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51.
A fault-tolerant communications switch prototype supporting the packet switching communications paradigm has been implemented. The special feature of this switch is that it incorporates a modified version of the grouped adaptive function, found in the Inmos IMS C104 switch, which can logically group both consecutively and non-consecutively numbered links. 相似文献
52.
T. H. Ang F. S. A. Sultana D. W. Hutmacher Y. S. Wong J. Y. H. Fuh X. M. Mo H. T. Loh E. Burdet S. H. Teoh 《Materials science & engineering. C, Materials for biological applications》2002,20(1-2):35-42
A new robotic desktop rapid prototyping (RP) system was designed to fabricate scaffolds for tissue engineering applications. The experimental setup consists of a computer-guided desktop robot and a one-component pneumatic dispenser. The dispensing material (chitosan and chitosan–hydroxyapatite (HA) dissolved in acetic acid) was stored in a 30-ml barrel and forced out through a small Teflon-lined nozzle into a dispensing medium (sodium hydroxide–ethanol in ratio of 7:3). Layer-by-layer, the chitosan was fabricated with a preprogramed lay-down pattern. Neutralization of the chitosan forms a gel-like precipitate, and the hydrostatic pressure in the sodium hydroxide (NaOH) solution keeps the cuboid scaffold in shape. Comparison of the freeze-dried scaffold to the wet one showed linear and volumetric shrinkage of about 31% and 62%, respectively. A good attachment between layers allowed the chitosan matrix to form a fully interconnected channel architecture. Results of in vitro cell culture studies revealed the scaffold biocompatibility. The results of this preliminary study using the rapid prototyping robotic dispensing (RPBOD) system demonstrated its potential in fabricating three-dimensional (3D) scaffolds with regular and reproducible macropore architecture. 相似文献
53.
54.
Janarthanan Supramaniam Darren Yi Sern Low See Kiat Wong Loh Teng Hern Tan Bey Fen Leo Bey Hing Goh Dazylah Darji Fatimah Rubaizah Mohd Rasdi Kok Gan Chan Learn Han Lee Siah Ying Tang 《International journal of molecular sciences》2021,22(11)
Cellulose nanofibers (CNF) isolated from plant biomass have attracted considerable interests in polymer engineering. The limitations associated with CNF-based nanocomposites are often linked to the time-consuming preparation methods and lack of desired surface functionalities. Herein, we demonstrate the feasibility of preparing a multifunctional CNF-zinc oxide (CNF-ZnO) nanocomposite with dual antibacterial and reinforcing properties via a facile and efficient ultrasound route. We characterized and examined the antibacterial and mechanical reinforcement performances of our ultrasonically induced nanocomposite. Based on our electron microscopy analyses, the ZnO deposited onto the nanofibrous network had a flake-like morphology with particle sizes ranging between 21 to 34 nm. pH levels between 8–10 led to the formation of ultrafine ZnO particles with a uniform size distribution. The resultant CNF-ZnO composite showed improved thermal stability compared to pure CNF. The composite showed potent inhibitory activities against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative Salmonella typhi (S. typhi) bacteria. A CNF-ZnO-reinforced natural rubber (NR/CNF-ZnO) composite film, which was produced via latex mixing and casting methods, exhibited up to 42% improvement in tensile strength compared with the neat NR. The findings of this study suggest that ultrasonically-synthesized palm CNF-ZnO nanocomposites could find potential applications in the biomedical field and in the development of high strength rubber composites. 相似文献
55.
This letter integrates the tracking robustness of two-degrees-of-freedom control and fast dynamic response of flux-based, pulse-width modulation to develop a new current controller for high performance, three-phase electronic converter control. Theoretical analysis shows that the controller can simultaneously achieve good steady-state, transient and harmonic performance, which are challenges not previously met by existing current controllers reported in the literature. Experimental results are presented to verify the performance and practicality of the proposed controller. 相似文献
56.
