scholarly journals Statics and Dynamics of V-shaped Micro-beams Under Axial Forces

2021 ◽  
Author(s):  
Hassen Ouakad ◽  
Nouha Alcheikh ◽  
Sofiane Ben Mbarek ◽  
Rodrigo Rocha ◽  
Mohammad Younis
Keyword(s):  
High Performance ◽  
Axial Loads ◽  
Electrostatically Actuated ◽  
High Tunability ◽  
Axial Forces ◽  
Initial Rise ◽  
Statics And Dynamics ◽  
Static Equation ◽  
Dc Bias

Abstract We present an investigation into the static and dynamic behaviors of electrostatically actuated in-plane micro-electro-mechanical V-shaped micro-beam under axial loads. The micro-beams are actuated with two separate electrodes of uniform air-gap across their length. The effects of the initial rise and DC bias voltage are examined while varying the axial loads ranging from compressive to tensile. The numerical analysis is based on a nonlinear equation of motion of a shallow V-shaped micro-beam. The static equation is solved using a reduced-order model based on the Galerkin procedure. Then, the eigenvalue problem of the structure is solved for various equilibrium positions. The analytical model is validated by comparing to an experimental case study. The results show rich and diverse static and dynamic behavior. It is shown that the micro-beam may exhibit only pull-in or snap-through and pull-in instabilities. Various multi-state and hysterics behaviors are demonstrated when varying the actuation forces and the initial rise. High tunability is demonstrated when varying the axial and DC loads for the first two symmetric vibration modes. Such rich behavior can be very useful for high performance micro-scale applications designs.

Statics and Dynamics of MEMS Arches Under Axial Forces

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Sami A. Alkharabsheh ◽  
Mohammad I. Younis
Keyword(s):  
Natural Frequency ◽  
Stable Operation ◽  
Electrostatic Forces ◽  
Order Model ◽  
Reduced Order ◽  
Electrostatically Actuated ◽  
Axial Forces ◽  
Compressive Loads ◽  
Statics And Dynamics ◽  
Static Equation

This works aims to investigate the effect of axial forces on the static behavior and the fundamental natural frequency of electrostatically actuated MEMS arches. The analysis is based on a nonlinear equation of motion of a shallow arch under axial and electrostatic forces. The static equation is solved using a reduced-order model based on the Galerkin procedure. The effects of the axial and electrostatic forces on the static response are examined. Then, the eigenvalue problem of the arch is solved for various equilibrium positions. Several results are shown for the variations of the natural frequency and equilibrium position of the arch under axial forces ranging from compressive loads beyond buckling to tensile loads and for voltage loads starting from small values to large values near the pull-in instability. It is found that the dynamics of MEMS arches are very sensitive to axial forces, which may be induced unintentionally through microfabrication processes or due to temperature variations while in use. On the other hand, it is shown that axial forces can be used deliberately to control the dynamics of MEMS arches to achieve desirable functions, such as extending their stable operation range and tuning their natural frequencies.

Air Bridge and Vertical Carbon Nanotube Switches for High Performance Switching Applications

2006 ◽  
Vol 924 ◽  
Author(s):  
Anupama B Kaul ◽  
Eric W Wong ◽  
Larry Epp ◽  
Michael J. Bronikowski ◽  
Brian D Hunt
Keyword(s):  
Carbon Nanotubes ◽  
High Performance ◽  
Si Substrate ◽  
Electrical Measurements ◽  
Metal Electrodes ◽  
Electrostatically Actuated ◽  
Switch Architecture ◽  
Low Mass ◽  
Heavily Doped ◽  
Dc Bias

ABSTRACTCarbon nanotubes are attractive for switching applications since electrostatically-actuated CNT switches have low actuation voltages and power requirements, while allowing GHz switching speeds that stem from the inherently high elastic modulus and low mass of the CNT. Our first NEM structure, the air-bridge switch, consists of suspended single-walled nanotubes (SWNTs) that lie above a sputtered Nb electrode. Electrical measurements of these air-bridge devices show well-defined ON and OFF states as a dc bias of a few volts is applied. The switches were measured to have switching times down to a few nanoseconds. Our second NEM structure, the vertical CNT switch, consists of nanotubes grown perpendicular to the substrate. Vertical multi-walled nanotubes (MWNTs) are grown directly on a heavily doped Si substrate, from 200 − 300 nm wide, ∼ 1 μm deep nano-pockets, with Nb metal electrodes to result in the formation of a vertical single-pole-double-throw CNT switch architecture.

scholarly journals The Effects of Initial Rise and Axial Loads on MEMS Arches

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
S. A. Tella ◽  
A. Z. Hajjaj ◽  
M. I. Younis
Keyword(s):  
Axial Load ◽  
Eigenvalue Problems ◽  
Recent Experimental Data ◽  
Axial Loads ◽  
Resonant Frequencies ◽  
The Past ◽  
Initial Rise ◽  
Resonance Frequencies ◽  
Initial Decrease

