the WCRs. In particular, we establish the design rules of the coupling factor according to the −3-dB bandwidth, amplitude ratio measurement errors, and frequency misalignment between the resonators. The experimental results show that the amplitude ratio-based sensitivity is $\sim 2151$ times higher than the frequency-based sensitivity. The amplitude ratio-based resolution of the electrometer is approximately 1.269 fC . [2016-0119]

Thermo-optic effects in on-chip lithium niobate microdisk resonators.

We report the experimental observation and theoretical analysis of thermo-optic effects in high-Q on-chip lithium-niobate (LN) microdisks. We find that the resonance transmission dip of a LN microdisk was broadened or compressed when the wavelength of the input laser was tuned to the shorter or the longer wavelengths at a wavelength sweeping speed of 4.8 pm/s. When the laser wavelength was shifted with a fast rate (4.8 nm/s), the tendencies of the change in the shape of the transmission dip reverse completely. An oscillatory behavior in the transmission spectra was also observed when the laser wavelength was slowly shifted to the shorter wavelengths. The experimental results were successfully explained by using a theoretical mode considering for a fast thermo-optic effect of LN crystal and a slow heat dissipation process from the LN microdisk to the substrate and surroundings that leads to the reduction of the resonance wavelength through the deformation of the LN microdisk.

Asteroseismology of theδScuti star HD 50844

Aims. We aim to probe the internal structure and investigate more detailed information of the $\delta$ Scuti star HD 50844 with asteroseismology. Methods. We analyse the observed frequencies of the $\delta$ Scuti star HD 50844 obtained by Balona (2014), and search for possible multiplets based on the rotational splitting law of g-mode. We tried to disentangle the frequency spectra of HD 50844 by means of the rotational splitting only. We then compare them with theoretical pulsation modes, which correspond to stellar evolutionary models with various sets of initial metallicity and stellar mass, to find the best-fitting model. Results. There are three multiplets including two complete triplets and one incomplete quintuplet, in which mode identifications for spherical harmonic degree $l$ and azimuthal number $m$ are unique. The corresponding rotational period of HD 50844 is found to be 2.44$^{+0.13}_{-0.08}$ days. The physical parameters of HD 50844 are well limited in a small region by three modes identified as nonradial ones ($f_{11}$, $f_{22}$, and $f_{29}$) and by the fundamental radial mode ($f_{4}$). Our results show that the three nonradial modes ($f_{11}$, $f_{22}$, and $f_{29}$) are all mixed modes, which mainly represent the property of the helium core. The fundamental radial mode ($f_{4}$) mainly represents the property of the stellar envelope. In order to fit these four pulsation modes, both the helium core and the stellar envelope must be matched to the actual structure of HD 50844. Finally, the mass of the helium core of HD 50844 is estimated to be 0.173 $\pm$ 0.004 $M_{\odot}$ for the first time. The physical parameters of HD 50844 are determined to be $M=$ 1.81 $\pm$ 0.01 $M_{\odot}$, $Z=$ 0.008 $\pm$ 0.001. $T_{\rm eff}=$ 7508 $\pm$ 125 K, log$g=$ 3.658 $\pm$ 0.004, $R=$ 3.300 $\pm$ 0.023 $R_{\odot}$, $L=$ 30.98 $\pm$ 2.39 $L_{\odot}$.

A facile and precise method for quantifying small–large/light-weighted molecular interaction system

It is significant to quantify the intermolecular physisorption extent in biomedical field. By taking the advantage of a significant difference from either sizes or weights, we introduced a combination of Scatchard equation and either ultracentrifugation or size exclusion chromatography to obtain both the binding constant and the number of binding sites by using bovine serum albumin and eosin B as models. Compared to the photoluminescence quenching-based methods like Stern–Volmer and Hill equations, the introduced method is not only more precise but also simpler and more straightforward for the operation. Moreover, the protein conformational changes and the corresponding theoretical binding mode with an atomic resolution were also studied by using three-dimensional fluorescence spectroscopy and molecular docking method, respectively. These comparative results could help scientists select right methods to study any interactions between two molecules with significant differences from either sizes or weights.

Mechanism of sand body prediction in a continental rift basin by coupling paleogeomorphic elements under the control of base level

Abstract In view of the complex sandbody distribution in continental rift basins, a sandbody prediction method is proposed based on the coupling of three core paleogeomorphic elements, provenance system, channel system, and slope break system, which composes the process of “provenance-transport-sedimentation” controlled by base level. The sand body prediction method takes the base level as the lever, the equilibrium position near the lake basin edge as the supporting point, and the core paleogeomorphic elements as study objects, lays stress on the fact that dynamic factors controlling static factors, and takes full consideration of flow state conversion and sandbody genesis. The core paleogeomorphic elements have eight types of theoretical coupling modes, corresponding to coupling deposition effect from the worst to the optimal. During fluctuations of base level, the coupling modes of the core paleogeomorphic elements in continental rift basins change under the “seesaw effect”, as a result, the migration pattern, sedimentary environment, and genesis of sand body change significantly, which control sand body distribution in turn. The sand body development regularity of the Gaoyou Sag in Northern Jiangsu Basin and the Weixinan Sag in Beibu Gulf Basin has been analyzed based on this sand control mechanism and a good prediction result of sand body is achieved, which confirms the validity and practicality of the sand control mechanism.

