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Metallic stirrers are commonly used in mode-stirred reverberation chambers but are less common in microwave ovens, because the use of a metallic axis creates a coaxial port in the cavity wall where the axis is introduced, which may result in significant microwave leakage levels. However, due to electromagnetic, mechanical, temperature, or chemical requirements, metallic axes must be used in some cases. In this paper, we present a high power coaxial filter that enables the use of metallic stirrers in microwave applications. The filter employs two-port coaxial cavities that are analyzed to determine their design parameters. These cavities are coupled via coaxial lines to achieve proper attenuation levels. The cavities were designed using commercial electromagnetic (EM) software, and a filter prototype was validated using vector network analyzer (VNA) measurements. The simulated and measured results show that a three-stage configuration can achieve attenuations greater than 70 dB at the 2.45 GHz ISM band, allowing the use and external handling of the metallic axis inserted into microwave ovens with negligible microwave radiation leakage.

In this contribution authors show the usage of several coaxial filters that avoid microwave leakage when using metallic mode stirrers within microwave multimode cavities. We describe the simulation schemes and characteristics for the different coaxial filters employed when introducing the metal axis of the mode-stirrer in the applicator. Additionally, the measurement setup that allows to validate the filtering capabilities is also described in detail. Figure 1 shows the cross-section scheme of a typical multimode microwave cavity. A waveguide feeding port is used to introduce the microwave energy in the cavity. The movement of the mode stirrer causes different electric field distribution patterns within the cavity and the material which may result in the reduction of cold and hot spots. Metallic materials are preferred versus dielectric ones to manufacture stirrers because metals are more effective than dielectrics to reflect and stir the microwave energy. However, when the metallic axis of the mode stirrer goes through the cavity walls a coaxial line is generated and the microwave electric field may leak through the coaxial port very easily. Several coaxial filtering structures are evaluated and validated to prevent electric field scaping from the applicator.

Cooling of beverages is of large interest. Here a theoretical idea of how microwave ovens can be usedfor cooling beverages is presented. The proposed theoretical idea based on heat transfer features a microwavesafe (isoprene rubber) torus shaped rubber ring (MWSR) holding a liquid (L) at room temperature. Fullerenoldissolved in acetone (L) inside MWSR (L) will absorb energy directly from the microwave radiation and therebyincrease its temperature. The liquid to be cooled (B) will also absorb energy from the microwave radiation, butthe net effect is the cooling of B as the heat transfer is faster in L than in B due to L’s lower boiling point andheat of vaporization. The cooling fan of the microwave oven facilitates the heat transfer mechanism. Thebeverage B is theoretically cooled from room temperature (20 °C) to around 4 °C in around 58 seconds. Basedon heat absorption of fullerenol—which could be transformed from liquid phase to vapour phase—a beverageliquid (300 g water) in a glass put inside the microwave oven could be cooled (reversely heated) by the heatgenerated by the microwave oven. The user of the proposed method would be able cool 300 ml of beverage toless than 4 °C in just a minute using consumer microwave ovens.

Cooling of beverages is of large interest. Here a theoretical idea of how microwave ovens can be usedfor cooling beverages is presented. The proposed theoretical idea based on heat transfer features a microwavesafe (isoprene rubber) torus shaped rubber ring (MWSR) holding a liquid (L) at room temperature. Fullerenoldissolved in acetone (L) inside MWSR (L) will absorb energy directly from the microwave radiation and therebyincrease its temperature. The liquid to be cooled (B) will also absorb energy from the microwave radiation, butthe net effect is the cooling of B as the heat transfer is faster in L than in B due to L’s lower boiling point andheat of vaporization. The cooling fan of the microwave oven facilitates the heat transfer mechanism. Thebeverage B is theoretically cooled from room temperature (20 °C) to around 4 °C in around 58 seconds. Basedon heat absorption of fullerenol—which could be transformed from liquid phase to vapour phase—a beverageliquid (300 g water) in a glass put inside the microwave oven could be cooled (reversely heated) by the heatgenerated by the microwave oven. The user of the proposed method would be able cool 300 ml of beverage toless than 4 °C in just a minute using consumer microwave ovens.

[EN] The proper use of microwave heating can significantly increase the production cycle time and energy efficiency in industrial heating processes compared to conventional heating methods. The main challenge of this technique is to improve the temperature uniformity in the product exposed to standing waves inside the microwave oven. In opposite to the magnetron, solid-state amplifiers (SSA) offer the possibility to increase the homogeneity by changing the amplitude, frequency and phase with the help of intelligent control methods [1]. In this work, the variation of the frequency and the amplitude of the SSA is considered. The multimode microwave oven used in the experiment has an industrial size of 535 mm x 510 mm x 395 mm (Figure 1). The SSA was operated in the frequency range from 2.4 GHz to 2.5 GHz. It consisted of a new 300 W solid state microwave source from HBH microwave GmbH, Germany. An antenna system was developed based on numerical simulation with CST Microwave Studio. The positions of four loop antennas were optimized to excite at least 90 % of the possible 32 eigenmodes [2] of the unloaded cavity. At the roof of the cavity, an IR camera was installed to observe the temperature distribution of the load during heating. A sheet of paper was used as the thermal load. It was placed on a PTFE plate as a sample holder. Figure 1 exemplary illustrates the comparison of the simulated power distribution with the measured temperature distribution for two representative eigenmodes. As can be expected from the figures, an optimized combination of different modes will lead to a significantly improved temperature uniformity in the material. Latest results obtained with different type of loads will be presented.

