共查询到19条相似文献，搜索用时 78 毫秒
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针对脆性材料偏心受压构件的力学强度性能安全分析,本文分别研究了受拉、受压两种破坏状态。针对受拉破坏,主要通过减小偏心距来控制,并通过计算得到了小偏心受压区域;针对受压破坏,主要通过减小荷载来控制,并通过计算得到了许用荷载与偏心距的关系。本文研究结果对工程有一定的参考价值。 相似文献
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畸变屈曲作为控制冷弯薄壁卷边槽钢柱承载力的重要模式之一，正逐步受到国内外研究人员的重视。本文针对畸变屈曲的变形特征，通过12根试件在不同连杆布置方式下的轴心受压和偏心受压试验研究，验证在冷弯薄壁卷边槽钢的卷边处设置连杆用以提高其承载力这一方法的有效性．得出了最有效的连杆布置方式。同时，采用有限元软件ABAQUS对试件进行了模拟分析，探讨了初始缺陷、双向偏心等因素的影响。 相似文献
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偏心受压构件中次弯矩对构件受力性能的影响不可忽略。在工程设计中,对次弯矩影响有多种处理方法。在我国通常用增大偏心矩的方法来考虑。本文结合现行规范对次弯矩进行了分析,及在工程中的应用。 相似文献
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在对钢筋混凝土矩形截面单向偏心受压柱的正截面承载力计算时,通常有两种计算方法,对称配筋与非对称配筋,无论哪种计算方法,首先需要初步判别大小偏心类型,再进行后续计算.本文通过算例说明,对于大偏压情况下的非对称配筋,初步判别不能作为最终的偏心构件判别标准,必须在初步判别的基础上合理选择钢筋直径和根数,得到确切的钢筋面积后进... 相似文献
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文章通过对6根陶粒混凝土不等肢L形截面异彤柱在双向偏心受压作用下正截面承载力的试验研究,验证了截面平均应变的平截面假定,试验表明中和轴不垂直于弯矩平面,中和轴位置随荷载作用的增大而变化,并可用截面混凝土受压等效矩形应力图计算极限荷载值. 相似文献
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随着旧路改(扩)建的需要，原有公路桥梁急需帮宽、补强加固利用，依饶公路七里沁河大桥，桥面窄荷载等级低，以不能满足改建后的技术标准要求，鉴于原桥质量状态较好，将其进行帮宽和体外预应力补强加固利用，有很高的经济效益。本桥改造计算中，采用大(小)边梁偏心受压公式法计算主梁荷载横向分布系数，是切实可行的。 相似文献
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构造柱与组合砖砌体柱不同,后者是当砌体受压构件偏心距较大（e〉0．7r）、无筋砌体承受能力不足而柱截面尺寸受其他条件的限制又不能扩展或要求砌体受压构件有一定的延性和变形能力时,在砌体的外表面附以混凝土或抹砂浆面层共同组成受压构件。这种组合砌体构件一般要求在砌体结构设计规范（GBJ——89）中已有规定,而构造柱则是被包围在砌体结构内部的混凝土柱,其目的是同圈梁共同工作。以提高砌体结构的抗震能力。但在施工过程中,往往对构造柱施工质量不能给予高度重视,不同程度地影响抗震能力和结构安全,给大量的住宅工程带来质量隐患,因此。确保构造柱的施工质量是十分必要的。下面就工作经历谈一谈构造柱的通病以及在构造柱施工时如何防止出现质量通病。 相似文献
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Nieves R. Brisaboa Antonio Fariña Gonzalo Navarro José R. Paramá 《Information processing & management》2011
In recent years, new semistatic word-based byte-oriented text compressors, such as Tagged Huffman and those based on Dense Codes, have shown that it is possible to perform fast direct search over compressed text and decompression of arbitrary text passages over collections reduced to around 30–35% of their original size. Much of their success is due to the use of words as source symbols and a byte-oriented target alphabet. This approach broke with traditional statistical compressors, which use characters as source symbols and a bit-oriented target alphabet. 相似文献
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提出了一种用于LTE网络中头标压缩功能的上下文转移方案,可以用来减小无线链路上的报文开销,降低切换时的信令时延,从而提高整个通信网络的效率. 文中对头标压缩的上下文转移过程进行了详细描述,包括信令报文的处理、上下文转移参数的重建以及头标压缩状态的变迁. 通过仿真分析,对方案的有效性进行了验证.该方案适用于语音通信为主的无线通信网络. 相似文献
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[目的]探讨经皮椎体成形术的临床应用。[方法]回顾性分析椎体压缩骨折患者56例80椎接受椎体成形术治疗后的临床疗效。[结果]术后患者疼痛症状明显减轻,术后3 d及1年的VAS评分较术前差异均有统计学意义(P<0.05);椎体高度恢复明显。[结论]经皮椎体成形术治疗椎体压缩骨折简单快捷、安全有效、疗效显著,临床应用前景良好。 相似文献
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Mohamed A. Gadalla 《Journal of The Franklin Institute》2007,344(5):725-740
