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Automotive engine assembly and disassembly are common and crucial programs in the automotive industry. Traditional education trains students to learn automotive engine assembly and disassembly in lecture courses and then to operate with physical engines, which are generally low effectiveness and high cost. In this article, we developed a multilayer structured virtual reality (VR) system to provide students with training in automotive engine (Buick Verano) assembly and disassembly. The VR training system is designed to have several major features, including replaceable engine parts and reusable tools, friendly user interfaces and guidance, and bottom-up designed multilayer architecture, which can be extended to various engine models. The VR system is evaluated with controlled experiments of two groups of students. The results demonstrate that our VR training system provides remarkable usability in terms of effectiveness and efficiency. Currently, our VR system has been demonstrated and employed in the courses of Chinese colleges to train students in automotive engine assembly and disassembly. A free-to-use executable file (Microsoft Windows) and open-source code are availablefor facilitating the development of VR systems in the automotive industry.

Real-time rendering has been embracing ever-demanding effects, such as ray tracing. However, rendering such effects in high resolution and high frame rate remains challenging. Frame extrapolation methods, which do not introduce additional latency as opposed to frame interpolation methods such as DLSS 3 and FSR 3, boost the frame rate by generating future frames based on previous frames. However, it is a more challenging task because of the lack of information in the disocclusion regions and complex future motions, and recent methods also have a high engine integration cost due to requiring G-buffers as input. We propose a G-buffer free frame extrapolation method, GFFE, with a novel heuristic framework and an efficient neural network, to plausibly generate new frames in real time without introducing additional latency. We analyze the motion of dynamic fragments and different types of disocclusions, and design the corresponding modules of the extrapolation block to handle them. After that, a light-weight shading correction network is used to correct shading and improve overall quality. GFFE achieves comparable or better results than previous interpolation and G-buffer dependent extrapolation methods, with more efficient performance and easier integration. [ABSTRACT FROM AUTHOR]

Hydrogen, as a promising renewable energy source, is considered to have significant potential for achieving the dual-carbon goal. In the present study, a 1D engine model is used to investigate the impact of hydrogen injection pressure and its changing law on the performance of hydrogen engines. The results indicate that under low load conditions, increased hydrogen injection pressure from 5 bar to 25 bar initially improved power performance and fuel economy and then declined them; an injection pressure of 10 bar got the highest power of 51.91 kW and thermal efficiency of 43.25%. Under medium load conditions and high load conditions, increased hydrogen injection pressure from 5 bar to 25 bar, power performance and fuel economy declined. The NOx emission of engine declined gradually with the increase of injection pressure from 5 bar to 25 bar. The NOx emission is reduced by approximately 2.5% as the injection pressure is raised from 5 bar to 15 bar, and then, as the injection pressure continues to increase, the reduction becomes less significant. Additionally, selecting the End Peak curve for hydrogen injection pressure change increased indicated power by 0.4 kW, thermal efficiency by 0.2%, and reduces NOx emission by around 8% than other curves. The study also found that near-zero emissions can be achieved when λ value exceeds 2.5. • Different hydrogen injection pressure and its variation law are investigated. • The effects of different hydrogen injection pressures on engine performance are investigated. • The influences of various hydrogen injection pressure variation law on engine performance are investigated. • The near zero emission conditions of the engine are investigated. [ABSTRACT FROM AUTHOR]

Today, a promising direction in the development of the field of application of linear motors is their use in the construction of well pumps. This makes it possible to significantly increase the stroke of the working body and improve the efficiency of oil production compared to the traditionally used rod-well analog. When solving such a problem, a difficult issue is forecasting and ensuring the traction force during the working trajectory of the movement, which is what the research conducted in the work is aimed at. As the main result, the application of the grapho-analytical method in the calculations and modeling of the characteristics of linear motors with complex trajectories of motion is substantiated. In the course of calculations with its use, the possibility of a four-fold increase in the traction force with a general improvement in the static characteristics of the engine in a given range of movement at the permissible speed of the working body was proven. References 5, figures 6. [ABSTRACT FROM AUTHOR]

The organic Rankine cycle (ORC) is an effective way for engine waste heat recover (WHR). The selection of the working fluid is crucial. In recent years, low GWP and ODP working fluid have been invented. For R123, which is commonly used in engine ORC-WHR system, the alternative working fluid is R1233zd(E). In order to explore the performance of R123 and R1233zd(E) when applied to ORC-WHR system, this study conducted experimental studies of R123 and R1233zd(E) under a wide range of engine working conditions. The experiments were carried out under seven sets of engine working conditions with gradually increasing loads. Variable operating parameter experiments were carried out for R123 and R1233zd(E) at each engine load. The selected operating parameters include expander speed and superheat degree. The experimental results show that R123 has higher output power and thermal efficiency compared to R1233zd(E) at all engine conditions.The maximum output power and thermal efficiency of R123 are 1.55 kw and 5.81% respectively.The maximum output power and thermal efficiency of R1233zd(E) are 1.43 kw and 5.29% respectively. Taking the net output power as the evaluation index, the optimal expander speed of R123 is higher than that of R1233zd(E) under the same engine working condition, and the superheat degree has little effect on the net output power. [ABSTRACT FROM AUTHOR]

