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A novel method for finding the eigenvalues of a Sturm–Liouville problem is developed. Following the minimalist approach, the problem is transformed to a single first-order differential equation with appropriate boundary conditions. Although the resulting equation is nonlinear, its form allows us to find the general solution by adding a second part to a particular solution. This splitting of the general solution into two parts involves the Schwarzian derivative: hence, the name of the approach. The eigenvalues that correspond to acceptable solutions can be found by requiring the second part to correct the asymptotically diverging behavior of the particular solution. The method can be applied to many different areas of physics, such as the Schrödinger equation in quantum mechanics and stability problems in fluid dynamics. Examples are presented. [ABSTRACT FROM AUTHOR]

Using fiberglass bolts to reinforce a tunnel face is a practical auxiliary technology for ensuring tunnel face stability in soft ground. The reinforcing effect and the economics of this technology are significantly affected by bolt length. However, to date, the failure mechanism of bolt-reinforced tunnel faces with different bolt lengths has rarely been investigated. To reveal the failure mechanism of bolt-reinforced shallow tunnel faces, in this study, the stability of bolt-reinforced tunnel faces with different bolt lengths was investigated by using laboratory tests and numerical simulations, and a simplified theoretical model for practical engineering was proposed. The face support pressure and failure pattern for different bolt lengths during the face collapse process were obtained, and the influence of bolt length on face stability was clearly revealed. More specifically, the results show that face stability increases with increasing bolt length, and the reinforcing effect of face bolts is governed by the shear failure at the soil-grout interface first in the stable zone of the tunnel face and then in the failure zone. Once the bolt length in the stable zone is larger than that in the failure zone, face stability will not be improved with increasing bolt length; thus, this bolt length is referred to as the optimal bolt length Lopt. The Lopt value is slightly larger than the initial failure range (in the unreinforced condition) and can be approximately calculated by Lopt = (1 x 0.0133u)D (u is the friction angle of the soil, and D is the tunnel diameter) in practical engineering. Finally, a simplified theoretical model was established to analyse the stability of reinforced tunnel faces, and the results are in good agreement with both laboratory tests and numerical simulations. The proposed model can be used as an efficient tool for the design of face bolts. [ABSTRACT FROM AUTHOR]

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]

The strength of jointed rock is a fundamental factor in the slope stability of rock mass. This research investigates the effect of infill thickness on the strength of jointed rock specimens. Unlike previous studies involving artificial rock-like materials and saw-tooth surfaces, this work has been conducted on two natural types of sandstone with various rock surfaces. Natural low-plasticity clay of different thicknesses (1 mm to 3 mm) was used as the infill material. A series of shear box tests with a range of initial normal stresses from 0.5 MPa to 1.5 MPa were performed to obtain high-quality data regarding the shear strength of natural rock and to provide insights into the effect of infill and rock surface roughness on shear strength. The obtained results were also used to improve the current methods of rock strength predictions, which were initially designed to estimate the strength of artificial rock-like material. Based on the obtained laboratory data and the strength estimation using different methods, a newly proposed procedure was proved to provide more accurate estimations of the shear strength of jointed rock. [ABSTRACT FROM AUTHOR]

Fading memory is the capability of a physical system to approach a unique asymptotic behaviour, irrespective of the initial conditions, when stimulated by an input from a certain class. Standard stimuli from the AC periodic class typically induce fading memory effects in non-volatile memristors, as uncovered for the first time back in 2016. Very recently, a deep investigation of resistance switching phenomena in a TaOx resistive random access memory cell revealed the capability of the nano-device to exhibit one of two possible oscillatory behaviours, depending upon the initial condition, when subject to a particular periodic excitation. This interesting finding was, however, left unexplained. Bistability is the simplest form of local fading memory. In a system, endowed with local fading memory under a given stimulus, the initial condition does not affect the long-term behaviour of the state as long as it is drawn from the basin of attraction of either of the distinct coexisting state-space attractors (two limit cycles for the periodically forced memristor acting as a bistable oscillator). Here, the history of the system, encoded in the initial condition, is, thus, erasable only locally through ad hoc stimulation. Motivated by the discovery of local history erase effects in our resistive random access memory cell, this study applies a powerful system-theoretic tool, enabling the analysis of the response of first-order systems to square pulse train-based periodic stimuli, known as the time-average state dynamic route, to an accurate physics-based mathematical model, earlier fitted to the nano-device, to determine a strategy for specifying the parameters of an excitation signal, consisting of the sequence of two square pulses of opposite polarity per period so as to induce various forms of monostability or multistability in the non-volatile memristor. In particular, as an absolute novelty in the literature, experimental measurements validate the theoretical prediction on the capability of the device to operate as one of two distinct oscillators, depending upon the initial condition, under a specific pulse train excitation signal. The coexistence of multiple oscillatory operating modes in the periodically forced resistive random access memory cell, an example par excellence of their unique nonlinear dynamics, may inspire the development and circuit implementation of novel sensing and mem-computing paradigms. [ABSTRACT FROM AUTHOR]

