Wedge Type Research Articles

Experimental and numerical investigation of the load-bearing capacity of bolt-fastened wedge active joints for prestressed internal bracing in subway excavations

The present study develops a novel type of active joint node-bolt fasten wedge (BFW) active joints, aiming to investigate the load-bearing capacity of a BFW joint in a quantitative way and put forward precise formulas for its yield load and compression rigidity. To achieve this, indoor axial loading tests were conducted on two BFW joints, accompanied by a set of numerical simulations with the finite element approach (FEA) implemented in ABAQUS. Parametric research was then conducted to assess the impact of various factors on the yield load and initial compression rigidity of BFW joints, leading to the derivation of precise calculation formulas for accurate prediction of these parameters. The key findings indicate that enhancing the bolt strength from 10.9 to 12.9 significantly improves mechanical performance. Under axial compression, the final bearing force, yield load, and initial compression rigidity increase by 0.86, 1.06, and 0.15 times, respectively. Numerical models accurately predict joint behavior under axial force, confirming their reliability. Parameter studies reveal that increasing web and eaves thickness, bolt strength, and diameter improves bearing capacity, while splint thickness has little effect. The fitting formulas introduced can precisely estimate yield load and rigidity, providing practical value for engineering applications.

Optimizing thermal efficiency: Advancements in flat plate heat exchanger performance through baffle integration

Compact heat exchangers have been gaining popularity in many industrial applications. Various types of passive turbulising structures such as corrugations, protrusions and ribs are introduced in the flow path to increase the effective heat transfer area and the level of turbulence in the flow path. This study investigates the impact of introduction of baffles on the performance of PHEs in terms of flow characteristics, pressure drop, and heat transfer. Two distinct types of baffle structures, namely wedge and aerofoil configurations, were introduced at varying numbers - 1, 3, and 5. An extensive experimentation is conducted for a FPHE in a thermal power plant of 500 × 2 MW and various flow and thermal parameters are measured. Computational Fluid Dynamics is utilized in this study to find the optimum baffle configuration. A detailed validation study is executed to obtain the correct computational algorithm, that is the right mesh count, optimum turbulence model, and precise numerical algorithm by comparing the numerical results with the available experimental results. Wedge- type baffles create increased turbulence and pressure drop, while aerofoil-type baffles minimize stagnation and exhibit lower pressure drop. Both baffle configurations lead to a substantial increase in heat transfer, with the 5-wedge-baffle setup showing the highest up to a 55% enhancement of Nusselt number. The Performance Evaluation Criterion (PEC) of wedge and aerofoil type is about 1.24 to 1.3 and 1.22 to 1.24 to that of conventional one respectively.

The impact of wedge and wavy-wall combustor side walls on shock-induced mixing and combustion in a hydrogen-fuelled model scramjet combustor

The mixing and combustion processes are linked and challenging for a supersonic combustion engine. Supersonic air doesn't spend much time in the combustor, making it challenging to blend fuel with supersonic air. The expansion of shear-mixing layer with shock waves and their interactions are the primary characteristics of mixing augmentation. This paper investigates the same methodology for a model scramjet combustion chamber with wedge and wavy sides. The novel scramjet combustion models include wedge and way-wall sidewalls based on the basic scramjet model. By combining the finite volume approach with a second-order upwind discretization method, the Reynolds-averaged Navier-Stokes equations are numerically analyzed. The interplay between wedge and wavy-wall effects and free stream flows is taken into consideration by using the shear stress transport (SST) k−ω turbulence model. The effect of the wedge and wavy wall combustor has been evaluated by analysing the shock production and their interactions with the mixing layer and internal flow structure. The turbulence characteristics are also examined to analyse the degree of flow disturbance for wedge and wavy-wall combustion. The wavy wall combustor model results in a 14.5% increase in turbulence intensity, which raises air-fuel mixing and there by improves mixing and combustion efficiency by 12.59% and 11.23%, compared to the base wedge type combustor.

Impact of Local Tailoring on Acute Stroke Care in 21 Disparate Emergency Departments: A Prospective Stepped Wedge Type III Hybrid Effectiveness-Implementation Study.

