Edge Height Research Articles

Precision and efficiency unveiled: Optimizing suction blister formation through syringe edge refinement and height reduction

Precision and efficiency unveiled: Optimizing suction blister formation through syringe edge refinement and height reduction

Numerical Investigation on Dynamic Response of Carbon Fiber Honeycomb Sandwich Panels Subject to Underwater Impact Load

This study investigates the dynamic response and failure mechanisms of carbon fiber honeycomb sandwich structures under underwater impact loads using finite element numerical simulation. The geometric modeling was performed using HyperMesh, and the dynamic response simulations were carried out in ABAQUS, focusing on honeycomb core configurations with varying edge lengths, heights, and gradient forms. The Hashin damage model was employed to describe the damage evolution of the composite materials. The simulation results revealed that the dynamic response was significantly influenced by the initial shock wave pressure and the geometrical parameters of the honeycomb cells. Larger cell-edge lengths and heights generally resulted in improved energy absorption and reduced rear panel displacement. Among the different configurations, interlayer gradient honeycomb structures demonstrated superior impact resistance compared to homogeneous and in-plane gradient structures, particularly under higher initial shock wave pressures. These findings contribute to optimizing the design of carbon fiber honeycomb sandwich structures for enhanced impact resistance in relevant applications.

The impact of zygomatic buttress bone graft on nasal floor augmentation in unilateral alveolar cleft patients with late referral: A case series

PurposeThis preliminary study aimed to assess the efficacy of zygomatic buttress bone grafting for nasal floor augmentation in patients with a unilateral alveolar cleft who were referred after the optimal timetable for this surgery had elapsed. Case seriesFive patients, aged 12–18 years, with unilateral alveolar clefts were treated at Qaem Hospital, Mashhad, Iran. Initially, a mucous layer was established on the side of the cleft nose, followed by forming a bony bridge between the defect's sides through a bone graft derived from the zygomatic buttress and xenograft bone powder. Subsequently, the grafted region was covered with an absorbable collagen membrane, and the oral-side flap was sealed. Post-operative follow-ups occurred at 1 week, 1 month, and 3 months, and cone beam computed tomography (CBCT) was performed 6 months post-treatment. Discrepancy between the anterior edge height of the pyriform aperture on the healthy and cleft sides post-grafting was assessed. The average disparity between the height of the anterior edge of the pyriform aperture on the healthy side and the peak height achieved post-grafting on the cleft side was 1.90 ± 2.82 mm. ConclusionWithin the limitations of the study, it seems that zygomatic buttress is applicable for late unilateral alveolar bone grafting as an intraoral source, and is helpful in symmetric bony nasal floor reconstruction, with a good success rate.

Percutaneous pedicle screw anchored vertebral augmentation for the treatment of Kümmell disease without neurological symptoms

To explore the clinical effect of percutaneous pedicle screw anchored vertebral augmentation(PPSAVA) in the treatment of asymptomatic Kümmell disease without neurological symptoms. The clinical data of 20 patients with Kümmell disease without neurological symptoms treated with PPSAVA in our hospital from January 2019 to December 2021 were analyzed retrospectively, including 5 males and 15 females, aged 56 to 88 (74.95±9.93) years old. and the course of disease was 7 to 60 days with an average of (21.35±14.46) days. All patients were treated with PPSAVA. The time of operation, the amount of bone cement injected and the leakage of bone cement were recorded. The visual analogue scale(VAS), Oswestry disability index(ODI), vertebral body angle(VBA), anterior edge height and midline height of vertebral body were compared among the before operation, 3 days after operation and during the final follow-up. The loosening and displacement of bone cement were observed during the final follow-up. All the 20 patients completed the operation successfully. The operation time was 30 to 56 min with an average of (41.15±7.65) min, and the amount of bone cement injection was 6.0 to 12.0 ml with an average of (9.30±1.49) ml. Bone cement leakage occurred in 6 cases and there were no obvious clinical symptoms. The follow-up time was 6 to 12 months with an average of (8.43±2.82) months. The VBA, anterior edge height and midline height of of injured vertebral body were significantly improved 3 days after operation and the final follow-up(P<0.05), and the VBA, anterior edge height and midline height of of injured vertebral body were lost in different degrees at the final follow-up (P<0.05). The VAS and ODI at 3 days after operation and at the final follow-up were significantly lower than those at preoperatively(P<0.05), but the VAS score and ODI at the final follow-up were not significantly different from those at 3 d after operation(P>0.05). At the last follow-up, no patients showed loosening or displacement of bone cement. PPSAVA is highly effective in treating Kümmell disease without neurological symptoms, improving patients' pain and functional impairment, and reducing the risk of cement loosening and displacement postoperatively.

