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In order to further improve crashworthiness and reduce weight, tailor-welded blanks (TWBs) have been widely applied in auto-body design. In this paper, the discrete optimization design of TWBs structures with top-hat thin-walled section subjected to front dynamic impact is performed by using Taguchi-based gray relational analysis. Material grades and thicknesses with three levels are taken as discrete design variables. The total energy absorption ( EA ), the total weight ( Mass ) and the peak crashing force ( F max ) are chosen as optimization indicators. Considering the uncertain weight ratio of responses, four different cases would be analyzed. In order to determine the optimal parameter combination more accurately and eliminate errors from range analysis, the analysis of variance (ANOVA) would be performed. The optimized results demonstrate that it is feasible to increase the crashworthiness of TWBs by increasing the gray correlation of the structure. Compared to initial structure, case 1 ( w ( F max ): w ( EA ): w ( Mass )= 1/3:1/3:1/3) has the largest improvement among the four cases, i.e., the F max and the Mass are reduced by 29.3% and 2.7%, respectively, while the EA is increased by 3.5%. The discrete optimization method with only 27 iterations is a low computing cost or cost-effective and provides some guidance for some similar structural design. More comprehensive studies are essential to optimize performance of multi-components with more discrete variables. [ABSTRACT FROM AUTHOR]

In this paper, the graybody radiation phenomena has been handled with the help of fractional calculus. Fractional definition of graybody spectrum has been written in terms of Mittag‐Leffler function. The obtained data from fractional calculus approximation for nearly 2.87 × 107 K have been compared with literature values and standard blackbody radiation. [ABSTRACT FROM AUTHOR]

The greybody factor of massless, uncharged scalar fields is studied in the background of cylindrically symmetric spacetimes, in the low-energy approximation. We discuss two cases. In the first case we derive analytical expression for the absorption probability when the spacetime is kinetically coupled with the Einstein tensor. In the second case we do the analysis in the absence of the coupling constant. For this purpose we analyze the wave equation which is obtained from Klein-Gordon equation. The radial part of the wave equation is solved in the form of the hypergeometric function in the near horizon region, whereas in the far region the solution is of the form of Bessel's function. Finally, considering continuity of the wave function we smoothly match the two solutions in the low-energy approximation to get the formula for the absorption probability. [ABSTRACT FROM AUTHOR]

Clinching joint quality and functionality may have undesirable features because of the choice of the forming process parameters. In fact, there are different factors controlling the mechanical connection strength such as the tools' geometry and the joint final shape. This paper presents the implementation of the Taguchi-based Grey optimization of the mechanical clinching with fixed dies for dissimilar materials (Aluminum alloy 7075 and Mild Steel) to derive the optimal process parameters combination that leads to a high strength connection subjected to multiple characteristics, namely, the bottom thickness, the interlock length, and the neck thickness of the joint. LS-DYNA explicit and implicit finite element (FE) software was used to simulate the process in order to evaluate the joint strength by loading the sheets vertically. Taguchi's L27 orthogonal array design and the notion of signal-to-noise (S/N) ratio were utilized to obtain the objective function. Analysis of variance (ANOVA) showed the importance of factors on overall output. The output of the study provided the optimal geometrical parameters of the punch, die, and blank holder. Indeed, the die groove height, die diameter, punch diameter, punch corner radius, and clearance between punch and blank holder were found to be the most influential parameters on the bottom and neck thicknesses. In addition, the output indicated that when bottom thickness or neck thickness increased, the interlock decreased. [ABSTRACT FROM AUTHOR]

In the real world, the observations or statistical data are known as white numbers, but they are grey which means that they deviate from the true values because of disturbances and errors. And this paper applied random simulations to reveal that GM(1,1) mode! can weaken these disturbances or uncertainty. The exponential sequences with different development coefficients and random disturbances are generated randomly, and the sequences are used for GM(1,1) modeling, and then the mean absolute percentage errors (MAPEs) of the modeling are compared and analyzed. It is found that the MAPEs between fitted values and real values are smaller than those between the original values and real values, which shows that GM(1,1) model can weaken uncertainty. [ABSTRACT FROM AUTHOR]

