Peak Radiation Research Articles

An empirical model of noise sources in subsonic jets

Modelling the noise emitted by turbulent jets is made difficult by their acoustic inefficiency: only a tiny fraction of the near-field turbulent kinetic energy is propagated to the far field as acoustic waves. As a result, jet-noise models must accurately capture this small, acoustically efficient component hidden among comparatively inefficient fluctuations. In this paper, we identify this acoustically efficient near-field source from large-eddy simulation data and use it to inform a predictive model. Our approach uses the resolvent framework, in which the source takes the form of nonlinear fluctuation terms that act as a forcing on the linearised Navier–Stokes equations. First, we identify the forcing that, when acted on by the resolvent operator, produces the leading spectral proper orthogonal decomposition modes in the acoustic field for a Mach 0.4 jet. Second, the radiating components of this forcing are isolated by retaining only portions with a supersonic phase speed. This component makes up less than 0.05 % of the total forcing energy but generates most of the acoustic response, especially at peak (downstream) radiation angles. Finally, we propose an empirical model for the identified acoustically efficient forcing components. The model is tested at other Mach numbers and flight-stream conditions and predicts noise within 2 dB accuracy for a range of frequencies, downstream angles and flight conditions.

Design and Beam Dynamic Studies of an Injector for a Compact THz Coherent Radiation Source

An intense narrow-band terahertz (THz) radiation source has been designed to generate a broad tuning range of radiation frequencies between 0.5 THz and 5.0 THz. The THz radiation is produced when a short-bunch electron beam propagates through an undulator. To achieve high-power peak radiation, the source requires high-brightness electron beams with low beam emittance and short bunch length. A proposed design for the photocathode RF gun used as the electron source is presented. The gun with high mode separation and high Q-factor can be achieved for producing a good beam quality. The beam dynamics of the injector have been preliminarily optimized using the software ASTRA and Elegant, investigating the impact of laser pulse shape on electron beam quality. The results of the beam dynamics studies are comprehensively discussed in this paper.

Performance evaluation of PV panels for green HHO gas generation: Energy, exergy, and economic investigation

The paper aim is to design and fabricate of solar-powered alkaline water electrolyzer to produce hydroxy gas (HHO) flow with enhanced efficiency. Oxyhydrogen gas was yielded by the electrolysis of water utilizing various NaOH concentrations of 5, 10, 15 and 20%. Based on the solar radiation peak time at 12:00 p.m., the increase of solar intensity from 502 W/m2 to 1000 W/m2 (from 08:00 AM to 12:00 PM) led to the current and voltage increases by about 700% and 450%, respectively. Cell efficiency increase was from 61% to 69% by about 13% increase ratio. The output of HHO increases with cell gap between 1 and 3 mm. For temperatures between 30 °C and 60 °C, HHO generation declines at the gaps of cells between 4 and 7 mm. At the same operating temperature, the cells gap of 1, 3, 4, and 7 mm produced flow rates of 928, 975, 960, and 925 ml/min, respectively. After 30 min, the rate of HHO achieves the maximum values of 866, 985, 1090, and 1140 ml/min at NaOH concentrations of 5, 10, 15, and 20%. The simplicity, ease of assembly, and manufacture of the dry cell made it appealing. The HHO dry cell is affordable, made from readily available components, and adaptable to engines that receive their power from solar panels. The cost per liter to produce HHO varies between 0.437 and 0.575 $.

Investigation on the multimodal failure characteristics of cement mortar under uniaxial compression loading

