The purpose of this paper is to introduce a transmission power control scheme based on the remaining energy level and the energy-harvesting status of individual sensor nodes to extend the overall lifetime of wireless sensor networks (WSNs) and balance the energy usage. Ambient energy harvesting has been introduced as a promising technique to solve the energy constraint problem of WSNs. However, considering the tiny equipment and the inherent low and unbalanced harvesting capability due to environmental issues, there is still a long distance from perfectly solving the problem. In this paper, a wind and solar power joint-harvested WSN system has been demonstrated, which uses ultracapacitor as energy storage. By analyzing the power recharging, leakage, and energy consumption rate, a novel energy-level-based transmission power control scheme (EL-TPC) is produced. In EL-TPC scheme, the transmission power is classified into various levels according to the remaining energy level. By adapting the nodes' operation pattern, hierarchical network architecture can be formed, which prioritizes the use of high energy level, fast charging nodes to save the energy of uncharged nodes. The simulation and demonstration results show that EL-TPC scheme can significantly balance the energy consumption and extend the entire network lifetime.
BGP is traditionally configured to implement traffic engineering objectives without considering potential network dynamics. This might result in undesirable traffic distribution when network failures occur. In this paper, we present algorithms for interdomain traffic engineering that achieve the interdomain traffic engineering objectives under network failures. That is, we aim to configure routing policies so that traffic is distributed evenly. More importantly, the configuration is robust in the sense that it is able to achieve the specified traffic engineering goals despite network failures. We first investigate the coarsegrained robust configurations. The derived configuration can achieve optimal robust traffic engineering objectives for most network failures. Further, we develop a greedy algorithm to derive robust BGP configuration for any traffic distribution and link capacities. We use simulations to evaluate the robustness of the derived BGP configurations by applying the algorithm to both transit and stub ASs under realistic traffic demands. Our results show that the derived BGP configurations can improve the default configuration significantly in terms of achieving the robust traffic engineering objectives. Furthermore, our algorithm achieves robust traffic engineering goals without diminishing other routing objectives.
This paper represents the system design and implementation of a wireless power monitoring system for public buildings, which aims to help the country to save energy and electric power supply service providers to determine effective and efficient energy supply in urban area. Public building energy waste has been a big problem in cities and towns in China for several decades. The main reason for this is that people may forget to turn the electrical power off when leaving as the bill is not paid by them. In our monitoring system, a real time electrical power meter is used to track the operation situation, and the sensed data will be sent to the central control device through gateway. The controller will respond to the abnormal usage of electrical power due to this information. The schematic design and working procedure of each component has also been presented in this paper as well.
A coaxial dielectric barrier discharge (DBD) reactor is designed for degradation of aqueous organic pollutant by spraying solution into gaseous discharge plasma. With the intention of finding the most efficient way of energy injection, energy efficiency is studied under experimental conditions with various electrical parameters (applied voltage amplitude, frequency, pulsewidth, pulse shape, and total injection energy) using Rhodamine B as a model. The results show the highest energy performance is achieved at moderate voltage and low frequency with the energy yield G 50 of 41.16 g/kW · h. It is found that at the same energy injection, pulses with a higher amplitude and a lower frequency perform better than those with lower voltage and higher frequency. Pulsewidth does not play an important role in energy efficiency in our DBD reactor. Voltage waveform with a fast falling edge is beneficial to energy efficiency performance.
In order to solve the power angle stability problem of the new power system, this paper proposes an intelligent generation method of the new power system security and stability control strategy based on Q-learning. Firstly, a constrained Markov model of power system stability control problem is established, and the security constraints involved in the emergency control tripping action are summarized and proposed. Secondly, the most typical feature data are selected by feature evaluation and Spearman rank correlation coefficient method. Then, In order to optimize the training effect of the stability control strategy agent., this paper proposes a stability control strategy training framework based on Q-learning algorithm. Finally, this paper tests and verifies in the IEEE-39 node system and an actual power grid. The research results show that the proposed method can automatically adjust and generate the cutting machine stability control strategy according to the running state of the system and the response to the fault, and show better performance in decision-making effect and efficiency.
An all solid-state pulsed power generator for plasma immersion ion implantation (PIII) is described. The pulsed power system is based on a Marx circuit configuration and semiconductor switches, which have many advantages in adjustable repetition frequency, pulse width modulation and long serving life compared with the conventional circuit category, tube-based technologies such as gridded vacuum tubes, thyratrons, pulse forming networks and transformers. The operation of PIII with pulse repetition frequencies up to 500 Hz has been achieved at a pulse voltage amplitude from 2 kV to 60 kV, with an adjustable pulse duration from 1 μs to 100 μs. The proposed system and its performance, as used to drive a plasma ion implantation chamber, are described in detail on the basis of the experimental results.
The convergence time of the interdomain routing protocol, BGP, can last as long as 30 minutes. Yet, routing behavior during BGP route convergence is poorly understood. BGP can experience transient loss of reachability during route convergence. We refer to this transient loss of reachability during route convergence as transient routing failure. Transient routing failures can lead to end-to-end forwarding failures. Furthermore, the prolonged routing failures can make deploying applications such as voice-over-IP and interactive games infeasible. In this paper, we study the extent to which transient interdomain routing failures occur in the Internet and the duration that these failures can last through both analysis and measurement. We first present a formal model that captures the transient behavior of the interdomain routing protocol. We derive sufficient conditions for and an upper bound for the duration of transient routing failures. Furthermore, we demonstrate the occurrence and duration of transient routing failures in the Internet through measurement. We find that majority of transient failures occur under the commonly applied routing policy setting, and popular and unpopular prefixes can experience transient failures.
During the routing convergence processes of BGP system, the end-to-end reachability can be temporarily disrupted due to transient routing failures or loops in the forwarding paths. This could lead to severe performance degradation and even service disruption, especially for the real-time interactive applications. In this paper, we explore feasible modifications of BGP to eliminate transient routing failures and loops. First, we find that the existing BGP convergence acceleration solutions, such as ghost-flushing and EPIC, can eliminate transient forwarding loops but exacerbate transient routing failures. Then we propose an indicative re-routing scheme, which enable BGP to piggyback an indicator of alternative paths with each route, to improve route visibility and thus eliminate transient routing failures. However, we find that it might worsen transient forwarding loops at the same time. Finally, we exploit the synergy of the combination of the two types of schemes and propose an indicative+EPIC rerouting scheme. It is found capable of eliminating both transient forwarding failures and loops
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