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Increasing the power of computer processors and reducing the size of these electronic components has turned the heat transfer issue into a significant challenge in their development. This study investigates the heat transfer enhancement in liquid CPU coolers by applying ultrasonic vibrations. A laboratory setup equipped with a wireless data acquisition system was designed and fabricated. Different configurations of ultrasonic piezoelectric transducers were considered: type 1, where both piezoelectric pieces were mounted on the radiator’s top; type 2, where both piezoelectric pieces were mounted on the radiator’s sides; type 3, where the piezoelectric pieces were mounted on the top and the sides of the radiator at a large distance from each other; and type 4, where the piezoelectric pieces were placed on the top and the sides of the radiator with a small distance between them. The experimental data showed that ultrasonic vibrations improve the cooling performance of computer processors in all four types, especially at lower volumetric airflow rates and higher ultrasonic power levels. Furthermore, a comparison of the different configurations indicated that type 4 and type 1 experienced the highest (20.68%) and the lowest (18.31%) heat transfer improvement due to ultrasonic vibrations.

Using Taguchi's method, the best heat transfer locations for the heating and cooling systems are optimized. To investigate the flow field and heat transfer, the double multi-relaxation time lattice Boltzmann method is used. Sixteen different positions for heating and cooling systems are investigated, the full factorial method for the proposed model considers 44=256experiments, but using the Taguchi method can significantly reduce the number of experiments. In this study, with respect to the number of parameters and levels, the orthogonal array L16of Taguchi's method is proposed which reduces the number of experiments to 16. Various simulations are performed based on the design of the experiments, and the process output changes are measured by a factor called the signal-to-noise ratio. The optimal positions of the heating and cooling systems to maximize and minimize the Nusselt number are found. Also, using analysis of variance (ANOVA), the effective parameters and the percentage of participation of each of them on the Nusselt number are evaluated. In addition, the results show that the height position of the heating system has the greatest effect on the Nusselt number, while the longitudinal position of the cooling system has the least effect.

In this paper the effects of a magnetic field on mixed convection flow in a two‐sided lid‐driven cavity have been analyzed by the lattice Boltzmann method (LBM). The Hartmann number varied from Ha= 0 to 100. The study has been conducted for different Richardson numbers (Ri) from 0.01 to 100 while the direction of the magnetic field was investigated in the x‐direction. Consequences demonstrate that the heat transfer augments with an increment of the Richardson number for different Hartmann numbers for two cases. The heat transfer declines with the growth of the magnetic field for various Richardson numbers for two cases. The difference between the values of heat transfer for the two cases at variant parameters is negligible but the trend of fluid flow for the two cases is multifarious. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (). DOI 10.1002/htj.20402

Purpose To identify clinical characteristics associated with outcomes of treatment for persistent fetal vasculature (PFV) based on a modified classification.Methods In this noncomparative case series, 54 eyes of 47 consecutive patients with PFV managed from 1981 until 1998 at a tertiary eye hospital were reviewed. Pars plicata lensectomy and vitrectomy was performed in 34 eyes and translimbal lensectomy and vitrectomy in five. Fifteen eyes were managed non-surgically. The following outcomes were measured: 1) “Visual improvement”, defined as at least one Zipf's category improvement of best corrected final vision as compared with initial visual acuity, provided that final vision of CSUM (central, steady, unmaintained) equal to 20/100–20/30 was obtained. 2) “Cosmetic acceptability”, defined as the absence of the following: small orbit, externally small appearing eye with microcornea and hypotony, eye deviation more than 35 prism diopters without strabismus surgery and corneal opacity.Results Six eyes were inoperable. In 10 out of 33 operated eyes (30.3%) improvement of vision was obtained including four eyes with an anterior form and six eyes with a combined form of PFV. In univariate analysis, factors such as anterior form of PFV, surgery in the combined form and having a normal retina, had a weak association with a higher chance of visual improvement. In multivariate regression analysis the likelihood of unacceptable cosmetic appearance was higher in females than males (OR = 10.5), and in bilateral cases (OR = 7.9). Offspring of consanguineous marriages had more severe forms of PFV.Conclusions Although visual potential is limited in PFV, some eyes with an anterior or combined form and normal retina achieved improvement of visual acuity after surgery. However, statistically no single factor except sex and bilateral PFV (for cosmetic unacceptability) reliably predicted the results of treatment. Therapy should be individualized based on clinical findings. Genetic studies in offspring of consanguineous marriages with PFV may prove informative.

Purpose To identify the factors influencing anatomical and visual results in cases of rhegmatogenous retinal detachment undergoing primary scleral buckling.Methods A retrospective study of 233 eyes of 226 patients was done. The data were evaluated by univariate analysis and stepwise logistic regression analysis.Results Retinal reattachment was achieved with primary scleral buckling in 197 eyes (84.5%). The extent of retinal detachment, preoperative proliferative vitreoretinopathy (PVR), preoperative visual acuity and relative afferent pupillary defects were identified as influencing anatomical results, by univariate analysis. The predictive roles of extent of retinal detachment (p<0.0001) and preoperative PVR (P=0.0085) were shown to be significant by stepwise logistic regression. As well as the above factors, the patient's age, the duration of symptoms and the status of the macula were predictors of visual results, by univariate analysis. Stepwise logistic regression analysis confirmed the predictive roles of preoperative visual acuity (P < 0.0001) and the extent of retinal detachment (P=0.0089).Conclusions Cases with a larger extent of retinal detachment, more advanced preoperative PVR and poorer preoperative visual acuity have less favorable anatomical and functional results.

Eradication of disease and preservation of function are two of the most important goals in surgery for chronic problems in the ear. Over the past decades, various surgical approaches have attempted to achieve these objectives. Open-cavity mastoidectomy is usually relatively successful in this endeavor; however, it has well-known drawbacks, namely a life-long cavity and poor hearing results in most cases. The closed-cavity technique, on the other hand, has better preservation of function, but traditionally a higher failure rate in eradicating disease and more challenging surgical steps. Intact-bridge mastoidectomy combines (into a one-step, time-tested operation) the benefits of the open-cavity approaches, such as better and safer eradication of disease, with the better functional results seen with closed-cavity techniques.