Modeling and development of an ANN-based smart pressure sensor in a dynamic environment

In many engineering applications, a capacitive pressure sensor (CPS) is placed in a dynamic environment in which the temperature variation is quite large. Since the response characteristics of a CPS are highly nonlinear and temperature dependent, in such situations, complex signal processing techniques are needed to obtain correct readout of the applied pressure. We have proposed an artificial neural network (ANN)-based smart capacitive pressure sensor, whose response characteristics can be estimated within an accuracy of ±1% error over a wide variation of temperature starting from −50°C to 150°C. This modeling scheme automatically takes care of all the nonidealities, such as, nonlinearity, offset, gain and temperature dependence, of the sensor. A novel idea of automatic collection of temperature information and its feeding into the ANN model is also proposed. In the practical implementation of this scheme, the hardware complexity poses a serious impairment. Since the tanh() functions are needed for implementation in the ANN-based model, to reduce the hardware requirement, we provide a simple scheme for computation of tanh(). Sensitivity analysis of the model with respect to the finite word-length constraint on the final stored weight values, and number of terms used in the implementation of tanh() function, have been carried out. A microcontroller-based implementation scheme for the ANN-based model is also suggested.     

‘Green’ synthesis and optical properties of silver–chitosan complexes and nanocomposites

Silver nanoparticles were synthesized in a chitosan biopolymer by an in situ ‘green’ chemical procedure, using d-glucose as the reducing agent. The reaction intermediates (silver–chitosan complexes) as well as the obtained nanocomposites were investigated using transmission electron microscopy, UV–vis, FTIR and photoluminescence spectroscopy. The theoretical analysis of the UV–vis absorption of the Ag–chitosan complexes suggested that the significant contribution to the complex spectrum arises from clusters of silver containing 4–9 atoms. The absorption spectrum of the nanocomposite exhibited a strong surface plasmon resonance band at 406 nm. The photoluminescence behavior of the pure chitosan, the silver–chitosan complexes and the nanocomposites were discussed in terms of morphology and silver weight content.     

Data Reduction of Body Surface Potential Maps by Means of Orthogonal Expansions

The electrical activity of the heart is reflected at the body surface by a potential distnbution which continuously changes in time throughout the cardiac cycle. Sampled versions of the potential data can be considered either as vectors or as matrices. From this conception, two different methods for data reduction can be developed within the frame of the Karhunen-Loeve expansion: a one-step method which implies an expansion into one set of eigenvectors, and a two-step method implying an expansion into two sets of eigenvectors. The set of eigen-vectors for the one-step method and the two sets of eigenvectors (space and time) for the two-step method were derived from the recorded body surface potentials of 136 subjects, used for the representation of the data of this group of subjects (design set), and also applied to a group of 135 subjects (test set). The rms error of the representation using 36 eigenvectors following the one-step method was 47 AV for the design set and 73 AV for the test set. When the two-step method was applied using six eigenvectors in space and six eigenvectors in time (also having 36 coefficients), the error was found to-be 77 , uV for the design set and 80 , uV for the test set. It is concluded that the one-step method is to be preferred for the representation of body surface potential data within a given group.     

Graphite melting under laser pulse heating

For a long time, the solid/liquid/vapor triple point of graphite has been a subject of debate, and despite the progress in the experimental techniques adopted, the uncertainties became even greater in recent years. In the experiments described in this paper spherical graphite specimens were heated by four tetrahedrally oriented laser beams to produce a fairly uniform temperature on the surface. A sufficiently large amount of molten graphite was produced to make it possible to identify the liquid/solid transition by a conventional thermoanalytical method. The temperature was measured by multichannel pyrometry, which enabled a detailed analysis of the perturbations and errors to be carried out. The triple point of graphite was determined to be T _t=4100±50 K and p _t=110±10 bar.Paper presented at the Second Workshop on Subsecond Thermophysics, September 20–21, 1990, Torino, Italy.     

ACR II: improved absolute cryogenic radiometer for low background infrared calibrations

A second-generation absolute cryogenic radiometer (ACR II) was developed for use at the Low Background Infrared calibration facility at the National Institute of Standards and Technology. The need for spectral calibrations of very sensitive [D* = 10(14) cm (Hz)1/2W(-1)] infrared detectors necessitated the use of a cryogenic infrared monochromator and a more sensitive radiometer. The improved low-power performance of the ACR II compared with the older absolute cryogenic radiometer (ACR) has also made it useful as the primary standard for the calibration of cryogenic blackbody sources that are used as low-power infrared sources. The responsivity of the new radiometer's receiver is 210 K/mW with a type A (random component) standard uncertainty of at most 7 pW when making power measurements of less than 10 nW. The original ACR has a responsivity of 29 K/mW and has a type A standard uncertainty of approximately 100 pW when making a similar low-noise-power measurement. Other properties of the radiometers are also described and compared.     

