巧用渐近线绘制对数相频特性曲线

渐近线法绘制对数相频特性曲线（相位Bode图）是一种新方法,巧用渐近线绘制系统开环相位Bode图具有方便、快捷等优点。其中惯性、振荡等典型环节相位Bode图的渐近线的绘制法较为典型,由此总结出系统开环相位Bode图的渐近线绘制法。     

基于PRO/E的精确三维斜齿轮参数化建模

斜齿轮是参数化建模的热点与难点。当前较为流行的斜齿轮参数化建模方法仍存在曲线的近似替代、齿形生成随意、无精度检测方法等一系列问题。为解决上述问题,从齿条型刀具加工齿轮的范成原理入手,推得齿廓渐开线方程与过渡曲线方程;参数化建模所需基本模型,通过PRO/E的参数化建模功能完成斜齿轮的建模;并提出了一种斜齿轮模型精度的检验方法。     

小学数学应用问题模型构建的实践与探索

正一、问题的提出"问题解决"与"数学建模"是数学教育的热点、焦点问题。在近几届国际数学教育大会上,"问题解决、模型化和应用"被列为几个主要研究的问题之一,且普遍赞同:通过开展"数学建模"活动来推动数学教育改革。随着我国课程改革的深入,数学建模活动已扩展到义务教育阶段,且成为数学学习的重要目标。2011版《数学课程标准》将数学"建模—用模"     

高职数学教材编写的思考与探索

高职数学教材的编写应以应用能力培养为主线,采用模块编写方式,将数学建模的思想与方法融入其中,兼顾人文教育,以"问题情境—展现知识—实现应用"的思路呈现教学内容。     

建模，让数学学习走向深处

数学建模指向模型思想和建模能力培养的全过程,通过"基于实际问题—建立数学模型—求解数学模型—应用数学模型",帮助学生逐步形成和提升建模能力,核心价值在于通过解决一道题从而解决一类题。结合课例展开建模教学的策略论述,唤醒教师的数学建模教学意识,培养学生的数学建模能力。     

建模思想在高中数学教学中的渗透与应用

在高中数学课堂中渗透建模思想,以建模实例来丰富并建构数学知识体系,拓展实际应用,有利于学生构建缜密的数学思维,加深教材知识与实际生活的联系,能够以数学眼光来分析问题.本文以"问题情境—模型建立—模型求解—模型拓展"的教学思路,浅谈建模思想在高中数学教学中的渗透与应用.     

指向核心素养的初中数学建模意识培养实践

数学建模是运用数学模型解决实际问题的一种方式,是初中生应具备的核心素养之一。以三类问题为例,探究数学建模的方法与策略,能培养学生的模型观念、应用意识和初步建模能力,让其亲身经历“实际问题—数学问题—建立模型—求解验证—问题解决”的全过程,启智明理,体悟本质,进而提升其建模意识,培养数学核心素养。     

刍议小学数学应用题“问题—建模—应用”教学模式

在小学数学教学中,应用题一直受到教育者的广泛关注,对学生进行应用题训练,不仅可以提高学生的数学能力,还可以增强学生的数学素养,同时也是培养学生逻辑思维能力以及对问题分析与判断能力的基础。因此,在开展数学教学的过程中,采用"问题—建模—应用"模式可以有效提高学生的解题能力。基于此,对在小学数学教学中运用"问题—建模—应用"模式进行了简要阐述,并提出几点看法,仅供参考。     

小学数学建模思想的渗透策略

<正>数学课程标准倡导以"问题情景—建立模型—应用与拓展"作为小学数学的基本叙述模式,针对事物的特征或数量相依关系,概括表述出一种数学结构。那么何谓数学模型?如何在课堂教学中渗透"建模"思想,拓展学生的思维?一、从问题创设入手,感知建模思想在小学数学教学中,要让学生建立建模思想,就要从现实生活背景入手,让学生根据生活实际,本着解决问题     

曲线系:从知识点还原到研究工具

1.引言"问题—工具—解"是推动数学发展的重要方式.当问题得到解决后,解决问题的工具便凝固于教科书中,成了知识点.例如,在解决求曲线的切线及曲线围成面积的过程中,人们发展了无穷小分析的研究方法,极限成了人们解决新     

Supposer et postuler pour produire des connaissances scientifiques: une évidence ou une conquête théorique? Une étude des points de vue d'étudiants