A Model for the Complete Radial Structure of the Tropical Cyclone Wind Field. Part II: Wind Field Variability

Abstract Part I of this work developed a simple physical model for the complete radial structure of the low-level azimuthal wind field in a tropical cyclone that compared well with observations. However, wind field variability in the model is tied principally to its external parameters given by the maximum wind speed and the radius of maximum wind, the latter of which lacks a credible independent physical model for its variability. Here the authors explore the modes of variability that arise from the alternative specification of the model, which takes the outer radius in lieu of the radius of maximum wind. Nondimensionalization of the model reveals two theoretical modes of structural variability in absolute angular momentum that are shown to closely match observations. These two modes correspond to three modes of wind field variability associated with variations in intensity, outer storm size, and latitude. These wind field modes are demonstrated to mirror the dominant modes of variability found in nature, in particular the intrastorm variation of inner-core structure and the interstorm variation of overall storm size. In combination, the model offers a credible physical solution for the complete time-dependent tropical cyclone wind field in conjunction with the external specification of intensity, outer size, and latitude. More broadly, the model offers theoretical and conceptual insight into the nature of the tropical cyclone wind field, including the oft-conflated terms “size” and “structure” and their distinct variabilities.

A case study of winter storm-induced continental shelf waves in the northern South China Sea in winter 2009

This study deals with winter storm-induced continental shelf waves (CSWs) in the northern South China Sea in winter 2009 using tidal gauge data and along-track satellite altimeter data. The results show that the periods of CSWs propagating along the coast from Kanmen to Shuidong are in bands of 62 and 133h. The phase speeds are in a range from 8 to 13ms−1 between Kanmen and Shantou, from 9 to 11ms−1 between Shantou and Huizhou and from 10 to 15ms−1 between Huizhou and Shuidong, respectively. Satellite altimeter captured along-track sea level anomaly during the CSW events. Further analysis using the theoretical cross-shore CSW modes to fit the along-track sea level anomaly data indicates that the first three wave modes play important roles during the CSW events and the first mode is a dominant component.

Effect of ion interactions on the IR spectrum of benzenesulfonate ion. Restoration of sulfonate ion symmetry in sodium benzenesulfonate dimer

Literature data concerning the assignment of IR spectra of benzenesulfonate salts that serve as model compounds for aromatic sulfonate-containing ionomers and polyelectrolytes have been analyzed. The structures and IR spectra of free benzenesulfonate ion and its potassium and sodium salts have been calculated in B3LYP/6-311G(d,p) approximation. The bidentate coordination of counter-ions is energetically favorable for isolated ion pairs. In this coordination, the symmetry of sulfonate ion changes noticeably, which manifests itself as strong splitting of calculated vibrational modes of asymmetric stretching vibrations of SO bonds, Δνas(SO3) = 154 cm−1 (K) and 180 cm−1 (Na). For sodium benzenesulfonate it is thermodynamically favorable to form a dimer (ΔG° = −37.6 kcal/mol) in which the joint effects of monodentate and bidentate coordinated Na cations result in equalization of SO bond lengths and thus a considerable restoration of C3V symmetry of the sulfonate ion. The IR spectrum of the dimer in which Δνas(SO3) splitting is considerably smaller much better matches the experimental spectrum than the spectrum of an isolated ion pair. The major absorption bands in the IR spectrum of sodium benzenesulfonate have been assigned to theoretical vibrational modes of the dimer and, based on visualization of modes, to vibrations of certain bonds in the anion. In particular, the bands at 1200 and 1186 cm−1 have been assigned to νas(SO3), that at 1049 cm−1 to νs(SO3), and those at 628 and 572 cm−1 to δ(oop)s(SO3), and δ(ip)as(SO3), respectively. The strong effect of sulfonate ion environment on the positions of the absorption bands of stretching vibrations of SO bonds makes it necessary to obtain data on exact structures of ion clusters for reliable assignment of absorption bands in experimental IR spectra of real sulfonate-containing systems.

