TEC

About: TEC is a research topic. Over the lifetime, 5119 publications have been published within this topic receiving 84696 citations.

Experimental study on water-cooled thermoelectric cooler for CPU under severe environment

Abstract: In this paper, water-cooled thermoelectric cooler (TEC) for central processing unit (CPU) is developed. Two temperature controls for TEC are proposed and compared to prevent condensation on CPU and save energy. Performances of TEC with the two temperature controls are experimentally investigated under different operating conditions and environmental temperatures. Effects of air velocity and water mass flow rate for the heat sink are investigated under severe environment. Dynamic performance comparisons of three cooling methods, including TEC with and without temperature control and passive water cooling, are investigated under variable operating conditions at severe environment. Experimental results show that temperature of CPU (T cpu ) for SC is lower than that for OC when T cpu is lower than the set temperature. A higher COP can be kept when air velocity and water mass flow rate is 0.8 ms −1 and 0.042 kg s −1 , respectively. The largest temperature variation of T cpu s is lower than 1.5 °C under variable operating conditions at severe environment.

Modeling and Experimentation of New Thermoelectric Cooler–Thermoelectric Generator Module

Abstract: In this work, a modeling and experimental study of a new thermoelectric cooler–thermoelectric generator (TEC-TEG) module is investigated. The studied module is composed of TEC, TEG and total system heatsink, all connected thermally in series. An input voltage (1–5 V) passes through the TEC where the electrons by means of Peltier effect entrain the heat from the upper side of the module to the lower one creating temperature difference; TEG plays the role of a partial heatsink for the TEC by transferring this waste heat to the total system heatsink and converting an amount of this heat into electricity by a phenomenon called Seebeck effect, of the thermoelectric modules. The performance of the TEG as partial heatsink of TEC at different input voltages is demonstrated theoretically using the modeling software COMSOL Multiphysics. Moreover, the experiment validates the simulation result which smooths the path for a new manufacturing thermoelectric cascade model for the cooling and the immediate electric power generation.

Diurnal double maxima patterns in the F region ionosphere: Substorm-related aspects

Abstract: Daytime double maxima (twin peaks or bite-outs) in the ionospheric total electron content (TEC) at middle and lower latitudes are found to be related to substorm signatures shown in both auroral electrojet and ring current variations. Case studies reveal that during substorm onset and recovery phases, the penetration of magnetospheric convection electric fields and their subsequent {open_quotes}overshielding{close_quotes} effects may be the major dynamical sources of these events. A theoretical low-latitude ionospheric model is used to simulate the dynamical effects of electric field disturbances on F region electron density and TEC. It is demonstrated that the diurnal double maxima in TEC can be created by a combined effect of E x B drift and altitude-dependent F region chemical loss. The required zonal electric fields are found to have greater penetration efficiency in the early evening sector and their latitudinal requirements appear to change with local time. The time scales for the modeled penetration and overshielding effects are 2-3 hours. Modeling results also show that considerable structuring in the local time variation of the ionospheric {open_quotes}equatorial anomaly{close_quotes} can occur due to the interplay of convection electric field penetration and overshielding effects. The possible cause of the midday bite-out ionospheric disturbances by themore » meridional winds associated with traveling atmospheric disturbances (TADs) is also addressed in modeling studies, but the specialized nature of the required TADs makes this a less well understood substorm-related mechanism. 64 refs., 14 figs., 3 tabs.« less

TGF-beta differentially modulates epidermal growth factor-mediated increases in leukemia-inhibitory factor, IL-6, IL-1 alpha, and IL-1 beta in human thymic epithelial cells.

Abstract: The regulation of cytokine production by thymic epithelial cells (TEC) in the thymus is under coordinated and temporal control and is important for the development of T cells. Human TEC express TGF-beta R and epidermal growth factor (EGF) receptor, and produce TGF-beta 3 in vitro and in vivo. Furthermore, EGF has been shown to increase IL-1 alpha, IL-1 beta, IL-6 mRNA and protein levels in human TEC. Since EGF has been shown to modulate TGF-beta effector functions, we determined whether TGF-beta can modulate EGF-mediated increases in cytokine gene expression in human TEC. We established that a single TEC expresses both EGF receptor and TGF-beta R. TGF-beta plus EGF synergistically increased leukemia-inhibitory factor (LIF), additively increased IL-6, but had little effect on IL-1 alpha and IL-1 beta mRNA levels. In contrast, TGF-beta alone increased LIF and IL-6, had little effect on IL-1 alpha, and slightly decreased IL-1 beta mRNA levels. The increases in LIF and IL-6 mRNA levels by TGF-beta plus EGF correlate with the increases in LIF and IL-6 concentrations in TEC culture supernatants as detected by ELISA. We also determined the mechanism responsible for the increases in cytokine mRNA levels. TGF-beta plus EGF did not affect transcription of LIF and IL-6 genes; this suggests that the increases in the steady state levels of cytokine mRNA were mediated post-transcriptionally, most likely at the level of mRNA stability. Our data demonstrate that TGF-beta modulates TEC cytokine production. We speculate that TGF-beta produced in situ plays a role in thymocyte development by directly affecting thymocyte differentiation and by indirectly modulating TEC cytokine production.