به نام خدا
Title: The role of the atmosphere in the provision of ecosystem services
Authors: Ellen J. Cooter, Anne Rea, Randy Bruins, Donna Schwede, Robin Dennis
Abstract: Solving the environmental problems that we are facing today requires holistic approaches to analysis and decision making that include social and economic aspects. The concept of ecosystem services, defined as the benefits people obtain from ecosystems, is one potential tool to perform such assessments. The objective of this paper is to demonstrate the need for an integrated approach that explicitly includes the contribution of atmospheric processes and functions to the quantification of air–ecosystem services. First, final and intermediate air–ecosystem services are defined. Next, an ecological production function for clean and clear air is described, and its numerical counterpart (the Community Multiscale Air Quality model) is introduced. An illustrative numerical example is developed that simulates potential changes in air–ecosystem services associated with the conversion of evergreen forest land in Mississippi, Alabama and Georgia to commercial crop land. This one-atmosphere approach captures a broad range of service increases and decreases. Results for the forest to cropland conversion scenario suggest that although such change could lead to increased biomass (food) production services, there could also be coincident, seasonally variable decreases in clean and clear air–ecosystem services (i.e., increased levels of ozone and particulate matter) associated with increased fertilizer application. Metrics that support the quantification of these regional air–ecosystem changes require regional ecosystem production functions that fully integrate biotic as well as abiotic components of terrestrial ecosystems, and do so on finer temporal scales than are used for the assessment of most ecosystem services.
Publish Year: 2013
Published in: Science of The Total Environment - Science Direct
Number of Pages: 12
موضوع: حفاظت از محیط زیست
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Structure learning for belief rule base expert system: A comparative study
Authors: Leilei Chang, Yu Zhou, Jiang Jiang, Mengjun Li, Xiaohang Zhang
Abstract: The Belief Rule Base (BRB) is an expert system which can handle both qualitative and quantitative information. One of the applications of the BRB is the Rule-base Inference Methodology using the Evidential Reasoning approach (RIMER). Using the BRB, RIMER can handle different types of information under uncertainty. However, there is a combinatorial explosion problem when there are too many attributes and/or too many alternatives for each attribute in the BRB. Most current approaches are designed to reduce the number of the alternatives for each attribute, where the rules are derived from physical systems and redundant in numbers. However, these approaches are not applicable when the rules are given by experts and the BRB should not be oversized. A structure learning approach is proposed using Grey Target (GT), Multidimensional Scaling (MDS), Isomap and Principle Component Analysis (PCA) respectively, named as GT–RIMER, MDS–RIMER, Isomap–RIMER and PCA–RIMER. A case is studied to evaluate the overall capability of an Armored System of Systems. The efficiency of the proposed approach is validated by the case study results: the BRB is downsized using any of the four techniques, and PCA–RIMER has shown excellent performance. Furthermore, the robustness of PCA–RIMER is further verified under different conditions with varied number of attributes.
Publish Year: 2013
Published in: Knowledge-Based Systems - Science Direct
Number of Pages: 14
موضوع: سیستمهای خبره
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Information Fusion and Discounting Techniques for Decision Support in Aerospace
Authors: Fiona Browne , Yan Jin , Niall Rooney Hui Wang
Abstract: Decision makers are required to make critical decisions throughout all stages of a life-cycle in large-scale projects. These decisions are important as they impact upon the outcome and the success of projects. In this paper we present an evidential reasoning framework to aid decision-makers in the decision - making process. This approach utilizes the Dezert-Smarandache Theory (DSm) to fuse heterogeneous evidence sources that suffer from levels of uncertainty, imprecision and conflicts to provide beliefs for decision options. To analyze the impact that source reliability and priority has upon the decision making process a reliability discounting technique along with a priority discounting technique are applied. Application of the evidential reasoning framework is illustrated using a Case Study based in the Aerospace domain.
Publish Year: 2012
Published in: INDIN - IEEE
Number of Pages: 6
موضوع: مهندسی هوافضا، سیستمهای تصمیم یار
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Aero-Optical Effects In Free-Space Laser Communications
Authors: Stanislav Gordeyev, Eric Jumper
Abstract: When a laser beam is transmitted from an airborne platform, it must first pass through a relatively thin region of the turbulent flow in the immediate vicinity of the airplane. Unsteady density variations present in the turbulent flow will imprint spatial/temporal variations on the otherwise planar outgoing wavefronts. These variations in wavefronts will force the beam to move, change its shape and even break into several spots on a distant target. These aero-optical effects [1,2], even in the absence of any atmospheric optical distortions, might significantly degrade a performance of any free-space, laser-based airborne systems at subsonic, transonic or supersonic speeds.
Publish Year: 2012
Published in: PSSTMS - IEEE
Number of Pages: 2
موضوع: فوتونیک، لیزر
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: A Cognitive Link Adaptation Strategy with Differentiated Responses on Wi-Fi System-on-Chip
Authors: Taeyoung Lee, Myounghwan Lee, Jaeeun Kang, Kyungik Cho, ChilYoul Hacky Yang, and Scott Seongwook Lee
Abstract: The dynamic change of wireless channel condition causes poor Wi-Fi quality of service. To cope with the channel variation of wireless communication, the essential strategy for the physical layer with multi-rate capability is the link adaptation. However, because definite guidelines for rate changes do not exist, most link adaptation algorithms can misleadingly increase transmission rates. Therefore, we propose a cognitive link adaptation scheme, sensing link adaptation urgency and responding with differentiated rate control such as the long-term rate adaptation with a short-term rate drop. To evaluate the proposed scheme, we implement the link adaptation scheme on Wi-Fi System-on-Chip, applying the optimal HW/SW partitioning technique to reduce the SW processing delay from heavy operating calculation for the algorithm. The experiment shows that the proposed algorithm increases the packet arrival rate in a real Wi-Fi environment by reducing transmission failure due to wrong rate changes.
Publish Year: 2013
Published in: CCNC - IEEE
Number of Pages: 6
موضوع: شبکه های بی سیم
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
