A unified Minorization-Maximization approach for estimation of general mixture models

The mixed distribution model is often used to extract information from heteroge-neous data and perform modeling analysis.When the density function of mixed distribution is complicated or the variable dimension is high,it usually brings challenges to the parameter es-timation of the mixed distribution model.The application of MM algorithm can avoid complex expectation calculations,and can also solve the problem of high-dimensional optimization by decomposing the objective function.In this paper,MM algorithm is applied to the parameter estimation problem of mixed distribution model.The method of assembly and decomposition is used to construct the substitute function with separable parameters,which avoids the problems of complex expectation calculations and the inversion of high-dimensional matrices.

The connection of phytoplankton biomass in the Marguerite Bay polynya of the western Antarctic Peninsula to the Southern Annular Mode

Antarctic coastal polynyas are biological hotspots in the Southern Ocean that support the abundance of hightrophic-level predators and are important for carbon cycling in the high-latitude oceans.In this study,we examined the interannual variation of summertime phytoplankton biomass in the Marguerite Bay polynya(MBP)in the western Antarctic Peninsula area,and linked such variability to the Southern Annular Mode(SAM)that dominated the southern hemisphere extratropical climate variability.Combining satellite data,atmosphere reanalysis products and numerical simulations,we found that the interannual variation of summer chlorophyll-a(Chl-a)concentration in the MBP is significantly and negatively correlated with the spring SAM index,and weakly correlated with the summer SAM index.The negative relation between summer Chl-a and spring SAM is due to weaker spring vertical mixing under a more positive SAM condition,which would inhibit the supply of iron from deep layers into the surface euphotic layer.The negative relation between spring mixing and spring SAM results from greater precipitation rate over the MBP region in positive SAM phase,which leads to lower salinity in the ocean surface layer.The coupled physical-biological mechanisms between SAM and phytoplankton biomass revealed in this study is important for us to predict the future variations of phytoplankton biomasses in Antarctic polynyas under climate change.

Research on the Blended Online and Offline Teaching Mode of Ideological and Political Courses in Universities

With the development of information technology,the blended online and offline teaching mode has gradually become a new trend in the teaching of ideological and political theory courses in universities.This article analyzes the current situation and existing problems of blended online and offline teaching of ideological and political courses in universities,and explores how to effectively combine online and offline teaching resources to improve the teaching effectiveness of ideological and political courses in universities.

Mode decomposition of a noise suppressed mixing layer

Noise is generated in a two-dimensional mixing layer due to the growing of instability waves and vortex pairings. The adjoint-based control methodology has shown to be a robust tool to suppress noise radiation. The mode decomposition algorithms such as the compressible version of proper orthogonal decomposition （POD） and dynamic mode decomposition （DMD） are employed to analyze the spatial/spatial-temporal coherent structures for a consecutive data sets of the controlled mixing layer and its uncontrolled counterpart. The analyses of POD indicate that the y-direction body force control mainly modify the most energetic spatial structures, and increase the uniformity of the flow. The analyses of DMD show us prevalent frequencies and corresponding mode structures, and the stability characteristics of each mode can be obtained from DMD-spectrum. The spectral signatures illustrate that a lot of neutral/slightly damping modes emerging in uncontrolled flow within the frequency range （w 〈 0.4） are suppressed due to control, relevant spatial-temporal structures are also varied, which is coincident with the change of far-field noise spectra. From the view of mode decomposition, the action of control redistribute the energy for frequency components of ~ 〈 0.4 by weakening nonlinearities and regularizing corresponding dynamic structures in streamwise direction, and thus suppress the noise radiation. Moreover, the POD- and DMD-analysis in this study demon- strate that DMD can serve as an important supplement for POD in analyzing a time-resolved physical process.

Improvement of the Mirror Extending in Empirical Mode Decomposition Method and the Technology for Eliminating Frequency Mixing

The mirror extending approach proposed by Zhao and Huang in EMD method is improved in this paper. Mirror extending manner of data is kept unchanged, but the approach for determining envelopes is changed. When the end of data is obviously not extremum, the envelope is determined by the first inner extremum and the image value in the mirror, ignoring the value on the end. This improvement eliminates the frequency compression near the end and decreases the error. Meanwhile, tridiagonal equations are used and the calculation speed is much increased. The temporal process curve is more important in reflecting the real physical process and comparable with other phenomena. Frequency mixing in IMFs makes it impossible. A high frequency reconstruction (HFR) approach is proposed to eliminate common frequency mixing and reconstruct an IMF with all high frequency portions. By this approach, the IMFs without frequency mixing are obtained to express significative processes. The high frequency information restored in high frequency IMF can be extracted by general spectrum method. After obtaining IMFs by EMD method, some of the theoretical and technological issues still exist when using the IMFs. The consistency of IMFs with real physical process is discussed in detail. By virtue of the approach proposed in this paper, the EMD method can be widely used in various fields.

