Magnitude Of Deformation Research Articles

High‐speed escape jumps in haptophytes: Mechanism and triggering fluid signal

AbstractSome planktonic organisms can remotely sense and evade predators by powerful escape jumps. Remote perception typically happens through the fluid disturbance generated by the approaching predator or its feeding current. In copepods and ciliates with mechanosensors, the perception and jump mechanisms are well understood. But how some flagellates perceive the fluid disturbance and achieve similar relative speeds with only two flagella is less explored. Here, we examined the ability of three haptophytes, Chrysochromulina simplex, Prymnesium polylepis, and Prymnesium parvum, to sense and evade the fluid disturbance generated by the feeding current of a copepod nauplius. Chrysochromulina simplex has a long haptonema (14 cell diameters), while the haptonema of the two other species are shorter (1 and 0.5 cell diameters). Only C. simplex responded to the fluid disturbance by fleeing at high speeds. The jump mechanism consists of two phases: the rapid coiling of the haptonema that pulls the cell about two cell diameters in the direction of the haptonema, followed by flagellar reversal and high‐speed swimming (70 cell lengths per second) in the opposite direction. We rationalize cell displacements and escape speeds from haptonema and flagellar kinematics and fluid dynamics. Using a microfluidic channel, we demonstrate that the component of the fluid signal that triggers the jumps is the maximum deformation rate rather than the magnitude of deformation. High‐speed escape jumps may be an avoidance mechanism evolved by haptophytes with long and coiling haptonema, while species with shorter haptonema may use other defense mechanisms, such as stealth and toxicity.

Computational design of 4D printed shape morphing lattices undergoing large deformation

Abstract In 4D Printing, active materials are embedded in structures such that the application of an external stimulus, usually coming from the environment, results in a structural response. To design structures that achieve a targeted shape change for a defined stimulus, also known as shape morphing, the material distribution and structure needs to be tuned. However, the computational design of such material distributions and structures is a challenging task and remains, despite recent advances, unable to fully leverage the entire design freedom offered by state-of-the-art 4D printing technology. Notable gaps concern the handling of large and complex deformations, the high computational cost, and the exploration of the design space by the generation of alternative solutions. In this article, a method is presented to fill this gap. First, an artificial neural net is trained that represents a deformation map that occurs during actuation. Then, a shape morphing truss is designed that achieves this deformation during actuation. The method is used to solve four shape morphing problems, where superior capabilities are demonstrated in terms of magnitude and complexity of deformations that can be handled, efficient generation of alternative solutions and versatility. Due to these capabilities, the method enables exploration of the full potential of 4D printing technology to create stimuli-responsive, multifunctional structures.

Deformation Monitoring and Analysis of Baige Landslide (China) Based on the Fusion Monitoring of Multi-Orbit Time-Series InSAR Technology.

Due to the limitations inherent in SAR satellite imaging modes, utilizing time-series InSAR technology to process single-orbit satellite image data typically only yields one-dimensional deformation information along the LOS direction. This constraint impedes a comprehensive representation of the true surface deformation of landslides. Consequently, in this paper, after the SBAS-InSAR and PS-InSAR processing of the 30-view ascending and 30-view descending orbit images of the Sentinel-1A satellite, based on the imaging geometric relationship of the SAR satellite, we propose a novel computational method of fusing ascending and descending orbital LOS-direction time-series deformation to extract the landslide's downslope direction deformation of landslides. By applying this method to Baige landslide monitoring and integrating it with an improved tangential angle warning criterion, we classified the landslide's trailing edge into a high-speed, a uniform-speed, and a low-speed deformation region, with deformation magnitudes of 7~8 cm, 5~7 cm, and 3~4 cm, respectively. A comparative analysis with measured data for landslide deformation monitoring revealed that the average root mean square error between the fused landslide's downslope direction deformation and the measured data was a mere 3.62 mm. This represents a reduction of 56.9% and 57.5% in the average root mean square error compared to the single ascending and descending orbit LOS-direction time-series deformations, respectively, indicating higher monitoring accuracy. Finally, based on the analysis of landslide deformation and its inducing factors derived from the calculated time-series deformation results, it was determined that the precipitation, lithology of the strata, and ongoing geological activity are significant contributors to the sliding of the Baige land-slide. This method offers more comprehensive and accurate surface deformation information for dynamic landslide monitoring, aiding relevant departments in landslide surveillance and management, and providing technical recommendations for the fusion of multi-orbital satellite LOS-direction deformations to accurately reconstruct the true surface deformation of landslides.

