| 1. |
- Cheng, Haibo, et al.
(författare)
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ANN based Interwell Connectivity Analysis in Cyber-Physical Petroleum Systems
- 2019
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Ingår i: Proceedings. - : IEEE. ; , s. 199-205
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In cyber-physical petroleum systems (CPPS), accurate estimation of interwell connectivity is an important process to know reservoir properties comprehensively, determine water injection rate scientifically, and enhance oil recovery effectively for oil and gas (O&G) field. In this study, an artificial neural network (ANN) based analysis method is proposed to estimate interwell connectivity. The generated neural network is used to define the mapping function between production wells and surrounding injection wells based on the historical water injection and liquid production data. Finally, the proposed method is applied to a synthetic reservoir model. Experimental results show that ANN based approach is an efficient method for analyzing interwell connectivity.
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| 2. |
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| 3. |
- Cheng, Haibo, et al.
(författare)
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Automatic Recognition of Sucker-Rod Pumping System Working Conditions Using Dynamometer Cards with Transfer Learning and SVM
- 2020
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 20:19
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Tidskriftsartikel (refereegranskat)abstract
- Sucker-rod pumping systems are the most widely applied artificial lift equipment in the oil and gas industry. Accurate and intelligent working condition recognition of pumping systems imposes major impacts on oilfield production benefits and efficiency. The shape of dynamometer card reflects the working conditions of sucker-rod pumping systems, and different conditions can be indicated by their typical card characteristics. In traditional identification methods, however, features are manually extracted based on specialist experience and domain knowledge. In this paper, an automatic fault diagnosis method is proposed to recognize the working conditions of sucker-rod pumping systems with massive dynamometer card data collected by sensors. Firstly, AlexNet-based transfer learning is adopted to automatically extract representative features from various dynamometer cards. Secondly, with the extracted features, error-correcting output codes model-based SVM is designed to identify the working conditions and improve the fault diagnosis accuracy and efficiency. The proposed AlexNet-SVM algorithm is validated against a real dataset from an oilfield. The results reveal that the proposed method reduces the need for human labor and improves the recognition accuracy.
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| 4. |
- Cheng, Haibo, et al.
(författare)
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Deep Learning-Based Prediction of Subsurface Oil Reservoir Pressure Using Spatio-Temporal Data
- 2023
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Ingår i: IECON 2023 - 49th Annual Conference of the IEEE Industrial Electronics Society. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Prediction of subsurface oil reservoir pressure are critical to hydrocarbon production. However, the accurate pressure estimation faces great challenges due to the complexity and uncertainty of reservoir. The underground seepage flow and petrophysical parameters (permeability and porosity) are important but difficult to measure in oilfield. Deep learning methods have been successfully used in reservoir engineering and oil & gas production process. In this study, the effective but inaccessible subsurface seepage fields are not used, only the spatial coordinates and temporal information are selected as model input to predict reservoir pressure. A stacked GRU-based deep learning model is proposed to map the relationship between spatio-temporal data and reservoir pressure. The proposed deep learning method is verified by using a three-dimensional reservoir model, and compared with commonly-used methods. The results show that the stacked GRU model has a better performance and higher accuracy than other deep learning or machine learning methods in pressure prediction.
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| 5. |
- Cheng, Haibo, et al.
(författare)
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LSTM Based EFAST Global Sensitivity Analysis for Interwell Connectivity Evaluation Using Injection and Production Fluctuation Data
- 2020
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Ingår i: IEEE Access. - : IEEE. - 2169-3536. ; 8, s. 67289-67299
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Tidskriftsartikel (refereegranskat)abstract
- In petroleum production system, interwell connectivity evaluation is a significant process to understand reservoir properties comprehensively, determine water injection rate scientifically, and enhance oil recovery effectively for oil and gas field. In this paper, a novel long short-term memory (LSTM) neural network based global sensitivity analysis (GSA) method is proposed to analyse injector-producer relationship. LSTM neural network is employed to build up the mapping relationship between production wells and surrounding injection wells using the massive historical injection and production fluctuation data of a synthetic reservoir model. Next, the extended Fourier amplitude sensitivity test (EFAST) based GSA approach is utilized to evaluate interwell connectivity on the basis of the generated LSTM model. Finally, the presented LSTM based EFAST sensitivity analysis method is applied to a benchmark test and a synthetic reservoir model. Experimental results show that the proposed technique is an efficient method for estimating interwell connectivity.
