1,067 research outputs found
The Lunar Exosphere: Spatial and Temporal Variations of Sodium and Potassium Emissions from November 2013 to May 2014
I apply high resolution spectroscopy to investigate the lunar exosphere by measuring sodium and potassium spectral line profiles to determine spatial and temporal variations in exospheric effective temperatures and velocities. Observations were made from the National Solar Observatory (MMP) at Kitt Peak, Arizona from November 2013 to May 2014, with the exception of March 2014. Data collection was centered of full moon and spanned several nights with lunar phase angle coverage ranging from 65.6° (waxing) to 78.7° (waning). Observations were concurrent with the NASA LADEE mission science and instrument testing phases. We used a dial etalon Fabry-Perot spectrometer with a resolving power of 180,000 (1.7 km s-1) to measure the line widths and radial velocity shifts to the sodium D2 (5889.9506 Å) and potassium D1 (7698.9646 Å) emission lines. The instrument\u27s three arcmin field of view (~336 km) was positioned at several locations off the lunar limb in each of the four cardinal directions. Only data taken up to 28 seconds in time are presented ad discussed in this thesis.
The sodium line widths were mostly symmetric for both waxing and waning phase angles, with line widths being approximately constant at phase angles larger than 40°. The line widths, and thus line width derived effective temperatures, were largest during magnetotial passage (phase angle 0 - 40°). The line widths outside of the magnetotial (phase angle \u3e 40°) were 1.5 -2.0km s-1 (~ 1100 - 1500 K) while the line widths during full Moon (phase angle ~ 6°) increased to ~ 4 km s-1 (~ 8000 K). The selenographic east limb was hotter than the selecographic west limb, resulting from either location of the role plasma sheet ions play in priming the lunar surface. While line width derived temperatures are indicative of an energetic source such as PSD, the large line widths during full Moon could be due to an observed red shift in velocities due to looking down the extended sodium tail.
Observed potassium line widths are much higher (~ 50%) during waxing phase than waning phase at the phase angles \u3e40°. The Potassium temperatures pre-magnetotial passages are ~ 1000K and post-magnetotial passage are ~ 2000K. Potassium is not detected during full Moon period. The potassium relative intensities for the equatorial regions are similar. The brightest observed limb region was off the Aristarchus crater, which is located near the KREEP region
Setting Constraints on the Lunar Exosphere: A Comprehensive Analysis of Velocity Resolved Sodium and Potassium Line Profile Measurements
This dissertation outlines and presents the most comprehensive set of velocity-resolved measurements of sodium D2 (5889.9509 Å) lines taken over multiple lunations spanning seven years (2011 – 2017). These data are used to study the morphology and dynamics of the lunar exosphere. Additionally, potassium D1 (7698.9646 Å) is used as a complement to sodium. The two species approach, with sodium being the main attraction, provides constraints on the critical drivers of the lunar exosphere. Observations were made at the National Solar Observatory McMath – Pierce Telescope, Kitt Peak, Arizona where I personally collected both sodium and potassium data over about a dozen observing runs. This work builds on the initial velocity resolved measurement analysis of sodium by Mierkiewicz et al. (2014) and includes the sodium analysis of Kuruppuaratchi et al. (2018), and potassium analysis of Rosborough et al. (2019). This work is divided into an analysis of exospheric responses as a function of phase angle (temporal) and an analysis of exospheric responses as a function of latitude and altitude (spatial). Sodium results suggest that photon stimulated desorption (PSD) is the major source mechanism for the lunar sodium exosphere near subsolar points while contributions from charged particle sputtering and micrometeoroid impact vaporization are more important near the dawn and dusk terminators. For potassium, the exosphere exhibits dawn-dusk asymmetry because of impact vaporization and a connection to the surface abundance of potassium. A two species study investigating the response of the exosphere to micrometeoroid impacts shows that sodium appears to have a smooth, gradual response to meteor activity, while potassium appears to have a short-term but significant response. Potassium is found to track closely with surface abundance tied to the regions on the Moon where there are known abundances of potassium (KREEP regions). The spatial study is performed keeping in mind prior works that speculated the possible contribution of plasma sheet ions in the response of the exosphere during magnetotail passage. A large part of this work is focused on the analysis of sodium and potassium based on the near lunar plasma environment: (i.e., solar wind, magnetosheath, and magnetotail) as a function of latitude. Sodium exospheric temperatures and relative intensities indicate that the relative importance of source processes vary depending on the near lunar plasma environment. Potassium, on the other hand, hints at being modulated by micrometeorite impact vaporization throughout all