The effects of rotational flow, viscosity, thickness, and shape on transonic flutter dip phenomena

The transonic flutter dip phenomena on thin airfoils, which are employed for propfan blades, is investigated using an integrated Euler/Navier-Stokes code and a two degrees of freedom typical section structural model. As a part of the code validation, the flutter characteristics of the NACA 64A010 airfoil are also investigated. In addition, the effects of artificial dissipation models, rotational flow, initial conditions, mean angle of attack, viscosity, airfoil thickness and shape on flutter are investigated. The results obtained with a Euler code for the NACA 64A010 airfoil are in reasonable agreement with published results obtained by using transonic small disturbance and Euler codes. The two artificial dissipation models, one based on the local pressure gradient scaled by a common factor and the other based on the local pressure gradient scaled by a spectral radius, predicted the same flutter speeds except in the recovery region for the case studied. The effects of rotational flow, initial conditions, mean angle of attack, and viscosity for the Reynold's number studied seem to be negligible or small on the minima of the flutter dip

Efficacy of Gravity Separation as an Alternative to Froth Flotation for Treating Jharia group Coal fines

In general, the Indian coals are difficult-to-wash due to their drift origin. Recovery of clean coal from coal fines is continue to he cost in-effective. Even though several advanced flotation technologies have been commercialized to treat fines, the results are not comparable with the washability data of fines. The Jharia group of coal fines are treated at Tata Steel presently in froth flotation. Keeping merit of gravity separation in view, the test results with water-only cyclone as an alternative gravity method to froth flotation for treating Jamadoba coal fines have been presented in this paper

Rapid Determination of Copper in Copper Ores

Low grade copper ores and copper ores in association with considerable quantities of other elements such as iron, lead, zinc and vanadium require a separational step wherein copper is generally seperated as sulphide either with sodium thiosulfate or with thiocetamide. In these methods the precipitated copper sulfide is ignited to cupric oxide, dissolved in dilute nitric acid and titrated idometrically. In a recent methorl wet oxidation of precipitated copper sulfide is effected with nitric acid ,and perchloric acid and titrated with disodium ethylene diamine tetraacetate (EDTA). The authors' work on the beneficiation of low grade copper ores. and extraction of copper, from these ores has necessitated developing a rapid and accurate method for the determination of copper. A separational step wherein cupric ion could be preci-pitated as cuprous oxide has been introduced to avoid ignition of copper sulfide to cupric oxide, which is time consuming

Organisational synergies, dissonance and spinoffs

Spinoff firms are a distinct class of new entrants across industries. The causes for their emergence have been widely investigated in the literature. However, the role of team environments has received little attention. On the one hand, talented individuals may find it necessary to team up with others to utilise complementary knowledge and generate synergies. On the other hand, some types of team production environments may exhibit dissonance and motivate individuals to leave them. This study introduces environments of synergy and dissonance utilising team production functions and utilises them to analyse how team environments vary in their propensity to generate spinoffs. We show that the teams exhibiting synergy are not likely to spawn spinoffs but a new idea from a team member gets implemented only if it is of exceptional quality. The concepts of synergy and dissonance can also be utilised to analyse other phenomena such as mergers and alliances

Crafts and gear used for marine fishing along the Andhra Pradesh coast

Until the middle of nineteen sixties fishing for marine finfishes and shellfishes along the Andhra Pradesh coast used to be carried out employing indigenous non-mechanised crafts. Subsequently trawlers and later mechanised vessels operating gillnets came into use which resulted in the increased fish production. Use of outboard engine on indigenous crafts for reaching fishing grounds is a recent feature of near the coast fishing. The different kinds of non-mechanised and mechanised crafts and gear employed in the region are dealt with in this article

Bounds and error control for eigenvalues

Control and estimation of errors are important but difficult aspects of any analysis from which the numerical results are necessarily approximate. The order of difficulty is greater for local or distributed quantities like stresses and displacements than for global Of integrated parameter~ like eigenvalues and stiffnesses. To really bound a desired quantity between a pair of dose upper and lower bounds one should obtain either an oscillatory but clear convergence or, preferably, two rapidly converging sequences one from above and the other from below. Application of the two complementary variational principles of energy and complimentary energy, when both are possible to apply, do yield upper and lower bound approximations. But these or other alternate methods are generally expensive. On the other hand it would be advantageous if one basic procedure could be perturbed in a simple manner to provide both lower and upper bounds and to refine the solution and control the errors without undue effort. This paper discusses this concept and presents three powerful methods to closely bound any desired parameter in a problem. These are particularly valuable for eigenvalue problems

A Novel Multi-Band Patch Antenna on Metamaterial Substrate for Ku band applications

In this paper, a metamaterial based compact multiband microstrip antenna is proposed which can give high gain and directivity. Metamaterial are periodic structures and have been intensively investigated due to the particular features such as ultra-refraction phenomenon and negative permittivity and/or permeability. A metamaterial based microstrip patch antenna with enhanced characteristics and multi band operation will be investigated in this work. The multiple frequency operation will be achieved by varying the capacitance of the metamaterial structure with the help of metallic loadings placed in each metamaterial unit cells. The potential impacts will be miniaturization, reduced cost and reduced power consumption since multiple antennas operating at different frequencies are replaced by a single antenna which can operate at multiple frequencies. The proposed microstrip patch antenna will have its frequencies of operation in the Ku band. The proposed structure is simulated using HFSS