Literature review and experimental investigation of heat pipes

Tests on heat pipes determine operational limits, external boundary conditions, noncondensable gas effects, startup behavior, and geometric configurations. Experiment consists of design, construction, and testing of an apparatus for measuring wick properties, conventional heat pipes and coplanar heat pipes

Stable retrograde orbits around the triple system 2001 SN263

The NEA 2001 SN263 is the target of the ASTER MISSION - First Brazilian Deep Space Mission. Araujo et al. (2012), characterized the stable regions around the components of the triple system for the planar and prograde cases. Knowing that the retrograde orbits are expected to be more stable, here we present a complementary study. We now considered particles orbiting the components of the system, in the internal and external regions, with relative inclinations between $90^{\circ}< I \leqslant180^{\circ}$, i.e., particles with retrograde orbits. Our goal is to characterize the stable regions of the system for retrograde orbits, and then detach a preferred region to place the space probe. For a space mission, the most interesting regions would be those that are unstable for the prograde cases, but stable for the retrograde cases. Such configuration provide a stable region to place the mission probe with a relative retrograde orbit, and, at the same time, guarantees a region free of debris since they are expected to have prograde orbits. We found that in fact the internal and external stable regions significantly increase when compared to the prograde case. For particles with $e=0$ and $I=180^{\circ}$, we found that nearly the whole region around Alpha and Beta remain stable. We then identified three internal regions and one external region that are very interesting to place the space probe. We present the stable regions found for the retrograde case and a discussion on those preferred regions. We also discuss the effects of resonances of the particles with Beta and Gamma, and the role of the Kozai mechanism in this scenario. These results help us understand and characterize the stability of the triple system 2001 SN263 when retrograde orbits are considered, and provide important parameters to the design of the ASTER mission.Comment: 11 pages, 8 figures. Accepted for publication in MNRAS - 2015 March 1

Dichte- und Viskositätsmessungen an Quecksilber und hochverdünnten Kalium- und Cäsiumamalgamen vom Erstarrungspunkt bis + 30°C

Die Temperaturabhängigkeit der Dichte und der Viskosität des Quecksilbers sowie hochverdünnter Kalium- und Cäsiumamalgame wird von 30° C bis zum Erstarrungspunkt gemessen. Der Volumen-Ausdehnungskoeffizient α ist bei Cs-Amalgamen größer als bei K-Amalgamen und nimmt von αHg beginnend proportional der Alkalimetall-Konzentration zu. Auch die spez. Volumina der Amalgame nehmen von dem des reinen Quecksilbers an proportional der Konzentration zu. Die hieraus berechneten Atomvolumen (VK) und (VCs) der beiden Alkalimetalle im Amalgam sind nur um etwa 10% verschieden und von der Konzentration unabhängig. Sie nehmen linear mit der Temperatur zu; die Volumenkontraktion δ hingegen verringert sich mit zunehmender Temperatur. — Die Temperaturabhängigkeit der Viskosität η läßt sich mit einer Genauigkeit bis zu einigen Zehntel Promille durch η = η0·eq/RT wiedergeben mit η0η0 = const; die Ansätze η0 ∾ T-1/2,η0 ∾ T1/2, η0 ∾ T ergeben größere Abweichungen. Für reines Quecksilber ist die Platzwechselenergie q = 657,9 cal, für K-Amalgam von c′ = 1,91 Atomen K in 1000 Atomen Amalgam ist qK = 714,6 cal und für gleichverdünntes Cs-Amalgam qCS = 690,4. Hieraus und aus dem Dichteverhalten wird gefolgert, daß die K-Atome eine (weniger dicht gepackte) Hg-Hülle von größerem Volumen mit sich führen als die Cs-Atome. Das Volumen φ dieser Hülle läßt sich berechnen unter Verwendung eines Ansatzes von Einstein für die Viskosität einer Lösung von größeren Kugeln in einem Medium kleinerer Kugeln. Aus der Temperaturabhängigkeit von φ erhält man die zur Abtrennung von 1 g-Atom Quecksilber erforderliche Energie ε; εκ = 278,9 cal, εCs= 359,3 cal. εκ ist kleiner als εCs, weil die Hg-Atome um die K-Atome weniger dicht gepackt sind. — Zwischen der Volumenkontraktion δ der Alkaliatome im Amalgam und φ besteht eine lineare Beziehung; δ setzt sich additiv aus einem temperaturunabhängigen und einem temperaturabhängigen Anteil zusammen. Beide Anteile kommen beim Cs-Amalgam stärker zur Geltung als beim K-Amalgam

