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An investigation into Type II solar radio bursts was carried out to understand the frequency gap between fundamental and harmonic emissions of the radio burst. This investigation focused on Type II solar radio bursts with flares and coronal mass ejections by relating the separation between fundamental and harmonic emissions. We used the Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Spectrometers (CALLISTO) and a newly designed low-frequency antenna array. This article describes the proposed new instrument in terms of its antenna design, the bandpass testing of the antenna, the new system significance in studying Type II solar radio bursts, and its comparison with other leading radio solar monitoring instruments. Upon setting up the new technology, the radio-frequency interference of the observation site at the University of Malaya was shown to emphasize the suitability of the selected site. This article also shows the preliminary results of the proposed new instrument by reporting the detection of a Type III solar radio burst that was confirmed by CALLISTO. Moreover, it also includes the optimal observation design and strategies for future detections. [ABSTRACT FROM AUTHOR]

A robust and low-profile electromagnetic band-gap (EBG) based on flexible wearable antenna covering 2.4 GHz frequency band is presented. The incorporated EBG with antenna reduces the radiation into the human body around 17 dB and decreases the impacts of frequency detuning. The overall dimension of the antenna integrated with EBG is 56 x 56 x 4 mm3 with relative impedance bandwidth of 8.3% is achieved. The proposed design has improved the gain up to 7 dBi. Specific absorption rate (SAR) assessment is also studied to certify the performance of the antenna when it is located proximity to human tissue. The flexible antenna with aforementioned performances could be chosen as a good candidate for integration into a range of wearable devices for medical application. [ABSTRACT FROM AUTHOR]

Galaxy clusters are the largest virialized systems in the Universe containing a collection of galaxies of different redshifts. The redshift distribution of galaxies in galaxy clusters is concentrated at a certain redshift range which remarkably tells us that only the galaxies in a certain radial range belong to the galaxy cluster. This leads to a boundary estimation of the cluster. Background and foreground systems are represented by a histogram that determines whether some of the galaxies are too far or too high in redshift to be counted as the member of the cluster. With the recent advances in multifibre spectroscopy, it has become possible to perform detailed analysis of the redshift distribution of several galaxy clusters in the Abell Catalogue. This has given rise to significantly improved estimates of cluster membership, extent and dynamical history. Here we present a spectroscopic analysis of the galaxy cluster A262. We find 55 galaxies fall within z = 0.0143 and 0.0183 with velocity range 4450- 5300 km s-1, and are therefore members of the cluster. We derived a new mean redshift of z = 0.016 173 ± 0.000 074 (4852 ± 22 km s-1) for the system of which we compare with our neutral hydrogen (H I) detection which peaks at 4970 ± 0.5 km s-1. It is found that the distribution of H I tends to be located at the edge of the cluster since most of spiral rich galaxies were away from cluster centre. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a wideband multiple-input-multiple-output (MIMO) antenna assembly for combined WiFi/WLAN/LTE applications. The antenna consists of two radiating triangular patches placed in a mutually orthogonal configuration. Two T-slots and a rectangular slot were cut on the ground plane to improve the return loss and isolation. The surface footprint of the antenna is 30 × 30 mm2. The antenna impedance bandwidth is 101.7% between 2280 and 7000 MHz; the reflection coefficient and mutual coupling are better than −10 dB, and −14 dB, respectively. The MIMO antenna performance characteristics are given in terms of the scattering parameters, envelope correlation coefficient, total active reflection coefficient, capacity loss, channel capacity, VSWR, antenna gain and radiation patterns. Analysis of these characteristics indicates that the design is appropriate for the target WiFi/WLAN/LTE terminal applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1733-1738, 2015 [ABSTRACT FROM AUTHOR]

A wearable C-shaped antenna based on a fabric material operating at 2.4 GHz frequency is proposed for use in flexible/wearable IoT medical systems. The wearable IoT device plays a key role in medical applications, and the antenna is a key part of it. Loading the presented antenna on the body models showed a frequency detuned with the gain and efficiency reduced from 1. 28 to −9 dB and 90% to 10%. In addition, the SAR did not meet the safety health requirement defined by the FCC or ICNIRP standards. Therefore, an "Artificial Magnetic Conductor" structure (AMC) is added to the C-shaped antenna to overcome these problems. The AMC acts as shielding material between the human skin and the presented antenna because of its 0° reflection phase, which mimics the action of the Perfect Magnetic Conductor (PMC). The overall size of the proposed design was 54 × 54 × 3.9 mm3. Numerical and experimental findings indicated that integrating the AMC structures with a C-shaped antenna was robust for body deformation and load. The C-shaped antenna worked equally well with the AMC, whether positioned in free space or on the chest or the arm of the human body. The integrated antenna with AMC structures has excellent performances. The gain and efficiency without loading on the chest were 6.49 dB and 84%, respectively. While for loaded on the chest were 6.21 dB and 81%, respectively. It also decreased the back radiation and raised the Front to Back Ration (FBR) by 13.8 dB. SAR levels have been reduced by more than 90% between the FCC and ICNIRP standards compared to the C-shaped antenna alone, which does not comply with the standards. As a result, the C-shaped integration with AMC structures is highly suitable for assembly in any wearable system. [ABSTRACT FROM AUTHOR]

