Deep reinforcement learning for weak human activity localization.

Human activity localization aims at recognizing contents and detecting locations of activities in video sequences. With an increasing number of untrimmed video data, traditional activity localization methods always suffer from two major limitations. First, detailed annotations are needed in most existing methods, i.e., bounding-box annotations in every frame, which are both expensive and time consuming. Second, the search space is too large for 3D activity localization, which requires generating a large number of proposals. In this paper, we propose a unified deep Q-network with weak reward and weak loss (DWRLQN) to address the two problems. Certain weak knowledge and weak constraints involving the temporal dynamics of human activity are incorporated into a deep reinforcement learning framework under sparse spatial supervision, where we assume that only a portion of frames are annotated in each video sequence. Experiments on UCF-Sports, UCF-101 and sub-JHMDB demonstrate that our proposed model achieves promising performance by only utilizing a very small number of proposals. More importantly, our DWRLQN trained with partial annotations and weak information even outperforms fully supervised methods.

A quasi-dense matching approach and its calibration application with Internet photos.

This paper proposes a quasi-dense matching approach to the automatic acquisition of camera parameters, which is required for recovering 3-D information from 2-D images. An affine transformation-based optimization model and a new matching cost function are used to acquire quasi-dense correspondences with high accuracy in each pair of views. These correspondences can be effectively detected and tracked at the sub-pixel level in multiviews with our neighboring view selection strategy. A two-layer iteration algorithm is proposed to optimize 3-D quasi-dense points and camera parameters. In the inner layer, different optimization strategies based on local photometric consistency and a global objective function are employed to optimize the 3-D quasi-dense points and camera parameters, respectively. In the outer layer, quasi-dense correspondences are resampled to guide a new estimation and optimization process of the camera parameters. We demonstrate the effectiveness of our algorithm with several experiments.

Optical fiber light source directs neurite growth.

Guiding the growth of a neurite by directing ~800 nm laser light to the leading edge of the neurite's growing region can be accomplished by controlling the position and direction in three dimensional space of a tapered optical fiber through which the light is projected. We control the position, angle and power of the laser beam to direct the growth of actin accumulations in neurites which affects their mobility.

Study on the anatase to rutile phase transformation and controlled synthesis of rutile nanocrystals with the assistance of ionic liquid.

We developed a route to synthesize rutile TiO(2) nanocrystals (NCs) with the assistance of 1-butyl-3-methylimidazolium chloride (bmim(+)Cl(-)). The phase transformation from anatase to rutile phase was investigated, and a simple model to describe the phase transformation process was proposed considering that the nucleation and growth of rutile phase were determined by the aggregation manner of anatase NCs and Ostwald ripening process, respectively. It was demonstrated that the surfactant-like nature of the IL used was crucial for controlling the crystallization process via controlling the aggregation manner of the NCs. The phase, shape, and size of TiO(2) NCs could be tuned by the controlling the operating conditions, such as temperature, solution acidity, and reactant concentration of the bmim(+)Cl(-)/TiCl(4)/H(2)O reaction system. Phase-pure rutile multipods and 1D nanorods with different sizes were controllably obtained.

Shape and size controlled synthesis of anatase nanocrystals with the assistance of ionic liquid.

We report an ionic liquid (IL) assisted hydrothermal method to synthesize anatase TiO(2) nanocrystals (NCs), in which TiCl(4) was used as precursor, 1-butyl-3-methylimidazolium chloride (bmim(+)Cl(-)) as IL, and F(-) or SO(4)(2-) ions as phase transformation inhibitor. The surfactant-like nature of IL was found to play a key role in controlling the crystallization process via controlling the aggregation manner of the NCs. The fine-tuning abilities of the operating parameters of the bmim(+)Cl(-)/TiCl(4)/H(2)O system facilitated the controlling over the shape and size of TiO(2) NCs. Phase-pure anatase monodisperse NCs with various shape and size were controllably obtained. Moreover, the aggregation manners of anatase NCs were also studied, and it was demonstrated that the high concentration of HF or H(2)SO(4) could result in aggregation of anatase NCs to form pseudo single crystals.

