2,538 research outputs found
Business Model Performance: Paving the road for comparable data on business models
Attempting to close the gap of missing available quantitative data on business models, we identify value creation patterns, which may be interpreted as personality tests of companies’ value creation. It is our intention to explain the notion of using value drivers to create links between different business models and performance measurement
Procedure to Approximately Estimate the Uncertainty of Material Ratio Parameters due to Inhomogeneity of Surface Roughness
Roughness parameters that characterize contacting surfaces with regard to
friction and wear are commonly stated without uncertainties, or with an
uncertainty only taking into account a very limited amount of aspects such as
repeatability of reproducibility (homogeneity) of the specimen. This makes it
difficult to discriminate between different values of single roughness
parameters.
Therefore uncertainty assessment methods are required that take all relevant
aspects into account. In the literature this is scarcely performed and examples
specific for parameters used in friction and wear are not yet given.
We propose a procedure to derive the uncertainty from a single profile
employing a statistical method that is based on the statistical moments of the
amplitude distribution and the autocorrelation length of the profile. To show
the possibilities and the limitations of this method we compare the uncertainty
derived from a single profile with that derived from a high statistics
experiment.Comment: submitted to Meas. Sci. Technol., 12 figure
Tillage in the growing season is ineffective as a tool of increased soil N mineralization
Soil tillage serves a number of purposes such as control of weeds, incorporation of crop residues and manures, and maintenance or improvement of soil mechanical properties, including seedbed preparations. As a side-effect, soil tillage may affect turnover of organic matter (OM) by changing the particle size and spatial distribution of crop and manure residues in soil and by increasing the intimacy of residue/soil contacts. By breaking soil structural elements, tillage may contribute further to N mineralization by exposing physically protected organic matter to microbial turnover. Therefore, adjusting the time, intensity and frequency of soil tillage operations may enable optimization of synchrony, defined as the matching through time of N availability and crop N demand. This idea was experimentally investigated in the present study
Herd-level risk factors associated with cow mortality in Swedish dairy herds
An increase in on-farm mortality (euthanasia and death) in dairy herds has been reported in several countries in the last decade. This does not only imply possible problems with animal welfare, but it also causes economic losses to the farmer. The objective of this study was to evaluate time trends in on-farm dairy cow mortality in Sweden and identify potential herd-level risk factors. Data was retrieved on all Swedish dairy herds enrolled in the milk recording scheme between 2002 and 2010. Herds with a herd size of 40 dead or euthanized cows per 100 cow-years were excluded. Two different models were used: 1 multiple year analysis which included 6,898 herds during the period 2002 to 2010 and 1 single year analysis including 4,252 herds for the year 2010, where other variables that were not present during the entire multiple year study were analyzed. The outcome variable was the number of euthanized and dead cows per year and season. A negative binomial regression model, adjusted for clustering within herd, was applied to both models. Fixed effects in the multiple year analysis were breed, calving interval, herd size, milk yield, region, season, pasture period, and year. Fixed effects in the single year analysis were breed, calving interval, conventional vs. organic farming, herd size, housing system, milk yield, region, and season. The multiple year analysis demonstrated that MR gradually increased from 5.1 to 6.6 events per 100 cow-years during the study period. Swedish MR are consequently on par with, or even greater than, MR among dairy herds in other comparable countries. Higher mortality was associated with larger herd size, longer calving intervals, and herds that had Swedish Holstein as the predominant breed. Lower mortality was observed in herds with a higher herd average milk yield, during the fall and winter, and in organically managed herds. There were regional differences in mortality. An interaction between herd size and season was found in both models. Also, an interaction between housing system and milk yield was found in the single year analysis. This first assessment of on-farm mortality in Swedish dairy herds confirmed that the MR has increased over the last few years. The study also identified some herd-level risk factors
Jordløsning i vækstsæsonen øger ikke N mineraliseringenen
Jordbearbejdning foretages almindeligvis for at klargøre jorden til såning eller for at nedmulde planterester og gødning.
Ligeledes kan jordbearbejdning finde sted både i og uden for vækstsæsonen i forbindelse med mekanisk ukrudtsbekæmpelse.
Der er en udbredt opfattelse af, at ukrudtsbekæmpelse, foretaget fx ved radrensning af rækkeafgrøder i vækstsæsonen, også øger mineraliseringen af kvælstof. En øget kvælstofmineralisering formodes at finde sted som følge af, at den mekaniske bearbejdning bryder jordknolde, hvorved der blotlægges organisk materiale, som nedbrydes. Samtidigt fremmer jordbearbejdningen luftskiftet i jorden, og betingelserne for omsætning forventes dermed forbedrede.
En øget kvælstofmineralisering som følge af jordbearbejdning ville åbne mulighed for at styre kvælstoffrigivelsen i forhold til en afgrødes vækst. Potentialet for dette er undersøgt i vinterhvede, hvor det blev testet, om jordløsning kunne gøre det ud for en sengødskning med kvælstof
- …