Over the past few years, the air cooling technology improvements present diminishing returns for microprocessors cooling applications. Presently most of the proposed future cooling technologies (i.e. pumped liquid cooling or vapor compressor refrigeration) may need some fluid moving device and a large remote heat exchanger which requires additional volume. Due to the complexity, reliability issues and space requirements it is preferred to extend the air cooling within the current form factors and using passive devices. This paper will show that optimized thermoelectric modules combined with two-phase (liquid/vapor) passive devices can further improve the cooling capability compared to conventional air cooling technologies at reasonable thermoelectric cooler (TEC) power consumption. Current computational fluid dynamics programs are not yet well equipped to find out the most optimized TEC geometry (for a given COP and given thermal requirements) in a reasonable amount of computation time. Therefore, two modeling steps are proposed: find out the preliminary TEC geometry using an ID analytical program (based on uniform heat flux and a given COP) and use it as an input to CFD programs (i.e. Icepak®) for detailed predictions. Using this model, we confirmed that the conventional TEC technology must use some spreading device to dissipate the CPU heat to the TEC cold side. Different spreading devices are considered: solid metal, heat pipe, vapor chambers and single/two phase pumped cooling. Their individual performance integrated with TEC will be presented. In addition, we propose that the TEC performance to be controlled as a function of instantaneous CPU power consumption, ambient temperature and other parameters. This controller offers extra flexibility which can be used for either noise reduction or TEC power reduction. However, such power cycling of the TEC may affect the TEC reliability. Power cycling accelerated test data (>500,000 accelerated cycles) have been performed together with the life predictions will be presented in the paper.

No abstract

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This study describes an innovative, minimally-invasive technique to evaluate perfusion to the talar dome and body as a predictor of avascular necrosis and structural collapse after an open, talar neck fracture/dislocation. The patient was a 31-year-old female status-post polytraumatic motor vehicle accident, with an open talar neck fracture/dislocation. The patient was managed surgically and the 6-week AP radiograph showed positive "Hawkins sign" to central and medial dome, with questionable sclerosis laterally. Due to concerns of developing avascular necrosis, a novel technique utilizing an intraosseous arteriogram (IOA) of the right talus was performed. IOA revealed brisk perfusion to the central and medial dome, with anterolateral ischemia. The anterolateral talus was decompressed and backfilled with calcaneal autograft. This technique allowed for evaluation of talar dome perfusion along with decompression of the talus via bone biopsy. Radiographic findings, pathology and Magnetic Resonance Imaging were combined to confirm diagnosis. The patient returned to ambulation with significant improvement in function in 8-weeks. Serial radiographic surveillance revealed union across the fracture site without collapse of the talar dome, which was confirmed on the 18-month postoperative CT scan. This case demonstrates evaluation and treatment of talar neck AVN utilizing various imaging modalities, including intra-osseous arteriogram with a unique surgical technique. This innovative practice offers advancement of current treatment methods which could lead to improved time to diagnosis and treatment.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.