Random weighting M-estimation for linear errors-in-variables models

Xiaohan Yang,Rong Jiang,Wei-Min Qian 한국통계학회 2012 Journal of the Korean Statistical Society Vol.41 No.4

In this paper, we extend the random weighting method to linear errors-in-variables models and propose random weighting M-estimators (RWME) for parameters. Its large sample properties are studied and the consistency and asymptotic normality are proved under mild conditions. In addition, the results facilitate the construction of confidence regions and hypothesis testing for the unknown parameters. Extensive simulations are reported,showing that the proposed method works well in practical settings. The proposed methods are also applied to a data set from an AIDS clinical trial group study.

Analysis of Security Policy in Practical Internet Coordinates

Xiaohan Zhao,Xiaoxiao Song,Xiao Wang,Yang Chen,Beixing Deng,Xing Li 보안공학연구지원센터 2009 International Journal of Security and Its Applicat Vol.3 No.1

Network Coordinate (NC) System is an effective mechanism to predict network delay with limited measure overhead. As one of the representative NC systems, Practical Internet Coordinates (PIC) has proposed a security policy based on triangle inequality to defend malicious nodes in the system. However, there is a natural phenomena that nodes may violate triangle inequality in Internet. Thus, the performance of PIC security policy is worthy to be well researched under different attacks. In this paper, we analyze the security policy in PIC in three real network delay data sets and compare PIC with security to without security under four typical attacks. The experimental results in this paper demonstrate that PIC is vulnerable to attacks while more TIVs will cause higher relative error of PIC. Moreover, under attacks by more than 40% malicious nodes, the performance of PIC with security policy could barely be better than PIC without security. Even Colluding Isolate attack will result in worse performance in PIC having security policy.

Secure and Lightweight Authentication Protocol in Internet of Things

Yanlong Yang,Mengzhu Lu,Xiaohan Niu 한국멀티미디어학회 2023 The journal of multimedia information system Vol.10 No.3

The further development of Internet of things (IoT) makes the number of various terminal devices grow rapidly. At the same time, the amount of data collected and transmitted through terminal devices is also increasing. However, in the communication between devices and servers, most of them lack efficient identity authentication and encrypted communication mechanisms suitable for IoT environment. Therefore, in order to secure the communication between these devices and servers, they need to be protected by password technology. This paper proposes a secure communication protocol based on chaotic mapping algorithm, which is used to ensure the bidirectional identity authentication and data encryption between IoT devices and servers. The protocol is proved by Burrows Abadi Needham(BAN) logic, Scyther and informal security analysis that it satisfies the security and can resist various security attacks, and achieve anonymity and non-traceability. Finally, the performance comparison analysis with similar protocols shows that the proposed protocol significantly improves the security and has high efficiency.

Capacitors Energy Strategy Based Cascaded H-Bridge Converter for DC Port Failures

Xu Peng,Xiaohan Liu,Guolong Yang,Xijun Liu,Lixia Gao,Xinyu Zhu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

In this paper, a capacitors energy strategy based Cascaded H-bridge Converter (CHBC) for steady DC link voltage is proposed, which allow the CHBC to work while DC power fails. The topology of the CHBC is analyzed to construct the proposed strategy. The capacitors energy strategy is deduced based on the principle that the DC link voltage should be steady, the switch state should be smooth and the switch frequency should be normal. Experiments based on a three-module prototype, including static experiment, start experiment and step change experiment, proves the correctness of the strategy. They also verified the excellent fault tolerance ability and good dynamic performance of the proposed strategy.

Random weighting M-estimation for linear errors-in-variables models

Jiang, Rong,Yang, Xiaohan,Qian, Weimin 한국통계학회 2012 Journal of the Korean Statistical Society Vol.41 No.4

In this paper, we extend the random weighting method to linear errors-in-variables models and propose random weighting M-estimators (RWME) for parameters. Its large sample properties are studied and the consistency and asymptotic normality are proved under mild conditions. In addition, the results facilitate the construction of confidence regions and hypothesis testing for the unknown parameters. Extensive simulations are reported, showing that the proposed method works well in practical settings. The proposed methods are also applied to a data set from an AIDS clinical trial group study.

Capacitors Energy Strategy Based Cascaded H-Bridge Converter for DC Port Failures

Peng, Xu,Liu, Xiaohan,Yang, Guolong,Liu, Xijun,Gao, Lixia,Zhu, Xinyu The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

In this paper, a capacitors energy strategy based Cascaded H-bridge Converter (CHBC) for steady DC link voltage is proposed, which allow the CHBC to work while DC power fails. The topology of the CHBC is analyzed to construct the proposed strategy. The capacitors energy strategy is deduced based on the principle that the DC link voltage should be steady, the switch state should be smooth and the switch frequency should be normal. Experiments based on a three-module prototype, including static experiment, start experiment and step change experiment, proves the correctness of the strategy. They also verified the excellent fault tolerance ability and good dynamic performance of the proposed strategy.

