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One of the basic skills of a dancer is the ability to keep the body balance (aplomb) while performing various dance figures. These movements are often performed with limited vision control due to dynamic motion or environmental conditions. Our aim was to verify whether the exercises with eyes closed of the ballet school students would reduce postural sway whilst improving the body balance. The training without visual feedback forces the body to rely more on information from the proprioceptive system about the alignment and motion of body parts in relation to each other and the external environment. In a group of thirteen female students of Comprehensive Ballet School, a significant reduction in postural sway was already found after three weeks of the nine-week training. This phenomenon occurred only during quiet standing with eyes closed. The use of stabilographic testing can be recommended as an objective evaluation of the aplomb level in ballet dancers. At the same time, this research showed that the introduction of ballet exercises with eyes closed improved postural stability without compromising stability with eyes open. Therefore, it can be assumed that such exercises do not harm but rather may be beneficial for the development of aplomb. [ABSTRACT FROM AUTHOR]

Rock and soil masses in geotechnical engineering projects, such as tunnels, mines and slopes, undergo relative motion, exhibiting mechanical characteristics of solid–fluid transition under critical conditions. This work analyzes the characteristics of the solid–fluid transition interface and the mode of load transfer through biaxial compression particle flow photoelastic experiments on granular materials. The study documents that this interface forms an arch shape, marked by a force chain arch. The granular material exhibits two distinct states depending on its position: below the arch, the granular material is in a solid–fluid transitional state, with bearing capacity reduced, while above the arch, it is in a stable solid state, capable of bearing the overlying rock layer's load. The presence of the force chain arch alters the direction of the originally downward-transferring load, redirecting it along the trajectory of the arch. Analysis of the force and stability of the force chain arch revealed that the arch shape parameters and boundary loads control the instability of the arch. Changes in the overlying and lateral loads lead to different types of instability of the force chain arch. The findings of the study are crucial for underground engineering construction and for the prevention of geological disasters related to granular material. [ABSTRACT FROM AUTHOR]

Copyright of Polish Statistician / Wiadomości Statystyczne is the property of State Treasury - Statistics Poland and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper considers the comparative analysis of the physical and mathematical methods of the optimal operation of aviation objects' automatic control systems, which is an urgent scientific and technical task. The paper also represents the corresponding stability criteria, depending on the operating conditions, and the influence of external factors that allows ensuring the automatic control systems' reliable operation not only in normal circumstances, but also in the presence of probable disagreements. The scientific novelty of the research lies in developing new stability criteria by means of synthesising the influence of different factors and also the ability to ensure optimal functioning of the automatic control systems. Corresponding mathematical and computer models have been developed. The use of these models allows to determine the optimal stability criteria for control systems with parameters of a different physical nature and ensure reliable operation of electromechanical systems for general and special applications based on the current analysis. The research results are illustrated by corresponding mathematical models, engineering calculations and modelling of the optimal control limits depending on the influence of various factors. The simulation results coincide with the theoretical calculations, which indicates the consistency between the microprocessor-based and software of automatic control systems. [ABSTRACT FROM AUTHOR]

Studying the spatial response of a single-axis magnetometer could be the key parameter to optimize the ultimate performances of magnetic heads of detection. Indeed, the problem of non-orthogonality, misalignment, and 3D spatial response could be improved based on the knowledge of the 3D sensor spatial response. In that way, we have investigated the latter for our giant magneto-impedance (GMI) magnetometer, as a far-field pattern, by using a three-axis Helmholtz coil system. Firstly, we calibrate our device and secondly, we apply a specific 3D magnetic field to obtain this pattern. The latter helps to observe the directional or angular dependence of the sensor sensitivity versus the applied magnetic field, as we exemplified. The results confirm the excellent directivity of our off-diagonal GMI magnetometer. The evaluation of the associated error compared to an ideal vector magnetometer is also given and discussed. [ABSTRACT FROM AUTHOR]

In this paper, stability analysis and stabilization control of discrete-time impulsive switched time-delay systems with all unstable subsystems are discussed. By utilizing a switching time-varying Lyapunov-Krasovskii functional and the mode-dependent interval dwell-time switching rule, we derive some more general stability theorems for the considered time-delay system with all subsystems being unstable. Moreover, we design a time-varying state feedback controller to ensure the stabilization of the resulting closed-loop system. Eventually, the theoretical findings are demonstrated utilizing numerical examples. [ABSTRACT FROM AUTHOR]

The article describes the development stages of an adequate regulatory structure for the slope stability in open pit mines. Some supplementary factors that have influence on stability of slopes in open pit mines in the gravity–tectonic stress field are discussed. The main trends of research of pitwall rock mass in operating surface mines are presented, and the necessity of determining the tectonic stresses in pitwall rock mass and taking into account their impact on slope stability is emphasized. The algorithm is developed for justifying slope parameters for open pit mines under tectonic stresses, the drilling-and-blasting principles are formulated for the operation in pitwall rock mass, and the methods are proposed to mitigate the blasting-induced impact on adjacent rocks. [ABSTRACT FROM AUTHOR]

