Small Rotation Research Articles

Linear and nonlinear dynamics of self-consistent collisionless tearing modes in toroidal gyrokinetic simulations

We investigate tearing modes (TM) driven by current density gradient in collisionless tokamak plasmas by using the electromagnetic gyrokinetic simulation code ORB5. We elucidate the TM width by simulations for flat profiles, as the absence of background diamagnetic flows implies a small rotation speed, while finite gradients are included to investigate the TM rotation. For flat profiles, the initial saturation width of nonlinearly driven magnetic islands is related to the TM linear growth rate; however, large islands in the initial saturation phase are prone to current density redistribution that reduces the island width in the following evolution. Island-induced E×B and diamagnetic sheared flows develop at the separatrix, able to destabilize the Kelvin–Helmholtz instability (KHI). The KHI turbulence enhances a strong quadrupole vortex flow that reinforces the island decay, resulting in a strong reduction of the island width in an eventual steady state. This process is enhanced by trapped electrons. For finite gradients profile, the TM usually rotates in the electron diamagnetic direction but can change direction when the ion temperature gradient dominates the other gradients. The reduced growth of the TM by diamagnetic effects results in a moderate island size, which remains almost unchanged after the initial saturation. At steady state, strong zonal flows are nonlinearly excited and dominate the island rotation, as expected from previous theoretical and numerical studies. When β is increased, the TM mode is suppressed and a mode with the same helicity but with twisting parity, coupled with the neighboring poloidal harmonics, is destabilized, similar to the kinetic ballooning mode.

Effects of Different Fields of View and Rotation Angles on Radiation Doses to Highly Radiosensitive Organs in Children Using Dental Cone Beam Computed Tomography

Dental cone beam computed tomography (CBCT) is a diverse 3D X-ray imaging technique that has enabled clear visualization of the teeth and surrounding structures. The most common diagnostic purpose of dental CBCT examination in children is ectopic eruption and impacted teeth, and a small field of view (FOV) is often used. Since it is difficult for children to control their body movements, reducing the rotation angle is effective. However, no studies have examined the effects of different rotation angles on radiation doses to highly radiosensitive organs in children using small FOVs. The purpose of this study was to examine the effects of small FOVs (4 × 4 cm and 6 × 6 cm) and rotation angles (360° and 180°) on doses that highly sensitize organs in children using dental CBCT. The entrance surface doses to lenses, thyroid lobes, parotid glands, and sublingual glands of a pediatric whole-body phantom were measured. By reducing the FOV from 6 × 6 cm to 4 × 4 cm, the dose to the sublingual gland could be significantly decreased. Additionally, by reducing the rotation angle from 360° to 180°, the lens dose can be decreased significantly. As the rate of dose reduction varies among organs, it is important to consider the relative positions of different organs with respect to the FOV and the trajectory of the X-ray tube.

A fast search method of buckling load for telescopic boom structure

The telescopic boom structures are extensively utilized in engineering applications involving large mobile cranes, aerial work platforms of significant height, and similar mechanical devices. These are predominantly fabricated using solid-webbed box types, latticed truss designs, or a combination thereof. Under load, they exhibit pronounced geometric nonlinear effects, with the relationship between load and displacement demonstrating marked nonlinear characteristics. This paper focuses on the geometric nonlinear modeling of slender multi flexible beam structures. The overall structural system is divided into several substructures, and the concept of multi flexible system modeling is borrowed to establish a follow-up connected body foundation on each substructure. By decomposing the node displacement and rotation in the substructure, the large displacement and large rotation of the node are decomposed into rigid body motion of the connected base and small displacement and small rotation relative to the connected base, effectively representing the large displacement and large rotation of the substructure as rigid body motion of the connected base. A modeling method for the geometric nonlinear analysis of slender and flexible multibody beam structures is proposed. By decomposing the nodal displacement and rotation within the substructures, the large displacement and rotation of the nodes are broken down into the rigid body motion of the body-fixed coordinate and small displacement and rotation relative to the body-fixed coordinate. This approach establishes the application conditions for calculating the structure’s virtual power of deformation using traditional beam elements with linear strain. A method for solving the instability load of slender and flexible multibody structures is proposed. This method integrates the characteristics of the system’s nonlinear equilibrium equations with respect to load, by deriving the system equations with respect to a load increment control parameter. This paper converts nonlinear equilibrium equations into first-order ordinary differential equation (ODE). The method proposed in this paper provides a more efficient solution for the buckling load of the telescopic boom. It can be used to systematically and quickly calculate the structure of the telescopic boom.