Reducing vibration and noise in honeycomb structure applied to automobile integrated water tank

This work uses modal acoustic transfer vector (MATV) technology in conjunction with vibration response analysis to determine optimal target optimization parameters for automobile integrated water tanks. The effects of square and hexagonal reinforcement honeycomb structures on the vibration damping performance of water tanks are analyzed, using an untreated smooth plane as a reference object. The study investigates the effects of honeycomb height, honeycomb length, and honeycomb thickness on the tank’s vibration damping performance. The results indicate that a hexagonal structure is more effective than a square structure in improving structural stiffness and reducing structural vibration. The height of the honeycomb structure is particularly effective in suppressing normal vibration of the structural surface, especially when the height exceeds 8 mm. A response surface model is developed based on the edge length, wall thickness, and height of the honeycomb, following the Box-Behnken central combinatorial test design principle. Considering the effect of interference of additional parts, the noise reduction is found to be most effective with a honeycomb side length L = 12 mm, height H = 4.91 mm, and wall thickness T = 2.5 mm. These parameters can be a guide for creating a new honeycomb reinforcement structure to better achieve vibration and noise reduction in automobile water tanks.

Long-term efficacy of balloon-assisted endplate augmentation combined with transforaminal pedicle screw fixation in the treatment of thoracolumbar burst fractures

Objectives: To investigate the long-term efficacy of balloon assisted endplate reduction with vertebral augmentation combined with pedicle screw fixation in the treatment of thoracolumbar burst fractures, and to compare the clinical efficacy of calcium sulfate cement (CSC) and calcium phosphate cement(CPC). Methods: This study is a retrospective cohort study.The clinical data of 39 patients with thoracolumbar burst fractures admitted to Hefei Hospital Affiliated to Anhui Medical University from November 2013 to December 2017 were retrospectively analyzed.All patients were treated with pedicle screw reduction and fixation of the injured vertebra,balloon-assisted reduction of the collapsed endplate of the injured vertebra,and artificial bone vertebral body augmentation,and the follow-up time was >5 years.There were 24 males and 15 females,aged (42.9±13.3) years (range: 29 to 56 years).According to the Frankel spinal nerve dysfunction grading standard, there were 4 cases of grade C, 7 cases of grade D and 28 cases of grade E. There were 21 cases of CSC augmentation(CSC group) and 18 cases of CPC augmentation (CPC group). X-ray and CT were performed at 1 week, 1-, 2-, 5-year after surgery and at the last follow-up, and the imaging indicators were measured, including the injured vertebra anterior edge height ratio,the injured vertebra middle height ratio,the injured vertebra wedge angle,and the sagittal plane Cobb angle. The pain visual analogue scale (VAS) and the Oswestry disability index (ODI) was used for functional evaluation, nervous function was evaluated according to the Frankel spinal nerve dysfunction grading standard.Independent sample t test was used for inter-group comparison, and paired sample t test and repeated measure ANOVA were used for intra-group comparison. Results: All operative procedures were successfully completed, no spinal nerve function damage occurred. The postoperative imaging indexes of the patients were significantly improved compared with those before surgery (all P<0.01). The follow-up time of patients was (6.7±2.8)years (range: 5 to 9 years). Among the 11 patients with symptoms of neurological impairment before surgery, 9 patients completely recovered at the last follow-up, and 2 patients recovered from Frankel grade C to D. There were no significant differences in imaging indexes between the first week after surgery and the last follow-up in the CPC group (all P>0.05), while there were significant differences in imaging indexes between the CSC group and the last follow-up (all P<0.05). CPC group was superior to CSC group in frontal height ratio, middle height ratio, wedge angle variation and sagittal Cobb angle correction loss at 2 year, 5 year after surgery and the last follow-up, with statistical significance (all P<0.05). At the last follow-up, there were no differences in VAS and ODI between the two groups (all P>0.05). After absorption of CSC in the filling area, a hardened zone was formed around the area, and the central cavity remained without bone tissue filling. CPC absorption was very slow, and the CPC group was still filled satisfactorily at the last follow-up. Conclusions: Balloon assisted endplate reduction and vertebral augmentation combined with pedicle screw fixation through the injured vertebra have good long-term efficacy in the treatment of thoracolumbar burst fractures. Compared with CSC, CPC vertebral augmentation can better maintain the shape and spinal sequence of the injured vertebra in the long term, and can effectively reduce the collapse of the space above the injured vertebra.

