Variable coefficient fractional‐order PID controller and its application to a SEPIC device

The fractional-order proportional–integral–derivative (FOPID) controller has two more parameters than the integer-order proportional–integral–derivative (PID). Such characteristic makes the controller design more flexible and leads to superior performance. This study proposes a variable coefficient FOPID (VCFOPID) with optimal single step parameters, combining discrete synthesis and variable control parameters. The new algorithm is compared with previous FOPID discrete methods via several examples. Since the energy losses of the single-ended primary-inductor converter (SEPIC) cannot be ignored, the standard models are insufficient and a new model is derived using quantum-behaved particle swarm optimisation. The VCFOPID is applied to the SEPIC and both the effectiveness of the controller and the model are verified experimentally.The authors would like to thank the anonymous reviewers for their constructive comments, which greatly improved the quality of this paper. This work was supported by the National Natural Science Funds of China (nos. 61403115 and 11971032).info:eu-repo/semantics/publishedVersio

Cross-sectional investigation and correlation analysis of psychology of college students returning to campus after COVID-19 lockdown lift

ObjectiveTo conduct a large cross-sectional survey of the mental health of college students during the recovery period of the COVID-19 epidemic.MethodsSymptom Checklist 90 (SCL-90) and COVID-19 questionnaire were used to investigate the overall mental health level and cognition of epidemic situation of college students in seven colleges and universities in Shaanxi Province.Results(1) In the recovery period of COVID-19 epidemic, college students still had psychological and somatic symptoms such as obsessive-compulsive disorder, interpersonal sensitivity, anxiety, hostility, and poor appetite or insomnia; (2) female college students, science and engineering college students, freshmen and senior graduates, and some ethnic minority college students were all groups with psychological symptoms; (3) the psychological status of college students was related to their perception of COVID-19 epidemic, and the more knowledge about epidemic prevention and control, the more confident they were in overcoming the epidemic, and the milder the psychological symptoms.ConclusionCollege students still have some mental health problems in the recovery period of COVID-19 epidemic, which should be paid attention to by education authorities and colleges and universities

Effect of Ultrasonic Treatment on Vitis vinifera L. Cell Wall Pectin Components

In order to clarify the content and structural changes of different pectin fractions in grape cell walls under ultrasonic treatment, the grapes were treated with different ultrasonic time and ultrasonic power in this study, and the content of pectin fractions, composition of monosaccharides and structural changes of grape cell walls were analyzed by means of carbazole sulfuric acid method, PMP pre-column derivatization, high-performance liquid gel chromatography , scanning electron microscopy, Fourier transform infrared spectroscopy and circular dichroism. Results showed that the highest and the lowest contents in fresh grape cell walls were alkali-soluble pectin (NSP) and chelate pectin (CSP), respectively, and they were 27.41 mg/g AIR and 8.25 mg/g AIR. The total pectin decreased after ultrasonic treatments, in which the water-soluble pectin (WSP) increased and the CSP and NSP decreased. A total of six monosaccharides were detected in three pectins, and the monosaccharides of different pectin were not the same. The galactose and arabinose were high in WSP, the glucuronic acid was the most abundant of CSP and the rhamnose were the highest in NSP. After ultrasonic treatment, the contents of monosaccharides decreased, while the composition did not change, and the main chain structure of pectin was no change, but the linear structure and the degree of branch chain were changed. With the increase of ultrasonic times and powers, the molecular weight of different pectins declined gradually. And in the microstructure showed a more loose morphology. In addition, ultrasonic treatment had an effect on the structure and chain conformation of CSP and NSP, which made their maximum response values shift, and the effect of ultrasonic power was more significant. In conclusion, ultrasonic treatment could reduce the pectin and monosaccharide contents in grape cell walls, and affect the molecular linear structure and molecular chain conformation of pectin. These results can provide theoretical basis for the quality change of grape products under ultrasonic treatment

Grain engineering of Sb2S3 thin films to enable efficient planar solar cells with high open-circuit voltage

Sb2S3 is a promising environmentally friendly semiconductor for high performance solar cells. But, like many other polycrystalline materials, Sb2S3 is limited by nonradiative recombination and carrier scattering by grain boundaries (GBs). This work shows how the GB density in Sb2S3 films can be significantly reduced from 1068 ± 40 to 327 ± 23 nm µm−2 by incorporating an appropriate amount of Ce3+ into the precursor solution for Sb2S3 deposition. Through extensive characterization of structural, morphological, and optoelectronic properties, complemented with computations, it is revealed that a critical factor is the formation of an ultrathin Ce2S3 layer at the CdS/Sb2S3 interface, which can reduce the interfacial energy and increase the adhesion work between Sb2S3 and the substrate to encourage heterogeneous nucleation of Sb2S3, as well as promote lateral grain growth. Through reductions in nonradiative recombination at GBs and/or the CdS/Sb2S3 heterointerface, as well as improved charge-carrier transport properties at the heterojunction, this work achieves high performance Sb2S3 solar cells with a power conversion efficiency reaching 7.66%. An impressive open-circuit voltage (VOC) of 796 mV is achieved, which is the highest reported thus far for Sb2S3 solar cells. This work provides a strategy to simultaneously regulate the nucleation and growth of Sb2S3 absorber films for enhanced device performance

