33 research outputs found

    Current Advances in Internet of Underground Things

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    The latest developments in Internet of Underground Things are covered in this chapter. First, the IOUT Architecture is discussed followed by the explanation of the challenges being faced in this paradigm. Moreover, a comprehensive coverage of the different IOUT components is presented that includes communications, sensing, and system integration with the cloud. An in-depth coverage of the applications of the IOUT in various disciplines is also surveyed. These applications include areas such as decision agriculture, pipeline monitoring, border control, and oil wells

    Accuracy of soil moisture measurement by TDR technique

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    The influence of temperature on soil dielectric permittivity and the TDR determined soil moisture

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    Rozwa偶ano wp艂yw temperatury na przenikalno艣膰 dielektryczn膮 gleby oraz na powi膮zany z nim b艂膮d pomiaru wilgotno艣ci obj臋to艣ciowej gleby oznaczony metod膮 reflektometryczn膮. Badania przeprowadzono w warunkach laboratoryjnych na pr贸bkach gleby piaszczystej, pylastej i ilastej oraz w warunkach polowych na nasyconej wod膮 glebie torfowej. Stwierdzono, 偶e wp艂yw temperatury na przenikalno艣膰 dielektryczn膮 gleby, a wi臋c r贸wnie偶 na refiektometryczny pomiar wilgotno艣ci gleby, jest zale偶ny zar贸wno od wilgotno艣ci jak i uziarnienia (gatunku) gleby, To, czy wp艂yw temperatury powinien by膰 uwzgl臋dniony i korygowany, zale偶y od wymaganej dok艂adno艣ci pomiar贸w. W ekstremalnych warunkach, tzn. dla nasyconej gleby piaszczystej, ten b艂膮d jest na tyle du偶y, 偶e powinien by膰 uwzgl臋dniony, W oparciu o tr贸jfazowy model gleby zaproponowano korekt臋 wp艂ywu temperatury na odczyt miernika TDR wilgotno艣ci obj臋to艣ciowej gleby.The article discusses the influence of temperature on the soil dielectric constant and on the error of soil moisture determined by reflectometric (TDR) method.The measurements were performed in laboratory conditions on the samples of sand, silt and clay soils, as well as in field conditions on saturated pit soil. It was found that the temperature influences the soil dielectric constant and consequently the soil moisture values determined by reflec to metric method This influence depends on soil moisture and type. The correction of soil moisture readout from the TDR meter may significantly decrease the error of soil moisture determination. In extremal conditions, i.e. for saturated sand soil this error reaching 7% must be corrected. The temperature correction formulae of TDR determined soil moisture and the effect of its application were presented

    Techniki spektroskopii dielektrycznej w badaniu jako艣ci materia艂贸w i produkt贸w rolniczych

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    Spektroskopia dielektryczna opisuje w艂a艣ciwo艣ci dielektryczne pr贸bki materia艂u w funkcji cz臋stotliwo艣ci. Takimi materia艂ami mog膮 by膰 obiekty agrofizyczne, np. gleba, owoce, warzywa, p贸艂produkty i produkty przemys艂u spo偶ywczego, ziarno itp. Techniki spektroskopii dielektrycznej umo偶liwiaj膮 pomiar nieniszcz膮cy oraz nieinwazyjny obiekt贸w agrofizycznych daj膮c szybk膮 ocen臋 ich wilgotno艣ci oraz jako艣ci

    Frequency domain reflectometry as a selective method for soil moisture measurement

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    W niniejszej pracy zbadano wp艂yw zasolenia gleby na selektywno艣膰 pomiaru jej wilgotno艣ci wykonanego metod膮 reflektometrii cz臋stotliwo艣ciowej. W pracy podj臋to pr贸b臋 opracowania i oceny nowej sondy dwu-pr臋towej. W oparciu o zjawisko transformacji impedancji opracowano model sondy umo偶liwiaj膮cy pomiar widma do cz臋stotliwo艣ci 500 MHz. Metod膮 referencyjn膮 pomiaru wilgotno艣ci by艂 pomiar termograwimetryczny. Z pomiar贸w wynika, 偶e dla pasma powy偶ej 300 MHz zastosowana metoda pozwala na selektywny pomiar wilgotno艣ci gleby.The paper presents investigations of the influence of soil salinity on moisture measurements. The measurements were made by the (FDR) frequency domain reflectometry method. This method allows obtaining the frequency spectrum of complex dielectric permittivity when using the presented electrical model of the applied probe. Application of dielectric spectroscopy methods to analysis of results enables obtaining other information, besides moisture and salinity, about investigated soils. There is presented the use of a two-rod probe and its evaluation from the point of view of soil moisture selective measurements. An electrical model of the probe was formulated basing on the impedance transformation phenomenon in symmetrical waveguides. This model allows achieving 500 MHz frequency band unavailable till now for two-rod probes in commercial devices. Black earth soil type samples from Annopol were investigated. All measurements were taken with a vector network analyzer ZVCE produced by Rohde&Schwartz. The measured complex reflection coefficient S11 from the probe was used to obtain 10-500 MHz frequency spectrum of complex dielectric permittivity. The thermogravimetric measurement method of soil volumetric water content was used as the reference one. Five series of ten soil samples of different moisture and electrical conductivity values were analysed. The results show that the described FDR method allows measuring soil moisture selectively above 300 MHz

