The Influence Factor Analysis of Symmetrical Half-Bridge Power Converter through Regression, Rough Set and GM(1,N) Model

Analysis of power converter performance has tended to be engineering-oriented, focusing mainly on voltage stability, output power and efficiency improvement. However, there has been little discussion about the weight relations between these factors. In view of the previous inadequacy, this study employs regression, rough set and GM(1,N) to analyze the relations among the factors that affect the converter, with a symmetrical half-bridge power converter serving as an example. The four related affecting factors, including the current conversion ratio, voltage conversion ratio, power conversion ratio and output efficiency, are firstly analyzed and calculated. The respective relative relations between output efficiency and the other three factors are obtained. This research can be referred to by engineers in their design of symmetrical half-bridge power converters.

Multidimensional Urban Vitality on Streets: Spatial Patterns and Influence Factor Identification Using Multisource Urban Data

Urban vitality is a key indicator for measuring urban development. This topic has been trending in urban planning and sustainable development, and significant progress has been made in measuring single indicators of urban vitality based on parcel or block units. With the continuous development of smart sensing technology, multisource urban data are becoming increasingly abundant. The application of such data to measure the multidimensional urban vitality of street space, reflecting multiple functions of an urban space, can significantly improve the accuracy of urban vitality analyses and promote the construction of people-oriented healthy cities. In this study, streets were taken as the analysis unit, and multisource data such as the trajectories of taxies and shared bicycles, user reviews and cultural facility points of interest (POIs) in Chengdu, a city in southwestern China, were used to identify spatial patterns of urban vitality on streets across social, economic and cultural dimensions. The correlation between the built environment factors and the multidimensional urban vitality on the street was analyzed using a multiple regression model. The spatial distribution of the different dimensions of urban vitality of the street space in Chengdu varies to a certain extent. It is common for areas with high social vitality to have production and life centers nearby. High economic vitality centers are typically found along busy streets with a high concentration of businesses. Areas with high cultural vitality centers tend to be concentrated on the city’s central streets. Land use, transportation, external environment, population and employment are all closely linked to urban vitality on streets. The crowd counting and POI density have the greatest impact on multidimensional urban vitality. The crowd and the level of service facilities profoundly affect social interaction, trade activities and cultural communication. The goodness of fit (R2) of the regression models for social, economic and cultural vitality are 0.590, 0.423 and 0.409, respectively. Using multisource urban data, our findings can help stakeholders better understand the spatial patterns and influencing factors of multidimensional urban vitality on streets and provide sustainable urban planning and development strategies for the future.

PENGARUH INTERNET TERHADAP MOTIVASI DAN MINAT BELAJAR PESERTA DIDIK : SURVEY PADA PESERTA DIDIK KELAS XI IPA DI SMAN 1 CIAMPEL

This study aims to determine whether there is an influence of the internet on learning motivation and whether there is an influence of the internet on the learning interest of students in Class XI IPA at SMAN 1 Ciampel. This research activity was carried out online using the google form application with the address in November 2021. The research subjects were students of SMAN 1 Ciampel and the sample used was class XI IPA class 2020. The research method in this research is descriptive quantitative research method. The instrument used is a questionnaire. Collecting data using 3 instruments, namely, first, the influence of the internet, the second is students' learning motivation and the third is students' interest in learning. The reliability test of the instrument obtained Cronbah's Alpha value of 0.880 for the influence of the internet, 0.915 for learning motivation and 0.862 for interest in learning. The data analysis technique used in this study is a description of the data using the mean while for the influence factor using regression. The results showed that the influence of internet media on students' learning motivation has a very strong relationship and the influence of internet media on students' interest in learning also has a very strong relationship as well. ABSTRAKPenelitian ini bertujuan untuk mengetahui adakah pengaruh internet terhadap motivasi belajar dan adakah pengaruh internet terhadap minat belajar peserta didik Kelas XI IPA di SMAN 1 Ciampel. Kegiatan penelitian ini dilakukan secara online menggunakan bantuan aplikasi google form pada bulan November 2021. Subjek penelitiannya adalah peserta didik SMAN 1 Ciampel dan sampel yang digunakan adalah peserta didik kelas XI IPA angkatan 2020. Metode penelitian pada penelitian ini adalah metode penelitian desktiptif kuantitatif. Instrumen yang digunakan adalah angket. Pengumpulan data menggunakan 3 instrumen yaitu pertama, intrumen pengaruh internet, kedua motivasi belajar peserta didik dan ketiga adalah minat belajar peserta didik. Uji coba reliabilitas instrumen didapatkan nilai Alpha Cronbah sebesar 0,880 untuk pengaruh internet, 0,915 untuk motivasi belajar dan 0,862 untuk minat belajar. Teknik analisis data yang digunakan dalam penelitian ini ialah Deskripsi data menggunakan mean sedangkan untuk faktor pengaruh menggunakan regresi. Hasil penelitian menunjukkan bahwa pengaruh media internet terhadap motivasi belajar peserta didik memiliki hubungan yang sangat kuat serta pengaruh media internet terhadap minat belajar siswa juga memiliki hubungan yang sangat kuat pula.

