scholarly journals New Capacitive Thermal Age Tag for Predicting Remaining Thermal Life of Multiple Products

2020 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Kenneth Watkins ◽  
Stephanie Steelman
Keyword(s):  
Activation Energy ◽  
Thermal Aging ◽  
Thermal Environment ◽  
Data Logging ◽  
Multiple Products ◽  
Passive Tags ◽  
Wide Range ◽  
Degradation Activation Energy ◽  
Thermal Life ◽  
Product Degradation

This paper proposes use of a new capacitive thermal age sensor that inherently integrates time and temperature without batteries or electronic memory to predict the remaining thermal life of a wide range of monitored products. The sensor is a tiny capacitor comprising a polymeric dielectric between two conductive plates. Capacitance of the sensor increases during thermal aging due to shrinkage of the polymer. Additives such as catalysts adjust the activation energy (Ea) of capacitance change with thermal age.A thermal age tag, incorporating two capacitive sensors of different activation energy, can be used to determine the effective temperature (Teff) of a complex thermal environment at wide range of product degradation activation energies. Correlation of the thermal age of the tag at the monitored product’s degradation activation energy to product thermal aging data provides estimated remaining thermal life of the product. The thermal age tag requires no batteries or electronic memory required in data-logging approaches resulting in reduced size, weight and cost. These passive tags are potentially maintenance free for the life of the product.This paper describes the development of a universal thermal age (UTA) tag incorporating capacitive thermal age sensors and preliminary co-aging trials with a variety of selected polymeric products to demonstrate feasibility of this approach.

scholarly journals Use of Passive Age Sensors for Projecting Remaining Thermal Life of Materials

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Kenneth Watkins
Keyword(s):  
Thermal Environment ◽  
Electrical Power ◽  
Remaining Useful Life ◽  
Change Resistance ◽  
Internal Source ◽  
Sensor Resistance ◽  
Correlation Models ◽  
Wide Range ◽  
The Matrix ◽  
Thermal Life

This paper proposes use of passive thermal age sensors and empirical correlation models to project remaining useful life of thermally degradable products and materials. Thermal age sensors, comprising a selected polymeric matrix and conductive fillers, change resistance as the matrix thermally degrades in the same thermal environment as the monitored product or material. Thermal age sensor resistance represents the integrated time-temperature condition of the sensor at its characteristic activation energy. Empirical models correlate sensor resistance to a selected property of the material utilizing multi-temperature thermal aging data of the monitored material. These correlation models project the current condition of the selected product property, or, if end-of-life properties are specified, these models project the percentage of remaining design life of the material. Several applications of this approach are discussed utilizing thermal age sensors attached to monitored materials. An approach utilizing two thermal age sensors is introduced that allows a single tag to predict selected properties of many different materials. PHM tags utilizing passive thermal age sensors do not require an internal source of electrical power or internal memory, eliminating the need for batteries and significantly reducing data management issues. This approach can be expanded to a wide range of products and materials when sufficient thermal age data is available.

Hydrogenation of methylacetylene. III. The reaction of methylacetylene with hydrogen catalyzed by nickel, copper, and their alloys

1968 ◽  
Vol 46 (4) ◽  
pp. 623-633 ◽  
Author(s):  
R. S. Mann ◽  
K. C. Khulbe
Keyword(s):  
Activation Energy ◽  
Nickel Catalyst ◽  
Hydrogen Pressure ◽  
Constant Volume ◽  
Temperature Dependent ◽  
Nickel Copper ◽  
Wide Range ◽  
Initial Hydrogen Pressure

The reaction between methylacetylene and hydrogen over unsupported nickel, copper, and their alloys has been investigated in a static constant volume system between 20 and 220 °C for a wide range of reactant ratios. The order of reaction with respect to hydrogen was one and nearly independent of temperature. While the order of reaction with respect to methylacetylene over nickel catalyst was slightly negative and temperature dependent, it was always positive and nearly independent of temperature for copper and copper-rich alloys. Selectivity was independent of initial hydrogen pressure for nickel and copper only; for others it decreased rapidly with increasing hydrogen pressure. The overall activation energy varied between 9 and 21.2 kcal/g mole. Selectivity and extent of polymerization increased with increasing amount of copper in the alloy.

scholarly journals Temperature as a modulator of sexual selection

2018 ◽  
Author(s):  
Roberto García-Roa ◽  
Francisco Garcia-Gonzalez ◽  
Daniel W.A. Noble ◽  
Pau Carazo
Keyword(s):  
Global Warming ◽  
Sexual Selection ◽  
Thermal Environment ◽  
Abiotic Factors ◽  
Meta Analysis ◽  
Population Viability ◽  
Order Effects ◽  
Secondary Sexual Traits ◽  
Trade Offs ◽  
Wide Range

