2,953 research outputs found
ANALYZING EMERGENT BEHAVIOR OF SUPPLY CHAINS FOR PERSONAL PROTECTIVE EQUIPMENT IN RESPONSE TO COVID-19
The novel coronavirus (COVID-19) revealed weaknesses in supply chains of companies that produce personal protective equipment (PPE), resulting in nationwide shortages. A government-industry collaborative platform between the National Institute for Standards and Technology (NIST) and Helpful Engineering is under development to act as an exchange for material and equipment at each level of the supply chain. The intent of this is to create an online agile production platform (APP) for PPE. There is a need to proactively limit negative interactions with the APP. The creators of the APP constrain bad behavior or abuse of the system using a "bottom up" approach of coding requirements. In tandem, a "top down" approach of the system is modeled using Monterey Phoenix, a behavioral modeling platform. Stakeholders and processes are modeled to show different permutations of interactions. Impossible scenarios are removed with model constraints. The remaining traces are analyzed for emergent behavior and compared with the constraints programmed into the model. Findings of this research include unexpected emergent behavior in two scenarios. One scenario explored delivered quality to the customer, and analysis exposed a gap that allowed counterfeit parts into the APP. The other scenario explored how the APP managed the supply chain. Weaknesses that allowed missed inspections to pass bad parts were also found. The models developed will drive changes that increase confidence in the APP.Outstanding ThesisCivilian, Department of the NavyApproved for public release. Distribution is unlimited
The Quasimonotonicity of Linear Differential Systems - The Complex Spectrum
The article of record as published may be located at http://dx.doi.org/10.1080/00036810108840984The method of vector Lyapunov functions to determine stability in dynamical systems requires that the comparison system be quasimonotone nondecreasing with respect to a cone contained in the nonnegative orthant. For linear comparison systems in Rn with real spectra, Heikkilᄄa solved the problem for n = 2 and gave necessary conditions for n > 2. We previously showed a su_cient condition for n > 2, and here, for systems with complex eigenvalues, we give conditions for which the problem reduces to the nonnegative inverse eigenvalue problem
The effects of seismic blasting on shallow water wells and aquifers in western North Dakota
Seismographic petroleum exploration throughout North Dakota has generated concern over the effects of blasting on groundwater supplies and wells. A preliminary investigation revealed complaints alleging declining productivity and decreased water quality in regions where coal aquifers are extensively used. Unplugged shotholes were frequently cited as a source of problems.
Experimental results indicate that changes due to blasting occur within long term physical the aquifers rather than in specific water wells. Pumping tests conducted in a sand and coal aquifer system showed no apparent physical effects when shots were detonated one quarter mile away from the pumping wells. Shots 500 feet distant resulted in no permanent effects. Shots 100 feet or closer increased the yield from wells finished in the sand aquifer and decreased the yield from the coal aquifer. Fracturing of the poorly indurated sandstone aquifer is suggested as a mechanism for the increase. Collapse of fractures is suggested as the failure mechanism in the coal aquifer. Well casings remained intact after 25 pound charges were detonated as close as 10 feet from a well screen. Currently available methods for evaluating pump test data do not adequately were also provided. Rick Nelson, Environmental Engineer, served as the Health Department liasion. Rod Reetz and Ken Kary of the North Dakota State Department of Health Laboratories were especially helpful in expediting the sample analyses in the face of staggering backlogs of samples from other sources.
The North American Coal Corporation deserves special consideration for their willingness to let us use their land holdings as an experimental site. Site consolidation made the logistics much more manageable than they would have been with multiple sites. Jim Brown, Director of Environmental· Control, was instrumental in obtaining permission within the company and Terry Zich, Hydrologist, served as a cooperative and helpful liaison;
Keith Whittemore of the Amoco Oil Company, and P. D. O\u27Brien of Grant Geophysical Inc., and J. R. Freeman travelled to Grand Forks in midwinter to discuss the project and to offer assistance. Jim Reil of Vibra-Tech Engineers donated the use of a portable seismograph and analyzed the data collected.
My wife and daughters have been especially tolerant of my absences during the fieldwork and preparation of this thesis. Without their cooperation, this endeavor would not have been possible. address coal fracture permeability. Consequently, values for transmissivity, storativity, and specific yield were unobtainable.
