Amplitude Of Motion Research Articles

MIDDLE PLEISTOCENE NEOTECTONIC ACTIVATION OF THE MOUNTAIN BORDERING THE MUYA-KUANDA RIFT VALLEY (BAIKAL RIFT ZONE)

Geological and geomorphological studies of the northeastern branch of the Baikal rift zone have revealed structural features of sedimentary strata, as well as the features of lithology and interaction of heterochronous loose sedimentary complexes, block structure of rift valley bottoms and their mountain border, fault network, and activated Cenozoic faults. The Middle Pleistocene neotectonic uplift was identified on the southern slopes of the North Muya and the Kodar ranges and in the mountains bordering the Muya-Kuanda and Parama rift valleys. The authors have studied the parameters of this uplift, determined neotectonic movement amplitudes in the uplift areas, traced the marginal disjunctives and the kinematics of their movements, and identified homochromous sedimentary strata and determined their formation age.The activation of tectonic processes, during which the neotectonic uplift was formed, occurred in the early Middle Pleistocene, before the onset of glaciation. The formation of a dammed lake in the system of Muya-Kuanda rift valleys is associated with the tectonic damming of the Vitim River. During the Middle Pleistocene glaciation, the Kodar Range glaciers have twice formed the ice dams in the area of Lake Oron, which led to the emergence of dammed lakes in the Vitim valley connected with lakes in the Muya-Kuanda troughs. The shoreline of these lakes is preserved as a high rock terrace with an absolute height of 860±10 m along the perimeter of the rift valleys.In the Late Pleistocene, the terrace complex in the Muya-Kuanda rift valleys was mainly formed under the influence of climatic factor.

Deep learning-aided respiratory motion compensation in PET/CT: addressing motion induced resolution loss, attenuation correction artifacts and PET-CT misalignment

PurposeRespiratory motion (RM) significantly impacts image quality in thoracoabdominal PET/CT imaging. This study introduces a unified data-driven respiratory motion correction (uRMC) method, utilizing deep learning neural networks, to solve all the major issues caused by RM, i.e., PET resolution loss, attenuation correction artifacts, and PET-CT misalignment.MethodsIn a retrospective study, 737 patients underwent [18F]FDG PET/CT scans using the uMI Panorama PET/CT scanner. Ninety-nine patients, who also had respiration monitoring device (VSM), formed the validation set. The remaining data of the 638 patients were used to train neural networks used in the uRMC. The uRMC primarily consists of three key components: (1) data-driven respiratory signal extraction, (2) attenuation map generation, and (3) PET-CT alignment. SUV metrics were calculated within 906 lesions for three approaches, i.e., data-driven uRMC (proposed), VSM-based uRMC, and OSEM without motion correction (NMC). RM magnitude of major organs were estimated.ResultsuRMC enhanced diagnostic capabilities by revealing previously undetected lesions, sharpening lesion contours, increasing SUV values, and improving PET-CT alignment. Compared to NMC, uRMC showed increases of 10% and 17% in SUVmax and SUVmean across 906 lesions. Sub-group analysis showed significant SUV increases in small and medium-sized lesions with uRMC. Minor differences were found between VSM-based and data-driven uRMC methods, with the SUVmax was found statistically marginal significant or insignificant between the two methods. The study observed varied motion amplitudes in major organs, typically ranging from 10 to 20 mm.ConclusionA data-driven solution for respiratory motion in PET/CT has been developed, validated and evaluated. To the best of our knowledge, this is the first unified solution that compensates for the motion blur within PET, the attenuation mismatch artifacts caused by PET-CT misalignment, and the misalignment between PET and CT.

On-board synthetic 4D MRI generation from 4D CBCT for radiotherapy of abdominal tumors: A feasibility study.

