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Dual radio frequency plasma source: Understanding via electrical asymmetry effect

Dual radio frequency plasma source: Understanding via electrical asymmetry effect

On the basis of the global model, the influences of driving voltage and frequency on electron heating in geometrically symmetrical dual capacitively coupled radio frequency plasma have been investigated. Consistent with the experimental and simulation results, non-monotonic behavior of dc self bias and plasma heating with increasing high frequency is observed. In addition to the local maxima of plasma parameters for the integer values of the ratio between the frequencies (n), ourstudies also predict local maxima for odd integer values of 2n as a consequence of the electrical asymmetry effect produced by dual frequency voltage sources. V C 2013 AIP Publishing LLC
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5 Lee mas

Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

Self-excited plasma series resonance is observed in low pressure capacitvely coupled radio frequency discharges as high-frequency oscillations superimposed on the normal radio frequency current. This high-frequency contribution to the radio frequency current is generated by a series resonance between the capacitive sheath and the inductive and resistive bulk plasma. In this report, we present an experimental method to measure the plasma series resonance in a capacitively coupled radio frequency argon plasma by modifying the homogeneous discharge model. The homogeneous discharge model is modified by introducing a correction factor to the plasma resistance. Plasma parameters are also calculated by considering the plasma series resonances effect. Experimental measurements show that the self-excitation of the plasma series resonance, which arises in capacitive discharge due to the nonlinear interaction of plasma bulk and sheath, significantly enhances both the Ohmic and stochastic heating. The experimentally measured total dissipation, which is the sum of the Ohmic and stochastic heating, is found to increase significantly with decreasing pressure. V C 2011 American Institute of Physics. [doi:10.1063/1.3646317]
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7 Lee mas

Antenna design solutions for radio frequency identification (RFID) tags based on metamaterial-inspired resonators and other resonant structures

Antenna design solutions for radio frequency identification (RFID) tags based on metamaterial-inspired resonators and other resonant structures

Nowadays, the automatic and univocal identification of items all around the world is becoming a growing necessity, as a consequence of the rapid increase of the global production and trade. In this regard, radio frequency identification (RFID) technology has been emerging as a suitable and more evolved alternative to barcodes, being already used in a multitude of applications in everyday life, such as items tracking through the supply chain, smart inventory, access control and contactless payment. However, although RFID has achieved entering into the mainstream of technology, already providing a cost-effective solution in many scenarios, several challenges are still waiting response. Among these, the identification of small metallic objects still requires further efforts for obtaining thinner and smaller RFID tags, being the current on-metal tagging solutions thicker and much more expensive than conventional RFID tags. Also, the design of miniaturized RFID tags presenting uniform (or quasi-uniform) reading pattern, which would allow identification of small objects independently from their orientation, is still troublesome. On the other hand, some applications require maximizing the reading distance, even at the expense of the tag dimensions, so that the design of RFID tags with optimized reading distance is another interesting research subject within the frame of RFID technology.
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167 Lee mas

Two step method for the deposition of AlN by radio frequency sputtering

Two step method for the deposition of AlN by radio frequency sputtering

This paper presents a detailed study of the influence of deposition conditions on structural and morphological properties of AlN thin films synthesized on c-sapphire substrates by radio frequency (RF) reactive sputtering. After the optimization of deposition parameters such as RF power and substrate temperature, the substrate bias has been identified as a critical variable to improve the structural properties of the AlN layers. The use of neg- ative bias leads to a decrease of the full-width at half-maximum (FWHM) of the rocking curve of the AlN­(0002) x-ray re fl ection and an increase of the grain size. However, 2 θ / ω x-ray scans of layers grown under negative bias reveal lattice disorder at the AlN/sapphire interface, which is attributed to the highly accelerated positive ions (Al + , N + , N
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5 Lee mas

Diagnostic of Capacitively Coupled Low Pressure Radio Frequency Plasma: An Approach through Electrical Discharge Characteristic

Diagnostic of Capacitively Coupled Low Pressure Radio Frequency Plasma: An Approach through Electrical Discharge Characteristic

correction factor introduced to the plasma resistance to take into account the change in drift velocity of the electrons with the variation of the electric field and the PSR effect. Since the electrons have sufficient distance to travel and accelerate in the bulk plasma at low pressure, we anticipate that the resistance of the bulk plasma changes due to the change in drift velocity of the electrons. Besides, it was reported that due to the PSR effect the measured rms current is higher than the current predicted by homogeneous discharge model [13, 14]. It has also been experimentally observed that at the beginning of the rf cycle the plasma sheath expands and as a result energetic electron beams are generated [14, 21]. The PSR effect enhances the generation of these highly energetic electron beams due to the rapid expansion of the sheath. These electrons travel from the sheath region and propagate through the bulk plasma and enhance the total plasma current. The electron neutral collision frequency can be express as [20],
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5 Lee mas

