Deformation Values Research Articles

Pressure-relief joints of initial support structural system used in tunnels with high-stress surrounding rock.

To address the problem of large deformations in weak surrounding rock tunnels under high ground stress, which cause damage to initial support structures, this study proposes a novel type of circumferential pressure-relief joint based on the concept of relieving deformation pressure of the surrounding rock. Key parameters of the pressure-relief joint, such as initial bearing capacity peak, constant bearing capacity, and allowable pressure-relief displacement, were obtained through numerical simulations and laboratory experiments. A comparison was made between the mechanical characteristics of rigid joints and the new type of pressure-relief joint. The applicability of the pressure-relief joint was verified through field tests, monitoring the surrounding rock pressure, internal forces in the steel frames, and the convergence displacement of the support structure. The results show that: (1) In the elastic stage, the stiffness of the new pressure-relief joint is similar to that of rigid joints. In the plastic stage, rigid joints fail directly, whereas the pressure-relief joint can control deformation and effectively release the deformation pressure of the surrounding rock while providing a constant bearing capacity. (2) The right arch foot in the experiment had poor rock quality, leading to high stress in the steel frame and significant horizontal displacement. After the deformation of the pressure-relief joint, the stress in the surrounding rock and steel frame significantly reduced, and the rate of horizontal deformation of the support structure slowed down. (3) The vertical and horizontal final displacements of the pressure-relief joint in the experiment were 61mm and 15mm, respectively, which did not exceed the allowable deformation values. The components of the support structure remained intact, ensuring safety. However, this study has limitations: the design of the new pressure-relief joint only allows for a vertical deformation of 150mm and a horizontal deformation of 50mm, limiting the range of pressure-relief deformation.

Reinforcing preloaded steel I-beams by considering welding heat effects and geometric imperfections

Steel I-beams are often strengthened by welding steel cover plates to the bottom flanges of the beams. However, very limited studies have been conducted on the effect of welding heat on the behaviour of I-beams reinforced while under load. This paper presents a finite element (FE) analysis-based study on the behaviour of preloaded steel I-beams reinforced with cover plates welded to the bottom flanges of beams, considering welding procedure simulation. FE analysis is conducted to study the effects of welding heat, welding sequence, and weld length on the residual welding deformation and behaviour of steel I-beams reinforced while under load. It is observed that an appropriate welding sequence and weld length can reduce the residual lateral deformations induced from welding of a reinforcing plate to the bottom flange of the preloaded I-beam and thus control the unfavourable welding effects. Based on the analyses, a welding segment length of L/9, where L is the length of the beam, is recommended for practical applications. In addition, FE analysis shows that the direction and magnitude of the initial geometrical imperfection can change the value and direction of the residual deformation resulting from welding. Furthermore, it is observed that preloading does not have any significant effect on the behaviour and ultimate capacity of the I-beam reinforced at a preload level up to 50% of the strength of the unreinforced beam. Also, when compared with the current standards AISC 360-16 and CSA S16-9, FE analysis of reinforced steel I-beams considering welding simulation shows that the current standards significantly overpredict the moment capacities of the reinforced beams when the top flange loading effect is not considered.

Геодезичне забезпечення відновлення багатофункціонального комплексу ТРЦ «Нікольський» в місті Харків

