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Solvability of general backward stochastic Volterra integral equations
Yufeng Shi,Tianxiao Wang 대한수학회 2012 대한수학회지 Vol.49 No.6
In this paper we study the unique solvability of backward stochastic Volterra integral equations (BSVIEs in short), in terms of both the adapted M-solutions introduced in [19] and the adapted solutions via a new method. A general existence and uniqueness of adapted M-solutions is proved under non-Lipschitz conditions by virtue of a briefer argument than the ones in [13] and [19], which modifies and extends the results in [13] and [19] respectively. For the adapted solutions, the unique solvability of BSVIEs under more general stochastic non-Lipschitz conditions is shown, which improves and generalizes the results in [7], [14]and [15].
Shubin Zhang,Tianxiao Wang,Xin Guo,Shengwen Chen,Lijun Wang 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4
Sulfidated and bimetal modification can improve the reactivity and selectivity of zero-valent iron in contaminant removal. However, previous studies were focused on unilateral material approaches. In this article, a new hybrid composite Ag/S-ZVI was prepared by doping elemental silver on surface of sulfidated nanoscale zerovalent iron (S-nZVI). The results of X-Ray Diffraction (XRD), energy dispersive spectrometer (EDS) and X-ray Photoelectron Spectroscopy (XPS) indicated Ag was dispersed on the surface of S-nZVI. Scanning electron microscope (SEM) images displayed Ag/S-ZVI was irregular clusters with rough surfaces, small agglomeration, and quasi-spherical in shape. The removal of TCE by Ag/S-ZVI was 90.4% within 20 min. The reaction rate constant Kobs of Ag/S-ZVI was 2.59 times or 1.85 times of nZVI or S-nZVI, respectively. Cycling experiments showed that Ag/S-ZVI had good recycling ability, and the removal rate of TCE reached 72.6% at the third cycle. The addition of Ag+ makes S-nZVI as an abundant and efficient source of reducing electrons. The Fe<SUP>0</SUP> core can break C-Cl bonds by releasing electrons and the surface layer of Ag favors the transfer efficiency of electrons. Such study provides an efficient and robust ternary system for the remediation of TCE in groundwater.
SOLVABILITY OF GENERAL BACKWARD STOCHASTIC VOLTERRA INTEGRAL EQUATIONS
Shi, Yufeng,Wang, Tianxiao Korean Mathematical Society 2012 대한수학회지 Vol.49 No.6
In this paper we study the unique solvability of backward stochastic Volterra integral equations (BSVIEs in short), in terms of both the adapted M-solutions introduced in [19] and the adapted solutions via a new method. A general existence and uniqueness of adapted M-solutions is proved under non-Lipschitz conditions by virtue of a briefer argument than the ones in [13] and [19], which modifies and extends the results in [13] and [19] respectively. For the adapted solutions, the unique solvability of BSVIEs under more general stochastic non-Lipschitz conditions is shown, which improves and generalizes the results in [7], [14] and [15].
Sensitivity analysis of rolling bearing fatigue life under cyclic loading
Xianming Wang,Qingling Meng,Tianxiao Zhang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11
Rolling bearings are regularly subjected to cyclic loading, and the load changing sequence has a significant influence on bearing fatigue life. The study offers a cumulative fatigue damage theory based on the improved Lundberg-Palmgren method that takes into account the effect of load changing sequence on bearing fatigue life and then proposes a modified Miner bearing fatigue life model. Additionally, the state function for the bearing fatigue life analysis is developed based on the basic dynamic load rating and stress-strength interference model of the bearing. A moment-based sensitivity analysis method for bearing fatigue life is proposed for studying the influence of different variables on bearing fatigue life. Finally, a sensitivity analysis of the fatigue life of 6209 deep groove ball bearings was performed as an example. The calculation results demonstrate that the modified Miner life model is comprehensive and that the moment-based sensitivity analysis method is simple and accurate.
Inference on a structural break in trend with mildly integrated errors
Zhu Xu,Pang Tianxiao 한국통계학회 2022 Journal of the Korean Statistical Society Vol.51 No.1
In this paper, we study a regression model with a break in trend regressor, in which the model errors are assumed to be mildly integrated. To be precise, we suppose the model errors are generated by an AR(1) process with the autoregressive coefficient ρT=1+c/kT, where T is the sample size, c is a negative constant, and {kT,T∈N} is a sequence of positive constants diverging to infinity such that kT=o(T). We estimate the break date/break fraction and other parameters in the model using the least squares method. The asymptotic properties, including the consistency, rates of convergence as well as the limiting distributions, of the estimates are examined. The results derived in this paper bridge the findings in Perron and Zhu (Journal of Econometrics 129:65–119, 2005) who estimated the break date/break fraction in trend regressor under I(0) and I(1) model errors. We also show that the phase transition for the estimation error of the least squares estimate of the break date occurs when kT has the same order of magnitude as T1/2. Monte Carlo simulations and an empirical study are given to illustrate the finite-sample performance of estimates.
