剑麻纤维改良MgO-GGBS碳化粉质黏土物理力学性质与微观机制

为解决传统固化剂——水泥的能耗高和环境污染大等问题,本研究采用MgO-粒化高炉矿渣(GGBS)碳化加固粉质黏土,采用剑麻纤维改善固化土的抗裂性,探讨了纤维掺量和纤维长度对碳化改良土物理和力学性质的影响。结果表明:在相同纤维长度下,随纤维掺量增加,MgO-GGBS碳化固化土样的体积增长率、含水率和内摩擦角增加,而黏聚力先增加后减小,无侧限抗压强度先增大后减小最终趋于稳定,黏聚力和强度的峰值出现在0.4%纤维掺量处。在相同纤维掺量下,随纤维长度增大,MgO-GGBS碳化固化土样的体积增长率先减小后增大,在长度10 mm时达到最小;含水率几乎不变;强度先增加后趋于稳定,在长度5~10 mm时提升显著;破坏应变增加,但几乎不受纤维掺量影响;碳化含纤维土样的黏聚力与内摩擦角先增加后减小,并在长度10 mm时达到最大。基于试验结果,提出了剑麻纤维改良MgO-GGBS碳化土加固的机理概念图,揭示了碳化土体基于纤维交织作用、固定作用和填充作用的改良机制。用MgO-GGBS-剑麻纤维等低碳材料代替水泥能显著提高碳化固化粉质黏土体的处理效果和抗裂性能。研究成果将对促进工业固废GGBS和农业废弃纤维在加固软弱地基土中的应用提供理论指导,对岩土工程“双碳”目标实现具有重要意义。

GGB短视频与高中数学传统教学的融合

文章采用文献研究法、实验研究法分析了GGB软件对高中数学教学的意义,介绍GGB软件与高中数学传统教学融合的原则及应用策略,并对GGB短视频与高中数学传统教学融合的实践案例进行教学评估。研究发现,与高中数学传统教学模式相比,学生对GGB短视频的可视化教学方式更满意,学习数学的兴趣和热情明显提高,学习效率得到一定程度的提升,充分表明了GGB短视频与高中数学线下教学的融合具有一定的应用和推广价值。

GGB在高一函数教学中的应用研究

新课标指出要加强信息技术与数学教学的融合,有效运用信息技术可以提高课堂效率,培养学生的数学抽象,直观想象等核心素养.GGB作为重要的教辅工具,其动态性、互动性和易操作性等特点,使得函数知识可视化,从而有效突破高一函数教与学的难点.

基于GGB的高中数学可视化教学研究

在信息技术快速发展的背景下,各种数字化技术被广泛应用于教育领域,数字课堂建设突破了传统教学模式的束缚,有效地提高了课堂教学活力。高中数学教师结合数字技术优化教学设计,基于GeoGebra(简称GGB)软件提升数学课堂的生动立体性,发挥GGB软件的可视性优势,搭建动态教学活动,有效地调动学生的学科体验,激发学生的数学学习兴趣。目前,GGB软件凭借诸多教学优势获得了师生的一致认可,在高中数学课堂获得了广泛应用。本文结合高中数学GGB软件可视化教学的优势进行了分析,并提出了具体的教学应用策略,希望可以有效提升高中数学课堂的教学质量。

Research advance in forest restoration on the burned blanks

How to restore the destroyed forest after forest fire is a key question that man must face. This paper reviewed the research situation and history on the forest restoration burned blanks and summed up the research methods used into four scales: seed-bank scale, community scale, ecosystem scale and landscape scale. The new technologies such as GIS & Remote Sensing used to vegetation restoration were also summarized. The strategies and developing trend of vegetation restoration research on burned blanks were discussed.

