北京上空中小尺度电离层扰动特征

本文采用电离层测高仪数据对北京上空中小尺度电离层扰动进行了事例分析和统计研究.利用PDI电离层测高仪的快速扰动探测数据,分析了2017年11月13日北京上空典型的中小尺度电离层扰动事件.结果表明,电离层测高仪直接观测的电离层频高图上的V形(或U形)下降结构,是中等尺度电离层扰动的一种“显式”特征.小尺度电离层扰动主要出现于较低的高度,并不伴随着电离层频高图上显著的异常结构.通过统计2010—2021年电离层频高图数据中的电离层异常描迹事件,分析了北京上空中等尺度电离层扰动的发生率特征.以这些特殊描迹为特征的电离层扰动主要是白天现象,且冬季的发生率显著高于其他季节.其发生率与太阳活动呈反相关,即太阳活动较强时中等尺度电离层扰动的发生率较低,与地磁活动的相关性尚不十分明确.

高位巨厚砾岩对工作面开采地表沉降控制机理

为研究工作面开采后高位巨厚砾岩层对地表沉降的控制机理,以高庄煤矿西十一采区典型工作面为背景,采用理论分析、数值模拟、地表沉降实测等方法开展研究;基于微震事件分布分析了高位巨厚砾岩层工作面覆岩结构特征,高位巨厚砾岩层受采动影响较小,破坏程度较低;通过建立巨厚砾岩层Euler-Bernoulli固支裂缝梁力学模型,推导了裂缝影响下挠曲变形方程,阐明了巨厚砾岩层对地表沉降控制机理。数值模拟结果显示:覆岩垂直位移在巨厚砾岩层底部发生突变,巨厚砾岩层底部易产生离层空间,离层空间经历了“月牙”形、“盘”形形态演化,巨厚砾岩层影响下的模型地表沉降量明显较小。地表沉降实测结果显示:高位巨厚砾岩区工作面开采地表沉降量明显更小,高位巨厚砾岩对地表沉降具有明显的控制作用。

暴时低纬电离层不规则体响应特征的多手段观测

2010年10月11日发生了一次中等强度的磁暴.本文利用三亚(18.4°N,109.6°E)数字测高仪、VHF雷达和GPS TEC/闪烁监测仪数据以及120°E子午线附近我国漠河(53.5°N,122.4°E)、北京(40.3°N,116.2°E)和武汉(30.6°N,114.4°E)的数字测高仪和GPS TEC/闪烁监测仪数据,分析了磁暴期间我国中低纬地区电离层不规则体的响应特征.结果表明:这次磁暴触发了10月11日午夜前后两个时段低纬(三亚)电离层不规则体事件,而在较高的纬度地区(武汉及以北),并没有观测到电离层不规则体与闪烁.在午夜前,电离层不规则体的发生受磁暴主相期间快速穿透电场激发;在午夜后,电离层不规则体受磁暴恢复相的扰动发电机电场触发,该时段伴随行星际磁场北向翻转的过屏蔽穿透电场也可能是扰动源之一.此外,磁暴期间不同尺度的电离层不规则体会伴随发生.

CR-MMA乳液接枝共聚合

用乳液接枝法合成了氯丁橡胶（ＣＲ）－甲基丙烯酸甲酯（ＭＭＡ）接枝共聚物，并用喷雾干燥法制得了粉末状干胶。研究了氯丁二烯转化率、相对分子质量调节剂用量、残留氯丁二烯含量、接枝聚合温度、ＭＭＡ用量等对接枝共聚物溶解性和接枝率的影响。

氯丁二烯-二氧化硅杂化胶乳的制备(英文)

纳米二氧化硅的水分散液中直接乳液聚合得到的稳定的氯丁二烯-二氧化硅杂化胶乳。乳胶粒的粒径、ζ电位和透射电镜分析表明纳米二氧化硅吸附在氯丁胶乳粒子的表面。

绞车改造卡轨车在高煤公司掘进工作面的应用研究

简单介绍了新型卡轨车及适用掘进工作面的概况,重点介绍了设备硐室、适用巷道断面的设计、安装、应用情况及取得的经济、社会效益,在矿区掘进工作面的辅助运输方面具有较大的推广应用价值。

