scholarly journals Temperature Self-Compensated Strain Sensors based on MWCNT-Graphene Hybrid Nanocomposite

2019 ◽  
Vol 3 (4) ◽  
pp. 96 ◽  
Author(s):  
Rajarajan Ramalingame ◽  
Jose Roberto Bautista-Quijano ◽  
Danrlei de Farias Alves ◽  
Olfa Kanoun
Keyword(s):  
Temperature Coefficient ◽  
Carbon Nanomaterials ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Gauge Factor ◽  
Positive Temperature ◽  
Hybrid Nanocomposite ◽  
Resistance Change ◽  
Influence Of Temperature ◽  
Dispersion Quality

Sensors based on carbon nanomaterials are gaining importance due to their tunable properties and their potentially outstanding sensing performance. Despite their advantages, carbon-based nanomaterial sensors are prone to cross-sensitivities with environmental factors like temperature. Thus, to reduce the temperature influence on the sensing material, compensation and correction procedures are usually considered. These methods may require the use of additional sensors which can themselves be subject to residual errors. Hence, a more promising approach consists of synthesizing a material that is capable of self-compensating for the influence of temperature. In this study, a hybrid nanocomposite based on multi-walled carbon nanotubes (MWCNT) and graphene is proposed, which can compensate, by itself, for the influence of temperature on the material conductivity. The hybrid nanocomposite material uses the different temperature behavior of MWCNTs, which have a negative temperature coefficient, and graphene, which has a positive temperature coefficient. The influence of the material ratio and dispersion quality are investigated in this work. Material composition and dispersion quality are analyzed using Raman spectroscopy and scanning electron microscopy (SEM). A composition of 70% graphene and 30% MWCNT exhibits a nearly temperature-independent hybrid nanocomposite with a sensitivity of 0.022 Ω/°C, corresponding to a resistance change of ~1.2 Ω for a temperature range of 25 to 80 °C. Additionally, a simple investigation of the strain sensing behavior of the hybrid material is also presented. The hybrid nanocomposite-based, thin-film strain sensor exhibits good stability over 100 cycles and a significantly high gauge factor, i.e., 16.21.

Temperature Dependence of Impact Ionization Coefficients in 4H-SiC

2014 ◽  
Vol 778-780 ◽  
pp. 461-466 ◽  
Author(s):  
Hiroki Niwa ◽  
Jun Suda ◽  
Tsunenobu Kimoto
Keyword(s):  
Temperature Dependence ◽  
Temperature Coefficient ◽  
Breakdown Voltage ◽  
Elevated Temperatures ◽  
Phonon Scattering ◽  
Impact Ionization ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Ionization Coefficients

Impact ionization coefficients of 4H-SiC were measured at room temperature and at elevated temperatures up to 200°C. Photomultiplication measurement was done in two complementary photodiodes to measure the multiplication factors of holes (Mp) and electrons (Mn), and ionization coefficients were extracted. Calculated breakdown voltage using the obtained ionization coefficients showed good agreement with the measured values in this study, and also in other reported PiN diodes and MOSFETs. In high-temperature measurement, breakdown voltage exhibited a positive temperature coefficient and multiplication factors showed a negative temperature coefficient. Therefore, extracted ionization coefficient has decreased which can be explained by the increase of phonon scattering. The calculated temperature dependence of breakdown voltage agreed well with the measured values not only for the diodes in this study, but also in PiN diode in other literature.

Influence of CF on PTC Properties of LDPE/Carbon Fiber Composites

2014 ◽  
Vol 1056 ◽  
pp. 20-24 ◽  
Author(s):  
Wen Long Zhang ◽  
Yu Ping Wan ◽  
Ya Jie Dai ◽  
Yan Gao ◽  
Chen Wang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Temperature Coefficient ◽  
Low Cost ◽  
Negative Temperature ◽  
Treatment Method ◽  
Positive Temperature Coefficient ◽  
Carbon Fiber Composites ◽  
Positive Temperature ◽  
Short Lifespan ◽  
Cost Characteristics

PO/CB (Polyolefin/Carbon Black) PTC (Positive Temperature Coefficient) composite with easy processing, low cost characteristics has been applied widely. But it suffered from a relatively short lifespan because of its NTC (Negative Temperature Coefficient) effect and low PTC intensity. In order to overcome this shortcoming, the CF was calcination-treated to prepare LDPE/CF (Low Density Polyethylene/Carbon Fiber) PTC composite. Influence of length, content and treatment method of CF on PTC properties of composites was investigated. Results showed that 0.5mm length CF in composites had higher PTC intensity than that of 2mm length CF. PTC intensity of the composites was enhanced more effectively by calcination treated CF compared to the untreated CF. The maximum PTC intensity was 8.1 when CF’s content was at 8wt%.

