Fatigue life prediction of small notched Ti-6Al-4V specimens using critical distance

This study investigated the method of estimating the fatigue strength of small notched Ti-6Al-4V specimen using the theory of critical distance that employs the stress distribution in the vicinity of the notch root. Circumferential-notched round-bar fatigue tests were conducted to quantify the effects of notch radius and notch depth on fatigue strength. The fatigue tests show that the larger notch radius increases the fatigue strength and the greater notch depth decreases the fatigue strength. The theory of critical distance assumes that fatigue damage can be correctly estimated only if the entire stress field damaging the fatigue fracture process zone is taken into account. Critical distance stress is defined as the average stress within the critical distance from notch root. The region from the notch root to the critical distance corresponds to the fatigue fracture process zone for crack initiation. It has been found that a good correlation exists between the critical distance stress and crack initiation life of small notched specimens if the critical distance is calibrated by the two notched fatigue failure curves of different notch root radii. The calibrated critical distances did not vary clearly over a wide range of fatigue failure cycles from medium-cycle low-cycle fatigue regime to high-cycle fatigue regime and have an almost constant value. This critical distance corresponds to the size of crystallographic facet at the fatigue crack initiation site for the wide range of fatigue cycles.     

DFT时代的ATE结构--多端口ATE

在单颗硅芯片上设计更多系统功能(SOC)的趋势,增加了IC的开发与制造测试的复杂度。未来对于较高速度与较多管脚数的需求,将使传统的自动化测试仪器(ATE)变得非常昂贵。为了减轻开发工作的负担及降低制造测试的成本,不得不寻求知识产权(IP)的再利用与可测试性设计(DFT)技术。本文介绍一种新的多端口ATE结构,它是为基于IP的测试开发与执行而设计的。这种结构提供刚好足够的能力来测试芯片,以降低ATE的资本成本,并广泛使用平行测试来提高产能。     

Effects of water-soluble carbohydrate content on silage fermentation of wheat straw

To determine a suitable initial water-soluble carbohydrate (WSC) content to make wheat straw natural fermentation successful and to study fermentation characteristics, glucose was used to adjust the initial WSC content to 1.4%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, and 10.0% dry matter (DM) in the wheat straw. At 30 d of fermentation, there were three pHs: when the initial WSC content was 1.4%, the pH was 5.5; when the initial WSC contents were 4.0%, 5.0% and 6.0%, the pHs were near 5.1; and when the initial WSC contents were 7.0%, 8.0%, 9.0% and 10.0%, the pHs were near 4.0. The pattern of changes in WSC content during the fermentation was similar to that in pH. At 30 d of fermentation, there existed a dividing line in WSC remnants between the initial 6.0% WSC treatment and the initial 7.0% WSC treatment. When the initial WSC content was more than 7.0%, the remaining WSC content was more than 23.7 g/kg DM. When the initial WSC content was less than 6.0%, the remaining WSC content was less than 13.6 g/kg DM. Particularly for the 1.4% WSC treatment, the remaining WSC content was 2.1 g/kg DM. The results of the microbiological enumeration showed that with the increase in initial WSC content, the numbers of lactic acid bacteria (LAB) and other bacteria generally decreased. Denaturing gradient gel electrophoresis (DGGE) results showed that when the initial WSC content was beyond 7.0%, the LAB of the fermentation system were detected.     

High Dynamic Range Measurement with Arrayed Frequency Converter

When measuring multicarrier communication systems such as an orthogonal frequency division multiplexing (OFDM) or UWB wireless signal, there is a problem that the effective measuring dynamic range of the measuring instrument may be reduced, since the peak‐to‐average power ratio (PAPR) of the measured signal is significantly high. In order to solve this problem, we propose a technique that maintains the measuring dynamic range by dividing the measured signal into multiple bandwidths to decrease the measured signal power. We made a prototype of the measuring equipment, confirmed the operation of the algorithm, and verified the effectiveness of dynamic range improvement is 5 to 8 dB in relation to a conventional circuit. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(2): 28–35, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22367     

Formation, sintering, and electrical conductivity of (Nd1−xCax)CrO3 (0≤x≤0.25) using citric acid as a gelling agent

In Ca²⁺-substituted NdCrO₃, single-phase perovskite compounds (Nd_1−xCa_x)CrO₃, where x=0-0.25, have been formed by a citric acid processing. (Nd_1−xCa_x)CrO₃ powders consisting of submicrometer-size particles are sinterable; dense materials can be fabricated by sintering for 2 h at 1700°C under atmospheric pressure. The relative densities, grain sizes, and electrical conductivities increase with increased Ca²⁺ content. (Nd_0.75Ca_0.25)CrO₃ materials show an excellent electrical conductivity of 1.9×10 S m⁻¹ at 1000°C.     

The effects of external stress on the cubic-tetragonal transformation in rapidly quenched ZrO2-Y2O3

The effects of the external stress on the displacive cubic (c) to tetragonal (t) transformation, taking place during rapid quenching of ZrO₂-Y₂O₃ alloys by a hammer-anvil unit, were examined through the statistical analysis of the crystallography of the product phases. The initially formed c-phase had no strong texture with respect to the stress direction. However, specific t variants among crystallographically equivalent ones were formed preferentially. From these observations, it is concluded that the applied stress plays an important role on the deformation to change the lattice during the c t transformation.