208 research outputs found
Assessment of the Current Life Support System and Well-being on the International Space Station for a Sustainable Space Exploration
No full textShuichi Ichimura, Kyoto University, JapanYosuke A. Yamashiki, Kyoto University, JapanICES501: Life Support Systems Engineering and AnalysisThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.Life support systems in space have progressed
significantly, enabling partial recovery of oxygen and
water. Despite these advancements, human space missions
remain heavily reliant on resupply missions to deliver
essential resources, such as gas tanks, water bags, and
food from Earth. Achieving sustainable human space
exploration necessitates addressing both technical
challenges and the well-being of astronauts. This research
examines the current state of critical life support
elements—air, water, and food—as well as well-being factors
such as clothing, hygiene, and healthcare by analyzing
actual resupply data for the International Space Station
(ISS). Key findings reveal that resupply missions not only
deliver consumables like gas tanks and water bags but also
a significant volume of spare parts for maintaining
recovery systems. Food supplies, in particular, remain
entirely dependent on resupply missions. For well-being
elements, while the quantity of delivered supplies meets
the standards set by space agencies, astronauts report
discomfort with prolonged use of items such as clothing and
towels, especially exercise apparel, which develops
persistent unpleasant odors over time. The analysis also
identifies inefficiencies in resupply operations. Delivered
consumables and equipment constitute only 0.21% of the
total launch mass, highlighting the logistical challenges
of these missions. Dependence on frequent resupply missions
introduces physical and psychological challenges, including
risks of resource shortages, limited storage space
exacerbated by accumulating waste, odor management issues,
and stress from the complex cargo unloading and reloading.
As humanity sets its sights on exploration to the Moon and
beyond, the feasibility of frequent resupply missions
diminishes due to increased costs and extended delivery
times. This research emphasizes the urgent need for
advanced technologies to support sustainable human presence
in space. Proposed solutions include closed-loop life
support systems, innovative waste management strategies,
and improved designs to enhance astronaut comfort and
well-being during long-duration missions
New Insights on the (Non-)Hardness of Circuit Minimization and Related Problems
No full textThe Minimum Circuit Size Problem (MCSP) and a related problem (MKTP) that deals with time-bounded Kolmogorov complexity are prominent candidates for NP-intermediate status. We show that, under very modest cryptographic assumptions (such as the existence of one-way functions), the problem of approximating the minimum circuit size (or time-bounded Kolmogorov complexity) within a factor of n1−o(1) is indeed NP-intermediate. To the best of our knowledge, these problems are the first natural NP-intermediate problems under the existence of an arbitrary one-way function.
We also prove that MKTP is hard for the complexity class DET under non-uniform NC0 reductions.
This is surprising, since prior work on MCSP and MKTP had highlighted weaknesses of “local” reductions such as NC0-many-one reductions. We exploit this local reduction to obtain several new consequences:
* MKTP is not in AC0[p].
* Circuit size lower bounds are equivalent to hardness of a relativized version MKTPA of MKTP under a class of uniform AC0 reductions, for a large class of sets A.
* Hardness of MCSPA implies hardness of MKTPA for a wide class of sets A. This is the first result directly relating the complexity of MCSPA and MKTPA, for any A.Paper presented at the 42nd International Symposium on Mathematical Foundations of Computer Science, August 21-25, 2017, Aalborg, Denmark. This is the Author’s Original, a longer and more complete version of the paper published in: Larsen, K.G., Bodlaender, H.L., & Raskin, J.-F. (Eds.). (2017). Proceedings from 42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017). Dagstuhl, Germany: Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik. (Leibniz International Proceedings in Informatics (LIPIcs)). DOI: 10.4230/LIPIcs.MFCS.2017.54.Peer reviewed
New insights on the (non-)hardness of circuit minimization and related problems
No full textThe Minimum Circuit Size Problem (MCSP) and a related problem (MKTP) that deals with time-bounded Kolmogorov complexity are prominent candidates for NP-intermediate status. We show that, under very modest cryptographic assumptions (such as the existence of one-way functions), the problem of approximating the minimum circuit size (or time-b^ounded Kolmogorov complexity) within a factor of n^{1−o(1)} is indeed NPintermediate. To the best of our knowledge, these problems are the first natural NP-intermediate problems under the existence of an arbitrary one-way function. Our technique is quite general; we use it also to show that approximating the size of the largest clique in a graph within a factor of n^{1−o(1)} is also NP-intermediate unless NP ⊆ P/poly.
We also prove that MKTP is hard for the complexity class DET under non-uniform NC0 reductions. This
is surprising, since prior work on MCSP and MKTP had highlighted weaknesses of “local” reductions such as NC0 reductions . We exploit this local reduction to obtain several new consequences:
—MKTP is not in AC0[p].
—Circuit size lower bounds are equivalent to hardness of a relativized version MKTP^A of MKTP under a class of uniform AC0 reductions, for a significant class of sets A.
