In this paper, a predictive speed controller (PSC) based on finite control set model predictive control is developed for electric drives. The large difference between the mechanical and electrical ...time constants necessitates long prediction horizons for a direct PSC (DPSC) strategy to be implemented. Therefore, the computation burden for online solving of the optimization problem critically increases even for low-complexity topologies, whereas the DPSC implementation becomes impossible for high-complexity inverters. Additionally, due to the absence of a PI controller in DPSC methods, stability issues arise; therefore, special care is mandated for eliminating steady-state errors. By using proper weighting of the speed errors, along with the current errors, in the cost function of the proposed PSC, the use of many prediction steps becomes unessential. For considering the current dynamics, a linear controller is incorporated in the control law of developed PSC offering improved system behavior, whereas the consideration of the speed errors allows achieving fast response characteristics. The proposed strategy is experimentally evaluated through examining reference and disturbance step changes of a PMSM drive with the three-level neutral-point clamped inverter. Finally, the proposed controller operation is experimentally compared with a predictive torque and speed control, by considering several performance indices.
Abstract
Gene drives offer the possibility of altering and even suppressing wild populations of countless plant and animal species, and CRISPR technology now provides the technical feasibility of ...engineering them. However, population-suppression gene drives are prone to select resistance, should it arise. Here, we develop mathematical and computational models to identify conditions under which suppression drives will evade resistance, even if resistance is present initially. Previous models assumed resistance is allelic to the drive. We relax this assumption and show that linkage between the resistance and drive loci is critical to the evolution of resistance and that evolution of resistance requires (negative) linkage disequilibrium between the two loci. When the two loci are unlinked or only partially so, a suppression drive that causes limited inviability can evolve to fixation while causing only a minor increase in resistance frequency. Once fixed, the drive allele no longer selects resistance. Our analyses suggest that among gene drives that cause moderate suppression, toxin-antidote systems are less apt to select for resistance than homing drives. Single drives of moderate effect might cause only moderate population suppression, but multiple drives (perhaps delivered sequentially) would allow arbitrary levels of suppression. The most favorable case for evolution of resistance appears to be with suppression homing drives in which resistance is dominant and fully suppresses transmission distortion; partial suppression by resistance heterozygotes or recessive resistance are less prone to resistance evolution. Given that it is now possible to engineer CRISPR-based gene drives capable of circumventing allelic resistance, this design may allow for the engineering of suppression gene drives that are effectively resistance-proof.
The problem of power stabilization in electric drives has been well studied. There exist numbers of approaches around the problem which consider the input power alone and suffer to achieve higher ...performance in power stabilization. To handle this issue, an efficient Drive State Analysis based Electric Drive Control model (DSA-EDCM) is presented in this article. The model monitors the drive state of electric drive at each duty cycle. According to the drive state and its previous conditions like voltage consumption, voltage leak, rpm and torque required, the method performs drive state analysis. The drive state analysis algorithm computes the power required at different conditions by computing Power Support value (PSV). Based on the PSV value, the method selects specific drive according to the input voltage received. Selected drive has been triggered for the cycle to maintain power stability. The proposed model improves the performance of power stability and maximizes the utilization performance.
CRISPR-Cas9-based gene drive systems possess the inherent capacity to spread progressively throughout target populations. Here we describe two self-copying (or active) guide RNA-only genetic ...elements, called e-CHACRs and ERACRs. These elements use Cas9 produced in trans by a gene drive either to inactivate the cas9 transgene (e-CHACRs) or to delete and replace the gene drive (ERACRs). e-CHACRs can be inserted at various genomic locations and carry two or more gRNAs, the first copying the e-CHACR and the second mutating and inactivating the cas9 transgene. Alternatively, ERACRs are inserted at the same genomic location as a gene drive, carrying two gRNAs that cut on either side of the gene drive to excise it. e-CHACRs efficiently inactivate Cas9 and can drive to completion in cage experiments. Similarly, ERACRs, particularly those carrying a recoded cDNA-restoring endogenous gene activity, can drive reliably to fully replace a gene drive. We compare the strengths of these two systems.
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•e-CHACRs can efficiently copy and inactivate Cas9 activity (∼99%)•e-CHACRs spread to 100% prevalence in cage trials and eliminate Cas9 activity•ERACRs often copy but can also damage the target chromosome•ERACRs can efficiently delete and completely replace a gene drive in population cages
Xu et al. describe two genetic systems for neutralizing an active gene drive that efficiently attenuate drive frequency in both pair crosses and cage-population experiments. These neutralization systems either delete the gene drive from the genome (ERACRs) or inactivate the Cas9 protein (e-CHACRs) to halt the gene drive.
