Series Of Segments Research Articles

Harnessing the nonlinear properties of buckling inflatable tubes for complex robotic behaviors

Imparting complex behaviors to soft robots generally entails complex designs and carefully engineered structures. As such, making soft structures with behaviors such as stiffening, bistability and rapid snapping deformations generally requires specialized solutions. This work introduces the use of short inflatable tubes that buckle under compression to realize behaviors such as self-stiffening, bistability and snap-through induced rapid deformations. These inflatable tubes have a nonlinear behavior resulting from these tubes having two stable states, the buckled and unbuckled states, and the complex transition between states which entails a snap-through buckling instability during the buckling transition, and a range of deformation where the tube is bistable as it is stable in either the buckled or unbuckled states. This work shows how the dimensions of the inflatable tubes affect this behavior and proposes a numerical model that can describe the entire cyclic behavior of buckling and unbuckling inflatable tubes. It is then demonstrated how simply connected multiple inflatable tube segments in series can be used to produce complex robotic behaviors. A soft robotic hand is demonstrated that uses the characteristics of unbuckling inflatable tubes for self-stiffening, and a grasping tool capable of slow or rapid motions by making use of the ability of serially connected inflatable tubes to transition from bistability to monostability.

Experimental and simulation investigation of vertical response of stepped torsion bar spring for light motor vehicle suspension system

The straight torsion bar spring is widely used in automobile and military tankers suspension systems due to less occupation of space and high weight bearing capacity. In this present work, the vertical response of Stepped Torsion Bar Spring (STBS) in Light Motor Vehicle (LMV) suspension is investigated. The STBS consists of two segments in series. The segment-1 is larger diameter when compared to that of segment-2. Three cases of diameter ratio and length ratios combination of STBS are experimented and simulated. A 2-DOF (Degree of Freedom) quarter car model test rig is designed for the experimental work. A harmonic excitation is given as road input though a Cam. The damped and undamped vertical response and frequencies of STBS are experimented. The vertical response and its spectrum analysis are plotted and better responses of the low stiffness STBS is identified for comfort ride and the results are compared with MATLAB Simulink results. The results of the suspension parameters such as tire stiffness, damping coefficient of shock absorber, stiffness of STBS, internal damping of STBS and torsional to linear stiffness are investigated.

Identification of Quadratic Volterra Polynomials in the “Input–Output” Models of Nonlinear Systems

In this paper, we propose a new algorithm for constructing an integral model of a nonlinear dynamic system of the “input–output” type in the form of a quadratic segment of the Volterra integro-power series (polynomial). We consider nonparametric identification of models using physically realizable piecewise linear test signals in the time domain. The advantage of the presented approach is to obtain explicit formulas for calculating the transient responses (Volterra kernels), which determine the unique solution of the Volterra integral equations of the first kind with two variable integration limits. The numerical method proposed in the paper for solving the corresponding equations includes the use of smoothing splines. An important result is that the constructed identification algorithm has a low methodological error.

FIORA : A Flexible Tendon-Driven Continuum Manipulator for Laparoscopic Surgery

Aiming at solving the problems of low flexibility, poor internal extension, and chopstick effect in most laparoscopic surgical robots, this letter presents a flexible tendon-driven continuum surgical manipulator with eight degrees of freedom, called FIORA. The manipulator is composed of three independent flexible segments in series, and each flexible segment includes 12 spherical joints made of aluminum alloy backbone. The manipulator is driven by twelve tendons and has good flexibility and rigidity. The compact actuation unit can meet the requirements of force and position control for each tendon,and provide two degrees of freedom for the manipulator to move forward and rotate. Considering the shape-position relationship of the continuum, a kinematic modeling method based on piecewise constant curvature model is proposed, which can solve the problems of accurate modeling and fast decoupling. Analyzing and comparing similar researches, the manipulator shows excellent working range and flexibility. Experiments verified the accuracy of the kinematics model and the good operating performance of the manipulator.

