A broadband power meter calibration system in the frequency rangefrom 10 MHz to 40 GHz using a coaxial calorimeter

A broadband power meter calibration system based on a newly constructed coaxial calorimeter has been developed in the frequency region 10 MHz-40 GHz. The RF power is measured as the difference of DC power supplied to the calorimeter built-in heater in the RF load, when RF is turned off and on, holding an isothermal control between the RF load and a temperature reference. To minimize the error due to the adiabatic coaxial waveguide, we devised a new method utilizing its output port as a test port. The evaluations showed a calibration uncertainty of (0.28-2.2)% expressed by one standard deviation at the 1 mW level in the full band     

An area-average approach to peening residual stress under multi-impacts using a three-dimensional symmetry-cell finite element model with plastic shots

We estimate realistic peening residual stress based on area-averaged solution using a 3D multi-impact symmetry-cell finite element (FE) model. The analytical model includes elaborate factors reflecting actual peening phenomena and plastic shot effect. Area-averaged solution is much closer to X-ray diffraction (XRD) experimental solution than four-node-averaged solution in plastic shot FE model. The area-averaged solution, moreover, converges to the perfect equi-biaxial stress state. From this, based on the area-averaged solution, we obtained the FE Almen curve, and then derived related equations among FE arc height, FE coverage and shot velocity. The FE Almen curve corresponds well with experimentally obtained by Kim et al. [Kim T, Lee JH, Lee H. An Effective 2D FE model with plastic shot for evaluation of peening residual stress. J Mater Process Technol, submitted for publication; Kim T, Lee H, Lee JH. A 3D phenomenological FE model for unique solution of peening stress due to multi-impacts. Int J Numer Methods Eng, submitted for publication]. Using the FE Almen curve, we examine the FE area-averaged solution in major peening materials. The FE solutions of surface, maximum compressive residual stress and deformation depth quite reach experimental solutions. The FE Almen curve is thus confirmed to be useful for estimation of residual stress solution. Consequently, we validated that the concept of area-averaged solution is the systematical analytical method for evaluation of real peening residual stress.     

Elastoplastic stress analysis of a short fibre reinforced composite using a three-dimensional finite element model with several close to reality features

The knowledge of stress distributions within a short fibre reinforced composite is useful for an understanding of the micromechanical load transfer between fibre and matrix. This is especially interesting in the case of a plastifying matrix about which little can be found in the literature. This paper first describes a newly developed finite element model in three dimensions which contains several closer to reality aspects than conventional models. Using this model, stress distributions are presented for an almost perfectly elastic and for a strongly plastified deformation stage of a specimen with a high degree of fibre orientation. These distributions and their implications are discussed in detail.     

Creep mapping in a polycrystalline ceramic: application to magnesium oxide and magnesiowustite

The construction of deformation mechanism maps for a polycrystalline ionic solid in which anion and cation transport are coupled has been demonstrated. Because of anioncation ambipolar coupling, two regimes of Coble creep are possible in systems where anion grain boundary transport is rapid: (1) rate-controlled at low temperatures and small grain sizes by cation grain-boundary diffusion, and (2) rate-limited at high temperatures and large grain sizes by anion grain-boundary diffusion. A new type of deformation mechanism map was introduced in which the temperature and grain size were primary variables. This map was shown to be particularly useful for materials which deform primarily by diffusional creep mechanisms. Ambipolar diffusional creep theory was used to construct several deformation mechanism maps for polycrystalline MgO and magnesiowustite over wide ranges of stress, grain size, temperature and composition.     

