Design and assembly of a catalyst bed gas generator for the catalytic decomposition of high concentration hydrogen peroxide propellants and the catalytic combustion of hydrocarbon/air mixtures

A method for designing and assembling a high performance catalyst bed gas generator for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in target, space, and on-orbit propulsion systems and low-emission terrestrial power and gas generation. The gas generator utilizes a sectioned catalyst bed system, and incorporates a robust, high temperature mixed metal oxide catalyst. The gas generator requires no special preheat apparatus or special sequencing to meet start-up requirements, enabling a fast overall response time. The high performance catalyst bed gas generator system has consistently demonstrated high decomposition efficiency, extremely low decomposition roughness, and long operating life on multiple test articles

Damage evolution in SiC/SiC unidirectional composites by X‐ray tomography

Melt infiltrated SiC/SiC ceramic matrix composite unidirectional (UD) composite specimens were imaged under load using X‐ray microtomography techniques in order to visualize the evolution of damage accumulation and to quantify damage mechanisms within the composite such as matrix cracking and fiber breaking. The data obtained from these in situ tensile tests were used in comparison with current models and literature results. Three‐dimensional (3D) tomography images were used to measure the location and spacing of matrix cracking that occurred at increasing stress increments during testing within two UD composite specimens. The number of broken fibers and the location of each fiber break gap that occurred within the volume of both specimens were also quantified. The 3D locations of fiber breaks were correlated with the location of each matrix crack within the volume of the specimen and it was found that at the stress scanned directly before failure, most of the fiber breaks occur within 100 microns of a matrix crack.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154464/1/jace17017_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154464/2/jace17017.pd

Application of a mixed metal oxide catalyst to a metallic substrate

A method for applying a mixed metal oxide catalyst to a metallic substrate for the creation of a robust, high temperature catalyst system for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in propulsion systems. The method begins by forming a prepared substrate material consisting of a metallic inner substrate and a bound layer of a noble metal intermediate. Alternatively, a bound ceramic coating, or frit, may be introduced between the metallic inner substrate and noble metal intermediate when the metallic substrate is oxidation resistant. A high-activity catalyst slurry is applied to the surface of the prepared substrate and dried to remove the organic solvent. The catalyst layer is then heat treated to bind the catalyst layer to the surface. The bound catalyst layer is then activated using an activation treatment and calcinations to form the high-activity catalyst system

High-temperature catalyst for catalytic combustion and decomposition

A robust, high temperature mixed metal oxide catalyst for propellant composition, including high concentration hydrogen peroxide, and catalytic combustion, including methane air mixtures. The uses include target, space, and on-orbit propulsion systems and low-emission terrestrial power and gas generation. The catalyst system requires no special preheat apparatus or special sequencing to meet start-up requirements, enabling a fast overall response time. Start-up transients of less than 1 second have been demonstrated with catalyst bed and propellant temperatures as low as 50 degrees Fahrenheit. The catalyst system has consistently demonstrated high decomposition effeciency, extremely low decomposition roughness, and long operating life on multiple test particles

Crack opening behavior in ceramic matrix composites

The evolution of matrix cracks in a melt‐infiltrated SiC/SiC ceramic matrix composite (CMC) under uniaxial tension was examined using scanning electron microscopy (SEM) combined with digital image correlation (DIC) and manual crack opening displacement (COD) measurements. CMC modeling and life prediction strongly depend a thorough understanding of when matrix cracks occur, the extent of cracking for given conditions (time‐temperature‐environment‐stress), and the interactions of matrix cracks with fibers and interfaces. In this work, strain relaxation due to matrix cracking, the relationship between CODs and applied stress, and damage evolution at stresses below the proportional limit were assessed. Direct experimental observation of strain relaxation adjacent to regions of matrix cracking is presented and discussed. Additionally, crack openings were found to increase linearly with increasing applied stress, and no crack was found to pass fully through the gage cross‐section. This calls into question the modeling assumption of through‐cracks for all loading conditions and fiber architectures, which can obscure oxidation mechanisms that are active in realistic cracking conditions. Finally, the combination of SEM with DIC is demonstrated throughout to be a powerful means for damage identification and quantification in CMCs at stresses well below the proportional limit.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138389/1/jace14976_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138389/2/jace14976.pd

Crack Opening Displacement Behavior in Ceramic Matrix Composites

Ceramic Matrix Composites (CMC) modeling and life prediction strongly depend on oxidation, and therefore require a thorough understanding of when matrix cracks occur, the extent of cracking for given conditions (time-temperature-environment-stress), and the interactions of matrix cracks with fibers and interfaces. In this work, the evolution of matrix cracks in a melt-infiltrated Silicon Carbide/Silicon Carbide (SiC/SiC) CMC under uniaxial tension was examined using scanning electron microscopy (SEM) combined with digital image correlation (DIC) and manual crack opening displacement (COD) measurements. Strain relaxation due to matrix cracking, the relationship between COD's and applied stress, and damage evolution at stresses below the proportional limit were assessed. Direct experimental observation of strain relaxation adjacent to regions of matrix cracking is presented and discussed. Additionally, crack openings were found to increase linearly with increasing applied stress, and no crack was found to pass fully through the gage cross-section. This observation is discussed in the context of the assumption of through-cracks for all loading conditions and fiber architectures in oxidation modeling. Finally, the combination of SEM with DIC is demonstrated throughout to be a powerful means for damage identification and quantification in CMC's at stresses well below the proportional limit

