Mathematical models and methods for analyzing flow properties in hydraulic circuits with closed circulation circuits

The article is devoted to the problems of calculating the distribution of flow quality parameters over the elements of the hydraulic system. The main attention is paid to the problem of such a calculation in the presence of closed circulation circuits in the system, when traditional methods and algorithms become ineffective. Mathematical models of the distribution of quality parameters are given, the results of the analysis of their properties in the presence of closed circulation circuits are presented. Against the background of the analysis of the applicability of general mathematical methods for solving the problem, two new methods are proposed based on the special properties of this problem - the “iterative topological” algorithm and the “algebraic-topological” method. Both methods are universal and provide a solution in the presence of closed circulation loops, and in their absence they coincide with the traditional “topological” algorithm.

Budidaya Udang Vannamei (Litopenaeus vannamei) Semiintensif Dengan Metode Sirkulasi Tertutup Untuk Menghindari Serangan Virus [The Semiintensive Culture Of Litopenaeus vannamei By Closed Circulation Method To Prevent Virus Attack]

The failure of vannamei shrimp culture often caused by virus attack, i.e. WSSV, TSV and IMNV. So that it need an alternative method like closed circulation method and probiotic application. Closed circulation is culture method without water circulation where as an additional water will do to change loss water, caused by evaporation and culture waste water. This kinds of probiotic ar Bacillus subtilis, Nitrosomonas, Nitrobacter, Saccaromyces, Rhodobacter and Rhodococcus. The aim of these research are preventing virus attack through closed circulation method and probiotic 2 2application. These culture used two culture ponds (3000 m , density 60 species/m ) and two reservoir ponds 2(2000 m ) for 105 days. The first culture pond (A) produced 2895 kg of vannamei shrimp (size 60, SR 96.5 % and FCR 1.3). The second culture pond (B) produced 3025 kg of vannamei shrimp (size 58, SR 97.4 % and FCR 1.28).

A Hypothesis for the Intensification of Tropical Cyclones under Moderate Vertical Wind Shear

A major open issue in tropical meteorology is how and why some tropical cyclones intensify under moderate vertical wind shear. This study tackles that issue by diagnosing physical processes of tropical cyclone intensification in a moderately sheared environment using a 20-member ensemble of idealized simulations. Consistent with previous studies, the ensemble shows that the onset of intensification largely depends on the timing of vortex tilt reduction and symmetrization of precipitation. A new contribution of this work is a process-based analysis following a shear-induced midtropospheric vortex with its associated precipitation. This analysis shows that tilt reduction and symmetrization precede intensification because those processes are associated with a substantial increase in near-surface vertical mass fluxes and equivalent potential temperature. A vorticity budget demonstrates that the increased near-surface vertical mass fluxes aid intensification via near-surface stretching of absolute vorticity and free-tropospheric tilting of horizontal vorticity. Importantly, tilt reduction happens because of a vortex merger process—not because of advective vortex alignment—that yields a single closed circulation over a deep layer. Vortex merger only happens after the midtropospheric vortex reaches upshear left, where the flow configuration favors near-surface vortex stretching, deep updrafts, and a substantial reduction of low-entropy fluxes. These results lead to the hypothesis that intensification under moderate shear happens if and when a “restructuring” process is completed, after which a closed circulation favors persistent vorticity spinup and recirculating warm, moist air parcels.

Observations and Predictability of a Nondeveloping Tropical Disturbance over the Eastern Atlantic

A strong African easterly wave (AEW) left the West African coast in early September 2014 and operational global numerical forecasts suggested a potential for rapid tropical cyclogenesis of this disturbance in the eastern Atlantic, despite the presence of a large region of dry air northwest of the disturbance. Analysis and in situ observations show that after leaving the coast, the closed circulation associated with the AEW trough was not well aligned vertically, and therefore, low-level or midlevel dry air was advected below or above, respectively, areas of closed circulation. GPS dropwindsonde observations highlight the dry air undercutting the midlevel recirculation region in the southwestern quadrant. This advection of dry air constrains the spatial extent of deep convection within the AEW trough, leading to the vortex decaying. As the column continues to be displaced horizontally, losing vertical alignment, this enables increased horizontal advection of dry air into the system further limiting convective activity. Ensemble forecasts indicate that short-term errors in precipitation rate and vorticity generation can lead to an over intensified and well-aligned vortex, which then interacts less with the unfavorable environment, allowing for further convection and intensification. The stronger vortex provides more favorable conditions for precipitation through a more vertically coherent closed circulation and thus a positive feedback loop is initiated. The short-term forecasts of precipitation were shown to be sensitive to lower-tropospheric moisture anomalies around the AEW trough through ensemble sensitivity analysis from Global Ensemble Forecast System real-time forecasts.