On complexism

Abstract This article responds to Philip Galanter’s essay ‘Complexism and the role of evolutionary art’ to explore complexism in relation to postmodern and generative architecture. Galanter poses complexism as a new theoretical mode that can supercede the divides of modernism/postmodernism and the two cultures (sciences/arts and humanities). The author, rather than promoting complexism, examines it as if from afar, positioning it as our most recent scientifically informed paradigm. She asserts that, in many ways, complexism functions as an ideology permeating realms of cultural and intellectual production. Examples range from contemporary advertising to economic theory, political and economic protests such as the Occupy Movement, to the rhetorical and computational strategies in generative architecture. The author demonstrates that postmodernism in architecture was always theoretically tied to complex systems theory. Further, she connects the vagaries of application and extrapolation of complexity theory, across realms of current-day cultural production, to the definitional vagueness of some of complexism’s key terms (system, selforganization, emergence). Finally, she argues that two collateral effects of complexism are: (1) the promotion of dependence on environmentally damaging computational devices and (2) the socio-economic and environmental expulsions occurring in the global economy, as recently argued by sociologist Saskia Sassen.

Crystal structure and vibrational properties of Cu2ZnSiSe4quaternary semiconductor

The crystal structure of CuZnSiSe semiconductor, grown by the chemical vapor transport method, was determined by the powder and single-crystal X-ray diffraction and shown to be orthorhombic wurtzstannite (space group P mn2). Lattice dynamics of CuZnSiSe is studied by the low-temperature off-resonant polarized and resonant Raman scattering. Out of the total 45 optical vibrational modes allowed by the symmetry, 37 are observed in the spectra and are assigned to the specific lattice eigenmodes based on their polarization properties and a comparison of frequencies with the results of density functional lattice dynamics calculations. Good agreement between theoretical and experimental mode frequencies is established. The vibrational patterns for the most intense spectral lines in experimental spectra as well as pronounced resonant enhancement of Si-related modes are discussed.

Vibration Frequencies and Modes of a Z-Shaped Beam With Variable Folding Angles

In this paper, we investigate the vibration characteristics of a Z-shaped beam with variable folding angles which is used to model a folding wing of a morphing aircraft under the condition of a fixed structure. The governing equations of motions for the Z-shaped beam are formulated. For a specific set of material and geometrical parameters, the first three in-plane and the first two out-of-plane linear frequencies of the Z-shaped beam are theoretically calculated, and validated by the experiments and numerical simulations. Additionally, the theoretical mode shapes at a fixed folding angle are compared to the experimental results and the finite element simulations. The theoretical results agree well with numerical simulations and experiments. The results obtained in this paper are helpful for designing and controlling Z-shaped beam structures, and can also be used as a basis to study the nonlinear dynamics of these structures.

Banks and economic growth in developing countries: What about Islamic banks?

Islamic banks (IBs) have a significant role in the growth of gross domestic product of the developing countries. The Islamic participatory schemes integrate the assets of lenders and borrowers. They allow enable IBs to lend on a longer term basis to create projects with higher risk-return profiles and, thus, to support economic growth. Our investigation examines the contribution of Islamic finance in economic growth. Using a panel data-set, we compare between IBs and conventional banks in their adding to economic growth. We studied a sample of 120 banks between 2005 and 2012. By means of three ordinary least-square regressions, our empirical investigation reveals that the development of non-usurious banks supports economic growth. Moreover, the cooperation between the two financing modes improves economic growth. The integration of this new funding never neglected the role of the conventional method of financing. The practice of IBs is also away from their theoretical mode in terms of participation results.

Defying the Dominant Discourse: Why Contesting Neoliberalism Needs Critical Pedagogy in Economics

This paper argues that economics as the engine of neoliberalism needs critical pedagogy. As exists currently, both the dominant narrative in the economics discipline and the predominant mode of delivery of an economics education mutually reinforce the authority of neoliberalism. The purpose of this paper is to develop the argument that in addition to a pluralist curriculum, and more than simply broadening teaching practices, a counterhegemonic pedagogy is necessary for equipping students with the knowledge they need to exercise their own judgment as future economists, business leaders and policy makers. Beyond opening discussions of alternative theoretical and methodological approaches or diversifying modes of delivery to promote critical thinking, an economics education engaging critical pedagogy will create the space students need to discuss not only the different assumptions about material relations and individual behavior intrinsic to various economic models but the assumed social relations in both the models studied and the construction of which knowledge defines economics as a field of study.

