The application of the relaxation method to the solution of problems involving the flow of gases through porous media

The purpose of this investigation is to determine the feasibility of applying the relaxation method of mathematical analysis to the solution of problems involving the flow of gases through porous media. The relaxation method was first applied to two-dimensional problems by Christopherson and Southwell, who applied it to problems in stress analysis. It was later applied to steady-state heat conduction problems by H. W. Emmons and to steady-state flow of incompressible liquids by A. A. Zwierschowski. The solutions of problems involving the flow of gases through porous media is difficult for all but the simplest boundary conditions, and impractical for many conditions, when the usual analytical means are employed. Consequently, the need for alternative methods of solution is evident --Preface, page ii-iii

Sensitive detection of methane at 3.3 μm using an integrating sphere and interband cascade laser

Detection of methane at 3.3μm using a DFB Interband Cascade Laser and gold coated integrating sphere is performed. A 10cm diameter sphere with effective path length of 54.5cm was adapted for use as a gas cell. A comparison between this system and one using a 25cm path length single-pass gas cell is made using direct TDLS and methane concentrations between 0 and 1000 ppm. Initial investigations suggest a limit of detection of 1.0ppm for the integrating sphere and 2.2ppm for the single pass gas cell. The system has potential applications in challenging or industrial environments subject to high levels of vibration

Water Quality Sampling, Analysis and Annual Load Determinations for TSS, Nitrogen and Phosphorus at the Washington County Road 195 Bridge on the West Fork of the White River

A water quality sampling station was installed at the Washington County road 195 bridge on the West Fork of the White River just above the confluence of the three main forks of the Upper White River in December 2001. The Quality Assurance Project Plan (QAPP) was approved by EPA Region six on March 2002 and sampling was begun at that time. This station is coordinated with a USGS gauging station at the same location. This station was instrumented to collect samples at sufficient intervals across the hydrograph to accurately estimate the flux of total suspended solids, nitrogen and phosphorus into the upper end of Beaver Lake from the West Fork of the White River. The West Fork is listed on Arkansas\u27 1998 303d list as impaired from sediment. The Upper White was designated as the states highest priority watershed in the 1999 Unified Watershed Assessment. Accurate determination of stream nutrients and sediment is critical for future determinations of TMDLs, effectiveness of best management practices and trends in water quality

Aluminophosphate molecular sieves comprised of hydrated triple crankshaft chains

We report the first synthesis of pure aluminophosphate hydrate H2 (AlPO4-H2) and its structure; AlPO4-H2 is constructed exclusively from a hydrated chain building unit that also builds the 18-ring VPI-5 structure and has one-dimensional channels circumscribed by highly elliptical rings consisting often oxygen atoms, implications from the existence of this building unit for the synthesis of novel aluminophosphate molecular sieves and for the synthesis of aluminosilicate and silicate analogues of AlPO4-H2 and VPI-5 are discussed

Insect Problems that Develop on Alfalfa Following Treatment with Certain Insecticides

Author Institution: Departments of Entomology and Agronomy, Purdue University Agricultural Experiment Station, Lafayette, Indian

Hydrogeological and Hydrochemical Connection Between the Decatur City Spring and Crystal Lake, Benton County, Arkansas

Arkansas is ranked nationally in the production of broilers, laying hens, turkey, swine and beef cattle. These animals produce large volumes of waste, which are spread on pasture land as a method of disposal, as well as a source of fertilizer, resulting in nonpoint source contamination of surface water and ground water. One area of concern includes the Decatur City Spring, which provides municipal water for the city of Decatur. A total of eight sites in the surrounding area were monitored routinely for water quality parameters, including pH, specific conductance, and nitrate-nitrogen. Water temperature and spring and lake stage were also recorded. Crystal Lake (site 7), an impoundment of Wolf Creek (site 4) is south and upstream from the Decatur City Spring (site 3). It has been proposed that the city spring and lake are hydrogeologically connected. Additionally, there are two springs, (sites 5 and 6) both northwest and downstream of the lake, below the dam, that provide most of the flow to Wolf Creek. Spring site 1 is downstream from Decatur City Spring on Wolf Creek. Results indicate relatively low, but consistent nitrate concentrations for sites 7 (0.7-1.4 mg/L), 5 (0.4-1.0 mg/L) and 6 (0.2-0.6 mg/L), which are the lake and two springs below it, respectively. These consistent concentrations, as well as the similar periodicities, suggest an association between these three sites. Higher nitrate concentrations are exhibited for sites 3 (2.4-3.0 mg/L) and 1 (2.4-2.9 mg/L), which are the city spring and the spring north of it. There is also correlation in the periodicity of these two sites indicating a relationship between them. Based on similar fluctuations in the hydrochemical data, it can be concluded that Crystal Lake and Decatur Spring are hydrogeologically related. Water flows from Crystal Lake to the two springs below the dam. These springs feed Wolf Creek which is then connected to Decatur Spring via a losing segment just above the spring, hydrogeologically connecting Decatur Spring to Crystal Lake

