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Wyświetlanie 1-6 z 6
Tytuł:
Theory II: Deep learning and optimization
Autorzy:
Poggio, T.
Liao, Q.
Powiązania:
https://bibliotekanauki.pl/articles/201787.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
deep learning
convolutional neural networks
loss surface
optimization
uczenie głębokie
sieć neuronowa
optymalizacja
Opis:
The landscape of the empirical risk of overparametrized deep convolutional neural networks (DCNNs) is characterized with a mix of theory and experiments. In part A we show the existence of a large number of global minimizers with zero empirical error (modulo inconsistent equations). The argument which relies on the use of Bezout theorem is rigorous when the RELUs are replaced by a polynomial nonlinearity. We show with simulations that the corresponding polynomial network is indistinguishable from the RELU network. According to Bezout theorem, the global minimizers are degenerate unlike the local minima which in general should be non-degenerate. Further we experimentally analyzed and visualized the landscape of empirical risk of DCNNs on CIFAR-10 dataset. Based on above theoretical and experimental observations, we propose a simple model of the landscape of empirical risk. In part B, we characterize the optimization properties of stochastic gradient descent applied to deep networks. The main claim here consists of theoretical and experimental evidence for the following property of SGD: SGD concentrates in probability – like the classical Langevin equation – on large volume, ”flat” minima, selecting with high probability degenerate minimizers which are typically global minimizers.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 6; 775-787
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel dynamical model for GVT nonlinear supporting system with stable-quasi-zero-stiffness
Autorzy:
Hao, Z.
Cao, Q.
Powiązania:
https://bibliotekanauki.pl/articles/279273.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
stable-quasi-zero-stiffness oscillator
optimization
bifurcation and chaos
Opis:
In this paper, a dynamical model of a spring-mass system with a single degree of freedom is proposed, which can be designed as a nonlinear supporting system for GVT of large scale aircraft and vibration isolation owing to stable-quasi-zero-stiffness (SQZS). The SQZS structure is constructed by a positive stiffness component and a pair of inclined linear springs providing negative stiffness, which is typical for an irrational restoring force due to geometrical configuration. The unperturbed analysis demonstrates complex equilibrium bifurcations and stabilities for this peculiar system, based upon which parameter optimizations are performed for SQZS and the maximum interval of low frequency. Furthermore, the dynamics analysis of the perturbed system near the optimized parameters reveals complicated behaviour of KAM structures, period doubling, chaos crisis, coexistence of multiple solutions, intermittency chaos, chaos saddle, etc. All those presented herein provide a better understanding for the complicated dynamics of SQZS nonlinear system.
Źródło:
Journal of Theoretical and Applied Mechanics; 2014, 52, 1; 199-213
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel Calix[4]arene network resin for Cr(VI) ions Remediation : A Response Surface Approach
Autorzy:
Siyal, A. N.
Memon, S. Q.
Powiązania:
https://bibliotekanauki.pl/articles/779157.pdf
Data publikacji:
2012
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
modified amberlite XAD-2
calixarene
cavities
network
optimization
remediation
removal
chromium
response surface methodology
factorial design
isotherms
Opis:
Novel Calix[4]arene Netwok (NCN) resin has been synthesized using Amberlite XAD-2 as the starting material. Hydroxyl groups have been introduced onto the para position of alkylated phenyl ring of Amberlite XAD-2 followed by the condensation to NCN by reacting it with formaldehyde. The NCN resin has been used for the remediation of Cr(VI) contaminated water using factorial design approach. A face-centered Draper-Lin composite design predicted ~100% removal effi ciency at optimum variables (the initial concentration of Cr(VI) ion 10 mg/l sorbent dose 200 mg, agitation time 136 min and pH 2). The accuracy and the fi tting of the model were evaluated by ANOVA and R2 (0.9992) values. The 99.5% removal effi ciency has been achieved experimentally at the optimum values of the variables. The Langmuir and D-R isotherm models were applicable to the sorption data with the value of RL and the sorption free energy 0.0057-0.1 and 7.93 kJ/mol respectively, suggesting favorable and physical/ion-exchange nature of the sorption. The calculated sorption capacity was 176.1š2.4 mg/g. The recycling studies of NCN resin showed that the multiple use of resin is feasible. Effect of concomitants has also been studies and proposed method was applied successfully for removal (98.7%) of Cr (VI) from electroplating wastewater.
