Study on dynamic response of embedded long span corrugated steel culverts using scaled model shaking table tests and numerical analyses

A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culverts due to strong earth-quakes like the 1995 Hyogoken-nanbu earthquake. The dynamic strains of the embedded culvert models and the seismic soil pressure acting on the models due to sinusoidal and random strong motions were investigated. This study verified that the cor-rugated culvert model was subjected to dynamic horizontal forces (lateral seismic soil pressure) from the surrounding ground, which caused the large bending strains on the structure; and that the structures do not exceed the allowable plastic deformation and do not collapse completely during strong earthquake like Hyogoken-nanbu earthquake. The results obtained are useful for design and construction of embedded long span corrugated steel culverts in seismic regions.

Finite Element Analyses and Instrumentation Layout for Single Coil Testing of TF Coils in HT-7U

The HT-7U tokamak is a magnetically-confined full superconducting fusion device, consisting of superconducting toroidal field (TF) coils and superconducting poloidal field (PF) coils. These coils are wound with cable-in-conductor (CICC) which is based on UNK NbTi wires made in Russian '. A single D-shaped toroidal field magnet coil will be tested for large and expensive magnets systems before assembling them in the toroidal configuration. This paper describes the layout of the instrumentation for a superconducting test facility based on the results of a finite element modeling of the single coil of toroidal magnetic field (TF) coils in HT-7U tokamak device. At the same time, the design of coil support structure in the test facility is particularly discussed in some detail.

Correlation and Regression Analyses on the Washback effects of Achievement Oral Test on College English Learning

The purpose of this study was to investigate how washback effect of a reformed test influenced students'perspectives in their spoken English learning. This study was expected to enrich the existing literature in testing washback in English as a foreign language context.Findings indicate that the adding of oral part in achievement test does have a positive washback effect on students'learning. However, such a washback effect on students'learning is quite superficial and limited.

Diagnostic Analyses and Numerical Modeling of Explosive Cyclone over Northwestern Pacific on January 11-13,2012

In this paper,we use FNL grid data obtained from the National Centers for Environmental Prediction(NCEP)to analyze an explosive cyclone(EC)that occurred over the northwestern Pacific Ocean from January 11 to 13,2012.To simulate the EC,we used the Weather Research and Forecasting model(WRFV3.5).The cyclone outbreak occurred east of Japan from January 11 to 12 and weakened near the Kamchatka Peninsula on January 13.The analysis results show a distinct frontal structure,in which the high potential vorticity(PV)of the upper troposphere extends downward to the surface,which can facilitate EC development.A low-level jet stream develops with the EC,which can lead to more distinct convergence.The results of sea surface temperature(SST)sensitivity tests suggest that changes in the SST can affect cyclone intensity,but have little effect on its path.When small changes are made to the SST,the air pressure at the cyclonic center responds more distinctly to an increased SST than a decreased SST.The results of our latent heat release test suggest that diabatic heating processes lead to maximum PV values in the lower troposphere.Latent heat is also one of the important factors influencing EC development.

Thermal Activation Analyses of Dynamic FractureToughness of High Strength Low Alloy Steels

A formula is derived for determining the influence of temperature and loading rate on dynamic fracture toughness of a high strength low alloy steel (HQ785C) from thermal activation analysis of the experimental results of three-point bend specimens as well as introducing an Arrhenius formula. It is shown that the results obtained by the given formula are in good agreement with the experimental ones in the thermal activation region. The present method is also valuable to describe the relationship between dynamic fracture toughness and temperature and loading rate of other high strength low alloy steels.

Statistical Analyses and Geotechnical Evaluation of Nubia Sandstone, Golden Triangle Area, Egypt