[EN] The proper use of microwave heating can significantly increase the production cycle time and energy efficiency in industrial heating processes compared to conventional heating methods. The main challenge of this technique is to improve the temperature uniformity in the product exposed to standing waves inside the microwave oven. In opposite to the magnetron, solid-state amplifiers (SSA) offer the possibility to increase the homogeneity by changing the amplitude, frequency and phase with the help of intelligent control methods [1]. In this work, the variation of the frequency and the amplitude of the SSA is considered. The multimode microwave oven used in the experiment has an industrial size of 535 mm x 510 mm x 395 mm (Figure 1). The SSA was operated in the frequency range from 2.4 GHz to 2.5 GHz. It consisted of a new 300 W solid state microwave source from HBH microwave GmbH, Germany. An antenna system was developed based on numerical simulation with CST Microwave Studio. The positions of four loop antennas were optimized to excite at least 90 % of the possible 32 eigenmodes [2] of the unloaded cavity. At the roof of the cavity, an IR camera was installed to observe the temperature distribution of the load during heating. A sheet of paper was used as the thermal load. It was placed on a PTFE plate as a sample holder. Figure 1 exemplary illustrates the comparison of the simulated power distribution with the measured temperature distribution for two representative eigenmodes. As can be expected from the figures, an optimized combination of different modes will lead to a significantly improved temperature uniformity in the material. Latest results obtained with different type of loads will be presented.

[EN] The proper use of microwave heating can significantly increase the production cycle time and energy efficiency in industrial heating processes compared to conventional heating methods. The main challenge of this technique is to improve the temperature uniformity in the product exposed to standing waves inside the microwave oven. In opposite to the magnetron, solid-state amplifiers (SSA) offer the possibility to increase the homogeneity by changing the amplitude, frequency and phase with the help of intelligent control methods [1]. In this work, the variation of the frequency and the amplitude of the SSA is considered. The multimode microwave oven used in the experiment has an industrial size of 535 mm x 510 mm x 395 mm (Figure 1). The SSA was operated in the frequency range from 2.4 GHz to 2.5 GHz. It consisted of a new 300 W solid state microwave source from HBH microwave GmbH, Germany. An antenna system was developed based on numerical simulation with CST Microwave Studio. The positions of four loop antennas were optimized to excite at least 90 % of the possible 32 eigenmodes [2] of the unloaded cavity. At the roof of the cavity, an IR camera was installed to observe the temperature distribution of the load during heating. A sheet of paper was used as the thermal load. It was placed on a PTFE plate as a sample holder. Figure 1 exemplary illustrates the comparison of the simulated power distribution with the measured temperature distribution for two representative eigenmodes. As can be expected from the figures, an optimized combination of different modes will lead to a significantly improved temperature uniformity in the material. Latest results obtained with different type of loads will be presented.

[EN] The proper use of microwave heating can significantly increase the production cycle time and energy efficiency in industrial heating processes compared to conventional heating methods. The main challenge of this technique is to improve the temperature uniformity in the product exposed to standing waves inside the microwave oven. In opposite to the magnetron, solid-state amplifiers (SSA) offer the possibility to increase the homogeneity by changing the amplitude, frequency and phase with the help of intelligent control methods [1]. In this work, the variation of the frequency and the amplitude of the SSA is considered. The multimode microwave oven used in the experiment has an industrial size of 535 mm x 510 mm x 395 mm (Figure 1). The SSA was operated in the frequency range from 2.4 GHz to 2.5 GHz. It consisted of a new 300 W solid state microwave source from HBH microwave GmbH, Germany. An antenna system was developed based on numerical simulation with CST Microwave Studio. The positions of four loop antennas were optimized to excite at least 90 % of the possible 32 eigenmodes [2] of the unloaded cavity. At the roof of the cavity, an IR camera was installed to observe the temperature distribution of the load during heating. A sheet of paper was used as the thermal load. It was placed on a PTFE plate as a sample holder. Figure 1 exemplary illustrates the comparison of the simulated power distribution with the measured temperature distribution for two representative eigenmodes. As can be expected from the figures, an optimized combination of different modes will lead to a significantly improved temperature uniformity in the material. Latest results obtained with different type of loads will be presented.

The present invention relates to a microwave powered sensor assembly for micro- wave ovens. The microwave powered sensor assembly comprises a microwave antenna for generating an RF antenna signal in response to microwave radiation at a predetermined excitation frequency. A dc power supply circuit of the microwave powered sensor assembly is operatively coupled to the RF antenna signal for extracting energy from the RF antenna signal and produce a power supply voltage. A sensor is connected to the power supply voltage and configured to measure a physical or chemical property of a food item under heating in a microwave oven chamber.

The thesis work is a part of a project where the major goal is to improve the efficiency of the evaluations of microwave ovens at Whirlpool Sweden AB. The purpose of the work has been to develop an automatic control and measurement system for microwave ovens. In an earlier thesis work, a test rig has been developed and this test rig has been further developed to an autonomous system. The software for this system is developed in LabVIEW and interfaces to some measuring instruments has been implemented for the system. As a plan for the programming work, UML-diagrams were created in Visual Paradigm To make it easy for the user to handle the system, a user interface has been created in LabVIEW. The system handles different XML-files: oven profiles and test profiles, which are defined by the user. An oven profile contains coordinates for specific positions at the front of a microwave oven, e.g. button positions and corners. There will be one oven profile per oven model. A test profile contains different stages with position names, operations and time delays. The position names are the names of the positions defined in the oven profile. The results from a measurement will be saved in a CSV-file.

