Calibration of Mars Energetic Particle Analyzer (MEPA)

The first Mars exploration mission of China(Tianwen-1)is scheduled to be launched in 2020;a charged particle telescope,the Mars Energetic Particle Analyzer(MEPA),is carried as one of the payloads on the orbiter.The MEPA is designed to measure solar energetic particles(SEPs)and galactic cosmic rays(GCRs)in the near-Mars space and in the transfer orbit from Earth to Mars.Before the launch,the MEPA was calibrated in ground experiments with radioactive sources,electronic pulses,and accelerator beams.The calibration parameters,such as energy conversion constants,threshold values for the triggers,and particle identification criteria,were determined and have been stored for onboard use.The validity of the calibration parameters has been verified with radioactive sources and beams.The calibration results indicate that the MEPA can measure charged particles reliably,as designed,and that it can satisfy the requirements of the Tianwen-1 mission.

Application and Prospect of Cold Hoop Confining Method in Psoriasis from Dermatopathology in Integrated Chinese and Western Medicine

In the pathological changes of psoriasis vulgaris,excessive proliferation of keratinocytes,proliferation of microvessels,infiltration of a large number of inflammatory cells,and great shortening of epidermal replacement time,are the manifestations of Qi and Yin depletion,and they all correspond with pathological changes of nutrient Qi and blood deficiency caused by excessive loss.The treatment of psoriasis should focus on cold straight fire,convergence and fixation.Therefore,it is feasible to treat psoriasis with hoop in theory,and it is found that"cold hoop confining medicine"may be more suitable for the treatment of psoriasis vulgaris in the gradual progress of the experiment.The research could provide theoretical basis for the application of cold hoop confining medicine represented by brusatol in psoriasis vulgaris and related diseases.

On Relationship between Pediatric Shi Ji and Fever

Based on the clinical effect of the treatment on 546 Pediatric Shi Ji fever cases, the thesis tries to explore the effectiveness of Traditional Chinese Medicine(TCM) treatment on Pediatric Shi Ji and the relationship between Pediatric Shi Ji and fever. The methodology applied is a retrospective analysis on the clinical curative effect of TCM treatment on Shi Ji fever cases in our hospital from January 2008 to December 2012. And the results show that a total effective rate of 96.3% could be guaranteed through either oral Chinese Medicinal Herbs, Chinese Medicine Enema, Massage Therapy, or navel administration with TCM. The thesis holds that Pediatric Shi Ji may cause fever, which could be cured simply by applying TCM treatment (promoting digestion to eliminate stagnation) with less or no use of antibiotics.

Automated regression test method for scientific computing libraries:Illustration with SPHinXsys

Scientific computing libraries,whether in-house or open-source,have witnessed enormous progress in both engineering and scientific research.Therefore,it is important to ensure that modifications to the source code,prompted by bug fixing or new feature development,do not compromise the accuracy and functionality that have been already validated and verified.This paper introduces a method for establishing and implementing an automatic regression test environment,using the open-source multi-physics library SPHinXsys as an illustrative example.Initially,a reference database for each benchmark test is generated from observed data across multiple executions.This comprehensive database encapsulates the maximum variation range of metrics for different strategies,including the time-averaged,ensemble-averaged,and dynamic time warping methods.It accounts for uncertainties arising from parallel computing,particle relaxation,physical instabilities,and more.Subsequently,new results obtained after source code modifications undergo testing based on a curve-similarity comparison against the reference database.Whenever the source code is updated,the regression test is automatically executed for all test cases,providing a comprehensive assessment of the validity of the current results.This regression test environment has been successfully implemented in all dynamic test cases within SPHinXsys,including fluid dynamics,solid mechanics,fluid-structure interaction,thermal and mass diffusion,reaction-diffusion,and their multi-physics couplings,and demonstrates robust capabilities in testing different problems.It is noted that while the current test environment is built and implemented for a particular scientific computing library,its underlying principles are generic and can be easily adapted for use with other libraries,achieving equal effectiveness.

