Biology of moderately halophilic aerobic bacteria

The moderately halophilic heterotrophic aerobic bacteria form a diverse group of microorganisms. The property of halophilism is widespread within the bacterial domain. Bacterial halophiles are abundant in environments such as salt lakes, saline soils, and salted food products. Most species keep their intracellular ionic concentrations at low levels while synthesizing or accumulating organic solutes to provide osmotic equilibrium of the cytoplasm with the surrounding medium. Complex mechanisms of adjustment of the intracellular environments and the properties of the cytoplasmic membrane enable rapid adaptation to changes in the salt concentration of the environment. Approaches to the study of genetic processes have recently been developed for several moderate halophiles, opening the way toward an understanding of haloadaptation at the molecular level. The new information obtained is also expected to contribute to the development of novel biotechnological uses for these organisms

The Dynamic Loop Effect on the Mississippi River: Project Design Flood Flow Line

Source: https://erdc-library.erdc.dren.mil/jspui/The unusually high 1973 and 1975 flood seasons on the Mississippi River revealed apparent significant reductions in flood-carrying capacity. In addition, a heretofore unappreciated phenomenon known as loop effect appeared to have a large impact on stage-discharge relations. As a part of a general reanalysis of the design flood flow line, a study was initiated to help quantify the dynamic loop effect. The purpose of the study was to estimate the loop magnitude at the design flood to be added to the separately evaluated steady-state design flood flow line. A previously developed numerical model for calculations of variable stage-discharge relations was used. The study showed that this model could not account for all of the loop magnitude, probably due to flow complexity and model assumptions. An ad hoc method to simulate the total loop was implemented involving double-valued, variable Manning's ? corresponding to the rising or falling phase of the flow hydrographs. The method of simulation suggests a higher channel resistance at falling river stages. Extrapolation to the design flood is based on the assumption of similarity of river behavior to the 1973 flood. This assumption is consistent with the steady flow line computations using river resistance extrapolation from the 1973 flood data to the design flood. The modified model was applied to three representative gaging stations to quantify the loop magnitude along the lower river. Results of the study indicate that the dynamic loop allowance should be as follows: (1.) Vicksburg - 0.9 ft (2.) Helena - 1.0 ft (3.) Baton Rouge - 0.5 ft. In summary, an allowance of approximately 1.0 ft should be added to the flow line from about Helena to Red River Landing. An amount of 0.5 ft should be sufficient from Red River Landing to about Baton Rouge

Ship Navigation Simulation Study, Southwest Pass Entrance, Mississippi River

Source: https://erdc-library.erdc.dren.mil/jspui/Southwest Pass, Mississippi River, is the main deep-draft navigational entrance into the Mississippi River and provides ocean access to the Ports of New Orleans and Baton Rouge, as well as other terminals servicing the many industries along the lower river. The pre-project channel was authorized at 600 ft wide and 40 ft deep, and proposed to be deepened to 45 ft to accommodate greater inbound tanker ships and outbound bulk grain carriers. The purpose of navigation ship simulation study was to determine the required channel width in the Southwest Pass to provide safe and efficient ship navigation, consistent with the minimum width to reduce dredging. To optimize the channel width, the then-existing charmel was simulated and the results compared with several alternate channel widths including 600, 675, and 750 ft. The study included Mississippi River flows including a high flow of 1,300,000 cfs and a low of 640,000 cfs to bracket the normally expected range of velocities. Current velocities were developed using the TABS modeling systems. Only the entrance area of the Southwest Pass region was simulated and studied. Pilots from the Louisiana Bar Pilots Association participated in the simulation validation and formal pilot testing of the channel alternatives. Tankers of 763-ft length and 125-ft beam loaded to 39-ft draft were used in the existing channel, and tankers of 840-ft length, 138-ft beam, and 44-ft draft were used in the proposed deepened entrance channel. Test results for all piloted simulations were analyzed and included ship track plots and statistical analysis of key ship control parameters, such as ship rudder usage, ship speed, rate of turn, channel edge clearance, etc. The simulation test results showed that the larger design ship will be able to safely navigate through the Southwest Pass entrance into the Mississippi River. Based on the study, it was recommended that the entrance channel width be increased from 600 ft to 700 ft for a short distance of about 3,000 ft on the western edge of the entrance channel

