scholarly journals Temporal loss boundary engineered photonic cavity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Longqing Cong ◽  
Jiaguang Han ◽  
Weili Zhang ◽  
Ranjan Singh
Keyword(s):  
Underlying Mechanism ◽  
Gain Medium ◽  
The Other ◽  
Squeezed States ◽  
Low Loss ◽  
Transient Loss ◽  
Dipole Oscillator ◽  
Braking Process ◽  
Coupled Cavity ◽  
Probe Photon

AbstractLosses are ubiquitous and unavoidable in nature inhibiting the performance of most optical processes. Manipulating losses to adjust the dissipation of photons is analogous to braking a running car that is as important as populating photons via a gain medium. Here, we introduce the transient loss boundary into a photon populated cavity that functions as a ‘photon brake’ and probe photon dynamics by engineering the ‘brake timing’ and ‘brake strength’. Coupled cavity photons can be distinguished by stripping one photonic mode through controlling the loss boundary, which enables the transition from a coupled to an uncoupled state. We interpret the transient boundary as a perturbation by considering both real and imaginary parts of permittivity, and the dynamic process is modeled with a temporal two-dipole oscillator: one with the natural resonant polarization and the other with a frequency-shift polarization. The model unravels the underlying mechanism of concomitant coherent spectral oscillations and generation of tone-tuning cavity photons in the braking process. By synthesizing the temporal loss boundary into a photon populated cavity, a plethora of interesting phenomena and applications are envisioned such as the observation of quantum squeezed states, low-loss nonreciprocal waveguides and ultrafast beam scanning devices.

Broadband six-way out-of-phase SIW power divider

2015 ◽  
Vol 8 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Kaijun Song ◽  
Abdullahi Nura Ahmed ◽  
Bingkun Hu ◽  
Yu Zhu ◽  
Fulong Chen ◽  
...  
Keyword(s):  
Reasonable Agreement ◽  
Impedance Matching ◽  
The Other ◽  
Input Port ◽  
Power Divider ◽  
Substrate Integrated Waveguide ◽  
Low Loss ◽  
Size And Shape ◽  
Outer Conductor ◽  
Matching Transformer

A broadband six-way out-of-phase substrate-integrated waveguide (SIW) power divider was designed, analyzed, and fabricated for low loss and out of phase dividing applications. The SIW technology was used to realize the power divider; where it consists of a central dual-disc probe connected with coaxial outer-conductor impedance matching transformer and six SIW-to-microstrip transitions as output probes. Three of the SIW-to-microstrip transitions are located at the top plane, whereas the other three are at the bottom plane of the power divider to achieve the out-of-phase dividing functioning. These transitions are all the same in size and shape for symmetry reason. Good transmissions from coaxial input port to six-way SIW power divider were also achieved. There is a reasonable agreement between measured and simulated results.

scholarly journals Design of Tunable Equalizers Using Multilayered Half Mode Substrate Integrated Waveguide Structures Added Absorbing Pillars

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Shuxing Wang ◽  
Yongfei Wang ◽  
Dewei Zhang ◽  
Yi Zhang ◽  
Dongfang Zhou
Keyword(s):  
Multilayer Structure ◽  
Design Method ◽  
The Other ◽  
Mode Analysis ◽  
Substrate Integrated Waveguide ◽  
Low Loss ◽  
Resonant Cavities ◽  
Bottom Substrate ◽  
Compact Size ◽  
First Time

An equalizer based on multilayered half mode substrate integrated waveguide (HMSIW) structures with highQ-factor, low loss, and compact size is proposed for the first time. Resonant cavities distributing in the upper substrate and the bottom substrate, with the middle substrate layer which works as the transmission line together, constitute a multilayer structure. The design method and theoretical analysis are summarized first. The mode analysis, simulated results, and measured results are all provided. The measured results show a good performance and are in agreement with the simulated results, and the maximum attenuation slope reaches −16 dB over 12.5 GHz~14.5 GHz. With the use of absorbing pillars, the attenuation andQvalue can be tuned more easily than the other planar equalizers. Compared with the SIW equalizer, the size of this structure reduces by 50%. Furthermore, this structure is suitable for the miniaturization development of equalizers.

