Restoration of bighorn sheep metapopulations in and near 15 national parks: Conservation of a severely fragmented species; Volume I, Planning, problem definition, findings, and restoration

1999 ◽  
Author(s):  
Francis J. Singer ◽  
Michelle A. Gudorf
Keyword(s):  
National Parks ◽  
Bighorn Sheep ◽  
Problem Definition ◽  
Planning Problem

Restoration of Bighorn Sheep Metapopulations in and Near Western National Parks

2000 ◽  
Vol 8 (4S) ◽  
pp. 14-24 ◽  
Author(s):  
Francis J. Singer ◽  
Vernon C. Bleich ◽  
Michelle A. Gudorf
Keyword(s):  
National Parks ◽  
Bighorn Sheep

Conflicts in national parks: A case study of helicopters and bighorn sheep time budgets at the grand canyon

1991 ◽  
Vol 56 (3) ◽  
pp. 317-328 ◽  
Author(s):  
Craig A. Stockwell ◽  
Gary C. Bateman ◽  
Joel Berger
Keyword(s):  
National Parks ◽  
Grand Canyon ◽  
Bighorn Sheep ◽  
Time Budgets

Optimize landscape fuel treatment locations to create control opportunities for future fires

2012 ◽  
Vol 42 (6) ◽  
pp. 1002-1014 ◽  
Author(s):  
Yu Wei
Keyword(s):  
National Parks ◽  
Spatial Information ◽  
Programming Model ◽  
Mixed Integer ◽  
Fire Intensity ◽  
Planning Problem ◽  
Fire Control ◽  
Fuel Treatments ◽  
Fuel Treatment ◽  
Ignition Probability

Fuel treatment can improve the efficiency of controlling future catastrophic fires. Selecting optimal fuel treatment locations across a landscape is a challenging strategic planning problem in wildland fire management. This research develops a new fuel treatment optimization model by extending a fire suppression model to simultaneously consider many future fires. Fire is ignited from every grid cell in a landscape and modeled for various durations in a mixed integer programming model. Fuel treatment in a cell decreases its fire intensity and makes future fire control effective in it. This model allocates fuel treatments to minimize the total landscape future fire loss. It was first tested on several artificial landscapes for model validation. Results show that it tends to allocate fuel treatments in contiguous areas following regular and intuitive spatial patterns. Spatial fuel treatment layouts vary according to the change of fire ignition probability distribution, the distribution of value to be protected from fire, and fire duration assumptions. Trade-off between protecting different parts of a landscape is a major driver in designing fuel treatment layouts. A test case in the Sequoia and Kings Canyon national parks demonstrates how this model assembles spatial information and helps study the effects of fuel treatments in a heterogeneous landscape. This model allows managers to assemble information from many possible future fires to make informative strategic-level fuel treatment decisions. A potential model extension and the limitations of this model are also discussed.

Temporal geographic variation in the lambing season of bighorn sheep

1982 ◽  
Vol 60 (8) ◽  
pp. 1781-1793 ◽  
Author(s):  
Richard W. Thompson ◽  
Jack C. Turner
Keyword(s):  
Plant Growth ◽  
Geographic Variation ◽  
Sierra Nevada ◽  
National Parks ◽  
Bighorn Sheep ◽  
Ovis Canadensis ◽  
Vegetative Development ◽  
Growing Seasons ◽  
Environmental Regimes ◽  
Sierra Nevada Mountains

Temporal geographic variation in lambing seasons was statistically assessed for 22 populations, including 5 ecological races, of North American bighorn sheep (Ovis canadensis ssp.) from the Canadian National Parks (52° N) to western Texas (30° N). Throughout their distribution, bighorn lambing occurs coincident with the period of vegetative development when the environmental regime ameliorates neonate survival. Analyses generally demonstrate later and shorter lambing seasons in higher latitudinal populations (P < 0.001). Inception of lambing occurs later with colder temperatures, increased snowfall, at higher latitudes and elevations, and with later and shorter growing seasons [Formula: see text]. Additionally, a significant (P < 0.001) divergence in the reproductive "strategy" (median onset and duration of lambing) exists between bighorn herds of the Sierra Nevada Mountains, California (37° N) and the Desert National Wildlife Range, Nevada (36° N) as a result of two distinct, but adjacent environmental regimes. Lambing in northern populations is cued to a brief, relatively predictable period of plant growth. Southern bighorn protract lambing such that some recruitment coincides with relatively unpredictable plant growth, triggered by erratic rains.

