mlsa-iai-msu-lab/ru_sci_bench_zho_cite_reranking huggingface dataset:
Carbon-doping-induced negative differential resistance in armchair phosphorene nanoribbons

By using a combined method of density functional theory and non-equilibrium Green’s function formalism, we investigate the electronic transport properties of carbon-doped armchair phosphorene nanoribbons(APNRs). The results show that C atom doping can strongly affect the electronic transport properties of the APNR and change it from semiconductor to metal. Meanwhile, obvious negative differential resistance(NDR)behaviors are obtained by tuning the doping position and concentration. In particular, with reducing doping concentration, NDR peak position can enter into mV bias range. These results provide a theoretical support to design the related nanodevice by tuning the doping position and concentration in the APNRs.
Identification and analysis of intermediate-size noncoding RNAs in the rhesus macaque fetal brain

Although only about 2% of the human genome has proved to be protein-coding genes, recent advances in genome wide analysis have revealed that the majority of the genome is transcribed, mainly from noncoding segments that were once considered “junk sequences” or “dark matters” (Liu et al., 2011a; Zhang et al., 2014b). In addition to the well-characterized housekeeping noncoding RNAs (ncRNAs) (tRNA, rRNA, small nuclear RNA and small nucleolar RNAs) and some small regulatory ncRNAs (microRNAs and small interfering RNAs), the transcriptome of mammals could also pervasively have been transcribed long noncoding RNAs (lncRNAs, at least 200 nt) (Rinn and Chang, 2012; Xie et al., 2012). Studies of lncRNAs have become very common and extensive recently, but research on intermediate-size noncoding RNAs (isncRNAs), with lengths ranging from 50 to 500 nt, is not yet so systematic. Fewstudies have been reported about is-ncRNAs, although they have been identified to be functional in development of many organisms and shown to play important roles in transcriptional regulation, DNA damage responses, and tumorigenesis (Deng et al., 2006; Xu et al., 2010; Zhang et al., 2010; Yan et al., 2011; Wei et al., 2014). We are even able to ascertain the potential functions of is-ncRNAs through systematic high-throughput sequencing and concordant analysis. Rhesus macaque (Macaca mulatta), a widely-used model animal for primate and clinical studies, can be used for drug and viral infection tests. Evolutionary sequence comparisons between rhesus monkeys and humans can provide potential targets for exploring novel functional genes and clinical molecular markers (Blekhman et al., 2010; Liu et al., 2011b). The complete description of the rhesus monkey transcriptome enhances the utility of this animal model in both basic and clinical research studies (Zhang et al., 2014a).
Novel insights into the role of NF-κB p50 in astrocytemediated fate specification of adult neural progenitor cells

Within the CNS nuclear factor-kappa B (NF-κB) transcription factors are involved in a wide range of functions both in homeostasis and in pathology. Over the years, our and other groups produced a vast array of information on the complex involvement of NF-κB proteins in different aspects of postnatal neurogenesis. In particular, several extracellular signals and membrane receptors have been identified as being able to affect neural progenitor cells (NPC) and their progeny via NF-κB activation. A crucial role in the regulation of neuronal fate specification in adult hippocampal NPC is played by the NF-κB p50 subunit. NF-κB p50KO mice display a remarkable reduction in adult hippocampal neurogenesis which correlates with a selective defect in hippocampal-dependent short-term memory. Moreover absence of NF-κB p50 can profoundly affect the in vitro proneurogenic response of adult hippocampal NPC (ahNPC) to several endogenous signals and drugs. Herein we briefly review the current knowledge on the pivotal role of NF-κB p50 in the regulation of adult hippocampal neurogenesis. In addition we discuss more recent data that further extend the relevance of NF-κB p50 to novel astroglia-derived signals which can influence neuronal specification of ahNPC and to astrocyte-NPC cross-talk.
产前超声联合MRI诊断先天性右肺中间支气管闭锁一例临床分析

