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11.
An experimental study on electro-spraying from small-scale combustors is carried out using liquid ethanol as fuel. Two systems of electro-spraying are employed in the present study; one is a nozzle system (without a ring electrode) and the other is a nozzle-ring system (with a ring electrode). The photos of electro-spraying at the cone-jet mode are taken by a digital camera. The voltage drop across the resistance in the loop is measured by a data acquisition instrument, and the atomization current is calculated according to Ohm's Law. The size and velocity of electro-spraying droplets are measured by a Phase Doppler Anemometer. A non-dimensional analysis on atomization current is completed to explain the electro-spraying phenomena of liquid at the stable cone-jet mode. The results show that, the lower atomization current and droplet velocity corresponds to smaller size of droplet. Based on the results of non-dimensional analysis, it is found that the dimensionless atomization current in both the nozzle system and nozzle-ring system obeys the scaling law as square root of the dimensionless flow rate. The charge density is of a −1.5 power dependence on droplet diameter. Both of the nozzle and the nozzle-ring systems show a good agreement with Rayleigh instability. 相似文献
12.
The optical torque and the trapping position (focal point) in optical tweezers are analyzed for upward-directed focused laser
illumination using a ray optics model, considering that laser light is incident at not only the lower surface but also the
side surface of a 3-wing rotor. The viscous drag force due to the pressure and the shearing stress on all surfaces of the
rotor is evaluated using computational fluid dynamics. The rotation rate is simulated in water by balancing the optical torque
with the drag force, resulting in 500 rpm for an SU-8 rotor with 20 μm diameter at a laser power of 200 mW. The trapping position
is estimated to be 7.6 μm in the rotor with an upward-directed laser at 200 mW via an objective lens having a numerical aperture
of 1.4. Both the rotation rate and the trapping position agree well with the values obtained in the experiment. 相似文献
13.
A new method to protect the copyright of digital museum based on digital holography is proposed. The Fresnel hologram of watermark image is embedded in the object to be protected through discrete wavelet transform (DWT). After the watermark detection, the copyright information appears in the reconstructed hologram. With the higher redundancy feature in the hologram, the proposed technique can actually survive several kinds of image processing. Experimental results prove that the presented method has good robustness in image protection. 相似文献
14.
K.?KeutelEmail author H.?Fuchs C.?Edelmann 《Applied Physics A: Materials Science & Processing》2004,78(5):687-690
Originally, modified pulsed arc discharge was used for reactive coatings, for example for the deposition of nitrides on different substrate materials. Scientific studies of this process have shown that the droplet emission, in comparison to the direct current (DC) random arc process, is strongly reduced by the operation of a pulsed arc. Recently, the influence of the process parameters on the properties of the thin films produced was investigated. The interesting film properties from our work are the layer structure, the surface roughness and the microhardness. Electrical arc parameters, for example pulse current and pulse frequency, bias voltage and deposition conditions, like pressure, influence the thin-film properties in different ways. The dependence of the layer properties on the different operating parameters of the coating process are demonstrated and discussed. Furthermore, the plasma was investigated by optical emission spectroscopy in respect to composition and ion charge. The results obtained are used to discuss the influence of the operation conditions of the modified pulsed arc process on the properties of the layers produced. PACS 81.15.Ef; 52.25.Jm; 68.47.De; 68.35.Ct 相似文献
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X.S. Qin G.H. Huang G.M. Zeng A. Chakma Y.F. Huang 《European Journal of Operational Research》2007,180(3):182
Planning for water quality management systems is complicated by a variety of uncertainties and nonlinearities, where difficulties in formulating and solving the resulting inexact nonlinear optimization problems exist. With the purpose of tackling such difficulties, this paper presents the development of an interval-fuzzy nonlinear programming (IFNP) model for water quality management under uncertainty. Methods of interval and fuzzy programming were integrated within a general framework to address uncertainties in the left- and right-hand sides of the nonlinear constraints. Uncertainties in water quality, pollutant loading, and the system objective were reflected through the developed IFNP model. The method of piecewise linearization was developed for dealing with the nonlinearity of the objective function. A case study for water quality management planning in the Changsha section of the Xiangjiang River was then conducted for demonstrating applicability of the developed IFNP model. The results demonstrated that the accuracy of solutions through linearized method normally rises positively with the increase of linearization levels. It was also indicated that the proposed linearization method was effective in dealing with IFNP problems; uncertainties can be communicated into optimization process and generate reliable solutions for decision variables and objectives; the decision alternatives can be obtained by adjusting different combinations of the decision variables within their solution intervals. It also suggested that the linearized method should be used under detailed error analysis in tackling IFNP problems. 相似文献
17.