Time scales in Celestial Mechanics and Astrodynamics vary considerably, from a few hours for the motion of Earth's artificial satellites to millions of years for planetary dynamics. Hence, the time scales on which one needs to investigate the stability of celestial objects are different. Therefore, the methods of study are themselves different and might lead to specific definitions of stability, either in the sense of bounds on the initial conditions or rather in the sense of confinement in a given region of the phase space. In this work we concentrate on three different methods: perturbation theory, Nekhoroshev's theorem, KAM theory. All theories are constructive in the sense that they provide explicit algorithms to give estimates on the parameters of the system and on the stability time. Perturbation theory gives results on finite time scales, Nekhoroshev's theorem provides stability results on exponentially long times, KAM theory ensures the confinement between invariant tori in low-dimensional systems. We recall the basic ingredients of each theory, starting with KAM theory, then presenting Nekhoroshev's theorem and finally introducing perturbation theory. We provide examples of stability results for some objects of the Solar system. Precisely, we consider the stability of the rotational motion of the Moon (or other planetary satellites) within the spin-orbit model by means of KAM theory, we analyze the stability of asteroids, also in the triangular equilibrium Lagrangian points, using Nekhoroshev's theorem, we study the Earth's satellite dynamics through perturbation theory. [ABSTRACT FROM AUTHOR]

In this study, an accurate tool is provided for the evaluation of the effect of joint motion effect on gait stability. This quantitative gait evaluation method relies exclusively on the analysis of data acquired using acceleration sensors. First, the acceleration signal of lower limb motion is collected dynamically in real-time through the acceleration sensor. Second, an algorithm based on improved dynamic time warping (DTW) is proposed and used to calculate the gait stability index of the lower limbs. Finally, the effects of different joint braces on gait stability are analyzed. The experimental results show that the joint brace at the ankle and the knee reduces the range of motions of both ankle and knee joints, and a certain impact is exerted on the gait stability. In comparison to the ankle joint brace, the knee joint brace inflicts increased disturbance on the gait stability. Compared to the joint motion of the braced side, which showed a large deviation, the joint motion of the unbraced side was more similar to that of the normal walking process. In this paper, the quantitative evaluation algorithm based on DTW makes the results more intuitive and has potential application value in the evaluation of lower limb dysfunction, clinical training and rehabilitation. [ABSTRACT FROM AUTHOR]

We study the behavior of a collapsible tube conveying a fluid subject to external pressure that could occur in many physiological applications. The method of rotating spines is developed to enable an automatic mesh adaptation when the tube is deformed largely. We examine bifurcation diagrams when the tube is collapsed under a pressure driven condition and reveal that multiple solutions exist for a range of the Reynolds number. The stability characteristic of the system is discovered by determining stability of these solutions by the eigenvalue method for the first time, which is validated by solving a time-dependent problem of the system. [ABSTRACT FROM AUTHOR]

Gradiently denitrated gun propellant (GDGP) prepared by a "gradient denitration" strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant. Currently, the preparation of GDGP employed a tedious two-step method involving organic solvents, which hinders the large-scale preparation of GDGP. In this paper, GDGP was successfully prepared via a novelty and environmentally friendly one-step method. The obtained samples were characterized by FT-IR, Raman, SEM and XPS. The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant, with a well-preserved nitrocellulose structure. The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance, as confirmed by oxygen bomb and closed bomb test. At the same time, the effects of different solvents on the component loss of propellant were compared. The result showed that water caused the least component loss. Finally, the stability of GDGP was confirmed by methyl-violet test. This work not only provided environmentally friendly, simple and economic preparation of GDGP, but also confirmed the stability of GDGP prepared by this method. [ABSTRACT FROM AUTHOR]

The analysis of the post-buckling behavior of elastic structures still needs the resolution of a body of non-linear differential equations according to equilibrium equations. Also, the yielding and buckling factors are important in the procedure of designing members under forces such as axial or conjoint axial force and bending moment. In such a way that if the length of the member is too long or the member is thin, before the yielding, buckling will occur in the member, and it is necessary to check and control the member for possible buckling. The present work deals with the stability analysis of elastic columns with variable cross-sections under concentrated end load and proposes a simplified approach to the evaluation of the critical buckling force of columns according to the assumptions of the Elastica theory. In this paper, the power series are used to simplify the equations. The numerical issues of the critical buckling force are presented for prismatic and non-prismatic columns subjected to end force, and the effectiveness of this approach is verified for buckling analysis of tapered columns, and the rate of accuracy is assessed. The elastic buckling force of elastic structures shows that the introduced model is computationally extremely efficient with the details presented in general. This paper should be a basic reference to compare the results with other research. [ABSTRACT FROM AUTHOR]

The article shows natural and architectural analogies in which triangular and arched arches are the most stable. A new design of a drainage pipe with a cross section in the form of a Reulot triangle with an angular arch, related to cycloidal structures and increased stability, has been developed. Based on model studies, it was revealed that the arches in the form of half an astroid are the most stable, in this regard, a new design of a drainage pipe with a vault in the form of intersecting hyperbolas has been developed, which practically corresponds to half an astroid. [ABSTRACT FROM AUTHOR]

Living systems may be defined as systems able to organize new, biology-specific, laws of physics and modify their parameters for specific tasks. Examples include the force-length muscle dependence mediated by the stretch reflex, and the control of movements with modification of the spatial referent coordinates for salient performance variables. Low-dimensional sets of referent coordinates at a task level are transformed to higher-dimensional sets at lower hierarchical levels in a way that ensures stability of performance. Stability of actions can be controlled independently of the actions (e.g., anticipatory synergy adjustments). Unintentional actions reflect relaxation processes leading to drifts of corresponding referent coordinates in the absence of changes in external load. Implications of this general framework for movement disorders, motor development, motor skill acquisition, and even philosophy are discussed. [ABSTRACT FROM AUTHOR]

