Beijing Key Laboratory of Work Safety Intelligent Monitoring

Beijing, China

Beijing Key Laboratory of Work Safety Intelligent Monitoring

Beijing, China
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Yu C.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Yu C.,Beijing University of Posts and Telecommunications | Zhang Z.,Beijing Key Laboratory of Work Safety Intelligent Monitoring
China Communications | Year: 2017

To linearize the multi-band PAs/ transmitters, a serial of multi-band predistortion models based on multi-dimensional architecture have been proposed. However, most of these models work properly only for the signals whose harmonic and intermodulation products of carriers' non-overlap with the interested fundamental bands. In this paper, the non-overlapping conditions for dual-band and tri-band signals are derived and denoted in the form of closed-form expression. It can be used to verify whether a given dual-band/ multi-band signals can be linearized properly by these multi-dimensional behavioral models. Also the conditions can be used to plan the frequency spacing and maximum bandwidth of a multi-band or non-continuous carrier aggregation signal. Several dual-band and triband signals were tested on the same PA, by employing 2-D DPD and 3-D DPD behavioral models. The measurement results show that the signals which don't satisfy the non-overlapping conditions cannot be linearized well by the multi-dimensional behavioral models which does not take the harmonic and intermodulation products of carriers' into account. © 2013 IEEE.


Zhang H.-X.,Beijing University of Posts and Telecommunications | Zhang H.-X.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Han G.,Beijing University of Posts and Telecommunications | Li J.,Beijing University of Posts and Telecommunications | Li J.,China Information Technology Security Evaluation Center
Proceedings - 7th Asia-Pacific Conference on Environmental Electromagnetics, CEEM 2015 | Year: 2015

In the attack of the encryption algorithm ARCFOUR(RC4), new method of machine learning based on Wavelet Transform(WT) and Principal Component Analysis(PCA)is proposed. WT is used to reconstruct the new signals to extract information from the original signals effectively. Components in low and high frequency and reconstructed signals are made by WT. In order to analyze the impact of the signals on the success rate of prediction, four kinds of signals are adapted respectively for dimensionality reduction, which contains initial signals, reconstructed signals, and the signals in low and high frequency. By the classification of Support Vector Machine (SVM), the results show that the effect of the reconstructed signals is the best one. The reconstructed signals reduce the noise influence. In the range of 500 dimensions, the classification effect of the reconstructed signals is obviously better than others. As the dimension increases, the effect becomes small. The effect of signals in low frequency is more effective than that of the original in most of dimensions. The classification success rate is still high with fewer dimensions. In the four kinds of signals, the effect of the signals in high frequency is the worst. The results show that WT combined with PCA is a good method to handle with classification. © 2015 IEEE.


Zhang Y.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Zhang Y.,Beijing University of Posts and Telecommunications | Wang Z.,Beijing University of Posts and Telecommunications | Li J.,Beijing Information Science and Technology University | And 3 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

To promote the performance of Opportunistic Networks (ONs), novel network architecture with Fixed Infrastructure Nodes (FINs) is proposed. FINs have large storage capacity and short-range wireless communication ability. Two location strategies of FINs are compared in this paper including location at Points of Interest (POIs) and location at hot spots with high traffic. Routing protocol named PROPHET-F is proposed to employ the FINs' ability. The main difference between PROPHET-F and original PROPHET is that FINs own the highest message forwarding priority. FINs can collect all messages carried by the nodes passing by the FINs and transfer to other proper mobile nodes. The performance of this novel architecture is evaluated in ONE simulation platform. The simulation results indicate that Message Delivery Probability (MDP) in ONs with FINs is improved. MDP is higher while FINs are located at hot spots than at POIs. Furthermore, MDP of PROPHET-F protocol is superior to that of PROPHET. © 2013 Springer-Verlag.


Yin X.-L.,Beijing University of Posts and Telecommunications | Yin X.-L.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Tu J.-L.,Beijing University of Posts and Telecommunications | Chen Y.-L.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Communications | Year: 2013

Based on the optical architecture that uses optical pulse shaping to generate 24 GHz-band arbitrary impulse radio ultra-wideband (IR-UWB) signals, an optimization method is proposed to increase the spectral efficiency of the generated signals. Simulated annealing algorithm is used as the optimization method and the spectrum efficiency is utilized as the optimization condition. Numerical analysis shows that power-efficient FCC-Compliant IR-UWB signals are achieved for the given structure. Moreover, the relationship between the spectrum efficiency and the length of pulse trains and the robustness of the optical pulse shaper are analyzed. © 2012 Elsevier B.V.


Liu W.,Beijing University of Posts and Telecommunications | Liu W.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Yang J.,Beijing University of Posts and Telecommunications | Yang J.,Beijing Key Laboratory of Work Safety Intelligent Monitoring
Electronics, Communications and Networks IV - Proceedings of the 4th International Conference on Electronics, Communications and Networks, CECNet2014 | Year: 2015

In order to help household electrical appliance enterprise make decisions between different refrigerator interfaces and determine the future development direction of interface designing, this paper studies from two aspects: user interviews and usability testing. First, the characteristics of the user behavior and the operation while using the display control interface of refrigerators are studied and a usability test is conducted according to the problem found in the interviews in the refrigerated display control interface. This paper selects a group of objective measurements in the test to determine the usability level of three different refrigerator interfaces, and it also collects subjective ratings given by users. The result shows that the objective data this study chooses is not only consistent with the user subjective rating, but also useful in comparing the differences between similar interfaces. This paper is helpful for the enterprises that may have difficulty in choosing the product lines with development potential, and provides a reference for the future study of comparing the usability between similar products. © 2015 Taylor & Francis Group, London.


