An efficient design of dual-axis MEMS accelerometer considering microfabrication process limitations and operating environment variations

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Muhammad Ahmad Raza Tahir ◽  
Muhammad Mubasher Saleem ◽  
Syed Ali Raza Bukhari ◽  
Amir Hamza ◽  
Rana Iqtidar Shakoor
Keyword(s):  
Residual Stress ◽  
Operating Temperature ◽  
Design Approach ◽  
Design Parameters ◽  
Operating Pressure ◽  
Efficient Design ◽  
Content Type ◽  
Mems Accelerometer ◽  
Input Acceleration

PurposeThis paper aims to present an efficient design approach for the micro electromechanical systems (MEMS) accelerometers considering design parameters affecting the long-term reliability of these inertial sensors in comparison to traditional iterative microfabrication and experimental characterization approach. Design/methodology/approachA dual-axis capacitive MEMS accelerometer design is presented considering the microfabrication process constraints of the foundry process. The performance of the MEMS accelerometer is analyzed through finite element method– based simulations considering main design parameters affecting the long-term reliability. The effect of microfabrication process induced residual stress, operating pressure variations in the range of 10 mTorr to atmospheric pressure, thermal variations in the operating temperature range of −40°C to 100°C and impulsive input acceleration at different input frequency values is presented in detail. FindingsThe effect of residual stress is negligible on performance of the MEMS accelerometer due to efficient design of mechanical suspension beams. The effect of operating temperature and pressure variations is negligible on energy loss factor. The thermal strain at high temperature causes the sensing plates to deform out of plane. The input dynamic acceleration range is 34 g at room temperature, which decreases with operating temperature variations. At low frequency input acceleration, the input acts as a quasi-static load, whereas at high frequency, it acts as a dynamic load for the MEMS accelerometer. Originality/valueIn comparison with the traditional MEMS accelerometer design approaches, the proposed design approach focuses on the analysis of critical design parameters that affect the long-term reliability of MEMS accelerometer.

Design-airworthiness integration method for general aviation aircraft during early development stage

2019 ◽  
Vol 91 (7) ◽  
pp. 1067-1076
Author(s):  
Maxim Tyan ◽  
Jungwon Yoon ◽  
Nhu Van Nguyen ◽  
Jae-Woo Lee ◽  
Sangho Kim
Keyword(s):  
Design Optimization ◽  
Design Stage ◽  
Design Parameters ◽  
Design Framework ◽  
Efficient Design ◽  
Content Type ◽  
Early Design ◽  
Early Design Stage ◽  
Optimization Framework ◽  
Design Requirements

Purpose Major changes of an aircraft configuration are conducted during the early design stage. It is important to include the airworthiness regulations at this stage while there is extensive freedom for designing. The purpose of this paper is to introduce an efficient design framework that integrates airworthiness guidelines and documentation at the early design stage. Design/methodology/approach A new design and optimization process is proposed that logically includes the airworthiness regulations as design parameters and constraints by constructing a certification database. The design framework comprises requirements analysis, preliminary sizing, conceptual design synthesis and loads analysis. A design certification relation table (DCRT) describes the legal regulations in terms of parameters and values suitable for use in design optimization. Findings The developed framework has been validated and demonstrated for the design of a Federal Aviation Regulations (FAR) 23 four-seater small aircraft. The validation results show an acceptable level of accuracy to be applied during the early design stage. The total mass minimization problem has been successfully solved while satisfying all the design requirements and certification constraints specified in the DCRT. Moreover, successful compliance with FAR 23 subpart C is demonstrated. The proposed method is a useful tool for design optimization and compliance verifications during the early stages of aircraft development. Practical implications The new certification database proposed in this research makes it simpler for engineers to access a large amount of legal documentation related to airworthiness regulations and provides a link between the regulation text and actual design parameters and their bounds. Originality/value The proposed design optimization framework integrates the certification database that is built of several types of legal documents such as regulations, advisory circulars and standards. The Engineering Requirements and Guide summarizes all the documents and design requirements into a single document. The DCRT is created as a summary table that indicates the design parameters affected by a given regulation(s), the design stage at which the parameter can be evaluated and its value bounds. The introduction of the certification database into the design optimization framework significantly reduces the engineer’s load related for airworthiness regulations.

