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Molecular orbital tomography (MOT) opens up a window to probe molecular structure with high-order-harmonic generation. A major difficulty in MOT is the measurement of harmonic phase, which is usually quite complicated in experiment. In this work, we experimentally demonstrate that this can be overcomed by combining both MOT and diffractive imaging.
This paper proposes an attack pattern mining algorithm to extract attack pattern in massive security logs. The improved fuzzy clustering algorithm is used to generate sequence set. Then PrefixSpan is used to mine frequent sequence from the sequence set. The experimental results show that this algorithm can effectively mine the attack pattern, improve the accuracy and generate more valuable attack...
The continuous fluctuation of electric network frequency (ENF) presents a fingerprint indicative of time, which we call natural timestamp. This live demo demonstrates the accuracy of the natural timestamps obtained by four wired voltage sensors and four wireless electromagnetic radiation (EMR) sensors that are geographically distributed in Singapore. The voltage sensors and the EMR sensors capture...
The continuous fluctuation of electric network frequency (ENF) presents a fingerprint indicative of time, which we call natural timestamp. This paper studies the time accuracy of these natural timestamps obtained from powerline electromagnetic radiation (EMR), which is mainly excited by powerline voltage oscillations at the rate of the ENF. However, since the EMR signal is often weak and noisy, extracting...
The DC conduction of transformer oil and transformer oil-based nanofluids were investigated with increasing electric field strength in this paper. The results show that entire process of conduction can be divided into three stages, including resistance stage, tunneling stage and space-charge limited stage. Further analysis indicate that the generation and movement mechanism of carriers are different...
Oil impregnated paper is an important solid insulation dielectric in power transformers. Thus it is very significant to understand the dielectric properties of the oil impregnated paper. In this paper, a conductivity measuring system was built to explore the conduction mechanism of oil impregnated paper. This measuring system is able to measure the conduction current in the samples. Based on the system,...
Online Social Networks (OSNs) have become a rewarding target for attackers. One particularly popular attack is the Sybil attack, in which the adversary creates many fake accounts called Sybils in order to, for instance, distribute spam or manipulate voting results. A first generation of defense systems tried to detect these Sybils by analyzing changes in the structure of the OSN graph---unfortunately...
The network link speed is increasing at an alarming rate, which requires all network functions on routers/switches to keep pace. Bloom filter is a widely-used membership check data structure in network applications. It also faces the urgent demand of improving the performance in membership check speed. To this end, this paper proposes a new Bloom filter variant called Ultra-Fast Bloom Filters, by...
Recently, visual features extracted by convolutional neural networks (CNNs) have been widely used in computer vision. Most state-of-the-art CNNs adopt a convolutional layer to map the high dimensional features into the number of the output classes. However, it is not good enough for feature similarity comparison. So we propose a new layer, Euclidean output layer, for extracting discriminative features...
In low-voltage ride-through or unbalance gird voltage condition, the fundamental fluctuation in the neutral-point (NP) voltage of three-level voltage source converter will appear under imbalanced grid voltage situation and has not been researched in detail. A new NP current model under imbalanced grid is developed to investigate the limitations of conventional nearest-vector modulation and to give...
Operating thermal generators flexibly enables them to achieve higher ramping up or down rates than usual. In this way, thermal generation can better follow the fluctuations of wind power, and the allowable penetration level of wind energy can thus be increased in the grid. In this paper, we analyze the sensitivity of allowable system wind penetration level to thermal generation ramp rates in an economic...
Overhead earth wire breakage accident may occur frequently, which can seriously affect the reliable operation of the power grid. The main reason of the earth wire breakage is the contact resistance inside the clamp as short-circuit current flows through it. To understand the mechanism of the earth wire breakage, this paper conducts the theoretical study on the skin effect and contact resistance of...
Based on basic electrochemical principles, an equivalent circuit model of a Li-ion battery is developed. The eventual aim of the work is to use such a model in the accurate control of power flow for a battery energy storage system (BESS) in grid-scale applications. The model developed here allows one to monitor the BESS internal states, by taking into consideration the internal dynamics of the battery...
We propose AccountTrade, a set of accountable protocols, for big data trading among dishonest consumers. To secure the big data trading environment, our protocols achieve book-keeping ability and accountability against dishonest consumers who may misbehave throughout the dataset transactions. Specifically, we study the responsibilities of the consumers in the dataset trading and design AccountTrade...
In a software defined network (SDN), the control plane needs to frequently collect flow statistics measured at the data plane switches for different applications, such as traffic engineering, flow re-routing, and attack detection. However, existing solutions for flow statistics collection may result in large bandwidth cost in the control channel and long processing delay on switches, which significantly...
In edge-cloud computing, a set of edge servers are deployed near the mobile devices such that these devices can offload jobs to the servers with low latency. One fundamental and critical problem in edge-cloud systems is how to dispatch and schedule the jobs so that the job response time (defined as the interval between the release of a job and the arrival of the computation result at its device) is...
Gas Insulted Switcher (GIS) is one of the most important equipments in power system. Partial discharges (PDs) detection has the vital significance to the condition diagnosis of GIS. In this paper, a multispectral optical PD detection system based on three photomultipliers (PMs) with corresponding light filters in the front is built to detect PD under power frequency voltage. The variations of the...
The research on partial discharge at the surface of the insulation material is very necessary, which will cause electrical aging and insulation failure. Due to the strong ability of anti-electrical tree of micron aluminum oxide, it is widely added to the epoxy resin matrix to enhance the resistance on electrical insulation aging ability of the insulating composite material. In order to strengthen...
Hub motor driven pure electric vehicle's transmission structure is simple and the driving wheel torque is controlled independently of each other. When the vehicle turns, both sides of the hub motor around the main pin to produce differential torque, so it can be flexible control of vehicle steering. In this paper, the hub motor driven pure electric vehicle as a prototype, side-slip angle and angular...
A passive (power-less), bending type MEMS DC current sensor to satisfy the increasing needs of DC power supply for monitoring the electricity consumption by either one-wire or two-wire appliance cord was proposed in our past work (DTIP 2011). A MEMS-scale prototype DC sensor, comprised of 5 parallel PZT plates, was then micro-fabricated for preliminarily examination (DTIP 2012). A novel oscillating...
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