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排序方式: 共有307条查询结果,搜索用时 15 毫秒
1.
We show that determining the minimum number of resolve filters that need to be added to a set of two-dimensional (2-D) prefix filters so that the filter set can implement a given policy using the first-matching-rule-in-table tie breaker is NP-hard. Additionally, we develop a fast O(nlogn+s) time, where n is the number of filters and s is the number of conflicts, plane-sweep algorithm to detect and report all pairs of conflicting 2-D prefix filters. The space complexity of our algorithm is O(n). On our test set of 15 2-D filter sets, our algorithm runs between 4 and 17 times as fast as the 2-D trie algorithm of A. Hari et al. (2000) and uses between 1/4th and 1/8th the memory used by the algorithm of Hari et al. On the same test set, our algorithm is between 4 and 27 times as fast as the bit-vector algorithm of Baboescu and Varghese (2002) and uses between 1/205 and 1/6 as much memory. We introduce the notion of an essential resolve filter and develop an efficient algorithm to determine the essential resolve filters of a prefix filter set. 相似文献
2.
Compared with grinding, hard turning is competitive in many cases, with substantial benefits. However, hard turning applications are not preferred, due to the existence of the process-induced white layer on the component surface, which is often assumed to be detrimental to component life. Nevertheless, white layer properties have not been well understood or clearly defined, especially the properties of the white layer induced in hard turning as against grinding. A clear understanding of white layer properties will provide a solid physics basis for product performance analysis and useful data for process selection. In this study, benchmark hard turning and cylindrical grinding experiments were conducted to generate thick white layers for reliable measurement. It was found that the properties of white and dark layers by hard turning and grinding are fundamentally different in four aspects: surface structure characteristics, microhardness, microstructures, and chemical composition. A white layer is not untempered martensite in terms of retained austenite. Additionally, a thick white layer can be produced in grinding under certain conditions. 相似文献
3.
Streptokinase (SK) exerts its thrombolytic effect by activating plasminogen (PG) indirectly, after the formation of an equimolar complex with either PG or plasmin (PN). The location and nature of the PG/PN-binding sites in SK have been explored using limited proteolysis with immobilized trypsin. Employing Western blotting with radiolabeled PG after SDS-PAGE of total tryptic digest, three fragments of MW 7 kD, 19 kD and 31 kD were found to possess PG-binding ability. Each of these fragments was then isolated by reverse phase HPLC and characterised with respect to its sequence, as well as its PG-binding properties by ELISA. These analyses revealed that in addition to a PG-binding site in the region 143-293 reported recently in the literature, there is another distinct, high-affinity and independent PG-binding site, located in the N-terminal region (residues 1-59) of SK. Using a synthetic peptide, the N-terminally located PG-binding-site has been further localised to the region 37-51 of SK. Further, we demonstrate that the PG-binding of this peptide is not mediated through the lysine-binding sites ("Kringles") of PG. This stretch contains a short sequence (LTSRPA) that is also present in the PG-binding domain of human fibronectin. 相似文献
4.
Ritika Puri Mohit Mahajan Nikhil Shri Sahajpal Harjeet Singh Harmanpreet Singh 《Drug development and industrial pharmacy》2016,42(7):1032-1041
Context: Docosahexanoic acid (DHA) is an essential omega-3 fatty acid for normal brain development and its use has increased considerably in recent years.Objective: The aim of this study is to develop and evaluate self-nanoemulsifying drug delivery systems (SNEDDS) of DHA for improved palatability, dispersibility and bioavailability.Methods: The SNEDDS were prepared and evaluated for miscibility, employing different combinations of olive oil and soyabean oil as oil phase, Span 80, Span 20, soya phosphatidylcholine, Labrafil M 1944 CS as surfactants while Tween 80, PEG 400, Cremophor RH40 and propylene glycol as cosurfactants. Thermodynamically stable SNEDDS were characterized for dispersibility, self-emulsification time, droplet size, zeta potential along with sensory analysis. The optimized formulation was subjected to ex vivo and in vivo evaluation such as intestinal permeability, memory performance test, brain concentration and histopathology studies.Results: The optimized SNEDDS formulation showed emulsification time of 27?±?4.7?s with droplet size of 17.6?±?3.5?nm and zeta potential of??37.6?±?0.5?mV. Intestinal absorption study depicted 18.3%, 21.5%, 41.5%, 98.7% absorption of DHA with SNEDDS-based formulation in comparison to 8.2%, 15.1%, 28.8%, 46.1% absorption of DHA with oil-based marketed formulation after 0.5, 1, 2 and 4?h. DHA concentration in brain homogenate was found to be increased to 2.6-fold in comparison to DHA-marketed formulation. This could be ascribed to enhanced dispersibility and bioavailability of DHA from nanosized formulation.Conclusion: The developed formulation led to enhanced dispersibility and bioavailability of DHA due to the formation of nanodroplets. 相似文献
5.