Scenario for the formation of vortexlike structures in a presubstorm arc, taking into account changes in the arc height during its evolution

Activity in a prebreakup auroral arc in the form of vortexlike structures, the appearance/disappearance of which is preceded by an increase/decrease in the brightness of the arc, was studied in the context of a magnetospheric substorm, large-scale ionospheric convection, the situation in the interplanetary medium, and triangulation measurements of the arc height. The structures are observed in the premidnight hours and represent a superposition of two auroral forms: a large-scale bend in the arc that outlines the polar boundary of the diffuse auroras and smaller luminous tongues of luminosity (mini-torches) elongated along the convection on the western slope of the bends. The structures as a whole move against convection, towards substorm activity to the east of the observation area. We attribute the appearance of structures to the propagation of a disturbance deep into the magnetosphere, generated as a result of interaction of the magnetopause with a solar wind inhomogeneity, on the front of which Bz turns southward. The results of triangulation measurements show that the increase in brightness in the prebreakup arc shortly before the appearance of vortexlike structures is accompanied by a decrease in the height of the lower edge of the arc, which we explain by the appearance of a parallel electric field above the arc, which accelerates the precipitating electrons. The role of such a field in the formation of the torchlike structures is discussed in the framework of the interchange instability of the pole boundary of diffuse auroras.

Improved unilateral puncture PVP based on 3D printing technology for the treatment of osteoporotic vertebral compression fracture

To investigate the clinical effect of unilateral percutaneous vertebroplasty (PVP) combined with 3D printing technology for the treatment of thoracolumbar osteoporotic compression fracture. A total of 77 patients with thoracolumbar osteoporotic compression fractures from October 2020 to April 2022 were included in the study, all of which were vertebral body compression fractures caused by trauma. According to different treatment methods, they were divided into experimental group and control group. Thirty-two patients used 3D printing technology to improve unilateral transpedicle puncture vertebroplasty in the experimental group, there were 5 males and 27 females, aged from 63 to 91 years old with an average of (77.59±8.75) years old. Forty-five patients were treated with traditional bilateral pedicle puncture vertebroplasty, including 7 males and 38 females, aged from 60 to 88 years old with an average of(74.89±7.37) years old. Operation time, intraoperative C-arm X-ray times, anesthetic dosage, bone cement injection amount, bone cement diffusion good and good rate, complications, vertebral height, kyphotic angle (Cobb angle), visual analogue scale(VAS), Oswestry disability index (ODI) and other indicators were recorded before and after surgery, and statistically analyzed. All patients were followed up for 6 to 23 months, with preoperative imaging studies, confirmed for thoracolumbar osteoporosis compression fractures, two groups of patients with postoperative complications, no special two groups of patients' age, gender, body mass index (BMI), time were injured, the injured vertebral distribution had no statistical difference(P>0.05), comparable data. Two groups of patients with bone cement injection, bone cement dispersion rate, preoperative and postoperative vertebral body height, protruding after spine angle(Cobb angle), VAS, ODI had no statistical difference(P>0.05). The operative time, intraoperative fluoroscopy times and anesthetic dosage were statistically different between the two groups(P<0.05). Compared with the traditional bilateral puncture group, the modified unilateral puncture group combined with 3D printing technology had shorter operation time, fewer intraoperative fluoroscopy times and less anesthetic dosage. The height of anterior vertebral edge, kyphosis angle (Cobb angle), VAS score and ODI of the affected vertebrae were statistically different between two groups at each time point after surgery(P<0.05). In the treatment of thoracolumbar osteoporotic compression fractures, 3D printing technology is used to improve unilateral puncture PVP, which is convenient and simple, less trauma, short operation time, fewer fluoroscopy times, satisfactory distribution of bone cement, vertebral height recovery and kyphotic Angle correction, and good functional improvement.

