bluuebunny/crossref_metadata_2025 huggingface dataset:
Start‐ups' use of knowledge spillovers for product innovation: the influence of entrepreneurial ecosystems and virtual platforms
Authors: Cuvero Marco , Granados Maria L. , Pilkington Alan , Evans Richard
Published: November 2022

Entrepreneurial ecosystems have been explored widely in entrepreneurship, management and social sciences literature. The Knowledge Spillover Theory of Entrepreneurship (KSTE) aims to uncover the effects of information on start‐ups co‐located in diverse locations, such as urban areas, science and technology parks, incubators, and accelerator programs. Extant research has focused on how entrepreneurs launch start‐ups and develop patents over a 5–10 years timespan from a regional perspective. However, studies into the development processes of start‐ups and the creation of entrepreneurial ecosystems in physical and virtual environments in high‐tech start‐ups, are limited. As a result, this paper aims to identify the development processes undertaken by high‐tech entrepreneurs at the individual level and evaluate the absorption and implementation of knowledge in physical and virtual clusters within entrepreneurial ecosystems. A multiple case study of 32 start‐ups that have attended incubator and accelerator programs in London, United Kingdom, is presented. Semi‐structured interviews were conducted with Chief Executive Officers (CEOs) and Founders of start‐ups to propose the Model of Knowledge Spillovers and Entrepreneurial Ecosystems. The themes identified during interviews highlight the mechanisms employed by start‐ups to capture tacit and explicit knowledge spillovers. Theoretically, the findings of this study contribute to the KSTE by questioning the flexibility of entrepreneurs to access knowledge without the limitation of geographical proximity to sources of knowledge. Practically, our findings provide entrepreneurs with proven mechanisms required to capture tacit knowledge spillovers within entrepreneurial ecosystems and use virtual platforms to obtain explicit knowledge spillovers towards product innovation.
Plant‐soil research empowers students to dig deeper into restoration ecology
Authors: Valliere Justin M.
Published: November 2022

Training the next generation of applied ecologists is critical for combatting ongoing ecosystem degradation and meeting the rising demand for professionals in the ecological restoration economy. Despite growing interest, relatively few undergraduate programs are explicitly focused on restoration ecology. To adequately prepare students for future careers in restoration, educators should incorporate lessons on the science and practice of restoration into curricula of broader ecology courses. Given the interdisciplinary nature of restoration ecology, projects grounded in restoration science can be used by instructors to explore a broad range of topics. Course‐based research aimed at solving local restoration problems is one powerful way to enhance students' ecological literacy and professional development as well as promote diversity in the field. In this paper, I describe an initiative in which undergraduates in my ecology course conducted their own experiments evaluating the effects of soil amendments on the performance of native plant species that are targets for restoration on our campus nature preserve. Students worked in groups to independently design and execute experiments, analyze data, and communicate their results in formal reports and presentations. Student projects represent useful case studies that highlight the influence of soil conditions on restoration outcomes. Results of assessment surveys also illustrate the tremendous benefits of student‐led research on participants' scientific skills, learning experiences, and appreciation for applied science. A greater emphasis on restoration and inquiry‐based learning in undergraduate ecology courses will ensure students pursuing careers in ecological restoration have the training necessary to meet the complex challenges of such endeavors.
Smoking induces shifts in cellular composition and transcriptome within the bronchial mucus barrier
Authors: Rathnayake Senani N. H. , Ditz Benedikt , van Nijnatten Jos , Sadaf Tayyaba , Hansbro Philip M. , Brandsma Corry A. , Timens Wim , van Schadewijk Annemarie , Hiemstra Peter S. , ten Hacken Nick H. T. , Oliver Brian , Kerstjens Huib A. M. , van den Berge Maarten , Faiz Alen
Published: November 2022

Background and Objective

Smoking disturbs the bronchial‐mucus‐barrier. This study assesses the cellular composition and gene expression shifts of the bronchial‐mucus‐barrier with smoking to understand the mechanism of mucosal damage by cigarette smoke exposure. We explore whether single‐cell‐RNA‐sequencing (scRNA‐seq) based cellular deconvolution (CD) can predict cell‐type composition in RNA‐seq data.

Methods

RNA‐seq data of bronchial biopsies from three cohorts were analysed using CD. The cohorts included 56 participants with chronic obstructive pulmonary disease [COPD] (38 smokers; 18 ex‐smokers), 77 participants without COPD (40 never‐smokers; 37 smokers) and 16 participants who stopped smoking for 1 year (11 COPD and 5 non‐COPD‐smokers). Differential gene expression was used to investigate gene expression shifts. The CD‐derived goblet cell ratios were validated by correlating with staining‐derived goblet cell ratios from the COPD cohort. Statistics were done in the R software (false discovery rate p‐value < 0.05).

