Consistent mechanical and machining properties are essential in many applications where ductile irons offer the most cost-effective way to produce structural parts.In the production of hydraulic rotators,dimensional t...Consistent mechanical and machining properties are essential in many applications where ductile irons offer the most cost-effective way to produce structural parts.In the production of hydraulic rotators,dimensional tolerances are typically 20μm to obtain designated performance.For castings where intermediate strength and ductility is required,it is common knowledge that conventional ferritic-pearlitic ductile irons such as ISO 1083/500-7 show large hardness variations.These are mainly caused by the notoriously varying pearlite content,both at different locations within a part and between parts in the same or different batches.Cooling rate variations due to different wall thickness and position in the molding box,as well as varying amounts of pearlite-stabilizing elements,all contribute to detrimental hardness variations.The obvious remedy is to avoid pearlite formation,and instead obtain the necessary mechanical properties by solution strengthening of the ferritic matrix by increasing silicon content to 3.7wt%-3.8wt%.The Swedish development in this field 1998 resulted in a national standardization as SS 140725,followed in 2004 by ISO 1083/ JS/500-10.Indexator AB decided 2005 to specify JS/500-10 for all new ductile iron parts and to convert all existing parts.Improvements include reduction by 75%in hardness variations and increase by 30%in cutting tool life,combined with consistently better mechanical properties.展开更多
Spiral polarization rotators, rotating polarization ellipse axes clockwise or counterclockwise, depending on the azimuth angle in the transverse plane, are considered. It is shown that spiral polarization rotators lea...Spiral polarization rotators, rotating polarization ellipse axes clockwise or counterclockwise, depending on the azimuth angle in the transverse plane, are considered. It is shown that spiral polarization rotators lead to a change in the order of optical vortices with circular polarization. A comparative analysis of spiral rotators of two types (polar and non-polar) is carried out, using a mirror that allows light to pass in the opposite direction through the rotator. The effect of spiral rotators on optical vortices in a resonator is studied. It is shown that spiral rotators can preserve or accumulate changes of the vortex order during the passage of the beam in both directions. The properties of the spiral rotator and the cube-corner reflector with a special phase-correcting coating, as a diffractive polarization-optical element, are compared.展开更多
The deformation behavior of GH4169 superalloy under room-temperature uniaxial tension was investigated through synchronized mesoscopic digital image correlation(DIC)and electron backscatter diffraction(EBSD)in-situ ch...The deformation behavior of GH4169 superalloy under room-temperature uniaxial tension was investigated through synchronized mesoscopic digital image correlation(DIC)and electron backscatter diffraction(EBSD)in-situ characterization techniques.Results show that in the field of grain deflection dynamics,through quantitative analysis using the independently developed M-DIC software,during uniaxial tension with significant bidirectional rotation along the tensile axis and the stress level of 1100 MPa,oscillatory rotation of±0.6°can be obtained,and microvoids are generated at the grain boundaries with 45°to the stress axis.EBSD crystallographic analysis demonstrates the load-dependent slip system evolution:in the initial stage,the soft-oriented systems with high Schmid factor(>0.4)is activated and then transformed into hard-oriented systems during cross-slip,generating parallel slip bands and dislocation pile-ups at grain boundaries.During the uniaxial tensile process,the characteristic of strain energy accumulation is observed,which follows a two-stage accumulation pattern:initial grain boundary localization(Stage I)and intragranular propagation(Stage II).Ultimately,the intergranular cracks are initiated at triple junctions,and the twin boundaries exhibit superior mechanical stability compared with the large-angle grain boundaries.Deformation texture characteristics indicate the copper-type components,including C{112}<111¯>,S{123}<634¯>,and B{110}<11¯0>.The complete deformation sequence is as follows:cross-slip of soft-oriented slip systems→initiation of dislocation slip→strain partitioning through grain rotation→intergranular stress concentration→damage dominated by boundary cracking.The cross-scale deformation mechanism revealed in this study provides critical guidance for the crystal boundary engineering to optimize nickel-based superalloys.展开更多
We propose a novel cooling protocol within a triple-Laguerre-Gaussian cavity optomechanical system,which is designed to suppress the thermal vibrations of a rotating mirror to reach its quantum ground state.The system...We propose a novel cooling protocol within a triple-Laguerre-Gaussian cavity optomechanical system,which is designed to suppress the thermal vibrations of a rotating mirror to reach its quantum ground state.The system incorporates two auxiliary cavities and an atomic ensemble coupled to a Laguerre-Gaussian rotational cavity.By carefully selecting system parameters,the cooling process of the rotating mirror is significantly enhanced,while the heating process is effectively suppressed,enabling efficient ground-state cooling even in the unresolved sideband regime.Compared to previous works,our scheme reduces the stringent restrictions on auxiliary systems,making it more experimentally feasible under broader parameter conditions.These findings provide a robust approach for achieving ground-state cooling in mechanical resonators.展开更多
We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating sli...We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating slit mechanism,a 3D symmetric spherical focal field distribution is created in the laser-irradiated regions of transparent substrates.The corresponding focal field distribution is theoretically calculated and validated by examining the features of laser-inscribed lines in glass samples.Moreover,we investigate the influences of laser writing speed and slit rotational speed on the fabrication resolution in glass,and discuss the formation mechanism of the generated periodic microstructures.To showcase its powerful capability for3D isotropic fabrication,the high-speed rotating slit beam shaping method is applied to create straight optical waveguides,bending optical waveguides,and hollow microchannels in the glass.The proposed method holds great potential for the facile manufacture of diverse 3D isotropic microstructures and devices within transparent materials across various applications,including advanced photonics,microoptics,micro-electromechanical systems,and microfluidics.展开更多
Irreversible fibrotic scarring after rotator cuff tear(RCT)compromises the mechanical properties of the healing tendon,yet the underlying mechanisms remain poorly understood.Here,we analyzed the histological features ...Irreversible fibrotic scarring after rotator cuff tear(RCT)compromises the mechanical properties of the healing tendon,yet the underlying mechanisms remain poorly understood.Here,we analyzed the histological features of human RCT scars,characterized by disruption of tendon architecture,disorganized collagen fibrils,and imbalance in type Ⅰ/Ⅲ collagen ratios and fibril diameters.Using single-cell RNA sequencing of tendon stumps from patients with RCT,we deconvolved the cellular and molecular landscape of the fibrotic scarring microenvironment.Heterogenous pro-fibrotic subclusters were identified and validated to participate into scar formation,including tendon stem cell,senescent tenocyte,SOX9-driven pro-fibrotic macrophage,and pro-fibrotic endothelial cells undergoing endothelial-mesenchymal transition(EndoMT).Furthermore,we found that osteopontin and TGF-βsignaling were key drivers of extracellular matrix deposition,and their blockade ameliorated fibrotic scarring after RCT.Collectively,our study dissected the dynamic scarring microenvironment in human RCT and highlights potential therapeutic targets for preventing pathological scar formation.展开更多
