Mesh System Research Articles

Optimal location and sizing of renewable distributed generations and electric vehicle charging stations

Many countries are aiming to replace gasoline-based vehicles with electric vehicles (EVs). The increasing adoption of EVs has led to a surge in the number of charging stations, significantly impacting the electrical grid with issues such as power quality degradation, increased losses, and voltage fluctuations. In response to these challenges, there is a growing interest in integrating distributed generation from unconventional and renewable sources into the grid to power EV Charging Stations (EVCSs). However, this integration poses new complexities, including increased power losses and voltage instability. Consequently, the optimal allocation and sizing of Renewable Distributed Generations (RDGs) and EVCSs have become critical planning considerations. This paper addresses these issues by formulating a multi-objective optimization problem aimed at minimizing power losses and improving the voltage profile of distribution systems. The study introduces several constraints, including the placement of EVCSs and RDGs at separate buses, and employs particle swarm optimization and cuckoo search algorithm to simultaneously determine the optimal locations and sizes of the RDGs and the optimal locations of the EVCSs. The effectiveness of the proposed techniques is demonstrated through simulations on IEEE 33 radial and meshed distribution systems, illustrating their capability to identify optimal configurations for integrating RDGs and EVCSs.

Experimental Investigation into Deploying a Wi-Fi6 Mesh System for Underground Gold and Platinum Mine Stopes

Stopes suffer from unreliable wireless communication due to their harsh environment. There is a lack of confidence within industry regarding the effectiveness of existing solutions in providing reliable high-bandwidth performance in hard rock stopes. This work proposes that Wi-Fi6 is a good candidate for reliable high-bandwidth communications in underground hard rock stopes. Experiments in a tunnel and mine stope were conducted to evaluate the performance of Wi-Fi6 in terms of latency, jitter, and throughput. Different criteria, such as multi-hop systems, varying multipath, mesh routing protocols, and frequencies at different bandwidths, were used to evaluate performance. The results show that Wi-Fi6 performance is greater in stopes compared to tunnels. Signal quality evaluations were conducted using the Asus RT-AX53U running OpenWrt, and an additional experiment was conducted on the nrf7002dk running Zephyr OS to evaluate the power consumption of Wi-Fi6 against the industry standard for low-powered wireless communications, IEEE 802.15.4. Wi-Fi6 was found to be more power-efficient than IEEE 802.15.4 for Mbps communications. These experiments highlight the signal robustness of Wi-Fi6 in stope environments and also highlights its low-powered nature. This work also highlights the performance of the two most widely used open-source mesh routing protocols for Wi-Fi.

Re-patterning of cylindrical packing of diblock copolymers under confinement and curvature effects by using approximations of PDE’s involved in the CDS model on polar mesh system

Soft materials, including diblock copolymers, are advancing nanotechnology due to their unique properties, applications materials include energy harvesting, water sanitation, environmental treatment, nanosensors, drug delivery and nanolithography. These materials are light, cheap, efficient, sensitive, durable and more functional, whose new morphologies have been predicted by mathematicians through simulation. This work produces and predicts the pattern of packing of nano-cylinders by using confinement to appreciate the frustration in the packing of nano-cylinders under the influence of curvature. In this contribution, the cell dynamic simulations model is used to examine the impact of circular annular pore confinement on system orientation toward cylindrical morphologies. A 9-point stencil approximates the isotropic Laplacian by finite-difference discretization on a polar grid to meet the requirement of a cell dynamic simulation model. FORTRAN codes are generated for the set of PDEs included in the CDS model. OPEN DX is used to visualise the predicted cylindrical patterns. The consistency of our results with experimental observations makes our research valid and significant.

