Space Frontier Research Articles

The gravity of it all: From osteoporosis to immunosuppression, exploring disease in a microgravity environment holds promise for better treatments on Earth.

Today, exploration into the universe beyond our planet takes many forms and has led to fascinating discoveries in the life and physical sciences, many of which inform our understanding of health and medicine here on Earth. These new voyages of discovery include telescopes that peer deep into space and time, rovers that crawl about on other planets, and, most remarkably, a permanently crewed orbital outpost: the International Space Station (ISS). Like the voyages of discovery long ago, the ISS is a ship with human pioneers looking outward to the next horizon, exploring the physical universe beyond?but also inward, to define the limits of our existence when living in the new frontier of space.

The Lawless Frontier of Deep Space: Code as Law in EVE Online

This article explores the concepts of player agency with respect to governance and regulation of online games. It considers the unique example of the Council of Stellar Management in EVE Online, and explores the multifaceted role performed by players involved in that Council. In particular, it considers the interaction between code, rules, contracts, and play with respect to EVE Online. This is used as a means to better understand the relations of power generated in game spaces.

The Ineluctable Outer Space for India's National Security

Outer space, or simply space, is the void that exists between celestial bodies. This frontier of outer space is fast emerging as the fourth dimension (after land, sea and air) for military applications. Space will undoubtedly be the military high ground for warfare in the future acting as a “force multiplier” for any military operation. Militarization of space involves use of space technology for exploiting weapons on the ground and in the earth's atmosphere with more accuracy. India has to defend her physical, economic and cultural identity in the prevalent geo-political milieu as it faces varied and complex security challenges. There is a clear and present danger that sooner or later space could be weaponized by various countries. India can no longer be immune to the rapidly changing international security environment, threat to India's national security from nuclear and missile capabilities in its neighbourhood and the vulnerabilities of its space assets. It is therefore imperative that India exploits the capabilities of space, concurrently at appropriate levels, to achieve the desired operational capabilities in a compressed time frame. Since the early 1990s, the Indian armed forces have benefitted from the Indian Space Research Organisation (ISRO) civilian satellites. However, as operational requirements now demand an increase in military capabilities, the armed forces certainly need dedicated military satellites. This space capability has to be optimally exploited by the three services of the Indian defence forces with synergy and harmony, which is possible only under a single appropriate command structure. It is high time that India realizes: “To remain in Race, the Indian armed forces should be in Space”.

Multi-objective optimization of coal-fired power plants using differential evolution

The design trade-offs between thermodynamics and economics for thermal systems can be studied with the aid of multi-objective optimization techniques. The investment costs usually increase with increasing thermodynamic performance of a system. In this paper, an enhanced differential evolution with diversity-preserving and density-adjusting mechanisms, and a newly-proposed algorithm for searching the decision space frontier in a single run were used, to conduct the multi-objective optimization of large-scale, supercritical coal-fired plants. The uncertainties associated with cost functions were discussed by analyzing the sensitivity of the decision space frontier to some significant parameters involved in cost functions. Comparisons made with the aid of an exergoeconomic analysis between the cost minimum designs and a real industrial design demonstrated how the plant improvement was achieved. It is concluded that the cost of electricity could be reduced by a 2–4%, whereas the efficiency could be increased by up to two percentage points. The largest uncertainty is introduced by the temperature-related and reheat-related cost coefficients of the steam generator. More reliable data on the price prediction of future advanced materials should be used to obtain more accurate fronts of the objective space.