The application of geodetic surveys is a vital aspect of assessing the destruction of buildings as a result of Russian armed aggression. The study compares Ukrainian and foreign research methods, highlights their advantages and disadvantages. The legislative framework for geodetic support for restoration of buildings on the territory of Ukraine has been analyzed. As international experience has shown, geodetic surveys are an effective tool for assessing the destruction of buildings as a result of military operations. The study is aimed at evaluating the structural integrity on the example of the shopping and entertainment center “Nikolskyi” in the city of Kharkiv. Geodetic methods used to assess structural damage are reviewed, and an overview of the results of these damage assessments is provided. It is investigated how geodetic surveys can be used to assess structural damage in buildings. The purpose of the article is the study of geodetic works and methods of geodetic support for restoration works of the shopping center building. To achieve the goal, the following tasks were performed: analysis of previous experience in this area; the choice of the method of geodetic provision of restoration works; presenting the results of geodetic measurements; interpretation of the obtained results. Method. To obtain research results, special methods are used: constructive and substantive analysis – for the formation of research directions; analytical methods – to process the results of the shooting; mathematical modeling – to determine the amount of destruction and damage to the building. A Leica Geosystems TCRP 1205 tacheometer and other geodetic equipment were used in the study to assess the structural integrity of the shopping center. The combination of geodetic measurements with the use of tacheometers is an important area of application of tacheometers in similar tasks. In addition, classical surveys, using total station geodetic measurements, were performed in conjunction with an automatic strain monitoring system to ensure the accuracy and reliability of the structural integrity assessment. Therefore, using the specified devices, it is possible to accurately measure and analyze the structural integrity of the shopping center. Scientific novelty and practical significance. The scientific novelty of the conducted research consists in the creation of modern approaches to geodetic support for restoration works of buildings that were destroyed as a result of military operations. Original methods of geodetic surveying and a modern instrument base from NVP “Navigation and Geodetic Center” are applied. The proposed geodetic studies demonstrate the effectiveness of using geodetic measurements to assess structural damage to buildings. Deformation values obtained with the help of geodetic studies helped determine the volumes and technology of restoration, which provides important information for engineering works. It has been shown that the use of electronic tacheometer measurements is a reliable and accurate means of determining damage levels and locations even in complex fracture locations. The Leica TCRP 1205 total station accurately measures angles and distances in a reflection-free mode to achieve the highest accuracy of work. In addition, the measuring technology that was applied at the object of research can be used for geodetic research during the detection of shifts and deformations of building structures. Future research could explore the application of geodetic measurements to other types of buildings or structures damaged by military action. In general, the studies carried out reinforce the potential and importance of geodetic measurements for restoration programs that are planned and will be planned in the near future.

Effects of using UHSS material for weight reduction of Cukurova 885 model backhoe loader boom element

Construction machines have played an important role in building and sustaining civilizations in all walks of human life by making human life easier for centuries. These heavy machines consume a lot of fuel due to their high energy consumption and cause severe damage to the environment. Studies are being conducted to avoid harmful gas emissions due to fuel consumption of vehicles. One of the methods used in these studies is weight reduction. In this study, the fuel saving achieved by weight reduction with the material change in the boom element of a backhoe loader was investigated. The 3D model of the boom element of the backhoe loader model Cukurova885 was used for the study. The Ansys Workbench Software was used for the study. The weight of the reference model was reduced by reducing the dimensions of the reference model by using Ansys Spaceclaim in the software. Ultra-High Strength Steel with the same density but higher strength was used instead of the ST52 material currently used. The structural analyzes were carried out using the finite element method by applying exactly the same loads to the ST52 reference model and the weight-reduced UHSS model. In the study, thickness reductions on the model were made in Ansys Space Claim, a component of Ansys Workbench Software. In the Space Claim component, changes can be made to the geometry of a model imported into Ansys. For static structural analysis, Ansys Mechanical, a component of Ansys Software, was used. The model, whose thickness and therefore its weight is reduced in Space Claim, is opened in Mechanical, the necessary parameters are entered and it is prepared for analysis. Afterwards, analysis is performed via Ansys Mechanical. Comparing the results obtained, it was found that the weight of the model decreased by 23.16% and a fuel saving of 16.49% was achieved by using UHSS. Higher deformation and stress values were obtained for the model with UHSS. The safety factor was found to be 1.22 for the ST52 model and 2.14 for the UHSS model.

Pengaruh Interpass-temperature pada Pengelasan SMAW Terhadap Deformasi dan Kekuatan Impak Baja ASTM A36

Currently, welding is still very necessary for the increasingly advanced development of technology in the construction sector because it plays an important role in metal engineering and maintenance. This research aims to determine the effect of interpass temperature on deformation of weld results in ASTM A36 steel material. The method used in this research is an experimental method by measuring the deformation of the welded specimen. There are 9 specimens, the welding process uses shielded metal arc welding (SMAW), direct current reverse polarity (DCRP) with interpass temperature variations of 75 °C, 100 °C and 150 °C. The measurement results show deformation values ​​of 2.2°, 3.5° and 4° for each of the interpass temperatures of 75 °C, 100 °C and 150 °C. From the results of impact testing on specimens with interpass temperatures of 75 °C and 100 °C, it shows mixed fracture, namely brittle fracture and ductile fracture. The results of impact testing on specimens with an interpass temperature of 150 °C showed brittle fracture. The highest strength was at interpass temperature specimen of 100 °C, that is 211.79 Joules. And the lowest impact strength occurred in the interpass temperature specimen at 150 °C, that is 183.16 Joules.

