Load Transmission Research Articles

The Migration Pattern of a Short-Tapered Femoral Stem Correlates with the Occurrence of Cortical Hypertrophies: A 10-Year Longitudinal Study Using Ein Bild Röntgen Analyse-Femoral Component Analysis.

Background: Shorter hip stems have shown promising mid-term results but lack long-term data. High rates of distal cortical hypertrophy (CH) have been described, suggesting a more diaphyseal load transmission. This study aimed to determine patient-specific and surgery-related factors influencing CH and their impact on 10-year outcomes. Methods: It included 100 consecutive total hip arthroplasties (THAs) using the Fitmore stem (Zimmer, Warsaw, Indiana), with clinical and radiographic follow-ups at 1, 2, 5, and at least 10 years post-surgery. Results: No revisions were performed due to aseptic loosening after a mean of 11.6 years (range: 10-13.5 years). CH was observed in 26% of hips, primarily in Gruen zones 3 and 5. There was no significant difference in the Harris Hip Score between patients with and without CH. Larger stem sizes and greater axial subsidence significantly correlated with CH occurrence (OD 1.80, (1.13-1.92), p = 0.004; OD 1.47, (1.04-2.08), p = 0.028). The Fitmore stem demonstrated excellent survival rates and favorable outcomes over 10 years. Conclusions: Despite a lower CH rate compared to other studies, significant correlations with stem size and subsidence were identified. This study underscores the importance of patient selection and achieving high primary stability to maintain the metaphyseal anchoring concept.

Proximal cementation of a collarless polished tapered hip stem: biomechanical analysis using a validated finite element model.

Total hip replacement (THR) with cemented stem is a common procedure for patients with hip osteoarthritis. When primary THR fails, removal of the cement is problematic and poses challenges during revision surgeries. The possibility of proximal partial cementing of the hip stem was explored to mitigate the problem. 3D finite element analysis was performed to investigate the feasibility of reduced cement length for effective implant fixation and load transmission. Three levels of cement reduction (40mm, 80mm, and 100mm) in the femoral stem were evaluated. All models were assigned loadings of peak forces acting on the femur during walking and stair climbing. The experimental and predicted max/min principal bone strains were fitted into regression models and showed good correlations. FE results indicated stress increment in the femoral bone, stem, and cement due to cement reduction. A notable increase of bone stress was observed with large cement reduction of 80-100mm, particularly in Gruen zones 3 and 5 during walking and Gruen zones 3 and 6 during stair climbing. The increase of cement stresses could be limited to 11% with a cement reduction of 40mm. The findings suggested that a 40-mm cement reduction in hip stem fixation was desirable to avoid unwanted complications after cemented THR.

Epidemic dynamics edge caching strategy for 6G networks

By caching popular content on edge servers closer to users to respond to users’ content requests in 6G networks, the transmission load of backhaul links can be reduced. However, the time-varying characteristics of content prevalence leads to the issue that the cache content may not match the user’s needs, resulting in a decrease in cache success ratio. To solve these issues, we proposed a cache distribution strategy based on epidemic dynamics (CDSED) for 6G edge network. First, a 6G edge caching content model (6G ECCM) is constructed to establish the process of cache content propagation among users as an infectious disease propagation process, analyze the distribution of users’ interest in cache content and obtain the cache content state probability prediction equation, and use the cache content state probability prediction equation to predict the cache content prevalence. Second, based on the predicted prevalence results, a prevalence predictive genetic-annealing cache content algorithm (PGAC) is proposed with the optimization objective of maximizing the cache success ratio. The algorithm designs the selection function of the traditional genetic algorithm as a simulated annealing selection function based on the cache content success ratio, which avoids the defect of the genetic algorithm that converges to the locally optimum cache strategy too early and enhances the cache success ratio. Finally, the optimum cache content decision is solved by iterative alternation. Simulation results demonstrate that CDSED strategy can enhance cache success ratio than the LRU strategy, the LFU strategy, and the MPC strategy.

