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1.
    
Response of brittle plate‐like structures such as glass panels to impact loads has been the subject of many research studies. Different compositions of glass are used in wide variety of applications in daily life. Of interest in this study are the glass panels that are used in consumer electronics devices such as mobile phones, tablets, and televisions that help to protect the displays from every day wear and tear. Therefore, the requirement of this glass to resist scratches, drop impacts, and bumps from everyday use leads to the importance of investigation of the glass response under dynamic impact loading. Ball drop test is a widely accepted test for impact reliability in the industry. The test specifies the impact energy threshold as a qualification and prediction metric. Use of energy as the key parameter in impact testing is limited, because it does not account for the time spent in contact during the impact event. This study attempts to establish a reliable metric for impact testing based on a momentum change. The deformation and the strain of the glass will be obtained by the digital image correlation system, while the rebound velocity will be measured with the high‐speed cameras. The global and local measurements are conducted to verify the accuracy of the experimental results. Finite element analysis is conducted using ABAQUS to provide a comprehensive understanding of the dynamic response of the glass. Constitutive relationship for a tape, a hyperelastic material, is developed in this study. Good correlation in deflection time history is obtained between the measurements and predictions.  相似文献   

2.
    
Strength is one of the most important properties of cover glass. In this study, fracture analysis is used to classify the breakage mode of cover glass into four typical modes. Moreover, the mechanism and evaluation method of each mode are investigated. Consequently, a chemical strengthening design with high compressive stress (CS) and low center tension (CT) is obtained. In addition, processing design is determined to be an important factor. Fining of edge processing and surface polishing after chemical strengthening are shown to enhance the edge and surface strength, respectively.  相似文献   

3.
    
Cover glass in commercial handheld devices is now evolving from flat (2D) to curved (3D) shapes. For example, some commercial devices have utilized sled‐shape cover glass, 1 which partially covers long edges of the device. According to the patents published by key handheld manufacturers, 2 , 3 we can expect more variety of 3D shaped cover glass for handheld devices in the market. In this study, we have focused on the reliability of 3D cover glass when it is dropped to a rigid surface. The key parameters under study are the corner/edge bend radius and angle of the cover glass, which determines the 3D shape of the cover glass. To achieve this goal, we developed a finite element model to simulate the drop 4 - 13 of a handheld device with 3D‐shaped glass. The model uses explicit algorithm to simulate the high speed impact on the device during the drop test. The glass performance was evaluated based on contact force between the glass and the ground and maximum principal stress in the glass. We showed that to avoid severe damage because of first impact between the glass and the ground, the bend angle of 3D glass has to be in the range between 0 and 45°. For drop angles of 45° and higher, with the proposed glass bend angle, the impact can be taken over by the edge of the back cover of the device. In addition, we showed that optimum glass bend radius is in the range of 3.8 mm and larger. This is required to reduce stress in glass because of impact. The approach and conclusions from the current study can serve as a general guideline to improve the 3D cover glass reliability of a handheld device.  相似文献   

4.
    
Abstract— The encapsulation of organic light‐emitting layers is a key development item on the road‐map to OLED commercialization and needs to be resolved in order to compete with the incumbent LCD technology. DuPont? Drylox? cover glass is a product developed by DuPont Displays to improve the features of the OLED encapsulation solution. Thin displays, low design cycle time, and substantial reduction in encapsulation cost are the driving forces for the product improvement. This paper discusses permeation theory, describes a manufacturing method, and documents the performance characteristics achieved to date.  相似文献   

5.
本文通过从自然色彩再现到主观色彩表现的转变过程的描述,将《色彩风景写生》课程最核心的方法提炼出来,希望写生的目的在于培养一种能力,一种控制画面的构图、形体、结构、空间、色调诸关系的能力。学生具备了这种能力,也就具备了一种语言方式,这种语言方式便是创造绘画艺术作品最基本的途径。  相似文献   

6.
论文首先对中国古玻璃①艺术形式进行分析,从宏观上对中国古代玻璃技术的发展进行整体阐述,指出古代中国的玻璃行业发展缓慢的原因和现代玻璃艺术的出现与大发展。本文着重于从玻璃艺术工艺入手,解析历史中的工艺形态、技术应用现象,结合其工艺自身的特点和艺术的形式规律,对传统工艺的再开发,挖掘其潜力为今天服务。现代的工艺形式是基于古老的传统技术手法之上的,是传统工艺的延续和变革。  相似文献   