Results

Both CD methods indicate a shift in bronchial‐mucus‐barrier cell composition towards goblet cells in COPD and non‐COPD‐smokers compared to ex‐ and never‐smokers. It shows that the effect was reversible within a year of smoking cessation. A reduction of ciliated and basal cells was observed with current smoking, which resolved following smoking cessation. The expression of mucin and sodium channel (ENaC) genes, but not chloride channel genes, were altered in COPD and current smokers compared to never smokers or ex‐smokers. The goblet cell‐derived staining scores correlate with CD‐derived goblet cell ratios.

Conclusion

Smoking alters bronchial‐mucus‐barrier cell composition, transcriptome and increases mucus production. This effect is partly reversible within a year of smoking cessation. CD methodology can predict goblet‐cell percentages from RNA‐seq.
Boundary behavior of the solution to the linear Korteweg‐De Vries equation on the half line
Authors: Chatziafratis Andreas , Kamvissis Spyridon , Stratis Ioannis G.
Published: November 2022

In this paper, we consider the solution to the linear Korteweg‐De Vries (KdV) equation, both homogeneous and forced, on the quadrant via the unified transform method of Fokas and we provide a complete rigorous study of the integrals of the formula provided by the method, especially focusing on the explicit verification of the considered initial‐boundary‐value problems (IBVPs), with generic data, as well as on the uniform convergence of all its derivatives, as approaches the boundary of the quadrant, and their rapid decay as .
Prosodic variation of English in Dominica, Grenada, and Trinidad
Authors: Meer Philipp , Fuchs Robert , Deuber Dagmar , Lacoste Véronique , Hänsel Eva Canan
Published: November 2022

Varieties of English in the Caribbean have been claimed to have characteristic pitch patterns. However, there is little empirical research on prosodic aspects of English in the region. This paper provides a comparative phonetic analysis of several pitch parameters (pitch level, range, dynamism, rate of change, variability in rate of change, and tone rate) in English language data from Dominica, Grenada, and Trinidad that comprises read and spontaneous speech from 243 speakers. The results show that a wide pitch range and a high degree of variability in pitch, as mentioned in previous works, are not necessarily characteristic of English in the Caribbean overall, but that there are considerable cross‐territorial prosodic differences, with English in Trinidad showing more variability than in Dominica and Grenada, particularly among female speakers. Socioprosodic variation, largely specific to Trinidad, was also identified.
Effective Optimized Decomposition Algorithms for Solving Nonlinear Fractional Differential Equations
Authors: Laoubi Marwa , Odibat Zaid , Maayah Banan
Published: November 2022

In this paper, the optimized decomposition method, which was developed to solve integer-order differential equations, will be modified and extended to handle nonlinear fractional differential equations. Fractional derivatives will be considered in terms of Caputo sense. The suggested modifications design new optimized decompositions for the series solutions depending on linear approximations of the nonlinear equations. Two optimized decomposition algorithms have been introduced to obtain approximate solutions of broad classes of initial value problems (IVPs) consisting of nonlinear fractional ordinary differential equations (ODEs) and partial differential equations (PDEs). A comparative study was conducted between the proposed algorithms and the Adomian decomposition method (ADM) by means of some test illustration problems. The implemented numerical simulation results showed that the proposed algorithms give better accuracy and convergence, and reduce the complexity of computational work compared to the Adomian's approach. This confirms the belief that the optimized decomposition method will be used effectively and widely as a powerful tool in solving various fractional differential equations.
The Accelerated Transcatheter Heart Valve Testing Environment: Loading, Motion, and Fluid Dynamics
Authors: Ponnaluri Sailahari V. , Sacks Michael S. , Manning Keefe B.
Published: November 2022

Transcatheter aortic valve replacements (TAVRs) are an increasingly common treatment for aortic valve disease due to their minimally invasive delivery. As TAVR designs require thinner leaflets to facilitate catheter-based delivery, they experience greater leaflet operational stresses and potentially greater durability issues than conventional surgical valves. Yet, our understanding of TAVR durability remains largely unexplored. Currently, preclinical TAVR durability is evaluated within an ISO:5840 compliant accelerated wear tester (AWT) up to a required 200 × 106 cycles, corresponding to approximately five years in vivo. While AWTs use high cycle frequencies (10–20 Hz) to achieve realistic timeframes, the resulting valve loading behaviors and fluid dynamics are not representative of the in vivo environment and thus may not accurately predict failure mechanisms. Despite the importance of fatigue and failure predictions for replacement heart valves, surprisingly, little quantitative information exists on the dynamic AWT environment. To better understand this environment, we examined frequency and diastolic period effects for the first time using high-speed enface imaging and particle image velocimetry to quantify valve motion and flow, respectively, using a Durapulse™ AWT at frequencies of 10, 15, and 20 Hz. Regardless of operating condition, no waveform achieved a physiologically relevant transvalvular loading pressure, despite having an ISO compliant geometric orifice area (GOA) and waveform. General fluid mechanics were consistent with in vivo but the AWT geometry developed secondary flow structures, which could impact mechanical loading. Therefore, the nonphysiologic loading and variability induced by changes in operating condition must be carefully regulated to ensure physiologically relevant fatigue.
Traveling of Oscillating Vortices and Its Thermal Effects in a Bending Channel
Authors: Zhong Geyu , Zhang Chuanyu , Guo Xiaofeng , Yang Peng , Liu Yingwen
Published: November 2022

