The Development of a High-Performance Distributed Battery Management System for Large Lithium Ion Packs

A high performance battery management system (BMS) for large capacity cells was designed, built, and tested in a cycle of three revisions. The BMS was designed for use in applications where the battery pack configuration is unknown: parallel, series, or any combination. Each of the cells is equipped with its own battery management system to allow a peer-to-peer mesh network to monitor the safety of the cell. The BMS attached to each cell also is equipped with a 25A DC/DC converter to perform active balancing between cells in a string. This converter can transfer charge to (or from) a cell of higher potential and a cell of lower potential at the same time. The balancing circuit has a peak efficiency of 85.3%. The system draws only 53mA while balancing at 25A helping to increase low current performance. The system draws just under 5mA over all while active. Each BMS is equipped with one current sensor, which can measure ±800A with a second ±120A current range. Additionally, the board is equipped with coulomb counting to provide a better understanding of each cell. While this design has many great features, lack of full software support makes many of the subsystems dependent on user interaction to use. As a result, the design is not fully complete. Additionally, last minute design changes on the final revision resulted in detrimental effects to the accuracy of many of the analog circuits including the current sensing features

The Study of the Forward-Voltage to Junction-Temperature Coefficient Degradation in Light-Emitting Diodes

Light-emitting diodes (LEDs) have recently become exceedingly popular in general lighting. As their popularity grows, the demand of more complex and more powerful systems grows as well. While optical characteristics are a crucial component of any lighting product, the main selling point of an LED is their long life and reliability. Unfortunately, the lifetime and reliability of a LED are heavily dependent on the junction temperature of the LED. Thermal management for LEDs has become an important field study for LEDs. Unfortunately, as the LEDs grow smaller and more integrated, it becomes impossible at times to directly measure their junction temperature. When this occurs, the use of the forward-voltage to junction-temperature coefficient, or K-factor, can be used to aid in measuring the junction temperature. Often the K-factor value is quoted as a constant, even while the rest of the LED degrades. This thesis explores the use of the K-factor and attempts to determine if there is a significant change in the K-factor due to degradation. To test this, a custom data acquisition system was built. Two test groups were thermally aged and periodically recalibrated to detect any changes in the K-factor. At the end of the 3000-hour test, one board had failed due to degradation, while the second board did show a statistically significant change in the K-factor; which was slightly more than 10%

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Replacement for the 10 page paper? A pilot project using blogs and wikis for a collaborative EBM assignment in a 3rd year internal medical clerkship

Objective Pilot a group assignment using blogs and wikis to develop evidence-based medicine skills in third year medical students on an internal medicine clerkship. Instead of the clerkship’s previous individual ten-page paper assignment, the students were divided into four groups of sixteen. During the clerkship, students are on geographically dispersed rotations. The earlier ten-page paper had required the students to complete a patient history and physical write-up. With the pilot project, each group was assigned a librarian and a physician faculty mentor. Each student recorded on the blog a clinical scenario and question they encountered. They were encouraged to communicate with the librarian to construct a well formed clinical question. Each student group then came to consensus on which question to pursue and collaborated on a wiki including a list of citations to the best available evidence, a critique of the studies, and implications for the patient

A Gradient-Based Implicit Blend

International audienceWe introduce a new family of binary composition operators that solves four major problems of constructive implicit modeling: suppressing bulges when two shapes merge, avoiding unwanted blending at a distance, ensuring that the resulting shape keeps the topology of the union, and enabling sharp details to be added without being blown up. The key idea is that field functions should not only be combined based on their values, but also on their gradients.We implement this idea through a family of C1 composition operators evaluated on the GPU for efficiency, and illustrate it by applications to constructive modeling and animation

Aberrant Cerebellar Development in Mice Lacking Dual Oxidase Maturation Factors

Background: Thyroid hormone (TH) plays a key role in the developing brain, including the cerebellum. TH deficiency induces organizational changes of the cerebellum, causing cerebellar ataxia. However, the mechanisms causing these abnormalities are poorly understood. Various animal models have been used to study the mechanism. Lacking dual oxidase (DUOX) and its maturation factor (DUOXA) are major inducers of congenital hypothyroidism. Thus, this study examined the organizational changes of the cerebellum using knockout mice of the Duoxa gene (Duoxa?/?). Methods: The morphological, behavioral, and electrophysiological changes were analyzed in wild type (Wt) and Duoxa-deficient (Duoxa?/?) mice from postnatal day (P) 10 to P30. To detect the changes in the expression levels of presynaptic proteins, Western blot analysis was performed. Results: The proliferation and migration of granule cells was delayed after P15 in Duoxa?/? mice. However, these changes disappeared by P25. Although the cerebellar structure of Duoxa?/? mice was not significantly different from that of Wt mice at P25, motor coordination was impaired. It was also found that the amplitude of paired-pulse facilitation at parallel fiber?Purkinje cell synapses decreased in Duoxa?/? mice, particularly at P15. There were no differences between expression levels of presynaptic proteins regulating neurotransmitter release at P25. Conclusions: These results indicate that the anatomical catch-up growth of the cerebellum did not normalize its function because of the disturbance of neuronal circuits by the combined effect of hypothyroidism and functional disruption of the DUOX/DUOXA complex.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140263/1/thy.2015.0034.pd

Impalement Injury of the Urinary Bladder: A Case Report

Impalement injury of the urinary bladder, especially secondary to rectal impalement, is extremely rare. In this case, a 31-year-old man sustained a steel pipe impalement injury through his perirectal region. He presented with gross hematuria, abdominal defense, and a penetrating wound. On the basis of the computed tomography findings and abdominal defense, we suspected a through-and-through bladder perforation from the rectal space to the intraperitoneum. Laparotomy revealed a through-and-through bladder perforation as well as damage to the right ureter, 3 distinct ileal injuries, and rectal anterior, anal, and right seminal vesicle injuries. Surgical repair of each damaged site was undertaken. The prompt diagnosis and surgical repair ensured good postoperative recovery

On the fluctuations of jamming coverage upon random sequential adsorption on homogeneous and heterogeneous media

The fluctuations of the jamming coverage upon Random Sequential Adsorption (RSA) are studied using both analytical and numerical techniques. Our main result shows that these fluctuations (characterized by $\sigma_{\theta_J}$) decay with the lattice size according to the power-law $\sigma_{\theta_J} \propto L^{-1/ \nu}$. The exponent $\nu$ depends on the dimensionality $D$ of the substrate and the fractal dimension of the set where the RSA process actually takes place ($d_f$) according to $\nu = 2 / (2D - d_f)$.This theoretical result is confirmed by means of extensive numerical simulations applied to the RSA of dimers on homogeneous and stochastic fractal substrates. Furthermore, our predictions are in excellent agreement with different previous numerical results. It is also shown that, studying correlated stochastic processes, one can define various fluctuating quantities designed to capture either the underlying physics of individual processes or that of the whole system. So, subtle differences in the definitions may lead to dramatically different physical interpretations of the results. Here, this statement is demonstrated for the case of RSA of dimers on binary alloys.Comment: 20 pages, 8 figure

Chaos in a generalized Lorenz system

A three-component dynamic system with influence of pumping and nonlinear dissipation describing a quantum cavity electrodynamic device is studied. Different dynamical regimes are investigated in terms of divergent trajectories approaches and fractal statistics. It has been shown, that in such a system stable and unstable dissipative structures type of limit cycles can be formed with variation of pumping and nonlinear dissipation rate. Transitions to chaotic regime and the corresponding chaotic attractor are studied in details