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41.
The feasibility problem for constant scaling in output feedback control is considered. This is an inherently difficult problem since the set of feasible solutions is non-convex and may be disconnected. Nevertheless, we show that this problem can be reduced to the global minimization of a concave function over a convex set, or alternatively, to the global minimization of a convex program with an additional reverse convex constraint. Thus this feasibility problem belongs to the realm of d.c. optimization, a new field which has recently emerged as an active promising research direction in nonconvex global optimization. By exploiting the specific d.c. structure of the problem, several algorithms are proposed which at every iteration require solving only either convex or linear subproblems. Analogous algorithms with new characterizations are proposed for the bilinear matrix inequality (BMI) feasibility problem. 相似文献
42.
In this paper we derive an explicit expression for the log likelihood function of a continuous-time autoregressive model. Then, using earlier results relating the autoregressive coefficients to the set of positive parameters called residual variances ratios, we develop an iterative algorithm for computing the maximum likelihood estimator of the model, similar to one in the discrete-time case. A simple noniterative estimation method, which can be used to produce an initial estimate for the algorithm, is also proposed. 相似文献
43.
A wide variety of problems in control system theory fall within the class of parameterized Linear Matrix Inequalities (LMIs), that is, LMIs whose coefficients are functions of a parameter confined to a compact set. However, in contrast to LMIs, parameterized LMI (PLMIs) feasibility problems involve infinitely many LMIs hence are very hard to solve. In this paper, we propose several effective relaxation techniques to replace PLMIs by a finite set of LMIs. The resulting relaxed feasibility problems thus become convex and hence can be solved by very efficient interior point methods. Applications of these techniques to different problems such as robustness analysis, or Linear Parameter-Varying (LPV) control are then thoroughly discussed and illustrated by examples. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
44.
Pham Huy Thong Florentin Smarandache Phung The Huan Tran Manh Tuan Tran Thi Ngan Vu Duc Thai Nguyen Long Giang Le Hoang Son 《计算机系统科学与工程》2023,46(2):1981-1997
Clustering is a crucial method for deciphering data structure and producing new information. Due to its significance in revealing fundamental connections between the human brain and events, it is essential to utilize clustering for cognitive research. Dealing with noisy data caused by inaccurate synthesis from several sources or misleading data production processes is one of the most intriguing clustering difficulties. Noisy data can lead to incorrect object recognition and inference. This research aims to innovate a novel clustering approach, named Picture-Neutrosophic Trusted Safe Semi-Supervised Fuzzy Clustering (PNTS3FCM), to solve the clustering problem with noisy data using neutral and refusal degrees in the definition of Picture Fuzzy Set (PFS) and Neutrosophic Set (NS). Our contribution is to propose a new optimization model with four essential components: clustering, outlier removal, safe semi-supervised fuzzy clustering and partitioning with labeled and unlabeled data. The effectiveness and flexibility of the proposed technique are estimated and compared with the state-of-art methods, standard Picture fuzzy clustering (FC-PFS) and Confidence-weighted safe semi-supervised clustering (CS3FCM) on benchmark UCI datasets. The experimental results show that our method is better at least 10/15 datasets than the compared methods in terms of clustering quality and computational time. 相似文献
45.
Zhi Ding Tuan Nguyen 《Signal Processing, IEEE Transactions on》2000,48(6):1587-1596
Blind source separation has been the subject of extensive research. In particular, blind antenna beamforming is an effective signal separation technique for communication systems to combat co-channel interference. Among many potential candidate approaches, the simple constant modulus algorithm (CMA) has been widely studied and used in practice. The CMA is designed to capture and separate signals with negative kurtosis. However, when some signals have positive kurtoses, the CMA is unable to capture and separate these sources. We show that the kurtosis maximum algorithm (KMA) can capture signals with both the positive and negative kurtoses. Its global convergence proof is presented for noiseless systems with multiple signals sources and for systems with a single source and zero-kurtosis (such as Gaussian) additive noise 相似文献
46.
裂缝发育段是潜山内幕油藏主要储集空间。辽河油田在兴隆台潜山内幕油藏勘探开发实践中,注重挖掘裂缝发育段的井眼信息响应特征以及各种信息间的匹配关系,认识到裂缝发育段在钻井过程中钻井液易漏失,录井显示级别高、气测异常明显、地球化学录井与轻烃录井含油指标突出,测井信息特征明显,且不同信息之间表现出较好的耦合关系,大大提高了裂缝发育段识别的准确性。为投产选择射孔层段、储量计算中有效厚度的合理划分、潜山内幕油藏立体开发模式的建立提供了可靠的地质基础。有效指导了辽河油田潜山内幕油藏的勘探开发工作,实现了兴隆台潜山亿吨级规模储量的快速探明和百万吨年产能力快速建成,以及油藏的有效开发、高效开发。 相似文献
47.
Hsin-Neng Wang Janna K. Register Andrew M. Fales Naveen Gandra Eugenia H. Cho Alina Boico Gregory M. Palmer Bruce Klitzman Tuan Vo-Dinh 《Nano Research》2018,11(8):4005-4016
Although nanotechnology has led to important advances in in vitro diagnostics, the development of nanosensors for in vivo detection remains very challenging. Here, we demonstrated the proof-of-principle of in vivo detection of nucleic acid targets using a promising type of surface-enhanced Raman scattering (SERS) nanosensor implanted in the skin of a large animal model (pig). The in vivo nanosensor used in this study involves the “inverse molecular sentinel” detection scheme using plasmonics-active nanostars, which have tunable absorption bands in the near infrared region of the “tissue optical window”, rendering them efficient as an optical sensing platform for in vivo optical detection. Ex vivo measurements were also performed using human skin grafts to demonstrate the detection of SERS nanosensors through tissue. In this study, a new core–shell nanorattle probe with Raman reporters trapped between the core and shell was utilized as an internal standard system for self-calibration. These results illustrate the usefulness and translational potential of the SERS nanosensor for in vivo biosensing. 相似文献
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50.
Tuan Vo-Dinh Guy Griffin David L. Stokes Alan Wintenberg 《Sensors and actuators. B, Chemical》2003,90(1-3):104-111
We describe a multi-functional biochip (MFB), which uses two different types of bioreceptors, including nucleic acid and antibody probes, on a single platform. The multi-functional capability of the MFB device for biomedical diagnostics is illustrated by measurements of DNA probes specific to gene fragments of Bacillus anthracis and antibody probes targeted to Escherichia coli. Calibration curves for monitoring pathogenic species using antibody probes against E. coli and DNA probes for B. anthracis illustrate the capability of the device for medical diagnostics and for quantitative detection of pathogenic agents. 相似文献