Phase change memory (PCM) cells rely on the orders of magnitude difference in resistivity between the crystalline and amorphous phases to store information. However, the temporal evolution of the resistance of the amo...
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ISBN:
(纸本)9781467373623
Phase change memory (PCM) cells rely on the orders of magnitude difference in resistivity between the crystalline and amorphous phases to store information. However, the temporal evolution of the resistance of the amorphous phase, commonly referred to as resistance drift, is a key challenge for the realization of multi-level PCM. In this article, we present a comprehensive description of the time-temperature dependence of the resistance variation in a PCM cell. Our model consists of a structural relaxation model and an electrical transport model. The structural relaxation model is based on the idea that the atomic configuration of the melt-quenched amorphous phase as a whole collectively relaxes towards a more favorable equilibrium state. Experimental results obtained over a wide range of temperatures and times show remarkable agreement with the proposed model.
In this paper an accurate of railway vehicles random vibration analysis method and engineering application systems is employed to do random vibration analysis, geometric models of electrical control cabinets of compre...
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coded modulation (CM) is the combination of forward error correction (FEC) and multilevel constellations. Coherent optical communication systems result in a four-dimensional (4D) signal space, which naturally leads to...
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Polymer electrolyte membrane (PEM) fuel cell systems convert chemical energy from hydrogen into electrical power via a reaction with oxygen. Fuel cells are highly efficient, nearly noiseless, and locally emission-free...
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ISBN:
(纸本)9781467371605
Polymer electrolyte membrane (PEM) fuel cell systems convert chemical energy from hydrogen into electrical power via a reaction with oxygen. Fuel cells are highly efficient, nearly noiseless, and locally emission-free. However, safe and efficient operation requires special system temperatures, mass flow rates of the reaction gases, and a particular excess ratio and gas pressure on the anode and cathode. All values are current dependent and must fall within specific ranges for both stationary and dynamic loads. This paper deals with modeling fuel cell peripherals and with model predictive control (MPC) of gas pressures. This nonlinear MPC handles all kinds of dynamic load changes, while maximizing power efficiency. All experiments were verified on a test bench with a 4,4kW PEM fuel cell.
Digital audio watermarking is a system of insertion and detection of the key which called watermarking key in host audio to prove the intellectual property right of the audio files. In this paper I proposed an enhance...
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ISBN:
(纸本)9781479984343
Digital audio watermarking is a system of insertion and detection of the key which called watermarking key in host audio to prove the intellectual property right of the audio files. In this paper I proposed an enhanced method for watermark generation and embedding according to input audio clip. The generated key is embedded in audio clip with sampling rate of 44.1 KHz with consideration of properties of perceptual domain of human auditory system. Audio clip sequences particularly uses th direct sequence spread spectrum by utilizing the concept of watermark key. The embedding algorithm creates 128 samples and calculates masking threshold value. The Fast Fourier Transform operates at 128 points at each samples and single bit of key is added. After that 128 point reverse mode of Fast Fourier Transformation is taken to write the audio samples in output sequences. The extraction algorithm reads both original and watermarked audio clips and matches each bits from both input audio samples to determine the differences. If there is difference, it is considered as key bit difference and extracted.
Scene-based Audio uses a sound-field technology called “Higher Order Ambisonics” (HOA) to create holistic descriptions of both live-captured and artistically-created sound scenes that are independent of specific lou...
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ISBN:
(纸本)9781510823389
Scene-based Audio uses a sound-field technology called “Higher Order Ambisonics” (HOA) to create holistic descriptions of both live-captured and artistically-created sound scenes that are independent of specific loudspeaker layouts. For efficient representation, the audio can be carried as a set of PCM channels that contain predominant sounds and ambience in separate tracks. Standard audio bandwidth-compression techniques then can be applied to the PCM channels. This approach is in contrast to conventional channel-based sound representations, in which one signal is used for each loudspeaker of a target reproduction system, with the implication that upmixing or downmixing is required when loudspeaker configurations other than the intended one are used for actual reproduction. This paper examines how, with Scene-based Audio, there can be satisfactory reproduction of immersive sound at bitrates corresponding to the equivalent of just 6 channels, while an alternative sound-field method that exclusively employs audio objects typically involves much higher bitrates.