Predicting Construction Effects by Tidal Modeling

Source: https://erdc-library.erdc.dren.mil/jspui/Tidal modeling is divided into two areas: physical scale modeling and mathematical modeling. Physical modeling entails developing, constructing, verifying, and testing a scale model of a prototype. Mathematical modeling entails the same steps for a set of mathematical and/or logical expressions whose solution, usually on a digital computer, yields the desired parameters. The modeling technique and solution method for a specific problem are determined by the problem itself, the type and precision of desired results, and available personnel and physical resources. Three specific applications of physical models are discussed: a study of the feasibility of renovating and maintaining three dikes in Delaware Estuary, a study of flushing characteristics of San Diego Bay with various second entrance plans, and a study of salinity intrusion in Delaware Estuary. Mathematical models are discussed, with emphasis on mathematical models for predicting one- and two-dimensional tidal flows. Specific examples are the Chesapeake and Delaware Canal and a general surge study at WES. Physical and mathematical modeling techniques each have certain advantages. Extensive employment of both techniques at WES shows conclusively that complementary use to resolve different aspects of a comprehensive tidal problem usually provides optimum results

Ship Navigation Simulation Study, Port Jersey Channel, Bayonne, New Jersey. Volume 1: Main Text

Source: https://erdc-library.erdc.dren.mil/jspui/The Port Jersey Channel, Bayonne, NJ, is part of the New York Harbor complex, the leading port on the east coast of the United States. It is one of several channels branching off to the left from the main Anchorage Channel south of the Statue of Liberty. The Port Authority of New York and New Jersey is developing the channel for containership terminals. The existing channel is 35 ft deep below MLW and approximately 750 ft wide with a 1,200-ft turning basin at the end. The proposed improvements include deepening to 41 ft with a channel width of 300 ft. The purpose of the simulation study was to determine the effect of deepening the channel and to aid in design of the dimensions and alignment of the recommended channel. The ship simulation study was conducted by local tug pilots on the simulator and used tidal current data from a mathematical model using the TABS-2 modeling system. Two containership models loaded to 35- and 38-ft draft were used in the existing and proposed channel test scenarios, respectively. Channel widths tested included the existing channel and widths of 250, 300, 370, and 440 ft. Test results used to evaluate the alternative channel plans included pilot ratings, composite ship track plot results, and statistical analysis of key ship navigation parameters, such as rudder angles, ship speed, ship heading, drift angles, etc. The study results are contained in a set of channel design recommendations as follows: (A.) Based on the simulation results, the nominal recommended channel width should be 370 ft. (B.) The channel entrance from the Anchorage Channel should be increased in width starting at 1,700 ft wide and flaring down to 370 ft. (C.) Additional channel width should be provided for ship maneuvering in and out of the turning basin at the far end of the channel. (D.) Enlarging the size of the turning basin to 1,300-ft diameter should be considered. (E.) If the increased channel size is cost prohibitive, consideration of limiting operations during high tidal crosscurrents and winds should be contemplated. (F.) Pilot training on a simulator may also help in improving ship control performance and overcome to some degree the inability to widen the channels because of high costs

Feasibility Study of a Numerical Tow Model

Source: https://erdc-library.erdc.dren.mil/jspui/The objective of the study described in this report was to explore the feasibility of developing a numerical hydrodynamic model of a typical push towboat-barge combination for use in engineering planning and design studies. Such a model might be used to simulate tow movements in restricted waterways in critical river reaches such as bends, bridges, and near navigation locks and dams to determine the adequacy and/or economic efficiency of channel designs. A literature search was conducted and it was found that no information was available at the beginning of this study on numerical models of tow hydrodynamics or on towing tank or prototype tests of the maneuverability of tows. During the course of the study several numerical models did become available and further research in this area was initiated by the U.S. Coast Guard Research and Development office. This work is described herein. Since no information was available for the development or testing of a numerical tow maneuvering model, a series of measurements were made of radio-controlled scale model tows used in physical model studies at the Waterways Experiment Station as they executed standard ship hydrodynamic maneuvers. Data from these measurements and computations were used to determine estimates of hydrodynamic coefficients of a linear model of ship maneuverability. It was found that it is feasible to predict tow maneuvers using a numerical model of tow maneuverability; however, additional measurements of tow response characteristics are required before a model that would be useful in engineering studies can be developed. Comparisons of such a model with recent measurements of full-scale tow maneuvers could demonstrate the validity of this model