深部巷道群高静载低扰动冲击矿压发生机制及防治技术

针对深部巷道群高静载低扰动下突发性冲击矿压的难题,以某煤矿一盘区大巷为工程背景,通过力学分析和数值模拟研究了深部巷道群高静载低扰动诱发冲击矿压的发生机制。结果表明:大巷之间相互影响,导致巷道间煤柱区域应力叠加,高能量积聚在巷道顶底板内;巷道围岩蠕变使得围岩的长期强度降低,引起诱发冲击矿压的临界应力值降低,进而高静载水平下较小的动载扰动即可使叠加应力达到岩体承载极限,在能量达到岩体破坏的最小所需能量时,岩石产生自发性破坏,破坏后巷道围岩系统中的弹性余能转化为动能,造成巷道群冲击矿压发生。根据一盘区巷道群应力和能量分布区域和集中程度,采用大直径钻孔卸压和爆破卸压措施后,降低了应力和能量集中水平,卸压效果明显。

水性聚氨酯-氯丁二烯杂化胶乳的制备(英文)

在聚氨酯预聚体中加入氯丁二烯和少量甲基丙烯酸甲酯,经相反转分散到水相后聚合,制备了水性聚氨酯-氯丁二烯杂化胶乳,用傅里叶变换红外光谱对其进行了表征。结果表明,水性聚氨酯-氯丁二烯杂化胶乳的外观、粒径和ζ电位说明它是稳定的,杂化后的聚氨酯胶乳粒径增加、ζ电位降低。

断层破碎带煤巷围岩变形控制技术研究应用

针对山东能源集团有限公司高庄煤矿3上05材料巷掘进过程中受断层影响巷道大变形问题,分析了巷道变形特点及围岩结构破坏特征,认为断层构造区的复杂力学环境及破碎围岩结构是导致巷道变形显著的根本原因,提出强力锚注支护技术方案以加强断层破碎区的围岩控制,从改善围岩力学环境和承载能力两方面提升支护-围岩系统稳定性。现场监测数据表明:强力锚注技术的应用实现了对断层破碎区围岩的变形有效控制,巷道断面收敛量较小,扩散浆液改善了顶板围岩结构完整和承载性能,保障了巷道服务期间的生产安全。

煤矿综合机械化快速掘进技术研究

对于煤矿井工开采,巷道掘进成为回采的第一道工序。传统炮掘作业效率低,安全性差,容易发生灾害事故。因此,综合机械化快速掘进以其安全高效,巷道成型好的特点得到了广泛应用。本文通过讨论煤矿巷道快速掘进技术发展现状及趋势,以实际工程为背景,论述掘进机远程控制系统、技术参数等。通过远程控制掘进机进行掘进,实现了“机械换人”,改善了职工作业环境,达到了减员、降低劳动强度的效果,提高了掘进效率,巷道成型和稳定性良好,施工安全系数大大提高。

钠盐改性铝基高固水材料在矿山老巷充填治理中的适应性研究

针对工作面推采过老巷过程中面临的冲击地压、顶板管理等难题,研发了钠盐改性铝基高固水材料,可用于矿山井下老巷(空区)的充填治理。为探究该材料在矿山老巷原位充填治理中的适应性,采用室内试验、数值模拟、工程验证等方法,分析了该材料在老巷治理中的优势,给出了老巷在不同充填条件下围岩应力特征及变形破坏规律。研究表明:该材料单浆不凝固,混合料浆在4~15 min内初凝,1 d充填体强度可超过最终强度的70%,早强性明显、流动性好、密闭状态下充填体稳定性高、具有较高的固水性能;对老巷进行充填后,帮部煤体内应力峰值较未充填时降低,峰值位置向浅部转移,塑性区范围和围岩变形量减小;工程现场按水灰比8∶1进行充填,料浆输送距离超过1100 m,速凝性、早强性明显,充实率和接顶率高,冲击地压等各类灾害均得到有效控制,证明该材料可较好地适应于矿山废弃巷道治理。