Rapid measurement of methyl cellulose precipitable tannins using ultraviolet spectroscopy with chemometrics: application to red wine and inter-laboratory calibration transfer

Information relating to tannin concentration in grapes and wine is not currently available simply and rapidly enough to inform decision-making by grape growers, winemakers, and wine researchers. Spectroscopy and chemometrics have been implemented for the analysis of critical grape and wine parameters and offer a possible solution for rapid tannin analysis. We report here the development and validation of an ultraviolet (UV) spectral calibration for the prediction of tannin concentration in red wines. Such spectral calibrations reduce the time and resource requirements involved in measuring tannins. A diverse calibration set (n = 204) was prepared with samples of Australian wines of five varieties (Cabernet Sauvignon, Shiraz, Merlot, Pinot Noir, and Durif), from regions spanning the wine grape growing areas of Australia, with varying climate and soils, and with vintages ranging from 1991 to 2007. The relationship between tannin measured by the methyl cellulose precipitation (MCP) reference method at 280 nm and tannin predicted with a multiple linear regression (MLR) calibration, using ultraviolet (UV) absorbance at 250, 270, 280, 290, and 315 nm, was strong (r(2)val = 0.92; SECV = 0.20 g/L). An independent validation set (n = 85) was predicted using the MLR algorithm developed with the calibration set and gave confidence in the ability to predict new samples, independent of the samples used to prepare the calibration (r(2)val = 0.94; SEP = 0.18 g/L). The MLR algorithm could also predict tannin in fermenting wines (r(2)val = 0.76; SEP = 0.18 g/L), but worked best from the second day of ferment on. This study also explored instrument-to-instrument transfer of a spectral calibration for MCP tannin. After slope and bias adjustments of the calibration, efficient calibration transfer to other laboratories was clearly demonstrated, with all instruments in the study effectively giving identical results on a transfer set.     

Noninvasive near-infrared blood glucose monitoring using a calibration model built by a numerical simulation method: Trial application to patients in an intensive care unit

We have applied a new methodology for noninvasive continuous blood glucose monitoring, proposed in our previous paper, to patients in ICU (intensive care unit), where strict controls of blood glucose levels are required. The new methodology can build calibration models essentially from numerical simulation, while the conventional methodology requires pre-experiments such as sugar tolerance tests, which are impossible to perform on ICU patients in most cases. The in vivo experiments in this study consisted of two stages, the first stage conducted on healthy subjects as preliminary experiments, and the second stage on ICU patients. The prediction performance of the first stage was obtained as a correlation coefficient (r) of 0.71 and standard error of prediction (SEP) of 28.7 mg/dL. Of the 323 total data, 71.5% were in the A zone, 28.5% were in the B zone, and none were in the C, D, and E zones for the Clarke error-grid analysis. The prediction performance of the second stage was obtained as an r of 0.97 and SEP of 27.2 mg/dL. Of the 304 total data, 80.3% were in the A zone, 19.7% were in the B zone, and none were in the C, D, and E zones. These prediction results suggest that the new methodology has the potential to realize a noninvasive blood glucose monitoring system using near-infrared spectroscopy (NIRS) in ICUs. Although the total performance of the present monitoring system has not yet reached a satisfactory level as a stand-alone system, it can be developed as a complementary system to the conventional one used in ICUs for routine blood glucose management, which checks the blood glucose levels of patients every few hours.     

Dynamic hardness measurements using a dropped ball: with application to 1018 steel

A practical method for measuring the hardness of metals at high strain rates (>10³ s⁻¹), using a dropped ball, is developed and demonstrated on cold-rolled plain carbon (1018) steel. The metal is assumed to be one-dimensional and rigid plastic. By formulating the problem in terms of the lateral, rather than the depth, dimensions of the indentation, the dynamic hardness can be obtained at load, obviating the need for rebound energy corrections. In addition, the Tabor strain equation relating to equivalent unidirectional compression is derived, and methods are also derived to include “piling-up” around indentations for plastic flow at constant volume. A previously unrecognized phenomenon that can occur in projectile indentation of metals, “ballistic strain softening”, is described. It is related to the fact that the dynamic hardness obtained by this test is a function of the ball radius times the strain rate divided by the strain. As a result, comparison of the dropped ball test flow stress data with those of constant strain rate tests requires a transform of the Tabor strain and strain rate data to constant strain rate conditions. When this is done, the dynamic yield stress data that are determined as a function of the effective strain rates agree with comparable published data for mild steel obtained using more conventional tests. The results also show that there is greatly enhanced strain hardening in irons and steels above a critical strain rate, which increases with purity. A dislocation model is used to explain this increase in terms of an additional dislocation generation mechanism coming into play.     