Faster delivery of tPA (tissue-type plasminogen activator) results in better health outcomes for eligible patients with stroke. Standardization of stroke protocols in emergency departments (EDs) has been difficult, especially in nonstroke centers. We measured the effectiveness of a centrally led implementation strategy with local site tailoring to sustain adherence to an acute stroke protocol to improve door-to-needle (DTN) times across disparate EDs in a multihospital health system. Prospective, type III hybrid effectiveness-implementation cohort study measuring performance at 21 EDs in Utah and Idaho (stroke centers [4]/nonstroke centers [17]) from January 2018 to February 2020 using a nonrandomized stepped-wedge design, monthly repeated site measures and multilevel hierarchical modeling. Each site received the implementation strategies in 1 of 6 steps providing control and intervention data. Co-primary outcomes were percentage of DTN times ≤60 minutes and median DTN time. Secondary outcomes included percentage of door-to-activation of neurological consult times ≤10 minutes and clinical effectiveness outcomes. Results were stratified between stroke and nonstroke centers. A total of 855 474 ED patient encounters occurred with 5325 code stroke activations (median age, 69 [IQR, 56-79] years; 51.8% female patients]. Percentage of door-to-activation times ≤10 minutes increased from 47.5% to 59.9% (adjusted odds ratio, 1.93 [95% CI, 1.40-2.67]). A total of 615 patients received tPA of ≤3 hours from symptom onset (median age, 71 [IQR, 58-80] years; 49.6% female patients). The percentage of DTN times ≤60 minutes increased from 72.5% to 86.1% (adjusted odds ratio, 3.38, [95% CI, 1.47-7.78]; stroke centers (77.4%-90.0%); nonstroke centers [59.3%-72.1%]). Median DTN time declined from 46 to 38 minutes (adjusted median difference, -9.68 [95% CI, -17.17 to -2.20]; stroke centers [41-35 minutes]; nonstroke centers [55-52 minutes]). No differences were observed in clinical effectiveness outcomes. A centrally led implementation strategy with local site tailoring led to faster delivery of tPA across disparate EDs in a multihospital system with no change in clinical effectiveness outcomes including rates of complication. Disparities in performance persisted between stroke and nonstroke centers.

Effect of Different Flame Deflectors Plate Geometry on Supersonic Jet Impingement Flow and Heat Characteristics from Rocket Exhaust

The numerical investigation has been carried out on an under-expanded supersonic jet impingement on the perpendicular and inclined deflector plates of various shapes, such as flat, sinusoidal, and wedge types. The numerical study considers flat plates at Mach number of 2.2, and pressure ratio of 1.2, and results of flow and heat transfers are obtained using the Reynolds averaged Naiver Stokes (RANS) two-equation turbulence models. Various two-equation models (especially Standard k-ε, Reynolds Normalization Group k-ε, Realizable k-ε, Shear Stress Transport k-ω, and Baseline k-ω) were employed to predict the deflector’s surface temperature and pressure ratios. The pressure ratios are plotted with various two-equation turbulence models, and it is observed that among all turbulence models, the Shear Stress Transport k-ω shows close agreement with experimental results. Moreover, among the three deflectors, the wedge-shaped deflector shows improved performance in deflecting the rocket exhaust plume away from the surface. However, the maximum temperature on the deflector surface for a wedge-shaped deflector is 8.19% and 26% higher than the flat and sinusoidal-shaped deflectors, respectively.

Anterolateral Dual Plate Fixation for Distal Metaphyseal-Diaphyseal Junction Fractures of the Humerus: Biomechanical Finite Element Analysis with Clinical Results.

