Research on controlling long-term performance by tensioning post tendon of long-span continuous rigid-frame bridges

The problems like cracking of the girder in the mid-span and the ever-increasing vertical deflection appear during the long term usage of the long-span continuous rigid-flame bridge. Post-tension tendon with re- served duct can increase the pre-stress of the main beam effectively, and decrease the long term span deflection in order to improve the performance of the girder. At the same time, the proper tension position is very crucial to optimise the stress distribution of the bridge and control the deflection increase. Combining with practical en- gineering, the authors analyze the influence of different positions of post-tension tendon （ including top-, web- and bottom plate tendons） on the stress and deflection of the main beam, and find out the optimal position of post tendon.

Assessment of Durability and Long Term Performance of High Density Polyethylene Drainboards in the Gotthard Railway Tunnels

Drainage layers provide permanent relief of hydrostatic water pressure, while the waterproof liner prevents any ingress of water into the tunnel. The durability and aging resistance of drainage membranes are of primary concern. This paper describes advantages and concerns related to the usage of, and the design with, polymeric drainboards in tunnel construction. Common degradation mechanisms associated with HDPE （high density polyethylene） sheets are described. The stringent requirements for the Gotthard Alpine Railway Tunnel through the Swiss Alps, e.g., high ambient temperatures of up to 45 ℃ and an expected service life of up to 100 years require outstanding aging resistance of polymeric drainage materials. The paper describes the methods deployed to investigate the long-term performance of HDPE drainboards, focusing on aging mechanisms. Details associated with the test procedures developed to reflect the specific properties of drainboards, as well as the results obtained, are presented. A summary table shows recommended product specifications needed to confine the aging properties of drainboards and to design a system performing adequately during the entire lifetime of the structure.

Long-term Performance of Moderate Heat Portland Cement with Double-expansive Sources

The long-term performance of moderate heat Portland cement with double-expansive sources （DE cement） in the system of high MgO clinker and gypsum was studied by XRD, SEM/EDAX and test methods for strength and expansion of cement. Results indicate that the periclase particle, whose size was 5-7.5μm in DE cement clinker containing 4.8 % MgO, existed individually. The periclase hydration in hardened DE cement paste started at about 60 days and completed up to 2 000 days, and ettringite in the paste was stable from 3 days to 2 000 days. Under the conditions of 4.5%-5.0 % MgO in clinker and 2.8%-3.4 %SO3 in cement, ettringite expansion and brucite expansion in DE cement paste had a continuity, entirety and stability. At the ages of 90, 365,730 and 2 000 days the expansion of the paste reached 0.07%-0.11%, 0.16%-0.21%, 0.21%-0.27 %, and 0.29%-0.38%, respectively. The results suggest that by using this cement in mass concrete it may compensate its temperature shrinkage and autogenous shrinkage to some extent.

KOH-assisted aqueous synthesis of ZIF-67 with high-yield and its derived cobalt selenide/carbon composites for high-performance Li-ion batteries

To solve the environmental pollution and low yield during the sythesis of zeolitic imidazolate frameworks(ZIFs)and their derived materials,a KOH-assisted aqueous strategy is proposed to synthesize cobalt zeolitic imidazolate framework(ZIF-67)polyhedrons,which are used as precursors to prepare cobalt selenide/carbon composites with different crystal phases(Co_(0.85)Se,CoSe_2).When evaluated as anode material for lithium ion batteries,Co_(0.85)Se/C composites deliver a reversible capacity of 758.7 m A·h·g^(-1)with a capacity retention rate of 90.5%at 1.0 A·g^(-1)after 500 cycles,and the superior rate capability is 620 m A·h·g^(-1)at 2.0 A·g^(-1).The addition of KOH accelerates the production of ZIF-67 crystals by boosting deprotonation of dimethylimidazole,resulting in rapid growth and structures transition from two-dimensional to three-dimensional of ZIF-67 in aqueous solution,which greatly promotes the application of MOFs in the field of energy storage and conversion.

3D skeleton nanostructured Ni_3S_2/Ni foam@RGO composite anode for high-performance dual-ion battery

The growing global demands of safe, low-cost and high working voltage energy storage devices trigger strong interests in novel battery concepts beyond state-of-art lithium-ion battery. Herein, a dualion battery based on nanostructured Ni_3S_2/Ni foam@RGO(NSNR) composite anode is developed, utilizing graphite as cathode material and LiPF6-VC-based solvent as electrolyte. The battery operates at high working voltage of 4.2–4.5 V, with superior discharge capacity of ～90 m A h g^(-1) at 100 mA g^(-1), outstanding rate performance, and long-term cycling stability over 500 cycles with discharge capacity retention of ～85.6%. Moreover, the composite simultaneously acts as the anode material and the current collector, and the corrosion phenomenon can be greatly reduced compared to metallic Al anode. Thus, this work represents a significant step forward for practical safe, low-cost and high working voltage dual-ion batteries,showing attractive potential for future energy storage application.