7.
利用概率方法和频谱理论,给出布尔函数满足强扩散准则的一个新的等价判别条件,并根据强扩散准则与扩散准则之间的关系,得到满足k次强扩散准则的布尔函数的2种构造方法。结合具有平衡性和相关免疫性的布尔函数的谱特征,给出缸欺骗免疫秘密共享定义函数的谱判别条件。  相似文献   

8.
基于遥感和GIS的东亚土地覆盖年际变化研究   总被引:3,自引:0,他引:3       下载免费PDF全文
土地覆盖的年际变化是以土地覆盖的宏观分布模式为基准,在外界驱动因子的作用下发生的年与年之间的变化,因此,为揭示东亚地区土地覆盖的年际变化特征,首先选取东亚地区时相一致的不同空间分辨率(1km和8km)的NDVI影像进行了非监督分类,并总结了东亚土地覆盖的宏观分布模式,然后以时间序列的8kmAVHRRNDVI数字影像为基础,应用跨平百分率分析方法生成每年5-9月距平百分率分级影像,并以该影像为基础分析总结了东亚土地覆盖的年际变化特征,结果显示,该方法及其揭示的现象比较客观地反映了东亚土地覆盖年际变化特征。  相似文献   

9.
玻璃缺陷自动检测已成为提高玻璃质量的重要技术之一,它在检测出不合格玻璃产品的同时,还能将缺陷信息传递给玻璃生产的各个流程,再对各个环节加以改进。为能够生产出高质量的玻璃和准确地获取玻璃缺陷信息,提出了一种基于光栅的玻璃缺陷检测和三值化的处理方法,不但能够检测出微小缺陷,还能有效地检测出玻璃的波筋缺陷。  相似文献   

10.
基于MODIS数据的我国天山典型区积雪特征研究   总被引:1,自引:0,他引:1  
准确监测天山地区积雪面积和积雪日数对合理利用水资源及分析区域气候变化有重要意义。MODIS每日积雪产品可以为大面积快速积雪制图与监测提供依据,但因云量较高成为其应用的瓶颈。利用结合MODIS产品的时间与空间信息有效地减少了云对MODIS积雪产品的影响,并利用改进的MODIS积雪数据和DEM分析2002~2009年天山地区积雪面积和积雪日数的变化特征。结果表明:积雪频率总体上随着海拔升高而增大;不同坡向积雪面积差异明显,西北坡积雪覆盖率最高,北坡、西坡和东北坡次之,南坡和东南坡的积雪覆盖率最低;2006~2008年研究区积雪面积出现低值,年内最大积雪面积呈逐年减少的趋势;随着海拔下降,积雪日数逐渐变小,天山南部地区积雪日数仅为40 d以下;积雪日数大的区域年际积雪日数变化相对稳定,积雪日数少于40 d的区域积雪日数的变异系数最大,年际积雪日数变化不稳定。  相似文献   

11.
The connected vertex cover problem is a variant of the vertex cover problem, in which a vertex cover is additional required to induce a connected subgraph in a given connected graph. The problem is known to be NP-hard and to be at least as hard to approximate as the vertex cover problem is. While several 2-approximation NC algorithms are known for vertex cover, whether unweighted or weighted, no parallel algorithm with guaranteed approximation is known for connected vertex cover. Moreover, converting the existing sequential 2-approximation algorithms for connected vertex cover to parallel ones results in RNC algorithms of rather high complexity at best.In this paper we present a 2-approximation NC (and RNC) algorithm for connected vertex cover (and tree cover). The NC algorithm runs in O(log2n) time using O(Δ2(m+n)/logn) processors on an EREW-PRAM, while the RNC algorithm runs in O(logn) expected time using O(m+n) processors on a CRCW-PRAM, when a given graph has n vertices and m edges with maximum vertex degree of Δ.  相似文献   

12.
Using density functional theory-based calculated formation and reaction enthalpies, we have examined the relative stability of a large number of likely oxide phases of typical ODS steels based on the Fe–Cr–Al–Ti–Y–O system. Calculated formation and reaction enthalpies are in good agreement with available measured values. The relatively more negative formation enthalpies of Y2O3, Y2TiO5, Y4Al2O9, Y2Ti2O7 and YAlO3 oxides show them to be more stable corroborating with their observation in the microstructure of ODS steels. Analysis of reaction enthalpies, guided by convex-hull consideration, gives a mechanism by which reaction of Y2O3 with Al2O3 for the formation of YAlO3, Y4Al2O9, and Y3Al5O12 and reaction of Y2O3 with TiO2 for the formation of Y2TiO5 and Y2Ti2O7 are favored over other likely oxides, such as, those based on Y–Fe–O, Y–Cr–O and Fe–Cr–O.  相似文献   

