Rotational Behavior Research Articles

Rotational behavior of bolted post-to-beam glulam connections with friction damped knee brace

Alternative bracing systems have been widely applied in heavy timber structures due to its contribution to lateral stiffness and strength, while the improvement in the ductility and energy dissipation capability is limited. Friction damped knee brace is applied in this paper to reinforce rotational behavior of the bolted post-to-beam glulam connections. Monotonic and cyclic loading experiments were conducted on fifteen full-scale specimens. The failure modes, elastic stiffness, moment capacity, hysteresis response and energy dissipation were evaluated and analyzed. The experimental results indicated that with the installation of friction damped knee brace, extremely large initial stiffness was achieved and the moment capacity and accumulated energy dissipation of the post-to-beam connections were increased by 207% and 950%, respectively. Moreover, a multi-segment theoretical model was proposed to predict the rotational behavior of the reinforced bolted glulam connections. The theoretically predicted moment-rotation curves showed good agreement with the experimental results.

Systematic effect of particle roundness/angularity on macro- and microscopic behavior of granular materials

Roundness/angularity is a vital shape descriptor that significantly impacts the mechanical response of granular materials and is closely associated with many geotechnical problems, such as liquefaction, slope stability, and bearing capacity. In this study, a series of biaxial shearing tests are conducted on dual-size aluminum circular and hexagonal rod material. A novel image analysis technique is used to estimate particle kinematics. A discrete element model (DEM) of the biaxial shearing test is then developed and validated by comparing it with the complete experimental data set. To systematically investigate the effect of roundness/angularity on granular behavior, the DEM model is then used to simulate eight non-elongated convex polygonal-shaped particles. Macroscopically, it is observed that angular assemblies exhibit higher shear strengths and volumetric deformations, i.e., dilations. Moreover, a unique relationship is observed between the critical state stress ratio and particle roundness. Microscopically, the roundness shows a considerable effect on rotational behavior such that the absolute mean cumulative rotation at the same strain level increases with roundness. A decrease in roundness results in relatively stronger interlocking, restricting an individual particle’s free rotation. Furthermore, the particles inside the shear band exhibit significantly higher rotations and are always associated with low coordination numbers. Generally, the geometrical shape of a particle is found to have a dominant effect on rotational behavior than coordination number.Graphical

Active Synthetic Microrotors: Design Strategies and Applications.

Microrotors are microscopic objects that convert energy stored in the environment into spontaneous rotation, in the form of spinning along an axis, rolling on a surface, or orbiting in circles. Because of its distinct dynamics and the vertical flows around it, a microrotor is potentially useful for applications, including drug delivery, minimally invasive surgery, fluid mixing, and sensing. It is also useful as a model system to probe the collective behaviors among rotating micro-objects. In this review article, we comprehensively review the recent experimental progress in designing, synthesizing, and using microrotors. For applications, particular emphasis is placed on microfluidic mixing, biomedicine, and collective behaviors. In the end, we comment on how microrotors can be made more biocompatible and more controllable and rotate in more ways and the challenges therein. A key feature of this review article is to introduce three ways in which to classify a microrotor: the nature of its rotational behavior (spinners, rollers, or orbiters), the cause of its rotation (whether chiral symmetry is broken by shapes, chemical compositions, or the way energy is applied), and its power source (whether powered by chemical reactions, electric or magnetic fields, light, or ultrasound). This review article will help materials scientists and chemists in designing micromachines and microrotors, help engineers in finding appropriate microrotors for a specific application, and help physicists in finding appropriate model systems.

528-P: Different Glycemic Responses in People with T1 or T2DM after Use of an Insulin Injection Supporting App

