Substitution between fixed, mobile, and voice over IP telephony: Evidence from the European Union

Developments in the EU telecommunications markets require a recurrent redesign of the regulatory framework for telecommunications services. In this regard, the analysis of the substitution effects between different types of telephony is the cornerstone of market definition and therefore of effective regulation. This paper explores the access substitution between fixed-lines, mobiles, and managed VoIP in a unified EU cross-country framework. We employ a half-yearly dataset for 20 EU countries for the 2008-2011 period and apply dynamic panel data methods. Our analysis demonstrates strong access substitution between fixed-lines and mobiles and provides indicative evidence on the substitution between fixed-lines and VoIP. Overall, we find evidence in favor of access substitution and therefore of joint market definition. Regulatory obligations imposed on the market for access to fixed telephone networks might therefore be redundant

Deregulating fixed voice services? Empirical evidence from the European Union

This paper analyzes the relationship between the traditional fixed-line, mobile and Voice over IP (VoIP) telephony in the EU. In doing so, it aims at filling the gap in the empirical literature on the substitution patterns between these technologies in a comprehensive way. It relies on demand estimation for fixed-line telephony using a unique data set comprising 25 EU member states for the 2006:Q2 - 2011:Q4 period. Employing instrumental variable approach, demand-side substitution for VoIP as well as mobile telephony services is found to be prevalent. Estimated short-run own- and cross-price elasticities are in the inelastic range, however, in the long run demand is clearly elastic. Hence, our results underpin the Europeans Commission's current decision to lift the ex ante regulation on the fixed-line telephony market

Deregulating fixed voice services? Empirical evidence from the European Union

This paper deals with the relationship between the traditional fixed-line, mobile and Voice over IP telephony in the EU.We estimate the supply and demand for fixed-line telephony using data on 25 EU member states for the 2006:Q2 - 2011:Q4 period. Employing instrumental variable approach, we obtain the following results. First, lower prices of Voice over IP and mobile reduce the demand for fixed-line telephony. This indicates some demand-side substitution. Second, we find no relationship between Voice over IP and fixed-line prices. Third, there is a positive and significant relationship between mobile and fixed-line prices. Estimated own- and cross-price elasticities are in the inelastic range. Hence, calls to deregulate fixed-line telephony may be too premature

Hybrid force/position control for a 3-DOF 1T2R parallel robot: Implementation, simulations and experiments

