Estimation and Mitigation of Unknown Airplane Installation Effects on GPA Diagnostics

In gas turbines used for airplane propulsion, the number of sensors are kept at a minimum for accurate control and safe operation. Additionally, when data are communicated between the airplane main computer and the various subsystems, different systems may have different constraints and requirements regarding what data transmit. Early in the design process, these parameters are relatively easy to change, compared to a mature product. If the gas turbine diagnostic system is not considered early in the design process, it may lead to diagnostic functions having to operate with reduced amount of data. In this paper, a scenario where the diagnostic function cannot obtain airplane installation effects is considered. The installation effects in question is air intake pressure loss (pressure recovery), bleed flow and shaft power extraction. A framework is presented where the unknown installation effects are estimated based on available data through surrogate models, which is incorporated into the diagnostic framework. The method has been evaluated for a low-bypass turbofan with two different sensor suites. It has also been evaluated for two different diagnostic schemes, both determined and underdetermined. Results show that, compared to assuming a best-guess constant-bleed and shaft power, the proposed method reduce the RMS in health parameter estimation from 26% up to 80% for the selected health parameters. At the same time, the proposed method show the same degradation pattern as if the installation effects were known.

On the Surface and Beyond. Degradation Morphologies Affecting Plant Ash-Based Archaeological Glass from Kafir Kala (Samarkand, Uzbekistan)

The study focuses on an assemblage of glass finds from the citadel of Kafir Kala, Uzbekistan, located along one of the major Eurasian branches of the “Silk Roads” with a consistent occupation between the 8th and 12th century CE. Glass fragments for this study were selected based on marked surface alterations they showed, with stratified deposits of different thickness and colours. Starting from a preliminary observation under Optical Microscope, fragments were clustered into four main groups based on the surface appearance of the alterations; Scanning Electron Microscopy investigations of the stratigraphy of the alteration products were then carried out, to evaluate micro-textural, morphological and compositional features. Data from the analyses allowed identifying preferential patterns of development of the various degradation morphologies, linkable to compositional alterations of the glass due to burial environment and the alkali leaching action of the water. Iridescence, opaque weathering (at times associated with black stains), and blackening were identified as recurring degradation morphologies; as all but one sample were made of plant ash-based glass, results show no specific correlation between glass composition and the occurrence of one or the other degradation pattern, often found together. Framed in a broad scenario, the paper aims to set the basis for the development of a study approach dedicated to the degradation morphologies affecting archaeological glasses, a topic still lacking systematisation and in-depth dedicated literature.

Performance degradation of metal rubber seal under high temperature and pressure

Seals are crucial components of mechanical devices; seal degradation limits the performance of mechanical systems and even causes accidents. In this work, we used a complex sealing test system to conduct long-term leakage experiments of metal rubber seals as a function of temperature and pressure. The leakage rate was the performance degradation indicator. We developed an experimental performance degradation pattern by linear regression. We combined the leakage pattern of metal rubber seals with leakage theory and found that the increase in the equivalent leakage channel height is the immediate reason for metal rubber seal performance degradation, itself fundamentally attributable to the time-dependent plasticity caused by material creep.

Mapping External Mortar Render (RAF) defects: case study in multi-storey residential buildings

This study aims to identify, map, and quantify the external mortar render (EMR) defects of 22 multi-storey buildings located in the Fernandópolis city, Brazil. Incidence (M-INC) and intensity (M-INT) methods were used to quantify the building defect (BD) of five typified facade regions: continuous wall (1-OCW), around openings (2-OOP), top of parapets and eaves (3-TOP), below balconies, soffits or ledges (4-BCE), and on corners and edges (5-OCE). In addition, three degradation pattern maps were created. We observed 4351 and 481 BDs by M-INT and M-INC, respectively. The most frequent problems were stains and cracks. The most affected regions by M-INT were 2-OOP (34.5%), 1-OCW (23.3%), and 4-BCP (21.6%) while by M-INC were 1-OCW (39.9%), 3- TOP (29.3%), and 2-OOP (16.6%).

