The Experts below are selected from a list of 28815 Experts worldwide ranked by ideXlab platform
Tien-fu Lu - One of the best experts on this subject based on the ideXlab platform.
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3d Stockpile modelling and quality calculation for continuous Stockpile management
International Journal of Mineral Processing, 2015Co-Authors: Shi Zhao, Tien-fu Lu, Ben Koch, Alan HurdsmanAbstract:Abstract This paper describes an innovative method to calculate the quality of a Stockpile in real-time to improve the efficiency in Stockpile blending operations. A Stockpile is modelled as a grid of voxels (octants), which are used as geometric elements for both quality calculations and result storage. The quality calculation is based on the real geometric shape of the Stockpile which is measured by a laser scanner. Furthermore, a BWR (Bucket Wheel Reclaimer), which is treated as a mobile robot arm, is incorporated into this model to predicate the quality of the reclaimed material. Thus, this 3D quality embedded model can be used to calculate, plan, control and predict the quality level of iron ore being stacked and/or reclaimed with a great degree of accuracy. This model provides an opportunity to monitor and track quality data throughout the blending operations. It will lead to proactive and continuous blending activities that fundamentally improve quality control and increase efficiency in Stockpile management.
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Sickle-shaped voxel approach to enhance automatic reclaiming operation using bucket wheel reclaimer
2013 IEEE 8th Conference on Industrial Electronics and Applications (ICIEA), 2013Co-Authors: Tien-fu LuAbstract:Bulk material is currently reclaimed either manually or semi-automatically due to the lack of integration between Stockpile and bucket wheel reclaimer (BWR). Stockpile is stacked in Cartesian coordinate whereas BWR operates in its joint parameter space. The voxel based approach was introduced to improve the extent of automation in reclaiming. In which, Stockpile is treated as a combination of small volumes called voxels instead of treating as a single volume. However, the fully automatic reclaiming still has not been realized since voxelization is carried out without considering the reclaiming pattern of the reclaimer. The sickle-shaped voxel is introduced in this paper based on the BWR kinematics to coordinate between the reclaimer and Stockpile in voxelization. In addition, solving of the inverse kinematics of a four degrees of freedom BWR and modeling of Stockpile contours are conducted in this study for voxelization of a Stockpile into sickle-shaped voxels.
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A FAST Stockpile SIMULATION ENGINE AND ITS APPLICATION IN MINERAL ORE HANDLING
International Journal of Modeling Simulation and Scientific Computing, 2013Co-Authors: Tien-fu Lu, Shihong XuAbstract:This paper presents structures and principles of a fast Stockpile simulation engine that enhances automatic material process by providing accurate digital information of material quality distribution within Stockpiles. Compared with traditional measurement-based approaches, our simulation technology reduces operation cost by eliminating frequent physical measuring; improves operation accuracy through all-time whole-area contour simulation (instead of measuring a few positions of material layers now and then); and speeds the process through fast simulation and instant response to quality information query. Based on simplified grain dynamics and cellular automata models, the technology can achieve real-time/super-real-time simulation, which is critical to be adopted by the industry. Application of the technology in analyzing mineral ores handling is also discussed.
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ICARCV - Stockpile modelling using mobile laser scanner for quality grade control in Stockpile management
2012 12th International Conference on Control Automation Robotics & Vision (ICARCV), 2012Co-Authors: Shi Zhao, Tien-fu Lu, Ben Koch, Alan HurdsmanAbstract:The delivery of a relatively constant quality grade of iron ore is crucial to Australia mining. As a buffer, blending and target grading system, Stockpile plays a key role in the iron ore quality control. However, the shape of the Stockpile, the quantity housed within the Stockpile and the quality grade inside the Stockpile are currently unavailable to operators. Therefore, this paper describes a method to generate 3D model of a Stockpile with multiple layers using laser to keep tracking the shape changes caused by the stacking and reclaiming operations. Using this 3D model, the volume can be easily calculated anytime. Experiments conducted in laboratory environment indicate good results and proved that the 3D modelling method is accurate and efficient.
