scholarly journals Minimax model of transport operations of emergency on-orbit servicing in heliosynchronous orbits

2021 ◽  
Vol 2021 (3) ◽  
pp. 48-56
Author(s):  
Yu.M. Holdshtein ◽  
Keyword(s):  
Special Choice ◽  
System Construction ◽  
Minimax Optimization ◽  
Statistical Estimates ◽  
Emergency Situations ◽  
Maximum Time ◽  
Parking Orbit ◽  
Long Time ◽  
Constrained Minimax ◽  
Time And Energy

Heliosynchronous orbits are attractive for space system construction. As a result, the number of spacecraft operating therein is constantly increasing. To increase their efficiency, timely on-orbit servicing (both scheduled and emergency) is needed. Emergency on-orbit servicing of spacecraft is needed in the case of unforeseen, emergency situations with them. According to available statistical estimates, emergency situations with serviced spacecraft are not frequent. Because of this, serviced spacecraft must be within the reach of a service spacecraft for a long time. In planning emergency on-orbit servicing, the following limitations must be met: the time it takes the service spacecraft to approach any of the serviced spacecraft must not exceed its allowable value, and the service spacecraft’s allowable energy consumption must not be exceeded. This paper addresses the problem of searching for emergency on-orbit servicing that would be allowable in terms of time and energy limitations and would meet technical and economical constraints. The aim of this work is to develop a mathematical constrained optimization model for phasing orbit parameter choice, whose use would allow one to minimize the maximum time of transport operations in emergency on-orbit servicing of a spacecraft group in the region of heliosynchronous orbits. The problem is solved by constrained minimax optimization. What is new is the formulation of a minimax (guaranteeing) criterion for choosing phasing orbit parameters that minimize the maximum time of emergency on-orbit servicing transport operations. In the minimax approach, the problem is formulated as the problem of searching for the best solution such that the result is certain to be attained for any allowable sets of indeterminate factors. The proposed mathematical model may be used in planning emergency on-orbit service operations to minimize the maximum duration of emergency on-orbit servicing transport operations due to a special choice of the service spacecraft phasing and parking orbit parameters.

Ecosan Can Provide Sustainable Sanitation in Emergency Situations with Benefits for the Millennium Development Goals

2006 ◽  
Vol 1 (2) ◽  
Author(s):  
E. v. Münch ◽  
G. Amy ◽  
J. F. Fesselet
Keyword(s):  
Low Income ◽  
Urban Areas ◽  
Millennium Development Goals ◽  
Net Present Value ◽  
Soil Conditions ◽  
Value Analysis ◽  
Emergency Situations ◽  
Long Time ◽  
Development Goals ◽  
Sanitation Systems

This paper describes the potential of ecological sanitation (ecosan) to provide sustainable excreta disposal in emergency situations and in peri-urban areas or slums in developing countries. At the present time, pit latrines are the most common form of excreta disposal both for emergency situations and in low-income peri-urban areas or slums. Although not intended to be a long-term solution, pit latrines provided during emergencies are often used for a long time (more than six months to years). This practice is not sustainable if the area is prone to flooding or there are soil conditions that allow groundwater pollution in areas where groundwater is used for drinking water, to name but two of the main factors. We propose eight criteria for the applicability of ecosan based on analysis of three case studies representing different types of emergency situations. The two most important criteria are awareness and expertise in ecosan within the aid agencies, and availability of standardised, lightweight toilet units that are quick to assemble and easy to transport (e.g. container for faeces, and urine diversion squatting pan made of impact-resistant molded polypropylene). Such toilets could be moved to, or replicated in, other areas in need after the emergency (peri-urban areas or slums). This would provide benefits for Millennium Development Goals achievements (targets on hunger, child mortality, sanitation and slum dwellers) at lower cost than conventional sanitation systems. Costs for sanitation systems should be compared based on the entire system (toilet, transport, treatment, reuse in agriculture), using Net Present Value analysis for capital, and operating and maintenance costs.

Obesity: An Evolutionary Perspective

2012 ◽  
Author(s):  
Robin I.M. Dunbar
Keyword(s):  
Body Size ◽  
Evolutionary Perspective ◽  
Long Time ◽  
Human Adults ◽  
Human Brains ◽  
Time And Energy ◽  
Post Industrial ◽  
Industrial Societies ◽  
The Brain ◽  
Late Palaeolithic

The brain consumes about 20 per cent of the total energy intake in human adults. Primates, and especially humans, have unusually large brains for body size compared with other vertebrates, and fuelling these is a significant drain on both time and energy. Larger-brained primates generally eat fruit-intense diets, but human brains are so large that a reduction in gut size is needed to free up sufficient resources to allow a larger brain to be evolved, placing further pressure on foraging. The early invention of cooking increased nutrient absorption by around 30 per cent over raw food. Increasing digestibility in this way perhaps inevitably leads to risk of obesity when food is super-abundant, as it is in post-industrial societies. However, obesity has clearly been around for a long time, as suggested by the late Palaeolithic Venus figures of Europe, so it is not a novel problem.

Community Replacement Pathways: What Do Fossil Sequences Reveal About Marine Ecosystem Transitions?

