bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Safety-Enhanced Fast Reactor by Using Minor Actinide Bearing Internal Blanket
Authors: Fuchita Sho , Takeda Satoshi , Fujimura Koji , Takeda Toshikazu , Fujimata Kazuhiro
Published: October 2020

For a 750MWe sodium-cooled fast reactor core using MOX fuel, safety-enhancement measures have been studied to reduce the risk of core damage under unprotected loss of flow (ULOF) and unprotected transient overpower (UTOP) accidents.

As passive measures the followings are considered: 1) adoption of the axial heterogeneous core configuration with sodium plenum and Gas Expansion Modules (GEMs) to lower sodium void reactivity for ULOF, and 2) addition of minor actinides (MAs) as burnable absorber and fertile nuclides to the internal blanket in the inner core to reduce burnup reactivity for UTOP.

In this study, configurations of the safety-enhanced core were optimized based on sensitivity studies as follows.

Firstly, effects of 1) above on the sodium void reactivity were evaluated by changing the inner core height, B-10 content of the upper shield, GEMs, and standby position of the backup control rods, which are the dominant factors of core behavior in the event of ULOF.

Secondly, the effects of 2) above on the burnup reactivity were evaluated by changing the MA content in the internal blanket and the burnup period, which are the dominant factors of UTOP.

Finally, by utilizing sensitivity analysis results, the safety-enhanced core which satisfies the provisional design goals has been developed. This core has negative sodium void reactivity and burnup reactivity less than 1 $.
Development on Simulation Method for Two-Phase Flow in Large Diameter Pipes With 90 Degree Elbows
Authors: Komuro Yoshiteru , Kodama Atsushi , Kondo Yoshiyuki , Tanimoto Koichi , Hibiki Takashi
Published: October 2020

Two-phase flows are observed in various industrial plants and piping systems. Understanding two-phase flow behaviors such as flow patterns and unsteady void fraction in horizontal and vertical pipes are crucial in improving plant safety. Notably, the flow patterns observed in a large diameter pipe (approx. 4–6 in or larger) are significantly different from those observed in a medium diameter pipe. In a vertical large diameter pipe, no slug flow is observed due to the instantaneous slug bubble breakup caused by the surface instability. Besides, in a horizontal pipe, flow regime transition from stratification of liquid and gas to slug (plug) flow that induces unsteady flow should be taken into account. From this viewpoint, it is necessary to predict the flow regime in horizontal and vertical large diameter pipes with some elbows and to evaluate the unsteady flow regime. In this study, the simulation method based on the two-fluid model is developed. The two-fluid model is considered the most accurate model because the governing equations for mass, momentum, and energy transfer are formulated for each phase. When using the two-fluid model, some constitutive equations should be given in computing the momentum transfer between gas and liquid phases. In this study, several state-of-art constitutive equations of the bubble diameter, the interfacial drag force and non-drag forces such as the lift force and the bubble-bubble collision force, are implemented in the platform of ANSYS FLUENT. The developed simulation method is validated with visualization results and force from an air-water flow at the elbow of the piping system.
Heat Transfer for Supercritical Flow With TRACE
Authors: Spore Jay , Roth Glenn
Published: October 2020

Flow regimes at water pressures above the critical pressure are characterized as supercritical flow. Supercritical flows have no phase change. The heat transfer from the wall to the fluid is single phase (there is no boiling or condensation). Experimental data indicate that for conditions that involve supercritical single-phase heat transfer, the Dittus-Boelter heat transfer correlation can be in significant error.

A pseudo-critical temperature can be defined as a function of pressure for pressures that exceed the supercritical pressure. The pseudo-critical temperature is defined for heat transfer purposes as the temperature at which the specific heat peaks as the pressure is held constant. There is significant variation in fluid properties across the heat transfer boundary layer at temperatures near the pseudo-critical temperature. The large variation in properties is the reason for the failure of the Dittus-Boelter heat transfer correlation.

Comparisons to experimental data indicate that the Mokry heat transfer correlation is a significant improvement over the Dittus-Boelter heat transfer correlation for single phase supercritical heat transfer. The Mokry correlation was chosen to be included into TRACE.
Irradiation Induced Crosslinking in “Green” Polylactic-Acid (PLA) Polymers for Enhanced Strength and Elevated Temperature Applications
Authors: Jiang W. , Bakken A. , Taleyarkhan R. P.
Published: October 2020

