Advanced evaluation of thermal ratchetting of FBR components

A new prediction method for the thermal ratchetting of a cylinder subjected to an axially moving temperature distribution is proposed in this paper. This ratchetting is quite different from the conventional Bree-type ratchetting, and an advanced evaluation method has been required in the structural design of FBR components. The proposed method considers the work hardening of actual materials for FBR components. Firstly the basic scheme of the prediction method is shown, and secondly the application procedure to the actual design is shown. Predicted results by using this method coincide well with experimental results, when compared with the case by using the previous method.     

Full scale investigation of GCL damage mechanisms in small earth dam retrofit applications under earthquake loading

This paper reports results of full scale testing to further explore potential GCL damage mechanisms in earth dam retrofit applications in seismically active areas; in particular, to a) investigate whether shear displacements could reduce the magnitude of GCL panel overlap during earthquake shaking; b) explore the influence of gravel particles on GCL thickness at localised point of contact; and c) observe the consequences of an accidental exposure of an uncovered GCL to short duration rainfall in terms of moisture content and effects during subsequent compaction. The results of these experiments indicate that even under severe shaking no movements were detected at the GCL panel overlap. Whereas gravel particles were observed to locally reduce the thickness of the GCL to 2.2 mm, no plowing of the particle into the GCL occurred due to a lack of shear displacement at the interface, resulting in no localised internal erosion through the barrier. Furthermore, hydration of GCL panels during construction due to surface wetting was observed to result in a state of hydration less than its post-construction state. These results indicate that although each of the three GCL damage mechanisms cannot be ruled out to ever be relevant in practice, the performance of the GCL retrofitted earth dam tested was satisfactory under even severe Level 2 earthquake shaking, and suggests that the retrofitting of small earth dams with GCLs is a promising strategy to improve their static and seismic resistance.     

Transmission electron microscopic observations of nanobubbles and their capture of impurities in wastewater

Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly. We thus used a transmission electron microscope (TEM) with the freeze-fractured replica method to observe oxygen (O₂) MNBs in solutions. MNBs in pure water and in 1% NaCl solutions were spherical or oval. Their size distribution estimated from TEM images close to that of the original solution is measured by light-scattered methods. When we applied this technique to the observation of O₂ MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface.     

Determination of residual avoparcin in chicken muscle by HPLC with ultraviolet and amperometric detection

An analytical method was developed for determination of residual avoparcin in chicken muscle by measuring alpha- and beta-avoparcin, major components of the pharmaceutical preparation avoparcin, using HPLC with UV and amperometric detectors. The analytical HPLC was run on a Cosmosil 5C18-AR column (4.6 mm x 25 cm) with a gradient formed from A: 2.5% acetic acid, 0.01 mol/L sodium heptane sulfonic acid-acetonitrile (88.5:11.5) (pH 4.0) and B: 2.5% acetic acid-acetonitrile (10:90), using UV and amperometric detection (AMD) with glassy-carbon electrode (+900 mV). Avoparcin was extracted from chicken muscle by homogenization with methanol-0.2 mol/L sulfuric acid (6:4) followed by centrifugation after pH adjustment to 4 with 1 mol/L sodium hydroxide. The supernatant was evaporated to dryness, and the residue was dissolved in water. The aqueous layer was adjusted to pH 4 by adding 1 mol/L sodium hydroxide. Then it was purified on a Sep-Pak tC18 plus ENV cartridge. The cartridge was washed with water, and retained substances were eluted with 50% methanol. The eluate was evaporated to dryness under reduced pressure. The residue was dissolved in water and determined by HPLC. Recoveries of avoparcin spiked in chicken muscle were 73.1-88.1% at levels of 2-10 micrograms/g. The detection limits were 0.5 microgram/g (UV) and 0.2 microgram/g (AMD).     