Matrix Cracking of Ceramic-Matrix Composites

In this chapter, the matrix cracking of fiber-reinforced ceramic-matrix composites (CMCs) is investigated using the energy balance approach. The relationship between the matrix cracking stress, fiber and interface oxidation, and fiber failure is established. The effects of the fiber volume, interface shear stress and interface debonding energy, fiber failure, and oxidation temperature on the time-dependent matrix cracking stress are analyzed. The experimental matrix cracking stress of different fiber-reinforced CMCs is predicted using the present models

Regulating Tiger Kings

Joe Exotic, the star of the widely watched documentary, “Tiger King,” reportedly owned more than 200 tigers on his compound in Oklahoma prior to being sentenced to jail for various criminal violations. The U.S. Fish and Wildlife Service states that “the number of captive tigers in the United States alone likely exceeds the numbers found in the wild.” Private possession of big cats poses risks to humans of brutal, deadly animal attacks. It also poses risks to the animals themselves who suffer from mistreatment and neglect. Proposed bipartisan federal legislation would prohibit individuals who are not licensed by the U.S. Department of Agriculture (USDA) from possessing big cats—including lions, tigers, leopards, cheetahs, jaguars, and cougars. It also would prohibit public contact with big cats. The legislation would allow current owners of big cats to keep them but would require registration of each animal so that law enforcement officers are able to respond quickly to an accident. Current owners would not be allowed to breed their big cats and would be prevented from allowing public contact with their cats. The proposed legislation, known as the Big Cat Public Safety Act and sponsored by U.S. Representative Brian Fitzpatrick (R-Pa.) and U.S. Representative Mike Quigley (D-Ill.), has garnered support from over 200 representatives across party lines. Quigley argues that the legislation is needed to “address a serious issue that causes immeasurable animal suffering and introduces inexcusable threats to human safety.” Although regulation of big cats currently occurs at international, federal, and state levels, critics argue that existing laws are not stringent enough and do not accomplish the goals of keeping humans and big cats safe. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is an international treaty aimed at preventing international trade from harming endangered species. CITES provides a framework for nations to follow by stating that certain species of animals should not be traded unless certain circumstances apply. But CITES then leaves it to individual nations to create their own enforcement measures. To comply with CITES, as well as other treaties, the United States enacted the Endangered Species Act (ESA). The ESA prohibits people from “taking” endangered or threatened species, including harassing, harming, capturing, or trapping such species. The U.S. Fish and Wildlife Service classifies all tigers as endangered, one subspecies of lion as endangered, and another subspecies of lion as threatened. In 2016, the U.S. Fish and Wildlife closed a loophole in the ESA that exempted certain “generic tigers” from otherwise prohibited activities such as “interstate commerce and export.” The ESA does not, however, restrict movement or sale of endangered species within states. By banning breeding and non-licensed possession of big cats, the Big Cat Public Safety Act could help prevent sales of big cats. Another federal law, the Animal Welfare Act, dictates minimum standards for exotic animal exhibitors and dealers. Using its authority under the Animal Welfare Act, USDA issued rules requiring exhibitors and dealers to obtain a license and to follow certain “humane handling, shelter, space requirements, feeding, watering, sanitation, ventilation, veterinary care, and transport” standards. Critics argue that the Trump Administration is failing to conduct adequate animal welfare inspections and that enforcement cases have declined 92 percent from 2016. Under a law passed in 2003—the Captive Wildlife Safety Act—transporters, exhibitors, and owners of big cats do face the need to comply with some federal regulations. Under this law, no big cats are allowed to be transported across state lines for any reason, including for household moves or veterinary visits, unless the mover qualifies for an exemption. Exempt entities include individuals registered under the Animal Welfare Act, “state colleges and universities, state agencies, … state-licensed veterinarians, and wildlife sanctuaries.” The Captive Wildlife Safety Act defines sanctuaries as non-profit organizations that do not sell big cats, their parts, or products made from them, do not breed big cats, and do not allow members of the public to have direct contact with big cats. Sanctuaries must keep records of transactions involving big cats as well as allow inspections of the facilities, records, and animals. But neither the Captive Wildlife Safety Act nor the Animal Welfare Act prohibit private possession of big cats—nor do they require licensing for private owners. The Big Cat Public Safety Act would address both of those regulatory gaps. Without such a federal law, regulation falls to the states. According to a 2019 report, four states do not regulate possession of dangerous wild animals at all, and six states do not ban possession of big cats as pets. This is why proponents of the proposed federal Big Cat Public Safety Act say it is needed. They argue that “captive big cats … killed 20 adults and mauled scores of others” and that private ownership of big cats causes physical and psychological harm to the animals. These proponents explain that “the current regulatory patchwork is failing to protect public safety and animal welfare,” necessitating a federal ban on big cat possession. Opponents of the proposed legislation argue that it would curtail “existing legal business activity.” U.S. Representative Rob Bishop (R-Utah) reportedly argued that “the proposal pits small, family-owned animal parks against big zoos, which would be able to keep their cats.

