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/).

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.

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.

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.

Transition from isotropic to polar state of self-driven eccentric disks

Inspired by the eccentricity design of self-driven disks,we propose a computational model to study the remarkable behavior of this kind of active matter via Langevin dynamics simulations.We pay attention to the effect of rotational friction coefficient and rotational noise on the phase behavior.A homogeneous system without rotational noise exhibits a sharp discontinuous transition of orientational order from an isotropic to a polar state with the increase of rotational friction coefficient.When there is rotational noise,the transition becomes continuous.The formation of polar state originates from the effective alignment effect due to the mutual coupling of the positional and orientational degrees of freedom of each disk.The rotational noise could weaken the alignment effect and cause the large spatial density inhomogeneity,while the translational noise homogenizes the system.Our model makes further conceptual progress on how the microscopic interaction among self-driven agents yields effective alignment.

Analysis of stresses at the center of transversely isotropic Brazilian disk

This article presents the stresses at the center of a Brazilian disk(BD)for transversely isotropic rocks.It is shown that the solution of stresses at the center of an anisotropic disk is a function of the disk radius and the magnitude of applied load,as well as the material orientation with respect to the load axis and two dimensionless ratios with specific physical meanings and limitations.These two dimensionless parameters are the ratios of Young’s modulus and apparent shear modulus,although the ratio of apparent shear modulus will be eliminated if the Saint-Venant assumption is considered.Considerable finite element simulations are carried out to find the stresses at the disk center concerning the material orientation and the two dimensionless parameters.Also,an approximate formula obtained from analytical results,previously proposed in the literature for solving the tensile and compressive stresses at the disk center,is re-written and simplified based on these new definitions.The results of the approximate formula fitted to the analytical results are compared to those obtained from numerical solutions,suggesting a good agreement between the numerical and analytical methods.An approximate equation for the shear stress at the disk center is also formulated based on the numerical results.Finally,the influence of the assumptions for simplification of the proposed formula for the tensile,compressive,and shear stresses at the disk center is discussed,and simple and practical equations are proposed as estimations for the stresses at the center of the BD specimen for low to moderate anisotropic rocks.For highly anisotropic rocks,the reference plots can be used for more accuracy.

The Spin Measurement of MAXI J0637-430:a Black Hole Candidate with High Disk Density

The Galactic black hole candidate MAXI J0637-430 was first discovered by MAXI/GSC on 2019 November 2.We study the spectral properties of MAXI J0637-430 by using the archived NuSTAR data and Swift/XRT data.After fitting the eight spectra by using a disk component and a powerlaw component model with absorption,we select the spectra with relatively strong reflection components for detailed X-ray reflection spectroscopy.Using the most state-of-art reflection model,relxillCp,the spectral fitting measures a black hole spin a_(*)>0.72 and the inclination angle of the accretion disk i=46.1_(-5.3)^(+4.0)degrees,at a 90%confidence level.In addition,the fitting results show an extreme supersolar iron abundance.Combined with the fitting results of reflection model reflionx_hd,we consider that this unphysical iron abundance may be caused by a very high-density accretion disk(n_(e)>2.34×10^(21)cm^(-3))or a strong Fe K_(α) emission line.The soft excess is found in the soft state spectral fitting results,which may be an extra free-free heating effect caused by high density of the accretion disk.Finally,we discuss the robustness of black hole spin obtained by X-ray reflection spectroscopy.The result of relatively high spin is self-consistent with broadened Fe K_(α) line.Iron abundance and disk density have no effect on the spin results.

