SAMES: deadline-constraint scheduling in MapReduce

MapReduce is a popular parallel data-processing system, and task scheduling is one of the kernel techniques in MapReduce. In many applications, users have requirements that their MapReduce jobs should be completed before specific deadlines. Hence, in this paper, a novel scheduling algorithm based on the most effective sequence (SAMES) is proposed for deadline-constraint jobs in MapReduce. First, according to the characteristics of MapReduce, we propose a novel sequence-based execution strategy for MapReduce jobs and a new concept, the effective sequence (ES). Then, we design some efficient approaches for finding ESes and choose the most effective sequence (MES) for job execution. We also propose methods for MES-updates and exception handling. Finally, we verify the effectiveness of SAMES through experiments. The experimental results show that SAMES is an efficient scheduling algorithm for deadline-constraint jobs in MapReduce.     

A quantitative investigation of the uncertainty associated with mapping scale in the production of land-cover/land-use data

ABSTRACT

Mapping scale is an essential issue in land use and land cover (LULC) data production, which always involves the minimum mapping unit (MMU) that stipulated in the product specification. Since the application of MMUs will inevitably cause some inappropriate classification problems, a technique is needed to evaluate the impact on the data outputs. In this study, a novel method is proposed to investigate the classification uncertainty brought by MMUs on LULC data. The omission errors are predicted based on an assumption of the skewed frequency distribution of the LULC patch size, and the commission errors are subsequently computed through the conversion possibilities among different land classes, which can be deduced from the generalization rule. A test is conducted on real data to verify the underlying assumption on the patch size distribution, and the accuracy of the prediction of omission errors is evaluated through a simulation experiment. A case study is also presented to demonstrate the efficiency and feasibility of the proposed method. At the end of this article, the advantages and notes of this method are discussed for further study and application.     

高速公路路灯系统无功倒送电网的影响分析

部分用户存在因某些时段功率因数过低,引发无功功率倒送电网的情况,会给电网运行和用户自身带来不利的影响。以某高速公路路灯线路的无功功率倒送电网作为案例,分析了问题产生的原因,提出了解决方法。     

涩北气田多层疏松砂岩储层动态描述

阐述了储层动态描述技术原理。结合气井生产与不稳定测试资料对涩北气田进行了储层动态分析，研究了储层动态模型，确定了地层参数，指出涩北气田主要存在均质地层、径向复合地层与多层窜流三种地层模型，认为径向复合地层与多层窜流地层均是气井多层合采的动态反映。为了研究储层动态模型随时间的变化，将储层动态描述技术应用于单井多次测试。分析得到，在长期的生产过程中，气藏的地层模型、储层参数并没有发生明显变化。储层动态描述确定的地层模型在产能计算与产能预测、气井生产预测等方面有着重要的作用，比静态地质模型更具实际意义。     

Characterization of the deterioration of externally bonded CFRP-concrete composites using quantitative infrared thermography

Defects embedded in externally-bonded CFRP-concrete composite structures reduce the interfacial bond strength and durability. This paper classifies these defects into two types: flaws and delaminations. Flaws are formed during the first application of the CFRP strips onto the concrete surface due to poor workmanship. Delaminations are formed due to stress concentrations related to chemical/physical degradation of the binding layer. In this study, an aggressive environment was simulated by placing the specimens in water baths with elevated temperatures (40 °C and 60 °C). The sizes of the CFRP-flaws and delaminations were determined by (i) quantitative infrared thermography (QIRT) and (ii) processing of visual images after opening-up the CFRP by direct shear. Experimental results show that apparent flaw sizes determined by QIRT were in good agreement (88% accuracy) with actual flaw sizes determined by the image processing method. The results also show that flaws exhibited little change but the bonding layer showed significant deterioration after exposure to high water temperatures.     