An efficient key tag missing identification protocol for multiple regions in the Industrial Internet of Things

Radio Frequency Identification (RFID) is a special wireless network technology that uses radio frequency communication to achieve non-contact automatic identification through tags affixed to items. As one of the core technologies for physical layer communication in the Industrial Internet of Things(IIoT), RFID technology has been widely used in inventory management, supply chain management, access control identification, and many other areas. In practical application scenarios, the value and importance of some special tags far exceeds that of other tags. Therefore, in many cases, managers only need to pay attention to the status of these special tags, i.e., key tags, and not the status of all tags. However, the response of ordinary tags to reader commands will seriously interfere with identifying key missing tags. Therefore, we propose a novel protocol, Random Grouped Missing Key Tag Identification (RGKMTI), designed for multi-region key tag identification. RGKMTI employs a region-based sequential tag identification method to identify each group of tags individually, which effectively reduces collision slots and utilizes the duality property of slots containing only two key tags during the missing key tag verification phase, where the reader can verify two tags by transmitting at most a single tag ID, which significantly reduces the transmission load and shortens the total execution time. The experimental results show that the RGKMTI is significantly better than the existing schemes in terms of execution time and time efficiency, even though it reduces the identification time by 19.83% and improves the time efficiency by 6.82% compared with the best existing schemes.

Hybrid Clustering Approach (SG-MFOA) using Multipath Cross-Layer Design in MANET Network

Mobile Ad-hoc Networks (MANETs) are used in a wide range of applications because of their unique capabilities. The routing in MANET is regarded as a main challenge on account of its permanent movement and nodes' randomness that can cause a continual change of network topology, thus finding correct paths among the nodes is the fundamental task of routing protocols. There is a rise in protocols that depend on cross-layer communication across several layers to increase the MANET performance. In this manuscript, a Hybrid Clustering Approach (SG-MFOA) using a Multipath Cross-Layer Design in a MANET Network is proposed. Here, multiple routes are selected for data packet transmission with the help of hybrid routing. Furthermore, a cross-layer metric is acquired depending upon Expected Transmission Time (ETT), Residual Energy and Load Balancing Factor. It is necessary to select a Cluster Head (CH) depending on this trade for proficient routing. So, the cluster head is optimally chosen to utilize SG-MFOA. Thus, the multipath route selection is performed by the multi-objective functions containing bandwidth, congestion delay, transmission delay and to ensure the prolonging of network lifetime, queue delay at each connection Access Category from the available routes to a destination. When compared with the existing methods, like a proficient self-attention-based conditional variational auto-encoder generative adversarial networks-based multipath cross-layer design routing paradigm for MANET (SCVAGAN-MCDR-MANET), Energy Aware Cross Layer Routing Protocol to Increase Route Reliability in MANETs (EACLRP-RR-MANET), Cross-layer Adaptive Fuzzy-based Ad hoc On-Demand Distance Vector Routing Protocol for MANET (CLAF-DVRP-MANET), respectively.

A comprehensive study on the romax-based comprehensive shaping method for skewed cylindrical gears

Abstract Tooth profile modification is one of the effective ways to solve the vibration and noise problems in gear transmission. This article is based on the dynamic Romax Designer software for simulation and studies the micro modification problem of helical cylindrical gears in a certain reducer. Based on the analysis of the limitations of tooth profile modification and tooth orientation modification methods, a comprehensive tooth profile modification method is proposed. The simulation results show that the transmission error, load distribution, meshing situation, and service life of the gear have improved after adopting the comprehensive modification method, thereby improving the transmission accuracy, reliability, and durability of the gear. This method can provide reference and reference for gear modification of reducers.

In vivo mechanical response of thigh soft tissues under compression: A two-layer model allows an improved representation of the local tissue kinematics