《International Journal of Plasticity》2005,21(8):1568-1590
There generally exist two void nucleation mechanisms in materials, i.e. the breakage of hard second-phase particle and the separation of particle–matrix interface. The role of particle shape in governing the void nucleation mechanism has already been investigated carefully in the literatures. In this study, the coupled effects of particle size and shape on the void nucleation mechanisms, which have not yet been carefully addressed, have been paid to special attention. To this end, a wide range of particle aspect ratios (but limited to the prolate spheroidal particle) is considered to reflect the shape effect; and the size effect is captured by the Fleck–Hutchinson phenomenological strain plasticity constitutive theory (Advance in Applied Mechanics, vol. 33, Academic Press, New York, 1997, p. 295). Detailed theoretical analyses and computations on an infinite block containing an isolated elastic prolate spheroidal particle are carried out to light the features of stress concentrations and their distributions at the matrix–particle interface and within the particle. Some results different from the scale-independent case are obtained as: (1) the maximum stress concentration factor (SCF) at the particle–matrix interface is dramatically increased by the size effect especially for the slender particle. This is likely to trigger the void nucleation at the matrix–particle interface by cleavage or atomic separation. (2) At a given overall effective strain, the particle size effect significantly elevates the stress level at the matrix–particle interface. This means that the size effect is likely to advance the interface separation at a smaller overall strain. (3) For scale-independent cases, the elongated particle fracture usually takes place before the interface debonding occurs. For scale-dependent cases, although the SCF within the particle is also accentuated by the particle size effect, the SCF at the interface rises at a much faster rate. It indicates that the probability of void nucleation by the interface separation would increase. 相似文献
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19.
Xiangxue Wang Shujun Yu Zhongshan Chen Wencheng Song Yuantao Chen Tasawar Hayat Ahmed Alsaedi Wei Guo Jun Hu Xiangke Wang 《中国科学:化学(英文版)》2017,60(1):107-114
To contribute to the understanding of Eu(III) interaction preperties on hydrous alumina particles in the absence and presence of fulvic acid (FA), the complexation properties of Eu(III) with hydrous alumina, FA and FA-alumina hybrids are studied by batch and time-resolved laser fluorescence spectroscopy (TRLFS) techniques. The continuous increase in the fluorescence lifetime of Eu-alumina and Eu-FA with increasing pH indicates that the complexation is accompanied by decreasing number of hydration water in the first coordination sphere of Eu(III). Eu(III) is adsorbed onto alumina particles as outer-sphere surface complexes of ≡(Al?O)?Eu· (OH)· 7H2O and ≡(Al?O)?Eu· 6H2O at low pH values, and as inner-sphere surface complexes as ≡(Al?O)2?Eu+· 4H2O at high pH. In FA solution, Eu(III) forms complexes with FA as (COO)2Eu+(H2O) x and the hydration water number in the first coordination sphere decreases with pH increasing. The formation of ≡COO?Eu?(O?Al≡)· 4H2O is observed on FA-alumina hybrids, suggesting the formation of strong inner-sphere surface complexes in the presence of FA. The surface complexes are also characterized by their emission spectra [the ratio of emission intensities of 5 D 0→7 F 1 (λ=594 nm) and 5 D 0→7 F 2 (λ=619 nm) transitions] and their fluorescence lifetime. The findings is important to understand the contribution of FA in the complexation properties of Eu(III) on FA-alumina hybrids that the clarification of the environmental behavior of humic substances is necessary to understand fully the behavior of Eu(III), or its analogue trivalent lanthanide and actinide ions in natural environment. 相似文献
20.
Shujun Yu Xiangxue Wang Shitong Yang Guodong Sheng Ahmed Alsaedi Tasawar Hayat Xiangke Wang 《中国科学:化学(英文版)》2017,60(2):170-187
The X-ray absorption fine structure (XAFS) technology has exhibited a very unique application in the study of sorption mechanism, chemical species and microstructures of radionuclides at the natural solid-water interfaces. In this review, the interaction mechanism of radionuclides with clay minerals and nanomaterials under different environmental conditions are summarized from the XAFS spectroscopy analysis. The coordination number and the bond distances of radionuclides, the oxidation-reduction reactions, the influence of humic substances and microorganisms on the species and structures of radionuclides at molecule level are reviewed and compared. This review is helpful to understand the interactions of radionuclides with oxides, natural clay minerals and nanomaterials, which is also crucial to evaluate the physicochemical behaviors of radionuclides in the natural environment. 相似文献