Effect of tooth surface wear on dynamic characteristics of spur gear transmission system

The meshing stiffness and system dynamic characteristics caused by gear wear fault are studied. Firstly, potential energy method was used to model and solve the meshing stiffness of gears and the effect of wear on the meshing stiffness and static transfer error was analyzed. A 6-dof spur gear dynamics model was established considering various nonlinear factors, and the dynamic responses of the spur gear system under various wear degrees were analyzed by using time domain, spectrum, phase plane, and Poincare mapping. Finally, the visual test platform of the gear box is built, and the wear condition and dynamic response of the gear box under different wear cycles are analyzed. Results show that the meshing stiffness of gear decreases due to wear, and the meshing stiffness of double tooth decreases more than that of single tooth. In addition, the static transmission errors caused by wear changes periodically with meshing frequency. Wear causes the vibration response of gear system to become complex gradually, and the nonlinear of the system is enhanced, which changes from single period motion to quasi period motion. Results can provide theoretical support for gear wear reduction, life extension, vibration reduction, and noise reduction and lubrication improvement.

Durability of externally strengthened concrete prisms with CFRP laminates and galvanized steel mesh attached with epoxy adhesives and mortar

The long-term bond degradation and strength retention of flexural bond prisms strengthened with carbon fiber-reinforced polymer (CFRP) composite and galvanized steel mesh (GSM) systems, bonded to concrete using epoxy adhesives and cement-based mortar under aggressive conditioning regimes are compared in this paper. Notched prisms strengthened using low-cord density steel mesh (LSM) with epoxy (SME-strengthened) and cement mortar (SMM-strengthened), and CFRP-epoxy systems were weathered under saline water and direct sunlight for a period of 28 and 540 days. The results of the study were analyzed based on experimentally obtained ultimate load (Pu) values and empirically calculated average bond shear stress (τavg) and prism strength retention (Rp) values. The bond strength degraded by 39 and 34 % in CFRP strengthened, 2.9 and 33 % in SME strengthened, and 2.8 and 10.8 % in SMM-strengthened specimens following the 540-day exposure to saline water and direct sunlight, respectively. The average prism retention ratio was calculated to be 0.61 and 0.66 for CFRP-strengthened, 0.97 and 0.67 for SME-strengthened, and 0.97 and 0.89 for SMM-strengthened specimens after 540 days of saline water and direct sunlight exposure. Flexural prism environment strength reduction factors (CE) were proposed as 0.60, 0.95, and 0.95 for CFRP, SME, and SMM-strengthened specimens under saline water exposures and 0.65, 0.65, and 0.85 for CFRP, SME, and SMM strengthened specimens under direct sunlight exposures. Saline water exposure was observed to be most critical to all strengthening systems. Although CFRP-strengthened specimens showed minimum degradation in load-carrying capacity under both conditioning regimes, they showed maximum bond strength reduction in contrast to SMM-strengthened specimens. It was observed that the choice of bonding agent significantly influenced the extent of bond strength degradation under extreme exposure regimes, like those that prevail in the UAE and the Persian Gulf.

Learning model combining convolutional deep neural network with a self-attention mechanism for AC optimal power flow

Alternating current optimal power flow (OPF) analysis is critical for efficient and reliable operation of power systems. For large systems or repetitive computations, the traditional methods such as the direct and gradient methods, or non-traditional methods, such as the genetic algorithm and simulating annealing, are time-consuming and unsuitable for real-time computing. The work in this paper proposes a novel framework to obtain the optimal solution of power flow in real-time using a combination of convolutional neural networks and a self-attention mechanism. All parameters of the power networks are rearranged in an image-like shape of a multi-channel image where each channel is a two-dimensional matrix. The proposed approach is adaptive with every input size of power systems as well as frequent variations of network topologies without intervention to the framework core. The encompassment of all power system contexts in which all parameters of internal elements, generation costs, and topology information are included, contributes to the higher accuracy of inference compared to other current machine-learning-based OPF-solving methods. Besides, the proposed framework established on ubiquitous platforms is effortlessly integrated into current infrastructures of power systems, and the great efficiency along with the computation speed may serve as a critical point for practical implications, such as enabling faster decision-making during real-time operations, predicting system contingencies, and remedial actions based on an offline pre-trained model. This supervised learning process is applied to the dataset of four case studies of meshed power systems: the IEEE 5-bus system (IEEE-5), the IEEE 30-bus system (IEEE-30), the IEEE 39-bus system (IEEE-39), and the IEEE 57-bus system (IEEE-57) to prove the efficacy of the proposed method.

