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Shifts in the position of the intertropical convergence zone (ITCZ) have great importance for weather, climate, and society. The ITCZ shifts have been extensively studied in current and future warmer climate; however, little is known for its migration in the past on geological time scales. Using an ensemble of climate simulations over the past 540 million years, we show that ITCZ migrations are controlled primarily by continental configuration through two competing pathways: hemispheric radiation asymmetry and cross-equatorial ocean heat transport. The hemispheric asymmetry of absorbed solar radiation is produced mainly by land-ocean albedo contrast, which can be predicted using only the landmass distribution. The cross-equatorial ocean heat transport is strongly associated with the hemispheric asymmetry of surface wind stress, which is, in turn, controlled by the hemispheric asymmetry of ocean surface area. These results allow the influence of continental evolution on global ocean-atmosphere circulations to be understood through simple mechanisms that depend primarily on the latitudinal distribution of land.

In electrical and electronic experiments, 380 V voltage level of high-voltage experiments account for a considerable proportion, and the safety of experiments must be taken into account to prevent accidents before they occur. It is an effective and necessary way to install the emergency power-off protection circuit for electrical and electronic experimental device. The design scheme chooses emergency stop button, AC contactor and air switch with leakage protection. Users press the emergency stop switch to energize the electromagnetic coil of AC contactor. The mechanical action produced by the electromagnetic coil drives the contact to be connected, the phase line L1 generates the leakage through resistance grounding, and the leakage protector cuts off the power supply. The actual utilization is safe and stable, and the effect is good. [ABSTRACT FROM AUTHOR]

The global meridional overturning circulation (GMOC) is important for redistributing heat and, thus, determining global climate, but what determines its strength over Earth's history remains unclear. On the basis of two sets of climate simulations for the Paleozoic characterized by a stable GMOC direction, our research reveals that GMOC strength primarily depends on continental configuration while climate variations have a minor impact. In the mid- to high latitudes, the volume of continents largely dictates the speed of westerly winds, which in turn controls upwelling and the strength of the GMOC. At low latitudes, open seaways also play an important role in the strength of the GMOC. An open seaway in one hemisphere allows stronger westward ocean currents, which support higher sea surface heights (SSH) in this hemisphere than that in the other. The meridional SSH gradient drives a stronger cross-equatorial flow in the upper ocean, resulting in a stronger GMOC. This latter finding enriches the current theory for GMOC.

A compact diode-end-pumped actively Q-switched intracavity Raman laser with Tm,Ho:GdVO(4) laser gain medium and BaWO(4) Raman gain crystal is demonstrated for the first time. The Raman threshold is as low as 2.0 W of diode power at 802 nm. The highest average output power of 186 mW at the first Stokes wavelength of 2533 nm is obtained at a pulse repetition rate of 1 kHz, and a pump power of 2.8 W, corresponding to a diode-to-Stokes optical conversion efficiency of 6.6%. The pulsewidth and pulse energy are 7.8 ns and 0.19 mJ, respectively.