Abstract
Long-term balancing selection typically leaves narrow footprints of increased genetic diversity, and therefore most detection approaches only achieve optimal performances when sufficiently ...small genomic regions (i.e., windows) are examined. Such methods are sensitive to window sizes and suffer substantial losses in power when windows are large. Here, we employ mixture models to construct a set of five composite likelihood ratio test statistics, which we collectively term B statistics. These statistics are agnostic to window sizes and can operate on diverse forms of input data. Through simulations, we show that they exhibit comparable power to the best-performing current methods, and retain substantially high power regardless of window sizes. They also display considerable robustness to high mutation rates and uneven recombination landscapes, as well as an array of other common confounding scenarios. Moreover, we applied a specific version of the B statistics, termed B2, to a human population-genomic data set and recovered many top candidates from prior studies, including the then-uncharacterized STPG2 and CCDC169–SOHLH2, both of which are related to gamete functions. We further applied B2 on a bonobo population-genomic data set. In addition to the MHC-DQ genes, we uncovered several novel candidate genes, such as KLRD1, involved in viral defense, and SCN9A, associated with pain perception. Finally, we show that our methods can be extended to account for multiallelic balancing selection and integrated the set of statistics into open-source software named BalLeRMix for future applications by the scientific community.
Most existing studies about line balancing problems mainly focus on disassembly and assembly separately, which rarely integrate these two modes into a system. However, as critical activities in the ...remanufacturing field, assembly and disassembly share many similarities, such as working tools and processing sequence. Thus, this paper proposes a multi-objective hybrid production line balancing problem with a fixed number of workstations (HPLBP-FNW) considering disassembly and assembly to optimise cycle time, total cost, and workload smoothness simultaneously. And a novel Pareto-based hybrid genetic simulated annealing algorithm (PB-HGSA) is designed to solve it. In PB-HGSA, the two-point crossover and hybrid mutation operator are proposed to produce potential non-dominated solutions (NDSs). Then, a local search method based on a parallel simulated annealing algorithm is designed for providing a depth search around the NDSs to balance the global and local search ability. Numerical results by comparing PB-HGSA with the well-known algorithms verify the effectiveness of PB-HGSA in solving HPLBP-FNW. Moreover, the managerial insights based on a case study are given to inspire enterprise companies to consider hybrid production line in the remanufacturing process, which is beneficial to reduce the cycle time and total cost and improve the service life of the equipment.
Topological edge-reconstruction occurs in hole-conjugate states of the fractional quantum Hall effect. The frequently studied filling factor, ν = 2/3, was originally proposed to harbor two ...counter-propagating modes: a downstream v = 1 and an upstream v = 1/3. However, charge equilibration between these two modes always led to an observed downstream v = 2/3 charge mode accompanied by an upstream neutral mode. Here, we present an approach to synthetize a v = 2/3 edge mode from its basic counter-propagating charged constituents, allowing a controlled equilibration between the two counter-propagating charge modes. This platform is based on a carefully designed double-quantum-well, which hosts two populated electronic sub-bands (lower and upper), with corresponding filling factors, v
and v
. By separating the 2D plane to two gated intersecting halves, each with different fillings, counter-propagating chiral modes can be formed along the intersection line. Equilibration between these modes can be controlled with the top gates' voltage and the magnetic field.
Abstract
In this paper, we consider methods for generating draws of a binary random variable whose expectation conditional on covariates follows a logistic regression model with known covariate ...coefficients. We examine approximations for finding a “balancing intercept,” that is, a value for the intercept of the logistic model that leads to a desired marginal expectation for the binary random variable. We show that a recently proposed analytical approximation can produce inaccurate results, especially when targeting more extreme marginal expectations or when the linear predictor of the regression model has high variance. We then formulate the balancing intercept as a solution to an integral equation, implement a numerical approximation for solving the equation based on Monte Carlo methods, and show that the approximation works well in practice. Our approach to the basic problem of the balancing intercept provides an example of a broadly applicable strategy for formulating and solving problems that arise in the design of simulation studies used to evaluate or teach epidemiologic methods.
Studies on polymorphisms have been foundational to our understanding of evolution. The presence of different phenotypic morphs is sometimes considered a precursor to speciation in which morphs evolve ...into different species. While speciation should initially reduce genetic variation in daughter versus parental species, a common pattern is the recurrence of the same phenotypic polymorphism in many species of a clade. Despite the ubiquity of these persistent polymorphisms, there is little discussion of their evolutionary origins. How does the genetic variation underpinning such polymorphisms cross speciation boundaries? What selection pressures maintain the morphs in multiple daughter species? Using diverse case studies, we highlight the characteristics of polymorphisms and selection regimes influencing the likelihood of polymorphism retention across species radiations.
The same intraspecific polymorphism is often found in many closely related species.Polymorphism recurrence across species radiations requires both that the genetic variation underpinning the polymorphism and the balancing selection regime persists through speciation.Disassortative mating among morphs facilitates their retention across speciation bottlenecks by increasing the likelihood both of polymorphism inheritance and maintenance.Nonecological, negative frequency-dependent selection is particularly likely to promote polymorphism persistence across species radiations because it increases the probability that the balancing selection operating in the parental species continues to operate in the daughter species even when they differ in their ecology.Rapid species radiations may be particularly prone to recurrent polymorphisms because lost morphs are easily reintroduced through introgression.
