An Investigative Analysis of Underwater Wireless Sensor Network (UWSN) Security

Background: The last few decades bring an astonishing revolution in technology and electronics which enabling small pieces of electronic devices into handy equipment, called sensors. The sensors enable 75% area of the world covered by water. Which is hardly 5% been explored and has numerous applications. The security of underwater wireless sensors network (UWNS) communication is a prime concern to protect advantages from technology and application purpose. This paper explores UWSN architecture, vulnerabilities, attacks, and possible factors that challenge UWSN security and its applications. Objectives: The primary objective of this work is to analyze the vulnerable factors that cause security challenges and threats to UWSN applications. This study focuses on the intermediate uplink point of UWSN architecture and evaluates it in three different test cases. This would be beneficial to build a better solution by devising an appropriate scheme in the future. Method: The denial of service (DoS) attack is simulated using ns-3 and Aquasim-ng simulator to determine which factor(s) threatening to the UWSN environment. The simulation is performed under three idealized underwater scenarios; 1) depicts general UWSN (a hybrid architecture), 2) a special case depicts UWSN environment with only underwater components, ands 3) depicts another special case with underwater sink UWSN environment. Assuming all three test case environments are vulnerable and threats to UWSN security. Result: In all three scenarios, the average network performance in the normal transmission is 88% and about ± 3% deviation is observed. Also, it observed that scenarios 1 and 2 are influenced by the adversary interference or malicious activity while there are no such effects that occur in scenario 3 in the absence of intermediate radio link or surface sink node(s). Thus, experiments found that among others, the intermediate radio link(s) of the onshore surface sink(s) or surface buoy(s) are vulnerable and threats to UWSN. Conclusion: The simulation results and observations found that the intermediate up-link in UWSN architecture found to be more vulnerable which makes it insecure. While, in a pure underwater environment, seem to be more secure compared to the general UWSN environment. In the future, more factors will be evaluate in the same or different cases to determine the UWSN issues and other vulnerable factors

Advancement of Routing Protocols and Applications of Underwater Wireless Sensor Network (UWSN): A Survey

Water covers a greater part of the earth's surface. Even though we know very little about the underwater world as most parts of it remain unexplored. Oceans including other water bodies hold huge natural resources and also the aquatic lives. These are mostly unexplored and very few of those are known due to unsuited and hazardous environments for the human to explore. This vast underwater world can be monitored remotely from a distant location with much ease and less risk. To monitor water-bodies remotely in real-time, sensor networking has been playing a great role. It is needed to deploy a wireless sensor network over the volume which we want to surveil. For vast water bodies like oceans, rivers and large lakes, data is collected from the different heights of the water level which is sent to the surface sink. Unlike terrestrial communication, radio waves and other conventional mediums can't serve the purpose of underwater communication as they pose high attenuation and very reduced transmission range. Rather an acoustic medium can transmit data more efficiently and reliably in comparison to other mediums. To transmit data reliably from the bottom of the sea to the sinks at the surface, multi-hop communication is needed which must involve a certain scheme. For seabed to surface sink communication, leading researchers have proposed different routing protocols. The goal of these routing protocols is to make underwater communication more reliable, energy-efficient and delay efficient thus to improve the performance of the overall communication. This paper surveys the advancement and applications of the routing protocols which eventually helps in finding the most efficient routing protocol for the Underwater Wireless Sensor Network (UWSN).

Evaluation of Material Deformability and Pressure Distribution on a Die Surface under a Tool in Spot FSF

Friction-stir forming (FSF) is a friction-stir process invented by Nishihara in 2002. In FSF, a material is put on a die, and friction stirring is then conducted on its back surface. The material deforms and precisely fills the cavity of the die due to high pressure and heat caused by friction stirring. Materials in the process often display outstanding deformability and moldability. However, behavior of the material during the friction-stir process has not been sufficiently clarified as a metal forming process. In this paper, material deformability under a tool in spot FSF, i.e. FSF without tool travel, was investigated employing a die having holes. The authors conducted spot FSF on 3mm-thick A5083P-O aluminum plates at offsetting points from the center of a hole and evaluated the height and volume of cylindrical extrusions to evaluate the deformability distribution under a tool. In addition, forming pressure distribution on the die surface was evaluated by an embedded pressure pin connected with a load sensor. The authors conducted spot FSF on 3mm-thick A5083P-O aluminum plates at offsetting points from the center of a pin as well as deformability tests and evaluated forming pressure compiled from the bearing load of the pin. In the deformability test, the extrusions without offsetting were shorter than the ones with 2mm offset. However, the forming pressure without offsetting was higher than the pressure with 2mm offset. Surface sink of the product without offsetting was observed below the tool probe. This implies that the probe restricts supplement of material volume to the die cavity directly below it, though it effectively extends the deformable material volume.

Point and Extended Defect Interactions in Silicon

ABSTRACTTransient Enhanced Diffusion (TED) is one of the biggest modeling challenges present in predicting scaled technologies. Damage from implantation of dopant ions changes the diffusivities of the dopants and precipitates to form complex extended defects. Developing a quantitative model for the defect behavior during short time, low temperature anneals is a key to explaining TED. The surface can play a defining role in the removal of point defects from the bulk, but there is a lot of controversy over the role and strength of the surface sink for point defects. The controversy will be reviewed, and new experimental results will be presented that investigate the role of the surface on TED.