Performance prediction evaluation of ceramic materials in point-focusing solar receivers

A performance prediction was adapted to evaluate the use of ceramic materials in solar receivers for point focusing distributed applications. System requirements were determined including the receiver operating environment and system operating parameters for various engine types. Preliminary receiver designs were evolved from these system requirements. Specific receiver designs were then evaluated to determine material functional requirements

Dust Susceptibility at Mine Tailings Impoundments: Thermal Remote Sensing for Dust Susceptibility Characterization and Biological Soil Crusts for Dust Susceptibility Reduction

Mining operations produce massive volumes of mine tailings, which are deposited as slurry into permanent tailings impoundments. An important and heavily regulated environmental hazard associated with mine tailings impoundments is fugitive dust emissions. Wind erosion of mine tailings impoundments and the resulting dusting events, especially those caused by cold weather dusting, remain an on-going challenge for the mining industry. The overall goal of this research was to develop and evaluate effective, economical, and sustainable solutions to two major issues facing mine tailings impoundments with regards to dusting: (1) dust monitoring/detection and (2) dust reduction/prevention. Specifically, the research studied iron mine tailings and used (1) laboratory and field testing to assess the utility of thermal remote sensing techniques for dust monitoring, and (2) laboratory testing to assess the ability of biological soil crusts to reduce dust emissions due to cold weather dusting. A laboratory model was developed to use thermal remote sensing and other atmospheric variables to predict surface moisture content and strength of iron mine tailings. Though this relationship was not found to be directly applicable to field remote sensing, this research suggests that a model could be developed using field data to predict surface moisture content using thermal remote sensing, which would be a useful tool for tailings impoundment managers to employ for dust emissions detection. Additionally, a method was developed and validated that exposed laboratory tailings sample to freezing and sublimation conditions that are representative of those experienced at tailings impoundments located in cold-weather climates, and the dust emissions and strength of these tailings samples was characterized using wind tunnel and ball drop testing. Lastly, biological soil crusts originating from locally-sourced organisms were grown on laboratory tailings samples, and when exposed to freezing/sublimation and tested with wind tunnel and ball drop testing, the biological soil crusts were found to provide resistance to wind erosion and increased surface strength. These results are important, both for the understanding of dust emissions and potential dust mitigation treatments for tailings impoundments, and also for broader issues of wind erosion and dust emissions of soil both globally and on other planets

Fracture mechanics of cellular glass

The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solr concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses

‘I am That Very Witch’: On The Witch, Feminism, and Not Surviving Patriarchy

While contemporary discussions about witchcraft include reinterpretations and feminist reclamations, early modern accusations contained no such complexity. It is this historical witch as misogynist nightmare that the film, The Witch: A New England Folktale (2015), expresses so effectively. Within the film, the very patriarchal structures that decry witchcraft – the Puritan church from which the family exiles itself, the male headship to which the parents so desperately cling, the insistence, in the face of repeated failure, on the viability of the isolated nuclear family unit – are the same structures that inevitably foreclose the options of the lead character, Thomasin

Hyperoxia in extreme hemodilution

Intraoperative surgical blood loss is initially replaced by infusion of red cell-free, cristalloidal or colloidal solutions. When normovolemia is maintained the ensuing dilutional anemia is compensated by an increase of cardiac output and of arterial oxygen extraction. In the ideal case, a surgical blood loss can entirely be `bridged' without transfusion by intraciperative normovolemic hemodilution. However major blood loss results in extreme hemodilution and the transfusion of red blood cells may finally become necessary to increase arterial oxygen content and to preserve tissue oxygenation. When transfusion has to be started before surgical control of bleeding has been achieved, parts of the red blood cells transfused will get lost, thereby increasing intraoperative transfusion needs. Beside red blood cell transfusion, arterial oxygen content can be rapidly increased by ventilating the patient with 100% oxygen (hyperoxic ventilation), thus enhancing the amount of physically dissolved oxygen in plasma (hyperoxia). In experimental and clinical studies hyperoxic ventilation has emerged as a simple, safe and effective intervention to enlarge the margin of safety for hemodynamic compensation and tissue oxygenation in hemodiluted subjects experiencing major bleeding. The hyperoxia-associated microcirculatory dysregulation and impaired tissue oxygenation known to take place in the presence of a physiologic hemoglobin concentration are not encountered in hemodiluted subjects. Hyperoxic hemodilution i.e. the combination of intraoperative extreme hemodilution and hyperoxic ventilation may therefore be considered a cost-effective, safe and efficient supplement to reduce allogeneic transfusion during surgical interventions associated with high blood losses. The vast majority of the experimental and clinical investigations this new concept is based on was initiated and performed under the guidance of Prof. Konrad Messmer. Copyright (C) 2002 S. Karger AG, Basel