Magnetic resonance-guided radiotherapy with an MR-guided LINAC represents potential clinical benefits in abdominal treatments due to the superior soft-tissue contrast compared to kV-based images in conventional treatment units. However, due to the high cost associated with this technology, only a few centers have access to it. As an alternative, synthetic 4D MRI generation based on artificial intelligence methods could be implemented. Nevertheless, appropriate MRI texture generation from CT images might be challenging and prone to hallucinations, compromising motion accuracy. To evaluate the feasibility of on-board synthetic motion-resolved 4D MRI generation from prior 4D MRI, on-board 4D cone beam CT (CBCT) images, motion modeling information, and deep learning models using the digital anthropomorphic phantom XCAT. The synthetic 4D MRI corresponds to phases from on-board 4D CBCT. Each synthetic MRI volume in the 4D MRI was generated by warping a reference 3D MRI (MRIref, end of expiration phase from a prior 4D MRI) with a deformation field map (DFM) determined by (I) the eigenvectors from the principal component analysis (PCA) motion-modeling of the prior 4D MRI, and (II) the corresponding eigenvalues predicted by a convolutional neural network (CNN) model using the on-board 4D CBCT images as input. The CNN was trained with 1000 deformations of one reference CT (CTref, same conditions as MRIref) generated by applying 1000 DFMs computed by randomly sampling the original eigenvalues from the prior 4D MRI PCA model. The evaluation metrics for the CNN model were root-mean-square error (RMSE) and mean absolute error (MAE). Finally, different on-board 4D-MRI generation scenarios were assessed by changing the respiratory period, the amplitude of the diaphragm, and the chest wall motion of the 4D CBCT using normalized root-mean-square error (nRMSE) and structural similarity index measure (SSIM) for image-based evaluation, and volume dice coefficient (VDC), volume percent difference (VPD), and center-of-mass shift (COMS) for contour-based evaluation of liver and target volumes. The RMSE and MAE values of the CNN model reported 0.012±0.001 and 0.010±0.001, respectively for the first eigenvalue predictions. SSIM and nRMSE were 0.96±0.06 and 0.22±0.08, respectively. VDC, VPD, and COMS were 0.92±0.06, 3.08±3.73 %, and 2.3±2.1mm, respectively, for the target volume. The more challenging synthetic 4D-MRI generation scenario was for one 4D-CBCT with increased chest wall motion amplitude, reporting SSIM and nRMSE of 0.82 and 0.51, respectively. On-board synthetic 4D-MRI generation based on predicting actual treatment deformation from on-board 4D-CBCT represents a method that can potentially improve the treatment-setup localization in abdominal radiotherapy treatments with a conventional kV-based LINAC.

Structural Quality Factor of Flo-TENG under Stochastic Wave Excitation.

Triboelectric nanogenerators (TENGs) have recently emerged as a promising technology for efficient water wave energy harvesting. However, there is a paucity of clear guidance regarding the optimal designs of TENGs and their shells to achieve efficient absorption and conversion of water wave energy in real random waves. Herein, from the perspective of wave-body interaction and energy transfer, this paper proposes a structural quality factor (Qunit) for the quantitative evaluation of both the motion of floating triboelectric nanogenerator (Flo-TENG) shells and their capability to absorb and convert water wave energy efficiently. The factor is further subdivided into the amplitude structural quality factor (Qacc), which characterizes shell motion amplitude, and the frequency structural quality factor (Qf), which describes shell motion frequency. This paper systematically investigates the impact of various shell parameters such as bow shapes, curvatures, inclinations, and immersion ratios on Qacc and Qf. The findings indicate that variations in shell shape result in distinct Qunit values along different axial directions of wave propagation. These variations directly influence energy absorption efficiency in these directions. These results provide fundamental guidance for the design of high-performance Flo-TENG shells and the selection of internal energy harvesting directions to enable more efficient energy conversion.

Jaw-neck motor function 2 years after whiplash trauma.

