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31.
32.
Min Zhang Yiming Peng Anna Schuh Fadel M. Megahed William H. Woodall 《Quality and Reliability Engineering International》2013,29(2):209-223
The geometric control chart has been shown to be more effective than p and np‐charts for monitoring the proportion of nonconforming items, especially for high‐quality Bernoulli processes. When implementing a geometric control chart, the in‐control proportion nonconforming is typically unknown and must be estimated. In this article, we used the standard deviation of the average run length (SDARL) and the standard deviation of the average number of inspected items to signal, SDARL*, to show that much larger phase I sample sizes are needed in practice than implied by previous research. The SDARL (or SDARL*) was used because practitioners would estimate the control limits based on different phase I samples. Thus, there would be practitioner‐to‐practitioner variability in the in‐control ARL (or ARL*). In addition, we recommend a Bayes estimator for the in‐control proportion nonconforming to take advantage of practitioners' knowledge and to avoid estimation problems when no nonconforming items are observed in the phase I sample. If the in‐control proportion nonconforming is low, then the required phase I sample size may be prohibitively large. In this case, we recommend an approach to identify a more informative continuous variable to monitor. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
33.
The feasibility of maintenance processes relies on the availability of spare parts. Spare part inventory planning is capital intensive. It is based on demand forecasting, which possesses a high potential in reducing inventories. Even if condition monitoring systems are installed in technical systems, condition monitoring information is barely used to predict the failure probability of units. Therefore, an enhanced forecast model, which integrates SCADA information, has been developed. This leads to more accurate spare part demand forecasts. The approach presented in the paper is based on data mining, the proportional hazards model (PHM) and a binomial distribution. It has been validated with maintenance data of wind energy systems. 相似文献
34.
Thomas Richter Stefan Denneler Carsten Schuh Ender Suvaci Ralf Moos 《Journal of the American Ceramic Society》2008,91(3):929-933
A promising way to improve the performance of piezoelectric ceramics is grain orientation by templated grain growth. In this work lead-based piezoelectric ceramics Pb(Mg1/3 Nb2/3 )0.68 Ti0.32 O3 (PMN–32PT) and Pb(Mg1/3 Nb2/3 )0.42 (Ti0.638 Zr0.362 )0.58 O3 (PMN–37PT–21PZ) ceramics were textured via templated grain growth process. For texturization (001)-oriented BaTiO3 (BT) platelets (approximately 10 μm × 10 μm × 2 μm) were utilized as templates. The texturized ceramics were accomplished by aligning the templates by tape casting. The template growth into the matrix resulted in textured ceramics with Lotgering factors between 0.94 and 0.99 for both compositions. Consequences of the texture are enhanced dielectric and piezoelectric properties. Unipolar strain-field measurements of textured ceramics showed 0.25% strain s 33 at 3 kV/mm. Large signal d 33 * of up to 878 pm/V were determined directly from strain measurements. Compared with randomly oriented ceramics in texturized samples unipolar strain s 33 and large signal d 33 * was enhanced by a factor of up to 1.8. 相似文献
35.
Copper‐based shape memory alloys (SMAs) exhibit excellent shape memory properties in single crystalline form. However, when they are polycrystalline, their shape memory properties are severely compromised by brittle fracture arising from transformation strain incompatibility at grain boundaries and triple junctions. Oligocrystalline shape memory alloys (oSMAs) are microstructurally designed SMA structures in which the total surface area exceeds the total grain boundary area, and triple junctions can even be completely absent. Here it is shown how an oligocrystalline structure provides a means of achieving single crystal‐like SMA properties without being limited by constraints of single crystal processing. Additionally, the formation of oSMAs typically involves the reduction of the size scale of specimens, and sample size effects begin to emerge. Recent findings on a size effect on the martensitic transformation in oSMAs are compared and a new regime of heat transfer associated with the transformation heat evolution in these alloys is discussed. New results on unassisted two‐way shape memory and the effect of loading rate in oSMAs are also reported. 相似文献
36.
The fabrication of multilayer assemblies from polymeric compounds is an important tool for precise control of film architecture on the nanoscale. In this report, a general, novel approach for the preparation of well‐defined polymeric multilayers is described. To achieve this, sulfonyl‐azide group containing polymers are first generated and deposited as thin films onto solid (organic) substrates. Upon thermal activation, the system crosslinks and binds to the substrate via C–H bond insertion. Through step‐and‐repeat procedures, multilayer assemblies are then generated where all the individual layers are linked to each other. As the assembly process does not require any specific molecular interactions, the described process represents a general strategy to generate tailor‐made multilayer surface coatings with wide range of film thickness and composition. 相似文献
37.