Methanogenic Biodegradation of iso-Alkanes by Indigenous Microbes from Two Different Oil Sands Tailings Ponds

iso-Alkanes, a major fraction of the solvents used in bitumen extraction from oil sand ores, are slow to biodegrade in anaerobic tailings ponds. We investigated methanogenic biodegradation of iso-alkane mixtures comprising either three (2-methylbutane, 2-methylpentane, 3-methylpentane) or five (2-methylbutane, 2-methylpentane, 2-methylhexane, 2-methylheptane, 2-methyloctane) iso-alkanes representing paraffinic and naphtha solvents, respectively. Mature fine tailings (MFT) collected from two tailings ponds, having different residual solvents (paraffinic solvent in Canadian Natural Upgrading Limited (CNUL) and naphtha in Canadian Natural Resources Limited (CNRL)), were amended separately with the two mixtures and incubated in microcosms for ~1600 d. The indigenous microbes in CNUL MFT produced methane from the three-iso-alkane mixture after a lag of ~200 d, completely depleting 2-methylpentane while partially depleting 2-methylbutane and 3-methylpentane. CNRL MFT exhibited a similar degradation pattern for the three iso-alkanes after a lag phase of ~700 d, but required 1200 d before beginning to produce methane from the five-iso-alkane mixture, preferentially depleting components in the order of decreasing carbon chain length. Peptococcaceae members were key iso-alkane-degraders in both CNUL and CNRL MFT but were associated with different archaeal partners. Co-dominance of acetoclastic (Methanosaeta) and hydrogenotrophic (Methanolinea and Methanoregula) methanogens was observed in CNUL MFT during biodegradation of three-iso-alkanes whereas CNRL MFT was enriched in Methanoregula during biodegradation of three-iso-alkanes and in Methanosaeta with five-iso-alkanes. This study highlights the different responses of indigenous methanogenic microbial communities in different oil sands tailings ponds to iso-alkanes.

Thermal Regime and Variations in the Island Permafrost Near the Northern Permafrost Boundary in Xidatan, Qinghai–Tibet Plateau

Although the thermal regime and degradation of permafrost on the Qinghai-Tibet Plateau (QTP) have been widely documented, little information exists regarding the island permafrost in the area. Ground temperatures were therefore measured for 8 years (2013–2020) at a permafrost island and at two contrasting sites in the Xidatan region to elucidate the permafrost in this area. Results indicate that the ground temperatures in the island permafrost were markedly higher than those at the same depth in the nearby marginal permafrost and the interior continuous permafrost. In addition, a distinct increasing trend was observed in the ground temperature of the island permafrost over the past 8 years, and warming was signficanty faster in the deep soil than in the topsoil, indicating a bottom–up degradation pattern in the island permafrost. Moreover, due to the persistent increase in the thickness of the active-layer and the decrease in the depth of permafrost table, the permafrost island abruptly disappeared in 2018, which may be attributed to the anomalously high air temperatures that occurred in 2016 and 2017. The results of this study may provide references for understanding of the thermal regime and degradation process of island permafrost on the QTP.

Rumen Degradability of Barley, Oats, Sorghum, Triticale, and Wheat In Situ and the Effect of Pelleting

Feeding cereal grain to cattle is common practice for optimal beef and milk production. High concentrations of starch and other soluble carbohydrates may cause acidosis. Information on the effect of processing on starch and protein degradability in the rumen are scarce. This study was to determine the ruminal degradation patterns of common grains and the effect of steam pelleting on starch and crude protein (CP) degradability in the rumen. The ruminal degradation pattern of dry matter (DM), starch, and CP of ground and pelleted sorghum, barley, wheat, and samples along with ground oats and triticale were determined using the in situ nylon bags method. Cereals were incubated for 0, 2, 4, 6, 8, 16, 32, and 60 h, and the fast and slowly degradable fraction, the effective degradation rate, and effective degradability (ED) of DM, starch, and CP were calculated. The starch ED of ground and pelleted sorghum, barley, and two wheat samples were 57.3, 93.6, 95.2, and 97.2%; and 61.5, 93.8, 93.8, and 95.6%, and their crude protein ED was 54.8, 82.3, 83.3, 82.6% and 51.9, 79.2, 81.8, and 78.1% respectively. The starch ED of ground oat and triticale were 98.3 and 94.7%, and that of CP were 93.7 and 75.2%, respectively. The degradability of sorghum was significantly lower than that of the other grains. Pelleting increased the fast-degradable DM and starch faction of sorghum and tended to improve its DM degradability (p = 0.081). Pelleting significantly reduced the fast-degradable fraction of DM and starch of wheat samples and numerically reduced its degradability.