scholarly journals Repair of Stiction Failed MEMS Using Structural Vibrations

2007 ◽  
Author(s):  
Drew Goettler ◽  
Amit Savkar ◽  
Kevin Murphy ◽  
Zayd Chad Leseman
Keyword(s):  
Damping Ratio ◽  
Laser Doppler Vibrometer ◽  
Physical Parameters ◽  
Cantilever Beams ◽  
Bending Rigidity ◽  
Structural Vibrations ◽  
Viable Approach ◽  
Set Up ◽  
The Stability

It has been shown in recent times that the use of structural vibrations is a viable approach in repairing stiction failed MEMS cantilever beams. It has also been observed that such a technique is sensitive to various parametric values associated with the de-sticking of these beams. In the current paper we present experimental results which characterize the ideal cantilever beam. An analytical model of stiction failed MEMS cantilever beams under electrostatic actuation is presented. Physical parameters such as stiffness, bending rigidity, damping, excitation voltage, etc. are incorporated in terms of Mathieu parameters to study the stability of the system. An experimental characterization of natural frequency, Young’s Modulus, and damping ratio, which form important components of the analysis, is presented. Accompanying these results is a description of the experimental set up used for finding these parameters. Experiments were performed at both atmospheric and vacuum pressures. An interferometric microscope mounted above the glass window of the vacuum chamber was used to determine the crack length of each beam and observe the profiles of the arrays of microcantilevers in-situ. A Laser Doppler Vibrometer was used for determination of characterization parameters. The microcantilevers were fabricated using the SUMMiT IV process of Sandia National Laboratories. Structural vibrations were induced by placing an alternating voltage on a cofabricated actuation pad located under the microcantilevers near their anchor point. Theoretical modeling shows the dependence of physical parameters that lead to stiction repair.

scholarly journals Charge Transfer Complexes of Ketotifen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8-Tetracyanoquodimethane: Spectroscopic Characterization Studies

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2039
Author(s):  
Gamal A. E. Mostafa ◽  
Ahmed Bakheit ◽  
Najla AlMasoud ◽  
Haitham AlRabiah
Keyword(s):  
Charge Transfer ◽  
Spectroscopic Characterization ◽  
Molar Ratio ◽  
Charge Transfer Complexes ◽  
Physical Parameters ◽  
Spectrophotometric Methods ◽  
Theoretical Approaches ◽  
The Stability ◽  
Ct Complexes

The reactions of ketotifen fumarate (KT) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π acceptors to form charge transfer (CT) complexes were evaluated in this study. Experimental and theoretical approaches, including density function theory (DFT), were used to obtain the comprehensive, reliable, and accurate structure elucidation of the developed CT complexes. The CT complexes (KT-DDQ and KT-TCNQ) were monitored at 485 and 843 nm, respectively, and the calibration curve ranged from 10 to 100 ppm for KT-DDQ and 2.5 to 40 ppm for KT-TCNQ. The spectrophotometric methods were validated for the determination of KT, and the stability of the CT complexes was assessed by studying the corresponding spectroscopic physical parameters. The molar ratio of KT:DDQ and KT:TCNQ was estimated at 1:1 using Job’s method, which was compatible with the results obtained using the Benesi–Hildebrand equation. Using these complexes, the quantitative determination of KT in its dosage form was successful.

scholarly journals A Study of the Stability of a Plate-Like Load Towed beneath a Helicopter

1971 ◽  
Vol 13 (5) ◽  
pp. 330-343 ◽  
Author(s):  
D. F. Sheldon
Keyword(s):  
Equations Of Motion ◽  
Physical Parameters ◽  
Recent Experience ◽  
Wind Tunnel Testing ◽  
Stability Derivatives ◽  
Direct Indication ◽  
Metric Dimensions ◽  
Set Up ◽  
The Stability ◽  
Derivative Information

Recent experience has shown that a plate-like load suspended beneath a helicopter moving in horizontal forward flight has unstable characteristics at both low and high forward speeds. These findings have prompted a theoretical analysis to determine the longitudinal and lateral dynamic stability of a suspended pallet. Only the longitudinal stability is considered here. Although it is strictly a non-linear problem, the usual assumptions have been made to obtain linearized equations of motion. The aerodynamic derivative data required for these equations have been obtained, where possible, for the appropriate ranges of Reynolds and Strouhal number by means of static and dynamic wind tunnel testing. The resulting stability equations (with full aerodynamic derivative information) have been set up and solved, on a digital computer, to give direct indication of a stable or unstable system for a combination of physical parameters. These results have indicated a longitudinal unstable mode for all practical forward speeds. Simultaneously the important stability derivatives were found for this instability and modifications were made subsequently in the suspension system to eliminate the instabilities in the longitudinal sense. Throughout this paper, all metric dimensions are given approximately.

