Determining optimum parameters for manual compaction of loose biomass

Abstract: Significant amounts of loose biomass are produced annually through agricultural and forestry activities. It is common practice to burn these loose biomass deliberately after harvesting or in accidental veld fires in the case of forestry. This energy could be harnessed for cooking and heating. The challenge with the use of loose biomass lies in its low density and hence low energy content which can be improved through densification. The aim of this paper is to determine the optimum densification parameters that can be used to develop manual briquetting technologies to empower poor communities to harness the energy available in loose biomass that they dispose annually. This forms part of a larger project aimed at developing off grid biomass value chain technologies. Using loose grass and loose leaves, experimental data revealed an optimum density of 1250 kg/m3 and a corresponding densification pressure of 40 MPa. In addition, a comparison of the thermal profile of solid round and round hollow briquettes showed more superior performance of the round hollow briquette based on recorded maximum combustion temperatures. Briquettes with a hole in the middle are therefore preferred to solid briquettes

Design of chilled ceiling displacement ventilation for direct expansion HVAC system

Abstract: Displacement ventilation is a low cost ventilation technique used in distributing conditioned air in Heating, Ventilation and Air Conditioning (HVAC) systems. This is a ventilation strategy well suited to significantly reduce building energy consumption in this age of high energy costs, global warming and climate change. This is achieved through the leveraging of natural buoyancy driven flow in the conditioned space in a way that minimizes energy expenditure in supply and extraction fans. In addition, the conditioned air is supplied at higher temperature implying lower energy demand for cooling units. The global legislative move towards greener buildings demands the use of sustainable and energy efficient air conditioning systems of which displacement ventilation makes a major contribution. One of the challenges in using displacement ventilation is the stratified temperature distribution in the conditioned space. The temperature gradients between the ceiling and the floor can lead to decreased comfort conditions. One approach to overcome this problem is to use the chilled ceiling. How does one size the chilled ceiling system in such cases? The purpose of this paper is to present a detailed design analysis of a displacement ventilation chamber that includes chilled ceiling. The chamber utilizes an under floor air supply system into a conditioned space configured to represent typical office space. The construction and performance testing of the displacement ventilation testing chamber is then reported in a subsequent paper

Reappraisal of large artery involvement in giant cell arteritis: a population-based cohort over 70 years.

OBJECTIVE: To evaluate the incidence and outcomes of large artery (LA) involvement among patients with giant cell arteritis (GCA) and to compare LA involvement to non-GCA patients. METHODS: The study included Olmsted County, Minnesota, USA residents with incident GCA between 1950 and 2016 with follow-up through 31 December 2020, death or migration. A population-based age-matched/sex-matched comparator cohort without GCA was assembled. LA involvement included aortic aneurysm, dissection, stenosis in the aorta or its main branches diagnosed within 1 year prior to GCA or anytime afterwards. Cumulative incidence of LA involvement was estimated; Cox models were used. RESULTS: The GCA cohort included 289 patients (77% females, 81% temporal artery biopsy positive), 106 with LA involvement.Reported cumulative incidences of LA involvement in GCA at 15 years were 14.8%, 30.2% and 49.2% for 1950-1974, 1975-1999 and 2000-2016, respectively (HR 3.48, 95% CI 1.67 to 7.27 for 2000-2016 vs 1950-1974).GCA patients had higher risk for LA involvement compared with non-GCA (HR 3.22, 95% CI 1.83 to 5.68 adjusted for age, sex, comorbidities). Thoracic aortic aneurysms were increased in GCA versus non GCA (HR 13.46, 95% CI 1.78 to 101.98) but not abdominal (HR 1.08, 95% CI 0.33 to 3.55).All-cause mortality in GCA patients improved over time (HR 0.62, 95% CI 0.41 to 0.93 in 2000-2016 vs 1950-1974) but remained significantly elevated in those with LA involvement (HR 1.89, 95% CI 1.39 to 2.56). CONCLUSIONS: LA involvement in GCA has increased over time. Patients with GCA have higher incidences of LA involvement compared with non-GCA including thoracic but not abdominal aneurysms. Mortality is increased in patients with GCA and LA involvement highlighting the need for continued surveillance

Review of experimental methods to determine spontaneous combustion susceptibility of coal – Indian context

