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Identifying the key N species for electrocatalytic oxygen reduction reaction on N-doped graphene

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Nano Research 2023年第5期16卷 6642-6651页

作者： Yiyin Peng Zhaoyong Bian wenhai zhang Hui Wang College of Water Sciences Beijing Normal UniversityBeijing 100875China College of Environmental Science and Engineering Beijing Forestry UniversityBeijing 100083China

The state of nitrogen in nitrogen-doped graphene(NG)promoting the conversion of molecular oxygen to hydrogen peroxide was *** oxygen reduction reaction(ORR)reactivity of graphitic-N,pyrrolic-N,pyridinic-N in NG was predicted by density functional theory(DFT).A series of NG samples with different contents of these doped nitrogen types were prepared by the low-temperature thermal reduction method and used for the ORR *** H_(2)O_(2)yield,2e−ORR current efficiency,H_(2)O_(2)selectivity,electron transfer number(n)were systematically *** 2e−ORR selectivity was positively correlated with the N content,approaching 100%with increasing N content(0.40 V *** hydrogen electrode(RHE)),whereas the comparative energy efficiency showed a volcano-type trend related to N content,reaching a maximum of 94%.In addition,N species validation experiments proved the key role of pyrrolic-N in the synthesis of H_(2)O_(2).Compared with a pure graphene catalyst,further contaminant degradation studies on NG electrodes with different pyrrolic-N contents revealed that the lower pyrrolic-N the higher removal of p-nitrophenol(PNP).This work provides insight into the mechanism of ORR on metal-free catalysts and a facile approach to optimize this important environmental catalytic strategy.

关键词： oxygen reduction electrocatalysis nitrogen-doped graphene environmental remediation

Multicopy quantum state discrimination

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Science China(Physics,Mechanics & Astronomy) 2012年第1期55卷 60-65页

作者： zhang wenhai YU LongBao YANG Ming ZhuoLiang Department of Physics Huainan Normal University Huainan 232038 China Department of Physics and Electronic Engineering Hefei Teachers College Hefei 230061 China School of Physics and Material Science Anhui University Hefei 230039 China

In this paper, we study the problem of multicopy quantum two-state discrimination. By exploring the quantum hypothesis testing, i.e., the probabilisfic quantum cloning, we derive the upper bounds of the minimal error discrimination （MED） and the optimal unambiguous discrimination （OUD）, which coincides with the Helstrom theorem and the JS limit. Furthermore, when prior probabilities are unknown, we derive the minimax MED and the minimax OUD. Based on the optimal NM probabilistic quantum cloning, we present the optimal strategies of collective measurements of the MED and the OUD. When the number of the copies is infinite, regardless of whether prior probabilities are known or not, the success probabilities of the MED and the OUD go to 100%, in accordance with the quantum measurement hypothesis that unknown quantum state can be determined if and only if infinite identical quantum state copies are given.

关键词： quantum state discrimination Helstrom theorem JS limit minimal error discrimination (MED) optimal unambiguousdiscrimination (OUD)

A Nowcasting Technique Based on Application of the Particle Filter Blending Algorithm

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Journal of Meteorological Research 2017年第5期31卷 931-945页

作者： yuanzhao chen hongping lan xunlai chen wenhai zhang meteorological bureau of shenzhen municipality Shenzhen 518040 shenzhen key laboratory of severe weather in south china Shenzhen 518040 shenzhen academy of severe storm science Shenzhen 518040