This study assesses the effect of stone content on the stability of soil–rock mixture slopes and the dynamics of ensuing large displacement landslides using a material point strength reduction method. This method evaluates structural stability by incrementally decreasing material strength parameters. The author created four distinct soil–rock mixture slope models with varying stone contents yet consistent stone size distributions through digital image processing. The initial conditions were established by linearly ramping up the gravity in fixed proportionate steps until the full value was attained. Stability was monitored until a sudden shift in displacement marked the onset of instability. Upon destabilization, the author employed the material point method to reconstruct the landslide dynamics. Due to the substantial computational requirements, the author developed a high-performance GPU-based framework for the material point method, prioritizing the parallelization of the MPM algorithm and the optimization of data structures and memory allocation to exploit GPU parallel processing capabilities. Our results demonstrate a clear positive correlation between stone content and slope stability; increasing stone content from 10 to 20% improved the safety factor from 1.9 to 2.4, and further increments to 30% and 40% ensured comprehensive stability. This study not only sheds light on slope stability and the mechanics of landslides but also underscores the effectiveness of GPU-accelerated methods in handling complex geotechnical simulations. [ABSTRACT FROM AUTHOR]

Objectives. The study aimed to examine the use of biomechanical analysis in handball technique. Materials and methods. This review study followed the PRISMA standards for systematic reviews and meta-analyses. The study had to be published within the period of 2018 to 2023. The search procedure involved using the keywords (1) handball and (2) biomechanics. Scopus search engine was used in the study. Results. The search results on the database yielded 115 articles, which were adjusted according to the criteria into 11 articles. Conclusion. Biomechanical analysis that can be applied to handball techniques includes such aspects: distance travelled, speed, change of direction, joint angle, postural stability, movement pattern, and injury localization. [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 Journal of Southeast University (English Edition) is the property of Journal of Southeast University Editorial Office 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.)

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 purpose of this research was to determine whether some stability exercises performed on the floor exercise mat to increase core strength would improve the technical application level of students. Method: A sample of 39 young male students from a university (age = 22.1±1.2 years, height = 170.3±6.5 cm, weight 65.2±8.7 kg, Body Mass Index = 22.5±2.8) participated in the study. The participants were into the control group (n=19) and experimental group (n=20) completed pre-tests and post-tests. The CS was assessed by the Stability Movement Push-ups, Abdominals, Back, Pull-ups, Headstand. The results of the paired samples t-tests show that the experimental group had a significant improvement in the mean scores for all four movements on the post-test compared to the pre-test. The mean score for the push-ups increased from 4.9±1.2 to 7.5±1.3 (t(14)=-10.78, p<0.001), the mean score for the abdominals and headstand increased from 4.6±1.0 to 7.0±1.2 (t(14)=-10.14, p<0.001), the mean score for the back and handstand increased from 4.8±1.1 to 6.9±1.2 (t(14)=-7.86, p<0.001), and the mean score for the pull-ups increased from 4.7±1.0 to 7.3±1.1 (t(14)=-11.47, p<0.001). Since the p values of the four movements are lower than 0.001, it is seen that there is a statistically significant difference between the scores obtained in the pre-test and the scores obtained in the post-test. According to the results, working out the core muscles may help enhance the technical execution of stability exercises performed on the mat or floor. [ABSTRACT FROM AUTHOR]

Gamma radiation indicators are appropriate tools for monitoring visually whether or not the irradiation process has been carried out properly. Among chemical radiation indicators available worldwide, a few are suitable for monitoring low dose ranges (especially for blood irradiation, below 50 Gy). Addressing this scope, PVA Fricke gel was proposed in this work. Irradiation of the prepared PVA Fricke gel samples was performed by Co-60 gamma cell unit up to a dose of 80 Gy. Color change of the samples was observed from orange to purple proportional to increasing absorbed dose. Prepared samples were divided into three groups, kept at different environmental conditions, to investigate stability of the gel against temperature and light. Results revealed that the irradiated samples kept at dark and refrigerator were stable for seven days. Optical absorbance measurement of the samples also estimated pre- and post-irradiation color stability. The gel can be easily used to identify processed and unprocessed products in blood irradiation. Although the gel is designed to be a qualitative indicator, it is also a good quantitative dosimeter for gamma rays. [ABSTRACT FROM AUTHOR]