ОБ ИДЕНТИФИКАЦИИ КОЭФФИЦИЕНТА ТЕПЛООБМЕНА В СЛОИСТОЙ СРЕДЕ

In the article we consider the well-posedness in Sobolev spaces of the inverse problems of determining the heat exchange coefficient at the interface which is included in the transmission condition of the imperfect contact type. In a cylindrical spatial domain, a second-order parabolic equation is considered. The domain is divided into two sub-domains, on the common part of the boundary of which the transmission condition is set. The heat exchange coefficient included in the transmission condition is sought as end segment in series with time-dependent unknown Fourier coefficients. The equation is supplemented with general boundary conditions and initial conditions, as well as overdetermination conditions. The ovedetermination conditions are the values of a solution at some points lying in the spatial domain. Under natural smoothness conditions for the data and the location of the measurement points, the existence and uniqueness theorem local in time is demonstrated. The obtained solution to the problem is regular, i. e., all generalized derivatives included in the equation are summable to some power, and the equation holds almost everywhere. The method is constructive, and the approach allows to develop numerical methods for solving the problem. The proof is based on a priori estimates obtained and the fixed-point theorem.

A 3D printed hydrostatic skeleton for an earthworm-inspired soft burrowing robot.

Moving through soil is challenging for robots, particularly for soft robots. Herein, we propose a support structure, based on the hydrostatic skeleton of earthworms, to overcome this problem. To create extremely flexible, thin-walled, worm-sized deformed segments, a specialized 3D printer for low-hardness rubber was utilized. To obtain large radial deformation, we investigated the properties of the soft materials for 3D printing and the geometry of the segments. Notably, segments are deformed with multiply-wound shape memory alloy wires. We constructed an earthworm robot by connecting shape memory alloy-driven segments in series and experimentally demonstrated that this robot could propel in the soil. The proposed robot is unique in that it has a small diameter of 10 mm and exhibits a peristaltic motion in soil.

A 3D macro-segment network model for vanadium redox flow battery with serpentine flow field

This paper presents a 3D macro-segment network model for a vanadium redox flow battery with serpentine flow field. The proposed network model is coupled of electrolyte flow module, species transfer module, charge transfer module. In flow resistance network module, the characteristics of electrolyte flow in the serpentine flow channel and under-rib convection in the porous electrode are all considered. In addition, the electrode intrusion and the electrode non-uniform structure caused by compression are taken into account. In species transfer network module, the convection, diffusion and migration between adjacent segments and reversible electrochemical reactions and self-discharge reactions inside the segment are all analyzed in the ion conservation equation. In charge transfer network module, each battery segment, which is composed of the channel, electrode and membrane segment in series, is connected in parallel and has the same output voltage. In this paper, the battery performance including charge-discharge voltages and cell pressure drop under different electrode compression ratios are validated. In the following, the battery performance under single and multiple charge-discharge cycle are investigated using the proposed network model. Besides, the field distribution of key parameters in terms of velocity, pressure, ions concentration and current density are analyzed and validated with finite element method model data. The proposed 3D macro-segment network model is not only able to effectively consider the distribution difference inside the battery caused by the flow field, but also capable of reducing the computational resources, which renders the network model is suitable for the fast prediction of battery performance.

Development of a metric for predicting people's responses to gusting wind noise in automobiles

Automobile manufacturers are trying to improve the interior noise environment in their cars. A more thorough understanding of how people perceive the noise is an important step towards this goal. The focus of the current research is on modeling the acceptability of time-varying wind noises containing gusts. A listening test was designed containing sounds that were simulated on the computer, based on pre-defined airflow profiles. The time-varying noises in the test follow one of two simple gusting scenarios. The primary scenario contained two segments of steady wind flanking a series of consecutive equal-strength gusts. The number, duration, and strength of the gusts were varied between sounds. This was done to examine general trends of acceptability with modulation rate, modulation depth, and duration. The second scenario contained two gusts of equal or unequal strength, occurring either without a break or separated by a time gap. This was done to examine the relationship between people's reactions to the individual gusts in a pattern and their reactions to the whole pattern. A small number of steady-wind noises were included for reference. Terms in an acceptability model containing a previously proposed gusting metric were estimated. Possible refinements to the metric and model are discussed.