Eulerian rates of elastic incompatibilities applied to size-dependent hardening in finite torsion

Measures of rates of elastic incompatibilities are developed within an Eulerian framework for finite-deformation response of anisotropic elastic-inelastic materials. Such framework relies on the evolution of microstructural vectors. It is emphasized that the rates of incompatibilities, here denoted as Rij, depend on the constitutive equation for the rate of inelasticity. For small strains and rotations, Rij are equal to the negative of the components of the rate of Nye-Kröner’s dislocation density tensor. In contrast to these small strain components, each Rij is invariant under superposed rigid body motions such that it can be used independently in the constitutive equations to describe the material behavior. Specifically, in this work, Rij provide a size-dependent enhancement to hardening that can increase or decrease during loading history, modeling the generation and annihilation of densities of geometrically necessary dislocations in metal plasticity. The application to the finite-deformation torsion of thin wires demonstrates the potential of this approach and the importance of the constitutive equation for the plastic spin rate both on the rotations of the microstructural vectors and on the predicted size-effect.

Role of Brownian motion and Néel relaxations in Mössbauer spectra of magnetic liquids

The absorption cross-section of Mössbauer radiation in magnetic liquids is calculated, taking into consideration both translational and rotational Brownian motion of magnetic nanoparticles as well as stochastic reversals of their magnetization in the absence of an external magnetic field. The role of Brownian motion in ferrofluids is considered in the framework of the diffusion theory, while for the magnetorheological fluids with large nanoparticles, it is done with the aid of Langevin's approach. For stochastic rotation, we derived the equation analogous to Langevin's one and found the corresponding correlation function. In both cases, simple rotational correlation functions are obtained in the approximation of small rotations during the lifetime of the excited Mossbauer nuclei. Influence of the Néel's relaxations is considered in the framework of the Blume - Tjon model.

Modeling and control strategy of small unmanned helicopter rotation based on deep learning

Unmanned Aerial Vehicle (UAV) can serve as a substitute for workers in some hazardous environments, but the presence of ground effects makes UAVs prone to hardware damage during the recycling process. To study the rotation phenomenon of small UAV landing process and propose control strategy, the study completes the rotation modeling of small unmanned helicopter based on deep learning algorithm and proposes the control strategy. The results show that the CNN with ReLU function has the best performance, and the model converges in the 5th iteration with this function, while the model with Sigmoid function converges in the 36th iteration, and the fitting effect of the rotation model constructed by the study is higher than that of the traditional rotation model. The actual trajectory of the research-constructed rotation model starts to coincide with the expected trajectory at the 5th s of the landing process, while the actual trajectory of the Cheeseman-Bennett model starts to coincide with the expected trajectory only at the 26th s of the landing process. Under the control strategy model proposed in the study, the roll angle and pitch angle of UAV are stabilized at 46s, and the fluctuation of yaw angle is also minimal. The rotation model constructed in the study can completely reflect the rotation process of the small UAV, and the designed control system can help the UAV recover stability faster.

