Modelling and Parameter Identification Using Reduced I-V Data

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Very short term irradiance forecasting using the lasso

We find an application of the lasso (least absolute shrinkage and selection operator) in sub-5-min solar irradiance forecasting using a monitoring network. Lasso is a variable shrinkage and selection method for linear regression. In addition to the sum of squares error minimization, it considers the sum of ℓ1-norms of the regression coefficients as penalty. This bias–variance trade-off very often leads to better predictions.<p></p> One second irradiance time series data are collected using a dense monitoring network in Oahu, Hawaii. As clouds propagate over the network, highly correlated lagged time series can be observed among station pairs. Lasso is used to automatically shrink and select the most appropriate lagged time series for regression. Since only lagged time series are used as predictors, the regression provides true out-of-sample forecasts. It is found that the proposed model outperforms univariate time series models and ordinary least squares regression significantly, especially when training data are few and predictors are many. Very short-term irradiance forecasting is useful in managing the variability within a central PV power plant.<p></p&gt

O(\alpha_s) QCD Corrections to Spin Correlations in e−e+→ttˉe^- e^+ \to t \bar t process at the NLC

Using a Generic spin basis, we present a general formalism of one-loop radiative corrections to the spin correlations in the top quark pair production at the Next Linear Collider, and calculate the O(\alpha_s) QCD corrections under the soft gluon approximation. We find that: (a) in Off-diagonal basis, the $O(\alpha_s)$ QCD corrections to $e_L^- e^+$ ($e_R^- e^+$) scattering process increase the differential cross sections of the dominant spin component $t_{\uparrow}\bar{t}_{\downarrow}$ ($t_{\downarrow}\bar{t}_{\uparrow}$) by $\sim 30$ and $\sim (0.1$ depending on the scattering angle for $\sqrt{s}=400 GeV$ and 1 TeV, respectively; (b) in {Off-diagonal basis} (Helicity basis), the dominant spin component makes up 99.8% ($\sim 53$) of the total cross section at both tree and one-loop level for $\sqrt{s}=400 GeV$, and the Off-diagonal basis therefore remains to be the optimal spin basis after the inclusion of $O(\alpha_s)$ QCD corrections.Comment: 12 pages, 4 figures, revised version (a few print mistakes are corrected, some numerical results are modified, and Fig.4 is added

Probing dark particles indirectly at the CEPC

When dark matter candidate and its parent particles are nearly degenerate, it would be difficult to probe them at the Large Hadron Collider directly. We propose to explore their quantum loop effects at the CEPC through the golden channel process $e^+e^-\to \mu^+\mu^-$. We use a renormalizable toy model consisting of a new scalar and a fermion to describe new physics beyond the Standard Model. The new scalar and fermion are general multiplets of the $SU(2)_L\times U(1)_Y$ symmetry, and couple to the muon lepton through Yukawa interaction. We calculate their loop contributions to anomalous $\gamma\mu^+\mu^-$ and $Z\mu^+\mu^-$ couplings which can be applied to many new physics models. The prospects of their effects at the CEPC are also examined assuming a 0.002 accuracy in the cross section measurement

A linear method to extract diode model parameters of solar panels from a single I–V curve

The I-V characteristic curve is very important for solar cells/modules being a direct indicator of performance. But the reverse derivation of the diode model parameters from the I-V curve is a big challenge due to the strong nonlinear relationship between the model parameters. It seems impossible to solve such a nonlinear problem accurately using linear identification methods, which is proved wrong in this paper. By changing the viewpoint from conventional static curve fitting to dynamic system identification, the integral-based linear least square identification method is proposed to extract all diode model parameters simultaneously from a single I-V curve. No iterative searching or approximation is required in the proposed method. Examples illustrating the accuracy and effectiveness of the proposed method, as compared to the existing approaches, are presented in this paper. The possibility of real-time monitoring of model parameters versus environmental factors (irradiance and/or temperatures) is also discussed

Permanent Deformation of Earth Dam Due to Earthquake

This paper combines the equivalent nodal force method suggested by serf et al, (1976) and equivalent inertial force method proposed by Taniguchi et al (1983, 1987). The former is fine to utilize seed\u27s strain potential but the stress-strain curve is obtained only by static test, while the latter uses dynamic stress-strain curve, but the determination of direction of equivalent inertial force is rather difficult. The writers use the equivalent nodal force by average shear stress (τav=0.65 τmax) and assume it\u27s direction to be coincided with static shear stress. Also dynamic stress-residual shear strain curve is obtained by dynamic testing