Background Serial sarcomere number(SSN)critically influences muscle function and is hypothesized to protect against injury.While most evidence for SSN addition comes from non-human animal studies,eccentric exercise is...Background Serial sarcomere number(SSN)critically influences muscle function and is hypothesized to protect against injury.While most evidence for SSN addition comes from non-human animal studies,eccentric exercise is often proposed as a key stimulus due to its association with increased fascicle length in humans.However,the most efficient exercise stimuli and the effectiveness of eccentric training in increasing SSN remain unclear.The objective of this study was to provide a detailed historical overview of research exploring the mechanical factors regulating muscle/fiber length and its relationship with function,and to explore more recent evidence that eccentric muscle contractions might be an important stimulus for SSN regulation using a meta-analytic approach.Methods An extensive literature search with snowballing was conducted to build the historical review.A systematic review with random-effect meta analyses was performed to compare proposed types of fiber-lengthening exercises to control conditions.Results The historical review demonstrated that the application of forces at long fiber lengths,but not specifically the use of greater excursions,plays an important role in increasing SSN.Animal data showed changes in SSN exceeding 20%over several weeks with varied forms of activities.Nonetheless,the meta-analysis revealed a lack of effect of eccentric resistance training in animal models(Δ=1%;Cohen’s d=0.19(95%confidence interval:–0.29 to 0.67),p=0.449).Conclusion High active or passive muscle forces applied at long fiber lengths appear to be the key stimuli triggering sarcomerogenesis.Eccentric exercise does not seem to be a key promoter of SSN.Too few studies exist to draw conclusions as to the effect of eccentric exercise on SSN in humans.Understanding the mechanical triggers and physiological mechanisms involved in serial sarcomere addition could help in the development of exercise(and other)interventions to optimize muscle function and reduce injury risk.展开更多
The first in vivo measurements of serial sarcomere number in human muscles before and after eccentric strength training have just been published and the results will interest anyone involved with sport or health:Train...The first in vivo measurements of serial sarcomere number in human muscles before and after eccentric strength training have just been published and the results will interest anyone involved with sport or health:Training the hamstrings 3 times per week for 9 weeks with the Nordic hamstring exercise was found to increase the number of sarcomeres in series in the biceps femoris long head(BFlh)by≥25%.1 In this commentary,we highlight an additional,paradoxical finding,which was not discussed by the authors;namely that the substantial serial sarcomere addition must have been accompanied by a subtraction of sarcomeres in parallel to match the relatively small increase in muscle volume after training.展开更多
Sarcomerogenesis,the addition of serial sarcomeres in skeletal muscle myofibrils and fibres,is a natural occurrence during growth and maturation of animals,including humans.However,the detailed mechanisms that allow f...Sarcomerogenesis,the addition of serial sarcomeres in skeletal muscle myofibrils and fibres,is a natural occurrence during growth and maturation of animals,including humans.However,the detailed mechanisms that allow for sarcomerogenesis are not fully understood.In some diseases,such as cerebral palsy in children,sarcomerogenesis appears to be inhibited or at least reduced,1,2 often causing severe restrictions in muscle and joint function.展开更多
The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and run...The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and running resistance,and the dynamic models of gear transmission system are not sufficiently comprehensive.This paper aims to establish an electromechanical coupling dynamic model of HST traction transmission system and study its electromechanical coupling vibration characteristics,in which the internal excitation factors such as gear eccentricity,time-varying meshing stiffness,backlash,meshing error,and external excitation factors such as electromagnetic torque and running resistance are stressed.The research results indicate that gear eccentricity and running resistance have a significant impact on the stability of the system,and gear eccentricity leads to intensified system vibration and decreased anti-interference ability.In addition,the characteristic frequency of gear eccentricity can be extracted from mechanical signals and current signals as a preliminary basis for eccentricity detection,and electrical signals can also be used to monitor changes in train running resistance in real time.The results of this study provide some useful insights into designing dynamic performance parameters for HST transmission systems and monitoring train operational states.展开更多
This paper deals with the bearing capacity determination of strip footing on a rock mass in hilly area by considering the influence of inclined and eccentric loading. Applying the generalized HoekBrown failure criteri...This paper deals with the bearing capacity determination of strip footing on a rock mass in hilly area by considering the influence of inclined and eccentric loading. Applying the generalized HoekBrown failure criterion, the failure behavior of the rock mass is modeled with the help of the power cone programming in the lower bound finite element limit analysis framework. Using bearing capacity factor(Ns), the change in bearing capacity of the strip footing due to the occurrence of eccentrically inclined loading is presented. The variations of the magnitude of Ns are obtained by examining the effects of the Hoek-Brown rock mass strength parameters(uniaxial compressive strength(sci), disturbance factor(D), rock parameter(mi), and Geological Strength Index(GSI)) in the presence of different magnitudes of eccentricity(e) and inclination angle(λ) with respect to the vertical plane, and presented as design charts. Both the inclined loading modes, i.e., inclination towards the center of strip footing(+λ) and inclination away from the center of strip footing(-λ), are adopted to perform the investigation. In addition, the correlation between the input parameters and the corresponding output is developed by utilizing the artificial neural network(ANN). Additionally, from sensitivity analysis, it is observed that inclination angle(λ) is the most sensitive parameter. For practicing engineers, the obtained design equation and design charts can be beneficial to understand the bearing capacity variation in the existence of eccentrically inclined loading in mountain areas.展开更多
