Vertical Axis Research Articles

A Top Model of Urban Residents’ Subjective Well-Being in China

Past research on subjective well-being (SWB) in Western society and China has revealed various contributing factors. This study conducted a series of interviews with Chinese urban residents to systematically analyze those factors based on Bronfenbrenner’s Ecological System Theory. The results revealed that 5 layers, 23 factors, and 55 elements, many of which had distinct Chinese characteristics, contributed to Chinese urban residents’ SWB. The Top Model of SWB, visualized as a spinning top or gyroscope, showcased the interdependent layers of factors impacting Chinese urban residents’ SWB. At its vertical axis is a time dimension as residents often reflect on factors by comparing their present situation with the past and the future. Discussion regarding each layer, the primary factors that comprise each layer, links between the layers, and the impact of a time dimension was included to substantiate the proposed model. The discussions focus on the study’s contribution to SWB literature, public policy-making, and future research on urban Chinese residents’ SWB.

Design and kinematics analysis of a cable-stayed notch manipulator for transluminal endoscopic surgery

The friction between the joints of the continuum manipulator with discrete joints brings great difficulties to kinematic modeling. The traditional driving wire arrangement limits the load capacity of the manipulator. A cable-stayed notch manipulator for transluminal endoscopic surgery is proposed, and a driving force coupling kinematic mode is established. The manipulator is fabricated from a superelastic Nitinol tube with bilaterally cut rectangular notches and is actuated by a stay cable. By applying the comprehensive elliptic integral solution (CEIS) for large deformation beams, the bending angle of each elastic beam is obtained, and the kinematics from the driving space to the joint space is formed. According to the bending angle of each elastic beam, the expression of the manipulator in Cartesian space can be obtained by geometric analysis. The kinematics from the joint space to the Cartesian space is established. The outer diameter of the manipulator is only 3.5 mm, and the inner diameter can reach 2 mm, allowing instruments to pass through. The maximum error of the manipulator movement is less than 5%. The load capacity of the manipulator has been verified through the stiffness experiments, and the maximum load of the manipulator can reach 400 g. The cable-stayed notch manipulator can be accurately modeled on the base of CEIS, and its motion accuracy can meet the needs of engineering applications. The compact size and excellent load capacity of the manipulator make it potential for application in transluminal endoscopic surgical robots.

Impact of scapula anatomical landmark positioning on scapular orientation using CT-based 3D models: an intra-observer repeatability and inter-observer reproducibility study

HypothesisThe primary objective of this study was to assess intra-observer repeatability and inter-observer reproducibility of the 3D coordinates of a set of scapula anatomical landmarks obtained by manual positioning on conventional supine CT-scan based scapula surface models. The secondary objective was to assess intra-observer repeatability and inter-observer reproducibility of the resulting 3D scapular orientation. It was hypothesized that the 3D scapular orientation reliability would be better or similar than established reliability of intra-operative baseplate positioning (i.e. version and inclination) in reverse total shoulder arthroplasty (rTSA). MethodsThree anatomical landmarks, i.e. acromial angle (AA), inferior angle (IA), and trigonum scapulae (TS), were manually positioned on 81 scapula surface models using updated landmark definitions. These models were obtained by the segmentation of CT-scan images acquired from patients undergoing elective rTSA procedures at the Department of Surgery at Geneva University Hospitals between May 2022 and December 2023. This procedure was repeated 3 times per scapula by 3 independent observers. A set of parameters corresponding to the 3D landmark coordinates (expressed in an average scapula coordinate system) and the 3D scapular orientation (expressed as three angles related to the retraction/protraction, lateral/medial rotation, and internal/external rotation) were computed. Intra-observer repeatability and inter-observer reproducibility were assessed for each of these parameters using an intra-class correlation as a relative reliability metric. Standard error of measurement (SEM) was also reported as an absolute reliability metric. ResultsIntra-observer ICC and inter-observer ICC ranged from poor to moderate for AA, poor to excellent for IA, and poor to excellent for TS. However, low SEM, ranging from 0.4 mm to 2.4 mm for intra-observer repeatability and from 0.2 mm to 1.8 mm for inter-observer reproducibility, were obtained for every coordinate of each anatomical landmark. This results in poor to moderate intra-observer ICC and inter-observer ICC for scapula angular orientation. Again, low SEM, ranging from 0.4° to 0.8° for intra-observer repeatability and 0.4° to 0.6° for inter-observer reproducibility, were obtained, arguing for reliable measurements. Discussion and ConclusionThis study demonstrates that manual positioning of the three scapula anatomical landmarks recommended by the International Society of Biomechanics can be performed in a reliable manner across measures and observers on surface bone models obtained from CT-scan images. However, a clear and standardized definition of these landmarks is needed to ensure consistency across measurements.

