Short range radio research in Twente

The research and education by the Telecommunication Engineering Group at the University of Twente is dedicated to physical layer topics in communications. Three research tracks have prominence: Short Range Radio, Microwave Photonics, and Electromagnetic Compatibility. Arjan is active in the Short Range Radio division, and will briefly outline the interests and activities of this group. Furthermore he will present some results of the research that he did during his short sabbatical in Belfast last year. This concerns the performance analysis of a frequency offset modulation scheme using wideband noise carriers. The main advantage of such a scheme is that it enables fast receiver synchronization without channel adaptation, while providing robustness to multipath fading and in-band interference. This is important for low-power wireless systems with bursty traffic, such as sensor networks. In the talk a semi-analytical framework for evaluating its bit error rate performance in wideband frequency-selective fading channels will be described. Some numerical results will be presented, based on channel models developed in the IEEE 802.15.4a channel modeling subgroup. These illustrate that the considered system can be designed with a lower fading margin than a narrowband system

The irradiated ISM of ULIRGs

The nuclei of ULIRGs harbor massive young stars, an accreting central black hole, or both. Results are presented for molecular gas that is exposed to X-rays (1-100 keV, XDRs) and far-ultraviolet radiation (6-13.6 eV, PDRs). Attention is paid to species like HCO+, HCN, HNC, OH, H2O and CO. Line ratios of HCN/HCO+ and HNC/HCN discriminate between PDRs and XDRs. Very high J (>10) CO lines, observable with HIFI/Herschel, discriminate very well between XDRs and PDRs. In XDRs, it is easy to produce large abundances of warm (T>100 K) H2O and OH. In PDRs, only OH is produced similarly well.Comment: 5 pages, 6 figures, to appear in: IAU Symposium 242 Astrophysical Masers and their Environment

Molecular properties of (U)LIRGs: CO, HCN, HNC and HCO+

The observed molecular properties of a sample of FIR-luminous and OH megamaser (OH-MM) galaxies have been investigated. The ratio of high and low-density tracer lines is found to be determined by the progression of the star formation in the system. The HCO+/HCN and HCO+/HNC line ratios are good proxies for the density of the gas, and PDR and XDR sources can be distinguished using the HNC/HCN line ratio. The properties of the OH-MM sources in the sample can be explained by PDR chemistry in gas with densities higher than 10^5.5 cm^-3, confirming the classical OH-MM model of IR pumped amplification with (variable) low gains.Comment: 5 pages, 2 figures, to appear in: IAU Symposium 242 Astrophysical Masers and their Environment

If services aren't delivered, people won't pay: the role of measurement problems and monitoring in Payments for Environmental Services

The idea of Payments for environmental services (PES) has an appealing simplicity, which may explain the success of the concept. However, successful projects are far limited though and two constraints have been identified in literature. The first is limited demand: too few service users are so confident about the mechanism that they are willing to pay. The second obstacle is poor knowledge on the institutional requirements entailing incentive and livelihood mechanisms which so far have received comparatively less attention. This paper focuses on both constraints by arguing that monitoring effectiveness and conditionality of PES schemes are crucial and that institutional arrangements for monitoring should be in place. By analysing in a systematic way what types of measurement problems there are, the paper shows that the type of monitoring that is required within a PES has consequences for the institutional arrangement needed for a successful PES. We find that the institutional arrangements for monitoring vary according to (i) the type of environmental service and its underlying production process, (ii) the extent to which the environmental service can be freely observed or measured, (iii) the extent to which activities of the resource managers who provide the environmental service can be freely observed, and finally (iv) the deterministic or stochastic nature of production processes.PES, monitoring, measurement, institutional arrangement, Environmental Economics and Policy,

A Distributed Routing Algorithm for Internet-wide Geocast

Geocast is the concept of sending data packets to nodes in a specified geographical area instead of nodes with a specific address. To route geocast messages to their destination we need a geographic routing algorithm that can route packets efficiently to the devices inside the destination area. Our goal is to design an algorithm that can deliver shortest path tree like forwarding while relying purely on distributed data without central knowledge. In this paper, we present two algorithms for geographic routing. One based purely on distance vector data, and one more complicated algorithm based on path data. In our evaluation, we show that our purely distance vector based algorithm can come close to shortest path tree performance when a small number of routers are present in the destination area. We also show that our path based algorithm can come close to the performance of a shortest path tree in almost all geocast situations

Innovations in risk insurance models

Smallholder farmers face a range of risks related to production, transactions and human resources which often impact on their farming operations as well as their livelihoods. Farm output may vary from season to season because of the vagaries of the weather, especially in countries where agriculture is predominantly rain-fed. Crop production can also be affected by diseases, pests and other natural factors. They face human resource risks associated with death, disease and disability affecting the farmer and his/her family members. They may incur losses as a result of inability to enforce contracts and may themselves be vulnerable to legal risks arising from farm legislations or regulatory standards. Smallholder farmers are also exposed to uncertain access to markets and high price risks which may sometimes occur, or are accentuated by inefficiencies in markets or policy interventions. This policy brief provides an overview of different insurance tools that can be used by farmers to manage risks

Locating the information: applications, technologies and future aspects

In today’s world, the demand for information is growing rapidly with respect to the human curiosity to explore the inside and the outside of our planet. In a simple analogy, the human body has thousands of sensors called receptor neurons to obtain information such as temperature or pressure from the environment. Similarly, recent developments in electronics and wireless communications lead engineers to the design of small-sized, low-power, low-cost sensor nodes which have the ability to communicate with each other over short distances and collect the information that is gathered