Global Search through Sampling Using a PDF

Author(s):  
Benny Raphael ◽  
Ian F. C. Smith
Keyword(s):  
Author(s):  
Daojiong Zha

AbstractChina is a key player, not just an actor, in the global search for health security. Reiteration of this point is useful for International Relations studies, which often portray China as a factor to contend with, especially given the background of the country as the first to report the outbreak of the COVID-19 pandemic. This paper adopts an analytical framework developed through a summary of routines in Chinese engagement in global health from a practitioner’s perspective: aid, interdependence, governance and knowledge. These are the core elements in a country’s pursuit of engagement with the rest of the world. After the introduction, the second section of the paper reviews contributions from China in the history of global plague control over the past century. The third section discusses structural issues affecting access to vaccines, which are essential for bringing COVID-19 under effective control. The fourth section identifies a number of challenges China is facing in global health governance. The final section offers a few concluding thoughts, reiterating the nature of interdependence in the global search for enhancement of health security.


Geophysics ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. R767-R781 ◽  
Author(s):  
Mattia Aleardi ◽  
Silvio Pierini ◽  
Angelo Sajeva

We have compared the performances of six recently developed global optimization algorithms: imperialist competitive algorithm, firefly algorithm (FA), water cycle algorithm (WCA), whale optimization algorithm (WOA), fireworks algorithm (FWA), and quantum particle swarm optimization (QPSO). These methods have been introduced in the past few years and have found very limited or no applications to geophysical exploration problems thus far. We benchmark the algorithms’ results against the particle swarm optimization (PSO), which is a popular and well-established global search method. In particular, we are interested in assessing the exploration and exploitation capabilities of each method as the dimension of the model space increases. First, we test the different algorithms on two multiminima and two convex analytic objective functions. Then, we compare them using the residual statics corrections and 1D elastic full-waveform inversion, which are highly nonlinear geophysical optimization problems. Our results demonstrate that FA, FWA, and WOA are characterized by optimal exploration capabilities because they outperform the other approaches in the case of optimization problems with multiminima objective functions. Differently, QPSO and PSO have good exploitation capabilities because they easily solve ill-conditioned optimizations characterized by a nearly flat valley in the objective function. QPSO, PSO, and WCA offer a good compromise between exploitation and exploration.


2021 ◽  
Vol 15 ◽  
pp. 174830262110084
Author(s):  
Jingsen Liu ◽  
Hongyuan Ji ◽  
Qingqing Liu ◽  
Yu Li

In order to improve the convergence speed and optimization accuracy of the bat algorithm, a bat optimization algorithm with moderate optimal orientation and random perturbation of trend is proposed. The algorithm introduces the nonlinear variation factor into the velocity update formula of the global search stage to maintain a high diversity of bat populations, thereby enhanced the global exploration ability of the algorithm. At the same time, in the local search stage, the position update equation is changed, and a strategy that towards optimal value modestly is used to improve the ability of the algorithm to local search for deep mining. Finally, the adaptive decreasing random perturbation is performed on each bat individual that have been updated in position at each generation, which can improve the ability of the algorithm to jump out of the local extremum, and to balance the early global search extensiveness and the later local search accuracy. The simulating results show that the improved algorithm has a faster optimization speed and higher optimization accuracy.


Fisheries ◽  
2017 ◽  
Vol 42 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Julia M. Lawson
Keyword(s):  

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