30,257 research outputs found
Анализ современных систем САПР с целью их использования для моделирования работы бурильной колонны в скважине
Nowadays, the assembly of laser systems is dominated by manual operations, involving elaborate alignment by means of adjustable mountings. From a competition perspective, the most challenging problem in laser source manufacturing is price pressure, a result of cost competition exerted mainly from Asia. From an economical point of view, an automated assembly of laser systems defines a better approach to produce more reliable units at lower cost. However, the step from todays manual solutions towards an automated assembly requires parallel developments regarding product design, automation equipment and assembly processes. This paper introduces briefly the idea of self-optimizing technical systems as a new approach towards highly flexible automation. Technically, the work focuses on the precision assembly of laser resonators, which is one of the final and most crucial assembly steps in terms of beam quality and laser power. The paper presents a new design approach for mini aturized laser systems and new automation concepts for a robot-based precision assembly, as well as passive and active alignment methods, which are based on a self-optimizing approach. Very promising results have already been achieved, considerably reducing the duration and complexity of the laser resonator assembly. These results as well as future development perspectives are discussed
Understanding and optimising the packing density of perylene bisimide layers on CVD-grown graphene
The non-covalent functionalisation of graphene is an attractive strategy to
alter the surface chemistry of graphene without damaging its superior
electrical and mechanical properties. Using the facile method of aqueous-phase
functionalisation on large-scale CVD-grown graphene, we investigated the
formation of different packing densities in self-assembled monolayers (SAMs) of
perylene bisimide derivatives and related this to the amount of substrate
contamination. We were able to directly observe wet-chemically deposited SAMs
in scanning tunnelling microscopy (STM) on transferred CVD graphene and
revealed that the densely packed perylene ad-layers adsorb with the conjugated
{\pi}-system of the core perpendicular to the graphene substrate. This
elucidation of the non-covalent functionalisation of graphene has major
implications on controlling its surface chemistry and opens new pathways for
adaptable functionalisation in ambient conditions and on the large scale.Comment: 27 pages (including SI), 10 figure
Chain of refined perception in self-optimizing assembly of micro-optical systems
Today, the assembly of laser systems requires a large share of manual
operations due to its complexity regarding the optimal alignment of optics.
Although the feasibility of automated alignment of laser optics has been
shown in research labs, the development effort for the automation of
assembly does not meet economic requirements – especially for low-volume
laser production. This paper presents a model-based and sensor-integrated
assembly execution approach for flexible assembly cells consisting of a
macro-positioner covering a large workspace and a compact micromanipulator
with camera attached to the positioner. In order to make full use of
available models from computer-aided design (CAD) and optical simulation, sensor systems at different
levels of accuracy are used for matching perceived information with model
data. This approach is named "chain of refined perception", and it allows for
automated planning of complex assembly tasks along all major phases of
assembly such as collision-free path planning, part feeding, and active and
passive alignment. The focus of the paper is put on the in-process
image-based metrology and information extraction used for identifying and
calibrating local coordinate systems as well as the exploitation of that
information for a part feeding process for micro-optics. Results will be
presented regarding the processes of automated calibration of the robot
camera as well as the local coordinate systems of part feeding area and
robot base
Dimensionality and design of isotropic interactions that stabilize honeycomb, square, simple cubic, and diamond lattices
We use inverse methods of statistical mechanics and computer simulations to
investigate whether an isotropic interaction designed to stabilize a given
two-dimensional (2D) lattice will also favor an analogous three-dimensional
(3D) structure, and vice versa. Specifically, we determine the 3D ordered
lattices favored by isotropic potentials optimized to exhibit stable 2D
honeycomb (or square) periodic structures, as well as the 2D ordered structures
favored by isotropic interactions designed to stabilize 3D diamond (or simple
cubic) lattices. We find a remarkable `transferability' of isotropic potentials
designed to stabilize analogous morphologies in 2D and 3D, irrespective of the
exact interaction form, and we discuss the basis of this cross-dimensional
behavior. Our results suggest that the discovery of interactions that drive
assembly into certain 3D periodic structures of interest can be assisted by
less computationally intensive optimizations targeting the analogous 2D
lattices.Comment: 22 pages (preprint version; includes supplementary information), 5
figures, 3 table
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One-step volumetric additive manufacturing of complex polymer structures.
Two limitations of additive manufacturing methods that arise from layer-based fabrication are slow speed and geometric constraints (which include poor surface quality). Both limitations are overcome in the work reported here, introducing a new volumetric additive fabrication paradigm that produces photopolymer structures with complex nonperiodic three-dimensional geometries on a time scale of seconds. We implement this approach using holographic patterning of light fields, demonstrate the fabrication of a variety of structures, and study the properties of the light patterns and photosensitive resins required for this fabrication approach. The results indicate that low-absorbing resins containing ~0.1% photoinitiator, illuminated at modest powers (~10 to 100 mW), may be successfully used to build full structures in ~1 to 10 s
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