Crack tip stress intensification in strain-induced crystallized elastomer

Natural rubber (NR) exhibits strain-induced crystallization (SIC), enhancing tearing strength and crack resistance. However, the reinforcement mechanism along with nonuniform strain around a crack tip remains unclear. We reveal the nonuniform stress field around a crack tip using the DIC-based deformation field data and a hyperelasticity approach. A hyperelastic strain energy density function (W) is derived to be able to replicate stress-strain data across various deformations, encompassing equal and unequal biaxial, uniaxial, and pure shear stretching. These data cover the full range and magnitude of deformations around the crack tip. SIC significantly impacts the singular behaviors of strain and stress near the crack tip, causing a pronounced stress increase and strain decrease within the SIC zone that extends up to approximately 100 μm away from the crack tip. This results in a distinct crossover in singularity power-law index between the SIC zone and the fully amorphous zone. With increasing crack opening, the stress upturn intensifies, and the crossover shifts away from the crack tip due to SIC zone enlargement and local crystallinity increase. These findings deepen our understanding of the physics of SIC near crack tips and its reinforcement mechanism in strain-induced crystallizable soft solid materials.

Clinical outcomes of primary total knee arthroplasty in non-syphilitic neuroarthropathy of the knee.

Total knee arthroplasty (TKA) in syphilitic neuroarthropathy using earlier implant designs was associated with poorer outcomes. Literature on TKA for non-syphilitic neuroarthropathy using modern contemporary prosthesis is scarce. We aim to analyse the clinical and radiological outcomes of TKA in neuropathic joints. A final cohort of 17 patients (21 knees) with the diagnosis of neuropathic joint undergoing primary TKA between January 2013 to January 2019 were included in the study. The preoperative ambulatory status, range of motion, type of prosthesis, level of constraint and any augmentation used were retrieved from medical records. Radiological evaluation includes Koshino's staging, the magnitude of deformity defined by the Hip-Knee-Ankle (HKA) angle, and any progressive loosening. Pre and postoperative functional scores were obtained by the Knee Society (KSS) and Knee Society Functional Score (KSS-F). Any complications or reoperation were noted till the final follow-up. Preoperative and follow-up functional scores, HKA and range of motion were compared using the paired Samples test. The mean follow-up was 40.2 months (range, 15 to 75 months). Preoperatively, according to the Koshino staging, five knees were in stage 3 (23.8%). The mean HKA angle in valgus knees was 23.60 (range, 11.10 to 42.50) and for the varus knees was 19.30 (range, 4.90 to 39.60). The prosthesis used were posterior stabilized in 7 knees (33.3%), varus-valgus constrained in five knees (23.8%) and a rotating hinge was required in nine knees (42.8%). Metaphyseal sleeves were used along with hinge prosthesis in six knees (28.6%). The mean arc of motion improved from 102.4 ± 22.7 degrees to 105.7 ± 15.5 degrees postoperatively (p = 0.27). The knee society and knee society functional scores improved from 23.3 ± 9.3 and 28.3 ± 12.2 preoperatively to 81.1 ± 5.4 and 80.4 ± 8.5 during the follow up respectively (p < 0.001). There were no progressive radiolucent lines in any knees at the final follow-up. One patient had intraoperative bony medial collateral ligament injury, one patient had deep vein thrombosis after five days from the index surgery and another had postoperative periprosthetic tibial shaft fracture. According to our study, the clinical outcomes of TKA for neuroarthropathy show significant improvement with the diagnosis of non-syphilitic neuroarthropathy, utilization of modern constrained prostheses, and early rehabilitation, at medium-term follow-up. Tibial and femoral stems are preferred for equal stress distribution and to prevent early loosening.

