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Search Results: 1 - 10 of 28811 matches for " Zhu Zhiwei "
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Cooperative Distributed Sensors for Mobile Robot Localization  [PDF]
Zhiwei Liang, Songhao Zhu
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.24046
Abstract: This paper presents a probabilistic algorithm to collaborate distributed sensors for mobile robot localization. It uses a sample-based version of Markov localization—Monte Carlo localization (MCL), capable of localizing mobile robot in an any-time fashion. During robot localization given a known environment model, MCL method is employed to update robot’s belief whichever information (positive or negative) attained from environmental sensors. Meanwhile, an implementation is presented that uses color environmental cameras for robot detection. All the parameters of each environmental camera are unknown in advance and need be calibrated independently by robot. Once calibrated, the positive and negative detection models can be built up according to the parameters of environmental cameras. A further experiment, obtained with the real robot in an indoor office environment, illustrates it has drastic improvement in global localization speed and accuracy using our algorithm.
A Novel Fractional Order Model for the Dynamic Hysteresis of Piezoelectrically Actuated Fast Tool Servo
Zhiwei Zhu,Xiaoqin Zhou
Materials , 2012, DOI: 10.3390/ma5122465
Abstract: The main contribution of this paper is the development of a linearized model for describing the dynamic hysteresis behaviors of piezoelectrically actuated fast tool servo (FTS). A linearized hysteresis force model is proposed and mathematically described by a fractional order differential equation. Combining the dynamic modeling of the FTS mechanism, a linearized fractional order dynamic hysteresis (LFDH) model for the piezoelectrically actuated FTS is established. The unique features of the LFDH model could be summarized as follows: (a) It could well describe the rate-dependent hysteresis due to its intrinsic characteristics of frequency-dependent nonlinear phase shifts and amplitude modulations; (b) The linearization scheme of the LFDH model would make it easier to implement the inverse dynamic control on piezoelectrically actuated micro-systems. To verify the effectiveness of the proposed model, a series of experiments are conducted. The toolpaths of the FTS for creating two typical micro-functional surfaces involving various harmonic components with different frequencies and amplitudes are scaled and employed as command signals for the piezoelectric actuator. The modeling errors in the steady state are less than ±2.5% within the full span range which is much smaller than certain state-of-the-art modeling methods, demonstrating the efficiency and superiority of the proposed model for modeling dynamic hysteresis effects. Moreover, it indicates that the piezoelectrically actuated micro systems would be more suitably described as a fractional order dynamic system.
Semantic Scene Segmentation for Advanced Story Retrieval
Songhao Zhu,Zhiwei Liang
Information Technology Journal , 2011,
Abstract: In this study, the issue of categorizing video scenes into semantic classifications is addressed with respect to the information of audio-visual cues. More specifically, the grammar of film production is first exploited to specify scene contents with respect to human perception. Next, each scene is categorized into one of the following three classes: conversation, action and suspense. To achieve more specific scene and consist with human perception, conversation scene are further categorized into emotional conversation and common one and action scene are categorized into gunfight, beating and chasing scene. This study is a step toward browsing and retrieval of feature films on the internet in limited bandwidth, video repository and rating of feature films of interest.
Integral homology of loop groups via Langlands dual groups
Zhiwei Yun,Xinwen Zhu
Mathematics , 2009,
Abstract: Let K be a connected compact Lie group, and G be its complexification. The homology of the based loop group \Omega K with integer coefficients is naturally a \ZZ-Hopf algebra. After possibly inverting 2 or 3, we identify H_*(\Omega K,\ZZ) with the Hopf algebra of algebraic functions on B^\vee_e, where B^\vee is a Borel subgroup of the Langlands dual group scheme G^\vee of G and B^\vee_e is the centralizer in B^\vee of a regular nilpotent element e\in\Lie B^\vee. We also give a similar interpretation for the equivariant homology of \Omega K under the maximal torus action.
Meridional seesaw-like distribution of the Meiyu rainfall over the Changjiang-Huaihe River Valley and characteristics in the anomalous climate years
XiaYing Zhu,JinHai He,ZhiWei Wu
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-0280-3
Abstract: Although Meiyu rainfall has its in-phase spatial variability over the Changjiang-Huaihe River Valley (CHRV) in most years, it is distributed in some years like a seesaw to the north and south of the Changjiang River, when the precipitation tends to be nearly normal throughout the valley, which would inevitably increase difficulties of making short-term prediction of the rainfall. For this reason, EOF analysis is made on 15 related stations’ precipitation from June to July during 1951–2004, revealing that the EOF2 mode shows largely a north-south seesaw-like pattern, and thereby classifying Meiyu patterns into two types: “northern drought and southern flood (NDSF)” and “northern flood and southern drought (NFSD)”. Afterwards, the authors investigated ocean-atmospheric characteristics when these two anomalous types occured using the NCEP reanalysis (version 1) and the extended reconstructed SSTs (version 2). The results show that in the NDSF years, the low-level frontal area and moisture convergence center lie more southward, accompanied by weaker subtropical summer monsoon over East Asia, with the western Pacific subtropical high and 200 hPa South Asia High being more southward. Both the Northern and Southern Hemisphere Annular Modes are stronger than normal in preceding February; SST is higher off China during boreal winter and spring and the opposite happens in the NFSD years. Also, this seesaw-form Meiyu rainfall distribution might be affected to some degree by the previous ENSO event.