The thesis work is a part of a project where the major goal is to improve the efficiency of the evaluations of microwave ovens at Whirlpool Sweden AB. The purpose of the work has been to develop an automatic control and measurement system for microwave ovens. In an earlier thesis work, a test rig has been developed and this test rig has been further developed to an autonomous system. The software for this system is developed in LabVIEW and interfaces to some measuring instruments has been implemented for the system. As a plan for the programming work, UML-diagrams were created in Visual Paradigm To make it easy for the user to handle the system, a user interface has been created in LabVIEW. The system handles different XML-files: oven profiles and test profiles, which are defined by the user. An oven profile contains coordinates for specific positions at the front of a microwave oven, e.g. button positions and corners. There will be one oven profile per oven model. A test profile contains different stages with position names, operations and time delays. The position names are the names of the positions defined in the oven profile. The results from a measurement will be saved in a CSV-file.

In this reported work it is shown that one of the most employed filtering systems for use in continuous-flow industrial microwave ovens, namely doubly corrugated filters, does not work properly for many values of the electric permittivity of the processed material when it is partially filled. Thus, a novel bandstop filter which solves these inconveniences, based on a combination of metallic irises and double corrugations, is designed by means of CST Microwave Studio® and experimentally validated.

[ESP] La energía de microondas se emplea habitualmente en muchas aplicaciones industriales, científicas y médicas, las cuales requieren frecuentemente la participación de personas en contacto directo con los equipos de microondas. Específicamente, los hornos industriales de microondas suelen emplear puertos abiertos en guía de onda para permitir un flujo continuo del material a procesar. Por esta razón, las cuestiones de seguridad son un aspecto primordial en estos sistemas, con el fin de evitar posibles efectos peligrosos en tejidos humanos debidos a fugas de energía de microondas. Varias alternativas para lidiar con este problema se han propuesto en la literatura técnica. Una de las elecciones más efectivas está basada en filtros corrugados reactivos, los cuales reflejan hacia atrás la energía que intenta escapar del aplicador. Pero en esta tesis se han encontrado algunas limitaciones de estas estructuras, particularmente en lo que se refiere a las propiedades dieléctricas del material procesado. La presente tesis aborda el objetivo de mejorar estos filtros reactivos cuando el horno requiere un flujo continuo de material. Para ello, se proponen nuevas estructuras que solucionan los inconvenientes que presentan los filtros tradicionales, así como algoritmos de optimización que reducen el tiempo de diseño. Adicionalmente, se proponen nuevas técnicas de calibración y caracterización aplicadas a dispositivos en guía de onda. [ENG] Microwave energy is extensively used in many industrial, scientific and medical applications, which frequently require the participation of human beings in direct contact with microwave equipment. Specifically, industrial microwave ovens often employ open-ended waveguide ports in order to allow a continuous flow of the material to be processed. For this reason, safety issues become a main concern in such systems to prevent possible dangerous effects on human tissues due to microwave energy leakage. Some alternatives to deal with this leakage

In this work a new sensor-based self-configurable waveguide bandstop filter that uses a combination of metallic irises and reconfigurable posts for reducing the energy leakage in industrial microwave ovens is presented and validated through a procedure fully based on measurements. Several optimization and reconfiguration alternatives of the moving posts such as genetic algorithms and parametric sweeps are assessed. Results show that good attenuation values can be obtained for all the analyzed scenarios. In particular, genetic algorithms are shown as the best search strategy. Design and optimization times are also reduced when using the proposed filter compared to computer simulations.

The report describes a measuring method for analysis of energy consumption measurement in microwave ovens. Concurrently that the awareness of the environment evolves the demands are growing for more power saving products. This is also counting within the Home Appliance business, which is Whirlpools business area. Whirlpool is therefore interested of launching microwave ovens with documented low power consumption. To be able to implement this, both asserted measuring equipment, that fulfils all demands, and a standard procedure is required. Asthis is a comparatively new business area within microwave oven production, there is no definite standard to follow. There is however a proposal developed by CENELEC. The report describes the suggested measuring method and analyses and evaluates it. Proposal is also given on how to refine the measuring method and evolve it further. The developed measuring equipment is carefully described in the report. The software to the measuring equipment has been developed using National Instrument’s LabVIEW®. LabVIEW® is a powerful and comparatively easy-to-use tool often used when developing measuring systems. The developed hardware’s main task is to detect which heating element (grill, forced air, microwaves) that is active in the microwave oven. This is very useful when verifying programs for cooking in the oven. Eventually it is the authors hope that the system will be used within Whirlpool, and also be developed further.

The report describes a measuring method for analysis of energy consumption measurement in microwave ovens. Concurrently that the awareness of the environment evolves the demands are growing for more power saving products. This is also counting within the Home Appliance business, which is Whirlpools business area. Whirlpool is therefore interested of launching microwave ovens with documented low power consumption. To be able to implement this, both asserted measuring equipment, that fulfils all demands, and a standard procedure is required. Asthis is a comparatively new business area within microwave oven production, there is no definite standard to follow. There is however a proposal developed by CENELEC. The report describes the suggested measuring method and analyses and evaluates it. Proposal is also given on how to refine the measuring method and evolve it further. The developed measuring equipment is carefully described in the report. The software to the measuring equipment has been developed using National Instrument’s LabVIEW®. LabVIEW® is a powerful and comparatively easy-to-use tool often used when developing measuring systems. The developed hardware’s main task is to detect which heating element (grill, forced air, microwaves) that is active in the microwave oven. This is very useful when verifying programs for cooking in the oven. Eventually it is the authors hope that the system will be used within Whirlpool, and also be developed further.

