Search

In order to analyze the inter-harmonic affections on the voltage flicker, the relationship between the inter-harmonics and flicker analysis are carried out. In order to be able to accurately determine the level of inter-harmonics to make the electric light flicker, inter-harmonic-flicker limit curve drawing method based on the voltage flicker constraints is established. Analog tester flicker and inter-harmonic-flicker experimental platform are built; limit curve can be drawn through the experimental data. The 2 kinds of harmonic-flicker limit curves for the 220 V, 50 Hz fluorescent lamp are drawn by the 2 methods separately, and the analysis results show that the accuracy of the results obtained by the two methods, the level of inter-harmonics whether lead to fluorescent flicker can be determined by the curves. The methods have the small amount of calculation, and are practical and easy to implement.

Hadoop is a distributed computing system widely used for big data processing in various domains. As the data volume continues to increase rapidly, Hadoop systems have become a critical contributor to the success of many big data applications. The MapReduce scheduler is a key component that determines the overall performance of a Hadoop cluster. In this paper, we formulate and investigate a task scheduling problem in a heterogeneous Hadoop cluster to minimize the completion time of a batch of MapReduce jobs. We first design a prediction model to predict the end time of a task, which is used for placing the corresponding data block on a node in advance to reduce the data transmission time and the overall job completion time. Based on this prediction model, we propose a task matching-based scheduling algorithm, referred to as TMSA, to schedule the tasks in the task queue in Hadoop, by taking into account the real-time performance of each node in the cluster and the matching degree between nodes and tasks. Experimental results show that the prediction model achieves high accuracy and TMSA significantly reduces the completion time of a batch of MapReduce jobs compared to existing schedulers.

Multi-path routing has been increasingly used to improve aggregate bandwidth for big data transfer in various network environments. Typical solutions to this problem include a path set with the largest total bandwidth and the widest path pair. In this paper, we formulate a multi-path routing problem to maximize the total bandwidth of k edge-disjoint paths, where k > 1. We show this problem to be NP-complete and propose a heuristic algorithm with focus on global optimization. We implement the proposed algorithm and evaluate its performance in comparison with existing solutions in the literature. Extensive simulation results illustrate the superiority of the proposed algorithm in terms of aggregate bandwidth and satisfaction of edge count constraint.

With the rapid deployment of cloud infrastructures around the globe and the economic benefit of cloud-based computing and storage services, an increasing number of scientific workflows have been shifted or are in active transition to clouds. As the scale of scientific applications continues to grow, it is now common to deploy data- and network-intensive computing workflows across multi-clouds, where inter-cloud data transfer has a significant impact on both workflow performance and financial cost. We construct rigorous mathematical models to analyze intra- and inter-cloud execution dynamics of scientific workflows and formulate a budget-constrained workflow mapping problem to optimize the network performance of MapReduce-based scientific workflows in Hadoop systems in multi-cloud environments. We show this problem to be NP-complete and design a heuristic solution that takes into consideration module execution, data transfer, and I/O operations. The performance superiority of the proposed mapping solution over existing methods is illustrated through extensive simulations and further verified by real-life workflow experiments deployed in public clouds. We observe about 15% discrepancy between our theoretical estimates and real-world experimental measurements, which validates the correctness of our cost models and also ensures accurate workflow mapping in real systems.

MicroRNA-148a (miR-148a) has been reported to be deregulated in different tumor types, whereas the biological function of miR-148a in renal cell carcinoma (RCC) largely remains unexplored. In the present study we investigated the clinical significance, biological effects, and the underlying molecular mechanisms of miR-148 in RCC. Here, we showed that miR-148a was significantly downregulated in RCC tissues and cell lines. Low expression of miR-148a in RCC tissues was associated with large tumor size, advanced TNM stage, and lymph node metastasis. Functional assays revealed that overexpression of miR-148a significantly inhibited RCC cell proliferation, colony formation, migration and invasion in vitro and suppressed RCC xenograft tumor growth in vivo. In addition, using quantitative RT-PCR (qRT-PCR), western blot analysis and luciferase reporter assays, AKT2 was confirmed to be a direct target of miR-148a. AKT2 expression was upregulated, and was negatively correlated with miR-148a expression in RCC tissues (r=-0.641, P

