Time Delay Research Articles

Negative feedback systems for modelling NF-κB transcription factor oscillatory activity.

Low-dimensional negative feedback systems (NFSs) were developed within a signal flow model to describe the oscillatory activities of NF-κB caused by interactions with its inhibitor IκBα. The NFSs were established as 3rd- and 4th-order linear systems containing unperturbed and perturbed negative feedback (NF) loops with constant or time-varying NF strengths and a feed-forward loop. NF-related analytical solutions to the NFSs representing the time courses of NF-κB and IκBα were determined and their exact mathematical relationship was found. The NFS's parameters were determined to fit the experimental time courses of NF-κB in TNF-α-stimulated embryonic fibroblasts, rela-/- embryonic fibroblasts reconstituted with RelA, C9L cells, GFP-p65 knock-in embryonic fibroblasts and embryogenic fibroblasts lacking Iκβ and IκBε, LPS-stimulated IC-21 macrophages treated or not with DCPA, and anti-IgM-stimulated DT40 B-lymphocytes. The unperturbed and perturbed NFSs describing the above biosystems generated isochronous and non-isochronous solutions, depending on a constant or time-varying NF strength, respectively. The oscillation period of the NF-coupled solutions, the phase difference between them and the time delays in the appearance of cytoplasmic IκBα after stimulation of NF-κB were determined. A significant divergence between the IκBα solutions to the NFSs and the IκBα experimental courses led to a rejection of the NF coupling between NF-κB and IκBα in the above biosystems. It was shown that neither the linearity nor the low dimensionality of the NFSs altered the NF relationship and the divergence between the IκBα solutions to the NFS and IκBα experimental time courses. Although the NF relationship between IκBα and NF-κB was not confirmed in all the experimental data analyzed, delayed negative feedback was found in some cases.

МЕТОД КОДУВАННЯ ВІДЕОДАНИХ В СПЕКТРАЛЬНО- ПАРАМЕТРИЧНОМУ ПРОСТОРІ

It is shown that the development of modern infocommunication systems is followed by the trend of widespread use of wireless technologies. The level of intellectualization of the protocols of their functioning is increasing. Accordingly, the characteristics of wireless infocommunication technologies for data transmission are increasing. This contributes to their use for data transmission from remote robotic platforms in the process of information support for the functioning of critical infrastructure. It is substantiated that the transmission of video data with the required level of bit intensity on the basis of existing on-board telecommunication technologies is organized under conditions of significant time delays. Consequently, the level of efficiency of information delivery is lost. On the other hand, there are losses in the reliability of video information. It is argued that the option for solving the problem lies in the further development of technologies for encoding video information streams. The most common platform is the JPEG format. However, the city has disadvantages. They refer to the loss of compression levels in the event of a reduction in the potential for detecting psychovisual addictions. The article substantiates an approach for improvement, which consists in the use of an adapted coding technology in the spectral-parametric space. This approach consists in detecting subbands in spectral arrays and their subsequent parameterization with the formation of structural components at a significant level and length. Further processing is proposed to be carried out taking into account the informativeness of segments and reducing the amount of structural redundancy. An approach for constructing a technology for compression of spectral arrays with the detection of spectral sub-bands is substantiated. A model has been created to find the amount of information for transformed segments in the spectral-parametric space. This takes into account the available amount of redundancy, which is established by determining the constraints on the values of structural components. A method for encoding segments in spectral-parametric description has been developed. The main basic components of the method relate to the processing of sets of two-component structural-parametric components, taking into account the peculiarities of their content depending on the presence of quantization processes.