Distal metaphyseal-diaphyseal junction fractures of the humerus are a subset of injuries between humeral shaft fractures and distal intra-articular humerus fractures. A lack of space for distal fixation and the unique anatomy of concave curvature create difficulties during operative treatment. The closely lying radial nerve is another major concern. The aim of this study was to determine whether anterolateral dual plate fixation could be effective for a distal junctional fracture of the humerus both biomechanically and clinically. A right humerus 3-dimensional (3D) model was obtained based on plain radiographs and computed tomography data of patients. Two fractures, a spiral type and a spiral wedge type, were constructed. Three-dimensional models of locking compression plates and screws were constructed using materials provided by the manufacturer. The experiment was conducted by using COMSOL Multiphysics, a finite element analysis, solver, and simulation software package. For the clinical study, from July 2008 to March 2021, a total of 72 patients were included. Their medical records were retrospectively reviewed to obtain patient demographics, elbow range of motion, Disabilities of the Arm, Shoulder and Hand (DASH) scores, Mayo Elbow Performance Scores (MEPS), and hand grip strength. No fracture fixation construct completely restored stiffness comparable to the intact model in torsion or compression. Combinations of the 7-hole and 5-hole plates and the 8-hole and 6-hole plates showed superior structural stiffness and stress than those with single lateral plates. At least 3 screws (6 cortices) should be inserted into the lateral plate to reduce the load effectively. For the anterior plate, it was sufficient to purchase only the near cortex. Regarding clinical results of the surgery, the range of motion showed satisfactory results in elbow flexion, elbow extension, and forearm rotation. The average DASH score was 4.3 and the average MEPS was 88.2. Anterolateral dual plate fixation was biomechanically superior to the single-plate method in the finite element analysis of a distal junctional fracture of the humerus model. Anterolateral dual plate fixation was also clinically effective in a large cohort of patients with distal junctional fractures of the humerus.

VATS Lung Resection in Bosnia and Herzegovina

Background: Video-assisted thoracic surgery (VATS) for both minor and major thoracic procedures has become routine practice worldwide. In this study, we present our experience with multiportal and uniportal VATS (MVATS and UVATS) in Bosnia and Herzegovina (B&H). MVATS and UVATS procedures were performed in two B&H Clinical Centers: Tuzla and Sarajevo. The first MVATS procedure at Tuzla Clinical Center was conducted in 2004, and the first UVATS lobectomy was performed in 2019. At Sarajevo Clinical Center, the initial MVATS took place in 2005, and the first UVATS lobectomy was carried out in 2020. Methods: We retrospectively analyzed 401 VATS procedures with prospective data, collected between 06/2017 and 04/2023. The VATS technique was employed for wedge resections, partial resections, lobectomies, and other types of resections, including metastasectomy. Results: Out of the 401 patients, 242 (60.34%) were male, and 159 (39.66%) were female, with a mean age of 57.2±23 years. The procedures consisted of 231 UVATS and 170 MVATS. Lobectomy was performed in 61 (15.21%) cases, wedge resections in 216 (51.37%), partial resections in 85 (21.19%), and other types of resections in 39 (9.72%) patients. The median duration of the procedure was 210 minutes for lobectomy, and 77.5 minutes for wedge and other types of resections. Major complications, such as bronchopleural fistula in 22 (5.49%) cases, wound infections in 20 (4.99%), atelectasis in 19 (4.74%), lung infiltrations in 15 (3.74%), and bleeding in 15 (3.74%) patients, were observed. The overall mean hospital stay for all procedures was 6.45 days. Conclusion: Uniportal and multiportal VATS techniques are feasible and safe for various indications in thoracic surgery. VATS can be performed in middle-income countries such as Bosnia and Herzegovina with acceptable results, by thoracic surgeons experienced in general thoracic surgery

Design of a concept wedge-shaped self-levelling railway sleeper

Differential railway track settlement can result in ballast voids, leading to sleepers that hang from the rail and are no longer supported by the ballast. These hanging sleepers are damage for track component. As a solution, this paper proposes and investigates a new concept sleeper with a wedge-shaped geometry, intended to stimulate the migration of ballast into any voids, thus reducing the occurrence of hanging sleepers. A series of scaled laboratory tests and 2D and 3D discrete element simulations are used to investigate different wedge-shaped geometries. The investigations include the wedge type (single long wedge versus multiple mini-wedges) and the wedge angle (30, 45, 60 degrees). First, the scaled laboratory tests are used to study the performance of different wedge geometries. Next, 3D DEM simulations are performed to analyse the contact forces in the ballast due to different wedge designs. Finally, 2D DEM simulations are performed to study the settlement behaviour. The main conclusions are that a single long wedge is preferable compared to multiple smaller wedges. when the wedge sleeper angle is larger than the ballast’s angle of repose, particles have the freedom to migrate into the settlement induced voids. Also, an increased wedge sleeper angle stimulates greater particle migration and thus improves the support correction. However the longer wedge also leads to a decrease in effective ballast height under sleeper which may make retrofitting on existing lines challenging.

