Results of the ASTM field test of tristimulus weighting functions

In 1993, the American Society for Testing and Materials carried out a field test of newly calculated tristimulus weighting factors. These weighting factors had been calculated by a method proposed by Venable. the test also included a method of correction for bandpass dependence put forth by Stearns. the purpose of the trial was to assess the possible reduction in bandpass dependence introduced by each of these sets of weights. A large number of sets of spectral data were gathered from the cooperators in the field test. Results of integration by the various sets of tristimulus weighting factors were calculated. A total of 15 120 color differences were calculated and statistics were derived to test the probable error resulting from each method of correction. Errors attributable to bandpass dependence were on the order of a few tenths to as much as one CIELAB unit when uncorrected weight sets were used. These errors could be reduced to a few hundreths of a CIELAB unit, and in some cases to a few thousandths of a unit, by employing one correcting strategy or the other. an overall mix of strategies was ultimately chosen to minimize the bandpass dependence over the entire range of weight sets. Utilizing this mixed strategy, the median error introduced into 10-nm integration by bandpass dependence was only 0.004 CIELAB units. © 1995 John Wiley & Sons, Inc.     

Early detection of ageing in solder joints through laser probe thermal analysis of the peltier effect

We have recently developed an optical contactless method for testing the quality of solder joints during accelerated thermal cycling ageing processes.¹ The method was based upon the measurement of the dynamic thermal behaviour of the joint to short bursts of Joule heating. It has proved to be efficient in revealing the formation of cracks at the lead-solder interface. We present a method to evaluate ageing at a much earlier stage in the cycling process. We have observed in earlier work,¹ that before cracks appear, structural changes occur in the solder at the lead-solder interface. The thermal response of the solder joint is recorded over time to a Peltier heat perturbation produced by flowing a current pulse through the interface where structural changes occur. The key point in this method is to discriminate the Peltier effect from the Joule thermal response because both effects generate heat. The variation of the early Peltier response in the thermal cycling ageing tests is seen as a quantitative signature of the structural changes in the lead-solder interface.     

Novel miniature integrated optical goniometers

A new principle and arrangement for directly determining the angle of incidence of an optical beam on an object are proposed and demonstrated. The novelty of the approach lies in the realization of a ‘smart object’, which extracts a portion of the incident beam's power into an optical waveguide attached to the object's surface or embedded in its body for converting the angle of incidence into the position of a guided beam with finite lateral extent. This ‘integrated optical light pointer’ beam is accomplished by means of creating additional degrees of freedom on the target in two different ways. While a first type is based on introducing spatial variations of the waveguide thickness, a second type makes use of a chirp of the grating periodicity. The feasibility for practical applications has been experimentally demonstrated by a direct comparison with a commercial high-resolution encoder, resulting in an r.m.s. error of <30′'. Measurements have been performed for chips fabricated based on replicated polycarbonate substrates and with no external optics, showing the great potential of this approach for realizing low-cost yet high-performance miniature goniometers.     

Some experimental findings in compression-after-impact (CAI) tests of CF/PEEK (APC-2) and conventional CF/epoxy flat plates

Compression-after-impact (CAI) tests have been conducted for quasi-isotropic thick plates with 48 plies by using the NASA method and on plates with 32 plies by using the SACMA method. Specimens are made of CF/PEEK (APC-2) and conventional CF/epoxy for the NASA plates and CF/epoxy for the SACMA plates. In the NASA CAI tests, the sequence of delamination buckling and its propagation is clearly revealed through various experimental techniques. One major technique is moiré topography, and the other is thermo-mechanical stress analysis with a high-accuracy infrared sensor. The arrest of delamination propagation just before catastrophic failure due to high fracture toughness is clearly captured by the moiré camera. This behavior provides good CAI values of CF/PEEK. The initial buckling properties of the delaminated region by the impact are then extensively discussed. Numerical predictions of initial buckling stress have been obtained by modelled geometry of the delaminated region simplified from its precise structure clarified by ultrasonic C-scanning. They agree fairly well with the experimental results. The in-plane stress distribution in the delaminated region before initial buckling is measured by an infrared stress graphic system. This compared favorably with finite element predictions. Two types of symmetric buckling modes with respect to the central plate surface, twin and single peak ones, are experimentally captured.     

