A Methodology for Site-Wide Structural Optimisation and Advanced Clustering of Monopile Foundations for Next-Generation Offshore Wind Turbines

Design space exploration of microprocessor is still a challenging task for processor designers. Due to the huge design space, it is hard to determine the optimal configuration of microarchitecture parameters to satisfy the target performance and power requirements within limited time at the early stage of processor design. In this paper, a Critical Path Analysis directed Design Space Exploration (CPADSE) methodology for design space exploration of microprocessors is proposed. In CPADSE, a dependence graph model is constructed using the profile information generated during the program simulation. Then the critical paths of the dependence graph model are computed and patterns of the critical path are identified. The microarchitecture parameters mostly affecting processor`s performance or other metrics can be identified using the Plackett-Burman design method, which is always referenced as sensitivity analysis. Then the result of critical path analysis and sensitivity analysis is further used to guide the selection of search direction in both SA-CPADSE and TB-CPADSE design space search algorithms, which are proposed in this paper. Experiment result shows that for the design space exploration on SPEC 2000 benchmarks, SA-CPADSE obtains 2x speedup over baseline design space exploration algorithm SA-DSE. Additionally, TB-CPADSE on average obtains 4.3x speedup over SA-CPADSE and 7x speedup over SA-DSE. At the end of this paper, we have a detailed discussion about how to extend CPADSE methodology to design space exploration of multicore processors.

Reinforced concrete (RC) frames are extensively used in construction of buildings worldwide. The conventional design of these buildings typically relies on a "trial and error" method, starting with initial dimensioning followed by validation of the preliminary design. This approach makes it difficult to calculate potential cost savings in materials, while maintaining structural safety. In recent decades, the need for more efficient, safe and rational seismic design procedures has led to an increasing interest in structural optimisation of RC frames. However, due to the complex non-linear behaviour of RC frames, arriving at their optimum design under earthquake excitations is challenging. Even at serviceability limit state, concrete cracking can lead to significant stiffness changes and redistribution of inertial forces, phenomena that are normally expected after steel yielding. To mitigate these drawbacks, numerous combinations of section dimensions and reinforcement arrangements can be considered as design variables during a structural size optimisation process. However, this is seldom done for RC frames, as it requires seismic analyses with a high level of accuracy, which can be computationally expensive. Meanwhile, design optimisation has been identified as a feasible way to reduced embodied carbon emissions in construction, and therefore, a change of design paradigms is necessary. The article aims to critically review the major developments in recent seismic design optimisation studies on RC buildings, focusing on structural size optimisation, with the goal of identifying the main achievements and limitations. Different design objectives in current seismic design optimisation procedures are first summarised. The key steps in structural optimisation are then discussed, including design variables, design constraints, application of optimization methodologies, and evaluation of seismic performance. Finally, the research gaps in this field are identified, and suggestions are provided for future research directions. This article contributes towards the development of more efficient seismic design methods for RC structures, which in turn can lead to more sustainable construction.

Horizontally Partitioned Caches (HPCs) are a promising architectural feature to reduce the energy consumption of the memory subsystem. However, the energy reduction obtained using HPC architectures is very sensitive to the HPC parameters. Therefore it is very important to explore the HPC design space and carefully choose the HPC parameters that result in minimum energy consumption for the application. However, since in HPC architectures, the compiler has a significant impact on the energy consumption of the memory subsystem, it is extremely important to include compiler while deciding the HPC design parameters. While there has been no previous approaches to HPC design exploration, existing cache design space exploration methodologies do not include the compiler effects during DSE. In this paper, we present a Compiler-in- the-Loop (CIL) Design Space Exploration (DSE) methodology to explore and decide the HPC design parameters. Our experimental results on HP iPAQ h4300-like memory subsystem running benchmarks from the MiBench suite demonstrate that CIL DSE can discover HPC configurations with up to 80% lesser energy consumption than the HPC configuration in the iPAQ. In contrast, tradition simulation-only exploration can discover HPC design parameters that result in only 57% memory subsystem energy reduction. Finally our hybrid CIL DSE heuristic saves 67% of the exploration time as compared to the exhaustive exploration, while providing maximum possible energy savings on our set of benchmarks.