Identification of Potential Landslides in the Gaizi Valley Section of the Karakorum Highway Coupled with TS-InSAR and Landslide Susceptibility Analysis

Landslides have become a common global concern because of their widespread nature and destructive power. The Gaizi Valley section of the Karakorum Highway is located in an alpine mountainous area with a high degree of geological structure development, steep terrain, and severe regional soil erosion, and landslide disasters occur frequently along this section, which severely affects the smooth flow of traffic through the China-Pakistan Economic Corridor (CPEC). In this study, 118 views of Sentinel-1 ascending- and descending-orbit data of this highway section are collected, and two time-series interferometric synthetic aperture radar (TS-InSAR) methods, distributed scatter InSAR (DS-InSAR) and small baseline subset InSAR (SBAS-InSAR), are used to jointly determine the surface deformation in this section and identify unstable slopes from 2021 to 2023. Combining these data with data on sites of historical landslide hazards in this section from 1970 to 2020, we constructed 13 disaster-inducing factors affecting the occurrence of landslides as evaluation indices of susceptibility, carried out an evaluation of regional landslide susceptibility, and identified high-susceptibility unstable slopes (i.e., potential landslides). The results show that DS-InSAR and SBAS-InSAR have good agreement in terms of deformation distribution and deformation magnitude and that compared with single-orbit data, double-track SAR data can better identify unstable slopes in steep mountainous areas, providing a spatial advantage. The landslide susceptibility results show that the area under the curve (AUC) value of the artificial neural network (ANN) model (0.987) is larger than that of the logistic regression (LR) model (0.883) and that the ANN model has a higher classification accuracy than the LR model. A total of 116 unstable slopes were identified in the study, 14 of which were determined to be potential landslides after the landslide susceptibility results were combined with optical images and field surveys. These 14 potential landslides were mapped in detail, and the effects of regional natural disturbances (e.g., snowmelt) and anthropogenic disturbances (e.g., mining projects) on the identification of potential landslides using only SAR data were assessed. The results of this research can be directly applied to landslide hazard mitigation and prevention in the Gaizi Valley section of the Karakorum Highway. In addition, our proposed method can also be used to map potential landslides in other areas with the same complex topography and harsh environment.

No deceleration signs in the permafrost ground subsidence four years after the 2019 fire in Northwest Territories, Canada

Abstract The circum-arctic permafrost environment is often disturbed by wildfires but could also show resilience to these disturbances. However, the increased frequency and extent of wildfires, coupled with unprecedented hot weather, have introduced greater uncertainties in the post-fire permafrost dynamics. We need to address emerging questions, e.g., How will permafrost respond to the joint effect of hot anomalies and wildfires? To what extent will post-wildfire deformation evolve? How will permafrost resilience to wildfires vary? Utilizing Interferometric Synthetic Aperture Radar (InSAR) time series analysis, we investigated the post-wildfire ground deformation around a 2019 fire scar in the lower Mackenzie Valley, Northwest Territories, Canada, where dramatic heat anomalies and severe wildfires have been recorded in recent years. The resilience of permafrost to wildfires appears to be weakened by the continuous and rapid warming after the fire, as evidenced by the year-on-year acceleration in subsidence rates. Such acceleration was never reported by previous findings that typically observed deceleration in subsidence rates four to five years after wildfires. The deformation along the line of sight (LOS) of the satellite demonstrates significant permafrost degradation induced by wildfires and exacerbated by climate warming, and the cumulative subsidence was detected up to 25 cm in the LOS direction in the upland areas and up to 10 cm in the lowland areas four years after the fire. The difference in deformation magnitude could be attributed to local factors, including ground ice, topography, and vegetation. Our study highlights the increasingly severe threat to circum-arctic permafrost due to the combined effects of wildfires and extreme heat anomalies.

