Copper activated LiF nanorods as TLD material for high exposures of gamma-rays

Lithium fluoride (LiF) doped with proper activators is a highly sensitive phosphor commonly used for radiation dosimetry using thermoluminescence (TL) technique. Nanorods of this material activated with Cu, Mg and P as single dopants are synthesized in our laboratory and exposed to gamma-rays for their thermoluminescence (TL) properties. The induced TL glow curves of the Cu, Mg and P doped samples are similar with a single peak at 410 K. Copper doped sample is found to be the most sensitive sample with TL intensity around 65, 7 and 8 times of those of LiF:Mg, LiF:P and LiF:Mg,Cu,P, respectively, indicating that Cu is the luminescence center in the host of LiF nanorods, while Mg and P act as TL quencher particularly when used as codopants. These observations on the nanostructured form of LiF doped with these activators are entirely different from those of the widely studied LiF:Mg,Cu,P and LiF:Mg,Ti single crystals. The nanorods of LiF:Cu might be used for heavy doses measurement as they are sensitive to gamma-rays and have a linear TL response curve in a long span of exposures.     

广域保护中基于能量守恒原理的母线及输电线差动保护

提出一种基于能量守恒原理的纵联差动保护,对线路两端或母线各端的有功功率进行比较,若各端功率的和超出整定值,则判定为区内故障。在典型400 kV输电系统模型上,运用MATLAB仿真软件对所提出的原理进行了仿真验证。仿真结果表明,该方法比传统电流比率差动保护更加可靠且计算量小,因而可缩短动作时间。该方法能检测所有故障类型,适应于超高压远距离输电线路。     

Effect of an electric field on the transport of Th(IV) in the presence of Eu(III) and U(VI) through supported liquid membrane containing di‐2‐ethylhexylphosphoric acid

This paper investigates the transport of Th(IV) ions in nitric acid media through a supported liquid membrane (SLM) impregnated with di‐2‐ethylhexylphosphoric acid (HDEHP) in kerosene using an electric field. The transport was carried out in a three compartment cell fitted with microporous cellulose nitrate (SLM) and cation exchange membrane (Nafion). The effect of different parameters including nitric acid concentration in the feed solution, HDEHP concentration in the membrane, and HCl concentration were studied. The optimal conditions for Th(IV) transport were 0.1 mol dm^?3 HDEHP, 10^?3 mol dm^?3 HNO₃ in the feed solution, 1 mol dm^?3 HCl in compartment 2 and 1 mol dm^?3 HCl in compartment 3 at 25 °C. Under the optimal conditions of Th(IV) transport the recovery factor after 90 min was 0.25 without applying an electrostatic field, compared with 0.9 when the electric field was applied. The effect of electric current on the flux of Th(IV) through the membrane was also studied. The flux increased as the current density increased from 10 to 30 mA cm^?2 to reach a maximum value at 30 mA cm^?2 (8 × 10^?9 g eq cm^?2 s^?1). The transport percentages of 0.3 g dm^?3 Th(IV) in the presence of 0.1 g dm^?3 Eu(III) and 1 g dm^?3 U(VI) were 66, 84 and 15%, respectively. The determined selectivities of U(VI)–Th(IV) and Th(IV)–Eu(III) were 0.12 and 0.3, respectively, after 90 min. Therefore, the order of selectivity of this system is Eu(III) > Th(IV) > U(VI). © 2001 Society of Chemical Industry     

Disaster-survivable cloud-network mapping

Cloud-computing services are provided to consumers through a network of servers and network equipment. Cloud-network (CN) providers virtualize resources [e.g., virtual machine (VM) and virtual network (VN)] for efficient and secure resource allocation. Disasters are one of the worst threats for CNs as they can cause massive disruptions and CN disconnection. A disaster may also induce post-disaster correlated, cascading failures which can disconnect more CNs. Survivable virtual-network embedding (SVNE) approaches have been studied to protect VNs against single physical-link/-node and dual physical-link failures in communication infrastructure, but massive disruptions due to a disaster and their consequences can make SVNE approaches insufficient to guarantee cloud-computing survivability. In this work, we study the problem of survivable CN mapping from disaster. We consider risk assessment, VM backup location, and post-disaster survivability to reduce the risk of failure and probability of CN disconnection and the penalty paid by operators due to loss of capacity. We formulate the proposed approach as an integer linear program and study two scenarios: a natural disaster, e.g., earthquake and a human-made disaster, e.g., weapons-of-mass-destruction attack. Our illustrative examples show that our approach reduces the risk of CN disconnection and penalty up to 90 % compared with a baseline CN mapping approach and increases the CN survivability up to 100 % in both scenarios.     