From laboratory- to pilot-scale: moisture monitoring in fluidized bed granulation by a novel microwave sensor using multivariate calibration approaches

Recently, microwave resonance technology (MRT) sensor systems operating at four resonances instead of a single resonance frequency were established as a process analytical technology (PAT) tool for moisture monitoring. The additional resonance frequencies extend the technologies’ possible application range in pharmaceutical production processes remarkably towards higher moisture contents. In the present study, a novel multi-resonance MRT sensor was installed in a bottom-tangential-spray fluidized bed granulator in order to provide a proof-of-concept of the recently introduced technology in industrial pilot-scale equipment. The mounting position within the granulator was optimized to allow faster measurements and thereby even tighter process control. As the amount of data provided by using novel MRT sensor systems has increased manifold by the additional resonance frequencies and the accelerated measurement rate, it permitted to investigate the benefit of more sophisticated evaluation methods instead of the simple linear regression which is used in established single-resonance systems. Therefore, models for moisture prediction based on multiple linear regression (MLR), principal component regression (PCR), and partial least squares regression (PLS) were built and assessed. Correlation was strong (all R²?>?0.988) and predictive abilities were rather acceptable (all RMSE ≤0.5%) for all models over the whole granulation process up to 16% residual moisture. While PCR provided best predictive abilities, MLR proofed as a simple and valuable alternative without the need of chemometric data evaluation.     

Monte Carlo simulations of electromagnetic wave scattering from a random rough surface with three-dimensional penetrable buried object: mine detection application using the steepest-descent fast multipole method.

We present a statistical study of the electric field scattered from a three-dimensional penetrable object buried under a two-dimensional random rough surface. Monte Carlo simulations using the steepest-descent fast multipole method (SDFMM) are conducted to calculate the average and the standard deviation of the near-zone scattered fields. The SDFMM, originally developed at the University of Illinois at Urbana-Champaign, has been modified to calculate the unknown surface currents both on the rough ground and on the buried object that are due to excitation by a tapered Gaussian beam. The rough ground medium used is an experimentally measured typical dry Bosnian soil with 3.8% moisture, while the buried object represents a plastic land mine modeled as an oblate spheroid with dimensions and burial depth smaller than the free-space wavelength. Both vertical and horizontal polarizations for the incident waves are studied. The numerical results show that the TNT mine signature is almost 5% of the total field scattered from the ground. Moreover, relatively recognizable object signatures are observed even when the object is buried under the tail of the incident beam. Interestingly, even for the small surface roughness parameters considered, the standard deviation of the object signature is almost 30% of the signal itself, indicating significant clutter distortion that is due to the roughness of the ground.     

Stress intensity factors for through-thickness cracks in a wide plate: Derivation and application to arbitrary weld residual stress fields

Exact closed-form stress intensity factor (SIF) solutions have been developed for mode-I, II and III through-thickness cracks in an infinite plate. Centre-crack problems have been analysed comprehensively in the literature, but the focus has been on the effect of simple loading about the crack centre. In the current work, the formula of Sih-Paris-Erdogan was extended to consider the difference in SIF on the left and right crack tips under an asymmetric stress field. Mathematical manipulations were performed to derive exact stress magnification factors for SIF computations and simultaneously circumvent the problem of crack-tip stress singularity. The solutions so obtained are applied to derive the residual SIFs that would act on a crack growing under the influence of the residual stress fields associated with VPPA (variable polarity plasma arc) and friction stir welds, using measured residual stress profiles.     