Grain engineering of Sb2S3 thin films to enable efficient planar solar cells with high open-circuit voltage

Sb2S3 is a promising environmentally friendly semiconductor for high performance solar cells. But, like many other polycrystalline materials, Sb2S3 is limited by nonradiative recombination and carrier scattering by grain boundaries (GBs). This work shows how the GB density in Sb2S3 films can be significantly reduced from 1068 ± 40 to 327 ± 23 nm µm−2 by incorporating an appropriate amount of Ce3+ into the precursor solution for Sb2S3 deposition. Through extensive characterization of structural, morphological, and optoelectronic properties, complemented with computations, it is revealed that a critical factor is the formation of an ultrathin Ce2S3 layer at the CdS/Sb2S3 interface, which can reduce the interfacial energy and increase the adhesion work between Sb2S3 and the substrate to encourage heterogeneous nucleation of Sb2S3, as well as promote lateral grain growth. Through reductions in nonradiative recombination at GBs and/or the CdS/Sb2S3 heterointerface, as well as improved charge-carrier transport properties at the heterojunction, this work achieves high performance Sb2S3 solar cells with a power conversion efficiency reaching 7.66%. An impressive open-circuit voltage (VOC) of 796 mV is achieved, which is the highest reported thus far for Sb2S3 solar cells. This work provides a strategy to simultaneously regulate the nucleation and growth of Sb2S3 absorber films for enhanced device performance

Age attribution of coal bearing strata in Beishan Basin Group, Ganmeng area

A large number of coal bearing strata are developed in Beishan Basin Group of Ganmeng area.However, due to the complexity of tectonic evolution, lack of seismic, drilling and related paleontological data, the age of coal bearing strata has been controversial, and the potential of resources is not clear.On the basis of summarizing the previous research results, taking paleontology chronology as the starting point, combining the characteristics of rock assemblage, coal industrial characteristics, seismic data, outcrop data and other evidence, the age attribution of coal bearing strata in Beishan Basin Group is studied.According to the analysis of sporopollen paleontology, coal petrology industrial characteristics and stratigraphic contact relationship, it is considered that each basin of Beishan Basin Group has developed a set of coal bearing series, but the age of this coal bearing system is not the same.Some are Jurassic and some are Cretaceous, but the possibility of Triassic or Permian is ruled out.Only the coal bearing strata in the southern part of Zhongkouzi Basin in the southernmost part of Beishan Basin Group and the eastern part of Heiyingshan Basin in the northernmost part of the basins group are Jurassic, and the coal bearing rock series of other sub basins belong to Cretaceous.The coal bearing strata in Zhongkouzi Basin in the southern part of the basins group show a "North-South difference" consistent with the structure features.The age of the exposed coal bearing strata in the south is Middle Jurassic, and that in the north is Cretaceous.The classification of the coal bearing series provides a basis for further determining the resource potential of Beishan Basin Group, and provides a reference for the study of the prototype basin restoration and tectonic evolution of the coal bearing series in the Beishan Basin Group

Improved genetic distance-based spatial deployment can effectively minimize inbreeding in seed orchard

Background: Inbreeding in seed orchards is expected to increase with the advancement of breeding cycles, which results in the delivery of crops with suboptimal genetic gain, reduced genetic diversity, and lower seed set. Here, a genetic distance-dependent method for clonal spatial deployment in seed orchards was developed and demonstrated, which reduced the inbreeding levels. The method’s main evaluation parameter of inbreeding is the genetic distance among individuals and the deployment method used an improved adaptive parallel genetic algorithm (IAPGA) based on Python language. Using inbreeding-prone Chinese Mongolian pine breeding population material originating from a single natural population, the proposed method was compared to a traditional orchard design and a distance-based design; namely, complete randomized block (RCB) and optimum neighborhood (ONA) designs, respectively. Results: With the advancement of selective breeding cycles, group separation among orchard related individuals is expected to increase. Based on the genetic distance among individuals, the IAPGA design was superior in significantly reducing the inbreeding level as compared to the two existing designs, confirming its suitability to advanced-generation orchards where relatedness among parents is common. In the 1st, 2nd, and mixed generations clonal deployment schemes, the IAPGA design produced lower inbreeding with 87.22%, 81.49%, and 87.23% of RCB, and 92.78%, 91.30%, and 91.67% of ONA designs, respectively. Conclusions: The IAPGA clonal deployment proposed in this study has the obvious advantage of controlling inbreeding, and it is expected to be used in clonal deployment in seed orchards on a large-scale. Further studies are needed to focus on the actual states of pollen dispersal and mating in seed orchards, and more assumptions should be taken into account for the optimized deployment method.Forestry, Faculty ofNon UBCForest and Conservation Sciences, Department ofReviewedFacult