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Stockpile modelling using mobile laser scanner for quality grade control in Stockpile management
2012 12th International Conference on Control Automation Robotics & Vision (ICARCV), 2012Co-Authors: Shi Zhao, Tien-fu Lu, Ben Koch, Alan HurdsmanAbstract:The delivery of a relatively constant quality grade of iron ore is crucial to Australia mining. As a buffer, blending and target grading system, Stockpile plays a key role in the iron ore quality control. However, the shape of the Stockpile, the quantity housed within the Stockpile and the quality grade inside the Stockpile are currently unavailable to operators. Therefore, this paper describes a method to generate 3D model of a Stockpile with multiple layers using laser to keep tracking the shape changes caused by the stacking and reclaiming operations. Using this 3D model, the volume can be easily calculated anytime. Experiments conducted in laboratory environment indicate good results and proved that the 3D modelling method is accurate and efficient.
Kimberly M Thompson - One of the best experts on this subject based on the ideXlab platform.
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framework for optimal global vaccine Stockpile design for vaccine preventable diseases application to measles and cholera vaccines as contrasting examples
Risk Analysis, 2016Co-Authors: Kimberly M Thompson, Radboud Duintjer J TebbensAbstract:Managing the dynamics of vaccine supply and demand represents a significant challenge with very high stakes. Insufficient vaccine supplies can necessitate rationing, lead to preventable adverse health outcomes, delay the achievements of elimination or eradication goals, and/or pose reputation risks for public health authorities and/or manufacturers. This article explores the dynamics of global vaccine supply and demand to consider the opportunities to develop and maintain optimal global vaccine Stockpiles for universal vaccines, characterized by large global demand (for which we use measles vaccines as an example), and nonuniversal (including new and niche) vaccines (for which we use oral cholera vaccine as an example). We contrast our approach with other vaccine Stockpile optimization frameworks previously developed for the United States pediatric vaccine Stockpile to address disruptions in supply and global emergency response vaccine Stockpiles to provide on-demand vaccines for use in outbreaks. For measles vaccine, we explore the complexity that arises due to different formulations and presentations of vaccines, consideration of rubella, and the context of regional elimination goals. We conclude that global health policy leaders and stakeholders should procure and maintain appropriate global vaccine rotating stocks for measles and rubella vaccine now to support current regional elimination goals, and should probably also do so for other vaccines to help prevent and control endemic or epidemic diseases. This work suggests the need to better model global vaccine supplies to improve efficiency in the vaccine supply chain, ensure adequate supplies to support elimination and eradication initiatives, and support progress toward the goals of the Global Vaccine Action Plan.
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characterization of outbreak response strategies and potential vaccine Stockpile needs for the polio endgame
BMC Infectious Diseases, 2016Co-Authors: Radboud Duintjer J Tebbens, Mark A Pallansch, Steven G F Wassilak, Stephen L Cochi, Kimberly M ThompsonAbstract:Following successful eradication of wild polioviruses and planned globally-coordinated cessation of oral poliovirus vaccine (OPV), national and global health leaders may need to respond to outbreaks from reintroduced live polioviruses, particularly vaccine-derived polioviruses (VDPVs). Preparing outbreak response plans and assessing potential vaccine needs from an emergency Stockpile require consideration of the different national risks and conditions as they change with time after OPV cessation. We used an integrated global model to consider several key issues related to managing poliovirus risks and outbreak response, including the time interval during which monovalent OPV (mOPV) can be safely used following homotypic OPV cessation; the timing, quality, and quantity of rounds required to stop transmission; vaccine Stockpile needs; and the impacts of vaccine choices and surveillance quality. We compare the base case scenario that assumes aggressive outbreak response and sufficient mOPV available from the Stockpile for all outbreaks that occur in the model, with various scenarios that change the outbreak response strategies. Outbreak response after OPV cessation will require careful management, with some circumstances expected to require more and/or higher quality rounds to stop transmission than others. For outbreaks involving serotype 2, using trivalent OPV instead of mOPV2 following cessation of OPV serotype 2 but before cessation of OPV serotypes 1 and 3 would represent a good option if logistically feasible. Using mOPV for outbreak response can start new outbreaks if exported outside the outbreak population into populations with decreasing population immunity to transmission after OPV cessation, but failure to contain outbreaks resulting in exportation of the outbreak poliovirus may represent a greater risk. The possibility of mOPV use generating new long-term poliovirus excretors represents a real concern. Using the base case outbreak response assumptions, we expect over 25 % probability of a shortage of Stockpiled filled mOPV vaccine, which could jeopardize the achievement of global polio eradication. For the long term, responding to any poliovirus reintroductions may require a global IPV Stockpile. Despite the risks, our model suggests that good risk management and response strategies can successfully control most potential outbreaks after OPV cessation. Health leaders should carefully consider the numerous outbreak response choices that affect the probability of successfully managing poliovirus risks after OPV cessation.
