Wall Height Research Articles

Morphometric Measurements of the Incomplete Partition Type II (IP-II) Cochlea and Implications on Cochlear Implantation.

The objective of this study is to obtain comprehensive morphometric measurements of the incomplete partition type II (IP-II) cochlea to provide a better understanding of intracochlear anatomy and important considerations for electrode selection and insertion. IP-II is the most common bony inner ear malformation that often requires cochlear implantation. Currently, there is significant controversy on electrode selection due to a lack of research that can provide reliable, high-resolution measurements. Three-dimensional reconstructions of the cochlea were made from hematoxylin and eosin-stained slides from 11 archival human temporal bones from 8 adult IP-II patients (one paired) and 2 fetuses. Detailed measurements of the angular and linear length of the spiral ganglion neurons and cochlear duct at the modiolar and lateral wall of the scala tympani as well as cross-sectional areas and vertical height measurements of the scala tympani at 90-degree intervals were measured. The spiral ganglia neurons terminated at 540.5 ± 45.4 degrees, which corresponded to the beginning of the interscalar septal defect. The corresponding Rosenthal's canal length was 12.75 ± 0.82 mm, and the lateral wall length was 23.95 ± 1.04. The average cochlear duct length was 32.44 mm ± 1.58 mm, corresponding to an average angular distance of 951.6 ± 80 degrees. The modiolar height demonstrated less variation within the scala tympani but was significantly smaller at 0 and 90 degrees compared with the normal cochlea. The lateral wall height was also significantly smaller at 0, 180, and 540 degrees. There was a drastic decrease in lateral wall height at 540 degrees to 0.4 mm, which is smaller than the apical dimension of many electrodes. This is the first study to provide detailed morphometric measurements of the IP-II cochlea including spiral ganglion neuron length and scala tympani height. These measurements directly relate to electrode selection for cochlear implantation.

Injuries from border wall falls after 2018 are more severe: a retrospective cohort study

BackgroundThe U.S.-Mexico “border wall” between El Paso, Texas and Ciudad Juárez, Mexico was raised and extended beginning in 2018 in accordance with Presidential Executive Order 13,767. We hypothesized that these changes resulted in increased incidence and severity of injuries of individuals attempting to cross the border wall in the El Paso region.MethodsA retrospective cohort review was conducted of University Medical Center of El Paso Trauma Registry charts from 2001 to 2022. Year of injury, gender, age, Injury Severity Score, hospital length-of-stay, ICU length-of-stay, ventilator days, and survival were analyzed by Chi-square analysis with Fisher’s exact test for categorical variables and Independent Samples T-test for continuous variables. An independent samples Mann Whitney U Test was used to compare border wall fall injuries before and after 2018.ResultsOf the 842 patients reviewed, 69 patients presented before 2018 and 773 presented from 2018 to 2022. Statistically significant differences were identified in the mean Injury Severity Score which increased from 6.3 (SD ± 3.8) to 8.3 (SD ± 5.5, p < .001) and the mean hospital length-of-stay which increased from 6.7 days (SD ± 5.5) to 9.5 days (SD ± 8.0, p < .005).ConclusionThe incidence, severity, and hospital length-of-stay related to injuries crossing the U.S.-Mexico border have increased with changes in height of the border wall since 2018. Additional resources should be allocated to Emergency Departments and Trauma Centers along the Southwest Border to serve this unique patient population. Additional consideration should be given to the cost of the border wall.

