Biological Insights Into Robotics: Honeybee Foraging Behavior by a Waggle Dance

A honeybee informs her nestmates of flower locations by a unique behavior called a 'waggle dance'. We regard this behavior as a good model of the 'propagation and sharing of knowledge' to maintain a society. We have attempted to reveal how this dance benefits the colony using mathematical models and computer simulation based on parameters obtained from observations of bee behavior. Our simulation indicated that the most successful forages were made by a putative bee colony that used the dance to communicate. Video analysis of worker honeybee behavior in the field showed that a bee does not dance in a single, random place in the hive, but waggles several times in one place and several times in another. The orientation and duration of waggle runs varied from run to run, within ranges of ±15° and ±15%, respectively. We also found that most of the bees that listened to the waggle dance turned away from the dancer after listening to one or two runs. These data suggest that honeybees use the waggle dance as a method of communication, but that they must base their forages on ambiguous information about the location of a food source.     

12—THEORETICAL CONSIDERATIONS IN OPEN-END SPINNING

Two problems are discussed in this paper. In the first, the effect of the deposition of fibres in open-end-spinning systems on the yarn irregularity produced is considered.

The drafting operations are divided into two types, that is, System I and System II. System I is the type in which fibres are accelerated when the leading ends arrive at a point or a specified area, and System II is the type in which the trailing ends are accelerated in the same way as those of System I. System II is more profitable if the fibres have non-uniform length, and the leading-fibre-end-density function contains most of the irregularity. The rotating-drum spinning method is also considered from the viewpoint of yarn irregularity, and the range of wavelengths that should be decreased by this method is calculated. The conclusion is that the total draft must be smaller than 2πR/[lbar], where R is the inner radius of the drum and [lbar] is the mean fibre length.

The second problem concerns the separation draft. Open-end drafting systems require very high drafts for separating the fibres. The problem is to determine what value of draft is needed. The conclusion reached is that perfect separation is impossible because of the random arrangement of fibres. The probability of separation is presented and calculated theoretically.     

Optimal configuration of blast furnace slag runner to reduce fluid flow stresses at wall using mathematical modelling

Abstract

A three-dimensional mathematical model was developed to predict the wall shear stresses due to flow of liquid slag in slag runner of 'G' blast furnace of Tata Steel under different conditions. The liquid slag flow in the slag runner was considered to be turbulent and incompressible. The model was developed for single phase, steady state and isothermal conditions. To this end, the Navier Stokes equations along with continuity and turbulence equations (standard k–? model) were simultaneously solved with appropriate boundary conditions at the associated physical boundaries of the calculation domain. Several configurations were numerically assessed with respect to reduced shear stresses on the wall of the slag runner to select the best one. Due to accelerating flow the operating heights of liquid slag (density 2800 kg m^–3 at 1500°C) within the slag runner for different configurations were estimated with the help of Bernoulli's and continuity equations and fixed before the computation. The different configurations comprised of three segments with different parameters of either elevation or radius of curvature. Relatively high shear stresses were numerically predicted at the joint area of second and third segments of the slag runner for all the configurations. The radius of curvature was found as the dominant factor to reduce the shear stress at the joint region.     

41—THE RETRACTION AND STRETCH OF WRAPPED ELASTOMERIC-FIBRE CORE YARNS

Equations are given that relate the structure of spirally wrapped elastomeric-fibre core yams to their stretch properties. The model employed improves upon previous ones by considering the effect of covering-yarn diameter. Graphs are given that facilitate the use of the theory for manufacturing purposes.

A comparison with available experimental data indicates an improved agreement between actual and predicted values of retraction in the most important case, where the input and output yarn lengths are measured. It is expected that the improved theory given here will show to much greater advantage with the present commercial fine-core wrapped structures.

In the special case where the wrapping or covering yarns have very low twist, the basic theory is inadequate. Modifications to account for compression of the cover yarn are accordingly included to enable an approximate relationship between yarn structure and stretch to be obtained in this case.     