Graphene-integrated mesh electronics with converged multifunctionality for tracking multimodal excitation-contraction dynamics in cardiac microtissues

Cardiac microtissues provide a promising platform for disease modeling and developmental studies, which require the close monitoring of the multimodal excitation-contraction dynamics. However, no existing assessing tool can track these multimodal dynamics across the live tissue. We develop a tissue-like mesh bioelectronic system to track these multimodal dynamics. The mesh system has tissue-level softness and cell-level dimensions to enable stable embedment in the tissue. It is integrated with an array of graphene sensors, which uniquely converges both bioelectrical and biomechanical sensing functionalities in one device. The system achieves stable tracking of the excitation-contraction dynamics across the tissue and throughout the developmental process, offering comprehensive assessments for tissue maturation, drug effects, and disease modeling. It holds the promise to provide more accurate quantification of the functional, developmental, and pathophysiological states in cardiac tissues, creating an instrumental tool for improving tissue engineering and studies.

Micromorphology and thematic micro-mapping reveal differences in the soil structuring traits of three arbuscular mycorrhizal fungi

Arbuscular mycorrhizal (AM) fungi contribute to soil structure, but little is known about the effect of individual fungal species on soil aggregation. In this study, the influence of 3 AM fungi species on soil aggregation in a Vitric Andosol was determined using physical, micromorphological, and imaging analyses. We used a pipe of polyvinyl chloride (PVC) with a six-way connector, which was filled with soil plus AM fungal inoculum (Funneliformis mosseae, Rhizophagus intraradices, Gigaspora gigantea or non-inoculated -control-). Then lateral pipe connectors (experimental units) were covered with mesh systems (0.5, 0.25, and 0.034 mm), and PVC tubes filled with sterile soil were connected laterally using a clamp. The greenhouse experiment consisted of four treatments each with 32 experimental units. Four experimental units of each treatment were separated and collected at different times during the year: three were used to determine water-stable aggregates (disturbed soils), and one was preserved (undisturbed soil) to elaborate soil thin sections. Thematic micro-maps were constructed with image mosaics from a whole soil thin section, and micromorphological analyses were conducted using spatial operators. Our results showed that AM fungi affect soil aggregation forming micro-aggregates and macro-aggregates of different sizes. The most significant effects were observed with F. mosseae > R. intraradices >Gi. gigantea > control. Aggregation hierarchy was observed in micromorphological analysis, where F. mosseae and R. intraradices start binding organo-mineral particles and microaggregates to form macroaggregates, modifying soil structure from intergrain (apedal= without peds) to crumb aggregates (pedal= with peds). Gigaspora gigantea only promoted macroaggregation, by associating with pumice particles. The two AM fungi from Glomeraceae possess similar morphology compared to that isolate belonging to Gigasporaceae, which explain in part, their differential contribution traits on soil aggregation, as highlighted by using together physical and micromorphological analyses of soil thin sections based on high-resolution image mosaics.

IMPROVEMENT OF DESIGN PARAMETERS OF INERTIAL TYPE FUEL CONTINUITY SYSTEMS

Multiple restart of liquid-propellant rocket engines of spacecraft in zero gravity is one of the most difficult tasks that arise in the creation of new products of rocket technology. When performing a flight task, due to the movement of the spacecraft along the passive section of the trajectory, the components of the liquid fuel are mixed with the pressurized gas in its tanks in an arbitrary manner. There is a possibility that the gas phase will be located close to the drain hole. At the time of re-turning on the propulsion engines of the spacecraft, along with fuel, gas bubbles will enter the consumable line from the tank, which can, in turn, cause a failure of their launch.
 In order to avoid this emergency, special fuel continuity systems are used. Despite the significant diversity of these systems, all of them have significant shortcomings and limited working conditions. The main purpose of using fuel continuity systems of any type is to prevent the penetration of boost gas from the tank cavity into the flow line until the tank is completely emptied.
 The paper is devoted to the analysis of the possibilities of improving the design parameters of the two most common systems for ensuring fuel continuity by creating a combined "hybrid" system on their basis. Inertial and mesh systems for ensuring fuel continuity are considered. Theoretically, an analysis of the possibility of reducing the effect of pre-start acceleration for an inertial system for ensuring fuel continuity due to the use of a mesh phase separator in the fuel supply system is carried out. The paper considers the main design parameters of this combined system, which directly affect the level of its technical perfection, as well as the possibilities of their optimization.
 The results of the work can be useful in engineering practice in the creation of new promising products of rocket and space technology.