Potential substitutes of natural gas and lignite fly ash as NO and HCN reducing agents, respectively, for heterogeneous reburning were examined in a bench-scale apparatus equipped with a simulated reburning and a burnout furnace. Selection of NO reducing agent is based on fuel volatility and nitrogen functionality. HCN reducing agent selection is based on literature data. A wide range of waste materials and industrial by-products show overall NO reduction efficiency up to 88% at reburning stoichiometric ratio 0.90 or 0.95. Mixed fuel containing scrap tire and Fe2O3 is particularly effective. Though its cost is constrained by the energy-intensive operation of grinding the tire, the estimated raw-material cost is better than that of natural gas reburning and highly competitive against SCR. A first-level approximation study of the selectivities of nitrogen species to form NO in burnout zone reveals the importance of HCN and char nitrogen reaction mechanisms. 相似文献
57.
Two novel coordination polymers [Zn2(tib)(chda)Cl2] (1) and [Zn(tib)I]I (2) have been prepared by reactions of 1,3,5-tris(1-imidazolyl)benzene (tib) and 1,2-cyclohexanedicarboxylic acid (H2chda) with corresponding Zn(II) salts, respectively. Complex 1 has a three-dimensional (3D) structure with rare gra (graphite) topology, while 2 is a typical two-dimensional (2D) (4·82) network. The results revealed that the counteranion plays a subtle and important role in the assembly procedure. Photoluminescent property of the complexes was investigated. 相似文献
58.
Hongjun Liu Wei Feng Choon Wee Kee Dasheng Leow Wei‐Tian Loh Choon‐Hong Tan 《Advanced Synthesis \u0026amp; Catalysis》2010,352(18):3373-3379
An efficient synthesis of oxacycles and azacycles was developed using a Brønsted base‐catalyzed tandem alkyne isomerization–Michael reaction sequence. Functionalized 2‐alkylidenetetrahydrofurans were prepared by an intramolecular oxy‐Michael reaction on an allene that was generated in situ from an alkynoate. The aza‐Michael version using alkynylamines, alkynylamides and alkynyl carbamates led to piperidines, lactams and oxazolidinones, respectively. An enantioselective version of this reaction resulted in an axially chiral lactam with high enantioselectivity. Some alkynes, however, were unable to complete the intramolecular Michael reactions and provided enantioenriched allenes. 相似文献
59.
Adaptation in the presence of a general nonlinear parameterization:an error model approach 总被引:1,自引:0,他引:1
Ai-Poh Loh Annaswamy A.M. Skantze F.P. 《Automatic Control, IEEE Transactions on》1999,44(9):1634-1652
Parametric uncertainties in adaptive estimation and control have been dealt with, by and large, in the context of linear parameterizations. Algorithms based on the gradient descent method either lead to instability or inaccurate performance when the unknown parameters occur nonlinearly. Complex dynamic models are bound to include nonlinear parameterizations which necessitate the need for new adaptation algorithms that behave in a stable and accurate manner. The authors introduce, in this paper, an error model approach to establish these algorithms and their global stability and convergence properties. A number of applications of this error model in adaptive estimation and control are included, in each of which the new algorithm is shown to result in global boundedness. Simulation results are presented which complement the authors' theoretical derivations 相似文献
60.
The Universal Mobile Telecommunications System (UMTS) offers IP-based multimedia applications and services with end-to-end Quality of Service (QoS) guarantee. The key component providing these services is the IP Multimedia Subsystem (IMS) that uses Service-Based Local Policy (SBLP) management for QoS control. To support end-to-end QoS, the UMTS IMS network should be scalable, reliable and flexible in policy deployment and enforcement, characteristics that are not found in single-domain policy architecture. A hybrid policy architecture is proposed, in which a hierarchical architecture is applied to the multi-domain environment in a single operator UMTS IMS network, while a peering architecture is employed in a multi-operator UMTS IMS network. The proposed multi-domain policy architecture potentially minimizes the session setup delay and policy exchange traffic while maximizing network scalability. 相似文献