Nonlinear All-Optical Guided-Wave Devices: Operating Characteristics And Material Trade-Offs

1988 ◽  
Author(s):  
G I. Stegeman ◽  
E M. Wright ◽  
N Finlayson ◽  
R Zanoni ◽  
C T. Seaton ◽  
...  
Keyword(s):  
Guided Wave ◽  
Operating Characteristics ◽  
Trade Offs ◽  
All Optical

Optical properties of Quantum Disks: Real density matrix approach

Open Physics ◽  
2006 ◽  
Vol 4 (2) ◽  
Author(s):  
Gerard Czajkowski ◽  
Leonardo Silvestri
Keyword(s):  
Density Matrix ◽  
Guided Wave ◽  
Matrix Approach ◽  
Electron Hole ◽  
Optical Functions ◽  
Quantum Disk ◽  
All Optical ◽  
Quantum Disks ◽  
Analytical Expressions ◽  
Real Density

AbstractWe show how to compute the optical response of a Quantum Disk (QDisk) to an electromagnetic wave as a function of the incident wave polarization, in the energetic region of interband transitions. Both the TM and TE polarization in guided-wave geometry are analyzed. The method uses the microscopic calculation of Quantum Disk eigenfunctions and the macroscopic real density matrix approach to compute the effective QDisk susceptibility, taking into account the valence band structure of the QDisk material and the Coulomb interaction between the electron and the hole. Analytical expressions for the QDisk susceptibility are obtained for a certain model electron — hole potential. Using these expressions, all optical functions can be computed. Results for the absorption coefficient are computed for InAs/GaAs QDisks. Fair agreement with experiments is obtained.

Two-stage seamless transition design from open-label single-arm to randomized double-arm clinical trials

2016 ◽  
Vol 27 (1) ◽  
pp. 158-171 ◽  
Author(s):  
Haolun Shi ◽  
Guosheng Yin
Keyword(s):  
Clinical Trials ◽  
Sample Size ◽  
Phase Ii ◽  
Therapeutic Effects ◽  
Operating Characteristics ◽  
Phase Ii Trials ◽  
Open Label ◽  
Two Stage ◽  
Trade Offs ◽  
Experimental Drug

Conventional phase II clinical trials use either a single- or multi-arm comparison scheme to examine the therapeutic effects of the experimental drug. Both single- and multi-arm evaluations have their own merits; for example, single-arm phase II trials are easy to conduct and often require a smaller sample size, while multiarm trials are randomized and typically lead to a more objective comparison. To bridge the single- and double-arm schemes in one trial, we propose a two-stage design, in which the first stage takes a single-arm comparison of the experimental drug with the standard response rate (no concurrent treatment) and the second stage imposes a two-arm comparison by adding an active control arm. The design is calibrated using a new concept, the detectable treatment difference, to balance the trade-offs between futility termination, power, and sample size. We conduct extensive simulation studies to examine the operating characteristics of the proposed method and provide an illustrative example of our design.

All-optical tunable guided-wave thresholding with birefringent media

1994 ◽  
Vol 111 (1-2) ◽  
pp. 34-38 ◽  
Author(s):  
Juan P. Torres ◽  
Lluis Torner ◽  
Falk Lederer
Keyword(s):  
Guided Wave ◽  
All Optical

scholarly journals Development of a Food Image Recognition Algorithm Using Machine Learning

2020 ◽  
Author(s):  
Serge Assaad ◽  
Lawrence Carin ◽  
Anthony Joseph Viera
Keyword(s):  
Machine Learning ◽  
Food Choices ◽  
Recognition Algorithm ◽  
Machine Learning Techniques ◽  
Operating Characteristics ◽  
Food Items ◽  
Trade Offs ◽  
Learning Techniques ◽  
Food Image ◽  
Validation Set

