大型公共运输中的热塑性组合框架结构的设计、制造和分析

薄壁复合材料具有优越的性能，包括高强度、轻质、抗弯、抗剪性强等，因而经常用于大型交通领域。从目前的研究来看，已经设计、分析并制造出一种用于大型运输卡车的薄壁复合热塑组合结构来代替传统的金属结构。考虑了三种横截面构造，分别是矩形、V字形、C形，对比了编织方向在（0／90）6，[±45／（0／90）2]，及[±45／（0／90）]3等不同的复合材料层合结构。该结构选用碳纤／聚亚苯硫化物（carbon／PPS）作为原材料，采用单模复合成型。通过面内冲压试验，验证了碳／PPS组合结构有限元分析结果，论证了薄壁碳／PPS热组合结构制造策略的设计理念。     

Application of the Msplit method for filtering airborne laser scanning data-sets to estimate digital terrain models

ALS point cloud filtering involves the separation of observations representing the physical terrain surface from those representing terrain details. A digital terrain model (DTM) is created from a subset of points representing the ground surface. The accuracy of the generated DTM is influenced by several factors, including the survey method used, the accuracy of the source data, the applied DTM generation algorithm, and the survey conditions.

This article proposes the use of a new estimation method in the filtering of point clouds obtained from airborne laser scanning (ALS), provisionally called M_split-estimation. The application of M_split-estimation in ALS data filtering requires the determination of the appropriate functional model for the surface, which will be used in the filtering of the set of points. A polynomial terrain surface model was selected for this purpose. Two methods of filtering using the M_split method are presented. The first is based on the estimated parameters of the polynomial describing the surface (called the ‘quality’ approach in the article). The second method (provisionally called the ‘quantity’ method) is carried out in two stages. The first stage is point cloud filtering, which results in two subsets being created. One of these is the subset of points intended for DTM creation, while the other contains the remaining points. The second stage of the approach is the creation of a DTM from the first subset.

Since the M_split method has an analytical character, the ATIN method was selected to verify the correct operation of the method. The ATIN method is based on computational geometry and uses repeated Delaunay triangulation and statistical evaluation of the geometric parameters. Comparison of M_split with a method based on different principles mitigates errors arising from similarly functioning methods belonging to the same group of filters. The choice of the ATIN method was also dictated by its established position among filtering algorithms. The method is well-known, documented, and verified and this ensures that filtering by this method provides a reliable result that can serve as a reference for comparison with the proposed new filtering method.

The theoretical discussion presented in this article was verified with two practical examples. The results obtained from computation by the M_split method with appropriate terrain models encourage more detailed theoretical and empirical tests of this method for the filtering and segmentation of ALS data-sets.     

Content driven QoE assessment for video frame rate and frame resolution reduction

Video bit rate reduction is very important for all video streaming applications. One possibility involves quantization domain and the majority of the work devoted to bit rate reduction focuses on this aspect only. The other possibility is to modify a video in time or space domain i.e. change the frames per second FPS rate or frame resolution FR. In this paper we present two no reference metrics mapping FPS rate and FR into MOS (Mean Opinion Scale). The performance of both models is significantly improved by incorporating content characteristics such as spatial information SI and temporal information TI. The impact on Quality of Experience (QoE) of both content characteristics is discussed with relation to the FPS rate and FR changes and general conclusions are drawn. The models were estimated and verified upon results of subjective experiments performed using video sequences of diverse spatial and temporal variability. The considered FPS rate was changed from 5 to 30 and the considered FR was changed from SQCIF to SD.     

Manganese-Labeled Alginate Hydrogels for Image-Guided Cell Transplantation

Cell transplantation has been studied extensively as a therapeutic strategy for neurological disorders. However, to date, its effectiveness remains unsatisfactory due to low precision and efficacy of cell delivery; poor survival of transplanted cells; and inadequate monitoring of their fate in vivo. Fortunately, different bio-scaffolds have been proposed as cell carriers to improve the accuracy of cell delivery, survival, differentiation, and controlled release of embedded stem cells. The goal of our study was to establish hydrogel scaffolds suitable for stem cell delivery that also allow non-invasive magnetic resonance imaging (MRI). We focused on alginate-based hydrogels due to their natural origin, biocompatibility, resemblance to the extracellular matrix, and easy manipulation of gelation processes. We optimized the properties of alginate-based hydrogels, turning them into suitable carriers for transplanted cells. Human adipose-derived stem cells embedded in these hydrogels survived for at least 14 days in vitro. Alginate-based hydrogels were also modified successfully to allow their injectability via a needle. Finally, supplementing alginate hydrogels with Mn ions or Mn nanoparticles allowed for their visualization in vivo using manganese-enhanced MRI. We demonstrated that modified alginate-based hydrogels can support therapeutic cells as MRI-detectable matrices.     