Lipohypertrophy, poor insulin injection technique and missed boluses are well-known issues in the management of diabetes but are sometimes overlooked. This study evaluated whether use of an app with digital training on correct injection routines, site rotation and injection related behaviors will improve glycemic control. Here, we present results of a post hoc analysis on CGM parameters. This was a prospective, open label study with patients on MDI (at least one basal and one bolus insulin injection), HbA1c ≥7% using an intermittent CGM device. A 4-week period without app use was followed by a 4-week period with the use of the app. Time below (<70mg/dl), in (70-180mg/dl), above (>180mg/dl) glycemic ranges, mean glucose, SD & CV were analyzed. 58 patients (37 male, 21 female) completed the study (mean age 52.0 ± 14.6y, diabetes duration 19.2 ± 12.5y, HbA1c 8.0 ± 0.8%, 35 T1DM, 23 T2DM). Overall (N=58), there were significant differences (p<0.001) between baseline and intervention for mean glucose (190.2 (39.2) vs 186.0 (42.0)), time in range (49.9 (17.1) vs 52.6 (18.3)) and time >180 mg/dl (48.2 (17.3) vs 45.4 (18.8)). No significant differences in % of values in hypoglycemia were observed. Table shows mean point estimates for differences from baseline for diabetes subgroups. The use of an insulin injection supporting app leads to improvements in glycemic measures with differences between people with T1DM & T2DM.. Disclosure J.Sieber: Employee; Becton, Dickinson and Company, embecta, Stock/Shareholder; Becton, Dickinson and Company, embecta. I.Wienbarg: None. E.Mahoney: None. T.Haak: None.

Negative Thermal Expansion in the Noncarboxylate Based Metal–Organic Framework Cd(trz)Cl

Negative thermal expansion (NTE), as a counterintuitive phenomenon, has attracted considerable interest owing to its great scientific and technical value. Owing to the inherent structural flexibility, metal–organic frameworks (MOFs) have recently been recognized as an ideal platform for the study of NTE. However, the reported NTE MOFs are mainly restrained in the carboxylate based ones. Herein, we found that the noncarboxylate MOF Cd(trz)Cl (trz = 1,2,4-trizaole) can also exhibit intrinsic volumetric NTE, and a transition from NTE to PTE at high temperatures can be observed. The combined in situ synchrotron powder X-ray diffraction, Raman spectra measurements, and DFT calculations shed light on the fact that the NTE mainly originates from the synergistic effect of geometric flexibility and the enhanced out-of-plane rotation behavior of the trz ligand. This study not only demonstrates a new NTE material but also can help to extend the scope of NTE to the more diverse noncarboxylate based MOFs.

AI-based analysis of 3D position and orientation of red blood cells using a digital in-line holographic microscopy.

The morphological and mechanical characteristics of red blood cells (RBCs) largely vary depending on the occurrence of hematologic disorders. Variations in the rheological properties of RBCs affect the dynamic motions of RBCs, especially their rotational behavior. However, conventional techniques for measuring the orientation of biconcave-shaped RBCs still have some technical limitations, including complicated optical setups, complex post data processing, and low throughput. In this study, we propose a novel image-based technique for measuring 3D position and orientation of normal RBCs using digital in-line holographic microscopy (DIHM) and artificial intelligence (AI). Formaldehyde-fixed RBCs are immobilized in coagulated polydimethylsiloxane (PDMS). Holographic images of RBCs positioned at various out-of-plane angles are acquired by precisely manipulating the PDMS-trapped RBC sample attached to a 4-axis optical stage. With the aid of deep learning algorithms for data augmentation and regression analysis, the out-of-plane angle of RBCs is directly predicted from the captured holographic images. The 3D position and in-plane angle of RBCs are acquired by employing numerical reconstruction and ellipse detection methods. Combining these digital image processing techniques, the 3D positional and orientational information of each RBC recorded in a single holographic image is measured within 23.5 and 3.07s, respectively. The proposed AI-based DIHM technique that can extract the 3D position, orientation, and morphology of individual RBCs would be utilized to analyze the dynamic translational and rotational motions of abnormal RBCs with hematologic disorders in shear flows through further research.

Shell model based description of single-particle and collective excitations in 66Zn

Shell model calculations have been performed in f5/2pg9/2 model space using two different interactions viz., jj44bpn and jun45pn to explore the observed band like structure in 66Zn. Calculated energy values of the excited states are compared with the experimental values and a good agreement is found at low excitation energies. The experimental kinematic moment of inertia and the calculated values using shell model are compared and similar trend is observed. Also, the plotted values of the observed and theoretical alignment suggest very similar gain in the angular momentum of 66Zn. The nature of the variation of calculated energy with spin is very similar to the observation and shows a rotational like behaviour. Observed band crossing phenomenon is also reproduced from the plots of theoretical data points. Thus, these two effective interactions, without any modification, are quite efficient in producing the trend of the observed collectivity in even-even 66Zn nucleus. Configurations and occupation numbers for different states are obtained using the two aforementioned interactions and suggests substantial contribution of 1g9/2 orbital in generating the angular momentum of the high spin states.

