1,807 research outputs found

    The optical field angle distortion calibration feasibility study for the Hubble Space Telescope fine guidance sensors

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    The results of an analytical study to investigate the feasibility of calibrating the Hubble Space Telescope's (HST's) fine guidance sensors (FGSs) within HST mission accuracy limits are presented. The study has two purposes: (1) to determine the mathematical feasibility of the optical field angle distortion (OFAD) calibration algorithm and (2) to confirm that the OFAD, plate scale, and FGS-to-FGS alignment calibration algorithms produced a calibration of the FGSs that satisfied mission requirements. The study concluded that the mathematical specification of the OFAD algorithm is adequate and permits a determination of the FGS calibration parameters (accurate to better than 0.003 arc-second) sufficient to meet the mission requirements. The algorithms implemented, the characteristics of the simulated data and procedures for data analysis, and the study's results are discussed. In addition, several useful techniques for improving the stability and accuracy of the OFAD solution are outlined

    Desalinating seawater and recovering waste water using hybrid forward and reverse osmosis at the pilot level

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    With the advantage of having low fouling propensity and requiring low hydraulic pressure to operate, forward osmosis (FO) has captured attention as an alternative technology which is capable of treating and desalinating highly fouling and saline water sources respectably. Established technologies such as reverse osmosis (RO) is capable of performing the aforementioned tasks at high efficiency. However, RO often requires extensive pretreatment to reduce membrane fouling which increases cost. In this work, a pilot scale FO-RO system was built using commercially available membrane modules. A combined hybrid FO-RO system where FO acts as a pre-treatment system to downstream RO system and RO acts as a recovery step for FO draw solution offers a multitude of benefits. Reduction in fouling, and fast and low cost cleanability is achievable. In addition, having similar membrane selectivity, both FO and RO provides a dual barrier protection to trace contaminants such as boron, low molecular weight organics, and metals. The pilot system includes a PLC-HMI based data acquisition system with process control and monitoring capability of flowrates, pressures, temperatures, and electricity usage. Initially, using DI water as a benchmark for evaluating the fundamental operating parameters that are critical to FORO, the system was optimized. Using a Dow SW30-4040 spiral wound module and Porifera FOMEM plate and frame module, the system was operated at 40%-45% recovery. During this recovery, the feed concentration in the RO changed from 4000 TDS to 12000 TDS with a rejection of 93%-97% at a pH of 6.5. For a 0.25M NaCl draw solution in FO, a 10-12 Lm-2hr-1 water flux was observed with a reverse salt flux of 11-13 gm-2hr-1. The total peak current used was found to be 4.0-4.5 amps at a maximum feed and draw flowrate of 1.25 GPM. We anticipate an automated process control through mass transport between the FO and RO module in closed loop. Our future work include investigation of different types of feed sources to observe and record the operating parameters as well as to investigate the double barrier concept and the automated process control feature of the FO-RO hybrid system. Please click Additional Files below to see the full abstract

