Single-Layer Symmetrical Full-Port Quasi-Absorptive Filtering Phase Shifter

In this article,a single-layer symmetrical full-port quasi-absorptive filtering phase shifter is presented.The proposed phase shifter is composed of a main quasi-absorptive filtering branch,a reference quasi-absorptive filtering branch,and two delay lines.The proposed phase shifter achieves both phase controlling function and quasi-absorptive filtering function for the first time.Each quasi-absorptive filtering branch can realize the quasi-absorptive filtering function.Meanwhile,the constant phase shift can be obtained by combining the two quasi-absorptive filtering branches and the two delay lines.The design formulas can be derived from the even-and odd-mode network analysis,and then two quasi-absorptive filtering phase shifters can be devised easily and quickly.For verification,a 90°quasi-absorptive filtering phase shifter,which is critical for circularly polarized antenna systems,is simulated,manufactured,and measured.

A Comprehensive Method for the Optimization of Cement Slurry and to Avoid Air Channeling in High Temperature and High-Pressure Conditions

Air channeling in the annulus between the casing and the cement sheath and/or between the cement sheath and formation is the main factor affecting the safe operation of natural gas wells at high temperatures and pressures.Prevention of this problem requires,in general,excellent anti-channeling performances of the cement sheath.Three methods to predict such anti-channeling performances are proposed here,which use the weightless pressure of cement slurry,the permeability of cement stone and the volume expansion rate of cement sheath as input parameters.Guided by this approach,the anti-channeling performances of the cement slurry are evaluated by means of indoor experiments,and the cement slurry is optimized accordingly.The results show that the dangerous transition time of the cement slurry with optimized dosage of admixture is only 76 min,the permeability of cement stone is 0.005 md,the volume shrinkage at final setting is only 0.72%,and the anti-channeling performances are therefore maximized.The effective utilization of the optimized cement slurry in some representative wells(LD10–1-A1 and LD10–1-A2 in LD10–1 gas field)is also discussed.

Enhanced ionic diffusion interface in hierarchical metal-organic framework@layered double hydroxide for high-performance hybrid supercapacitors

Layered double hydroxides(LDHs)with abundant accessible active sites are promising electrode materials for hybrid supercapacitor(HSC)due to their ultrahigh theoretical capacitances.However,the structural agglomeration of LDH leads to poor rate capability and durability.Herein,we construct a diffusion-controlled interface in hierarchical architecture of metal-organic framework(MOF)HKUST-1@cobalt-nickel LDH(denoted as HKUST-1@CoNiLDH)through an in situ etching/electro-deposition strategy.The rapid charge transfer and ionic diffusion in HKUST-1@CoNiLDH deliver a remarkable specific capacity of 297.23 mAh·g^(−1) at 1 A·g^(−1),superior to mostly reported LDH-based electrodes.More importantly,the as-prepared HKUST-1@CoNiLDH//activated carbon HSC exhibit a high energy density of 39.8 Wh·kg^(−1) at a power density of 799.9 W·kg^(−1) with an outstanding capacitance retention of 90%after 5,000 charge–discharge cycles.The in-depth understanding of the ionic diffusion among the MOF/LDH interfaces will greatly promote the further development of designing and synthesizing high performance energy conversion and storage devices.