Experimental investigation of feedforward control schemes of a flexible robot manipulator system

This paper presents experimental investigations into the applications of feedforward control schemes for vibration control of a flexible manipulator system. Feedforward control schemes based on input shaping and filtering techniques are to be examined. A constrained planar single-link flexible manipulator is considered in this experimental work. An unshaped bang-bang torque input is used to determine the characteristic parameters of the system for design and evaluation of the input shaping control techniques. The input shapers and filtering techniques are designed based on the properties of the system. Simulation results of the response of the manipulator to the shaped and filtered inputs are presented in time and frequency domains. Performances of the shapers are examined in terms of level of vibration reduction and time response specifications. The effects of derivative order of the input shaper on the performance of the system are investigated. Finally, a comparative assessment of the control strategies is presented and discusse

Decentralised distributed fountain coding: asymptotic analysis and design

A class of generic decentralised distributed fountain coding schemes is introduced and the tools of analysis of the performance of such schemes are presented. It is demonstrated that the developed approach can be used to formulate a robust code design methodology in a number of instances. We show that two non-standard applications of fountain codes, fountain codes for distributed source coding and fountain codes for unequal error protection lie within this decentralised distributed fountain coding framework

Incidence and significance of black aspergilli in agricultural commodities: a review, with a key to all species accepted to-date

Black aspergilli (Aspergillus species of Section Nigri) present dark colonies, often black, and uniseriate or biseriate conidial heads. Currently 26 species and one variety are accepted within this section. They have been isolated from a wide variety of food worldwide and are considered as common causes of food spoilage and biodeterioration of other materials. They are commonly present in cereals and vineyards and have the ability to cause Aspergillus rot of black berry. Some species of this section, like A. niger and A. awamori, are a common source of extracellular enzymes such as amylases and lipases, and organic acids, such as citric and gluconic acid, used as additives in food processing and are used for biotechnological purposes. These products hold the GRAS (Generally Recognised as Safe) status. Other species are able to produce ochratoxins (OTA) and fuminisins. This review briefly shedlighted on the taxonomy of this important group of Aspergillus along with the species incidence, mycotoxin production in agricultural commodities as well as their significance as plant pathogens. A provisional key for identification (based on phenotypic characteristics) is provided for all described species to-date

Development and performance evaluation of a natural draft mixed-type solar dryer for agricultural products

Reduced moisture content enhances storage properties of agricultural products and reduces post-harvest losses. Effective drying can be achieved using solar dryers in regions with abundant solar radiation. In this study, a natural draft mixed-type solar dryer suitable for rural communities of developing countries was developed. The performance of the solar dryer was also investigated using pepper, okra and tomato. The temperature taken at different points of the drying chamber and the auxiliary collector show that the temperature within the drying chamber is higher than the ambient temperature. The temperature within the drying chamber was also found to depend on the atmospheric conditions. The maximum drying rate was obtained at periods between 1200 and 1400 hrs Nigeria local time during which the temperature within the solar dryer is also maximum. Temperature within the solar dryer reached up to 62°C. The solar collector efficiency was 52.0% while the drying efficiency was 21.9%.Peer reviewe

Anomalous Chiral Fermi Surface

We provide a geometrical argument for the emergence of a Wess-Zumino-Witten (WZW) term for a Fermi surface threaded by a Berry curvature. In the presence of external fields, the gauged WZW term yields a chiral (triangle) anomaly for the fermionic current at the edge of the Fermi surface. Fermion number is conserved though since the Berry curvatures occur always in pairs with opposite (monopole) charge. The anomalous vector and axial currents for a a fermionic fluid at low temperature threaded by pairs of Berry curvatures are discussed. The leading temperature correction to the chiral vortical effect in a slowly rotating Fermi surface threaded by a Berry curvature maybe tied to the gravitational anomaly.Comment: 4 pages; version to appear in PR