Multiple Quantum Barrier Nano-avalanche Photodiodes - Part III: Time and Frequency Responses

2019 ◽  
Vol 9 (2) ◽  
pp. 192-197
Author(s):  
Somrita Ghosh ◽  
Aritra Acharyya
Keyword(s):  
Optical Pulse ◽  
Pulse Current ◽  
Avalanche Photodiodes ◽  
Simulation Method ◽  
Rectangular Pulse ◽  
Operating Conditions ◽  
Multiple Quantum ◽  
Material System ◽  
Frequency Responses ◽  
The Fourier Transform

Background: The time and frequency responses of Multiple Quantum Barrier (MQB) nano-scale Avalanche Photodiodes (APDs) based on Si~3C-SiC material system have been investigated in this final part. Methods: A very narrow rectangular pulse of pulse-width of 0.4 ps has been used as the input optical pulse having 850 nm wavelength incidents on the p+-side of the MQB APD structures and corresponding current responses have been calculated by using a simulation method developed by the authors. Results: Finally the frequency responses of the devices are obtained via the Fourier transform of the corresponding pulse current responses in time domain. Conclusion: Simulation results show that MQB nano-APDs possess significantly faster time response and wider frequency response as compared to the flat Si nano-APDs under similar operating conditions.

Multiple Quantum Barrier Nano-avalanche Photodiodes - Part I: Spectral Response

2019 ◽  
Vol 9 (2) ◽  
pp. 172-184
Author(s):  
Somrita Ghosh ◽  
Aritra Acharyya
Keyword(s):  
Optical Pulse ◽  
Near Infrared ◽  
Spectral Response ◽  
Avalanche Photodiodes ◽  
Operating Conditions ◽  
Excess Noise ◽  
Multiple Quantum ◽  
Material System ◽  
Frequency Responses ◽  
Noise Characteristics

Background: The spectral response of Multiple Quantum Barrier (MQB) nano-scale avalanche photodiodes (APDs) based on Si~3C-SiC material system shows considerable responsivity of the device within a very wide wavelength range which includes some portion of Ultra- Violet (UV) spectrum (200- 90 nm), visible spectrum (390-770 nm), near-infrared (700-1400 nm), short-wavelength infrared (1400-3000 nm) and mid-infrared (3000-4000 nm) wavelengths. It has already been concluded from preceding studies that Si~3C-SiC MQB APDs shows better spectral response and excess noise characteristics as compared to equivalent conventional APDs based on Si. Moreover, the superiority of the illumination through p+-side (ITPS) structure has been observed among two probable optical illumination configurations such as illumination through n+- side (ITNS) and illumination through p+-side (ITPS) structures. Methods: In this paper, the time and frequency responses of Si~3C-SiC MQB APDs have been investigated. A very narrow rectangular pulse of pulse-width of 0.4 ps has been used as the input optical pulse having 850 nm wavelength incident on the p+-side of the MQB APD structures (i.e. ITPS is considered here) and corresponding current responses have been calculated by using a rigorous simulation method developed by the authors; finally the frequency responses of the devices are obtained via the Fourier transform of the corresponding pulse current responses in time domain. Results: The width of the current responses are limited to 4.7 and 3.1 ps in Si nano-APD and Si~3C-SiC MQB (consisting of five quantum barriers) nano-APD respectively for the input optical pulse of width 0.4 ps of 850 nm wavelength. On the other hand, the 3 dB upper cut-off frequencies of the above-mentioned diodes are obtained to be 68.63 and 82.64 GHz respectively. Conclusion: Simulation results show that MQB nano-APDs possess significantly faster time response and wider frequency response as compared to the flat Si nano-APDs under similar operating conditions.