plasma regions. Potassium also shows enhancements in brightness around latitudes where KREEP regions are. Sodium shows some indication of surface enhancement since relative intensity data tend to peak at low-mid latitudes in both North and South regions. Sodium temperatures also show an increase from low to high latitudes. A closer look at the amount of time the Moon spent interacting with the plasma sheet revealed that sodium temperatures showed a positive correlation with time spent in the plasma sheet. Sodium intensities however did not seem to respond as well. The radial dependence of the sodium exosphere indicated that linewidths narrow as a function of altitude. Analysis of these velocity resolved observations from this unique dataset, taken over multiple lunations and years as a function of latitude, altitude, and phase, has helped define baseline and variable conditions of the lunar exosphere - thereby making important contributions towards the study of the near space environment of the Moon which is not only important for testing theoretical models of Surface Bounded Exospheres (SBEs) but also for understanding the atmosphere – surface interactions that will affect human exploration
Pengaruh Bahan Water Repellent Terhadap Morfologi Dan Sifat-sifat Fisika Pada Pembuatan Kulit Atasan Sepatu Ramah Lingkungan
The term of eco-friendly leather can be interpreted as chrome-free tanned leather. Recently, almost 80% of leather is tanned using chrome tanning agent because of the ease in processing and excellence of the physical properties. Nevertheless, people nowadays want an eco-friendly leather product. Vegetable tanning materials can be said as eco-friendly tanning material because their waste degrades easily. One of the weaknesses in the use of vegetable tanning is a high water absorption capability. In this research used a water repellent material that has the properties to suppress the ability of water absorption. The purpose of the research was to determine the effect of water repellent on physical properties and morphology of leather tanned by vegetable tanning materials. Because one of the weaknesses in the vegetable tanning is its high water absorption capability, in this research, water repellent was used and varied by 5; 7.5; 10; 12.5; and 15% . Physical properties obtained were compared with analysis of variance with the significance level of 95%. The water repellent increased from 5% to 15%. The results showed a decrease in water absorption capability from 77.6% to 65.39%, tearing strength from 41.64 to 20.05 kg/cm, tensile strength from 227.10 to 163.53 kg/cm2, and elongation at break from 57.11 to 49.68%, strong swelling and WVA have no significant changes, while for WVP, the maximum use of water repellent at 12.5%. SEM results indicate the presence of a thin layer on the leather fiber that can inhibit the absorption of water
Optimal design method of the load-level isolation system for industrial steel racking
This paper focuses on an innovative system for mitigating seismic actions on industrial steel racking, called Load-Level Isolation System (LLIS). It consists of placing isolators directly between the pallet masses and the load level, thus exploiting the pallet masses (much greater than the structural mass) as tuned mass dampers. Specifically, the paper aims to derive a general design procedure for the LLIS, based on the amount of mass isolated, the position of the LLIS within the rack, and the main dynamic characteristics of the structural system. To this end, an analytical optimization method is proposed, based on the minimization of the displacement variance of a reduced structural model, representative of the rack dynamics with the LLIS. This method is applied parametrically to derive the optimal damping and frequency values of the LLIS in various design situations, and a sensitivity analysis is subsequently conducted to propose cost-effective LLIS design solutions. Prediction models of the LLIS parameters are therefore provided, as well as a simple step-by-step procedure for designing the control system. Finally, a case study is presented, with the dual objectives of showing the application of the design procedure and the effectiveness of the LLIS in mitigating seismic effects in a standard pallet rack. The results of the Time-History analysis demonstrate the validity of the proposed design method and the possibility of achieving large reductions in the seismic response of the rack using this control system, and up to 60% for both maximum displacements and axial forces of the uprights
Mampuan Komunikasi Matematis Dalam Pemecahan Masalah Matematika Sesuai Dengan Gaya Kognitif Pada Siswa Kelas IX SMP Negeri 1 Surakarta Tahun Pelajaran 2012/2013