The physical condition and durability of cement-based structures can easily decrease after years of operation due to exposure to severe scenarios associated with internal defects, aggressive usage, and continuous load changes. Therefore, accurately assessing such infrastructures is essential for ensuring safety and serviceability and preventing hazards. In this study, an experimental investigation of the multimodal failure characteristics of cement mortar with various sand contents at different uniaxial compressive loading rates was conducted. Specifically, the multimodal failure characteristics include three main categories: mechanical properties (e.g., compressive strength), one-dimensional signals (e.g., micro-vibration and electromagnetic radiation), and two-dimensional videos/images (e.g., crack propagation trajectory). A geophysical acquisition and a high frame rate camera were employed to simultaneously record the micro-vibration, electromagnetic radiation and crack propagation videos of the cement specimens in a uniaxial compression test. Based on the computer vision technique and the feature pyramid network (FPN), an automatic pixel-level crack segmentation method was proposed to extract cracks of each critical moment in the fracture video. Then, the fractal dimension and crack area were calculated to quantitatively depict the crack propagation trajectory. Finally, the stress drop, micro-vibration, electromagnetic radiation, and crack propagation trajectory characteristics were analysed and discussed. The experimental results indicate the following. (1) The FPN offers a practical way to identify cracks in structures of cement-based materials at the pixel-level. (2) The micro-vibration, electromagnetic radiation, and crack propagation trajectory exhibit good consistency. In particular, the area and fractal dimension of cracks positively correlate with the stress drop of cement under compression loading. (3) The peak and cumulative energy values of micro-vibration and electromagnetic radiation tend to increase as the sand content increases when subjected to the same loading rate.

Research on infrared radiation response and energy dissipation characteristics of sandstone crushing under impact load

This study is aimed at investigating the infrared radiation (IR) response and energy dissipation characteristics of sandstone crushing under different impact velocities. To achieve this aim, first, we conducted IR experiments involving sandstone crushing based on drop-hammer impact. Next, the variations in infrared radiation temperature (IRT), infrared thermal imaging, and energy of sandstone crushing under different impact velocities were studied, and the characteristics of sandstone crushing and particle size distribution were also explored. In addition, the correlation between IR parameters and mean particle size of sandstone crushing was determined, and the correlation between IR parameters and fractal dimension was evaluated. The following results were obtained: the peak increments of the maximum infrared radiation temperature (MIRT) and average infrared radiation temperature (AIRT) increase with the increase of impact velocity, and the time of the maximum infrared radiation peak temperature lags that of average infrared radiation peak temperature (AIRPT). Under the same colorimetric scale, the IRT of sandstone surface is higher when the impact velocity is larger, and the differentiation characteristics of infrared thermal images are greater; on the contrary, the IRT of sandstone surface is lower when the impact velocity is lower, and the differentiation between infrared thermal images is more difficult. The peak increments of MIRT and AIRT increase with impact energy, absorption energy, impact energy density, and absorption energy density in cubic function. The mean particle size of sandstone fragments decreases linearly with the increase of impact velocity, and the fractal dimensions increase with impact energy density and absorption energy density in a negative exponential manner. The peak increments of MIRT, AIRT, and infrared radiation energy (IRE) have a good correlation with the mean particle size and fractal dimension of sandstone fragments, which can characterize the degree of sandstone crushing and particle size distribution under impact load.

Forecasting the Distortion in Solar Radiation during Midday Hours by Analyzing Solar Radiation during Early Morning Hours

Knowing the fluctuation of solar radiation is essential for reliable and safe operation of power systems with a high share of solar PV power plants. This paper introduces a novel method for forecasting the distortion in global solar radiation during the midday time (during the peak of solar radiation at which the generation of the PV plants is maximum), by analyzing the solar radiation during the very early hours. This paper shows that there is a strong relation between the condition of the solar radiation during the very early minutes of the day (when the generation of the PV plants is low) and the condition of the solar radiation during the midday hours (when the output of the PV plants is enormous). This relation can be utilized to help power systems operators in determining the safe share of PV plants that can be fed to power systems. We analyzed real data of one complete year for two sites in Saudi Arabia to approve this approach. The difference between each two readings was calculated for the hours 7 a.m. and 8 a.m. Then, the negative, zero, and amplitude of the difference was used to formulate a distortion index (DI) that predicts the distortion/fluctuation in the global radiation. It was concluded that the DI could classify the days into three categories: clean, distorted, and medium level according to the value of the DI. The accuracy of this approach was 85.2% and the error was 14.8%.

