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排序方式: 共有2711条查询结果,搜索用时 15 毫秒
51.
52.
Zafer Iscan Ayhan Yüksel Zümray Dokur Mehmet Korürek Tamer Ölmez 《Digital Signal Processing》2009,19(5):890-901
In this study, a novel incremental supervised neural network (ISNN) is proposed for the segmentation of medical images. Performance of the ISNN is investigated for tissue segmentation in medical images obtained from various imaging modalities. Two feature extraction methods based on transform and moments are comparatively investigated to segment the tissues in medical images. Two-dimensional (2D) continuous wavelet transform (CWT) and the moments of the gray-level histogram (MGH) are computed in order to form the feature vectors of ultrasound (US) bladder and phantom images, X-ray computerized tomography (CT) and magnetic resonance (MR) head images. In the 2D-CWT method, feature vectors are formed by the intensity of one pixel of each wavelet-plane of different energy bands. The MGH represents the tissues within the sub-windows by using the spatial variation of image intensities. In this study, the ISNN and Grow and Learn (GAL) network are employed for the segmentation task. It is observed that the ISNN has significantly eliminated the disadvantages of the GAL network in the segmentation of the medical images. 相似文献
53.
Mehmet Önder Efe 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2009,13(1):23-29
This paper presents an approach to improve the performance of intelligent sliding model control achieved by the use of a fundamental
constituent of soft computing, named Adaptive Linear Element (ADALINE). The proposed scheme is based on the fractional calculus.
A previously considered tuning scheme is revised according to the rules of fractional order differintegration. After a comparison
with the integer order counterpart, it is seen that the control system with the proposed adaptation scheme provides (1) better
tracking performance, (2) suppression of undesired drifts in parameter evolution and (3) a very high degree of robustness
and insensitivity to disturbances. The claims are justified through some simulations utilizing the dynamic model of a two
degrees of freedom (DOF) direct drive robot arm and overall, the contribution of the paper is to introduce the fractional
order calculus into a robust and nonlinear control problem with some outperforming features that are absent when the integer
order differintegration operators are adopted. 相似文献
54.
Summary The polymerization of methyl methacrylate (MMA), ethyl acrylate (EA), styrene (St) and 2-vinyl pyridine (VP) is initiated upon irradiation at >350 nm of dichloromethane solutions containing N-ethoxy-2-methylpyridinium hexafluorophosphate (EMP+PF6
-) and anthracene or thioxanthone. Initiation mechanisms involving the formation of ethoxyl radicals during the decomposition of EMP+ ions via electron transfer are proposed. 相似文献
55.
Emrah Öncü Rasit Tutgun Emre Aktas 《International Journal of Satellite Communications and Networking》2023,41(6):589-598
Conventional solid-state power amplifier (SSPA) design approach isolates radio frequency (RF) design from communication theory. In this paper, a unified SSPA design approach is proposed, which optimizes SSPA parameters (bias voltage and input RF signal power) to minimize total DC power consumption while satisfying received SNR constraint specified by the link budget. The effect of SSPA nonlinearity is quantified by the error vector magnitude measured at its output and the corresponding received SNR degradation is analyzed. Using the quantitative metrics for received SNR, it is possible to evaluate highly nonlinear SSPA classes such as Class-B or deep-Class AB, which are normally not considered in conventional SSPA design approach to be used in satellite communication applications. 相似文献
56.
This article aims to explore the impact of the integration of risk factors into delayed milestones for construction projects. A simulation model was developed to determine the impact of schedule variability on cost estimation. To generate random scenarios a Monte Carlo Simulation (MCS) technique was applied. The developed model computes the cost impact of delayed milestone in the expected budget. Using a risk integration approach revealed the critical time frame that may lead to a budget deficit for a project. As a result, a number of cost-sensitive risk factors and schedule delays were identified for the critical time period where the risk of budget deficit increases. The method of integration proposed in this article highlights the priority of risk factors and schedule delays for construction contracts involving Payments at Event Occurrences (PEO). Consequently, the developed method can be useful for practitioners in anticipation of potential increase of costs, hence, prevention of failure due to budget deficit. 相似文献
57.
A Review of Metal Fabricated with Laser‐ and Powder‐Bed Based Additive Manufacturing Techniques: Process,Nomenclature, Materials,Achievable Properties,and its Utilization in the Medical Sector 下载免费PDF全文
58.
Ümit Işıkdağ Aycan Hepsağ Süreyya İmre Bıyıklı Derya Öz Gebrail Bekdaş Zong Woo Geem 《计算机、材料和连续体(英文)》2023,74(1):113-129
Construction Industry operates relying on various key economic indicators. One of these indicators is material prices. On the other hand, cost is a key concern in all operations of the construction industry. In the uncertain conditions, reliable cost forecasts become an important source of information. Material cost is one of the key components of the overall cost of construction. In addition, cost overrun is a common problem in the construction industry, where nine out of ten construction projects face cost overrun. In order to carry out a successful cost management strategy and prevent cost overruns, it is very important to find reliable methods for the estimation of construction material prices. Material prices have a time dependent nature. In order to increase the foreseeability of the costs of construction materials, this study focuses on estimation of construction material indices through time series analysis. Two different types of analysis are implemented for estimation of the future values of construction material indices. The first method implemented was Autoregressive Integrated Moving Average (ARIMA), which is known to be successful in estimation of time series having a linear nature. The second method implemented was Non-Linear Autoregressive Neural Network (NARNET) which is known to be successful in modeling and estimating of series with non-linear components. The results have shown that depending on the nature of the series, both these methods can successfully and accurately estimate the future values of the indices. In addition, we found out that Optimal NARNET architectures which provide better accuracy in estimation of the series can be identified/discovered as result of grid search on NARNET hyperparameters. 相似文献
59.
H. Böcük B. A. Albiss İ Ercan H. Özkan N. Gasanly 《Journal of Low Temperature Physics》1996,105(3-4):975-980
Voltage-current characteristics of YBCO superconductor was studied under magnetic field up to 0.4 T at different temperatures below Tc. The critical temperature decreases and the transition width broadens under magnetic field. V-I data below Tc were fitted to a power law expression V I(T,B) in which (T,B) is found to decrease with increase of magnetic field and temperature, gradually approaching unity as T approaches Tc, being independent of magnetic field. Similarly, (T,B) approaches unity as magnetic field increases being independent of temperature. 相似文献
60.
Local feature-based approaches mainly aim to achieve robustness to variations in facial images by assuming that only some
parts of the facial images may be affected. However, such approaches may lose spatial information. In this study, a compromise
feature extraction scheme is studied which extracts local features while preserving spatial information. The proposed scheme
exploits an ensemble of classifiers where each member is constructed using randomly selected design parameters including the
size, number and location of sub-images for local feature extraction. Experiments conducted on FERET and ORL databases have
shown that proposed scheme surpasses the local feature-based reference systems which focus on either local information or
preserving spatial information. 相似文献