Rigidity Models Research Articles

Design and Development of a Humanoid Robot for Sign Language Interpretation

With an indisputable complexity of communication for hearing and speaking impaired people, most sign language recognition systems utilize virtual reality or onscreen robots. This paper presents the design and development of a special and low-cost humanoid robot that can perform as a sign language interpreter. To the best of our knowledge, this is the first endeavor to fabricate a humanoid robot for Bangla sign language (BdSL) and Medical signs interpretation. Considering the plethora of design criteria and balancing between rigidity and flexibility 3D models of the robotics parts are designed and 3D printed ensuring cost efficiency. With the help of modern fabrication technology, the robot is developed and assembled with proper actuators and circuitry. An image dataset is built comprising 950 images for BdSL recognition and made publicly available. We utilized the Recurrent neural network (RNN) and Convolutional neural network (CNN) for deep learning model establishment and feature extraction from video and image data. The developed humanoid robot has 43 Degrees of freedom (DoF) which includes two 15 DoF hands. It can imitate 16 BdSL alphabets in sign language, can capture a video or image input in real-time from the user, and recognize 10 medical signs and 38 alphabets of BdSL. The learning model for video-based medical sign recognition achieved 87.5% test accuracy. Image-based Bangla sign language recognition achieved an overall test accuracy of 98.19% in our dataset and 93.8% in another available dataset. Compared to the state-of-the-art robotic systems for sign language interpretation, our approach has achieved higher kinematic characteristics, remarkable results in sign recognition, and impressive competency in sign imitation; all at almost 10 times lower cost than the state-of-the-art systems. The results are evidence that our approach is efficient and suitable in helping hearing and speaking impaired people. Moreover, this work initiates a research scope that can be further extended for creating equal opportunities for the hearing and speaking impaired community.

Accurate Stiffness Modeling Method for Flexure Hinges with a Complex Contour Curve

Background: Flexure hinges have certain advantages, such as a simple structure, smooth movement, no need for lubrication, frictionless movement and high precision. The flexure hinge’s transfer of force and displacement relies on its deformation. Thus, stiffness is an important index for evaluating hinge flexibility. Objective: Stiffness analysis of the flexure hinges is necessary to be performed. This paper aims to present a unified stiffness model solving method of the flexible hinges with complex contour curves. Methods: The transfer matrix of a flexure hinge was derived based on balance equations and the virtual work principle with consideration of axial, shear, and bending deformations. The element stiffness matrix of a flexure hinge was obtained from the relationship between the transfer and stiffness matrices. In this manner, the unified formula of element stiffness of a general flexure hinge was established. By using this method, rigidity models of parabolic, corner-filled, and the right circular flexure hinge have been deduced. By taking the right circular flexure hinge as an example, the results obtained using this method were compared with those of methods provided in other studies and the finite element results. Results and Conclusion: The comparison results revealed that the proposed method increases the rigidity accuracy because the effect of the uneven distribution coefficient of shear stress was considered. The stiffness error was within 7%, which demonstrates the validity of this method. In contrast to the other methods, the proposed method can be applied by determining the first integral element stiffness of a common flexible hinge. Moreover, the proposed method provides better commonality, flexibility, and ease of programming. In particular, it is much easier for the flexure hinges with a complex contour curve. Transitivity can be used to calculate the rigidity after the flexure hinge has been divided into subunits, thus making it unnecessary to convert to the global coordinate system.

Effect of joint rigidity on structural behavior of RC buildings

Non-linear static analysis or pushover analysis is now-a –days generally preferred by many researchers to analyse the non-linear behaviour of the structure. Present study includes the effect of joint rigidity on the behaviour of the structure. A building is modeled with 5 and 10 story and designed for gravity and earthquake resistant loads by considering joint rigidity factor as 0 and 1. The analysis is done in both X and Y directions by using pushover analysis in SAP2000 software. Comparison is made between then capacity curves obtained from designed models of rigidity and non-rigidity models. From the results it is concluded that structure designed using joint rigidity has more strength when compared non-rigid joints.