Adsorption behaviors of avian immunoglobulins and purification of immunoglobulin Y from chicken serum with mixed-mode resins

The importance of immunoglobulin Y(IgY) as a specific antibody equivalent to mammalian immunoglobulin G(IgG) is well recognized. However, production of highly purified IgY is still difficult due to the lack of specific purification methods. In this study, adsorption behaviors of Ig Y on four mixed-mode resins with functional ligands of 4-mercatoethyl-pyridine(MEP), 2-mercapto-1-methyli-midazole(MMI), 5-aminobenzi-midazole(ABI) and tryptophan-5-aminobenzi-midazole(W-ABI) were evaluated. The results showed that high adsorption ratio were found at p H 6.0–7.0 with little adsorption under acidic conditions. The resin with ABI ligand was then used to separate IgY from immunized chicken serum. An efficient process with Ig Y purity of 95% and recovery of 90% was developed after optimization of loading and elution p H and injection volume. The biological activity of the purified Ig Y was fully maintained. These results indicated that mixed-mode chromatography with specially-designed ligands has great potential for the separation of Ig Y from crude feedstock.

Kinematic and mixing characteristics of vortex interaction induced by a vortex generator model:a numerical study

The underlying effect of vortex interaction characterized by the merging and non-merging on mixing enhancement is of fundamental significance to understand the flow dynamics of strut injectors in scramjets.Starting from a simplified configuration of a vortex generator,this study focuses on the influence of geometric parameters on vortex structures and fluid mixing through compressible Navier-Stokes(NS)simulations.By adjusting the induction of outer vortices,the inner co-rotating vortex pair exhibits two modes of interaction(merging/separation regime)reflected by closer/farther vortex centers.Defined by the zero variation rate of the inner vortex spacing,the critical state of equilibrium is determined.The critical condition is well predicted by a theoretical model based on the Biot-Savart law.Through the introduction of mixedness and mixing time,the intrinsic impact of interaction modes on fluid mixing is revealed.Compared with the vortex dynamics in the merging regime,the one in the separation regime is more effective for passive scalar mixing augmentation.With efficient material stretching characterized by the higher interface stretching factor and averaging finite-time Lyapunov exponent(FTLE),the mixing time is shortened by as much as 2.5 times in the separation regime.The implication of the present two interaction regimes in mixing enhancement physically reflected by the averaging FTLE has the potential to improve the combustion performance and shorten the combustor chamber.

Self-Mixing Interference Effects in LD Pumped Multi-Mode Solid-State Laser

Based on the effective structure of the self-mixing interference effects,a general model for the self-mixing interference effects in the LD pumped solid-state laser has been established for the first time.The numerical simulation of the self-mixing interference signal has been done,the results show that when the external cavity length is integral times of 1/2,1/3,2/3,1/4,3/4 of the effective cavity length,the intensity of the self-mixing interference signals reach maximum in value.While that of single mode laser is integral times of half of the effective cavity length,the measuring precision of displacement of single mode laser is λ/2.A conclusion can be drawn from the above results that the measuring precision of displacement of multi-mode laser is higher than that of single mode laser.

从创新到发展:MM教育方式解构

为积极推进本土化教育理论的传承,探索国内优秀教育方式的形成与发展规律,研究立足于历史眼光和现代观念两个视角,回顾了MM教育方式发展历程,提出改革创新是MM教育方式的思想渊源,经世历练促进了MM教育方式的蓬勃开展.坚实的理论基础与学科特色,严密的实证研究与成果凝炼,以及教育方式的开放包容与普适等,丰富了MM教育方式的内涵,为MM教育方式的全面推广奠定了广泛的群众基础,取得了落地生根的优良效果.面向未来,MM教育方式要吸收和借鉴相关理论的优秀成果,加强自我革新,注重实验梯队建设,努力向外拓展和推广,逐步做优做强.

