MOPT: list-based heuristic for scheduling workflows in cloud environment

Cloud computing is a popular and widely adopted computing platform for the execution of scientific workflows as it provides flexible infrastructure and offers access to collection of autonomous heterogeneous resources. Effective scheduling of computationally complex workflows which contain many interconnected tasks is a complex problem and becomes more challenging in cloud environment. Optimal solutions can be obtained by considering not only the heterogeneity of computation costs involved, but also by taking into account the communication costs among the tasks in a way that schedule length of the application is reduced. In this paper, we propose a list scheduling heuristic, namely minimal optimistic processing time (MOPT), with optimized duplication approach. The additional feature is introduced for the entry task and is applied only in scenarios in which duplication is more practical and effective. The prioritization phase of the proposed work is based on an optimistic processing time matrix that is used for ranking of the tasks. The algorithm has same time complexity as state-of-the-art existing algorithms, but notable improvements are acquired in terms of makespan and other performance evaluation parameters. Extensive experimental analysis of the proposed algorithm is carried out using synthesized graphs and graphs from the real-world applications. The results prove that MOPT achieves quality schedules with reduced makespans. As communication cost among the tasks grows higher, performance of the proposed algorithm becomes more effective, thus providing the evidence that the MOPT algorithm is well-suited for communication-intensive applications.

     

An Efficient Rule-Based Distributed Reasoning Framework for Resource-bounded Systems

Mobile Networks and Applications - Over the last few years, context-aware computing has received a growing amount of attention among the researchers in the IoT and ubiquitous computing community....     

LPV Modeling and Tracking Control of Dissimilar Redundant Actuation System for Civil Aircraft

International Journal of Control, Automation and Systems - Dissimilar redundant actuation systems (DRAS) are in practice in advanced aircraft in order to increase reliability and to resolve the...     

Detecting faulty sensors in an array using symmetrical structure and cultural algorithm hybridized with differential evolution

The detection of fully and partially defective sensors in a linear array composed of N sensors is addressed. First, the symmetrical structure of a linear array is proposed. Second, a hybrid technique based on the cultural algorithm with differential evolution is developed. The symmetrical structure has two advantages: (1) Instead of finding all damaged patterns, only (N–1)/2 patterns are needed; (2) We are required to scan the region from 0° to 90° instead of from 0° to 180°. Obviously, the computational complexity can be reduced. Monte Carlo simulations were carried out to validate the performance of the proposed scheme, compared with existing methods in terms of computational time and mean square error.     

Classification of Drinking Water Quality Index and Identification of Significant Factors

Water pipes are considered to be one of responsible sources for the water pollution. Among these sources of water supply, the water pipes are the only source of carrying out fresh or processed water into lakes, ponds and streams etc. In Pakistan, knowledge on the condition of water pipes is scarce as deterioration of water pipes are hardly inspected due to high cost. The aim of the current research was to examine the quality of water pipelines of eight districts of South-Punjab, namely, Mianwali, Khushab, Layyah, Bhakkar, Dera Ghazi Khan, Muzaffargarh, Rajanpur and Rahim Yar Khan. Selected sampling stations were analyzed for physio-chemical parameters such as pH, Total Dissolve Solids (TDS), Sulfate (SO₄), Chlorine (Cl), Calcium (Ca), Magnesium (Mg), Hardness, Nitrate (NO₃), Fluoride (F) and Iron (Fe). The data pertaining water monitoring contain different parameters and seem difficult work for the interpretation of water quality by managing different parameters separately. For this purpose, National Sanitation Foundation Water Quality Index (NSF-WQI) was determined to communicate the quality of water in a simple form. Besides this, groups comprising of similar sampling sites based on water quality characteristics were identified using unsupervised technique. Factor Analysis (FA) has been performed for extracting the latent pollution sources that may cause the more variance in large and complex data. The calculated values of WQI from 1600 sampling stations ranging from 20.73 to 223.74 are divided into five groups; Excellent to Unsuitable class of waters with the average value 62.09 described as good limit for drinking water. Further sampling stations are divided into five optimal clusters selected with suitable k value obtained from Silhouette coefficient. Results of k-means clustering are also verified with natural groups made by WQI. Analysis of multivariate techniques showed several factors to be responsible for the water quality deterioration. It is found out from the FA that three latent factors such as organic pollution, agriculture run-off and urban land use caused 83.30 % of the total variation. Hence, water quality management and control of these latent factors are strongly recommended.     