AbstractCollaborative Augmented Reality (CAR) involves multiple users working together in an augmented reality setting to accomplish tasks. In CAR, transparent techniques enable users to see occluded objects in complex environments, yet they often struggle to discern which part of a complex object they have selected. Workspace awareness refers to understanding how others interact within a shared workspace and influence the choice of visualization techniques. This study investigated workspace awareness regarding different object selection visual feedback in co-located CAR. It explored four technique variations: Hi (highlight), Hi-Ray (ray emitting), Hi-View (view switching), and Hi-RV (ray emitting and view switching). Thirty-two participants were divided into 16 pairs, with an instructor demonstrating how to assemble an engine component and a student replicating the process using the four visualization techniques. Results showed the visualization techniques did not affect task completion time significantly. The Hi and Hi-Ray technique had the highest error rate, while the Hi-RV technique had the lowest. However, users preferred the Hi-View technique, which scored highest in interaction, collaboration quality, workspace awareness, and required less workload. To enhance awareness, participants pointed out the weakness in the combination of visual feedback, particularly with the ray emitting technique, which causes confusion when multiple objects are selected due to visual clutter. They suggested that integrating audio feedback could help alert users to their choices, and using color-based indicators could distinguish different actions, such as indicating correct or incorrect placement of virtual objects. [ABSTRACT FROM AUTHOR]

This article explores the potential of the Unreal Engine as a tool for creating realistic 3D visualizations of large-scale areas (1000 km2 and more) using GIS datasets. Unlike small-scale visualizations, large-scale visualizations are rare and often not public, which presents significant problems since they present different challenges and require different approaches. This article presents several relevant scientific studies and projects that have successfully used game engines for similar purposes. This case study focuses on the computational techniques used in Unreal Engine for the 3D visualization of GIS data and the potential application of Unreal Engine in large-scale geo-visualizations. It explores the potential for using GIS data within a game engine, including plug-ins that provide additional functionality for working with GIS data, such as the Vitruvio plug-in to implement procedural modeling of buildings. The case study is applied to GIS datasets of the historical Vltava Valley covering an area of 1670 km2 to demonstrate the unique challenges of using Unreal Engine to create realistic visualizations of large-scale historical landscapes. The resulting visualizations are presented. The practical application of this research provides insights into the potential of the Unreal Engine as a tool for creating realistic 3D visualizations of large-scale historical areas. [ABSTRACT FROM AUTHOR]

Turbofan engines exhibit pronounced nonlinearity due to component characteristics and thermal processes, necessitating linearization to connect engine control with linear control theory. Off-equilibrium linearization offers excellent transient tracking and controller performance, making it ideal for military turbofan engines with rapid acceleration and deceleration. Hardware-in-Loop (HIL) experiments are crucial for verifying controller performance, but time delays in the HIL platform can cause oscillations in state variables when using this linearization method. To address this issue, this paper introduces an off-equilibrium linearization-based control strategy. This strategy employs an off-equilibrium linearized model to approximate the nonlinear time-delay system, followed by designing an H8 controller for the linear time-delay system. The effectiveness of this approach applied to turbofan engines, including its antidelay and robust tracking capabilities, is validated through simulations, HIL experiments, and semiphysical experiments. [ABSTRACT FROM AUTHOR]

Aiming at the problem of torque fluctuations and intake pressure fluctuations caused by cycle cylinder deactivation, we introduced a refined control strategy encompassing fixed cycle frequency with fixed deactivation frequency, variable cycle frequency with fixed deactivation frequency, and variable cycle frequency with variable deactivation frequency. The cycle cylinder deactivation rate is determined by controlling the cycle frequency and the cylinder deactivation frequency, which provides a new method for exploring the torque fluctuation of the cycle cylinder deactivation. Furthermore, we introduced an intake compensation method based on the cylinder deactivation compensation coordinate system is proposed. The non-uniformity of the intake air volume of each cylinder of the cycle cylinder deactivation is improved by changing the valve lift. After compensation, the non-uniformity of the intake air volume and the mean indicated pressure of each cylinder are within 2%, and the maximum torque fluctuation is reduced by 52%. It provides a useful reference for enhancing the dynamic smoothness of cylinder deactivation in engines. [ABSTRACT FROM AUTHOR]

