328 research outputs found
On Prediction of User Destination by Sub-Trajectory Understanding
No full textDestination prediction is known as an important problem for many location based services (LBSs). Existing solutions generally apply probabilistic models to predict destinations over a sub-trajectory, but their accuracies in fine-granularity prediction are always not satisfactory due to the data sparsity problem. This paper presents a carefully designed deep learning model called TALL model for destination prediction. It not only takes advantage of the bidirectional Long Short-Term Memory (LSTM) network for sequence modeling, but also gives more attention to meaningful locations that have strong correlations w.r.t. destination by adopting attention mechanism. Furthermore, a hierarchical model that explores the fusion of multi-granularity learning capability is further proposed to improve the accuracy of prediction. Extensive experiments on Beijing and Chengdu real datasets finally demonstrate that our proposed models outperform existing methods without considering external features.Jing Zhao, Jiajie Xu, S, Rui Zhou, Pengpeng Zhao, Chengfei Liu, Feng Zh
Modelling Fluid-structure Interaction in Offshore Photovoltaics
No full textThe main aim of the research presented in this report is investigating analytical methods to model fluid-structure interaction in large-scale offshore floating photovoltaics. The model that was attempted to be solved analytically is based on a model presented by Pengpeng Xu (2022).The dimensions in the equations were removed. Applying a perturbation method yielded hierarchic partial differential equations by introducing the wave amplitude divided by the depth of the ocean as a small perturbation parameter. The analytical solution of the first order problem was found by applying separation of variables and by using a Fourier transform. For certain classes of problems it is shown in this report that it is possible to analytically solve a model for fluid-structure interaction in offshore solar farms for various initial conditions.Applied Mathematic
Numerical Simulation of the Interaction of A Membrane with Water with A Free Surface: Simulation of An Experiment by L. Rizos
No full textIn order to collect validation data for the study of the mechanism of fluid-structure interaction (FSI), an lab experiment was conducted by L. Rizos in the towing tank, 3ME,TUDelft in 2016. The concept of the experiment is shown in the figure 1. A cylindrical container is partially filled with water. A small cylindrical oscillator with flexible bottom is placed in the container. The oscillator is driven harmonically by a motor. During the experiment, the deflection of the flexible bottom, the motion of the free surface and the driven force were monitored and recorded. The figure 2 is the photo of the experiment. In order to better understand Rizos’ experiment, a series of researches are conducted in the Section Ship Hydromechanics, which includes analytical simulation and several numerical simulations with different methods. A linear algorithm is developed in this thesis, which applies implicit, monolithic (solving the fluid domain and structure domain simultaneously) and one-step (without iteration) methods. The model of the numerical simulation is shown in the figure 3, a small cylinder with flexible bottom is placed in the big cylindrical container. The two cylinders are partially filled with water and the still water levels are the same. The inner cylinder does not moves up and down as a whole. The oscillation of the whole system is the result of the initial wave elevation in the fluid domain and/or the initial deflection in the structure domain. The result of the numerical simulation is shown in the figure 4. The effect of added mass for a structure submerged in water results in that smaller eigen frequency of the structural vibration. The structure interacts with the ambient fluid, especially the free surface. For a pre-defined initial condition, the influence of the free surface results in the mode dispersion. The numerical periods of this FSI system agrees with the analytical periods. Significant numerical dissipation exists in the 1st order time integration techniques. Thus, the second order implicit Adam Moulton method, i.e., the trapezoidal rule, is implemented to improve the algorithm. in this way, the numerical dissipation is decreased drastically (5% less dissipation after 10 periods) without increasing the computational costs.Offshore and Dredging Engineerin
Conditional Loss of Pten in Myogenic Progenitors Leads to Postnatal Skeletal Muscle Hypertrophy but Age-Dependent Exhaustion of Satellite Cells
No full textSummarySkeletal muscle stem cells (satellite cells [SCs]) are normally maintained in a quiescent (G0) state. Muscle injury not only activates SCs locally, but also alerts SCs in distant uninjured muscles via circulating factors. The resulting GAlert SCs are adapted to regenerative cues and regenerate injured muscles more efficiently, but whether they provide any long-term benefits to SCs is unknown. Here, we report that embryonic myogenic progenitors lacking the phosphatase and tensin homolog (Pten) exhibit enhanced proliferation and differentiation, resulting in muscle hypertrophy but fewer SCs in adult muscles. Interestingly, Pten null SCs are predominantly in the GAlert state, even in the absence of an injury. The GAlert SCs are deficient in self-renewal and subjected to accelerated depletion during regeneration and aging and fail to repair muscle injury in old mice. Our findings demonstrate a key requirement of Pten in G0 entry of SCs and provide functional evidence that prolonged GAlert leads to stem cell depletion and regenerative failure
