The performance of the quantum adiabatic algorithm on random instances of two optimization problems on regular hypergraphs

In this paper we study the performance of the quantum adiabatic algorithm on random instances of two combinatorial optimization problems, 3-regular 3-XORSAT and 3-regular Max-Cut. The cost functions associated with these two clause-based optimization problems are similar as they are both defined on 3-regular hypergraphs. For 3-regular 3-XORSAT the clauses contain three variables and for 3-regular Max-Cut the clauses contain two variables. The quantum adiabatic algorithms we study for these two problems use interpolating Hamiltonians which are stoquastic and therefore amenable to sign-problem free quantum Monte Carlo and quantum cavity methods. Using these techniques we find that the quantum adiabatic algorithm fails to solve either of these problems efficiently, although for different reasons.Comment: 20 pages, 15 figure

Semiconductor manufacturing simulation design and analysis with limited data

This paper discusses simulation design and analysis for Silicon Carbide (SiC) manufacturing operations management at New York Power Electronics Manufacturing Consortium (PEMC) facility. Prior work has addressed the development of manufacturing system simulation as the decision support to solve the strategic equipment portfolio selection problem for the SiC fab design [1]. As we move into the phase of collecting data from the equipment purchased for the PEMC facility, we discuss how to redesign our manufacturing simulations and analyze their outputs to overcome the challenges that naturally arise in the presence of limited fab data. We conclude with insights on how an approach aimed to reflect learning from data can enable our discrete-event stochastic simulation to accurately estimate the performance measures for SiC manufacturing at the PEMC facility

Technology-Mediated Learning for Resilience

Resilience is a topic of steadily increasing interest. It particularly gains importance when discussing how communities (e.g. municipalities) can prepare themselves for potential future disruptions. A resilient community will overcome immediate shocks, such as an earthquake, as well as stresses, such as the successive outbreak of a pandemic. Due to the novelty of the topic, research particularly exists on theoretical aspects of resilience. Targeting learning - and thereby the local population - is a rather new emergence. To effectively reach, involve, and engage citizens, technology can play a key role. Based on four actual cases from communities we analyse the impact technology has on learning about resilience. We then scrutinize the effectiveness and propose future steps. Thereby, we seek to provide practical advice to local governments and to enrich the theory at the same time

Phase Correlations in Cosmic Microwave Background Temperature Maps

We study the statistical properties of spherical harmonic modes of temperature maps of the cosmic microwave background. Unlike other studies, which focus mainly on properties of the amplitudes of these modes, we look instead at their phases. In particular, we present a simple measure of phase correlation that can be diagnostic of departures from the standard assumption that primordial density fluctuations constitute a statistically homogeneous and isotropic Gaussian random field, which should possess phases that are uniformly random on the unit circle. The method we discuss checks for the uniformity of the distribution of phase angles using a non-parametric descriptor based on the use order statistics, which is known as Kuiper's statistic. The particular advantage of the method we present is that, when coupled to the judicious use of Monte Carlo simulations, it can deliver very interesting results from small data samples. In particular, it is useful for studying the properties of spherical harmonics at low l for which there are only small number of independent values of m and which therefore furnish only a small number of phases for analysis. We apply the method to the COBE-DMR and WMAP sky maps, and find departures from uniformity in both. In the case of WMAP, our results probably reflect Galactic contamination or the known variation of signal-to-noise across the sky rather than primordial non-Gaussianity.Comment: 18 pages, 4 figures, accepted for publication in MNRA

