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While the bandwidth and latency improvement of both WiFi and cellular data networks in the past decade are plenty evident, the extent of signal strength fluctuation and network disruptions (unexpected switching or disconnections) experienced by mobile users in today's network deployment remains less clear. This paper makes three contributions. First, we conduct the first extensive measurement of network...
The SGII-Up laser facility is one of the most important high power laser system in china. The maximum output of one beam is studied, and it is improved to 17600J from initial 5000J.
Energy consumption has become a key issue for running large-scale data center networks (DCN) nowadays. Previous studies mainly focus on energy saving through reducing the number of active servers or network switches with traffic consolidation. However, since this mechanism benefits from the routing flexibility, both the gained energy savings and flow performance are limited by the conventional static...
We have successfully demonstrated a smart UV patch to memorize the accumulative energy from the exposure to UV light over a period of time. The sensing principle is based on changes in the electrical resistance of a composite made of photo-acid generator triphenyl sulfonium triflate (TST), poly aniline emeraldine (PANI-EB), polyethylene glycol (PEG) and carbon nanotubes (CNTs). The sheet resistance...
This work reveals a new AC sensing scheme to achieve a fast recovery and minimal baseline drift of gas sensors based on graphene FETs. Compared with the state-of-art technologies, three distinctive advancements have been achieved: (1) first demonstration of using the AC phase lag signal between channel resistance and gate voltage as a sensitive gas detection scheme on graphene FETs; (2) achieving...
Despite that IaaS users are busy scaling up/out their cloud instances to meet the ever-increasing demands, the dynamics of their demands, as well as the coarse-grained billing options offered by leading cloud providers, have led to substantial instance underutilization in both temporal and spatial domains. This paper theoretically examines an instance subletting service, where underutilized instances...
This paper reports the investigation of low-frequency noise (1/f noise) in the Polyethylenimine (PEI) doped graphene gas sensor based on the architecture of using chemical vapor deposition (CVD) to make a graphene field effect transistor (GFET). Compare to the state-of-art, three advancements have been achieved: (1) first demonstration of 1/f noise characterization in PEI doped CVD graphene FET sensor...
Cloud storage services such as Dropbox have been widely used for file collaboration among multiple users. However, this desirable functionality is yet restricted to the “walled-garden” of each service. At present, the only effective approach to cross-cloud file collaboration seems to be using web APIs, whose performance is known to be highly unstable and unpredictable. Now that using inefficient web...
Range finding is a core service in many applications for smart homes and cities. Recently studies have been exploring ultrasound-based range finding with commercial-off-the-shelf (COTS) mobile devices. Yet their accuracy is largely bounded by the limited sample rate (typically up to 48 kHz; i.e. only sensitive to sound below 24 kHz) of their built-in microphones and chips. In this paper, we introduce...
This work presents a new class of gas sensing scheme: the phase sensitive signal on the GFET (Graphene Field Effect Transistor) gas sensors aiming to boost the response speed. Compared with the state-of-art gas sensing reports on measurements of DC resistance changes which are limited by trap states, three distinctive advancements have been achieved on graphene FETs in responses to water vapor: (1)...
The exhaustion of IPv4 addresses has led to the transition to IPv6 becoming a major task for the Internet. Providing IPv6 users with accessibility to IPv4 services has been one of the most challenging tasks during the IPv4/IPv6 transition. However, some protocols contain IP addresses in the application layer, resulting in incompatibilities in traversing the network-layer translators. In this paper,...
With the feed-in of electricity proportion rising, Shanghai grid become a typical large city Receiving-end grid. Voltage stability make great influence to power grid operating safely and stably. Firstly, brief introduction of Shanghai power grid current situation. Secondly, analyze summer and winter voltage stability of Shanghai power grid in different operation modes, including normal operation and...
A 1000V, high-voltage planar micro-supercapacitor directly fabricated on a flexible polymer substrate has been demonstrated to successfully power an electrostatic cantilever microresonator for more than 1 minute. Direct-write laser engraving of Kapton tape (polyimide) was used to fabricate each 200V micro-supercapacitor rapidly in a single step at ambient condition for the first time. To actuate the...
Virtual machine (VM) migration is a key technique for network resource optimization in modern data center networks (DCNs). Previous work generally focuses on how to place the VMs efficiently in a static network topology by migrating the VMs with large traffic demands to close servers. When the VM demands change, however, a great cost will be paid on the VM migration. With the advance of software-defined...
The uncertainties of wind power have a great influence on the static voltage stability of power systems. The effect of uncertainty and correlation of wind power on the static voltage stability is studied in this paper and the static voltage stability is analyzed on the basis of probabilistic load flow (PLF). Moreover, quasi-Monte Carlo using Sobol sequences is adopted to obtain the samples of input...
Modular multilevel matrix converter (M3C) is a new topology of AC/AC power converter, with broad application prospects in grid connecting of passive networks, especially offshore wind farm. In this paper, the circuit configuration and operation mechanism of M3C based transmission system supplying passive networks are introduced. A generalized mathematical model for the system is deduced by implementing...
As substantial power is imported into Shanghai Grid through four HVDC systems, the operation characteristics of multi-infeed receiving-end system have emerged in Shanghai Grid. The intensive interactions between HVDC system and AC grid may aggravate the risk of cascading as well as the capability of the grid to withstand significant disturbances. In this paper, simulation of HVDC system response upon...
Fractional frequency transmission system (FFTS) is a promising solution to offshore wind power integration. The back-to-back modular multilevel converter (MMC) and modular multilevel matrix converter (M3C) are universally regarded as two promising ac/ac converter candidates of the next generation. This paper performs a detailed comparison between back-to-back MMC and M3C with special emphasis on their...
The characteristics of DC system control and protection programs are analyzed for ABB and Siemens HVDC systems. The detailed model for full-process simulation of steady-state and transient response of HVDC system is established through combining RTDS component library and user-defined modeling by CBuilder. Simulation of steady-state and transient response of HVDC system is performed based on the model...
As multi-infeed HVDC systems are integrated into East China Grid, the operation characteristics and concerns of the grid have changed remarkably. Due to substantial power import through HVDC systems, a large quantity of local generators in the receiving-end grid have to be shut down. The resulting aggravated shortage of dynamic reactive power reserve exacerbates the capability of the grid to withstand...
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