GEODETIC MONITORING OF DEFORMATIONS OF BEARING REINFORCED CONCRETE STRUCTURES OF AN UNDERGROUND MULTI-FUNCTIONAL PUBLIC CENTER

The article highlights the stages of carrying out measurement and survey work of an underground multifunctional public center to assess the technical condition of the load-bearing structural elements of block 1 and the entrance group in order to carry out reconstruction on the above-ground part of the building. The reconstruction consisted of installing metal structures on the eastern and western sides of the dome and a metal canopy over the entrance group. As a result of a technical examination and geodetic observations, cracks with an opening width of 0.5 mm and significant deflections in the floor slabs and crossbars at the upper and lower levels were identified in the load-bearing structures. To ensure safe operation and timely detection of dangerous values of deformation of a unique building with an increased class of responsibility, an effective method of geodetic monitoring of deflections of reinforced concrete floor slabs and crossbars and recommendations for their strengthening, taking into account the location of the construction site at the intersection of zones of influence of several tectonic faults, are proposed. Geodetic observations of deformation processes were carried out. Based on the results of the measurements, it was decided to strengthen the reinforced concrete structures by gluing fiber-reinforced composite materials to the lower part of the floor slabs. A comparative analysis of the obtained quantitative parameters of shifts of load-bearing structures makes it possible to assess the technical condition of an underground building and its individual structures before and after strengthening measures.

Экспериментальные исследования динамической работы железнодорожных мостов при воздействии высокоскоростного подвижного состава

The issue of considering the dynamic interaction of the railway rolling stock and the structures of bridge structures is especially important when solving the tasks of increasing the speeds of trains on the existing railway lines, as well as when prescribing high-speed mode on designed bridges. Rational accounting of the parameters of dynamic interaction allows you to perform complete and reliable calculations of elements of bridge structures, which in turn has a beneficial effect on predicting the period and nature of the operation of structures and, because of the economic component of projects. The modern solution to the problem of dynamic interaction is reduced to determining the degree of influence of each component of the unified mechanical system of the bridge-travel. Objective: the purpose of this study is to determine the parameters of dynamic interaction through experimental measurements of stresses, accelerations, and displacements of structures of the bridge structure located on the existing railway line with an organized high-speed traffic movement. Methods: experimental measurement using high-frequency voltage sensors, accelerations and movements with subsequent statistical processing and analysis of the results. Results: graphs and tables displaying a change in the measured values of relative deformations, accelerations, and movements over time. Practical importance: The practical significance of this study is to assess the degree of influence of the components of the dynamic interaction of high-speed rolling composition and the bridge structure, which allows you to form a holistic picture of the nature of the process of dynamic interaction.

Дослідження відносних деформацій міжуламкового регенерату в моделях різних варіантів остеосинтезу кісток гомілки з переломами в середній третині у дітей з недосконалим остогенезом та незавершеним ростом

Introduction. Osteogenesis imperfecta is a genetic pathology that leads to a violation of the processes of formation of collagen fibers, formation of bone matrix and its mineralization and, as a result, to the formation of bone tissue with low strength properties. The most promising means of stabilizing bone fragments under this condition are intramedullary fixators of various designs. Aim. To investigate the relative deformations of the interfragmentary regenerate under the influence of various types of loads in models of the tibia with fractures of both bones in the middle third and their osteosynthesis using intramedullary rods of various designs in children with osteogenesis imperfecta and incomplete growth. Materials and methods. Mathematical modeling of options for osteosynthesis of tibia bones with a fracture in the middle third in children with osteogenesis imperfecta was performed. Two variants for tibial osteosynthesis were modelled: a rod without rotational stability; rod with rotational stability. Osteosynthesis of the fibula was not modelled in all variants. The stress-strain state of the model under the influence of vertical compressive, bending and torsional loads, as well as the magnitude of the relative deformations of the interstitial regenerate, were studied. The results. A “growing” intramedullary shear with rotational stability provides essential advantages in the case of torsional loads. The presence of rotational stability makes it possible to ensure two times lower values of relative deformations of interfragmentary regenerates compared to osteosynthesis with a rotationally unstable rod. Under compressive and bending loads, both rods showed almost identical results of relative deformations of bone regenerates. High rates of deformation of interfragmentary tibial regenerates are due to the lack of longitudinal axial stability of both rods, which is the basis for the possibility of increasing their length during the growth of the patient. Conclusions. The use of osteosynthesis with intramedullary rods, which increase during the treatment of tibial fractures in patients with osteogenesis imperfecta, does not ensure a sufficient level of stability for the fixation of bone fragments under compression and bending loads, which leads to the greatest deformations of bone regenerates. A rod with rotational stability provides advantages in resistance to torsional loads, which is determined by twice lower relative deformations of interfragmentary regenerates. No conflict of interests was declared by the authors.

