Error analysis and planning accuracy for dimensional measurement in active vision inspection

This paper discusses the effect of spatial quantization errors and displacement errors on the precision dimensional measurements for an edge segment. Probabilistic analysis in terms of the resolution of the image is developed for 2D quantization errors. Expressions for the mean and variance of these errors are developed. The probability density function of the quantization error is derived. The position and orientation errors of the active head are assumed to be normally distributed. A probabilistic analysis in terms of these errors is developed for the displacement errors. Through integrating the spatial quantization errors and the displacement errors, we can compute the total error in the active vision inspection system. Based on the developed analysis, we investigate whether a given set of sensor setting parameters in an active system is suitable to obtain a desired accuracy for specific dimensional measurements, and one can determine sensor positions and view directions which meet the necessary tolerance and accuracy of inspection.published_or_final_versio

Tolerance analysis and synthesis by interval constraint networks

This paper proposes interval constraint network and interval propagation techniques for automatic tolerance design. A hierarchical representation is utilized in the interval constraint network. The consistency of a constraint is defined for the purpose of tolerance design. Forward and backward propagation techniques are introduced in the interval constraint network for tolerance analysis and synthesis, respectively. Both a propagation technique for a single constraint and a parallel propagation technique for multiple constraints between two adjacent levels in the network are introduced. Experiments conducted to illustrate the procedures of tolerance analysis and synthesis for the tank problem are described.published_or_final_versio

Differentiation of Human Embryonic Stem Cells into Cells with Corneal Keratocyte Phenotype

Corneal transparency depends on a unique extracellular matrix secreted by stromal keratocytes, mesenchymal cells of neural crest lineage. Derivation of keratocytes from human embryonic stem (hES) cells could elucidate the keratocyte developmental pathway and open a potential for cell-based therapy for corneal blindness. This study seeks to identify conditions inducing differentiation of pluripotent hES cells to the keratocyte lineage. Neural differentiation of hES cell line WA01(H1) was induced by co-culture with mouse PA6 fibroblasts. After 6 days of co-culture, hES cells expressing cell-surface NGFR protein (CD271, p75NTR) were isolated by immunoaffinity adsorption, and cultured as a monolayer for one week. Keratocyte phenotype was induced by substratum-independent pellet culture in serum-free medium containing ascorbate. Gene expression, examined by quantitative RT-PCR, found hES cells co-cultured with PA6 cells for 6 days to upregulate expression of neural crest genes including NGFR, SNAI1, NTRK3, SOX9, and MSX1. Isolated NGFR-expressing cells were free of PA6 feeder cells. After expansion as a monolayer, mRNAs typifying adult stromal stem cells were detected, including BMI1, KIT, NES, NOTCH1, and SIX2. When these cells were cultured as substratum-free pellets keratocyte markers AQP1, B3GNT7, PTDGS, and ALDH3A1 were upregulated. mRNA for keratocan (KERA), a cornea-specific proteoglycan, was upregulated more than 10,000 fold. Culture medium from pellets contained high molecular weight keratocan modified with keratan sulfate, a unique molecular component of corneal stroma. These results show hES cells can be induced to differentiate into keratocytes in vitro. Pluripotent stem cells, therefore, may provide a renewable source of material for development of treatment of corneal stromal opacities. © 2013 Chan et al

Is the quasi-steady state a real behaviour: a micromechanical perspective

Discussion (MM Rahman and SR Lo) and authors' reply (J Yang and BB Dai)Whether the so-called quasi-steady state is a real material response is a fundamental yet controversial question in the study of undrained shear behaviour of sand. An attempt is made here to clarify the question from a micromechanical viewpoint by means of a grain-scale modelling technique combined with statistical analyses. The study shows that the quasi-steady state is a real behaviour rather than a test-induced phenomenon; it is a transition state, and can be regarded as the result of spatial rearrangement of discrete particles sheared under the constant-volume condition. The quasi-steady state has distinct features that make it different from the steady state at both the macro scale and micro scale. During the loading process, the average number of contacts per particle decreases with strain until the quasi-steady state emerges, and after that it increases gradually to an approximately constant value at large deformations associated with the steady state. This result suggests that the loss of contacts is most pronounced at the quasi-steady state. The study also shows that the contact normal forces and particle rotations play a major role in the deformation process, whereas the contributions of contact tangential forces and particle sliding appear to be minor.published_or_final_versio

Camera settings for dimensional inspection using displacement and quantization errors

An important aspect of inspection planning involves determining camera poses based on some criterion. We seek to find camera poses where the effects of displacement and quantization errors are minimal. The mean squared error is formulated, including all dependencies, and minimized to determine an optimal camera pose that satisfies the sensor constraints of resolution, focus, field-of-view, and visibility. Dimensional tolerances for line entities are also formulated and exploited to determine the acceptability of a given camera pose for all entities observed.published_or_final_versio