基于“雨课堂”的植物生理学混合式教学设计与探索

随着多媒体工具和网络覆盖普及,基于互联网的在线教育愈加便捷,但其优势并未在高校的课程教学中得到体现和充分应用。该文针对植物生理学的学科特点和教学现状,充分利用线上教学资源,针对性地选择教学内容和方法,以学生为主体、教师为主导,基于“雨课堂”等教学平台进行线上线下混合式教学模式初探,以期利用有限的学时和丰富的线上教学资源,整合线上和线下教学的优势,通过有效的管理方式组织实施,为深化信息化教学改革、提高植物生理学的教学效果奠定基础。

尾巨桉萌芽林与混交改造林径流水质变化特征

【目的】探讨桉树纯林及桉树混交林坡面径流水质变化特征,揭示水质变化的客观规律,为正确回答和解决桉树人工林水质问题,实现桉树人工林可持续发展提供重要科学依据。【方法】以桉树纯林、桉树×灰木莲混交林(带状混交、行间混交、株间混交)、灰木莲纯林为研究对象,选取对森林水质有关键影响作用的因子,采用连续监测与实验室分析相结合的方法,对比不同栽培模式条件下径流水质变化差异。【结果】1)试验样地坡面径流水pH值、COD、BOD5均达到我国农田灌溉水质标准(GB 5084—2021)对pH值(5.5~8.5)、COD(<150.00 mg·L^(-1))、BOD5(<60.00 mg·L^(-1))浓度的要求;2)桉树纯林坡面径流水中单宁含量(7.77 mg·L^(-1))显著高于其他样地,达到空白对照样地(1.22 mg·L^(-1))的6.4倍,桉树×灰木莲混交后可以有效降低坡面径流水中单宁含量,其中桉树×灰木莲行间混交模式效果最明显;3)桉树和灰木莲纯林坡面径流水中腐殖酸含量均高于混交林,其中桉树×灰木莲带状混交模式更有利于其坡面径流水中腐殖酸含量的降低。【结论】桉树混交模式的营建在保证坡面径流水质主要指标达标的同时能有效降低坡面径流水中单宁及腐殖酸含量,桉树混交栽培模式进一步缓解了桉树纯林对土壤酸碱性及微生物的影响。

基于OBE理念和课程思政的野外地质实习课程线上线下混合式教学模式探索

野外地质实习是地学类等高校专业人才实践能力和创新能力培养的重要环节,其线上线下混合式实习模式值得探索和完善。原有地质实习多以教师为中心,不利于发挥学生的主体学习能力;教学方式主要为线下教学,常受特殊事件(如疫情、极端天气等)的影响;课程思政与实习课程教学有效融合不够,造成课程思政环节滞后;考评方式不能客观地反映实习课程的教学效果和学生的综合学习效果等。针对这些问题,基于工程教育成果导向教育理念和课程思政建设纲要,紧密围绕野外地质实践教学实习课程特点和实践内容,以树立正确价值观、知识传授和能力培养作为实习课程三位一体的教学目标,充分利用现代信息技术,构建了野外地质实习课程线上线下混合教学模式;深度挖掘、精心设计课程思政内容并有机融入线上和线下教学,达到润物细无声的协同育人效果。构建全方面多元立体全生命周期课程教学评价体系,提升和优化线上线下教学效果,着力培养创新型地学人才的综合素质,提升野外地质实习课程的教育教学质量。

基于临床路径的多元混合教学法在内分泌住院医规范化培训中的探索

目的探讨基于临床路径(CP)的多元混合教学法在内分泌住院医规范化培训中的教学效果。方法对2020年1月-2020年12月内分泌科轮转的内科及全科住院医规范化培训97学员按照入科时间分为对照组(CPL+PBL+CBL)和观察组(CPL+PBL+改良CBL),通过教学效果、学员岗位胜任力、教学满意度三个维度进行定量研究。结果两组间出科考试理论成绩、教学满意度差异无显著性,P>0.05。观察组学员病例分析能力和岗位胜任力(CCMTV住培管理系统中360度评估)优于对照组,P<0.05。结论以CP教学法为基础,联合PBL、CBL教学法的多元混合教学模式适用于内分泌住院医规范化培训,在此基础上改良CBL教学法有利于学员临床思维和岗位胜任力的培养。基于临床路径的混合教学法在内分泌住院医规范化培训中具有良好的应用前景。

“自动控制原理”课程思政混合式教学探索

为兼顾专业教学与思政教育,探索了“自动控制原理”课程思政的线上线下混合教学模式。明确了专业思政与课程思政之间的关系,吸收马克思主义学院的教师进入教学团队,建立思政案例库,然后将思政教育融入线上、线下各个环节,并改进课程评价方式,形成了一套“自动控制原理”课程思政的线上线下混合教学模式。多年教学实践表明,该教学模式能够取得好的教学效果。