To improve the accuracy of nowcasting, a new extrapolation technique called particle filter blending was con- figured in this study and applied to experimental nowcasting. Radar echo extrapolation was performed by using the radar mosaic at an altitude of 2.5 km obtained from the radar images of 12 S-band radars in Guangdong Province, China. The first bilateral filter was applied in the quality control of the radar data; an optical flow method based on the Lucas-Kanade algorithm and the Harris corner detection algorithm were used to track radar echoes and retrieve the echo motion vectors; then, the motion vectors were blended with the particle filter blending algorithm to estimate the optimal motion vector of the true echo motions; finally, semi-Lagrangian extrapolation was used for radar echo extrapolation based on the obtained motion vector field. A comparative study of the extrapolated forecasts of four precipitation events in 2016 in Guangdong was conducted. The results indicate that the particle filter blending al- gorithm could realistically reproduce the spatial pattern, echo intensity, and echo location at 30- and 60-min forecast lead times. The forecasts agreed well with observations, and the results were of operational significance. Quantitat- ive evaluation of the forecasts indicates that the particle filter blending algorithm performed better than the cross-cor- relation method and the optical flow method. Therefore, the particle filter blending method is proved to be superior to the traditional forecasting methods and it can be used to enhance the ability of nowcasting in operational weather forecasts.

关键词： radar echo particle filter blending bilateral filter semi-Lagrangian extrapolation nowcasting

Quantum cloning with multicopy in d-dimensions

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Science China(Physics,Mechanics & Astronomy) 2011年第12期54卷 2217-2224页

作者： zhang wenhai YU LongBao YANG Ming CAO ZhuoLiang Department of Physics Huainan Normal University Huainan 232038 China Department of Physics and Electronic Engineering Hefei Teachers College Hefei 230061 China School of Physics and Material Science Anhui University Hefei 230039 China

The explicit transformations of the 1→ 3 optimal universal quantum cloning and the optimal phase-covariant quantum cloning in d-dimensions are presented, and the dimensionalities of their ancillary systems are both d-dimensions. As d→∞ , their clone fidelities move toward 1/3, showing a classical limit for the fidelity of quantum cloning. Based on the reduction of the unitary transformation of quantum cloning, the transformation of the 1→M=d+1 optimal economical phase-covariant quantum cloning in d-dimensions is derived, and the clone fidelity is covered by the theoretical value.

关键词： quantum cloning universal quantum cloning phase-covariant quantum cloning economical phase-covariant quantum cloning

Optical scheme for realization of optimal unambiguous state discrimination of the JS limit

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Science China(Physics,Mechanics & Astronomy) 2013年第3期56卷 606-609页

作者： zhang wenhai YU LongBao CAO ZhuoLiang YE Liu Department of Physics Huainan Normal University Department of Physics and Electronic Engineering Hefei Normal University School of Physics and Material Science Anhui University

We exploit optimal probabilistic cloning to rederive the JS *** on the formulation given by the optimal probabilistic cloning,the explicit transformation of a measure of the JS limit is *** on linear optical devices,we propose an experimentally feasible scheme to implement the JS limit measure of a general pair of two nonorthogonal quantum *** success probability of the proposed scheme is unity.

关键词： quantum state discrimination optimal unambiguous discrimination JS limit optimal probabilistic quantum cloning

温敏型胶体对玉米淀粉3D打印固化性能的影响

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食品工业科技 2023年第9期44卷 45-52页

作者：张文海农业农村部冷冻调理水产品加工重点实验室福建厦门361022

目的:利用温敏型胶体的相转变特性,辅助实现淀粉在打印过程中的成型固化,并揭示不同种类胶体-淀粉体系的固化性能变化规律。方法:将不同比例的温敏型胶体(低酰基结冷胶、明胶、κ-卡拉胶)与玉米淀粉进行复配并测定其流变性能,通过打印... 详细信息

