Project ExCEL: Web‐based Scanning Electron Microscopy for K‐12 Education

Project ExCEL (Extended Classroom for Enhanced Learning) brings the capabilities of scanning electron microscopy (SEM) into classrooms. University and industry personnel, working together, have developed a web‐based interface to allow schools to control a modern SEM. The interface allows a user control of the operating parameters of the microscope, stage movement, and chemical analysis. Such total control is not available on any other system. Since Iowa State University (ISU) pioneered the idea of remote SEM for education, researchers have learned that providing teachers access to sophisticated equipment does not ensure that it will be used. Teachers are busy, and structured curriculums are not conducive for incorporating the SEM into classes. A lack of teacher knowledge of SEMs also discourages their use. To overcome these problems, College of Engineering and College of Education faculty are working together to train future teachers in the SEM. The web‐based SEM is being used in education courses, and selected students (who receive additional training) prepare lesson plans and present their work to the class. In‐service teachers receive instruction in the web‐based SEM through workshops. By using this integrated approach, all science teachers in Iowa will eventually gain the confidence to use the SEM in their classrooms.     

A Web‐based and Group Learning Environment for Introductory Environmental Engineering

The use of computer‐based technology is becoming more prevalent in the classroom. As a part of an educational research project sponsored by the GE Foundation, strategies for augmenting a course, Introduction to Environmental Engineering (CE 280), were investigated including cross‐disciplinary experiences in teamwork, design, and the use of advanced teaching technologies such as the web. Interactive tools to assist student learning were developed and refined. Efforts have focused on developing an extensive website, web‐based quizzes and homework assignments, and tutorials. Base groups were used to provide both intellectual and emotional support to students. This paper summarizes the development of this course and the impact of rapid feedback on the progression of student understanding.     

Foundational Aspects of Student‐Controlled Learning: A Paradigm for Design,Development, and Assessment Appropriate for Web‐Based Instruction

This paper presents a strategy for the design and organization of materials for Web‐based instruction (WBI) founded upon cognitive modeling for the identification and organization of the major concepts in the domain of interest, based upon the Pathfinder paradigm. The original purpose of the Pathfinder paradigm was to model aspects of human semantic (associative) memory. A brief introduction to the Pathfinder paradigm is presented, and the rationale for its use in WBI is discussed. The development of this paradigm for WBI, in the context of eliciting and representing knowledge from domain experts, and its use in a pilot study is described. The domain used for the pilot study was the A* search algorithm, embedded within an introductory course in artificial intelligence. Assessment of the paradigm is also discussed, and preliminary methods are applied to the pilot study.     

Study of Usage Patterns and Learning Gains in a Web‐based Interactive Static Course

Background Courseware for engineering education can feature many discrete interactive learning elements, and typically student usage is not compelled. To take advantage of such courseware, self‐regulation of learning may be necessary. Evaluation of courseware should consider actual usage, learning gains, and indications of learning self‐regulation. Purpose (Hypothesis ) The research question focuses on how students' interactions with the courseware affect their learning gains. The hypothesis tested is that learning gains from online courseware increase with usage, and particularly with usage that suggests learning self‐regulation. Design /Method Students in a lecture‐based statics course were assigned to study previously developed courseware as part of homework assignments. Learning gains were deduced from pre‐ and post‐ paper and pencil diagnostic quizzes, and from the first class exam. Credit was based on quiz scores, rather than courseware usage. Usage of interactive elements of the courseware was inferred from log files of students' interactions with the courseware, and patterns suggesting learning self‐regulation were identified. Results High, statistically significant learning gains were found. Substantial usage was evident, with core learning activities initiated by, on average, three‐quarters of students. Learning gains and performance on the relevant class exam appeared to be more closely correlated with usage that indicated self‐regulation of learning rather than with total usage of the courseware. Conclusions Methods of assessing courseware should go beyond courseware features, learning gains, and student self‐reports of effectiveness to include monitoring of actual usage and analyses relating usage to learning. Self‐regulation of learning is likely to be critical to successful usage of courseware, and courseware should be designed to encourage it.     

Condition‐based Maintenance Optimization Using Neural Network‐based Health Condition Prediction

Artificial neural network (ANN)‐based methods have been extensively investigated for equipment health condition prediction. However, effective condition‐based maintenance (CBM) optimization methods utilizing ANN prediction information are currently not available due to two key challenges: (i) ANN prediction models typically only give a single remaining life prediction value, and it is hard to quantify the uncertainty associated with the predicted value; (ii) simulation methods are generally used for evaluating the cost of the CBM policies, while more accurate and efficient numerical methods are not available, which is critical for performing CBM optimization. In this paper, we propose a CBM optimization approach based on ANN remaining life prediction information, in which the above‐mentioned key challenges are addressed. The CBM policy is defined by a failure probability threshold value. The remaining life prediction uncertainty is estimated based on ANN lifetime prediction errors on the test set during the ANN training and testing processes. A numerical method is developed to evaluate the cost of the proposed CBM policy more accurately and efficiently. Optimization can be performed to find the optimal failure probability threshold value corresponding to the lowest maintenance cost. The effectiveness of the proposed CBM approach is demonstrated using two simulated degradation data sets and a real‐world condition monitoring data set collected from pump bearings. The proposed approach is also compared with benchmark maintenance policies and is found to outperform the benchmark policies. The proposed CBM approach can also be adapted to utilize information obtained using other prognostics methods. Copyright © 2012 John Wiley & Sons, Ltd.     

