Time Delay Measurements Research Articles

Timing Calibration of the Follow-up X-ray Telescope on board the EP satellite

Abstract The Follow-up X-ray Telescope (FXT) is one of the main scientific instruments on board the Einstein Probe (EP) astronomical satellite, which was launched in 2024 January. FXT consists of two Wolter I type nested telescopes (FXT-A and FXT-B) with a focal length of 1600 mm. The focal plane detector adopts PNCCD with 384×384 pixels within an image area of 28.8 mm × 28.8 mm. The timing mode of FXT serves as the primary operating mode for fast X-ray timing observations. To evaluate and validate the timing performance of FXT prior to launch, a comprehensive timing calibration was performed for FXT at the 100-m X-ray test facillity. By simulating various periodic Crab-like profiles using the Grid Controlled X-ray Tube (GCXT) with a pulsar simulation module, it was verified that the relative time accuracy of FXT surpasses 5×10-9. Furthermore, employing GCXT with a voltage pulse generation module allowed us to determine the time resolution of FXT-A and FXT-B as 45.6±2.7 μs and 47.1±2.8 μs, respectively. An absolute time calibration for FXT-B was carried out using GCXT and a time interval analyzer, revealing a measured time delay for FXT-B of 3.9±2.1 μs.

Advancing the C[formula omitted] low-temperature oxidation chemistry through species measurements in a rapid compression machine, Part A: 1-Butene

Alkene chemistry plays a crucial role in the autoignition and oxidation of larger hydrocarbons. Unlike its other isomers, 1-butene is characterized by a two-stage ignition process. Various previous studies of 1-butene oxidation have used experimental techniques, including the measurement of ignition delay times in rapid compression machines (RCM) and in shock tubes, the determination of flame velocities, and the measurement of species concentrations in flames and in jet-stirred reactors (JSR). JSR studies provide an important insight into intermediate species formation at low temperatures but are constrained to low pressures and/or highly diluted conditions. To bridge the gap between JSR and engine-relevant conditions, this study presents species concentration measurements during the oxidation of 1-butene at 733 K and 30 bar under stoichiometric ’air-like’ conditions in an RCM, complemented by IDT measurements in the temperature range of 680–910 K. We designed an innovative 2-valve sampling setup to reduce quantitative uncertainties and the time required for species measurements. Our results indicate that existing 1-butene models fail to accurately predict the IDTs and the formation of the key oxidation intermediates. In response, potential optimizations for an improved kinetic model based on NUIGMech1.3 are discussed. Rate parameters for predominantly fuel consumption pathways, along with other reactions and thermochemical properties in the Waddington mechanism, have been altered within expected uncertainty limits to reflect the experimentally observed IDTs and species concentrations of this study and other validation data from the literature. However, the refined model does not predict the formation of 2-ethenyloxirane and ethene, indicating a gap in our understanding of the chemistry of these components. Overall, this study demonstrates the importance of measuring intermediates under the same conditions as IDTs to accurately address deficiencies in current kinetic mechanisms, and represents the first phase of a comprehensive investigation advancing the understanding of C4 oxidation chemistry.Novelty and significance statementThe novelty of this research lies in the design of an innovative sampling system for RCM species measurements, lowering the time for experimental execution and the uncertainties of the measurements. This enabled first-time species measurements during the oxidation of butene isomers in an RCM at high pressure and low level of dilution, contributing to the refinement of the 1-butene sub-mechanism within the NUIGMech1.3 framework. This research contributes to the understanding of the oxidation of alkenes, an important class of intermediates in gasoline and biofuel combustion. It emphasizes the need to measure intermediate species at the same conditions as ignition delay times, which are essential for understanding oxidation pathways under engine-relevant conditions. This research is part of a broader investigation of C4 oxidation chemistry, along with our companion work on n-butane. The resulting kinetic model is capable of reproducing most of the available n-butane and 1-butene validation targets.

Ignition Delay Time Measurements of Substituted Phenol Additives in a Toluene Reference Fuel.

