The effects of agricultural activities and atmospheric acid deposition on carbonate weathering in a small karstic agricultural catchment, Southwest China

In order to quantify the sources and fluxes of DIC, the effects of the use of N-fertilizers and acid deposition on carbonate weathering have been quantified by hydrochemistry and δ13CDIC of groundwater in Qingmuguan underground river system (QURS) – a small karstic agricultural catchment of Southwest China. The results show that: (1) the significant temporal variations for major element concentrations and δ13CDIC of groundwater in different months were observed, especially, of which the groundwater showed significant high concentrations of DIC, Ca2+, Mg2+, NO3−, SO42− and δ13CDIC in rainy season and fertilizing period in the QURS; (2) the contributions of carbonate dissolution by carbonic acid to total concentrations of (Ca2++Mg2+) and HCO3− of groundwater in different months averaged 68.5 % and 81.0 %, respectively. While the contributions of carbonate dissolution by nitric acid originated from the use of N-fertilizers and atmospheric acid deposition to total concentrations of (Ca2++Mg2+) and HCO3− of groundwater in different months averaged 11.1 % and 6.7 %, respectively, and the contributions of carbonate dissolution by sulphuric acid originated from the atmospheric acid deposition to total concentrations of (Ca2++Mg2+) and HCO3− of groundwater in different months averaged 20.4 % and 12.3 %, respectively; (3) the δ13CDIC increased obviously with (Ca2++Mg2+)/HCO3− of groundwater in the rainy season and fertilizing period indicated that the use of N-fertilizers and atmospheric acid deposition should be responsible for the elevated the δ13CDIC and the molar ratio of (Ca2++Mg2+)/HCO3− of groundwater in the QURS.Key words: carbonate weathering, karst groundwater, agricultural activities, atmospheric acid deposition, Qingmuguan, Southwest China

Safety evaluation method of bridge plate rubber bearing based on SVM

In order to comprehensively evaluate the working state and safety performance of the bridge plate rubber bearing (PRB), the basic principle and method of SVM in machine learning theory (Support Vector Machine) was introduced in this paper. Firstly, the performance indices (such as the average compression stress, tangent value of the shear angle and the rotation angle of the PRB) were analyzed and calculated through its finite element model considering the different working conditions (axial compression, shear deformation and the rotation deformation of the PRB). Subsequently, considering the relevant indices affecting the safety performance of the PRB, the Pearson Correlation Coefficients (PCC) were calculated by SVM method for assessing the internal correlation of the performance indices of the PRB for different cases, respectively. The threshold values of the influential factors for different cases considering the PCC and the weight coefficient were obtained for grading the working state of the PRB as five levels. Moreover, in order to verify the validity and suitability of the evaluation of the working state of the plate rubber bearing by the SVM method, three apparent indices for grading the performance level of the PRB such as the crack, the undistributed spalling deformation and the dislocation of the PRB were analyzed and compared with the qualitative descriptions and the quantitative values. Finally, the corresponding threshold values for grading the performance levels of the PRB working states were proposed. It was shown that the SVM based evaluation method for the PRB is feasible and convenient, especially for the bridges with real-time monitoring devices to get the response data of the PRB

Linear convergence of the Collatz method for computing the Perron eigenpair of primitive dual number matrix

Very recently, Qi and Cui extended the Perron-Frobenius theory to dual number matrices with primitive and irreducible nonnegative standard parts and proved that they have Perron eigenpair and Perron-Frobenius eigenpair. The Collatz method was also extended to find Perron eigenpair. Qi and Cui proposed two conjectures. One is the k-order power of a dual number matrix tends to zero if and only if the spectral radius of its standard part less than one, and another is the linear convergence of the Collatz method. In this paper, we confirm these conjectures and provide theoretical proof. The main contribution is to show that the Collatz method R-linearly converges with an explicit rate.Comment: arXiv admin note: text overlap with arXiv:2306.16140 by other author

ELECRec: Training Sequential Recommenders as Discriminators

Sequential recommendation is often considered as a generative task, i.e., training a sequential encoder to generate the next item of a user's interests based on her historical interacted items. Despite their prevalence, these methods usually require training with more meaningful samples to be effective, which otherwise will lead to a poorly trained model. In this work, we propose to train the sequential recommenders as discriminators rather than generators. Instead of predicting the next item, our method trains a discriminator to distinguish if a sampled item is a 'real' target item or not. A generator, as an auxiliary model, is trained jointly with the discriminator to sample plausible alternative next items and will be thrown out after training. The trained discriminator is considered as the final SR model and denoted as \modelname. Experiments conducted on four datasets demonstrate the effectiveness and efficiency of the proposed approach.Comment: Accepted to SIGIR 202