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optimal vaccine Stockpile design for an eradicated disease application to polio
Vaccine, 2010Co-Authors: Radboud Duintjer J Tebbens, Mark A Pallansch, James P Alexander, Kimberly M ThompsonAbstract:Eradication of a disease promises significant health and financial benefits. Preserving those benefits, hopefully in perpetuity, requires preparing for the possibility that the causal agent could re-emerge (unintentionally or intentionally). In the case of a vaccine-preventable disease, creation and planning for the use of a vaccine Stockpile becomes a primary concern. Doing so requires consideration of the dynamics at different levels, including the Stockpile supply chain and transmission of the causal agent. This paper develops a mathematical framework for determining the optimal management of a vaccine Stockpile over time. We apply the framework to the polio vaccine Stockpile for the post-eradication era and present examples of solutions to one possible framing of the optimization problem. We use the framework to discuss issues relevant to the development and use of the polio vaccine Stockpile, including capacity constraints, production and filling delays, risks associated with the Stockpile, dynamics and uncertainty of vaccine needs, issues of funding, location, and serotype dependent behavior, and the implications of likely changes over time that might occur. This framework serves as a helpful context for discussions and analyses related to the process of designing and maintaining a Stockpile for an eradicated disease.
Radboud Duintjer J Tebbens - One of the best experts on this subject based on the ideXlab platform.
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framework for optimal global vaccine Stockpile design for vaccine preventable diseases application to measles and cholera vaccines as contrasting examples
Risk Analysis, 2016Co-Authors: Kimberly M Thompson, Radboud Duintjer J TebbensAbstract:Managing the dynamics of vaccine supply and demand represents a significant challenge with very high stakes. Insufficient vaccine supplies can necessitate rationing, lead to preventable adverse health outcomes, delay the achievements of elimination or eradication goals, and/or pose reputation risks for public health authorities and/or manufacturers. This article explores the dynamics of global vaccine supply and demand to consider the opportunities to develop and maintain optimal global vaccine Stockpiles for universal vaccines, characterized by large global demand (for which we use measles vaccines as an example), and nonuniversal (including new and niche) vaccines (for which we use oral cholera vaccine as an example). We contrast our approach with other vaccine Stockpile optimization frameworks previously developed for the United States pediatric vaccine Stockpile to address disruptions in supply and global emergency response vaccine Stockpiles to provide on-demand vaccines for use in outbreaks. For measles vaccine, we explore the complexity that arises due to different formulations and presentations of vaccines, consideration of rubella, and the context of regional elimination goals. We conclude that global health policy leaders and stakeholders should procure and maintain appropriate global vaccine rotating stocks for measles and rubella vaccine now to support current regional elimination goals, and should probably also do so for other vaccines to help prevent and control endemic or epidemic diseases. This work suggests the need to better model global vaccine supplies to improve efficiency in the vaccine supply chain, ensure adequate supplies to support elimination and eradication initiatives, and support progress toward the goals of the Global Vaccine Action Plan.