The procurement alignment framework construction and application

Procurement has become increasingly important for organizations acting in dynamic supply chains and competitive markets. In practice however, companies struggle with adapting and improving their procurement business function. In line with the general trend in management and organization studies, both scholars and practitioners aim to define an integrated procurement policy that is truly aligned on all organizational and IT aspects. The central aim of this paper is to present a framework that supports the definition and application of such an integrative procurement approach. The framework is developed upon insights from IT business alignment (more specifically IT Procurement alignment), procurement maturity measurement and segmentation. It facilitates organizations in monitoring the maturity and alignment of their procurement on five different business/IT perspectives. In addition, the framework enables specific procurement improvements by taking the situational aspect of procurement segmentation into account. The framework was validated twice: through interview expert consulting and through a questionnaire using scale analysis. In a case study it was found suitable for assessing procurement maturity and identifying concrete procurement improvements.     

The effect of expanded graphite on the physical properties of conductive EVA/wax phase change blends for thermal energy storage

A study of the morphology, dynamic mechanical, impact, and tensile properties of ethylene vinyl acetate copolymer (EVA)/expanded graphite (EG) and EVA/wax/EG composites is presented. The composites were prepared by melt blending. The EVA/EG composites showed ductile behavior, while brittle behavior was observed in the presence of wax. A finer dispersion of EG was observed in the matrix when wax was present. The storage modulus of the EVA/wax/EG composite was higher than that of the EVA/EG composite, which is ascribed to a better interaction between the EVA and the wax‐covered EG that significantly reduced the EVA chain mobility. The composites showed a decrease in impact strength with increasing EG and wax contents. There was a significant difference in the elongation at break between the EVA/EG and EVA/wax/EG composites, and little change in Young's modulus of EVA in the presence of EG and with increasing EG content. However, Young's modulus of the EVA/wax blends increased in the presence of and with increasing EG content. In all the investigated samples containing EVA and wax, irrespective of the EG content, the stress at break decreased with an increase in wax content. POLYM. COMPOS., 37:3025–3032, 2016. © 2015 Society of Plastics Engineers     

Theoretical claims necessitate basic research: Reply to Gawronski, Lebel, Peters, and Banse (2009) and Nosek and Greenwald (2009).

The authors of this reply article note that B. Gawronski, E. P. LeBel, K. R. Peters, and R. Banse (see record 2009-05290-002) (a) expressed agreement in their comment with the analysis put forward in the target article (J. De Houwer, S. Teige-Mocigemba, A. Spruyt, & A. Moors) (see record 2009-05290-001) and (b) pointed to a further implication for the way in which the implicitness of a measure should be examined. The current authors note that B. A. Nosek and A. G. Greenwald (see record 2009-05290-003), on the other hand, raised questions in their comment about the definition of the concept “implicit” in the target article, arguing for a fundamentally different approach to measurement that emphasizes not theoretical understanding but usefulness for predicting behavior. In this reply, the current authors respond to these comments and argue that when theoretical claims are made about measures, these claims should be backed up with appropriate evidence. In the absence of basic research, measures and their relation to behavior can only be described. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intercomparison of the LBIR Absolute Cryogenic Radiometers to the NIST Optical Power Measurement Standard

The Low Background Infrared calibration (LBIR) facility at the National Institute of Standards and Technology (NIST) presently maintains four absolute cryogenic radiometers (ACRs) which serve as standard reference detectors for infrared calibrations performed by the facility. The primary standard for optical power measurements at NIST-Gaithersburg has been the High Accuracy Cryogenic Radiometer (HACR). Recently, an improved radiometer, the Primary Optical Watt Radiometer (POWR), has replaced the HACR as the primary standard. In this paper, we present the results of comparisons between the radiometric powers measured by the four ACRs presently maintained by the LBIR facility to that measured by the HACR and POWR. This was done by using a Si photodiode light-trapping detector as a secondary transfer standard to compare the primary national standards to the ACRs maintained by the LBIR facility. The technique used to compare an ACR to the trap detector is described in detail. The absolute optical power measurements are found to be within 0.1 % of the primary standard for all the ACRs examined in this study.