Gigahertz channel modeling for wireless sensor networks operating in LNG environment

LNG (Sıvılaştırılmış Doğal Gaz) doğal gazın -162 ºC’de soğutulması ile oluşturulan temiz, renksiz ve zehirsiz bir sıvıdır. Bu soğutma işlemi sayesinde doğal gazın hacmi 600 kat daha küçültülerek, LNG’nin depolanmasını ve taşınmasını kolaylaştırmaktadır. LNG' nin özgül ağırlığı basınç, sıcaklık ve karışıma göre değişir ve ortalama 1,0 kg/litre su ile mukayese edildiğinde, 0,46 kg/litre’ye eşittir. LNG’nin özgül ağırlığının düşük olması elektromanyetik dalgaların yayılımı ve TDA (Telsiz Duyarga Ağları)’nın haberleşebilmesi için bir avantajdır. Ayrıca bu çalışmada TDA’lar için LNG yol kaybı, yansıma etkisi ve BHO (Bit Hata Oranı)’a ya göre LNG ortamı analiz edilip, modellenmiştir. Yayılım karakteristikleri teorik yaklaşım ile incelenmiştir. Teorik analizler ve simülasyon sonuçları 10 GHz – 13 GHz bant aralığında, 10 metre civarı bir kablosuz haberleşme olacağını ispatlamaktadır.LNG (Liquefied Natural Gas) is a clear, colorless and non-toxic liquid which forms when natural gas is cooled to -162 ºC. The cooling process shrinks the volume of the gas 600 times, by this way making LNG easier and safer to store and ship. The density of LNG is around 0.46 kg/liter, depending on pressure, temperature, and composition, compared to water at 1.0 kg/liter. The lesser density of LNG is also an advantage for the propagation of the electromagnetic waves and communication of WSN (Wireless Sensor Networks) in LNG medium. Then here in this work LNG has analyzed according to path loss, multipath effect and providing an evaluation about the Bit Error Rate (BER) of the modelled channel depending on the LNG medium for WSNs. The propagation characteristics are investigated using a theoretical approach. The theoretical analysis and the simulation results prove the feasibility of wireless communication about 10 m range in the 10 GHz – 13 GHz band range in LNG medium

Signals in the Soil: An Introduction to Wireless Underground Communications

In this chapter, wireless underground (UG) communications are introduced. A detailed overview of WUC is given. A comprehensive review of research challenges in WUC is presented. The evolution of underground wireless is also discussed. Moreover, different component of UG communications is wireless. The WUC system architecture is explained with a detailed discussion of the anatomy of an underground mote. The examples of UG wireless communication systems are explored. Furthermore, the differences of UG wireless and over-the-air wireless are debated. Different types of wireless underground channel (e.g., In-Soil, Soil-to-Air, and Air-to-Soil) are reported as well

Terahertz Channel Modeling of Underground Sensor Networks in Oil Reservoirs

IEEE Global Communications Conference (GLOBECOM) -- DEC 03-07, 2012 -- Anaheim, CAWOS: 000322375100088Future enhanced oil recovery technology requires wireless sensor networks to effectively operate in underground oil reservoirs. In this case, the millimeter scale sensor nodes with the antennas at the same scale have to be deployed in the confined underground oil reservoir fractures. This necessitates the sensor nodes to be operating in the THz frequency range. In this paper, the propagation based on electromagnetic (EM) waves in the Terahertz band (0.1-120.0 THz) through a crude oil/water mixture and soil medium is analyzed in order to explore its applicability in underground oil reservoir assessments. The developed model evaluates the total path loss and the absorption loss that an EM wave experiences when propagating through the crude oil/water mixture and soil medium. Our results show that sensors can communicate successfully for distances up to 1 centimeter and we have determined the existence of two transmission bands, in which the path loss is below 100 dB. Among those, the frequency window, which provides best performance, determined as 70 to 85 THz. Different path and absorption loss schemes considered, which suggests that the 70 to 85 THz band is suitable for sensor communications in a medium of crude oil/water mixture and soil.IEEE, IEEE Commun So

Desenvolvimento de metodologias e dispositivos analíticos com deteção ótica para a indústria agroalimentar

