| 1. |
- Aad, G., et al.
(författare)
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- 2012
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Tidskriftsartikel (refereegranskat)
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| 2. |
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Översyn av nationell akvatisk miljögiftsövervakning 2014 : Programområden Sötvatten och Kust och hav
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Under 2013-2014 har Naturvårdsverket genomfört en översyn av nationell miljögiftsövervakning inom programområdena Kust och hav och Sötvatten, denna har genomförts parallellt med Havs- och Vattenmyndighetens övergripande revision av dessa båda programområden.Fokus på översynen har varit att se över gamla, nya och kommande övervakningskrav för de ämnes- och effektparametrar (indikatorer) som förekommer inom vatten- och havsmiljöförvaltning samt inom havskonventionerna. Naturvårdsverket har bedömt vilka parametrar som är aktuella för nationell övervakning, vilka brister i övrigt som finns i dagens nationella övervakning, samt tagit fram förslag till åtgärder och förbättringar.
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| 3. |
- Ridderstedt, Ivan, 1990-
(författare)
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Improving the Efficiency of Public Procurement : Empirical evidence using micro-level contract data
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Among OECD countries, close to one-third of government expenditure is allocated using public procurement. This implies that the skill of public authorities in handling the procurement format has a significant impact on how much the public sector accomplish in relation to their goals and responsibilities. The aim of this thesis is to provide new insights into how public procurers can achieve more for the money by improving the design of their auctions and contracts. Specifically, the thesis examines how the efficiency can be influenced by the following three aspects: the method of bid evaluation (the award mechanism), whether items are procured separately or grouped into larger contracts, and variations among procurers in the activities and quantities they specify in a given case.The thesis includes four essays that analyze detailed contract information from Swedish procurements of road reinvestments and public bus services. For a comprehensive sample of the examined contracts, information has been collected from procurement documents and compiled into rich microdata sets. The use of microdata has enabled detailed reviews of how the procurements have been designed as well as statistical analysis of associations between the procurer’s choices and the outcome. While the essays primarily focus on results and implications regarding their respective research questions, the kappa provides a more general discussion about quantitative microanalysis in the field of procurement. This reflects a complementary aim of the thesis, which is to contribute to well-informed decisions regarding whether and how contracting authorities should facilitate analyses of this kind.Two of the essays investigate to what extent and how the Swedish national infrastructure manager Trafikverket can improve its efficiency in procurements of highway pavement replacement. Trafikverket spends approximately EUR 200 million on these works annually. Hence, if better procurement methods could lower the cost by 5% without reducing the quality, about EUR 10 million would be freed up annually for additional road maintenance or other uses. Both essays indicate that even greater efficiency gains can be achieved through improved dissemination of best practices. The results support Trafikverket's policy to bundle similar and adjacent road work but imply that the contracts are generally not large enough to fully benefit from the economies of scale. A conclusion is that it is motivated for Trafikverket to consider the scope for efficient bundling when deciding on the timing of these pavement replacement measures.The other two essays examine how the Swedish regional Public Transport Authorities (PTAs) have implemented the scoring rule award mechanism and its efficiency. This alternative to the lowest price and quality-only mechanisms is promoted within the EU procurement directive and is dominant in many countries. However, the literature on how well public agencies implement this policy is scarce and fragmented. One of the essays shows that scoring rules are common in Swedish procurements of public bus services, but also that there are significant differences between the PTAs in whether and how they have applied this award mechanism. Several implementations have unsound and likely unintended properties, in the light of economic theory. The findings suggest that best practices are not spread effectively between the organizations. The second essay on this theme exploits the property that one PTA alternated between lowest price and a performance focused variant of scoring rules and, equally important, could provide data on a relevant and reliable outcome measure. Based on 30 months of observations on monitored punctuality, performance is not found to be better in contracts awarded using scoring rules. The results suggest that the promotion of scoring rules is not accompanied with adequate guidance on when and how to implement it efficiently.The kappa highlights how microdata at the contract level enable research that considers both the ‘uniqueness’ of each procurement and random variation. In the analyses of road reinvestments, the detailed data allows us to consider several important characteristics of the contracts and the treated road segments. Similarly, the analysis of bus punctuality considers several aspects of the traffic assignment. In this way, quantitative microanalysis