Curvature continuous path generation for autonomous vehicle using B-spline curves

In this paper we introduce a roadmap algorithm for generating collision-free paths in terms of cubic B-spline curves for unmanned vehicles used in mining operations. The algorithm automatically generates collision-free paths that are curvature continuous with an upper bounded curvature and a small slope discontinuity of curvature at knots, when we are given the locations of the obstacles, the boundary geometry of the working area, positions and directions of the vehicle at the start, loading, and the goal points. Our algorithm also allows us to find a switch back point where the vehicle reverses its direction to enter the loading area. Examples are provided to demonstrate the effectiveness of the proposed algorithms.     

Coarsening of hafnium carbide particles in tungsten

The coarsening behaviour of finely dispersed HfC particles in a W-HfC alloy was investigated by monitoring the growth rate of the particles. An activation energy of 480 kJ mol^–1 was obtained for the process. Diffusion experiments of hafnium in tungsten were conducted at temperatures between 1773 and 2573 K using a secondary ion mass spectroscopy technique to determine the diffusion contribution to the coarsening process. The diffusion process at high temperature is controlled by lattice diffusion with an activation energy of 335 kJ mol^–1 whereas that at low temperature is governed by grain-boundary diffusion with an activation energy of 170 kJ mol^–1. It appears that the coarsening process is controlled by two energy barriers: one dictated by the diffusivity of hafnium and the other by the solubility limit as a function of temperature. The strain energy required to dissociate the carbide particles into individual species was also considered. The effects of the coarsening of HfC particles in a dispersion-strengthened W-0.4 mol% HfC alloy on recrystallization and creep deformation were illustrated using a concerted experimental modelling analysis. Results show that the strengthening effect of the HfC particles is significantly reduced at temperatures above 1800 K, due to particle coarsening.     

Effect of fluorine contamination on barrier metal oxidation

We clarified that interfacial barrier metal oxidation with inter layer dielectric (ILD) could be revealed by X-ray photoelectron spectroscopy (XPS) on the peeled-side of the barrier metal, and the barrier metal oxidation was promoted by fluorine contamination which adsorb to the ILD surface during etching. To consider the effect of fluorine contamination on barrier metal oxidation, hydrolysable property of fluorine contamination was evaluated by measuring the change of F 1s spectrum after dipping in boiling water. Moreover, fluoride ions and the acidity of water in which fluorine contamination was dipped were measured by Ion chromatography and pH measurement, respectively. According to our experiments, it was suggested that hydrofluoric acid (HF) acted as an oxidizing catalyst to promote barrier metal oxidation at the interface of barrier metal and ILD.     

Surgical therapy for hepatocellular carcinoma with liver cirrhosis

Approximately 80% of hepatocellular carcinoma (HCC) patients in Japan have associated liver cirrhosis, which increases the difficulty of surgical treatment. Liver dysfunction associated with liver cirrhosis is one of the most important predictive prognostic factors for HCC patients. Percutaneous ethanol injection therapy (PEIT) is useful for patients with small HCC or with poor hepatic functional reserve. Transcatheter arterial chemoembolization (TACE) is also useful both for patients with unresectable HCC and patients with multiple intrahepatic recurrence. Liver resection, however, lead to better outcome than other treatments when liver function is maintained after surgery. To determine operative procedures, it is important to evaluate the exact function of remnant liver, based on the preoperative liver function test and the evaluation of tumor character. For advanced HCC patients with vascular invasion, non-surgical treatments such as PEIT or TACE are not indicated, and surgical intervention can be an effective modality to improve their survival. Improvements of surgical technique and perioperative management have decreased fatal complications at a major liver resection and allowed us to carry out liver resection on patients with advanced HCC.     

A 0.18-μm 256-Mb DDR-SDRAM with low-cost post-mold tuning methodfor DLL replica

A 200-MHz double-data-rate synchronous-DRAM (DDR-SDRAM) was developed. The chip contains a delay-locked loop (DLL) which performs over a wide range of operating conditions. Post-mold-tuning allows precise replica programming. A 200-MHz intra-chip data bus is suitable for DDR operation     

Axial plastic collapse behavior of plates

In the present study, the collapse behavior of a plate subjected to axial compression is investigated parametrically using the finite element method. It is shown that the axial collapse of the plate, which has various hardening characteristics, is controlled by two dominant factors: the stress limitation of the material and the limitation of in-plane lateral deformation at the side edges of the plate. Then, a simplified collapse condition, which corresponds to two collapse types, is derived based on the effective width concept and the plastic theory, and the validity of the collapse condition is then verified by the comparison of numerical results obtained under various material and geometric properties. Furthermore, a method for predicting the collapse stress is proposed based on the present collapse condition.