Bidding strategies for real-life small loan auctions

We define and identify bidding strategies in real-life small loan auctions (Prosper.com). In such auctions, lenders bid for borrowers' loan listings and the winners get to fund the loan at an interest rate determined by the auction. The exceptionally large empirical database provided by Prosper.com offers a unique opportunity to test and further develop the theory of online auctions. This study shows that bidding behavior is not homogeneous among bidders, as the traditional auction theory suggests. Instead, bidders use many different bidding strategies. Moreover, learning and bidders' consistency over time in different auctions is studied.     

Site managers’ daily work and the uses of building information modelling in construction site management

The use of building information modelling (BIM) and related software tools is increasingly expanding in the work of site managers in construction projects. The early uses of BIM in the actual tasks of site managers are explored by examining the utilization of BIM in their work and the challenges in the deployment of the new digital tools for traditional project collaboration. The ethnographic method of the study consists of shadowing the site managers’ work. The site managers actively used BIM and found it beneficial for their daily work. However, the use of BIM in construction sites is still limited because only a few managers have the competence to use BIM software tools, mobile tools are lacking, and the information content of the models needed for construction work is insufficient.     

Effect of self-etching dual-curing universal adhesive system application on bond strength of dentin resinous liners dentin

Purpose: The aim of this study was to evaluate the influence of previous application of an adhesive system on bond strength of resinous liner materials to dentin. Methods: Ninety bovine incisors crowns had a 6 × 6 mm area of dentin exposed, with minimum of 2 mm thickness. They were embedded in acrylic resin, and the dentin was polished with P600 SiC sandpaper for 30 s to standardize the smear layer. The specimens were divided into 6 groups (n = 15) according to the application or not of a self-etching system (Futurabond U – Voco) and the type of resinous liner used: A+Ionoseal (adhesive and Ionoseal – Voco); Ionoseal (Ionoseal only); A+Vitrebond (adhesive and Vitrebond – 3M/ESPE); Vitrebond (Vitrebond only); A+Ionosit (adhesive and Ionosit – DMG) and Ionosit (Ionosit only). Adhesives were used following manufacturer’s instructions, and the liner materials were applied inside a 2-mm-depth matrix and light-cured for 20 s. The bond strength was measured by microtensile test, using a universal testing machine with a cross-speed of 1 mm/min. Data were analyzed using one-way ANOVA and Tukey’s test (p < 0.05). Results: The adhesive system application increased bond strength of all liners tested. Ionoseal presented the highest bond strength when the adhesive system was used and exhibited similar performance to Vitrebond without adhesive. Ionosit without adhesive showed the smallest bond strength compared with the other liners tested. Conclusion: The application of an adhesive system prior to the use of the resinous liners improved the bond strength to dentin and should be preconized.     

Processing of rye bran influences both the fermentation of dietary fibre and the bioconversion of lignans by human faecal flora in vitro

Plant lignans are converted to mammalian forms, enterodiol and enterolactone, in the colon. Enhanced plasma or urinary enterolactone levels have been associated with lowered risk of cardiovascular diseases and breast cancer. Processed rye bran and its fractions were compared to ascertain the fermentation rates of fermentable carbohydrates and the bioconversion of lignans. Rye bran was extruded and treated with a food‐grade xylanase. Part of the xylanase‐treated rye bran was separated into a soluble rye bran extract and an insoluble residue, and a part of the xylanase‐treated rye bran was freeze‐dried without separation. All the samples were digested by pepsin and pancreatin and subsequently fermented with a human faecal inoculum in vitro. The consumption of carbohydrates, the productions of short‐chain fatty acids (SCFA), enterodiol and enterolactone were followed as a function of time. The soluble rye bran extract showed the fastest fermentation rate and the highest extent of fermentation determined as the consumption of neutral sugar residues (arabinose, xylose and glucose), the production of SCFA and the formation of enterodiol and enterolactone. Xylanase treatment enhanced the fermentation rate of extruded rye bran. An even a higher fermentation rate was observed for rye bran extract containing soluble carbohydrates. The amount of enterolactone precursors in rye seemed to be too low for enterolactone formation using an amount of substrate suitable for carbohydrate fermentation. However, xylanase treatment enhanced the availability of plant lignans from rye bran, as enterodiol formation was increased by the use of xylanase. Copyright © 2005 Society of Chemical Industry     

Hourly wind power variations in the Nordic countries

Studies of the effects that wind power production imposes on the power system involve assessing the variations of large‐scale wind power production over the whole power system area. Large geographical spreading of wind power will reduce variability, increase predictability and decrease the occasions with near zero or peak output. In this article the patterns and statistical properties of large‐scale wind power production data are studied using the data sets available for the Nordic countries. The existing data from Denmark give the basis against which the data collected from the other Nordic countries are benchmarked. The main goal is to determine the statistical parameters describing the reduction of variability in the time series for the different areas in question. The hourly variations of large‐scale wind power stay 91%–94% of the time within ±5% of installed capacity in one country, and for the whole of the Nordic area 98% of the time. For the Nordic time series studied, the best indicator of reduced variability in the time series was the standard deviation of the hourly variations. According to the Danish data, it is reduced to less than 3% from a single site value of 10% of capacity. Copyright © 2004 John Wiley & Sons, Ltd.     