Résumé De manière générale, l'évidence sensorielle et, plus particulièrement, visuelle constitue pour les étudiants le principal fondement du savoir scientifique: nul besoin de supposer pour connaître, tout est donné ou presque. Du point de vue de l'enseignement des sciences, cette croyance à saveur réaliste est particulièrement critique, notamment parce qu'elle conduit à penser que les concepts, lois et théories scientifiques procèdent d'un monde de matérialités plutôt que d'un monde de modèles et de relations. Au cours d'une recherche effectuée auprès d'un groupe-classe de 35 étudiants durant douze semaines, nous avons pu observer que, pour la majorité des étudiants, la compréhension du caractère construit et consensuel du savoir scientifique était facilitée par le développement d'une métaréflexion sur leurs propres productions de connaissance et les inévitables postulats et suppositions qui les fondent. Nous avons également pu observer qu'il découle de cette activité réflexive un modèle de science qui se distingue des modèles initialement tenus par les étudiants, par le pouvoir créateur et, surtout, le pouvoir de théoriser qu'il comporte: postuler, supposer, jauger collectivement de la plausibilité des résultats plutôt qu'en appeler à une instance occulte, voilà quelques-unes des conquêtes théoriques qu'ils ont effectuées et sur lesquelles nous allons nous attarder.

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Sensorial, and more specifically, visual evidence is generally regarded by students as the basis for scientific knowledge: no need to postulate to understand, all is almost or practically given. From a science-teaching standpoint, this rather realistic approach is critical and leads to the belief that scientific concepts, laws, and theories stem from a world of materiality rather than from a world of models and relationships. During a 12-week study a group of 35 college students, we observed that for the majority of them, the development of metareflection on how they produce knowledge, with the inevitable and inherent postulates and conjecture, facilitated their understanding of the constructed and consensual character of scientific knowledge. We also observed that this reflexive activity facilitated the development of a new approach to science that differed from those models previously used by the students in its creative potential and, more importantly, in the power of its theoretics: to postulate, suppose, and collectively estimate the plausibility of results rather than calling up occult instances. These and other theoretical achievements will be discussed in this paper.

     

Retooling Education: Testing and the Liberal Arts

The motivation and methodology for measuring intelligence have changed repeatedly in the modern history of large-scale student testing. Test makers have always sought to identify raw aptitude for cultivation, but they have never figured out how to promote excellence while preserving equality. They’ve settled for egalitarianism, which gives rise to “culturally fair” tests that substitute vagaries for knowledge, deprive students of any real appreciation for language, and trivialize education. Robert Jackson yearns for traditional oratorical approaches to schooling that venerate and imitate essential, time-tested masters. Unfortunately, he writes, such an education defies measurement with today’s multiple-choice instruments.

A Longitudinal Analysis of the Relations Among Professional Development,Educators’ Beliefs and Perceived Skills,and Response-to-Intervention Implementation

ABSTRACT

Professional development is a critical systems-level intervention thought to facilitate Response-to-Intervention (RtI) implementation. The current study examined the relations between professional development, educator outcomes, and problem-solving implementation within an RtI framework using growth curve modeling. School leadership teams from pilot schools (n = 34) participated in 3 years of training. Pilot schools also received job-embedded coaching. Comparison schools (n = 27) provided a referent group. Results indicated that problem-solving implementation increased faster at pilot schools (β = 0.10, SE = 0.05, t = 2.03, p < .05). In addition, beliefs regarding data-based decision-making (β = 0.36, SE = 0.17, t = 2.13, p < .05) and perceived problem-solving skills applied to academics (β = 0.30, SE = 0.10, t = 3.07, p < .01) positively related to implementation. Implications include the needs to further explore professional development activities and for consultants to utilize evidence-based professional development principles when supporting RtI implementation.     

