Preliminary assessment of power-generating tethers in space and of propulsion for their orbit maintenance

The concept of generating power in space by means of a conducting tether deployed from a spacecraft was studied. Using hydrogen and oxygen as the rocket propellant to overcome the drag of such a power-generating tether would yield more benefit than if used in a fuel cell. The mass consumption would be 25 percent less than the reactant consumption of fuel cells. Residual hydrogen and oxygen in the external tank and in the orbiter could be used very effectively for this purpose. Many other materials (such as waste from life support) could be used as the propellant. Electrical propulsion using tether generated power can compensate for the drag of a power-generating tether, half the power going to the useful load and the rest for electric propulsion. In addition, the spacecraft's orbital energy is a large energy reservoir that permits load leveling and a ratio of peak to average power equal to 2. Critical technologies to be explored before a power-generating tether can be used in space are delineated

Driven Intrinsic Localized Modes in a Coupled Pendulum Array

Intrinsic localized modes (ILMs), also called discrete breathers, are directly generated via modulational instability in an array of coupled pendulums. These ILMs can be stabilized over a range of driver frequencies and amplitudes. They are characterized by a pi-phase difference between their center and wings. At higher driver frequencies, these ILMs are observed to disintegrate via a pulsating instability, and the mechanism of this breather instability is investigated.Comment: 5 pages, 6 figure

Undergraduate Adult Education in the Contemporary Neoliberal University

In contemporary times, undergraduate adult education programs have to respond to changing student profiles and needs, institutional requirements, marketplace and workplace demands, and emerging technologies. Students in these programs tend to be non-traditional learners who are usually older and employed. They come with an array of prior learning experiences in life, work, and community contexts. These motivated learners have diverse reasons for wanting to engage in academic studies in adult education: They require knowledge of adult education to become trainers in business and industry; they have been educators, but they need to know what’s new to enhance and update their everyday pedagogical practices; they seek a university credential to ensure a new future; they need new learning for job transitions; they need to learn new modes of assessment; they want to work with industry partners to write curricula. This list of reasons is far from exhaustive. Considering the kinds of non-traditional students seeking a Bachelor of Education in Adult Education today, admission requirements need to be more in tune with what they bring to the learning table. For example, prior learning assessment that recognizes significant experiential learning could be a stronger criterion in the admissions process. In this perspective piece, we examine the current learning milieu in the neoliberal university and some matters affecting student participation in undergraduate adult education.À l’époque contemporaine, les programmes de premier cycle d’éducation des adultes doivent s’adapter à l’évolution des profils et des besoins des étudiants, des exigences institutionnelles, des demandes du marché du travail et des milieux de travail, et des nouvelles technologies. Les étudiants inscrits à ces programmes tendent à être des apprenants non-traditionnels qui sont souvent plus âgés et salariés. Ils arrivent avec toute une gamme d’expériences d’apprentissage dans la vie, au travail et dans la communauté. Les raisons qui poussent ces apprenants motivés à entreprendre des études académiques sont diverses : il leur faut les connaissances fournies par les programme d’éducation des adultes pour devenir formateurs dans le monde des affaires ou en industrie; ils ont été enseignants mais doivent se mettre à jour de sorte à améliorer et moderniser leur pratiques pédagogiques; ils désirent une accréditation universitaire pour s’assurer un nouvel avenir; ils ont besoin de nouvelles connaissances pour changer d’emploi; ils doivent apprendre de nouvelles formes d’évaluation; ils veulent travailler avec des partenaires du secteur pour créer du matériel pédagogique. Cette liste est loin d’être exhaustive. Compte tenu du genre d’étudiants non-traditionnels qui s’inscrivent au Baccalauréat en Éducation en éducation des adultes, les exigences d’admission doivent être davantage en phase avec les compétences et les expériences avec lesquelles ils arrivent à l’université. Par exemple, une évaluation des connaissances acquises qui tiendrait compte de l’apprentissage par l’expérience pourrait constituer un critère de choix plus important pendant le processus d’admission. Dans cet article d’opinion, nous nous penchons sur le milieu actuel de l’apprentissage dans le monde universitaire néolibéral et sur quelques enjeux touchant la participation des étudiants dans les programmes de premier cycle en éducation des adultes.Mots clés : programmes de premier cycle en éducation des adulte

Discrete breathers in a nonlinear electric line: Modeling, Computation and Experiment

We study experimentally and numerically the existence and stability properties of discrete breathers in a periodic nonlinear electric line. The electric line is composed of single cell nodes, containing a varactor diode and an inductor, coupled together in a periodic ring configuration through inductors and driven uniformly by a harmonic external voltage source. A simple model for each cell is proposed by using a nonlinear form for the varactor characteristics through the current and capacitance dependence on the voltage. For an electrical line composed of 32 elements, we find the regions, in driver voltage and frequency, where $n$-peaked breather solutions exist and characterize their stability. The results are compared to experimental measurements with good quantitative agreement. We also examine the spontaneous formation of $n$-peaked breathers through modulational instability of the homogeneous steady state. The competition between different discrete breathers seeded by the modulational instability eventually leads to stationary $n$-peaked solutions whose precise locations is seen to sensitively depend on the initial conditions

Polarization dependent photoionization cross-sections and radiative lifetimes of atomic states in Ba

