Longitudinal force in continuously welded rail on long-span tied arch continuous bridge carrying multiple tracks

Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube(CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a(77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail(CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load.Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.

Optimum Design of Tied Back Retaining Wall

This paper presents an optimization algorithm for the design of tied back retaining wall which is comprised of the same three basic elements: stem, toe and heel, where the stem is hinged to the base and tied to the heel by multiple tie rods at intervals along the wall. The aim of this study is to find the values of design variables for this suggested type of tied back retaining walls which minimize the cost function subjected to constraints of the problem. The optimum design of such structure is conducted by using one of the nontraditional optimization methods, genetic algorithm (GA). The formulation of the problem is based on the elastic analysis and the ultimate strength method of design as per ACI-318-2011 code. The built-in genetic algorithm optimtool of Matlab program is utilized to optimize the cost function of the wall. The cost of concrete, reinforcing steel, tie steel, formwork, excavation, and backfilling works are included. The considered design variables are the geometric dimensions and the amounts of reinforcement for the base slab and stem slab, as well as the amount of tie steel. The developed program is utilized to perform an extensive parametric study regarding the height of wall, backfill soil properties, and materials properties including concrete, reinforcing steel, and tie steel. The backfill properties are represented by a pressure coefficient, which is a function of the unit weight and the angle of internal friction. Average expressions are calculated for the total cost and optimum dimensions as ratios of the wall height H2 which may be useful for the practical design of walls.

Effect of Maize/Haricot Bean Intercropping on Soil Fertility Improvement under Different Tied Ridges and Planting Methods, Southeast Ethiopia

Mono cropping is the dominant factor influencing plant nutrient uptake and loss of soil quality in Ethiopia whereas intercropping of cereal/legume has positive environmental qualities. Likewise drought and moisture stress condition is widely expanding from all direction to the center of the country. Therefore, the objective of this research was to evaluate influence of planting methods, tied ridge and cropping system on different soil chemical properties in case of Madda Walabu district, Southeast Ethiopia. It was undertaken at Bidire from March 2016 to January, 2017. In this experiment, one maize variety (Melkassa 2) and one haricot bean variety (Nasir) were used. Treatments include open end and closed end tied ridge;sole cropping and intercropping;and in furrow, on ridge and flat bed planting. Each treatment has been triplicate and the experiment plots were laid out in randomized complete block design. Intercropping of maize-haricot bean with tied ridge and planting methods were highly influenced soil pH, exchangeable potassium, available phosphorous, soil organic matter and total soil nitrogen. Generally, the use of intercropping and closed end tied ridge in combination with in furrow planting significantly increased (p0.05) soil fertility in the system, which could be promising for sustainable improvement of crop production and productivity for semi arid areas of Bale zone.

Increasing the Efficiency of Grid Tied Micro Wind Turbines in Low Wind Speed Regimes

Major problem with grid tied micro wind turbine is synchronization and wind variability. Due to this problem the stability of available grid gets reduced. The stability can be achieved by output power control of the turbine. Major part of many countries like India, the annual mean wind speed is not high. The rated wind speed of turbine remain around 11 m/s and cut in is around 3.5 m/s. Due to this problem we aimed to develop a sustainable wind energy system that can provide stable power supply even at the locations of low wind speed of 2 - 4 m/s. To address this issue, a momentary impulse or external torque to the rotor by external motor is one of the good options to maintain the momentum of blades and thus provide stability for sufficient time. Various theoretical calculations and experiments are conducted on the above method. This would increase the output power and also the efficiency of wind turbine. We show that Return-On-Investment will be high as compared with other grid connected turbines. Our proposed concept in the present study, if implemented properly, can help the installation of number of wind turbines even at domestic level. It also makes the consumers energy independent and promotes the use of wind as a source of energy and may enter as a rooftop energy supply system similar to solar.

Innovative Design and Development of Simplysupported Tied Arch of Beijing-Shanghai HSR

Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply-supported tied arch is systematically studied and widely applied for the first time.A total of 21 simplysupported tied arch bridges with the spans of 96 m,112 m and 128 m respectively are constructed for the route.The simply-supported tied arch is an external static and internal super-static parallel arch or basket arch of Nielsen system in structure;single-box,threechamber and equal-height prestressed concrete box girder is adopted for the tie beam;dumbbell steel pipe concrete section is adopted for the arch rib;PES(FD)low-stress anticorrosion cable body is adopted for the suspender.The rational structural form is determined by comparative study on the key technical parameters such as the layout form of suspender,rise-span ratio and arch axis alignment.This paper summarizes the optimization of simplysupported tied arch structure and looks forward to the development of bridge structure.