There is limited knowledge about the possible long-term effects on jaw motor function after whiplash trauma. The primary aim was to evaluate integrated jaw and head-neck movement amplitudes during jaw function in individuals 2 years after whiplash trauma, compared to controls. The secondary aim was to evaluate changes between the acute stage and a 2-year follow-up in terms of jaw and head-neck movement amplitudes during jaw function. This study included 28 cases exposed to a whiplash trauma 2 years earlier (13 women) and 28 controls (13 women) without previous neck trauma. Head and jaw movement amplitudes were recorded during maximal jaw opening-closing movements using an optoelectronic 3D recording system. For a subpopulation of 12 cases and 15 controls, recordings had also been performed in the acute stage after the whiplash trauma. Jaw and head movement amplitudes were analysed using linear regression with group and sex as independent variables. The subpopulation longitudinal analysis was adjusted for movement amplitudes at baseline. Jaw movement amplitudes were significantly associated with group (coefficient: -0.359: 95% CI: -10.70 to -1.93, p = .006) with smaller amplitudes of jaw movements for whiplash cases. Head movement amplitudes were not associated with group (coefficient: -0.051, 95% CI: -4.81 to 3.20, p = .687). In the longitudinal analysis, both jaw and head movement amplitudes showed significant associations between baseline and the 2-year follow-up. The present findings indicate that the effects on jaw function in terms of jaw opening capacity in the acute stage after whiplash trauma do not spontaneously recover.

Lateralization of acquisition and consolidation in direction but not amplitude of a motor skill task.

Previous research suggests that the neural processes underlying specification of movement direction and amplitude are independently represented in the nervous system. However, our understanding of acquisition and consolidation processes in the direction and distance learning remains limited. We designed a virtual air hockey task, in which the puck direction is determined by the hand direction at impact, while the puck distance is determined by the amplitude of the velocity. In two versions of this task, participants were required to either specify the direction or the distance of the puck, while the alternate variable did not contribute to task success. Separate groups of right-handed participants were recruited for each task. Each participant was randomly assigned to one of two groups with a counter-balanced arm practice sequence (right to left, or left to right). We examined acquisition and, after 24h, we examined two aspects of consolidation: 1) same hand performance to test the durability and 2)the opposite hand to test the effector-independent consolidation (interlimb transfer) of learning. The distance task showed symmetry between hands in the extent of acquisition as well as in both aspects of consolidation. In contrast, the direction task showed asymmetry in both acquisition and consolidation: the dominant right arm showed faster and greater acquisition and greater transfer from the opposite arm training. The asymmetric acquisition and consolidation processes shown in the direction task might be explained by lateralized control and mapping of direction, an interpretation consistent with previous findings on motor adaptation paradigms.

Spatiotemporal correlation enhanced real-time 4D-CBCT imaging using convolutional LSTM networks.

To enhance the accuracy of real-time four-dimensional cone beam CT (4D-CBCT) imaging by incorporating spatiotemporal correlation from the sequential projection image into the single projection-based 4D-CBCT estimation process. We first derived 4D deformation vector fields (DVFs) from patient 4D-CT. Principal component analysis (PCA) was then employed to extract distinctive feature labels for each DVF, focusing on the first three PCA coefficients. To simulate a wide range of respiratory motion, we expanded the motion amplitude and used random sampling to generate approximately 900 sets of PCA labels. These labels were used to produce 900 simulated 4D-DVFs, which in turn deformed the 0% phase 4D-CT to obtain 900 CBCT volumes with continuous motion amplitudes. Following this, the forward projection was performed at one angle to get all of the digital reconstructed radiographs (DRRs). These DRRs and the PCA labels were used as the training data set. To capture the spatiotemporal correlation in the projections, we propose to use the convolutional LSTM (ConvLSTM) network for PCA coefficient estimation. For network testing, when several online CBCT projections (with different motion amplitudes that cover the full respiration range) are acquired and sent into the network, the corresponding 4D-PCA coefficients will be obtained and finally lead to a full online 4D-CBCT prediction. A phantom experiment is first performed with the XCAT phantom; then, a pilot clinical evaluation is further conducted. Results on the XCAT phantom and the patient data show that the proposed approach outperformed other networks in terms of visual inspection and quantitative metrics. For the XCAT phantom experiment, ConvLSTM achieves the highest quantification accuracy with MAPE(Mean Absolute Percentage Error), PSNR (Peak Signal-to-Noise Ratio), and RMSE(Root Mean Squared Error) of 0.0459, 64.6742, and 0.0011, respectively. For the patient pilot clinical experiment, ConvLSTM also achieves the best quantification accuracy with that of 0.0934, 63.7294, and 0.0019, respectively. The quantification evaluation labels that we used are 1) the Mean Absolute Error (MAE), 2) the Normalized Cross Correlation (NCC), 3)the Structural Similarity Index Measurement(SSIM), 4)the Peak Signal-to-Noise Ratio (PSNR), 5)the Root Mean Squared Error(RMSE), and 6) the Absolute Percentage Error (MAPE). The spatiotemporal correlation-based respiration motion modeling supplied a potential solution for accurate real-time 4D-CBCT reconstruction.

