Training strategy for a lightweight countermeasure model for automatic speaker verification

The countermeasure (CM) model is developed to protect Automatic Speaker Verification (ASV) systems from spoof attacks and prevent resulting personal information leakage. Based on practicality and security considerations, the CM model is usually deployed on edge devices, which have more limited computing resources and storage space than cloud-based systems. This work proposes training strategies for a lightweight CM model for ASV, using generalized end-to-end (GE2E) pre-training and adversarial fine-tuning to improve performance, and applying knowledge distillation (KD) to reduce the size of the CM model. In the evaluation phase of the ASVspoof 2021 Logical Access task, the lightweight ResNetSE model reaches min t-DCF 0.2695 and EER 3.54%. Compared to the teacher model, the lightweight student model only uses 22.5% of parameters and 21.1% of multiply and accumulate operands of the teacher model.Comment: ASVspoof202

Direct imaging of valence orbitals using hard x-ray photoelectron spectroscopy

It was hypothesized already more than 40 years ago that photoelectron spectroscopy should in principle be able to image atomic orbitals. If this can be made to work for orbitals in crystalline solids, one would have literally a different view on the electronic structure of a wide range of quantum materials. Here, we demonstrate how hard x-ray photoelectron spectroscopy can make direct images of the orbitals making up the band structure of our model system, ReO3. The images are energy specific and enable us to unveil the role of each of those orbitals for the chemical bonding and the Fermi surface topology. The orbital image information is complementary to that from angle-resolved photoemission and thus completes the determination of the electronic structure of materials.It was hypothesized already more than 40 years ago that photoelectron spectroscopy should in principle be able to image atomic orbitals. If this can be made to work for orbitals in crystalline solids, one would have literally a different view on the electronic structure of a wide range of quantum materials. Here, we demonstrate how hard x-ray photoelectron spectroscopy can make direct images of the orbitals making up the band structure of our model system, ReO3. The images are energy specific and enable us to unveil the role of each of those orbitals for the chemical bonding and the Fermi surface topology. The orbital image information is complementary to that from angle-resolved photoemission and thus completes the determination of the electronic structure of materials

An Improved Down-Scale Evaluation System for Capacitors Utilized in High-Power Three-Phase Inverters under Balanced and Unbalanced Load Conditions

The DC-link capacitors in an electronic power system are the main constraint of the power density and lifespan of the power converters. Evaluating the load life of capacitors working in severely adverse circumstances plays an important role in the design stages of the next-generation power converters. In this article, an improved evaluation system for the capacitors utilized in high-power three-phase voltage source inverters is proposed. The purpose of this article is to reproduce the same encountered stresses when a DC-link capacitor is used in a high-power inverter with pulse-width modulation. Hence, an improved down-scale evaluation system for the DC-link capacitors used in high-power three-phase inverter systems under balanced and unbalanced load conditions is proposed. Moreover, AC and DC analyses in the proposed evaluation system are conducted. The equivalent circuit and transfer functions are derived to verify the proposed evaluation system. Finally, a prototype system is constructed to facilitate the theoretical results as the verification

An Improved Down-Scale Evaluation System for Capacitors Utilized in High-Power Three-Phase Inverters under Balanced and Unbalanced Load Conditions

The DC-link capacitors in an electronic power system are the main constraint of the power density and lifespan of the power converters. Evaluating the load life of capacitors working in severely adverse circumstances plays an important role in the design stages of the next-generation power converters. In this article, an improved evaluation system for the capacitors utilized in high-power three-phase voltage source inverters is proposed. The purpose of this article is to reproduce the same encountered stresses when a DC-link capacitor is used in a high-power inverter with pulse-width modulation. Hence, an improved down-scale evaluation system for the DC-link capacitors used in high-power three-phase inverter systems under balanced and unbalanced load conditions is proposed. Moreover, AC and DC analyses in the proposed evaluation system are conducted. The equivalent circuit and transfer functions are derived to verify the proposed evaluation system. Finally, a prototype system is constructed to facilitate the theoretical results as the verification

Light- and Redox-Responsive Block Copolymers of mPEG-SS-ONBMA as a Smart Drug Delivery Carrier for Cancer Therapy

