Quality-aware Wi-Fi offload: analysis,design and integration perspectives

The rapid spread of smart wireless devices and expansion of mobile data traffic have increased the interest for efficient traffic offloading techniques in next-generation communication technologies. Wi-Fi offloading uses ubiquitous Wi-Fi technology in order to satisfy the ever increasing demand for mobile bandwidth and therefore is an appropriate methodology for mobile operators. As a matter of fact, design and integration of an offloading technology inside mobile network operators’ infrastructures is a challenging task due to convergence issues between the The 3rd Generation Partnership Project (3GPP) and non-3GPP networks. Therefore, a connectivity management platform is a key element for integrated heterogeneous mobile network operators in order to enable smart and effective offloading. In this paper, analysis, design and integration of a connectivity management platform that uses a Multiple Attribute Decision Making (MADM) algorithm for efficient Wi-Fi Offloading in heterogeneous wireless networks is presented. In order to enhance the end-user’s quality-of-experience (QoE), we have especially concentrated on the benefits that can be achieved by exploiting the presence of integrated service provider platform. Hence, the proposed platform can collect several User Equipment (UE) and network-based attributes via infrastructure and client Application Programming Interfaces (APIs) and decides on the best network access technology (i.e. 3GPP and non-3GPP) to connect to for requested users. We have also proposed multi-user extensions of the MADM algorithms for offloading. Through simulations and experiments, we provide details of the comparisons of the proposed algorithms as well as the sensitivity analysis of the MADM algorithm through an experimental set-up.     

Phenomenological characterization of fabrication of aligned pristine‐SWNT and COOH‐SWNT nanocomposites via dielectrophoresis under AC electric field

Dielectrophoresis under the application of AC electric fields is one of the primary fabrication techniques (DEPFT) for obtaining aligned carbon nanotube (CNT)–polymer nanocomposites, and is used here to generate data sets from which DEPFT fabrication models in terms of CNT dispersion and orientation distribution can be developed. While the general understanding of how CNTs form aligned filaments under the influence of dielectrophoretic forces and moments is well established, detailed multi‐CNT‐filament formation predictions of microstructure evolution from a random dispersion into a more ordered structure remain intractable. As such, effort here is focused towards the development of phenomenological fabrication models for controlling local CNT dispersion and orientation as a function of applied electric field magnitude, frequency, and exposure time. In this study, 0.03 wt% single‐wall nanotubes (SWNTs) and acid treated functionalized SWNTs (COOH‐SWNTs) were dispersed in a photopolymerizable monomer blend (urethane dimethacrylate (UDMA) and 1,6‐hexanediol dimethacrylate (HDDMA)). Ultrasonication techniques were used to obtain the two different acrylate solutions i.e., 0.03% SWNTs/ UDMA/ HDDMA(9/1) solution and a 0.03% COOH‐SWNTs/UDMA/HDDMA(9/1) solution, consisting of randomly oriented, well dispersed SWNTs. Pristine SWNTs and acid treated SWNTs solutions were then subjected to controlled AC electric fields in order to explore the formation of aligned SWNT‐filaments. To assess key morphological features of the as‐produced SWNT‐acrylate and SWNT‐COOH‐acrylate nanocomposite samples, such as SWNT distribution and filament thicknesses, transmission optical microscopy has been used to observe the SWNT alignment and filament formation obtained by digitally mapping individual overlapping images. The acquisition of a large field of view with high magnification allows statistically meaningful distribution functions for morphological features to be constructed. Measurements of the as‐produced nanocomposite electrical properties in the SWNT alignment direction and transverse to it were used as a macroscale measure to confirm alignment and contiguity of the SWNT‐filament structure, with polarized Raman spectroscopy used to assess the degree of SWNT alignment at the local microscale level. It is observed that a combination of exposure time to AC electric field, and its frequency, is the key driver of filament thickness and spacing and that in general, the COOH‐SWNTs align to a greater extent than the pristine SWNTs, though they do not form filaments that are as thick and contiguous for the exposure times studied. POLYM. COMPOS., 36:1266–1279, 2015. © 2014 Society of Plastics Engineers     

