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51.
This study aims to investigate the contributions of online promotional marketing and online reviews as predictors of consumer product demands. Using electronic data from Amazon.com, we attempt to predict if online review variables such as valence and volume of reviews, the number of positive and negative reviews, and online promotional marketing variables such as discounts and free deliveries, can influence the demand of electronic products in Amazon.com. A Big Data architecture was developed and Node.JS agents were deployed for scraping the Amazon.com pages using asynchronous Input/Output calls. The completed Web crawling and scraping data-sets were then preprocessed for Neural Network analysis. Our results showed that variables from both online reviews and promotional marketing strategies are important predictors of product demands. Variables in online reviews in general were better predictors as compared to online marketing promotional variables. This study provides important implications for practitioners as they can better understand how online reviews and online promotional marketing can influence product demands. Our empirical contributions include the design of a Big Data architecture that incorporate Neural Network analysis which can used as a platform for future researchers to investigate how Big Data can be used to understand and predict online consumer product demands. 相似文献
52.
Structural phase transformations of rare-earth modified transition alumina to corundum 总被引:1,自引:0,他引:1
The effect of rare-earth dopant on transformations of the γ→θ→ phases in fine alumina powders under vacuum was investigated by in situ neutron diffraction from 500 to 1300 °C. La-doped (1 mol%) Al2O3 powders (surface area 170 m2/g) were prepared by an impregnation technique. Below 800 °C both samples contain a dominant γ-phase. Above 1000 °C, transformation of the γ-phase to the intermediate θ-phase, and then completely to the -phase (corundum) was observed. Addition of 1 mol% of La in Al2O3 effectively shifts the -phase formation temperature from 1125 °C for pure alumina to 1250 °C, probably due to the larger size of La compared to Al ions, which hinders ionic diffusion in the processes of sintering and transformation. Consequently, doping La in alumina improves the surface-area and thermal stability at high temperatures, which is important for catalytic applications. 相似文献
53.
Qunyi Tong Qian Xiao Loong‐Tak Lim 《International Journal of Food Science & Technology》2013,48(4):870-878
The effects of glycerol, sorbitol, xylitol and fructose plasticisers on water sorption, mechanical properties, water vapour permeability (WVP) and microstructure of pullulan–alginate–carboxymethycellulose (PAC) blend films were investigated. At low plasticiser concentrations (below 7% w/w dry basis), antiplasticisation effect was observed, causing an increase in tensile strength (TS) but a decrease in the equilibrium moisture content. As glycerol concentration increased from 0% to 7%, TS increased from 68.1 to 69.6 MPa, whereas equilibrium moisture contents at 0.84 aw decreased from 0.37 to 0.3 g H2O g?1 dry basis. At higher plasticiser concentrations (14–25% w/w), an opposite trend was observed on the PAC films, resulting in the reduction of TS and elevation of moisture content. Among the four plasticisers tested, the fructose‐plasticised films were the most brittle, showing the highest TS, but had the lowest elongation at break (EAB), WVP and equilibrium moisture content values than films plasticised with other polyols. On the other hand, glycerol resulted in the most flexible film structure, exhibiting opposite materials' properties as compared with the fructose‐plasticised films. For instance, at 25% (w/w) plasticiser concentration, EAB and WVP values of fructose‐plasticised films were 33.5% and 3.48 × 10?6 g m Pa?1 h?1 m?2, which were significantly lower than that of glycerol‐plasticised films (58.6% and 4.86 × 10?6 g m Pa?1 h?1 m?2, respectively). Scanning electron microscopy showed that the plasticised PCA films were less homogeneous and more porous than the unplasticised counterparts, indicating that plasticisers had an effect on the microstructural morphology of the film matrix. 相似文献
54.
Security Challenges in the IP-based Internet of Things 总被引:1,自引:0,他引:1
Tobias Heer Oscar Garcia-Morchon René Hummen Sye Loong Keoh Sandeep S. Kumar Klaus Wehrle 《Wireless Personal Communications》2011,61(3):527-542
A direct interpretation of the term Internet of Things refers to the use of standard Internet protocols for the human-to-thing or thing-to-thing communication in embedded networks.
Although the security needs are well-recognized in this domain, it is still not fully understood how existing IP security
protocols and architectures can be deployed. In this paper, we discuss the applicability and limitations of existing Internet
protocols and security architectures in the context of the Internet of Things. First, we give an overview of the deployment
model and general security needs. We then present challenges and requirements for IP-based security solutions and highlight
specific technical limitations of standard IP security protocols. 相似文献
55.