Hydraulic Modeling-Based Design of Retaining Wall Height for Flood Mitigation

Hydraulic Modeling-Based Design of Retaining Wall Height for Flood Mitigation

Experimental investigation on tailoring compressive properties and energy absorption of 3D printed gradient star re-entrant hybrid auxetic structure

Purpose Fused filament fabrication (FFF) is a widely used 3D printing technique for the fabrication of mechanical metamaterials with intricate geometries. Gradient strategy is applied to geometric parameters of gradient star re-entrant hybrid auxetic (GSRA) structure. Deformation behaviour is studied under compressive loading. The purpose of this study is to investigate the influence of gradient geometric parameters on mechanical properties, namely, specific strength (SS), specific modulus (SM) and specific energy absorption (SEA). Design/methodology/approach Response surface methodology (RSM) is implemented for the design of experiments of gradient geometric parameters to minimize the number of experimental tests. Acrylonitrile butadiene styrene material is used for the fabrication of GSRA structures by FFF technique. The best set of gradient parameters has been optimized maximizing all three responses using RSM and artificial neural network optimization technique. Findings During compressive testing, row-wise deformation is observed with two-stage plateau regions, which results in increase in SEA of the structure. Furthermore, based on analysis of variance and 3D response plots, it is found that height gradient is the most influencing gradient geometric parameter on SS and SM, whereas the wall thickness gradient has maximum influence on SEA. Meanwhile, the interaction effect of wall thickness gradient and height gradient has maximum influence on SS, SM and SEA. Research limitations/implications This study of applying gradient strategy to geometric parameters is limited to GSRA structure under compressive loading. In addition, findings are valid within the selected range of gradient geometric parameters. These findings are useful for the selection of gradient geometric parameters to maximize SS, SM and SEA of GSRA structure simultaneously. These outcomes pave the way for designing light-weight gradient hybrid auxetic structures in the field of construction, aerospace, automobile and biomedical engineering. Originality/value Limited experimental study is available on investigating the influence of gradient geometric parameters on mechanical properties, namely, SS, SM and SEA, and deformation behaviours of hybrid auxetic structures. This study directly addresses the above research gaps.

Coal‐wall spalling prevention mechanism using advance‐grooving pressure relief in the large‐mining‐height working face of a shallow coal seam

AbstractIn mining, the roof structure of a working face with a large mining height in a shallow‐buried coal seam is prone to cutting instability in front of the support, which causes support crushing and coal‐wall spalling. This study analyzes 2201 working faces with large mining heights in the Haiwan No. 3 Mine by investigating the mechanical response law of coal walls under the transient excitation of roof structure instability. A mechanical model of coal walls under dynamic and static load coupling is established, revealing the formation mechanism of coal wall spalling and its main influencing factors. Prevention and control technologies of advanced grooving and pressure relief are proposed, and grooving parameters are determined. The results show that: During the mining process of large mining height working face in shallow buried coal seam, the step change of static response of coal wall is induced by the transient instability of roof structure, and the high abutment pressure is formed on the coal wall. At the same time, the strain energy and gravitational potential energy of roof cutting instability are released to form a dynamic load. Under the action of dynamic and static load, the plastic failure dissipation power of the coal wall is greater than the critical power, and the coal wall spalling occurs. The main influencing factors are mining load, mining height, and internal friction angle of the coal wall. The method of advanced grooving pressure relief can change the roof structure and coal force mechanism, by cutting off the connection between the coal wall and immediate roof, reducing the height of the coal wall force, effectively controlling the position of the roof cut off break line, reducing the static load effect of the roof on the coal, and transferring the position of the dynamic load response to the depth of the coal wall. When the grooving height‐depth ratio k is 0.75, the peak value of the abutment pressure moves 5.57 m to the front of the working face, and the pressure relief effect is the best. The above research results provide an effective active protection method for controlling coal wall spalling in fully mechanised working face with large mining height.

Wall Shading Losses of Photovoltaic Systems

The deployment of photovoltaic (PV) systems on rooftops in urban environments may encounter shading on the PV collectors from surrounding walls, acting adversely on the generated electricity of the PV systems. Most studies on the shading of PV systems do not deal analytically with the shading losses of PV collectors affected by walls, fences, and obscuring objects. The present article mathematically formulates shadow expressions for wall and inter-row shading on PV collectors and calculates the percentage of annual shading losses affected by wall heights and azimuth angles, the distances of walls to collectors, and the length and azimuth angles of collectors. This study indicates that the shading losses increase for shorter distances from the collector to the walls and for higher walls. Shading losses may reach 7 percent for wall heights of 4 m and at a distance of 2 m from the collectors to a wall. The results indicate that wall shading dominates inter-row shading.