A validated instrument measuring students' perceptions on plastinated and three-dimensional printed anatomy tools

Due to the modernization of the medical curriculum and technological advancements, anatomy education has evolved beyond cadaveric dissection alone. Plastination techniques, three-dimensional (3D) modeling, and 3D printing technologies have progressively gained importance. However, there are limited valid and reliable surveys to evaluate students' perceptions of these new anatomy tools. Hence, this study aimed to develop a validated instrument to measure students' learning satisfaction, self-efficacy, humanistic values, and perceived limitations of plastinated and 3D printed models. A 41-item survey (five-point Likert scale, 1 = strongly disagree to 5 = strongly agree) was administered to Year 1 undergraduate medical students following a randomized controlled crossover study that evaluated plastinated and 3D printed cardiac and neck models. Ninety-six responses were received, and a factor analysis was performed with the Kaiser–Meyer–Olkin sampling adequacy of 0.878. The confirmatory factor analysis yielded a 4-factor, 19 items model that had a good fit with the latent constructs of $x$² (147) = 211.568, P < 0.001, root mean square error of approximation = 0.068, root mean square residual = 0.064, comparative fit index = 0.946, and Tucker Lewis index = 0.937. The Cronbach's alpha for the individual factors ranged from 0.74 to 0.95, indicating good internal consistency. This demonstrated a psychometrically valid and reliable instrument to measure students' perceptions toward plastinated and 3D printed models.     

“Street Love”: How Street Life Oriented U. S. Born African Men Frame Giving Back to One Another and the Local Community

This Participatory Action Research (PAR) project worked with four active street life oriented U. S. Born African men, to document how a community sample of street life oriented U. S. Born African men between the ages of 16–65, frame and use “street life” as a Site of Resiliency (Payne, Dissertation, 2005; Journal of Black Psychology 34(1):3–31, 2008). Qualitative data was collected in the form of 20 individual and two group interviews. These data reveal an inter-generational, conceptualization and use, of the term “street love” in street life oriented U. S. born African men. Also, these data reveal that notions of “street love” extend out a critique of community professionals (e.g., community researchers/interventionists, social workers, etc.) as being unable and unwilling to produce “real help” in the local community. Examples of street love, revealed in the study, include the men offering advice/counsel, money or “free turkeys” during Thanksgiving to one another as well as other members of the local community. Results support Payne’s (2005) three-dimension conceptualization of “street love”: (1) individual, (2) group and (3) communal level expressions of “street love”.

Childhood disclosure of sexual abuse: Necessary but not necessarily sufficient

Prevention programs often encourage sexually abused children to disclose without fully considering the potential for adverse consequences. This study examined the impact of disclosure on abuse cessation and later adult symptomatology. A clinical sample of 301 adult survivors completed the Impact of Event Scale (IES/IES-R), and the Beck Depression Inventory (BDI-II). Participants were divided into 3 groups: Nondisclosure (n = 221), Disclosure/Abuse Ended (n = 25), and Disclosure/Abuse Continued (n = 55). Multivariate analyses of covariance, adjusting for abuse characteristics (age of onset, penetration, and number of perpetrators) and other trauma exposure, revealed significant differences in psychiatric symptom severity among the three groups, Wilks’ λ = 0. 95, F (6, 584) = 2.69, p = 0.014, η_p² = 0.03. Specifically, those in the Disclosure/Abuse Continued group scored significantly higher on the IES/IES-R Intrusion subscale (p = 0.04) and the BDI-II (p = 0.01), as compared to the Nondisclosure group. The Disclosure/Abuse Ended group did not differ significantly from the other groups. Results suggest that disclosure may be detrimental unless adequate steps are taken to ensure abuse cessation and appropriate treatment.     

Phase diagram estimation of the Al2O3-SiO2-Re2O3 systems

Nine limiting binaries of Al₂O₃-SiO₂-Re₂O₃(Re=Nd, Sm, Gd and La) system are assessed. The binary diagrams or experimental information from Toropov, Mizuno, Aramaki, Bondar, Rolin and Coutures are optimized with the substitutional model of Kaufman and Nesor and the approximate formula of fusion free energy for rare earth element oxides of Wu and Pelton. The extracted Gibbs free energies of pure solid oxides and stoichiometric phases and the solution parameters are used to estimate the corresponding binaries, liquidus surfaces and a series of isothermal sections of four ternaries Al₂O₃-SiO₂-Nd₂O₃, Al₂O₃-SiO₂-Sm₂O₃, Al₂O₃-SiO₂-Gd₂O₃, and Al₂O₃-SiO₂-La₂O₃. In the Al₂O₃-SiO₂-Gd₂O₃ system samples as fired at exact temperature with different compositions were analyzed by X-ray diffractometer and the detected results are fitted with the calculation of isothermal sections. Supported by State Key Lab of High Performance Ceramics and Superfine Micro-structure (9517 and 9708)