Effects of Topology Optimization in Multimaterial 3D Bioprinting of Soft Actuators

Recently, there has been a proliferation of soft robots and actuators that exhibit improved capabilities and adaptability through three-dimensional (3D) bioprinting. Flexibility and shape recovery attributes of stimuli-responsive polymers as the main components in the production of these dynamic structures enable soft manipulations in fragile environments, with potential applications in biomedical and food sectors. Topology optimization (TO), when used in conjunction with 3D bioprinting with optimal design features, offers new capabilities for efficient performance in compliant mechanisms. In this paper, multimaterial TO analysis is used to improve and control the bending performance of a bioprinted soft actuator with electrolytic stimulation. The multimaterial actuator performance is evaluated by the amplitude and rate of bending motion and compared with the single material printed actuator. The results demonstrated the efficacy of multimaterial 3D bioprinting optimization for the rate of actuation and bending.

A forecasting model with hybrid bidirectional long short-term memory for mooring line responses of semi-submersible offshore platforms

Semi-submersible offshore platforms are often produced in the deep sea far away from land, which results in high operating costs and difficult safety maintenance due to the harsh and complex working conditions. Adopting a neural network model for online accurate prediction of mooring tension of semi-submersible offshore platforms can adjust the ballast according to the advance of mooring tension change to keep the platform in a relatively smooth movement amplitude and improve production efficiency. In addition, it can also prevent catastrophic accidents caused by anchor chain breakage due to excessive mooring tension. However, the measured mooring tension of semi-submersible offshore platforms is characterized by complex nonlinear non-stationarity, which leads to insufficient prediction accuracy of a single prediction model. This paper develops a novel online prediction model of mooring tension for semi-submersible offshore platforms based on empirical modal decomposition (EMD), convolutional neural network (CNN), and bidirectional long and short-term memory neural network (BiLSTM). The proposed model is validated using the measured data of the first semi-submersible offshore platform in the South China Sea during operation. The experimental results show that the proposed model outperforms other comparative models currently mainstream for mooring tension prediction. In addition, the proposed method can also be used to predict complex nonlinear data in the field of ship and ocean engineering.

Effects of various freak waves on dynamic responses of a Spar-buoy floating offshore wind turbine

There are various kind of waves in the actual ocean. Changes on freak wave profiles affect the motion of floating offshore wind turbines (FOWTs) and threaten the operation safety. To investigate this issue, the phase modulation method is used to simulate freak waves in our work. The original freak wave is first generated, then the wave profile is modulated to obtain five other types of freak waves, such as the reversed wave, the high-crested wave, the deep-troughed wave, the fluctuated wave, the elevated wave. A coupled time-domain model of a Spar-buoy FOWT is established to simulate the motion under steady wind and various freak waves. The dynamic responses are analyzed in the time domain, including the three-degree-of-freedom (3-DOF) motions of the floating foundation, the tension of mooring line and the nacelle acceleration. The frequency-domain properties under various freak waves are investigated using wavelet analysis. The effects of various wave profiles are compared with the original freak wave. Freak waves in low sea states are also generated to research their effects on pitch motion in different sea states. Results show that the response peaks increase in the impact region under freak waves. The reversed wave increases the maximum value of the 3-DOF motions, especially in pitch motion, and causes the high-frequency energy core of wavelet plots to move. The dynamic responses under the fluctuated wave combines the properties of increased response peaks at high-crested wave and increased amplitude of low-frequency motions at deep-troughed wave. The elevated wave greatly increases the heave motion of the FOWT. The increase in sea state level causes a nonlinear amplification in the transient oscillation.

