Search

Malignant pleural mesothelioma (MPM) is a rare tumor with poor prognosis and rising incidence. Palliative care is common in MPM as radical treatment with curative intent is often not possible due to metastasis or extensive locoregional involvement. Numerous therapeutic advances have been made in recent years, including the use of less aggressive surgical techniques associated with lower morbidity and mortality (e.g., pleurectomy/decortication), technological advancements in the field of radiotherapy (intensity-modulated radiotherapy, image-guided radiotherapy, stereotactic body radiotherapy, proton therapy), and developments in systemic therapies (chemotherapy and immunotherapy). These improvements have had as yet only a modest effect on local control and survival. Advances in the management of MPM and standardization of care are hampered by the evidence to date, limited by high heterogeneity among studies and small sample sizes. In this clinical guideline prepared by the oncological group for the study of lung cancer of the Spanish Society of Radiation Oncology, we review clinical, histologic, and therapeutic aspects of MPM, with a particular focus on all aspects relating to radiotherapy, including the current evidence base, associations with chemotherapy and surgery, treatment volumes and planning, technological advances, and reradiation. Sin financiación No data 2021 UEM

The systems intended for detecting objects of artificial and natural origin are widely used while implementing the remote sensing methods. In this case, such different frequency ranges of sounding signals as radar, acoustic and optical ones are used. This article presents the results of patent analysis of the detection systems for such groups of the International Patent Classification as G01S13, G01S15, G01S17. The analysis has been carried out using the database of the United States Patent and Trademark Office (USPTO) inventions registered from 2015 to 2019. The aim of the given study was to compare the development trends of the object detection systems using the reflection or reradiation of radio-, acoustic or electromagnetic waves. It is shown that the proposed approach makes it possible to identify the promising (breakthrough) technological directions, as well as to form predictive estimates of their development in the short-term.

A series of experiments were conducted in the 3.6-s microgravity drop tower and normal gravity to investigate the effect of solid fuel curvature, conduction, and reradiation on the flame extinction of spherical polymethyl methacrylate (PMMA). In the semi-quiescent microgravity environment, flame extinction was observed if the PMMA diameter was larger than 40 mm, because of a smaller flame conductive heating in larger diameter (i.e., the curvature effect). Compared to the droplet combustion with a low evaporation point and fast heat convection in the liquid phase, the solid fuel has a high pyrolysis point and large transient heat conduction. Thus, the large surface reradiation effectively cools down the fuel surface to promote extinction. Also, as the initial burning duration increases, the conductive cooling into the solid fuel decreases, which delays or prevents the flame extinction in microgravity. The extinction criterion for microgravity flame is explained by the critical mass flux and mass-transfer number. This work helps to understand the curvature effect of solid fuel on flame extinction and the material fire safety in the microgravity spacecraft environment.

Application of parabolic dish collector systems working in a range of low/medium temperatures is of great importance in industrial practice. In this work, a thermal efficiency analysis will be performed for different receivers such as a flat-plate receiver and a cavity receiver (with and without a glass cover). Most of the previous receivers analyses found in the literature have been performed for applications with high temperatures. Moreover, a detailed analysis including losses such as reradiation, natural and forced convection, and conduction, have been performed, developing new correlations for natural and forced convention. The obtained results are discussed in detail, obtaining a significant increasing of efficiency of the cavity receivers against the flat-plat receiver with much less working temperatures: up to 20 % for the covered cavity receiver in comparison with the flat-plate receiver, with a temperature reduction at the receiver of more than 450 ° C .

Linear periodically time-varying (LPTV) circuits are finding increased prominence in reconfigurable transceiver applications. Impedance matching of such circuits to the antenna impedance is essential for fully on-chip receiver topologies. However, deriving the $S_{11}$ of an LPTV circuit is non-trivial in general. Moreover, reflections at harmonic offsets from input frequencies can also be expected due to the time-varying nature of the circuit. This paper utilizes the conversion matrix-based analysis technique to compute the $S_{11}$ of a general LPTV circuit. Furthermore, it is shown that signal reradiation at harmonic shifts from input frequencies is also obtained as a natural consequence of this analysis. Examples related to mixer-first receivers, switched-capacitor receiver front-ends (with reset), and Filtering-by-Aliasing (FA)-based receivers are considered to verify the analysis. Design guidelines are provided to attain optimal $S_{11}$ in a few such scenarios. Explicit analytical expressions are derived for reradiation in ideal $N$ -path mixer-first receivers and FA-based receivers, while guidelines are provided for proper choice of conversion matrix expressions/sizes in case of numerical computation.