AN EFFICIENT VLSI IMPLEMENTATION OF EDGE DETECTION OF IMAGES

Edge detection is a fundamental process in image processing with significant implications across multiple domains. Within the realm of object detection, the accurate delineation of image perimeters forms the bedrock for subsequent analysis. In this study, we present an optimized Laplacian Edge Detection algorithm tailored for efficient implementation in hardware.Leveraging approximation methodologies and strategic pipelining, we streamline complex operations, thereby reducing latency and resource consumption. Our implementation, realized through the Verilog Hardware Description Language (VHDL), stands as a testament to the efficacy of our approach. Through rigorous optimization and meticulous comparison with conventional Sobel edge detection, we demonstrate superior performance metrics, including enhanced Area utilization, reduced Time Delay, and improved Power Efficiency. This work underscores the importance of methodological refinement and technological innovation in advancing edge detection techniques for practical applications. Keywords: Laplacian, Sobel, Kernel, Pixel range, Area, Power

Joint prediction method for strip thickness and flatness in hot strip rolling process: A combined multi-indicator Transformer with embedded sliding window

Thickness and flatness are important quality indicators for strip. It is important that the rapid and accurate prediction of the exit thickness and flatness for the optimal control of the hot strip rolling process. Due to the fast and long rolling process, there are time delays, non-linearity and strong coupling among the variables, which cause difficulties in the establishment of prediction models. In this paper, the variables related to thickness and flatness are selected by analyzing the rolling process mechanism and data. Based on the data related to the rolling quality, a rolling exit thickness and flatness joint prediction model combined multi-indicator Transformer with embedded sliding window (SW-MTrans) is proposed. First, a sliding window is embedded into the input layer of the model in order to address the effect of the time delay among variables. Then a Transformer network is improved to achieve accurate prediction of thickness and flatness simultaneously. It is verified that the proposed method can predict the thickness and flatness at the same time with higher prediction accuracy and generalization ability compared with other methods through actual production data. The mean absolute error (MAE) for thickness prediction was reduced by 19.37% and MAE for flatness prediction was reduced by 14.03% compared to the existing prediction model.

Do traffic flow states follow Markov properties? A high-order spatiotemporal traffic state reconstruction approach for traffic prediction and imputation

Assessing traffic states accurately is challenging due to the complex, high-dimensional, and nonlinear nature of traffic systems. This study introduces the innovative High-Order Spatiotemporal Traffic State Reconstruction (HOSTSR) algorithm, designed to track and predict traffic flow dynamics effectively. It combines phase space reconstruction with time delays and high-order neighborhood concepts from graph theory to improve traffic state assessments' accuracy. The algorithm's effectiveness is validated using chi-square tests and the Chapman-Kolmogorov equation to confirm the Markovian properties of traffic flows. A lean autoencoder, informed by prior Markov knowledge of traffic states, is developed for mapping traffic states to real traffic data, proving highly effective for traffic data imputation due to the Markov model's memoryless property. Experimental results from the PeMSD04 and PeMSD08 datasets show that HOSTSR outperforms traditional state reconstruction methods based on delayed coordinate embedding in predicting future traffic flow state based on four key metrics. The autoencoder framework, guided by prior Markov knowledge, shows significant advantages in addressing traffic data gaps in different cases over six baseline models. Gradient sensitivity analysis further evaluates the impact of prior knowledge on improving the autoencoder's interpretability for interpolation efforts.

Role of supplementary cementiteous materials in mitigating heat of hydration in mass concrete elements

Concrete’s heat of hydration can cause wide restraint cracks, delayed ettringite formation and low strength. The heat of hydration in concrete poses significant challenges in the construction industry particularly in mass concrete elements. Addressing these challenges, the utilization of supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GBFS) in concrete has been extensively studied for their individual contributions in modifying the heat of hydration. However, the comparative effectiveness of FA and GBFS, as well as the implications of their combined use in a ternary blend mix, remain underexplored. This study aims to bridge this gap by investigating the heat evolution profiles of concrete blends incorporating varying proportions of FA, GBFS, and general Portland cement (GPC). Through a series of semi-adiabatic tests, the study evaluates the hydration kinetics, maximum temperature rise, and time delay to peak temperature for binary and ternary mixes. The findings suggest that while individual SCMs like FA and GBFS offer distinct thermal benefits, their combined use in a ternary blend presents a synergistic effect, optimizing heat management in concrete. In essence, this study not only underlines the potential of ternary blends in enhancing concrete's thermal performance but also emphasizes their role in promoting sustainable and resilient construction practices.

