长盛不衰的51系列单片机

围绕着 51系列单片机产品种类的多样性 ,及其开发工具和操作系统的齐全性 ,介绍了虽然目前单片机界已呈现百花齐放的局面 ,但 51系列单片机仍保持长盛不衰的现象 ,并对 51系列单片机的新成员—— AD公司的 ADu C81 2给予简要介绍。     

How to Apply Nonlinear Subspace Techniques to Univariate Biomedical Time Series

In this paper, we propose an embedding technique for univariate single-channel biomedical signals to apply projective subspace techniques. Biomedical signals are often recorded as 1-D time series; hence, they need to be transformed to multidimensional signal vectors for subspace techniques to be applicable. The transformation can be achieved by embedding an observed signal in its delayed coordinates. We propose the application of two nonlinear subspace techniques to embedded multidimensional signals and discuss their relation. The techniques consist of modified versions of singular-spectrum analysis (SSA) and kernel principal component analysis (KPCA). For illustrative purposes, both nonlinear subspace projection techniques are applied to an electroencephalogram (EEG) signal recorded in the frontal channel to extract its dominant electrooculogram (EOG) interference. Furthermore, to evaluate the performance of the algorithms, an experimental study with artificially mixed signals is presented and discussed.      

利用计算机串口进行发动机瞬时转速测试

瞬时转速是发动机测试中的一个重大课题,笔者运用计算机接口知识,利用计算机串口测量发动机瞬时转速.测量、数据处理、曲线显示等全部由计算机完成,结构简单,测试精度高,为转速测量开辟了一个新的途径.     

零位光栅刻线序列的计算机模拟设计

在使用光栅进行长度和角度测量的应用中提供可靠的参考基准是非常重要的，根据零位脉冲产生的基本理论，并结合实际应用中的一些客观要求，采用计算机模拟，寻找最佳零位刻线序列，达到了预期目的，在此基础上进行了对称式零位刻线序列的设计。     

A Computer Proof of a Series Evaluation in Terms of Harmonic Numbers

 A fruitful interaction between a new randomized WZ procedure and other computer algebra programs is illustrated by the computer proof of a series evaluation that originates from a definite integration problem. Received: April 9, 2002 Keywords: Computer algebra, Hypergeometric summation, Definite integration, WZ method. The first author was supported in part by NSF grant DMS-0103897. The third author was supported by SFB grant F1305 of the Austrian FWF.     

Persistence,Engagement, and Migration in Engineering Programs

Records from the Multiple‐Institution Database for Investigating Engineering Longitudinal Development indicate that engineering students are typical of students in other majors with respect to: persistence in major; persistence by gender and ethnicity; racial/ethnic distribution; and grade distribution. Data from the National Survey of Student Engagement show that this similarity extends to engagement outcomes including course challenge, faculty interaction, satisfaction with institution, and overall satisfaction. Engineering differs from other majors most notably by a dearth of female students and a low rate of migration into the major. Noting the similarity of students of engineering and other majors with respect to persistence and engagement, we propose that engagement is a precursor to persistence. We explore this hypothesis using data from the Academic Pathways Study of the Center for the Advancement of Engineering Education. Further exploration reveals that although persistence and engagement do not vary as much as expected by discipline, there is significant institutional variation, and we assert a need to address persistence and engagement at the institutional level and throughout higher education. Finally, our findings highlight the potential of making the study of engineering more attractive to qualified students. Our findings suggest that a two‐pronged approach holds the greatest potential for increasing the number of students graduating with engineering degrees: identify programming that retains the students who come to college committed to an engineering major, and develop programming and policies that allow other students to migrate in. There is already considerable discourse on persistence, so our findings suggest that more research focus is needed on the pathways into engineering, including pathways from other majors.     

