Abstract: Provided is a pier scour protection method by combinating a downward bivariate normal distribution surface and a granular mixture, wherein the method is used for protecting a pier foundation of a sea-crossing or river-crossing bridge from scouring, and when a depth of a local scour hole around the bottom of a pier or a bridge pile reaches a set depth, a downward bivariate normal distribution surface protection structure is laid, and the granular mixture with a specific thickness is laid in the downward bivariate normal distribution surface protection structure. A downward bivariate normal distribution surface structure for defending and a granular mixture layer for weakening horseshoe-shaped vortexes in a scour hole are organically combined, the bivariate normal distribution surface structure is mainly used for defending the downflow in front of the pier, and the granular mixture layer can weaken the horseshoe-shaped vortexes around the piers.

Abstract: An experimental device and method for measuring a motion probability of nonuniform sediment are provided. The method includes: dyeing sediment of different particle sizes to obtain nonuniform dyed sediment, sticking sediment with the same grades to the bottom of a flume to form a rough plate; soaking the nonuniform dyed sediment, laying the nonuniform dyed sediment on the sediment feeder, transporting the sediment by water with given intensity, and once the flow is stable, starting the sediment feeder to perform a test until the sediment stops moving. Collecting, drying and sieving the sediment in the bedload collector and the suspended load collector, and weighing the dyed sediment of different particle sizes. Computing the incipient probability and the suspension probability respectively by measuring the weight ratios of the sediment of different grades from the two collectors to the initial ones.

Abstract: A stepped self-convection condenser comprising a stepped heat absorbing pipe, a stepped steam pipe, a curved water collecting pipe, a condensed water collecting chamber and a heat insulation shell; the steam pipe is coaxially sleeved outside the heat absorbing pipe, and a pipe diameter satisfies a specific formula; cold water and steam flow in the heat absorbing pipe and the steam pipe, respectively, forming bifacial all-natural convection heat transfer inside and outside; layers of the sleeved pipeline are connected in series in a stepped staggered manner and placed on an inclined flat plate with a given slope; every two layers of stepped sleeved pipeline are connected by a detachable sleeved U-shaped pipe and a curved water collecting pipe; the outlet of the condensed water collecting chamber is provided with an air valve; the stepped sleeved pipeline and the condensed water collecting chamber are arranged in the heat insulation shell.

Abstract: The present disclosure provides a reservoir desilting device having a funnel with a bivariate normal surface, which belongs to the technical field of water conservancy projects. The device includes a sediment inlet funnel and a sediment transport pipeline, where the sediment inlet funnel is located in a sediment accumulation area in a reservoir, the sediment transport pipeline is laid on a river bed of the reservoir, a bottom of the sediment inlet funnel is connected to one end of the sediment transport pipeline, and the other end of the sediment transport pipeline penetrates out of a bottom of a dam; and the sediment transport funnel has a shape of a bivariate normal surface, the sediment transport pipeline has a shape of an inverse hyperbolic geodesic curve, and the sediment transport pipeline is provided with a valve.

Abstract: A method and a system for saline-alkali water treatment by multi-membrane nanofiltration and photothermal conversion are provided. The method includes the following steps: separating Na+ contained water from saline-alkali water by multi-membrane nanofiltration; discharging the obtained Na+ contained water into an evaporation zone, and evaporating in grid-shaped pools step by step by sunlight. A membrane separation method is used with nanomembrane as the core to separate monovalent ion water from high-valent ion water, thus separating Na+ contained water from K+ contained water by NF, and finally extracting fresh water from Na+ contained water by a NF-RO component; meanwhile, a fertilizer preparation method can be used to handle high-valent ion water, K+ contained water and fresh water to obtain a liquid fertilizer or a soil conditioner; a KCl drug extraction method is used to treat K+ contained water in step S1 to obtain a potassium-supplementing drug stock solution.

Abstract: A funnel based on bivariate normal distribution is provided, and belongs to the field of daily tools. The funnel is formed by connecting a funnel body in a shape of a bivariate normal distribution with an outlet tube. The funnel body can be formed by rotating a normal distribution curve around the axis of symmetry z with a positive direction pointing to a deep part of the funnel, towards which the fluid flows. An outlet tube is a conical structure with a wide upper part and a narrow lower part. The surface of the funnel body has arbitrary order smoothness at everywhere. The design is simple and the fluid experiences little resistance when it flows through the inner surface. Thus, the funnel can effectively prevented blockage during the transport of fluid, powder and granules and the transport efficiency is remarkably improved.

Abstract: Provided is a pier scour protection method by combinating a downward bivariate normal distribution surface and a granular mixture, wherein the method is used for protecting a pier foundation of a sea-crossing or river-crossing bridge from scouring, and when a depth of a local scour hole around the bottom of a pier or a bridge pile reaches a set depth, a downward bivariate normal distribution surface protection structure is laid, and the granular mixture with a specific thickness is laid in the downward bivariate normal distribution surface protection structure. A downward bivariate normal distribution surface structure for defending and a granular mixture layer for weakening horseshoe-shaped vortexes in a scour hole are organically combined, the bivariate normal distribution surface structure is mainly used for defending the downflow in front of the pier, and the granular mixture layer can weaken the horseshoe-shaped vortexes around the piers.

Abstract: A funnel based on bivariate normal distribution is provided, and belongs to the field of daily tools. The funnel is formed by connecting a funnel body in a shape of a bivariate normal distribution with an outlet tube. The funnel body can be formed by rotating a normal distribution curve around the axis of symmetry z with a positive direction pointing to a deep part of the funnel, towards which the fluid flows. An outlet tube is a conical structure with a wide upper part and a narrow lower part. The surface of the funnel body has arbitrary order smoothness at everywhere. The design is simple and the fluid experiences little resistance when it flows through the inner surface. Thus, the funnel can effectively prevented blockage during the transport of fluid, powder and granules and the transport efficiency is remarkably improved.