The development of stimuli-responsive polymeric micelles for targeted drug delivery has attracted much research interest in improving therapeutic outcomes. This study designs copolymers responsive to ultraviolet (UV) light and glutathione (GSH). A disulfide linkage is positioned between a hydrophilic poly(ethylene glycol) monomethyl ether (mPEG) and a hydrophobic o-nitrobenzyl methacrylate (ONBMA) to yield amphiphilic copolymers termed mPEG-SS-pONBMA. Three copolymers with different ONBMA lengths are synthesized and formulated into micelles. An increase in particle size and a decrease in critical micelle concentration go together with increasing ONBMA lengths. The ONB cleavage from mPEG-SS-pONBMA-formed micelles results in the transformation of hydrophobic cores into hydrophilic ones, accelerating drug release from the micelles. Obvious changes in morphology and molecular weight of micelles upon combinational treatments account for the dual-stimuli responsive property. Enhancement of a cell-killing effect is clearly observed in doxorubicin (DOX)-loaded micelles containing disulfide bonds compared with those containing dicarbon bonds upon UV light irradiation. Collectedly, the dual-stimuli-responsive mPEG-SS-pONBMA micelle is a better drug delivery carrier than the single-stimuli-responsive mPEG-CC-pONBMA micelle. After HT1080 cells were treated with the DOX-loaded micelles, the high expression levels of RIP-1 and MLKL indicate that the mechanism involved in cell death is mainly via the DOX-induced necroptosis pathway

Optical Interference-Free Surface-Enhanced Raman Scattering CO-Nanotags for Logical Multiplex Detection of Vascular Disease-Related Biomarkers

Matrix metalloproteinases (MMPs), specifically MMP-2, MMP-7, and MMP-9, have been discovered to be linked to many forms of vascular diseases such as stroke, and their detection is crucial to facilitate clinical diagnosis. In this work, we prepared a class of optical interference-free SERS nanotags (CO-nanotags) that can be used for the purpose of multiplex sensing of different MMPs. Multiplex detection with the absence of cross-talk was achieved by using CO-nanotags with individual tunable intrinsic Raman shifts of CO in the 1800–2200 cm^–1 region determined by the metal core and ligands of the metal carbonyl complex. Boolean logic was used as well to simultaneously probe for two proteolytic inputs. Such nanotags offer the advantages of convenient detection of target nanotags and high sensitivity as validated in the ischemia rat model

Three-dimensional metamaterials: from split ring resonator to toroidal metamolecule

Split ring resonator (SRR) has attracted wide attentions since the discovery of negative refraction in 2002. Here, we designed and fabricated vertical SRR (VSRR) arrays and toroidal metamolecule by using double exposure e-beam lithography with precise alignment technique, and their resonance behaviors are subsequently studied in optical region. The fundamental resonance properties of VSRR are studied as well as the plasmon coupling in a VSRR dimer structure by changing the gap distance between SRRs. In addition, we proposed a three-dimensional toroidal structure composed a VSRR with a dumbbell structure that supported a toroidal resonance under normal incidence with broadband working frequency. Such toroidal metamaterial confines effectively the electric as well as magnetic energy paving a way for promising applications in the field of plasmonics, such as integrated 3D plasmonic metamaterials, plasmonic biosensor and lasing spaser

Plasmon coupling in vertical split-ring resonator metamolecules

The past decade has seen a number of interesting designs proposed and implemented to generate artificial magnetism at optical frequencies using plasmonic metamaterials, but owing to the planar configurations of typically fabricated metamolecules that make up the metamaterials, the magnetic response is mainly driven by the electric field of the incident electromagnetic wave. We recently fabricated vertical split-ring resonators (VSRRs) which behave as magnetic metamolecules sensitive to both incident electric and magnetic fields with stronger induced magnetic dipole moment upon excitation in comparison to planar SRRs. The fabrication technique enabled us to study the plasmon coupling between VSRRs that stand up side by side where the coupling strength can be precisely controlled by varying the gap in between. The resulting wide tuning range of these resonance modes offers the possibility of developing frequency selective functional devices such as sensors and filters based on plasmon coupling with high sensitivity.Published versio

Fabrication and measurement of vertical split-ring resonators for light manipulation and metasurface

In the past decade, a number of interesting designs have been proposed to generate artificial magnetism at optical frequencies using plasmonic metamaterials, but owing to the planar configurations of typically fabricated metamaterials, the magnetic response is mainly driven by the incident electric field. Here, we fabricated vertical split-ring resonators (VSRRs) which behave as magnetic metamolecules sensitive to both the incident electric and magnetic fields upon excitation with the stronger induced magnetic energy in comparison to that of planar SRRs. Indeed, the magnetic resonance plays a key factor in plasmon coupling in VSRRs that is totally different from common electric-based metamaterials. A couple of potential applications such as VSRR-based highly sensitive refractive-index sensor and metasurface for light manipulation in optical communication frequency will also be presented. Because the plasmon properties of VSRR are changed via the upright configuration rather than the one parallel to the substrate, it can be used for high area density integration of metal nanostructures and opto-electronic devices