Implementation of Lung-Protective Ventilation in Patients With Acute Respiratory Failure.

We implemented a computerized protocol for low tidal volume ventilation (LTVV) to improve management and outcomes of mechanically ventilated patients with, and without, the acute respiratory distress syndrome (ARDS). Pragmatic, nonrandomized stepped wedge type II hybrid implementation/effectiveness trial. Twelve hospitals in an integrated healthcare system over a 2-year period. Patients greater than or equal to 18 years old who had initiation of mechanical ventilation in the emergency department or ICU. We excluded patients who died or transitioned to comfort care on the day of admission to the ICU. We defined a subgroup of patients with ARDS for analysis. Implementation of ventilator protocols for LTVV in the ICU. Our primary clinical outcome was ventilator-free days (VFDs) to day 28. Our primary process outcome was median initial set tidal volume. We included 8,692 mechanically ventilated patients, 3,282 (38%) of whom had ARDS. After implementation, set tidal volume reported as mL/kg predicted body weight decreased from median 6.1 mL/kg (interquartile range [IQR], 6.0-6.8 mL/kg) to 6.0 mL/kg (IQR, 6.0-6.6 mL/kg) ( p = 0.009). The percent of patients receiving LTVV (tidal volume ≤ 6.5 mL/kg) increased from 69.8% ( n = 1,721) to 72.5% ( n = 1,846) ( p = 0.036) after implementation. The percent of patients receiving greater than 8 mL/kg initial set tidal volume was reduced from 9.0% ( n = 222) to 6.7% ( n = 174) ( p = 0.005) after implementation. Among patients with ARDS, day 1 positive end-expiratory pressure increased from 6.7 to 8.0 cm H 2 O ( p < 0.001). We observed no difference in VFD (adjusted odds ratio, 1.06; 95% CI, 0.91-1.24; p = 0.44), or in secondary outcomes of length of stay or mortality, either within the main cohort or the subgroup of patients with ARDS. We observed improved adherence to optimal ventilator management with implementation of a computerized protocol and reduction in the number of patients receiving tidal volumes greater than 8 mL/kg. We did not observe improvement in clinical outcomes.

Oncologic Outcome after Pulmonary Metastasectomy as Part of Multidisciplinary Treatment in a Tertiary Oncological Center

(1) Background: Pulmonary metastases are encountered in approximately one-third of patients with malignancies, especially from colorectal, lung, breast, and renal cancers, and sarcomas. Pulmonary metastasectomy is the ablative approach of choice, when possible, as part of the multidisciplinary effort to integrate and personalize the oncological treatment. (2) Methods: The study includes 58 consecutive cases of pulmonary metastasectomies, retrospectively analyzed, performed in 12 consecutive months, in which the pathology reports confirmed lung metastases. (3) Results: Most frequent pathological types of metastases were: 14 of colorectal cancer, 10 breast, 8 lung, and 8 sarcomas. At the time of primary cancer diagnosis, 14 patients (24.14%) were in the metastatic stage. The surgical approach was minimally invasive through uniportal VATS (Video-Assisted Thoracic Surgery) in 3/4 of cases (43 patients, 74%). Almost 20% of resections were typical (lobectomy, segmentectomy). Lymphadenectomy was associated in almost 1/2 of patients and lymph node metastases were found in 11.11% of cases. The mortality rate (intraoperative and 90 days postoperative) is zero. The OS after pulmonary metastasectomy is 87% at 18 months, and the estimated OS for cancer is 90% at 5 years. The worst outcome presents the patients with sarcomas and the best outcome-colorectal and lung cancer. The patients with 1 or 2 resected metastases presented 96% survival at 24 months. (4) Conclusions: After pulmonary metastasectomy, survival is favored by the small number of metastases resected (1 or 2), and by the dimension of metastases under 20.5 mm. The non-anatomic (wedge) type of lung resection may present a lower risk of death compared to lobectomy. No statistical significance on survival has the presence of lymphadenectomy, the laterality right/left lung, the upper/lower lobes. In the future, longer follow-up and prospective randomized trials are needed for drawing definitive conclusions.