Provisioning of Fog Computing over Named-Data Networking in Dynamic Wireless Mesh Systems.

Fog computing is today considered a promising candidate to improve the user experience in dynamic on-demand computing services. However, its ubiquitous application would require support for this service in wireless multi-hop mesh systems, where the use of conventional IP-based solutions is challenging. As a complementary solution, in this paper, we consider a Named-Data Networking (NDN) approach to enable fog computing services in autonomous dynamic mesh formations. In particular, we jointly implement two critical mechanisms required to extend the NDN-based fog computing architecture to wireless mesh systems. These are (i) dynamic face management systems and (ii) a learning-based route discovery strategy. The former makes it possible to solve NDN issues related to an inability to operate over a broadcast medium. Also, it improves the data-link layer reliability by enabling unicast communications between mesh nodes. The learning-based forwarding strategy, on the other hand, efficiently reduces the amount of overhead needed to find routes in the dynamically changing mesh networks. Our numerical results show that, for static wireless meshes, our proposal makes it possible to fully benefit from the computing resources sporadically available up to several hops away from the consumer. Additionally, we investigate the impacts of various traffic types and NDN caching capabilities, revealing that the latter result in much better system performance while the popularity of the compute service contributes to additional performance gains.

Design Optimization of Blade Tip in Subsonic and Transonic Turbine Stages—Part I: Stage Design and Preliminary Tip Optimization

Abstract Rotor blade tip has significant influence on turbine stage aerodynamics and heat transfer. Most previous efforts have been based on low-speed cascade settings. However, more recent research on transonic blade tips exhibits distinctive flow features with qualitatively different performance sensitivities. These prompt two key issues of interest on the related flow conditioning. First, the contrast between a low-speed flow and a transonic regime highlights the less studied high-subsonic flow regime, closely relevant to many realistic turbine designs. Second, the relative casing movement and upstream inflow conditions, known to have non-negligible effects, indicate the need to examine a rotor blade tip in a realistic stator–rotor stage environment, which is also lacking. To elaborate the Mach number effect in the flow regimes of practical interest, we aim to examine a high subsonic stage in a direct and consistent comparison with a transonic one. To this end, a high subsonic stage (exit Mach number of 0.7) and a transonic (exit Mach number of 1.1) are designed at the same Reynolds number with a three-dimensional parameterization and meshing system. The tip squealer height is used as a representative parameter to investigate the sensitivity of the stage aerothermal performance. The multi-objective optimization using the Kriging surrogated model is employed to identify the Pareto fronts for the stage efficiency and the heat transfer. The comparison of the optimized results between these two stages shows distinctively different trends in the performance variation with the squealer height. The efficiency of the subsonic stage increases with the squealer height reaching a plateau. In contrast, the efficiency in the transonic stage first increases and then drops to the level comparable to that of a flat tip. Significantly, the present results indicate, for the first time, that the squealer tip in a transonic stage may not be as effective as in a subsonic stage. On the other hand, for heat transfer, sensitivity variations are more complex. The overall heat load and the local nonuniformity lead to qualitatively different sensitivities with the squealer height, as well as completely incomparable Pareto fronts. These observed heat transfer sensitivities raise the question on how to effectively conduct a combined aerodynamic and heat transfer performance design optimization. The authors subsequently resort further aerothermal physics analyses described in a companion paper as Part II of the two-part article. In Part II, the physical interpretation of the contrasting aero-efficiency sensitivities for the two stages, as well as a physical understanding leveraged selection of the objective function for such combined blade tip aerothermal optimization will be presented.

