A Distributed Query Processing Engine

Wireless sensor networks (WSNs) are formed of tiny, highly energy-constrained sensor nodes that are equipped with wireless transceivers. They may be mobile and are usually deployed in large numbers in unfamiliar environments. The nodes communicate with one another by autonomously creating ad-hoc networks which are subsequently used to gather sensor data. WSNs also process the data within the network itself and only forward the result to the requesting node. This is referred to as in-network data aggregation and results in the substantial reduction of the amount of data that needs to be transmitted by any single node in the network. In this paper we present a framework for a distributed query processing engine (DQPE) which would allow sensor nodes to examine incoming queries and autonomously perform query optimisation using information available locally. Such qualities make a WSN the perfect tool to carryout environmental\ud monitoring in future planetary exploration missions in a reliable and cost effective manner

Doctoral Education and Academic Research (in India)

[Excerpt] The state of doctoral education and academic research in India is poor and the country has scant representation among the world’s great universities. The decline has happened in spite of early achievements. Reasons behind this are complex and defy easy explanations. Several probable causes in terms of resources / facilities / opportunities granted to Ph.D. students, faculty quality, financial resources, academic leadership and other issues are explored and some suggestions for improvement are provided

An Application-Tailored MAC Protocol for Wireless Sensor Networks

We describe a data management framework suitable for wireless sensor networks that can be used to adapt the performance of a medium access control (MAC) protocol depending on the query injected into the network. The framework has a\ud completely distributed architecture and only makes use of information available locally to capture information about network traffic patterns. It allows\ud nodes not servicing a query to enter a dormant mode which minimizes transmissions and yet maintain an updated view of the network. We then introduce an Adaptive, Information-centric and Lightweight MAC\ud (AI-LMAC) protocol that adapts its operation depending on the information presented by the framework. Our results demonstrate how transmissions are greatly reduced during the dormant mode. During the active mode, the MAC\ud protocol adjusts fairness to match the expected requirements of the query thus reducing latency. Thus such a data management framework allows the MAC to operate more efficiently by tailoring its needs to suit the requirements of the application

An adaptive directed query dissemination scheme for wireless sensor networks

This paper describes a directed query dissemination scheme, DirQ that routes queries to the appropriate source nodes based on both constant and dynamic-valued attributes such as sensor types and sensor values. Unlike certain other query dissemination schemes, location information is not essential for the operation of DirQ. DirQ uses only locally available information in order to route queries accurately. Nodes running DirQ are able to adapt autonomously to changes in network topology due to certain cross-layer features that allow it to exchange information with the underlying MAC protocol. DirQ allows nodes to autonomously control the rate of sending update messages in order to keep the routing information updated. The rate of sending updates is dependent on both the number of queries injected into the network and the rate of variation of the measured physical parameter. Our results show that DirQ spends between 45% and 55% the cost of flooding

Dynamics of an Urban Forest in Response to Urban Development and Management Initiatives — Case of Bukit Timah Nature Reserve

Singapore, a tropical island of only 716 km², has substantial land under forest. But rapid urbanisation coupled with the scarcity of land has also resulted in extensive land clearance. Though highly urbanised, Singapore has managed to retain 4.5% of the land area under nature conservation, and 2.9% under closed forest. Out of four protected areas, two of these, the Central Water Catchment Forest (CWC forest) and Bukit Timah Nature Reserve (BTNR), are protected under the Parks and Trees Act of 2005 with a total area of 3,043 ha. Though originally connected, these two forests were separated from each other by a major highway, leaving BTNR, the smaller of the two, with a total land area of 163 hectares, surrounded by not just the highways, but also by a fast developing urban residential area. The forest boundaries have seen dense urban development as close as only 50 m from the forest edge. As a result, micro-climatic parameters such as atmospheric temperature, relative humidity, soil surface temperature, light conditions, wind velocity, all have seen significant changes over time and the gradient of such changes are drastic and steep along most forest verges. Currently some ameliorating steps are being taken by the forest management to counter the ill effects of too much encroachment and fragmentation

Technological Aspects of Low Shaft Furnace Process

WHILE the primary object of the low shaft furnace is to produce commercial grades of pig from iron-ore and fuel unsuitable for smelting in the conventional blast furnace, there is a wide diversity ill the design of the furnace, all of which are characterised only by the shortness of the shaft and the smallr.ess of one of the horizontal dimensions. Low shaft furnaces of circular,rectangular and oval hearths and with double rows of tuff tires have been tried. In the construction of the furnace, width is gove-rned by the ability of the blast to penetrate to the centre with minimum dust losses and for this reason a rectangular or oval cross-section is preferred. The height of the charge in the low shaft furnace seldom exceeds 16 ft. This low height widens the choice of ratio materials. The burden may, therefore, consist of friable ores and ore fines and fuels like small coke, non-coking coal, carbonised lignite briquette, or similar fuels of an inferior grade both from the point of view of physical strength and heating value, the cost of which compared to blast furnace coke is very low and which are available in abundance. The reduction of height causes the burden in a low shaft furnace to descend in 2 to 4 hours compared to 8 to 12 hours in a conventional blast furnace. With the shorter throughput time, the time of reaction afforded in the low shaft furnace becomes 1/3 to 1/5 of that in a blast furnace. It is, therefore, obvious that a suitable burden prepartion is necessary.Uniform distribution of the burden, reducibility of iron-ore, intimacy- of cotact between the oxide and the reductant on which the reaction time depends are to be taken into consideration for deci-ding the size and shape of the furnace. The height and the cross-section can be adjusted to meet the demands of the raw materials. But once the design has been worked for a particular set of conditions, treatment of raw materials widely varying in analyses, may not be economical.The low shaft furnace differs from the conventional blast furnace not only in design but also in the smelting operation. The raw materials smelted in the, blast furnace are somewhat similar in nature but those in the low shaft furnace vary eon-iderabl

Some Aspect of Service Failures at Elevated Temeratures

Service performance of metals and alloys at elevated temperatures is generally governed by creep and rupture strength required and corrosion conditions likely to be met with. The influence of factors like intergranular oxidation, decarburisation, carburisation , spheroi-disation, graphitisation , carbide precipitation and the formation of' sigma phase on failure at high temperat-ures have been outlined . Some recorded service failures are discussed and preventive measures indicated in some case

On Some Fundamental Aspects of Operational Parameters of Direct Reduction in Rotary Kiln

A rotary kiln for the reduction of iron oxides in solid state is essentially a continuous gas/solid reactor operating on either counter-current, or co-current flow of solids and gases. The factors affecting isothermal condi-tion in the reaction zone and heat transfer are indicated. Limited rate of heat release, poor heat transfer and leng-thy and rotation, the output can be increased by increa-sing the diameter. The degradation due to self grinding increases with diameter, while exhaust gas velocity is decreased lowering entrainment of solids. For reasonable reaction rate, an appropriate temperature profile has to be maintained. The reaction temperature is dependant on softening temperature of solids. The reactivity of fuel and reducibility of the ore are the rate determining fact-ors. The degree of metallization depends on the particle size and reducibility of the ore, temperature profile and reactivity of the fuel. All these factors should be consi- dered in designing a rotary kiln pilot plant and parti-cularly for evolving a commercial prototype