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排序方式: 共有427条查询结果,搜索用时 15 毫秒
21.
L. C. Kwek E. K. Wong C. K. Loo M. V. C. Rao 《Journal of Intelligent and Robotic Systems》2003,37(2):143-162
This paper investigates the efficacy of the implementation of the conventional Proportional-Derivative (PD) controller and different Active Force Control (AFC) strategies to a 5-link biped robot through a series of simulation studies. The performance of the biped system is evaluated by making the biped walk on a horizontal flat surface, in which the locomotion is constrained within the sagittal plane. Initially, a classical PD controller has been used to control the biped robot. Then, a disturbance elimination method called Active Force Control (AFC) schemes has been incorporated. The effectiveness and robustness of the AFC as disturbance rejecter has been examined when a conventional crude approximation (AFCCA), and an intelligent active force control scheme, which is known as Active Force Control and Iterative Learning (AFCAIL) are employed. It is found that for both of the AFC control schemes proposed, the system is robust and stable even under the influence of disturbances. An attractive feature of the AFCAIL scheme is that inertia matrix tuning becomes much easier and automatic without any degradation in the performance. 相似文献
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23.
Jun Fang Shao-Wen Cao Zheng Wang Mohammad Mehdi Shahjamali Say Chye Joachim Loo James Barber Can Xue 《International Journal of Hydrogen Energy》2012
The mesoporous Au–TiO2 nanocomposites with different Au concentrations were prepared via a co-polymer assisted sol–gel method. The structures have been characterized by powder X-Ray diffraction, N2 adsorption–desorption isotherms, diffuse reflectance UV–Vis spectroscopy, X-ray photoemission spectroscopy, transmission electron microscopy. Most generated Au nanoparticles were embedded in the mesoporous TiO2 matrix. The prepared Au–TiO2 nanocomposites exhibit remarkable visible-light activity for H2 evolution from photocatalytic water reduction in the presence of ascorbic acid as the electron donor. By comparing with Pt–TiO2 samples, we found that the visible-light activity of the Au–TiO2 nanocomposites could be partially contributed by the defects/impurity states in the TiO2 matrix, while the gold surface plasmons could significantly enhance the weak visible-light excitation of TiO2 matrix. In addition, further studies by controlling irradiation wavelengths suggest that some plasmon-excited electrons could transfer from Au nanoparticles to the contacting TiO2 to reduce water for H2 generation. We believe that these Au–TiO2 nanocomposites as well as the mechanistic studies would have considerable impact on future development of metal-semiconductor hybrid photocatalysts for efficient solar hydrogen production. 相似文献
24.
R. Bilyalov L. Stalmans G. Beaucarne R. Loo M. Caymax J. Poortmans J. Nijs 《Solar Energy Materials & Solar Cells》2001,65(1-4)
The potential of porous silicon (PS) with dual porosity structure as an intermediate layer for ultra-thin film solar cells is described. It is shown that a double-layered PS with a porosity of
% allows to grow epitaxial Si film at medium temperature (725°–800°C) and at the same time serves as a gettering/diffusion barrier for impurities from potentially contaminated low-cost substrate. A 3.5 μm thin-film cell with reasonable efficiency is realized using such a PS intermediate layer. 相似文献
25.