Characterization of the continuous-flow mixing of non-Newtonian fluids using the ratio of residence time to batch mixing time

Continuous-flow mixing of pseudoplastic fluids possessing yield stress is a complex phenomenon exhibiting non-ideal flows within the stirred vessels. Electrical resistance tomography (ERT), a non-intrusive technique, was employed to measure the mixing time in the batch mode while dynamic tests were performed to study the mixing system in the continuous mode. This study attempts to explore the effects of the operating conditions and design parameters on the ratio of the residence time (τ) to the mixing time (θ) for the continuous-flow mixing of non-Newtonian fluids. To achieve these objectives, the effects of impeller types (four axial-flow impellers: A310, A315, 3AH, and 3AM; and three radial-flow impellers: RSB, RT, and Scaba), impeller speed (290–754 rpm), fluid rheology (0.5–1.5%, w/v), impeller off-bottom clearance (H/2.7–H/2.1, where H is the fluid height in the vessel), locations of inlet and outlet (configurations: top inlet-bottom outlet and bottom inlet-top outlet), pumping directions of an axial-flow impeller (up-pumping and down-pumping), fluid height in the vessel (T/1.06–T/0.83, where T is the tank diameter), residence time (257–328 s), and jet velocity (0.317–1.66 ms⁻¹) on the ratio of τ to θ were investigated. The results showed that the extent of the non-ideal flows (channeling and dead volume) in the continuous-flow mixing approached zero when the value of τ/θ varied from 8.2 to 24.5 depending on the operating conditions and design parameters. Thus, to design an efficient continuous-flow mixing system for non-Newtonian fluids, the ratio of the residence time to the mixing time should be at least 8.2 or higher.     

SPARCL: an effective and efficient algorithm for mining arbitrary shape-based clusters

Clustering is one of the fundamental data mining tasks. Many different clustering paradigms have been developed over the years, which include partitional, hierarchical, mixture model based, density-based, spectral, subspace, and so on. The focus of this paper is on full-dimensional, arbitrary shaped clusters. Existing methods for this problem suffer either in terms of the memory or time complexity (quadratic or even cubic). This shortcoming has restricted these algorithms to datasets of moderate sizes. In this paper we propose SPARCL, a simple and scalable algorithm for finding clusters with arbitrary shapes and sizes, and it has linear space and time complexity. SPARCL consists of two stages—the first stage runs a carefully initialized version of the Kmeans algorithm to generate many small seed clusters. The second stage iteratively merges the generated clusters to obtain the final shape-based clusters. Experiments were conducted on a variety of datasets to highlight the effectiveness, efficiency, and scalability of our approach. On the large datasets SPARCL is an order of magnitude faster than the best existing approaches.     

ISM analysis of CPFR implementation barriers

Collaborative planning, forecasting and replenishment (CPFR) as an interconnection scheme between organisations have been shown to have significant benefits. Since its inception in the 1990s, its uptake has been lower than originally predicted. This paper identifies the major barriers and their interrelationships in CPFR implementations with a focus on high-tech industries. Interpretive Structural Modelling is used with a group of CPFR experts from industry/academia and Matrice d’Impacts Croisés Multiplication Appliquée àun Classement analysis to identify the driving and dependence powers. The paper identified 45 CPFR barriers and classifies them into four categories based on expert opinion, with only 13 of these determined to be significant. The results indicate that in terms of categories, managerial barriers are a significant root cause for both process and cultural barriers and CPFR implementation difficulties. It also indicates that although the importance of information technology to launch collaborative schemes has been addressed by many scholars, technology alone is not the complete solution for successful CPFR implementation. The paper has significant practical implications for organisations as it identifies the main CPFR barriers and their causal relationships. This will help firms in the process of CPFR strategy development particularly for mitigation strategies for dominant barriers.     

Design of RF MEMS Based Oscillatory Neural Network for Ultra High Speed Associative Memories

Microelectromechanical systems are utilized alongside with transistor amplifiers and resistive connections for implementing of oscillatory associative memories. Phase locking is studied in such a network and all requirements of the circuit level implementation are satisfied. A very high gain trans-impedance amplifier operating in 1 GHz in addition to a novel automatic amplitude control circuit is employed to remove amplitude dynamics of the system. Requiring resonator characteristics are extracted and calculated as well. A new method for initialization of the network is proposed. Each neuron consumes 1.08 mW from a 1.8 V power supply. The convergence time of a typical network trained by Hebbian rule is less than 1.5 ns which results in an ultra high speed analog signal processing system.     

Heart rate variability in low birth weight growth restricted children during sleep and wake stages

Intrauterine growth restricted (IUGR) individuals have greater predisposition to develop a metabolic syndrome in later life manifesting itself as obesity, hypertension, type 2 diabetes or cardiovascular disease. Poor fetal growth may alter the regularity mechanism of cardiac autonomic system that is involved in the development of these diseases. The malfunctioning of the cardiac autonomic system assessed by decrease in heart rate variability (HRV) is associated with negative cardiovascular outcomes. This study is aimed at investigating the risk of development of coronary heart disease in IUGR children in later life. For that purpose HRV analysis of normal and growth restricted children was performed during sleep and wake stages. The study group consisted of 9–10 years old, 32 normal, 20 low birth weight IUGR children. The standard time domain HRV metrics (mean RR, SDNN, RMSSD, NN50 and pNN50) and Poincaré indices (SD₁ and SD₂) were used to analyse and compare the RR-interval time series of these groups. The IUGR children showed lower HRV as compared with normal children during both sleep and wake stages. The significantly decreased HRV during sleep provide an evidence of autonomic derangement that may be associated with higher risk of lethal arrhythmias in the IUGR children in later life.