Objectives:One of the most notable challenges in endoscopic procedures is maintaining correct orientation.Mental rotation exercise(MRE)has been suggested as a potential aid for improving orientation.However,there is a...Objectives:One of the most notable challenges in endoscopic procedures is maintaining correct orientation.Mental rotation exercise(MRE)has been suggested as a potential aid for improving orientation.However,there is a lack of research on designing MREs with varying difficultylevels for training purposes.Furthermore,few studies provide solid evidence linking MRE difficultylevels with cognitive load measurements.This study aims to address this gap by investigating the correlation between the MRE difficultylevels and participants’cognitive load,as measured by pupil dilation.Method:We recruited 33 participants to perform MREs on a computer equipped with a screen-mounted eye-tracker.The test consisted of 15 MREs,with the first10 relatively easy(traditional cube)and the next 5 more complex(invented molecule).The participants’eye movements during MREs were recorded.The participants’MRE scores and pupil dilation were obtained and compared between two MRE difficultylevels.Results:The participants who performed traditional cube MREs achieved significantlybetter MRE scores(0.77±0.11 vs.0.58±0.03,p<0.001)and lower pupil dilation(0.27±0.04 pixels vs.0.47±0.09 pixels,p<0.001)than did those who performed the invented molecule MREs.Moreover,there were significant negative correlations(r=0.62,p=0.015)between pupil dilation and MRE scores.Conclusions:The results revealed a significantnegative correlation between MRE scores and pupil dilation.The more challenging MRE questions led to worse MRE scores but increased pupil dilation.The MRE difficultylevels can be evaluated not only by the degrees or dimensions with which the objects were rotated but also by the participants’MRE scores and pupil dilation.The results of this study provide a basis for training orientation skills in endoscopy using MREs.By incorporating MREs with varying difficultylevels,customized training programs can be developed to enhance camera navigation in endoscopic and laparoscopic procedures.展开更多
As a type of emerging electro-mechanical conversion technology,triboelectric nanogenerators(TENGs)were widely applied in high-entropy energy harvesting,Internet of Things sensing,and biomedical fields due to the chara...As a type of emerging electro-mechanical conversion technology,triboelectric nanogenerators(TENGs)were widely applied in high-entropy energy harvesting,Internet of Things sensing,and biomedical fields due to the characteristics of lightweight,cheap,and high voltage.Among them,the rotating TENG has been extensively researched for its advantages,such as high-precision electrical signals,high electro-mechanical conversion efficiency,and effective output power.In this paper,the working mechanisms of four different rotating TENG modes were introduced in detail.Subsequently,a large amount of research works on the strengthening performance of rotating TENGs were comprehensively introduced and summarized by three gradient classifications.In addition,in view of the many applications of rotating TENGs,they were also systematically divided and generalized into three dimensions.Finally,the problems as well as challenges faced by the current rotating TENG research in the above 16 specific research directions were deeply analyzed,and the possible development directions and the solutions to the above problems were reasonably prospected in the next years.This review hopes to effectively promote the progress of rotating TENG on the road to commercialization.展开更多
In this paper,a theoretical model is established for locally resonant plates with general resonators,and the corresponding governing equation is derived.The model provides a mathematical demonstration of the locally r...In this paper,a theoretical model is established for locally resonant plates with general resonators,and the corresponding governing equation is derived.The model provides a mathematical demonstration of the locally resonant effect,which contains two parts:the first part is induced by translation coupling,and the second part is induced by rotation coupling.The second part cannot be reflected by most existing theoretical models.The analytical solutions of the dynamic response are compared with the direct numerical simulation(DNS)results for two locally resonant plates with different resonator types,thereby validating the general applicability of the present model.The rotation coupling effect leads to the frequency-dependent effective rotational inertia density and anisotropic dispersion relation of the locally resonant plate,as well as the enhancement of the structural vibration suppression ability.展开更多
In this paper,we study the issue of controlling a rotating flexible body-beam system(RFBBS)which consists of a tip mass attached to the free-end and a rigid disk attached to the clamped-end of an Euler-Bernoulli beam....In this paper,we study the issue of controlling a rotating flexible body-beam system(RFBBS)which consists of a tip mass attached to the free-end and a rigid disk attached to the clamped-end of an Euler-Bernoulli beam.The boundary control input is affected by both unknown disturbance and nonlinear input backlash.First,the input backlash is considered as desired control input combined with a nonlinear input error,converting it to an external disturbance,and then,the control signal is designed through the energy-based control method.Next,the closed-loop system’s stability is analysed through Lyapunov direct method.Finally,the efficacy of the proposed control scheme is tested through numerical simulations utilizing the finite difference method.展开更多
BACKGROUND The optimal surgical approach for patients with primary glenohumeral osteoarthritis(GHOA)and an intact rotator cuff remains debated.While anatomic total shoulder arthroplasty(TSA)has traditionally been favo...BACKGROUND The optimal surgical approach for patients with primary glenohumeral osteoarthritis(GHOA)and an intact rotator cuff remains debated.While anatomic total shoulder arthroplasty(TSA)has traditionally been favoured,reverse TSA(RTSA)is increasingly utilized.AIM To systematically compare the outcomes of RTSA and TSA in this specific patient population.METHODS A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines.Retrospective comparative studies evaluating RTSA and TSA in patients with GHOA and intact rotator cuff were included.Key outcomes assessed included complication and reoperation rates,patient-reported outcome measures(PROMs),and range of motion.Risk of bias was assessed using the Risk of Bias in Non-randomized Studies of Interventions tool.RESULTS Twelve studies encompassing 1608 patients(580 RTSA,1028 TSA)met inclusion criteria.RTSA was associated with a lower reoperation rate compared to TSA[odds ratio=0.37;95%confidence interval(CI):0.14-0.94;P value=0.04],while no significant difference in overall complication rates was observed(odds ratio=0.47;95%CI:0.19-1.16;P value=0.10).RTSA patients showed superior outcomes in University of California Los Angeles,Simple Shoulder Test,and Shoulder Pain and Disability Index scores;however,the differences did not exceed the minimal clinically important difference.TSA patients had significantly better external rotation(mean difference=-9.0°;95%CI:-13.21 to-5.02;P value<0.0001).No significant differences were found in other range of motion measures or satisfaction scores.The overall methodological quality of included studies was moderate to serious.CONCLUSION In patients with GHOA and an intact rotator cuff,RTSA may offer comparable or improved outcomes to TSA with lower reoperation rates and similar complication profiles.Functional outcomes favour RTSA in certain patientreported outcome measures,while TSA retains an advantage in external rotation.Surgical decision-making should remain individualized based on patient characteristics and functional demands.展开更多
