Can near-to-mid Infrared Spectral Energy Distribution Quantitatively Trace Protoplanetary Disk Evolution?

Infrared(IR)spectral energy distribution(SED)is the major tracer of protoplanetary disks.It was recently proposed to use the near-to-mid IR(or K-24)SED slopeαdefined between 2 and 24μm as a potential quantitative tracer of disk age.We critically examine the viability of this idea and confront it with additional statistics of IR luminosities and SED shapes.We point out that,because the statistical properties of most of the complicated physical factors involved in disk evolution are still poorly understood in a quantitative sense,the only viable way is to assume them to be random so that an idealized“average disk”can be defined,which allows theαhistogram to trace its age.We confirm that the statistics of the zeroth order(luminosity),first order(slopeα),and second order characteristics(concavity)of the observed K-24 SEDs indeed carry useful information upon the evolutionary processes of the“average disk”.We also stress that intrinsic diversities in K-24 SED shapes and luminosities are always large at the level of individual stars so that the application of the evolutionary path of the“average disk”to individual stars must be done with care.The data of most curves in plots are provided on GitHub(Disk-age package https://github.com/starage/disk-age/).

Probing the Kinematic Signatures of Planet Formation in the Gas Disk of MWC 480

The disk around MWC 480 has shown multiple substructures in both dust and gas observations,possibly suggesting ongoing planet formation in situ.In this paper,we explore the gas kinematics of the MWC 480 disk by analyzing the archival Atacama Large Millimeter/submillimeter Array observations of^(12)CO(J=2-1),^(13)CO(J=2-1),and C^(18)O(J=2-1).By modeling the line-of-sight velocities,inferred from the Doppler shifts of the emission lines,we are able to decompose the three-dimensional(3D)velocity field of the disk into rotational,radial,and vertical components.Further analysis reveals the presence of large-scale gas flows in the(r,z)plane.Notably,we identify potential meridional flows across various heights as traced by all three CO isotopologues in the 80–120 au region,possibly associated with ongoing planet formation activities in this region.Moreover,we find upward flows near 200 au for all three CO isotopologues,which may point to the presence of disk winds.

Photocatalytic ozonation-based degradation of phenol by ZnO—TiO_(2)nanocomposites in spinning disk reactor

Spinning disk reactor(SDR)has emerged as a novel process intensification photocatalytic reactor,and it has higher mass transfer efficiency and photon utilization for the degradation of toxic organic pollutants by advanced oxidation processes(AOPs).In this study,ZnO—TiO_(2)nanocomposites were prepared by solgel method,and coated on the disk of SDR by impregnation-pull-drying-calcination method.The performance of catalyst was characterized by X-ray diffraction,scanning electron microscope,X-ray photoelectron spectroscopy,photoluminescence and ultraviolet—visible diffuse reflectance spectroscopy.Photocatalytic ozonation in SDR was used to remove phenol,and various factors on degradation effect were studied in detail.The results showed that the rate of degradation and mineralization reached 100%and 83.4%under UV light irradiation after 50 min,compared with photocatalysis and ozonation,the removal rate increased by 69.3%and 34.7%,and mineralization rate increased by 56.7%and 62.9%,which indicated that the coupling of photocatalysis and ozonation had a synergistic effect.The radical capture experiments demonstrated that the active species such as photogenerated holes(h^(+)),hydroxyl radicals(·OH),superoxide radical(·O_(2)-)were responsible for phenol degradation,and·OH played a leading role in the degradation process,while h+and·O_(2)^(-)played a non-leading role.

