Search results for "Control system"

Trajectory Decentralized Fuzzy Control of Multiple UAVs.

2008

This paper considers a complete position and heading rate control system for multiple unmanned aerial vehicles (UAVs) with constant altitude. A decentralized trajectory planning algorithm is proposed, where the UAVs will avoid collisions while moving. In order to stabilize the UAVs in the reference planned trajectories and ensure the boundedness of the control velocities, a fuzzy control law is proposed with Lyapunov's stability proof. Simulation experiments developed in Matlab environment confirm the effectiveness and the robustness of the proposed control algorithm with respect to possible turbulence disturbances perturbing the nominal motion of the UAVs.

Dynamic Output-Feedback Passivity Control for Fuzzy Systems under Variable Sampling

2013

Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://dx.doi.org/10.1155/2013/767093 Open Access This paper concerns the problem of dynamic output-feedback control for a class of nonlinear systems with nonuniform uncertain sampling via Takagi-Sugeno (T-S) fuzzy control approach. The sampling is not required to be periodic, and the state variables are not required to be measurable. A new type fuzzy dynamic output-feedback sampled-data controller is constructed, and a novel time-dependent Lyapunov-Krasovskii functional is chosen for fuzzy systems under variable sampling. By using Lyapunov stability theory, a sufficie…

ERP in small service companies

2013

The purpose of this thesis was to provide knowledge on the organizational and performance consequences of management control systems. The examination into prior literature yielded information on the benefits and challenges related to ERP systems, the position of ERP systems in the overall control environment of the company, and how ERP influences the ensemble of management control systems. By leaning to the prior work of Chapman and Kihn (2009), a survey research was conducted aiming to discover if information system integration (ISI) embedded in ERP supported the enabling approach to management control, and whether this in turn would result into higher performance and perceived system succ…

Microwave-free vector magnetometry with nitrogen-vacancy centers along a single axis in diamond

2019

Sensing vector magnetic fields is critical to many applications in fundamental physics, bioimaging, and material science. Magnetic-field sensors exploiting nitrogen-vacancy (NV) centers are particularly compelling as they offer high sensitivity and spatial resolution even at nanoscale. Achieving vector magnetometry has, however, often required applying microwaves sequentially or simultaneously, limiting the sensors' applications under cryogenic temperature. Here we propose and demonstrate a microwave-free vector magnetometer that simultaneously measures all Cartesian components of a magnetic field using NV ensembles in diamond. In particular, the present magnetometer leverages the level ant…

Comparison of Diffusion MRI Acquisition Protocols for the In Vivo Characterization of the Mouse Spinal Cord: Variability Analysis and Application to …

2016

Diffusion-weighted Magnetic Resonance Imaging (dMRI) has relevant applications in the microstructural characterization of the spinal cord, especially in neurodegenerative diseases. Animal models have a pivotal role in the study of such diseases; however, in vivo spinal dMRI of small animals entails additional challenges that require a systematical investigation of acquisition parameters. The purpose of this study is to compare three acquisition protocols and identify the scanning parameters allowing a robust estimation of the main diffusion quantities and a good sensitivity to neurodegeneration in the mouse spinal cord. For all the protocols, the signal-to-noise and contrast-to noise ratios…

Nonceliac wheat sensitivity in the context of multiple food hypersensitivity: new data from confocal endomicroscopy.

2015

Dear Editor, We enjoyed reading the article by Fritscher-Ravens et al who showed, by confocal endomicroscopy, that candidate food antigens caused immediate duodenal mucosa damage in irritable bowel syndrome (IBS) patients with a prolonged clinical history of symptoms after meals. Their in vivo data add evidence to the relationship between IBS and food allergy and seem to reinforce our hypothesis that a percentage of “nonceliac wheat sensitive” (NCWS) -patients with an IBS-like clinical presentation could suffer from non-immunoglobulin E-mediated wheat allergy. However, we would suggest that the very high percentage of positive confocal laser endomicroscopy patients (CLE) -22 out of 36- foun…

Non-celiac wheat sensitivity as an allergic condition: personal experience and narrative review.

2013

Non-celiac wheat sensitivity (NCWS) is a newly described clinical entity characterized by symptoms, which can involve the gastrointestinal tract, the nervous system, the skin, and other organs. There is little data on the pathogenesis of NCWS and it is probable that different pathogenic mechanisms are involved in the different clinical manifestations of the disease. The only common denominator of NCWS "syndrome" is wheat consumption: the symptoms disappear on exclusion of wheat from the diet, and reappear on wheat consumption. The objective of this study was to review our prior data regarding NCWS and to review relevant medical literature regarding NCWS, with particular attention to the hyp…

Contrast sensitivity of the visual system in speckle imagery

1994

The contrast sensitivity function (CSF) of the whole visual system is determined with the use of coherent diffuse illumination. This function provides supplementary data about the effect of speckle on the ability of the visual system to perceive the spatial information contained in an image. The results show that speckle not only prevents perception of the finest details (highest frequencies) but also reduces the visibility of lower frequencies (especially where contrast is low). The difference between the CSF's determined with and without speckle is quantitatively very important. And the ratio between the two CSF's is a measure of the retinal ability to perceive contrast in the presence of…

Non-celiac wheat sensitivity is a more appropriate label than non-celiac gluten sensitivity.

2013

Repeatability and sensitivity of passive mechanical stiffness measurements in the triceps surae muscle‐tendon complex

2021

Measurements of muscle-tendon unit passive mechanical properties are often used to illustrate acute and chronic responses to a training stimulus. The purpose of this study was to quantify the inter-session repeatability of triceps surae passive stiffness measurements in athletic and non-athletic populations, with the view to discussing its usefulness both as a muscle-tendon profiling tool and a control measure for studies with multiple data collection sessions. The study also aimed to observe the effects of quiet standing on passive stiffness parameters. Twenty-nine men (10 cyclists, nine triathletes, 10 controls) visited the laboratory on three separate occasions, where passive stiffness t…