Movimentos de ocupação urbana: uma integração teórica através do Conceito de Happening

This article discusses urban occupations as dynamics of discourse that compose meanings and senses to the public space, through the conception of happening. It seeks to explain the dialogic processes that occur in these events and that occur in these manifestations and that count on the contribution of several psychological, cultural and historical factors. Therefore, it is the urban setting as one of the vectors that contributes to the formation of the narratives in the city, and they urge us to think about the relations of appropriation of space as creating places of experience in the social context. These events are understood as a means of interaction that put in challenge issues such as collective space and freedom of expression, a kind of communicational space frontier, in a dialogical construction. In this di­rection it constitutes the metropolis while rebuilding the environment in which subjectivities, in interactions of iden­tification and differentiation that create a dynamic construction of the notion of the self and the other. It is thought of the urban manifestations as happenings, in which the construction of otherness and therefore the relational identity gets involved with social processes with more far reaching, occupying a space of communicational frontier.

The Strange Case of Dr. von Braun and Mr. Disney: Frontierland, Tomorrowland, and America’s Final Frontier

Abstract:When Disneyland opened in 1955, it featured America’s past in Frontierland and looked at America’s future in Tomorrowland. Together they represent what scholar of religion Mircea Eliade called a “religious nostalgia” for a mythic past; in this case, a nostalgia for the western frontier. The conjoining of space exploration with the historical frontier solidified space as America’s new frontier in the popular imagination and a sense of being called by God to explore the new frontier of outer space. Disney’s Tomorrowland, in tension with Frontierland, paralleled how nostalgia for the western frontier was revived as faith in the future.

Portfolio Optimization with Quasiconvex Risk Measures

In this paper, we focus on the portfolio optimization problem associated with a quasiconvex risk measure (satisfying some additional assumptions). For coherent/convex risk measures, the portfolio optimization problem has been already studied in the literature. Following the approach of Ruszczyński and Shapiro [Ruszczyński A, Shapiro A (2006) Optimization of convex risk functions. Math. Oper. Res. 31(3):433–452.], but by means of quasiconvex analysis and notions of subdifferentiability, we characterize optimal solutions of the portfolio problem associated with quasiconvex risk measures. The shape of the efficient frontier in the mean-risk space and some particular cases are also investigated.

Portfolio Optimization with Quasiconvex Risk Measures

In this paper, we focus on the portfolio optimization problem associated to a quasiconvex risk measure (satisfying some additional assumptions). For coherent/convex risk measures, the portfolio optimization problem has been already studied by Gaivoronski and Pflug (2005), Rockafellar and Uryasev (2000) and Ruszczynski and Shapiro (2006), among others. Following the approach of Ruszczynski and Shapiro (2006) but by means of quasiconvex analysis and notions of subdifferentiability, we characterize optimal solutions of the portfolio problem associated to quasiconvex risk measures. The shape of the efficient frontier in the mean-risk space and some particular cases are also investigated.

The Digital David and the Gutenberg Goliath: The Rise of the ‘Enhanced’ e-book

In the recent past, the large-scale production and marketing of e-reading devices, such as Amazon's Kindle, and tablet computers, such as Apple's iPad, have allowed literary works to be presented in a digital reading space, both in the form of standard e-books and, more recently, as enhanced or ‘amplified’ e-books. Given the rapid rise of the Digital Humanities in the world academy, these products have gained a new prominence, despite continuing fears among literary guardians that the digital reading space might cause fluency disruptions and break the hermeneutic immersion necessary for strong, deep reading. For such scholars, digital reading is seen as irrevocably altering the traditional, paper-based reading experience. It is necessary, however, to acknowledge that the reading landscape has shifted decisively towards the digital sphere, and that the new digital reader – the so-called digital native – absorbs information almost exclusively in a digital, hyperconnected space. How do some of the literary products on the frontier of the digital reading space ‘measure up’? Is there room enough only in the nonfiction and educational genres for a digital evolution, as predicted by many publishers and academics, or will fiction, too, absorb digital media into its storytelling praxis?

