Methods for Determining Grease Service Levels in an AH-64D Intermediate Gearbox Using On-Board Sensors

The intermediate gearbox (IGB) on the AH-64D was chosen as the subject for this study based on the persistent grease leaks that require grounding aircraft. The aircraft is not currently equipped with a method of detecting grease loss during flight, so techniques for analyzing the usefulness of old metrics and possible new techniques can be tested. The main objective of this study is to use the aircraft’s on-board sensors to develop a method of determining the lubrication level of the IGB. Currently, the most reliable method for detecting a fault on the aircraft is through the use of vibration-based condition indicators (CIs). The results of this research show a negative correlation between vibration and grease service levels when analyzing specific CIs for the IGB on the AH-64, which can be basis for automated leak detection. Another objective of this study is to quantify the standard operational grease level for IGBs in the AH-64 fleet. This standard would be created by measuring the amount of grease left in each gearbox after burping. This grease level would then be used to insure that if lubricant was leaking out of the component, it is due to a fault instead of an overfilled article. If the level is the same for each gearbox then a new standard can be implemented to prevent burping. By being able to use an installed on-board sensor to indicate the level of grease in the gearbox this would relieve the burden of the maintainer from having to check the level every 25 flight hours. The soldier would then be able to spend his time in another area that is more critical than a routine maintenance item. For this analysis three gearboxes of similar condition were used. Each one was run for two hours at five different grease service levels of 0%, 25%, 50%, 75%, and 100%, based on the Army Depot standard amount of 964 grams. These gearboxes were tested on the USC tail rotor drivetrain (TRDT) test stand according to a test plan defining operational conditions. The test plan specifies torque and speed values that are similar to those experienced by the component during flight. The existing on-board modernized signal processing unit (MSPU) CIs, the raw time-domain data, and temperature data were collected and analyzed to try and identify a CI to indicate grease level. By using statistical analysis tools and some know fault cases. CIs can give the user a different view into the operation of the gearbox as opposed to standard vibration analysis. This happens to hold true for this experiment, in which investigation of the two CIs, output bearing energy and input bearing energy, revealed an inverse correlation between grease level and vibration magnitude. Out of the two algorithms mentioned, the input bearing energy had the strongest correlation, making it the best candidate for monitoring grease level through vibration in the field. The raw vibration data collected, unlike the conditioned MSPU, data was too noisy and did not yield any valuable results. It was also noted that gearbox temperature increased as the grease service level increased; this was unexpected because it was believed that the greater the service level of the component, the lower the operating temperature would be. This trend was more stable and consistent from gearbox to gearbox than the one seen using the vibration data. These results prove that it is possible to monitor the quantity of grease in the gearbox through on-board sensors, and also serve as a testament to the usefulness of putting condition-based maintenance techniques into practice in the field

Effect of dietary beta-agonist supplementation on live performance, carcass characteristics, carcass fabrication yields, and strip loin tenderness and sensory traits