Gene drives could allow for control of vector-borne diseases by directly suppressing vector populations or spreading genetic payloads designed to reduce pathogen transmission. Clustered regularly ...interspaced short palindromic repeat (CRISPR) homing gene drives work by cleaving wild-type alleles, which are then converted to drive alleles by homology-directed repair, increasing the frequency of the drive in a population over time. However, resistance alleles can form when end-joining repair takes place in lieu of homology-directed repair. Such alleles cannot be converted to drive alleles, which would eventually halt the spread of a drive through a population. To investigate the effects of natural genetic variation on resistance formation, we developed a CRISPR homing gene drive in
and crossed it into the genetically diverse
Genetic Reference Panel (DGRP) lines, measuring several performance parameters. Most strikingly, resistance allele formation postfertilization in the early embryo ranged from 7 to 79% among lines and averaged 42 ± 18%. We performed a genome-wide association study using our results in the DGRP lines, and found that the resistance and conversion rates were not explained by common alleles of large effect, but instead there were several genetic polymorphisms showing weak association. RNA interference knockdown of several genes containing these polymorphisms confirmed their effect, but the small effect sizes imply that their manipulation would likely yield only modest improvements to the efficacy of gene drives.
Tunable liquid lenses with controllable focal length attract much attention from many researchers due to the unique advantages of strong adjustability, low power consumption, fast response time, and ...easy integration. In the last two decades, tunable liquid lenses have already been applied in machine vision, code scanner cameras, cellphone cameras, webcams, microscopes, mini projectors, AR/VR displays, 3D displays, and so on. There is no doubt that the tunable liquid lenses play an increasingly more important role in the field of optical technology. In this review, the research background and significance of the tunable liquid lenses are introduced. Tunable liquid lenses are systematically qualified according to the driving mechanism, and their current status and latest progress are presented in detail. The existing problems, directions for future research, and current and potential applications of the tunable liquid lenses are also discussed.
Tunable liquid lenses with tunable focal length attract much attention from many researchers due to the unique advantages of strong adjustability, low power consumption, fast response time, and easy integration. This review introduces the research background, classification, driving mechanism, latest progress, limitations, directions for future research, and current and potential applications of the tunable liquid lenses.
Exposure to body-positive imagery plays a positive role in women's body image. However, literature has not examined if this is the case for men too. In this study (N = 207), we examined the impact of ...idealized body and body-positive imagery on both men's and women's body satisfaction and body image concerns. Participants were asked to report their positive and negative mood, body satisfaction, drive for thinness, and drive for muscularity before and after being exposed to either control (landscapes and animals), idealized body, or body-positive imagery. Results showed that women were overall more dissatisfied with their bodies and reported a stronger negative mood and a higher drive for thinness than men. Men, instead, reported a higher drive for muscularity. Exposure to idealized body imagery decreased positive mood and body satisfaction in both men and women. In contrast, exposure to body-positive imagery increased body satisfaction and decreased the drive for thinness in both men and women. Drive for muscularity was not affected by the type of imagery. The findings show that idealized body and body-positive imagery have similar effects on men and women and showcase the importance of considering the effects of body-positivity content for both genders.
•Women reported less body satisfaction and a stronger drive for thinness and men a stronger drive for muscularity.•Exposure to idealized body imagery decreased positive mood and body satisfaction in both men and women.•Exposure to body-positive imagery increased body satisfaction and decreased the drive for thinness in both men and women.•Women were more likely to like body-positive imagery, whereas men preferred control images.•Both men and women were more likely to positively comment on body-positive than the other types of imagery.
Vector-borne diseases, such as dengue, Zika and malaria, are a major cause of morbidity and mortality worldwide. These diseases have proven difficult to control and currently available management ...tools are insufficient to eliminate them in many regions. Gene drives have the potential to revolutionize vector-borne disease control. This suite of technologies has advanced rapidly in recent years as a result of the availability of new, more efficient gene editing technologies. Gene drives can favorably bias the inheritance of a linked disease-refractory gene, which could possibly be exploited (i) to generate a vector population incapable of transmitting disease or (ii) to disrupt an essential gene for viability or fertility, which could eventually eliminate a population. Importantly, gene drives vary in characteristics such as their transmission efficiency, confinability and reversibility, and their potential to develop resistance to the drive mechanism. Here, we discuss recent advancements in the gene drive field, and contrast the benefits and limitations of a variety of technologies, as well as approaches to overcome these limitations. We also discuss the current state of each gene drive technology and the technical considerations that need to be addressed on the pathway to field implementation. While there are still many obstacles to overcome, recent progress has brought us closer than ever before to genetic-based vector modification as a tool to support vector-borne disease elimination efforts worldwide.
Over the last two decades, Model Predictive Control (MPC) has gained popularity in the published research on power electronics. It is argued in the literature that MPC is well-suited for industrial ...variable speed drive (VSD) applications, due to its flexible and multi-objective nature. However, the adoption of MPC by industry has been slow. This paper reviews the VSD control strategies currently accepted by industry. It formulates expectations and determines the existing barriers for using MPC in VSD applications. Following that, the paper proposes a number of novel modifications to enhance the MPC performance and to offer new benefits to industry, compared to the existing solutions. The results of the paper are supported by simulations and validated by experiment.
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