42 research outputs found

    Formal Analysis of Fairness for Optimistic Multiparty Contract Signing Protocol

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    Optimistic multiparty contract signing (OMPCS) protocols are proposed for exchanging multiparty digital signatures in a contract. Compared with general two-party exchanging protocols, such protocols are more complicated, because the number of protocol messages and states increases considerably when signatories increase. Moreover, fairness property in such protocols requires protection from each signatory rather than from an external hostile agent. It thus presents a challenge for formal verification. In our analysis, we employ and combine the strength of extended modeling language CSP# and linear temporal logic (LTL) to verify the fairness of OMPCS protocols. Furthermore, for solving or mitigating the state space explosion problem, we set a state reduction algorithm which can decrease the redundant states properly and reduce the time and space complexity greatly. Finally, this paper illustrates the feasibility of our approach by analyzing the GM and CKS protocols, and several fairness flaws have been found in certain computation times

    Research on Image Splicing and Fusion Processing Algorithm in Large Visual Field

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    To obtain wide area and a large field of view image, splicing and fusion algorithm is presented. Single image is preprocessed by utilizing rough matching algorithm, which can narrow down the matching range to improve the speed and precision of image stitching and fusion, at the same time, Single image is preprocessed by filter processing algorithm, which will reduce interference noise, improve SNR and enhance the effective character information of image; the best matching position is found by using a combined splicing algorithm, which are ratio template matching algorithm and template matching algorithm, and the images are spliced at the best matching position; we take the neighborhood weighted average fusion algorithm to eliminate the distinct splicing trace. The captured images are processed by using correlation algorithm, a large field of view and high quality image is obtained. The experimental results verify the validity of the algorithm

    EEG Feature Analysis Related to Situation Awareness Assessment and Discrimination

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    In order to discriminate situation awareness (SA) levels on the basis of SA-sensitive electroencephalography (EEG) features, the high-SA (HSA) group and low-SA (LSA) groups, which are representative of two SA levels, were classified according to the situation awareness global assessment technology (SAGAT) scores measured in the multi-attribute task battery (MATB) II tasks. Furthermore, three types of EEG features, namely, absolute power, relative power, and slow-wave/fast-wave (SW/FW), were explored using spectral analysis. In addition, repeated analysis of variance (ANOVA) was conducted in three brain regions (frontal, central, and parietal) × three brain lateralities (left, middle, and right) × two SA groups (LSA and HSA) to explore SA-sensitive EEG features. The statistical results indicate a significant difference between the two SA groups according to SAGAT scores; moreover, no significant difference was found for the absolute power of four waves (delta (δ), theta (θ), alpha (α), and beta (β)). In addition, the LSA group had a significantly lower β relative power than the HSA group in central and partial regions. Lastly, compared with the HSA group, the LSA group had higher θ/β and (θ + α)/(α + β) in all analyzed brain regions, higher α/β in the parietal region, and higher (θ + α)/β in all analyzed regions except for the left and right laterality in the frontal region. The above SA-sensitive EEG features were fed into principal component analysis (PCA) and the Bayes method to discriminate different SA groups, and the accuracies were 83.3% for the original validation and 70.8% for the cross-validation. The results provide a basis for real-time assessment and discrimination of SA by investigating EEG features, thus contributing to monitoring SA decrement that might lead to threats to flight safety

    EEG Feature Analysis Related to Situation Awareness Assessment and Discrimination

