Perceptual simplification for model-based binaural room auralisation

Design of computationally efficient yet perceptually realistic room auralisation algorithms require a careful selection of the early reflections to be auralised. A perception-based simplification algorithm is presented for the selection of the early reflections using a criterion which depends both on the arrival time and on the angle of incidence of the early reflection with respect to the listener. Results of two subjective tests for the evaluation of the proposed algorithm are presented. The proposed algorithm is shown to provide a significant reduction in the number of early reflections without significantly affecting the tested localisational or spatial qualities of auralisation.     

Physical model for the width distribution of axons

The distribution of widths of axons was recently investigated, and was found to have a distinct peak at an optimized value. The optimized axon width at the peak may arise from the conflicting demands of minimizing energy consumption and assuring signal transmission reliability. The distribution around this optimized value is found to have a distinct non-Gaussian shape, with an exponential “tail”. We propose here a mechanical model whereby this distribution arises from the interplay between the elastic energy of the membrane surrounding the axon core, the osmotic pressure induced by the neurofilaments inside the axon bulk, and active processes that remodel the microtubules and neurofilaments inside the axon. The axon’s radius of curvature can be determined by the cell’s control of the osmotic pressure difference across the membrane, the membrane tension or by changing the composition of the different components of the membrane. We find that the osmotic pressure, determined by the neurofilaments, seems to be the dominant control parameter.     

Nanosecond pulse laser melting investigation by IR radiometry and reflection-based methods

Experimental system for nanosecond laser melting investigation was developed containing three independent noncontact methods: infrared radiometry, time-resolved reflectivity of He-Ne laser and sample surface reflected KrF heating laser pulse. The system was applied to the investigation of laser melting of Cu, Mo, Ni, Si, Sn, Ti, steel ?SN 15330 and stainless steel ?SN 17246 samples. For metallic samples the IR radiometry signal was transformed to temperature. Obtained surface temperature and reflectivity spectra in nanosecond time scale (10-1000 ns) for wide range of energy densities (100-5500 mJ cm⁻²) are presented. Interesting evolutions were found. Melting thresholds and melting durations were determined from the measured curves. The applicability of the methods is evaluated.     

Development of a Fourier-Transform Ion-Cyclotron-Resonance detection for short-lived radionuclides at SHIPTRAP

The Penning-trap mass spectrometer SHIPTRAP at GSI is designed to provide clean and cooled beams of singly charged radioactive ions produced in fusion-evaporation reactions and separated in-flight by the velocity filter SHIP. The scientific goals include mass spectrometry, atomic and nuclear spectroscopy, and chemistry of transuranium species which are not available at ISOL- or fragmentation facilities Penning-trap based mass measurements on radionuclides relies up to now on the destructive time-of-flight ion-cyclotron-resonance method. One of the main limitations to the experimental investigations is the low production rate of most of these exotic nuclides, for which the use of this detection scheme is not applicable. A sensitive and non-destructive method, like the narrow-band Fourier Transform ion-cyclotron-resonance technique, is ideally suited for the identification and characterization of these species. A new cryogenic trap setup for SHIPTRAP exploiting this detection technique as well as some results of first preparatory tests are presented.     

Synthesis,Characterization of 9, 9＇-Bianthracene and Fabrication of 9, 9＇-Bianthracene Field-Effect Transistors

We synthesize and purify 9, 9＇-bianthracene with the purity up to 96.4%. The electronic and crystallographic structures of 9, 9＇-bianthracene are studied. The results of a joint experimental investigation based on a combination of x-ray diffraction （XRD） spectra, hydrogen nuclear magnetic （HNMR） spectra, infrared absorption （FT-IR） spectra, and mass spectra （MS） of 9, 9＇-bianthracene are obtained. The uniform compact film is observed by an atomic-force microscope （AFM）. Organic field effect transistors （OFETs） with an active layer based on the synthesized 9, 9＇-bianthracene are fabricated for the first time. Its field-effect mobility is as large as 0.067 cm^2 /（V·s） and the on/off ratio is above 5 ×10^4. The result demonstrates that the oligomerization of a small semiconductor molecule is an effective method to develop high-mobility organic semiconductors.     

Long silicon nitride nanowires synthesized in a simple route

Long silicon nitride (Si₃N₄) nanowires with high purity were synthesized by heating mixtures of SiO₂ powders and short carbon fibers at 1430°C for 2 h in a flowing N₂ atmosphere. The nanowires had the length of 1–2 millimeters and the diameters of 70–300 nm, and were mainly composed of ⍺-Si₃N₄, growing along the [001] direction. The vapor–solid (VS) mechanism was employed to interpret the nanowires growth.     

Digital positron lifetime spectroscopy at EPOS

As the digital equipment to measure positron lifetimes gets cheaper and more widely used, it is decided that EPOS, the ELBE positron source will sample the signals from the photomultipliers directly and evaluate it online or offline by digital means.Still using isotope sources, the EPOS lifetime spectrometer results in a timing resolution of around 170 ps (with ⁶⁰Co), which compares good to analog equipment. A distinct improvement is expected when a coincidence setup will be used at ELBE. However, also the software needs further improvement: while one of the goals is of course to achieve the best time resolution, there is also the aspect of runtime and expandability. Results of evaluations will be presented and compared with results from other groups.     

Construction and timing system of the EPOS beam system

The Forschungszentrum Dresden-Rossendorf provides an intense pulsed 40 MeV electron beam with high brilliance and low emittance (ELBE). The pulse has a length of 1-10 ps and a repetition time of 77 ns, or in slow mode 616 ns. The EPOS system (ELBE Positron Source) generates by pair production on a tungsten converter and a tungsten moderator an intense pulsed beam of mono-energetic positrons. To transport the positrons to the laboratory (12 m) we constructed a magnetic beam guidance system with a longitudinal magnetic field of 75 G. In the laboratory outside the cave, the positron beam is chopped and bunched according to the time structure, because the very sharp bunch structure of the electron pulses is broadened for the positron beam due to transport and moderation.     

Emissivity measurements of opaque gray bodies up to 2000 °C by a dual-frequency pyrometer

In the framework of the SPES project at LNL-INFN a method for emissivity measurements by a double-frequency pyrometer in the infrared region at high temperatures on opaque gray bodies of SiC and graphite is presented. The measurement method proposed in this work reveals a good fitting with literature values. Moreover, the effect of surface finishing on emissivity values has been investigated.     

Blue emission of ZrO2:Tm nanocrystals with different crystal structure under UV excitation

In this paper, thulium doped ZrO₂ nanocrystals with different phases were prepared by Pechini sol-gel complex method. The effects of host structure, phases and concentration on luminescence properties of Tm³⁺ ions were investigated. With the increase of the concentration of Tm³⁺ ions, the phosphors phase transformed from monoclinic to tetragonal structure and all the phosphors emitted blue light. However, because the environment symmetry around Tm³⁺ in m-ZrO₂ (C_2h) is worse than that of t-ZrO₂ (D_4h), there were still obvious differences in the emission and excitation. The reason was investigated with the help of energy level diagram. In addition, the quenching concentration of Tm³⁺ in ZrO₂ host is 1 m/m%.