Źródło:
Polish Journal of Chemical Technology; 2012, 14, 3; 21-28
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization and equilibrium studies of Pb(II) removal by Grewia Asiatica seed: a factorial design approach
Autorzy:
Siyal, A. N.
Memon, S. Q.
Khaskheli, M. I.
Powiązania:
https://bibliotekanauki.pl/articles/778329.pdf
Data publikacji:
2012
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
optymalizacja
usuwanie Pb(II)
odpady nasion Grewiii
metodologia powierzchni odpowiedzi
badania równowagi
biosorpcja
optimization
Pb(II) removal
Grewia seed waste
response surface methodology
factorial design
equilibrium studiem
biosorption
Opis:
This study aims to explore the efficiency of an agro waste material for the remediation of Pb(II) contaminated water. A factorial design approach is adopted to optimize removal efficiency and to study the interaction between effective variables. A face-centered Draper-Lin composite design predicted 100% removal efficiency at optimum variables; pH 8, initial concentration of Pb(II) ion 12mg/L, sorbent dose 200mg and agitation time 110 min. Regration coefficient (R2 = 99.9%) of a plot of the predicted versus the observed values and p value (>0.05) confirms the applicability of the predicted model. Langmuir and Dubinin-Radushkevich (D-R) isotherm models were applicable to sorption data with the Langmuir sorption capacity of 21.61š0.78 mg/g. The energy of sorption was found to be 13.62š0.32 kJ/mol expected for ion-exchange or chemisorption nature of sorption process. Characterization of Grewia seed suggested a possible contribution of carboxyl and hydroxyl groups in the process of biosorption. The present study shows that Grewia seeds can be used effectively for the remediation of Pb(II) contaminated water.
Źródło:
Polish Journal of Chemical Technology; 2012, 14, 1; 71-77
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Integrated design of observer based fault detection for a class of uncertain nonlinear systems
Autorzy:
Chen, W.
Khan, A, Q.
Abid, M.
Ding, S. X.
Powiązania:
https://bibliotekanauki.pl/articles/907595.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
detekcja uszkodzeń
obserwator
system nieliniowy
optymalizacja
odporność
fault detection
observer
nonlinear system
optimization
robustness
Opis:
Integrated design of observer based Fault Detection (FD) for a class of uncertain nonlinear systems with Lipschitz nonlinearities is studied. In the context of norm based residual evaluation, the residual generator and evaluator are designed together in an integrated form, and, based on it, a trade-off FD system is finally achieved in the sense that, for a given Fault Detection Rate (FDR), the False Alarm Rate (FAR) is minimized. A numerical example is given to illustrate the effectiveness of the proposed design method.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 3; 423-430
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-variant Sorption Optimization for the Uptake Of Pb(II) Ions by Jamun Seed Waste
Autorzy:
Siyal, A.N.
Memon, S.Q.
Amanullah, M.
Pirzada, T.
Parveen, S.
Powiązania:
https://bibliotekanauki.pl/articles/779346.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
optimization
Pb(II) ions removal
Jamun seed waste
response surface methodology
Factorial Design Approach
Opis:
In the present study, jamun seed waste has been explored for the removal of Pb(II) ions from aqueous solution. The multi-variant sorption optimization was achieved by the factorial design approach. 99.91% of Pb(II) ions was removed from aqueous solution. The results predicted by the model were in good agreement with the experimental results (the values of R2 and R2 adj. were found to be 99.89% and 99.95%, respectively). Langmuir and D-R isotherm studies were carried out to fi nd adsorbent's capacities (183.9 š 0.31 mg/g and 184.5 š 0.16 mg/g respectively), sorption free energy 13.17 š 0.16 and RL values in the range of 0.05-0.77, suggested the favorable chemical and/or ion exchange nature of the sorption process. The FT-IR study was carried out for unloaded and Pb(II) ions loaded jamun seed, indicated, Pb(II) ions associated with nitrogen and oxygen of jamun seed containing moieties during the adsorption process. The proposed method was successfully validated and applied for the treatment of Pb(II) ions contaminating drinking water.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 1; 15-21
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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