scholarly journals Noncontact catalysis: Initiation of selective ethylbenzene oxidation by Au cluster-facilitated cyclooctene epoxidation

2020 ◽  
Vol 6 (5) ◽  
pp. eaax6637 ◽  
Author(s):  
Anyang Peng ◽  
Mayfair C. Kung ◽  
Robert R. O. Brydon ◽  
Matthew O. Ross ◽  
Linping Qian ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Catalytic Effect ◽  
Spin Trap ◽  
Direct Interaction ◽  
Combined System ◽  
Ethylbenzene Oxidation ◽  
Au Nanoclusters ◽  
Oxidation Processes ◽  
Parallel Reactions ◽  
Independent Reaction

Traditionally, a catalyst functions by direct interaction with reactants. In a new noncontact catalytic system (NCCS), an intermediate produced by one catalytic reaction serves as an intermediary to enable an independent reaction to proceed. An example is the selective oxidation of ethylbenzene, which could not occur in the presence of either solubilized Au nanoclusters or cyclooctene, but proceeded readily when both were present simultaneously. The Au-initiated selective epoxidation of cyclooctene generated cyclooctenyl peroxy and oxy radicals that served as intermediaries to initiate the ethylbenzene oxidation. This combined system effectively extended the catalytic effect of Au. The reaction mechanism was supported by reaction kinetics and spin trap experiments. NCCS enables parallel reactions to proceed without the constraints of stoichiometric relationships, offering new degrees of freedom in industrial hydrocarbon co-oxidation processes.

Decolorization of Reactive Black 5 using Peroxymonosulfate in Fentonlike Process

2013 ◽  
Vol 16 (2) ◽  
Author(s):  
Gülin Ersöz ◽  
Süheyda Atalay
Keyword(s):  
Advanced Oxidation Processes ◽  
Catalytic Effect ◽  
Industrial Effluents ◽  
Operating Parameters ◽  
Reactive Black 5 ◽  
Process Performance ◽  
Optimum Conditions ◽  
Oxidation Processes ◽  
Wide Availability ◽  
Initial Ph

AbstractOne of the advanced oxidation processes, the Oxone process, was studied to determine its effects on the decolorization of Reactive Black 5 (RB5) in an aqueous solution. Ferrous ion was chosen as the transition metal due to its potential catalytic effect and wide availability in dye containing industrial effluents. The effects of the operating parameters such as Fe(II) and Oxone concentration, initial pH, and temperature on the process performance were investigated. The optimum conditions were determined as: 0.5 mM of Oxone concentration, 0.5 mM of Fe

Pitch and Roll Motion Control of a Floating Wind Turbine With Hybrid Actuation

2014 ◽  
Author(s):  
Kaveh Jalili ◽  
Yaoyu Li ◽  
Mario A. Rotea
Keyword(s):  
Degrees Of Freedom ◽  
Bending Moment ◽  
Offshore Wind ◽  
Load Testing ◽  
Combined System ◽  
Actuation System ◽  
Floating Offshore Wind Turbines ◽  
Standard Design ◽  
Equivalent Load ◽  
Hybrid Actuation

Platform stabilization and load reduction are of great importance for the successful development of floating offshore wind turbines. The increased degrees-of-freedom (DOF) for the relevant dynamics presents the challenge of underactuation. Recently, a tuned-mass damper (TMD) and active vane have been proposed to control the pitch and roll motions of a floating turbine platform. Simulations have indicated that TMD in the fore-aft (FA) direction cannot reduce the damage equivalent load (DEQL) for the side-to-side (SS) bending moment at the tower-base across all the loading conditions. In this study, the TMD in the FA direction is combined with an active vertical vane to reduce both the FA and SS platform motions and DEQLs. We refer to this combined system of actuation as the “hybrid actuation system”. The effectiveness of this hybrid scheme is demonstrated via simulations which are carried out in accordance with the IEC 61400-3 standard design load case 1.2–fatigue load testing.

COMPLEXITY IN HUMAN AND HUMANOID BIOMECHANICS

2008 ◽  
Vol 05 (04) ◽  
pp. 679-698 ◽  
Author(s):  
VLADIMIR IVANCEVIC ◽  
SANJEEV SHARMA
Keyword(s):  
Internal Control ◽  
Degrees Of Freedom ◽  
Neural Control ◽  
Internal State ◽  
Human Motion ◽  
Total System ◽  
Combined System ◽  
Special Cases ◽  
Significant Difference ◽  
Human Hands