2012 Fall.Includes bibliographical references.Beef steers (n = 3,906) were fed at a commercial feed yard to evaluate the effects of beta-adrenergic agonist supplementation on live performance, carcass characteristics, carcass fabrication yield and strip loin tenderness and palatability. Steers were weighed and ultrasonic carcass measurements were collected for allocation into four feeding blocks. Within each block, approximately 100 steers were assigned two a pen that was assigned one of five treatments, including: No beta-agonist; Ractopamine hydrochloride (RH) fed at 200 mg/hd/d for the final 30 d of finishing (RAC200); RH fed at 300 mg/hd/d for the final 30 d of finishing (RAC300); RH fed as a 400 mg/hd/d top dress for the final 30 d of finishing (RAC400); and Zilpaterol hydrochloride (ZH) fed at 6.8 g/ton beginning 23 d before slaughter, with a withdrawal period starting 3 d before to slaughter (ZIL). The study design included eight replicates (pens) per treatment (two per block). Each feeding block was harvested on consecutive weeks. Each week, carcass parameters were measured and strip loin samples were collected from 18 carcasses per pen (720 total samples) for Warner-Bratzler and Slice Shear Force, and trained sensory analysis. Subsamples of eight carcasses per pen (320 total samples) were selected for whole carcass fabrication yield. Final BW was not affected by treatment (P = 0.2892), but there was a tendency for cattle receiving βAA supplementation to be heavier compared to controls (P = 0.0681). Average daily gain and F:G ratio was improved with treatment of βAA (P < 0.05). Carcasses from the ZIL and RAC400 treatments had the heaviest HCW, and were significantly heavier than CON and RAC200 treatments (P < 0.05). The ZIL treatment also recorded the highest dressing percent and carcasses had the largest LMA compared to all other treatments (P < 0.05). USDA yield grade and marbling score were reduced due to βAA supplementation (P < 0.05). Differences in marbling score reduced the frequency of carcass qualifying for the CAB premium in βAA treated cattle (P < 0.05), while also accounting for a decrease in the frequency of carcasses grading choice and an increase in the percentage of carcasses grading select for cattle receiving βAA supplementation compared to controls (P < 0.05). The percentage of YG1 carcasses was increased and the frequency of YG3 carcasses was decreased due to βAA treatment (P < 0.05). Treatment with dietary βAA elicited the greatest response in subprimal yield in cuts from the round. Zilpaterol treatment carcasses reported the highest total saleable yield, and were greater than all RAC treatments (P < 0.05). Warner-Bratzler and SSF was affected by treatment (P < 0.05), with an increase in shear force values with increased dose and potency of βAA's. Likewise, the percentage of steaks shearing greater than 4.4 and 20 kg for WBSF and SSF, respectively, was increased with βAA supplementation (P < 0.05). Tenderness attributes were ranked lower for steaks from βAA treatments by trained sensory panelists (P < 0.05). There were no differences detected by panelists for juiciness or beef flavor attributes

Social assemblages and mating relationships in prairie dogs: a DNA fingerprint analysis

Mating system characterizations have been hindered by difficulties in accurately assigning parentage to offspring. We investigated the relationship between social assemblages and mating relationships in a territorial harem polygynous mammal, the Gunnison\u27s prairie dog, using a combination of behavioral and molecular analyses. We demonstrate multiple paternity and an extraordinarily high incidence of extraterritorial fertilizations (i.e., 61% of all progeny), in combination with the existence of female kin groups. On this basis, we conclude that social assemblages alone provide a poor description of the Gunnison\u27s prairie dog mating system, and suggest several potential reasons for the maintenance of territoriality in this species

Coherent Excitonic Coupling in an Asymmetric Double InGaAs Quantum Well Arises from Many-Body Effects

We study an asymmetric double InGaAs quantum well using optical two-dimensional coherent spectroscopy. The collection of zero-quantum, one-quantum, and two-quantum two-dimensional spectra provides a unique and comprehensive picture of the double well coherent optical response. Coherent and incoherent contributions to the coupling between the two quantum well excitons are clearly separated. An excellent agreement with density matrix calculations reveals that coherent interwell coupling originates from many-body interactions

Homelessness across Alaska, the Canadian North and Greenland: A Review of the Literature on a Developing Social Phenomenon in the Circumpolar North

