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He T.,UESTC | Rui D.,UESTC | Yong H.,UESTC | Zhang J.,UESTC
International Conference on Signal Processing Proceedings, ICSP | Year: 2017

In this paper, a phased array beamforming method based on the rotational platform is proposed. According to this method, the height of a platform can be measured accurately by adjusting the azimuth and elevation angles to keep the beam always point to the nadir point. Thus, the phased array altimeter needs to compensate the intersection change of the beam-point and the nadir point as a consequence of the platform translation and rotation. This paper deduces functions of angle error and phase compensation to calibrate the beam-point by establishing motion model of the platform, provides the method of weight calculating, and analyzes the update rate of weight. The curves illustrating the changes in directions of beam point as azimuth and elevation change respectively are provided by simulating. Finally, by means of simulation, making comparison between compensated and non-compensated antenna beam direction, we find the non-compensated beam is off nadir point with the changing motion of platform, while after compensating, the beam can be calibrated and pointed to the nadir again. © 2016 IEEE.


Liu Z.,University of California at Riverside | Tan S.X.-D.,University of California at Riverside | Wang H.,UESTC | Swarup S.,University of California at Riverside | Gupta A.,Intel Corporation
Proceedings of the Asia and South Pacific Design Automation Conference, ASP-DAC | Year: 2013

This paper proposes a new thermal nonlinear modeling technique for packaged integrated systems. Thermal behavior of complicated systems like packaged electronic systems may exhibit nonlinear and temperature dependent properties. As a result, it is difficult to use a low order linear model to approximate the thermal behavior of the packaged integrated systems without accuracy loss. In this paper, we try to mitigate this problem by using piecewise linear (PWL) approach to characterizing the thermal behavior of those systems. The new method (called ThermSubPWL), which is the first proposed approach to nonlinear thermal modeling problem, identifies the linear local models for different temperature ranges using the subspace identification method. A linear transformation method is proposed to transform all the identified linear local models to the common state basis to build the continuous piecewise linear model. Experimental results validate the proposed method on a realistic packaged integrated system modeled via the multi-domain/physics commercial tool, COMSOL, under practical power signal inputs. The new piecewise models can lead to much smaller model order without accuracy loss, which translates to significant savings in both the simulation time and the time required to identify the reduced models compared to applying the high order models. © 2013 IEEE.


Shi K.,Shanghai JiaoTong University | Li L.,UESTC | Liu H.,Shanghai JiaoTong University | He J.,Zhejiang University | And 2 more authors.
CCIS2011 - Proceedings: 2011 IEEE International Conference on Cloud Computing and Intelligence Systems | Year: 2011

Text classification has gained booming interest over the past few years. As a simple, effective and nonparametric classification method, KNN method is widely used in document classification. However, the uneven distribution in training set will affect the KNN classified result negatively. Moreover, the uneven distribution phenomenon of text is very common in documents on the Web. To tackling on this, this paper proposes an improved KNN method denoted by DBKNN. Experimental results show that the DBKNN algorithm can better serve classification requests for large sets of unevenly distributed documents. © 2011 IEEE.


Liu Y.,Sichuan University | Li L.,Sichuan University | Li Z.,Sichuan University | Ye Y.,UESTC
2013 International Conference on Communications, Circuits and Systems, ICCCAS 2013 | Year: 2013

Mobile Social Networks (MSNs), as a type of Delay Tolerant Networks (DTNs) automatically structured by portable devices, have aroused great attention. Comparing with conventional DTNs, data routing in MSNs is a stronger challenge, due to the existence of the nodes' social selfishness, a inherent social attribute of Mobile Social Networks. Social selfishness causes a node is just willing to forward data for its trustful nodes, which makes packets forwarding more difficult in the MSNs. Epidemic routing provides an effective way to deliver packets in socially selfish MSNs, but the adaptability of Epidemic to different network selfishness degrees is not very good. To improve routing adaptability, in this paper, the trust degree metric is firstly defined to depict a node's packet forwarding capability based on node's own trust relationships. And then the trust degree threshold-based Optimized Routing Scheme is introduced, in which the parameter of trust degree threshold can be used to adjust copy spread probability in various selfishness degree networks, so as to enhance the adaptability of routing to network selfishness degrees. Based on the quantitative description of the relationship of the trust degree threshold to the spread probability, simulation shows that the Optimized Routing Scheme is adaptive to various network selfishness degrees and the routing performance can effectively be improved when rationally setting the trust degree threshold parameter. © 2013 IEEE.