Tese de doutoramento, Química (Química Física), Universidade de Lisboa, Faculdade de Ciências, 2016A indústria agroalimentar encontra-se em grande expansão e a sua monotorização é uma inevitabilidade mais que evidente. Com imposições ditadas por regulamentações ou pelo mercado, existe uma necessidade constante na implementação de sistemas de qualidade fiáveis, com tempos de resposta adequados e se possível de baixo custo. Esta necessidade, é o motor para o aparecimento de novas técnicas e equipamentos miniaturizados com vista à quantificação e deteção de compostos químicos e biológicos de interesse neste mercado. Neste contexto esta dissertação de doutoramento inserido no meio empresarial visou o estudo e desenvolvimento de sensores analíticos miniaturizados, para monotorização de diferentes parâmetros na indústria agroalimentar. O trabalho desenvolvido pode ser resumido em três grandes temas: contribuição para o desenvolvimento de uma plataforma para a construção de biossensores óticos; otimização de um equipamento e respetivo imunoensaio miniaturizado para a deteção de Ocratoxina A e desenvolvimento de sistemas analíticos para a quantificação de pH e azoto assimilável em vinho. Perspetivando a construção de uma plataforma de biossensores óticos, com todos os reagentes imobilizados, efetuou-se o estudo da modificação de superfícies (ITO e Au) recorrendo a polielectrólitos funcionalizados com ferroceno para a mediação da reação de eletroquimioluminescência do sistema luminol/H2O2. A mediação por diferentes derivados de ferroceno foi demonstrada em solução, e otimizada tendo em conta determinados fatores tais como pH, força iónica, concentração de reagentes (razão luminol/ferroceno) e método de perturbação eletroquímica no processo de eletroquimioluminescência. Sintetizou-se um polieletrólito catiónico funcionalizado com o grupo funcional ferroceno, tendo a sua adsorção electroestática sido avaliada em ITO e ouro previamente modificado com uma monocamada de 3-mercaptopropanosulfonato. A modificação dos elétrodos com recurso ao processo de montagem de camada por camada foi estudada, bem como a sua estabilidade a diferentes pH. Os elétrodos modificados aparentam uma elevada estabilidade eletroquímica quando avaliados em meios acídicos em oposição ao observado quando perturbados em soluções básicas, ideais para a intensificação do sinal ótico. No âmbito da participação no projeto europeu “Demotox” desenvolveu-se um protótipo pré-industrial para a deteção de Ocratoxina A (OTA) em cereais e vinho, recorrendo a um ensaio imunoenzimático em suporte sólido, baseado no princípio da interação específica entre anticorpo e antigénio (OTA). A miniaturização e alteração do formato do imunoensaio de competitivo indireto para competitivo direto bem como a otimização efetuada permitiu diminuir o tempo de ensaio, o número de passos no processo de deteção bem como revelar-se eficiente para a deteção de OTA em vinho no limite legal (2 ng/mL). A validação do equipamento, como sistema analítico semi-quantitativo de resposta binária (sim/não; contaminado/não-contaminado) foi realizado de acordo com as normas europeias em vigor, para cereais de alimentação animal, apresentando resultados bastante satisfatórios e passiveis de serem utilizados para o limite legal estabelecido 250 ppb de OTA. No terceiro tema abordado procedeu-se à construção de um elétrodo de pH de estado sólido e ao desenvolvimento de técnicas para a quantificação de azoto assimilável no vinho. A construção de um elétrodo de pH de estado sólido baseou-se na deposição eletroquímica de óxidos de irídio. A otimização do método de crescimento eletroquímico (potenciodinâmico e galvanoestático) foi efetuado contemplando o tempo de resposta e respetiva estabilidade dos depósitos obtidos, em soluções de diferentes pH. A resposta otimizada revelou um comportamento super-Nernstinian e boa linearidade com o pH em soluções tampão. O sinal obtido em amostras reais, vinho, apresenta uma elevada interferência de compostos redox presentes. Tal interferência foi minimizada pela deposição adicional de membranas de polifenol ou nafion, sem ser no entanto totalmente colmatada, estando em aberto a sua otimização. Para a determinação de iões amónio construiu-se um elétrodo seletivo de iões amónio (ISE) tendo sido avaliados vários parâmetros na sua construção, tais como: número de camadas da membrana seletiva, a presença e natureza de um condutor misto iónico/eletrónico. O elétrodo demonstrou excelente desempenho em solução tampão em oposição com o observado em amostras reais, devido à presença de uma elevada concentração de iões potássio no vinho. Com base nas propriedades de fluorescência de emissão de isoindolos provenientes da reação de o-ftaldeído, um nucleófilo e NH4 + ou α-aminoácidos, e utilizando como base a plataforma de medida Enosense® criada pela Lumisense,Lda desenvolveram-se dois métodos de medida, um para a determinação de iões amónio e outro