Design of single element flow control device in twin strand billet tundish for continuous casting of steel using flow simulation model

Abstract

An optimal single element flow control device (SEFCD) is proposed in the present study for a small capacity twin strand tundish, to produce steel billet with the desired cleanliness, designed by means of numerical experimentation. To achieve this goal, a mathematical model based on the SOLA-SURF technique and the k-? (where k is the kinetic energy of the fluid and ? is its dissipation) two equation turbulence model has been developed to simulate the fluid flow phenomena of molten steel, as well as the mass transfer phenomena of tracer during steady state operation in the tundish. The accuracy of the mathematical model has also been verified by water model experiments, which indicate that the mathematical model is sufficiently accurate and suitable as a tool to develop an optimal SEFCD as required in the present study. Several SEFCD designs have then been evaluated using the mathematical model. The simulated results show that a billet tundish with a high, long, trough shaped pouring pad arrangement has the highest residence time, which promotes inclusion removal, and is thus considered the optimal SEFCD design for the billet tundish.     

Electrodeposition,characterisation and mathematical model of nickel–iron film in a parallel plate flow system

Abstract

Nickel–Iron alloy films were electrodeposited in a parallel plate flow system. The volumetric flow rate of electrolyte was fixed at 12 dm³ min^?1 through the 1 cm thick and 9 cm wide slit parallel plate. Fluid velocity was ca 0.22 m s^?1 under fully turbulent convective flow. Alloy films with iron content varying from 7·5 to 40 wt-% were deposited as a function of solution pH, temperature, bath ingredient concentration and applied current density. It is shown that the magnetic property is strongly correlated to the alloy content: the saturation moment, B _s, increases with the iron composition, while the coercivity, H _c, increases with nickel content. Current efficiency increases with pH and applied current density. The nickel deposition rate is inhibited in the presence of ferrous ion in the plating bath. The microhardness of the deposit is increased as the iron content is increased over the range studied. A mathematical model that considers the convective mass transfer of Fe(II) and Ni(II) species in the diffusion layer, the competition of adsorbed metal species on surface active sites, and Tafel electrochemical kinetics describe the alloy plating system well.     

Simulation of shape and temperature field evolution of solder joints during reflow solidification process

Abstract

A large proportion of research on soldered joints focuses on the effects of stress on the service life of a solder joint. However, the shape of a joint also has a great effect on its service life. During the reflow process, the solder joint experiences heating, melting, cooling and then solidification. Conventionally, the shape of a solder joint is often predicted using the energy method after the reflow process. This, however, does not consider the evolution of the solder alloy during reflow. In this study, a computer aided analytical system is developed based on computational heat transfer and fluid dynamics techniques to simulate the shape evolution of solder joints during reflow. Experimental observations of the shape evolution of the joint during reflow were also conducted. The simulation results obtained for a solder ball 760 μm in diameter on a rectangular pad were found to be consistent with the experimental observations.     

Modelling of electromagnetic processes in system 'welding arc–evaporating anode' Part 2 – model of arc column and anode metal

Abstract

A mathematical model of electromagnetic processes occurring in the 'arc column–anode region–evaporating anode' system is suggested. Electric charge transfer processes in the multicomponent plasma of the electric arc and in the bulk of the metallic anode are described using the Ohm's law and charge conservation law generalised for a case of discontinuity of the electric field potential at the boundary between the arc plasma and the anode surface. A procedure was developed for finding the numerical solution of the stated problem by the shock capturing method, allowing modelling of the electromagnetic processes in the 'welding arc–evaporating anode' system in the presence of a reverse potential jump in the anode region (negative anode drop). Results of modelling of the said processes for gas metal arc and plasma transferred arc welding of steel in an inert gas (Ar) atmosphere are given.     

10—THE MECHANICS OF FRICTION-TWISTING

An analysis is given from which equations can be derived that relate the variations of twist factor, tension, and yam path through a false-twist friction spindle. The solution of these (differential) equations leads to predictions about the dependence of over-all twist factor and tension ratio on, among other parameters, the ratio of yam speed to spindle speed, the angle of wrap, and the input tension. These are compared with the early experimental results of Arthur and Weller and with more recent results.

The equations also yield the variation of twist factor and tension over the spindle surface and could be used to estimate wear.

The early part of the analysis would have general application in any situation in which a yarn is moving over a surface.