can provide reliable quantifications of how costs and quality are affected by both the procurer's actions, while considering the external conditions. Many of these associations are too complex to be reliably assessed by an individual civil servant, even if it is highly knowledgeable and experienced. However, the thesis emphasizes that even quantitative analysis can yield misleading results if the data material is not good enough, for example, if the sample is too small or relevant aspects are not captured.A central argument in the thesis is that the standardized and rigid procurement process creates particularly excellent conditions for collecting useful procurement data. However, the potential for this has largely remained untapped by the public agencies themselves. Instead, these data have primarily been compiled within individual research projects, where even the collection of tendering documents has been a notorious obstacle. In Sweden, Trafikverket's information management and cost control have repeatedly been criticized. However, Trafikverket is far from the ‘worst in class’ in these matters, and the criticism mainly reflects the agency's position as one of Sweden's largest procurers. An overall conclusion of the thesis is that public agencies in general should take a more active role in improving how procurement data are collected and managed. Of particular importance is the establishment of well-structured archiving processes for procurement documents, along with systems to track changes in both costs and content after a contract is awarded. For smaller authorities, it is reasonable that this development is coordinated or driven by a centralized function, whereas Trafikverket is well positioned to take a leading role in finding and disseminating best practices. Ultimately, the responsibility for instructing and overseeing improvements in this area lies with the governing bodies of the public agencies, given that the agencies do not set their own agendas.
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| 4. |
- Thobaben, Ragnar
(författare)
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Joint Network/Channel Coding for Multi-User Hybrid-ARQ
- 2008
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Ingår i: 7th International ITG Conference on Source and Channel Coding (SCC), 2008. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783800730773
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Konferensbidrag (refereegranskat)abstract
- We present a novel multi-user hybrid-ARQ scheme for a wireless multiple-unicast scenario where a base station supplies a group of users with individual messages. Considering that all users have access to noisy observations of all transmitted packets, network coding is applied to combine retransmissions to several users. Within this framework, we propose a novel joint network and channel code design which allows the users to perform iterative network/channel decoding. Simulation results for the Rayleigh block-fading channel show a significant increase in throughput compared to separate decoding while the complexity for the users is greatly reduced at the same time.
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| 5. |
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| 6. |
- Arnby, Karl, 1974
(författare)
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Low-Temperature Oxidation of CO and Volatile Organic Compounds over Supported Platinum Catalysts
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The catalytic oxidation of carbon monoxide (CO) and volatile organic compounds (VOC) is important for the reduction of harmful emissions from both vehicles and from stationary sources. Both these applications suffer from poor catalytic efficiency at lower temperatures. The objective of this work was to gain a deeper understanding of the low-temperature oxidation of CO and VOC over alumina supported platinum catalysts. The work has been focused on the preparation of platinum-based model catalysts, extensive flow reactor studies and thorough sample characterisation. A new preparation method was used to prepare supported catalysts with platinum distributed locally in high concentrations on the alumina support. The purpose was to prepare catalysts that would retain the evolved reaction heat to a higher extent and thereby become more active at low temperatures than conventionally prepared catalysts. The catalysts prepared using this new method showed an improved low-temperature activity for the oxidation of CO, however, not for the oxidation of propene or propane. When considering heat transfer, calculations of both temporary effects and heat accumulation showed that the enhanced activity for CO oxidation can not be explained by a heat effect. Instead, mass transfer limitations probably improved the activity to a certain extent, and structural effects can also be of importance. The oxidation of propane over Pt/γ-Al2O3 was shown to be highly influenced by the oxygen concentration. Maximum activity was observed close to stoichiometric conditions. At net-oxidising conditions the catalysts were most likely passivated due to formation of platinum oxide. In a deactivation study, the influence of hexamethyldisiloxane (HMDS) on the oxidation of ethyl acetate over iron-promoted Pt/γ-Al2O3 samples was investigated. The catalytic deactivation was found to proceed as HMDS decomposed into silicate (SixOy), which blocks the active sites on the catalyst surface. The poisoning was found to be selective as silicon rather attached to platinum and iron sites than to alumina. Moreover, depending on the catalyst composition the deactivation was either reversible or irreversible. Promoting the Pt/γ-Al2O3 catalyst with iron increased the tolerance towards HMDS as fewer platinum sites were blocked by silicate.
