Dynamic Model and Quantitative Analysis of Stick-Slip Vibration in Horizontal Well by Baojin Wang, Zhongyang Wang, Fushen Ren

“…The drillstring-borehole impact and friction, fluid-structure interaction, bit-rock interaction, and gravity are considered in this model. …”
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Theoretical and Numerical Analysis of Coupled Axial-Torsional Nonlinear Vibration of Drill Strings by Xinye Li, Tao Yu, Lijuan Zhang, Hao Zeng, Congcong Duan

“…The variation of parameters may lead to the complex dynamic behavior of the system, such as period-doubling motion, quasiperiodic motion, and chaos. Bit bounce and stick-slip phenomenon can be effectively suppressed by varying the angular velocity of turntable and nominal drilling pressure.…”
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Novel level shifter based physical unclonable function circuit design by Lijuan HAN, Lei QIAN, Enyi YAO, Xin LOU, Yuan CAO, Yanhua LIU

“…Level shifters are widely used in low-power, multi-threshold integrated circuit chips.A novel physical unclonable function (PUF) design based on cross-coupled level shifter was proposed.In this work, a single switching transistor was inserted in the level shifter, which was the only overhead per response bit to change the operation mode of the cross-coupled level shifter from differential to common.The signature of the PUF was extracted while in common mode, by exploiting the uncertainty of the output voltage due to the difference of the switching time of the two PMOS in the cross-coupled network.Simulated with a standard 65 nm CMOS process, the results show the proposed PUF can produce a uniqueness of 49.11% and a reliability of 96.09% with the power supply voltage ranged from 1.0 V to 1.5 V and 95.31% with the temperature ranged from -20 ℃ to 100 ℃.The energy per bit is only 0.72 pJ at a high throughput of 20 Mbit/s (1.2 V, 27 ℃).…”
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Improved sub-band JND model with textural decomposition and its application in perceptual image coding by Ming-kui ZHENG, Kai-xiong SU, Wei-xing WANG, Cheng-dong LAN, Xiu-zhi YANG

“…Experimental results show that the proposed algorithm can improve the JND threshold;compared with JPEG standard, the perceptual coding method can save more bit rate and does not need extra bit for auxil-iary information at the similar visual quality. …”
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Performance of FTH-PPM multiple access technology in 60 GHz wireless communication system by Chen SHEN, Xuehua LI

“…Aiming at the problem of multiple access interference in 60 GHz pulse wireless communication system,the performance of system based on FTH-PPM multiple access scheme was studied.Under the IEEE 802.15.3.c channel model,the relationship between the bit error rate performance of the system and the number of frequency hopping codes,the signal to noise ratio and the number of users were analyzed.The characteristics of FTH-PPM multiple access modulation system were studied and compared with TH-PPM and TH-PAM schemes.The simulation results show that the system can meet the required bit error rate by changing the signal to noise ratio,the number of hops and the number of users.At the same time,the BER performance of FTH-PPM is better than that of TH-PAM and TH-PPM.The system can select the appropriate multiple access modulation mode according to the value of the pulse duty cycle.The research will provide technical reference for the application of 60 GHz pulse wireless communication.…”
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Three-dimensional polarization amplitude modulator and demodulator by Han-bin SONG, Jun-bo ZHANG, Xiao-guang CHEN, Jian-qiu ZHANG

“…Based on the mathematical description of a space electromagnetic field,a novel approach to the three-dimen-sional joint modulation of the signal amplitude,polarization angle and polarization phase angle of an electromagnetic signal in wireless communication was presented.The model of the three-dimensional modulation signal was first given by the equations of the relationship among the parameters of a space electromagnetic field.Then,the transmission im-plementation of the three-dimensional joint modulation signal was discussed by a vector antenna.At the receiving end,a signal amplitude detection and DOA polarization parameter estimation method was given to demodulate the received three-dimensional joint modulation signal.The bit error rate and performance of the proposed three-dimensional joint modulator and demodulator were analyzed.Both the analysis and the simulation results show that a high information transmission and a low bit error rates can simultaneously be obtained by the proposed method.…”
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An adaptive video stream transmission control method for wireless heterogeneous networks based on A3C by Zhiqiang LUO, Wei WANG, Xiaorong ZHU

“…The adaptive bit rate (ABR) algorithm has become the focus research in video transmission.However,due to the characteristics of 5G wireless heterogeneous networks,such as large fluctuation of channel bandwidth and obvious differences between different networks,the adaptive video stream transmission with multi-terminal cooperation was faced with great challenges.An adaptive video stream transmission control method based on deep reinforcement learning was proposed.First of all,a video stream dynamic programming model was established to jointly optimize the transmission rate and diversion strategy.Since the solution of this optimization problem depended on accurate channel estimation,dynamically changing channel state was difficult to achieve.Therefore,the dynamic programming problem was improved to reinforcement learning task,and the A3C algorithm was used to dynamically determine the video bit rate and diversion strategy.Finally,the simulation was carried out according to the measured network data,and compared with the traditional optimization method,the method proposed better improved the user QoE.…”
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Collision analysis of the GMR-2 cipher used in the satellite phone by Ruilin LI, Jiao HU, Chaojing TANG

