Adaptive Priority Sliding Admission Control and Scheduling Scheme for DCF and EDCA WLANs

In this paper an Adaptive Priority Sliding Admission Control and Scheduling (APSAS) scheme is proposed to provide QoS over the existing IEEE802.11 WLANs which operate on Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) mechanisms. The roles of this scheme are generally two folds: (1) To control the number of delay-sensitive real time flows that can be admitted into the WLAN Basic Service Set network and (2) To adjust the priority of selected real time flows in order to accommodate more real time flows without violating the QoS requirement. Extensive simulation studies show that APSAS improves the total throughput, flow throughput ratio, packets end-to-end delay, and jitter of the real time applications when compared with conventional best effort and scheduling-enhanced DCF/EDCA. APSAS also offers near to unity average throughput ratio, lower mean VoIP end-to-end packet delay (<130 ms) and lower mean video packet jitter (<130 ms) over DCF and EDCA.     

Mechanical,thermal, and morphology properties of poly(lactic acid) plasticized with poly(ethylene glycol) and epoxidized palm oil hybrid plasticizer

Poly(lactic acid) (PLA) has received great attention recently due to its good physical and mechanical properties such as high tensile strength and modulus, good processability and biodegradability. In this study, low molecular weight poly(ethylene glycol) (PEG) and epoxidized palm oil (EPO) were used as hybrid plasticizers to improve toughness and ductility of PLA. Using the solubility parameter, a tentative evaluation of the hybrid plasticizer that could act as the most effective plasticizer for PLA has been performed and the obtained results have been corroborated with the materials physical properties. Excellent plasticizing effect was obtained by hybrid plasticizer PEG:EPO with ratio 2:1. Addition of PEG:EPO (2:1) hybrid plasticizer to PLA shows a significant improvement of 12,402%, compared to neat PLA. The improvement in flexibility and decrease in rigidity for the plasticized PLA is well evidenced by lower glass transition temperature (T_g) and tensile modulus values. In relation to the thermal stability, a decrease in thermal properties of the hybrid plasticized PLA was observed due to the volatility of the plasticizers. Scanning electron microscopy (SEM) shows that the hybrid plasticizer was turned PLA's smooth surface to fibrous structure and rough fracture surface. POLYM. ENG. SCI., 56:1169–1174, 2016. © 2016 Society of Plastics Engineers     

Plasticized poly(lactic acid) with low molecular weight poly(ethylene glycol): Mechanical,thermal, and morphology properties

Poly(lactic acid) PLA was plasticized with low molecular weight poly(ethylene glycol) PEG‐200 to improve the ductility of PLA, while maintaining the plasticizer content at maximum 10 wt%. Low molecular weight of PEG enables increased miscibility with PLA and more efficient reduction of glass transition temperature (T_g). This effect is enhanced not only by the low molecular weight but also by its higher content. The tensile properties demonstrated that the addition of PEG‐200 to PLA led to an increase of elongation at break (>7000%), but a decrease of both tensile strength and tensile modulus. The plasticization of the PLA with PEG‐200 effectively lowers T_g as well as cold‐crystallization temperature, increasing with plasticizer content. SEM micrographs reveal plastic deformation and few long threads of a deformed material are discernible on the fracture surface. The use of low molecular weight PEG‐200 reduces the intermolecular force and increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4576–4580, 2013     

Coriolis and rotating buoyancy effect on detailed heat transfer distributions in a two-pass square channel roughened by 45° ribs at high rotation numbers

Heat transfer measurements from a rotating two-pass square channel with two opposite leading and trailing walls roughened by 45° parallel ribs arranged in the staggered manner are performed to examine the effects of Reynolds (Re), rotation (Ro) and buoyancy (Bu) numbers on local and area-averaged Nusselt numbers (Nu and $\overline{\mathit{Nu}}$). Full-field Nu distributions over the two rib-roughened leading and trailing walls are measured at the conditions of 4000 ? Re ? 16,000, 0 ? Ro ? 0.8 and 0.0015 ? Bu ? 0.93 (0.05 ? Δρ/ρ ? 0.1) using the infrared thermography which allows for the detailed examination of the Coriolis and rotating buoyancy effects on Nu distributions over the rotating ribbed surface. Selected heat transfer data in term of Nu ratio between rotating and stationary levels illustrates the influences of rotation on local and area-averaged heat transfer performances. Area-averaged $\overline{\mathit{Nu}}$ for the turn region and the inlet and outlet ribbed legs of the rotating two-pass channel are parametrically analyzed to devise a set of empirical heat transfer correlations that permits the evaluation of the interdependent and individual effects of Re, Ro and Bu on $\overline{\mathit{Nu}}$.     

