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| 1 | Exogenous rare earth element-yttrium deteriorated soil microbial community structure显示文摘In this study, we selected yttrium as the representative of REEs to investigate the impacts of exogenous yttrium on soil physicochemical properties and microbiota. The results showed that exogenous yttrium has no significant effect on soil physical properties but a significantly negative impact on soil chemical properties. The results of high-throughput sequencing demonstrate that exogenous yttrium significantly decreases the number of OTUs, ACE, Chao 1, and Shannon indices while increases the Simpson index(P < 0.05), indicating the low soil microbial diversity. The relative abundances of soil microbes are significantly changed at phylum and genus level. Principal component analysis(PCA) showed the significant difference of microbial community between yttrium treatments(YCl_3-250 and YCl_3-500) and non-yttrium treatment(CK) and the similarity of that between YCl_3-250 and YCI_3-500. Proteobacteria and Bacteroidetes are found to be the most tolerant phyla to exogenous yttrium while Verrucomicrobia the most sensitive phylum. Redundancy analysis(RDA) results suggest that exogenous yttrium affects soil microbiota only through changing the soil chemical properties but not soil physical properties, and C/N ratio is the key environmental factor. | Caigui Luo Yangwu Deng Jian Liang Sipin Zhu Zhenya Wei Xiaobin Guo Xianping Luo | 2018 | Journal of Rare Earths2018，36，4： | 5 |
| 2 | Convergence of Markov decision processes with constraints and state-action dependent discount factors显示文摘This paper is concerned with the convergence of a sequence of discrete-time Markov decision processes(DTMDPs)with constraints,state-action dependent discount factors,and possibly unbounded costs.Using the convex analytic approach under mild conditions,we prove that the optimal values and optimal policies of the original DTMDPs converge to those of the'limit'one.Furthermore,we show that any countablestate DTMDP can be approximated by a sequence of finite-state DTMDPs,which are constructed using the truncation technique.Finally,we illustrate the approximation by solving a controlled queueing system numerically,and give the corresponding error bound of the approximation. | Xiao Wu Xianping Guo | 2020 | Science China Mathematics2020，63，1： | 2 |
| 3 | Nonzero-sum games for continuous-time Markov chains with unbounded transition and average payoff rates显示文摘This paper attempts to study two-person nonzero-sum games for denumerable continuous-time Markov chains determined by transition rates,with an expected average criterion.The transition rates are allowed to be unbounded,and the payoff functions may be unbounded from above and from below.We give suitable conditions under which the existence of a Nash equilibrium is ensured.More precisely,using the socalled 'vanishing discount' approach,a Nash equilibrium for the average criterion is obtained as a limit point of a sequence of equilibrium strategies for the discounted criterion as the discount factors tend to zero.Our results are illustrated with a birth-and-death game. | ZHANG WenZhao GUO XianPing | 2012 | Science China Mathematics2012，55，11： | 2 |
| 4 | New optimality conditions for average-payoff continuous-time Markov games in Polish spaces显示文摘This paper concerns two-person zero-sum games for a class of average-payoff continuous-time Markov processes in Polish spaces.The underlying processes are determined by transition rates that are allowed to be unbounded,and the payoff function may have neither upper nor lower bounds.We use two optimality inequalities to replace the so-called optimality equation in the previous literature.Under more general conditions,these optimality inequalities yield the existence of the value of the game and of a pair of optimal stationary strategies.Under some additional conditions we further establish the optimality equation itself.Finally,we use several examples to illustrate our results,and also to show the difference between the conditions in this paper and those in the literature.In particular,one of these examples shows that our approach is more general than all of the existing ones because it allows nonergodic Markov processes. | GUO XianPing HERNNDEZ-LERMA Onsimo | 2011 | Science China Mathematics2011，54，4： | 2 |