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characterization of outbreak response strategies and potential vaccine Stockpile needs for the polio endgame
BMC Infectious Diseases, 2016Co-Authors: Radboud Duintjer J Tebbens, Mark A Pallansch, Steven G F Wassilak, Stephen L Cochi, Kimberly M ThompsonAbstract:Following successful eradication of wild polioviruses and planned globally-coordinated cessation of oral poliovirus vaccine (OPV), national and global health leaders may need to respond to outbreaks from reintroduced live polioviruses, particularly vaccine-derived polioviruses (VDPVs). Preparing outbreak response plans and assessing potential vaccine needs from an emergency Stockpile require consideration of the different national risks and conditions as they change with time after OPV cessation. We used an integrated global model to consider several key issues related to managing poliovirus risks and outbreak response, including the time interval during which monovalent OPV (mOPV) can be safely used following homotypic OPV cessation; the timing, quality, and quantity of rounds required to stop transmission; vaccine Stockpile needs; and the impacts of vaccine choices and surveillance quality. We compare the base case scenario that assumes aggressive outbreak response and sufficient mOPV available from the Stockpile for all outbreaks that occur in the model, with various scenarios that change the outbreak response strategies. Outbreak response after OPV cessation will require careful management, with some circumstances expected to require more and/or higher quality rounds to stop transmission than others. For outbreaks involving serotype 2, using trivalent OPV instead of mOPV2 following cessation of OPV serotype 2 but before cessation of OPV serotypes 1 and 3 would represent a good option if logistically feasible. Using mOPV for outbreak response can start new outbreaks if exported outside the outbreak population into populations with decreasing population immunity to transmission after OPV cessation, but failure to contain outbreaks resulting in exportation of the outbreak poliovirus may represent a greater risk. The possibility of mOPV use generating new long-term poliovirus excretors represents a real concern. Using the base case outbreak response assumptions, we expect over 25 % probability of a shortage of Stockpiled filled mOPV vaccine, which could jeopardize the achievement of global polio eradication. For the long term, responding to any poliovirus reintroductions may require a global IPV Stockpile. Despite the risks, our model suggests that good risk management and response strategies can successfully control most potential outbreaks after OPV cessation. Health leaders should carefully consider the numerous outbreak response choices that affect the probability of successfully managing poliovirus risks after OPV cessation.
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optimal vaccine Stockpile design for an eradicated disease application to polio
Vaccine, 2010Co-Authors: Radboud Duintjer J Tebbens, Mark A Pallansch, James P Alexander, Kimberly M ThompsonAbstract:Eradication of a disease promises significant health and financial benefits. Preserving those benefits, hopefully in perpetuity, requires preparing for the possibility that the causal agent could re-emerge (unintentionally or intentionally). In the case of a vaccine-preventable disease, creation and planning for the use of a vaccine Stockpile becomes a primary concern. Doing so requires consideration of the dynamics at different levels, including the Stockpile supply chain and transmission of the causal agent. This paper develops a mathematical framework for determining the optimal management of a vaccine Stockpile over time. We apply the framework to the polio vaccine Stockpile for the post-eradication era and present examples of solutions to one possible framing of the optimization problem. We use the framework to discuss issues relevant to the development and use of the polio vaccine Stockpile, including capacity constraints, production and filling delays, risks associated with the Stockpile, dynamics and uncertainty of vaccine needs, issues of funding, location, and serotype dependent behavior, and the implications of likely changes over time that might occur. This framework serves as a helpful context for discussions and analyses related to the process of designing and maintaining a Stockpile for an eradicated disease.
Janet A Jokela - One of the best experts on this subject based on the ideXlab platform.
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Stockpile levels for pediatric vaccines how much is enough
Vaccine, 2006Co-Authors: Sheldon H Jacobson, Edward C Sewell, Ruben A Proano, Janet A JokelaAbstract:In recent years, several factors have led to pediatric vaccine manufacturers experiencing vaccine production interruptions that resulted in vaccine supply shortages. One unfortunate consequence of such events is that not all children in the United States could be vaccinated on time, as set forth by the Recommended Childhood Immunization Schedule, and hence, created the potential for epidemic outbreaks of several childhood diseases. The Centers for Disease Control and Prevention (CDC) have responded to such events by releasing vaccine supplies from the national pediatric vaccine Stockpiles, which were designed to mitigate the impact of vaccine production interruptions. This paper analyzes the CDC-proposed vaccine Stockpile levels using a stochastic inventory model. The results from this analysis examine the adequacy of the proposed pediatric vaccine Stockpile levels, as well as provide insights into what the appropriate pediatric vaccine Stockpile levels should be to achieve prespecified vaccination coverage rates. Given that the average pediatric vaccine production interruption has lasted more than 1 year, the model is used to compute appropriate pediatric vaccine Stockpile levels sufficient to absorb the effect of such vaccine production interruptions. The level of funding needed to create such pediatric vaccine Stockpile levels is also reported.