目的:利用温敏型胶体的相转变特性,辅助实现淀粉在打印过程中的成型固化,并揭示不同种类胶体-淀粉体系的固化性能变化规律。方法:将不同比例的温敏型胶体(低酰基结冷胶、明胶、κ-卡拉胶)与玉米淀粉进行复配并测定其流变性能,通过打印圆柱及空心球模型、测试产品力-位移曲线、温度扫描流变、全质构分析及微观结构观测评估体系可打印及固化性能。结果:结冷胶和卡拉胶在2%~4%添加量,明胶在0%~2%添加量时,体系具有适宜的流变性能及良好的可打印性能。添加4%结冷胶及4%卡拉胶的产品表现出显著的塑性,固化效果较好;添加明胶的打印产品无显著塑性,打印产品不固化。结冷胶-淀粉混合体系的固化温度在35~43℃之间;卡拉胶-淀粉混合体系的固化温度在30~40℃之间,随着胶体含量增加,固化温度上升,固化速度加快。而随着明胶含量增加,固化温度从25℃下降至20℃以下且固化速度减慢。4%低酰基结冷胶产品具有更致密的凝胶网络,硬度高于4%κ-卡拉胶产品。明胶对硬度、弹性都有削弱作用,但使粘附力大幅提高。结论:适宜含量的低酰基结冷胶和κ-卡拉胶能够实现淀粉的成型固化,且卡拉胶固化性能优于结冷胶,而明胶则无辅助固化能力。

关键词：温敏型胶体玉米淀粉 3D打印成型固化可打印性

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给定不确定结果的量子比特的量子态区分

中山大学学报（自然科学版） 2015年第1期54卷 52-56,63页

作者：张刚张文海皖西学院机械与电子工程学院安徽六安237012 淮南师范学院物理系安徽淮南232038

给出更简单的利用辅助测量比特和系统的幺正演化的方法用于在给定不确定结果时的量子比特的两个量子态区分。方案涵盖了当不确定结果的概率为零时的最小错误区分,以及当不确定结果的概率为某些数值时的最优确定性区分。文中给出最大全... 详细信息

给出更简单的利用辅助测量比特和系统的幺正演化的方法用于在给定不确定结果时的量子比特的两个量子态区分。方案涵盖了当不确定结果的概率为零时的最小错误区分,以及当不确定结果的概率为某些数值时的最优确定性区分。文中给出最大全局正确概率和给定不确定概率关系的解析式。利用辅助测量比特,对被测的非正交量子态初态系统实施幺正演化,对输出态进行正交测量,就可以完成非正交态的量子态区分。方案提供了一种对于两个非正交量子态的正定算符值测量的物理实现方法。

关键词：量子态区分最小错误区分确定性区分

Optical scheme for realization of optimal unambiguous state discrimination of the JS limit

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Science China Chemistry 2013年第3期56卷 606-609页

关键词： quantum state discrimination optimal unambiguous discrimination JS limit optimal probabilistic quantum cloning

基于台区变压器二次侧电压变化的配电网故障区段定位

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电力系统保护与控制 2022年第16期50卷 23-32页

作者：张耘浩张姝张文海肖先勇四川大学电气工程学院四川成都610065

随着配电网精品台区的建设,越来越多的监测装置向台区低压侧延伸,为配电网的故障定位提供了新的思路。提出了一种基于台区变压器二次侧电压变化的配电网故障区段定位方法。分析了配电网发生故障后的台区变压器侧的电压变化规律,利用故... 详细信息

随着配电网精品台区的建设,越来越多的监测装置向台区低压侧延伸,为配电网的故障定位提供了新的思路。提出了一种基于台区变压器二次侧电压变化的配电网故障区段定位方法。分析了配电网发生故障后的台区变压器侧的电压变化规律,利用故障路径与非故障路径下监测点三相电压幅值变化差异辨识故障区段。通过采用改进的最近邻聚类法,在电压监测集合中辨识出距离故障不同位置的监测点集,能够对监测信息进行快速的分区。该方法不需要10 kV线路的监测数据,仅需要配电台区10 kV/0.4 kV变压器低压侧电压幅值变化信息,监测采集装置安装维护方便。通过大量仿真表明,该方法能够适应不同中性点的接地方式、故障类型和过渡电阻,具有较强的适用性。

关键词：配电网电压监测装置故障区段定位变电站二次侧改进的近邻聚类法