Identification of animal glue species in artworks using proteomics: application to a 18th century gilt sample

This study proposes a proteomic-based strategy for the identification of the origin species of glues used as binding media and adhesives in artworks. The methodology, based on FTICR high resolution mass spectrometry, was evaluated on glues from different animal origin (i.e., bovine, rabbit, and fish). The analysis of the peptide mixture resulting from the enzymatic hydrolysis of the proteins led to the identification of species-specific peptides. Up to 15 specific peptides were identified for the bovine species and three for the rabbit species and, in the case of sturgeon glue, three fish-specific peptides were found by sequence homology to the rainbow trout. Then, the method was applied to authenticate different rabbit skin glue samples, including a 100 year-old sample named "Colle à Doreurs" coming from the "Maison Totin-Frères". For this sample, two specific peptides of rabbit collagen were identified. To evaluate the method in a complex matrix, model paints composed of lead white, linseed oil, and animal glue were prepared. Species-specific peptides were identified in each paint sample. Finally, a gilt sample from St Maximin church dating from the eighteenth century was analyzed, and 13 peptides specific to bovine collagens were identified starting from very low sample amount (50 μg).     

Vaccinating in disease-free regions: a vaccine model with application to yellow fever.

Concerns regarding natural or induced emergence of infectious diseases have raised a debate on the pros and cons of pre-emptive vaccination of populations under uncertain risk. In the absence of immediate risk, ethical issues arise because even smaller risks associated with the vaccine are greater than the immediate disease risk (which is zero). The model proposed here seeks to formalize the vaccination decision process looking from the perspective of the susceptible individual, and results are shown in the context of the emergence of urban yellow fever in Brazil. The model decomposes the individual's choice about vaccinating or not into uncertain components. The choice is modelled as a function of (i) the risk of a vaccine adverse event, (ii) the risk of an outbreak and (iii) the probability of receiving the vaccine or escaping serious disease given an outbreak. Additionally, we explore how this decision varies as a function of mass vaccination strategies of varying efficiency. If disease is considered possible but unlikely (risk of outbreak less than 0.1), delay vaccination is a good strategy if a reasonably efficient campaign is expected. The advantage of waiting increases as the rate of transmission is reduced (low R0) suggesting that vector control programmes and emergency vaccination preparedness work together to favour this strategy. The opposing strategy, vaccinating pre-emptively, is favoured if the probability of yellow fever urbanization is high or if expected R0 is high and emergency action is expected to be slow. In summary, our model highlights the nonlinear dependence of an individual's best strategy on the preparedness of a response to a yellow fever outbreak or other emergent infectious disease.     

Advancing NMR sensitivity for LC-NMR-MS using a cryoflow probe: application to the analysis of acetaminophen metabolites in urine

Cryogenic cooling of the NMR radio frequency coils and electronics to give greatly enhanced sensitivity is arguably the most significant recent advance in NMR spectroscopy. Here we report the first cryogenic probe built in flow configuration and demonstrate the application to LC-NMR-MS studies. This probe provides superior sensitivity over conventional noncryogenic flow NMR probes, allowing the use of 100 microL of untreated urine (40% less material than previous studies that required preconcentration) and yet revealing drug metabolites hitherto undetected by LC-NMR-MS at 500 MHz. Besides the known sulfate and glucuronide metabolites, previously undetected metabolites of acetaminophen were directly observable in a 15-min on-flow experiment. Simultaneous MS data also provided knowledge on the NMR-silent functional moieties. Further, stop-flow LC-NMR-MS experiments were conducted for greater signal-to-noise ratios on minor metabolites. The cryoflow probe enables the NMR analysis of lower concentrations of metabolites than was previously possible for untreated biofluids. This strategy is generally applicable for samples containing mass-limited analytes, such as those from drug metabolism studies, biomarker and toxicity profiling, impurity analysis, and natural product analysis.     

Expansion of a cavity in a rubber block under stress: application of the asymptotic expansion method to the analysis of the stability and bifurcation conditions