Internal filament modulation in low-dielectric gap design for built-in selector-less resistive switching memory application

Chen, Ying-Chen,Lin, Chih-Yang,Huang, Hui-Chun,Kim, Sungjun,Fowler, Burt,Chang, Yao-Feng,Wu, Xiaohan,Xu, Gaobo,Chang, Ting-Chang,Lee, Jack C IOP 2018 Journal of Physics. D, Applied Physics Vol.51 No.5

<P>Sneak path current is a severe hindrance for the application of high-density resistive random-access memory (RRAM) array designs. In this work, we demonstrate nonlinear (NL) resistive switching characteristics of a HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB>-based stacking structure as a realization for selector-less RRAM devices. The NL characteristic was obtained and designed by optimizing the internal filament location with a low effective dielectric constant in the HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB> structure. The stacking HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB>-based RRAM device as the one-resistor-only memory cell is applicable without needing an additional selector device to solve the sneak path issue with a switching voltage of ~1 V, which is desirable for low-power operating in built-in nonlinearity crossbar array configurations.</P>

Voltage balance evaluation strategy for DC-port faults in centralized aircraft ground power unit based on three-level neutral point clamped cascaded converter

Peng, Xu,Yu, Le,Gong, Kaiyue,Liu, Xiaohan,Yang, Guolong,Xu, Jiangjun,Zhou, Chao,Gao, Lixia,Zhu, Xinyu The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.8

An aircraft ground power unit (GPU) can replace the auxiliary power unit (APU) in an aircraft while the aircraft is parked at an airport. Therefore, the problems associated with the oil consumption and air pollution of the APU are solved. However, the GPU is faced with challenges in terms of utilization, power quality, and fault tolerance. Thus, a novel centralized aircraft GPU based on a three-level neutral point clamped cascaded converter (3LNPC-CC) is introduced in this paper to improve utilization and power quality. Furthermore, an evaluation voltage balance strategy is proposed for the DC-port fault tolerance of the 3LNPC-CC. In addition, both the modulation of the phase shift pulse width modulation (PSPWM) and the control of the double closed loop are used in the 3LNPC-CC. A simulation platform including the control, modulation, and fault tolerance of the system is established to verify the feasibility and performance of the proposed GPU. In particular, it is used to evaluate the voltage balance strategy for DC-port faults. Moreover, a prototype of the GPU and relevant experiments are completed to verify the correctness and feasibility of the system and the strategy.

DEM numerical study on mechanical behaviour of coal with different water distribution models

Lihai Tan,Xin Cai,Ting Ren,Xiaohan Yang,Yichao Rui 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.5

The mechanical behaviour and stability of coal mining engineering underground is significantly affected by ground water. In this study, nuclear magnetic resonance imaging (NMRI) technique was employed to determine the water distribution characteristics in coal specimens during saturation process, based on which the functional rule for water distribution was proposed. Then, using discrete element method (DEM), an innovative numerical modelling method was developed to simulate water-weakening effect on coal behaviour considering moisture content and water distribution. Three water distribution numerical models, namely surface-wetting model, core-wetting model and uniform-wetting model, were established to explore the water distribution influences. The feasibility and validity of the surface-wetting model were further demonstrated by comparing the simulation results with laboratory results. The investigation reveals that coal mechanical properties are affected by both water saturation coefficient and water distribution condition. For all water distribution models, micro-cracks always initiate and nucleate in the water-rich area and thus lead to distinct macro fracture characteristics. With the increase of water saturation coefficient, the failure of coal tends to be less violent with less cracks and ejected fragments. In addition, the corewetting specimen is more sensitive to water than specimens with other water distribution models.

Lowest Instrumented Vertebra at L3 Versus L4 in Posterior Fusion for Moderate Lenke 5C Type Adolescent Idiopathic Scoliosis: A Case-Match Radiological Study

Zhiyi Li,You Du,Yiwei Zhao,Guanfeng Lin,Haoran Zhang,Chenkai Li,Xiaohan Ye,Yang Yang,Shengru Wang,Jianguo Zhang 대한척추신경외과학회 2023 Neurospine Vol.20 No.4

Objective: To compare the radiological outcomes in Lenke 5C type patients whose lowest instrumented vertebra (LIV) was L3 or L4 in a case-match study. Methods: We conducted a retrospective case-match study and included 82 patients in the study. Radiological results before surgery, after surgery, and at last follow-up were recorded and analyzed in the L3 and L4 groups. Results: After matching the age, Risser’s sign, sex, and main Cobb, 41 pairs of patients were enrolled in our study. The total fusion segments in the L3 group (median [interquartile range]: 5.0 [6.0–5.0]) were shorter than those in the L4 group (6.0 [6.5–6.0]). The main curve was significantly corrected after surgery in both groups, and was comparable at the last followup between groups. In addition, according to the results of Fisher precision probability test, there was no significant difference of coronal or sagittal imbalance between the 2 groups at the 2-year follow-up. Conclusion: The correction in coronal and sagittal planes in L3 group and L4 group remains similar. On account of more motion segments, L3 could be an ideal choice as LIV in moderate Lenke 5C type AIS. Long-term follow-up is needed to evaluate the effect of larger compensatory lumbar-sacral curve when stopping at L3.