A generative design approach for modular construction in congested urban areas

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yuxi Wei ◽  
Hyungjoo Choi ◽  
Zhen Lei
Keyword(s):  
Urban Areas ◽  
Design Method ◽  
Residential Building ◽  
Information Modeling ◽  
Design Approach ◽  
Design Parameters ◽  
Building Structures ◽  
Modular Construction ◽  
Generative Design ◽  
Content Type

PurposeModular construction is widely adopted and used in the construction industry to improve construction performance with respect to both efficiency and productivity. The evaluation of design options for modular construction can be iterative, and thus automation is required to develop design alternatives. This research aims to explore the potential of utilizing the generative design approach to automate modular construction for residential building structures in urban areas such as New York City.Design/methodology/approachThe proposed research methodology is investigated for a systematic approach to parametrize design parameters for modular construction layout design as well as incorporate design rules/parameters into modularizing design layouts in a Building Information Modeling (BIM) environment. Based on current building codes and necessary inputs by the user, the proposed approach enables providing recommendations in a generative design method and optimizes construction processes by performing analytical calculations.FindingsThe generative design has been found to be efficient in generating layout designs for modular construction based on parametric design. The integration of BIM and generative design can allow industry practitioners to fast generate design layout with evaluations from constructability perspectives.Originality/valueThis paper has proposed a new approach of incorporating generative design with BIM technologies to solve module layout generations by considering design and constructability constraints. The method can be further extended for evaluating modular construction design from manufacturability and assembly perspectives.

Pantograph-catenary contact reliability analysis under crosswind

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yong-Hua Li ◽  
Yang Cao ◽  
Yong-Xin Wu ◽  
Xiao-Ning Bai ◽  
Jia-Wei Mao
Keyword(s):  
Relative Motion ◽  
Design Methodology ◽  
Effective Length ◽  
Design Parameters ◽  
Lateral Deviation ◽  
Vector Method ◽  
Content Type ◽  
Bird Swarm Algorithm ◽  
The Relationship

PurposeThis paper aims to establish the relationship between crosswind speed and pantograph-catenary lateral deviation, as well as quantify the influence of crosswind speed and rod size uncertainty on pantograph-catenary contact reliability.Design/methodology/approachThe closed vector method is used to establish the pantograph-catenary kinematics formula. A new prediction model is proposed by using the bird swarm algorithm to optimize the grey model. The lateral deviation of the pantograph and catenary is predicted via the new model. Then the relationship between the effective length of the rod and operating mileage is inferred by combining the effective length theory with the Gamma process, as well as the pantograph-catenary contact reliability model is established according to reliability theory.FindingsThe results obtained show the impacts of uncertainty design parameters of pantograph rods on pantograph-catenary contact reliability index, and the results at crosswind speed of 0 ms−1 and 5 ms−1 are 5.0630 and 4.1442, respectively. The reliability decreases with the increasing crosswind speed, and can be greater than the reliability calculated for rod size degradation due to long-term use.Originality/valueMost preceding works on pantograph-catenary contact reliability were based on principles of dynamics, without considering the pantograph-catenary relative motion. This research reveals the law of pantograph-catenary relative motion for uncertainty design parameters and crosswind, and quantifies the reliability from the angle of kinematics.