para a determinação de aminoácidos em amostras de vinho.The agrifood industry is in expansion and its monitoring is an inevitability more than evident. With impositions dictated simultaneously by legal regulations and market, there is a constant need for the implementation of reliable control quality systems, with adequate response times and whenever possible with low cost. This need, is the drive for the development of new miniaturized analytical techniques and equipments aimed for the quantification and detection of chemical and biological compounds of interest in this market. In this context this doctoral dissertation aimed at the study and development of miniaturized analytical sensors for monitoring different parameters in the agribusiness industry. The work can be subdivided into three main themes: contribution to the development of a platform for the construction of optical biosensors, optimization of an equipment and corresponding miniaturized immunoassay for the detection of Ochratoxin A and development of analytical systems for the measurement of pH and yeast assimilable nitrogen in wine. Aiming at the construction of a platform for optical biosensors, with all the reagents immobilized on an electrode, a study was conducted on surface modification (IndiumTin Oxide (ITO) and Au) by ferrocene functionalized polyelectrolytes for the mediation of the electrochemiluminescence reaction between luminol and H2O2. The mediation of distinct ferrocenes derivatives was demonstrated in solution, and the experimental conditions were optimized considering the pH, ionic strength, concentration of reagents (molar fraction luminol/ferrocene) and the applied electrochemical method in the ECL process. The electrostatic adsorption of the synthetized ferrocene functionalized cationic polyelectrolyte was evaluated in ITO and gold surfaces, where the latter was previously modified with a self-assembled monolayer of (3-mercaptopropyl)sulfonate monolayer. The modification of the electrode surfaces with thin films, formed via the adsorption of a layer-by-layer assembly of charged polyelectrolytes, revealed a high electrochemical stability in acidic media as opposed to the observed when studied in basic solutions, which are ideal for the intensification of the optical signal. In the context of Lumisense participation in a European project "Demotox", a preindustrial prototype was developed for the detection of Ochratoxin A (OTA) in cereals and wine, by means of an enzyme-linked immunosorbent assay in solid support, based on the principle of specific interaction between antibody and antigen (OTA). The miniaturization and the format change of the immunoassay from an indirect competitive to a direct competitive immunoassay, as well as its performance optimization, allowed to decrease the total assay time, the number of involved steps, and also enabled OTA detection in wine at the legal limit (2 ng/mL). The equipment validation, as an analytical semi-quantitative system based on a binary response (yes/no; contaminated/non-contaminated) was performed in accordance to European standards for cereals used for animal feed, presenting very satisfactory results and allow it to be used for the legal limit established for OTA of 250 ppb. The third theme concerned the construction of a solid state pH probe, as well as the development of optical methods for the quantification of yeast assimilable nitrogen in wine. The pH probe was constructed based on the electrochemical deposition of iridium oxides. The optimization of the electrochemical growth methods (potentiodynamic and galvanostatic) was performed by considering the stability and response time of the obtained deposits, at solutions with different pH. The optimized answer showed super-Nernstinan response with good linearity in buffer solutions. The signal obtained in real wine samples reveals a high interference of the redox compounds present in wine matrix. Such interference was slightly minimized by adding a membrane of polyphenol or nafion, without being totally surpassed, opening space for further optimization. An ion solid state selective electrode probe was developed for the determination of ammonium ions in wine. A number of parameters have been optimized during the electrode construction, such as number of layers of the selective membrane, the presence and nature of a ionic/electronic conductive layer. The probe demonstrated excellent performance in buffer solution in opposition with the observed in real samples, due to the presence of a high concentration of potassium ions in the wine. Based on the fluorescence properties of the isoindole products, formed during the reaction of o-phthalaldehyde, a nucleophile and NH4 + or α-amino acids, and using Enosense® platform, developed by Lumisense Lda for optical detection, two analytical methodologies were successfully developed, one for the determination of ammonia ions and another for the determination of