综上所述,胎儿LBA是发生在肺叶支气管的闭锁,临床上极其罕见,超声表现为一侧肺明显肿大,回声均匀增强,肺内支气管可见扩张而气管不扩张。心脏受压移向对侧,膈肌反向,如伴发腹腔积液及羊水过多往往提示预后不良,产前超声联合MRI可提高诊断准确率。
超声弹性成像技术在深静脉血栓分期中应用的研究进展

下肢深静脉血栓(deep venous thrombosis,DVT)是临床常见疾病,其治疗原则与血栓的分期息息相关,目前,缺乏准确的血栓分期评估方法。随着超声弹性成像技术的迅猛发展,其在评估血栓分期中的价值日益受到人们的重视。
A novel model to assess soil productivity in the dry-hot valleys of China

Accurate evaluation of soil productivity has been a long-standing challenge. Although numerous models for productivity assessment exist, most are cumbersome to use and require substantial parameter inputs. We developed a new empirical soil productivity model based on field investigations of soil erosion, soil physicochemical properties, and crop yields in the dry-hot valleys (DHVs) in China. We found that soil pH, and organic matter and available potassium contents significantly affected crop yields under eroded conditions of the DHVs. Moreover, available potassium content was the key factor affecting soil productivity. We then modified an existing soil productivity model by adding the following parameters: contents of effective water, potassium, organic matter, and clay, soil pH, and root weighting factor. The modified soil productivity model explained 63.5% of the crop yield. We concluded that the new model was simple, realistic, and exhibited strong predictability. In addition to providing an accurate assessment of soil productivity, our model could potentially be applied as a soil  module in comprehensive crop models.
Evolution of Specialization with Reachable Transaction Scope Based on a Simple and Symmetric Firm Resource Allocation Model

In the last decade, as an emerging transaction measure driven by computer and internet technology, e-commerce experienced explosive growth in many areas. It has greatly broken down the limitations of space and time to economic activities, thus changing the rules of business fundamentally. Significant work has been done to understand the laws of e-commerce from multiple dimensions, but the question of how e-commerce shapes firms’ specialization and market structure from the perspective of spatial factors remains obscure. In this paper, we propose a simple and symmetric firm resource allocation model with a specialized-economy production function and market size constraint, to investigate how individual firms adjust resource allocation with reachable transaction scope expanded. It is shown that with the expansion of reachable transaction scope, individual firms discretely take back one unit resource from a low-investment direction and, instead, channel it to a “specialized direction”. Meanwhile, at the macro level, an optimal division network evolves from a static self-sufficient stage to a diverse semi-specialized stage, and finally to a highly integrated completely specialized stage. Ergo, a Complex Adaptive System (CAS) based simulation framework is constructed. Designed simulation experiments are carried out and confirm to the analysis result of our proposed model.
Distributed and Weighted Extreme Learning Machine for Imbalanced Big Data Learning

The Extreme Learning Machine (ELM) and its variants are effective in many machine learning applications such as Imbalanced Learning (IL) or Big Data (BD) learning. However, they are unable to solve both imbalanced and large-volume data learning problems. This study addresses the IL problem in BD applications. The Distributed and Weighted ELM (DW-ELM) algorithm is proposed, which is based on the MapReduce framework. To confirm the feasibility of parallel computation, first, the fact that matrix multiplication operators are decomposable is illustrated. Then, to further improve the computational efficiency, an Improved DW-ELM algorithm (IDW-ELM) is developed using only one MapReduce job. The successful operations of the proposed DW-ELM and IDW-ELM algorithms are finally validated through experiments.
北方杂交粳稻保持系产粉量研究