In-plane crushing behavior and energy absorption of CFRP honeycombs with different core topologies

The in-plane crushing behavior and energy absorption performance of carbon fiber reinforced polymer (CFRP) honeycombs with different core topologies were experimentally investigated under uniaxial loading conditions. Three types of CFRP honeycomb core topologies (i.e. circular, square and hexagonal) with different cell wall thicknesses and heights were considered in the designs. The honeycomb samples were fabricated by the molding and bonding process, which is widely used in the easy, fast and economical manufacturing of thin-walled honeycomb structures. A total of twenty-seven sample groups were experimentally tested for each loading condition, in which honeycomb samples with different core topologies were designed to have almost the same weights for a meaningful comparison. The experimental results revealed that all honeycomb designs have higher in-plane compression strength in the expansion direction, and hexagonal honeycombs showed the highest strength and energy absorption performance in both directions due to their stable load-carrying capacity and outstanding force efficiency. In particular, the experimental findings showed that the crushing strength and the specific energy absorption of CFRP honeycomb structures can be improved up to 6.1 and 4.2 times, respectively, by properly adjusting the cell wall thickness and height parameters. The results also revealed that the proposed lightweight CFRP honeycombs with the structural densities of 155–283 kg/m3 showed better in-plane crushing performance than many competing cellular topologies.

Analysis of the interactions between laser and arc due to different geometric arrangements and laser parameters in the additive manufacturing of Ti-6Al-4V

Additive manufacturing based on arc welding (=DED-Arc) has already established itself in the world of additive manufacturing. Recent process optimizations show the increased use in a hybrid process by irradiating an additional laser beam into the active arc zone. Numerous publications can be found in the literature for steel, aluminum, or bronze, in which, among other things, a strength-enhancing effect or an improved wall surface during this hybrid process is reported. The way in which the laser beam impacts the arc, at what distance, at what angle and with what spot size or focusing appears to be random in the publications and is always chosen differently in the literature. In order to close this knowledge gap, a corresponding holder for a DED-Arc torch and laser optic is developed, which allows these geometric factors to be systematically changed and also enables the titanium alloy Ti-6Al-4V to be processed in a hybrid process. By welding individual tracks and walls with different angles, distances and spot sizes of the two energy sources, a fundamental understanding of the laser-arc hybrid process is created. The results are analyzed using a high-speed camera and evaluated on the basis of surface measurements, micrographs, and power source values. This showed that the distance between the laser and the arc has the greatest effect on the additive process stability and the arc power sources values. In the range of 2–6 mm, there are, in some cases, strong fluctuations in the wire deposition and the arc voltage, so that this range should be avoided. It also showed that a wider spot sizes range of 360–600 μm can be used, whereby different ranges are recommended depending on the target size of uniform wall height or thickness. For the laser incidence angle, the most uniform walls across all tests are achieved at 20°. As the angle of incidence becomes flatter, the walls become more irregular, although there is no linear relationship or areas that should be avoided at all.

Percutaneous kyphoplasty combined with pediculoplasty (PKCPP) augments and internally fixates the severe osteoporotic vertebral fractures: a retrospective comparative study.