Using a rapid compression machine, fuel autoignition resistance can be quantified by the ignition delay time measurements of homogeneous mixtures. As the occurrence and intensity of knock in spark ignition engines are related to autoignition resistance, ignition delay time measurements give valuable insight into fundamental fuel combustion properties that can be used to predict undesirable combustion behavior. Therefore, the work presented in this paper aims to understand the autoignition resistance of a gasoline surrogate fuel and how it is affected by the addition of substituted phenol additives from ignition delay time measurements in a rapid compression machine. Six substituted phenols were tested: p-cresol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol. Lean and stoichiometric mixtures, as well as stoichiometric mixtures with N2 dilution, were studied at engine-relevant conditions of 20 bar between 700 and 950 K. It was found that most additives were able to lengthen the base fuel ignition delay time at high and low temperatures, but that the most effective had two methyl groups located adjacent to each other.

Dynamic analysis of a syphilis epidemic model with time delay and control measures

Dynamic analysis of a syphilis epidemic model with time delay and control measures

Distributed driving electric vehicle lateral stability control method considering time delay

This paper introduces a novel control method to address lateral stability challenge in distributed driving electric vehicles. By considering inherent time delay and unknown sensor measurement error generated from design, manufacturing, and external disturbances, the proposed approach achieves better robustness. Firstly, we establish a two-degree-of-freedom (2-DOF) dynamic model for lateral motion of an electric vehicle driven by in-wheel motors (EV-DIM). Based on this model, a control system considering time delay and unknown sensor measurement error is constructed. The control system incorporates a controller based on a dual domination gains observer, and its global asymptotic stability is rigorously proved by the Lyapunov method. Numerical simulations and co-simulations via CarSim and Simulink verify the method’s effectiveness. Compared to the sliding mode control, the proposed method shows better performance which indicates this approach promising for enhancing lateral stability of an electric vehicle.

Decoding microwave modulation transfer: The impact of dissipation through stochastic processes

AbstractAn anomalous transfer of modulation from a modulated microwave beam () to an unmodulated one () has been experimentally demonstrated through accurate delay time measurements. These results are analyzed according to two possible interpretations: one based on an electromagnetic approach as reported elsewhere, and the other based on a purely stochastic model. This latter model, made up of random zig‐zag paths, is the focus of the current paper. It is demonstrated that it is possible to obtain a plausible description of the experimental data.

Determination of acoustic properties of paraffin oil mixed with activated coal nanoparticles or SPAN80 using only BAW time delay measurement

An important aspect of controlling the properties of liquids relates to their use in modern engines powered by composite materials. In this context, controlling the properties of industrial fluids containing micro- and nanoscale particles is essential. Understanding the temperature-dependent behavior of fluid density and elasticity is crucial for proper engine operation. Seven physical parameters of pure paraffin oil, paraffin oil with varying concentrations of activated coal nanoparticles or sorbitane monooleate (SPAN 80) were simultaneously determined using only BAW time delay measurement in the single experimental run. This technique relies on propagating LBAW through the test fluid and measuring the time delay and amplitude of these waves at different temperatures. By calculating temperature coefficients for velocity, density, time delay, and expansion using well-established formulas the physical properties of fluids under study were determined. The frequency of the LBAW used in the experiment was 13 MHz. The length of the liquid sample in the propagation direction of LBAW was ∼ 5 mm. The experiments were carried out within a temperature range of −20 °C to +90 °C. The volume of the test sample was around 1 milliliter. The comparison of the physical properties of different suspensions under these conditions allows us to demonstrate the dependence of the measured properties on the type and composition of the medium tested.

Inverse distance ladder method for determining H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document} from angular diameter distances of time-delay lenses and supernova observations

