Which Control Strategies and Configurations Affect Performance? Evidence from Large Scale Outsourcing Arrangements

2011 ◽  
Author(s):  
Pankaj Nagpal ◽  
Kalle J. Lyytinen ◽  
Richard J. Boland
Keyword(s):  
Large Scale ◽  
Control Strategies

scholarly journals Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Huo ◽  
Jing Chen ◽  
Shigui Ruan
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Rate ◽  
Control Strategies ◽  
Herd Immunity ◽  
Antibody Prevalence ◽  
Screening Process ◽  
Vaccination Programs ◽  
Prevalence Level ◽  
The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

scholarly journals A Full-Newton AC-DC Power Flow Methodology for HVDC Multi-Terminal Systems and Generic DC Network Representation

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1658
Author(s):  
Leandro Almeida Vasconcelos ◽  
João Alberto Passos Filho ◽  
André Luis Marques Marcato ◽  
Giovani Santiago Junqueira
Keyword(s):  
Power Systems ◽  
Direct Current ◽  
Power Flow ◽  
Large Scale ◽  
Flow Problem ◽  
Control Strategies ◽  
Problem Formulation ◽  
Expansion Planning ◽  
Dc Power ◽  
Power Flow Problem

The use of Direct Current (DC) transmission links in power systems is increasing continuously. Thus, it is important to develop new techniques to model the inclusion of these devices in network analysis, in order to allow studies of the operation and expansion planning of large-scale electric power systems. In this context, the main objective of this paper is to present a new methodology for a simultaneous AC-DC power flow for a multi-terminal High Voltage Direct Current (HVDC) system with a generic representation of the DC network. The proposed methodology is based on a full Newton formulation for solving the AC-DC power flow problem. Equations representing the converters and steady-state control strategies are included in a power flow problem formulation, resulting in an expanded Jacobian matrix of the Newton method. Some results are presented based on HVDC test systems to confirm the effectiveness of the proposed approach.

The Control Strategy Study of Doubly-Fed Wind Turbine Participated in Frequency Regulation

2012 ◽  
Vol 512-515 ◽  
pp. 788-793
Author(s):  
Xiao Hua Zhou ◽  
Ming Qiang Wang ◽  
Wei Wei Zou
Keyword(s):  
Wind Turbine ◽  
Control Strategy ◽  
Large Scale ◽  
Control Strategies ◽  
Frequency Control ◽  
Frequency Regulation ◽  
Strategy Study ◽  
Fuzzy Control Strategy ◽  
Doubly Fed ◽  
System Frequency

Traditional decoupling control strategy of doubly-fed induction generator (DFIG) wind turbine makes little contribution to system inertia and do not participate in the system frequency control, the synchronization of large-scale wind power requires wind turbine have the ability to participate in the regulation of power system frequency. This paper adds a frequency control segment to traditional DFIG wind turbine and considers the doubly-fed wind turbine operating on the state of the super-synchronous speed, by analysis the effect of inertia and proportional control strategies, a fuzzy control strategy which combines the advantages of the former two control strategies is proposed, simulation results show that this control strategy can more effectively improve the system frequency response.

scholarly journals Oral Tobaccco and Mortality in India

2016 ◽  
Vol 7 ◽  
pp. IJCM.S25889 ◽  
Author(s):  
Priya Mohan ◽  
Harry A. Lando
Keyword(s):  
Tobacco Control ◽  
Health Care Professionals ◽  
Large Scale ◽  
Control Strategies ◽  
Control Policy ◽  
Control Measures ◽  
Educational Institutions ◽  
Regional Studies ◽  
Gender And Education ◽  
Indian Context