Application of fuzzy axiomatic design methodology for selection of design alternatives

2015 ◽  
Vol 13 (1) ◽  
pp. 2-22 ◽  
Author(s):  
S. Vinodh ◽  
V. Kamala ◽  
K. Jayakrishna
Keyword(s):  
Design Methodology ◽  
Material Selection ◽  
Axiomatic Design ◽  
Design Approach ◽  
Design Parameters ◽  
Content Type ◽  
Design Alternative ◽  
Design Alternatives ◽  
Practical Feasibility ◽  
Case Organization

Purpose – The purpose of this paper is to report a research conducted to apply fuzzy axiomatic design approach for selecting the design alternatives of an overflow valve. Design/methodology/approach – The approach started with the identification of functional requirements (FRs) and design parameters (DPs) and the relationship between them to select the best design alternative. Fuzzy analytical hierarchy process was used to calculate the weightage of FRs. The independence and information axioms were being deployed to validate the selection process. Findings – The most important FRs being identified include “improve manufacturability and adaptability”, “improve ease of operation” and “provide strength and reliability”. The most important DPs are design unification on washer and outlet valve, material selection for improving the strength and reliability and pressure change to check whether the valve is withstanding the pressure using flow analysis. The best design alternative (A1) which deals with material substitution is being implemented in the case organization. The proposed methodology also enables contemporary design engineers to effectively select the best design among a set of alternatives in a fuzzy environment. Research limitations/implications – This paper presents the application of fuzzy axiomatic design for selecting the best design alternative of an overflow valve. The identified best design is being subjected to implementation in the case organization. Practical implications – The industry decision makers were involved throughout the conduct of the study. Hence, the inferences derived from the study possess practical feasibility. Originality/value – The application of the fuzzy axiomatic design approach for selecting the best design alternative of an overflow valve is the original contribution of the authors. Also, the practical feasibility of the approach is also being exemplified.

Efficient Design on Body Strength and Capacitance of MLCC

2010 ◽  
Vol 156-157 ◽  
pp. 724-731
Author(s):  
Ching Ming Cheng ◽  
Yao Hsu ◽  
Wen Fang Wu
Keyword(s):  
Mechanical Strength ◽  
Empirical Equation ◽  
Design Approach ◽  
Design Stage ◽  
Design Parameters ◽  
Material Strength ◽  
Efficient Design ◽  
Material Test ◽  
Body Strength ◽  
Ceramic Capacitor

When designing the capacitance of a Multi-Layer Ceramic Capacitor (MLCC), engineers used to focus on the way to find appropriate combination of the design parameters. These design parameters usually include materials, layer numbers and thicknesses of the electrodes and the dielectrics. However, not considering the mechanical strength in the design stage may lead the manufactured MLCC prototypes to fail in material test, and a redesign is very often needed. Such a design-and-redesign process is inefficient and needs to be improved. The present paper proposes a simple and efficient design approach to replace the traditional one. It first identifies an empirical equation correlating the capacitance of a MLCC to the design parameters based on specifications. The strength of the MLCC can be evaluated in advance with the help of mechanics of material. A design platform which considers simultaneously the capacitance and the material strength under various design parameters can be established. Demonstration of a MLCC design by the developed platform indicates the proposed approach does help engineers improving and speeding their designs.

Design Optimization and Analysis of Proof Mass Actuation for MEMS Accelerometer: A Simulation Study

2017 ◽  
Vol 26 (06) ◽  
pp. 1750095 ◽  
Author(s):  
Vigneswaran Narayanamurthy ◽  
Sujatha Lakshminarayanan ◽  
S. Mohamed Yacin ◽  
Fahmi Samsuri
Keyword(s):  
Parallel Plate ◽  
Proof Mass ◽  
Design Parameters ◽  
Optimized Design ◽  
Efficient Design ◽  
Comb Drive ◽  
Mems Accelerometer ◽  
Mems Accelerometers ◽  
Acceleration Analysis ◽  
Cad Tool

In this paper, we present the design and analysis of the proof mass for capacitive based MEMS accelerometers. A study was done to determine the parameters (length of hinge and number of combs) to be optimized for the MEMS accelerometer design. The proposed design can measure the acceleration in [Formula: see text]-, [Formula: see text]- and [Formula: see text]-axes. The design features a proof mass with interdigitated fingers along each side. These interdigitated fingers act as parallel plate capacitors. Due to acceleration, capacitance changes along the comb drive. This change in capacitance can be used to monitor the acceleration. Analysis has been carried out with different comb width designs. Using the MEMS CAD tool CoventorWare, the structure has been designed, simulated and analyzed. The process flow for the fabrication has also been proposed for the above structure. Comparative study with several designs has been made and the efficient design parameters to be considered while designing MEMS accelerometer were proposed. Based on the study, a set of optimized design parameters for the comb accelerometer were reported.

