bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a Lead-Free Bronze Bearing Alloy With Improved Conformability and Seizure Performance
Authors: Harvey Jennifer , Stearns John , Merchant Jack 
Published: November 2022

Abstract
Material selection for off-highway heavy duty engine bearing applications is becoming more complex as there is a growing requirement to replace the traditionally utilized copper-lead based lining alloys due to adverse health and environmental concerns surrounding heavy metals. Although upcoming legislation is increasing the drive to find alternative lead-free solutions these have not been well adopted for all applications as there are limited products available that are matched to the excellent performance of leaded materials in tolerance to debris, ability to conform and prevention of seizure events.
This paper details the development of a new lead-free bronze alloy with a focus on improvements in conformability and seizure resistance compared to current lead-free materials. A new alloy composition is introduced which contains bismuth soft phase with optimized tin content which when combined with a lead-free electroplated overlay presents a robust material for applications where seizure performance might be a concern.
The present development provides a suitable product that will enable the future-proofing of off-highway heavy duty applications and offers a solution to inevitable future restrictions surrounding leaded materials. Results from bespoke rig testing and engine testing are detailed that support the material development.
Investigation of Flow and Flame Propagation in a Spark Ignition Direct Injection Engine Using Particle Image Velocimetry
Authors: Shen Li , Willman Christopher , Stone Richard 
Published: November 2022

Abstract
Variations in the in-cylinder flow before and during combustion influence the propagation of the flame in spark ignition direct injection (SIDI) engines, which leads to variations in combustion between engine cycles. Accommodating such cycle-to-cycle variation in production engines requires design compromises that may reduce efficiency. The in-cylinder flow and flame evolve rapidly during combustion, and due to the existence of cyclic variation, the flame propagation in individual cycles cannot be replicated by taking measurements at different timings over different cycles, hence crank-angle-resolved measurements in the same cycle are needed. However, such high-speed flow and flame measurements usually require combining multiple laser-based diagnostic techniques, which can be costly due to the need for multiple lasers with high repetition rates at different wavelengths. In this work, the crank-angle-resolved flow velocity and the flame propagation on a swirl plane in an optically accessible SIDI engine were simultaneously measured by a single laser-based diagnostic technique — high-speed planar particle image velocimetry (PIV). In-plane flame boundaries were inferred from the absence of PIV seeding oil droplets in the burned gas regions. Line-of-sight flame images from two orthogonal views were recorded synchronously with the PIV data in order to validate the in-plane flame boundaries derived from the PIV data. The impact of the neighbouring flow on the evolution of the flame boundaries over crank angles is examined.
Injection Strategies for POMDME- and Diesel-Natural Gas Dual Fuel Engines
Authors: Hariharan Deivanayagam , Krishnan Sundar Rajan , Srinivasan Kalyan Kumar 
Published: November 2022

Abstract
Conventional dual-fuel combustion (DFC) has been studied for decades due to its ability to produce high fuel conversion efficiency and its potential to defeat the well-known diesel NOx-PM trade-off. In DFC, a low-reactivity fuel (LRF) such as natural gas is premixed with air and ignited with the help of a high-reactivity fuel (HRF) such as diesel. In DFC, along with its low PM emissions, NOx emissions are reduced significantly by advancing the start of injection (SOI) to earlier than 320 CAD (40 degrees before TDC). However, earlier SOIs result in combustion instability, due to overleaning of HRF. It is more evident for a case with a high percentage energy substitution (PES) of LRF, due to the limited injected quantity of HRF. Research has shown that combustion instabilities can be improved by split injection (more than one injection), especially when they are close-coupled. In this study, the typical diesel PM-NOx tradeoff was nullified with an oxygenated, high cetane fuel, polyoxymethylene dimethyl ether (POMDME) as HRF. POMDME-natural gas DFC produced zero measurable soot emissions at all investigated conditions. However, since the lower heating value of POMDME is nearly half that of diesel, it needs longer injection durations (greater mass injected) for the same energy input. Therefore, it is important to understand the effect of end of injection (EOI) of POMDME compared to diesel for the same SOI on performance and emissions In addition, the impact of split injection strategies on performance and emissions are explored, especially at the heat release rate shape transformation region (i.e.) between SOI 320 and 330 CAD.
Phenomenological Model Development of Flash Boiling Spray for Multi-Hole Gasoline Direct Injection (GDI) Systems
Authors: Ailaboina Akhil , Saha Kaushik 
Published: November 2022

