The purpose of this paper is to provide a feasible method to solve the zenith pass problem that can occur when the inter‐satellite linkage antenna of the user satellite is tracing…
Abstract
Purpose
The purpose of this paper is to provide a feasible method to solve the zenith pass problem that can occur when the inter‐satellite linkage antenna of the user satellite is tracing TDRS. The antenna uses the elevation‐over‐azimuth architecture.
Design/methodology/approach
The movement laws of the inter‐satellite linkage can be obtained based on the orbit predictions of the user satellite and TDRS. According to the movement laws, the zenith pass moments and blindness zones are found. The trajectory preprocessor is provided to design a command trajectory for driving the axis of the tilting mechanism.
Findings
In the worst situation, the blindness zone can appear once every half day. Three special orbit altitude values are obtained. When the user satellite picks one of them as its orbit altitude, the blindness zone may be avoided forever. The zenith pass tracing strategies based on the mechanical tilting method have been designed.
Research limitations/implications
This method obtains the stable tracking during the zenith pass course by changing the hardware structure of the antenna. It is too expensive and can influence the pointing precision of the antenna.
Practical implications
The research can help the engineers analyze and solve the zenith pass problem of the antenna.
Originality/value
This paper studies the zenith pass problem that can occur when the inter‐satellite linkage antenna of the user satellite is tracing TDRS and provides a solving method.
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Keywords
Kun Lu, Xueyuan Deng and Xiaoqiang Zhai
The operational carbon simulation in the building design stage is significant to life cycle carbon emissions. However, this process is challenging to reuse multi-source building…
Abstract
Purpose
The operational carbon simulation in the building design stage is significant to life cycle carbon emissions. However, this process is challenging to reuse multi-source building information modeling (BIM) under different information availability. Thus, this study suggests an OpenBIM-based method for operational carbon simulation to integrate heterogeneous BIM models with different data accuracy, which can be applied across various stages of building design.
Design/methodology/approach
This study suggests a three-step method for operational carbon simulation using industry foundation classes (IFC). This method uses IfcSpace as the fundamental unit for limited data while using IfcDistributionElement for abundant data. Additionally, a case study proves the method's accuracy and efficiency by comparing it with existing tools.
Findings
Although the information availability is different, the simulation results of operational carbon are similar between schematic design and construction document design, with 1816.4 tCO2e/year and 1962.4 tCO2e/year, respectively. Furthermore, the case study shows a 16.9% carbon reduction through scheme optimization.
Originality/value
This study offers an approach that can directly utilize the multi-source heterogeneous BIM models to save time and reduce labor consumption. Using the space and the element as calculation units extends the simulation theory for evolving information accessibility across design stages.
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Satanu Ghosh and Kun Lu
The purpose of this paper is to present a preliminary work on extracting band gap information of materials from academic papers. With increasing demand for renewable energy, band…
Abstract
Purpose
The purpose of this paper is to present a preliminary work on extracting band gap information of materials from academic papers. With increasing demand for renewable energy, band gap information will help material scientists design and implement novel photovoltaic (PV) cells.
Design/methodology/approach
The authors collected 1.44 million titles and abstracts of scholarly articles related to materials science, and then filtered the collection to 11,939 articles that potentially contain relevant information about materials and their band gap values. ChemDataExtractor was extended to extract information about PV materials and their band gap information. Evaluation was performed on randomly sampled information records of 415 papers.
Findings
The findings of this study show that the current system is able to correctly extract information for 51.32% articles, with partially correct extraction for 36.62% articles and incorrect for 12.04%. The authors have also identified the errors belonging to three main categories pertaining to chemical entity identification, band gap information and interdependency resolution. Future work will focus on addressing these errors to improve the performance of the system.
Originality/value
The authors did not find any literature to date on band gap information extraction from academic text using automated methods. This work is unique and original. Band gap information is of importance to materials scientists in applications such as solar cells, light emitting diodes and laser diodes.
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Keywords
WeChat official account (WCOA) is an emerging and important platform for academic library services, which greatly accelerates the development of this field. This article aims to…
Abstract
Purpose
WeChat official account (WCOA) is an emerging and important platform for academic library services, which greatly accelerates the development of this field. This article aims to identify key evaluation indicators for users' satisfaction of the Academic Library WeChat Official Account (ALWCOA) as a reference for future improvements.
Design/methodology/approach
Based on the updated DeLone and McLean (D&M)’s model and Delphi method, an evaluation system of ALWCOA satisfaction was constructed. Then 212 university students were recruited to fill out a questionnaire on evaluation indicators. The grey relational analysis (GRA) and Pareto's principle were employed to analyze the questionnaire and select key evaluation indicators.