Aerodynamic effects of an offshore floating photovoltaic platform undergoing pitch and heave motions

The offshore floating photovoltaic (OFPV) platform is a renewable energy generation system that has gained attention in recent years due to several advantages. OFPV exhibits higher sensitivity to wind loads than other offshore platforms, owing to its lightweight design and large aerial coverage. In contrast to the fixed photovoltaic systems, the OFPV platforms experience continuous oscillations induced by waves, which significantly influence the aerodynamic characteristics. In this study, the aerodynamic effects of an oscillating OFPV are investigated using the computational fluid dynamics (CFD) simulation method, including the three-dimensional effects, the Reynolds number effects, and the aerodynamic loads with various kinematic parameters. Some major findings are as follows. Firstly, a large-scale tip vortex exists when OFPV oscillates in pitch and heavy directions, which cannot be detected in two-dimensional simulations. Consequently, the lift coefficient, CL, and the drag coefficient, CD, are highly overestimated in 2-D simulation. Secondly, CL and CD decrease significantly as the Reynolds number increases for cases where Re < 106 while there is only a slight decrease for Re > 106. Thirdly, the aerodynamic forces are highly related to the amplitude of the pitch motion and the phase lag between the pitch and the heave motions. A fitting formula is proposed to calculate CL and CD based on the maximum angle of attack. Lastly, the evolution of the flow fields around the oscillating OFPV is analyzed. The separation of the leading edge mainly causes the aerodynamic force.

Flexural–torsional modal interaction in MEMS actuators initiated by minuscule asymmetry

AbstractAn efficient actuation technique for electrostatic MEMS actuators exploiting electro-mechanical-mechanical modal interactions is proposed. The flexural–torsional equations of motion are established, and we manifest that the initiation of a 2:1 autoparametric modal interaction between in-plane bending and torsional modes of the actuator that is supposed to be symmetrical with respect to its axis of rotation is contingent upon the presence of a quadratic stiffness term, which arises from the existence of non-zero first moments of area of the actual cross-section in prismatic microbeams. In order to efficiently reduce the AC voltage value required to reach the activation of the 2:1 mechanical modal interaction, the electrical resonant frequency is syntonized to half of the natural frequency of the in-plane bending mode. The results indicate that the amplitude of the in-plane motion saturates upon the initiation of an energy exchange between the bending and torsional motions. Through suitable tuning of the AC frequency, the amplitude of the in-plane motion is minimized, while the amplitude of the torsional motion, the indirectly excited mode, is maximized. Our results demonstrate that the actuator's torsional motion, when subjected to a 1:2:1 electro-flexural–torsional modal interactions, is triggered by applying a maximum voltage of 10 V, resulting in about 20 degrees rotational angle. Furthermore, prolific frequency combs are generated as a result of secondary Hopf bifurcations along the large-amplitude response branches, inducing quasi-periodicity in the MEMS dynamics.

Prognostic efficiency of diagnostic blockade as a method of modeling the result of selective neurotomy of the motor branches of the median nerve in patients with cerebral palsy

