Size Square Research Articles

Anchor Loss Reduction in Micro-Electro Mechanical Systems Flexural Beam Resonators Using Trench Hole Array Reflectors.

The quality factor of microelectromechanical resonators is a crucial performance metric and has thus been the subject of numerous studies aimed at maximizing its value by minimizing the anchor loss. This work presents a study on the effect of elastic wave reflectors on the quality factor of MEMS clamped-clamped flexural beam resonators. The elastic wave reflectors are a series of holes created by trenches in the silicon substrate of the resonators. In this regard, four different shapes of arrayed holes are considered, i.e., two sizes of squares and two half circles with different directions are positioned in proximity to the anchors. The impact of these shapes on the quality factor is examined through both numerical simulations and experimental analysis. A 2D in-plane wave propagation model with a low-reflecting fixed boundary condition was used in the numerical simulation to predict the behavior, and the MEMS resonator prototypes were fabricated using a commercially available micro-fabrication process to validate the findings. Notably, the research identifies that half-circle-shaped holes with their curved sides facing the anchors yield the most promising results. With these reflectors, the quality factor of the resonator is increased by a factor of 1.70× in air or 1.72× in vacuum.

Analysis of Influencing Factors for Stackable and Expandable Acoustic Metamaterial with Multiple Tortuous Channels.

To reduce the noise generated by large mechanical equipment, a stackable and expandable acoustic metamaterial with multiple tortuous channels (SEAM-MTCs) was developed in this study. The proposed SEAM-MTCs consisted of odd panels, even panels, chambers, and a final closing plate, and these component parts could be fabricated separately and then assembled. The influencing factors, including the number of layers N, the thickness of panel t0, the size of square aperture a, and the depth of chamber T0 were investigated using acoustic finite element simulation. The sound absorption mechanism was exhibited by the distributions of the total acoustic energy density at the resonance frequencies. The number of resonance frequencies increased from 13 to 31 with the number of layers N increasing from 2 to 6, and the average sound absorption coefficients in [200 Hz, 6000 Hz] was improved from 0.5169 to 0.6160. The experimental validation of actual sound absorption coefficients in [200 Hz, 1600 Hz] showed excellent consistency with simulation data, which proved the accuracy of the finite element simulation model and the reliability of the analysis of influencing factors. The proposed SEAM-MTCs has great potential in the field of equipment noise reduction.

Energy absorption analysis of square-circle hybrid section tubes under axial loading

Square-circle hybrid section (SCHS) tubes under axial loading which combine the advantage of square tubes and circular tubes are investigated. Firstly, effective finite element models of SCHS tubes are established to study the crashworthiness characteristics. Through a series of finite element models, the influence of the geometry on the behaviour of crashworthiness is studied, including relative size of square and circular sections in SCHS tubes and the position of connecting plates. The results show that compared with corresponding traditional multi-cell tubes, SCHS tubes improve the performance in energy absorption, with a maximum increase of 40.49%, while reducing peak force and improving crushing load efficiency. Moreover, the deformation of elements constituting the SCHS tube is analysed, and deformation of arc-plate elements could be classified into three typical modes. According to the observed deformation modes, the theoretical model is proposed to predict the mean crushing force of SCHS tubes. The theoretical results show that it is in good agreement with the numerical results.

Effect of MWCNT particles on wear loss in dry sliding wear of PEEK matrix composites

Abstract In present circumstances nano particles reinforced with polymer matrix composites (PMC) are used for plentiful applications. Poly-ether-ether-ketone (PEEK) is enactment thermoplastic which have been used extensively in many engineering applications due their excellent mechanical, thermal electrical properties and wears resistance. Multi Wall Carbon Nano Tubes (MWCNT) reinforced PMCs can improve the properties of matrix material in terms of frictional resistance and tensile strength. In the current research, the wear performance of MWCNT reinforced PEEK matrix composites is examined using the pin-on-disk apparatus under dry condition. The wear parameters such as load, sliding speeds, temperature and wt % MWCNT are considered to evaluate wear loss in the composites. The MWCNT reinforced PEEK matrix composites were prepared by using melt mixing technique. Machining and polishing operations were used to make the pin size of square 8 mm and height 30 mm. Response surface design is engaged to perform the experiments. After wear test the worn out surfaces are studied through scanning electron microscopy.