Biomechanical parameters have the potential to be used as physical markers for prevention and diagnosis. Finite Element Analysis (FEA) is a widely used tool to evaluate these parameters in vivo. However, the development of clinically relevant FEA requires personalisation of the geometry, boundary conditions, and constitutive parameters. This contribution focuses on the characterisation of mechanical properties in vivo which remains a significant challenge for the community. The aim of this retrospective study is to evaluate the sensitivity of the computed elastic parameters (shear modulus of fat and muscle tissues) derived by inverse analysis as a function of the geometrical modelling assumption (homogenised monolayer vs bilayer) and the formulation of the cost function. The methodology presented here proposes to extract the experimental force-displacement response for each tissue layer (muscle and fat) and construct the associated Finite Element Model for each volunteer, based on data previously collected in our group (N = 7 volunteers) as reported in (Fougeron et al., 2020). The sensitivity analysis indicates that the choice of the cost function has minimal impact on the topology of the response surface in the parametric space. Each surface displays a valley of parameters that minimises the cost function. The constitutive properties of the thigh (reported as median ± interquartile range) were determined to be (μ=198±322Pa,α=37) for the monolayer and (μmuscle=1675±1127Pa,αmuscle=22±14,μfat=537±1131Pa,αfat=32±7) for the bilayer. A comparison of the homogenised monolayer and bilayer models showed that adding a layer reduces the error on the local force displacement curves, increasing the accuracy of the local kinematics of soft tissues during indentation. This allows for an increased understanding of load transmission in soft tissue. The comparison of the two models in terms of strains indicates that the modelling choice significantly influences the localization of maximal compressive strains. These results support the idea that the biomechanical community should conduct further work to develop reliable methodologies for estimating in vivo strain in soft tissue.

In vivo measurement of strain in the periodontal space of pig (Sus scrofa) incisors using in-fiber Bragg sensors.

The incisor teeth in pigs, Sus scrofa, function in association with a disc-shaped snout to explore the environment for potential food. Understanding how mechanical loading applied to the tooth deforms the periodontal ligament (PDL) is important to determining the role of periodontal mechanoreceptors during food exploration and feeding. The objective of this study was to use fiber Bragg (FBG) sensors to measure strain in vivo within the PDL space of pig incisors. The central mandibular incisors of pigs underwent spring loaded lingual tipping during FBG strain recording within the labial periodontal space. FBG sensors were placed within the periodontal space of the central mandibular incisors of ~2-3-month-old farm pigs. The magnitude and orientation of spring loads are expected to mimic incisor contact with food. During incisor tipping with load calibrated springs, FBG strains in vitro (N = 6) and in vivo (N = 6) recorded at comparable load levels overlapped in range (-10-20 με). Linear regressions between peak FBG strains, that is, the highest recorded strain value, and baseline strains, that is, strain without applied spring load, were significant across all in vivo experiments (peak strain at 200 g vs. baseline, p = .04; peak strain at 2000 g vs. baseline p = .03; peak strain at 2000 g vs. 200 g, p = .004). These linear relationships indicate that on a per experiment basis, the maximum measured strain at different spring loads showed predictable differences. A Friedman test of the absolute value of peak strain confirmed the significant increase in strain between baseline, 200 g, and 2000 g spring activation (p = .02). Mainly compressive strains were recorded in the labial PDL space and increases in spring load applied in vivo generated increases in FBG strain measurements. These results demonstrate the capacity for FBG sensors to be used in vivo to assess transmission of occlusal loads through the periodontium. PDL strain is associated with mechanoreceptor stimulation and is expected to affect the functional morphology of the incisors. The overall low levels of strain observed may correspond with the robust functional morphology of pig incisors and the tendency for pigs to encounter diverse foods and substrates during food exploration.

Yoga and its effect on sperm genomic integrity, gene expression, telomere length and perceived quality of life in early pregnancy loss.

Achieving successful pregnancy outcomes is a delicate interplay between the maternal and the fetal counterparts. Paternal factors play a critical role in health and disease of offspring. Early pregnancy loss (EPL) is a psychologically devastating condition affecting the quality of life (QOL). Thus, it needs to be managed by a mind body integrated approach like yoga.The prospective single arm exploratory studyincluded male partners of couples experiencing recurrent pregnancy loss (RPL, n = 30), and recurrent implantation failure (RIF, n = 30) and semen samples wereassessed at the beginning and completion of yoga (6weeks) (WHO 2010).A significant increase in the sperm concentration, motility, decrease in seminal ROS, DFIand increase in relative sperm telomere length was found at the end of yoga. The relative expression of genes critical for early embryonic developmentnormalized towards the levels of controls. WHOQOL-BREF questionnaire scores to assess QOL also showed improvement.Integration of regular practice yoga into our lifestyle may help in improving seminal redox status, genomic integrity, telomere length, normalizing gene expression and QOL, highlighting the need to use an integrated, holistic approach in management of such cases. This is pertinent for decreasing the transmission of mutation and epimutation load to the developing embryo, improving pregnancy outcomes and decreasing genetic and epigenetic disease burden in the next generation.