| 5 | A minimization problem of the risk probability in first passage semi-Markov decision processes with loss rates显示文摘This paper is the first attempt to investigate the risk probability criterion in semi-Markov decision processes with loss rates. The goal is to find an optimal policy with the minimum risk probability that the total loss incurred during a first passage time to some target set exceeds a loss level. First, we establish the optimality equation via a successive approximation technique, and show that the value function is the unique solution to the optimality equation. Second, we give suitable conditions, under which we prove the existence of optimal policies and develop an algorithm for computing ?-optimal policies. Finally, we apply our main results to a business system. | HUANG XiangXiang ZOU XiaoLong GUO XianPing | 2015 | Science China Mathematics2015，58，9： | 2 |
| 6 | First passage Markov decision processes with constraints and varying discount factors显示文摘这份报纸与多限制,州依赖者的折扣因素,和可能无界的费用在可数的州、紧缩的 Borel 行动空格集中于分离时间的 Markov 决定处理的第一个段落(DTMDP ) 的抑制 optimality 问题(警察) 。借助于一条政策的一项所谓的职业措施的性质,我们证明抑制 optimality 问题等价于一(无限维) 职业的集合上的线性编程与一些限制测量,并且因此在合适的条件下面证明一条最佳的政策的存在。用在抑制 optimality 问题和线性编程之间的等价,而且,我们为有限状态和行动的盒子获得一条最佳的政策的一种准确形式。作为一个例子,最后,一个控制排队系统被给说明我们的结果。 | Xiao WU Xiaolong ZOU Xianping GUO | 2015 | Frontiers of Mathematics in China2015，10，4： | 2 |
| 7 | Seasonal variation in blood pressure and its relationship with outdoor temperature in 10 diverse regions of China: the China Kadoorie Biobank显示文摘 | Sarah Lewington Liming Li Paul Sherliker Yu Guo Iona Millwood Zheng Bian Gary Whitlock Ling Yang Rory Collins Junshi Chen Xianping Wu Shaojie Wang Yihe Hu Li Jiang Liqiu Yang Ben Lacey Richard Peto Zhengming Chen | 2012 | Journal of Hypertension2012，，7： | 1 |
| 8 | Monodisperse micro-spherical Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+)red phosphors显示文摘With narrow red photoluminescence (PL) bands, tetravalent Mn^(4+) doped phosphors show promising prospect in commercial application to effectively expand color gamut of phosphor converted LED displays. Here, we report a type of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) phosphors with regular cage-like micro-spherical morphologies. The micron size spherical precursors were synthesized with a propylene oxide (PO) driven fast sol–gel method. The cage -like spherical morphology is beneficial to efficiently trapping much incident light to enhance the PL of the phosphors. Being calcined at 1300 ℃, Sr_(2)MgAl_(21.978)O_(36):0.022Mn^(4+) only exhibits the internal quantum efficiency (IQE) of 24.91%. With the Mg^(2+)-Mn^(4+) codoping and Y^(3+)/Sr^(2+) substituting strategies, to fulfill charge balance and produce John-Teller distortion, IQE of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) can be further improved up to 36.45%. The CIE color coordinates of Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) under near ultraviolet excitation can be stably fixed to (0.723, 0.227) at deep red region. It thus finds a potential application as pc-LED display with much broader color gamut than that of the NTSC standard. Therefore, Sr_(2-z)Mg_(1+y)Y_(z)Al_(22-x)O_(36):xMn^(4+) micron size spheres can be employed as promising red phosphors for high performance LED displays. | Jiannan Jia Mengting He Jun Wan Yuting Zhang Hai Guo Xianping Fan Xusheng Qiao Shiguo Chen | 2022 | Journal of Rare Earths2022，40，4： | 1 |