In visual measurement,high-precision camera calibration often employs circular targets.To address issues in mainstream methods,such as the eccentricity error of the circle from using the circle’s center for calibrati...In visual measurement,high-precision camera calibration often employs circular targets.To address issues in mainstream methods,such as the eccentricity error of the circle from using the circle’s center for calibration,overfitting or local minimum from fullparameter optimization,and calibration errors due to neglecting the center of distortion,a stepwise camera calibration method incorporating compensation for eccentricity error was proposed to enhance monocular camera calibration precision.Initially,the multiimage distortion correction method calculated the common center of distortion and coefficients,improving precision,stability,and efficiency compared to single-image distortion correction methods.Subsequently,the projection point of the circle’s center was compared with the center of the contour’s projection to iteratively correct the eccentricity error,leading to more precise and stable calibration.Finally,nonlinear optimization refined the calibration parameters to minimize reprojection error and boosts precision.These processes achieved stepwise camera calibration,which enhanced robustness.In addition,the module comparison experiment showed that both the eccentricity error compensation and the camera parameter optimization could improve the calibration precision,but the latter had a greater impact.The combined use of the two methods further improved the precision and stability.Simulations and experiments confirmed that the proposed method achieved high precision,stability,and robustness,suitable for high-precision visual measurements.展开更多
A three-dimensional mathematical model coupling electromagnetic,flow,heat transfer,and solidification has been developed to investigate the effect of eccentric mold electromagnetic stirring(EM-EMS)on the flow and heat...A three-dimensional mathematical model coupling electromagnetic,flow,heat transfer,and solidification has been developed to investigate the effect of eccentric mold electromagnetic stirring(EM-EMS)on the flow and heat transfer of molten steel in round blooms with different cross sections.The uneven distribution of the flow field caused by EM-EMS was improved by changing the straight submerged entry nozzle(SEN)to a four-port SEN.The symmetry index was determined by the velocity distributions on the left and right sides of the center cross section of mold electromagnetic stirring(M-EMS),which quantitatively evaluated the symmetry of EM-EMS on the flow field.In the presence of EM-EMS,the maximum temperature difference ofϕ500 mm andϕ650 mm round blooms between the inner and outer curves amounted to 63 and 26 K,respectively.The maximum distinction between the solidified shells in the inner and outer curves was 11.5 and 5.3 mm,respectively.After using the four-port SEN,the temperature and the shell distribution on the inner and outer curves for theϕ500 mm round bloom were almost the same.The symmetry indices ofϕ500 mm andϕ650 mm round blooms were increased from 0.55 and 0.70 to 0.77 and 0.87,respectively.The four-port SEN can be used to mitigate the negative impact of EM-EMS on the steel flow field.展开更多
A microannulus(MA) is the primary reason for sustained casing pressure in multi-stage fractured-shale gas wells. However, the effect of the casing eccentricity on the long horizontal section has not been considered. I...A microannulus(MA) is the primary reason for sustained casing pressure in multi-stage fractured-shale gas wells. However, the effect of the casing eccentricity on the long horizontal section has not been considered. In this study, a full-scale integrity tester for cement sheaths is adopted to measure the cumulative plastic deformation. Numerical models are applied to evaluate the development of the cumulative plastic deformation and quantify the MA width considering casing centralization and eccentricity in the context of multiple loading and unloading cycles. Subsequently, the influences of the eccentricity distance and angle, cement-sheath mechanical variables, and different well depths on the cumulative sheath plastic deformation and sheath MA development are explored. The research results demonstrate that casing eccentricity significantly increases the cumulative sheath plastic deformation compared with that of the casing-centered condition. Consequently, the risk of sealing integrity failure increases. The accumulated plastic deformation increases when the eccentricity distance increases. In contrast, the initial plastic deformation increases as the eccentricity angle increases. However, the cumulative plastic deformation decreases after a specific loading and unloading cycle count. Affected by the coupled influence of the internal casing pressure and fracturing stages, the width of the MA in the horizontal section increased from the toe to the heel, and the casing eccentricity significantly increased the MA width at each stage, thus increasing the risk of gas channeling. Finally, an engineering case is considered to study the influence of casing eccentricity. The results show that cement slurries that form low and high elastic moduli can be applied to form a cement sheath when the fracturing stage is lower or higher than a specific value, respectively. The results of this study offer theoretical references and engineering support for the integrity control of cement sheath sealing.展开更多
This study focuses on variations in the hysteretic behavior of buckling-restrained braces(BRBs)configured with or without out-of-plane eccentricity under cyclic loading.Quasi-static experiments and numerical simulatio...This study focuses on variations in the hysteretic behavior of buckling-restrained braces(BRBs)configured with or without out-of-plane eccentricity under cyclic loading.Quasi-static experiments and numerical simulations were carried out on concentrically and eccentrically loaded BRB specimens to investigate the mechanical properties,energy dissipation performance,stress distribution,and high-order deformation pattern.The experimental and numerical results showed that compared to the concentrically loaded BRBs,the stiffness,yield force,cumulated plastic ductility(CPD)coefficient,equivalent viscous damping coefficient and energy dissipation decreased,and the yield displacement and compression strength adjustment factor increased for the eccentrically loaded BRBs.With the existence of the out-of-plane eccentricity,the initial yield position changes from the yield segment to the junction between the yield segment and transition segment under a tensile load,while the initial high-order buckling pattern changes from a first-order C-shape to a secondorder S-shape under a compressive load.展开更多