This comprehensive review includes large-scale pan-India surveys and regional studies. Every aspect of smokeless tobacco, including variations in social, economic, demographic, gender, and education stratifiers, is presented. This evidence-based presentation thereby provides insight not only to assess the burden but can serve as a base, leading to the development and encouragement of research in closing the existing gaps in knowledge. It can also provide a track to formulate tobacco control strategies as well as to reinforce and potentially guide tobacco control policy aimed at addressing the tailored needs in the Indian context. The recommendations expand the tobacco control spectrum and are the first of their kind in the literature to focus on cessation programs as a paramedical subject to draw the attention of not only policymakers but also to integrate medical and dental educational institutions, health care professionals, and tobacco users to synergistically develop successful tobacco control measures.

scholarly journals Robustness Comparison of Synthetic Inertia Strategies for Doubly Fed Induction Generators under Different Operating Conditions

2020 ◽  
Author(s):  
Paulo Andrade Souza ◽  
Renan R. dos Santos ◽  
Manoelito C. N. Filho ◽  
Daniel Barbosa ◽  
Luciano Sales Barros
Keyword(s):  
Wind Energy ◽  
Large Scale ◽  
Control Strategies ◽  
Renewable Energy Sources ◽  
Operating Conditions ◽  
Wind Condition ◽  
Primary Control ◽  
Parameter Uncertainties ◽  
Doubly Fed ◽  
Frequency Behavior

Due to the increasing penetration of Renewable Energy Sources (RES) such as wind energy in electrical grids, Wind Energy Conversion Systems (WECS) participation in primary control is becoming required including the Doubly Fed Induction Generator (DFIG)-based WECS. High integration of large scale DFIG-based WECS brings new challenges to their primary control support, and more strongly due to the wind condition and grid parameter uncertainties. One of the most used types of control strategy for DFIG-based WECS primary support is the synthetic inertia, however, robustness of these techniques have not been tested. In this work three synthetic inertia control strategies will be tested under different operating conditions of wind speed, frequency and voltage sag. For testing the DFIG-based WECS, it was modeled on ATP including its control systems and the results quantified the controllers robustness on the tested controllers with respect to transient frequency behavior.

scholarly journals Innate Immune Defenses Induced by CpG Do Not Promote Vaccine-Induced Protection against Foot-and-Mouth Disease Virus in Pigs

2009 ◽  
Vol 16 (8) ◽  
pp. 1151-1157 ◽  
Author(s):  
M. P. Alves ◽  
L. Guzylack-Piriou ◽  
V. Juillard ◽  
J.-C. Audonnet ◽  
T. Doel ◽  
...  
Keyword(s):  
Disease Virus ◽  
Large Scale ◽  
Control Strategies ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Innate Immune ◽  
Noticeable Effect ◽  
Mouth Disease Virus ◽  
Foot And Mouth ◽  
Natural Hosts

ABSTRACT Emergency vaccination as part of the control strategies against foot-and-mouth disease virus (FMDV) has the potential to limit virus spread and reduce large-scale culling. To reduce the time between vaccination and the onset of immunity, immunostimulatory CpG was tested for its capacity to promote early protection against FMDV challenge in pigs. To this end, CpG 2142, an efficient inducer of alpha interferon, was injected intramuscularly. Increased transcription of Mx1, OAS, and IRF-7 was identified as a sensitive measurement of CpG-induced innate immunity, with increased levels detectable to at least 4 days after injection of CpG formulated with Emulsigen. Despite this, CpG combined with an FMD vaccine did not promote protection. Pigs vaccinated 2 days before challenge had disease development, which was at least as acute as that of unvaccinated controls. All pigs vaccinated 7 days before challenge were protected without a noticeable effect of CpG. In summary, our results demonstrate the caution required when translating findings from mouse models to natural hosts of FMDV.