In this paper, a forecasting method for the fluctuating interval number series is proposed. Firstly, the definition equation of GM (1, 1) is improved to suit the interval number series directly and the interval number series needs not to be transformed into real number series. The development coefficient of the definition equation is taken as an accurate number, but the grey input of the definition equation is taken as an interval number. By this method, the binary interval GM (1, 1) (BINGM (1, 1)) is proposed. In order to further make the model fitting to the fluctuating inten'al number series, the support vector machine (SVM) is introduced to amend the predicted results of BINGM (1, 1) and SVMBINGM (1, 1) is proposed. In the process of amendment, the inten'al series is transformed firstly to avoid the disorder of the boundary points of the interval series. The results of the application example show that the prediction accuracy of SVMBINGM (1, 1) is higher than BINGM (1, 1) for the forecasting of fluctuating inten'al series. [ABSTRACT FROM AUTHOR]

Longquan celadon is one of the most valuable treasures in Chinese ceramic history. Representative products are Ge ware (Ge meaning elder brother, black body celadon) and Di ware (Di meaning younger brother, gray body celadon) of the Song Dynasty (960–1279 A.D.). In this study, Ge and Di ware shards excavated from Wayaoyang kiln site in Longquan were collected and studied. Chemical and crystallite composition, microstructure, body and glaze thickness, firing temperature and glaze reflectance spectrum were observed and examined. Differences in raw materials and manufacturing technology between Ge and Di ware were studied. Based on the results and historical background, it was speculated that some Ge wares from Wayaoyang kiln site might be the test products of jade-like black body celadon for the imperial court. [ABSTRACT FROM AUTHOR]

In this paper, we are discussing the problem of low energy greybody factors for fermions emitted by a Schwarzschild-de Sitter (SdS) black hole. In our study, we are using the analytical methods proposed by Unruh some time ago for determining the greybody factors. We have found that at low energies the greybody factors are constant for a given total angular momentum (similar to what happens in the case of scalar particles reported before in the literature). Also, our results are indicating an enhancement in the energy spectrum if one is increasing the value of the cosmological constant. These results are consistent with numerical calculations performed by S. F. Wu et al., Phys. Rev. D 78 (1998) 084010. [ABSTRACT FROM AUTHOR]

Calibration of infrared radiation thermometers at non-unity emissivity settings is a poorly solved problem for establishment of traceability to meet user needs, for instruments with both fixed and variable emissivity setting functions. A variable-temperature gray-body radiator having a constant value of emissivity independent of both wavelength and temperature can be a perfect tool for the calibration purpose. In this paper, two types of high-transmittance optical neutral density filters, one utilizing a rotating-sector optical chopper, and another of a wire-mesh type, are shown to perform well with a precise transmittance between 90 % and 100 % in the wide infrared wavelength range. These optical filters in combination with a blackbody cavity traceable to ITS-90 can realize reliable gray-body radiation. These methods are applied successfully to several models of infrared thermometers operated in the emissivity correction mode. [ABSTRACT FROM AUTHOR]

The paper presents multi-sector stable IR grey body radiation source, that can be used for testing of MRT. Its main element is monolithic metal plate with a test pattern, made of material with high thermal conductivity. On the surface of the test plate the sectors of different emissivity are created during manufacturing process. As a result when viewed by a thermal camera those sectors exhibit thermal contrast depending mainly on the radiative properties of each sector. The value of thermal contrast between particular sectors can be adjusted by changing the temperature of a test plate with respect to ambient. The emissivity values of particular sectors have been calculated and the procedure of adjusting the thermal contrast has been described, as well as the technology used to create the test plate. The model of described emitter has been tested and the results of temperature values obtained from thermal camera were compared with theoretical, calculated figures. The proposed emitter is dedicated for testing and calibrating of modern observations IR systems. [ABSTRACT FROM AUTHOR]