Replica fault-tolerant scheduling with time guarantee under energy constraint in fog computing

Fog computing offers stronger local computing power and reduces data transmission load, making it an ideal solution to meet the energy-saving and efficient requirements of intelligent connected vehicle applications. As intelligent networked vehicles and vehicle–road collaboration technologies advance rapidly, optimizing scheduling under fog computing architecture has become a prominent research area. However, existing studies primarily concentrate on parallel task scheduling with low energy consumption or high real-time performance, failing to address the requirement for high reliability in intelligent networked vehicle scenarios. To achieve time and reliability optimization for vehicular applications in fog computing architecture, this paper proposes a fog computing task scheduling algorithm and explores its extension using replication techniques. Subsequently, the algorithm underwent evaluation utilizing randomly generated directed acyclic graph models as well as real-life automotive application instances. The experimental findings indicate that in comparison to existing methods, the proposed algorithm exhibits a notable improvement in reliability while ensuring time optimization, thereby demonstrating a distinct level of advancement and practicality.

Causes of low back pain (LBP) in women without pregnancy, in relation to different age groups during the reproductive period, are primarily treated as musculoskeletal disorders: a retrospective study

Introduction: Low back pain (LBP) is a musculoskeletal disorder of several causes that can mess up the spine. It is characterized by pain, stiffness or muscle tension and is usually localized in the lumber region. – During their working years, people frequently experience low back pain. Approximately 84% of adults experience LBP once or more during their lifetime. In Bangladesh, wt. related prevalence of LBP is 18.5% and age group 18-34 years prevalence are 10.5% and >55 years 27.8%, average 19.2%, which is more in women 27.2% than men. Pain in the soft tissue of the back is extremely common among adults and often affects individuals during their working years. LBP in women, is strongly linked to hormonal and reproductive factors, the work environment and lifestyle. Females frequently experience lower abdominal and back pain at reproductive age, usually due to PMS, PMDD, dysmenorrhea, endometriosis, pregnancy, menopause, muscle spasms, arthritis, UTI, PID, HTN, DM, obesity, multiple C/S tracts and lower abdominal operations, all of which cause RAD, osteoporosis, vertebral and intervertebral disc diseases (PLID, herniation, slipping etc.). The L4 and L5 neural arches are involved in the transmission of a considerable load. Therefore, the joints between the articular facets of L4 and L5,- are sites of LBP. Low back pain (LBP) was diagnosed by history and clinical examination according to the Pain Scale. To determine the cause of HELLP syndrome/causes by routine investigations and sometimes abdominal ultrasonography (USG), magnetic resonance imaging (MRI) is needed. Treatment of LBP depends on the cause. When a definite lesion is not found, the patient should be informed and reassured about the treatment of LBP. Purpose/Objective of the study: To identify the causes of LBP and prevalence of LBP in women of reproductive age excluding pregnant individuals and establish referral guidelines. Methodology: This was a retrospective (observational) cross sectional study jointly conducted by Orthopedics and Gynecology Expertise in the North-East region, named the Sylhet Division of Bangladesh. Female patients were considered to be of reproductive age for the last three (3) years (2020 - 2022) at the Z&J fellows medical institution. The data were collected from the medical records of computer databases with preset questionnaires and written informed consent. The 1st part of the questionnaire consisted of questions about the causes of LBP, and the 2nd part consisted of LBP-related questionnaires. Patients were selected by the inclusion and exclusion criteria. The data were analyzed with SPSS 25.0 statistical software, MS Word and Excel version 2010. Descriptive statistics were analyzed, i.e. - frequency, central tendency and dispersion, i.e. range, standard deviation and variance. Tests of “proportions” and “significance” were performed via sample t-tests and ANOVA. Statistical data analysis was used to evaluate the correlation of LBP incidence and intensity (%) with age, BMI, disease status, marital status, obstetric history, working history and posture of reproductive-age women. Summary: LBP has multiple causes. In retrospective studies, there is no way to predict the prevalence of causes rather, the prevalence of causes can be determined before patients are affected. In our study, we explored the causes of LBP in women according to age, BMI, local and systemic diseases, marital history, obstetric history, working history and posture. The prevalence of LBP was greater in the 41-50 years age group (34.7%) and in the 20-30 years age group (34.2%). Moreover, overweight and obesity are associated with LBP. Overall 5.3% and 12.8% of the participants were overweight and obese, respectively, and were aged >20-30 years with LBP. Patient age, BMI, disease status, marital status, obstetric history and working history had no effect on any of the patients, but some patients had LBP; overweight, obesity, age group and working posture had direct effects on LBP incidence (p>0.05). LBP is more common in women- than in men and may be due to household activities and a greater frequency of visceral pain during menstruation, pregnancy and labor. Conclusion: Low back pain (LBP) can occur in multiple physical conditions in women of reproductive age except during pregnancy and can disrupt the back tissues of the lumbosacral region. Women are more susceptible to LBP because of menstrual and obstetric factors. A diagnosis was made by obtaining a meticulous detailed medical history, performing a physical examination and performing proper investigations. The causal parameters revealed that LBP had no effect on any of the patients, but women of reproductive age may suffer from LBP due to differences in cause.

