The Jiao Tong University Spectroscopic Telescope Project

The Jiao Tong University Spectroscopic Telescope(JUST)is a 4.4-meter f/6.0 segmented-mirror telescope dedicated to spectroscopic observations.The JUST primary mirror is composed of 18 hexagonal segments,each with a diameter of 1.1 m.JUST provides two Nasmyth platforms for placing science instruments.One Nasmyth focus fits a field of view of 10′and the other has an extended field of view of 1.2°with correction optics.A tertiary mirror is used to switch between the two Nasmyth foci.JUST will be installed at a site at Lenghu in Qinghai Province,China,and will conduct spectroscopic observations with three types of instruments to explore the dark universe,trace the dynamic universe,and search for exoplanets:(1)a multi-fiber(2000 fibers)medium-resolution spectrometer(R=4000-5000)to spectroscopically map galaxies and large-scale structure;(2)an integral field unit(IFU)array of 500 optical fibers and/or a long-slit spectrograph dedicated to fast follow-ups of transient sources for multi-messenger astronomy;(3)a high-resolution spectrometer(R~100000)designed to identify Jupiter analogs and Earth-like planets,with the capability to characterize the atmospheres of hot exoplanets.

Efflcient machining of a complex blisk channel using a disc cutter

For rough machining of a complex narrow cavity,e.g.,a complex blisk channel on an aero-engine,the typically used cutting tools are the slender cylindrical cutter and conical cutter.Nevertheless,as neither of the two is particularly suited for rough machining,wherein the main purpose is to remove a large volume as quickly as possible,the machining efficiency is low,especially when the part materials are of hard-to-cut types(e.g.,Titanium-alloy)for which it often takes days to rough machine a blisk.Fortunately,disc machining provides a new and efficient roughing solution,since a disc cutter with a large radius enables a much larger cutting speed and thus a larger material removal rate.However,due to the large radius of the disc cutter,its potential collision with narrow and twisted channels becomes a serious concern.In this paper,we propose a novel twophase approach for efficiently machining a complex narrow cavity workpiece using a disc-shaped cutter,i.e.,3+2-axis disc-slotting of the channel by multiple layers(rough machining)+five-axis disc-milling of the freeform channel side surfaces(semi-finish machining).Both simulation and physical cutting experiments are conducted to assess the effectiveness and advantages of the proposed method.The experimental results show that,with respect to a same cusp-height threshold on the channel side surfaces,the total machining time of the tested part by the proposed method is about only 36%of that by the conventional approach of plunging-milling(for roughing)plus milling by a slender cylindrical cutter(for semi-finishing).

Human-pose estimation based on weak supervision

Background In computer vision,simultaneously estimating human pose,shape,and clothing is a practical issue in real life,but remains a challenging task owing to the variety of clothing,complexity of de-formation,shortage of large-scale datasets,and difficulty in estimating clothing style.Methods We propose a multistage weakly supervised method that makes full use of data with less labeled information for learning to estimate human body shape,pose,and clothing deformation.In the first stage,the SMPL human-body model parameters were regressed using the multi-view 2D key points of the human body.Using multi-view information as weakly supervised information can avoid the deep ambiguity problem of a single view,obtain a more accurate human posture,and access supervisory information easily.In the second stage,clothing is represented by a PCA-based model that uses two-dimensional key points of clothing as supervised information to regress the parameters.In the third stage,we predefine an embedding graph for each type of clothing to describe the deformation.Then,the mask information of the clothing is used to further adjust the deformation of the clothing.To facilitate training,we constructed a multi-view synthetic dataset that included BCNet and SURREAL.Results The Experiments show that the accuracy of our method reaches the same level as that of SOTA methods using strong supervision information while only using weakly supervised information.Because this study uses only weakly supervised information,which is much easier to obtain,it has the advantage of utilizing existing data as training data.Experiments on the DeepFashion2 dataset show that our method can make full use of the existing weak supervision information for fine-tuning on a dataset with little supervision information,compared with the strong supervision information that cannot be trained or adjusted owing to the lack of exact annotation information.Conclusions Our weak supervision method can accurately estimate human body size,pose,and several common types of clothing and overcome the issues of the current shortage of clothing data.

Activation of AMPKα1 is essential for regulatory T cell function and autoimmune liver disease prevention

Regulatory T cells(Treg cells)are crucial for maintaining immune tolerance.Compromising the regulatory function of Treg cells can lead to autoimmune liver disease.However,how Treg cell function is regulated has not been fully clarified.Here,we report that mice with AMP-activated protein kinase alpha 1(AMPKα1)globally knocked out spontaneously develop immune-mediated liver injury,with massive lymphocyte infiltration in the liver,elevated serum alanine aminotransferase levels,and greater production of autoantibodies.Both transplantation of wild-type bone marrow and adoptive transfer of wild-type Treg cells can prevent liver injury in AMPKα1-KO mice.In addition,Treg cell-specific AMPKα1-KO mice display histological features similar to those associated with autoimmune liver disease,greater production of autoantibodies,and hyperactivation of CD4^(+)T cells.AMPKα1 deficiency significantly impairs Treg cell suppressive function but does not affect Treg cell differentiation or proliferation.Furthermore,AMPK is activated upon T cell receptor(TCR)stimulation,which triggers Foxp3 phosphorylation,suppressing Foxp3 ubiquitination and proteasomal degradation.Importantly,the frequency of Treg cells and the phosphorylation levels of AMPK at T172 in circulating blood are significantly lower in patients with autoimmune liver diseases.Conclusion:Our data suggest that AMPK maintains the immunosuppressive function of Treg cells and confers protection against autoimmune liver disease.

