Electron wave diffraction by semiconductor gratings: Rigorous analysis and design parameters

1991 ◽  
Vol 59 (4) ◽  
pp. 440-442 ◽  
Author(s):  
Gregory N. Henderson ◽  
Elias N. Glytsis ◽  
Thomas K. Gaylord
2020 ◽  
Vol 14 ◽  
Author(s):  
Osama Bedair

Background: Modular steel buildings (MSB) are extensively used in petrochemical plants and refineries. Limited guidelines are available in the industry for analysis and design of (MSB) subject to accidental vapor cloud explosions (VCEs). Objectives: The paper presents simplified engineering model for modular steel buildings (MSB) subject to accidental vapor cloud explosions (VCEs) that are extensively used in petrochemical plants and refineries. Method: A Single degree of freedom (SDOF) dynamic model is utilized to simulate the dynamic response of primary building components. Analytical expressions are then provided to compute the dynamic load factors (DLF) for critical building elements. Recommended foundation systems are also proposed to install the modular building with minimum cost. Results: Numerical results are presented to illustrate the dynamic response of (MSB) subject to blast loading. It is shown that (DLF)=1.6 is attained at (td/t)=0.4 for front wall (W1) with (td/T)=1.25. For side walls (DLF)=1.41 and is attained at (td/t)=0.6. Conclusions: The paper presented simplified tools for analysis and design of (MSB) subject accidental vapor cloud blast explosions (VCEs). The analytical expressions can be utilized by practitioners to compute the (MSB) response and identify the design parameters. They are simple to use compared to Finite Element Analysis.


Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1329
Author(s):  
Jung Seok Lee ◽  
Gwan Hui Lee ◽  
Wahab Mohyuddin ◽  
Hyun Chul Choi ◽  
Kang Wook Kim

Analysis and design of an ultra-wideband microstrip-to-slotline transition on a low permittivity substrate is presented. Cross-sectional structures along the proposed transition are analyzed using conformal mapping assuming quasi-TEM modes, attaining one analytical line impedance formula with varying design parameters. Although the slotline is a non-TEM transmission line, the transitional structures are configured to have quasi-TEM modes before forming into the slotline. The line impedance is optimally tapered using the Klopfenstein taper, and the electric field shapes are smoothly transformed from microstrip line to slotline. The analytical formula is accurate within 5% difference, and the final transition configuration can be designed without parameter tuning. The implemented microstrip-to-slotline transition possesses insertion loss of less than 1.5 dB per transition and return loss of more than 10 dB from 4.4 to over 40 GHz.


Author(s):  
Paola Dalla Valle ◽  
Nick Thom

Abstract This paper presents the results of a review on variability of key pavement design input variables (asphalt modulus and thickness, subgrade modulus) and assesses effects on pavement performance (fatigue and deformation life). Variability is described by statistical terms such as mean and standard deviation and by its probability density distribution. The subject of reliability in pavement design has pushed many highway organisations around the world to review their design methodologies, mainly empirical, to move towards mechanistic-empirical analysis and design which provide the tools for the designer to evaluate the effect of variations in materials on pavement performance. This research has reinforced this need for understanding how the variability of design parameters affects the pavement performance. This study has only considered flexible pavements. The sites considered for the analysis, all in the UK (including Northern Ireland), were mainly motorways or major trunk roads. Pavement survey data analysed were for Lane 1, the most heavily trafficked lane. Sections 1km long were considered wherever possible. Statistical characterisation of the variation of layer thickness, asphalt stiffness and subgrade stiffness is addressed. A sensitivity analysis is then carried out to assess which parameter(s) have the greater influence on the pavement life. The research shows that, combining the effect of all the parameters considered, the maximum range of 15th and 85th percentiles (as percentages of the mean) was found to be 64% to 558% for the fatigue life and 94% to 808% for the deformation life.


2021 ◽  
Author(s):  
Samuel Yuguru

Abstract Physics in general is successfully governed by quantum mechanics at the microscale and principles of relativity at the macroscale. Any attempts to unify them using conventional methods have somewhat remained elusive for nearly a century up to the present stage. Here in this study, a classical gedanken experiment of electron-wave diffraction of a single slit is intuitively examined for its quantized states. A unidirectional monopole field as quanta of the electric field is pictorially conceptualized into 4D space-time. Its application towards quantum mechanics and general relativity in accordance with existing knowledge in physics paves an alternative path towards their reconciliation process. This assumes a multiverse at a hierarchy of scales with gravity localized to a body into space. Principles of special relativity are then sustained along inertia frames of extra dimensions within the proposed model. Such descriptions provide an approximate intuitive tool to examine physics in general from alternative perspectives using conventional methods and this warrants further investigations.