"This is an Author's Accepted Manuscript of an article published in Cazalilla, José, Marina Vallés, Ángel Valera, Vicente Mata, and Miguel Díaz-Rodríguez. 2016. Hybrid Force/Position Control for a 3-DOF 1T2R Parallel Robot: Implementation, Simulations and Experiments. Mechanics Based Design of Structures and Machines 44 (1 2). Informa UK Limited: 16 31. doi:10.1080/15397734.2015.1030679, available online at: https://www.tandfonline.com/doi/full/10.1080/15397734.2015.1030679."[EN] A robot interacting with the environment requires that the end effector \hboxposition is tracked and that the forces of contact are kept below certain reference values. For instance, in a rehabilitation session using a robotic device, the contact forces are limited by the allowed strength of the human limbs and their complex-joints. In these cases, a control scheme which considers both position and force control is essential to avoid damage to either the end effector or the object interacting with the robot. This paper therefore develops a real-time force/position control scheme for a three-DOF parallel robot whose end effector holds a DOF one translation (1T) and two rotations (2R). The implemented hybrid force/position control considers, as a reference, the normal force on the mobile platform, which is measured by means of a load cell installed on the platform. The position control is designed to track the orientations of the robot either in joint or task space using a model-based control scheme with identified parameters. Moreover, the force control is based on a PD action. The control scheme is developed through simulations, before being applied to an actual parallel robot. The findings show that with the implemented controller, the actual robot accomplishes the reference values for the normal force on the mobile platform, while at the same time the platform accurately follows the required angular orientation.The authors wish to thank the Plan Nacional de I+D, Comision Interministerial de Ciencia y Tecnologia (FEDER-CICYT) for the partial funding of this study under the projects DPI2011-28507-C02-01 and DPI2013-44227-R. This work was also partially supported by the Fondo Nacional de Ciencia, Tecnologia e Innovacion (FONACIT-Venezuela).Cazalilla, J.; Vallés Miquel, M.; Valera Fernández, Á.; Mata Amela, V.; Díaz-Rodríguez, M. (2016). Hybrid force/position control for a 3-DOF 1T2R parallel robot: Implementation, simulations and experiments. Mechanics Based Design of Structures and Machines. 44(1-2):16-31. https://doi.org/10.1080/15397734.2015.1030679S1631441-2Åström, K. J., & Murray, R. M. (2008). Feedback Systems. doi:10.1515/9781400828739Bellakehal, S., Andreff, N., Mezouar, Y., & Tadjine, M. (2011). Force/position control of parallel robots using exteroceptive pose measurements. Meccanica, 46(1), 195-205. doi:10.1007/s11012-010-9411-zCao, R., Gao, F., Zhang, Y., Pan, D., & Chen, W. (2014). A New Parameter Design Method of a 6-DOF Parallel Motion Simulator for a Given Workspace. Mechanics Based Design of Structures and Machines, 43(1), 1-18. doi:10.1080/15397734.2014.904234Carretero, J. A., Podhorodeski, R. P., Nahon, M. A., & Gosselin, C. M. (1999). Kinematic Analysis and Optimization of a New Three Degree-of-Freedom Spatial Parallel Manipulator. Journal of Mechanical Design, 122(1), 17-24. doi:10.1115/1.533542Clavel, R. (1988). DELTA, a fast robot with parallel geometry.Proceedings of 18th International Symposium on Industrial Robot, Lausanne, April, 91–100.Díaz-Rodríguez, M., Mata, V., Valera, Á., & Page, Á. (2010). A methodology for dynamic parameters identification of 3-DOF parallel robots in terms of relevant parameters. Mechanism and Machine Theory, 45(9), 1337-1356. doi:10.1016/j.mechmachtheory.2010.04.007Diaz-Rodriguez, M., Valera, A., Mata, V., & Valles, M. (2013). Model-Based Control of a 3-DOF Parallel Robot Based on Identified Relevant Parameters. IEEE/ASME Transactions on Mechatronics, 18(6), 1737-1744. doi:10.1109/tmech.2012.2212716Farhat, N., Mata, V., Page, Á., & Valero, F. (2008). Identification of dynamic parameters of a 3-DOF RPS parallel manipulator. Mechanism and Machine Theory, 43(1), 1-17. doi:10.1016/j.mechmachtheory.2006.12.011Garg, A., Vikram, C. S., Gupta, S., Sutar, M. K., Pathak, P. M., Mehta, N. K., … Gupta, V. K. (2014). Design and Development of In Vivo Robot for Biopsy. Mechanics Based Design of Structures and Machines, 42(3), 278-295. doi:10.1080/15397734.2014.898587Gough, V. E., Whitehall, S. G. (1962). Universal tire test machine.Proceedings of 9th International Technical Congress FISITA, pp. 117–135.García de Jalón, J., & Bayo, E. (1994). Kinematic and Dynamic Simulation of Multibody Systems. Mechanical Engineering Series. doi:10.1007/978-1-4612-2600-0Lee, K.-M., & Arjunan, S. (1991). A three-degrees-of-freedom micromotion in-parallel actuated manipulator. IEEE Transactions on Robotics and Automation, 7(5), 634-641. doi:10.1109/70.97875Li, Y., & Xu, Q. (2007). Design and Development of a Medical Parallel Robot for Cardiopulmonary Resuscitation. IEEE/ASME Transactions on Mechatronics, 12(3), 265-273. doi:10.1109/tmech.2007.897257Merlet, J.-P. (2000). Parallel Robots. Solid Mechanics and Its Applications. doi:10.1007/978-94-010-9587-7Pierrot, F., Nabat, V., Company, O., Krut, S., & Poignet, P. (2009). Optimal Design of a 4-DOF Parallel Manipulator: From Academia to Industry. IEEE Transactions on Robotics, 25(2), 213-224. doi:10.1109/tro.2008.2011412Rosillo, N., Valera, A., Benimeli, F., Mata, V., & Valero, F. (2011). Real‐time solving of dynamic problem in industrial robots. Industrial Robot: An International Journal, 38(2), 119-129. doi:10.1108/01439911111106336Steward, D. A. (1965). A platform with 6 degrees of freedom.Proceedings of the Institution of Mechanical Engineers, Part 1, vol. 15, pp. 371–386.Valera, A., Benimeli, F., Solaz, J., De Rosario, H., Robertsson, A., Nilsson, K., … Mellado, M. (2011). A Car-Seat Example of Automated Anthropomorphic Testing of Fabrics Using Force-Controlled Robot Motions. IEEE Transactions on Automation Science and Engineering, 8(2), 280-291. doi:10.1109/tase.2010.2079931Vallés, M., Díaz-Rodríguez, M., Valera, Á., Mata, V., & Page, Á. (2012). Mechatronic Development and Dynamic Control of a 3-DOF Parallel Manipulator. 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Synergids and filiform apparatus in the sexual and apomictic dandelions from section Palustria (Taraxacum, Asteraceae)