Analytical and geometric interpretation of the flat arrangement of points by means of metric geometry in the study of metric spaces

Abstract When studying metric spaces, students of higher education often have difficulties with understanding the basic concepts and properties of these spaces. This, to a large extent, is a consequence of the significant level of formalization of such concepts on the one hand, and the preservation of the corresponding formulations and names familiar to students from a school mathematics course. To overcome these difficulties, it is advisable to use methods of geometric interpretation and visualization of these properties. At the same time, it is appropriate to use elements of metric geometry. Its methods make it possible to interpret the geometric features of the mutual placement of points of metric space in Cartesian (rectangular) coordinate systems, which are familiar to students of higher education. Moreover, it becomes possible to visualize these features with the help of graphic editors, since they, as a rule, use numerical values of the coordinates of points to visualize them. Based on the definition of an angle as an ordered trio of points of an arbitrary metric space, and the angular characteristic of this angle, the fact of the flat placement of four points of a non-Euclidean metric space is established, and examples of digital visualization of this arrangement using the dynamic geometric environment GeoGebra 3D are given.

Delayed Maxillary Reconstruction with Free Osteocutaneous Fibula Flap Using CAD-CAM Technology

Abstract Background Maxillary reconstruction poses unique challenges for the reconstructive surgeon because of the complex three-dimensional (3D) anatomy of the maxilla. Undertaking this endeavor on secondary reconstruction makes it more difficult due to problems in recreating the true defect. This study is an attempt to demonstrate the role of virtual surgical planning (VSP), 3D printing, and mock surgery in reconstructing such defects using free fibula flaps. Materials and Methods This was a prospective study involving 10 patients of maxillary defects who underwent delayed reconstruction with a free fibula flap. The planning was done preoperatively using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. A mock surgery with 3D printed models was done before the surgery. After the surgery, the accuracy results were obtained by overlapping and measuring fixed point distances between preoperative virtual planning and postoperative computed tomography (CT) scan data. Results and Discussion Nine patients underwent successful reconstruction and were satisfied with the outcome. One patient had flap loss. The mean shift along the horizontal, vertical, and 3D axes was less than 5 mm between the preoperative virtual planning and postoperative CT scan data, indicating accurate reconstruction. We also suggest strategies for soft-tissue and bony inset including inferolateral pedicle origin, anteriorly facing lateral fibular surface, and two bony struts for the alveolus. Conclusion VSP and CAD-CAM technology in maxillary reconstructions help achieve an anatomically accurate neo-maxilla. The addition of mock surgery to the routine and the use of cutting guide avoid unpredictability and reduce the need for adaptation activities on the operating table. CAD-CAM technology despite its limitations is invaluable in maxillary reconstruction and is an important tool for a reconstructive plastic surgeon.

