100 research outputs found
Comparative study of mutual coupling on microstrip antennas for wireless local area network (WLAN) application
No full textThe increasing in interest of wearable antenna for military, sport, and medical applications may replace the uses of wired-communication network to wireless and wearable network. . In this paper, three shapes of the antennas which resonate at 2.4GHz and 5.2 GHz have been designed using jeans with the permittivity constant of 1.7 as the dielectric. The mutual coupling of the array antenna for the various shapes has been analyzed in H-plane and E-plane configuration respectively. The mutual coupling for the antenna in E-plane configuration has shown more sensitive toward the variation of distance between the elements, with compared to the elements in H-plane arrangement
Wearable textile antenna on electromagnetic band gap (EBG) for WLAN applications
No full textThis paper presents a new dual band wearable textile antenna for on body application, at 2.4 GHz and 5.2 GHz. The performance of the antenna is described with the integration of an electromagnetic band gap (EBG) structure. The antenna and EBG structure are made of jeans material which has a dielectric constant of 1.7, with the thickness of 1.2 mm and 0.025 loss tangent. The conductive component used in this paper is copper tape with thickness of 0.02 mm. The EBG array consists of 6 elements which are arranged in circular pattern surrounding the antenna patch. The effect of placing the EBG below the conventional antenna is studied and compared with the performance of the antenna alone. The gains of the antenna are improved by 63.7% and 121.4% at 2.4 GHz and 5.2 GHz respectively after integrating the EBG structure. At least 10 dB of backward radiation is reduced with the presence of the EBG structure. The integration of EBG with the conventional antenna has improved the antenna performance. The simulated and measured return loss, together with E-plane and H-plane polar pattern are presented in this paper for both conditions
A low profile switchable pattern directivity antenna using circular sectorized EBG
No full textIn this paper, a low profile patch antenna switchable radiation pattern diversity with total thickness of less than ?0/14 has been established.. The novel antenna structure is based on a conformal patch antenna operating in TM01 mode is integrated over an electromagnetic band gap (EBG) surface to provide a beam scanning antenna. The circular EBG elements are arranged in 6-sectors and the vias on each sector of the EBG are switched in and out to steer the
beam into that sectors. The reflection coefficients for the antenna when the vias are switched remain stable. The simulation and experimentation results have shown that the antenna power pattern directed toward the sector, without via or the middle of sectors, without via. Overall a flexible low profile beam steering antenna is demonstrated. The antenna is designed for wireless network application especially to improve the system performance in multipath propagation environment. Furthermore, the low profile antenna makes it suitable to be used in vehicular application
A technique of scan blindness elimination for planar phased array antenna using miniaturized EBG
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Werkwijze voor het behandelen van ammonia-houdend afvalwater
No full textTreatment of ammonia-comprising waste water comprises: (a) subjecting the waste water to a nitrification treatment using a nitrifying microorganism and adding oxygen, to give a solution comprising an oxidation product of ammonia, and (b) converting the oxidation product of ammonia into nitrogen using a denitrifying microorganism, use of bicarbonate-containing waste water, which is substantially stripped of bicarbonate by the supply of air, and maintaining the pH in the 1st step at \~7.2 by controlling the aeration, part of the ammonia present is converted into nitrite, and in the 2nd step the denitrifying microorganism uses the formed nitrite as oxidant for the remaining ammonia.Applied Science
Growth and metabolism of Anammox Bacteria
No full textThe anoxic ammonium oxidation (anammox) process is the conversion of nitrite and ammonium under anoxic conditions- to form dinitrogen gas. The process is performed by deep-branching Planctomycetes. The startup of the first full-scale anammox reactor in the world is described in Chapter 2. The described full scale reactor was a granular sludge reactor which was optimized for biomass retention. The reactor was scaled up directly from lab-scale to full-scale without the intermediate step of a pilot plant- and the step from lab-scale to full-scale took three years. In the first phase of the startup, quantification of the number of anammox bacteria, which were present in the reactor by quantitative polymerase chain reaction (Q-PCR) was a reliable indicator of growth of the anammox bacteria. The volumetric conversion of 10 kg N/m3/day is high compared to lab-scale systems. In Chapter 3, anammox bacteria were grown as free suspended (planktonic) cells. Even at a Sludge Retention Time (SRT) of 12 days (doubling time 8.3 days) stable operation was possible. The purity of the biomass was estimated to be 97.6%, which was the highest level of