This paper presents interdisciplinary (nuclear-mechanical-materials-chemical) engineering technology and results pertaining to use of ionization radiation for tailoring “green”, renewable corn-soy based amorphous and crystalline form polymers for use as low-to-high temperature adhesives. Both amorphous and crystalline form polymer forms of such the Polylactic-Acid (PLA) polymer were studied with and without photon irradiation, alongside with and without cross-linking agent. In order to study and enhance the high-temperature application of PLA as a novel, multi-purpose adhesive, small concentrations of the crosslinking agent triallyl isocyanurate (TAIC) were included into molten amorphous and semi-crystalline PLA cast as glue sticks, followed with Co-60 gamma-irradiation. Bond strength variations were studied in tensile mode at room temperature using the resulting adhesive in between two steel dowels (head-to-head bonded) as well as via shear strength testing at elevated temperatures (50–120°C) under a set pre-load of 222 N. It was found that gamma irradiated samples with TAIC exhibited noticeably improved bonding strength, and importantly, such strength can potentially prevail towards 100°C. These are exciting results which offer potential for application for building construction and safety enhancements especially under fires and similar accidents. Samples without TAIC exhibited significant loss of strength past 90°C. The full paper will discuss details of apparatus, modeling and simulation of irradiation dose delivery, testing protocols results, and future enhancements via hybrid neutron-photon-electron irradiation for utility in variety of industrial applications.
Experimental and Numerical Research on Steam Direct Contact Condensation Process in Automatic Depressurization System of AP1000
Authors: Zhang Yuhao , Feng Li , Qiu Zhimin , Fu Jingpin , Lu Daogang
Published: October 2020

In the third generation pressurized water reactor AP1000 plant, the Automatic Depressurization System (ADS) is one of the most important passive safety system. However, the steam Direct Contact Condensation (DCC) microscopic mechanisms are very complicated, which are not very clear yet. Moreover, the high-pressure and high-temperature experiment is very expensive to be conducted for many different test conditions. So in the present work, both the experimental and numerical methods are employed to investigate the steam DCC behavior. The steam DCC experimental bench has been built up, and the key parameters including the flow patterns and steam core temperature distributions are measured to provide validation data for the numerical results. In aspect of the numerical work, CFD simulation on the steam condensation is conducted. The heat and mass transfer process is simulated through the three-dimension commercial software FLUENT 16.0. Some of the key heat and mass transfer correlations are added by User Defined Function (UDF). The key parameters including the condensation steam fraction, temperature, and pressure, etc. are analyzed, which reflect the major heat transfer characteristics. According to the results, the expansion-compression-steam tail could be observed in both the numerical and experimental results. In essential, the steam fraction, temperature, and pressure distributions are determined by the equilibrium and transformation between the thermal dynamic energy and kinetic energy. The results provide working references for the practical ADS steam spraying condensation process in AP1000 reactor.
Corrosion Property of Container Using Hybrid Material for Thermal Decomposition Process of Sulfuric Acid
Authors: Ioka Ikuo , Kuriki Yoshiro , Iwatsuki Jin , Kawai Daisuke , Inagaki Yoshiyuki , Kubo Shinji , Inagaki Yoshiyuki
Published: October 2020

A thermochemical water-splitting iodine-sulfur process (IS process) is one of candidates for the large-scale production of hydrogen using heat from nuclear energy. Severe corrosive environment which is thermal decomposition of sulfuric acid exists in the IS process. To achieve an industrialization of massive hydrogen production system, one of the key factors is the development of structural materials for the severe corrosive environment. A hybrid material with the corrosion-resistance and the ductility had been made by a silicon powder plasma spraying and laser treatment. To confirm the applicability of the hybrid material as the structural material, corrosion tests of the hybrid materials had been performed in 95 mass% and 47 mass% boiling sulfuric acid. The corrosion resistance of specimen in the condition of 95 mass% boiling sulfuric acid had been excellent. This was attributed to the formation of SiO2 on the surface. To confirm the production characteristics as a container using the hybrid material, the container which has a welded part, a chamfer, a curved surface had been experimentally made. A configuration of the container had been 150mm inside diameter, 120mm in height and 6mm in thickness. The substrate of the container made of Hastelloy C276® superalloy had included TIG weld part. To improve the corrosion resistance of the container, pre-oxidation was performed at 800°C for 100 hours in air. There was no detachment of the plasma spraying and laser treated layer on the base metal and the welded part. The pre-oxidized container using hybrid technique was prepared for the corrosion test in boiling sulfuric acid to evaluate the characteristics of the container.
Study on the Liquid Seal Discharge Process in an Over-Pressurized Accident
Authors: Wu Dan , Deng Jian , Du Sijia , Qian Libo
Published: October 2020

In an over pressure accident, one or more pressurizer safety (or relief) valves will open due to the rapid pressure rise process. Once the safety (or relief) valves are open, the liquid seal will be discharged, and this will generate great discharge force to the downstream pipes. Multi-level protection is chosen using pressurizer safety (or relief) valves with different setpoint in most of Nuclear Power Plant, especially in the self-designed Generation-III Nuclear Power Plants. As the over pressure accident progresses, one or more safety (or relief) valves will be open. The downstream pipes will experience one or more times of impacts, which will influence the arrangement of the pipes. The whole discharge process is very complex, and the key influence factors are the pressure rise rate, safety (or relief) valve opening time, liquid seal temperature and volume, and the arrangement of the downstream discharge pipes. In present paper, liquid seal discharge process in an over pressure accident is studied. The pressure rise rate is so fast that three safety (or relief) valves will open one after another, which will generate three impacts on the downstream discharge pipes. It is found that for a specific design of Nuclear Power Plant, well design of the safety (or relief) valve setpoint is very important to the discharge force analysis results.
Uncertainty Quantification for the Development of Mechanistic Hydride Behavior Model for Spent Fuel Cladding Storage and Transportation
Authors: Duchnowski Edward M. , Seo Seokbin , Brown Nicholas R.
Published: October 2020

During operation of light water reactors hydrogen from the primary coolant is absorbed within the zirconium cladding and is able to migrate and redistribute within the cladding. The hydrogen in solid solution is able to precipitate, forming zirconium hydrides which results in a decrease of ductility of the cladding and ultimately an increase in likelihood of cladding failure, especially in conditions such as transport or storage of nuclear fuel rods. In collaboration with other universities, industries, and national laboratories the overarching goal of this project is to enhance the development for modeling hydride behavior to be implemented into the BISON fuel performance tool. The University of Tennessee-Knoxville (UTK) has been tasked with quantifying the uncertainty in the models developed within this project as well as quantifying the sensitivity to the most significant parameters of uncertainty.