Objective: To analyze the effectiveness of musculoskeletal ultrasound in diagnosing rotator cuff injuries. Methods: A total of 80 patients with suspected rotator cuff injuries who were admitted and diagnosed between J...Objective: To analyze the effectiveness of musculoskeletal ultrasound in diagnosing rotator cuff injuries. Methods: A total of 80 patients with suspected rotator cuff injuries who were admitted and diagnosed between January 1, 2020, and December 31, 2024, were selected. Musculoskeletal ultrasound was performed on these patients, and the diagnostic efficacy of musculoskeletal ultrasound was evaluated by comparing the results with those of MRI. Results: The detection rates of musculoskeletal ultrasound for the location and extent of injury were similar to those of MRI (p > 0.05). Based on the MRI diagnosis results, the diagnostic accuracy rate of musculoskeletal ultrasound was 92.50%, with a sensitivity of 93.06% and a specificity of 87.50%. The morphological and signal characteristics, as well as ultrasound indicators, of patients with positive musculoskeletal ultrasound results differed significantly from those of patients with negative results (p < 0.05). Conclusion: Musculoskeletal ultrasound can effectively detect the location and extent of rotator cuff injuries, comprehensively assess the damage, and demonstrate high diagnostic efficacy. Furthermore, the morphological and signal characteristics, as well as ultrasound indicators, of musculoskeletal ultrasound can serve as diagnostic criteria for rotator cuff injuries, improving disease detection efficiency.展开更多
[Objectives]To investigate the clinical effects of implementing structured phased rehabilitation training,in addition to conventional rehabilitation,on shoulder joint function and pain alleviation in patients with rot...[Objectives]To investigate the clinical effects of implementing structured phased rehabilitation training,in addition to conventional rehabilitation,on shoulder joint function and pain alleviation in patients with rotator cuff injuries managed conservatively.[Methods]Eighty patients diagnosed with rotator cuff injury were selected and randomly assigned to either the control group or the experimental group,each comprising 40 individuals.The control group received conventional rehabilitation treatment,whereas the experimental group underwent phased rehabilitation training in addition to the conventional treatment for 6 weeks.Assessments were conducted prior to treatment,6 weeks following treatment,and 8 weeks after the completion of treatment(follow-up period).The visual analogue scale(VAS)was employed to evaluate pain intensity,the Constant-Murley score was utilized to assess shoulder joint function,and the shoulder joint range of motion was measured.[Results]Prior to treatment,no statistically significant differences were observed between the two patient groups across all measured indicators(P>0.05).Following 6 weeks of treatment and throughout the follow-up period,both groups exhibited significant reductions in VAS scores compared to baseline measurements,alongside improvements in Constant-Murley scores and shoulder joint range of motion(P<0.05).Furthermore,the magnitude of improvement in the experimental group was significantly greater than that in the control group(P<0.05).[Conclusions]Phased rehabilitation training can enhance shoulder joint function and alleviate pain in patients with rotator cuff injuries beyond the effects of conventional rehabilitation treatment,demonstrating notable clinical application value.展开更多
Rotating Single-Baseline Interferometer(RSBI)systems have attracted considerable attention for Direct Position Determination(DPD)due to their simplicity and high localization accuracy.Nevertheless,the growing complexi...Rotating Single-Baseline Interferometer(RSBI)systems have attracted considerable attention for Direct Position Determination(DPD)due to their simplicity and high localization accuracy.Nevertheless,the growing complexity of electromagnetic environments has led to scenarios with multiple time-frequency aliased sources,rendering conventional DPD methods for RSBI systems ineffective.Previous studies have predominantly concentrated on deploying antenna arrays and applying related signal-processing techniques for localization.Typically,these approaches necessitate that the number of physical antennas exceeds the number of sources.For RSBI systems already in practical operation,this would entail the installation of additional physical antennas,which implies equipment recycling and hardware upgrades.In numerous cases,such modifications are unfeasible.This paper proposes a novel Relative Offset-based Direct Position Determination(RO-DPD)method for RSBI systems that can handle multiple time-frequency aliased sources.The proposed method overcomes the challenge of simultaneous positioning without requiring hardware modifications by leveraging time accumulation and algorithmic enhancements.The implementation of the method involves three key steps.Firstly,the rotation of the interferometer is synthesized into a virtual Uniform Circular Array(UCA).Secondly,a novel estimation variable,termed relative offset,is introduced.The variable serves as an intermediate parameter to establish correlation equations between the positions of multiple time-frequency aliased sources and the intercepted signals.Thirdly,the relative offset model in the UCA is transformed into a virtual Uniform Linear Array(ULA)model,from which the cost function can be derived via the Spatial Smoothing(SS)MUSIC algorithm.Theoretical analysis and simulation results verify the effectiveness of the proposed method.Compared with traditional approaches,the RO-DPD method maintains the low complexity of RSBI systems while demonstrating robust performance in complex electromagnetic environments.展开更多
The accurate segmentation of deep gray matter nuclei is critical for neuropathological research,disease diagnosis and treatment.Existing methods employ the supervised learning training approach,which requires large la...The accurate segmentation of deep gray matter nuclei is critical for neuropathological research,disease diagnosis and treatment.Existing methods employ the supervised learning training approach,which requires large labeled datasets.It is challenging and time-consuming to obtain such datasets for medical image analysis.In addition,these methods based on convolutional neural networks(CNNs)only achieve suboptimal performance due to the locality of convolutional operations.Vision Transformers(ViTs)efficiently model long-range dependencies and thus have the potentiality to outperform these methods in segmentation tasks.To address these issues,we propose a novel hybrid network based on self-supervised pre-training for deep gray matter nuclei segmentation.Specifically,we present a CNN-Transformer hybrid network(CTNet),whose encoder consists of 3D CNN and ViT to learn local spatial-detailed features and global semantic information.A self-supervised learning(SSL)approach that integrates rotation prediction and masked feature reconstruction is proposed to pre-train the CTNet,enabling the model to learn valuable visual representations from unlabeled data.We evaluate the effectiveness of our method on 3T and 7T human brain MRI datasets.The results demonstrate that our CTNet achieves better performance than other comparison models and our pre-training strategy outperforms other advanced self-supervised methods.When the training set has only one sample,our pre-trained CTNet enhances segmentation performance,showing an 8.4%improvement in Dice similarity coefficient(DSC)compared to the randomly initialized CTNet.展开更多
Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoret...Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoretical validation to elucidate the mechanisms of face failure and subsequent ground collapse in saturated ground during slurry pressure-balanced shield(SPBS)tunneling operations.A slurry circulation system was developed to ensure steady shield tunneling and to replicate the phenomena of ground collapse.Investigations into shield tunneling parameters and ground responses,including soil pressure,pore water pressure,and surface subsidence,were conducted to understand the mechanisms of face failure and subsequent ground collapse.The theoretical solution for the critical collapse pressure of the tunnel face,based on the rotational failure mechanism,was validated through the comparison with the experimentally determined critical collapse pressure.The results indicate that:(1)appropriate adjustments of tunneling parameters are crucial for promoting filtercake formation,maintaining chamber pressure,and minimizing ground subsidence;(2)chamber pressure,soil pressure,pore water pressure,and ground subsidence are closely correlated with shield tunneling parameters and the formation of filter cake;(3)ground collapse follows a continuous failure mode due to the destruction of filtercake and the decrease in chamber pressure;(4)the soil pressure at the cutterhead is more sensitive to disturbances from shield tunneling than chamber pressure;and(5)experimentally determined critical collapse pressures is consistent with the theoretical solution of limit analysis.展开更多
Tetrahydrofuran-2,5-dicarboxylic acid(THFDCA)is a bio-based cyclic dicarboxylic acid with greater flexibility and biosafety than the renowned 2,5-furandicarboxylic acid(FDCA),but its synthesis is limited to thermochem...Tetrahydrofuran-2,5-dicarboxylic acid(THFDCA)is a bio-based cyclic dicarboxylic acid with greater flexibility and biosafety than the renowned 2,5-furandicarboxylic acid(FDCA),but its synthesis is limited to thermochemical methods with only several reports.This study pioneers an electrocatalytic strategy for the efficient synthesis of THFDCA via the oxidation of tetrahydrofuran dimethanol(THFDM).By constructing NiCo bimetallic oxides micron sheets on nickel foam(NiCoMS/NF)through controlled pyrolysis of a metal-organic framework(MOF)-like precursor,we achieved a remarkable THFDM conversion of 99.0%and THFDCA yield up to 98.2%,surpassing all reports on thermocatalytic oxidation as we know.In-depth analysis revealed that the synergistic effect between NiO and Co_(3)O_(4) contributes to the high catalytic performance.In-situ Raman and rotating ring-disk electrode(RRDE)techniques were employed to discuss the reaction mechanism and the inhibitory effect on oxygen evolution reaction(OER).This study not only provides a paradigm-shifting,groundbreaking strategy for the synthesis of the flexible cyclic dicarboxylic acid derived from furanic biomass but also offers deep insights into the synergistic effects of electrocatalysts.展开更多
The octupole correlations of the K^(π)=5/2^(+)ground state and the rotational spectrum built on it in^(229)Th are studied using the microscopic relativistic density functional theory on a three-dimensional lattice sp...The octupole correlations of the K^(π)=5/2^(+)ground state and the rotational spectrum built on it in^(229)Th are studied using the microscopic relativistic density functional theory on a three-dimensional lattice space and the reflection-asymmetric triaxial particle rotor model.It is found that^(229)Th has a ground state with static axial octupole and quadrupole deformations.The occurrence of octupole correlations,driven by the octupole deformation,is analyzed through the evolution of single-particle levels around the Fermi surface.The experimental energy spectrum and the electromagnetic transition probabilities,including B(E2)and B(M1),are reasonably well reproduced.展开更多
African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an asses...African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an assessment of soil erosion/deposition models and soil conservation practices,which are supportive for mitigating the impact of soil erosion and maintaining soil health and soil functional services for food security in African drylands.The theories of soil erosion models and soil conservation practices provide advanced ways to understand the detailed impact of soil erosion and management solutions.The paper reviews a set of useful soil erosion models and traditional conservation practices,which can control soil erosion and enhance dryland farming systems in Africa.Soil erosion models are classified into three categories:empirical,conceptual,and physical.Soil conservation practices include reduced tillage,advanced cover crops,mechanical structures(barriers made of stones/gravel/vegetation),advanced mechanical roller-crimper technique,mixed cropping,intercropping,crop rotation systems,terracing techniques,and land modification techniques.These conservation practices are effective in controlling soil erosion,reducing soil damage,improving soil health and quality,enhancing soil fertility,and ensuring food security.The existing assessment suggests that understanding the theories of soil erosion models and soil conservation practices is a first step towards addressing soil erosion problems in African drylands.展开更多
文摘Consistent mechanical and machining properties are essential in many applications where ductile irons offer the most cost-effective way to produce structural parts.In the production of hydraulic rotators,dimensional tolerances are typically 20μm to obtain designated performance.For castings where intermediate strength and ductility is required,it is common knowledge that conventional ferritic-pearlitic ductile irons such as ISO 1083/500-7 show large hardness variations.These are mainly caused by the notoriously varying pearlite content,both at different locations within a part and between parts in the same or different batches.Cooling rate variations due to different wall thickness and position in the molding box,as well as varying amounts of pearlite-stabilizing elements,all contribute to detrimental hardness variations.The obvious remedy is to avoid pearlite formation,and instead obtain the necessary mechanical properties by solution strengthening of the ferritic matrix by increasing silicon content to 3.7wt%-3.8wt%.The Swedish development in this field 1998 resulted in a national standardization as SS 140725,followed in 2004 by ISO 1083/ JS/500-10.Indexator AB decided 2005 to specify JS/500-10 for all new ductile iron parts and to convert all existing parts.Improvements include reduction by 75%in hardness variations and increase by 30%in cutting tool life,combined with consistently better mechanical properties.