Accurately acquiring and analyzing the dynamic radar cross-section (RCS) of wind turbine have a great significance to solve the reradiation interference between wind farms and radar stations. Since the results of high-frequency approximation algorithm are only applicable to the qualitative analysis of electromagnetic scattering, it is almost impossible to accurately acquire the dynamic RCS of wind turbine in actual engineering cases. To this end, we proposed to acquire the dynamic RCS of wind turbine based on the scaled model experimental measurement in a large anechoic chamber. The key techniques of setting up the scaled model as well as the experimental platform were described based on the principle of electromagnetic similarity. The accuracy of experimental result is verified by the comparison with numerical calculation and full-sized experiment reported in literature. By using the control variable method, we were able to measure and analyze the amplitude and phase variation of dynamic RCS with frequency, azimuth, and rotational speed, and achieved the transformation of RCS data into engineering practice. This not only lays a foundation for solving the reradiation interference between wind farms and radar stations, but also provides data support for subsequent theoretical research.

This study presents an efficient and reliable approach to rapidly estimate the scattering properties of chaff particles. This approach adopts the sequential loading method (SLM) which is an iterative post-processing technique that is capable of predicting the new solution of different chaff particles without having to reuse any expensive computational electromagnetic (CEM) tools. The SLM operates solely on the initial solution of a single chaff particle for which the admittance matrix is previously calculated, only once, via the moment method. The calculation of the spatially averaged radar cross section (RCS) of the chaff particles contained in the RR-129 cartridge is successfully obtained by including both reradiation and conductive power losses. Also, a comparison between the estimated results and measured ones is attempted for a single chaff particle of length 5.08 cm.

Solving the reradiation interference level of power lines has problems such as complicated and difficult calculations at short-wave frequency(SF), so it was difficult to research the influence factors of reradiation interference resonance(RIR) at SF. In order to obtain the decisive impact factors of reradiation interference resonance for power lines at SF, various factors that may affect interference are considered, such as tower spans, number of towers, wires, and other single macroscopic structures. Finally, gray system theory and correlation analysis was used to calculate the correlation degree of various impact factors to the interference. The results show that the decisive impact factor of RIR at SF is tower spans, which can be adjusted to avoid the resonance frequency at the line design stage.

The new antenna makes the scattering field of the shared tower more complicated, and the discontinuous scatterers have a coupling effect under multiple excitation sources, which leads to changes in the boundary conditions used to derive the electric field integral equation in the traditional transmission line passive interference solving algorithm. For this reason, based on the generation mechanism of the passive interference scattering field of the transmission line, this paper considers the coupling effect between discontinuous electromagnetic scatterers, and proposes an improved method for solving the passive interference level of the shared tower based on the LE-PO algorithm. Based on the reciprocity theorem and the principle of equivalence, the boundary conditions after the second-order coupling scattering of the shared iron tower scatterer are derived, and the equivalent sources of the scatterers in the mutual coupling background are obtained. The source performs integral solution to obtain the scattered field of the shared iron tower, and finally realizes the accurate solution of the passive interference level. The experimental verification of a single antenna and a single iron column in an anechoic chamber shows that the error of the passive interference solution method considering the coupling is 2.62%, while the error of the traditional LE-PO algorithm is 9.85%.

BACKGROUND Patients who have been treated with reirradiation for recurrent glioma reported survival benefits. Limited data are available for the outcomes after fractionated re-irradiation. This study aims to investigate whether re-irradiation of recurrent glioma with 45Gy dose can increase the overall survival of patients. MATERIAL AND METHODS A retrospective analysis of 35 patients re-irradiated for high-grade glioma recurrence between 2012 and 2020 was performed. All included patients met the following criteria: a) histopathological confirmation of primary brain cancer at initial diagnosis; b) a history of initial primary radiation; c) histological and/or imaging modality confirmation of recurrence. Outcome metrics included overall survival, prognostic factors for survival, and treatment-related toxicity. RESULTS After the end of re-irradiation the median overall survival was 11 months (95% confidence interval, 7–14 months). From the patients evaluated in the current study after the end of re-irradiation the progression free survival was 6 months (3.8 - 8 months) while after the end of first radiation was 13 months (8 - 17.9 months). Our findings suggest that re-irradiation might prolong survival rates. CONCLUSION Recurrent Glioblastoma WHO IV is associated with a median overall survival of less than a year and the majority of patients have profound tumor-related symptoms.The results of this study suggest that re-irradiation may prolong the overall survival.