In situ observation of crystal rotation in Ni-based superalloy during additive manufacturing process

Understanding the dynamic process of epitaxial microstructure forming in laser additive manufacturing is very important for achieving products with a single crystalline texture. Here, we perform in situ, real-time synchrotron Laue diffraction experiments to capture the microstructural evolution of nickel-based single-crystal superalloys during the rapid laser remelting process. In situ synchrotron radiation Laue diffraction characterises the crystal rotation behaviour and stray grain formation process. With a complementary thermomechanical coupled finite element simulation and molecular dynamics simulation, we identify that the crystal rotation is governed by the localised heating/cooling heterogeneity-induced deformation gradient and recognise that the sub-grain rotation caused by rapid dislocation movement could be the origin of granular stray grains at the bottom of the melt pool.

Effect of Tiaoshen Changzhi acupuncture on behavior and striatum ΔFosB in rats with levodopa-induced dyskinesias

ABSTRACT This study aims to study the effffects of Tiaoshen Changzhi acupuncture on behavior and striatum ΔFosB in rats with Levodopa-induced Dyskinesias (LIDs). In this experimental study, Levodopa-induced Dyskinesia (LID) rat models were established by 6-OHDA double-target injection and randomly assigned to six groups, with ten rats in each group. The rats were subjected to difffferent interventions for 28 days, and their behavior was observed. Additionally, the content of ΔFosB, a marker of neuronal activation, in the rat striatum was detected by immunohistochemistry and qRT-PCR. In contrallateral rotation behavior experiment and AIM experiment, the score of the model group was significantly increased, compared with the model group, the score of the Western medicine group, the ordinary acupuncture group and the Tiaoshen Changzhi group was significantly decreased (P < 0.01), the score of the Western medicine group and the Tiaoshen Changzhi group was significantly lower than the ordinary acupuncture group (P < 0.01), there was no statistical significance between the Western medicine group and the Tiaoshen Changzhi group (P>0.05). In the left forelimb function test, the score of the model group was significantly decreased, and compared with the model group, the left forelimb function score of the Western medicine group, the ordinary acupuncture group and the Tiaoshen Changzhi group were significantly increased (P < 0.01). The left forelimb function score of the Western medicine group and the Tiaoshen Changzhi group was higher than the ordinary acupuncture group (P < 0.05, P < 0.01). There was no statistical significance between Western medicine group and Tiaoshen Changzhi group (P > 0.05). After treatment, the content of ΔFosB in the striatum of the Western medicine group, the ordinary acupuncture group and the Tiaoshen Changzhi acupuncture group all decreased, the Western medicine group was better than the ordinary acupuncture group (P < 0.01), and the Tiaoshen Changzhi acupuncture group was better than the ordinary acupuncture group (P < 0.05). Tiaoshen Changzhi acupuncture can improve the behavioral performance of LID rats, reduce abnormal involuntary movement and contralateral rotation behavior and enhance the motor function of the left forelimb of rats. One of its therapeutic mechanisms for LID may be to reduce the expression level of ΔFosB in the striatum of LID rats, thereby reducing the symptoms of LID rats.

Numerical characterisation of the rotational behaviour of grey cast iron tunnel joints

The structural assessment of segmental grey cast iron (GCI) tunnel linings to nearby construction is challenging due to the presence of the joints affecting the stiffness of the tunnel lining. This paper presents an extensive investigation, using 3D finite element (FE) analyses, into the bending moment-rotation (M-θ) behaviour of two GCI tunnel joint geometries. These two geometries correspond to standard running and station tunnels of the London Underground network. The contribution of this study is two-fold. i) The novel characterisation of the M-θ response enables the development of new models for simulating the mechanical response of GCI tunnel joints with structural elements which can be used in simplified, 2D geotechnical analysis for tunnel safety assessments. ii) The analyses provide insight into the behaviour of GCI tunnel linings that would be difficult to achieve through experimental and field observations alone. More specifically, the analyses show that when the bolts are removed from the joints the possibility of tensile failure can be disregarded; that the initial bolt preload influences the rotational stiffness only after some rotation has taken place and does not alter the bending moment of opening; and that the out-of-plane displacement restraint has little influence on the joint response.

