总被引：2，自引：0，他引：2  

Ahmed Z. Al‐Garni  Ahmad Jamal 《Quality and Reliability Engineering International》2011,27(2):209-219

This paper presents an application of artificial neural network (ANN) technique for conducting the reliability analysis of Boeing 737 tires. For this purpose, an ANN model utilizing the feed‐forward back‐propagation algorithm as a learning rule is developed. The inputs to the neural network are the flight operational time and the number of landings as independent variables and the output is the failure rate of the tires. Two years of data are used for failure rate prediction model and validation. Model validation, which reflects the suitability of the model for future predictions, is performed by comparing the predictions of the model with that of Weibull regression model. The results show that the failure rate predicted by the ANN is closer in agreement with the actual data than the failure rate predicted by the Weibull model. The present work also identifies some of the common tire failures and presents representative results based on the established model for the most frequently occurring tire failure. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

    

Dae‐Heung Jang  Christine M. Anderson‐Cook 《Quality and Reliability Engineering International》2011,27(1):27-34

When the component proportions in mixture experiments are restricted by lower and upper bounds, the design space can become an irregular region that can induce multicollinearity among the component proportions. Thus, we suggest the use of ridge regression as a means of stabilizing the estimates of the coefficients in the fitted model. We use fraction of design space plots and violin plots to illustrate and evaluate the effect of ridge regression estimators with respect to the prediction variance and to guide the decision about the value of ridge constant k. We illustrate the methods with three examples from the literature. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

    

DoSik Hwang  Jeong‐Whan Lee  Gengsheng L. Zeng 《International journal of imaging systems and technology》2011,21(3):247-252

Described herein are the advantages of using sub‐sinograms for single photon emission computed tomography image reconstruction. A sub‐sinogram is a sinogram acquired with an entire data acquisition protocol, but in a fraction of the total acquisition time. A total‐sinogram is the summation of all sub‐sinograms. Images can be reconstructed from the total‐sinogram or from sub‐sinograms and then be summed to produce the final image. For a linear reconstruction method such as the filtered backprojection algorithm, there is no advantage of using sub‐sinograms. However, for nonlinear methods such as the maximum likelihood (ML) expectation maximization algorithm, the use of sub‐sinograms can produce better results. The ML estimator is a random variable, and one ML reconstruction is one realization of the random variable. The ML solution is better obtained via the mean value of the random variable of the ML estimator. Sub‐sinograms can provide many realizations of the ML estimator. We show that the use of sub‐sinograms can produce better estimations for the ML solution than can the total‐sinogram and can also reduce the statistical noise within iteratively reconstructed images. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 247–252, 2011;  相似文献   

    

Maurus Biedermann  Jan‐Erik Ingenhoff  Martino Barbanera  Davide Garbini  Koni Grob 《Packaging Technology and Science》2011,24(5):281-290

From the toxicological evaluation of mineral oils as used in offset printing inks by the Joint Food and Agriculture Organization of the United Nations/World Health Organization Expert Committee on Food Additives (JECFA), a specific migration limit of 0.6 mg/kg in food can be derived. Experimental packs for taglioline (fine noodles) were investigated, aiming at respecting this limit. This ended with four conclusions. First, during the 65 day test (shelf life of 2 years), the transport box of corrugated board contaminated the bottom packs in the box with 6.1 mg/kg mineral oil saturated hydrocarbons (MOSH) and had the potential of contaminating all the 10 packs on average at about 10 mg/kg. Second, the migration from an improved recycled paperboard (five times less mineral oil than average) still amounted to 4.9 mg/kg, indicating that optimization of recycling is not promising to respect the 0.6 mg/kg limit. Third, a printing ink containing 3 g/kg MOSH (about 100 times less than conventional offset inks) still contaminated the taglioline with 0.6 mg/kg MOSH. Finally, the taglioline were contaminated with 2.5 mg/kg MOSH already before packing, illustrating that there are other sources of mineral oil violating the 0.6 mg/kg limit. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

    

Zi‐Cai Li  John Y. Chiang  C. Y. Suen 《International journal of imaging systems and technology》2011,21(4):323-335

For digital images and patterns under the nonlinear geometric transformation, T: (ξ, η) → (x, y), this study develops the splitting algorithms (i.e., the pixel‐division algorithms) that divide a 2D pixel into N × N subpixels, where N is a positive integer chosen as N = 2 ^k(k ≥ 0) in practical computations. When the true intensity values of pixels are known, this method makes it easy to compute the true intensity errors. As true intensity values are often unknown, the proposed approaches can compute the sequential intensity errors based on the differences between the two approximate intensity values at N and N/2. This article proposes the new splitting–shooting method, new splitting integrating method, and their combination. These methods approximate results show that the true errors of pixel intensity are O(H), where H is the pixel size. Note that the algorithms in this article do not produce any sequential errors as N ≥ N₀, where N₀ (≥2) is an integer independent of N and H. This is a distinctive feature compared to our previous papers on this subject. The other distinct feature of this article is that the true error bound O(H) is well suited to images with all kinds of discontinuous intensity, including scattered pixels. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 323–335, 2011  相似文献   