Over the past three decades, homelessness has become an area of significant social concern in Alaska, the Canadian North, and most recently, Greenland. These three geographical contexts show both similarities and contrasts, but no effort has yet been made to review the research literature on homelessness from these three regions or to highlight key themes or gaps in current knowledge. We reviewed the literature in order to 1) understand the current state of knowledge of the dynamics of homelessness in Alaska, the Canadian North (here including Yukon, Northwest Territories, and Nunavut), and Greenland and 2) conceptualize a northern geography of homelessness. The research literature identifies common themes across these contexts, which include chronic housing insecurity, overrepresentation of Indigenous peoples among those living homeless, and the significance of gendered experiences of homelessness. It identifies key interconnections between hidden homelessness and visible homelessness as the dynamics of urbanization in northern towns and cities reveal the social consequences of chronic housing insecurity in settlements. Across these northern regions, the high rates of chronic homelessness reflect the prevalence of northern housing insecurity and the lack of both adequate, appropriate support for people experiencing mental health or addiction problems and supportive or public housing options. Strategies that aim to diversify housing stock at various critical points along the housing spectrum are needed in northern regions, an idea that is promoted by Housing First and transitional housing programs in Alaska and the Canadian North.Au cours des trois dernières décennies, le sans-abrisme est devenu une grande préoccupation sociale en Alaska, dans le Nord canadien et, plus récemment, au Groenland. Ces trois contextes géographiques présentent des similitudes et des différences, mais aucun effort n’a encore été déployé pour examiner la documentation de recherche sur le sans-abrisme dans ces trois régions ou pour mettre en évidence les principaux thèmes ou les principales lacunes en ce qui a trait aux connaissances actuelles. Nous avons dépouillé la documentation dans le but de 1) comprendre l’état actuel des connaissances sur les dynamiques du sans-abrisme en Alaska, dans le Nord Canadien (dans ce cas-ci le Yukon, les Territoires du Nord-Ouest et le Nunavut) et au Groenland, et 2) de conceptualiser une géographie nordique du sans-abrisme. La documentation de recherche fait ressortir des thèmes communs parmi ces contextes, notamment l’insécurité chronique en matière de logement, la surreprésentation des peuples autochtones parmi les itinérants et la signification de l’expérience du sans-abrisme selon le sexe. La documentation cerne les principaux liens entre le sans-abrisme caché et le sans-abrisme visible alors que les dynamiques de l’urbanisation dans les villages et les villes du Nord exposent les conséquences sociales de l’insécurité chronique en matière de logement dans les agglomérations. Dans l’ensemble de ces régions nordiques, les taux élevés de sans-abrisme chronique reflètent la prévalence de l’insécurité en matière de logement dans le Nord, le manque de soutien adéquat et approprié pour les gens aux prises avec des troubles de santé mentale ou de toxicomanie et le manque d’options de logements sociaux ou supervisés. Des stratégies visant à diversifier le parc de logements à divers points critiques de la gamme des logements s’avèrent essentielles dans les régions du Nord. D’ailleurs, l’approche Logement d’abord et les programmes de logement de transition font la promotion de cette idée en Alaska et dans le Nord canadien

DNA Fingerprinting Reveals Low Genetic Diversity in Gunnison\u27s Prairie Dog (Cynomys gunnisoni)

The use of molecular techniques for the assessment of familial relationships among social species of mammals has become relatively commonplace. However, some species represent poor candidates for such studies due to naturally low levels of genetic diversity, leading to unacceptably large standard errors associated with estimates of relatedness. Here, we report on a preliminary study of genetic diversity within two populations of a social species of ground squirrel, Gunnison\u27s prairie dog (Cynomys gunnisoni) using DNA fingerprinting. We observed low levels of diversity in the form of large mean coefficients of genetic similarity among individuals occupying the same population. Overall similarity, determined from the combined data, yielded by three minisatellte probes, ranged from 55 to 61%. These values place Gunnison\u27s prairie dog at the extreme upper end of the range of similarity values reported for outbred species of mammals (ca. 0.20-0.50). As a partial means of explaining these results, and as a means of comparing our results to those of similar studies using allozymes, we determined the level of differentiation between our two study colonies in the form of an F-statistic analog. A value of 0.11 (± 2.26 × 10−3) was obtained and is similar to values reported from allozyme studies (0.07–0.12). A significance test of this value yielded a positive result (D = 5.63, d.f. = 1, P \u3c 0.025), demonstrating that gene flow between populations is limited, a factor that may help to maintain low levels of diversity

DNA Fingerprinting Reveals Low Genetic Diversity in Gunnison\u27s Prairie Dog (Cynomys gunnisoni)

The use of molecular techniques for the assessment of familial relationships among social species of mammals has become relatively commonplace. However, some species represent poor candidates for such studies due to naturally low levels of genetic diversity, leading to unacceptably large standard errors associated with estimates of relatedness. Here, we report on a preliminary study of genetic diversity within two populations of a social species of ground squirrel, Gunnison\u27s prairie dog (Cynomys gunnisoni) using DNA fingerprinting. We observed low levels of diversity in the form of large mean coefficients of genetic similarity among individuals occupying the same population. Overall similarity, determined from the combined data, yielded by three minisatellte probes, ranged from 55 to 61%. These values place Gunnison\u27s prairie dog at the extreme upper end of the range of similarity values reported for outbred species of mammals (ca. 0.20-0.50). As a partial means of explaining these results, and as a means of comparing our results to those of similar studies using allozymes, we determined the level of differentiation between our two study colonies in the form of an F-statistic analog. A value of 0.11 (± 2.26 × 10−3) was obtained and is similar to values reported from allozyme studies (0.07–0.12). A significance test of this value yielded a positive result (D = 5.63, d.f. = 1, P \u3c 0.025), demonstrating that gene flow between populations is limited, a factor that may help to maintain low levels of diversity