A Compact 2.4 GHz L-Shaped Microstrip Patch Antenna for ISM-Band Internet of Things (IoT) Applications

Wireless communication technology integration is necessary for Internet of Things (IoT)-based applications to make their data easily accessible. This study proposes a new, portable L-shaped microstrip patch antenna with enhanced gain for IoT 2.4 GHz Industrial, Scientific, and Medical (ISM) applications. The overall dimensions of the antenna are 28 mm × 21 mm × 1.6 mm (0.22λo × 0.17λo × 0.013λo, with respect to the lowest frequency). The antenna design is simply comprised of an L-shape strip line, with a full ground applied in the back side and integrated with a tiny rectangular slot. According to investigations, the developed antenna is more efficient and has a greater gain than conventional antennas. The flexibility of the antenna’s matching impedance and performance are investigated through several parametric simulations. Results indicate that the gain and efficiency can be enhanced through modifying the rectangular back slot in conjunction with fine-tuning the front L-shaped patch. The finalized antenna operates at 2.4 GHz with a 98% radiation efficiency and peak gains of 2.09 dBi (measured) and 1.95 dBi (simulated). The performance of the simulation and measurement are found to be in good agreement. Based on the performance that was achieved, the developed L-shaped antenna can be used in a variety of 2.4 GHz ISM bands and IoT application environments, especially for indoor localization estimation scenarios, such as smart offices and houses, and fourth-generation (4G) wireless communications applications due to its small size and high fractional bandwidth.

Wideband Circularly Polarized mm-Wave Array Antenna Using H-Shaped Low-Axial-Ratio Apertures

An H-shaped all-metal radiating element comprising an active and a coupled slot has been proposed to design wideband high-efficiency circularly-polarized antenna arrays. The proper excitation of several modes on the coupled slot enables a wide axial ratio bandwidth with high circular polarization purity. In order to feed an array of such radiating elements, a simple and scalable two-layer corporate network, implemented in groove gap waveguide technology, is conceived. Those good frequency properties have been confirmed by the fabrication of a prototype, whose experimental results report a 1-dB axial ratio bandwidth of 22%. In addition, a peak radiation efficiency of 97% with good pattern stability, and an impedance bandwidth of 21% with high return loss, have been measured. The high circular polarization purity demonstrated by these wideband apertures makes them particularly suitable for Ka-band satellite communications antennas.

Experimental assessment of energy tower's performance: evaluation of the impacts of solar radiation, humidity, and chimney's height on the overall efficiency.

Solar energy is one of the most feasible options to produce energy in countries where unexploited desert areas or solar radiation are abundant. An energy tower is an effective system for electrical power generation that can perform more efficiently along with solar radiation. As the primary aim of the present study, effects of different environmental parameters on total efficacy of energy tower were investigated. In this study, the efficiency of the energy tower system is investigated experimentally by an indoor fully adjustable apparatus. In this regard, a comprehensive set of influencing parameters like air velocity, humidity, and temperature and the effects of tower height on the performance of the energy tower are individually assessed. It is demonstrated that there is a direct relationship between an increase in humidity percentage of the surrounding and performance of energy tower, meaning that a 274% increase in humidification rate led to 43% elevation in airflow velocity. The kinetic energy increases in the direction of airflow from top to bottom, and as the height of the tower lengthens, the kinetic energy enhances and subsequently increases the overall efficiency of the tower. An elevation about 2.7% in airflow velocity was seen due to an increase from 180 to 250cm in chimney height. Although the energy tower performs efficiently in the nighttime, airflow velocity increases averagely about 8% during the daytime and at the peak of the solar radiation, the airflow velocity enhances by 58% compared to nighttime.