Are would-be authoritarians right? Democratic support and citizens’ left-right self-placement in former left- and right- authoritarian countries

ABSTRACT Conventional wisdom dictates that the more citizens lean towards either end of the ideological spectrum, the lower their support for democracy. The main model pitted against this “rigidity-of-the-extremes model” is the “rigidity-of-the-right model”. This model assumes that rightist citizens are less supportive. This study proposes and empirically demonstrates the validity of an alternative model, which we call “the authoritarian legacy model”. This model predicts that whether leftist or rightist citizens are less supportive of democracy depends on countries’ experience with left- or right-authoritarianism. To evaluate its validity, we present a systematic comparative investigation of the relation between citizens’ ideological and democratic beliefs, using European and World Values Survey data from 38 European countries (N = 105,495; 1994-2008). In line with this model, our analyses demonstrate that democratic support is lowest among leftist citizens in former left-authoritarian countries and among rightist citizens in former right-authoritarian countries. We find that this relation persists even among generations that grew up after authoritarian rule. These findings suggest that traditional ideological rigidity models are unsuitable for the study of citizens’ democratic beliefs.

Monotonicity and rigidity of the $${\mathcal {W}}$$-entropy on $${\mathsf {RCD}} (0,N)$$ spaces

By means of a space-time Wasserstein control, we show the monotonicity of the $${\mathcal {W}}$$ -entropy functional in time along heat flows on possibly singular metric measure spaces with non-negative Ricci curvature and a finite upper bound of dimension in an appropriate sense. The associated rigidity result on the rate of dissipation of the $${\mathcal {W}}$$ -entropy is also proved. These extend known results even on weighted Riemannian manifolds in some respects. In addition, we reveal that some singular spaces will exhibit the rigidity models while only the Euclidean space does in the class of smooth weighted Riemannian manifolds.

Rigidity and exotic models for v_1-local G-equivariant stable homotopy theory

We prove that the v_1-local G-equivariant stable homotopy category for G a finite group has a unique G-equivariant model at p=2. This means that at the prime 2 the homotopy theory of G-spectra up to fixed point equivalences on K-theory is uniquely determined by its triangulated homotopy category and basic Mackey structure. The result combines the rigidity result for K-local spectra of the second author with the equivariant rigidity result for G-spectra of the first author. Further, when the prime p is at least 5 and does not divide the order of G, we provide an algebraic exotic model as well as a G-equivariant exotic model for the v_1-local G-equivariant stable homotopy category, showing that for primes p ge 5 equivariant rigidity fails in general.

Sensitivity of Probabilistic Tsunami Hazard Assessment to Far-Field Earthquake Slip Complexity and Rigidity Depth-Dependence: Case Study of Australia

Probabilistic Tsunami Hazard Assessment (PTHA) often proceeds by constructing a suite of hypothetical earthquake scenarios, and modelling their tsunamis and occurrence-rates. Both tsunami and occurrence-rate models are affected by the representation of earthquake slip and rigidity, but the overall importance of these factors for far-field PTHA is unclear. We study the sensitivity of an Australia-wide PTHA to six different far-field earthquake scenario representations, including two rigidity models (constant and depth-varying) combined with three slip models: fixed-area-uniform-slip (with rupture area deterministically related to magnitude); variable-area-uniform-slip; and spatially heterogeneous-slip. Earthquake-tsunami scenarios are tested by comparison with DART-buoy tsunami observations, demonstrating biases in some slip models. Scenario occurrence-rates are modelled using Bayesian techniques to account for uncertainties in seismic coupling, maximum-magnitudes and Gutenberg-Richter b-values. The approach maintains reasonable consistency with the historical earthquake record and spatially variable plate convergence rates for all slip/rigidity model combinations, and facilitates partial correction of model-specific biases (identified via DART-buoy testing). The modelled magnitude exceedance-rates are tested by comparison with rates derived from long-term historical and paleoseismic data and alternative moment-conservation techniques, demonstrating the robustness of our approach. The tsunami hazard offshore of Australia is found to be insensitive to the choice of rigidity model, but significantly affected by the choice of slip model. The fixed-area-uniform-slip model produces lower hazard than the other slip models. Bias adjustment of the variable-area-uniform-slip model produces a strong preference for ‘compact’ scenarios, which compensates for a lack of slip heterogeneity. Thus, both heterogeneous-slip and variable-area-uniform-slip models induce similar far-field tsunami hazard.