Abstract
Flash boiling occurs when a superheated liquid fuel is injected into a sub-atmospheric pressure environment. This phenomenon is often seen in a gasoline direct injection (GDI) engine under part-load conditions. The injector tip is exposed to the combustion environment, increasing the fuel temperature inside the injector up to 80–90° C. Under these flash boiling conditions, the injected liquid fuel will undergo rapid vaporization, affecting the spray structure. The flash boiling spray helps achieve better atomization of the fuel spray. However, in some conditions, due to flashing, a dense vapor cloud will form in the in-cylinder and disturb the air-fuel mixture, and lead to unwanted pollutants. Several numerical models have been developed for the flash boiling sprays. However, most of these models are hard to implement in a multi-cycle GDI engine combustion simulation. The existing flashing-based evaporation models in the CONVERGE code are not dimensionally consistent. In that regard, a phenomenological model of flash boiling spray is developed using the relevant non-dimensional numbers to help GDI engine combustion modeling under such conditions and address the issue of dimensional inconsistency in the source term formulations.
A multi-hole GDI injector from the engine combustion network (ECN) called Spray G is considered for this work. The model is developed using the CONVERGE v2.4 user-defined functions (UDFs). The blob injection method is considered for this work, and the simulations are carried out using the Eulerian-Lagrangian framework. An Unsteady Reynolds Averaged Navier-Stokes (URANS) RNG k-ε turbulence model is considered in this study. The KH-RT breakup length model is adopted for modeling spray breakup. The developed model has achieved a reasonable agreement with the experimental spray images. Comparisons of the predictions are made with the data available through ECN, such as spray penetrations and spray patternations.
Reinforcement Learning Based Control of an Organic Rankine Cycle Waste Heat Recovery System Over a Drive Cycle for Heavy-Duty Diesel Engines
Authors: Egan Daniel , Xu Bin , Zhu Qilun , Prucka Robert 
Published: November 2022

Abstract
Organic Rankine cycle (ORC) waste heat recovery (WHR) systems are of interest in the automotive sector because of their ability to convert exhaust heat into usable energy, increasing system-level brake thermal efficiency. Interest is particularly strong in the heavy-duty market as these vehicles have large footprints and heat outputs that can accommodate ORC-WHR systems. ORC-WHR systems are in the early stages of development and as a result the effectiveness of ORC-based systems throughout transient drive cycles can be difficult to quantify. One of the primary barriers preventing insight into transient performance is the lack of control maturity that exists prior to hardware implementation. Early development of control strategies allows for insights to be integrated into design earlier in the process, potentially streamlining the development cycle. ORC control development is hindered by the physical complexity of the boiler and the modeling of associated dynamics. Creating a model that captures the warm-up, power-generation, and cool-down operating regimes requires the use of a finite volume-based model (FVM) which is computationally infeasible to use with optimal control techniques such as model predictive control or dynamic programming. If the model is switched to a control oriented moving boundary model (MBM) the ability to govern the warmup and cool-down operating regimes is eliminated. This research proposes the use of a model-free reinforcement learning (RL) algorithm to create a control strategy using a FVM system model. The model-free nature of RL allows it to be trained/calibrated on models of unlimited complexity with the resulting controller capable of real-time operation. This eliminates the need for model reduction during control strategy generation and allows for the controller to handle all operating regimes the system will encounter. This study utilizes a deep deterministic policy gradient (DDPG) RL agent trained on a FVM of an ORC-WHR system. The RL agent is trained over a heavy-duty drive cycle and is capable of extracting net positive work over a transient drive cycle.
Effect of the Virtual Mass Force Term on the Critical Flow
Authors: Xu Hong , Chen Jiayue , Ming Pingjian , Cheng Xu 
Published: November 2022

Abstract
Critical (choked) flow is a highly concerning phenomenon in safety analysis for nuclear energy. During an accident, the radioactive aerosol in nuclear power plant (NPP), which is hazardous for the environment, may be released accompanying the fluid discharge. Consequently, the discharge mass flow rate prediction is crucial for engineering design and emergency response in case of nuclear accidents. Unfortunately, the critical flow is difficult to predict especially when two-phase flow exists. Developing a more accurate model for critical flow is an essential requirement to the system thermal-hydraulic (STH) codes (e.g., RELAP5, TRACE, and ATHLET, etc.) for nuclear safety analysis. The accuracy is based on a deeper understanding of the complex phenomenon of critical flow. One of the difficulties concerned with the mathematical modeling of the two-phase critical flow is the complexity of the transfer phenomena at the interface. Normally, an interfacial drag law and a virtual mass force were used to quantify the momentum transfer between the phases in the STH codes. The present study is concerned with the effect of virtual mass force on phase separation during the acceleration of a two-phase mixture. Virtual mass represents real physical effects and it can be regarded as induced inertia on the dispersed phase which is accelerating relative to the continuous phase. It has been verified that the virtual mass acceleration is objective, and the consideration of it in the two-phase flow simulation can improve the numerical stability and efficiency. Therefore, a variety of objective forms of virtual mass acceleration were derived in the last fifty years. But the influence of virtual mass force on the two-phase critical flow was seldom concentrated on owing to the lack of suitable critical flow models for studies in detail. This study is based on a developed two-phase critical flow model based on the separate conservation equations of mass, momentum, and energy for each phase. Several typical models of virtual mass force are selected and their influences on the accuracy of critical flow predictions will be studied in some detail. Furthermore, the critical flow that happened in the NPP accident scenarios may go through several flow regimes such as subcooled flow, bubbly flow, slug flow, and annular flow, etc. The impact of virtual mass force on these different stages of critical flow is another topic of this study. The results of this study can benefit a further understanding of virtual mass force, especially its influence on critical flow, and will contribute to the development of a more accurate two-phase critical flow model.
Improvement of Large Container Inspection System in Photon- Counting Mode Proved With Steel Penetration Ability
Authors: Zhang Huaxia , Wu Zhifang , Dong Tao , Jiang Shibo 
Published: November 2022

