Temperature Gradient Research Papers - Academia.edu (original) (raw)

The present paper focuses on the heat transfer problem that describes the heat conduction effects in an OPGW submitted to short-circuit. An analytical solution is proposed which accounts for the effect of the temperature gradients in the... more

The present paper focuses on the heat transfer problem that describes the heat conduction effects in an OPGW submitted to short-circuit. An analytical solution is proposed which accounts for the effect of the temperature gradients in the aluminum covered steel wires, and the contact thermal resistance in the effective contact surface between the fiber extruded aluminum tube and the aluminum covered steel wires. The numerical results are compared with results previously obtained and reported in the 54th IWCS Conference, for an OPGW with armored steel wires with the same dimensions. The analytical solution is expressed in terms of integral equations, which can be numerically solved in terms of the heat flux, as well as the temperature of the tube and the wires. The present approach is appropriate and effective to make design parameter sensibility analysis as well as for parameter estimation of the thermal contact resistance. The numerical results reported here show that the aluminum l...

The discrete ordinates method (DOM) and discrete transfer method (DTM) were evaluated from the viewpoints of both predictive accuracy and computational economy by comparing their predictions with exact solutions available from a... more

The discrete ordinates method (DOM) and discrete transfer method (DTM) were evaluated from the viewpoints of both predictive accuracy and computational economy by comparing their predictions with exact solutions available from a box-shaped enclosure problem with steep ...

We analysed the electron-hole or, in other words, branch imbalance (BI) and the related electric potential Vimb which may arise in a mesoscopic superconductor/normal-metal (S/N) structure under non-equilibrium conditions in the presence... more

We analysed the electron-hole or, in other words, branch imbalance (BI) and the related electric potential Vimb which may arise in a mesoscopic superconductor/normal-metal (S/N) structure under non-equilibrium conditions in the presence of a supercurrent. Non-equilibrium conditions can be created in different ways: a) a quasiparticle current flowing between the N reservoirs; b) a temperature gradient between the N reservoirs and no quasiparticle current. It is shown that the voltage Vimb oscillates with the phase difference varphi. In a cross-geometry structure the voltage Vimb arises in the vertical branch and affects the conditions for a transition to the π-state.

: Sutherland's theoretical expression for the absolute or dynamic viscosity of a gas has been modified to represent experimental viscosity data for air. The resulting semi-empirical equation accurately describes measured viscosities... more

: Sutherland's theoretical expression for the absolute or dynamic viscosity of a gas has been modified to represent experimental viscosity data for air. The resulting semi-empirical equation accurately describes measured viscosities of air for temperatures ranging from the boiling point at 78 K to molecular dissociating conditions at 2500 K. Discrepancies between measured values and semi-empirical results rarely exceed 2%. Other more limited expressions for the viscosity of air are also compared to measured viscosity data and discussed. (Author)

In this research p- type thin films based on Bi0.5Sb1.5Te3 compound were developed for radiation sensors. The films were grown by two physical vapor deposition methods, namely an electron gun and flash evaporation techniques. The... more

In this research p- type thin films based on Bi0.5Sb1.5Te3 compound were developed for radiation sensors. The films were grown by two physical vapor deposition methods, namely an electron gun and flash evaporation techniques. The parameters of the different processes were examined and compared in order to maximize the c axis preferred orientation of the film as well as its thermoelectric figure of merit. The crystal structure and Seebeck coefficient of these films were investigated at room temperature. The electrical conductivity and Hall coefficient were measured from 80 to 300 K. The results indicate a high c axis preferred orientation for the films developed by the electron gun technique accompanied by a power factor in the vicinity of 30 µW cm-1 K-2 at room temperature. When an infrared signal hits the sensor it is absorbed and causes a temperature gradient along the thermoelectric transducer, by that, a Seebeck voltage is generated. It is very important to use an extremely thin...

IDA Indoor Climate and Energy (ICE) is a recently developed tool for simulation of thermal comfort, indoor air quality and energy consumption in buildings. It covers a range of advanced phenomena such as integrated airflow and thermal... more

IDA Indoor Climate and Energy (ICE) is a recently developed tool for simulation of thermal comfort, indoor air quality and energy consumption in buildings. It covers a range of advanced phenomena such as integrated airflow and thermal models, CO 2 modeling, and vertical temperature gradients. It has a multi-level user interface to accommodate different types of users. It is primarily intended for HVAC designers and architects, but is also appreciated by educators and researchers. In this paper the advantages of the modern simulation tool are shown in prediction of indoor climate. KEYWORDS Modeling, comfort, energy, displacement ventilation

A fiber Brag grating sensor interrogator has been developed which is capable of gathering vectors of information from individual fiber Bragg gratings by capturing the full optical spectrum 3 kHz. Using a field programmable gate array with... more

A fiber Brag grating sensor interrogator has been developed which is capable of gathering vectors of information from individual fiber Bragg gratings by capturing the full optical spectrum 3 kHz. Using a field programmable gate array with high speed digital-to-analog converters and analog-to-digital components, plus a kilohertz rate MEMS optical filter, the optical spectrum can be scanned at rates in excess of 10 million nanometers per second, allowing sensor sampling rates of many kilohertz while maintaining the necessary resolution to understand sensor changes. The autonomous system design performs all necessary detection and processing of multiple sensors and allows spectral measurements to be exported as fast as Ethernet, USB, or RS232 devices can receive it through a memory mapped interface. The high speed - full spectrum - fiber Bragg grating sensor interrogator enables advanced interrogation of dynamic strain and temperature gradients along the length of a sensor, as well as the use of each sensor for multiple stimuli, such as in temperature compensation. Two examples are described, showing interrogation of rapid laser heating in an optical fiber, as well as complex strain effects in a beam that had an engineered defect.