BACKGROUND: A feature of the disease course in patients with spastic cerebral palsy is a combination of motor neurological disorders with contractures in extremity joints. Neurosurgical methods are currently the main treatment for correcting the pathological tone of the “spastic hand.” However, the decreased tone does not affect secondary (fixed) contractures; therefore, the effectiveness of this type of treatment is extremely dependent on the accurate selection of a certain category of patients. Presumably, diagnostic blockade of the median nerve can create a reversible model for planned neurosurgical treatment. The inclusion of this technique as a standard for examining a patient with spastic cerebral palsy before invasive tone-lowering treatment can radically promote treatment effectiveness. AIM: This study aimed to assess the prognostic effectiveness of diagnostic blockade as a method of modeling the result of selective neurotomy of the motor branches of the median nerve in patients with cerebral palsy. MATERIALS AND METHODS: A longitudinal prospective study enrolled 39 children (aged 5–18 years) with spastic cerebral palsy. Before neurosurgical treatment, each patient underwent a diagnostic n. medianus under electrical stimulation and ultrasound control. After a diagnostic blockade, only patients who had a good functional and goniometric response were selected for the study, which served as an indication for selective neurotomy of the median nerve, and orthopedic treatment was performed in children with a negative event. Patients referred for neurotomy underwent a standardized examination before treatment during the diagnostic blockade and after neurosurgical treatment. The examination included the assessment of the amplitude of passive and active movements in the joints of the upper extremities, muscle tone, and functional capabilities of the upper extremities and dynamometry. RESULTS: In comparison with the initial data, a significant increase in the amplitude of passive and active hand extension, passive and active abduction of the first finger, and upper limb functional capabilities according to the MACS classification and the Miller scale was determined both after the diagnostic blockade and after selective neurotomy of the motor branches of the median nerve. CONCLUSIONS: Based on the results of the study, the effect of the diagnostic blockade and neurosurgical treatment outcomes are unidirectional, which allows the use of blockade as a method for modeling the possible result in clinically complex cases of spastic hand. The use of diagnostic blockade in clinical practice makes it possible to adequately assess the severity of fixed contractures and reduce the pathological hypertonicity of the target muscles. Diagnostic blockade allows for the collection of sufficient information to make an objective decision about which type of treatment is most preferable for each patient – neurosurgical, orthopedic, or sequential use of both methods.

Differential components of bradykinesia in Parkinson's disease revealed by deep brain stimulation.

Bradykinesia is a term describing several manifestations of movement disruption caused by Parkinson's disease (PD), including movement slowing, amplitude reduction, and gradual decrease of speed and amplitude over multiple repetitions of the same movement. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves bradykinesia in patients with PD. We examined the effect of DBS on specific components of bradykinesia when applied at two locations within the STN, using signal processing techniques to identify the time course of amplitude and frequency of repeated hand pronation-supination movements performed by participants with and without PD. Stimulation at either location increased movement amplitude, increased frequency, and decreased variability, though not to the range observed in the control group. Amplitude and frequency showed decrement within trials, which was similar in PD and control groups and did not change with DBS. Decrement across trials, by contrast, differed between PD and control groups, and was reduced by stimulation. We conclude that DBS improves specific aspects of movement that are disrupted by PD, whereas it does not affect short-term decrement that could reflect muscular fatigue.NEW & NOTEWORTHY In this study, we examined different components of bradykinesia in patients with Parkinson's disease (PD). We identified different components through signal processing techniques and their response to deep brain stimulation (DBS). We found that some components of bradykinesia respond to stimulation, whereas others do not. This knowledge advances our understanding of brain mechanisms that control movement speed and amplitude.

Liner orientation change of dual mobility cup determined via 3D ultrasound imaging and motion analysis: A cadaver study

BackgroundA mobile polyethylene liner enables the dual mobility cup (DMC) to contribute to restoring hip joint range-of-motion, decreasing wear and increasing implant stability. However, more data is required on how liner orientation changes with hip joint movement. As a first step towards better understanding liner orientation change in vivo, this cadaver study focuses on quantifying DMC liner orientation change after different hip passive movements, using ultrasound imaging and motion analysis. HypothesisThe liner does not always go back to its initial orientation and its final orientation depends mainly on hip movement amplitude. Methods3D ultrasound imaging and motion analysis were used to define liner and hip movements for four fresh post-mortem human subjects with six implanted DMC. Abduction and anteversion angles of the liner plane relative to the pelvis were measured before and after hip flexion, internal rotation, external rotation, abduction, adduction. ResultsLiner orientation changes were generally defined by angle variation smaller than 5°, with the liner nearly going back to its initial orientation. However, hip flexion caused liner abduction and anteversion angle variations greater than 15°. Except for hip adduction, only weak or no correlation was found between the final angle of the liner and the maximal hip joint movement amplitude. DiscussionThis study is the first attempt to quantify liner orientation change for implanted DMC via ultrasound imaging and constitutes a step forward in the understanding of liner orientation change and its relationship with hip joint movement. The hypothesis that the final liner abduction and anteversion angles depend mainly on hip movement amplitude was not confirmed, even if hip flexion was the movement generating the most liner orientation changes over 15°. This approach should be extended to in vivo clinical investigations, as measured liner angle variation could provide important support for the wear and stability claims made for DMC. Level of evidenceIV; cadaveric study.

