Central Angle Research Articles

Understanding the behaviour of magnetic field distribution of railgun under transient conditions using finite element method

The magnetic field distribution in the rails is a crucial factor in comprehending railgun behaviour. The projectile's rapid movement has a significant impact on the magnetic field. If the dispersion of the magnetic field conclusions regarding the conductors are known suitable methods can be used to sketch the magnetic field distribution. The railgun operates on the premise that a high current flow through the rails and armature will create a strong magnetic field. As a result, before designing magnetic shielding, it is necessary to study the features of the magnetic field distribution. The shape of rail and armature cross section is very essential in rail gun design as it determines the magnetic field distribution over rail and armature. The rail gun geometries with rectangular, convex and concave rail cross-sections are compared and simulated using finite element method (FEM). This method is used to determine the magnetic field distribution over rail and armature by sweeping armature position for different rail cross sections. It is observed that for the different rail/armature shapes like rectangular, convex and concave shapes, the C shaped convex armature possesses strong magnetic fields with minimum current density concentration at the throat and trailing end of the armature. From simulation, it can be shown that the magnetic flux density is a descending function of the central angle. The electromagnetic (EM) rail gun launching mechanism was therefore proven to be compatible with the circular concave armature.

Semi-analytical dynamic modeling and fluid-structure interaction analysis of L-shaped pipeline

The traditional semi-analytic modeling is mainly aimed at the straight pipeline with simple boundary conditions. In contrast, the actual aero-engine pipeline needs to consider the effects of complex configuration, boundary and multiple clamps, so proposing an improved semi-analytic method to model an arbitrary fluid-conveying L-shaped pipeline is challenging. Based on the Hamiltonian principle, the differential equations of the L-shaped pipeline are derived. Then, the modal shape functions are determined under the conditions that the elastic support points and the joints of the straight pipeline and the curved pipeline meet the deformation coordination requirements. The proposed semi-analytical model is verified by comparing the natural frequencies and mode shapes obtained from the finite element method using ANSYS and experiment; the error of each order natural frequency is less than 5 %. In addition, the model is verified under various working conditions: different center angle and boundary conditions (clamp position and pipeline end constraints). The effects of the fluid velocity and pressure on the natural characteristics of the L-shaped pipeline are also analyzed. The results show that under the critical pressure of 60.51 MPa and the critical velocity of 247 m/s, the natural frequency decreases with the increase of fluid velocity and pressure. The proposed method can provide theoretical support for efficient and accurate modeling of complex spatial pipeline systems.

Determining optimal bead central angle by applying machine learning to wire arc additive manufacturing (WAAM)

Wire arc additive manufacturing (WAAM) is being extensively used in various industrial fields. In WAAM, if a bead is deposited without considering the central angle, its shape may collapse with increasing number of layers. To address this problem, a new method for optimizing the bead geometry using a support vector machine (SVM) classifier was established in this study. The ranges of the optimal deposition conditions were determined using the SVM classifier and verified by experiments. Geometric data of deposited beads were extracted using a laser profiler, and an SVM binary classifier was used to predict suitable ranges of the deposition conditions. Data were extracted through 20 single-layer basic experiments, classification was performed based on 4°, and the appropriateness of SVM classification was found through 8 single-layer and 3 multi-layer verification experiments.The results showed that the SVM classifier successfully selected the ranges of the optimal deposition conditions. Verification experiments revealed that the results in all cases were appropriately classified based on the boundary of the classification line. Moreover, the SVM classifier was efficient even when a small amount of input data was available. The contribution of this study is that the developed method can help build desired bead geometries in scenarios where deposition is required in the WAAM process, such as re-manufacturing. Thus, this method can be used in real-world industrial applications through further research on the bead shape with multi-layer deposition.