The majority of classical methods which analyze the stability of existing cracks are based on theorems which calculate the forces in a state of limit equilibrium and do not take into consideration the deformation of the structure and the internal constraints thereof. This is not entirely consistent with what exactly happens in reality. For this purpose, we have proposed this study which analyzes the stability of cracks by the stress intensity factor through the calculation of the J-Integral, which is used in the calculation of the stress intensity factor. The stress intensity factor is a mechanical parameter, its values play a very important role in predicting the cracked state of the structure, and when it takes a certain value which is equal to the toughness of the material, the crack will cause the rupture of the structure. There are several methods for calculating the stress intensity factor. We have chosen to calculate it using the energy method because the direct calculation of the latter poses a problem because of the secularity of the flow around the crack. In this paper, we used the J-Integral and the energy release time to calculate the stress intensity factor. We also calculated using the laws of country the growth rate and the necessary number of cycles for the propagation of a crack. [ABSTRACT FROM AUTHOR]

The current work investigates the behavior of a bamboo grid-reinforced slope, which utilized 2D numerical analyses using the finite element program MIDAS GTS NX (340) 2023 v1.1. The results and discussion of the study revealed the effectiveness and stability of the bamboo grid-reinforced slope. The percentage of safety factor increment for bamboo grid-reinforced slope is 80% compared to an unreinforced slope. Bamboo grids can reduce 92.54% of the total displacement of the slope. Applying a bamboo grid reduces horizontal stress, vertical stress, significant principal stress, minor principal stress, and total internal forces by 51.67%, 43%, 42.66%, 49.87%, and 23.54%, respectively. The numerical analyses showed that the bamboo grid was able to resist the applied loads and maintain its stability. Some researchers in their study found that PET geogrids provide better stability performance than other geogrids. As the geogrids are made up of different materials such as plastic, nylon, etc., they are not friendly to the environment. Bamboo is a biodegradable natural element that may be a suitable replacement for geogrid material. [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]

Punching shear is one of the possible failures that must be taken into consideration in designing concrete slabs and foundations. Several factors control the occurrence of this failure mechanism, such as slab thickness, concentrated loads, and the cross-section area of the supporting columns. The cross-section shape of columns may also affect the punching shear in flat slabs. Therefore, this research was specified to study the effect of the columns' cross-section shape on the punching shear in flat slabs by conducting a simulation analysis for two multi-story concrete buildings with a flat slab but with different structural stability systems, building layout, and column distribution, where five cross-section shapes (square, rectangular, circular, hexagonal, and octagonal) were tested. ETABS 2016 software was adopted for modeling and analysis to identify the optimum column shape leading to minimizing punching shear. Although the cross-section area and the reinforcement area of the columns were fixed while changing the models' column shapes, it was found, in both buildings, that hexagonal columns performed better than others under punching shear and provided the lowest punching shear ratio. In contrast, circular columns gave the lowest resistance. Octagonal, square, and rectangular columns, respectively, follow the hexagonal columns in resisting punching shear. [ABSTRACT FROM AUTHOR]

Slope instability issues could cause severe damage and endanger the population, especially when dams are concerned. Over the past years, more and more refined numerical approaches have been proposed to evaluate the slope stability. However, a criterion based on the lack of numerical convergence is generally considered to compute the safety factor with this kind of approaches, which may result in a dramatic increase in the overall computation time for the probabilistic assessment of the safety factor (e.g., using Monte Carlo simulations that require the automation of a large number of simulations). This paper proposes an original approach coupling the shear strength reduction technique with the second-order work criterion. This approach is implemented in the open finite element software Cast3M, version 22.0. The relevance and efficiency of the developed approach is illustrated with two case studies: a heuristic slope and an existing earth dam. Safety factors similar to those calculated by classical approaches are obtained, but without pushing the calculation to the point of non-convergence. Among other advantages described in the paper, the proposed approach makes it possible to compute safety factors using a rational and physically based criterion, while facilitating probabilistic calculations. [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]

The physical stability of solid--liquid fuel is a factor that needs to be considered for fuel product practicability for storage and transportation. To determine the Influence of liquid bridge force on physical stability, two detection devices were designed. The laws obtained from microscopic experiments are used to verify the physical stability of fuel under different component ratios. The liquid bridge force is found to increase with the droplet volume. Multiliquid bridges above one critical saturation can generate significant resultant forces compared to single-liquid bridges of the same volume. There exist four states of solid--liquid mixed fuel with increasing liquid saturation rate. The liquid bridge force between the solid and liquid plays a dominant role in the physical stability of the first three states. There may be two stages involved in the stratification process for state 4 fuel, and the liquid viscosity is another factor that cannot be ignored. In the process of selecting a fuel ratio, a larger liquid bridge force between the components can be obtained by properly improving the wetting effect so that the fuel shows better physical stability. [ABSTRACT FROM AUTHOR]

Copyright of Revue Française de Géotechnique is the property of EDP Sciences 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.)