It is widely accepted that use of an Application Specific Instruction Set Processor (ASIP) in an embedded system can provide a solution which is much more flexible than ASICs and much more efficient than standard processors in terms of performance and power consumption. However a lack of an acceptable design methodology and supporting tools for ASIPs limits their use even today. We present in this paper a methodology for design space exploration of high performance VLIW ASIPs by modeling Application Specific Functional Units in Trimaran Compiler Infrastructure. To demonstrate the effectiveness of our strategy we consider two important applications FFT and Kalman Filter and perform compute intensive operations in these applications via special Functional Units. The results we obtain are very promising with up to 2x speed improvement.

An experimental study on wave forces on a vertical cylinder due to spilling breaking and near-breaking wave groups

The design and assessment of offshore structures, fixed or floating, against extreme and abnormal accidental events require special advanced analysis capabilities and can be dimensioning in certain situations. Such accidental events entail vessel collision/allision, dropped objects, fire, and explosion conditions. Only vessel impact and dropped objects are addressed herein. Allisions involving high impact speeds are also discussed. The structures considered include fixed platforms, floaters (Spar, FPSO, and Semi-submersible), and mobile offshore units. The paper shows how nonlinear FEA and simplified methods are applied both at the design stage and as assessment tools following an incident of accidental loading. It demonstrates that by making reasonable assumptions concerning the energy dissipation parameters during a collision/allision scenario, significant savings in computational and analysis efforts are realized while the reliability of the results is maintained. Both traditional low kinetic energy and abnormal high energy scenarios are evaluated. The paper also presents proposed repair solutions to some typical damage conditions and compares the different codes and standards (ISO, NORSOK, and API) with regards to the acceptability criteria. Introduction The design of offshore structures must account for accidental loadings with low probability of occurrence. Such accidental loadings include vessel collision/allision, dropped objects, fire, and explosion conditions. This paper is dedicated to vessel impact and dropped objects. Fire and blast resistance will be covered in future publications focusing on offshore applications. The FABIG (2009) and ASCE (2010) are currently the two main bodies dealing with fire and blast resistant structures with emphasis on buildings and petrochemical facilities. In addition to accidental supply ship impacts, some recent offshore facilities had to consider high speed ship bow impacts or allusions in order to ensure adequate safety especially when storage of petroleum or liquefied gas is involved. The objective of this paper is to present recent analysis capabilities that make it possible to realistically predict the energy absorption capabilities of offshore structures due to ship collision. This is important in order to ensure that the extent and consequence of the damage is acceptable. The acceptability criteria are set in the regulations and codes of practice as dependent on the associated collision risk level and consequence assessment. In the ISO standards; for example, hazards are categorized into three main groups, according to annual exceedance probability or return period:–Group 1 - hazards with 10–2 annual probability or return period of the order of 100 years–Group 2 - hazards with 10–3 annual probability or return periods of the order of 1000 to 10000 years–Group 3 - hazards with 10–4 annual probability or return periods well in excess of 10000 years Extreme conditions correspond to the 100 year conditions and are treated as ultimate limit state (ULS) events while accidental or abnormal events are associated with the 1000 or 10,000 year abnormal limit state (ALS) scenarios. A review of requirements in offshore regulations, standards and codes is given in Ghoneim (2008).