Moshinsky Brackets for a Wide Range of Quantum Numbers Using Generating Functions

We used a new Python code to reproduce the brackets for the Moshinsky harmonic oscillator, which was based on the generating function. We made these brackets by transforming the wave functions of two groups of coupled particle harmonic oscillators, Φn1l1,n2l2,Λm1,m2,λ(r→1,r→2) and Φnala,nblb,Λma,mb,λ(r→a,r→b). To convert between the supplied position and momentum coordinates in both frames, We performed orthogonal transformations on nuclei with both low and high angular momentum.In our derivation, we have used the expansion of the generating functions e2p→.r→−p2 and e2cpi.pj in spherical coordinates in terms of harmonic oscillator wave functions. When we modified the Moshinsky brackets for two-coupled oscillator states, we used generating functions with two variables. The number of indices has significantly decreased compared to the oscillator brackets in previous references; this reduction in the program code's iterative process has yielded influential results. Compared to the previous version of the Moshinsky brackets code, the new Python code is easier to use. Our approach utilizes this code to assess Moshinsky brackets across a broad spectrum of quantum numbers. According to the revelation, adding more variables to the generating function makes the number of Moshinsky brackets that work for the higher body interactions increase.

Exploring the Potential Relationship between Cooling Green Space and Built-up area: Analysis of Community Green Space Characteristics Based on GWPCA

Rapid urbanization exacerbates urban heat island (UHI) problem. Although urban green space (UGS) can produce multiple benefits for mitigating UHI, the accompanying problems of urban development cause multiple pressures on greenery. Therefore, the pattern of green spaces should be adjusted to adapt to the current situation of the built-up area, fully utilizing its cooling effect, which is of great significance for achieving sustainable and balanced urban development. We selected 849 community units in Harbin city for the study, calculated the urban green space pattern index (UGSP) based on geographically weighted principal component analysis (GWPCA), And used bivariate choropleth map and Cartesian coordinate system to explore the spatial relationship between UGSP and associated characteristics of urbanization (e.g., land function diversity and development intensity). The results showed the following. (1) Compared with traditional PCA, GWPCA can capture local details of UGSP, especially proportion of tree area was the most sensitive factor in the urban core area, and FRAC_MN and LSI were the sensitive factors in the west and south of urban outer areas, respectively. (2) The matching degree between development intensity (I) and UGSP was slightly better than that between land function diversity (D) and UGSP, and showed a more egalitarian phenomenon. (3) The equilibrium value (dLow) presented a relatively random spatial distribution when UGSP was less than D/I, and the unbalanced value (dHigh) was scattered in the core area. Both dLow and dHigh were concentrated outside the urban core area when UGSP was greater than D/I. Our study provides an effective guidance for community greenery to mitigate UHI and realize the harmonious coexistence between city and nature.

2D mechanical representation of superconducting magnets: A comparative study of plane stress and plane strain

When approaching the mechanical design of a superconducting magnet, whenever possible the starting model is a 2D approximation. If rotational symmetry (solenoid-like winding) is present, the 2D representation is unique and contains no approximations. If, on the other hand, a non-axisymmetric system is opted for, the 2D representation is not unique and there are main options available, as plane stress, plane stress with thickness, plane strain and generalized plane strain. Considering z as the direction normal to the 2D plane, the plane stress option defines a stress state in which no normal or shear stresses perpendicular to the xy plane can occur (σz=σxz=σyz=0). In this option, deformation can occur in the thickness direction of the element, which will become thinner when stretched and thicker when compressed; it is generally used for objects with limited depth (thin objects).In contrast, plane strain refers to the fact that deformation can only occur in plane, which means that no out-of-plane deformation will occur (ϵz=ϵxz=ϵyz=0). The plane strain option is generally appropriate for structures of nearly infinite length, relative to their cross section, that exhibit negligible length changes under load. The “generalized plane strain” option imposes the axial strain equal to a constant value; this condition does not reproduce the real operating condition of the magnet and is therefore excluded. The “plane stress with thickness” uses the same equations as the plane stress option but, output quantities are given per unit length defined with thickness; therefore, it is again excluded from the comparison. Superconducting magnets, such as dipoles, do not fit neatly into any of the above options: they are far from thin but deform longitudinally under load. This work reports a comparative study of plane stress and plane strain in the specific case study of a dipole magnet.

Radiological features of dropped head syndrome.