The photoionization cross-sections of two even-parity excited states, $5d6d ^3D_1$ and $6s7d ^3D_{2}$, of atomic Ba at the ionization-laser wavelength of 556.6 nm were measured. We found that the total cross-section depends on the relative polarization of the atoms and the ionization-laser light. With density-matrix algebra, we show that, in general, there are at most three parameters in the photoionization cross-section. Some of these parameters are determined in this work. We also present the measurement of the radiative lifetime of five even-parity excited states of barium.Comment: 11 pages, 7 figure

Unusually large polarizabilities and "new" atomic states in Ba

Electric polarizabilities of four low-J even-parity states and three low-J odd-parity states of atomic barium in the range $35,600$ to $36,000\ $cm$^{-1}$are investigated. The states of interest are excited (in an atomic beam) via an intermediate odd-parity state with a sequence of two laser pulses. The odd-parity states can be excited due to the Stark-induced mixing with even-parity states. The polarizabilities are measured via direct spectroscopy on the second-stage transition. Several states have tensor and scalar polarizabilities that exceed the values that might be expected from the known energy levels of barium by more than two orders of magnitude. Two of the Stark-induced transitions cannot be identified from the known energy spectrum of barium. The observations suggest the existence of as yet unidentified odd-parity energy states, whose energies and angular momenta are determined in the present experiment. A tentative identification of these states as [Xe]$6s8p ^3P_{0,2}$ is suggested.Comment: 29 pages, 12 figure

Hyperfine-interaction- and magnetic-field-induced Bose-Einstein-statistics suppressed two-photon transitions

Two-photon transitions between atomic states of total electronic angular momentum $J_a=0$ and $J_b=1$ are forbidden when the photons are of the same energy. This selection rule is analogous to the Landau-Yang theorem in particle physics that forbids decays of vector particle into two photons. It arises because it is impossible to construct a total angular momentum $J_{2\gamma}=1$ quantum-mechanical state of two photons that is permutation symmetric, as required by Bose-Einstein statistics. In atoms with non-zero nuclear spin, the selection rule can be violated due to hyperfine interactions. Two distinct mechanisms responsible for the hyperfine-induced two-photon transitions are identified, and the hyperfine structure of the induced transitions is evaluated. The selection rule is also relaxed, even for zero-nuclear-spin atoms, by application of an external magnetic field. Once again, there are two similar mechanisms at play: Zeeman splitting of the intermediate-state sublevels, and off-diagonal mixing of states with different total electronic angular momentum in the final state. The present theoretical treatment is relevant to the ongoing experimental search for a possible Bose-Einstein-statistics violation using two-photon transitions in barium, where the hyperfine-induced transitions have been recently observed, and the magnetic-field-induced transitions are being considered both as a possible systematic effect, and as a way to calibrate the measurement

Discrete breathers in a forced-damped array of coupled pendula: Modeling, Computation and Experiment

In this work, we present a mechanical example of an experimental realization of a stability reversal between on-site and inter-site centered localized modes. A corresponding realization of a vanishing of the Peierls-Nabarro barrier allows for an experimentally observed enhanced mobility of the localized modes near the reversal point. These features are supported by detailed numerical computations of the stability and mobility of the discrete breathers in this system of forced and damped coupled pendula. Furthermore, additional exotic features of the relevant model, such as dark breathers are briefly discussed

Longmeyer Exposes or Creates Uncertainty about the Duty to Inform Remainder Beneficiaries of a Revocable Trust

This article discusses the surprising Longmeyer decision, handed down by the Supreme Court of Kentucky earlier this year in which a predecessor trustee was held to have a duty to give certain notifications to former remainder beneficiaries of a revocable trust. The authors then examine how Longmeyer might have been decided in other states and under other statutory schemes. The article concludes with observations concerning when certain notices to trust beneficiaries may be conducive to effective trust administration and suggestions to those who administer trusts on how best to comply with beneficiary notice requirements

Waste-Wood-Derived Fillers for Plastics

Filled thermoplastic composites are stiffer, stronger, and more dimensionally stable than their unfilled counterparts. Such thermoplastics are usually provided to the end-user as a precompounded, pelletized feedstock. Typical reinforcing fillers are inorganic materials like talc or fiberglass, but materials derived from waste wood, such as wood flour and recycled paper fiber, are also effective as fillers. The goal of this project was to generate commercial interest in using waste-wood–paper-derived fillers (WPFs) to reinforce thermoplastics. The research strategy was twofold: developmental research and outreach. Specific objectives were (1) to improve wastepaper fiber preparation, feeding, and compounding methods, and optimize composite performance, and (2) to communicate to end-product manufacturers the advantages of WPF thermoplastics. The research was led and supported by the Forest Products Laboratory (FPL), with input from a consortium of 15 fiber suppliers and plastics manufacturers. Additional funding was provided by the Wisconsin Department of Natural Resources. Equipment was leased and installed at FPL. Eight general purpose formulations were developed—they included extrusion and injection molding grades of both polyethylene and polypropylene, reinforced with WPFs. An information packet containing performance data, appropriate processing conditions, sample pellets, sample parts, and a questionnaire was sent to nearly 500 commercial plastics manufacturers in Wisconsin, Illinois, and Michigan. In response to requests for in-house trials, FPL researchers conducted nearly 18 site visits. The researchers ensured proper handling of the material, provided consultation, and gathered information about processing and performance. The trials went very well, and parts were successfully manufactured at all facilities. Products included automobile trim components and housings, vacuum cleaner parts, paint brush handles, bicycle parts, cosmetic cases, and other household items. Great interest has been shown in the use of WPF thermoplastics; one consortium member is establishing a 4 million kg/yr (9 million lb/yr) facility. Total market demand is conservatively expected to exceed 45 million kg/yr (100 million lb/yr)