Enlargement of the Chesapeake and Delaware Canal: Hydraulic and Mathematical Model Investigation

Source: https://erdc-library.erdc.dren.mil/jspui/Enlargement of the sea-level C&D Canal connecting Chesapeake Bay and Delaware River from 27 by 250 ft to 35 by 450 ft, undertaken in 1954, was essentially complete by 1970 except for about a 2-mile reach at the Delaware River end. Concern about effects of the enlargement on the environmental and biological systems led to the decision to leave the unimproved reach intact, pending completion of extensive environmental studies. The study program included field measurements, physical and mathematical model studies, and ecological studies. This report is concerned with the model studies. The existing Delaware River model was extended to include the 27-by 250-ft C&D Canal and Elk River and the propagation of tides and currents in the addition was verified. Tides, currents, salinities, and discharges were then measured for various head differentials across the canal. The canal was first enlarged to existing conditions (35 by 450 ft, except for the unimproved reach at the Delaware end) and subsequently to project conditions and comparative measurements were made. The critical phenomenon affecting flow in the canal is head differential (?H) across the canal produced by Chesapeake Bay tides at the western end and Delaware River tides at the eastern end. The canal is a very dynamic system and can experience large ?H changes daily. Net flow is toward the lower tide level and enlargement from 27 by 250ft to August 1972 conditions caused net flow to be increased by a factor of about 4.8 and completion of enlargement will cause additional increases. Dye dispersion tests were made for 27 by 250 ft and completed canal conditions and a mean ?H. An existing numerical model based on the one-dimensional unsteady flow equations was used for initial studies concerning net flow changes due to the enlargement. A relatively simple numerical model was developed, tested against known analytical solutions, and applied to show expected salinity changes after enlargement and a reversed salinity gradient near the eastern end of the canal in agreement with field and physical model measurements. _x000D_ _x000D_ NOTE: This file is large. Allow your browser several minutes to download the file

Model Study of a Flood-control Pumping Station at the Charles River Dam

Prepared under contract with the Metropolitan District Commission of the Commonwealth of Massachusetts.This report describes the design, construction and testing of a Froudian model of a proposed 8400-cfs capacity pumping station, Site restrictions require that the flow approach the high specific-speed pumps asymmetrically from an existing ship lock through the Charles River Dam (Boston, Massachusetts). The model included a portion of the Charles River Basin, the existing navigation lock and the pump forebay at the exit of the lock. A single recirculating pump and a suction manifold was used in the model to withdraw water from the forebay through six intakes simulating the prototype pumping station. Flow patterns were obtained by photographs of floating confetti and subsurface streamers. Water surface measurements were made with a point gage read through a surveyor's level. The majority of tests were run with the maximum design discharge and the minimum basin pumping elevation. This provided the most severe forebay conditions of high velocity and low intake submergence. Tests were made to investigate: (1) the improvement of flow conditions at the entrance to the lock; (2) the performance of a single intake in uniform approach flow; and (3) the performance of several forebay and pumping station arrangements. The tests showed that: (1) an 18 ft diameter semi-cylindrical pier was needed at the lock entrance to reduce flow contraction and entrance loss; (2) the intake performed very well when the approach flow was uniform; and (3) the most satisfactory forebay arrangement, within the design restrictions imposed by the site, was with equal lengths of intake chambers. The center line of the pumps and the straight portion of the intake chamber walls were deflected 200 toward the approach flow. The. straight portion of the intake chamber walls were 51 ft in length and thence curved upstream in a circular arc. The circular arc terminated six ft from the lock line and the chord of the are forced an angle of 400 with the line of the lock. Vertical struts placed behind the intakes retarded circulation in the intake chambers and improved the flow into the intakes