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Reliability study of phase-change nonvolatile memories 总被引:2,自引:0,他引:2
Pirovano A. Redaelli A. Pellizzer F. Ottogalli F. Tosi M. Ielmini D. Lacaita A.L. Bez R. 《Device and Materials Reliability, IEEE Transactions on》2004,4(3):422-427
A detailed investigation of the reliability aspects in nonvolatile phase-change memories (PCM) is presented, covering the basic aspects related to high density array NVM, i.e., data retention, endurance, program and read disturbs. The data retention capabilities and the endurance characteristics of single PCM cells are analyzed, showing that data can be stored for 10 years at 110/spl deg/C and that a resistance difference of two order of magnitude between the cell states can be maintained for more than 10/sup 11/ programming cycles. The main mechanisms responsible for instabilities just before failure as well as for final device breakdown are also discussed. Finally, the impact of read and program disturbs are clearly assessed, showing with experimental data and simulated results that the crystallization induced during the cell read out and the thermal cross-talk due to adjacent bits programming do not affect the retention capabilities of the PCM cells. 相似文献
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《家电科技》2015,(12)
空调内外机在过程以及售后实际使用中频繁出现电感类元器件出现线圈断问题,导致空调使用寿命变短,一直是困扰着空调生产企业以及电感类器件生产厂家的难题,严重影响产品质量,该问题长期存在没有得到有效解决方案。本文从电感类元器件失效机理、器件内部构造、器件应用环境、器件生产工艺等方面进行全面分析。通过器件失效机理、器件环境应力模拟分析等对电感类器件全方位分析论断,分析结果表明:电感类器件在生产过程中由于绕线过紧、焊接温度过高、焊接时间过长、人工焊接手法不规范等原因难以在实际应用环境中以较高的可靠性工作,最终在过程使用以及售后使用过程中出现线圈断失效。电感类元器件失效实际与器件本身生产工艺设计陷存在较大关联;从器件本身应用环境、器件可靠性设计评估、器件应用环境标准、器件生产工艺全面论证分析整改,从器件本身质量提升着手,进行全面、系统化提升器件质量。 相似文献
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本文用数值模拟方法对一维半透明介质内辐射与导热复合换热过程进行了热力学分析,给出了参与性介质中辐射与导热复合换热过程的无因次熵产公式和熵产数公式,分析了辐射—导热参数、光学厚度、散射反照率、壁面黑度对熵产数的影响。结果表明,在整个系统中,熵产数满足热力学第二定律,从而证明了无因次熵产公式及熵产数公式的正确性。最后从熵产数的角度分析了系统中的功损。 相似文献
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Ostroverkhov V. Ostroverkhova O. Petschek R.G. Singer K.D. Sukhomlinova L. Twieg R.J. 《IEEE journal of selected topics in quantum electronics》2001,7(5):781-792
This paper describes the development and optimization of chiral, nonpolar media with large second-order nonlinear optical responses. We employ molecular engineering, quantum-mechanical sum-over-states theory, and measurements of molecular hyperpolarizability by means of Kleinman-disallowed hyper-Rayleigh scattering in order to understand molecular properties. Then we analyze the appropriate arrangement of the chromophores that produce an optimum axial nonlinear optical medium. Chromophores with large Kleinman disallowed traceless symmetric second-rank tensor hyperpolarizabilities β can be aligned so as to result in large susceptibilities χ(2) in structures that lack polar order. We found that Λ-shaped chromophores with C2v or similar symmetry are good candidates for these materials, as they can exhibit large second-rank components of the hyperpolarizability tensor. A wide variety of techniques can be used to fabricate bulk materials belonging to the chiral nonpolar symmetry groups D∞ and D2. The microscopic chromophore alignment schemes that optimize the nonlinear optical response in such materials are deduced from general symmetry consideration for both molecules and bulk. We also speculate on the possible application of such materials as high-bandwidth spatial light modulators 相似文献