Ethnogonic Texts in the Indo-European Tradition

This article examines the texts of the Indo-European tradition, which narrate about the myths of the origin of different peoples. Thus, a segment of the Anglo-Saxon runic series correlates with Tacitus’s description of the origin of the Ingaevon tribe. As a result, the parameters of the ethnically derived text are reconstructed. The parameters explain the choice of the sequence of the runes of the Anglo-Saxon futhork. The restored text testifies that the Ingaevons, who had the totem deity Ing, lived on the shores of the Ocean, and this was their homeland. Ethnogonic texts also tell about the correlation of totem and ethnonym in past eras. The German influence on the choice of the ethnonym “Rus”, determined by the alliterative connection of the name of the country with the name of Rurik’s tribe, has been explained. The “Rurikids” ethnonym itself came from the name of the Rhos tribe. Many ethnogonic texts are associated with sacrificial rituals. In this context, of interest is the name “Italia”, which takes its origin in the sacred texts of the high sacred style. The most ancient Indo-European inscription in the Lusitanian language, written in a high style and telling about the origin of the Veaminikori tribe, is analyzed. The names of sacred animals are opposed to the profane names in the Latin prayer to the god Mars. The souuitaurilia prayer bears witness to the repertoire of sacrificial texts about dairy animals. As a result, it becomes clear that the name “Italy” is derived from the name “uitulus” in a high sacred style. Thus, the thematic contours of Indo-European texts containing ethnogonic myths about the origin of peoples are revealed. The boundaries between cultures are erased, and the Indo-European prototext comes to the fore, giving impetus to the genesis of ethnonyms, the naming of totems, as well as the names of their own tribal leaders. In the end, we can conclude that the sacred names of young dairy animals are represented in the Lusitanian language. In the rite of sacrifice, the scale of high style is attested. The name “Italia” refers precisely to the solemn sacred layer of vocabulary, but already acts as the implicit name of a Latin prayer to the god Mars. The practice of giving names incorporated rules, which vary from tradition to tradition. Attention is drawn to the special nature of ethnogonic texts that shed light on the origin of peoples. Cultural boundaries can be the indicator that generates recognizable patterns that migrate from culture to culture

On one approach to the detection of infrasonic signals of irregular natural phenomena in the instrumental observations time series at the student interdisciplinary testing ground

The work is devoted to the analysis of time series and the problem of processing signals obtained as a result of the design approach implementation during the organization of instrumental observations of irregular natural phenomena at the student interdisciplinary testing ground. The objective of the work is to study the methods of processing noisy signals obtained as a result of monitoring the infrasonic environment, which make it possible to automate the search for fragments of the time series generated by irregular natural phenomena. At the beginning of the work, a brief explanation of the essence of the measuring scientific experiment carried out within the framework of the project approach used in the additional education of students and schoolchildren shall be given. The following is a review of publications describing various approaches to the analysis of nonstationary time series obtained in the process of instrumental observations. As the main method of time series analysis, it is proposed to use the algorithm for calculating the fractal dimension of the time series, proposed by T. Higuchi [1]. During studying of the time series of infrasonic signals, a number of regularities were discovered that contribute to the development of an original procedure for processing and transforming the signal under study, which makes it possible to determine the time intervals of fragments of the time series corresponding to the signals of the desired natural phenomena. The essence of the proposed approach lies in the preliminary preparation of the time series by processing the data with a simple normalized difference filter, previously smoothed by performing the coenvolution (convolution) operation with a Gaussian kernel; determining the step of segmenting the normalized time series, calculating fractal dimensions and averaged amplitudes for each of the segments of the time series and obtaining on their basis vectors of changes in dimensions and amplitudes with their subsequent element-wise multiplication. It is shown that the maximum values of the components of the resulting vector are indicators of timestamps for the location of the desired signals.

Знали ли древние греки натуральный обертоновый ряд?

Music theory, which developed in the course of a single musical-mathematical-astronomical synthesis, does not give a direct answer to the question posed – "did the ancient Greeks know the natural overtone series" as a reasonable system. Nevertheless, the musical theory in the preserved sources-original works, their fragments, compilations – came quite close to understanding of the existening of the phenomenon much later called "natural overtone series". The article attempts to find a correspondence between individual mathematically calculated intervals, the main system-forming generic tetrachordal structures (diaton, chroma, enharmony) and segments of the natural overtone series as evidence of the unity of the scientific and empirical (auditory) approach to achieving the best sound of Music, universal Harmony. The article is a revised and expanded version of the Lecture for students and teachers of conservatories "Musical acoustics in the works of ancient scientists" (Novosibirsk, 2009).

