Pressure drop data in the laminar and turbulent region for Newtonian fluids flowing through 60 helical coils are presented. Coils of wide range of diameter and pitch are investigated to fulfil the snags existing in the previous investigations and to resolve the effect of coll pitch. The following correlations are obtained for Dt/Dc range 0.003 to 0.15 and p/Dc range 0 to 25.4. (1) For laminar flow: A/fSL -1 = 0.033(log /VD )40, where 1 < ND <3000.(2) For critical Reynolds number: NRg = 2 X 104(D,/2RC)°. (3) For turbulent flow: ?c -fST = 0.0075(D,/2RC)1/2, where 4500 < /VRe < 105.

except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights.Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) PrefaceWireless communication has emerged as an independent discipline in the past decades. Everything from cellular voice telephony to wireless data transmission using wireless sensor networks has profoundly impacted the safety, production, and productivity of industries and our lifestyle as well. After a decade of exponential growth, the wireless industry is one of the largest industries in the world. Therefore, it would be an injustice if the wireless communication is not explored for mining industry.Underground mines, which are characterized by their tough working conditions and hazardous environments, require fool-proof mine-wide communication systems for smooth functioning of mine workings and ensuring better safety. Proper and reliable communication systems not only save the machine breakdown time but also help in immediate passing of messages from the vicinity of underground working area to the surface for day-to-day normal mining operations as well as for speedy rescue operations in case of disaster. Therefore, a reliable and effective communication system is an essential requisite for safe working, and maintaining requisite production and productivity of underground mines. Most of the existing systems generally available in underground mines are based on line (wired) communication principle, hence these are unable to withstand in the disaster conditions and difficult to deploy in inaccessible places. Therefore, wireless communication is an indispensable, reliable, and convenient system and essential in case of day-to-day normal duty or disaster situations. However, at present there is no relevant book available in the global market regarding wireless communication technology in underground mines and hazardous areas. Therefore, a comprehensive textbook on wireless communication for underground mines is a vital need for mining and electronics engineers that provides a deeper understanding of the important subject and designing the intrinsic safe systems. Considering these facts, this book is written, incorporating various communication devices designed and developed by the authors for wireless communication in different areas of underground mines and their experiences in the fields.The wireless communication systems used on surface cannot be applied straightaway in underground mines due to high attenuation of radio waves in underground strata, besides presence of inflammable gases and hazardous environment...

The present paper deals with a weak non-linear stability problem of magneto-convection in an electrically conducting Newtonian fluid, confined between two horizontal surfaces, under a constant vertical magnetic field, and subjected to an imposed time-periodic boundary temperature (ITBT) or gravity modulation (ITGM). In the case of ITBT, the temperature gradient between the walls of the fluid layer consists of a steady part and a time-dependent oscillatory part. The temperature of both walls is modulated in this case. In the problem involving ITGM, the gravity field has two parts: a constant part and an externally imposed time periodic part, which can be realized by oscillating the fluid layer. The disturbance is expanded in terms of power series of amplitude of convection, which is assumed to be small. Using Ginzburg-Landau equation, the effect of modulations on heat transport is analyzed. Effect of various parameters on the heat transport is also discussed.

Dust from haul and transport roads are the major source of air pollution in opencast coal mining areas. Dust generated during mining operations pollutes air which causes different health problems. Various available techniques are implemented in the field to minimize and control dust in mining areas. However, they are not very effective because dust deposited on road surfaces are not removed by these techniques. For effective control of dust in opencast mining areas, it has to be regularly collected from road surfaces and may be converted into solid form, and subsequently can be used as a domestic fuel considering its physicochemical properties. The present paper describes a comparative study of qualitative and quantitative aspects of road dust samples of four coalfields of India. The pH of the dust was found to be in the range of 5.1-7.7. Moisture, ash, volatile matter, fixed carbon, water-holding capacity, bulk density, and specific gravity of dust samples were found to be in the range of 0.5-3.0%, 45-76%, 12.6-20.0%, 10.2-45.3%, 21.17-31.71%, 1.15-1.70, and 1.73-2.30 g cm(-3), respectively. Observing the overall generation and characteristics of coal dust, it is suggested that coal dust from haul and transport roads of mining areas can be effectively collected and used as domestic fuel.

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