Zhong H.S.,UESTC | Guan L.,Automotive Semiconductor Supplier | You W.,UESTC
SAE Technical Papers | Year: 2015

The torque sensing module is an important part of EPS (Electronic Power Steering) system. There are various solutions in the market based on different technologies i.e. Potential meter, Inductive and Hall sensing. As a trend, more and more EPS system integrators adopt Hall-based torque sensing solution, most of which consist of a magnetic ring, a magnetic flux detector to read the magnetic flux from the magnetic ring and a flux conductor/concentrator to lead the magnetic signal to a Hall device to convert magnetic flux level to electronic signal. However, available solutions require high mechanical precision from the magnetic flux detector and conductor/concentrator. Also, the magnetic ring in the existing solution is magnetized after its preformation which causes a lower signal-to-noise ratio at the input of the entire system due to the process and brings about less accuracy of the torque sensing module. In order to overcome these obstacles, a new torque sensing module design based on Hall sensing principles is proposed in this paper. This article provides a brief background of the current market and technical situation will be introduced, followed by explanations on Hall-based magnetic torque sensing module in terms of operation principles. Then new design of the torque module will be proposed. Next, a detailed magnetic analysis will be shown. Based on this analysis, this paper will present the simulation results. Copyright © 2015 SAE International.


Zhang J.,University of Wisconsin - Madison | Zhang X.,University of Wisconsin - Madison | Wu G.,UESTC
Proceedings - IEEE INFOCOM | Year: 2015

Visible Light Communications (VLC) is emerging as an appealing technology to complement WiFi in indoor environments. Yet maintaining VLC performance under link dynamics remains a challenging problem. In this paper, we build a VLC software-radio testbed and examine VLC channel dynamics through comprehensive measurement. We find minor device movement or orientation change can cause the VLC link SNR to vary by tens of dB even within one packet duration, which renders existing WiFi rate adaptation protocols ineffective. We thus propose a new mechanism, DLit, that leverages two unique properties of VLC links (predictability and full-duplex) to realize fine-grained, in-frame rate adaptation. Our prototype implementation and experiments demonstrate that DLit achieves near-optimal performance for mobile VLC usage cases, and outperforms conventional packet-level adaptation schemes by multiple folds. © 2015 IEEE.


Ma H.,UESTC | Li Y.,UESTC
2012 Spring World Congress on Engineering and Technology, SCET 2012 - Proceedings | Year: 2012

High dynamic GPS signal simulator is an indispensable instrument for the testing of high dynamic GPS receivers. The high dynamic GPS signal simulator consists of hardware, computer and software. The software comprises the error simulation models, the carrier moving trajectory simulation models and the satellite navigation parameters, etc. The carrier moving trajectory simulation models is a key technique that the high dynamic GPS signal simulator must solve. The carriers are divided into satellites, missiles, airplanes, ships and automobiles. The target trajectory simulation models are set up respectively according to their moving rules. In order to get the convenience to users, as long as a user inputs proper parameters, the carrier moving trajectory can be generated automatically by the simulator. © 2012 IEEE.


Li J.L.-W.,UESTC
2012 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition, iWEM 2012 | Year: 2012

Conference proceedings front matter may contain various advertisements, welcome messages, committee or program information, and other miscellaneous conference information. This may in some cases also include the cover art, table of contents, copyright statements, title-page or half title-pages, blank pages, venue maps or other general information relating to the conference that was part of the original conference proceedings. © 2012 IEEE.


Zhang Z.,UESTC | Zhang Z.,Ecole Polytechnique Federale de Lausanne | Mara O.,Ecole Polytechnique Federale de Lausanne | Argyraki K.,Ecole Polytechnique Federale de Lausanne
SIGCOMM 2014 - Proceedings of the 2014 ACM Conference on Special Interest Group on Data Communication | Year: 2014

When can we reason about the neutrality of a network based on external observations? We prove conditions under which it is possible to (a) detect neutrality violations and (b) localize them to specific links, based on external observations. Our insight is that, when we make external observations from different vantage points, these will most likely be inconsistent with each other if the network is not neutral. Where existing tomographic techniques try to form solvable systems of equations to infer network properties, we try to form unsolvable systems that reveal neutrality violations. We present an algorithm that relies on this idea to identify sets of non-neutral links based on external observations, and we show, through network emulation, that it achieves good accuracy for a variety of network conditions. © 2014 ACM.


Yun-Sheng W.,UESTC
AIAA/IEEE Digital Avionics Systems Conference - Proceedings | Year: 2012

IMA is an embedded version of a centralized time-shared 'mainframe', which provides: shared high performance common computing resources, high speed communication network, open architecture for both software and hardware. © 2012 IEEE.

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