Charging fast-charge algorithms

Plimpton S (1995) Fast parallel algorithms for short-range molecular-dynamics. J Comput Phys 117 1-19 Rafii-Tabar H (2000) Modeling the nano-scale phenomena in condensed matter physics via computer-based numerical simulations. Phys Reports-Rev Section Phys Lett 325 240-310 Rescigno TN, Baertschy M, Issacs WA, and McCurdy CW (1999) Collisional breakup in a quantum system of three charged particles. Science 286 2474-2479... 

In practice, the implementation of a pulse-charge algorithm for lithium-ion batteries is more complex. There are two problems with square wave pulses. First, they are not actually square. There is a finite rise-time (slew rate) and decay upon pulse termination. The rise is often accompanied by an overshoot, which further complicates the waveform. Second, high slew rates will produce electronic noise that generally interferes with most electronic equipment and thus will probable not pass qualification tests by regulatory agencies. The answer is to use finite, but fast slewing rates that (1) approximates an instantaneous flux, (2) has minimal overshoot, and (3) does not cause unacceptable amounts of electronic noise. 

Charge Distribution, Inductive and Resonance Effects. Until now, the discussion has been concerned with models based on additivity schemes and their modifications. However, we have also explored other types of models that can be put into algorithms that are fast, albeit less convenient for pencil and paper application. 

Nowadays computers are so absurdly fast that the phase problem can be solved by recursive computation the newly proposed charge-flipping algorithm [14] performs in absence of any information on the target crystal structure not even the molecular composition or the crystal symmetry is needed. The procedure starts with... 

There are nonzero chances that the charge flipping algorithm may make direct methods obsolete. Performing as it is, the algorithm is obscure in its fundamentals. No equations, formulas, or proofs are proposed or derived. In the authors own words [14] we admit our own lack of understanding of it beyond the level of intuition. This is a patent case in which the human brain is almost made superfluous by fast computing. Indeed, this facet of scientific activity has few precedents. 

As an alternative to ab initio methods, the semi-empirical quantum-chemical methods are fast and applicable for the calculation of molecular descriptors of long series of structurally complex and large molecules. Most of these methods have been developed within the mathematical framework of the molecular orbital theory (SCF MO), but use a number of simplifications and approximations in the computational procedure that reduce dramatically the computer time [6]. The most popular semi-empirical methods are Austin Model 1 (AMI) [7] and Parametric Model 3 (PM3) [8]. The results produced by different semi-empirical methods are generally not comparable, but they often do reproduce similar trends. For example, the electronic net charges calculated by the AMI, MNDO (modified neglect of diatomic overlap), and INDO (intermediate neglect of diatomic overlap) methods were found to be quite different in their absolute values, but were consistent in their trends. Intermediate between the ab initio and semi-empirical methods in terms of the demand in computational resources are algorithms based on density functional theory (DFT) [9]. 

Clearly, Cl may not be a universal algorithm, but it would be interesting to see what cycle-lives could be achieved with this procedure on thicker-plate VRLA batteries, where the oxygen cycle is not as active as in the Optima and Genesis products. It should be noted that each product may require a unique approach, as design dictates maximum current levels and recharge times in VRLA products. This has been demonstrated in the Cominco ALABC work on fast charging of Optima (thin-plate) and Delphi (thick-plate) batteries [61]. 

Zhang, Z. and Marshall, A. G. A universal algorithm for fast and automated charge state deconvolution of electrospray mass-to-charge ratio spectra. /. Am. Soc. Mass Spectrom., 9, 225, 1998. 

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