Adaptive filtering of evoked potentials with radial-basis-function neural network prefilter

Evoked potentials (EPs) are time-varying signals typically buried in relatively large background noise. To extract the EP more effectively from noise, we had previously developed an approach using an adaptive signal enhancer (ASE) (Chen et al., 1995). ASE requires a proper reference input signal for its optimal performance. Ensemble- and moving window-averages were formerly used with good results. In this paper, we present a new method to provide even more effective reference inputs for the ASE. Specifically, a Gaussian radial basis function neural network (RBFNN) was used to preprocess raw EP signals before serving as the reference input. Since the RBFNN has built-in nonlinear activation functions that enable it to closely fit any function mapping, the output of RBFNN can effectively track the signal variations of EP. Results confirmed the superior performance of ASE with RBFNN over the previous method.     

A new generalized particle approach to parallel bandwidth allocation

This paper presents a new generalized particle (GP) approach to dynamical optimization of network bandwidth allocation, which can also be used to optimize other resource assignments in networks. By using the GP model, the complicated network bandwidth allocation problem is transformed into the kinematics and dynamics of numerous particles in two reciprocal dual force-fields. The proposed model and algorithm are featured by the powerful processing ability under a complex environment that involves the various interactions among network entities, the market mechanism between the demands and service, and other phenomena common in networks, such as congestion, metabolism, and breakdown of network entities. The GP approach also has the advantages in terms of the higher parallelism, lower computation complexities, and the easiness for hardware implementation. The properties of the approach, including the correctness, convergency and stability, are discussed in details. Simulation results attest to the effectiveness and suitability of the proposed approach.     

A dielectrophoretic chip packaged at wafer level

The paper presents a dielectrophoretic chip, fully enclosed, with bulk silicon electrodes fabricated using wafer-to-wafer bonding techniques and packaged at the wafer level. The silicon electrodes, which are bonded to two glass dies, define in the same time the walls of the microfluidic channel. The device is fabricated from a silicon wafer that is bonded (at wafer level) anodically and using SU8 photoresist between two glass wafers. The first glass die includes drilled holes for inlet/outlet connections while the second glass die assure the electrical connections, through via holes and a metallization layer, between the silicon electrodes and a printing circuit board.     

Defect-free wet etching through pyrex glass using Cr/Au mask

This paper reports the highest etch depth of annealed Pyrex glass achieved by wet etching in highly concentrated HF solution, using a low stress chromium–gold with assistance of photoresist as masking layer. The strategies to achieve that are: increasing the etch rate of glass and simultaneously increasing the resistance of Cr/Au mask in the etchant. By annealing the Pyrex glass and using a highly concentrated HF acid, a high etch rate can be obtained. Furthermore, a method to achieve a good resistance of the Cr/Au masking layer in the etching solution is to control the residual stress and to increase the thickness of Au deposition up to 1 μm. In addition, the presence of a hard baked photoresist can improve the etching performance. As a result, a 500-μm thick Pyrex glass wafer was etched through.

     

高强混凝土新型梁柱节点构造的抗震性能试验研究

针对低-中震害区构件有限延性的要求,提出了2种新型钢筋混凝土梁柱节点的构造形式:在节点区加配斜钢筋,或梁主钢筋在节点区弯起.它们既可满足有限延性的要求,又可避免节点区钢筋密集.通过对4个高强混凝土梁柱节点在低周反复荷载作用的试验表明:2种新型节点均可提高节点延性,将节点的位移延性系数分别从3提高到3.5和4.4;在节点区加配斜钢筋的试件可提高强度15%.因此,对于有限延性要求的节点,是最佳的节点构造形式.     

Linking learning goals and educational resources through interactive concept map visualizations

Concept browsing interfaces can help educators and learners to locate and use learning resources that are aligned with recognized learning goals. The Strand Map Service enables users to navigate interactive visualizations of related learning goals and to request digital library resources aligned with learning goals. These interfaces are created using a programmatic Web service interface that dynamically generates interactive visual components. Preliminary findings suggest that these library interfaces appear to help users stay focused on the scientific content of their information discovery task, as opposed to focusing on the mechanics of searching.     

Satellite-derived parameters for biological modelling in coastal waters: Illustration over the eastern continental shelf of the Bay of Biscay

In biological modelling of the coastal phytoplankton dynamics, the light attenuation coefficient is often expressed as a function of the concentrations of chlorophyll and mineral suspended particulate matter (SPM). In order to estimate the relationship between these parameters over the continental shelf of the northern Bay of Biscay, a set of in situ data has been gathered for the period 1998-2003 when SeaWiFS imagery is available. These data comprise surface measurements of the concentrations of total SPM, chlorophyll, and irradiance profiles from which is derived the attenuation coefficient of the photosynthetically available radiation, K_PAR. The performance of the IFREMER look-up table used to retrieve the chlorophyll concentration from the SeaWiFS radiance is evaluated on this new set of data. The quality of the estimated chlorophyll concentration is assessed from a comparison of the variograms of the in situ and satellite-derived chlorophyll concentrations. Once the chlorophyll concentration is determined, the non living SPM, which is defined as the SPM not related to the dead or alive endogenous phytoplankton, is estimated from the radiance at 555 nm by inverting a semi-analytic model. This method provides realistic estimations of concentrations of chlorophyll and SPM over the continental shelf all over the year. Finally, a relationship, based on non living SPM and chlorophyll, is proposed to estimate K_PAR on the continental shelf of the Bay of Biscay. The same formula is applied to non living SPM and chlorophyll concentrations, observed in situ or derived from SeaWiFS radiance.     

Data Distribution in a Peer to Peer Storage System

This article presents distributions for data storage in a P2P system. In peer to peer storage system we have to face a continuous stream of peer failures. So to insure data durability data are usually disseminated using a dispersal redundant scheme and a dynamic data reconstruction process is used to rebuild lost data. There is an important communication traffic to maintain data integrity. So, it is important to reduce the impact of this reconstruction process on peer. To minimize end user traffic according to the reconstruction process, distribution must take into account a new measure: The maximum disturbance cost of a peer. To begin with, we define a static distribution scheme which minimizes this reconstruction cost based on prime numbers theory. We compare this distribution with the random distribution, the most used in data distribution.This Project () is supported by the ACI GRID CGP2P and the ACI MD GDX.     

ε-Descending Support Vector Machines for Financial Time Series Forecasting

This paper proposes a modified version of support vector machines (SVMs), called ε-descending support vector machines (ε-DSVMs), to model non-stationary financial time series. The ε-DSVMs are obtained by incorporating the problem domain knowledge – non-stationarity of financial time series into SVMs. Unlike the standard SVMs which use a constant tube in all the training data points, the ε-DSVMs use an adaptive tube to deal with the structure changes in the data. The experiment shows that the ε-DSVMs generalize better than the standard SVMs in forecasting non-stationary financial time series. Another advantage of this modification is that the ε-DSVMs converge to fewer support vectors, resulting in a sparser representation of the solution. This revised version was published online in June 2006 with corrections to the Cover Date.