Fracture edge features of diaphyseal clavicular fractures: A morphologic study.

Previous researchers used transverse fractures centered over the midpoint of the clavicle as the diaphyseal clavicular fracture models. However, as a result of shear stress concentration in sigmoid-shaped structures, most diaphyseal clavicular fractures have coronal fracture edges and are located distal to the midpoint. The purpose of this study was to quantify the morphology and utilize these parameters to establish clinically relevant fracture models. The computed tomographic DICOM data of 100 consecutive patients were included. We investigated the morphologic characteristics of the fracture edges after virtual fracture reduction. The fracture orientation was determined based on the normal vectors of the best-fit plane of the fracture edges. The fracture location was measured by the extreme points of the edges. The fracture configuration was evaluated using fracture maps. There were 28 simple, 43 wedge, and 29 multifragmentary types. Coronal oriented fracture edges accounted for more than 70% of the simple, wedge, and multifragmentary types. The most proximal point of the proximal edge was located at 46.7 (42.0-56.5), 47.6 (42.5-50.1), and 46.3 (42.0-49.3)% of the endpoint line in the simple, wedge, and multifragmentary types, respectively (P = 0.548). The most distal point of the distal edge was located at 72.2 (68.4-75.0), 73.2 (69.5-76.9), and 74.0 (69.6-77.1)% of the endpoint line (P = 0.353). The longest proximal main fragments occurred in the simple types at 71.9 (66.3-75.4)% of the endpoint line (P < 0.001), and the shortest distal main fragments occurred in the multifragmentary types at 55.8 (49.8-59.3)% of the endpoint line (P = 0.001). The heatmaps showed a high concentration of anteriorly distributed wedge fragments (88%; n=38/43) and coronally distributed multifragmentary fragments (62%; n=18/29). We showed that typical diaphyseal clavicular fractures have coronal fracture edges and are located within the distal half of the diaphyseal segment. The fractured fragments were initiated anteriorly in the wedge types and then propagated coronally in the multifragmentary types. The features of these fracture edges could be useful in designing osteotomy models and provide different perspectives of anterior and superior plating techniques.

New interlocking intramedullary nail for treating acute midshaft clavicular fractures in adults: A retrospective study.

The aim of this study was to retrospectively examine the radiological and functional results of midshaft clavicle fractures that were treated with a new, interlocking intramedullary nail, and employing a different locking option. Between January 2018 and January 2020, 24 displaced midshaft clavicle fractures were operated with new, interlocking intramedullary nail. Fractures were classified according to the AO/orthopedic trauma association classification, according to which there were 22 15.2.B (wedge) and 2 15.2.C (comminuted) fractures. The mean patient age was 35.5±14.2 (range: 18-63) years. Eighteen (75%) of the patients were male and six (25%) were female. Follow-up data were recorded at a minimum of 1 year (range 12-36 months), with an average of 21.5 months (SD±8). The mean interval between the injury and surgery was 4.1 (SD±2.3; range: 1-9) days. Full shoulder movements had been achieved by all patients, relative to the contralateral side. The mean constant score was 95.6 (SD±4.2; range 90-100), and the mean visual analog scale score was 0.8 (SD±0.8; range: 0-3). Union was achieved in all patients. The mean union time was 9.5 (SD±1.8; range 6-12) weeks as assessed by radiograph. Average shortening of the clavicle relative to the contralateral side was 3.4% (SD±1.1; range 1.1-6.3). One patient experienced implant irritation, implant removal was performed after 14 months. No implant migration, hardware loosening, implant breakage, or neurovascular damage occurred. One hypertrophic scarring developed. One wound detachment developed at the 3rd post-operative week. We think that this new intramedullary nail is a good alternative for wedge type fractures in adult, acute, displaced, and midshaft clavicle fractures.

