The traditional joint migration inversion (JMI) technology faces the amplitude-versus-offset (AVO) challenge, which has been demonstrated before. We now apply JMI to 1.5-dimensional (1.5D) media, and use a velocity model and a density model to parameterize its solution space. As physically correct one-way propagation, reflection and transmission operators can be analytically formulated in 1.5D JMI, the AVO challenge is thus resolved. In this paper, we derive the complete theory behind the gradient calculation in 1.5D JMI, and further use a 1.5D synthetic example to demonstrate its correctness. This work is an important component of the 1.5D JMI theory, which will have applications in (locally) horizontally layered media containing strong multiple generators.

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Joint migration inversion (JMI) technology has great potential in exploiting multiples in seismic data for both velocity model building and seismic migration, but it faces the previously published amplitude-versus-offset (AVO) challenge: the angle-independent wavefield modeling used in the current JMI cannot simulate the correct AVO effect in data, but this modeling engine is still required in order to avoid over-parameterizing a solution space. By using a velocity model and a density model to parameterize the solution space, the AVO challenge can be adequately addressed by one-way operators for 1.5-dimensional (1.5D) media. In this paper, we propose a new concept, which is named 'inverse propagation' of receiver wavefields, for JMI in 1.5D media, and we derive the complete theory behind this new concept. We will demonstrate that our inverse propagation is a physically inverse process to reconstruct wavefields in the subsurface with the effects from transmission, reflection and multiples correctly accounted for, while the old backward propagation scheme for receiver wavefields in the previous JMI technology is a not satisfying approximation. This work paves a solid way to further develop the 1.5D JMI theory.@en

This graduation studio explores the potential of a landscape-based regional design approach to contribute to more resilient coastal landscapes around the globe. Such an approach addresses the interaction between the natural and urban landscape throughout the scales of space and time. It takes the landscape as the basis for sustainable urban development and employs research through design as a strategy to explore the possibilities of landscape architecture principles for water-sensitive design, nature-based solutions, heritage protection, and socio-ecological inclusive development. This landscape approach is transdisciplinary in nature and exploits the power of design to address the complex challenges of our times while connecting long-term strategies and short-term interventions. The projects presented here showcase the wide range of possibilities of the landscape-approach in nature conservation, reduce flood risks, promote sustainable urban transformation and achieve a symbiosis between nature and culture.@en

After a previous review of the grain-size characteristics of in situ (primary) fine-grained aeolian deposits, reworked (secondary) aeolian deposits, as modified in lacustrine environments and by alluvial and pedogenic processes, are discussed in this paper. As a reference, the grain-size characteristics of primary loess deposits are shortly described. Commonly, pedogenesis and weathering of primary loess may lead to clay neoformation and thus to an enrichment in grain diameters of 4–8 μm, a size which is comparable to the fine background loess. Remarkably, the modal grain-size values of primary loess are preserved after re-deposition in lakes and floodplains. But, secondary lacustrine settings show a very characteristic admixture with a clayey population of 1–2,5 μm diameter due to the process of settling in standing water. Similarly, alluvial settings show often an addition with coarse-grained sediment supplied by previously eroded sediment. However, floodplain settings show also often the presence of pools and other depressions which behave similarly to lacustrine environments. As a result, alluvial secondary loess sediments are characterized by the poorest grain-size sorting when compared with the other secondary loess and primary loess. Despite the characteristic texture of each of these deposits, grain-size characteristics of the described individual sediment categories are not always fully diagnostic and thus grain-size analysis should be complemented by other information, as sedimentary structures and fauna or flora, to reliably reconstruct the sedimentary processes and environments.

