139,641 research outputs found
On the convergence properties of the modified Polak--Ribiere--Polyak method with the standard Armijo line search
No full textZhang et al. [IMA J. Numer. Anal., 26 (2006) 629--640] proposed a modified Polak--Ribiere--Polyak method for non-convex optimization and proved its global convergence with some backtracking type line search. We further study its convergence properties. Under the standard Armijo line search condition, we show that the modified Polak--Ribiere--Polyak method has better global convergence property and locally -linear convergence rate for non-convex minimization. Some preliminary numerical results are also reported to show its efficiency.
References C. Li, A conjugate gradient type method for the nonnegative constraints optimization problems, J. Appl. Math., Volume 2013, Article ID 986317, 6 pages. D. Li and B. Tian, -step quadratic convergence of the mprp method with a restart strategy, J. Comput. Appl. Math., 235 (2011) 4978--4990. J. J. More, B. S. Garbow and K. H. Hillstrom, Testing unconstrained optimization software, ACM Trans. Math. Softw., 7 (1981) 17--41. E. Polak and G. Ribiere, Note sur la convergence de methodes de directions conjuguees, Rev. Fr. Inform. Rech. Oper., 16 (1969) 35--43. B. T. Polyak, The conjugate gradient method in extreme problems, USSR Comput. Math. Math. Phys., 9 (1969) 94--112. L. Zhang, W. Zhou and D. Li, A descent modified Polak--Ribiere--Polyak conjugate gradient method and its global convergence, IMA J. Numer. Anal., 26 (2006) 629--640. H. Zhu, Y. Xiao and S. Wu, Large sparse signal recovery by conjugate gradient algorithm based on smoothing technique, Comput. Math. Appl., 66 (2013) 24--32
Electronic properties of GaAsBi(001) alloys at low Bi content
No full textWe present an in-depth investigation of structural and electronic properties of GaAsBi epilayers. High (001) crystalline order is achieved using careful molecular beam epitaxy and surface preparation procedures. High surface order allows us to use x-ray, ultraviolet, and angle-resolved photoemission spectroscopy at variable photon energies and to disentangle electronic effects of an atomically thin Bi-rich surface layer with (2 x 3) symmetry from those of Bi atoms incorporated in the GaAs bulk matrix. The influence of bulk-integrated Bi concentrations on the GaAs band structure becomes visible in angle-resolved photoemission after removing Bi-rich surface layers by a brief and mild ion bombardment and subsequent annealing treatment. Experimental observations are supported by density functional theory simulations of the valence band structure of bulk and surface-reconstructed GaAs with and without Bi. Bi-induced energy shifts in the dispersion of GaAs heavy and light hole bulk bands are evident both in experiment and theory, which are relevant for modulations in the optical band gap and thus optoelectronic applications
Evidence for Stable Sea-level during Marine Isotope Stage 5e of the Last Interglacial from the Western Mediterranean
No full textIMPROVING PREDICTION ACCURACY OF DEEP LEARNING FOR BRAIN CANCER DIAGNOSIS USING POLYAK-RUPPERT OPTIMIZATION
No full textAccurate and reliable diagnosis is critical for effective treatment planning for brain cancer. Recent advancements in deep learning have significantly enhanced diagnostic capabilities, but challenges persist in optimizing model performance for diverse and complex datasets. This study investigates the application of Polyak-Ruppert Optimization (PRO) to improve the prediction accuracy of conventional deep learning models for brain cancer diagnosis. Utilizing the REpository of Molecular BRAin Neoplasia DaTa (REMBRANDT) database, the proposed framework incorporates the advanced PRO technique to stabilize training and enhance generalization. The PRO’s impacts on convergence rates, model robustness, and predictive accuracy across multiple cancer types are analyzed. Experimental results demonstrate that VGG and ResNet models employing the PRO technique outperform the conventional architectures such as VGG and ResNet in classification metrics such as accuracy, sensitivity, and specificity. The potential of advanced optimization strategies such as PRO to refine deep learning applications in oncology paves the way for more accurate, efficient, and interpretable diagnostic systems
The 3He/4He Halo of the Kazbek Volcanic Center, Northern Caucasus
No full textManifestations of recent volcanism in the Greater
Caucasus are grouped in the El’brus and Kazbek volcanic
areas [1]. The last episodes of activity in the majority
of their eruptive centers date back to the Late
Holocene or even first centuries of the recent era
(El’brus Volcano) [2]. This implies potential volcanic
hazards in the Greater Caucasus. Therefore, it is important
