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Microwave Measurements (microwave + measurement)
Selected AbstractsFREE-SPACE MICROWAVE MEASUREMENT of LOW MOISTURE CONTENT IN POWDERED FOODSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2000RAM M. NARAYANAN A free-space microwave transmission technique has been developed and tested for rapid inline noninvasive measurement of the moisture content of various types of food powders. the basis of this technique is the relation between the attenuation of X-band microwave radiation through a sample of the food powder to its moisture content by weight. Since food powders generally lose their utility and desirable properties, such as flowability and resistance to spoilage, at lower levels of moisture content, typically 3,7%, special techniques must be developed in order to accurately characterize the moisture content at these low levels. One such technique is to use frequency averaging to enhance the accuracy of the measurements to avoid multiple reflection effects prevalent in low-loss low-moisture attenuation measurements. This technique was implemented in the moisture content estimation. Overall accuracies in moisture content estimation are generally less than 1%, although in some cases, accuracies are in the vicinity of 5%. [source] EFFECT OF GLYCEROL ON PHYSICAL PROPERTIES OF CASSAVA STARCH FILMSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2010P. BERGO ABSTRACT In this work, the effect of glycerol on the physical properties of edible films were identified by X-ray diffraction (XRD), differential scanning calorimetry (DSC), infrared (FTIR) and microwave spectroscopy. According to XRD diffractograms, films with 0 and 15% glycerol displayed an amorphous character, and a tendency to semicrystallization, for films with 30% and 45% glycerol. From DSC thermograms, the glass transition (Tg) of the films decreased with glycerol content. However, two Tgs were observed for samples with 30% and 45% glycerol, due to a phase separation. The intensity and positions of the peaks in FTIR fingerprint region presented slight variations due to new interactions arising between glycerol and biopolymer. Microwave measurements were sensitive to moisture content in the films, due to hydrophilic nature of the glycerol. The effect of plasticizer plays, then, an important rule on the physical and functional properties of these films, for applications in food technology. PRACTICAL APPLICATIONS Edible and/or biodegradable films are thin materials used mainly in food recovering, food packaging and other applications, in substitution of the films obtained by synthetic ways. In view of these applications, these films must satisfy some of the exigencies in order to increase the food shelf-life, or in other words, they must be flexible, transparent, resistant to some gases such as oxygen, as well as resistant to water vapor. The addition of plasticizers alters the functional properties of the films. Thus, the physical characterization of these films becomes fundamental in order to increase their potential use in industry. [source] A novel method of detecting cervical cancer using microwavesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2008Anil Lonappan Abstract This article communicates a new method of detecting cervical cancer based on the measurement of the dielectric properties of smear at microwave frequencies. The microwave measurements were performed by rectangular cavity perturbation in the S-band of microwave frequency with the smear samples from healthy persons as well as from cancerous patients. It is observed an appreciable change in the dielectric properties of cancerous samples with the normal healthy samples and these measurements were in good agreement with clinical analysis. This measurement technique is simple and the collection of smear is painless and nonsurgical in nature. The results show a new method of diagnosing cervical cancer using microwave measurement without any surgical procedures and suggest an alternative to Papanikolaou test or Papanicolaou test. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1552,1554, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23433 [source] Applications of artificial neural networks to RF and microwave measurementsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 1 2002Jeffrey A. Jargon Abstract This article describes how artificial neural networks (ANNs) can be used to benefit a number of RF and microwave measurement areas including vector network analysis (VNA). We apply ANNs to model a variety of on-wafer and coaxial VNA calibrations, including open-short-load-thru (OSLT) and line-reflect-match (LRM), and assess the accuracy of the calibrations using these ANN-modeled standards. We find that the ANN models compare favorably to benchmark calibrations throughout the frequencies they were trained for. We summarize other current applications of ANNs, including the determination of permittivities of liquids from the reflection coefficient measurements of an open-ended coaxial probe and the determination of moisture content of wheat from free-space transmission coefficient measurements. We also discuss some potential applications of ANN models related to power measurements, material characterization, and the comparison of nonlinear vector network analyzers. © 2002 John Wiley & Sons, Inc. Int J RF and Microwave CAE 12: 3,24, 2002. [source] Fabrication of a novel micron scale Y-structure-based chiral metamaterial: Simulation and experimental analysis of its chiral and negative index properties in the terahertz and microwave regimesMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2007Nantakan Wongkasem Abstract In this report, we describe the fabrication of a chiral metamaterial based on a periodic array of Y-shaped Al structures on a dielectric Mylar substrate. The unit cell dimensions of the Y-structure are ,100 ,m on a side with 8 ,m linewidths. The fabricated Y-structure elements are characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Quantitative elemental analyses were carried out on both the Y-structure, comprised of Al and its oxide, as well as adjacent regions of the underlying mylar substrate using the energy dispersive X-ray spectroscopy (EDS) capability of the SEM. Finite-Difference Time-Domain (FDTD) calculations of the negative index of refraction for a 3D wedge of multiple layers of the 2D metamaterials showed that these metamaterials possess double negative (,,,,,) electromagnetic bulk properties at THz frequencies. The same negative index of refraction was determined for a wedge comprised of appropriately scaled larger Y-structures simulated in the microwave region. This double negative property was confirmed experimentally by microwave measurements on a 3D wedge comprised of stacked and registered Y-structure sheets. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source] | ||||||||||