Damage prediction in cross-plied curved composite laminates

Analytical and experimental work is detailed which is required to predict delamination onset and growth in a curved cross plied composite laminate subjected to static and fatigue loads. The composite used was AS4/3501/6, graphite/epoxy. Analytically, a closed form stress analysis and 2-D and 3-D finite element analyses were conducted to determine the stress distribution in an undamaged curved laminate. The finite element analysis was also used to determine values of strain energy release rate at a delamination emanating from a matrix crack in a 90 deg ply. Experimentally, transverse tensile strength and fatigue life were determined from flat 90 deg coupons. The interlaminar tensile strength and fatigue life were determined from double cantilevered beam specimens. Cross plied curved laminates were tested statically and in fatigue to give a comparison to the analytical predictions. A comparison of the fracture mechanics life prediction technique and the strength based prediction technique is given

An Unquenchable Flame: The Spirit of Protest and the Sit-In Movement in Chattanooga, Tennessee

ABSTRACT The purpose of this thesis is to examine the Sit-in movement in Chattanooga, Tennessee during the early 1960s in the context of a perpetuating tradition of protest in the African American community spanning more than a century. The study will also illustrate how it was a unique episode in the annals of the Civil Rights Movement in that it was strictly orchestrated by high school students without the input or support of adults, yet it has largely been neglected by historians. The research conducted includes oral histories, newspaper clippings, private manuscript collections, books, videos, and periodicals which provide great insight into the minds, motives, and methods of those involved. The study also depicts the galvanizing spirit, ignited by the students, which compelled the community to act and resulted in monumental social changes

Who Supports Voter Identification?

The purpose of this study was to compare and contrast the differences in attitudes from the perspective of African Americans and Caucasian voters in the U.S. In addition, this study examined conscience or unconscious bias toward voter identification laws. In particular, were the effects of voter identification laws viewed through different lens depending on a voter’s ethnic background, social economic status, gender, age, or a voter’s political ideology? I approach this research by examining the results of research conducted by Michael Dawson, Lawrence Bobo, David Wilson, and Paul Brewer. These experts examined both ends of the political spectrum consisting of data from pro-voter id supporters and anti-voter identification supporters. The first hypothesis was the African American community and the cohesiveness race plays a vital role with a focus encompassing civil rights and the perseverance and enhancement of economic equality. The second hypothesis stated that a much higher percentage of Caucasian voters were supportive of voter identification laws. Many of these voters stated that voter identification laws must be implemented in an effort of preventing voter fraud. The third hypothesis was that African American voters should respond to voter identification laws with that of repugnance. Brewer and Wilson’s findings revealed that an overwhelming percentage of voters supported identification laws (78%), 21% opposed identification laws, 48% of voters stated that voter fraud was a major concern, while 43% expressed concern of denying eligible voters the right to vote

Influence of Random Telegraph Noise on Quantum Bit Gate Operation

We consider the problem of analyzing spin-flip qubit gate operation in presence of Random Telegraph Noise (RTN). Our broad approach is the following. We calculate the spin-flip probability of qubit driven by composite pulses, (Constant pulse (C-pulse), Quantum Well pulse (QW-pulse) and Barrier Potential pulse (BP-pulse)) in the presence of RTN using Feynman disentangling method. When composite pulses and RTN act in x-direction and z-direction respectively, we calculate the optimal time to achieve 100% spin-flip probability of qubit. We report the shortcut of spin-flip qubit, which can be achieved by using C-pulse, followed by BP-pulse and QW-pulse. When jumps time in RTN are very fast, tuning of perfect fidelity or spin-flip probability extends to large RTN correlation time. On the other hand, when the jumps in RTN are very slow, the BP-pulse can be used to recover the lost fidelities. Nevertheless, the fidelities of qubit gate operation are larger than 90%, regardless of RTN jumps environments which may be beneficial in quantum error correction. For more general case, we have tested several pulse sequences for achieving high fidelity quantum gates, where we have used the pulses acting in different directions. From the calculations, we find high fidelity of qubit gate operation in presence of RTN is achieved when QW-pulse, BP-pulse and C-pulse act in x-direction, y-direction and z-direction, respectively.Comment: 8 pages, 7 figures. arXiv admin note: text overlap with arXiv:2005.0549

Story Starter:A Tool for Controlling Multiple Virtual Reality Headsets with No Active Internet Connection

