On The Redesign of Continuous Approximation in Sliding Mode Control

Ming Wu,Jian-Shiang Chen 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10

A redesign of continuous approximation is proposed in this article. For the redesign, a smooth saturation had been formulated by four axioms and an illustrative sine saturation that satisfied the four axioms is thus formulated and applies to a sliding mode controller. The generalized sliding mode with boundary layer can provide SMC with significantly reduced chatters but with the price of robustness. Through the redesign the robustness can be improved and chatter can be alleviated as well. Simulation results on a wheeled-vehicle have shown its efficiency further.

NUMERICAL SIMULATION OF TRANSONIC SEPARATED FLOW OVER A HEMISPHERE CYLINDER AT MODERATE ANGLE OF ATTACK

An Ming Wu,Zuu Chang Hong,Cheng Sheng Wang 대한기계학회 1992 International Conference on Fluid Machinery Vol.1 No.1

A structural VAR approach to the log-linear model : Evidence of regional stock markets

Ming Wu,Kiyool Ohk,Kwangsoo Ko 한국재무학회 2018 한국재무학회 학술대회 Vol.2018 No.05

We develop a log-linear structural VAR model to decompose unexpected excess market returns into permanent and temporary cash-flow news, discount-rate news, and nonfundamental news. We make some important findings. First, contrary to recent evidence for the United States, we find that discount-rate news plays a more important role than cash-flow news in global stock markets. Second, non-fundamental factor (i.e., investor sentiment) also plays a role in developed regional stock markets outside the United States. Finally, risk premiums are significantly higher in a down market than in an up market.

Are Cash-Flow betas Really Bad?

Ming Wu,Kiyool Ohk,Kwangsoo Ko 한국재무학회 2017 한국재무학회 학술대회 Vol.2017 No.05

This study evaluates the relative importance of cash-flow news and discount-rate news based on the log-linear model for pan-Chinese stock markets (i.e., China, Hong Kong, and Taiwan). Although they belong to the same cultural region, they have different capital market regulations and practices. In this context, we find that the discount-rate beta is bad in Hong Kong and Taiwan, while the cash-flow beta is bad in China. These findings are consistent with each market’s ownership structure, dividend policy, and tax system. However, as in the U.S., risk premiums are significantly higher in down markets than in up markets.

Privacy-preserving Outsourcing Schemes of Modular Exponentiations Using Single Untrusted Cloud Server

( Ling Zhao ),( Mingwu Zhang ),( Hua Shen ),( Yudi Zhang ),( Jian Shen ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.2

Outsourcing computation is one of the most important applications in cloud computing, and it has a huge ability to satisfy the demand of data centers. Modular exponentiation computation, broadly used in the cryptographic protocols, has been recognized as one of the most time-consuming calculation operations in cryptosystems. Previously, modular exponentiations can be securely outsourced by using two untrusted cloud servers. In this paper, we present two practical and secure outsourcing modular exponentiations schemes that support only one untrusted cloud server. Explicitly, we make the base and the index blind by putting them into a matrix before send to the cloud server. Our schemes provide better performance in higher efficiency and flexible checkability which support single cloud server. Additionally, there exists another advantage of our schemes that the schemes are proved to be secure and effective without any cryptographic assumptions.

A Computational Model of Water Migration in a Closed System of Unsaturated Expansive Clay

Qiuyan Liu,Mingwu Wang,Daguo Wu,Fengqiang Shen 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

Expansive clay behaves like mechanical performances of multi-fissures, and deterioration with the changing moisture. To ensure the safe operation of foundation, the effects of intensive water migration on earth constructions founded on semiarid area, have therefore been received much more attention together with the global warming and climate changes. Herein, analytical models considering respectively liquid water and water vapor migration were presented to address changes in moisture content of unsaturated expansive clay under various water content gradients. Moreover, measured data obtained from migration experiments performed under various water content gradients in a closed system, were utilized to check the validity of analytical equations. Results indicate that the migration of both water vapor and mixed water shows nonlinear relationships with time and location. For the expansive clay with low moisture content, major components of migration water was water vapor, which accounted for 83.61 − 88.62%; while for the clay with higher water content, the liquid water was dominant migration of water due to more free water around the soil particles. The proposed model is helpful to investigate moisture migration law in the unsaturated expansive clay.