Black Panther as Spirit Trip

This is one of a series of film reviews of Black Panther (2018), directed by Ryan Coogler. This review analyzes engagement with the movie as a religious experience and considers some political implications of both its storyline and reception. In particular, the piece focuses on constructions of race, especially in relationship to Africa and African Americans, as well as practical tensions around commodifying dissent

A STUDY OF THE IMPACTS OF FREEZE-THAW ON CLIFF RECESSION AT THE CALVERT CLIFFS IN CALVERT COUNTY, MARYLAND

The Calvert Cliffs, which form much of the western coastline of the Chesapeake Bay in Calvert County, Maryland, are actively eroding and destabilizing, resulting in a critical situation for many homes in close proximity to the slope\u27s crest. Past studies have identified that where waves directly interact with the toe of the slope, wave action controls cliff recession; however, where waves do not regularly interact with the slope toe, the past work identified that freeze-thaw controls recession. This study investigated the validity of this second claim by analyzing the recession rate and freeze-thaw behavior of six study sites along the Calvert Cliffs that are not directly affected by waves. While waves do remove failed material from the toe, in these regions freeze-thaw is believed to be the dominant factor driving recession at the Calvert Cliffs. Past recession rates were calculated using historical aerial photographs and were analyzed together with a number of other variables selected to represent the freeze-thaw behavior of the Calvert Cliffs. The investigation studied sixteen independent variables and found that over 65% of recession at these study sites can be represented by the following five variables: (1) cliff face direction, (2 and 3) the percent of total cliff height composed of soil with freeze-thaw susceptibility F4 and F2, (4) the number of freeze-thaw cycles, and (5) the weighted shear strength. Future mitigation techniques at these sites should focus on addressing these variables and might include vegetation or addressing the presence of water along the face of the slope. Unmitigated, the Calvert Cliffs will continue to recede until a stable slope angle is reached and maintained

Chaos - No randomness in cardiac physiology

Struktur telinga manusia memiliki ciri yang stabil dan dapat diandalkan dibandingkan dengan wajah, karena struktur telinga tidak mengalami Perubahan secara proporsional pada peningkatan usia. Penelitian ini menggunakan ekstraksi ciri Zernike moment invariants (ZMI) untuk menentukan karakteristik daun telinga, sedangkan pengenalan telinga menggunakan Jaringan Syaraf Propagasi Balik (JSPB). Hasil eksperimen menunjukkan akurasi pengenalan telinga mencapai sebesar 96,66%

Searching the ideal inhaled vasodilator: From nitric oxide to prostacyclin

Today, the technique to directly administer vasodilators via the airway to treat pulmonary hypertension and to improve pulmonary gas exchange is widely accepted among clinicians. The flood of scientific work focussing on this new therapeutic concept had been initiated by a fundamental new observation by Pepke-Zaba {[}1] and Frostell in 1991 {[}2]: Both scientists reported, that inhalation of exogenous nitric oxide (NO) gas selectively dilates pulmonary vessels without a concomittant systemic vasodilation. No more than another decade ago NO was identified as an important endogenous vasodilator {[}3] while having merely been regarded an environmental pollutant before that time. Although inhaled NO proved to be efficacious, alternatives were sought-after due to NO's potential side-effects. In search for the ideal inhaled vasodilator another group of endogenous mediators - the prostanoids - came into the focus of interest. The evidence for safety and efficacy of inhaled prostanoids is - among a lot of other valuable work - based on a series of experimental and clinical investigations that have been performed or designed at the Institute for Surgical Research under the guidance and mentorship of Prof. Dr. med. Dr. h.c. mult. K. Messmer {[}4-19]. In the following, the current and newly emerging clinical applications of inhaled prostanoids and the experimental data which they are based on, will be reviewed. Copyright (C) 2002 S. Karger AG, Basel