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J-Sim: a simulation and emulation environment for wireless sensor networks
Sobeih, A.,Hou, J.C.,Lu-Chuan Kung,Ning Li,Honghai Zhang,Wei-Peng Chen,Hung-Ying Tyan,Hyuk Lim IEEE 2006 IEEE wireless communications Vol.13 No.4
<P>Wireless sensor networks have gained considerable attention in the past few years. They have found application domains in battlefield communication, homeland security, pollution sensing, and traffic monitoring. As such, there has been an increasing need to define and develop simulation frameworks for carrying out high-fidelity WSN simulation. In this article we present a modeling, simulation, and emulation framework for WSNs in J-Sim - an open source, component-based compositional network simulation environment developed entirely in Java. This framework is built on the autonomous component architecture and extensible internetworking framework of J-Sim, and provides an object-oriented definition of target, sensor, and sink nodes, sensor and wireless communication channels, and physical media such as seismic channels, mobility models, and power models (both energy-producing and energy-consuming components). Application-specific models can be defined by subclassing classes in the simulation framework and customizing their behaviors. We also include in J-Sim a set of classes and mechanisms to realize network emulation. We demonstrate the use of the proposed WSN simulation framework by implementing several well-known localization, geographic routing, and directed diffusion protocols, and perform performance comparisons (in terms of the execution time incurred and memory used) in simulating WSN scenarios in J-Sim and ns-2. The simulation study indicates the WSN framework in J-Sim is much more scalable than ns-2 (especially in memory usage). We also demonstrate the use of the WSN framework in carrying out real-life full-fledged Future Combat System (FCS) simulation and emulation</P>
Characteristics of aerodynamic forces exerted on a twisted cylinder at a low Reynolds number of 100
Wei, D.J.,Yoon, H.S.,Jung, J.H. Pergamon Press ; Elsevier Science Ltd 2016 Computers & fluids Vol.136 No.-
Laminar flow over a twisted cylinder is numerically simulated at a Reynolds number of 100. The flow past a smooth cylinder is calculated for comparison. Jung and Yoon (J. Fluid Mech., 759, 2014) showed the considerable suppression of force coefficients at the subcritical Reynolds number of 3000. The present results verify that the twisted shape of the cylinder can be used to reduce the force coefficients at a low Reynolds number containing the laminar flow. This suppression of the force coefficients is supported by a longer vortex formation length produced by the twisted cylinder. We investigated the characteristics of the local force coefficients for a twisted cylinder. The simple periodic oscillation of the time histories of total and local lift coefficients for the twisted cylinder exhibits the same pattern as that of a smooth cylinder. However, the time history of drag for the twisted cylinder reveals the presence of multi-frequency oscillations, resulting in harmonic behavior of the power spectra. This is confirmed by a time sequence of the instantaneous flow fields during the half-period of the time histories of force coefficients. The nature of the three-dimensional (3-D) twisted shape forms the 3-D vortical structures along the spanwise direction, which leads to the harmonic behavior of the drag time trace power spectra.
Logarithmically completely monotonic functions and Gurland's ratio for the gamma function
Y. J. Wei,S. L. Zhang,C. P. Chen 장전수학회 2007 Advanced Studies in Contemporary Mathematics Vol.15 No.2
Two logarithmically completely monotonic functions involving gamma function are proved. As an application, bounds for the ratio T(x;y) = ( x)(y)= 2((x+y)=2) is established and the corresponding result by J. D. keckic and P. M.Vasic is refined.
Response of plasma rotation to resonant magnetic perturbations in J-TEXT tokamak
Yan, W,Chen, Z Y,Huang, D W,Hu, Q M,Shi, Y J,Ding, Y H,Cheng, Z F,Yang, Z J,Pan, X M,Lee, S G,Tong, R H,Wei, Y N,Dong, Y B IOP 2018 Plasma physics and controlled fusion Vol.60 No.3
<P>The response of plasma toroidal rotation to the external resonant magnetic perturbations (RMP) has been investigated in Joint Texas Experimental Tokamak (J-TEXT) ohmic heating plasmas. For the J-TEXT’s plasmas without the application of RMP, the core toroidal rotation is in the counter-current direction while the edge rotation is near zero or slightly in the co-current direction. Both static RMP experiments and rotating RMP experiments have been applied to investigate the plasma toroidal rotation. The core toroidal rotation decreases to lower level with static RMP. At the same time, the edge rotation can spin to more than 20 km s<SUP>−1</SUP> in co-current direction. On the other hand, the core plasma rotation can be slowed down or be accelerated with the rotating RMP. When the rotating RMP frequency is higher than mode frequency, the plasma rotation can be accelerated to the rotating RMP frequency. The plasma confinement is improved with high frequency rotating RMP. The plasma rotation is decelerated to the rotating RMP frequency when the rotating RMP frequency is lower than the mode frequency. The plasma confinement also degrades with low frequency rotating RMP.</P>
Dual NURBS Path Smoothing for 5-Axis Linear Path of Flank Milling
Dongdong Li,Weimin Zhang,Wei Zhou,Tengfei Shang,Jürgen Fleischer 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.12
Linear path is still widely used to describe the five-axis machining trajectory. Five-axis tool path consists of two parts, one trajectory describes the tool tip position, and the other one represents the second point on tool axis to define the tool orientation. The natural disadvantages of G01 path are tangential and curvature discontinuities at freeform surface, which will lead to feedrate fluctuation and accuracy decrease due to the drive constraints of machine tool. In this study, a path smoothing method is proposed to smooth and optimize the linear path by using dual NURBS curves. Firstly, according to the accuracy requirements, the tool tip spline can be fitted. Secondly, the tool orientation spline can also be obtained by a coordinate system mapping method. Then, the synchronization equation of the two spline parameters is established to achieve interpolation synchronization of cutter location points. Finally, the smoothing dual NURBS tool path can be obtained with continuous curvature to improve the surface quality, motion stability and machining efficiency. Simulations and experiments validate its practicability and reliability. This method is no need to upgrade the CAM, and also could be integrated into CAM system to perform the 5-axis path smoothing.