To identify the promising (breakthrough) trends in the advancement of radio electronic systems with the use of US Patents and Trademark Office database this paper examines the possibilities of patent analysis. This method is based on automatic time series generation of US patents for inventions and subsequent comparison of different technical solutions in specific International Patent Classification subgroups, and in their issuance dynamics for 2007-2017. In particular, the authors analyze several promising trends in the advancement of radio electronic systems using the reflection or secondary radiation of radio waves. The data obtained allow stating that the most promising are systems using the reflection of radio waves and systems adapted for specific applications. According to the authors, the most promising systems, which use the reflection of radio waves, are systems intended solely for measuring distance using transmission of continuous unmodulated waves, amplitude-, frequency- or phase-modulated waves. Radar or analogous systems specially adapted for terrain-avoidance were found to be the most promising among systems for specific applications.

Rooftop solar thermal collectors have the potential to meet residential heating demands if deployed efficiently at low solar irradiance (i.e., 1 sun). The efficiency of solar thermal collectors depends on their ability to absorb incoming solar energy and minimize thermal losses. Most techniques utilize a vacuum gap between the solar absorber and the surroundings to eliminate conduction and convection losses, in combination with surface coatings to minimize reradiation losses. Here, we present an alternative approach that operates at atmospheric pressure with simple, black, absorbing surfaces. Silica based aerogels coated on black surfaces have the potential to act as simple and inexpensive solar thermal collectors because of their high transmission to solar radiation and low transmission to thermal radiation. To demonstrate their heat-trapping properties, we fabricated tetramethyl orthosilicate-based silica aerogels. A hydrophilic aerogel with a thickness of 1 cm exhibited a solar-averaged transmission of 76% and thermally averaged transmission of ≈1% (at 100 °C). To minimize unwanted solar absorption by O-H groups, we functionalized the aerogel to be hydrophobic, resulting in a solar-averaged transmission of 88%. To provide a deeper understanding of the link between aerogel properties and overall efficiency, we developed a coupled radiative-conductive heat transfer model and used it to predict solar thermal performance. Instantaneous solar thermal efficiencies approaching 55% at 1 sun and 80 °C were predicted. This study sheds light on the applicability of silica aerogels on black coatings for solar thermal collectors and offers design priorities for next-generation solar thermal aerogels.

Theoretical and practical aspects of applying time reversal of elastic waves to localize a source of oscillations or a defect are considered in problems of active ultrasonic monitoring of thin-walled metal structures. Backward reradiation of a time-reversed signal is implemented using a computer model based on a semianalytical integral approach. The proposed algorithm is verified experimentally on aluminum samples excited by piezoelectric wafer active sensors. The results corroborate the possibility of reliably determining of the position and size of the load application region and a local inhomogeneity with a relatively small number of signal measurement points on the sample surface.

The physical processes associated with deep welding are analyzed. A two-dimensional numerical model is proposed for the interaction of the laser beam with the medium in the vapor channel. The following processes are considered: heat and mass transfer; absorption and reradiation of the beam’s energy by the plasma; interaction of the plasma with the channel walls; and heat transfer to the cold sample. The model establishes a quantitative relation between the welding conditions and the results of butt welding. That decreases the expenditures in the development of laser-welding processes.

