Sonochemistry: Scope, Limitations… and Artifacts

Heterogeneous sonochemistry, generally described as the most useful aspect of sonochemistry, suffers from the difficulty of defining the experimental conditions for the reference (silent) reaction. Clearly the use of an efficient agitation system for the silent reaction strongly reduces the value of the so-called sonochemical effect, which becomes in some cases, less than 1 (anti-sonochemical effect!).The 'cleaning' effect of ultrasound is extremely efficient to expel micro-crystals from the surface of an electrode which is simultaneously an immersion ultrasonic horn. By sending out-of-phase electric pulses and acoustic pulses, new nano materials (metals, alloys, semiconductors, oxides) are easily prepared in high purity

Purpose and effect of performance evaluations. How to avoid risks and wrong developments

In "Nach-PISA-Deutschland" werden viele neue, z.T. modifizierte Verfahren der Leistungsbeurteilung gefordert oder bereits durchgeführt. Dabei kommt "der Definition von Beurteilungszwecken eine wichtige Steuerungsfunktion" zu. Der Autor unterscheidet vier "Zweckkategorien": 1. Leistungsbeurteilung zur "Förderung von Lehr-/Lernvorgängen", 2. als "Grundlage für Kompetenzzertifikate", 3. als Hilfe bei Laufbahnentscheidungen oder 4. als Grundlage für "Qualitätssicherung und Bildungsplanung". (DIPF/Orig./Un).In "post-PISA Germany", many new or modified procedures of performance evaluations are either demanded or already carried out. However, the respective purposes are in need of clarification. In addition, one will have to accept that such evaluations do not only serve to support individual learning processes. They also imply new tasks arise for school administration and teaching staff. (DIPF/Orig.

Objektivierung von Herzgeräuschen beim Rind mittels Phonokardiographie

The objective of the present study was to examine if heart murmurs in adult cattle can be objectively diagnosed using phonocardiography. The examinations were conducted using phonocardiograms (PCG) and required a scheme for evaluation. Twenty cattle older than two years of age that were hospitalised at the Clinic for Ruminants, Oberschleissheim, were used for the study. In all of them, heart murmurs were detected during auscultation. The Meditron Analyzer 4.0 (Welch Allyn GmbH & Co KG, Jungingen) allowed the simultaneous recording of electrocardiogram (ECG) and PCG. The ECG using a thoracic lead served as a timeline for the PCG. In a pre-test (n = 20) so called threshold values were established which marked the division between the “background noise” (amplitudes between the heart sounds) and murmurs. These threshold values (for positive and negative range) were established for four different locations per side of the body (in the third and fourth intercostals spaces (ICS), dorsally and ventrally, re-spectively), as well as for the presentation of the PCG with use of a 50, 100 Hz filter, respectively. In the subsequent main study twenty animals were examined clinically and according to the results of auscultation assigned to the heart murmur grades (HM) 0-6 and categorised into groups: HM “faint” (HM grade 0-2), HM “moderately loud” (HM grade 3-4) and HM “loud” (HM grade 5-6). PCG were recorded on all eight locations mentioned above. The quality and number of acceptable PCGs of the right body side was very low, thus these recordings were not used in the analysis. For the PCG evaluation certain selected heart actions were presented in a larger scale and printed on graph paper. Systole and diastole were marked using the ECG and the threshold values were drawn in manually. In addition, systole and diastole were divided into 10 and 20 equal intervals for the 50 Hz and 100 Hz presentations, respectively. At these determined points the amplitudes were measured and recorded if they were above/below the threshold values or if no values could be measured at these points. For amplitudes that were outside the threshold values relative frequency at each point of measurement for each location and for 50 and 100 Hz presentations was calculated. Comparing the sum of the amplitudes outside the threshold values between the groups “faint” and “loud” significant differences were found for the location 1 (third ICS, dorsally, left side) in the systole at 50 Hz and for the loca-tion 2 (third ICS, ventrally, left side) in the systole at 100 Hz (p = 0.041 and p = 0.034). A significant difference between the groups “faint” and “loud” was found for the loca-tion 1 in the systole at 50 Hz (p = 0.042) concerning the area under the curve using the amplitudes measured at these 10 and 20 points of measurement, respectively. In addition, the mean values of the amplitudes that were outside the threshold values were calculated. Comparing the groups “faint” and “loud” a significant difference was also found for the location 1 in the systole at 50 Hz in the positive range (p = 0.034) as well as for location 2 in the systole at 50 Hz in the negative range (p = 0.045). Further investigations could confirm the tendencies found in the present study. Additional investigations with a larger number of animals could help to classify heart murmurs. Besides, they might help to increase the chances of obtaining usable measurements from the right side. Also, an algorithm for automatic evaluation of PCGs based on the data of the present study would be very helpful

Helicopter Flight Test of 3-D Imaging Flash LIDAR Technology for Safe, Autonomous, and Precise Planetary Landing

Two flash lidars, integrated from a number of cutting-edge components from industry and NASA, are lab characterized and flight tested for determination of maximum operational range under the Autonomous Landing and Hazard Avoidance Technology (ALHAT) project (in its fourth development and field test cycle) which is seeking to develop a guidance, navigation, and control (GN&C) and sensing system based on lidar technology capable of enabling safe, precise crewed or robotic landings in challenging terrain on planetary bodies under any ambient lighting conditions. The flash lidars incorporate pioneering 3-D imaging cameras based on Indium-Gallium-Arsenide Avalanche Photo Diode (InGaAs APD) and novel micro-electronic technology for a 128 x 128 pixel array operating at 30 Hz, high pulse-energy 1.06 micrometer Nd:YAG lasers, and high performance transmitter and receiver fixed and zoom optics. The two flash lidars are characterized on the NASA-Langley Research Center (LaRC) Sensor Test Range, integrated with other portions of the ALHAT GN&C system from partner organizations into an instrument pod at NASA-JPL, integrated onto an Erickson Aircrane Helicopter at NASA-Dryden, and flight tested at the Edwards AFB Rogers dry lakebed over a field of human-made geometric hazards during the summer of 2010. Results show that the maximum operational range goal of 1 km is met and exceeded up to a value of 1.2 km. In addition, calibrated 3-D images of several hazards are acquired in real-time for later reconstruction into Digital Elevation Maps (DEM's)