Efficient Simulation of Gear Contacts Including Transient Elastohydrodynamic Effects

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Peter Fietkau ◽  
Bernd Bertsche
Keyword(s):  
Three Dimensional ◽  
Direct Determination ◽  
Simulation Method ◽  
Elastic Half Space ◽  
Operating Conditions ◽  
Multibody Simulation ◽  
Multibody Model ◽  
Gear Contact ◽  
Oil Films ◽  
Lubrication Conditions

This paper describes an efficient transient elastohydrodynamic simulation method for gear contacts. The model uses oil films and elastic deformations directly in the multibody simulation, and is based on the Reynolds equation including squeeze and wedge terms as well as an elastic half-space. Two transient solutions to this problem, an analytical and a numerical one, were developed. The analytical solution is accomplished using assumptions for the gap shape and the pressure in the middle of the gap. The numerical problem is solved using multilevel multi-integration algorithms. With this approach, tooth impacts during gear rattling as well as highly loaded power-transmitting gear contacts can be investigated and lubrication conditions like gap heights or type of friction may be determined. The method was implemented in the multibody simulation environment SIMPACK. Therefore it is easy to transfer the developed element to other models and use it for a multitude of different engineering problems. A detailed three-dimensional elastic multibody model of an experimental transmission is used to validate the developed method. Important values of the gear contact like normal and tangential forces, proportion of dry friction, and minimum gap heights are calculated and studied for different conditions. In addition, pressure distributions on tooth flanks as well as gap forms are determined based on the numerical solution method. Finally, the simulation approach is validated with measurements and shows good consistency. The simulation model is therefore capable of predicting transient gear contact under different operating conditions such as load vibrations or gear rattling. Simulations of complete transmissions are possible and therefore a direct determination of transmission vibration behavior and structure-borne noise as well as of forces and lubrication conditions can be done.

MBE growth and characterization of doped multiple quantum well avalanche photodiodes

1997 ◽  
Vol 175-176 ◽  
pp. 983-989 ◽  
Author(s):  
H.M. Menkara ◽  
R.N. Bicknell-Tassius ◽  
R. Benz ◽  
C.J. Summers
Keyword(s):  
Quantum Well ◽  
Avalanche Photodiodes ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Mbe Growth

scholarly journals High Performance Multistring Converter Topology for Three-Phase Grid Tied 200 kW Photovoltaic Generating System

2017 ◽  
Vol 1 (2) ◽  
Author(s):  
Mohammad Rustam M. L. ◽  
F. Danang Wijaya
Keyword(s):  
Power Efficiency ◽  
High Performance ◽  
Reactive Power ◽  
Simulation Method ◽  
Operating Conditions ◽  
Total System ◽  
Voltage Reference ◽  
Pv System ◽  
Three Phase ◽  
Converter Topology

Under various external conditions, grid connected PV system performance is strongly affected by the topology that is used to connect a PV system with grid. This research aims to design a multistring based converter topology for three-phase grid connected 200 kW PV system that has a high performance in various operating conditions. Research was done by a simulation method using Matlab-Simulink with performance being evaluated including the generated power, efficiency, power quality in accordance with grid requirements, as well as the power flow. In the simulation, multistring converter topology was designed using two dc-dc boost multistring converters connected in parallel to a centralized of three-phase three-level NPC inverter with the size of the string being shorter and more parallel strings as well as the maximum voltage of the PV array of 273.5 V close to dc voltage reference of 500 V. Each dc-dc boost multistring converter have individual MPPT controllers. The simulation results showed that this multistring converter topology had a high performance in various operating conditions. This due to more power generated by the NPC inverter (> 190 kW) at the time of high power generation on the STC conditions (1000 W/m2, 25 oC), the lowest efficiency of the total system is 95.08 % and the highest efficiency of the total system is 99.4 %, the quality of the power generated in accordance with the requirements of grid, as well as the inverter put more active power to the grid and less reactive power to the grid. The response of the inverter slightly worse for loads with greater reactive power and unbalanced.

A Deep Neural Network Model for Learning Runtime Frequency Response Function Using Sensor Measurements

2021 ◽  
Author(s):  
Yongzhi Qu ◽  
Gregory W. Vogl ◽  
Zechao Wang
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Fourier Transform ◽  
Time Domain ◽  
Frequency Response Function ◽  
Frequency Component ◽  
Operating Conditions ◽  
Input Output ◽  
The Fourier Transform ◽  
The Time Domain