Opportunities and Challenges for Construction Health and Safety Technologies under the COVID-19 Pandemic in Chinese Construction Projects

The Coronavirus disease 2019 (COVID-19) pandemic has resulted in significant delays and cost overrun in construction projects. The implementation of health and safety (H&S) technologies is one of the most important strategies to alleviate the adverse impacts of COVID-19 on the construction industry and help the industry adapt to the new normal. This study aims to evaluate the adoption of H&S technologies for pandemic management in the construction sector under the COVID-19 pandemic. Semi-structured interviews with eighteen practitioners engaged from construction companies and technology firms were conducted to collect their views on the driving forces and issues of the adoption of H&S technologies for pandemic management in Chinese construction projects. The results reveal that the major H&S technologies used included the health quick response (QR) code system, artificial intelligence (AI)-powered fever monitoring, and site access control system. These technologies were reported to be effective in preventing the spread of the pandemic in workplaces. The findings of the study amplify that the pandemic may serve as an acceleration of the adoption of H&S technologies in the construction sector. Other technologies, such as building information modeling, drones, AI-based safety monitoring, and robotics, however, were seldom used in the studied projects. The interviewees addressed several problems regarding the implementation of these technologies. High costs of technologies, a lack of client support, and disruptions to the normal work process were the main hurdles of the adoption of these technologies. The results indicated that the external influence factor—the COVID-19 pandemic—could considerably drive the use of H&S technologies, whereas the internal influence factors—cost and compatibility of technology—might be the major barriers to technology adoption. To encourage the wider use of H&S technologies in construction, the government is recommended to support the technology transformation by granting financial subsidies for costs involved in innovation adoption. Project owners may consider investing substantially in H&S technologies that can strengthen their resilient and innovative ability to adapt to the post-COVID-19 landscape. The present results will be useful to industry stakeholders and researchers interested in developing H&S technologies for combating the COVID-19 pandemic and future crises.

The Study of Optimization of Flocculation and Destabilization Technology of Waste PEM Drilling Fluid in Bohai Oilfield

In light of the difficulty of solid-liquid separation of waste PEM drilling fluid in the Bohai oilfield, constructing an inorganic-organic flocculation system is proposed and the processing method of destabilization technology is optimized. The biggest influence factor on the flocculation process of PEM drilling fluid was determined by designing an orthogonal test. The flocculation mechanism was researched through single factor optimization, combined with zeta potential and particle size distribution test. The results showed that the most significant factors affecting the flocculation of waste PEM drilling fluid were the dosage of inorganic flocculant CaCl2 and flocculation pH value. When the dosage of inorganic flocculant CaCl2 was 1.2% (w/v), the dosage of organic flocculant SDYJ-2 was 0.05%, the flocculation pH value was 3, and the flocculation time was 5 min, the flocculation technology reached the optimization and then the liquid yield can reach 70.96%. The mechanism of flocculation and destabilization was as follows: the inorganic flocculant of CaCl2 mainly reduced the zeta potential of clay particles through electric neutralization. 1% CaCl2 could reduce the potential mean value of drilling fluid system from -38.1 mV to -32.5 mV, and then decrease the repulsion among suspensions. Through bridging curling and electric neutralization, the organic flocculant of SDYJ-2 can absorb and wrap the clay particles after flocculation destabilization to form a network spatial structure, which made clay particles aggregate into large flocs and particles. D50 can increase by 21.5 times, when the concentration of SDYJ-2 was 0.15%.