An interesting universal modeling tool for rechargeable lithium batteries is presented in this paper. The generic model is based on an equivalent circuit technique commonly used in electrochemical impedance characterization. Therefore, the parameters used in the model can be easily parameterized from the electrochemical impedance derivations, which provide a convenient integration with experimental cell characterizations. Such integration offers the universality in this modeling approach. 相似文献
Sandia National Laboratories has conducted a sequence of studies on the performance of lithium ion and other types of electrochemical cells using inductive models. The objectives of some of these investigations are: (1) to develop procedures to rapidly determine performance degradation rates while these cells undergo life tests; (2) to model cell voltage and capacity in order to simulate cell output under variable load and temperature conditions; (3) to model rechargeable battery degradation under conditions of cyclic charge/discharge, and many others. Among the uses for the models are: (1) to enable efficient predictions of battery life; (2) to characterize system behavior.
Inductive models seek to characterize system behavior using experimentally or analytically obtained data in an efficient and robust framework that does not require phenomenological development. There are certain advantages to this. Among these advantages is the ability to avoid making measurements of hard to determine physical parameters or having to understand cell processes sufficiently to write mathematical functions describing their behavior. We have used artificial neural networks (ANNs) for inductive modeling, along with ancillary mathematical tools to improve their accuracy.
This paper summarizes efforts to use inductive tools for cell and battery modeling. Examples of numerical results are presented. 相似文献
The strain-controlled fatigue behavior of the new nickel-chromium-molybdenum superalloy, HASTELLOY® C-2000® was investigated. Low-cycle fatigue specimens were tested in strain-controlled fatigue conditions under axial strain range control at 24 °C, 204 °C and 427 °C. The results indicated that at total strain ranges below 0.8%, temperature does not significantly influence fatigue life, whereas at high total strain ranges, there is a significant drop in fatigue life at 427 °C. At room temperature and 204 °C, the cyclic stress response was cyclic hardening, followed by cyclic stability, cyclic hardening, or cyclic softening, depending on the total strain range. At 427 °C, only cyclic hardening was observed. Fractographic and metallographic analyses were also conducted. The strain-life and Holloman relation parameters are calculated. A theoretical model that predicts the life of this alloy under the tested conditions using the plastic strain energy method is also presented. The results of the theoretical model are in good agreement with the experimental results. 相似文献
In this letter, a novel type of high-voltage n-channel junction field-effect transistor (JFET) was designed using a conventional n-channel laterally diffused metal-oxide-semiconductor (n-LDMOS) without changing any step in the process. High-voltage JFET can be a start-up device in power factor correction, dc-ac converters, and ac-dc converters for providing a self-powered circuit and minimizing standby power losses without gate control because of its negative threshold voltage. Experimental results show that an n-LDMOS with this JFET structure can achieve a reverse blocking voltage of more than 700 V with very low leakage current. The pinch-off voltage can be designed by changing n-well width to meet the circuit requirement. 相似文献
X-ray diffraction patterns show that most samples of Y1-x PrxBa2Cu4O8 examined in the present study contained a single YBa2 Cu4O8 (1-2-4) superconductive phase for x<0.7.Lattice parameters a and b increased with Pr concentration, suggesting that most of the Pr is trivalent in Y1-x Prx-Ba2Cu4O8. The zero-resistance temperature, T co, decreases monotonically from 80 K at x=0 to 12 K at x=0.65, and superconducting transition widths tend to broaden for x>0. The room-temperature resistivity changes linearly until x=0.7 and increases abruptly at x=-0.75. The critical concentration, xcr, thus was estimated to be 0.7. The effective magnetic moments of Pr in Y 1-x PrxBa2Cu4O8 were 3.63., 3.35, and 3.23, μB for x=0.2, 0.4 and 0.6, respectively. In the R0.8 Pr0.2Ba2Cu4O8 system, the depression of Tc weakly depends on the ionic radius of rare-earth elements. Similarities and differences between Y 1-x PrxBa2Cu4O8 and Y1-xPrx-Ba2Cu3O7-y also were noted and are discussed in this paper. 相似文献
Monoclonal antibodies derived from the actin multigene family are routinely used as an adjunct to morphologic diagnoses of smooth muscle tumors. Northern blot analysis was performed on 60 surgical resections utilizing isoactin-specific cDNAs. A comparison of this analysis to immunohistochemical studies demonstrated that actin-specific monoclonal antibodies represent reliable markers of the smooth muscle lineage. Smooth muscle neoplasms showed a unique pattern of gamma-smooth muscle isoactin gene expression, providing a potentially valuable molecular adjunct to the morphologic diagnosis of uterine smooth muscle tumors. 相似文献
A high-speed and high-sensitivity thermographic-infrared (IR) imaging system has been used for nondestructive evaluation of
specimen-temperature evolutions during high-cycle fatigue experiments. The relationship among the temperature, stress-strain
state, and fatigue behavior is discussed. Both thermodynamics and heat-transfer theories are applied to model and quantify
the observed temperature variations during fatigue. The predicted and measured temperature evolutions and inelastic strains
during fatigue were found to be in good agreement. During fatigue experiments, in-situ observations as well as qualitative and quantitative analyses of Lüders-band evolutions, crack propagation, plastic zones,
and final fracture have been performed by thermography, which can open up wide applications of thermography in detecting the
in-situ heat-related processes, including mechanical damages and phase transformations, of materials and structural components. 相似文献
The fatigue crack growth rate (FCGR) properties of SA508 C1 2a and SA533 Gr A C1 2 pressure vessel steels and the corresponding
automatic submerged are weldments were developed in a high-temperature pressurized water (HPW) environment at 288 °C (550°F)
and 7.2 MPa (1044 psi) at load ratios of 0.02 and 0.50. The HPW enviromment FCGR properties of these pressure vessel steels
and submerged arc weldments were generally conservative, compared with the approrpriate American Society of Mechanical Engineers
(ASME) Section XI water environmental reference curve. The growth rate of fatigue cracks in the base materials, however, was
considerably faster in the HPW environment than in a corresponding 288°C (550°F) base line air environment. The growth rate
of fatigue cracks in the two submerged are weldments was also accelerated in the HPW environment but to a significantly lesser
degree than that demonstrated by the corresponding base materials. In the air environment, fatigue striations were observed,
independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater
environmental effect on crack growth rates displayed by the base materials, as compared with the weldments, was attributed
to a different sulfide composition and morphology. 相似文献