| 1. |
- Faatz, B., et al.
(author)
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Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator
- 2016
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In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18
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Journal article (peer-reviewed)abstract
- Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.
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| 2. |
- Wunderer, C. B., et al.
(author)
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Detector developments at DESY
- 2016
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In: Journal of Synchrotron Radiation. - 0909-0495 .- 1600-5775. ; 23, s. 111-117
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Journal article (peer-reviewed)abstract
- With the increased brilliance of state-of-the-art synchrotron radiation sources and the advent of free-electron lasers (FELs) enabling revolutionary science with EUV to X-ray photons comes an urgent need for suitable photon imaging detectors. Requirements include high frame rates, very large dynamic range, single-photon sensitivity with low probability of false positives and (multi)-megapixels. At DESY, one ongoing development project-in collaboration with RAL/STFC, Elettra Sincrotrone Trieste, Diamond, and Pohang Accelerator Laboratory-is the CMOS-based soft X-ray imager PERCIVAL. PERCIVAL is a monolithic active-pixel sensor back-thinned to access its primary energy range of 250 eV to 1 keV with target efficiencies above 90%. According to preliminary specifications, the roughly 10 cm × 10 cm, 3.5k × 3.7k monolithic sensor will operate at frame rates up to 120 Hz (commensurate with most FELs) and use multiple gains within 27 μm pixels to measure 1 to ∼ 100000 (500 eV) simultaneously arriving photons. DESY is also leading the development of the AGIPD, a high-speed detector based on hybrid pixel technology intended for use at the European XFEL. This system is being developed in collaboration with PSI, University of Hamburg, and University of Bonn. The AGIPD allows singlepulse imaging at 4.5 MHz frame rate into a 352-frame buffer, with a dynamic range allowing single-photon detection and detection of more than 10000 photons at 12.4 keV in the same image. Modules of 65k pixels each are configured to make up (multi)megapixel cameras. This review describes the AGIPD and the PERCIVAL concepts and systems, including some recent results and a summary of their current status. It also gives a short overview over other FEL-relevant developments where the Photon Science Detector Group at DESY is involved. © 2016 International Union of Crystallography.
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| 3. |
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| 4. |
- Björkenstam, Staffan C, 1981, et al.
(author)
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Enhancing digital human motion planning of assembly tasks through dynamics and optimal control
- 2016
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 44, s. 20-25
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Conference paper (peer-reviewed)abstract
- Better operator ergonomics in assembly plants reduce work related injuries, improve quality, productivity and reduce cost. In this paper we investigate the importance of modeling dynamics when planning for manual assembly operations. We propose modeling the dynamical human motion planning problem using the Discrete Mechanics and Optimal Control (DMOC) method, which makes it possible to optimize with respect to very general objectives. First, two industrial cases are simulated using a quasi-static inverse kinematics solver, demonstrating problems where this approach is sufficient. Then, the DMOC-method is used to solve for optimal trajectories of a lifting operation with dynamics. The resulting trajectories are compared to a steady state solution along the same path, indicating the importance of using dynamics.
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| 5. |
- Bohlin, R., et al.
(author)
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Automatic creation of virtual manikin motions maximizing comfort in manual assembly processes
- 2012
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In: Technologies and Systems for Assembly Quality, Productivity and Customization. - : Conference on Assembly Technologies & Systems (CIRP). - 9780615640228 ; , s. 209-212
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Conference paper (peer-reviewed)abstract
- Effective simulation of manual assembly operations considering ergonomic load and clearance demands requires detailed modeling of human body kinematics and motions, as well as a tight coupling to powerful algorithms for collision-free path planning. The focus in this paper is a unified solution that automatically creates assembly motions for manikins taking kinematic constraints, balance, contact forces, collision avoidance and comfort into account. The manikin used in this work has 162 degrees of freedom - six exterior fictitious joints determine the position of the lower lumbar and the remaining ones are interior joints. The inverse kinematic problem leads to an underdetermined system allowing us to pick a solution that maximizes a scalar valued comfort function. The comfort function offers a generic way to give preference to certain poses while avoiding others, typically by considering joint limits, forces and moments on joints, and magnitude of contact forces. In order to avoid collisions, poses close to collision are penalized. The method is implemented and demonstrated on two challenging assembly operations taken from the automotive industry.
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| 6. |
- Mårdberg, P., et al.
(author)
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Controller Hierarchies for Efficient Virtual Ergonomic Assessments of Manual Assembly Sequences
- 2016
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 44, s. 435-440
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Conference paper (peer-reviewed)abstract
- A novel framework for manikin motion planning has been implemented to reduce the time needed to perform virtual ergonomic assessments of manual assembly sequences. The user feeds high level instructions into a hierarchical controller system. Depending on the state of the manikin and the objects in the environment, the controllers compute a sequence of low level instructions interpreted as path planning instances for the manikin. The result is automatically generated collision-free and ergonomically sound motions that accomplish the assembly tasks. The framework is demonstrated on relevant cases from the industry and the reduction in manual simulation preparation time is proven.
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| 7. |
- Mårdberg, Peter, 1980, et al.
(author)
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Using a Formal High-level Language to Instruct Manikins to Assemble Cables
- 2014
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 23:C, s. 29-34
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Conference paper (peer-reviewed)abstract
- In this paper, a formal high-level language is used to generate simulations where a manikin assembles flexible cables. The language generates assembly instructions for the manikin, which automatically performs the corresponding assembly motion with as good ergonomic as possible. Due to weight, stiffness and narrow regions, it may be difficult to perform an assembly of the cable. Our approach allows us to verify that it may be performed in an ergonomically sound way. The generated instructions are formally verified to ensure that assembly order is held and to prevent erroneous assembly states. The simulations have been made on industrial test cases.
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