Relative Deformation Research Articles

Tracking patellar osteophytes to detect osteoarthritis

ABSTRACT The presence of bone spurs (osteophytes) in knee-joints provides an indication of the onset of osteoarthritis and related deformities in patients. The shape of the patella bone at knee-joint undergoes various changes with the advancement of the disease, which may be discerned accurately from X-ray images. The main objective of this work is to identify the presence of osteophytes in the patella bone of knee-joint. Geometric features are extracted that highlight protrusions present on the bone surface from lateral views of X-ray images. The patella region is extracted from the image by performing texture-based segmentation followed by adaptive thresholding. Characteristic features are extracted from the segmented patella using derived novel measures based on differential chain code of the contour and convex hull. Linear support vector machine is used to classify diseased test-cases from healthy ones using the extracted features. Experimental results demonstrate the capability of the proposed image-analysis tool for detecting osteoarthritis with average accuracy of 93.75%.

Identification, reproduction, and control of vehicle roll vibration

The human body is extremely sensitive to roll vibration, which is also an important indicator for evaluating vehicle comfort. In order to improve the ability of anti-roll vibration of vehicles, the methods of mathematical modeling, dynamic simulation, and vibration test are used in this paper. The generation mechanism, dynamic change law, and key influencing factors of the roll vibration are analyzed. The analysis results include: the dynamic simulation results are in good agreement with the test results, and the use of the simulation model is beneficial to the analysis and control of the roll vibration; the roll vibration is caused by the relative dynamic deformation of the left and right suspensions, and the larger the relative deformation, the more obvious the roll vibration; the optimization of the position and damping of the shock absorber is conducive to the control of roll vibration, which greatly improves the comfort of the vehicle. The research results provide theoretical basis and reference for grasping the characteristics of the roll vibration and vibration reduction design.

Fiber optic monitoring of an anti-slide pile in a retrogressive landslide

Anti-slide piles are one of the most important reinforcement structures against landslides, and evaluating the working conditions is of great significance for landslide mitigation. The widely adopted analytical methods of pile internal forces include cantilever beam method and elastic foundation beam method. However, due to many assumptions involved in calculation, the analytical models cannot be fully applicable to complex site situations, e.g. landslides with multi-sliding surfaces and pile-soil interface separation as discussed herein. In view of this, the combination of distributed fiber optic sensing (DFOS) and strain-internal force conversion methods was proposed to evaluate the working conditions of an anti-sliding pile in a typical retrogressive landslide in the Three Gorges reservoir area, China. Brillouin optical time domain reflectometry (BOTDR) was utilized to monitor the strain distribution along the pile. Next, by analyzing the relative deformation between the pile and its adjacent inclinometer, the pile-soil interface separation was profiled. Finally, the internal forces of the anti-slide pile were derived based on the strain-internal force conversion method. According to the ratio of calculated internal forces to the design values, the working conditions of the anti-slide pile could be evaluated. The results demonstrated that the proposed method could reveal the deformation pattern of the anti-slide pile system, and can quantitatively evaluate its working conditions.

Investigation of Experimental Devices for Finger Active and Passive Tactile Friction Analysis

Complicated tribological behavior occurs when human fingers touch and perceive the surfaces of objects. In this process, people use their exploration style with different conditions, such as contact load, sliding speed, sliding direction, and angle of orientation between fingers and object surface consciously or unconsciously. This work addressed interlaboratory experimental devices for finger active and passive tactile friction analysis, showing two types of finger movement. In active sliding experiment, the participant slid their finger freely against the object surface, requiring the subject to control the motion conditions themselves. For passive sliding experiments, these motion conditions were adjusted by the device. Several analysis parameters, such as contact force, vibration acceleration signals, vibration magnitude, and fingerprint deformation were recorded simultaneously. Noticeable friction differences were observed when comparing active sliding and passive sliding. For passive sliding, stick-slip behavior occurred when sliding in the distal direction, evidenced by observing the friction force and the related deformation of the fingerprint ridges. The employed devices showed good repeatability and high reliability, which enriched the design of the experimental platform and provided guidance to the standardization research in the field of tactile friction.

