Second-order Core Research Articles

Compact Switched-Inductor Power Supplies: Design Optimization with Second-Order Core Loss Model

Expressing switched-inductor converter losses simply as a function of design variables is key for designers. Power losses in switched-inductor power supplies are varied in nature, and optimization schemes in the literature fail to account for all of them. Available core loss models are mostly empirical or rely on measurements or variables beyond the reach of power supply designers. Specifically, a simple core loss model is missing. This work offers complete design optimization of switched-inductor power supplies with a quadratic model of core loss that relies solely on design variables known to the designers—inductance and switching frequency (or inductor peak current). This model alleviates the burden of performing complex measurements to characterize the inductor—measurements that, moreover, require geometric data about the core, such as its size, which are often not disclosed by the manufacturer. Predicted minimum losses without approximation are within 3.2% of measured minimum losses, and predicted minimum losses with approximation are within 2.2% of measured minimum losses.

Nonparametric probabilistic forecasting based stochastic optimal scheduling of integrated electricity and gas systems

The volatility and sporadic availability of renewable energy create significant challenges to the optimal scheduling of integrated electricity and gas systems (IEGS). This paper develops a nonparametric probabilistic forecasting based stochastic scheduling approach of IEGS. The quantile at a series of quantile levels can be generated by direct quantile regression method. Given the set of predicted quantiles, a set of representative scenarios for wind power uncertainty can be obtained by using Monte Carlo simulation method and scenario reduction approach. Based on the implicit finite difference scheme, the original partial differential equations of the gas network are discretized to establish an algebraic model, which provide possibility for efficient solution. Then, the nonconvexity caused by the momentum equation is eliminated by the second-order core relaxation. Finally, the stochastic optimal scheduling model is reformulated as a second-order core programming problem. Numerical simulations are performed to showcase the superiority of the established stochastic optimal scheduling model.

Failure mode analysis and validation of hierarchical sandwich structures under compression

Based on the elastic thin plate theory, the mechanical properties and failure pattern are studied, considering the local failure defects, and the nominal positive stress expression of the hierarchical sandwich structures with a second-order core were presented. Moreover, the dominant relationship of each failure mode was compared, and the structure failure mechanism diagram is constructed by MATLAB, then the influence law of different local failure defects on the structure-dominant failure mode was discussed. However, for the failure mode of the structure, the emergence of the dominant failure mode of the secondary transmission path component may not be used as the failure criterion of the structure. Only when the failure mode of the structure appears on the main transmission path components, the failure mode can be used as the failure criterion of the hierarchical sandwich structure with a second-order core. In the failure mechanism diagram of the hierarchical sandwich structure with a second-order core, the single dominant failure mode of the structure can be accurately predicted, and for the junction of multiple mixed dominant failure modes, the structure is more prone to structural/component stability failure. At the same time, in order to test the correctness of the theoretical prediction, the verification experiment models were made with photosensitive resin 9000 material and 3D printing technology. Through the uniaxial compression test on the experimental model and numerical simulation, the correctness of the theoretical prediction of structural failure mode and ultimate bearing capacity is verified. The results show that the failure mode of the structure can be accurately predicted by the theoretical analysis, and the relative error is about 20% when calculating the bearing capacity. The experimental and simulation results agree well with the theoretical prediction.

Experimental Study on Failure Mechanism of Hierarchical Corrugated Structures with Second-order Core

Based on the sample experiment and ANSYS simulation, the experimental verification of the failure mode prediction model under compression load is completed, and the experimental results are compared with the theoretical analysis results. Among them, the sample experiment is carried out on the universal testing machine, including base metal experiment and uniaxial compression experiment. The experimental model is made of UV Curable Resin by 3D printing technology. And the buckling mode numerical simulation is completed on the ANSYS Workbench, using the plate and shell model of the pumping surface. By comparing the failure mode and yield stress of theory, experiment and simulation, the results show that the accuracy of the prediction model based on plate theory is higher. It can provide theoretical reference for structural design.