文摘Spiral polarization rotators, rotating polarization ellipse axes clockwise or counterclockwise, depending on the azimuth angle in the transverse plane, are considered. It is shown that spiral polarization rotators lead to a change in the order of optical vortices with circular polarization. A comparative analysis of spiral rotators of two types (polar and non-polar) is carried out, using a mirror that allows light to pass in the opposite direction through the rotator. The effect of spiral rotators on optical vortices in a resonator is studied. It is shown that spiral rotators can preserve or accumulate changes of the vortex order during the passage of the beam in both directions. The properties of the spiral rotator and the cube-corner reflector with a special phase-correcting coating, as a diffractive polarization-optical element, are compared.
基金National Natural Science Foundation of China(2022YFF0609300)。
文摘The deformation behavior of GH4169 superalloy under room-temperature uniaxial tension was investigated through synchronized mesoscopic digital image correlation(DIC)and electron backscatter diffraction(EBSD)in-situ characterization techniques.Results show that in the field of grain deflection dynamics,through quantitative analysis using the independently developed M-DIC software,during uniaxial tension with significant bidirectional rotation along the tensile axis and the stress level of 1100 MPa,oscillatory rotation of±0.6°can be obtained,and microvoids are generated at the grain boundaries with 45°to the stress axis.EBSD crystallographic analysis demonstrates the load-dependent slip system evolution:in the initial stage,the soft-oriented systems with high Schmid factor(>0.4)is activated and then transformed into hard-oriented systems during cross-slip,generating parallel slip bands and dislocation pile-ups at grain boundaries.During the uniaxial tensile process,the characteristic of strain energy accumulation is observed,which follows a two-stage accumulation pattern:initial grain boundary localization(Stage I)and intragranular propagation(Stage II).Ultimately,the intergranular cracks are initiated at triple junctions,and the twin boundaries exhibit superior mechanical stability compared with the large-angle grain boundaries.Deformation texture characteristics indicate the copper-type components,including C{112}<111¯>,S{123}<634¯>,and B{110}<11¯0>.The complete deformation sequence is as follows:cross-slip of soft-oriented slip systems→initiation of dislocation slip→strain partitioning through grain rotation→intergranular stress concentration→damage dominated by boundary cracking.The cross-scale deformation mechanism revealed in this study provides critical guidance for the crystal boundary engineering to optimize nickel-based superalloys.
基金Project supported by the National Natural Science Foundation of China(Grant No.62471180)。
文摘We propose a novel cooling protocol within a triple-Laguerre-Gaussian cavity optomechanical system,which is designed to suppress the thermal vibrations of a rotating mirror to reach its quantum ground state.The system incorporates two auxiliary cavities and an atomic ensemble coupled to a Laguerre-Gaussian rotational cavity.By carefully selecting system parameters,the cooling process of the rotating mirror is significantly enhanced,while the heating process is effectively suppressed,enabling efficient ground-state cooling even in the unresolved sideband regime.Compared to previous works,our scheme reduces the stringent restrictions on auxiliary systems,making it more experimentally feasible under broader parameter conditions.These findings provide a robust approach for achieving ground-state cooling in mechanical resonators.
基金supported by the National Key Research and Development Program of China(2022YFA1404800)National Natural Science Foundation of China(12174107,12004221,12192254,92250304,W2441005,12334014,12192251)+4 种基金Natural Science Foundation of Shandong Province(ZR2024QA024,ZR2021ZD02)Postdoctoral Innovation Talents Support Program of Shandong Province(No.SDBX2019005)Shanghai Municipal Science and Technology Major ProjectFundamental Research Funds for the Central UniversitiesEngineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(No.2023nmc005)。
文摘We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating slit mechanism,a 3D symmetric spherical focal field distribution is created in the laser-irradiated regions of transparent substrates.The corresponding focal field distribution is theoretically calculated and validated by examining the features of laser-inscribed lines in glass samples.Moreover,we investigate the influences of laser writing speed and slit rotational speed on the fabrication resolution in glass,and discuss the formation mechanism of the generated periodic microstructures.To showcase its powerful capability for3D isotropic fabrication,the high-speed rotating slit beam shaping method is applied to create straight optical waveguides,bending optical waveguides,and hollow microchannels in the glass.The proposed method holds great potential for the facile manufacture of diverse 3D isotropic microstructures and devices within transparent materials across various applications,including advanced photonics,microoptics,micro-electromechanical systems,and microfluidics.