Reducing Oxygen Evolution Reaction Overpotential in Cobalt‐Based Electrocatalysts via Optimizing the “Microparticles‐in‐Spider Web” Electrode Configurations

Sluggish kinetics of the multielectron transfer process is still a bottleneck for efficient oxygen evolution reaction (OER) activity, and the reduction of reaction overpotential is crucial to boost reaction kinetics. Herein, a correlation between the OER overpotential and the cobalt‐based electrode composition in a “Microparticles‐in‐Spider Web” (MSW) superstructure electrode is revealed. The overpotential is dramatically decreased first and then slightly increased with the continuous increase ratio of Co/Co₃O₄ in the cobalt‐based composite electrode, corresponding to the dynamic change of electrochemically active surface area and charge‐transfer resistance with the electrode composition. As a proof‐of‐concept, the optimized electrode displays a low overpotential of 260 mV at 10.0 mA cm^?2 in alkaline conditions with a long‐time stability. This electrochemical performance is comparable and even superior to the most currently reported Co‐based OER electrocatalysts. The remarkable electrocatalytic activity is attributed to the optimization of the electrochemically active sites and electron transfer in the MSW superstructure. Theoretical calculations identify that the metallic Co and Co₃O₄ surface catalytic sites play a vital role in improving electron transport and reaction Gibbs free energies for reducing overpotential, respectively. A general way of boosting OER kinetics via optimizing the electrode configurations to mitigate reaction overpotential is offered in this study.     

Optimal Mean and Tolerance Allocation Using Conformance‐based Design

In this paper, we invoke probability constrained optimization to establish a framework for allocating means and tolerances in design for quality that focuses on customer satisfaction at predictable cost levels. The optimal allocation minimizes the production costs while ensuring that responses conform probabilistically to their specification limits. An overall system probability of conformance is obtained from a quality policy (e.g. defect rate, process capability index). Probabilities are evaluated using limit‐state functions and fast integration methods. The three quality metrics (i.e. target/larger/smaller‐is‐best) and robustness are addressed naturally. The methodology is developed in detail and compared with the traditional minimum total cost approach. Optimal means and tolerances are found for an electro‐mechanical servo system and a power division circuit to illustrate the practicality and potential of the approach. Copyright © 2005 John Wiley & Sons, Ltd.     

Thermo‐Switchable Materials Prepared Using the OEGMA‐Platform

We describe here the advantages of oligo(ethylene glycol)‐based (co)polymers for preparing thermoresponsive materials as diverse as polymer‐enzyme bio‐hybrids, injectable hydrogels, capsules for drug‐release, modified magnetic particles for in vivo utilization, cell‐culture substrates, antibacterial surfaces, or stationary phases for bioseparation. Oligo(ethylene glycol) methacrylates (OEGMAs) can be (co)polymerized using versatile and widely‐applicable methods of polymerization such as atom transfer radical polymerization (ATRP) of reversible addition‐fragmentation chain‐transfer (RAFT) polymerization. Thus, the molecular structure and therefore the stimuli‐responsive properties of these polymers can be precisely controlled. Moreover, these stimuli‐responsive macromolecules can be easily attached to–or directly grown from–organic, inorganic or biological materials. As a consequence, the OEGMA synthetic platform is today a popular option for materials design. The present research news summaries the progress of the last two years.     

Image‐based Continuous Displacement Measurements Using an Improved Spectral Approach

Digital Image Correlation algorithms capable of determining continuous displacement fields are receiving growing attention in the field of mechanical properties identification. In this paper, we develop an Improved Spectral Approach (ISA) to reconstruct continuous displacements based on their Fourier decomposition. This approach leads to a time and memory‐efficient algorithm, thanks to the fast Fourier transform. Moreover, the Fourier‐based decomposition enables accurate heterogeneous measurements. Improvements consist in increasing the accuracy and convergence rate as well as dealing with non‐periodic displacements and images. Furthermore, a theoretical framework is presented to quantify the noise sensitivity of the ISA from which useful information is retrieved. The approach is evaluated using synthetic images deformed by heterogeneous displacement fields. Comparisons show that the introduced modifications lead to lower uncertainties by one order of magnitude in the case of non‐periodic images and displacement field studied. Moreover, first‐order (SO1) and second‐order (SO2) subset‐based Digital Image Correlation algorithms are compared with the ISA. The comparisons herein reveal that the uncertainties of the ISA are 6–9 times smaller than those of the SO1 due to insufficiency of the first‐order shape function for the estimation of heterogeneous displacements, while being slightly smaller than those of the SO2. Moreover, as the image smoothness decreases, the uncertainties of the SO2 deviate from those of the ISA and the exact displacements. The presented approach shows great potentials for challenging applications such as strain measurements at microstructural levels.     

