An Anti Mode Mixing EMD Algorithm for Detecting the Characteristics of Low Frequency Oscillations in Power System

The dynamics of modern interconnected power system is characterized by low frequency oscillations (LFOs) which are produced as results of various disturbances such as changes in loads, tripping of lines, faults, and other discrete events. A data-driven empirical mode decomposition (EMD) method is applied to the detection of low frequency oscillation modes from disturbed trajectory with its strong non-stationary signal processing capability, but the mode mixing phenomenon serious impact on the analysis credibility and accuracy of EMD method. In this paper, an anti mode mixing EMD composite algorithm is proposed for detecting the characteristics of LFOs in power system. First, the improved frequency heterodyne method is proposed to increase the spectral distance between adjacent mode components in order to meet the octave resolution requirements. Second, the wavelet singularity detection technology is proposed to determine the adaptive sliding analysis window for each mode, in which there implements the intermittency mixed modes separation and their nonstationary parameters identification. Finally, the analysis result of interconnected grid test case verify that the proposed algorithm can effectively overcome the impact of the mode mixing existed in EMD and improve the characteristics detection accuracy of LFOs characteristics. DOI: http://dx.doi.org/10.11591/telkomnika.v11i8.3134

10-Formyl-2,4,6,8,12-penta­nitro-2,4,6,8,10,12-hexa­azatetra­cyclo­[5.5.0.03,11.05,9]dodeca­ne

The title compound, C7H7N11O11 (PNMFIW), is a caged heterocycle substituted with five nitro and one formyl groups. It is related to the hexa­azaisowurtzitane family of high-density high-energy polycyclic cage compounds. Four nitro groups are appended to the four N atoms of the two five-membered rings, while a nitro group and a formyl are attached to the two N atoms of the six-membered ring

A Study on the Implementation of Teaching Mathematical Modeling Classes Based on Mathematical Learning Objectives

Mathematical modeling literacy is one of the six core literacies in high school mathematics and occupies an important place in the objectives of the high school mathematics curriculum. “The core element of mathematical modeling literacy is to abstract mathematically from real problems, express them in mathematical language, and construct models to solve them with mathematical methods. The STEAM education concept has received much attention in the education field because of its effective integration of “science, technology, engineering, art and mathematics” in the practice of education and teaching, which not only makes up for the shortage of traditional teaching in knowledge inquiry, but also helps to improve the problems of traditional classrooms. This paper explores the development of mathematical modeling literacy in high school by drawing on the STEAM education concept, and examines the effectiveness of the integration of the two through specific teaching cases

An Asymptotic-Preserving and Energy-Conserving Particle-In-Cell Method for Vlasov-Maxwell Equations

In this paper, we develop an asymptotic-preserving and energy-conserving (APEC) Particle-In-Cell (PIC) algorithm for the Vlasov-Maxwell system. This algorithm not only guarantees that the asymptotic limiting of the discrete scheme is a consistent and stable discretization of the quasi-neutral limit of the continuous model, but also preserves Gauss's law and energy conservation at the same time, thus it is promising to provide stable simulations of complex plasma systems even in the quasi-neutral regime. The key ingredients for achieving these properties include the generalized Ohm's law for electric field such that the asymptotic-preserving discretization can be achieved, and a proper decomposition of the effects of the electromagnetic fields such that a Lagrange multiplier method can be appropriately employed for correcting the kinetic energy. We investigate the performance of the APEC method with three benchmark tests in one dimension, including the linear Landau damping, the bump-on-tail problem and the two-stream instability. Detailed comparisons are conducted by including the results from the classical explicit leapfrog and the previously developed asymptotic-preserving PIC schemes. Our numerical experiments show that the proposed APEC scheme can give accurate and stable simulations both kinetic and quasi-neutral regimes, demonstrating the attractive properties of the method crossing scales.Comment: 21 pages, 30 figure

4,10-Diformyl-2,6,8,12-tetra­nitro-2,4,6,8,10,12-hexa­azatetra­cyclo­[5.5.0.05,9.03,11]dodeca­ne