Dynamics of a New Delayed Glucose–Insulin Model with Obesity

In this work, a new glucose–insulin model incorporating time delay and obesity is developed to gain insights of its dynamical mechanisms. Through the method of multiple scales, we theoretically demonstrate that time delay can drive the system to yield Hopf bifurcation, thereby producing oscillating solutions that are consistent with the simulation results. Moreover, obesity changes the level of glucose, but cannot induce oscillations. In particular, it is found that under the combined effect of obesity and time delay, obesity delays the appearance of Hopf bifurcation which is induced by time delay. Results show that a low calorie diet can achieve therapeutic effects including reducing blood glucose fluctuations and insulin resistance, which can be used as an adjuvant for the treatment of diabetes. In addition, our results indicate that the delay, together with an optimal rate of model parameters can cause a variety of dynamics and induce glucose oscillations. The result obtained in this paper may help to better understand the obesity, diabetes, and the interaction between glucose and insulin, so that control strategies can be designed to better regulate blood glucose levels and fluctuations and mitigate the occurrence of type-2 diabetes.

TIME TO SURGERY FOR NECK OF FEMUR FRACTURES IN SOUTHLAND FOR PATIENTS PRESENTING DIRECTLY TO A REFERRAL HOSPITAL VERSUS TRANSFERRAL FROM PERIPHERAL HOSPITAL: A MATCHED COHORT STUDY

IntroductionThe Te Whatu Ora Southern catchment area covers the largest geographical region in New Zealand (over 62,000 km2) creating logistical challenges in providing timely access to emergency neck of femur (NOF) fracture surgery. Current Australian and New Zealand guidelines recommend that NoF surgery be performed within 48 hours of presentation. The purpose of this study was to compare the outcomes for patients with NoF fractures who present directly to a referral hospital (Southland Hospital) compared to those are transferred from rural peripheral centres.MethodsA retrospective cohort study identified 79 patients with NoF who were transferred from rural peripheral centres to a referral hospital for operative management between January 2011 to December 2020. This cohort was matched 1:1 by age and sex to patients with NoF who presently directly to the referral hospital over the same period. The primary outcome was to compare time to surgery between the groups and secondary outcomes were to compare length of hospital stay, complication rates and mortality rates at 30-days and 1-year.ResultsThe mean delay in transfer time from peripheral centres was 11.5 ± 6.4 h. The mean time to surgery was higher, but not significantly different (p=0.155), for patients transferred from peripheral centres compared to patients presenting directly to the referral hospital (30.7 ± 16.5 h vs. 26.8 ± 17.2 h, respectively). However, rates of surgery within 48 h were similar between the patients transferred from peripheral centres and patients presenting directly to the referral hospital (8.8% vs 7.6%, p>0.999). There were no significant differences in complication rates, length of stay or 30-day or 1-year mortality between the groups.Discussion and ConclusionSignificant delays in transfer from peripheral centres to the referral hospital were identified, averaging 11.5 h. There was a strong trend towards increased time to surgery for patients transferred from peripheral centres. Early transfer of patients with NoF to a referral hospital should continue to be made a high priority.

Establishing a telehealth model addressing paediatric sleep health in remote and rural Northern Territory Australia: Overcoming the distance barrier.

This study examined the outcomes of a telehealth model for sleep health assessment among Indigenous and non-Indigenous children residing in remote and regional communities at the Top End Northern Territory (NT) of Australia. Video telehealth consultation, that included clinical history and relevant physical findings assessed virtually with an interstate paediatric sleep physician was conducted remotely. Polysomnography (PSG) and therapeutic interventions were carried out locally at Darwin, NT. The study participants were children referred between 2015 and 2020. Of the total 812 children referred for sleep assessment, 699 underwent a diagnostic PSG. The majority of patients were female (63%), non-Indigenous (81%) and resided in outer regional areas (88%). Indigenous children were significantly older and resided in remote or very remote locations (22% vs. 10%). Referral patterns differed according to locality and Indigenous status - (non-Indigenous via private (53%), Indigenous via public system (35%)). Receipt of referrals to initial consultation was a median of 16 days and 4 weeks from consult to PSG. Remote children had slightly longer time delay between the referral and initial consult (32 vs. 15 days). Fifty one percent were diagnosed to have OSA, 27% underwent adenotonsillectomy and 2% were prescribed with CPAP therapy. This study has demonstrated that a telehealth model can be an effective way in overcoming logistical barriers and in providing sleep health services to children in remote and regional Australia. Further innovative efforts are needed to improve the service model and expand the reach for vulnerable children in very remote communities.