Abstract: Extremization of a weak form for the continuum energy conservation principle differential equation naturally implements fluid convection, radiation and flux Robin boundary conditions associated with unsteady heat transfer. Combining a spatial semi-discretization via finite element trial space basis functions with time-accurate integration for computing. Closure for grey body radiation is a newly derived radiosity formulation generating piecewise discontinuous solutions, while that for natural-forced-mixed convection heat transfer is extracted from the literature. Algorithm performance, mathematically predicted by asymptotic convergence theory, is subsequently validated with data obtained in 24h diurnal field experiments for 1/8’’ and 1’’ thick aluminum plates. [Copyright &y& Elsevier]

Abstract: Emission from sapphire window material was measured by spontaneous spectroscopic and multi-wavelength pyrometer techniques. The spectral distribution as a function of wavelength fit well to the grey-body spectrum. We analyzed the emissions and discovered that they arise from shear banding, which is a typical thermal radiation. It was found that the color temperature of shocked sapphire changes linearly and regularly with stress increases from 40GPa to 59GPa but becomes monotonic for stresses from 87GPa to 120GPa. The change in behavior indicates that a shock-induced phase transformation occurs between 59GPa and 87GPa. [Copyright &y& Elsevier]

The article presents a study which determine the impact of changes on iron content that occur in demyelinating disease to patients with Clinically Isolated Syndrome (CIS). The study uses the ultra-high field magnetic resonance imaging (MRI) to compare 10 CIS patients with 20 age-matched healthy individual. Result shows that there is no consistent trends between susceptibility and age. It concludes that CIS patients showed an increase in iron accumulation considering the deep grey matter.

The (3 + 1) -dimensional Einstein-Gauss-Bonnet theory of gravity which breaks the Lorentz invariance in a theoretically consistent and observationally viable way has been recently suggested by Aoki, Gorji and Mukohyama [5]. Here we calculate grey-body factor for Dirac, electromagnetic and gravitational fields and estimate the intensity of Hawking radiation and lifetime for asymptotically flat black holes in this theory. Positive coupling constant leads to much smaller evaporation rate and longer life-time of a black hole, while the negative one enhances Hawking radiation. The grey-body factors for electromagnetic and Dirac fields are smaller for larger values of the coupling constant. [ABSTRACT FROM AUTHOR]

The Cover Feature shows long‐time exposures of sparks obtained from various elements. The background illustrates gold and silver sparks commonly used in firework compositions based on iron, magnalium (Mg/Al), etc. Gray body radiation dominates the color of these sparks. Exotic elements throughout the periodic table have been investigated to break this limit. We report the first color‐changing sparks based on erbium powder that switch between surface combustion (gray body emission) and gas phase combustion (colorful emission). More information can be found in the Full Paper by E. G. Hübner et al. [ABSTRACT FROM AUTHOR]

We have carried out high-resolution observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) of continuum emission from the Orion Kleinmann–Low (KL) region. We identify 11 compact sources at ALMA band 6 (245 GHz) and band 7 (339 GHz), including the Hot Core, Compact Ridge, SMA1, IRc4, IRc7, and a radio source I (Source I). A spectral energy distribution (SED) of each source is determined by using previous 3 mm continuum emission data. Physical properties such as size, mass, hydrogen number density, and column density are discussed based on the dust graybody SED. Among 11 identified sources, Source I, a massive protostar candidate, is a dominant energy source in Orion KL. We extensively investigate its SED from centimeter to submillimeter wavelengths. The SED of Source I can be fitted with a single power-law index of 1.97, suggesting an optically thick emission. We employ the H− free–free emission as an opacity source of this optically thick emission. The temperature, density, and mass of the circumstellar disk associated with Source I are constrained by the SED of H− free–free emission. Still, the fitting result shows a significant deviation from the observed flux densities. Combined with the thermal dust graybody SED to explain excess emission at higher frequency, a smaller power-law index of 1.60 for the H− free–free emission is obtained in the SED fitting. The power-law index smaller than two would suggest a compact source size or a clumpy structure unresolved with the present study. Future higher resolution observations with ALMA are essential to reveal more detailed spatial structure and physical properties of Source I. [ABSTRACT FROM AUTHOR]