Reduced basis method for managed pressure drilling based on a model with local nonlinearities

To circumvent restrictions of conventional drilling methods, such as slow control actions and inability to drill depleted reservoirs, a drilling method called managed pressure drilling (MPD) has been developed. In MPD, single-phase flow processes can be modeled as a feedback interconnection of a high-order linear system and a low-order nonlinear system. These nonlinearities appear locally both inside and at the boundaries of the computational domain. To obtain a fast simulation platform for real-time purposes (eg, online model-based controller implementation), model order reduction is required for MPD. However, the local nonlinearities render applying model order reduction techniques challenging. In this study, a new approach is proposed to deal with such nonlinearities within the reduced basis (RB) context and it is successfully tested on a model for MPD. Contrary to the classical RB technique, the proposed approach not only does not generate nonphysical spikes at the locations of these local nonlinearities but also yields high speedup factors. The obtained reduced-order model can be used for efficient online simulation and controller design for drilling systems with MPD.     

Experimentelle Ermittlung der Ölströmung in tauchgeschmierten Schneckengetrieben

Forschung im Ingenieurwesen - Schneckengetriebe finden sich in verschiedenen Anwendungen als Stell- und Leistungsgetriebe. Aufgrund der Realisierbarkeit einer hohen Übersetzung bei kleinem...     

Piezoelectricity in Monolayer Hexagonal Boron Nitride

2D hexagonal boron nitride (hBN) is a wide-bandgap van der Waals crystal with a unique combination of properties, including exceptional strength, large oxidation resistance at high temperatures, and optical functionalities. Furthermore, in recent years hBN crystals have become the material of choice for encapsulating other 2D crystals in a variety of technological applications, from optoelectronic and tunneling devices to composites. Monolayer hBN, which has no center of symmetry, is predicted to exhibit piezoelectric properties, yet experimental evidence is lacking. Here, by using electrostatic force microscopy, this effect is observed as a strain-induced change in the local electric field around bubbles and creases, in agreement with theoretical calculations. No piezoelectricity is found in bilayer and bulk hBN, where the center of symmetry is restored. These results add piezoelectricity to the known properties of monolayer hBN, which makes it a desirable candidate for novel electromechanical and stretchable optoelectronic devices, and pave a way to control the local electric field and carrier concentration in van der Waals heterostructures via strain. The experimental approach used here also shows a way to investigate the piezoelectric properties of other materials on the nanoscale by using electrostatic scanning probe techniques.     

Energy efficiency of fibre reinforced soil formation at small element scale: Laboratory and numerical investigation

This paper explores the aspects related to the energy consumption for the compaction of unreinforced and fibre reinforced samples fabricated in the laboratory. It is well known that, for a fixed soil density, the addition of fibres invariably results in an increased resistance to compaction. However, similar peak strength properties of a dense unreinforced sample can be obtained using looser granular soil matrices mixed with small quantities of fibres. Based on both experimental and discrete element modelling (DEM) procedures, this paper demonstrates that less compaction energy is required for building loose fibre reinforced sand samples than for denser unreinforced sand samples while both samples show similar peak strength properties. Beyond corroborating the macro-scale experimental observations, the result of the DEM analyses provides an insight into the local micro-scale mechanisms governing the fibre-grain interaction. These assessments focus on the evolution of the void ratio distribution, re-arrangement of soil particles, mobilisation of stresses in the fibres, and the evolution of the fibre orientation distribution during the stages of compaction.     

