1,150 research outputs found
Computationally driven discovery of layered quinary oxychalcogenides: Potential p-type transparent conductors?
No full textSummary: n-type transparent conductors (TCs) are key materials in the modern optoelectronics industry. Despite years of research, the development of a high-performance p-type TC has lagged far behind that of its n-type counterparts, delaying the advent of “transparent electronics”-based p-n junctions. Here, we propose the layered oxysulfide [Cu 2S 2][Sr 3Sc 2O 5] as a structural motif for discovering p-type TCs. We have used density functional theory to screen 24 compositions based on this motif in terms of their thermodynamic and dynamic stability and their electronic structure, thus predicting two p-type TCs and eight other stable systems with semiconductor properties. Following our predictions, we have successfully synthesized our best candidate p-type TC, [Cu 2S 2][Ba 3Sc 2O 5], which displays structural and optical properties that validate our computational models. It is expected that the design principles emanating from this analysis will move the field closer to the realization of a high figure-of-merit p-type TC.Progress and Potential: This work has predicted and experimentally realized the p-type transparent conductor [Cu 2S 2][Ba 3Sc 2O 5], and at the same time has developed design principles for layered oxychalcogenide materials of this structure type. The layered oxychalcogenide materials offer a large configurational space of potentially stable compounds with tunable functional properties for a wide range of applications. The longer-term ambitions of the research are to use the combined methods of density functional theory and experiments to search for and understand further layered oxychalcogenide structure types and configurations for different semiconductor applications. This research has the potential to affect the types of electronic devices by bringing us closer to the realism of transparent electronics. The research presented will also further the development of applications for which transparent conductors are essential, such as solar cells. Abstract: The realization of transparent electronics is hindered by the lack of a suitable high-mobility p-type transparent conductor (TC). This work used ab initio simulations to search for a p-type TC based on the layered oxychalcogenide [Cu 2S 2][A 3M 2O 5] structure. The main result of this study was the discovery of the optimum p-type oxychalcogenide TC, [Cu 2S 2][Ba 3Sc 2O 5], predicted to have a higher optical band gap, better hole mobility, and greater stability than its parent compound [Cu 2S 2][Ba 3Sc 2O 5]; this was verified experimentally. </p
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GJ 3929: High-precision Photometric and Doppler Characterization of an Exo-Venus and Its Hot, Mini-Neptune-mass Companion
No full textWe detail the follow-up and characterization of a transiting exo-Venus identified by TESS, GJ 3929b (TOI-2013b), and its nontransiting companion planet, GJ 3929c (TOI-2013c). GJ 3929b is an Earth-sized exoplanet in its star’s Venus zone (P b = 2.616272 ± 0.000005 days; Sb = 17.3 − 0.7 + 0.8 S ⊕) orbiting a nearby M dwarf. GJ 3929c is most likely a nontransiting sub-Neptune. Using the new, ultraprecise NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak National Observatory, we are able to modify the mass constraints of planet b reported in previous works and consequently improve the significance of the mass measurement to almost 4σ confidence (M b = 1.75 ± 0.45 M ⊕). We further adjust the orbital period of planet c from its alias at 14.30 ± 0.03 days to the likely true period of 15.04 ± 0.03 days, and we adjust its minimum mass to m sin i = 5.71 ± 0.92 M ⊕. Using the diffuser-assisted ARCTIC imager on the ARC 3.5 m telescope at Apache Point Observatory, in addition to publicly available TESS and LCOGT photometry, we are able to constrain the radius of planet b to R p = 1.09 ± 0.04 R ⊕. GJ 3929b is a top candidate for transmission spectroscopy in its size regime (TSM = 14 ± 4), and future atmospheric studies of GJ 3929b stand to shed light on the nature of small planets orbiting M dwarfs. © 2022. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Observation of an order of magnitude increase in the rate photocatalysis for hierarchically porous anatase films synthesized from zinc titanate coatings
No full textIn this paper we report on the use of aerosol assisted chemical vapour deposition (AACVD) to form thin films of the zinc titanate phases using zinc acetate and titanium isopropoxide as precursors in methanol solution. Analysis by XRD and XPS found that through variation in experimental conditions we have been able to synthesize films of zinc titanate with composition of Zn2TiO4 or Zn0.3Ti2.7O4.94, which adopt the spinel and pseudobrookite structure respectively. In addition, we have also formed hybrid films of Zn2TiO4 with either ZnTiO3 or ZnO. Using a technique previously reported with powders, the mixed ZnO and Zn2TiO4 films were treated with acid to produce porous Zn2TiO4 which, through reduction and vapour leaching of zinc, were converted to hierarchically porous thin films of anatase TiO2. This conversion was monitored by XRD. Analysis of photocatalytic activity of the hierarchically porous titania, using dye and stearic acid degradation tests, found a factor of 12 to 14 increase in rates of photocatalysis over conventional TiO2 thin films. Finally we are able to report a maximum formal quantum efficiency for stearic acid degradation of 1.76 × 10-3 molecules per photon