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| 7. |
- Adloff, C, et al.
(författare)
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Diffractive photoproduction of psi(2S) mesons at HERA
- 2002
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 541:3-4, s. 251-264
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Tidskriftsartikel (refereegranskat)abstract
- Results on diffractive photoproduction of psi(2S) mesons are presented using data collected between 1996 and 2000 with the H1 detector at the HERA ep collider. The data correspond to an integrated luminosity of 77 pb(-1). The energy dependence of the diffractive psi(2S) cross section is found to be similar to or possibly somewhat steeper than that for J/psi mesons. The dependences of the elastic and proton dissociative psi(2S) photoproduction cross sections on the squared momentum transfer t at the proton vertex are measured. The t-dependence of the elastic channel, parametrised as e(bt), yields b(el)(psi(2S)) = (4.31 +/- 0.57 +/- 0.46) GeV-2, compatible with that of the J/psi. For the proton dissociative channel the result b(pd)(psi(2S)) = (0.59 +/- 0.13 +/- 0.12) GeV-2 is 2.3 standard deviations smaller than that measured for the J/psi. With proper account of the individual wavefunctions theoretical predictions based on perturbative QCD are found to describe the measurements well. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 8. |
- Adloff, C, et al.
(författare)
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Search for excited electrons at HERA
- 2002
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 548:1-2, s. 35-44
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Tidskriftsartikel (refereegranskat)abstract
- A search for excited electron (e*) production is described in which the electroweak decays e* --> egamma, e* --> eZ and e* ---> nuW are considered. The data used correspond to an integrated luminosity of 120 pb(-1) taken in e(+/-)p collisions from 1994 to 2000 with the H1 detector at HERA at centre-of-mass energies of 300 and 318 GeV. No evidence for a signal is found. Mass dependent exclusion limits are derived for the ratio of the couplings to the compositeness scale, f/A. These limits extend the excluded region to higher masses than has been possible in previous direct searches for excited electrons. (C) 2002 Published by Elsevier Science B.V.
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| 9. |
- Adlmann, Franz, et al.
(författare)
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Normalization of stroboscopic neutron scattering experiments
- 2018
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 434, s. 61-65
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Tidskriftsartikel (refereegranskat)abstract
- Neutron scattering studies of kinetic processes are often flux limited. For processes which can be repeated many times, this can be mitigated by stroboscopic reintegration. The recorded scattering events are assigned to different time slices of the process and corresponding slices from all repetitions are summed up. The normalization of such data with respect to the incident beam spectrum can be challenging since the incident neutron flux may not necessarily be evenly distributed over all time slices. In this paper, we discuss how this can result in misleading information and we expand on a technique to amend these issues.
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| 10. |
- Adloff, C, et al.
(författare)
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Measurement of D*(+/-) meson production and F-2(c) in deep-inelastic scattering at HERA
- 2002
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 528:3-4, s. 199-214
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Tidskriftsartikel (refereegranskat)abstract
- The inclusive production of D*+/-(2010) mesons in deep-inelastic scattering is studied with the HI detector at HERA. In the kinematic region 1 < Q(2) < 100 GeV2 and 0.05 < y < 0.7 an e(+) p cross section for inclusive D*+/- meson production of 8.50 +/- 0.42(stat.)(-100)(+1.21)(syst.) nb is measured in the visible range p(tD*) > 1.5 GeV and eta(D*) < 1.5. Single and double differential inclusive D*+/- meson cross sections are compared to perturbative QCD calculations in two different evolution schemes, The charm contribution to the proton structure, F-c(2)(x, Q(2)), is determined by extrapolating the visible charm cross section to the full phase space. This contribution is found to rise from about 10% at Q(2) = 1.5 GeV2 to more than 25% at Q(2) = 60 GeV2 corresponding to x values ranging from 5 x 10(-5) to 3 x 10(-3). (C) 2002 Elsevier Science B.V. All rights reserved.
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