855 research outputs found
The structure of three-dimensional sheet cavitation
No full textMechanical Maritime and Materials Engineerin
Observation of a diffraction minimum in the proton-proton elastic scattering at the ISR
No full textWe have investigated the pp elastic scattering at the CERN Intersecting Storage Rings (ISR). We report results for centre-of-mass scattering angles between 30 and 100 mrad and for centre-of-mass energies of 23.5,30.7, 44.9 and 53 GeV. The elastic differential cross-section shows a diffraction-like shape with a sharp minimum at about t = −1.4 GeV2
A surrogate-assisted propeller optimisation in propulsive and regenerative operations: A case study
No full textEngineering has become more and more optimisation and simulation based. This causes an increase in the use of optimisation methods for complex problems. This thesis focuses on the implementation of a surrogate-assisted optimisation method for propeller optimisation, to design a better propeller in a shorter timespan. Therewith reducing both: computational expenses, and fuel consumption when a propeller has been built. This thesis tries to reach two objectives: The first goal is to implement a surrogate-assisted method for propeller optimisation. The other objective is to design a propeller for both propulsive as well as for regenerative operations. To succeed, this thesis has been limited to the testing and coupling of SAMO-COBRA (A Fast Surrogate Assisted Constrained Multi-objective Optimization Algorithm) with PropArt. The testing has been based on benchmark tests where SAMO-COBRA was tested against CMOPSO and NSGA-II (the two algorithms that MARIN currently uses for propeller optimisation). Here, SAMO-COBRA outperformed NSGA-II and CMOPSO on over half of the test cases and is therefore considered for the rest of the research.The thesis evaluates propellers using a Boundary Element Momentum theory, which is a mathematical method that is the basis of MARINs in-house propeller tool PROCAL. To be able to model propellers that operate at high J values correctly certain improvements regarding the wake expansion and alignment have been made. For the wake expansion three methods are proposed. After comparing the open water diagram of a F4-63-0.6 propeller, that is evaluated by PROCAL, and the one that was made after physical testing. It can be concluded that the disk theory is the most versatile implementation for propellers that operate at a range of advance ratio. Results show that from the two proposed methods, the method where the wake pitch is prescribed by the advance ratio results in the best wake alignment. The test case optimises 3 configurations, two separate designs, one for propulsion and one for regeneration. A normal CPP that is loaded under a negative angle of attack for regeneration and a propeller that can be fully reversed for regenerative operations (the propeller is loaded from the trailing edge in regeneration). The propeller is optimised to reach a maximum regenerative power whilst minimising the propulsive power. The optimum propeller has to satisfy multiple constraints based on cavitational-, geometrical- and separation of flow constraints. The optimisation using SAMO-COBRA did not yield feasible results for any of the three cases. After removing the cavitational constraints a new analysis of the results has been done, it is found that a propeller that is rotated 180 degrees can provide the highest regenerative power. This thesis proposes multiple hypotheses that cause the lack of feasible results of the test case. The proposed causes are: errors in the PropArt model, problems in the compiled PropArt version or a too low convergence level of COBYLA.Marine Technolog
Dr. Mostafa Moin, Minister of Science, Research and Technology, Islamic Republic of Iran
No full textL. to. r.:Dr Henrik Foeth, Team Leader, CMS experiment; Dr Daniel Denegri, Physics Coordinator, CMS experiment; Prof. Tejinder Virdee, Deputy Spokesman, CMS experiment; Prof. Luciano Maiani, CERN Director-General (signing); Mr Jean-Marie Dufour, Head of the Legal Service, Mr Ghodratollah Habibpour Gharakol (back); Dr Abdolali Sharghi, Advisor to the Minister and Director General, Office of International Scientific Cooperation, Ministry of Science, Research and Technology; Dr Mostafa Moin, Minister of Science, Research and Technology, Islamic Republic of Iran (signing); Dr Reza Mansouri, Director, International Scientific Meetings Office, Ministry of Science, Research and Technology; H. E. Dr Ali Khorram, Extraordinary and plenipotentiary Ambassador to the United Nations in Geneva and Dr Hans F. Hoffmann, CERN Director for Technology Transfer & for Scientific Computing.
Multiwire proportional chamber spectrometer for the CERN Intersecting Storage Rings
No full textThe design, construction, and performance of a multiwire proportional chamber (MWPC) system ( approximately 10 k wires) constructed for use at the CERN Intersecting Storage Rings (ISR) is described. This system employs hybrid integrated circuitry for pulse detection and storage, and is read out via a CAMAC compatible system. The chambers plus two large-aperture magnets with accompanying scintillation and Cherenkov counters form a versatile multiparticle spectrometer system which has been used to investigate particle systems produced near 0 at the CERN ISR. (11 refs)
A Search for slow massive particles with Z<or=2 at the CERN Intersecting Storage Rings
No full textA large scintillation counter telescope positioned at right angles to the crossing beams at the CERN ISR was used in a search for slow (stopping) massive particles with charges Z<or=2. No events which could be unambiguously identified as being due to unknown particles were seen among 10/sup 8/ charged particles which passed through the telescope. (4 refs)
Proton diffraction dissociation studies at the CERN ISR
No full textProton diffraction dissociation was studied at the ISR with a double-arm magnetic spectrometer close to the forward directions of the two ISR beams. Events with a single charged particle in one spectrometer and a jet in the opposite direction were found to be predominantly diffraction dissociation. In these events a positive correlation was observed between the mass and decay multiplicity of the fireball. The shape of the diffractive mass spectrum and its consistency with triple pomeron coupling were investigated at s = 31 GeV, 45 GeV and 53.4 GeV
Equilibrium adsorption data from breakthrough curves with variable velocity and pressure
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