    Trimethylamine draw solute in osmotic heat engine for power generation

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    Naturally occurring salinity gradients, such as where river water meets seawater, were considered untapped sources energy that could be harnessed with technologies like pressure retarded osmosis (PRO). Unfortunately, relatively low osmotic pressure of seawater limits power generation potential. Pretreatment to remove contaminants in natural streams would be cost prohibitive and could result a substantial loss in energy production [1]. The concept of the osmotic heat engine (OHE), addresses these two problems of PRO. The OHE is a “closed loop” PRO process with a thermally regenerable draw solute. By choosing a thermolytic solute with a high solubility, osmotic pressures far in excess of seawater are possible. In addition, no pretreatment is needed because the solutions are pristine and contain no foulants. OHEs therefore can produce far more power and with fewer losses than conventional PRO. The development of the OHE was made possible by the recently developed NH3-CO2 thermolytic draw solute. This solute, which in water consists of ammonium salts, can be easily regenerated by conventional steam stripping and was the focus of numerous studies on forward osmosis (FO) [2, 3]. However, one of the major challenges with the NH3-CO2 solute is its high reverse salt flux, impairing the water flux and power density due to lost osmotic pressure and internal concentration polarization. A newly investigated thermolytic draw solute is trimethylamine–carbon dioxide (TMA–CO2). Like NH3-CO2, TMA–CO2 has a high solubility in water and can generate high osmotic pressure. It also features comparable volatility to ammonia and low enthalpy of vaporization, indicating comparable or less energy would be consumed for draw solute regeneration. The benefit of TMA–CO2 lies in its larger molecular size. This makes it less likely to pass through the membrane. In this work, we explore the use of TMA–CO2 in PRO and compare its performance to other model draw solutes (NaCl) and NH3-CO2. Tests were conducted with up to 5 M solutions of TMA–CO2 using a lab-scale PRO test system with a proprietary Porifera membrane. Estimated power densities of up to 18.6 W m-2 were achievable at relatively low pressures (10 bar). For comparison, NaCl and ammonia-carbon dioxide (NH3–CO2) have been evaluated for PRO performance using Porifera membrane. The water flux of TMA-CO2 was about 20 % lower than that of NaCl and comparable with that of NH3–CO2. Reverse solute flux of TMA–CO2 ranged from 0.5 to 3.5 mol m−2 h−1 in all experiments. This value was much lower than NH3-CO2 (4.0 to 51 mol m−2 h−1 ) and approximately half that of NaCl. Low solute flux was attributed to molecular size differences between solutes. In addition, the overall PRO performance of TMA-CO2 (higher water flux, lower salt flux and higher power density) can be further improved by conditioning the existing membrane prior to PRO testing. It has been proved by our result that by conditioning porifera membrane under 150 psi pressure (essentially in RO) for 2 hours prior to testing under relevant PRO conditions with 3 M NaCl, water flux increases by 17% and salt flux drops by an astonishing 85%. In all, TMA-CO2 represents an OHE draw solute option with low draw solute flux without substantial sacrifice of power density. This solute, as well as its many derivatives, may therefore represent the “sweet spot” for thermolytic OHE systems. [1] N.Y. Yip, M. Elimelech. Environ.Sci.Technol., 46 (2012) 5230. [2] J.R. McCutcheon, R.L. McGinnis, and M. Elimelech. J.Membr.Sci., 278 (2006) 114. [3] R.L. McGinnis, N.T. Hancock, M.S. Nowosielski-Slepowron, and G.D. McGurgan. Desalination, 312 (2013) 67

    Optimizing hollow fiber membranes and modules for osmotic processes: Membranes, modules, and models

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    Hollow fiber membranes have long been considered a valuable platform for membrane separations because of their high packing density relative to flat sheet membranes. Recently, the osmotic process community has developed hollow fiber membranes intended for forward osmosis (FO) and pressure retarded osmosis (PRO) applications in order to capitalize on these same advantages. Many of these hollow fiber membranes were made using a thin film composite (TFC) approach with the focus on the design of support layer toward a thin, highly porous, minimally tortuous supporting structure to minimize the mass transfer resistance during osmotic processes. These hollow fiber FO membranes demonstrated excellent FO performance, but also suggested a need for intensively and delicately tailored membrane support layers which can lead to compromised membrane properties. This study evaluates an approach to make thin film composite hollow fiber membranes for forward osmosis by simply employing commercial hollow fiber ultrafiltration (UF) membranes as support material. A thin polyamide film with excellent selective properties was synthesized on the inner surface of hollow fibers via interfacial polymerization. Besides demonstrating the feasibility to be used as good TFC FO membrane supports, the commercial hollow fiber UF membranes also provide a systematic platform with consistent properties to study structure-performance relationship of FO hollow fiber membranes. A series of commercial hollow fiber membranes were used to evaluate how molecular weight cutoff (MWCO) impacted the properties of the polyamide layer and overall performance of the TFC membrane. Aside from using commercial hollow fiber UF membranes as FO membrane supports at bench scale, we also demonstrate that the TFC hollow fiber FO membranes can be made on existing hollow fiber modules at pilot scale. A series of commercial hollow fiber modules with different fiber size were used to make TFC hollow fiber FO membrane modules. The resultant TFC hollow fiber membranes were evaluated under various operating conditions (membrane orientation, cross flow arrangement, cross flow velocity, and draw solution concentration). While we evaluate how basic performance metrics (water and solute flux) are impacted by module operating conditions, overall the modules demonstrate impressive FO performances. The facile approach for modification may promote exploration of other hollow platforms for even better performance. With the availability of reproducible membranes and modules, we have developed a computational fluid dynamics (CFD) model with COMSOL Multiphysics to study the impacts of hollow fiber and module properties in order to optimize hollow fiber module design for FO application. Properties like module dimensions (length, width) as well as fiber dimensions (inner diameter and outer diameter) were modeled to better elucidate how such features impact performance. The FO process in a hollow fiber membrane was simulated in a 2D axis-symmetry geometry and described by fluid dynamics coupled with mass transfer across the membrane. We verified the models accuracy by constructing modules with the same dimensions and fibers and testing under pertinent conditions. The agreement between the model and experimental results provided insight into both how more accurate models can be developed and how these models can be used to design better modules without costly experimental testing