Long Term Assessment of a Grid Connected Solar PV System in Sydney

This paper assesses 4 years of operation of a 1.75 kW roof top solar PV system installed in a Sydney suburban house. The system consists of 10 PV panels, a DC/AC inverter, and a grid connected gross meter. Solar electricity delivered to grid is verified with the results from a computer simulation package （PVSYST） by adopting the installed component specifications, operation conditions, and weather data of the site. The results show high consistency between the values of energy delivered to the grid measured by the energy company and the energy estimated by system simulation. New system performance indicator is developed and called the optimum performance compliance ratio （PCR）. It is a measure of the compliance of the output of the designed PV system with the output which would be produced by the same system with a solar tracker. This indicator provides system designers, contractors and energy providers with the actual capacity of the system that they can offer the end-users.

TCP TRAFFIC PERFORMANCE IMPROVING IN LTE-A NETWORKS

This paper presents a novel way to improve Transmission Control Protocol (TCP) performance of the users at the edge areas of the macro cells in Long Term Evolution Advanced (LTE-A) systems. Previous works on improving wireless TCP performance are reviewed and current considerations on TCP in LTE-A are explained. However, those solutions are neither too complex nor limited to some presuppositions which are too restricting for the deployment of LTE-A networks. In this paper a substituted TCP acknowledgement transmission scheme based on Automatic Repeat reQuest (ARQ) information in layer 2 is proposed. The simulation result shows that the proposed method can reduce the delay and improve the throughput of the edging users of the cell, as well as reducing radio resources in LTE-A macro cells.

Mechanisms by which fibroblast growth factor 20 improves motor performance in a mouse model of Parkinson’s disease

Genome-wide studies have reported that Parkinson’s disease is associated with abnormal expression of various growth factors. In this study, male C57 BL/6 mice aged 10 weeks were used to establish Parkinson’s disease models using an intraperitoneal injection of 60 mg/kg 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. 28 days later, 10 or 100 ng fibroblast growth factor 20 was injected intracerebroventricularly. The electrophysiological changes in the mouse hippocampus were recorded using a full-cell patch clamp. Expression of Kv4.2 in the substantia nigra was analyzed using a western blot assay. Serum malondialdehyde levels were analyzed by enzyme-linked immunosorbent assay. The motor coordination of mice was evaluated using the rotarod test. The results showed that fibroblast growth factor 20 decreased A-type potassium current in neurons of the substantia nigra, increased long-term potentiation amplitude in the hippocampus, and downregulated Kv4.2 expression. A high dose of fibroblast growth factor 20 reduced serum malondialdehyde levels and enhanced the motor coordination of mice. These findings confirm that fibroblast growth factor 20 has a therapeutic effect on the toxicity induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and its mechanism of action is associated with the inhibition of A-type K+ currents and Kv4.2 expression. All animal procedures were approved by the Animal Care and Use Committee of Qilu Hospital of Shandong University, China in 2017(approval No. KYLL-2017-0012).

Long-term survival of more than 3 years among patients with advanced non-small cell lung cancer treated with chemotherapy

AIM: To evaluate the prognostic factors of long-term survival of more than 3 years in patients with advanced non-small cell lung cancer(NSCLC). METHODS: We retrospectively analyzed the records of 474 patients with advanced ⅢB/Ⅳ NSCLC who received chemotherapy as initial treatment between September 2002 and March 2007.RESULTS: The median survival time(MST) was 12.5 mo and the 3 year and 5 year survival rates were 14.6% and 5.3%, respectively. Long-term survival of more than 3 and 5 years was observed in 65 and 16 patients, respectively. The MST for the 65 patients was61.5 mo(range, 60.1-81.0 mo). In the 474 patients, a good performance status(PS), female sex, non-smoking status and adenocarcinoma histology were significantly associated with a favorable outcome. Furthermore, female sex, a good PS, non-smoking status and adenocarcinoma histology were significantly correlated with longterm survival of more than 3 years and most of these patients(89.2%, 58/65) received epidermal growth factor receptor-tyrosine kinase inhibitors as any line treatment. Survival analysis of long-term survivors showed that a PS of 0 was an independent prognostic factor for predicting favorable outcomes. CONCLUSION: Our results suggest that a good PS and adenocarcinoma histology play an important role in long-term survival of more than 3 years. A PS of 0 was an independent prognostic factor for predicting favorable outcomes in patients with advanced NSCLC who survived for more than 3 years.

