RESUMO
This paper presents a novel optofluidic Michelson interferometer based on droplet microfluidics used to create a droplet grating. The droplet grating is formed by a stream of plugs in the microchannel with constant refractive index variation. It has a real-time tunability in the grating period through varying the flow rates of the liquids and index variation via different combinations of liquids. The optofluidic Michelson interferometer is highly sensitive and is suitable for the measurement of biomedical and biochemical buffer solutions. The experimental results show that it has a sensitivity of 66.7 nm per refractive index unit (RIU) and a detection range of 0.086 RIU.
Assuntos
Técnicas Biossensoriais/instrumentação , Interferometria/instrumentação , Técnicas Analíticas Microfluídicas/instrumentação , Dispositivos Ópticos , Refratometria/instrumentação , Desenho de Equipamento , Análise de Falha de EquipamentoRESUMO
This paper presents a two coupled oscillators model to describe the dynamics of a tuning fork with a probe attached. The two coupled oscillators are unbalanced only in their effective masses and the damping ratios. By applying a frequency domain system identification approach in experimental investigation of various probe attachment cases, a good accuracy of the model is demonstrated. The effectiveness of the model is further demonstrated in quantitative analysis of the noise performance and the sensitivity of force sensing with a tuning fork probe. Compared with existing models, the proposed model can more accurately characterize the dynamics of a tuning fork probe.
RESUMO
We present a multiple compartment, mammillary distributed-parameter model for capillary-tissue exchange, which can be implemented with dynamic contrast-enhanced imaging to study kinetic heterogeneity in tumors. The proposed n-compartment model consists of a vascular distributed-parameter compartment in direct exchange with a number (n - 1) of interstitial compartments. It is applied to a prostate tumor case study to illustrate the possible co-existence of two kinetically distinct compartments in the tumor, and the estimation of useful physiological parameters (such as perfusion, mean transit time, fractional volumes, and transfer and rate constants) associated with tissue microcirculation. The present model exhibits the convenient property of a separable impulse residue response function in time domain, which can be used to provide further insights and understanding on the physiological basis of tissue enhancement parameters commonly used for correlation studies with tumor histological diagnosis.
Assuntos
Capilares/fisiopatologia , Meios de Contraste/farmacocinética , Modelos Cardiovasculares , Neoplasias/irrigação sanguínea , Neoplasias/fisiopatologia , Neoplasias da Mama/irrigação sanguínea , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/fisiopatologia , Humanos , Aumento da Imagem/métodos , Cinética , Imageamento por Ressonância Magnética/métodos , Masculino , Neoplasias/diagnóstico , Neoplasias da Próstata/irrigação sanguínea , Neoplasias da Próstata/diagnóstico , Neoplasias da Próstata/fisiopatologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Distribuição Tecidual , Tomografia Computadorizada por Raios X/métodosRESUMO
A robust backpropagation training algorithm with a dead zone scheme is used for the online tuning of the neuralnetwork (NN) tracking control system. This assures the convergence of the multilayered NN in the presence of disturbance. It is proved in this paper that the selection of a smaller range of the dead zone leads to a smaller estimate error of the NN, and hence a smaller tracking error of the NN tracking controller. The proposed algorithm is applied to a three-layered network with adjustable weights and a complete convergence proof is provided. The results can also be extended to the network with more hidden layers.