A novel three-dimensional numerical model is proposed to investigate the effect of tool eccentricity on the coupled thermal and material flow characteristics in friction stir welding(FSW) process.An asymmetrical bound...A novel three-dimensional numerical model is proposed to investigate the effect of tool eccentricity on the coupled thermal and material flow characteristics in friction stir welding(FSW) process.An asymmetrical boundary condition at the tool-workpiece interface,and the dynamic mesh technique are both employed for the consideration of the tool eccentricity during tool rotating.It is found that tool eccentricity induces the periodical variation of the heat densities both at the tool-workpiece interface and inside the shear layer,but the fluctuation amplitudes of the heat density variations are limited.However,it is demonstrated that tool eccentricity results in significant variation of the material flow behavior in one tool rotating period.Moreover,the material velocity variation at the retreating side is particularly important for the formation of the periodic characteristics in FSW.The modeling result is found to be in good agreement with the experimental one.展开更多
The main purpose of this paper is to investigate the effect of core eccentricity on the structural behavior of concrete tall buildings.Concrete buildings of 55 floors with plan dimensions 48.0×48.0 m2 were invest...The main purpose of this paper is to investigate the effect of core eccentricity on the structural behavior of concrete tall buildings.Concrete buildings of 55 floors with plan dimensions 48.0×48.0 m2 were investigated.Three cases of main core locations are studied:centric(A),eccentric by one sixth(B)and one third(C)of building width.The three-dimensional finite element method has been used in conducting structural analysis through ETABS software.Gravity and lateral(wind and seismic)loadings are applied to all building cases.It has been concluded that the core location is the prime parameter governing the structural behavior of tall buildings.Although the first two cases(A,B)have acceptable and similar structural behaviors conforming to code limits,in the third case(C),the building behavior came beyond code limits.The author introduced remedial action by adding two secondary cores in the opposite direction of the main core(C-R)to restore the building behavior to the code limits.The results of this action were satisfactory.展开更多
Regarding the Chan Buddhism lamp records from the Song Dynasty and starting from Jing De Zhuan Deng Lu,the category of“enlightened masters in Chan Buddhism”禪門達者was listed separately,meaning a separate category w...Regarding the Chan Buddhism lamp records from the Song Dynasty and starting from Jing De Zhuan Deng Lu,the category of“enlightened masters in Chan Buddhism”禪門達者was listed separately,meaning a separate category was established for eccentric monks who pretended to be crazy,had unknown inheritance and miraculous deeds,and were difficult to classify.The following lamp records named this category of eccentric monks as“sages”散聖,or“saints”應化聖賢,which constructed another historical genealogy for the special Chan Buddhism eccentric monks.Moreover,the early lamp records included mostly idiosyncratic mad monks from previous dynasties.Since the Southern Song Dynasty,Chan Buddhism historical materials included many sages from the current dynasty.Therefore,this study mainly examines how the genealogy of Chan Buddhism eccentric monks was constructed in Song Dynasty Chan Buddhism lamp records,including quotations,and organizes the images of eccentric monks in the Song Dynasty,as written in Chan Buddhism historical materials,in order that the meaning of existence of these enlightened masters,sages,saints,etc.,included in the genealogy of Song Dynasty eccentric monks in the history of Chan Buddhism can be reflected.展开更多
Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for...Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for achieving an excellent smooth blasting effect.In this paper,the Riedel-Hiermaier-Thoma(RHT)model was employed to study rock mass damage under smooth blasting.Firstly,the parameters of the RHT model were calibrated by using the existing SHPB experiment,which were then verified by the existing blasting experiment results.Secondly,the influence of different charge structures on the blasting effect was investigated using the RHT model.The simulation results indicated that eccentric charge blasting has an obvious pressure eccentricity effect.Finally,to improve the blasting effect,the smooth blasting parameters were optimized based on an eccentric charge structure.The overbreak and underbreak phenomena were effectively controlled,and a good blasting effect was achieved with the optimized blasting parameters.展开更多
The eccentric-gear can be used for variable speed transmission.But,due to the vibrations caused by variation of backlash in working process,the eccentric-gear is seldom applied in engineering project.There is just a l...The eccentric-gear can be used for variable speed transmission.But,due to the vibrations caused by variation of backlash in working process,the eccentric-gear is seldom applied in engineering project.There is just a little study about the eccentric-gear.And it is necessary to take a further research on eccentric-gear transmission for the applications in the transplanting mechanism of high-speed rice transplanter.The key of this paper is to extend understanding of three following characteristics of this drive：（1） The rotation-center-distance and the geometrical-center-distance of the two meshing eccentric gears are respectively the hypotenuse and the straight edge of a right triangle in a cycle.（2） The geometrical center line of two meshing gears divides the linking-line of the two rotational centers equally.（3） When two times the eccentricity of gear,the rotation-center-distance and the geometrical-center-distance form a right triangle,the optimal value of rotation-center-distance can be determined.In addition,the kinematic analysis,such as the relationship between contact point and midpoint of the linking-line of two gears＇ rotational centers,transmission ratio between the driving-gear and the driven-gear,contact angle and coordinate of contact point are be made,further the formula for calculation of contact force,flow chart for writing optimization program and curve for analysis of data are also be developed.The relationship between the rotation-center-distance and the geometrical-center-distance,which is determined by three characteristics mentioned above, is a key for the rational design and application of eccentric-gear transmission.Particularly,the presented right triangle property of eccentric gear drive is an important reference for effective analysis of dynamic characteristic of eccentric-gear mechanism and its reliable design.展开更多
The spatial structure of the velocity field in a stirred vessel with water has been measured and analyzed using the laser Doppler velocimeter technique, with the immersing depth and agitation speed of the impeller re-...The spatial structure of the velocity field in a stirred vessel with water has been measured and analyzed using the laser Doppler velocimeter technique, with the immersing depth and agitation speed of the impeller re-maining approximately constant. The experimental results were provided such as the mean velocity field, fluctuat-ing velocities, turbulent kinetic energy, Reynolds shear stress and time series of the velocity in the stirred tank. These results probably provided the valuable basis to further optimize and enlarge the stirred tank in the industrial process.展开更多