The purpose of this research was describing the ability of mathematical communication in solving the mathematics problem. This research was include of study case situation analysis research. The subjects of this research consisted of four students of Class IXb of the ninth grade SMPN 1 Surakarta in the second semester of the academic year 2012/2013. They were two students who had field dependence cognitive style and two students who had field independence cognitive style. The subjects were taken by using the purposive sampling technique. The data of this research were gathered through think aloud method. The data were then analyzed by using the technique with the procedureas follows: (1) the data were classified on the basis of the indicators of mathematical communication after the data had been obtained from the first and the second collections; (2) the data were presented in table form; and (3) the conclusions were drawn. The validity of the data was conducted by using time triangulation. The result of this research were analyzed by using constant comparison in which subject in i (i= 1, 2) with the j (j= 1, 2) cognitive style which was already valid as well compared with subject in k (k= 1, 2) with the the j (j= 1, 2) cognitive style which was already valid as well. The equal ability of mathematical communication was made the main finding wheares the different ability of mathematical communication was made the other finding. The result of this research valid because of the dependability proved. The ability of mathematical communication of the students with the field dependence cognitive style is different from that of those with the field independence cognitive style. The students with the field dependence cognitive style can communicate the ideas in written way well but they have difficulties in communicating ideas in spoken way as well as inclination to receive information without reorganizing it in such a way that the problem-solving ideas presented cannot reveal the actual problem solution. Meanwhile, the students with the field independence cognitive style can communicate the ideas well in both spoken and written ways and process as well as reorganize information in such a way that the problem-solving ideas presented can reveal the actual problem solution
The impact of Action Schools! BC on the health of aboriginal children and youth living in rural and remote communities in British Columbia
Objectives: The aim of the study was to determine the short-term impact of a 7-month whole-school physical activity and healthy eating intervention (Action Schools! BC) over the 2007-2008 school year for children and youth in 3 remote First Nations villages in northwestern British Columbia. Study design: A pre-experimental pre/post design was conducted with 148 children and youth (77 males, 71 females; age 12.5±2.2 yrs). Methods: We evaluated changes in obesity (body mass index [wt/ht 2] and waist circumference z-scores: zBMI and zWC), aerobic fitness (20-m shuttle run), physical activity (PA; physical activity questionnaire and accelerometry), healthy eating (dietary recall) and cardiovascular risk (CV risk). Results: zBMI remained unchanged while zWC increased from 0.46±1.07 to 0.57±1.04 (pB0.05). No change was detected in PA or CV risk but aerobic fitness increased by 22% (25.4±15.8 to 30.9±20.0 laps; p\u3c0.01). There was an increase in the variety of vegetables consumed (1.10±1.18 to 1.45±1.24; p\u3c0.05) but otherwise no dietary changes were detected. Conclusions: While no changes were seen in PA or overall CV risk, zWC increased, zBMI remained stable and aerobic fitness improved during a 7-month intervention. © 2012 Dona Tomlin et al
Australian older adults\u27 views on using social media for reducing social isolation and loneliness in hearing impaired older adults: A community conversation
Objective(s): The objective of this study was to conduct a community conversation to identify the views of the community members when designing an online community using Facebook to support the psychosocial well-being of hearing-impaired older adults. Methods: A community conversation was held with 40 older adults aged more than 60 years. The participants were divided into groups of five and asked to discuss three open-ended questions. The researchers facilitated the discussions. Results: The overwhelming response from this group was that they did not use Facebook or social media as a tool for social connection and did not see the benefits of social media applications. They preferred phone calls or in-person events to maintain their social relationships. Conclusions: Implications for areas of future research and interventions that target loneliness in older adults are discussed
First-order structural transition in the magnetically ordered phase of Fe1.13Te
Specific heat, resistivity, magnetic susceptibility, linear thermal expansion
(LTE), and high-resolution synchrotron X-ray powder diffraction investigations
of single crystals Fe1+yTe (0.06 < y < 0.15) reveal a splitting of a single,
first-order transition for y 0.12. Most
strikingly, all measurements on identical samples Fe1.13Te consistently
indicate that, upon cooling, the magnetic transition at T_N precedes the
first-order structural transition at a lower temperature T_s. The structural
transition in turn coincides with a change in the character of the magnetic
structure. The LTE measurements along the crystallographic c-axis displays a
small distortion close to T_N due to a lattice striction as a consequence of
magnetic ordering, and a much larger change at T_s. The lattice symmetry
changes, however, only below T_s as indicated by powder X-ray diffraction. This
behavior is in stark contrast to the sequence in which the phase transitions
occur in Fe pnictides.Comment: 6 page
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