Methods for determining the critical deformations of wood with various moisture content

During construction of bridges, the possibility of flooding periods should be considered. Therefore, it is necessary to understand the degree of possible deformation of wooden structures and calculate the limit of their plasticity and elasticity at different values of moisture content. Thus, the purpose of study is to find the method for determining the relative critical deformations of wood with different moisture content and analyse the dynamics of their change. Problems of a deformable solid material were investigated by the analysis of a model of complete deformation diagram “stress σс – deformation uс ”, methods of mathematical statistics, and systematic analysis of experimental results. This study allowed formulating the method for determining the relative critical deformations of solid wood at different moisture levels by axial compression along the fibres of experimental samples. Based on the experiment results, the formula for determining the relative critical deformations of solid wood with different moisture was proposed. The dynamics of changes in critical relative deformations at different moisture, and its elastic and plastic components were presented. It was found that in case of drying wood from 30 to 12%, the plastic component of relative critical deformations decreases and the elastic one, on the contrary, increases. The findings can be used in the deformation calculation methodology for wooden elements and structures of bridges, hydraulic structures, buildings, taking into account the changes in the moisture content of the material

Numerical simulation on damage behaviors of tile-mortar interface induced by mortar shrinkage and temperature cycles

In this study, the initiation and evolution of interfacial damage between tile and mortar induced by mortar shrinkage, temperature cycles and their coupling actions were investigated and compared based on a novel fatigue cohesive zone model for the first time. Firstly, the fatigue cohesive zone model was established by coupling a bi-linear cohesive zone model with a fatigue damage evolution model and verified by comparing with experimental values. Then, the deformations and stresses at tile-mortar interface under various scenarios of mortar shrinkage and temperature cycles were calculated. Finally, the interfacial damage characteristics were systematically studied in terms of three indices including damage degree, damage area and debonding area. Results showed that a larger shrinkage of mortar brought about a higher relative movement and stronger interfacial stress, thereby accelerating the propagation of interfacial damage from the rim to the center. In the case of considerably low mortar shrinkage, the interfacial relative deformations were too low to provoke any interfacial damage. The increases of temperature amplitudes promoted the accumulation and propagation of interfacial damage, causing an earlier appearance of debonding. The effects of cooling cycles were much greater than those of heating cycles. The damage degrees induced by cooling cycles were equivalent to those by mortar shrinkage in certain cases. Although considerably low shrinkage failed to initiate interfacial damage, its coupling with temperature cycles significantly aggravated interfacial damage, in particular for debonding area remarkably increased after 1000 cooling cycles.

Hopf Structure for the q-Lévy-Meixner Oscillator Algebra

The main purpose of this paper is to investigate a generalized oscillator algebra, naturally associated with the [Formula: see text]-Lévy-Meixner polynomials. We solve the problem of the Hopf algebraic structure for the [Formula: see text]-deformed Lévy-Meixner oscillator algebra based on the one-parameter deformation of canonical commutation relations.

Radial Wall Strain Assessment From AI-Assisted Angiography: Feasibility and Agreement With OCT as Reference Standard.