Failure behavior of hierarchical corrugated sandwich structures with second-order core based on Mindlin plate theory

For hierarchical corrugated sandwich structures with second-order core, the prediction error of failure behavior by existing methods becomes unacceptable with the increase of structure thickness. In this study, a novel analytical model called moderately thick plate model is developed based on Mindlin plate theory, which can be used to analyze the failure behavior of hierarchical corrugated structures with second-order core under compression or shear loads. Then, the analytical expressions of nominal stress for six competing failure modes are derived based on the moderately thick plate model. The results of six different unit structures based on the moderately thick plate model agree quite well the ones by finite element methods. Furthermore, the influence of different structure thicknesses is investigated to validate the applicability of the moderately thick plate model. According to the comparative results with the thin plate model, the proposed moderately thick plate model has a better precision with the increase of the ratio of thickness to width for failure components.

Relativistic description of second-order correction to nuclear magnetic moments with point-coupling residual interaction

Using the single particle states and the residual interaction derived from the relativistic point-coupling model with the PC-F1 parameter set, the second-order core polarization corrections to nuclear magnetic moments of LS closed shell nuclei ±1 nucleon with A = 15, 17, 39 and 41 are studied and compared with previous non-relativistic results. It is found that the second-order corrections are significant. With these corrections, the isovector magnetic moments of the concerned nuclei are well reproduced, especially those for A = 17 and A = 41.

An Analytic Center Cutting Plane Approach for Conic Programming

We analyze the problem of finding a point strictly interior to a bounded, convex, and fully dimensional set from a finite dimensional Hilbert space. We generalize the results obtained for the linear programming (LP), semidefinite programming (SDP), and second-order core programming (SOCP) cases. The cuts added by our algorithm are central and conic. In our analysis, we find an upper bound for the number of Newton steps required to compute an approximate analytic center. Also, we provide an upper bound for the total number of cuts added to solve the problem. This bound depends on the quality of the cuts, the dimensionality of the problem and the thickness of the set we are considering.

The influence of anthropogenic resources on multi-scale habitat selection by raccoons

With the continuing spread of urban areas, gaining a greater understanding of the effect of human presence on wildlife species is essential for wildlife managers. We determined the influence of anthropogenic resources on home range size and habitat selection of raccoons (Procyon lotor) during summer (June–August) 1996–2000 for 120 raccoons at three sites exposed to varying levels of urbanization and anthropogenic resources, specifically food. Home range estimates were larger (P < 0.05) at the rural site than the suburban and urban sites for both genders. We used compositional analysis to examine raccoon habitat selection at the second-order home range, second-order core area, and third-order home range scales. Woodland was consistently a highly-selected habitat type for both sexes at every spatial scale. Relative to other habitat types, habitat associated with human-related food (human use areas) was selected most often at the urban site, intermediately at the suburban site, and not selected at the rural site. Spatial scale also affected habitat selection. Human use areas were preferentially selected at the second- and third-order level at the urban site, third-order level only at the suburban site, and at neither level at the rural site. Additionally, intersexual differences in habitat selection were reduced at the urban site, with both sexes preferentially selecting for human use areas as well as woodland habitat. Smaller home ranges in urbanized environments are often attributed to the abundant and concentrated anthropogenic resources associated with human activity, but with little empirical support. Our habitat selection analyses followed our predictions that raccoon foraging is strongly influenced by the artificial distribution and abundance of human-related food. Male and female raccoons in urban areas reduce their foraging patterns and focus their foraging activity on anthropogenic foods.

Fabrication and Resonance Wavelengths of Long-Period Gratings Written in a Pure-Silica Photonic Crystal Fiber by the Glass Structure Change

It is shown that long-period gratings (LPGs) can be written in a pure-silica photonic crystal fiber without physical deformation by using the glass structure change. LPGs with different grating periods are made by the glass structure change induced by arc discharge. We find that the resonance wavelengths decrease with increasing the grating period in contrast with LPGs fabricated in conventional fibers. The second-order core mode begins to be supported in the long-wavelength region, and two resonance peaks appear there. This is due to a large increase of the index difference between the pure-silica core and the holey cladding against wavelength.