• Folding stability mechanics of a bistable composite tape-spring towards its full tape-length range is revealed. • Novel features in terms of critical transitional length and stable folded angle are observed and identified. • Theoretical criteria for folding stability are determined from the established strain energy model. A bistable composite tape-spring (CTS) structure is stable in both extended and coiled configurations, which can be fully coiled or folded. Its bistable coiling feature has been employed in a Roll-Out Solar Array and successfully deployed in space; its foldable characteristics is analogous to a flexible mechanical hinge, showing great potential to be applied in an aircraft landing gear. Both the structural coiling and folding mechanics are dependent on tape geometry; whilst the correlated scale effect has not been investigated, which significantly constrains its foldable mechanical hinge designs and smart driving analysis in order to further reduce weight and complexity for conventional mechanical hinges. Here, we studied the folding stability mechanics of the CTS structure towards its full tape-length range, where novel stress and shape transitional mechanisms are revealed. This is achieved by investigating the quasi-static folding process of the CTS, where new stable shape features in terms of critical transitional length and stable folded angle are observed and identified through experimental observations, finite element model, as well as theoretical analysis. Theoretical criteria were then determined from the strain energy analysis in comparison to the predefined folded tape shape features. The folding stability mechanisms towards its full tape-length range were proposed in order to facilitate customized flexible hinge design and in-situ smart driving analysis in order to replace conventional mechanical hinges. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to investigate the aftereffect of a six-week virtual reality environment training on dynamic and static postural stability in athletes participating in random intermittent dynamic type sports. The pretest and posttest study designs were chosen to conduct this study. Twenty-four male athletes were selected for the study. Participants participated in a six-week virtual reality environment training program three times a week for a session of forty-five minutes. The virtual reality environment was created using CAREN's integrated virtual reality system with Motek's D-flow application. The postural stability was assessed using a stadiometer. Assessments were performed before and after six weeks of training. A paired sample t-test was used to determine differences between pretest and posttest outcome measures. The improvement can be seen as an effect of virtual reality environment training intervention. Statistically significant differences were observed between pretest and posttest for dynamic and static anteroposterior and mediolateral postural stability at 20 and 40 levels of difficulty. The virtual reality environment training helps to improve performance by assessing and optimizing the training load in the process of improving the performance of athletes participating in random intermittent dynamic type sports. [ABSTRACT FROM AUTHOR]

The influence of a magnetic field on the stability of a shaped charge jet is experimentally investigated at standoffs of 490, 650 and 800 mm. The experimental results without and with the magnetic field are compared in terms of the shaped charge jet form, stability and penetration ability. A theoretical model based on one-dimension fluid dynamics is then developed to assess the depth of penetration of the shaped charge at those three standoffs and magnetic conditions. The results show that the penetration capability can be enhanced in more than 70% by the magnetic field. The theoretical calculations are compared with the experimental results with reasonably good correlation. In addition, the parameters introduced in the theory are discussed together with the experiments at three standoffs studied. [ABSTRACT FROM AUTHOR]

The study aimed to (1) compare postural stability between sitting and standing in healthy individuals and (2) define center-of-pressure (COP) measures during sitting that could also explain standing stability. Fourteen healthy individuals randomly maintained (1) two short-sitting positions with eyes open or closed, with or without hand support, and (2) one standing position with eyes open with both upper limbs resting alongside the body. Thirty-six COP measures based on time and frequency series were computed. Greater COP displacement and velocity along with lower frequency measures were found for almost all directional components during standing compared with both sitting positions. The velocity, 95% confidence ellipse area, and centroidal frequency were found to be correlated between unsupported sitting and standing. Despite evidenced differences between sitting and standing, similarities in postural control were highlighted when sitting stability was the most challenging. These findings support further investigation between dynamic sitting and standing balance. [ABSTRACT FROM AUTHOR]

The authors conducted two experiments that served as a test bed for applying the recently developed uncontrolled manifold (UCM) approach to rhythmic motor coordination, which has been extensively investigated from a coordination dynamics perspective. The results of two experiments, one investigating within person and one investigating between-persons rhythmic movement coordination, identified synergistic behaviors in both of those types of coordination. Stronger synergies were identified for in-phase than antiphase coordination, at the endpoints of the movement cycles compared with the midpoints, for movement frequencies closer to the intrinsic frequency of the coordinated limbs, and for within-person coordination. Frequency detuning did not weaken the strength of interlimb rhythmic coordination synergies. The results suggest the synergistic behavior captured by the UCM analysis may be identifiable with the strength of coupling between the coordinated limbs. The UCM analysis appears to distinguish coordination parameters that affect coupling strength from parameters that weaken coordination attractors. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate differences between the occlusal contacts of edentulous patients with mandibular implant-supported hybrid dentures opposing maxillary complete dentures and those of patients with conventional maxillary and mandibular complete dentures. Six parameters related to occlusion were measured in the 2 groups (n = 40 for each group) using pressure-sensitive film. The mean values generated by each test group for each parameter were compared using a t test. Pearson's correlation coefficients between occlusal force, age, and time in function were examined. Occlusal force and area in the implant denture wearers were larger than those in the conventional denture wearers. No significant difference was seen in occlusal force balance between the left and right sides. The center of occlusal load in the implant denture wearers was more anterior. The maxillary denture may become more unstable in implant denture wearers. It is suggested that the stability and retention of a maxillary denture be checked and the occlusion be adjusted more frequently in the hybrid denture wearer than in the conventional denture wearer. [ABSTRACT FROM AUTHOR]