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对付弱小信号的雷达目标,如何提高信噪比(SNR)是信号处理的主要工作,也是成功检测目标的重要保障。本文通过对信号处理系统的仿真,分析信号处理对弱小信号目标回波的信噪比改善以及各环节的信噪比损失情况。 相似文献
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分布式光伏出力具有较大不确定性。为分析其对相变储能电-热耦合系统联合调度的影响,对传统区间预测评价指标进行改进,并利用改进的区间预测模型,提出了一种分布式光伏出力波动范围评估方法。基于现有相变储能电-热联合调度模型,合理计及光伏出力波动性,制定了其电-热联合调度策略。并开展不同出力置信水平下,电-热联合调度策略作用后系统的经济性与风险评估。最后通过仿真算例,分析了光伏出力波动与系统经济性和风险性之间的影响关系,为相变储能系统的实际应用提供了参考借鉴。 相似文献
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The photon distribution, as a function of position, angle, and time, is computed using the analytical cumulant solution of the Boltzmann radiative transfer equation (RTE). A linear forward model for light propagation in turbid media for three-dimensional (3-D) optical tomography is formed based on this solution. The model can be used with time resolved, continuous wave (CW), and frequency-domain measurements in parallel geometries. This cumulant forward model (CFM) is more accurate than that based on the diffusion approximation of RTE. An inverse algorithm that incorporates this CFM is developed, based on a fast 3-D hybrid-dual-Fourier tomographic approach using multiple detectors and multiple sources in parallel geometries. The inverse algorithm can produce a 3-D image of a turbid medium with more than 20 000 voxels in 1-2 min using a personal computer. A 3-D image reconstructed from simulated data is presented. 相似文献
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William J. O'Connor 《International Journal of Numerical Modelling》2002,15(2):195-203
In a companion paper, a transmission line matrix (TLM) scheme was presented for the solution of the 1-D equation of waves in moving media, ytt+αyxt+βyxx=0, describing the superposition of two waves with direction-dependent speeds. The TLM model achieved controlled, direction-dependent wave-speed bias by means of supplementary link lines with notional ‘diodes’. Expressions for wave speed, presented without proof, were verified. Here a proof is presented using a new, time-domain approach. The apparent (direction-dependent) inductance and capacitance as seen by a single wave are first established in a generalized way from the TLM algorithm, from which two wave speeds and impedances are then derived. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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在对某电厂的一台发电机改造后的100%定子接地保护装置进行调试过程中发现,根据原来的改造方案无法满足100%定子接地保护的要求,就原来的改造方案和调试过程中出现的问题进行了讨论分析.找出了出现问题的原因,并根据产生问题的原因对原来的保护方案进行了略微的修改,然后进行了调试,调试结果表明修改后的保护方案解决了原保护方案的问题,并完全满足了100%定子接地保护的要求. 相似文献
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吴杨 《电力系统保护与控制》2008,36(17):92-93
通过对一次保护动作行为分析,发现光差保护和高频纵联保护作为线路主保护这一配置方案下高频保护因延时而"拒动"的现象,进而以南瑞RCS-902A保护为例,对高频纵联保护在故障情况下的动作延时进行了详细的分析研究。建议在有条件的情况下,线路主保护避免采用此类保护配置方案。 相似文献
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吴杨 《电力系统保护与控制》2008,36(17)
通过对一次保护动作行为分析,发现光差保护和高频纵联保护作为线路主保护这一配置方案下高频保护因延时而.拒动"的现象,进而以南瑞RCS-902A保护为例,对高频纵联保护在故障情况下的动作延时进行了详细的分析研究.建议在有条件的情况下,线路主保护避免采用此类保护配置方案. 相似文献
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单相重合闸过程中的零序电流暂态过程分析 总被引:1,自引:0,他引:1
分析了单相重合闸过程中零序电流的暂态过程及其对零序电流保护加速段的影响。理论分析和仿真计算发现暂态零序电流主要有非周期分量物高频分量组成,非周期分量占主导地位。提出了新的零序电流保护加速段判据,该判据无需延时,动作迅速。 相似文献
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在对某电厂的一台发电机改造后的100%定子接地保护装置进行调试过程中发现,根据原来的改造方案无法满足100%定子接地保护的要求,就原来的改造方案和调试过程中出现的问题进行了讨论分析。找出了出现问题的原因,并根据产生问题的原因对原来的保护方案进行了略微的修改,然后进行了调试,调试结果表明修改后的保护方案解决了原保护方案的问题,并完全满足了100%定子接地保护的要求。 相似文献