The effects of film thickness variations on the residual stress distributions in coated Cr thin films

Generally, the residual stress of thin film coatings is calculated using Stoney's equation. However, variables in the manufacturing of the coated film, such as crystalline particle size and the unevenness of the thickness of the film, cause the radius of curvature of the beam to vary all over the beam. The cantilever beam curves not only in the axial direction but also in the transverse direction. Therefore, the residual stress in a film coating comprises not only axial residual stress but also transverse residual stress, and its distribution is also not uniform. Under such conditions, Stoney's equation must be modified. In this study, Si was used as a substrate in the production of cantilever beam specimens. Chromium thin films of various thicknesses were coated onto the Si substrates. The 3D digital image correlation technique was used to measure the out‐of‐plane displacement of the specimens at various positions. Then the modified Stoney's equation was used to obtain the axial and transverse residual stress at each measurement point to study the effect of variations in the thickness of the thin film on the magnitude and uniformity of the distribution of the residual stresses. Three thin film thicknesses 1, 2, and 3 μm were studied, and three specimens for each thickness were used. For each specimen, axial and transverse residual stresses were obtained at nine test points, and the equivalent residual stress was calculated. The results of this study reveal that as the difference between the thicknesses of the coating increased, average equivalent residual stress decreased and the distribution of stresses became more uniform. By comparing the corresponding results for the 1‐ and 3‐μm‐thick films revealed that the confidence levels in the average value and uniformity of the equivalent residual stress distribution, which increased with thickness, were 92.81% and 80.57%, respectively.     

A Novel Lot Sentencing Method by Variables Inspection Considering Multiple Dependent State

A good acceptance sampling plan is necessary for quality control, and different acceptance sampling plans have been developed to meet different purposes. Under a multiple dependent state (MDS) sampling plan, the lot disposition is not only based on the current sample from the lot but also on the sample results from preceding lots. This paper aims to develop a variables MDS sampling plan for normally distributed processes with two‐sided specification limits. In the proposed MDS sampling plan, the operating characteristic curve is derived based on the exact sampling distribution. The performance of the proposed plan is investigated and compared with the existing variables single sampling plan. Copyright © 2015 John Wiley & Sons, Ltd.     

Dual open‐slot antennas integrated in metal frame and metal case of tablet computer for long‐term evolution applications

Dual open‐slot antennas were integrated in the metal back case and metal frame of a tablet computer for long‐term evolution applications. The single feed dual excitation source antennas were sufficiently narrow (2 mm) for installation between the metal frame and metal back case of the tablet computer. Each antenna had two open‐slot radiators (slot 1 and slot 2) with embedded filter circuits to enable wideband (699‐906 and 1710‐2690 MHz) operation required for LTE applications. The filter circuit values were adjusted to make the impedance more smooth and excite the desired modes. The proposed multiple‐input‐multiple‐output antennas were installed lengthwise on the long sides of the tablet and facing in operate directions. In this configuration, the user hand grip did not interfere with antenna performance, and isolation was improved (> 20 dB). The operating mechanism of the proposed antenna with matching circuits is described in detail. The effects of the user hand grip and the embedded display panel are also discussed.     

Thermal deformation of microstructure diffuser plate in LED backlight unit

Thermal deformations of a microstructure diffuser plate in an LED backlight unit subjected to a long period of illumination were studied. Mechanical properties of the microstructure diffuser plate in the LED backlight unit were determined and verified. Rather than using data from the relevant literature, accurate finite element solutions were obtained by using a microtensile test and thermo‐mechanical analyzer to calculate the Young's modulus, Poisson's ratio, and thermal expansion coefficient of the microstructure diffuser plate. The measured mechanical properties were used as input data in finite element simulations. Comparisons of the finite element analysis results with the experimental measurements made using strain gauge yielded differences of less than 3%. Thermal warpage phenomena of the microstructure diffuser plate at various temperatures are discussed. Thermal deformations are also compared between the conventional diffuser plate and the microstructure diffuser plate.     