The impact of conduction anesthesia at the hemostastic system in the limb reperfusion syndrome in pediatric traumatology-orthopedic practice

Introduction. Activation of the hemostatic system in the ischemia-reperfusion syndrome is a risk factor for thromboembolic complications during orthopedic surgical interventions associated with arterial tourniquet application. Therefore, it is relevant to find ways to mitigate reperfusion effects during such surgeries.
 Purpose. To find out character and effects of conduction anesthesia at the thromboelastogram parameters in the ischemic limb reperfusion after removing a tourniquet during orthopedic surgeries in children.
 Material and methods. The surgery which was performed in 20 patients from the traumatologic department in the City Children’s Clinical Emergency Hospital (Novosibirsk) required arterial tourniquet application. So, these patients were enrolled in the observational pilot study. The patients who had tourniquet application were distributed into two groups by the block randomization: Group 1 (n=10) – peripheric blockage; Group 2 (n=10) – no peripheric blockage. The basic technique used in the study was thromboelastography (TEG) with TEG5000 thromboelastograph (Haemonetics Corporation, USA). All patients had thromboelastography before tourniquet application (stage 1) and 5 minutes after its removal (stage 2). Main thromboelastogram parameters were assessed: R, measuring pathways for coagulation phases I and II; K – time, characterizing coagulation phase III; angle α, duplicating the information of “K” indicator; MA is the maximum amplitude of TEG branch divergence, characterizing the clot density which, in turn, depends on the function of platelet activity and on the amount of fibrinogen; LY30 is the percentage of clot lysed in 30 minutes.
 Results. In the group with regional anesthesia, indicators R, K, angle α, MA did not change at stage II; LY30 index decreased at stage 2. In the group without regional anesthesia, but with powerful central analgesic, indicators R, K, MA decreased, and angle α and LY30 increased at stage 2.
 Conclusion. In pediatric orthopedic surgeries with arterial tourniquet application , local anesthetic (Ropivacaine) in the conduction anesthesia technique prevented activation of the hemostastic system.

A Unified Representation for Fundamental Equations of Various X-Ray Stress Measurement Methods

The X-ray stress measurements by the sin2ψ method, the cos α method and the XRD2 method are basically composed of the fundamental equations based on diffraction vectors and the calculation for determining X-ray stress. The fundamental equations are expressed differently, which are due to the fact that the measurement systems associated with the incident X-ray control device and the diffracted X-ray detector are different. Although the dependent variable that is the measured quantity is the same diffraction angle theta in the fundamental equations, the main independent variable is different like the tilt angle ψ in the sin2 ψ method and the central angle α, γ of the Debye-Scherrer ring in the cos α method, the XRD2 method, respectively. Therefore, the stress determination method has been devised based on each the fundamental equation. By clarifying the differences between each X-ray stress measurement method and making a relationship, a unified representation for the fundamental equations is formalized. Therefore, a comparison of each X-ray stress measurement method is expressed in the same Euler space, and a conversion method for each X-ray stress measurement method is presented.

Nonlinear static bending and dynamic behaviors of graphene platelets reinforced dielectric porous arches

This paper comprehensively investigates the electro-induced nonlinear static bending and vibration behaviors of the graphene platelets reinforced dielectric porous (GPLRDP) arches. The effective dielectric permittivity and Young's modulus of GPLRDP composites are determined based on the effective medium theory (EMT). The nonlinear governing equations for the GPLRDP arch under the electrical voltage are derived by using the Hamilton principle and are numerically solved by utilizing the differential quadrature method (DQM) together with an iterative scheme to obtain its electro-induced nonlinear static bending and dynamic responses. The influences of the porosity, GPL concentration, boundary condition, central angle, and DC and AC voltage on the nonlinear behaviors of the GPLRDP arch are discussed in detail. It is found that the addition of GPLs has significant effects on the electro-induced mechanical behaviors of the GPLRDC arch when the GPLs weight fraction exceeds the percolation threshold. Numerical analysis proves that the electro-induced static and dynamic behaviors of the GPLRDC arch can be designed and actively tuned through adjusting material and structural parameters, providing valuable insights for the development of smart GPLRDP arches.

