Arbeiten der Hamburgischen Schiffbau-Versuchsanstalt in Hamburg

Ohne Zusammenfassung VDI     

Advanced Biometric Pen System for Recording and Analyzing Handwriting

Handwriting dynamics which reflect fine motor skills of writers can be recorded with pen based writing systems. They are generally equipped with a diversity of sensors, such as pen tip pressure and tilt-acceleration sensors mounted inside the pen or pen tip x-y position sensors integrated on a specific graphic tablet. Such writing systems are essentially applied for biometric personal identification or handwriting recognition. In this paper, an advanced biometric pen based system for capturing and analyzing handwriting dynamics of a person is presented. Features of the device as well as evaluation of its sensor data are discussed. The system actually comprises a standard WACOM graphic tablet where its input pen is equipped additionally with a sensor to measure the grip pressure of fingers holding the pen. By combining x-y position data of the tablet and grip pressure data of the pen an improvement of performance in handwriting and person recognition is achieved. The experimental results have shown that among the single sensors, the grip sensor data gives best recognition accuracy and improves the recognition rates of handwritten PINs or persons by about 1%, when fused with x-y position data. It shows excellent accuracy in handwriting recognition and depicts detailed information about fine motor skill which is primarily because of data sampled by the finger grip pressure sensor. The enhanced input device has great promise not only for biometrics but also for biomedical applications.     

Measures of subproblem criticality in decomposition algorithms for shop scheduling

Work centre-based decomposition approaches, especially variants of the Shifting Bottleneck algorithm, have been very successful in solving job-shop-scheduling problems. These methods decompose the problem into subproblems involving a single work centre (usually a single machine), which they solve sequentially. We propose new measures of subproblem criticality and show via computational experiments that several of these provide solutions comparable in quality with those obtained from previous work in substantially less central processing unit time.     

“三明治”零件机械连接技术的开发

 “三明治”零件的主要优点是重量轻、刚性好，它特别适用于大型、高强度结构，但是在机械工程应用中几乎只用于次要场合，这主要是由于缺少可广泛应用的连接技术。介绍了研究工作中包括所有基本方案的系统论述和从系统工程设计角度对它进行评价。     

Turbulent opposed-jet flames: A critical benchmark experiment for combustion LES

Turbulent opposed-jet configurations have gained attention as a challenging test case to validate the mixing and combustion models used in the simulation of turbulent combustion. In general, validation requires comprehensive experimental information on flow and scalar fields, and the emergence of combustion large-eddy simulation (CLES) necessitated more advanced diagnostics. These laser-optical techniques allow measurements not only of single-point statistics but of structural information of the flame, such as correlations, gradients, and structure functions. This paper presents thorough experimental and numerical investigations of one isothermal and two reacting turbulent opposed jets with fuel jets consisting of partially premixed methane. Its focus is on one configuration at and one configuration close to the highest possible Reynolds numbers where flames could be stabilized. The experimental data presented comprise information on axial velocity, main species concentrations, temperature, mixture fraction, scalar dissipation rate, joint probability density functions, and structure functions. These quantities are compared to results of highly resolved CLES to show the configuration's suitability as a critical benchmark for state-of-the art combustion LES.     

Pharmacological inactivation of the endothelin type A receptor in the early chick embryo: a model of mispatterning of the branchial arch derivatives

In the present study, we have applied an antagonist treatment to the chick embryo in ovo in order to demonstrate and dissect the essential roles of the endothelin type A (ETA) receptor in the embryonic development. We have cloned, sequenced and expressed the cDNA of the chick ETA receptor and shown that its affinity for endothelin antagonists is very similar to that shown by its mammalian counterparts. We have studied the spatio-temporal expression pattern of this receptor by in situ hybridization and shown that there is a high level of its mRNA within the mesenchyme of the branchial arches at E3-E5, in keeping with the direct effect of endothelin-1 (ET-1) on the fate of this region of the embryo. Unlike the endothelin type B (ETB) receptor mRNA, ETA mRNA is not expressed in neural crest cells during emigration from the neural tube, but is detected in neural crest-derived ectomesenchyme of the branchial arches. Finally, the functional involvement of this receptor in craniofacial and cardiovascular organogenesis was assessed by selectively inactivating the ETA receptor with specific antagonists applied during the time period corresponding to the expression of the ETA receptor and colonisation of the branchial arches. Embryos treated by these antagonists show a severe reduction and dysmorphogenesis of the hypobranchial skeleton, as well as heart and aortic arch derivative defects. This phenotype is very similar to that obtained in mice by gene inactivations of ET-1 and ETA. These results are observed with ETA antagonists but not with an ETB antagonist, and are dependent on the dose of the antagonists used and on the time of application to the embryo. Altogether, these data strongly show that the ET-1/ETA pathway, in chicken as in mammals, is a major factor involved directly and functionally in morphogenesis of the face and heart. This experimental model of pharmacological inactivation of a gene product described in this study offers a simple and rapid alternative to gene inactivation in mouse. This strategy can be applied to other ligand-receptor systems and extended to compounds of various chemical and functional natures.     

Origin of inhomogeneity in spark plasma sintered bismuth antimony telluride thermoelectric nanocomposites

Anisotropy and inhomogeneity are ubiquitous in spark plasma sintered thermoelectric devices. However, the origin of inhomogeneity in thermoelectric nanocomposites has rarely been investigated so far. Herein, we systematically study the impact of inhomogeneity in spark plasma sintered bismuth antimony telluride (BiSbTe) thermoelectric nanocomposites fabricated from solution-synthesized nanoplates. The figure of merit can reach 1.18, which, however, can be overestimated to 1.88 without considering the inhomogeneity. Our study reveals that the inhomogeneity in thermoelectric properties is attributed to the non-uniformity of porosity, textures and elemental distribution from electron backscatter diffraction and energy-dispersive spectroscopy characterizations. This finding suggests that the optimization of bulk material homogeneity should also be actively pursued in any future thermoelectric material research.

     

Special Issue on Multimedia Network Protocols and Enabling Radio Technologies ‐ Call for Papers

Call for Papers

Special Issue on Multimedia Network Protocols and Enabling Radio Technologies Call for Papers     

A comparison of indentations of different size and geometry in single-quasicrystalline AIPdMn

The study compares impressions into one and the same single-quasicrystalline Al₇₀Pd₂₀Mn₁₀ sample (surface of fivefold symmetry) that were performed by spherical and pointed indenters (Vickers- and corner-of-a-cube-geometry) and investigated using Atomic Force Microscopy (AFM). The Meyer hardness number was found to vary with indentation size in a manner similar to materials that work harden, though this behavior must have a different physical origin: for spherical indentations the hardness number slightly increases with increasing load (Meyer hardness evolution), whereas for pyramid-shaped indenters a considerable hardness increase in case of decreasing load can be stated. Spherical indentations show little piling-up only in contrast to pointed indentations where huge elevations surrounding the indent developed. Different degrees of lateral cracking can account for this observation. In case of Vickers indentations the material breaks into segments which display mutual shearing. Distinct differences can also be noticed with respect to the volume balance between the apparent piled-up volume around the impression and the volume of the displaced material. This balance proves positive for pyramidal and negative for spherical impressions.