Underwriting and investment risks in the property-liability insurance industry: Evidence prior to the 9-11 event

Underwriting and investment are two important and related business activities of insurance companies. However, studies on the interrelation between underwriting and investment risks of Property-Liability (P-L) insurance companies are sparse in the literature. Using a sample of US P-L insurers, this article conducts an empirical investigation of how these two risks are associated with each other in the 1994-2000 period (before the September 11th terrorist attack in 2001). Our results, robust to various estimations, suggest that there is no significant relationship between the underwriting and investment risks among our sample firms. Such results based on pre 9-11 event period provide some support for the conjecture of Achleitner et al. (Geneva Pap Risk Insur Issues Pract 27:275-282, 2002) that many insurance companies may have failed to take an integrated approach to risk management. This resulted in a heavy loss due to dual exposures in both underwriting and investment in the 9-11 event. In the aftermath of the recent global financial crisis, risk taking and risk management of financial institutions have received more attention and increasing scrutiny. We believe the current paper provides some useful insights in this vein. © 2010 Springer Science+Business Media, LLC.postprin

Rib waveguides for mid-infrared silicon photonics

Design rules for both single-mode and polarization-independent strained silicon-on-insulator rib waveguides at the wavelength of 3.39 mu m are presented for the first time to our knowledge. Waveguide geometries with different parameters, such as waveguide height, rib width, etch depth, top oxide cover thickness and sidewall angle, have been studied in order to investigate and define design rules that will make devices suitable for mid-IR applications. Chebyshev bivariate interpolation with a standard deviation of less than 1% has been used to represent the zero-birefringence surface. Experimental results for the upper cladding stress level have been used to determine the influence of top oxide cover thickness and different levels of upper cladding stress on waveguide characteristics. Finally, the polarization-insensitive and single-mode locus is presented for different waveguide heights. (C) 2009 Optical Society of Americ

An Investigation of Corporate Social Disclosures in U.K. & China Accountancy Firms

ABSTRACT This study provides an empirical analysis of practices and characteristics of accounting firms in both UK and China relating to corporate social disclosure in annual reports and on their official web sites. It found that country of domicile, company size and industry group were all significant factors influencing corporate social reporting patterns in the accounting sector. Analysis shows that Chinese accounting firms are well behind the U.K. accounting firms with regard to website corporate social disclosure, while UK local accounting firms disclose less than the U.K. member firms of big international four. It further shows that the large international accounting firms adopt different disclosure policies in different regions with a much greater disclosure in the U.K. compared to China. Also UK accounting firms seem to report less on their corporation social responsibilities compared to other industries

ZNF750 is a lineage-specific tumour suppressor in squamous cell carcinoma.

ZNF750 controls epithelial homeostasis by regulating epidermal-differentiation genes, a role underscored by its pathogenic mutations in esophageal squamous cell cancers (SCCs). However, the precise role of ZNF750 in SCC cell biology remains unclear. In this study, we report that ZNF750 is exclusively deleted, mutated and underexpressed in human SCCs, and low ZNF750 expression is associated with poor survival. Restoration of wildtype, but not mutant ZNF750 protein uniquely inhibited the malignant phenotypes of SCC cells both in vitro and in vivo. Notably, ZNF750 promoted the expression of a long non-coding RNA (TINCR), which mediated both cancer-inhibition and differentiation-induction effects of ZNF750. In addition, ZNF750 potently suppressed cell migration by directly inhibiting the transactivation of LAMC2. Together, our findings characterize ZNF750 as a crucial SCC-specific suppressor and uncover its novel anticancer-associated functions

Electroproduction of nucleon resonances

The unitary isobar model MAID has been extended and used for a partial wave analysis of pion photo- and electroproduction in the resonance region W < 2 GeV. Older data from the world data base and more recent experimental results from Mainz, Bates, Bonn and JLab for Q^2 up to 4.0 (GeV/c)^2 have been analyzed and the Q^2 dependence of the helicity amplitudes have been extracted for a series of four star resonances. We compare single-Q^2 analyses with a superglobal fit in a new parametrization of Maid2003 together with predictions of the hypercentral constituent quark model. As a result we find that the helicity amplitudes and transition form factors of constituent quark models should be compared with the analysis of bare resonances, where the pion cloud contributions have been subtracted.Comment: 6 pages Latex including 5 figures, Invited talk at ICTP 4th International Conference on Perspectives in Hadronic Physics, Trieste, Italy, 12-16 May 200