In order to analyse the stability and bifurcation phenomena occurring during expansion of a small void in a rubbery material, the behaviour of spherical shells submitted to a combined far-field pressure and uniaxial tension has been investigated, considering a general nonlinear isotropic elastic compressible behaviour of the material and without any restrictions on the shell thickness. A radial solution for the deformation gradient with a spherical symmetry has been exhibited, which is valid for any behaviour law and consists of a homogeneous deformation. The three-dimensional problem is then linearized around this trivial solution, and we show the existence of a pressure interval containing the zero value, in which the solution is reduced to the trivial solution, which is therefore infinitesimally stable. The condition for stability obtained is compared with Hadamard's condition; particularly, it is shown that both are identical when the material is supposed to have a St Venant-Kirchhoff behaviour law. When the applied pressure lies outside the stability interval, we determine the bifurcation points of the shell around the trivial solution, first when only a pressure is applied and secondly when there is an additional far-field tension, much smaller than the applied pressure. The form of the stress distribution on the boundary of the cavity suggests a possible bifurcation of the spherical solution towards a family of axisymmetric solutions. Within this hypothesis, we get a relation between the geometrical parameter of the shell (its radius and thickness), the mechanical properties of the material and the critical load. The analyses provide evidence of the non-uniqueness of the bifurcation behaviour, since we exhibit some peculiar bifurcation points associated with an infinity of branches of axisymmetric solutions.     

How to search the experimental conditions that improve a Partial Least Squares calibration model: Application to a flow system with electrochemical detection for the determination of sulfonamides in milk

This paper deals with the selection of experimental conditions and how the signals obtained in these conditions influence the fitted Partial Least Squares calibration model. The multivariate signals come from a flow analysis system with amperometric detection when determining sulfadiazine, sulfamerazine and sulfamethazine in milk.The solution (carrier plus analyte) was pumped through the system to provide a continuous supply of analyte to the cell. The detector was programmed for a scan mode operation being the multivariate signal the hydrodynamic voltammogram. To obtain an analytical signal of enough analytical quality, the Net Analyte Signal and its standard deviation have been optimised by using an experimental design. The conflicting behaviour of the two responses has been solved by estimating the Pareto-optimal front.The multivariate signals recorded in the optimal conditions found have been calibrated by Partial Least Squares regression and their figures of merit validated according to the criteria established in European Decision 2002/657/EC.In relation to the permitted limit, 100 µg l^− 1 in milk, for the total content of sulfonamides established in the Commission Regulation EC no. 281/96 the proposed method has a decision limit of 109.1 µg l^− 1 and the capability of detection is 117.9 µg l^− 1 for both probability of false non-compliance and of false compliance equal to 5%. A recovery of 86.5% ± 2.4% (n = 5) has been obtained.     

Migration NSGA: method to improve a non-elitist searching of Pareto front,with application in magnetics

The paper describes a migration strategy to improve classical non-dominated sorting genetic algorithm (NSGA) to find optimal solution of a multi-objective problem. Migration NSGA has been tested to assess its performance using analytical functions for which the Pareto front is known in analytical form, as well as two case studies in electromagnetics, for which the Pareto front is not known a priori. This strategy improves the approximation of the Pareto-optimal solutions of a multi-objective problem by introducing new individuals in the population miming the effect of migrations.     

Entropy propagation analysis in stochastic structural dynamics: application to a beam with uncertain cross sectional area

This paper investigates the impact of different probabilistic models of uncertain parameters on the response of a dynamical structure. The probabilistic models of the uncertain parameters are constructed using the maximum entropy principle, where different information is considered, such as bounds, mean value, etc. Nested probabilistic models are constructed with increasing information; as the information given increases, the level of entropy of the input model decreases. The response of the linear dynamical model is given in the frequency domain, and the propagation of the input uncertainty throughout the computational model is analyzed in terms of Shannon’s entropy. Low and high frequencies are analyzed because uncertainties propagate differently depending on the frequency band. A beam discretized by means of the finite element method with random cross sectional area (random field) is the application analyzed.     

Relating retinal nerve fiber thickness to behavioral sensitivity in patients with glaucoma: application of a linear model

Glaucoma causes damage to the retinal ganglion cells and their axons, and this damage can be detected with both structural and functional tests. The purpose of this study was to better understand the relationship between a structural measure of retinal nerve fiber layer (RNFL) and the most common functional test, behavioral sensitivity with static automated perimetry (SAP). First, a linear model, previously shown to describe the relationship between local visual evoked potentials and SAP sensitivity, was modified to predict the change in RNFL as measured by optical coherence tomography. Second, previous work by others was shown to be consistent with this model.