| 1. |
- Amin, Hadi, et al.
(author)
-
A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters
- 2019
-
In: Journal of Geodesy. - : Springer Science and Business Media LLC. - 0949-7714 .- 1432-1394. ; 93:10, s. 1943-1961
-
Journal article (peer-reviewed)abstract
- The geoid, according to the classical Gauss–Listing definition, is, among infinite equipotential surfaces of the Earth’s gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2 s−2 and the semi-major and minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3 s−2.
|
|
| 2. |
- Jansen, Sven, et al.
(author)
-
Validation Results
- 2008
-
Reports (other academic/artistic)abstract
- This report describes the validation of the SASPENCE driver support system using an evaluation method which has been developed within the scope of the SAfe SPEed and safe distaNCE (SASPENCE) project. SASPENCE aims to develop a driver support system that focuses on keeping a safe speed and safe heading distance in relation to other road users and road infrastructure. The system warns the driver to adapt to the situation and consequently the driver actions are influencing the effectiveness of SASPENCE. The Human Machine Interface design has therefore been a key aspect in the development of the system. The developed evaluation method is capable of dealing with a large variation of circumstances (including driver behaviour) and in all steps of the evaluation (apart from straightforward hardware tests) the driver is considered. The evaluation method consists of simulation-based functional tests, on-road functional tests, on-road subjective tests, and traffic impact assessment using simulation. The simulation-based functional tests (using a driver model) have been undertaken in three stages using a probabilistic method to cope with the large variation of circumstances. In the first stage a large number of Monte Carlo simulations were performed to assess the effectiveness of the basic SASPENCE algorithm, and to identify the most critical situations. In the second stage, Software-in-the-Loop simulations have been used to reduce the number of critical situations in order to arrive at a practical number of Hardware-in-the-Loop (HIL) experiments. The HIL experiments confirmed the effectiveness of the results of Monte Carlo simulations, and they additionally provided estimates for dependability parameters (i.e. Safety, Reliability, Appropriateness and Timeliness). On-road functional tests addressed conditions that can not be realised in HIL experiments; however, Appropriateness and Timeliness could not be determined. On-road subjective tests have been carried out in Spain and Italy by selecting 20 drivers at each location and letting each driver run a 50 km course with and without the SASPENCE system activated. Both experimental vehicles were equipped with systems for monitoring the driving session, recording camera images and vehicle motion data. Moreover, the Wiener Fahrprobe in-car observation method was used for the analysis of driver behaviour during the tests. From the users’ point of view, the system has been positively rated as being useful and well accepted by drivers, to an extent that the majority would be willing to pay up to 500 Euro to have it installed in their own vehicle. Also, from the experts’ point of view, the system was rated positively as for instance the number of conflicts and the number of events related to individual behavioural aspects decreased. The recorded vehicle data also confirmed the effectiveness of the system to reduce speed and increase heading distance. The Traffic impact assessment simulations show that the impact of SASPENCE is most apparent for high congestion levels where the positive (safety) effect is an increasing Time-to-Collision. However, the large reduction in the mean speed adversely affects traffic throughput.
|
|
| 3. |
- Jää-Aro, Kai-Mikael, et al.
(author)
-
How not to be objective
- 2001
-
In: Collaborative Virtual Environments. - London : Springer London. - 1852332441 - 9781447106852 ; , s. 143-159
-
Book chapter (other academic/artistic)
|
|
| 4. |
- Markendahl, Jan, et al.
(author)
-
Operator Cooperation as a Competitive Advantage for Provisioning of Low Cost High Capacity Mobile Broad band Services
- 2008
-
In: 19th European Regional ITS Conference.
-
Conference paper (peer-reviewed)abstract
- Operator utility is related to expected profits, risks and strategic issues. In this paper we focus on the potential change in operator utility from network cooperation. If network cooperation would increase operator utility significantly, that would be an important driver of cooperation. We show that the most important effect of network cooperation would be increased user utility, which in turn is shown to have significant impact on operator utility. The user utility is compared without and with cooperation between mobile operators. The user utility is expressed as a User Satisfaction Index (USI) which is depending on the service availability, service quality and the price. Cooperation in the form of sharing of network resources is usually seen as a way to share costs and risk for network deployment. However, there are other operator benefits: improved network utilization and increased traffic which may increase the revenues improved user satisfaction due to improved service availability and quality The network related property of cooperation to reduce the number of disconnected users is transformed into a higher degree of user satisfaction. This would most likely result in more loyal customers and hence the churn would be reduced. In this paper we discuss the implications of the increased user satisfaction on operator costs for customer acquisition and management. We see business opportunities for mobile operators leading to cost savings and changes in the cost structure.
|
|
| 5. |
|
|
| 6. |
- Zaher, Mahmoud, et al.
(author)
-
A Bayesian Approach to Characterize Unknown Interference Power in Wireless Networks
-
Other publication (other academic/artistic)abstract
- The existence of unknown interference is a prevalent problem in wireless communication networks. Especially in multi-user multiple-input multiple-output (MIMO) networks, where a large number of user equipments are served on the same time-frequency resources, the outage performance may be dominated by the unknown interference arising from scheduling variations in neighboring cells. In this letter, we propose a Bayesian method for modeling the unknown interference power in the uplink of a cellular network. Numerical results show that our method accurately models the distribution of the unknown interference power and can be effectively used for rate adaptation with guaranteed target outage performance.
|
|
| 7. |
- Gomez, Maria, et al.
