44 research outputs found
Rapid, Brushless Self-assembly of a PS-b-PDMS Block Copolymer for Nanolithography
AbstractBlock copolymers (BCP) are highly promising self-assembling precursors for scalable nanolithography. Very regular BCP nanopatterns can be used as on-chip etch masks. The first step in the processing of BCP thin films is usually the chemical modification of the substrate surface, typically by grafting of a brush layer that renders the surface energy neutral relative to the constituent blocks. We provide here a first study on rapid, low temperature self-assembly of PS-b-PDMS (polystyrene-block-polydimethylsiloxane) on silicon substrates without a brush layer. We show that it forms line and antidot patterns after short solvo-thermal annealing. Unlike previous reports on this system, low temperature and short annealing time provide self-assembly in homogeneous thin films covering large substrate areas. This on-chip mask was then used for pattern transfer to the underlying silicon substrate. SEM (scanning electron microscope) images reveal silicon nanowires relative to the PDMS patterns of the BCP mask
Anomalous impact of thermal fluctuations on spintransfer torque induced ferrimagnetic switching
The dynamics of a spin torque driven ferrimagnetic (FiM) system is
investigated using the two-sublattice macrospin model. We demonstrate an
ultrafast switching in the picosecond range. However, we find that the
excessive current leads to the magnetic oscillation. Therefore, faster
switching cannot be achieved by unlimitedly increasing the current. By
systematically studying the impact of thermal fluctuations, we find the
dynamics of FiMs can also be distinguished into the precessional region, the
thermally activated region, and the cross-over region. However, in the
precessional region, there is a significant deviation between FiM and
ferromagnet (FM), i.e., the FM is insensitive to thermal fluctuations since its
switching is only determined by the amount of net charge. In contrast, we find
that the thermal effect is pronounced even a very short current pulse is
applied to the FiM. We attribute this anomalous effect to the complex relation
between the anisotropy and overdrive current. By controlling the magnetic
anisotropy, we demonstrate that the FiM can also be configured to be
insensitive to thermal fluctuations. This controllable thermal property makes
the FiM promising in many emerging applications such as the implementation of
tunable activation functions in the neuromorphic computing.Comment: 27 pages, 8 figure
Good Computational Practice in the Assignment of Absolute Configurations by TDDFT Calculations of ECD Spectra
Quantum-mechanical calculations of chiroptical properties have rapidly become the most popular method for assigning absolute configurations (AC) of organic compounds, including natural products. Black-box time-dependent Density Functional Theory (TDDFT) calculations of electronic circular dichroism (ECD) spectra are nowadays readily accessible to nonexperts. However, an uncritical attitude may easily deliver a wrong answer. We present to the Chirality Forum a discussion on what can be called good computational practice in running TDDFT ECD calculations, highlighting the most crucial points with several examples from the recent literature
Evaluating Optimum Levels Of Detail For 3d Interactive Aviation Maintenance Instructions
With the aviation industry shifting from paper based maintenance instructions to digital maintenance instructions, there needs to be a standard for what goes into creating the digital instructions. This study was done to determine what the optimum level of detail for 3D interactive aviation maintenance instructions. The definition of optimum for this study was: lowest amount of geometrical data with lowest rendering needed for comprehension and ease of use
Supporting UAVs with Edge Computing: A Review of Opportunities and Challenges
Over the last years, Unmanned Aerial Vehicles (UAVs) have seen significant
advancements in sensor capabilities and computational abilities, allowing for
efficient autonomous navigation and visual tracking applications. However, the
demand for computationally complex tasks has increased faster than advances in
battery technology. This opens up possibilities for improvements using edge
computing. In edge computing, edge servers can achieve lower latency responses
compared to traditional cloud servers through strategic geographic deployments.
Furthermore, these servers can maintain superior computational performance
compared to UAVs, as they are not limited by battery constraints. Combining
these technologies by aiding UAVs with edge servers, research finds measurable
improvements in task completion speed, energy efficiency, and reliability
across multiple applications and industries. This systematic literature review
aims to analyze the current state of research and collect, select, and extract
the key areas where UAV activities can be supported and improved through edge
computing
System-Level Thermal-Aware Design of 3D Multiprocessors with Inter-Tier Liquid Cooling
Rising chip temperatures and aggravated thermal reliability issues have characterized the emergence of 3D multiprocessor system-on-chips (3D-MPSoCs), necessitating the development of advanced cooling technologies. Microchannel based inter-tier liquid cooling of ICs has been envisaged as the most promising solution to this problem. A system-level thermal-aware design of electronic systems becomes imperative with the advent of these new cooling technologies, in order to preserve the reliable functioning of these ICs and effective management of the rising energy budgets of high-performance computing systems. This paper reviews the recent advances in the area of systemlevel thermal modeling and management techniques for 3D multiprocessors with advanced liquid cooling. These concepts are combined to present a vision of a green data center of the future which reduces the CO2 emissions by reusing the heat it generates