Nowadays, engine experimental research represents a very expensive field within the automotive industry, but it remains fundamental for engine and vehicle development. The present work aims to investigate a novel approach for engine control system calibration, by adopting machine learning techniques to model physical parameters of the engine starting from experimental data measured at the test bench. The main goal is to create a methodology which accelerates the calibration process without losing accuracy. A model that estimates air mass flow is created by adopting either a tree ensemble model or an artificial neural network trained on a small dataset, which was previously acquired at the test bench using a random calibration of the volumetric efficiency map. The model's performance is first validated on a larger, random dataset. Then, the volumetric efficiency calculated from the air mass flow model estimation is used to calibrate the transfer function of the Engine Control Unit. Finally, the sensitivity of the model error correlated with the number of data points acquired is used in order to determine the best practice for a Design Of Experiment, which minimizes data acquisition. The methodology proposed can lead to reduced time and costs of the whole calibration process of the engine, without losing accuracy. The analysis was conducted on the entire vehicle, which is crucial for drivability, especially in motorcycles since they are highly sensitive to air-to-fuel ratio adjustments. This work demonstrates that machine learning models can be adopted for the fine-tuning of the calibration process, which is normally performed manually. [ABSTRACT FROM AUTHOR]

As the flight envelopes of turbine-based combined cycle (TBCC) engines expand, ensuring reliable ignition and flame stability under varying conditions becomes increasingly critical. Previous work has shown a significantly changed ignition performance and flow pattern in cavity-based combustors when strut structure parameters were altered, indicating a strong correlation between the ignition process, flame structure, and the strut configuration. This suggests that further investigation is required to determine the optimal strut design. Therefore, this study examines the impact of various strut configurations through numerical simulations, validated by high-speed imaging. Findings show that the tail-groove strut designs improve the flame propagation performance compared to the normal struts, with a critical depth beyond which further increases do not enhance performance. Changes in strut length have a lesser impact than depth. Flow analysis indicates that tail-groove struts create additional recirculation zones that enhance fuel atomization and flame stability. These results suggest that optimizing strut configurations is vital for achieving reliable ignition and flame stability, advancing the development of efficient engines across a wide range of operational conditions. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the performance enhancement of a novel X-type rotary engine through hydrogen doping and proposes an optimal control strategy under part-load conditions. For this reason, an integrated model combining a dual zone model with recurrent neural network model for a hydrogen-doping X-type rotary engine is developed. Then, the effects of operating parameters on the comprehensive performance of engine are analyzed. Finally, an optimal multi-variable control strategy (OMCS) is introduced to achieve optimal performance under part-load conditions. The results show that the optimization of hydrogen is more pronounced at high rotational speeds, small ignition angles, or lean combustion conditions. Compared with single-variable control strategies, OMCS offers a broader regulation range and can maintain thermal efficiency above 0.27. At high loads, OMCS achieves high thermal efficiency by adjusting the equivalence ratio and ignition timing, albeit with a slight compromise on NO emission performance. • A novel hydrogen-doping X-type rotary engine with special structure is proposed. • A novel integrated model combining dual zone model and RNN is established. • Effects of multi-parameters on power, thermal efficiency and emission are analyzed. • The engine optimal control strategy under part-load conditions is investigated. [ABSTRACT FROM AUTHOR]

The InfiniBand (IB) interconnection technology is widely used in the networks of modern supercomputers and data centers. Among other advantages, the IB-based network devices allow for building multiple network topologies, and the IB control software (subnet manager) supports several routing engines suitable for the most common topologies. However, the implementation of some novel topologies in IB-based networks may be difficult if suitable routing algorithms are not supported, or if the IB switch or NIC architectures are not directly applicable for that topology. This work describes the implementation of the network topology known as KNS in a real HPC cluster using an IB network. As far as we know, this is the first implementation of this topology in an IB-based system. In more detail, we have implemented the KNS routing algorithm in the OpenSM software distribution of the subnet manager, and we have adapted the available IB-based switches to the particular structure of this topology. We have evaluated the correctness of our implementation through experiments in the real cluster, using well-known benchmarks. The obtained results, which match the expected performance for the KNS topology, show that this topology can be implemented in IB-based clusters as an alternative to other interconnection patterns. [ABSTRACT FROM AUTHOR]

In Puerto Rico and each of the U.S. Virgin Islands, stationary steam engines survive on their original foundations and stand in testament to the long history of sugar production in the American territories of the Caribbean. In total, six beam engines, seven horizontal engines, one vertical engine, and a compound engine exist on the islands in various states of preservation, many amid the ruins of the plantations (haciendas) whose output they made possible. The whereabouts of an eighth horizontal engine recorded in 1976 remains unknown. Most were imported from Britain in the second half of the nineteenth century, but at least one is of American build. These machines not only provide unique examples of the adaption of steam technology to the needs of nineteenth-century sugar production but are also lasting symbols of an industry that once dominated the economy of these islands and remain deeply entwined in their history. [ABSTRACT FROM AUTHOR]

A micro-tiller vibrates severely during the rotary tillage process, which may cause operators to develop white finger disease. However, for most vibration models, the acting force between the soil and the rotary cutter roll was simplified to only a constant or sine curve, which may not describe the whole dynamic. Rotary tillage processes have been simulated based on the smoothed particle hydrodynamics method in this paper. The acting forces of the soil on the cutter roll have been obtained with the simulation model. Four different working conditions were simulated. The average error between the calculated forces and the simulated mean forces is 10.96%, which proves the SPH model. By introducing simulated acting forces into the vibration model, a new vibration model of the micro-tiller, which includes the soil–blade interaction, has been constructed. Time and frequency characteristics were simulated with the new vibration model. The errors between the simulated and tested RMS values are 4.28%, 5.03%, and 6.35% for the engine, cutter roll, and right handle, respectively. Two domain-dominant frequencies were found with the vibration model, namely 44.7 Hz and 257.0 Hz. It is helpful to reveal the whole dynamic map of micro-tillers. [ABSTRACT FROM AUTHOR]