We propose the following complexity conjecture: in a combined biomechanical system, where the action of Newtonian laws cannot be neglected, it is the mechanical part that determines the lower limit of complexity of the combined system, commonly defined as the number of mechanical degrees of freedom. The biological part of such a system, being "more intelligent", naturally serves as a "controller" for the "nonintelligent" mechanical "plant". Although, in some special cases, the behavior of the combined system might have a "simple" output, a realistic internal state space analysis shows that the total system complexity represents either the superposition, or a kind of "macroscopic entanglement" of the two partial complexities. Neither "mutual canceling" nor "averaging" of the mechanical degrees of freedom generally occurs in such a biomechanical system. The combined system has both dynamical and control complexities. The "realistic" computational model of such a system also has its own computational complexity. We demonstrate the validity of the above conjecture using the example of the physiologically realistic computer model. We further argue that human motion is the simplest well-defined example of a general human behavior, and discuss issues of simplicity versus predictability/controllability in complex systems. Further, we discuss self-assembly in relation to conditioned training in human/humanoid motion. It is argued that there is a significant difference in the observational resolution of human motion while one is watching "subtle" movements of a human hands playing a piano versus "coarse" movements of a human crowd at a football stadium from an orbital satellite. Techniques such as cellular automata can model the coarse crowd motion, but not the subtle hierarchical neural control of the dynamics of human hands playing a piano. Therefore, we propose the observational resolution as a new measure of biomechanical complexity. Finally, there is a possible route to apparent simplicity in biomechanics, in the form of oscillatory synchronization, both external (kinematical) and internal (control).

scholarly journals Robust Adaptive Impedance Control With Application to a Transfemoral Prosthesis and Test Robot

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Vahid Azimi ◽  
Seyed Abolfazl Fakoorian ◽  
Thang Tien Nguyen ◽  
Dan Simon
Keyword(s):  
Boundary Layer ◽  
Degrees Of Freedom ◽  
Impedance Control ◽  
Lyapunov Stability Theory ◽  
Biomechanical Properties ◽  
Model Parameters ◽  
Parameter Uncertainties ◽  
Combined System ◽  
Control Effort ◽  
Barbalat’S Lemma

This paper presents, compares, and tests two robust model reference adaptive impedance controllers for a three degrees-of-freedom (3DOF) powered prosthesis/test robot. We first present a model for a combined system that includes a test robot and a transfemoral prosthetic leg. We design these two controllers, so the error trajectories of the system converge to a boundary layer and the controllers show robustness to ground reaction forces (GRFs) as nonparametric uncertainties and also handle model parameter uncertainties. We prove the stability of the closed-loop systems for both controllers for the prosthesis/test robot in the case of nonscalar boundary layer trajectories using Lyapunov stability theory and Barbalat's lemma. We design the controllers to imitate the biomechanical properties of able-bodied walking and to provide smooth gait. We finally present simulation results to confirm the efficacy of the controllers for both nominal and off-nominal system model parameters. We achieve good tracking of joint displacements and velocities, and reasonable control and GRF magnitudes for both controllers. We also compare performance of the controllers in terms of tracking, control effort, and parameter estimation for both nominal and off-nominal model parameters.

On the Passive Control of Friction-Induced Instability Due to Mode Coupling

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Alborz Niknam ◽  
Kambiz Farhang
Keyword(s):  
Friction Force ◽  
Parameter Space ◽  
Mode Coupling ◽  
Degrees Of Freedom ◽  
Passive Control ◽  
Original System ◽  
Contact Friction ◽  
Primary System ◽  
Combined System ◽  
Loss Of Contact

This study investigates a passive controller for a coupled two degrees-of-freedom (DOFs) oscillator to suppress friction-induced mode-coupling instability. The primary system is acted upon by a friction force of a moving belt and static coupling of the oscillator provided with an oblique spring. The combined system, original system plus absorber, response is governed by two sets of differential equations to include contact and loss of contact between the mass and the belt. Therefore, the model accounts for two sources of nonlinearity in the system: (1) discontinuity in the friction force and (2) intermittent loss of contact. Friction coefficient and absorber orientation are used to define planar parameter space for stability analysis. For various mass ratios, the parameter space is divided into stable and unstable zones by defining stability boundaries. In general, an absorber expands the stability region and provides a significant reduction in transient response overshoot and settling time. Incorporation of the absorber also prevents mass-belt separation, thereby suppressing the belt-speed-overtake by the primary mass.

scholarly journals Physical, Modular and Articulated Interface for Interactive Molecular Manipulation

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5415
Author(s):  
Bastien Vincke ◽  
Mohamed Anis Ghaoui ◽  
Nicolas Férey ◽  
Xavier Martinez
Keyword(s):  
Degrees Of Freedom ◽  
Direct Interaction ◽  
Rational Drug Design ◽  
Embedded Sensors ◽  
Detailed Knowledge ◽  
Interactive Tools ◽  
Innovative Methodology ◽  
Rational Drug ◽  
Molecular Manipulation ◽  
Interaction Approach

Rational drug design is an approach based on detailed knowledge of molecular interactions and dynamic of bio-molecules. This approach involves designing new digital and interactive tools including classical desktop interaction devices as well as advanced ones such as haptic arms or virtual reality devices. These approaches however struggle to deal with flexibility of bio-molecules by simultaneously steering the numerous degrees of freedom. We propose a new method that follows a direct interaction approach by implementing an innovative methodology benefiting from a physical, modular and articulated molecular interface augmented by wireless embedded sensors. The goal is to create, design and steer its in silico twin virtual model and better interact with dynamic molecular models.