Robust profiled carbon rovings made of multiple yarns for textile reinforcements in concrete and asphalt matrix

The load-bearing behavior and the performance of composites depends largely on the bond between the individual components. Conventional grid-like textile reinforcement structures with thin and smooth yarn structures transmit forces primarily by an adhesive bond with the surrounding matrix. A sufficient load transmission is not possible. Thick, pultruded rebars made of fiber-reinforced plastics can be profiled by subtractive (e.g. milling) or additive (e.g. wrapping) techniques in order to create a rip-like structure and increased shear bond. Yet the discontinuous fiber course results in material inefficiency. A newly developed profiling technique allows a tetrahedral profiling of the complete roving structure, yet considering its anisotropic properties. In the article, we present this approach, and the first results from single yarn tensile and pull-out tests of single, double and triple plied profiled rovings in concrete and asphalt matrix. Thus, the highest bond is achieved in the brittle concrete matrix. Plied rovings with strong tetrahedral profiles show up to 600% higher bond stress compared with rovings with circular profiles, while maintaining high tensile properties. However, splitting-induced failure of the reinforced test specimens occurs, making plied profiled rovings favorable for high concrete cover and less brittle matrixes; for example, asphalt. The reinforced asphalt specimens show at −10°C similar bond properties, but at 30°C the bond decreases by 80%. In summary, the study shows that bond properties of profiled rovings are superior to conventional circular rovings, and promise a high material efficiency for use in concrete and asphalt reinforcements.

Influence of B4C and ZrB2 reinforcements on microstructural, mechanical and wear behaviour of AA 2014 aluminium matrix hybrid composites

Considering their affordability and high strength-to-weight ratio, lightweight aluminium alloys are the subject of intensive research aimed at improving their properties for use in the aerospace industry. This research effort aims to develop novel hybrid composites based on AA 2014 alloy through the use of liquid metallurgy stir casting to reinforce dual ceramic particles of Zirconium Diboride (ZrB2) and Boron Carbide (B4C). The weight percentage (wt%) of ZrB2 was varied (0, 5, 10, and 15), while a constant 5 wt% of B4C was maintained during this fabrication. The as-cast samples have been assessed using an Optical Microscope (OM) and a Scanning Electron Microscope (SEM) with Energy Dispersive Spectroscopy (EDS). The properties such as hardness, tensile strength, and wear characteristics of stir cast specimens were assessed to examine the impact of varying weight percentages of reinforcements in AA 2014 alloy. In particular, dry sliding wear behaviour was evaluated considering varied loads using a pin-on-disc tribotester. As the weight % of ZrB2 grew and B4C was incorporated, hybrid composites showed higher hardness, tensile strength, and wear resistance. Notably, the incorporation of a cumulative reinforcement consisting of 15 wt% ZrB2 and 5 wt% B4C resulted in a significant 31.86% increase in hardness and a 44.1% increase in tensile strength compared to AA 2014 alloy. In addition, it has been detected that wear resistance of hybrid composite pin (containing 20 wt% cumulative reinforcement) is higher than that of other stir cast wear test pins during the whole range of applied loads. Fractured surfaces of tensile specimens showed ductile fracture in the AA 2014 matrix and mixed mode for hybrid composites. Worn surfaces obtained employing higher applied load indicated abrasive wear with little plastic deformation for hybrid composites and dominant adhesive wear for matrix alloy. Hence, the superior mechanical and tribological performance of hybrid composites can be attributed to dual reinforcement particles being dispersed well and the effective transmission of load at this specific composition.