Integrated PSInSAR and GNSS for 3D Displacement in the Wudongde Area

The major limitation of persistent scatterer interferometric synthetic aperture radar (PSInSAR) is that it detects only one- or two-dimensional displacements, such as those in the line of sight (LOS) and azimuth directions, by repeat-pass SAR observations. Three-dimensional (3D) displacement reflects the actual sliding surface and failure mechanism of a slope. To transform LOS deformation into a reliable 3D displacement, a new approach for obtaining the 3D displacement is proposed herein based on the slope deformation (Dslope). First, the deformation value calculated using the Global Navigation Satellite System (GNSS) as a constraint is used to eliminate the residual deformation of PSInSAR. Then, Dslope is obtained from the relationship between DLOS and the slope angle extracted from the digital elevation model (DEM). Finally, according to the geometric relationship between Dslope and DLOS, a novel approach for calculating 3D displacement is proposed. When comparing the 3D displacement extracted by the proposed method and that from GNSS data in Jinpingzi landslide, the root-mean-square error (RMSE) values were ±2.0 mm, ±2.8 mm, and ±2.6 mm in the vertical, north, and east directions, respectively. The proposed method shows high accuracy in 3D displacement calculation, which can help to determine the failure mechanism of a landslide. This method can be widely used in landslide monitoring in wide areas.

Lateral Convergence Deformation Prediction of Subway Shield Tunnel Based on Kalman Model

In order to optimize the structure of a subway shield tunnel, minimize injuries, and avoid potential safety hazards, the lateral convergence deformation of subway shield tunnels should be predicted. In terms of accuracy and stability, existing prediction models perform poorly in obtaining the lateral convergence deformation value of a non-stationary small-sized sample of a subway shield tunnel. In this paper, a lateral convergence model of a subway shield tunnel based on the Kalman algorithm is constructed based on Kalman filtering theory. The model is efficient, adaptive, and robust and can accurately predict the lateral convergence deformation of a subway shield tunnel. Taking the horizontal diameter of a 200-ring shield segment in the interval section of a subway tunnel as an example, we have proved that the residuals of the Kalman prediction model are small, the residual distribution conforms to the normal distribution, and the prediction effect is great. The model is suitable for the prediction of more than five periods of data, and the prediction accuracy of the model improves with an increase in the number of data periods. In addition, in this paper, we compare the Kalman model with the GM(1,1) model and the GM–Markov model, and the RMSE, NRMSE, MAPE, and R2 are used as evaluation indices. The results show that the Kalman model has a higher prediction accuracy and is more suitable for predicting the lateral convergence deformation of a subway shield tunnel.

Research on Collapse Detection in Old Coal Mine Goafs Based on Space–Sky–Earth Remote Sensing Survey

A considerable number of coal mines employed room and pillar mining in the last century in northern China, where the goaf remained stable for a period of time; however, with the increased exposure of coal pillars, their collapse may gradually increase. The stability assessment of these old rooms and pillar goafs is challenging due to their concealment, irregular mining patterns, and the long passage of time. The methodology developed in this study, based on “space-sky-earth” remote sensing such as InSAR to trace historical deformation, the UAV observation of current surface damage, and comparison of mining spaces, can rapidly detect on a large scale the collapse of old goafs and the trend of damage. This study is conducted with an example of a coal mine in Yulin, Northern China, where obtained quantitative surface deformation values were integrated with qualitative surface damage interpretation results, followed by a yearly analysis of the overlying rock movement in accordance with the underground coal mining process. The results show that from 2007 to 2021, corresponding surface deformation and damage occurred following mining progress. However, the room and pillar goaf areas had not undergone any surface deformation, nor had there been incidents of landslides or ground fissures; therefore, it was speculated that no roof collapse had occurred in this region. The surface deformation and damage associated with underground coal mining are complex and influenced by the coal seam occurrence, mining methods, strata lithology, terrain slope, temporal evolution, and anthropogenic modifications. These phenomena are representative of the coal mining area, and this methodology can provide a reference for similar endeavors.