Finite deformation analysis of the rotating cylindrical hollow disk composed of functionally-graded incompressible hyper-elastic material

The deformations and stresses of a rotating cylindrical hollow disk made of incompressible functionally-graded hyper-elastic material are theoretically analyzed based on the finite elasticity theory.The hyper-elastic material is described by a new micro-macro transition model.Specially,the material shear modulus and density are assumed to be a function with a power law form through the radial direction,while the material inhomogeneity is thus reflected on the power index m.The integral forms of the stretches and stress components are obtained.With the obtained complicated integral forms,the composite trapezoidal rule is utilized to derive the analytical solutions,and the explicit solutions for both the stretches and the stress components are numerically obtained.By comparing the results with two classic models,the superiority of the model in our work is demonstrated.Then,the distributions of the stretches and normalized stress components are discussed in detail under the effects of m.The results indicate that the material inhomogeneity and the rotating angular velocity have significant effects on the distributions of the normalized radial and hoop stress components and the stretches.We believe that by appropriately choosing the material inhomogeneity and configuration parameters,the functionally-graded material(FGM)hyper-elastic hollow cylindrical disk can be designed to meet some unique requirements in the application fields,e.g.,soft robotics,medical devices,and conventional aerospace and mechanical industries.

Evaluation of Disk Potentiation Test (DPT) and Double Disk Synergy Test (DDST) for The Detection of Metallo-β-Lactamases (MBLs) in Clinical Isolates of Bangladesh

Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determine a suitable method to promptly detect MBL-producing gram-negative bacteria. Methods: A total of 103 gram-negative bacteria were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods, the Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on β-lactam chelator combinations where EDTA/SMA has been used as an inhibitor and Imipenem, Ceftazidime as substrates. Results: 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. Isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8 (7.8%), Proteus spp 1 (1%) and Providencia spp 1 (1%). DPT method detected significantly (p = 0.000009) a higher number of MBL-producers (Imipenem with 0.5 M EDTA n = 61, 59.2% & Ceftazidime with 0.5 M EDTA n = 56, 54.4%) compared to the DDST method (Imipenem -0.5 M EDTA n = 43, 41.7%, Imipenem – SMA n = 38, 36.9% & Ceftazidime -0.5 M EDTA n = 15, 14.6%). Conclusion: Pieces of evidence suggest that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, to reduce time constraints and treatment costs.

水中旋转圆盘振动阻尼测量与模拟

为了研究模态做功法在计算旋转式机械水力阻尼时的适用性和准确性,利用旋转圆盘阻尼测量系统的实验数据对该方法做了评估.研究表明,圆盘的水力阻尼值随转速的增加呈现下降的趋势;利用模态做功法计算水力阻尼值时必须考虑旋转效应带来的影响,如果直接使用静止条件下的模态结果,水力阻尼随转速的变化规律将完全和实验结果相反;在考虑旋转的条件下,计算精度有所提高,但整体呈现过预测的问题,该方法对旋转结构阻尼特性的预测精度还有待提高.

高速水洞中超空泡稳定性与通气率定量试验研究

超空泡航行体通气规律对空泡形态控制具有重要意义。本文描述了在高速水洞中建立水下航行体通气率对超空泡形态及稳定性影响的一种试验研究方法。基于不同空化器和模型攻角条件下的空泡形态及通气率测量试验结果,总结得到无量纲通气率计算的经验表达式。通过对有、无尾翼条件下的通气率试验进行比较,初步获得尾翼对超空泡泄气的影响规律。研究结果表明,通气率需要保持在一定范围内方可获得形状稳定、边界清晰的通气超空泡。依据试验结果给出了超空泡稳定性的判别方法。

双磁盘磁力钝化机制及实验研究

对刀具刃口进行钝化可以显著的提高刀具寿命,为了探究磁力钝化技术对刀具刃口的影响。首先,设计并搭建了双磁盘磁力钝化设备,分析了双磁盘磁力钝化的基本原理及单元磨粒的受力;然后,通过对陶瓷、PCD金刚石以及硬质合金刀具进行磁力钝化实验,并基于B样条曲线对刃口进行表征,通过刃口的磨损量探究了不同刀具材料对磁力钝化的影响;最后,通过设置正交试验,采用响应面法和极差法分析了磁盘转速、刀具转速、磁盘间距、钝化时间对硬质合金刀具在双磁盘磁力钝化中的影响规律。实验发现,材料的相对磁导率对钝化磨损量的影响较大,磁盘转速与刀具转速并非线性关系,钝化磨损量随钝化时间呈递增关系,且最优组合为:磁盘转速200r/min、刀具转速45r/min、磁盘间距为15mm、钝化时间为12min。

