项目教学法在《统计学》中的应用

在《统计学》教学中,统计分析部分数学性较强,有的内容学生容易混淆且难以掌握和理解,为发挥学生的主观能动性、提高学生学习兴趣、增强课堂教学活力、使学生更好的掌握教学内容,可以采用项目教学法。以"平均指标"这一项目为例,通过项目分解、学生分组、组内分工、成果汇报、教师点评等几个步骤进行教学,有利于提高教学效果和教学质量。     

基于PICl8F4620的信号发生技术研究

波形信号发生器是一种常见的信号源,广泛的应用在高职高专、普通高校的理工科基础实验中。目前使用的波形信号发生器大部分是利用51单片机及其相关电子电路组成,体积较大、产生的波形类型较少且准确度较低。而采用PICl8F4620单片机设计的信号发生器,可以产生方波、三角波、锯齿波和正弦波等四种波形,在完全能够满足理工科的基础实验信号需求的同时,对波形的周期、频率等关键参数具有数字化和在线调整等优点。     

"高校图书馆事实数据库"统计指标修订情况概述

从原统计指标存在的主要问题、修订目标、主要修订内容举要三个方面,对本次"高校图书馆事实数据库"统计指标的修订情况作了概述。     

Assistant principals in high-stakes accountability environments: The effects of job attributes and school characteristics

This study addressed the topic of job specifications and school characteristics since there is a shortage of quality AP applicants in high-stakes accountability environments. It is important to learn about allocation of duties from educational administrators with on-the-job experience as well as to learn why current APs would consider applying for other AP positions. The purpose of this study was to investigate the impact of job attributes (instruction, discipline), school level (elementary, middle, high), and school achievement (in-need-of-assistance, progressing, meets goal) on applicant’s rating of an AP position. This research study used an experimental design. A main effect for job attributes indicated that instruction was significantly higher than discipline when attracting assistant principals. Implications for practice and research are discussed.     

Exponential stabilization of sampled-data fuzzy systems via a parameterized fuzzy Lyapunov-Krasovskii functional approach

This paper devotes to stabilize nonlinear systems based on Takagi-Sugeno (T-S) fuzzy models, where only sampled state is available. Note that the membership functions (MFs) between T-S fuzzy models and fuzzy controllers are asynchronous under a sampling mechanism, a fuzzy state feedback controller with asynchronous MFs is introduced. A new parameterized fuzzy Lyapunov-Krasovskii functional (PFLKF) approach is presented to ensure that the closed-loop system is exponentially stable and there exists a large well-defined domain of attraction. In general, it is difficult to compute in advance the upper bounds of the time derivatives of MFs, where these time derivatives appear in the time derivative of the PFLKF or the errors of the asynchronous MFs. To this end, a novel quadratic inequality is established to characterize the time derivatives of MFs. Then an MF-dependent exponential stability criterion is given in terms of linear matrix inequalities, and a co-design method for the controller gains and the domain of attraction is presented. Finally, three illustrative examples show the effectiveness and advantages of the proposed approach.     

Robust active suppression for body-freedom flutter of a flying-wing unmanned aerial vehicle

Flying-wing unmanned aerial vehicles have received extensive attention over the past decade because of their excellent aerodynamic and stealth performance. However, the aeroelastic interaction problems among unsteady aerodynamics, flight dynamics, and structural dynamics, such as the body-freedom flutter, are still open. This paper presents the study of a robust control scheme for active body-freedom flutter suppression of a flexible flying-wing unmanned aerial vehicle. The control objective is to expand the boundary of body-freedom flutter and to enhance the control robustness to external unknown disturbance simultaneously. The paper begins with the modeling procedure of a parameter-varying aeroservoelastic plant for the design of control law. Then, it presents how to synthesize a robust controller so as to suppress the flutter instability for a wide flight range of dynamic pressures. Afterwards, the paper shows how to analyze the flutter stability of the closed-loop system and the robustness of the controller, respectively. The numerical results demonstrate that the proposed robust controller can not only expand the flutter boundary of the unmanned aerial vehicle by 30%, but also exhibit the strong robustness to external disturbance.     

High-gain fractional disturbance observer control of uncertain dynamical systems

Disturbance observer-based control allows to compensate unknown inputs, however, in most cases, requiring their integer-order differentiability. In this paper, a novel disturbance observer-based state feedback controller is proposed to compensate a more general class of fractional-, but not necessarily integer-order, differentiable unknown inputs. The proposed fractional PI-like structure yields precise conditions for feedback gain tuning. Remarkably, the resulting controller rejects non-differentiable disturbances with a smooth controller, guaranteeing robustness, an outstanding features for tracking tasks, under a prescribed practical stability regimen. A comparison to a fractional sliding mode observer is conducted via simulations to highlight the reliability of the proposed scheme.     

An Early College Initiative in an Urban,High-Poverty High School: First-Year Effects on Student Achievement and Non-Academic Indicators

The Early College High School (ECHS) initiative developed in response to calls to significantly decrease the number of first-generation college and underserved students of color and from poverty who are high school dropouts or marginally graduates (i.e., ill prepared for college). The ECHS model is different from other educational reforms in that secondary and postsecondary faculty work collaboratively to align curriculum and supports that facilitate a successful high school-to-college transition. The purpose of this study was to evaluate the effects of the initial implementation of ECHS on student achievement and nonacademic indicators in a high-poverty setting. Results indicated that, after an initial year of implementation, achievement results on criterion-referenced tests were significantly higher for all students relative to matched control students, but the statistically and practically significant impact on norm-referenced tests was limited to students enrolled in ECHS courses; school attendance remained the same, but suspensions were decreased. Implications for high school reform and research are discussed.     

高校非天文学专业本科生天文学课的教学改革

文章从中国高校天文学课程的情况及存在的问题入手,结合笔者近五年来在贵州大学从事天文学基础课程的教学经验。总结了我们在非天文学专业本科生天文学课程的教学内容、方法和改进措施,以及所取得的教学成果。     

三叶悬钩子对大鼠酒精性肝炎保护作用

目的：：观察三叶悬钩子乙醇提取物对大鼠酒精性肝炎的保护作用。方法：90只大鼠,随机分为6组,每天上午8：00灌胃1次,正常组大鼠灌胃给蒸馏水,其余5组大鼠灌胃给白酒,连续灌胃28 d,建立大鼠酒精性肝炎模型;第15天开始,每天上午9：00各组大鼠均以相应药物灌胃1次,连续灌胃14 d;第28天末次灌胃后,取血、取肝脏,检测血清天门冬氨酸氨基转移酶（GOT）、丙氨酸氨基转移酶（GPT）活性及肝组织丙二醛（MDA）含量、超氧化物歧化酶（SOD）活性;观察肝脏指数及肝组织病理变化。结果：三叶悬钩子乙醇提取物能显著降低肝炎大鼠GPT、GOT活性和MDA含量,能显著提高肝炎大鼠SOD活性;能显著降低肝炎大鼠肝脏指数;能显著减轻肝炎大鼠肝组织水肿和脂肪变性。结论：三叶悬钩子对大鼠酒精性肝炎有保护作用。