Many demanding streaming applications share functional and structural similarities with other applications in their respective domain, e.g., video analytics, software-defined radio, and radar. This opens the opportunity for specialization to achieve the needed efficiency and/or performance.Platforms integrating many accelerators (ACCs) are a primary approach for efficient, high-performance stream computing. However, designing one platform for each application is not economical due to the high costs of nonrecurring engineering (NRE) and time-to-market (TTM). To this end, the concept of domain platforms is proposed, which takes advantage of similarities across applications and designs one unified platform to accelerate a domain of applications instead of focusing on a single reference application. This dissertation approaches designing domain platforms from a function-level (kernel-level) acceleration through a heterogeneous ACC-rich platform, where each ACC is specialized to accelerate a particular function. There is a great challenge to select ACCs allocated in the domain platform, considering the large design space and performance balance across many applications. However, current Design Space Exploration (DSE) tools only focus on an individual application in isolation (e.g., one particular vision flow) for allocating a platform, but not a set of similar applications. Multiple applications are only considered in the application bindings to an existing platform. Hence, optimizations that occur due to considering multiple applications simultaneously are missed in platform design. New DSE methodologies and tools are needed with a broader scope of application sets instead of individual applications. This dissertation introduces a novel Domain Design Space Exploration (DmDSE) methodology that broadens the DSE scope from an individual application to allocating a new heterogeneous ACC-rich platform for many applications.This dissertation defines domain characteristics to express the inherent structural and functional similarities across applications and metrics to quantitatively assess domain platforms with a balanced focus across various applications. Two novel algorithms, Dynamic Score Selection (DSS) and GenetIc Domain Exploration (GIDE), are introduced to do DmDSE and allocate domain platforms, which improve performance over application-specific platforms by 58% and 75% when only considering monolithic (single function) ACCs. A finer granularity of ACCs is beneficial for generality and performance under an area constraint. Considering multi-granularity similarities across functions, Multi-Granularity DmDSE (MG-DmDSE) extends DSE through allocating finer granular and configurable ACCs and decomposing functions in the binding. MG-DmDSE produces a more general platform that benefited 87.5% of applications, while only 50% from GIDE. With a huge design space, DmDSE suffers from a long exploration time due to a large number of complex platform evaluations. Heuristics and machine learning methods are proposed to speed up DmDSE.This dissertation introduces Greedy Guided Mutation (GGM) to speed up the mutation in the GIDE algorithm, which calculates an ACC score according to current allocation to guide mutation. Alternatively, Rapid Domain Platform Performance Prediction (RDP^3) methods are introduced to replace a large number of the slow platform assessment in domain DSE, which avoids the complex application binding exploration. In the experiments, GGM reduces 84.8% of exploration time with a 0.23% loss of the final OpenVX domain platform's performance. RDP^3, using a machine learning method, yields an even more significant speedup, saving 90.8% of exploration time with only 0.0003% performance loss. DmDSE is a milestone to broaden DSE scope from individual applications to the domain level. It tremendously pushes the domain platform design from an experience-guided, manual effort into an automated process.--Author's abstract

In this paper, we present the findings of an interview study of game developers participating to a constrained game development event, Survival Mode 2016 game jam. Survival Mode 2016 was organized in Finnish Lapland as the northernmost jamming site of Global Game Jam (GGJ) 2016. The event differed from the typical Global Game Jam site in Finland in terms of participants being mostly experienced game developers and that there were additional design constraints for their projects. In addition to the global theme, the participants of the Survival Mode 2016 had an extra thematic constraint and the setting of the event itself created such constraints as limited Internet connectivity and power supply. The interviewees reflected on their projects and experiences with design constraints providing interesting insight to the role of design constraints in game development and the difference between a jam setting and commercial game creation projects. These observations can be utilized in further studies of game design constraints as well as in the design of different game jam events.

After the Fukushima nuclear accident in Japan, whether the structural safety of the nuclear power plant (NPP) can be guaranteed under an earthquake has been of wide concern. Automatic seismic trip systems (ASTS) have been deployed in NPPs. There are generally two units or more double units on the one NPP site, and the vibration energy of the structure can certainly affect its adjacent structures through the soil, and there is energy transfer and conversion between adjacent structures. At present, the distance between two reactors of NPPs of different reactor types is generally 100–200 m (this distance is referring to the distance between the centers of two reactors, which is slightly different for different reactor types). In the past, seismic instruments were used in the ASTS and the setting of shutdown threshold, so the impact of only one unit was considered in the structural analysis of NPPs, and the interaction of two reactors through site conditions was not considered. In addition, as the site conditions of NPPs become more and more complex, it is necessary to consider the impact of one reactor structure on another reactor structure through the soil on the same site under an earthquake. In order to analyze the influence of structure–soil–structure interaction (SSSI), a three-dimensional refined finite element model of NPPs is established in this paper. The soil–structure interaction (SSI) is considered by using viscoelastic boundary. The seismic responses of different positions of the raft foundation and NPP structure, under the conditions of considering SSI effect (one reactor) and SSSI effect (two reactors), are compared. The influence of SSSI effect on the seismic responses of the raft foundation and NPP structure is revealed. It is proposed that SSSI effect should be reasonably considered according to the site conditions for the structural analysis of NPPs for the NPP ASTS.