This paper presents a critical review of the different techniques developed to investigate the susceptibility of coal to spontaneous combustion and fire. These methods may be sub-classified into the two following areas: (1) Basic coal characterisation studies (chemical constituents) and their influence on spontaneous combustion susceptibility. (2) Test methods to assess the susceptibility of a coal sample to spontaneous combustion. This is followed by a critical literature review that summarises previous research with special emphasis given to Indian coals

Exchange of nutrients and oxygen across the sediment-water interface below a Sparus aurata marine fish farm in the north-western Mediterranean Sea

Purpose: This study analyzes the effects of aquaculture activities in open seawater in the north-western coastal waters of the Mediterranean Sea. It is the first of its kind to be based on benthic flux data gathered in situ below fish farms for this particular area. Materials and methods: Samples were collected on four sampling campaigns over a 1-year cycle under a Sparus aurata fish farm facility where benthic fluxes were measured in situ using light and dark benthic chambers. Bottom water and sediment samples were also collected. Data were compared to those for a nearby control station. Results and discussion: Significant differences were found (ANOVA, p < 0. 05) between concentrations of organic matter (OM), total phosphorus and redox potentials in sediments located under the cages and those of the control station. The consumption of dissolved oxygen (DO) by sediment and positive ammonium (NH4 +) fluxes was stimulated by OM content, with correlations of r = -0. 60 (p < 0. 01) and r = 0. 70 (p < 0. 01), respectively. The OM content of sediments was found to be consistently higher under the cages than at the control station, with the highest value (1. 8 ± 0. 7 %) under the cages observed during the early summer; values of DO and NH4 + fluxes were -64 ± 17 and 12. 7 ± 1. 0 mmol m-2 day-1, respectively. PO4 3- fluxes were consistently higher in the fish farm sediments (between 0. 58 and 0. 98 mmol m-2 day-1) than those observed at the control station. Nitrate (NO3 -) fluxes were found to be consistently negative due to denitrification occurring in the sediments and were related to the concentration of NO3 - in bottom waters (r = 0. 92, p < 0. 01). Si fluxes were shown to be associated with water temperature (r = 0. 59, p < 0. 05). Conclusions: The results imply that sediments located below cages accumulate organic matter originating from aquaculture activities, especially during summer months when this activity increases. Sediments undergo biogeochemical changes that mainly affect fluxes of DO, NH4 + and soluble reactive phosphorus, although these do not seem to have a significant impact on the quality of the water column due to the hydrodynamic characteristics of the area. © 2012 Springer-Verlag.We would like to thank the Caja del Mediterraneo for a predoctoral fellowship fund for this research and Antonio Asuncion Acuigroup Maremar manager for the facilities and support in conducting the study. The translation of this paper was funded by the Universidad Politecnica de Valencia, Spain. We are grateful for the valuable comments of the anonymous reviewers on previous versions of the manuscript.Morata Higón, T.; Sospedra, J.; Falco Giaccaglia, SL.; Rodilla Alama, M. (2012). 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Subregional DXA-derived vertebral bone mineral measures are stronger predictors of failure load in specimens with lower areal bone mineral density, compared to those with higher areal bone mineral density

Measurement of areal bone mineral density (aBMD) in intravertebral subregions may increase the diagnostic sensitivity of dual-energy X-ray absorptiometry (DXA)-derived parameters for vertebral fragility. This study investigated whether DXA-derived bone parameters in vertebral subregions were better predictors of vertebral bone strength in specimens with low aBMD, compared to those with higher aBMD. Twenty-five lumbar vertebrae (15 embalmed and 10 fresh-frozen) were scanned with posteroanterior- (PA) and lateral-projection DXA, and then mechanically tested in compression to ultimate failure. Whole-vertebral aBMD and bone mineral content (BMC) were measured from the PA- and lateral-projection scans and within 6 intravertebral subregions. Multivariate regression was used to predict ultimate failure load by BMC, adjusted for vertebral size and specimen fixation status across the whole specimen set, and when subgrouped into specimens with low aBMD and high aBMD. Adjusted BMC explained a substantial proportion of variance in ultimate vertebral load, when measured over the whole vertebral area in lateral projection (adjusted R2 0.84) and across the six subregions (ROIs 2–7) (adjusted R2 range 0.58–0.78). The association between adjusted BMC, either measured subregionally or across the whole vertebral area, and vertebral failure load, was increased for the subgroup of specimens with identified ‘low aBMD’, compared to those with ‘high aBMD’, particularly in the anterior subregion where the adjusted R2 differed by 0.44. The relative contribution of BMC measured in vertebral subregions to ultimate failure load is greater among specimens with lower aBMD, compared to those with higher aBMD, particularly in the anterior subregion of the vertebral body

