Miracle-dz/UniFAR-FTUs huggingface dataset:
Leaky wave radiation phenomena in metamaterial transmission line based on complementary split ring resonators

This article discusses radiation phenomena in a metamaterial leaky wave antenna working around 3 GHz and enabling a frequency beam steering simultaneously in the plane of the substrate and in its normal plane.The structure is based on a metamaterial transmission line periodically loaded by series capacitive gaps and complementary split ring resonators. Full‐wave simulations and measurements of radiation pattern show a minimum in the broadside direction, creating a rotating beam splitting in the plane of the substrate. This phenomenon is successfully correlated to a particular current pattern observed on the microstrip conductors of the structure. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26208
Microwave circuit miniaturization with complementary spiral resonators: Application to high‐pass filters and dual‐band components

In this contribution, it is shown that complementary spiral resonators (CSRs) are useful particles for the miniaturization of planar microwave components based on metamaterial concepts. Specifically, we will focus on two different applications: (i) the design of high pass filters based on balanced composite right/left handed microstrip lines and (ii) the design of dual band impedance inverters, which can be applied to many different devices such as couplers and power dividers, among others. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2741–2745, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24715
Miniaturised printed elliptical nested fractal multiband antenna for energy harvesting applications

This study presents the design, optimisation, simulation and fabrication of a novel printed elliptical nested fractal (planar) antenna for multiband operation. The proposed antenna is intended to function as the receptor element in radio-frequency energy harvesting applications. The simple microstrip structure and the compact size of the antenna ease its fabrication and allow it to be integrated with other electronic circuitry. It consists of nested elliptical structures fed by 50 Ω microstrip line with complementary elliptical ground along with rectangular ground plane. The added Hilbert structures at both sides of the antenna feeding line on the top layer enhance its performance to operate in multi-frequency bands. This antenna exhibits good radiation and reflection characteristics at 910 MHz (global system of mobile (GSM 900)), 2.4 GHz (Bluetooth/wireless local area network), 3.2 GHz (Radiolocation, third generation (3G)), 3.8 GHz (for long-term evolution, 4G) and additional 5 GHz band (wireless fidelity signals). The overall dimension of antenna is 41 mm (width) × 44 mm (length) × 1.778 mm (thickness). To the best knowledge of the authors, this is the widest bandwidth antenna to be developed at these small dimensions covering major standards from 900 MHz up to 6 GHz for electromagnetic energy harvesting applications.
Growth of Rutile TiO2 Nanorods by Chemical Bath Deposition Method on Silicon Substrate at Different Annealing Temperature

Effects of annealing treatment on growth of rutile TiO2 nanorods on structural, morphological and optical properties of TiO2 nanorods were investigated. The nanorods were fabricated on p-type (111)-oriented silicon substrates and, all substrates were seeded with a TiO2 seed layer synthesized by radio-frequency reactive magnetron sputtering system. Chemical bath deposition (CBD) was carried out to grow rutile TiO2 nanorods on Si substrate at different annealing temperatures (350, 550, 750, and 950 °C). Raman spectroscopy, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analyses showed the tetragonal rutile structure of the synthesized TiO2 nanorods. Optical properties were examined by photoluminescence spectroscopy. The spectra exhibit one strong UV emission peak which can be seen at around 390 nm for all of the samples. In the visible region, TiO2 demonstrated two dominant PL emissions centered at around 519 and 705 nm. The experimental results showed that the TiO2 nanorods annealed at 550 °C exhibited the optimal structural properties. Moreover, the CBD method enabled the formation of photosensitive, high-quality rutile TiO2 nanorods with few defects for future optoelectronic nanodevice applications.
On the Impact of Channel Cross-Correlations in High-Sensitivity Receivers for Galileo E1 OS and GPS L1C Signals

One of the most promising features of the modernized global navigation satellite systems signals is the presence of pilot channels that, being data-transition free, allow for increasing the coherent integration time of the receivers. Generally speaking, the increased integration time allows to better average the thermal noise component, thus improving the postcorrelation SNR of the receiver in the acquisition phase. On the other hand, for a standalone receiver which is not aided or assisted, the acquisition architecture requires that only the pilot channel is processed, at least during the first steps of the procedure. The aim of this paper is to present a detailed investigation on the impact of the code cross-correlation properties in the reception of Galileo E1 Open Service and GPS L1C civil signals. Analytical and simulation results demonstrate that the S-curve of the code synchronization loop can be affected by a bias around the lock point. This effect depends on the code cross-correlation properties and on the receiver setup. Furthermore, in these cases, the sensitivity of the receiver to other error sources might increase, and the paper shows how in presence of an interfering signal the pseudorange bias can be magnified and lead to relevant performance degradation.
Death by lightning