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| 6. |
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| 7. |
- Denil, Joachim, et al.
(författare)
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Model-Driven Engineering Approaches to Design Space Exploration
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- During the design and deployment of increasingly complex distributed embedded systems, engineers are challenged by a plethora of design choices. This often results in infeasible or sub-optimal solutions. In industry and academia, general and domain-specific optimization techniques are developed to explore the tradeoffs within these design spaces, though these techniques are usually not adapted for use within a Model- Driven Engineering (MDE) process. In this paper we propose to encode metaheuristics in transformation models as a general design exploration method. This is complemented by an MDE framework for combining different heterogeneous techniques at different abstraction layers using model transformations. Our approach results in the seamless integration of design space exploration in the MDE process. The proposed methods are applied on the deployment of an automotive embedded system, yielding a set of Pareto-optimal solutions.
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| 8. |
- Joshi, Prachi, et al.
(författare)
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Approaches for Assigning Offsets to Signals for Improving Frame Packing in CAN-FD
- 2020
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Ingår i: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0070 .- 1937-4151. ; 39, s. 1109-1122
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Tidskriftsartikel (refereegranskat)abstract
- Controller area network (CAN) is a widely used protocol that allows communication among electronic control units (ECUs) in automotive electronics. It was extended to CAN with flexible data-rate (CAN-FD) to meet the increasing demand for bandwidth generated by the growing number of features in modern automobiles. The signal-to-frame packing problem has been studied in the literature for both CAN and CAN-FD. In this paper, we propose and formulate the signal offset assignment problem (SOAP) in CAN-FD to improve the bus utilization during frame packing. We propose two algorithmic themes to solve SOAP and establish their worst case performance guarantees. The first is a general approximation framework (GAF) which can use any approximation algorithm for the makespan minimization problem (MMP) in multiprocessor systems. Its performance guarantee is the product of the performance guarantee of the MMP algorithm and the number of distinct periods in the frame. The second is a 2-D strip packing-based framework (2DSPF) which uses the bottom left fill algorithm for 2-D strip packing. The performance guarantee is 2G , where G is the minimum number of groups into which the set of signals can be partitioned so that the periods of the signals in the same group form a geometric series. The experimental results for GAF and 2DSPF indicate that by carefully assigning offsets for signals in frame packing schemes, one can achieve about 10.83% improvement in bus utilization in CAN-FD systems.
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| 9. |
- Joshi, Prachi, et al.
(författare)
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Offset Assignment to Signals for Improving Frame Packing in CAN-FD
- 2017
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Ingår i: 2017 IEEE REAL-TIME SYSTEMS SYMPOSIUM (RTSS). - : IEEE. - 9781538614143 ; , s. 167-177
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Konferensbidrag (refereegranskat)abstract
- Controller Area Network (CAN) is a widely used protocol that allows communication among Electronic Control Units (ECUs) in automotive electronics. It was extended to CAN-FD (CAN with Flexible Data-rate) to meet the increasing demand for bandwidth utilization caused by the growing number of features in modern automobiles. The signal-to-frame packing problem has been studied in literature for both CAN and CAN-FD. In this work, we propose and formulate, for the first time, the signal offset assignment problem (SOAP) in a frame in order to improve the bus bandwidth utilization. We prove that SOAP is NP-complete. We propose a general approximation framework (GAF) for SOAP which can use any approximation algorithm for the makespan minimization problem (MMP) in multiprocessor systems. We derive the performance guarantee provided by GAF as a function of the performance guarantee of the approximation algorithm for MMP and the number of signal periods in the frame. We demonstrate the efficacy of our approach through experiments using three different algorithms (two approximation algorithms and an integer linear programming formulation) for MMP in GAF. Our results indicate that by using offsets for signals in frame packing schemes, one can achieve about 10.54% improvement in bandwidth utilization (on a single bus) in CAN-FD systems.