Wind and solar energy potential in Herkalou and Lake Assal locations, Djibouti

The absence of meteorological data to identify the energy resources and the available energy potential represented a major obstacle in some areas in Djibouti. To solve this data problem, in this paper, wind and solar potential were assessed by collecting daily and monthly wind and solar data for the period from 1 January to 31 December 2020, for Herkalou and Lake Assal site. This study highlights that the wind resources in the Lake Assal location are falling into class 7 with high wind speed value of 16 m.s<sup>-1</sup> and the wind energy reaching1700 kWh/m<sup>2</sup> at 100 m height above ground level. While the Herkalou site shows a lower potential with value of 7.5 m.s<sup>-1 </sup>and 160 kWh/m<sup>2</sup>. The solar potential shows a similar distribution and a constantly high level of solar radiation throughout the year, with the monthly maximum global radiation peaks of around 900 W/m² between 11.00 and 14.00 pm for both sites. The highest monthly average of global solar irradiation values was 5.29 kWh/m<sup>2</sup> day<sup>-1 </sup>and 6.90 kWh/m<sup>2</sup> day<sup>-1 </sup>in March for Herkalou and Lake Assal, respectively. Results obtained in this study are favorable to deploying the solar and wind technologies for the studied sites.

Intense nonlinear laser field longitudinal vector potential breaks motion symmetry of stimulated electron and produces highly collimated radiation

The effects of longitudinal fields on electron dynamics, power, and radiation spectrum in tightly-focused circularly polarized laser pulses are investigated in detail. When the longitudinal field vector potential is not considered at the intense relativistic laser field, the longitudinal acceleration of the electron subjected to the ponderomotive force is oscillatory, and the electron will be pushed out of the laser field. The peak radiation power, along with peak angle, varies exponentially with the laser peak amplitude. The longitudinal field leads to the appearance of spatial radiation vortex states when the laser peak is strong, increasing the collimation of the power and spectrum of spatial radiation as well as the focus.

Study and Analysis of UFMC Technology in 5G Communications

Wireless communication technology plays a significant role in the development of mobile technology. Every user requires their own spectrum. However, spectrum bands are limited. Therefore, the communication system must be efficient. This paper discusses the Universal Filtered Multi-Carrier (UFMC) technology, a new promising technology intended to improve mobile networks in the future. This technology is less susceptible to estimate errors of time shifts and frequency shifts. 5G’s major goals are speed, low latency, Quality of Service, and channel capacity. Physical layer waveform generation must be flexible in order to meet these requirements. Currently, 4G-LTE transmissions are not compatible with 5G technologies because of Out of Band radiation and high Peak to Average Power Ratio (PAPR). A future cellular network could benefit from UFMC. The performance of UFMC is evaluated using Power Spectral Density, PAPR, Signal-to-Noise Ratio, and Bit Error Ratio for 5G wireless communications. It is possible that UFMC will be more efficient and gives better solution.

A Novel Integrated UWB Sensing and 8-Element MIMO Communication Cognitive Radio Antenna System

In this article, a cognitive radio (CR) integrated antenna system, which has 1 sensing and 24 communication antennas, is proposed for better spectrum utilization efficiency. In the 24 communication antennas, 3 different operating band antennas are realized with an 8-element MIMO configuration. The sensing antenna linked to port 1 is able to sense the spectrum that ranges from 2 to 12 GHz, whereas the communication 8-element MIMO antennas linked with ports 2 to 9, ports 10 to 17 and ports 18 to 25 perform operations in the 2.17–4.74 GHz, 4.57–8.62 GHz and 8.62–12 GHz bands, respectively. Mutual coupling is found to be less than −12 dB between the antenna elements. Peak gain and radiation efficiency of the sensing antenna are better than 2.25 dBi and 82%, respectively, whereas the peak gains and radiation efficiencies of all communication antennas are more than 2.5 dBi and 90%, respectively. Moreover, diversity characteristics of the MIMO antenna are assessed by parameters such as DG, ECC and CCL. It is found that ECC and CCL are less than 0.42 and 0.46 bits/s/Hz, respectively, and also DG is more than 9.1 dB.

