Effects of Diameter and Surface Coverage Ratio of Admixed Nano-particle on Particle-bed Packing Property

A sliding-mode controller for an automotive selective catalytic reduction system is designed to drive its ammonia surface coverage ratio to the target level. The proposed controller only requires NOx, temperature and air flow sensor measurement installed on most mass production vehicles. Selective catalytic reduction systems have been widely equipped on diesel-powered ground vehicles to remove excessive NOx emissions. The tradeoff between NOx removal efficiency and ammonia slip poses a control challenge on regulating the ammonia surface coverage ratio to a proper level in the presence of disturbance. In this study, a sliding-mode controller is designed with explicit consideration of measurement noise and actuator saturation. The finite time convergence of tracking error is proved by a Lyapunov approach. For implementation purpose, an observer of ammonia surface coverage ratio and ammonia slip is also designed to provide states feedback and fault diagnostic information. The closed-loop controller performance is evaluated under an urban driving scenario based on an experimentally validated model. Results demonstrate the robust tracking performance and estimation accuracy against bounded uncertainties. The overall NOx efficiency is maintained with an acceptable ammonia slip level during the transient test cycle FTP75.

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Analysis of Radical Reaction on Growing Surface During Si Epitaxy by Photo-Cvd

MRS Proceedings ◽

10.1557/proc-507-423 ◽

1998 ◽

Vol 507 ◽

Author(s):

Katsuya Abe ◽

Tatsuro Watahiki ◽

Akira Yamada ◽

Makoto Konagai

Keyword(s):

Gas Phase ◽

Surface Reaction ◽

Surface Coverage ◽

Radical Reaction ◽

Reaction Model ◽

Film Structure ◽

Coverage Ratio ◽

Reaction Models ◽

Si Epitaxy ◽

Surface Reaction Model

ABSTRACTThe growth mechanism of Si film at low temperature on Si(100) by photo-CVD was theoretically analyzed by using reaction models both in the gas phase and on the growing surface. We introduced three surface reactions; the growth of Si from SiH3 radicals, the dangling bond termination by atomic hydrogen and the abstraction of bonding hydrogen by SiH3 radicals. We assumed that the film structure is determined by the hydrogen surface coverage ratio “ø” and the parameters of the surface reaction model were determined from the experimental results. The theoretical analysis explained well the experimental data on the growth rate.

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Diesel Engine Selective Catalytic Reduction (SCR) Ammonia Surface Coverage Control Using a Computationally-Efficient Model Predictive Control Assisted Method

ASME 2009 Dynamic Systems and Control Conference, Volume 1 ◽

10.1115/dscc2009-2501 ◽

2009 ◽

Cited By ~ 20

Author(s):

Ming Feng Hsieh ◽

Junmin Wang

Keyword(s):

Diesel Engine ◽

Model Predictive Control ◽

Selective Catalytic Reduction ◽

Predictive Control ◽

Surface Coverage ◽

Catalytic Reduction ◽

Computationally Efficient ◽

Coverage Ratio ◽

Control Objective ◽

Control Authority

This paper presents a diesel engine selective catalytic reduction (SCR) control design based on a novel model predictive control (MPC)-assisted approach, which utilizes the advantages of MPC while keeping the computation demand under an acceptable level. The SCR control problem is featured by the challenges of time delay, significant time-varying characteristics, and limited control authority. Based on the understanding of the SCR reactions, the NH3 surface coverage ratio was selected as the control objective. The proposed MPC-assisted method was compared with conventional controllers such as PID and linear MPC (LMPC). Simulation results exhibited that the MPC-assisted approach can achieve a SCR ammonia surface coverage ratio control with much smaller root mean square error compared to these of other controllers while maintaining a manageable computational demand, and in turn better control of tailpipe NOx and ammonia emissions.

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Effect of solid surface charge on the binding behaviour of a metal-binding peptide

Journal of The Royal Society Interface ◽

10.1098/rsif.2012.0060 ◽

2012 ◽

Vol 9 (75) ◽

pp. 2688-2695 ◽

Cited By ~ 9

Author(s):

Senem Donatan ◽

Mehmet Sarikaya ◽

Candan Tamerler ◽

Mustafa Urgen

Keyword(s):

Surface Charge ◽

Solid Surface ◽

Surface Coverage ◽

Building Blocks ◽

Tuning Parameter ◽

Binding Peptide ◽

Binding Characteristics ◽

Coverage Ratio ◽

Intrinsically Disordered ◽

Hydration State

Over the last decade, solid-binding peptides have been increasingly used as molecular building blocks coupling bio- and nanotechnology. Despite considerable research being invested in this field, the effects of many surface-related parameters that define the binding of peptide to solids are still unknown. In the quest to control biological molecules at solid interfaces and, thereby, tailoring the binding characteristics of the peptides, the use of surface charge of the solid surface may probably play an important role, which then can be used as a potential tuning parameter of peptide adsorption. Here, we report quantitative investigation on the viscoelastic properties and binding kinetics of an engineered gold-binding peptide, 3RGBP 1, adsorbed onto the gold surface at different surface charge densities. The experiments were performed in aqueous solutions using an electrochemical dissipative quartz crystal microbalance system. Hydrodynamic mass, hydration state and surface coverage of the adsorbed peptide films were determined as a function of surface charge density of the gold metal substrate. Under each charged condition, binding of 3rGBP 1 displayed quantitative differences in terms of adsorbed peptide amount, surface coverage ratio and hydration state. Based on the intrinsically disordered structure of the peptide, we propose a possible mechanism for binding of the peptide that can be used for tuning surface adsorption in further studies. Controlled alteration of peptide binding on solid surfaces, as shown here, may provide novel methods for surface functionalization used for bioenabled processing and fabrication of future micro- and nanodevices.

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Backstepping Based Nonlinear Ammonia Surface Coverage Ratio Control for Diesel Engine Selective Catalytic Reduction Systems

ASME 2009 Dynamic Systems and Control Conference, Volume 1 ◽

10.1115/dscc2009-2567 ◽

2009 ◽

Cited By ~ 10

Author(s):

Ming Feng Hsieh ◽

Junmin Wang

Keyword(s):

Diesel Engine ◽

System Dynamics ◽

Selective Catalytic Reduction ◽

Surface Coverage ◽

Catalytic Reduction ◽

Control Law ◽

Ammonia Emissions ◽

Coverage Ratio ◽

Cycle Simulation ◽

Scr System

This paper presents an ammonia surface coverage ratio control approach based on the backstepping concept for diesel engine selective catalytic reduction (SCR) systems. SCR models with multiple cells connected in cascade provide more accurate representations of the actual SCR system dynamics by considering the spatial distribution. Control of SCR system ammonia coverage ratio is critically important and effective in terms of ensuring low tailpipe NOx and ammonia emissions. However, such a task is also very challenging primarily due to the nonlinearities of the SCR dynamics and limited ammonia injection control authority. Grounded in the understanding of the SCR nonlinear dynamic characteristics, a backstepping-based nonlinear control law is then proposed to regulate the ammonia surface coverage ratio of the last SCR cell in order to tightly control the tailpipe NOx and ammonia emissions. Lyapunov-based analyses show the stability of the designed control law. FTP75 test cycle simulation results based on a full-vehicle (including engine, chassis, and aftertreatment systems) model illustrated that, compared with a conventional PID controller, the nonlinear backstepping control law can more appropriately handle the SCR system dynamics and exhibits superior ammonia coverage ratio control capability.

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