Signature of room temperature ferromagnetism in Mn doped CeO2 nanoparticles

We report structural and magnetic properties of Mn doped CeO₂ nanoparticles using X-ray diffraction (XRD), field emission transmission electron microscopy (FE-TEM) and dc magnetization measurements. XRD results infer that all the samples have single phase nature and lattice parameters decrease with Mn doping. The particle size calculated using XRD and TEM analysis was found to decrease with Mn doping. Field cooled magnetization measurement shows that the transition temperature is above room temperature. Magnetic hysteresis loop studies indicate that undoped and Mn doped CeO₂ nanoparticles show weak ferromagnetic behavior at room temperature.     

Effect of intermittent warm blood cardioplegia on functional recovery after prolonged cardiac arrest

BACKGROUND: There is some evidence that continuous warm blood cardioplegia offers good myocardial protection; however, the effects of interrupting cardioplegia remain controversial. To study this, we compared the effects of continuous and intermittent antegrade warm (37 degrees C) blood cardioplegia on functional recovery after prolonged cardiac arrest (180 minutes). METHODS: Twenty-four juvenile pigs were randomly assigned into four groups. Group 1 received continuous cardioplegia, group 2 underwent several periods of 15 minutes of cardioplegia interrupted by 5 minutes of normothermic ischemia, and group 3 underwent several periods of 10 minutes of cardioplegia interrupted by episodes of 10 minutes. The hearts of group 4 received no cardioplegia. Left ventricular systolic function was assessed from fractional left ventricular shortening and percentage left ventricular wall thickening, and left ventricular diastolic function was determined from the time constant of relaxation and the constant of myocardial stiffness. RESULTS: Systolic and diastolic functions were slightly depressed 1 and 2 hours after cross-clamp removal in all four groups, without significant differences among the groups. CONCLUSIONS: These data suggest that antegrade warm blood cardioplegia can be interrupted for up to 10 minutes without obvious negative effects on left ventricular function in the normal myocardium, provided that the intermittent doses of cardioplegia are sufficient to restore the metabolic demands of the arrested myocardium.     

Nanostructured phenolic matrices: Effect of different nanofillers on the thermal degradation properties and reaction to fire of a resol

In this work, the effect of 6 different fillers as a nanomodifier of phenolic matrix was evaluated in thermal stability and reaction to fire. The chosen nanoparticles were montmorillonite, silica, carbon black, and 3 carbides—boron, silicon, and zirconium carbides. The nanofillers were mechanically dispersed in the matrix, and the dispersion and distribution of the nanosized particles in the matrix was evaluated by transmission electron microscopy. The thermal stability of nanocomposites was investigated by thermogravimetric analysis both in nitrogen and in air while the thermal combustion properties were measured using a microscale combustion calorimeter. The experimental data highlighted the remarkable effects of nanoboron carbide on the thermal properties it can confer to the phenolic matrix. Rheological behavior of the blends was also investigated to evaluate the effect of the different fillers on the viscosity of the nanostructured matrices.     

Software design specification and analysis technique (SDSAT) for the development of safety-critical systems based on a programmable logic controller (PLC)

This paper introduces a Software Design Specification and Analysis Technique (SDSAT) for safety-critical systems based on a Programmable Logic Controller (PLC). During software development phases, the design phase performs an important role in connecting the requirements phase and the implementation phase, and it is a process of translating software requirements into software structures. In this work, the Nuclear FBD-style Design Specification and analysis (NuFDS) approach was proposed for nuclear Instrumentation and Control (I&C) software. The NuFDS approach is suggested in a straightforward manner for effective and formal software design specification and analysis. Accordingly, the proposed NuFDS approach is composed of a software design specification technique and a software design analysis technique. In addition, for tool support in the design phase, we developed the NuSDS tool based on the NuFDS approach; this tool is used specifically for generating software design specification and analysis for nuclear fields.     

