Effect of Ni loading and calcination temperature on catalyst performance and catalyst deactivation of Ni/SiO2 in the hydrodechlorination of 1,2‐dichloropropane into propylene

The hydrodechlorination of 1,2‐dichloropropane (DCPA), a chlorinated organic waste which is produced in the epichlorohydrin process, to propylene was carried out over Ni/SiO₂ catalysts. The effects of Ni loading and calcination temperature on catalyst performance and catalyst deactivation of Ni/SiO₂ were systematically investigated. The Ni/SiO₂ catalysts efficiently converted DCPA into propylene in 95% selectivity or higher. The particle size of Ni on SiO₂ was strongly related to the catalyst stability. In terms of the effect of Ni loading, the largest Ni particles on SiO₂ showed the best durability against deactivation. A series of TPR and UV‐DRS measurements revealed that nickel hydrosilicate was formed as the result of the interaction between Ni and SiO₂. Nickel hydrosilicate was found to be responsible for the catalyst stability leading to low catalyst deactivation. HCl adsorption on Ni/SiO₂ was the main reason for catalyst deactivation. HCl modified the crystal structure of metallic Ni to NiCl₂ and led to irreversible deactivation and metal sintering. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of temperature and strain range on fatigue cracking behavior in Hastelloy X

The low cycle fatigue tests of Ni-base superalloy Hastelloy X have been carried out in the temperature range of 650 - 870 °C with various total strain ranges. A change of slope in the Coffin-Manson (C-M) plot was found at 870 °C: the fatigue life significantly decreased at the total strain range less than 0.6%. The fatigue cracks initiated at the surface of the specimens and propagated transgranularly, regardless of test condition. However, the fatigue crack initiation site on the surface shifted from grain interior to grain boundary (GB) predominantly when the discontinuity of slope in the C-M plot began to occur. The fatigue crack tended to initiate preferentially at the oxidized GB rather than grain interior at 870 °C with total strain range below 0.6%. Under this condition, cyclic stability was pronounced, while cyclic hardening occurred at the rest of test conditions. The dislocation structures responsible for the cyclic stress response may partly account for the determination of major fatigue crack initiation site.     

Low-velocity impact analysis of composite laminates under initial in-plane load

In this paper, low-velocity impact response and damage of composite laminates is analytically investigated. A modified displacement field of the plate considering initially loaded in-plane strain is proposed. From the displacement field, a finite element equation on the structural behavior of composite laminate is newly induced and a computational program is coded. Numerical results using the FEM code is compared with the numerical ones from reference. Additional numerical analysis is performed on another impact condition, and the effect of initial in-plane load is investigated. Potential delamination damage area in the first inter-ply surface from the bottom of the laminate is approximately estimated, and the effect of the initial in-plane load and the impact condition are also investigated. Consequently, it may be concluded that the initial in-plane load of the laminate does not affect so much on the impact damage area of the laminate.     

Modeling of target detection in local search for phased array radar tracking

The local search in tracking with a phased array radar can be characterized in terms of the events that can occur in the search and the probabilities of those events. In predicting the event probabilities, it is required to evaluate the expectation of a product of target detection probabilities for repeated beam-positioning in the local search. In this paper, we present a model of the local search and derive an expression for the expectation of the detection-probability product. An expression of angular measurement accuracy of target detection is also presented. Evaluation of the expressions requires numerical integration, which is computationally expensive. Approximations to the expressions are presented in analytic form, which are fairly accurate.     

Canted anisotropy magnetoelastic resonance material as sensors for electronic article surveillance system

A self-biasing magnetostrictive element for a magnetomechanical Electronic Article Surveillance (EAS) marker is fabricated by annealing a ribbon of ferromagnetic amorphous material (Co_47.4Fe_31.6Si₂Bi₁₉) in a presence of magnetic field applied in a transverse direction relative to the ribbon’s longitudinal axis, and then annealing in a presence of magnetic field applied in the direction of the longitudinal axis. The two-step annealed ribbon exhibits remanent magnetization along the longitudinal axis and has plural magnetic domains situated along the longitudinal axis. The magnetic orientation of each domain is canted by ± 03B8; < 90° from the ribbon axis with the direction of canting alternating from domain to domain. To obtain such a canted anisotropy, theoretical background for the calculation of the field strength (H) and canted angle (θ) is described.     