Jodie Mcvernon - One of the best experts on this subject based on the ideXlab platform.
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Reducing disease burden in an influenza pandemic by targeted delivery of neuraminidase inhibitors: mathematical models in the Australian context
BMC Infectious Diseases, 2016Co-Authors: Robert Moss, Aeron C Hurt, Allen C. Cheng, James M Mccaw, Jodie McvernonAbstract:BackgroundMany nations maintain Stockpiles of neuraminidase inhibitor (NAI) antiviral agents for use in influenza pandemics to reduce transmission and mitigate the course of clinical infection. Pandemic preparedness plans include the use of these Stockpiles to deliver proportionate responses, informed by emerging evidence of clinical impact. Recent uncertainty about the effectiveness of NAIs has prompted these nations to reconsider the role of NAIs in pandemic response, with implications for pandemic planning and for NAI Stockpile size.MethodsWe combined a dynamic model of influenza epidemiology with a model of the clinical care pathways in the Australian health care system to identify effective NAI strategies for reducing morbidity and mortality in pandemic events, and the Stockpile requirements for these strategies. The models were informed by a 2015 assessment of NAI effectiveness against susceptibility, pathogenicity, and transmission of influenza.ResultsLiberal distribution of NAIs for early treatment in outpatient settings yielded the greatest benefits in all of the considered scenarios. Restriction of community-based treatment to risk groups was effective in those groups, but failed to prevent the large proportion of cases arising from lower risk individuals who comprise the majority of the population.ConclusionsThese targeted strategies are only effective if they can be deployed within the constraints of existing health care infrastructure. This finding highlights the critical importance of identifying optimal models of care delivery for effective emergency health care response.
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understanding australia s influenza pandemic policy on the strategic use of the antiviral drug Stockpile
The Medical Journal of Australia, 2009Co-Authors: James M Mccaw, James G Wood, Emma S Mcbryde, Terry Nolan, Joseph T Wu, Marc Lipsitch, Jodie McvernonAbstract:With the emergence of H1N1 influenza 09 (novel human swine influenza A[H1N1] 2009), efforts to control the spread and mitigate the impact of this virus have been implemented. The Australian health management plan for pandemic influenza (2008)1 (AHMPPI) outlines a range of strategies aimed at eliminating an outbreak where possible (the “Contain” response), or reducing transmission sufficiently to allow distribution of a targeted vaccine (the “Sustain” response). Following evidence of sustained transmission within Victoria in May 2009, state and territory health departments began implementing the Contain response, with a switch to a modified Sustain response in Victoria within weeks. The AHMPPI recommends liberal distribution of the Stockpile of neuraminidase inhibitors (oseltamivir, zanamivir) to constrain influenza transmission.1 This policy was based on modelling studies synthesising the best available evidence, including clear demonstration of the efficacy of antiviral drugs to prevent secondary infection in randomised controlled trials.2,3 Notwithstanding revision of the AHMPPI on 17 June 2009 to incorporate the present “Protect” phase, understanding the rationale for and defining the operational implications of the initial recommendations for antiviral drug use are priorities. Translation of evidence from epidemiological trials into pandemic policy is challenging, given the complexity of real-world factors that influence intervention effectiveness. For example, as has been observed with many vaccines, drug effects on transmission have far greater impact when implemented across a whole population. The chosen antiviral deployment strategy needs to take into account not only the direct effects benefiting the treated individual, but also indirect effects due to changes in subsequent transmission. In a rapidly growing epidemic, these secondary effects are critical to determining the optimal deployment strategy. Mathematical modelling provides a way to systematically investigate these issues. Using a diverse set of assumptions and frameworks, models consistently demonstrate that for a country with a sufficiently large Stockpile of antiviral drugs, augmenting a patient treatment policy with targeted post-exposure prophylaxis represents a more efficient use of the Stockpile than treatment alone.4–6 Modelling