We develop optimal or near optimal algorithms to multiply matrices and perform commonly occurring data permutations and BPC permutations on multiprocessor computers interconnected by a partitioned optical passive stars network 相似文献
6.
We report on the development of an electrostatic ion trap for high-resolution mass spectrometry. The trap works on purely electrostatic fields and hence trapping and storing of ions is not mass restrictive, unlike other techniques based on Penning, Paul, or radio frequency quadrupole ion traps. It allows simultaneous trapping and studying of multiple mass species over a large mass range. Mass spectra were recorded in "dispersive" and "self-bunching" modes of ions. Storage lifetimes of about 100 ms and mass resolving power of about 20,000 could be achieved from the fifth harmonic Fourier transform spectrum of Xe ions recorded in the self-bunching mode. 相似文献
7.
Polyethersulfone (PES) composites were developed with carbon fabric (CF). Cold remote nitrogen oxygen plasma (CRNOP) treatment
was employed to the CF to incorporate functional groups and promote fiber–matrix adhesion. This study includes the effect
of PES melt flow index (MFI) on the wettability of CF and its influence on fretting wear performance. Evaluations of fretting
wear properties of composites led to the conclusion that the CRNOP treatment proved beneficial to enhance performance properties
significantly. Polymer MFI and treatment to CF proved to be the decisive parameters for controlling performance of composites
apart from operating parameters. Perforations on the treated carbon fiber, evidently observed by FESEM, improved the fiber–matrix
adhesion, and hence the performance properties. Artificial neuron network (ANN) was used for prediction of the wear behavior
of composites. 相似文献
8.
Aminolytic chemical recycling is performed for obtaining NN′ diethyl 1,4 benzene dicarboxamide, NN′ dibutyl 1,4 benzene dicarboxamide, and NN′ dihexyl 1,4 benzene dicarboxamide from Polyethylene terephthalate bottle waste. The compounds were characterized through Fourier transform Infrared spectroscopy, Raman spectroscopy, UV–Visible spectroscopy, 1H NMR, 13C NMR, mass spectrometry, and elemental analysis. Thermal properties were also analyzed with the help of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Density Functional Theory (DFT) study has been performed at GGA-BLYP (Becke's and Lee–Yang–Parr) functional using SZ basis set to investigate the vibrational frequencies and physical parameters. Experimental vibrational frequencies were found in good accord with the experimental values. Calorific values of the products have been determined using bomb calorimeter as per standard ASTM D240. The values have been correlated with increment of methylene units from NN′ diethyl BdCA to NN′ dihexyl BdCA using standard molar enthalpies of carbon and hydrogen. SEM and EDX analysis of the char residues after combustion has also been carried out to insight the effect of N-alkyl chain length on calorific values. The calorific values of the recovered compounds are comparable to commercial solid fuels and the compounds may find potential applications in aerospace industry. 相似文献
9.
Flash and distillation systems evolving on the equilibrium manifold possess stable steady states when the molar flows and the boundary conditions are fixed and a vapor and liquid phase is present at all times. The results extend the range of validity of a local stability theorem for linear, constant molar overflow systems due to Acrivos and Amundson. The approach to stability analysis is motivated by the tangent plane method developed by Gibbs to open systems as it takes advantage of the negative curvature of the entropy surface to construct a Lyapunov function. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3322–3332, 2013 相似文献
10.
Management Issues of a Mobile Agent-Based Service Environment 总被引:1,自引:0,他引:1
This paper introduces the concepts of a servicemanagement system for mobile agent-based services. Incontrast to several other approaches in whichagent-based applications are used to handletraditional network or service managementaspects, this paper describes a way to manage thedistributed agent environment itself. The proposedapproach was designed and developed by using OSI SystemsManagement concepts as a starting point, which are modified andadjusted in order to fulfill the new requirementsassociated with the mobile agent paradigm. However, thispaper does not cover integration or co-existence of the introduced agent management system (AMS)and traditional OSI management systems. Instead, theentire AMS environment is based on mobile agenttechnology. At present, this approach is validated inthe context of the European research project MobileAgent Environments in Intelligent Networks(MARINE). 相似文献