Using the Blackburne-Peel index to measure the patellar height on magnetic resonance images

To reveal the normal values of patellar height measurements using the Blackburne-Peel index on magnetic resonance (MR) images and to show the gender and age differences regarding this measurement technique. This retrospective cross-sectional study investigated 148 knee MR images, and those images were re-evaluated to find out the normal values of patellar height using the Blackburne-Peel index (BPI). An adapted measurement technique of this index was applied to MR images. The study group was analyzed regarding the sex and age differences, correlation with age was investigated, and all descriptive data were presented. Independent Samples T-test, Kruskal–Wallis variance analysis, and Spearman’s Rho correlation test was applied to calculate the results. The mean value was 0.80 ± 0.09 for the total of patients. The measurements regarding the height of the inferior edge of the patella articular surface and the length of the patella articular surface indicated a significant difference between females and males (p < 0.001 for both measurements). The descriptive data obtained from this study revealed the mean values of the whole study group, different sexes, and age groups separately. Additional studies are needed for adapting BPI on MR images and verifying the normal values of the population.

The combined research of ultra-high vacuum CF flange joints' sealing parameters considering plastic properties of materials

Computer simulation and experimental research of the tightening processes of ultrahigh vacuum CF flange joints have been carried out. Finite element analyses were carried out considering the plastic properties of materials. The analysis variable parameters are flanges' knife edge angle between the shelves (Wheeler's and CERN's models), tip rounding radiuses, and gasket material state (annealed and hard). Curves of changes in the stress and strain intensities of the edge nodes of the flanges' knife edge were obtained. Essential sealing parameters of the ultrahigh vacuum system were also studied, such as the height of the knife edge, the length of the knife-edge trace on the gasket (in the radial direction), and the gap between two flanges. The mentioned sealing parameters' measurements were carried out by the combined method. The latter is a parameters' measurement of both computer simulation and experimental samples and a comparison of the obtained results. It should be noted that the sealing parameters were studied for several tightening cycles of the flanges to research their changes in case of multiple uses. The vital value of this research is obtained empirical functions for calculating the height of the flanges' knife edge based on the tightening cycles.

Measurement of anatomical parameters of anterior transpedicular root screw intervertebral fusion system of cervical spine

