Microwave inspection

Other NDE Methods The following methods also have applications magnetic field testing, microwave inspection, thermal inspection, and holography. 

Almost all microwave methods are non-contact [1] and allow simultaneous measurement of the magnitude and the frequency of vibrations. The distance between the inspected surface and microwave sensor can vary from several millimeters to a few meters. However, the accuracy of the measurement of vibration magnitude also depends on a distance between the microwave sensor and the object as well as the shape of the inspected surface. 

The intensity of the absorption of microwave energy is a measure the abundance of that isotope. The potency of the NMR spectroscopy is not only its ability to quantify the concentration of an isotope, but to check the enviromnent into which an isotope is embedded. This is possible because the magnetic resonance and thus the absorption frequency prove to be sensitive to the spins of neighboring atoms and to structural features of the probe. Therefore, NMR spectroscopy is more a tool for scientific structural analyses than for daily food (colorant) inspection. For a detailed study of the NMR techniques used in food science we recommend books by Macomber and Pochapsky. - ... 

We have thus far treated the K (n + 2)s states as having no Stark shifts. While they have no first order Stark shift, they do have a second order shift due to their dipole interaction with the p states, which are removed from the s states by energies large compared to the microwave frequency. The microwave field does not produce appreciable sidebands of the s state since it has no first order Stark shift. However, it does induce a Stark shift to lower energy. Not surprisingly the Stark shift produced by a low frequency microwave field of amplitude E is the same as the second order Stark shift produced by a static field Es/j2, they have the same value of (E2). Careful inspection of Fig. 10.9 reveals that the resonances observed with high microwave powers shift with power. 

It is hardly surprising that, as the microwave power is raised, higher order multiphoton processes are observed. On the other hand, it may be surprising that for each m 0 the cross sections first increase then decrease with microwave power. For example, the m = cross section is clearly zero in the lowest trace. Similarly, the m = 0 cross section vanishes in the trace one above the lowest but reappears in the lowest trace. Such behavior, typical of the strong field regime, is not predicted by perturbation theory. Close inspection of Fig. 15.5 reveals that the positions of the collisional resonances shift to lower static field as the microwave power is raised. Finally, in contrast to the usual observation of broadening with increased power, the (0,0)m resonances, which are well isolated from other resonances, develop from broad asymmetric resonances to narrow symmetric ones as the microwave power is raised. 

The second test, developed by the Society of the Plastics Industry, involved preparing an amount of bacon that covered at least 50% of the dinner plate surface area [2], The plate with the bacon layer was heated in a microwave oven set at full power until the temperature at the center of the plate area reached 121°C ( 5°C). The time period required to reach this temperature within the bacon fat was 5 min on the microwave unit used for this test Immediately after the cooking cycle, the plate was cleaned on the lower rack of an automatic dishwasher. The dishwasher cycle was set at normal and included a heated dry cycle. The water temperature reached 66°C ( 5°C). Once the cycle was complete, the plate was inspected for surface blemishes such as cracks or blisters. This test is considered the most severe of the three due to the extreme localized heat generated, which causes the difference between the thermal coefficient of expansion for the two materials to shear the interface resulting in delamination. 

High-power microwave antennae should not be inspected when energized or directed toward inhabited areas. Flammable materials stored in metallic containers should not be left in microwave-induced magnetic fields. A warning device should be provided to microwave equipment to indicate when it is radiating. 

The hazards associated with inappropriate use of microwave equipment cannot be entirely prevented by interlocking devices and other safeguards. However, the risk can be minimized if the analyst continually inspects the system to ensure that the equipment is maintained in safe working order. If any portion of the microwave unit such as door seal or vessel casing becomes damaged by a serious event such as an acid spill, prolonged wear or impact, the safety of the equipment should be re-assessed before it is returned to service. 