A High-Capacity Reversible Watermarking Scheme Based on Shape Decomposition for Medical Images

We present a high-capacity reversible, fragile, and blind watermarking scheme for medical images in this paper. A bottom-up saliency detection algorithm is applied to automatically locate the multiple arbitrarily-shaped regions of interest (ROIs). The iterative square-production algorithm is developed to generate different sizes of squares for shape decomposition on the regions of noninterest (RONIs). This scheme of combining the frequency-domain watermarking and arbitrarily-shaped ROI methods can significantly increase the watermarking capacity, whereas the embedded image fidelity is preserved. Extensive experiments were carried out on the OASIS medical image dataset, which consists of a cross-sectional collection of 416 subjects, aged from 18 to 96 years old. The results show that the proposed scheme outperforms six existing state-of-the-art schemes in terms of watermarking capacity and embedded image fidelity.

Magnetostatic spin wave resonance in square-patterned Ni0.77Fe0.16Cu0.05Cr0.02 (Mu-metal) thinfilms

Behavior of spin waves was investigated in patterned Mu-metal thin film both theoretically and experimentally. The Mu-metal(111) thinfilms with 7nm thickness were grown by thermal evaporation technique in high vacuum condition. X-ray diffraction measurements showed that the film has a highly FCC crystalline structure. Saturation magnetization and coercive field values of sample obtained from vibrating sample magnetometer are around 500emu/cm3 and 10Oe respectively at room temperature. The patterns were square shaped and size of squares were changed between 40–80µm. Theoretical model and computer program were developed for analyzing the FMR spectra. There is no magnetic anisotropy for in-plane and out-of-plane geometry by both theoretical and experimental investigations. Magnetostatic modes were observed for out-of-plane geometry and these modes were highly compatible with outputs of simulation model.

Optimal Spatial Filtering Schemes and Compact Tomography Setups

ABSTRACTThree compact computerized tomography (CT) scanner prototypes are established and tested for acceptable reconstruction results. Performance of conventional iterative reconstruction algorithm is enhanced via incorporating a spatial filtering/masking step. Generally, these masking strategies incorporate an arbitrary (3 3 or 2 2) size of square averaging mask to subdue the ill-posedness. Three different spatial filtering schemes are tested in this work. The objective is to remove any dependency on a user for deciding an appropriate masking parameter. The outcome of the simulation study is successfully verified for three real data situations using three specimens with pre-assigned/known inner profile. Such austere scanning situations arise in real-time environment especially for undetachable/fixed small size objects situated in inaccessible locations. The present study encourages the development of low budget CT setups.

Bone marrow-derived mesenchymal cells feature selective migration behavior on submicro- and nano-dimensional multi-patterned substrates

This study investigated whether cells have an intrinsic ability to recognize nanopatterns, which could lead to their accumulation or diminution on a biomaterial. A multi-patterned “biochip” was made, containing 36 differently designed surfaces, including squares and grooves varying in feature sizes between 10 and 1000nm. The grooved patterns could additionally be subdivided into three groups having ridge to groove ratios of 1:1, 1:3 and 3:1. These substrates were used for culture of rat bone marrow derived mesenchymal cells. In time cells should accumulate on patterns of preference, while migrating away from patterns of disfavor. A regression analysis model was designed for the analysis of the obtained data.Results showed that strong differences existed between the tested patterns regarding the cellular affinity. All sizes of squares showed strong cell-repelling capacity, with the biggest sized squares displaying up to 40% less cells compared to the smooth surface. Among the nano-grooved patterns cell repelling was seen for the grooves with the ridge to groove ratio of 1:3, while grooves with the ridge to groove ratio of 3:1 partially showed cell attraction. Such effects were shown to be based on selective migration rather than proliferation.In conclusion, the use of a multi-patterned biochip setup allows for enhanced evaluation of cell behavior, as compared to uniformly patterned setups. Cells exhibit the ability to actively avoid or migrate to surfaces featuring certain topographies on nanometric scale. Such phenomena may be utilized for the development of biomaterials in regenerative medicine.