Cooled spray (CS) technology passively reduces particulate matter (PM) emissions from diesel engines compared to non-CS-equipped diesel engines. CS inserts are mounted near the injector nozzle and control mixing so that the fuel and air can premix while limiting combustion near fuel-rich zones, thereby reducing the formation of particulate matter. CS components contain no moving parts and could be installed as a retrofit or built into new engines. However, CS technology is early in its development, and further investigations are needed to understand the overall performance implications and practicality of the technology. In this paper, we investigate several important aspects of CS, providing a clearer picture of some challenges and potential benefits of CS. Two alignment techniques are used to characterize measurement ease and bias, namely, an optical alignment and spray-plug impact alignment. While the optical technique facilitates alignment more easily, a bias was measured between the optical and spray-plug techniques, suggesting the optical technique may have insufficient accuracy without additional corrections. We also evaluate the engine performance of a well-aligned and poorly aligned CS insert, compared to the baseline configuration. The poorly aligned insert shows slower combustion than the baseline and mixed overall performance. However, the well-aligned insert shows faster combustion than the baseline and PM emission reduction at most operating conditions, with some conditions showing PM reduction up to 80%. The results of this paper highlight the alignment challenges of CS technology as well as the potential PM reduction benefit of the technology. [ABSTRACT FROM AUTHOR]

The composition of a pasty propellant for small-sized space engines has been proposed. For this propellant, a research of the burning process was carried out. This research included the determination of the burning rate law, the characteristics of the agglomeration process, and the properties of the surface layer. The presence of an intermediate structure, a skeleton layer, during the burning of such propellants, and the nature of the influence of pressure, additives, and the size of oxidizer particles on this structure, have been established. The determining influence of this structure on the burning process is shown. Composition solutions that provide control over the burning rate law of such propellants are determined. These solutions make it possible to change the absolute value of the burning rate, as well as its dependence on pressure. Regularities of the agglomeration process have been established. These regularities are associated with the features of the formation of the skeleton layer, which depend on the structure of the propellant, pressure, and the presence of additives. [ABSTRACT FROM AUTHOR]

The relationship between the power consumed in the engine and the power take-off (P.T.O.) shaft of a maize silage harvester is critical to understanding the efficiency and performance of the harvester. The power consumed in the engine directly affects the power available for use on the P.T.O. shaft, which is the power source for the suspended silage harvesters. The research aimed to predict the power consumption of the P.T.O. shaft based on the power consumption of the tractor engine at different operating parameters, which are two applications of the P.T.O. shaft (540 and 540E rpm) and two forward speeds (1.8 and 2.5 km/h) using machine learning algorithms. The best results in terms of engine power consumption were achieved in the 540E P.T.O. application, and the forward speed was 1.8 km/h. The results also gave a correlation between the power consumed by the engine and the P.T.O shaft of 87%. Regarding prediction algorithms, the Tree algorithm gave the highest prediction accuracy of 98.8%, while the KNN, SVM, and ANN algorithms gave an accuracy of 98.1, 60, and 60%, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Automotive Engineer (1674-6546) is the property of Auto Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During the process of moving, the power splitting hybrid vehicle is required to start the engine to transfer from pure electric mode to hybrid drive mode. According to the structural characteristics of the system, the engine starting process was divided into four stages, the engine starting process was established, and a multi-stage engine starting coordination control strategy was designed. In the engine reverse-drag process, the coordination control strategy was transformed into the optimal rotation rate tracker problem. In order to solve the load torque required in the tracking problem, a reduced-order observer was designed. Finally, the validity of the coordination control strategy was verified on the simulation platform of the electro-mechanical composite transmission system. The feasibility of the coordination control strategy was verified by hardware-in-the-loop simulation. The results show that the engine start coordination control strategy could achieve steady and fast engine start control. The maximal impact of the whole vehicle is reduced from 30 to 2.5 m/s3. [ABSTRACT FROM AUTHOR]

Streaming Linked Data represents a domain within the Semantic Web dedicated to incorporating Stream Reasoning capabilities into the Semantic Web stack to address dynamic data challenges. Such applied endeavours typically necessitate a robust data modelling process. To this end, RDF Stream Processing (RSP) engines frequently utilize OWL 2 ontologies to facilitate this requirement. Despite the rich body of research on Knowledge Representation (KR), even concerning time-sensitive data, a notable gap exists in the literature regarding a comprehensive survey on KR techniques tailored for Streaming Linked Data. This paper critically overviews the key ontologies employed in RSP applications, evaluating their data modelling and KR abilities specifically for Streaming Linked Data contexts. We analyze these ontologies through three distinct KR perspectives: the conceptualization of streams as Web resources, the structural organization of data streams, and the event modelling within the streams. An analytical framework is introduced for each perspective to ensure a thorough and equitable comparison and deepen the understanding of the surveyed ontologies. [ABSTRACT FROM AUTHOR]