In-situ synthesis of noble metal nanoparticles in alginate solution and their application in catalysis.

Integration of eco-friendly method into metallic nanotechnology is one of the key issues in the field of nanoscience research. In this work, we reported a facile method to synthesize noble metal (Pt, Au, and Pd) nanoparticles in sodium alginate (SA) aqueous solution at 100 degrees C. The SA provides circumstance for reducing the metal precursors to their corresponding elemental states, and also acts as stabilizing agent for these metal nanoparticles. X-ray photoelectron spectroscopy of the as-produced metal-SA composites showed that the metallic form was the dominant species in the SA matrix under the experimental conditions. Transmission electron microscopy demonstrated that the metallic nanoparticles prepared in this way appeared to be homogeneous and their sizes were well within quantum size domain (<10 nm). The size and size distribution of the metal nanoparticles can be adjusted by altering the concentration of the metal precursors. The Pt-SA suspension could be cross-linked with divalent ions to form beads with porous structure at room temperature. The reaction behavior of cyclohexene hydrogenation suggested that the resultant Pt-alginate composites exhibited high catalytic activity.

Preparation of porous chromium oxide nanotubes using carbon nanotubes as templates and their application as an ethanol sensor.

Chromium oxide nanotubes were successfully prepared using multi-walled carbon nanotubes (MWCNTs) as a template via a supercritical fluid-mediated route. In this method, with chromium (III) nitrate nonahydrate as precursor, chromium oxide was first deposited on MWCNTs in supercritical ethanol in the presence of NH(4)HCO(3). The as-prepared chromium oxide/MWCNT nanocomposites were characterized by transmission electron microscopy, x-ray diffraction, infrared spectroscopy and thermogravimetric analysis. It was demonstrated that the MWCNTs were coated with a layer of amorphous Cr(2)O(3)·xH(2)O. The thickness of the Cr(2)O(3)·xH(2)O sheath on MWCNTs could be tuned by manipulating the ratio of precursor to MWCNTs. Calcining the composites at 550 °C, the MWCNTs were removed, producing polycrystalline α-Cr(2)O(3) nanotubes. The as-prepared α-Cr(2)O(3) sample was used as a sensor material to detect ethanol vapor, and it was demonstrated that the α-Cr(2)O(3) nanotubes exhibited good performance even at 400 °C.

Low-temperature synthesis of Mn(3)O(4) nanoparticles loaded on multi-walled carbon nanotubes and their application in electrochemical capacitors.

A low-temperature, efficient and one-step deposition method, in which Mn(CH(3)COO)(2)·4H(2)O serves as precursor and O(2) as oxidant, was employed to deposit Mn(3)O(4) nanoparticles on multi-walled carbon nanotubes (MWCNTs) in ethanol solution at 150 and 200 °C. The resulting Mn(3)O(4)/MWCNT composites were characterized by means of different techniques including x-ray diffraction, x-ray photoelectron spectroscopy and transmission electron microscopy. It was indicated that the Mn(3)O(4) nanoparticles were attached uniformly on MWCNTs with sizes less than 10 nm, and the loading amount of Mn(3)O(4) could be tuned by changing the initial weight ratio of Mn(CH(3)COO)(2)·4H(2)O/MWCNT. The electrochemical behavior of the Mn(3)O(4)/MWCNT composites was examined by cyclic voltammetry, and the result indicated the specific capacitance of the composite electrode was 330 F g(-1), nearly 18 times higher than that of the pure MWCNT electrode. The good performance of the as-prepared composites as electrode material may be attributed to the synergistic effects of the Mn(3)O(4) nanoparticles and the MWCNTs.

One-pot synthesis of ZnS/polymer composites in supercritical CO2-ethanol solution and their applications in degradation of dyes.