Mechanical Properties of Basalt / Chopped E-Glass Fiber and Graphite Powder Reinforced Hybrid Composites

In the current investigation an effort has put to study the effect of E-glass chopped mat and graphite powder in variations of 5g, 10g, and 15g on the tensile and flexural behavior of a basalt fiber-reinforced epoxy composite laminate reinforced with E-Glass fiber and Graphite powder. Hand layup technique has been used for the fabrication of the composites. Tensile, flexural, impact, and hardness tests were done on the Basalt/E-glass/Graphite epoxy composite in accordance with ASTM standards. The results indicate significant improvement in tensile strength, impact strength and hardness when E-glass was incorporated in the basalt/epoxy composite. However, basalt/E-glass/10% graphite epoxy composite was shown to have a greater flexural strength. An excellent dispersion of the reinforcements in the polymeric matrix, which elevated surface area for solid interfacial contact and effective load transmission, could possibly be accountable for the improved performance of the laminates that were successfully developed.

Design and Optimization of Rear Wheel Assembly in All-Terrain Vehicle

Abstract: Suspension is one of the automobile's critical subsystems. Isolating the driver from the shocks of the road is the ultimate purpose. The need of sufficient wheel travel, lateral stability, load transmission, and driver comfort are elements of secondary functions. The study details the design and improvement of an ATV's braking and rear wheel suspension systems. The vehicle was designed under the terms of rules framed by the SAE Organization. The suspension provides the most effective achievable camber, caster, toe, anti-dive, Roll Center, and improvements since it is made for tough terrain. Additionally, there are also calculations, mounting considerations, and shock absorber presented. A prime instance of a commercial software package that studies suspension geometry is Lotus Shark. With the commercial program ANSYS WOKRBENCH, different suspension components are subjected to finite element analysis. All knuckle tests were performed on aluminium alloys 7075 and Hub EN24.

Efficient data-driven event-triggered predictive control for cyber-physical systems

As a multi-dimensional complex system that integrates computing, network, and physical environments, cyber-physical system (CPS) involves a large amount of system data in its real-time control process. The efficiency of data processing and transmission in CPS plays an important role in its control performance, however, few results have addressed such problems. This paper proposes a novel data-driven event-trigger mechanism to alleviate the data processing and transmission load for the data-driven predictive control method in CPS. The design of the event-triggered law can be transformed into solving a linear matrix inequality (LMI) based on the measured system data, while ensuring the stability of the integrated system. The improved performances are illustrated by the explicit simulation results, which indicates its potential application in CPS.

Quantifying Bone and Skin Movement in the Residual Limb-Socket Interface of Individuals With Transtibial Limb Loss Using Dynamic Stereo X-Ray: Protocol for a Lower Limb Loss Cadaver and Clinical Study.

Relative motion between the residual limb and socket in individuals with transtibial limb loss can lead to substantial consequences that limit mobility. Although assessments of the relative motion between the residual limb and socket have been performed, there remains a substantial gap in understanding the complex mechanics of the residual limb-socket interface during dynamic activities that limits the ability to improve socket design. However, dynamic stereo x-ray (DSX) is an advanced imaging technology that can quantify 3D bone movement and skin deformation inside a socket during dynamic activities. This study aims to develop analytical tools using DSX to quantify the dynamic, in vivo kinematics between the residual limb and socket and the mechanism of residual tissue deformation. A lower limb cadaver study will first be performed to optimize the placement of an array of radiopaque beads and markers on the socket, liner, and skin to simultaneously assess dynamic tibial movement and residual tissue and liner deformation. Five cadaver limbs will be used in an iterative process to develop an optimal marker setup. Stance phase gait will be simulated during each session to induce bone movement and skin and liner deformation. The number, shape, size, and placement of each marker will be evaluated after each session to refine the marker set. Once an optimal marker setup is identified, 21 participants with transtibial limb loss will be fitted with a socket capable of being suspended via both elevated vacuum and traditional suction. Participants will undergo a 4-week acclimation period and then be tested in the DSX system to track tibial, skin, and liner motion under both suspension techniques during 3 activities: treadmill walking at a self-selected speed, at a walking speed 10% faster, and during a step-down movement. The performance of the 2 suspension techniques will be evaluated by quantifying the 3D bone movement of the residual tibia with respect to the socket and quantifying liner and skin deformation at the socket-residuum interface. This study was funded in October 2021. Cadaver testing began in January 2023. Enrollment began in February 2024. Data collection is expected to conclude in December 2025. The initial dissemination of results is expected in November 2026. The successful completion of this study will help develop analytical methods for the accurate assessment of residual limb-socket motion. The results will significantly advance the understanding of the complex biomechanical interactions between the residual limb and the socket, which can aid in evidence-based clinical practice and socket prescription guidelines. This critical foundational information can aid in the development of future socket technology that has the potential to reduce secondary comorbidities that result from complications of poor prosthesis load transmission. DERR1-10.2196/57329.

