Pulse Modulation - A Novel Approach to Gradient-Based Flow Injection Techniques

2001 ◽  
Vol 66 (8) ◽  
pp. 1219-1237 ◽  
Author(s):  
Armando Herbelin ◽  
Jaromir Ruzicka
Keyword(s):  
Flow Injection ◽  
Small Volume ◽  
Gradient Methods ◽  
Flow Conditions ◽  
Pulse Modulation ◽  
Novel Approach ◽  
Gradient Based ◽  
Injection Techniques ◽  
Computer Controlled ◽  
Single Standard

Development of a novel system for generation of gradients in flow injection analysis by pulse modulation is described. These user-selectable gradients are created by computer-controlled mixing of two solutions with a total volume as low as 75 μl and can be delivered under incremental or continuous flow conditions. Applications such as automated, single-standard instrument calibration are expected to benefit from high-precision linear gradients (r2 = 0.99989, n = 55). Gradient methods in biochemisty and immunology such as kinetic measurement of biomolecular interactions will benefit from the small volume of these gradients, especially for analytes with limited availability.

Stable and Supported Semantics in Continuous Vector Spaces

2020 ◽  
Author(s):  
Yaniv Aspis ◽  
Krysia Broda ◽  
Alessandra Russo ◽  
Jorge Lobo
Keyword(s):  
Logic Program ◽  
Matrix Multiplication ◽  
Vector Spaces ◽  
Continuous Space ◽  
Continuous Vector ◽  
Novel Approach ◽  
Gradient Based ◽  
Normal Logic ◽  
Parameter Values ◽  
Normal Logic Program

We introduce a novel approach for the computation of stable and supported models of normal logic programs in continuous vector spaces by a gradient-based search method. Specifically, the application of the immediate consequence operator of a program reduct can be computed in a vector space. To do this, Herbrand interpretations of a propositional program are embedded as 0-1 vectors in $\mathbb{R}^N$ and program reducts are represented as matrices in $\mathbb{R}^{N \times N}$. Using these representations we prove that the underlying semantics of a normal logic program is captured through matrix multiplication and a differentiable operation. As supported and stable models of a normal logic program can now be seen as fixed points in a continuous space, non-monotonic deduction can be performed using an optimisation process such as Newton's method. We report the results of several experiments using synthetically generated programs that demonstrate the feasibility of the approach and highlight how different parameter values can affect the behaviour of the system.

scholarly journals Gradient-based selection of cross sections: a novel approach for optimal frame structure design

2017 ◽  
Vol 56 (5) ◽  
pp. 959-972 ◽  
Author(s):  
Christian Krogh ◽  
Mathias H. Jungersen ◽  
Erik Lund ◽  
Esben Lindgaard
Keyword(s):  
Cross Sections ◽  
Structure Design ◽  
Frame Structure ◽  
Novel Approach ◽  
Gradient Based ◽  
Selection Of

scholarly journals Assessing Variations in Areal Organization for the Intrinsic Brain: From Fingerprints to Reliability

2016 ◽  
Author(s):  
Ting Xu ◽  
Alexander Opitz ◽  
R. Cameron Craddock ◽  
Margaret Wright ◽  
Xi-Nian Zuo ◽  
...  
Keyword(s):  
Individual Variation ◽  
Brain Function ◽  
Intraclass Correlation ◽  
Resting State Fmri ◽  
Single Individual ◽  
Initial Application ◽  
Novel Approach ◽  
Gradient Based ◽  
Healthy Participants

AbstractResting state fMRI (R-fMRI) is a powerful in-vivo tool for examining the functional architecture of the human brain. Recent studies have demonstrated the ability to characterize transitions between functionally distinct cortical areas through the mapping of gradients in intrinsic functional connectivity (iFC) profiles. To date, this novel approach has primarily been applied to iFC profiles averaged across groups of individuals, or in one case, a single individual scanned multiple times. Here, we used a publically available R-fMRI dataset, in which 30 healthy participants were scanned 10 times (10 minutes per session), to investigate differences in full-brain transition profiles (i.e., gradient maps, edge maps) across individuals, and their reliability. 10-minute R-fMRI scans were sufficient to achieve high accuracies in efforts to “fingerprint” individuals based upon full-brain transition profiles. Regarding testretest reliability, the image-wise intraclass correlation coefficient (ICC) was moderate, and vertex-level ICC varied depending on region; larger durations of data yielded higher reliability scores universally. Initial application of gradient-based methodologies to a recently published dataset obtained from twins suggested inter-individual variation in areal profiles might have genetic and familial origins. Overall, these results illustrate the utility of gradient-based iFC approaches for studying inter-individual variation in brain function.

scholarly journals A Penalized Linear and Nonlinear Combined Conjugate Gradient Method for the Reconstruction of Fluorescence Molecular Tomography