This study aimed to elucidate the specificity of the radiological features of Dropped head syndrome (DHS) from both reginal and global aspects. We enrolled 53 patients with DHS (8 men, 45 women; mean age 73.5 years), and captured their lateral spinopelvic radiographs in standing position. We also selected 21 age- and sex-matched controls with cervical spondylosis. Radiological parameters were measured and compared between two groups. Compensatory and decompensatory sites were also listed for each patient. Radiological factors such as sagittal vertical axis (SVA), clivo-axial angle (CAA), C2-7 angle, C2-7 SVA, anterior slippage of the vertebra, alignment. C1, C2, C3, C4, C5, C6 slopes, and T1 slope-C2-7 angle showed statistically significant differences between the groups. Multivariate logistic regression showed that SVA, C2-7 SVA, T1-slope-C2-7 angle, and C1 slope were the most important factors specific to DHS. Sole cervical spine and involvement of both cervical and thoracic spine accounted for 22% and 29% of the decompensatory sites in DHS respectively. Notably, 24% of the patients did not show decompensation of the cervical spine. While, 93% exhibited compensation at the craniovertebral junction. The thoracic spine contributed 70% to DHS compensation. This study indicated the radiological features of DHS from both regional and global aspects. Compensatory and decompensatory DHS mechanisms varied among individuals. Compensation was likely to be developed at the neighboring sites, with the craniovertebral and thoracic junctions as the proximal and distal parts for DHS, respectively.

Blade Airfoil Optimization and Its Impact on Vertical Axis Wind Turbine Performance

Abstract Amidst the emergence of crises in petroleum prices and supply, the imperative for the development of clean energy has become increasingly apparent. Vertical axis wind turbines (VAWT), as a type of wind turbine, still grapple with challenges such as low wind energy utilization and sensitivity to dynamic wind speeds. This study focuses on optimizing the airfoil of a two-dimensional vertical axis wind turbine and analyzes the performance variations in a three-dimensional model. Following the optimization, the average power coefficients of the dual-blade two-dimensional VAWT increased by 7.9% and 4%, respectively, while those of the dual-blade three-dimensional model rose by 7.9% and 1.2%. However, the performance of the three-dimensional model was compromised due to the influence of tip vortices, resulting in inferior performance compared to the two-dimensional model. Both three-dimensional optimized blade designs exhibited a substantial reduction in the flow separation region downstream and improved pressure distribution fluctuations caused by the shedding of tip vortices, leading to decreased pressure differentials. Along the spanwise section, the power coefficient gradually decreased from the central segment to the tip segment. Notably, the power coefficient of the optimized blades at the tip segment increased significantly, accompanied by an augmented pressure differential between the upper and lower surfaces. This augmentation contributed to a significant enhancement in lift, thereby facilitating the rotation of the vertical axis wind turbine.

How global spine sagittal alignment and spinal degeneration affect locomotive syndrome risk in the elderly.

The aim of this study was to delineate the features of the locomotive syndrome (LS) risk stage in the elderly population, encompassing global spine sagittal alignment, visible spinal degenerative changes on plain radiographs, muscle strength, physical capabilities, and low back pain (LBP). The study enrolled 232 subjects, evaluated using plain radiographs. The evaluation included measurements of lumbar lordosis (LLA), thoracic kyphosis (TKA), spinal inclination (SIA) angles, and sagittal vertical axis. Assessments included lumbar osteophyte formation (LOF) and lumbar disc height (LDH) to examine spinal degenerative changes. LS evaluation used the locomotive syndrome risk test based on LS risk criteria, classifying participants into no risk, stage 1 LS, and stage 2 LS groups. Using a visual analogue scale (VAS), we investigated the prevalence of low back pain (LBP) and assessed physical performances across these groups. There were 132 participants with no LS risk, 71 with stage 1 LS risk, and 29 with stage 2 LS risk. As LS risk increased, LBP prevalence and VAS scores rose, physical abilities, and back muscle strength decreased. TKA showed no variation across groups, while LLA decreased with advancing LS risk stage. Except for L1-L2 and L5-S1, lumbar disc height (LDH) decreased with higher LS risk stages. LOF occurrence increased notably with higher LS risk stages. Spinal inclination angle (SIA) significantly increased with advancing LS risk stages. Participants diagnosed with LS exhibited an increased incidence of spinal degeneration, reduced LLA, and global spinal imbalance characterized by anterior spinal inclination.