A stacking sequence optimization strategy for process‐induced deformation of multi‐layer thick asymmetric laminates

AbstractThe occurrence of process‐induced deformations of composites laminates is challenging for assembly accuracy and may lead to a service life reduction of parts. However, it can be obviously mitigated through different optimization strategies on the basis of the accurate curing process simulation. In this study, a stacking sequence optimization strategy is proposed and applied to multi‐layer thick asymmetric laminates. The shapes of deformed laminate plates are experimentally investigated in virtue of the three‐dimensional coordinate measuring machine. The thermo‐chemical–mechanical behaviors of plates are first verified through the comparisons of model predicted and experimental process‐induced deformations. Then the nonlinear control formula achieved through the regression model is proposed for the direct relationship between stacking sequences and process‐induced deformations. Finally, the required solutions are generated by solving the control formula. With the comparisons between the average deformations before and after optimizations, it is found that the magnitudes of deformations are significantly reduced, especially when the unoptimizated deformations are large.Highlights The thermo‐chemical–mechanical behavior can be described in the curing process simulation model. The deformed shapes of multi‐layer thick asymmetric laminate plates are measured by a three‐dimensional coordinate measuring machine. The stacking sequence optimization strategy is implemented by introducing a nonlinear control formula.

Inelastic fluid models with an objective stretch rate parameter

This paper presents an extension to the Generalized Newtonian Fluid (GNF) model, where the effects of different flow modes can be discerned. While existing GNF models have proven valuable in simulating processes like molding and extrusion, they often struggle to differentiate between distinct flow modes such as planar extension and simple shear. To address this challenge, we propose a modified GNF model that integrates an objective flow-type parameter, aiming to refine flow characterization. Emphasis is placed on defining the flow-type parameter to be able to transcend viscometric flows, remain frame-indifferent, quantify deformation magnitude, and differentiate between diverse flow modes. Inspired by the new advances in vortex identification in turbulent flow, we introduce a new stretch rate tensor and a new stretch rate parameter that are derived from the real Schur form of the objective velocity gradient tensor. These elements are embedded into the constitutive modeling of non-Newtonian fluid flow. The resulting model is employed to fit polymer melt data from the literature, demonstrating excellent fitting to combined shear and extension data. The basic model uses 5 to 6 parameters for data fitting, and further enhancement may be achieved by incorporating other extracted information of the stretch rate tensor.

Comprehensive evaluation of right ventricular function in patients with acute pulmonary embolism

Objective. To study indices of right ventricular (RV) longitudinal deformation at transthoracic echocardiography (TTE) in patients with acute pulmonary embolism (APE), to determine their threshold values; to study indices of right ventricular-arterial coupling (RVAC) in patients with APE, to determine their threshold values.Methods. We examined 34 patients with acute massive and submassive pulmonary embolism. The diagnosis was made on the basis of computed-tomography pulmonary angiogram. The mean age was 61 ±13 years. Of these, 16 were women (47,1%) and 18 were men (52,9%). As a control group, 30 healthy individuals were examined: 14 males and 16 females. The mean age of the healthy individuals was 39±9,8 years. Echocardiography was performed on Vivid E95 (GE HealthCare, USA) with data postprocessing on EchoPak workstation. The indices of right ventricular (RV) systolic and diastolic function, the magnitude of global longitudinal deformation of the right ventricle (GLS RV) and longitudinal deformation of the right ventricular free wall (RVFWLS) were studied using two-dimensional speckle-tracking echocardiography. We studied indices of right ventricular-arterial coupling (RVAC). We determined the relationship of longitudinal deformation of RV and RVAC with other indices of its systolic function. Results. Mean values of traditional parameters of RV contractile function were within normal limits, whereas mean values of longitudinal strain in APE were significantly lower than normal. There was also a significant decrease ( P &lt; 0,0001) of all measured parameters of right ventricular-arterial coupling in patients with APE in comparison with the control group.Conclusions. When longitudinal deformation parameters are included in the criteria of RV dysfunction in APE, its detectability increases from 26,47% to 61,77%. The revealed decrease of right ventricular-arterial coupling parameters in APE indicates a more frequent disturbance of the connection between RV and the small circle of blood circulation

Large deformation problems arising from deep excavation in silt strata: A case study in Shenzhen, China