Beitrag zur Thermodynamik der Kieselsäurereduktion

Beschreibung von Laboratoriumsversuchen zur Reduktion flüssiger Schlacken des Systems CaO–MgO–SiO₂–Al₂O₃ mit Gehalten von 28,5 bis 38,5% SiO₂ im Graphittiegel in Gegenwart von kohlenstoffgesättigtem Eisen bei 1600 °C. Ermittlung der Gleichgewichtsverteilungskonstante des Siliciums zwischen kohlenstoffgesättigten Eisenschmelzen und kieselsäurehaltigen Schlacken bei unbewegter Schmelze. Aussagen über die Aktivität der Kieselsäure in der Schlacke des Systems CaO–MgO–SiO₂–Al₂O₃.     

LIQUID PHASE SINTERED METAL MATRIX COMPOSITE MATERIALS

Iron-base and aluminum-base composite materials reinforced with various ceramic particulates have been fabricated via powder metallurgy and liquid phase sintering. The advantage of this manufacturing route is that conventional powder metallurgy processing equipment can be used to fabricate metal matrix/ceramic composites. Furthermore, this approach makes it possible to manufacture these composites to near-net-shape. A number of matrix/ceramic combinations have been examined: Fe-C-Si and Fe-Cu with ZrO₂ additions and a Al-Cu-Si-Mg alloy with SiC or Al₂O₃ additions. The interfacial structures were characterized and found to play a significant role in controlling the properties of the composites. Reinforcement was observed in several systems. However, a glassy interfacial layer forms when Si additions and oxide reinforcements are present; the resultant particle/matrix bond strength is weak and reinforcement.     

Stereological Macropore Analysis of a Controlled Pore Glass by use of Small-Angle Scattering

A first measurement (1) of the isotropic Small-Angle Scattering intensity I(h) of a defined controlled mesoporous glass before and a second measurement (2) after alkaline removing of the mesoporous colloidal silica in the macropores of the main silica framework were performed. Consequently, (1) considered a mesoporous glass (MePG) and (2) considered the immediately-afterwards-outcoming macroporous glass (MaPG).The SAS correlation functions and the chord-length distribution densities of the macropores were determined in both cases (so-called filled (1) empty (2) macropores). There exist no differences between outer size and shape and geometrical arrangement of filled/empty macropores at all. Certainly, as a consequence of the missing filling of the macropores in the MaPG-case, the scattering intensities are changed by a constant factor for small h-values and absolutely different for large h-values. The geometric arrangement of the macropores, distances 20 nm < r < 150 nm, involves a high symmetry in the corresponding MePG and MaPG type glass. There exists a relatively restricted placing of the pore axis and the pore positions in space.     

Thermal stability of the nickel-base superalloy B-1900 + Hf with tantalum variations

The microstructure of the solutionized and aged nickel-base superalloy B-1900 + Hf was examined after additional aging at 982 °C for 72, 250, and 1000 hours. Alloy compositions that were examined contained the normal 1.34 at. pct (4.3 wt pct). Ta as well as 0.67 at. pct and zero Ta levels. The γ phase agglomerated, became plate-like in morphology, and decreased in volume fraction for all three alloys throughout the aging treatments. Changes which occurred in the γ and γ' phase compositions were nearly complete after 72 hours of aging while changes in the MC carbide composition continued throughout the aging. Blocky M₆C carbides precipitated along the grain boundaries of all three alloys in the first 72 hours of aging. In addition, an acicular form of this Mo/Cr/Ni-rich carbide developed in the intragranular regions of the Ta-containing alloys. Formerly an Undergraduate Student, Department of Metallurgical Engineering, Michigan Technological University.