Flexible Navigation Strategies by Predicting Human Motion Tendency
Zhiwei Liang,Songhao Zhu,Cheng Yanyun
Information Technology Journal , 2012,
Abstract: When service robots present in environments coexist with people, human-aware navigation become an important problem to be addressed. For doing so, this study designed a human-aware motion planner by inference of human motion modes in a camera network. Given a grid map of an indoor environment, human motion mode can be defined as a probabilistic form and fused into a probabilistic grid map in order to adjust robot navigation strategies. First, a two-level learning algorithm is employed to learn motion modes of persons based on collections of trajectories which are recorded by a camera network. Subsequently, a chain of Gaussian distributions are applied to describe each motion mode. Based on these modes, human motion prediction can be computed. Experimental results show the effectiveness of fusing human motion tendency to adapt robot navigation behaviors.
A 3D Isodiametric Problem with Additional Constraints
Jun Luo,Yi Yang,Zhiwei Zhu
Mathematics , 2015,
Abstract: For $\theta\in(\frac{\pi}{3},\pi)$ let $C_\theta$ be the infinite right circular cone in $\mathbb{R}^{3}$ with aperture $\theta$, which is symmetric about the $x$-axis and has its apex at the origin $O$. Among the compact convex domains $\Delta$ of diameter $1$ with $O\in\Delta\subset C_\theta$, we show that there is a unique domain $\Delta_\theta$ with maximal volume. Moreover, we give complete information on the shape of $\Delta_\theta$ and compute the volume.
Overcome the Impairment of NK Cells for Icon and Antibody Immunotherapy of Cancer  [PDF]
Zhiwei Hu
Journal of Immune Based Therapies, Vaccines and Antimicrobials (JIBTVA) , 2013, DOI: 10.4236/jibtva.2013.21001
Abstract: Natural killer (NK) cells play an important role in innate immunity and in mediating antibody and Icon (an antibody-like factor VII/IgG1 Fc immunoconjugate, which, to our best knowledge, was the first therapeutic agent for dual targeting of both the tumor cells and tumor angiogenic endothelial cells) for cancer immunotherapy. However, a common yet often neglected observation and challenge in antibody immunotherapy is that NK cells are often impaired in cancer patients. Here we hypothesize that the impairment of NK cells significantly contributes to host resistance to antibody immunotherapy for cancer. In order for antibody and Icon to achieve their optimal therapeutic efficacy, we briefly reviewed the current strategies to enhance NK activity, including infusion of cytokines, vaccines or NK cells, and the use of dietary supplements. Moreover, from our point of view we identified some remaining challenges and propose to combine these NK-enhancing strategies with Icon or antibody to overcome NK impairment and ultimately to optimize the efficacy of Icon and antibody immunotherapy for cancer.
Investigations on Inhibitors of Hedgehog Signal Pathway: A Quantitative Structure-Activity Relationship Study
Ruixin Zhu,Qi Liu,Jian Tang,Huiliang Li,Zhiwei Cao
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12053018
Abstract: The hedgehog signal pathway is an essential agent in developmental patterning, wherein the local concentration of the Hedgehog morphogens directs cellular differentiation and expansion. Furthermore, the Hedgehog pathway has been implicated in tumor/stromal interaction and cancer stem cell. Nowadays searching novel inhibitors for Hedgehog Signal Pathway is drawing much more attention by biological, chemical and pharmological scientists. In our study, a solid computational model is proposed which incorporates various statistical analysis methods to perform a Quantitative S tructure- A ctivity R elationship (QSAR) study on the inhibitors of Hedgehog signaling. The whole QSAR data contain 93 cyclopamine derivatives as well as their activities against four different cell lines (NCI-H446, BxPC-3, SW1990 and NCI-H157). Our extensive testing indicated that the binary classification model is a better choice for building the QSAR model of inhibitors of Hedgehog signaling compared with other statistical methods and the corresponding in silico analysis provides three possible ways to improve the activity of inhibitors by demethylation, methylation and hydroxylation at specific positions of the compound scaffold respectively. From these, demethylation is the best choice for inhibitor structure modifications. Our investigation also revealed that NCI-H466 served as the best cell line for testing the activities of inhibitors of Hedgehog signal pathway among others.
Comparison of Different Ranking Methods in Protein-Ligand Binding Site Prediction
Jun Gao,Qi Liu,Hong Kang,Zhiwei Cao,Ruixin Zhu
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13078752
Abstract: In recent years, although many ligand-binding site prediction methods have been developed, there has still been a great demand to improve the prediction accuracy and compare different prediction algorithms to evaluate their performances. In this work, in order to improve the performance of the protein-ligand binding site prediction method presented in our former study, a comparison of different binding site ranking lists was studied. Four kinds of properties, i.e., pocket size, distance from the protein centroid, sequence conservation and the number of hydrophobic residues, have been chosen as the corresponding ranking criterion respectively. Our studies show that the sequence conservation information helps to rank the real pockets with the most successful accuracy compared to others. At the same time, the pocket size and the distance of binding site from the protein centroid are also found to be helpful. In addition, a multi-view ranking aggregation method, which combines the information among those four properties, was further applied in our study. The results show that a better performance can be achieved by the aggregation of the complementary properties in the prediction of ligand-binding sites.
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