Retraction of "Activated Microglia in the Early Stage of a Rat Model of Parkinson's Disease: Revealed by PET-MRI Imaging by [18F]DPA-714 Targeting TSPO".

In the past decades, translocator protein (TSPO) has been considered as an in vivo biomarker to measure the presence of neuroinflammatory reactions. In this study, expression of TSPO was quantified via [18F]DPA-714 positron emission tomography-magnetic resonance imaging (PET-MRI) imaging to investigate the effects of microglial activation associated with motor behavioral impairments in the 6-hydroxydopamine (6-OHDA)-treated rodent model of Parkinson's disease (PD). [18F]FDG PET-MRI (for non-specific inflammation), [18F]D6-FP-(+)-DTBZ PET-MRI (for damaged dopaminergic neurons), post-PET immunofluorescence, and Pearson's correlation analyses were also performed. The time course of the striatal [18F]DPA-714 binding ratio elevated in 6-OHDA-treated rats during 1-3 weeks post-treatment, with the peak TSPO binding in the 1st week. No differences between bilateral striatum in [18F]FDG PET imaging were found. Moreover, an obvious correlation between [18F]DPA-714 SUVRR/L and rotation numbers was found (r = 0.434, *p = 0.049). No correlation between [18F]FDG SUVRR/L and rotation behavior was found. [18F]DPA-714 appeared to be a potential PET tracer for imaging the microglia-mediated neuroinflammation in the early stage of PD.

Activated Microglia in the Early Stage of a Rat Model of Parkinson's Disease: Revealed by PET-MRI Imaging by [18F]DPA-714 Targeting TSPO.

In the past decades, translocator protein (TSPO) has been considered as an in vivo biomarker to measure the presence of neuroinflammatory reactions. In this study, expression of TSPO was quantified via [18F]DPA-714 positron emission tomography-magnetic resonance imaging (PET-MRI) to investigate the effects of microglial activation associated with motor behavioral impairments in the 6-hydroxydopamine (6-OHDA)-treated rodent model of Parkinson's disease (PD). [18F]FDG PET-MRI (for non-specific inflammation), [18F]D6-FP-(+)-DTBZ PET-MRI (for damaged dopaminergic (DA) neurons), post-PET immunofluorescence, and Pearson's correlation analyses were also performed. The time course of striatal [18F]DPA-714 binding ratio was elevated in 6-OHDA-treated rats during 1-3 weeks post-treatments, with peak TSPO binding in the 1st week. No difference between the bilateral striatum in [18F]FDG PET imaging were found. Moreover, an obvious correlation between [18F]DPA-714 SUVRR/L and rotation numbers was found (r = 0.434, *p = 0.049). No correlation between [18F]FDG SUVRR/L and rotation behavior was found. [18F]DPA-714 appeared to be a potential PET tracer for imaging the microglia-mediated neuroinflammation in the early stage of PD.

Glulam Beam-to-Column Connection with Coupled Steel Rods with Screwheads: Concept and Experimental Verifications

The bolted connections with slotted-in steel plates are basic beam-to-column connections of modern post-and-beam timber building structures. However, due to significantly pinched rotational behaviors, the moment resistance of such connections are usually ignored in design. In this study, the connection-level moment resistance is enabled for modern glulam frame structures with an innovative connection design. A pair of long steel rods with screwheads is designed to generate a force couple at the sides of the connection. The proposed connection could be considered as the key lateral force resisting component, indicating a significant reduction of lateral braces and shear walls. Specimens of the target connection were carefully designed and tested in the lab to obtain their mechanical properties and failure modes. Finite element models were established and calibrated according to the tested data. The moment-rotation curves of the new connection could be easily estimated through a fitted formula. Moreover, the suggestions to improve the proposed connection is also discussed based on the observed damage modes. Results show that the new connection could be treated as rigid moment-resisting connections while the ductility could be further improved.

