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针对薄宽带钢冷轧过程中易发多发的局部型中浪瓢曲缺陷,引入非均匀载荷宽度、弹性约束系数及平均张应力建立了屈曲变形的解析计算模型。应用能量最低原理对屈曲变形区域进行搜索求解,得到了局部型中浪屈曲临界条件(包括临界应力、屈曲波长和屈曲波宽),获得了其与非均匀载荷宽度、弹性约束系数、平均张应力的关系,并发现平均张应力是产生局部型中浪的重要影响因素。应用样条有限元方法对局部型中浪进行数值仿真分析,验证了屈曲解析计算方法的正确性。在实验轧机上进行了轧制研究,通过轧制获得了局部型中浪屈曲模态,对实验结果分析得到了相对应的屈曲临界条件,与解析法和样条有限元法结果基本吻合,证明了样条有限元计算方法与解析计算方法的正确性及其工程应用价值。 相似文献
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INFLUENCE OF DAMPING MODELS ON DYNAMIC ANALYSES OF A BASE-ISOLATED COMPOSITE STRUCTURE UNDER EARTHQUAKES AND ENVIRONMENTAL VIBRATIONS
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Structural design simultaneously governed by earthquakes and environmental vibrations has received a lot of attention in recent years.Base-isolated composite structures are typically used in the above-mentioned structural design.The corresponding analysis involves validating structural safety under earthquakes and human comfort under environmental vibrations through a time-history analysis.Thus,a reasonable damping model is essential.In this work,the representatives of viscous damping model and rate-independent damping model,namely the Rayleigh damping model and uniform damping model,were adopted to investigate the influence of damping models on the time-history analysis of such structural designs.The energy dissipation characteristics of the above-mentioned damping models were illustrated via a dynamic test of recycled aggregate concrete specimens.A case study was performed on a base-isolated steelconcrete composite structure.The dynamic responses under the excitation of earthquakes and environmental vibrations were compared using different damping models.The uniform damping model was found to be more flexible than the Rayleigh damping model in dealing with excitations with different frequency components.The uniform damping model is both theoretically advantageous and easy to use,demonstrating its potential in dynamic analysis of structures designed simultaneously governed by earthquakes and environmental vibrations. 相似文献
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Effective vibration recognition can improve the performance of vibration control and structural damage detection and is in high demand for signal processing and advanced classification.Signal-processing methods can extract the potent time-frequency-domain characteristics of signals;however,the performance of conventional characteristics-based classification needs to be improved.Widely used deep learning algorithms(e.g.,convolutional neural networks(CNNs))can conduct classification by extracting high-dimensional data features,with outstanding performance.Hence,combining the advantages of signal processing and deep-learning algorithms can significantly enhance vibration recognition performance.A novel vibration recognition method based on signal processing and deep neural networks is proposed herein.First,environmental vibration signals are collected;then,signal processing is conducted to obtain the coefficient matrices of the time-frequency-domain characteristics using three typical algorithms:the wavelet transform,Hilbert-Huang transform,and Mel frequency cepstral coefficient extraction method.Subsequently,CNNs,long short-term memory(LSTM)networks,and combined deep CNN-LSTM networks are trained for vibration recognition,according to the time-frequencydomain characteristics.Finally,the performance of the trained deep neural networks is evaluated and validated.The results confirm the effectiveness of the proposed vibration recognition method combining signal preprocessing and deep learning. 相似文献
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全球数字3D电影领域的领头羊Real D公司于10月17日与欧洲投资商Terra Firma公司旗下在泛西欧拥有1600块银幕的Odeon院线以及UCI院线签署协议,将于未来2年中在英国、爱尔兰、德国、奥地利以及葡萄牙合作安装500块数字3D银幕. 相似文献
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<正>本刊讯2014年12月23日,由中国建设报社、浙江省住房和城乡建设厅、绍兴市人民政府主办的第十二届中国建筑企业高峰论坛在绍兴市举行。来自全国各地的建筑行业主管部门、行业协会负责人,专家学者及企业代表等300余人齐聚一堂,围绕"创新融合,开放共赢"主题,共同分享了一场建筑行业思想盛宴。中国建设报社党委书记杜久才、社长翟建和中国建筑装饰协会会长李秉仁、中国土木工程协会副理事长刘 相似文献
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<正>阅兵是展示辉煌的时刻,而为这一辉煌采取的所有的标准,不啻也是宝贵的财富,应当成为践行标准的榜样……这个月最令人难忘、最引人自豪、最提振国威的事情,当属"9.3"大阅兵,它有着以往没有的多重的亮点:首次以纪念抗日战争暨世界反法西斯战争胜利为阅兵主题,彰显维护和平是全世界人民共同的愿望。首次邀请外国军队代表参加分列式,体现纪念大会的国际性。首次组织抗战老兵包括国民党老兵参加,体现了对历史的尊重,体现全民族抗战的特色。首次编组英模部队方队受阅,展示中国共产党在抗战中定海 相似文献