The BISON fuel performance code has been shown to overpredict the total concentration of hydrogen at cold regions of a temperature profile, thus a sensitivity study was performed to quantify the impact that key diffusion parameters have on the local concentration of hydrogen at the cold end of a 1-D model subjected to an asymmetric temperature profile. It is shown within this document that the diffusion activation energy and the pre-exponential factor, values within the diffusion coefficient of hydrogen, have a large impact on the local concentration of hydrogen and their importance increases for an increase in annealing time.
Development of Ex-Vessel Phenomena Analysis Model for Multi-Scenario Simulation System, SPECTRA
Authors: Uchibori Akihiro , Aoyagi Mitsuhiro , Takata Takashi , Ohshima Hiroyuki
Published: October 2020

The simulation system named SPECTRA for a severe accident in sodium-cooled fast reactors has been developed. The SPECTRA computes in- and ex-vessel phenomena and evaluates various scenarios during the severe accident. This paper provides a newly developed computational models for the ex-vessel phenomena including gas and aerosol transport, sodium-concrete interaction, and sodium fire as a part of the SPECTRA. The base module computing thermal hydraulics behavior by a lumped mass model was verified through the analysis of a 2-cells ventilation problem. The computational result of the SPECTRA agreed with the theoretical solutions both in the case with and without temperature change. The sodium-concrete interaction model was verified through code to code comparison. The computational result showed that ablation of a concrete surface started after surface temperature reached to a certain value. The computed ablation depth almost completely agreed with the result by the CONTAIN-LMR code. The ex-vessel module was applied to the computation assuming sodium leak from a reactor vessel and a primary cooling loop. This computation demonstrated increase of temperature and pressure due to sodium-concrete interaction and sodium fire.
Study on the Interaction Between Safety-Related and Non Safety-Related Items in the Component Cooling Water System Room of the Qinshan Nuclear Power Plant in the Earthquake Condition
Authors: Zhang Liang , Xu Gang , Wang Yue , Chen Li , Zhou Shao Chong
Published: October 2020

Safety-related items in nuclear power plants are now generally placed separately from the non-safety-related items, but it was not strictly required before. Therefore, it is very important to study whether the non-safety-related items will affect the safety-related items when they are dropped down in an earthquake situation, which determines the safety of a nuclear power plant and its future life extension applications.

This research was based on the cooling water system room with the safety and non-safety related items installed together, as an example to study whether the non-safety-related items such as vent pipes and DN50 fire fighting pipes arranged above will damage the DN300 pipes and valves arranged below when earthquakes occur.

For the experiments, the relative positions of objects in the room was reproduced by 1: 1. The pressure-holding performance of the pipe was used as a criterion for the damage. The research results of the experiments show that when the 10-meter-long DN50 pipe was dropped from the position of 8 meters height and the 8-meter-long vent dropped from position of 3.6 meters height, they do not affect the integrity of the DN300 valve and pipe below. After the experiment, pressure drop in two hours for the pipe is less than 0.1%. The main body of the valve does not fail neither.

The numerical simulation study also shows that there is no failure phenomenon in the simulation as well. Compared with the test results, the impact acceleration and the vent deformation both have the same trend.
Two-Dimensional Full Core Analysis of IFBA-Coated TRISO Fuel Particles in Very High Temperature Reactors
Authors: Alrwashdeh Mohammad , Alameri Saeed A.
Published: October 2020

The Prismatic-core Advanced High Temperature Reactor (PAHTR) is a very high temperature reactor type which is one of promising reactor type technologies classified as Generation IV by the International Forum. The new technology designs are identified as being proliferation resistant, safe, economical, efficient, and long fuel cycle. In this paper, the continuous-energy Monte Carlo method is capable of capturing all of the necessary reactor physics parameters using high fidelity two dimensional model with Serpent Monte Carlo code, and applied for a large scale reactor core loaded with TRi-structural ISOtropic (TRISO) particle by taking into account the double heterogeneity effect. These analyses were performed for PAHTR reactor core that utilizes TRISO particles fuel embedded in graphite matrix by applying a new innovative idea of adding Integral Fuel Burnable Absorber (IFBA) as an additional coating layer with a designated thickness. Adding IFBA coating could lead to compressed excess reactivity at the Beginning of Cycle (BOC), and extended burnup cycle. The additional IFBA coating layer is placed in the outer surface of the fuel kernel and covered by the buffer layers that compose the TRISO fuel particle. Neutronic calculations were performed for both TRISO particle unit cell and for full core with homogenous distribution of IFBA coating.
Computational Study on the Spherical Laminar Flame Speed of Hydrogen-Air Mixtures
Authors: Trianti Nuri , Motegi Kosuke , Sugiyama Tomoyuki , Maruyama Yu
Published: October 2020