丹尼尔斯大厦 加拿大多伦多

正多伦多大学丹尼尔斯建筑、景观和设计学院的设计采用了分期的方法,包括修复和扩建以前称为知识学院的标志性建筑,将现有建筑物改造成与教学和需求更相关的框架体系。这个十九世纪遗址的总体规划是通过对预期用途模式和场地生态的分析而制定的,目的是重新定位校园西南角与安大略湖的轴线,并为学院创造新的特性。丹尼尔斯建筑、景观和设计学院需要一个可持续发展的新型工     

Reactive spark plasma sintering of Cs-exchanged chabazite: characterisation and durability assessment for Fukushima Daiichi NPP clean-up

ABSTRACT

Ion-specific media (ISM) have played an integral role in the clean-up and remediation efforts at the Fukushima Dai-ichi disaster site, through the processing of contaminated wastewaters. The use of these materials generates a secondary nuclear waste stream, presenting its own series of engineering problems arising from stringent handling and long-term storage requirements. A reactive spark plasma sintering (SPS) method was investigated for conditioning of the spent cesium exchanged zeolite, chabazite. A natural form of the zeolite was used as an analogue to the engineered ISM used at the Fukushima NPP site. Simulant wasteforms were sintered using different temperature and pressure parameters followed by analysis of phase assemblage, density, and durability (using the product consistency test (PCT)). The results indicated that zeolite structure had collapsed completely, with the exchanged cesium partitioned primarily into a durable feldspar to assure stability of the sintered material for passively safe storage or geological disposal.     

Emulsion characteristics of salad dressings as affected by caprine whey protein concentrates

Caprine whey protein concentrates (WPC) were incorporated as emulsifiers in a salad dressing. The concentrates were manufactured by ultrafiltration-diafiltration with or without previous clarification by thermocalcic precipitation. Aggregates obtained in the clarification treatment and a commercial bovine WPC were also used as emulsifiers. Good emulsifying properties of caprine products were observed. Dressings made with caprine products showed higher firmness and stability than dressings made with bovine WPC. Thermocalcic precipitation improved the properties of caprine WPC. Aggregates modified the colour of dressings contributing to a more yellowish aspect. Microstructure of emulsions was affected by the type of protein.     

Psychometric evaluation of the Reasons for Living Inventory.

Examined the factor structure and psychometric properties of the Reasons for Living Inventory (RFL; M. M. Linehan et al; see record 1983-20123-001) in a sample of college students with a range of suicidal ideation and behaviors. An exploratory factor analysis of the 48-item RFL extracted 6 factors, similar to those described by Linehan et al. All coefficients alpha and item–subscale correlations were adequate. Additional nonclinical normative data are presented. Multivariate analysis of variance (MANOVA) identified 3 significant discriminant functions for group separation. Correlational analyses provided information about the relationships between the RFL and other self-report measures of suicide risk and general psychopathology. Three RFL subscales were useful in predicting suicide risk and general psychopathology. Limitations and future research issues are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cellular retinyl esters and retinol among parenchymal and stellate cells in normal rat liver

[11,12-³H] Retinyl acetate (100 μg/20 μCi/rat) in corn oil was fed by stomach tube to normal male Wistar-Furth rats (∼250 g body weight). After 15 days, the contents of retinyl esters and retinol (total retinol) and their³H-radioactivity were measured in the whole liver, crude parenchymal cells and the purified parenchymal cells, employing differential centrifugation, centrifugal elutriation and high performance liquid chromatography (HPLC) techniques. Of the total liver retinol (nmol/g liver), the crude parenchymal cells had nearly 90%, whereas the purified parenchymal cells had only 21% based on HPLC analysis. Furthermore, of the total liver retinol radioactivity (dpm/g liver) the crude parenchymal cell fraction had 85%, while the purified parenchymal cell fraction had only 16%. Based on the cell number, the crude parenchymal cell fraction was contaminated by retinoid-rich stellate cells to the extent of 4%. It, therefore, was concluded that the parenchymal cells accounted for 16–21%, whereas the stellate cells contributed 79–84% of total retinol stored in the liver under normal steady-state conditions. It also was calculated that on a per mg basis, stellate cells had 200 times more total retinol than parenchymal cells, whereas on a per cell basis each stellate cell had 74 times more total retinol than a parenchymal cell.