Amplitude analysis of the decays D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)

Using e^(+)e^(−)annihilation data corresponding to an integrated luminosity of 2.93 fb^(−1)taken at the center-of-mass energy√s=3.773 GeV with the BESIII detector,a joint amplitude analysis is performed on the decays D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η).The fit fractions of individual components are obtained,and large interferences among the dominant components of the decays D^(0)→a_(1)(1260)π,D^(0)→π(1300)π,D^(0)→ρ(770)ρ(770),and D^(0)→2(ππ)_(S)are observed in both channels.With the obtained amplitude model,the CP-even fractions of D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η)are determined to be(75.2±1.1_(stat).±1.5_(syst.))%and(68.9±1.5_(stat).±2.4_(syst.))%,respectively.The branching fractions of D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η)are measured to be(0.688±0.010_(stat.)±0.010_(syst.))%and(0.951±0.025_(stat.)±0.021_(syst.))%,respectively.The amplitude analysis provides an important model for the binning strategy in measuring the strong phase parameters of D^(0)→4πwhen used to determine the CKM angleγ(ϕ_(3))via the B^(−)→DK^(−)decay.

Determination of the number ofψ(3686)events taken at BESⅢ

The number ofψ(3686)events collected by the BESⅢdetector during the 2021 run period is determined to be(2259.3±11.1)×10~6 by counting inclusiveψ(3686)hadronic events.The uncertainty is systematic and the statistical uncertainty is negligible.Meanwhile,the numbers ofψ(3686)events collected during the 2009 and 2012run periods are updated to be(107.7±0.6)×10~6 and(345.4±2.6)×10~6,respectively.Both numbers are consistent with the previous measurements within one standard deviation.The total number ofψ(3686)events in the three data samples is(2712.4±14.3)×10~6.

Observation of e^(+)e^(-)→pppñπ-+c.c.

Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢdetector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb^(-1),the process e^(+)e^(-)→pppñπ+c.c.is observed for the first time with a statistical significance of 11.5σ.The average Born cross sections in the energy ranges of(4.160,4.380)GeV,(4.400,4.600)GeV and(4.610,4.700)GeV are measured to be(21.5±5.7±1.2)fb,(46.3±10.6±2.5)fb and(59.0±9.4±3.2)fb,respectively,where the first uncertainties are statistical and the second are systematic.The line shapes of the pñ and ppπ^(-)invariant mass spectra are consistent with phase space distributions,indicating that no hexaquark or di-baryon state is observed.

Search for hidden-charm tetraquark with strangeness in e^(+)e^(−)→K^(+)D_(s)^(∗−) D^(∗0 )+ c.c.

We report a search for a heavier partner of the recently observed Z_(cs)(3985)^(-) state,denoted as Z_(cs)^('-),in the process e^(+)e^(−)→K^(+)D_(s)^(∗−) D^(∗0 )+ c.c.,based on e^(*)e^(-)collision data collected at the center-of-mass energies of √s=4.661,4.682 and 4.699 GeV with the BESIII detector.The Z_(cs)^('-) is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark.A partial-reconstruction technique is used to isolate K^(+)recoil-mass spectra,which are probed for a potential contribution from Z_(cs)^('-)→D_(s)^(∗−) D^(∗0 )+ c.c.We find an excess of Z_(cs)^('-)→D_(s)^(*-)-D^(*0)(c.c.)candidates with a significance of 2.1o,after considering systematic uncertainties,at a mass of(4123.5±0.7_(sat)±4.7_(syst.))MeV/c^(2).As the data set is limited in size,the upper limits are evaluated at the 90%confidence level on the product of the Born cross sections(σ^(Borm))and the branching fraction(B)of Z_(cs)^('-)→D_(s)^(*-)-D^(*0),under different assumptions of the Z_(cs)^('-) mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies.The upper limits of σ^(Born).B are found to be at the level of O(1)pb at each energy.Larger data samples are needed to confirm the Z_(cs)^('-) state and clarify its nature in the coming years.

