Accurate evaluation of the real and imaginary material constants for a piezoelectric resonator in the radial mode

1991 ◽  
Vol 119 (1) ◽  
pp. 17-32 ◽  
Author(s):  
S. Sherrit ◽  
N. Gauthier ◽  
H. D. Wiederick ◽  
B. K. Mukherjee
Keyword(s):  
Radial Mode ◽  
Piezoelectric Resonator ◽  
Accurate Evaluation ◽  
The Real ◽  
Material Constants

scholarly journals Shy Times in 1850s Wellington: will the real architects please stand up?

2021 ◽  
Vol 9 ◽  
pp. 21-28
Author(s):  
Adrian Humphris ◽  
Geoff Mew
Keyword(s):  
Capital City ◽  
Accurate Evaluation ◽  
The Real ◽  
Alternative Employment ◽  
Local Newspapers ◽  
The People ◽  
Minimal Work ◽  
Building Designs ◽  
Multiple Skills ◽  
Better Than

Wellington was in a period of transition in the 1850s. The first flurry of settlement was easing somewhat and trading was becoming established. However, the earthquakes of 1848 and 1855 shook not only buildings not designed to withstand them, but also the confidence of the immigrant population. People were quick to realise that timber flexed better than brick or cob, but, in the process, they lost several of the earliest buildings with any pretensions to architectural merit. Together with the shaky nature of the economy, and the fact that Auckland was the capital city, there was little incentive for men whose sole training was in architecture to attempt to practice full time.The paucity of architectural records from the 1850s further complicates accurate evaluation of the situation, but it is clear that many of the people designing buildings had multiple skills in several other fields besides architecture. Buildings definitely dated to the 1850s that remain in Wellington can be numbered on one hand and not one of them can be said to have been designed by an architect. The two men with the largest tallies of Wellington building designs in the 1850s also claimed skills in surveying and civil engineering, whereas the two (possibly three) trained architects that we know of seem to have obtained minimal work in their field and to have largely diversified into other occupations. A further five names are associated with Wellington architecture in some way during the 1850s, either with the design of single buildings or simply advertising their services in local newspapers - with no evidence they actually obtained any work. In this paper we look at the backgrounds of the major designers including the trained architects, their work and a few of the factors which caused most of them to seek alternative employment.

scholarly journals Evaluation of Elastic Properties and Conductivity of Chitosan Acetate Films in Ammonia and Water Vapors Using Acoustic Resonators

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2236 ◽  
Author(s):  
Boris D. Zaitsev ◽  
Andrey A. Teplykh ◽  
Fedor S. Fedorov ◽  
Artem K. Grebenko ◽  
Albert G. Nasibulin ◽  
...  
Keyword(s):  
Electric Field ◽  
Resonance Frequency ◽  
Chitosan Film ◽  
Piezoelectric Resonator ◽  
The Real ◽  
Lateral Electric Field ◽  
Maximum Value ◽  
Water Vapors ◽  
Resonance Properties ◽  
Parallel Resonance

Novel bio-materials, like chitosan and its derivatives, appeal to finding a new niche in room temperature gas sensors, demonstrating not only a chemoresistive response, but also changes in mechanical impedance due to vapor adsorption. We determined the coefficients of elasticity and viscosity of chitosan acetate films in air, ammonia, and water vapors by acoustic spectroscopy. The measurements were carried out while using a resonator with a longitudinal electric field at the different concentrations of ammonia (100–1600 ppm) and air humidity (20–60%). It was established that, in the presence of ammonia, the longitudinal and shear elastic modules significantly decreased, whereas, in water vapor, they changed slightly. At that, the viscosity of the films increased greatly upon exposure to both vapors. We found that the film’s conductivity increased by two and one orders of magnitude, respectively, in ammonia and water vapors. The effect of analyzed vapors on the resonance properties of a piezoelectric resonator with a lateral electric field that was loaded by a chitosan film on its free side was also experimentally studied. In these vapors, the parallel resonance frequency and maximum value of the real part of the electrical impedance decreased, especially in ammonia. The results of a theoretical analysis of the resonance properties of such a sensor in the presence of vapors turned out to be in a good agreement with the experimental data. It has been also found that with a growth in the concentration of the studied vapors, a decrease in the elastic constants, and an increase in the viscosity factor and conductivity lead to reducing the parallel resonance frequency and the maximum value of the real part of the electric impedance of the piezoelectric resonator with a lateral electric field that was loaded with a chitosan film. This leads to an increase in the sensitivity of such a sensor during exposure to these gas vapors.