Deep excavations in silt strata can lead to large deformation problems, posing risks to both the excavation and adjacent structures. This study combines field monitoring with numerical simulation to investigate the underlying mechanisms and key aspects associated with large deformation problems induced by deep excavation in silt strata in Shenzhen, China. The monitoring results reveal that, due to the weak property and creep effect of the silt strata, the maximum wall deflection in the first excavated section (Section 1) exceeds its controlled value at more than 93% of measurement points, reaching a peak value of 137.46 mm. Notably, the deformation exhibits prolonged development characteristics, with the diaphragm wall deflections contributing to 39% of the overall deformation magnitude during the construction of the base slab. Subsequently, numerical simulations are carried out to analyze and assess the primary factors influencing excavation-induced deformations, following the observation of large deformations. The simulations indicate that the low strength of the silt soil is a pivotal factor that results in significant deformations. Furthermore, the flexural stiffness of the diaphragm walls exerts a notable influence on the development of deformations. To address these concerns, an optimization study of potential treatment measures was performed during the subsequent excavation of Section 2. The combined treatment approach, which comprises the reinforcement of the silt layer within the excavation and the increase in the thickness of the diaphragm walls, has been demonstrated to offer an economically superior solution for the handling of thick silt strata. This approach has the effect of reducing the lateral wall displacement by 83.1% and the ground settlement by 70.8%, thereby ensuring the safe construction of the deep excavation.

Severe Rigid Scoliosis Deformity Correction Using Extended Posterior Release and Instrumentation: A Retrospective Study.

Sever rigid scoliotic deformity (magnitude of the curve >80° and <25% correction on bending film) correction is a great challenge to spine surgeons. Severe scoliosis when untreated or not treated properly, may lead to severe complications due to curve progression. The aim of operative management is to achieve significant correction of sagittal, coronal, and rotational deformity to avoid neurodeficit, maintain sagittal balance, and improve cardiopulmonary function. In this retrospective study, eight patients with severe rigid scoliosis who underwent through single-staged extended posterior release and spinal fusion between March 2022 and November 2023. The surgical procedures were the excision of the posterior ligament and spinous process, laminectomy, excision of ligament flavum, facetectomy, and posterior spinal fusion utilizing pedicle screws, rods, and sub-laminar wires. Patients were evaluated radiologically using posteroanterior and lateral X-rays of the whole spine and computed tomography scans. Demographic data, pre- and post-operative cobbs angle, osteotomized segment, instrumentation segments, blood loss, operation duration, follow-up duration, and complications were recorded. Pre-operative mean cobbs angle was 94.1° (range 83-110°) and post-operative mean cobbs angle was 33.3° (range 28-42°) with 64.6% scoliosis correction. The mean estimated blood loss was 517 mL (range 300-580 mL). The mean operation duration was 272.5 min (210-340 min). Mean spinal fixation fusion segments were 11.1 (range 8-14). No major complications were noted. Our study concluded that extended posterior-only release, facetectomy, and posterior spinal fusion by utilizing pedicle screws and pre-contoured rods significantly corrected severe and rigid scoliosis with a high correction rate and avoid complications of anterior release. Hence, we can achieve remarkable correction in rigid scoliosis using the proper choice of levels, proper implant, and extended posterior release.

Predicting Seasonal Deformation Using InSAR and Machine Learning in the Permafrost Regions of the Yangtze River Source Region

AbstractQuantifying seasonal deformation is essential for accurately determining the thickness of the active layer and the distribution of water content within it, providing insights into the freeze‐thaw dynamics of permafrost environments and their sensitivity to climate change. Due to the limited hydraulic conductivity of the underlying permafrost, the freeze‐thaw processes are largely confined to the active layer, allowing for predictable seasonal deformations. This study employed Independent Component Analysis to isolate large‐scale seasonal deformation from Interferometric Synthetic Aperture Radar (InSAR) measurements taken from 2016 to 2020 in the Yangtze River Source Region (YRSR) of the Qinghai‐Tibet Plateau (QTP), covering 18,500 km2. We developed dedicated machine learning (ML) models that integrate these InSAR‐derived measurements with various environmental proxies. By applying these models to the YRSR, we generated a comprehensive, full‐coverage deformation map for permafrost terrains, achieving an R2 value of 0.91 and an Root Mean Squared Error of approximately 0.5 cm, thus confirming the model's strong predictability of seasonal deformation in permafrost regions. Deformation magnitude varied from less than 1 cm to over 10 cm. Our analysis suggests that terrain attributes, influenced by climate and soil conditions, are the primary factors driving these deformations. This research provides valuable insights into quantifying permafrost‐related seasonal deformation across expansive and rural landscapes. It also aids in assessing subsurface hydrological processes and the resilience and vulnerability of permafrost. The developed ML algorithm, with access to precise environmental data, is capable of forecasting seasonal deformations across the entire QTP and potentially throughout the Arctic.