2007 ◽  
Vol 2007 ◽  
pp. 1-19 ◽  
Author(s):  
Shang Shang ◽  
Jing Bai ◽  
Xiaolei Song ◽  
Hongkai Wang ◽  
Jaclyn Lau
Keyword(s):  
Conjugate Gradient Method ◽  
Conjugate Gradient ◽  
Gradient Method ◽  
Optimization Problems ◽  
Gradient Methods ◽  
Reconstruction Algorithms ◽  
Fluorescence Molecular Tomography ◽  
Nonlinear Conjugate Gradient Method ◽  
Gradient Based ◽  
Linear And Nonlinear

Conjugate gradient method is verified to be efficient for nonlinear optimization problems of large-dimension data. In this paper, a penalized linear and nonlinear combined conjugate gradient method for the reconstruction of fluorescence molecular tomography (FMT) is presented. The algorithm combines the linear conjugate gradient method and the nonlinear conjugate gradient method together based on a restart strategy, in order to take advantage of the two kinds of conjugate gradient methods and compensate for the disadvantages. A quadratic penalty method is adopted to gain a nonnegative constraint and reduce the illposedness of the problem. Simulation studies show that the presented algorithm is accurate, stable, and fast. It has a better performance than the conventional conjugate gradient-based reconstruction algorithms. It offers an effective approach to reconstruct fluorochrome information for FMT.

Flow Injection Techniques for the in situ Monitoring of Marine Processes

2002 ◽  
pp. 385-402 ◽  
Author(s):  
P. J. Worsfold ◽  
E. P. Achterberg ◽  
A. R. Bowie ◽  
R. Sandford ◽  
V. Cannizzaro ◽  
...  
Keyword(s):  
Flow Injection ◽  
In Situ Monitoring ◽  
Injection Techniques

Advances in High-Speed Linear Design Technology: Novel Approach to Sidewall Geometry Design for Erosion Tests

2019 ◽  
Author(s):  
Maksim Sokolov ◽  
Max Lorenz ◽  
Mirco Rostamian ◽  
Christian Koch ◽  
Matthias Weissschuh ◽  
...  
Keyword(s):  
High Speed ◽  
Solid Particles ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Suction System ◽  
Erosion Testing ◽  
Geometry Design ◽  
Novel Approach ◽  
Design Paradigm ◽  
High Level

Abstract Test rigs for compressor cascade testing reported in literature are characterized by a high level of complexity. This is especially the case if a variable incidence should be allowed for or the flow conditions reach transonic or supersonic flow regimes. Incidence alteration capability is preferable for obtaining a more comprehensive picture of cascade properties. However, it necessitates a complex kinematic set-up in order to rotate the blades and to adjust the sidewall setting such that flow periodicity across the passages is ensured. Additionally, a complex sealing system is usually required to guarantee minimum flow disturbance. Often, a suction system is also introduced for boundary layer control and regulation of flow conditions. In the case of erosion testing the situation is exacerbated as the application of such conventional adjustment devices is ruled out due to the presence of solid particles in the flow. In this work an investigation of a new cascade design for erosion testing with variable incidence was conducted. A fixed sidewall geometry is proposed which ensures periodic flow conditions in the speed range of M = 0.5 up to M = 0.78 while allowing incidence adjustments in the range of i = ±10° as assessed by means of CFD. The novel design paradigm enables such flexibility by virtue of a self-regulating flow induced by flow separation from the fixed sidewall geometry. The latter has the benefit of not requiring a specialized mechanical setup and sealing due to the absence of movable parts in the flow. The calculated results show acceptable periodicity of various flow parameters within the passage at 50 percent blade height for all incidence settings considered. The conducted investigation has demonstrated that specially designed fixed sidewalls may enable sufficiently accurate transonic erosion testing under various incidence angles while making cascade erosion testing more economical and time efficient.

Construction and Validation of a Complaint Model of the Cerebrospinal Fluid System With Fluid Filled Syrinx

2004 ◽  
Author(s):  
Bryn A. Martin ◽  
Wojciech Kalata ◽  
John N. Oshinski ◽  
Francis Loth ◽  
Thomas J. Royston
Keyword(s):  
Cerebrospinal Fluid ◽  
External Environment ◽  
Mri Imaging ◽  
Flow Waveform ◽  
Flow Conditions ◽  
Model Geometry ◽  
Computer Controlled ◽  
Processing Techniques ◽  
Flow Waveforms

A simplified model of the cerebrospinal fluid (CSF) system with compliant fluid filled syrinx has been constructed, tested, and verified to closely mimic the in-vivo flow conditions observed through MRI imaging of the pathological CSF system with syringomyelia. The model is subjected to a MRI derived CSF flow waveform from a patient with Syringomyelia through use of a computer controlled pulsatile pump. Model geometry, flow waveform, and spinal cord compliance are obtained at three axial locations along the system through MRI image processing techniques. MRI testing was conducted with the syrinx open and closed to the external environment. Results indicate that the internal and external flow waveforms were in opposite directions when the syrinx was closed and in unison when the syrinx was open. The observed flow waveform and compliance measurements closely mimicked the in-vivo case when the syrinx is open to the external environment.

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