The anchoring eccentricity of the bolt and cable bolt is a common problem in geotechnical support engineering and affects the ability of the bolt and cable bolt to control the rock mass to a certain extent.This paper ...The anchoring eccentricity of the bolt and cable bolt is a common problem in geotechnical support engineering and affects the ability of the bolt and cable bolt to control the rock mass to a certain extent.This paper reports on numerical simulation and laboratory experiments conducted to clarify the effect of eccentricity on the anchoring quality of the bolt and cable bolt,and to establish an effective solution strategy.The results reveal that the anchoring eccentricity causes unbalanced stress distribution and the uncoordinated deformation of the resin layer,which results in higher stress and greater deformation of the resin layer at the near side of the rod body.Additionally,as the degree of anchoring eccentricity increases,the effect becomes more significant,and the resin layer of the anchoring system becomes more likely to undergo preferential failure locally,which weakens the load-bearing performance of the anchoring system.This paper develops an innovative bolt anchoring rectifying device(B-ARD)and cable bolt anchoring rectifying device(C-ARD)on the basis of the structural characteristics of the bolt and cable bolt to better ensure the anchoring effect of them.The working effects of these two devices were verified in detailed experiments and analysis.The experimental results show that the anchoring rectifying devices(ARD)improve and ensure the anchoring concentricity of the bolt and cable bolt,which will help improve the supporting performance of them.The paper provides a convenient and effective method for improving the anchoring concentricity of the bolt and cable bolt,and provides a concept and reference for technical research on improving the effect of roof bolting.展开更多
In this paper, the numerical predictions of 3D hydrodynamics and power consumption in a vessel stirred by mul- tiple eccentrically located impellers are presented. The vessel is a fiat-bottomed cylindrical one equippe...In this paper, the numerical predictions of 3D hydrodynamics and power consumption in a vessel stirred by mul- tiple eccentrically located impellers are presented. The vessel is a fiat-bottomed cylindrical one equipped with six-curved bladed impellers. Aqueous solutions of xanthan gum are used, which have a shear thinning behavior with yield stress. The influence of several parameters on the mixing efficiency has been investigated, namely： the stirring rate, fluid theology, impeller number and impeller clearance from the tank bottom. Our predicted results are compared with other experimental data and a satisfactory agreement is found.展开更多
Induction motors （IMs） are commonly used in various industrial applications. To improve energy con- sumption efficiency, a reliable IM health condition moni- toring system is very useful to detect IM fault at its ea...Induction motors （IMs） are commonly used in various industrial applications. To improve energy con- sumption efficiency, a reliable IM health condition moni- toring system is very useful to detect IM fault at its earliest stage to prevent operation degradation, and malfunction of IMs. An intelligent harmonic synthesis technique is pro- posed in this work to conduct incipient air-gap eccentricity fault detection in IMs. The fault harmonic series are syn- thesized to enhance fault features. Fault related local spectra are processed to derive fault indicators for IM air- gap eccentricity diagnosis. The effectiveness of the pro- posed harmonic synthesis technique is examined experi- mentally by IMs with static air-gap eccentricity and dynamic air-gap eccentricity states under different load conditions. Test results show that the developed harmonic synthesis technique can extract fault features effectively for initial IM air-gap eccentricity fault detection.展开更多
In gas injection refining processes, a great amount of gas is injected into molten metal in short time, so that very large bubbles are inevitably formed. Wide dispersion of small bubbles in the bath is indispensable f...In gas injection refining processes, a great amount of gas is injected into molten metal in short time, so that very large bubbles are inevitably formed. Wide dispersion of small bubbles in the bath is indispensable for high refining efficiency. Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion. Absorption rate are used to research on the influence law of the bubble dispersion and disintegration and gas-liquid absorption by the influence of, rotation mode, rotation speed and gas flow rate. Compared to the experimental results of absorption rate under eccentric stirring and centric stirring ,provide the scientific experimental and theoretical guidance for high-temperature experiment of hot metal desulfurization .According to experimental and theoretical analysis, this paper has studied various factors effecting on gas absorption process and volumetric mass transfer coefficient using the system of CO2-NaOH-H2O.The results show that:the volumetric mass transfer coefficient and absorption efficiency of CO2 can be increased under eccentric stirring mode, Because bubble disperse quickly with eccentric mechanical stirring, which results in promoting complete reaction between CO2 and NaOH, and improving the mass transfer coefficient and absorption. Volumetric mass transfer coefficient and efficiency of CO2 increase with the increasing rotation speed under the condition of eccentric stirring .But volumetric mass transfer coefficient and efficiency of CO2 decrease with the increasing rotation speed under the condition of centric stirring.展开更多
The location and geometry of large-scale asperity present at the foundation of concrete gravity dams and buttress dams affect the shear resistance of the concrete-rock interface.However,the parameters describing the f...The location and geometry of large-scale asperity present at the foundation of concrete gravity dams and buttress dams affect the shear resistance of the concrete-rock interface.However,the parameters describing the frictional resistance of the interface usually do not account for these asperities.This could result in an underestimate of the peak shear stre ngth,which leads to significantly conservative design for new dams or unnecessary stability enhancing measures for existing ones.The aim of this work was to investigate the effect of the location of first-order asperity on the peak shear strength of a concrete-rock interface under eccentric load and the model discrepancy associated with the commonly used rigid body methods for calculating the factor of safety(FS)against sliding.For this,a series of direct and eccentric shear tests under constant normal load(CNL)was carried out on concrete-rock samples.The peak shear strengths measured in the tests were compared in terms of asperity location and with the predicted values from analytical rigid body methods.The results showed that the large-scale asperity under eccentric load significantly affected the peak shear strength.Furthermore,unlike the conventional assumption of sliding or shear failure of an asperity in direct shear,under the effect of eccentric shear load,a tensile failure in the rock or in the concrete could occur,resulting in a lower shear strength compared with that of direct shear tests.These results could have important implications for assessment of the FS against sliding failure in the concrete-rock interface.展开更多