Potensi longsor berdasarkan analisis kinematik pada area low wall PT. Bukit Asam Tbk, site Tanjung Enim, Sumatera Selatan

PT. Bukit Asam Tbk is an open-pit coal mining company in Muara Enim, Soutgh Sumatra. In open-pit mining activities, slope stability analysis is carried out to evaluate the mine in order to create a safe mining process. Several types of slope failure are associated with geological structures. This research was conducted to identify the type of landslides in the low wall area of Pit X PT. Bukit Asam Tbk and determine the slope stability factor based on discontinuity data using the scanline method at 8 observation points that represent the lithology of the low wall area. Methods used in this research is kinematic analysis, slope stability analysis on plane slide types and wedge. Based on the kinematic analysis, it was identified that the Pit X low wall area has the potential for plane and wedge type landslides with a relatively stable slopes.

The effect of waves in hydrodynamics, stratification, and salt wedge intrusion in a microtidal estuary

Waves have been found to modulate circulation, stratification, and sediment dynamics in several estuaries, mainly near the mouth. This study analyzes the effects of waves on the hydrodynamics, stratification process, and dynamics of the salt wedge in an estuary with a microtidal range, high fluvial and sediment discharges, and dominated by waves: the Magdalena River estuary (MRE). It is, under low flow conditions, a highly stratified, salt wedge type. Field measurements and the MOHID 3D modeling system, 2D coupled with the SWAN model, were used for this purpose. The low flow seasons of 2018 (February-March) and 2020 (March) were taken as case studies. Results show that when considering wave effects in the numerical simulations, more realistic conditions are reproduced in the circulation patterns and salinity distribution in the outer estuary. Variations in velocity patterns and salinity distribution are found between the mouth and 2 km upstream of the mouth when comparing the simulations with and without waves, especially in the mixing layer. These variations in hydrodynamics and stratification may be associated with increased wave-induced bed shear stress, variations in barotropic and baroclinic acceleration, and increased vertical mixing. At 2 km into the river channel, the reduction in wave height energy of 95% and changes in salinity distribution are already lower than 2%. In addition, it was observed that waves do not generate significant changes in the dynamics of the salt wedge, which is mainly affected by the diurnal tidal cycle, presenting variations in the length of the intrusion of up to 1 km, and in the magnitude of the longitudinal salinity gradient at the salt front, presenting low salinities at high tide when the wedge enters, and high salinities at low tide, in its retreat.

Permafrost and paleoenvironments on the Northeastern Qinghai-Tibet Plateau, China during the local last permafrost maximum

ABSTRACT The Qinghai-Tibet Plateau (QTP) is one of the middle- and low-latitude regions with the most developed and well-preserved periglacial phenomena and remains in the world. On the northeastern QTP, periglacial remains are widespread and vital for investigating the evolution of regional periglacial and permafrost environments. The recently discovered periglacial remains on the northeastern QTP are mostly cryogenic wedges of Late Pleniglacial age (30–10 ka), deep and large cryogenic wedges mostly formed during 30–19 ka ago. Shallow cryogenic wedges have formed between 16 and 12.5 ka. A second wave of cryogenic wedge pseudomorphs seems to have followed, which was ending by about 7 ka. Based on the types of cryogenic wedges and in combination with stratigraphic data for dating, as well as the past Quaternary geological and periglacial landform data, we infer that the mean annual air temperature (MAAT) in this region during the local LPM (30–19 ka) was 7–9°C lower than that at present, and the lower limit of permafrost was lowered to about 2,200–2,500 m a. s. l. During the local LPM, permafrost was extensively and intensively developed on the northeastern QTP, and the continuous permafrost zone extended down to the source area of the Yellow River and the vicinity of the Zoîgé Plateau in the east. Next, discontinuous, sporadic and patchy permafrost occur in cascadingly lowering zones.