•We put forward a novel cost-oriented line balancing problem.•Several properties and special cases of the problem are studied.•We design a memetic algorithm that hybridises these properties with a ...genetic algorithm.•Computational experiments highlight the contributions of each component to the quality of the proposed method.
In order to minimize costs, manufacturing companies have been relying on assembly lines for the mass production of commodity goods. Among other issues, the successful operation of an assembly line requires balancing work among the stations of the line in order to maximize its efficiency, a problem known in the literature as the assembly line balancing problem, ALBP.
In this work, we consider an ALBP in which task assignment and equipment decisions are jointly considered, a problem that has been denoted as the robotic ALBP. Moreover, we focus on the case in which equipment has different costs, leading to a cost-oriented formulation. In order to solve the problem, which we denote as the cost-oriented robotic assembly line balancing problem, cRALBP, a hybrid metaheuristic is proposed. The metaheuristic embeds results obtained for two special cases of the problem within a genetic algorithm in order to obtain a memetic algorithm, applicable to the general problem. An extensive computational experiment shows the advantages of the hybrid approach and how each of the components of the algorithm contributes to the overall ability of the method to obtain good solutions.
•Propose a model-based method for testing, adjusting and balancing (TAB).•Design efficient measuring procedures to obtain data for model identification.•Develop sequential tuning methods to set all ...dampers in proper positions.•Balancing accuracy significantly exceeds the ASHRAE’s standard.•The procedure is non-iterative, simple and easy to perform.
In this paper, an efficient method for testing, adjusting and balancing (TAB) of HVAC air duct system is proposed. The proposed method consists of three steps: 1) Establish the mathematical model for duct network; 2) Take pressure and flow rate measurements in the duct system to identify model parameters; 3) Calculate the balancing damper positions to achieve desired flow rates. The novel measuring procedure collects data efficiently, which makes this method practical. In case of no accurate damper position indicator, sequential damper adjustment according to airflow measurements is also proposed. Simulations and experiments have been conducted to validate the proposed method, where the final flow rates in all terminals match with the desired values with no more than 4.7% relative error in experiments. Comparing with existing TAB methods, the proposed method is 1) faster and more efficient by its non-iterative nature, 2) more accurate in balancing results, 3) easier and simpler to be performed, and 4) using flow meters and pressure sensors only. With these advantages, it is expected that the method will be accepted by HVAC industries.
With the increasing penetration of renewable energy resources and plug-in electric vehicles (PEV) in the smart grid, the problem of phase imbalance in a three-phase distribution system becomes more ...challenging. In this paper, we propose a phase balancing (PB) scheme performed by PEVs. With PB remunerations introduced as financial incentives, PEV owners are encouraged to assist the distribution system operator in reducing the phase imbalance. This is achieved by exploiting the charging flexibility of PEV batteries. We formulate this problem into a non-smooth non-cooperative game, where each PEV owner autonomously minimizes his/her charging cost minus the PB remuneration, considering decisions of other PEV owners. Through transforming this game into a smooth extended one, we are able to solve this challenging problem. Specifically, existence of its Nash equilibrium (NE) is demonstrated, and a distributed algorithm is developed to achieve the NE. Convergence proof of this algorithm is also provided. Simulation results validate our proposed scheme, and illustrate that both PEV owners and the distribution system operator will benefit financially. Moreover, the power quality and system reliability of the distribution network can also be improved.
Assembly optimisation activities occur across development and production stages of manufacturing goods. Assembly Sequence Planning (ASP) and Assembly Line Balancing (ALB) problems are among the ...assembly optimisation. Both of these activities are classified as NP-hard. Several soft computing approaches using different techniques have been developed to solve ASP and ALB. Although these approaches do not guarantee the optimum solution, they have been successfully applied in many ASP and ALB optimisation works. This paper reported the survey on research in ASP and ALB that use soft computing approaches for the past 10 years. To be more specific, only Simple Assembly Line Balancing Problem (SALBP) is considered for ALB. The survey shows that three soft computing algorithms that frequently used to solve ASP and ALB are Genetic Algorithm, Ant Colony Optimisation and Particle Swarm Optimisation. Meanwhile, the research in ASP and ALB is also progressing to the next level by integration of assembly optimisation activities across product development stages.
Harmonics generated by nonlinear critical loads are major anxiety for the industries. A control technique for dynamic voltage restorer (DVR) is described to limit voltage harmonics introduced by ...adjustable speed drive (ASD) in the utility. Moreover, this control technique maintains constant dc-link voltage of ASD during any disturbances occurring at point of common coupling. Mathematical description to limit ASD voltage harmonics and to generate reference dc-link voltage of ASD is illustrated in the dq0 frame. Transistor clamped H-bridge (TCHB) multilevel inverter (MLI) is used as a voltage source inverter of DVR. An enhanced capacitor voltage balancing (ECVB) method for TCHB MLI for the fast dynamic performance of DVR is also discussed. The proposed control technique of DVR to limit ASD voltage harmonics is simulated using MATLAB software. Furthermore, a simulation for DVR protecting ASD during source harmonics, unbalance, sag, and swell is carried out and results of ASD performances are demonstrated. The working of the proposed controller of DVR with ECVB strategy based TCHB is reverified using experimental results. ASD voltage harmonics mitigation and fast dynamic response of ECVB based TCHB are the highlights of this article. The performance of the proposed strategy shows satisfactory results with a less complex control system.
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