1,374 research outputs found
The Rate of Precipitation of Copper Aluminide in the Silver Rich Silver-Copper-Aluminum Alloys
In order to determine the best annealing temperature at which to age-harden the alloys, hardness tests on speciÂmen annealed for different lengths of time at different temperatures were made
Space acceleration measurement system triaxial sensor head error budget
The objective of the Space Acceleration Measurement System (SAMS) is to measure and record the microgravity environment for a given experiment aboard the Space Shuttle. To accomplish this, SAMS uses remote triaxial sensor heads (TSH) that can be mounted directly on or near an experiment. The errors of the TSH are reduced by calibrating it before and after each flight. The associated error budget for the calibration procedure is discussed here
Carbon Credits
A carbon credit is an allowance or offset equal to one metric ton of carbon dioxide (C02) or other greenhouse gas (GHG) equivalent calculated in tons of C02. Carbon markets allow individuals, companies, or states to finance emissions reductions in other locations, for example, through projects that create or promote renewable energy, energy efficiency, or reforestation, as a means to lower their own carbon footprint. Trade of carbon credits within compliance and voluntary markets is a multibillion-dollar enterprise that makes up a cornerstone of international efforts to combat climate change. Buying and selling emissions allowances often means that mitigation can be achieved at lower costs
Renewable Energy and Human Rights Violations: Illustrative Cases from Indigenous Territories in Panama
Local implementation of international climate policies is frequently obscure. The objective of our research is to unpack the black box of carbon offsetting as it is being conducted in Latin American indigenous territories. Our two case studies of renewable energy projects under construction in Naso and Ngobe villages in western Panama show that carbon offsets in oppressive societies have the potential to cause social harm. Our cases illustrate processes of green authoritarianism, spatial control, and social restructuring. The private developers constructing the Chan 75 and Bonyic dams did not follow international standards for free, prior, and informed consent, and state agencies reinforced private rights with physical violence. As the hydro developers await decisions on their applications for verification under the Clean Development Mechanism (COM), we recommend COM procedural reforms to assure respect for human rights, including the special rights codified in the 2007 UN Declaration on the Rights of Indigenous Peoples. If not, project developers could use low-carbon objectives to justifY social oppression
Recommended from our members
Late Cenozoic Geomorphic Evolution of the Texas Panhandle and Northeastern New Mexico: Case Studies of Structural Controls of Regional Drainage Development
Salt dissolution has affected parts of the Upper Permian Salado, Seven Rivers, San Andres, Glorieta, and upper Clear Fork Formations beneath the Pecos River Valley in eastern New Mexico and beneath the Canadian River Valley and the Rolling Plains of the Texas Panhandle. Extensive dissolution of the salts of the Salado and Seven Rivers Formations has also occurred beneath the Southern High Plains. The cumulative thickness of salt lost to dissolution exceeds 150 m (500 ft) along the western, northern, and eastern margins of the Palo Duro Basin.
Dissolution and subsidence occurred during the deposition of the Tertiary Ogallala Formation, but Ogallala deposition kept pace with subsidence. Following the end of Ogallala deposition in the late Pliocene, surface subsidence resulted in lacustrine basins along trends of relatively rapid dissolution. Preserved lacustrine sediments contain Blancan faunas, confirming minimum late Pliocene ages for the basins.
Continued subsidence along trends of relatively rapid dissolution during the late Tertiary and early Quaternary resulted in a series of basins that diverted many of the streams flowing southeasterly across the Southern High Plains. As a result of subsidence, the headwaters of the ancestral Brazos River were diverted during the middle Pleistocene from a southeasterly drainage through the Portales paleovalley to a southerly drainage through the Pecos Valley. The present-day headwaters of the Canadian River are probably a former tributary of the Pecos-Portales-Brazos system that was diverted to the northeast along a subsidence trend caused by dissolution during the late Pliocene or early Quaternary.Bureau of Economic Geolog
Role of the Dental Community in HPV Vaccination Promotion
Introduction. With increasing awareness that human papillomavirus (HPV) can cause oropharyngeal cancer (OPC), dental providers may play an important role in promoting HPV vaccination and preventing cancer. Our goal was to assess knowledge and current HPV vaccine counseling practices among Vermont dentists and dental hygienists to identify potential targets for state-level interventions to increase vaccine coverage.