Effect of feature size on dielectric nonlinearity of patterned PbZr0.52Ti0.48O3 films

Lead zirconate titanate, PZT (52/48), thin films with a PbTiO3 seed layer were patterned into features of different widths, including various sizes of squares and 100 μm, 50 μm, and 10 μm serpentine designs, using argon ion beam milling. Patterns with different surface area/perimeter ratios were used to study the relative importance of damage produced by the patterning. It was found that as the pattern dimensions decreased, the remanent polarization increased, presumably due to the fact that the dipoles near the feature perimeter are not as severely clamped to the substrate. This investigation is in agreement with a model in which clamping produces deep wells, which do not allow some fraction of the spontaneous polarization to switch at high field. The domain wall mobility at modest electric fields was investigated using the Rayleigh law. Both the reversible, εinit, and irreversible, α, Rayleigh coefficients increased with decreasing serpentine line width for de-aged samples. For measurements made immediately after annealing, εinit of 500 μm square patterns was 1510 ± 13; with decreasing serpentine line width, εinit rose from 1520 ± 10 for the 100 μm serpentine to 1568 ± 23 for the 10 μm serpentine. The irreversible parameter, α, for the square patterns was 39.4 ± 3.2 cm/kV and it increased to 44.1 ± 3.2 cm/kV as the lateral dimension is reduced. However, it was found that as the width of the serpentine features decreased, the aging rate rose. These observations are consistent with a model in which sidewall damage produces shallow wells that lower the Rayleigh constants of aged samples at small fields. These shallow wells can be overcome by the large fields used to measure the remanent polarization and the large unipolar electric fields typically used to drive thin film piezoelectric actuators.

On the initiation of sustained slip-weakening ruptures by localized stresses

Numerical simulations of dynamic earthquake rupture require an artificial initiation procedure, if they are not integrated in long-term earthquake cycle simulations. A widely applied procedure involves an ‘overstressed asperity’, a localized region stressed beyond the static frictional strength. The physical properties of the asperity (size, shape and overstress) may significantly impact rupture propagation. In particular, to induce a sustained rupture the asperity size needs to exceed a critical value. Although criteria for estimating the critical nucleation size under linear slip-weakening friction have been proposed for 2-D and 3-D problems based on simplifying assumptions, they do not provide general rules for designing 3-D numerical simulations. We conduct a parametric study to estimate parameters of the asperity that minimize numerical artefacts (e.g. changes of rupture shape and speed, artificial supershear transition, higher slip-rate amplitudes). We examine the critical size of square, circular and elliptical asperities as a function of asperity overstress and background (off-asperity) stress. For a given overstress, we find that asperity area controls rupture initiation while asperity shape is of lesser importance. The critical area obtained from our numerical results contrasts with published theoretical estimates when background stress is low. Therefore, we derive two new theoretical estimates of the critical size under low background stress while also accounting for overstress. Our numerical results suggest that setting the asperity overstress and area close to their critical values eliminates strong numerical artefacts even when the overstress is large. We also find that properly chosen asperity size or overstress may significantly shorten the duration of the initiation. Overall, our results provide guidelines for determining the size of the asperity and overstress to minimize the effects of the forced initiation on the subsequent spontaneous rupture propagation.

Proportionate growth in patterns formed in the rotor-router model

We study the growing patterns formed in the rotor-router model by adding N walkers at the centre of an L × L two-dimensional square lattice, starting with a periodic background of arrows, and relaxing to a stable configuration. The pattern is made of a large number of triangular and quadrilateral regions, where in each region all arrows point in the same direction. We show that the pattern formed by arrows which have been rotated at least one full circle may be described in terms of a tiling of the plane by squares of different sizes. The sizes of these squares, and the size of the pattern, grow linearly with N for 1 ≪ N < 2L. We use the Brooks–Smith–Stone–Tutte theorem relating tilings of squares by smaller squares to resistor networks, to determine the exact relative sizes of these tiles for large N. The scaling limit of the number of visits φ(ξ, η) as a function of the scaled position (ξ, η) is also determined. We also present numerical evidence that the deviations of the sizes of the different squares in the tiling from the asymptotic linear growth law are always O(1), and are quasiperiodic functions of N.

