Uniform discrimination of pattern orientation by honeybees

To explore how honeybees, Apis cerana, discriminate the orientation of patterns, we trained workers to discriminate between a black stripe of a certain orientation on a white disc and a pure white disc. We tested trained bees for their ability to discriminate between the trained orientation and deviations from it. This was done either in a dual choice situation where the bees had to choose between the trained orientation and one deviation from it at a time, or in a multiple choice situation where bees had to choose simultaneously between the trained orientation and 11 successive deviations from it. In the dual choice situation, bees did not discriminate behaviourally between the trained orientation and deviations up to 25 degrees, whereas in a multiple choice situation, they discriminated between the trained orientation and a deviation of 15 degrees or more. Thus, orientation can be analysed more precisely in multiple choice experiments. The response of the bees was independent of the orientation of the trained orientation; the 12 different trained orientations all yielded identical results. This finding, considered together with a model that we present for orientation discrimination, suggests that at least three orientation-sensitive channels (a neuron or a set of neurons that respond maximally to a particular orientation) participate in the analysis of pattern orientation. (c) 1998 The Association for the Study of Animal Behaviour.     

Polyaniline-based nanocomposite materials for hydrogen storage

Nanomaterials have diverse tunable physical properties as a function of their size and shape due to strong quantum confinement effect and large surface to volume ratio. On basis of these facts, nanocomposite materials can be considered as strong candidates for hydrogen storage. In the present work, we report a novel conducting polymeric nanocomposite material for hydrogen storage. Conducting polymer-based nanocomposites were modified using carbon nanotubes as filler material. This further increased the porous structure of the nanocomposite and the number of binding sites, which in turn enhances the hydrogen storage capacity. Additionally, fine aluminum powder was added to the polymeric nanocomposite, which further increased the hydrogen sorption of the material. The modified conducting polymeric nanocomposites were characterized with various analytical techniques including FTIR, DSC, TGA and SEM. Adsorption and desorption experiments are conducted using a Sieverts-type volumetric PCT instrument. Further experiments are in progress to understand the hydrogen storage mechanism in the proposed conducting polymer nanocomposites.     

Synthesis and characterization of polyamides containing arylene sulfide-sulfone groups

Polyamides containing arylene sulfide as well as arylene sulfide-sulfone linkages were prepared from bis(4-phenylthio)dibenzoyl chloride (BPCl), 4,4′-[sulfonylbis(4-phenylthio)]dibenzoyl chloride (SPCl) and aromatic diamines both by solution and interfacial polymerization techniques. In the solution polymerization the effect of two different acid acceptors, lithium chloride and triethylamine, on inherent viscosity of the polyamides was studied. The effect of aromatic sulfone ether diamines and conventional aromatic diamines on viscosity and thermal properties of polyamides was also investigated. The polyamides prepared were characterized by IR, ¹H NMR, elemental analysis, solution viscosity, thermogravi-metry, differential scanning calorimetry and X-ray diffraction. Thermal and physical properties of polyamides prepared from BPCl and SPCl were compared.     

Heuristics for operator allocation and sequencing in just-in-time flow line manufacturing cell

Group technology tries to exploit the similarity between parts and machines and forms machine groups and part families. Just-in-time production tries to manufacture the parts whenever required there by reducing the inventory and eliminating waste.

In order to apply JIT in a GT cell, the cell is divided into modules and parts move from one module to another in small transfer batches. This paper addresses the problem of operator allocation for the modules and sequencing the variety of parts with the objective of minimizing the makespan.

Six different methodologies have been presented and the results compared in terms of makespan and computational time.     

155 W CW optical power from 1 cm monolithic AlGaAs/InGaAs laserdiode array

155 W continuous-wave output power from a 1 cm wide monolithic AlGaAs/InGaAs laser diode array with an emitting aperture of 4800 μm has been demonstrated at a cooling water temperature of 3°C. A continuous-wave output power of 72 W was achieved at room temperature with an emitting aperture of 1600 μm. High T₀ was observed for the laser structures     

Evaluation of decision fusion strategies for effective collaboration among heterogeneous fault diagnostic methods

Numerous methodologies for fault detection and identification (FDI) in chemical processes have been proposed in literature. However, it is extremely difficult to design a perfect FDI method to efficiently monitor an industrial-scale process. In this work, we seek to overcome this difficulty by using multiple heterogeneous FDI methods and fusing their results so that the strengths of the individual FDI methods are combined and their shortcomings overcome. Several decision fusion strategies can be used for this purpose. In this paper, we study the relative benefits of utility-based and evidence-based decision fusion strategies. Our results from a lab-scale distillation column and the popular Tennessee Eastman challenge problem show that in situations where no single FDI method offers adequate performance, evidence-based fusion strategies such as weighted voting, Bayesian, and Dempster-Shafer based fusion can provide (i) complete fault coverage, (ii) more than 40% increase in overall fault recognition rate, (iii) significant improvement in monitoring performance, and (iv) reduction in fault detection and diagnosis delays.     

A feedback-based implementation scheme for batch process optimization

The terminal-cost optimization of a control–affine nonlinear system leads to a discontinuous solution that can be characterized in a piecewise manner. To implement such an optimal trajectory despite disturbances and parametric uncertainty, a cascade optimization scheme is proposed in this paper, where optimal reference signals are tracked. Optimality is achieved by the appropriate definition of reference signals (input bounds, state constraints, or switching functions) to track in various sub-intervals. Furthermore, conservatism is introduced into the optimization problem to ensure satisfaction of path constraints in the presence of uncertainty. Finally, the proposed cascade optimization scheme is illustrated on a simulation of a fed-batch penicillin fermentation plant.     

Design characteristics of in situ and operando ultraviolet-visible and vibrational spectroscopic reaction cells for heterogeneous catalysis

This article focuses on reaction cells for in situ/operando studies of heterogeneous catalysts by ultraviolet-visible (UV-vis) and vibrational (IR and Raman) spectroscopies and mainly focuses on transmission, internal reflection, diffuse reflectance, and scattering techniques. Its objective is to present a general overview of the most common commercial and homemade reaction cell designs, their main design characteristics, and limitations to serve as a guide for their selection or the design of new in situ/operando cells. It will be shown that there are currently many designs for different specific catalytic applications. However, an ideal reaction cell for a wide range of catalytic in situ and operando reaction conditions does not exist (yet), that is, with low dead volume (i.e., for fast dynamic response to process feed changes, within tens of seconds), high temperatures (> 500°C), high pressures (>30 bar), low cost, enough sample capacity (for operando studies, in the tens of mg), good spectroscopic response, resemblance to laboratory scale reactors, and reactor wall inertness, among others.