Great efforts had been made to use indirect non-destructive tests in the geotechnical evaluation of rocks, especially sandstones, employing different empirical equations. However, most of these equations have been derived from hard and compacted sandstones data;therefore, the focus of this research is on weak and weakly compacted sandstones, aiming firstly to obtain empirical equations for estimating their characteristics, secondly to demonstrate and visualize the correlations between the studied variables, and finally to cluster the studied samples based on their characteristics. To attain these aims, twenty oriented block samples were collected from Nubia sandstone, central Eastern Desert, Golden Triangle area, Egypt. These samples were prepared and tested according to standard test methods, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), Schmidt rebound number (SRN), porosity (n), bulk density (ρ), and ultrasonic P-wave velocity (UPV). The loss on ignition (LOI) was also employed as a physicochemical test for classifying the studied samples and indicating pores filling materials. The results revealed that these sandstones are characterized mainly by high n, low ρ, and low UPV values and these give an indication of weakly compacted and weakly cemented sandstone with shallow burial diagenetic conditions. Based on UCS and elastic modulus values, these sandstones are mainly classified as very low strength and highly yielding rocks. The results of regression analysis show satisfactory correlations between physical and mechanical characteristics, indicating the suitability of obtained empirical equations to deduce these properties. Principal component analysis revealed that the LOI, BTS, SRN, and USC have a positive correlation to each other and weakly correlated with ρ and UPV, which positively correlated to each other and negatively correlated to n. The results of agglomerative hierarchical clustering revealed that the studied samples can group into three main clusters depending on their USC, LOI, and n values.

TESTBED在某型高炮火控软件测试中的应用

研究了黑盒功能测试和结构覆盖测试,定义了各种覆盖率指标及指出其适用范围,根据覆盖率准则的包含关系,提出了装备定型中关键软件的测试策略;针对某型高炮系统的组成与特点,设计和搭建了其火控软件配置项测试的仿真测试平台;介绍了TESTBED插装选项中两种基本覆盖率信息压缩方式,并通过插装模板和插装代码的适应性改造,建立了一种新的覆盖率信息压缩形式BYTEMAP,克服了BITMAP插装方式对被测火控软件实时性的影响,利用系统预留的串行通信端口,输出了测试的覆盖率信息,实现了嵌入式火控软件的覆盖率测试和分析;测试结果表明:根据软件规约所设计的测试用例和覆盖率分析所补充的测试用例充分有效,达到了预期的测试效果.

Earthquake simulation test of circular reinforced concrete bridge column under multidirectional seismic excitation

Structures behave multi-directionally when subjected to earthquake excitation. Thus, it is essential to evaluate the effect of multidirectional loading on the dynamic response and seismic performance of reinforced concrete bridge columns in order to develop more advanced and reliable design procedures. To investigate such effects, a 1/4 scaled circular reinforced concrete bridge column specimen was tested under two horizontal and one vertical components of a strong motion that has long duration with several strong pulses. Damage progress of reinforced concrete columns subjected to strong excitation was evaluated from the test. The test results demonstrate that the lateral force response in the principal directions become smaller than computed flexural capacity due to the bilateral flexural loading effects, and that the lateral response is not significantly affected by the fluctuation of the axial force because the horizontal response and axial force barely reached the maximum simultaneously due to difference of the predominant natural periods between the vertical and the horizontal directions. Accuracy of fiber analyses is discussed using the test results.

A GIS Pre and Post Processing Contribution to a Multi Techniques Test Survey for an Ancient Railway Restoration in the Brembana Valley

Stemming from the renewed desire to requalify the former Brembana Valley railway route (inside one of the valleys of the Province of Bergamo and close to the important city of Milan), from Bergamo to Villa d’Almè, in 2017, the Bergamo Transport Company and other partners have signed a memorandum of understanding. They have also entrusted a project company to develop a technical and economic viability study, which would be an update of a preliminary one presented in 2009. A private proposal for the realization of a test survey, useful for the required engineering project, has been submitted to the project company and accepted. For this reason, a team, comprising different companies, and among them also the Geomatics group at the University of Bergamo, was formed so as to perform this task and develop it in a degree thesis. The aim of the test survey is to evaluate a joint use of the new available technologies, so as to possibly get faster, more economic and thorough results, by performing a 3D metric analysis over two sub-areas selected along the route. The paper describes this experience and the achieved results. In particular, the areas of interest in the test project have been analyzed first thing with a GIS software and then surveyed with a multi-sensor approach, i.e. terrestrial laser scanner, GNSS techniques and UAV. The final integrated results allowed providing a metric model of the morphological and urban aspect for the territorial layout, useful also for further advanced GIS analyses. The analysis of the reached precisions has provided satisfactory results which agree with the metric requirements of the project. Further meaningful considerations can be derived from this test survey: the implementation of different techniques has helped to overcome problems due to hidden parts in complex objects, it has allowed to provide a faster survey and to test different technologies and software packages. The results have been quite satisfactory.