选用辽宁省稻作研究所目前使用的具有代表性的11个保持系辽39B、辽31B、辽111B、辽1B、辽52B、辽99B、辽秀B、辽90B、辽121B、辽91B、辽95B等为试验材料,研究不同保持系的单个花药体积和花粉量的差异,以及花药体积与花粉量的相关性。结果表明:辽52B花药体积最大,产粉量最高;辽31B花药体积最小,产粉量最少;单个花药体积与产粉量极显著正相关。筛选花药体积大的保持系,可以显著增加保持系的花粉量,增加父本田间花粉密度,从而提高杂交粳稻不育系的繁种产量。
连续阴雨天气对杂交水稻结实率的影响与危害

对泸州市2015年6月末—7月初出现的连续阴雨天气对多个杂交水稻品种结实率的影响和危害做了分析,提出了防范阴雨天气对杂交水稻品种结实率危害的措施和建议。
Safe growth of graphene from non-flammable gas mixtures via chemical vapor deposition

Chemical vapor deposition has emerged as the most promising technique for the growth of graphene. However, most reports of this technique use either flammable or explosive gases, which bring safety concerns and extra costs to manage risk factors. In this article, we demonstrate that continuous monolayer graphene can be synthesized via chemical vapor deposition technique on Cu foils using industrially safe gas mixtures. Important factors, including the appropriate ratio of hydrogen flow and carbon precursor, pressure, and growth time are considered to obtain graphene films. Optical measurements and electrical transport measurements indicate graphene films are with comparable quality to other reports. Such continuous large area graphene can be synthesized under non-flammable and non-explosive conditions, which opens a safe and economical method for mass production of graphene. It is thereby beneficial for integration of graphene into semiconductor electronics.
In Situ Synthesis of Core-Shell Li_4Ti_5O_(12)@Polyaniline Composites with Enhanced Rate Performance for Lithium-ion Battery Anodes

The core-shell Li_4Ti_5O_(12)@polyaniline composites(LP)have been synthesized via an in situ synthesis with different mole ratios(25:1, 50:1 and 100:1, aniline:LTO).As an anode material of lithium-ion batteries, the LP-2 electrodes(50:1)exhibit a high initial reversible capacity of 205 mAh g~(-1) with an initial coulombic efficiency of 97.6% at 0.1 C.Even at a high current density of 10 C, the reversible capacity of the LP-2 electrodes still remains at 102 mAh g~(-1).Moreover, the LP-2 electrodes retain an impressive high capacity of 161 mAh g~(-1) after 100 cycles at 1 C, with 0.11% capacity fading per cycle.The promising electrochemical performance may be attributed to the significantly decreasing charge-transfer impedance of the LP composite and reductive polarity difference between the cathode and the electrolyte.
妊娠晚期瘢痕子宫不全破裂12例临床分析

目的:探讨妊娠晚期瘢痕子宫不全破裂患者的原因及诊断和治疗。方法:对12例妊娠晚期瘢痕子宫不全破裂患者的临床资料进行回顾性分析。结果: 12例均有剖宫产史,无先兆子宫破裂典型症状,1 0例患者仅表现为子宫下段压痛。孕晚期B超检查子宫下段最薄处约0. 4 ~ 3. 3 mm,大于2. 5 mm 4例。所有病例在剖宫产术中确诊,均采取再次剖宫产终止妊娠, 12例母婴均存活良好。结论:瘢痕子宫不全破裂临床症状不典型,仅靠临床病史及体征难以诊断,需结合B超动态监测。一旦疑似瘢痕子宫不全破裂,应行剖宫产终止妊娠。
新产程的产房安全专题讨论-新产程指南面临的挑战

2010年,张军( Zhang)等进行了一项大规模基于大数据的回顾性研究,采用了不同于Friedman时代的数据处理方法,发表了当代美国孕妇的产程标准,颠覆了临床应用五十多年的Friedman产程图,见表1[1]。在张军等的研究推动下,美国为了降低不断攀升的剖宫产率,特别是初次剖宫产率,2012年美国国家儿童健康与人类发展研究所( NICHD) 、美国妇产科医师学会( ACOG)以及美国母胎医学学会( SMFM)发表评论文章“Current Commentary: Preventing the First Cesarean Delivery (避免初次剖宫产) ”[2]。2014年 ACOG和SMFM联合发表的专家共识“ACOG/SMFM Obstetric Care Consensus: Safe prevention of the primary cesarean delivery(安全避免初次剖宫产) ”诞生[3],该专家共识明确了潜伏期延长( prolonged latent phase)的剖宫产指征、活跃期的起始点、活跃期停滞( active phase arrest) 、第二产程延长( second stage arrest) 、引产失败( failed induction of labor)的定义。这些变化引发全球产科界广泛关注。
1型进行性家族性肝内胆汁淤积症患儿的护理