Clinical, Radiographic, and Biomechanical Evaluation of the Upper Extremity in Patients with Osteogenesis Imperfecta.

Introduction: Osteogenesis imperfecta (OI) is a hereditary disorder primarily caused by mutations in type I collagen genes, resulting in bone fragility, deformities, and functional limitations. Studies on upper extremity deformities and associated functional impairments in OI are limited. This cross-sectional study aimed to evaluate upper extremity deformities and functional outcomes in OI. Methods: We included patients regardless of their OI subtypes with a minimum age of 7 years. Radiographic analysis of radial head dislocation, ossification of the interosseous membrane, and/or radioulnar synostosis of the forearm were performed, and deformity was categorized as mild, moderate, or severe. Clinical evaluation was performed using the Quick Disabilities of Arm, Shoulder, and Hand (qDASH) questionnaire and shoulder-elbow-wrist range of motion (ROM). Three-dimensional motion analysis of the upper limb was conducted using the Southampton Hand Assessment Procedure (SHAP). The SHAP quantifies execution time through the Linear Index of Function (LIF) and assesses the underlying joint kinematics using the Arm Profile Score (APS). Additionally, the maximum active Range of Motion (aRoM) was measured. Results: Fourteen patients aged 8 to 73 were included. Radiographic findings revealed diverse deformities, including radial head dislocation, interosseous membrane ossification, and radioulnar synostosis. Six patients had mild, six moderate, and two severe deformities of the upper extremity. Severe deformities and radial head dislocation correlated with compromised ROM and worse qDASH scores. The qDASH score ranged from 0 to 37.5 (mean 11.7). APS was increased, and LIF was reduced in OI-affected persons compared with non-affected peers. APS and LIF also varied depending on the severity of bony deformities. aRoM was remarkably reduced for pro-supination. Conclusion: Patients with OI showed variable functional impairment from almost none to severe during daily life activities, mainly depending on the magnitude of deformity in the upper extremity. Larger multicenter studies are needed to confirm the results of this heterogeneous cohort. Level of evidence: Retrospective clinical study; Level IV.

Использование новых видов технологической оснастки при изготовлении нежестких плоскостных алюминиевых деталей методом волновых технологий

It has been suggested that wave technologies in non-rigid plane parts production should be used with the introduction of ultrasonic range vibrations into the shaping zone in combination with technological equipment, i.e. it is- a zero-base system. The traditional technique used in domestic enterprises implies a high probability of out-of-flat conditions and deformations due to the influence of technological residual stresses (TRS) in the process of stock removal or force stresses under plastic deformation of the part when fixing blanks. Using modern universal software systems such as Simulia Abaqus, ANSYS, etc., it was possible to determine the magnitude of deformations, aligment errors caused by residual stresses. The data obtained were used to calculate rational ways for fixing some typical non-rigid plane aluminum blanks on a technological equipment - a zero-based system of German production SCHUNKVERO–SAviation (VSA). The research was aimed at determining the manufacturability for the use of such equipment when making a particular non-rigid blank made of aluminum alloys and finding the most optimal way of its fixing. The estimated values of the TRS were determined by mechanical and X-ray methods. The calculations were performed using real parts of aircraft equipment of the "beam" type and blanks made of aluminum rolled products. The proposed method for determining the maximum amount of deformation of the workpiece under machining is applicable to the most optimal placement of the support and clamping modules of the zero-based system (VSA). In combination with a certain strategy of wave mechanical processing, it makes a practically complete compensation for deformations possible and allows obtaining a suitable product from the first presentation without performing an additional correction operation.