Influences of experimental parameters on the stability of a benzoporphyrin drug in water/ethanol mixtures: a statistical approach investigation

2005 ◽  
Vol 09 (09) ◽  
pp. 609-616 ◽  
Author(s):  
André Luiz Tessaro ◽  
Daniela Martins Fernandes ◽  
Ailton José Terezo ◽  
Vagner Roberto de Souza ◽  
Noboru Hioka
Keyword(s):  
Water Content ◽  
Aqueous Media ◽  
Solvent Mixtures ◽  
Wide Range ◽  
Experimental Parameters ◽  
Carboxylic Groups ◽  
Minimum Number ◽  
Set Up ◽  
The Stability

The benzoporphyrin derivative, named B3B, is a promising new drug for application in photodynamic therapy. In aqueous organic solvent mixtures, B3B, can be used in topical application for superficial diseases, like for skin cancer. In this paper, the self-aggregation phenomena of porphyrin molecules in aqueous media was investigated using a chemometric tool to evaluate the effects of experimental variables on the stability of the B3B monomer in water/ethanol mixtures. A 23 factorial design was employed which permitted determination of the magnitude of experimental parameters which influence aggregation of the drug at different pHs using the minimum number of experiments. At first, the pK a values of the B3B in water/ethanol mixtures were determined by spectrophotometric measurements, resulting in pK a1 = 3.3 and pK a2 = 5.7, corresponding to the imino nitrogens and carboxylic groups, respectively. The experimental variables (B3B concentration, time and water/ethanol composition) were evaluated in three protonation states of the drug, at pH 7.0, 4.1 and 2.6. The two levels (low and high) were set up at: time 5 (-) and 360 minutes (+); [B3B] 4.4 × 10-6(-) and 26.5 × 10-6 M (+); and water content in ethanol 40 (-) and 60% (+). The main parameter that determines the magnitude of the effects seems to be the charge component of B3B, which can be modulated by the pH. The results from the 23 fractional design indicated that the main variable inducing B3B aggregation is the water percentage in ethanol at each pH selected. The magnitude of this effect was pronounced at pH 4.1 where the carboxylic and nitrogen free base forms of B3B are maintained. The factors of time and [B3B], despite being small, are not insignificant. Finally, the effect of water content was investigated in a wide range of water percentage in these three pHs.

scholarly journals Selection of Best Fit Correlation for Compression Index of Soil from District Bannu

2019 ◽  
Vol 38 (1) ◽  
pp. 221-226
Author(s):  
Zia-ur- Rahman ◽  
Siraj - uddin ◽  
Aizaz Ahmad Khan ◽  
Mati ullah
Keyword(s):  
Moisture Content ◽  
Soil Parameters ◽  
Compression Index ◽  
Undisturbed Soil ◽  
Consolidation Test ◽  
Set Up ◽  
The Stability ◽  
Best Fit ◽  
Selection Of

Geotechnical investigation is one of the major steps in the safe and economic design of foundation for any structure. This requires some soil parameters to be established. CI (Compression Index) is one of these parameters. The stability of a foundation is not fully justified as long as the magnitude of settlement is unknown. The problem arises when the value of CI is needed badly and a consolidation test is set up for this purpose which consumes almost 3 days for its completion provided that the assembly would not be disturbed. Little amount of disturbance can cause serious error in further calculations and plotting of data. Undisturbed soil sample is the primary demand of consolidation test which is a tough job for a person having not been experienced very much in the fieldwork. In order to overcome these complexities, the researchers have established various correlations between compression index and some basic soil properties like Atterberg limits, void ratio, natural moisture content and OMC (Open Moisture Content), as they are simple to be determined and takes small amount of time. This research has been conducted on soil samples collected from a single spot at an interval of 5ft depth for the sake of validation of a suitable correlation for Bannu District, KPK (Khyber Pakhtunkhwa), Pakistan so that the determination of compression index becomes simple and convenient.

On the Mechanism of Fluidelastic Instability of a Tube Placed in an Array Subjected to Two-Phase Crossflow

1995 ◽  
Vol 117 (4) ◽  
pp. 706-712 ◽  
Author(s):  
Y. Joo ◽  
V. K. Dhir
Keyword(s):  
Void Fraction ◽  
Damping Ratio ◽  
Test Tube ◽  
Spring Constant ◽  
Cantilever Beams ◽  
Two Phase ◽  
Fluidelastic Instability ◽  
Drag And Lift ◽  
Effective Spring Constant

In this work, the fluidelastic instability of a tube placed in an array subjected to two-phase crossflow has been studied. For the determination of fluidelastic instability, acrylic tubes 2.2 cm or 2.37 cm in diameter and 20 cm in length were arranged in a triangular array with pitch to diameter ratio of 1.4 and 1.3. The test tube was flexibly supported with two cantilever beams. By installing cantilever beams horizontally and vertically, drag and lift direction tube vibration were studied. The total damping ratio is found to increase as the liquid gap velocity or void fraction increases. It has been found that the effective spring constant decreases rapidly with increase of liquid gap velocity or void fraction just prior to the onset of instability. For the range of parameters studied in this work, the onset of fluidelastic instability is associated with a rapid decrease of the effective spring constant because for a given applied force the amplitude of the tube vibration is inversely proportional to the spring constant.