Fabrication of ceramic micro-scale hollow components by micro-powder injection moulding

Rapid developments in microsystem technologies demand ceramic microcomponents of increasing geometrical complexity. State-of-the-art microfabrication routes of ceramics are either limited in geometrical complexity and/or high volume capabilities. This paper presents a process route by which ceramic microcomponents with relatively complex three-dimensional architectures could be realised by a high-volume technique. The proposed strategy, in which yttria-stabilised zirconia was implemented, combines the capabilities of insert-micromoulding, powder micro-overmoulding, catalytic debinding and sintering. The produced architectures demonstrate the capability of the technique to combine the high performance of ceramic materials with the dimensional accuracy and mass manufacturability of powder micromoulding.     

Molecular and mechanical properties of hydroxypropyl methylcellulose solutions during the sol:gel transition

This paper outlines the latest findings in our work to understand the fundamental interactions within hydrated hydroxypropyl methylcellulose (HPMC) at elevated temperature. ATR-FTIR spectroscopy was used to relate molecular interactions to the rheological changes in aqueous HPMC solutions during the sol:gel transition. Sol:gel transition temperatures determined using ATR-FTIR spectroscopy, oscillatory rheology and turbidimetry were in agreement to within experimental error. ATR-FTIR spectroscopy provided direct evidence of increased hydrophobic interactions within the gel network through a shift to lower wavenumber of ν_as(CH) vibrations observed during the gelation process. In addition, the FTIR spectra provide evidence that the structure of the polymer network is different in the thermo-formed gel, to that which exists in viscous solution. Both the rheological and ATR-FTIR data confirmed the supposition that thermal gelation is a two stage process. The first stage has been attributed to the disruption of native cellulosic bundles and this is supported by the changes in both the storage modulus and intensity of the ν(CO) band at low temperatures. The second stage corresponded to phase separation and gelation resulting from increased hydrophobic interactions between polymer chains at elevated temperatures.     

Energy-efficient dual-port cache architecture with improved performances

Low leakage current and area-efficient dual-port cache design, which uses isolation nodes and local sense amplifiers to facilitate dual-port accesses without duplicating the bit lines for the second port, is presented. Compared with conventional hardwired dual-port cache designs, the average bit line leakage current can be reduced by 50%     

Engineering electrospun nanofibrillar surfaces for spinal cord repair: a discussion

BACKGROUND: The design of implants comprised of biodegradable electrospun nanofibers for the purpose of bridging injuries in damaged spinal cord is discussed. Electrospun nanofibers structurally mimic the extracellular matrix on which neurons and other cell types grow in vivo. This property has created great interest for their use in tissue engineering applications. However, their employment as biomimetic surfaces for such in vivo applications is still in its infancy. RESULTS: A nonwoven fabric comprised of electrospun polyamide nanofibers supported modest axonal regeneration in injured adult rat spinal cord. Covalent modification of the nanofibers with a bioactive peptide derived from the neuroregulatory extracellular matrix molecule tenascin‐C enhanced the ability of the nanofibers to facilitate axonal regrowth. However, the random orientation of the nanofibrillar fabric folds was an impediment to the forward movement of axons. CONCLUSIONS: Polyamide nanofibers covalently modified with neuroactive molecules provide a promising material for grafts to promote spinal cord regeneration. However, for the proper guidance of regrowing axons, attention must be paid to the engineering of ordered nanofibrillar structures. Copyright © 2007 Society of Chemical Industry     

Simulation of a pebble‐bed heat regenerator

A mathematical model to simulate the operational behaviour of a pebble‐bed heat regenerator has been developed, and an experimental study performed to test the model predictions. The model is based on finite heat balances for the solid and the fluid applied to a bed which is divided into several sections insulated from each other. Within each section, there is no radial or axial temperature gradient, i.e. the temperature of all the pebbles in a given section are the same. As the fluid stream flows through the idealized compartmented bed, there is heat exchange in each section between the pebbles and the fluid. The model, which is applicable both to the heating and cooling cycles, has been used to simulate the behaviour of a heat regenerator. To test the predictions of the model, experiments have been performed on a 7 ft by 8 in cylindrical column using a hot air stream of approximately 200°C at an average flow rate of 365 l min^‐1. A special technique, wherein a pebble is fixed to a thermocouple, was used to measure the temperature at different bed positions. Experimental conditions were such that interesting results have been generated. The model was able to predict with good accuracy all the unusual operational behaviour encountered. The deviations between the model and the experimental results can be explained by the fact that the model does not consider heat loss from the column wall. Copyright © 2000 John Wiley & Sons, Ltd.