Dual-isotope single-photon emission computerized tomography scanning in patients with glioblastoma multiforme: association with patient survival and histopathological characteristics of tumor after high-dose radiotherapy

1998 ◽  
Vol 89 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Richard B. Schwartz ◽  
B. Leonard Holman ◽  
Joseph F. Polak ◽  
Basem M. Garada ◽  
Marc S. Schwartz ◽  
...  
Keyword(s):  
Survival Rate ◽  
Glioblastoma Multiforme ◽  
Single Photon ◽  
Photon Emission ◽  
High Dose ◽  
Term Survival ◽  
Content Type ◽  
Dual Isotope ◽  
Fine Print

Object. The study was conducted to determine the association between dual-isotope single-photon emission computerized tomography (SPECT) scanning and histopathological findings of tumor recurrence and survival in patients treated with high-dose radiotherapy for glioblastoma multiforme. Methods. Studies in which SPECT with 201Tl and 99mTc-hexamethypropyleneamine oxime (HMPAO) were used were performed 1 day before reoperation in 47 patients with glioblastoma multiforme who had previously been treated by surgery and high-dose radiotherapy. Maximum uptake of 201Tl in the lesion was expressed as a ratio to that in the contralateral scalp, and uptake of 99mTc-HMPAO was expressed as a ratio to that in the cerebellar cortex. Patients were stratified into groups based on the maximum radioisotope uptake values in their tumor beds. The significance of differences in patient gender, histological characteristics of tissue at reoperation, and SPECT uptake group with respect to 1-year survival was elucidated by using the chi-square statistic. Comparisons of patient ages and time to tumor recurrence as functions of 1-year survival were made using the t-test. Survival data at 1 year were presented according to the Kaplan—Meier method, and the significance of potential differences was evaluated using the log-rank method. The effects of different variables (tumor type, time to recurrence, and SPECT grouping) on long-term survival were evaluated using Cox proportional models that controlled for age and gender. All patients in Group I (201Tl ratio < 2 and 99mTc-HMPAO ratio < 0.5) showed radiation changes in their biopsy specimens: they had an 83.3% 1-year survival rate. Group II patients (201T1 ratio < 2 and 99mTc-HMPAO ratio of ≥ 0.5 or 201Tl ratio between 2 and 3.5 regardless of 99mTc-HMPAO ratio) had predominantly infiltrating tumor (66.6%); they had a 29.2% 1-year survival rate. Almost all of the patients in Group III (201Tl ratio > 3.5 and 99mTc-HMPAO ratio ≥ 0.5) had solid tumor (88.2%) and they had a 6.7% 1-year survival rate. Histological data were associated with 1-year survival (p < 0.01); however, SPECT grouping was more closely associated with 1-year survival (p < 0.001) and was the only variable significantly associated with long-term survival (p < 0.005). Conclusions. Dual-isotope SPECT data correlate with histopathological findings made at reoperation and with survival in patients with malignant gliomas after surgical and high-dose radiation therapy.