Landscape change on burned blanks in Daxing'an Mountains

Daxing抋n Mountains was one of the most important forest areas in China, but it was also an area which was prone to suffering forest fire. The catastrophic forest fire that occurred in Daxing抋n Mountains on May 6, 1987 devastated more than 1.33?06 hm2 of natural forests, which leaded to the formation of some mosaic areas with different burn intensities. Two forest farms of Tuqiang Forest Bureau (124?5-122?8E, 53?4-52?5N) were chosen as a typical area to analyze the post-fire landscape change by drawing and comparing the two digital forest stand maps of 1987 and 2000. The landscape lands of forest were classi-fied into 12 types: coniferous forest, broadleaf forest, needle-broadleaf mixed forest, shrub, nursery, harvested area, burned blanks, agricultural land, swamp, water, built-up, grass. The results showed that: 1) The burned blanks was almost restored, some of them mainly converted into broadleaf forest land during the process of natural restoration, and coniferous forest land by the artificial re-forestation, and the others almost changed into swamp or grass land; 2) The proportion of forest area increased from 47.6% in 1987 to 81.3% in 2002. Therefore, a few management countermeasures, such as the enhancing peoples consciousness of fire-proofing and constructing species diversity, were put forward for forest sustainable development.

Theoretical prediction and experimental investigation on formability of tailor-welded blanks

Based on the elastoplastic mechanical properties of the weld and heat affected zone metals obtained by a nanoindentation test, a theoretical calculation model was established for the forming limit diagram（FLD） of tailor-welded blanks（TWBs） on the basis of plastic constitutive relations and Hosford yield criteria. Hemispherical punch bulging tests were performed to verify the FLD theoretical calculation results. The results demonstrated that not only the FLD theoretical calculation of base materials but also that of TWBs had a good agreement with their experiments. Besides, poorer formability of TWBs caused its FLD significantly lower than that of base materials. The theoretical calculation model offers a reliable approach to obtain the specific FLD of TWBs.

基于GGB的高中数学课程可视化教学研究

立足于普通高中数学课程教学,对新教材必修课程中可高效进行可视化教学的内容,以及可视化教学的三个递进层面进行了详细的梳理与分析。为更好地优化高中数学课堂教学,提出了注重设计数学实验,引导学生深入探究、注重数学语言的互译,阐释内容本质、注重经典题目的变式,发展创新思维的可视化教学实施策略,为在各类中学运用GGB可视化教学提供思路和方法。

Determination of Elastoplastic Mechanical Properties of the Weld and Heat Affected Zone Metals in Tailor-Welded Blanks by Nanoindentation Test

The elastoplastic mechanical properties of the weld and heat affected zone metals have comparatively major impact on the forming process of tailor-welded blanks. A few scholars investigated the elastoplastic mechanical properties of the weld and heat affected zone, but they only simply assumed that it was a uniform distribution elastoplastic material different from the base materials. Four types of tailor-welded blanks which consist of ST12 and 304 stainless steel plates are selected as the research objects, the elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals are obtained based on the nanoindentation tests, and the Erichsen cupping tests are conducted by combining numerical simulation with physical experiment. The nanoindentation tests results demonstrate that the elastoplastic mechanical properties of the weld and heat affected zone metals are not only different from the base materials, but also varying between the weld metals and the heat affected zone metals. Comparing the Erichsen cupping test resulted from numerical with that from experimental method, it is found that the numerical value of Erichsen cupping test which consider the elastoplastic mechanical properties of the weld and heat affected zone metals have a good agreement with the experimental result, and the relative error is only 4.8%. The proposed research provides good solutions for the inhomogeneous elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals, and improves the control performance of tailor-welded blanks forming accuracy.

Preparation of heat-resistant aluminum alloy pipe blanks by multi-layer spray deposition

A heat resistant aluminum alloy pipe blank with dimensions of d 700/300 mm×1 200 mm was prepared by the multi layer spray deposition technology. Optical microscopy, X ray diffractometry and transmission electron microscopy were used to analyze its morphologies and microstructures. The results show that the microstructures of the pipe blank are homogeneous and the precipitates are uniformly distributed d 25～70 nm spherical or sphere like Al 12 (Fe,V) 3Si particles, its mechanical properties at room temperature and 350 ℃ after densification by extrusion are σ b=412 MPa, δ =7.6% and σ b=187 MPa, δ =7.6%, respectively. The analyses indicate that the proper match of the motion rates of atomizer and substrate can produce deposited blanks with uniform thickness and relatively high cooling rate.