Comparative Study of EMD based Modelling Techniques for Improved Agricultural Price Forecasting

Forecasting agricultural commodity prices is regarded as a challenging task due to its non-linear and non-stationary nature. As agriculture productionis highly reliant on various biological and agro-meteorological factors, traditional smoothing techniques as well as statistical models often fail tomodel such series satisfactorily. To capture such complex patterns effectively, different data-driven and self-adaptive techniques have been developedtime-to-time. Against this backdrop, in this paper, we have assessed the suitability of empirical mode decomposition (EMD)-based neural network andsupport vector regression (SVR) approaches for forecasting wholesale prices of three major potato markets namely, Agra, Bangalore, and Mumbai.As the benchmark models, autoregressive integrated moving average (ARIMA), time delay neural network (TDNN) and SVR models have beenemployed for the comparative evaluation. The experimental results clearly reveal the comparative superiority of the EMD-SVR model for the Agraand Bangalore markets and the EMD-TDNN model for the Mumbai market in terms of root mean squared error values and turning point predictions.Moreover, all the EMD-based models have performed better than the other competing models.

Non-Markovian Feedback Retrial Queue with Two Types of Customers and Delayed Repair Under Bernoulli Working Vacation

This paper deals with an M/G/1 feedback retrial G-queue and delayed repair incorporating Bernoulli working vacation. Arrivals of both favorable and unfavorable consumers are two independent Poisson processes. The server is subjected to breakdown during the regular busy period due to the arrival of unfavorable customers and then the server will be down for a short period of time. Further, the concept of delay time is also discussed. After the fulfillment of regular service, the dissatisfied consumer may re-join the orbit to receive another service as a feedback consumer. During the working vacation period, the server provides the service to consumers at a reduced rate. By applying the supplementary variable technique (SVT), we have analyzed the steady-state probability generating function (PGF) for the system size and orbit size. In addition, we have presented the system performance, reliability indicators, and stochastic decomposition property. Finally, we provided numerical examples to illustrate our model’s mathematical results.

Improvement of Teach Protocol for Enhancing Features of WSN

. Wireless Sensor Network (WSN) has several applications such as military, industry. and environment. The importance of WSNs in current applications makes the WSN technology highly relevant and significant to the field of communication and computing. However, WSN's performance deals with number of challenges. Energy consumption is the most considerable because nodes use energy to collect, treat, and send data, but they have restricted energy- For this reason. numerous efficient energy routing protocols have been dev eloped to save the consumption or power. Low energy adaptive clustering hierarchy (LEACH) is considered the most attractive one in WSNs, in this projects we evaluate the LEACH approach effectiveness in the cluster-head (CHJ choosing and in data transmission, then we propose an enhanced protocol. proposed algorithm aims to improve energy Consumption and prolong the lifetime of WSN through selecting CHs depending on the remaining power, balancing the number of nodes in clusters. determining abandoned nudes in order to send their data to the sink. Then CHs choose the optimal path to reach the sink, we propose a new approach to achieve better enhancement of WSN in terms of network lifetime and data transmission time represented by reducing the packet delay time. Then, we compare the simulated result of the proposed algorithm with the basic LEACH protocol.

Challenges in downstream dam passage and the effect of dam removal on Atlantic salmon (Salmo salar) smolt migrations.