A facile method to decorate the polymeric hollow spheres with ZnS nanoparticles has been presented. In this method, the precursors, Zn(Ac)(2)H(2)O and CH(3)CSNH(2), were first adsorbed by the polymer substrate in supercritical CO(2)-ethanol solution at 35 degrees C. Followed by heating the mixture at 100 degrees C for 2 h, ZnS/polymer composites were obtained. The as-produced ZnS/polymer composites were characterized by means of IR spectra, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy. It was demonstrated that crystalline ZnS nanoparticles with size of 3-5 nm were uniformly decorated on the polymer spheres under suitable conditions. The resultant ZnS/polymer composites exhibited high efficiency for degrading eosin B, methyl orange and methylene blue under UV light irradiation.

Decoration carbon nanotubes with Pd and Ru nanocrystals via an inorganic reaction route in supercritical carbon dioxide-methanol solution.

This work describes a method to decorate carbon nanotubes (CNTs) with metallic Pd and Ru nanocrystals via inorganic reactions in supercritical (SC) CO2-methanol solutions. In this route, PdCl2 or RuCl3.3H2O dissolved in SC CO2-methanol solution acted as a metal precursor and CNTs functioned as a template to direct the deposition of produced nanoparticles. Methanol served as the reductant for the precursors as well as cosolvent to enhance the dissolution of precursors in SC CO2. Dry products were readily obtained through in situ extraction with SC CO2 after reactions. The products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. It was demonstrated that the loading content and particle size of the nanoparticles deposited on CNTs could be tuned by changing the weight ratio of the precursor to CNTs. This simple and efficient approach may also be utilized to synthesize other high-purity materials using inorganic salt precursors in SC CO2-based solution.

Synthesis and characterization of ZnS-montmorillonite nanocomposites and their application for degrading eosin B.

Nanocomposites of zinc sulfide (ZnS) and montmorillonite (MMT) were prepared via a hydrothermal route. In this method, the MMT treated with hexadecyltrimethyl ammonium bromide (HTAB) aqueous solution was dispersed in the aqueous solution of thiourea and Zn(OOCHCH(3))(2)2H(2)O, and heated at 170 degrees C for about 4 h, resulting in ZnS-MMT composites. The as-prepared nanocomposites were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption analysis. It was demonstrated that the interlayer space of MMT was enlarged from 0.98 to 3.77 nm after the treatment with HTAB aqueous solution, and the ZnS nanoparticles were deposited on the layers of MMT. Nitrogen sorption analysis demonstrated that the specific surface area of the samples decreased from 39.2 m(2)/g of the pristine MMT to 5.9 m(2)/g of the final ZnS-MMT composites. The resulting ZnS-MMT nanocomposites (50.0 mg) could degrade eosin B completely in aqueous solution (75 ml, 3.2x10(-5) M) within 20 min under UV irradiation.

Synthesis of polyaniline nanofibrous networks with the aid of an amphiphilic ionic liquid.

In this work, polyaniline (PANI) nanofibrous networks were prepared using ionic liquid (IL), 1-hexadecyl-3-methylimidazolium chloride (C16MIMCl), as a template through oxidative polymerization of aniline with ammonium persulfate. The resulting PANI was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis, and FTIR. It was indicated that the as-prepared PANI was in the emeraldine form and its morphology strongly depended on the molar ratio of aniline/C16MIMCI. A possible mechanism for the formation of PANI nanofibrous networks was that the ordered micro-domains of the IL acted as template to direct the growth of the nanostructures.

Replication of biological organizations through a supercritical fluid route.

A novel and simple method to replicate biological organizations (cotton and pollen grains) with high precision was proposed, in which the precursor dissolved in supercritical CO2 reacted with the surface active groups and adsorbed surface water on biological templates, followed by in situ SCF extraction of the byproducts and unreacted precursor, resulting in inorganic replicas faithfully copying both the macro- and microstructures of the biotemplates.

Pervasive computing based multimodal tele-home healthcare system.

This paper discusses a pervasive computing based multimodal tele-home healthcare system in terms of a Human-Centered Pervasive Computing System Model.