Design and Performance of Miniaturized Piezoelectric Step-Down Transformer

Piezoelectric transformers are expected to be small, thin and highly efficient, and which are attractive as a transformer with high power density for step down voltage. For these reasons, we have attempted to develop a step-down piezoelectric transformer for the miniaturized adaptor. we propose a piezoelectric transformer, operating in thickness extensional vibration mode for step-down voltage. This transformer consists of a multi-layered construction in the thickness direction. In order to develop the step-down piezoelectric transformers of 10 W class and turn ratio of 0.1 with high efficiency and miniaturization, the piezoelectric ceramics and piezoelectric transformer designs are estimated with a variety of characteristics. The basic composition of piezoelectric ceramics consists of ternary yPb(Zr_xTi_{1 – x})O₃–(1–y)Pb(Mn_1/3Nb_1/3Sb_1/3)O₃. In the piezoelectric characteristics evaluations, at y = 0.95 and x = 0.505, the electromechanical coupling factor(k_p) is 58%, piezoelectric strain constant (d₃₃) is 270 pC/N, mechanical quality factor(Q_m) is 1520, permittivity ( ₃₃^T/₀) is 1500, and Curie temperature is 350C. At y = 0.90 and x = 0.500, k_p is 56%, d₃₃ is 250 pC/N, Q_m is 1820, ₃₃^T/₀ is 1120, and Curie temperature is 290C. It shows the excellent properties at morphotropic phase boundary regions. PZT-PMNS ceramic may be available for high power piezoelectric devices such as piezoelectric transformers. The design of step-down piezoelectric transformers for adaptor proposes a multi-layer structure to overcome some structural defects of conventional piezoelectric transformers. In order to design piezoelectric transformers and analyze their performances, the finite element analysis and equivalent circuit analysis method are applied. The maximum peak of gain G as a first mode for thickness extensional vibration occurs near 0.85 MHz at load resistance of 10 . The peak of second mode at 1.7 MHz is 0.12 and the efficiency is 92%.     

Analysis of a clutch damper using a discrete model

It is important to have a precise model for the clutch damper in order to simulate the entire powertrain of a vehicle and predict the responses of the system. In this research, we developed a new model in which the spring used in the clutch damper is divided into a finite number of elements. The model takes many unique properties of arc-shaped springs into consideration and is anticipated to be more precise than conventional simple models. With the model, two meaningful results were presented which can be utilized afterwards. One is a simulation concerning the peak torque transmitted via the clutch damper. The other is a simulation that shows the hysteretic characteristics of the clutch damper.     

Using mass spectrometry to study copper-protein binding under native and non-native conditions: beta-2-microglobulin

A method based on metal-catalyzed oxidation (MCO) reactions and mass spectrometry (MS) has been used to determine the Cu(II) binding sites in both native and unfolded conformations of beta-2-microglobulin (beta2m). Recent studies have shown that beta2m is destabilized and can form amyloid fibers in the presence of Cu(II). An increased affinity for Cu in unfolded states compared to that of the native state is suspected to facilitate overall protein destabilization. Cu-binding site information for native beta2m is difficult to obtain using traditional techniques because of its propensity to form amyloid fibers at relatively high protein concentrations in the presence of Cu and because of the nonspecific paramagnetic peak broadening observed in NMR analyses. In addition, Cu-binding information of unfolded beta2m is complicated by the high concentrations of denaturants (e.g., 8 M urea) needed to ensure protein unfolding. The MCO/MS approach has been successfully employed in this work to overcome these difficulties. The sensitivity of MS allowed the Cu-binding site of the native protein to be determined at the low concentrations of beta2m necessary to avoid amyloid fiber formation. Results indicate that the N-terminus of the protein and His31 are responsible for Cu(II) coordination in the native state. The MCO/MS method was also successful at determining the Cu-binding site in the presence of 8 M urea with the N-terminus, His31, His51, and His81 found to be Cu-bound in the unfolded state. This result supports the existence of a well-defined but different coordination structure in the unfolded state, which leads to the greater affinity for Cu(II) observed in the unfolded state of the protein. In general, it appears that the MCO/MS method is capable of providing Cu-binding site information for proteins that are difficult to study by traditional means.     

Autostereoscopic three-dimensional display based on a micromirror array

A novel approach for three-dimensional (3-D) display systems implemented with a micromirror array was proposed, designed, realized, and tested. The major advantages of this approach include the following: (1) micromirrors are reflective and hence achromatic (panchromatic), (2) a wide variety of displays can be used as image sources, and (3) time multiplexing can be introduced on top of space multiplexing to optimize the viewing zone arrangements. A two-view (left and right) 3-D autostereoscopic display system was first constructed. Left- and right-eye views in the forms of both still and motion 3-D scenes were displayed, and viewers were able to fuse the stereo information. A multiview (two left and two right) 3-D autostereoscopic display system was then simulated.     

CAutoCSD – Evolutionary Search and Optimisation Enabled Computer Automated Control System Design

This paper attempts to set a unified scene for various linear time-invariant (LTI) control system design schemes, by transforming the existing concept of "computer-aided control system design" (CACSD) to novel "computer-automated control system design" (CAutoCSD). The first step towards this goal is to accommodate, under practical constraints, various design objectives that are desirable in both time and frequency domains. Such performance-prioritised unification is aimed at relieving practising engineers from having to select a particular control scheme and from sacrificing certain performance goals resulting from pre-commitment to such schemes. With recent progress in evolutionary computing based extra-numeric, multi-criterion search and optimisation techniques, such unification of LTI control schemes becomes feasible, analytical and practical, and the resultant designs can be creative. The techniques developed are applied to, and illustrated by, three design problems. The unified approach automatically provides an integrator for zero-steady state error in velocity control of a DC motor, and meets multiple objectives in the design of an LTI controller for a non-minimum phase plant and offers a high-performance LTI controller network for a non-linear chemical process.     