Tie Someone Down/Tied Down

“The holidays are over,”Mother smiled.“New classesstart tomorrow,so get to bed early.From now on your studiesare going to tie you down.”Penelope groaned.“Gee,we’re

Analysis on Construction Technology of Reinforced Concrete Tied Arch Bridge

Bridge construction has received a lot of attention as transportation continues to improve.Reinforced concrete linked arch bridges are a common bridge style in today’s bridge construction.This type of bridge not only has a basic and generous shape,but it is also incredibly easy to construct,resulting in significant material and construction cost savings.This article analyzes the construction technology of a reinforced concrete linked arch bridge in order to achieve good construction and application.It is hoped that this analysis can provide a scientific reference for the guarantee of the construction quality and subsequent application effect of this kind of bridge.

Analysis of Key Technologies in the Design of Small and Medium Span Basket Type Steel Box Tied Arch Bridge

In order to ensure the construction quality and safety of small and medium span basket type steel box tied arch bridge,this paper takes a practical project as an example to analyze the key technologies in its design process.It is hoped that this analysis can provide corresponding reference for the design and construction of this kind of arch bridge.

Evaluation of series-parallel-cross-tied PV array configuration performance with maximum power point tracking techniques under partial shading conditions

Tracking the maximum power point is a critical issue with solar systems.The power output of the solar panel varies due to variations in irradiance and temperature.Nonuniform irradiation due to partial shading conditions has a direct impact on the characteristics of photovoltaic(PV)systems.To build a diversity of maximum power point tracking algorithms in solar PV systems,this work focuses on perturb and observe,incremental conductance,and fuzzy logic control methodologies.The suggested fuzzy logic control method outperformed the conventional incremental conductance and perturb and observe algorithms with a collection of 49 rules.This paper presents a novel series-parallel-cross-tied PV array configuration with a developed fuzzy methodology.To comment on the performance of a proposed system under various partial shading conditions,a series-parallel PV array configuration has been considered.The simulation result demonstrates that the fuzzy method has a percentage improvement in the global maximum power point tracking efficiency of 24.85%when compared to the perturb and observe method and a 65.5%improvement when compared to the incremental conductance method under long wide partial shading conditions.In the case of the middle partial shading condition,the fuzzy method has a percentage improvement in the global maximum power point tracking efficiency of 12.4%compared to the perturb and observe method and a 60.7%improvement compared to the incremental conductance method.

脓毒症诊治中Ang/Tie信号通路的研究进展

脓毒症以及伴随的多器官功能障碍是一组常见的临床综合征,其患病率随着人口老龄化逐年上升。全球每年发生2000万例脓毒症,死亡率为26%。早期准确诊断脓毒症,有利于及时采取针对性的治疗策略,这是降低病死率的关键。内皮细胞是外源病原体或内源性损伤信号的早期作用对象。研究提示,内皮细胞的结构改变与功能活化在脓毒症的发生、发展中发挥重要作用。作为内皮细胞专属信号通路,血管生成素(angiopoietin,Ang)/酪氨酸激酶受体(tyrosine kinase receptor,Tie)在内皮细胞的异常激活和损伤中发挥重要作用。Ang/Tie信号通路主要包括2种位于内皮细胞中的酪氨酸激酶受体(Tie1、Tie2)和4种分泌性糖蛋白配体(Ang-1、Ang-2、Ang-3、Ang-4)。机制研究方面,Ang-1可持续性激活Tie2受体,维持细胞与细胞、细胞与基质间的相互作用,支持血管内皮细胞正常的生理功能;Ang-2是Ang-1拮抗剂,可竞争性阻断Ang-1与Tie2受体结合。脓毒症环境下,Ang-1下降,Ang-2升高,Ang-1/Ang-2的比值下降。Ang-2竞争性阻断Ang-1与可溶性Tie2受体结合,内皮细胞处于严重异常激活状态。Ang-2介导肝素酶的释放导致糖萼损伤,可引起血管通透性增加;Ang-2可促进炎症反应;Ang/Tie信号系统失调介导凝血功能障碍,Ang-2升高是弥散性血管内凝血的前哨性事件。临床病情监测方面,Ang-2>5.61 ng/mL,诊断脓毒症的灵敏度为74.36%;Ang-2持续升高,提示内皮功能难以恢复,器官发生功能性改变。早期动态监测Ang-2可用于预测脓毒症相关肺损伤、急性肾损伤。Ang-2/Ang-1比值上升、Ang1/可溶性Tie2比值下降可预测脓毒症患者90 d病死率(ROC曲线面积分别为0.787和0.704)。Ang-2和可溶性Tie-2水平下降,则提示脓毒症血浆置换有效。靶向Ang/Tie信号通路的动物实验获得一定成功,但目前临床试验未能获得有价值的结果。脓毒症相关Ang/Tie信号通路有待于进一步深入研究。