A central question in ecology and evolution is to understand why sexual selection varies so much in strength across taxa, and it has long been known that ecological factors are crucial to this respect. Temperature is a particularly critical abiotic ecological factor that can drastically modulate a wide range of physiological, morphological and behavioural traits, impacting individuals and populations at a global taxonomic scale. Furthermore, temperature exhibits substantial temporal variation (e.g. daily, seasonally and inter-seasonally), and hence for most species in the wild sexual selection will regularly unfold in a dynamic thermal environment. Unfortunately, studies have so far almost completely neglected the role of temperature as a modulator of sexual selection. Here, we outline the main pathways via which temperature can affect the intensity and form (i.e. mechanisms) of sexual selection, via: a) direct effects on secondary sexual traits and preferences (i.e. trait variance, opportunity for selection and trait-fitness covariance), and b) indirect effects on key mating parameters, sex-specific reproductive costs/benefits, trade-offs, demography and correlated abiotic factors. Building upon this framework, we show that, by focusing exclusively on the first order effects that environmental temperature has on traits linked with individual fitness and population viability, current global warming studies may be ignoring important eco-evolutionary feedbacks mediated by sexual selection. Finally, we tested the general prediction that temperature modulates sexual selection by conducting a meta-analysis of available studies experimentally manipulating temperature and reporting effects on the variance of male/female reproductive success and/or traits under sexual selection. Our results show a clear association between temperature and sexual selection measures in both sexes. In short, we suggest that studying the feedback between temperature and sexual selection processes can be vital to better understand variation in the strength of sexual selection in nature, and its consequences for population viability in response to environmental change (e.g. global warming).

Smart Temperature Sensors

2019 ◽  
pp. 223-250
Author(s):  
Ashraf A. Zaher
Keyword(s):  
Weather Forecast ◽  
Temperature Sensors ◽  
Consumer Electronics ◽  
Data Logging ◽  
Industrial Processing ◽  
Wide Range ◽  
Scada Systems ◽  
New Generation ◽  
And Control ◽  
Measurement And Control

Many real-world applications depend on temperature sensing and/or control. This includes a wide range of industrial processes, chemical reactors, and SCADA systems, in addition to other physical, mechanical, and biological systems. With the advancement of technology, it became possible to produce a new generation of smart and compact temperature sensors, which are capable of providing digital outputs that are more accurate, robust, and easily interfaced and integrated into measurement and control systems. This chapter first surveys traditional analog temperature sensors, such as RTDs and thermocouples, to provide a strong motivation for the need to adopt better and smarter techniques that mainly rely on digital technology (e.g., CMOS designs). Different interfacing techniques that do not need ADCs are introduced, including the programmable Arduino microcontrollers. Different applications will be explored that include automotive accessories, weather forecast, healthcare, industrial processing, firefighting, and consumer electronics. Both wired and wireless technologies, including the IoT, will be investigated as means for transmitting the sensed data for further processing and data logging. A special case study to provide information redundancy in industrial SCADA systems will be analyzed to illustrate the advantages and limitations of smart temperature sensors. The chapter concludes with a summary of the design effort, accuracy, performance, and cost effectiveness of smart temperature sensors while highlighting future trends in this field for different applications.

scholarly journals Interaction between Sound and Thermal Influences on Patient Comfort in the Hospitals of China’s Northern Heating Region

2019 ◽  
Vol 9 (24) ◽  
pp. 5551 ◽  
Author(s):  
Yue Wu ◽  
Qi Meng ◽  
Lei Li ◽  
Jingyi Mu
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Field Measurements ◽  
Negative Stimulus ◽  
Patient Comfort ◽  
Thermal Stimulus ◽  
Acoustic Environment ◽  
Heating Region ◽  
Increased Risk ◽  
Wide Range

Previous studies have found that hospitals are often inadequately ventilated in the heating region of China, which causes an increased risk of negative impacts on patients. The complex interaction between thermal comfort and acoustics presents considerable challenges for designers. There is a wide range of literature covering the area of the interaction between the sound–thermal, sound–odor, and acoustic–visual influences, but a focused research on the sound –thermal influence on comfort in hospitals has not been published yet. This paper describes a series of field measurements and subjective evaluations that investigate the thermal comfort and acoustic performance of eighteen hospitals in China. The results showed that the thermal comfort in the monitored wards was mostly acceptable, but the temperatures tended to be much higher and the humidity much lower, in practice than they were designed to be in the heating season. The most significant conclusion is that a positive thermal stimulus can create a comfortable thermal environment, which can improve patients’ evaluation of the acoustics, while a negative stimulus has the opposite effect. A comfortable acoustic environment also caused patients to positively evaluate thermal comfort. Moreover, the relationship between thermal and sound effects in the overall evaluation showed that they are almost equal.