Morphology and arrangement of InN nanocolumns deposited by radio frequency sputtering: Effect of the buffer layer

Morphology and arrangement of InN nanocolumns deposited by radio frequency sputtering: Effect of the buffer layer

We present the structural and optical properties of (0001)-oriented nanocolumnar films of InN deposited on c-sapphire substrates by radio-frequency reactive sputtering. It is observed that the column density and dimensions are highly dependent on the growth parameters of the buffer layer. We investigate four buffer layers consisting of (i) 30 nm of low-growth-rate InN, (ii) 30 nm of AlN deposited on the unbiased substrate (us), (iii) 30 nm of AlN deposited on the reverse-biased substrate (bs), and (iv) a 60-nm-thick bilayer consisting of 30-nm-thick bs-AlN deposited on top of 30-nm-thick us-AlN. Differences in the layer nucleation process due to the buffer layer induce variations of the column density in the range of (2.5– 16) 10 9 cm 2 , and of the column diameter in the range of 87–176 nm. Best results in terms of mosaicity
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6 Lee mas

Structural, optical and electrical properties of ZnO thin films grown by radio frequency (rf) sputtering in oxygen atmosphere

Structural, optical and electrical properties of ZnO thin films grown by radio frequency (rf) sputtering in oxygen atmosphere

investigated as a function of the oxygen pressure during the growth of ZnO by radio frequency (rf) sputtering. The electrical behavior is explained in terms of the structural properties. Our results suggest that optimal oxygen partial pressure is 4 Pa for attaining a ZnO thin film as a buffer layer, with resistivity on the order of 10 3 Ω cm and an

10 Lee mas

20 GHz arbitrary radio frequency waveform generator based on incoherent pulse shaping

20 GHz arbitrary radio frequency waveform generator based on incoherent pulse shaping

Currently, there exist many solutions for photonically assisted AWGs [2], but those relying on spatial light modulator (SLM)–based pulse shaping offer a better performance in terms of reconfigurability [3-7]. Among these solutions, the wavelength-to-time mapping technique [4] has the potential for a broader range of operation because it can easily achieve the low-frequency regime of RF bandwidth. In this technique, the spectrum of a coherent signal (e.g., a mode-locked laser) is manipulated in a Fourier-transform pulse shaper (FTPS). Later, the synthesized energy spectrum is mapped into the time domain just by stretching the pulse in a dispersive medium. A physical interpretation of this phenomenon can be done in terms of the space-time analogy, since it is the temporal equivalent of the Fraunhofer (or far- field) diffraction [8].
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6 Lee mas

Low frequency View of GW170817/GRB 170817A with the Giant Metrewave Radio Telescope

Low frequency View of GW170817/GRB 170817A with the Giant Metrewave Radio Telescope

Taken in isolation, the GMRT 1390  MHz light curve is consistent with a plateau phase ( Figure 1 ) . However, it is also marginally consistent with the t 0.8 rise previously derived from X-ray and high radio frequency observations ( Margutti et al. 2018; Mooley et al. 2018 ) . Our last L-band light curve extends 152  days after GW170817, while the high radio frequency observations extend to 115  days. The fl atness could indeed be a slow turnover of the afterglow light curve, which was not apparent in the high radio frequency observations reported so far. 16 This conclusion is also consistent with the late-time X-ray observations reported by Troja & Piro ( 2018b ) , where the Chandra fl ux at 158 days is consistent with that at 110 days since the burst.
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10 Lee mas

Electronic identification of goats: comparison of different types of radio-frequency and visual devices

Electronic identification of goats: comparison of different types of radio-frequency and visual devices