Nonlinear Differential Equation of Macroeconomic Dynamics for Long-Term Forecasting of Economic Development

In this article we derive a general differential equation that describes long-term economic growth in terms of cyclical and trend components. Equation is based on the model of non-linear accelerator of induced investment. A scheme is proposed for obtaining approximate solutions of nonlinear differential equation by splitting solution into the rapidly oscillating business cycles and slowly varying trend using Krylov-Bogoliubov-Mitropolsky averaging. Simplest modes of the economic system are described. Characteristics of the bifurcation point are found and bifurcation phenomenon is interpreted as loss of stability making the economic system available to structural change and accepting innovations. System being in a nonequilibrium state has a dynamics with self-sustained undamped oscillations. The model is verified with economic development of the US during the fifth Kondratieff cycle (1982-2010). Model adequately describes real process of economic growth in both quantitative and qualitative aspects. It is one of major results that the model gives a rough estimation of critical points of system stability loss and falling into a crisis recession. The model is used to forecast the macroeconomic dynamics of the US during the sixth Kondratieff cycle (2018-2050). For this forecast we use fixed production capital functional dependence on a long-term Kondratieff cycle and medium-term Juglar and Kuznets cycles. More accurate estimations of the time of crisis and recession are based on the model of accelerating log-periodic oscillations. The explosive growth of the prices of highly liquid commodities such as gold and oil is taken as real predictors of the global financial crisis. The second wave of crisis is expected to come in June 2011.

基于岩石CT扫描的冻融作用对花岗岩细观结构及力学强度影响研究

近年来随着西部地区的基础工程建设数量及规模不断增加,西部高原地区的季节性冻融循环效应的影响也随之增强,开展冻融循环作用下岩石细观特性及强度劣化性质研究对指导西部寒区基础工程建设至关重要。首先在偏光显微镜下对岩石薄片进行观察,获取岩石的矿物成分和微结构;接着利用CT扫描技术,对冻融后的花岗岩进行扫描,对扫描图层利用阈值分割进行二值化处理,堆叠得到样品内外结构的高分辨3D数据及影像;结合分形理论计算图像计盒维数并由此对图像复杂度做出量化判断,由此对冻融循环对花岗岩内部结构演化分布特点进行分析;进而揭示其强度演化规律,探究结构演化与强度之间的关系。偏光显微镜下,岩石呈块状构造,具有似斑状粗粒不等粒花岗结构,局部见交代蠕虫结构。似斑晶矿物主要为碱性长石;其他矿物粒径0.25~4.0 mm为主,矿物成分主要为石英、斜长石、碱性长石,次要矿物为黑云母、绿帘石,副矿物有磷灰石、锆石、黄铁矿等,镜下鉴定为似斑状粗粒不等粒黑云二长花岗岩。CT扫描显示,冻融循环效应在影响花岗岩细观结构时,会导致花岗岩内部孔隙率的整体上升,但岩石渗透性变化不大,岩石渗透率仅上升0.003×10^(-3)μm^(2);内部孔隙发育不均匀,试样整体结构改变以萌生较多新的微孔隙为主。冻融循环后岩石内部结构复杂度有所下降,但岩石整体完整性仍然较好,分形维数仍保持在较高水平。分形研究显示,20次冻融循环并未导致花岗岩的结构复杂度发生较大变化,同时试样整体力学特性出现下降,黏性增加以及长期强度出现较大幅度的衰减,进入蠕变试验阶段的应变阈值提高。在评价此类原生结构较致密的岩石的安全性时,仅从结构上进行考量与实际情况往往会出现偏差,应结合必要的强度指标综合评估。岩石在经历冻融循环后,在强度更低的同时会发生更大的变形。该研究可为分形理论在岩石细观结构演化方面的应用及岩石细观结构与强度演化相关研究提供借鉴,并对高寒地区工程施工有指导意义。

酸性花岗岩沥青混合料水稳性试验

为提高高湿热地区花岗岩沥青混合料的长期水稳性能,分别进行单掺3%水泥、4%水泥及30%消石灰水浸泡处治,通过冻融、冻融烘循环的劈裂试验来评价酸性花岗岩沥青混合料的长期适用性与水稳性能,并与未处治酸性花岗岩沥青混合料进行对比分析。结果表明:随着冻融、冻融烘次数的增加,处治后酸性花岗岩沥青混合料在3种试验条件下的劈裂强度与残留强度比呈整体下降趋势;冻融循环条件下,4%水泥>3%水泥>30%消石灰水>未处治集料;冻融烘循环条件下,4%水泥>3%水泥>30%消石灰水>未处治集料。

