Space station integrated propulsion and fluid systems study

The program study was performed in two tasks: Task 1 addressed propulsion systems and Task 2 addressed all fluid systems associated with the Space Station elements, which also included propulsion and pressurant systems. Program results indicated a substantial reduction in life cycle costs through integrating the oxygen/hydrogen propulsion system with the environmental control and life support system, and through supplying nitrogen in a cryogenic gaseous supercritical or subcritical liquid state. A water sensitivity analysis showed that increasing the food water content would substantially increase the amount of water available for propulsion use and in all cases, the implementation of the BOSCH CO2 reduction process would reduce overall life cycle costs to the station and minimize risk. An investigation of fluid systems and associated requirements revealed a delicate balance between the individual propulsion and fluid systems across work packages and a strong interdependence between all other fluid systems

Culture Wars on Campus: Academic Freedom, the First Amendment, and Partisan Outrage in Polarized Times

After a California community college professor called the election of President Donald Trump an “act of terrorism” in her classroom the week after the vote, a student-recorded viral video sparked a national conservative media firestorm. Critics said the professor should be fired for outrageous liberal bias, while supporters defended her comments as being protected by academic freedom and the First Amendment. The student, meanwhile, was suspended for his unauthorized recording while defenders decried his punishment as evidence of anti-conservative discrimination and harassment. By examining tensions between faculty and student speech rights, the use of technologies to take ideological disagreements viral through partisan media, and the role of colleges and universities in culture wars, this paper finds deep divisions in views of rights and responsibilities of faculty, students, and institutions in campus free-expression controversies

Relative Comparison Kernel Learning with Auxiliary Kernels

In this work we consider the problem of learning a positive semidefinite kernel matrix from relative comparisons of the form: "object A is more similar to object B than it is to C", where comparisons are given by humans. Existing solutions to this problem assume many comparisons are provided to learn a high quality kernel. However, this can be considered unrealistic for many real-world tasks since relative assessments require human input, which is often costly or difficult to obtain. Because of this, only a limited number of these comparisons may be provided. In this work, we explore methods for aiding the process of learning a kernel with the help of auxiliary kernels built from more easily extractable information regarding the relationships among objects. We propose a new kernel learning approach in which the target kernel is defined as a conic combination of auxiliary kernels and a kernel whose elements are learned directly. We formulate a convex optimization to solve for this target kernel that adds only minor overhead to methods that use no auxiliary information. Empirical results show that in the presence of few training relative comparisons, our method can learn kernels that generalize to more out-of-sample comparisons than methods that do not utilize auxiliary information, as well as similar methods that learn metrics over objects

Beam tests of the 12 MHz RFQ RIB injector for ATLAS

Beam tests of the ANL 12 MHz Radio-Frequency Quadrupole (RFQ), designed for use as the initial element of an injector system for radioactive beams into the existing ATLAS accelerators, are in progress. Recent high-voltage tests of the RFQ without beam achieved the design intervane voltage of 100 kV cw, enabling beam tests with A /q as large as 132 using beams from the ANL Physics Division 4 MV Dynamitron accelerator facility. Although the RFQ was designed for bunched beams, initial tests have been performed with unbunched beams. Experiments with stable, unbunched beams of singly-charged /sup 132/Xe and /sup 84/Kr measured the output beam energy distribution as a function of the RFQ operating voltage. The observed energies are in excellent agreement with numerical beam simulations. (5 refs)

Direct measurement of the transmission matrix of a mesoscopic conductor

We have developed an experimental approach which permits evaluation of the entire transmission matrix of a mesoscopic conductor. Results are presented from two new investigations enabled by this technique: (a) We study ballistic multiprobe conductors in the limit of weak probe coupling, and (b) we image modal features in the distribution function of electrons emerging from a quantum point contact

The wavelength dependence of Martian atmospheric dust radiative properties

One of the key radiative agents in the atmosphere of Mars is the suspended dust particles. A new analysis of two data sets of the Martian atmosphere is being carried out in order to better evaluate the radiative properties of the atmospheric dust particles. The properties of interest are the size distribution, optical constants, and other radiative properties, such as the single-scattering albedo and phase function. Of prime importance is the wavelength dependence of these radiative properties throughout the visible and near-infrared wavelengths. Understanding the wavelength dependence of absorption and scattering characteristics will provide a good definition of the influence that the atmospheric dust has on heating of the atmosphere

Measuring Relations Between Concepts In Conceptual Spaces

The highly influential framework of conceptual spaces provides a geometric way of representing knowledge. Instances are represented by points in a high-dimensional space and concepts are represented by regions in this space. Our recent mathematical formalization of this framework is capable of representing correlations between different domains in a geometric way. In this paper, we extend our formalization by providing quantitative mathematical definitions for the notions of concept size, subsethood, implication, similarity, and betweenness. This considerably increases the representational power of our formalization by introducing measurable ways of describing relations between concepts.Comment: Accepted at SGAI 2017 (http://www.bcs-sgai.org/ai2017/). The final publication is available at Springer via https://doi.org/10.1007/978-3-319-71078-5_7. arXiv admin note: substantial text overlap with arXiv:1707.05165, arXiv:1706.0636

Asymmetric Induction in Intramolecular [2 + 2]-Photocycloadditions of 1,3-Disubstituted Allenes with Enones and Enoates

Irradiation of optically active allenes (89-92% ee) appended to enones and enoates affords alkylidenecyclobutane photoadducts with high levels of asymmetric induction (83-100%) derived exclusively from the allene fragment. The substrates studied include allenes tethered to enones such as 1,3-cyclohexanedionea nd 1,3-cyclopentanedione, as well as allenes tethered to functionalized coumarins. The enantiomer ratios of the photoadducts were quantified by derivatization of the products as the corresponding Mosher MTPA esters and analysis by ^1H NMR spectroscopy. The exo-methylenecyclobutanes obtained upon irradiation of allene-mumarins are isolated as single olefin diastereomers. Irradiation of a coumarin tethered at C(5) with an optically active allene affords an alkynyl-substituted oxepane with complete asymmetric induction

Symmetric and asymmetric action integration during cooperative object manipulation in virtual environments

Cooperation between multiple users in a virtual environment (VE) can take place at one of three levels. These are defined as where users can perceive each other (Level 1), individually change the scene (Level 2), or simultaneously act on and manipulate the same object (Level 3). Despite representing the highest level of cooperation, multi-user object manipulation has rarely been studied. This paper describes a behavioral experiment in which the piano movers' problem (maneuvering a large object through a restricted space) was used to investigate object manipulation by pairs of participants in a VE. Participants' interactions with the object were integrated together either symmetrically or asymmetrically. The former only allowed the common component of participants' actions to take place, but the latter used the mean. Symmetric action integration was superior for sections of the task when both participants had to perform similar actions, but if participants had to move in different ways (e.g., one maneuvering themselves through a narrow opening while the other traveled down a wide corridor) then asymmetric integration was superior. With both forms of integration, the extent to which participants coordinated their actions was poor and this led to a substantial cooperation overhead (the reduction in performance caused by having to cooperate with another person)