    Great Mining Camps of Canada 8. The Bathurst Mining Camp, New Brunswick, Part 2: Mining History and Contributions to Society

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    In the Bathurst Mining Camp (BMC), 12 of the 45 known massive sulphide deposits were mined between 1957 and 2013; one was mined for iron prior to 1950, whereas three others had development work but no production. Eleven of the deposits were mined for base metals for a total production of approximately 179 Mt, with an average grade of 3.12% Pb, 7.91% Zn, 0.47% Cu, and 93.9 g/t Ag. The other deposit was solely mined for gold, present in gossan above massive sulphide, producing approximately one million tonnes grading 1.79 g/t Au. Three of the 11 mined base-metal deposits also had a gossan cap, from which gold was extracted. In 2012, the value of production from the Bathurst Mining Camp exceeded 670millionandaccountedfor58percentoftotalmineralproductioninNewBrunswick.Base−metalproductionstartedintheBMCin1957fromdepositsatHeathSteeleMines,followedbyWedgein1962,BrunswickNo.12in1964,BrunswickNo.6in1965,Caribouin1970,MurrayBrook,StratmatBoundaryandStratmatN−5in1989,CaptainNorthExtensionin1990,andlastly,HalfMileLakein2012.TheonlymineincontinuousproductionformostofthistimewasBrunswickNo.12.Duringits49−yearlifetime(1964–2013),itproduced136,643,367tonnesoforegrading3.44670 million and accounted for 58 percent of total mineral production in New Brunswick.Base-metal production started in the BMC in 1957 from deposits at Heath Steele Mines, followed by Wedge in 1962, Brunswick No. 12 in 1964, Brunswick No. 6 in 1965, Caribou in 1970, Murray Brook, Stratmat Boundary and Stratmat N-5 in 1989, Captain North Extension in 1990, and lastly, Half Mile Lake in 2012. The only mine in continuous production for most of this time was Brunswick No. 12. During its 49-year lifetime (1964–2013), it produced 136,643,367 tonnes of ore grading 3.44% Pb, 8.74% Zn, 0.37% Cu, and 102.2 g/t Ag, making it one of the largest underground base-metal mines in the world.The BMC remains important to New Brunswick and Canada because of its contributions to economic development, environmental measures, infrastructure, mining innovations, and society in general. The economic value of metals recovered from Brunswick No. 12 alone, in today’s prices exceeds 46 billion. Adding to this figure is production from the other mines in the BMC, along with money injected into the local economy from annual exploration expenditures (100s of 1000speryear)over60years.SeveralenvironmentalmeasureswereinitiatedintheBMC,includingtherequirementtobecleanshavenandcarryaportablerespirator(nowappliedtoallminesinCanada);waystotreatacidminedrainageandthethiosaltproblemthatcomesfromthemillingprocess;andpioneeringstudiestodevelopandinstallstreamside−incubationboxesforAtlanticSalmoneggsintheNepisiguitRiver,whichboostedsurvivalratestoover901000s per year) over 60 years. Several environmental measures were initiated in the BMC, including the requirement to be clean shaven and carry a portable respirator (now applied to all mines in Canada); ways to treat acid mine drainage and the thiosalt problem that comes from the milling process; and pioneering studies to develop and install streamside-incubation boxes for Atlantic Salmon eggs in the Nepisiguit River, which boosted survival rates to over 90%. Regarding infrastructure, provincial highways 180 and 430 would not exist if not for the discovery of the BMC; nor would the lead smelter and deep-water port at Belledune. Mining innovations are too numerous to list in this summary, so the reader is referred to the main text. Regarding social effects, the new opportunities, new wealth, and training provided by the mineral industry dramatically changed the living standards and social fabric of northern New Brunswick. What had been a largely poor, rural society, mostly dependent upon the fishing and forestry