Fabrication process of open surfaces by robotic fibre placement

Composite materials are being used extensively in many industrial sectors. They offer excellent material properties compared to other structural materials available. However, the traditional fabrication process using manual hand lay-up is time consuming and labour intensive. Therefore, robotic fibre placement has been introduced to overcome these drawbacks. This approach may greatly reduce cycle time and manufacturing costs. This paper describes the overall strategy for the establishment of a flexible robotic fibre placement technique. The fabrication process planning of this new technique is presented. Three different types of fibre placement for open surfaces are discussed. These include simulation-based fibre path generation, fibre steering, and sensory-based contour following methodologies. The system architecture for the process control is also presented.     

Efficient financial time series prediction with evolutionary virtual data position exploration

Prediction of stock index remains a challenging task of the financial time series prediction process. Random fluctuations in the stock index make it difficult to predict. Usually the time series prediction is based on the observations of past trend over a period of time. In general, the curve the time series data follows has a linear part and a non-linear part. Prediction of the linear part with past history is not a difficult task, but the prediction of non linear segments is difficult. Though different non-linear prediction models are in use, but their prediction accuracy does not improve beyond a certain level. It is observed that close enough data positions are more informative where as far away data positions mislead prediction of such non linear segments. Apart from the existing data positions, exploration of few more close enough data positions enhance the prediction accuracy of the non-linear segments significantly. In this study, an evolutionary virtual data position (EVDP) exploration method for financial time series is proposed. It uses multilayer perceptron and genetic algorithm to build this model. Performance of the proposed model is compared with three deterministic methods such as linear, Lagrange and Taylor interpolation as well as two stochastic methods such as Uniform and Gaussian method. Ten different stock indices from across the globe are used for this experiment and it is observed that in majority of the cases performance of the proposed EVDP exploration method is better. Some stylized facts exhibited by the financial time series are also documented.

     

Coiling/uncoiling behaviour of sodium polystyrenesulfonate in 2‐ethoxyethanol–water mixed solvent media as probed using viscometry

Precise measurements of the viscosities of solutions of sodium polystyrenesulfonate in water and in 2‐ethoxyethanol–water mixtures containing varying amounts of 2‐ethoxyethanol have been performed at 308.15, 313.15, 318.15 and 323.15 K. The intramolecular contributions to the reduced viscosities of the polyelectrolyte solutions were obtained through isoionic dilution maintaining the total ionic strengths of the solutions at polyelectrolyte concentrations of 0.0033, 0.0054 and 0.0080 eq L^?1 with sodium chloride. The Huggins constants were also obtained from the experimental data. The influences of the medium and the temperature on the intramolecular contributions to the reduced viscosities as well as on the Huggins constants have been interpreted from the points of view of the conformational characteristics and polyelectrolyte–solvent and polyelectrolyte–polyelectrolyte interactions prevailing in the polyelectrolyte solutions under investigation. Polyion chains were found to coil upon addition of 2‐ethoxyethanol to water or upon an increase of temperature. Thermodynamic affinities for polyelectrolyte–solvent and polyelectrolyte–polyelectrolyte interactions were found to depend greatly on the medium. © 2014 Society of Chemical Industry     

Development of a novel flexure-based microgripper for high precision micro-object manipulation

Micro-scaled parts with dimension below 1 mm need to be manipulated with high precision and consistency in order to guarantee successful microassembly process. Often these requirements are difficult to be achieved particularly due to the problems associated with the structural integrity of the grasping mechanism which will affect the accuracy of the manipulation. Furthermore, the object's texture and fragility imply that small perturbation by the grasping mechanism can result in substantial damage to the object and leads to the degradation of its geometry, shape, and quality. This paper focuses on the unification of two designing approaches to develop a compliant-based microgripper for performing high precision manipulation of micro-objects. A combination of Pseudo Rigid Body Model (PRBM) and Finite Element Analysis (FEA) technique has proven to improve the design efficiency by providing the essential guideline to expedite the prototyping procedure which effectively reduces the cost and modeling time. An Electro Discharge Machining (EDM) technique was utilized for the fabrication of the device. Series of experimental studies were conducted for performance verification and the results are compared with the computational analysis results. A high displacement amplification and maximum stroke of 100 μm can be achieved.     