Evaluation of Efficacy of Different Plating Systems in ZMC Fractures: An Original Research

ABSTRACT Objective: This study’s objective was to assess and contrast the performance of several plating techniques in the treatment of zygomaticomaxillary complex (ZMC) fractures. Group A (Microplate System), Group B (Titanium Mesh System), and Group C (Absorbable Plate System) plating systems were the ones that were studied. Materials and Methods: With 10 patients in each group, a retrospective analysis of 30 patients with ZMC fractures was done. The following information was gathered: fracture reduction, stable fixation, complications, and patient satisfaction. Analysis was done on patient-reported outcomes, surgical outcomes, and demographic factors. Results: Group B (Titanium Mesh System) came in second with rates of 70% and 80%, respectively, while Group A (Microplate System) showed the highest rates of fracture reduction (90%) and stable fixation (100%). For fracture reduction and stable fixation, Group C (Absorbable Plate System) demonstrated rates of 80% and 90%, respectively. For Groups A, B, and C, the complication rates were 20%, 30%, and 10%, respectively. For Groups A, B, and C, the patient satisfaction levels were 90%, 80%, and 70%, respectively. Conclusion: According to the results, the Microplate System (Group A) is better than the Titanium Mesh System (Group B) and the Absorbable Plate System (Group C) in terms of fracture reduction and stable fixation when treating ZMC fractures. All plating systems had acceptable complication rates, and overall patient satisfaction ratings were high. Fracture features and patient-specific considerations should be taken into account while making individualized treatment options.

Morphological Investigation of Lamellae Patterns in Diblock Copolymers under Change of Thickness and Confinement in Polar Geometry

Mathematicians collaborate computationally with practical scientists to predict the novel morphologies soft materials, having potential applications in nanotechnology. This work presents the novel lamellae morphology that the confined diblock copolymer system displayed inside the polar geometry in order to achieve this, cell dynamics simulations (CDS) model is employed on a polar mesh to study the special impacts of confinement on the self-assembly behavior of diblock copolymer systems. Under the numerical formulation of the isotropic Laplacian with polar geometry employed in the CDS model, the set of 9-point stencil is considered to discretize the Laplacian operator on polar mesh system. FTCS finite difference mechanism is taken into consideration for discretization of Laplacian operator due to its computational efficiency and accuracy. Cell dynamics simulation is efficient simulation model for large-scale simulation as compared to the other models available in literature. In the simulation, evolutionary lamella morphology is presented with and without confinement for various sizes of the circular annular pores. A comparative review of lamella morphologies achieved by simulation in comparison of experimental study is presented, coupled with a thorough investigation of symmetric and asymmetric morphologies in captivity.

Discretization of Laplacian Operator on 19 Points Stencil Using Cylindrical Mesh System with the Help of Explicit Finite Difference Scheme

Discretization of Laplacian Operator on 19 Points Stencil Using Cylindrical Mesh System with the Help of Explicit Finite Difference Scheme

Customer Orientated Indices and Reliability Evaluation of Meshed Power Distribution System

Aim. Reliability evaluation of a system or component or element is very important in order to predict its availability and other relevant indices. Reliability is the parameter which tells about the availability of the system under proper working conditions for a given period of time. The study of different reliability indices are very important considering the complex and uncertain nature of the power system. In this paper reliability evaluation of the meshed distribution system is presented. This paper also evaluates basic indices such as average failure rate, average outage time and average annual outage time. Along with basic indices, customer orientated indices such as system average interruption frequency index, system average interruption duration index and customer average interruption duration index of an electrical power distribution system is also evaluated. The electrical power distribution system taken for study is meshed distribution system in nature.Aditya Tiwary. "Customer Orientated Indices and Reliability Evaluation of Meshed Power Distribution System" Reliability: Theory & Applications, vol. 15, no. 1, 2020, pp. 10-19. doi:10.24411/1932-2321-2020-11001

Embedding Dependencies Between Wind Farms in Distributionally Robust Optimal Power Flow