Migration is critical for life-cycle completion in diadromous fish species. River connectivity is vital in facilitating these large-scale movement events, but the extent of present-day river fragmentation can interfere with these migrations. Fish passage solutions (FPSs) are commonly implemented with the aim of improving river connectivity. In our study, we investigated the performance of two types of FPSs, spill regimes and complete dam removal, on Atlantic salmon (Salmo salar) smolt migrations. We used acoustic telemetry to monitor migration behavior and passage success of 120 wild smolts released in three different groups/sites: one group with two dams to pass to reach the river mouth, a second group with one dam to pass, and a control group without any barriers to pass (upstream of a recently removed hydroelectric dam). Smolt passage probabilities were similar for the two studied dams (87% and 86%) but showed variation in path choice, delay times, and loss rates. Passage success was influenced by several factors, such as body size, diel period, and water temperature, but not flow. Cumulative passage success to the river mouth was 61%, with most individuals being lost within lentic river stretches, either in the forebays of hydroelectric power stations or in naturally wide river stretches. Within the recently rehabilitated river sections (post dam removal), passage speeds were significantly faster than all other sections of the river (post-rehabilitation x¯ = 56.1 km/day) with significantly faster speeds compared to pre-rehabilitation (pre-x¯ = 28.0 km/day). Our findings provide valuable information on the benefits of dam removal and highlight the need for further rehabilitation measures in upriver reaches where barriers still affect downstream passage.

Study of Urban Arterial Road Off-Ramp Configuration in Highway Municipal Reconstruction

To reduce traffic congestion and improve the overall traffic capacity of roads, the municipal reconstruction of arterial roads from high-grade highways often involves setting up auxiliary roads on both sides of the road. This paper analyzes the existing methods of determining the configuration of urban arterial road off-ramps and proposes a novel design method, includes adding a “waiting for merging” section. Based on the traffic flow characteristics of the main roads, auxiliary roads, as well as off-ramps, second-stage deceleration theory and the insertable gap theory are applied. Considering the worst-case of diverted vehicles, a calculation model for the length of the urban arterial road off-ramps is proposed and utilized to calculate the advisory values for each segment of the off-ramps. Taking the reconstruction of an expressway in Hubei Province, China, as a case study, Vissim traffic simulation software was used to compare the proposed method with the traditional design method under four different traffic volumes. The results show that the proposed design method greatly improves the overall traffic capacity of roads compared with the traditional method, with a reduction of approximately 40% and 60% in delay time and queue length for the overall traffic, respectively. Furthermore, the research results can provide direct and effective design solutions and a basis for decision-making for setting the length of main and auxiliary road off-ramps.

Women with acute heart failure receive help from a cardiologist faster than men-gender disparities in acute heart failure

Abstract Funding Acknowledgements None. Introduction Acute heart failure (AHF) is a life-threatening condition that requires quick diagnosis and immediate treatment. Emergency Department (ED) is a major stage for hospitalized patients with AHF. Recent studies have highlighted that the efficacy of any intervention and treatment may be time dependent. Purpose The aim of the study was to analyze the management of patients with AHF depending on gender before treatment in Intensive Cardiac Care Unit (ICCU). Materials and methods In the period from 06/2019 to 01/2021, 767 patients with a diagnosis of acute heart failure (AHF) were urgently admitted to the ED. The most severely unwell 122 patients diagnosed with AHF required treatment in the ICCU . The time of onset of AHF symptoms (SYMPTOMS), first medical contact (FMC) and the time of cardiologist consultation (CC) in the Emergency Department were determined. Results In the study group of 767 patients with AHF presenting to the ED, women constituted 37%.They were less likely to be admitted to the Cardiology Department with a diagnosis of AHF than men (29.5% versus 40.2%) however they died more often in the ED (6.0% versus 2.7%). Among the 122 patients with AHF treated in the ICCU, the majority were men (72%), the mean age was 68 years and the median LVEF = 30% [IQR 20-38%]. In both sexes, the phe.notype of acute decompensated heart failure predominated (68% in women and 82% in men), although acute pulmonary oedema was slightly more common in women (26% versus 15% in men). Women contacted a doctor or called an ambulance faster than men (median time SYMPTOMS to FMC shorter by 1.6 days) and the time from FMC to consultation with a cardiologist was shorter (median time SYMPTOMS to FMC shorter by 0.17th day). Consequently, the delay time from the onset of symptoms to cardiology consultation was twice shorter in women than in men: 3.1 [IQR 0.3-8.4] days vesus 6.9 [IQR1.3-15.3], p=0.05. Conclusion Women with acute heart failure treated in the Intensive Cardiac Care Unit see a doctor faster and also receive specialist help from a cardiologist faster than men.