enrichment ever achieved for anammox reactors. The addition of hydroxylamine and the subsequent transient production of hydrazine can be regarded as a benchmark for the anammox process. In Chapter 4, the kinetics of the conversion were studied in detail for "Kuenenia stuttgartiensis". Hydrazine accumulated slightly after addition of hydroxylamine and remained low until near completion of the hydroxylamine. At that moment, the hydrazine level suddenly rose to ca. 100 μM, after which it gradually disappeared. The overall reaction was a disproportionation of hydroxylamine into ammonium and dinitrogen gas. The observed sudden accumulation of hydrazine could only be explained by assuming that hydrazine was an intermediate in this process. Two simple mathematical models, based on the continuous turn over of hydrazine during hydroxylamine conversion, were capable of quantitatively explaining the observed phenomena. The production of nitric oxide, another potential intermediate in the anammox process, was studied in combination with the emission of greenhouse gas nitrous oxide (N2O) in a full scale two reactor nitritation anammox process in Chapter 5. The NO and N2O emissions in the nitritation reactor were 0.2% and 1.7% of the nitrogen load respectively and 0.003% and 0.6% for the anammox reactor. The NO emission in the nitritation reactor was higher at higher aeration flows and NO seemed to be produced mainly in the period when the nitritation reactor was aerated. The N2O emission on the other hand seemed to be mainly produced during anoxic periods. Anammox bacteria have a unique cell plan consisting of several membrane-surrounded compartments. In the main compartment, the anammoxosome, the anammox catabolism is hypothesized to take place. Therefore, also the proton motive force is probably generated between the anammoxosome and the riboplasm by which the anammoxosome is surrounded. 31P nuclear magnetic resonance (NMR) spectroscopy was used to evaluate the pH difference over the anammoxosome membrane of "Kuenenia stuttgartiensis" in vivo in Chapter 6. Two compartments with stable pH values of 6.3 and 7.3 respectively were found in actively converting cells. The pH values were independent of the external pH and were visible already upon exposing the cells to anoxic conditions. The lower pH value was assigned to the anammoxosome, whereas the pH of 7.3 was assigned to the riboplasm. The stability of the pH in both compartments is a strong indication that the anammoxosome is the locus of the catabolism and thus functionally resembles the eukaryotic mitochondrion.Applied Science
Sustainability in Inland Shipping: The use of LNG as Marine Fuel
No full textLNG has the potential to reduce echaust gas emissions from vessels. The report explains the basics of LNG: what is it, what are the technical challenges of using LNG as marine fuel, which infrastructure is needed to bunker it and what is the impact on the costs. The report concludes with some measures to assure the succesful adoption of LNG as a marine fuel.Mechanical, Maritime and Materials Engineerin
Electromagnetic effects in anti-Hermitian media with gain and loss
No full textFunding Information: L.F. was partly supported by DoinQTech, Jane and Aatos Erkko Foundation. L.F. and M.S.M. thank X. Wang, M. Nyman, and B. Zerulla for their invaluable help with numerical simulations. Also, L.F. wishes to acknowledge the support of Carsten Rockstuhl. Publisher Copyright: © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Incorporating both gain and loss into electromagnetic systems provides possibilities to engineer effects in unprecedented ways. Concerning electromagnetic effects in isotropic media that have concurrently electric and magnetic responses, there is, in fact, a degree of freedom to distribute the gain and loss in different effective material parameters. In this paper, we analytically scrutinize wave interactions with those media, and, most importantly, we contemplate the extreme scenario where such media are anti-Hermitian. Considering various conditions for excitation, polarization, and geometry, we uncover important effects and functionalities such as lasing into both surface waves and propagating waves, conversion of evanescent source fields to transmitted propagating waves, full absorption, and enhancing backward to forward scattering ratio. We hope that these findings explicitly show the potential of anti-Hermiticity to be used in optical physics as well as microwave engineering for creating and using unconventional wave phenomena.Peer reviewe
Method of treating ammonia-comprising waste water
No full textThe invention relates to a method of treating ammonia-comprising waste water in which the bicarbonate ion is the counter ion of the ammonium ion present in the waste water. According to the invention half the ammonium is converted into nitrite, yielding an ammonia- and nitrite-containing solution, and in the second step the nitrite is used as oxidant for the ammonia. In the method according to the invention the conversion of half the ammonia into nitrite occurs automatically, providing a method which requires fewer controls. Also, the method according to the invention requires no external additiveApplied Science
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