总结1例1型进行性家族性肝内胆汁淤积症患儿的护理,护理要点包括瘙痒的护理,饮食管理,用药护理,疲乏的护理,健康教育及心理护理等。患儿住院10 d,病情稳定出院。
L型鼻贴在长期留置鼻肠管患者鼻部皮肤保护中的应用

目的探讨L型鼻贴在长期留置鼻肠管患者鼻部皮肤保护中的应用效果。方法将50例普外科长期留置鼻肠管的患者随机分为观察组(25例)和对照组(25例),观察组交替使用圆角鼻贴及L型鼻贴固定鼻肠管,对照组使用圆角鼻贴固定鼻肠管,两组均每5天更换鼻贴1次。结果对照组与观察组均无鼻肠管脱出发生,鼻肠管移位率分别为4.00%、8.00%,鼻肠管移位率差异无统计学意义(P>0.05),观察组鼻部皮肤刺激发生率显著低于对照组,患者舒适度显著高于对照组(均P<0.01)。结论L型鼻贴可有效减少皮肤刺激的发生率,提高患者舒适度。
择期手术患者术前转运时头部朝向的探讨

目的探讨择期手术患者术前转运时头部体位的朝向对其心率、血压及舒适度的影响。方法选择行择期手术的患者120例, 随机分为头部朝前组(A组)和头部朝后组(B组)各60例,A组根据患者的年龄将18~60岁划为A1组,>60岁划为A2组2个亚组各30例,B组按相同的方法分为B1组与B2组各30例。在控制各组转运过程中病床行驶速度保持一致的情况下,记录患者在转运前、转运后(即到达手术室时)的心率、血压,并记录患者此次转运过程的舒适度。结果四组患者转运后心率较转运前均显著增快(P<0.05);转运前后血压变化无显著差异;四组患者转运过程的舒适度及下次转运的朝向选择比较,差异无统计学意义(均P>0.05);93.3%患者对于下次转运时的转运方向表示无所谓。结论术前转运时患者的头部朝向对患者的舒适度无显著影响,心率增快可能与患者心理紧张有关,需在转运过程中进行心理护理。
Thermal stability, mechanical properties and corrosion behavior of a Mg–Cu–Ag–Gd metallic glass with Nd addition

By the minor addition of Nb to a Mg–Cu–Ag– Gd alloy, a Mg–Cu–Ag–Gd–Nb bulk metallic glass (BMG) with improved thermal stability and corrosion resistance as well as good mechanical properties was developed. Mg_(54)Cu_(26.5)Ag_(8.5)Gd_(11-x)Nb_x (x = 0, 1) BMGs with a diameter of 2 mm were fabricated by copper-mold casting. The Mg_(54)Cu_(26.5)Ag_(8.5)Gd_(10)Nb_1 BMG exhibits enlarged supercooled liquid region of 58 K. Electrochemical measurements indicate that the addition of Nb improves the corrosion resistance of the Mg-based BMG in NaCl solution evidenced by the increased corrosion potential, though no significant effect of Nb on the corrosion behavior of the BMG in NaOH solution is observed. The Mg–Cu–Ag–Gd– Nb BMG also shows high compressive strength up to 890 MPa and elastic strain of about 1.9%.
Magnetic properties and special morphology of barium ferrite via electrospinning

