Crocodylus johnstoni in the McKinlay Area, N.T. VIII. A Population Simulation Model

1985 ◽  
Vol 12 (3) ◽  
pp. 541 ◽  
Author(s):  
AMA Smith ◽  
GJW Webb
Keyword(s):  
Simulation Model ◽  
Population Increase ◽  
Natural Rate ◽  
River Population ◽  
Return Rates ◽  
Crocodylus Johnstoni ◽  
Research Activities ◽  
Sensitivity Tests ◽  
Estimated Error ◽  
Population Simulation

A population simulation model was constructed for the McKinlay River population of the freshwater crocodile Crocodylus johnstoni. C, johnstoni are long-lived reptiles (50 y +) which take 9-16 years to reach maturity. As a consequence, the effects of legal hunting before 1963 are still reflected in an unstable population age structure. No quantitative data on the original population densities exist, nor are there data on the densities at which equilibrium can be expected in the future. The model examines the dynamics of a population which is still expanding and does not take into account density-dependent factors which may ultimately limit the population. If the population was undisturbed for 10 years, the model predicted the mean natural rate of population increase would be 1 .5% per annum. However, the population has been disturbed during research activities, and when these disturbances and manipulations were simulated the model predicted a 4% decrease in the population between 1979 and 1983. Independent surveys in both 1979 and 1983 indicated a 5% decrease in the population. This consistency has been interpreted as indicating that the model's predictions are not grossly erroneous. Sensitivity tests were carried out in which most parameters in the model were independently varied by plus or minus their estimated error, while other parameters were held constant. The resultant changes in the estimated population size after 10 years indicated the model was most sensitive to the age-specific mortality estimates. C. johnstoni management has the conservation requirement of maintaining or even enhancing the density of wild populations. Sustained-yield harvesting can theoretically be achieved without compromising this requirement by harvesting eggs and/or hatchlings, and later returning a proportion of the harvest to the population when they are larger and have a greater probability of surviving. When released into the wild, captive-raised C. johnstoni survive as well as wild ones of equivalent sizes. The model was used to simulate egg and hatchling harvests with different collection and return rates, and different ages of returned animals. It was also used to simulate harvests of post-hatchling crocodiles, without a return of captiveraised animals.

Advanced Solutions for Healthcare Facility Management

2014 ◽  
Vol 2 (2) ◽  
pp. 41-56
Author(s):  
Francesco Longo ◽  
Letizia Nicoletti ◽  
Alessandro Chiurco ◽  
Antonio Calogero
Keyword(s):  
Simulation Model ◽  
Value Chain ◽  
Model Development ◽  
Research Work ◽  
Healthcare Facility ◽  
Facility Management ◽  
Lean Management ◽  
Management Tools ◽  
Research Activities ◽  
Starting Point

This paper presents a simulation study carried out within a private healthcare facility with the aim of understanding whether or not it is able to handle a greater flow of incoming patients as well as the related impact on the overall efficiency. As a result, the simulation outcomes have pointed out the need for an internal work re-organization that has been devised through Lean Management tools and methodologies. The simulation model has, then, been used to predict the intended changes effects as well as their feasibility. Particular attention has been paid on the care administration process, provided that research activities are still ongoing to investigate other processes in the patient value chain where there is still substantial room for improvement. The proposed research work is grounded on an in dept analysis of the main processes and activities taking place in the healthcare facility as a starting point for the simulation model development. Afterwards, simulation has been used for “as-is” analyses and, in combination with Lean Management approaches, for “what-if” studies whose results and findings are discussed.

scholarly journals Population Simulation Model ofSitophilus zeamais(Coleoptera: Curculionidae) in Grain Stores in West Africa

1999 ◽  
Vol 28 (5) ◽  
pp. 836-844 ◽  
Author(s):  
William G. Meikle ◽  
Niels Holst ◽  
Richard H. Markham
Keyword(s):  
West Africa ◽  
Simulation Model ◽  
Grain Stores ◽  
Population Simulation

scholarly journals Study of the Influence of Winding and Sensor Design on Ultra-High Frequency Partial Discharge Signals in Power Transformers

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5113 ◽  
Author(s):  
Chandra Prakash Beura ◽  
Michael Beltle ◽  
Stefan Tenbohlen
Keyword(s):  
Simulation Model ◽  
High Frequency ◽  
Partial Discharge ◽  
Complex Structure ◽  
Signal Propagation ◽  
Power Transformers ◽  
Sensor Design ◽  
Propagation Characteristics ◽  
Ultra High Frequency ◽  
Research Activities

Ultra-high frequency (UHF) partial discharge (PD) measurements in power transformers are becoming popular because of the advantages of the method. Therefore, it is necessary to improve the basic understanding of the propagation of signals inside the transformer tank and the factors that influence the sensitivity of the measurement. Since the winding represents a major obstacle to the propagation of the UHF signals, it is necessary to study the effect of winding design on signal propagation. Previous research activities have studied these effects using simplified models, and it is essential to consider the complexity of propagation in a complete transformer tank. Additionally, the quality of UHF PD measurements depends, to a large extent, on the sensitivity of the UHF sensors. In this contribution, a simulation model consisting of a simple, grounded enclosure with multiple winding designs is used to study the propagation characteristics of UHF signals when an artificial PD source is placed inside the winding. After analysis of the results, the winding designs are incorporated in an existing and validated simulation model of a 420 kV power transformer and analyzed to observe the influence in a more complex structure. Two commonly used sensor designs are also used in the simulation model to receive the signals. In all cases, the propagation and signal characteristics are analyzed and compared to determine the influence of the winding and sensor design on the UHF signals. It is found that the level of detail of winding design has a significant impact on the propagation characteristics. However, the attenuation characteristics of the UHF signals received by the two sensor designs are similar, with the electric field distribution around the sensor being the key difference.

