687 research outputs found
Genuine output and genuine productivity of China\u27s provinces : a multiregional input-output analysis
This paper recalculates value added, capital formation, capital stock, and related multifactor productivity for China\u27s provinces by expanding on the genuine savings method proposed by the World Bank. Specifically, we construct China\u27s time-series multiregional input?output tables to account for the natural resource depletion and environmental damage that affect genuine output when considering inter-provincial trade. The results show that although the loss of natural capital in China\u27s provinces in terms of value added and investment has declined, the impact on productivity during the past decades is still significant and has even increased during the past decades
Self-optimization wavelet-learning method for predicting nonlinear thermal conductivity of highly heterogeneous materials with randomly hierarchical configurations
In the present work, we propose a self-optimization wavelet-learning method
(SO-W-LM) with high accuracy and efficiency to compute the equivalent nonlinear
thermal conductivity of highly heterogeneous materials with randomly
hierarchical configurations. The randomly structural heterogeneity,
temperature-dependent nonlinearity and material property uncertainty of
heterogeneous materials are considered within the proposed self-optimization
wavelet-learning framework. Firstly, meso- and micro-structural modeling of
random heterogeneous materials are achieved by the proposed computer
representation method, whose simulated hierarchical configurations have
relatively high volume ratio of material inclusions. Moreover,
temperature-dependent nonlinearity and material property uncertainties of
random heterogeneous materials are modeled by a polynomial nonlinear model and
Weibull probabilistic model, which can closely resemble actual material
properties of heterogeneous materials. Secondly, an innovative stochastic
three-scale homogenized method (STSHM) is developed to compute the macroscopic
nonlinear thermal conductivity of random heterogeneous materials. Background
meshing and filling techniques are devised to extract geometry and material
features of random heterogeneous materials for establishing material databases.
Thirdly, high-dimensional and highly nonlinear material features of material
databases are preprocessed and reduced by wavelet decomposition technique. The
neural networks are further employed to excavate the predictive models from
dimension-reduced low-dimensional data
PI-VEGAN: Physics Informed Variational Embedding Generative Adversarial Networks for Stochastic Differential Equations
We present a new category of physics-informed neural networks called physics
informed variational embedding generative adversarial network (PI-VEGAN), that
effectively tackles the forward, inverse, and mixed problems of stochastic
differential equations. In these scenarios, the governing equations are known,
but only a limited number of sensor measurements of the system parameters are
available. We integrate the governing physical laws into PI-VEGAN with
automatic differentiation, while introducing a variational encoder for
approximating the latent variables of the actual distribution of the
measurements. These latent variables are integrated into the generator to
facilitate accurate learning of the characteristics of the stochastic partial
equations. Our model consists of three components, namely the encoder,
generator, and discriminator, each of which is updated alternatively employing
the stochastic gradient descent algorithm. We evaluate the effectiveness of
PI-VEGAN in addressing forward, inverse, and mixed problems that require the
concurrent calculation of system parameters and solutions. Numerical results
demonstrate that the proposed method achieves satisfactory stability and
accuracy in comparison with the previous physics-informed generative
adversarial network (PI-WGAN).Comment: 23 page
Multi-scale modelling of the human left ventricle
In this paper, a multi-scale computational frame is proposed to simulate dynamics of the human left ventricle. First of all, a modified Level Set method is used to segment the cardiac magnetic resonance imaging and then reconstruct the 3D computational domain of the left ventricle. The Holzapfel-Ogden's nonlinear and anisotropic model is imposed to calculate the passive elastic response. The Fenton-Karma model with stimulus current is optimized to produce the reasonable membrane potential and intracellular calcium concentration. Based on the obtained calcium concentration, the active tension is calculated. Finally, the passive elastic response and the active tension of the left ventricle are coupled with the blood and the obtained fluid structure interaction is solved by the immersed boundary method. Our numerical results at end-diastole and end-systole are generally in good agreement with the clinical measurement and the earlier studies, which verifies the efficiency of the method
Influences of S-Wave Velocity to the Seismic Response of Silt Ground