Effects of non-symbolic numerical information suggest the existence of magnitude–space synesthesia

In number-space synesthesia, numbers are visualized in spatially defined arrays. In a recent study (Gertner et al. in Cortex, doi: 10.1016/j.cortex.2012.03.019 , 2012), we found that the size congruency effect (SiCE) for physical judgments (i.e., comparing numbers' physical sizes while ignoring their numerical values, for example, 8) was modulated by the spatial position of the presented numbers. Surprisingly, we found that the neutral condition, which is comprise solely of physical sizes (e.g., 3), was affected as well. This pattern gave rise to the idea that number-space synesthesia might entail not only discrete, ordered, meaningful symbols (i.e., Arabic numbers) but also continuous non-symbolic magnitudes (i.e., sizes, length, luminance, etc.). We tested this idea by assessing the performance of two number-space synesthetes and 12 matched controls in 3 comparative judgment tasks involving symbolic and non-symbolic stimuli: (1) Arabic numbers, (2) dot clusters, and (3) sizes of squares. The spatial position of the presented stimuli was manipulated to be compatible or incompatible with respect to the synesthetic number-space perceptions. Results revealed that for synesthetes, but not for controls, non-symbolic magnitudes (dot clusters) as well as symbolic magnitudes (i.e., Arabic numbers) interacted with space. Our study suggests that number-space synesthetes might have a general magnitude-space association that is not restricted to concrete symbolic stimuli. These findings support recent theories on the perception and evaluation of sizes in numerical cognition.

Simulation of two-dimensional many-particle hardcore bosons by using the quantum Monte Carlo method

In this paper, the stochastic series expansion quantum Monte Carlo method is employed to investigate the thermodynamic properties of hardcore Bose-Hubbard model in two-dimensional space. The two-dimensional hardcore Bose-Hubbard model can be mapped into the two-dimensional antiferromagnetic quasi-Heisenberg model under transform of bosonic operators. There is an additional term which is proportional to the total number of sites compared with real Heisenberg model and it is difficult for simulation. Using a nonlocal operator-loop update, it allows one to simulate thousands of sites. Our simulation results show that, first, energy decreases with the increase of density of particles in a range from 0 to 0.5, and finally approaches to a fixed value. Moreover, with the size of square lattice increasing, energy also increases. Second, when we fix the system size, energy and magnetization increase with temperature, but not with of chemical potential. When we increase the system size, energy increases, while, the magnetization decreases. Third, specific heat is independent of chemical potential, but it dramatically increases with temperature and approaches to a peak, then decreases slowly. According to Landau theory of superfluidity, the tends of curve for energy and specific heat fit the research of He II in the Landau two-fluid model. Fourth, different square lattice linear system sizes have a little influence on tiny differences to the reciprocal of uniform susceptibility. There are small fluctuations in a range from 0 to 0.5(J/kB), where J is the coupling energy, kB is the Boltzmann constant, but the reciprocal of uniform susceptibility increases with temperature increasing in a range from 0.5 to 2(J/kB). The tends of curve are similar to those of Kondo effect.

A precision-of-information explanation of sensory dominance

Subjects identified letters or judged the sizes of squares presented visually and/or haptically. The stimuli were presented as spatiotemporal patterns (pre-recorded movement pathways) matched to avoid favouring either mode. Visual explorers were shown pathways as either a 1 cm line tracing out the shape (moving window condition) or as a line moving behind a stationary 1 cm window (stationary window condition). Haptic explorers| fingertips were guided along raised-line pathways (moving window condition) or felt the shapes, depicted in raised-line drawings, moving under their static fingertip (stationary window condition). Visual and haptic performance did not differ but the moving window conditions yielded lower latencies than stationary window conditions in both modes. When squares of different sizes were presented simultaneously to vision and kinesthesis, vision was dominant. The reverse was true when tactile (cutaneous) input was added to the kinesthetic information. These findings support the optimal integration hypothesis in that precision of information is critically related to dominance, and they challenge the concept of sensory capture as a modality-specific phenomenon.