基金supported by the National Natural Science Foundation of China(NO.82230085,82272572,82030071)National Key Research and Development Program of China(NO.2022YFC2010204)Natural Science Foundation of Hunan Province(NO.2024JJ6637)。
文摘Irreversible fibrotic scarring after rotator cuff tear(RCT)compromises the mechanical properties of the healing tendon,yet the underlying mechanisms remain poorly understood.Here,we analyzed the histological features of human RCT scars,characterized by disruption of tendon architecture,disorganized collagen fibrils,and imbalance in type Ⅰ/Ⅲ collagen ratios and fibril diameters.Using single-cell RNA sequencing of tendon stumps from patients with RCT,we deconvolved the cellular and molecular landscape of the fibrotic scarring microenvironment.Heterogenous pro-fibrotic subclusters were identified and validated to participate into scar formation,including tendon stem cell,senescent tenocyte,SOX9-driven pro-fibrotic macrophage,and pro-fibrotic endothelial cells undergoing endothelial-mesenchymal transition(EndoMT).Furthermore,we found that osteopontin and TGF-βsignaling were key drivers of extracellular matrix deposition,and their blockade ameliorated fibrotic scarring after RCT.Collectively,our study dissected the dynamic scarring microenvironment in human RCT and highlights potential therapeutic targets for preventing pathological scar formation.
文摘Objectives:One of the most notable challenges in endoscopic procedures is maintaining correct orientation.Mental rotation exercise(MRE)has been suggested as a potential aid for improving orientation.However,there is a lack of research on designing MREs with varying difficultylevels for training purposes.Furthermore,few studies provide solid evidence linking MRE difficultylevels with cognitive load measurements.This study aims to address this gap by investigating the correlation between the MRE difficultylevels and participants’cognitive load,as measured by pupil dilation.Method:We recruited 33 participants to perform MREs on a computer equipped with a screen-mounted eye-tracker.The test consisted of 15 MREs,with the first10 relatively easy(traditional cube)and the next 5 more complex(invented molecule).The participants’eye movements during MREs were recorded.The participants’MRE scores and pupil dilation were obtained and compared between two MRE difficultylevels.Results:The participants who performed traditional cube MREs achieved significantlybetter MRE scores(0.77±0.11 vs.0.58±0.03,p<0.001)and lower pupil dilation(0.27±0.04 pixels vs.0.47±0.09 pixels,p<0.001)than did those who performed the invented molecule MREs.Moreover,there were significant negative correlations(r=0.62,p=0.015)between pupil dilation and MRE scores.Conclusions:The results revealed a significantnegative correlation between MRE scores and pupil dilation.The more challenging MRE questions led to worse MRE scores but increased pupil dilation.The MRE difficultylevels can be evaluated not only by the degrees or dimensions with which the objects were rotated but also by the participants’MRE scores and pupil dilation.The results of this study provide a basis for training orientation skills in endoscopy using MREs.By incorporating MREs with varying difficultylevels,customized training programs can be developed to enhance camera navigation in endoscopic and laparoscopic procedures.
基金supported by the China National Postdoctoral Program for Innovative Talents(BX20230037)Talent Fund of Beijing Jiaotong University(2023XKRC034)+1 种基金China Postdoctoral Science Foundation(2023M730205)China Scholarship Council(202407090030)。
文摘As a type of emerging electro-mechanical conversion technology,triboelectric nanogenerators(TENGs)were widely applied in high-entropy energy harvesting,Internet of Things sensing,and biomedical fields due to the characteristics of lightweight,cheap,and high voltage.Among them,the rotating TENG has been extensively researched for its advantages,such as high-precision electrical signals,high electro-mechanical conversion efficiency,and effective output power.In this paper,the working mechanisms of four different rotating TENG modes were introduced in detail.Subsequently,a large amount of research works on the strengthening performance of rotating TENGs were comprehensively introduced and summarized by three gradient classifications.In addition,in view of the many applications of rotating TENGs,they were also systematically divided and generalized into three dimensions.Finally,the problems as well as challenges faced by the current rotating TENG research in the above 16 specific research directions were deeply analyzed,and the possible development directions and the solutions to the above problems were reasonably prospected in the next years.This review hopes to effectively promote the progress of rotating TENG on the road to commercialization.
基金Project supported by the National Natural Science Foundation of China(No.12472062)。
文摘In this paper,a theoretical model is established for locally resonant plates with general resonators,and the corresponding governing equation is derived.The model provides a mathematical demonstration of the locally resonant effect,which contains two parts:the first part is induced by translation coupling,and the second part is induced by rotation coupling.The second part cannot be reflected by most existing theoretical models.The analytical solutions of the dynamic response are compared with the direct numerical simulation(DNS)results for two locally resonant plates with different resonator types,thereby validating the general applicability of the present model.The rotation coupling effect leads to the frequency-dependent effective rotational inertia density and anisotropic dispersion relation of the locally resonant plate,as well as the enhancement of the structural vibration suppression ability.
基金supported in part by the National Natural Science Fundation of China under Grant Nos.62403263 and 62373207in part by the Natural Science Fundation of Qingdao,China under Grant No.24-4-4-zrjj-88-jch+1 种基金in part by the Team Plan for Youth Innovation of Universities in Shandong Province under Grant No.2024KJH148in part by the Foundation of Key Laboratory of Autonomous Systems and Networked Control(South China University of Technology),Ministry of Education under Grant No.2024A01.
文摘In this paper,we study the issue of controlling a rotating flexible body-beam system(RFBBS)which consists of a tip mass attached to the free-end and a rigid disk attached to the clamped-end of an Euler-Bernoulli beam.The boundary control input is affected by both unknown disturbance and nonlinear input backlash.First,the input backlash is considered as desired control input combined with a nonlinear input error,converting it to an external disturbance,and then,the control signal is designed through the energy-based control method.Next,the closed-loop system’s stability is analysed through Lyapunov direct method.Finally,the efficacy of the proposed control scheme is tested through numerical simulations utilizing the finite difference method.