Through two-step emulsification method, the multiple emulsions were firstly prepared with paraffin as internal oil phase, Tween-80 as hydrophilic emulsifier and gelatin as thickener, and then were used to encapsulate Vitamin C. The effect of various parameters on the stability of multiple emulsions was investigated by determining the volume changes after centrifugation and the encapsulation changes of Vitamin C during two weeks. These factors included the species and amount of emulsifier, the dosage ratio of two phases, emulsion temperature, homogenization speed and the dosage of polymer, three of which were most influential. The optimal formula and preparation process were obtained through orthogonal experiment, that was, Tween-80 and P135 as foreign and internal emulsifiers, respectively, the mass ratio of Tween-80 was 2%, the dosage of external phase was 1.0, and the emulsification temperature was 45 °C, homogeneous speed was 2000 r/min, gelatin dosage was 0.5%. Under this condition, the relative volume ratio of multiple emulsions was 0.966 4, the performance was stable, and the encapsulation rate of Vitamin C could reach 98%, and the multiple emulsions had a satisfactory package stability. [ABSTRACT FROM AUTHOR]

Since the half-shaft is the main flexible part of the automotive driveline, the torsional dynamics of the simplified driveline considering the cubic nonlinearity of the half-shaft is discussed in the paper. The approximate solutions of the torsional shock response and the resonance response of the driveline are derived using the method of multiple scales. The stability and bifurcation condition of the responses are judged based on the Routh–Hurwitz criterion and the bifurcation theory, respectively. It is shown that the negative cubic nonlinear stiffness is propitious to suppress the torsional shock of the driveline while the positive is on the contrary. Meanwhile, the ability of the suppression of the torsional shock can be improved with the decrease in the linear stiffness. The resonance curve of the driveline may lose its stability when the value of the cubic nonlinear stiffness reaches the threshold. By properly designing the negative cubic nonlinear stiffness of the half-shaft, the instability of the resonance can be suppressed and the ability of the suppression of the torsional shock can also be improved. [ABSTRACT FROM AUTHOR]

• Initial Voc drop of encapsulated PCDTBT:PC 70 BM solar cells with PEDOT:PSS HTL. • Replacing PEDOTS:PSS by MoO 3 as HTL prevents this burn-in degradation. • Photo-degradation during first sun-hour, independent of sunlight concentration. • Decay of performance with exposure dose independent of sunlight concentration. • Concentrated sunlight can be used for accelerated stability assessment of devices. Encapsulated organic solar cells often show a burn-in behaviour under illumination. This burn-in manifests itself as a rapid performance loss followed by a much slower progression of the degradation. Here we investigate the burn-in for PCDTBT:PC 70 BM solar cells under a wide range of illumination intensities. We find that increasing the sunlight concentration from 1 Sun to up to 100 Suns does not change the degradation behaviour, i.e. the dependence of all principal photovoltaic parameters on the dose of solar exposure (in Sun hours). This suggests that the degradation mechanisms under solar concentration (≤100 Suns) are the same as those observed under 1 Sun. This result makes it possible to use concentrated sunlight for accelerated stability assessment of these devices. We also find that devices with PEDOT:PSS as hole transport material show a rapid drop in open-circuit voltage of around 100 mV during the first Sun hour of light exposure. By replacing PEDOT:PSS with MoO 3 this initial process can be prevented and only the much slower part of the photo-degradation takes place. [ABSTRACT FROM AUTHOR]

Highlights • The buckling behavior of the confined FGM arch under external pressure is different from that of the unconfined FGM arch. • The confinement effect results in significant development on the critical buckling pressure of the FGM arch. • The FGM arch shows different mechanical behavior from the homogeneous arch due to non-symmetrical material property. • The analytical buckling pressure of the confined FGM arch is obtained and verified successfully by the numerical result. Abstract This paper investigates the buckling of confined thin-walled functionally graded material (FGM) arch subjected to external pressure. The confined FGM arch buckles in a single-lobe deformation expressed by an admissible radial displacement function. The critical buckling pressure of the confined FGM arch is obtained analytically by establishing the nonlinear equilibrium equations based on the classical thin-walled arch theory. Subsequently, a two-dimensional (2D) finite element model (FEM) is established to trace the pre- and post-buckling equilibrium paths. Geometric nonlinearities are introduced since large displacement and rotation occur during the whole deformation of the FGM arch. The numerical results show very close agreement with the present analytical solutions in terms of the hoop force through the FGM arch span, the critical buckling pressure, and the pressure-displacement equilibrium paths. Furthermore, the present predictions are compared successfully with other closed-form expressions for the confined homogeneous arch. Finally, the effect of volume fraction exponent on the buckling pressure, the hoop force and bending moment through the arch span is examined and discussed to further understand the buckling behavior of the confined FGM arch. [ABSTRACT FROM AUTHOR]