“Just a Slogan”
No full textThe past 10 years have seen a huge influx of women's fashion magazines into the urban centres of mainland China. This article explores shifting conceptions of female identity in the "new" consumerist China via an examination both of the magazines themselves and of the young women who are their target readers. Based on interviews conducted with young women in Guangzhou, the interpretive structures through which they discuss the images they found in the magazines are analysed, and the ways in which they negotiate both the identities on offer in the magazines and the contradictions between these identity positions and those experienced elsewhere in their lives. Arguing that, despite their lack of self-reflexivity, the images found in these magazines offer no greater promise of a coherent femininity than their western counterparts, it draws comparisons with the post-feminism of contemporary western popular culture through a shared loss of a specifically feminist subject position
Author response
No full textThe diverse cell types and the precise synaptic connectivity between them are the cardinal features of the nervous system. Little is known about how cell fate diversification is linked to synaptic target choices. Here we investigate how presynaptic neurons select one type of muscles, vm2, as a synaptic target and form synapses on its dendritic spine-like muscle arms. We found that the Notch-Delta pathway was required to distinguish target from non-target muscles. APX-1/Delta acts in surrounding cells including the non-target vm1 to activate LIN-12/Notch in the target vm2. LIN-12 functions cell-autonomously to up-regulate the expression of UNC-40/DCC and MADD-2 in vm2, which in turn function together to promote muscle arm formation and guidance. Ectopic expression of UNC-40/DCC in non-target vm1 muscle is sufficient to induce muscle arm extension from these cells. Therefore, the LIN-12/Notch signaling specifies target selection by selectively up-regulating guidance molecules and forming muscle arms in target cells. DOI:http://dx.doi.org/10.7554/eLife.00378.001
‘Just a Slogan’: Individualism, Post-Feminism and Female Subjectivity in Consumerist China
No full textMotion based cable integrity limits for quadrant assisted pull-in operations on submarine inter-array cables
No full textThe installation of subsea cables connecting offshore wind turbines to the grid is a delicate process. This is especially the case for the operation of connecting the second end of the cable to the turbine. The applied method of using a quadrant means that in the workability analyses, multibody dynamics, line dynamics and sea state dynamics need to be combined, resulting in lengthy simulation requirements. The objective of this thesis is to determine vessel motion based limits to cable integrity in order to simplify workability analyses. This method allows the problem to be analyzed in the frequency domain, resulting in computational efficiency gains. In order to arrive at the desired result a literature study is performed regarding cable loading and cable failure modes encountered during quadrant assisted cable pull-ins. On that basis a detailed investigation into the relations between vessel motion and mechanical cable responses is carried out. To achieve this, a representative cable and a set of high but realistically encountered sea states are simulated. The obtained relations are then compared to the cable integrity limits for curvature, tension and compression to acquire limits expressed in terms of motion parameters such as acceleration, velocity and displacement. The results from these simulations show that: 1) maximum cable tension is closely correlated to upward heave velocity of the crane tip, 2) maximum cable compression is closely correlated to downward heave velocity, 3) maximum curvature is most closely correlated to downward heave velocity. It is concluded from the results that the cable response can be determined from the crane tip heave motion, which in turn is known from the vessel motions. This means that analysis of such a problem is possible in the frequency domain. As the results show that heave motion is governing in cable failure, heave compensation in the crane is recommended for the operations considered. In addition, an enhancement of the analysis process is proposed by extracting the linear relations and vessel motion limits from a small set of time domain simulations and assessing the situation thoroughly in a frequency domain analysis. The configurations considered exclude any effects added by cable protection systems or interaction effects with rigid bodies in the vicinity of the cable. Even though the analysis process is generally applicable and constitutes a significant improvement in computational load, the obtained relations may be generalized further by implementing a closed formula relating vessel motion to cable failure, or application of the cable protection system to the assessed configuration. Additional research in these directions is encouraged.Offshore and Dredging Engineerin
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