Optimum design of a servo-controlled breathing regulator for underwater divers

This article deals with the analysis, synthesis and performance evaluation of the flow and dynamic characteristics of the new class of servo-controlled breathing regulators for underwater divers.Emphasis on such a class of regulators has been stimulated by their tremendous potential in extending the dive depth and duration because they reduce the diver breathing effort to a great extent. This would eliminate the unnecessary exhaustion of the diver under such extreme diving conditions and accordingly improve his work efficiency underwater.The study aims at developing rational design procedures and guides that would enable the regulator designers to select the optimal design parameters of this class of regulators. Such design guides are based on the analysis of the flow and dynamic characteristics of the servo-controlled regulator as well as the basic principle of the theory of optimum control.The study presents also experimental evaluation techniques of the dynamic characteristics of this class of regulators in order to provide common quantitative means for comparison with the conventional regulator designs.The presented results emphasize the merits and the potential of the servo-controlled regulators as essential tools of supporting the life of divers underwater.     

A comparative study of the breathing and clearing characteristics of different types of snorkels

This article presents a comparative study of the breathing resistance and clearing characteristics of several types of commercially available snorkels in an attempt to device quantitative means that enable the divers to select the best snorkel and the designers to see the possible directions and modifications necessary for improving the performance of such important life support devices.Two test stands have therefore been built, the first to measure the breathing resistance and the second to monitor the clearing efficiency and speed of some of the commonly used snorkels.The tested snorkels varied from the simple J-type to the sophisticated wrap-around snorkels with convoluted flexible hoses and flared ends.The results obtained show that large diameter snorkels of the wrap-around design with sweeping barrels and flared ends (as the AMF Swimmaster snorkel number 2S55) offer the least breathing resistance. As for the clearing characteristics snorkels with small diameters and of the simple J-type (as the Spanish Aquasub snorkel: The Canarias) or with large diameters and sweeping barrels (as the Power Tuned snorkel of U.S. divers) possess the best clearing figure of merit.     

Mode of formation of the Nile Gorge in northern Egypt: a study by DEM‐SRTM data and GIS analysis

This is an overview of the mode of formation of the Nile Gorge in northern Egypt. It is based on the interpretation of the Shuttle Radar Topography Mission (SRTM) data along with detailed analysis of landsat image, geological map and seismic data. The results show that the current course of the Nile was caused by a differential uplift of two plateaus: Ma'aza, to the east, and Western Desert plateau, to the west of the river. This uplift is caused by dynamic forces resulting from subsurface convection processes. It also contributed to the formation of several drainage systems, basins and structural features. Abundant faults and fractures that are parallel to the Nile Valley on both flanks that are associated with uplift are proven to be contemporaneous with formation of the river. We conclude that understanding of the uplift is crucial to visualizing the Nile course and its geodynamic formation. The information derived from the SRTM data reveals invaluable knowledge in support of the presented remotely sensed geological features. The paper clearly explains the stages of formation of the Nile segments in space and time and structural controls on the path of the Nile River in Egypt. Copyright © 2015 John Wiley & Sons, Ltd.     

A self-heated first stage breathing regulator for underwater divers

This article presents a new class of first stage breathing regulators for underwater divers with built-in self-heating capabilities. In this class of regulators, the energy of the high pressure life support gas is used to heat both the inhaled gases and the regulator core in an attempt to combat problems of cold water diving.The thermal characteristics of this regulator are monitored and compared with those of a conventional regulator under different simulated dive temperatures, breathing frequencies and also under free flow conditions.The obtained results show that the self-heated first stage (SHFS) regulator delivered warm gases and performed successfully in zero°C water while the conventional regulator failed even when equipped with the environmental protection kit.This paper emphasizes the potential of the self-heated regulator as an essential part of cold water diving gear.     

