Multivariable Repetitive-predictive Controllers using Frequency Decomposition

Repetitive control is a methodology for the tracking of a periodic reference signal. This paper develops a new approach to repetitive control systems design using receding horizon control with frequency decomposition of the reference signal. Moreover, design and implementation issues for this form of repetitive predictive control are investigated from the perspectives of controller complexity and the effects of measurement noise. The analysis is supported by a simulation study on a multi-input multi-output robot arm where the model has been constructed from measured frequency response data, and experimental results from application to an industrial AC motor

Experimental study of oscillating SD8020 foil for propulsion

The thrust producing performance and efficiency of an SD8020 oscillating foil with a symmetrical saw-tooth angle of attack pitching profile was studied through force and torque measurements, as well as dye flow visualization, in the water tunnel at low Reynolds number of 13,000-16,000. The propulsive efficiency and thrust coefficient of the pitching foil were determined as a function of the Strouhal number, pitch amplitude and angular frequency. A propulsive efficiency of 30% was obtained experimentally at low Strouhal numbers. The flow visualization has revealed different wake patterns at various Strouhal numbers and can be classified into three regimes – a drag wake, a transition wake and a thrust wake. The drag wake consists of a combination of a regular Kármán street and an array of ‘primary’ stop-start vortices, whereas the thrust wake consists of a reverse Kármán vortex street, commonly observed in swimming fish. The transition wake regime, which occurs at approximately 0.2 < St < 0.5, is interpreted as a momentum balanced wake, where the thrust developed by the foil approximately balances its produced drag. This wake was observed to either consist of an inclined vortex street, or a paired vortex pattern. Based on the force and efficiency data collected, increasing pitch amplitude and angular frequency was associated with a decrease in propulsive efficiency and an increase in thrust forces produced. A high efficiency value of 0.3, accompanied by a thrust coefficient of order one is found at a low pitch amplitude of 10°, angular frequency of 0.79 rad/s and Strouhal number of 0.05. This presented the best conditions for thrust production observed at low Strouhal and Reynolds numbers

Growing Perfect Decagonal Quasicrystals by Local Rules

A local growth algorithm for a decagonal quasicrystal is presented. We show that a perfect Penrose tiling (PPT) layer can be grown on a decapod tiling layer by a three dimensional (3D) local rule growth. Once a PPT layer begins to form on the upper layer, successive 2D PPT layers can be added on top resulting in a perfect decagonal quasicrystalline structure in bulk with a point defect only on the bottom surface layer. Our growth rule shows that an ideal quasicrystal structure can be constructed by a local growth algorithm in 3D, contrary to the necessity of non-local information for a 2D PPT growth.Comment: 4pages, 2figure

An optical study of interdiffusion in ZnSe/ZnCdSe

Copyright 1996 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Applied Physics Letters 69, 1579 (1996) and may be found at

The Effect of the Disorder on the Longitudinal Resistance of a Graphene p-n Junction in Quantum Hall Regime

The longitudinal resistances of a six-terminal graphene p-n junction under a perpendicular magnetic field are investigated. Because of the chirality of the Hall edge states, the longitudinal resistances on top and bottom edges of the graphene ribbon are not equal. In the presence of suitable disorder, the top-edge and bottom-edge resistances well show the plateau structures in the both unipolar and bipolar regimes and the plateau values are determined by the Landau filling factors only. These plateau structures are in excellent agreement with the recent experiment. For the unipolar junction, the resistance plateaus emerge in the absence of impurity and they are destroyed by strong disorder. But for the bipolar junction, the resistances are very large without the plateau structures in the clean junction. The disorder can strongly reduce the resistances and leads the formation of the resistance plateaus, due to the mixture of the Hall edge states in virtue of the disorder. In addition, the size effect of the junction on the resistances is studied and some extra resistance plateaus are found in the long graphene junction case. This is explained by the fact that only part of the edge states participate in the full mixing.Comment: 7 pages, 5 figure

Integral Grothendieck-Riemann-Roch theorem

We show that, in characteristic zero, the obvious integral version of the Grothendieck-Riemann-Roch formula obtained by clearing the denominators of the Todd and Chern characters is true (without having to divide the Chow groups by their torsion subgroups). The proof introduces an alternative to Grothendieck's strategy: we use resolution of singularities and the weak factorization theorem for birational maps.Comment: 24 page

Anti-oxidative, metal chelating and radical scavenging effects of protein hydrolysates from blue-spotted stingray

Purpose: To evaluate protein hydrolysates and membrane ultrafiltration fractions of blue-spotted stingray for metal chelating and radical scavenging activities, as well as protection against oxidative protein damage.Methods: Stingray protein isolates were hydrolysed with alcalase, papain and trypsin for 3 h. Alcalase hydrolysate was fractionated by membrane ultrafiltration to yield &lt; 3, 3 - 10 and &gt; 10 kDa fractions. Peptide contents, iron and copper chelating activity, 2, 2'-azino-bis(3- ethylbenzothiazoline-6-sulphonic acid) (ABTS) and hydroxyl radical scavenging activities, and protection against oxidative protein damage were evaluated.Results: Three-hour alcalase hydrolysate (3AH) had the highest peptide content and the lowest half maximal effective concentration (EC50) for ABTS radical scavenging (793.9 μg/mL), hydroxyl radical scavenging (6.93 mg/mL), iron chelating (116.4 μg/mL) and copper chelating  activity (2136.9 μg/mL) among the hydrolysates. Among the fractions of 3AH, &lt; 3 kDa fraction had the best iron chelating activity, 3 - 10 kDa fraction exhibited the highest ABTS radical scavenging activity, while &gt; 10 kDa fraction showed the best copper chelating activity. The &lt; 3 kDa and 3 - 10 kDa fractions had similar levels of hydroxyl radical scavenging activity to reduced glutathione. The protective effects of 3AH and &lt; 3 kDa fraction against oxidative protein damage were comparable to that of reduced glutathione.Conclusion: Alcalase is the best protease for producing hydrolysates with metal chelating and antioxidant activities from stingray proteins. Alcalase hydrolysate, specifically its &lt; 3 kDa fraction, has potential for future applications in antioxidant therapy and health food formulation

Review on deployable structure

n construction industries, deployable structure has the capability to transform the structures components into predetermined configurations, safe and designated final known direction to achieve their architectural function. This construction technique provides ease of transportation and erection, more space and rapid completion time. This review aims to provide an overview of current potential deployable structure and system towards prefabrication modular construction application to overcome space and transportation limitation. This paper reviews the principle, application, characteristics, types and classification and design consideration of the deployable structures. Based on the literature reviewed, the deployable structure with simple folding configuration principle in linear direction is practical in application. Beside, the strength and stiffness of deployable structure depends on the proper design, material quality, elements thickness, dimension, joint rigidity and deployment technology. However, shape and direction of movement for deployable structure elements need to be determined in the initial stage to minimize the design failure. The findings from this review will contribute to the transformation of prefab volumetric construction practice to solve the limited space and transportation constraints issues