文摘BACKGROUND The optimal surgical approach for patients with primary glenohumeral osteoarthritis(GHOA)and an intact rotator cuff remains debated.While anatomic total shoulder arthroplasty(TSA)has traditionally been favoured,reverse TSA(RTSA)is increasingly utilized.AIM To systematically compare the outcomes of RTSA and TSA in this specific patient population.METHODS A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines.Retrospective comparative studies evaluating RTSA and TSA in patients with GHOA and intact rotator cuff were included.Key outcomes assessed included complication and reoperation rates,patient-reported outcome measures(PROMs),and range of motion.Risk of bias was assessed using the Risk of Bias in Non-randomized Studies of Interventions tool.RESULTS Twelve studies encompassing 1608 patients(580 RTSA,1028 TSA)met inclusion criteria.RTSA was associated with a lower reoperation rate compared to TSA[odds ratio=0.37;95%confidence interval(CI):0.14-0.94;P value=0.04],while no significant difference in overall complication rates was observed(odds ratio=0.47;95%CI:0.19-1.16;P value=0.10).RTSA patients showed superior outcomes in University of California Los Angeles,Simple Shoulder Test,and Shoulder Pain and Disability Index scores;however,the differences did not exceed the minimal clinically important difference.TSA patients had significantly better external rotation(mean difference=-9.0°;95%CI:-13.21 to-5.02;P value<0.0001).No significant differences were found in other range of motion measures or satisfaction scores.The overall methodological quality of included studies was moderate to serious.CONCLUSION In patients with GHOA and an intact rotator cuff,RTSA may offer comparable or improved outcomes to TSA with lower reoperation rates and similar complication profiles.Functional outcomes favour RTSA in certain patientreported outcome measures,while TSA retains an advantage in external rotation.Surgical decision-making should remain individualized based on patient characteristics and functional demands.
文摘Objective: To analyze the effectiveness of musculoskeletal ultrasound in diagnosing rotator cuff injuries. Methods: A total of 80 patients with suspected rotator cuff injuries who were admitted and diagnosed between January 1, 2020, and December 31, 2024, were selected. Musculoskeletal ultrasound was performed on these patients, and the diagnostic efficacy of musculoskeletal ultrasound was evaluated by comparing the results with those of MRI. Results: The detection rates of musculoskeletal ultrasound for the location and extent of injury were similar to those of MRI (p > 0.05). Based on the MRI diagnosis results, the diagnostic accuracy rate of musculoskeletal ultrasound was 92.50%, with a sensitivity of 93.06% and a specificity of 87.50%. The morphological and signal characteristics, as well as ultrasound indicators, of patients with positive musculoskeletal ultrasound results differed significantly from those of patients with negative results (p < 0.05). Conclusion: Musculoskeletal ultrasound can effectively detect the location and extent of rotator cuff injuries, comprehensively assess the damage, and demonstrate high diagnostic efficacy. Furthermore, the morphological and signal characteristics, as well as ultrasound indicators, of musculoskeletal ultrasound can serve as diagnostic criteria for rotator cuff injuries, improving disease detection efficiency.
文摘[Objectives]To investigate the clinical effects of implementing structured phased rehabilitation training,in addition to conventional rehabilitation,on shoulder joint function and pain alleviation in patients with rotator cuff injuries managed conservatively.[Methods]Eighty patients diagnosed with rotator cuff injury were selected and randomly assigned to either the control group or the experimental group,each comprising 40 individuals.The control group received conventional rehabilitation treatment,whereas the experimental group underwent phased rehabilitation training in addition to the conventional treatment for 6 weeks.Assessments were conducted prior to treatment,6 weeks following treatment,and 8 weeks after the completion of treatment(follow-up period).The visual analogue scale(VAS)was employed to evaluate pain intensity,the Constant-Murley score was utilized to assess shoulder joint function,and the shoulder joint range of motion was measured.[Results]Prior to treatment,no statistically significant differences were observed between the two patient groups across all measured indicators(P>0.05).Following 6 weeks of treatment and throughout the follow-up period,both groups exhibited significant reductions in VAS scores compared to baseline measurements,alongside improvements in Constant-Murley scores and shoulder joint range of motion(P<0.05).Furthermore,the magnitude of improvement in the experimental group was significantly greater than that in the control group(P<0.05).[Conclusions]Phased rehabilitation training can enhance shoulder joint function and alleviate pain in patients with rotator cuff injuries beyond the effects of conventional rehabilitation treatment,demonstrating notable clinical application value.
基金partially supported by the National Natural Science Foundation of China(Nos.61901494,62101563)。
文摘Rotating Single-Baseline Interferometer(RSBI)systems have attracted considerable attention for Direct Position Determination(DPD)due to their simplicity and high localization accuracy.Nevertheless,the growing complexity of electromagnetic environments has led to scenarios with multiple time-frequency aliased sources,rendering conventional DPD methods for RSBI systems ineffective.Previous studies have predominantly concentrated on deploying antenna arrays and applying related signal-processing techniques for localization.Typically,these approaches necessitate that the number of physical antennas exceeds the number of sources.For RSBI systems already in practical operation,this would entail the installation of additional physical antennas,which implies equipment recycling and hardware upgrades.In numerous cases,such modifications are unfeasible.This paper proposes a novel Relative Offset-based Direct Position Determination(RO-DPD)method for RSBI systems that can handle multiple time-frequency aliased sources.The proposed method overcomes the challenge of simultaneous positioning without requiring hardware modifications by leveraging time accumulation and algorithmic enhancements.The implementation of the method involves three key steps.Firstly,the rotation of the interferometer is synthesized into a virtual Uniform Circular Array(UCA).Secondly,a novel estimation variable,termed relative offset,is introduced.The variable serves as an intermediate parameter to establish correlation equations between the positions of multiple time-frequency aliased sources and the intercepted signals.Thirdly,the relative offset model in the UCA is transformed into a virtual Uniform Linear Array(ULA)model,from which the cost function can be derived via the Spatial Smoothing(SS)MUSIC algorithm.Theoretical analysis and simulation results verify the effectiveness of the proposed method.Compared with traditional approaches,the RO-DPD method maintains the low complexity of RSBI systems while demonstrating robust performance in complex electromagnetic environments.
基金supported in part by the National Natural Science Foundation of China under Grant 62071405the National Natural Science Foundation of China under Grant 12175189.
