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排序方式: 共有221条查询结果,搜索用时 15 毫秒
1.
A comparative analysis of such methods of defuzzification of fuzzy numbers as WABL (Weighted Averaging Based on Levels), centroid, and mean of maxima (MOM) is presented in the study. Analytic formulas are presented for calculating the defuzzification values for parametrically represented fuzzy numbers of triangular and trapezoidal form. 相似文献
2.
Poly(acrylamide‐co‐maleic acid) [P(AAm/MA)] hydrogels, with various compositions, were prepared from ternary mixtures of acrylamide (AAm)/maleic acid (MA)/water by using 60Co γ‐rays. The effect of composition of these hydrogels, on the competitive removal of Pb2+, Cd2+, and Zn2+ ions from aqueous solution, was investigated. The hydrogel compositions and their adsorption behaviors were determined by use of differential pulse polarography, a very sensitive electroanalytical technique. It was observed that the external stimuli of pH, temperature, and ionic strength have an important role on the adsorption. The increments of MA content in P(AAm/MA) hydrogels caused a significant increase in the adsorption these ions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2401–2406, 2004 相似文献
3.
Autonomous use of legged robots in unstructured, outdoor settings requires dynamically dexterous behaviors to achieve sufficient
speed and agility without overly complex and fragile mechanics and actuation. Among such behaviors is the relatively under-studied
pronking (aka. stotting), a dynamic gait in which all legs are used in synchrony, usually resulting in relatively slow speeds but
long flight phases and large jumping heights. Instantiations of this gait for robotic systems have been mostly limited to
open-loop strategies, suffering from severe pitch instability for underactuated designs due to the lack of active feedback.
However, both the kinematic simplicity of this gait and its dynamic nature suggest that the Spring-Loaded Inverted Pendulum
model (SLIP) would be a good basis for the implementation of a more robust feedback controller for pronking. In this paper,
we describe how template-based control, a controller structure based on the embedding of a simple dynamical “template” within a more complex “anchor” system, can
be used to achieve very stable pronking for a planar, underactuated hexapod robot. In this context, high-level control of
the gait is regulated through speed and height commands to the SLIP template, while the embedding controller ensures the stability
of the remaining degrees of freedom. We use simulation studies to show that unlike existing open-loop alternatives, the resulting
control structure provides explicit gait control authority and significant robustness against sensor and actuator noise. 相似文献
4.
An assessment of total RMR classification system using unified simulation model based on artificial neural networks 总被引:1,自引:0,他引:1
Engineering design has great importance in the cost and safety of engineering structures. Rock mass rating (RMR) system has
become a reliable and widespread pre-design system for its ease of use and variety in engineering applications such as tunnels,
foundations, and slopes. In RMR system, six parameters are employed in classifying a rock mass: uniaxial compressive strength
of intact rock material (UCS), rock quality designation (RQD), spacing of discontinuities (SD), condition of discontinuities
(CD), condition of groundwater (CG), and orientation of discontinuities (OD). The ratings of the first three parameters UCS,
RQD, and SD are determined via graphic readings where the last three parameters CD, CG, and OD are estimated by the tables
that are composed of interval valued linguistic expressions. Because of these linguistic expresions, the estimated rating
values of the last three become fuzzy especially when the related conditions are close to border of any two classes. In such
cases, these fuzzy situations could lead up incorrect rock class estimations. In this study, an empirical database based on
the linguistic expressions for CD, CG, and OD is developed for training Artificial Neural Network (ANN) classifiers. The results
obtained from graphical readings and ANN classifiers are unified in a simulation model (USM). The data obtained from five
different tunnels, which were excavated for derivation purpose, are used to evaluate classification results of conventional
method and proposed model. Finally, it is noted that more accurate and realistic ratings are reached by means of proposed
model. 相似文献
5.
