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Underwater Wireless Sensor Networks (UWSNs) provide new opportunities to observe and predict the behavior of aquatic environments. In some applications like target tracking or disaster prevention, sensed data is meaningless without location information. In this paper, we propose a novel 3D centralized, localization scheme for mobile underwater wireless sensor network, named Reverse Localization Scheme or RLS in short. RLS is an event-driven localization method triggered by detector sensors for launching localization process. RLS is suitable for surveillance applications that require very fast reactions to events and could report the location of the occurrence. In this method, mobile sensor nodes report the event toward the surface anchors as soon as they detect it. They do not require waiting to receive location information from anchors. Simulation results confirm that the proposed scheme improves the energy efficiency and reduces significantly localization response time with a proper level of accuracy in terms of mobility model of water currents. Major contributions of this method lie on reducing the numbers of message exchange for localization, saving the energy and decreasing the average localization response time.

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Deviation from vertical path makes drill cuttings to accumulate on the lower side of the wellbore that induces the formation of cuttings bed. Subsequently, relative problems occur while drilling. Excessive torque and drag, difficulties in running casing in hole and accomplishing good cementing jobs and mechanical pipe sticking are few of the classical examples of such problems. Therefore, a comprehensive understanding of influential parameters on hole cleaning seems to be essential. This paper indicates the results of an experimental study that was carried out to evaluate cuttings removal efficiency using three types of drilling fluid. The experimental works were conducted using a 17-feet long opaque flow loop of 2-in. diameter as the test section. For each test, the amount of cuttings transport performance (CTP) was determined from weight measurements. Viscosity was investigated together with other two influential parameters, namely fluid velocity and hole inclination under various flow conditions. It is shown that the increase in drilling fluid viscosity has improved CTP by approximately 8 % at all angles provided the flow regime remained turbulent while velocity was kept constant. However, further increase of viscosity as flow regime was turning into transient or laminar flow, has lessened CTP by a total average of 12 %. It was also revealed that an incremental escalation in hole inclination from 60°to 90°has a positive effect on CTP, i.e., it will be improved up to 40 %. Drilling fluid velocity was found to have significant impact on CTP as it could attain maximum percentage of 98 %.

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