基于企业绩效视角的知识产权文本信息披露有效性研究

本文基于《知识产权相关信息披露规定》颁布这一外生冲击构建连续型DID模型,基于企业绩效视角考察知识产权文本信息披露的有效性。结果表明:在信息披露的信息效应和内损效应的影响下,《规定》颁布后企业披露的知识产权文本信息对企业绩效存在异质性影响。知识产权信息披露短期内并未给企业带来盈利能力的提升,而从长期看知识产权信息披露反映了市场对公司的良好预期。债权融资水平的降低是知识产权信息披露降低企业短期绩效的潜在机制,权益资本成本的降低是知识产权信息披露提升企业长期绩效的潜在机制。按信息类型分类分析发现,优势信息和内容信息与短期绩效的负向关系更显著,内容信息、优势信息和风险信息对长期绩效的正向影响程度依次减弱。截面分组发现,成长期和衰退期企业知识产权信息披露与短期绩效的负向关系更显著,成长期和成熟期企业知识产权信息披露与长期绩效的正向关系更显著。研究不仅证明了知识产权信息披露对企业绩效存在的差异性影响,也对政府逐步完善知识产权信息披露政策,企业更好地开展知识产权信息披露的实践活动均具有借鉴意义。

考虑土-膨润土化学相容性的阻隔墙长期服役性能研究

考虑到填埋场渗滤液中较高Na^(+)和Ca^(2+)浓度会让土-膨润土的渗透系数显著增大,从而加速高危害性污染物击穿土-膨润土阻隔墙,建立了Na^(+)和Ca^(2+)作用下土-膨润土阻隔墙-含水层系统中有机物污染物运移数值模型。该模型可以考虑渗透系数和水动力弥散系数等参数随Na^(+)和Ca^(2+)浓度的变化。利用有限差分法,获得了该模型的数值解。通过将所建模型的计算结果分别与已有解析解计算结果和COMSOL软件计算结果进行对比分析,验证了模型的正确性。最后基于所建数值模型,以甲苯作为代表性有机污染物分析和讨论了考虑和未考虑土-膨润土化学相容性、水头差和膨润土掺量对阻隔墙长期服役性能的影响。结果表明:考虑土-膨润土化学相容性之后,阻隔墙从不会被击穿变成了服役75 a后被击穿,服役寿命大幅缩短;降低阻隔墙两侧水头差,能够有效延缓污染物的击穿时间;阻隔墙膨润土掺量的下限值应在原先防渗要求的基础上适当提高,以应对污染物作用下墙体防污阻隔性能的削弱。

融入课程知识图谱的KMAKT预测

现有多数深度知识追踪模型的知识追踪结果的可解释性弱,且忽视了习题与知识点的内在关联性对知识追踪效果与预测结果的影响。针对上述问题,提出一种用于学生表现预测的结合课程知识图谱与多头注意力机制的知识追踪(KMAKT)模型。首先,采用Word2Vec和双向长短期记忆(Bi LSTM)网络将习题作答序列数据转换为低维稠密向量,利用图嵌入模型Trans R进行课程知识图谱嵌入表示,并使用多头注意力机制计算过往习题作答序列对当前知识状态的贡献程度;然后,通过注意力网络挖掘前驱知识对预测结果的影响程度;最后,通过多层神经网络获取预测结果,提高模型的可解释性与预测精度。实验结果表明,KMAKT模型在ASSISTments2017数据集上的受试者工作特征曲线下的面积(AUC)、准确率和F1值相比于深度知识追踪(DKT)模型分别提升了约5.20、4.20和2.40个百分点,具有较好的预测性能。在湖南大学信号与系统(HNU_SYS)子数据集上的知识追踪可视化结果验证了KMAKT模型的知识追踪结果符合教育学认知规律且具备一定程度的可解释性。

