Joseph P. Fuehne

Examination of Accuracy in the Assessment of Gastric Residual Volume A Simulated, Controlled Study

BACKGROUND Increased gastric content from enteral nutrition intolerance is thought to place patients at risk for pulmonary aspiration. Although considered a questionable practice, blind gastric tube aspiration is the most common approach to measure gastric content. This simulated study evaluated the accuracy of residual volume (RV) assessment via tube aspirations made from known volumes by controlling the syringe pull technique, feeding tube properties, fluid viscosity, and placement of tubes in the fluid. MATERIALS AND METHODS This study was conducted in a metrology laboratory. Aspirates were obtained using a force measurement test system to control force of the syringe pull technique using 3 different procedures (slow 10 inches per minute [ipm], intermittent 10 ipm, and fast 40 ipm). Four different feeding tubes, 10 Fr and 18 Fr, each made of polyurethane and polyvinyl chloride, were placed in varying depths of 100 mL of either water or formula. The effect of fluid viscosity was also examined. RESULTS Overall, 108 RVs were analyzed using a force measurement test system. Actual content of RV was underestimated 19% on average and varied across tube size and viscosity. Intermittent and slow syringe pull techniques yielded greater aspirate quantities, although neither technique aspirated the full amount of volume available. The 10 Fr feeding tubes yielded larger RVs in more viscous fluid, yet the 18 Fr tubes performed better with fluids of lower viscosity. CONCLUSIONS Based on this simulation, RV assessment does not accurately reflect the total volume of the contents available and, therefore, the clinical utility of this assessment should be further investigated.

Finite Element/Penalty Function Method for Computing Stresses near Debonds

A shear deformable, finite element penalty formulation is developed for predicting stress fields, particularly interlaminar shear and normal stresses, in thick composite laminates and near a delaminated free edge in a laminated plate. A fully three-dimensional 20-noded finite element is coupled with the feature of integrating the equilibrium equations to compute interlaminar shear stresses and characterize three-dimensional stress fields. As an alternative to using the constitutive equations, the integration of the equilibrium equations provides an improved variation of interlaminar shear stresses through the thickness. Penalty functions are utilized in the formulation to represent continuity or discontinuity between layers of elements. Proficient use of these penalty functions allows simple definition of critical interfaces in a composite laminate where delamination has occurred. The flexibility of the formulation permits the consideration of different sizes of debonds without having to create a new model. In this paper, thick composite laminates are considered to demonstrate the improved variation of interlaminar shear stresses computed by integrating the equilibrium equations. Finally, a [0 deg/90 deg/0 deg] undelaminated plate subjected to uniform axial extension is compared with the same geometry containing a free-edge debond, one ply thickness in depth.

Embedding Multiple Assessments in Classroom Activities

The Mechanical Engineering Technology program of Purdue University at Columbus/Southeast Indiana is a small program with only two full-time faculty and typically has 4-8 graduates per year. In preparing for its first ever ABET accreditation evaluation in the fall of 2005, the faculty conducted a survey of graduates from the last three years and received nine responses. Such a small response contributed to the concern that this method of assessment might not provide much useful data regarding assessment of program outcomes and objectives. As a result of this and limited resources, the faculty of the MET program in Columbus focused their efforts on direct assessment of program outcomes by using classroom assignments, lab reports and exam questions. An example of an embedded assessment utilized by the MET faculty is a laboratory report. The Mechanical Engineering Technology program consists of many classes that have laboratory activities. The rubric used for lab reports is a fifteen part rubric that varies from 1 to 4. Lab reports are assessed for spelling/grammar, participation, calculations, appearance, analysis, summary, conclusions and drawings/diagrams among other categories. Assessments can be made of technical content (program outcome (PO 1), verbal communications including both written content and graphical communications (PO 3), experimental understanding and teamwork. While these assessments are useful for gauging learning and are used in the MET program continuous quality improvement process, they also make grading considerably easier. A two-page form was also developed which summarized the assessment points for each program outcome. The first page of the form includes the mission statements of Purdue University, the MET program objectives, the MET program outcomes, the core learning objectives of the particular course in which the assessment is performed and the details of the assessment point. These details include the specific core learning objective, the applicable program outcome and the rubric for the assessment. The second page of the form includes the results of the assessment, those teaching techniques that the faculty member wants to retain and those that he wants to change.Copyright

Transverse Stress Predictions for Thin-to-Thick Composite Structures: Shear Deformable Finite Element Penalty Formulation

A shear deformable finite element formulation for laminated composite plate and shell structures is extended so that thin as well as thick geometries can be studied. This is accomplished by a specially constructed layering of elements in the ‘thickness’ direction. Adjoining layers are mathematically coupled at common interlaminar boundaries by use of a penalty parameter formulation. Since each element has simply midsurface nodal points at which displacements/rotations are prescribed, constraint equations serve to relate motion at layer midsurfaces to motion at layer interfaces. Continuity in each interface, i.e. between two layers, is represented by a set of three penalty parameters. Two of these parameters provide continuity of interlaminar shear stresses across the interface, while the third parameter provides continuity of interlaminar normal stress. In modelling actual structures, the degree of layering as well as specification of the penalty parameters can be extensively varied to account for changes in geometry, geometric discontinuities and the like.