The Role of Niobium in (Ca, Si, Ce, Nb)-Doped TiO2 Varistors

2007 ◽  
Vol 280-283 ◽  
pp. 297-300 ◽  
Author(s):  
Shao Hua Luo ◽  
Zi Long Tang ◽  
Hong Yun Li ◽  
Zhong Tai Zhang ◽  
Xi Zhou Xiong
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Nonlinear Coefficient ◽  
The Other ◽  
Optimal Composition ◽  
Low Loss ◽  
Nb Addition

The present work attempted to investigate the effect of Nb addition on the electrical properties of the (Ca,Si,Ce,Nb)-doped TiO2 ceramics. The content of added niobium is in the range 0.1-1.0mol %, while that of the other additives keeps constant. The results showed that an optimal composition doped with 0.8mol% Nb2O5, followed by sintering at 1350°C, was obtained with low V1 mA of 7.22V, high nonlinear coefficient of 5.76, ultrahigh dielectric constant (er = 86000) as well as relatively low loss (tgd = 0.52) in room temperature at 1 kHz. SEM studies show that change of niobium had significant influence on grain growth and micro structural characteristics of the sintered samples.

Generation of squeezed states in coupled cavity chains via dissipation of gap-tunable qubits

2014 ◽  
Vol 90 (4) ◽  
Author(s):  
Sheng-Li Ma ◽  
Zhen Li ◽  
Peng-Bo Li ◽  
Fu-Li Li
Keyword(s):  
Squeezed States ◽  
Coupled Cavity

scholarly journals Multidimensional Face Representation in a Deep Convolutional Neural Network Reveals the Mechanism Underlying AI Racism

2021 ◽  
Vol 15 ◽  
Author(s):  
Jinhua Tian ◽  
Hailun Xie ◽  
Siyuan Hu ◽  
Jia Liu
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Underlying Mechanism ◽  
Deep Convolutional Neural Network ◽  
The Other ◽  
Training Data ◽  
Identification Accuracy ◽  
Social Bias ◽  
Novel Approach ◽  
Ai Ethics

The increasingly popular application of AI runs the risk of amplifying social bias, such as classifying non-white faces as animals. Recent research has largely attributed this bias to the training data implemented. However, the underlying mechanism is poorly understood; therefore, strategies to rectify the bias are unresolved. Here, we examined a typical deep convolutional neural network (DCNN), VGG-Face, which was trained with a face dataset consisting of more white faces than black and Asian faces. The transfer learning result showed significantly better performance in identifying white faces, similar to the well-known social bias in humans, the other-race effect (ORE). To test whether the effect resulted from the imbalance of face images, we retrained the VGG-Face with a dataset containing more Asian faces, and found a reverse ORE that the newly-trained VGG-Face preferred Asian faces over white faces in identification accuracy. Additionally, when the number of Asian faces and white faces were matched in the dataset, the DCNN did not show any bias. To further examine how imbalanced image input led to the ORE, we performed a representational similarity analysis on VGG-Face's activation. We found that when the dataset contained more white faces, the representation of white faces was more distinct, indexed by smaller in-group similarity and larger representational Euclidean distance. That is, white faces were scattered more sparsely in the representational face space of the VGG-Face than the other faces. Importantly, the distinctiveness of faces was positively correlated with identification accuracy, which explained the ORE observed in the VGG-Face. In summary, our study revealed the mechanism underlying the ORE in DCNNs, which provides a novel approach to studying AI ethics. In addition, the face multidimensional representation theory discovered in humans was also applicable to DCNNs, advocating for future studies to apply more cognitive theories to understand DCNNs' behavior.

#3079 Investigating the feasibility of automating the differential diagnosis of transient loss of consciousness

2021 ◽  
Vol 92 (8) ◽  
pp. A7.1-A7
Author(s):  
Nathan Pevy ◽  
Heidi Christensen ◽  
Traci Walker ◽  
Markus Reuber
Keyword(s):  
Differential Diagnosis ◽  
Random Forest ◽  
Epileptic Seizures ◽  
The Other ◽  
Future Research ◽  
Loss Of Consciousness ◽  
Transient Loss Of Consciousness ◽  
Audio Recordings ◽  
Transient Loss ◽  
Nonepileptic Seizures

BackgroundThere are three common causes of Transient Loss of Consciousness (TLOC), syncope, epileptic and psychogenic nonepileptic seizures (PNES). Many individuals who have experienced TLOC initially receive an incorrect diagnosis and inappropriate treatment. Whereas syncope can be distinguished from the other two causes relatively easily with a small number of yes/no questions, the differentiation of the other two causes of TLOC is more challenging. Previous qualitative research based on the methodology of Conversation Analysis has demonstrated that epileptic and nonepileptic seizures are described differently when patients talk to clinicians about their TLOC experiences. One particularly prominent difference is that epileptic seizure descriptions are characterised by more formulation effort than accounts of nonepileptic seizures.AimThis research investigates whether features likely to reflect the level of formulation effort can be automatically elicited from audio recordings and transcripts of speech and used to differentiate between epileptic and nonepileptic seizures.MethodVerbatim transcripts of conversations between patients and neurologists were manually produced from video and audio recordings of interactions with 45 patients (21 epilepsy and24 PNES). The subsection of each transcript containing the patients account of their first seizure was manually extracted for the analysis. Seven automatically detectable features were designed as markers of formulation effort. These features were used to train a Random Forest machine learning classifier.ResultsThere were significantly more hesitations and repetitions in descriptions of first epileptic than nonepileptic seizures. Using a nested leave-one-out cross validation approach, 71% of seizures were correctly classified by the Random Forest classifier.ConclusionsThis pilot study provides proof of principle that linguistic features that have been automatically extracted from audio recordings and transcripts could be used to distinguish between epileptic seizures and PNES and thereby contribute to the differential diagnosis of TLOC. Future research should explore whether additional observations can be incorporated into a diagnostic stratification tool. Moreover, future research should explore the performance of these features when they have been extracted from transcripts produced by automatic speech recognition and when they are combined with additional information provided by patients and witnesses about seizure manifestations and medical history.

