scholarly journals A novel length-based empirical estimation method of spawning potential ratio (SPR), and tests of its performance, for small-scale, data-poor fisheries

2014 ◽  
Vol 72 (1) ◽  
pp. 217-231 ◽  
Author(s):  
Adrian Hordyk ◽  
Kotaro Ono ◽  
Sarah Valencia ◽  
Neil Loneragan ◽  
Jeremy Prince
Keyword(s):  
Empirical Test ◽  
Estimation Method ◽  
Size Composition ◽  
Cost Effective ◽  
Small Scale ◽  
Empirical Estimation ◽  
Input Parameters ◽  
Maximum Likelihood Methods ◽  
Spawning Potential Ratio ◽  
The Difference

Abstract The spawning potential ratio (SPR) is a well-established biological reference point, and estimates of SPR could be used to inform management decisions for data-poor fisheries. Simulations were used to investigate the utility of the length-based model (LB-SPR) developed in Hordyk et al. (2015). Some explorations of the life history ratios to describe length composition, spawning-per-recruit, and the spawning potential ratio. ICES Journal of Marine Science, 72: 204–216.) to estimate the SPR of a stock directly from the size composition of the catch. This was done by (i) testing some of the main assumptions of the LB-SPR model, including recruitment variability and dome-shaped selectivity, (ii) examining the sensitivity of the model to error in the input parameters, and (iii) completing an initial empirical test for the LB-SPR model by applying it to data from a well-studied species. The method uses maximum likelihood methods to find the values of relative fishing mortality (F/M) and selectivity-at-length that minimize the difference between the observed and the expected length composition of the catch, and calculates the resulting SPR. When parameterized with the correct input parameters, the LB-SPR model returned accurate estimates of F/M and SPR. With high variability in annual recruitment, the estimates of SPR became increasingly unreliable. The usefulness of the LB-SPR method was tested empirically by comparing the results predicted by the method with those for a well-described species with known length and age composition data. The results from this comparison suggest that the LB-SPR method has potential to provide a tool for the cost-effective assessment of data-poor fisheries. However, the model is sensitive to non-equilibrium dynamics, and requires accurate estimates of the three parameters (M/k, L∞, and CVL∞). Care must be taken to evaluate the validity of the assumptions and the biological parameters when the model is applied to data-poor fisheries.

scholarly journals Some explorations of the life history ratios to describe length composition, spawning-per-recruit, and the spawning potential ratio

2014 ◽  
Vol 72 (1) ◽  
pp. 204-216 ◽  
Author(s):  
Adrian Hordyk ◽  
Kotaro Ono ◽  
Keith Sainsbury ◽  
Neil Loneragan ◽  
Jeremy Prince
Keyword(s):  
Life History ◽  
Growth Parameters ◽  
Estimation Method ◽  
Cost Effective ◽  
Analytical Models ◽  
Small Scale ◽  
Natural Mortality ◽  
Von Bertalanffy ◽  
Cost Effective Method ◽  
Spawning Potential Ratio

Abstract Evaluating the status of data-poor fish stocks is often limited by incomplete knowledge of the basic life history parameters: the natural mortality rate (M), the von Bertalanffy growth parameters (L∞ and k), and the length at maturity (Lm). A common approach to estimate these individual parameters has been to use the Beverton–Holt life history invariants, the ratios M/k and Lm/L∞, especially for estimating M. In this study, we assumed no knowledge of the individual parameters, and explored how the information on life history strategy contained in these ratios can be applied to assessing data-poor stocks. We developed analytical models to develop a relationship between M/k and the von Bertalanffy growth curve, and demonstrate the link between the life history ratios and yield- and spawning-per-recruit. We further developed the previously recognized relationship between M/k and yield- and spawning-per-recruit by using information on Lm/L∞, knife-edge selectivity (Lc/L∞), and the ratio of fishing to natural mortality (F/M), to demonstrate the link between an exploited stock's expected length composition, and its spawning potential ratio (SPR), an internationally recognized measurement of stock status. Variation in length-at-age and logistic selectivity patterns were incorporated in the model to demonstrate how SPR can be calculated from the observed size composition of the catch; an advance which has potential as a cost-effective method for assessing data-poor stocks. A companion paper investigates the effects of deviations in the main assumptions of the model on the application of the analytical models developed in this study as a cost-effective method for stock assessment [Hordyk, A. R., Ono, K., Valencia, S., Loneragan, N. R., and Prince, J. D. 2015. A novel length based empirical estimation method of spawning potential ratio (SPR), and tests of its performance, for small-scale, data-poor fisheries. ICES Journal of Marine Science, 72: 217–231].