Barium ferrite micro-/nanofibers with special morphology, nanowires with diameters of 100 nm, nanoribbons with diameters of 1 lm, and nanotubes with outer diameter of about 300 nm while inner diameter of 100 nm were successfully prepared via electrospinning using different solvents (dimethyl formamide (DMF), solutions of deionized water and ethyl alcohol, and solutions of deionized water and acetic acid, respectively). The barium ferrite micro-/nanofibers were characterized by scanning electron microscope (SEM), X-ray diffraction analysis (XRD), and vibration sample magnetometer (VSM). The results demonstrate that the pure BaFe_(12)O_(19) ferrite phase is successfully formed. And the SEM results show excellent morphologies. The magnetic hysteresis loops demonstrate that their magnetic properties are quite different with different morphologies. The specific saturation magnetization is approximately the same (46.12–49.17 A·m~2·kg~(-1)), but the coercivity of the BaFe_(12)O_(19) increases from wires (190.08 kA·m~(-1)), ribbons (224.16 kA·m~(-1)) to tubes (258.88 kA·m~(-1)).
Extranodal involvement in young patients with diffuse large B-cell lymphoma: distribution, prognostic value and treatment options

Objective: Extranodal involvement represents a peculiar presentation of diffuse large B-cell lymphoma(DLBCL). Previous studies have suggested that older patients are more prone to extranodal involvement. This study retrospectively addressed the distribution, prognostic value and treatment options of extranodal involvement in young patients with DLBCL. Methods: A total of 329 patients were enrolled according to the inclusion requirements. The effects of gender, extranodal involvement, age-adjusted international prognostic index(aaIPI), rituximab infusion and radiotherapy on patient outcomes were evaluated. Results: Among these patients, 59% presented extranodal involvement in 16 anatomic sites. More than one instance was linked to many poorer clinical characteristics and poorer survival compared with either nodal disease or one instance. In patients with one extranodal lesion, multivariate analysis revealed that the site of extranodal involvement, but not the aaIPI or rituximab infusion, was independently related to the outcome, and radiotherapy had a negative influence on survival. Conclusions: Extranodal involvement is common in younger patients and exhibits a ubiquitous distribution. The site of extranodal involvement is of strong prognostic significance. Radiotherapy for extranodal lesions does not improve patient outcomes.
MAGI1 inhibits migration and invasion via blocking MAPK/ERK signaling pathway in gastric cancer

Objective: To explore the association of membrane-associated guanylate kinase inverted 1(MAGI1)with gastric cancer(GC)and the related molecular mechanisms. Methods: The reverse transcription-polymerase chain reaction(RT-PCR)and immunohistochemistry(IHC)were utilized to measure the MAGI1 expression level in GC tissues. Quantitative real-time PCR and Western blotting were used to ensure the MAGI1 expression in GC cell lines. Small hairpin RNA(shRNA)was applied for knockdown of endogenous MAGI1 in GC cells. MTT assay and colony formation assay, scratch wounding migration assay and transwell chamber migration assay, as well as transwell chamber invasion assay were employed respectively to investigate the GC cell proliferation, migration and invasion in MAGI1-knockdown and control GC cells. The potential molecular mechanism mediated by MAGI1 was studied using Western blotting and RT- PCR. Results: RT-PCR and IHC verified MAGI1 was frequently expressed in matched adjacent noncancerous mucosa compared with GC tissues and the expression of MAGI1 was related to clinical pathological parameters. Functional assays indicated that MAGI1 knockdown significantly promoted GC cell migration and invasion. Further mechanism investigation demonstrated that one pathway of MAGI1 inhibiting migration and invasion was mainly by altering the expression of matrix metalloproteinases(MMPs)and epithelial-mesenchymal transition(EMT)- related molecules via inhibiting MAPK/ERK signaling pathway. Conclusions: MAGI1 was associated with GC clinical pathological parameters and acted as a tumor suppressor via inhibiting of MAPK/ERK signaling pathway in GC.
Structures and electrochemical performances of as-cast and spun RE-Mg-Ni-Mn-based alloys applied to Ni-MH battery