Modern knowledge of the amplitudes and waveshapes of lightning currents enables a method of determining the electrical effects of a direct lightning stroke to be established. It has been shown that this entails an initial current discharge through the body, followed by an external flashover. The amplitude and waveshape of the current flowing through a body can thus be determined. The phenomenon of a back flashover, which is a familiar concept to h.v. transmission engineers, is paralleled by the so-called side flash to a person or animal, e.g. when sheltering under a tree or in close proximity to a metal fence. Another possibility is a direct stroke to earth, producing so high a potential drop over the ground surface as to paralyse or shock people over a wide area. From the medical point of view, it is important to apply this knowledge to understand the nature of the current and its pathway through the body. It may then be possible to postulate the possible effects of the lightning stroke on the different bodily systems. While clearly it is not possible to test these conclusions by planned investigations, they may be examined in the light of reported observation from accidents.
Design and fabrication of a foldable 3D silicon based package for solid state lighting applications

Miniaturization of solid state lighting (SSL) luminaires as well as reduction of packaging and assembly costs are of prime interest for the SSL lighting industry. A novel silicon based LED package for lighting applications is presented in this paper. The proposed design consists of 5 rigid Si tiles connected by flexible polyimide hinges with embedded interconnects (ICs). Electrical, optical and thermal characteristics were taken into consideration during design. The fabrication process involved polyimide (PI) application and patterning, aluminium interconnect integration in the flexible hinge, LED reflector cavity formation and metalization followed by through wafer DRIE etching for chip formation and release. A method to connect chip front to backside without TSVs was also integrated into the process. Post-fabrication wafer level assembly included LED mounting and wirebond, phosphor-based colour conversion and silicone encapsulation. The package formation was finalized by vacuum assisted wrapping around an assembly structure to form a 3D geometry, which is beneficial for omnidirectional lighting. Bending tests were performed on the flexible ICs and optical performance at different temperatures was evaluated. It is suggested that 3D packages can be expanded to platforms for miniaturized luminaire applications by combining monolithic silicon integration and system-in-package (SiP) technologies.
isotope effects

• Traditional kinetics studies do not provide information as to what bonds are broken/formed and changes in hybridization that occur during the rate-limiting step of a reaction. • Isotope effects can provide this information. • Substituting one iosotope for another at or near an atom at which bonds are breaking or rehybridizing typically leads to a change in the rate of the reaction. • The effect of replacing H with D often is relatively large when the bonds being broken or formed involve H. This effect can be measured routinely. • The effects of isotope replacement for other elements have been studied, but the effects are typically small and sometimes difficult to quantify.
A Simplified Time-Domain Channel Estimation Approach for OFDM System

OFDM usually incorporates pilot tones in the frequency domain (FD) or training symbols in the time-domain (TD) to facilitate channel estimation algorithms. TD channel estimation becomes more attractive in quasi-static channels because channel estimation scheme will optimize the spectral efficiency by re-using the training symbols designated for FD channel estimation. A channel estimation method based on time domain averaging algorithm is proposed. Due to the principle of centralized energy in time domain, the effective channel impulse response length can be detected by setting of threshold for the estimated channel impulse response length. Computer simulation demonstrates the performance of the proposed algorithms in terms of bit error rate performance.
Compact design of T‐type monopole antenna with asymmetrical ground plane for WLAN/WiMAX applications

The article proposed and studied a compact coplanar waveguide‐feed antenna for WiMAX applications. In this design, using notches on the ground plane and trapezoid‐feed line is to generate broadband operation of 10‐dB return loss from 1.95 to 6.55 GHz. Furthermore, embedded a narrow slit etching on the radiation patch accounts for triple‐band operation of 1.68–2.71 GHz, 3.26–4.06 GHz, and 5.03–6.24 GHz. It plays a role as a filter to eliminate the undesired band. The proposed antenna with a band‐reject characteristic is calibrated for WLAN/WiMAX applications which covers the band from 2.4 to 2.7, 3.3 to 3.8, and 5.15 to 5.85 GHz. And, this antenna has advantages of good radiation characteristics, compact size, and omni‐directional patterns. Details of the proposed antenna configuration and experimental results are discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 515–519, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23120
Which Polishing Method Is Effective for Coffee Stains? – An In-Vitro Study of Surface Roughness and Color Change