The shearing behavior of discontinuities is one of the factors with major influence on rock slope stability analysis, which is predictable when adopting different analytical models. However, these methodologies, generally of a purely deterministic nature, do not allow an assessment of the influence of the variability of the input parameters of the models on the shear behavior of unfilled rock discontinuities and, consequently, on the risk involved in the rock slope stability analyses. The purpose of this article is to present a methodology for rock slope risk assessment based on the development of a model to predict the shear behavior of unfilled rock discontinuity considering the variability of its input parameters, using a Mamdani fuzzy controller. The input variables of the model are the boundary normal stiffness and initial normal stress acting on the discontinuity, its roughness, the uniaxial compressive strength, the basic angle of friction of the intact rock and the shear displacement imposed on the discontinuity. The model outputs are the membership functions for the shear strength and dilation of the unfilled rock discontinuity, and from which the membership function can be defined for the factor of safety of the rock slope considering the failure mechanism governed by discontinuity. The results reveal the use and importance of fuzzy logic and fuzzy number operations in assessing the risk in rock slopes and may be used even in situations where there are major uncertainties on the existing information of the characteristics of the unfilled discontinuities. [ABSTRACT FROM AUTHOR]

Surface reconstruction as common phenomenon during catalysis complicates the prediction and modeling on catalytic activity of the nanoalloy, hence developing a stable structure to be resistant to surface restructuring would provide an ideal prototype for substantial and reliable mechanism analysis. Herein, the single‐twinned structure in inverse AgPdF catalyst is constructed to enhance the catalytic activity and stability for the formate oxidation reaction (FOR). The single‐twinned AgPdF nanoalloy (t‐AgPdF) catalyst exhibits an enhanced peak current density of 4.6 A mgPd−1, a reduced onset potential of 0.44 V, a higher activity retention of 55.7% after 600 cycles, and a longer activity retention time of 55.9 h. Additionally, the t‐AgPdF catalyst presents a higher hydrogen generation rate of 1.11 mL mgPd−1 than that of single‐crystalline AgPd nanoalloy (AgPd) catalyst, and density functional theory calculations reveal that t‐AgPdF(111) surface exhibits a reduced activation energy of 0.59 eV for formate decomposition reaction. Impressively, the t‐AgPdF maintains compressive and tensile strain state along the Σ3 twin boundaries before and after the FOR, in contrast to AgPd. This is the first time to reveal that the nanotwinned structures contribute inverse t‐AgPdF catalysts the catalytic active sites with stable strain state since starting reaction for the FOR. [ABSTRACT FROM AUTHOR]

To guarantee a durable pavement construction that only needs a little care, it is crucial to manage problematic soil conditions properly and prepare the foundation. Some organizations remove soils since they have realized they do not function as well as other materials (for example, a state specification dictating that frost susceptible loess could not be present in the frost penetration zone). Nevertheless, there are more advantageous or desirable courses of action than this (e.g., excavation might create a disturbance, plus additional issues of disposal and removal). The subgrade conditions described in the preceding section may be improved by stabilization, offering an alternative solution. It is impossible to overstate the importance of ensuring a homogeneous soil profile in terms of density, moisture content, and textural categorization in the top section of the subgrade. Thru soil sub-cutting or other stabilizing methods, this consistency may be attained. Additionally, stabilization may be utilized to prevent swelling in expansive materials, create a weather-resistant work platform, enhance soil workability, and limit issues with frost heave. Alternative stabilizing techniques will be discussed in this part, and advice for choosing the best technique will be adequately provided. The current review paper aims to identify bridge issues related to soft soil and takes two ways of soft soil stabilization: chemical and mechanical. The finding of both methods show that the compressive strength and settlement have been improved after using waste materials; therefore, using waste materials as a cement replacement is considered one of the expansive utilized methods in most construction applications and bridges of that applications. [ABSTRACT FROM AUTHOR]