Investigating the mechanism of downslope bentonite erosion in GCL liners using X-Ray CT

Exposed composite GMB-GCL liners are at risk of downslope bentonite erosion caused by the release of low ionic strength condensed water onto the top surface of the GCL following daily solar heating. This paper investigates the use of X-ray computed tomography (X-ray CT) to quantify the thinning of the bentonite layer and the application of X-ray diffraction techniques (XRD) to investigate the changes in clay chemistry (if any) of the bentonite from the virgin GCL to the eroded bentonite. The effect of specimen size and scanning orientation was investigated resulting in a revised testing procedure in which the CT scanning orientation was changed from horizontal to vertical to permit a longer test specimen which was also sealed at the bottom edge to minimise the edge boundary condition. The X-ray CT results provide highly visual evidence that a) bentonite thinning immediately under the upper cover geotextile is the initial location of erosion, and b) the bentonite core erodes at a significantly higher rate when not covered by a geotextile than when covered by a geotextile. These observations indicate that the upper geotextile of the GCL plays a significant role in controlling the rate of bentonite erosion. Finally, a comparison of the virgin and runoff bentonite properties was conducted to investigate potential changes in swell index, X-ray diffraction results, and concentration of Na and Ca cations. The runoff bentonite was observed to had a significantly higher swell index (40?ml/2?g) than the virgin bentonite (28?ml/2?g) and lower Na and Ca concentrations. This finding is consistent with the observation from XRD analyses of the runoff bentonite which illustrate that the clay fraction of the bentonite is preferentially eroded by the application of DI water.     

Performance evaluation of SOFC systems using electrochemical partial oxidation of methane

We simulated the performance of systems using a solid oxide fuel cell (SOFC) stack which generates electricity by electrochemical partial oxidation of methane and a conventional steam‐reforming‐type SOFC (SRSOFC) stack. The net thermal efficiency in an atmospheric partial‐oxidation‐type SOFC (POSOFC)‐SRSOFC system was 8% higher than that in an atmospheric SRSOFC system at system outputs of 35 kW or more. The net thermal efficiency of a pressurized POSOFC‐SRSOFC‐gas turbine (GT) system was slightly higher than that of a pressurized SRSOFC‐GT system. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(4): 11–19, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10314     

Error prevention in robotic assembly tasks by a machine vision and statistical pattern recognition method

Assembly errors can occur in a robotic assembly system. In this paper, a method that predicts an assembly error is proposed. It considers that assembly errors occur under the condition that the geometric trajectory of a mated part and the relational position and orientation of a base part are outside the allowable tolerance. A certain point, which is determined by using a physical light reflectance model of a mated part, is followed with two high-speed cameras. A statistical pattern recognition method in which explanatory variables are tracked points in a three-dimensional space is then employed to predict an assembly error. The proposed method is applied to a peg-in-a-hole assembly by a selective compliance assembly robot arm (SCARA)-type robot and its potential value is discussed.     

A vortex-lattice method in the linear theory on a two-dimensional supercavitating flat plate foil

The vortex-lattice method has been found very satisfactory in the case of steady subsonic wing theory, however, the discrete numerical methods, such as the vortex-lattice method, have not been studied in detail for supercavitating flows. One of the discrete numerical method, a vortex-lattice method, is developed in the present paper for cavitating flows around a two dimensional flat plate foil. The governing equations in the linear theory are represented as a set of coupled integral equations with Cauchy kernel, and there are unknown functions which are not under integral signs. For solving them, they are exchanged to an alternative set of coupled integral equations by a new variable, and the present vortex-lattice method is schemed for equal spacing of the vortices and sources in this new variable. The position of the collocation points is determined, and it is sufficient to treat unknown functions which are not integral signs as step functions. Moreover, the proof of the convergence of this method is shown and the accuracy is estimated.     

黄泛平原农村合理利用与开发生物质能的探讨——以山东省鄄城县糖牛楼村为例

对位于黄泛平原的山东省鄄城县糖牛楼村能源资源量与消费现状进行了调查，分析了该村能源的构成和消费特征，并进行了节能和开发新能源的实验，提高了生物质能利用率。