Imidazoline-based dissymmetric bis-quaternary ammonium salt (DBA), a type of environmentally friendly surfactant, was compounded with thiourea (TU). The inhibition properties of the compound inhibitor for Q235 steel in a simulated oil field that produced water saturated with CO 2 at high temperature were studied by weight loss measurement, polarization curves, cyclic voltammetry, electrochemical impedance spectroscopy, and observation of surface morphology. Weight loss measurements show that DBA alone has poor inhibition efficiency at high temperature, and TU has a narrow inhibition concentration range. However, DBA and TU together show a synergistic effect, which not only overcomes the short comings when used individually, but also significantly reduces the corrosion rate at reduced dosage. DBA-TU acts as a mixed prohibition inhibitor, and can rapidly form a protective film. The inhibition efficiency decreased slowly with soaking time, which shows it has good substantivity. In conclusion, DBA-TU can be used as high temperature corrosion inhibitor against CO 2 corrosion.Keywords Imidazoline-based dissymmetric bis-quaternary ammonium salts Á Thiourea Á High temperature Á Synergistic effect Á CO 2 corrosion & Jing Zhang

The inhibition effect of imidazoline-based dissymmetric bis-quaternary ammonium salt (DBA) and Thiourea (TU) on Q235 steel in CO 2 -saturated simulated oilfield-produced water was studied by means of the weight-loss method, polarization and electrochemical impedance spectroscopy (EIS). The polarization measurements reveal that the compound inhibitors are anodic-type inhibitors that mainly inhibit the anodic process. EIS results show that the changes in the impedance parameters are due to the formation of a protective layer on the Q235 steel surface by the adsorption of inhibitor molecules. The results of energy dispersive X-ray spectroscopy and scanning electron microscopy confirm the existence of the protective layer. The results also show that adsorption model obeys to the FloryHuggins adsorption isotherm. The synergism parameter suggests that the synergistic effect is obvious at concentrations of 100 and 200 mg L -1 , and there is a cooperative mechanism between the DBA and TU.

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The edge-cloud system has the potential to combine the advantages of heterogeneous devices and truly realize ubiquitous computing. However, for service providers to guarantee the Service-Level-Agreement (SLA) priorities, the complex networked environment brings inherent challenges such as multiresource heterogeneity, resource competition, and networked system dynamics. In this paper, we design a framework for the edgecloud system, namely EdgeMatrix, to maximize the throughput while guaranteeing various SLA priorities. First, EdgeMatrix introduces Networked Multi-agent Actor-Critic (NMAC) algorithm to redefine physical resources as logically isolated resource combinations, i.e., resource cells. Then, we use a clustering algorithm to group the cells with similar characteristics into various sets, i.e., resource channels, for different channels can offer different SLA guarantees. Besides, we design a multi-task mechanism to solve the problem of joint service orchestration and request dispatch (JSORD) among edge-cloud clusters, significantly reducing the runtime than traditional methods. To ensure stability, EdgeMatrix adopts a two-time-scale framework, i.e., coordinating resources and services at the large time scale and dispatching requests at the small time scale. The real trace-based experimental results verify that EdgeMatrix can improve system throughput in complex networked environments, reduce SLA violations, and significantly reduce the runtime than traditional methods.