Thomas Richter Carsten Schuh Ender Suvaci Ralf Moos 《Journal of Materials Science》2009,44(7):1757-1763
Single crystal growth of lead-based piezoelectric ceramics Pb(Mg1/3Nb2/3)0.68Ti0.32O3 (PMN-32PT) and Pb(Mg1/3Nb2/3)0.42(Ti0.638Zr0.362)0.58O3 (PMN-37PT-21PZ) ceramics via templated grain growth (TGG) was investigated. (001)- and (111)-oriented BaTiO3 (BT) single crystals and (001)-oriented SrTiO3 (ST) single crystals (of approximately 2.5 × 2.5 × 1 mm) were utilized as seeds for the growth experiments. The piezoelectric
single crystals were produced in a process that involves at first hot pressing of single crystal in cold isostatically pressed
ceramics followed by subsequent sintering of the samples. Growth of (001)-oriented single crystals with BT seeds was observed
in both PMN-32PT and PMN-37PT-21PZ matrices. The measured growth lengths were up to 140 and 65 μm, respectively. The grown
(001)-oriented single crystals grown were rectangular. The measured growth lengths of the pyramidal-shaped (111) BT single
crystals were up to 1 mm, which is much larger than the growth lengths of the (001) single crystals. Experiments on (001)
ST-seeded single crystals were not successful. No single crystal growth was observed due to the dissolution of the ST single
crystals in the PMN-PZT matrix. The differences were explained by defect-chemical considerations. 相似文献
38.
Pientschke C. Steinhausen R. Beige H. Kruger R. Muller T. Sporn D. Schuh C. Denneler S. Schlich H. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2009,56(9):1806-1812
Using the sol-gel process, Nd-Mn-doped PZT fibers were produced. The PZT was doped with 2 mol% neodymium and 1.1 mol% manganese. For characterization, the fibers were embedded in a polymer. The resulting 1-3 composites were poled with constant electric field. Strain and polarization were measured by applying a bipolar sinusoidal voltage of high amplitude. Instead of the expected shifted butterfly-shaped strain hysteresis, an asymmetric strain-field relation was observed. It is characterized by a rather linear region in direction of the poling field and an inflated region without strain switching for reversed polarity. Within the temperature range from room temperature to 80degC, the strain switching seems to be suppressed. Measurements of the piezoelectric coefficient at superimposed electric field prove the blocking of strain switching. Cyclation experiments with sesquipolar load show a pronounced linearity of the strain loops that declines after more than 2 times 104 cycles. 相似文献
39.
R Koslowski LG Dobbs KW Wenzel D Schuh M Müller M Kasper 《Canadian Metallurgical Quarterly》1998,12(6):1397-1403
After lung injury, the epithelial cells lining the alveolar surface in rat lung show an altered distribution of several membrane proteins. Pulmonary fibrosis was induced by intratracheal administration of bleomycin into the lung of rats and the distribution of RTI40, a recently detected alveolar epithelial type I cell antigen, was examined, as well as the relationship between RTI40 and a type I cell-specific antigen recognized by the monoclonal antibody MEP-1 and the type I cell-binding lectin Bauhinia purpurea in serial sections and double stainings. Loss of RTI40 protein was observed in fibrotic lungs, particularly in areas with obliteration of alveoli. Pre-embedding immunoelectron microscopy confirmed this observation by detection of RTI40 protein in the alveolar lumen. Western blot analysis revealed elevated levels of RTI40 in the bronchoalveolar fluid of bleomycin-treated rats with a maximum at day 7 after treatment. Twenty-eight days after bleomycin application, the bronchoalveolar fluid contained three times the amount of RTI40 x mg protein(-1) of control lungs, as determined by semiquantitative dot blot. These results suggest RTI40 as a tool for the evaluation of alveolar epithelial type I cell behaviour during re-epithelialization processes. 相似文献
40.
The LSP test method was used to compare various surface treatments of spinal rods for dorsal spine implant systems. This test method allowed a fast testing. Result were given after one or two weeks in comparison to 6 to 8 months. Rods made of two different cp‐Titanium materials ( Ti‐2 and Ti‐4) were tested. Best results with a LSP value of 167 Mio. were achieved with Ti‐4 material, shot peened with steel balls and glass beads. In comparison the lowest LSP value showed 81 Mio with Ti‐2 material shot peened with glass beads only. This kind of high speed testing reduced the typical development period from two years to at least 6 months. 相似文献