Using ordinary and simple kriging was carried on an estimated and simulated mapping and cross-section of the thickness of the soft cohesive soil layer found below the sea floor, and the soil water content until 100m depth, respectively. The goals of this geostatistical research is to have a better characterization of the marine soil in the Gulf of Mexico. Introduction New techniques are constantly incorporated in site and ground investigation procedures in order to achieve a better characterization of marine soils Simultaneously, reliability methods are increasingly used in offshore engineering. In both regards, geostatistical methods can be extremely useful. They can be used for modeling spatial variations of soil properties as well as to assess the ensuing uncertainty in the design of offshore structures. When information based on good quality and systematic geotechnical exploration is available, geostatistical modeling of the spatial variability of geotechnical parameters makes it possible to obtain reliable estimates of the soil properties in locations where no sampling or field testing was performed and to assess the remaining uncertainty regarding the soil conditions. This paper illustrates the usefulness of geostatistics as an auxiliary quantitative method for obtaining a better description of the marine soils of the Sonda de Campeche in the Gulf of Mexico. Spatial variability of two parameters is assessed: the thickness of the soft cohesive soil layer found below the sea floor, and the soil water content until a depth of 100 m. The maps and cross-sections obtained through geostatistical estimation will be used for the analysis of the foundation of future offshore structures. Random Field Theory Soil parameters show random spatial variations that constitute an important source of uncertainty in geotechnical design. These variations and the ensuing uncertainty can be modeled using the theory of spatial random fields (Auvinet, 2002) Let V(X) be a geotechnical variable either physical (i.e. water content), mechanical (i.e. undrained shear strength), or geometric type (i.e. thickness of a certain stratum), defined at points X of the domain of interest RP (p = 1,2 or 3). If at each point of the domain this variable is regarded as random, the set of these random variables constitutes a random field.

To investigate the dynamic behavior of offshore structures to irregular waves, we conducted model tests using frame and column models, and took field measurements of the vibrations of an offshore structure installed in 80 m of water. We also conducted theoretical analyses of the dynamic response of offshore structures to irregular waves, and compared calculated values with the results of model tests and actual field measurements. From these studies to evaluate the dynamic response characteristics of offshore structures to irregular waves, we obtained data necessary for the dynamic design of deep-water offshore structures. INTRODUCTION The design of large offshore structures to be installed in deep water must be based on dynamic analysis, but strict analysis of their dynamic behavior requires frequent use of large computers. To avoid this costly procedure, it is necessary to employ either hypotheses or the approximation method in analyzing phenomena ranging from sea-surface fluctuations to vibration responses. To be analyzed by the approximation method, vibration phenomena must be clearly defined, so we analyzed the dynamic behavior of offshore structures under the influence of irregular waves by conducting model tests. We also conducted field measurements of the vibrations of an offshore platform. Further, we determined the responses by linear analysis using relatively simple models and evaluated the dynamic behavior characteristics by comparing calculated and measured results. The model tests comprised free vibration tests in which column and frame models were tested both in the submerged state and in air and dynamic response tests in which the models were tested using two dimensional irregular waves. In the former tests, the natural periods, damping constants and vibration modes of the models were determined in the latter, the fluid force coefficients of irregular waves and the response displacements and stress range frequency distribution characteristics of offshore structures were obtained. In the field vibration measurements, the natural period and damping constant of the platform were determined from its response power spectra in the tremor state. Our field measurements also revealed wave response characteristics of offshore structures during the passage of a storm center and their vibration characteristics during drilling. In the theoretical analyses, a lumped-mass model was substituted for the structure using the natural periods and damping constants obtained in the model and field tests. Borgman's wave force spectrum1 was used for the wave force spectrum in determining the response values. Then these theoretical response values were compared with the measured values. OUTLINE OF THE MODEL TESTS The column and frame models shown in Fig. 1 were used in the model tests. They were made of Acrylite. In the free vibration tests, plates each weighing about 5 kg were used as a load on the deck of each model.