Arch microbeams have been utilized and proposed for many uses over the past few years due to their large tunability and bistability. However, recent experimental data have shown different mechanical behaviors of arches when subjected to axial loads, i.e., their stiffness may increase or decrease with applied axial loads. This paper aims to investigate in depth, the influence of the competing effects of initial rise and axial loads on the mechanical behavior of micromachined arches; mainly their static deflection and resonant frequencies. Based on analytical solutions, the static response and eigenvalue problems are analyzed for various values of initial rises and axial loads. Universal curves showing the variation of the first three resonance frequencies of the arch are generated for various values of initial rise under both tensile and compressive axial loads. This study shows that increasing the tensile or compressive axial loads for different values of initial rise may lead to either increase in the stiffness of the beam or initial decrease in the stiffness, which later increases as the axial load is increased depending on the dominant effect of the initial rise of the arch and the axial load. The obtained universal curves represent useful design tools to predict the tunability of arches under axial loads for various values of initial rises. The use of the universal curves is demonstrated with an experimental case study. Analytical formulation is developed to predict the point of minimum where the trend of the resonance frequency versus axial loads changes qualitatively due to the competing effects of axial loads and initial curvature.

THE USE OF CASE STUDY METHOD IN TEACHING THE TERMINOLOGY IN THE FIELD OF AGRICULTURAL MACHINERY

2019 ◽  
pp. 123-130
Keyword(s):  
Case Studies ◽  
High Performance ◽  
Mechanical Engineering ◽  
The United States ◽  
Machine Building ◽  
Soil Tillage ◽  
Case Study Method ◽  
Agricultural Machine ◽  
Manufacturing Machine

The scientific research works concerning the field of mechanical engineering such as, manufacturing machine slate, soil tillage, sowing and harvesting based on the requirements for the implementation of agrotechnical measures for the cultivation of plants in its transportation, through the development of mastering new types of high-performance and energy-saving machines in manufacturing machine slate, creation of multifunctional machines, allowing simultaneous soil cultivation, by means of several planting operations, integration of agricultural machine designs are taken into account in manufacturing of the local universal tractor designed basing on high ergonomic indicators. For this reason, this article explores the use of case studies in teaching agricultural terminology by means analyzing the researches in machine building. Case study method was firstly used in 1870 in Harvard University of Law School in the United States. Also in the article, we give the examples of agricultural machine-building terms, teaching terminology and case methods, case study process and case studies method itself. The research works in the field of mechanical engineering and the use of case studies in teaching terminology have also been analyzed. In addition, the requirements for the development of case study tasks are given in their practical didactic nature. We also give case study models that allow us analyzing and evaluating students' activities.

scholarly journals Neighborhood Energy Modeling and Monitoring: A Case Study

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3716
Author(s):  
Francesco Causone ◽  
Rossano Scoccia ◽  
Martina Pelle ◽  
Paola Colombo ◽  
Mario Motta ◽  
...  
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Early Stage ◽  
Energy Performance ◽  
Monitoring Plan ◽  
Performance Targets ◽  
Carrier Energy ◽  
Zero Carbon ◽  
Energy Grid

Cities and nations worldwide are pledging to energy and carbon neutral objectives that imply a huge contribution from buildings. High-performance targets, either zero energy or zero carbon, are typically difficult to be reached by single buildings, but groups of properly-managed buildings might reach these ambitious goals. For this purpose we need tools and experiences to model, monitor, manage and optimize buildings and their neighborhood-level systems. The paper describes the activities pursued for the deployment of an advanced energy management system for a multi-carrier energy grid of an existing neighborhood in the area of Milan. The activities included: (i) development of a detailed monitoring plan, (ii) deployment of the monitoring plan, (iii) development of a virtual model of the neighborhood and simulation of the energy performance. Comparisons against early-stage energy monitoring data proved promising and the generation system showed high efficiency (EER equal to 5.84), to be further exploited.

Hardware Accelerator Integration Tradeoffs for High-Performance Computing: A Case Study of GEMM Acceleration in N-Body Methods

2021 ◽  
Vol 32 (8) ◽  
pp. 2035-2048
Author(s):  
Mochamad Asri ◽  
Dhairya Malhotra ◽  
Jiajun Wang ◽  
George Biros ◽  
Lizy K. John ◽  
...  
Keyword(s):  
High Performance Computing ◽  
High Performance ◽  
Hardware Accelerator ◽  
Performance Computing

scholarly journals To separate or not to separate: what is necessary and enough for a green and sustainable extraction of bioactive compounds from Brazilian citrus waste

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Vânia G. Zuin ◽  
Luize Z. Ramin ◽  
Mateus L. Segatto ◽  
Aylon M. Stahl ◽  
Karine Zanotti ◽  
...  
Keyword(s):  
High Performance ◽  
Orange Peel ◽  
Solvent Ratio ◽  
Biomass Waste ◽  
Chemical Profiles ◽  
Orange Waste ◽  
Sustainable Materials ◽  
Citrus Waste ◽  
Sustainable Extraction