The increasing share of renewables in the electricity generation mix comes along with an increasing uncertainty in power supply. In the recent years, distributionally robust optimization has gained significant interest due to its ability to make informed decisions under uncertainty, which are robust to misrepresentations of the distributional information (e.g., from probabilistic forecasts). This is achieved by introducing an ambiguity set that describes the potential deviations from an empirical distribution of all uncertain parameters. However, this set typically overlooks the inherent dependencies of uncertainty, e.g., spatial dependencies of weather-dependent energy sources. This paper goes beyond the state-of-the-art models by embedding such dependencies within the definition of ambiguity set. In particular, we propose a new copula-based ambiguity set which is tailored to capture any type of dependencies. The resulting problem is reformulated as a conic program which is kept generic such that it can be applied to any decision-making problem under uncertainty in power systems. Given the Optimal Power Flow (OPF) problem as one of the main potential applications, we illustrate the performance of our proposed distributionally robust model applied to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i)</i> a DC-OPF problem for a meshed transmission system and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ii)</i> an AC-OPF problem using <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LinDistFlow</i> approximation for a radial distribution system.

Performance of wildlife fence systems under animal impact load

Wildlife fence protection systems specifically designed for animal protection are critical in mitigating wildlife-vehicle collisions and preserving animal habitats. These systems are quite similar to rockfall barrier systems, which are well studied and developed, however, few studies are specifically oriented toward investigating structural performance of these systems. Despite the similarities, results of studies related to rockfall barriers may not be directly applicable to design and performance evaluation of wildlife barrier systems due to differences in a range of size, shape, and velocity of impactors and structural details. This study aims to bridge this gap by analyzing performance and capacity of wildlife structures in more detail through parametric study with consideration of a wide range of properties and structural details appropriate for these systems, such as mesh type (square and inclined), mesh size, and wire diameters. The behavior of these systems under impact loads is simulated using nonlinear finite element models with consideration of ductile damage and element removal techniques to accurately capture wire rupture and changes in the impactor-fence system interface. The results demonstrate that the response of the system is highly influenced by factors such as mesh type, opening size, wire diameter, and impactor size. Notably, the system utilizing an inclined mesh type exhibits a 35 % higher failure velocity, 50 % greater energy dissipation, and 21 % less maximum displacement compared to the square mesh system. The detailed results and discussions in this study provide valuable insights into the influence of individual parameters on the behavior of wildlife fence systems, aiding in the design of more efficient wildlife barrier systems with enhanced performance.

Application of a VOF Multiphase Flow Model for Issues concerning Floating Raft Aquaculture

Floating raft aquaculture has gradually become a mainstream aquaculture model in the waters of Changhai County, Dalian. To quantitatively describe the impact of floating raft aquaculture facilities on the hydrodynamic environment of nearby sea areas, in this study, we took a single floating raft aquaculture structure as the research object and built a numerical prediction model for water flows passing through the floating raft aquaculture structure using a six-degree-of-freedom VOF (volume of fluid) multiphase flow simulation method based on an overset moving mesh system. Then, we verified the numerical model by utilizing oblique hydraulic jumps and water flows passing through a submerged bar. As shown by the findings, the simulated values are in good agreement with the theoretical solutions and measured values, indicating that the model features high precision and great stability. The impact of the raft area on the hydrodynamic force was introduced into the source term of an equation for consideration. In order to further determine the hindering effect of the raft body on the water body, transport equations and the tracer method were used to simulate the impact of floating raft aquaculture facilities on the water exchange performance of nearby sea areas. This study shows that the VOF multiphase flow model can be easily and accurately applied to studies on floating raft aquaculture, which can greatly reduce the limitations of experiments that utilize pure hydraulic models, wherein the impacts of floating raft aquaculture facilities on hydrodynamic force are generally considered simply based on observations, water roughness or the secondary drag force coefficient, thereby effectively improving the scientific understanding of the physical mechanism involved in floating raft aquaculture.

Surgical and Clinical Outcomes Associated With the Use of Barbed Sutures and Self-Adhering Mesh System and Polymeric Glue for Wound Closure in Multilevel or Revision Spinal Surgery: A Matched Cohort Comparative Study With Conventional Wound Closure Procedure.