Driven by the periodical reverse of flow orientation, vortices in oscillatory flow induce a local high-speed and low-pressure flow region near the wall, which brings complex physical phenomena to viscous dissipation and heat transfer. This research focuses on the above-mentioned features by relating Spatio-temporal relationships between fluid dynamics and energy transmission. A two-dimensional oscillation model working in a thermoacoustic resonator is developed, considering heating and cooling processes in bending channels. We address oscillatory vortices' formation and transmission process in the bending channel. The acoustic streaming velocity field is obtained by postprocessing and proved to be the primary mechanism to induce spatial vortices in the vicinity of the entrance. The transferring vortices caused by the bending channel are like mini-pumps occupying fluid regions, which contribute to the local enhanced heat transfer performance and are influenced by the wall boundary conditions. The result also shows that skin friction in bending channels occupies about 10%–30% of total resistance, and the driving ratio is more sensitive to viscous dissipation than the wavy height of the bending channel. This study provides an approach to understanding the underlying mechanisms of heat transfer enhancement from hydrodynamics and inspiration to design compact heat exchangers employed in the oscillating flow.
Determination of the Optimum Operating Conditions and Geometrical Dimensions of the Plate Fin Heat Sinks Using Teaching-Learning-Based-Optimization Algorithm
Authors: Kuru Muhammet Nasıf
Published: November 2022

Electronic devices must be effectively cooled for long-term reliability and safe operation. It is essential to determine operating conditions and optimum dimensions of cooling devices in terms of device weight, space, cost, and sound limits. Plate fin heat sinks (PFHSs) are frequently used for cooling electronic devices. Optimum thermal designs of PFHSs are explored in this study using a teaching-learning-based-optimization (TLBO) algorithm where entropy generation (S˙gen) minimization, profit factor (J) maximization, base plate temperature excess (θb) minimization, total mass (mass) minimization, and total volume (volume) minimization are the objective functions of the constrained single-objective optimization problems. For further investigations of the entropy generation minimization method, three different optimization problems are also studied: minimization of thermal resistance (Rth), minimization of pressure drop (ΔP), and minimization of pumping power (W˙pump). Each optimization problem is subjected to a constraint, namely, temperature excess of base plate temperature (θb) should be lower than 10 K. Four optimization variables are considered which are the number of plate fins (N), freestream velocity (Vf), the thickness of the fin (tfin), and height of the fin (Hfin). Optimum configurations belonging to the different optimization problems are compared, and the effect of each optimization variable on the objective functions is discussed in detail. It is found that one can obtain optimum operating conditions and geometrical dimensions of the PFHSs according to the design objective, i.e., minimum mass requirement, space limitation, minimum base plate requirement, etc. As a result, the optimum designs of the studied cases are different which are superior to each other in terms of design targets.
Low Frequency Waterborne Sound Insulation Based on Sandwich Panels With Quasi-Zero-Stiffness Truss Core
Authors: Wang Dongwei , Zhang Quan , Hu Gengkai
Published: November 2022

Due to the negative correlation between pressure resistance and waterborne sound insulation, low-impedance soundproof materials can hardly work in deep water. Here, we propose a new mechanism to circumvent this problem by employing a sandwich panel with designed dynamics quasi-zero-stiffness (QZS) truss cores. The latticed cores are made of programable curved beams, whose shape is carefully designed to meet the demand of both high-pressure resistance and dynamics QZS. An analytical model is developed to evaluate sound transmission of such panel. It is shown that the low-frequency sound insulation performance of the customized panel increases with the hydrostatic pressure and reaches its maximum when the QZS state is triggered. The effective pressure range of the proposed sandwich panel can be further programed by stacking QZS beam lattices of different static load plateaus. The proposed design strategy stems solely from the structural geometry of the curved beams and is therefore materials-insensitive. The linear/inverse relationships between static loading feature and characteristic mechanical properties/geometrical parameters, and the stacking arrangement of lattice bring out the programability of the panel’s bearing capacity. The design strategy, together with the established database, provides a feasible approach for underwater sound insulation of equipment subjected to elevated pressures.
Minimizing Boundary Friction in Diesel Engines Piston Assembly: Testing the Rotating Liner Engine Prototype Under Load
Authors: Dardalis Dimitrios , Basu Amiyo K. , Hall Matt J. , Matthews Ronald D.
Published: November 2022