Offline-Channel Planning in Smart Omnichannel Retailing

2021 ◽  
Author(s):  
Jian Chen ◽  
Yong Liang ◽  
Hao Shen ◽  
Zuo-Jun Max Shen ◽  
Mengying Xue
Keyword(s):  
Parameter Estimation ◽  
Real Data ◽  
Problem Definition ◽  
Mixed Integer ◽  
Planning Problem ◽  
Data Sets ◽  
Solution Approach ◽  
Planning Decisions ◽  
Managerial Implications ◽  
Offline Channels

Problem definition: Observing the retail industry inevitably evolving into omnichannel, we study an offline-channel planning problem that helps an omnichannel retailer make store location and location-dependent assortment decisions in its offline channel to maximize profit across both online and offline channels, given that customers’ purchase decisions depend on not only their preferences across products but also, their valuation discrepancies across channels, as well as the hassle costs incurred. Academic/practical relevance: The proposed model and the solution approach extend the literature on retail-channel management, omnichannel assortment planning, and the broader field of smart retailing/cities. Methodology: We derive parameterized models to capture customers’ channel choice and product choice behaviors and customize a corresponding parameter estimation approach employing the expectation-maximization method. To solve the proposed optimization model, we develop a tractable mixed integer second-order conic programming reformulation and explore the structural properties of the reformulation to derive strengthening cuts in closed form. Results: We numerically validate the efficacy of the proposed solution approach and demonstrate the parameter estimation approach. We further draw managerial insights from the numerical studies using real data sets. Managerial implications: We verify that omnichannel retailers should provide location-dependent offline assortments. In addition, our benchmark studies reveal the necessity and significance of jointly determining offline store locations and assortments, as well as of incorporating the online channel while making offline-channel planning decisions.

scholarly journals Operational Considerations regarding On-Demand Air Mobility: A Literature Review and Research Challenges

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Xiaoqian Sun ◽  
Sebastian Wandelt ◽  
Michael Husemann ◽  
Eike Stumpf
Keyword(s):  
Aircraft Design ◽  
Problem Definition ◽  
Operational Planning ◽  
Planning Problem ◽  
Full Potential ◽  
Demand Model ◽  
Transportation Demand ◽  
On Demand ◽  
Formal Problem ◽  
Performance Dimensions

The idea and development of on-demand air mobility (ODAM) services are revolutionizing our urban/regional transportation sector by exploring the third dimension: vertical airspace. The fundamental concept of on-demand air taxi operations is not new, but advances in aircraft design and battery/engine technology plus massive problems with congestion and increased travel demands around the world have recently led to a large number of studies which aim to explore the potential benefits of ODAM. Unfortunately, given the lack of an established, formal problem definition, missing reference nomenclature for ODAM research, and a multitude of publication venues, the research development is not focused and, thus, does not tap the full potential of the workforce engaged in this topic. This study synthesizes the recently published literature on operational aspects of ODAM. Our contribution consists of two major parts. The first part dissects previous studies and performs cross-comparison of report results. We cover five main categories: demand estimation methodology, infrastructure/port design/location problem, operational planning problem, operational constraints’ identification, and competitiveness with other transportation modes. The second part complements the report of aggregated findings by proposing a list of challenges as a future agenda for ODAM research. Most importantly, we see a need for a formal problem definition of ODAM operational planning processes, standard open datasets for comparing multiple performance dimensions, and a universal, multimodal transportation demand model.

Linking Creativity With Problem Definition

1994 ◽  
Vol 39 (7) ◽  
pp. 765-766
Author(s):  
Stanley S. Gryskiewicz
Keyword(s):  
Problem Definition
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