Fluorescent background is a major problem in recoding the Raman spectra of many samples, which swamps or obscures the Raman signals. The background should be suppressed in order to perform further qualitative or quantitative analysis of the spectra. For this purpose, an intelligent background-correction algorithm is developed, which simulates manual background-correction procedure intelligently. It basically consists of three aspects: (1) accurate peak position detection in the Raman spectrum by continuous wavelet transform (CWT) with the Mexican Hat wavelet as the mother wavelet; (2) peak-width estimation by signal-to-noise ratio (SNR) enhancing derivative calculation based on CWT but with the Haar wavelet as the mother wavelet; and (3) background fitting using penalized least squares with binary masks. This algorithm does not require any preprocessing step for transforming the spectrum into the wavelet space and can suppress the fluorescent background of Raman spectra intelligently and validly. The algorithm is implemented in R language and available as open source software (http://code.google.com/p/baselinewavelet).

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The conjugated straight-line internal gear pair, including a pinion with straight-line profile and an internal gear with profile conjugated to the pinion profile, is the key components to the conjugated straight-line internal gear pumps. Truninger [ Truninger gear pump. Patent 3491698, USA, 1970] pointed that this kind of gear pairs leads to a very small trapped volume, which is 10 times smaller than that of the conventional involute internal gear pumps. Therefore, it can yield significant reduction in noise levels of the pumps. However, to the authors’ knowledge, there is no research on the design of these gear pairs until now. First, our study describes the straight-line profile of the pinion mathematically with definitions of some geometric parameters. Second, according to the theory of gearing, the mathematical models of the rack-cutter and the conjugated internal gear are derived. Then, the condition to avoid overcutting is obtained for the generation of the pinion by a rack-cutter. Finally, the condition to avoid interference in the internal gear pair is derived as a non-linear equation system and an algorithm is developed to find a numerical solution. Two examples are presented to demonstrate how to determine tooth numbers of the internal gears for avoiding interference. It is hoped that the study in this article should be helpful to the designers of the conjugated straight-line internal gear pairs. Moreover, it could provide a prepared knowledge for the researchers to investigate the performances of the fluid power gear machines, pumps, and motors, with the conjugated straight-line internal gear pumps.

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A mathematical model has been presented for a high speed liquid jet penetration into soft solid by a needle-free injection system. The model consists of a cylindrical column formed by the initial jet penetration and an expansion sphere due to continuous deposition of the liquid. By solving the equations of energy conservation and volume conservation, the penetration depth and the radius of the expansion sphere can be predicted. As an example, the calculation results were presented for a typical needle-free injection system into which a silicon rubber was injected into. The calculation results were compared with the experimental results.

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The catalytic properties of catalysts are generally highly dependent on their nanostructures in most heterogeneous catalytic reactions. Therefore, to acquire targeted catalytic activity, selectivity, and stability, catalysts with a specific nanostructure should be designed and synthesized. Herein, Ru‐Ni bimetallic nanoparticles with different nanostructures, Ru‐Ni alloy, Ru@Ni, and Ru clusters‐on‐Ni on carbon, have been synthesized by annealing Ru‐Ni/C in flowing N2+10 % H2 at different temperatures. The various nanostructures of the Ru‐Ni bimetallic nanoparticles have been characterized and their catalytic behaviors were evaluated using benzene hydrogenation to cyclohexane. The relationship between the Ru‐Ni bimetallic nanostructures and their catalytic performance is presented. It was found that Ru‐Ni alloy/C and Ru clusters‐on‐Ni/C are much more active than Ru@Ni/C. This study also provides a simple method to design and control the nanostructures of the Ru‐Ni bimetallic nanoparticles.