Fenglan Sun,Mingyan Tuo,Jürgen Kurths,Wei Zhu 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.8
This paper studies the finite-time consensus of leader-following multi-agent systems with multiple time delays over time-varying topology. The finite-time consensus protocol based on the agents’ states and the communication topology is designed. By adopting the algebraic graph theory, Lyapunov stability theory and pinning control method, some sufficient conditions for the finite-time consensus are given. It is proved that the system can reach consensus in a finite time both over the connected and disconnected topology. Moreover, the upper bound of the convergence time is given. Several simulations are presented to verify the effectiveness of the adopted method.
Fyn promotes proliferation, differentiation, survival and function of osteoclast lineage cells
Kim, Hyun‐,Ju,Warren, Julia T.,Kim, Shin‐,Yoon,Chappel, Jean C.,DeSelm, Carl J.,Ross, F. Patrick,Zou, Wei,Teitelbaum, Steven L. Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of cellular biochemistry Vol.111 No.5
<P><B>Abstract</B></P><P>c‐Src and Lyn are the only Src family kinases (SFKs) with established activity in osteoclasts (OCs). c‐Src promotes function via cytoskeletal organization of the mature resorptive cell while Lyn is a negative regulator of osteoclastogenesis. We establish that Fyn, another SFK, also impacts the OC, but in a manner distinctly different than c‐Src and Lyn. Fyn deficiency principally alters cells throughout the osteoclastogenic process, resulting in diminished numbers of resorptive polykaryons. Arrested OC formation in the face of insufficient Fyn reflects reduced proliferation of precursors, in response to M‐CSF and retarded RANK ligand (RANKL)‐induced differentiation, attended by suppressed activation of the osteoclastogenic signaling molecules, c‐Jun, and NF‐κB. The anti‐apoptotic properties of RANKL are also compromised in cells deleted of Fyn, an event mediated by increased Bim expression and failed activation of Akt. The defective osteoclastogenesis of Fyn−/− OCs dampens bone resorption, in vitro. Finally, while Fyn deficiency does not regulate basal osteoclastogenesis, in vivo, it reduces that stimulated by RANKL by ∼2/3. Thus, Fyn is a pro‐resorptive SFK, which exerts its effects by prompting proliferation and differentiation while attenuating apoptosis of OC lineage cells. J. Cell. Biochem. 111: 1107–1113, 2010. © 2010 Wiley‐Liss, Inc.</P>
China Spallation Neutron Source: Accelerator Design Iterations and R&D Status
J. Wei,C.-D. Deng,C.-H. Wang,C.-T. Shi,H. Sun,H.-F. Ouyang,H.-M. Qu,H.-Y. Dong,J. Li,J. Zhang,J.-S. Cao,J.-Y. Tang,L. Dong,L.-L. Wang,Q. Qin,Q.-B. Wang,S. Wang,S.-N. Fu,S.-X Fang,T. -G. Xu,W. Kang,Y.- 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I
The China Spallation Neutron Source (CSNS) is a high-power, accelerator-based project currently under preparation. The accelerator complex consists of an H$^-$ ion source, an H$^-$ linac, a rapid-cycling proton synchrotron, and the transport lines. During the past year, the design of most accelerator systems went through major iterations, and initial research and developments was started on the prototyping of several key components.
Wei, J.,Wu, Y.,Cho, L. H.,Yoon, J.,Choi, H.,Yoon, H.,Jin, P.,Yi, J.,Lee, Y. S.,Jeong, H. J. Botanical Society of Korea 2017 Journal of plant biology Vol.60 No.3
<P>T-DNA tagging lines are useful for analyzing the functions of genes and regulatory elements. We have previously generated approximately 100,000 insertional mutants in japonica rice (Oryza sativa), using T-DNA vectors carrying the promoter-less GUS reporter gene. In this study, we conducted GUS assays of seedlings from 430 lines in which T-DNA was inserted into transcription factor genes. Among the 75 lines that showed GUS signals, nine displayed an endosperm-preferential expression pattern; two lines demonstrated GUS signals in both endosperm and roots; 21 lines had GUS expression mainly in leaves; 19 lines showed GUS signal in both leaves and roots; and 24 lines expressed GUS predominantly in the roots. Co-segregation analyses of 49 homozygous lines indicated that the GUS expression patterns observed from 38 lines were due to the T-DNA insertion. We also identified fusion transcripts between tagged genes and the GUS reporter in six lines. Quantitative RT-PCR confirmed that the GUS expression patterns of those tagged lines indeed represent organ-and tissue-preferential expression of the tagged genes. The GUS-tagged transcription factor lines identified here will be useful for functional analysis of these candidates.</P>