Structure-Guided Deimmunization of Therapeutic Proteins

Therapeutic proteins continue to yield revolutionary new treatments for a growing spectrum of human disease, but the development of these powerful drugs requires solving a unique set of challenges. For instance, it is increasingly apparent that mitigating potential anti-therapeutic immune responses, driven by molecular recognition of a therapeutic protein's peptide fragments, may be best accomplished early in the drug development process. One may eliminate immunogenic peptide fragments by mutating the cognate amino acid sequences, but deimmunizing mutations are constrained by the need for a folded, stable, and functional protein structure. These two concerns may be competing, as the mutations that are best at reducing immunogenicity often involve amino acids that are substantially different physicochemically. We develop a novel approach, called EpiSweep, that simultaneously optimizes both concerns. Our algorithm identifies sets of mutations making such Pareto optimal trade-offs between structure and immunogenicity, embodied by a molecular mechanics energy function and a T-cell epitope predictor, respectively. EpiSweep integrates structure-based protein design, sequence-based protein deimmunization, and algorithms for finding the Pareto frontier of a design space. While structure-based protein design is NP-hard, we employ integer programming techniques that are efficient in practice. Furthermore, EpiSweep only invokes the optimizer once per identified Pareto optimal design. We show that EpiSweep designs of regions of the therapeutics erythropoietin and staphylokinase are predicted to outperform previous experimental efforts. We also demonstrate EpiSweep's capacity for deimmunization of the entire proteins, case analyses involving dozens of predicted epitopes, and tens of thousands of unique side-chain interactions. Ultimately, Epi-Sweep is a powerful protein design tool that guides the protein engineer toward the most promising immunotolerant biotherapeutic candidates.

Attribute index and uniform design based multiobjective association rule mining with evolutionary algorithm.

In association rule mining, evaluating an association rule needs to repeatedly scan database to compare the whole database with the antecedent, consequent of a rule and the whole rule. In order to decrease the number of comparisons and time consuming, we present an attribute index strategy. It only needs to scan database once to create the attribute index of each attribute. Then all metrics values to evaluate an association rule do not need to scan database any further, but acquire data only by means of the attribute indices. The paper visualizes association rule mining as a multiobjective problem rather than a single objective one. In order to make the acquired solutions scatter uniformly toward the Pareto frontier in the objective space, elitism policy and uniform design are introduced. The paper presents the algorithm of attribute index and uniform design based multiobjective association rule mining with evolutionary algorithm, abbreviated as IUARMMEA. It does not require the user-specified minimum support and minimum confidence anymore, but uses a simple attribute index. It uses a well-designed real encoding so as to extend its application scope. Experiments performed on several databases demonstrate that the proposed algorithm has excellent performance, and it can significantly reduce the number of comparisons and time consumption.

Optimization design of the stratospheric airship’s power system based on the methodology of orthogonal experiment

The optimization design of the power system is essential for stratospheric airships with paradoxical requirements of high reliability and low weight. The methodology of orthogonal experiment is presented to deal with the problem of the optimi- zation design of the airship's power system. Mathematical models of the solar array, regenerative fuel cell, and power management subsystem (PMS) are presented. The basic theory of the method of orthogonal experiment is discussed, and the selection of factors and levels of the experiment and the choice of the evaluation function are also revealed. The proposed methodology is validated in the optimization design of the power system of the ZhiYuan-2 stratospheric airship. Results show that the optimal configuration is easily obtained through this methodology. Furthermore, the optimal configuration and three sub-optimal configurations are in the Pareto frontier of the design space. Sensitivity analyses for the weight and reliability of the airship's power system are presented.

Size-velocity correlations in hybrid high order moment/multi-fluid methods for polydisperse evaporating sprays: Modeling and numerical issues