Abstract Background: Researchers and consumers have limited options for objectively collecting or tracking data related to food choices. Objective: To develop and pilot test an algorithm that could accurately categorize food items from a meal photograph. Methods: We used a dataset of 7721 meal photographs taken by patrons in a cafeteria setting. We designed 22 broad categories recognizable by image that are parents of the original 1239 types of items in the photographs. We split the dataset into 3 mutually exclusive subsets: a training set (5250 images), a validation set (1312 images), and a test set (1159 images). Using a convolutional neural network and standard machine learning techniques, we tested the operating characteristics of the algorithm. Results: Salad recognition had the lowest specificity (0.74), while multiple categories had specificities close to 1.0 (e.g. cereals, pastries, sushi, yogurt). Areas under the ROC curve (AUCs), reflecting trade-offs between sensitivity and specificity, ranged from 0.73 (for yogurt) to 0.97 (for sushi). Conclusions: This work provides proof-of-concept for an algorithm that can categorize food items from a meal photograph.

scholarly journals Optimized design and performance analysis of a magnetic-field modulated brushless dual-mechanical port motor with Halbach array permanent magnets

2020 ◽  
Vol 12 (9) ◽  
pp. 168781402095775
Author(s):  
Ren He ◽  
Junmin Li
Keyword(s):  
Magnetic Field ◽  
Hybrid Electric Vehicle ◽  
Permanent Magnets ◽  
Structural Parameters ◽  
Torque Ripple ◽  
Parameters Optimization ◽  
Optimized Design ◽  
Operating Characteristics ◽  
Trade Offs ◽  
Halbach Array

In order to develop an electrical continuously variable transmission (E-CVT) to replace mechanical power coupling equipment applied in series-parallel hybrid electric vehicle (HEV), this paper proposes a magnetic-field modulated brushless dual-mechanical port motor with Halbach array permanent magnets, which has a more compact structure. The operating characteristics are analyzed by the lever analogy. It is concluded that the motor can realize the speed and torque decoupling between the engine and the wheel, which meet multi-mode operation requirements for HEV. To realize the multi-objective design of torque output, torque ripple and usage amount of permanent magnets, an optimization scheme combined parameter sensitivity with response surface methodology is adopted. The trade-offs among the optimization objectives are considered, then the key structural parameters and its optimal values are efficiently determined. Based on a two-dimensional model, the electromagnetic performances are simulated and analyzed. The results show that, after the parameters optimization, the no-load back electromotive force (EMF) has better sinusoidal characteristic, and the torque ripples and cogging torque peaks of the motor have been significantly reduced. Furthermore, a prototype motor is tested. The experimental results are consistent with the simulation results, which demonstrates the validity of the proposed structure and parameter optimization method.

Multiple Quantum Well Heterostructures Showing Optical Nonlinearities at Low Intensity and Fast Recovery

1998 ◽  
Vol 07 (01) ◽  
pp. 37-45 ◽  
Author(s):  
L. Gastaldi ◽  
C. Rigo ◽  
D. Campi ◽  
L. Faustini ◽  
C. Coriasso ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Optical Switching ◽  
Multiple Quantum Well ◽  
Optical Power ◽  
Guided Wave ◽  
Multiple Quantum ◽  
Photogenerated Carrier ◽  
Fast Recovery ◽  
All Optical ◽  
All Optical Switching

This paper focuses on photogenerated carrier nonlinearities in InGaAs/InAlAs quantum wells (QWs) that use low optical power, display a relatively fast recovery time (280 ps down to 35 ps), and excellent optical properties in terms of the sharpness of the absorption edge. A guided-wave, all-optical switching device is demonstrated as an application, at a wavelength which is of interest to telecommunication systems (1.55 μm) and requires low control energy (<0.3 pJ/pulse). A key issue here is that the controlled introduction of defects in the QW heterostructures allows the time response to be fastened significantly without being detrimental to the performance of the device in terms of on-off contrast and switching energy. The preparation procedure is compatible with metalorganic-based growth techniques widespread in optoelectronics at 1.55 μm.

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