文摘Background Serial sarcomere number(SSN)critically influences muscle function and is hypothesized to protect against injury.While most evidence for SSN addition comes from non-human animal studies,eccentric exercise is often proposed as a key stimulus due to its association with increased fascicle length in humans.However,the most efficient exercise stimuli and the effectiveness of eccentric training in increasing SSN remain unclear.The objective of this study was to provide a detailed historical overview of research exploring the mechanical factors regulating muscle/fiber length and its relationship with function,and to explore more recent evidence that eccentric muscle contractions might be an important stimulus for SSN regulation using a meta-analytic approach.Methods An extensive literature search with snowballing was conducted to build the historical review.A systematic review with random-effect meta analyses was performed to compare proposed types of fiber-lengthening exercises to control conditions.Results The historical review demonstrated that the application of forces at long fiber lengths,but not specifically the use of greater excursions,plays an important role in increasing SSN.Animal data showed changes in SSN exceeding 20%over several weeks with varied forms of activities.Nonetheless,the meta-analysis revealed a lack of effect of eccentric resistance training in animal models(Δ=1%;Cohen’s d=0.19(95%confidence interval:–0.29 to 0.67),p=0.449).Conclusion High active or passive muscle forces applied at long fiber lengths appear to be the key stimuli triggering sarcomerogenesis.Eccentric exercise does not seem to be a key promoter of SSN.Too few studies exist to draw conclusions as to the effect of eccentric exercise on SSN in humans.Understanding the mechanical triggers and physiological mechanisms involved in serial sarcomere addition could help in the development of exercise(and other)interventions to optimize muscle function and reduce injury risk.
文摘The first in vivo measurements of serial sarcomere number in human muscles before and after eccentric strength training have just been published and the results will interest anyone involved with sport or health:Training the hamstrings 3 times per week for 9 weeks with the Nordic hamstring exercise was found to increase the number of sarcomeres in series in the biceps femoris long head(BFlh)by≥25%.1 In this commentary,we highlight an additional,paradoxical finding,which was not discussed by the authors;namely that the substantial serial sarcomere addition must have been accompanied by a subtraction of sarcomeres in parallel to match the relatively small increase in muscle volume after training.
文摘Sarcomerogenesis,the addition of serial sarcomeres in skeletal muscle myofibrils and fibres,is a natural occurrence during growth and maturation of animals,including humans.However,the detailed mechanisms that allow for sarcomerogenesis are not fully understood.In some diseases,such as cerebral palsy in children,sarcomerogenesis appears to be inhibited or at least reduced,1,2 often causing severe restrictions in muscle and joint function.
基金supported by Sichuan Science and Technology Program(Grant No.2020YFH0080)the National Natural Science Foundation of China(Grant No.51475386)the National Basic Research Project of China(973 Program,Grant No.2015CB654801).
文摘The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and running resistance,and the dynamic models of gear transmission system are not sufficiently comprehensive.This paper aims to establish an electromechanical coupling dynamic model of HST traction transmission system and study its electromechanical coupling vibration characteristics,in which the internal excitation factors such as gear eccentricity,time-varying meshing stiffness,backlash,meshing error,and external excitation factors such as electromagnetic torque and running resistance are stressed.The research results indicate that gear eccentricity and running resistance have a significant impact on the stability of the system,and gear eccentricity leads to intensified system vibration and decreased anti-interference ability.In addition,the characteristic frequency of gear eccentricity can be extracted from mechanical signals and current signals as a preliminary basis for eccentricity detection,and electrical signals can also be used to monitor changes in train running resistance in real time.The results of this study provide some useful insights into designing dynamic performance parameters for HST transmission systems and monitoring train operational states.
基金supported by Centre for Development of Advanced Computing (CDAC), Pune。
文摘This paper deals with the bearing capacity determination of strip footing on a rock mass in hilly area by considering the influence of inclined and eccentric loading. Applying the generalized HoekBrown failure criterion, the failure behavior of the rock mass is modeled with the help of the power cone programming in the lower bound finite element limit analysis framework. Using bearing capacity factor(Ns), the change in bearing capacity of the strip footing due to the occurrence of eccentrically inclined loading is presented. The variations of the magnitude of Ns are obtained by examining the effects of the Hoek-Brown rock mass strength parameters(uniaxial compressive strength(sci), disturbance factor(D), rock parameter(mi), and Geological Strength Index(GSI)) in the presence of different magnitudes of eccentricity(e) and inclination angle(λ) with respect to the vertical plane, and presented as design charts. Both the inclined loading modes, i.e., inclination towards the center of strip footing(+λ) and inclination away from the center of strip footing(-λ), are adopted to perform the investigation. In addition, the correlation between the input parameters and the corresponding output is developed by utilizing the artificial neural network(ANN). Additionally, from sensitivity analysis, it is observed that inclination angle(λ) is the most sensitive parameter. For practicing engineers, the obtained design equation and design charts can be beneficial to understand the bearing capacity variation in the existence of eccentrically inclined loading in mountain areas.
