Quiescent losses

To improve the efficiency of a switching power supply, one must be able to identify and roughly quantify the various losses. Tosses within a switching power supply roughly fall into four categories switching, conduction, quiescent, and resistive losses. These losses usually occur in combination within any lossy component and are treated separately. 

Quiescent losses are associated with all of the functions required to operate the power circuits. That is all of the circuits associated with the controller IC and any feedback circuits elsewhere in the supply. These losses are typically small compared to the other losses within the supply, but can be analyzed to see if any improvement can be made. 

By the use of many commercial abrasive processes, the corrosion resistance of magnesium alloys can be reduced to such an extent that samples of metal that may lie quiescent in salt water for many hours will, after shot blasting, evolve hydrogen vigorously, and the corrosion rate, as measured by loss of weight, will be found to have increased many hundred-fold. The effect in normal atmospheres is naturally much less, yet the activation of the surface is an added hazard and is the opposite of passivation which is essential if later-applied paint finishes are to have proper durability. 

It has been postulated that wood dust carcinoma results from a multistep process Exposure causes loss of cilia and hyperplasia of the goblet cells and initiation of cuboidal cell metaplasia, followed (after a quiescent period) by squamous cell metaplasia. Decades later, cellular aplasia leads to nasal adenocarcinoma. The time between first occupational exposure to wood dust and the development of nasal cavity adenocarcinoma averages 40 years. Other cancers, including lung cancer, Hodgkin disease, multiple myeloma, stomach cancer, and colorectal cancer and lymphosarcoma, have been mentioned in relation to wood... 

The monolayer can be spread initially either from solvent or as a powder, the latter being preferred. Small rafts which allow monolayer material to seep out slowly and replace losses are usually installed at points on the water surface. Oxygen diffuses readily through insoluble monolayers. The oxygen content of the underlying water is somewhat less (80 per cent saturated rather than the normal 90 per cent saturated), since the surface is more quiescent but this has no adverse effect on life beneath the surface. 

Three different isothermal crystallization experiments were performed in this work classical static (i.e., quiescent) crystallization in the DSC apparatus, dynamic crystallization with the apparatus described above, and dynamic-static crystallization. Dynamic isothermal crystallization consisted in completely solidifying cocoa butter under a shear in the Couette apparatus. Comparison of shear effect with results from literature was done using the average shear rate y. This experiment did not allow direct measurement of the solid content in the sample. However, characteristic times of crystallization were estimated. The corresponded visually to the cloud point and to an increase of the cocoa butter temperature 1 t) due to latent heat release. The finish time, was evaluated from the temperature evolution in cocoa butter. At tp the temperature Tit) suddenly increases sharply because of the apparition of a coherent crystalline structure in cocoa butter. This induces a loss of contact with the outer wall and a sharp decrease in the heat extraction. 

Example 1.2 A poorly insulated horizontal pipe (outer diameter d = 0.100m), with a surface temperature = 44 °C, runs through a large room of quiescent air at = 18 °C. The heat loss per length L of the pipe, Q/L has to be determined. The pipe is taken to behave as a grey radiator with emissivity s = 0.87. The walls of the room are treated as black surroundings which are at temperature = a = 18 °C. 

Above relation (1) between cr and y is exact in linear response, where nonlinear contributions in 7 are neglected in the stress. The linear response modulus (to be denoted as g (f)) itself is defined in the quiescent system and describes the small shear-stress fluctuations always present in thermal equilibrium [1, 3]. Often, oscillatory deformations at fixed frequency co are applied and the frequency dependent storage- (G (m)) and loss- (G"((u)) shear moduli are measured in or out of phase, respectively. The former captures elastic while the latter captures dissipative contributions. Both moduli result from Fourier-transformations of the linear response shear modulus g (f), and are thus connected via Kramers-Kronig relations. 

Earthworms are basically aquatic organisms but can withstand severe desiccation and remain in a quiescent state for months. It has been stated that movement and burrowing cannot proceed normally if the water content of the body falls by more than 18%, but they can survive a loss of 70-75% of their normal water content. Because of sensitivity to moisture and temperature earthworm activity is very seasonal. 

A 250 mm square plate heated to a uniform temperature of 323 K is immersed vertically in a quiescent slurry of 20% (volume) Ti02 in water at 293 K. Estimate the rate of heat loss by free convection from the plate when the rheology of the slurry can be adequately described by the power-law model n = 0.28 m = 10 — 0.2(7 — 20) (Pa s") where T is in °C. 

The continuous solution processes are usually carried out between 120-160 C at 400-500 Ib/in pressure. The diluents may be cyclohexane or isooctane. In one-zone reactors the solid catalyst is evenly dispersed throughout the reactor. In the two-zone reactors (specially constructed) the polymerizations are conducted with stirring in the lower zone where the catalysts are present in concentrations of 0.2-0.6% of the diluent. Purified ethylene is fed into the bottom portions of the reactors. The polymers that form are carried with small portions of the catalyst to the top and removed. To compensate for the loss, additional catalysts are added intermittently to the upper quiescent zones. 

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