基于自适应聚类和线性规划最优选点的彩色图像低成本打印方法

彩色点画是一种从视觉上由大量小像素点构建图像的艺术技术,像素个数的多少直接影响着构图的成本。其优化选点构图方法为实现低成本打印提供了一个重要的方式。目前,点画生成存在着多通道采样点难以均匀分布,颜色层次难以兼顾等难点,并耗费大量的计算成本。对此,提出了一种基于超像素自适应聚类和线性规划最优选点的彩色点画生成方法,该方法在初步超像素划分图像的基础上,使用基于颜色密度峰值的自适应聚类方法得到最佳聚类个数,并进一步划分子聚类,然后根据每个子聚类的颜色均值作为子聚类内部选点的最佳间隔距离,在选点的同时依据SSIM指标,建立目标优化模型,通过数学优化器Gurobi实现模型选点,使点保留最少个数的目标基础上,同时保持聚类内部分布均匀和颜色渐变层次,以提高所生成的点画图像的可视化效果。实验结果表明,本文算法极大地降低了像素个数并在生成的点画的平均结构相似性(mean structural similarity index measure,SSIM)、峰值信噪比(peak signal to noise ratio,PSNR)等评价指标方面均优于当前方法。

1ZL-7.2型联合整地机的研制

整地作业可将犁耕后的土壤进行碎土、平整,为播种环节创造良好的作业条件,联合整地机在新疆已被广泛应用。近年来大中马力拖拉机保有量逐年增加,为提高整地作业幅宽和效率,研制了一款与大马力拖拉机相配套的联合作业机,开发了新型合金材料的耐磨耙片。作业幅宽为7.2 m,机架可以进行折叠便于运输。田间试验表明,该型机具作业效果良好,故障率低,操作简单、方便。

吡罗昔康贴剂溶出度的测定及不同测定方法结果的评估

目的:采用桨碟法、转筒法、扩散池法测定吡罗昔康贴剂的溶出度,并对溶出结果进行评价,以期选择能更加准确反映吡罗昔康贴剂释药过程的测定方法,为科学准确评价药品质量提供参考。方法:建立检测吡罗昔康的液相色谱测定方法,分别使用桨碟法、转筒法、扩散池法考察吡罗昔康贴剂的24 h溶出曲线,分别使用f 1差异因子法、f 2相似因子法、Weibull模型拟合对溶出曲线进行比较,评估不同测定方法的结果。结果:吡罗昔康在1~150μg·mL^(-1)范围内线性关系良好(r=1.000),准确度100.9%(n=9),精密度1.7%(n=9),样品溶液在72 h内稳定。溶出曲线比较结果表明,吡罗昔康贴剂的溶出曲线更符合Weibull模型。在相同溶出介质和温度的条件下,桨碟法和转筒法差异不大,存在相互替代的可能性,扩散池法与其他2种方法均存在显著性差异。结论:扩散池法的装置更加符合吡罗昔康贴剂在实际使用中的溶出过程,为该药物的质量评价提供更多的参考。