A printed-circuit heat exchanger consideration by exploiting an Al2O3-water nanofluid: Effect of the nanoparticles interfacial layer on heat transfer

Supercritical carbon dioxide (S-CO2) Brayton cycle is an encouraging power conversion technology pertaining to waste heat recovery applications, because of the high compactness and efficiency it presents. A key technological challenge for the commercialization of this technology is the improvement of the cooling process of these cycles. In this study, an analytical investigation of a printed-circuit heat exchanger (PCHE) used as precooler for S-CO2 Brayton cycles and employing an Al2O3-water nanofluid is presented. In particular, the heat exchanger is modeled as segments in series to investigate the nanofluid impact on the PCHE’s thermal-hydraulic performance. Regarding the nanoparticles consideration, the selected theoretical model for the estimation of the thermal conductivity takes into account the radius of the nanoparticles and the nanolayer thickness which is formed around it. In brief, the maximum used nanoparticle volume fraction of 5% results in an improvement of 75% for the heat transfer coefficient leading, in turn, to a reduction of 1% for the heat exchanger length and a pressure drop increase of 8%. Finally, the increase of nanoparticle radius results in a reduced effective thermal conductivity, while the nanolayer thickness of 2 nm showed an improved heat transfer coefficient by 43% compared to the minimum nanolayer thickness of 0.5 nm.

Infinite plate loaded with normal force moving along a complex path

Introduction. A technique of solving the problem on an infinite plate lying on an elastic base and periodically loaded with a force that moves along an arbitrary closed trajectory and according to an arbitrary law; is considered. Materials and Methods. An original method for solving problems on the elasticity theory for plates loaded with a force moving arbitrarily along a closed trajectory of arbitrary shape is considered. The problem on an infinite plate lying on an elastic foundation is investigated. The plate is loaded with a normal force moving at a variable speed. The load is decomposed into a Fourier series on a time interval whose length is equal to the time of its passage along the trajectory. The solution to this problem is realized through a superposition of solutions to the problems corresponding to the load defined by the summands of the specified Fourier series. The final problem solution is presented in the form of a segment of the Fourier series, each summand of which corresponds to the solution to the problem on the action on an infinite plate of the load distributed along a closed trajectory of the force motion. The fundamental solution to the vibration equation of an infinite plate lying on an elastic foundation is used to construct these solutions. Results. A solution to the problem of an infinite plane, along which a concentrated force moves at a variable speed, is presented. A smooth closed curve consisting of arcs of circles was considered as a trajectory. The behavior of displacements and stresses near the moving force is investigated; and the process of the elastic wave energy propagation is also studied. For this purpose, a change in the Umov-Poynting vector is considered. Discussion and Conclusions. The results obtained can be used in calculations for road design. The study of the propagation of the energy of elastic waves from moving vehicles will provide the assessment of the impact of these waves on buildings located near the road. Analysis of the behavior of displacements and stresses near the moving force will allow assessing the wear of the road surface.

Analysis for a solar stripper design for carbon capture under transient conditions

This paper presents an advanced thermodynamic analysis to design a solar stripper (So-St) field to replace the conventional desorption unit in a post-combustion carbon capture (PCC) plant. By eliminating the large, complex, and costly stripper, a solar collector field (SCF) consisting of a number of So-St arrays is sized to directly release the CO2 gas from the rich solvent under transient conditions. In this study, a design protocol has been developed to address the key design challenges for the evolving two-phase flow in the solar receiver tube analysing the instantaneous flow regime, pressure drop, and vapour molar fraction (VMF) to enhance the heat transfer. This design protocol optimizes the physical properties of the So-St components and eventually leads to the whole So-St field sizing based on the nominal capture capacity. A case-study is demonstrated to capture 1.5M tonneCO2/y from a representative 660 MWe coal-fired power plant in Sydney/Australia. It is found that 22 rich solvent loops that each consists of an array of 6 parallel So-St modules, where each module consists of 6 segments in series is needed. The length/diameter of these So-St segments/modules are optimized for this case-study, and the design procedures are clarified and simplified which can be easily applied for other case-studies. Techno-economic validation of this novel So-St technology is an essential step-forward to fully solarize and autonomies carbon capture industry.

Convergence of U-processes in H\xf6lder spaces with application to robust detection of a changed segment

To detect a changed segment (so called epidemic changes) in a time series, variants of the CUSUM statistic are frequently used. However, they are sensitive to outliers in the data and do not perform well for heavy tailed data, especially when short segments get a high weight in the test statistic. We will present a robust test statistic for epidemic changes based on the Wilcoxon statistic. To study their asymptotic behavior, we prove functional limit theorems for U-processes in Hölder spaces. We also study the finite sample behavior via simulations and apply the statistic to a real data example.

