Robust Kalman filter-based dynamic state estimation of natural gas pipeline networks

To obtain the accurate transient states of the big scale natural gas pipeline networks under the bad data and non-zero mean noises conditions, a robust Kalman filter-based dynamic state estimation method is proposed using the linearized gas pipeline transient flow equations in this paper. Firstly, the dynamic state estimation model is built. Since the gas pipeline transient flow equations are less than the states, the boundary conditions are used as supplementary constraints to predict the transient states. To increase the measurement redundancy, the zero mass flow rate constraints at the sink nodes are taken as virtual measurements. Secondly, to ensure the stability under bad data condition, the robust Kalman filter algorithm is proposed by introducing a time-varying scalar matrix to regulate the measurement error variances correctly according to the innovation vector at every time step. At last, the proposed method is applied to a 30-node gas pipeline networks in several kinds of measurement conditions. The simulation shows that the proposed robust dynamic state estimation can decrease the effects of bad data and achieve better estimating results.Comment: Accepted by Mathematical Problems in Engineerin

New Dynamic Stability Rig for Tri-sonic Wind-tunnel

AbstractThe present-day unconventional and high-lifting aerospace configuration design has greatly increased the demand for accurate prediction and expanded measure dynamic stability derivatives envelopes of conventional aerospace vehicles. With these issues in mind, china academy of aerospace aerodynamics (CAAA) designed and built a forced oscillation test rig in the sub-, tran- and supersonic wind tunnel that provides new capabilities for aerodynamic researchers to accurately measure the dynamic derivatives and investigate the asymmetric coupling effects of high-lifting aerospace configuration vehicles

Specifying and verifying sensor networks: An experiment of formal methods

10.1007/978-3-540-88194-0-20Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)5256 LNCS318-33

Tetra­kis(μ-5-bromo­nicotinato)-κ3 O,O′:O′;κ3 O:O,O′;κ4 O:O′-bis­[diaqua­(5-bromo­nicotinato-κ2 O,O′)neodymium(III)] dihydrate

In the title compound, [Nd2(C6H3BrNO2)6(H2O)4]·2H2O, the NdIII ion is coordinated by nine O atoms from one chelating 5-bromo­nicotinate ligand, four bridging 5-bromo­nicotinate ligands and two water mol­ecules, exhibiting a distorted three-capped triangular-prismatic geometry. Two NdIII ions are bridged by four carboxyl­ate groups in bi- and tridentate modes, forming a centrosymmetric dinuclear unit, with an Nd⋯Nd distance of 4.0021 (5) Å, and intra­molecular π–π inter­actions between the pyridine rings [centroid–centroid distance = 3.960 (2) Å]. Inter­molecular π–π inter­actions [centroid–centroid distances = 3.820 (2) and 3.804 (2) Å] and O—H⋯N and O—H⋯O hydrogen bonds connect the dinuclear mol­ecules into a three-dimensional supra­molecular network

The Taiji-TianQin-LISA network: Precisely measuring the Hubble constant using both bright and dark sirens

In the coming decades, the space-based gravitational-wave (GW) detectors such as Taiji, TianQin, and LISA are expected to form a network capable of detecting millihertz GWs emitted by the mergers of massive black hole binaries (MBHBs). In this work, we investigate the potential of GW standard sirens from the Taiji-TianQin-LISA network in constraining cosmological parameters. For the optimistic scenario in which electromagnetic (EM) counterparts can be detected, we predict the number of detectable bright sirens based on three different MBHB population models, i.e., pop III, Q3d, and Q3nod. Our results show that the Taiji-TianQin-LISA network alone could achieve a constraint precision of $0.9\%$ for the Hubble constant, meeting the standard of precision cosmology. Moreover, the Taiji-TianQin-LISA network could effectively break the cosmological parameter degeneracies generated by the CMB data, particularly in the dynamical dark energy models. When combined with the CMB data, the joint CMB+Taiji-TianQin-LISA data offer $\sigma(w)=0.036$ in the $w$CDM model, which is close to the latest constraint result obtained from the CMB+SN data. We also consider a conservative scenario in which EM counterparts are not available. Due to the precise sky localizations of MBHBs by the Taiji-TianQin-LISA network, the constraint precision of the Hubble constant is expected to reach $1.2\%$. In conclusion, the GW standard sirens from the Taiji-TianQin-LISA network will play a critical role in helping solve the Hubble tension and shedding light on the nature of dark energy.Comment: 22 pages, 10 figures; published in Science China Physics Mechanics & Astronom

Event and strategy analytics

No Full Tex

Tetra­aqua­(nitrato-κ2 O,O′)bis­(pyridinium-4-carboxyl­ate-κO)europium(III) dinitrate

The asymmetric unit of the title compound, [Eu(NO3)(C6H5NO2)2(H2O)4](NO3)2, consists of one-half of the C 2 symmetric coordination cation and one nitrate anion. The eight-coordinated EuIII atom is in a distorted dodeca­hedral coordination environment. The coordination cations and nitrate anions are connected via O—H⋯O and N—H⋯O hydrogen bonds into a three-dimensional network

Involvement of AmphiREL, a Rel-like gene identified in Brachiastoma belcheri, in LPS-induced response: Implication for evolution of Rel subfamily genes

AbstractRel/NF-κB family genes are important transcriptional factors regulating vital activities of immunity response, but no Rel/NF-κB gene has been identified in amphioxus. In this study, we have not only identified and characterized a Rel-like gene from Brachiastoma belcheri, but also extensively studied the evolution of Rel gene subfamily. We found that: 1) the amphioxus genome contains an AmphiREL gene encoding a Rel/NF-κB homolog, and AmphiREL gene was involved in the innate immune response of LPS stimulation in amphioxus. 2) Gene synteny comparison and structure comparison suggested that AmphiREL is an orthologous gene of human RELB, and is a paralogous gene of human RELA and REL. 3) Structural changes of Rel subfamily proteins are diverse during the evolution process, and imply their functional diversity. 4) The Rel subfamily genes have undergone very strong purifying selection. Together, our results provide important clues for understanding the evolution and function of Rel subfamily genes

Power-Law Decay of Standing Waves on the Surface of Topological Insulators

We propose a general theory on the standing waves (quasiparticle interference pattern) caused by the scattering of surface states off step edges in topological insulators, in which the extremal points on the constant energy contour of surface band play the dominant role. Experimentally we image the interference patterns on both Bi$_2$Te$_3$ and Bi$_2$Se$_3$ films by measuring the local density of states using a scanning tunneling microscope. The observed decay indices of the standing waves agree excellently with the theoretical prediction: In Bi$_2$Se$_3$, only a single decay index of -3/2 exists; while in Bi$_2$Te$_3$ with strongly warped surface band, it varies from -3/2 to -1/2 and finally to -1 as the energy increases. The -1/2 decay indicates that the suppression of backscattering due to time-reversal symmetry does not necessarily lead to a spatial decay rate faster than that in the conventional two-dimensional electron system. Our formalism can also explain the characteristic scattering wave vectors of the standing wave caused by non-magnetic impurities on Bi$_2$Te$_3$.Comment: 4 pages, 3 figure