scholarly journals A simple cost-effective and scale-less empirical approach to harvest strategies

2011 ◽  
Vol 68 (5) ◽  
pp. 947-960 ◽  
Author(s):  
Jeremy D. Prince ◽  
Natalie A. Dowling ◽  
Campbell R. Davies ◽  
Robert A. Campbell ◽  
Dale S. Kolody
Keyword(s):  
Ad Hoc ◽  
Size Composition ◽  
Cost Effective ◽  
Empirical Approach ◽  
Structured Population ◽  
Strategy Evaluation ◽  
Structured Population Dynamics ◽  
Spawning Potential Ratio ◽  
Age Structured ◽  
Harvest Strategy

Abstract Prince, J. D., Dowling, N. A., Davies, C. R., Campbell, R. A., and Kolody, D. S. 2011. A simple cost-effective and scale-less empirical approach to harvest strategies. – ICES Journal of Marine Science, 68: 947–960. An empirical harvest strategy for an Australian longline fishery was developed and tested using harvest strategy evaluation. The approach is based on catch rate and size composition indices and iteratively drives the population towards a target level of spawning potential ratio. The simulation model assumed traditional age-structured population dynamics. The results demonstrate that the empirical approach represents a promising feedback strategy that becomes more precautionary as data errors and recruitment variance increase. Given the urgent need for formal harvest strategies to replace ad hoc decision-making in data-poor fisheries, the approach offers considerable promise. Independent implementation at local scales across the range of a species is speculated to result in management that is robust to uncertainty about stock structure.

Development on Aegir Reeling Pipeline Analyses by Test Validation

2013 ◽  
Author(s):  
Erwan Karjadi ◽  
Helen Boyd ◽  
Reinout van Rooijen ◽  
Harm Demmink ◽  
Thomas Balder
Keyword(s):  
Cost Effective ◽  
Material Model ◽  
Material Behavior ◽  
Small Scale ◽  
Correct Prediction ◽  
Test Program ◽  
Element Analysis ◽  
Bend Tests ◽  
The Difference ◽  
Cyclic Straining

Heerema Marine Contractors (HMC) is entering a new era of laying pipelines using the reel-lay method in order to be more cost effective for deep and shallow water pipeline installation projects. The new Deep water Construction Vessel (DCV) Aegir is designed to be able to reel/J-lay pipelines for a range of pipe dimension and water depth combinations. The paper describes how the full reeling cycles Finite Element Analysis (FEA) of the Aegir have been developed step by step from the development of the bend rig test, spooling-on to spooling-off FE models which is validated by the bend rig test program. The required material test program is performed to characterize the correct material behavior under plastic cyclic straining. The know-how from the validation of the FEA of bend rig tests by performing the bend tests program is used to setup the full-reeling cycles simulation of spooling-on pipeline on the yard and spooling-off pipeline on board of the Aegir. A series of bend rig tests have been performed at Heriot-Watt University. Ovality measurements from the tests are compared with the predicted results from the bend rig FEA simulation model. Based on small scale specimen tests which are performed to describe the proper material behavior under plastic cyclic straining, a new material model has been proposed and discussed to provide a correct prediction of ovalization against the number of bend cycles. Comparison between the bend rig test measurements and the Aegir full reeling cycles simulation results is made by comparing the deformation of the pipe (ovalization) against a number of bend cycles. Discussion is given to justify the difference in the outcomes as well as the representation of the bend tests program for the qualification test program for reeling with the Aegir.

scholarly journals Combined Application of Ozone and Hydrogen Peroxide to Degrade Diesel Contaminants in Soil and Groundwater

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3404
Author(s):  
Wen-Yu Chen ◽  
Prakash Pokhrel ◽  
Ying-Shun Wang ◽  
Sheng-Lung Lin ◽  
Min-Hsin Liu
Keyword(s):  
Hydrogen Peroxide ◽  
Contaminated Soil ◽  
Cost Effective ◽  
Chemical Oxidation ◽  
Injection System ◽  
Small Scale ◽  
Vapor Extraction ◽  
Combined Application ◽  
Order Of Magnitude ◽  
The Difference