“…A collision property analysis of the GMR-2 cipher used in the satellite phone was presented.By using the F-component as a bridge,the link between the difference of the key byte and the collision of the output ofFas well as the link between the collision of the output of F and the collision of keystream byte were analyzed,which finally revealed the relationship between the difference of the original key byte and the keystream collision.The theoretical analysis showed that for a random frame number,a special chosen key pair could lead to a keystream collision with a high probability,when the key pair has only one byte difference in which the most significant 4 bit of the difference was equal to the last significant 4 bit.The experimental result shows that the keystream collision probability is 2^−8.248,which is far higher than the ideal collision probability 2⁻¹²⁰.This proves once again,that there exists serious potential security hazards in the GMR-2 cipher.…”
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Algebraic fault attack on PRESENT by Ke-hui WU, Xin-jie ZHAO, Tao WANG, Shi-ze GUO, Hui-ying LIU

“…A new fault analysis method on PRESENT—algebraic fault attack was proposed.This attack combined conventional algebraic cryptanalysis with fault attack,firstly built equivalent Boolean algebraic equations of cipher encryption by algebraic cryptanalysis method; secondly got information of fault cryptograph by fault attack technique,and transformed differential of fault and cryptograph into additional algebraic equations; finally utilized Crypto Mini SAT solver to solve the equations and recover key.Experiments demonstrate that after injecting 4-bit fault to the 29^th round of PRESENT-80,the fault location and fault value are unknown,only 2 injectings can recover 64-bit last whitening key in 50 seconds that reduce master key of PRESENT-80 searching space to 2¹⁶,then recover the master key after 1 minute brute-force-search on average; compared with previous fault attack on PRESENT,the amount of this attack sample is the smallest;meanwhile,the analysis method proposed can be applied into the algebraic fault attack of other block ciphers.…”
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Efficient implementation scheme of SM4 algorithm based on FPGA by ZHANG Hongke, YUAN Haonan, DING Wenxiu, YAN Zheng, LI Bin, LIANG Dong

“…A combination of cyclic key extension and 32 bit pipeline encryption and decryption architecture was adopted by the proposed scheme. …”
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Research on the system error performance of coherent orthogonal frequency division multiplexing system with M-distribution in satellite-to-ground laser communication by Yi WANG, Yaping WANG

“…In order to alleviate the influence of atmospheric turbulence on the performance of satellite-to-ground laser communication system,based on the M-distribution atmospheric channel model,a multi-carrier coherent orthogonal frequency division multiplexing (OFDM) modulation system was proposed for uplink and downlink in the satellite-to-ground laser communication.The closed-form expression of bit error rate (BER) of coherent OFDM modulation system was derived.The relationship between the zenith angle,receiving aperture,signal-to-noise ratio (SNR),optimal beam divergence angle,and optimal transmission radius and the BER were studied under weak,and strong atmosphere turbulence,and compared with binary coherent differential phase shift keying (DPSK) modulation.Both the theory and the simulation results show that compared with coherent DPSK modulation,the bit error performance of the coherent OFDM modulation system in the satellite-to-ground laser communication system is better.…”
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H.264 SVC Complexity Reduction Based on Likelihood Mode Decision by L. Balaji, K. K. Thyagharajan

“…The comparison parameters are time, PSNR, and bit rate. LMD achieve time saving of 66.65% with 0.05% detriment in PSNR and 0.17% increment in bit rate compared with the full search method.…”
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Semi-fragile video watermarking algorithm for H.264/AVC based on cost strategy by Wei-wei ZHANG, Chen ZHAO, De-tian HUANG, Pei ZHANG, Yi-xian YANG

“…In order to solve some existing problems on detecting malicious tampering by video watermarking based on H.264/AVC video compression standard,a semi-fragile video watermarking algorithm for H.264/AVC based on cost strategy was proposed.To further improve the robustness of the feature codes in semi-fragile video watermarking algorithm,a new generation algorithm for feature codes by eliminating the correlation of them was proposed.In order to meet the requirement that the semi-fragile watermarks should be uniformly embedded into the video frames to locate the tampered region accurately,a minimal cost function was introduced to select a DCT coefficient in the 4 × 4 block residual to embed watermark which had minimal impact on the video quality and bit rates.Experimental results show that the proposed algorithm can significantly reduce impact on video quality and bit rate because of embedding the watermarking by adopting the minimum cost function and it is sensitive to malicious manipulations.The retrieved feature code and watermarking can detect and locate malicious manipulations.…”
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Reinforcement Learning-Based Autonomous Soccer Agents: A Study in Multi-Agent Coordination and Strategy Development by Biplov Paneru, Bishwash Paneru, Ramhari Poudyal, Khem Poudyal