performed in the Australian context, where the number of Stockpiled antiviral drug courses is 40% of the population size, has demonstrated that extensive drug distribution for preventive purposes does not compromise the ability to treat infected patients.6 It was therefore recommended in the AHMPPI that prophylaxis should be provided to as many readily identifiable contacts as possible during the Contain response, with continued provision to household contacts during the Sustain response. Provision of continuous pre-exposure prophylaxis to health care workers was also recommended, as this additive burden on the Stockpile would not substantially impede efforts to delay the pandemic. Lessons learned so far in the effort to implement these recommendations have highlighted the importance of clear case definitions to guide treatment, particularly when disease is mild. Delays in confirming infection, associated with finite laboratory resources, posed significant challenges for front-line health care workers. This practical issue must be addressed should deployment of existing Stockpile reserves be recommended in coming years, as potentially more virulent variants of the present pandemic strain arise. Meanwhile, further research and policy development are required on a largely unaddressed issue. A transmissible drug-resistant variant of the pandemic strain may arise either by de-novo mutation or by reassortment with drug-resistant seasonal strains (eg, the oseltamivir-resistant 2008 seasonal H1N1 strain carrying the H274Y mutation [histidine-to-tyrosine mutation at codon 274]), and its spread would be favoured by widespread antiviral use. The effort to delay the appearance of such a variant might stimulate a change to the recommended strategies for antiviral deployment. To date, novel H1N1 viruses demonstrating oseltamivir resistance have been isolated from individuals in Denmark and Japan.7 Several published models have been used to investigate the potential consequences of antiviral drug resistance and all demonstrate that emergence of a transmissible drug-resistant variant will reduce the effectiveness of antiviral distribution strategies, with obvious consequences for their utility in “buying time” before a targeted vaccine becomes available. Two recent studies have investigated strategies for reducing the negative impact of drug resistance.8,9 Both considered the case where the main Stockpile (ie, oseltamivir) is supplemented with a smaller secondary Stockpile of another drug (eg, zanamivir). One study considered four strategies for antiviral drug distribution when both drugs are available for treatment and prophylaxis.8 It was concluded that a strategy whereby the smaller Stockpile (drug B) is reserved for treatment, while the main Stockpile (drug A) is used for prophylaxis, will most effectively delay the peak of the epidemic and result in the lowest overall level of drug resistance. Alternative strategies of random allocation of drug A or drug B to each individual who is prescribed an antiviral drug, or use of drug B followed by drug A, were also shown to have significant benefits over a single-drug policy. Cycling between one drug and the other over a period of weeks or months was shown to be a high-risk strategy and cannot be recommended. Treatment strategies were also considered in the other study, which demonstrated that using a small amount of drug B followed by drug A will reduce the overall attack and greatly reduce the resistant attack rate.9 In addition, the global implications of a two-drug strategy were considered, taking into account regular entry of infectious individuals into countries and regions over the course of a pandemic. It was shown that if the primary source country implements a strategic two-drug distribution policy, any country into which strains are subsequently introduced will gain a significant benefit from implementing a similar policy. Both these studies provide strong evidence for jurisdictions to consider acquisition of a secondary drug to supplement their primary drug Stockpile. Whether the Stockpiles are deployed in order (drug B, then drug A) or separated for use as treatment only and prophylaxis only would largely depend on logistical constraints and overall feasibility of the alternative strategies. Either strategy is likely to provide significant benefits compared with deployment of a single drug. In a climate of great uncertainty surrounding characteristics of the current influenza outbreak,10 the challenge worldwide is for jurisdictions to implement flexible evidence-based policies for antiviral Stockpile distribution that maximise their effectiveness.