Kinematics of rift linkage between the Eastern and Ethiopian rifts in the Turkana Depression, Africa

AbstractRift initiation within cold, thick, strong lithosphere and the evolving linkage to form a contiguous plate boundary remains debated in part owing to the lack of time–space constraints on kinematics of basement‐involved faults. Different rift sectors initiate diachronously and may eventually link to produce a jigsaw spatial pattern, as in the East African rift, and along the Atlantic Ocean margins. The space–time distribution of earthquakes illuminates the geometry and kinematics of fault zones within the crystalline crust, as well as areas with pressurized magma bodies. We use seismicity and Global Navigation System Satellites (GNSS) data from the Turkana Rift Array Investigating Lithospheric Structure (TRAILS) project in East Africa and a new digital compilation of faults and eruptive centres to evaluate models for the kinematic linkage of two initially separate rift sectors: the Main Ethiopian Rift (MER) and the Eastern rift (ER). The ca. 300 km wide zone of linkage includes failed basins and linkage zones; seismicity outlines active structures. Models of GNSS data indicate that the ca. 250 km‐wide zone of seismically active en echelon basins north of the Turkana Depression is a zone, or block, of distributed strain with small counterclockwise rotation that serves to connect the Main Ethiopian and Eastern rifts. Its western boundary is poorly defined owing to data gaps in South Sudan. Strain across the northern and southern boundaries of this block, and an ca. 50 km‐wide kink in the southern Turkana rift is accommodated by en echelon normal faults linked by short strike‐slip faults in crystalline basement, and relay ramps at the surface. Short segments of obliquely oriented basement structures facilitate across‐rift linkage of faults, but basement shear zones and Mesozoic rift faults are not actively straining. This configuration has existed for at least 2–5 My without the development of localized shear zones or transform faults, documenting the importance of distributed deformation in continental rift tectonics.

Investigation of axis-fitting-based measurement and identification techniques for kinematic parameters in multi-joint industrial robots

To improve the positioning accuracy of industrial robots and meet the requirements of industrial applications, this study begins with the structural design of multi-jointed industrial robots and proposes a kinematic calibration method based on axis fitting. The proposed method introduces an axis fitting technique based on circle fitting. Utilizing the results of the axis fitting, a method for establishing link coordinate systems by referencing the Modified Denavit-Hartenberg (MD-H) model is presented. Subsequently, a kinematic parameter identification method is proposed. This study primarily investigates the impact of joint rotation angles on the accuracy of axis fitting. The study reveals that when the rotation angle is greater than or equal to 20°, the circularity of the circle fitting is less than 0.008 mm, and the planarity is less than 0.01 mm, indicating that the proposed fitting algorithm meets the required precision for small angle rotations. Finally, the positioning accuracy of the target robot is verified according to ISO 9283:1998. After calibration, the positioning accuracy at point P1 improves from 1.64 mm to 0.46 mm, an enhancement of 71.95 %, which is the most significant improvement. At point P2, the positioning accuracy improves from 1.75 mm to 0.69 mm, an enhancement of 60.5 %, which is the least improvement. The advantage of this method lies in its ability to identify kinematic parameters that align with the actual structure of the robot using a simple measurement method, thereby improving the robot's positioning accuracy.

Concerted deletions eliminate a neutralizing supersite in SARS-CoV-2 BA.2.87.1 spike

BA.2.87.1 represents a major shift in the BA.2 lineage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is unusual in having two lengthy deletions of polypeptide in the spike (S)protein, one of which removes a beta-strand. Here we investigate its neutralization by a variety of sera from infected and vaccinated individuals and determine its spike (S)ectodomain structure. The BA.2.87.1 receptor binding domain (RBD) is structurally conserved and the RBDs are tightly packed in an "all-down" conformation with a small rotation relative to the trimer axis as compared to the closest previously observed conformation. The N-terminal domain (NTD) maintains a remarkably similar structure overall; however, the rearrangements resulting from the deletions essentially destroy the so-called supersite epitope and eliminate one glycan site, while a mutation creates an additional glycan site, effectively shielding another NTD epitope. BA.2.87.1 is relatively easily neutralized but acquisition of additional mutations in the RBD could increase antibody escape allowing it to become a dominant sub-lineage.