For thermophysical energy storage with phase change materials (PCMs), the power capacity is often limited by the low PCM thermal conductivity (kappa(PCM)). Though dispersing high-thermal conductivity nanotubes and gra...
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For thermophysical energy storage with phase change materials (PCMs), the power capacity is often limited by the low PCM thermal conductivity (kappa(PCM)). Though dispersing high-thermal conductivity nanotubes and graphene flakes increases kappa(PCM), the enhancement is limited by interface thermal resistance between the nanofillers, among other factors such as detrimental surface scattering of phonons. Here, we demonstrate that embedding continuous ultrathin-graphite foams (UGFs) with volume fractions as low as 0.8-1.2 vol% in a PCM can increase kappa(PCM) by up to 18 times, with negligible change in the PCM melting temperature or mass specific heat of fusion. The increase in kappa(PCM), thermal cycling stability, and applicability to a diverse range of PCMs suggests that UGF composites are a promising route to achieving the high power capacity targets of a number of thermal storage applications, including building and vehicle heating and cooling, solar thermal harvesting, and thermal management of electrochemical energy storage and electronic devices.
In this paper, an electrical equivalent circuit for a proton exchange membrane (PEM) electrolyzer is used to develop a Simulink block diagram. The I- V characteristic for a single PEM electrolyzer cell is modeled unde...
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ISBN:
(纸本)9781479919147
In this paper, an electrical equivalent circuit for a proton exchange membrane (PEM) electrolyzer is used to develop a Simulink block diagram. The I- V characteristic for a single PEM electrolyzer cell is modeled under a steadystate and elaborated using an electrical equivalent circuit. Hydrogen production rates characteristics are developed with respect to the input current and power. It is clearly seen that the electrolytic hydrogen production rate increases with the input current in a linear fashion and the variation of hydrogen production rate with the input electrical power is non-linear (i.e. logarithmic). These characteristics are simulated using the developed Simulink/Matlab model of PEM electrolyzer cell. The parameters of the developed model can also be defined by taking into account temperature and pressure effects.
Robots have been stepping steadily into our daily-life. As humans are likely to exist in daily-life scenarios, "human-aware" becomes an essential point for robot navigation in these scenarios. Existing resea...
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ISBN:
(纸本)9781479967650
Robots have been stepping steadily into our daily-life. As humans are likely to exist in daily-life scenarios, "human-aware" becomes an essential point for robot navigation in these scenarios. Existing research works on human aware robot navigation rarely take potential human reaction into account in the motion planner. In contrast, we propose in this paper the concept of potential human reaction aware motion planner (PHRAMP), i.e. the robot had better take potential human reaction into account in its motion planning. We propose a general methodology coined as the potential cost minimization (PCM) framework for realizing PHRAMPs. We present some theoretical characteristics of this framework and explain its relationship with existing methods. We describe an instantiation of the PCM framework which serves as a concrete example PHRAMP to demonstrate the utility and advantage of the PCM framework.
Phase change memory (PCM) has many advantages over the traditional DRAM technology, hence it becomes a promising candidate for main memory. Multi-level cell (MLC) PCM has the benefits of higher capacity and lower cost...
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ISBN:
(纸本)9781479955763
Phase change memory (PCM) has many advantages over the traditional DRAM technology, hence it becomes a promising candidate for main memory. Multi-level cell (MLC) PCM has the benefits of higher capacity and lower cost-per-bit due to store multiple bits in a single cell. However, MLC PCM employs an iterative write scheme, which is precise, reliable but slow, incurring adverse impact on the system performance. In this work, we analyzed the characteristics of the SET pulse in PCM, and modeled the relationship of the resistance and the SET pulse in MLC. Based on the analysis, we proposed a short SET pulse as an iterative pulse for MLC, so as to accelerate the MLC PCM write operation without the reliability degradation. Experimental results show that the Short-SET write scheme could effectively alleviate the long write problem of MLC PCM and improve the system performanceby 90%. Meanwhile, the write power is reduced by 23%.
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