Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enh...Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enhance the performance of guided wave damage detection in noisy environments is crucial.This paper introduces a local temporal principal component analysis(PCA)reconstruction approach for denoising guided waves prior to implementing unsupervised damage detection,achieved through novel autoencoder-based reconstruction.Experimental results demonstrate that the proposed denoising method significantly enhances damage detection performance when guided waves are contaminated by noise,with SNR values ranging from 10 to-5 dB.Following the implementation of the proposed denoising approach,the AUC score can elevate from 0.65 to 0.96 when dealing with guided waves corrputed by noise at a level of-5 dB.Additionally,the paper provides guidance on selecting the appropriate number of components used in the denoising PCA reconstruction,aiding in the optimization of the damage detection in noisy conditions.展开更多
Cardiovascular disease persists as the primary cause of human mortality,significantly impacting healthy life expectancy.The routine electrocardiogram(ECG)stands out as a pivotal noninvasive diagnostic tool for identif...Cardiovascular disease persists as the primary cause of human mortality,significantly impacting healthy life expectancy.The routine electrocardiogram(ECG)stands out as a pivotal noninvasive diagnostic tool for identifying arrhythmias.The evolving landscape of fabric electrodes,specifically designed for the prolonged monitoring of human ECG signals,is the focus of this research.Adhering to the preferred reporting items for systematic reviews and meta-analyses(PRISMA)statement and assimilating data from 81 pertinent studies sourced from reputable databases,the research conducts a comprehensive systematic review and meta-analysis on the materials,fabric structures and preparation methods of fabric electrodes in the existing literature.It provides a nuanced assessment of the advantages and disadvantages of diverse textile materials and structures,elucidating their impacts on the stability of biomonitoring signals.Furthermore,the study outlines current developmental constraints and future trajectories for fabric electrodes.These insights could serve as essential guidance for ECG monitoring system designers,aiding them in the selection of materials that optimize the measurement of biopotential signals.展开更多
As semiconductor manufacturing migrates to more advanced technology nodes, accelerated aging effect for nanoscale devices poses as a key challenge for designers to find countermeasures that effectively mitigate the de...As semiconductor manufacturing migrates to more advanced technology nodes, accelerated aging effect for nanoscale devices poses as a key challenge for designers to find countermeasures that effectively mitigate the degradation and prolong system's lifetime. Negative Bias Temperature Instability (NBTI) is emerging as one of the major reliability concerns. Two software tools for NBTI analyzing are proposed in this paper, one for transistor-level, and the other for gate-level. The transistor-level can be used to estimate the delay degradation due to NBTI effect very accurately, while the gate-level can be used for repeat analysis in circuit optimization because of its fast computing speed.展开更多
Most currently existing investigations on the observability of passive guidance systems can only provide a qualitative result. In this paper, a quantitative method, which utilizes Cramér-Rao lower bound in the es...Most currently existing investigations on the observability of passive guidance systems can only provide a qualitative result. In this paper, a quantitative method, which utilizes Cramér-Rao lower bound in the estimability analysis of closed-loop guidance systems with bearings-only measurements, is proposed. The new method provides an intuitive result for observability of the guidance system through graphical analysis. As a demonstration, a numerical example is presented, in which the degrees of observability of the guidance systems under two commonly used guidance laws are compared by using the new approach.展开更多
Today, the GNSS （global navigation satellite system） is used for more complicate and accurate applications such as monitoring or stake out works. The truth lies in the fact that in the most of the times not enough a...Today, the GNSS （global navigation satellite system） is used for more complicate and accurate applications such as monitoring or stake out works. The truth lies in the fact that in the most of the times not enough attention is paid to the antenna＇s setup. Usually, gross errors are found in the antenna＇s centering, leveling and in the measurement of its height, which are significant. In this paper, a thoroughly analysis of the above mentioned errors is carried out. The influence of these errors in the calculation of the X, Y, Z Cartesian geocentric coordinates and the ~, 2, h ellipsoid geodetic coordinates of a point P on the earth＇s surface, is analyzed and is presented in several diagrams. Also a new convenient method for the accurate measurement of the antenna＇s height is presented and it is strongly proposed. The conclusions outline the magnitude of these errors and prove the significance of the antenna＇s proper setup at the accurate GNSS applications.展开更多
基金National Science Foundation of Zhejiang under Contract(LY23E010001)。
文摘Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enhance the performance of guided wave damage detection in noisy environments is crucial.This paper introduces a local temporal principal component analysis(PCA)reconstruction approach for denoising guided waves prior to implementing unsupervised damage detection,achieved through novel autoencoder-based reconstruction.Experimental results demonstrate that the proposed denoising method significantly enhances damage detection performance when guided waves are contaminated by noise,with SNR values ranging from 10 to-5 dB.Following the implementation of the proposed denoising approach,the AUC score can elevate from 0.65 to 0.96 when dealing with guided waves corrputed by noise at a level of-5 dB.Additionally,the paper provides guidance on selecting the appropriate number of components used in the denoising PCA reconstruction,aiding in the optimization of the damage detection in noisy conditions.
