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991.
The complex local mean decomposition 总被引:3,自引:0,他引:3
The local mean decomposition (LMD) has been recently developed for the analysis of time series which have nonlinearity and nonstationarity. The smoothed local mean of the LMD surpasses the cubic spline method used by the empirical mode decomposition (EMD) to extract amplitude and frequency modulated components. To process complex-valued data, we propose complex LMD, a natural and generic extension to the complex domain of the original LMD algorithm. It is shown that complex LMD extracts the frequency modulated rotation and envelope components. Simulations on both artificial and real-world complex-valued signals support the analysis. 相似文献
992.
Bumhwi KimAuthor Vitae 《Neurocomputing》2011,74(4):646-655
A new incrementally growing neural network model, called the growing fuzzy topology ART (GFTART) model, is proposed based on integrating the conventional fuzzy ART model with the incremental topology-preserving mechanism of the growing cell structure (GCS) model. This is in addition, to a new training algorithm, called the push-pull learning algorithm. The proposed GFTART model has two purposes: First, to reduce the proliferation of incrementally generated nodes in the F2 layer by the conventional fuzzy ART model based on replacing each F2 node with a GCS. Second, to enhance the class-dependent clustering representation ability of the GCS model by including the categorization property of the conventional fuzzy ART model. In addition, the proposed push-pull training algorithm enhances the cluster discriminating property and partially improves the forgetting problem of the training algorithm in the GCS model. 相似文献
993.
994.
A.-C. SalaünAuthor Vitae F. Le BihanAuthor VitaeT. Mohammed-BrahimAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):138-143
High sensitivity to chemical species of sub-micron gap Suspended-Gate FETs (more than 200 mV/pH for example) is explained from the charge distribution induced by the high field in the sub-micronic gap under the gate-bridge. Modeling of Metal-Electrolyte-Insulator-Silicon (MEIS) capacitor, which is the basic vertical structure of the transistor, is performed to highlight this effect through the response to the pH change of the solution filling the gap. The analytical model is based on the 2D-numerical resolution of Poisson's equation. The response of quasi-static C(V) plots versus pH is simulated using both electrolyte charge distribution and site-binding theory considering the influence of sites densities on silicon nitride. Device modeling and simulated/experimental electrical characteristics are presented. Effect of the gap thickness on the pH sensitivity is also discussed in this study. 相似文献
995.
E.N. ArmstrongAuthor VitaeT. StrikerAuthor Vitae V. RamaswamyAuthor VitaeJ.A. RuudAuthor Vitae E.D. WachsmanAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):159-170
NOx adsorption behavior on LaFeO3 (LFO) and LaMnO3+δ (LMO) was characterized using temperature controlled methods and mass spectrometry. Temperature program desorption revealed decomposition of complex surface species formation when NO or NO2 was adsorbed on LFO and LMO. LFO exhibited higher adsorption capacity for NOx species than LMO and was shown to be more active for NOx surface conversion. Both effects were attributed to the different B-site cations, with iron in LFO in the 3+ valence state, and manganese in LMO in the 3+ and 4+ valence states. Results from diffuse reflectance infrared spectroscopy were used to identify specific nitrite and nitrate species that are formed on the surfaces of LFO and LMO at room temperature. Temperature programmed reaction revealed a complex NO2 decomposition mechanism to NO and O2 for LFO and LMO in which the formation of nitrite and nitrate species serve as intermediates below ∼600 °C. NOx sensing mechanisms were considered and predicted based on the types and quantities of surface species formed. 相似文献
996.
R. Gómez-MartínezAuthor VitaeA. SánchezAuthor Vitae M. DuchAuthor VitaeJ. EsteveAuthor Vitae J.A. PlazaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,154(2):181-184
Microworld barcoding has become a promising tool for cell biology. Individual and subpopulation cell tracking is of great interest to evaluate cell behaviour. Nowadays, many micrometer and even nanometer size silicon structures can be fabricated using microelectronics techniques. In this work we report for first time the development of 3D barcodes based on silicon substrate. The proposed silicon micromachining technology based on deep reactive ion etching (DRIE) allows to obtain micrometer-sized cylindrical structures with vertical etch profile that defines a bit = 1 and non-vertical etch profile that defines a bit = 0. Although this technology will allow more than 15 bits representation, only 4-8 bits are necessary for cell labelling. The results of this work show that DRIE has become a versatile technique to produce high aspect 3D biocompatible silicon-based barcodes structures for cell studies. 相似文献
997.