Liu W.,Beijing University of Posts and Telecommunications | Liu W.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Zhao Y.,Beijing University of Posts and Telecommunications | Zhao Y.,Beijing Key Laboratory of Work Safety Intelligent Monitoring
Electronics, Communications and Networks IV - Proceedings of the 4th International Conference on Electronics, Communications and Networks, CECNet2014 | Year: 2015

In this paper, the difficulty ratio logarithmic method is proposed to estimate the ability of testees based on IRT three element model during the CAT. Compared with the existing methods, it has the advantages of higher accuracy and less quantity of question needed to be tested. Another new method based on dichotomy is provided, which is dichotomy indefinite step method. Compared with the fixed-step method through experiment, it has the advantages of higher accuracy and higher efficiency. © 2015 Taylor & Francis Group, London.


Liu W.,Beijing University of Posts and Telecommunications | Liu W.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Dong W.,Beijing University of Posts and Telecommunications | Dong W.,Beijing Key Laboratory of Work Safety Intelligent Monitoring
Electronics, Communications and Networks IV - Proceedings of the 4th International Conference on Electronics, Communications and Networks, CECNet2014 | Year: 2015

This study presents an improved question recommendation model based on previous research of question recommendation systems and related technologies. This model can recommend a list of documents to users according to those questions. Initially, the text corpus was trained to obtain the latent topics and parameters using a Latent Dirichlet Allocation (LDA) model. The processed questions and corpus was transformed into corresponding word vectors using the neural network algorithm in the Word2Vec toolset. The weighted cosine similarity was calculated in order to obtain the relevance of the questions to the documents. After being sorted by relevance, the documents were given to users. This method combined the advantages of using both the language and probability models. Furthermore, it improved the precision of the question recommendation, which is demonstrated in this study. © 2015 Taylor & Francis Group, London.


Liu W.,Beijing University of Posts and Telecommunications | Liu W.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Xue W.,Beijing University of Posts and Telecommunications | Xue W.,Beijing Key Laboratory of Work Safety Intelligent Monitoring
Electronics, Communications and Networks IV - Proceedings of the 4th International Conference on Electronics, Communications and Networks, CECNet2014 | Year: 2015

The car cab display interface is a very important human-machine interaction interface for predicting information. In terms of the car design, due to the complex traffic environment, the display interface must provide enough Situation Awareness (SA) for the driver to ensure driving safety and SA is frequently considered to improve the design. In order to study the driver’s SA in the car system, a driving simulation environment is built, including a virtual interface display system and a driving data record and control system. Based on the above environment, with SA and the instantaneous Heart Rate (HR) as reference factors, the experiments are conducted to study the driver’s SA ability under different display interfaces through Situation Awareness Global Assessment Technique (SAGAT) and psychological measurement to assess the cab display interface. The results show the display interfaces significantly affect SA, and then offer a suggestion to optimize the car cab display interface design. © 2015 Taylor & Francis Group, London.


Liu W.,Beijing University of Posts and Telecommunications | Liu W.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Zhao Y.,Beijing University of Posts and Telecommunications | Zhao Y.,Beijing Key Laboratory of Work Safety Intelligent Monitoring
Electronics, Communications and Networks IV - Proceedings of the 4th International Conference on Electronics, Communications and Networks, CECNet2014 | Year: 2015

An algorithm of sinc interpolation to improve frequency resolution based on FFT spectrum analysis system is given in this paper. This algorithm is different with existing 4 main methods, which is more simple and adaptable. By using this algorithm, we can analysis FFT spectrum, fix error on signal amplitude, Signal frequency and Signal phase caused by spectrum leakage for fence effect. The accuracy of signal amplitude and signal frequency can meet about 5 significant digits after the decimal point and the accuracy of signal phase also can meet 2 significant digits after the decimal point. By using Fourier analysis in numerical analysis module of Excel, we achieve numerical simulation and verify the feasibility of the algorithm. Using Matlab to deal the signal collected by digital storage oscilloscope or Arbitrary Waveform Generator, we do Fast Fourier Transform of the signal, correct spectrum and give out error correction. © 2015 Taylor & Francis Group, London.


Ge H.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Yao Y.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Yu J.,Beijing Key Laboratory of Work Safety Intelligent Monitoring | Chen X.,Queen Mary, University of London
IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) | Year: 2014

In this paper, a novel experimental solution for the characterization of the binary input impedance of Ultra High Frequency (UHF) band Radio Frequency Identification (RFID) transponder chip is presented. The proposed method is easy to setup using common test instruments. The tag chip is directly soldered to a 50-Ω subminiature A (SMA) connector, and then connected to a vector network analyzer (VNA) and a RFID emulator through a three ports power divider. The impedances measurement results with respect to frequency and input power on the chip are useful in practical RFID applications for optimal tag antenna design in order to enhance the entire RFID system performance. © 2014 IEEE.

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