To quantitatively predict software security, a component security model is proposed based on Stochastic Petri Nets (SPNs). An isomorphic Markov Chain (MC) is obtained from the component SPN model. A quantitative secur...
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We present a formal specification to engineer situated multi-agent Systems (situated MAS), which has revealed the need for specifying and reasoning of its global property. This paper shows how MAS is specified with mo...
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We present a formal specification to engineer situated multi-agent Systems (situated MAS), which has revealed the need for specifying and reasoning of its global property. This paper shows how MAS is specified with modified Object-Z notation with trace semantic of action system, and how to reason about safety and liveness property in this specification. Independent and joint MAS examples are are used to illustrate specifying and reasoning in specification for situated MAS.
Nowadays a large number of applications requires continuous and timely processing of information as it flows from the periphery to the center of the system. Among numerous tools that support these scenarios, the Esper...
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Data cleaning is an important problem and data quality rules are the most promising way to address it. Previous researches have focused on constraints, such as functional dependencies (FDs), conditional functional dep...
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This paper introduces a test method based on chain unique input/output(CUIO) sequence in finite state machine(FSM) conformance testing. For FSMs with UIO for each state, the test sequence based on CUIO can identify al...
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This paper introduces a test method based on chain unique input/output(CUIO) sequence in finite state machine(FSM) conformance testing. For FSMs with UIO for each state, the test sequence based on CUIO can identify all the states and verify all the transitions. For FSMs without UIO for some states, the test sequence based on CUIO can identify as many states and verify as many transitions as possible. Meanwhile, W method is introduced to deal with the unidentified states and the unverified transitions. For FSMs without UIO for each state, the method completely degenerates to W method. It is proved by experiment that the average and maximum reduction rate are 45.5% and 63.2% comparing with UIO ***, the method is always feasible even when UIO method fails.
TCPNIA (Timed Colored Petri Nets with Inhibitor Arcs, TCPNIA) is a model for specifying real-time embedded systems. It integrates features of colored Petri nets, timed Petri nets and inhibitor arcs. The methods for mo...
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As the turnout is a critical part of railway tracks, its surface defects are directly related to the operation safety. The defects detection of turnout is an effect way to ensure the safety and comfort of urban transi...
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ISBN:
(纸本)9781467374439
As the turnout is a critical part of railway tracks, its surface defects are directly related to the operation safety. The defects detection of turnout is an effect way to ensure the safety and comfort of urban transit railway. In this paper, the feature extraction of the turnout defects is investigated based on the bogie acceleration measurements. The normal turnout model and faulty turnout model based on SIMPACK are established first, from which the vehicle vibration acceleration is obtained. Then, the acceleration signal is analyzed in time- frequency domain. The results show that the power spectral density(PSD) and all the frequency-domain features are useful for detecting the poor fit defect of the switch point. And the peak and PSD features can be used to detect the curve opposite super-elevation. The proposed method provides alternative for the detection of turnout defects by using in-service vehicle.
The squat is a type of rolling contact fatigue(RCF) damage,the existence of squats directly impacts the operating condition of urban rail *** current detection methods of the rail squats damage are mainly based on tra...
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ISBN:
(纸本)9781467397155
The squat is a type of rolling contact fatigue(RCF) damage,the existence of squats directly impacts the operating condition of urban rail *** current detection methods of the rail squats damage are mainly based on track inspection car and rail flaw *** has some disadvantages,for example,long detection cycle,no real-time detecting and narrow scope,time consuming and *** this paper,a new detection method of squats which based on the in-service vehicles is *** bogie acceleration signal is used to detect the squats on the *** validate the possibility of the proposed *** the help of SIMPACK software,an in-service vehicle-track dynamic model and models of typical squats are built to generate the simulated bogie acceleration signals when the train wheels rolls over the *** simulation signals from the normal rail and the rail with squats are studied by HHT,it is found that0~50Hz and 300 Hz are the feature frequency caused by the squats damages.A unique W-shaped natural vibration mode is decomposed from the acceleration signals which is the feature vibration mode of the squat ***,the above detection method is applied to the field test data of shanghai metro line *** feasibility and reliability of the proposed method are *** proposed method provides an alternative for real application.
Face anti-spoofing (FAS) based on domain generalization (DG) has been recently studied to improve the generalization on unseen scenarios. Previous methods typically rely on domain labels to align the distribution of e...
Face anti-spoofing (FAS) based on domain generalization (DG) has been recently studied to improve the generalization on unseen scenarios. Previous methods typically rely on domain labels to align the distribution of each domain for learning domain-invariant representations. However, artificial domain labels are coarse-grained and subjective, which cannot reflect real domain distributions accurately. Besides, such domain-aware methods focus on domain-level alignment, which is not fine-grained enough to ensure that learned representations are insensitive to domain styles. To address these issues, we propose a novel perspective for DG FAS that aligns features on the instance level without the need for domain labels. Specifically, Instance-Aware Domain Generalization framework is proposed to learn the generalizable feature by weakening the features' sensitivity to instance-specific styles. Concretely, we propose Asymmetric Instance Adaptive Whitening to adaptively eliminate the style-sensitive feature correlation, boosting the generalization. Moreover, Dynamic Kernel Generator and Categorical Style Assembly are proposed to first extract the instance-specific features and then generate the style-diversified features with large style shifts, respectively, further facilitating the learning of style-insensitive features. Extensive experiments and analysis demonstrate the superiority of our method over state-of-the-art competitors. Code will be publicly available at this link.
The railway track squat is one of the most dangerous track defects, it causes large dynamic contact force at the wheel-rail interface, leading to fast deterioration of the track, bring significant harm to the safety o...
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ISBN:
(纸本)9781467374439
The railway track squat is one of the most dangerous track defects, it causes large dynamic contact force at the wheel-rail interface, leading to fast deterioration of the track, bring significant harm to the safety of the passengers. Early detection of such defects is very important for timely maintenance. In this paper, a squats detection method based on bogie acceleration(BA) measurement is presented. A simulation model with acceleration sensors is set up in the SIMPACK simulation environment. Time-frequency analysis and wavelet packet decomposition are applied to analyze these BA data obtained from the simulation model. The effectiveness of the above approach is demonstrated by simulation results.
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