To be able to improve products extensive testing is required in order to find hidden flaws in the design. The earlier flaws are found the higher are the probability that they can be corrected before the product is released onto the market. If the tests could be carried out all hours of the day every day of the week, this would introduce another level of stress to the product. More stress than if the product would be tested only during working days and it may reveal issues that could be corrected to improve the product further. Although a similar test environment already exists at Whirlpool Sweden AB, there are requests to rethink and improve these tests so that the microwave ovens are tested in an environment more close to reality. This thesis will present a concept proposal of how to improve the tests. Further, the thesis will include initial construction of a machine that could perform automated tests with the ability to interpret errors and report them. In the end, the machine should press buttons on the microwave oven, look at the display with a camera, open the door and so on. The mechanics for the machine is bought, so a big part of the thesis will be electronics design. The project will include an embedded system design with a 32-bit ARM micro controller that is going to control the machine. As this part is quite big the thesis will include the hardware design, but not much programming. The hardware design of the embedded system did work as expected, without any revisions. The hardware has been verified by electrical tests and basic software to test the general functions of the hardware. In the future, the hardware needs programming and the machine has to be equipped with a mechanical finger to be able to press buttons. Keywords: Embedded system design, ARM, Cortex-M3, , Linear guide, Stepper motor.

To be able to improve products extensive testing is required in order to find hidden flaws in the design. The earlier flaws are found the higher are the probability that they can be corrected before the product is released onto the market. If the tests could be carried out all hours of the day every day of the week, this would introduce another level of stress to the product. More stress than if the product would be tested only during working days and it may reveal issues that could be corrected to improve the product further. Although a similar test environment already exists at Whirlpool Sweden AB, there are requests to rethink and improve these tests so that the microwave ovens are tested in an environment more close to reality. This thesis will present a concept proposal of how to improve the tests. Further, the thesis will include initial construction of a machine that could perform automated tests with the ability to interpret errors and report them. In the end, the machine should press buttons on the microwave oven, look at the display with a camera, open the door and so on. The mechanics for the machine is bought, so a big part of the thesis will be electronics design. The project will include an embedded system design with a 32-bit ARM micro controller that is going to control the machine. As this part is quite big the thesis will include the hardware design, but not much programming. The hardware design of the embedded system did work as expected, without any revisions. The hardware has been verified by electrical tests and basic software to test the general functions of the hardware. In the future, the hardware needs programming and the machine has to be equipped with a mechanical finger to be able to press buttons. Keywords: Embedded system design, ARM, Cortex-M3, , Linear guide, Stepper motor.

In this work, a novel procedure for increasing the power efficiency of microwave ovens is presented. The procedure consists of 10 iteratively moving the sample within the microwave oven until a maximum average temperature increment is detected across the 11 sample. A new experimental set-up consisting of a multimode microwave cavity, a dielectric tracking system, a microwave power 12 source and a thermographic camera has been built and tested. Results show that it is possible to find optimal positions for the 13 sample within the oven for which microwave power transfer to the sample is maximized

A proliferation of choices available to consumers as they select a major cooking appliance necessitated the development of a Buyer’s Guide which will provide consumers with generic information by which they can compare range cooktops and microwave ovens. The microwave oven is included because it is often used in the place of a cooktop. The Buyer’s Guide for Range Cooktops and Microwave Ovens as an information resource is designed to be used by consumers to assist in making an informed purchase decision. The study was conducted in three phases: 1) identification of items included in the Buyer’s Guide; 2) establishment of test procedures; and 3) focus panel evaluation of the Buyer’s Guide. Phase 1 - Eleven items considered to be important in making purchase decisions were identified by members of the Virginia Retail Merchants Association and by Virginia home economics Extension agents. Items rated as important for inclusion were: purchase price, maintenance, life expectancy, operating costs, energy use, speed of heating, evenness of heating, heat retention, heat recovery, ease of cleaning, and ease of use. Phase 2 - Using standardized test procedures, data were obtained for the radiant coil electric smoothtop to allow the comparison of items found on the Buyer’s Guide with other types of range cooktops (conventional electric coil, gas burner, induction cooktop, smoothtop resistance coil, solid element) and the microwave oven. Phase 3 - Four focus panels were conducted to evaluate the Buyer’s Guide for Range Cooktops and Microwave Ovens for clarity of content, practicality of format, and its usefulness to consumers. The 26 focus panel participants recommended changes which were incorporated into the Buyer’s Guide for Cooktops and Microwave Ovens. They indicated a belief that the Buyer’s Guide would be useful for consumers seeking generic information by which to compare major cooking appliances. Further research is needed to evaluate the Buyer’s Guide for Range Cooktops

The purpose of this study was to identify the extent of adoption of microwave ovens by older adults in Blacksburg, Virginia. Level of adoption was defined and determined as a function of 1) frequency of use of the microwave oven in comparison to the range, and 2) complexity of food preparation. Mere ownership was not considered as an indicator of adoption. Focusing on the final stage of Rogers theory of adoption (1962), three levels of adoption were determined: High, medium, and low. A random sample of 75 adults 65 years and older was selected from the listing of retired personnel in the 1997-98 Virginia Polytechnic Institute and State University faculty and staff directory. Telephone interviews were conducted to collect information regarding current microwave oven usage patterns and decisions for future use and purchase. Relationships between level of adoption, and user characteristics and microwave oven characteristics were statistically tested. Results from the study indicate that 56% of these older adults who own a microwave oven are high adopters; i.e. they used the microwave more than the range and performed high complexity tasks. About 52% reported using the microwave oven more frequently than the range. Nearly all respondents were satisfied with the microwave oven in terms of speed and convenience, while 60% were satisfied with quality of foods cooked in the microwave oven. There was no significant difference in level of adoption with age, gender, health condition, and knowledge of microwave oven use. However, level of adoption was significantly higher among older adults who were "never" married or "previously" married compared to those that were "currently" married. Also, level of adoption was significantly lower among those older adults who had touch controls on their microwave oven compared to those with rotary dials. Other significant results of this study dealt with future use and purchase decisions. About 93% of the respon

Includes bibliographical references and index.