Transfer learning is an effective approach to address the decline in generalizability of intelligent fault diagnosis methods. However, there has been a persistent lack of comprehensive and effective metrics for assessing the transferability of cross-domain data, making it challenging to answer the fundamental question in transfer learning: "When to transfer". This study proposes a novel hybrid transferability metric (HTM) based on weighted correlation-diversity shift. The metric introduces a correlation shift measurement based on sparse principal component analysis, effectively quantifying distribution differences in domain-invariant features based on the sparse representation theory. It also designs a diversity shift measurement based on label space differences, addressing the previously overlooked impact of label variation on transferability. The proposed transferability metric is validated on four types of cross-domain diagnosis tasks involving piston aero engines. The results show that in diagnostic scenarios involving both supervised transfer learning and extreme class imbalance problems, HTM accurately predicted the transferability of the target tasks, which aligned with the actual diagnostic accuracy trends. It provides a feasible method for predicting and evaluating the applicability of transfer learning methods in real-world scenarios. [ABSTRACT FROM AUTHOR]

Model-based control shows promising potential for engine performance improvement and future aero-propulsion requirements. In this paper, an auto-updating thrust variation mitigation (AuTVM) control approach using on-board model strategies is proposed for gas turbine aero-engines under in-service degradation effects, which aims at active thrust regulation and acceleration protection in a simultaneous way. The AuTVM control is integrated with an on-line block, based on a reliable on-board engine model, and an off-line part for the periodical update of control parameters via post-flight engine monitoring data. The core feature of the AuTVM control is a set of auto-updating loops within the on-line part, including thrust regulation loop, surge margin loop, turbine entry temperature loop, and the steady loop, whose control parameters are periodically adjusted with increasing flight cycles. Meanwhile, an industrial sensor-based baseline controller and two tailored model-based controllers, i.e., a thrust variation mitigation (TVM) controller with fixed gains and a self-enhancing active transient protection (SeATP) controller with pro-active transient protection and passive thrust control, are also developed as comparison bases. Numerical simulations for idle to full-power acceleration tests are carried on a validated aero-thermal turbofan engine model using publicly available degradation data. Simulation results demonstrate that both new engines and severely degraded engines regulated by the AuTVM controller show significant thrust response enhancement, compared to the baseline controller. Moreover, thrust variation at the maximum steady state of degraded engines, which exists within the SeATP controller and the baseline controller, is suppressed by the proposed AuTVM controller. Robustness analysis against degradation uncertainties and sensor accuracy confirms that the AuTVM controller owns a closer maximum steady-state thrust distribution to the desired value than those of the SeATP and the baseline controller while utilizing transient margins of controlled engines more effectively. Hence, the control performance of the AuTVM controller for in-service engines is guaranteed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Low-temperature gasoline combustion (LTGC) with additive-mixing fuel injection (AMFI) is a new combustion strategy that has been demonstrated to deliver 9%–25% better brake thermal efficiency than similar-sized market-leading diesel engines over the operating map. Moreover, the LTGC-AMFI engine shows near-zero smoke, and NOx emissions are 4–100 times lower than those of a diesel, sufficiently low that no aftertreatment, or only passive NOx aftertreatment, would be sufficient (diesel exhaust fluid is not required). LTGC-AMFI combustion is based on kinetically controlled compression ignition of a dilute charge with a variable amount of low-to-moderate fuel stratification. Fast combustion control is provided by adding minute amounts of an ignition-enhancing additive into the fuel each engine cycle to control its reactivity. This strategy was used to operate a medium-duty (MD) LTGC-AMFI engine at loads from idle to 16.3 bar BMEP and speeds from 600 to 2400 rpm with regular E10 gasoline, which covers nearly the entire operating map of a typical MD engine. Turbine-out temperatures were sufficient for an oxidation catalyst to control hydrocarbon and CO emissions. Autonomie simulations over the GEM ARB Transient and the GEM 55 mph Cruise driving cycles for class-6 trucks using this technology showed fuel economies of 8.1 and 11.4 mpg-gasoline-equivalent, respectively, corresponding to 18.6% and 13.4% improvements over a similar-size diesel engine. Engine-out NOx emissions were 0.024 and 0.01 g/bhp-h, respectively, well below current U.S. emission standards. These results show that switching from diesel to LTGC-AMFI engines would greatly reduce greenhouse gas (GHG) emissions for off-road, MD and HD applications, which will continue to rely on combustion engines because electrification is not practical in the foreseeable future. With their reduced fuel consumption, the lower cost of gasoline compared to diesel fuel, and much lower aftertreatment costs, LTGC-AMFI engines also offer a significantly lower total cost of ownership. [ABSTRACT FROM AUTHOR]