Kah et al. (2010) [30,33] recently developed the Eulerian multi-size moment model (EMSM) which tackles the modeling and numerical simulation of polydisperse multiphase flows. Using a high order moment method in a compact interval, they suggested to reconstruct the number density function (NDF) by entropy maximization, which leads to a unique and realizable NDF, potentially in several size intervals, thus leading to an hybrid method between Multifluid and high order. This reconstruction is used to simulate the evaporation process, by an evaluation of the flux of droplet disappearance at zero size, the fluxes of droplets between size intervals, and an accurate description of the size shift induced by evaporation Massot et al. (2010) [15]. Although this method demonstrated its potential for evaporating polydisperse flows, two issues remain to be addressed. First, the EMSM only considers one velocity for all droplets, thus decoupling size from velocity, which is too restrictive for distributions with a large size spectrum. In most applications size-conditioned dynamics have to be accounted for. Second, the possibility to have separated dynamics for each size can lead to quasi-monodisperse distributions, which corresponds to a hard limiting case for the EM algorithm. So the behavior of the algorithm needs to be investigated, in order to reproduce the entire moment space with a reasonable accuracy. The aim of this paper is thus twofold. The EM and its related algorithm are enhanced by using a more accurate integration method in order to handle NDF close to the frontier of the moment space associated with an adaptive number of parameters to reconstruct the NDF accurately and efficiently, as well as tabulated initial guess to optimize the computational time. Then, a new model called CSVM (coupled size-velocity moments model) is introduced. Size-velocity correlations are addressed either in the evaporation and drag processes, or in the convective transport. To reach this goal, a velocity reconstruction for each size is suggested, using only one additional moment per dimension, and which can be directly applied to several size intervals. Thus, this method is a direct generalization of EMSM. To handle the convective transport, a flux splitting scheme is proposed, based on the underlying kinetic description of the disperse phase. Comparing to existing approaches, a main novelty of the CSVM is that our kinetic approach ensures built-in realizability conditions, no additional corrections of the moments being needed at each time step. The full strategy is first evaluated in 0D and 1D cases, which either demonstrates the ability to reproduce both evaporation, drag force and convection with size-velocity correlations, or the possible extension to several size intervals. Finally, the method is applied on 2D cases with only one section, showing the ability of the CSVM and its related algorithms to capture the main physics of polydisperse evaporating sprays with a minimal number of moments.

Commercial Space Tourism and Space Weather: An Update

Commercial Space Tourism and Space Weather: An Update

Analysis of Pareto frontiers for multidisciplinary design optimization of aircraft

The goal of this work is the development of a methodology and a computational environment to enable a Pareto frontier analysis for the preliminary design optimization of a wing/horizontal tail/fuselage aircraft configuration. Integrated Multidisciplinary Design Optimization (MDO) is used to minimize a composite multi-objective function. A Pareto frontier in the 3D objective space of weight (minimum), aerodynamic efficiency (maximum), and mission range (maximum) is constructed for the actual configuration of a regional aircraft. MDO techniques improve upon the obtained solution compared to classical sequential design, as they account for all interactions and influences between the disciplines under investigation. The multi-objective problem is solved by generating a set of Pareto optimal solutions that constitute a Pareto frontier. Three different formulations of the Weighed Global Criterion (WGC) method are used, and these functional formulations are analyzed and the concept of a local approximation function is developed to build the Pareto frontier. The developed algorithm uses a commercial optimization code and a commercial finite element code to perform the required analyses. Finally, a criterion for selecting an ultimate design solution for the aircraft on the Pareto frontier is addressed.

Trends in the global space arena – Impact on Africa and Africa's response

Since the establishment of the United Nations Committee on the Peaceful Exploration and Uses of Outer Space (COPUOS) in 1959, many actions that affect the advancement of the space frontier have been taken, within and outside COPUOS, in the interest of the global community, but without much input from Africa. Yet a number of African countries have joined those with assets in space, albeit without the necessary infrastructure on the ground. These actions vary in scope, in importance and in participation; however, they affect us all. Examples include the legal instruments that are in operation today for the exploration and peaceful uses of outer space, sustainability of the outer space environment and the Global Exploration Strategy– Framework for Coordination (GES–FC), conceived by 14 spacefaring nations; this laid out the details needed for an active global space exploration programme. This paper reflects on existing space-related regional cooperation arrangements at the inter-governmental level, including the African Leadership Conference on Space Science and Technology for Sustainable Development (ALC). Noting that, despite UN General Assembly endorsement of the need for developing countries to have access to the International Space Station (ISS), almost all in Africa have not, it asks what Africa might gain from such an experience. The paper concludes with an examination of where and why Africa needs to focus its immediate space-related efforts – on the ground here on Earth or in outer space?