scholarly journals Interaction of marine ice-sheet instabilities in two drainage basins: simple scaling of geometry and transition time

2015 ◽  
Vol 9 (2) ◽  
pp. 631-645 ◽  
Author(s):  
J. Feldmann ◽  
A. Levermann
Keyword(s):  
Drainage Basin ◽  
Flow Line ◽  
Three Dimensional ◽  
Ice Sheet ◽  
Underlying Mechanism ◽  
The Other ◽  
Transition Time ◽  
Horizontal Extent ◽  
Central Surface ◽  
Successive Initiation

Abstract. The initiation of a marine ice-sheet instability (MISI) is generally discussed from the ocean side of the ice sheet. It has been shown that the reduction in ice-shelf buttressing and softening of the coastal ice can destabilize a marine ice sheet if the bedrock is sloping upward towards the ocean. Using a conceptional flow-line geometry, we investigate the possibility of whether a MISI can be triggered from the direction of the ice divide as opposed to coastal forcing and explore the interaction between connected basins. We find that the initiation of a MISI in one basin can induce a destabilization in the other. The underlying mechanism of basin interaction is based on dynamic thinning and a consecutive motion of the ice divide which induces a thinning in the adjacent basin and a successive initiation of the instability. Our simplified and symmetric topographic setup allows scaling both the geometry and the transition time between both instabilities. We find that the ice profile follows a universal shape that is scaled with the horizontal extent of the ice sheet and that the same exponent of 1/2 applies for the scaling relation between central surface elevation and horizontal extent as in the pure shallow ice approximation (Vialov profile). Altering the central bed elevation, we find that the extent of grounding-line retreat in one basin determines the degree of interaction with the other. Different scenarios of basin interaction are discussed based on our modeling results as well as on a conceptual flux-balance analysis. We conclude that for the three-dimensional case, the possibility of drainage basin interaction on timescales on the order of 1 kyr or larger cannot be excluded and hence needs further investigation.

Influence of steel fibres on friction behaviours with respect to speed, pressure and temperature

2017 ◽  
Vol 69 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Talib Ria Jaafar ◽  
Noor Iswadi Ismail ◽  
Mohd Fauzi Ismail ◽  
Eliasidi Abu Othman
Keyword(s):  
Surface Temperature ◽  
Steel Fibre ◽  
Applied Pressure ◽  
The Other ◽  
Brake Pad ◽  
Volume Percentage ◽  
Content Type ◽  
Pressure Surface ◽  
Two Samples ◽  
Braking Process

Purpose This study aims to investigate the effect of different volume percentage (Vol.%) of steel fibre on the pressure, surface temperature and speed sensitivity behaviour during braking process as known brake effectiveness and to propose the best steel fibre Vol.% in the formulation. Design/methodology/approach Three brake pads composed of three different steel fibre volume percentages were fabricated through powder metallurgy route. Selecting one sample as based formulations, steel fibre (Vol.%) was decreased and increased by 50 per cent in the other two samples, respectively. The other ingredients are proportionally increased and decreased accordingly to the base formulation. The samples were tested for determining their hardness, porosity and coefficient of friction (COF) using Rockwell hardness tester, hot bath and brake inertia dynamometer, respectively. Findings Test results indicated that Sample T1 which composed of 9 Vol.% of steel fibre had the lowest COF and was sensitive to applied pressure, surface temperature and speed. The samples which composed of 18 and 27 Vol.% of steel fibre were having the same trend of COF and were sensitive to surface temperature and speed. Sample T which composed of 18 Vol.% of steel fibre had lower brake pad and disc lost as compared to Sample T2 which composed of 27 Vol.%. Mechanical properties did not show any significant correlation with COF sensitivity with temperature, speed and pressure. Originality/value The sample with 18 Vol.% of steel fibre was found to be the best formulation which produced acceptable COF; less sensitive to temperature, pressure and speed during braking process; and better wear resistance of brake pad as well as the rotor.