Measuring Polynomial Invariants of Multi-Party Quantum States

We present networks for directly estimating the polynomial invariants of multi-party quantum states under local transformations. The structure of these networks is closely related to the structure of the invariants themselves and this lends a physical interpretation to these otherwise abstract mathematical quantities. Specifically, our networks estimate the invariants under local unitary (LU) transformations and under stochastic local operations and classical communication (SLOCC). Our networks can estimate the LU invariants for multi-party states, where each party can have a Hilbert space of arbitrary dimension and the SLOCC invariants for multi-qubit states. We analyze the statistical efficiency of our networks compared to methods based on estimating the state coefficients and calculating the invariants.Comment: 8 pages, 4 figures, RevTex4, v2 references update

There is a Bias in Aviation Against Research That is Perceived to be “Easy”

The purpose of conducting research is to make contributions to the body of knowledge. In managing research studies, researchers are often forced to make decisions on a series of tradeoffs due to scarce resources. They may have to select participants from certain accessible populations, limit the time required to conduct the study, or use a minimal number of researchers due to funding constraints. The purpose of this current study was to examine for a possible bias on the perceived value of scientific research based on the location in which the data was collected, the amount of time required to complete the study, and the number of researchers involved in the study. Over a series of four studies, 1796 total participants provided ratings on their perceived scientific value of the accomplished research. The findings indicated that those studies which were conducted in a laboratory, took more time, and used more researchers had more perceived scientific value than the exact same study completed in a classroom, in a shorter amount of time, and with fewer researchers. Additionally, ease/difficulty was shown to be a significant mediator, further providing evidence that the perceived ease or difficulty of the study was influencing the participants’ ratings

2001 SN263-the contribution of their irregular shapes on the neighbourhood dynamics

The first proposed Brazilian mission to deep space, the ASTER mission, has the triple asteroid system (153591) 2001 SN263 as a target. One of the mission's main goals is to analyse the physical and dynamical structures of the system to understand its origin and evolution. This work aims to analyse how the asteroid's irregular shape interferes with the stability around the system. The results show that the irregular shape of the bodies plays an important role in the dynamics nearby the system. For instance, the perturbation due to the (153591) 2001 SN263 Alpha's shape affects the stability in the (153591) 2001 SN263 Gamma's vicinity. Similarly, the (153591) 2001 SN263 Beta's irregularity causes a significant instability in its nearby environment. As expected, the prograde case is the most unstable, while the retrograde scenario presents more stability. Additionally, we investigate how the solar radiation pressure perturbs particles of different sizes orbiting the triple system. We found that particles with a 10-50 cm radius could survive the radiation pressure for the retrograde case. Meanwhile, to resist solar radiation, the particles in prograde orbit must be larger than the particles in retrograde orbits, at least one order of magnitude.This study was financed in part by the Brazilian Federal Agency for Support and Evaluation of Graduate Education (CAPES), in the scope of the Program CAPES-PrInt, process number 88887.310463/2018-00, International Cooperation Project number 3266, Fundaçao de Amparo à Pesquisa do Estado de Sao Paulo (FAPESP) - Proc. 2016/24561-0 and Proc. 2019/23963-5, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) - Proc. 305210/2018-1. RS acknowledges support by the DFG German Research Foundation (project 446102036). We also would like to thanks the referee, Alex B Davis, for a suggestion that impro v ed the paper

Retrieval methods of effective cloud cover from the GOME instrument: an intercomparison

The radiative scattering by clouds leads to errors in the retrieval of column densities and concentration profiles of atmospheric trace gas species from satellites. Moreover, the presence of clouds changes the UV actinic flux and the photo-dissociation rates of various species significantly. The Global Ozone Monitoring Experiment (GOME) instrument on the ERS-2 satellite, principally designed to retrieve trace gases in the atmosphere, is also capable of detecting clouds. Four cloud fraction retrieval methods for GOME data that have been developed are discussed in this paper (the Initial Cloud Fitting Algorithm, the PMD Cloud Recognition Algorithm, the Optical Cloud Recognition Algorithm (an in-house version and the official implementation) and the Fast Retrieval Scheme for Clouds from the Oxygen A-band). Their results of cloud fraction retrieval are compared to each-other and also to synoptic surface observations. It is shown that all studied retrieval methods calculate an effective cloud fraction that is related to a cloud with a high optical thickness. Generally, we found ICFA to produce the lowest cloud fractions, followed by our in-house OCRA implementation, FRESCO, PC2K and finally the official OCRA implementation along four processed tracks (+2%, +10%, +15% and +25% compared to ICFA respectively). Synoptical surface observations gave the highest absolute cloud fraction when compared with individual PMD sub-pixels of roughly the same size