industries, became a thriving modern community. Also, untold numbers of engineers, geologists, miners, and prospectors `cut their teeth’ in the BMC, and many of them have gone on to make their mark in other parts of Canada and the world.Dans le camp minier de Bathurst (CMB), 12 des 45 gisements de sulfures massifs connus ont Ă©tĂ© exploitĂ©s entre 1957 et 2013; un de ces gisements a Ă©tĂ© exploitĂ© pour le fer avant 1950, tandis que trois autres Ă©taient en dĂ©veloppement mais pas en production. Onze gisements ont Ă©tĂ© exploitĂ©s pour des mĂ©taux communs pour une production totale d'environ 179 Mt, avec une teneur moyenne de 3,12% Pb, 7,91% Zn, 0,47% Cu et 93,9 g/t Ag. L'autre gisement Ă©tait uniquement exploitĂ© pour l'or, prĂ©sent dans le gossan au-dessus du sulfure massif, produisant environ un million de tonnes titrant 1,79 g/t Au. Trois des 11 gisements de mĂ©taux communs exploitĂ©s avaient Ă©galement un gossan, d'oĂč l'or Ă©tait extrait. En 2012, la valeur de la production du camp minier de Bathurst dĂ©passait 670 millions de dollars et reprĂ©sentait 58% de la production minĂ©rale totale au Nouveau-Brunswick.La production de mĂ©taux communs a commencĂ© dans le CMB en 1957 Ă  partir des gisements de Heath Steele Mines, suivie de Wedge en 1962, Brunswick no 12 en 1964, Brunswick no 6 en 1965, Caribou en 1970, Murray Brook, Stratmat Boundary et Stratmat N- 5 en 1989, Captain North Extension en 1990, et enfin Half Mile Lake en 2012. La seule mine en production continue pendant la majeure partie de cette pĂ©riode Ă©tait Brunswick no 12. Au cours de sa durĂ©e de vie de 49 ans (1964–2013), elle a produit 136 643 367 tonnes de minerai titrant 3,44% Pb, 8,74% Zn, 0,37% Cu et 102,2 g/t Ag, ce qui en fait l'une des plus grandes mines souterraines de mĂ©taux communs au monde.Le CMB demeure important pour le Nouveau-Brunswick et le Canada en raison de sa contribution au dĂ©veloppement Ă©conomique, aux mesures environnementales, Ă  l'infrastructure, aux innovations miniĂšres et Ă  la sociĂ©tĂ© en gĂ©nĂ©ral. La valeur Ă©conomique des mĂ©taux rĂ©cupĂ©rĂ©s du seul gisement Brunswick n° 12, aux prix d’aujourd’hui, dĂ©passe 46 milliards de dollars. S'ajoute Ă  ce chiffre la production des autres mines du CMB, ainsi que l'argent injectĂ© dans l'Ă©conomie locale par les dĂ©penses d'exploration annuelles (des centaines Ă  des milliers de par an) sur 60 ans. Plusieurs mesures environnementales ont Ă©tĂ© lancĂ©es dans le CMB, y compris l'exigence d'ĂȘtre rasĂ© de prĂšs et de porter un respirateur portatif (maintenant appliquĂ© Ă  toutes les mines au Canada); les moyens de traitement des effluents miniers acides et le problĂšme des thiosels qui proviennent du processus de broyage; et les Ă©tudes pionniĂšres pour dĂ©velopper et installer des boĂźtes d'incubation en bord de riviĂšre pour les Ɠufs de saumon de l'Atlantique dans la riviĂšre Nepisiguit, ce qui a fait passer les taux de survie Ă  plus de 90%. En ce qui concerne les infrastructures, les routes provinciales 180 et 430 n'existeraient pas sans la dĂ©couverte du CMB; la fonderie de plomb et le port en eau profonde de Belledune non plus. Les innovations miniĂšres sont trop nombreuses pour ĂȘtre Ă©numĂ©rĂ©es dans ce rĂ©sumĂ©, le lecteur est donc renvoyĂ© au texte principal. En ce qui concerne les effets sociaux, les nouvelles possibilitĂ©s, la nouvelle richesse et la formation offertes par l'industrie miniĂšre ont radicalement changĂ© le niveau de vie et le tissu social du nord du Nouveau-Brunswick. Ce qui avait Ă©tĂ© une sociĂ©tĂ© rurale en grande partie pauvre, principalement tributaire des industries de la pĂȘche et de la sylviculture, est devenu une communautĂ© moderne florissante. De plus, un nombre incalculable d’ingĂ©nieurs, de gĂ©ologues, de mineurs et de prospecteurs «se sont fait les dents» au CMB, et bon nombre d’entre eux ont continuĂ© Ă  faire leurs marques dans d’autres rĂ©gions du Canada et du monde