The computational fluid dynamics (CFD) have been developed to analyze the correlation equation for laminar flame speed of hydrogen-air mixtures. This analysis was carried out on the combustion of hydrogen-air mixtures performed at the spherical bomb experiment facility consists of a spherical vessel equipped (563 mm internal diameter). The facility has been designed and built at CNRS-ICARE laboratory. The simulation was carried out using the reactingFoam solver, one of a transient chemical reaction solver in OpenFOAM 5.0. The LaunderSharmaKE model was applied for turbulent flow. The interaction of the chemical reaction with the turbulent flow was taken into account using PaSR (Partial Stirred Reactor) model with 19 elementary reactions for the hydrogen combustion. The initial condition of spherical flame analysis was set so as to be consistent with those of the experiment. The position of the flame front was detected by the steep drop of hydrogen mass fraction in the spherical radii, and the flame propagation velocity was estimated from the time-position relationship. The analysis result showed the characteristic of spherical flame acceleration was qualitatively reproduced even though it has a discrepancy with the experiment. After validating the calculation of spherical experiments, a laminar burning velocity correlation is presented using the same boundary conditions with the variation of hydrogen concentration, temperature, and pressure. The calculation of laminar flame speed of hydrogen-air mixtures by reactingFoam use reference temperature Tref = 293 K and reference pressure Pref = 1 atm with validated in the range of hydrogen concentration 6–20%; range of temperature 293–493 K; and range of pressure 1–3 atm.
Experiment and Analysis on Isolation Condenser Simulator Using Pressurized Steam
Authors: Ono Kosuke , Yamamoto Yasunori , Mori Masayoshi , Takada Tetsuya
Published: October 2020

Isolation condensers (ICs) are important passive cooling systems in BWRs. After the Fukushima Daiichi Nuclear Power Station accident, concerns if the IC was able to restart with the inflow of hydrogen were arose. Because ICs lose heat removal ability when non-condensable gas inflow occurs, accurate evaluation of the effect is necessary. To develop analysis methods, as an initial stage, experiments and analyses considering only high-pressure steam and water were conducted. The experiment was done by an isolation condenser simulator which contains an accumulator with heaters inside, and a heat transfer tube. From the experiment, all steam was condensed at the heat transfer tube and the approximate position of complete condensation was confirmed from the temperature distribution and the observation. The experiment provided data such as temperature distribution, natural circulation flow rate, and pressure to compare with the analysis. The analyses were conducted for 4 cases of void fraction values at the heat transfer tube inlet and found that it has a high sensitivity to condensation. The reason is estimated to be the difference in inflow velocity that strongly depends on the void fraction even if the mass flow rate is constant. And the initial condition of the liquid film also affected condensation process. Heat removal at the section before the heat transfer tube should be considered to adjust void fraction at the inlet of heat transfer tube.
Transient Analysis of Dedicated Pressure Relief Valve Under High-Pressure Condition in Severe Accident for Tianwan 56 Nuclear Power Plant
Authors: Xu Youyou , Deng Jian , Wang Xiaoji , Wu Lingjun , Zhang Ming , Qian Libo , Cai Rong , Zhong Lei , Du Zhengyu
Published: October 2020

In the management of severe accident of nuclear reactor, the pressure relief of reactor coolant system (RCS) is an important mitigation measure to prevent high pressure core melt (HPCM). In the safety system improvement of Tianwan56 nuclear power plant, the optimization measure of adding the dedicated pressure relief valve (DPRV) for severe accident were adopted. This improvement allows the reactor to release the pressure of RCS before the reactor vessel being damaged to mitigate the consequence of reactor melt accident under high-pressure condition. Based on the analysis of severe accident sequences, the total loss of feed water accident is confirmed to cover the various severe accident consequences which may lead to HPCM accident. This paper studied the transient characteristics of total loss of feed water accident sequences, and the factors such as valve opening delay on the operating temperature of the valve were researched. Finally, the representative and envelope operating condition of DPRV under severe accident was clarified. Besides, the temperature curve of fluid passing through the valve and the maximum temperature the valve experienced were obtained. This research provides the valuable and indispensable basis to the operability and integrity analysis of DPRV in severe accident.
Numerical Validation of AQUA-SF in SNL T3 Sodium Spray Fire Experiment
Authors: Sonehara Masateru , Aoyagi Mitsuhiro , Uchibori Akihiro , Takata Takashi , Ohshima Hiroyuki , Clark Andrew J. , Louie David
Published: October 2020

In order to investigate the effect of sodium combustion, Sandia National Laboratories (SNL) and Japan Atomic Energy Agency (JAEA) have exchanged information of sodium combustion modeling and related experimental data in the framework of Civil Nuclear Energy Research and Development Working Group (CNWG). This collaboration includes a benchmark analysis of the SNL Surtsey spray combustion experiment (SNL T3 experiments) using AQUA-SF and SPHINCS in JAEA. In this paper, investigation into multi-dimensional effect and best estimate for T3 experiment with AQUA-SF are conducted as validation and verification of the code. A spray combustion is characterized by formation of sodium droplet cloud due to pressure difference and their spreading with combustion. Therefore, the combustion phenomenon will be much affected by spatial distributions of parameters such as gas temperature, gas velocity and oxygen concentration.

