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91.
Abstract A study was made of the electrohydrodynamic (EHD) effect on the water evaporation rate of a channel flow with a needle-arrayed electrode system using both numerical and experimental methods. The local charged density, flow, and concentration distributions and their growth along the flow stream of a rectangular channel were described in detail. The results showed that the EHD effect on the evaporation rate increased with increases in applied voltage and electrode pitch and decreased in electrode height. For example, at an applied voltage of 16?kV, the mass transfer enhancement was 1.5 times than that of the electrode pitch from 50 to 100?mm at an electrode height of 20?mm. The mass transfer enhancement was twice as great for electrode height from 20 to 15?mm at an applied voltage of 12?kV and pitch of 100?mm. The present needle-arrayed electrode system results were compared with a five-wire electrode system based on the same geometric model and boundary conditions. It was concluded that the needle electrode cases achieved better mass transfer gains than the wire electrode cases for the present evaluated cases. Finally, the numerical results obtained satisfactory consistency with experimental data with a maximum error of 25%. 相似文献
92.
Leu Donald J.; DeGroff Linda-Jo C.; Simons Herbert D. 《Canadian Metallurgical Quarterly》1986,78(5):347
Examined the word-recognition and comprehension processes of 36 1st graders as they read a predictable text. Interactive-compensatory predictions related to comprehension were evaluated. Results suggest that when reading predictable texts, attention for both good and poor readers is available for comprehension processing but for different reasons. Consistent with predictions from the interactive-compensatory model by K. E. Stanovich (1980), good readers were able to attend to the meaning of a story because of automatic, context-free word-recognition skills. Poor readers were able to attend to the meaning of a story because of their automatic use of repetitive sentence context to facilitate word recognition. Thus, predictable texts may be appropriately used to provide comprehension opportunities for poorer readers. Predictable texts may give these students opportunities to engage in inferential reasoning and other comprehension processes, opportunities that infrequently occur because poor readers' attention is usually occupied by word-recognition demands. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
93.
Jenn-Sen Leu Papamarcou A. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1995,41(1):233-244
Three estimators of the exponent α in the power spectral density g(λ)=cg|λ|-α of fractional Brownian motion are evaluated. These are (i) the periodogram-based estimator αˆPG (ii) the maximum likelihood estimator αˆML; and (iii) the Allan (1966) variance-based estimator αˆAV. Large-sample properties of the mean-square error (MSE) and the associated sampling distribution are examined, αˆPG emphasis on the case α∈(1, 2). The MSE performance of αˆPG is judged to be inferior to that of both αˆML and αˆAV. The rate of decrease of MSE is the same for αˆML and αˆAV; the former estimator has smaller MSE, while the latter is less sensitive to departures from the power-law model and is considerably easier to compute 相似文献
94.
95.
Yeong-Bin Yang Jung-Huai Chou Liang-Jenq Leu 《International journal for numerical methods in engineering》1992,33(8):1597-1610
The purpose of the paper is to demonstrate how the concept of rigid body motions can be employed to derive the external stiffness matrix for an initially stressed finite element. Such a matrix is as important as the elastic and geometric stiffness matrices. It can be used not only in an eigenvalue analysis for testing the zero energy modes of a finite element under initial loadings, but for calculating the element forces in a step-by-step non-linear analysis. The two-dimensional beam element presented in this paper serves as a vehicle to demonstrate the concept involved. The principle of virtual work in its updated Lagrangian form has been adopted as the method of formulation. Several examples are provided to illustrate the adequacy of the present approach. 相似文献
96.
Two new naphthalene-ring-containing bis(ester-amine)s, 2,3-bis(4-aminobenzoyloxy)naphthalene (p-2) and 2,3-bis(3-aminobenzoyloxy)naphthalene (m-2), were prepared from the condensation of 2,3-dihydroxynaphthalene with 4-nitrobenzoyl chloride and 3-nitrobenzoyl chloride,
respectively, followed by catalytic hydrogenation. The novel aromatic poly(ester-amide)s and poly(ester-imide)s having 2,3-linked
bis(benzoyloxy)naphthalene units have been synthesized from the polycondensation reactions of bis(ester-amine)s (p-2 and m-2) or an equimolar mixture of 4,4′-oxydianiline and p-2 or m-2 with various aromatic dicarboxylic acids and dianhydrides. The synthesis of the poly(ester-amide)s was achieved by the phosphorylation
polyamidation reaction by means of triphenyl phosphate, and the synthesis of the poly(ester-imide)s included ring-opening
polyaddition to give poly(amic acid)s followed by chemical imidization to polyimides. Most of the poly(ester-amide)s were
readily soluble in various organic solvents. Six poly(ester-amide)s and two poly(ester-imide)s derived from less rigid diacids
and dianhydrides, respectively, were amorphous and could be solution-cast into transparent and tough films with good mechanical
properties. Most of the poly(ester-amide)s displayed discernible glass-transition temperatures (T
gs) between 192 and 223 °C in the DSC traces. All of the poly(ester-imide)s, except for one sample, showed clear T
g values between 225 and 265 °C by DSC. These poly(ester-imide)s showed excellent thermal stability with 10 wt% loss temperatures
above 460 °C in nitrogen or air. 相似文献
97.