Comparative analysis of surgical treatment results for osteoporotic burst fractures of thoracolumbar vertebral bodies

Introduction Surgical methods for osteoporotic burst vertebral body fracture repair have their advantages and shortcomings. The use of circumferential stabilization and corrective vertebrotomies in elderly patients is highly invasive and carries great surgical risk. On the other hand, minimally invasive methods lead to recurrence of the deformity. Thus, in the treatment of patients with such pathology, it is necessary to choose a surgical method that allows achieving optimal results.Purpose of the work was to compare the results of surgical treatment for osteoporotic burst fractures in thoracolumbar vertebral bodies using the developed method and methods of circular and hybrid stabilization based on clinical and radiological criteria.Materials and methods The study was retrospective. Three groups of patients were formed according to the type of surgical intervention. Inclusion criteria were patients with primary osteoporosis who did not receive osteotropic therapy before surgery, with osteoporotic fractures (type OF3 and OF4) of the vertebral bodies of the thoracolumbar location (Th10–L2). The follow-up period was 12 months. The following criteria were assessed: the amount of kyphosis correction (according to the Cobb method), the amount of residual postoperative kyphotic deformity, as well as its recurrence in the long-term postoperative period; sagittal balance of the torso (Barrey index), subjective evaluation of the patient’s condition (VAS). Quality of life assessment was not performed.Results There were no statistically significant differences in the dynamics of sagittal balance during the follow-up period between the groups (p &gt; 0.99). There was no difference between groups in clinical outcomes (VAS) at follow-up (p &gt; 0.05). A statistically significant difference in the magnitude of kyphotic deformity and its correction in the specified postoperative periods was revealed between the hybrid fixation groups and the corrective vertebrotomy group. No difference was found with the circular stabilization group.Discussion Due to the high risks of poor outcomes of anterior spinal fusion, in particular, implant subsidence, to avoid anterior spinal fusion, we used a method of focal kyphosis correction and posterior spinal fusion with autologous bone. The method proposed by the authors for the correction of focal kyphotic deformity in the treatment of patients with osteoporotic burst fractures of the vertebral bodies combines satisfactory correction of focal kyphosis with minimal surgical invasiveness, which reduces the risks of complications and poor outcomes. The proposed method may also be combined with hybrid fixation.Conclusion The developed method for focal kyphotic deformity correction in the treatment of osteoporotic burst fractures of vertebral bodies provides satisfactory correction of focal kyphosis, reduces the risks of complications and poor outcomes in comparison with circular and hybrid stabilization.

Measurement of safety state of cross-jointed segmental lining based on system performance index

The correlation between convergence deformation and the safety state of a cross-jointed segmental lining is investigated and clarified. The limitations of convergence deformation as a measuring scale is explored also. Firstly, an analytical algorithm (known as the relative stiffness method, RSM) is developed and verified for tracing the mechanical response of a cross-jointed segmental lining in failure history. Then, an explicit mapping relationship between convergence deformation and the causal factors is established using the RSM. Finally, the root causes of the limitations in using convergence deformation as a scale to evaluate tunnel safety state are discussed, and an alternative quantity, the system performance index (SPI), is proposed. It shows that: (1) The convergence deformation consists of three components induced by segment bending, elastic joint rotation, and joint stiffness attenuating, respectively. The deformation induced by attenuating joint stiffness is dependent on the failure index of segment joints and provides crucial information about the load-bearing state of the segment joints; (2) The components of elastic joint rotation and joint stiffness attenuating are significantly affected by the contact stiffness of the segment joint interface, including the physical and mechanical properties of the packing material. The magnitudes of convergence deformation and its components are not suitable for use as a quantitative scale to evaluate the safety state of the lining due to their inherent drawbacks; (3) The proposed dimensionless variable SPI can eliminate the influence of packing material on the safety state of the segment lining and reflect the comprehensive influence of the failure indexes of the segment joints.