Driving force for γ→ε martensitic transformation and stacking fault energy of γ in Fe-Mn binary system

A regular solution model for the difference of the chemical free energy between γ and ε phases during γ→ε martensitic transformation in the Fe-Mn binary system has been reexamined and partly modified based on many articles concerning the M _s and A _s temperatures of Fe-Mn alloys. Using the regular solution model, the measured M _s temperatures, and a thermodynamic model for the stacking fault energy (SFE) of austenite (γ), the driving force for γ→ε martensitic transformation, and the SFE of γ have been calculated. The driving force for γ→ε martensitic transformation increases linearly from − 68 to − 120 J/mole with increasing Mn content from 16 to 24 wt pct. The SFE of γ decreases to approximately 13 at. pct Mn and then increases with increasing Mn content, which is in better agreement with Schumann’s result rather than Volosevich et al.’s result.     

Process capability indices for skewed populations

This paper proposes a new method of constructing process capability indices (PCIs) for skewed populations. It is based on a weighted standard deviation method which decomposes the standard deviation of a quality characteristic into upper and lower deviations and adjusts the value of the PCI using decomposed deviations in accordance with the skewness estimated from sample data. For symmetric populations, the proposed PCIs reduce to standard PCIs. The performance of the proposed PCIs is compared with those of standard and other PCIs, and finite sample properties of the estimates are investigated using Monte Carlo simulation. Numerical studies indicate that considerable improvements over existing methods can be achieved by the use of the weighted standard deviation method when the underlying distribution is skewed. Copyright © 2002 John Wiley & Sons, Ltd.     

Cerebral arteriovenous malformations in children: neuroimaging findings

Cerebral arteriovenous malformations (CAVMs) are uncommon in children. CAVMs represent the most frequent intracranial vascular pathology at pediatric ages. This report concerns 13 children below the age of 16; all were identified between September 1995 and December 1996 with 14 CAVMs among them. All were proved by conventional cerebral angiography (CCA). Thirteen computed tomography (CT), 7 magnetic resonance images (MRI), 2 magnetic resonance angiography (MRA) and 13 conventional cerebral angiography (CCA) were analyzed. Most CAVMs nidus were located in cerebral hemispheres. Four in the temporal lobe, two in the parietal lobe, three in the frontal lobe, two in the occipital lobe, and three in the corpus callosum. One of them was of a mixed type with two nidi. The major clinical features of CAVMs were intracranial hemorrhage and seizures. Experience here was that MRI is superior to CT in showing the exact anatomic relationships of the nidus and in demonstrating the extent of CAVMs nidus obliteration after treatment. MRA provided a noninvasive means of studying blood vessels and vascular pathology in relationship to the CAVMs nidus. Standard angiography is still necessary to characterize in-flow and out-flow of vessels in CAVMs when definitive treatment is considered.     

Intake of fatty acids and risk of coronary heart disease in a cohort of Finnish men. The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study

The relation of intakes of specific fatty acids and the risk of coronary heart disease was examined in a cohort of 21,930 smoking men aged 50-69 years who were initially free of diagnosed cardiovascular disease. All men participated in the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study and completed a detailed and validated dietary questionnaire at baseline. After 6.1 years of follow-up from 1985-1988, the authors documented 1,399 major coronary events and 635 coronary deaths. After controlling for age, supplement group, several coronary risk factors, total energy, and fiber intake, the authors observed a significant positive association between the intake of trans-fatty acids and the risk of coronary death. For men in the top quintile of trans-fatty acid intake (median = 6.2 g/day), the multivariate relative risk of coronary death was 1.39 (95% confidence interval (CI) 1.09-1.78) (p for trend = 0.004) as compared with men in the lowest quintile of intake (median = 1.3 g/day). The intake of omega-3 fatty acids from fish was also directly related to the risk of coronary death in the multivariate model adjusting also for trans-saturated and cis-monounsaturated fatty acids (relative risk (RR) = 1.30, 95% CI 1.01-1.67) (p for trend = 0.06 for men in the highest quintile of intake compared with the lowest). There was no association between intakes of saturated or cis-monounsaturated fatty acids, linoleic or linolenic acid, or dietary cholesterol and the risk of coronary deaths. All the associations were similar but somewhat weaker for all major coronary events.     

EMG pattern classification using SOFMs for hand signal recognition

 We propose a method of pattern classification of electromyographic (EMG) signals using a set of self- organizing feature maps (SOFMs). The proposed method is simple to apply in that the EMG signals are directly input to the SOFMs without preprocessing. Experimental results are presented that show the effectiveness of the SOFM based classifier for the recognition of the hand signal version of the Korean alphabet from EMG signal patterns.