Effect of Sc/Zr ratio on superplastic behavior of ultrafine-grained Al–6%Mg alloys

Al–6%Mg-Sc-Zr alloys with a combined Sc and Zr ratio of 0.32 wt% make up the focus of this research. The content of Sc and Zr varied with an increment of 0.02%. Their ultrafine-grained (UFG) microstructure was formed with Equal Channel Angular Pressing (ECAP). Superplasticity tests were performed at temperatures ranging from 300 to 500 °C and at a strain rate varying between 3.3·10−3 and 3.3·10−1 s−1. The values of strain hardening factor (n), strain rate sensitivity factor (m), and superplastic deformation threshold stress (σp) were determined. The microstructure and failure patterns of the alloys post superplasticity tests were studied. The effect of the Sc/Zr ratio on the superplastic behavior, cavitation fracture and dynamic grain growth of UFG Al–6%Mg alloys was investigated. The satisfiability of Hart's criterion for calculating uniform deformation value under superplastic conditions was verified. Grain boundary sliding and intragranular deformation make comparable contributions to superplastic flow in the UFG aluminum alloys under study. Al–6%Mg-0.20%Sc-0.12%Zr (Sc/Zr = 3.3 at.%) and Al–6%Mg-0.18%Sc-0.14%Zr (Sc/Zr = 2.8 at.%) alloys exhibit the highest superplasticity. Shown that changes in the Sc/Zr ratio affect the precipitating mechanism, spatial distribution and composition of the precipitating particles Al3(ScxZr1-x). The optimal Sc/Zr ∼2.6–3.3 (at.%) ratio for the Al–6%Mg alloy corresponds to an Al3(Sc0.5Zr0.5) and Al3Sc precipitated particles. The large Al3Zr particles formed through the discontinuous precipitation mechanism was detected at Sc/Zr < 1 (at.%).

Evaluating deformation in FRP boat: Effects of manufacturing parameters and working conditions

Abstract Fiber-reinforced plastic (FRP) is utilized in the fabrication of the primary structures of FRP boats. A majority of these structures are produced using molds. Subsequently, these products often experience deformation upon being released from the mold, as well as when they are exposed to high temperatures. Hence, it is crucial to carry out experimental investigations and evaluations related to the deformation of laminated composite structures. The specimens, which are in the form of L-shapes and curve-shapes, are constructed using unsaturated polyester resin and fiberglass material. The study focuses on two independent variables, namely the percentage of hardeners and the temperature during the manufacturing process. The output factor under examination is deformation, which is measured on these specimens. Subsequently, all of the specimens are subjected to varying levels of temperature using an oven as the working condition. The deformation is further assessed based on the experimental findings and regression equation. The results indicate that as the rate of hardener and temperature increase, the level of deformation decreases. Additionally, it was observed that when the temperature rises from 500 to 800°C, the specimens with initial deformation values that are either too high or too low undergo rapid changes. Moreover, the experimental equations can be utilized to predict the values of deformation or input factors.

Structural and Thermal Analysis of Diesel Engine Piston by Changing the Number of Ribs and Materials

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. The power produced by the engine &amp; its efficiency depends on piston. In this paper both Structural &amp; Thermal Analysis is carried out on Diesel engine piston considering three materials such as Aluminum Alloy (Al6061) &amp; Forged Steel also by varying number of ribs. For this Analysis, Modeling of a piston is done using Catia V5 Software &amp; then it is imported into Ansys Workbench. Stress, Strain &amp; Deformation Values are decreased with the increase of Ribs in the Piston Design. The amount of heat flux is more for a piston provided with six ribs. Considering both Structural &amp; Thermal Analysis it is observed that Aluminum Alloy with EIGHT Ribs has shown good results

Vectorial generative adversarial surrogate modeling reliability evaluation framework for engineering structural systems