Space chronicles: facing the ultimate frontier

America's space program is at a turning point. After decades of global primacy, NASA has ended the space-shuttle program, cutting off its access to space. No astronauts will be launched in an American craft, from American soil, until the 2020s, and NASA may soon find itself eclipsed by other countries' space programs. With his signature wit and thought-provoking insights, Neil deGrasse Tyson-one of our foremost thinkers on all things space-illuminates the past, present, and future of space exploration and brilliantly reminds us why NASA matters now as much as ever. As Tyson reveals, exploring the space frontier can profoundly enrich many aspects of our daily lives, from education systems and the economy to national security and morale. For America to maintain its status as a global leader and a technological innovator, he explains, we must regain our enthusiasm and curiosity about what lies beyond our world. Provocative, humorous, and wonderfully readable, Space Chronicles represents the best of Tyson's recent commentary, including a must-read prologue on NASA and partisan politics. Reflecting on topics that range from scientific literacy to space-travel missteps, Tyson gives us an urgent, clear-eyed, and ultimately inspiring vision for the future.

Nonparametric measurement of the overall shift in the technology frontier: an application to multiple-output agricultural production data in the Brazilian Amazon

This article develops a simple, but informative, approach to measure technical changes by applying the Malmquist index framework using data envelopment analysis (DEA). A set of directional vectors is used to capture complete information regarding the overall shift in the technology frontier; we then visualize the DEA frontiers in the output space. This approach deals with the problems of sample dependence and non-circularity of technical change measures. It allows us to measure output-by-output technical change. Furthermore, the geometric mean of the technical change measures derived using this approach satisfies circularity. The application of Malmquist indices to the panel datasets of agricultural production in the Brazilian Amazon during the period 1975–1995 indicates a non-Hicks-neutral technical change, with intersection of frontiers during both the 1975–1985 and the 1985–1995 sub-periods. We find moderate progress in cattle production and annual crops, and a decline in perennial crops (bananas). Technological progress is a modest 0.7% during the period 1975–1995 on average. In addition, comparisons with the sample-dependent measures in the preceding studies demonstrate that these indices are usually sensitive to the distribution of actual sampled data points.

A Method to Estimate Power Parameter in Exponential Power Distribution Via Polynomial Regression

The Exponential Power Distribution (EPD), also known as Generalized Error Distribution (GED), is a flexible symmetrical unimodal family belonging to the exponential family. The EPD becomes the density function of a range of symmetric distributions with different values of its power parameter B. A closed-form estimator for B does not exist, so the power parameter is usually estimated numerically. Unfortunately the optimization algorithms do not always converge, especially when the true value of B is close to its parametric space frontier. In this paper we present an alternative method for estimating B, based on the Normal Standardized Q-Q Plot and exploiting the relationship between B and the kurtosis. It is a direct method that does not require computational efforts or the use of optimization algorithms.

A method to estimate power parameter in exponential power distribution via polynomial regression

The exponential power distribution (EPD), also known as generalized error distribution, is a flexible symmetrical unimodal family that belongs to the exponential one. The EPD becomes the density function of a range of symmetric distributions with different values of its power parameter β. A closed-form estimator for β does not exist, so the power parameter is usually estimated numerically. Unfortunately, the optimization algorithms do not always converge, especially when the true value of β is close to its parametric space frontier. In this paper, we present an alternative method to estimate β. Our proposal is based on the normal standardized Q–Q plot, and it exploits the relationship between β and the kurtosis. Furthermore, it is a direct method which does not require computational efforts nor the use of optimization algorithms.