Characteristics of day‐ahead wind power forecast errors in Nordic countries and benefits of aggregation

The growing proportion of wind power in the Nordic power system increases day‐ahead forecasting errors, which have a link to the rising need for balancing power. However, having a large interconnected synchronous power system has its benefits, because it enables to aggregate imbalances from large geographical areas. In this paper, day‐ahead forecast errors from four Nordic countries and the impacts of wind power plant dispersion on forecast errors in areas of different sizes are studied. The forecast accuracy in different regions depends on the amount of the total wind power capacity in the region, how dispersed the capacity is and the forecast model applied. Further, there is a saturation effect involved, after which the reduction in the relative forecast error is not very large anymore. The correlations of day‐ahead forecast errors between areas decline rapidly when the distance increases. All error statistics show a strong decreasing trend up to the area sizes of 50,000 km². The average mean absolute error (MAE) in different regions is 5.7% of installed capacity. However, MAE of a smaller area can be over 8% of the capacity, but when all the Nordic regions are aggregated together, the capacity‐normalized MAE decreases to 2.5%. The average of the largest errors for different regions is 39.8% and when looking at the largest forecast errors for smaller areas, the largest errors can exceed 80% of the installed capacity, whereas at the Nordic level, the maximum forecast error is only 13.5% of the installed capacity. Copyright © 2016 John Wiley & Sons, Ltd.     

Impacts of large amounts of wind power on design and operation of power systems,results of IEA collaboration

There are dozens of studies made and ongoing related to wind integration. However, the results are not easy to compare. IEA WIND R&D Task 25 on ‘Design and Operation of Power Systems with Large Amounts of Wind Power’ collects and shares information on wind generation impacts on power systems, with analyses and guidelines on methodologies. In the state‐of‐the‐art report (October, 2007), and the final report of the 3 years period (July, 2009) the most relevant wind power grid integration studies have been analysed especially regarding methodologies and input data. Several issues that impact on the amount of wind power that can be integrated have been identified. Large balancing areas and aggregation benefits of wide areas help in reducing the variability and forecast errors of wind power as well as help in pooling more cost effective balancing resources. System operation and functioning electricity markets at less than day‐ahead time scales help reduce forecast errors of wind power. Transmission is the key to aggregation benefits, electricity markets and larger balancing areas. Best practices in wind integration studies are described. There is also benefit when adding wind power to power systems: it reduces the total operating costs and emissions as wind replaces fossil fuels and this should be highlighted more in future studies. Copyright © 2010 John Wiley & Sons, Ltd.     

Lipase-catalyzed transesterification of rapeseed oil and 2-ethyl-1-hexanol

Lipase-catalyzed transesterification (alcoholysis) of lowerucic acid rapeseed oil and 2-ethyl-1-hexanol without an additional organic solvent was studied in stirred batch reactors. Of a number of commercially available enzymes investigated, the best results were obtained with aCandida rugosa lipase. The optimal transesterification conditions were an oil/alcohol molar ratio of 1∶2.8, a minimum of 1.0% (w/w) added water, and with a temperature of 37–55°C. Under the optimal conditions, a nearly complete conversion was obtained in one hour with 14.6% (w/w) lipase, whereas 0.3% (w/w) lipase required 10 h for similar results. The enzyme was inactivated at 60°C.     

Assessing the quality of the sampling of fuel peat using computer simulation

A simulation scheme to assess and improve the performance of the sampling of fuel peat is considered. The scheme provides a practical possibility to inspect all possible sources of variation and error. Test results from a district heating plant are reported.     

Physical, chemical and microbiological water characteristics associated with the occurrence of Legionella in cooling tower systems

The occurrence of Legionella in water of 30 cooling tower systems was studied, as well as the relationship of its occurrence with the physical, chemical and microbiological characteristics of the waters. The samples were concentrated by membrane filtration and one part of the concentrate was acid washed. Three types of culture media, MWY, CCVC and BCYEα were used. Fourteen (47%) of the cooling systems were Legionella-positive. Numbers of Legionella in the positive systems varied between 50 and 490,000 cfu/l. Legionella pneumophila was the dominant isolate, and the serogroups 6 and 1 were the commonest ones. There was no statistically significant difference in mean water temperature between the Legionella-positive (27°C) and -negative (24°C) systems. The total number of bacteria (AODC) was lower in the Legionella-positive than in the negative systems. Also the nutrient concentrations were generally lower in the Legionella-positive cooling systems. The results suggest that different factors regulate the occurrence of Legionella than that of overall bacterial populations in the cooling tower systems.