Application study of filamentary composites in a commercial jet aircraft fuselage

A study of applications of filamentary composite materials to aircraft fuselage structure was performed. General design criteria were established and material studies conducted using the 727-200 forebody as the primary structural component. Three design approaches to the use of composites were investigated: uniaxial reinforcement of metal structure, uniaxial and biaxial reinforcement of metal structure, and an all-composite design. Materials application studies for all three concepts were conducted on fuselage shell panels, keel beam, floor beams, floor panels, body frames, fail-safe straps, and window frames. Cost benefit studies were conducted and developmental program costs estimated. On the basis of weight savings, cost effectiveness, developmental program costs, and potential for early application on commercial aircraft, the unaxial design is recommended for a 5-year flight service evaluation program

Cyclic debonding of adhesive joints

Bonded lap joints were manufactured and tested under static and fatigue loading. Specimens were designed to fail in the bondline, and all fatigue tests included monitoring the crack growth to failure. Test specimens included aluminum details joined by two different adhesives. Specimens also included titanium and boron-epoxy details joined by an epoxy laminating resin. Additonal program variables included bondline thickness, adherend and spice plate thickness, specimen width, and specimen fabrication procedure. Adhesive aging was found to be generally detrimental to the lives of most of the specimens bonded with one adhesive system. Adhesive material was found to have a major influence on debond rate. Co-cured titanium/boron-epoxy specimens were found to resist debonding better than specimens fabricated with a sequential cure. Splice plate thickness and test section width were found to have little effect on debond rate. The data also suggested the existence of an optimum bondline thickness

Supporting disabled parents' involvement in their children's education. Good practice guidance for schools

In this guidance you will find the voices of a range of disabled parents describing how good practice in schools has helped them to be involved in their children's education. The guidance is based on the findings of a research project. It is intended for people working in schools, especially heads and teachers seeking to improve parental participation and inclusion. Education policy makers and Inspectorates may find it helpful for informing their reviews of policy and practice. It may also be of interest to disabled parents and the disability voluntary sector. The document contains information about current UK policies on parental involvement and describes the research project which investigated the perceptions of disabled parents. It looks at five different aspects of parental involvement, giving examples of good practice and highlighting suggestions as these emerged from the research project. Key points are summarised in the conclusion, while the appendices include useful resources and contacts

Is service learning a good idea? Data from the National Longitudinal Study of 1988.

Service learning is an integral part of social studies that aims to instill social responsibility among students. According to the National Longitudinal Study of 1988, a significant percentage of high school students participated in community work during the previous two years and that this involvement in community service was greatest in church or church-related groups. However, the survey showed that students favor diversity in their choice of community work and that social action is not their top priority. Furthennore, there is confusion about the difference between service and community learning

Missing Pieces in the Service Learning Puzzle

The increasing popularity in the schools for sponsoring service learning or community service reflects the grave concern that more has to be done to teach youth to participate in a democratic society. The declining voting turnout and the reported low involvement of adults in community groups are often cited as a need for the schools to counter the current apathy and cynicism about government and political leaders. Whether there really is a decline in civic involvement is open to question but the national debate on promoting civic education and social responsibility is reflected in state and local communities requiring students\u27 participation in community service

Quantum paramagnetic ground states on the honeycomb lattice and field-induced transition to N\'eel order

Motivated by recent experiments on Bi$_3$Mn$_4$O$_{12}$(NO$_3$), and a broader interest arising from numerical work on the honeycomb lattice Hubbard model, we have studied the effect of a magnetic field on honeycomb lattice spin models with quantum paramagnetic ground states. For a model with frustrating second-neighbor exchange, $J_2$, we use a Lindemann-like criterion within spin wave theory to show that N\'eel order melts beyond a critical $J_2$. The critical $J_2$ increases with a magnetic field, implying the existence of a field-induced paramagnet-N\'eel transition over a range of $J_2$. We also study bilayer model using a spin-$S$ generalization of bond operator mean field theory. We show that there is a N\'eel-dimer transition for various spin values with increasing bilayer coupling, and that the resulting interlayer dimer state undergoes a field induced transition into a state with transverse N\'eel order. Finally, we study a spin-3/2 model which interpolates between the Heisenberg model and the Affleck-Kennedy-Lieb-Tasaki (AKLT) parent Hamiltonian. Using exact diagonalization, we compute the fidelity susceptibility to locate the Neel-AKLT quantum critical point, obtain the spin gap of the AKLT parent Hamiltonian, and argue that AKLT state also undergoes field-induced Neel ordering.Comment: 8 pages, revised longer version of arXiv:1012.0316. Corrected factor of 2 error in Eq.[16], replotted Fig.[4] and revised the critical $J_c/J_1$ needed to stabilize interlayer dimer state. We thank S. V. Isakov for discussions which uncovered this erro

