Error factors of AC-DC conversion circuits accuracy

Voltage standard source is an important basic instrument in the electrical measurement and testing field, and it has important guarantee significance for many industries. AC voltage standard source is based on AC-DC conversion technology to achieve output function of high precision AC voltage. In order to get a better effect of AC-DC conversion, the three factors—operational amplifier, resistance and diode—that have a greater impact on the accuracy of the rectifier output were taken the research object, and their impacts on the circuit error were analyzed respectively. The output result was compared with the output of full wave precision rectification circuit under ideal state, and the scheme of reducing error in the precision rectifier circuit was summarized, which provides a reference for improving the accuracy of AC-DC conversion in the design of full wave rectifier circuit.

Evolvability in the fossil record

The concept of evolvability—the capacity of a population to produce and maintain evolutionarily relevant variation—has become increasingly prominent in evolutionary biology. Paleontology has a long history of investigating questions of evolvability, but paleontological thinking has tended to neglect recent discussions, because many tools used in the current evolvability literature are challenging to apply to the fossil record. The fundamental difficulty is how to disentangle whether the causes of evolutionary patterns arise from variational properties of traits or lineages rather than being due to selection and ecological success. Despite these obstacles, the fossil record offers unique and growing sources of data that capture evolutionary patterns of sustained duration and significance otherwise inaccessible to evolutionary biologists. Additionally, there exist a variety of strategic possibilities for combining prominent neontological approaches to evolvability with those from paleontology. We illustrate three of these possibilities with quantitative genetics, evolutionary developmental biology, and phylogenetic models of macroevolution. In conclusion, we provide a methodological schema that focuses on the conceptualization, measurement, and testing of hypotheses to motivate and provide guidance for future empirical and theoretical studies of evolvability in the fossil record.

Evolvability and the Fossil Record

The concept of evolvability—the capacity of a population to produce and maintain evolutionarily relevant variation—has become increasingly prominent in evolutionary biology. Although paleontology has a long history of investigating questions of evolvability, often invoking different but allied terminology, the study of evolvability in the fossil record has seemed intrinsically problematic. How can we surmount difficulties in disentangling whether the causes of evolutionary patterns arise from variational properties of traits or lineages rather than due to selection and ecological success? Despite these challenges, the fossil record is unique in offering growing sources of data that span millions of years and therefore capture evolutionary patterns of sustained duration and significance otherwise inaccessible to evolutionary biologists. Additionally, there are a variety of strategic possibilities for combining prominent neontological approaches to evolvability with those from paleontology. We illustrate three of these possibilities with quantitative genetics, evolutionary developmental biology, and phylogenetic models of macroevolution. In conclusion, we provide a methodological schema that focuses on the conceptualization, measurement, and testing of hypotheses to motivate and provide guidance for future empirical and theoretical studies of evolvability in the fossil record.

Identifikasi kecakapan inovasi lembaga riset di Indonesia berbasis dokumen

Introduction. Duplication in inventions produced by research institutions in Indonesia becomes an issue. It is important to map the specialization of the invention in research institutions. This study examines the mapping of the innovation in research institutions in Indonesia. Data Collection Method. This study uses a patent-based technology document analysis method to map the potential of technology. The data used is patent data registered in the Direktorat Jenderal Kekayaan Intelektual (DJKI) database. Data Analysis. Metadata analysis was conducted by using the K-Means Klastering method with R software. Results and Discussions. The findings in the pre-analysis show that when the independent variable involved in the model are very large, the Localized feature selection method can effectively select variables without losing much information. There are 5 dominant technology groups that can be produced by research institutions in Indonesia, namely 1) Technology related to the development of measurement and testing instrument technology; 2) Technologies related to food and food ingredients; and 3) microstructural test equipment / detectors; 4) radar technology; 5) Technology in agriculture. Conclusion. The findings show that there are still overlapping inventions by several research institutions in the same technology cluster. K-means clustering with LFSBSS pre analysis has a clear performance in the technology cluster space.

Review of the Modelling Methods of Series Wound DC Motors

Thanks to technological development and ever-increasing environmental regulations, electric and hybrid vehicles are playing an increasingly important role in road transport. An important part of these vehicles is the electric motor, several different types of which are utilized in modern vehicles. One of these types is the series wound DC motor. In this publication, we review the different modelling methods of the above motor type. On the basis of the models we can perform the simulation in MATLAB/Simulink environment. We also present the technical parameters and characteristics that are needed to run the simulation, and the measurement procedure for determining them. Finally, we present the measurement system we have developed for the measurement and testing the motors.

Pedagogy of New Assessment, Measurement, and Testing Strategies in Higher Education

This chapter investigates correlations between learning theory and outcomes. Based on the hypotheses that in university pedagogy the assessment strategy should be interrelated with desired learning outcomes of the student, it is clear that assessment directly impacts student minds and behavior. Therefore, within the global context of assessment, measurement, and testing strategies, this chapter critically explores novel educational assessment methodology as a response to the following research questions: What are the main issues, controversies, and problems in the educational assessment? What are the most effective solutions for the development of life-long competence through an affordable assessment strategy? This study presents insights into the assessment theory concerning deviations in the acquisition settings between training and testing. It also provides an outlook for the potential of transfer assessment methodologies to metacognitive training of a particular target group.