Self-powered active lateral suspension for railway vehicles

This paper presents a design methodology for the development of self-powered active lateral secondary suspensions for rail vehicles. It firstly investigates the energy flows in the active lateral secondary suspensions and analyzes the conditions for self-powered control in detail. The impact of the controller design on both the ride quality and the energy consumption is then used to guide the design/specification of actuators and to define key actuator parameters in order to achieve both expected performance improvement and zero-energy consumption for the actuators. Furthermore, a control strategy for dealing with larger than expected energy consumptions by the active suspensions is proposed to eliminate excessive power requirements, but also to ensure the ride quality improvement in comparison to that of passive suspensions. Computer simulations are used to validate the control strategy for the self-powered active suspension

Genetic and phylogenetic analysis of ten Gobiidae species in China based on amplified fragment length polymorphism (AFLP) analysis

To study the genetic and phylogenetic relationship of gobioid fishes in China, the representatives of 10 gobioid fishes from 2 subfamilies in China were examined by amplified fragment length polymorphism (AFLP) analysis. We established 220 AFLP bands for 45 individuals from the 10 species, and the percentage of polymorphic bands was 100%. The percentage of polymorphic loci within species ranged from 3.61 to 58.56%. Chaeturichthys stigmatias showed the greatest percentage of polymorphic loci (58.56%), the highest Nei’s genetic diversity (0.2421 ± 0.2190) and Shannon’s information index (0.3506 ± 0.3092), while Pterogobius zacalles showed the lowest percentage polymorphic loci (3.61%), the lowest Nei’s genetic diversity (0.0150 ± 0.0778) and lowest Shannon’s information index (0.0219 ± 0.1136). The topology of UPGMA tree showed that the individuals from the same species clustered together and the 10 species formed two major clades. One clade consisted Cryptocentrus filifer, P. zacalles, Tridentiger trigonocephalus, Chaeturichthys hexanema, C. stigmatias, Acanthogobius flavimanus and Synechogobius ommaturus, and the other clade consisted Odontamblyopus rubicundus, Trypauchen vagina and Ctenotrypauchen microcephalus. The results agreed with the traditional taxonomy of the morphological characters. AFLP fingerprints were successfully used to study the phylogenetic relationship of the gobioid fishes and it identified species origins of morphologically similar taxa.Key words: Phylogenetic, amplified fragment length polymorphism (AFLP), gobiidae, Amblyopinae, gobiinae

Rotor-position detection in permanent-magnet wheel motor to ensure smooth startup from standstill

In this paper, an innovative rotor-position-detection method for a permanent-magnet wheel motor (PMWM) that operates from standstill to low speed is presented. The neutral voltage, which is sensed through phaseshifted pulse width modulation, overcomes the limitations of the conventional back electromotive force (EMF)-based position-detection method, which is more suitable for high-speed operation. In addition, a technique that ensures a transition between the two position-detection methods is presented to cover the full speed range. Computer simulations are employed to design and assess the neutral-voltage-based and EMF-based position-detection methods. The results of the position detection and angle error are presented starting from standstill to low speed. A step current (iq) corresponding to motor torque demand is applied for the starting process in the two position-detection methods. The experimental studies of the new position-detection method are conducted. The method is successfully applied to drive a 60-kW PMWM that operates from standstill to high speed. This demonstrates the effectiveness and performance of the presented method

Density functional theory studies of hydrogen bonding vibrations in sI gas hydrates

Abstract To analyze the vibrational modes of water and methane in structure I gas hydrates, we constructed a 178-atom supercell with two small cages of type 512 and six large cages of type 51262. We applied the density functional theory method to simulate the vibrational spectrum and normal modes of methane hydrates. In accord with our previous studies, we confirmed that two groups of hydrogen bond (H-bond) peaks (at around 291 and 210 cm−1) in the translational bands come from two kinds of intermolecular H-bond vibrational modes. This is the first investigation of H-bond vibrations in methane hydrates. The partial modes of CH4 were extracted. We found that the CH4 phonons in the translational region are below 180 cm−1 so that the influence of methane on the H-bond is insignificant. We proposed a new method to decompose gas hydrates via direct application of terahertz radiation to the H-bonds. Herein, we confirmed that CH4 molecules do not absorb this energy.</jats:p

Formation of sp³ bonding in nanoindented carbon nanotubes and graphite

Author name used in this publication: C. H. Woo2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A Condensation-Ordering Mechanism in Nanoparticle-Catalyzed Peptide Aggregation

Nanoparticles introduced in living cells are capable of strongly promoting the aggregation of peptides and proteins. We use here molecular dynamics simulations to characterise in detail the process by which nanoparticle surfaces catalyse the self- assembly of peptides into fibrillar structures. The simulation of a system of hundreds of peptides over the millisecond timescale enables us to show that the mechanism of aggregation involves a first phase in which small structurally disordered oligomers assemble onto the nanoparticle and a second phase in which they evolve into highly ordered beta-sheets as their size increases

Multi-Directional Growth of Aligned Carbon Nanotubes Over Catalyst Film Prepared by Atomic Layer Deposition

The structure of vertically aligned carbon nanotubes (CNTs) severely depends on the properties of pre-prepared catalyst films. Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD) was employed to deposit uniform Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology. The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future