to outline contours of this potentially hazardous
region with the maximal possible accuracy. The region
is characterized by indications of geodynamic stress,
such as recent eruptions, crustal deformations, seismic
activity, geothermal anomalies, and others. The 3He/4He value in natural gases can serve as one of such
indications.Published605–6083.2. Tettonica attivaJCR Journalreserve
Tuberculosis control in Jiangsu province, China
No full textPublished: April 26, 2016Li Yan, Zhu Limei, Cheng Chen, Lu Wei, Booker G.W, Yu Hao, and Polyak S.W
Spatially-localized time dependent solutions including turbulence and their interactions in 2D Kolmogorov flow
No full textIn 2D Kolmogorov flow in small aspect ratio domains, spatially-localized solutions such as kink, traveling or time-dependent kink-antikink pars coexist. However, the conservation of the flow rate in the y direction strongly restrict combination of localized solutions and their positioning. We find that by adding a homogeneous flow U y their positioning is controlled and each of localized solutions including a spatially-localized chaos is isolated. Numerical results suggest that these isolated solutions can be elements constructing a whole flow
Characteristics of overlap region in high-Reynolds number turbulent channel flow
No full textDirect numerical simulation of the fully developed turbulent channel flows have been carried out at the Reynolds number based on the friction velocity and the channel half width, 2000, 4000 and 8000. A hybrid 10th order accurate finite difference scheme in the stream and spanwise directions, and a second-order scheme in the wall-normal direction is adapted as the spatial discretization method. We observed the plateau profiles in the indicator function corresponded to the von Karman constant. Furthermore, second peak of streamwise pre-multiplied spectra were appeared in the same wall normal height, 300 < y+ < 600, in case of Re = 4000. Nevertheless, the effects of the lager than the channel half height scale on the streamwise turbulent intensity are fixed contributions without dependence on Reynolds number. These results suggested that the new streamwise vortexes are formed between buffer layer and outer layer with increasing of Reynolds number
La 'circunstancia' de 'Herederos y Pretendientes
No full textIn June 2010, the Ortega y Gasset Foundation hosted a Conference about the “Spanish Philosophical Transition” in order to debate the book of Francisco Vázquez, La filosofía española. Herederos y Pretendientes. Una lectura sociológica (1963-1990), recently published. This paper is the author’s response to criticism raised in the Conference and to published reviews received by this book. First, the author summarized the argument of Herederos y pretendientes. Secondly he responds and takes into account the most important objections against the book’s hypothesis and methodology. Finally the author evaluates the favorable judgments received by the book and suggests the limits of the historian’s task.Fundación Ortega y Gasset-Marañó
Author self-citation in orthodontics is associated with author origin and gender.
No full textBACKGROUND
The aims of this bibliometric study were to determine author self-citation trends in high-impact orthodontic literature and to investigate possible association between self-citation and publication characteristics.
METHODS
Six orthodontic journals with the highest impact factor as ranked by 2017 Journal Citation Reports were screened for a full publication year (2018) for original research articles, reviews, and case reports. Eligible articles were scrutinized for article and author characteristics and citation metrics. Univariable and multivariable negative binomial regression was used to examine associations between self-citation incidence and publication characteristics.
RESULTS
Medians for author self-citation rate of the most self-citing authors and self-citations were 3.03% (range 0-50) and 1 (range 0-19), respectively. In the univariable analysis, there was no association between self-citation counts and study type (P = 0.41), article topic (P = 0.61), number of authors (P = 0.62), and rank of authors (P = 0.56). Author origin (P = 0.001), gender (P = 0.001) and journal (P = 0.05) were associated with self-citation counts and in the multivariable analysis only origin and gender remained strong self-citation predictors. Asian authors and females self-cited significantly less often than all other regions and male authors.
CONCLUSIONS
Authors in orthodontics do not self-cite at a frequency that suggests potential citation manipulation. Author origin and gender were the only variables associated with citations counts. More bibliometric research is necessary to draw solid conclusions about author self-citation trends in orthodontic literature
- …