Planar locomotion of earthworm-like metameric robots

The goal of this research is to develop a generic earthworm-like locomotion robot model consisting of a large number of segments in series and based on which to systematically investigate the generation of planar locomotion gaits and their correlation with a robot’s locomotion performance. The investigation advances the state-of-the-art by addressing some fundamental but largely unaddressed issues in the field. These issues include (a) how to extract the main shape and deformation characteristics of the earthworm’s body and build a generic model, (b) how to coordinate the deformations of different segments such that steady-state planar locomotion can be achieved, and (c) how different locomotion gaits would qualitatively and quantitatively affect the robot’s locomotion performance, and how to evaluate them. Learning from earthworms’ unique morphology characteristics, a generic kinematic model of earthworm-like metameric locomotion robots is developed. Left/right-contracted segments are introduced into the model to achieve planar locomotion. Then, this paper proposes a gait-generation algorithm by mimicking the earthworm’s retrograde peristalsis wave, with which all admissible locomotion gaits can be constructed. We discover that when controlled by different gaits, the robot would exhibit four qualitatively different locomotion modes, namely, rectilinear, sidewinding, circular, and cycloid locomotion. For each mode, kinematic indexes are defined and examined to characterize their locomotion performances. For verification, a proof-of-concept robot hardware is designed and prototyped. Experiments reveal that with the proposed robot model and the employed gait controls, locomotion of different modes can be effectively achieved, and they agree well with the theoretical predictions.

Optimized Segmentation-Adaptive-Based Testing of the Wavelet Co-movement Analysis: the Case of US and G8 Countries

The paper deals with the identification and the description of the co-movement between the US and G8 countries with regard to the impact of the structural change, i.e. the financial crisis in 2008. For the identification of the co-movement, we use an optimized segmentation-adaptive-based approach (SAB) of significance testing of the power wavelet cross-spectrum. The SAB testing is based on the standard testing for the power wavelet cross-spectrum adapted for the case if the data have several levels of volatility during the time evolution, i.e. the data can be split into several segments with different volatility. The number of segments is set by the heteroscedasticity test and the test for comparing variances in the segments of the time series. The SAB testing allows us to identify significant co-movement with respect to the local variance, which can reveal additional significant co-movement areas. We apply this approach to the monthly data of industrial production index for G8 countries in 1993–2017.

Application of a Volterra quadratic polynomial to modeling elements of heat engineering devices

This paper considers integral models built to describe dynamic processes in a 135 MW power unit condenser. For this purpose, we use a quadratic segment of the Volterra integral power series. The first set of models was built with a perturbation of the cooling water flow, and the second one with a perturbation of the steam flow. For all sets of models, changes in pressure and temperature in the condenser, as well as temperature changes in LHP-1, were considered as a response to perturbation. For models built with perturbation of the cooling water flow velocity, we considered an extreme problem of finding optimal amplitudes of the input perturbations. The results of calculations proved to be sufficiently accurate.

Nanomechanics of single layer hybrid boron nitride–carbon nanosheets: A molecular dynamics study

The article presents an investigation on the mechanics of single layer boron nitride–carbon (BN–C) nanosheets using molecular dynamics simulations. The effective Young’s modulus of the BN–C nanosheets with varying BN concentration is first obtained by a multiscale method. The mechanics of BN–C nanosheets, with BN and graphene segments in series and parallel arrangement are then investigated. The studies showed that the BN–C nanosheet with parallel arrangement exhibits slightly improved mechanical resistance than the BN–C nanosheet with series arrangement. Furthermore, regardless of arrangement, it was found that the BN–C nanosheet loaded in zigzag direction exhibits superior tensile characteristics. While the tensile properties of BN–C nanosheet decreases with increasing defect concentration, the rate of drop was found to be strongly sensitive to the defect location. The studies also revealed that the weakening of BN–C nanosheet with defects seems to be less pronounced at elevated temperatures. The investigations on the mechanics of BN–C nanosheet conducted in this study could assist in the design of efficient nanoelectromechanical devices, nanoscale devices, and nanocomposites.

A Riemann-Type Theorem for Segmentally Alternating Series

We show that given any divergent series $$\,\sum a_n\,$$ with positive terms converging to 0 and any interval $$\,[\alpha ,\,\beta ]\subset \overline{\mathbb R}$$ , there are continuum many segmentally alternating sign distributions $$\,(\epsilon _n)\,$$ such that the set of accumulation points of the sequence of the partial sums of the series $$\,\sum \epsilon _na_n\,$$ is exactly the interval $$\,[\alpha ,\,\beta ]$$ . We add some remarks on various segmentations of series with mixed sign terms in order to strengthen a sufficient criterion for convergence of such series.