Ammonia-hydrogen engines are promising for heavy-duty, long-distance transportation, while the lower hydrogen energy share (X H2) in ammonia-hydrogen fuels facilitates hydrogen storage and use. In this study, a numerical investigation of engine performance based on an engine with ammonia port injection and different hydrogen jet ignition strategies at a fixed X H2 of 3% was conducted. The results show that too-early hydrogen injection results in lower hydrogen concentration and weak ignition in the pre-chamber, while too-late injection results in less hydrogen entering the main chamber, making more ammonia not mix well with the hydrogen, both of which increase the combustion duration. Hydrogen injection at the bottom dead center before the compression stroke mixes the hydrogen with the ammonia preliminary and leads to the formation of a high-temperature, slightly lean-burn region during the combustion, which worsens NO emission but reduces N 2 O emission. Compared with hydrogen single injection, splitting the same mass into two equal-mass injections favors higher peak pressures, shorter combustion durations, and higher indicated thermal efficiency (ITE). Injections at 360 and 90 °CA before the top dead center, respectively, achieve at least 1% relatively higher ITE with similar NO, NH 3 , and N 2 O emission performance compared with the single injection. • Study of a large bore H 2 active jet ignition NH 3 –H 2 engine at 3% H 2 energy share. • Multiple injection favors shorter combustion durations and higher engine efficiency. • Injection at the bottom dead center likely to lead to high NO and low N 2 O emissions. • Injecting hydrogen too early or too late both prolongs the combustion duration. [ABSTRACT FROM AUTHOR]

Density is an important indicator for evaluating diesel fuel quality that directly affects the injection timing and injection rule of the engine, and also has a significant impact on the spray broken particle size, the spray penetration distance, the spray cone angle, and so forth, which in turn affects the combustion process and pollutant emission of the compression-ignition engine. Therefore, it is important to accurately predict the diesel fuel mixture density in industrial and compression-ignition engines. However, the mathematical models for predicting the density of diesel fuel mixture with changed temperature are relatively lacking and less accurate, especially for ternary diesel fuel mixtures with different physicochemical properties. This paper proposes a mathematical model including binary and ternary diesel mixtures under changed fuel volume fraction and temperature, and published data were used for verification. The data verification results show that: for the density prediction of binary diesel fuel mixtures at constant temperature, the average relative deviation (ARD) is 0.0245%, the RMS error (RMSE) is 0.000344, and the correlation coefficient (R) is 0.9993. For the density prediction of binary diesel fuel mixtures at changed temperature, the ARD is 0.0609%, the RMSE is 0.000695, and R is 0.9980. For the density prediction of ternary diesel fuel mixtures at constant temperature, the ARD is lower than 0.0571%, the RMSE is lower than 0.000610, and R is higher than 0.9861. For the density prediction of ternary diesel fuel mixtures at changed temperature, the ARD is 0.0484%, the RMSE is 0.000513, and R is 0.9996. The diesel mixed fuel density prediction model proposed in this paper has good accuracy and calculation convenience, and provides important reference value for measuring or designing the density of diesel mixed fuel in the field of compression-ignition engines. [ABSTRACT FROM AUTHOR]

In an internal combustion engine, interactions of fuel droplets and heated walls can significantly affect the combustion process and engine performance. The formation and characteristics of secondary droplets from drop-wall interactions are functions of various factors such as fuel properties, impact velocity, ambient conditions, and wall temperature. Understanding the impact behavior is important to optimize the distribution of the fuel-air mixture for efficient and clean combustion and to develop a comprehensive spray-wall interaction model. In this study, three-dimensional smoothed particle hydrodynamics (SPH) simulations are performed to investigate the interactions of fuel droplets with a heated wall at atmospheric and elevated pressures over a range of Weber numbers (We). The SPH model is validated using available experimental data. Secondary atomization is characterized by using size distributions for different fuels. The resulting droplets vary in size, where secondary droplets are mostly below 7 µm in diameter. Following these cases, this paper qualitatively describes the impact process and proposes empirical correlation relating the mean secondary droplet size to ambient pressure in the film-boiling regime. Postimpingement vaporization characteristics are also analyzed and compared for fuels with drastically different vapor pressures. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation of the effect of wing integration on the aerodynamic behavior of a typical large civil aero-engine exhaust system at wind-milling flow conditions. The work is based on the dual stream jet propulsion (DSJP) test rig, as will be tested within the transonic wind tunnel (TWT) located at the aircraft research association (ARA) in the UK. The DSJP rig was designed to measure the impact of the installed pressure field due to the effect of the wing on the aerodynamic performance of separate-jet exhausts. The rig is equipped with the dual separate flow reference nozzle (DSFRN), installed under a swept wing. Computational fluid dynamic simulations were carried out for representative ranges of fan and core nozzle pressure ratios (CNPR) for "engine-out" wind-milling scenarios at end of runway (EOR) takeoff, diversion, and cruise conditions. Analyses were done for both isolated and installed configurations to quantify the impact of the installed pressure field on the fan and core nozzle discharge coefficients. The impact of fan and core nozzle pressure ratios, as well as freestream Mach number and high-lift surfaces on the installed suppression effect, was also evaluated. It is shown that the installed pressure field can reduce the fan nozzle discharge coefficient by up to 16%, relative to the isolated configuration for EOR wind-milling conditions. The results were used to inform the design and setup of the experimental activity which is planned for 2023. [ABSTRACT FROM AUTHOR]