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Joint migration inversion (JMI) is a recently developed technology that aims at incorporating the seismic velocity model update and acoustic migration, including all multiple scatterings, into one closed-loop process. Full waveform inversion (FWI) is a commonly accepted technology for velocity model building, and reverse-time migration (RTM)is the main method adopted for depth imaging. In this paper, for the first time we are going to use a 2D realistic deep water model to benchmark JMI against a workflow of FWI combined with RTM. With some insights on JMI gained from this comparison study, we believe FWI-JMI should be the road ahead.@en

Joint migration inversion (JMI) is a recently proposed full wavefield inversion method, which tries to minimize the mismatch between observed reflection data and forward modeled data, which is based on decoupled velocity and reflectivity models. Transmission effects and surface/internal multiples are included in the forward modeling process using a multi-dimensional version of the Bremmer series. However, since the current implementation of JMI uses an angle-independent reflectivity model, it cannot easily handle large-offset data due to the amplitude versus ray-parameter (AVP) effect. In this paper, we propose to use a zero-lag cross-correlation objective function of redatumed wavefields to mitigate this AVP challenge in JMI. This objective function can help to relax the requirement for strong amplitude matching happening in the least-squares sense and focus more on the similarity between the modeled and the measured data during inversion. For the reflectivity update, by weighting the corresponding redatumed residual wavefield, the correct value of reflectivities is mostly preserved. For the velocity update, we weight the redatumed residual to minimize the amplitude influence and emphasize only phase information. We demonstrate the effectiveness of our new method with a velocity model containing a strongly scattering overburden and a 2D realistic deep water model.@en

This paper aims to investigate stress ratio effect on fibre bridging significance in mode I fatigue delamination growth of composite materials. Fatigue resistance curves (R-curves) of different stress ratios are determined and compared with the quasi-static R-curve. The fatigue R-curve of a high stress ratio is similar to the quasi-static results. However, fatigue resistance of a low stress ratio is smaller than quasi-static resistance. These indicate that fibre bridging significance is stress ratio dependent. More bridging fibres can be generated in delamination of a high stress ratio, as compared to that of a low stress ratio. This can lead to fatigue bridging laws are stress ratio dependent and fatigue delamination is block load sequence dependent.@en

Fibre bridging can significantly enhance delamination resistance making the use of a single Paris resistance curve to determine fatigue crack growth insufficient. An empirical Paris-type relation has been developed in a previous study to take fibre bridging into account in fatigue delamination growth. This relation was developed by correlating the Paris constants C and n to the amount of fibre bridging. This paper provides a further investigation on the interface configuration effect on fatigue delamination growth, illustrating the significance of fibre bridging. The results demonstrated that more bridging fibres can be generated in a multidirectional interface, making both log(C) and n significantly depend on fibre bridging. Thus, the method proposed in the previous study is further extended to take into account of the interface configuration effect.@en

Surrogate-based Optimization is a useful approach when the objective function is computationally expensive to evaluate, compared to Simulation-based Optimization. In the surrogate-based method, analytically tractable “surrogate models” (also known as “Response Surface Models — RSMs” or “metamodels”), are constructed and validated for each optimization objective and constraint at relatively low computational cost. They are useful for replacing the time-consuming simulations during the optimization; quickly locating the area where the optimum is expected to be for further search; and gaining insight into the global behavior of the system. Nevertheless, there are still concerns about the surrogate model accuracy and the number of simulations necessary to get a reasonably accurate surrogate model. This paper aims to unveil: 1) the possible impacts of problem scale and sampling strategy on the surrogate model accuracy; and 2) the potential of Surrogatebased Optimization in finding high quality solutions for building envelope design optimization problems. For this purpose, a series of multi-objective optimization test cases that mainly consider daylight and energy performance were conducted within the same time frame. Then, the results were compared, in pair, based on which discussions were made. Finally, the corresponding conclusions were obtained after the comparative study.@en