Labor Market Institutions and Performance Economic Within Trial Labor Market Models: Flexibility, Rigidity, and Flexicurity

The purpose of this article is to identify economic performance through three labor market models (flexibility, rigidity, and flexicurity) that result from the effect of the labor market regulation. After conducting a comparative analysis of the flexibility, rigidity, and flexicurity models of the labor market using a feasible generalized least squares (FGLS) applied to 18 organisation for economic co-operation and development (OECD) countries for the period between 2005 and 2013, we reached the following results. First, the effect of the labor market regulation on the unemployment rate appears to be particularly important for demographic groups (women and young people) on the flexible labor market. The union density and bargaining coverage seem to have the best results in the unemployment rate on the flexible market. More coordinated collective bargaining appears to reduce unemployment on the rigid labor market compared with the flexible one. However, our results are opposed to the neoclassical assertions which suggest that women are excluded from the permanent employment when a strict employment protection legislation (EPL) is excised. We also show that the replacement rate, the duration of unemployment benefits, the active labor market policies, permanent immigration inflows, and the tax wedge seem to have the best results on the flexible labor market, while the other variables have mixed effects on the different models of the labor market. These findings can provide policy makers and regulators with a better understanding of the performance of the flexible labor market and its behavior in the face of labor market institutions and adverse economic shocks. In fact, the government should liberalize strict labor laws.

Point-hyperplane frameworks, slider joints, and rigidity preserving transformations

A one-to-one correspondence between the infinitesimal motions of bar-joint frameworks in Rd and those in Sd is a classical observation by Pogorelov, and further connections among different rigidity models in various different spaces have been extensively studied. In this paper, we shall extend this line of research to include the infinitesimal rigidity of frameworks consisting of points and hyperplanes. This enables us to understand correspondences between point-hyperplane rigidity, classical bar-joint rigidity, and scene analysis. Among other results, we derive a combinatorial characterization of graphs that can be realized as infinitesimally rigid frameworks in the plane with a given set of points collinear. This extends a result by Jackson and Jordán, which deals with the case when three points are collinear.

Thermal analysis of cadmium addition on the glass transition and crystallization kinetics of Se–Te–Sn glassy network

Calorimetric measurements have been performed in quaternary glassy system Se78−xTe20Sn2Cdx (x = 0, 2, 4, and 6) to study the thermally induced glass transition and crystallization phenomena. The characteristics kinetic temperatures (glass transition temperature $$T_{\text{g}}$$ , onset crystallization temperature $$T_{\text{o}}$$ , peak crystallization temperature $$T_{\text{c}}$$ ) and static melting temperature $$T_{\text{m}}$$ of the quaternary glassy series have been determined using their non-isothermal DSC curves. These temperatures were utilized to calculate the thermal stability $$S$$ and the Hruby parameter $$H_{\text{R}}$$ for the studied glasses. Both the activation energy of glass transition $$E_{\text{t}}$$ and the activation energy of crystallization $$E_{\text{c}}$$ for all compositions were evaluated using the well-known Kissinger's relation and the method of Augis–Bennett. Values of the fragility index $$m$$ and the crystallization rate factor $$K_{\text{p}}$$ were estimated using the activation energy values $$E_{\text{t}}$$ and $$E_{\text{c}}$$ , respectively. The compositional dependence of the above-mentioned parameters was discussed on the basis of rigidity models and according to the formation of iono-covalent bonds when our glassy Se–Te–Sn system is doped with a heavy element as Cd.

Analytical Models for Effective Flexural Rigidity of Concrete Segments and Joints

The transverse flexural rigidities of segments and joints have an important influence on internal force distribution of segmental ring. Computing models for force balances on joints of concrete segments are proposed to determine the ultimate bending moment of segment joint. The ultimate curvature, while the bending moment of segment joint reaches ultimate value, is analytically derived based on similarity criterions of strains in beam section. The effective flexural rigidity models of segments and joints are analytically proposed. The investigation shows that the effective flexural rigidity ratio between segment joint and intact segments ranges from 8% to 10%. The segment joint can be simplified as a hang in internal force computing of segment lining ring.

Determination of Weight Suspension Rigidity in the Transport-Erector Aggregates

Целью работы является определение жесткости подвески груза в агрегатах, предназначенных для выполнения транспортно-установочных технологических операций на стартовых комплексах различного назначения.