Immersive events are becoming increasingly popular, allowing multiple people to experience a range of VR content simultaneously. Onboarders help people do VR experiences in these situations. Controlling VR headsets for others without physically having to put them on first is an important requirement here, as it streamlines the onboarding process and maximizes the number of viewers. Current off-the-shelf solutions require headsets to be connected to a cloud-based app via an active internet connection, which can be problematic in some locations. To address this challenge, we present Story Starter, a solution that enables the control of VR headsets without an active internet connection. Story Starter can start, stop, and install VR experiences, adjust device volume, and display information such as remaining battery life. We developed Story Starter in response to the UK-wide StoryTrails tour in the summer of 2022, which was held across 15 locations and attracted thousands of attendees who experienced a range of immersive content, including six VR experiences. Story Starter helped streamline the onboarding process by allowing onboarders to avoid putting the headset on themselves to complete routine tasks such as selecting and starting experiences, thereby minimizing COVID risks. Another benefit of not needing an active internet connection was that our headsets did not automatically update at inconvenient times, which we have found sometimes to break experiences. Converging evidence suggests that Story Starter was well-received and reliable. However, we also acknowledge some limitations of the solution and discuss several next steps we are considering

LNCS

Systems ought to behave reasonably even in circumstances that are not anticipated in their specifications. We propose a definition of robustness for liveness specifications which prescribes, for any number of environment assumptions that are violated, a minimal number of system guarantees that must still be fulfilled. This notion of robustness can be formulated and realized using a Generalized Reactivity formula. We present an algorithm for synthesizing robust systems from such formulas. For the important special case of Generalized Reactivity formulas of rank 1, our algorithm improves the complexity of [PPS06] for large specifications with a small number of assumptions and guarantees

Making Buildings Part of the Climate Solution by Enforcing Aggressive Commercial Building Codes

This paper examines the impact of an aggressive commercial building codes policy in the United States. The policy would require both new construction and existing buildings that undergo major modifications to comply with higher building shell efficiency and more stringent equipment standards similar to the latest versions of the ASHRAE 90.1 Standard. Using the Georgia Tech version of the National Energy Modeling System (GT-NEMS), we estimate that the building codes policy could reduce the energy consumption of commercial buildings by 0.94 Quads in 2035, equal to 4% of the projected energy consumption of commercial buildings in that year. In the four targeted end-uses – space heating and cooling, water heating and lighting – estimated energy consumption would be 17%, 15%, 20% and 5% less than the Reference case forecast in 2035, respectively. The reduction of electricity and natural gas prices along with the consumption decline could save commercial consumers $12.8 billion in energy bills in 2035 and a cumulative$110 billion of bill savings between 2012 and 2035. The environmental benefits of the policy could also be significant. In 2035, 47 MMT of CO2 emissions could be avoided, generating cumulative benefits of $17 billion by 2035. The estimated benefit-cost ratio of this policy within the commercial sector is 1.4, with a resulting net benefit of$59 billion. The positive spillover effect of this policy would lead to an even higher economy-wide benefit-cost ratio

Moisture performance of sealed attics in the mixed-humid climate

Oak Ridge National Laboratory studied 8 homes in the mixed-humid climate, 4 with vented attics and 4 with sealed attics. ORNL wanted to understand the moisture performance of the sealed attic and how it affected the interior environment. We found that the attic and interior of sealed attic homes were more humid than the attic and interior observed in vented attic homes. This is due to the lack of ventilation in the sealed attic. Historically attics have been vented to dehumidify the attic and interior of the home. A sealed attic design greatly reduces the venting potential and thus this drying pathway and can cause elevated interior moisture over a vented attic home. Despite the elevated attic and interior moisture in the sealed attic homes, so far no mold or material degradation has been found. The roof sheathing moisture content has stayed below 20%, indicating low potential for material degradation. Also the relative humidity at the roof sheathing has stayed within the ASHRAE 160 design criteria except for a short time during the 2011/2012 winter. This was due to a combination of the sealed attic design (minimal venting to the outside) and the duct work not being operated in the attic which usually provides a dehumidification pathway. It was also found that when the humidity was controlled using the HVAC system, it resulted in 7% more cooling energy consumption. In the mixed-humid climate this reduces the cost effectiveness of the sealed attic design as a solution for bringing ducts into a semi-conditioned space. Because of this we are recommending the other alternatives be used to bringing ducts into the conditioned space in both new construction and retrofit work in the mixed-humid climate

Component and System Level Research of Variable Capacity Heat Pumps

With high cooling and heating efficiencies, variable capacity heat pumps are an emerging technology with the potential to substantially reduce the energy required for the heating and cooling of residential structures. In order for them to make an impact in this area, they must first be more widely accepted by the American consumer as an alternative to less expensive single speed systems, This acceptance, in large part, is based upon a greater understanding of how these systems perform in real world tests. To this end, this study will evaluate the energy consumption and efficiencies of four variable capacity heat pumps installed in two unoccupied research homes in Farragut, a suburb of Knoxville, Tennessee, one occupied home in downtown Knoxville, and one occupied home in Duluth, Georgia