Defect recrystallization in subtransus hot isostatic pressing of electron beam powder bed fusion Ti-6Al-4V

Post-build hot isostatic pressing (HIP) is a widely used method to close as-built defects (gas or lack-of-fusion porosity) in additively manufactured (AM) metal parts. Pore closure during this process often creates clusters of equiaxed grains, in contrast to coarse and directional as-built microstructures widely seen in AM metals. Understanding the mechanisms behind the formation of such microstructures is desirable for controlling anisotropy and improving mechanical properties of AM parts. Prior work has attributed defect-induced equiaxed grains to recrystallization during the HIP process; however the specifics of this recrystallization process have not been explored. This work systematically analyzes the grain structure, orientation, and misorientations of electron beam powder bed fusion (PBF-EB) Ti-6Al-4V to identify the mechanisms by which clusters of equiaxed grains can form during HIP of as-built microstructures. A combination of two mechanisms, dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX), explains the phenomena. Evidence for both these processes is found in small rotations in crystallographic orientation, localized strains around prior pore defects, and specific misorientation distributions. Only subtransus HIP of Ti-6Al-4V was explored in this work. However, the mechanisms presented here are thought to contribute to recrystallization in other HIP processes whether for super-transus Ti-6Al-4V, β-Ti alloys, other alloy systems, or non PBF-EB build processes. These results build upon prior efforts to identify specific mechanisms by which refined microstructures can be achieved in as-HIPed AM metals, improving microstructural control and providing another pathway for microstructural tailoring via AM of metals.

Seismic Response Prediction of Rigid Rocking Structures Using Explainable LightGBM Models

This study emphasizes the explainability of machine learning (ML) models in predicting the seismic response of rigid rocking structures, specifically using the LightGBM algorithm. By employing SHapley Additive exPlanations (SHAP), partial dependence plots (PDP), and accumulated local effects (ALE), a comprehensive feature importance analysis has been performed. This revealed that ground motion parameters, particularly peak ground acceleration (PGA), are critical for predicting small rotations, while structural parameters like slenderness and frequency are more significant for larger rotations. Utilizing an extensive dataset generated from nonlinear time history analyses, the trained LightGBM model demonstrated high accuracy in estimating the maximum rotation angle of rigid blocks under natural ground motions. The study also examined the sensitivity of model performance to lower bound thresholds of the target variable, revealing that reduced feature sets can maintain predictive performance effectively. These findings advance ML-based modeling of seismic rocking responses, providing interpretable and accurate models that enhance our understanding of rocking structures’ dynamic behavior, which is crucial for designing resilient structures and improving seismic risk assessments. Future research will focus on incorporating additional parameters and exploring advanced ML techniques to further refine these models.

Covalent Bond Torsion-Enabled Unique Crystal-Phase Transformation of an Organic Semiconductor for Multicolor Light-Emitting Transistors.

High-mobility and color-tunable highly emissive organic semiconductors (OSCs) are highly promising for various optoelectronic device applications and novel structure-property relationship investigations. However, such OSCs have never been reported because of the great trade-off between mobility, emission color, and emission efficiency. Here, we report a novel strategy of molecular conformation-induced unique crystalline polymorphism to realize the high mobility and color-tunable high emission in a novel OSC, 2,7-di(anthracen-2-yl) naphthalene (2,7-DAN). Interestingly, 2,7-DAN has unique crystalline polymorphism, which has an almost identical packing motif but slightly different molecular conformation enabled by the small bond rotation angle variation between anthracene and naphthalene units. More remarkably, the subtle covalent bond rotation angle change leads to a big change in color emission (from blue to green) but does not significantly modify the mobility and emission efficiency. The carrier mobility of 2,7-DAN crystals can reach up to a reliable 17 cm2 V-1 s-1, which is rare for the reported high-mobility OSCs. Based on the unique phenomenon, high-performance light-emitting transistors with blue to green emission are simultaneously demonstrated in an OSC crystal. These results open a new way for designing emerging multifunctional organic semiconductors toward next-generation advanced molecular (atomic)-scale optoelectronics devices.