A lumped parameter element for the analysis of hyperbolic paraboloid shells

This paper presents the derivation of the stiffness matrix for a lumped parameter hyperbolic paraboloid shell element. This element is used to obtain solutions to hyperbolic paraboloid shells with various edge conditions. Numerical example for three types of support conditions (a simple support, a clamped edge and a shell supported by concentric edge beams) are presented. To illustrate the applicability of the method, the results obtained by the lumped parameter element are compared with those obtained by well-known methods of analysis such as the variational procedure, the finite difference and the finite element method.     

Some remarks on Bianchi type-II, VIII, and IX models

Within the scope of anisotropic non-diagonal Bianchi type-II, VIII, and IX spacetimes it is shown that the off-diagonal components of the Einstein equations impose severe restrictions on the components of the energy-momentum tensor (EMT) in general. We begin with a metric with three functions of time, a(t), b(t), and c(t), and two spatial ones, f(z) and h(z). It is shown that if the EMT is assumed to be diagonal, and f = f(z), in all cosmological models in question b ∝ c, and the matter distribution is isotropic, i.e., T ₁ ¹ = T ₂ ² = T ₃ ³ . If f = const, which is a special case of BII models, the matter distribution may be anisotropic, but only the z axis is distinguished, and in this case b(t) is not necessarily proportional to c(t).     

Optimization of nitrilase production from a new thermophilic isolate

A new thermostable nitrilase‐producing isolate identified as Streptomyces sp. MTCC 7546 has been studied extensively for the optimization of enzyme production operating in batch mode. The benzonitrile was observed as inducer of nitrilase production. The isolate showed maximum nitrilase production after 24 h of incubation at optimal conditions. The strain grows well on a variety of carbon sources and produces the nitrilase that catalyses the hydrolysis of nitriles to acids without formation of amides. The enzyme is mostly active against mono‐ and di‐aliphatic nitriles (10 mmol L^?1) at pH of 7.4 and at a temperature of 50 °C. Copyright © 2007 Society of Chemical Industry     

Synthetic Biology: A New Tool for the Trade

Protein–protein interactions are fundamental to many biological processes. Yet, the weak and transient noncovalent bonds that characterize most protein–protein interactions found in nature impose limits on many bioengineering experiments. Here, a new class of genetically encodable peptide–protein pairs—isopeptag‐N/pilin‐N, isopeptag/pilin‐C, and SpyTag/SpyCatcher—that interact through autocatalytic intermolecular isopeptide bond formation is described. Reactions between peptide–protein pairs are specific, robust, orthogonal, and able to proceed under most biologically relevant conditions both in vitro and in vivo. As fusion constructs, they provide a handle on molecules of interest, both organic and inorganic, that can be grasped with an iron grip. Such stable interactions provide robust post‐translational control over biological processes and open new opportunities in synthetic biology for engineering programmable and self‐assembling protein nanoarchitectures.     

Dynamic analysis of reconfigurable fixture construction by a manipulator

In a reconfigurable workholding system, the precise manipulation of fixture mechanisms by robot manipulators is performed against external kinematic constraints. Automation of such tasks requires development of dynamic model that can be utilised for establishment of control strategies. The sliding lower pairs form the basic structure of the fixture mechanisms; thus dynamic analysis of adjustment operations on sliding pairs becomes essential. In this paper, four types of fixture mechanisms for the reconfigurable workholding system are briefly presented. Sliding pairs are identified and briefly described as the basic structure of fixture mechanisms. Geometric and dynamic analyses for robotic adjustment of sliding pairs with built-in compliance are presented. The requirements to successfully perform the height adjustment of such sliding pairs with various geometric parameters are discussed. By taking into consideration the inertial forces and moments, constraint inequalities are obtained to ensure jam-free condition on sliding pairs during adjustment operations. Generalised inequalities for wedge-free condition are also developed and presented. In addition, the dynamic adjustment algorithms are discussed.     

On intuitionistic fuzzy sub-hyperquasigroups of hyperquasigroups

The notion of intuitionistic fuzzy sets was introduced by Atanassov as a generalization of the notion of fuzzy sets. In this paper, we consider the intuitionistic fuzzification of the concept of sub-hyperquasigroups in a hyperquasigroup and investigate some properties of such sub-hyperquasigroups. In particular, we investigate some natural equivalence relations on the set of all intuitionistic fuzzy sub-hyperquasigroups of a hyperquasigroup.