Experimental Study on Voltage Sag Tolerance of LED Electronic Display

Widely used LED electronic displays have high requirements for power quality. Because of the status quo of LED technology update and the lack of related experimental work, this paper first analyzes the hardware composition of LED electronic display and switching power supply module. In addition, the paper points out that the transient tolerance of LED screens is mainly determined by switching power supply modules. Then, a test platform was built, and a certain type of LED screen was selected to investigate the influence of voltage temporary drop value and duration, phase jump, and initial Angle of temporary drop on the tolerance of LED electronic display. It provides data support for evaluating and managing the effects of voltage sags on LED electronic displays and the design of power supply schemes.

The effect of mass ratio and tether length on the flow around a tethered cylinder

A tethered cylinder may be considered an extension of the widely studied problem of a hydro-elastically mounted cylinder. Here we numerically investigate the flow past a positively buoyant tethered cylinder for a range of mass ratios and tether length ratios at a Reynolds numberRe= 200. The results are found to be qualitatively similar to related experimental work performed at significantly higher Reynolds numbers. Two important findings are related in this paper. First, we find that the action of the tethered cylinder oscillating at an angle to the flow induces a mean lift coefficient. Second, a critical mass ratio (m*crit) is found below which large-amplitude oscillations are noted, similar to that previously reported for the case of a hydro-elastically mounted cylinder. For short tether lengths, (m*crit) is significantly greater than that found for a hydro-elastically mounted cylinder. As the tether length increases, the (m*crit) decreases and asymptotes to that of a hydro-elastically mounted cylinder as the tether length approaches infinity.

The Significance of Computational Modelling in Murine Cardiac Ventricular Cells

Five decades of histological, electrophysiological, pharmacological and biochemical investigations exist, but relatively little is known regarding the ionic mechanisms underlying the action potential variations in the ventricle associated with healthy and disease conditions. The computational modelling in murine ventricular myocytes can complement our knowledge of the experimental data and provide us with more quantitative descriptions in understanding different conditions related to normal and disease conditions. This paper initially reviews the theoretical modelling for cardiac ventricular action potentials of various species and the related experimental work. It then focuses on the progress of computational modelling of cardiac ventricular cells for normal, diabetic and spontaneously hypertensive rats. Also presented is the recent modelling efforts of the action potential in mouse ventricular cells. The computational insights gained into the ionic mechanisms in rodents will enhance our understanding of the heart and provide us with new knowledge for future studies to treat cardiac diseases in children and adults.

Impact of Hydrogen Overpressure on Spent Fuel Alteration Behavior in Salt Brine During a Three-Year Long Corrosion Test

The corrosion of the Fe-based spent fuel containing canister produces large amounts of hydrogen, which dominate the composition of the gas phase. To quantify to what extent the hydrogen over- pressure may counteract radiolysis enhanced matrix dissolution, related experimental work has been performed. High burnup spent fuel was corroded in 5 M NaCl solution in different tests: (1) Fe ab-sence (<0.16 bar H2 overpressure), (2) Fe presence (2.8 bar H2 overpressure), (3) Fe absence, external applied H2 overpressure of 3.2 bar. In the absence of Fe, after the application of H2 overpressure the UO2 matrix dissolution rate decreased by a factor of about 10. The concentrations of U, Np, Tc in so- lution were found to be decreasing at least two orders, and ranging within the same level as in the presence of Fe powder. However, Pu and Am concentrations were less affected, due to the absence of Fe powder and the associated high sorption capacity for these radioelements.

The dielectric breakdown of low density gases. II. Experiments on mercury vapour

It was shown in the first paper of this series that a pre-breakdown current growth equation could be developed for low pressure gases using modern computer techniques, but that a theory of breakdown presented there could not be proved conclusively because of a lack of experimental data. This paper reviews previous related experimental work on the dielectric properties of mercury vapour and describes the development of the experimental techniques necessary to obtain this data. Results of pre-breakdown current measurements are given at ( E / N ) values, an order of magnitude higher than previously reported. These allow the computation of electron multiplication by electron collision in a gap as well as secondary emission coefficients by positive ion bombardment of the cathode. It is shown that the experimental results for mercury vapour confirm the theory developed in the first paper.

A MODEL OF GROWTH AND GROWTH CONTROL IN MATHEMATICAL TERMS

A practicable model of the growth process, which gives better definition to the problem of growth and growth regulation and greater precision to related experimental work than do earlier models, is developed on the basis of the following assumptions: "Growth" is the net balance of mass produced and retained over mass destroyed and otherwise lost, implying continual metabolic degradation and replacement. Terminal size represents stationary equilibrium between incremental and decremental components. The mass of an organic system consists of two functionally different components,—generative and differentiated. Generative mass increases by the catalytic action of key compounds ("templates") characteristic of each cell type. Each cell also produces specific freely diffusible compounds antagonistic to these templates ("antitemplates"). Growth regulation occurs automatically by a negative "feedback" in which increasing numbers of antitemplates progressively block the corresponding templates. Differential equations expressing these interrelationships are formulated, integrated, and the solutions evaluated for the case of chick growth. These specific solutions lead to descriptions of the normal growth of a biological system which are in good agreement with known facts, and to predictions of the course of automatic growth regulations after experimental or pathological disturbances which reproduce adequately biological observations in this domain.