SAR-ATR with knowledge hierarchy division and information dissemination networks

Synthetic aperture radar (SAR) images possess diverse domain characteristics that describe targets from multiple perspectives, including scattering center, intensity, phase, azimuth angle, and shadow. The imaging mechanism of SAR images significantly differs from optical images due to its use of radio waves instead of visible light for imaging purposes. However, current deep learning (DL)-based automatic target recognition (ATR) approaches for SAR primarily focus on the intensity information while neglecting the comprehensive consideration of SAR domain characteristics. This limitation results in insufficient expression of target features and hampers further improvement in SAR target recognition performance. To address these issues, this paper proposes a novel SAR target recognition method called KDNets based on information dissemination networks (IDNets) and knowledge hierarchy division (KnHD). KDNets effectively enhances the feature representation ability of SAR targets by exploiting multiple domain characteristics at sample, feature, and decision levels. Specifically, IDNets incorporates scattering center and azimuth angle at sample and feature levels to extract rich multi-scale semantic features for representing SAR targets. At the decision stage, KnHD utilizes azimuth information to rapidly search and fuse prior knowledge about targets from a knowledge base to achieve interpretable and high-precision SAR target recognition. Experimental results on the MSTAR dataset and MA-SAR dataset demonstrate that our proposed KDNets can achieve state-of-the-art performance in SAR target recognition tasks, with the accuracy of 99.75 % in the MSTAR dataset and 98.61 % in the MA-SAR dataset, validating its effectiveness and superiority. Furthermore, this study highlights the significant potential and application prospects of leveraging domain characteristics in SAR-ATR tasks.

Free Vibration Analysis of Arches with Interval-Uncertain Parameters

The dynamic characteristics of a structure serve as a crucial foundation for structural assessment, fault diagnosis, and ensuring structural safety. Therefore, it is imperative to investigate the impacts of uncertain parameters on the dynamic performance of structures. The dynamic characteristics of arches with uncertain parameters are analyzed in this paper. The uncertain parameters are regarded as non-probabilistic uncertainties and represented as interval variables. A model of an arch considering interval-uncertain parameters is built, and kinematic equations are established. The natural frequencies are obtained using the differential quadrature (DQ) method, and the relationships between natural frequency, radius, and central angle are also analyzed. On this basis, the Chebyshev polynomial surrogate (CPS) model is employed to solve the uncertain dynamic problem, and the natural frequencies are seen to be the objective functions of the CPS model. The accuracy verification of the model is achieved by comparison with the Monte Carlo simulation (MCS). Simulations are carried out considering different uncertainties, and the results show that the bounds of natural frequencies are influenced not only by the types of uncertain parameters, but also by their combinations.

An efficient multi-objective optimization framework for thin-walled tubular deployable composite boom

As a crucial structural component in space applications such as solar sails and solar arrays, the thin-walled tubular deployable composite booms (DCBs) demonstrate extensive utilization by employing stored elastic strain energy to achieve folding and deploying functions. This paper introduces a multi-objective optimization framework that integrates an analytical model with a genetic algorithm. By utilizing a multi-objective evolutionary algorithm based on de-composition (MOEA/D), the optimization objectives of minimizing folding moment and maximizing bending stiffness are pursued. Multiple constraints associated with failure avoidance, laminate stacking sequence design principles, and the folding moment range of actuator in the folding mechanism are considered in the optimization. The multi-objective optimization design of the tubular DCBs is performed to obtain the optimal combinations of cross-sectional radius, central angle, and ply scheme. Experimental validation confirms the efficacy of the optimization results. Additionally, an in-depth analysis on the influence of genetic algorithm types, hyperparameters, and different design variables on the optimization outcomes is thoroughly discussed. The findings of this study offer significantly insights for the practical engineering applications of tubular DCBs.

Abstract 17943: Biomechanical Finite Element Analysis of Asymmetric Bicuspid Aortic Valve With Different Commissure Positionings for Repair

Introduction: While bicuspid aortic valves (BAVs) exist with a wide variety of phenotypes, type 1 valves that require surgery often present with varying levels of cusp fusion, raphe geometry, and commissure positioning angles. Regarding central coaptation angle, BAVs commonly present with asymmetry between fused and non-fused cusps, and surgical debate focuses on whether BAV repair should aim to minimize or accommodate for this asymmetry. We aimed to compare the hemostatic structural integrity of different commissure positionings for repair based on a BAV with an original 150° central angle. Methods: BAV models were designed based on literature of asymmetric valve geometry. The central angle of the pathological valve was 150°, which is common (Fig A). Two subsequent valve geometries were modeled to represent the repair conditions where commissure positioning forces result in central angles of 165° (Fig B) and 180° (Fig C). These models were matched with leaflet surface area and implemented with mechanical parameters of aortic leaflet tissues. Coaptation planes were modeled as encastre boundaries. A hemostatic pressure gradient was applied at 90 mmHg to mimic peak diastolic pressures, and Fusion360 was used for finite element simulations. Results: All three models showed maximum von Mises stresses in the belly regions of the fused leaflet (Fig A-C). Upon running the simulations, the 150° model showed maximum Von Mises stresses of 8103 Pa, the 165° model showed maximum stresses of 5405 Pa, and the 180° model showed stresses of 6116 Pa. Conclusions: By leveraging finite element models and computational biomechanics analyses, we were able to identify differences in BAV leaflet stresses based on alternate commissural positioning of an asymmetric BAV phenotype. Our finding suggests that peak diastolic leaflet forces may be minimized by focusing surgical BAV repair on a moderate reduction of leaflet asymmetry (i.e., 150° to 165°), without imposing perfect symmetry.