The three-dimensional structure of Arabidopsis thaliana O-methyltransferase predicted by homology-based modelling

O-methylation of flavonoid compounds is an important enzymatic reaction since it not only reduces the chemical reactivity of their phenolic hydroxyl groups but also increases their lipophilicity and, hence, their intracellular compartmentation. Several genes encoding flavonoid O-methyltransferases (OMTs) have been isolated and characterized both at the molecular and biochemical levels. In contrast with mammalian enzymes, plant OMTs exhibit narrow substrate specificities as well as position-specific activities, so that the homology comparison, derived using programs such as BLAST can not provide sufficient information on the enzyme function or its substrate preference. In order to study these characteristics, therefore, another approach, homology-based modelling is being carried out. We report here the determination of the 3-D structure of Arabidopsis thaliana O-methyltransferase, AtOMT1 as well as its dynamics when complexed with its substrate. The predicted structure obtained by homology-based modelling is conserved during molecular dynamics simulations. AtOMT1 exhibits a structure similar to that of caffeic acid O-methyltransferase, COMT when the latter was used as a template. Whereas COMT includes 20 alpha-helices and nine beta-sheets, AtOMT1 has 16 and 9, respectively. Although the homology between both proteins is higher than 77% and all amino acids surrounding the active sites, except one residue, are similar in their primary sequences, the two proteins exhibit different substrate preferences. The differences in substrate specificity may be explained on the basis of the predicted structures of the protein and its complex with the substrate. In addition, docking the substrate into the active site of the protein allowed the study of the structural change of the active site on the dihedral angle distribution of the residues surrounding the active site.     

Purification and properties of human N-acetylgalactosamine-6-sulfate sulfatase

1. Human N-acetylgalactosamine-6-sulfate sulfatase (EC 3.1.6.-) from human placenta has been purified more than 3000-fold by gel filtration, ion-exchange and substrate affinity chromatography. The enzyme has a molecular weight of 90 000 by gel filtration chromatography and 85 000 by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Enzyme purified from cultured human skin fibroblasts has similar properties. 2. The tritium-labeled chrondroitin 6-sulfate trisaccharide N-acetylgalactosamine 6-sulfate-(beta, 1-4)-glucuronic acid-(beta, 1-3(-N-acetyl[1-3H]galactosaminitol 6-sulfate as substrate demonstrated a Km of 0.12 mM at pH 4.5. Sulfate was hydrolyzed only from the non-reducing terminal of this disulfated trisaccharide. Hyaluronic acid, dermatan sulfate, chondroitin 4-sulfate, heparin and chondroitin 6-sulfate tetrasaccharide were slightly inhibitory, whereas 6-sulfated pentasaccharides and heptasaccharides were strongly inhibitory. The enzyme dose not hydrolyze sulfate from N-acetylglucosamine 6-sulfate.     

Non-Coherent Digital Matched Filters: Multibit Quantization

A study of non-coherent digital matched filters (DMF's) with multibit quantizers, matched to phase-shift-keyed signals, is presented. Results relating output and input signal-to-noise ratios are given for three types of additive channel interference and mixtures thereof: white Gaussian noise and incoherent and coherent constantamplitude sine-wave jamming. These results are compared with both analog filter results and computer simulation runs obtained previously.     

Identification of Certain Sultones as the Sensitizers in an Alkyl Ethoxy Sulfate

Skin sensitizing agents that were present in a specific batch of alkyl ethoxy sulfate (AES) were identified as 1-dodecene-1,3-sultone and 1-tetradecene-1,3-sultone. Two other sensitizing agents that were present in the AES were tentatively identified as 2-chloro-1,3-dodecanesultone and 2-chloro-1,3-tetradecanesultone. A route of formation for these sensitizers has been postulated which is consistent with the specific conditions used for the manufacture of this batch of AES.     

Scheduling and Transport for File Transfers on High-Speed Optical Circuits

Scheduling resources on Grids is a well-known problem. The extension of Grids to LambdaGrids requires the scheduling of lambdas, i.e., end-to-end high-speed circuits. In this paper, we propose a scheduling heuristic for such lambdas in support of large-scale scientific applications that require high-throughput transfers of large files. We refer to this heuristic as Varying-Bandwidth List Scheduling (VBLS) because the scheduler returns a Time-Range-Capacity (TRC) allocation vector with varying bandwidth levels assigned for different time ranges within the duration of a transfer. The advantage of VBLS over a fixed-bandwidth allocation scheme is that it allows the scheduler to backfill any holes left in resource allocations. Enabling VBLS requires end host applications to specify the file size in their transfer requests. To characterize VBLS, we ran simulation experiments that show that VBLS performance approaches packet-switching performance. This result means that file transfers can take advantage of bandwidth that becomes available subsequent to the start of transfers, a current and critical drawback of typical fixed-bandwidth allocation schemes in circuit-switched networks. Next, we identify the key features needed in a transport protocol that works in conjunction with VBLS and develop the Varying Bandwidth Transport Protocol (VBTP). VBTP is a rate based flow control scheme that is coupled with Selective-ARQ based error control. Finally, the paper concludes with a discussion on the impact of transport problems on VBLS scheduling.