High-strain spots in coronary arteries are associated with plaque vulnerability and predict future events. Artificial intelligence currently enables the calculation of radial wall strain (RWS) from coronary angiography (RWSAngio). This study aimed to determine the agreement between novel RWSAngio and RWS derived from optical coherence tomography (OCT) followed by finite element analysis, as the established reference standard (RWSOCT). All lesions from a previous OCT study were enrolled. OCT was automatically coregistered with angiography. RWSAngio was computed as the relative luminal deformation throughout the cardiac cycle, whereas RWSOCT was analyzed using finite element analysis on OCT cross-sections at 1-mm intervals. The luminal deformation in the direction of minimal lumen diameter was used to derive RWSOCT, using the same definition as RWSAngio. The maximal RWSOCT and RWSAngio at healthy segments adjacent to the interrogated lesion were also analyzed. Finite element analysis was performed in 578 OCT cross-sections from 45 lesions stemming from 36 patients. RWSAngio showed good correlation and agreement with RWSOCT (r = 0.91; P < .001; Lin coefficient = 0.85). RWSAngio in atherosclerotic segments was significantly higher than that in healthy segments (12.6% [11.0, 16.0] vs 4.5% [2.9, 5.5], P < .001). The intraclass correlation coefficients for intra- and interobserver variability in repeated RWSAngio analysis were 0.92 (95% CI, 0.87-0.95) and 0.88 (95% CI, 0.81-0.92), respectively. The mean analysis time of RWSOCT and RWSAngio for each lesion was 95.0 ± 41.1 and 0.9 ± 0.1 minutes, respectively. Radial wall strain from coronary angiography can be rapidly and easily computed solely from angiography, showing excellent agreement with strain derived from coregistered OCT. This novel and simple method might provide a cost-effective biomechanical assessment in large populations.

Identification of the torsion coefficient of bolts in slip-critical connections

Introduction. The article proposes a method for identifying the coefficient of torsion of a high-strength bolt in the laboratory environment. The coefficient is found by determining the relative deformation of a drawn bolt using load cells. This method requires specialized equipment and a test bench, and it can be used to study the behavior of bolts. The value of the torsion coefficient is necessary to ensure the appropriate bolt tension force, since according to current friction concepts of bolted connections involving high-strength bolts, the design behavior of a bolted connection is ensured by the appropriate bolt tension force, determined using the required torque. Otherwise, the actual behavior of a bolt differs from its design behavior, since only a pre-set tension force ensures the necessary bearing capacity of a bolted connection in the friction planes.&#x0D; &#x0D; Materials and methods. Specimens of bolts under study are made according to the German standard DIN931 with a strength of 10.9, and the size M14 × 220; their nuts comply with the German standard DIN934 with a strength of 10 and the size M14. Instron 1000HDX tension testing machine was used to make a diagram describing the performance of steel bolts. Nut tension was determined using NOGRAU NTW24-034R torque control key, and bolt elongation was controlled using FLA 5-11 strain gauges and the National Instruments data collection system.&#x0D; &#x0D; Results. A new method for monitoring the measurement of the torsion coefficient of high-strength bolts was tested and proposed in furtherance of the research conducted by the authors.&#x0D; &#x0D; Conclusions. As a result of testing, a change in the torsion coefficient can be evaluated depending on the torque value.

Transformation of fine structure of lamellar pearlite under deformation of rail steel

The defective substructure of polycrystalline bodies causes substructural hardening and mechanical properties. Perlite, which is the main structural component of rails, undergoes a significant transformation during deformation, which is accompanied by a number of processes. In this paper, the methods of modern physical materials science were used to study and analyze the defective substructure of perlite of lamellar morphology and the properties of rail steel subjected to destruction under deformation conditions by single-axis stretching of flat samples. It was established that the ultimate strength varies from 1247 to 1335 MPa, and the relative deformation to failure – from 0.69 to 0.75. The formation of three zones of the fracture surface was observed: fibrous, radial and shear zones. Their shape and sizes were analyzed. Deformation of rail steel is accompanied by destruction of cementite plates of perlite colonies and repeated release of nanoscale particles of tertiary cementite approximately 8.3 nm in size in the volume of ferrite plates. The main mechanisms of destruction of cementite plates are cutting and dissolution. The dislocation substructure is represented by a chaotic distribution of dislocations and their clusters. The scalar density of dislocations in ferrite increases from 3.2·1010 cm–2 in the initial state to 7.9·1010 cm–2 when it is destroyed. Deformation is accompanied by formation of internal stress fields, manifested in the form of bending extinction contours. The sources of stress fields are the interface of cementite and ferrite plates, as well as grain boundaries. Fragmentation of ferrite and cementite plates was revealed. The average size of cementite fragments is 9.3 nm. In fracture zone of the rail steel sample, rotation of perlite grains was noted, indicating the presence of a rotational mode of deformation. Electron microscopic images of cementite plates show a change in the contrast, which may be associated with the formation of Cottrell’s atmospheres.

