Measure Guideline: Condensing Boilers - Control Strategies for Optimizing Performance and Comfort in Residential Applications

The combination of a gas-fired condensing boiler with baseboard convectors and an indirect water heater has become a common option for high-efficiency residential space heating in cold climates. While there are many condensing boilers available on the market with rated efficiencies in the low to mid 90% efficient range, it is imperative to understand that if the control systems are not properly configured, these heaters will perform no better than their non-condensing counterparts. Based on previous research efforts, it is apparent that these types of systems are typically not designed and installed to achieve maximum efficiency (Arena 2010). It was found that there is a significant lack of information for contractors on how to configure the control systems to optimize overall efficiency. For example, there is little advice on selecting the best settings for the boiler reset curve or how to measure and set flow rates in the system to ensure that the return temperatures are low enough to promote condensing. It has also been observed that recovery from setback can be extremely slow and, at times, not achieved. Recovery can be affected by the outdoor reset control, the differential setting on the boiler and over-sizing of the boiler itself. This guide is intended for designers and installers of hydronic heating systems interested in maximizing the overall system efficiency of condensing boilers when coupled with baseboard convectors. It is applicable to new and retrofit applications

La interpretación de Kant de Fernando Montero Moliner.

Sin resume

A Longitudinal Comparison of Parent and Child Influence on Sports Participation

Drawing on expectancy-value theory, this study examines children’s motivational attributes and parental influences on how children spend their leisure time in middle childhood and adolescence. Specifically, the study examined if parent encouragement and beliefs (i.e., perceived importance of sports and perceived child ability) and child motivation (expectancy and value for sports) are predictive of sports participation over the course of middle childhood and adolescence. Parent and child reports are compared using data from the Childhood and Beyond (CAB) longitudinal study. Findings reveal that parent beliefs and encouragement and child motivation were positively associated with sports participation in middle childhood. Both parental influences and children’s motivation measured in middle childhood were predictive of time spent participating in adolescence. However, only parent influences were predictive of whether the child continued to participate in sports in adolescence

Measuring What Matters Most

An argument that choice-based, process-oriented educational assessments are more effective than static assessments of fact retrieval. If a fundamental goal of education is to prepare students to act independently in the world—in other words, to make good choices—an ideal educational assessment would measure how well we are preparing students to do so. Current assessments, however, focus almost exclusively on how much knowledge students have accrued and can retrieve. In Measuring What Matters Most, Daniel Schwartz and Dylan Arena argue that choice should be the interpretive framework within which learning assessments are organized. Digital technologies, they suggest, make this possible; interactive assessments can evaluate students in a context of choosing whether, what, how, and when to learn. Schwartz and Arena view choice not as an instructional ingredient to improve learning but as the outcome of learning. Because assessments shape public perception about what is useful and valued in education, choice-based assessments would provide a powerful lever in this reorientation in how people think about learning. Schwartz and Arena consider both theoretical and practical matters. They provide an anchoring example of a computerized, choice-based assessment, argue that knowledge-based assessments are a mismatch for our educational aims, offer concrete examples of choice-based assessments that reveal what knowledge-based assessments cannot, and analyze the practice of designing assessments. Because high variability leads to innovation, they suggest democratizing assessment design to generate as many instances as possible. Finally, they consider the most difficult aspect of assessment: fairness. Choice-based assessments, they argue, shed helpful light on fairness considerations

Comportamiento a la flexión y absorción de humedad en placas de aglomerado y polipropileno reciclado

La fabricación de placas aglomeradas tiene dos inconvenientes importantes: el consumo de madera virgen y la emisión de VOC’s (compuestos orgánicos volátiles), localizados en el adhesivo utilizado, que tienen consecuencias ambientales ampliamente documentadas. Para mitigar estos efectos, se han realizado experiencias de conformación de placas sustituyendo en parte la madera virgen por material reciclado, el cual elimina además la necesidad de utilizar adhesivos. Este trabajo muestra los resultados obtenidos en los ensayos de flexión y de absorción de humedad de placas hechas a escala piloto, con distintas proporciones de madera y polipropileno reciclado, y su comparación con los valores de placas comerciales de un espesor semejante. Estos resultados resultan alentadores, ya que si bien presentan amplia variabilidad dada su conformación a escala no industrial, con las placas conformadas con material reciclado se están alcanzando valores de resistencia a la flexión cercanos a los comerciales en los ensayos realizados, y en la absorción de humedad los resultados son mejores que en las comerciales.Fil: Rivarola, A.. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Rojo, L.. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; ArgentinaFil: Arena, Alejandro Pablo. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentin

Measuring What Matters Most

An argument that choice-based, process-oriented educational assessments are more effective than static assessments of fact retrieval.If a fundamental goal of education is to prepare students to act independently in the world—in other words, to make good choices—an ideal educational assessment would measure how well we are preparing students to do so. Current assessments, however, focus almost exclusively on how much knowledge students have accrued and can retrieve. In Measuring What Matters Most, Daniel Schwartz and Dylan Arena argue that choice should be the interpretive framework within which learning assessments are organized. Digital technologies, they suggest, make this possible; interactive assessments can evaluate students in a context of choosing whether, what, how, and when to learn.Schwartz and Arena view choice not as an instructional ingredient to improve learning but as the outcome of learning. Because assessments shape public perception about what is useful and valued in education, choice-based assessments would provide a powerful lever in this reorientation in how people think about learning.Schwartz and Arena consider both theoretical and practical matters. They provide an anchoring example of a computerized, choice-based assessment, argue that knowledge-based assessments are a mismatch for our educational aims, offer concrete examples of choice-based assessments that reveal what knowledge-based assessments cannot, and analyze the practice of designing assessments. Because high variability leads to innovation, they suggest democratizing assessment design to generate as many instances as possible. Finally, they consider the most difficult aspect of assessment: fairness. Choice-based assessments, they argue, shed helpful light on fairness considerations

Antiferromagnetic phase of the gapless semiconductor V3Al

Discovering new antiferromagnetic compounds is at the forefront of developing future spintronic devices without fringing magnetic fields. The antiferromagnetic gapless semiconducting D03 phase of V3Al was successfully synthesized via arc-melting and annealing. The antiferromagnetic properties were established through synchrotron measurements of the atom-specific magnetic moments, where the magnetic dichroism reveals large and oppositely-oriented moments on individual V atoms. Density functional theory calculations confirmed the stability of a type G antiferromagnetism involving only two-third of the V atoms, while the remaining V atoms are nonmagnetic. Magnetization, x-ray diffraction and transport measurements also support the antiferromagnetism. This archetypal gapless semiconductor may be considered as a cornerstone for future spintronic devices containing antiferromagnetic elements.Comment: Accepted to Physics Review B on 02/23/1