Sensor Management for Tracking in Sensor Networks

We study the problem of tracking an object moving through a network of wireless sensors. In order to conserve energy, the sensors may be put into a sleep mode with a timer that determines their sleep duration. It is assumed that an asleep sensor cannot be communicated with or woken up, and hence the sleep duration needs to be determined at the time the sensor goes to sleep based on all the information available to the sensor. Having sleeping sensors in the network could result in degraded tracking performance, therefore, there is a tradeoff between energy usage and tracking performance. We design sleeping policies that attempt to optimize this tradeoff and characterize their performance. As an extension to our previous work in this area [1], we consider generalized models for object movement, object sensing, and tracking cost. For discrete state spaces and continuous Gaussian observations, we derive a lower bound on the optimal energy-tracking tradeoff. It is shown that in the low tracking error regime, the generated policies approach the derived lower bound

Sensor Scheduling for Energy-Efficient Target Tracking in Sensor Networks

In this paper we study the problem of tracking an object moving randomly through a network of wireless sensors. Our objective is to devise strategies for scheduling the sensors to optimize the tradeoff between tracking performance and energy consumption. We cast the scheduling problem as a Partially Observable Markov Decision Process (POMDP), where the control actions correspond to the set of sensors to activate at each time step. Using a bottom-up approach, we consider different sensing, motion and cost models with increasing levels of difficulty. At the first level, the sensing regions of the different sensors do not overlap and the target is only observed within the sensing range of an active sensor. Then, we consider sensors with overlapping sensing range such that the tracking error, and hence the actions of the different sensors, are tightly coupled. Finally, we consider scenarios wherein the target locations and sensors' observations assume values on continuous spaces. Exact solutions are generally intractable even for the simplest models due to the dimensionality of the information and action spaces. Hence, we devise approximate solution techniques, and in some cases derive lower bounds on the optimal tradeoff curves. The generated scheduling policies, albeit suboptimal, often provide close-to-optimal energy-tracking tradeoffs

Prawn fishery resources of Cochin backwaters

Increasing utilization of prawns both in the internal and external markets has created a large demand for this commodity in recent years. While efforts arebeing made to meet such demands through more intensified exploitation of the resources from the conventional prawn grounds, often serious shortages of the raw ma terial have been experienced due to the fluctuations in the fishery

Some aspects of prawn culture in the seasonal and perennial fields of Vypeen island

Prawn culture is extensively practised in the paddy fields (seasonal fields) and other low lying areas (perennial fields) of Vypeen Island. Though the seasonal fields are found to be more productive, the perennial fields, which are available for prawn culture throughout the year, are not less important. Prawns stay for longer time and attains larger size in this type of fields. The average annual production of prawns is 903.3 and 838.6 kg|ha in the seasonal and perennial fields respectively. The month-wise catch rates show that higher catch rate is generally observed in January-iMarch period. Four species of penaeid prawns, Metapenaeus dobsoni, M. monoceros, Penaeus indicus and P. monodon constitute the culture fishery of which M. dobsoni contributes more than 50% of the catch. It is observed that M. dobsoni in the perennial fields grow at an average rate of 10.0 mm per month. Although, the total expenditure to run the seasonal field is higher than that of the perennial fields, the net income realised from the seasonal field is always found to be better. It is therefore concluded that the paddy field prawn culture is more profitable than the culture of prawns in perennial fields

A case study of the English language practices of six learners in a desegregated urban South African school.

Faculty of Humanities School of Education 0516698x [email protected] research report explores the English language practices of six Grade 10 learners in a desegregated Johannesburg school as well as the ways in which the learners position themselves and others as users of English and other languages. The context of the study is desegregated schooling that is a consequence of the demise of apartheid with its policies of separation of people on racial and ethnic grounds. I draw on post-structuralist theorizing of language and identity in thinking about the relationship between language and identity (Hall, 1992a; Weedon, 1997; Zegeye, 2001) with an emphasis on the productive force of language in constituting identity (Pennycook, 2004). Also significant in this research report are the hybridity theories of Bhabha (1994) and Hall (1992b) and their critiques as well as the post-structuralist concepts of ‘positioning’ (Davis and Harrè, 1990) and ‘investment’ (Norton (Pierce), 1995; 1997). A further important strand in this study are the politics of English as a global language and language of power. The overall design of the project is qualitative, using ethnographic methods and drawing on the traditions of school ethnography. In analyzing the data, I argued that English constitutes and is experienced as a major part of the participants’ identities. I also state that through learners’ language practices and positioning of themselves and others as speakers of language, multiple and at times contradictory identities are continually being constructed and reconstructed. I also argue that the learners’ desire to be proficient in English and use of prestigious accents and varieties of English is not about a simple process of assimilation into dominant discourses. Assimilation as I contend, takes place under complex processes of contestation and appropriation that involves constant crossing of borders and authorization of hybridities. I have also argued that the post-apartheid youth find themselves in a situation where internalised racialised categories of apartheid ideology continue to be relevant in their understanding of issues but that they are not constrained by them in their lived experience of boundary crossing and fashioning of hybrid identities

Application of Multiprotocol Medical Imaging Communications and an Extended DICOM WADO Service in a Teleradiology Architecture

Multiprotocol medical imaging communication through the Internet is more flexible than the tight DICOM transfers. This paper introduces a modular multiprotocol teleradiology architecture that integrates DICOM and common Internet services (based on web, FTP, and E-mail) into a unique operational domain. The extended WADO service (a web extension of DICOM) and the other proposed services allow access to all levels of the DICOM information hierarchy as opposed to solely Object level. A lightweight client site is considered adequate, because the server site of the architecture provides clients with service interfaces through the web as well as invulnerable space for temporary storage, called as User Domains, so that users fulfill their applications' tasks. The proposed teleradiology architecture is pilot implemented using mainly Java-based technologies and is evaluated by engineers in collaboration with doctors. The new architecture ensures flexibility in access, user mobility, and enhanced data security

Studies on riverine flora of Pamba river basin, Kerala

Riparian forests are ecotonal assemblage of aquatic and terrestrial habitats. The composition of riparian forests of Pamba River is an amalgamation of riverine, evergreen, deciduous and wetland flora. The floristic investigation of the riparian forests of Pamba river basin revealed taxonomically 433 species which include 410 angiosperms, 3 gymnosperms and 20 pteridophytes. The dominant families based on the number of species are Poaceae, Euphorbiaceae, Rubiaceae, Cyperaceae and Fabaceae. The flora consists of a diverse blend of 99 evergreen, 36 deciduous, 50 wetland, 15 shola-grassland, 46 cultivated and 44 riverine components. The river basin holds 17.5 % endemism and 17 RET species. The riparian tree species identified in the present investigation are _Barringtonia racemosa_, _Calophyllum inophyllum_, _Crateva magna_, _Dillenia indica_, _Elaeocarpus tuberculatus_, _Garcinia gummi-gutta_, _Humboldtia vahliana_, _Largestromea speciosa_, _Neolamarkia kadamba_, _Ochrenauclea missionis_, _Syzigium salicifolium_, _Talipatri tiliaceaum_ and _Trewia nudiflora_. It is assumed that these potential tree species might have a crucial role to maintain the ecological integrity of the riparian zones and floodplain for the restoration of Pamba river