As a best estimate analysis, the spray burning duration is adjusted in the computation in order to take into account the temporary suppression of the spray combustion observed in the experiment. Furthermore, droplet size of SPHINCS and AQUA-SF are optimized to represent the T3 experimental results. For the best estimate in AQUA-SF, sodium droplet size needs to be set larger than SPHINCS in order to decrease the surface area and suppress the spray burning rate. These adjustment leads to more precise representation of the measurements in T3 experiment.
On Effects of Temperature Boundary Conditions on Heat Transfer in Turbulent Low-Prandtl-Number Flows
Authors: Otic Ivan
Published: October 2020

One important issue in understanding and modeling of turbulent heat transfer is the behavior of fluctuating temperature close to the wall. Common engineering computational approach assumes constant heat flux boundary condition on heated walls. In the present paper constant heat flux boundary condition was assumed and effects of temperature fluctuations are investigated using large eddy simulations (LES) approach. A series of large eddy simulations for two geometries is performed: First, forced convection in channels and second, forced convection over a backward facing step. LES simulation data is statistically analyzed and compared with results of direct numerical simulations (DNS) from the literature which apply three cases of heat flux boundary conditions: 1. ideal heat flux boundary condition, 2. non-ideal heat flux boundary condition, 3. conjugate heat transfer boundary condition. For low Prandtl number flows LES results show that, despite very good agreement for velocities and mean temperature, predictions of temperature fluctuations may have strong deficiencies if simplified boundary conditions are applied.
Representativity Analysis Applied to TREAT Water Loop LOCA Experiment Design
Authors: Epiney Aaron S. , Woolstenhulme Nicolas
Published: October 2020

The Transient Reactor Test (TREAT) Facility at Idaho National Laboratory (INL) started testing new fuels and reactor technologies once again in 2018 and new experiments and tests are currently being designed like for example the water loop “TREAT Water Environment Recirculating Loop” (TWERL). During the design of such experiments, the designer must assess how close the experiment reproduces the physics (and other important phenomena) happening during a transient of interest compared to the full-size reactor the experiment attempts representing. Traditionally, to assess this “representativity” of the experiment, scaling theory involving expert judgment is needed. This paper presents a step towards a systematic modeling and simulation (M&S) informed methodology for experiment design. The new methodology compares a model of the full system and a model of the mock-up facility that are subject to the same perturbations. In this way, the “overlap” of the perturbed experiment and full-size facility model outputs can be analyzed and the “representativity” of the experiment determined. The paper presents a RELAP5-3D analysis, where TWERL LOCA calculations are compared to prototypic PWR LOCA calculations with respect to representativity. To inform the design of the TWERL experiments, i.e. to find the most “representative” configuration for the TWERL loop, different design parameters for TWERL have been optimized in the study.
Experimental Study of the Effect of Hydrogen Inflow on Passive Core Cooling System With Natural Circulation Flow
Authors: Yamamoto Yasunori , Mori Masayoshi , Ono Kosuke , Takada Tetsuya
Published: October 2020

Isolation Condenser (IC) is one of the passive core cooling systems with natural circulation flow, which is effective for safety measures against station black out. Once core uncover occurs, hydrogen generated in the core affects operating condition of ICs. To use ICs as an important safety measure not only for transient conditions but also for accident conditions, robustness of ICs against hydrogen inflow must be understood well. In this study, experiments with high pressure steam were conducted using experimental setup simulating IC, where helium was injected to simulate hydrogen effects. When the pressure in an accumulator increased high enough, natural circulation flow generated in the experimental loop. After the long-term operation, the pressure and the natural circulation flow rate achieved nearly constant. The pressure at quasi-steady state increased with increasing the helium injection amount. The pressure difference in a section including outlet side of a vertical pipe was slightly increased when helium was injected which may have indicated that the helium accumulated in the section and caused increment of the pressure loss. The startup pressure of the IC simulator also increased when helium was injected, where the driving force by the water head difference also decreased. Though long-term operations were performed after helium injection, the effect of injected helium on operating conditions of the IC remained for quasi-steady state conditions.
Experimental Study on Multi-Channel Jets in Plate Assembly Under Blockage Condition
Authors: Huijian Huang , Peng Wang , Dongyang Li , Tan Sichao
Published: October 2020