Analysis of floating platform-mooring system-pile-soil interactions under wave loadings: A case study of the triangle-shaped semi-submersible platform

The floating platform-mooring system-pile-soil interactions under wave loadings represent a complex yet understudied aspect of floating offshore wind turbines (FOWTs). This paper presents the development and application of an Incompressible Material Point Method-Finite Element Method-Material Point Method (IMPM-FEM-MPM) model to simulate these interactions for a triangle-shaped semi-submersible platform (Tri-SSP), which serves as the foundation of China's first deep-sea FOWT, named ‘Fuyao.’ The proposed model is validated by studying the hydrodynamic responses of the OC4-DeepCwind platform. Under regular waves, increasing wave heights lead to heightened motion amplitudes, with the Tri-SSP exhibiting distinct phase differences between surge, pitch, and heave motions. Anchor Group 1 experiences significant peak tensions, ranging from 2.26 MN to 4.47 MN, which influence soil displacement, shear forces and bending moments along the pile shaft, emphasizing the impact of wave loading on pile-soil interactions. Under 1-h irregular waves, tension in Anchor Group 1 reaches extreme levels, with tensions up to 8 MN observed, underscoring the critical role of mooring systems in mitigating wave-induced forces. The calculated maximum stress within the pile indicates the structural integrity of the DH36 steel pile under these conditions. Comparisons of hydrodynamic responses, both with and without pile-soil interactions, show minimal discrepancies in motion amplitudes, indicating a minor influence on the dynamics of the platform and mooring system. These findings contribute to the understanding of complex interactions in deep-sea FOWTs, informing design and operational strategies for enhanced stability and performance.

Large eddy simulation and linear stability analysis of active sway control for wind turbine array wake

The convective instability of wind turbine wakes allows specific upstream forcing to amplify downstream, leading to increased wake meandering and replenishment, thereby providing a theoretical basis for active wake control. In this study, the active sway control—a strategy previously proven to enhance wake recovery at the single wind turbine level—is analyzed at the turbine array level. The similarity and differences between individual turbine wakes and the wake array are analyzed using large eddy simulations and linear stability analysis, considering both uniform and turbulent inflow conditions. For cases with uniform inflow, large eddy simulations reveal significant meandering motion in the wake array induced by active sway control at a motion amplitude of 1% rotor diameter, consistent with previous studies of standalone wind turbine wakes. Nevertheless, the sensitive frequency for the wake array extends down to St = 0.125 below the limit of St &amp;gt; 0.2 for a single wake, and the optimal control frequency for the standalone turbine wake becomes suboptimal for the array. Linear stability analysis reveals the underlying mechanism of this frequency shift as changes in the shear-layer instability due to the overlap of upstream and downstream wakes and is capable to provide fast estimation of optimal control frequencies. When inflow turbulence intensity increases, the gain of active sway control is reduced, underscoring the importance of low-turbulence environment for successfully implementing the active sway control. The reduction in wake response is captured by the linear stability analysis if the base flow accounts for the faster wake expansion caused by inflow turbulence.

Portable Multi-Layer Capsule-Shaped Triboelectric Generator for Human Motion Energy Harvesting.

This paper introduces a novel portable multi-layer capsule-shaped triboelectric generator (CP-TEG), aimed at optimizing the performance of triboelectric generator technology in terms of miniaturization, modularity, and efficient energy collection. The CP-TEG utilizes a unique multi-layer, stacked structure and an elliptical cylindrical design to increase the effective frictional area and enhance power generation efficiency. Its portable design allows for flexible application in various environments and scenarios. Experimental results demonstrate that the CP-TEG can maintain stable and efficient electrical output under various motion amplitudes and frequencies, and it shows good adaptability to the direction of motion excitation. With a motion amplitude of 7 cm and a frequency of 1.94 Hz, the CP-TEG can charge a 220 μF capacitor to 1.3 V within 100 s. The power generation unit's output voltage and current are more than three times higher than that of traditional single-layer contact-separation mode triboelectric devices. Particularly, its performance in harvesting energy from human motion underscores its effectiveness as a renewable energy solution for wearable devices. Through its innovative structural design and optimized working mechanism, the CP-TEG demonstrates excellent energy collection efficiency and application potential, offering new options for sustainable energy solutions and development.