Enhancing visual seismocardiography in noisy environments with adaptive bidirectional filtering for Cardiac Health Monitoring

BackgroundWearable sensors have revolutionized cardiac health monitoring, with Seismocardiography (SCG) at the forefront due to its non-invasive nature. However, the substantial motion artefacts have hindered the translation of SCG-based medical applications, primarily induced by walking. In contrast, our innovative technique, Adaptive Bidirectional Filtering (ABF), surpasses these challenges by refining SCG signals more effectively than any motion-induced noise. ABF leverages a noise-cancellation algorithm, operating on the benefits of the Redundant Multi-Scale Wavelet Decomposition (RMWD) and the bidirectional filtering framework, to achieve optimal signal quality.MethodologyThe ABF technique is a two-stage process that diminishes the artefacts emanating from motion. The first step by RMWD is the identification of the heart-associated signals and the isolating samples with those related frequencies. Subsequently, the adaptive bidirectional filter operates in two dimensions: it uses Time-Frequency masking that eliminates temporal noise while engaging in non-negative matrix Decomposition to ensure spatial correlation and dorsoventral vibration reduction jointly. The main component that is altered from the other filters is the recursive structure that changes to the motion-adapted filter, which uses vertical axis accelerometer data to differentiate better between accurate SCG signals and motion artefacts.OutcomeOur empirical tests demonstrate exceptional signal improvement with the application of our ABF approach. The accuracy in heart rate estimation reached an impressive r-squared value of 0.95 at − 20 dB SNR, significantly outperforming the baseline value, which ranged from 0.1 to 0.85. The effectiveness of the motion-artifact-reduction methodology is also notable at an SNR of − 22 dB. Consequently, ECG inputs are not required. This method can be seamlessly integrated into noisy environments, enhancing ECG filtering, automatic beat detection, and rhythm interpretation processes, even in highly variable conditions. The ABF method effectively filters out up to 97% of motion-related noise components within the SCG signal from implantable devices. This advancement is poised to become an integral part of routine patient monitoring.

Fault Diagnosis of Wind Turbine Blades with Continuous Wavelet Transform based Deep Learning Model Using Vibration Signal

Wind Turbines are the most crucial devices in wind energy conversion systems to increase energy generation efficiency from wind sources. Blade failure in wind turbines is due to the induced vibrations of change in ecological variables. It is necessary to periodically inspect the state of the wind turbine blades to enhance safety by decreasing downtime, lessening the likelihood of unplanned failures requiring extensive repair, and progressively increasing power generation with reduced logistical costs. The primary goal of the proposed research is to adopt a hybrid strategy that combines convolutional neural network models and continuous wavelet transform. The bump wavelet-based continuous wavelet transform with a convolutional neural network model is employed to classify the faulty wind turbine blades based on the extracted vibration signals of turbine blades. This approach distinguishes between different states of blade faults affecting wind turbine blades during operational phases. The research considers blade faults in the horizontal axis wind turbine, including blade bending, erosion, and the connection looseness between the hub and blade. The cross-validation and hold-out methods are used to validate the classification accuracy and are compared with other existing popular methods. The hold-out method has a better classification accuracy of 97.916%.