Abstract The frequency response function (FRF), defined as the ratio between the Fourier transform of the time-domain output and the Fourier transform of the time-domain input, is a common tool to analyze the relationships between inputs and outputs of a mechanical system. Learning the FRF for mechanical systems can facilitate system identification, condition-based health monitoring, and improve performance metrics, by providing an input-output model that describes the system dynamics. Existing FRF identification assumes there is a one-to-one mapping between each input frequency component and output frequency component. However, during dynamic operations, the FRF can present complex dependencies with frequency cross-correlations due to modulation effects, nonlinearities, and mechanical noise. Furthermore, existing FRFs assume linearity between input-output spectrums with varying mechanical loads, while in practice FRFs can depend on the operating conditions and show high nonlinearities. Outputs of existing neural networks are typically low-dimensional labels rather than real-time high-dimensional measurements. This paper proposes a vector regression method based on deep neural networks for the learning of runtime FRFs from measurement data under different operating conditions. More specifically, a neural network based on an encoder-decoder with a symmetric compression structure is proposed. The deep encoder-decoder network features simultaneous learning of the regression relationship between input and output embeddings, as well as a discriminative model for output spectrum classification under different operating conditions. The learning model is validated using experimental data from a high-pressure hydraulic test rig. The results show that the proposed model can learn the FRF between sensor measurements under different operating conditions with high accuracy and denoising capability. The learned FRF model provides an estimation for sensor measurements when a physical sensor is not feasible and can be used for operating condition recognition.

Numerical simulations of non-stationary distributions of electrochemical potentials in SOFC

2017 ◽  
Vol 34 (6) ◽  
pp. 1956-1988 ◽  
Author(s):  
Mayu Muramatsu ◽  
Keiji Yashiro ◽  
Tatsuya Kawada ◽  
Kenjiro Tarada
Keyword(s):  
Steady State ◽  
Numerical Simulations ◽  
Chemical Potential ◽  
Simulation Method ◽  
Open Circuit ◽  
Operating Conditions ◽  
Stationary Distributions ◽  
Experimental Conditions ◽  
Content Type ◽  
Numerical Examples

Purpose The purpose of this study is to develop a simulation method to calculate non-stationary distributions of the chemical potential of oxygen in a solid oxide fuel cell (SOFC) under operation. Design/methodology/approach The initial-boundary value problem was appropriately formulated and the appropriate boundary conditions were implemented so that the problem of non-stationary behavior of SOFC can be solved in accordance with actual operational and typical experimental conditions. The dependencies of the material properties on the temperature and partial pressure of oxygen were also elaborately introduced to realize actual material responses. The capability of the proposed simulation method was demonstrated under arbitrary operating conditions. Findings The steady state calculated with the open circuit voltage condition was conformable with the analytical solution. In addition, the transient states of the spatial distributions of potentials and currents under the voltage- and current-controlled conditions were successfully differentiated, even though they eventually became the same steady state. Furthermore, the effects of dense materials assumed for interconnects and current collectors were found to not be influential. It is thus safe to conclude that the proposed method enables us to simulate any type of transient simulations regardless of controlling conditions. Practical implications Although only uniaxial models were tested in the numerical examples in this paper, the proposed method is applicable for arbitrary shapes of SOFC cells. Originality/value The value of this paper is that adequate numerical simulations by the proposed method properly captured the electrochemical transient transport phenomena in SOFC under various operational conditions, and that the applicability was confirmed by some numerical examples.

The X-bar control chart with restriction of the capability indices

2017 ◽  
Vol 34 (1) ◽  
pp. 38-52 ◽  
Author(s):  
Pedro Carlos Oprime ◽  
Glauco Henrique de Sousa Mendes
Keyword(s):  
Phase I ◽  
Control Chart ◽  
Design Methodology ◽  
Simulation Method ◽  
Operating Conditions ◽  
Suggested Approach ◽  
Content Type ◽  
Capability Index ◽  
Simulation Techniques ◽  
Capability Indices

Purpose The purpose of this paper is to find the configuration of the number (m) and size (n) of the sample in Phase I that would make it possible to detect the out-of-control (OOC) state of the process with the smallest number of samples and ensure a capability index (Cpk) that would meet the customer’s requirements. Design/methodology/approach The suggested approach addresses this problem using simulation techniques and design of experiments (DOE). The simulation techniques made it possible to reproduce the normal operating conditions of the process. The DOE was used to construct a predictive model for control chart performance and thus to determine combinations of m and n in Phase I that would meet the capability objectives of the process. A numerical example and a simulation study were conducted to illustrate the proposed method. Findings Using simulation techniques and DOE, the authors can find the number (m) and size (n) of the sample in Phase I that would make it possible to detect the OOC state of the process with the smallest number of samples and ensure a Cpk that would meet the customer’s requirements. Originality/value In the real situations of many companies, choosing the numbers and sizes of samples (m and n) in Phases I and II is a crucial decision in relation to implementing a control chart. The paper shows that the simulation method and use of linear regression are effective alternatives because they are better known and more easily applied in industrial settings. Therefore, the need for alternatives to the X control chart comes into play.