As a special commodity, electricity has the characteristics of the being produced and used at the same time and it is not physical visible. In order to avoid the loss in circulation of electricity, we should have a thorough understanding and accurate recognition of "power". The watt-hour meter measuring power depends on the product of voltage, current, power factor and the time. Changing any of these elements will have an impact on the measurement of electrical energy which will cause the measuring error of electrical energy and also cause the economic loss to power supply enterprise. Through the description of the working principle of the watt-hour meter, this thesis expounds the current and the current changes can impact to electrical energy measurement.

In order to analyze the inter-harmonic affections on the voltage flicker, the relationship between the inter-harmonics and flicker analysis are carried out. In order to be able to accurately determine the level of inter-harmonics to make the electric light flicker, inter-harmonic-flicker limit curve drawing method based on the voltage flicker constraints is established. Analog tester flicker and inter-harmonic-flicker experimental platform are built; limit curve can be drawn through the experimental data. The 2 kinds of harmonic-flicker limit curves for the 220 V, 50 Hz fluorescent lamp are drawn by the 2 methods separately, and the analysis results show that the accuracy of the results obtained by the two methods, the level of inter-harmonics whether lead to fluorescent flicker can be determined by the curves. The methods have the small amount of calculation, and are practical and easy to implement.

In the electric energy metering device, due to errors of a current transformer or a voltage transformer phase sequence and polarity, wiring false often happens in the electric energy metering device. It affects the accuracy of electric energy metering device and results in inaccurate metering. For this reason, it is necessary to analyze, check and calculate correction coefficients of the error electric quantity, after that you can obtain electric charge refund correctly. This paper lists several common false wiring and inspection methods of three-phase and three-wire electric energy meter. Through the analysis of the vector, it can deduce active power expression of the electric energy meter false wiring, calculate correction coefficient, and confirm electric charge refund.

Through several examples, describes the harmonic distribution network and its equipment hazards. Harmonics can cause distribution transformers demonstration power loss and additional loss increases, resulting in reduced aging transformer oil and insulation properties, triggering a distribution transformer discharge breakdown or burn accidents; harmonics is amplified in a capacitor bank, and cause the capacitor bank fuse group burst, tripping and other accidents; harmonics cause the motor to reverse, vibration, noise and temperature; harmonic electromagnetic voltage transformer prone to occur ferromagnetic resonance over-voltage; harmonics resulting in increased distribution network line losses. Awareness and understanding harmonics, harmonic provide for effective governance scientific theory. Introduction Nonlinear load and impact load when produce can produce harmonics, and the distribution of injection, if is the injection of harmonic frequency (50 Hz) 2, 3, 5, 7 times the size of an integer, is the high frequency[1-3]. If the injection of harmonic frequency (50 Hz) 1/2, 1/3, several times, 2/3, 2/5, 1/5 is the frequency division; Harmonic pollution to the power system is not allow to ignore, because electric furnace, electric arc furnace, electrolytic furnace, intermediate frequency furnace and other commonly used straight in 10 kV power distribution net, so the nonlinear load and as the direct input to the distribution of harmonic sources, will cause the current, voltage waveform distortion, distribution network harmonic generation. Harmonic produces serious pollution to power network, and even equipment in distribution network transformer, capacitor Banks, motor, voltage transformer, such as destructive, and lead to distribution network line loss increase[4, 5]. Figure 1 The 10kV substation system wiring diagram Harmonic harm to distribution transformer (1)Accident cases Figure 1 is for a 10 kV substation system wiring diagram, Oriental carbon factory main production machinery: crusher, milling machine, calcinations furnace, vibrating screen, press