Threshold values for the protection of marine ecosystems from NORM in subsea oil and gas infrastructure

This modelling study uses the ERICA Tool and Bateman's equation to derive sediment threshold values for radiation protection of the marine environment relevant to NORM-contaminated products (radium-contaminated scales, 210Pb films and 210Po films) found in subsea oil and gas infrastructure. Threshold values are calculated as the activity concentration of the NORM-contaminated products' head of chain radionuclide (i.e., 226Ra + 228Ra, 210Pb, or 210Po) that will increase radiation dose rates in sediments by 10 μGy/h to the most exposed organism at a given release time. The minimum threshold value (corresponding to peak radiation dose rates from the ingrowth of progeny) were for radium-contaminated scales, 0.009 Bq/g of 226Ra, 0.029 Bq/g of 228Ra (in the absence of 226Ra) or 0.14 Bq/g of 228Ra (in the presence of 226Ra), followed by 0.015 Bq/g for 210Pb films, and 1.6 Bq/g for 210Po films. These may be used as default threshold values. Added activity concentrations of the NORM-contaminated products to marine sediments below these threshold values implies a low radiological risk to organisms while exceedances imply that further investigation is necessary. Using contaminated product specific parameterisations, such as Kd values derived for Ra from a BaSO4 matrix in seawater, could greatly affect threshold values. Strong consideration should be given to deriving such data as part of specific radiological risk assessments for these products.

Improvement of undulator radiation intensity using edge radiation

The intensification of undulator radiation caused by the application of edge radiation due to a relativistic electron passing through a straight section is analytically and numerically investigated. Here, the modification of the undulator orbit shape of the cosine wave function to a triangular wave function is shown to increase the peak radiation for an undulator. The principle of the intensification effect is based on the superimposition of the edge radiation field from tilted straight sections, which create the triangular wave orbit. The tilt angles for the straight sections have values of rad for the longitudinal axis of the undulator, where is a relativistic factor. The longitudinal length of a straight section has a value of for a radiation wavelength Using a simple model, an analytical equation for the radiation intensity for an undulator with a triangular orbit is derived. The results obtained using the equation are in agreement with those obtained using a numerical radiation code. The peak radiation intensity is estimated to be about two times larger than that of an ordinary planar undulator with K = 1 and the same longitudinal length.

Oxygen Saturation Monitor Model Design for Freediving Implementation

This paper describes the operation model of reflectance oxygen saturation monitor for freediving implementation and its dependence on distance and interposing media between the monitor and human skin. The model includes two LEDs with peak radiation wavelengths 660 nm and 940 nm and two photodiodes with peak sensitivity at 940 nm, interposing medium layer with air, water or silica glass parameters and seven skin layers. The modeling is executed by Monte-Carlo method for the cases of air, glass and water as interposing medium and its various width in range from 2 mm to 8 mm which is chosen due to the planned case construction. The energy fluxes ratio dependence on distance between the photodiodes and skin is evaluated and analyzed.

A 200 MHz to 850 MHz VHF/UHF Antenna for Local Area Cognitive Radio Networks Applications

Cognitive Radio Networks (CRN) support the optimal usage of licensed vacant spectrum using interviewing and underlay techniques. The aim of this work is to design a Very High Frequency (VHF) and Ultra High Frequency (UHF) range wideband antenna between 200 MHz and 850 MHz for CRN application. Antenna fabrication was done using FR4 substrate which measures a dimension of 108 mm x 108 mm. The underutilized spectrum in the range is effectively utilized by the cognitive user in the absence of a licensed primary user. This is achieved by the spectrum sensing technique by sensing the user environment. Therefore the necessity of spectrum sensing antenna is determined by this work and the same is achieved through meticulous design and extensive testing. The simulated and measured results are well in agreement and achieve wide bandwidth of 650MHz with a peak radiation efficiency of 96%.