The key point about assessing and defining process and product state similar to the machine operators way, is having objective information about the product quality. In the presented approach, the information from the optical inspection system was used to define characteristic situations based on the profile quality (the kind, distribution and quantity of defects) and the process parameters measured and stored by the automation system. A situation or case is thus characterized, among other things, by the aforementioned profile quality, the kind of profile that is produced, the used rubber-mixture, environmental data like air pressure or humidity, the values and latest progression of physical process parameters hke extruder-temperature, power of microwave heating or speed of conveyor-belts and the countermeasures that are taken by the machine operators. 

Coming up, sir. I got us a couple of thermo dump panel inspection mechanoids on microwave circuits. Guess the possessed didn t bother targeting those relays."... 

Electromagnetic methods such as eddy current, capacitance, microwaves, and terahertz radiation are not traditional inspection methods for composites, but they can be used in some circumstances [36]. Microwaves (300 MHz—300 GHz, 1000—1 mm) and terahertz (300 GHz—3 THz, 1—0.1 mm) are applicable to fiberglass composite inspection and have been successful at the detection of damage and internal features [37—45]. However, electromagnetic radiation at these wavelengths does not penetrate conductive materials. For CFRP, which is mildly conductive, they are only useful for sensing very near the surface. Capacitance measurements can be used to measure dielectric property changes in composites such as moisture uptake or cure condition. 

LCPs can be used in thin layers or at low concentrations in blends to make cost-effective high barrier films and containers. LCP barriers have advantages over aluminized plastics and metal foil because the LCP layers can be thermo-formed, they are microwavable, recycling is easier, and metal detection systems can be used to inspect packaged foods. 

High-powered microwave equipment must be grounded to reduce electrical hazards. Metal objects may build a charge from the electrical field of the microwave equipment. Interlocks on doors protect access to hazardous microwave locations. The interlocks prevent unauthorized access to hazardous microwave locations. The interlocks require frequent inspections and testing to ensure they are working properly. Lockout and tagout procedures are important for servicing of microwave equipment. 

In the manufacture of plant and machinery and subsequent periodic inspections and tests, testing is normally non-destructive and a number of specialised techniques have been developed. Equipment is now available to enable visual inspections to be carried out of inaccessible places using fibre optics and remote-controlled television. A major aim of testing is to check the condition of the material of which the plant is constructed and to identify faults that cannot be seen by eye. Special detection techniques used to highlight the weaknesses orfauits in the material include the use of magnetic particles, penetrant dyes, X-ray and gamma-ray sources, ultrasonic vibrations, microwave and infra-red rays. 

Many processes and inspection procedures depend on radiation-emitting substances and equipment. Potential sources of exposure include radiographic examination of equipment smoke detectors using alpha-emitting radioisotopes radioisotopes used as tracers in fluid flow and biochemical analysis radiation-based level and density instruments microwave ovens industrial lasers... 

The peak positions of the spectra illustrated in Figure 13 vary with the Zeeman field, and numerical assignments to spin Hamiltonian parameters based on inspection and a Townes-Dailey ZF-NQI interpretation will yield incorrect values of s Qqzz and Tj. The exact cancellation-like spectral profile is retained over a wide span of microwave frequencies and one does not a priori know from a single ESEEM spectrum whether one is near true exact cancellation. In other words, one cannot simply tune up the spectrometer, locate a frequency/field combination that... 

Equipment which produces microwave radiation can usually be shielded to protect the users. If size and function prohibits this, restrictions on entry and working near an energised microwave device will be needed. Metals, tools, flammable and explosive materials should not be left in the electromagnetic field generated by microwave equipment. Appropriate warning devices should be part of the controls for each such appliance. Commercially-available kitchen equipment is subject to power restrictions and controls over the standard of seals to doors, but regular inspection and maintenance by manufacturers is required to ensure that it does not deteriorate with use and over time. 

OSHA s efforts to minimize or eliminate workers exposure to microwave popcorn manufacturing hazards include inspection targeting, directions for controlling chemical hazards, and extensive compliance assistance. Inspections conducted under this NEP will target facilities where workers are manufacturing or processing microwave popcorn. 

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