amino acids in wine samples. The agrifood industry is in expansion and its monitoring is an inevitability more than evident. With impositions dictated simultaneously by legal regulations and market, there is a constant need for the implementation of reliable control quality systems, with adequate response times and whenever possible with low cost. This need, is the drive for the development of new miniaturized analytical techniques and equipments aimed for the quantification and detection of chemical and biological compounds of interest in this market. In this context this doctoral dissertation aimed at the study and development of miniaturized analytical sensors for monitoring different parameters in the agribusiness industry. The work can be subdivided into three main themes: contribution to the development of a platform for the construction of optical biosensors, optimization of an equipment and corresponding miniaturized immunoassay for the detection of Ochratoxin A and development of analytical systems for the measurement of pH and yeast assimilable nitrogen in wine. Aiming at the construction of a platform for optical biosensors, with all the reagents immobilized on an electrode, a study was conducted on surface modification (IndiumTin Oxide (ITO) and Au) by ferrocene functionalized polyelectrolytes for the mediation of the electrochemiluminescence reaction between luminol and H2O2. The mediation of distinct ferrocenes derivatives was demonstrated in solution, and the experimental conditions were optimized considering the pH, ionic strength, concentration of reagents (molar fraction luminol/ferrocene) and the applied electrochemical method in the ECL process. The electrostatic adsorption of the synthetized ferrocene functionalized cationic polyelectrolyte was evaluated in ITO and gold surfaces, where the latter was previously modified with a self-assembled monolayer of (3-mercaptopropyl)sulfonate monolayer. The modification of the electrode surfaces with thin films, formed via the adsorption of a layer-by-layer assembly of charged polyelectrolytes, revealed a high electrochemical stability in acidic media as opposed to the observed when studied in basic solutions, which are ideal for the intensification of the optical signal. In the context of Lumisense participation in a European project "Demotox", a preindustrial prototype was developed for the detection of Ochratoxin A (OTA) in cereals and wine, by means of an enzyme-linked immunosorbent assay in solid support, based on the principle of specific interaction between antibody and antigen (OTA). The miniaturization and the format change of the immunoassay from an indirect competitive to a direct competitive immunoassay, as well as its performance optimization, allowed to decrease the total assay time, the number of involved steps, and also enabled OTA detection in wine at the legal limit (2 ng/mL). The equipment validation, as an analytical semi-quantitative system based on a binary response (yes/no; contaminated/non-contaminated) was performed in accordance to European standards for cereals used for animal feed, presenting very satisfactory results and allow it to be used for the legal limit established for OTA of 250 ppb. The third theme concerned the construction of a solid state pH probe, as well as the development of optical methods for the quantification of yeast assimilable nitrogen in wine. The pH probe was constructed based on the electrochemical deposition of iridium oxides. The optimization of the electrochemical growth methods (potentiodynamic and galvanostatic) was performed by considering the stability and response time of the obtained deposits, at solutions with different pH. The optimized answer showed super-Nernstinan response with good linearity in buffer solutions. The signal obtained in real wine samples reveals a high interference of the redox compounds present in wine matrix. Such interference was slightly minimized by adding a membrane of polyphenol or nafion, without being totally surpassed, opening space for further optimization. An ion solid state selective electrode probe was developed for the determination of ammonium ions in wine. A number of parameters have been optimized during the electrode construction, such as number of layers of the selective membrane, the presence and nature of a ionic/electronic conductive layer. The probe demonstrated excellent performance in buffer solution in opposition with the observed in real samples, due to the presence of a high concentration of potassium ions in the wine. Based on the fluorescence properties of the isoindole products, formed during the reaction of o-phthalaldehyde, a nucleophile and NH4 + or α-amino acids, and using Enosense® platform, developed by Lumisense Lda for optical detection, two analytical methodologies were successfully developed, one for the determination of ammonia ions and another for the determination of amino acids in wine samples