Methods. We developed a survey to assess knowledge, beliefs, practices and barriers regarding HPV vaccination, and distributed it via email to practicing Vermont dentists and dental hygienists. Free responses were analyzed using a coding framework generated from three key informant interviews.
Results. 90% of providers believe it is important for them to play an “active role” in their patients’ general medical care, yet only 50% believe it is their responsibility to recommend HPV vaccine. Only 50% feel knowledgeable enough to recommend the vaccine. 78.6% of providers rarely discuss HPV vaccination with their age-appropriate patients, and 82% rarely recommend the vaccine. When asked to name the biggest barrier against recommending vaccination, providers named the following factors most frequently: “not responsibility of dental provider” (27%); lack of confidence in knowledge (19%); time constraints (14%); and parent philosophical/religious opposition (11%).
Discussion. Because dentists and dental hygienists care for a broad pediatric population across the state, dental communities may be poised to play an expanded role in Vermont’s efforts to improve its HPV vaccination coverage. Our study identifies several potential areas for provider-focused interventions, which include educating providers about the HPV vaccine and reducing significant barriers against recommending.https://scholarworks.uvm.edu/comphp_gallery/1266/thumbnail.jp
Battery Degradation Modeling For Vehicle Applications
Fuel efficiency is a fundamental part of the automotive industry and its impact on the global environment. This is a direct result of the Corporate Average Fuel Efficiency (CAFE) standards imposing a 70% improvement of fuel efficiency on all light duty line-ups between 2014 and 2025. To achieve such an improvement, automotive manufacturers will need to electrify their powertrains. Lithium ion battery technology has emerged as a leading component in electrification with the development of hybrid, plug-in hybrid, and battery electric vehicles. Therefore, the design and sizing of these battery packs must be accurate.
The correct design and sizing of a battery pack must account for the lifetime of the battery. In plug-in hybrid and battery electric vehicles, the battery pack is directly responsible for the all-electric range of that vehicle. As the battery ages, this range decreases. Convention has been to size the battery to account for a 20% loss in electric range; however the degradation rate varies from vehicle to vehicle depending on the driver’s behavior. The convention can lead to severely oversized battery packs, which decreases operational efficiencies, and increases vehicle mass, and greenhouse gas emissions. Therefore, it is important to consider realistic driver behavior when sizing the battery pack.
The A123 AMP20 pouch battery was selected for the degradation analysis. A semi-empirical single particle battery degradation model was developed in MATLAB Simulink for the AMP20. 2 mAh half-cell coin cells were built from the AMP20 materials and cycled at C/50 to obtain a close approximation of the electrode open circuit potentials at various states of lithiation. The open circuit potentials were used in the single particle model. Additionally, rate capability tests and degradation cycling are conducted on the AMP20 to fit the single particle model parameters. The LFP particle resistance was empirically fit and depended upon the state of lithiation and whether the battery was charging or discharging.
A sensitivity analysis of the Tafel equation was performed to determine that the parasitic current density was a function of the negative electrode potential, the solid electrolyte interface (SEI) film resistance, and the negative electrode current density. The operational state-of-charge (SOC), the depth-of-discharge (DOD), the history of the battery, and the battery current are all vehicle parameters that impact the parasitic current density. For low current operations, a change in the SOC will yield the largest change in parasitic current density. For high current operation of a fresh battery, a change in the SEI resistance yields the largest change in parasitic current density; while an aged battery yields the largest change in parasitic current density from a change in battery current. It was determined that the SEI resistance did not prove to be a significant factor affecting battery degradation. It was also determined that a long charging time, a high operational SOC, a large DOD, and aggressive current demand are primary factors that increase battery degradation.