Heat transfer deformation test and model of coal during LN2 cyclic freezing and thawing process

Exploring the temperature response and deformation characteristics of coal during the freeze–thaw process is crucial for maintaining coal seam stability under liquid nitrogen (LN2) treatment and enhancing gas extraction efficiency. This study investigates the temperature diffusion and deformation characteristics of coal during LN2 cyclic freeze–thaw processes, using saturated and dry anthracite samples. Real-time monitoring of the freeze–thaw characteristics of the anthracite samples was conducted using temperature and strain detectors to quantitatively analyze the evolution of coal temperature and strain. Additionally, a nuclear magnetic resonance (NMR) testing system was used to monitor the pore evolution characteristics of the coal before and after LN2 treatment. The results indicate: After LN2 cyclic freeze–thaw, the internal pores of the saturated samples were highly developed, and fracture connectivity was enhanced, whereas the pores in the dry samples significantly decreased, leading to a sharp reduction in overall connectivity. The cooling and heating rates of the saturated samples were higher than those of the dry samples, both exhibiting exponential trends. This variation is primarily due to the phase change of pore water and the formation and expansion of the internal fracture network within the coal. The deformation magnitude of both sample types showed an overall exponential decline, with the saturated samples exhibiting higher deformation magnitudes than the dry samples. The presence of fracture water not only accelerates coal deterioration during the freeze–thaw process but also enhances coal cementation, maintaining deformation stability. Furthermore, this paper derives a temperature-strain coupling model for coal subjected to LN2 F-T cycles, aiming to provide a reference for understanding the freeze–thaw damage mechanism of coal and the practical application of LN2 fracturing.

Influence of welding sequences and boundary conditions on residual stress and residual deformation in DH36 steel T-joint fillet welds

This paper aims to investigate the influence of welding sequences and boundary conditions on welding-induced residual stress and residual deformation of DH36 steel T-joint fillet welds through experimental and numerical methods. A series of typical experiments of successive and simultaneous double-sided welding conditions are conducted to explore both the magnitude and distribution of temperature field, residual stress and residual deformation. Meanwhile, thermal elastic-plastic finite element analysis based on a double ellipsoidal heat source model is performed to investigate the heat transfer and deformation mechanism during the welding process. The influencing factors are further explored to determine and quantify the residual stress and residual deformation induced by different welding sequences and boundary conditions. There is generally well agreement between the experimental and numerical results in terms of temperature field, residual stress, residual deformation and molten pool morphology. The results show that the welding sequences have an important influence on the magnitude and distribution of residual stress and residual deformation. Continuous simultaneous double-sided welding can significantly reduce residual stress and residual deformation to obtain better-quality welds. Boundary conditions have a significant effect on the distribution and magnitude of residual deformation and little effects on residual stress. Tightening the ends of the flange plate with bolts during the welding process can significantly reduce the deformation.

Effect of drawing deformation on microstructure and mechanical properties of Fe-Cr-Co-W alloy

The mechanical properties of strain gauge wire are intricately linked to the process of drawing deformation, playing a pivotal role in the performance of associated sensors. This study delves into the impact of varying degrees of drawing deformation on both the mechanical properties and microstructure of FeCrCoW strain gauge alloy wires. Through a comprehensive analysis of tensile testing, XRD, SEM, and TEM, a detailed and systematic exploration was conducted on the influence of different tensile deformation variables on the mechanical properties of alloys, while also exploring fracture mechanisms. The research results showed that the yield strength and fracture strength of FeCrCoW alloy gradually increase with the tensile deformation raising, while the fracture strain and work hardening rate gradually decrease. Advanced TEM investigations have elucidated that the phenomenon of grain refinement and the concomitant rise in dislocation density within the alloy escalates markedly with escalating levels of drawing deformation. This enhanced microstructural evolution is posited as the principal driver linking the alloy's mechanical properties to the magnitude of deformation experienced. Concurrently, the dynamic interplay between tungsten (W)-rich nanoparticles and the alloy's dislocations during the drawing process is identified as a significant contributor to the observed alterations in mechanical behavior. The synergistic effects of these microstructural changes are likely responsible for the nuanced shifts in the alloy's mechanical attributes.