Theoretical and Experimental Study of Rotational Behaviour of Friction Pendulum Bearings

Friction Pendulum Bearing (FPB for short) is a kind of widely used device to improve seismic capacities of building and bridge structures. Despite the considerable progress made in developing theoretical models to understand the mechanical behaviour of FPB, these models mostly focus on the horizontal movement behaviour and rarely on the rotational behaviour of FPB. However, rotational displacements of FPBs indeed will occur along with horizontal displacements in earthquakes and may affect the structural seismic performance. Motivated from these findings, a theoretical model of FPB that describes the rotational behaviour is established based on the moment balance theory in this paper. A set of rotational tests are carried out to validate the theoretical model, and comparisons of experimental and theoretical results show that they are in good agreement. The theoretical model developed in this paper will help understand the structural seismic performance more accurately in the case of rotations of FPBs.

Does rotation increase the acoustic field of view? Comparative models based on CT data of a live dolphin versus a dead dolphin

Rotational behaviour has been observed when dolphins track or detect targets, however, its role in echolocation is unknown. We used computed tomography data of one live and one recently deceased bottlenose dolphin, together with measurements of the acoustic properties of head tissues, to perform acoustic property reconstruction. The anatomical configuration and acoustic properties of the main forehead structures between the live and deceased dolphins were compared. Finite element analysis (FEA) was applied to simulate the generation and propagation of echolocation clicks, to compute their waveforms and spectra in both near- and far-fields, and to derive echolocation beam patterns. Modelling results from both the live and deceased dolphins were in good agreement with click recordings from other, live, echolocating individuals. FEA was also used to estimate the acoustic scene experienced by a dolphin rotating 180° about its longitudinal axis to detect fish in the far-field at elevation angles of −20° to 20°. The results suggest that the rotational behaviour provides a wider insonification area and a wider receiving area. Thus, it may provide compensation for the dolphin’s relatively narrow biosonar beam, asymmetries in sound reception, and constraints on the pointing direction that are limited by head movement. The results also have implications for examining the accuracy of FEA in acoustic simulations using recently deceased specimens.

Unsteady electrorotation of a viscous drop in a uniform electric field

A dielectric drop suspended in an immiscible dielectric fluid of higher conductivity can spontaneously generate the so-called Quincke rotation (a rotating activity that a weakly conducting drop/solid particle displays in an electric field) subjected to sufficiently strong electric field strength. The steady tilt has been extensively studied and is well elucidated now. However, the unsteady electrorotation of drop remains a largely unclear, complex issue. Motivated by this, we examine the unsteady drop electrorotation in this work with the required integrated convective bulk charge transport effect. First, for the steady rotation, the transient evolution to a steady droplet tilt from the symmetric Taylor state is analyzed in-depth. Here we discover several new phenomena, including the evolving equatorial charge jets. For unsteady rotation, based on a drop's interfacial charge variation, deformation, and tilt angle, the study reports the growth of three distinct rotating patterns in the viscosity ratio range 0.2≤λ=μi/μo≤20.0 and electric field strength E0≤25 kv/cm at a fixed conductivity ratio Q ( = σi/σo) = 0.026 and permittivity ratio S (= ϵi/ϵo) = 0.566. A low-viscosity drop ( λ≤2.5) exhibits only the periodic rotation. For the viscosity ratio 2.5&amp;lt;λ&amp;lt;7.0, the increased electric intensity creates two new unsteady rotation modes: the pseudo-periodic tumbling and the irregular one. For λ≥7, the periodic mode remains absent; instead, the drop displays the electric intensity-dependent tumbling and irregular rotation patterns. Our study shows that the rotation reduces a drop's transitory interfacial charge. At this stage, the drop rotation behavior is controlled by competing charge convection due to fluid flow and charge supply by conduction. The resulting varying electric Reynolds number ReE (the time ratio of charge relaxation and charge convection) explains the created different rotation mechanisms. For ReE&amp;gt;1, owing to lacking enough interfacial charge to sustain rotation, the drop's transition to a temporary non-rotating Taylor state occurs until the interface recharges. The resultant mechanism supports the periodic batch-type rotation for a low-viscosity drop and the irregular rotation for a high-viscosity drop in a higher electric field. In contrast, for ReE&amp;lt;1, the drop timely acquires sufficient charge to support continuous tumbling electrorotation.