(author)
-
Opposing actions of inositol 1,4,5-trisphosphate and ryanodine receptors on nuclear factor of activated T-cells regulation in smooth muscle
- 2002
-
In: Journal of Biological Chemistry. - 1083-351X. ; 277:40, s. 37756-37764
-
Journal article (peer-reviewed)abstract
- The nuclear factor of activated T-cells (NFAT), originally identified in T-cells, has since been shown to play a role in mediating Ca(2+)-dependent gene transcription in diverse cell types outside of the immune system. We have previously shown that nuclear accumulation of NFATc3 is induced in ileal smooth muscle by platelet-derived growth factor in a manner that depends on Ca(2+) influx through L-type, voltage-dependent Ca(2+) channels. Here we show that NFATc3 is also the predominant NFAT isoform expressed in cerebral artery smooth muscle and is induced to accumulate in the nucleus by UTP and other G(q/11)-coupled receptor agonists. This induction is mediated by calcineurin and is dependent on sarcoplasmic reticulum Ca(2+) release through inositol 1,4,5-trisphosphate receptors and extracellular Ca(2+) influx through L-type, voltage-dependent Ca(2+) channels. Consistent with results obtained in ileal smooth muscle, depolarization-induced Ca(2+) influx fails to induce NFAT nuclear accumulation in cerebral arteries. We also provide evidence that Ca(2+) release by ryanodine receptors in the form of Ca(2+) sparks may exert an inhibitory influence on UTP-induced NFATc3 nuclear accumulation and further suggest that UTP may act, in part, by inhibiting Ca(2+) sparks. These results are consistent with a multifactorial regulation of NFAT nuclear accumulation in smooth muscle that is likely to involve several intracellular signaling pathways, including local effects of sarcoplasmic reticulum Ca(2+) release and effects attributable to global elevations in intracellular Ca(2+).
|
|
| 8. |
|
|
| 9. |
- Gunnarsson, Åsa, 1958-
(author)
-
Skatterättvisa
- 1995
-
Doctoral thesis (other academic/artistic)abstract
- An equitable distribution of the tax burden is a fundamental value in the justification of the tax law. The concrete application of theoretical principles for an equitable distribution of the tax burden takes place in tax legislation through applying principles of law of the ethical and social policy categories. The concrete application of an efficient allocation of resources takes place by applying principles of law establishing neutrality of taxation. These fundamental principles of law therefore act as a meeting point between the basic values and objectives of the legislation on the one hand and the legal rules such as they are formed by statutes and case law on the other hand. Concepts as central in this context as those of equitable distribution and the efficient allocation of resources represent two different aspects on the function of the public economy. In certain contexts these concepts may even be conflicting.The purpose of this dissertation is to analyze the principles of an equitable distribution of the tax burden. This is done from the perspective of the theories of law and of taxation. The intention has also been to study the normative influence of these legal principles on the definition of the tax bases for income tax, net wealth tax, and consumption taxes. Moreover, some light will be shed on the contradiction between certain principles of equity and the principle of neutrality of taxation in relation to the more general objective of efficiency in the national economy.The analysis shows the legislators’ difficulties in upholding normative coherence when transforming principles into legislation. Sometimes the equity principles are used more as a legitimizing front than as a guide for establishing the material contents of the tax law.
|
|
| 10. |
- Jansen, Slinger, et al.
(author)
-
Working Group on Health Measurement of Open Source Projects and Ecosystems
- 2018
-
In: Software Business, Platforms, and Ecosystems.
-
Conference paper (other academic/artistic)abstract
- Open source projects and ecosystems can be studied due to the public availability of their data. The main reasons for studying this data is to collect operationalizable metrics that can be used for the improvement of the project or ecosystem. We can for instance use these metrics to do prediction, study adoption rates, and perform scenario modeling. Presently, in literature, the reigning health factors that are acknowledged are Robustness, Productivity, Niche creation. It is also common to look at ecosystem health from two dimensions: the partner/network level versus the system/project level. Each dimension provides a unique perspective on open source health and enables improvement in a different manner: one focuses on the activity within the platform, whereas the other focuses on the activity outside of it. Typically, in open source ecosystem health research the metrics are characterized along several axes: they are evaluated for availability, collectability, generalizability, comparability, user friendliness, etc. Examples of metrics are interactions between developers, clones, branches, and numbers of commits. We also find that metrics that are typically easy to collect are not very meaningful. Also, the need arises for a meaningful compact subset of metrics, instead of throwing the kitchen sink at evaluation projects. Also, we suspect that “typical” developer behaviors can be extracted from the correlations between different metrics. Finally, we find that the goal-question-metric approach is insufficiently employed in the study of the health of ecosystems. One of the bigger challenges in assessing ecosystem health is the myriad of perspectives on ecosystems. For instance, we can look at network health versus economic health. Furthermore, ecosystems themselves are made up of ecosystems, and we need to establish beforehand what the best manner is of decomposing an ecosystem.
|
|