Racette Joshua,Walker Andrew,Nagasaki Shinya,Yang Tianxiao Tammy,Saito Takumi,Vilks Peter 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.10
The adsorption behaviour of Se(-II) onto granite and MX-80 bentonite in CaeNaeCl solutions has been studied utilizing adsorption experiments and surface complexation modelling. Adsorption kinetic experiments allude to steady-state adsorption periods after 7 days for granite and 14 days for MX-80 bentonite. Batch adsorption experiments were carried out to determine the influence that the physicochemical solution properties would have on Se(-II) adsorption behaviour. Adsorption of Se(-II) onto granite and MX-80 bentonite follows the trend of anionic adsorption, with a decrease in Rd values as the solution pH increased. There is also an ionic strength influence on the adsorption of Se(-II) onto granite with a decrease in the Rd value as the ionic strength increased. This effect is not found when observing Se(-II) adsorption onto MX-80 bentonite. Final experiments with a representative groundwater, determined that the adsorption of Se(-II) onto granite and MX-80 bentonite returned Rd values of (1.80 ± 0.10) m3kg1 and (0.47 ± 0.38) m3kg1, respectively. In support of the experiments, a surface complexation modelling approach has been employed to simulate the adsorption of Se(-II) onto granite and MX-80 bentonite, where it was determined that two different surface complexes, ≡S_Se and ≡SOH2 þ_H2Se were capable of simulating Se(-II) adsorption behaviour.
Chen Ting,Liu Pengfei,Liu Tianxiao,Li Xueyuan,Wang Huihui,He Tingwei,Liu Zhiyong 한국물리학회 2024 Current Applied Physics Vol.58 No.-
Electron transport layer (ETL) plays an important role in perovskite solar cells (PSCs). In this paper, a stable and cheap metal chelating agent, subnitrotriacetic acid (NTA), was used to modify SnO2 ETL in two ways:1) By incorporating NTA into SnO2 colloidal dispersion, the oxygen vacancy causing charge recombination was greatly reduced, and the recombination of psc was reduced by reducing the introduction of surface Ovs, 2) Spin-coating NTA at the SnO2/perovskite interface not only manages a large number of oxygen vacancies generated by high-temperature annealing, but also interacts with the unpaired Pb2+ in the perovskite absorption layer by interface modification of the C=O bond in NTA, passivates the surface of the perovskite layer, inhibits ion migration, stabilize the perovskite structure, and avoid its collapse, while significantly reducing the defect state density. By inhibiting the shallow interface trap and reducing the non-radiative recombination, efficient and stable perovskite solar cells were prepared. Under the condition of relative humidity greater than 40 % (RH), the efficiency of perovskite solar cells prepared by interface-anchored NTA was increased to 22.6 %, and the stability was significantly enhanced.
Sorption of Se(-II) on illite, MX-80 bentonite, shale, and limestone in Na – Ca – Cl solutions
Andrew Walker,Joshua Racette,Takumi Saito,Tammy (Tianxiao) Yang,Shinya Nagasaki 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.5
Selenium has been identified as an element of interest for the safety assessment of a deep geologicalrepository (DGR) for used nuclear fuel. In Canada, groundwaters at DGR depths in sedimentary rockshave been observed to have a high ionic strength. This paper examines the sorption behavior of Se(-II)onto illite, MX-80 bentonite, Queenston shale, and argillaceous limestone in NaeCaeCl solutions ofvarying ionic strength (0.1e6 mol/kgw (m)) and across a pH range of 4e9. Little ionic strength dependence for Se(-II) sorption onto all solids was observed except that sorption at high ionic strength (6 m)was generally slightly lower than sorption at low ionic strength (0.1 m). Illite and MX-80 exhibited theexpected results for anion sorption, while shale and limestone exhibited more constant sorption acrossthe pH range tested. A non-electrostatic surface complexation model successfully predicted sorption ofSe(-II) onto illite and MX-80 using the formation of an inner-sphere surface complex and an outer-spheresurface complex. Optimized values for the formation reactions of these surface species were proposed