The purpose of the study was to determine the optimum design of microwave ovens to support the Speed Field Feeding concept. The study proceeded in two stages: Phase I, in which the contractor made a study of the cooking system requirements and determined how all requirements can be accomplished, and Phase II in which the contractor studied all problems and determined the optimum methods of solving them. The report summarizes the work on Phase I of the study contract. (Author), See also Phase 2 rept., AD-706 902.

An investigation was made of the use of microwave ovens as part of the U.S. Army's SPEED field feeding system. In Phase I, the general feasibility of meeting the cooking and baking requirements of SPEED with microwave technology was confirmed. In Phase II, the contractor has proceeded to develop design characteristics of the ovens and supporting equipment, and to resolve various problem areas uncovered in the first phase of the contract. (Author), See also Phase 1 rept., AD-706 901.

A review of the literature was undertaken along with a physical survey of microwave ovens being operated at USAF bases. The operation of an oven with (1) interlocks that have been 'jumped' (overridden) or have failed (2) door partially or fully open represents the most serious hazard to operating personnal of these ovens, an evaluation of this situation was performed in the laboratory. Purpose of these studies was to appropriate survey procedure and equipment, and provide guidance for interpretation of survey results. It was concluded that there is very little hazard associated with the normal operation of these ovens, even though some leakage may occur. Periodic surveys of these ovens are necessary to determine if interlocks have failed or have been 'jumped' (overridden), and if significant leakage is occuring. Recommendations are made for survey procedures and equipment to be used. Levels of microwave radiation leakage which require corrective action are presented.

The patent describes a safety load and temperature control system for microwave ovens wherein a variable volume of water is passed through the oven for controlling the amount of energy received by a work piece therein. Microwave energy from magnetron tubes is introduced into the oven chamber for processing a work piece. The variable supply of water within the chamber is increased for small parts being cured and decreased for large parts being cured. The water is passed through a dielectrically transparent vessel within the chamber and is heated by the microwave energy proportional to the heated work piece or part. The temperature of the water leaving the chamber is indicative of the rate of change of the work piece temperature.

Microwave Blanching instructions for a variety of vegetables have recently been published by several sources. More research is needed, however, to establish microwave blanching times that are sufficient to destroy enzymes which cause nutritional and sensory deterioration in frozen vegetables while maintaining optimal quality. In the present study the General Electric Company's recommended blanch times for carrots and green beans were investigated using three microwave ovens. Peroxidase was used as an indicator enzyme for measuring blanching adequacy. It was determined that oven variation had no significant effect on percent residual peroxidase activity in either vegetable (p > 0.05). A large degree of standard deviation in the percent residual peroxidase activity was found among the blanched portions of vegetable. This variation was attributed to the inconsistent levels of peroxidase enzyme in the vegetables themselves. Blanch time had the most significant impact on percent residual peroxidase activity (p < 0.01). After a four-minute blanch, carrots retained approximately 21-25% peroxidase activity and green beans retained approximately 37-46% peroxidase activity. These ranges are much higher than the acceptable level of 5% residual peroxidase activity. Six minutes of blanching for green beans and five minutes of blanching for carrots were required to reduce residual peroxidase activity to acceptable levels. Vegetables with such low peroxidase activity show no deleterious enzyme related changes during frozen storage. Microwave blanching has the potential to be an acceptable alternative to hot water blanching, but further research is needed to optimize microwave blanching procedures.

2002, Technical Summary, PDF, Tech Report, 359, Soils, Microwave devices, Moisture content, Evaluation, Sand, Silts, Clay, Soil aggregates, Soil cement, Geotechnology, Highways, I42: Soil Mechanics, Louisiana, United States, Louisiana Transportation Research Center, Gaspard, Kevin, Louisiana Transportation Research Center, United States. Federal Highway Administration, US Transportation Collection, Soils are normally dried in either a convection oven or stove. Inspections of field and laboratory moisture content testing indicated that the typical drying durations for a convection oven and stove were, 24 hours and 60 minutes, respectively. The objectives of this study were to determine the accuracy and soil drying duration of microwave ovens. This was accomplished by testing soils with and without additives. The soils were tested with a convection oven, computer controlled microwave oven, standard microwave oven, and stove. The convection oven was considered to produce the true moisture content and was, therefore, used as a basis for comparison for the results of the other devices. Based on appraisals of the results, the standard microwave oven is the most feasible device to use in drying soils., 759

2002, PDF, Tech Report, LTRC Project No. 99-3GT, State Project No. 736-99-0893, Drying, Soils, Microwaves, Ovens, Moisture content, Time duration, Accuracy, Drying soils, Louisiana, United States, Louisiana Transportation Research Center, Gaspard, Kevin, Louisiana Transportation Research Center, Louisiana. Dept. of Transportation and Development, US Transportation Collection, Soils are normally dried in either a convection oven or stove. Inspections of field and laboratory moisture content testing indicated that the typical drying durations for a convection oven and stove were, 24 hours and 60 minutes, respectively. The objectives of this study were to determine the accuracy and soil drying duration of microwave ovens. This was accomplished by testing soils with and without additives. The soils were tested with a convection oven (CO), computer controlled microwave oven (CMWO), standard microwave oven (SMWO), and stove. The convection oven was considered to produce the true moisture content and was, therefore, used as a basis for comparison for the results of the other devices. Based on appraisals of the results, the standard microwave oven is the most feasible device to use in drying soils.

