scholarly journals Low cost satellite constellations for nearly continuous global coverage

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Lake A. Singh ◽  
William R. Whittecar ◽  
Marc D. DiPrinzio ◽  
Jonathan D. Herman ◽  
Matthew P. Ferringer ◽  
...  
Keyword(s):  
Global Economy ◽  
Low Cost ◽  
Solar Radiation Pressure ◽  
Launch Vehicles ◽  
Satellite Constellations ◽  
Design Life ◽  
Orbital Perturbation ◽  
Global Coverage ◽  
Typical Satellite ◽  
Nearly Continuous

AbstractSatellite services are fundamental to the global economy, and their design reflects a tradeoff between coverage and cost. Here, we report the discovery of two alternative 4-satellite constellations with 24- and 48-hour periods, both of which attain nearly continuous global coverage. The 4-satellite constellations harness energy from nonlinear orbital perturbation forces (e.g., Earth’s geopotential, gravitational effects of the sun and moon, and solar radiation pressure) to reduce their propellant and maintenance costs. Our findings demonstrate that small sacrifices in global coverage at user-specified longitudes allow operationally viable constellations with significantly reduced mass-to-orbit costs and increased design life. The 24-hour period constellation reduces the overall required vehicle mass budget for propellant by approximately 60% compared to a geostationary Earth orbit constellation with similar coverage over typical satellite lifetimes. Mass savings of this magnitude permit the use of less expensive launch vehicles, installation of additional instruments, and substantially improved mission life.

scholarly journals Reinforcement of Recycled Aggregate by Microbial-Induced Mineralization and Deposition of Calcium Carbonate—Influencing Factors, Mechanism and Effect of Reinforcement

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 887
Author(s):  
Chunhua Feng ◽  
Buwen Cui ◽  
Haidong Ge ◽  
Yihong Huang ◽  
Wenyan Zhang ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Global Economy ◽  
Low Cost ◽  
High Water ◽  
Strengthening Mechanism ◽  
Recycled Aggregate ◽  
Strengthening Effect ◽  
Calcium Carbonate Precipitation ◽  
Environmental Friendliness ◽  
Advantages And Disadvantages

Recycled aggregate is aggregate prepared from construction waste. With the development of a global economy and people’s attention to sustainable development, recycled aggregate has shown advantages in replacing natural aggregate in the production of concrete due to its environmental friendliness, low energy consumption, and low cost. Recycled aggregate exhibits high water absorption and a multi-interface transition zone, which limits its application scope. Researchers have used various methods to improve the properties of recycled aggregate, such as microbially induced calcium carbonate precipitation (MICP) technology. In this paper, the results of recent studies on the reinforcement of recycled aggregate by MICP technology are synthesized, and the factors affecting the strengthening effect of recycled aggregate are reviewed. Moreover, the strengthening mechanism, advantages and disadvantages of MICP technology are summarized. After the modified treatment, the aggregate performance is significantly improved. Regardless of whether the aggregate was used in mortar or concrete, the mechanical properties of the specimens were clearly improved. However, there are some issues regarding the application of MICP technology, such as the use of an expensive culture medium, a long modification cycle, and untargeted mineralization deposition. These difficulties need to be overcome in the future for the industrialization of regenerated aggregate materials via MICP technology.

Low cost liquid upper stage for small launch vehicles

1994 ◽  
Author(s):  
Daniel Moser ◽  
Scott Frazier
Keyword(s):  
Low Cost ◽  
Launch Vehicles ◽  
Upper Stage

INVITED POLICY ECONOMICS PAPER — ECONOMICS IN ASIA 1995–2020

2021 ◽  
pp. 1-15
Author(s):  
JOERGEN OERSTROEM MOELLER
Keyword(s):  
Market Economy ◽  
Value Chain ◽  
Global Economy ◽  
Consumer Preferences ◽  
Low Cost ◽  
Second Phase ◽  
Public And Private ◽  
The Us ◽  
Anglo American ◽  
Asian Economy