Synthesis,Functionalization, and Biomedical Applications of Multifunctional Magnetic Nanoparticles

Synthesis of multifunctional magnetic nanoparticles (MFMNPs) is one of the most active research areas in advanced materials. MFMNPs that have magnetic properties and other functionalities have been demonstrated to show great promise as multimodality imaging probes. Their multifunctional surfaces also allow rational conjugations of biological and drug molecules, making it possible to achieve target‐specific diagnostics and therapeutics. This review first outlines the synthesis of MNPs of metal oxides and alloys and then focuses on recent developments in the fabrication of MFMNPs of core/shell, dumbbell, and composite hybrid type. It also summarizes the general strategies applied for NP surface functionalization. The review further highlights some exciting examples of these MFMNPs for multimodality imaging and for target‐specific drug/gene delivery applications.     

Yolk–Shell Nanostructures: Design,Synthesis, and Biomedical Applications

Yolk–shell nanostructures (YSNs) composed of a core within a hollow cavity surrounded by a porous outer shell have received tremendous research interest owing to their unique structural features, fascinating physicochemical properties, and widespread potential applications. Here, a comprehensive overview of the design, synthesis, and biomedical applications of YSNs is presented. The synthetic strategies toward YSNs are divided into four categories, including hard‐templating, soft‐templating, self‐templating, and multimethod combination synthesis. For the hard‐ or soft‐templating strategies, different types of rigid or vesicle templates are used for making YSNs. For the self‐templating strategy, a number of unconventional synthetic methods without additional templates are introduced. For the multimethod combination strategy, various methods are applied together to produce YSNs that cannot be obtained directly by only a single method. The biomedical applications of YSNs including biosensing, bioimaging, drug/gene delivery, and cancer therapy are discussed in detail. Moreover, the potential superiority of YSNs for these applications is also highlighted. Finally, some perspectives on the future research and development of YSNs are provided.     

聚乳酸／纳米二氧化硅复合材料分子量的影响因素

以丙交酯和改性后的纳米二氧化硅为原料,在催化剂作用下,用原位聚合法制备了聚乳酸纳米二氧化硅复合材料。讨论了催化剂的种类和用量、反应时间、反应温度、纳米二氧化硅的用量等因素对复合材料分子量的影响。结果表明,最优的反应条件为:采用辛酸亚锡为催化剂,催化剂用量和二氧化硅用量分别为丙交酯用量的0.25%(质量分数,下同)和5%,在140℃油浴中,氮气保护下反应72 h,可得到重均分子量为1.5091×105的聚乳酸纳米二氧化硅复合材料。     

Recent Advances in Higher‐Order,Multimodal, Biomedical Imaging Agents

Advances in biomedical imaging have spurred the development of integrated multimodal scanners, usually capable of two simultaneous imaging modes. The long‐term vision of higher‐order multimodality is to improve diagnostics or guidance through the analysis of complementary, data‐rich, co‐registered images. Synergies achieved through combined modalities could enable researchers to better track diverse physiological and structural events, analyze biodistribution and treatment efficacy, and compare established and emerging modalities. Higher‐order multimodal approaches stand to benefit from molecular imaging probes and, in recent years, contrast agents that have hypermodal characteristics have increasingly been reported in preclinical studies. Given the chemical requirements for contrast agents representing various modalities to be integrated into a single entity, the higher‐order multimodal agents reported so far tend to be of nanoparticulate form. To date, the majority of reported nanoparticles have included components that are active for magnetic resonance. Herein, recent progress in higher‐order multimodal imaging agents is reviewed, spanning a range of material and structural classes, and demonstrating utility in three (or more) imaging modalities.     

An Interactive,Video‐Teleconferenced,Graduate Course in Biomedical Engineering

A two‐semester, video‐teleconferenced (2‐way video/audio) course entitled Principles of Biomedical Engineering I and II was offered from 1999 to 2001 for graduate students enrolled at Purdue University (PU; West Lafayette, IN) and Indiana University/Purdue University at Indianapolis (IUPUI; Indianapolis, IN). Results of the study provided evidence that during the control (i.e., traditional lecture) distance learning environment, on‐campus students consistently received statistically significant higher final course grades than off‐campus students. In contrast, upon implementation of interactive distance learning methods, the on‐ and off‐campus students received similar (not statistically different) final grades. In this manner, the study demonstrated that effective use of video‐teleconferencing occurs when students at remote‐sites actively participate in the learning experience rather than passively observe the lectures on a television monitor (as occurs during traditional distance learning lectures).