The technical guide discusses the microwave cooking oven, the areas where leakage could exist from such devices and certain precautions to take for safe operation. Also outlined in the guide is a visual inspection check list to detect those faults that do occur which could make the oven potentially hazardous to the health of personnel and a suggested inventory list. (Author)

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Microwave-assisted extraction (MAE) treatments seem to be a promising sample preparation strategy to isolate nanomaterials (NMs) from environmental samples prior to single particle inductively coupled plasma mass (spICP-MS) determination. Nevertheless, because previous studies make use of domestic microwave ovens (DMOs), several shortcomings arise that compromise the analysis such as lack of control of experimental variables, limited operating conditions, and uncontrolled sample heating leading to irreproducibility issues. The goal of this work is to adapt previously developed MAE treatments for soil and air filters with the DMO apparatus to state-of-the-art scientific microwave ovens (SMOs) in order to standardize current analytical protocols for NM characterization. Results show that, by working with an SMO, non-labile metallic NMs (Pt-AuNPs) are quantitively extracted from soil and air filter samples unaltered in 10 min and 6 min, respectively, at 1200 W by using 10 mL of NaOH 0.1 M solution. The use of a SMO system allows improving accuracy (above 10% of the particle recovery), precision (above 5% of the RSD) and sample throughput (above 4-fold) when compared to the DMO ones. According to these findings, MAE seems to be a powerful strategy for routine analysis of non-labile NMs in environmental samples.

One type of trash fish that has potential in the waters of West Sumatra is peperek fish, but most of it is still not used. To increase the economic value of the peperek fish, one of them can be processed into fish meal. The problem that is often encountered is the quality of fishmeal that is not uniform and does not meet SNI Number 2715: 2013. This study aims to determine the differences in yield of peperek flour and quality of peperek fish meal processed using conventional pans, pressure cookers and microwave ovens. The research began with a study of the availability of peperek fish and continued with the manufacture of fish meal. Furthermore, an analysis of the fish meal obtained was carried out. The results showed that peperek fish accounted for 58.82% of the total trash fish. The yields of trash fish meal obtained from the use of conventional pans, pressure cookers and microwave ovens were 19.04%, 20.04% and 22.03%, respectively. The chemical analysis results of peperek fish meal were also obtained successively from the three treatments, namely the moisture content of 9.03%, 8.08% and 7.02%; ash content 5.68%, 5.46% and 6.16%; protein content of 71.35%, 69.88% and 68.80%; fat content 14.61%, 14.22% and 17.09%. The results showed that the use of a microwave oven could produce peperek fish meal with the highest yield with a slightly lower protein content compared to other boiling methods, but still included in A quality fish meal based on SNI Number 2715: 2013.

One type of trash fish that has potential in the waters of West Sumatra is peperek fish, but most of it is still not used. To increase the economic value of the peperek fish, one of them can be processed into fish meal. The problem that is often encountered is the quality of fishmeal that is not uniform and does not meet SNI Number 2715: 2013. This study aims to determine the differences in yield of peperek flour and quality of peperek fish meal processed using conventional pans, pressure cookers and microwave ovens. The research began with a study of the availability of peperek fish and continued with the manufacture of fish meal. Furthermore, an analysis of the fish meal obtained was carried out. The results showed that peperek fish accounted for 58.82% of the total trash fish. The yields of trash fish meal obtained from the use of conventional pans, pressure cookers and microwave ovens were 19.04%, 20.04% and 22.03%, respectively. The chemical analysis results of peperek fish meal were also obtained successively from the three treatments, namely the moisture content of 9.03%, 8.08% and 7.02%; ash content 5.68%, 5.46% and 6.16%; protein content of 71.35%, 69.88% and 68.80%; fat content 14.61%, 14.22% and 17.09%. The results showed that the use of a microwave oven could produce peperek fish meal with the highest yield with a slightly lower protein content compared to other boiling methods, but still included in A quality fish meal based on SNI Number 2715: 2013.

One type of trash fish that has potential in the waters of West Sumatra is peperek fish, but most of it is still not used. To increase the economic value of the peperek fish, one of them can be processed into fish meal. The problem that is often encountered is the quality of fishmeal that is not uniform and does not meet SNI Number 2715: 2013. This study aims to determine the differences in yield of peperek flour and quality of peperek fish meal processed using conventional pans, pressure cookers and microwave ovens. The research began with a study of the availability of peperek fish and continued with the manufacture of fish meal. Furthermore, an analysis of the fish meal obtained was carried out. The results showed that peperek fish accounted for 58.82% of the total trash fish. The yields of trash fish meal obtained from the use of conventional pans, pressure cookers and microwave ovens were 19.04%, 20.04% and 22.03%, respectively. The chemical analysis results of peperek fish meal were also obtained successively from the three treatments, namely the moisture content of 9.03%, 8.08% and 7.02%; ash content 5.68%, 5.46% and 6.16%; protein content of 71.35%, 69.88% and 68.80%; fat content 14.61%, 14.22% and 17.09%. The results showed that the use of a microwave oven could produce peperek fish meal with the highest yield with a slightly lower protein content compared to other boiling methods, but still included in A quality fish meal based on SNI Number 2715: 2013.