ObjectiveThis study aims to investigate the feasibility of the anterior transpedicular root screw (ATPRS) intervertebral fusion system for the cervical spine and provide a basis for the design of the ATPRS intervertebral fusion system.MethodsA total of 60 healthy adult cervical spine CT images examined from our hospital were selected, including 30 males and 30 females, with an average age of 39.6 ± 4.8 years. The image data was imported into Mimics 21.0 software in DICOM format for 3D model reconstruction. Simulated screw insertion was performed on both sides of the midline of the intervertebral space. The entry point (P1) was determined when the upper and lower screw paths did not overlap. When the screw was tangent to the medial edge of the Luschka joint, the insertion point was determined as the entry point (P2). Measurements were taken and recorded for the following parameters: distance from the screw entry point to the midline of the intervertebral space (DPM), the simulated screw length, inclination angle, cranial/caudal tilted angle, the anterior–posterior (AP) and mediolateral (ML) diameters of the cervical intervertebral space, the heights of the anterior, middle, and posterior edges of the cervical intervertebral space, and the curvature diameter of the lower end plate of the cervical vertebral body. Statistical analysis was performed on the measurement results.ResultsThe screw entry area (P1P2) showed an increasing trend from C3-C7 in both male (2.92–6.08 mm) and female (2.32–5.12 mm) groups. There were statistical differences between men and women at the same level (P < 0.05). The average screw length of men and women was greater than 20 mm, and the upper and lower screw lengths showed an increasing trend from C3 to C7. In the area where screws could be inserted, the range of screw inclination was as follows: male group upper screw (47.73–66.76°), lower screw (48.05–65.35°); female group upper screw (49.15–65.66°) and lower screw (49.42–63.29°); The range of cranial/caudal tilted angle of the screw was as follows: male group upper screw (32.06–39.56°), lower screw (29.12–36.95°); female group upper screw (30.97–38.92°) and lower screw (27.29–37.20°). The anterior–posterior diameter and mediolateral diameter of the cervical intervertebral space showed an increasing trend from C3 to C7 in both male and female groups. The middle height (MH) of the cervical intervertebral space was greater than the anterior edge height (AH) and posterior edge height (PD), with statistical differences (P < 0.05). ConclusionsThrough the study of CT images of the cervical spine, it was determined that the ATPRS intervertebral fusion system has a feasible area for screw insertion in the cervical intervertebral space.

Reducing ion concentration polarization by optimizing reservoir size in membrane-based salinity gradient power generation systems

Salinity gradient power generation has attracted much attention for its green and sustainable advantages. However, previous studies have tended to overlook the effect of reservoir size in porous membrane systems on power generation (the reservoir size from nanometer to micrometer were applied for similar-sized nanochannels). In this work, we investigate the ion transport behavior and working performance in the salinity gradient power generation with different reservoir sizes. The results show that there is a significant dependence of reservoir length and edge height on the effect of salinity gradient power generation. Smaller reservoir length or larger edge height corresponds to weaker ion concentration polarization, larger effective concentration difference, and better power generation performance. The regulation of the energy conversion process by reservoir size is significant. The influence of reservoir size on salinity gradient power generation diminishes as the pore distance increases. Sufficiently large reservoir length and edge height are necessary if a more stable output power is to be obtained. This work illustrates the impact of reservoir size on power generation performance and its significant regulatory effect, providing useful information for future selection of reservoir size in porous membrane systems.

Analysis of edge jumps in multi-wavelength phasing of segmented-mirror telescopes.

Interferometric methods for phasing the primary mirrors of segmented-mirror telescopes generally need to make measurements at multiple wavelengths in order to achieve suitably large edge height capture ranges. In the presence of measurement errors, such methods have the potential for grossly wrong measurements, so-called edge jumps. In this paper, we investigate the causes of edge jumps using the example of Thirty Meter Telescope (TMT) phasing. We explain the reasons for their occurrence and develop a mathematical understanding of the conditions under which they arise. We describe how stability analyses of the vast parameter space relevant to TMT phasing can be accomplished in an efficient way and present examples of results. These concepts are also applicable to other multi-wavelength interferometric phase measurement techniques.

Effects of postural threat on perceptions of lower leg somatosensory stimuli during standing.