The RE-Mg-Ni-Mn-based AB_2-type La_(1-x)Ce_xMgNi_(3.5)Mn_(0.5) (x=0-0.4) alloys were prepared by spinning treatment. For obtaining the optimum performance, the effects of Ce content and spinning rate on the hydrogen storage performance of the alloys were studied systematically. The results show that the variations of the spinning rate and Ce content result in noteworthy changes of the phase content without altering phase composition of the alloys. Specifically, the LaMgNi_4 phase increases and LaNi_5 phase decreases when increasing the spinning rate and Ce content. Furthermore, the crystalline grains of Ce-containing alloys prepared by spinning treatment are remarkably refined. The alloys own superior electrochemical performance. All alloys reach the optimal discharge capacity at the initial cycle. Increasing Ce content and spinning rate lead the discharge capacity and electrochemical kinetics rise to an optimal value and then start to reduce. Meanwhile, the electrochemical cycle stability is also improved, which is ascribed to the great enhancement of anti-pulverization and anti-corrosion abilities resulting from the spinning treatment and the substitution of Ce for La.
永磁同步力矩电机转矩波动分析建模研究

永磁同步力矩电机以其高转矩密度、响应快速、无中间传递环节等特点,在数控机床和仿真转台等需要直接驱动、运行平稳、快速响应和高精度的控制系统中得到了越来越多的应用。但其转矩的波动对系统产生了很大的影响,降低了控制精度。首先对永磁同步力矩电机的工作原理进行分析,建立在不同坐标系下的数学模型。然后借助MATLAB/Simulink和基于SVPWM的直接转矩控制对系统各子环节进行建模分析,最后将分析结果与实验结果进行对比,得到了理论与实际相一致的结果。
新工业革命背景下制造业管理模式研究与创新

围绕新一轮产业革命,加强制造业管理模式研究与创新,引领生产方式和服务模式变革,对于加快制造强国建设具有重要战略意义。分析了新工业革命背景下企业战略管控、组织形态变革、数据价值挖掘等方面管理创新关键点,总结了我国产业界以管理创新孕育新模式新业态的探索与实践,可为制造业管理模式创新提供有益借鉴。
不同过盈量对零件装配影响的有限元分析

装配是机械产品生产过程中一个必不可少的环节,过盈装配时由于存在过盈量而产生的应力对装配好的机构性能有比较大的影响,严重时可能会造成机构的破坏。为此,应用有限元软件ABAQUS对不同过盈量的装配进行有限元分析,研究不同过盈量对装配的影响,预先掌握装配过程中的薄弱环节,提高产品装配质量,基于此,本文应用有限元技术计算分析提出了较为合理的结构形式。
基于485通信的压缩机注油检测系统设计

为了确保生产线上的所有压缩机都能够得到加工,设计了一个基于485串行通信的多台压缩机注油检测系统。系统由上位机和下位机组成,能够实现同一流水线上四台PLC同时运行并将数据上传,而且能够应用于多条流水线。下位机包括PLC与触摸屏。下位机通过获取PLC内的注油数据从而获取向压缩机注入的油量,检测注油加工过程是否合格。上位机经由RS232转RS485端口完成485串行通讯与多台PLC连接,读取产品信息和加工状态。它依据三菱通信协议(其中包括MC协议),使用VB6.0开发了上位机与PLC之间通信的程序,并实现注油量的检测与数据传输,将海量数据存入SQL server数据库。该检测系统已在实际生产中得到了成功应用。系统自动检测对比,确保加工质量,避免了工人的重复劳作,提高了生产效率。
衍射光栅机械刻划成槽过程中的应力拓扑分析