This paper presents a dynamic model to simulate the adsorption-desorption processes associated with intermittent heat pump systems. This simulation plays an important role in sizing the adsorption systems for various types of applications in the design stage. A mathematical model that is based on the control volume approach was first developed and then discretized using the finite difference implicit scheme. The equations for the conservation of mass, momentum, and energy in the bed were derived for high-pressure and low-pressure segments, including the adsorbate (refrigerant), the adsorbent (Linde 13X), and the vessel wall. A pseudo-homogeneous model for the compression system was adopted. The numerical results that describe the adsorption-desorption history were obtained. It was found that the amount of the refrigerant recovered in the desorption process at the end of the cyclic operation is smaller than the amount adsorbed during the adsorption process. This indicates that the time for the regeneration process should be longer than the time for the adsorption process in order to raise the sieve temperature. In order to compare the simulated results with experimental data, numerical values for the heat transfer coefficients were theoretically evaluated. To assure the stability of the simulated results, the incremental time of system operation is kept equal or less than the value obtained from the minimum stability requirement. The simulated results of the temperature distribution history during system operation are in good agreement with the conducted experimental results, which led to the conclusion that the model can be used as an effective tool during the design stage and for the system development. 相似文献
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Analysis of arithmetic coding for data compression 总被引：1，自引：0，他引：1
Arithmetic coding, in conjunction with a suitable probabilistic model, can provide nearly optimal data compression. In this article we analyze the effect that the model and the particular implementation of arithmetic coding have on the code length obtained. Periodic scaling is often used in arithmetic coding implementations to reduce time and storage requirements, it also introduces a recency effect which can further affect compression. Our main contribution is introducing the concept of weighted entropy and using it to characterize in an elegant way the effect that periodic scaling has on the code length. We explain why and by how much scaling increases the code length for files with a homogeneous distribution of symbols, and we characterize the reduction in code length due to scaling for files exhibiting locality of reference. We also give a rigorous proof that the coding effects of rounding scaled weights, using integer arithmetic, and encoding end-of-file are negligible. 相似文献
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由于DSP芯片的强大存储容量和运算速度,成为了视频图像处理技术的基础,H.264是用于编码表示视频信息的新一代标准,具有更低的码率、更高的图像质量和更强的容错能力。通过利用DSP的超长指令字结构(VL1W)和流水线结构并综合应用其它手段设计优化程序,使H.264编码效率大大提高。系统包括视频采集模块、视频编码模块和视频输出模块。根据TMS320DM642的结构和功能特点对编码算法进行内核优化和T264代码优化以增强其有效性。 相似文献
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基于FPGA的CCSDS图像数据压缩系统的设计 总被引：1，自引：0，他引：1
针对CCSDS图像数据压缩(IDC)标准,提出了一种基于FPGA的CCSDS IDC并行实现方案.该方案包括离散小波变换(DWT)、直流系数量化编码、位平面编码(BPE)、码字拼接等4个模块.位平面编码模块采用了并行扫描、并行编码的快速算法,以提高编码速度.仿真结果表明了本方案的可行性和有效性,处理时间比现有的CCSDS IDC串行编码改进方法减少了13.6%,适用于空间通信的图像数据压缩编码. 相似文献