4,218 publications from this institution
We present a built-in self-test (BIST) approach for full-scan designs that extracts the most frequently occurring sequences from deterministic test patterns. The extracted sequences are stored on-chip, and are used during test application. Three sets of test patterns are applied to the circuit under test during a BIST test session; these include pseudorandom patterns, semirandom patterns, and deterministic patterns. The semirandom patterns are generated based on the stored sequences and they are more likely to detect hard-to-detect faults than pseudorandom patterns. The deterministic patterns are encoded using either the stored sequences or the LFSR reseeding technique to reduce test data volume. We use the cluster analysis technique for sequence extraction to reduce the amount of data to be stored. Experimental results for the ISCAS-89 benchmark circuits show that the proposed approach often requires less on-chip storage and test data volume than other recent BIST methods.
Abstract Background Since late 2021, the highly transmissible SARS-CoV-2 Omicron variant has driven a new surge of infections across the world. We used a case-ascertained study to determine the features of household transmission of SARS-CoV-2 Omicron variant in Shanghai, China. Methods We collected detailed information on 323 pediatric cases and their 951 household members in April 2022 during the Omicron outbreak. All household members received consecutively intensive RT-PCR testing for SARS-CoV-2 and routine symptom monitoring within 14 days after exposure to a confirmed case. We described the characteristics of study participants and estimated the transmission parameters. Both secondary infection attack rates (SAR I ) and secondary clinical attack rates (SAR C ) among adult household contacts were computed, through which the transmission heterogeneities in infectivity and susceptibility were characterized and the vaccine effectiveness were estimated. Results We estimated the mean incubation period of SARS-CoV-2 Omicron variant to be 4.6 (median: 4.4, IQR: 3.1-6.0) days and the mean serial interval to be 3.9 (median:4.0, IQR: 1.4-6.5) days. The overall SAR I and SAR C among adult household contacts were 77.11% (95% confidence interval [CI]: 73.58%-80.63%) and 67.03% (63.09%-70.98%). We found higher household susceptibility in females, while infectivity was not significantly different in primary cases by age, sex, vaccination status and clinical severity. The estimated VEs of full vaccination was 14.8% (95% CI: 5.8%-22.9%) against Omicron infection and 21.5% (95% CI: 10.4%-31.2%) against symptomatic disease. The booster vaccination was 18.9% (95% CI: 9.0%-27.7%) and 24.3% (95% CI: 12.3%-34.7%) effective against infection and symptomatic disease, respectively. Conclusions We found high household transmission during the Omicron wave in Shanghai due to asymptomatic and pre-symptomatic transmission in the context of city-wide lockdown, indicating the importance of early detection and timely isolation of SARS-CoV-2 infections and quarantine of close contacts. Marginal effectiveness of inactivated vaccines against Omicron infection poses great challenge for prevention and control of the SARS-CoV-2 Omicron variant.
Self-powered system is a system that can sustainably operate without an external power supply for sensing, detection, data processing and data transmission. Nanogenerators were first developed for self-powered systems based on piezoelectric effect and triboelectrification effect for converting tiny mechanical energy into electricity, which have applications in internet of things, environmental/infrastructural monitoring, medical science and security. In this paper, we present the fundamental theory of the nanogenerators starting from the Maxwell equations. In the Maxwell's displacement current, the first term ε0∂E∂t gives the birth of electromagnetic wave, which is the foundation of wireless communication, radar and later the information technology. Our study indicates that the second term ∂P∂t in the Maxwell's displacement current is directly related to the output electric current of the nanogenerator, meaning that our nanogenerators are the applications of Maxwell's displacement current in energy and sensors. By contrast, electromagnetic generators are built based on Lorentz force driven flow of free electrons in a conductor. This study presents the similarity and differences between pieozoelectric nanogenerator and triboelectric nanogenerator, as well as the classical electromagnetic generator, so that the impact and uniqueness of the nanogenerators can be clearly understood. We also present the three major applications of nanogenerators as micro/nano-power source, self-powered sensors and blue energy.
Abstract We present a new approach for fabricating flexible fiber nanogenerators (FNGs) that can be used for smart shirts, flexible electronics, and medical applications. These FNGs are based on carbon fibers that are covered cylindrically by textured zinc oxide (ZnO) thin films. Once subjected to uni‐compression by applying a pressure, the cylindrical ZnO thin film is under a compressive strain, resulting in a macroscopic piezopotential across its inner and exterior surfaces owing to the textured structure of the film, which is the driving force for generating an electric current in the external load. Using such a structure, an output peak voltage of 3.2 V and average current density of 0.15 μA cm −2 are demonstrated. The FNGs rely on air pressure, so that it can work in a non‐contact mode in cases of rotating tires, flowing air/liquid, and even in blood vessels. Pressure‐driven FNGs added to a syringe show potential to harvest energy in blood vessels, gas pipes, and oil pipes, as long as there is a fluctuation in pressure (or turbulence). Heart‐pulse driven FNGs can serve as ultrasensitive sensors for monitoring the behavior of the human heart, which may possibly be applied to medical diagnostics as sensors and measurement tools.
In this paper, the radial basis vector (RBV) is proposed to describe the descriptor set of an image. And the shared nearest neighbor clustering kernel (SNNCK) technique is proposed to match RBV pairs. SNNCK is based on the charge attractive model, which will make the unequal-dimensional data sets clustering naturally. Thus, this novel algorithm is able to match the unequal-dimensional data sets when the number of descriptors of two images are unequal. It also can automatically extract the repetition pattern of the reference date set, which is helpful to avoid the wrong matching. Experimental results are also provided, and these results demonstrate superior performances of SNNCK algorithm by using the feature point sets with strong disturbs.