The use of passive radio frequency (RFID) technology for goat identification has become a key issue in recent years, especially in the European Union, where its compulsory use in sheep and goats is regulated. This paper reviews research carried out so far on the use of ear tags, injectable transponders, rumen boluses, and leg tags for goat identification, basing on their retention, readability, and retrieval easiness. The healing process of ear tags is conditioned by ear tag features and the biocompatibility of making materials. Moreover, ear tag retention is highly variable, in most cases not reaching the long-term (12 mo) readability of at least 98% required by the International Committee of Animal Recording. Button ear tags have been suggested to offer suitable readability, and are regarded for official use in different official programs. The subcutaneous injection of encapsulated transponders in different body locations has also been evaluated, mainly focusing on readability and migration results. Injection in the armpit offers the greatest readability in goats, although it is subjected to the greatest migration rates. Injection in the extremities has also been considered, although smaller transponders are used in this case, thereby compromising their reading distance. The main drawback of injectable transponders is their deficient retrieval at slaughter. The retention of rumen boluses has shown a remarkable variability in goats, and the influence of breed and feeding management on losses has been suggested. Most studies have indicated lower retention rates in goats than in other ruminant species. Even though, a regression model of bolus retention according to bolus weight and volume has been proposed, similarly to previous models established for sheep and cattle. According to this model, especially heavier and denser boluses are required in the case of goats to ensure that the device is permanently retained. Considering radio translucent materials currently available, suitable boluses for goat identification can be efficiently produced. Different RFID leg tags have also been proposed, especially for dairy goats in the milking parlor. The proper circumference of the leg band is recognized as a key aspect to be studied in this case as it seriously conditions the identification at early ages, while preventing the unlawful removal during the goat lifespan. Electronic readability of leg tags is greatly influenced by the type of transponder.
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159 Lee mas

Evaluation of Microbicidal Activity of Oxygen-Containing Plasmas using Biological Monitors with Different Lumen Calibers

Evaluation of Microbicidal Activity of Oxygen-Containing Plasmas using Biological Monitors with Different Lumen Calibers

against a standard load of Bacillus atrophaeus spores inoculated on glass carriers inside PVC catheters. The sterilization efficiency was studied as a function of plasma system (reactive ion etching or inductively coupled plasma), biological monitor lumen diameter, gas, radio frequency power, and sub-lethal exposi- tion time. After sterilization, the biological monitors were disassembled and the surviving bacteria were grown in trypticase soy broth using the most probable number technique. Plasma antimicrobial activity depended on the catheter’s internal diameter and radio frequency powers. The O 2 + H 2 O 2 mixture exhib-
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1 Lee mas

Geodesic dome frequency 4

Geodesic dome frequency 4

The aim of this project is to assess the potential of building an icosahedral geodesic hemispherical structure with frequency 4. The dome is a 4.2 m radius hemisphere and built in wood (weather resistant) with the binding elements in metal. It has a door and 3 windows distributed in the 4 quadrants. The whole structure has good thermal insulation properties and is watertight.

42 Lee mas

1. Los antecedentes de la radio - LA RADIO

1. Los antecedentes de la radio - LA RADIO

En la actualidad, si analizas la oferta de las distintas emisoras te será muy fácil comprobar que la utilización de la música no es siempre la misma. Así, si en algunas ocasiones se te brinda la oportunidad de escuchar íntegramente una canción, en otras simplemente se te ofrece la posibilidad de percibir una melodía que suena de fondo mientras un locutor o una locutora te invita, por ejemplo, a que te apuntes a una academia para mejorar tu inglés. Todo depende, como ahora veremos, del programa que estés sintonizando, de las intenciones del emisor y, sobre todo, del contexto en el que se integre la música. Ten en cuenta que, aunque cualquier composición es susceptible de despertar determinadas sensaciones y emociones en aquel que la escucha, su significado en radio puede variar a partir la relación que guarde con otros
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11 Lee mas

La Radio en Argentina Documento de cátedra

La Radio en Argentina Documento de cátedra

Los programas musicales continuaron siendo un número fuerte, aunque volcados por entonces hacia géneros más populares que la música clásica. Las orquestas típicas, las de jazz, los solistas de moda y hasta el recitador eran los ingredientes esenciales de un buen show radiofónico. Son además años de crecimiento del folklore. En 1937 La tropilla de Huachi Pampa, imponía el gusto mayoritario en su programa El Fogón de los Arrieros. La Tropilla de Huachi Pampa fue el primer conjunto de música folclórica, dirigido por el sanjuanino Buenaventura Luna, en transmitir sus interpretaciones por radio, con impacto nacional.
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6 Lee mas

Grid frequency control. . Secondary frequency control tuning taking into account distributed primary frequency control

Grid frequency control. . Secondary frequency control tuning taking into account distributed primary frequency control

Fig. 1 displays a simplified block diagram of the grid frequency control. This block diagram is only valid to obtain the mean value of grid frequency in the long term. The grid frequency control has the following variables: Electrical Power (PE), Frequency (F), Frequency Set Point (F SP) and Mechanical Power (PM) of generators.

1 Lee mas

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