Loo L Capobianco JA Wu W Gao X Shih WY Shih WH Pourrezaei K Robinson MK Adams GP 《Analytical chemistry》2011,83(9):3392-3397
Rapid and sensitive detection of serum tumor biomarkers are needed to monitor cancer patients for disease progression. Highly sensitive piezoelectric microcantilever sensors (PEMS) offer an attractive tool for biomarker detection; however, their utility in the complex environment encountered in serum has yet to be determined. As a proof of concept, we have functionalized PEMS with antibodies that specifically bind to HER2, a biomarker (antigen) that is commonly overexpressed in the blood of breast cancer patients. The function and sensitivity of these anti-HER2 PEMS biosensors was initially assessed using recombinant HER2 spiked into human serum. Their ability to detect native HER2 present in the serum of breast cancer patients was then determined. We have found that the anti-HER2 PEMS were able to accurately detect both recombinant and naturally occurring HER2 at clinically relevant levels (>2 ng/mL). This indicates that PEMS-based biosensors provide a potentially effective tool for biomarker detection. 相似文献
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Rocío Mato-Basalo Miriam Morente-Lpez Onno J Arntz Fons A. J. van de Loo Juan Fafin-Labora María C. Arufe 《International journal of molecular sciences》2021,22(7)
Mesenchymal stem cells have an important potential in the treatment of age-related diseases. In the last years, small extracellular vesicles derived from these stem cells have been proposed as cell-free therapies. Cellular senescence and proinflammatory activation are involved in the loss of therapeutic capacity and in the phenomenon called inflamm-aging. The regulators of these two biological processes in mesenchymal stem cells are not well-known. In this study, we found that p65 is activated during cellular senescence and inflammatory activation in human umbilical cord-derived mesenchymal stem cell. To demonstrate the central role of p65 in these two processes, we used small-molecular inhibitors of p65, such as JSH-23, MG-132 and curcumin. We found that the inhibition of p65 prevents the cellular senescence phenotype in human umbilical cord-derived mesenchymal stem cells. Besides, p65 inhibition produced the inactivation of proinflammatory molecules as components of a senescence-associated secretory phenotype (SASP) (interleukin-6 and interleukin-8 (IL-6 and IL-8)). Additionally, we found that the inhibition of p65 prevents the transmission of paracrine senescence between mesenchymal stem cells and the proinflammatory message through small extracellular vesicles. Our work highlights the important role of p65 and its inhibition to restore the loss of functionality of small extracellular vesicles from senescent mesenchymal stem cells and their inflamm-aging signature. 相似文献
28.
S. Ramesh Z.Z. Loo C.Y. Tan W.J. Kelvin Chew Y.C. Ching F. Tarlochan Hari Chandran S. Krishnasamy L.T. Bang Ahmed A.D. Sarhan 《Ceramics International》2018,44(9):10525-10530
In this work, the viability of producing biogenic hydroxyapatite from bio-waste animal bones, namely bovine (cow), caprine (goat) and galline (chicken), through a heat treatment process has been investigated. The animal bones were locally sourced, cleaned to remove collagen and subsequently heat treated in air atmosphere at different temperatures ranging from 600?°C to 1000?°C. From the range of sintering temperatures investigated, it was found that hydroxyapatite derived from bovine bone showed good thermal stability while those produced from caprine and galline bones exhibited phase instability with traces of tri-calcium phosphate (TCP) being detected after heat treatment beyond 700?°C. The porous nature of the bone samples can be observed from the microstructures obtained and supported by low relative density. Heating the bovine and caprine bones at selected temperatures yielded porous HA body, having hardness values that are comparable with human cortical bone. However, the sintered galline bone sample showed higher porosity levels and low hardness when compared to the other two bone types. 相似文献
29.
This study explores empirical relationships among different types of pinches in three age groups. Peak maximum voluntary forces of several pinches--lateral, chuck, and pulp pinches with digits 2, 3, 4, and 5-were tested in 182 subjects comprising 62 children (5-12 years), 70 adults (18-40 years), and 50 elderly (60-89 years). Analysis of the forces indicated four groups of strength magnitude: (1) lateral and chuck, (2) pulp 2 and 3, (3) pulp 4, and (4) pulp 5, in that order; the strength of each type of pinch bears a definite quantitative relationship to every other type, regardless of age group or gender. The female-to-male strength ratio was greatest in children (89%) and least in adults (69%). Comparison with other pinch strength studies established that although force magnitudes may be strongly influenced by specific experimental conditions, empirical relationships among different pinch forces are fairly stable and predictable. 相似文献
30.