Objective: To assess the effects of three different polishing protocols on the surface roughness and color change of the enamel and compare the results with the enamel specimens exposed to coffee. Methods: Seventy-two bovine enamel specimens were randomly divided into two groups-Group I: only polishing, Group II: immersion in coffee solution and polishing–which were then subdivided into three groups according to polishing procedures as follows: polishing with rubber cup and Pumice Flour (PF), polishing with rubber cup and Prophy Paste (PP), polishing with Air Abrasion (AA). Surface roughness (Ra) and tooth color were assessed using a surface profilometer and a digital spectrophotometer. The color change was determined by the CIE L*a*b* system. One specimen from each group was also examined by SEM. Statistical analyses were performed by GraphPad software. Kruskal-Wallis and Friedman tests were used for multiple comparisons between-groups and in-groups, respectively. Results: At baseline measurements, no significant differences were found among groups in terms of roughness and color values (p>0.05). In Group I, surface roughness values and color change were similar after polishing (p=0.393, p=0.093, respectively). In Group II, post-polishing Ra values were significantly increased in all groups (p<0.05) and the highest ΔE value was detected in PP group. Conclusion: Following coffee immersion, enamel surfaces become rougher in all polishing protocols and the roughest surface was in PF group. In all study groups visible clinical success was achieved in terms of color; therefore, dental clinicians should prefer PP in clinical practice due to the less abrasive and sufficient color change properties.
Active noise suppression of smart panels including piezoelectric devices and absorbing materials

In this paper, noise reduction performance of piezoelectric smart panels is experimentally studied. Piezoelectric smart panel is comprised of plate structure on which piezoelectric sensor/actuators are bonded and sound absorbing materials. The concept of piezoelectric smart panels is to combine passive and active strategies such that the noise reduction can be effectively achieved over a broad frequency range. The noise reduction performance is tested on an acoustic tunnel. The tunnel is made of a guided tube having a square cross section and loud speaker is installed at one end as a sound source while nonreflection terminator is attached at the other end. The panels can be mounted in the middle of the tunnel and the transmission as well as reflection of panels can be measured. Noise reduction performance of a single plate with absorbing material shows a good result at mid frequency region but little effect in the resonance frequencies. When the active control scheme is activated, a remarkable noise reduction is observed at the resonance. The combined use of absorbing materials and piezoelectric active devices brings the simultaneous noise reduction in mid and low frequency regions. It can be concluded that piezoelectric smart panels incorporating passive absorbing material and active piezoelectric devices, is a promising technology for noise reduction in a wide band frequency.
Resonant frequency of asymmetrically loaded annular microstrip antenna

Theory of resonant frequency of an annular ring antenna with asymmetric multiple shorting posts is presented using modified Cavity Model. The posts are thin in diameter with respect to the diameter of ring. For accurate formulation, the shorting posts have been considered as inductive impedances at the frequency of interest. It is shown that for asymmetric loaded ring, TM11 is the dominant mode. The simple tool presented can be suitably modified to incorporate switching diodes or varactor diodes. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2351–2353, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23673
Residual mechanical properties of calcareous and granite aggregate concretes after fire

The residual mechanical properties of concrete after a fire depend on the high temperatures to which the material was subjected and the nature of the fire extinguishing process used. Knowledge of these properties is of the utmost importance in an evaluation of the residual load-bearing capacity of reinforced concrete elements and their repair after fire. This paper presents the results of an assessment of the residual mechanical properties of ordinary concrete after fire. Concretes comprising granite and calcareous aggregates were studied as they are commonly used around the world in civil engineering construction. The study considered different loading levels (0·3fcd and 0·7fcd), different cooling processes (cooling in air and by water jet) and varying maximum temperatures of concrete exposure (20, 300, 500 and 700°C). The mechanical properties of the concretes (residual compressive strength, direct and splitting tensile and flexural strengths and modulus of elasticity) after being subjected to high temp.
Spectral distribution of a sampled 1st-order lowpass filtered white noise

In the letter, the spectrum of a sampled 1st-order lowpass filtered white noise is calculated, and theoretical results are compared with measurements made on a laboratory model. In this context, the effect of undersampling appears clearly for noise bandwidths exceeding the sampling rate. This analysis contributes to the study of noise in switched capacitor networks.
Group Key Management Mechanism for Secure Device in AMI Environment