Optimum mud weight estimation in wellbore is one of the most important steps to prevent instability. In wellbore stability studies, media (rock) is usually assumed to be isotropic but errors occur when weak bedding planes cause the rocks to be anisotropic. In this study the effect of weak bedding plane in stability of wellbore was studied. Also, the effect of bedding plane parameters on stability of vertical and horizontal wellbore was investigated. Through the use of the geometric relations of bedding plane and wellbore, new equations were presented to calculate the attack angle. Sensitivity analysis on the dip and dip direction of weak bedding plane in the vertical and horizontal wellbore were also performed. On the basis of the porous elasticity theory and Jaeger theories, an analytical model was proposed to analyze the wellbore stability with regard to dip and dip direction of weak bedding plane. A code in MATLAB was written based on analytical model and effect of dip and dip direction of weak bedding plane can be reviewed. By using real data from a wellbore, a comparative analysis was carried out between the new analytical model and the intact rock failure model. Minimum drilling mud weight was calculated in two phases, without weak bedding planes and with weak bedding planes. Results show that the existence of weak bedding planes causes more instability in the wellbore in some azimuths and deviations. Dip and dip direction of weak bedding planes have a great impact on the wellbore stability and in the horizontal wellbore according to dip and dip direction, the optimum wellbore trajectory is different. By applying the code, geomechanical engineers can calculate the amount of mud weight based on the dip and dip direction of the weak bedding plane. [ABSTRACT FROM AUTHOR]

Early surgical stabilization of rib fracture (SSRF) improves outcomes in patients with flail physiology and severely displaced fractures. We present two cases of patients with severe chest injury and large flail segment who underwent SSRF while on veno-venous extracorporeal membrane oxygenation (VV-ECMO). The patients developed respiratory failure within 24 hours of admission requiring VV-ECMO. The extent of their chest wall injury limited pulmonary mechanics prohibiting transition off VV-ECMO. Therefore, SSRF was performed on hospital days 2 and 3 and while on VV-ECMO support. Stabilizing the chest wall allowed for improved ventilation and successful decannulation from VV-ECMO on postoperative days 3 and 4. Ultimately, both achieved a functional recovery and were discharged home. These cases demonstrate a unique thoracic damage control strategy wherein SSRF is performed while on VV-ECMO. Improving chest stability and pulmonary mechanics with SSRF allowed for safe transition off VV-ECMO and achieved a favorable long-term outcome. [ABSTRACT FROM AUTHOR]

To compare the amount of bone expansion, bone density change, and implant primary stability with an osseodensification technique to a conventional drilling protocol. Materials and Methods: Twenty-four bovine rib segments (20 × 25 × 4 mm) with a 1-mm outer layer of cortical bone were randomly divided into two groups: an osseodensification group and a conventional drilling group. Each bone sample received one 4.1 × 10–mm implant. The density of the peri-implant bone before and after osteotomy was measured. After implant placement, primary stability was assessed. A laser surface scanner was used before and after implant placement to compare the dimension of crestal bone width and volumetric expansion. Histomorphometric analysis was performed to compare the bone-to-implant contact percentage (BIC%) of the two groups. Results: The peripheral and apical bone mineral density around the implants was significantly increased, and a statistically significantly higher peripheral BIC% was found in the osseodensification group. A significant increase in volume and bone width after implant placement was found in both groups. However, there were no significant differences in volume and bone width change at all three locations and in implant stability between the osseodensification and conventional drilling protocols. Conclusion: Within the limitations of this study, the osseodensification protocol increased the bone mineral density and primary bone-to-implant contact. Also, this study suggests that implant placement by osseodensification or conventional drilling can increase ridge dimensions in narrow alveolar ridges. [ABSTRACT FROM AUTHOR]

To evaluate the insertion torque at the equicrestal and subcrestal positions of three implant designs in synthetic polyurethane blocks simulating different bone conditions. Materials and Methods: Overall, 72 implants with three different designs (two conical and one cylindrical) were inserted at equicrestal and subcrestal positions (–2 mm) into polyurethane blocks simulating the anterior (0.32 g/cm³) and posterior (0.48 g/cm³) regions of the maxilla. The final insertion torque of all implants was measured using a digital torque meter, and the results were evaluated and statistically analyzed. Results: For all implant systems, insertion torque decreased significantly when placed at the subcrestal position (P < .05), except for cylindrical implants placed in the bone blocks with high cancellous density. The implants with higher body conicity and square threads had higher insertion torque values than the cylindrical and conical implants with a lower body conical angle and trapezoidal threads. The implants inserted into higher-density blocks showed greater stability. Conclusion: The different implant systems lost insertion torque in a nonuniform manner at the subcrestal position and varied according to bone density. Implant design significantly influenced the initial stability at the equicrestal and subcrestal positions, especially in lower-density bone. [ABSTRACT FROM AUTHOR]