Multiscale structure of the gravitational wave signal from GW150914 based on the non-extensivity q-triplet

We study the first gravitational wave, GW150914, detected by advanced LIGO and constructed from the data of measurement of strain relative deformation of the fabric of spacetime. We show that the time series from the gravitational wave obeys Tsallis' q-Gaussian distribution as a probability density and its dynamics evolves from the three associated Tsallis' indexes named q-triplet. This fact strongly suggests that these black hole merger systems behave in a non-extensive manner. Furthermore, our results point out that the entropic indexes obtained as a function of frequency are useful statistical parameters to determine the dominant frequency when black hole coalescence is achieved.

Comprehensive study of the rheological status and intensity of oxidative stress during the progression of type 2 diabetes mellitus to prevent its complications.

Prevention of Type 2 diabetes mellitus (T2DM) requires a modifying effect on the pathological processes inducing the β-cell dysfunction. the comprehensive study of the violation of rheological parameters in patients with different stages of diabetes and identification of possible links between these alterations with the intensity of the oxidative stress in the patient's body. 60 patients with IR, prediabetes, T2DM and healthy volunteers were included. Full range of the rheological parameters of the patients' blood - the indicators of erythrocytes aggregation index (EAI), the relative deformability of the erythrocytes membranes (ERDI), blood plasma viscosity (BPV), and oxidative stress intensity (OSI) were examined. In patients with insulin resistance (IR), prediabetes, and T2DM the ERDI was statistically significantly lower and BPV - higher compared to control; a significant increase in EAI was detected in the patient group with prediabetes and T2DM compared to the control. The level of rheological disorders in patients increases with the increase of the level of carbohydrate metabolism disorders and intensity of oxidative stress and reaches a maximum during manifested diabetes. Diagnosis of hemorheological disorders and OSI in T2DM can serve as an early marker of target organ damage possibility.

PRACTICAL MODEL AND EXAMPLE OF A SQUARE REINFORCED CONCRETE STRUCTURE AT THE TORSION WITH BENDING

Statement of the problem. Development of a practical calculation model of reinforced concrete structures in torsion with bending of square cross-sections, most fully reflecting the features of the actual work of the structures. Results. The bearing capacity criterion from the intensity of the limit deformations and projection diagrams of complex elastoplastic tensors of compressed concrete in the calculation model of reinforced concrete structures under the joint action of forces for the constructed bilinear spatial crack is obtained. The reactions from the deformation effect of concrete and reinforcement in a crack were determined using the deformation effect and a dual-console element. The hypothesis of relative angular deformations for deplanation and gradients in the fracture was proposed. Here crack opening is the accumulation of relative concentrated mutual displacements of reinforcement and concrete. Conclusions. In the spatial section, the limit deformations were obtained by projecting the diagram of complex elastoplastic tensors of compressed concrete. The internal stresses from the deformation effects of concrete and reinforcement in the crack were found. The article includes an important algorithm and numerical example.

