Heatshield material selection for advanced ballistic reentry vehicles

The Performance of staple rayon fiber and AVTEX continuous rayon fiber was evaluated as precursor materials for heatshields. The materials studied were referenced to the IRC FM5055A heatshield materials flown during the past decade. Three different arc jet facilities were used to simulate portions of the reentry environment. The IRC FM5055A and the AVTEX FM5055G, both continuous rayon fiber woven materials having the phenolic impregnant filled with carbon particles were compared. The AVTEX continuous fiber, unfilled material FM5822A was also examined to a limited extent. Test results show that the AVTEX FM5055G material provided a close substitute for the IRC FM5055A material both in terms of thermal protection and roll torque performance

INCORPORATION OF WITHIN-SEASON YIELD GROWTH INTO A MATHEMATICAL PROGRAMMING SUGARCANE HARVEST SCHEDULING MODEL

This study focuses on the development of a optimal harvest scheduling mathematical programming model which incorporates within-season changes in perennial crop yields. Daily crop yield prediction models are estimated econometrically for major commercially grown sugarcane cultivars. This information is incorporated into a farm-level harvest scheduling linear programming model. The harvest scheduling model solves for an optimal daily harvest schedule which maximizes whole farm net returns above harvesting costs. Model results are compared for a commercial sugarcane farm in Louisiana.sugarcane, harvest scheduling, within-season yield growth, Crop Production/Industries,

Ward's Hierarchical Clustering Method: Clustering Criterion and Agglomerative Algorithm

The Ward error sum of squares hierarchical clustering method has been very widely used since its first description by Ward in a 1963 publication. It has also been generalized in various ways. However there are different interpretations in the literature and there are different implementations of the Ward agglomerative algorithm in commonly used software systems, including differing expressions of the agglomerative criterion. Our survey work and case studies will be useful for all those involved in developing software for data analysis using Ward's hierarchical clustering method.Comment: 20 pages, 21 citations, 4 figure

First case of spontaneous rupture of the left ureter in immediate post-partum

The rupture of the ureter during pregnancy is a rare complication and is most frequently observed in the right ureter. We report below the case of a rupture in the left ureter. A 36-year old woman gave birth vaginally to a 3010-g girl without operative vaginal delivery or episiotomy. The following day, the patient exhibited a sudden pain in the left side spreading to the left iliac fossa. An abdominopelvic CT scan was carried out and revealed a flow of contrast agent at the left ureteral lumbar level and a left urinoma. A ureteral stent was inserted on the left side under X-ray control. Six weeks after delivery the ureteral stent was removed. The Uro CT scan allowed us to confirm the total recovery of the left ureter. We have reported below the first case of left rupture treated in a conservative manner with positive and functional clinical progress

Maximizing Economic Returns from Sugarcane Production Through Optimization of Harvest Schedule (Bulletin #868)

This bulletin presents a methodology for the incorporation of within-season sucrose accumulation in sugarcane into an optimal single-season, daily harvest scheduling model at the individual farm level.https://digitalcommons.lsu.edu/agcenter_bulletins/1033/thumbnail.jp

Long-term changes in a zooplankton community revealed by the sediment archive

To reconstruct changes in zooplankton communities in response to past anthropogenic perturbations, one possibility is to use the sedimentary records. We analyzed the sediments at a coastal site in the Northern Baltic Sea to relate changes in the zooplankton community to anthropogenic eutrophication and the invasion of a predatory cladoceran, Cercopagis pengoi. We sampled 30-cm laminated sediment cores and dated the sediment layers back to the 1950s. From each 1-cm layer, we measured eutrophication indicators (delta C-13, delta N-15, TC, TN, TP) and identified and counted zooplankton resting eggs (cladoceran, calanoid copepod, rotifer). In addition, we estimated the abundance of the cladoceran Bosmina (Eubosmina) maritima by counting subfossils (carapaces, headshields, and ephippia) and estimated the experienced stress as the relationship between sexual and asexual reproduction. Using redundancy and variance partitioning analyses, we found similar to 16% of the variation in the zooplankton community to be explained by eutrophication, and 24% of the variation in B. (E.) maritima abundance and reproduction mode to be explained by eutrophication and the introduction of the alien predator. Our results show a long-term shift from calanoid copepods and predatory cladocerans toward small-sized zooplankton species, like rotifers. Furthermore, the results indicate that the invasion of C. pengoi induced a short-term increase in sexual reproduction in B. (E.) maritima. The results indicate that anthropogenic eutrophication since the 1950s has altered the zooplankton community toward smaller species, while the invasion of the predatory cladoceran had only a transitory influence on the community during its expansion phase.Peer reviewe

Systematic evaluation of objective functions for predicting intracellular fluxes in Escherichia coli

To which extent can optimality principles describe the operation of metabolic networks? By explicitly considering experimental errors and in silico alternate optima in flux balance analysis, we systematically evaluate the capacity of 11 objective functions combined with eight adjustable constraints to predict 13C-determined in vivo fluxes in Escherichia coli under six environmental conditions. While no single objective describes the flux states under all conditions, we identified two sets of objectives for biologically meaningful predictions without the need for further, potentially artificial constraints. Unlimited growth on glucose in oxygen or nitrate respiring batch cultures is best described by nonlinear maximization of the ATP yield per flux unit. Under nutrient scarcity in continuous cultures, in contrast, linear maximization of the overall ATP or biomass yields achieved the highest predictive accuracy. Since these particular objectives predict the system behavior without preconditioning of the network structure, the identified optimality principles reflect, to some extent, the evolutionary selection of metabolic network regulation that realizes the various flux states

Effect of the use of a video tutorial in addition to simulation in learning the maneuvers for shoulder dystocia

The development of video tutorials is flourishing and may make it possible to maintain knowledge learned during instruction with simulation. The aim of this study was to assess the effect of adding a video tutorial to a lecture and simulation for learning the maneuvers and protocol for the management of shoulder dystocia. Student midwives and medical students attended a lecture class including instruction about maneuvers and a presentation of an algorithm for the management of shoulder dystocia. They were randomized into two groups. The video group was reminded every two weeks to watch a short tutorial. The control group was reminded to consult the slide show. At the end of two months, they were evaluated by graders. The practice, theory, and global scores of the students in the video group were significantly higher than those of the students in the control group (14.8 vs. 10.4; 5.6 vs. 3.4; and 9.3 vs. 7.0, P<0.001). The scores for the video group improved at the second simulation session, compared with the first (14.8 vs. 9.9; 5.6 vs. 2.9; and 9.3 vs. 7, P<0.001). The addition of a video tutorial improved learning compared to a standard lecture and simulation session alone

Detection of Orbital Debris Collision Risks for the Automated Transfer Vehicle

In this paper, we present a general collision risk assessment method, which has been applied through numerical simulations to the Automated Transfer Vehicle (ATV) case. During ATV ascent towards the International Space Station, close approaches between the ATV and objects of the USSTRACOM catalog will be monitored through collision rosk assessment. Usually, collision risk assessment relies on an exclusion volume or a probability threshold method. Probability methods are more effective than exclusion volumes but require accurate covariance data. In this work, we propose to use a criterion defined by an adaptive exclusion area. This criterion does not require any probability calculation but is more effective than exclusion volume methods as demonstrated by our numerical experiments. The results of these studies, when confirmed and finalized, will be used for the ATV operations