1,487 research outputs found
Engineering calculations for the Delta S method of solving the orbital allotment problem
The method of calculating single-entry separation requirements for pairs of satellites is extended to include the interference on the top link as well as on the down link. Several heuristic models for analyzing the effects of shaped-beam antenna designs on required satellite separations are introduced and demonstrated with gain contour plots. The calculation of aggregate interference is extended to include the effects of up-link interference. The relationship between the single-entry C/I requirements, used in determining satellite separation constraints for various optimization procedures, and the aggregate C/I values of the resulting solutions is discussed
Kajian Faktor Sosial Ekonomi terhadap Respon Petani dalam Menerapkan Inovasi Double Track untuk Meningkatkan Ketahanan Pangan Petani pada Masa Pandemi Covid-19
Penelitian ini telah dilaksanakan pada akhir tahun 2022, bertujuan mengetahui factor social ekonomi berkorelasi dengan respon petani dalam penerapan inovasi Double Track pada tanaman jagung. Sebanyak 83 petani dipilih secara acak. Pengumpulan data menggunakan metode survei. Data dianalisis dengan menggunakan korelasi Rank Spearman dengan sistem komputasi SPPS 26. Hasilnya adalah faktor berkorelasi nyata dengan respon petani adalah pendidikan formal, pendidikan nonformal, dan luas lahan.. Dibutuhkan perhatian pemerintah untuk peningkatan kegiatan penyuluhan dan pendampingan dengan metode gabungan yang terdiri dari ceramah, diskusi, pelatihan partisipatif, SLP dan konsultasi pribadi tentang sistem âdouble trackâ.Sebaliknya, faktor umur, pengalaman berusahatani dan jumlah tanggungan keluarga tidak memiliki korelasi dengan respon petani
Efficient Data Collection and Event Boundary Detection in Wireless Sensor Networks Using Tiny Models
Design and Implementation of a State-Driven Operating System for Highly Reconfigurable Sensor Networks
Due to the low-cost and low-power requirement in an individual sensor node, the available computing resources turn out to be very limited like small memory footprint and irreplaceable battery power. Sensed data fusion might be needed before being transmitted as a tradeoff between procession and transmission in consideration of saving power consumption. Even worse, the application program needs to be complicated enough to be self-organizing and dynamically reconfigurable because changes in an operating environment continue even after deployment. State-driven operating system platform offers numerous benefits in this challenging situation. It provides a powerful way to accommodate complex reactive systems like diverse wireless sensor network applications. The memory usage can be bounded within a state transition table. The complicated issues like concurrency control and asynchronous event handling capabilities can be easily achieved in a well-defined behavior of state transition diagram. In this paper, we present an efficient and effective design of the state-driven operating system for wireless sensor nodes. We describe that the new platform can operate in an extremely resource constrained situation while providing the desired concurrency, reactivity, and reconfigurability. We also compare the executing results after comparing some benchmark test results with those on TinyOS
Population control of 2s-2p transitions in hydrogen
We consider the time evolution of the occupation probabilities for the 2s-2p
transition in a hydrogen atom interacting with an external field, V(t). A
two-state model and a dipole approximation are used. In the case of degenerate
energy levels an analytical solution of the time-dependent Shroedinger equation
for the probability amplitudes exists. The form of the solution allows one to
choose the ratio of the field amplitude to its frequency that leads to temporal
trapping of electrons in specific states. The analytic solution is valid when
the separation of the energy levels is small compared to the energy of the
interacting radiation.Comment: 6 pages, 3 figure
An empirical comparison of three methods for multiple cut-off diagnostic test meta-analysis of the Patient Health Questionnaire-9 (PHQ-9) depression screening tool using published data versus individual level data
Evaluation of Externality Costs in Life-Cycle Optimization of Municipal Solid Waste Management Systems
The
development of sustainable solid waste management (SWM) systems
requires consideration of both economic and environmental impacts.
Societal life-cycle costing (S-LCC) provides a quantitative framework
to estimate both economic and environmental impacts, by including
âbudget costsâ and âexternality costsâ.
Budget costs include market goods and services (economic impact),
whereas externality costs include effects outside the economic system
(e.g., environmental impact). This study demonstrates the applicability
of S-LCC to SWM life-cycle optimization through a case study based
on an average suburban U.S. county of 500âŻ000 people generating
320âŻ000 Mg of waste annually. Estimated externality costs are
based on emissions of CO<sub>2</sub>, CH<sub>4</sub>, N<sub>2</sub>O, PM<sub>2.5</sub>, PM<sub>10</sub>, NO<sub><i>x</i></sub>, SO<sub>2</sub>, VOC, CO, NH<sub>3</sub>, Hg, Pb, Cd, Cr (VI), Ni,
As, and dioxins. The results indicate that incorporating S-LCC into
optimized SWM strategy development encourages the use of a mixed waste
material recovery facility with residues going to incineration, and
separated organics to anaerobic digestion. Results are sensitive to
waste composition, energy mix and recycling rates. Most of the externality
costs stem from SO<sub>2</sub>, NO<sub><i>x</i></sub>, PM<sub>2.5</sub>, CH<sub>4</sub>, fossil CO<sub>2</sub>, and NH<sub>3</sub> emissions. S-LCC proved to be a valuable tool for policy analysis,
but additional data on key externality costs such as organic compounds
emissions to water would improve future analyses
Evaluation of land surface models in reproducing satellite-derived LAI over the high-latitude northern hemisphere. Part I: Uncoupled DGVMs
PublishedJournal ArticleLeaf Area Index (LAI) represents the total surface area of leaves above a unit area of ground and is a key variable in any vegetation model, as well as in climate models. New high resolution LAI satellite data is now available covering a period of several decades. This provides a unique opportunity to validate LAI estimates from multiple vegetation models. The objective of this paper is to compare new, satellite-derived LAI measurements with modeled output for the Northern Hemisphere. We compare monthly LAI output from eight land surface models from the TRENDY compendium with satellite data from an Artificial Neural Network (ANN) from the latest version (third generation) of GIMMS AVHRR NDVI data over the period 1986-2005. Our results show that all the models overestimate the mean LAI, particularly over the boreal forest. We also find that seven out of the eight models overestimate the length of the active vegetation-growing season, mostly due to a late dormancy as a result of a late summer phenology. Finally, we find that the models report a much larger positive trend in LAI over this period than the satellite observations suggest, which translates into a higher trend in the growing season length. These results highlight the need to incorporate a larger number of more accurate plant functional types in all models and, in particular, to improve the phenology of deciduous trees. © 2013 by the authors.The corresponding author also thanks the CONACYT-CECTI and the University of Exeter for their funding during the PhD studies. The National Center for Atmospheric Research is sponsored by the National Science Foundation
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Quantitative or momentum-based multi-style rotation? UK experience
The objective of this article is to examine whether short-term variation in the ranking of size and style index returns in the UK equity market is better predictable and exploitable by means of quantitative or momentum style-rotation strategies. Using UK index data, we assess the profitability of a number of long-only and long/short multi-stylerotation strategies based on these two alternative methods. The findings suggest that trading rules based on simple short-term momentum strategies are able to generate higher Sharpe ratios and greater end-of-period wealth at a reasonable level of transaction costs than our quantitatively based trading rules. This result is particularly pronounced among the long-only strategies
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