Nationwide frequency-dependent seismic site amplification models for Iceland

Seismic wave amplification due to localized site conditions or site-effects, is an important aspect of regional seismic hazard assessment. In the absence of systematic studies of frequency-dependent site-effects during strong Icelandic earthquakes, various local site proxies of large-scale studies in other seismic regions have been used and/or proposed for application in Iceland. Recently, however, earthquake site-effects were rigorously quantified for 34 strong-motion stations in Southwest Iceland for the first time and correlated to distinct Icelandic geological units of hard rock, rock, lava rock, and sedimentary soil. These units are prevalent throughout Iceland and in this study therefore, we present 1) nationwide maps of proxies (e.g. slope, Vs30, geological units) that may contribute to a better estimation of site effects and associated, 2) frequency-dependent site-amplification maps of Iceland relative to the median ground-motion prediction of Rahpeyma et al. (2023) [55]. We particularly focus on the two transform zones of the country, on the basis of digital elevation models and detailed geological maps. Specifically, the frequency-dependent site factors for each geological unit are presented at 1, 2, 5, 7, 10–30 Hz, and PGA. Finally, for comparison, we generate site amplification maps based on recent large-scale models developed in other seismic regions and/or applied in other studies (e.g., ESRM20) as well as various site proxies they are based on (e.g., geology- and slope-based inferred VS30, geomorphological sedimentary thickness). We compare site-proxy maps and amplification maps from both Icelandic and large-scale, non-Icelandic, models. Specifically, neither spatial patterns nor amplification levels in either proxy or amplification maps from large-scale non-Icelandic studies resemble those observed from local quantitative strong-motion research as presented in this study. We attribute the discrepancy primarily to the young geology of Iceland and its formation history. Additionally, this study compares model performance across frequencies by assessing the bias of model predictions against empirical site amplifications in the South Iceland Seismic Zone, accounting for site-to-site variability of residuals indicating the superior performance of the local amplification model. The results presented in this study now allow a more informed estimation of earthquake ground motion amplitudes on various geological units that are expected to result in more reliable and information-based seismic hazard estimates in Iceland.

Anatomy and mobility in the adult cadaveric craniocervical junction

AbstractGenetic diseases with craniofacial malformations can be associated with anomalies of the craniocervical joint (CCJ). The functions of the CCJ are thus impaired, as mobility may be either limited by abnormal bone fusion causing headaches, or exaggerated in the case of hypermobility, which may cause irreparable damage to the spinal cord. Restoring the balance between mobility and stability requires surgical correction in children. The anatomy and biomechanics of the CCJ are quite unique, yet have been overlooked in the past decades. Pediatric evidence is so scarce, that investigating the adult CCJ is our best shot to disentangle the form‐function relationships of this anatomical region. The motivation of the present study was to understand the morphological and functional basis of motion in the CCJ, in the hope to find morphological features accessible from medical imaging able to predict mobility. To do so, we have quantified the in‐vitro kinematics of the CCJ in nine cadaveric asymptomatic adults, and estimated a wide range of mobility variables covering the complexity of spinal motion. We compared these variables with the shape of the occipital, the atlas and the axis, obtained using a dense geometric morphometric approach. Morphological joint congruence was also quantified. Our results suggest a strong relationship between bone shape and motion, with the overall geometry predicting best the primary movements, and the joint facets predicting best the secondary movements. We propose a functional hypothesis stating that the musculoligamental system determines movements of great amplitude, while the shape and congruence of joint facets determine the secondary and coupled movements, especially by varying the geometry of bone stops and the way ligaments are tensioned. We believe this work will provide valuable insights in understanding the biomechanics of the CCJ. Furthermore, it should help surgeons treating CCJ anomalies by enabling them to translate objectives of functional and clinical outcome into clear objectives of morphological outcome.