Time-delay measurements from strong lensing systems combined with spectroscopic measurements of stellar kinematics in deflecting galaxies provide a natural way to infer absolute distances (lensing distances). This means that it can be used to anchor the relative distances of Type Ia supernovae (SNe Ia), and further infer the Hubble constant H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document} in a cosmological model-independent way, while avoiding the assumptions of curvature and the equation of state of dark energy. Indeed, observations based on gravitational lensing time delays can measure H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document} directly, but usually require assumptions about the specific cosmological models. Meanwhile, this method suffers the mass-sheet degeneracy obstacle. These factors may induce the bias on determination of H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document}. However, the inverse distance ladder method we use avoids these assumptions altogether. In this study, we seek for the Pantheon and Pantheon plus datasets and use Gaussian process regression to reconstruct the unanchored distance to match the distance at the redshift of the lens to determine H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document}, respectively. Based on the four H0LiCOW lenses, the unanchored distances reconstructed by combining the Pantheon and Pantheon plus datasets yielded H0=80.1-6.9+7.0km/s/Mpc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0=80.1^{+7.0}_{-6.9} \\mathrm {~km/s/Mpc}$$\\end{document} and H0=81.2-7.0+7.1km/s/Mpc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0=81.2^{+7.1}_{-7.0} \\mathrm {~km/s/Mpc}$$\\end{document} with 1σ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1 \\sigma $$\\end{document} observational uncertainty, respectively. All the lenses show the measured H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document} is in good agreement with the local measurement results reported by the SH0ES collaboration within ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim $$\\end{document}1.3σ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1.3 \\sigma $$\\end{document} confidence level.

Human-in-the-loop control of dynamics and robotics using augmented reality

Human-machine interaction (HMI) and human-robot interaction (HRI) offer innovative approaches for the analysis of structural dynamics both in laboratory and real-world scenarios. In vibratory experimentation, an external force is generated to evaluate dynamic responses of structures. One mode of generation is to use electrodynamic shakers. Sensors are attached to the structure to measure dynamic responses and can be deployed by robots. In post-disaster inspections robotic deployment ensures the safety of inspectors and requires control. If the interface between operators and the controls was augmented, then operators can visualize experiments, exciter levels, and define robot input while maintaining awareness of the area of interest. Robots can provide better aid to humans if control of the robot is: (1) quantified and presented to the human; and (2) conducted in real-time for human feedback. This research proposes using Augmented Reality (AR) to provide operators with sensor feedback and control for analysis of dynamic structures with robots. This method improves cognition by allowing the operator to maintain awareness of structures while adjusting conditions accordingly with the assistance of the new real-time interface. One interface application is developed to plot sensor data in addition to voltage, frequency, and duration controls for vibration simulations. Two more applications are developed following the same framework, one to control the position of a mediating robot and one to control the frequency of the robot's movement. The applications serve as a first-step approach investigating potential robotic sensor deployment in disaster assessment of structures. This paper presents the proposed model for the new vibratory control loop and then compares the new approach with a traditional method by measuring time delay in control input. The study also demonstrates that AR enhances time efficiency and accuracy in controlling robotic arm positions, matching actuator frequencies, and deploying sensors with minimal time delay.

Measurements of ignition delay time of gas-to-liquid (GTL) fuel blends

The ignition delay time (IDT) is a fundamental combustion parameter of any fuel, which has a direct impact on its combustion and exhaust emissions in diesel engines. In this research, a thorough experimental study was conducted to investigate the ignition delay of Gas-to-Liquid (GTL) fuel and its 50%–50 % blends with diesel under a wide range of operating conditions using a conventional shock tube apparatus. Simultaneously, a comprehensive chemical kinetic model, based on the well-established POLIMI mechanism, was developed to simulate the complex combustion chemistry of diesel, GTL, and their blends. Several loading pressures in the driver section ranging from 6 to 14 bar that results in reflected pressure of 8–16 bar, and equivalence ratios ranging from 0.5 to 1.3 as well as different initial temperatures have been examined. Calibration of the shock tube indicated that a driver gas tailoring technique was necessary to be used, which was conducted by adding a small ratio of either argon or nitrogen to helium to get an extended test time by 32 % with a good rapture pressure. IDT measurements showed that GTL has the shorter ignition delay time than that of diesel fuel for all conditions. The findings show that IDT measurements for GTL fuel has a shorter ignition delay time than that of diesel fuel for all conditions. Under stoichiometric conditions (ɸ = 1.0), IDT of the blended fuel was about 3 ms, very close to that of GTL at 975 K. However, at a temperature above 1000 K, the IDT of the three fuels were almost identical and ranging between 1 and 2 ms. At a temperature of 1100 K, the IDT of the blended fuel was 5.5 ms, almost a middle value between those of the pure diesel, 0.522 ms, and GTL fuel, 0.495 ms. The shortest IDT of the blended fuel was about 0.4 ms with the highest value of the reflected pressure of 14 bar, while the longest IDT was around 10 ms with the rich mixture at ɸ = 1.3. The study can add to the existing literature illustrating the behavior of GTL-diesel blend can affect IDT.