Parque Regional de la Cuenca Alta del Manzanares

La cuenca alta del río Manzanares, que goza del título de Parque Regional, es una joya de la Sierra de Guadarrama, al noroeste de Madrid. La belleza singular de este paraje, sus aguas cristalinas y su proximidad a la capital hacen del parque un espacio muy concurrido. La fuerte presión humana a que está sujeto el parque se concentra principalmente en las márgenes del río Manzanares, mientras que la topografía agreste del enclave dificulta el acceso a las zonas alejadas del río, protegiéndolas así de la masificación que experimenta el río durante los fines de semana del verano

The Power of the Paris Agreement

The leaders of 189 nations have ratified the Paris Agreement, pledging to address climate change through emissions reduction and adaptation measures. But the largest emitter of greenhouse gases per capita, the United States, has announced its intention to withdraw from this agreement. Given that nations can withdraw from the Paris Agreement and that any national pledges made under it are essentially non-binding, is this global climate accord accomplishing anything meaningful? The authors of a recent law review article argue that the Paris Agreement has still greater influence beyond individual nations’ pledges. In their article, law professor David Hunter of American University and two of his law students, Wenhui Ji and Jenna Ruddock, claim that the Paris Agreement guides courts in litigation aimed at improving governments’ climate change responses. It also plays a role in litigation by requiring fossil fuel companies to disclose the financial risks that climate change poses for their products. Although the Paris Agreement itself is binding, nations’ individual commitments—that is, their nationally determined contributions (NDCs)—are non-binding under international law. Each nation submits its own NDC, explaining what measures it will take to address climate change, such as emissions reductions or other mitigation efforts. But in domestic law, courts sometimes use NDCs as a benchmark to determine whether governments are taking adequate steps toward their Paris Agreement pledges. Hunter and his coauthors explain that courts can hold their governments accountable for failing to meet their commitments. For example, in New Zealand, a court held that the national government needs to reconsider its NDC based on new climate science. And in South Africa, a court held that the government’s approval of a coal-fired power plant was invalid because the government failed to conduct a “climate change impact assessment.” Hunter and his coauthors explain that the court used South Africa’s NDC as a “’generally agreed’ benchmark for evaluating government decisions relating to climate change” and required the government to consider whether building a new coal-fired power plant would be consistent with its NDC. Another way that courts are using the Paris Agreement, Hunter and his coauthors explain, is to enforce international human rights. A Dutch court, for example, used a two-degree temperature standard in a human rights-based lawsuit. This was because the Paris Agreement pronounces a goal of keeping the rise in the global temperature to not more than two degrees Celsius above pre-industrial temperatures. In Urgenda v. Netherlands, an environmental group sued the Dutch government for weakening the nation’s emissions reduction plan. The group argued that the additional emissions caused by the new plan would raise global temperatures and harm human life. It also claimed that these harms would violate the government’s responsibility to protect the “right to life” required by the European Convention on the Protection of Human Rights and Fundamental Freedoms. The court agreed, using the Paris Agreement as evidence that temperature increases above two degrees would cause severe impacts and harm human life in violation of the government’s duty of care to its citizens. In addition to using NDCs as a tool to hold individual governments accountable, these commitments signal economic risks of fossil fuel use that are starting to shift financial incentives away from investing in fossil fuels, Hunter and his coauthors suggest. The Paris Agreement reveals a “global consensus” about the harms of carbon emissions, sending a “clear signal” that there will be strict regulation of carbon emissions in the future, Hunter and his coauthors argue. They also explain that the Paris Agreement demonstrates an intention to move away from fossil fuels toward other energy sources. These signals will affect future litigation about fossil fuel finances significantly, Hunter and his coauthors predict. As demand for fossil fuels declines, the value of fossil fuel-based assets—such as oil, gas, and coal—will also decline. Hunter and his coauthors argue that as fossil fuel regulations increase—such as through the adoption of carbon taxes or emissions reductions—the costs of using fossil fuels will also increase. Hunter and his coauthors say that fossil fuel companies have to explain the risks of increased prices and decreased demand in financial disclosure statements. They argue that companies that fail to disclose these risks could be liable for fraud and misleading shareholders. The Attorney General of New York, for example, has already attempted to pursue a lawsuit of this type against a fossil fuel company, alleging that the company misled shareholders about the implications of climate change. Hunter and his coauthors argue that the Paris Agreement puts carbon-intensive industries “on notice” and opens the door for more lawsuits to force fossil fuel companies to disclose the financial realities of the industry. In these ways, the Paris Agreement demonstrates a globally accepted understanding of the causes and effects of climate change and offers potential solutions to the problem, Hunter and his coauthors argue. They conclude that the Paris Agreement “provides a valid framework within which a court can evaluate climate mitigation efforts, financial disclosures, and investor expectations.