衍射光栅机械刻划属于超精密刻划,其刻划过程是利用金刚石刻刀对铝膜材料进行的多线顺序刻划。由于光栅槽面精度要求较高,而光栅槽面精度与其表面应力分布有很大关系,为此我们以衍射光栅为研究背景,通过CATIA对金刚石尖劈刀进行三维建模并利用缩小比例功能在DERORM-3D中建立衍射光栅机械刻划的有限元仿真模型,以更好地分析衍射光栅机械刻划过程中光栅槽面的应力分布情况,揭示衍射光栅机械刻划过程中槽面的弹塑性变形规律,为提高槽形质量提高依据。
外泌体在器官移植中作用的研究与展望

外泌体(exosomes)不是一个新的概念,30年前发现它的时候,认为它只不过是红细胞在发育过程中的生理性“废弃物”的囊状结构体。近期越来越多的研究结果提示,外泌体可以存在于各种体液中,通过从特定的细胞运送功能分子到另一个受体细胞,实现细胞间的远程交流,并协助完成很多重要的生理性和病理性的生理进程,例如蛋白分泌、抗原提呈、病原体转移和肿瘤演进等。本文对外泌体的新近研究进展进行概述,旨在与广大同行共同关注、思考和探索外泌体在器官移植领域的研究意义和价值。
Particle swarm optimization and its application to seismic inversion of igneous rocks

In order to improve the fine structure inversion ability of igneous rocks for the exploration of underlying strata, based on particle swarm optimization (PSO), we have developed a method for seismic wave impedance inversion. Through numerical simulation, we tested the effects of different algorithm parameters and different model parameterization methods on PSO wave impedance inversion, and analyzed the characteristics of PSO method. Under the conclusions drawn from numerical simulation, we propose the scheme of combining a cross-moving strategy based on a divided block model and high-frequency filtering technology for PSO inversion. By analyzing the inversion results of a wedge model of a pitchout coal seam and a coal coking model with igneous rock intrusion, we discuss the vertical and horizontal resolution, stability and reliability of PSO inversion. Based on the actual seismic and logging data from an igneous area, by taking a seismic profile through wells as an example, we discuss the characteristics of three inversion methods, including model-based wave impedance inversion, multi-attribute seismic inversion based on probabilistic neural network (PNN) and wave impedance inversion based on PSO. And we draw the conclusion that the inversion based on PSO method has a better result for this igneous area.
Stability of roof structure and its control in steeply inclined coal seams

To improve the effectiveness of control of surrounding rock and the stability of supports on longwall topcoal caving faces in steeply inclined coal seams, the stability of the roof structure and hydraulic supports was studied with physical simulation and theoretical analysis. The results show that roof strata in the vicinity of the tail gate subside extensively with small cutting height, while roof subsidence near the main gate is relatively assuasive. With increase of the mining space, the caving angle of the roof strata above the main gate increases. The characteristics of the vertical and horizontal displacement of the roof strata demonstrate that caved blocks rotate around the lower hinged point of the roof structure, which may lead to sliding instability. Large dip angle of the coal seam makes sliding instability of the roof structure easier. A three-hinged arch can be easily formed above both the tail and main gates in steeply inclined coal seams. With the growth in the dip angle, subsidence of the arch foot formed above the main gate decreases significantly, which reduces the probability of the roof structure becoming unstable as a result of large deformation, while the potential of the roof structure’s sliding instability above the tail gate increases dramatically.
Evaluation of line brattice length in an empty heading to improve air flow rate at the face using CFD

The effectiveness of line brattice (LB) ventilation system depends on the associated system variables. However, the effect of these variables on the air flow rates close to the face of the heading is not extensively studied. In this paper, the effect of the LB length in relation to the LB-wall distance on the air flow rate reaching the face is analysed. Scenarios were developed using four LB lengths, two LB-wall distances and two heading depths. These scenarios were simulated with a validated CFD model. The air flow rates and patterns at various locations inside the heading were analysed. This helped to find the minimum LB-face distance that should be maintained for each LB-wall distance to maximise the air flow rate at the face. The minimum length when used will improve ventilation and reduce energy cost.