A Novel Approach for Modeling the Steady-State VSC-Based Multiline FACTS Controllers and Their Operational Constraints

Bi-ventricular (Bi-V) function in primary pulmonary hypertension (PPH) or PH secondary to left heart failure (SPH) remains difficult to characterize. As a measure of ventricular efficiency, ventriculo-arterial coupling (VAC) is calculated as the ratio of effective arterial elastance (Ea) to end-systolic elastance (Ees). No measure currently assesses ventriculo-ventricular coupling (VVC). Therefore, we developed a novel catheter-based approach to quantify Bi-V function using pressure-volume loop (PVL) analysis and hypothesized that Bi-V VAC ratios, defined as the VVC index (VVCI), may discriminate PPH and SPH. Methods: Adult male mice (n=6/group) underwent constriction of the pulmonary artery (PAC) or thoracic aorta (TAC) to model PPH and SPH respectively. Sham-operated animals underwent a left thoracotomy. Closed chest simultaneous Bi-V catheterization was performed after 7 days in PPH and 10 weeks in SPH. Conductance catheters were used for right and left ventricular PVL analysis via the right external jugular vein and right common carotid artery under steady-state conditions and with variable preload. Results: Steady-state Bi-V PVL and changes in VAC ratios and the VVCI are shown below. In sham mice VAC ratios and the VVCI reflect optimal ventricular efficiency. In PPH, the VVCI is significantly increased, while in SPH, the VVCI is significantly decreased compared to controls. Conclusion: These results identify a novel method to quantify Bi-V function in mice and further show that the VVCI can distinguish PPH and SPH. These findings have important implications for examining cardiac function in preclinical and clinical studies of left- and right-sided heart failure.

Download Full-text

A novel approach to distinguish between enzyme mechanisms: quasi-steady-state kinetic analysis of the prostaglandin H synthase peroxidase reaction

Biochemical Journal ◽

10.1042/bj20030043 ◽

2003 ◽

Vol 372 (3) ◽

pp. 713-724 ◽

Cited By ~ 12

Author(s):

Peter V. VRZHESHCH ◽

Elena A. BATANOVA ◽

Alevtina T. MEVKH ◽

Sergei D. VARFOLOMEEV ◽

Irina G. GAZARYAN ◽

...

Keyword(s):

Experimental Data ◽

Steady State ◽

Catalytic Cycle ◽

Prostaglandin H Synthase ◽

Compound I ◽

Novel Approach ◽

Steady State Kinetic ◽

Enzyme Intermediates ◽

Prostaglandin H ◽

State Kinetic

A method of analysis for steady-state kinetic data has been developed that allows relationships between key partial reactions in the catalytic cycle of a functioning enzyme to be determined. The novel approach is based on a concept of scalar and vector ‘kinetic connectivities’ between enzyme intermediates in an arbitrary enzyme mechanism. The criterion for the agreement between experimental data and a proposed kinetic model is formulated as the kinetic connectivity of intermediate forms of the enzyme. This concept has advantages over conventional approaches and is better able to describe the complex kinetic behaviour of prostaglandin H synthase (PGHS) when catalysing the oxidation of adrenaline by H2O2. To interpret the experimental data for PGHS, a generalized model for multi-substrate enzyme reactions was developed with provision for irreversible enzyme inactivation. This model showed that two enzyme intermediates must undergo inactivation during the catalytic cycle. These forms are proposed to be PGHS compound I and a compound I–adrenaline complex.