The power of feedback in teacher education

PurposeThis qualitative study extends jigsaw lesson study (JLS) by focusing specifically on the impact of feedback on teacher candidates’ (TCs') professional knowledge and instructional growth in the teacher-educator classroom.Design/methodology/approachFor this study, JLS took place in two different methods courses and followed the lesson study (LS) framework using the small group rotations of JLS. In each course, the JLS small group teams taught another team before receiving feedback and revising their lessons. Then they would teach another group. After each iteration, teams debriefed and reviewed the feedback to revise their lessons and prepare for reteaching. Following the JLS process, TCs reflected on the impact of feedback in a post-survey that was analyzed, coded and aligned with their lesson iterations and revisions.FindingsBoth integrated language arts (ILA) and math TCs reported that receiving peer feedback improved their lessons, instructional materials, revisions and student engagement. Through collaboration, TCs valued peer dialog, multiple perspectives and TCs learned to provide and receive constructive feedback professionally. Overall, feedback and collaboration helped strengthen their lesson planning as they considered multiple perspectives. Feedback helped TCs consider differentiation and the diversity of learners as well as student engagement while building their professional knowledge.Originality/valueAlthough a previous study has shown an impact of JLS in ILA teacher-education courses with a broader scope in mathematics courses, this study focused on the JLS process in two teacher-education courses. Furthermore, current research tends to focus on the LS process, but this study focused specifically on TCs’ perceptions of the impact of feedback of their professional and instructional growth.

Small rotations, big impact: A review of rotary files in pediatric dentistry

Small rotations, big impact: A review of rotary files in pediatric dentistry

Pre-operative transverse tendon thickness in small and mid-sized rotator cuff tears does not affect clinical outcomes after arthroscopic repair

IntroductionPrevious studies on rotator cuff tears have examined both clinical and radiographic parameters which may influence post-operative clinical outcomes. While rotator cuff tears are frequently classified by size or depth, there is currently no literature available examining the thickness of the remnant tendon, and its impact on post-operative outcomes. We hypothesize that decreased pre-operative transverse tendon thickness will result in poorer post-operative clinical outcomes. MethodsWe prospectively recruited patients who underwent arthroscopic repair of small to medium full-thickness rotator cuff tears. These patients were followed up for a minimum of 2 years post-operatively. Basic biodata, as well as Visual Analog Scale (VAS) for pain, Constant-Murley Score (CMS), UCLA Shoulder Score (USS), and Oxford Shoulder Score (OSS) at 3 different time points (pre-operatively, 1 year post-operatively, and 2 years post-operatively) were collected. Transverse tendon thickness was measured by independent blinded radiologists on pre-operative ultrasonographic images. Wilcoxon signed-rank test was used to compare outcome scores and multivariable robust linear model was fitted to assess the effect of transverse tendon thickness on post-operative scores. ResultsA total of 63 patients were enrolled in this study, predominantly female (65%) and had a median age of 72 years. Pre-operatively, the median transverse cuff thickness was 5.0 ​mm and median tear size was 1.4 ​cm. The median VAS at preoperative was 7, which reduced to 0 ​at 2 year post-operative, indicating statistically significant improvement in pain levels (p ​< ​0.001). Statistically significant improvement in shoulder function measured by CMS, UCLA score and OSS were also seen over time (p ​< ​0.001). Robust regression analysis revealed that transverse cuff thickness had no statistically significant effect on VAS (p ​= ​0.99), CMS (p ​= ​0.84), UCLA score (p ​= ​0.22), and OSS scores (p ​= ​0.73) at 2 years postoperatively. DiscussionPre-operative transverse tendon thickness of small- to mid-sized supraspinatus tears does not influence clinical outcomes after arthroscopic repair. Differences in transverse tendon thickness may have an association with tendon healing but do not translate to an association with post-operative outcomes in terms of pain, function, and patient-reported outcome measures. Level of evidenceIV.