文摘In visual measurement,high-precision camera calibration often employs circular targets.To address issues in mainstream methods,such as the eccentricity error of the circle from using the circle’s center for calibration,overfitting or local minimum from fullparameter optimization,and calibration errors due to neglecting the center of distortion,a stepwise camera calibration method incorporating compensation for eccentricity error was proposed to enhance monocular camera calibration precision.Initially,the multiimage distortion correction method calculated the common center of distortion and coefficients,improving precision,stability,and efficiency compared to single-image distortion correction methods.Subsequently,the projection point of the circle’s center was compared with the center of the contour’s projection to iteratively correct the eccentricity error,leading to more precise and stable calibration.Finally,nonlinear optimization refined the calibration parameters to minimize reprojection error and boosts precision.These processes achieved stepwise camera calibration,which enhanced robustness.In addition,the module comparison experiment showed that both the eccentricity error compensation and the camera parameter optimization could improve the calibration precision,but the latter had a greater impact.The combined use of the two methods further improved the precision and stability.Simulations and experiments confirmed that the proposed method achieved high precision,stability,and robustness,suitable for high-precision visual measurements.
基金supported by the National Natural Science Foundation of China(No.52074207).
文摘A three-dimensional mathematical model coupling electromagnetic,flow,heat transfer,and solidification has been developed to investigate the effect of eccentric mold electromagnetic stirring(EM-EMS)on the flow and heat transfer of molten steel in round blooms with different cross sections.The uneven distribution of the flow field caused by EM-EMS was improved by changing the straight submerged entry nozzle(SEN)to a four-port SEN.The symmetry index was determined by the velocity distributions on the left and right sides of the center cross section of mold electromagnetic stirring(M-EMS),which quantitatively evaluated the symmetry of EM-EMS on the flow field.In the presence of EM-EMS,the maximum temperature difference ofϕ500 mm andϕ650 mm round blooms between the inner and outer curves amounted to 63 and 26 K,respectively.The maximum distinction between the solidified shells in the inner and outer curves was 11.5 and 5.3 mm,respectively.After using the four-port SEN,the temperature and the shell distribution on the inner and outer curves for theϕ500 mm round bloom were almost the same.The symmetry indices ofϕ500 mm andϕ650 mm round blooms were increased from 0.55 and 0.70 to 0.77 and 0.87,respectively.The four-port SEN can be used to mitigate the negative impact of EM-EMS on the steel flow field.
基金financially supported by the National Natural Science Foundation of China (Grant No. 52374001, No. 52004013)。
文摘A microannulus(MA) is the primary reason for sustained casing pressure in multi-stage fractured-shale gas wells. However, the effect of the casing eccentricity on the long horizontal section has not been considered. In this study, a full-scale integrity tester for cement sheaths is adopted to measure the cumulative plastic deformation. Numerical models are applied to evaluate the development of the cumulative plastic deformation and quantify the MA width considering casing centralization and eccentricity in the context of multiple loading and unloading cycles. Subsequently, the influences of the eccentricity distance and angle, cement-sheath mechanical variables, and different well depths on the cumulative sheath plastic deformation and sheath MA development are explored. The research results demonstrate that casing eccentricity significantly increases the cumulative sheath plastic deformation compared with that of the casing-centered condition. Consequently, the risk of sealing integrity failure increases. The accumulated plastic deformation increases when the eccentricity distance increases. In contrast, the initial plastic deformation increases as the eccentricity angle increases. However, the cumulative plastic deformation decreases after a specific loading and unloading cycle count. Affected by the coupled influence of the internal casing pressure and fracturing stages, the width of the MA in the horizontal section increased from the toe to the heel, and the casing eccentricity significantly increased the MA width at each stage, thus increasing the risk of gas channeling. Finally, an engineering case is considered to study the influence of casing eccentricity. The results show that cement slurries that form low and high elastic moduli can be applied to form a cement sheath when the fracturing stage is lower or higher than a specific value, respectively. The results of this study offer theoretical references and engineering support for the integrity control of cement sheath sealing.
基金National Natural Science Foundation of China under Grant No.51978184。
文摘This study focuses on variations in the hysteretic behavior of buckling-restrained braces(BRBs)configured with or without out-of-plane eccentricity under cyclic loading.Quasi-static experiments and numerical simulations were carried out on concentrically and eccentrically loaded BRB specimens to investigate the mechanical properties,energy dissipation performance,stress distribution,and high-order deformation pattern.The experimental and numerical results showed that compared to the concentrically loaded BRBs,the stiffness,yield force,cumulated plastic ductility(CPD)coefficient,equivalent viscous damping coefficient and energy dissipation decreased,and the yield displacement and compression strength adjustment factor increased for the eccentrically loaded BRBs.With the existence of the out-of-plane eccentricity,the initial yield position changes from the yield segment to the junction between the yield segment and transition segment under a tensile load,while the initial high-order buckling pattern changes from a first-order C-shape to a secondorder S-shape under a compressive load.
基金the financial support from the National Natural Science Foundation of China (Nos. 52005297, 52035005)the Key Research and Development Program of Shandong Province, China (No. 2021ZLGX01)。
文摘A novel three-dimensional numerical model is proposed to investigate the effect of tool eccentricity on the coupled thermal and material flow characteristics in friction stir welding(FSW) process.An asymmetrical boundary condition at the tool-workpiece interface,and the dynamic mesh technique are both employed for the consideration of the tool eccentricity during tool rotating.It is found that tool eccentricity induces the periodical variation of the heat densities both at the tool-workpiece interface and inside the shear layer,but the fluctuation amplitudes of the heat density variations are limited.However,it is demonstrated that tool eccentricity results in significant variation of the material flow behavior in one tool rotating period.Moreover,the material velocity variation at the retreating side is particularly important for the formation of the periodic characteristics in FSW.The modeling result is found to be in good agreement with the experimental one.