Air-coupled ultrasound (ACU) is increasingly used for nondestructive testing (NDT). With ACU, no contact or coupling agent (e.g., water and ultrasound gel) is needed between transducers and test sample, which provides high measurement reproducibility. However, for testing in production, a minimum separation is often necessary between the sample and the transducers to avoid contamination or transducer damage. Due to wave diffraction, the collimation of the ultrasound beam decreases for larger propagation distances, and ACU images become blurred and show lower defect lateral resolution with increasing sample–transducer separation. This is especially critical to thick composites, where large-size planar sources are used to bridge the large ACU transmission loss with good collimation. In this work, ACU reradiation in unbounded media is extended to NDT of multilayered composites. The extended method is named ACU time reversal (ACU-TR) and significantly improves the defect resolution of ACU imaging. With ACU-TR, the complete pressure distribution radiated by large ACU source is measured with point receivers (RXs) in one plane arbitrarily separated from the sample. By applying acoustic holography physics, it is then possible to quantitatively reconstruct the pressure field directly at arbitrary sample defect planes, which compensates for undesired diffraction phenomena and improves minimum detectable defect size, thereby achieving subwavelength lateral resolution. We tested the method on complex wood-based composite samples based on the ACU far-field measurements at a separation of 160 mm between the sample and the RX transducer. With the proposed method, it is possible to detect surface defects as well as inner defects within composite boards. In the future, by using point RX arrays instead of a scanned microphone, both data acquisition and evaluation can be potentially implemented in real time.

We present a subwavelength-thick reflection-less metamaterial absorber that shows frequency-selective narrow-band near-perfect absorption at 2.4 GHz. The absorber does not have a ground plane and is constructed with a square array of pairs of C-shaped split-ring resonators (SRRs) orthogonally arranged in such a way that induced electric and magnetic dipoles destructively interfere and no reradiation of electromagnetic (EM) waves is observed. The SRRs are made of nichrome with high ohmic loss so that EM energy dissipates as heat. We numerically determined the optimum geometrical parameters of SRRs, and absorption of 97% is achieved at 2.4 GHz. We also fabricated a device using nichrome wire and obtained a huge decrease in transmission at a resonance of –6 dB with no reflection over the entire frequency range of interest. Our basic concept can be extended to higher frequency ranges and may be utilized for next-generation wireless communications, the Internet of Things (IoT), and so forth.

This article aims to practically assess the point scatterer formulation to characterize the electromagnetic behavior of ornamental plants with varying thickness at 60 GHz. The proposed propagation model uses various point scatterers with specific radiation characteristics, distributed within a computational area, to describe the effect of the plants present in the radiowave propagation path. Additionally, a ray-tracing-based engine is used to gather all the interactions between the point scatterers present in the simulation channel. The performance of the proposed modeling approach is assessed against reradiation measurements of single and isolated plants, performed in the 60-GHz frequency band, inside an anechoic chamber. Additional model validation is obtained from reradiation measurements of several clumps of plants, mimicking specimens with varying thickness.

A high-frequency asymptotic method has been applied to formulate E-polarized plane wave diffraction by a thick slit. The slit structure is regarded as an open-ended parallel plane waveguide cavity, and the excitation of the waveguide modes and their reradiation are derived from a ray-mode conversion technique. Comparison with another method reveals the validity and effectiveness of our formulation.

IEEE was not able to give the resonance mechanism of reradiation interference (RRI) above 1.7 MHz from power lines based on research works of electric field. In order to solve this problem, the generalized resonance theory is introduced, and a method based on the electromagnetic (EM) energy balance theory is proposed to predict the RRI resonant frequency. Taking a large-scale space including UHV power lines and antenna arrays as a generalized closed system, the expression of EM open systems' generalized resonance factor is derived based on the complex Poynting theorem. Then the RRI resonant frequency corresponds to the zero point of the generalized resonance factor's imaginary part. Taking the case researched by IEEE as an example, the maximum deviation of the resonant frequency between the values predicted by the generalized resonance theory and the measurement values obtained from scaled model experiments are less than ±0.169 MHz in the frequency band below 1.7 MHz.

Little research has examined that inaccurate estimations of directional emissivity form a major challenge during both passive and active thermographic measurements. Especially with the increasing use of complex curved shapes and the growing precision of thermal cameras, these errors limit the accuracy of the thermal measurements. In this work we developed a technique to estimate the directional emissivity using updated numerical simulations. The reradiation on concave surfaces is examined by thermal imaging of a homogeneous heated curved metal and nylon test sample. We used finite element modelling to predict the reradiation of concave structures in order to calculate the parameters of an approximating formula for the emissivity dependent on the angle to the normal vector on each element. The differences between experimental and numerical results of the steel test sample are explained using electron microscopy imaging and the validation on different materials. The results suggest that it is possible to determine the errors of thermal imaging testing of complex shapes using a numerical model.

