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Since smart phones are always equipped with both cellular and Wi-Fi interfaces, this paper exploits the feasibility of the Wi-Fi based Device-to-Device (D2D) offloading mechanism to reduce cellular traffic. In our group LBS scenario, a group of users travel outdoors together and utilize their smart phones to form a mobile converged network, which is composed of cellular and Wi-Fi networks, to download and share the neighboring LBS data. Due to the wide-range coverage of the cellular network and the keeping-moving characteristic of users, one of these smart phones is selected to play the role of mobile proxy to download the shared LBS data using its cellular interface and then disseminate to other members using multicast over the Wi-Fi network, in which one adaptive FEC mechanism is adopted to tackle the packet loss situation. Besides, a user-transparent Machine-toMachine (M2M) based mobile proxy handoff mechanism is devised such that each smart phone can play the role of mobile proxy alternately to evenly consume each smart phone's power and thus extend the service time of the group LBS scenario. That is, the proposed offloading mechanism not only offloads the cellular network traffic but also reduces the power consumption.

This paper presents an optical force driven nano-machined actuator and the "pull-back" effect of a free-standing arc in an opto-mechanical ring resonator system. This nano-actuator obtains a maximal central displacement of 43.1 nm, with an actuation resolution of 0.28 nm, via tuning the wavelength of the control light at a fixed optical power of 2.8 mW. The "pull-back" effect occurs at the maximal displacement position, which is studied by the combination of experiments and simulation. Potential applications include bio-nano-motor, all-optical switches and opto-mechanical memories.

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Herein, the direct morphological evidence of the extension‐induced phase‐separated structures in the electrospinning jet observed by high‐speed video imaging and by light scattering technique is reported. Model solutions of poly(vinyl alcohol) (PVA)/water are electrospun. Two types of internal structures, that is, long strings and short ellipsoids, are found. A light scattering model is derived for the Vv scattering configuration to account for the scattered intensities contributed from the liquid jet itself and those from the internal structures. For the severely stretching jet of PVA/water, the Vv intensity profile is dominant by the internal structures to mask the scattering contribution from the jet itself. Moreover, the Hv intensity profile reflects the anisotropy of the oriented chains parallel to the jet axis. For the 7 wt% solution, the derived extension rate in the vicinity of the Taylor cone apex is about 3420 s−1, which is higher than the Rouse relaxation rate measured by rheometer. It is concluded that extension‐induced phase separation of the single‐phase PVA solution is likely to occur in Taylor‐cone apex to trigger the self‐assembly process for producing strings (and/or bulges) in the flowing jet, which eventually transform to become the nanofibers, after solvent removal, to be collected on the grounded collector.

In their original forms, carbon nanotubes (CNT) are spatially entangled. To make CNT papers (CNTPs), the CNT agglomerates must be dispersed and re‐entangled into a planar sheet. The processing characteristics are very different from those of traditional buck‐form nanocomposites. This article examines the processing, micro‐structures, and failure behavior of the CNTP composites. The CNTPs were first made by a dispersion and filtering process. Then, an epoxy resin was added into the CNTP by using a vacuum bag method. Different CNT weights were employed to make the CNTPs with different thicknesses and areal weights. The CNTP allows direct resin impregnation along the thickness direction and avoids the difficulty of dispersing CNTs in the viscous resin. The CNT content can be much higher than that attainable in traditional bulk CNT composites. Both tensile and tearing tests were conducted, and the fracture behaviors were examined. POLYM. COMPOS., 37:1564–1571, 2016. © 2014 Society of Plastics Engineers

Magnetite nanoparticles have been synthesized by thermal decomposition of hematite (Fe2O3) powder in the presence of high boiling point solvent. The mixture of hematite and 1- octadecene solvent was heated and stirred in nitrogen gas at the temperature of 320 °C for the desired time (∼2 to 28 hrs). The influence of the reaction time on transformation process was analyzed with X-ray diffraction (XRD), Mössbauer spectroscopy (MS), and magnetic measurements. XRD patterns show that the phase of intermediate was composed of spinel phase and corundum phase (α-Fe2O3). The 57Fe Mössbauer spectra show that the spinel phase originated from the magnetite particles. The structure transformation proportion of hematite to magnetite strongly depends on reaction times. After reflux for 28 hrs the hematite-magnetite transformation was complete. The mean crystallite size of pure phase of magnetite particles is about 40 nm. The saturation magnetization increases with the reaction time, which corresponds to an increase of concentration of magnetite in the samples. A pronounced feature of the Hc and σr/σs observed in samples is the steplike change which appears at 125 K and is characteristic of the Verwey transition. The hyperfine parameters of Mössbauer spectrum measured at low temperature also indicate that the Verwey phase transition occurs. In other words, the Verwey transition is an indication that the magnetite particles exactly grew up in the synthesized compounds. This thermal decomposition process provided a method to prepare pure magnetite as well as magnetite/hematite nanocomposites useful for various magnetic applications.