Design and analysis of integrated-circuit package antenna (ICPA) for dual-band wireless transceivers

Tong, Ming-Sze,Yang, Mingwu,Cao, Qunsheng,Kim, Hyeong-Seok,Lu, Yilong,Chen, Yinchao,Chang, Tae-Gyu Wiley Subscription Services, Inc., A Wiley Company 2006 International journal of RF and microwave computer Vol.16 No.3

<P>This article presents study of a dual-band integrated-circuit package antenna (ICPA), which operates concurrently on dual bands at 2.4 and 5.25 GHz. The antenna is designed and printed on the top surface of an IC package and fed by a single coaxial line, while the transceiver is implemented on the opposite side of the package, through the separation of a common ground plate. This “cavity-down” arrangement minimizes the electromagnetic interference between the antenna and transceiver, and satisfies the miniaturization of the design. The study consists of numerical computations, which are performed through an in-house computer solver based on the nonuniform finite-difference time-domain (NU-FDTD) method and experimental measurements. Together with the data computed using the high-frequency structure simulator (HFSS) software, the results show excellent agreement between the numerical and experimental data, and the proposed structure is deemed as a useful application in the area of highly integrated wireless transceivers. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.</P>

VM Allocation in Data Center Subject to CPU Percentile Constraints

Yue Han,Harry Perros,Mingwu Yao 한국통신학회 2020 한국통신학회 APNOMS Vol.2020 No.09

At existing cloud computing environment, virtual machine allocation mechanisms have been actively applied to resources management for processing dynamic workload in largescale data center. In this paper, we address the problem of how many virtual machines should be allocated to a server, so that a given percentile of the execution time of a job is bounded by a predefined value. We first consider the case of “dedicated CPU”, whereby we calculate the CPU allocated to a single VM. Subsequently, we extend the analysis to the case where the CPU is shared equally by different groups of VMs. In this case, we calculate how many VMs need to be allocated in each group.

A fast construction sequential analysis strategy for tall buildings

Chen, Pu,Li, Hao,Sun, Shuli,Yuan, Mingwu Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.23 No.6

In structural analysis of tall buildings the traditional primary loading analysis approach that assumes all the loads are simultaneously applied to the fully built structure has been shown to be unsuitable by many researches. The construction sequential analysis that reflects the fact of the level-by-level construction of tall buildings can provide more reliable results and has been used more and more. However, too much computational cost has prevented the construction sequential analysis from its application in CAD/CAE software for building structures, since such an approach needs to deal with systematic changing of resultant stiffness matrices following level-by-level construction. This paper firstly analyzes the characteristics of assembling and triangular factorization of the stiffness matrix in the finite element model of the construction sequential analysis, then presents a fast construction sequential analysis strategy and a corresponding step-by-step active column solver by means of improving the existing skyline solver. The new strategy avoids considerably repeated calculation by only working on the latest appended and modified part of resultant stiffness matrices in each construction level. Without any simplification, the strategy guarantees accuracy while efficiency is greatly enhanced. The numerical tests show that the proposed strategy can be implemented with high efficiency in practical engineering design.

Secure and Fine-grained Electricity Consumption Aggregation Scheme for Smart Grid

( Gang Shen ),( Yixin Su ),( Danhong Zhang ),( Huajun Zhang ),( Binyu Xiong ),( Mingwu Zhang ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.4

Currently, many of schemes for smart grid data aggregation are based on a one-level gateway (GW) topology. Since the data aggregation granularity in this topology is too single, the control center (CC) is unable to obtain more fine-grained data aggregation results for better monitoring smart grid. To improve this issue, Shen et al. propose an efficient privacy-preserving cube-data aggregation scheme in which the system model consists of two-level GW. However, a risk exists in their scheme that attacker could forge the signature by using leaked signing keys. In this paper, we propose a secure and fine-grained electricity consumption aggregation scheme for smart grid, which employs the homomorphic encryption to implement privacy-preserving aggregation of users’ electricity consumption in the two-level GW smart grid. In our scheme, CC can achieve a flexible electricity regulation by obtaining data aggregation results of various granularities. In addition, our scheme uses the forward-secure signature with backward-secure detection (FSBD) technique to ensure the forward-backward secrecy of the signing keys. Security analysis and experimental results demonstrate that the proposed scheme can achieve forward-backward security of user’s electricity consumption signature. Compared with related schemes, our scheme is more secure and efficient.