Effects of multiple shapes for steady flow with transformer oil+Fe_(3)O_(4)+TiO_(2) between two stretchable rotating disks

In this study,we examine the effects of various shapes of nanoparticles in a steady flow of hybrid nanofluids between two stretchable rotating disks.The steady flow of hybrid nanofluids with transformer oil as the base fluid and Fe_(3)O_(4)+TiO_(2)as the hybrid nanofluid is considered.Several shapes of Fe_(3)O_(4)+TiO_(2)hybrid nanofluids,including sphere,brick,blade,cylinder,and platelet,are studied.Every shape exists in the same volume of a nanoparticle.The leading equations(partial differential equations(PDEs))are transformed to the nonlinear ordinary differential equations(ODEs)with the help of similarity transformations.The system of equations takes the form of ODEs depending on the boundary conditions,whose solutions are computed numerically by the bvp4c MATLAB solver.The outputs are compared with the previous findings,and an intriguing pattern is discovered,such that the tangential velocity is increased for the rotation parameter,while it is decreased by the stretching values because of the lower disk.For the reaction rate parameter,the concentration boundary layer becomes shorter,and the activation energy component increases the rate at which mass transfers come to the higher disk but have the opposite effect on the bottom disk.The ranges of various parameters taken into account are Pr=6.2,Re=2,M=1.0,φ_(1)=φ_(2)=0.03,K=0.5,S=-0.1,Br=0.3,Sc=2.0,α_(1)=0.2,γ=0.1,E_(n)=2.0,and q=1.0,and the rotation factor K is within the range of 0 to 1.

An Asymmetric Galactic Stellar Disk Traced by OB-type Stars from LAMOST DR7

Using 9943 OB-type stars from LAMOST DR7 in the solar neighborhood,we fit the vertical stellar density profile with the model including a single exponential distribution at different positions(R,Φ).The distributions of the scale heights and scale length show that the young disk traced by the OB-type stars is not axisymmetric.The scale length decreases versus the azimuthal angleΦ,i.e.,from.■kpc withΦ=-3°to■kpc withΦ=9°.Meanwhile we find signal of non-symmetry in the distribution of the scale height of the north and south of the disk plane.The scale height in the north side shows signal of flaring of the disk,while that of the south disk stays almost constant around h_(s)=130 pc.The distribution of the displaceeent of the disk plane Z_(0)also shows variance versus the azimuthal angleΦ,which displays significant differences with the warp model constrained by the Cepheid stars.We also test different values for the position of the Sun,and the distance between the Sun and the Galactic center affects the scale heights and the displacement of the disk significantly,but that does not change our conclusion that the disk is not axisymmetric.

Analyzing Thermal Stratification and Nanoparticle Shapes Influence on an EMHD Ternary Nanofluid Flow amidst Two Spinning Disks

The present study examines the thermal distribution of ternary nanofluid flow amid two spinning disks influenced by electric and magnetic fields. Keeping in view the shape of the particles, the electrically conducting ternary nanofluid is analyzed with variable thermophysical features. Three types of nanoparticles namely Copper, Aluminum Oxide, and Graphene with spherical, cylindrical, and platelet shapes are taken respectively and are immersed in a (50-50)% ratio of water and ethylene glycol mixture which acts as a base fluid. The anticipated problem is addressed by employing a reliable and user-friendly numerical bvp4c built-in collocation scheme. This solution is then showcased through illustrations and tables. Strengthening the radiation results in an enhanced heat transfer rate. Radial and azimuthal velocities once rotation of disks is enhanced. The key findings provide a strong theoretical background in photovoltaic cells, solar collectors, radiators, solar water heaters, and many other applications.

基于Hot Disk方法测量热导率的影响因素

基于hot disk方法测量材料的热导率时,探头热容及时间延迟的存在会直接影响热导率测量的准确度.为了有效地评估这种影响的程度,本文基于探头表面平均温升理想模型提出了一种可实现热容补偿及时间补偿的修正模型,并利用hot disk热物性分析仪的数据采集系统分别搭载两个不同半径的探头对Pyroceram 9606标准材料在常温常压条件下的热导率进行了测量.实验结果表明,对于测试时间比较短的情况,对理想模型进行探头热容补偿及时间补偿能够较大幅度地提高热导率的测量准确度,并且与hot disk热物性分析仪的测量结果非常接近,探头四线电阻散热的影响是造成差距的主要原因.