In the nuclear field, the reactor using plate fuel assembly forms multiple jets at exit. So, it’s meaningful to study multiple jets to learn the behavior of the coolant when it leaves the core. This paper uses PIV technology to study the flow characteristics of 9 jets at low Reynolds number. Firstly, the velocity field reveals that the pressure outside the jet is greater than the inside of the jet, which causes the jet to deflect and converge inward at z/w = 0–8. Then, the velocity field with different Re number is analyzed in the center plane, and find that the flow distribution is similar. Then, a detailed analysis is performed on the jet under specific conditions, and the merge point is discussed in the paper. At the same time, the first-order velocity tensor are also calculated in this paper. In addition, this article also analyzes the jet flow field after the central narrow channel was blocked. In this experiment, a plug was used to block the No. 5 jet by 1/3. And the flow redistribution is discussed in this case. The methods of flow calculation using PIV technology is established and compared with the real number of flowmeters, it’s found that the calculation method is rather accurate. On the other hand, the experiment find that the distribution of flow in each channel is not uniform, and the blocking condition make an increase in the flow of edge channels, which leads to the decreasing of flow in the blocked adjacent channel.
Numerical Analysis of Nuclear Facility Reinforced Concrete Wall and Roof Slab Behavior Under Close-in Explosions
Authors: Rongpeng Li , Yumin Li , Chunguang Sui , Di Jiang
Published: October 2020

With the change of anti-terrorism situation, civil unmanned aerial vehicles carrying small equivalent of explosives may cause damage to the reinforced concrete wall or roof of nuclear facilities at close range. Existing research has mostly focused on the overall damage caused by large equivalent explosives at medium and long distances. In this paper, the air overpressure peak curve and behavior of reinforced concrete slabs under small equivalent TNT close-in explosion conditions are calculated by numerical simulation methods and compared with empirical formulas and experimental results in the literature to verify. Furthermore, the numerical simulation method was used to evaluate the resistance of 300mm thick reinforced concrete slabs to close-in impacts of different mass TNT at a standoff distance of 0.4m.
Context effects on phoneme categorization in children with dyslexia
Authors: O'Brien Gabrielle E. , Gijbels Liesbeth , Yeatman Jason D.
Published: October 2020

Research shows that, on average, children with dyslexia behave less categorically in phoneme categorization tasks. This study investigates three subtle ways that struggling readers may perform differently than their typically developing peers in this experimental context: sensitivity to the frequency distribution from which speech tokens are drawn, bias induced by previous stimulus presentations, and fatigue during the course of the task. We replicate findings that reading skill is related to categorical labeling, but we do not find evidence that sensitivity to the stimulus frequency distribution, the influence of previous stimulus presentations, and a measure of task engagement differs in children with dyslexia. It is, therefore, unlikely that the reliable relationship between reading skill and categorical labeling is attributable to artifacts of the task design, abnormal neural encoding, or executive function. Rather, categorical labeling may index a general feature of linguistic development whose causal relationship to literacy remains to be ascertained.
A Comparison of Clinical Spinal Mobility Measures to Experimentally Derived Lumbar Spine Passive Stiffness
Authors: Tennant Liana M. , Nelson-Wong Erika , Kuest Joshua , Lawrence Gabriel , Levesque Kristen , Owens David , Prisby Jeremy , Spivey Sarah , Albin Stephanie R. , Jagger Kristen , Barrett Jeff M. , Wong James D. , Callaghan Jack P.
Published: October 2020

Spinal stiffness and mobility assessments vary between clinical and research settings, potentially hindering the understanding and treatment of low back pain. A total of 71 healthy participants were evaluated using 2 clinical assessments (posteroanterior spring and passive intervertebral motion) and 2 quantitative measures: lumped mechanical stiffness of the lumbar spine and local tissue stiffness (lumbar erector spinae and supraspinous ligament) measured via myotonometry. The authors hypothesized that clinical, mechanical, and local tissue measures would be correlated, that clinical tests would not alter mechanical stiffness, and that males would demonstrate greater lumbar stiffness than females. Clinical, lumped mechanical, and tissue stiffness were not correlated; however, gradings from the posteroanterior spring and passive intervertebral motion tests were positively correlated with each other. Clinical assessments had no effect on lumped mechanical stiffness. The males had greater lumped mechanical and lumbar erector spinae stiffness compared with the females. The lack of correlation between clinical, tissue, and lumped mechanical measures of spinal stiffness indicates that the use of the term “stiffness” by clinicians may require reevaluation; clinicians should be confident that they are not altering mechanical stiffness of the spine through segmental mobility assessments; and greater resting lumbar erector stiffness in males suggests that sex should be considered in the assessment and treatment of the low back.
Measuring Physical Activity Levels in People With Mild Cognitive Impairment or Mild Dementia
Authors: van der Wardt Veronika , Hancox Jennie E. , Burgon Clare , Bajwa Rupinder , Goldberg Sarah , Harwood Rowan H.
Published: October 2020

Measuring physical activity (PA) in people with mild cognitive impairment or dementia can be difficult. The aim was to investigate the validity and acceptability of three different PA measurement methods. The mixed-method analysis included 49 participants with mild cognitive impairment or dementia, who completed a daily calendar recording PA, the International Physical Activity Questionnaire, and the Longitudinal Aging Study Amsterdam PA Questionnaire, and those who wore a Misfit Shine accelerometer. The quantitative analysis showed equal completion rates for the International Physical Activity Questionnaire and the accelerometer but a lower completion rate for the calendar. Correlations between outcome measures were moderate or strong. The qualitative analysis indicated that all measures were acceptable, though some participants required help to complete the calendars or fasten the accelerometers. The study supported the validity of these methods for people with mild cognitive impairment and mild dementia. Using accelerometers and completing calendars might increase the motivation to be active for some people.
Embodiment in Active Sport Tourism: An Autophenomenography of the Tour de France Alpine “Cols”
Authors: Lamont Matthew
Published: October 2020