Ran Zhang Zhiqiang Chen Zhifeng Huang Yongshun Xiao Xuewu Wang Jie Wie C.-K. Loong 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,651(1):12-15
Since the launching of the Compact Pulsed Hadron Source (CPHS) project of Tsinghua University in 2009, works have begun on the design and engineering of an imaging/radiography instrument for the neutron source provided by CPHS. The instrument will perform basic tasks such as transmission imaging and computerized tomography. Additionally, we include in the design the utilization of coded-aperture and grating-based phase contrast methodology, as well as the options of prompt gamma-ray analysis and neutron-energy selective imaging. Previously, we had implemented the hardware and data-analysis software for grating-based X-ray phase contrast imaging. Here, we investigate Geant4-based Monte Carlo simulations of neutron refraction phenomena and then model the grating-based neutron phase contrast imaging system according to the classic-optics-based method. The simulated experimental results of the retrieving phase shift gradient information by five-step phase-stepping approach indicate the feasibility of grating-based neutron phase contrast imaging as an option for the cold neutron imaging instrument at the CPHS. 相似文献
56.
57.
Silicified microcrystalline cellulose pellets with hydroxypropyl methylcellullose (HPMC) as modifier were prepared using a mixed solvent as liquid binder. Pellets were produced using extrusion-spheronization with a mixed solvent consisting of water and isopropanol as liquid binder. The key spheronization aid was Prosolv® SMCC 90. Low viscosity grade HPMC was incorporated aiming to modify release of indometacin. Physical characteristics including breaking load, apparent density and flow properties, particle size distribution and shape were determined. Drug loaded pellets were also tested for dissolution profiles. By adjusting liquid binder property, at isopropanol to water ratio of 3.5 to 6.5, pellets of desirable size and shape with reasonable yields were obtained. Pellets exhibited good flow property and they were mechanically strong. Pellet with higher HPMC content displayed a faster drug dissolution profile. This was because low viscosity grade HPMC was not enough to create strong gel. Instead hydration of HPMC molecules increased matrix's hydrophilicity and weakened the structure of pellet faster. The release of indometacin was partly based on the erosion of hydrated matrix. The presence of HPMC in the pellets would require a mixed solvent to produce desirable shape. Incorporation of HPMC had modified drug release from the pellets without further coating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47924. 相似文献
58.
A large class of visual systems in the biological world often has multiple eyes in simultaneous motion and yet has little
or no overlap in the visual fields between the eyes. These systems include the lateral eyes found in many vertebrates and
the compound eyes in insects. Instead of computing feature correspondences between the eyes, which might not even be possible
due to the lack of overlap in the visual fields, we exploit the organizational possibility offered by the eye topography.
In particular, we leverage on the pair of visual rays that are parallel to each other but opposite in direction, and compute
what we call the quasi-parallax for translation recovery. Besides resulting in parsimonious visual processing, the quasi-parallax
term also enhances the information pick-up for the translation, as it is almost rotation-free. The rotation is subsequently
recovered from a pencil of visual rays using the individual epipolar constraints of each camera. As a result of using these
different and appropriate aspects of visual rays for motion recovery, our method is numerically more effective in disambiguating
the translation and rotation. In comparison to the gold standard solution obtained by the bundle adjustment (BA) technique,
our method has a better Fisher information matrix for a lateral eye pair, as well as a superior experimental performance under
the case of narrow field of view. For other eye configurations, the two methods achieve comparable performances, with our
linear method slightly edging the nonlinear BA method when there exists imperfection in the calibration. 相似文献
59.
Numerical Modeling of Casting Processes 总被引:4,自引:0,他引:4
J.-F. Hétu D.M. Gao K.K. Kabanemi S. Bergeron K.T. Nguyen C.A. Loong 《Advanced Performance Materials》1998,5(1-2):65-82
Recent progress on work related to numerical modeling of casting processes at the Industrial Materials Institute (IMI) is presented. Depending on the type of casting process involved, two different modeling approaches are used. The first, applied to simulate laminar or turbulent flow in the cavity of thin wall castings, is based on a 2D shell element model. This has the advantage of being computationally efficient from the CPU standpoint while, at the same time, provides a reasonably accurate solution to the problem. In the second approach, a 3D finite element method is used for parts that are thick (such as in low pressure or gravity casting), or where the problem is associated with both the part and mold (such as in heat transfer calculations). Whatever the technique chosen, in performing numerical modeling, the foundry hopes to use the results to optimize die and part design, as well as to reduce manufacturing costs. By being able to predict filing, solidification, stresses and shrinkage, a good idea of product quality and performance can often be obtained at the initial stage of the product development cycle.Examples of simulations conducted using an experimental die, an automotive housing and a wheel in an aluminum alloy are given. 相似文献
60.
High-surface-area rare-earth (RE) modified zirconia powders prepared by solution methods can be used as catalytic support of noble metals and as electrolyte oxygen sensors in an automobile exhaust-emission-control system. A previous neutron-scattering study showed that substituting zirconium with trivalent RE ions not only stabilizes the cubic and tetragonal phases over a wide range of temperatures, but also creates oxygen vacancies in the RE–Zr oxide solid solution. This work focuses on the fluorescence of Nd in Nd0.1Zr0.9O1.95 powders under laser excitation of the Nd3+ ground state to the 4G7/2 states. Distinct features were observed at 8 K in the 4I9/2→4G7/2 excitation and 4F3/2→4I9/2 emission spectra using two sets of incident and emission frequencies, respectively. The results are discussed in terms of site-sensitive local structures surrounding the Nd ions in the two-phased oxide structure. 相似文献