Electronic Band Structure of Monolayer Bi on GaP(110)

The two-dimensional electronic band structure of monolayer Bi on GaP(110) has been mapped using angle-resolved UV photoelectron spectroscopy (ARUPS) with synchrotron radiation. Surface photovoltage effects are corrected for by simultaneous second-order core spectroscopy. From valence-band spectra along the four symmetry directions of the surface Brillouin zone at three photon energies it is possible to distinguish three states as surface related. The topmost band is found to be inside the fundamental band gap, at ca 0.75 eV above the bulk valence-band maximum. Comparison with other V/III-V(110) systems shows that this system is not significantly different, despite the relatively large size of the Bi atoms with respect to the GaP lattice; in a selective comparison with InP and GaAs it would appear that Bi-substrate anion bonding is a more important factor than strain.

Core polarization effects on the magnetic form factors of15N and17O

The effects of the first- and the second-order core polarization on the elastic magnetic form factors of15N and17O are investigated using the perturbation theory based on the harmonic-oscillator shell model, in which for the matrix elements of the two-nucleon interaction the Sussex matrix elements are employed. The core polarization reduces the single-particle value ofM3 part of the form factor of17O, however the reduction of the form factor of15N does not lead to an improved agreement with experiment.

Transverse·inelastic form factor of the first excited state in 39K

A recent measurement of the transverse electron scattering form factor for the first excited state of 39K shows a significant departure from the single-particle picture of a pure d 3 2 − → 1 s 1 2 −1 proton transition. The data are well explained by a calculation including second-order core polarization and meson-exchange current corrections to both the M1 and E2 transition densities. These results are consistent with previous work on the elastic magnetic form factor, which also shows a significant departure from the extreme single-particle model.

Core polarization for l-forbidden M1 transitions in light nuclei

The experimental systematics of 2 s 1 2 ↔ ld 3 2 1- forbidden M1 transition rates in light nuclei with N, Z ≲ 20 are studied. Some surprising deviations from the expected behavior are qualitatively discussed in terms of an interplay between first- and second-order core polarization contributions. The B(M1) values in mirror pairs turn out to be close to each other within the experimental errors, the proton transition strengths being slightly larger. Isovector dominance is shown to account for this phenomenon.

RPA renormalisation of the effective interaction in a Hartree-Fock basis

Using a Hartree-Fock basis the diagrams of the Tamm-Dancoff and random-phase approximations have been summed to renormalise the effective interaction between two nucleons in the (1s0d) shell. The renormalisation effects are found to modify rather little the results obtained with the bare matrix elements. In particular the strong enhancement of the second-order core polarisation diagram which occur in an oscillator basis is found to be severely reduced in a Hartree-Fock basis.

Magnetic Moment of the Lowest 6+ State in 42Ca

The g -factor of the 3190 keV 6 + state in 42 Ca was measured by the time-differential perturbed-angular-distribution method in the 40 Ca(α,2 p ) 42 Ca reaction. The result is g =-(0.50 -0.03 +0.02 ). Assuming the 0.99f 7/2 2 +0.13f 7/2 f 5/2 configuration for the 6 + state, the magnetic moment for the 0f 7/2 neutron is deduced to be -1.99µ N , being very different from the known magnetic moment of the 41 Ca ground state. The strong violation of the additivity relation is interpreted by a larger mixing of the core-excited deformed states into the 41 Ca ground state. The above magnetic moment for the 0f 7/2 neutron supports recent proposal that the orbital g -factor is enhanced in nuclei by around 0.1 τ z if the quenching due to the second-order core polarization is taken into account.

Energy spectrum of 116Sn and effective nuclear forces derived from the realistic nucleon-nucleon potentials of Yale and of Tabakin

The effective nuclear forces are obtained by the core polarization renormalization from a realistic local static (Yale) and from a non-local (Tabakin) nucleon-nucleon potential. These forces are applied to the quasiparticle Tamm-Dancoff theory of the spectrum of 116Sn. While the respective bare (unrenormalized) forces lead to different predictions, the renormalized Yale and Tabakin effective forces yield almost identical results. While the second-order core polarization corrections are quite large. the successive inclusion of all the higher-order corrections (iteration) leads to only negligible modifications.