By using of one-dimension equivalent linearzation seismic response analysis method, the study is performed to the different silt grounds. The influences of s-wave velocity uncertainty to the seismic acceleration peak, duration, response spectrum of silt ground are discussed in the paper. Following conclusions will he expected. (1) The relationship between the difference of seismic peak acceleration and the difference of s-wave velocity is in linear distribution approximately. The seismic peak acceleration is changed with the S-wave velocity. The seismic peak acceleration is much effected by the uncertainty of S-wave velocity. (2) The uncertainty of shear wave velocity has little influence on the seismic duration. (3) The long-period seismic response spectrum is much effected by the decreasing of shear wave velocity. Conversely, the moderate-period and short-period seismic response spectrum is much effected by the increasing of shear wave velocity. With the depth of silt layers extended, the seismic response spectrum is greater influenced by the uncertainty of shear wave velocity
Workflow-based Fast Data-driven Predictive Control with Disturbance Observer in Cloud-edge Collaborative Architecture
Data-driven predictive control (DPC) has been studied and used in various
scenarios, since it could generate the predicted control sequence only relying
on the historical input and output data. Recently, based on cloud computing,
data-driven predictive cloud control system (DPCCS) has been proposed with the
advantage of sufficient computational resources. However, the existing
computation mode of DPCCS is centralized. This computation mode could not
utilize fully the computing power of cloud computing, of which the structure is
distributed. Thus, the computation delay could not been reduced and still
affects the control quality. In this paper, a novel cloud-edge collaborative
containerised workflow-based DPC system with disturbance observer (DOB) is
proposed, to improve the computation efficiency and guarantee the control
accuracy. First, a construction method for the DPC workflow is designed, to
match the distributed processing environment of cloud computing. But the
non-computation overheads of the workflow tasks are relatively high. Therefore,
a cloud-edge collaborative control scheme with DOB is designed. The low-weight
data could be truncated to reduce the non-computation overheads. Meanwhile, we
design an edge DOB to estimate and compensate the uncertainty in cloud workflow
processing, and obtain the composite control variable. The UUB stability of the
DOB is also proved. Third, to execute the workflow-based DPC controller and
evaluate the proposed cloud-edge collaborative control scheme with DOB in the
real cloud environment, we design and implement a practical workflow-based
cloud control experimental system based on container technology. Finally, a
series of evaluations show that, the computation times are decreased by 45.19%
and 74.35% for two real-time control examples, respectively, and by at most
85.10% for a high-dimension control example.Comment: 58 pages and 23 figure
MC-NeRF: Muti-Camera Neural Radiance Fields for Muti-Camera Image Acquisition Systems
Neural Radiance Fields (NeRF) employ multi-view images for 3D scene
representation and have shown remarkable performance. As one of the primary
sources of multi-view images, multi-camera systems encounter challenges such as
varying intrinsic parameters and frequent pose changes. Most previous
NeRF-based methods often assume a global unique camera and seldom consider
scenarios with multiple cameras. Besides, some pose-robust methods still remain
susceptible to suboptimal solutions when poses are poor initialized. In this
paper, we propose MC-NeRF, a method can jointly optimize both intrinsic and
extrinsic parameters for bundle-adjusting Neural Radiance Fields. Firstly, we
conduct a theoretical analysis to tackle the degenerate case and coupling issue
that arise from the joint optimization between intrinsic and extrinsic
parameters. Secondly, based on the proposed solutions, we introduce an
efficient calibration image acquisition scheme for multi-camera systems,
including the design of calibration object. Lastly, we present a global
end-to-end network with training sequence that enables the regression of
intrinsic and extrinsic parameters, along with the rendering network. Moreover,
most existing datasets are designed for unique camera, we create a new dataset
that includes four different styles of multi-camera acquisition systems,
allowing readers to generate custom datasets. Experiments confirm the
effectiveness of our method when each image corresponds to different camera
parameters. Specifically, we adopt up to 110 images with 110 different
intrinsic and extrinsic parameters, to achieve 3D scene representation without
providing initial poses. The Code and supplementary materials are available at
https://in2-viaun.github.io/MC-NeRF.Comment: This manuscript is currently under revie
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