Long-term management of patients with multiple brain metastases after shaped beam radiosurgery

2004 ◽  
pp. 406-412
Author(s):  
Paul Okunieff ◽  
Michael C. Schell ◽  
Russell Ruo ◽  
E. Ronald Hale ◽  
Walter G. O'Dell ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Tumor Control ◽  
Content Type ◽  
Negative Results ◽  
Multiple Metastases ◽  
Extracranial Disease ◽  
Successful Control ◽  
The Brain

✓ The role of radiosurgery in the treatment of patients with advanced-stage metastatic disease is currently under debate. Previous randomized studies have not consistently supported the use of radiosurgery to treat patients with numbers of brain metastases. In negative-results studies, however, intracranial tumor control was high but extracranial disease progressed; thus, patient survival was not greatly affected, although neurocognitive function was generally maintained until death. Because the future promises improved systemic (extracranial) therapy, the successful control of brain disease is that much more crucial. Thus, for selected patients with multiple metastases to the brain who remain in good neurological condition, aggressive lesion-targeting radiosurgery should be very useful. Although a major limitation to success of this therapy is the lack of control of extracranial disease in most patients, it is clear that well-designed, aggressive treatment substantially decreases the progression of brain metastases and also improves neurocognitive survival. The authors present the management and a methodology for rational treatment of a patient with breast cancer who has harbored 24 brain metastases during a 3-year period.

Spinal meningioma after treatment for Hodgkin disease

2001 ◽  
Vol 95 (2) ◽  
pp. 232-235 ◽  
Author(s):  
Andrew J. Martin ◽  
Christopher J. Hammond ◽  
H. Jane Dobbs ◽  
Safa Al-Sarraj ◽  
Nicholas W. M. Thomas
Keyword(s):  
Hodgkin Disease ◽  
Second Primary ◽  
Combined Modality Treatment ◽  
Spinal Meningioma ◽  
Primary Tumors ◽  
Content Type ◽  
Radiation Induced ◽  
Mutagenic Effects ◽  
Long Term Survivors

✓ Long-term survivors of Hodgkin disease may develop second primary tumors caused by the mutagenic effects of radio- and chemotherapy. The authors describe the case of a 35-year-old woman who presented with an unusual meningioma of the cervical spine 9 years after undergoing combined-modality treatment for Hodgkin disease. To the authors' knowledge, this is the first report of spinal meningioma as a complication of such therapy. Whereas radiation-induced intracranial meningiomas are well described in the literature, treatment-induced meningiomas of the spine have not been widely recognized.

scholarly journals A Low-g MEMS Accelerometer with High Sensitivity, Low Nonlinearity and Large Dynamic Range Based on Mode-Localization of 3-DoF Weakly Coupled Resonators

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 310
Author(s):  
Muhammad Mubasher Saleem ◽  
Shayaan Saghir ◽  
Syed Ali Raza Bukhari ◽  
Amir Hamza ◽  
Rana Iqtidar Shakoor ◽  
...  
Keyword(s):  
Microelectromechanical Systems ◽  
Dynamic Range ◽  
Proof Mass ◽  
Amplitude Ratio ◽  
Silicon On Insulator ◽  
Coupled Resonators ◽  
Mode Localization ◽  
Mems Accelerometer ◽  
Weakly Coupled ◽  
Input Acceleration

This paper presents a new design of microelectromechanical systems (MEMS) based low-g accelerometer utilizing mode-localization effect in the three degree-of-freedom (3-DoF) weakly coupled MEMS resonators. Two sets of the 3-DoF mechanically coupled resonators are used on either side of the single proof mass and difference in the amplitude ratio of two resonator sets is considered as an output metric for the input acceleration measurement. The proof mass is electrostatically coupled to the perturbation resonators and for the sensitivity and input dynamic range tuning of MEMS accelerometer, electrostatic electrodes are used with each resonator in two sets of 3-DoF coupled resonators. The MEMS accelerometer is designed considering the foundry process constraints of silicon-on-insulator multi-user MEMS processes (SOIMUMPs). The performance of the MEMS accelerometer is analyzed through finite-element-method (FEM) based simulations. The sensitivity of the MEMS accelerometer in terms of amplitude ratio difference is obtained as 10.61/g for an input acceleration range of ±2 g with thermomechanical noise based resolution of 0.22 and nonlinearity less than 0.5%.

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