Abstract
We present the structure and characteristics of a photon-counting system for increased Steel Penetration (SP) ability in large container inspection area. Ideally, radiation images should count only unreacted photons. Conventional detectors utilize analog current integration and thus suffer from scattered signals and electronic noise which can deteriorate image quality. However, with the increasing demand for container inspection, higher requirements have been placed on image quality, scan speed as well as radiation dose. Therefore, we propose a new photon-counting mode large container inspection system that counts individual signals, in which scattered signals and electronic noise can be eliminated by setting an energy threshold.
In this paper, we give a system overview and describe the key technologies in system design. Then the improvement of the presented system is analyzed theoretically from the aspect of physical interactions that take place in the system. Simulation of the Steel Penetration model is conducted in Geant4 software. Results show that the improvement of SP ability compared with the conventional current-integration system is about 3 to 4cm Fe even if we increase the scan speed or reduce the radiation intensity, and can be 1 to 2cm more by setting an appropriate energy threshold. Along with this property, the possibility of reducing radiation dose and increasing scan speed makes this system unique for future growth of container inspection missions.
Local Damage to Reinforced Concrete Panels Subjected to Oblique Impact by Projectiles: Numerical Analysis on Test Results
Authors: Kang Zuoyi , Okuda Yukihiko , Nishida Akemi , Tsubota Haruji , Li Yinsheng 
Published: November 2022

Abstract
This study aims at proposing a numerical analysis method to evaluate local damage to reinforced concrete (RC) panel caused by projectile impact. To validate the proposed numerical analysis method, we recently conducted a series of impact tests with normal and oblique impacts due to rigid and soft projectiles. We intend to compare the numerical results with experimental results including reaction forces, damage modes of RC panel and soft projectile in oblique impact. In the numerical analysis for evaluation of local damage to RC panel, there are several key parameters, such as material properties, contact conditions between concrete and projectile. In addition to these parameters, we also focused on the reaction forces of RC panel, which is important when investigating the impact effects on structure under projectile impact. Since the stiffness of support structure is represented as a spring element in finite element (FE) model, we examined the relationship between the spring stiffness and numerically computed reaction forces in oblique impact. The numerical analysis method for oblique impact is validated, and the local damage in the RC panel is evaluated, by comparing experimental and numerical results.
Investigation of Transport Models of Radionuclides in Various Water Environments
Authors: Qu Zhengzhe , Xie Feng , Nie Baojie , Wang Liang 
Published: November 2022

Abstract
Concerning the Fukushima nuclear accident, many radionuclides were released into the marine environment, which caused contamination of many parts of the world through ocean circulation. Regarding inland nuclear power plants, freshwater habitats such as reservoirs and rivers could also be polluted by the radioactive effluents. Several models were developed to track radionuclide transport in the water environment. However, the applicability and characteristics of these models were not fully identified and compared, particularly for the different water environments. In this study, the research progress and application examples of radionuclide transport models in rivers and oceans in recent years are systematically summarized, and the methods for simulating radionuclide transport behavior in various water environments are compared. An adequate model is expected to be instrumental in assessing radioactive pollution in various water environments.
Dynamic Modeling of Nuclear Hydrogen Generation Plant Based on Multi-Modular High-Temperature Gas-Cooled Reactor
Authors: Li Junyi , Dong Zhe , Li Bowen , Huang Xiaojin 
Published: November 2022