文摘The main purpose of this paper is to investigate the effect of core eccentricity on the structural behavior of concrete tall buildings.Concrete buildings of 55 floors with plan dimensions 48.0×48.0 m2 were investigated.Three cases of main core locations are studied:centric(A),eccentric by one sixth(B)and one third(C)of building width.The three-dimensional finite element method has been used in conducting structural analysis through ETABS software.Gravity and lateral(wind and seismic)loadings are applied to all building cases.It has been concluded that the core location is the prime parameter governing the structural behavior of tall buildings.Although the first two cases(A,B)have acceptable and similar structural behaviors conforming to code limits,in the third case(C),the building behavior came beyond code limits.The author introduced remedial action by adding two secondary cores in the opposite direction of the main core(C-R)to restore the building behavior to the code limits.The results of this action were satisfactory.
文摘Regarding the Chan Buddhism lamp records from the Song Dynasty and starting from Jing De Zhuan Deng Lu,the category of“enlightened masters in Chan Buddhism”禪門達者was listed separately,meaning a separate category was established for eccentric monks who pretended to be crazy,had unknown inheritance and miraculous deeds,and were difficult to classify.The following lamp records named this category of eccentric monks as“sages”散聖,or“saints”應化聖賢,which constructed another historical genealogy for the special Chan Buddhism eccentric monks.Moreover,the early lamp records included mostly idiosyncratic mad monks from previous dynasties.Since the Southern Song Dynasty,Chan Buddhism historical materials included many sages from the current dynasty.Therefore,this study mainly examines how the genealogy of Chan Buddhism eccentric monks was constructed in Song Dynasty Chan Buddhism lamp records,including quotations,and organizes the images of eccentric monks in the Song Dynasty,as written in Chan Buddhism historical materials,in order that the meaning of existence of these enlightened masters,sages,saints,etc.,included in the genealogy of Song Dynasty eccentric monks in the history of Chan Buddhism can be reflected.
基金Projects(11802058,52074262)supported by the National Natural Science Foundation of ChinaProjects(BK20170670,BK20180651)supported by the Jiangsu Youth Foundation,China+2 种基金Project(2020QN06)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(SKLGDUEK1803)supported by the State Key Laboratory for Geomechanics and Deep Underground Engineering,ChinaProject supported by the Mass Entrepreneurship and Innovation Project of Jiangsu,China。
文摘Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for achieving an excellent smooth blasting effect.In this paper,the Riedel-Hiermaier-Thoma(RHT)model was employed to study rock mass damage under smooth blasting.Firstly,the parameters of the RHT model were calibrated by using the existing SHPB experiment,which were then verified by the existing blasting experiment results.Secondly,the influence of different charge structures on the blasting effect was investigated using the RHT model.The simulation results indicated that eccentric charge blasting has an obvious pressure eccentricity effect.Finally,to improve the blasting effect,the smooth blasting parameters were optimized based on an eccentric charge structure.The overbreak and underbreak phenomena were effectively controlled,and a good blasting effect was achieved with the optimized blasting parameters.
基金supported by National Basic Research Program of China (973 Program,Grant No.2004CCA05700)National Natural Science Foundation of China(Grant No.50875244)Zhejiang Provincial Natural Science Foundation of China(Grant No.Z105706)
文摘The eccentric-gear can be used for variable speed transmission.But,due to the vibrations caused by variation of backlash in working process,the eccentric-gear is seldom applied in engineering project.There is just a little study about the eccentric-gear.And it is necessary to take a further research on eccentric-gear transmission for the applications in the transplanting mechanism of high-speed rice transplanter.The key of this paper is to extend understanding of three following characteristics of this drive：（1） The rotation-center-distance and the geometrical-center-distance of the two meshing eccentric gears are respectively the hypotenuse and the straight edge of a right triangle in a cycle.（2） The geometrical center line of two meshing gears divides the linking-line of the two rotational centers equally.（3） When two times the eccentricity of gear,the rotation-center-distance and the geometrical-center-distance form a right triangle,the optimal value of rotation-center-distance can be determined.In addition,the kinematic analysis,such as the relationship between contact point and midpoint of the linking-line of two gears＇ rotational centers,transmission ratio between the driving-gear and the driven-gear,contact angle and coordinate of contact point are be made,further the formula for calculation of contact force,flow chart for writing optimization program and curve for analysis of data are also be developed.The relationship between the rotation-center-distance and the geometrical-center-distance,which is determined by three characteristics mentioned above, is a key for the rational design and application of eccentric-gear transmission.Particularly,the presented right triangle property of eccentric gear drive is an important reference for effective analysis of dynamic characteristic of eccentric-gear mechanism and its reliable design.
基金Supported by the Natural Science Foundation of Inner Mongolia (No.200408020715).
文摘The spatial structure of the velocity field in a stirred vessel with water has been measured and analyzed using the laser Doppler velocimeter technique, with the immersing depth and agitation speed of the impeller re-maining approximately constant. The experimental results were provided such as the mean velocity field, fluctuat-ing velocities, turbulent kinetic energy, Reynolds shear stress and time series of the velocity in the stirred tank. These results probably provided the valuable basis to further optimize and enlarge the stirred tank in the industrial process.
基金This study was supported by the National Natural Science Foundation of China(No.52074102)Foundation for Distinguished Young Talents in Higher Education of Henan(No.212300410006)+1 种基金Foundation for the Science and Technology Innovation Talents Project of Universities in Henan(No.22HASTIT010)Special Funds for Fundamental Scientific Research Expenses of Universities in Henan(No.NSFRF210202).