1990 ◽  
Vol 5 ◽  
pp. 262-272
Author(s):  
William Miller
Keyword(s):  
Fossil Record ◽  
Large Scale ◽  
Marine Ecosystem ◽  
Small Scale ◽  
Data Sets ◽  
Mass Extinctions ◽  
Ultimate Cause ◽  
Long Time ◽  
History Of ◽  
Time And Energy

Paleontologists have lavished much time and energy on description and explanation of large-scale patterns in the fossil record (e.g., mass extinctions, histories of monophyletic taxa, deployment of major biogeographic units), while paying comparatively little attention to biologic patterns preserved only in local stratigraphic sequences. Interpretation of the large-scale patterns will always be seen as the chief justification for the science of paleontology, but solving problems framed by long time spans and large areas is rife with tenuous inference and patterns are prone to varied interpretation by different investigators using virtually the same data sets (as in the controversy over ultimate cause of the terminal Cretaceous extinctions). In other words, the large-scale patterns in the history of life are the true philosophical property of paleontology, but there will always be serious problems in attempting to resolve processes that transpired over millions to hundreds-of-millions of years and encompassed vast areas of seafloor or landscape. By contrast, less spectacular and more commonplace changes in local habitats (often related to larger-scale events and cycles) and attendant biologic responses are closer to our direct experience of the living world and should be easier to interpret unequivocally. These small-scale responses are reflected in the fossil record at the scale of local outcrops.

Beliefs and Attributes

Philosophy ◽  
1961 ◽  
Vol 36 (137) ◽  
pp. 196-210 ◽  
Author(s):  
Gershon Weiler
Keyword(s):  
Logical Grammar ◽  
Philosophical Paper ◽  
Long Time ◽  
The Difference ◽  
Time And Energy

In a philosophical paper the point one wishes to make should be stated at the very outset. And in dealing with a problem which is as controversial as religion, the bias should be confessed before any points are made. I want to conform at once to both these requirements. I want to discuss beliefs, ordinary beliefs but mainly religious ones, for the expression of which, oddly enough, we use the same word. “Belief” and “Faith” are admittedly different in English, but many languages possess only one word for these and further I shall try to show that even in English the difference is not very great and that they have, if not the same, at least a very similar logical grammar. The point of my argument is that beliefs can be discussed rationally and that they should be so discussed. Religious arguments have been going on for a very long time, and I find it incredible that people of immense intellectual qualities, who devoted their time and energy to these discussions, have been working under a simple delusion, not understanding the very nature of the thing they were doing.

scholarly journals Penerapan Algoritma Horspool pada Aplikasi Katalog Buku Perpustakaan

2019 ◽  
Vol 1 ◽  
pp. 881
Author(s):  
Fince Tinus Waruwu ◽  
Rivalri Kristianto Hondro
Keyword(s):  
Reference Material ◽  
General Public ◽  
Search Algorithm ◽  
String Matching ◽  
Search Algorithms ◽  
Library Services ◽  
Search Process ◽  
Library Book ◽  
Long Time ◽  
Time And Energy

The library is a place that provides various types of reading books as reference material for students, students, educators and the general public. The library certainly provides various types of books that are different according to their needs. Finding books that are needed in a library with a large number of books certainly takes a long time and energy. In supporting library services and providing convenience for visitors, an application is built that helps visitors find the books they need to not need a long time and effort. In the book catalog application it is necessary to apply a search algorithm (string matching). Search algorithms help enders in finding the books they need. The search algorithm applied to the library book catalog application is the Horspool algorithm. Horspool algorithm is one algorithm that is widely used in the search process. By applying the Horspool algorithm in the library book catalog application can be faster and facilitate the process of finding the title of the book.

scholarly journals A Study Showing Research Has Been Valued over Teaching in Higher Education

2015 ◽  
pp. 15-32 ◽  
Author(s):  
Chi Yuan Chen
Keyword(s):  
Higher Education ◽  
Quantitative Research ◽  
Working Hours ◽  
Reward System ◽  
Ministry Of Education ◽  
Different Types ◽  
Long Time ◽  
The Government ◽  
Time And Energy ◽  
Vocational Studies

Research has been valued and given priority over teaching for a long time in academia.  In recent decades, the Taiwanese Ministry of Education has pursued objective and quantitative research criteria and has encouraged higher education institutions to ask teachers to publish papers in SSCI or SCI journals as part of the criteria for promotion and evaluation.  This policy strengthens the concept that research has priority over teaching because teachers must devote more time to research than to teaching in order to be promoted and evaluated.The purpose of this study is to explore the influences that cause teachers to value research over teaching.  To achieve this purpose, document analysis, the analysis of Taiwan Higher Education database and interviews were adapted as methods. First of all, our researchers collected and analyzed the documents for promotion and evaluation of twelve different universities whose areas of specialty included general studies, education, medicine, vocational studies, and the arts. Then, the study used and analyzed the empirical data of teachers’ working hours every week for different tasks from the Taiwan Higher Education Database which investigated the working conditions of teachers in higher education in 2004. Additionally, twenty professors who have different areas of study and work in different types of universities were interviewed to collect teachers’ opinions of the task priority of research, teaching, and service duties. The results showed that academia in Taiwan exhibits the phenomenon that research is valued over teaching. The reasons are due to the requirements of the reward system. The reward system emphasizes research over teaching and service. Teachers’ research achievements are judged based on publishing articles in different types of journals and the amount of research funding they can obtain. The results also showed that every week teachers spend the most time on teaching, then on research, and finally on service. However, teachers emphasize research as the most important task, then teaching, and finally service. Although the majority of teachers think research is the most important duty, there is still twenty percent of teachers who think it is the least important. Although teaching has been thought of as the second most important duty after research, it is the task that the most teachers give as the first priority as far as time spent and none of the interviewees thought it is the least important. Universities and teachers all try to use their professionalism as capital to gain financial support from the government. This situation forces teachers to try to put more time and energy into research, but they still need to maintain teaching and service work quality. Some teachers focus more time and energy on research and ignore the needs of students. Working time endlessly increases even for teachers who out value on both teaching and research. Some suggestions based on the findings have been proposed for Taiwanese higher institutions.

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