High-harmonic spin-shearing interferometry for spatially resolved EUV magneto-optical spectroscopy

We present a method for achieving hyperspectral magnetic imaging in the extreme ultraviolet (EUV) region based on high-harmonic generation (HHG). By interfering two mutually coherent orthogonally-polarized and laterally-sheared HHG sources, we create an EUV illumination beam with spatially-dependent ellipticity. By placing a magnetic sample in the beamline and sweeping the relative time delay between the two sources, we record a spatially resolved interferogram that is sensitive to the EUV magnetic circular dichroism of the sample. This image contains the spatially-resolved magneto-optical response of the sample at each harmonic order, and can be used to measure the magnetic properties of spatially inhomogeneous magnetic samples.

Impact of misdiagnosis on the treatment and prognosis of acute aortic syndrome

Abstract Funding Acknowledgements None. Introduction Acute aortic syndrome (AAS) embraces a spectrum of pathologies with relatively low prevalence but associated with high mortality. The clinical presentation of AAS is highly variable and the differential diagnosis with other much more common diseases such as myocardial infarction (AMI) or pulmonary embolism (PE) is often difficult to achieve. AAS detection requires a high index of suspicion and the delay in diagnosis is associated with increased morbidity and mortality. Purpose The aim of this study is to characterize the diagnostic approach to AAS patients in the emergency department (ED) and to study the impact of the initial diagnostic suspicion on the treatment and prognosis of patients with AAS. Methods The "Aorta Code" is an inter-hospital and interdisciplinary care protocol for the management of patients with AAS in a 4-Hospital network. Patients with AAS were prospectively and consecutively collected from 2019 to 2022. The sample was classified into two groups according to whether the initial suspicion was AAA or another clinical entity. The diagnosis of AAS was established by computed tomography in all patients. Time, clinical, treatment and prognostic variables were analyzed. Results A total of 113 patients with AAS were included. Of them, only 38% (34) were initially suspected of having an AAS (Figure). AMI and PE were the initial diagnosis in 34% of patients (Figure). There were no significant differences in age, history of hypertension or other cardiovascular risk factors between the groups (table). Anterior chest pain was more frequent in the "AAS-suspicion" group. The diagnostic time delay was longer in patients with initial misdiagnosis (table). Patients with type A AAS with initial misdiagnosis underwent surgery in a lower proportion (table). Although the differences were not significant, patients with initial misdiagnosis had more postoperative complications and higher mortality. Conclusion It is essential to maintain a high index of diagnostic suspicion for AAS in the ED. Initial misdiagnosis is associated with a delayed diagnosis, delayed surgical treatment and a lower rate of surgery. In addition, although it is a small sample size, this group of patients had more postoperative complications and higher mortality.

Deformation Analysis and Prediction of a High-Speed Railway Suspension Bridge under Multi-Load Coupling

High-speed railway suspension bridges (HSRSBs) have been constructed with the new advancements in technology. The deformation prediction for HSRSBs is essential to their safety and maintenance. The conventional prediction methods are developed for bridges without high-speed railway. Different factors, including temperature (TEMP), time delay compensation (TDC), train live load (TLL), are considered in these methods. However, the train side (TS) and train instantaneous position (TIP) have a significant impact on deformation for HSRSBs, and they are not used in the prediction. More importantly, the coupling issue among different factors is so significant that it cannot be neglected. In this study, we propose a deformation prediction model based on a backpropagation (BP) neural network. This model uses different factors as model input, including TEMP, TDC, TLL, TS, and TIP. The coupling issue is addressed by using the new model. The new model was evaluated using a dataset of 10-day field measurements. It achieves a mean absolute error (MAE) of 8.81 mm, a mean relative error (MRE) of 9.82%, and coefficient of determination (R2) of 0.94. The new model will provide high-precision prediction for deformation and will be used in the development of an early warning system.