Analytical models addressing ignition of solids under constant heat flux have been developed in previous studies utilizing surface or in-depth absorption or combination of them. When encountering time-dependent heat flux, the majority of the studies focused on polynomial heat flux and surface absorption assumption. However, in-depth absorption also should be taken into account under time-dependent heat flux in analytical models especially for infrared translucent solids. In this work, an analytical model aiming at revealing the ignition mechanism of translucent polymers under exponential time-increasing heat flux is established considering both surface and in-depth absorptions. Critical temperature is employed as ignition criterion. Four typical non-charring polymers, polymethyl methacrylate (PMMA), polyoxymethylene (POM), polyamide 6 (PA 6) and polypropylene (PP), are utilized as the reference materials, and a numerical solver is employed to validate the analytical model. The results show that the developed analytical model provides accurate predictions of surface temperature and ignition time. Surface heat loss by convection and reradiation has little effect on surface temperature, ignition time and critical energy, but it affects the ignition heat flux greatly. Thermal penetration depth differs from the one under constant heat flux, and it gets smaller as the surface heat loss is considered. The ignition time, thermal penetration depth and critical energy decrease as the heat flux increasing rate gets larger. Meanwhile, the ignition heat flux for in-depth absorption is higher than that for surface absorption, and both increase with heat flux increasing rate. Furthermore, the linearity between ignition time and the squared critical energy, proposed in constant and linear heat flux scenarios, is also found valid under this exponential heat flux condition.

The explosive growth of the data traffic in future satellite communications can be leveraged by exploiting higher unlicensed spectrum band. In particular, Terahertz (THz) communication has been considered as a promising solution, since it can provide tens of GHz bandwidth. In addition, massive multiple input multiple output (MIMO) with a very large antenna array can be used in THz communications to provide large array gain to compensate for severe signal attenuation. To this end, this paper analyzes a terahertz MIMO channel modeling and simulation method for massive antenna array based satellite-ground communications. Taking into account the molecular absorption noise, transmission path loss, and molecular reradiation effects of the terahertz channels under a variety of typical weather models, we evaluate the bit error rates (BERs) for different frequencies, communication distances and signal strengths. Numerical results validate the feasibility of the proposed modeling approach.

We propose a new direction-of-arrival (DoA) method for wireless power transfer (WPT) by utilizing harmonic reradiation from rectenna. A feature of the proposed method is needlessness of a pilot signal oscillator in the receiving site, then the receiving system can be configured without any power supplies and batteries. We developed and experimentally investigated the harmonic-reradiated DoA estimation system. We verified that the measurement results were comparable with a conventional DoA estimation and simulation results, except for the interference with the direct incoming waves from the WPT transmitter. We discussed error factors from viewpoints of mutual coupling effects on receiving antennas, and asymmetric property of the receiving antennas including feeding points, as well as the interference with the WPT transmitter. By calibrating the measured data, the harmonic-reradiated DoA estimation errors were mitigated within the range from -2.1° to 3.5°.

In this paper, a circular sector antenna pair with harmonic rejection property for wireless power transmission (WPT) by near-field coupling is proposed. This antenna pair is adopted the coupled resonant method which can mutually compensate the impedance mismatching in the near field. When the transmitting antenna removes from the receiving antenna, the receiving antenna can also resonant independently and function as an antenna for Wi-Fi or energy harvesting. To improve the conversion efficiency, the circular sector antenna pair which can suppress re-radiation of the higher order harmonics to free space and reduce power loss due to the reradiation is adopted as the transmitting-receiving antenna. The conversion efficiency of the circular sector antenna pair is 80% when the input RF power is 19 dBm.

Modeling vegetation usually implies obtaining experimental data by means of measurement campaigns. In general, the most accurate models need the reradiation pattern of the vegetation volume under study, or some of its related parameters. Obtaining this function might not be easy, and the measurement procedure may introduce errors depending on the location of the vegetation mass. An accurate tool to simplify this process is presented, based on the ability of artificial neural networks to infer behavioral patterns. This proposal reduces the acquisition of the experimental data to a scarce set of angles around the tree or bush, which will then be used to train a neural network capable of retrieving the desired reradiation function desired.

Due to their complex and inhomogeneous characteristics, the propagation and radiation parameters of trees and vegetation areas are very difficult and time consuming to obtain. This communication proposes a statistical method, using robust weighted local regression, to minimize the influence of the effect of the tree inhomogeneity on its reradiation pattern, allowing the evaluation of averaged reradiation functions from simple measurements. The proposed method was successfully applied to six tree specimens of both conifer and ficus species, at 60 GHz. Furthermore, once this empirical averaged function is obtained, first-order statistics can be applied to generate several simple reradiation functions, statistically identical to those obtained from measurements. Thus, allowing the full characterization of the tree under study.

