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The fragmentation of light relativistic nuclei can be studied in detail by the technique of nuclear track emulsions. The registration of all charged particles and their identification enable one to explore the isotopic composition of fragments and the projectile fragmentation channels. In the present paper results of an analysis of decay of the 7Be nucleus in dissociation of 8B nuclei are presented and a comparative analysis of the experimental data with the Monte Carlo model calculations is made. The paper is illustrated with characteristic images, obtained by means of a microscope, equipped with a CCD camera. [ABSTRACT FROM AUTHOR]

Risk assessment of debris flow is an uncertain problem involving randomness and fuzziness. The cloud model is used to distinguish for assessing the risk of debris flow scientifically and rationally. Firstly, the system standard of debris flow risk assessment is constructed; secondly, impact factor of each assessment system which belonging to cloud droplet of each risk level produced by normal cloud generator, the subjective weights and objective weights of the debris flow influence factors are coupled by using game theory, and consider the fuzziness of debris flow basic data, using the Monte Carlo modelling thought, and by generating large cloud droplets and statistics of the average value in a mini zone near the basic data for evaluating debris flow as the basic data belonging to some hierarchical average degree of certainty; finally, the proposed model is used for case research, and compared to several existing mature methods to prove the proposed model is feasible and reasonable. [ABSTRACT FROM AUTHOR]

Conducting polymer composites are attractive alternatives for applications such as electromagnetic shielding in which metals are conventionally used. They have unique advantages like light weight, ease of processing and good strength to weight ratio. This makes them economically viable especially in industries like avionics where weight is an important criterion. However, a major challenge in using conducting polymer composites in many of the applications is its limited conductivity. Even though many models exist to describe the conductivity of the composites at the macro level taking into account the interparticle conductivity, very few studies are conducted to understand the conductivity of the composites directly from basic principles. In this study, Monte Carlo (MC) simulations are carried out to study the conductivity in such composites. The results obtained using the MC model showed good agreement with the Mamunya model and the experimental measurements. The effect of various parameters like filler diameter and filler conductivity on the final composite conductivity is studied for spherical and fibrous carbon fillers in silicone rubber. The method can be easily adopted for any other filler–polymer combination and can also be used as a predictive tool for designing simple composites of required electrical properties. [ABSTRACT FROM AUTHOR]

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This paper addresses the influence of land topography and cover on 3D radiative effects under cloudless skies in the Hornsund area, Spitsbergen, Svalbard. The authors used Monte Carlo simulations of solar radiation transfer over a heterogeneous surface to study the impact of a non-uniform surface on: (1) the spatial distribution of irradiance transmittance at the fjord surface under cloudless skies; (2) the spectral shortwave aerosol radiative forcing at the fjord surface; (3) normalized nadir radiance at the Top Of the Atmosphere (TOA) over the fjord. The modelled transmittances and radiances over the fjord are compared to the transmittances and radiances over the open ocean under the same conditions. The dependence of the 3D radiative effects on aerosol optical thickness, aerosol type, surface albedo distribution, solar azimuth and zenith angle and spectral channel is discussed. The analysis was done for channels 3 (459-479 nm) and 2 (841-876 nm) of the MODIS radiometer. In the simulations a flat water surface was assumed. The study shows that snow-covered land surrounding the fjord strongly modifies the radiation environment over the fjord surface. The enhancement of the mean irradiance transmittance over the fjord with respect to the open ocean is up to 0.06 for channel 3. The enhancement exceeds 0.11 in the vicinity of sunlit cliffs. The influence of the snow-covered land on the TOA radiance over the fjord in channel 3 is comparable to the impact of an increase in aerosol optical thickness of over 100%, and in lateral fjords of up to several hundred percent. The increase in TOA radiance is wavelength dependent. These effects may affect retrievals of aerosol optical thickness. [ABSTRACT FROM AUTHOR]