A study on the fattening traits of Sonmez type lambs

WOS: 000177741200035This study was conducted to determine the fattening performance of Sonmez type lambs weaned on average at 60 5 days old Sixty lambs were put into four different pens as single males (15) single females (15) twin males (15) and twin females (15) and the fattening period was 56 days in length The daily weight gains were 282 14 g 242 49 g 207 31 g and 179 99 g for single males single females twin males and twin females respectively The average daily weight gain in Sonmez type lambs was 227 98 g Feed efficiency levels in Sonmez lambs were 3 98 4 32 4 49 and 4 63 for single males single females twin males and twin females respectively The average feed efficiency value in Sonmez type lambs was found to be 4 35

Map view restoration of Aegean–West Anatolian accretion and extension since the Eocene

The Aegean region (Greece, western Turkey) is one of the best studied continental extensional provinces. Here, we provide the first detailed kinematic restoration of the Aegean region since 35 Ma. The region consists of stacked upper crustal slices (nappes) that reflect a complex paleogeography. These were decoupled from the subducting African-Adriatic lithospheric slab. Especially since !25 Ma, extensional detachments cut the nappe stack and exhumed its metamorphosed portions in metamorphic core complexes. We reconstruct up to 400 km of trench-perpendicular (NE-SW) extension in two stages. From 25 to 15 Ma, the Aegean forearc rotated clockwise relative to the Moesian platform around Euler poles in northern Greece, accommodated by extensional detachments in the north and an inferred transfer fault SE of the Menderes massif. The majority of extension occurred after 15 Ma (up to 290 km) by opposite rotations of the western and eastern parts of the region. Simultaneously, the Aegean region underwent up to 650 km of post-25 Ma trench-parallel extension leading to dramatic crustal thinning on Crete. We restore a detachment configuration with the Mid-Cycladic Lineament representing a detachment that accommodated trench-parallel extension in the central Aegean region. Finally, we demonstrate that the Sakarya zone and Cretaceous ophiolites of Turkey cannot be traced far into the Aegean region and are likely bounded by a pre-35 Ma N-S fault zone. This fault became reactivated since 25 Ma as an extensional detachment located west of Lesbos Island. The paleogeographic units south of the Izmir-Ankara-Sava suture, however, can be correlated from Greece to Turkey

Unified cutting force model for turning, boring, drilling and milling operations

A unified cutting mechanics model is developed for the prediction of cutting forces in milling, boring, turning and drilling operations with inserted tools. The insert and its orientation on a reference tool body are mathematically modeled by following ISO tool definition standards. The material and cutting edge geometry-dependent friction and normal forces acting on the rake face are transformed into reference tool coordinates using a general transformation matrix. The forces are further transformed into turning, boring, drilling and milling coordinates by simply assigning operation specific parameters. The unified model is validated in cutting experiments.</p

The effect of metal transfer modes on mechanical properties of 3CR12 stainless steel

The effect of metal transfer modes on mechanical properties of welded 3CR12 stainless steel was investigated. This was achieved by butt welding 10 mm thick plates of 3CR12. The effect of the metal transfer modes on the microstructure and the mechanical properties of the 3CR12 steel was then investigated as it was hypothesized that the change in welding positions will affect the transfer modes partly because of gravity. The microscopic examination revealed that the substrate was characterized by dual phase microstructure. Using the spectroscopic examination results, the ferritic factor calculation had shown that the microstructure was expected to be ferritic–martensitic during air cooling process. The tensile strength and Charpy impact energy were measured to be 498 MPa and 102 J, respectively. The heat input in the material was observed to be greater than 1 kJ/mm, which is the limiting factor for grain growth. Grain growths were observed in the heat affected zone of the welded materials. Ferritic–martensitic microstructure was observed in the microstructure. The grain growth altered the mechanical properties of the test material. Globular down hand had higher mechanical properties than spray down hand. Globular vertical up had better mechanical properties than globular vertical down. </jats:p