A shock-tube experimental and kinetic simulation study on the autoignition of methane at ultra-lean and lean conditions

Coalbed methane represents an important kind of natural gas resource in many countries. However, the low-concentration property of coalbed methane limits its applications. To gain insight into the combustion kinetics of coalbed methane and facilitate its combustion utilization, this work reports an experimental and kinetic simulation study on the autoignition properties of methane at ultra-lean and lean conditions. A shock-tube (ST) facility is used for ignition delay time (IDT) measurements with equivalence ratios at 0.5, 0.1, and 0.05 with pressure at 2 and 10 bar under the temperature ranging from 1320 to 1850 K. The measured IDTs can be correlated into a general Arrhenius expression, and the equivalence ratio effect on IDTs is then analyzed. Seven detailed chemical kinetic mechanisms are employed to predict the IDTs and statistical error indicators are used to evaluate their performance. Detailed kinetic analysis via sensitivity and reaction path analysis is performed to uncover the kinetic differences among the seven mechanisms. It is shown that some of the reaction paths only exist in the NUIGMech1.3 mechanism, while the other detailed mechanisms do not consider them. Reaction path analysis indicates that the reactions related to O2, OH and O species become more important compared to the reactions involving CH3 and H radicals as the equivalence ratio decreases from lean to ultra-lean conditions. Detailed chemical kinetics analysis is also conducted to demonstrate the uncertainty of key reactions. The present work should be valuable to gain insight into the methane ignition characteristics and to facilitate kinetic mechanism optimization of methane combustion.

Single-shot measurement of a laser waveform using plasma fluorescence in ambient air.

The temporal characterization of a laser pulse is an important task in studying ultrafast laser-matter interactions. It is ideal to measure the temporal profile of the laser pulse with a single laser shot when the repetition rate is low or its interaction with matter is unstable. Here we report a new approach for the single-shot temporal characterization of a laser pulse, based on the TIPTOE (tunneling ionization with a perturbation of the time-domain observation of an electric field) method. The waveform of the laser pulse is reconstructed from the intensity modulation of plasma fluorescence emission. The result of the single-shot measurement is compared with the time-delay scanning TIPTOE measurements, supporting the validity of the single-shot measurement.

Relative reactivity of methyl anisole isomers: An experimental and kinetic modelling study

Due to the current interest in biomass derived carbon neutral fuels and fuel additives for gasoline engines and to the growing need of understanding the fundamentals of gas phase combustion in the context of wildfires, this study investigates the combustion behavior of key components of biomass pyrolysis oils, namely the three methylanisole isomers (ortho-, meta- and para-methylanisole). Specifically, this study presents the first experimental ignition delay time measurements for such fuels using a shock tube and a rapid compression machine. Ignition experiments were carried out for stoichiometric fuel/air mixtures (φ = 1) at compressed pressure pc = 10 and 20 bar, covering a temperature range Tc = 880–1220 K. A kinetic model based on previous efforts in the area of oxygenated aromatic hydrocarbon fuels is proposed to reproduce and interpret the experimental findings, specifically focusing on capturing the observed different reactivity of the three isomers. To this aim, thermodynamic properties of primary intermediates and bond dissociation energies were calculated highlighting relevant differences originated from the relative position of the O–CH3 and –CH3 substituents. In addition, an isomerization pathway specific to the ortho isomer was theoretically investigated and found to motivate the observed higher reactivity with respect to the meta and para isomers

Prediction of dynamical systems from time-delayed measurements with self-intersections