scholarly journals The Role of Intestinal Dysbacteriosis Induced Arachidonic Acid Metabolism Disorder in Inflammaging in Atherosclerosis

2021 ◽  
Vol 11 ◽  
Author(s):  
Yingxin Sun ◽  
Danbin Wu ◽  
Wenyun Zeng ◽  
Yefei Chen ◽  
Maojuan Guo ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Intestinal Flora ◽  
Underlying Mechanism ◽  
Lesion Size ◽  
Arachidonic Acid Metabolism ◽  
The Other ◽  
Mucosal Barrier ◽  
Low Grade ◽  
Aged Mice

BackgroundAging induced chronic systemic inflammatory response is an important risk factor for atherosclerosis (AS) development; however, the detailed mechanism is yet to be elucidated.ObjectiveTo explore the underlying mechanism of how aging aggravates AS advancement.MethodsA young (five-week-old, YM) and aged group (32-week-old, OM) male apoE-/- mice with a high fat diet were used as models, and age-matched male wild-type C57BL/6J (WT) mice were used as controls. AS lesion size, serum lipid profile, cytokines, and gut microbiota-derived LPS were analyzed after 32 weeks of diet intervention. A correlation analysis between the 16S rRNA sequencing of the feces and serum metabolomics profiles was applied to examine the effect of their interactions on AS.ResultsApoE-/- mice developed severe atherosclerosis and inflammation in the aorta compared to the WT groups, and aged apoE-/- mice suffered from a more severe AS lesion than their younger counterparts and had low-grade systemic inflammation. Furthermore, increased levels of serum LPS, decreased levels of SCFAs production, as well as dysfunction of the ileal mucosal barrier were detected in aged mice compared with their younger counterparts. There were significant differences in the intestinal flora composition among the four groups, and harmful bacteria such as Lachnospiraceae_FCS020, Ruminococcaceae_UCG-009, Acetatifactor, Lachnoclostridium and Lactobacillus_gasseri were significantly increased in the aged apoE-/- mice compared with the other groups. Concurrently, metabolomics profiling revealed that components involved in the arachidonic acid (AA) metabolic pathway such as 20-HETE, PGF2α, arachidonic acid, and LTB4 were significantly higher in the aged AS group than in the other groups. This suggested that metabolic abnormalities and disorders of intestinal flora occurred in AS mice.ConclusionsAging not only altered the gut microbiome community but also substantially disturbed metabolic conditions. Our results confirm that AA metabolism is associated with the imbalance of the intestinal flora in the AS lesions of aged mice. These findings may offer new insights regarding the role of gut flora disorders and its consequent metabolite changed in inflammaging during AS development.

scholarly journals Multidimensional face representation in deep convolutional neural network reveals the mechanism underlying AI racism

2020 ◽  
Author(s):  
Jinhua Tian ◽  
Hailun Xie ◽  
Siyuan Hu ◽  
Jia Liu
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Underlying Mechanism ◽  
Deep Convolutional Neural Network ◽  
The Other ◽  
Identification Accuracy ◽  
Social Bias ◽  
Novel Approach ◽  
The Face ◽  
Ai Ethics

AbstractThe increasingly popular application of AI runs the risks of amplifying social bias, such as classifying non-white faces to animals. Recent research has attributed the bias largely to data for training. However, the underlying mechanism is little known, and therefore strategies to rectify the bias are unresolved. Here we examined a typical deep convolutional neural network (DCNN), VGG-Face, which was trained with a face dataset consisting of more white faces than black and Asian faces. The transfer learning result showed significantly better performance in identifying white faces, just like the well-known social bias in human, the other-race effect (ORE). To test whether the effect resulted from the imbalance of face images, we retrained the VGG-Face with a dataset containing more Asian faces, and found a reverse ORE that the newly-trained VGG-Face preferred Asian faces over white faces in identification accuracy. In addition, when the number of Asian faces and white faces were matched in the dataset, the DCNN did not show any bias. To further examine how imbalanced image input led to the ORE, we performed the representational similarity analysis on VGG-Face’s activation. We found that when the dataset contained more white faces, the representation of white faces was more distinct, indexed by smaller ingroup similarity and larger representational Euclidean distance. That is, white faces were scattered more sparsely in the representational face space of the VGG-Face than the other faces. Importantly, the distinctiveness of faces was positively correlated with the identification accuracy, which explained the ORE observed in the VGG-Face. In sum, our study revealed the mechanism underlying the ORE in DCNNs, which provides a novel approach of study AI ethics. In addition, the face multidimensional representation theory discovered in human was found also applicable to DCNNs, advocating future studies to apply more cognitive theories to understand DCNN’s behavior.

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