Height-induced postural threat affects emotional state and standing balance behaviour during static, voluntary, and dynamic tasks. Facing a threat to balance also affects sensory and cortical processes during balance tasks. As sensory and cognitive functions are crucial in forming perceptions of movement, balance-related changes during threatening conditions might be associated with changes in conscious perceptions. Therefore, the purpose of this study was to examine the changes and potential mechanisms underlying conscious perceptions of balance-relevant information during height-induced postural threat. A combination of three experimental procedures utilized height-induced postural threat to manipulate emotional state, balance behavior, and/or conscious perceptions of balance-related stimuli. Experiment 1 assessed conscious perception of foot position during stance. During continuous antero-posterior pseudorandom support surface rotations, perceived foot movement was larger while actual foot movement did not change in the High (3.2 m, at the edge) compared to Low (1.1 m, away from edge) height conditions. Experiment 2 and 3 assessed somatosensory perceptual thresholds during upright stance. Perceptual thresholds for ankle rotations were elevated while foot sole vibrations thresholds remained unchanged in the High compared to Low condition. This study furthers our understanding of the relationship between emotional state, sensory perception, and balance performance. While threat can influence the perceived amplitude of above threshold ankle rotations, there is a reduction in the sensitivity of an ankle rotation without any change to foot sole sensitivity. These results highlight the effect of postural threat on neurophysiological and cognitive components of balance control and provide insight into balance assessment and intervention.

A Clinical Comparative Study on Percutaneous and Open Approaches for Screw Internal Fixation in Treating Thoracolumbar Fractures.

Conventional open internal fixation surgery for thoracolumbar fractures has many complications and long recovery time. There are few clinical studies on the minimally invasive percutaneous injured vertebrae screw internal fixation. The purpose of this paper is to evaluate the application value of minimally invasive percutaneous injured vertebrae screw internal fixation in the treatment of thoracolumbar fractures (TF). A total of 98 patients with TF admitted to our hospital from January 2019 to December 2021 were retrospectively enrolled. According to the surgical method, the patients were divided into the study group (n = 49, treated with minimally invasive percutaneous injured vertebrae screw internal fixation) and the control group (n = 49, treated with traditional open internal fixation surgery). The two groups were compared in the perioperative period, the degree of pain at different periods, the percentage of the height of the anterior edge of the injured vertebra, the Cobb angle of the injured vertebra body and the wedge angle of the injured vertebra body at the first week and the last follow-up, and the postoperative complications and the occurrence of the cone shell after the operation were recorded. Then, statistical analysis such as Student's t test or Chi-Square test was performed. The operation time (p = 0.002), intraoperative blood loss (p < 0.001), postoperative drainage volume (p = 0.011), and length of hospital stay (p = 0.003) in the study group were significantly lower than that in the control group. The VAS in the study group (3.38 ± 1.02) was significantly lower than that in the control group (4.56 ± 1.04) on the 7th day after the operation, with a significant difference (p < 0.001). The correction values of the percentage of leading edge height (LEH), Cobb angle, wedge angle in the study group were significantly lower than that in the control group at 1 week after surgery (all ps < 0.001). The incidence of postoperative complications in the study group (one case, 2.04%) was significantly lower than that in the control group (seven cases, 14.29%) (p = 0.031). At 1 month, 6 months, 10 months, and the last follow-up, the incidence of "empty shell" on CT scan in the study group were lower than that in the control group with a significant difference (all ps < 0.05). Applying minimally invasive percutaneous injured vertebrae screw internal fixation is more beneficial to shorten the operation time and hospital stay, with fewer postoperative complications.

Relationship between lumbar disc herniation and Roussouly classification in the sagittal alignment of the spine and pelvis in young people.