Teflon-pad shaping process of circular metal blanks into quasi-cup specimens by theoretical and experimental methods

Teflon-pad shaping process of circular metal blanks into quasi-cup specimens is investigated by theoretical and experimental methods in the quasi-static condition. In the experiments, circular metal sheets are formed into the quasi-cup samples by compressing them between a Teflon-filled die and a rigid punch with desirable shape. To investigate influences of different parameters on the forming progress, 12 rigid punches with different dimensions, two blank material types of aluminum and galvanized iron, three blank thicknesses of 0.6, 1.1 and 1.5 mm, and two Teflon-fillers of PVC and polyurethane are used in several experimental tests. In the analytical part, theoretical deformation models of metal blank and Teflon-filler are introduced and based on energy method, energy absorptions by the blank and Teflon-filler are calculated to derive a theoretical formula for predicting total required energy of the forming process. For this purpose, several energy absorption mechanisms are considered in the blank and filler. Furthermore, predictions by theoretical equation are compared with the corresponding experimental tests to study the verity of the calculated formulas. Theoretical and experimental results illustrate change trend of forming energy with respect to blank thickness. Also, the performed forming tests show that when external cone angle of rigid punch with respect to the horizontal direction increases, forming energy increases nonlinearly; and when the depth of spherical part of rigid punch increases, the probability of rupture increases. Additionally, the experiments demonstrate that there is a direct relationship between the forming energy and flow stress of the blanks. Furthermore, experimental observations illustrate that forming energy of a certain blank with PVC Teflon-filler is higher than that of a similar specimen with polyurethane Teflon-filler; but, the probability of wrinkling decreases when PVC Teflon-pad is used as the filler; and it is advantage of PVC Teflon-filler with respect to polyurethane Teflon.

Joint Performance for Laser Cutting-welding of Zinc-coated Tailored Blanks

The process of laser bull welding of zinc-coated steel（SGCD3 and WLZn）blanks was presented.whose edges were prepared by laser cutting.The properties of the butt joints.such as tensile strength.bending,stamping.weld shape,and corrosion-resisant were tested.The experiments of laser cutting and welding were carried ont on a custom-made system designed.which is a set of equipment for wide sheet butt welding based on a laser cutting-welding combination process.The experiments proved the technological feasibility of laser butt welding for thin zinc coated steel sheets whose edges were prepared by laser cutting on the same equipment.

Behaviour of Friction Stir Dissimilar Welded Blanks and The Role of Different Tool Pin Profiles

In this study,the forming behaviour of dissimilar welded blanks was studied.Welded blanks were prepared with friction stir welding processwith different types of tool pin profiles.Welded blanks were developed with fixedfriction stir welding process parameters by varying the tool pin profiles.The forming behaviour of welded blanks were analyzed with the limiting dome height test in biaxial stretch forming condition.The results reveal that the formability of welded joints are made with the square pin tool exhibited a better formabilitybehaviour when compared with other profiled tools,this is due to sufficient amount heat generation and high static volume to dynamic volume ratio.

融合信息技术手段 借助GGB软件落实三教改革

“三教”改革是解决职业教育中“谁来教、教什么、如何教”的问题,在数学课堂教学中融合信息化手段,改变教学方式,落实“三教”改革,借助GGB软件解决空间立体几何表面积的推导和计算问题,以期为一线教学提供参考。

Research on horizontal electromagnetic continuous casting of copper tube blanks

The effect of commercial frequency electromagnetic field on the solidification structure and mechanical propertiesof copper hollow blanks prepared by horizontal continuous casting method was investigated. The results show thatwhen the electromagnetic field is imposed, columnar grains are evidently refined and fine equiaxed grains areobtained in the inner side of the cross-section. Moreover, with the increase of input current, the equiaxed grain regionwidens and the grains distribute more uniformly in the circumferential direction. Meanwhile, the mechanical properties areremarkably improved by the application of electromagnetic field. When the input current is 140 A, the tensile strengthincreases 15% and the elongation increases 10%. However, the electromagnetic field has no effect on the distribution ofmicroelements.