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It has been successfully demonstrated can be widely used in nano-photonics applications owing to their flexible wavefront manipulation in a limited physical profile. However, how to improve the efficiency for the transmission light is still a challenge. We experimentally demonstrate that the sine-shaped metallic meanderline fabricated by focus ion beam technology converts circularly polarized (CP) light to its opposite handedness and sends them into different propagation directions depending on the polarization states in near-infrared and visible frequency regions. The beam splitting behavior is well characterized by a simple geometry relation, following the rule concluded from other works on the wavefront manipulation of metasurface with phase discontinuity. Importantly, the meanderline is demonstrated to be more efficient in realizing the same functions due to the suppressed high order diffractions resulted from the absence of interruption in phase profile. The theoretical efficiency reaches 67%. Particularly, potential improvements are feasible by changing or optimizing shape of the meanderline, offering high flexibility in applications for optical imaging, communications and other phase-relative techniques. Additionally, since the continuous phase provided by the meanderline can improve the sampling efficiency of the phase function, it is helpful in realizing high quality hologram. 相似文献
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Dayong Zhang Pu Fan Jinyu Shi Yifan Zheng Jian Zhong Junsheng Yu 《Nano Research》2021,14(5):1319-1325
Non-fullerene organic solar cell(NFOSC)has attracted tremendous attention due to their great potential for commercial applications.To improve its power conversion efficiency(PCE),generally,sequential solution deposition(SSD)methods have been employed to construct the graded vertical phase separation(VPS)of the bulk-heterojunction(BHJ)active layer for efficient exciton separation and charge transition.However,a variety of orthogonal solvents used in the SSD may lead to the unpredicted change in the BHJ morphology and introduce additional defects inside the BHJ bulk thus complicate the fabrication process.Here,a simple oscillating stratification preprocessing(OSP)is developed to facilitate the formation of graded VPS among the BHJ layer.As a result,a significant improvement is obtained in PCE from 10.96%to 12.03%,which is the highest value reported among PBDB-T:ITIC based NFOSC. 相似文献
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Ming Chen Qinnan Zhou Jiantao Zai Asma Iqbal TsegayeTadesse Tsega Boxu Dong Xuejiao Liu Yuchi Zhang Changyu Yan Liang Zhao Ali Nazakat SharelPeisan E CheeTongJohn Low Xuefeng Qian 《Nano Research》2021,14(4):1004-1011
Silicon is a low price and high capacity ancxje material for lithium-ion batteries.The yolk-shell structure can effectively accommodate Si expansion to improve stability.However,the limited rate performance of Si anodes can't meet people's growing demand for high power density.Herein,the phosphorus-doped yolk-shell Si@C materials(P-doped Si@C)were prepared through carbon coating on P-doped Si/SiOxmatrix to obtain high power and stable devices.Therefore,the as-prepared P-doped Si@C electrodes delivered a rapid increase in Coulombic efficiency from 74.4%to 99.6%after only 6 cycles,high capacity retention of-95%over 800 cycles at 4 A·g-1,and great rate capability(510 mAh·g-1at 35 A·g-1).As a result,P-doped Si@C anodes paired with commercial activated carbon and LiFePO4cathode to assemble lithium-ion capacitor(high power density of?61,080 W·kg-1at 20 A·g-1)and lithium-ion full cell(good rate performance with 68.3 mAh·g-1at 5 C),respectively.This work can provide an effective way tofurther improve power density and stability for energy storage devices. 相似文献
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CIG前驱膜叠层方式对CIGS膜成分和结构的影响 总被引:1,自引:1,他引:0
采用中频交流磁控溅射方法制备了三种不同叠层方式的CuInGa(CIG)前驱膜。采用固态法硒化,获得了CIGS吸收层。采用SEM和XRD观察和分析了薄膜的成分、组织结构和表面形貌。着重分析不同叠层方式的CIG前驱膜对CIGs吸收层薄膜成分、晶体结构的影响。结果表明,三种叠层方式的前驱膜都可以获得成分均匀、结构一致的CIGS吸收层薄膜。Ga可以有效抑制In2Se挥发相生成,保持成分的稳定性。以CuGa(top)/CuIn(bottom)形式的前驱膜有利于形成紧密晶粒排列的CIGS。 相似文献
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Linsheng Huang Xiaowen Zhou Rui Xue Pengfei Xu Siliang Wang Chao Xu Wei Zeng Yi Xiong Hongqian Sang Dong Liang 《纳微快报(英文)》2020,(3):199-217