混合教学模式下课程教学改革探索——以“普通畜牧学”为例

“普通畜牧学”是农业院校草业科学、农业经济管理及马业科学学生的专业拓展课程之一。目前,随着现代化教学模式的推荐,该课程面临着改革的挑战,主要体现在教学理论、教学方法、教学手段和评价方式等方面。因此,需认识课程教学的不足之处,从而采取线上线下混合教学模式的教学方法,合理进行教学质量和教学效果的提升,激发学生的主观能动性,优化教学培养模式。根据教学中的实际问题,探索线上线下混合教学模式,为“普通畜牧学”课程质量和高校高质量发展提供了教学改革参考。

信息类专业课程思政与混合式教学改革研究——以韶关学院为例

以信息类专业的课程现状为研究对象,从政策视角着力推进课程思政与混合式教学双驱模式的建设,不仅要在意识上加强教育,学校层面重视,还要培养兼具专业知识与思政知识、熟练运用新的教学方法与模式的教师资源。同时分别设计了课程思政与混合式教学双驱模式改革具体实施方案,提出了双驱模式实施过程中的具体措施,希望能为其他工科专业教育提供启示,并促进教育信息化发展。

新医科背景下基于校院合作的妇产科护理学混合式教学模式的构建研究

目的探讨新医科背景下基于校院合作的混合式教学模式在妇产科护理学课程中的应用与效果。方法选择我校2019级110名护理本科生为对照组、2020级113名护理本科生为观察组。对照组采用传统教学模式,观察组采用新医科背景下基于校院合作的妇产科护理学混合式教学模式。课程结束后,比较两组的期末考试成绩、自我导向学习能力、评判性思维能力和教学满意度。结果观察组的期末考试成绩及优良率高于对照组(P<0.05)。观察组的自我导向评定量表各维度得分及总分均高于对照组(P<0.01)。观察组的评判性思维能力各维度得分及总分均高于对照组(P<0.05)。观察组的各项教学满意度评分均高于对照组(P<0.05)。结论新医科背景下基于校院合作的妇产科护理学混合式教学模式能有效提高学生的学习成绩、自我导向学习能力和评判性思维能力,进而能提高护理本科生整体教学质量。

线上线下混合教学模式下分子生物学课程的教学探索与实践

随着信息技术的发展和高校教学改革的深入,为提高分子生物学课程的教学质量和学生学习积极性,对分子生物学课程进行教学改革和实践很有必要。线上线下混合式教学模式已成为高等教育的一种热点教学模式。文章以分子生物学课程为例,从构建线上线下混合教学模式,优化教学内容,教学方法改革及构建多元化的教学评价体系等方面进行教学探索,为其它相关课程混合式教学的教学改革提供参考。线上线下混合教学模式的应用不但拓展了分子生物学课程课堂的时间和空间跨度,同时也丰富了学生的学习体验,有效提升了该课程的教学效果。

线上线下混合式教学在内经选读课程的应用

内经选读课程为学习《黄帝内经》打下坚实的基础。中医经典课程教学模式具有多样性,线上线下混合模式是目前教学发展的趋势,内经选读线上教学主要体现为平台选择、制作授课视频、教学资源上传到线上教学平台等,其线下教学模式以“启发式”创新教学著称的翻转课堂为代表。内经选读线上线下混合式教学模式不仅普遍提高了学生对中医经典的自主学习能力和解决问题的能力,还提升了中医经典教学和学生学习中医经典的效果,促进了师生间的深度互动。文章以南方医科大学2019级中西医临床医学本科专业的内经选读课程的线上线下混合式教学的实施情况为例进行总结,为后续教学积累经验。

基于学习通和BOPPPS的课程思政混合式教学模式的探索——以高职高专生理学课程为例

后疫情时代,线上线下混合式教学已成为高校教学的新常态,如何在混合式教学中实施好课程思政是一个亟待解决的问题。团队基于BOPPPS教学模型,利用超星学习通工具,将线上线下教学资源进行融合,并将思政元素有机融入教学的6个环节。实践表明,基于学习通和BOPPPS模型的课程思政混合式教学能有效激发学生的学习热情、促进课堂互动、提升育人成效。该模式为混合式教学改革服务课程思政建设提供了可能路径。