The dynamic characteristics of vortex tube-assisted hyperbaric chambers

Excessive temperature rise during compression inside hyperbaric chambers is a serious source of discomfort for their occupants. In this article a new class of vortex tube-assisted hyperbaric chambers is presented where such temperatures are reduced passively without the need for external power source. The vortex tube is utilized as means for generating the necessary cooling effect as the gases flow from their storage tanks into the chamber.Mathematical and experimental models of the new concept have been developed to study the dynamic and thermal characteristics of the vortex tube-assisted chambers under different conditions. Comparisons between such characteristics and those of unassisted chambers suggest the potential of the vortex tube assist in reducing the temperatures inside the hyperbaric chambers and accordingly the size of the installed cooling systems required for maintaining certain comfortable temperature levels.     

Morphological Variation of the Sea Silverside Odontesthes regia in Regions with Dissimilar Upwelling Intensity along the Humboldt Current System

Ocean Science Journal - We evaluated the influence of areas with dissimilar upwelling intensity along the Humboldt Current System on the morphological variation of the economically important sea...     

A self-heated second stage regulator for underwater divers

This article deals with the development, testing and performance evaluation of a new class of a self-heated breathing regulator for underwater divers.This class of regulators is introduced because of its capability of utilizing the energy of the compressed gas, used in supporting the lives of divers underwater, in heating the inhaled gases as well as in eliminating the problems of regulator freeze-up in cold waters.The paper presents the performance characteristics of the self-heated second stage regulators under different simulated dive temperatures, breathing frequencies and tidal volumes.Comparisons are also presented between the performance of the self-heated regulator and a conventional regulator in order to define the merits and limitations of each type under different dive conditions.The obtained results indicate that the self-heated regulator produced not only warm gases but performed successfully in zero°C waters while the conventional regulator has failed.This paper suggests the potential of the self-heated regulator as viable means for alleviating the problems of cold water diving.     

A compressed gas-powered heating system for underwater divers

This article presents a heating system for divers which is totally powered by the compressed gas used in supporting their lives underwater. The pressure energy stored in the breathing gas, which is conventionally wasted through throttling, is utilized to generate a heating effect by expanding the gas in an optimally designed vortex tube.A mathematical model is presented to predict the generated heating effect at different dive depths and ambient temperatures with air and heliox as breathing mixtures.Comparisons are given between the heating effect developed by the system and those required by the divers when wearing different diving suits and working at various work loads. Those comparisons emphasize the potential of the system as a viable means for heating the divers, their inhaled gases as well as their dive gear in a way that eliminates the complexity and hazards of presently available systems.     

BLOCK ADJUSTMENT WITH ARRAY AND VECTOR PROCESSORS

The paper discusses some hardware and software developments in mainframe computers and their effects on aerial triangulation block adjustment programs. The results of test runs on two modern computers with unconventional architectures are given and comparisons are made with run times on more conventional serial type computers.     

Flow characteristics of exhalation valves of diving regulators

This study presents the flow-resistance characteristics of conventional exhalation valves used in underwater diving regulators. Evaluation of such characteristics is essential to quantifying the effect of the main design parameters of these valves on the diver's exhalation effort.Plain, tapered as well as tapered supported valves of different materials have been considered in this study.Valves seats of different geometrical configurations which varied from the simple multi-circular hole seats to the more imaginative Posiden-like seats have been studied. Triangular, multi-quadrant as well as full diaphragm exhalation valves have also been tested in details.New designs of exhalation valves have also been developed and tested in an attempt to define the optimum configuration as well as the best combination of the valve and its seat that would reduce the exhalation effort to a minimum. Among the considered new designs are the vortex and nozzle-assisted exhaust valves.The obtained results show that full diaphragm exhalation valves offer the least breathing resistance followed by the 13-hole Posiden-like exhalation valve, the nozzle-assisted valves and the vortex-assisted valves. Nonetheless, the 2.9-cm diameter plain, unsupported and untapered valve on the six-triangle seat exhibits flow characteristics that are not too far from the most fancy designs.The obtained results presents design guides, for improving the breathing characteristics of the exhalation valves, which can be extremely important to the designers and manufacturers of diving regulators.