Download Full-text

Dynamic Versus Steady-State Modeling of FACTS Controllers in Transmission Congestion

2006 IEEE PES Power Systems Conference and Exposition ◽

10.1109/psce.2006.296261 ◽

2006 ◽

Cited By ~ 1

Author(s):

Claudio Canizares ◽

Sameh Kodsi

Keyword(s):

Steady State ◽

Transmission Congestion ◽

Facts Controllers

Download Full-text

A Hydraulic Rotary Switched-Inertance Servo-Transformer

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.3152664 ◽

1988 ◽

Vol 110 (2) ◽

pp. 144-150 ◽

Cited By ~ 23

Author(s):

F. T. Brown ◽

S. C. Tentarelli ◽

S. Ramachandran

Keyword(s):

Steady State ◽

High Frequency ◽

Pulse Width ◽

Pulse Width Modulation ◽

Complete Solution ◽

Partial Solution ◽

State Theory ◽

Novel Approach ◽

Flow Through ◽

Theory And Experiments

Switched-reactance hydraulics represents a radically novel approach to the control of fluid power, since the proportional metering of flow through adjustable orifices is eliminated, and the inertive properties of the fluid substituted. Potential advantages in bandwidth, linearity, and efficiency have been indicated. This paper presents the first steady-state theory and experiments with a rotary fluid switch, which accomplishes the needed pulse-width modulation at a desirably high frequency. Cavitation problems are observed, means of their partial solution are implemented, and means of a more complete solution are indicated.

Download Full-text

Steady-State Wave Propagation in Multilayered Viscoelastic Media Excited by a Moving Dynamic Distributed Load

Journal of Applied Mechanics ◽

10.1115/1.3086586 ◽

2009 ◽

Vol 76 (4) ◽

Cited By ~ 5

Author(s):

Lu Sun ◽

Wenjun Gu ◽

Feiquan Luo

Keyword(s):

Steady State ◽

Moving Load ◽

Impulse Response Function ◽

Constitutive Models ◽

Numerical Algorithms ◽

Point Load ◽

Fast Evaluation ◽

Viscoelastic Media ◽

Distributed Load ◽

Novel Approach

An analytical solution of steady-state dynamic response of a multilayered viscoelastic medium to a moving distributed load is obtained using a novel approach that combines transfer matrix method with Sun’s convolution representation integrated over impulse response function of the layered medium. The layered media under consideration include elastic and viscoelastic media with four different viscoelastic constitutive models, while the moving load is allowed to have a circular spatial distribution, which is more realistic for mimicking tire footprint than a commonly used point load. Efficient numerical algorithms based on fast evaluation of various integral transformations and their inversions are developed and validated through numerical example.

Download Full-text

Adapting Footfall Rhythmicity to Auditory Perturbations Affects Resilience of Locomotor Behavior: A Proof-of-Concept Study

Frontiers in Neuroscience ◽

10.3389/fnins.2021.678965 ◽

2021 ◽

Vol 15 ◽

Author(s):

Deepak K. Ravi ◽

Caroline C. Heimhofer ◽

William R. Taylor ◽

Navrag B. Singh

Keyword(s):

Steady State ◽

Fall Risk ◽

Recovery Time ◽

Center Of Mass ◽

Locomotor Behavior ◽

Proof Of Concept ◽

Limited Information ◽

Novel Approach ◽

Temporal Adaptation ◽

The Mean

For humans, the ability to effectively adapt footfall rhythm to perturbations is critical for stable locomotion. However, only limited information exists regarding how dynamic stability changes when individuals modify their footfall rhythm. In this study, we recorded 3D kinematic activity from 20 participants (13 males, 18–30 years old) during walking on a treadmill while synchronizing with an auditory metronome sequence individualized to their baseline walking characteristics. The sequence then included unexpected temporal perturbations in the beat intervals with the subjects required to adapt their footfall rhythm accordingly. Building on a novel approach to quantify resilience of locomotor behavior, this study found that, in response to auditory perturbation, the mean center of mass (COM) recovery time across all participants who showed deviation from steady state (N = 15) was 7.4 (8.9) s. Importantly, recovery of footfall synchronization with the metronome beats after perturbation was achieved prior (+3.4 [95.0% CI +0.1, +9.5] s) to the recovery of COM kinematics. These results highlight the scale of temporal adaptation to perturbations and provide implications for understanding regulation of rhythm and balance. Thus, our study extends the sensorimotor synchronization paradigm to include analysis of COM recovery time toward improving our understanding of an individual’s resilience to perturbations and potentially also their fall risk.

Download Full-text