Optimization Design of Bionic Leading-edge Protuberances on Horizontal Axis Wind Turbine Blades

Abstract The complex operating environments of horizontal axis wind turbines has made the phenomenon of blade flow separation more obvious. As a passive flow control method, the bionic humpback whale leading-edge protuberances have been shown to effectively enhance the performance of the wind turbine. This study employs a multi-objective genetic algorithm and Computational Fluid Dynamics method to analyse the impact of leading-edge protuberances on the aerodynamic performance and flow characteristics of the blades. The results indicate a significant improvement in blade performance after optimization in the wind turbine’s output power. The streamwise vortices generated by the bionic protuberances not only reduce the suction surface pressure, but also suppress the spanwise flow over the blade surface. The length of the flow separation Region is reduced from 0.410 to 0.368 radius. In the process of wind speed change, the tangential forces on the bionic blade exhibit a wave-like variation. The bionic protuberance alters the pressure coefficient of the position. Compared with the original blade, the pressure coefficient of the trough sections on both sides of the bionic blade protuberance is improved. In this study, the bionic protuberance applied to the leading-edge of horizontal-axis wind turbine blades is proposed for the first time, and holds practical value for guiding practical applications.

Research of Acoustic Emission Characteristics and Applicability of Artificial Intelligence for Source Localization

Within this research, the deployment of artificial intelligence for the localization of acoustic emissions (AE) is being investigated. In detail, series of experiments were conducted on a plate of granite with homogeneous and isotropic material behavior. Acoustic emissions could be generated by the breaking of pencil leads, as well as the impact of rice grains and steel balls on 81 specific positions with a distance of 50 mm in both horizontal axes to each other. The response of the system was recorded using 16 acoustic emission sensors, of which 8 sensors were positioned on each surface side of the plate. In further steps the data could be processed, so that the resulting characteristic signal features could be translated into spec-trograms and furthermore being used as input for the artificial intelligence. Additionally, the corresponding source locations appeared as labels. Both, the signal features as well as the labels, could be implemented in the process of supervised learning using a convolutional neural network (CNN). The results of this network indicated a validation accuracy of over 99% as well as a low loss value by classifying the inserted features to the right labels. Thus demonstrates the excellent applicability of artificial intelligence for the source localization of acoustic emission (AE).

Fluid flow and heat transfer of a novel passive cooling system for gearless wind turbines with a power range of 3–12 MW

Today, the gearless horizontal axis wind turbines are mainstream in wind energy industry. High demands of electric power led to bigger systems and active cooling reduces the overall efficiency of the turbines. Passive cooling systems have been examined for the first time for a gearless wind energy generator with power range of 3–12 MW. With further developed heat conductors, it is possible to operate a wind generator in a larger power class with passive cooling components. This is accompanied by enormous cost savings due to elimination of costs for active cooling elements such as the use of fans, pumps, and heat exchangers. An additional factor is the significant reduction in necessary maintenance due to the minimized incidence of corrosion and wear. Design of the cooling fins and an ideal position of the generator within the housing of the wind turbine has been objectives. Mandatory is that maximum temperatures of the generator fins should stay under 155 °C, which could be reached with several designs for different heat exchanger geometries.

Addressing the non-perturbative regime of the quantum anharmonic oscillator by physics-informed neural networks

Abstract The use of deep learning in physical sciences has recently boosted the ability of researchers to tackle physical systems where little or no analytical insight is available. Recently, the Physics−Informed Neural Networks (PINNs) have been introduced as one of the most promising tools to solve systems of differential equations guided by some physically grounded constraints. In the quantum realm, such an approach paves the way to a novel approach to solve the Schrödinger equation for non-integrable systems. By following an unsupervised learning approach, we apply the PINNs to the anharmonic oscillator in which an interaction term proportional to the fourth power of the position coordinate is present. We compute the eigenenergies and the corresponding eigenfunctions while varying the weight of the quartic interaction. We bridge our solutions to the regime where both the perturbative and the strong coupling theory work, including the pure quartic oscillator. We investigate systems with real and imaginary frequency, laying the foundation for novel numerical methods to tackle problems emerging in quantum field theory.