Guided Wave Propagation in Tubular Section With Multi-Layered Viscoelastic Coating: Part I — Axial Waves

2013 ◽  
Author(s):  
Chi-Wei Kuo ◽  
C. Steve Suh
Keyword(s):  
Phase Velocity ◽  
Wave Attenuation ◽  
Wave Dispersion ◽  
Guided Wave ◽  
Longitudinal Waves ◽  
The Real ◽  
Material Constants ◽  
Coating Layers ◽  
The Impact ◽  
Viscoelastic Coatings

Propagating waves physically admissible in a tubular section are derived to establish their dispersion characteristics in response to the presence of multi-layered viscoelastic coatings. Longitudinal waves that propagate in the axial direction are studied. To characterize the hollow cylinder with coating layers, wave dispersion and attenuation are studied using the “global matrix” technique. Since each layer is considered to be perfectly bonded to each other, displacement and strain continuity are imposed as the interfacial boundary conditions. Viscoelastic coating materials such as bitumen and epoxy serve to improve pipeline reliability, but they also dampen and dissipate wave energy. The viscoelastic materials are studied as well. By replacing the real material constants with complex material constants in the characteristic equation, the impact of the viscoelastic coatings on wave dispersion is established. Bisection method is followed to find the real and complex roots of the three characteristic equations derived. Roots thus obtained are manipulated to allow the phase velocity and attenuation dispersion to be plotted against frequency. The dispersion of phase velocity and wave attenuation for coated pipes are evaluated against a baseline model which is the bare, uncoated tubing to establish the propagation characteristics of the guided shear and longitudinal waves in the presence of multiple coating layers. The effects of increasing attenuation parameter and coating thickness are also investigated.

scholarly journals The Rise and Fall of Rosiglitazone

2009 ◽  
Vol 1 ◽  
pp. CMT.S2368
Author(s):  
P. Tatti
Keyword(s):  
Side Effects ◽  
Regulatory Authority ◽  
Cardiovascular Safety ◽  
Accurate Evaluation ◽  
The Real ◽  
Real Existence ◽  
Potential Risks ◽  
Early Warnings

Rosiglitazone is a member of the Thiazolidinedione class of drugs with a potent insulin sensitizing action. The drug has been extensively used and many early warnings on its potential risks were ignored mostly due to an aggressive commercial strategy. In 2007 some papers raised doubts on the cardiovascular safety of the drug and started a serious dispute. Irrespective of the real existence of this risk the story of Rosiglitazone led to the unveiling of many other side effects and emphasizes the need for a more accurate evaluation of any drug before is approved by the regulatory authority.

Guided Wave Propagation in Tubular Section With Multi-Layered Viscoelastic Coating: Part II — Circumferential Waves

2013 ◽  
Author(s):  
Chi-Wei Kuo ◽  
C. Steve Suh
Keyword(s):  
Phase Velocity ◽  
Wave Attenuation ◽  
Wave Dispersion ◽  
Guided Wave ◽  
Longitudinal Waves ◽  
The Real ◽  
Material Constants ◽  
Coating Layers ◽  
The Impact ◽  
Viscoelastic Coatings

Propagating waves physically admissible in a tubular section are derived to establish their dispersion characteristics in response to the presence of multi-layered viscoelastic coatings. Shear and longitudinal waves along the circumferential direction were investigated. To characterize the hollow cylinder with coating layers, wave dispersion and attenuation are studied using the “global matrix” technique. Since each layer is considered to be perfectly bonded to each other, displacement and strain continuity are imposed as the interfacial boundary conditions. Viscoelastic coating materials such as bitumen and epoxy serve to improve pipeline reliability, but they also dampen and dissipate wave energy. The viscoelastic materials are studied as well. By replacing the real material constants with complex material constants in the characteristic equation, the impact of the viscoelastic coatings on wave dispersion is established. Bisection method is followed to find the real and complex roots of the three characteristic equations derived. Roots thus obtained are manipulated to allow the phase velocity and attenuation dispersion to be plotted against frequency. The dispersion of phase velocity and wave attenuation for coated pipes are evaluated against a baseline model which is the bare, uncoated tubing to establish the propagation characteristics of the guided shear and longitudinal waves in the presence of multiple coating layers.

Scanning electron microscopy of human iliac bone by a simple preparation method

1990 ◽  
Vol 48 (3) ◽  
pp. 226-227
Author(s):  
Toshihiko Takita ◽  
Tomonori Naguro ◽  
Toshio Kameie ◽  
Akihiro Iino ◽  
Kichizo Yamamoto
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Real Surface ◽  
Public Attention ◽  
Preparation Methods ◽  
The Real ◽  
Simple Preparation ◽  
Scanning Electron

Recently with the increase in advanced age population, the osteoporosis becomes the object of public attention in the field of orthopedics. The surface topography of the bone by scanning electron microscopy (SEM) is one of the most useful means to study the bone metabolism, that is considered to make clear the mechanism of the osteoporosis. Until today many specimen preparation methods for SEM have been reported. They are roughly classified into two; the anorganic preparation and the simple preparation. The former is suitable for observing mineralization, but has the demerit that the real surface of the bone can not be observed and, moreover, the samples prepared by this method are extremely fragile especially in the case of osteoporosis. On the other hand, the latter has the merit that the real information of the bone surface can be obtained, though it is difficult to recognize the functional situation of the bone.

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