Abstract Competitive behavior, like predation, widely exists in the world which has influences on the dynamics of ecosystems. Though a good knowledge for the patten formation and selection of predator–prey models with diffusion is known in the literature, little is known for that of a diffused competition model. As a result, a competition model with saturation effect and self- and cross-diffusion is proposed and analyzed in this paper. Firstly, by making use of nullcline analysis, we derive the condition of existence and stability of positive equilibrium and prove global stability. Then using the linear stability analysis, the Turing bifurcation critical value and the condition of the occurrence of Turing pattern are obtained when control parameter is selected. Finally, we deduce the amplitude equations around the Turing bifurcation point by using the standard multiple scale analysis. Meanwhile, a series of numerical simulations are given to expand our theoretical analysis. This work shows that cross-diffusion plays a key role in the formation of spatial patterns for competitive model with saturation effect. [ABSTRACT FROM AUTHOR]

Brayton–Moser's mixed potential theory has been used to analyse the large disturbance stability of DC microgrid with constant power load (CPL), such as current-mode controlled BUCK/BOOST converter with CPL or DC system with multi-stage LC filters. However, the stability analysis of other topology of DC–DC converter or multiple converters worked under droop control is rarely involved. Based on this issue, this paper first establishes the mixed potential model of a single bidirectional BUCK/BOOST converter with CPL. Then, the paper gives the method for establishing the mixed potential model of a droop-controlled DC microgrid with multiple bidirectional BUCK/BOOST converters and CPL. Afterwards, the stability criterion of the analytic form of the system under large disturbance is obtained, which shows that the parameters such as system parameters, control parameters, droop coefficients, and CPL power value have the effects on the system's large signal stability. This paper gives and discusses the relationship between system parameters and stability. Thus, instead of calculating and simulating repeatedly, the stability criterion can judge and ensure the stability of the system under large disturbance in the design process. Simulation results demonstrate the correctness of the simple and easily implemented stability criterion. [ABSTRACT FROM AUTHOR]

The LLCL filter is widely used in grid-tied inverter systems due to its small size, low cost and good attenuation for high-frequency harmonics. However, the LLCL filter resonance phenomenon and the wide range of impedance may compromise the system stability. In order to solve these problems, a coordination control strategy for LLCL-filter-based grid-tied inverter with indirect sliding mode power control and virtual impedance was presented. The LLCL filter design parameter has been carefully adjusted to ensure the system stable operation under a wide range of grid impedance variations. Comparing with the traditional proportional integral control system through simulation experiment, the output current harmonics of grid-tied inverter are analysed. The proposed strategy is feasible with good control accuracy and tracking performance. [ABSTRACT FROM AUTHOR]

This paper describes a unified static/dynamic entropy generator based on a 512-b common entropy source (ES) array fabricated in 14-nm tri-gate CMOS with reconfigurable and adaptive post-processing circuits implemented on Arria 10 FPGA, targeted for flexible and secure privacy preserving mutual authentication on compact trusted mote platforms at the edge of internet of things. Several conditioning techniques that include temporal majority voting (TMV)-assisted ES array segregation with integrated bias tracking, three-way in-line self-calibration for tolerance to process–voltage–temperature variation, tri-level hierarchical Von Neumann (VN) extraction to maximize entropy harvesting, soft-dark bit masking for improving physically unclonable function (PUF) stability, and selective stress hardening to co-optimize the ES array for static-dynamic entropy with bias aware device aging enable simultaneous PUF and true random number generator (TRNG) operation with 1.48 and 0.56 Gb/s throughput, respectively, measured at 650 mV, 70 °C. The all-digital design with a compact layout footprint of 2114 $\mu \text{m}^{2}$ facilitates seamless integration in area constrained system-on-chips while achieving: 1) 25% area savings over conventional separate PUF and TRNG implementations; 2) cryptographic quality TRNG stream that passes all NIST randomness tests with 0.38 average p-value; 3) $1.6\times $ higher extractor performance at $9\times $ lower area with 750-gate hierarchical VN circuit over conventional light-weight entropy extractors; 4) 0.9996/0.99997 static/dynamic Shannon entropy indicating unbiased PUF/TRNG streams; 5) ultra-low energy consumption of 2.5 and 0.46 pJ/bit measured at 650 mV, 70 °C in TRNG and PUF modes; 6) 40% higher TRNG throughput with three-way self-calibration featuring coarse-grain column swap, fine-grain incremental ES substitution, and residual entropy recycling; 7) resistance to power injection attacks as measured by 64% higher performance over un-calibrated design in the presence 200-mV supply noise; 8) 2.8% PUF bit-error measured at 0.55–0.75 V, 25 °C–110 °C with 15-way TMV and soft dark-bit masking over a window of 100 cycles; 9) $14.8\times $ inter and intra-PUF hamming distance separation; and 10) 56% reduction in discarded ES cells with selective stress hardening to opportunistically reinforce/nullify pre-existing bias in PUF/TRNG candidate cells. To our knowledge, this is the first reported unified PUF-TRNG implementation enabling simultaneous generation of high-entropy chip-ID and encryption keys in real time. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this study is to provide an exhaustive review of the literature on the vibration and buckling of functionally graded materials (FGMs), functionally graded conical shells (FGCSs), functionally graded layered conical shells (FGLCSs), and functionally graded sandwich-conical shells (FGSCSs). The methodological solutions for various problems encountered in pure FGCSs and FGSCSs in the design, for example, linear and non-linear (NL) vibration and stability under various loads and the influences of the different environment are presented. The examples of FGM structures included in the review cover a wide range of applications in nuclear, space and marine engineering, electronics and biomedical fields. [ABSTRACT FROM AUTHOR]