Energy Conservation Optimization and Numerical Simulation of Urban Green Space Landscape Pattern

In order to alleviate the urban heat island effect, absorb harmful gases, reduce temperature, and increase humidity, a method of energy conservation optimization and numerical simulation of urban green space landscape pattern is proposed. Based on the theory of landscape ecology, green wedge, green belt, green road, park, and other types of green space with different ecological functions are designed in Shenyang, and an optimization scheme of urban green space network spatial structure of “four belts, three rings, seven wedges, and network connection” is formed. Combined with remote sensing (RS) and geographic information system (GIS) spatial analysis technology, the atmospheric environment effect under the influence of green space landscape optimization pattern in summer based on computational fluid dynamics (CFD) numerical simulation technology is analyzed, and the corresponding optimization strategies of urban green space planning are put forward. The simulation results show that in the bottom wind speed field of 1.5 m, the area ratio of 0∼0.375 m/s wind speed is 15.87%, and the area ratio of 2.625∼3 m/s wind speed is 32.06%. In the bottom concentration field of 1.5 m, the spatial diffusion capacity of SO2 pollutants is enhanced, and the concentration of pollutants is relatively low. The area ratio of SO2 concentration is 10.06% in the range of 0.1292∼0.1551 mg/m3, and the area ratio of SO2 concentration is 68.08% in the range of 0∼0.05169 mg/m3. It is concluded that the spatial diffusion of wind speed, SO2, and temperature is closely related to the urban spatial layout. The optimal spatial layout of urban green space can effectively alleviate the urban heat island effect, promote the spatial diffusion of SO2, and better form the urban ventilation corridor. The research on atmospheric environmental effects of urban green space based on CFD can effectively simulate and evaluate the optimization measures and conceptual design of urban green space system planning, and also provide new ideas for the quantitative planning of urban green space system.

Soil failure mechanisms during installation and inclined pullout of stiffened suction caisson in calcareous silt

Soil failure mechanisms of stiffened suction caisson during installation and inclined pullout in calcareous silt have been investigated through centrifuge model tests and small strain finite element analyses (FEA). In the tests, a model half-caisson was installed followed by loading at a 45° inclination. Digital images were captured and subsequently analysed using particle image velocimetry (PIV), allowing soil failure mechanisms to be observed. The FEA were carried out to study the effects of pullout angles for caissons with and without internal suction. The PIV results revealed that during suction assisted installation, localised shear strains develop surrounding the skirt. As the stiffeners penetrated into the soil, the particles filled up the gaps between the inside wall and soil plug. During inclined pullout, a double wedge type failure was observed at the front and rear sides that extended to 1.5 caisson diameter at the soil surface. A pure shear type failure was observed around the skirt tip. The FEA results showed that, for caissons without internal suction, a wedge failure mechanism was prevalent. The size of the wedge decreased with increasing pullout angle. For caissons with internal suction, a rotational failure mechanism was apparent.

Translated article] Syndesmosis injury associated with high-energy tibial shaft fractures: Case series of a misdiagnosis rupture

IntroductionAnkle syndesmosis injuries can be associated with a spiral mechanism on tibial shaft fractures. We are not aware if there is evidence of the incidence of ipsilateral syndesmotic lesson associated to high-energy tibial shaft fracture mechanisms. The aim of this study was to analyze the incidence of syndesmotic injuries associated with high-energy tibial shaft fractures. MethodsTwo hundred thirty-three diaphyseal tibial fractures operated between January 2007 and January 2017, the fracture patterns were analyzed, they were classified according to AO, the talocrural angle was measured, they analyzed failures and reoperations and described a novel failure method. ResultsFrom a total of 234 fractures that met the inclusion criteria, 159 (64.96%) suffered closed fractures and 75 (32.05%) where open fractures. According to the AO classification system: 152 (64.10%) were simple patterns 42.A; 49 (20.94%) wedge type patterns 42.B and 33 (14.10%) complex patterns 42.C. Ten patients, a 4.27% of the sample, shown an increased talocrural angle in the postoperative radiographs, evidencing shortening of the fibula. Nine patients underwent surgery, the remaining patient was lost to follow-up. All the treated patients presented restoration of the normal talocrural angle. ConclusionThe incidence of syndesmotic injuries associated with high-energy tibial shaft fractures reaches 4.27%. We think that is necessary to evaluate the ankle and syndesmosis in all tibial shaft fractures, even with high-energy patterns, not only in spiral patterns.