During the pumping tests, no significant long term chemical or mineralogical equilibrium changes were observed which could be attributed to the blasting. Water quality changes resulted from pumping during the early time segments of the pump tests. Immediately following a shot 100 feet from a pumping well finished in coal, a short term increase in most chemical parameters was noted. Shots farther away had no apparent effect on chemical quality. Well owners and explorers are advised to collect water quality and pumping drawdown data before any exploration is conducted. The relative productivity of any well can be determined by pumping the well and noting the drawdown with time. If done prior to exploration, these measures provide an excellent basis for evaluation of the effects of blasting
Navigating cancer using online communities: a grounded theory of survivor and family experiences
Purpose: People affected by cancer often have unmet emotional and social support needs. Online cancer communities are a convenient channel for connecting cancer survivors, allowing them to support one another. However, it is unclear whether online community use makes a meaningful contribution to cancer survivorship, as little previous research has examined the experience of using contemporary cancer communities. We aimed to explore the experiences of visitors to online cancer communities.
Methods: Twenty-three in-depth interviews were conducted with online cancer community visitors, including cancer survivors (n = 18), family members (n = 2), and individuals who were both a survivor and family member (n = 3). Interviews were analysed using a grounded theory approach.
Results: A theory developed explaining how individuals ‘navigated’ the experience of cancer using online cancer communities. Online advice and information led participants on a ‘journey to become informed’. Online friendships normalised survivorship and cast participants on a ‘journey to recreate identity’. Participants navigated a ‘journey through different worlds’ as they discovered relevant and hidden communities.
Conclusions: This theory highlights virtual paths people affected by cancer can take to self-manage their experience of the disease. Online community experiences can be improved by promoting online evaluation skills and signposting visitors to bereavement support.
Implications for cancer survivors: Cancer survivors can benefit through both lurking and posting in online communities. However, individuals risk becoming distressed when they befriend individuals who may soon die. Additionally, people affected by rarer cancers can struggle to find shared experiences online and may need to look elsewhere for support
Presupposition projection as proof construction
Even though Van der Sandt's presuppositions as anaphora approach is empirically successful, it fails to give a formal account of the interaction between world-knowledge and presuppositions. In this paper, an algorithm is sketched which is based on the idea of presuppositions as anaphora. It improves on this approach by employing a deductive system, Constructive Type Theory (CTT), to get a formal handle on the way world-knowledge influences presupposition projection. In CTT, proofs for expressions are explicitly represented as objects. These objects can be seen as a generalization of DRT's discourse markers. They are useful in dealing with presuppositional phenomena which require world-knowledge, such as Clark's bridging examples and Beaver's conditional presuppositions
Low latency via redundancy
Low latency is critical for interactive networked applications. But while we
know how to scale systems to increase capacity, reducing latency --- especially
the tail of the latency distribution --- can be much more difficult. In this
paper, we argue that the use of redundancy is an effective way to convert extra
capacity into reduced latency. By initiating redundant operations across
diverse resources and using the first result which completes, redundancy
improves a system's latency even under exceptional conditions. We study the
tradeoff with added system utilization, characterizing the situations in which
replicating all tasks reduces mean latency. We then demonstrate empirically
that replicating all operations can result in significant mean and tail latency
reduction in real-world systems including DNS queries, database servers, and
packet forwarding within networks
Assessing the clear bag initiative as a waste management strategy in the HRM
1 online resource (58 p.) : color illustrationsIncludes abstract and appendices.Includes bibliographical references (p. 52-58).This thesis outlines how social psychology can act as a tool for understanding environmental attitudes and behaviours. When an onset of changes were approved to By-Law-600 on February 3, 2014, curbside collection regulations would include a clear bag program(CBP) as of August 1,2015. At the time of the announcements, local news reports alluded to some residential pushback. To assess whether the program has been an effective waste management strategy as a structural fix, this research collected online and door-to-door surveys, as well as conducted an interview with HRM Solid Waste Manager Matthew Keliher. The results reveal that by and large, residents have adjusted to the changes a year and a half after implementation. Suggesting the structural and educational approach in combination has proved to be an effective waste management strategy in the HRM
From Petri Dish to Main Dish: The Legal Pathway for Cell-Based Meat