Wafer Scale Modeling and Control for Yield Improvement in Wafer Planarization

2002 ◽  
Author(s):  
Sutee Eamkajornsiri ◽  
Ranga Narayanaswami ◽  
Abhijit Chandra
Keyword(s):  
Material Removal Rate ◽  
Integrated Circuit ◽  
Material Removal ◽  
Large Scale ◽  
Removal Rate ◽  
Control Strategies ◽  
Elastic Half Space ◽  
Modeling And Control ◽  
Planarization Process ◽  
Curvature Control

Chemical mechanical polishing (CMP) is a planarization process that produces high quality surfaces both locally and globally. It is one of the key process steps during the fabrication of very large scale integrated (VLSI) chips in integrated circuit (IC) manufacturing. CMP consists of a chemical process and a mechanical process being performed together to reduce height variation across a wafer. High and reliable wafer yield, which is dependent upon uniformity of the material removal rate across the entire wafer, is of critical importance in the CMP process. In this paper, the variations in material removal rate (MRR) variation across the wafer are analytically modeled assumimg a rigid wafer and a flexible polishing pad. The wafer pad contact is modeled as the indentation of a rigid indenter on an elastic half-space. Load and curvature control strategies are investigated for improving the wafer yield. The notion of curvature control is entirely new and has not been addressed in the literature. The control strategy is based on minimizing a moment function that represents the wafer curvature and the height of the oxide layer left for material removal. Simulation results indicate that curvature control can improve wafer yield significantly, and is more effective than just the load control.

Effect of Design Parameters on the Performance of Thermal Energy Storage Systems

Solar Energy ◽  
2004 ◽  
Author(s):  
Gregor P. Henze
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Large Scale ◽  
Control Strategies ◽  
Storage System ◽  
Operating Cost ◽  
Energy Storage System ◽  
Design Parameters ◽  
Wide Range

This paper describes simulation-based results of a large-scale investigation of a commercial cooling plant including a thermal energy storage system. A cooling plant with an ice-on-coil system with external melt and a reciprocating compressor operating in a large office building was analyzed under four different control strategies. Optimal control as the strategy that minimizes the total operating cost (demand and energy charges) served as a benchmark to assess the performance of the three conventional controls. However, all control strategies depend on properly selected design parameters. The storage and chiller capacities as the primary design parameters were varied over a wide range and the dependence of the system’s cost saving performance on these parameters was evaluated.

Selection and Validation of Suitable Reference Genes for RT-qPCR Analysis in Apolygus lucorum (Hemiptera: Miridae)

2019 ◽  
Vol 113 (1) ◽  
pp. 451-460
Author(s):  
Jing Luo ◽  
Aoli Wang ◽  
Yanxia Cheng ◽  
Haoling Rong ◽  
Libin Guo ◽  
...  
Keyword(s):  
Reference Genes ◽  
Large Scale ◽  
Control Strategies ◽  
Quantitative Polymerase Chain Reaction ◽  
Life Stage ◽  
Genetic Studies ◽  
Apolygus Lucorum ◽  
Economic Significance ◽  
Stability Ranking ◽  
Suitable Reference

Abstract Apolygus lucorum (Meyer-Dür) is a destructive pest to >280 plants. Major economic significance and pesticide resistance issues have created a need for integrated pest management (e.g., RNAi, entomopathogen-based bioinsecticides) for A. lucorum. To better develop these control strategies, large-scale genetic studies involving gene-expression analysis are required and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is the most commonly used method. However, there have been no reports on appropriate reference genes in A. lucorum. Here, we evaluated nine widely utilized reference genes including EF1γ, RPL32, RPL27, SDH, TBP, ACT, ACT2, GAPDH, and βTUB for their expression stabilities in A. lucorum under five different conditions i.e., life stage, tissue, sex, dsRNA injection, and entomopathogen infection. Based on the gene stability ranking calculated by RefFinder, which integrates four algorithms (geNorm, delta Ct method, NormFinder, and BestKeeper), we recommend RPL27 and RPL32 as the most appropriate reference genes for molecular studies in different life stages and tissues; GAPDH and EF1γ for different sexes and entomopathogen infection studies; and RPL27 and EF1γ for RNAi studies. The results of this study will help improve the accuracy and reliability for normalizing the RT-qPCR data for further molecular analysis in A. lucorum.

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