Dynamic Flow Control Strategies of Vehicle SCR Urea Dosing System

Selective Catalyst Reduction（SCR）Urea Dosing System（UDS）directly affects the system accuracy and the dynamic response performance of a vehicle.However,the UDS dynamic response is hard to keep up with the changes of the engine＇s operating conditions.That will lead to low NO_χconversion efficiency or NH_3 slip.In order to optimize the injection accuracy and the response speed of the UDS in dynamic conditions,an advanced control strategy based on an air-assisted volumetric UDS is presented.It covers the methods of flow compensation and switching working conditions.The strategy is authenticated on an UDS and tested in different dynamic conditions.The result shows that the control strategy discussed results in higher dynamic accuracy and faster dynamic response speed of UDS.The inject deviation range is improved from being between-8%and 10%to-4%and 2%and became more stable than before,and the dynamic response time was shortened from 200 ms to 150 ms.The ETC cycle result shows that after using the new strategy the NH_3 emission is reduced by 60%,and the NO_χemission remains almost unchanged.The trade-off between NO_χconversion efficiency and NH_3 slip is mitigated.The studied flow compensation and switching working conditions can improve the dynamic performance of the UDS significantly and make the UDS dynamic response keep up with the changes of the engine＇s operating conditions quickly.

Fuzzy Based Auto-coagulation Control Through Photometric Dispersion Analyzer

The main role of water treatment plants is to supply high-quality safe drinking water. Coagulation is one of the most important stages of surface water treatment. The photometric dispersion analyzer(PDA) is a new optical method for flocculation monitoring, and is feasible to realize coagulation feedback control. The on line modification of the coagulation control system' s set point( or optimum dosing coagulant) has influenced the application of this technology in water treatment plant for a long time. A fuzzy control system incorporating the photometric dispersion analyzer was utilized in this coagulation control system. Proposed is a fuzzy logic inference control system by using Takagi and Sugeno' s fuzzy if-then rule for the self-correction of set point on line. Programmed is the dosing rate fuzzy control system in SIEMENS small-scale programmable logic controller. A 400 L/min middle-scale water treatment plant was utilized to simulate the reaction. With the changes of raw water quality, the set point was modified correctly in time, as well as coagulant dosing rate, and residual turbility before filtration was eligible and stable. Results show that this fuzzy inference and control system performs well on the coagulation control system through PDA.

A Randomized Controlled Trial of Adjunctive Bunchang Naoxintong Capsule (步长脑心通胶囊) Versus Maintenance Dose Clopidogrel in Patients with CYP2C19*2 Polymorphism

Objective：To determine the impact of adjunctive Buchang Naoxintong Capsule（步心脑心通胶囊,NXT） on dual antiplatelet therapy in patients with cytochrome P450 2C19＊2（CYP2C19＊2） polymorphism undergoing percutaneous coronary intervention（PCI）.Methods：Ninety patients with CYP2C19＊2 polymorphism were enrolled,and their genotypes were confirmed by polymerase chain reaction（PCR）.The patients were randomly assigned to receive either adjunctive NXT（triple group,45 cases） or dual antiplatelet therapy（dual group,45 cases） using a computer-generated randomization sequence and sealed envelopes.Platelet function was assessed at baseline and 7 days after treatment with conventional aggregometry.Subsequent major adverse cardiovascular events（MACE,including sudden cardiac arrest and acute coronary syndrome） were recorded during a 12-month followup.Results：Baseline platelet function measurements were similar in both groups.After 7 days,percent inhibitions of maximum platelet aggregation and late platelet aggregation were significantly greater in the triple versus dual group（42.3%±16.0%vs.20.8%±15.2%,P〈0.01,and 54.7%±18.3%vs.21.5%±29.2%,P〈0.01,respectively）.During the 12-month follow-up,the rate of subsequent MACE（6/45） was significantly lower in the triple group compared with the dual group（14/45;P〈0.05）.Conclusion：Adjunctive NXT to maintenance dose clopidogrel（75 g） could enhance the antiplatelet effect and decrease subsequent MACE in patients with the CYP2C19＇2polymorphism undergoing PCI.