    

H.A. Abd El‐Rahman  S.A. Salih  A. M. Abd El‐Wahab 《Materialwissenschaft und Werkstofftechnik》2011,42(9):784-791

Effect of phosphoric acid on the performance of Pb‐1.7%Sb grid of lead‐acid cell is studied in 5 M H₂SO₄ by cyclic galvanostatic polarization and impedance spectroscopy. An increase in capacitance to a maximum is recorded during the initial stages of the electro‐reduction of PbO₂ into Pb(II) compounds and attributed to concurrent compositional and dimensional changes. These changes include removal of O₂ bubbles, insertion of large amounts of H₂SO₄ and H₂O. Efficiency of PbO₂ formation decreases, while its rate of self‐discharge increases with increasing the charging current and in the presence of H₃PO₄. The charge capacity increases with increasing the discharging current due to the decrease in the self‐discharge. The charge capacity is lower in the presence of H₃PO₄. On increasing the cycle number, the corrodibility of the grid increases, because more layers of the surface Pb are involved in the self‐discharge. H₃PO₄ significantly retards the effect of cycle number.  相似文献   

    

C. Hübsch  M. Erne  K. Möhwald  Fr.‐W. Bach  M. Bretschneider  M. Kästner  E. Reithmeier 《Materialwissenschaft und Werkstofftechnik》2011,42(6):519-530

In this paper microstructures have been produced with a stochastic distribution by a thermal spraying process with different process parameters. An optical roughness measurement device has been used to measure these microstructures. Afterwards the measurement data is processed in order to identify each microstructure. Using this data several characteristics like the area, the volume and the depth of the microstructures as well as several porosities have been computed. These characteristics could be correlated to the process parameters. Furthermore, tribological experiments have been conducted with these surfaces and additional correlations between the friction value and the characteristics area, depth and the average roughness besides the structures have been performed.  相似文献   

    

B.‐A. Behrens  K.‐G. Kosch 《Materialwissenschaft und Werkstofftechnik》2011,42(11):973-978

In times of increasing energy costs automotive light weight construction is gaining more importance. The production of hybrid compounds by forging is a promising method for manufacturing functional parts by applying resource‐saving process steps. The mechanical properties of these parts can be specifically adapted to the requirements. In compound forging of steel‐aluminum parts the two materials need to be heated to different forming temperatures. In this paper, the challenges and their methods for the development of a heating and forming strategy based on different material characteristics are presented.  相似文献   

    

Jiangtao Zhu  Sie Chin Tjong  Xiao‐Qiang Li 《Advanced Engineering Materials》2010,12(11):1161-1165

Hydroxyapatite (HA) and its nanocomposites reinforced with low loading levels of multiwalled carbon nanotubes (MWNTs) are prepared by spark plasma sintering process. The structure, morphology, and hardness of sintered HA and MWNT/HA nanocomposites are characterized by means of X‐ray diffraction (XRD), scanning electron microscopy and nanoindentation techniques. XRD results show that the orientation of crystallographic planes of sintered HA are highly related to the applied pressure direction. The perpendicular section of sintered MWNT/HA nanocomposites shows predominantly oriented HA a‐and b‐planes while the parallel section displays a dominant c‐plane orientation. The hardness of MWNT/HA nanocomposites improves considerably with increasing MWNT content.  相似文献   

    

Sebastian F. Fischer M.Sc.  Marc Thielen  Ruth R. Loprang M.Sc.  Robin Seidel  Claudia Fleck  Thomas Speck  Andreas Bührig‐Polaczek 《Advanced Engineering Materials》2010,12(12):B658-B663

Natural materials often exhibit excellent mechanical properties. An example of outstanding impact resistance is the pummelo fruit (Citrus maxima) which can drop from heights of 10 m and more without showing significant outer damage. Our data suggest that this impact resistance is due to the hierarchical organization of the fruit peel, called pericarp. The project presented in the current paper aims at transferring structural features from the pummelo pericarp to engineering materials, in our case metal foams, produced by the investment casting process. The transfer necessitates a detailed structural and mechanical analysis of the biological model on the one hand, and the identification and development of adequate materials and processes on the other hand. Based on this analysis, engineering composite foam structures are developed and processed which show enhanced damping and impact properties. The modified investment casting process and the model alloy Bi57Sn43 proved to be excellent candidates to make these bio‐inspired structures. Mechanical testing of both the natural and the engineering structures has to consider the necessity to evaluate the impact of the different hierarchical features. Therefore, specimens of largely varying sizes have to be tested and size effects cannot be ignored, especially as the engineering structures might be upscaled in comparison with the natural role model. All in all, the present results are very promising: the basis for a transfer of bio‐inspired structural hierarchical levels has been set.  相似文献