13.
FD集最优覆盖多项式时间求解算法的研究   总被引:1,自引:0,他引:1  
本文在详细分析了FD集的最小覆盖和最优覆盖的结构特性基础上,提出并讨论了一个最小覆盖成为最优覆盖的条件及一个最优覆盖珠属性集构成的特点,相应的引理和定理。最后给出一个求FD集最优覆盖的多项式时间算法。  相似文献   

14.
通过对黑陶瓷封装工艺的研究,得到了理想的封装工艺条件,并建立了一条稳定性好、成品率高的封装工艺线。同时成功地封装了一些型号的电路,性能优异,通过了高可靠封装质量考核。  相似文献   

15.
设计了一款加强型共面蜂窝,通过采用数值仿真分析的方法对该蜂窝的面内压缩行为进行了数值模拟。并且通过模具制造了加强型共面蜂窝与普通蜂窝的试验件,通过准静态压缩试验对比了两种蜂窝的吸能特性,并且验证了仿真手段的可靠性。仿真和实验结果表明,该类型加强型蜂窝吸能特性能比普通蜂窝共面方向压缩有很大提升。  相似文献   

16.
线型无线传感器网络是一种较为特殊的无线传感器网络类型,其传感器节点的分布区域接近线型区域。在满足监控性能的要求下,通过调度节点,让部分节点工作,其余节点休眠,可有效延长系统生命期。现有的调度算法在线型无线传感器网络下的性能不是很好,针对线型无线传感器网络的特点,提出了异步调度算法和同步调度算法。仿真实验表明,同步调度算法得到的覆盖集的大小为异步调度算法的76%左右,平均覆盖度接近理想最优情况。  相似文献   

17.
基于2000年~2010年的MODIS/Terra积雪8d合成数据(MOD10A2)与DEM数据,通过计算和分析不同高程带、不同坡向和不同坡度的积雪覆盖率,研究了新疆玛纳斯河山区雪盖的年内变化特征。结果表明:①研究区平均积雪覆盖率最高为一月中旬的67.8%,最低为七月中旬的11.9%,年内变化总体上呈V字型,积雪分布与气温关系密切;②可将研究区雪盖年内分布情况归纳为1600m以下、1600m~3800m和3800m以上共三个高程带,各高程带内雪盖分布的年内变化较为相似,不同高程带则差异明显。从年内波动情况来看,低海拔地区年内波动幅度最大,随着海拔上升,波动幅度逐渐减小;③3800m以下各坡向和坡度地区积雪覆盖率均表现为一月最高,七月最低,四月和十月介于二者之间,而3800m以上地区积雪覆盖率全年最高值则出现在四月和十月;④各坡度和坡向区域雪盖的年内变化与所在高程带的总体情况基本相似,说明坡度和坡向对雪盖分布的影响是在高程影响的基础上产生的。  相似文献   

18.
覆盖算法在文本分类中的应用   总被引:1,自引:0,他引:1  
介绍了文本分类的基本过程以及朴素贝叶斯和K近邻算法等基本分类方法,给出了基于覆盖的构造性神经粤络分类算法,并将其与朴素贝叶斯和KNN作了实验比较。结果表明,该算法具有较好的分类性能,适合于处理大规模的文本分类任务,从而有效地克服了传统文本分类算法的不足。  相似文献   

19.
In float glass manufacturing, the glass is often stained with tin, which will result in deficient quality. The amount of stained tin is related to five factors: temperature, oxygen content in tin liqnid, bath pressure, total amount of protecting gas, and the thickness of the glass. On the basis of the experimental data, and through system reconstruction analysis, each factor's value range where there is not any tin stain on the float glass is found.  相似文献   

20.
对象依赖集合性质的研究   总被引:2,自引:1,他引:2  
在复杂对象模式的规范化设计中,对象间的语义关系起了重要作用。然而,目前还没有关系的研究报告,讨论了对象依赖集合的一些性质,首先概括了基本概念和性质;然后给出并证明获取一个OD集合所有关键字的JINGSI算法;最后证明要作为复杂对象模式规范化设计的MIMI算法输入的OD集合的特性,并基于此改进复杂对象模式规范化设计。  相似文献   

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