The Rotating Liner Engine (RLE) is a design concept where the cylinder liner of a heavy-duty Diesel engine rotates at about 2–4 m/s surface speed to eliminate the piston ring and skirt boundary friction near the top and bottom dead center. Based on prior testing results from our single cylinder RLE prototype (a converted four-cylinder Cummins ISB 3.9 Diesel) compared to a similar baseline, under idle conditions, the friction reduction is approximately 50 kPa (0.5 bar) in FMEP (friction mean effective pressure), which translates to about 40% for a complete engine. In this new set of experiments, we compare the RLE performance under load of up to about 7 bar IMEP (indicated mean effective pressure). It has been proven that the elimination of metallic contact between the compression rings and cylinder wall persists for up to 75 bar peak cylinder pressure and 1.5–2.3 m/s liner surface speed (283–426 rpm) for the 850–1280 rpm crankshaft speed. Additionally, the RLE FMEP is substantially reduced under load, which is a trend opposite to standard engines. Presumably, at idle the RLE cylinder and piston are cooler than the standard engine because the substantial heat dissipation by the metallic contact of the rings and skirts with the liner does not take place. Under load, however, the increased heat transfer from the combustion raises a piston and rotating cylinder temperatures, which reduces local lubricant viscosity and reduces mid-stroke viscous losses as well as rotating liner parasitic losses. Furthermore, based on higher speed baseline engine data, it appears that there is also a reduction in the hydrodynamic piston terms. The reason is attributed to the increased lubricant film thickness at mid-stroke, due to the combined effects of the liner rotation and the traditional wedge effects of the piston skirt and rings. This effect seems to more than compensate for the increase of the hydrodynamic parasitic friction of the liner rotation with engine speed (we currently have a constant 3:1 ratio of the crankshaft to liner speed). The combined fuel efficiency benefit is shown to exceed 10% for medium loads and speeds.
Modeling the Liquid Properties of E10 Gasoline for Application in Hydraulic and Combustion System Simulations at High Injection Pressures – Validation With Experimental Measurements
Authors: Tzanetakis Tom , Park Ji-Woong , Voice Alexander K.
Published: November 2022

Gasoline compression ignition (GCI) is an internal combustion engine technology that can improve the soot-NOx tradeoff and CO2 emissions of conventional diesel powertrains. GCI also offers a pathway to alleviate the operational and durability demands being placed on current lean aftertreatment systems for meeting upcoming criteria pollutant regulations. High-pressure fuel injection equipment is a key enabling subsystem for GCI and optimization along with the combustion, air and aftertreatment systems requires the use of simulation-based design tools like 1D hydraulic models or 3D-CFD. However, these tools require fuel property specifications to accurately capture the flow, spray, and combustion processes at conditions relevant to GCI. This work presents a surrogate formulation methodology that matches the entire measured chemical species listing of any gasoline as closely as possible and generates the required fuel properties over a specified range. It can be used when direct determination is not feasible or when properties are unknown at every condition of interest. Measurements of liquid density, viscosity, heat capacity and thermal conductivity were conducted on E10 certification gasoline from −20 to 150°C and 0–2500 bar (g) to validate the calculation methodology. Density did not exceed 1.6% difference with measured data, while heat capacity remained within 27%. Viscosity and thermal conductivity had maximum errors of 173% and 46%, respectively. This was due to the lack of appropriate pressure dependencies for these properties in the calculation methodology. The maximum error in modeled viscosity was reduced to 53% after employing a simple viscosity-pressure correlation for generic hydrocarbons.
Sooting Behavior of Commercial and Bio-Derived Butyl-Acetate/N-Heptane Blends in High-Pressure Spray Combustion Experiments
Authors: Stevenson Anna L. , Parker Allen J. , Reggeti Shawn A. , Agrawal Ajay K. , Bittle Joshua A.
Published: November 2022

The desire to use diesel blended with biofuels has accelerated in an effort to reduce reliance on non-renewable resources as well as reduce emissions from the heavy-duty portion of the transportation sector. Of particular interest are oxygenated compounds, notably esters, which have the potential to reduce the sooting tendency of diesel fuel. Butyl-acetate (BA) is one such ester with favorable properties as a fuel additive though perhaps not an obvious choice for a mixing controlled compression ignition engine due to its low cetane number. Despite this, if demonstrated to be able to reduced soot emissions when blended with diesel this blend candidate may be worth more study as a new bio-derived, low-energy, microbial fermentation process for production of BA shows promise for cost effective, high volume production. In this study, a constant-pressure flow chamber is utilized to observe fuel injection, mixing, ignition and combustion characteristics of commercial- and bio-BA blended with diesel surrogate n-heptane as a first study of its kind in a diesel-like fuel spray. Rainbow schlieren deflectometry, OH* chemiluminescence, and two-color pyrometry are utilized to quantify global parameters including ignition delay time, liquid length, vapor penetration, lift-off length, and soot mass. The results presented show that blending BA into n-heptane is effective at reducing soot emissions; moreover, the commercial-BA blend and the bio-BA blend are equally effective at reducing soot emissions. Future work will explore more test conditions, different blend ratios, and engine operation.
Simulation of Spray, Wall-Film, and Charge Preparation for Light-Duty, Cold-Start Applications
Authors: Edwards K. Dean
Published: November 2022