    Identification of errors of low soil water content measurements by TDR reflectometric sensors

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    W pracy podj臋to pr贸b臋 identyfikacji 藕r贸de艂 b艂臋du pomiaru ma艂ych warto艣ci wilgotno艣ci gleby sond膮 reflektometryczn膮 TDR, kt贸re powstaj膮 na skutek efektu splotu sygna艂贸w. Wykazano, 偶e wyb贸r medi贸w kalibracyjnych o warto艣ciach przenikalno艣ci elektrycznej bliskich dolnemu i g贸rnemu zakresowi pomiarowego przenikalno艣ci elektrycznej mierzonej gleby zmniejsza b艂膮d pomiaru tej wielko艣ci i w konsekwencji b艂膮d pomiaru wilgotno艣ci gleby oraz umo偶liwia u偶ycie sond TDR o r贸偶nych d艂ugo艣ciach pr臋t贸w.Reflectometric TDR sensors working in time domain (TDR - Time Domain Reflectometry) are successfully used for laboratory and field measurements of the soil bulk dielectric permittivity and, indirectly, the soil water content. Commonly applied methods for calibrating these sensors use two media, in which the respective parallel waveguides of the TDR sensor are inserted into: air - for low and water - for high values of dielectric permittivity. However, the variability range of the soil bulk dielectric permittivity is much smaller than the one associated with these calibration media. Application of air to calibration of short TDR sensors causes output waveform overlapping errors of the pulse reflected from the rods beginning with the pulses reflected from the rods open termination, which results in a relative time shift of these pulses. In the paper there is shown the way how to minimise these errors, called convolution effect errors, by application of other than air and water calibration media. The authors try to identify the error sources of low soil water content values measured by a TDR reflectometric sensor caused by the convolution effect. It is shown that the proper choice of calibration media having dielectric permittivity values close to low and high limits of the measurement range of the measured porous medium (soil) decreases the dielectric permittivity measurement error and, consequently, the measurement error of water content as well as enables application of variable length TDR sensors

    Frequency method for the measurement of the porous materials complex dielectric permittivity using probes of different length

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    Celem pracy jest por贸wnanie dw贸ch metod pomiaru zespolonej przenikalno艣ci dielektrycznej gleby. W pierwszej metodzie wykorzystywanej do pomiar贸w referencyjnych u偶yta zosta艂a sonda Open-Ended. W drugiej metodzie do pomiar贸w zosta艂y wykorzystane sondy dwupr臋towe o r贸偶nej d艂ugo艣ci, przy pomocy kt贸rych dokonywano pomiaru przenikalno艣ci dielektrycznej w tak dobranych cz臋stotliwo艣ciach, aby mo偶na je by艂o traktowa膰 jako elementy o parametrach skupionych. W pracy przedstawiono kalibracj臋 sond dwupr臋towych metod膮 u偶ywan膮 do kalibracji sond Open-Ended. Polega ona na pomiarach sond w stanach zwarcia, rozwarcia i po umieszczeniu ich w o艣rodku o znanych w艂a艣ciwo艣ciach dielektrycznych. Po kalibracji dokonano pomiar贸w parametr贸w odbiciowych na pr贸bkach trzech gleb w wybranych cz臋stotliwo艣ciach. Wszystkie pomiary wykonywane by艂y wektorowym analizatorem sieci pracuj膮cym w zakresie cz臋stotliwo艣ci 20 kHz + 8 GHz. Obiektami badanymi by艂y trzy gleby o r贸偶nym rozk艂adzie granulometrycznym oraz wilgotno艣ci. Ze wzgl臋du na specyfik臋 pomiaru w pracy przedstawiono analiz臋 dla jednej tylko gleby. Por贸wnanie wynik贸w pozwala s膮dzi膰, 偶e stosowane metody wykazuj膮 si臋 wysok膮 korelacj膮 wynik贸w w przypadku pomiar贸w obu sk艂adowych zespolonej przenikalno艣ci dielektrycznej.The main aim of the study is comparision of two measurement methods of the complex dielectric permittivity of soils. The first one used an Open-Ended probe and it was a reference method. The other one used two-rod probes of different length. These probes measured reflection parameters soils in selected frequencies that enabled to treat the probes as elements of lumped parameters. The study presents calibration of the two-rod probes using the method applied in Open-Ended probes. Il consists of measurements in shorted and open states as well as the measurement in a medium of known dielectric properties. All measurements were done using a vector network analyzer of the frequency range 20 kHz 8 GHz. Three soils of various texture and moisture were the analysed objects. Due to specificity of the measurement the paper presents the analysis for only one soil. The comparison of the measured data shows that the real and imaginary parts of the complex dielectric permittivity measured by both methods are highly correlated
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