Soft-switching High Frequency AC Link Buck-Boost DC-DC Converters

AC link universal power converters are a relatively new class of power converters with numerous advantages. The reason they get the universal power converters name is that inputs and outputs of these converters can be either dc or ac; therefore, they can be configured as dc-dc, dc-ac, ac-dc, or ac-ac. Also, input and output can be multi-phase or single-phase. The ac link universal converters can be widely and efficiently used in numerous applications from small electronics device to high power renewable energy systems, such as solar and wind power generation. The ac link universal converters can benefit from soft-switching with a small modification in the configuration and control. Switches in the modified configuration will benefit from zero-voltage turn on and soft turn off. Compared with hard-switching converters, power dissipation is greatly reduced in soft-switching ac link converters. In this thesis, the dc-dc ac link universal converter will be studied in detail. At the same time, some modified configurations that require fewer switches are introduced in this thesis. Soft-switching ac-link universal converter have a relatively complex control algorithm; therefore, in most cases digital control methods are used in these converters. Digital control can be implemented through microcontrollers or FPGAs. Use of microcontrollers limits the link frequency due to long microcontroller execution time and delays. FPGA is faster; however, it is more expensive compared with analog controllers. In this thesis, two new control methods that can be implemented by analog circuits are proposed for regulating the voltage in these converters. One of these methods uses PI controller along with PWM; thus switching frequency is fixed. The other control method uses a PI controller for generating the reference of the link peak current, and operates with variable switching frequency. Control schemes proposed in this thesis are simplified, and can be implemented through analog circuit

Lipid composition and abundance in the reproductive and alimentary tracts of female Haemonchus contortus

The full list of identified lipid species in the Haemonchus contortus lipidome.</p

Graph-Assisted Inverse Regression for Count Data and Its Application to Sequencing Data

Multivariate count data, such as sequencing reads in genomics, are often connected to a clinical phenotype of interest. We develop a flexible framework for dimension reduction in regression, with predictors that are correlated counts, by modeling the conditional distribution of the predictors, given the response, using a pairwise Poisson graphical model. This new framework, called network-based inverse regression for counts, allows us to derive a sufficient reduction of the predictors, while adjusting for the dependence structure among them. We propose a regularized criterion for estimating both the reduction structure and the network structure. The estimation algorithm can be implemented efficiently on a parallel computer. We also introduce an adaptive version and a sparse variant of the proposed procedure. The methods are evaluated on simulated data and are applied to a gut microbiome sequencing dataset. Supplementary materials for this article are available online.</p

A revisit to two-way factorial ANOVA with mixed effects and interactions

Two mixed models exist in analysis of two-way factorial ANOVA with mixed effects and interactions: the constrained and unconstrained models. The constrained model is unfavored because there is no convincing rationale for the enforced constraints on its random interactions and a lack of clear interpretation about its variance components. The purpose of this study is to further explore the relationship between these two models. We reveal some nice features of the constrained model on partition of the responsive variance. An alternative formulation of ANOVA that follows from this exploration is also presented.</p

China's Energy Transition: Pathways for Low Carbon Development

No description supplie

Significant Efficacy of Desiccants in the Synthesis of Distyryl Ketones/Chalcones Bearing Phenolic Hydroxyl Groups

Complicated catalysts or rigorous synthesis methods are commonly necessary for the synthesis of distyryl ketones and chalcones bearing phenolic hydroxyl groups. Boron trifluoride etherate can serve as a type of high-efficiency catalyst for the synthesis of those products, but it will be quickly deactivated by the produced water during the reactions. However, the addition of an excessive amount of this catalyst will lead to serious side reactions and waste. In this work, by promptly removing the water produced from the reactions with the aid of desiccants, the products distyryl ketone and chalcone bearing phenolic hydroxyl groups are synthesized in high yield, as exemplified by the synthesis of 1,5-bis­(4-hydroxyphenyl) penta-1,4-dien-3-one and 1,3-bis (4-hydroxyphenyl) prop-2-en-1-one, each representing very typical types of phenolic hydroxyl groups containing distyryl ketones and chalcones. The effects of desiccant species and dosages have been studied. On this basis, the species of desiccant is optimized as CaCl2, and then its proper dosage and the corresponding optimal reaction conditions are achieved

Precision values of link prediction indices on example networks.

The order of the networks is organized according to their increasing assortative coefficient (from negative to positive), and values in brackets under the network names are the coefficient of each network.</p

Illustration of the theoretical mode.

Currently, countries worldwide are embracing digital strategies, enabling enterprises to utilize digital technology, digital supply chains, blockchain, and additional digital measures to increase their competitiveness. This paper analyzed the correlation between the digital transformation of manufacturing export enterprises and their business and export performance, focusing on China’s manufacturing export enterprises through empirical analysis. The study investigated the influence of digital transformation on enterprise performance. Using the Resource Based View theory and Trade theory, hypotheses were proposed and regression models were developed to analyze a sample of 1007 enterprises listed on the Shanghai and Shenzhen Stock markets from 2012 to 2019. The study conducted regression analysis, intermediate effect test, robustness test, stage lag, and heterogeneity analysis. The study found that (1) Manufacturing export enterprises listed in the stock market implemented digital transformation, leading to a significant positive impact on their overall performance. (2) Digital transformation led to cost reduction, improved R&D intensity, and enhanced human resources, among other benefits for enterprise performance. (3) According to the fractal analysis, non-state-owned enterprises exhibited more favorable effects on enterprise performance, and the digital transformation of manufacturing export companies in developed regions had a more significant impact on their performance. Finally, the study’s empirical results yielded pertinent proposals for digital transformation.</div

Results of mediating effect test and analysis of enterprise performance in the digital transformation degree of manufacturing enterprises.

Results of mediating effect test and analysis of enterprise performance in the digital transformation degree of manufacturing enterprises.</p

Results of empirical analysis of digital transformation of manufacturing export enterprises on enterprise performance.

Results of empirical analysis of digital transformation of manufacturing export enterprises on enterprise performance.</p