The Optimization of the Performance Management for Operators in GJ Company Xiamen
No full text本文以绩效管理的基本理论和GJ厦门厂的实际情况为基础，分析了GJ厦门厂一线作业员绩效管理的问题点，并结合公司目前的实际情况提出一线作业员的绩效管理改善方案。该方案以平衡计分卡的绩效管理体系为逻辑，将公司的战略目标分解到制造处，再分解至一线作业员，让作业员的绩效也能从财务面、客户面、内部运营面、学习成长面四个维度上对公司的战略发展起到支撑作用，以促进组织战略目标的实现。 在绩效管理改进方案中，作者特别强调沟通在绩效管理过程中的重要作用，它贯穿了绩效管理的整个过程。沟通有助于促进员工个人绩效的提升和员工个人的成长，从而提升组织的整体效益。 根据GJ厦门厂的实际情况，将一线作业员的绩效考核结...In this paper, operators’ performance management problems in GJ Company are analyzed based on the basic theory of performance management and the real situation of the company. The author propose to break down the company’s strategic targets to lower levels with balanced scorecard system by four levels of financial, customer, internal operation, learning and developing. So that operators’ performa...学位：管理学硕士院系专业：管理学院_工商管理硕士(工商管理硕士)学号：1792012115103
Exergy comparison of lunar propellant manufacturing and insertion into LEO using a fully reusable refueling rocket
No full textQuantifying the exergy requirement of propellant insertion into LEO can lead to insight into the feasibility of a lunar propellant-generating architecture. Spacecraft leaving from Earth can greatly reduce their lift-off mass if in-space refueling would possible. Exergy analyses quantify the available energy of a system and show where a reduction in usable energy occurs. Insight into the exergy destruction and input provides a key parameter into the scaling and design of processes and corresponding power systems. The present study aims to define an exergy environment in the lunar PSRs and then to analyze the exergy destruction related to the production of oxygen, ALICE, and hydrolox, in terms of both manufacturing and transportation using a two-stage fully reusable rocket. Extraction processes for ALICE and hydrolox were selected and analyzed w.r.t. the lunar environment to get an understanding of the exergy input. The behavior and exergy requirements of an LEO propellant depot was described. Two fully reusable two-stage rockets using ALICE and hydrolox were designed and compared based on their payload-to-propellant ratio for the oxygen, ALICE, and hydrolox payloads. The study found that the exergetic cost for the insertion of oxygen, hydrolox, and ALICE in LEO were 1.32 GJ/kg , 1.64 GJ/kg, and GJ/kg and 23.3 GJ/kg, 23.4 GJ/kg and 26.9 GJ/kg for the hydrolox and ALICE rocket, respectively.Aerospace Engineerin
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Double Trouble: Two Transits of the Super-Earth GJ 1132 b Observed with JWST NIRSpec G395H
No full textThe search for rocky planet atmospheres with JWST has focused on planets transiting M dwarfs. Such planets have favorable planet-to-star size ratios, enhancing the amplitude of atmospheric features. Since the expected signal strength of atmospheric features is similar to the single-transit performance of JWST, multiple observations are required to confirm any detection. Here, we present two transit observations of the rocky planet GJ 1132 b with JWST NIRSpec G395H, covering 2.8-5.2 μm. Previous Hubble Space Telescope WFC3 observations of GJ 1132 b were inconclusive, with evidence reported for either an atmosphere or a featureless spectrum based on analyses of the same data set. Our JWST data exhibit substantial differences between the two visits. One transit is consistent with either an H2O-dominated atmosphere containing ∼1% CH4 and trace N2O ( χ ν 2 = 1.13 ) or stellar contamination from unocculted starspots ( χ ν 2 = 1.36 ). However, the second transit is consistent with a featureless spectrum. Neither visit is consistent with a previous report of HCN. Atmospheric variability is unlikely to explain the scale of the observed differences between the visits. Similarly, our out-of-transit stellar spectra show no evidence of changing stellar inhomogeneity between the two visits—observed 8 days apart, only 6.5% of the stellar rotation rate. We further find no evidence of differing instrumental systematic effects between visits. The most plausible explanation is an unlucky random noise draw leading to two significantly discrepant transmission spectra. Our results highlight the importance of multivisit repeatability with JWST prior to claiming atmospheric detections for these small, enigmatic planets. © 2023. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Ves v 5 can establish the diagnosis in patients without detectable specific IgE to wasp venom and a possible north-south difference in Api m 1 sensitization in Europe.