Vertebral augmentation (VA) has emerged as a satisfactory and minimally invasive surgical approach for severe osteoporotic vertebral fractures (OVFs). However, treating severe OVFs with advanced collapse, burst morphology with MC injury, posterior wall retropulsion, high degree of osseous fragmentation, pediculo-somatic junction fracture, and large vacuum cleft presents significant challenges. This study aimed to evaluate the effectiveness of percutaneous kyphoplasty combined with pediculoplasty (PKCPP) in reducing refracture, preventing further collapse and bone cement displacement, reconstructing vertebral body (VB) stability, and providing internal fixation of the anterior column (AC), middle column (MC), and the bilateral pedicles. The current study was designed as a retrospective review of clinical and radiologic parameters. From July 2018 to September 2021, ninety-six patients with severe OVFs and without neurological deficit were treated either with simple percutaneous kyphoplasty (simple PKP group, n = 54) or with percutaneous kyphoplasty combined with pediculoplasty (PKCPP group, n = 42). All patients were followed up for at least 1year, and clinical and radiological outcomes were assessed. Surgery duration and bone cement volume were compared between the two groups, as well as analgesic dosage and hospital stay. Anterior wall height (AWH), posterior wall height (PWH), and Cobb angle (CA) were measured and analyzed before and after surgery. The simple PKP group had significantly shorter surgery duration and lower bone cement volume compared to the PKCPP group (P < 0.05). Conversely, the simple PKP group had significantly higher analgesic dosage and longer hospital stay than the PKCPP group (P < 0.05). Both groups showed significant improvements in AWH, PWH, and CA after surgery (P < 0.05). At the final follow-up, the PWH in the simple PKP group was significantly lower than the preoperative measurement (P < 0.05), and the difference in PWH between the two groups was statistically significant (P > 0.05). Moreover, both groups demonstrated a significant reduction in CA after surgery, with the PKCPP group showing a greater reduction compared to the simple PKP group throughout the postoperative period to the final follow-up (P < 0.05). VAS and ODI scores significantly decreased in both groups after surgery (P < 0.05), with no significant difference between the groups at the final follow-up (P > 0.05). However, the PKCPP group achieved better VAS scores than the simple PKP group at postoperative 1day, 1month, and 3months (P < 0.05), and the ODI in the PKCPP group was lower than the simple PKP group at 1month after surgery (P < 0.05). Furthermore, the overall complication rate in the PKCPP group was significantly lower than that in the simple PKP group (P < 0.05). If performed by appropriately trained surgeons, both PKP and PKCPP are safe and effective treatments for patients with severe OVFs. However, PKCPP offers additional benefits in the setting of bothersome fractures, including rapid pain relief, improved spinal stability, satisfactory restoration of vertebral body height, and better correction of kyphotic deformity. These promising results have been tested in a single center but require further confirmation in multiple centers.

Improving the shape and dimensional accuracy of hollow semi-finished products during hot reverse extrusion from square workpieces

Stamping of round hollow semi-finished products by hot reverse extrusion from round and square workpieces is the first stamping step in the manufacture of hollow products for special purposes. These products require certain mechanical properties along the wall height and in the bottom part, which can be achieved by working out the metal structure by plastic deformation. The bottom part is worked out by reverse extrusion. The wall properties are obtained in the following stages of drawing the semi-finished product with thinning after extrusion. The use of square workpieces results in more intensive working out of the bottom of the semi-finished products during the reverse extrusion. However, as a result of extrusion, four protrusions appear at the end of the semi-finished product wall in places that match the corner areas of the workpiece. The presence of protrusions leads to the need for an additional operation of cutting the end of the semi-finished product before extrusion, as well as to an increase in metal usage. Therefore, an urgent task is to study the method of eliminating protrusions in the semi-finished product and the additional cutting operation.To improve the accuracy of the shape and size of hollow semi-finished products during hot reverse extrusion from square workpieces.Elimination of protrusions is achieved by forming chamfers in the corner zones of the square workpiece by preliminary deposition before extrusion.The finite element method (FEM) was used to model the processes of hot deposition of corner zones on a square workpiece and subsequent reverse extrusion with the dispensing of round hollow semi-finished products. The dimensions of the chamfers on the high-carbon steel workpiece were determined, which ensured the elimination of protrusions at the end of the wall of the round semi-finished product after extrusion. The dependence of the deposition and extrusion forces on the punch movement was determined. The specific forces on the deforming tool were determined. The distributions of stresses, strains, and temperature in the deformed metal at the end of deposition and extrusion are presented. The working out of the metal structure by hot plastic deformation is evaluated. The design of a stamp for deposition and extrusion is developed.The geometry of a square workpiece with chamfers in the corner zones was determined, which ensures the elimination of protrusions at the wall end during hot reverse extrusion with the dispensing of round hollow semi-finished products