Existing conceptualizations of active sport tourism lack an empirical foundation in explaining the processes of embodiment through which active sport tourists engage with destination space. Adopting an autophenomenographic perspective, this paper explores embodiment in the context of a cycling tourism experience encompassing six iconic mountain passes within the French Alps synonymous with the Tour de France. Qualitative data draw attention to kinaesthetic and visceral sensations arising through multisensory feedback, along with affective responses produced as the body traverses venerated sport landscapes. This research highlights mind–body processes that shape mobile, active sport tourism experiences and provides an empirical and conceptual foundation to inform future studies of embodiment in active sport tourism.
Inhibition of Coronavirus Entry
In Vitro
and
Ex Vivo
by a Lipid-Conjugated Peptide Derived from the SARS-CoV-2 Spike Glycoprotein HRC Domain
Authors: Outlaw Victor K. , Bovier Francesca T. , Mears Megan C. , Cajimat Maria N. , Zhu Yun , Lin Michelle J. , Addetia Amin , Lieberman Nicole A. P. , Peddu Vikas , Xie Xuping , Shi Pei-Yong , Greninger Alexander L. , Gellman Samuel H. , Bente Dennis A. , Moscona Anne , Porotto Matteo
Published: October 2020

SARS-CoV-2, the causative agent of COVID-19, continues to spread globally, placing strain on health care systems and resulting in rapidly increasing numbers of cases and mortalities. Despite the growing need for medical intervention, no FDA-approved vaccines are yet available, and treatment has been limited to supportive therapy for the alleviation of symptoms. Entry inhibitors could fill the important role of preventing initial infection and preventing spread. Here, we describe the design, synthesis, and evaluation of a lipopeptide that is derived from the HRC domain of the SARS-CoV-2 S glycoprotein that potently inhibits fusion mediated by SARS-CoV-2 S glycoprotein and blocks infection by live SARS-CoV-2 in both cell monolayers (
in vitro
) and human airway tissues (
ex vivo
). Our results highlight the SARS-CoV-2 HRC-derived lipopeptide as a promising therapeutic candidate for SARS-CoV-2 infections.
Prevalence and risk factors for back pain in sports: a systematic review with meta-analysis
Authors: Wilson Fiona , Ardern Clare L , Hartvigsen Jan , Dane Kathryn , Trompeter Katharina , Trease Larissa , Vinther Anders , Gissane Conor , McDonnell Sarah-Jane , Caneiro JP , Newlands Craig , Wilkie Kellie , Mockler David , Thornton Jane S
Published: October 2020

Objectives

We aimed to determine the prevalence of low back pain (LBP) in sport, and what risk factors were associated with LBP in athletes.

Design

Systematic review with meta-analysis.

Data sources

Literature searches from database inception to June 2019 in Medline, Embase, Cumulated Index to Nursing and Allied Health Literature (CINAHL), Web of Science and Scopus, supplemented by grey literature searching.

Eligibility criteria

Studies evaluating prevalence of LBP in adult athletes across all sports.

Results

Eighty-six studies were included (30 732, range 20–5958, participants), of which 45 were of ‘high’ quality. Definitions of LBP varied widely, and in 17 studies, no definition was provided. High-quality studies were pooled and the mean point prevalence across six studies was 42%; range 18%–80% (95% CI 27% to 58%, I2=97%). Lifetime prevalence across 13 studies was 63%; range 36%–88% (95% CI 51% to 74%, I2=99%). Twelve-month LBP prevalence from 22 studies was 51%; range 12%–94% (95% CI 41% to 61%, I2=98%). Comparison across sports was limited by participant numbers, study quality and methodologies, and varying LBP definitions. Risk factors for LBP included history of a previous episode with a pooled OR of 3.5; range 1.6–4.0 (95% CI 1.9 to 6.4). Statistically significant associations were reported for high training volume, periods of load increase and years of exposure to the sport.

Conclusion

LBP in sport is common but estimates vary. Current evidence is insufficient to identify which sports are at highest risk. A previous episode of LBP, high training volume, periods of load increase and years of exposure are common risk factors.
Gamut of Cardiac Manifestations and Complications of COVID-19: A Contemporary Review
Authors: Cruz Rodriguez Jose Benjamin , Lange Richard A , Mukherjee Debabrata
Published: October 2020