An image analysis method and its validation are presented for tracking the displacements of parallel mechanical force sensors. Force is measured using a combination of beam theory, optical microscopy, and image analysis. The primary instrument is a calibrated polymeric microbeam array mounted on a micromanipulator with the intended purpose of measuring traction forces on cell cultures or cell arrays. One application is the testing of hypotheses involving cellular mechanotransduction mechanisms. An Otsu-based image analysis code calculates displacement and force on cellular or other soft structures by using edge detection and image subtraction on digitally captured optical microscopy images. Forces as small as 250+/-50 nN and as great as 25+/-2.5 microN may be applied and measured upon as few as one or as many as hundreds of structures in parallel. A validation of the method is provided by comparing results from a rigid glass surface and a compliant polymeric surface. 相似文献
6.
An adaptive signal compression system with pre-specified reconstruction quality and compression rate
Two essential properties of a signal compression method are the compression rate and the distance between the original signal and the reconstruction from the compressed signal. These two properties are used to assess the performance and quality of the method. In a recent work [B. Tümer, B. Demir?z, Lecture Notes in Computer Science-Computer and Information Sciences, volume 2869, chapter Signal Compression Using Growing Cell Structures: A Transformational Approach, Springer Verlag, 2003, pp. 952-959], an adaptive signal compression system (ACS) is presented which defines the performance of the system as a function of the system complexity, system sensitivity and data size. For a compression method, it is desirable to formulate the performance of the system as a function of the system complexity and sensitivity to optimize the performance of the system. It would be further desirable to express the reconstruction quality in terms of the same system parameters so as to know up front what compression rate to end up with for a specific reconstruction quality. In this work, we modify ACS such that the modified ACS (MACS) estimates the reconstruction quality for a given system complexity and sensitivity. Once this relation is identified it is possible to optimize either compression rate or reconstruction quality with respect to system sensitivity and system complexity while limiting the other one. 相似文献
7.
We formulate the signal-to-noise ratio (SNR) for free-space optical links. Upon inserting typical operating parameters, it is seen that SNR well approximates to the inverse of aperture averaged scintillation parameter. By adopting a common source beam power of 10 mW, we select three different source sizes of Gaussian, annular Gaussian (AG), and cosh-Gaussian beams. We then evaluate the SNR of these beams. Our results indicate that when fixed aperture opening is used, fully and partially coherent beams yield almost the same SNR performance. On the other hand, however, focusing and lowering wavelength of operation appear to be quite instrumental in improving the SNR performance. In this context, medium-sized AGB seems to exhibit the best performance. 相似文献
8.
By making use of new Lyapunov type inequalities, we establish disconjugacy and stability criteria for discrete Hamiltonian systems. The stability criteria are given when the system is periodic. 相似文献
9.
There are various algorithms used for binary classification where the cases are classified into one of two non-overlapping classes. The area under the receiver operating characteristic (ROC) curve is the most widely used metric to evaluate the performance of alternative binary classifiers. In this study, for the application domains where the high degree of imbalance is the main characteristic and the identification of the minority class is more important, we show that hit rate based measures are more correct to assess model performances and that they should be measured on out of time samples. We also try to identify the optimum composition of the training set. Logistic regression, neural network and CHAID algorithms are implemented for a real marketing problem of a bank and the performances are compared. 相似文献
10.
Rheological,Thermodynamic, and Gas Solubility Properties of Phenylacetic Acid‐Based Deep Eutectic Solvents 下载免费PDF全文
Tausif Altamash Mert Atilhan Amal Aliyan Ruh Ullah Mustafa Nasser Santiago Aparicio 《化学工程与技术》2017,40(4):778-790
Choline chloride + phenylacetic acid‐based deep eutectic solvents are studied. Their most relevant experimental physicochemical properties at different mixing ratios together with the CO2 solubility data obtained in wide pressure and temperature ranges are reported. The presented materials exhibit a significant CO2 capture performance with low corrosion effect when compared with the most common amine‐based CO2 capture agents. Detailed rheological measurements are carried out and various models are applied to describe the dynamic flow behavior of the solvents. The CO2 absorption mechanism is evaluated by studying the behavior of the liquid gas and interface. Due to the advantages of low cost, nontoxicity, and favorable physical properties, these solvents are an environmentally promising alternative for effective CO2 capture technological applications. 相似文献