    A new Lower Silurian fossil locality in the northeastern Mascarene-Nerepis Belt, southern New Brunswick

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    A new fossil locality from the northeastern part of the Mascarene-Nerepis Belt, previously mapped as "Ordovician or Silurian", gives a precise Liandoverian C5 age. It occurs In a sedimentary sequence that underlies, and in part is laterally equivalent to, volcanic rocks of the Long Reach Formation. It establishes an approximate upper age limit to the Queen Brook Formation and is about the same age as the oldest fossiliferous rocks (Back Bay and Quoddy Formations) in the southwestern Mascarene-Nerepis Belt. RÉSUMÉ Un nouveau site fossilifère, daté avec précision com me Liandovérien C5, a été découvert dans la partie nord-est de la zone Mascarene-Nerepis autrefois cartographiée comme "Ordovicien ou Silurien". Le site fait partie d'une séquence de roches sédimentares qui sont récouvertes par des roches volcaniques appartenant à la Formation de Long Reach, et auxquelles elles sont également en partie équivalentes. Cette découverte précise la limite supérieure de L’âge de la Formation de Queen Brook et correspond à peu près à L’âge des plus anciennes roches fossilifères (Formations de Back Bay et de Quoddy) de la partie sud-ouest de la zone Mascarene-Nerepis. [Traduit par le journal

    Metabolic and cardiovascular adaptation, monkey. NASA SMD 3, project 76, experiment 44 conducted at NASA/JSC, 14-25 May 1977

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    The biomedical results from an experiment on a monkey subjected to space flight conditions are reported. A background history of the development and testing of an experiment system designed to permit measurement of physiological parameters in subhuman primates during continuous, comfortable, couch restraint for periods of up to 30 days is reviewed. Of major importance in the experimental design of the system was the use of a fiberglass pod, which could be sealed and subdivided into upper and lower parts, to monitor and control the physiological responses for various parts of the animal's body. The experiment was conducted within the Spacelab Simulator for a period of 11 days. Data recorded includes: Spacelab Simulator cabin temperature; ventilation rate; pod internal temperature; fraction percent oxygen; fraction percent carbon dioxide; oxygen consumption rate; carbon dioxide production rate; respiratory quotient; intrathoracic temperature; heart rate; mean aortic pressure; mean ventricular pressure; diurnal variation of parameters measured; comparison of mean preflight, flight, and postflight values of the parameters measured; and correlation matrix for the parameters measured