An efficient multi-resolution SPH framework for multi-phase fluid-structure interactions

Applying different spatial and temporal resolutions for different sub-systems is an effective approach to increase computational efficiency for particle-based methods. However, it still has many challenges in terms of achieving an optimized computational efficiency and maintaining good numerical robustness and accuracy for the simulation of multi-phase flows involving large density ratio and interacting with rigid or flexible structures. In the present work, based on the multi-resolution smoothed particle hydrodynamics(SPH) method [Zhang et al., JCP 429, 110028(2021)], an efficient multi-resolution SPH framework for multi-phase fluid-structure interactions(FSI) is proposed. First, an efficient multi-phase model, exploiting different density reinitialization strategies instead of applying different formulations to implement mass conservation to the light and heavy phases, respectively,is developed and the same artificial speed of sound for both phases can be used. Then, the transport velocity formulation is rewritten by applying temporal local flow state dependent background pressure to eliminate the unnatural voids, unrealistic phase separation and decrease the numerical dissipation. Finally, the one-sided Riemann-based solid boundary condition is modified to handle the FSI coupling in both single-and multi-resolution scenarios in the triple point. A set of examples involving multi-phase flows with high density ratio, complex interface and multi-phase FSI are studied to demonstrate the efficiency, accuracy and robustness of the present method.

An Eulerian SPH method with WENO reconstruction for compressible and incompressible flows

While Eulerian smoothed particle hydrodynamics(SPH)method has received increasing attention in scientific and industrial communities owing to its high spatial accuracy,it exhibits excessive numerical dissipation due to the fact that the flux is derived in particle pair pattern.In this paper,we adopt a one-dimensional weighted essentially non-oscillatory(WENO)reconstruction to reduce the numerical dissipation and improve the overall accuracy particularly in capturing the contact discontinuity.The underlying principle is to construct a 4-point stencil along the interacting line of each particle pair and then the WENO scheme is applied to reconstruct the initial states of the Riemann problem which determines the flow flux.A set of benchmark tests for both compressible and incompressible flows are studied to investigate the accuracy,robustness and versatility of the proposed Eulerian SPH method with the WENO reconstruction(ESPH-WENO).

A CAD-compatible body-fitted particle generator for arbitrarily complex geo-metry and its application to wave-structure interaction

Generating body-fitted particle distribution for arbitrarily complex geometry underpins the applications of particle-based method to engineering and bioengineering and is highly challenging,and thus hinders the potential of particle methods.In this paper,we present a new computer-aided design(CAD)compatible body-fitted particle generator,termed as CAD-BPG,for arbitrarily complex 3-D geometry.By parsing a CAD model,the present method can accurately tackle arbitrarily complex geometry representation and describe the corresponding geometry surface by constructing an implicit zero level-set function on Cartesian background mesh.To achieve a body-fitted and isotropic particle distribution,physics-driven relaxation process with surface bounding governed by the transport-velocity formulation of smoothed particle hydrodynamics(SPH)methodology is conducted to characterize the particle evolution.A set of examples,ranging from propeller,stent structures and anatomical heart models,show simplicity,accuracy and versatility of the present CAD-BPG for generating body-fitted particle distribution of arbitrarily complex 3-D geometry.Last but not least,the present CAD-BPG is applied for modeling wave-structure interaction,where wave interaction with an oscillating wave surge converter is studied,and the results show that the present method not only provides an efficient and easy-to-implement pre-processing tool for particle-based simulation but also improves the numerical accuracy compared with lattice particle distribution.Consequently,the propose CAD-BPG sheds light on simulating real-world applications by particle-based methods for researchers and engineers.