Bone density and implant primary stability parameters have been introduced that are based on calculating (1) the average of the instantaneous torque needed to keep the rotation speed of a bone density probe constant while it descends into bone or (2) the integral of the instantaneous torque-depth curve at implant insertion (I), a quantity that is equal to the insertion energy multiplied by a constant. This study aimed to determine how these two quantities are affected by the presence and thickness of a cortical bone layer. Materials and Methods: An instantaneous torquemeasuring micromotor was used to measure the density of six double-layer polyurethane foam blocks mimicking different cortical/cancellous bone combinations. Twenty measurements per block were collected, averaged, and compared. The insertion torque and the integral (I) of the instantaneous torque-depth curve at implant insertion were recorded when 20 3.75 × 12-mm cylindrical implants were inserted in each of nine blocks, including three single-layer blocks simulating the absence of a cortical layer, under three final cortical (countersink) preparations: 4.0, 3.7, and 3.5 mm. The relationship between the insertion torque, the integral of the instantaneous torque-depth curve at implant insertion (I), cortical thickness, and the final diameter preparation were investigated with regression and best-fit slope analyses. Results: Bone density measurements showed that the average of the instantaneous torque at probing allowed differentiation of five of six different bone classes (hard-hard, hard-normal, hard-soft, normal-normal, normal-soft, soft-soft); the post hoc analysis of variance (ANOVA) comparisons were all statistically significant except for the hard-soft–normal-soft pair. The insertion torque and the integral (I) of the instantaneous torque-depth curve at implant insertion increased proportionally with cortical bone thickness (Pearson’s r > 0.96 in all cases). Conclusion: When the final preparation varied from 3.7 mm to 3.5 mm, the insertion torque–thickness plot slope did not change significantly, while that of the instantaneous torquedepth curve integral (I)–thickness plot did change, suggesting that the torque-depth curve at implant insertion integral (I) may detect the increase in implant stability consequent to slight anatomical changes or changes in the site preparation protocol better than the insertion torque when measuring the cortical bone layer stress while undergoing insertion. These findings concerning bone density and primary stability should be investigated further using different experimental settings. If confirmed, they might generate improvements in the predictability of implant and prosthetic rehabilitation outcomes. [ABSTRACT FROM AUTHOR]

We prove a version of the strong Taylor's conjecture for stable graphs: if G is a stable graph whose chromatic number is strictly greater than Æ2.@0/then G contains all finite subgraphs of Shn.!/and thus has elementary extensions of unbounded chromatic number. This completes the picture from our previous work. The main new model-theoretic ingredient is a generalization of the classical construction of Ehrenfeucht-Mostowski models to an infinitary setting, giving a new characterization of stability. [ABSTRACT FROM AUTHOR]

Much of the focus of neuronal cell biology has been devoted to growth cone guidance, synaptogenesis, synaptic activity, plasticity, etc. The axonal shaft too has received much attention, mainly for its astounding ability to transmit action potentials and the transport of material over long distances. For these functions, the axonal cytoskeleton and membrane have been often assumed to play static structural roles. Recent experiments have changed this view by revealing an ultrastructure much richer in features than previously perceived and one that seems to be maintained at a dynamic steady state. The role of mechanics in this is only beginning to be broadly appreciated and appears to involve passive and active modes of coupling different biopolymer filaments, filament turnover dynamics and membrane biophysics. Axons, being unique cellular processes in terms of high aspect ratios and often extreme lengths, also exhibit unique passive mechanical properties that might have evolved to stabilize them under mechanical stress. In this review, we summarize the experiments that have exposed some of these features. It is our view that axonal mechanics deserves much more attention not only due to its significance in the development and maintenance of the nervous system but also due to the susceptibility of axons to injury and neurodegeneration. [ABSTRACT FROM AUTHOR]

Hypertidal estuaries are very dynamic environments characterized by high tidal ranges (> 6 m) that can experience rapid rates of bank retreat. Whilst a large body of work on the processes, rates, patterns, and factors driving bank erosion has been undertaken in fluvial environments, the process mechanics affecting the stability of the banks with respect to mass failure in hypertidal settings are not well-documented. In this study, the processes and trends leading to bank failure and consequent retreat in hypertidal estuaries are treated within the context of the Severn Estuary (UK) by employing a combination of numerical models and field-based observations. Our results highlight that the periodic fluctuations in water level associated with the hypertidal environment drive regular fluctuations in the hydrostatic pressure exerted on the incipient failure surfaces that range from a confinement pressure of 0 kPa (at low tide) to ∼ 100 kPa (at high tide). However, the relatively low transmissivity of the fine-grained banks (that are typical of estuarine environments) results in low seepage inflow/outflow velocities (∼ 3 × 10 -10 m s -1), such that variations in positive pore water pressures within the saturated bank are smaller, ranging between about 10 kPa (at low tide) and ∼ 43 kPa (at high tides). This imbalance in the resisting (hydrostatic confinement) versus driving (positive pore water pressures) forces thereby drives a frequent oscillation of bank stability between stable (at high tide) and unstable states (at low tide). This transition between stability and instability is found not only on a semidiurnal basis but also within a longer time frame. In the spring-to-neap transitional period, banks experience the coexistence of high degrees of saturation due to the high spring tides and decreasing confinement pressures favoured by the still moderately high channel water levels. This transitional period creates conditions when failures are more likely to occur. [ABSTRACT FROM AUTHOR]