调控Ang/Tie信号通路治疗眼底新生血管性疾病的研究进展

抗血管内皮生长因子(VEGF)治疗应用于眼底新生血管疾病领域以来,在提高视力、稳定疾病病变和在某些情况下逆转疾病方面显示了卓越的效果。但抗VEGF治疗需要频繁玻璃体内注射给药,患者治疗负担重,长期疗效受影响。前期临床研究发现,调控血管生成素(Ang)/含免疫球蛋白样环和上皮生长因子样域酪氨酸激酶(Tie)通路在眼底新生血管疾病的治疗中有较好的效果。目前已发布了3个Ang/Tie通路阻断药物治疗眼底新生血管疾病的临床研究数据,其中靶向VEGF-A和Ang-2的双特异性免疫球蛋白G1抗体faricimab进入了Ⅲ期临床试验并达到终点,faricimab的2种延长治疗间隔(12周和16周)的给药方案均被证实有效。本文基于已发表的研究报告,就调控Ang/Tie通路在眼底新生血管性疾病治疗中的作用及临床应用作一综述,总结分析Ang/Tie通路的作用机制以及未来药物的应用前景。

Changes of China’s Status in the Global System and Its Influencing Factors:A Multiple Contact Networks Perspective

Clarifying China’s position in the global system is an important logical basis for developing national diplomacy.Although much research has been done on China’s development status,most studies have been based on country comparisons or institutional en-vironment.In today’s networked era in which the global economy,trade,personnel,and information are closely connected,studies on China’s global position and its status changes and influencing factors in multiple contact networks are still insufficient.In this study,from the perspective of diverse global contact networks,we constructed economic,cultural,and political influence indices to explore the changes and influencing factors on China’s status in the global system from 2005 to 2018.The results show that during the study period,China’s global influence in the fields of economic ties,cultural exchanges,and political contacts increased significantly,but its influ-ence in the fields of cultural exchanges and political contacts lagged far economic ties.The pattern of China’s economic influence on various economies around the world has shown a transformation from an‘upright pyramid’to an‘inverted pyramid’structure.The proportion of these economies in low-influence zones has decreased from more than 60%in 2005 to less than 20%in 2018.China’s cultural and political influence on various economies around the world has increased significantly;however,for the former,the percentage of high-influence areas is still less than 20%,whereas for the latter the percentage of these economies in medium-and high-influence areas is still less than 50%.Analyses such as a scatter plot matrix show that geographical proximity,economic globalization,close cooperation with developing countries,and a proactive and peaceful foreign policy are important factors in improving China’s status in the diverse global network system.

骨形态发生蛋白4诱导下骨骼肌内异位骨化的细胞来源

背景:骨骼肌异位骨化是临床上严重的并发症。对于骨骼肌异位骨化而言,其参与成骨过程中的细胞仍不明确。目的:观察肌细胞及筋膜细胞以及内皮细胞在骨肌中异位骨化过程中的参与情况,观察骨形态发生蛋白4诱导下骨骼肌内异位骨化的细胞来源。方法:培养C2C12细胞和诱导培养基数天下C 2 C 12细胞形成的肌管,将质量浓度500 ng/mL骨形态发生蛋白4分别加入培养基后,显微镜下观察处理10 d内C2C12细胞和肌管是否继续增殖;按不同比例共培养大鼠肌细胞(L6)和人成纤维源性细胞(fibroblast-derived cells,FDC),通过番红O染色和阿尔新蓝染色研究上述细胞在质量浓度500 ng/mL的骨形态发生蛋白4和质量浓度10 ng/mL的转化生长因子β3处理下21 d内成骨和成软骨分化潜力。使用转基因动物FVB/N-TgN(TIE2-LacZ)182Sato小鼠,通过在基因鼠大腿肌间隙植入含有15μL的腺相关病毒-骨形态发生蛋白4(5×1010 PFU/mL)10 d及14 d,再通过X-gal染色来观察异化骨中有无新血管内皮生成。结果与结论:①骨形态发生蛋白4导致肌束退化并增加C2C12细胞增殖。与其他组相比,FDC组具有较高的阿尔新蓝和番红O染色面积(P<0.05)和较低碱性磷酸酶染色面积(P<0.05);而L6组和其他组相比具有更大的碱性磷酸酶染色面积(P<0.05),但阿尔新蓝和番红O染色面积较小(P<0.05)。②将腺相关病毒-骨形态发生蛋白4吸附的明胶海绵移植到FVB/N-TgN(TIE2-LacZ)182Sato小鼠中会导致异位骨化。③X-gal染色结果显示,在软骨细胞及异化骨中无明显染色,提示Tie2+内皮细胞不参与异位骨化的形成。④结果证实,在腺相关病毒-骨形态发生蛋白4诱导的骨骼肌异位软骨化过程中,成纤维细胞是软骨细胞的主要细胞来源,而肌源性细胞是成骨细胞的主要来源。Tie2+内皮细胞可能不是软骨和骨的细胞来源。