To effectively evaluate the multi-objective reliability of engineering structural systems, the vectorial generative adversarial surrogate modeling (VGASM) reliability evaluation concept is proposed by integrating the surrogate model, matrix theory, generate adversarial strategy, Copula thought, and linkage sampling technology. In this concept, the surrogate model is employed as a basis function; the matrix theory is applied to establish the vectors and cell arrays of variables and hyperparameters; the generate adversarial strategy is adopted to determine the hyperparameters; the Copula thought and linkage sampling technology are utilized to simultaneously implement multi-objective correlated reliability analysis. Under this concept, the vectorial generative adversarial Kriging (VGAK) reliability evaluation method is developed by combining the Kriging model with VGASM reliability evaluation concept. In addition, a mathematical example and two engineering cases (i.e., aeroengine exhaust gas temperature and turbine blisk multi-failures) are employed to validate the proposed method. The reliability devel of aeroengine exhaust gas temperature and turbine blisk are 0.9989 and 0.9984, when the allowable values of EGT, deformation, and strain are 950 °C, 1.9253 × 10−3 m, and 5.2898 × 10−3 m. Besides, the presented method holds excellent modeling and simulation properties by comparing multiple methods. The study can provide theoretical references for the multi-objective reliability evaluation of engineering structural systems.

Finite Elements Analysis and Topology Optimization of Parking Brake Lever and Ratchet

Topology optimization is known as one of the basic categories of structural optimization. Topology optimization is received increasing attention in many engineering disciplines. Topology optimization contributes to minimizing emissions and environmental effects by increasing material utilization efficiency and manufacturing sustainability. The mechanical parking brake is still used in many vehicles. This study aims to contribute to the reduction in vehicle weight by applying topology optimization. In addition, it also purposes to promote sustainability in manufacturing by reducing material usage and energy consumption. A CAD model was created by considering the existing mechanism element dimensions. The parking brake lever mechanism component was evaluated using topology optimization and finite element analysis methods. Static analyses were performed using a finite element analysis program. The results of this analysis were used as input data for topology optimization. In the topology optimization, the response constraint mass was increased by 5 increments from 50% to 95%. As a result, the maximum equivalent (von Mises) stress for the parking brake lever is 230,29 MPa, and for the ratchet is 11,559 MPa. The maximum total deformation value for the brake lever is 0,95853 mm and for the ratchet is 0,0079482 mm. The parking brake lever mass decreased by 18,48% from 0.27751 kg to 0.22622 kg. The ratchet mass decreased from 0.095042 kg to 0.061911 kg by 34.85%.

Material Optimization in Formula One Seat Fit Based on Structural and Biomechanical Analysis

F1 drivers have reported that they suffer a long-term lower back pain due to ‘Porpoising’ effect, it is a series of bounce that is generated due to Aerodynamic downforce. This downforce is part of drag reduction principle that pulls the air underneath the vehicle, thereby creating an incredible speed of 200 to 230 mph. Also at 200 mph speed, the driver experiences a high amount G-forces up to six times during the race. This can be simply avoided by increasing the ground clearance of vehicle but at the same time it also reduces the max speed of the vehicle. Hence, without compromising the speed, Design optimization is done for driver’s seat-fit through Computational methods of Biomechanical modelling and simulation for determining the optimum Seat Angle for Postural Ergonomics. As an additional Reinforcement and Shock absorption in seat material to protect driver’s spine from the resulting dynamics, Material optimization is done by selecting Graphene as the suitable material over the existing Carbon fiber material. Finite element method was carried out for structural analysis of seat-fit model. The stress, strain and deformation values were found to be lesser in Graphene model when compared to Carbon fiber. The simulation results will provide a solution for eliminating the higher risk of spine injury or pathological condition of a sportsman and thereby improves the sporting performance. Key Word: Motorsports, Computational Biomechanics, Ergonomics, Design optimization, Material optimization, Finite element analysis, Spine Injury prevention

Age- and Sex-Specific MR-Feature Tracking Reference Values of Right Atrial Deformation in Healthy Adults.