Meng DengAuthor Vitae Xi YangAuthor VitaeMusa SilkeAuthor Vitae Weiming QiuAuthor VitaeMingsheng XuAuthor Vitae Gustaaf BorghsAuthor Vitae Hongzheng ChenAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):176-184
By exploiting the electrostatic interaction between positively charged pyrrole cation radicals and negatively charged graphene oxide (GO) sheets, we prepared polypyrrole/graphene oxide (PPy/GO) composite films by a one-step electrochemical process. We studied the effects of the polymerization current density and the GO content in electrolyte on the formation of PPy/GO coatings onto platinum neural microelectrode sites. As compared with pure PPy film, PPy/GO coatings show a rougher surface feature with micrometer-scale bulges. The impedance of the PPy/GO coated Pt electrode is only about 10% of the bare Pt electrode at the biological relevant 1 kHz, while the charge capacity density is more than two orders of the magnitude of the bare Pt electrode. Moreover, the PPy/GO coated Pt electrodes show higher performance than the PPy coated electrodes for the application of neural probe. 相似文献
998.
Min-Hsien WuAuthor Vitae Yu-Han ChangAuthor Vitae Yen-Ting LiuAuthor VitaeYan-Ming ChenAuthor Vitae Shih-Siou WangAuthor VitaeHsin-Yao WangAuthor Vitae Chao-Sung LaiAuthor VitaeTung-Ming PanAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):397-407
This study reports a microfluidic cell culture chip encompassing 36 microbioreactors for high throughput perfusion 3-dimensional (3D) cell culture-based chemosensitivity assays. Its advantages include the capability for multiplexed medium delivery, and the function for both efficient and high throughput micro-scale 3D culture construct preparation and loading. The results showed that the proposed medium pumping mechanism was able to provide a uniform pumping rates ranging from 1.2 to 3.9 μl h−1. In addition, the simple cell/hydrogel loading scheme has been proven to be able to carry out 3D cell culture construct preparation and loading precisely and efficiently. Furthermore, a chemosensitivity assay was successfully demonstrated using the proposed cell culture chip. The results obtained were also compared with the same evaluation based on a conventional 2D monolayer cell culture. It can be concluded that the choice of cell culture format can result in different chemosensitivity evaluation results. Overall, because of the nature of miniaturized perfusion 3D cell culture, the cell culture chip not only can provide stable, well-defined and more biologically relevant culture environments, but it also features low consumption of research resources. All these traits are found particularly useful for high-precision and high-throughput 3D cell culture-based assays. 相似文献
999.
E.V. MoiseevaAuthor VitaeA.A. FletcherAuthor Vitae C.K. HarnettAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):408-414
We report on a droplet-producing microfluidic system with electrical impedance-based detection. The microfluidic devices are made of polydimethylsiloxane (PDMS) and glass with thin film electrodes connected to an impedance-monitoring circuit. Immiscible fluids containing the hydrophobic and hydrophilic phases are injected with syringe pumps and spontaneously break into water-in-oil droplet trains. When a droplet passes between a pair of electrodes in a medium having different electrical conductivity, the resulting impedance change signals the presence of the particle for closed-loop feedback during processing. The circuit produces a digital pulse for input into a computer control system. The droplet detector allows estimation of a droplet's arrival time at the microfluidic chip outlet for dispensing applications. Droplet detection is required in applications that count, sort, and direct microfluidic droplets. Because of their low cost and simplicity, microelectrode-based droplet detection techniques should find applications in digital microfluidics and in three-dimensional printing technology for rapid prototyping and biotechnology. 相似文献
1000.
Sergio F. León-LuisAuthor VitaeUlises R. Rodríguez-MendozaAuthor Vitae Emmanuel LallaAuthor VitaeVíctor LavínAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):208-213
The temperature dependence of the green upconverted emission from the two thermally coupled 2H11/2 and 4S3/2 levels of the Er3+ ion in a fluorotellurite glass has been analyzed as a function of the optically active ion concentration in order to check its availability as a temperature sensor. The infrared-to-green upconverted emission have been observed by the naked eyes after a cw laser diode excitation at 800 nm. The fluorescence intensity ratio between the thermally coupled emitting levels as well as the temperature sensitivity has been experimentally obtained up to 540 K. A better behaviour as a temperature sensor has been obtained for the less Er3+ concentrated glass with a maximum sensitivity of 54 × 10−4 K−1 at 540 K, one of the highest found in rare-earth doped transparent materials. 相似文献