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.     

Estimation of methane fluxes from bottom sediments of Lake Baikal

Methane bubble fluxes in gas flares from bottom sediments in Lake Baikal were estimated for the first time using hydroacoustic methods. Earlier work has demonstrated the occurrence of gas seeps both inside and outside of areas where bottom simulating reflectors were identified in seismic profiles. Fluxes ranged from 14 to 216 tons per year, with the flux for the entire area of the central and southern basins ranging from 1,400 to 2,800 tons per year. Comparison with other water bodies showed that fluxes from the most intensive Baikal flares were similar to those in the Norwegian and Okhotsk seas. Gas hydrates decompose at the lower boundary of the gas hydrate stability zone due to sedimentation. Calculation of the amount of methane produced due to sedimentation gave a total of between 2,600 and 14,000 tons per year for the central and southern basins of the lake. Based on rough estimation, the total flux from shallow- and deep-water gas seeps is similar to the amount of methane produced due to sedimentation. This suggests that gas hydrates possibly occupy much more than 10?% of the pore volume near the base of the gas hydrate stability zone, or that there are other reasons for gas hydrate dissociation and bubble flux from these bottom sediments.     

Fractionation analysis of transport engine-generated soot particles with respect to hygroscopicity

Combustion-derived particles emitted by various transport engines are analyzed with respect to their morphology and composition. Soot particles collected behind an aircraft gas turbine engine combustor, in the diesel engine exhaust pipe, and at the end of ship pipe demonstrate heterogeneous morphological structures and different chemical identities. Individual particle analysis allows the characterization of emitted soot particles into three fractions, namely C-O, C-O-S, and Fe-C-O, with the dominant presence of chain soot agglomerates, irregular internally mixed soot, and particles of distinct morphology, respectively. The influence of oxygen and sulfur concentrations on the ability of soot to uptake water is proposed as a method for categorizing transport engine-generated particles. Categories of hydrophobic and hydrophilic particles within non-hygroscopic soots can be defined based on the amount of water uptake relative to several reference laboratory-made soots comparable to transport engine emissions. This method of characterizing hydrophobic/hydrophilic and hygroscopic soots in combustion emissions will help to determine the potential impacts of the combustion emissions on CCN/IN formation in the atmosphere.     

Vertical Variability of Primary Production and Chlorophyll a in the Kara Sea in the Middle of Summer: Contribution of Subsurface Maxima to the Water Column Values

Oceanology - Spatial and vertical variability of primary production (PP) and Chl a were studied in the framework of the 76th cruise of R/V Akademik Mstislav Keldysh to the Kara Sea from July 7 to...     

Radiation-Geochemical Stability of Bottom Sediments in the Ob and Yenisei Estuaries and Adjacent Shoal Area of the Kara Sea

Oceanology - This paper reports the results of investigations on the radioecological state of bottom sediments of the Ob–Yenisei shoal area and Ob and Yenisei estuaries. Materials were...     

Application of Theorems on Null-Geodesics on The Solar Limb Effect

A direct and more general calculation of the limb effect connected with red-shift observations is obtained. Result agrees completely, in its general form, with that obtained from observations of the solar spectra but with different value for the maximum effect. This revised version was published online in July 2006 with corrections to the Cover Date. This revised version was published online in July 2006 with corrections to the Cover Date.     

Climate change influences on pollinator,forest, and farm interactions across a climate gradient

Improved cookstoves have been identified in Mexico as a key opportunity to advance sustainable local development priorities in disadvantaged regions while mitigating climate change. This paper reviews the Patsari Cookstove Project initiated in 2003 by an NGO, Interdisciplinary Group on Appropriate Rural Technology (GIRA). The project applied an interdisciplinary and participative user-centered approach to disseminate improved cookstoves in rural Mexico, with a special focus on indigenous and poor rural communities. To date, GIRA and the Patsari Network have disseminated thousands of stoves using a “training to trainers” model. Benefits from the project include tangible improvements in users’ health, as well as savings in time and money expended on fuelwood procurement and use. The project has also documented substantive environmental benefits from significant mitigation of greenhouse gas (GHG) emissions associated with traditional open fires. To sustain scaling up efforts over the long-term, two networks have been created: The Patsari Network, which includes several organizations promoting Patsari stoves for household users, and the Tsiri Network, which supports local food security and the empowerment of indigenous women through the promotion of institutional cookstoves. Through appropriately designed and implemented local interventions, the project demonstrates that the goals of advancing sustainable local development in rural areas and climate change mitigation may not be contradictory, and may in fact reinforce one another.