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291.
Shane Esola Ivan Bartoli Suzanne E. Horner James Q. Zheng Antonios Kontsos 《Journal of Nondestructive Evaluation》2017,36(3):47
The application of impact-based nondestructive inspection to thick-sectioned laminate composite parts, although widely reported, is still hampered by a number of challenges. In this article, microphone-recorded impact response variations are associated with delaminations within a variety of test specimens, building in complexity from metal to composite simulant and finally toward the application of the method to hard armor protective inserts. Defective and defect-free states are verified a priori by both operator quality inspections and X-ray computed tomography. Potential delamination-discriminating metrics are determined by signal processing of vibroacoustic data. Prior reported “tap test” metrics that focus on impact force-time histories are shown to be insufficient for thick-sections laminates. The empirical results reported herein, additionally supported by simulations, suggest that large defects may be detectible via a frequency content analysis. Method limitations, potential confounds, and the extension to the case of smaller defects is discussed. 相似文献
292.
A single-electron universal Control-Control-Not gate (CCN gate) is presented in this paper. Bits of information are represented by the presence or absence of single-electrons at conducting islands. The logic operation of the CCN gate as well as its XOR, AND, NAND and NOT operation is verified using simulation. The stability of its universal operation is analysed using a Monte Carlo method. Stability analysis using free energy diagrams and stability plots verify the correct and stable operation of the gate. 相似文献
293.
This work investigated the effects of the use of a surfactant or the functionalization of single-walled carbon nanotubes (SWNTs) on their dispersion in uncrosslinked poly(propylene fumarate) (PPF) and the mechanical reinforcement of crosslinked composites as a function of the SWNT concentration. Rheological measurements showed good dispersion of SWNTs in uncrosslinked PPF at low concentrations of 0.05?wt% and SWNT aggregation for higher concentrations for all formulations examined. Mechanical testing demonstrated significant reinforcement in the compressive and flexural mechanical properties of crosslinked nanocomposites which peaked for low SWNT concentrations of the order of 0.05?wt%. For example, a 74% increase was recorded for the compressive modulus and a 69% increase for the flexural modulus of nanocomposites with functionalized SWNTs at a 0.05?wt% loading. Nevertheless, this reinforcement was not related to the use of a surfactant or the functionalization of the SWNTs tested. Scanning electron microscopy examinations of fractured nanocomposite surfaces revealed the formation of SWNT aggregates at higher concentrations corroborating the rheological and mechanical data. These results suggest that the dispersion of individual SWNTs in a uncrosslinked formulation is pivotal to the development of injectable nanocomposites for bone tissue engineering applications. 相似文献
294.
Food-grade PVC film containing 28.3% dioctyladipate (DOA) plasticizer was used to wrap chicken meat samples, with and without skin, contained in a polystyrene tray. Samples were then irradiated with γ-radiation [60Co] at doses equal to 4 kGy and 9 kGy corresponding to “cold pasteurization”. Irradiation was carried out at 8–10 °C and samples were subsequently stored at 4–5 °C. Contaminated chicken meat samples were analysed for DOA at intervals between 7 h and 240 h of contact, using an indirect GC method. Identical non-irradiated (control) samples were also analysed for their DOA content. Results showed no statistically significant differences in migrated amounts of DOA between irradiated and non-irradiated samples. Neither were differences observed between samples irradiated at 4 kGy and 9 kGy. This was supported by identical IR spectra recorded for irradiated and non-irradiated samples and leads to the conclusion that, at such intermediate radiation doses (?kGy), the migration characteristics of PVC film are not affected. DOA migration was found to be time dependent, approaching equilibrium after approximately 170 h for the chicken flesh plus skin samples and 120 h for the chicken flesh samples. The amount of DOA migrated into chicken flesh plus skin samples was significantly greater (3.2–22.3 mg/dm2) than that for chicken flesh samples (0.9–8.9 mg/dm2). After 240 h of sample/ film contact under refrigeration, loss of DOA was approximately 35.6% for chicken flesh plus skin samples and 14.3% for chicken flesh samples. Sample spoilage, as demonstrated by off-odour development, occurred after approximately 120 h of refrigerated storage. Diffusion coefficients for DOA were calculated and were found to be lower for chicken flesh (1×10?13) than for flesh plus skin (4.4×10?13) samples. 相似文献
295.
Antonios Deligiannakis Yannis Kotidis Nick Roussopoulos 《The VLDB Journal The International Journal on Very Large Data Bases》2007,16(4):439-461
Sensor nodes are small devices that “measure” their environment and communicate feeds of low-level data values to a base station
for further processing and archiving. Dissemination of these multi-valued feeds is challenging because of the limited resources
(processing, bandwidth, energy) available in the nodes of the network. In this paper, we first describe the SBR algorithm
for compressing multi-valued feeds containing historical data from each sensor. The key to our technique is the base signal, a series of values extracted from the real measurements that is used to provide piece-wise approximation of the measurements.
While our basic technique exploits correlations among measurements taken on a single node, we further show how it can be adapted
to exploit correlations among multiple nodes in a localized setting. Sensor nodes may form clusters and, within a cluster,
a group leader identifies and coalesces similar measurements taken by different nodes. This localized mode of operation further improves the accuracy of the approximation, typically by a factor from 5 to 15. We provide detailed
experiments of our algorithms and make direct comparisons against standard approximation techniques like Wavelets, Histograms
and the Discrete Cosine Transform, on a variety of error metrics and for real data sets from different domains. 相似文献
296.
