4,767 research outputs found
Overcoming Scarcities Through Innovation: What Do Technologists Do When Faced With Constraints?
The question that still divides many debates about sustainability is the possibility of technological substitution of scarce natural resources. While there is considerable debate among economists whether technology can mitigate scarcities through development of substitutes, there is little actual research on the mechanisms and limitations of this substitution process. In this study, I seek to build a bridge between scarcity and innovation literatures to study when technologists decide to develop technological substitutes. My starting point is the theory of technology as a recombination of existing mental and physical components. Combining this theory with modern scarcity literature that differentiates between absolute, relative, and quasi-scarcities yields a more nuanced framework for understanding both different types of scarcities, and how technologists decide whether or not to develop or adopt technological substitutes. This improves our understanding of the possibilities — and limitations — of scarcity-induced innovation. I then illustrate the use of this framework with two brief historical case studies about constraint-induced innovation. I conclude that the mainstream economic practice of assuming that substitution will occur automatically, even in cases of absolute scarcity, may hide extremely important phenomena from discussion and debate behind a veil of circular reasoning.</p
Tolerating the intolerable: Flash smelting of copper and the construction of technological constraints
The history of Outokumpu flash furnace and the construction of electricity constraints.</p
Ternary nucleation of H_2SO_4, NH_3 and H_2O
A classical theory of the ternary homogeneous nucleation of sulfuric acid—ammonia—water is presented. For NH3 mixing ratios exceeding 1 ppt, the presence of ammonia enhances the binary (sulfuric acid—water) nucleation rate by several orders of magnitude. However, the limiting component for ternary nucleation—as for binary nucleation—is sulfuric acid. The sulfuric acid concentration needed for significant ternary nucleation is several orders of magnitude below that required in binary case
A search for flares and mass ejections on young late-type stars in the open cluster Blanco-1
We present a search for stellar activity (flares and mass ejections) in a
sample of 28 stars in the young open cluster Blanco-1. We use optical spectra
obtained with ESO's VIMOS multi-object spectrograph installed on the VLT. From
the total observing time of 5 hours, we find four H flares but
no distinct indication of coronal mass ejections (CMEs) on the investigated
dK-dM stars. Two flares show "dips" in their light-curves right before their
impulsive phases which are similar to previous discoveries in photometric
light-curves of active dMe stars. We estimate an upper limit of 4 CMEs per
day per star and discuss this result with respect to a semi- empirical
estimation of the CME rate of main-sequence stars. We find that we should have
detected at least one CME per star with a mass of 1-15 g
depending on the star's X-ray luminosity, but the estimated H fluxes
associated with these masses are below the detection limit of our observations.
We conclude that the parameter which mainly influences the detection of stellar
CMEs using the method of Doppler-shifted emission caused by moving plasma is
not the spectral resolution or velocity but the flux or mass of the CME.Comment: Accepted for publication in MNRAS, accepted 2014 June 10, received
2014 June 5, in original form 2014 March 24, 14 pages, 5 figure
First measurement of the magnetic field on FK Com and its relation to the contemporaneous starspot locations
In this study we present simultaneous low-resolution longitudinal magnetic
field measurements and high-resolution spectroscopic observations of the cool
single giant FK Com. The variation of the magnetic field over the rotational
period of 2.4 days is compared with the starspot location obtained using
Doppler imaging techniques, V-band photometry and V-I colours. The
chromospheric activity is studied simultaneously with the photospheric activity
using high resolution observations of the Halpha, Hbeta and Hgamma line
profiles. Both the maximum (272 +/- 24 G) and minimum (60 +/- 17 G) in the mean
longitudinal magnetic field, , are detected close to the phases where cool
spots appear on the stellar surface. A possible explanation for such a
behaviour is that the active regions at the two longitudes separated by 0.2 in
phase have opposite polarities.Comment: 10 Pages, 11 figures (quality of Figures 7,8 and 10 reduced),
accepted for publication in MNRA
Practical Aspects of Value Efficiency Analysis