Meat grown outside an animal is no longer simply science fiction, and the market is poised for introduction of a variety of so-called cell-based meat products. Commercializing these products will require a clear regulatory path forward. In this Article, we explore that legal pathway. We introduce the concepts of cellular agriculture and cell-based meat, including the science, the state and history of the industry, and the general regulatory background, in which the USDA and FDA are the major players. Further, we explore in particular regulatory aspects of food safety and labeling in the context of cell-based meat. Overall, we contend that there is a viable pathway forward for cultivated meat companies under the current regulatory scheme. But a nontrivial degree of uncertainty remains, and regulators would do well to be proactive in issuing guidance in this space. Moreover, cell-based meat remains vulnerable to legal challenges
An analysis of fast photochemistry over high northern latitudes during spring and summer using in-situ observations from ARCTAS and TOPSE
Observations of chemical constituents and meteorological quantities obtained during the two Arctic phases of the airborne campaign ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) are analyzed using an observationally constrained steady state box model. Measurements of OH and HO_2 from the Penn State ATHOS instrument are compared to model predictions. Forty percent of OH measurements below 2 km are at the limit of detection during the spring phase (ARCTAS-A). While the median observed-to-calculated ratio is near one, both the scatter of observations and the model uncertainty for OH are at the magnitude of ambient values. During the summer phase (ARCTAS-B), model predictions of OH are biased low relative to observations and demonstrate a high sensitivity to the level of uncertainty in NO observations. Predictions of HO_2 using observed CH_2O and H_2O_2 as model constraints are up to a factor of two larger than observed. A temperature-dependent terminal loss rate of HO_2 to aerosol recently proposed in the literature is shown to be insufficient to reconcile these differences. A comparison of ARCTAS-A to the high latitude springtime portion of the 2000 TOPSE campaign (Tropospheric Ozone Production about the Spring Equinox) shows similar meteorological and chemical environments with the exception of peroxides; observations of H_2O_2 during ARCTAS-A were 2.5 to 3 times larger than those during TOPSE. The cause of this difference in peroxides remains unresolved and has important implications for the Arctic HO_x budget. Unconstrained model predictions for both phases indicate photochemistry alone is unable to simultaneously sustain observed levels of CH_2O and H_2O_2; however when the model is constrained with observed CH_2O, H_2O_2 predictions from a range of rainout parameterizations bracket its observations. A mechanism suitable to explain observed concentrations of CH_2O is uncertain. Free tropospheric observations of acetaldehyde (CH_3CHO) are 2–3 times larger than its predictions, though constraint of the model to those observations is sufficient to account for less than half of the deficit in predicted CH_2O. The box model calculates gross O_3 formation during spring to maximize from 1–4 km at 0.8 ppbv d^(−1), in agreement with estimates from TOPSE, and a gross production of 2–4 ppbv d^(−1) in the boundary layer and upper troposphere during summer. Use of the lower observed levels of HO_2 in place of model predictions decreases the gross production by 25–50%. Net O_3 production is near zero throughout the ARCTAS-A troposphere, and is 1–2 ppbv in the boundary layer and upper altitudes during ARCTAS-B
Thermo-Regulated Device for Extremities Affected by Raynaud’s Disease
Raynaud’s condition is a disease in which blood vessels in the extremities constrict in response to emotional stimuli and cold environments. This results in extreme discoloration and pain in the regions affected (Figure 1), and can cause permanent tissue damage. Although there is no current cure for this disease, there are several methods of pain mitigation including the use of drugs, gloves, avoiding exposure to cold weather, and using heating devices. However, these solutions are only temporary. Most gloves do not provide adequate insulation or have a short battery life.
This project is aimed at mediating the negative physiological effects of Raynaud’s disease by developing a thermo-regulated device to regulate the temperature of the extremities. The final prototype utilizes a micro-controller that activates a steel-fiber heating element placed inside of a glove. The closedloop control reacts to a thermocouple signal that measures the user’s hand temperature at several strategic locations. This ensures that the heating element is activated when the hand approaches dangerously low temperature and is deactivated when the temperature of the hand returns to a safe temperature. This automated process eliminates the need for the wearer to manually control the heat setting, while maximizing battery life. Additionally, undesired side effects of overheating such as sweating are avoided.
A device of this nature would revolutionize the world of a person suffering from Raynaud’s disease. Other applications of the gloves include first responders operating in extreme weather. Future studies include optimization of the materials to maximize dexterity without sacrificing insulation.https://scholarscompass.vcu.edu/capstone/1133/thumbnail.jp
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