Simultaneous Thermally Stimulated Delayed Phosphorescence (TSDP) and Thermally Activated Delayed Fluorescence (TADF) in a Two-Coordinated Au(I) Bimetallic Complex Featuring a Tandem Carbene Structure.

A bimetallic, two-coordinated carbene-metal-amine (cMa) Au(I) complex featuring a twisted tandem carbene structure (NHC1-Au-NHC2-Au-carbazolyl) was synthesized. The molecular structure in single crystals revealed a large dihedral angle between the two carbene ligands, while the bridged carbene NHC2 and carbazolyl (Cz) ligands were coplanar. A bluish green thermally stimulated delayed phosphorescence (TSDP) was observed in crystals with an emission lifetime over 70 μs, which can be attributed to the spin allowed diabatic population of a high-lying emissive triplet state from the 3LE characterized low-lying ones. The small rotation energy barrier of Cz along the coordination bond allowed conformers with large dihedral angles between NHC2 and Cz. The ICT characterized S1 state was consequently stabilized to achieve a thermally accessible energy gap to facilitate ISC between triplets and the S1, leading to the thermally activated delayed fluorescence (TADF). Simultaneous TSDP and TADF dual emission can be recorded in its doped polymer film owing to the coexistence of these different conformers.

Effect of repeated pulling loads on Norway spruce (Picea abies (L.) Karst.) trees

Artificial pulling tests are the most practical method of assessing the maximum resistance of trees to lateral forces (e.g., from the wind), particularly in relation to their anchoring capacity in the ground. The traditional method is to pull the tree monotonically until failure. However, there are still many uncertainties regarding the possibility of mimicking wind gusts in such a tree pulling test. More specifically, it is supposed that a succession of wind gusts during a windstorm may cause fatigue to the root system, leading to a propagation of damage at the root-soil interface which will eventually lead to the collapse of the tree. This work aims to provide initial insights into the biomechanical response of shallow-rooted Norway spruce (Picea abies (L.) Karst.) growing in mineral soils by repeatedly pulling to failure six trees with increasing load magnitude. The mechanical behaviour of the tested trees was first analysed using a classical equilibrium approach by calculating peak applied loads, stem base rotation, equivalent stiffness trend over subsequent cycles and residual rotations. Then, the biomechanics of the trees were analysed using an energetic approach, focusing on the energy absorbed and dissipated during either the single load cycle or the complete cyclic test, by applying consolidated procedures used in the field of mechanical engineering.Results show how small but measurable residual rotations were measured after each load repetition, indicating permanent damage even in seemingly undamaged trees. Additionally, loads producing base rotations about 0.3–0.4 times those corresponding to the peak resistance dissipate less than 1 % of the maximum dissipated energy calculated at the same peak point. Additionally, this peak energy is found to be strongly correlated to both the peak moment and a typical stem volume predictor such as diameter at breast height squared times height.All these outcomes are intended to provide a starting point for the development of a different characterisation of tree resistance as an alternative to the current methodologies, especially when it is important to consider the effects of repeated loading on trees.

Quantum Nonlinear Spectroscopy via Correlations of Weak Faraday‐Rotation Measurements