| 9 | Fabrication and superconducting properties of nano-SiC doped MgB_2 tapes显示文摘Nano-SiC doped MgB2 tapes were prepared by the in situ powder-in-tube method. Heat treatment was performed at 650℃ for 1 h. XRD data indicate that SiC particles had reacted with the MgB2 during sintering process. MgB2 core seemed to be denser after SiC doping, and the critical temperature was slightly depressed. The critical current density Jc of the SiC doped tapes was significantly enhanced in magnetic fields up to 14 T compared to the undoped ones. For the 5% SiC doped samples, Jc was in- creased by a factor of 32 at 4.2 K, 10 T. The enhancement of Jc-B properties in SiC doped MgB2 tapes is considered to be due to the enhancement of grain linkages and the introduction of effective flux pining centers. The substitution of B by C in MgB2 grains is thought to be the main reason for the improve- ment of the flux pinning ability in SiC doped MgB2 tapes. | ZHANG XianPing MA YanWei GAO ZhaoShun YU ZhengGuang WANG DongLiang WATANABE K GUO JianDong | 2007 | Chinese Science Bulletin2007，52，18： | 0 |
| 10 | Correction to a proposition related to ergodicity of Markov chains显示文摘Proposition 5.5.6(ii)in the book Markov Chains and Stochastic Stability(2nd ed,Cambridge Univ.Press,2009)has been used in the proof of a theorem about ergodicity of Markov chains.Unfortunately,an example in this paper shows that this proposition is not always true.Thus,a correction of this proposition is provided. | Ziqi TAN Xianping GUO | 2021 | Frontiers of Mathematics in China2021，16，3： | 0 |
| 11 | STRONG N-DISCOUNT AND FINITE-HORIZON OPTIMALITY FOR CONTINUOUS-TIME MARKOV DECISION PROCESSES显示文摘This paper studies the strong n(n =—1,0)-discount and finite horizon criteria for continuoustime Markov decision processes in Polish spaces.The corresponding transition rates are allowed to be unbounded,and the reward rates may have neither upper nor lower bounds.Under mild conditions,the authors prove the existence of strong n(n =—1,0)-discount optimal stationary policies by developing two equivalence relations:One is between the standard expected average reward and strong—1-discount optimality,and the other is between the bias and strong 0-discount optimality.The authors also prove the existence of an optimal policy for a finite horizon control problem by developing an interesting characterization of a canonical triplet. | ZHU Quanxin GUO Xianping | 2014 | Journal of Systems Science & Complexity2014，27，5： | 0 |
| 12 | Optimal stopping time on discounted semi-Markov processes显示文摘This paper attempts to study the optimal stopping time for semi- Markov processes (SMPs) under the discount optimization criteria with unbounded cost rates. In our work, we introduce an explicit construction of the equivalent semi-Markov decision processes (SMDPs). The equivalence is embodied in the expected discounted cost functions of SMPs and SMDPs, that is, every stopping time of SMPs can induce a policy of SMDPs such that the value functions are equal, and vice versa. The existence of the optimal stopping time of SMPs is proved by this equivalence relation. Next, we give the optimality equation of the value function and develop an effective iterative algorithm for computing it. Moreover, we show that the optimal and ε-optimal stopping time can be characterized by the hitting time of the special sets. Finally, to illustrate the validity of our results, an example of a maintenance system is presented in the end. | Fang CHEN Xianping GUO Zhong-Wei LIAO | 2021 | Frontiers of Mathematics in China2021，16，2： | 0 |
| 13 | TOTAL REWARD CRITERIA FOR UNCONSTRAINED/CONSTRAINED CONTINUOUS-TIME MARKOV DECISION PROCESSES显示文摘这份报纸与期望的全部的报酬标准学习可数的连续时间的 Markov 决定过程。作者首先与可能的无界的转变率学习非强迫的模型,并且在作者在下面显示出全部的报酬 optimality 方程并且也的一个答案的存在的控制系统原语数据上给合适的条件一条最佳的静止政策的存在。然后,作者在期望的全部的费用上强加限制,并且考虑联系抑制模型。关于非强迫的模型并且用 Lagrange multipliers 途径基于结果,作者在一些另外的条件下面证明抑制最佳的政策的存在。最后,作者把结果用于控制排队系统。 | Xianping GUO Lanlan ZHANG | 2011 | Journal of Systems Science & Complexity2011，24，3： | 0 |
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