Environmental pollution has been a major concern in recent times, and soil and groundwater pollution are areas which have received particular focus. This has led to the development of various remediation techniques such as excavation, soil vapor extraction, bioremediation, chemical oxidation, and so on. Among all remediation techniques, chemical oxidation has been proven to be the most effective and feasible technique around the world. In this study, various combinations of ozone and hydrogen peroxide were used to treat diesel-contaminated soil and groundwater in an experimental setup. Experimental soil and groundwater were prepared with properties similar to the contaminated soil. An ozone generator and a pump injection system were deployed for combining ozone and hydrogen peroxide. Five different experiment batches were prepared based on the hydrogen peroxide concentration and its ratio to the soil. The diesel concentration in the water dropped from 300 mg/L to 7 mg/L in the first hour of treatment, which dropped below the detection limit (0.01 mg/L) thereafter. Similarly, 63.9% degradation was achieved with the combined sparging of ozone and hydrogen peroxide in the soil. Ozone combined with 7% hydrogen peroxide was the most promising combination for removing the contaminants. In addition, this research explored the hydroxyl radical conversion rate of ozone and the perozone, the difference in order of magnitude is greater than one which shows that the perozone has better oxidation capacity than ozone only. The findings of this study show that combining ozone with hydrogen peroxide is a competent and feasible onsite remediation method for diesel contaminants in soil and groundwater. Thus, this method can be applied in local gas stations, accidental spillage sites, and small-scale refineries for onsite treatment in a cost-effective and technically sound way within a short time span.

Urban pollution control strategy: SBR technology to treat agricultural waste from pig farm in Indonesia

2019 ◽  
Vol 2 (2) ◽  
pp. 21
Author(s):  
Lindawati Lindawati
Keyword(s):  
Cost Estimation ◽  
Batch Reactor ◽  
Agricultural Waste ◽  
Cost Effective ◽  
Land Application ◽  
Pig Manure ◽  
Small Scale ◽  
Piggery Wastewater ◽  
Pig Farm ◽  
Number Of Customers

Reduction of food rations and shortages is one of the impacts of the increasing human population. Food sector industries then try to cope with the fast growing number of customers. Agribusiness sector gains its popularity in these recent years, including pig farm. The increase trend of animal farming industry is likely to bring increasing pollution problem unless effective treatment methods are used. The main problems related to the pig farm include odor nuisance and pig manure disposal. The existing land application of piggery wastewater is the traditional way to discharge the wastewater. This may yield in land and water contamination, due to the accumulation of unused nutrients by crop plant. A case study of a large commercial pig farm from Australia is proposed to apply in smaller scale in Indonesia. Operational strategies for the small-scale SBR (Sequencing Batch Reactor) treating piggery effluent were developed based on lab-scale experiments. Due to SBR characteristics, which are money-saving and space-saving, it is very suitable to be applied in urban area. An economic evaluation was made of various process options. The cost estimation showed that SBR is a cost effective process, allowing operational batches to be adjusted to reduce unnecessary aeration cost. A reduction in the aeration cost was achieved by shortening the batch time from 24-h to 8-h. A comparison of three different SBR options showed that smaller size reactors could be more flexible and cost effective when compared with the larger ones.

How the United Kingdom Controls Pharmaceutical Prices and Spending: Learning From Its Experience

2021 ◽  
pp. 002073142199709
Author(s):  
Marc A. Rodwin
Keyword(s):  
United Kingdom ◽  
Cost Effective ◽  
Market Prices ◽  
The United Kingdom ◽  
Generic Market ◽  
Pharmaceutical Spending ◽  
The Difference ◽  
The Government ◽  
Pharmaceutical Prices ◽  
Limit Access

To control costs and improve access, nations can adopt strategies employed in the United Kingdom to control pharmaceutical prices and spending. Current policy evolved from a system created in 1957 that allowed manufacturers to set launch prices, capped manufacturers’ rates of return, and later cut list prices. These policies did not effectively control spending and had limited effects on purchase prices. The United Kingdom currently controls pharmaceutical spending in 4 ways. (a) Since 1999, it has typically paid no more than is cost-effective. (b) Since 2017, for medicines that will have a significant budget impact, National Health Service England seeks discounts from cost-effective prices or seeks to limit access for 2 years to patients with the greatest need. (c) Since 2014, statutes and a voluntary scheme have required branded manufacturers to pay the government rebates to recoup the difference between the global pharmaceutical budget and actual spending. (d) For hospitals, generics and some patented drugs are procured through competitive bidding; community pharmacies are reimbursed through a system that provides an incentive to beat average generic market prices. These policies controlled the growth of spending, with the largest effects following budget controls in 2014. Changes since 2008 have reduced savings, first by paying more than is cost-effective for cancer drugs and then by applying higher cost-effectiveness thresholds for some drugs used to treat cancer and certain other drugs.