A shear deformable, doubly curved finite element for the analysis of laminated composite structures

Abstract A doubly-curved, shear-deformable finite element is developed for the analysis of laminated composite structures. The Kirchhoff hypothesis is relaxed to allow for shear deformations; as a result, three independently prescribed rotations as well as three displacements are specified at each of the eight nodes of the element. The constitutive equations are utilized to calculate the in-plane stresses for each layer of the laminated structure. In order to establish an appropriate variation through the thickness, the transverse shear stresses are found by integrating the equilibrium equations for each layer. An integration procedure using a finite difference approach is performed to evaluate the transverse shear stresses. Excellent results have been achieved for a three-layered, helically-wound cylinder with simply-supported and clamped ends.

Incorporating Ethics and Lifelong Learning Into a Mechanical Engineering Technology Program

The Mechanical Engineering Technology program at Purdue University at Columbus/SE Indiana hosted ABET evaluators for the first time in the fall of 2005. Both the program objectives and outcomes of the MET program contain elements of ethical behavior and lifelong learning. These elements are simply reflective of the importance put on ethics and lifelong learning by the Accreditation Board for Engineering and Technology programs in the TC2K criteria. This work will describe the use of test cases and specific exercises that are incorporated in classes during the first semester and final semester of the two-year Associate of Science program. In-class surveys of students are also used to examine the ethical and professional behavior of students. The test cases are presented in multiple parts with students required to finish their answers to the questions from the first part before they get to see the second part. The same procedure is followed for the remaining parts of the test case. Each part of the test case also includes comments from a panel of experienced engineers who lend their expertise to the situation. These comments are shared with the students. For lifelong learning, the students are presented with a short lecture on the value of lifelong learning that includes relevant data and facts related to lifelong learning. After this, an assignment is given that asks the students to learn about how to design a container for nuclear waste storage and ship it to the proper waste disposal location. Other assignments are mentioned and can be used in a similar manner.Copyright

Using a foundation grant to introduce technology through the local K-12 school system

An element of Purdue Universitys strategic plan involves encouraging technology education through K-12 outreach programs. Consistent with this mission, the authors applied for and received a grant from the Decatur County (Indiana) Community Foundation to deliver math and science-based workshops using LEGOtrade models. As recommended by the foundation, the workshops are delivered through the local school systems to a target group of advanced fourth through sixth graders at the public and private schools of Decatur County. Workshops include having students construct simple machines using LEGOtrade bricks and air power elements. In order to stimulate their thinking, the students are asked to complete worksheets that require simple measurements and calculations as well as recording observations that stimulate critical thinking. Pre- and post-tests are administered as assessment instruments to measure student learning. Results from the assessment instruments are presented with particular attention to gender and age differences

Virtual Lab Activities for a Distance Course in Fluid Power

Virtual lab activities utilizing simulation software are gaining in popularity and importance. Simulation software can be purchased in sufficient quantities to allow every student in a class to perform lab activities rather than doing physical labs with limited equipment and a team approach, providing uncertainty as to who is really doing the work. Another advantage would be using the software across several locations throughout a region and pairing it with software like Adobe Connect or two-way video in some distance education format. Students in multiple locations can connect via computer and can perform lab activities in synchronous or asynchronous sessions. Actual physical lab activities could be included in the course on a limited basis to accommodate students from several locations. This work will investigate simulation software available for use with fluid power and discuss strategies for incorporating into appropriate classes.Copyright

Developing a System Approach for the Engineering Technology Classroom

Traditional Engineering Technology classes treat various topics in isolation without ever considering a complete system. Students may learn about electrical components such as switches, fuses, solenoids, and other components in a class that never discusses how they are used in real devices and systems. Not knowing how these components connect to real systems, students have a difficult time knowing how these components fail and how that failure is manifested in the system. The system approach begins by looking at the complete system and understanding its objective. Using a solenoid as an example, students can see what the function of the solenoid is to the function of the system. They also will see what happens to the system if the solenoid doesn’t function and how the entire process is affected. At this point, the operation, functionality, properties and characteristics of solenoids are investigated. Students learn how a solenoid works, how to make measurements that would assist in troubleshooting a solenoid, and which individual parts of the solenoid could be responsible for a failure. The system approach is ideally modeled as a circle which starts and ends by looking at the system and features the details in between. Some might argue that there isn’t time in a class plan for this extra work but after doing this once or twice, the process goes rather quickly as students become familiar with it. This work will provide details of implementing this in the classroom and will provide more examples.Copyright

Integrating Mechatronics Into an Engineering Technology Curriculum

Mechatronics can be defined as a science combining mechanical elements, electrical elements, fluid power, and computer programming in a complex system to accomplish a certain task, such as the assembly of a hydraulic directional control valve. In the Mechanical Engineering Technology curriculum at Purdue University in Columbus, Indiana, all of these topics are addressed in individual classes but rarely are they considered together in a complex system. Mechatronics has been the vehicle to allow students to investigate a complete system, rather than simply individual elements or topics. In particular, a system that utilizes seven different machines, each controlled by programmable logic controllers, to assemble a directional control valve is employed to present these topics to students. In the absence of a specific class that might be called Mechatronics (a new class is being considered), the operations of the directional control valve assembly are being integrated into several classes including a first-semester class as a way to demonstrate some real-world manufacturing activities to new students who might otherwise become disinterested due to the math, English, and other related courses in the first year. As such, the mechatronics equipment serves as a retention tool. Additionally, the mechatronics system is used in a basic electricity class, a fluid power class, a machine elements class and, finally, an instrumentation and process control class, where all the individual elements are considered in the system. All of these integrating elements are considered in this work.Copyright