681 research outputs found
Nomenclatural changes for selected Mordellidae (Coleoptera) in North America
New nomenclatural changes are presented for selected North American mordellid beetles (Coleoptera: Mordellidae). The following five genera are newly recorded fi.·om the United States: Mordellaria Ermisch 1950, Falsomordellistena Ermisch 1941, Mordellina Schilsky 1908, Mordellochroa Emery 1876, and
Pseudotolida Ermisch 1950. The following species are transferred from Tomoxia and represent new combinations: Mordellaria borealis (LeConte 1862), Mordellaria fascifera (LeConte 1878), Mordellaria latipalpis (Ray 1946), Mordellaria serval (Say 1835), and Mordellaria undulata (Melsheimer 1845). The following species are transferred fi.·om Mordellistena and represent new combinations: Falsomordellistena hebraica (LeConte 1862) and Falsomordellistena pubescens (Fabricius 1798); Mordellina blatchleyi (Liljeblad 1945), Mordellina pilosella (Ray 1947), Mordellina pustulata (Melsheimer 1845), Mordellina ustulata (LeConte 1862), and Mordellina wichhami (Liljeblad 1945); Mordellochroa scapularis (Say 1824); Pseudotolida
arida (LeConte 1862), Pseudotolida hnausi (Liljeblad 1945), and Pseudotolida lutea (Melsheimer 1845). Mordellina ustulata (LeConte 1862) represents a return to species rank after being treated as a subspecies of Mordellistena andreae LeConte 1862. There are a total of 17 genera of Mordellidae in America north of Mexico
A feasibility study of wind turbine blade surface crack detection using an optical inspection method
A new image processing technique was investigated to assess its ability to detect surface flaws on an on-tower wind turbine blade (WTB). The method was tested by varying the parameters of the surface flaws as well as the parameters of the method. It was found that detecting and quantifying cracks as small as hair thickness with computer-based optical inspection is feasible and the orientation of a crack was not sensitive to image processing so that the inspection camera does not need to be set up at a specific angle to detect cracks. It was also found that uneven background illumination was significantly reduced by optimizing the threshold value using the Canny method. In addition, the accuracy of quantifying a crack was improved by reducing noise with the intersection of two processed images from Sobel and Canny methods
Feasibility of Automatic Detection of Surface Cracks in Wind Turbine Blades
Cracks on the surface of a wind turbine blade (WTB) can be a sign of current or future damage to the underlying structure depending on the severity of the cracks. We investigated a new method for automatically detecting surface cracks based on image processing techniques. The method was evaluated by varying crack parameters and our method parameters. Identifying and quantifying cracks as small as hair thickness is possible with this technique. Orientation of a crack did not affect the results. The effects of uneven background illumination (present in images captured on-tower) were significantly reduced by optimizing the threshold value for the Canny edge detection method. The accuracy of quantifying a crack was increased by processing an image with both the Sobel and Canny edge detection methods and then combining the results to reduce background noise
Detecting Inconsistency in Functional Software Requirements
Success in software development depends on the availability of complete, consistent, and unambiguous functional software requirements. Inconsistencies in software requirements can propagate problems throughout the development cycle. We introduce the concept of a quantitative measure for detecting inconsistencies, namely, Potential Structural Inconsistency (PSI). This measure is derived from a structural model for a given set of requirements. We show how this measure can be determined using a case study with known inconsistencies
Form Error Estimation Using Spatial Statistics
Form error estimation is an essential step in the assessment of product geometry created through one or more manufacturing processes. We present a new method using spatial statistics to estimate form error. Using large sets of uniform sample points measured from five common machined surfaces, we compare the form error estimates using individual points and fitted surfaces obtained through spatial statistical methods. The results show that spatial statistics can provide more accurate estimates of form error under certain conditions
A Probabilistic View of Problems in Form Error Estimation
Form error estimation techniques based on discrete point measurements can lead to significant errors in form tolerance evaluation. By modeling surface profiles as random variables, we show how sample size and fitting techniques affect form error estimation. Depending on the surface characteristics, typical sampling techniques can result in estimation errors of as much as 50 percent. Another issue raised in the fitting approach is the metric p selection for the fitting objective. We show that for p = 2 and p = ∞, the selection does not appear to significantly affect the estimation of form error
Keys and Notes on the Buprestidae (Coleoptera) of Michigan
The distribution and dates of adult activity for Michigan buprestids are discussed. Keys to the genera and species, as well as host information are presented for 116 species and one subspecies. Information on collecting techniques, illustrations of genitalia of 14 species, and scanning electron micrographs of certain structures useful in species identification are presented and discussed. In addition, Pachyschelus confusus, a new species, is described from bush clover
Engineering Economic Valuation of Ready-Made Design for Transportation Vehicles
Nowadays, transportation vehicles are upfront equipped with fuel saving devices such as winglets in airplanes so as to reduce fuel consumption. By ready-made design, we mean this approaching of equipping upfront on transportation vehicles. In this article, under the reasonable assumption that the fuel cost is volatile and follows a geometric Brownian motion (GBM) process, we use the theory of stochastic optimal control (1) to determine the threshold of fuel cost to decommission such a transportation vehicle, and (2) to determine the engineering economic valuation of such a design. For the threshold and the valuation, we proceed to obtain the analytical solutions to our approach, followed by sensitivity analyses as well as the derivation of the total expected operation lifetime until decommissioning. Finally, for the managerial insights and economic implications, we present an extensive numerical example with numerous empirical data sets from publicly available sources. For instance, as the fuel cost becomes more uncertain, economically rational decision makers will defer the decommissioning of a vehicle
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