AbstractIncreasing demands to obtain chemicals via greener and more sustainable materials and processes introduces concepts that should be considered and applied from lab to larger scales. Obtaining bioactive chemicals from agro-industrial non-food biomass waste can combine benign techniques and bio-circular economy to reach this goal. After extraction, evaluating profitability and environmental impacts to decide whether separation – and to what extent – is necessary or not is indispensable. This could be integrated into an approach known as sufficiency, as an important criterion for sustainability. From this perspective, Brazil’s annual generation of 8 million tons of orange waste is relevant, since citrus waste has large amounts of high-value compounds, such as pectin, d-limonene and flavonoids. This case study aimed at developing and comparing green and sustainable analytical methods to obtain flavonoids from orange peel. Homogenizer, ultrasound and microwave-assisted extractions were employed using chemometric tools, considering time, sample/solvent ratio, temperature and ethanol concentration as variables to obtain extracts containing hesperidin, naringenin, hesperetin and nobiletin. The bioactive flavonoids were determined by high-performance liquid chromatography (HPLC-UV). Microwave extraction was the most efficient method for obtaining the majority of flavonoids studied, six times more for hesperidin. Moreover, orange waste from different farming models showed diverse chemical profiles showing the importance of this alternative in natural product resources.

SURVEILLANCE OF DIABETES PREVALENCE RATE THROUGH THE DEVELOPMENT OF A MARKOV-BASED CONTROL CHART

2012 ◽  
Vol 12 (04) ◽  
pp. 1250083
Author(s):  
PERSHANG DOKOUHAKI ◽  
RASSOUL NOOROSSANA
Keyword(s):  
Control Chart ◽  
Control Charts ◽  
High Performance ◽  
Discrete Data ◽  
Correlated Data ◽  
Statistical Process ◽  
Control Charting ◽  
Attribute Quality ◽  
Related Process

In the field of statistical process control (SPC), usually two issues are addressed; the variables and the attribute quality characteristics control charting. Focusing on discrete data generated from a process to be monitored, attributes control charts would be useful. The discrete data could be classified into two categories; the independent and auto-correlated data. Regarding the independence in the sequence of discrete data, the typical Shewhart-based control charts, such as p-chart and np-chart would be effective enough to monitor the related process. But considering auto-correlation in the sequence of the data, such control charts would not workanymore. In this paper, considering the auto-correlated sequence of X1, X2,…, Xt,… as the sequence of zeros or ones, we have developed a control chart based on a two-state Markov model. This control chart is compared with the previously developed charts in terms of the average number of observations (ANOS) measure. In addition, a case study related to the diabetic people is investigated to demonstrate the applicability and high performance of the developed chart.

scholarly journals Scientific Programming with High Performance Fortran: A Case Study Using the xHPF Compiler

1997 ◽  
Vol 6 (1) ◽  
pp. 127-152
Author(s):  
Eric De Sturler ◽  
Volker Strumpen
Keyword(s):  
High Performance ◽  
Parallel Implementation ◽  
Gaussian Elimination ◽  
Primary Objective ◽  
Matrix Product ◽  
Dense Matrix ◽  
High Performance Fortran ◽  
Partial Pivoting ◽  
Intel Paragon

Recently, the first commercial High Performance Fortran (HPF) subset compilers have appeared. This article reports on our experiences with the xHPF compiler of Applied Parallel Research, version 1.2, for the Intel Paragon. At this stage, we do not expect very High Performance from our HPF programs, even though performance will eventually be of paramount importance for the acceptance of HPF. Instead, our primary objective is to study how to convert large Fortran 77 (F77) programs to HPF such that the compiler generates reasonably efficient parallel code. We report on a case study that identifies several problems when parallelizing code with HPF; most of these problems affect current HPF compiler technology in general, although some are specific for the xHPF compiler. We discuss our solutions from the perspective of the scientific programmer, and presenttiming results on the Intel Paragon. The case study comprises three programs of different complexity with respect to parallelization. We use the dense matrix-matrix product to show that the distribution of arrays and the order of nested loops significantly influence the performance of the parallel program. We use Gaussian elimination with partial pivoting to study the parallelization strategy of the compiler. There are various ways to structure this algorithm for a particular data distribution. This example shows how much effort may be demanded from the programmer to support the compiler in generating an efficient parallel implementation. Finally, we use a small application to show that the more complicated structure of a larger program may introduce problems for the parallelization, even though all subroutines of the application are easy to parallelize by themselves. The application consists of a finite volume discretization on a structured grid and a nested iterative solver. Our case study shows that it is possible to obtain reasonably efficient parallel programs with xHPF, although the compiler needs substantial support from the programmer.

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