In-Situ Measurements of Load Partitioning in a Metastable Austenitic Stainless Steel: Neutron and Magnetomechanical Measurements

In order to construct physically based models of the mechanical response of metastable austenitic steels, one must know the load partitioning between the austenite and the strain-induced martensitic phases. While diffraction-based techniques have become common for such measurements, they often require access to large facilities. In this work, we have explored a simple magnetic technique capable of providing a measure of the stresses in an embedded ferromagnetic phase. This technique makes use of the coupling between the elastic strain and the magnetic response of the $\alpha^{\prime}$ -martensite in an austenitic stainless steel undergoing straining. The magnetic technique proposed here is compared to neutron diffraction measurements made on the same material and is shown to give nearly identical results. The resulting predictions of the load partitioning to the $\alpha^{\prime}$ -martensite phase suggest that $\alpha^{\prime}$ deforms in a complex fashion, reflecting the fact that the microstructure is progressively transformed from austenite to martensite with straining. In particular, it is shown that the apparent hardening of the $\alpha^{\prime}$ -martensite suggests elastic deformation as an important source of high macroscopic work-hardening rate in this material.     

I-V and low frequency noise characterization of poly and amorphous silicon Ti- and Co-salicide resistors

Accurate characterization of polysilicon resistors can help in the design and the fabrication of deep-sub-micron CMOS technologies. In this paper we have studied poly and amorphous silicon Ti- and Co-salicide resistors. In order to discriminate between contact and bulk material contribution transmission line model (TLM) test structures are well adapted for both current-voltage (I-V) and low frequency noise (LFN) characterization. Measurements are undertaken as a function of the geometry (inter-electrode length and electrode width) and of the bias current.From I-V measurements sheet resistance of the different bulk materials (poly or amorphous silicon) and contact resistances of the two different processes (TiSi₂ or CoSi₂) are extracted.Experimentally noise voltage spectral density is measured and converted in resistance spectral density. Noise spectra were always fitted with a 1/f component and white noise. Then, like for I-V characterization (i.e. analyzing the noise of different sample lengths), the contact and bulk 1/f noise contribution is extracted. When contact noise is found to be negligible, bulk material noise is directly modelled according to Hooge relation; otherwise we can only estimate the bulk material. Then the normalised α parameter is used to compare material quality.     

State of the Art in Dense Monocular Non-Rigid 3D Reconstruction

3D reconstruction of deformable (or non-rigid) scenes from a set of monocular 2D image observations is a long-standing and actively researched area of computer vision and graphics. It is an ill-posed inverse problem, since—without additional prior assumptions—it permits infinitely many solutions leading to accurate projection to the input 2D images. Non-rigid reconstruction is a foundational building block for downstream applications like robotics, AR/VR, or visual content creation. The key advantage of using monocular cameras is their omnipresence and availability to the end users as well as their ease of use compared to more sophisticated camera set-ups such as stereo or multi-view systems. This survey focuses on state-of-the-art methods for dense non-rigid 3D reconstruction of various deformable objects and composite scenes from monocular videos or sets of monocular views. It reviews the fundamentals of 3D reconstruction and deformation modeling from 2D image observations. We then start from general methods—that handle arbitrary scenes and make only a few prior assumptions—and proceed towards techniques making stronger assumptions about the observed objects and types of deformations (e.g. human faces, bodies, hands, and animals). A significant part of this STAR is also devoted to classification and a high-level comparison of the methods, as well as an overview of the datasets for training and evaluation of the discussed techniques. We conclude by discussing open challenges in the field and the social aspects associated with the usage of the reviewed methods.     

Synthesis and Characterization of High-Entropy CrMoNbTaVW Thin Films Using High-Throughput Methods

High-entropy alloys (HEAs) or complex concentrated alloys (CCAs) offer a huge research area for new material compositions and potential applications. Since the combination of several elements sometimes leads to unexpected and unpredictable material properties. In addition to the element combinations, the optimization of the element proportions in CCAs and HEAs is also a decisive factor in tailoring desired material properties. However, it is almost impossible to achieve the composition and characterization of CCAs and HEAs with a sufficient number of compositions by conventional experiments. Therefore, an optimized high-throughput magnetron sputtering synthesis to fabricate a new HEA gradient layer of six elements is presented. With this approach, the compositional space of the HEA system CrMoNbTaVW can be studied in different subsections to determine the influence of the individual elements and their combinations on the structure, morphology, and physical properties (hardness and resistivity). It is found that the Cr-, Ta-, and W-rich phases, which have a grain size of 10–11 nm, exhibit the hardest mechanical properties, whereas V-, Ta-, and Cr-rich compounds exhibit the highest electrical resistivity. The combination of high-throughput synthesis, automated analysis tools, and automated data interpretation enables rapid and time-efficient characterization of the novel CrMoNbTaVW gradient film.     

Assessment of Mechanical and Optical Properties of Al 6060 Alloy Particles by Removal of Contaminants

The use of aluminum as a light-weight construction material in automotive engineering has increased steadily in recent years among other sectors. However, the production of primary aluminum requires significantly more energy than the production of steel, which motivates the recycling of existing aluminum components. Based on the results of past investigations, this interdisciplinary study expands the potential applications of a friction-induced solid-state recycling process to reduce the amount of energy, which is needed in the aluminum production and thus also to reduce the CO₂ footprint of the industrial sector. To increase the processability of different conditions of the aluminum chips, a chemical pretreatment was performed to remove an applied cooling lubricant. This study shows that under the use of the chemical cleaning method presented here, it is possible to improve the mechanical properties significantly.     

Revisiting flow-based load balancing: Stateless path selection in data center networks

Hash-based load-balancing techniques are widely used to distribute the load over multiple forwarding paths and preserve the packet sequence of transport-level flows. Forcing a long-lived, i.e., elephant, flow to follow a specific path in the network is a desired mechanism in data center networks to avoid crossing hot spots. This limits the formation of bottlenecks and so improves the network use. Unfortunately, current per-flow load-balancing methods do not allow sources to deterministically force a specific path for a flow.In this paper, we propose a deterministic approach enabling end hosts to steer their flows over any desired load-balanced path without relying on any packet header extension. By using an invertible mechanism instead of solely relying on a hash function in routers, our method allows to easily select the packet’s header field values in order to force the selection of a given load-balanced path without storing any state in routers.We perform various simulations and experiments to evaluate the performance and prove the feasibility of our method using a Linux kernel implementation. Furthermore, we demonstrate with simulations and lab experiments how MultiPath TCP can benefit from the combination of our solution with a flow scheduling system that efficiently distributes elephant flows in large data center networks.