The sagittal plane of spine-pelvis morphology of adult patients with lumbar disc herniation (LDH) differs from that of normal people. There is a correlation between abnormal sagittal plane morphology and adult LDH. This study aimed to investigate the relationship between LDH in young people and the Roussouly classification in the sagittal alignment of the spine and pelvis. A total of 126 patients with LDH hospitalized in our tertiary hospital between January 2020 and January 2021 who met the inclusion and exclusion criteria were retrospectively analyzed in a cross-sectional study. Participants were grouped according to the spinal level of disc herniation (L4/5 group, L5/S1 group, L3/4 group). Pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) of all cases were measured using standing lateral spinal radiographs. Facet joint angles (FJA) were measured using lumbar computed tomography (CT) horizontal radiographs, and the height of the anterior, middle, and posterior margins of the herniated disc was measured using sagittal radiographs. The classification of Pfirrmann disc degeneration was determined via magnetic resonance imaging (MRI) film of the lumbar region. Roussouly classification was performed according to sagittal plane morphology, and data were analyzed among each group. In all, 126 patients aged from 18 to 40 years, with an average age of 31.04±5.886 years were included. There were 63 cases of L4/5 disc herniation, 59 cases of L5/S1 herniation, and 4 cases of L3/4 herniation. There were 35 cases of epiphyseal separation. The Roussouly classification included 21 cases of type 1, 56 cases of type 2, 32 cases of type 3, 4 cases of type 4, and 13 cases of type 3 + anteverted pelvis (type 3-AP). The L4/5 disc herniation group had significantly more types 2 and 3 than the other groups, and the L5/S1 disc herniation group had significantly more types 1 and 2 than the other groups. There were no significant differences in the Pfirrmann grade of intervertebral disc degeneration; epiphyseal separation; the height of anterior, middle, and posterior margins of the herniated disc; the difference between left and right facet angle and bilateral facet angle; and the thoracic kyphosis (TK) value among any of the groups (P>0.05). There were significant differences in PI, PT, SS, lumbar lordosis (LL), and height of the anterior and posterior margins of the intervertebral space among all groups (P<0.05). PI values were grouped at 50°; PT, SS, and LL were significantly different (P<0.05), whereas TK values were not significantly different between the 2 groups (P>0.05). SS values were grouped at 35°, and there were significant differences in PI, TK, and LL between the 2 groups (P<0.05). According to the disc herniation segment, the patients were divided into L4/5 and L5/S1 groups. There were significant differences in PI, PT, anterior edge height, anterior to posterior edge height, left facet angle, right facet angle, and bilateral facet angle (P<0.05). LDH is common in L4/5 and L5/S1 segments. The incidence of Roussouly type 1 and 2 LDH is significantly higher than other types, and type 4 is the lowest. Small PI and small SS are more obvious in the L5/S1 segment. L5/S1 disc herniation is more common in patients with Roussouly type 1 and 2 classifications, whereas L4/5 disc herniation is more frequent in patients with Roussouly type 2 and 3 classifications.

Understanding Head Injury Risks During Car-to-Pedestrian Collisions Using Realistic Vehicle and Detailed Human Body Models.

Traumatic brain injury (TBI) is the leading cause of death and long-term disability in road traffic accidents (RTAs). Researchers have examined the effect of vehicle front shape and pedestrian body size on the risk of pedestrian head injury. On the other hand, the relationship between vehicle front shape parameters and pedestrian TBI risks involving a diverse population with varying body sizes has yet to be investigated. Thus, the purpose of this study was to comprehensively study the effect of vehicle front shape parameters and various pedestrian bodies ranging from 95th percentile male (AM95) to 6 years old (YO) child on the dynamic response of the head and the risk of TBIs during primary (vehicle) impact. At three different collision speeds (30, 40, and 50 km/h), a total of 36 car-to-pedestrian collisions (CPCs) were reconstructed using three different vehicle types (Subcompact passenger sedan, mid-sedan, and sports utility vehicle (SUV)) and four distinct THUMS pedestrian finite element (FE) models (AM50, AM95, AF05, and 6YO). We assessed skull stress and brain strains besides head linear and rotational kinematics. Our findings indicate that vehicle shape parameters especially bonnet leading edge height (BLEH), when being divided by the height of the Center of Gravity of the human body, correlated positively to head kinematics. The data from this study using realistic vehicle structures and detailed human body models showed that smaller BLEH/CG ratios reduced head injury criteria (HIC) and brain injury criteria (BrIC) values for the car center to mid-stance walking pedestrian impacts but with low-to-moderate R squared values between 0.2 to 0.5. Smaller BLEH/CG reduced head lateral bending velocities with R squared values of 0.57 to 0.63 for all impact velocities, and reduced HIC with R squared value of 0.62 for 50 km/h cases. In the future, simulations with realistic car structures and detailed human body models will be further used to simulate impacts at different locations and with various body shapes/postures.