SPH modeling of fluid-structure interaction

This work concerns numerical modeling of fluid-structure interaction（FSI） problems in a uniform smoothed particle hydrodynamics（SPH） framework. It combines a transport-velocity SPH scheme, advancing fluid motions, with a total Lagrangian SPH formulation dealing with the structure deformations. Since both fluid and solid governing equations are solved in SPH framework, while coupling becomes straightforward, the momentum conservation of the FSI system is satisfied strictly. A well-known FSI benchmark test case has been performed to validate the modeling and to demonstrate its potential.

Smoothed particle hydrodynamics:Methodology development and recent achievement

Since its inception,the full Lagrangian meshless smoothed particle hydrodynamics(SPH)has experienced a tremendous enhancement in methodology and impacted a range of multi-physics applications in science and engineering.This review presents a concise survey on latest developments and achievements of the SPH method,including:(1)Brief review of theory and fundamental with kernel corrections,(2)The Riemann-based SPH method with dissipation limiting and high-order data reconstruction by using MUSCL,WENO and MOOD schemes,(3)Particle neighbor searching with particle sorting and efficient dual-criteria time stepping schemes,(4)Total Lagrangian formulation with stablized,dynamics relaxation and hourglass control schemes,(5)Fluid-structure interaction scheme with interface treatments and multi-resolution discretizations,(6)Novel applications of particle relaxation in SPH methodology for mesh and particle generations.Last but not least,benchmark tests for validating computational accuracy,convergence,robustness and efficiency are also supplied accordingly.

Physics-Driven Learning of the Steady Navier-Stokes Equations using Deep Convolutional Neural Networks

Recently,physics-driven deep learning methods have shown particular promise for the prediction of physical fields,especially to reduce the dependency on large amounts of pre-computed training data.In this work,we target the physicsdriven learning of complex flow fields with high resolutions.We propose the use of Convolutional neural networks(CNN)based U-net architectures to efficiently represent and reconstruct the input and output fields,respectively.By introducingNavier-Stokes equations and boundary conditions into loss functions,the physics-driven CNN is designed to predict corresponding steady flow fields directly.In particular,this prevents many of the difficulties associated with approaches employing fully connected neural networks.Several numerical experiments are conducted to investigate the behavior of the CNN approach,and the results indicate that a first-order accuracy has been achieved.Specifically for the case of a flow around a cylinder,different flow regimes can be learned and the adhered“twin-vortices”are predicted correctly.The numerical results also show that the training for multiple cases is accelerated significantly,especially for the difficult cases at low Reynolds numbers,and when limited reference solutions are used as supplementary learning targets.

A Differentially Private Auction Mechanism in Online Social Networks

The growing popularity of users in online social network gives a big opportunity for online auction.The famous Information Diffusion Mechanism(IDM)is an excellent method even meet the incentive compatibility and individual rationality.Although the existing auction in online social network has considered the buyers’information which is not known by the seller,current mechanism still can not preserve the privacy information of users in online social network.In this paper,we propose a novel mechanism based on the IDM and differential privacy.Our mechanism can successfully process the auction and at the same time preserve clients’price information from neighbours.We achieved these by adding virtual nodes to each node and Laplace noise for its price in the auction process.We also formulate this mechanism on the real network and the random network,scale-free network to show the feasibility and effectiveness of the proposed mechanism.The evaluation shows that the result of our methods only depend on the noise added to the agents.It is independent from the agents’original price.

A microfluidic bleeding model to investigate the effects of blood flow shear on microvascular hemostasis

Hemorrhage is the phenomenon of blood loss caused by vascular trauma or other pathological reasons,which is life-threatening in severe cases.Because microhemorrhage is difficult to visually monitor and pre-treat in vivo,it is necessary to establish in vitro prediction methods to study the hemostasis mechanism in different physiological environments.In this study,a microfluidic bleeding model was developed to investigate the effect of blood flow shear on microvascular hemostasis.The results indicated that the regulation of blood shear rate on platelet aggregation affected the growth and morphology of hemostatic thrombus,and finally regulated the process of hemostasis.This in vitro model is significant to studies on hemostatic mechanisms,a reliable prediction of microhemorrhages,and an adjustment of the treatment scheme.