Search for the weak decayψ(3686)→■+c.c.

Using(448.1±2.9)×10^(6)ψ(3686)for the weak baryonic decayψ(3686)→Λc+∑-+c.c..The analysis procedure is optimized using a blinded method.No significant signal is observed,and the upper limit on the branching fraction(B)ofψ(3686)→Λc+∑-+c.c.is set as 1.4×10^(-5)at the 90%confidence level.

Observations of the Cabibbo-Suppressed decays Λ_(c)^(+)→nπ+π^(0),nπ^(+)π^(-)π^(+) and the Cabibbo-Favored decay Λ_(c)^(+)→nK^(-)π^(+)π^(+)

Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb-1,collected by the BESⅢdetector in the energy region between 4599.53 MeV and 4698.82 MeV,we report the first observations of the Cabibbo-suppressed decaysΛ_(c)^(+)→nπ^(+)π^(0),Λ_(c)^(+)→nπ^(+)π^(-)π^(+),and the Cabibbo-favored decayΛ_(c)^(+)→nK^(-)π^(+)π^(+)with statistical significances of 7.9σ,7.8σ,and>10σ,respectively.The branching fractions of these decays are measured to be B(Λ_(c)^(+)→nπ^(+)π^(0))=(0.64±0.09±0.02)%,B(Λ_(c)^(+)→nπ^(+)π^(-)π^(+))=(0.45±0.07±0.03)%,and B(Λ_(c)^(+)→nK^(-)π^(+)π^(+))=(1.90±0.08±0.09)%,where the first uncertainties are statistical and the second are systematic.We find that the branching fraction of the decayΛ_(c)^(+)→nπ^(+)π^(0)is about one order of magnitude higher than that ofΛ_(c)^(+)→nπ^(+).

Testing Bell inequality at experiments of high energy physics

Besides using the laser beam, it is very tempting to directly testify the Bell inequality at high energy experiments where the spin correlation is exactly what the original Bell inequality investigates. In this work, we follow the proposal raised in literature and use the successive decays J/ψ →γηc→ ∧∧ → pπ^- pπ^＋ to testify the Bell inequality. Our goal is twofold, namely, we first make a Monte-Carlo simulation of the processes based on the quantum field theory （QFT）. Since the underlying theory is QFT, it implies that we pre-admit the validity of quantum picture. Even though the QFT is true, we need to find how big the database should be, so that we can clearly show deviations of the correlation from the Bell inequality determined by the local hidden variable theory. There have been some critiques on the proposed method, so in the second part, we suggest some improvements which may help to remedy the ambiguities indicated by the critiques. It may be realized at an updated facility of high energy physics, such as BES III.

Measurements of the center-of-mass energies at BESⅢ via the di-muon process

From 2011 to 2014, the BESIII experiment collected about 5 fb^-1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e＋e- →yma/Fsμ^＋μ^-, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking.

Measurement of cosmic ray flux in the China JinPing underground laboratory

The China JinPing underground Laboratory （CJPL） is the deepest underground laboratory running in the world at present. In such a deep underground laboratory, the cosmic ray flux is a very important and necessary parameter for rare-event experiments. A plastic scintillator telescope system has been set up to measure the cosmic ray flux. The performance of the telescope system has been studied using the cosmic rays on the ground laboratory near the CJPL. Based on the underground experimental data taken from November 2010 to December 2011 in the CJPL, which has an effective live time of 171 days, the cosmic ray muon flux in the CJPL is measured to be （2.0±0.4）×10^-10/（cm2.s）. The ultra-low cosmic ray background guarantees an ideal environment for dark matter experiments at the CJPL.