Evaluation of Energy and Power Flow in a Nonlinear Energy Sink Attached to a Linear Primary Oscillator

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Christian E. Silva ◽  
Amin Maghareh ◽  
Hongcheng Tao ◽  
Shirley J. Dyke ◽  
James Gibert
Keyword(s):  
Power Flow ◽  
Degrees Of Freedom ◽  
Nonlinear Energy Sink ◽  
Primary System ◽  
Combined System ◽  
Analytical Treatment ◽  
Different Types ◽  
Energy Sink ◽  
And Performance ◽  
Nonlinear Energy

Abstract The objective of this study is to develop a novel methodology to assess the energy flow between a nonlinear energy sink (NES) and the primary system it is attached to in terms of energy orientation, which is directly related to the sign of the power present on the primary system. To extend the work done in previous studies, which have focused primarily on the analytical treatment, characterization, and performance evaluation of NES as passive nonlinear dampers for structures under different types of excitations, this study incorporates a methodology for determining whether energy is entering or leaving a primary oscillator when interacting with an NES, by means of considering the power flow of the primary oscillator. Several current measures for evaluating the effectiveness of the NES at extracting and dissipating energy irreversibly are considered through numerical simulations of systems with different damping cases of the NES. Each case provides a different dissipation scenario in the combined system, which is subjected to different types of base excitation signals such as impulse and seismic records. The methodology is further validated experimentally using a two degrees-of-freedom system with an NES attached to the second mass. Comparisons of the modeled responses versus the measured responses are provided for several physical damping realization scenarios in the NES.

Efficient Loads Analyses of Shuttle-Payloads Using Dynamic Models With Linear Or Nonlinear Interfaces

1990 ◽  
Vol 112 (3) ◽  
pp. 366-373 ◽  
Author(s):  
P. D. Spanos ◽  
T. T. Cao ◽  
D. A. R. Nelson ◽  
D. A. Hamilton
Keyword(s):  
Dynamic Model ◽  
Dry Friction ◽  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Space Shuttle ◽  
Equations Of Motion ◽  
Combined System ◽  
Time Step ◽  
Upper Stage ◽  
Loads Analysis

A technique is presented for conducting efficient loads analyses of Shuttle-payloads systems with linear or nonlinear attachment interfaces. The technique relies on representing the Space Shuttle and the payloads with physical and modal coordinates. Further, by invoking a standard algorithm of numerical integration of equations of motion, the kinematics of the interface degrees of freedom at a given time are determined without calculating the modes of the combined system involving the Space Shuttle and the payload. If the Shuttle-payloads interface coupling induces a linear dynamic model for the loads analysis, the equations of motion of the Shuttle and the payload are integrated separately step-by-step in time. If the dynamic model is nonlinear, the equations of motion of the Shuttle and the payload are again integrated separately. However, in the latter case an iterative procedure is used within a time step to converge to reliable values of the nonlinear terms of the equations of motion. The usefulness of the proposed technique is demonstrated by conducting a loads analysis for the Shuttle abort landing event with the Inertia Upper Stage (IUS) booster carrying a Tracking and Data Relay Satellite (TDRS) in the payload bay. This combined system has at its interface dry friction and hydraulic nonlinear dampers. For the analysis of this system, the discontinuous signum function used traditionally in modeling dry friction is replaced by an expeditious continuous approximation. Because of its efficiency and versatility, the new technique deserves serious consideration for becoming a standard tool for linear or nonlinear analysis of combined systems, in general, and of Shuttle-payloads systems, in particular.

Construction and Use of the Frequency-Energy Plot for a System With Two Essential Nonlinearities

2011 ◽  
Author(s):  
Sean A. Hubbard ◽  
Alexander F. Vakakis ◽  
Lawrence A. Bergman ◽  
D. Michael McFarland
Keyword(s):  
Degrees Of Freedom ◽  
Normal Modes ◽  
Nonlinear Normal Modes ◽  
Present System ◽  
Combined System ◽  
Strongly Nonlinear ◽  
Energy Transfers ◽  
Strongly Nonlinear System ◽  
Nonlinear Normal ◽  
Energy Plane

We consider the problem of depicting possible periodic motions of a strongly nonlinear system in the frequency-energy plane. The particular case of a 2-degree-of-freedom, linear primary structure coupled to a 2-DOF, nonlinear attachment is examined in detail. While there exist numerical tools for the semiautomatic computation of such frequency-energy plots (FEPs), the presence of multiple essential (nonlinearizable) nonlinearities in the present system introduces new challenges in their application. Furthermore, the multiple degrees of freedom of the nonlinear subsystem allow the existence of complex nonlinear normal modes localized there but exhibiting more complicated resonances than those previously observed in the study of a single-DOF nonlinear attachment. The FEP generated for a laboratory-scale mechanical system is interpreted to explain the transitions and energy transfers that occur in the simulated transient response of the combined system following broadband shock excitation.

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