Thermally Stable Nanocrystalline Steel

Metallurgical and Materials Transactions A - Two novel nanocrystalline steels were designed to withstand elevated temperatures without catastrophic microstructural changes. In the most successful...     

Carrier Transportation Mechanism of the $hbox{TaN}/ hbox{HfO}_{2}/hbox{IL}/hbox{Si}$ Structure With Silicon Surface Fluorine Implantation

In this paper, the current transportation mechanism of HfO₂ gate dielectrics with a TaN metal gate and silicon surface fluorine implantation is investigated. Based on the experimental results of the temperature dependence of gate leakage current and Fowler-Nordheim tunneling characteristics at 77 K, we have extracted the current transport mechanisms and energy band diagrams for TaN/HfO₂/IL/Si structures with fluorine incorporation, respectively. In particular, we have obtained the following physical quantities: 1) fluorinated and as-deposited interfacial layer (IL)/Si barrier heights (or conduction band offsets) at 3.2 and 2.7 eV; 2) TaN/fluorinated and as-deposited HfO₂ barrier heights at 2.6 and 1.9 eV; and 3) effective trapping levels at 1.25 eV (under both gate and substrate injections) below the HfOF conduction band and at 1.04 eV (under gate injection) and 1.11 eV (under substrate injection) below the HfO₂ conduction band, which contributes to Frenkel-Poole conduction.     

An analytical model for all-optical packet switching networks with finite FDL buffers

Signal loss and noise accumulation can cause fading in optical buffers implemented by fiber delay lines (FDLs). Optical packets that excessively recirculate through FDLs are easily dropped from their routing paths. Therefore, analytical models and packet scheduling schemes require additional considerations for FDL buffers. This work proposes an analytical model for all-optical packet switching networks with finite FDL buffers and a general class of scheduling schemes including many basic scheduling schemes. We intend to minimize the packet loss probability by ranking packets to achieve an optimal balance between latency and residual lifetime in the general class of scheduling schemes. The analytical model is based on a non-homogeneous Markovian analysis to study the effects of various scheduling schemes on packet loss probability and average latency. Analytical results show how various network parameters affect the optimal balance, and illustrate how properly balancing latency and residual distance can significantly improve network performance.     

Experimental verification of a radar target discrimination technique using multiple‐frequency amplitude returns

Abstract

An experimental study of radar target discrimination using multiple‐frequency scattering amplitude without phase data is presented. Based on the concept of natural resonance frequencies, the technique is aspect‐angle independent so that a priori information of the aspect‐angle is not necessary. The radar cross sections of a spheroid and a thin wire are measured at different aspect ‐ and bistatic‐angles to distinguish different spheroids and wires in the resonance frequency range. The results show that the discrimination algorithm works well and can be applied to both monostatic and bistatic radars.     

Phase Separation-Mediated Chromatin Organization and Dynamics: From Imaging-Based Quantitative Characterizations to Functional Implications

As an effective and versatile strategy to compartmentalize cellular components without the need for lipid membranes, phase separation has been found to underpin a wide range of intranuclear processes, particularly those involving chromatin. Many of the unique physico-chemical properties of chromatin-based phase condensates are harnessed by the cell to accomplish complex regulatory functions in a spatially and temporally controlled manner. Here, we survey key recent findings on the mechanistic roles of phase separation in regulating the organization and dynamics of chromatin-based molecular processes across length scales, packing states and intranuclear functions, with a particular emphasis on quantitative characterizations of these condensates enabled by advanced imaging-based approaches. By illuminating the complex interplay between chromatin and various chromatin-interacting molecular species mediated by phase separation, this review sheds light on an emerging multi-scale, multi-modal and multi-faceted landscape that hierarchically regulates the genome within the highly crowded and dynamic nuclear space. Moreover, deficiencies in existing studies also highlight the need for mechanism-specific criteria and multi-parametric approaches for the characterization of chromatin-based phase separation using complementary techniques and call for greater efforts to correlate the quantitative features of these condensates with their functional consequences in close-to-native cellular contexts.