—Hardness of MCSP^A implies hardness of MKTP^A for a significant class of sets A. This is the first result directly relating the complexity of MCSP^A and MKTP^A, for any A.Peer reviewed© ACM, 2019. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM Transactions on Computation Theory (TOCT), {Vol.11, Iss.4, (September 2019)} http://doi.acm.org/10.1145/3349616
A comparative study of real options valuation methods : economics-based approach vs. engineering-based approach
No full textThesis (S.M. in Real Estate Development)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 74-76).It has been expected that the option valuation theory will play a much more significant role in the real estate analysis. However, potentially because of the need for understanding the advanced financial theories, the real options analysis has not been fully used in the real world. In order to attack this problem, it is highly desired to create a more practical and easily understandable calculation model for valuing flexibility. With the increasing computational power of today, an interesting approach to valuing flexibility arises from the field of engineering systems. This approach does not require the understanding of advanced financial theories, and aims to assess the value of flexibility built into the project design. Although the perspective of this approach may be slightly different from that of traditional real options valuation approach, this approach might be an alternative method as a simpler model for valuing flexibility. The comparative study of the economics-based approach and the engineering-based approach revealed that the latter approach has one critical problem in estimating the value of flexibility; the usage of a single risk-adjusted discount rate leads to either underestimation or overestimation of the real options value. Based on the results of a case study, this thesis proposes to use the engineering-based approach together with the economics-based approach. With its ability of comprehensive analysis and graphic presentation, the engineering-based approach has a great probability to make it easier for average practitioners to intuitively understand the value of flexibility.by Shuichi Masunaga.S.M.in Real Estate Developmen
Volumetric trans-scale imaging of massive quantity of heterogeneous cell populations in centimeter-wide tissue and embryo
No full textIchimura Taro, Kakizuka Taishi, Sato Yuki, et al. Volumetric trans-scale imaging of massive quantity of heterogeneous cell populations in centimeter-wide tissue and embryo. eLife 493, 318 (2024); https://doi.org/10.7554/eLife.93633.We established a volumetric trans-scale imaging system with an ultra-large field-of-view (FOV) that enables simultaneous observation of millions of cellular dynamics in centimeter-wide three-dimensional (3D) tissues and embryos. Using a custom-made giant lens system with a magnification of 2× and a numerical aperture (NA) of 0.25, and a CMOS camera with more than 100 megapixels, we built a trans-scale scope AMATERAS-2, and realized fluorescence imaging with a lateral spatial resolution of approximately 1.2 µm across an FOV of approximately 1.5 × 1.0 cm2. The 3D resolving capability was realized through a combination of optical and computational sectioning techniques tailored for our low-power imaging system. We applied the imaging technique to 1.2 cm-wide section of mouse brain, and successfully observed various regions of the brain with sub-cellular resolution in a single FOV. We also performed time-lapse imaging of a 1-cm-wide vascular network during quail embryo development for over 24 hours, visualizing the movement of over 4.0 × 105 vascular endothelial cells and quantitatively analyzing their dynamics. Our results demonstrate the potential of this technique in accelerating production of comprehensive reference maps of all cells in organisms and tissues, which contributes to understanding developmental processes, brain functions, and pathogenesis of disease, as well as high-throughput quality check of tissues used for transplantation medicine
A Display of Constellations by a Microcomputer
No full textThe author displayed constellations by a microcomputer in his lecture in the astronomy of the ancient China for the undergraduate students. For the first display, a programme devised by Shuichi Nakano (1980) was used. The remarks made by the students were varied. However, the improvements which many of the students suggested were the following two : (1) reduction the time required for the display and (2) display of transition of constellations by diurnal motion or annual motion. After a week the second display was made on the new programme: the time for display was reduced from 3. 24mn to 1.50mn. The improvement made the students' impression quite favorable.departmental bulletin pape
Non-Gender-Phase in Park Life
No full textYOSHIDA Shuichi is the author of Park life, which won the 127th Akutagawa Literary Award. This could be categorized as one of his works on the "present-day superficial human-relations" and "a sense of distance of a person and a person." Particularly about such relationships, he is recognized to have a delicate sense of gender. In this paper, extracting some , I made a attempt to examine the non-gender phase seen in Park Life from the point of view of "a sense of distance".departmental bulletin pape
Generalized Littlewood–Paley characterizations of fractional Sobolev spaces
No full textIn this paper, the authors characterize the Sobolev spaces (Formula presented.) with (Formula presented.) and (Formula presented.) via a generalized Lusin area function and its corresponding Littlewood–Paley (Formula presented.)-function. The range (Formula presented.) is also proved to be nearly sharp in the sense that these new characterizations are not true when (Formula presented.) and (Formula presented.). Moreover, in the endpoint case (Formula presented.), the authors also obtain some weak type estimates. Since these generalized Littlewood–Paley functions are of wide generality, these results provide some new choices for introducing the notions of fractional Sobolev spaces on metric measure spaces. © 2017 World Scientific Publishing CompanyEmbargo Period 12 months金沢大学人間社会研究域学校教育系journal articl
On Behaviors of Cellular Automata with Rule 165
No full textThis paper deals with one-dimensional finite cellular automata with a triplet local transition rule 156 and fixed boundary conditions. The author observed behaviors of CA-156 000 (m) by computer, and found formulae of number of limit cycles and transient length from observation. And the author got proof of them. 1 Introduction J. von Neumann introduced cellular automata capable of self-reproduction and universal computation. While cellular automata have simple structure, their global behaviors caused by interactions between cells are very complicated. Their global behaviors are similar to behaviors of complex systems as fractals, chaotic phenomenon and so on. S. Wolfram and other researchers rerealized important roles of cellular automata as theoretical models of complex systems. Cellular automata have wide applications in biology, physics, computer science, mathematics and so on. Recently various cellular automata are investigated and applied by many researchers. S. Wolfram classifie..
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