    No full text
    In order to discriminate situation awareness (SA) levels on the basis of SA-sensitive electroencephalography (EEG) features, the high-SA (HSA) group and low-SA (LSA) groups, which are representative of two SA levels, were classified according to the situation awareness global assessment technology (SAGAT) scores measured in the multi-attribute task battery (MATB) II tasks. Furthermore, three types of EEG features, namely, absolute power, relative power, and slow-wave/fast-wave (SW/FW), were explored using spectral analysis. In addition, repeated analysis of variance (ANOVA) was conducted in three brain regions (frontal, central, and parietal) × three brain lateralities (left, middle, and right) × two SA groups (LSA and HSA) to explore SA-sensitive EEG features. The statistical results indicate a significant difference between the two SA groups according to SAGAT scores; moreover, no significant difference was found for the absolute power of four waves (delta (δ), theta (θ), alpha (α), and beta (β)). In addition, the LSA group had a significantly lower β relative power than the HSA group in central and partial regions. Lastly, compared with the HSA group, the LSA group had higher θ/β and (θ + α)/(α + β) in all analyzed brain regions, higher α/β in the parietal region, and higher (θ + α)/β in all analyzed regions except for the left and right laterality in the frontal region. The above SA-sensitive EEG features were fed into principal component analysis (PCA) and the Bayes method to discriminate different SA groups, and the accuracies were 83.3% for the original validation and 70.8% for the cross-validation. The results provide a basis for real-time assessment and discrimination of SA by investigating EEG features, thus contributing to monitoring SA decrement that might lead to threats to flight safety

    Stage 1 hypertension defined by the 2017 ACC/AHA blood pressure guideline and cardiometabolic multimorbidity in Chinese adults

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    Abstract The association of blood pressure (BP) classification defined by the 2017 American College of Cardiology/American Heart Association (ACC/AHA) guideline with cardiometabolic multimorbidity (CMM) remains unclear. The present study aimed to investigate this research gap in the Chinese adults. Cross‐sectional data were collected from a population‐based cohort conducted in Southern China. Participants were categorized as having normal BP, elevated BP, stage 1 hypertension, and stage 2 hypertension according to the 2017 ACC/AHA guideline. CMM was defined as having two or more of the following diseases: coronary heart disease, stroke, and diabetes. The relationship between the BP classifications and CMM was examined by multivariate logistic regression. A total of 95 649 participants (mean age: 54.3 ± 10.2 years, 60.7% were women) were enrolled in this study. Multivariable‐adjusted logistic regression models revealed that stage 1 hypertension (odds ratio [OR], 1.35; 95% confidence interval [CI], 1.03–1.78) and stage 2 hypertension (OR, 3.53; 95% CI, 2.82–4.47) were significantly associated with a higher prevalence of CMM compared with normal BP. The association between stage 1 hypertension and CMM were profound in women (OR, 1.76; 95% CI, 1.17–2.67) and in the middle‐aged group (OR, 1.53; 95% CI, 1.02–2.35) compared with men and older individuals, respectively. Our study showed that among Chinese adults, stage 1 hypertension defined by the 2017 ACC/AHA guideline was already associated with higher odds of CMM compared with normal BP, particularly in women and middle‐aged participants. Managing stage 1 hypertension may be an important measure to prevent CMM in Chinese adults

    Outstanding fracture toughness combines gigapascal yield strength in an N-doped heterostructured medium-entropy alloy

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    The superior strength and toughness balance prevails in the face-centered-cubic-structured high/medium-entropy alloys (H/MEAs) of low strength, while a gain in yield strength is normally accompanied by a sacrifice in toughness, leading to the strength and toughness trade-off particularly when yield strength increases to the gigapascal levels. Here, we showed the superior fracture toughness by heterostructuring an N-doped CrCoNi MEA having different levels of yield strength higher than 1 GPa. The fracture toughness was 91 MPa.m(1/2) at yield strength of 1.3 GPa in the heterogeneous lamella structure and 168 MPa.m(1/2) at yield strength of 1.0 GPa in the heterogeneous grain structure. The fracture toughness was attributed to forest hardening plus an extra hetero-deformation induced hardening. The pile-ups of geometrically necessary dislocations were observed to be formed at the domain boundaries to accommodate strain gradient at the plastic zone of the crack tip. The chemical short-range orders were found for the enhanced strain hardening near the crack tip by the interaction with dislocations. Moreover, a new parameter was proposed to characterize the work hardening capacity at the crack tip by the integral of hardness increment in the plastic zone which shows a linear relation-ship with the J-integral value during the crack initiation
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