AbstractThe correlations of fluctuations are key to studying fundamental quantum physics and quantum many‐body dynamics. They are also useful information for understanding and combating decoherence in quantum technology. Nonlinear spectroscopy and noise spectroscopy are powerful tools to characterize fluctuations, but they can access only very few among the many types of higher‐order correlations. A systematic quantum sensing approach, called quantum nonlinear spectroscopy (QNS), is recently proposed for extracting arbitrary types and orders of time‐ordered correlations, using sequential weak measurement via a spin quantum sensor. However, the requirement of a central spin as the quantum sensor limits the versatility of the QNS since usually a central spin interacts only with a small number of particles in proximity and the measurement of single spins needs stringent conditions. Here, the aim is to employ the polarization (a pseudo‐spin) of a coherent light beam as a quantum sensor for QNS. After interacting with a target system (such as a transparent magnetic material), the small Faraday rotation of the linearly polarized light can be measured, which constitutes a weak measurement of the magnetization in the target system. Using a Mach–Zehnder interferometer with a designed phase shift, one can post‐select the effects of the light–material interaction to be either a quantum evolution or a quantum measurement of the material magnetization. This way, the correlated difference photon counts of a certain number of measurement shots, each with a designated interference phase, can be made proportional to a certain type and order of correlations of the magnetic fluctuations in the material. The analysis of the signal‐to‐noise ratios shows that the second‐order correlations are detectable in general under realistic conditions and higher‐order correlations are significant when the correlation lengths of the fluctuations are comparable to the laser spot size (such as in systems near the critical points). Since the photon sensor can interact simultaneously with many particles and interferometry is a standard technique, this protocol of QNS is advantageous for studying quantum many‐body systems.

Outcome of arthroscopic suturing repair of nonretracted full-thickness rotator cuff tears with fast-track rehabilitation

Background: This study aims to evaluate the effectiveness of nonretracted full-thickness rotator cuff tears with arthroscopic rotator cuff suturing, and examine whether clinical functional outcomes are superior in the fast-track rehabilitation team. Objectives: To study the effects of arthroscopic rotator cuff suturing in the treatment of nonretracted full-thickness rotator cuff tears. Methods: From August 2013 to May 2018, 68 cases of nonretracted full-thickness rotator cuff tears underwent arthroscopic rotator cuff suturing repair. Postoperatively, 35 arms were suspended with a triangular arm sling, without immobilization at abduction or the 0-degree position. The remaining 33 arms were traditionally immobilized after operation for 6 weeks. All patients were evaluated using the University of California Los Angeles (UCLA) Shoulder Rating Scale (UCLA score), Constant-Murley score and VAS pain score before the operation and during the follow-up visits. Results: The follow-up time ranged from 12 to 36 months with an average of 12.1 months. All patients were satisfied with their operations. There were no significant differences in preoperative UCLA score, Constant-Murley score and VAS pain scores between the groups. Both groups showed significant improvement in these clinical function scores at follow-up. There were no significant differences in the UCLA score, Constant-Murley score, and VAS pain scores between the 2 groups at the last follow-up. However, the fast-track team had better activity motion especially in flexion and external rotation movement, suggesting that the triangular arm sling is as effective as the traditional immobilization in postoperative rehabilitation and allow patients to better perform rehabilitation exercises. Conclusions: Arthroscopic suturing repair is a safe, efficient and minimally invasive treatment for nonretracted full-thickness rotator cuff tears. For small nonretracted rotator cuff tears, compared with the traditional team, the fast-track rehabilitation team achieved faster recovery and higher patient’s satisfaction.

Numerical simulation study of hydraulic performance of the ball valve implied in ultra-high head Pelton turbine

Abstract This paper is deal with the hydraulic performance of the ball valve served in ultra-high head Pelton turbine systems, the Moving Particle Simulation method is used for numerical simulation uncommonly instead of the Finite Volume method. A valve rotating range of 0 degree to 90 degree is simulated by the software Particleworks, according to the pressure change through the valve, we get the flow resistance coefficient which is consistent with those of other similar literature. The change of the internal flow distribution can be visually observed. At the small rotation degree, the flow velocity entering the ball valve is very high and the disturbance in flow field is large. With the rotation degree increases, the flow in ball valve and the outlet pipe is gradually stabilized, the pressure difference before and after the ball valve is gradually reduced. It brings reference value for the structure and size design of the ball valve in the future.