Visual and haptic influence on perception of stimulus size

In six experiments, subjects judged the sizes of squares that were presented visually and/or haptically, in unimodal or bimodal conditions. We were interested in which mode most affected size judgments in the bimodal condition when the squares presented to each mode actually differed in size. Three factors varied: whether haptic exploration was passive or active, whether the choice set from which the subjects selected their responses was visual or haptic, and whether cutaneous information was provided in addition to kinesthetic information. To match the task for each mode, visual presentations consisted of a cursor that moved along a square pathway to correspond to the haptic experience of successive segments revealed during exploration. We found that the visual influence on size judgments was greater than the influence of haptics when the haptic experience involved only kinesthesis, passive movement, and a visual choice set. However, when cutaneous input was added to kinesthetic information, size judgments were most influenced by the haptic mode. The results support hypotheses of sensory integration, rather than capture of one sense by the other.

Eliminating redundancy and singularity in robot path planning based on masking

Path tracking in industrial robotics studies has been widely studied by researchers. In this paper, a new method for planning the path is proposed. Squares which called mask are used to build the path based on the desired path. Petri net modeling is used to coordinate joints movement. The size of squares is the same and presets. The robot moves along the diagonal. To track the path correctly the size of the mask has to be set based on variation of the path. The best square size is achieved if there is no more than on path in each mask. The big advantage of this method is eliminating the redundancy and singularity. All joint in a mask are moving and stopping simultaneously. This method guarantee the fast moving as the path is inside the pre build mask and the robot moving is simultaneous with path planning. This is other advantage of this method. The third advantage of this method is eliminating the backlash of actuators. Reducing the inverse kinematic calculations is the last advantage of the method.

Modified bandlet transform with reward prediction of image geometry

With emphasis on total variation being a reward prediction of image geometry, a modified bandlet transform is proposed. The new scheme is more conformed to human vision than the original one. It takes advantage of the sparse distribution of image geometry in the wavelet domain and retransforms wavelet coefficients in a top-to-bottom way. The point is that the searching space for optimal geometries can be refined in advance and the retransform can be constrained within the vicinity of the desired geometry except the ambient space, where it is assumed image geometries exist in all size of squares. Experimental results and complexity analysis validate the improvement of the proposed scheme especially in determination of the optimal image geometry through a decision-making strategy.

Perceiving an object in its context--is the context cultural or perceptual?

S. Kitayama, S. Duffy, T. Kawamura, and J. T. Larsen (2003) found that East Asians, when shown a line inside a square, memorized more accurately the ratio of the line's length relative to the square than the line's absolute length, whereas North Americans showed the opposite results. Because of this study's important implications on cultural influence to visual perception, we attempted to replicate it in China and USA, without success. Our 120 participants as a whole estimated a line's relative length more accurately than its absolute length, regardless of culture. Our results can be explained by the advantage of an explicit frame of reference in the ratio estimation, an advantage well known in the literature. Namely, the square as a frame of reference is more useful in the relative than in the absolute estimation of the line's length when the size of square changed from study to recall.

Estimating stimuli from contrasting categories: Truncation due to boundaries.

In this article, the authors present and test a formal model that holds that people use information about category boundaries in estimating inexactly represented stimuli. Boundaries restrict stimuli that are category members to fall within a particular range. This model posits that people increase the average accuracy of stimulus estimates by integrating fine-grain values with boundary information, eliminating extreme responses. The authors present 4 experiments in which people estimated sizes of squares from 2 adjacent or partially overlapping stimulus sets. When stimuli from the 2 sets were paired in presentation, people formed relative size categories, truncating their estimates at the boundaries of these categories. Truncation at the boundary of separation between the categories led to exaggeration of differences between stimuli that cross categories. Yet truncated values are shown to be more accurate on average than unadjusted values.

Figure and Ground in the Visual Cortex: V2 Combines Stereoscopic Cues with Gestalt Rules

Figure-ground organization is a process by which the visual system identifies some image regions as foreground and others as background, inferring 3D layout from 2D displays. A recent study reported that edge responses of neurons in area V2 are selective for side-of-figure, suggesting that figure-ground organization is encoded in the contour signals (border ownership coding). Here, we show that area V2 combines two strategies of computation, one that exploits binocular stereoscopic information for the definition of local depth order, and another that exploits the global configuration of contours (Gestalt factors). These are combined in single neurons so that the "near" side of the preferred 3D edge generally coincides with the preferred side-of-figure in 2D displays. Thus, area V2 represents the borders of 2D figures as edges of surfaces, as if the figures were objects in 3D space. Even in 3D displays, Gestalt factors influence the responses and can enhance or null the stereoscopic depth information.