In recent years, the search to develop large-area solar cells at low cost has led to research on photovoltaic (PV) systems based on nanocomposites containing conjugated polymers. These composite films can be synthesized and processed at lower costs and with greater versatility than the solid state inorganic semiconductors that comprise today's solar cells. However, the best nanocomposite solar cells are based on a complex architecture, consisting of a fine blend of interpenetrating and percolating donor and acceptor materials. Cell performance is strongly dependent on blend morphology, and solution-based fabrication techniques often result in uncontrolled and irreproducible blends, whose composite morphologies are difficult to characterize accurately. Here we incorporate three-dimensional hyperbranched colloidal semiconductor nanocrystals in solution-processed hybrid organic-inorganic solar cells, yielding reproducible and controlled nanoscale morphology. 相似文献
297.
Antonios Alexiou Christos Bouras Vasileios Kokkinos 《Wireless Personal Communications》2011,61(2):447-464
In mobile networks, the provision of rich multimedia services, such as Mobile TV, is considered of key importance. To this
end, Multimedia Broadcast/Multicast Service (MBMS)—that was introduced in the Release 6 of Universal Mobile Telecommunication
System (UMTS)—is envisaged to play an instrumental role in the proliferation of mobile market. The reason behind the design
of MBMS was the need to provide multiple users with the same data at the same time in 3GPP (3rd Generation Partnership Project)
cellular networks. Still, MBMS performance is limited by the base stations’ transmission power. As an aftermath, efficient
power allocation techniques should be implemented so as to ensure the mass provision of multimedia applications to mobile
users. This paper proposes a novel mechanism for efficient radio bearer selection during MBMS transmissions. The proposed
mechanism is based on the concept of transport channels combination in any cell of the network. Furthermore, the mechanism
exploits the performance enhancements emerged from Multiple Input Multiple Output (MIMO) antennas and manages to efficiently
deliver multiple MBMS sessions. The proposed mechanism is thoroughly evaluated and compared with the radio bearer selection
mechanisms proposed by 3GPP. 相似文献
298.
We present the exocytosis profile of two types of peptide-coated nanoparticles, which have similar charge and size but different functionality. While one kind of particles appears to progressively exocytose, the other one has a more complex profile, suggesting that some of the particles are re-uptaken by the cells. Both types of particles retain their colloidal stability after exocytosis. 相似文献
299.
Ignatios Fotiou Athanasios Baltopoulos Antonios Vavouliotis Vassilis Kostopoulos 《应用聚合物科学杂志》2013,129(5):2754-2764
The driver for this study is the observation that heating of carbon nanotubes (CNTs) with electromagnetic field can offer a more efficient and cost‐effective alternative in heat transfer for the production of composites. The idea of this study is twofold; CNT can work as microwave (MW) radiation susceptors and they can act as nanoreinforcements in the final system. To test these assumptions, a household oven was modified to control the curing schedule. Polymers with different CNT concentrations were prepared (0.5 and 1.0 wt %). The dispersion of the CNTs in the epoxy was achieved using shear‐mixing dissolver technique. MW and conventionally cured specimens were also produced in a convection oven for reference. Thermal and mechanical tests were used as control point. A curing schedule investigation was further performed to quantify the energy and time‐saving capabilities using CNT and MWs. The presence of CNTs into epoxy matrix has been proven beneficial for the shortening of the curing time. MW‐cured composites showed the same degree of polymerization with the conventionally cured composites in a shorter time period and this time was reduced as the CNT concentration was increased. A good distribution of the CNT is required to avoid hot spot effects and local degradation. Mechanical performance was, in some cases, favored by the use of CNT. The benefit from the use of MWs and CNT could reach at least 40% in terms of energy needed and time without sacrificing mechanical performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
300.
Dimitris Sarris Marios Giannakis Antonios Philippoussis Michael Komaitis Apostolis A. Koutinas Seraphim Papanikolaou 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(5):958-969
BACKGROUND: Olive mill wastewaters (OMWs) are an important residue and several methods have been proposed for their treatment. RESULTS: Remarkable decolorization (~63%) and phenol removal (~34% w/w) from OMW was achieved. In glucose‐based flask sterile cultures, enrichment with OMWs increased ethanol and biomass production compared with cultures without OMWs added. Flask sterile and un‐sterilized cultures demonstrated similar kinetic results. Batch‐bioreactor trials performed showed higher ethanol and lower biomass quantities compared with the respective shake‐flask experiments, while cultures used under un‐sterilized conditions revealed equivalent results to the sterile ones. In non‐sterile bioreactor cultures, OMWs addition enhanced biomass production in comparison with culture with no OMWs added, whereas ethanol biosynthesis was not affected. The maximum ethanol quantity achieved was 52 g L?1 (conversion yield per sugar consumed of 0.46 g g?1) in a batch bioreactor non‐sterilized trial with OMW–glucose enriched medium used as substrate, that presented initial reducing sugars concentration at ~115 g L?1. Fatty acid analysis of cellular lipids demonstrated that in OMW‐based media, cellular lipids containing increased concentrations of oleic and linoleic acid were produced in comparison with cultures with no OMWs added. CONCLUSIONS: S. cerevisiae simultaneously produced bio‐ethanol and biomass and detoxified OMWs, under non‐sterile conditions. © 2012 Society of Chemical Industry 相似文献