Abstract
There has been growing interest in nuclear hydrogen cogeneration recently since hydrogen has been considered one of the prospective substitutes to fossil fuels in the future, and nuclear energy can supply the energy required for hydrogen production efficiently and cleanly. The multi-modular high-temperature gas-cooled reactor (MHTGR) is a small modular reactor with the advantage of inherent safety, and its nuclear steam supply system (NSSS) can provide steam at around 570°C. Methane Steam Reforming (MSR) is currently the most widely used hydrogen production method, and if it is combined with a carbon capture and storage system, the greenhouse gas emissions can be minimized. This paper presents the design for a nuclear hydrogen cogeneration plant that has six-module MHTGRs coupled with MSR.
Feasibility Verification of One Operator Monitoring Two NSSS Modules in Power Plant With Six High Temperature Gas Cooled Reactors Under Accident Conditions
Authors: Miao Runfa , Jia Qianqian , Li Duo 
Published: November 2022

Abstract
The multi-module high temperature gas cooled reactor (MMHTGR) adopts the design of multiple reactor modules coupled to one steam turbine. The number of modules can be as much as six. According to staffing model of the preliminary stage, each reactor operator needs to monitor and control two modules, and each NSSS (nuclear steam supply system) module has the similar displays and operating procedures. The operation concept of the multi-module plant is different from single-module HTGR. Therefore, the human performance of operators in the multi-module HTGR need to be studied.
In order to verify the feasibility of one operator monitoring and controlling two NSSS modules under accident conditions, experiments are designed. During the experiment, a variety of accident scenarios are selected, including accidents in two or more modules. During the experiment, the operator will record the completion of the operator’s tasks. At the end of each experimental scenario, each operator is invited to fill in SART scale and NASA-TLX scale for measuring situation awareness and workload. The experimental results show that because the inherent safety of the HTGRs and a high degree of automation is conducive to the operation of the reactor, it is feasible for one operator to control and monitor the two modules under the accident condition. The correlation analysis shows that there is a strong negative correlation between the operator’s situation awareness and Demand use the SART scale. The workload of operators has a strong positive correlation between Mental and Temporal in the NASA-TLX scale. By improving the components of Demand, Temporal and Mental, operators’ workload can be reduced and situation awareness can be improved.
Study on Radionuclide Migration Under Accident Conditions of Mobile Heat Pipe Small Module Reactor
Authors: Tang Jianyu , Zhou Tao , Xu Peng , Lu Huaichang , Gao Tianyu 
Published: November 2022

Abstract
Mobile heat pipe reactor has a wide application prospect in many fields. In the event of a nuclear leak, the reactor will have adverse effects on the environment. So, mastering the circumstances of nuclide migration has great value to enhance the capacity and efficiency of nuclear accident emergency response. This research uses a programming method to describe the diffusion and deposition of nuclides in the atmosphere after a leakage accident. Subsequently, further study the deposition of nuclide diffusion in the unsaturated zone. Through these studies, we can make predictions and evaluate the consequences of accidents. The result shows that there is a certain relationship between the concentration of nuclide diffusion in the atmosphere and the distance downwind direction and there is a maximum value. The maximum diffusion distance of a nuclide is positively correlated with the amount of leakage nuclide when it diffuses over a short distance and near the ground. The deposition conditions of nuclides are different under different conditions. Dry deposition flux can be neglected in short-term calculations. Wet deposition flux is the main source of the diffusion of nuclides into the unsaturated zone. Soil has a good retention effect on radionuclide diffusion and the unsaturated zone can slow the migration velocity. However, rainfall will accelerate the migration of nuclides.
Evaluation of the Parameter Importance Changes Over Time for Nuclear Reactor Transients
Authors: Xiong Qingwen , Song Gongle , Du Peng , Huang Tao , Deng Jian 
Published: November 2022

Abstract
The uncertainty analysis and sensitivity analysis are two important parts in the safety analysis of nuclear reactor accidents, and the main purpose of the sensitivity analysis is to quantify the importance of the input on the target output. In typical sensitivity analysis for the nuclear reactor transients, specific techniques such as the regression analysis or correlation coefficient analysis are utilized to calculate the sensitivity measures of the inputs on the target output at scalar points, for instance the peak cladding temperature (PCT). However, the phenomena and parameters vary significantly over time during the transients, thus the influence of each input also changes. In order to evaluate the importance changes of the inputs on the target output over time, a time-dependent global sensitivity analysis technique was developed base on the B-spline function system of the functional data analysis, the landmark registration strategy, and an efficient moment-independent sensitivity analysis method. The developed technique was adopted in the sensitivity analysis of a large break loss of coolant accident (LBLOCA) of the nuclear reactor, and the time-dependent sensitivity measures of the inputs on the maximum cladding temperature were acquired and analyzed. Results showed that the proposed technique is capable of evaluating the importance changes of the key parameters in nuclear reactor accident transients.