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High sensitivity of CAP-FEIA rVes v 5 and rVes v 1 for diagnosis of Vespula venom allergy. [J Allergy Clin Immunol. 2012
Diagnosing Intermittent Faults
No full textIn this working report we outline how to determine the intermittency parameters gj from the activity matrix A (context: DX’08 paper Abreu, Zoeteweij, Van Gemund). We start with the single fault (SF) case and show that averaging over the error vector e is the exact way. We also show that in this way the probability of obtaining exactly this e vector in A is optimal. This is the key insight that allows us to determine g in the general multiple-fault (MF) case. We formulate the gj problem as a (probability) maximization problem, which we solve using a simple gradient ascent technique.Software Computer TechnologyElectrical Engineering, Mathematics and Computer Scienc
Testing contributor & translator roles - harvest
No full textGJ author, edited to add dc.contributor and dc.contributor.translator; cc-by-nc-n
Agent-Based Modeling of Culture's Consequences for Trade
No full textIn this thesis, culture is interpreted as a property of a group of people who share the meaning they attach to symbols, have a common way of expressing their opinions and feelings, and share value systems to judge what is good or bad. The unwritten rules of a culture govern the interpretation of observations and emotions and how to react appropriately. The rules are embedded in an individuals’ mind, form childhood on, by interactions with group members. People often are not aware of differences between their own unwritten rules and those of people having a different cultural background. This may result in unwarranted distrust or unwarranted trust, with serious consequences for the future of relationships. Cultural differences are known to have their effects on trade. Signals that indicate benevolence and trustworthiness of a trade partner in one’s own culture may be interpreted differently by people having a different cultural background. Hofstede (2001) has identified five dimensions of cultural differences: ? Given ingroup relation with relatives and community members may have a different impact on professional relationships in different cultures. ? The impact of hierarchical relationships on the freedom of action of trade partners may be different across cultures. ? Some cultures are oriented toward cooperation and care-taking; others are oriented toward performance and competition. ? Xenophobia is a wide-spread phenomenon in some cultures, while people in other cultures may be more open to the unknown. ? In some cultures people are anxious to keep up their status and display their societal success, while in other cultures thrift and perseverance are seen as virtues. Cultural differences may have their effects in trade on the acceptability of potential partners, on progress and success of negotiations, and on the extent to which partners live up to the negotiated contracts. In a research project Meijer (2009) developed a gaming simulation to study the role of trust in supply networks of food products. The game is called the TRUST & TRACING game. In this game, the producers are informed about product quality. The other players either have to trust the suppliers on their quality statements, or they can have the products traced by an independent authority, but the latter will cost them a fee. In addition to the financial considerations, they must take into account that showing distrust may bring damage to their relationships. Experiments with human subjects in different cultures have shown that the considerations lead to different actions in different countries. It was also found that the inclination to grab an opportunity to defect was different across countries. The subject of this thesis is a computer simulation of the TRUST & TRACING GAME. The purposes of the computer simulation are: ? Validation of theories about, implemented in models of, the players’ behaviors ? testing of hypotheses about relations of rules of the game and parameters of individual players with aggregated game statistics, ? the design of useful game configurations to be played with human players. In the computer simulation the players’ rolls are realized by software agents. The questions which are answered in this thesis concern the modeling of culture’s consequences for the decisions taken by the agents. Such an agent is a computer program which simulates the behavior of human players. In a multi-agent simulation a group of software agents is acting and interacting simultaneously. Autonomy is an important property of software agents. The agents decide what to do; there is no central computer program that imposes decisions on them. Important functions of agents in the present simulation are to approach new potential trade partners, to negotiate about a transaction and to exchange proposals, and, when the negotiation has ended successfully, to exchange products, and to decide and request a trace to be performed. The agents’ decision mechanisms are implemented according to models