An evolutionary trend to reduce “unnecessary costs” associated with the sexual reproduction of their amphimictic ancestors, which may result in greater reproductive success, has been observed among the obligatory apomicts. However, in the case of the female gametophyte, knowledge about this trend in apomicts is not sufficient because most of the ultrastructural studies of the female gametophyte have dealt with amphimictic angiosperms. In this paper, we tested the hypothesis that, in contrast to amphimictic plants, synergids in apomictic embryo sacs do not form a filiform apparatus. We compared the synergid structure in two dandelions from sect. Palustria: the amphimictic diploid Taraxacum tenuifolium and the apomictic tetraploid, male-sterile Taraxacum brandenburgicum. Synergids in both species possessed a filiform apparatus. In T. brandenburgicum, both synergids persisted for a long time without any degeneration, in spite of the presence of an embryo and endosperm. We propose that the persistent synergids in apomicts may play a role in the transport of nutrients to the embryo

Mobile Learning Technology: Assessment of Distribution Options and Recommendations

NPS NRP Project PosterThe transformative Ready Relevant Learning (RRL) effort is transitioning the Navy to a modern, science-of-learning approach. That includes delivering novel training practices and content to the point of need, requiring a true "anytime, anywhere" capability (wireless access) for locations around the world and in CONUS learning centers and schoolhouses. To deliver modern training capability anytime and anywhere, the Navy must be able to support mobile and distributed training. This requires that Sailors have access to both hardware and software that allow them to access training resources outside the classrooms, at the point of need whenever they require it. The study will examine ways to provide Sailors ready access to mobile learning technologies for the delivery of modern training content anytime and anywhere. We will conduct a Business Case Analysis for procuring government-issued devices versus relaxation of policies and determine the cybersecurity safeguards that would allow personal device use. The goal of the study is to identify the best value solution in a form of an effective technology ecosystem with respect to the categories of hardware (laptop, tablet, mobile phone, etc.) and present a roadmap describing how to implement and adopt the best value solution.N1 - Manpower, Personnel, Training & EducationThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Mobile Learning Technology: Assessment of Distribution Options and Recommendations

NPS NRP Executive SummaryThe transformative Ready Relevant Learning (RRL) effort is transitioning the Navy to a modern, science-of-learning approach. That includes delivering novel training practices and content to the point of need, requiring a true "anytime, anywhere" capability (wireless access) for locations around the world and in CONUS learning centers and schoolhouses. To deliver modern training capability anytime and anywhere, the Navy must be able to support mobile and distributed training. This requires that Sailors have access to both hardware and software that allow them to access training resources outside the classrooms, at the point of need whenever they require it. The study will examine ways to provide Sailors ready access to mobile learning technologies for the delivery of modern training content anytime and anywhere. We will conduct a Business Case Analysis for procuring government-issued devices versus relaxation of policies and determine the cybersecurity safeguards that would allow personal device use. The goal of the study is to identify the best value solution in a form of an effective technology ecosystem with respect to the categories of hardware (laptop, tablet, mobile phone, etc.) and present a roadmap describing how to implement and adopt the best value solution.N1 - Manpower, Personnel, Training & EducationThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Passive Exercise Adaptation for Ankle Rehabilitation Based on Learning Control Framework