Although right atrial (RA) myocardial deformation has important implications for patient diagnosis, prognosis, and risk stratification, its implementation in clinical practice has been hampered by limited normal reference values, especially in Asian populations. To establish age- and sex-specific reference values for RA strain, strain rate (SR), and displacement based on a large sample of healthy Chinese adults using MR-feature tracking (MR-FT). Retrospective. 524 healthy Chinese adults (287 male; mean age 43.7 ± 11.9 years). 1.5T/balanced steady-state free precession. RA deformation parameters, including reservoir, conduit, and booster strain (εs, εe, and εa), peak positive, early negative, and late negative SR (SRs, SRe, and SRa), and total, passive, and active displacement (Ds, De, and Da), were assessed using MR-FT. Student's t-test, one-way ANOVA, coefficients of determination (r2 ), intraclass correlation coefficients (ICC), and Bland-Altman plots. A P value <0.05 was considered significant. Women demonstrated significantly greater magnitudes of RA deformation parameters than men: εs (57.4% ± 15.1% vs. 44.3% ± 12.6%), εe (37.5% ± 13.4% vs. 27.4% ± 10.9%), εa (19.9% ± 5.7% vs. 16.9% ± 5.0%), SRs (2.62 ± 0.88 sec-1 vs. 2.00 ± 0.63 sec-1 ), SRe (-2.98 ± 1.26 sec-1 vs. -2.16 ± 0.92 sec-1 ), SRa (-2.28 ± 0.75 sec-1 vs. -1.84 ± 0.62 sec-1 ), Ds (-7.80 ± 1.90 mm vs. -7.46 ± 1.70 mm), and De (-4.84 ± 1.31 mm vs. -4.49 ± 1.21 mm). For both sexes, aging was significantly associated with decreased RA reservoir and conduit function (εs, SRs, Ds, εe, SRe, and De), and with increased εa and Da. RA deformation measurements had good to excellent intraobserver and interobserver reproducibility, with ICCs ranging from to 0.790 to 0.972. This study provides age- and sex-specific reference values of RA strain, SR, and displacement based on a large cohort of healthy Chinese adults using MR-FT. 3 TECHNICAL EFFICACY: Stage 2.

Static analysis of functionally graded porous beam-column frames by the complementary functions method

In this paper, an efficient and accurate numerical approach is implemented to examine the static behavior of Functionally Graded Porous (FGP) planar frames for the first time. The symmetric material constitutive relationship (SMCR), monotonic material constitutive relationships (MMCR), and uniform material constitutive relationship (UMCR) models are used to define the gradation of porosity along the thickness direction. The effects of porosity coefficient and material porosity distribution type on the static behavior of the FGP frames are investigated in detail. A direct relation between porosity coefficient and nodal deformations is observed.The effect of shear deformation is considered in the governing equations based on the Timoshenko Beam Theory (TBT). Within the scope of the presented procedure, fifth-order Runge-Kutta (RK5) algorithm is applied in the solution of the initial value problems. Imposing the rigidity matrix-based Complementary Functions Method (CFM) on the static analysis of the FGP planar frames is the novelty of this research. The results of the suggested approach are verified with the those of the finite element method (FEM), and those of the available literature. It has been carried out that type of the porosity distribution and porosity gradient index have an important impact on the response of FGP planar frames. By increasing the porosity coefficient, the displacement values of the frames made of UMCR and MMCR porosity distribution are affected more than those of the UMCR distributions. It can be noted that the SMCR can be preferred for designing the FGP beam-column structure as the minimum deformation values are obtained.

Feeling the Strain: Quantifying Ligand Deformation in Photosynthesis.

Structural distortion of protein-bound ligands can play a critical role in enzyme function by tuning the electronic and chemical properties of the ligand molecule. However, quantifying these effects is difficult due to the limited resolution of protein structures and the difficulty of generating accurate structural restraints for nonprotein ligands. Here, we seek to quantify these effects through a statistical analysis of ligand distortion in chlorophyll proteins (CP), where ring deformation is thought to play a role in energy and electron transfer. To assess the accuracy of ring-deformation estimates from available structural data, we take advantage of the C2 symmetry of photosystem II (PSII), comparing ring-deformation estimates for equivalent sites both within and between 113 distinct X-ray and cryogenic electron microscopy PSII structures. Significantly, we find that several deformation modes exhibit considerable variability in predictions, even for equivalent monomers, down to a 2 Å resolution, to an extent that probably prevents their utilization in optical calculations. We further find that refinement restraints play a critical role in determining deformation values to resolution as low as 2 Å. However, for those modes that are well-resolved in the structural data, ring deformation in PSII is strongly conserved across all species tested from cyanobacteria to algae. These results highlight both the opportunities and limitations inherent in structure-based analyses of the bioenergetic and optical properties of CPs and other protein-ligand complexes.