For modern, light-duty engine applications, the development of improved operating strategies to expedite catalyst heating during cold-start operation is essential for further reduction of emissions and meeting of future regulations. The development of such strategies would benefit from numerical modeling tools capable of accurate prediction of charge preparation, combustion, and emissions formation at cold-start conditions. Traditional development of simulation tools has primarily focused on standard engine operating conditions, and, as a result, these tools have difficulty accurately capturing extreme behavior during cold-start operation such as extensive wall wetting due to fuel-spray impingement on cold cylinder surfaces, late combustion phasing to increase exhaust enthalpy, and continued oxidation of reactants in the exhaust system. A major objective of the multi-national-laboratory Partnership to Advance Combustion Engines (PACE) consortium is the development and evaluation of new modeling approaches for cold-start operation. In this paper, we present recent progress in simulating charge preparation in a light-duty, multi-cylinder, gasoline engine during cold-start relevant conditions as defined by the U.S. DRIVE Advanced Combustion and Emission Control (ACEC) Tech Team cold-start protocols for catalyst heating. We focus study on fuel spray and spray-wall interactions resulting in extensive film formation due to cold cylinder walls. Simulation results are evaluated at steady-state, cold-start relevant operating conditions. Predictions for film formation and composition with conventional (baseline) models are compared to results with new simulation tools and approaches developed under PACE including the Corrective Distortion Spray Model developed by Sandia National Laboratories, which accounts for non-spherical droplet shapes, and a new spray-wall interaction model developed by Argonne National Laboratory, which accounts for multi-droplet, non-uniform impingement. The current study expands on past studies validating these new submodels with spray-chamber experimental measurements to examine the impact they have on full engine CFD simulations.
Predicting the Cetane Number, Sooting Tendency, and Energy Density of Terpene Fuel Additives
Authors: Kessler Travis , SubLaban Amina , Mack J. Hunter
Published: November 2022

Discovering renewable fuels and fuel additives is paramount in reducing carbon emissions from internal combustion engines. Terpenes, a group of compounds that can be synthesized from plant matter and microorganisms, have gained significant interest in recent years as promising candidates for fuels/additives. Terpenes are a diverse class of compounds that contain rings and methyl branches, resulting in high energy densities and optimal cold weather behavior. Their variation in bond order, carbon chains, and functional groups lead to varying degrees of soot formation and performance in existing engines. The present work leverages predictive models, namely artificial neural networks, to predict the cetane number (CN), sooting tendency (quantified with yield sooting index, YSI), and energy density (quantified with lower heating value, LHV) of terpenes and hydrogenated terpenes whose sooting propensities were previously determined through experimental means. Predicted sooting propensities of these terpenes are compared with experimental values, and predicted cetane numbers and energy densities are used to comment on the compounds’ ability to act as fuels/additives. Expected prediction errors for CN, YSI, and LHV, defined by blind test set median absolute error, are within 5.56 cetane units, 3.63 yield sooting index units, and 0.77 MJ/kg respectively. Additionally, the present work investigates a variety of correlation/dependence metrics for property-property relationships, furthering our understanding of how combustion-relevant properties are related.
Dynamic Modeling of the Supercritical Carbon Dioxide Simple Recuperated Brayton Cycle
Authors: Song Ping , Zhao Zhenxing , Dai Chunhui , Chen Lie , Yang Xiaohu , Wang Wei , Li Shaodan , Ma Can , Lao Xingsheng
Published: November 2022

With the development of the GEN-IV nuclear reactors in the 21st Century, as a substitute for the steam cycle, the supercritical carbon dioxide (SCO2) Brayton cycle has been widely used in a variety of power generation scenarios and has attracted widely attention from the scholars. However, the previous research mainly focused on the basic thermodynamics research, parameter optimizations and system design. Considering the load variability and control flexibility of the power generation system, the dynamic performance research of the SCO2 cycle is necessary. In the numerous layouts of SCO2 Brayton cycle, the SCO2 simple recuperated cycle stands out for its simple structure and high efficiency, which is also the main focus in this paper. In this paper, a dynamic model of SCO2 simple recuperated brayton cycle is developed with the Simulink software. The overall system includes a turbine (T), compressor (CM), regenerator (Re), intermediate heat exchanger (IHE), pre-cooler (PC), surge tank (ST), and heater. The models could be able to realize independent physical functions and be mathematically independent. The SCO2 recuperated cycle is then built with the developed models. Based on the simple recuperated system, the comparative calculation with the design value is carried out to verify the models and the results are very positive. Since the components are tightly coupled in the closed-loop cycle, the error of the main parameters for each component is relatively large. In the steady calculation, the maximum error of the component parameter is 7.72%, and the error of the cycle efficiency is about 1.45%. The results are very promising that the developed model has the ability to evaluate the thermal-hydraulic characteristics of the SCO2 Brayton circulation system.
Evaluation on Weldability of Nickel-Base Alloy Weld Materials With High Chromium Content
Authors: Katayama Yoshinori , Hayashi Takahiro , Tanaka Daiki , Takahashi Hidenori
Published: November 2022