scholarly journals Development of Auto Thermal Control Device For Space Air - Conditioning

2021 ◽  
pp. 193-204
Author(s):  
Akinde Olusola Kunle ◽  
Maduako Kingsley Obinna ◽  
Akande, Kunle Akinyinka ◽  
Adeaga Oyetunde Adeoye
Keyword(s):  
Temperature Coefficient ◽  
Room Temperature ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Thermal Control ◽  
Positive Temperature Coefficient ◽  
Control Device ◽  
Thermal Source ◽  
Positive Temperature ◽  
Ntc Thermistor

Auto Thermal Control device is an electronic based device which employs the application of temperature sensors to controlling household appliances without human interference directly. In this work, thermal source is used to regulate electrical fan and room heater depending on ambient temperature. The room heater, which is adjusted to a set temperature, switches ‘ON’ when the temperature of a room is low (cold). While the same is switches ‘OFF’ with increase in the room temperature. This triggers ‘ON’ an electric fan at different speeds, and thus cools the room. A temperature sensor, tthermistor, monitors change in room temperature. Two types of thermistor exists: Positive Temperature Coefficient, PTC. An increasee in the resistance of PTC results in increasee in temperature). In the Negative Temperature Coefficient, NTC; a decreasee in resistance yields to temperature increase. This article explored a NTC thermistor. The design could be a ready product in the market of the developing nation where environmental automation is yet fully deployed.

Experimental Verification of a Self-Triggered Solid-State Circuit Breaker Based on a SiC BIFET

2017 ◽  
Vol 897 ◽  
pp. 665-668
Author(s):  
Matthaeus Albrecht ◽  
Andreas Huerner ◽  
Tobias Erlbacher ◽  
Anton J. Bauer ◽  
Lothar Frey
Keyword(s):  
Solid State ◽  
Temperature Coefficient ◽  
High Voltage ◽  
Circuit Breaker ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Solid State Circuit ◽  
Current Voltage ◽  
Solid State Circuit Breaker

In this work, the feasibility of the Bipolar-Injection Field Effect-Transistor (BIFET) [5] in two different Dual Thyristor type circuits [4] for an application as solid-state circuit breaker (SSCB) is experimentally verified. The Dual Thyristor type circuits are assembled from discrete silicon JFETs and a silicon carbide BIFET and are electrically characterized at various temperatures. The current-voltage characteristic shows the expected regenerative self-triggered turn-off capability under over-currents and the option to control the turn-off current by a passive resistor network. The issue with the adverse positive temperature coefficient of the trigger-current can be solved by putting the SiC BIFET in a cascode arrangement with a silicon Dual Thyristor. In this configuration the SiC BIFET provides the high voltage blocking capability and the silicon Dual Thyristor with its negative temperature coefficient controls the trigger-current. Transient analyses of both circuits indicate fast switching times of less than 50 μs seconds. It is demonstrated for the first time, that the SiC BIFET, due to its normally-on behaviour, used in a Dual Thyristor type circuit is a promising concept for self-triggered fuses in high current and high voltage applications.

Design for high-performance functional composite thermistor materials by glass/ceramic composing

1999 ◽  
Vol 14 (7) ◽  
pp. 2993-2996 ◽  
Author(s):  
D. J. Wang ◽  
J. Qiu ◽  
Z. L. Gui ◽  
L. T. Li
Keyword(s):  
Temperature Coefficient ◽  
Glass Ceramic ◽  
High Performance ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Functional Composite ◽  
Performance Functional ◽  
Temperature Coefficient Of Resistivity

A negative temperature coefficient–positive temperature coefficient (NTC-PTC) composite thermistor with high performance was designed by glass/ceramic composing. The material exhibited low resistivity and a large negative temperature coefficient of resistivity. The minimum resistivity was the magnitude of 102 Ω cm, and the negative temperature coefficient of resistivity was better than −3% °C−1. The results showed that the large negative temperature coefficient of resistivity was closely related to the glass phase, and the NTC-PTC functional composite material was a kind of grain-boundary–controlled material.