Shock Absorption Capacity of High-Performance Polymers for Dental Implant-Supported Restorations: In Vitro Study.

Restorative materials might significantly affect load transmission in peri-implant bone. The aim of the present study is to evaluate the shock absorption capacity of two different polymeric materials to be used for implant-supported prostheses. A masticatory robot was used to compare the shock absorption capacity of veneered and non-veneered polyetherketoneketone (PEKK), Pekkton®ivory (Cendres+Mètaux), and the glass fiber-reinforced composite (GFRC), TRINIATM (Bicon). Five identical sample crowns for each of the three groups were tested. Forces transmitted at the simulated peri-implant bone were recorded and statistically analyzed. The statistical analysis of forces transmitted at the simulated dental implant revealed significant differences between the materials tested and between these materials and zirconia, glass ceramic, composite resin, and acrylic resin. Only differences between PEKK and veneered PEKK and between PEKK and one of the previously tested composite resins were not statistically significant. PEKK samples demonstrated significantly greater shock absorption capacity compared to GFRC. PEKK revealed optimal shock absorption capacity. Further studies are needed to evaluate its efficacy in the case of long-span prostheses with reduced prosthetic volume.

Two-dimensional imaging of elastic properties of rock core samples from measurements of angle-dependent ultrasonic reflection coefficients

Laboratory and field measurements often fail to identify small-scale variations in rock elastic properties. Due to limited spatial resolution, conventional laboratory methods cannot properly describe rock formations exhibiting a high degree of heterogeneity, thereby masking differences between stiff and compliant layers. Continuous sample measurements can mitigate this problem but are not widely used by the industry. We build upon our previous work and apply laboratory angle-dependent ultrasonic reflection coefficient (ADURC) measurements to achieve detailed two-dimensional descriptions of the elastic properties of complex rock samples. This method successfully yields high-resolution information on P- and S-wave velocities, as well as bulk density, across the surface of rock samples. Elastic properties are estimated using a nonlinear inversion algorithm that matches laboratory measurements with numerical simulations. ADURC data acquired at various sample locations enable detailed rock descriptions, where the effective measurement area is determined by the size of the receiver, measurement frequency, and incidence angle. Consequently, the sampling area is smaller compared with triaxial loading and acoustic transmission tests, for which the resolution is controlled by sample size. Measurements conducted on samples exhibiting different levels of spatial complexity validate the capability of the ADURC method to identify small-scale heterogeneities. For the reported experiments, variations in angle-dependent reflectivity give rise to corresponding variations in the estimated P- and S-wave velocities and density, which can exceed 60%. These small-scale variations across heterogeneous rock samples often are overlooked by conventional laboratory methods.

Analytical model of meshing stiffness, load sharing, and transmission error for internal spur gears with profile modification

The influence of the teeth geometry on the load distribution, transmission error, and meshing stiffness of internal spur gears is very similar to that of external gears. Therefore, the formulation of the models for strength and dynamic calculations for internal and external gears is also similar. However, the internal gears have usually greater values of the contact ratio, frequently above 1.8, even 1.9. In these cases, the lengthening of the contact interval due to the elastic deflections of the teeth may result in an effective contact ratio greater than 2, with the subsequent changes in the load sharing and transmission error. These changes are not properly described by the theoretical models for high contact ratio spur gears. In this paper, a model of load sharing, quasi-static transmission error, and time-varying meshing stiffness for internal spur gears with profile modification is presented, which has been applied to low contact ratio internal gears which, due to the transmitted load, become high contact ratio internal gears. The influence of the variations of the transmitted load on the load capacity is also studied.