Dimensional synthesis of motion generation in a spherical four-bar mechanism

A new objective function for optimizing spherical, four-bar mechanisms for motion generation is presented. Rigid-body poses of a spherical four-bar mechanism in a standard installation position are investigated, and a normalization processing method is proposed. After processing the coupler points of the mechanism, the feature points generated are located on the circles. The formation principle of the feature coupler circles is analysed, and the internal relationship between the centre angle of the adjacent feature points on the feature coupler circles and the coupler angle of the spherical four-bar mechanism is determined. An input angle determination method is proposed for the spherical four-bar mechanism in a general installation position. An objective function is then established to optimize the basic dimensional types, relative input angles, and installation position parameters of the desired spherical four-bar mechanism. The proposed method is applicable to both prescribed and unprescribed timing problems. Notably, the dimension of the optimization variables is only eight, which is exceptionally low for multiple position motion generation without prescribed timing; therefore, the global optimal solution is more easily obtained. The optimization process is carried out by the genetic algorithm. The feasibility and effectiveness of our proposed method are demonstrated by examples.

Characteristic changes of blood stasis syndrome in rat model of steroid-induced femoral head necrosis based on the combination of disease, syndrome, and symptom

The approach combining disease, syndrome, and symptom was employed to investigate the characteristic changes of blood stasis syndrome in a rat model of steroid-induced osteonecrosis of the femoral head(SONFH) during disease onset and progression. Seventy-two male SD rats were randomized into a healthy control group and a model group. The rat model of SONFH was established by injection of lipopolysaccharide(LPS) in the tail vein at a dose of 20 μg·kg~(-1)·d~(-1) on days 1 and 2 and gluteal intramuscular injection of methylprednisolone sodium succinate(MPS) at a dose of 40 mg·kg~(-1)·d~(-1) on days 3-5, while the healthy control group received an equal volume of saline. The mechanical pain test, tongue color RGB technique, gait detection, open field test, and inclined plane test were employed to assess hip pain, tongue color, limping, joint activity, and lower limb strength, respectively, at different time points within 21 weeks of modeling. At weeks 2, 4, 8, 12, 16, and 21 after modeling, histopathological changes of the femoral head were observed by hematoxylin-eosin(HE) staining and micro-CT scanning; four coagulation items were measured by rotational thromboelastometry; and enzyme-linked immunosorbent assay(ELISA) was employed to determine the levels of six blood lipids, vascular endothelial growth factor(VEGF), endothelin-1(ET-1), nitric oxide(NO), tissue-type plasminogen activator(t-PA), plasminogen activator inhibitor factor-1(PAI-1), bone gla protein(BGP), alkaline phosphatase(ALP), receptor activator of nuclear factor-κB(RANKL), osteoprotegerin(OPG), and tartrate-resistant acid phosphatase 5b(TRAP5b) in the serum, as well as the levels of 6-keto-prostaglandin 1α(6-keto-PGF1α) and thromboxane B2(TXB2) in the plasma. The results demonstrated that the pathological alterations in the SONFH rats were severer over time. The bone trabecular area ratio, adipocyte number, empty lacuna rate, bone mineral density(BMD), bone volume/tissue volume(BV/TV), trabecular thickness(Tb.Th), trabecular number(Tb.N), bone surface area/bone volume(BS/BV), and trabecular separation(Tb.Sp) all significantly increased or decreased over the modeling time after week 4. Compared with the healthy control group, the mechanical pain threshold, gait swing speed, stride, standing time, and walking cycle of SONFH rats changed significantly within 21 weeks after modeling, with the greatest difference observed 12 weeks after modeling. The time spent in the central zone, rearing score, and maximum tilt angle in the open field test of SONFH rats also changed significantly over the modeling time. Compared with the healthy control group, the R, G, and B values of the tongue color of the model rats decreased significantly, with the greatest difference observed 11 weeks after modeling. The levels of total cholesterol(TC), total triglycerides(TG), low-density lipoprotein-cholesterol(LDL-C), and apoprotein B(ApoB) in the SONFH rats changed significantly 4 and 8 weeks after modeling. The levels of VEGF, ET-1, NO, t-PA, PAI-1, 6-keto-PGF1α, TXB2, four coagulation items, and TXB2/6-keto-PGF1α ratio in the serum of SONFH rats changed significantly 4-16 weeks after modeling, with the greatest differences observed 12 weeks after modeling. The levels of BGP, TRAP5b, RANKL, OPG, and RANKL/OPG ratio in the serum of SONFH rats changed significantly 8-21 weeks after modeling. During the entire onset and progression of SONFH in rats, the blood stasis syndrome characteristics such as hyperalgesia, tongue color darkening, gait abnormalities, platelet, vascular, and coagulation dysfunctions were observed, which gradually worsened and then gradually alleviated in the disease course(2-21 weeks), with the most notable differences occurred around 12 weeks after modeling.