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Performance analysis of RIS-assisted mixed RF/THz system by Sai LI, Liang YANG, Qimei CUI, Siyuan YU

“…To solve the problem of the short transmission distance of terahertz (THz) links, the performance of the reconfigurable intelligent surface (RIS)-assisted mixed dual-hop radio frequency (RF)/THz system was studied.An RIS was used to enhance signal strength, thereby improving the system performance.Using the fixed-gain amplify-and-forward protocol, the cumulative distribution function and probability density function of the end-to-end signal-to-noise ratio of the RF/THz link were derived.Capitalizing on the statistical characteristics, the analytical expressions of outage probability, average bit error rate, and average channel capacity of the mixed relaying system were further derived.In addition, the asymptotic analyses of the outage probability and the average bit error rate were carried out to obtain the diversity order of the mixed RF/THz system.Simulation results show that the RIS can effectively improve the performance of the mixed RF/THz system.Furthermore, the system performance is related to the channel fading, pointing errors, and propagation distance.…”
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Formulas for Rational-Valued Separability Probabilities of Random Induced Generalized Two-Qubit States by Paul B. Slater, Charles F. Dunkl

“…The associated induced-measure separability probabilities (k=1,2,…) are found—via a high-precision density approximation procedure—to assume interesting, relatively simple rational values in the two-re[al]bit (α=1/2), (standard) two-qubit (α=1), and two-quater[nionic]bit (α=2) cases. …”
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Physical layer security of MIMO wireless systems with adaptive modulation by Hui LI, Guangqiu LI, Yancui LUO, Huizhi LIU

“…To solve the problems of low spectral efficiency and poor performance of physical layer security (PLS) in single-input single-output (SISO) wireless systems with adaptive modulation in the presence of an active eavesdropper, multiple-input multiple-output (MIMO) wireless systems with secure adaptive modulation (SAM) were proposed.The design idea was to improve the spectral efficiency of the main channel by antenna diversity technology, which used the transmit antenna selection (TAS) at the transmitter and the maximal ratio combining (MRC) at the legitimate receiver to improve the signal-to-noise ratio.Simultaneously, the PLS of the legitimate receiver was guaranteed by limiting the bit error rate of the active eavesdropper so that it could not demodulate the confidential information from the main channel.With the joint constraints of the average transmission power and PLS, the optimal switching thresholds and the analytical expressions of spectral efficiency and the eavesdropper’s average bit error rate of the SAM-MIMO systems were derived.Numerical and simulation results show that SAM systems using TAS/MRC technology can not only improve the spectral efficiency of the main channel, but also ensure the PLS against the active eavesdropper, compared with the SAM-SISO systems.…”
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Large-scale terminal access algorithm based on slot ALOHA and adaptive access class barring by Zhenyu ZHU, Xiaorong ZHU, Yan CAI, Hongbo ZHU

“…In order to solve the problem of high collision rate and low timeliness of large-scale terminals access in the Internet of things, a large-scale terminal access algorithm based on slot ALOHA and adaptive access class barring (ACB) was proposed.Firstly, the services were classified based on the data from each terminal by the volume of the services processed and the requirements for delay.For the services that were not time-sensitive and whose effective data portion was less than 1 000 bit, a slot-based ALOHA-based competitive access method was used.ACB-based random access was used for the services that were time-sensitive or whose data portion was greater than 1 000 bit.On this basis, a method was proposed for predicting the access application volume based on the quantitative estimation, and dynamically adjusting the ACB control parameters based on this predicted value.Simulation results show that compared with other existing access algorithms, the proposed algorithm reduces the collision rate and improves the system access success rate under the premise of ensuring the high priority service delay requirements.…”
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Design of Interactive Media for Japanese M-Learning Based on Android Using UML and Waterfall Model by Apriade Voutama, Elfina Novalia

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Study of Complex Helical Drill with a “S” Type Chisel Edge Tip Orient to Carbon Fiber Reinforced Plastics by Yu He, Xiaolong Zhou, Ping Zou, Kun Liu

“…In this paper, a complex helicoids’ drill tip of “S” type chisel edge grinded with a three-parallel universal CNC grinding machine tool is carefully studied to obtain the optimum drill bit tip geometry parameters. The effects of experimental parameters, such as apex angle, chisel edge incline angle, and structure circumference rear angle, on the quality of the drilling hole and the machining force were studied from the orthogonal experiment compared with the ordinary drill bit. …”
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