A compact fabric antenna structure integrated with electromagnetic bandgap structures (EBGs) covering the desired frequency spectrum between 2.36 GHz and 2.40 GHz for Medical Body-Area Networks (MBANs), is introduced. The needs of flexible system applications, the antenna is preferably low-profile, compact, directive, and robust to the human body's loading effect have to be satisfied. The EBGs are attractive solutions for such requirements and provide efficient performance. In contrast to earlier documented EBG backed antenna designs, the proposed EBG behaved as shielding from the antenna to the human body, reduced the size, and acted as a radiator. The EBGs reduce the frequency detuning due to the human body and decrease the back radiation, improving the antenna efficiency. The proposed antenna system has an overall dimension of 46×46×2.4 mm3. The computed and experimental results achieved a gain of 7.2 dBi, a Front to Back Ratio (FBR) of 12.2 dB, and an efficiency of 74.8%, respectively. The Specific Absorption Rate (SAR) demonstrates a reduction of more than 95% compared to the antenna without EBGs. Moreover, the antenna performance robustness to human body loading and bending is also studied experimentally. Hence, the integrated antenna-EBG is a suitable candidate for many wearable applications, including healthcare devices and related applications. [ABSTRACT FROM AUTHOR]

Seismo-magnetic investigation can play an important role in the investigation of various phenomena connected with earthquakes. The main target of this study is to investigate the magnetic variations associated with the swarm seismic activity along the fault structures in Gulf of Aqaba. Instrumental seismicity of Aqaba Gulf and magnetic observations were collected and analyzed during the period of 1982–2009. Seismo-magnetic effects were investigated through comparisons of magnetic and earthquake activity for long term and diurnal variations during the observed period. The distribution of these changes exhibited a distinguishing pattern, which could be related to the seismicity in certain periods of high swarm seismic activity and/or strong earthquakes. The seismo-magnetic effects were increased slowly and gradually with swarms but they were increased abruptly with strong earthquakes. Physically, this difference in Sq manners between swarm and strong earthquakes could be interpreted in view of stress force due to earthquakes and gaps along the segments fault of Aqaba Gulf which controlled the rocks containing highly magnetic constituents. The authors concluded that the seismo-magnetic effects were appreciated as a dependent element on the seismic swarm and large earthquake variables. Each of swarm and strong earthquakes has a specific manner of seismo-magnetic effect. This can be used as a powerful tool as a short-term prediction for anticipating strong earthquakes along the segmented fault of Aqaba Gulf. [ABSTRACT FROM AUTHOR]

A comprehensive analysis of plasma and composition characteristics inside magnetic clouds (MCs) observed by the Advanced Composition Explorer spacecraft from 1998 February to 2011 August is presented. The results show that MCs have specific interior structures, and MCs of different speeds show differences in composition and structure. Compared with the slow MCs, fast MCs have enhanced mean charge states of iron, oxygen, silicon, magnesium, , , , and values. For ionic species in fast MCs, a higher atomic number represents a greater enhancement of mean charge state than slow MCs. We also find that both the fast and slow MCs display bimodal structure distribution in the mean iron charge state (), which suggests that the existence of flux rope prior to the eruption is common. Furthermore, the , , and ratio distribution inside fast MCs have the feature that the posterior peak is higher than the anterior one. This result agrees with the "standard model" for coronal mass ejection/flares, by which magnetic reconnection occurs beneath the flux rope, thereby ionizing the ions of the posterior part of the flux rope sufficiently by high-energy electron collisions or by direct heating in the reconnection region. [ABSTRACT FROM AUTHOR]

In this paper, we report a detailed analysis of recurrent jets originated from a location with emerging, canceling, and converging negative magnetic field at the east edge of NOAA active region AR11166 from 2011 March 9 to 10. The event presented several interesting features. First, a satellite sunspot appeared and collided with a pre-existing opposite polarity magnetic field and caused a recurrent solar jet event. Second, the evolution of the jets showed blowout-like nature and standard characteristics. Third, the satellite sunspot exhibited a motion toward the southeast of AR11166 and merged with the emerging flux near the opposite polarity sunspot penumbra, which afterward, due to flux convergence and cancellation episodes, caused recurrent jets. Fourth, three of the blowout jets associated with coronal mass ejections (CMEs), were observed from the field of view of the Solar Terrestrial Relations Observatory. Fifth, almost all the blowout jet eruptions were accompanied with flares or with more intense brightening in the jet base region, while almost standard jets did not manifest such obvious features during eruptions. The most important feature, the blowout jets, were inclined to faster and larger scales than the standard jets. The standard jets instead were inclined to be relatively longer-lasting. The obvious shearing and twisting motions of the magnetic field may be interpreted as due to the shearing and twisting motions for a blowout jet eruption. The statistical results show that ~30% of the blowout jets directly developed into CMEs. This suggests that the blowout jets and CMEs should have a close relationship. [ABSTRACT FROM AUTHOR]

In the present study the synthesis of a palm based ethylhexyl ester was examined through a trans- esterification reaction of palm oil methyl ester (POME) with 2-ethylhexanol (EH). A sodium methoxide in methanol solution was used as a catalyst. The reaction was carried out at a fixed pressure of 1.5 mbar by varying the temperature (80-140 °C), POME/2EH molar ratio (1:1.5-1:2.2), reaction time (0.5-4 h) and catalyst concentration (1-2% w/w). The reaction with 2-ethylhexanol involved a single step reversible reaction, thus, the reaction was completed in a very short time. The optimum conditions were obtained in less than 30 minutes with 1.5 mbar pressure, 70 °C, and 1:2 molar ratio of POME to 2EH. The analysis of the final product (ethylhexyl ester) was performed using gas chromatography which exhibited 98% of ethyl hexyl ester yield. The gas chromatography analysis of ethyl hexyl ester revealed two major esters peaks i.e. ethyl hexyl palmitate and ethylhexyl oleate. [ABSTRACT FROM AUTHOR]