Microwave attenuation

A high temperature thermocouple uses sihcon carbide (146). It is also used in lightning arrestors to protect high tension power lines, and in high loss factor microwave attenuators (147). 

Disposal BS and ASTM methods Range of methods including Microwave attenuation Capacitance Resistivity Infra-red absorption Neutron moderation... 

Investigation of the Feasibility of Measuring the Chamber Temperature of Solid Propellant Rocket Motors by Using Microwave Attenuation Measurements , AFOSR-70-2444TR, Contract F44620-68-C-022, Utah Univ, Salt Lake City (1970) 33) M. Venugopalan, Reactions... 

The unit works on the principal that the microwave attenuation of a strip transmission line depends upon the loss factor of the material with which it is in contact. Data indicates accuracies of 5% can be attained by the hand-held instruments, depending upon the range of fat measured. The instruments sell for approximately 5000.00. Copies of references are available from Distell. 

If the tube is filled with a dielectric material, the cut-off frequency will change depending upon the values of e and e". Thus, changes in constituency can be determined by measuring the cut-off characteristics of the propagating signal. In the implementation of the GMS system, the microwave attenuation of the measurement cell, through which is passed the process... 

The continuous measurement of moisture in coal has been accomplished by (1) electrical conductivity, (2) dielectric constant, (3) microwave attenuation, (4) neutron scattering, (5) nuclear magnetic resonance, (6) infrared, and (7) thermal conductivity (Hampel, 1974). 

This method has been criticized because the probe, in drawing current, disturbs the normal electron and ion distributions. In one alternative solution that has been suggested, a floating double probe is used (J2). Just how important this disturbance is, still seems to be a matter of some discussion. Other methods, such as microwave attenuation, have been tried for measuring electron temperatures, but little has been published about the techniques. 

As a rule, microwave attenuators introduce phase shift as well as attenuation. An exception is the type of attenuation known as rotary vane , which has negligible phase shift. Some attenuator manufacturers have achieved fairly constant phase shift for microwave coaxial structures. Often the level set attenuator in the reference arm is of lower quality with large phase shift, but the operator encounters little difficulty because the reference level is seldom changed. The reader can appreciate the frustration that would occur if for every change in the main attenuator setting an accompanying phase shift were to occur. 

Increased use of digitally controlled components not only for convenience but also to compensate for variations in oscillator power output with microwave frequency, microwave phase with attenuation, and microwave attenuation with microwave frequency. 

Key words aluminum nitride, silicon carbide, sinterability, thermal conductivity, microwave attenuation... 

The primary objective of this work is to prepare and characterize AlN-SiC composites by hot-pressing and explain the relationship between the content of attenuator SiC and the sinterability, thermal conductivity, microwave attenuation performance of AlN-SiC composites. 

Sinterability, Thermal Conductivity and Microwave Attenuation Performance of AIN-SiC... 

Fig. 5 shows the microwave attenuation characteristics of AlN-SiC composites within the range of 2-20GHz. Samples with less than 20wt%SiC show narrow frequency band attenuation performance... 

Fig. 5 Microwave attenuation curves of AIN-SiC composites with different SiC content l-0wt%SiC 2-20wt%SiC 3-40wt%SiC 4-60wt% 5-70wt% SiC 6-80wt% SiC...

A microwave attenuation technique was used to monitor in-situ oil/water saturations during enhanced recovery for each alkaline core flood. 

The present study utilizes a microwave attenuation tech nique to study oil bank formation and propagation during linear core tests. This technique, first developed by Parsons (12), was employed to monitor the dynamic in-situ water concentration during the alkaline core flooding experiments. 

Parsons, R. W., "Microwave Attenuation—A New Tool for Monitoring Saturations in Laboratory Flooding Experiments", SPE J. August 1975, pp. 302-310. 

On-line moisture monitors, which are based on infra-red absorption, nuclear magnetic resonance, capacitance and microwave attenuation are used in numerous process industries. The applicability of these techniques to the coal preparation industry has been reviewed (13,14). The CONAC and "Elemental Analyzer" units use a microwave attenuation method for the moisture measurement. This information is used to correct the PNAA hydrogen assay data in order to calculate the hydrogen content of the coal. Kay-Ray, Inc., (Arlington Heights, Illinois) has developed an instrument that measures the moisture content of a coke stream and uses a combination of microwave and gamma ray attenuation measurements. 

In the field of emulsions characterization, it is well known that dilution may create perturbation on the surface properties of the droplets and on interactions between the droplets. To give an example, matter transfers resulting from osmotic shocks may occm causing polydispersity changes as has been shown when such events are required (5,6). In fact, very few techniques avoid dilution, namely, dielectric or hert-zian spectroscopy (7-9), rheology (2), conductimetry (6,7), and more recent ones based on acoustical methods (10), focussed beam reflectance (11,12), or microwave attenuation (13). All these techniques are complementary and new techniques are always wel come. 

Moisture sensors/methods standard gravimetric method (SGM) microwave phase shift (MPS) microwave attenuation (MA) near-infrared (NIR) capacitance and conductivity (CC) radiofrequency transmission (RFT) neutron moderation activation (NMA) low resolution (LR) direct physical measurement (DPM) based on the drag force principle. 

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