Abstract Although the stability of the sandwich structures under in-plane excitation has been reported, few of them focus on the functionally graded materials (FGM) sandwich doubly curved shallow shells. Moreover, for the study of static bifurcation, stability and dynamic stability analysis, it is common to ignore the effect of thickness tension or compression. The purpose of this paper is to explore the bifurcation and stability of the FGM sandwich doubly curved shallow shell which is subjected to the in-plane excitation in thermal environment. By introducing the secant function to the transverse displacement, a new displacement field based on the Reddy's third order shear deformation theory is derived. It is assumed that the material properties of sandwich doubly curved shallow shell are temperature dependent. The distribution of component materials in FGM layer obeys the rule of power law in the radial direction. Considering the geometric nonlinear, using an energy approach and the Galerkin's method, a two-degree-of-freedom non-autonomous nonlinear dynamic equation with parametric excitation is derived. The threshold of the bifurcation and the stability of the structure are investigated. The instability regions are plotted by dynamic load factor against excitation frequency in α 1 - Ω plane. [ABSTRACT FROM AUTHOR]

Flax (Linum usitatissimum L.) is a plant of industrial interest. Its fibres have traditionally been used for textile applications and more recently, for composite reinforcement. To increase fibre yields, varietal selection has been used to develop varieties having high fibre content while retaining good resistance to lodging. This selection process has led to impressively slender structures of flax compared to other herbaceous plants. The present study focuses on the mechanical stability of flax related to its specific architecture. An anatomical study of transverse sections provides information about the architecture of flax stems, including the repartition of the internal reinforcing tissues being phloem fibres and xylem. Then, by using three-point bending tests, flexural modulus is evaluated along the stem. The safety factor (SF) against buckling for the plant was estimated based on Greenhill's model, taking into account gradients in diameter, load, and elastic modulus. Although flax plants have an unusually slender structure, they are mechanically stable. The stability of the plant is ensured by a high stem flexural modulus. This originates from an external ring composed of high-performance fibres, while an inner thick porous xylem provides the plant with a high resistance to local buckling. This is useful information for breeders, demonstrating that it is possible to keep increasing fibre yield without jeopardising plant stability. Highlights • The mechanical stability of flax in relation to its slenderness is investigated. • Morphological and mechanical characteristics along a stem are explored. • Parameters influencing the mechanical stability are evaluated using a buckling model. • Flax stems have a high flexural modulus comparable with the ones of trees. • The acropetal modulus gradient does not significantly decrease the plant stability. [ABSTRACT FROM AUTHOR]

The present study explores a retaining wall with an intermediate slab. To reduce the lateral earth pressure on the wall, the substitution of part of the soil by blocks of expanded polystyrene (EPS) with high density is proposed, which could result in significant economic savings. Also, the possibility of building the wall elevation with smaller thickness (preexisting wall reinforcement) will be analyzed. To do this, the situation and optimum geometry of the EPS blocks will be studied in detail, besides a study of two scaled models, one without EPS and another with blocks with rectangular distribution. The obtained results allow us to affirm that the reduction in pressure is very significant if the blocks are arranged with the proper geometry and situation over the sliding plane but without eliminating the beneficial effect of the weight of the ground located over the slab. [ABSTRACT FROM AUTHOR]

Abstract The direct conversion of solar radiation into electricity is an abundant, clean and renewable approach for the production of energy. The organic/inorganic trihalide perovskites have shown an auspicious opportunity for the development of cost effective and efficient solar cells, owing to their unique optoelectronic characteristics. Although the developed perovskite solar cells exhibited efficiency reached to 20%, the hysteresis, device stability and toxicity of lead are serious problems hindering their commercialization. Here, we report about the partial replacement of lead ions by lanthanum ions in the crystal structure of the organic/inorganic trihalide perovskites. The photovoltaic performance of the FTO/b-TiO 2 /mp-TiO 2 /CH 3 NH 3 [La x Pb 1-x ]I 3 /NiO/Au at various contents of La ions (0 ≤ x ≤ 0.07) was evaluated. Among all developed devices, the FTO/b-TiO 2 /mp-TiO 2 /CH 3 NH 3 [La 0.07 Pb 0.93 ]I 3 /NiO/Au device exhibited the highest short-circuit current density (J sc = 19.53 mA.cm−2) and largest open-circuit voltage (V oc = 0.9 V). This device exhibited remarkable air stability with retaining 96% of the PCE, FF, V oc and J SC along four months under ambient environmental conditions. This device showed a significant reduction of the I–V hysteresis compared to un-doped device. The reason for such improvement of the photocurrent, stability and reduction of hysteresis was argued to the strong chemical bonds formed between the La ions and the nitrogen and lead atoms as confirmed by the IR spectroscopy and the increase of perovskite grains as indicated from the XRD and SEM measurements. [ABSTRACT FROM AUTHOR]