1976—2021年纳木错和色林错湖泊面积变化及驱动因素分析

湖泊在水循环和水平衡中发挥着重要作用,对气候变化极其敏感。分析青藏高原湖泊面积变化及驱动因素,对揭示高原气候变化具有重要意义。文章通过解译1976—2021年Landsat系列遥感影像,获取纳木错和色林错湖泊水体面积,利用数理统计方法分析湖泊水体面积及气温、降水的变化特征,并探讨了气温和降水量对湖泊面积变化的影响。结果表明:1.纳木错和色林错湖泊面积总体均呈显著增长趋势(P<0.01),增幅分别为2.90%和36.30%,分别于2001年和2002年发生突变,其中,纳木错湖泊面积变化波动较小(CV=1.64%),色林错湖泊面积波动幅度较大(CV=12.65%)。2.纳木错和色林错流域多年平均降水量和气温均呈现显著增加趋势。3.纳木错湖泊面积变化与气温和降水量呈显著正相关,受降水与气温的共同影响;色林错湖泊面积变化与气温呈显著正相关,与降水量无显著相关性,气温增加引起的冰雪加速融化是色林错急剧扩张的主要原因。相关结果为高寒地区湖泊演变机制的研究及生态环境保护措施的制定提供理论依据。

徐州土山二号汉墓中白灰材料的科学研究

徐州土山二号墓是近年来发掘的一座重要的东汉早期诸侯王级墓葬,并成功入选2020年度全国十大考古新发现。该墓葬属于砖室墓,墓葬中多处、大量使用白灰的情况为同时期墓葬中所罕见,代表着当时高度发达的白灰生产和应用的工艺水平。白灰是中国古代应用最为广泛的胶凝材料之一,但目前针对它的科学研究仍存在着较大的空白。为深入探究土山二号白灰的成分和功用,对该墓中白灰的使用情况进行了调查,并利用X射线衍射分析(XRD)、傅里叶变换红外光谱分析(FTIR)、热重-差示扫描量热分析(TG-DSC)、扫描电镜显微观察(SEM)、碘淀粉实验和多孔材密度、孔隙率、吸水率测试、X射线荧光光谱分析(XRF)等多种技术手段对各类白灰样品进行了分析测试。研究结果显示,土山二号墓中的所有白灰样品均由天然石灰石经人工煅烧后生成,且没有添加骨料成分,反映出汉代时古人烧制石灰的工艺已经十分纯熟;白灰的原材料都来源于利用徐州本地青石类高钙天然材料烧制的石灰,碳酸钙含量到达了85%以上,说明当时在煅烧石灰时已经具有优选原材料的意识;石灰在墓中具有多种用途,包括墓室砖石墙体的砌筑灰浆、墓室踢脚线和顶券的装饰抹灰及棺内墓主尸身下防腐吸潮的衬灰等,说明当时人们已经对石灰的性质有了相当的了解并能够将之善加利用;样品由于与外界自然环境接触,发生了明显的侵蚀和风化,亟需进行加固保护处理。该研究对于了解中国东汉时期古人对石灰性能的认识及其在生产生活中的应用等科技文明发展状况具有重要意义,也为后续相关文物的保护提供了科学的参考。

基于CFD-DPM模型的T型网式过滤器冲蚀特性模拟与分析

为分析滤网冲蚀情况,采用多孔阶跃模型和滤网缩尺模型,结合CFD-DPM两相流模型通过主因素分析方法对滤网冲蚀速率规律进行数值模拟分析与预测,探求整体不同区域滤网的冲蚀效应情况,并通过基于正交试验的多因素主效应分析得出各因素对最大冲蚀速率的影响显著性大小.结果表明:在一定范围内最大冲蚀速率与颗粒粒径呈负相关而与质量流率、流速呈正相关;滤网表面中滤孔面普遍比迎水面更易受冲蚀破坏,背水面几乎不受冲蚀影响;颗粒粒径、质量流率对冲蚀高发区域范围大小影响较小(面积增幅为15.0%~16.7%),而流速对其影响较明显(面积增幅为50.0%);显著性检验中,流速、质量流率、颗粒粒径对最大冲蚀速率的P值分别为0.01280,0.00269和3.712×10^(-9),均呈显著性相关.

