Damage Control Surgery

Objective: The basis of damage control surgery rests on quick control of life-threatening bleeding, injuries, and septic sources in the appropriate patients before restoring their physiological reserves as a first step followed by ensuring of the physiological reserves and control of acidosis, coagulopathy, and hypothermia prior to complementary surgery

The effects of vardenafil and pentoxifylline administration in an animal model of ischemic colitis

OBJECTIVES: Vardenafil enhances dilatation of vascular smooth muscle and inhibits platelet aggregation. The purpose of this study was to evaluate the clinical effects of vardenafil and pentoxifylline administration in an experimental model of ischemic colitis. METHODS: Forty female Wistar albino rats weighing 250-300 g were randomized into five experimental groups (each with n = 8) as follows:1) a sham group subjected to a sham surgical procedure and administered only tap water; 2) a control group subjected to a standardized surgical procedure to induce ischemic colitis and administered only tap water; 3) and 4) treatment groups subjected to surgical induction of ischemic colitis followed by the postoperative administration of 5 mg/kg or 10 mg/kg vardenafil, respectively; and 5) a treatment group subjected to surgical induction of ischemic colitis followed by postoperative administration of pentoxifylline at 50 mg/kg/day per day as a single dose for a 3-day period. All animals were sacrificed at 72 h post-surgery and subjected to relaparotomy. We scored the macroscopically visible damage, measured the ischemic area and scored histopathology to determine the severity of ischemia. Tissue malondialdehyde levels were also quantified. RESULTS: The mean Gomella ischemic areas were 63.3 mm2 in the control group; 3.4 and 9.6 mm2 in the vardenafil 5 and vardenafil 10 groups, respectively; and 3.4 mm2 in the pentoxifylline group (p = 0.0001). The mean malondialdehyde values were 63.7 nmol/g in the control group; 25.3 and 25.6 nmol/g in the vardenafil 5 and vardenafil 10 groups, respectively; and 22.8 nmol/g in the pentoxifylline group (p = 0.0001). CONCLUSION: Our findings indicate that vardenafil and pentoxifylline are effective treatment options in an animal model of ischemic colitis. The positive clinical effects produced by these drugs are likely due to their influence on the hemodynamics associated with vascular smooth muscle and platelet functions

Optimal Angle of Inclination for Fixed Solar Panels/Collectors

In the use of solar energy as a source of renewable energy a practical question is commonly encountered. What is the optimal angle of inclination for fixed solar panels? This is applicable for both arrays of solar photovoltaic (PV) panels as well as for flat plate solar collectors. It is quite common practice to use a couple of rules of thumb that state the following: (a) the panels/collectors should be facing south (for the northern hemisphere locations), and (b) the optimal angle of inclination will be in the range of the latitude of the location . In this paper we discuss a computer program developed to verify (b) for south facing fixed solar panels/collectors. The program developed can generate theoretical solar irradiation available for a given location in the northern hemisphere on a clear day taking into account the attenuation effects in the atmosphere by incorporating the concept of air mass. It can also be used to retrieve solar irradiation data from well established databases such as the National Solar Radiation Data Base (NSRDB) accessible via the National Renewable Energy Laboratory (NREL). Both approaches have been tested and weekly, monthly and annual optimal angles of inclination have been generated for selected locations. This paper will discuss the details of the algorithm and databases used and the results obtained. How this program is going to be used in an undergraduate course titled Alternative Energy Systems and Applications will also be discussed

Kambiz Vafai Analysis of Energy and Momentum Transport for Fluid Flow Through a Porous Bed

This paper presents an analysis for the forced convective flow of a gas through Introduction Packed beds have been used very widely in the chemical industry and for energy storage purposes. Among the common applications are catalytic reactors, absorption and adsorption operations, as well as packed bed (pebble bed or rock pile) heat storage units. Due to their high performance, they are now also being considered for use in a number of applications such as fixed-bed nuclear propulsion systems and spacecraft thermal management systems. Utilization of phase-change material in microencapsulated form as the solid particles of the bed has also proved to be a promising research area. For example, A major part of the studies conducted to date on packed bed applications concentrate on utilizing incompressible fluids, liquid or gas, as the heat transfer medium. In these investigations a constant mass flow rate is assumed at every cross section of the packed bed and therefore there is no need for solving the continuity and momentum equations. The problem reduces to solving the governing energy equations for the solid and fluid phases. For this category of problems the two commonly employed models are the so-called single-phase conductivity and two-phase Schumann models. The main distinction between these two models is that whereas local thermal equilibrium is assumed to prevail in the single-phase model, no such assumption is made in the two-phase model. Therefore the single-phase conductivity model reduces to one governing energy equation, whereas in the two-phase model there are two governing energy equations with each of them possessing a fluid to solid phase heat transfer term. The origin of the two-phase models is the classical Schumann mode