Numerical Simulation Method Research on Pellet-Cladding Mechanical Interaction Based on ABAQUS Software

2020 ◽  
Author(s):  
Changbing Tang ◽  
Yongjun Jiao ◽  
Yuanming Li ◽  
Yi Zhou ◽  
Kun Zhang
Keyword(s):  
Performance Analysis ◽  
Contact Pressure ◽  
Nuclear Fuel ◽  
Local Stress ◽  
Simulation Method ◽  
Operating Conditions ◽  
Effective Control ◽  
Mechanical Interaction ◽  
Fuel Performance ◽  
Abaqus Software

Abstract The cladding acts as the first barrier to prevent the release of radioactive fission products, requiring its structural integrity to be maintained throughout the whole operation period of nuclear reactor. Therefore, cladding failure due to PCI (pellet claading mechanical interaction) should be avoided as much as possible in fuel design and operating conditions. At the same time, it is necessary to achieve effective control of the cladding stress by limiting the power growth rate etc. However, in the manufacturing process of fuel rod, the MPS (missing pellet surface) defect is inevitably generated. This defect may lead to a substantial increase in the local stress of the cladding, which in turn exceeds its corresponding stress limit, resulting in cladding failure. Accurate simulation of fuel performance caused by such defects will help prevent such failures. The traditional fuel performance analysis codes are based on a 1.5D analysis framework and cannot handle the local asymmetry problem of fuel such as the MPS defect. In order to accurately simulate the PCI phenomenon caused by the MPS defect, this research establishes a fuel performance analysis code based on the ABAQUS software and this code is suit for the 2D and 3D conditions. Based on the established analysis code, the irradiation-thermal-mechanical behavior of nuclear fuel under typical II transient conditions was studied, and the sensitivity analysis of the influence of different MPS sizes on the local stress of cladding was carried out. The simulation results show that :(1)the mises stress, contact pressure and equivalent creep strain of the cladding may be unevenly distributed due to the MPS defect.(2)the MPS defect will result in a more severe contact pressure on cladding during power transient period, which may lead to failure of cladding and should be prevented. The simulation method established in this research could be very help for the performance analysis for the nuclear fuel rods.

scholarly journals Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1909 ◽  
Author(s):  
András Poppe ◽  
Gábor Farkas ◽  
Lajos Gaál ◽  
Gusztáv Hantos ◽  
János Hegedüs ◽  
...  
Keyword(s):  
Thermal Environment ◽  
Light Emitting Diode ◽  
Virtual Prototyping ◽  
Multiple Quantum Well ◽  
Light Output ◽  
Operating Conditions ◽  
Domain Model ◽  
Multiple Quantum ◽  
Seamless Integration ◽  
Output Characteristics

This paper presents our approaches to chip level multi-domain LED (light emitting diode) modelling, targeting luminaire design in the Industry 4.0 era, to support virtual prototyping of LED luminaires through luminaire level multi-domain simulations. The primary goal of such virtual prototypes is to predict the light output characteristics of LED luminaires under different operating conditions. The key component in such digital twins of a luminaire is an appropriate multi-domain model for packaged LED devices that captures the electrical, thermal, and light output characteristics and their mutual dependence simultaneously and consistently. We developed two such models with this goal in mind that are presented in detail in this paper. The first model is a semi analytical, quasi black-box model that can be implemented on the basis of the built-in diode models of spice-like circuit simulators and a few added controlled sources. Our second presented model is derived from the physics of the operation of today’s power LEDs realized with multiple quantum well heterojunction structures. Both models have been implemented in the form of visual basic macros as well as circuit models suitable for usual spice circuit simulators. The primary test bench for the two circuit models was an LTspice simulation environment. Then, to support the design of different demonstrator luminaires of the Delphi4LED project, a spreadsheet application was developed, which ensured seamless integration of the two models with additional models representing the LED chips’ thermal environment in a luminaire. The usability of our proposed models is demonstrated by real design case studies during which simulated light output characteristics (such as hot lumens) were confirmed by luminaire level physical tests.

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