Towards a Traffic Measuring System Utilizing Tire Pressure Monitoring Systems (TPMS)

The number of wireless devices influencing everyday life communication behaviour increases continuously. This trend encourages traffic engineers to develop systems which utilize the identifier of wireless communication standards to measure traffic. The principle to derive traffic parameters by querying the device’s address via the Bluetooth® interface is well known and frequently tested by the ITS community. Additionally, the DLR develops methods for measuring travel times in a road network on the basis of Wi-Fi. A new field of DLR’s research is to detect and recognize vehicles via wireless networks integrated in modern automobiles. Tire pressure monitoring systems (TPMS) are thought to be promising in-vehicle sensor systems for purposes of traffic. They evaluate inflation pressure of tires and transmit the measured data along with its static identifier to an electronic control unit (ECU) wirelessly. After being mandatory in the U.S., in the European Union all vehicles type approved after November 1st, 2012 have to be equipped with TPMS as well as all vehicles manufactured after November 1st, 2014. Thus, the dissemination level of motor vehicles coming with TPMS will theoretically increase up to 100 percent within the upcoming years. Since it is mandatory for every sold run-flat tire system, already today car dealers sell vehicle equipped with TPMS. For proof of concept the authors selected an aftermarket TPMS consisting of four sensors and display unit. Its sensors were easy to mount by replacing the valve caps with the sensor caps. The sensors proved to be advantageous for our purposes since by removing and reinstating the battery, a measurement and transmission can be triggered. Thus the moment of transmission was known, the raw signal data is easy to capture. Since the protocols do not rely on cryptographic mechanisms, the modulation scheme was determined: the data transmission of the selected TPMS utilizes an amplitude shift keying in the 433 MHz band. Next, we resolved the encoding scheme. The sensors employed Manchester encoding, which is a binary signalling mechanism that combines data and clock into bit-symbols. In order to understand the message’s bitfield, we varied pressure and temperature and observed which bits changed

Mass distributions of star clusters for different star formation histories in a galaxy cluster environment

Clusters of galaxies usually contain rich populations of globular clusters (GCs). We investigate how different star formation histories (SFHs) shape the final mass distribution of star clusters. We assume that every star cluster population forms during a formation epoch of length dt at a constant star-formation rate (SFR). The mass distribution of such a population is described by the embedded cluster mass function (ECMF), which is a pure power law extending to an upper limit M_max. Since the SFR determines M_max, the ECMF implicitly depends on the SFR. Starting with different SFHs, each SFH is divided into formation epochs of length dt at different SFRs. The requested mass function arises from the superposition of the star clusters of all formation epochs. An improved optimal sampling technique is introduced that allows generating number and mass distributions, both of which accurately agree with the ECMF. Moreover, for each SFH the distribution function of all involved SFRs, F(SFR), is computed. For monotonically decreasing SFHs, F(SFR) always follows a power law. With F(SFR), we develope the theory of the integrated galactic embedded cluster mass function (IGECMF). It describes the distribution function of birth stellar masses of star clusters that accumulated over a formation episode much longer than dt. The IGECMF indeed reproduces the mass distribution of star clusters created according to the superposition principle. Interestingly, all considered SFHs lead to a turn-down with increasing star cluster mass in their respective IGECMFs. In the past, a turn-down at the high-mass end has been observed for GC systems in different galaxy clusters and in the cluster initial mass function. This behavior can be explained naturally if the observed star cluster ensembles are superpositions of several individual star cluster populations that formed at different times at different SFRs.Comment: Accepted for publication in A&

Tuning the critical solution temperature of polymers by copolymerization

We study statistical copolymerization effects on the upper critical solution temperature (CST) of generic homopolymers by means of coarse-grained Langevin dynamics computer simulations and mean-field theory. Our systematic investigation reveals that the CST can change monotonically or non-monotonically with copolymerization, as observed in experimental studies, depending on the degree of non-additivity of the monomer (A-B) cross-interactions. The simulation findings are confirmed and qualitatively explained by a combination of a two-component Flory-de Gennes model for polymer collapse and a simple thermodynamic expansion approach. Our findings provide some rationale behind the effects of copolymerization and may be helpful for tuning CST behavior of polymers in soft material design.Comment: 8 pages, 6 figure

Monte Carlo event generator validation and tuning for the LHC

We summarise the motivation for, and the status of, the tools developed by CEDAR/MCnet for validating and tuning Monte Carlo event generators for the LHC against data from previous colliders. We then present selected preliminary results from studies of event shapes and hadronisation observables from e+e- colliders, and of minimum bias and underlying event observables from the Tevatron, and comment on the approach needed with early LHC data to best exploit the potential for new physics discoveries at the LHC in the next few years.Comment: Prepared for Proceedings of XII Advanced Computing and Analysis Techniques in Physics Research, November 3-7 2008, Erice, Ital

Small scale assessment of copepod epibionts with the Lightframe On-sight Keyspecies Investigation system (LOKI) in the Norwegian Sognefjord

During an expedition with RV Heincke in October/November 2014 twelve stations in the Norwegian Sognefjord were sampled with the Lightframe On-sight Keyspecies Investigation system (LOKI, Schulz et al. 2010). This optical sampling device allows merging of high quality in-situ image data of individual specimens with ambient environmental parameters on scales of a few centimetres. Investigating raw data for species distribution patterns it became obvious, that epibiont carrying copepods are related to specific water properties in the trough and behind the sill at the entrance of the fjord. Here we give a first peek about small scale relationships between hydrography and interactions of biota, insufficiently detectable with classical net samplings

New developments in event generator tuning techniques

Data analyses in hadron collider physics depend on background simulations performed by Monte Carlo (MC) event generators. However, calculational limitations and non-perturbative effects require approximate models with adjustable parameters. In fact, we need to simultaneously tune many phenomenological parameters in a high-dimensional parameter-space in order to make the MC generator predictions fit the data. It is desirable to achieve this goal without spending too much time or computing resources iterating parameter settings and comparing the same set of plots over and over again. We present extensions and improvements to the MC tuning system, Professor, which addresses the aforementioned problems by constructing a fast analytic model of a MC generator which can then be easily fitted to data. Using this procedure it is for the first time possible to get a robust estimate of the uncertainty of generator tunings. Furthermore, we can use these uncertainty estimates to study the effect of new (pseudo-) data on the quality of tunings and therefore decide if a measurement is worthwhile in the prospect of generator tuning. The potential of the Professor method outside the MC tuning area is presented as well.Comment: To appear in the proceedings of the 13th International Workshop on Advanced Computing and Analysis Techniques in Physics Research, ACAT2010, Jaipur, India, February 22-27, 201