Fuzzy logic approach for investigation of microstructure and mechanical properties of Sn96.5-Ag3.0-Cu0.5 lead free solder alloy

2017 ◽  
Vol 29 (4) ◽  
pp. 191-198 ◽  
Author(s):  
Muhammad Aamir ◽  
Izhar Izhar ◽  
Muhammad Waqas ◽  
Muhammad Iqbal ◽  
Muhammad Imran Hanif ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fuzzy Logic ◽  
Solder Alloy ◽  
Thermal Aging ◽  
Fuzzy Rule ◽  
Rule Base ◽  
Content Type ◽  
Wide Range ◽  
Fuzzy Logic Approach ◽  
Free Solder

Purpose This paper aims to develop a fuzzy logic-based algorithm to predict the intermetallic compound (IMC) size and mechanical properties of soldering material, Sn96.5-Ag3.0-Cu0.5 (SAC305) alloy, at different levels of temperature. The reliability of solder joint in materials selection is critical in terms of temperature, mechanical properties and environmental aspects. Owing to a wide range of soldering materials available, the selection space finds a fuzzy characteristic. Design/methodology/approach The developed algorithm takes thermal aging temperature for SAC305 alloy as input and converts it into fuzzy domain. These fuzzified values are then subjected to a fuzzy rule base, where a set of rules determines the IMC size and mechanical properties, such as yield strength (YS) and ultimate tensile strength (UTS) of SAC305 alloy. The algorithm is successfully simulated for various input thermal aging temperatures. To analyze and validate the developed algorithm, an SAC305 lead (Pb)-free solder alloy is developed and thermally aged at 40, 60 and 100°C temperature. Findings The experimental results indicate an average IMCs size of 5.967 (in Pixels), 19.850 N/mm2 YS and 22.740 N/mm2 UTS for SAC305 alloy when thermally aged at an elevated temperature of 140°C. In comparison, the simulation results predicted 5.895 (in Pixels) average IMCs size, 19.875 N/mm2 YS and 22.480 N/mm2 UTS for SAC305 alloy at 140°C thermally aged temperature. Originality/value From the experimental and simulated results, it is evident that the fuzzy-based developed algorithm can be used effectively to predict the IMCs size and mechanical properties of SAC305 at various aging temperatures, for the first time.

scholarly journals The Glass Transition Temperature and Temperature Dependence of Activation Energy of Viscous Flow of Ovalbumin

2016 ◽  
Vol 39 (1) ◽  
pp. 13-25
Author(s):  
Karol Monkos
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscous Flow ◽  
Solvent Interactions ◽  
Model Free ◽  
Free Volume Model ◽  
Wide Range ◽  
Different Temperatures

Abstract The paper presents the results of viscosity determinations on aqueous solutions of ovalbumin at a wide range of concentrations and at temperatures ranging from 5°C to 55°C. On the basis of these measurements and three models of viscosity for glass-forming liquids: Avramov’s model, free-volume model and power-law model, the activation energy of viscous flow for solutions and ovalbumin molecules, at different temperatures, was calculated. The obtained results show that activation energy monotonically decreases with increasing temperature both for solutions and ovalbumin molecules. The influence of the energy of translational heat motion, protein-protein and protein-solvent interactions, flexibility and hydrodynamic radius of ovalbumin on the rate of decrease in activation energy with temperature has been discussed. One of the parameters in the Avramov’s equation is the glass transition temperature Tg. It turns out that the Tg of ovalbumin solutions increases with increasing concentration. To obtain the glass transition temperature of the dry ovalbumin, a modified Gordon-Taylor equation is used. Thus determined the glass transition temperature for dry ovalbumin is equal to (231.8 ± 6.1) K.

Density of Deep Bandgap States in Amorphous Silicon From the Temperature Dependence of Thin Film Transistor Current

1994 ◽  
Vol 336 ◽  
Author(s):  
T. Globus ◽  
H. C. Slade ◽  
M. Shur ◽  
M. Hack
Keyword(s):  
Thin Film ◽  
Activation Energy ◽  
Amorphous Silicon ◽  
Conduction Band ◽  
Energy Gap ◽  
Localized States ◽  
Flat Band ◽  
Gate Bias ◽  
Density Of Localized States ◽  
Wide Range

ABSTRACTWe have measured the current-voltage characteristics of amorphous silicon thin film transistors (a-Si TFTs) over a wide range of temperatures (20 to 160°C) and determined the activation energy of the channel current as a function of gate bias with emphasis on the leakage current and subthreshold regimes. We propose a new method for estimating the density of localized states (DOS) from the dependence of the derivative of activation energy with respect to gate bias. This differential technique does not require knowledge of the flat-band voltage (VFB) and does not incorporate integration over gate bias. Using this Method, we have characterized the density of localized states with energies in the range 0.15–1.2 eV from the bottom of the conduction band and have found a wide peak in the DOS in the range of 0.8–0.95 eV below the conduction band. We have also observed that the DOS peak in the lower half of the bandgap increases in magnitude and shifts towards the conduction band as a result of thermal and bias stress. We also measured an overall increase in the DOS in the upper half of the energy gap and an additional peak, centered at 0.2 eV below the conduction band, which appear due to the applied stress. These results are in qualitative agreement with the defect pool Model [1,2].

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