Correlation of Steam Velocity and Pipe Diameter with Heat Transfer Performance on 120° Half-Pipe Jacket

Double jacket mixing tanks offer temperature control and versatility for industrial processes where temperature-sensitive materials need to be mixed, stored, or processed. The selection of the appropriate jacket type in a double-jacket mixing tank is based on the structural strength and the optimal heat transfer performance. The type of jackets can be conventional, dimple, and half-pipe. The conventional jacket is easier to manufacture, but it is not resistant to high temperature and pressure. The dimple jacket has good heat transfer, but it is susceptible to damage. The half-pipe jacket has good structural strength, but its heat transfer is affected by the central angle and pipe diameter. 120° central angle has greater heat transfer and pressure drop than 180° central angle. In order to determine the effects of steam velocity on heat transfer performance, heating time, and pressure drop of the 120° half-pipe jacket, research occurred on pipes with 2, 2.5, and 3 inches of diameter. The calculating method of heat transfer in agitated jacketed vessels is applied to visualize the relationships. The effects of steam velocity on heat transfer, heating duration, and pressure drop respectively are polynomials of order 2, power, and polynomials of order 2 with an average R2 close to 1. The greater R2, the better the relationship between two variables, according to the equation. The 120° half-pipe jacket performance will be highly effective, with 1774 W, 2.1 minutes heating duration, 8.94 kPa pressure drop if the steam velocity is 10.50 m/s with 2.5 inches pipe diameter.

Numerical study of critical straight, frown, and chevron incisions in small incision cataract surgery

Introduction: When an intraocular lens (IOL) injector is inserted through a pre-cut corneal incision (e.g., an empirical size of 2.2 mm) during small incision cataract surgery, uncontrollable tearing to the corneal tissue may occur, which is highly associated with the incision shape, size, and location. The goal of this numerical study was to investigate the optimal incision scheme amongst three typical shapes, i.e., straight, frown, and chevron incisions using mechanical modeling and finite element analysis.Methods: Assuming that the damage is caused by the tissue fracture at the incision tips and is governed by the classical energy release rate (ERR) theory which compares the current ERR value subject to IOL injection and the material’s intrinsic parameter, critical ERR Gc.Results: It was found that for chevron incisions, the incision shape with an angle of 170° was superior which induced minimal ERR value, while for frown incisions, the shape with a central angle of 6° was optimal. Both chevron and frown incisions could allow a larger size of injector to inject through than a straight pre-cut. In particular, the frown incision performed the best due to its lowest corresponding ERR and easy operation.Discussion: It was also observed that regions where the embedded fibrils are more dispersed and exhibit high isotropy were more favorable. If necessary, the chevron incision was recommended to be more aligned with the direction exhibiting a larger modulus, for example, along the circumferential direction near the limbus. This study provides useful knowledge in operation design and a deep insight into mechanical damage to corneal wounds in small incision cataract surgery.