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| 10. |
- Joshi, Prachi, et al.
(författare)
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The Multi-Domain Frame Packing Problem for CAN-FD
- 2017
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Ingår i: 29th Euromicro Conference on Real-Time Systems (ECRTS 2017). - : Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik. - 9783959770378
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Konferensbidrag (refereegranskat)abstract
- The Controller Area Network with Flexible Data-Rate (CAN-FD) is a new communication protocol to meet the bandwidth requirements for the constantly growing volume of data exchanged in modern vehicles. The problem of frame packing for CAN-FD, as studied in the literature, assumes a single sub-system where one CAN-FD bus serves as the communication medium among several Electronic Control Units (ECUs). Modern automotive electronic systems, on the other hand, consist of several sub-systems, each facilitating a certain functional domain such as powertrain, chassis and suspension. A substantial fraction of all signals is exchanged across sub-systems. In this work, we study the frame packing problem for CAN-FD with multiple sub-systems, and propose a two-stage optimization framework. In the first stage, we pack the signals into frames with the objective of minimizing the bandwidth utilization. In the second stage, we extend Audsley's algorithm to assign priorities/identifiers to the frames. In case the resulting solution is not schedulable, our framework provides a potential repacking method. We propose two solution approaches: (a) an Integer Linear Programming (ILP) formulation that provides an optimal solution but is computationally expensive for industrial-size problems; and (b) a greedy heuristic that scales well and provides solutions that are comparable to optimal solutions. Experimental results show the efficiency of our optimization framework in achieving feasible solutions with low bandwidth utilization. The results also show a significant improvement over the case when there is no cross-domain consideration (as in prior work).
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| 11. |
- Li, Xiansheng, et al.
(författare)
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A Multifunctional Small-Molecule Hole- Transporting Material Enables Perovskite QLEDs with EQE Exceeding 20%
- 2023
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Ingår i: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 8:3, s. 1445-1454
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Tidskriftsartikel (refereegranskat)abstract
- Hole-transporting materials (HTMs) play critical roles in the device performance and stability of perovskite quantum dot light-emitting diodes (Pe-QLEDs). However, the development of small-molecule HTMs for achieving high-performance Pe-QLEDs has proven to be very challenging because of their low hole mobility and poor solvent resistance. Herein, we tailor-made a multifunc-tional small-molecule HTM, termed X10, with methoxy as the substituents, for application in Pe-QLEDs. X10 features high hole mobility, good film-forming ability, and strong solvent resistance ability as well as defect passivation effect. Subsequently, Pe-QLEDs employing X10 as HTM presented a promising external quantum efficiency (EQE) of 20.18%, which is 7-fold higher than that of the reference HTM-TCTA-based ones (EQE approximate to 2.88%). To the best of our knowledge, this is the first case in which a small-molecule HTM displays a high EQE over 20% in Pe-QLEDs. Our work provides important guidance for the rational design of multifunctional small-molecule HTMs for high-performance Pe-QLEDs.
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| 12. |
- Natarajan, Saranya
(författare)
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Programming Language Primitives and Tools for Integrated Real-Time Systems Development
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The correctness of real-time systems depends on both its logical and temporal correctness. Typically, real-time systems are developed in several steps. First, the application is divided into a number of recurrent tasks and implemented using a programming language. Second, the worst-case execution time (WCET) of each task is estimated for a specific hardware platform. Finally, schedulability analysis is performed to determine if the timing requirements are met on the specified hardware. There are several challenges in each of these complex steps, as well as how to integrate them in a systematic way. Moreover, many small-scale embedded systems are implemented using the C programming language. However, the C programming language has no direct primitives for programming the system’s temporal requirements. Similarly, the uncertainties in the measured WCET values and the release jitter can render the result of the schedulability analysis unreliable. Further, the practical differences in the tools used in each of these steps make the integrated development of real-time systems challenging. In this dissertation, we propose a set of programming primitives and tools for the integrated development of real-time systems. More specifically, we propose a small number of language primitives for programming timing, concurrency, and scheduling requirements of real-time systems. We introduce Timed C, a programming language for real-time systems that extends the C programming language with the proposed language primitives. We propose a seamless and pragmatic end-to-end toolchain that integrates the Timed C programming language, a source-to-source compiler, timing analysis, schedulability analysis, and a novel sensitivity analysis. The new approach to sensitivity analysis determines the worst-case execution time margins for weakly-hard real-time systems. We formalize a subset of the Timed C semantics and use this to design a new temporal property-based testing tool and methodology. Finally, we evaluate the proposed programming language and tools using experiments and case studies.