In the case of low wind-induced waves the surface irregularities of troughs between sea waves ridges are located outside of the deep shadowing region with respect to the corresponding points and it is necessary to estimate their role in the field forming at the receiving point. The analysis has demonstrated that under these conditions there may occur a multiple interaction of the irradiating field with the irregularities of underlying surface. The analysis is limited by the account of double interaction due to the significant magnitude reduction for each reradiation of the secondary wave with respect to the original one. It this paper we propose to estimate its influence using the technique of comparison of the received signal characteristics, which have been obtained by taking into account the double interaction and without it.The characteristics are obtained by the simulation of the electromagnetic field propagation in the case of low wind-induced waves in the context of Kirchhoff approximation using the secondary Huygens sources principle.

Using the process model, we describe the phase, amplitude, polarization, and spatial characteristics of the parametric scatterer. The mathematical model of the parametric scatterer, which is developed on the basis of its equivalent circuit, is also discussed. The relation between the parameters of the process and mathematical models of the parametric scatterer is shown. The transient processes during simultaneous action of the pump- and synchronization-signal radio pulses on the parametric scatterer are studied. We show that it is expedient to use the synchronization radio pulse at the reply-signal frequency not only for disambiguation of the initial phase of the reply signal, but also for quick excitation of the parametric circuit.

This paper presents a feasibility study on extending the applicability of the discrete radiative energy transfer (dRET) model to the trunk layer of raised canopy forests. The framework herein presented, proposes a method to predict the scattered signal inside and around a formation of cylinders (mimicking thin tree trunks), which is based on the prior knowledge of the cylinder 2-D reradiation pattern as input parameters to the dRET model. The characterization and modeling of the cylinder 2-D reradiation patterns were performed in an anechoic chamber, so that frequency-dependent effects could be evaluated. The assessment of the proposed method was performed against measurements within a formation of both metallic and dielectric cylinders mimicking thin tree trunks, at micro- and millimeter-wave frequencies, i.e., 9.4, 18.8, and 37.6 GHz.

The resonant mechanism of reradiation interference (RRI) over 1.7MHz from power transmission lines cannot be obtained from IEEE standards, which are based on researches of field intensity. Hence, the resonance is ignored in National Standards of protecting distance between UHV power lines and radio stations in China, which would result in an excessive redundancy of protecting distance. Therefore, based on the generalized resonance theory, we proposed the idea of applying model-based parameter estimation (MBPE) to estimate the generalized resonance frequency of electrically large scattering objects. We also deduced equation expressions of the generalized resonance frequency and its quality factor Q in a lossy open electromagnetic system, i.e. an antennatransmission line system in this paper. Taking the frequency band studied by IEEE and the frequency band over 1.7 MHz as object, we established three models of the RRI from transmission lines, namely the simplified line model, the tower line model considering cross arms and the line-surface mixed model. With the models, we calculated the scattering field of sampling points with equal intervals using method of moments, and then inferred expressions of Pade rational function. After calculating the zero-pole points of the Pade rational function, we eventually got the estimation of the RRI’s generalized resonant frequency. Our case studies indicate that the proposed estimation method is effective for predicting the generalized resonant frequency of RRI in medium frequency (MF, 0.3~3 MHz) band over 1.7 MHz, which expands the frequency band studied by IEEE.

