Si(Li)NaI(Tl) sandwich detector array for measurements of trace radionuclides in soil samples

An ultra-sensitive X/γ-ray detector system for assaying trace radioactivity in actinide contaminated soil and ash samples has been developed. The new system consists of an array of 6 large Si(Li) X-ray detectors sensitive on both faces and mounted on edge in a paddle-shaped cryostat with a 14 cm diameter Be window on each side. The paddle, with a sample of the soil placed at each window, is sandwiched between 2 large NaI(Tl) scintillators which suppress the γ background. With X-rays being measured simultaneously from soil in 2 sample holders and background reduced by 50% using anticoincidence, the sensitivity of this detector is 4 times higher than that of conventionally mounted Si(Li) detectors. A soil sample containing 50 pCi/g ²³⁹Pu was measured in 5 min with an uncertainty of < 20% and a sample containing 7 pCi/g was measured in 1 h. With fwhm resolution of 400 eV at 17 keV, the ULβ₁ and NpL_β1 X-ray peaks are resolved thus permitting measurement of trace Pu in the presence of ²⁴¹Am. This is the most sensitive and selective detector known for nondestructive assay of radioactivity in soil and other samples.     

Technology invention and adoption in residential energy consumption: A stochastic frontier approach

In this paper we analyse the electricity consumption of a set of four traditional ‘white goods’ in a panel of ten EU countries observed over the period 1995–2013 with the aim of disentangling the amount of technical efficiency from overall energy saving using a stochastic frontier approach. The efficiency trend is modelled as a function of energy efficiency policies and innovation dynamics that combines invention and adoption processes using specific patents weighted by granular production data and worldwide bilateral import flows. Our model also accounts for potential endogeneity arising when innovation processes and economic growth are considered. With this replicable approach, the stochastic frontier framework allows for explicit modelling of innovation processes. Our results show that the efficiency component is related to changes in the energy efficient technological content of appliances. The ‘international’ component represents a predominant share of technological advancement and exerts a significant influence on the transient efficiency. Our evidence calls for an active role to be played by policy makers in focusing on innovation and trade policies in order to achieve more ambitious energy efficiency targets.     

Effect of elements with positive enthalpy of mixing on mechanical properties of bulk metallic glasses

Samples of (Cu₄₆Zr₄₆Al₈)_100?xZ_x metallic glass forming alloys with diameters 2–6 mm were prepared by injection casting. The effect of minor amounts of elements Z = Gd, Co and Re with positive enthalpy of mixing within the Gd–Zr, Cu–Co and Cu–Re terminal systems was compared. The addition of Gd up to x = 2 slightly enhances the glass forming ability, Co reduces the critical diameter of bulk metallic glass formation, whereas even for small fractions of Re bulk samples were crystalline, but only amorphous splats can be prepared. Both Gd and Co diminish the crystallization temperature T_x with respect to the Cu₄₆Zr₄₆Al₈ master alloy, but in Re-bearing splats T_x is increased. Alloying with optimum amounts of Gd and Co up to x = 2 leads to plastic deformability of rods, 2 and 3 mm in diameter, in comparison with the brittle Cu₄₆Zr₄₆Al₈ bulk metallic glass.     

Review and analysis of solutions of the three point perspective pose estimation problem

In this paper, the major direct solutions to the three point perspective pose estimation problems are reviewed from a unified perspective beginning with the first solution which was published in 1841 by a German mathematician, continuing through the solutions published in the German and then American photogrammetry literature, and most recently in the current computer vision literature. The numerical stability of these three point perspective solutions are also discussed. We show that even in case where the solution is not near the geometric unstable region, considerable care must be exercised in the calculation. Depending on the order of the substitutions utilized, the relative error can change over a thousand to one. This difference is due entirely to the way the calculations are performed and not due to any geometric structural instability of any problem instance. We present an analysis method which produces a numerically stable calculation.