Abstract In this article, we study the stability and multiplicity of normalized standing waves for the inhomogeneous nonlinear Schrödinger equation with a harmonic potential arising in nonlinear optics. [ABSTRACT FROM AUTHOR]

Abstract Recently, El Smaily et al. (2011) proved the existence of curved fronts in a periodic shear flow, which satisfy some "conical" conditions at infinity in the whole plane R 2. In this paper, we study the stability of these curved fronts. In fact, we prove that all the curved fronts are exponentially stable provided that the initial perturbations decay exponentially with an appropriate rate in the lower cone. [ABSTRACT FROM AUTHOR]

The first example of mono‐platinum(II) complex composed of mono‐lacunary α‐Keggin‐type polyoxotungstate is described. The mono‐platinum(II)‐containing polyoxotungstate [(CH3)4N]4H[α‐PW11O39{cis‐PtII(Me2ppz)}]·5H2O (Me2ppz = N,N′‐dimethylpiperazine) (TMA‐1) was synthesized by a 1:1 stoichiometric reaction of mono‐lacunary α‐Keggin polyoxotungstate, [α‐PW11O39]7–, with cis‐PtCl2(Me2ppz) in an aqueous solution, followed by purification from water. The compound TMA‐1 was characterized by elemental analysis, thermogravimetric/differential thermal analysis (TG/DTA), and Fourier transform infrared (FTIR), ultraviolet‐visible (UV/Vis), and solution {1H, 13C, 31P, 195Pt, and 183W} nuclear magnetic resonance (NMR) spectroscopy. The characterization results indicated that a platinum(II) moiety, [cis‐Pt(Me2ppz)]2+, was coordinated to two oxygen atoms in a mono‐vacant site of [PW11O39]7– with asymmetric configuration, resulting in an overall C1 symmetry. The polyoxoanion [α‐PW11O39{cis‐PtII(Me2ppz)}]5– (1) was more stable in dimethylsulfoxide and water than the α‐Keggin‐type polyoxotungstate‐coordinated mono‐platinum(II) complex, [α‐PW11O39{cis‐Pt(NH3)2}]5–, which was also obtained by the reaction of [α‐PW11O39]7– with cis‐diamminedichloroplatinum(II) in an aqueous solution. We synthesized a tetramethylammonium salt of α‐Keggin‐type polyoxometalate‐coordinated mono‐platinum(II) complex [(CH3)4N]4H[α‐PW11O39{cis‐PtII(Me2ppz)}]·5H2O (Me2ppz = N,N′‐dimethylpiperazine) (TMA‐1), using cis‐PtCl2(Me2ppz) as the starting platinum(II) complex. The polyoxoanion 1 was more stable in dimethylsulfoxide and water than [α‐PW11O39{cis‐Pt(NH3)2}]5–. [ABSTRACT FROM AUTHOR]

Mazharimousavi and Halilsoy [S. H. Mazharimousavi and M. Halilsoy, Mod. Phys. Lett. A31, 1650192 (2016)] recently proposed wormhole solutions in f(R)-gravity that satisfy energy conditions but are unstable. We show here that stability could still be achieved for thin-shell wormholes obtained by gluing the wormholes in f(R)-gravity with the exterior Schwarzschild vacuum. Using the new geometrical constraints from thin-shell "mass" and from external "force" developed by Garcia, Lobo and Visser, we demarcate and analyze the stability regions. [ABSTRACT FROM AUTHOR]

This research report is concerned with the derivation of two evolution equations of two obliquely interacting wave packets in a two-layer fluid domain in which the lower fluid is of infinite depth. These two evolution equations are then employed to perform stability analysis of two obliquely interacting uniform wave trains. Results of the stability analysis are shown graphically. It is observed that the growth rate of instability increases as the thickness of the upper lighter fluid increases. If the angle of interaction between the two waves is acute then the growth rate of instability decreases with the increase in the angle; but the result is reversed if the angle of interaction is obtuse. Also, the growth rate of instability of one wave train increases with the increase in the amplitude of the other wave train. [ABSTRACT FROM AUTHOR]

Ball-end milling has been commonly used in the manufacturing of complex surfaces and structures. In order to improve the machining efficiency and ensure the manufacturing quality, chatter has to be avoided. The stability of cylindrical end mills has been well studied by selecting the most flexible dominant mode. This paper models the chatter stability of ball-end milling cutter with multiple modes and solves it in discrete time domain. Firstly, the multiple degree-of freedom (DOF) vibration model of the tool-workpiece system is established in modal coordinates to decouple the delay differential equations (DDEs). Then, to complete the motion equations of ball-end milling cutter, the cutting force model considering regenerative effect is built by evaluating the dynamic thickness at each cutting point along the cutting edge. Finally, the stability lobe diagram (SLD) of ball-end milling is solved by full-discretization method in discrete time domain. The cutting tests carried out on a machining center verify the prediction accuracy and observe chatter phenomenon caused by different dominant modes. [ABSTRACT FROM AUTHOR]