Simulations on the single particle model were conducted to assess the degradation rates of common Environmental Protection Agency (EPA) drive cycles. The simulation results showed that the degradation rate significantly depends upon the duty cycle. The UDDS cycle degraded the battery at a dramatically faster rate than the US06 and HWFET cycles for 80% initial SOC, 17.41, 3.08, and 4.64 (µAh Li+)(Ah Processed)^-1; at 50% initial SOC, 7.04, 1.79, and 2.14 (µAh Li+)(Ah Processed)^-1; and at 20% initial SOC, 1.85, 0.46, and 0.54 (µAh Li+)(Ah Processed)^-1. It was concluded that the operational SOC, the charging time, and the current demand are the primary factors that affect the degradation rate of a duty cycle. Further simulations were performed with 1C charging after the duty cycle to return the operational SOC to its initial value and to account for the duty cycle DOD. Accounting for the duty cycle DOD increased degradation by between 47% and 86%; providing evidence that the DOD is an important factor of degradation.
An analysis of battery degradation on realistic driving behaviour was conducted using four sets of real-world driving data of Nissan Leaf drivers taken from CrossChasm Technologies Inc.’s real-world driving database. The charging time, mean operational SOC, mean DOD, and current demand were used to hypothesize that Driver 1, Driver 3, Driver 2, and Driver 4 would have the highest to lowest degradation over an eight year period. The simulation results on the driver’s duty cycles agreed with the hypothesis, producing 5.51%, 5.17%, 4.16%, and 0.75% capacity fade, respectively. Therefore the conclusions made from the sensitivity analysis and the EPA study are applicable for real-world data.
The key finding from this work is that battery degradation depends on the duty cycle. Specifically, the charging time, the operational SOC, the DOD, and the current demand are all factors affecting battery degradation. Ultimately, the battery degradation rate is unique for each driver, depending on those factors
Increasing Patients\u27 Understanding of Prescribed Medication Adherence
The cost of healthcare in the United States has increased due to growing numbers of patients who live with chronic health problems, such as heart disease. The cost of healthcare is compounded by the cost in terms of complications of cardiovascular disease secondary to medication non-adherence. Education about medication use and adherence, safety, and side effects was needed for patients in a cardiovascular unit to improve adherence to medications as prescribed. Results of a health care provider (HCP) and nursing staff needs assessment provided by the site showed the need for improved cardiovascular medication education. The project focused question asked if cardiovascular patient medication education provided to HCPs and nursing staff would be incorporated into practice by the HCPs and nursing staff. The purpose of the project was to improve the education provided to patients by the HCPs and nursing staff. A literature review provided content for the educational program. Strategies to promote adherence and medication safety and a patient education worksheet were presented with guidance on implementation. Post education qualitative results from HCPs and nursing staff showed that the sheet was implemented and helpful with educating cardiovascular patients. This project promotes positive social change by the implementation of a patient education program that may improve patient education and adherence to cardiovascular medications. As a result, improved adherence to medications may reduce patient and healthcare related costs long term
Resolution of the mystery of counter-intuitive photon correlations in far off-resonance emission from a quantum dot-cavity system
Cavity quantum-electrodynamics experiments using an atom coupled to a single
radiation-field mode have played a central role in testing foundations of
quantum mechanics, thus motivating solid-state implementations using single
quantum dots coupled to monolithic nano-cavities. In stark contrast to their
atom based counterparts, the latter experiments revealed strong cavity
emission, even when the quantum dot is far off resonance. Here we present
experimental and theoretical results demonstrating that this effect arises from
the mesoscopic nature of quantum dot confinement, ensuring the presence of a
quasi-continuum of transitions between excited quantum dot states that are
enhanced by the cavity mode. Our model fully explains photon correlation
measurements demonstrating that photons emitted at the cavity frequency are
essentially uncorrelated with each other even though they are generated by a
single quantum dot.Comment: 5 pages, 4 figure
- …