This article presents some historical developments in the theory of stability in mechanics from a dynamical systems point of view, focusing on mathematical methods from the earliest developments (Newton) and explaining some classical and some recent methods used, including Riemannian structures, entropy and notions of stability in dynamics. [ABSTRACT FROM AUTHOR]

To reduce the recoil and improve the stability of small arms, a muzzle brake compensator is attached to the muzzle of the barrel. This device uses the kinetic energy of the powder gas escaping from the bore after the bullet is fired. In this paper, the authors present the determination of the thermo-gas-dynamic model of the operation of a muzzle brake compensator and an example of calculating this type of muzzle device for the AK assault rifle using 7.62 × 39 mm ammunition. The results of the calculation allowed for obtaining the parameters of the powder gas flow in the process of flowing out of the muzzle device, as well as the change in the momentum of the powder gas's impact on the muzzle device. The model proposed in the article provides the basis for a quantitative evaluation of the effectiveness of using the muzzle device in stabilizing infantry weapons when firing. [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]

China has abundant coal resources, and the distribution of coal seams is complex. Thick coal seams account for more than 45% of all coal seams. Fully mechanized top coal caving mining has the advantages of large production, high efficiency, and low cost. In fully mechanized caving mining, especially in fully mechanized caving mining of extra-thick coal seams, the mining space is ample, the mine pressure is severe, and the roadway maintenance is complex. As a result, it is necessary to summarize and discuss the gob-side entry driving of fully mechanized caving in theory and technology, which will help to promote the further development of fully mechanized caving gob-side entry driving technology. First, in recent years, the research hotspots of gob-side entry driving have focused on the deformation mechanism and the control method of the roadway surrounding rock. Secondly, this paper discusses the theoretical models of the "triangle-block" and "beam" for the activity law of the overlying strata in gob-side entry driving, including the lateral breaking "large structure" model, compound key triangle block structure model in the middle and low position, the high and low right angle key block stability mechanics model, elastic foundation beam model, low-level combined cantilever beam + high-level multilayer masonry beam structure model, and the vertical triangular slip zone structure model. It introduces the "internal and external stress field theory" and the "stress limit equilibrium zone model". Thirdly, it summarizes several numerical simulation analysis methods in different conditions or research focuses and selects appropriate constitutive models and simulation software. Finally, it introduces surrounding rock control technology, including two ribs, the roof, and under challenging conditions. It provides a method reference for support in similar projects. [ABSTRACT FROM AUTHOR]

This part of ANSI S2.72 / ISO 2631 defines methods for the measurement of periodic, random and transient whole-body vibration. It indicates the principal factors that combine to determine the degree to which a vibration exposure will be acceptable. Informative annexes indicate current opinion and provide guidance on the possible effects of vibration on health, comfort and perception and motion sickness. The frequency range considered is ⎯ 0.5 Hz to 80 Hz for health, comfort and perception and ⎯ 0.1 Hz to 0.5 Hz for motion sickness. Although the potential effects on human performance are not covered, most of the guidance on wholebody vibration measurement also applies to this area. This part of ANSI S2.72 / ISO 2631 also defines the principles of preferred methods of mounting transducers for determining human exposure. It does not apply to the evaluation of extreme-magnitude single shocks such as occur in vehicle accidents. This part of ANSI S2.72 / ISO 2631 is applicable to motions transmitted to the human body as a whole through the supporting surfaces: the feet of a standing person, the buttocks, back and feet of a seated person or the supporting area of a recumbent person. This type of vibration is found in vehicles, in machinery, in buildings and in the vicinity of working machinery. [ABSTRACT FROM AUTHOR]

Hygrothermal treatment is an effective method for improving the dimensional stability of bamboo. In this study, changes in the physicochemical properties of Neosinocalamus affinis after hygrothermal treatment were comprehensively investigated: the hemicellulose content decreased, C=O in the acetyl group and the hydroxyl content decreased and xylan was partially degraded. The dimensional stability of N. affinis gradually increased with temperature, and optimal values were obtained at 220 °C, as indicated by a 16.5% decrease in anti-swelling efficiency and a 93.7% increase in contact angle. Alterations in the macromolecular structure of lignin were also observed: the contents of β-O-4 linkages and p-coumarate decreased by 54.3% and 23.9%, respectively; β-5 linkages disappeared at 220 °C, as determined by heteronuclear single quantum correlation spectroscopy. However, the maximum values for crystallinity, nano indentation elastic modulus, and hardness were reached at 180 °C and were higher than those of the untreated samples by 8.6%, 19.9%, and 23.5%, respectively. With the combined application of physical mechanics and dimensional stability, hygrothermal treatment at 180 °C and 100% relative humidity was proved to exert the optimal effects on N. affinis. These results provide new and comprehensive insights into the mechanism allowing the modification of N. affinis by hygrothermal treatment. [ABSTRACT FROM AUTHOR]