Stability design of multi-celled corrugated-plate CFST walls under combined axial and in-plane bending loads

Multi-celled corrugated-plate concrete-filled steel tubular (MC-CFST) walls are innovative steel-concrete composite walls comprising horizontally arranged corrugated steel plates, interval flat steel plates, and infilled concrete. Due to the significantly improved out-of-plane stiffness, the corrugated steel plate provides a considerable confinement effect on the infilled concrete, which enhances the structural efficiency and cost-effectiveness of MC-CFST walls. In this study, the stability performance of MC-CFST walls under combined axial and in-plane bending loads was investigated through extensive numerical simulations. A refined finite element (FE) model was established and validated using existing test results. Moreover, a formula for calculating the bending capacity of MC-CFST walls was also derived and validated against FE results. Additionally, parametric analyses were conducted to evaluate the effects of various factors such as the wall width, wall height, concrete strength, steel strength, and width of individual corrugated cells on the global stability performance. It was found that the stability performance was predominantly affected by the overall width of the wall rather than the width of the individual corrugated cells, with an increase in wall dimensions generally diminishing the stability performance. Furthermore, increasing the concrete strength improved the stability performance, while increasing the steel strength had a negative effect. Finally, a design formula was proposed for evaluating the bearing capacity and stability performance of MC-CFST walls under combined axial and in-plane bending loads. The formula demonstrated good agreement with the FE results, and it could provide a valuable reference for practical designs of MC-CFST walls.

Out-of-plane behavior of unreinforced masonry walls with horizontal slip layers in RC frames

In some cases, the infilled walls may be subjected to in-plane（IP） earthquake and out-of-plane(OOP) earthquake action due to the uncertainty of earthquake action and infills’ position. As a new type of unreinforced masonry(URM) walls with horizontal slip layers, it can effectively reduce the in-plane damage of infilled walls of reinforced concrete frames under an earthquake. However，the infill wall out-of-plane damage has a greater security threat than in-plane damage. In this study, a numerical study about the difference of OOP behavior of URM walls with/without horizontal sliding layers are analyzed, mainly including failure mode, bearing capacity, displacement capacity and stiffness. The spacing of horizontal slip layers, length of annectent reinforcing bars and the friction efficient between slip layer and masonry unit are chosen to investigate the differences of OOP mechanical behaviors. The results show that the horizontal sliding layers reduce the integrity of URM walls in reinforced concrete frames, causing the constraint of surrounding frame on infilled wall and the arching effect inside infilled wall become weaker, and OOP bearing capacity to drop. It is found that i) the annectent reinforcing bars is conducive to reducing the out-of-plane failure of the wall; 2)the smaller the slip layer spacing of the wall is, the more serious the damage of the infill wall under the out-of-plane load is, and the smaller the out-of-plane bearing capacity and the out-of-plane stiffness of the wall are; iii) the influence of the friction coefficient between slip layers and masonry unit on OOP mechanical behaviors is small. Finally, Chinese building design code is also selected to estimate the OOP bearing capacity of URM walls with horizontal sliding layers. The value of λcr is recommended to be greater than 1.0, and the value of λP is greater than 3.3. The spacing of the slip layer should be greater than 1 / 5 of the wall height, and the length of the annectent reinforcing bars should not be less than 1 / 5 of the infilled wall length.