Modeling and Testing of a Stretchy Piezoelectric-Based Tactile Sensor

Present-day commercial tactile sensors for motion monitoring show poor water-absorbency, air-permeability, dynamic and flexibility, thus, prohibitive in wearable tech. To compensate for this restriction, this paper is concerned with the development and modeling of a stretchy arch-like tactile sensor for detecting signals in motion of a contact tissue. The main objective of this study is to design and model a piezoelectric sensor capable of measuring both obvious and weak movement state of contact tissue. The prototype sensor consists of three elastic layers and a combined arch. The cylindrical layer is made of micromachined resilient rubber can be used in noise reduction and shape-preserving property. The middle layer with a U-like structure that is built by high elasticity silica gel. The bottom layer is made of hyperelastomer with fence-like structure serving as a substrate and possessing hypo-allergenic and breathability function. Detecting the sensed objects athletic qualities is based on the relative deformation of contact object on the stretchy arch-like element. The PVDF film is embedded on the arched base plate and then sandwiched between the two electrodes to measure the force applied on the sensor. Mathematical algorithms and three-dimensional finite element modeling are used to analyze the performance of the designed system. The experimental results are very promising and proving the capability of the stretchy tactile sensor for haptic sensing and dynamic motion detection.

Development of a Generic Numerical Transtibial Model for Limb–Prosthesis System Evaluation

The well-established finite element method (FEM) has been used successfully to evaluate and develop medical devices for lower-limb prosthetics over recent decades. Most numerical models are based on a specific 3D geometry, which, although allowing for an accurate analysis of a specific case, may differ significantly from the target group that is often geometrically closer to the average residual limb. In order to address this issue, a generic numerical transtibial model was developed with the corresponding definitive socket and silicone liner. Three load cases were performed to analyse the applicability of the model: donning, single-leg stance, and the static P5 test according to ISO 10328. While the first two cases were used commonly in previous studies, the ISO test was only used in physical tests and not in a numerical environment. The results of the simulations in terms of contact pressure, as well as the relative deformation of the socket, fit into the range reported in the literature for similar boundary conditions, thus verifying the model in biomechanical terms. The generic transtibial model serves as a numerical tool for the relative comparison of different socket-liner designs prior to the fabrication, providing insights into results that are otherwise difficult to obtain.

Displacement incompatibility shape functions between masonry infill wall panels and reinforced concrete frames

During an earthquake, the detachment and local interaction between infill wall panels and surrounding frame can occur, potentially leading to significant local damage to both structural and non-structural elements, if not global collapse. Yet, a procedure to assess the relative deformation mechanism in terms of detachment shape and values, rather than, and in addition to, the diagonal compression strut mechanism and associated internal panel strain and stress path, is still missing in the literature. Therefore, in this paper the concept of shape functions is proposed and adopted to assess the seismic displacement incompatibility between infill walls and the surrounding frame structure. A parametric study on different typologies of infilled frames is developed to investigate the key parameters affecting the infill-frame detachment. The proposed concept of shape functions can support the design/retrofit of improved construction details, such as shear keys and/or steel dowels, in view of either decoupling or strengthening retrofit/repair strategies. Moreover, as infill-frame detachment can lead to damage to energy enhancement rehabilitation solutions, such as external thermal insulation systems, which are becoming more common nowadays in view of the international target towards a significant reduction of energy consumption and CO2 emission, it is suggested to implement the proposed displacement-compatible design check to assess and detail for adequate displacement capacity.

On the symplectic structure deformations related to the Monge–Ampère equation on the Kähler manifoldP2(ℂ)

UDC 517.9 We analyze the cohomology structure of the fundamental two-form deformation related to a modified Monge–Ampère type on the complex Kähler manifoldP2(ℂ). Based on the Levi-Civita connection and the related vector-field deformation of the fundamental two-form, we construct a hierarchy of bilinear symmetric forms on the tangent bundle of the K\"{a}hler manifoldP2(ℂ),that generate Hermitian metrics on it and corresponding solutions to the Monge–Ampère-type equation. The classical fundamental two-form construction on the complex Kähler manifoldP2(ℂ)is generalized and the related metric deformations are discussed.

