Relating Burst Pressure to Seal Peel Strength In Pouches

This work was aimed at studying the relationship between burst pressure and seal peel strength. Past researchers developed a force balance equation based on the analysis of a force diagram to relate burst pressure to seal strength. The theoretical formula S=P(D/2) (S=Seal Strength, P=Burst Pressure, D=Restraining Plate Gap) has been studied by past researchers with contrasting results. The theoretical formula was tested by varying dwell time to produce seals of varying strength. Pouches were burst tested at each of these dwell times to obtain burst pressures, burst peeling times, and burst locations. Corresponding peel tests were performed with crosshead speeds that were adjusted to match the peeling time of the burst tests. The peel tests were also performed with adjusted gauge lengths to match the plate gap used in inflation burst testing and compression burst testing. The data was analyzed by treating the obtained burst pressures as proxy variables for the unobtainable true burst pressures associated with the pouches that were destroyed during peel testing. Dwell time was used as an instrumental variable, and the two-stage least squares method for parameter estimation was used to estimate the slope of the regression. The estimated slopes of the regressions were compared to the theoretical slope (D/2) for each plate gap using analysis of variance. The results showed that the theoretical relationship suggested by past researchers only worked for a restrained burst test with a plate gap of 0.25in. Empirical equations were developed from the parameter analysis. The empirical equations were used to calculate predicted burst pressures which were then compared to the burst pressures obtained from testing. The percent difference between the two values ranged from 0% to 28%

New records of biting midges of the genus Culicoides Latreille from Mexico (Diptera: Ceratopogonidae)

We provide the first records of six species of biting midges (Diptera: Ceratopogonidae) in the genus Culicoides Latreille from Mexico: C. baueri Hoffman, C. castillae Fox, C. debilipalpis Lutz, C. iriartei Fox, C. leoni Barbosa and C. pusilloides Wirth and Blanton. In addition, C. leopoldoi Ortiz is confirmed from Mexico, and new records are included for 25 other species previously recorded in Mexico: C. arubae Fox and Hoffman, C. blantoni Vargas and Wirth, C. crepuscularis Malloch, C. daedalus Macfie, C. diabolicus Hoffman, C. foxi Ortiz, C. furens (Poey), C. gabaldoni Ortiz, C. haematopotus Malloch, C. hylas Macfie, C. insignis Lutz, C. jamaicensis Edwards, C. luteovenus Root and Hoffman, C. neopulicaris Wirth, C. nigrigenus Wirth and Blanton, C. pampoikilus Macfie, C. panamensis Barbosa, C. paraensis (Goeldi), C. phlebotomus (Williston), C. poikilonotus Macfie, C. pusillus Lutz, C. stigmalis Wirth, and all three species in the C. (Monoculicoides) variipennis complex, C. variipennis (Coquillett), C. occidentalis Wirth and Jones, and C. sonorensis Wirth and Jones

Development of a Design Canvas with Application to First-Year and Capstone Design Courses

The adoption of canvas tools in entrepreneurship and design education is increasing. The Business Model Canvas (BMC), perhaps one of the best-known canvas tools, is the key element of the Lean LaunchPad methodology – a widely utilized approach to business model development. Importantly, using canvases like the BMC supports student learning through a data-driven and iterative process that actively engages students. Another benefit of the canvas approach in an educational setting is they can be used in a preliminary or conceptual design phase, where students can begin to identify and make associations among the key themes of the more complete underlying models used to represent the physical system being envisioned and developed. Because of these benefits, the use of the canvases has led to the development of other canvases with some expressly created for design courses in engineering education settings. A model-based approach for understanding and developing canvases has recently been developed and presented. This approach notes that canvases are high level representations of underlying complex systems. As alluded to above, these complex systems can be business models, but they can also be products, devices, or manufacturing and delivery systems. Briefly, a canvas is constructed by selecting the key themes of systems models that represent the underlying physical systems. Through this representation, canvases can be developed or characterized by identifying and illustrating 1) the underlying system being conceptualized, 2) the model used to represent the system, and 3) the themes selected from the model to be placed on the canvas. Despite these benefits and new approaches to developing canvases, many of the canvases currently being used are better suited for use by experienced and sophisticated users and may be too complex for use by students in underclass or first-year design courses. Using the model based approach described above, a process for developing a canvas for a first-year design course is illustrated in this paper. The process enables an instructor to develop a canvas for their course by examining the learning objectives for the course and identifying the key themes of their learning system and content. Finally, we utilize this process to propose a canvas for a first-year design course

Propuesta para la captación y uso de agua lluvia en las instalaciones de la Universidad Católica de Colombia a partir de un modelo de recolección de agua

Trabajo de InvestigaciónEl presente trabajo se propone la captación y uso de agua lluvia en las instalaciones de la Universidad Católica de Colombia a partir de un modelo físico de recolección de agua, teniendo en cuenta que se puede utilizar como una alternativa para abastecer la demanda de agua, en alguna de las actividades cotidianas en el bloque R de la Universidad Católica de Colombia.INTRODUCCIÓN. 1. GENERALIDADES. 2. PLANIFICACIÓN DEL SISTEMA. 3. DATOS OBTENIDOS SOBRE LA CAPTACIÓN. 4. COMPARATIVO PROPIEDADES FÍSICAS Y QUIMICAS. 5. RUTA CRÍTICA. 6. CONCLUSIONES. 7. RECOMENDACIONES. BIBLIOGRAFÍA - ANEXOSPregradoIngeniero Civi