[EN] Ankle injuries are among the most common injuries in sport and daily life. However, for their recovery, it is important for patients to perform rehabilitation exercises. These exercises are usually done with a therapist's guidance to help strengthen the patient's ankle joint and restore its range of motion. However, in order to share the load with therapists so that they can offer assistance to more patients, and to provide an efficient and safe way for patients to perform ankle rehabilitation exercises, we propose a framework that integrates learning techniques with a 3-PRS parallel robot, acting together as an ankle rehabilitation device. In this paper, we propose to use passive rehabilitation exercises for dorsiflexion/plantar flexion and inversion/eversion ankle movements. The therapist is needed in the first stage to design the exercise with the patient by teaching the robot intuitively through learning from demonstration. We then propose a learning control scheme based on dynamic movement primitives and iterative learning control, which takes the designed exercise trajectory as a demonstration (an input) together with the recorded forces in order to reproduce the exercise with the patient for a number of repetitions defined by the therapist. During the execution, our approach monitors the sensed forces and adapts the trajectory by adding the necessary offsets to the original trajectory to reduce its range without modifying the original trajectory and subsequently reducing the measured forces. After a predefined number of repetitions, the algorithm restores the range gradually, until the patient is able to perform the originally designed exercise. We validate the proposed framework with both real experiments and simulation using a Simulink model of the rehabilitation parallel robot that has been developed in our lab.This work has been partially funded by the FEDER-CICYT project with reference DPI2017-84201-R (Integracion de modelos biomecanicos en el desarrollo y operacion de robots rehabilitadores reconfigurables) financed by Ministerio de Economia, Industria e Innovacion (Spain).Abu-Dakka, FJ.; Valera Fernández, Á.; Escalera, JA.; Abderrahim, M.; Page Del Pozo, AF.; Mata Amela, V. (2020). Passive Exercise Adaptation for Ankle Rehabilitation Based on Learning Control Framework. Sensors. 20(21):1-23. https://doi.org/10.3390/s20216215S123202

Combined Admittance Control With Type II Singularity Evasion for Parallel Robots Using Dynamic Movement Primitives

[EN] This article addresses a new way of generating compliant trajectories for control using movement primitives to allow physical human-robot interaction where parallel robots (PRs) are involved. PRs are suitable for tasks requiring precision and performance because of their robust behavior. However, two fundamental issues must be resolved to ensure safe operation: first, the force exerted on the human must be controlled and limited, and second, Type II singularities should be avoided to keep complete control of the robot. We offer a unified solution under the dynamic movement primitives (DMP) framework to tackle both tasks simultaneously. DMPs are used to get an abstract representation for movement generation and are involved in broad areas, such as imitation learning and movement recognition. For force control, we design an admittance controller intrinsically defined within the DMP structure, and subsequently, the Type II singularity evasion layer is added to the system. Both the admittance controller and the evader exploit the dynamic behavior of the DMP and its properties related to invariance and temporal coupling, and the whole system is deployed in a real PR meant for knee rehabilitation. The results show the capability of the system to perform safe rehabilitation exercises.This work was supported in part by the Fondo Europeo de Desarrollo Regional under Grant PID2021-125694OB-I00, in part by the Vicerrectorado de Investigacion de la Universitat Politecnica de Valencia under Grant PAID-11-21, and in part by the Ministerio de Universidades, Gobierno de Espana under Grant FPU18/05105.Escarabajal-Sánchez, RJ.; Pulloquinga-Zapata, J.; Valera Fernández, Á.; Mata Amela, V.; Vallés Miquel, M.; Castillo-García, FJ. (2023). Combined Admittance Control With Type II Singularity Evasion for Parallel Robots Using Dynamic Movement Primitives. IEEE Transactions on Robotics. 39(3):2224-2239. https://doi.org/10.1109/TRO.2023.32381362224223939

Evaluating the Effectiveness of Blended Learning Strategies in Navy Training

NPS NRP Project PosterThe Navy needs better ways to train, educate, and assess higher-order cognitive skills, applied proficiencies, and teamwork abilities. Currently, the Navy's approaches to Instructional System Design (ISD) do not adequately address the development of personalization and adaptive training techniques integrated into the future learning continuum concept required by Ready Relevant Learning (RRL). Adopting a blended training environment approach, which combines a plethora of learning approaches empowered by the modern technology solutions, web-based delivery, and traditional classroom methods, could offer a balanced solution to developing modernized, efficient, effective, and adaptable training delivery systems with integrated ability to assess training quality and impact on Fleet readiness and on-the-job performance. This study will evaluate the effectiveness of blended training environments against traditional training methods currently used in Navy rating training. The evaluation will use the existing classroom-based curriculum and learning materials in carefully designed reconfigurations that mix web-based interactive content and in-class activities, coupled with an online student evaluation system. Based on the findings, we will present a roadmap on how to implement, adopt and integrate the most efficient training solution that supports the CNO directed acceleration of RRL and provides lessons learned across all Navy formal accession training.N1 - Manpower, Personnel, Training & EducationThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.