A multi-dimensional conductive heterojunction structure,composited by TiO2,SnO2,and Ti3C2TX MXene,is facilely designed and applied as electron transport layer in efficient and stable planar perovskite solar cells.Based on an oxygen vacancy scramble effect,the zero-dimensional anatase TiO2 quantum dots,surrounding on two-dimensional conductive Ti3C2TX sheets,are in situ rooted on three-dimensional SnO2 nanoparticles,constructing nanoscale TiO2/SnO2 heterojunctions.The fabrication is implemented in a controlled lowtemperature anneal method in air and then in N2 atmospheres.With the optimal MXene content,the optical property,the crystallinity of perovskite layer,and internal interfaces are all facilitated,contributing more amount of carrier with effective and rapid transferring in device.The champion power conversion efficiency of resultant perovskite solar cells achieves 19.14%,yet that of counterpart is just 16.83%.In addition,it can also maintain almost 85%of its initial performance for more than 45 days in 30–40%humidity air;comparatively,the counterpart declines to just below 75%of its initial performance. 相似文献
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Kai Wu Jin Yi Xiaoyu Liu Yang Sun Jin Cui Yihua Xie Yuyu Liu Yongyao Xia Jiujun Zhang 《纳微快报(英文)》2021,(5):107-117
Aqueous zinc ion batteries show prospects for next-generation renewable energy storage devices.However,the practical applications have been limited by the issues derived from Zn anode.As one of serious problems,Zn dendrite growth caused from the uncontrollable Zn deposition is unfavorable.Herein,with the aim to regulate Zn deposition,an artificial solid–electrolyte interface is subtly engineered with a perovskite type material,BaTiO3,which can be polarized,and its polarization could be switched under the external electric field.Resulting from the aligned dipole in BaTiO3 layer,zinc ions could move in order during cycling process.Regulated Zn migration at the anode/electrolyte interface contributes to the even Zn stripping/plating and confined Zn dendrite growth.As a result,the reversible Zn plating/stripping processes for over 2000 h have been achieved at 1 mA cm?2 with capacity of 1 mAh cm?2.Furthermore,this anode endowing the electric dipoles shows enhanced cycling stability for aqueous Zn-MnO2 batteries.The battery can deliver nearly 100%Coulombic efficiency at 2 Ag?1 after 300 cycles. 相似文献
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This study investigated the effect of multi-step heat treatment on the microstructure, mechanical properties and fracture behavior of thick 15 Co-12 Ni secondary hardening steel. As-quenched sample was found to have elongated prior austenite grain(PAG) and coarse lenticular martensitic structure. On the other hand, heat-treated sample was observed to have fine lenticular martensitic structure due to fine PAG size and a lot of nano-sized carbides. Also, after heat treatment, nano-scale reverted austenite film was formed at the martensite interfaces. The heat-treated sample showed 2.47 GPa superior tensile strength and superior elongation of about 12 %. The high strength was mainly due to fine block size and high number density of nano-sized carbides. The average value of plane strain fracture toughness(KIC) was 29.3 MPa m1/2, which indicated a good fracture toughness even with the high tensile strength. The tensile fracture surface was observed to have ductile fracture mode(cup-and-cone) and the formation of about ~1 μm ultra-fine dimples. In addition to this, nano-sized carbides were observed within the dimples.The findings suggested that the nano-sized carbide had a positive effect not only on the strength but also on the ductility of the alloy. The fractured surface after toughness test, also showed ductile fracture mode with a lot of dimples. Based on the above results, correlation among microstructural evolution,deformation and fracture mechanisms along the heat-treatment was also discussed. 相似文献
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<正>4月8日,中国标准化杂志社编委会会议暨2015年年会在北京汉能控股集团召开,中国标准化协会理事长、中国标准化杂志社编委会名誉顾问纪正昆,中国标准化研究院院长、编委会主任马林聪,国家质检总局新闻办里新,国家标准委办公室主任邓志勇等出席会议并讲话,来自中国标准化杂志社编委会和理事会成员等70多人出席了此次会议,会议由马林聪院长主持。中国标准化协会理事长纪正昆对杂志社编委会提出明确要求,他说:我们现在遇到了一个非常难得的发展机遇,杂 相似文献
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现如今,数码单反已经不是什么稀罕玩意,只要稍微学习一下,谁都能拍出前实后虚的"糖水片"或者卖弄一下机器的高感光度。在手持单反的庞大人群中。如何体现自己的个性?如何表现自己的创作欲望?奥林巴斯正好为追求个性和创意的人士推出了E-30,这款中档数码单反相机具有一个名为"Art Filter(艺术滤镜)"的功能,可以帮你直接拍出带有艺术风格的照片,无需再做后期处理。本刊编辑有幸接到了奥林巴斯的邀请,到港澳地区试用了一把,现在就和大家好好说说这个"艺术滤镜"…… 相似文献