Cosmological parameters from SDSS and WMAP

We measure cosmological parameters using the three-dimensional power spectrum P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in combination with WMAP and other data. Our results are consistent with a ``vanilla'' flat adiabatic Lambda-CDM model without tilt (n=1), running tilt, tensor modes or massive neutrinos. Adding SDSS information more than halves the WMAP-only error bars on some parameters, tightening 1 sigma constraints on the Hubble parameter from h~0.74+0.18-0.07 to h~0.70+0.04-0.03, on the matter density from Omega_m~0.25+/-0.10 to Omega_m~0.30+/-0.04 (1 sigma) and on neutrino masses from <11 eV to <0.6 eV (95%). SDSS helps even more when dropping prior assumptions about curvature, neutrinos, tensor modes and the equation of state. Our results are in substantial agreement with the joint analysis of WMAP and the 2dF Galaxy Redshift Survey, which is an impressive consistency check with independent redshift survey data and analysis techniques. In this paper, we place particular emphasis on clarifying the physical origin of the constraints, i.e., what we do and do not know when using different data sets and prior assumptions. For instance, dropping the assumption that space is perfectly flat, the WMAP-only constraint on the measured age of the Universe tightens from t0~16.3+2.3-1.8 Gyr to t0~14.1+1.0-0.9 Gyr by adding SDSS and SN Ia data. Including tensors, running tilt, neutrino mass and equation of state in the list of free parameters, many constraints are still quite weak, but future cosmological measurements from SDSS and other sources should allow these to be substantially tightened.Comment: Minor revisions to match accepted PRD version. SDSS data and ppt figures available at http://www.hep.upenn.edu/~max/sdsspars.htm

An Integrated Dynamic Analysis Method for Simulating Installation of a Single Blade for Wind Turbines

Installation of blades for wind turbines is challenging due to large lifting height and high precision. Assessment of blade dynamic responses during installation needs advanced simulation tools which are limited at present. This paper aims at developing an integrated simulation tool SIMO-Aero for single blade installation for both onshore and offshore wind turbines. Based on the cross-flow principle, the aerodynamic model is established by accounting for the effect of wind turbulence and dynamic stall. Then it is coupled with SIMO to achieve the integrated simulation tool SIMO-Aero which can account for blade aerodynamics, vessel hydrodynamics and system mechanical couplings. The aerodynamic code is verified by code-to-code comparisons with HAWC2. Furthermore, SIMO-Aero is applied in case studies on the wind-induced dynamic responses of a DTU 10 MW blade during installation using a jack-up crane vessel which is assumed to be rigid, including the crane, and rigidly fixed to the seabed. The characteristics of system dynamic responses prior to mating the blade onto the hub are studied. It is shown that the blade motions are dominated by the pendulum motion. Critical parameters of the installation process are identified. The extreme responses of critical parameters are further studied under turbulent winds and wind gusts.acceptedVersion© 2018. This is the authors’ accepted and refereed manuscript to the article. Locked until 23.2.2020 due to copyright restrictions. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0

Numerical study on the feasibility of offshore single blade installation by floating crane vessels

Compared with jack-up crane vessels that are now widely used in offshore wind turbine installation, floating crane vessels are more flexible with respect to working water depth and are much faster in relocation. They are thus a promising alternative to install offshore wind turbine components, especially in intermediate and deep water. However, the wave-induced motions of the floating vessels make the operations challenging. This study deals with a preliminary feasibility study on offshore single blade installation using floating crane vessels. Two typical floating crane vessels are considered, i.e., a mono-hull vessel and a semi-submersible vessel. They are assumed to be equipped with dynamic positioning systems that can well mitigate the slowly varying horizontal motions. Their overall performance during the blade installation is numerically evaluated by comparing their performance against a typical jack-up crane vessel. The crane dynamics plays a less important role for blade installation by floating vessels, compared to the jack-up crane vessel. The floating vessels’ wave-induced motion greatly affects the blade motion. The semi-submersible vessel causes a much smaller blade motion than the mono-hull vessel. The results indicate that it is feasible to install offshore wind turbine blades by using floating crane vessels provided that the vessel type is properly selected. From the operability point of view, semi-submersible vessels are more feasible than mono-hull vessels for offshore single blade installations.acceptedVersion© 2018. This is the authors’ accepted and refereed manuscript to the article. Locked until 29.12.2020 due to copyright restrictions. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0

