132 research outputs found
A One-Class Classification Method for Human Gait Authentication Using Micro-Doppler Signatures
No full textIn this letter, a radar-based gait authentication method is proposed. We focus on the overfitting problem on the target category caused by limited training data in authentication models and propose a one-class classification model to alleviate this problem. The effectiveness of such model is verified by establishing a radar-based gait dataset, which is composed of gait micro-Doppler spectrograms derived from nine human subjects. The experimental results demonstrate that, under the condition of limited training data, the performances of an authentication model degrade because misclassification of the non-target samples easily occurs. The proposed method effectively avoids this risk, performing the other existing authentication and one-class classification methods on the metric Equal Error Rate.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Microwave Sensing, Signals & System
Physics and applications of resonant tunneling devices
No full textThis thesis addresses several important issues of the physics and applications of double barrier resonant tunneling devices on which the author worked during his graduate study at Caltech:
(1) Epitaxial growth of AlAs/GaAs double barrier resonant tunneling structure on both GaAs and Si substrate (Chapter 2).
(2) Investigation of terahertz modulation of resonant tunneling effect
(Chapter 3).
(3) Study of the imaginary potential in double barrier resonant tunneling (Chapter 4).
(4) Development of the first series of optical resonant tunneling devices and parallel resonant tunneling (Chapter 5).
The history of the development of double barrier resonant tunneling and the basic theory are also discussed (Chapter 1)
The effect of sulfate-rich sewage sludge ash on the volume deformation and micorstructure of cement paste
No full textSewage sludge ash (SSA) is the combustion residue of the sewage sludge obtained from wastewater treatment plants. In China, SSA normally contains high content of SO3, which may cause detrimental effect on the volume stability of cement-based materials. This study investigated the effect of sulfate-rich SSA (SR-SSA) on the volume deformation and the microstructure of cement paste. The autogenous shrinkage and drying shrinkage of cement pastes incorporating SR-SSA were tested. The microstructure of cement pastes incorporating SR-SSA was studied with mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). The results show that the addition of SR-SSA reduced the autogenous shrinkage of cement paste, but increased the drying shrinkage of cement paste. Hence the addition of SSA may cause more serious cracking problem of cement-based materials under drying conditions, but could inhibit the cracking under sealed condition. The SEM and MIP investigations showed that, when SR-SSA was presented, more ettringite was generated in the cement paste and the porosity of the cement paste became higher
Population structure and regeneration constraints of Magnolia zenii (Magnoliaceae) in Baohua Mountain, Jiangsu, China: Insights for conservation strategies
No full textMagnolia zenii Cheng, an endemic and critically endangered species, is restricted to Baohua Mountain, Jiangsu Province, China. Despite the implementation of in situ conservation measures implemented after the establishment of Baohua Mountain Nature Reserve in 1984, the species continues to face significant regeneration challenges.This study evaluates the population structure and regeneration dynamics of M. zenii using data from field surveys conducted in 2001 and 2024. Our findings indicate a substantial increase in the total population size from 34 to 115 individuals and a broadening of the size-class distribution. However, persistent gaps in recruitment, particularly the absence of individuals in the smallest diameter class (< 5 cm), highlight critical reproductive and establishment constraints. Factors limiting regeneration include poor seedling establishment due to reproductive inefficiencies, intense competition from Phoebe sheareri and Phyllostachys edulis and anthropogenic impacts associated with tourism management. We propose a multi-faceted conservation strategy emphasising enhanced reproductive management, mitigation of competitive pressure and science-based tourism control to promote sustainable population recovery. This study provides a comprehensive framework for addressing regeneration constraints and providing information for long-term conservation policies for M. zenii and other endangered species with similar ecological challenges
High frequency model and parameter sensitivity analysis of EMI filter's characteristic in switched mode power supply
No full text
Synthesis and luminescence properties of Li+, Bi3+ ions co-doped CaSiO3:Eu3+ red emitting phosphors
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