Research and Application of an Environmental-Friendly Low-Damage and High Salt-Resistance Slick Water Fracturing Fluid System

The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.

Study on precision dicing process of SiC wafer with diamond dicing blades

An innovative method for high-speed micro-dicing of SiC has been proposed using two types of diamond dicing blades,a resin-bonded dicing blade and a metal-bonded dicing blade.The experimental research investigated the radial wear of the dicing blade,the maximum spindle current,the surface morphology of the SiC die,the number of chips longer than 10μm,and the chipped area,which depend on the dicing process parameters such as spindle speed,feed speed,and cutting depth.The chipping fractures in the SiC had obvious brittle fracture characteristics.The performance of the metal-bonded dicing blade was inferior to that of the resin-bonded dicing blade.The cutting depth has the greatest influence on the radial wear of the dicing blade,the maximum spindle current,and the damage to the SiC wafer.The next most important parameter is the feed speed.The parameter with the least influence is the spindle speed.The main factor affecting the dicing quality is blade vibration caused by spindle vibration.The optimal SiC dicing was for a resin-bonded dicing blade with a spindle speed of 20000 rpm,a feed speed of 4 mm/s,and a cutting depth of 0.1 mm.To improve dicing quality and tool performance,spindle vibrations should be reduced.This approach may enable high-speed dicing of SiC wafers with less dicing damage.

Cost-effective post-tensioned bridge pier with internal dissipation

This paper presents the development and testing of a novel internal dissipation connection for the use of post-tensioned rocking columns.The solution is one of the many referring to the dissipative controlled rocking(DCR)bridge design philosophy.The internal dissipaters are carefully designed to be cost-effective and reduce the over-all construction cost.The dissipaters are fully threaded,Grade 300 bars connected to the permanent column and foundation longitudinal reinforcement with threaded couplers.In this research,a DCR column is subjected to subsequent earthquake events,and the dissipaters’strain design limits are chosen such that there is no need for replacing after a significant seismic event.The result is a recommended design strain limit of 1.5%for the dissi-paters that guarantees the structural integrity of the DCR column after a seismic event.Additionally,a cumulated strain of 5%is recommended for the dissipaters before replacement is suggested.The proposed connection de-tailing with replaceable internal dissipaters,combined with post-tensioned high strength bars and well-confined concrete,provided self-centring capabilities(no residual displacement),dissipation capacity and significantly less damage in the bridge column than a traditional reinforced concrete solution.