Subduction erosion and basal accretion in the Central Chile subduction wedge inferred from local earthquake tomography

We analyze records of ambient seismicity from Central Chile to investigate mechanisms of tectonic erosion and accretion in an Andean margin. The seismograms were recorded by a temporary network of 39 stations deployed between 32.5°S and 34.0°S from April to November 2017. We employ an automatic earthquake catalogue generator to estimate 8463 P-wave and 5482 S-wave arrival times from 924 hypocenters, which were then used to jointly determine hypocenters and 3D models of Vp and Vp/Vs. Previous investigations of the nearby Illapel region suggest that the Coastal Cordillera acts as a subduction wedge, at the bottom of which are accreted crustal slices detached from the overriding plate by tectonic erosion. These slices may be subducted beyond the downdip frictional limit in a way that differs from a traditional orogenic wedge (type A-subduction). Our results reveal a wedge geometry with: (1) body wavespeed anomalies near the interplate contact below 30 km depth, which we interpret as accretionary complexes formed by basal accretion of crustal slices, and (2) latitudinal differences of those anomalies, which we attribute to eroded material from both plates that changes the basalt-eclogite transition depth in the subducted Nazca plate. Based on these, we infer that the development of this basal accretionary complex by subduction erosion could be responsible for the uplift of Coastal Cordillera in Central Chile, and that the retroshear zone of the subduction wedge is controlled by local conditions inside the mantle wedge. Moreover, we suggest that the accretionary complex beneath the Central Chile subduction wedge behaves as seismic barrier that can explain the 1985 Mw 8.0 Valparaíso earthquake slip distribution and the southeastward migration of aftershocks of 2017 Mw 6.9 Valparaíso earthquake. Finally, we suggest that the subduction wedge influences continental structures on a scale of millions of years.

Ancient and recycled sulfur sampled by the Iceland mantle plume

Stable sulfur isotope ratios of mid-ocean ridge and ocean island basalts (MORBs and OIBs) preserve unique information about early Earth processes and the long-term volatile cycles between Earth's mantle and the surface. Icelandic basalts present ideal material to examine the oldest known terrestrial mantle reservoir, accessed through a deep-rooted mantle plume, but their multiple sulfur isotope systematics have not been explored previously. Here, we present new sulfur concentration (30–1570 ppm) and isotope data (δ34S = −2.5 to +3.8‰ and Δ33S = −0.045 to +0.016‰; vs. Canyon Diablo Troilite) from a sample suite (n = 62) focused on subglacially erupted basaltic glasses obtained from Iceland's neovolcanic zones. Using these data along with trace element systematics to account for the effects of magmatic processes (degassing and immiscible sulfide melt formation) on δ34S, we show that primitive (MgO > 6 wt.%), least degassed glasses accurately record the δ34S signatures of their mantle sources. Compared to the depleted MORB source mantle (DMM; δ34S = −1.3±0.3‰), the Iceland mantle is shown to have a greater range of δ34S values between −2.5 and −0.1%. Similarly, Icelandic basalts are characterized by more variable and negatively shifted Δ33S values (−0.035 to +0.013‰) relative to DMM (0.004±006‰). Negative δ34S-Δ33S signatures are most prominent in basalts from the Snæfellsnes Volcanic Zone and the Kverkfjöll volcanic system, which also have the lowest, most MORB-like 3He/4He (8–9 R/RA, where RA is the 3He/4He of air) and the highest Ba/La (up to 12) in Iceland. We propose that subduction fluid-enriched, mantle wedge type material, possibly present in the North Atlantic upper mantle, constitutes a low-δ34S-Δ33S component in the Icelandic mantle. This suggests that volatile heterogeneity in Iceland, and potentially at other OIBs, may originate not only from diverse plume-associated mantle components, but also from a heterogeneous ambient upper mantle. By contrast, a set of samples with high 3He/4He (up to 25.9 R/RA) and negative μ182W anomalies define an ancient lower mantle reservoir with a near-chondritic Δ33S and δ34S signature of ∼0‰. The difference between DMM and the high high-3He/4He mantle may reflect separate conditions during core-mantle differentiation, or a previously unidentified flux of sulfur from the core to the high-3He/4He reservoir.