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| 13. |
- Yuan, Shichen, et al.
(författare)
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Balancing Charge Injection via a Tailor-Made Electron-Transporting Material for High Performance Blue Perovskite QLEDs
- 2023
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Ingår i: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 8:1, s. 818-826
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Tidskriftsartikel (refereegranskat)abstract
- One of the great challenges in perovskite quantum dot light-emitting diodes (Pe-QLEDs) is the unbalanced charge injection that significantly hinders the device performance and stability. Herein, we tailor-made a high mobility electron-transporting material (ETM), named B2, to balance the carrier injection in blue Pe-QLEDs. B2 with a tailored asymmetric anthracenyl structure exhibits a promising electron mobility of 2.7 x 10(-4) cm(2)center dot V-1 center dot s(-1), which is almost 20 times higher than the commonly used ETM-TPBi (1.1 x 10(-5) cm(2)center dot V-1 center dot s(-1)). Subsequently, sky blue (490 nm) Pe-QLED with B2 as the ETM presented a remarkably high external quantum efficiency (EQE) of 13.17% and a low turn-on voltage of 2.2 V, which is much better than that of the TPBi-based device (EQE of 8.31% and Vturn-on of 3.2 V). In addition, B2 also demonstrated a universal application in green and deep blue Pe-QLEDs. This work provides an important guidance to rational design of high electron mobility ETMs for high-performance LEDs.
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| 14. |
- Zeng, Haibo, et al.
(författare)
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Networked Real-Time Embedded Systems
- 2017
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Ingår i: Handbook of Hardware/Software Codesign. - Dordrecht : Springer. - 9789401772662 - 9789401772679 - 9789401772686 ; , s. 753-792
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Bokkapitel (refereegranskat)abstract
- This chapter gives an overview on various real-time communication protocols, from the Controller Area Network (CAN) that was standardized over twenty years ago but is still popular, to the FlexRay protocol that provides strong predictability and fault tolerance, to the more recent Ethernet-based networks. The design of these protocols including their messaging mechanisms was driven by diversified requirements on bandwidth, real-time predictability, reliability, cost, etc. The chapter provides three examples of real-time communication protocols: CAN as an example of event-triggered communication, FlexRay as a heterogeneous protocol supporting both time-triggered and event-triggered communications, and different incarnations of Ethernet that provide desired temporal guarantees.
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| 15. |
- Zhang, Jibin, et al.
(författare)
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Ligand-Induced Cation-p Interactions Enable High-Efficiency, Bright, and Spectrally Stable Rec. 2020 Pure-Red Perovskite Light-Emitting Diodes
- 2023
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095.
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Tidskriftsartikel (refereegranskat)abstract
- Achieving high-performance perovskite light-emitting diodes (PeLEDs) with pure-red electroluminescence for practical applications remains a critical challenge because of the problematic luminescence property and spectral instability of existing emitters. Herein, high-efficiency Rec. 2020 pure-red PeLEDs, simultaneously exhibiting exceptional brightness and spectral stability, based on CsPb(Br/I)(3) perovskite nanocrystals (NCs) capping with aromatic amino acid ligands featuring cation-pi interactions, are reported. It is proven that strong cation-pi interactions between the PbI6-octahedra of perovskite units and the electron-rich indole ring of tryptophan (TRP) molecules not only chemically polish the imperfect surface sites, but also markedly increase the binding affinity of the ligand molecules, leading to high photoluminescence quantum yields and greatly enhanced spectral stability of the CsPb(Br/I)(3) NCs. Moreover, the incorporation of small-size aromatic TRP ligands ensures superior charge-transport properties of the assembled emissive layers. The resultant devices emitting at around 635 nm demonstrate a champion external quantum efficiency of 22.8%, a max luminance of 12 910 cd m(-2), and outstanding spectral stability, representing one of the best-performing Rec. 2020 pure-red PeLEDs achieved so far.