Evaluation of CFD Simulation Using Various Turbulence Models for Wind Pressure on Buildings Based on Wind Tunnel Experiments

Various Reynolds Average Numerical Simulation (RANS) turbulent models of Computational Fluid Dynamics (CFD) are widely used in numerical simulation of wind environment with buildings areas, but none of them is the most accurate or applicable one. In order to evaluate different numerical simulation models, wind tunnel experiments were designed to validate the results of numerical simulations. Rigidity models surface pressure measurements were employed to get pressure values on several building surfaces among buildings, which accurately assessed different simulating results of wind field effects on buildings. By comparing and validating turbulent models with measurements of wind tunnel experiments, useful guidelines and references were given to choose appropriate turbulent model for numerical wind environment researches and practical application. This study presents the RNG k- model including the DVM treatment has a relative good predicting for both the plan view of velocity contour and the surface pressure. In addition, the Spalart-Allmaras models can be more appropriate predicting results for surface pressure measurements among all models, but its reliability of buildings wind environment prediction is not cleared yet. The future work will be needed.

How Frequent Are Small Price Changes?

Recent empirical work suggests that small price changes are relatively common. This evidence has been used to criticize classic menu-cost models. In this paper, we use scanner data from a national supermarket chain and micro data from the Consumer Price Index to reassess the importance of small price changes. We argue that the vast majority of these changes are due to measurement error. We conclude that the evidence on the prevalence of small price changes is much too weak to be used as a litmus test of nominal rigidity models. (JEL C82, E31, L11, L81)

Rigidity and exotic models for theK–local stable homotopy category

Can the model structure of a stable model category be recovered from the triangulated structure of its homotopy category? This paper introduces a new positive example for this, namely the K-local stable homotopy at the prime 2. For odd primes, however, this is not true: we discuss a counterexample given by Jens Franke and show how such exotic models for the K-local stable homotopy category at odd primes can be detected.

Uplift of Beta Regio: Three‐dimensional models

Three‐dimensional models of the uplift of Beta Regio caused by a mantle plume satisfy constraints on gravity, topography, rheology, and the uplift rate substantially better than two‐dimensional models. In particular, the uplift time of Beta Regio is reduced to an acceptable 800 million years. Three‐dimensional models give the plume formation depth around 3000 km, which approximately corresponds to the core‐mantle boundary. The results depend only weakly on the initial lithospheric thickness (at the time of global resurfacing), including a very thin initial lithosphere. This implies that the thick present‐day lithosphere (∼400 km) suggested by our models can be reconciled with a thin lithosphere (100–200 km) inferred from the melt generation rates and the flexural rigidity models.

The space-developed dynamic vertical cutoff rigidity model and its applicability to aircraft radiation dose

We have developed a dynamic geomagnetic vertical cutoff rigidity model that predicts the energetic charged particle transmission through the magnetosphere. Initially developed for space applications, we demonstrate the applicability of this library of cutoff rigidity models for computing aircraft radiation dose. The world grids of vertical cutoff rigidities were obtained by particle trajectory tracing in a magnetospheric model. This reference set of world grids of vertical cutoff rigidities calculated for satellite altitudes covers all magnetic activity levels from super quiet to extremely disturbed (i.e., Kp indices ranging from 0 to 9+) for every three hours in universal time. We utilize the McIlwain “L” parameter as the basis of the interpolation technique to reduce these initial satellite altitude vertical cutoff rigidities to cutoff rigidity values at aircraft altitudes.

The limitations of using vertical cutoff rigidities determined from the IGRF magnetic field models for computing aircraft radiation dose

Vertical cutoff rigidities derived from the International Geomagnetic Reference Fields (IGRF) are normally used to compute the radiation dose at a specific location and to organize the radiation dose measurements acquired at aircraft altitudes. This paper presents some of the usually ignored limits on the accuracy of the vertical cutoff rigidity models and describes some of the computational artifacts present in these models. It is noted that recent aircraft surveys of the radiation dose experienced along specific flight paths is sufficiently precise that the secular variation of the geomagnetic field is observable.

Experimental evaluation of various rigidity models

Atmospheric cosmic-ray fluxes have recently been measured over large portions of the globe on a series of flights of a United States Air Force jet aircraft. The measured fluxes have been plotted as a function of the vertical cutoff rigidity for several different models. The rigorous trajectory calculations of Shea et al. give good agreement with the counting rates. The Makino model also orders these data equally well and therefore must be within a few percent of the value determined by rigorous orbit calculations taken over the portions of the globe covered in this survey. The other models are demonstrably worse, and a discussion of where these models are inadequate is given. Particular attention is paid to the use of the L parameter as a substitute for rigorous integration procedures. It is shown both experimentally and theoretically that the L parameter is not a good demographic parameter for galactic cosmic radiation at the lower latitudes, but it should be sufficiently accurate at higher latitudes for most purposes.