Optical interrogation of suspicious skin lesions is standard care in the management of skin cancer worldwide. Morphological and functional markers of malignancy are often combined to improve expert human diagnostic power. We propose the evaluation of the combination of two independent optical biomarkers of skin tumours concurrently. The morphological modality of reflectance confocal microscopy (RCM) is combined with the functional modality of laser Doppler flowmetry, which is capable of quantifying tissue perfusion. To realize the idea, we propose laser feedback interferometry as an implementation of RCM, which is able to detect the Doppler signal in addition to the confocal reflectance signal. Based on the proposed technique, we study numerical models of skin tissue incorporating two optical biomarkers of malignancy: (i) abnormal red blood cell velocities and concentrations and (ii) anomalous optical properties manifested through tissue confocal reflectance, using Monte Carlo simulation. We also conduct a laboratory experiment on a microfluidic channel containing a dynamic turbid medium, to validate the efficacy of the technique. We quantify the performance of the technique by examining a signal to background ratio (SBR) in both the numerical and experimental models, and it is shown that both simulated and experimental SBRs improve consistently using this technique. This work indicates the feasibility of an optical instrument, which may have a role in enhanced imaging of skin malignancies. [ABSTRACT FROM AUTHOR]

Purpose: On 1 July 2012, the Australian Clinical Dosimetry Service (ACDS) released its Optically Stimulated Luminescent Dosimeter (OSLD) Level I audit, replacing the previous TLD based audit. The aim of this work is to present the results from this new service and the complete uncertainty analysis on which the audit tolerances are based. Methods: The audit release was preceded by a rigorous evaluation of the InLight R nanoDot OSLD system from Landauer (Landauer, Inc., Glenwood, IL). Energy dependence, signal fading from multiple irradiations, batch variation, reader variation, and dose response factors were identified and quantified for each individual OSLD. The detectors are mailed to the facility in small PMMA blocks, based on the design of the existing Radiological Physics Centre audit. Modeling and measurement were used to determine a factor that could convert the dose measured in the PMMA block, to dose in water for the facility's reference conditions. This factor is dependent on the beam spectrum. The TPR20,10 was used as the beam quality index to determine the specific block factor for a beam being audited. The audit tolerance was defined using a rigorous uncertainty calculation. The audit outcome is then determined using a scientifically based two tiered action level approach. Audit outcomes within two standard deviations were defined as Pass (Optimal Level), within three standard deviations as Pass (Action Level), and outside of three standard deviations the outcome is Fail (Out of Tolerance). Results: To-date the ACDS has audited 108 photon beams with TLD and 162 photon beams with OSLD. The TLD audit results had an average deviation from ACDS of 0.0% and a standard deviation of 1.8%. The OSLD audit results had an average deviation of -0.2% and a standard deviation of 1.4%. The relative combined standard uncertainty was calculated to be 1.3% (1s). Pass (Optimal Level) was reduced to =2.6% (2s), and Fail (Out of Tolerance) was reduced to >3.9% (3s) for the new OSLD audit. Previously with the TLD audit the Pass (Optimal Level) and Fail (Out of Tolerance) were set at =4.0% (2s) and >6.0% (3s). Conclusions: The calculated standard uncertainty of 1.3% at one standard deviation is consistent with the measured standard deviation of 1.4% from the audits and confirming the suitability of the uncertainty budget derived audit tolerances. The OSLD audit shows greater accuracy than the previous TLD audit, justifying the reduction in audit tolerances. In the TLD audit, all outcomes were Pass (Optimal Level) suggesting that the tolerances were too conservative. In the OSLD audit 94% of the audits have resulted in Pass (Optimal level) and 6% of the audits have resulted in Pass (Action Level). All Pass (Action level) results have been resolved with a repeat OSLD audit, or an on-site ion chamber measurement. [ABSTRACT FROM AUTHOR]