Adsorption and desorption behaviour of Pb(II) on a natural kaolin: equilibrium,kinetic and thermodynamic studies

BACKGROUND: Pb(II) is common in both waste‐waters and gas emissions. In developing countries, public health problems have been reported concerning Pb(II) pollution, so that stringent measures are required to deal with it. MAJOR RESULTS: The adsorption and desorption behaviour of Pb(II) has been investigated on a natural Chinese kaolin. Several factors, including initial concentration, pH, equilibration time, dosage and temperature correlated positively with Pb(II) adsorption. The Pb(II) adsorption capacity of natural kaolin was 165.117 mg g^?1. A kinetic study shows that Pb(II) adsorption on purified kaolin equilibrates within 35 min. The enthalpy changes of Pb(II) adsorption on purified kaolin were 63.683, 20.488 and 21.371 kJ mol^?1 with entropy changes 262.250, 112.210 and 105.120 J mol^?1 K^?1 for solutions containing 50, 100 and 200 mg L^?1 Pb(II) respectively, indicating an endothermic and spontaneous adsorption process. The desorption of Pb(II) from kaolin was difficult with more than 85% Pb(II) removal. Based on X‐ray diffraction (XRD) analysis, the Pb(II) adsorption on natural and purified kaolin was attributed mainly to the magnesite component and complexation with the mineral surface. CONCLUSIONS: Natural kaolin exhibits a satisfactory performance for adsorption of Pb(II) from aqueous solution. The optimum conditions for adsorption were: ionic strength = 0.01 mol L^?1; pH ≥ 7.2; dosage = 10 g L^?1; temperature = 25 °C; duration ≥ 16 h (C_i = 80 mg L^?1); and the optimum conditions for desorption were ionic strength = 0.1 mol L^?1 and pH ≤ 5.0. Copyright © 2009 Society of Chemical Industry     

Efficient ID-based registration protocol featured with user anonymity in mobile IP networks

A secure and efficient ID-based registration protocol with user anonymity is proposed in this paper for IP-based mobile networks. The protocol minimizes the registration delay through a minimal usage of the identity (ID)-based signature scheme that eliminates expensive pairing operations. User anonymity is achieved via a temporary identity (TID) transmitted by a mobile user, instead of its true identity. Additional replay protection from a Foreign Agent (FA) is included in the registration messages to prevent a possible replay attack. A formal correctness proof of the protocol using Protocol Composition Logic (PCL) is presented. Numerical analysis and computer simulation results demonstrate that the proposed protocol outperforms the existing ones in terms of the registration delay, the registration signaling traffic, and the computational load on a Mobile Node (MN) while improving security. For example, the proposed protocol reduces the registration delay up to 49.3 percent approximately, comparing to Yang?s protocol.     

Laminar fully developed forced-convection flow within an asymmetrically heated horizontal double-passage channel

The present analytical study is concerned with the thermal characteristics of hydrodynamically and thermally fully developed flow in an asymmetrically heated horizontal channel, which is divided into two passages (by means of a baffe) for two separate flow streams. Each stream will have its own pressure gradient and hence its own individual velocity profile. Based upon bulk mean temperature of the whole flow in the channel, Nusselt numbers and the generalized temperature profiles in the fully developed regions are determined by means of integration of the momentum and energy equations. Three possible combinations of the thermal boundary conditions on the two wall plates of the channel are considered: isothermal-isothermal, isothermal-isoflux, and isoflux-isoflux. Results show that the thermal characteristics of the fully developed flow could be significantly affected by the position of the baffle, the pressure-gradient ratio by the two separate streams, and thermal boundary conditions on the channel walls.     

Computer simulation of convection in moving arc weld pools

Computer simulation for three-dimensional convection in moving arc weld pools was described, with three distinct driving forces for flow considered — the electromagnetic force, the buoyancy force, and the surface tension gradient on the pool surface. Formulation of the electromagnetic force in the weld pool was presented. The calculated and experimentally observed fusion boundaries were compared. The arc efficiency and spatial distributions of the current density and power density used in the calculations were based on experimentally measured results, in order to verify the model. The effects of the electromagnetic and surface tension forces were discussed.     

基于S3C44BOX＋μcLinux的嵌入式以太网设计

本文介绍了基于一款ARM处理器蜒S3C44BOX的以太网接口电路设计，并详细地阐述了在嵌入式操作系统μcLinux下网卡驱劝的实现。