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Search Results: 1 - 10 of 23684 matches for " Zhiwei Liang "
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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.
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.
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.
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.
Improved Monte Carlo Localization Algorithm in a Hybrid Robot and Camera Network
Zhiwei Liang,Xudong Ma,Fang Fang,Songhao Zhu
Information Technology Journal , 2010,
Abstract: In order to overcome the difficulty of a mobile robot to perform localization only with its onboard sensors, this study presents a probabilistic algorithm Monte Carlo Localization (MCL) to solve the problem of mobile robot localization in a hybrid robot and camera network in real time. On one hand, the robot does perform localization depending on its laser sensor using Monte Carlo method. On the other hand, environment cameras can detect the robot in their field of view during robot localization. According to a built environment camera model, MCL method extended to update robot’s belief whichever information (positive or negative) attained from environmental camera sensors. Meanwhile, 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.
Thematic and Spatial Resolutions Affect Model-Based Predictions of Tree Species Distribution
Yu Liang, Hong S. He, Jacob S. Fraser, ZhiWei Wu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0067889
Abstract: Subjective decisions of thematic and spatial resolutions in characterizing environmental heterogeneity may affect the characterizations of spatial pattern and the simulation of occurrence and rate of ecological processes, and in turn, model-based tree species distribution. Thus, this study quantified the importance of thematic and spatial resolutions, and their interaction in predictions of tree species distribution (quantified by species abundance). We investigated how model-predicted species abundances changed and whether tree species with different ecological traits (e.g., seed dispersal distance, competitive capacity) had different responses to varying thematic and spatial resolutions. We used the LANDIS forest landscape model to predict tree species distribution at the landscape scale and designed a series of scenarios with different thematic (different numbers of land types) and spatial resolutions combinations, and then statistically examined the differences of species abundance among these scenarios. Results showed that both thematic and spatial resolutions affected model-based predictions of species distribution, but thematic resolution had a greater effect. Species ecological traits affected the predictions. For species with moderate dispersal distance and relatively abundant seed sources, predicted abundance increased as thematic resolution increased. However, for species with long seeding distance or high shade tolerance, thematic resolution had an inverse effect on predicted abundance. When seed sources and dispersal distance were not limiting, the predicted species abundance increased with spatial resolution and vice versa. Results from this study may provide insights into the choice of thematic and spatial resolutions for model-based predictions of tree species distribution.
Performance Benefits of DataMPI: A Case Study with BigDataBench
Fan Liang,Chen Feng,Xiaoyi Lu,Zhiwei Xu
Computer Science , 2014,
Abstract: Apache Hadoop and Spark are gaining prominence in Big Data processing and analytics. Both of them are widely deployed on Internet companies. On the other hand, high-performance data analysis requirements are causing academical and industrial communities to adopt state-of-the-art technologies in HPC to solve Big Data problems. Recently, we have proposed a key-value pair based communication library, DataMPI, which is extending MPI to support Hadoop/Spark-like Big Data Computing jobs. In this paper, we use BigDataBench, a Big Data benchmark suite, to do comprehensive studies on performance and resource utilization characterizations of Hadoop, Spark and DataMPI. From our experiments, we observe that the job execution time of DataMPI has up to 55% and 39% speedups compared with those of Hadoop and Spark, respectively. Most of the benefits come from the high-efficiency communication mechanisms in DataMPI. We also notice that the resource (CPU, memory, disk and network I/O) utilizations of DataMPI are also more efficient than those of the other two frameworks.
Coagulation efficiency and flocs characteristics of recycling sludge during treatment of low temperature and micro-polluted water
Zhiwei Zhou,Yanling Yang,Xing Li,Wei Gao,Heng Liang,Guibai Li,
Zhiwei Zhou
,Yanling Yang,Xing Li,Wei Gao,Heng Liang,Guibai Li

环境科学学报(英文版) , 2012,
Abstract: Drinking water treatment sludge, characterized as accumulated suspended solids and organic and inorganic matter, is produced in large quantities during the coagulation process. The proper disposal, regeneration or reuse of sludge is, therefore, a significant environmental issue. Reused sludge at low temperatures is an alternative method to enhance traditional coagulation efficiency. In the present study, the recycling mass of mixed sludge and properties of raw water (such as pH and turbidity) were systematically investigated to optimize coagulation efficiency. We determined that the appropriate dosage of mixed sludge was 60 mL/L, effective initial turbidity ranges were below 45.0 NTU, and optimal pH for DOMs and turbidity removal was 6.5--7.0 and 8.0, respectively. Furthermore, by comparing the flocs characteristics with and without recycling sludge, we found that floc structures with sludge were more irregular with average size growth to 64.7 μupm from 48.1 μupm. Recycling sludge was a feasible and successful method for enhancing pollutants removal, and the more irregular flocs structure after recycling might be caused by breakage of reused flocs and incorporation of powdered activated carbon into larger flocs structure. Applied during the coagulation process, recycling sludge could be significant for the treatment of low temperature and micro-polluted source water.
BmK-YA, an Enkephalin-Like Peptide in Scorpion Venom
Yan Zhang, Junyan Xu, Zhiwei Wang, Xiuli Zhang, Xinmiao Liang, Olivier Civelli
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040417
Abstract: By screening extracts of venom from the Asian scorpion Buthus martensii Karsch (BmK) for their abilities to activate opioid receptors, we have identified BmK-YA, an amidated peptide containing an enkephalin-like sequence. BmK-YA is encoded by a precursor that displays a signal sequence and contains four copies of BmK-YA sequences and four of His4-BmK-YA, all flanked by single amino acid residues. BmK-YA and His4-BmK-YA are amidated and thus fulfill the characteristics expected of bioactive peptides. BmK-YA can activate mammalian opioid receptors with selectivity for the δ subtype while His4-BmK-YA is inactive at opioid receptors. The discovery of BmK-YA suggests that scorpion venom may represent a novel source of bioactive molecules targeting G protein-coupled receptors (GPCRs) and reveal additional insights on the evolution of the opioid precursors.
Comparing Effects of Climate Warming, Fire, and Timber Harvesting on a Boreal Forest Landscape in Northeastern China
Xiaona Li, Hong S. He, Zhiwei Wu, Yu Liang, Jeffrey E. Schneiderman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0059747
Abstract: Forest management under a changing climate requires assessing the effects of climate warming and disturbance on the composition, age structure, and spatial patterns of tree species. We investigated these effects on a boreal forest in northeastern China using a factorial experimental design and simulation modeling. We used a spatially explicit forest landscape model (LANDIS) to evaluate the effects of three independent variables: climate (current and expected future), fire regime (current and increased fire), and timber harvesting (no harvest and legal harvest). Simulations indicate that this forested landscape would be significantly impacted under a changing climate. Climate warming would significantly increase the abundance of most trees, especially broadleaf species (aspen, poplar, and willow). However, climate warming would have less impact on the abundance of conifers, diversity of forest age structure, and variation in spatial landscape structure than burning and harvesting. Burning was the predominant influence in the abundance of conifers except larch and the abundance of trees in mid-stage. Harvesting impacts were greatest for the abundance of larch and birch, and the abundance of trees during establishment stage (1–40 years), early stage (41–80 years) and old- growth stage (>180 years). Disturbance by timber harvesting and burning may significantly alter forest ecosystem dynamics by increasing forest fragmentation and decreasing forest diversity. Results from the simulations provide insight into the long term management of this boreal forest.
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