Th-Shaped Tunable Multi-Band Antenna for Modern Wireless Applications

A compact, reconfigurable antenna supporting multiple wireless services with a minimum number of switches is found lacking in literature and the same became the focus and outcome of this work. It was achieved by designing a Th-Shaped frequency reconfigurable multi-band microstrip planar antenna, based on use of a single switch within the radiating structure of the antenna. Three frequency bands (i.e., 2007–2501 MHz, 3660–3983 MHz and 9341–1046 MHz) can be operated with the switch in the ON switch state. In the OFF state of the switch, the antenna operates within the 2577–3280 MHz and 9379–1033 MHz Bands. The proposed antenna shows an acceptable input impedance match with Voltage Standing Wave Ratio (VSWR) less than 1.2. The peak radiation efficiency of the antenna is 82%. A reasonable gain is obtained from 1.22 to 3.31 dB within the operating bands is achieved. The proposed antenna supports Universal Mobile Telecommunication System (UMTS)-1920 to 2170 MHz, Worldwide Interoperability and Microwave Access (WiMAX)/Wireless Broadband/(Long Term Evolution) LTE2500–2500 to 2690 MHz, Fifth Generation (5G)-2500/3500 MHz, Wireless Fidelity (Wi-Fi)/ Bluetooth-2400 to 2480 MHz, and Satellite communication applications in X-Band-8000 to 12000 MHz. The overall planar dimension of the proposed antenna is 40 × 20 mm2. The antenna was designed, along with the parametric study, using Electromagnetic (EM) simulation tool. The antenna prototype is fabricated for experimental validation with the simulated results. The proposed antenna is low profile, tunable, lightweight, cheap to fabricate and highly efficient and hence is deemed suitable for use in modern wireless communication electronic devices.

Radiation of extreme ultraviolet source and out-of-band from laser-irradiated low-density SnO<sub>2</sub> target

The extreme ultraviolet (EUV) lithography technology required for high-end chip manufacturing is the first of 35 “bottleneck” key technologies that China is facing currently. The high conversion efficiency EUV source and low out-of-band radiation play a significant role in the application of the EUV lithography system. In this work, the EUV source and out-of-band radiation are studied by using laser irradiated solid Sn target and low-density SnO<sub>2</sub> target. The result shows that a strong EUV radiation at a wavelength of 13.5 nm is generated when the laser irradiates the two forms of Sn targets. Owing to the self-absorption effect of the solid Sn target plasma, the maximum intensity of the wavelength is not located at the position of 13.5 nm, which is working wavelength of EUV lithography system. However, the peak radiation spectrum is located at the position of 13.5 nm with low-density SnO<sub>2</sub> target due to its weaker plasma self-absorption effect. In addition, the satellite lines are weaker in low-density SnO<sub>2</sub> target than in the solid Sn target, so that the spectrum efficiency of the EUV at 13.5 nm (2% bandwidth) is increased by about 20%. On the other hand, the experimental study of the out-of-band radiation is carried out. The out-of-band radiation spectral results show that the out-of-band radiation is mainly dominated by the continuum spectrum. Compared with the solid Sn target, the low-density SnO<sub>2</sub> target contains a part of the low <i>Z</i> element O (<i>Z</i> = 8), resulting in a low-intensity continuum spectrum. In addition, the collision probability of ion-ion and electron-ion both become low when the laser irradiates the low-density SnO<sub>2</sub> target, resulting in a short out-of-band radiation duration time. Therefore, the out-of-band radiation generated by the laser irradiated on the low-density SnO<sub>2</sub> target is weak based on the above reasons. The angular distribution of out-of-band radiation measurement results shows that the intensity of out-of-band radiation decreases with the angle increasing. A cosine function <inline-formula><tex-math id="M2">\begin{document}$A \cos ^\alpha \theta$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20222385_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20222385_M2.png"/></alternatives></inline-formula> can fit the angular distribution of the total radiation.

Investigation of radiation response on pure silica large core fibers at low dose levels

The radiation responses of three large core silica fibers with low OH contents were investigated with a high Dose rate (105 Gy/s), low total dose (1 mGy) pulsed X-rays, and low Dose rate (0.054 Gy/s) steady state gamma rays, respectively, to develop a fast radiation detector based on silica fiber and scintillator. The radiation-induced emission (RIE) and radiation-induced attenuation (RIA) of these fibers from a 350 nm–550 nm spectrum range were evaluated. All of them presented low RIA levels, and the Cherenkov radiation and individual peak fluorescence emission centered at 460 nm, being the primary contributors to RIE. In addition, the spectral decomposition of RIAs is performed using known Gaussian absorption bands associated with a few point defects; such as Si-related defects (Non-bridging-oxygen hole center-NBOHC, Si-ODC(II) Self-trapped hole-STH), and chlorine related defects (Cl0 and Cl2). The performances of these point defects at various irradiation doses are analyzed.