Over the last 25 years, Asia’s economic rise has been extraordinary. Its share of global gross domestic product (GDP) has risen from 5.8% to 22.9%. 1 The first phase of high economic growth — up to 1995 — saw Asia enter the global supply chain primarily with labor-intensive/low-cost manufacturing. Domestic consumption was a fairly low share of GDP; Asia was manufacturing mainly for consumption in the US and Europe. As such, it was primarily a rule-taker. In the second phase — from 1995 to 2020 — it gradually turned into an economic force joining the US and Europe in shaping the global economy, exercising significant influence upon the value chain, the cycles of the global economy, transport and logistics, the global capital markets and consumption patterns (consumer preferences and tastes). While not yet among the leading rule-makers, it had become difficult for policymakers (public and private) to make decisions without Asia’s consent. To form an opinion of today’s emerging third phase — post 2020 — the intriguing question is whether the Asian countries have adopted what may be termed Anglo-American economic thinking (basically, the primacy of the market). Or whether behind the curtain, the Asian economy works in its own way diverging from the American and British economic schools. Since demographics and sheer economic scale mean that Asia will dominate the global economy in the years to come, the nature of the Asian economy will be of crucial importance for the future global economy. The conclusion of this paper is that “Asia” in many respects differs — and fundamentally so — from market economy principles. How this prospect should be interpreted is also evolving, as circumstances change. Certainly, the repercussions of COVID-19 have not been the same in the US, Europe, East Asia and South Asia — and this may suggest that socio-political structures have a stronger impact on economic outcomes than economic theory teaches, thus calling into question the global validity of market economy principles.

scholarly journals Accuracy of the TanDEM-X Digital Elevation Model for Coastal Geomorphological Studies in Patagonia (South Argentina)

2019 ◽  
Vol 11 (15) ◽  
pp. 1767 ◽  
Author(s):  
Francesca Pasquetti ◽  
Monica Bini ◽  
Andrea Ciampalini
Keyword(s):  
Digital Elevation Model ◽  
Spatial Resolution ◽  
Mean Squared Error ◽  
Low Cost ◽  
High Agreement ◽  
Squared Error ◽  
Digital Elevation ◽  
Vertical Error ◽  
Global Coverage ◽  
Elevation Model

The aim of this paper is to evaluate the usefulness of TanDEM-X DEM (digital elevation model) for remote geomorphological analysis in Argentinian Patagonia. The use of a DEM with appropriate resolution and coverage might be very helpful and advantageous in vast and hardly accessible areas. TanDEM-X DEM could represent an unprecedented opportunity to identify geomorphological features because of its global coverage, ~12 m spatial resolution and low cost. In this regard, we assessed the vertical accuracy of TanDEM-X DEM through comparison with Differential Global Positioning System (DGPS) datasets collected in two areas of the Patagonia Region during a field survey; we then investigated different types of landforms by creating the elevation profiles. The comparison indicates a high agreement between TanDEM-X DEM and reference values, with a mean absolute vertical error (MAE) of 0.53 m, and a root mean squared error (RMSE) of 0.73 m. The results of landform analysis show an appropriate spatial resolution to detect different features such as beach ridges, which are impossible to delineate with other lower resolution DEMs. For these reasons, TanDEM-X DEM constitutes a useful tool for detailed geomorphological analyses in Argentinian Patagonia.

Implementation of Environmental Friendly Multi Regional Packaging and Logistics Solutions for Semi-Finished Goods

2006 ◽  
Author(s):  
Jaime Villafuerte
Keyword(s):  
Global Economy ◽  
Low Cost ◽  
Packaging Materials ◽  
Business Practices ◽  
Manufacturing Companies ◽  
Consumer Market ◽  
Final Assembly ◽  
Environmental Friendly ◽  
Long Run ◽  
Geographic Regions

In order to take advantage of the global economy, manufacturing companies have developed a complex and an extended supply chain which includes manufacturing components or parts in LCCs (low-cost countries) and shipping them to factories near to their consumer market for final assembly, customization and distribution. These activities involve several different organizations that follow widely different approaches in logistical management. In order to sustain the long shipment distances in different geographic regions, (i.e. China-Mexico-US-Europe), handling & environmental conditions & shipping modes (Air vs Ground vs Sea); suitable, flexible and economical packaging solutions are required. This flow of semi-finished goods usually requires packaging materials such as carriers (i.e. wooden pallets) and moisture inhibitors (i.e. desiccants) to protect the goods. Competitive pressures, environmental consciousness, customer awareness and legislative requirements have driven manufacturers to review business practices and redesign solutions that are environmentally friendly, as well as help reduce costs in the long run. The author of this paper will present an experience where "non-traditional" packaging is used as an economical and environmental friendly solution to globally transport goods between multiple facilities.

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