scholarly journals Comparing the Lifestyle Interventions for Prediabetes: An Integrated Microsimulation and Population Simulation Model

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Amin Khademi ◽  
Lu Shi ◽  
Amir Ali Nasrollahzadeh ◽  
Hariharaprabhu Narayanan ◽  
Liwei Chen
Keyword(s):  
Simulation Model ◽  
Lifestyle Interventions ◽  
Population Simulation

scholarly journals A theoretical model for the prevention of Banana Moko (Musa AAB Simmonds)

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 1443
Author(s):  
Marly Grajales Amorocho ◽  
Anibal Muñoz Loaiza
Keyword(s):  
Theoretical Model ◽  
Differential Equations ◽  
Simulation Model ◽  
Ordinary Differential Equations ◽  
Logistic Growth ◽  
Maximum Capacity ◽  
Linear Ordinary Differential Equations ◽  
Variable Population ◽  
Population Simulation ◽  
Over Time

A population simulation model with non-linear ordinary differential equations is presented, which interprets the dynamics of the banana Moko, with prevention of the disease and population of susceptible and infected plants over time. A crop with a variable population of plants and a logistic growth of replanting is assumed, taking into account the maximum capacity of plants in the delimited study area.

Further Analysis of Population Trends in the Northwest Atlantic Harp Seal (Phoca groenlandica) from 1967 to 1985

1986 ◽  
Vol 43 (3) ◽  
pp. 553-564 ◽  
Author(s):  
Derek Roff ◽  
W. Don Bowen
Keyword(s):  
Simulation Model ◽  
Age Structure ◽  
Population Trends ◽  
Harp Seal ◽  
Population Increase ◽  
Northwest Atlantic ◽  
Phoca Groenlandica ◽  
Precise Estimation ◽  
Rate Of Increase ◽  
Minimum Estimate

We examined changes in the age structure of the northwest Atlantic harp seal (Phoca groenlandica) population from 1967 to 1983. Through this period there has been a statistically significant population increase in the proportion of seals aged 2–6 yr. Precise estimation of the rate of increase is hindered by a tendency for immature seals to be overrepresented in samples of molting males. Two methods were developed to correct for this bias; these provide a minimum estimate of the proportion of seals aged 2–6 yr present in 1967. Utilizing a simulation model, we showed that the unadjusted and adjusted age distributions are both extremes and that the correct distribution probably lies between them. In both cases the data are more consistent with an increasing than a decreasing population, given the level of catch experienced by this population up to 1982. Recent total catches of 75 000 or less in 1983 and 1984 are substantially below the most conservative estimates of replacement yield in 1985 and will result in a further, more rapid population increase.

Development of a hemp (Cannabis sativa L.) simulation model 4. Model description and validation

2000 ◽  
Vol 40 (3) ◽  
pp. 425 ◽  
Author(s):  
S. N. Lisson ◽  
N. J. Mendham ◽  
P. S. Carberry
Keyword(s):  
Simulation Model ◽  
Leaf Area ◽  
Biomass Production ◽  
Growth And Development ◽  
Field Trials ◽  
Model Description ◽  
Agricultural System ◽  
Independent Dataset ◽  
Systems Model ◽  
Research Activities

In studies assessing the prospects for a hemp industry, as well as in longer term research activities, the use of a hemp simulation model to complement the more traditional agronomic field trials would offer a number of potential advantages. In addition to being cost and labour intensive, field trials with hemp have political, social and security implications. With these implications in mind, a simulation model that captures the growth and development processes of hemp in response to management, genotypic, soil and climate factors, has the potential to increase research efficiency. The model could be used to assess the need, extent and nature of field trials, to help interpret field trial results, and to investigate temporal and spatial variability in selected crop responses. This paper describes a hemp crop growth and development model (APSIM-Hemp) and its validation against an independent dataset. The model was developed as a crop module within the framework of the larger systems model, Agricultural Production Systems sIMulator (APSIM), to extend the capability to encompass the agricultural system in which hemp is grown. APSIM-Hemp incorporates relationships developed in the previous papers in this series relating to pre- and post-emergent phenology and leaf area production. Other parameters relating to biomass partitioning, biomass production, water uptake and nitrogen uptake were derived from separate field studies and selected references. APSIM-Hemp adequately predicted phenology, leaf area and biomass production for the cultivar Kompolti at Forthside in north-western Tasmania, for a dataset comprised of results from trials conducted over 3 seasons and including treatments of sowing date, irrigation regime and plant density. Although performing well against this independent dataset, the performance of the model needs to be further validated over a range of other soil, climate and management conditions in order to assess its broader predictive capability. Notwithstanding these limitations, the sound basis of a model for simulating the growth and development of hemp has been developed.

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