scholarly journals Visual Simulation of Detailed Turbulent Water by Preserving the Thin Sheets of Fluid

Symmetry ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 502 ◽  
Author(s):  
Jong-Hyun Kim ◽  
Wook Kim ◽  
Young Kim ◽  
Jung Lee
Keyword(s):  
Turbulent Flows ◽  
Visual Simulation ◽  
Numerical Dissipation ◽  
Small Scale ◽  
Thin Sheets ◽  
Global Flow ◽  
Low Mass ◽  
The Difference ◽  
Water Simulation ◽  
Turbulent Water

When we perform particle-based water simulation, water particles are often increased dramatically because of particle splitting around breaking holes to maintain the thin fluid sheets. Because most of the existing approaches do not consider the volume of the water particles, the water particles must have a very low mass to satisfy the law of the conservation of mass. This phenomenon smears the motion of the water, which would otherwise result in splashing, thereby resulting in artifacts such as numerical dissipation. Thus, we propose a new fluid-implicit, particle-based framework for maintaining and representing the thin sheets and turbulent flows of water. After splitting the water particles, the proposed method uses the ghost density and ghost mass to redistribute the difference in mass based on the volume of the water particles. Next, small-scale turbulent flows are formed in local regions and transferred in a smooth manner to the global flow field. Our results show us the turbulence details as well as the thin sheets of water, thereby obtaining an aesthetically pleasing improvement compared with existing methods.

scholarly journals Diversity minimization through part combination – a Portuguese railway infrastructure case study

2020 ◽  
Vol 7 (1) ◽  
pp. 86-94
Author(s):  
Diogo Rechena ◽  
Luís Sousa ◽  
Virgínia Infante ◽  
Elsa Henriques
Keyword(s):  
Economies Of Scale ◽  
Product Family ◽  
Cost Effective ◽  
Added Value ◽  
Small Scale ◽  
Railway Infrastructure ◽  
Sustainable Services ◽  
Market Needs ◽  
Design Diversity ◽  
Requirement Changes

Abstract With increasing market needs for product and service variety, companies struggle to provide diversity in cost-effective ways. Through standardization of components with a low perceived added value, companies can take advantage of economies of scale while maintaining product diversity. Railway infrastructure managers face similar challenges of providing economically sustainable services while dealing with the costs of maintaining the system diversity. Typically, unintended design diversity stems from design practices in which existing solutions are not reused for new problems and new solutions are rarely planned considering the dynamics of requirement changes. In this paper we provide a methodology to assess how to standardize different designs to minimize design diversity and to assess design divergence in a product family. The developed methodology is able to take into account any set of standardization compatibility constraints that the user can define. The methodology was applied in the context of a small-scale railway infrastructure manager using a dataset of 223 unique designs of functionally similar components from its electrification system. Depending on the activated compatibility constraints, results indicate that over 60% of components can be reduced to a set of 86 unique designs.

Pricing spread options by generalized bivariate edgeworth expansion

2017 ◽  
Vol 04 (02n03) ◽  
pp. 1750017
Author(s):  
Edward P. C. Kao ◽  
Weiwei Xie
Keyword(s):  
Edgeworth Expansion ◽  
Price Difference ◽  
Empirical Estimation ◽  
Strike Price ◽  
Closed Form Solutions ◽  
Spread Options ◽  
Valuation Process ◽  
The Difference ◽  
Spread Option ◽  
Underlying Processes

A spread option is a contingent claim whose underlying is the price difference between two assets. For a call, the holder of the option receives the difference, if positive, between the price difference and the strike price. Otherwise, the holder receives nothing. Spread options trade in large volume in financial, fixed-income, commodity, and energy industries. It is well known that pricing of spread options does not admit closed-form solutions even under a geometric Brownian motion paradigm. When price dynamics experience stochastic volatilities and/or jumps, the valuation process becomes more challenging. Following the seminal work of Jarrow and Judd, we propose the use of Edgeworth expansion to approximate the call price. In the spirit of Pearson, we reduce the cumbersome computation inherent in Edgeworth expansion to single numerical integrations. For an arbitrary bivariate price process, we show that once its product cumulants are available, either by virtue of the structural properties of the underlying processes or by empirical estimation using market data, the approach enables analysts to approximate the call price easily. Specifically, the call prices so estimated capture the correlation, skewness, and kurtosis of the two underlying price processes. As such, the approach is useful for approximate valuations based on Lévy-based models.

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