The pc-scale radio structure of MIR-observed radio galaxies

We investigated the relationship between the accretion process and jet properties by ultilizing the VLBA and mid-infrared (MIR) data for a sample of 45 3CRR radio galaxies selected with a flux density at 178 MHz $>16.4$ Jy, 5 GHz VLA core flux density $\geq$ 7 mJy, and MIR observations. The pc-scale radio structure at 5 GHz are presented by using our VLBA observations for 21 sources in February, 2016, the analysis on the archival data for 16 objects, and directly taking the measurements for 8 radio galaxies available in literatures. The accretion mode is constrained from the Eddington ratio with a dividing value of 0.01, which is estimated from the MIR-based bolometric luminosity and the black hole masses. While most FRII radio galaxies have higher Eddington ratio than FRIs, we found that there is indeed no single correspondence between the FR morphology and accretion mode with eight FRIIs at low accretion and two FRIs at high accretion rate. There is a significant correlation between the VLBA core luminosity at 5 GHz and the Eddington ratio. Various morphologies are found in our sample, including core only, single-sided core-jet, and two-sided core-jet structures. We found that the higher accretion rate may be more likely related with the core-jet structure, thus more extended jet. These results imply that the higher accretion rates are likely able to produce more powerful jets. There is a strong correlation between the MIR luminosity at 15 $\mu$m and VLBA 5 GHz core luminosity, in favour of the tight relation between the accretion disk and jets. In our sample, the core brightness temperature ranges from $10^{9}$ to $10^{13.38}$ K with a median value of $10^{11.09}$ K indicating that systematically the beaming effect may not be significant....Comment: 21 pages, 8 figures, accepted by RA

An Alternative Approach for High Speed Railway Carrying Capacity Calculation Based on Multiagent Simulation

It is a multiobjective mixed integer programming problem that calculates the carrying capacity of high speed railway based on mathematical programming method. The model is complex and difficult to solve, and it is difficult to comprehensively consider the various influencing factors on the train operation. The multiagent theory is employed to calculate high speed railway carrying capacity. In accordance with real operations of high speed railway, a three-layer agent model is developed to simulate the operating process of high speed railway. In the proposed model, railway network agent, line agent, station agent, and train agent are designed, respectively. To validate the proposed model, a case study is performed for Beijing–Shanghai high speed railway by using NetLogo software. The results are consistent with the actual data, which implies that the proposed multiagent method is feasible to calculate the carrying capacity of high speed railway

Deciphering Charging Status, Absolute Quantum Efficiency, and Absorption Cross Section of MultiCarrier States in Single Colloidal Quantum Dot

Upon photo- or electrical-excitation, colloidal quantum dots (QDs) are often found in multi-carrier states due to multi-photon absorption and photo-charging of the QDs. While many of these multi-carrier states are observed in single-dot spectroscopy, their properties are not well studied due to random charging/discharging, emission intensity intermittency, and uncontrolled surface defects of single QD. Here we report in-situ deciphering the charging status, and precisely assessing the absorption cross section, and determining the absolute emission quantum yield of mono-exciton and biexciton states for neutral, positively-charged, and negatively-charged single core/shell CdSe/CdS QD. We uncover very different photon statistics of the three charge states in single QD and unambiguously identify their charge sign together with the information of their photoluminescence decay dynamics. We then show their distinct photoluminescence saturation behaviors and evaluated the absolute values of absorption cross sections and quantum efficiencies of monoexcitons and biexcitons. We demonstrate that addition of an extra hole or electron in a QD changes not only its emission properties but also varies its absorption cross section

Coexistence and compatibility of martensite reorientation and phase transformation in high-frequency magnetic-field-induced deformation of Ni-Mn-Ga single crystal

High-frequency magnetic-field-induced Martensite Reorientation (MR) is one of the most important advantages of Ferromagnetic Shape Memory Alloys (FSMAs), but its stability is threatened by dissipation heat accumulation (“self-heating”) of cyclic frictional twin boundary motion, which can cause temperature-induced Phase Transformation (PT) and reduce the output strain amplitude significantly. In this paper, the interaction of the temperature-induced PT and the magnetic-field-induced MR during high-frequency magnetic actuation on FSMA is studied with in-situ observations of local-strain evolution in conjunction with microstructure compatibility analysis. Based on the nominal strain and temperature responses and the corresponding local-strain maps, it is revealed that, when the temperature-induced PT takes place during the high-frequency field-induced MR, the specimen is divided into three zones: non-active austenite zone (with a constant deformation), active martensite zone (with cyclic deformations of MR) and buffering needle zone (interfacial zone) with a fine-needle-twin structure which plays an important role in maintaining the compatibility between austenite and martensite zones with different cyclic deformations during the dynamic loading. A novel mechanism is revealed that, under the magnetic actuation with changing ambient airflow, the “self-heating” temperature-driven phase boundary motion and the magnetic-field-driven twin boundary motion can coexist, because the specimen needs to self-organize the different phases/variants to satisfy all the thermo-magneto-mechanical boundary conditions. Taking advantage of this mechanism, the volume fractions of austenite and martensite zones can be adjusted with changing ambient airflow velocity, which provides an effective way to tune the nominal output strain amplitude (from 1% to 6% in the current study) while the working temperature is kept almost constant (around Ms and Mf)