Electron beam welding is a well known process used where high precision, high reliability welds are needed, often in exotic materials. Recently, it has been proposed to apply the electron beam produced in a standard scanning electron microscope (SEM), with reversible modifications to increase beam current, for microscale welding. In addition to providing the clean environment associated with the column vacuum, the SEM in imaging mode provides exceptional capabilities in visualising extremely small parts. Furthermore, the standard stage and beam motion controls offer the possibility of flexible programming of beam path with relatively minor software additions. In order to better evaluate the requirements for and effects of μE-beam welding (μEBW) on typical microtechnologically important materials, a clear understanding of the characteristics of the SEM's beam and its interaction with possible target materials is needed. The penetration ability of electrons depends strongly upon their accelerating voltage and the target they are being directed at. Hence, in some circumstances the beam may interact as a surface heat source, while in others it may act as a volume heat source, with important consequences on weld schedule development for the parts and geometry being welded. In this work, the authors explore some of the factors involved and propose simple models for the electron beam heat source which depend on the parameters being used. [ABSTRACT FROM AUTHOR]

Device-tissue interface geometry influences both the intensity of detected fluorescence and the extent of tissue sampled. Previous modelling studies have often investigated fluorescent light propagation using generalised tissue and illumination-collection geometries. However, the implementation of approaches that incorporate a greater degree of realism may provide more accurate estimates of light propagation. In this study, Monte Carlo modelling was performed to predict how illumination-collection parameters affect signal detection in multilayer tissue. Using the geometry and optical properties of normal and atherosclerotic aortas, results for realistic probe designs and a semi-infinite source-detection scheme were generated and compared. As illumination-collection parameters, including single-fibre probe diameter and fibre separation distance in multifibre probes, were varied, the signal origin deviated significantly from that predicted using the semi-infinite geometry, The semi-infinite case under-predicted the fraction of fluorescence originating from the superficial layer by up to 23% for a 0.2mm diameter single-fibre probe and over-predicted by 10% for a multifibre probe. These results demonstrate the importance of specifying realistic illumination-collection parameters in theoretical studies and indicate that targeting of specific tissue regions may be achievable through customisation of the illumination-collection interface. The device- and tissue-specific approach presented has the potential to facilitate the optimisation of minimally invasive optical systems for a wide variety of applications. [ABSTRACT FROM AUTHOR]

In recent decades, considerable research has been carried out both in measuring and modelling the brightness of the sky. Modelling is highly complex, as the properties of light emission (spatial and spectral distribution) are generally unknown, and the physical state of the atmosphere cannot be determined independently. The existing radiation transfer models lack the focus on light pollution and model only a narrow spectral range or do not consider realistic atmospheric circumstances. In this paper, we introduce a new Monte Carlo simulation for modelling light pollution, including the optical density of the atmosphere and multiple photon scattering, then we attempt to combine the available information of satellite and ground-based measurements to check the extent to which it is possible to verify our model. It is demonstrated that we need all the separate pieces of information to interpret the observations adequately. [ABSTRACT FROM AUTHOR]

The absolute efficiency of X-ray production has been determined for the K-lines of Al, Si and Cu; for the L-lines of Fe, Co, Cu, Ge and As; and for the M-lines of Hf, Ir, Pt, Au and Bi, using overvoltage ratios in the range 1–10. These emissions, with the exception of the Cu K, have critical excitation energies below 2.6 keV and are therefore typical of the lines used for X-ray microanalysis at low beam energies. For K-lines it is found that the experimental results are in good agreement with a Bethe, or a Casnati, cross-section model. For the L- and M-lines a Monte Carlo technique has been used to find an effective X-ray generation cross-section for each of the elements. The functional forms of these cross-sections are found to be in general agreement with proposed theoretical models. [ABSTRACT FROM AUTHOR]

Rapid, on-line measurement of feedstock mineralogy is a highly attractive technology for the mineral processing industry. A Monte Carlo particle transport-based modelling technique has been developed to help design and predict the measurement performance of on-line energy-dispersive X-ray diffraction (EDXRD) analysers. The accuracy of the technique was evaluated by performing quantitative phase analysis on a suite of fifteen synthetic potash ore samples. The diffraction profile of each sample was measured with a laboratory EDXRD analyser and an equivalent profile was simulated in the Monte Carlo package. Linear regression analysis was used to determine the mineral abundances in each sample from both the measured and modelled profiles. Comparison of the results showed that the diffraction profiles and measurement accuracies obtained by simulation agree very well with the measured data. [ABSTRACT FROM AUTHOR]