Visualization and analysis of the impinging spray and combustion characteristics in a lateral swirl combustion system (LSCS)

A lateral swirl combustion system (LSCS) was proposed to improve the fuel/air mixing and combustion processes, and previous results have validated its excellent combustion performance in direct injection diesel engines. To further explore the fuel/air mixture mechanism of the LSCS, the effects of convex edge height ha = 2–8 mm (corresponding to interferential angle δ = 133°-14°) on the impinging spray and flame were investigated visually in a constant volume combustion system employing high-speed shadowgraph, direct photography and two-color methods. The experimental results suggested that the combustion chamber with ha = 6 mm (δ = 48°) exhibited superior results in terms of total spray area and combustion. Regardless of whether ha increased or decreased from 6 mm, all of which impaired the synthesis result of the wall-flow-guided and interferential effects. Specifically, when the ha was 2 mm, the wall-flow-guided effect was decreased, and the excessive δ corresponding to 133° caused the neighboring wall jets to approximate a head-on collision, which inevitably resulted in the part of fuel accumulation. Modified ha to 8 mm (δ = 14°), the neighboring wall jets developed nearly in the same direction, diminishing the interferential capacity. Similar higher-temperature and higher-soot areas were observed during the burn-out process for ha = 2 and 8 mm compared to what was obtained at ha = 6 mm, except that the bright area of ha = 2 mm was located near the convex edge at the bottom, while ha = 8 mm appeared in a higher position. Therefore, the LSCS, through exerting the comprehensive effects of wall-flow-guided and interferential interactions, obtains the optimal fuel/air mixing and combustion effects.

Experimental study on the effect of flare barriers on wave run-up and motion response of a semi-submersible platform

Semi-submersible platforms can suffer slamming damage from extreme waves, making it crucial to improve their airgap performance. To address this issue, this paper proposes an innovative flare barrier that can be attached to the surface of a column at a certain height above the waterline, drawing on bow flares used in ship design. This study conducts a series of experiments to investigate the effectiveness of the flare barrier in mitigating wave run-up and motion response of a semi-submersible platform. The experiment uses irregular waves with a 100-year return period, incident at angles of 180° and 135° to simulate the wave field. To reduce the transient effect, two different wave seeds are considered for each wave-heading condition. The results show that the flare barrier significantly mitigates wave run-up, especially at the height of the lowest edge of the barrier. The addition of flare barrier has no negative effect on surge, heave and pitch response. At incident angle of 180°, it even has a slight mitigation effect on heave and pitch. The mitigation effect is also demonstrated in the power spectral analysis. Considering the wave run-up and motion response, a flare barrier is recommended to mitigate wave run-up on the column and improve the airgap performance under extreme waves.

Wafer Eccentricity Deviation Measurement Method Based on Line-Scanning Chromatic Confocal 3D Profiler

The wafer eccentricity deviation caused by misalignment between the center of the wafer and rotary table will lead to edge image distortion and quality degradation of the defect signals during automated inspection. However, wafer end jump and edge topography change will bring great challenges to the accurate measurement of micrometer deviations. A new wafer eccentricity deviation measurement method based on line-scanning chromatic confocal sensors (LSCCSs) is proposed. Firstly, the LSCCS with Z-axis submicron resolution used in the experiment acquires the 3D profile height of the wafer edge as the turntable rotates, and the edge distance is calculated at each rotation angle. Secondly, a robust Fourier-LAR fitting method is used to fit edge distance serial to reduce sensitivity to outliers. Finally, the wafer eccentricity deviation that is equal to the wafer center coordinate can be calculated using the wafer eccentricity deviation model. In the simulated experiment, the results show that the eccentricity deviation measurement accuracy was insensitivity to noise and reached the micron level. Additionally, the measurement uncertainty of eccentricity deviation coordinate Xw,Yw was (0.53 µm, 1.4 µm) in the actual data of the 12-inch wafers.