Nickel (Ni)-base alloy 82 weld material is widely used for the primary reactor components of boiling water reactor (BWR). Although alloy 82 has shown excellent service performance for BWR application in terms of material reliability, several experiences have recently been reported regarding stress corrosion cracking (SCC) in welds associated with alloy 82. The present study aimed at enhancing SCC resistance of the weld material by developing and evaluating alloy 82 with increased chromium (Cr) content of 30%, 33% and 36%. Weld joint specimens were prepared by tungsten inert gas (TIG) welding with the prototyped wires of alloy 82 with increased Cr content. The mechanical properties and weldability were investigated using the weld joint specimens. For comparison, the conventional alloy 82 and alloy 52 were also tested. The mechanical properties of alloy 82 with increased Cr content were equal to or better than those of the conventional alloy 82. Varestraint test and bending test were carried out to determine the weldability. In the Varestraint test, the susceptibility to solidification cracking and ductility-dip cracking were evaluated. The temperature ranges of the ductility-dip cracking of the alloy 82 with increased Cr content was about the same as that of the conventional alloy 82. As a result of these tests, it was confirmed that the alloy 82 with increased Cr content has the same weldability as that of the conventional alloy 82 and was applicable for BWR components.
The Optimal Theta of Optimally Diffusive Coarse Mesh Finite Difference Method to Accelerate DGFEM Based SN
Authors: Kong Boran , Zhang Han , Zhu Kaijie , Hao Chen , Guo Jiong , Li Fu
Published: November 2022

Optimally diffusive coarse mesh finite difference (odCMFD) method is a recently developed acceleration method for neutron transport equation. Compared with the traditional CMFD, it adds an optimal theta on the diffusion coefficient. This new acceleration method achieves a higher convergence rate than the traditional CMFD and promises the convergence even in large optical thickness region. However, the optimal theta of odCMFD is determined by the Fourier analysis results of the 1D traditional SN. When applying the odCMFD to accelerate DGFEM based SN, this optimal theta is not always suitable. Therefore, it is necessary to find a new optimal theta for this new scheme. In this paper, a Fourier analysis of DGFEM based SN using odCMFD acceleration for k-eigenvalue neutron transport problem is conducted. Fourier analysis results show that when the number of inner iterations is higher than 10, the increment of the inner iterations has little impact on the spectral radius. Meanwhile, the order of the DGFEM based SN and the order of SN quadrature set have little impact on the spectral radius. The scattering ratio has great impact on the spectral radius, the decrement of scattering ratio increases the spectral radius. Set the number of inner iterations as 10, for different scattering ratio, an optimal theta of odCMFD and a polynomial fitting curve are obtained by Fourier analysis. Finally, numerical estimations of spectral radius are obtained by real 1D DGFEM based SN calculation with odCMFD acceleration. The experiment values fit well with the Fourier analysis theoretical results.
Research on Crack Resistance of Nuclear Grade Nickel-Based Alloy Welding Materials
Authors: Ao Ying , Xu Changzheng , He Guo , Lv Zhanpeng , Zhu Ping , Zhang Maolong , Zou Jiasheng
Published: November 2022

This paper mainly introduces the anti-crack performance of the nuclear grade nickel-based alloy welding materials produced by Baowu Special Metallurgy Co., Ltd. The research materials include welding wires (ERNiCrFe-7A), covered electrodes (ENiCrFe-7) and welding strips (EQNiCrFe-7A) used in PWR nuclear power plants. Evaluation of the anti-crack performance of the deposited metal is mainly carried out from the following three aspects: In order to study the thermal crack (crystal cracks) sensitivity of Baowu nickel-based alloy welding materials, the adjustable constraint test method is used and the results are compared with those of imported commercial welding materials; Based on STF (strain-to-fracture test) experimental method, the sensitivity of ductility dip cracking (DDC) of Baowu and imported nickel-based alloy welding materials is studied by thermal simulation equipment; The stress corrosion cracking (SCC) performance evaluation of Baowu welding materials is carried out by stress corrosion crack propagation experiment in simulated PWR primary water and compared with imported materials respectively. According to the above research, the crystal crack resistance, DDC resistance and SCC resistance of Baowu nickel-based alloy welding materials have reached the level of international high-level commercial welding material, which will further provide experimental data support for the engineering applicability and performance reliability of domestic nickel-based welding materials.
Classification on Electrical Parts Function Important to Safety for Nuclear Power Plants
Authors: Song Lei , He Zhijun
Published: November 2022

In the practice of engineering, classification of SSCs usually ends at equipment level, for example a control cabinet or switchgear based its safety function. However, classification of the parts is also necessary and meaningful. Although IAEA SSG-30 and TECDOC-1787 methodology provided is applicable to parts in equipment, safety function description of equipment usually has no direct relation to its parts, or in other word, has no strong connection. EPRI NP-5652 gives guideline on parts classification method in appendix B, but the guideline is at large.

To solve the problem, a practical classification method especially for parts is given in this paper. The method improved in this paper is based IAEA SSG-30 principle, EPRI NP-6895 and simplified FMEA. Firstly, this method take the equipment safety function classification and function description as starting; secondly, for every part in equipment, answering three main questions to determine whether the fixed part is safety related or not. Finally, the fixed part is classified as safety related or none safety related.