The role of coach-athlete relationship quality in team sport athletes’ psychophysiological exhaustion: implications for physical and cognitive performance

The present study aimed to examine associations between the quality of the coach-athlete relationship and athlete exhaustion by assessing physiological and cognitive consequences. Male and female athletes (N = 82) representing seven teams across four different sports, participated in a quasi-experimental study measuring physical performance on a 5-meter multiple shuttle test, followed by a Stroop test to assess cognitive performance. Participants provided saliva samples measuring cortisol as a biomarker of acute stress response and completed questionnaires measuring exhaustion, and coach-athlete relationship quality. Structural equation modelling revealed a positive relationship between the quality of the coach-athlete relationship and Stroop performance, and negative relationships between the quality of the coach-athlete relationship and cortisol responses to high-intensity exercise, cognitive testing, and exhaustion. The study supports previous research on socio-cognitive correlates of athlete exhaustion by highlighting associations with the quality of the coach-athlete relationship

Model Validation of an RSRM Transporter Through Full-scale Operational and Modal Testing

The Reusable Solid Rocket Motor (RSRM) segments, which are part of the current Space Shuttle system and will provide the first stage of the Ares launch vehicle, must be transported from their manufacturing facility in Promontory, Utah, to a railhead in Corinne, Utah. This approximately 25-mile trip on secondary paved roads is accomplished using a special transporter system which lifts and conveys each individual segment. ATK Launch Systems (ATK) has recently obtained a new set of these transporters from Scheuerle, a company in Germany. The transporter is a 96-wheel, dual tractor vehicle that supports the payload via a hydraulic suspension. Since this system is a different design than was previously used, computer modeling with validation via test is required to ensure that the environment to which the segment is exposed is not too severe for this space-critical hardware. Accurate prediction of the loads imparted to the rocket motor is essential in order to prevent damage to the segment. To develop and validate a finite element model capable of such accurate predictions, ATA Engineering, Inc., teamed with ATK to perform a modal survey of the transport system, including a forward RSRM segment. A set of electrodynamic shakers was placed around the transporter at locations capable of exciting the transporter vehicle dynamics. Forces from the shakers with varying phase combinations were applied using sinusoidal sweep excitation. The relative phase of the shaker forcing functions was adjusted to match the shape characteristics of each of several target modes, thereby customizing each sweep run for exciting a particular mode. The resulting frequency response functions (FRF) from this series of sine sweeps allowed identification of all target modes and other higher-order modes, allowing good comparison to the finite element model. Furthermore, the survey-derived modal frequencies were correlated with peak frequencies observed during road-going operating tests. This correlation enabled verification of the most significant modes contributing to real-world loading of the motor segment under transport. After traditional model updating, dynamic simulation of the transportation environment was compared to the measured operating data to provided further validation of the analysis model. KEYWORDS Validation, correlation, modal test, rocket motor, transporte

A Framework for Relating the Structures and Recovery Statistics in Pressure Time-Series Surveys for Dust Devils

Dust devils are likely the dominant source of dust for the martian atmosphere, but the amount and frequency of dust-lifting depend on the statistical distribution of dust devil parameters. Dust devils exhibit pressure perturbations and, if they pass near a barometric sensor, they may register as a discernible dip in a pressure time-series. Leveraging this fact, several surveys using barometric sensors on landed spacecraft have revealed dust devil structures and occurrence rates. However powerful they are, though, such surveys suffer from non-trivial biases that skew the inferred dust devil properties. For example, such surveys are most sensitive to dust devils with the widest and deepest pressure profiles, but the recovered profiles will be distorted, broader and shallow than the actual profiles. In addition, such surveys often do not provide wind speed measurements alongside the pressure time series, and so the durations of the dust devil signals in the time series cannot be directly converted to profile widths. Fortunately, simple statistical and geometric considerations can de-bias these surveys, allowing conversion of the duration of dust devil signals into physical widths, given only a distribution of likely translation velocities, and the recovery of the underlying distributions of physical parameters. In this study, we develop a scheme for de-biasing such surveys. Applying our model to an in-situ survey using data from the Phoenix lander suggests a larger dust flux and a dust devil occurrence rate about ten times larger than previously inferred. Comparing our results to dust devil track surveys suggests only about one in five low-pressure cells lifts sufficient dust to leave a visible track