COVID-19 has posed an extraordinary burden on health and the economy worldwide. Patients with cardiovascular diseases are more likely to have severe illness due to COVID-19 and are at increased risk for complications and mortality. We performed a narrative literature review to assess the burden of COVID-19 and cardiovascular morbidity and mortality. Myocardial injury has been reported in 20%–30% of patients hospitalized due to COVID-19 and is associated with a worse prognosis and high mortality (~50%–60%). Proposed mechanisms of myocardial injury include inflammation within the myocardium (due to direct viral infection or cytokine storm), endotheliitis, coronary vasculitis, myocarditis, demand ischemia, plaque destabilization and right ventricular failure. The right ventricle is particularly vulnerable to injury and failure in COVID-19-infected patients, given the hypoxic pulmonary vasoconstriction, pulmonary microthrombi or pulmonary embolism. Echocardiography is an effective and accessible tool to evaluate left and right ventricular functions and risk stratify patients with COVID-19 infection. Cardiac MRI has detected and characterized myocardial injury, with changes compatible with other inflammatory cardiomyopathies. The long-term consequences of these inflammatory changes are unknown, but accumulating data will provide insight regarding the longitudinal impact of COVID-19 infection on cardiovascular morbidity and mortality.
Cost-effectiveness of endovascular thrombectomy in patients with acute stroke and M2 occlusion
Authors: Khunte Mihir , Wu Xiao , Payabvash Sam , Zhu Chengcheng , Matouk Charles , Schindler Joseph , Sanelli Pina , Gandhi Dheeraj , Malhotra Ajay
Published: October 2020

Background

The cost-effectiveness of endovascular thrombectomy (EVT) in patients with acute ischemic stroke due to M2 branch occlusion remains uncertain.

Objective

To evaluate the cost-effectiveness of EVT compared with medical management in patients with acute stroke presenting with M2 occlusion using a decision-analytic model.

Methods

A decision-analytic study was performed with Markov modeling to estimate the lifetime quality-adjusted life years and associated costs of EVT-treated patients compared with no-EVT/medical management. The study was performed over a lifetime horizon with a societal perspective in the Unites States setting. Base case, one-way, two-way, and probabilistic sensitivity analyses were performed.

Results

EVT was the long-term cost-effective strategy in 93.37% of the iterations in the probabilistic sensitivity analysis, and resulted in difference in health benefit of 1.66 QALYs in the 65-year-old age groups, equivalent to 606 days in perfect health. Varying the outcomes after both strategies shows that EVT was more cost-effective when the probability of good outcome after EVT was only 4–6% higher relative to medical management in clinically likely scenarios. EVT remained cost-effective even when its cost exceeded US$200 000 (threshold was US$209 111). EVT was even more cost-effective for 55-year-olds than for 65-year-old patients.

Conclusion

Our study suggests that EVT is cost-effective for treatment of acute M2 branch occlusions. Faster and improved reperfusion techniques would increase the relative cost-effectiveness of EVT even further in these patients.
Ultrasound-guided subparaneural popliteal sciatic nerve block: there is more to it than meets the eyes
Authors: Karmakar Manoj Kumar , Reina Miguel A , Sivakumar Ranjith Kumar , Areeruk Pornpatra , Pakpirom Jatuporn , Sala-Blanch Xavier
Published: October 2020

The popliteal sciatic nerve block is routinely used for anesthesia and analgesia during foot and ankle surgery. This article reviews our current understanding of the anatomy of the sciatic nerve and discusses how fascial tissue layers associated with the nerve may affect block outcomes . The anatomy of the sciatic nerve is more complex than previously described. The tibial and common peroneal nerves within the sciatic nerve trunk appear to be centrally separated by the Compton-Cruveilhier septum and encompassed by their own paraneural sheaths. This unique internal architecture of the sciatic nerve appears to promote proximal spread of local anesthetic to the internal aspect of the sciatic nerve trunk after a subparaneural injection at or below the divergence of the tibial and common peroneal nerves.
Susceptible-infected-spreading-based network embedding in static and temporal networks
Authors: Zhan Xiu-Xiu , Li Ziyu , Masuda Naoki , Holme Petter , Wang Huijuan
Published: October 2020

Link prediction can be used to extract missing information, identify spurious interactions as well as forecast network evolution. Network embedding is a methodology to assign coordinates to nodes in a low-dimensional vector space. By embedding nodes into vectors, the link prediction problem can be converted into a similarity comparison task. Nodes with similar embedding vectors are more likely to be connected. Classic network embedding algorithms are random-walk-based. They sample trajectory paths via random walks and generate node pairs from the trajectory paths. The node pair set is further used as the input for a Skip-Gram model, a representative language model that embeds nodes (which are regarded as words) into vectors. In the present study, we propose to replace random walk processes by a spreading process, namely the susceptible-infected (SI) model, to sample paths. Specifically, we propose two susceptible-infected-spreading-based algorithms, i.e.,Susceptible-InfectedNetworkEmbedding (SINE) on static networks andTemporalSusceptible-InfectedNetworkEmbedding (TSINE) on temporal networks. The performance of our algorithms is evaluated by the missing link prediction task in comparison with state-of-the-art static and temporal network embedding algorithms. Results show thatSINEandTSINEoutperform the baselines across all six empirical datasets. We further find that the performance ofSINEis mostly better thanTSINE, suggesting that temporal information does not necessarily improve the embedding for missing link prediction. Moreover, we study the effect of the sampling size, quantified as the total length of the trajectory paths, on the performance of the embedding algorithms. The better performance ofSINEandTSINErequires a smaller sampling size in comparison with the baseline algorithms. Hence, SI-spreading-based embedding tends to be more applicable to large-scale networks.