In the context of predicting the behaviour of chaotic systems, Schroer, Sauer, Ott and Yorke conjectured in 1998 that if a dynamical system defined by a smooth diffeomorphism T of a Riemannian manifold X admits an attractor with a natural measure μ of information dimension smaller than k, then k time-delayed measurements of a one-dimensional observable h are generically sufficient for μ-almost sure prediction of future measurements of h. In a previous paper we established this conjecture in the setup of injective Lipschitz transformations T of a compact set X in Euclidean space with an ergodic T-invariant Borel probability measure μ. In this paper we prove the conjecture for all (also non-invertible) Lipschitz systems on compact sets with an arbitrary Borel probability measure, and establish an upper bound for the decay rate of the measure of the set of points where the prediction is subpar. This partially confirms a second conjecture by Schroer, Sauer, Ott and Yorke related to empirical prediction algorithms as well as algorithms estimating the dimension and number of required delayed measurements (the so-called embedding dimension) of an observed system. We also prove general time-delay prediction theorems for locally Lipschitz or Hölder systems on Borel sets in Euclidean space.

JWST Photometric Time-delay and Magnification Measurements for the Triply Imaged Type Ia “SN H0pe” at z = 1.78

Supernova (SN) SN H0pe is a gravitationally lensed, triply imaged, Type Ia SN (SN Ia) discovered in James Webb Space Telescope imaging of the PLCK G165.7+67.0 cluster of galaxies. Well-observed multiply imaged SNe provide a rare opportunity to constrain the Hubble constant (H 0), by measuring the relative time delay between the images and modeling the foreground mass distribution. SN H0pe is located at z = 1.783 and is the first SN Ia with sufficient light-curve sampling and long enough time delays for an H 0 inference. Here we present photometric time-delay measurements and SN properties of SN H0pe. Using JWST/NIRCam photometry, we measure time delays of Δt ab = −116.6−9.3+10.8 observer-frame days and Δt cb = −48.6−4.0+3.6 observer-frame days relative to the last image to arrive (image 2b; all uncertainties are 1σ), which corresponds to a ∼5.6% uncertainty contribution for H 0 assuming 70 km s−1 Mpc−1. We also constrain the absolute magnification of each image to μ a = 4.3−1.8+1.6 , μ b = 7.6−2.6+3.6 , μ c = 6.4−1.5+1.6 by comparing the observed peak near-IR magnitude of SN H0pe to the nonlensed population of SNe Ia.

Determining Cosmological-model-independent H 0 with Gravitationally Lensed Supernova Refsdal

The reappearance of supernova Refsdal with detailed modeling of the lens cluster allows us to measure the time-delay distance, which serves as a powerful tool to determine the Hubble constant (H 0). We give a cosmological-model-independent method to estimate H 0 through Gaussian process regression, using time-delay measurements from this lensed supernova in combination with supernova data from the Pantheon+ sample. Using eight mass models for the lens cluster, we infer H0=64.2−4.3+4.4kms−1Mpc−1 , and using two cluster models most consistent with the observations, we infer H0=66.3−3.6+3.8kms−1Mpc−1 . Our estimates of the value of H 0 are in 1σ agreement with the results assuming a flat ΛCDM model and the uncertainties are comparable. Our constraint results on H 0 from the eight lens models and the two lens models indicate 2σ and 1.8σ tensions with that estimated by Supernova H0 for the Equation of State, respectively. However, our median values of H 0 from the two sets of lens models show good consistency with H 0 inferred from Planck cosmic microwave background observations assuming a ΛCDM model within 1σ. We also find that our results for H 0 indicate 2σ deviations and 1.7σ deviations from the constraint results of H 0 using six time-delay quasars by H0LiCOW with the same analysis method.

Propagon boundary scattering relaxed via crystalline host on multiphase germanium telluride

The movement of heat through amorphous solids on an atomic level remains an outstanding question. Recent studies suggest that the primary thermal carrier in amorphous materials, propagons, essentially behaves like phonons. In this work, we provide experimental evidence that shows the interaction between propagons and phonons by utilizing the phase change chalcogenide germanium telluride. A series of ultra-long time-delay time-domain thermoreflectance measurements are used to analyze the scattering of vibrational thermal carriers at the boundaries of amorphous GeTe thin films relative to scattering across a crystalline-amorphous bilayer. We find that amorphous long wavelength propagons that would otherwise scatter can instead be hosted by a crystalline underlayer and its phonon population. This experimental evidence directly demonstrates propagon–phonon interactions in a clear experimental manner.