Aerodynamic Optimization Design of a Supergravity Centrifuge: A Low-Resistance Strategy

Wind resistance optimization is crucial for enhancing the rotational speed of supergravity centrifuges. We conducted a study using computational fluid dynamics on the Centrifugal Hypergravity and Interdisciplinary Experiment Facility (CHIEF) under construction at Zhejiang University and validated it experimentally using a ZJU400gt centrifuge. Our findings indicate significant reductions in wind resistance through structural modifications of the CHIEF. Reducing the outer radius from 4650 to 4150 mm decreased wind resistance by 16%, primarily due to reduced effective viscosity in the wake region’s gases. More substantial reductions were achieved by lowering the height of the outer wall from 2200 to 1400 mm, which cut wind resistance by 25%. This height reduction suppressed vortex shedding and Kármán vortex street development via the Venturi effect. Adjustments to the roughness height of wall surfaces further decreased wind resistance, with minimal impact from arm roughness. A critical roughness height was identified, below which no further reductions in wind resistance could be attained. Notably, using disc-shaped arms reduced wind resistance by approximately 73% because of their minimal pressure–resistance components and predominant frictional resistance, highlighting their potential in future high-speed centrifuge designs.

Calculation method for static and seismic active earth pressure on counterweight retaining walls under translation based on two critical slip surfaces

The counterweight retaining wall with polyline wall back is a kind of gravity walls, which can be alternatively used in high embankments. To completely analyze active earth pressure on the polyline back under the wall translation mode, a comprehensive method is proposed based on two planar slip surfaces in the retained soil, an inclined slice method within the frame of limit equilibrium, and the pseudo-static approach. Meanwhile, the two critical slip surfaces include the global and local ones in the soils behind the whole wall and only the upper wall, respectively; and mobilized shear strength coefficients on interslice surfaces are introduced to fully consider the interslice shear forces. Some examples show that the proposed resultant forces on the whole wall are close to the experimental and numerical results generally within 10% error. The dip angle of backfill surface has a significant effect on the two slip surfaces, and the inclination of the lower back mostly influences the global slip surface. The unloading effect of the platform on the lower earth pressure becomes obvious as the upper wall lengthens under a constant height of the whole wall. The magnitude and profile of the seismic earth pressure on the polyline back are greatly influenced by the seismic coefficients.

Evaluation of colour change, marginal adaptation, fracture strength, and failure type in maxillary and mandibular premolar zirconia endo-crowns

ObjectivesThe objective of this in vitro study was to evaluate the effects of different preparation designs on the mean colour change (ΔE*), marginal adaptation, fracture resistance, and fracture types of maxillary and mandibular premolar endocrowns (ECs).MethodologyA total of 40 extracted maxillary and mandibular premolars were treated endodontically, and each type was subdivided according to the remaining axial height (remaining walls on all surfaces; 2–4 mm) and 2 mm inside the pulp chamber. Specimens were immersed in coffee for 14 days, ΔE* was determined, marginal adaptation was observed, fracture forces test was conducted, and the samples were examined visually at 10× magnification to evaluate failure type and identify fracture origin. The data were entered and analyzed using Statistical Package for Social Sciences, and significance between and within groups was evaluated through ANOVA. The p-value ≤ 0.05 was considered statistically significant.ResultsThe ΔE* values of the maxillary premolar with 2 mm axial height were the highest (6.8 ± 0.89 units), whereas the lowest value was observed in the mandibular premolar with 4 mm axial height (2.9 ± 0.53 units). Significant differences (p < 0.05) in teeth and design were observed. The marginal adaptation of the mandibular premolar with 4 mm axial height was the highest (30.20 ± 1.53 μm), whereas the lowest marginal adaptation was observed in the maxillary premolar with 2 mm axial height (14.38 ± 0.99 μm), and the difference was statistically significant (p < 0.05). The maximum fracture force was observed in maxillary premolars with 2 mm axial height (2248.15 ± 134.74 N), and no statistically significant difference (p = 0.07) was observed between maxillary and mandibular premolars at 4 mm axial height.ConclusionThe recorded ΔE* values of the ECs were within clinically acceptable values or slightly higher, and the marginal adaption values were within acceptable and recommended clinical values in µm. EC preparation with 2 mm axial height in both arches recorded the highest fracture forces. Type III (split fracture) failure was recorded as the highest in the maxillary and mandibular premolar ECs with different axial wall heights.