Thermal shock triggers microexplosion combustion in graded fuel and oxidizer encapsulation microspheres with improved combustion efficiency

The combustion agglomeration of aluminum (Al) and the long heat and mass transfer distance between Al and oxidizer cause serious two-phase flow loss and slag accumulation in the engine of solid propellants. Here, we present an effective strategy by in-situ encapsulating graded nano-aluminum (nAl) and micron-aluminum (μAl) in ammonium perchlorate (AP) simultaneously by using hydroxymethyl cellulose (HMC) as adhesive and constructing a compact coupling fuel oxidizer complex high-energy microsphere (μAl/nAl@AP/HMC) to enhance the energy release efficiency and combustion efficiency. Compared with physical mixture (PM), the ignition delay time and combustion time of μAl/nAl@AP/HMC microspheres are reduced by 69.58 % and 69.87 %, owing to the decomposition process control of AP through the adsorption and spatial constraint effect on the interface between metal fuels and oxidizer. Furthermore, the nAl embedded in the AP surface forms a hot spot around the μAl to promote the combustion reaction, thereby shortening the cavitation threshold and tensile limit time of μAl and accelerating the occurrence of microexplosion. Microexplosion effect in μAl/nAl@AP/HMC microsphere significantly weakens combustion agglomeration and improves combustion efficiency and energy release efficiency by sharp shrinkage of combustion condensation products, which addresses the challenges on energy output and combustion efficiency in high-density solid propellants.

Experimental and kinetic modeling study of 1,3,5-trimethylbenzene oxidation at elevated pressure

This work presents the experimental and modeling results of 1,3,5-trimethylbenzene (T135MB) oxidation in a jet-stirred reactor at equivalence ratios (Φ) of 0.4 and 2.0, temperature range of 660–1020 K and pressure of 12.0 atm. 5 aromatic compounds, 5 oxygenated species and 6 light hydrocarbons were identified and quantified using GC and GC-MS. Compared with previous oxidation studies, 1-ethyl-3,5-dimethylbenzene, 3,5-dimethylbenzaldehyde, 3,5-dimethylphenol, ethylene and acetylene were newly detected. A detailed chemical kinetic model involving 911 species and 5370 reactions was developed and validated against experimental results of T135MB oxidation speciation at jet-stirred reactor and shock tube, laminar burning velocities and ignition delay times. Rate-of-production analysis shows that the dominant consumption channel of T135MB is H-abstraction by OH radicals on methyl sites, and 3,5-dimethylbenzaldehyde is a key intermediate in the oxidation of T135MB. Compared with atmospheric pressure, sharp consumption of T135MB was observed (the fuel conversion rate changes from 25 % at 838 K to 95 % at 839 K) under fuel-lean condition at 12 atm, which results from the rapid growth of OH radicals controlled by H2O2(+M) = 2OH(+M). Sensitivity analysis reveals that H-abstraction reactions of T135MB by OH and H on methyl sites are the most inhibiting reactions at Φ = 0.4 and 2.0, respectively, when T135MB conversion rate is 25 %. However, these two reactions become promoting at 95 % T135MB conversion. The H-abstraction reaction of T135MB with O2 on methyl sites is the most promoting at 25 % T135MB conversion, shifting to an inhibiting reaction at 95 % conversion.Novelty and significance statement: The novelty of this research is that high-pressure and low-temperature oxidation experiment of T135MB covering both fuel-lean and fuel-rich conditions was first reported in this work with abundant intermediates information. Rapid consumption of T135MB under fuel-lean condition was observed, and new intermediates such as 3,5-dimethylbenzaldehyde were detected which plays an important role in the fuel conversion. Additionally, a comprehensive kinetic model for T135MB was developed, which well predicts speciation, ignition delay times and laminar flame speeds under wide range of conditions. It is significant because the high pressure data is very important for the model validation since it is more close to the real engine-operating conditions. Moreover, the model provides insight on the high pressure chemical kinetics of the aviation surrogate fuel consumption and deepens the understanding of low-temperature oxidation of alkyl aromatics.