The practical classification method improved in this paper is not only applicable to electrical parts, but also applicable to the mechanical parts. When parent equipment’s function is not safety-related, this approach is also applicable, and then the analysis basement is equipment’s operation function.
Retracted: “Power Control System Design for Heat Pipe Cooled Reactor Based on Model Predictive Control” [2022 29th International Conference on Nuclear Engineering, Volume 15] Shenzhen, China and Virtual, Online, August 8–12, 2022, Conference Sponsors: Pressure Vessels and Piping Division, ISBN: 978-0-7918-8650-2, Copyright © 2022 by ASME. Paper No. ICONE29-89495, V015T16A014; 8 pages; doi: https://doi.org/10.1115/ICONE29-89495
Authors: ASME
Published: November 2022

This paper was removed at the author’s request on December 1, 2022.

Copyright © 2022 by ASME
Preliminary Design and Neutronics Analysis for a Medium Temperature Heat Pipe Cooled Reactor
Authors: Li Sina , Yan Binhuo , Tang Guojun , Peng Donghong , Lu Hongzhi
Published: November 2022

Traditional heat pipe cooled reactors have the characteristics of high core temperature and high fuel enrichment, which makes its development limited by several unfavorable factors, such as the limitation of high temperature materials and low burnup, etc. In this paper, a new heat pipe cooled reactor with a rated thermal power of 1.5MWt is proposed to address the problems of high operating temperature and high fuel enrichment. Low-enriched uranium is used as fuel. Mercury heat pipe is used instead of the traditional high temperature heat pipe in order to maintain a low operating temperature of around 350 °C. A superheated steam/water cycle with an efficiency of 33% can ensure the high thermal efficiency of the reactor. The Monte Carlo software MCNP5 is used to analyze the core physics characteristics, including the control rod worth, neutron energy spectrum, neutron distribution, temperature coefficient and core lifetime. A radial power peaking factor of 1.46 with controls inserted can satisfy the heat transfer requirements. A high control rod worth and high transient negative temperature coefficient can also ensure a high inherent safety of this reactor. The core lifetime is around 8 years.
Dependence Analysis of Nuclear Power Plant Operators Based on HRA
Authors: Xu Jie , Zhou Jianzhang , Liu Deyi , Wu Jian , Wang Zilong , Zhao Ming , Luo Yang , Chen Honghao
Published: November 2022

As an important part of probabilistic safety assessment (PSA), human reliability analysis (HRA) provides human error probabilities for assessing the risk of nuclear power plants (NPPs). Human reliability analysis (HRA) uses a systematic method to qualitatively and quantitatively assess the mechanism and probability of human error in order to assess the human contribution to the risks of NPPs. Dependence anslysis is an important part of HRA. Without dependency analysis, the result of human error probabilities may be over optimistic, which will lead to the underestimation of the safety risk level of the NPPs. Based on the feedback of human factor dependence from the experts review of level 1 PSA in NPPs. This paper summarized the technical insights of HRA dependence analysis, and used two dependence analysis methods to re-analyze the human factor dependence in the PSA model of nuclear power plant.

In this paper, starting from the problem of human dependence raised by experts in the peer assessment of first-level PSA in power operation, some technical insights on human dependence were summarized in the analysis and discussion of the existing HRA dependence method. Meanwhile, the human dependence of power PSA was analyzed again by SPAR-H method and NUREG-1921 dependence method.
Analysis of Thermal Stratification Effects in the Ring Headers of the Passive Residual Heat Removal System of NHR-200-II
Authors: Geng Yiwa , Liu Xiongbin
Published: November 2022

NHR-200-II is a small integral pressurized water reactor with a core thermal power of 200MW. Two parallel columns of passive residual heat removal (PRHR) system are connected to the two intermediate circuits of NHR-200-II to remove core decay heat in postulated accidents. It was confirmed by scaled experiments that the decay heat removal capacity of the PRHR system was severely deteriorated once the isolation valves for steam generator on the intermediate circuits failed to close. Thermal stratification effects in the ring headers of PRHR system played a significant role in the deterioration of PRHR capacity. A RELAP5 system model and a CFD model were developed for the PRHR system of NHR-200-II, in both models, we focused on the prediction of thermal stratification phenomena in the ring headers of PRHR. Both the case of normal PRHR scenarios (i.e. the SG branches were successfully isolated) and the case of isolation failure of the SG branches during PRHR startup were numerically simulated with the developed CFD and RELAP5 models. The numerical results from both CFD and RELAP5 models showed that the thermal stratification effects in normal PRHR scenarios can be neglected, however, both models gave similar conclusions that the thermal stratification effect was strong in the ring headers in case of isolation failure of the SG branches. Possible physical mechanism of thermal stratification in PRHR of NHR-200-II was explained depending on results of numerical simulations.
Research of Supercritical Carbon Dioxide Thermal Power System Based on Lead-Cooled Fast Reactor
Authors: Li Zhihui , Liu Chunyuan , Xing Mian , Zheng Gang , Wang Yu
Published: November 2022