2020 ◽  
Author(s):  
Samuel Yuguru

Abstract Physics in general is successfully governed by quantum mechanics at the microscale and principles of relativity at the macroscale. Any attempts to unify them using conventional methods have somewhat remained elusive for nearly a century up to the present stage. Here in this study, a classical gedanken experiment of an electron-wave diffraction of a single slit is intuitively examined for its quantized states. A unidirectional monopole field as quanta of the electric field is pictorially conceptualized. Its application towards quantum mechanics and general relativity in consistent with existing knowledge in physics paves an alternative path towards their reconciliation process by assuming a multiverse at a hierarchy of scales. Such an outcome provides an approximate intuitive guide to pursue physics in general from alternative perspectives using conventional methods.


Author(s):  
H Kim ◽  
J Lee

This article investigates an optimal design for a paper-feeding system that minimizes both jamming and simultaneous feeding of multiple papers, hereafter referred to as the multi-feeding rate. A total of 11 design parameters for the paper transfer device, the paper separation device, and the paper guide path are selected and analysed in this study. A test jig for feeding and transferring papers is manufactured to obtain experimental data for use in parameter analysis and design optimization. Back-propagation neural network-based causality analysis is employed to extract five dominant variables among 11 design parameters, and the results of causality analysis are compared with sensitivity results obtained from the analysis of means in the context of experimental design. Five-variable, second-order polynomial based approximate meta-models for jam rate and multi-feeding rate are then constructed, and numerical optimization is performed using NSGA-II, a non-dominated sorting genetic algorithm. Finally, two numerical Pareto optimal solutions are verified via experimental testing.


Author(s):  
K. N. Song ◽  
B. S. Kang ◽  
K. H. Yoon ◽  
S. K. Choi ◽  
G. J. Park

Recently, much attention has been focused on the design of the fuel assemblies in the Pressurized Light Water Reactor (PLWR). The spacer grid is one of the main structural components in a fuel assembly. It supports fuel rods, guides cooling water, and maintains geometry from the external impact loads. In this research, a new shape of the spacer grid is designed by the axiomatic approach. The Independence Axiom is utilized for the design. For the conceptual design, functional requirements (FRs) are defined and corresponding design parameters (DPs) are found to satisfy FRs in sequence. Overall configuration and shapes are determined in this process. Detailed design is carried out based on the result of the axiomatic design. For the detailed design, the system performances are evaluated by using linear and nonlinear finite element analysis. The dimensions are determined by optimization. Some commercial codes are utilized for the analysis and design.


Author(s):  
Keychun Park ◽  
Geng Zhang ◽  
Matthew P. Castanier ◽  
Christophe Pierre

In this paper, a component-based parametric reduced-order modeling (PROM) technique for vibration analysis of complex structures is presented, and applications to both structural design optimization and uncertainty analysis are shown. In structural design optimization, design parameters are allowed to vary in the feasible design space. In probabilistic analysis, selected model parameters are assumed to have predefined probability distributions. For both cases, each realization corresponding to a specific set of parameter values could be evaluated accurately based on the exact modes for the system with those parametric values. However, as the number of realizations increases, this approach becomes prohibitively expensive, especially for largescale finite element models. Recently, a PROM method that employs a fixed projection basis was introduced to avoid the eigenanalysis for each variation while retaining good accuracy. The fixed basis is comprised of a combination of selected mode sets of the full model calculated at only a few sampling points in the parameter space. However, the preparation for the basis may still be cumbersome, and the simulation cost and the model size increase rapidly as the number of parameters increases. In this work, a component-based approach is taken to improve the efficiency and effectiveness of the PROM technique. In particular, a component mode synthesis method is employed so that the parameter changes are captured at the substructure level and the analysis procedure is accelerated. Numerical results are presented for two example problems, a design optimization of a pickup truck and a probabilistic analysis of a simple L-shaped plate. It is shown that the new component-based approach significantly improves the efficiency of the PROM technique.


Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1949
Author(s):  
Alessandro Catania ◽  
Mattia Cicalini ◽  
Michele Dei ◽  
Massimo Piotto ◽  
Paolo Bruschi

The design of single-stage OTAs for accurate switched-capacitor circuits involves challenging trade-offs between speed and power consumption. The addition of a Slew-Rate Enhancer (SRE) circuit placed in parallel to the main OTA (parallel-type SRE) constitutes a viable solution to reduce the settling time, at the cost of low-power overhead and no modifications of the main OTA. In this work, a practical analytical model has been developed to predict the settling time reduction achievable with OTA/SRE systems and to show the effect of the various design parameters. The model has been applied to a real case, consisting of the combination of a standard folded-cascode OTA with an existing parallel-type SRE solution. Simulations performed on a circuit designed with a commercial 180-nm CMOS technology revealed that the actual settling-time reduction was significantly smaller than predicted by the model. This discrepancy was explained by taking into account the internal delays of the SRE, which is exacerbated when a high output current gain is combined with high power efficiency. To overcome this problem, we propose a simple modification of the original SRE circuit, consisting in the addition of a single capacitor which temporarily boosts the OTA/SRE currents reducing the internal turn-on delay. With the proposed approach a settling-time reduction of 57% has been demonstrated with an SRE that introduces only a 10% power-overhead with respect of the single OTA solution. The robustness of the results have been validated by means of Monte-Carlo simulations.


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