The very nature of human exploration and the recent disaster of Titan submarine makes scientists rethink how things should be done in a flawless manner. Structural failure and quick location identification of the lost object are two significant parts. This paper has focused on the localization part, a pragmatic approach has been revisited where limited resources in a vast area with time constraint makes the approach idiosyncratic. In UWSN, trilateration or multilateration is exploited to assess the location of the deployed hosts; having three or more reference nodes to localize a deployed sensor is not pragmatic at all. On the other hand, non-linear equations are usually solved in conventional methods where degree-of-freedom is uncertain to lead to an exclusive solution. In this paper, a pragmatic method of determining the coordinates of submerged sensors (the lost submarine) with a single mobile beacon (the rescue ship) has been devised which requires no preinstalled infrastructure or any reference point. Moreover, Cayley-Menger determinant and linearized trilateration have been used to determine the coordinates of the nodes where none of nodes have a priori knowledge about its location.

Chemotaxis of fibroblasts and other mesenchymal cells is critical for embryonic development and wound healing. Fibroblast chemotaxis directed by a gradient of platelet-derived growth factor (PDGF) requires signaling through the phospholipase C (PLC)/protein kinase C (PKC) pathway. Diacylglycerol (DAG), the lipid product of PLC that activates conventional PKCs, is focally enriched at the up-gradient leading edge of fibroblasts responding to a shallow gradient of PDGF, signifying polarization. To explain the underlying mechanisms, we formulated reaction-diffusion models including as many as three putative feedback loops based on known biochemistry. These include the previously analyzed mechanism of substrate-buffering by myristoylated alanine-rich C kinase substrate (MARCKS) and two newly considered feedback loops involving the lipid, phosphatidic acid (PA). DAG kinases and phospholipase D, the enzymes that produce PA, are identified as key regulators in the models. Paradoxically, increasing DAG kinase activity can enhance the robustness of DAG/active PKC polarization with respect to chemoattractant concentration while decreasing their whole-cell levels. Finally, in simulations of wound invasion, efficient collective migration is achieved with thresholds for chemotaxis matching those of polarization in the reaction-diffusion models. This multi-scale modeling framework offers testable predictions to guide further study of signal transduction and cell behavior that affect mesenchymal chemotaxis.

Wireless communication applications have become more prominent in terrestrial than underwater. However, in the recent years, researchers have shown fervent interest to explore and fulfil the needs of a multitude of underwater applications. UWSN (underwater wireless sensor network) is envisioned to enable application for oceanographic data collection and offshore exploration for the profusion of wealth underwater world has. It's not only the wealth; marine life helps determine the very nature of our planet at a very fundamental level and for its sustenance, it becomes crucial to obtain accurate environmental data using underwater sensors to provide and maintain sanctuary for the marine life. Besides, advanced robot navigation, autonomous underwater vehicles control, find lost objects, estuary monitoring and pollutant tracking also require accurate localization. In addition to underwater sensors, UWSN may also comprise of surface stations and autonomous underwater vehicles. Regardless of the type of deployment and configuration, the location of sensors needs to be determined for meaningful interpretation of the sensed data.

This paper studies and analyzes the influence of temperature, depth and salinity on speed of acoustic signal for a vertical water column. In underwater wireless sensor networks (UWSN), determination of precise acoustic signal is sometimes necessary to determine the coordinates of sensors for the validity of data. The effect of temperature on sound speed is predominant where temperature change is noticeable. In the deep ocean where temperature change is very nominal, depth (pressure) becomes predominant and salinity effect is even less. In this paper we have shown how these variables affect acoustic signal speed for a specific depth of water column where temperature, depth and salinity changes are linear.

This paper investigates the problem of localizing submerged sensors and provides a new mechanism to determine the coordinates of those sensors using only one beacon node. In underwater wireless sensor networks (UWSN), precise coordinate of the sensors that actuate or collect data is vital, as data without the knowledge of its actual origin has limited value. Mostly, multi-lateration technique is used to determine the location of the sensors with respect to three or more known beacon nodes where distance between them is measured considering the roundtrip time of acoustic signal. However, this method of measuring distances gives erroneous results due to a number of factors, including relative angular stand of the nodes. In this study, a new method of determining the underwater distances between beacon and sensor nodes has been presented using combined radio and acoustic signals, which has better immunity from multipath fading. Moreover, Cayley-Menger determinant is used to determine the coordinates of the nodes where none of nodes have a priori knowledge about its location. Simulation results validate the proposed mathematical models by computing coordinates of sensor nodes with negligible errors.

A spread-spectrum system that does not have a separate state for initial code acquisition is presented. A uniform random variate selects one of several Gold codes for transmission, thus removing the notion of pseudorandom codes from spread-spectrum systems, making the effective code length infinite, and leading to acquisitionless systems. Because coding is critical to the proposed multiaccess frequency-hopping (FH) system, more powerful codes are needed. The performance of the proposed multiaccess system using the combined modulation and coding technique (trellis) concatenated with Reed-Solomon codes in partial-band jamming is investigated. The FH multiaccess performance of noncoherent soft detection of MFSK in association with trellis coding is introduced and the performance compared to that using RS outer/RS inner concatenated codes.>