Current transport mechanisms and trap state investigations in (Ni/Au)-AlN/GaN Schottky barrier diodes

The current transport mechanisms in (Ni/Au)-AlN/GaN Schottky barrier diodes (SBDs) were investigated by the use of current-voltage characteristics in the temperature range of 80-380 K. In order to determine the true current transport mechanisms for (Ni/Au)-AlN/GaN SBDs, by taking the J_s(tunnel), E₀, and R_s as adjustable fit parameters, the experimental J-V data were fitted to the analytical expressions given for the current transport mechanisms in a wide range of applied biases and at different temperatures. Fitting results show the weak temperature dependent behavior in the saturation current and the temperature independent behavior of the tunneling parameters in this temperature range. Therefore, it has been concluded that the mechanism of charge transport in (Ni/Au)-AlN/GaN SBDs, along the dislocations intersecting the space charge region, is performed by tunneling.In addition, in order to analyze the trapping effects in (Ni/Au)-AlN/GaN SBDs, the capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics were measured in the frequency range 0.7-50 kHz. A detailed analysis of the frequency-dependent capacitance and conductance data was performed, assuming the models in which traps are located at the heterojunction interface. The density (D_t) and time constants (τ_t) of the trap states have been determined as a function of energy separation from the conduction-band edge (E_c − E_t) as D_t≅(5-8)×10¹², respectively.     

QoSMOS: cross-layer QoS architecture for wireless multimedia sensor networks

Wireless multimedia sensor networks (WMSNs), having inherent features and limited resources, require new quality of service (QoS) protocols for real-time and multimedia applications. In this paper, we present a cross-layer QoS architecture (QoSMOS), that unifies network and link layers into a single communication module for QoS provisioning. Based on QoSMOS architecture, we developed an example reference cross-layer protocol, named cross-layer communication protocol (XLCP), enabling scalable service differentiation in WMSNs. Comprehensive analysis of simulation results indicate that the proposed architecture successfully differentiates service classes in terms of soft delay, reliability and throughput domains. A comparative analysis of XLCP and its counterparts is also given to show the superiority of the cross-layer protocol.     

A Review of the Alleged Health Hazards of Monosodium Glutamate

Monosodium glutamate (MSG) is an umami substance widely used as flavor enhancer. Although it is generally recognized as being safe by food safety regulatory agencies, several studies have questioned its long‐term safety. The purpose of this review was to survey the available literature on preclinical studies and clinical trials regarding the alleged adverse effects of MSG. Here, we aim to provide a comprehensive overview of the reported possible risks that may potentially arise following chronic exposure. Preclinical studies have associated MSG administration with cardiotoxicity, hepatotoxicity, neurotoxicity, low‐grade inflammation, metabolic disarray, and premalignant alterations, along with behavioral changes. However, in reviewing the available literature, we detected several methodological flaws, which led us to conclude that these studies have limited relevance for extrapolation to dietary human intake of MSG risk exposure. Clinical trials have focused mainly on MSG effects on food intake and energy expenditure. Besides its well‐known impact on food palatability, MSG enhances salivary secretion and interferes with carbohydrate metabolism, while the impact on satiety and post‐meal recovery of hunger varied in relation to meal composition. Reports on MSG hypersensitivity or links of its use to increased pain sensitivity and atopic dermatitis were found to have little supporting evidence. Many of the reported negative health effects of MSG have little relevance for chronic human exposure and are poorly informative as they are based on excessive dosing that does not meet with levels normally consumed in food products. We conclude that further clinical and epidemiological studies are needed, with an appropriate design, accounting for both added and naturally occurring dietary MSG.     

