Current Issue : January - March Volume : 2016 Issue Number : 1 Articles : 5 Articles
An iterative approach, based on the linear sampling method (LSM) and the contrast source inversion (CSI) method, is proposed to\nimprove the recovered images of multiple targets and targets with layered or continuous profile, including shape and distribution\nof electric properties. The difficulties in dealing with large targets or high contrast are partly overcome with this approach. Typical\ntargets studied in the literatures are chosen for simulations and comparison....
A novel wide stopband (WSB) low pass filter based on combination of defected ground structure (DGS), defected microstrip\nstructure (DMS), and compensated microstrip capacitors is proposed. Their excellent defected characteristics are verified through\nsimulation and measurements.Additionally to a sharp cutoff, the structure exhibits simple design and fabrication, very low insertion\nloss in the pass band of 0.3 dB and it achieves a wide rejection bandwidth with overall 20 dB attenuation from 1.5GHz up to 8.3GHz.\nThe compact low pass structure occupies an area of (0.40...
The research reported in this paper aims at developing means of Non Destructive testing (NDT) to\nincrease the line efficiency of pipe production in oil and natural gas pipe manufacturing plants\nusing the Standard Allowed Minutes (SAM) method. Existing line production stations encounter\ndifficulties in maintaining the recommended testing speed of smaller diameter pipe, due to limitations\nin the Visual Inspection (VI) station. We propose to implement one additional technique\nwhich will prevent the decline of line efficiency in a pipe production factory. The range of diameters\nidentified as a problem in this research is from 254 mm to 762 mm. Microwave techniques are\nexpected to improve the line efficiency by increasing the production of the plant. This happens as\na consequence of maintaining the production rates of the identified pipe diameters, so that they\nequal the production output of the larger pipe diameters. We analyze the velocity traveled by the\npipe through Radiographic Testing (RT) according to the VI output (production). The RT velocity\nis decreased for the diameters identified above, in order to maintain quality control and cover the\nshortcoming of the VI. The number of pipes produced is computed during shift hours of the factory\nand pipe lengths of the forming department are determined. We compare the output (production)\nof a series of NDT line stations with and without the microwave technique for the first of the three\npipe cases considered in this study, classified as perfect pipe (PP), repair pipe (RP) and scrap pipe\n(SP). The velocity of RT stations analyzed in the paper ranges from 50 mm/s for larger diameter\npipe, and decline to 16.667 mm/s for the identified diameters. The analytical calculations of line\noutput (production) and line efficiency demonstrate the solution of this velocity problem after the\nmicrowave technique is introduced. It demonstrates that an economical and precise methodology\nto extend the production capability of the pipe plant has been determined....
In the food industry, research into the characteristics of microwave-heated materials\nhas focused on dielectric properties. However, the lack of studies on microwave-absorbing\nproperties has hindered the application of microwave technology. The aim of the present\nstudy was to investigate the microwave-absorbing properties of rice starch. It should be\nnoted that this was the first time that the improved arch method was used to measure\nthe microwave reflection loss (RL) of the starch dispersion. The results showed that the\nmicrowave absorption of the liquid system corresponded to the classical quarter-wavelength\nresonator model. When the concentration of the native starch was increased from 1% to 30%,\nthe RL decreased from �´5.1 dB to �´1.2 dB at 2.45 GHz. Therefore, the absorption rate of\nmicrowave, �³ab, decreased from 69.1% to 24.1%. At 1.7 to 2.6 GHz, the interference effect\nof pregelatinization rice starch in an aqueous system on the microwave absorption properties\nbecame weak compared to native starch....
Microwave remote sensing is important for observing\nthe mass of ice hydrometeors. One of the main error\nsources of microwave ice mass retrievals is that approximations\naround the shape of the particles are unavoidable. One\ncommon approach to represent particles of irregular shape\nis the soft particle approximation (SPA). We show that it is\npossible to define a SPA that mimics mean optical particles of\navailable reference data over narrow frequency ranges, considering\na single observation technique at the time, but that\nSPA does not work in a broader context. Most critically, the\nrequired air fraction varies with frequency and application, as\nwell as with particle size. In addition, the air fraction matching\nestablished density parameterisations results in far too\nsoft particles, at least for frequencies above 90 GHz. That is,\nalternatives to SPA must be found.\nOne alternative was recently presented by Geer and\nBaordo (2014). They used a subset of the same reference data\nand simply selected as ââ?¬Å?shape modelââ?¬Â the particle type giving\nthe best overall agreement with observations. We present\na way to perform the same selection of a representative particle\nshape but without involving assumptions on particle size\ndistribution and actual ice mass contents. Only an assumption\non the occurrence frequency of different particle shapes\nis still required. Our analysis leads to the same selection of\nrepresentative shape as found by Geer and Baordo (2014).\nIn addition, we show that the selected particle shape has the\ndesired properties at higher frequencies as well as for radar\napplications.\nFinally, we demonstrate that in this context the assumption\non particle shape is likely less critical when using mass\nequivalent diameter to characterise particle size compared to\nusing maximum dimension, but a better understanding of the\nvariability of size distributions is required to fully characterise\nthe advantage.\nFurther advancements on these subjects are presently difficult\nto achieve due to a lack of reference data. One main\nproblem is that most available databases of pre calculated optical\nproperties assume completely random particle orientation,\nwhile for certain conditions a horizontal alignment is\nexpected. In addition, the only database covering frequencies\nabove 340 GHz has a poor representation of absorption\nas it is based on outdated refractive index data as well as\nonly covering particles having a maximum dimension below\n2mm and a single temperature....
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