Elucidation of the visualization process and its influencing factors for the preparation of microcircuits based on arc-beam laser-induced forward transfer

Arc beam laser-induced forward transfer (AB-LIFT) based on an arc beam is a promising micro additive manufacturing process to efficiently prepare high-performance metal microcircuits by transferring metal microdroplets. Therefore, elucidating the transfer mechanism of arc-beam-induced microdroplets is crucial to controlling the printing process. In this paper, a dark-field imaging system is developed to visually analyze the transfer process of metal microdroplets, and the injection mechanism of Gaussian and arc-beam laser-induced forward transfer is analyzed. Meanwhile, by studying the deposition behavior of laser-induced forward transfer micro drops with an arc beam at a single pulse energy, it is concluded that the factors affecting the laser-induced forward transfer with an arc beam mainly include the center angle and diameter of the arc beam. Then the effects of the center angle and diameter of the arc beam and the laser parameters on the preparation of microcircuits by AB-LIFT are systematically investigated, and a set of process methods for the effective preparation of high-performance microcircuits is proposed.

Curved woven lattice truss sandwich panels strengthened by foams: Designing, manufacturing, and testing

AbstractThe woven lattice truss sandwich panels (WLTSPs) have been studied much, and this article proposes a new structure (curved woven lattice truss sandwich [CWLTS] panels). CWLTS were designed, made, and tested. The foam‐filling technique was applied to strengthen the CWLTS. Curving and foam‐filling effects to the deformation, damage, failure, and energy absorption under cylindrical and plated loadings were revealed by three‐point bending experiments. Under cylindrical loading, foam‐filling can effectively increase the load capacity, especially the CWLTS‐A. The load‐bearing capacity of the plated loading is greater than that of the cylindrical loading, and the phenomenon is significantly improved after foam filling, except for the central angle of 60° and the CWLTS‐A of 44.05°. Foam‐filling changes failure from core‐shearing to face fracture. For foam‐filled panels, the change in loading pattern results in energy absorption increase of 2.45 times for CWLTS‐B and 2.86 times for CWLTS‐A. Plated loading approximately doubles the peak load and energy absorption with two plastic hinges. The effect of foam filling on the mean crush force of the CWLTS plated loading is greater. The mechanical and energy absorption properties of the CWLTS can be improved by changing the loading mode and using foam filling, effectively increasing the applicability.Highlights Curved woven lattice truss sandwich panels were designed, made, and tested. Foam‐filling method greatly improves the bearing capacity of the CWLTS panels. Plated loading much increases the bearing capacity and energy absorption. The impact of curvature on mechanical performances is not immediately apparent.

The analysis of grid independence study in continuous disperse of MQL delivery system

A sustainable cutting method of Minimum Quantity Lubricant (MQL) was introduced to promote lubrication effect and improve machinability. However, its performances are very dependent on the effectiveness of its mist to penetrate deep into the cutting zone. Optimizing the MQL system requires massive experimental work that increases cost and time. Therefore, this study conducts Computational Fluid Dynamic (CFD) analysis using ANSYS Fluent and focuses on the grid independence study in dispersed-continuous phase of MQL delivery system. The main aim is to identify the best mesh model that influences the accuracy of the CFD model. The analysis proposed two different unstructured grid cell elements of quadrilateral and triangular that were only applicable for 2-dimensional fluid flow in CFD. The unstructured grid was controlled with three different mesh quality factors such as Relevance Center, Smoothing, and Span Angle Center at coarse /low, medium, and fine /high. The results showed that the best mesh quality for quadrilateral was at 60,000 nodes number and coarse mesh, whereas the triangular was at 90,000 nodes number and coarse mesh. Both combinations resulted the most consistent and reliable result when compared with past studies. However, this study decided to choose quadrilateral cell element with 60,000 nodes number and coarse mesh as it is considered to be sufficient to provide accurate and reliable result as well as practical in terms of computational time for the MQL model in CFD analysis.

