The Temperature Dependent Damping Behavior of Novel Nanocomposites for Structural Materials Applications

2003 ◽  
Vol 791 ◽  
Author(s):  
Ramazan Asmatulu ◽  
Rick Claus ◽  
Jeff Mecham ◽  
Dan Inman
Keyword(s):  
Fine Particles ◽  
Mechanical Vibration ◽  
Broad Temperature Range ◽  
Test Results ◽  
Temperature Dependent ◽  
Temperature Range ◽  
Interfacial Sliding ◽  
Damping Behavior ◽  
Resonance Frequencies ◽  
Substrate Surfaces

ABSTRACTNear nanoscale fine particles including vanadium dioxide (VO2) and zinc oxide (ZnO) were incorporated into matrix materials (tin and polymer adhesives). A number of mechanical damping tests were conducted on the prepared composite materials at frequency ranges of 0 − 2 kHz and over a broad temperature range. The mechanical vibration test results showed that VO2 and ZnO gave significantly higher negative-stiffness (or damping) at approximately 68 °C (155 F) and 29 °C (85 F). For example, approximately 15% and 12% damping values were achieved at first and second resonance frequencies, respectively, which can potentially prevent vibration on the materials. This significant improvement on the damping of the nanocomposite material may be because of the ferroelasticity, viscoelasticity and/or interfacial sliding at those particular temperatures. It was also observed the etching of substrate surfaces improved adhesion and contributed consistent results to vibration testing reproducibility. Thus, it is concluded that nanocomposite existing damping properties can be an important method to achieve large damping responses over a broad temperature range.

scholarly journals Temperature Dependent Seed Germination of Dalbergia nigra Allem (Leguminosae)

2001 ◽  
Vol 44 (4) ◽  
pp. 401-404 ◽  
Author(s):  
Fernanda G. A. Ferraz-Grande ◽  
Massanori Takaki
Keyword(s):  
Seed Germination ◽  
Endangered Species ◽  
High Temperatures ◽  
Broad Temperature Range ◽  
Optimum Temperature ◽  
Temperature Dependent ◽  
Temperature Range ◽  
Dalbergia Nigra ◽  
The Mean ◽  
Kinetics Of

The germination of endangered species Dalbergia nigra was studied and 30.5° C was found as optimum temperature, although the species presented a broad temperature range where germination occurs and light had no effect. The analysis of kinetics of seed germination confirmed the asynchronized germination below and above the optimum temperature. The light insensitive seed and germination also at high temperatures indicated that D. nigra could occur both in understories and gaps where the mean temperature was high.

Plane Wave Resonance in the Tire Air Cavity as a Vehicle Interior Noise Source

1995 ◽  
Vol 23 (1) ◽  
pp. 2-10 ◽  
Author(s):  
J. K. Thompson
Keyword(s):  
Closed Form Solution ◽  
Form Solution ◽  
Interior Noise ◽  
Cavity Resonance ◽  
Test Results ◽  
Vehicle Interior ◽  
Air Cavity ◽  
Vehicle Interior Noise ◽  
Wave Resonance ◽  
Resonance Frequencies

Abstract Vehicle interior noise is the result of numerous sources of excitation. One source involving tire pavement interaction is the tire air cavity resonance and the forcing it provides to the vehicle spindle: This paper applies fundamental principles combined with experimental verification to describe the tire cavity resonance. A closed form solution is developed to predict the resonance frequencies from geometric data. Tire test results are used to examine the accuracy of predictions of undeflected and deflected tire resonances. Errors in predicted and actual frequencies are shown to be less than 2%. The nature of the forcing this resonance as it applies to the vehicle spindle is also examined.

A passively mode-locked quantum-dot laser operating over a broad temperature range

2012 ◽  
Vol 101 (7) ◽  
pp. 071112 ◽  
Author(s):  
J. K. Mee ◽  
M. T. Crowley ◽  
N. Patel ◽  
D. Murrell ◽  
R. Raghunathan ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Broad Temperature Range ◽  
Temperature Range ◽  
Quantum Dot Laser

scholarly journals Empirical Model With Excellent Statistical Properties for Describing Temperature-Dependent Developmental Rates of Insects and Mites

2017 ◽  
Vol 110 (3) ◽  
pp. 302-309 ◽  
Author(s):  
David A. Ratkowsky ◽  
Gadi V. P. Reddy
Keyword(s):  
Nonlinear Regression ◽  
Empirical Model ◽  
Minimum Variance ◽  
Statistical Properties ◽  
Parameter Estimates ◽  
Regression Equations ◽  
Temperature Dependent ◽  
Temperature Range ◽  
Least Squares Estimators ◽  
Development Rates

Abstract Previous empirical models for describing the temperature-dependent development rates for insects include the Briére, Lactin, Beta, and Ratkowsky models. Another nonlinear regression model, not previously considered in population entomology, is the Lobry–Rosso–Flandrois model, the shape of which is very close to that of the Ratkowsky model in the suboptimal temperature range, but which has the added advantage that all four of its parameters have biological meaning. A consequence of this is that initial parameter estimates, needed for solving the nonlinear regression equations, are very easy to obtain. In addition, the model has excellent statistical properties, with the estimators of the parameters being “close-to-linear,” which means that the least squares estimators are close to being unbiased, normally distributed, minimum variance estimators. The model describes the pooled development rates very well throughout the entire biokinetic temperature range and deserves to become the empirical model of general use in this area.