自我革命:跳出治乱兴衰历史周期率的第二个答案

中国共产党在百余年奋斗历程中始终保持高度的居安思危意识,从未停止对跳出历史周期率的探索和思考,并以实际行动回应这一重大考题。在毛泽东同志给出“人民监督”民主新路跳出历史周期率的第一个答案的基础上,习近平总书记给出“自我革命”从严治党跳出历史周期率的第二个答案。自我革命彰显了党始终坚守人民立场的价值取向与历史自觉,构成中国共产党区别于其他政党的显著标志,成为管党治党兴党强党的集中体现。自我革命与人民监督同心同源、情理相依,内呼外应、水乳交融,共同归向人民幸福与民族复兴,一道构成长治久安的动力源泉,协同彰显党鲜明的历史主动精神与创造精神。新时代党的自我革命应在坚持党性与人民性的统一、集中领导与党内民主的统一、思想武装与制度保障的统一、问题导向与全面深化的统一中进行到底,确保党跳出历史周期率实现长期执政,始终成为中国特色社会主义事业的坚强领导核心,永远做中国人民和中华民族的主心骨。

中华优秀传统文化核心思想理念视角下预算绩效管理的优化研究

预算绩效管理是财政管理中的重要环节,也是当前我国财政管理改革的主要着力点。它对于完善财政管理体制和财政资金管理具有重要作用。但预算绩效管理制度舶来品的属性明显,本土化任务繁重。本文详尽分析中华优秀传统文化核心思想理念,发掘其蕴含的预算绩效管理价值,应用中华优秀传统文化核心思想理念重新诠释预算绩效管理,寻求优化路径。本文建议以“讲仁爱、重民本”为前提与出发点,推演人民至上观;以“守诚信、崇正义”为过程与手段,追求道德约束观;以“尚和合、求大同”为目标与方向,提炼长远全局观,从而实现预算绩效管理与中华优秀传统文化的融合发展,促进预算绩效管理有效实施。

麻雀搜索算法优化的外啮合齿轮泵泄漏量预测

预测齿轮泵泄漏量的变化趋势有助于定量分析其性能退化过程。变分模态分解(Variational Modal Decomposition, VMD)方法对齿轮泵原始泄漏量数据进行变分模态分解,得到本征模态函数IMF,提出一种结合麻雀优化算法(Sparrow Search Algorithm, SSA)和长短期记忆神经网络(Long-Short Term Memory, LSTM)的模型,建立VMD-SSA-LSTM模型预测齿轮泵泄漏量的变化情况,并对每一个分量进行单独预测,最后将预测结果进行叠加,获得完整的预测结果。通过对比不同时间段预测结果可知,VMD-SSA-LSTM模型较单一的LSTM模型预测结果的平均相对误差最高可减小25.2%,能够完成对泄漏量的有效预测。研究结论可为齿轮泵性能衰退的定量预测提供理论支持。

董监高履职风险缓释与企业“专精特新”转型——基于董监高责任险的经验证据

党的二十大明确将培育“专精特新”企业作为建设现代化产业体系的重要内容。然而,企业“专精特新”转型存在极大的不确定性,如何增加激励驱动转型成为培育“专精特新”企业的重要考量。本文从董监高履职风险缓释的视角探究了董监高责任险对企业“专精特新”转型的影响。研究发现,企业购买董监高责任险后的风险缓释能够促进企业“专精特新”转型。异质性分析表明,这一效应在小规模企业和高竞争性行业中更显著。本文有助于加深对我国董监高责任险制度运行成效的认识,并可从企业内部治理的角度为培育“专精特新”企业提供相关建议。

Experimental Study on Long Cycling Performance of NCM523 Lithium-Ion Batteries and Optimization of Charge-Discharge Strategy

With the increasing demand for clean renewable energy and electric cars,people have put forward higher requirement for the energy storage system.One of the most successful lithium-ion batteries with a cathode combination of lithium nickel manganese cobalt oxide(also called NCM lithium-ion battery),has been playing an increasingly important role.So far,numerous research has been done on the fabrication of cathode material with optimization of its composition,design,and assembly of the battery system in order to improve the energy storage performance.However,most of the previous studies were conducted based on relatively short cycling time of testing,with limited charge-discharge cycles of no more than 1000.Thus the conclusions were insufficient to be applied in the practical working condition.In this work,by using the developed NCM523 lithium-ion batteries,we have performed a series of ultra-long cycling tests on the individual cell and its module,with a comprehensive study on the relationship between the retained capacity after long cycling time and the depth of discharge(DOD),charge-discharge rate and operating temperature.Optimization of the charge-discharge strategies on a single cell and the whole module was also made to effectively improve the overall energy storage efficiency.This experimental study offers a guideline for the efficient use of similar types of lithium-ion batteries in the practical working condition.The developed batteries together with the optimized charge-discharge strategy proposed here are promising to meet the requirements for applications of stationary energy storage and electric cars.