Estimating merchantable and non-merchantable wood volume in slash walls using terrestrial and airborne LiDAR

Slash walls are an effective forest management practice to prevent deer herbivory and promote forest regeneration following a timber harvest. However, the material cost, i.e. amount of wood material, needed for quality slash walls is unknown or at best based on highly uncertain empirical estimation. Quantifying how total and merchantable timber wood volume varies with width and height across slash walls will facilitate future planning and application of slash walls. In this study, we estimated wood volume per unit length (∼30.48 m) from total stem cross-sectional area in 40 randomly selected cut-through passages cut into 14 slash walls located at Cornell University’s Arnot Teaching and Research Forest (ATRF) in south-central New York. Within each passage we used Terrestrial Laser Scanning (TLS) to identify individual stems and obtain cross-sectional surface area. We found that TLS derived stem diameters were highly consistent with manual stem diameter measurements for 10 selected wall passages (N = 308, R2 = 0.933, RMSE = 1.881 cm). However, TLS tends to underestimate total cross-sectional area due to omission of small stem cross-sections (diameter < 5.08 cm). Cross-sections of small stems often have a low number of total points even when point density is high, especially when they are not facing the scanner. They are also more vulnerable to occlusion (i.e., lack of points due to blocking by other stems). TLS-based wood volume estimates were similar across both short and tall slash walls in the study with an average volume of 21.34 m3/30 m for short slash walls and 21.50 m3/30 m for tall slash walls, corresponding to 16.9 t dry biomass /30 m and 17.0 t dry biomass /30 m respectively. The small difference in woody volume was due to tall slash walls achieving additional height mainly through non-compacted small diameter crown and brush tops that have little woody volume. Average merchantable (diameter > 15.24 cm) and non-merchantable (diameter < 15.24 cm) timber fraction was 68.75 % and 31.35 % for short slash walls and 65.04 % and 34.96 % for tall slash walls. We further assessed slash wall height and width using Airborne Laser Scanning (ALS) for eight other tall slash walls. We found TLS measurements are representative of whole slash wall height and width variability based on ALS measurements. Our results provide novel data and methodology to estimate the construction cost of slash walls which are critical for optimizing slash wall applications.

Assessing Delayed Collapse Risks in Load-Bearing Reinforced Concrete Walls Exposed to Parametric Fires: A Numerical Investigation

This study delves into the thermo-mechanical analysis of structures exposed to fire, focusing on the evolution of gas temperatures, thermal distribution in structural members, and mechanical behavior during fire scenarios. Traditional prescriptive approaches assume a monotonically increasing temperature, while contemporary performance-based designs incorporate both heating and cooling phases for a more realistic fire resistance assessment. The critical aspect of this research is the modeling of the fire's cooling phase, which, though not commonly practiced in design offices, is essential for evaluating the risk of delayed structural collapse. Utilizing the finite element program SAFIR, numerical simulations were conducted on reinforced concrete walls to investigate their behavior during and post-cooling phase. The findings indicate potential failure not only during the cooling phase but also after the fire has subsided and temperatures have returned to ambient levels. This highlights delayed temperature increases in the core of the element and the consequent loss of concrete strength during cooling as key mechanisms of failure. A parametric study was undertaken, examining various fire scenarios, wall geometries, load levels, wall heights, adjacency, and boundary conditions. The results underscore that short-duration fires pose the most significant risk for delayed failure, particularly for simply supported walls. Additionally, the study scrutinizes the mechanical properties of materials across the heating and cooling phases. This investigation underscores the necessity of incorporating cooling phase analyses in fire resistance evaluations to mitigate the risk of delayed collapses. The insights gained aim to inform safer structural designs and enhance fire safety protocols, emphasizing the importance of realistic fire modeling in performance-based design methodologies.