二极管泵浦Yb:YAG Thin Disk激光器光束质量及V型腔腔内倍频的研究

Thin Disk激光器由于其独特的设计可以同时获得高转换效率和光束质量。对Yb:YAG Thin Disk激光器中泵浦光斑与腔模的耦合对光束质量的影响作了分析,并在普通直腔和V型腔的实验中分别获得M^2=1.15,13.69W和M^2=1.12,13.85W的1030nm激光输出,还在V型腔中进行了腔内倍频的实验研究。

Thermal analysis for brake disks of SiC/6061 Al alloy co-continuous composite for CRH3 during emergency braking considering airflow cooling

The mass of high-speed trains can be reduced using the brake disk prepared with SiC network ceramic frame reinforced 6061 aluminum alloy composite （SiCn/Al）. The thermal and stress analyses of SiCn/Al brake disk during emergency braking at a speed of 300 km/h considering airflow cooling were investigated using finite element （FE） and computational fluid dynamics （CFD） methods. All three modes of heat transfer （conduction, convection and radiation） were analyzed along with the design features of the brake assembly and their interfaces. The results suggested that the higher convection coefficients achieved with airflow cooling will not only reduce the maximum temperature in the braking but also reduce the thermal gradients, since heat will be removed faster from hotter parts of the disk. Airflow cooling should be effective to reduce the risk of hot spot formation and disc thermal distortion. The highest temperature after emergency braking was 461 °C and 359 °C without and with considering airflow cooling, respectively. The equivalent stress could reach 269 MPa and 164 MPa without and with considering airflow cooling, respectively. However, the maximum surface stress may exceed the material yield strength during an emergency braking, which may cause a plastic damage accumulation in a brake disk without cooling. The simulation results are consistent with the experimental results well.

Analysis of high-power disk laser welding stability based on classification of plume and spatter characteristics

Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Characteristic parameters such as the area and number of spatters, the average grayscale of a spatter image, the entropy of a spatter grayscale image, the coordinate ratio of the plume centroid and the welding point, the polar coordinates of the plume centroid were defined and extracted. Karhunen-Loeve transform method was used to change the seven characteristics into three primary characteristics to reduce the dimensions. Also, K-nearest neighbor method was used to classify the plume and spatter images into two categories such as good and poor welding quality. The results show that plume and spatter have a close relationship with the welding stability, and two categories could be recognized effectively using K-nearest neighbor method based on Karhunen-Loeve transform.

Analytical Solution for Laminar Viscous Flow inthe Gap Between Two Parallel Rotary Disks

Aim To get the analytical for laminar viscous flow in the gap of two parallel rotating disks. Methods By estimating the order of magnitude of each term in the Navier-Stokes equations to drop small terms and achieve the required simplified differential equations, and by integrating the equations to obtain the solution for theflow between two rotary disks. Results Parameters related to the laminar viscous flow in the gap between two parallel rotary disks, such as the velocity, the pressure, the flowrate, the force, the shearing stress, the torque and the power derived. Conclusion The result provides a theoretical basis and an effective method for the designs of the devices connected with the laminar viscous flow in the gap between two parallel rotary disks.

二极管泵浦Yb:YAG Thin Disk激光器获得16 W连续激光输出

近年来，Ｙｂ：ＹＡＧ激光研究已被视为发展高效、高功率二极管泵浦固体激光器的一个主要方向．本文简要分析了 Ｙｂ ＹＡＧ作为增益介质优于 Ｎｄ ＹＡＧ的性质，阐述Ｔｈｉｎ Ｄｉｓｋ激光器的原理，并介绍了我们在国内首次获得 １６ Ｗ连续激光（波长 １０３０ ｎｍ）输出的二极管泵浦 Ｙｂ：ＹＡＧ Ｔｈｉｎ Ｄｉｓｋ激光器装置及数据．