Development of a cause analysis system for a CPCS trip by using the rule-base deduction method

A Core Protection Calculator System (CPCS) was developed to initiate a Reactor Trip under the circumstance of certain transients by a Combustion Engineering Company. The major function of the Core Protection Calculator System is to generate contact outputs for the Departure from Nucleate Boiling Ratio (DNBR) Trip and a Local Power Density (LPD) Trip. But in a Core Protection Calculator System, a trip cause cannot be identified, thus only trip signals are transferred to the Plant Protection System (PPS) and only the trip status is displayed. It could take a considerable amount of time and effort for a plant operator to analyze the trip causes of a Core Protection Calculator System. So, a Cause Analysis System for a Core Protection Calculator System (CASCPCS) has been developed by using the rule-base deduction method to assist operators in a Nuclear Power Plant. CASCPCS consists of three major parts. Inference engine has a role of controlling the searching knowledge base, executing the rules and tracking the inference process by using the depth-first searching method. Knowledge base consists of four major parts: rules, data base constants, trip buffer variables and causes. And a user interface is implemented by using menu-driven and window display techniques. The advantage of CASCPCS is that it saves time and effort to diagnose the trip causes of a Core Protection Calculator System, it increases a plant’s availability and reliability, and it makes it easy to manage CASCPCS because of using only a cursor control.     

Thin film silver deposition by electroplating for ULSI interconnect applications

Ag seed layers were pretreated with 1: 1,000 diluted nitric acid cleaning solution for 60 s to obtain a clean and oxide-free Ag surface. When an applied potential was less than ?800 mV in Ag electroplating, the deposition rate was over 2,000 Å/min and the resistivity of Ag deposit was 1.80 μΩ·cm. But the deposit film became rougher with a negative increase in the potential, and it was also observed through measuring the double layer capacitance. The resistivity of Ag film annealed at 350 °C for 30 min was decreased from 1.80 μΩ·cm to 1.67 μΩ·cm and the agglomeration of Ag grains was not observed on the surface of the annealed Ag films. To reduce the surface roughness, thiourea was added in the electrolyte and it was decreased below 15 nm.     

Security vulnerability in a non-interactive ID-based proxy re-encryption scheme

Recently, a non-interactive identity-based proxy re-encryption scheme was proposed for achieving CCA-security. In the paper, we show that the identity-based proxy re-encryption scheme is unfortunately vulnerable to a collusion attack. The collusion of a proxy and a malicious user enables two parties to derive other honest user's private key and thereby decrypt ciphertexts intended for the honest user.     

Green's function method with consideration of temperature dependent material properties for fatigue monitoring of nuclear power plants

In this paper, a method to consider temperature dependent material properties when using the Green's function method is proposed by using a numerical weight function approach. This is verified by using detailed finite element analyses for a pressurizer spray nozzle with various assumed thermal transient load cases. From the results, it is found that the temperature dependent material properties can significantly affect the maximum peak stresses and the proposed method can resolve this problem with the weight function approach. Finally, it is concluded that the temperature dependency of the material properties affects the maximum stress ranges for a fatigue evaluation. Therefore, it is necessary to consider this effect to monitor fatigue damage when using a Green's function method for the real operating conditions in a nuclear power plant.     

An experimental study on LMR core seismic behavior with fluid couplings between closely spaced hexagons

In LMR (Liquid Metal Reactor) core seismic behavior, the fluid coupling between closely spaced hexagons is known to have a very strong effect on the natural frequencies and the seismic responses. In this paper, an experimental study is carried out to investigate the fluid coupling effects with reduced scale mock-ups with three types of hexagonal duct systems and three types of input seismic motions such as the ElCentro 1940 time history, the artificial time history (Reg. 1.60), and the Kobe time history by using a one-dimensional shaking table facility. The results of the experimental studies are compared and discussed with those of the analyses performed by using the SAC-CORE code, which implements a numerical algorithm of the CFAM (Consistent Fluid Added Mass) matrix proposed in a previous paper. From the results, it is found that the fluid coupling between closely spaced hexagons becomes stronger with an increasing number of the neighboring hexagonal ducts, and this causes the natural frequency to be significantly changed and it affects the seismic time history responses too.     

Torque control strategy for a parallel-hybrid vehicle using fuzzy logic

In this article, we introduce a fuzzy logic controller to the driving strategy of a hybrid electric vehicle (HEV). The decision making of this fuzzy logic controller is useful to nonlinear and uncertain systems such as electric vehicle applications, and the fuzzy logic controller is immune to various vehicle load and road conditions. To construct the proper rule base of the fuzzy logic controller, the torque-producing, pollutant-emission, and fuel-consumption characteristics of the diesel engine and the hybrid system are clarified through dynamo testing. Then, the driving patterns of the driver and vehicle load on the service course are investigated. These results are also reflected in constructing the rule bases of the proposed fuzzy logic controller. To prove the usefulness of the proposed fuzzy logic controller, actual road tests of the parallel HEV are carried out. Note that the battery maintains its nominal voltage through 20 days of running without extra charging process.