Seismic response of column‐supported silos considering granular–structure interaction

AbstractTo predict the seismic response of column‐supported silos (CSSs), the granular–structure interaction (GSI) analysis method is proposed with considering the combined effect of the friction between the particles–particles and the particles–silo wall. Using free‐body dynamic equilibrium equations, we reconstruct the mutual interactions between different grain portions and between the grains and the silo wall to develop the ideal calculation model of the CSS structure. Based on the analysis model, additional dynamic overpressure and the effective mass caused by the stored content interacting with the silo wall is obtained with different slenderness ratios and peak accelerations. The additional bending moment caused by the friction between the particles and silo wall is further quantified. To verify the reliability of the proposed method, we discuss some applicative examples by comparing the GSI method with other theories, Eurocode 8, and experimental results. Moreover, the along‐the‐height acceleration profiles of the silo wall and the ensiled content are analyzed according to the shaking‐table tests. The results show that the GSI method can match Janssen's theory well in the case of static pressure at slenderness ratios exceeding 1.0. The overpressure profiles along the height of the silo wall follow a nonlinear distribution, different from Eurocode 8. The bending moment obtained by predictive formulas agrees well with the experimental results for the CSS, indicating that the GSI method is reasonable. Some design and construction recommendations, including the maximum overpressure position, the reference range of the dynamic overpressure coefficient, and the reduction factors of the ensiled content mass, are proposed to facilitate the engineering applications of CSSs, considering different slenderness ratios.

Morphometric analysis of atlas lateral mass in Down syndrome cases with relevance to surgical intervention.

Surgical stabilization of the Atlas vertebrae is indicated for severe atlantoaxial instability (AAI) in patients with Down syndrome (DS). This study aims to evaluate the morphological characteristics of the Atlas lateral mass (ALM) in patients with DS with regard to safe instrumentation for surgical stabilization and to compare them with non-syndromic group. This multicenter, retrospective, case-control study included age- and sex-matched patients with and without DS aged > 7 years with a cervical computed tomography (CT) scan. After three-dimensional CT reconstruction, nine parameters were evaluated for both groups. All included measurements were performed by a neuroradiologist who was blinded to clinical data. Forty-three of 3,275 patients with DS were included in this study. Matching number of consecutive patients without DS were identified (mean age: 16 years). Patients with DS were significantly shorter than those without DS. Seven of nine parameters related to ALM were significantly lower in patients with DS than in those in the control group, including anterior wall height (AH), posterior wall height (PH), their ratio, and arch-ALM angle. On adjusting data for patient height, patients with DS had a smaller PH, lower PH/AH ratio, and steeper arch-ALM angle than the control group. Patients with DS had a smaller posterior ALM wall and a steeper arch-ALM angle than the control group without DS. This information is important for surgical planning of safe posterior ALM exposure and safe instrumentation for surgical stabilization in patients with DS.

Study on the detectability of CSRMT in archaeological exploration: taking the ancient city wall remains as an example

Although electromagnetic methods have made significant advances in archaeological exploration, there remains a lack of a method that offers both high operating efficiency and high resolution. This study introduces a novel approach derived from the Controlled Source Radio Magnetotelluric (CSRMT) method. The CSRMT method combines the efficient configuration of the Controlled Source Audio-magnetotelluric (CSAMT) method with enhanced resolution capabilities. To evaluate the efficacy of the new method in archeological exploration, we designed a series of models based on existing references related to ancient city wall remains. Using the 3D contraction integral equation method, we numerically simulated the high-frequency component of the CSRMT method, and then on, the Laterally Constrained Inversion technique is used to invert the data. The effectiveness of the method was assessed qualitatively and quantitatively through analysing the electromagnetic field and apparent resistivity of models with varying widths, heights, top burial depths, and resistivity. Our analysis revealed that models with shallower burial depth and greater height of the underground city wall exhibited higher resolution. The findings demonstrate that the CSRMT method can efficiently and accurately identify buried remains, making it a highly promising tool for archaeological exploration and warranting further development.