One type of trash fish that has potential in the waters of West Sumatra is peperek fish, but most of it is still not used. To increase the economic value of the peperek fish, one of them can be processed into fish meal. The problem that is often encountered is the quality of fishmeal that is not uniform and does not meet SNI Number 2715: 2013. This study aims to determine the differences in yield of peperek flour and quality of peperek fish meal processed using conventional pans, pressure cookers and microwave ovens. The research began with a study of the availability of peperek fish and continued with the manufacture of fish meal. Furthermore, an analysis of the fish meal obtained was carried out. The results showed that peperek fish accounted for 58.82% of the total trash fish. The yields of trash fish meal obtained from the use of conventional pans, pressure cookers and microwave ovens were 19.04%, 20.04% and 22.03%, respectively. The chemical analysis results of peperek fish meal were also obtained successively from the three treatments, namely the moisture content of 9.03%, 8.08% and 7.02%; ash content 5.68%, 5.46% and 6.16%; protein content of 71.35%, 69.88% and 68.80%; fat content 14.61%, 14.22% and 17.09%. The results showed that the use of a microwave oven could produce peperek fish meal with the highest yield with a slightly lower protein content compared to other boiling methods, but still included in A quality fish meal based on SNI Number 2715: 2013.

[EN] Microwave technology has come a long way from the sixties when the first microwave ovens were developed. This first generation of microwave ovens uses only microwaves to heat the substrate and with an efficiency of around 63% in converting electrical energy to microwaves, this means 37% of the electric energy is lost as heat. The first improvement to this system “second generation” is using hybrid heating with both microwaves and hot air. The hot air in this case is simply the air used to cool the magnetron and transformers that is blown into the microwave cavity. The 37% of lost energy can thus be reused. The first role of the hot air current is to remove moisture from the cavity to avoid condensation on the (cold) cavity walls. The second role is to insulate the hot product from the cold environment and prevent energy loss. The third role is increasing evaporation speed; this decreases drying time and can also keep the drying temperature low through evaporative cooling. Low drying temperatures are favored in many processes especially with food as it delivers a superior dry product.The “third generation” utilizes an additional heat exchange to further increase the system’s efficiency. The hot (wet) exhaust air is not fully saturated yet so it can be used to preheat the substrate before it enters the microwave cavity. A good example is thawing and preheating frozen starting material. If water cooled magnetrons are used, the hot air is replaced by hot water instead for the heat exchange. Microwave processes are generally much faster resulting in smaller machines and reduced operational area. When designing a microwave process all these factors need to be taken into account to result in the cheapest and most robust process. As heat exchange generally takes a long time, it should only be done to a degree that it does not slow down the microwave process.

Микроволновые печи как электроприборы нового поколения внесли определенные изменения в обычные традиционные приемы тепловой обработки пищевых продуктов. Однако проблема влияния электромагнитного излучения бытовых приборов на здоровье человека изучена не до конца. В данном исследовании, во - первых, рассмотрена история создания микроволновой печи, во - вторых, описано устройство и принцип работы СВЧ - печи, в- третьих, указаны факторы положительного и отрицательного влияния электромагнитного поля микроволновых печей на организм человека, в- четвёртых, представлены результаты экспериментов, дающих ясное представление об отрицательном влиянии микроволн на развитие растений. В проекте сформулированы правила безопасного использования СВЧ-печей. Исследование показало, что в микроволновой печи образуется “мертвая вода”, которая не содержит питательных веществ и замедляет процесс проращивания семян и рост растений, качество приготовленных продуктов в микроволновых печах существенно отличается от качества пищи, приготовленной на газовой плите. В ходе экспериментов установлено: электромагнитные микроволны приносят большой вред здоровью человека, поэтому при использовании микроволновой печи необходимо выполнять все инструкции и следить за сроком ее эксплуатации., Microwave ovens as electrical appliances of the new generation have made certain changes to conventional traditional methods of cooking food. However, the problem of the effect of electromagnetic radiation from household appliances on human health has not been thoroughly studied. In this study, firstly, the history of the microwave oven is considered, secondly, the device and the operating principle of the microwave oven are described; thirdly, the factors of the positive and negative influence of the electromagnetic field of microwave ovens on the human body are indicated; the fourth, the results of experiments that give a clear idea of the negative effect of microwaves on the development of plants. The draft rules for the safe use of microwave ovens. The study showed that in the microwave oven, "dead water" is formed, which does not contain nutrients and slows the germination of seeds and the growth of plants, the quality of cooked products in microwave ovens is significantly different from the quality of food prepared on a gas stove. During the experiments it was established: electromagnetic microwaves cause great harm to human health, therefore, when using a microwave oven, it is necessary to follow all instructions and monitor the period of its operation.

This thesis investigates the interference potential of microwave ovens to Bluetooth data communication. Interference experiments are conducted in the CWT's Bluetooth lab, using CSR™ (Cambridge Silicone Radio) Bluetooth radios and a Tektronics™ Protocol Analyzer to record packet transmissions between the master and slave units. A novel, "quasi-real time" spectral measurement concept is developed to take radio frequency measurements. A LabView program enables a spectrum analyzer to download oven spectral data onto a computer via the instrument's serial port. From this data, three-dimensional plots of microwave radiated power levels versus ISM band frequencies over time periods are produced for different microwave ovens. These plots are compared with the results of interference experiments to explain Bluetooth packet errors. In addition to causing packet errors, emitted oven power levels at certain frequencies are sometimes strong enough to cause data packets to be lost (dropped) as they are transmitted over the air. This is a major problem since the Protocol Analyzer does not "see" these packets and cannot record the transmissions during an experiment. These lost packets can be accounted for if the frequency hopping scheme of the communicating Bluetooth devices is know prior to data transmission. Bluetooth's Frequency Hop Scheme is coded in Matlab for the purpose of predicting a data transmission's hopping sequence. The lost packets on each Bluetooth channel are counted by subtracting the Analyzer's recorded number of data transmissions per channel from the total number of transmissions per channel predicted by Matlab. A method is devised to calibrate the Bluetooth receiver and the spectrum analyzer is used to measure the received power level of Bluetooth signals on a particular frequency (channel). The number of packet errors on a channel is determined from the channel's C/I (carrier-to-interference ratio). If a channel's C/I level falls below the calculated C/I thre