Multilevel or revisional posterior spinal surgery is prone to infection and delayed wound healing, related with the wound closure time and suture strength. Knotless barbed suture is an innovative self-locking, multianchor suture. This study aims to evaluate the safety and efficacy of the knotless barbed suture and self-adhering mesh with polymeric glue in multilevel or revisional posterior spinal surgery. This is a single-center retrospective matched cohort study. Patients were divided into 2 groups based on the wound closure method: barbed suture group with novel wound closure, and conventional suture group with conventional wound closure, 1:1 matched by the level of surgery and sex, resulting in 120 subjects each. Total operation time and wound closure time were measured intraoperatively, and perioperative clinical outcome parameters including postoperative wound complication were investigated for the first 3 months postoperatively. The distribution of continuous variables was assessed for normality by Shapiro-Wilk test, then parametric or nonparametric tests were applied accordingly (paired t-test or Wilcoxon signed-rank test). Wound closure time was significantly shorter with the novel barbed suture than with conventional suture in all subgroups divided by the level of spinal surgery: 3-5, 6-9, ≥ 10 levels (p < 0.001). The 2 groups showed no significant differences in surgical complications (p = 1.000). Specially, total operation time and wound-closing time were significantly shorter in revisional subgroup. Absorbable knotless barbed suture and self-adhering mesh with polymeric glue can shorten spinal wound closure time with noninferiority in complications for multilevel or revisional spinal surgery.

Analysis of ex-vessel debris bed formation of multi-material and multiphase composition based on coupled system of MELCOR2 and THERMOS–JBREAK/MSPREAD

THERMOS is being developed to analyze the multidimensional process by which molten debris released from the lower head of the reactor pressure vessel forms a non-uniform debris bed. THERMOS consists of four modules, JBREAK, DPCOOL, MSPREAD and REMELT. To evaluate a wide range of ex-vessel debris bed formation, the authors have developed the coupled system composed of the integrated severe accident (SA) analysis code MELCOR2, THERMOS-JBREAK and THERMOS-MSPREAD. JBREAK simulates the molten jet release and impingement on the cavity floor using the separated flow model consisting of the molten jet and particle debris. MSPREAD simulates the melt spread as the multi-layered structure composed of the partially solidified molten debris, the upper and lower crusts growing on both sides using the shallow water equation.The conversion algorithm of the multi-material and multiphase composition of the released molten jet calculated by MELCOR2, which is based on lumped parameters, to the composition suitable for THERMOS, which is based on distributed parameters, is recognized to be critical to the success of this system and has been implemented as the Python script MELTHER. This conversion also includes the contribution of suspended particles embedded in the molten jet to the viscosity of partially solidified molten debris. As the JBREAK–MSPREAD interface, the method of overlapping the mesh systems of the two codes was implemented to solve the multidimensional flow equations in the near impinging region. Filtration of the molten debris inside the particle layer at the jet-impinging point was modeled using the particle debris deposition and molten debris filtration models.This coupled system was applied to a station blackout scenario in a typical BWR3 Mark-I plant, where approximately 14 tons of mixed molten and particle debris were released from the lower head and impinged on the pedestal floor. The calculation space was set to handle molten jet falling, impingement on the floor, and spreading from the pedestal to the outside dry well region. Complex anisotropic melt spreading was analyzed on the dry pedestal floor with two sumps covered with thin lids and a low weir at the bottom of the slit made in the cylindrical wall separating the pedestal floor and outer dry well regions.A series of sensitivity analyses were performed varying a combination of the initial suspended particle fraction and melt filtration inside the particle layer. Deceleration of the molten debris flow is significant due to the melt-particle bed frictional force and therefore the timing of molten debris running over the sump lids is faster when there is no particle layer. In this case, a large circulating flow is generated on the pedestal floor, and this flow promotes cooling and increases the viscosity. Influences of the initial suspended particle fraction on the melt viscosity become more pronounced in the peripheral region, and spreading behaviors are more susceptible to protrusions on the pedestal floor.