基于LIBS数据流盘的飞机蒙皮激光除漆在线监测判据研究

等离子体产生及演化过程易受基体效应、环境噪声、脉冲能量抖动等影响,导致光谱数据具有不稳定性,从而难以保证以单条谱线为依据建立的监测判据的有效性。以连续多幅LIBS光谱为对象,并结合统计学方法建立的监测判据,可有效提升基于LIBS技术的除漆效果监测精度。论文基于搭建的高频纳秒红外脉冲激光除漆LIBS在线监测平台,实时采集了除漆过程的连续多幅LIBS光谱。光谱数据经基线矫正、归一化预处理后,依据面漆、底漆、铝合金基体光谱特征峰差异,并结合材料成分信息,选定BaⅠ(712.55 nm)、CrⅠ(357.48 nm)、CrⅠ(425.43 nm)、TiⅠ(427.45 nm)、CuⅡ(309.76 nm)、CuⅠ(484.22 nm)6条谱线作为特征谱线并监测除漆效果。研究不同除漆效果中6条特征谱线强度变化规律,建立不同除漆效果与所选特征谱线强度变化区间的映射关系。提取每幅谱线的上述6条特征谱线强度作为一组数据单元、将连续10幅谱线的数据单元作为一组数据集,除漆过程中随时间变化的每10组迭代数据集称为数据流盘。对数据流盘中的数据单元、数据集进行分析,结合置信区间,实时判定除漆区域除漆效果,获得基于数据流盘的监测判据。结果表明:该判据可有效监测仍在面漆、面漆完全去除、仍在底漆、底漆完全去除、基体损伤5类除漆效果。依据SRM手册对漆层去除效果的要求,选择面漆完全去除、基体损伤两类除漆效果展示了验证过程,三维微观形貌分析结果与LIBS数据流盘监测判据所得除漆效果结论一致。其中,面漆去除后三维微观形貌分析表明,面漆完全去除精度达1.2μm,有效验证了基于LIBS数据流盘监测判据的适用性及稳定性。

一种融合注意力机制的CNN-BiGRU磁盘故障预测方法研究

磁盘作为重要的存储介质,一旦出现故障很可能会导致存储数据丢失,给个人及企业带来难以估量的损失。现有磁盘故障预测模型存在不能很好地平衡磁盘数据样本、未充分利用磁盘数据的时序特性等问题。以Backblaze云存储公司公布的真实磁盘数据为研究对象,提出了一种融合注意力机制的卷积神经网络(CNN)和双向门控循环单元(BiGRU)网络的磁盘故障预测模型。在数据预处理方面,采用负采样与焦点损失函数来平衡正负样本,利用CNN进行特征提取,并结合BiGRU网络来有效地处理时序数据。通过融合注意力机制,能够让模型快速地捕捉更多关键特征信息,将筛选出的特征与数据输入模型进行训练。通过对比其他故障预测模型,本文提出的模型在精确率等4个评价指标上均有1%~7%的性能提升,为提高磁盘存储的可靠性提供了有力的支撑。

浸入运动边界-格子Boltzmann方法4种固含率计算方法对比研究

为了达到流固耦合,格子Boltzmann方法(LBM)可采用浸入运动边界法(IMB)实现移动颗粒边界上的无滑移条件.该耦合方式(IMB-LBM)中固含率计算方法对流固耦合计算精度和效率有影响.对常用的固含率4种计算方法,即蒙特卡洛法(MCM)、单元分解法(UDM)、近似多边形法(APM)和闭合边界法(CBM),分别阐述其具体算法,对比了它们的计算精度和计算效率;最后通过圆盘颗粒非连续变形分析方法(DDDA)与IMB-LBM耦合模型下的一个多颗粒沉降流固耦合算例,对比分析了它们在流固耦合计算过程中的耗时.结果表明:1)CBM无误差,MCM和UDM在随机点数取1000,子单元数取100时误差稳定在1%以下,APM在颗粒直径大于格子长度10倍时,误差小于0.44%;2)MCM和UDM的计算精度及耗时分别与随机点数和子单元数相关,它们的计算耗时大于APM和CBM;3)计算效率上,APM>CBM>UDM>MCM,其中CBM计算耗时略微大于APM,APM和UDM计算耗时分别比MCM少2个和1个数量级.该结果可为IMB-LBM耦合模型中固含率计算方法优选提供借鉴.