The integrated design of a variable cycle engine (VCE) and an aircraft thermal management system (TMS) is investigated. The integrated system is designed using the multiple design point approach in order to achieve required performance metrics at points other than the cycle design condition. The VCE architecture is a three stream design where the third stream is split off after the fan, exhausting through a separate third-stream nozzle. The primary air stream passes through a low-pressure compressor before splitting into an inner bypass stream and a core stream. The inner streams mix aft of the low-pressure turbine and exhaust through a core nozzle. The variable cycle engine utilizes variable compressor inlet guide vanes, a variable area bypass injector at the core stream mixing plane, and variable throats in the two exhaust nozzles. The TMS architecture is an air cycle system using air bled from the high-pressure compressor. The effect of integrating the TMS into the engine design loop is investigated. A comparison is made to prior studies where the same TMS architecture was connected to a low bypass ratio turbofan engine. The comparison shows that the variable cycle engine is able to improve heat dissipation capability versus a ram air cooled system, while eliminating the airframe integration impact that comes with a separate ram-air stream. Lastly, the impact of modulating the variable geometry features on overall cooling capability is investigated. Results are presented for individual operating points as well as at the aircraft mission level. [ABSTRACT FROM AUTHOR]

Microgas turbines are an on-site power and heat generation technology with a small footprint, low gaseous (NOx) and acoustic emissions, low maintenance, and high-grade heat. They entered the market at the dawn of the twentieth century; nevertheless, they achieved minimal success and a marginal role in the microgeneration market. Reciprocating internal combustion engines (ICE) raised considerable barriers hindering their market deployment, and fuel cells are also set to compete in this segment. In this scenario, this work presents an analysis of competitiveness grounded in the theory of constraints (TOC). To this end, a specific key performance indicator (KPI) has been produced, which combines technical, economic, and operational factors according to the end-user requirement. This indicator is a function of several penalty factors representing technology and market barriers, which aims to yield a unique insight into the most competitive technology for a given application, accounting for the uncertainty deriving from technical and economic elements. This novel methodology is applied to a new potential niche market: Power-to-Hydrogen-to-Power for remote applications. The methodology is applied to an independent rural community in South Wales for which a backup power system is assessed. Four technologies are considered in the analysis: reciprocating engines, fuel cells, and two different microturbines layouts. Finally, this work provides an overview of the possible R&D&I paths necessary to increase the competitiveness of microgas turbines in certain markets. [ABSTRACT FROM AUTHOR]

To achieve a typical operating mode selection scheme, this paper conducts research on an adaptive cycle engine with fan on blade (FLADE). Based on the principles of aerodynamic thermodynamics of each component, a complete machine calculation model for this configuration with triple bypass mode is established on the MATLAB/Simulink platform. On the basis of this model, the performance of this configuration under different typical operating conditions of two working modes during the throttling process is analyzed by reducing iterative and residual variables. The simulation results show that under ground operating conditions, the triple bypass mode has higher thrust at low speed compared with the single-add-third bypass mode, while at high speed it is the opposite. The single-add-third bypass mode can be used for take off under high-power ground conditions, and for subsonic cruise conditions with low thrust requirements, the mode selection valve (MSV) can be activated to operate the engine in triple bypass mode after the aircraft climbs during the phase. [ABSTRACT FROM AUTHOR]

Water injection (WI) is a well-known technique to mitigate knocking phenomena, reducing the in-cylinder gas temperature with a high heat of vaporization and specific heat of water. In this study, the effect of WI directly into the cylinder on fuel efficiency was investigated using a 2.0 L naturally aspirated (NA), four-cylinder, port fuel injection (PFI)-spark-ignited (SI) engine. Spray visualization of water injection by a commercial gasoline direct-injection (GDI) injector was performed to elucidate the water evaporation characteristics. In engine experiments, combustion characteristics were analyzed by adjusting the WI timing and amount. Synergistic effects with other gas dilution techniques, such as EGR and Lean burn, were also investigated. The spray image of WI showed poor evaporation of water compared to gasoline, even at high fuel temperatures. The optimal timing of WI was advanced up to the early intake stroke due to the harsh conditions of NA engines for water evaporation compared to turbocharged engines. With the combination of EGR, the optimal WI timing was advanced by the compression stroke, and further fuel efficiency improvement was achieved. In lean combustion, WI can improve both combustion stability and fuel efficiency. [ABSTRACT FROM AUTHOR]

