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91.
In this work we demonstrate that the basic equations of the Landau hydrodynamics may be derived directly from the quantum-mechanical microscopic N-body Hamiltonian, which is expressed as a functional of the local observables, namely, particle and current densities. The Landau quantum hydrodynamic equations are then the Heisenberg equations of motion of these quantities. 相似文献
92.
Modelling complex dynamic mechanical systems, such as PEMFC, without any physical models is a difficult challenge but it could allow the monitoring of endurance tests of fuel cell systems. Neural networks are recognised as powerful numerical tools for predicting complex and nonlinear dynamic behaviours. They require only data limited to experimental inputs and outputs but the choice of an adapted architecture is critical. This paper presents a method for defining a neural network architecture optimised for the fuel cell systems. The associated experimental conditions specifying the vibration tests to train and validate were defined. They consist of swept sinus as well as random excitation forces. The resulting simulations are presented and analysed. 相似文献
93.
Sonic spray (SS) ionization is a relatively novel atmospheric pressure ionization technique for LC/MS, based on the principle of "spray ionization", which only recently became commercially available. In this paper, we evaluate the performance of this ion source as an interface for LC/MS in comparison with the more traditional and better studied pneumatically assisted electrospray or ion spray (IS). The effect of organic modifiers, volatile acids, and buffer systems in the LC eluent on the ionization efficiency of both interfaces is described and some possible explanations for the observed phenomena are highlighted. We could conclude that the presence of organic solvents gradually increased the ionization efficiency for IS and SS, while volatile acids or buffers gave a significant signal suppression. Furthermore, we present the application of the sonic spray interface to a fast LC/MS analysis, for the simultaneous determination of the seven prime opium alkaloids in heroin impurity profiling. Chromatographic separation is performed in 5 min on a monolithic silica column (Chromolith Performance) with a gradient elution system and an optimized flow of 5 mL/min. By means of a postcolumn split of approximately 1/20, a coupling between the fast LC system and the mass spectrometer is made. The method is validated and successfully applied to the analysis of real-time seized heroin street samples. 相似文献
94.
Impact of serum and dialysates obtained from chronic hemodialysis patients maintained on high cut‐off membranes on inflammation profile in human THP‐1 monocytes 下载免费PDF全文
Bogusz Trojanowicz Christof Ulrich Roman Fiedler Markus Storr Torsten Boehler Peter Martus Michael Pawlak Marcus A. Glomb Christian Henning Markus Templin Kristin Werner Daniel Zickler Kevin Willy Ralf Schindler Matthias Girndt 《Hemodialysis international. International Symposium on Home Hemodialysis》2017,21(3):348-358
95.
Two Methods for Optimal MECG Elimination and FECG Detection from Skin Electrode Signals 总被引:1,自引:0,他引:1
Vanderschoot Jan Callaerts Dirk Sansen Willy Vandewalle Joos Vantrappen Gaston Janssens Jozef 《IEEE transactions on bio-medical engineering》1987,(3):233-243
Two signal processing techniques for the suppression of the maternal ECG and simultaneously optimal detection of fetal ECG with respect to noise are presented. Both techniques are based on the singular value decomposition of a measurement matrix. Criteria are given in order to evaluate, a priori, electrode locations and sampling schemes for both methods. A fundamental difference with other methods is that the number of linearly independent FECG signals is not constrained to one. One of the presented techniques is a typical offline method. It is well suited for a large number of electrodes and large number of samples, which results in a better signal to noise ratio. The second technique is a typical on-line method. It gives fetal ECG signals within about 1 s, and is adaptive to changes of the transfer (e.g., due to fetal movement). It can be applied with a small number of electrodes (e.g., eight). It is shown that if three of these signals are from thoracic electrodes, the MECG suppression is guaranteed. 相似文献
96.
Bo Qin Qian-Hong Wu Willy Susilo Yi Mu Yu-Min Wang and Zheng-Tao Jiang 《计算机科学技术学报》2007,22(6):805-821
We propose short group signature (GS) schemes which are provably secure without random oracles. Our basic scheme is about 14 times shorter than the Boyen-Waters GS scheme at Eurocrypt 2006, and 42% shorter than the recent GS schemes due to Ateniese et al. The security proofs are provided in the Universally Composable model, which allows the proofs of security valid not only when our scheme is executed in isolation, but also in composition with other secure cryptographic primitives. We also present several new computational assumptions and justify them in the generic group model. These assumptions are useful in the design of high-level protocols and may be of independent interest. 相似文献
97.