The supercritical carbon dioxide (S-CO2) Brayton cycle with re-compression has the advantages of compact layout, simple structure, thermal high efficiency, clean working quality, its application in lead-cooled fast reactor power conversion system helps the miniaturization and modularization of the whole system. In addition, it is considered to be an effective solution to the problem of the recuperator point for the lead-cooled fast reactor power system. The Aspen plus software was applied in this paper to establish the mathematical model for supercritical carbon dioxide Brayton cycle with re-compression and the 1MWe lead-cooled fast reactor power system was calculated. The effects of several key factors such as the turbine inlet temperature, the turbine inlet pressure, the efficiency of the turbine, compressor and recuperator were analyzed. The results show that the turbine inlet pressure, the turbine inlet temperature and the turbine efficiency have remarkable effects on thermal efficiency of the system. Thermal efficiency of the system increases with the inlet pressure, inlet temperature and efficiency of the turbine increasing. The research results of this paper could provide important theoretical reference both for thermal cycle parameters for 1MWe lead-cooled fast reactor and system design of power cycle based on the lead-cooled fast reactor.
Effect of Surface Machining on Stress Corrosion Cracking Sensitivity of 304L and 316L Austenite Stainless Steel
Authors: Wu Huanchun , Meng Xinming , Han Yaolei , Zhang Yanwei , Peng Qunjia
Published: November 2022

304L/316L austenitic stainless steels (SSs) often used for main pipe of PWR nuclear power plant. Surface machining has a significant effect on microstructure and residual stress of SS, which further affects its stress corrosion cracking (SCC) sensitivity. The present study results show that, the SCC sensitivity of machined specimens increases significantly tested in 300 °C high temperature and high pressure water environment by the slow strain rate tensile test (SSRT). It increased from less than 10% of polished specimens to 20–30% of machined specimen for SCC sensitivity. It was found that the machined specimen showed as cleavage cracking, while the polished specimen was shown as ductile cracking with obviously fracture necking phenomenon. The mechanism of SCC of two kinds of SSs materials focused on the deformation layer of machined specimen was analysed, and the model of SCC initiation caused by nanocrystalline layer was established.
Optimization of Core Parameters Based on Artificial Neural Network Surrogate Model
Authors: Chen Shu , Ding Peng , Hu Shuowen , Xia Wenqing , Liu Min , Yu Fengwan , Li Wenhuai
Published: November 2022

The methodology of artificial intelligence (AI), particularly artificial neural network (ANN), would be in favor of nuclear energy system development. These ANN simulators may provide more efficient means than the traditional nuclear design codes, especially for the design of the key parameters, such as core geometry and layout, material composition.

In this paper, a neutronics calculation code SARAX and the corresponding multilayer perceptron (MLP) surrogate model were used as simulators for core parameters optimization of a reference lead based fast reactor. The pellet radius, enrichments and active height are the interested core parameters, and core burnup and power distribution are the target characteristics in the study. The training of structure and weight parameters in MLP network are based on about 5000 calculations of SARAX code. Test results of neural network show a good agreement between MLP surrogate model and SARAX code. The feasibility of the MLP surrogate model to be used in core parameters optimization was also discussed. Results showed that, the core surrogate model based on MLP could be quickly constructed and regulated, and be a more efficient simulators in a innovate reactor optimization.

The above work is completed in Sinan Platform, a multidisciplinary intelligent design platform developed by China Nuclear Power Technology Research Institute Co. Ltd.
Experimental Study on Aerosol Penetration Through Concrete Cracks Under Inertial Collision and Steam Condensation
Authors: Wang Shanpu , Li Yuxiang , He Liwen , Tong Lili , Cao Xuewu
Published: November 2022

Estimation of aerosol penetration through the cracked concrete wall with a submillimeter height has attracted more attention for radioactivity optimization evaluation of containment, which emphasizes the aerosol deposition inside the cracks without catastrophic destruction of containment. While, no deposition has been considered in current radiological assessments and the penetration of aerosol is simply assumed to be released as the leakage of gas. Therefore, the results of assessment are too conservation for the leakage of radioactive aerosol without considering any deposition.

In this work, an experimental facility is set up to study the penetration of particles through cracked concrete walls with different geometric dimensions. Titanium dioxide powder is chosen due to its density and nontoxicity. A sampling system is designed for the measurement of aerosol concentration under high temperature and containing condensable steam. One regular concrete crack in the shape of a straight rectangular slot and one irregular concrete crack with different streamwise tortuosities, τ, which is defined as the radio of the actual length of a crack pathway and the thickness of concrete structure, have been used in the tests of gas leakage and aerosol exposure. The height of cracks can be calculated from the consequences of gas leakage characteristic, based on the Suzuki’s flow model. Research results of aerosol exposure tests indicate that increasing the flow rate, particle diameter and tortuosity all can enhance the aerosol penetration, and micron particles cannot penetrate concrete cracks, compared with submicron particles. The aerosol penetration through the straight concrete crack is in good agreement with the prediction by the correlation proposed by Van De Vate, but no agreement is reached for the irregular crack with some tortuosity. Meantime, the effect of steam condensation on aerosol penetration is also been discussed preliminarily.