BURA Collection:

Dynamic transient control of hydrogen direct-injection SI engines: effects of ramp duration on engine performance and abnormal combustion

Thu, 13 Aug 2026 00:00:00 GMT

Title: Dynamic transient control of hydrogen direct-injection SI engines: effects of ramp duration on engine performance and abnormal combustion Authors: Zaman, Zayne; Mohamed, Mohamed; Wang, Xinyan; Zhao, Hua; Harrington, Anthony; Hall, Jonathan Abstract: Hydrogen internal combustion engines offer a route to near-zero carbon on-road transport while preserving existing engine manufacturing and calibration know-how. Translating that potential into real-world driving, however, depends on transient control; steady-state maps alone cannot guarantee either safe operation or low NOx emissions during load steps. This paper reports a controlled transient sweep on a 0.4 L single-cylinder direct-injection spark-ignition hydrogen research engine. Five ramp durations (1.38, 1.08, 0.84, 0.48 and 0.24 s) were evaluated at a constant engine speed of 2,000 rpm with a target relative air–fuel ratio of 2.75 under closed-loop feedback control. The measurements track injection pulse width, spark timing, boost, lambda, IMEP, peak in-cylinder pressure and the maximum pressure rise rate (𝘙_max) through each transient. As ramp duration is shortened, lambda excursions and air-path overshoot grow rapidly: at 0.24 s the in-cylinder pressure overshoot approaches the mechanical safety limit, IMEP overshoots the steady-state target by about 22 %, and 𝘙_max exceeds the 600 kPa/°CA calibrated threshold. With a ramp of 0.48 the most hazardous 𝘙_max peak at roughly 1,000 kPa/°CA is caused, demonstrating that fastest is not always most damaging. Only the 1.38 s baseline keeps all combustion-severity metrics inside their reliability envelope. A feed-forward fuelling term scaled by the rate of manifold pressure change dP/dt is proposed to close the transient lambda gap; with physical implementation and experimental validation proposed as a future optimisation step. The results identify pressure-gradient management as the binding constraint for transient calibration of lean DI hydrogen engines. Description: Data availability: Data will be made available on request.

Intelligent Monitoring of Machining Processes using Gaussian Process Regression and On-Machine Comparator Measurement

Fri, 26 Jun 2026 00:00:00 GMT

Title: Intelligent Monitoring of Machining Processes using Gaussian Process Regression and On-Machine Comparator Measurement Authors: Papananias, Moschos; Noh, Yohan; Cheng, Kai Abstract: This paper presents an intelligent machining process monitoring approach with emphasis on On-Machine Comparator Measurement (OMCM) and the effect of remastering on dimensional accuracy. Comparator measurement applies the comparator principle by referencing each measurement to a calibrated master part. In this approach, a mastering procedure is first performed by measuring the calibrated master part to establish a reference. By directly comparing the test part with the master part under repeatability conditions, constant systematic errors in the measurement system are effectively cancelled when determining deviations from the master part. However, the accuracy of this method depends on the time interval between mastering and subsequent production measurements. An experimental study is conducted on a vertical milling centre using non-intrusive sensing. Gaussian Process Regression (GPR) is employed to model Coordinate Measuring Machine (CMM) measured diameter deviations and the associated uncertainty. OMCM is implemented, and the effect of remastering is discussed. The results demonstrate that measurement accuracy deteriorates when remastering is not performed prior to significant system drift, whereas timely remastering improves accuracy and reduces uncertainty, highlighting the critical role of remastering in maintaining measurement reliability with OMCM.

Molecular dynamics simulation of high slip flow of water confined between graphene nanochannels at experimentally accessible shear rates

Wed, 17 Jun 2026 00:00:00 GMT

Title: Molecular dynamics simulation of high slip flow of water confined between graphene nanochannels at experimentally accessible shear rates Authors: Civello, Carmelo Riccardo; Maffioli, Luca; Smith, Edward R; Ewen, James P; Daivis, Peter J; Dini, Daniele; Todd, BD Abstract: The transient time correlation function (TTCF) method has emerged as a powerful methodology for accurately probing systems at low shear rates. In the present study, TTCF was used to evaluate the shear rate dependence of the slip length in a high-slip system consisting of water confined between graphene walls at experimentally accessible shear rates, for which classical nonequilibrium molecular dynamics (NEMD) is unfeasible. The corresponding Navier friction coefficient was computed for all shear rates spanning six orders of magnitude and compared with the equilibrium limit. We report for the first time NEMD results obtained at experimentally accessible shear rates using the TTCF approach for a system that has attracted significant interest over the past decades. The slip length calculated with TTCF is in good agreement with previous equilibrium molecular dynamics simulations and experiments. Our aim here is to highlight the extraordinary power of TTCF, particularly for high-slip (low effective shear rate) systems, and to verify that equilibrium methods directly match NEMD measurements at experimentally accessible shear rates. Description: Data Availability: The data that support the findings of this study are available within the article and its supplementary material: https://ndownloader.figstatic.com/files/65223213 .

Extraction and linking of motivation, specification and structure of inventions for early design use

Fri, 23 Jun 2023 00:00:00 GMT

Title: Extraction and linking of motivation, specification and structure of inventions for early design use Authors: Jiang, Pingfei; Atherton, Mark; Sorce, Salvatore Abstract: Novel design creations often exist in the form of patents. It is well acknowledged that patents are a great source of design inspiration, therefore designers are encouraged to engage patents early in the design process. Studies of patent analysis have been carried out to benefit engineering design activities such as patent classification, technology forecasting, idea generation and emerging design-prior art comparison. However, the design intent behind inventions has received little attention in patent analysis. Designers can gain better design insight by looking at a patent from a systematic perspective starting from design intent to principal solutions. In this paper, an approach is proposed to extract and link the knowledge conveyed within patent descriptive sections to typical early engineering design stages, namely Motivation, Specification and Structure. This knowledge is then conceptualised into TRIZ engineering parameters and reconciled functional basis to enable cross-patent analysis. When compared to expert analysis, the proposed approach achieves an average of 63% accuracy with respect to Motivation, 56% with respect to Specification function and 44% with respect to Specification flow. Potential applications of such linking for early design use are then demonstrated through a prototype knowledge network.