文摘Cardiovascular disease persists as the primary cause of human mortality,significantly impacting healthy life expectancy.The routine electrocardiogram(ECG)stands out as a pivotal noninvasive diagnostic tool for identifying arrhythmias.The evolving landscape of fabric electrodes,specifically designed for the prolonged monitoring of human ECG signals,is the focus of this research.Adhering to the preferred reporting items for systematic reviews and meta-analyses(PRISMA)statement and assimilating data from 81 pertinent studies sourced from reputable databases,the research conducts a comprehensive systematic review and meta-analysis on the materials,fabric structures and preparation methods of fabric electrodes in the existing literature.It provides a nuanced assessment of the advantages and disadvantages of diverse textile materials and structures,elucidating their impacts on the stability of biomonitoring signals.Furthermore,the study outlines current developmental constraints and future trajectories for fabric electrodes.These insights could serve as essential guidance for ECG monitoring system designers,aiding them in the selection of materials that optimize the measurement of biopotential signals.
基金Supported by the National Key Technological Program of China (No.2008ZX01035-001)the National Natural Sci-ence Foundation of China (No.60870001)TNList Cross-discipline Fundation
文摘As semiconductor manufacturing migrates to more advanced technology nodes, accelerated aging effect for nanoscale devices poses as a key challenge for designers to find countermeasures that effectively mitigate the degradation and prolong system's lifetime. Negative Bias Temperature Instability (NBTI) is emerging as one of the major reliability concerns. Two software tools for NBTI analyzing are proposed in this paper, one for transistor-level, and the other for gate-level. The transistor-level can be used to estimate the delay degradation due to NBTI effect very accurately, while the gate-level can be used for repeat analysis in circuit optimization because of its fast computing speed.
基金the National Natural Science Foundation of China (Grant No. 60104003 and 60374024).
文摘Most currently existing investigations on the observability of passive guidance systems can only provide a qualitative result. In this paper, a quantitative method, which utilizes Cramér-Rao lower bound in the estimability analysis of closed-loop guidance systems with bearings-only measurements, is proposed. The new method provides an intuitive result for observability of the guidance system through graphical analysis. As a demonstration, a numerical example is presented, in which the degrees of observability of the guidance systems under two commonly used guidance laws are compared by using the new approach.
文摘Today, the GNSS （global navigation satellite system） is used for more complicate and accurate applications such as monitoring or stake out works. The truth lies in the fact that in the most of the times not enough attention is paid to the antenna＇s setup. Usually, gross errors are found in the antenna＇s centering, leveling and in the measurement of its height, which are significant. In this paper, a thoroughly analysis of the above mentioned errors is carried out. The influence of these errors in the calculation of the X, Y, Z Cartesian geocentric coordinates and the ~, 2, h ellipsoid geodetic coordinates of a point P on the earth＇s surface, is analyzed and is presented in several diagrams. Also a new convenient method for the accurate measurement of the antenna＇s height is presented and it is strongly proposed. The conclusions outline the magnitude of these errors and prove the significance of the antenna＇s proper setup at the accurate GNSS applications.