Dynamic response analysis of a catamaran installation vessel during the positioning of a wind turbine assembly onto a spar foundation

Installation of floating wind turbines is a challenging task. The time and costs are closely related to the installation method chosen. This paper investigates the performance of an efficient installation concept – a catamaran wind turbine installation vessel. The vessel carries pre-assembled wind turbine units including towers and rotor nacelle assemblies. Each unit is placed onto a pre-installed offshore support structure (in this paper a spar floater) during installation. The challenge is to analyse the responses of the multibody system (catamaran-spar-wind turbine) under simultaneous wind and wave loads. Time-domain simulations were conducted for the coupled catamaran-spar system with mechanical coupling, passive mooring system for the spar, and dynamic positioning control for the catamaran. We focus on the steady-state stage prior to the mating process between one turbine unit and the spar, and discuss the effects of wind loads and wave conditions on motion responses of the catamaran and the spar, relative motions at the mating point, gripper forces and mooring forces. The relative motion at the mating point is less sensitive to the blade orientation, but influenced by the wave conditions. Under the investigated sea states, the present installation method shows decent performance.acceptedVersio

Numerical Modelling and Analysis of the Dynamic Motion Response of an Offshore Wind Turbine Blade during Installation by a Jack-Up Crane Vessel

Jack-up crane vessels are commonly used to install offshore wind turbine blades and other components. A jack-up crane vessel is subjected to wind and wave loads, which cause motion at crane tip. Excessive motion at crane tip can lead to failure of lifting operations. Therefore, the crane tip motion should be properly assessed for jack-up crane vessels. In this study, a fully coupled model is developed for a typical elevated jack-up crane vessel, considering the hydrodynamic and aerodynamic loads on the vessel, the soil-structure interaction, and the structural flexibility of the jack-up legs and crane. The vessel model developed is further coupled with the SIMO-Aero code to achieve a fully coupled aero-hydro-soil-elastic-mechanical code SIMO-RIFLEX-Aero for numerical modeling and dynamic analysis of offshore single blade installation using jack-up crane vessels. The SIMO-RIFLEX-Aero code is then applied to study the dynamic response of the DTU 10 MW wind turbine blade installed by a typical jack-up crane vessel under various wind and wave conditions. The results show that significant motion is induced at crane tip, mainly due to wave loads. It is important to consider the structural flexibility of the jack-up legs and crane when modeling the installation of offshore wind turbine blades.acceptedVersion© 2018. This is the authors’ accepted and refereed manuscript to the article. Locked until 26.7.2020 due to copyright restrictions. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0

Intercomparison of in-situ aircraft and satellite aerosol measurements in the stratosphere

Aerosol composition and optical scattering from particles in the lowermost stratosphere (LMS) have been studied by comparing in-situ aerosol samples from the IAGOS-CARIBIC passenger aircraft with vertical profiles of aerosol backscattering obtained from the CALIOP lidar aboard the CALIPSO satellite. Concentrations of the dominating fractions of the stratospheric aerosol, being sulphur and carbon, have been obtained from post-flight analysis of IAGOS-CARIBIC aerosol samples. This information together with literature data on black carbon concentrations were used to calculate the aerosol backscattering which subsequently is compared with measurements by CALIOP. Vertical optical profiles were taken in an altitude range of several kilometres from and above the northern hemispheric extratropical tropopause for the years 2006-2014. We find that the two vastly different measurement platforms yield different aerosol backscattering, especially close to the tropopause where the influence from tropospheric aerosol is strong. The best agreement is found when the LMS is affected by volcanism, i.e., at elevated aerosol loadings. At background conditions, best agreement is obtained some distance (>2 km) above the tropopause in winter and spring, i.e., at likewise elevated aerosol loadings from subsiding aerosol-rich stratospheric air. This is to our knowledge the first time the CALIPSO lidar measurements have been compared to in-situ long-term aerosol measurements. © 2019, The Author(s)