Evaluation of Real-Time Perception of Deformation State of Host Rocks in Coal Mine Roadways in Dusty Environment

Intelligent mining needs to achieve real-time acquisition of surrounding rock deformation data of roadways and analysis and provide technical support for intelligent mining construction. To solve problems such as significant error, information lag, and low acquisition frequency of surrounding rock monitoring technology at the current stage, a perception method, RSBV of roadway deformation situation, based on binocular vision is proposed, which realizes the dynamic, accurate real-time acquisition of host rocks’ relative deformation in a dusky environment. The low illumination image enhancement method is used to preprocess original images, which reduces the impact of low illumination and high dust; the K-medoids algorithm segments the target image, and the SIFT algorithm extracts feature points from the ROI (region of interest). The influence of eliminating background images on the feature point extraction is revealed, and the efficiency of feature extraction is improved; the method of SIFT feature-matching with epipolar constraints is studied, which improves the accuracy and speed of feature points. The roadway deformation characteristics are analyzed, and the reflective target is used as the monitoring point. A roadway deformation acquisition and analysis platform based on binocular vision is built in a dim environment. Zhang’s method is selected to calibrate the camera parameters, and stereo rectification is carried out for the target motion image. The adaptability of the RSBV method to different surrounding rock deformation scales is studied and compared with the measurement results of the SGBM algorithm. The results show that the error of the RSBV method is controlled within 1.6%, which is 2.88% lower than the average error of the SGBM algorithm. The average time for processing a group of binocular images is 1.87 s, which is only 20% of the SGBM algorithm. The research result provides a reliable theoretical basis for the real-time and accurate evaluation of the surrounding rock deformation mechanism.

Relationship of Population Attributes of a Dominant Macrofaunal Species with Environmental Conditions in a Eutrophic Estuary (Guanabara Bay, Brazil)

Hydrobioid gastropods are abundant in coastal systems and ecologically important for ecosystem functioning. We aimed to unravel the relationship between usual and stress-related population attributes of the dominant macrofaunal species Heleobia australis with indicators of environmental quality and coastal pollution. Using Guanabara Bay (GB, Brazil) as a model of a multi-impacted coastal system, our hypothesis is that increased amounts of rainfall during the warm season reduce the bay’s environmental quality and induce shifts in snail population attributes. A suite of environmental variables, population attributes, and sediment quality descriptors was assessed by combining field and laboratory evaluations with literature compilation. Results indicate high organic pollution levels with environmental degradation and reinforce GB status as a severely contaminated system. Some environmental conditions can be applied as seasonal predictors of changes in warm-rainy (rainfall and salinity), intermediate (silicate), and cold-dry seasons (nitrite and nitrate). Three selected usual population attributes (snail density, fecundity, and recruitment) were not affected by changes in environmental conditions, but significant effects were detected on two stress-related attributes (relative penis length index and shell deformity). For the first time, shell deformity was recorded in H. australis snails. Low variation in usual population attributes highlight the high tolerance of H. australis to shifts in environmental conditions.

Effects of Running Intensity on Forefoot Plantar Pressure Elevation

Running had been known producing a posterior muscle tightness in lower extremity, particularly calf muscles, resulting in a relative equinus deformity. Numerous study reported the association between equinus deformity and foot pain, partially due to the increased plantar pressure of forefoot. This study was directed to find a relation between running intensity and increased forefoot plantar pressure. Subjects were divided into two groups according to running intensity as classified as runner or non-runner. Forefoot plantar pressures data were obtained using a foot imprinter and analyzed into numerical values. Ankle maximum dorsiflexion was also examined in an extended knee to detect the calf tightness. Mean forefoot plantar pressure value was Grau 2.89 (range 2-4) in runner group, and Grau 2.15 (range 1-4) in non-runner group (p=0.004). Ankle maximum dorsiflexion was also limited in runner group (16.05±1.98⁰) compared with 19.30±1.38⁰ in non-runner group (p&lt;0.001). There was an association found between running intensity and plantar pressure elevation. Considering the potential damaging effects to the foot, it is recommended for runners or treating physician to look into this problem as well as to make sure that regular calf stretching is advocated.