Cat Virus Tied to SARS from New York Times

选注者言:5月24日世界卫生组织解除了香港和广州的旅游警告,同一天,香港和深圳的科学家联合声明在野生动物masked palm civets(果子狸)身上发现了与人类SARS病毒一致的病原体,人类对SARS的战斗胜利越来越近!想起5月的《科技英语学习》上第一篇文章中的一句话…the Canadian are telling them(Chinese in China Town),you dirty Chinese,you eat everything,that’S why

EDT Method for Multiple Labelled Objects Subject to Tied Distances

The success of new scientific areas can be assessed by their potential for contributing to new theoretical approaches aligned with real-world applications.The Euclidean distance transform(EDT)has fared well in both cases,providing a sound theoretical basis for a number of applications,such as median axis transform,fractal analysis,skeletonization,and Voronoi diagrams.Despite its wide applicability,the discrete form of the EDT includes interesting properties that have not yet been fully exploited in the literature.In this paper,we are particularly interested in the properties of 1)working with multiple objects/labels;and 2)identifying and counting equidistant pixels/voxels from certain points of interest.In some domains(such as dataset classification,texture,and complexity analysis),the result of applying the EDT transform with different objects,and their respective tied distances,may compromise the performance.In this sense,we propose an efficient modification in the method presented in[1],which leads to a novel approach for computing the distance transform in a space with multiple objects,and for counting equidistant pixels/voxels.

Epiphanic Revival: Exploring Metallic Finishes on Batik Fabrics in Ghana

Batik fabric is an integral part of the traditional cloth culture of the Ghanaian traditional setting. However, the batik fabric has marginal usage due to its casual visual appearance. This studio practice seeks to explore the epiphanic revival in the use of metallic finishes on batik substrate to create an enhanced visual appearance with embellished aesthetic sensibilities and diversified use. The researchers adopted the studio-based approach of the qualitative design to manipulate handmade tools, techniques (collagraph) and the batik fabrics through experimentation to produce a glittering mercurial batik fabric which is typically an industrial practice. The studio practice took place at the Textile Design and Technology studio, Takoradi Technical University, Ghana. The traditional batik fabric was manipulated through fabric decoration techniques in accordance with studio-based practices. The Addie model was adopted as a methodological approach in the analysis, design, development, implementation, and evaluation processes of the experimentation processes of the study. Findings revealed that the hand techniques used in the production process for the metallic prints produced interesting accidentals finishes and effects that machine work cannot achieve, producing new discoveries of visual enhancements of traditional batik fabric. Traditional batiks became mercurial with glittery effects. The metallic prints on the fabric also changed its consumption pattern from mere casual fabric to classic and cosmopolitan fabric for varied uses suitable for wearable to non-wearable.

Should Home Buying Be Tied to Hukou?

Responding to the recent frenetic rise in house prices,the Central Government in January announced eight new

African Trees May Be Tied to Lemurs' Fate

在非洲的马达加斯加,有些树木的果实只能被狐猴(lemur)吞食,因此狐猴成了这些树木种子的唯一传播者,这些树木的命运也因此而与狐猴紧紧联系在了一起。

Sleep Deprivation Tied to Shifts in Hunger Hormones

睡眠与健康的密切关系是人们早已熟知的生活常识。然而,每天起早贪黑也能变胖?美国科学家最近研究发现:睡眠减少会使刺激食欲的激素(hormones)分泌增多,抑制食欲的激素分泌减少,从而引起进食,使人变胖。这是否让您耳目一新呢?