Native Glenoid Depth and Hill-Sachs Lesion Morphology in Traumatic Anterior Shoulder Instability

Background: Although Hill-Sachs lesions (HSLs) are assumed to be influenced by glenoid characteristics in the context of bipolar bone loss, little is known about how glenoid concavity influences HSL morphology. Purpose: To investigate the relationship between the native glenoid depth and HSL morphological characteristics. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Computed tomography images of bilateral shoulders from 151 consecutive patients with traumatic unilateral anterior shoulder instability were retrospectively reviewed. Patients were categorized into flat (<1 mm), moderate (1-2 mm), and deep (>2 mm) groups based on the native glenoid depth measured from the contralateral unaffected shoulder. The HSL morphological characteristics included size (depth, width, length, and volume), location (medial, superior, and inferior extent), and orientation (rim and center angle). The glenoid characteristics included diameter, depth, version, and bone loss. The patient, glenoid, and HSL morphological characteristics were compared among the 3 depth groups. Subsequently, the independent predictors of some critical HSL morphological characteristics were determined using multivariate stepwise regression. Results: After exclusion of 55 patients, a total of 96 patients were enrolled and classified into the flat group (n = 31), moderate group (n = 35), and deep group (n = 30). Compared with those in the flat group, patients in the deep group were more likely to have dislocation (38.7% vs 93.3%; P = .009) at the primary instability and had a significantly larger number of dislocations (1.1 ± 1.0 vs 2.2 ± 1.8; P = .010); moreover, patients in the deep group had significantly deeper, wider, larger volume, more medialized HSLs and higher incidences of off-track HSLs (all P≤ .025). No significant differences were detected among the 3 groups in HSL length, vertical position, and orientation (all P≥ .064). After adjustment for various radiological and patient factors in the multivariate regression model, native glenoid depth remained the strongest independent predictor for HSL depth (β = 0.346; P < .001), width (β = 0.262; P = .009), volume (β = 0.331; P = .001), and medialization (β = −0.297; P = .003). Conclusion: The current study sheds light on the association between native glenoid depth and the morphology of HSLs in traumatic anterior shoulder instability. Native glenoid depth was independently and positively associated with HSL depth, width, volume, and medialization. Patients with deeper native glenoids were more likely to have off-track HSLs and thus require more attention in the process of diagnosis and treatment.

Kualitas Informasi Anatomi Radiograf pada Pemeriksaan Sternum dengan Variasi Penyudutan Arah Sinar

Background: The sternum's radiographic examination involves the use of Right Anterior Oblique (RAO) and Lateral projections. However, if a patient cannot undergo RAO projection, Left Posterior Oblique (LPO) projection in the supine position and adjusting the central ray angle are alternatives. On another note, deviations from perpendicular alignment among the central ray, image receptor, and object can lead to distortions in shape, impacting image quality. Hence, a study is conducted to investigate the impact of beam angle variations on the quality of anatomical information in sternum radiographs to identify the optimal angle that yields the highest quality anatomical information in sternum radiographs. Methods: This research was quantitative research employing an experimental methodology. Data collection involved employing a single-body phantom, which underwent three exposures at each of the specified angle variations Results: Based on the results of the Kruskal Wallis test, there were significant differences in the quality of radiographic anatomic information (p value 0.05). The angle with the most optimal quality of radiographic anatomical information was an angle of 25° to the left with a mean rank value of 11.00. Conclusions: There was a significant difference in the quality of radiographic anatomic information (p value 0.05). The angle with the most optimal quality of radiographic anatomic information was the angle with the highest mean rank value, which was an angle of 25° to the left.

Flame spread over convex and inclined flat surfaces

Convex surface is a general configuration in various building structures. Most studies for flame spread only investigated the flat surface type, while the flame spread over convex surface has not been addressed yet. A comparative study of convex and inclined flat surfaces was therefore performed by designing different curvatures (reflected by central angle φ) and flat-slope inclination angles (denoted by θ). The thermally thin PMMA sheet with a fixed horizontal projection length of 500 mm was chosen. The average path flame spread rate presents an exponential growth with increasing φ and θ. Moreover, the average horizontal flame spread rates of convex and inclined flat surfaces are close. For convex surface, radiant heat flux received by the sample rear increases with increasing φ. Also, two peaks of radiant heat flux occur at φ ≥ 45°. However, convective heat flux increases suddenly when θ ≥ 22.5°, in which convective heat transfer was the main mechanism. In addition, with increasing φ and θ, overall burnout rate increases for convex surface, but has an increasing first and then decreasing tendency for flat surface. The convection contribution on the pyrolysis zone is more obvious for inclined flat surface, in comparison to convex surface.