GIFTS SM EDU Data Processing and Algorithms

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) Sensor Module (SM) Engineering Demonstration Unit (EDU) is a high resolution spectral imager designed to measure infrared (IR) radiances using a Fourier transform spectrometer (FTS). The GIFTS instrument employs three Focal Plane Arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The raw interferogram measurements are radiometrically and spectrally calibrated to produce radiance spectra, which are further processed to obtain atmospheric profiles via retrieval algorithms. This paper describes the processing algorithms involved in the calibration stage. The calibration procedures can be subdivided into three stages. In the pre-calibration stage, a phase correction algorithm is applied to the decimated and filtered complex interferogram. The resulting imaginary part of the spectrum contains only the noise component of the uncorrected spectrum. Additional random noise reduction can be accomplished by applying a spectral smoothing routine to the phase-corrected blackbody reference spectra. In the radiometric calibration stage, we first compute the spectral responsivity based on the previous results, from which, the calibrated ambient blackbody (ABB), hot blackbody (HBB), and scene spectra can be obtained. During the post-processing stage, we estimate the noise equivalent spectral radiance (NESR) from the calibrated ABB and HBB spectra. We then implement a correction scheme that compensates for the effect of fore-optics offsets. Finally, for off-axis pixels, the FPA off-axis effects correction is performed. To estimate the performance of the entire FPA, we developed an efficient method of generating pixel performance assessments. In addition, a random pixel selection scheme is designed based on the pixel performance evaluation

Microstructuring of Steel and Hard Metal using Femtosecond Laser Pulses

AbstractNew results on three-dimensional micro-structuring of tungsten carbide hard metal and steel using femtosecond laser pulses will be presented. For the investigations, a largely automated high-precision fs-laser micromachining station was used. The fs-laser beam is focused onto the sample surface using different objectives. The investigations of the ablation behaviour of the various materials in dependence of the laser processing parameters will be presented. In the second part, complex 3D microstructures with a variety of geometries and resolutions down to a few micrometers will be presented. On of the Goal of these investigations was to create defined microstructures in tooling equipments such as cutting inserts

GIFTS SM EDU Radiometric and Spectral Calibrations

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) Sensor Module (SM) Engineering Demonstration Unit (EDU) is a high resolution spectral imager designed to measure infrared (IR) radiance using a Fourier transform spectrometer (FTS). The GIFTS instrument gathers measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The raw interferogram measurements are radiometrically and spectrally calibrated to produce radiance spectra, which are further processed to obtain atmospheric profiles via retrieval algorithms. This paper describes the processing algorithms involved in the calibration. The calibration procedures can be subdivided into three categories: the pre-calibration stage, the calibration stage, and finally, the post-calibration stage. Detailed derivations for each stage are presented in this paper

A Super-Resolution Algorithm for Enhancement of FLASH LIDAR data

A novel method for enhancement of the spatial resolution of 3-dimensional Flash Lidar images is being proposed for generation of elevation maps of terrain from a moving platform. NASA recognizes the Flash LIDAR technology as an important tool for enabling safe and precision landing in future unmanned and crewed lunar and planetary missions. The ability of the Flash LIDAR to generate 3-dimensional maps of the landing site area during the final stages of the descent phase for detection of hazardous terrain features such as craters, rocks, and steep slopes is under study in the frame of the Autonomous Landing and Hazard Avoidance (ALHAT) project. Since single frames of existing FLASH LIDAR systems are not sufficient to build a map of entire landing site with acceptable spatial resolution and precision, a super-resolution approach utilizing multiple frames has been developed to overcome the instrument s limitations. Performance of the super-resolution algorithm has been analyzed through a series of simulation runs obtained from a high fidelity Flash LIDAR model and a high resolution synthetic lunar elevation map. For each simulation run, a sequence of FLASH LIDAR frames are recorded and processed as the spacecraft descends toward the landing site. Simulations runs having different trajectory profiles and varying LIDAR look angles of the terrain are also analyzed. The results show that adequate levels of accuracy and precision are achieved for detecting hazardous terrain features and identifying safe areas of the landing site

Effect of process parameters on the energy requirement in ultrasonical treatment of waste sludge

Mechanical treatment methods are used as pre-treatment methods in order to enhance the efficiency of conventional sludge treatment processes and the sludge becomes more suitable for its complete treatment. The ultrasound is an alternative method among other methods, but because of its high energy requirement it should be optimized before utilization. This work gives the optimized parameters such as sonication time, sonication power (these parameters are the two factors which play part for energy calculations), type of sludge, cooling requirements and solid content in the sludge solution. Even if the previous researchers prefer to use the energy (specific energy usually), we have found out that both the sonication time and the sonication power have individual importance. For municipal sludge the main conclusion can be summarized as: “high power-short retention time” is more effective than “low power-long retention time”. As this phenomenon may alter from sludge to sludge, various combinations of power and retention time should be tried while keeping the volume small and the concentration below a certain level. The process should be performed at moderate temperatures and the efficiency increases if the sludge is as homogeneous as possible