Abstract Fluid–structure interaction of an inverted flag, which has a free leading edge and a clamped trailing edge, has drawn attention recently because of its novel properties such as divergence stability, a low stability threshold, and large-amplitude flapping motion. In this study, the stability and flapping behaviors of dual inverted flags with finite height are investigated for a side-by-side arrangement, and their noticeable characteristics are compared to those of dual conventional flags. The critical velocity at which the inverted flags break the equilibrium of a straight configuration reduces monotonically when a gap distance between the two flags becomes smaller and an aspect ratio becomes larger, which is also predicted by our linear stability analysis using simple theoretical models of two-dimensional flags and slender flags. After bifurcation, in addition to the synchronized in-phase and out-of-phase modes commonly observed in dual conventional flags, a novel attached mode appears which is mainly observed for small gap distance and small aspect ratio. In this non-linear mode, the leading edges of the two inverted flags touch each other on a midline, and the deformed inverted flags maintain static equilibrium. In a non-linear flapping regime, a new mechanism of a mode transition from an out-of-phase mode to an in-phase mode is identified, which is allowed by the collision of the two flags flapping with large amplitude. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Systematical study of the stability of SERS enhanced response of silver grating under various physical and chemical load is presented. The study of the stability of SERS response of silver grating under various physical and chemical load is presented. • The as-prepared silver gratings provide excellent enhancement and perfect reproducibility of SERS signal. • The substrates were exposed to cyclic temperature, humidity treatments and soaked in the physiological or BSA solutions. • Obtained results indicate that the temperature or humidity treatments affect the SERS efficiency only mildly. • Under the combined humidity and temperature treatments the substrate functionality is worsened strongly. • Soaking of SERS substrate in the physiological or BSA solutions significantly reduces the SERS efficiency and reproducibility. Abstract The increased involving of Surface Enhanced Raman Spectroscopy (SERS) in the.analytical and bioanalytical field makes this technique commercially available. However, the growing range of available SERS substrates opens the question regarding the stability of SERS substrates during their storage, transportation, and utilization. In this paper, we present systematical study of the stability of SERS enhanced response of SERS-active silver grating under various physical and chemical loads. The silver coated periodical gratings provide excellent enhancement and reproducibility of SERS signal, achieved at the macroscale. The substrate load procedures include the temperature, humidity tests, and their combination. Since the utilization of SERS substrates often involves their interaction with various (bio)environments, the effects of physiological media were studied too. In all cases, the effects of the loads were determined from the changes of SERS effectivity and reproducibility. [ABSTRACT FROM AUTHOR]

This paper aims to analyze the nonlinear dynamic characteristics of hydro-turbine governing system with downstream surge tank and sloping ceiling tailrace tunnel and reveal their combined effect mechanism on stability. First, the nonlinear mathematical model of hydro-turbine governing system is presented. Second, the Hopf bifurcation theory is adopted, and the stability performances of hydro-turbine governing system under different sectional areas of downstream surge tank are analyzed and verified. Finally, the combined effect of downstream surge tank and sloping ceiling tailrace tunnel on stability is investigated and the design methods are proposed. The results indicate that: The dynamic response process of hydro-turbine governing system shows an obvious characteristic of wave superposition. Two types of bifurcation lines reflect the critical stability characteristics of the two subsystems and constitute the boundaries of the stable domain. The sloping ceiling tailrace tunnel cannot make an obvious change of the stability performances of the subsystem of penstock - hydro-turbine unit, but it has significant effect on the stability performances of the subsystem of downstream surge tank - sloping ceiling tailrace tunnel. The larger aspect ratio or smaller ceiling slope gradient results in better stability of the subsystem of downstream surge tank - sloping ceiling tailrace tunnel. [ABSTRACT FROM AUTHOR]

Highlights • The stability properties of the cell transmission traffic model are analyzed. • The capacity drop phenomenon is considered. • The steady-state flow may be lower than the maximum value in the open-loop system. • The proposed variable speed limit controller guarantees maximum flow rate for all possible scenarios and initial conditions. Abstract The cell transmission traffic flow model (CTM) has attracted considerable interest in the field of transportation due to its simplicity as well as the ability to capture most of the macroscopic traffic flow characteristics. The stability properties of the CTM under different demand and capacity constraints are not always obvious. In addition, the impact of microscopic phenomena such as forced lane changes at bottlenecks leading to capacity drop is not captured by the CTM. In this paper, we start with a single section and modify the CTM to account for capacity drop. We analyze the stability properties of the CTM under all possible demand and capacity constraints as well as all possible initial density conditions. The analysis is used to motivate the design of variable speed limit (VSL) control to overcome capacity drop and achieve the maximum possible flow under all feasible traffic situations. The results are extended to multiple sections, where the stability properties of the open-loop system are analyzed and a VSL control scheme is designed and shown to achieve the objective of maximizing the traffic flow under different demand and capacity constraints. Unlike the open loop system where an infinite number of equilibrium points exist under certain demand levels, the proposed nonlinear VSL scheme guarantees exponential convergence to a unique equilibrium point that corresponds to maximum possible flow and speed under all possible demand levels and capacity constraints. [ABSTRACT FROM AUTHOR]

Abstract The emergent scenario claims that our universe stems from an Einstein static universe, and provides a possible way to avoid the big bang singularity. A successful Einstein static universe requires to be stable past eternally against both homogeneous and inhomogeneous scalar perturbations. In this paper, we study the stability of Einstein static universes in general scalar–tensor theory with non-minimal derivative coupling by analyzing scalar and tensor perturbations. Our results show that the Einstein static solutions are stable against both scalar and tensor perturbations, and the emergent scenario is viable to avoid the initial singularity in this theory. [ABSTRACT FROM AUTHOR]