桥梁结构状态参数监测技术研究现状

桥梁的自然老化、劣化将会影响其安全与正常使用,甚至造成重大的人员伤亡和财产损失,已成为交通运输部门关注的问题。为了有效维护桥梁和确保其安全运行,监测桥梁结构的关键状态参数对于全面及时反映桥梁工作状态和进一步开展安全性评估极为重要。综述了桥梁结构的应变、挠度、振动等关键状态参数监测技术的研究进展,并分析了这些监测技术的基本原理、性能、应用范围,同时,对未来桥梁结构状态参数监测的发展提出了建议。     

热烈欢迎下一代照明技术可调白光LED的到来

单一的白光LED难以满足色彩与照明的应用需求．可调LED将是更好的选择 随着固态照明技术的性能与效率不断超越传统照明技术,该新技术得到了广泛应用。不过,如果我们只是用静态白光LED来取代传统技术的话,就难以真正发挥固态照明技术的全部潜力,不能充分实现产品的特色化。在智能驱动器支持下,LED照明灯具不仅能取代白光照明,而且还能实现新的功能,而这些功能用传统的照明技术是很难实现的。     

Statistical investigation of wave power potential in the North Aegean Sea

Clean Technologies and Environmental Policy - Wave energy is recognized as a significant renewable energy source with a high energy density and very low environmental impact. Today, in parallel...     

Selective and Sustainable Production of Sub-terminal Hydroxy Fatty Acids by a Self-Sufficient CYP102 Enzyme from Bacillus Amyloliquefaciens

Enzymatic hydroxylation of fatty acids by Cytochrome P450s (CYPs) offers an eco-friendly route to hydroxy fatty acids (HFAs), high-value oleochemicals with various applications in materials industry and with potential as bioactive compounds. However, instability and poor regioselectivity of CYPs are their main drawbacks. A newly discovered self-sufficient CYP102 enzyme, BAMF0695 from Bacillus amyloliquefaciens DSM 7, exhibits preference for hydroxylation of sub-terminal positions (ω-1, ω-2, and ω-3) of fatty acids. Our studies show that BAMF0695 has a broad temperature optimum (over 70 % of maximal enzymatic activity retained between 20 to 50 °C) and is highly thermostable (T₅₀ >50 °C), affording excellent adaptive compatibility for bioprocesses. We further demonstrate that BAMF0695 can utilize renewable microalgae lipid as a substrate feedstock for HFA production. Moreover, through extensive site-directed and site-saturation mutagenesis, we isolated variants with high regioselectivity, a rare property for CYPs that usually generate complex regioisomer mixtures. BAMF0695 mutants were able to generate a single HFA regiosiomer (ω-1 or ω-2) with selectivities from 75 % up to 91 %, using C12 to C18 fatty acids. Overall, our results demonstrate the potential of a recent CYP and its variants for sustainable and green production of high-value HFAs.     

Effects of sintering and zirconmullite doping on nanostructural vacancies of bovine hydroxyapatite by positron techniques

In this study, the nanostructural vacancy behavior of bovine derived hydroxyapatite (BHA) doped with powder zirconmullite (ZM) contents of 5, 7.5, 10 and 12.5 wt.% were presented at sintering temperatures of 1000, 1100, 1200 and 1300°C. ZM-doped BHA (ZM-BHA) was characterized by X-ray diffraction and positron annihilation lifetime spectroscopy (PALS). Density and hardness behavior were measured with respect to increasing sintering temperature. PALS results indicate that the longest lifetime component τ₃ of ortho-positronium (o-Ps) localized at open spaces is attributed to the vacancy site and almost constant with the ZM contents and the sintering temperatures to have a mean value of 0.680 ns (corresponding to the radius of 0.997 nm). This average value is ascribed to the OH group defects along the main crystalline line. On the other hand, the o-Ps intensity attributed to the number of vacancy sites increases almost linearly with ZM additives and sintering temperatures. The intensity is also related to the density and hardness of ZM-BHA in terms of ZM contents.