Deviation From Rigid Rotational Behavior of Superdeformed Nuclear Bands in Tl and Pb Signature Partners

Deviation From Rigid Rotational Behavior of Superdeformed Nuclear Bands in Tl and Pb Signature Partners

Exploring the potential of artificial intelligence techniques in prediction of the removal efficiency of vortex tube silt ejector

A vortex tube silt ejector is a curative hydraulic structure used to remove sediment deposits from canals and is recognized as one of the most efficient substitutes for physically removing canal sediment. The spatially varied flow in the channel and the rotational flow behavior in the tube make the silt removal process complex. It is even harder to accurately predict the silt removal efficiency by traditional models accurately. However, artificial intelligence (AI) and machine learning approaches have emerged as robust substitutes for studying complex processes. Therefore, this research makes use of AI approaches; support vector machine (SVM), random forest (RF), random tree (RT), and multivariate adaptive regression spline (MARS) to compute the vortex tube silt ejection efficiency using the laboratory data sets. The outcomes of the artificial intelligence (AI)-based techniques also were compared with traditional models. It was found that the RT model (root mean square error, RMSE = 2.165, Nash Sutcliffe efficiency, NSE = 0.98) outperforms the other applied approaches which had relatively more significant result errors. The sensitivity analysis of the process depicts the extraction ratio as the key parameter in the computation of vortex tube silt ejector removal efficiency. The findings of the AI-based approaches discussed in the current study might be helpful for hydraulic engineers as well as researchers in the assessment of the removal efficiency of vortex tube silt ejectors.

A NiCrAlTi coating combining the tough nano-grained matrix and the soft nano-precipitate with outstanding cavitation-resistant performance

To resist the cavitation erosion occurring in the hydrodynamic system, a NiCrAlTi nanocrystalline coating was prepared by the magnetron sputtering and post-annealing treatment. The coating was composed of the tough nano-grained matrix, a large amount of soft B19′-NiTi, a few η-Ni3Ti precipitates, as well as abundant dispersed nano-twins. It showed outstanding cavitation-resistant properties compared to almost all anti-cavitation-erosion materials. Its superior cavitation-resistant property could be attributed to the tough nano-grained matrix and the soft nano-precipitates B19′. The former absorbed the cavitation energy through the high hardness and the enhanced work-hardening ability. The latter rebounded the cavitation energy through the elastic deformation and rotation behaviors.

Seismic performance of stone supported traditional timber frames with or without cap beams

Traditional timber frames in East Asia rest on stone bases, and are uncapped or capped with flat timber beams on their top. This study quantified the influence of the cap beam on the seismic performance of stone supported traditional timber frames. Four column foot and head joints were half-scale fabricated and reversed cyclically tested. Typical damage modes of the joints were identified. Methods were proposed to characterize the joints' rotational behavior. Finite element models of stone supported traditional timber frames with or without cap beams were developed. Lateral performance analysis was conducted on typical full-scale frames based on the developed models; fragility analysis was further performed to evaluate the full-scale frames' seismic performance. The tests indicated that the column foot joints were self-centering and had minor residual parallel to grain deformation. However, the column head joints were found with the embedment deformation at the cap beams, resulting to the pinching of their moment-rotation hysteretic curves. By use of existing hysteretic models in OpenSess whose parameters expressed by the theoretical maximum moment and elastic rotational stiffness, the joints’ rotational behavior was well captured. The numerical study indicated that the cap beam significantly increased the lateral performance and deformability of a frame. The elastic stiffness, lateral load-resisting capacity and cumulative energy dissipation of the frame increased by 77%, 81% and 42%, respectively. Fragility analysis indicated that the cap beam increased more than 33% and 23% of the PGAs corresponding to 50% probability exceedance under life safety drift limit and collapse prevention drift limit, respectively.