The impact of the reflection of fire-induced heat from a gas burner was studied experimentally to gain knowledge on the interaction between photovoltaic (PV) panels and a fire. The heat flux was measured in a total of eight points at the same level as the top of the gas burner. The gas burner was placed underneath the centre of a PV panel and the eight points were measured in symmetrical pairs of two at four different distances from the burner. The heat release rate from the gas burner was increased stepwise every four minutes. The measurements were made underneath a PV panel installed in a geometry similar to a commercial East-West orientated mounting system and was compared to a baseline test without the re-reflection from the PV panel. A significant increase of the received heat flux was noticed and the trend indicated an ascending percentage-wise difference as a function of an increased heat release rate. Contrary to the basic view factor theory, the received heat flux was higher underneath the most elevated part of the PV panel, and this occurred due to two important flame related reasons: 1) the deflection of the flame towards the most elevated part of the panel, resulting in an increased amount of radiation from the flame towards the surface; 2) A non-homogeneous distribution of the temperature on the PV panel surface, due to the deflected flame, and thereby a non-homogeneous emission from the heated PV panel. Finally, it was seen that two similar tests conducted with respectively a brand new PV panel and a PV panel tested for the fourth time, showed very comparable results, except during the period when the thin combustible film underneath the new PV panel was burning. This resulted in a higher heat flux during that period and implies that the results presented herein are conservative in that they are lower than what can be expected in case of a real fire hazard, where the PV panel is by definition involved in the fire for the first time. It can be concluded that PV panels can have a significant contribution in roof fires, as they stimulate fire spread over the roof on which they have been mounted. These findings emphasise that the risk related to the installation of PV panels is not only associated with the increased fire load and possibility of ignition, but largely also with the changed fire dynamic surroundings of the roof construction.

Quantitative and reproducible air-coupled ultrasound (ACU) testing requires characterization of the volumetric pressure fields radiated by ACU probes. In this paper, a closed-form reradiation method combining the Rayleigh–Sommerfeld integral and time-reversal acoustics is proposed, which allows calculation of both near- field and far-field based on a single-plane measurement. The method was validated for both 3-D (circular, square) and 2-D (rectangular) planar transducers in the 50–230 kHz range. The pressure fields were scanned with a calibrated microphone. The measurement window was at least four times the size of the transducer area and the grid step size was one third of the wavelength. Best results were observed by acquiring the measurement plane at near-field distance. The method accurately reproduces pulsed ultrasound waveforms and pressure distributions (RMSE

Nuclear Quadrupole Resonance (NQR), a type of radio frequency spectroscopy, holds the promise of unambiguous detection of particular explosives; the associated resonant frequencies are virtually unique. This specificity is spoiled by natural and anthropogenic interference that can swamp the NQR signal. Fortunately, the spatial magnetic signature from the explosive differs significantly from that of interference and can be exploited to separate the signals. An array of coils, however, cannot provide truly independent measurements due to the inductive coupling between the coils. Single coil configurations can cancel out constant interference and retain the signal from an NQR coil, but the balance between arms of the coil is compromised by differential coupling to the environment. Atomic magnetometers, an emergent technology predicted to surpass the sensitivity of coil detection, do not suffer from such coupling and have no fundamental limitation to forming an array of independent sensors. We have demonstrated up to 94× interference rejection with a 4-sensor array spanning 25 cm. The array symmetry permits rejection of linearly varying interference. We discuss the prevention of reradiation from DC field coils used to set the magnetometer resonance frequency. Such reradiation leads to non-linear variation. The benefits of larger sensor arrays are also explored.

The quasi-superdirective reradiation and in-phase retroreflection are presented for the sake of monostatic radar cross-section enhancement. Two passive structures, including a post-loaded thin plate and a metasurface-coated cylinder, are proposed to demonstrate the validity of the concepts. For the thin plate loaded with posts, it is seen that surface currents with almost equal magnitudes but opposite directions can be induced on the loading two-post with each post height less than a quarter-wavelength. The resultant quasi-superdirective reradiation obviously enhances backscattering of the thin plate at edge-on incidence. Moreover, the design of a conformal gradient metasurface is proposed. It is observed that a polarization-independent enhancement of backscattering can be obtained through the efficient retroreflection produced by a cylinder coated with the designed metasurface. The achieved enhancement of backscattering is at least 10 dB for both designs.

In the construction of UHVDC power line in China, the national standard of reradiation interference protecting distance between UHVDC power line and receiving station of AM broadcasting needs to be renewed. In this paper, the wire-surface simulation model is used to calculate the interference. In the model, steel tower is represented as surface model, ground wire is represented as wire model, and the whole model is excitated by vertical polarization plane wave. For the deficiency of traditional solution method of protecting distance calculation, a new method is proposed. It is recommended that the whole work frequency band of receiving station should be calculated to determine the space interval which has actual protecting distance. Then the interval is gradually narrowed with dichotomy method until the interval size is within allowable value. With the first-grade receiving station of AM broadcasting as example, the reradiation interference protecting distance from UHVDC power line and station is calculated..