文摘The anchoring eccentricity of the bolt and cable bolt is a common problem in geotechnical support engineering and affects the ability of the bolt and cable bolt to control the rock mass to a certain extent.This paper reports on numerical simulation and laboratory experiments conducted to clarify the effect of eccentricity on the anchoring quality of the bolt and cable bolt,and to establish an effective solution strategy.The results reveal that the anchoring eccentricity causes unbalanced stress distribution and the uncoordinated deformation of the resin layer,which results in higher stress and greater deformation of the resin layer at the near side of the rod body.Additionally,as the degree of anchoring eccentricity increases,the effect becomes more significant,and the resin layer of the anchoring system becomes more likely to undergo preferential failure locally,which weakens the load-bearing performance of the anchoring system.This paper develops an innovative bolt anchoring rectifying device(B-ARD)and cable bolt anchoring rectifying device(C-ARD)on the basis of the structural characteristics of the bolt and cable bolt to better ensure the anchoring effect of them.The working effects of these two devices were verified in detailed experiments and analysis.The experimental results show that the anchoring rectifying devices(ARD)improve and ensure the anchoring concentricity of the bolt and cable bolt,which will help improve the supporting performance of them.The paper provides a convenient and effective method for improving the anchoring concentricity of the bolt and cable bolt,and provides a concept and reference for technical research on improving the effect of roof bolting.
文摘In this paper, the numerical predictions of 3D hydrodynamics and power consumption in a vessel stirred by mul- tiple eccentrically located impellers are presented. The vessel is a fiat-bottomed cylindrical one equipped with six-curved bladed impellers. Aqueous solutions of xanthan gum are used, which have a shear thinning behavior with yield stress. The influence of several parameters on the mixing efficiency has been investigated, namely： the stirring rate, fluid theology, impeller number and impeller clearance from the tank bottom. Our predicted results are compared with other experimental data and a satisfactory agreement is found.
基金Supported in part by Natural Sciences and Engineering Research Council of Canada(NSERC)eMech Systems IncBare Point Water Treatment Plant in Thunder Bay,Ontario,Canada
文摘Induction motors （IMs） are commonly used in various industrial applications. To improve energy con- sumption efficiency, a reliable IM health condition moni- toring system is very useful to detect IM fault at its earliest stage to prevent operation degradation, and malfunction of IMs. An intelligent harmonic synthesis technique is pro- posed in this work to conduct incipient air-gap eccentricity fault detection in IMs. The fault harmonic series are syn- thesized to enhance fault features. Fault related local spectra are processed to derive fault indicators for IM air- gap eccentricity diagnosis. The effectiveness of the pro- posed harmonic synthesis technique is examined experi- mentally by IMs with static air-gap eccentricity and dynamic air-gap eccentricity states under different load conditions. Test results show that the developed harmonic synthesis technique can extract fault features effectively for initial IM air-gap eccentricity fault detection.
基金supported by the National Natural Science Foundation of China(No.50974035)National Natural Science Foundation of China(No.51074047)the doctoral fund of EDU gov(20090407)
文摘In gas injection refining processes, a great amount of gas is injected into molten metal in short time, so that very large bubbles are inevitably formed. Wide dispersion of small bubbles in the bath is indispensable for high refining efficiency. Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion. Absorption rate are used to research on the influence law of the bubble dispersion and disintegration and gas-liquid absorption by the influence of, rotation mode, rotation speed and gas flow rate. Compared to the experimental results of absorption rate under eccentric stirring and centric stirring ,provide the scientific experimental and theoretical guidance for high-temperature experiment of hot metal desulfurization .According to experimental and theoretical analysis, this paper has studied various factors effecting on gas absorption process and volumetric mass transfer coefficient using the system of CO2-NaOH-H2O.The results show that:the volumetric mass transfer coefficient and absorption efficiency of CO2 can be increased under eccentric stirring mode, Because bubble disperse quickly with eccentric mechanical stirring, which results in promoting complete reaction between CO2 and NaOH, and improving the mass transfer coefficient and absorption. Volumetric mass transfer coefficient and efficiency of CO2 increase with the increasing rotation speed under the condition of eccentric stirring .But volumetric mass transfer coefficient and efficiency of CO2 decrease with the increasing rotation speed under the condition of centric stirring.
基金funded by the Research Council of Norway(Grant No.244029)。
文摘The location and geometry of large-scale asperity present at the foundation of concrete gravity dams and buttress dams affect the shear resistance of the concrete-rock interface.However,the parameters describing the frictional resistance of the interface usually do not account for these asperities.This could result in an underestimate of the peak shear stre ngth,which leads to significantly conservative design for new dams or unnecessary stability enhancing measures for existing ones.The aim of this work was to investigate the effect of the location of first-order asperity on the peak shear strength of a concrete-rock interface under eccentric load and the model discrepancy associated with the commonly used rigid body methods for calculating the factor of safety(FS)against sliding.For this,a series of direct and eccentric shear tests under constant normal load(CNL)was carried out on concrete-rock samples.The peak shear strengths measured in the tests were compared in terms of asperity location and with the predicted values from analytical rigid body methods.The results showed that the large-scale asperity under eccentric load significantly affected the peak shear strength.Furthermore,unlike the conventional assumption of sliding or shear failure of an asperity in direct shear,under the effect of eccentric shear load,a tensile failure in the rock or in the concrete could occur,resulting in a lower shear strength compared with that of direct shear tests.These results could have important implications for assessment of the FS against sliding failure in the concrete-rock interface.