Swelling and electrical properties of LLDPE reinforced by SWCNTs nanocomposites for radiation and sensors applications

2019 ◽  
pp. 089270571987920
Author(s):  
AM Abd Elbary ◽  
MT Tammam ◽  
NI Aljuraide
Keyword(s):  
Electrical Properties ◽  
Temperature Coefficient ◽  
Irradiation Dose ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Γ Irradiation ◽  
Weight Percentage ◽  
Casting Technique ◽  
Walled Carbon Nanotubes

Linear low-density polyethylene (LLDPE) incorporated with single-walled carbon nanotubes (SWCNTs) by mistreatment casting technique. The result of various weight percentage loadings of SWCNTs on the swelling and electrical properties of LLDPE/SWCNTs nanocomposite also γ-irradiation effects had been investigated. It was found that, at low concentration, it uniformly disperses into an LLDPE matrix and provides LLDPE/SWCNTs nanocomposites with abundant improved electrical properties by nine orders of magnitude. Positive temperature coefficient of conductivity (PTCC)/negative temperature coefficient of conductivity (NTCC) was affected by the SWCNT contents. Transmission electron microscopy and scanning electron microscope techniques were used to investigate the dispersion of SWCNTs in the LLDPE matrix. Linear exceptional modification within direct current electrical conduction of percolative threshold-loaded LLDPE as a perform of γ-irradiation dose will be used as a nontoxic, easy, inexpensive, and sensitive method to evaluate the irradiation dose in range 10 Gy–1 kGy also can be used in fabrication of firing sensors with various ranges of temperatures.

scholarly journals Effect of Temperature on the I-V Characteristics of a Polycrystalline Solar Cell

2016 ◽  
Vol 3 (1) ◽  
pp. 35 ◽  
Author(s):  
Indra Bahadur Karki
Keyword(s):  
Temperature Coefficient ◽  
Short Circuit ◽  
Negative Temperature ◽  
Short Circuit Current ◽  
Positive Temperature Coefficient ◽  
Open Circuit ◽  
Outdoor Environment ◽  
Effect Of Temperature ◽  
Positive Temperature ◽  
Full Spectrum

<p>The present paper reports the temperature dependencies of full-spectrum photovoltaic parameters for poly-crystalline PV module. The measurements were performed under outdoor environment conditions. The most interesting feature that was observed for these devices was that above a cell temperature of 20°C the positive temperature coefficient observed for the short-circuit current exceeds in magnitude the negative temperature coefficient that was found for the open-circuit voltage. This means that, unlike the situation for conventional PV devices, these cells actually exhibit decrease in efficiency with increasing temperature (reaching a value of 0.05 % at 60°C).</p><p>Journal of Nepal Physical Society Vol.3(1) 2015: 35-40</p>

Self-Contained Intelligent Sensor-Actuator for Temperature Control

2002 ◽  
Author(s):  
A. M. Al-Jumaily ◽  
H. Kadhum
Keyword(s):  
Temperature Coefficient ◽  
Temperature Control ◽  
Conductive Polymer ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Intelligent Sensor ◽  
Conductive Composites ◽  
Sensor Actuator ◽  
Wide Range

Some electrically conductive polymer composites show positive temperature coefficient behavior during one temperature range followed by negative temperature coefficient behavior during the next range. The change normally occurs at a well-defined switching temperature. This paper proposes to use this phenomenon to develop an intelligent sensor-actuator device suited for temperature control applications. Two conductive composites were prepared and their switching temperatures were determined experimentally. Then a heated tube was made, with one of these composites as the heating element, and tested for the sensing-actuation control action. The results are very promising for future development of a wide range of such devices.

Study on the Temperature-Sensitive Properties of Carbon Fiber-Reinforced Mortar

2011 ◽  
Vol 675-677 ◽  
pp. 1167-1170 ◽  
Author(s):  
Xiao Yan Liu ◽  
Ai Hua Liu ◽  
Feng Wei ◽  
Wu Yao
Keyword(s):  
Carbon Fiber ◽  
Temperature Coefficient ◽  
Initial Period ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Temperature Sensitive ◽  
Thermal Sensor ◽  
Positive Temperature ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced

Carbon fiber (~5mm long)-reinforced mortar is found to be an effective thermal sensor. In this paper, relations between temperature change and resistivity of carbon fiber- reinforced mortar (CFRM for short) with different carbon fiber contents (0.4%~1.2% by mass of cement) are studied. The results show that during the initial period, the resistivity decreases when the temperature increases (Negative Temperature Coefficient effect). After the temperature reaches a certain value, the resistivity increases when the temperature increases (Positive Temperature Coefficient effect). Besides, with the change of carbon fiber content, the transit temperature of NTC/ PTC effect also changes. Based on the experimental results, the CFRM shows a potential use as a thermal sensor. The mechanisms of temperature- sensitive properties and NTC/ PTC transition are also discussed.

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