Practical design and implementation of recognition assisted dynamic surveillance system 总被引:1,自引:0,他引:1
Jenq-Shiou Leu Hung-Jie Tzeng Chi-Feng Chen Wei-Hsiang LinAuthor vitae 《Computers & Electrical Engineering》2011,37(6):1182-1192
Open Service Gateway Initiative (OSGi) and Open-source Computer Vision (OpenCV) are widely used for developing applications. OSGi is constructed to provide a service platform with high application interoperability while OpenCV is used to provide many application programming interfaces (APIs) about image processing. In this paper, we design a recognition assisted surveillance system based on OSGi and OpenCV platforms. The system features dynamic monitoring by a camera carried by a robot and a Java 2 Micro-Edition (J2ME) viewer on a mobile phone. With the assistance of image recognition techniques, the captured frames are adaptively reproduced for handheld phones in a limited bandwidth environment. The proposed adaptive pause time control mechanism can efficiently improve the synchronization relationship between captured and viewed frames across heterogeneous networks. The evaluation results show that the proposed scheme can save power for the moveable camera and have a shorter time delay between the captured and viewed frames. 相似文献
98.
Chelsea Schelly Jessica Price Aimee Delach Rupak Thapaliya Karen Leu 《The Electricity Journal》2019,32(10):106678
The Long Island Solar Roadmap Project involves a collaborative research approach with multiple organizational entities and actors engaged in a stakeholder driven process. Long Island is a space-constrained region with a steep urban to rural gradient, resulting in a complex suite of local governments, development priorities, and utility, planning, and development actors. This project is integrating technological, economic, and social data into a spatial planning output that allows decision makers to see where mid-to-large scale solar development (capacity of 250 kW and larger) is technically, economically, and socially feasible. This spatial output involves innovative methods of evaluating site suitability based on criteria developed by stakeholders. The project’s stakeholder and partnership driven approach allow the team to consider technological and economic feasibility across a wide variety of solar development forms and financial models. Social science data collected via a residential electric utility ratepayer survey is used to examine the perceptual barriers and opportunities for solar development as well as the sites and types of solar development that community members are most likely to support. The Long Island Solar Roadmap Project is an example of how research and community engagement can improve solar development policy and planning. 相似文献
99.
This investigation aims to clarify the process conditions of the V-die bending operation of steel sheet. It provides a model which predicts the correct punch load for bending and the precise final shape of products after unloading, in relation to the tensile properties of the material and the geometry of tools. The process variables are punch radius (Rp), die radius (Rd), punch width (Wp), punch speed (Vp), friction coefficient (μ), strain hardening exponent (n) and normal anisotropy (R).This investigation is carried out by performing some experiments and by finite-element simulation. Experiments determine the punch for bending for various process variables, such as punch radius, punch speed and lubrication, were carried out. As a result it was found that punch load increases as punch radius and punch speed increase or lubrication decreases.An elasto-plastic incremental finite-element computer code based on an updated Lagrangian formulation was developed to simulate the V-die bending process of sheet metal under the plane-strain condition. Isotropic and normal anisotropic material behavior was considered including nonlinear work hardening. A modified Coulomb’s friction law was introduced to treat the alternation of sliding–sticking state of friction at the contact interface. Simulation results, such as the punch load of bending and the bend angle of the bent part after unloading, are compared with experimental data; satisfactory agreement was observed. The simulation clearly demonstrates that the code to simulate V-die bending process was efficient.Simulations were made to evaluate the effects of die radius, punch width, strain hardening exponent and normal anisotropy on punch load of bending. The punch load for bending is smaller for materials with a larger strain hardening exponent. The effect of punch width on punch load is limited. The punch load decreases in the early stage and increases in the final stage of the bending process as the die radius increases. The influences of all of the process variables on the final bend angle of the bent parts of sheet after unloading were also evaluated. The effects of process variables except die radius on the bend angle after unloading are also limited. The angle of spring-back is greater for tools with larger die radius. 相似文献
100.
Yaseen Iqbal Lii-Cherng Leu Muhammad Fahad Rick Ubic 《JOM Journal of the Minerals, Metals and Materials Society》2013,65(1):73-79
Pakistan is home to many varieties of minerals, some of which make it prominent in the mineral world. The exploration of Pakistan’s mineral wealth is far from complete and has rarely been conducted in the north and northwest of the country. This article presents the newest exploration and examination of minerals from an unexploited area in Pakistan. Several materials characterization techniques were carried out to examine and identify the phase and structure of the minerals, including x-ray diffraction, energy dispersive x-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy. In this study, several commonly found minerals are identified, including calcite, dolomite, quartz, talc, and fluorapatite. 相似文献