Real-Time Temperature Monitoring of Lithium Batteries Based on Ultrasonic Technology.

Electrochemical energy storage stations serve as an important means of load regulation, and their proportion has been increasing year by year. The temperature monitoring of lithium batteries necessitates heightened criteria. Ultrasonic thermometry, based on its noncontact measurement characteristics, is an ideal method for monitoring the internal temperature of lithium batteries. In this study, temperature and ultrasonic time delay measurement experiments were conducted on 18650 lithium batteries and laminated and wound lithium batteries to obtain the corresponding relationship between temperature and time delay and validate the temperature measurement for the same type of battery. The experimental results show that (1) the ultrasonic temperature measurement technique exhibits a relatively large error when used for 18650 Li-ion batteries under experimental conditions; (2) in the experiments on laminated and wound soft-pack lithium batteries, the relationship between temperature and time delay exhibits a nonlinear characteristic; and (3) under the experimental conditions, the ultrasonic temperature measurement errors were ±1.1 °C for stacked Li-ion batteries and ±1.4 °C for wound Li-ion batteries.

Ignition characteristics of ammonia-methanol blended fuel in a rapid compression machine

Ammonia has attracted wide attention in recent years as a carbon-free fuel. However, the low reactivity and combustion inertness of ammonia pose challenges to its applications in engines. Adding highly reactive fuels, such as renewable carbon–neutral methanol, offers a potential solution. To investigate the ignition characteristics of ammonia-methanol blended fuel, ignition delay time measurement and fast gas sampling under stoichiometric conditions with four ammonia blending ratios (20 % ammonia, A20; 40 % ammonia, A40; 80 % ammonia, A80; 95 % ammonia, A95) were carried out on a rapid compression machine under engine-relevant conditions. The effective thermodynamic conditions were 15–25 bar and 810–970 K. The concentrations of fuels NH3, CH3OH, and intermediate species N2O, CO, as well as products N2, CO2 were detected using gas chromatography. Chemical analysis was performed based on simulations using five ammonia-methanol reaction mechanisms. The ignition delay time results showed that the addition of methanol shortened the ignition delay time, with only a little change in ignition delay time beyond 20 % methanol content. Methanol significantly promoted the production of OH radical, leading to the enhancement of the overall mixture reactivity. The sampling results showed different consumption patterns of ammonia and methanol during the ignition process at different mixing ratios. For A80, methanol was consumed from the early stage of the ignition process, while ammonia consumption was negligible in the early stage. Conversely, for A95, ammonia consumption began in the early stage. This suggests that methanol and its intermediate species inhibited the consumption of ammonia, however, ammonia promoted the consumption of methanol. Chemical analysis further revealed that the inhibitory effect of methanol on ammonia consumption was weakened with the decrease of methanol proportion.

Cosmography with supernova Refsdal through time-delay cluster lensing: Independent measurements of the Hubble constant and geometry of the Universe

We present new measurements of the values of the Hubble constant, matter density, dark energy density, and dark energy density equation-of-state (EoS) parameters. These results have been obtained from a full strong-lensing analysis of the observed positions of 89 multiple images and 4 measured time delays of the supernova (SN) Refsdal in the Hubble Frontier Fields galaxy cluster MACS J1149.5+2223. By strictly following the identical modelling methodology (as done in our previous work undertaken before time delays were available), our cosmographic measurements are essentially blind, based on the frozen procedure. Without using any priors from other cosmological experiments, in an open wCDM cosmological model and via our reference cluster mass model, we measure the following values: H0 = 65.1−3.4+3.5 km s−1 Mpc−1, ΩDE = 0.76−0.10+0.15, and w = −0.92−0.21+0.15 (at the 68.3% confidence level). No other single cosmological probe has been able to simultaneously measure all these parameters. Remarkably, our estimated values of the cosmological parameters, in particular that of H0, are very robust and do not significantly depend on the assumed cosmological model or the cluster mass modelling details. The latter aspect introduces systematic uncertainties on the values of H0 and w, which are found to be largely subdominant compared to the statistical errors. The results of this study demonstrate that the combination of time delays in lens galaxy clusters with extensive photometric and spectroscopic information offers a novel and competitive cosmological tool.