An Ultra-Wideband Vivaldi Antenna System for Long-Distance Electromagnetic Detection

Enlarging or reducing the antenna beam width of antennas can improve the positioning capability of detection systems. A miniaturized and easily fabricated ultra-wideband (UWB) antenna system for long-distance electromagnetic detection is proposed in this article. Two ultra-wideband Vivaldi antennae were designed. One was the transmitting antenna with a beam width of 90° or above, the other was a narrow beam antenna array with beam width less than 10°, as a receiving antenna. Both proposed antennae feature broadside gain diagrams with stable radiation patterns and wideband impedance matching in the frequency range between 2.5 GHz and 4 GHz. After detecting their frequency and time-domain behaviors, the detection system can achieve measurements covering a radius of 30 m.

Current Review of Delta Variant of SARS-CoV-2

Mutations are causing SARS-CoV-2 to alter its genetic structure to improve its potential to elude the immune system, making vaccine buildout against the virus more difficult. Multiple SARS-CoV-2 variants have been found up to this point; based on their impact on public health some are considered variants of concern (VOCs) and some are considered variants of interests. VOCs are linked to superior transmissibility, a decline in neutralization by natural or vaccine induced antibodies, evading capability of detection, and a reduction in the efficacy of vaccines or therapeutics. In this article, a SARS-CoV-2 subtype, known as Delta, has been revised to provide the current state of the art and an appropriate foundation for future research works. The evolution, pathogenesis, current trends of transmission, associated symptoms, suggested prevention and treatments, and vaccine efficacy of Delta variant are reviewed and discussed.

Outdoor Target Positioning Using Wii Remote IR Camera and Signal Modulation

This paper investigates the use of the Wii remote IR (infrared) camera for outdoor target positioning. The Wii remote IR camera is widely used in various applications because of its capability of detection of up to four IR light sources with a fast frame rate (100 Hz) and a relatively low price. However, previous applications are limited to indoor uses due to the obvious reason of sunlight interference for outdoor applications. In this paper, a signal modulation technique is introduced, which enables the IR camera to look for a particular pattern encoded in an IR beacon. In this way, the IR camera can distinguish the IR beacon from the sunlight interference. The irradiance of the sunlight reflection is also analyzed to guarantee that the IR camera can detect the IR beacon even under extremely sunny weather conditions. As the Wii remote IR camera sensor is overloaded under an extremely bright condition that blocks the camera to see any light sources, we propose the use of a filter to dim the camera. Experimental results for outdoor tests are provided to validate the proposed methods.

Handheld X-ray Fluorescence (XRF) Versus Wavelength Dispersive XRF: Characterization of Chinese Blue-and-White Porcelain Sherds Using Handheld and Laboratory-Type XRF Instruments

Almost all archaeometric studies on Chinese ceramics are carried out on the excavation materials. Therefore, a detailed, comparable database that defines different workshops and production periods already exists. But the masterpieces preserved at museums, art galleries, and/or private collections, which are artistically considered as genuine artifacts, also require similar scientific investigations to define their provenance and authenticity. The research on artworks is only possible with the use of portable, noninvasive techniques that are developing daily concerning their capability of detection limits, rate of measurement, and ease of use. In this study, the results obtained with a handheld X-ray fluorescence (XRF) (also called portable XRF) and wavelength dispersive XRF instrument were compared to evidence the efficiency and drawbacks of the portable model. To achieve this goal, 12 sherds, which represent blue-and-white porcelains of Yuan and Ming Dynasties (China), were analyzed and the chemical composition of the body, glaze, and blue decor were identified. The comparison of the results with the measurements carried out on the excavation materials, which are produced in both southern and northern China, revealed the authenticity of the artifacts. Even sodium cannot be detected with portable XRF, the distinction of different production centers is possible with the detection of major (Mg, Al, Si, K, Ca), minor (Fe, Ti), and trace elements (Zr, Sr, Rb).

High Temperature Hydrogen Attack: New NDE Advanced Capabilities — Development and Feedback

In petroleum industry, hydrogen is used in many assets. With temperature and pressure, hydrogen can damage materials. This damage is called High Temperature Hydrogen Attack (HTHA) and is a time dependent degradation mechanism that can affect the integrity of steels used for pressure containment operating above about 400°F (204°C). HTHA has caused major accidents in Petroleum Industry. API RP 941 [1] currently provides guidance for steel selection (and so susceptibility to attack) in relation to temperature and ppH2 via Nelson curves. In the last edition, 4 stages of degradation for both base metal and weld metal are described. In the past, only stage III was detectable by the combination of different Ultrasonic methods which were known as AUBT – Advanced Ultrasonic Backscatter Technique. But, capability of detection was limited to defects above 500–1000μm, correspondent to small fissures. So, it was impossible to detect early stage of degradation as steel grain size (around 50μm). For several years, performances of non-destructive techniques have rapidly increased and new advanced ultrasonic technologies are available such as: - Phased Array Ultrasonic Techniques (PAUT) - Time Of Flight Diffraction (TOFD) - Total Focusing Method (TFM) This paper describes latest techniques and results obtained by Total and French Welding Institute in laboratory, and discuss the efficiency of the methods, over real HTHA degradation blocks. An overview of TFM is also proposed by CEA who work on innovating development to increase the performance of this technique.