414 research outputs found
Registration of brain tumor images using hyper-elastic regularization
In this paper, we present a method to estimate a deformation
field between two instances of a brain volume having tumor. The novelties
include the assessment of the disease progress by observing the healthy tissue
deformation and usage of the Neo-Hookean strain energy density model as
a regularizer in deformable registration framework. Implementations on synthetic
and patient data provide promising results, which might have relevant
use in clinical problems
Cellular automata segmentation of brain tumors on post contrast MR images
In this paper, we re-examine the cellular automata(CA) al- gorithm to show that the result of its state evolution converges to that of the shortest path algorithm. We proposed a complete tumor segmenta- tion method on post contrast T1 MR images, which standardizes the VOI and seed selection, uses CA transition rules adapted to the problem and evolves a level set surface on CA states to impose spatial smoothness. Val- idation studies on 13 clinical and 5 synthetic brain tumors demonstrated the proposed algorithm outperforms graph cut and grow cut algorithms in all cases with a lower sensitivity to initialization and tumor type
Oddity in nonrelativistic, strong gravity
We consider the presence of odd powers of the speed of light in the
covariant nonrelativistic expansion of General Relativity (GR). The term of
order in the relativistic metric is a vector potential that contributes at
leading order in this expansion and describes strong gravitational effects
outside the (post-)Newtonian regime. The nonrelativistic theory of the leading
order potentials contains the full non-linear dynamics of the stationary sector
of GR.Comment: 24 pages + appendices. Version accepted for publication by EPJC.
Subsection 4.4 on possible phenomenological applications adde
Controller design for integrating processes with Coefficient Diagram Method
Bu çalıĆmanın amacı, transfer fonksiyonunda integratör bulunan zaman gecikmeli sistemlerin kontrolünde klasik PID kontrolörlerin sınırlılıklarını göstermektir. Bu nedenle, bu tür sistemler için daha iyi bir davranÄ±Ć elde etmek amacıyla Katsayı Diyagram Metodu (KDM) olarak adlandırılan bir polinomsal yaklaĆımın kullanılması önerilmiĆtir. KDM ile kontrolör tasarımı eĆdeÄer zaman sabiti, kararlılık indeksi ve karalılık sınır indeksi gibi uygun davranÄ±Ć kriterlerine karĆı kapalı çevrim sisteminin karakteristik polinomunun katsayılarını seçmeye dayalıdır. Yapılan tasarım örneÄi KDM’in hem referans basamak giriĆin takibi ve hem de bozucu iĆaretin söndürülmesi için davranıĆta önemli bir iyileĆme saÄladıÄını göstermiĆtir. Ayrıca kontrol en kısa yerleĆme süresini ve parametre deÄiĆimlerine karĆı en dayanıklı davranıĆı saÄlamıĆtır. Anahtar Kelimeler: Katsayı Diyagram Metodu, zaman gecikmesi, integratörlü sistemler, dayanıklılık.The objective of this paper is to illustrate the limitations of classical PID controllers in controlling time delay systems with integrating transfer functions. Generally, the control of integrating processes is more difficult than the classical stable open-loop processes. Especially, integrating processes existing time delay make difficult the control operation. Numerous PID strategies have been proposed for these systems recently. Therefore, using a polynomial approach, Coefficient Diagram Method (CDM) has been proposed in order to obtain a better performance for these systems. The controller design by CDM is based on the choice of the coefficients of the characteristic polynomial of the closed loop system according to the convenient performance criteria such as equivalent time constant, stability index, and stability limit index. The studies on this method illustrated that the CDM provides a significantly improved performance both for the reference step input tracking and for the disturbance rejection. Also the control system provides the smallest settling time and the most robust performance to the parameter changes. An example are presented for an integrating process with time delay to illustrate the effectiveness of the proposed method and compared it with existing ones. It is shown that CDM design is more stable and robust whilst giving the desired time domain performance.Keywords: Coefficient Diagram Method, time delay, integrating processes, robustness
On the Selection of Tuning Methodology of FOPID Controllers for the Control of Higher Order Processes
In this paper, a comparative study is done on the time and frequency domain
tuning strategies for fractional order (FO) PID controllers to handle higher
order processes. A new fractional order template for reduced parameter modeling
of stable minimum/non-minimum phase higher order processes is introduced and
its advantage in frequency domain tuning of FOPID controllers is also
presented. The time domain optimal tuning of FOPID controllers have also been
carried out to handle these higher order processes by performing optimization
with various integral performance indices. The paper highlights on the
practical control system implementation issues like flexibility of online
autotuning, reduced control signal and actuator size, capability of measurement
noise filtration, load disturbance suppression, robustness against parameter
uncertainties etc. in light of the above tuning methodologies.Comment: 27 pages, 10 figure
Bis(acetato-ÎșO)bisÂ[2-(pyridin-2-yl)ethanol-Îș2 N,O]copper(II)
The title compound, [Cu(CH3COO)2(C7H9NO)2], is a monomeric complex with an octaÂhedral geometry. The CuII atom is located on an inversion center and is coordinated by acetate and 2-(pyridin-2-yl)ethanol ligands. The acetate group is coordinated in a monodentate manner, while the 2-(pyridin-2-yl)ethanol is coordinated as a bidentate ligand involving the endocyclic N atom and the hyÂdroxy O atom of the ligand side chain. An intraÂmolecular hydrogen bond is observed between the hyÂdroxy O atom and the non-coordinated acetate O atom. No classical interÂmolecular hydrogen-bond contacts were observed. However, the crystal packing is effected by CâHâŻO interÂactions, which link the mononuclear entities into layers parallel to the bc plane
EFFECTS OF ORTHODONTIC ADHESIVE MATERIALS ON S. MUTANS AND LACTOBACILLI LEVELS IN HUMAN SALIVA
ABSTRAC
Diffusion-Based Hierarchical Multi-Label Object Detection to Analyze Panoramic Dental X-rays
Due to the necessity for precise treatment planning, the use of panoramic
X-rays to identify different dental diseases has tremendously increased.
Although numerous ML models have been developed for the interpretation of
panoramic X-rays, there has not been an end-to-end model developed that can
identify problematic teeth with dental enumeration and associated diagnoses at
the same time. To develop such a model, we structure the three distinct types
of annotated data hierarchically following the FDI system, the first labeled
with only quadrant, the second labeled with quadrant-enumeration, and the third
fully labeled with quadrant-enumeration-diagnosis. To learn from all three
hierarchies jointly, we introduce a novel diffusion-based hierarchical
multi-label object detection framework by adapting a diffusion-based method
that formulates object detection as a denoising diffusion process from noisy
boxes to object boxes. Specifically, to take advantage of the hierarchically
annotated data, our method utilizes a novel noisy box manipulation technique by
adapting the denoising process in the diffusion network with the inference from
the previously trained model in hierarchical order. We also utilize a
multi-label object detection method to learn efficiently from partial
annotations and to give all the needed information about each abnormal tooth
for treatment planning. Experimental results show that our method significantly
outperforms state-of-the-art object detection methods, including RetinaNet,
Faster R-CNN, DETR, and DiffusionDet for the analysis of panoramic X-rays,
demonstrating the great potential of our method for hierarchically and
partially annotated datasets. The code and the data are available at:
https://github.com/ibrahimethemhamamci/HierarchicalDet.Comment: MICCAI 202
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