Engineering System Safety Analysis and Synthesis Using the Fuzzy Rule‐based Evidential Reasoning Approach

The main objective of this paper is to propose a framework for modelling, analysing and synthesizing system safety of engineering systems or projects on the basis of a generic rule‐based inference methodology using the evidential reasoning (RIMER) approach. The framework is divided into two parts. The first one is for fuzzy rule‐based safety estimation, referred to as a fuzzy rule‐based evidential reasoning (FURBER) approach. The second one is for safety synthesis using the evidential reasoning approach. In the FURBER framework, parameters used to define the safety level, including failure rate, failure consequence severity and failure consequence probability are described using fuzzy linguistic variables; a fuzzy rule base designed on the basis of a belief structure is used to capture uncertainty and nonlinear relationships between these three parameters and the safety level; and the inference of the rule‐based system is implemented using the evidential reasoning algorithm. Then the following steps involve synthesizing safety at higher levels of an engineering system to integrate all possible causes to a specific technical failure, or estimates made by a panel of experts. The synthesis is also based on the evidential reasoning approach. The final step describes the analysis and interpretation of the final synthesized safety of a system. The above framework has been applied to modelling system safety of an offshore and marine engineering system: the floating production storage offloading (FPSO) system. A series of case studies of collision risk between a FPSO and a shuttle tanker due to technical failure during a tandem offloading operation is used to illustrate the application of the proposed model. Copyright © 2005 John Wiley & Sons, Ltd.     

High‐Performance Photoelectrochemical‐Type Self‐Powered UV Photodetector Using Epitaxial TiO2/SnO2 Branched Heterojunction Nanostructure

TiO₂/SnO₂ branched heterojunction nanostructure with TiO₂ branches on electrospun SnO₂ nanofiber (B‐SnO₂ NF) networks serves as a model architecture for efficient self‐powered UV photodetector based on a photoelectrochemical cell (PECC). The nanostructure simultaneously offers a low degree of charge recombination and a direct pathway for electron transport. Without correcting 64.5% loss of incident photons through light absorption and scattering by the F‐doped tin oxide (FTO) glass, the incident power conversion efficiency reaches 14.7% at 330 nm, more than twice as large as the nanocrystalline TiO₂ (TiO₂ NC, 6.4%)‐film based PECC. By connecting a PECC to an ammeter, the intensity of UV light is quantified using the output short‐circuit photocurrent density (J_sc) without a power source. Under UV irradiation, the self‐powered UV photodetector exhibits a high responsivity of 0.6 A/W, a high on/off ratio of 4550, a rise time of 0.03 s and a decay time of 0.01 s for J_sc signal. The excellent performance of the B‐SnO₂ NF‐based PECC type self‐powered photodetector will enable significant advancements for next‐generation photodetection and photosensing applications.     

基于Pro/E软件悬臂梁的优化设计

以悬臂梁为例,运用Pro/E软件中的Mechanica模块对其进行敏感性分析和优化分析。通过改变悬臂梁截面的长度和宽度尺寸,获得悬臂梁质量和受力方向的位移随尺寸的变化情况;在满足安全的情况下,对悬臂梁截面的长度和宽度尺寸进行了优化,找到了长度和宽度的最佳值,从而提高了产品的设计质量。     

DIC‐based J‐integral evaluation of laser repaired cracks with micro/nanomaterial addition

Cracks generated by a wire electric discharge machining on compact tension specimens are first repaired by high powered laser beam with different weight fractions of nano‐WC added at the crack tip. Digital image correlation method combined with J‐integral theory is used to measure and calculate J‐integrals of the repaired specimens. Fracture properties of the repaired specimens are compared and studied. The residual stress of specimens after being repaired by laser was also studied to analyze the feasibility of J‐integral to evaluate the fracture properties of the repaired parts. It is found that the influence of residual stress can be neglected when calculating J‐integral in a certain region in case of when the residual stress is small. The J‐integral obtained by the digital image correlation measurement is accurate and can effectively evaluate repairing effects. The paper provides guidance for laser repaired cracks with nanomaterial addition and an effective method for the evaluation of repairing effect.