A Computational Method for Determining the Equilibrium Composition and Product Temperature in a LH2/LOX Combustor

In what follows, the model used for combustion of liquid hydrogen (LH2) with liquid oxygen (LOX) using chemical equilibrium assumption, and the novel computational method developed for determining the equilibrium composition and temperature of the combustion products by application of the first and second laws of thermodynamics will be described. The modular FORTRAN code developed as a subroutine that can be incorporated into any flow network code with little effort has been successfully implemented in GFSSP as the preliminary runs indicate. The code provides capability of modeling the heat transfer rate to the coolants for parametric analysis in system design

Wind Energy Assessment Using a Wind Turbine With Dynamic Yaw Control

In conducting the siting analysis of a possible on-shore or off-shore wind farm, computational tools are required to analyze the extensive wind data collected over long periods of time in order to estimate the energy that can be harnessed at that particular location. The major parameters that play a crucial role in this are the wind speed, wind direction, and presence of turbulence in the upcoming wind. However, estimation of the potential for electrical energy generation from wind at a particular site is quite complex and prone to error due to the uncertain nature of the wind. The yaw error, which is the difference between the direction of wind and the normal to the face of the rotor, can reduce the power output of a wind turbine significantly. Zero inertia assumption for the turbine rotor used by multiple assessment tools result in overestimation of the power output. For an accurate estimation of the energy that can be harnessed, the effect of directional change of the wind should be incorporated along with the other obvious parameters such as the wind speed, the effect of landscape and altitude. Most modern utility-scale wind turbines are equipped with yaw motion controller and direction measuring sensors that help change the yaw angle of the wind turbine to adjust for the wind direction. A dynamic control model and the corresponding scheme have to be incorporated in the energy estimation process. A wind energy assessment analysis for a potential off-shore wind farm in Lake Michigan is currently under way. An unmanned marine buoy, equipped with LIDAR-based data acquisition system, is deployed in Lake Michigan and data are measured at six different altitudes starting from 55 m and up to 175 m. As project participants, the authors have been working on developing a versatile, flexible and precise model and software tool to evaluate the potential for electrical energy generation. A MATLAB based program has been developed for this purpose, equipped with the capability of working with different data formats and different time averaged data sets. A dynamic model capable of considering the change in wind direction and adjusting the yaw angle has been developed as a part of the MATLAB program. The dynamic model evaluates the yaw error and implements a scheme for the adjustment of the orientation of the wind turbine in order to provide an accurate estimate of the amount of wind energy that can be converted into electrical energy. The algorithm for this dynamic model and the results obtained are discussed in this paper

A Novel Approach for Modeling Chemical Reaction in Generalized Fluid System Simulation Program

The Generalized Fluid System Simulation Program (GFSSP) is a computer code developed at NASA Marshall Space Flight Center for analyzing steady state and transient flow rates, pressures, temperatures, and concentrations in a complex flow network. The code, which performs system level simulation, can handle compressible and incompressible flows as well as phase change and mixture thermodynamics. Thermodynamic and thermophysical property programs, GASP, WASP and GASPAK provide the necessary data for fluids such as helium, methane, neon, nitrogen, carbon monoxide, oxygen, argon, carbon dioxide, fluorine, hydrogen, water, a hydrogen, isobutane, butane, deuterium, ethane, ethylene, hydrogen sulfide, krypton, propane, xenon, several refrigerants, nitrogen trifluoride and ammonia. The program which was developed out of need for an easy to use system level simulation tool for complex flow networks, has been used for the following purposes to name a few: Space Shuttle Main Engine (SSME) High Pressure Oxidizer Turbopump Secondary Flow Circuits, Axial Thrust Balance of the Fastrac Engine Turbopump, Pressurized Propellant Feed System for the Propulsion Test Article at Stennis Space Center, X-34 Main Propulsion System, X-33 Reaction Control System and Thermal Protection System, and International Space Station Environmental Control and Life Support System design. There has been an increasing demand for implementing a combustion simulation capability into GFSSP in order to increase its system level simulation capability of a liquid rocket propulsion system starting from the propellant tanks up to the thruster nozzle for spacecraft as well as launch vehicles. The present work was undertaken for addressing this need. The chemical equilibrium equations derived from the second law of thermodynamics and the energy conservation equation derived from the first law of thermodynamics are solved simultaneously by a Newton-Raphson method. The numerical scheme was implemented as a User Subroutine in GFSSP