Construction of offshore structures is more complex than onshore structures in terms of structural response and its loading system. The high dependency on the environment with high level of uncertainties is the main factor that contributes to the complexity of design and construction process. Better understanding on the type of structures and load exposed to it are required to maintain the high integrity of the operation life. An overview of the design and analysis of offshore structure in the case of fixed platform will be discussed in this paper. It comprises of the fundamental principle of wave dynamic, the dominant load acting on the structure, method used to quantify the responses and probability of failure that should be considered at the design stage. It is mainly to provide understanding and guideline for the purpose of the design phase. Description in details can be obtained through further reading based on references that have been cited in the content.

Little is known about wave forces caused by extreme breaking waves in deep water. This study presents certain results from simulation of the kinematics of plunging breakers in deep water obtained both from carefully controlled laboratory experiments and from numerical simulation. In the experiments extreme waves are generated in three ways:The dispersion properties of gravity waves are used to generate a transient situation in which the energy of the individual waves in a wave train concentrates towards a specified point in time and space, resulting in one extreme wave;Very steep Stokes waves of finite amplitude are forced to break at a selected point in deep water due to superposition of a subharmonic disturbance;Very steep Stokes waves are forced to break at a selected point due to superposition of' a superharmonic disturbance. In the numerical model, the development of the (breaking) wave profile, the particle velocities and the accelerations within the wave are simulated. We exact free-surface conditions. are satisfied, and good results are achieved up to the point where the overhanging crest hits the wave front. Comparison of the plunging breakers generated in the wave flume and calculated numerically, shows good agreement with respect to the wave geometry. The measured and calculated velocities also agree well at depths larger than approximately one wave amplitude below the mean water level. In the wave crest near the plunging jet, the measured velocities are, however, 1.5 times as large as the calculated velocities. This may be due to the difference in the method of generating the plunging breakers in the two cases. Experiments so far have now confirmed that transient, near breaking and breaking waves attain velocities up to 2.8 times the first order phase velocity. The results may be applied to the operation and evaluation of stability of ships under severe sea conditions. Further, they provide the basis for the estimation of wave drag and inertia forces from extreme breaking waves in deep water with many applications for the design and safety of offshore structures. INTRODUCTION In order to evaluate safety at sea, a basic need is a prediction of the characteristics of extreme sea states. There is an extensive literature on the subject of the' mysterious disappearances of ships, both large and small. A high percentage of these mysteries can be solved by even a cursory study of so-called "freak waves" (a freak being "capricious change"), which are more correctly termed episodic waves. By definition an episode is a recurring event, and so it is with huge waves on the continental shelves. Episodic waves occur in virtually all such areas during certain predictable times of the year. The origin of episodic waves is not fully understood. It is believed that a shoaling mechanism, unique to a certain geographic location as well as a particular random phase relationship between waves, can account for the phenomenon.

Characteristics of hurricane-induced wind, wave, and storm surge maxima along the U.S. Atlantic coast

Applications and architectures for embedded systems are becoming more and more complex. It is difficult to analyze complex embedded applications at early stages of the design flow without generic automated tools and methodologies. Consequently, application analysis under the real input conditions is becoming more and more important. Existing application analysis methodologies mainly focus on a single design objective. A general purpose application analysis methodology is required to satisfy multiple objectives of early design space exploration. This article proposes a general purpose application analysis methodology based on a visitor design pattern. High level source specifications are transformed into a trace tree representation by dynamic analysis. Trace tree representation is analyzed by using a visitor design pattern to get run-time characteristics of the application. Among other outcomes, application characterization and average inherited parallelism are key concerns in this article. Experimental results with MPEG-2 video decoder shows viability of the proposed methodology.