Microwave heating is an efficient way of heating compared to conventional industrial alternatives such as autoclaves, a type of pressure cooker commonly used for curing and sterilisation. One problem that limits the adoption of microwave ovens in industrial processes is uneven heating. This project aims to simplify industrial microwave oven development by constructing a simulation of microwave heating using the finite-difference time-domain (FDTD) method. This is a common accepted method for solving differential equations. Simulation tools can be used to efficiently create prototypes virtually which makes for a more efficient development process of customised microwave ovens.%The implementation is written in Python and uses Meep, an open source FDTD library for simulating electromagnetic fields. The end product produces a model of a physical system and simulates the interaction between microwaves and the target material. This interaction results in heating of the target material, which can be observed through an animated heat map. This heat map can then be compared to the video from a thermographic camera to determine the model's validity and accuracy. The results of this project confirms the validity of the approach but does not validate the accuracy of the simulation. The system requires further development in three areas: 2D simulations must be scaled to 3D, the simulations predictive ability must be validated and the simulated time span must be increased., Mikrovågsugnar är ett effektivt alternativ till konventionella lösningar för industriell uppvärmning, såsom autoklaver. autoklaver är en form av ugn som värmer under ökat tryck, ungefär som en tryckkokare, och används främst för härdning och sterilisering. Ojämn uppvärmning är en av de problemen som begränsar användning av mikrovågsugnar i industrin idag. Detta projekt försöker underlätta utveckling av industriella mikrovågsugnar genom att konstruera en simulering av mikrovågsuppvärmning genom finite-difference time-domain (FDTD) metoden. Detta är en vanligt förekommande metod för att lösa differentialekvationer. Med hjälp av simuleringsverktyg så kan digitala prototyper lätt skapas och testas, detta i sin tur leder till en effektivare utvecklingsprocess av specialdesignade microvågsugnar. Implementationen är skriven i python och använder Meep, ett FDTD-bibliotek för att simulera elektromagnetiska fält, med öppen källkod. Slutprodukten är en modell av ett fysiskt system där interaktionen mellan det elektriska fältet och materialet simulerats. Denna interaktion leder till uppvärmning av materialet, detta kan sedan observeras genom en animerad värmekarta. Denna kan sedan jämföras med en video från en termografisk kamera för att bestämma modellens giltighet och precision. Resultaten av detta projekt visar ett giltigt tillvägagångssätt, men verifierar inte giltigheten och precisionen av simuleringen. Systemet kräver vidareutveckling inom tre områden: Tvådimensionella simuleringar bör vara tredimensionella, simuleringens prediktiva förmåga måste valideras, samt att tidsspannet som simuleras bör ökas.

Microwave heating is an efficient way of heating compared to conventional industrial alternatives such as autoclaves, a type of pressure cooker commonly used for curing and sterilisation. One problem that limits the adoption of microwave ovens in industrial processes is uneven heating. This project aims to simplify industrial microwave oven development by constructing a simulation of microwave heating using the finite-difference time-domain (FDTD) method. This is a common accepted method for solving differential equations. Simulation tools can be used to efficiently create prototypes virtually which makes for a more efficient development process of customised microwave ovens.%The implementation is written in Python and uses Meep, an open source FDTD library for simulating electromagnetic fields. The end product produces a model of a physical system and simulates the interaction between microwaves and the target material. This interaction results in heating of the target material, which can be observed through an animated heat map. This heat map can then be compared to the video from a thermographic camera to determine the model's validity and accuracy. The results of this project confirms the validity of the approach but does not validate the accuracy of the simulation. The system requires further development in three areas: 2D simulations must be scaled to 3D, the simulations predictive ability must be validated and the simulated time span must be increased., Mikrovågsugnar är ett effektivt alternativ till konventionella lösningar för industriell uppvärmning, såsom autoklaver. autoklaver är en form av ugn som värmer under ökat tryck, ungefär som en tryckkokare, och används främst för härdning och sterilisering. Ojämn uppvärmning är en av de problemen som begränsar användning av mikrovågsugnar i industrin idag. Detta projekt försöker underlätta utveckling av industriella mikrovågsugnar genom att konstruera en simulering av mikrovågsuppvärmning genom finite-difference time-domain (FDTD) metoden. Detta är en vanligt förekommande metod för att lösa differentialekvationer. Med hjälp av simuleringsverktyg så kan digitala prototyper lätt skapas och testas, detta i sin tur leder till en effektivare utvecklingsprocess av specialdesignade microvågsugnar. Implementationen är skriven i python och använder Meep, ett FDTD-bibliotek för att simulera elektromagnetiska fält, med öppen källkod. Slutprodukten är en modell av ett fysiskt system där interaktionen mellan det elektriska fältet och materialet simulerats. Denna interaktion leder till uppvärmning av materialet, detta kan sedan observeras genom en animerad värmekarta. Denna kan sedan jämföras med en video från en termografisk kamera för att bestämma modellens giltighet och precision. Resultaten av detta projekt visar ett giltigt tillvägagångssätt, men verifierar inte giltigheten och precisionen av simuleringen. Systemet kräver vidareutveckling inom tre områden: Tvådimensionella simuleringar bör vara tredimensionella, simuleringens prediktiva förmåga måste valideras, samt att tidsspannet som simuleras bör ökas.