Multidirectional DCB specimens with different thicknesses were manufactured and tested to have in-depth understanding of delamination behavior in composite laminates. The initiation crack growth is demonstrated to be ply orientation and thickness independent. However, interlaminar resistance and damage mechanisms in delamination growth are significantly related to the interface configuration as well as thickness. Fractography analysis demonstrated that resistance difference between unidirectional and multidirectional DCB specimens is related to damage mechanisms. Optical microscope observation revealed that crack path in the multidirectional specimens is zigzag. This phenomenon becomes vague with thickness increase. The appearance of zigzag crack indicates both interlaminar and intralaminar damage can occur in the delamination growth. However, interlaminar damage becomes the dominant failure mode in the thick specimens. SEM (Scanning Electron Microscope) observation demonstrated fibre prints and cusps are two typical morphologies located on the fracture surface. These features are even more significant in the multidirectional interface with thickness decrease. This paper will conclude that interface configuration and specimen thickness have significant effects on the damage mechanisms and interlaminar resistance during delamination growth in composite laminates. It is, therefore, insufficient to apply the unidirectional DCB specimen with a given thickness to determine delamination growth and damage mechanisms of a composite material.@en

Delamination is one of the most important damage in composite materials. It can propagate under fatigue loading and cause failures of composite structures. With the application of damage tolerance design philosophy in engineering and requirement of light weight structures in advanced aircrafts, how to characterize fatigue delamination growth behavior in composite materials and develop reliable prediction models become critical issues for the application of these materials. A large amount of studies have been conducted on the characterization of fatigue delamination growth under constant amplitude loading in composite materials. However, little attention has ever been put into the block loading sequence effect on delamination growth. Referring to fatigue crack growth in metals, shielding mechanism of plasticity deformation around the crack front plays a dominant role in the loading sequence effect. Fibre bridging, acting as the shielding mechanism, therefore can contribute to the loading sequence effect on fatigue delamination growth in composite materials. Double Cantilever Beam (DCB) specimens were designed and manufactured for the mode I fatigue delamination tests with HI-HI and LO-HI block loading sequences. Paris relation was subsequently used to interpret the experimental results. It demonstrates there is an obvious loading sequence effect on fatigue delamination growth in composite materials. The fatigue crack growth in the HI-HI block loading is slower than it in the LO-HI block loading.@en

The design of sport buildings has great impact on top-sport as well as on recreational sport-activities. It implies challenging tasks in meeting the performance-requirements. This includes the control of factors like daylight/lighting, air flow, thermal conditions, just to name a few. Such factors impact the performance of athletes and are hard to control in large sport halls; their control is even harder when the public/audience is located within the halls and require different climate conditions. While mechanical installations are often needed during competitions in order to guarantee constant conditions, relaying on mechanical installations during the daily and recreational use of the venues challenges their medium/long term sustainability. Computational form finding approaches can favour the achievement of high-performing and sustainable sport buildings. In this light, the paper tackles the use of Multi-objective and Multidisciplinary design optimization. The paper presents the concept of Multi-objective Multidisciplinary design optimization techniques to support trade-off decisions between multiple conflicting design objectives and interdisciplinary design methodology, during the conceptual design of sport buildings. The proposed method is based on parametric modelling, performance simulation tools and algorithms for computational optimization, for which the paper tackles three specific aspects. First of all, due to the complexity of large sport buildings, the formulation of the optimization and the screening of the related design variables is crucial in order to obtain a meaningful design space, which helps reducing unnecessary computational burden. Secondly, assessing performance based on measurements and analyses is crucial and can be supported by performance simulations tools; however effectively integrating performance simulations tools in the early phase of the design requires new tools. In this light, a customized computational process for the rapid assessment of temperature and airflow patterns is presented. Thirdly, the process requires the combination of design optimization and design exploration, while searching for well-performing solutions. The importance of design exploration is emphasized also for sub-optimal solutions. In order to facilitate the design exploration, the combination of optimization algorithms, multi-variate analysis algorithms and options for exploring design solutions via an interactive dashboard connected to a database are presented. To exemplify the method, specific case studies are developed as collaboration between Delft university of Technology and South China university of Technology.@en