Preparation of tube blanks by atomization deposition process

By using the method of mathematical calculation combined with experiment, the technological conditions of atomization deposition process for making tube blanks with even thickness were studied. The results show that in the case of the substrate rotating and translating simultaneously, when the ratio of the rotation frequency to the translational velocity is very large, and the other deposition conditions are suitable, tube blanks with even thickness and high density can be produced, and the actual deposition efficiency will be highest.

Application of Blank Symbols in Japanese Architecture and Indoor Designs

A symbol is an expression of meaning,while blank symbols express special meanings.By focusing on the application of blank symbols in Japanese architecture and indoor designs,we analyzed the aesthetic principles in Japanese architecture and indoor designs from the perspective of semiotics,such as“Kongji,”“Emptiness,”and“Dying out,”and their minimalist and pure design concepts.Traditional Chinese culture was also further explored,especially the profound influence of the“Chan sect”and the philosophy of“unity of heaven and mankind”on Japanese architecture and designs.This study aims to facilitate the coexistence and mutual appreciation of Chinese and Japanese architectural designs.

用GGB可视化探究一道新高考题

GeoGeBra软件是一款有益于数学教学的软件,将它应用到教学当中有利于激发学生探究知识的兴趣,提高学生动手操作能力及自主思考能力.本文通过用GGB软件将一道新高考题进行可视化动态化演示,让学生去发现探究,将隐性的、看不见的数学知识和数学思维用显性、看得见的形式加以呈现,以帮助学生学会用数学的眼睛看,用数学的思维想,用数学的语言说.

硅灰及矿渣粉对大掺量粉煤灰砂浆力学性能的影响及机理研究

以硅灰和矿渣粉(GGBS)为辅助胶凝材料,使用聚羧酸高性能减水剂,分别研究了硅灰和GGBS对大掺量粉煤灰砂浆抗压强度的影响。通过压汞测试(MIP)、扫描电子显微镜(SEM)以及X射线衍射(XRD)等方法对制备试件的孔结构、微观产物、物相组成进行分析,得到了硅灰和GGBS影响大掺量粉煤灰砂浆强度的机理。结果表明:单掺硅灰的大掺量粉煤灰砂浆的抗压强度随着硅灰含量增加先增大后减小,单掺GGBS的规律与硅灰类似;复掺硅灰和矿渣时,砂浆的强度较其他同龄期组均有一定的提高,二者表现出良好的协同作用;无论是单掺还是复掺,硅灰和GGBS都对大掺量粉煤灰砂浆强度有良好的提升作用。砂浆试件总孔隙率和大孔占比与抗压强度总体呈负相关,强度越高的砂浆试件微观结构越致密,但相比于总孔隙率,毛细孔和大孔占比表现出与抗压强度更好的相关性。当硅灰和GGBS质量分数分别为8%和6%时,砂浆28 d强度最大,为88.05 MPa。

重金属疏浚污泥快速脱水固稳化技术试验

针对我国疏浚污泥处置低效且成本高以及工业固废——高炉矿渣(GGBS)综合利用率低的问题,提出了一种疏浚污泥快速脱水固化稳定化新技术(PHDVPSS),并通过试验系统性地对新技术的实用可行性进行了分析。同时,进一步分析了GGBS对新技术的影响性。分析表明:该技术在脱水效率、固化强度和毒性浸出方面,较传统技术均具有明显优势。仅3 d时间可将底泥含水率降低近50%,90 d处理样品的UCS是传统方法处理的近11倍,而浸出浓度仅约为传统方法的2/3。GGBS添加量增加对新技术处理效果具有显著提高作用,采用30%GGBS时,仅4 d时间可将污泥含水率降低近2/3,在90 d时,VP-GM-3的UCS是VP-GM-1的近12倍,而浸出浓度仅为VP-GM-1的1/3左右。