The title compound TNDFIW, C8H8N10O10, is a caged heterocycle substituted with four nitro and two formyl groups. It is related to the hexa­azaisowurtzitane family of high-density high-energy polycyclic cage compounds. Four nitro groups are appended to the four N atoms of the two five-membered rings, while the other two formyl groups are attached to the two N atoms of the six-membered ring, which adopts a boat conformation. The compound has a cage structure which is constructed from one six-membered and two five-membered rings which are closed by a C—C bond, thus creating two seven-membered rings. There are a number of close intermolecular contacts [O⋯O = 2.827 (5), 2.853 (4) and 2.891 (5) Å; O⋯N = 2.746 (2) and 2.895 (2) Å] The calculated density of TNDFIW is 1.891 Mg m−3

Association between atherogenic index of plasma and depression in individuals with different glucose metabolism status

BackgroundThe atherogenic index of plasma (AIP) has been implicated in various disease processes, yet its relationship with depression, particularly in the context of differing glucose metabolism status, remains underexplored. This study aimed to investigate the association between AIP and depression in middle-aged and older adults with varying glucose metabolism profiles.MethodsData were derived from the China Health and Retirement Longitudinal Study (CHARLS) conducted in 2011 and 2018, encompassing 7,723 participants aged 45 years and above. Depression was defined using a cutoff score of ≥12 on the 10-item Center for Epidemiologic Studies Depression Scale (CESD-10). The primary outcome of interest was incident depression. Logistic regression and restricted cubic spline (RCS) models were applied to assess the relationship between baseline AIP levels and depression risk across distinct glucose metabolism categories.ResultsElevated AIP was strongly associated with increased odds of depression. In fully adjusted models, a graded relationship was observed, with higher quartiles of AIP corresponding to greater depression risk. Participants in the highest AIP quartile (Q4) had significantly increased odds of depression (odds ratio [OR]: 3.36, 95% confidence interval [CI]: 2.67-4.24, P < 0.001) compared to those in the lowest quartile (Q1). Furthermore, RCS analyses revealed a significant positive association between AIP and incident depression among individuals with prediabetes mellitus (Pre-DM) and diabetes mellitus (DM) (P < 0.001), whereas no such association was found in participants with normal glucose regulation (NGR) (P = 0.086). These findings suggest that glucose metabolism status modifies the relationship between AIP and depression risk.ConclusionHigher baseline AIP levels are significantly associated with an increased risk of depression in middle-aged and older adults, with distinct effects modulated by glucose metabolism status. These results highlight the potential utility of AIP as a biomarker for depression risk and suggest that metabolic health should be considered in the development of targeted strategies for depression prevention and intervention

Preparation of Cementitious Material Using Smelting Slag and Tailings and the Solidification and Leaching of Pb 2+

The composite cementitious materials were prepared with lead-zinc tailings, lead-zinc smelting slag, and cement clinker. The effect of material ratio on the mechanical properties, the phase analysis, and microstructures were investigated. The effect of the pH and stripping time on the leaching amount of lead ion was discussed. The results show that the additive amount of the tailings should be minimized for the cementitious materials meeting the strength requirements, controlled within 10%. The leaching amount of cementitious materials remains low in a larger range of pH, which can effectively reduce the leaching of heavy metal lead. The leaching kinetics of lead ions in the three kinds of samples could be better described by the pseudo-second-model

FeGe1-xSbx:a series of novel kagome metals with noncollinear antiferromagnetism

Kagome metals are important for exploring emergent phenomena due to the interplay between band topology and electron correlation.Motivated by the recent discovery of charge density wave in a kagome lattice antiferromagnetic FeGe,we investigate the impact of Sb doping on the structural,charge and magnetic order of FeGe.The charge density wave is rapidly suppressed by Sb doping(~1.5%) and the antiferromagnetic ordering temperature gradually shifts to 280K for FeGe0.7Sb0.3.For FeGe1-xSbx with x>0.1,crystal structures with slightly distorted Fe kagome lattice are formed.Their magnetic anisotropy has significant change,temperature driven spin-reorientation and field-induced spin-flop transition are identified from magnetization measurement.Interestingly,neutron diffraction reveals noncollinear antiferromagnetic structures widely exist below TN for all sample with x>0.1.This noncollinear magnetic orders could possibly be unconventional and resulted from onsite repulsion and filling condition of kagome flat band,as predicted by a recent theoretical work