Y. Charlie Hu Honghui Lu Alan L. Cox Willy Zwaenepoel 《Journal of Parallel and Distributed Computing》2000,60(12):160
In this paper, we present the first system that implements OpenMP on a network of shared-memory multiprocessors. This system enables the programmer to rely on a single, standard, shared-memory API for parallelization within a multiprocessor and between multiprocessors. It is implemented via a translator that converts OpenMP directives to appropriate calls to a modified version of the TreadMarks software distributed shared-memory (SDSM) system. In contrast to previous SDSM systems for SMPs, the modified TreadMarks system uses POSIX threads for parallelism within an SMP node. This approach greatly simplifies the changes required to the SDSM in order to exploit the intranode hardware shared memory. We present performance results for seven applications (Barnes-Hut, CLU, and Water from SPLASH-2, 3D-FFT from NAS, Red-Black SOR, TSP, and MGS) running on an SP2 with four four-processor SMP nodes. A comparison between the thread implementation and the original implementation of TreadMarks shows that using the hardware shared memory within an SMP node significantly reduces the amount of data and the number of messages transmitted between nodes and consequently achieves speedups that are up to 30% better than the original versions. We also compare SDSM against message passing. Overall, the speedups of multithreaded TreadMarks programs are within 7–30% of the MPI versions. 相似文献
98.
Dams R Murphy CM Choo RE Lambert WE De Leenheer AP Huestis MA 《Analytical chemistry》2003,75(4):798-804
A quantitative LC-APCI-MS/MS method for simultaneous determination of multiple illicit drugs, methadone, and their metabolites in oral fluid was developed and validated. Sample pretreatment was limited to acetonitrile protein precipitation. LC separation was performed in 25.5 min, with a total analysis time of 35 min. Identification and quantitation were based on selected reaction monitoring. Calibration by linear regression analysis utilized deuterated internal standards and a weighing factor 1/x. Limits of detection and lower limits of quantitation (LOQ) were established between 0.25 and 5 ng/ mL and 0.5-10 ng/mL, respectively. linearity was obtained with an average correlation coefficient (R2) of >0.99, over a dynamic range from the LOQ up to maximum 500 ng/mL The method demonstrated good accuracy, intra- and interbatch precision, recovery, and stability for all compounds. No oral fluid matrix effect was observed throughout the chromatographic run. Protein precipitation provided a fast and simple sample pretreatment, while LC-APCI-MS/MS proved to be a sensitive and rugged quantitative method for multiple illicit and legal drugs in oral fluid. The method proved to be suitable for the evaluation of oral fluid as an alternative matrix to urine for monitoring illicit drug use and for determining oral fluid methadone concentrations in pregnant opiate and/or cocaine addicts. 相似文献
99.
Honghui Lu Sandhya Dwarkadas Alan L. Cox Willy Zwaenepoel 《Journal of Parallel and Distributed Computing》1997,43(2):932
This paper compares two systems for parallel programming on networks of workstations: Parallel Virtual Machine (PVM), a message-passing system, and TreadMarks, a software distributed shared-memory (DSM) system. The eight applications used in this comparison are Water and Barnes–Hut from the SPLASH benchmark suite; 3-D FFT, Integer Sort (IS), and Embarrassingly Parallel (EP) from the NAS benchmarks; ILINK, a widely used genetic linkage analysis program; and Successive Over-Relaxation (SOR) and Traveling Salesman (TSP). Two different input data sets are used for five of the applications. We use two execution environments. The first is a 155 Mbps ATM network with eight Sparc-20 model 61 workstations; the second is an eight-processor IBM SP/2. The differences in speedup between TreadMarks and PVM depend mostly on the applications, and only to a much lesser extent on the platform and the data set used. In particular, the TreadMarks speedup for six of the eight applications is within 15% of that achieved with PVM. For one application, the difference in speedup is between 15% and 30%, and for another, the difference is around 50%. We identified four important factors that contribute to the lower performance of TreadMarks: (1) extra messages due to the separation of synchronization and data transfer, (2) extra messages to handle access misses caused by the use of an invalidate protocol, (3) false sharing, and (4) diff accumulation for migratory data. We have quantified the effects of the last three factors by measuring the performance gain when each is eliminated. Of the three factors, TreadMarks' use of a separate request message per page of data accessed is the most important. The effect of false sharing is comparatively low. Reducing diff accumulation benefits migratory data only when the diffs completely overlap. When these performance impediments are removed, all of the TreadMarks programs perform within 25% of PVM, and for six out of eight experiments, TreadMarks is less than 5% slower than PVM. 相似文献
100.
The objective of this paper is to check the efficiency and validity oftwo approaches for computing derivatives of complex functions,automatic differentiation using ADOLC and symbolicdifferentiation using MACSYMA. This has been done in three benchmarkexamples, where the gradient of a Helmholtz energy function has beencomputed for different dimensions of independent variables (Example 1)and Jacobian matrices of inverse kinematics of planar and spatialparallel robots (Examples 2 and 3) have been computed. The results havebeen evaluated under six criteria: preliminary implementation work,computation time, flexibility in applications, limits of applicability,accuracy, and memory requirements.ADOLC was superior to MACSYMA concerning preliminarywork (programming, source code generation, and compilation) andmodifications of the functions to be differentiated and thedifferentiation task to be performed. In addition, contrary toMACSYMA, no limits of applicability were observed forADOLC, even in the simulation of complex multi-body systems.On the other hand, for ADOLC the computation time of derivatives was 10 to 40 times higher than for MACSYMA. As aconsequence, differentiation by MACSYMA is better suited forreal-time applications like hardware in the loop simulation, real-timecontrol and real-time data processing than ADOLC.Both programs provide numerical results of equal accuracy. 相似文献