文摘The accurate segmentation of deep gray matter nuclei is critical for neuropathological research,disease diagnosis and treatment.Existing methods employ the supervised learning training approach,which requires large labeled datasets.It is challenging and time-consuming to obtain such datasets for medical image analysis.In addition,these methods based on convolutional neural networks(CNNs)only achieve suboptimal performance due to the locality of convolutional operations.Vision Transformers(ViTs)efficiently model long-range dependencies and thus have the potentiality to outperform these methods in segmentation tasks.To address these issues,we propose a novel hybrid network based on self-supervised pre-training for deep gray matter nuclei segmentation.Specifically,we present a CNN-Transformer hybrid network(CTNet),whose encoder consists of 3D CNN and ViT to learn local spatial-detailed features and global semantic information.A self-supervised learning(SSL)approach that integrates rotation prediction and masked feature reconstruction is proposed to pre-train the CTNet,enabling the model to learn valuable visual representations from unlabeled data.We evaluate the effectiveness of our method on 3T and 7T human brain MRI datasets.The results demonstrate that our CTNet achieves better performance than other comparison models and our pre-training strategy outperforms other advanced self-supervised methods.When the training set has only one sample,our pre-trained CTNet enhances segmentation performance,showing an 8.4%improvement in Dice similarity coefficient(DSC)compared to the randomly initialized CTNet.
基金support of the National Natural Science Foundation of China(Grant Nos.52179116 and 51991392)the support of Key Deployment Projects of Chinese Academy of Sciences(Grant No.ZDRW-ZS-2021-3).
文摘Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoretical validation to elucidate the mechanisms of face failure and subsequent ground collapse in saturated ground during slurry pressure-balanced shield(SPBS)tunneling operations.A slurry circulation system was developed to ensure steady shield tunneling and to replicate the phenomena of ground collapse.Investigations into shield tunneling parameters and ground responses,including soil pressure,pore water pressure,and surface subsidence,were conducted to understand the mechanisms of face failure and subsequent ground collapse.The theoretical solution for the critical collapse pressure of the tunnel face,based on the rotational failure mechanism,was validated through the comparison with the experimentally determined critical collapse pressure.The results indicate that:(1)appropriate adjustments of tunneling parameters are crucial for promoting filtercake formation,maintaining chamber pressure,and minimizing ground subsidence;(2)chamber pressure,soil pressure,pore water pressure,and ground subsidence are closely correlated with shield tunneling parameters and the formation of filter cake;(3)ground collapse follows a continuous failure mode due to the destruction of filtercake and the decrease in chamber pressure;(4)the soil pressure at the cutterhead is more sensitive to disturbances from shield tunneling than chamber pressure;and(5)experimentally determined critical collapse pressures is consistent with the theoretical solution of limit analysis.
基金supported by the National Natural Science Foundation of China(22072170,U23A20125)the President Foundation of Ningbo Institute of Materials Technology and Engineering。
文摘Tetrahydrofuran-2,5-dicarboxylic acid(THFDCA)is a bio-based cyclic dicarboxylic acid with greater flexibility and biosafety than the renowned 2,5-furandicarboxylic acid(FDCA),but its synthesis is limited to thermochemical methods with only several reports.This study pioneers an electrocatalytic strategy for the efficient synthesis of THFDCA via the oxidation of tetrahydrofuran dimethanol(THFDM).By constructing NiCo bimetallic oxides micron sheets on nickel foam(NiCoMS/NF)through controlled pyrolysis of a metal-organic framework(MOF)-like precursor,we achieved a remarkable THFDM conversion of 99.0%and THFDCA yield up to 98.2%,surpassing all reports on thermocatalytic oxidation as we know.In-depth analysis revealed that the synergistic effect between NiO and Co_(3)O_(4) contributes to the high catalytic performance.In-situ Raman and rotating ring-disk electrode(RRDE)techniques were employed to discuss the reaction mechanism and the inhibitory effect on oxygen evolution reaction(OER).This study not only provides a paradigm-shifting,groundbreaking strategy for the synthesis of the flexible cyclic dicarboxylic acid derived from furanic biomass but also offers deep insights into the synergistic effects of electrocatalysts.
基金supported by the National Natural Science Foundation of China(Grant Nos.12205097,12141501,12475117,and 12435006)the National Key Laboratory of Neutron Science and Technology(Grant No.NST202401016)+1 种基金the National Key R&D Program of China(Grant Nos.2024YFA1612600 and 2024YFE0109803)the High-performance Computing Platform of Peking University。
文摘The octupole correlations of the K^(π)=5/2^(+)ground state and the rotational spectrum built on it in^(229)Th are studied using the microscopic relativistic density functional theory on a three-dimensional lattice space and the reflection-asymmetric triaxial particle rotor model.It is found that^(229)Th has a ground state with static axial octupole and quadrupole deformations.The occurrence of octupole correlations,driven by the octupole deformation,is analyzed through the evolution of single-particle levels around the Fermi surface.The experimental energy spectrum and the electromagnetic transition probabilities,including B(E2)and B(M1),are reasonably well reproduced.
基金part of the project on soil and water management approved and supported by the Department of Agronomy,Nasarawa State University,Keffi(NSUK),Nigeria。
文摘African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an assessment of soil erosion/deposition models and soil conservation practices,which are supportive for mitigating the impact of soil erosion and maintaining soil health and soil functional services for food security in African drylands.The theories of soil erosion models and soil conservation practices provide advanced ways to understand the detailed impact of soil erosion and management solutions.The paper reviews a set of useful soil erosion models and traditional conservation practices,which can control soil erosion and enhance dryland farming systems in Africa.Soil erosion models are classified into three categories:empirical,conceptual,and physical.Soil conservation practices include reduced tillage,advanced cover crops,mechanical structures(barriers made of stones/gravel/vegetation),advanced mechanical roller-crimper technique,mixed cropping,intercropping,crop rotation systems,terracing techniques,and land modification techniques.These conservation practices are effective in controlling soil erosion,reducing soil damage,improving soil health and quality,enhancing soil fertility,and ensuring food security.The existing assessment suggests that understanding the theories of soil erosion models and soil conservation practices is a first step towards addressing soil erosion problems in African drylands.