乳粉中沙门氏菌检测能力验证分析

为证实实验室微生物检验人员对沙门氏菌的检验能力、提高实验室检测水平、增强实验室综合竞争力,实验室参加了中国食品药品检定研究院组织的NIFDC-PT-323乳粉中沙门氏菌检验能力验证。根据作业指导书和GB 4789.4—2016《食品安全国家标准食品微生物学检验沙门氏菌检验》对样品编号为7号和59号的2份能力验证样品进行处理和检验。编号7样品未检出沙门氏菌,编号59样品检出沙门氏菌,能力验证结果为满意,顺利完成能力验证试验。

邻近隧道爆破振动响应研究

由于新建隧道与既有隧道之间距离较近,开挖爆破产生的地震波会危及既有隧道衬砌结构的安全和稳定,笔者应用现场监测和数值分析两种手段对此进行了分析研究,得出了一些有意义的结论。

质构仪分析法在面条品质评价中的应用

该文阐述了质构仪分析法在面条品质研究中的应用，介绍了主要的测试模式和各种模式在面条测试时所选用的测试程序和探头类型，以及相应参数的设定和其他测试条件的设置，给科研工作者客观评价面条品质提供了一定的参考依据。

水力喷射侧钻径向微小井眼技术

为了验证水力喷射侧钻径向微小水平井眼技术的可行性,在胜利油田进行了现场试验。测试研究了不同排量下的高压软管沿程压耗,并根据设计的多孔喷嘴,测试了该喷嘴的自进力。结果表明,高压软管内压耗较大,排量、前后向喷嘴流量比和井筒直径对喷嘴自进力影响较大,为施工时的水力参数设计及泵压预测提供了理论依据。在制定现场施工工艺的基础上,在胜利油田J17 1井进行了现场试验,在井深861.5和864.8m处两个平面上共喷射钻出了4个孔眼,一个长度为20m,其余3个为50m,达到了预期目标。现场试验验证了连续油管水力喷射侧钻径向水平井系统的技术可行性,为老井改造和低渗油藏增产提供了一种新的技术途径。

露天采煤机工作装置的模拟截割试验

在滚筒式露天采煤机工作装置的模拟截割试验的基础上，着重论述了模拟工作装置、模拟煤岩试件、信号分析和数据处理等方面的理论和实践。

科技论文中正交试验结果分析方法的使用

目前科技论文中对正交试验结果的分析大多仅采用极差分析法,而使用方差分析法的只占到18%。其原因,一方面是由于使用方差分析法既复杂计算量又大,另一方面也由于受某些学科习惯做法的影响,更主要的是一些审稿人把关不严。使用方差分析法不仅是对正交试验结果准确分析的保证,而且是检验试验结果是否可靠的重要方法。建议编辑人员必须要求对正交试验结果做方差分析。

质构仪穿刺试验检测冬枣质地品质方法的建立

【目的】丰富鲜食枣果实品质评价的内容,为合理指导生产、建立标准化、统一化的鲜食枣果实质地评价方法提供理论依据和技术手段。【方法】采用质构仪质地整果穿刺法进行试验,通过对不同来源的冬枣进行质地检测、Macro程序编辑和测得数据的方差分析,建立一套适合鲜食枣果实的质地检测方法。【结果】主要试验参数为:采用完整的冬枣为试验对象,每果取最大横径处阴阳面2个部位测定(取平均值),各样品随机取20个(以上)果实进行测定;采用P/2n针状探头(直径2 mm),测前速度5 mm.s-1,贯入速度1 mm.s-1,测后速度5 mm.s-1,最小感知力5 g,穿刺深度小于最小样品的果肉厚度(冬枣,5 mm),感应力阈值2 g;通过设定的Macro程序,可在所得演示曲线中得到:果皮强度(g)、果皮破裂深度(mm)、果皮脆性(g.s-1)、果皮韧性(g×s)、果肉最大硬度(g)、果肉平均硬度(g)和果肉匀质指数等参数。【结论】该方法能够检测出不同生产园、不同含水量和不同贮藏时间冬枣的质地差异,同样适用于其它鲜食枣品种以及其它带皮食用的小型水果的质地分析。