In this paper, we consider practical aspects for measuring Value Efficiency in Envelopment Analyis. Value efficiency is an efficiency concept that takes into account the decision maker's preferences.It was developed by Halme, Joro, Korhonen, Salo and Wallenius [1998]. The decision maker is asumed to compare alternatives using an implicitly known value function which reaches its maximum at the most preferred point on the efficient frontier. The unknown value function is assumed to be pseudoconcave and strictly increasing for outputs and strictly decreasing for inputs. The purpose of value effiiency analysis is to estimate a need to increase outputs and/or decrease inputs for reaching the indifference contour of the value function at the optimum. Because the value function is unknown, the indifference contours cannot be defined precisely. Value efficiency analysis never results in more pessimistic evaluation than in the case of a known function. To carry out value efficiency analysis, we have to locate the most preferred solution of the decision maker. In practice, this phase cannot be too complicated. We propose a few alternative ways to locate it and discuss the use of those ways in practical application
Rank Order for a Rehabilitation Program Using Multiple Criteria
In this study we investigate an urban planning problem where an area is to be rehabilitated. The area is divided into several sub-areas any of which could be the starting point for the rehabilitation process. The ultimate goal is to find a rank order for the alternative sub-areas, which simultaneously solves the problem of where to start the rehabilitation. If all information are given on the ordinal scale, we could use e.g. the classical minimum violation principle to solve this problem. In this paper, we have generalized this approach to cover the cardinal scale and pairwise information
Stellar activity as noise in exoplanet detection I. Methods and application to solar-like stars and activity cycles
The detection of exoplanets using any method is prone to confusion due to the
intrinsic variability of the host star. We investigate the effect of cool
starspots on the detectability of the exoplanets around solar-like stars using
the radial velocity method. For investigating this activity-caused "jitter" we
calculate synthetic spectra using radiative transfer, known stellar atomic and
molecular lines, different surface spot configurations, and an added planetary
signal. Here, the methods are described in detail, tested and compared to
previously published studies. The methods are also applied to investigate the
activity jitter in old and young solar-like stars, and over a solar-like
activity cycles. We find that the mean full jitter amplitude obtained from the
spot surfaces mimicking the solar activity varies during the cycle
approximately between 1 m/s and 9 m/s. With a realistic observing frequency a
Neptune mass planet on a one year orbit can be reliably recovered. On the other
hand, the recovery of an Earth mass planet on a similar orbit is not feasible
with high significance. The methods developed in this study have a great
potential for doing statistical studies of planet detectability, and also for
investigating the effect of stellar activity on recovered planetary parameters.Comment: Accepted to MNRA
Abundance analysis, spectral variability, and search for the presence of a magnetic field in the typical PGa star HD19400
The aim of this study is to carry out an abundance determination, to search
for spectral variability and for the presence of a weak magnetic field in the
typical PGa star HD19400. High-resolution, high signal-to-noise HARPS
spectropolarimetric observations of HD19400 were obtained at three different
epochs in 2011 and 2013. For the first time, we present abundances of various
elements determined using an ATLAS12 model, including the abundances of a
number of elements not analysed by previous studies, such as Ne I, Ga II, and
Xe II. Several lines of As II are also present in the spectra of HD19400. To
study the variability, we compared the behaviour of the line profiles of
various elements. We report on the first detection of anomalous shapes of line
profiles belonging to Mn and Hg, and the variability of the line profiles
belonging to the elements Hg, P, Mn, Fe, and Ga. We suggest that the
variability of the line profiles of these elements is caused by their
non-uniform surface distribution, similar to the presence of chemical spots
detected in HgMn stars. The search for the presence of a magnetic field was
carried out using the moment technique and the SVD method. Our measurements of
the magnetic field with the moment technique using 22 Mn II lines indicate the
potential existence of a weak variable longitudinal magnetic field on the first
epoch. The SVD method applied to the Mn II lines indicates =-76+-25G on
the first epoch, and at the same epoch the SVD analysis of the observations
using the Fe II lines shows =-91+-35G. The calculated false alarm
probability values, 0.008 and 0.003, respectively, are above the value 10^{-3},
indicating no detection.Comment: 13+6 pages, 14 figures, 6+1 tables, including the online-only
material, accepted for publication in MNRA
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