Solving regularized least squares with qualitatively controlled adaptive cross‐approximated matrices

The adaptive cross‐approximation (ACA) technique is applied to accelerating an inverse‐problem solver that estimates charge distribution on a dielectric spacer. The ACA generates an approximated system‐matrix that enables us to carry out high‐speed inverse calculation. We designed an approximation procedure based on ACA with some additional concepts, that is, (a) partitioning of matrix based on algebraic information, (b) approximation quality control based on matrix norms, and so on. The tested solver (LSQR for regularized least squares) with ACA demonstrates about 10 times faster performance than that without ACA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 10–18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20326     

A comparative study of color measurement lntstrumentation

A multiplant Quality Improvement Team [QIT] was firmed to develop and implement an evaluation program for various color measurement .systems as potential replacements for the then-current aging systems. The emphasis qf this article is the analytical methodology utilized to evaluate the various color systems. The evaluation program consisted cf two phases. Phase I was a general overview/review of several systems, while Phase II was an extensive internal comparative evaluation measurement systems. These were Milton-Roy's ColorMate HDS, HunterLab's Ultrascan, Datacolor's CS-5, and BYK-Gardner's The Color Sphere [TCS]. The main comparison criteria were interinstrument agreement [agreement between two instruments ofthe same system], user-friendly software and computer interface capability, vendor amenability to a long-term logistical and maintenance relationship, and price. All systems were evaluated by duplicate measurements on various color tiles, yarns, and polymer flakes-over 1600 measurements on each system. The systems were compared with an instrument matrix, a decision matrix, and a product matrix. The instrument matrix was a comparison qfinstrument parameters, software/math treatments, and economics. The decision matrix was a forced ranking of each system by each criteria category [1–4 scale, with 1 representing the best and 4 representing the worst]. The product matrix accentuated the relative importance ofone criterion category over another by multiplying the forced ranking by the criticality of the category. The criticality of a given category wus determined by consensus within the QIT. Thr combination qf the three matrices allowed the evaluator[.s] t o select the color rneasuremmt system that best satixfied the color measurement needs and requirements of their facility and their products. For this evaluation, all ofthe evaluated systems were superior to the then-current agingsystems. As a result of this methodology, one instrument emerged as clearly superior. © 1994 John Wrley & Sons, Inc.     

离心泵性能参数的自动测定和自动控制

通过将计算机技术应用于离心泵性能参数的研究，实现了离心泵性能参数的自动测定和自动控制。     

Proposal of a uniform color scale for virgin olive oils

A new color scale was developed from a broad data set of 1700 virgin olive oil samples over four crop seasons, which can be considered highly representative of the whole color range of virgin olive oils available in Spain. This color scale provides a new set of 60 color standards, improving the results achieved by the old 60-color standards proposed by the bromthymol blue method. Seeking the greatest possibility of including a near match between colors of virgin olive oils and proposed standards, we developed our new color scale using a recent uniform color space, with standards placed in a regular rhombohedral lattice like the one employed by the Uniform Color Scales of the Optical Society of America. The average color difference between each of the 1700 virgin olive oils and its nearest standard is reduced from 8.17 CIELAB units, using the bromthymol blue standards, to 3.99 CIELAB units using the new standards. Within a color tolerance of 7.0 CIELAB units, 93.2% of our virgin olive oils can be classified with the new standards, but only 59.1% with the bromthymol blue ones. In the interest of future adoption, the performance of the new color standards should be tested by industry and researchers.     

Perceptual image preview

Image preview is a convenient way to browse large or multiple images on small displays. However, current signal-level image resampling algorithms may remove many features of interest in the preview image. In this paper, we propose perceptual image preview which retains more perceptual features such that users can inspect features of interest by viewing the preview image only and without zooming in. This technology has two components, structure enhancement and perceptual feature visualization. Structure enhancement enhances the image structure while suppressing subtle details using a gradient modulation method, thus making the succedent perceptual features more apparent. For perceptual feature visualization, features of interest detected in the picture is visualized on the structure enhanced preview image. We demonstrate with two examples of most commonly used image quality features, image blur and noise. The effectiveness of the proposed method is validated by experimental results.