Accounting for the expansion of the universe using an energy/momentum model to construct the space-time metric

Background The success of the theories of special and general relativity in describing localised phenomena, such as objects undergoing high speed motion or located in gravitational fields, needs no further elaboration. However, when applied to the evolution of the universe several problems arise which can require an additional model, e.g., inflation during the early expansion, and adjustments to parameters to account for phenomena such as the late-time acceleration of the universe. Methods Focusing on the difference between the ways in which space and time are measured, this paper shows that there are two paths which allow the equations of special relativity to be produced from the same basic postulates. Results Both the standard theory and the energy/momentum, or dynamic model, utilise the Minkowski metric, but with different coordinate systems. The dynamic model transforms Cartesian coordinates into an Euclidean form by multiplying the coordinates by functions of γ (=(1–ν 2)c 2)-1⁄2). When utilising these coordinates, the relativistic equations are unchanged for local phenomena such as the Lorentz coordinate transformation and the energy/momentum equation for high-velocity objects. Conclusions However, the derived coordinates alter the perceived overall structure of the universe in a manner that, for the simplest model under this system, allows the reproduction of observed cosmological features, such as the intrinsic flatness of the universe and the apparent late-time acceleration of its expansion, without the need of additional models or changes in parameter values.

Different Degeneration Patterns of Paraspinal Muscles Between Double-Level and Single-Level Lumbar Spondylolisthesis: An Magnetic Resonance Imaging Analysis of 140 Patients.

To evaluate the degeneration patterns of paraspinal muscles in double-level degenerative lumbar spondylolisthesis (dl-DLS) versus single-level degenerative lumbar spondylolisthesis (sl-DLS). A total of 67 dl-DLS and 73 sl-DLS patients were included. Multifidus (MF), erector spinae (ES), and psoas major (PM)'s fatty infiltration (FI) and relative cross-sectional area (rCSA) were measured. Sagittal parameters such as lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) were also assessed. Comparisons and correlation analysis were performed between the 2 groups. MF atrophy is worse in dl-DLS patients from L3-4 to L5-S1, with higher FI from L1-2 to L5-S1 compared to sl-DLS patients. ES atrophy and FI are more pronounced in dl-DLS patients from L1-2 to L5-S1. PM atrophy is more significant in dl-DLS patients at L2-3 to L5-S1, with heavier FI from L1-2 to L3-4, though no difference in FI from L4-5 to L5-S1. The rCSA and FI of MF and ES show significant differences between adjacent segments in both groups, except for MF rCSA between L3-4 and L4-5 in dl-DLS. In dl-DLS, PM rCSA negatively correlates with PT from L4-5 to L2-3, while FI of MF and ES in L5-S1 positively correlates with LL. In sl-DLS, PM FI in L4-5 and L5-S1 negatively correlates with LL. Degeneration of MF, ES, and PM is more severe in dl-DLS patients, particularly at the spondylolisthesis level. Severe paraspinal muscle degeneration can lead to spinal force imbalance and progression from sl-DLS to dl-DLS. The degradation of PM and ES correlates negatively with PT and SVA, indicating a link to pelvic decompensation and SVA abnormalities, potentially causing disproportionate degenerative changes in dl-DLS patients.

Design and dynamic emulation of hybrid solar-wind-wave energy converter (SWWEC) for efficient power generation.

As research into wave energy converters progresses and new developers enter the field, there arises a growing requirement for a standardized modelling approach. This article presents a novel design and dynamic emulation for a hybrid solar-wind-wave energy converter (SWWEC) which is the combination of three very well-known renewable energies: solar, wind and wave energy. Photovoltaic (PV) panels and vertical axis wind turbine (VAWT) are installed on top of the floating WEC that harness the energies from the sun and wind respectively. The SWWEC is designed with a point absorber capture system. An electrical motor is used to dynamically emulate the performance of the SWWEC under real world conditions to drive the DC generator. The present paper shows the importance and necessity of the required control schemes for the proper control of generator side converters which is present in the offshore marine substation and the most required grid connected onshore converters. The better switching signal generation for the converter control and generated harmonics elimination techniques are also presented in the paper. Outcomes of the present study are discussed and verified.