基于Hot-disk的液体导热系数测量装置实验研究

基于Hot-disk热物性分析仪,开发了一种应用于液体导热系数测定的装置。应用该装置对液体进行导热系数测定时,可以较好地避免自然对流的影响,且制作简便,成本低廉。使用该装置对26℃的去离子水进行了5次测量,并分析了其测量结果。最大测量误差为8.5%,最小测量误差为2.05%,测量误差平均值为5.84%,5次测试的结果平均值为0.573 1 W/m·K,与文献标准值的偏差仅为3.72%。测试精确度较公式法取得很大进步,可以满足工程应用。

使用Broadcast Disks方法分布的空中位图索引

提出一种使用BroadcastDisks算法来分布位图索引的空中索引方法,根据数据项访问概率,使用位图作为数据广播的索引,减少了移动终端等待数据时保持激活状态的时间,达到节能的目的。

基于Linux平台下的Web Disk软件系统开发

主要论述了在Linux平台下整个Webdisk软件系统的开发方法。Webdisk系统是基于浏览器的管理 ,主要提供文件的网络存储服务。同时本系统还提供功能强大的用户管理服务和比较完善的系统管理服务 ,它们不仅为用户在使用本系统时提供方便 。

Hot disk探头热容对热导率测量的影响

Hot disk探头热容的存在会直接影响热导率测量的准确度。为有效地评估这种影响的程度,在基于瞬态点热源格林函数法得到探头表面平均温升理想模型的基础上,提出了一种能够修正探头热容对实际加热功率影响的改进模型,并利用三种不同大小及热容值的探头及Hot disk数据采集系统对Pyroceram 9606标准材料的热导率进行了测量。测量结果表明,Hot disk探头热容对热导率测量精度的影响会随探头半径、测量时间及加热功率等测量参数的不同而发生变化,对理想模型进行探头热容补偿可以有效提高热导率测量准确度,且探头热容相对实验总加热量的大小是影响热导率测量准确度的决定因素。

Dynamic Characteristics of Ultra Thin Liquid Lubricated Head-Disk Assembly in Magnetic Hard Disk Files

The dynamic characteristics of a liquid thin film lubricated head disk system are analyzed. The shear thinning effect is taken into account by introducing modification coefficients into the lubricant rheological model. The perturbation theory is employed to set up the dynamic pressure equation. The Reynolds equation and dynamic pressure equations are solved by finite difference method. The results obtained by the difference methods agree well with that calculated by the close solutions. IBM3370 slider is employed as a physical model. The slider of the system can keep flying at 20 nm height, which promises a potential application on high density recording device.

用Disk Manager2000管理和维护大容量硬盘

详细介绍了利用 Disk Manager2000对新硬盘进行安装及安装中盘符交错的问题。安装后如何对硬盘进行维护、分区等。其中介绍了重新分区、正确定位光驱盘符、不同盘之间的文件拷贝,以及怎样创建 For Dos 的启动盘。同时介绍了硬盘检测工具 Run SmartedFender 使用方法。

磁盘——DISK与光碟——DISC 关于CDCD-DAVCDDVD等名词汉语定名的建议

全国科学技术名词审定委员会正在组织审定一部分多媒体技术方面的新词 (其征求意见稿已在本刊 99— 2期上刊载 )。审定中对个别名词存在分歧 ,例如信息技术中的常见词“盘”和“碟”。是区分 ,还是统一 ,分歧较大。现将部分有代表性的意见刊出 ,供大家讨论 ,以便尽快订出比较科学合理的规范名。

基于Hot Disk测定食用油的导热系数的研究

食用油是日常的饮食和现代食品工业不可或缺的重要物质,具有较高的营养价值。油脂精炼工序中脱胶、脱酸、脱色、脱臭、脱蜡(脂)等工序中的设备则需要根据所加工油脂的导热系数进行设备选型[1]。本实验根据瞬变平面热源法(Transient Plane Source,TPS)的测量原理[2],使用Hot Disk热常数分析仪测量葵花籽油、玉米胚芽油在不同加热功率、测量时间和温度时的导热系数,选择最优化的实验参数方案,研究加热功率、测量时间、温度对导热系数的影响[3]。