基于作物需水的灌溉用水量核算方法及应用

用水量核算方法是最严格水资源管理制度实施的一项技术支撑。以山东济宁市梁山县为研究区,采用FAO(国际粮农组织)推荐的Penman-Monteith公式,计算了该县3种主要农作物的逐日作物需水量及净灌溉需水量。研究中考虑到研究区的作物种植面积、灌溉水利用系数等因素提出理论需水量和折算系数的概念,通过推求理论需水量与实际用水量的折算系数,对2011年和2012年梁山县灌溉用水量统计数据进行核算,核算的相对误差分别为0.08%和-1.52%,核算结果较好。     

旋流环形堰竖井泄洪洞三维流场数值模拟

旋流环形堰竖井泄洪洞是一种新型的环境友好的内消能工, 跟传统环形堰竖井泄洪洞相比, 泄洪洞的流态和 消能防蚀机理明显不同。作为一种新型布置形式, 其复杂的水流特性并不是十分清楚。依托于广东清远抽水蓄能 电站下水库泄洪洞工程, 基于RNG k2E双方程湍流数学模型, 并结合VOF( Volume Of Fluid) 方法, 对下库旋流环形 堰竖井泄洪洞进水口、竖井旋流泄洪洞、出口的复杂水流进行了三维数值模拟, 并对部分水力参数的特性进行了解 析计算, 获得了流态、压力、流速、空化数等水力要素的变化规律。模拟结果表明, 数值计算结果与物理模型试验成 果吻合较好。并通过数值模拟验证了该新型内消能工的泄流能力和高消能效率。     

A novel size-dependent nonlocal strain gradient isogeometric model for functionally graded carbon nanotube-reinforced composite nanoplates

The paper presents a novel nonlocal strain gradient isogeometric model for functionally graded carbon nanotube-reinforced composite (FG-CNTRC) nanoplates. To observe the length scale and size-dependency effects of nanostructures, the nonlocal strain gradient theory (NSGT) is considered. The present model is efficient to capture both nonlocal effects and strain gradient effects in nanoplate structures. In addition, the material properties of the FG-CNTRC are assumed to be graded in the plate thickness direction. Based on the higher order shear deformation theory (HSDT), the weak form of the governing equations of motion of the nanoplates is presented using the principle of virtual work. Afterward, the natural frequency and deflection of the nanoplates are made out of isogeometric analysis (IGA). Thanks to higher order derivatives and continuity of NURBS basic function, IGA is suitable for the weak form of NSGT which requires at least the third-order derivatives in approximate formulations. Effects of nonlocal parameter, strain gradient parameter, carbon nanotube (CNT) volume fraction, distributions of CNTs and length-to-thickness ratios on deflection and natural frequency of the nanoplates are examined and discussed in detail. Numerical results are developed to show the phenomenon of stiffness-softening and stiffness-hardening mechanisms of the present model.

     

Effect of antacid on bioavailability of a sustained-release theophylline preparation

The effect of coadministration of an antacid on bioavailability of a sustained-release theophylline tablet preparation (Theo-Dur) was studied by crossover comparison in five young, healthy, nonsmoking volunteers. Water 90 ml, or "high potency" aluminum-magnesium hydroxide antacid (Mylanta II) 10 ml and water 80 ml were administered concurrently with sustained-release theophylline 600 mg. Eleven blood samples were collected over the next 24 hours. Serum was analyzed with high pressure liquid chromatography technique to determine theophylline concentration. Peak serum concentration (Cmax) and time to peak concentration (tmax) were determined, and area under the 24-hour serum concentration-time curve (AUC) was calculated by the trapezoidal rule for each subject at each study interval. The Student's paired t-test was used to compare Cmax, tmax, and AUC for both treatments. A uniform difference was found between groups in Cmax. Cmax was higher in subjects when treated with the antacid (10.45 +/- 3.03 vs. 8.30 +/- 2.90 micrograms/ml, p less than 0.05) than when given theophylline alone. The mean tmax for the two treatments did not differ (10.4 +/- 1.67 h-combination vs. 10.8 +/- 1.1 h-theophylline, p greater than 0.05). Likewise, mean AUC was unchanged by the coadministration of antacid (140.65 +/- 41.6 micrograms/ml.h--combination vs. 155.13 +/- 46.6 micrograms/h--theophylline, p greater than 0.05). The use of a high-potency antacid product did not decrease the extent of theophylline absorption from this sustained-release product, but did increase Cmax and, presumably, rate of absorption. High-potency aluminum-magnesium antacids can probably be used in combination with this sustained-release theophylline tablet without detriment to therapy.     

Suicidal age and childhood onychophagia among psychotic veterans

The relationship between childhood onychophagia (fingernail biting) and the suicidal and nonsuicidal mean age among 150 hospitalized psychotic veterans was investigated. The results show that the suicidal mean age is significantly younger than the nonsuicidal mean age and that the childhood onychophagia variable "focal suicide" significantly lowers the mean age of suicidal veterans, but does not significantly lower the mean age of nonsuicidal veterans.