不同坡度对汽车机械厂房作用下的振动响应

本文通过实地三向测试来分析不同边坡对汽车机械厂房的振动响应,并用于验证模型的准确性。采用abaqus隐式动力有限元单元法建立边坡模型,研究了不同的坡度对于机械厂房的振动影响。以速度RMS作为响应标准,计算了不同坡度条件下的振动响应。在此基础上提取了模型部分监测点的频谱曲线,揭示了坡度对于单体边坡振动响应的定量作用规律。数值结果表明:在X和Y方向上,随着坡度增加到30˚时,从速度RMS上看有放大效应,应尽量避免;坡度增加到50˚时,X方向速度RMS最小,坡度增加到70˚时,Y和Z方向上最小;坡度由70˚继续增加至90˚时,三个方向的速度RMS都有所增加,Z方向上最明显,说明直角坡从减振效果不是最好选择。

Efficient cutting path planning for a non-spherical tool based on an iso-scallop height distance field

Iso-scallop height machining means,when machining a freeform surface,the scallop height between any two neighboring tool paths on the surface will be a constant(i.e.,the given threshold),which is preferable among various freeform surface machining strategies due to its high machining efficiency as well as better machine tool’s dynamics.However,all the existing iso-scallop height path planning methods pertain to only the ball-end or flat-end types of tools.In recent years,the non-spherical cutting tool has become more and more popular,especially for five-axis machining of complex freeform surfaces,majorly owing to its non-constant curvature which can be utilized to adaptively fit the tool to the surface to both avoid the local gouging and enlarge the cutting width.However,there have been no reported works on iso-scallop height five-axis tool path generation for a non-spherical tool,and,in this paper,we present one.Specifically,we first define and construct two fields on the surface to be machined-the collision-free tool orientation field(vector)and the iso-scallop height distance field(scalar).The iso-lines of the scalar field and their associated tool orientation field vectors then naturally serve as potential iso-scallop height five-axis tool paths,and we present a propagation-based algorithm to construct the desired tool path from the iso-lines.The computer simulation and physical cutting experiments confirm that everywhere on the surface,except maybe near the saddle curves of the scalar filed,the scallop height is exactly the given thresh-old.By adding the saddle curves as extra tool paths,the final machined surface then is assured of the required scallop height requirement.

Improving constraint onΩ_(m)from SDSS using marked correlation functions

Large-scale structure(LSS)surveys will increasingly provide stringent constraints on our cosmological models.Recently,the density-marked correlation function(MCF)has been introduced,offering an easily computable density-correlation statistic.Simulations have demonstrated that MCFs offer additional,independent constraints on cosmological models beyond the standard two-point correlation(2PCF).In this study,we apply MCFs for the first time to SDSS CMASS data,aiming to investigate the statistical information regarding clustering and anisotropy properties in the Universe and assess the performance of various weighting schemes in MCFs,and finally obtain constraints onΩ_(m).Upon analyzing the CMASS data,we observe that,by combining different weights(α=[-0.2,0,0.2,0.6]),the MCFs provide a tight and independent constraint on the cosmological parameterΩ_(m),yieldingΩ_(m)=0.293±0.006 at the 1σlevel,which represents a significant reduction in the statistical error by a factor of 3.4 compared to that from 2PCF.Our constraint is consistent with recent findings from the small-scale clustering of BOSS galaxies(Zhai et al.Astronphys.J.948,99(2023))within the 1σlevel.However,we also find that our estimate is lower than the Planck measurements by about 2.6σ,indicating the potential presence of new physics beyond the standard cosmological model if all the systematics are fully corrected.The method outlined in this study can be extended to other surveys and datasets,allowing for the constraint of other cosmological parameters.Additionally,it serves as a valuable tool for forthcoming emulator analysis on the Chinese Space Station Telescope(CSST).

A shear-thinning,ROS-scavenging hydrogel combined with dental pulp stem cells promotes spinal cord repair by inhibiting ferroptosis

Spinal cord injury(SCI)is a serious clinical disease.Due to the deformability and fragility of the spinal cord,overly rigid hydrogels cannot be used to treat SCI.Hence,we used TPA and Laponite to develop a hydrogel with shear-thinning ability.This hydrogel exhibits good deformation,allowing it to match the physical properties of the spinal cord;additionally,this hydrogel scavenges ROS well,allowing it to inhibit the lipid peroxidation caused by ferroptosis.According to the in vivo studies,the TPA@Laponite hydrogel could synergistically inhibit ferroptosis by improving vascular function and regulating iron metabolism.In addition,dental pulp stem cells(DPSCs)were introduced into the TPA@Laponite hydrogel to regulate the ratios of excitatory and inhibitory synapses.It was shown that this combination biomaterial effectively reduced muscle spasms and promoted recovery from SCI.

Miura-ori structured flexible microneedle array electrode for biosignal recording

Highly reliable signal recording with low electrode-skin impedance makes the microneedle array electrode(MAE)a promising candidate for biosignal sensing.However,when used in long-term health monitoring for some incidental diseases,flexible microneedles with perfectly skin-tight fit substrates lead to sweat accumulation inside,which will not only affect the signal output but also trigger some skin allergic reactions.In this paper,a flexible MAE on a Miura-ori structured substrate is proposed and fabricated with two-directional in-plane bendability.The results from the comparison tests show enhanced performance in terms of(1)the device reliability by resisting peeling off of the metal layer from the substrate during the operation and(2)air ventilation,achieved from the air-circulating channels,to remove sweat.Bio-signal recordings of electrocardiography(ECG),as well as electromyography(EMG)of the biceps brachii,in both static and dynamic states,are successfully demonstrated with superior accuracy and long-term stability,demonstrating the great potential in health monitoring applications.