Residual thermal stress control in composite reinforced metal structures

Advanced composite materials, composed of boron or graphite fibers and a supporting matrix, make significant structural efficiency improvements available to aircraft and aerospace designers. Residual stress induced during bonding of composite reinforcement to metal structural elements can be reduced or eliminated through suitable modification to the manufacturing processes. The most successful method employed during this program used a steel tool capable of mechanically loading the metal component in compression prior to the adhesive bonding cycle. Compression loading combined with heating to 350 F during the bond cycle can result in creep deformation in aluminum components. The magnitude of the deformation increases with increasing stress level during exposure to 350 F

Jane the Virgin and Other Stories of Unintentional Parenthood

In this article, we contrast the roles of intent, function, biology and marriage in establishing legal parenthood, focusing on differences between elite and non-elite reproduction. Central to these differences are the distinctions between intent at the time of conception and birth of a child versus the assumption of parental roles that occurs after birth, and between functional roles that correspond to formal agreements or institutions and those which arise through less formal arrangements. LGBT families have used the concept of intent, as it originated in ART cases, to argue for recognition of families of choice, without either biological ties or the formalities of marriage or adoption. Their success in winning formal legal regulation culminated in the Supreme Court’s embrace of marriage equality in Obergefell v. Hodges, which is likely to increase once again the role of marriage in integrating prebirth intent with legal recognition of parentage for couples in intact unions. At the same time, women have used the creation of families outside of marriage to form alternative families on the basis of a different type of private ordering. Nonelite couples are less likely to reach consistent understandings about their relationships before pregnancy, birth or the assumption of parental roles. Instead, community norms order these understandings. Such norms treat a decision not to marry as part of a system that gives mothers more say vis-a-vis fathers outside of marriage than within it. These relationships are a form of private ordering in that they reflect choices made in accordance with community norms rather than formal institutions or publicly-imposed mandates. These couples, who lack access to the family planning systems and lawyers who help inform elite practices, achieve their greatest autonomy in creating families of choice by staying out of court and often by staying away from each other. The article shows how both of these systems are today under assault: the integration of marriage and elite planning is likely to weaken recognition of families on the basis of intent alone, and reforms are underway to reimpose elite family norms on nonelite parents, undermining their ability to create family terms on their own. This article concludes that the law ought to recognize the variety of arrangements parents adopt rather than apply a single model to all

Ecological considerations for possible Martian biota

Current climatic and geological evidence suggests that, like early Earth, conditions on ancient Mars may also have been favorable for the origin and evolution of life. The primordial atmospheres of the two planets were quite similar, composed primarily of CO2, N2, and water vapor at a total atmospheric pressure of approximately 1 bar. Each of these gases are important for the evolution of biological systems. With the exception of nitrogen, there seems to have been a sufficient supply of the biogenic elements C, H, O, P, and S (CHOPS) on early Mars for life to have evolved. It was postulated that primordial Mars contained only 18 mb of nitrogen in the form of N2 given that only fixed nitrogen is utilized by living systems. Laboratory tests performed at a total pressure of 1 bar and various partial pressures of dinitrogen (pN2 1-780 mb) show that nitrogen fixing organisms grow at pN2's of 18 mb or less, although the biomass and growth rates are decreased. The calcualted in vivo Km's ranged from 46 mb to 130 mb. If organisms adapted on Earth to a pH2 of 780 mb are capable of growing at these low partial pressures, it is conceivable that nitrogen was not the limiting factor in the evolution of life on early Mars

An Unfinished Canvas: Teacher Preparation, Instructional Delivery, and Professional Development in the Arts

Based on surveys, interviews, and secondary data analyses, identifies deficiencies in teacher preparation, instruction, and development in the arts in California, and recommends minimum training requirements and support for professional development