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| 16. |
- Zhang, Lixiu, et al.
(författare)
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Advances in the Application of Perovskite Materials
- 2023
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Ingår i: NANO-MICRO LETTERS. - : SHANGHAI JIAO TONG UNIV PRESS. - 2311-6706. ; 15:1
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Forskningsöversikt (refereegranskat)abstract
- Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices (solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices (artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.
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| 17. |
- Zhao, Qingling, et al.
(författare)
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CAN bus intrusion detection based on auxiliary classifier GAN and out-of-distribution detection
- 2022
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Ingår i: ACM Transactions on Embedded Computing Systems. - : Association for Computing Machinery (ACM). - 1539-9087 .- 1558-3465. ; 21:4
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Tidskriftsartikel (refereegranskat)abstract
- The Controller Area Network (CAN) is a ubiquitous bus protocol present in the Electrical/Electronic (E/E) systems of almost all vehicles. It is vulnerable to a range of attacks once the attacker gains access to the bus through the vehicle's attack surface. We address the problem of Intrusion Detection on the CAN bus and present a series of methods based on two classifiers trained with Auxiliary Classifier Generative Adversarial Network (ACGAN) to detect and assign fine-grained labels to Known Attacks and also detect the Unknown Attack class in a dataset containing a mixture of (Normal + Known Attacks + Unknown Attack) messages. The most effective method is a cascaded two-stage classification architecture, with the multi-class Auxiliary Classifier in the first stage for classification of Normal and Known Attacks, passing Out-of-Distribution (OOD) samples to the binary Real-Fake Classifier in the second stage for detection of the Unknown Attack class. Performance evaluation demonstrates that our method achieves both high classification accuracy and low runtime overhead, making it suitable for deployment in the resource-constrained in-vehicle environment.
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| 18. |
- Zhao, Qingling, et al.
(författare)
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Minimizing Stack Memory for Partitioned Mixed-criticality Scheduling on Multiprocessor Platforms
- 2022
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Ingår i: ACM Transactions on Embedded Computing Systems. - : ACM Digital Library. - 1539-9087 .- 1558-3465. ; 21:2
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Tidskriftsartikel (refereegranskat)abstract
- A Mixed-Criticality System (MCS) features the integration of multiple subsystems that are subject to different levels of safety certification on a shared hardware platform. In cost-sensitive application domains such as automotive E/E systems, it is important to reduce application memory footprint, since such a reduction may enable the adoption of a cheaper microprocessor in the family. Preemption Threshold Scheduling (PTS) is a well-known technique for reducing system stack usage. We consider partitioned multiprocessor scheduling, with Preemption Threshold Adaptive Mixed-Criticality (PT-AMC) as the task scheduling algorithm on each processor and address the optimization problem of finding a feasible task-To-processor mapping with minimum total system stack usage on a resource-constrained multi-processor. We present the Extended Maximal Preemption Threshold Assignment Algorithm (EMPTAA), with dual purposes of improving the taskset's schedulability if it is not already schedulable, and minimizing system stack usage of the schedulable taskset. We present efficient heuristic algorithms for finding sub-optimal yet high-quality solutions, including Maximum Utilization Difference based Partitioning (MUDP) and MUDP with Backtrack Mapping (MUDP-BM), as well as a Branch-And-Bound (BnB) algorithm for finding the optimal solution. Performance evaluation with synthetic task sets demonstrates the effectiveness and efficiency of the proposed algorithms.
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