Exploration of the reform in the teaching of nutrition and food hygiene

Nutrition and food hygiene is a specialized main course of preventive medicine, which is of great significance to promoting the all-round development of students. In the teaching practice, we improve the teaching quality of nutrition and food hygiene by strengthening the quality education of the teachers to improve their professional quality, carrying out theoretical and experimental teaching mode reform, such as carrying out its special form and reorganizing the teaching content, some chapters of the course selection of PBL teaching, optimizing experiment content, increasing the design of experiments, and at the same time changing the traditional assessment methods. Key words: Nutrition and food hygiene; Teaching method; Teaching reform

Efficient Energy Harvesting Using Piezoelectric Compliant Mechanisms: Theory and Experiment

Piezoelectric energy harvesters typically perform poorly in the low frequency, low amplitude, and intermittent excitation environment of human movement. In this paper, a piezoelectric compliant mechanism (PCM) energy harvester is designed that consists of a polyvinylidene diflouoride (PVDF) unimorph clamped at the base and attached to a compliant mechanism at the tip. The compliant mechanism has two flexures that amplify the tip displacement to produce large motion of a proof mass and a low frequency first mode with an efficient (nearly quadratic) shape. The compliant mechanism is fabricated as a separate, relatively rigid frame with flexure hinges, simplifying the fabrication process, and surrounding and protecting the piezoelectric unimorph. The bridge structure of the PCM also self-limits the response to large amplitude impacts, improving the device robustness. Experiments show that the compliant hinge stiffness can be carefully tuned to approach the theoretical high power output and mode shape efficiency.

エイコ＆コマのDelicious Movement Workshopの検討 2

A dance unit called “Eiko&Koma” by Eiko Otake and Takashi Otake has been an extremely highly-admired artist in American dance community for more than 40 years. Eiko&Koma has been creating their own workshop style called “Delicious Movement Workshop” (DMW). By using the qualitative research approach (GTA), this paper aims to grasp the basic characteristics of Eiko’s instructional words toward the students in the two basic programs (called “scores”) of DMW, “Sleeping” and “Sleeping Together”, which will intensify and deepen the understanding of DMW structures, and also provides the knowledge related to the instructional words which the physical expression educators can refer to. In the result, through the case studies, we extracted 4 core categories such as [Time(successive)], [Relationship between Oneself and Others], [Image of Nature ], [Consciousness toward Body] and 8 concepts and we linked them into a theoretical mode (Eiko’s words’structure model). From these results, it became apparent that Eiko’s “instructional words” functions as an important tool to induce the creative and expressive movements from the students. The words dissolves the students’ daily senses toward the body and lead them to the unusual, non-daily life world.

HSAF-induced antifungal effects in Candida albicans through ROS-mediated apoptosis.

Heat-stable antifungal factor (HSAF) belongs to polycyclic tetramate macrolactams (PTMs), which inhibits many fungal pathogens and is effective in inhibiting Candida albicans (C. albicans). In this study, we found that HSAF induced the apoptosis of Candida albicans SC5314 through inducing the production of reactive oxygen species (ROS). Nevertheless, we validated the efficacy of HSAF against candidiasis caused by C. albicans in a murine model in vivo, and HSAF significantly improved survival and reduced fungal burden compared to vehicles. A molecular dynamics (MD) simulation was also investigated, revealing the theoretical binding mode of HSAF to the β-tubulin of C. albicans. This study first found PTMs-induced fungal apoptosis through ROS accumulation in C. albicans and its potential as a novel agent for fungicides.

Rationalization of the selectivity between 1,3- and 1,2-migration: a DFT study on gold(i)-catalyzed propargylic ester rearrangement.

Gold catalyzed rearrangement of propargylic esters can undergo 1,3-acyloxy migration to form allenes, or undergo 1,2-acyloxy migration to access gold-carbenoids. The variation in migration leads to different reactivities and diverse cascade transformations. The effect of terminal substituents is very important for the rearrangement. However, it remains ambiguous how terminal substituents govern the selectivity of the rearrangement. This study presents a theoretical model based on the resonance structure of gold activated propargylic ester complexes to rationalize the rearrangement selectivity. Substrates with a major resonance contributor A prefer 5-exo-dig cyclization (1,2-migration), while those with a major resonance contributor B prefer 6-endo-dig cyclization (1,3-migration). This concise model would be helpful in understanding and tuning the selectivity of the metal catalyzed rearrangement of propargylic esters.

H2 Mole Fraction Measurements in a Microwave Plasma Using Coherent Anti-Stokes Raman Scattering Spectroscopy

In an effort to provide insights into the thermochemical composition of a microwave plasma chemical vapor deposition (MPCVD) reactor, the mole fraction of H2 is measured at various positions in the plasma sheath, at pressures of 10 and 30 Torr, and at plasma powers ranging from 300 to 700 W. A technique is developed by comparing the Q(1)01 transition of experimental and theoretical spectra aided by the Sandia CARSFT fitting routine. Results reveal that the mole fraction of H2 does not vary significantly from its theoretical mixture at the parametric conditions examined. Furthermore, the ν″=1→ν′=2 vibrational hot band was searched, but no transitions were found. An analytical explanation for the increase in the temperature of H2 with the introduction of N2 and CH4 is also presented. Finally, because the mole fraction of H2 does not appear to deviate from the theoretical composition, the rotational and translational modes of H2 are shown to be approximately in equilibrium, and therefore, the rotational temperatures may be used to estimate the translational temperatures of H2.