Respirometry for determination of the influents SS-concentration

1996 ◽  
Vol 33 (1) ◽  
pp. 311-323 ◽  
Author(s):  
A. Witteborg ◽  
A. van der Last ◽  
R. Hamming ◽  
I. Hemmers
Keyword(s):  
Experimental Design ◽  
Activated Sludge ◽  
Substrate Concentration ◽  
Full Scale ◽  
Activated Sludge Process ◽  
Respiration Rates ◽  
On Line ◽  
Large Measurement ◽  
Set Up

A method is presented for determining influent readily biodegradable substrate concentration (SS). The method is based on three different respiration rates, which can be measured with a continuous respiration meter which is operated in a cyclic way. Within the respiration meter nitrification is inhibited through the addition of ATU. Simulations were used to develop the respirometry set-up and decide upon the experimental design. The method was tested as part of a large measurement programme executed at a full-scale plant. The proposed respirometry set-up has been shown to be suitable for a semi-on-line determination of an influent SS which is fully based on the IAWQ #1 vision of the activated sludge process. The YH and the KS play a major role in the principle, and should be measured directly from the process.

Determining the Norton’s Equivalent Model of Distribution System with Distributed Generation (DG) for Stability Analysis

2019 ◽  
Vol 12 (2) ◽  
pp. 190-198
Author(s):  
Sunny Katyara ◽  
Lukasz Staszewski ◽  
Faheem Akhtar Chachar
Keyword(s):  
Distributed Generation ◽  
Normal Condition ◽  
Distribution System ◽  
Distribution Networks ◽  
Equivalent Model ◽  
Stability Factor ◽  
Matlab Simulation ◽  
The Stability ◽  
Stability Issues

Background: Since the distribution networks are passive until Distributed Generation (DG) is not being installed into them, the stability issues occur in the distribution system after the integration of DG. Methods: In order to assure the simplicity during the calculations, many approximations have been proposed for finding the system’s parameters i.e. Voltage, active and reactive powers and load angle, more efficiently and accurately. This research presents an algorithm for finding the Norton’s equivalent model of distribution system with DG, considering from receiving end. Norton’s model of distribution system can be determined either from its complete configuration or through an algorithm using system’s voltage and current profiles. The algorithm involves the determination of derivative of apparent power against the current (dS/dIL) of the system. Results: This work also verifies the accuracy of proposed algorithm according to the relative variations in the phase angle of system’s impedance. This research also considers the varying states of distribution system due to switching in and out of DG and therefore Norton’s model needs to be updated accordingly. Conclusion: The efficacy of the proposed algorithm is verified through MATLAB simulation results under two scenarios, (i) normal condition and (ii) faulty condition. During normal condition, the stability factor near to 1 and change in dS/dIL was near to 0 while during fault condition, the stability factor was higher than 1 and the value of dS/dIL was away from 0.

Synthesis and solvatochromic studies of 2- amino-3-phenolazo1-(4-sulfophenyl)-3-methyi-5-pyrozolone and use it for the determination of trace amount of Nickel (II) in blood samples

2016 ◽  
Vol 5 (10) ◽  
pp. 4920
Author(s):  
Amar M. Ali ◽  
Hussain. J. Mohammed*
Keyword(s):  
Stability Constant ◽  
Trace Amount ◽  
Benzenesulfonic Acid ◽  
Determination Method ◽  
Blood Samples ◽  
Determination Of Nickel ◽  
Normal Human ◽  
The Stability ◽  
Normal Human Blood

A new, simple, sensitive and rapid spectrophotometric method is proposed for the determination of trace amount of Nickel (II). The method is based on the formation of a 1:2 complex with 4-(4-((2-hydroxy-6-nitrophenyl) diazenyl) -3-methyl-5-oxo-2, 5-dihydro-1H-pyrazol-1-yl) benzenesulfonic acid (2-ANASP) as a new reagent is developed. The complex has a maximum absorption at 516 nm and εmax of 1. 84 X 105 L. mol-1. cm-1. A linear correlation (0. 25 – 4. 0μg. ml-1) was found between absorbance at λmax and concentration. The accuracy and reproducibility of the determination method for various known amounts of Nickel (II) were tested. The results obtained are both precise (RSD was 1. 2 %) and accurate (relative error was 0. 787 %). The effect of diverse ions on the determination of Nickel (II) to investigate the selectivity of the method were also studied. The stability constant of the product was 0. 399 X 106 L. mol-1. The proposed method was successfully applied to the analysis of diabetes blood and normal human blood. 

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