and data available from scientific literature. To model the influence of culture on the decision making, an expert systems approach is taken, using the Synthetic Cultures according to Hofstede en Pedersen (1999). To develop an expert system, knowledge engineers represent knowledge about some domain of application as a set of rules that can be interpreted by a computer system. Since culture is considered as a set of rules, such an approach is a natural way to model it. The development of expert systems always is an interdisciplinary project. In this case the work of Geert Hofstede has been used and an expert on this work and on Synthetic Cultures has been involved in the formulation of the rules. Synthetic Cultures are imaginary cultures in which the effects of a single dimension of culture are emphasized, isolated from the effects of the other dimensions. The purpose is to make the differences related to that dimension teachable. In reality the differences may be less pronounced and may be mixed with differences related with the other dimensions. In this thesis an approach has been elaborated to compute the simultaneous effect of several dimensions. The approach is based on the principle of weak disjunction, which implies that, if several dimensions have a similar effect, only the strongest effects counts. For instance, if dimension A would have an effect of 75% and dimension B would have an effect of 25%, then their simultaneous effect would be 75%. Expert systems must at least have face validity. An expert in the domain of application mustaccept the decisions that the system produces and the reasoning that leads to these decisions, as being believable. For this purpose computations for specific cases can be made, of which the results are judged by the expert. Further, the results of sensitivity analysis can be judged by an expert. Sensitivity analysis of a model is performed by studying how model outputs vary in relation with systematic variation of input parameter. In addition to face validity, the model must be tested empirically. To that end outputs from gaming simulations with human participants can be compared with outputs from multi-agent simulations. For example, Meijer et al. (2006) found different outcomes from the TRUST & TRACING game between games played in the United States and in the Netherlands. Compared with the Dutch, American players are found to be more eager to buy top quality products, have a stronger inclination to opportunism, anticipate to a greater extent on their partners to defect, and have a stronger preference for quality certification. These differences where reproduced by the multi-agent simulation. The main question of this research is, whether an expert systems approach is feasible to develop a valid model of cultural differentiation in multi-agent simulations, to be applied in research with gaming simulations. The conclusions are: 1. Effects of dimensions of culture can be modeled as an expert system based on Synthetic Cultures. Modeling the simultaneous effects of several dimensions as an expert system proved not feasible: the complexity exceeded the intellectual powers of both expert and modeler. 2. The simultaneous effect of several dimensions can be modeled by weak disjunction of effects. The results have face validity and have empirically been verified for a limited number of cases. 3. Sensitivity analysis of this model is a complex undertaking if both cultural parameters and other parameters are simultaneously varied, because of the strong interactions between these types of parameters. When only the culture parameters are varied (with a fixed setting of the other parameters), or only the other parameters are varied (in a fixed cultural setting), straightforward sensitivity analysis is feasible. Furthermore, it was found that the sensitivity of aggregate model outputs may greatly differ from sensitivity of individual level outputs: parameters that do not affect the aggregate system performance, may affect results of individual agents. 4. This thesis proves that multi-agent simulation is a potent instrument to be used in research with gaming simulations, in particular for the purpose of validation of behavioral models. A problematic issue is, that similarity of the outputs of gaming simulations and multi-agent simulations is no sound proof that the agent correctly implements the human decision making mechanism. This issue is known as under-determination. A validation method is proposed, which builds on the model’s composed structure. Under-determination can be avoided by separate validation of the components in micro-games. The results of this research contribute to the methodology of cultural adaptation of intelligent software agents. This is relevant for the development of research instruments (like the TRUST & TRACING game), educational and training applications to make people aware of cultural differences, and affective human-computer interfaces in a globalizing world.MediamaticsElectrical Engineering, Mathematics and Computer Scienc
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