Effects of Macroscopic Pores on the Damping Behaviors of Metal Materials

2011 ◽  
Vol 66-68 ◽  
pp. 1155-1162
Author(s):  
Jian Ning Wei ◽  
Gen Mei Li ◽  
Li Ling Zhou ◽  
Xue Yun Zhou ◽  
Jian Min Yu ◽  
...  
Keyword(s):  
Internal Friction ◽  
Pure Aluminum ◽  
Air Pressure ◽  
Damping Capacity ◽  
Infiltration Process ◽  
Pressure Infiltration ◽  
Temperature Range ◽  
Commercially Pure ◽  
Damping Behavior ◽  
Metal Materials

A large number of macroscopic pores were introduced into commercially pure aluminum (Al) and Zn-Al eutectoid alloy by air pressure infiltration process to comparatively study the influence of macroscopic pores on the damping behaviors of the materials. Macroscopic pores size are on the order of a millimetre (0.5~1.4mm) and in large proportions, typically high 76vol.%. The damping behavior of the materials is characterized by internal friction (IF). The IF was measured on a multifunction internal friction apparatus (MFIFA) at frequencies of 0.5, 1.0 and 3.0 Hz over the temperature range of 25 to 400 °C, while continuously changing temperature. The damping capacity of the metal materials is shown to increase with introducing macroscopic pores. Finally, the operative damping mechanisms in the metal materials with macroscopic pores were discussed in light of IF measurements.

Analysis of temperature dependent electrical characteristics of Au/n-GaAs/GaAs structures in a wide temperature range

Vacuum ◽  
2008 ◽  
Vol 83 (2) ◽  
pp. 276-281 ◽  
Author(s):  
A. Bengi ◽  
S. Altındal ◽  
S. Özçelik ◽  
S.T. Agaliyeva ◽  
T.S. Mammadov
Keyword(s):  
Wide Temperature Range ◽  
Electrical Characteristics ◽  
Temperature Dependent ◽  
Temperature Range

Nanowires self-assemble into β-MnO2 nanospheres to form crosslinking 3D hierarchical porous networks: with template-free fabrication and good supercapacitive performance over a broad temperature range

2021 ◽  
Vol 5 (19) ◽  
pp. 4944-4954
Author(s):  
Li-Li Yu ◽  
Wei-Ling Xu ◽  
Jian-Guo Zhang ◽  
Shuang Li ◽  
Rong-Bing Li ◽  
...  
Keyword(s):  
Broad Temperature Range ◽  
Supercapacitive Performance ◽  
Temperature Range ◽  
Porous Networks ◽  
Self Assembling ◽  
Hierarchical Porous ◽  
Template Free

Template-free fabrication of nanowires self-assembling into nanospheres and crosslinking into 3D hierarchical porous β-MnO2 networks with good supercapacitive performance over a broad temperature range.

scholarly journals Experimental and computational kinetics investigations for the reactions of Cl atoms with series of unsaturated ketones in gas phase

2017 ◽  
Author(s):  
Siripina Vijayakumar ◽  
Avinash Kumar ◽  
Balla Rajakuma
Keyword(s):  
Gas Phase ◽  
State Theory ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Temperature Dependent ◽  
Unsaturated Ketones ◽  
Temperature Range ◽  
Computational Calculations ◽  
Temperature Rate ◽  
Cl Atoms

Abstract. Temperature dependent rate coefficients for the gas phase reactions of Cl atoms with 4-hexen-3-one and 5-hexen-2-one were measured over the temperature range of 298–363 K relative to 1-pentene, 1,3-butadiene and isoprene. Gas Chromatography (GC) was used to measure the concentrations of the organics. The derived temperature dependent Arrhenius expressions are k4-hexen-3-one+Cl (298–363 K) = (2.82 ± 1.76)×10−12exp [(1556 ± 438)/T] cm3 molecule−1 s−1 and k5-hexen-2-one+Cl (298–363 K) = (4.6 ± 2.4)×10−11exp[(646 ± 171)/T] cm3 molecule−1 s−1. The corresponding room temperature rate coefficients are (5.54 ± 0.41)×10−10 cm3 molecule−1 s−1 and (4.00 ± 0.37)×10−10 cm3 molecule−1 s−1 for the reactions of Cl atoms with 4-hexen-3-one and 5-hexen-2-one respectively. To understand the mechanism of Cl atom reactions with unsaturated ketones, computational calculations were performed for the reactions of Cl atoms with 4-hexen-3-one, 5-hexen-2-one and 3-penten-2-one over the temperature range of 275–400 K using Canonical Variational Transition state theory (CVT) with Small Curvature Tunneling (SCT) in combination with CCSD(T)/6-31+G(d, p)//MP2/6-311++G(d, p) level of theory. Atmospheric implications, reaction mechanism and feasibility of the title reactions are discussed in this manuscript.

Thermodynamics of Sr2NiMoO6 and Sr2CoMoO6 and their stability under reducing conditions

2018 ◽  
Vol 20 (30) ◽  
pp. 20108-20116 ◽  
Author(s):  
V. V. Sereda ◽  
D. S. Tsvetkov ◽  
A. L. Sednev ◽  
A. I. Druzhinina ◽  
D. A. Malyshkin ◽  
...  
Keyword(s):  
Thermodynamic Functions ◽  
Broad Temperature Range ◽  
Temperature Range ◽  
Reducing Conditions

Essential thermodynamic functions, obtained for Sr2NiMoO6 and Sr2CoMoO6 in broad temperature range, allowed to evaluate their stability in reducing conditions.

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