There has been a global effort in the past decade, especially in major coal-producing countries, toward understanding the mechanics involved in the stability of coal mine ribs. Buckling and spalling of mine ribs are known to have an impact on their stability and degradation. The generation, propagation, and coalescence of cracks in mine pillar ribs are significantly affected by the overburden depths. In addition, the in situ stress magnitudes tend to affect the rib damage process. High horizontal stresses and increased depths can lead to unfavorable stress conditions, inducing coal mass damage and strength loss. Understanding the dynamics involved in rib behavior will inform better rib control practices. This study intended to assess the effect of mining depth, mining height, and supports on coal mine rib stability. In this research, the response of the coal mass was studied using distinct element modeling to better understand the failure process of coal mine ribs. The study confirmed mining depth as a significant factor controlling the rib loading and failure mechanism. In addition, increased mining heights increased the rib deformation and failure process. The evaluated support effect revealed that at shallower depths, shorter bolt lengths are sufficient to control rib stability. Increasing the bolt length for depths greater than 250 m is in order, but higher depths do not correlate with longer supports. The approach used in this study demonstrated its capacity to be used in designing rib support requirements and understanding coal mass and support mechanisms. [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]

A mixture of cement, fine aggregate and coarse aggregate is known as concrete. It plays an important role in infrastructure development like buildings, bridges and industrial structures etc. Long term performance of buildings without deterioration helps economics of nation. High performance concrete (HPC) is a concrete which shows special performance than conventional concrete. This leads to usage of admixtures to improve concrete performance. On the other side cost of concrete ingredients plays vital role, this leading to usage of alternative materials which is economic in its production. This requirement made the investigators to find new replacement for concrete ingredients which should improve long term performance and stability of structures. This research focuses on strength and durability characteristics of M60 concrete with partial replacement of sand with ROBO Sand (crusher dust) and cement with Ground Granulated Blast furnace Slag (GGBFS), it is a byproduct in manufacture of iron in steel industry, usage of these replacement materials are more eco friendly. To study the strength and durability characteristics the following properties should be studied such as Compressive strength, Chloride penetration (RCPT test), Permeability (Sorptivity test), Stress strain, Acid resistance. As a part of study strength characteristics were studied by testing compressive strength of cubes. It is found that different percentage of replacement of cement with GGBFS and sand with ROBO Sand helped in improving the strength of the concrete more over equal to normal mix concrete. [ABSTRACT FROM AUTHOR]

This paper mainly concerns the area growth and bottom spectrum of complete stable minimal surfaces in a three-dimensional manifold with scalar curvature bounded from below. When the ambient manifold is the Euclidean space, by an elementary argument, it is shown directly from the stability inequality that the area of such minimal surfaces grows exactly as the Euclidean plane. Consequently, such minimal surfaces must be flat, a well-known result due to Fisher-Colbrie and Schoen as well as do Carmo and Peng. In the case of general ambient manifold, explicit area growth estimate is also derived. For the bottom spectrum, a self-contained argument involving positive Green's function is provided for its upper bound estimates. The argument extends to stable minimal hypersurfaces in a complete manifold of dimension up to six with sectional curvature bounded from below. [ABSTRACT FROM AUTHOR]

Backlash nonlinearity inevitably exists in the actuator of tank horizontal stabilizer and has adverse effect on the system control performance, however, how to effectively eliminate its effect remains a pending issue. To solve this problem, a robust adaptive precision motion controller is presented in this paper to address uncertainties and unknown actuator backlash of tank horizontal actuator. The controller handles the modeling uncertainties including parameter uncertainties and unmodeled disturbances by integrating adaptive feedforward compensation and continuous nonlinear robust law. Based on the backstepping method, a smooth backlash inverse model is constructed by combining the adaptive idea. Meanwhile, the unknown backlash parameters of the system can be approximated through the parameter adaptation, and the impact of the actuator backlash nonlinearity is effectively compensated via the inverse operation, which can availably improve the tracking performance. Moreover, the adaptive law can update the disturbance ranges of tank horizontal stabilizer online in real time, which enhances the feasibility in practical engineering applications. Furthermore, the stability analysis based on Lyapunov function shows that with the existence of unmodeled disturbances and unknown actuator backlash, the designed controller guarantees excellent asymptotic output tracking performance. Extensive comparative results verify the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]