Many researches have proposed key management schemes for Smartgrid System. However, previous studies lack the proper considerations for availability and device security. In this paper, we build up cryptographic security improvement for robust Smartgrid Systems. In addition, we propose a public-key management and hash function architecture for robust Smartgrid Systems which supports reduces the number of key and Secure Device in AMI network environments.
Biomass gasification or combustion for generating electricity in Spain: Review of its current situation according to the opinion of specialists in the field

This paper seeks to set out the problems of biomass-based electricity generation according to the opinions of specialists in the sector with considerable experience both in the undertaking of projects involving the management and operation of facilities, and in research projects involving combustion and gasification technologies. The aim is to analyse both technologies and decide which is the more suitable and in what circumstances, and to describe the technological and circumstantial problems each one currently faces. In general, it is stressed that these two technologies are still in their infancy, and they require major efforts in research, although the first fruits are already being gathered for each one at an appropriate scale. Some experts recommend using the gasification technique in plants with an installed electric power of between 0.5 and 2 MWe, while in plants between 2 and 10 MWe combustion is considered to be more reliable. A key factor in the viability of both types of facilities is the need.
Analysis of the Hexagonal Split Ring Resonator using Machine Learning by Considering Split Gap as a Prime Factor

The Hexagonal split-ring resonators (HSRR) are one of the prime elements of metamaterial and patch antenna design in the millimetre-wave range. Even though it's widely used there is no particular mathematic model is available for it. This analysis presents the mathematical nature of the relation between split widths, resonance frequencies; reflection (s11) and mutual coupling (s12) by identifying tend of the data with the aid of machine learning algorithms. The predicted relation will help to design efficient metamaterial, antennas and related appliances.
Efficient Label Gathering for Machine Training:Results from Muon Hunter 2

In 2017, the Muon Hunter project on the Zooniverse.org citizen science platform successfully gathered more than two million classiﬁcation labels for nearly 140,000 camera images from VERITAS. The aim was to select and parameterize muon events for use in training convolutional neural networks. The success of this project proved that crowdsourcing labels for IACT image analysis is a viable avenue for further development of advanced machine-learning algorithms. These algorithms could potentially lend themselves to improving class separation between gamma-ray and hadronic event types. Nonetheless, it took two months to gather these labels from volunteers, which could be a bottleneck for future applications of this method. Here we present Muon Hunters 2.0: the follow-on project that demonstrates the development of unsupervised clustering techniques to gather muon labels more efﬁciently from volunteer classiﬁers.
LCT and PIV Investigations Behind Trapezoidal-Rib With a Slit Mounted on Bottom Wall of a Rectangular Duct

Various rib turbulator geometries have been used earlier to investigate the heat transfer and fluid flow characteristics owing to its vast industrial applications. Permeable ribs are reported to provide better performance in terms of heat transfer enhancement and pressure penalty. The trapezoidal rib with variable downstream chamfering and a centrally placed longitudinal slit has been used for the detailed flow field and heat transfer investigations using particle image velocimetry and liquid crystal thermography. Objective of the present work is to study the combined effect of rib chamfering along with a continuous slit and establish an understanding of the underlying flow mechanism and the corresponding heat transfer distribution. Experiments were carried out for hydraulic diameter based Reynolds numbers of 61480 in a rectangular duct for flow over rib with 12.5% blockage ratio and 25% open area ratio. The chamfer angles were varied from 0 to 20 degree. It has been observed that the slitted rib cause shorter reattachment length and reduced pressure penalty as compared to its solid counterpart.Copyright © 2012 by ASME
Identification of degradation mechanisms in a bipolar linear voltage comparator through correlation of transistor and circuit response

The input bias current (I/sub IB/) of the National LM111 voltage comparator exhibits a non-monotonic response to total dose irradiations at various dose rates. At low total doses, below 100 krad(SiO/sub 2/), increased I/sub IB/ is due primarily to gain degradation in the circuit's input transistors. At high total doses, above 100 krad(SiO/sub 2/), I/sub IB/ shows a downward trend that indicates the influence of compensating circuit mechanisms. Through correlation of transistor and circuit response, the transistors responsible for these compensating mechanisms are identified. Non-input transistors in the circuit's input stage lower the emitter-base operating point voltage of the input device. Lower emitter-base voltages reduce the base current supplied by the input transistors, causing a moderate "recovery" in the circuit response.