Estimates of doses inside the spacecraft were carried out for flights to the Moon using low-thrust engines. The characteristics of the trajectory, which is significantly different from the Hohmann trajectory, are taken into account. Such a trajectory causes a long stay inside the radiation belts, which can cause disruptions in the operation of onboard equipment. It turned out that, during long-term transportation of food products, they may be damaged under the influence of radiation. This is extremely important in the case of the creation of habitable stations on the Moon surface or near-Moon orbit. The presented results can be used in the preparation of future space experiments. [ABSTRACT FROM AUTHOR]

In this study, the effects of three injection parameters on the propagation and instabilities of rotating detonation waves (RDWs) in a kerosene/air rotating detonation engine (RDE) with an S-shaped isolator are experimentally evaluated. The dimensionless parameter momentum flux ratio is considered a pivotal factor, and the influence of the injection geometry factors is analyzed. An empirical formula concerning the characteristic factor of oxidizer-fuel blending is derived to facilitate the RDE injection configuration design. The research reveals a significant correlation among the injection parameters, kerosene-air momentum flux ratios, and instability of RDWs. High dimensionless injection parameters do not necessarily result in a stable RDW phenomenon. Stable RDWs and unstable detonations are discussed under various injection parameters and momentum flux ratios. Additionally, a statistical analysis of the detonation instability is conducted, revealing two distinct cyclic categories: ignition-extinguishment-ignition and attenuation-recovery-attenuation. Two pathways of RDW instability propagation are identified to summarize the evolutionary processes of these variations and elucidate their mechanisms. Changes in the injection parameters cause the RDW to develop in two unstable orientations, resulting in the extinguishing and re-generating phenomenon of the RDW. [ABSTRACT FROM AUTHOR]

The pre-swirl system is essential for delivering cooling air to turbine blades within aviation engines. To explore the impact of the inner seal on the pre-swirl system, a high pressure ratio and high rotational speed experimental platform was constructed. The impact of inner seal inflow and outflow on the pre-swirl system's performance was evaluated. In response to the adverse effects of inner seal inflow on the system, a bypass structure was proposed to divert the inner seal flow, and the optimization effects and underlying mechanisms of the bypass structure were analyzed through a combination of experimental and numerical simulation approaches. The results indicate that the impact of inner seal outflow on the system is minimal, with the maximum variation in the temperature drop efficiency remaining below 1.9% under experimental conditions. Inner seal inflow, on the other hand, can have a significant negative impact on the system's performance. At a pressure ratio of 1.6, increasing inner seal inflow ratio leads to a decline in temperature drop efficiency from 0.55 to 0.43, representing a reduction of 21.8%. The bypass structure for inner seal can effectively prevent the mixing of inner seal flow with the mainstream within the pre-swirl cavity, reducing the pressure and temperature within the pre-swirl cavity. At a pressure ratio of 1.6 and inner seal inflow ratio of 15%, the specific work done by the airflow increased from 9.23 to 12.72 kW/(kg/s), increased by 37.8%, and the system temperature drop efficiency increased from 0.426 to 0.546, representing a 28.0% increase. [ABSTRACT FROM AUTHOR]

This study presents an analysis of a two-state quantum mechanical Carnot-like engine using diatomic molecules i.e., the Morse oscillator MO, as the working substance. The engine's cycle consists of two adiabatic and two isoenergetic processes. The performance parameters such as the power output, dimensionless power (with its efficiency) and the optimal region of the engine were determined by considering the potential width L moving with finite speed. The results obtained in this work are found to be an analog of the classical Carnot heat engine. Notably, when comparing our results with those obtained using different working substances, such as the Harmonic oscillator HO within a similar engine setup, our analysis demonstrates that the MO stands out as a more potent working substance with enhanced efficiency for our engine. [ABSTRACT FROM AUTHOR]

This paper introduces a feedforward control method for physical systems that can be described with linear parameter-varying (LPV) models. The proposed feedforward controller structure is consequently derived from a generic LPV representation and is shown to be identifiable directly from noisy measurement data. The identified structure is advantageous for feedforward control, as using a simple least squares algorithm allows to parameterise basis functions representing the required input trajectory to follow a given output trajectory. Also, with the proposed regularisation, the input trajectory remains bounded even when the physical system exhibits non-minimum phase behaviour. Additionally, the proposed controller structure does not possess states but only considers the inputs and outputs signals and their derivatives, leading to a unique physical interpretation of each controller's parameter. Multiple feedforward controllers identified at various operating points can therefore be directly merged to create a parameter-varying controller. A nonlinear and locally non-minimum phase system is considered in this study, i.e. an engine air path, to evaluate the performances of the proposed feedforward strategy. The controller parameters are first identified from noisy measurement data, and then the proposed feedforward controller is implemented with a feedback controller to track the exhaust pressure and $ \mathrm {NO}_{\mathrm {x}} $ NO x concentration. Using a detailed physical simulation of the engine air path, the proposed feedforward strategy showed encouraging output tracking performances compared to state-of-the-art control methods. The presented feedforward method is shown to be straightforward to identify and calibrate while guaranteeing a contained computational complexity and being applicable to many physical systems thanks to its modularity. [ABSTRACT FROM AUTHOR]