Findings
An ALWCOA service satisfaction evaluation system with three evaluation dimensions and 15 evaluation indicators was constructed, and three key evaluation indicators were identified, including service responsiveness, information timeliness and system security.
Practical implications
This article provides a strategy for assessing ALWCOA service satisfaction, as well as insights for improving of ALWCOA service. Specifically, academic libraries should pay more attention to improving service responsiveness, information timeliness and system security.
Originality/value
This article innovatively applied the updated D&M model in academic library service. Additionally, it facilitates the development of research fields, such as academic library services, microservices and user service evaluation, and provides a case study to better understand the WCOA.
Details
Keywords
Zeng Wu, Wei Ma, Hong-xiu Xiao and Jing-kun Zhang
Fastener technology is one of the key technologies of the ballastless track structure, and the spring strip is the key component to realize the fastener function. Based on the…
Abstract
Purpose
Fastener technology is one of the key technologies of the ballastless track structure, and the spring strip is the key component to realize the fastener function. Based on the fatigue test of the WJ-7 type fastener of the ballastless track in China, it is concluded that the fatigue damage of an elastic strip is the main reason for the decline of service performance of the fastener. The purpose of this paper is to discuss the fatigue life of the fastener.
Design/methodology/approach
First, a DH3818 static strain tester is used to measure the static strain signal in the elastic strip fatigue test, and then the fatigue limit of the WJ-7 elastic strip is calculated. Finally, the fatigue life of the fastener strip is estimated.
Findings
The findings of the paper are as follows: first, the lowest fatigue life with a survival rate of 99 percent should be taken as a reference for the service times of WJ-7; second, the fatigue life of the modified formula found to be short under the same stress amplitude.
Originality/value
The fatigue test is processed by the authors and the results of elastic strip are obtained based on the test. Meanwhile, the corresponding limit value of the fatigue stress amplitude is calculated based on the tested results.
Details
Keywords
Cong Liu, Baohong Tong, Guotao Zhang, Wei Wang, Kun Liu and Peimin Xu
This paper aims to investigate the influence of oil–air lubrication flow behavior on point contact sliding wear characteristics.
Abstract
Purpose
This paper aims to investigate the influence of oil–air lubrication flow behavior on point contact sliding wear characteristics.
Design/methodology/approach
Oil–air lubrication equations between point contact counterparts were established on the basis of volume of fluid model. The effects of oil supply and injection azimuth on oil-phase volume fraction and its pressure distribution were simulated with commercial software Fluent. Characteristics of point contact sliding wear were then tested with an MFT-3000 friction tester under oil–air lubrication condition. The influence of flow behavior on wear characteristic was investigated combined with numerical and experimental results. The wear mechanism was revealed using SEM, EDS and ferrography.
Findings
When air supply speed is constant, the oil-phase volume fraction increases with the increase in oil supply, which helps form continuous oil film and decrease the sliding wear evidently. The injection angle and distance considerably influence the oil–air flow behavior. When injecting at a certain distance and angle, the oil-phase volume fraction reaches its maximum, and the abrasion loss is minimal. Under the test conditions in this study, abrasive particles are mainly debris and a few spiral cuttings. The wear mechanism is abrasive wear.
Originality/value
The influence of the behavior of oil–air lubrication flow on the characteristic of point contact sliding wear is analyzed. This work provides guidance for the application of oil–air lubrication technology in point contact friction pairs.
Details
Keywords
Qiuchen Zhao, Xue Li, Junchao Hu, Yuehui Jiang, Kun Yang and Qingyuan Wang
The purpose of this paper is to determine the ultra-high cycle fatigue behavior and ultra-slow crack propagation behavior of selective laser melting (SLM) AlSi7Mg alloy under…
Abstract
Purpose
The purpose of this paper is to determine the ultra-high cycle fatigue behavior and ultra-slow crack propagation behavior of selective laser melting (SLM) AlSi7Mg alloy under as-built conditions.
Design/methodology/approach
Constant amplitude and two-step variable amplitude fatigue tests were carried out using ultrasonic fatigue equipment. The fracture surface of the failure specimen was quantitatively analyzed by scanning electron microscope (SEM).
Findings
The results show that the competition of surface and interior crack initiation modes leads to a duplex S–N curve. Both manufacturing defects (such as the lack of fusion) and inclusions can act as initially fatal fatigue microcracks, and the fatigue sensitivity level decreases with the location, size and type of the maximum defects.
Originality/value
The research results play a certain role in understanding the ultra-high cycle fatigue behavior of additive manufacturing aluminum alloys. It can provide reference for improving the process parameters of SLM technology.
Details
Keywords
Sabina Alkire and Yangyang Shen
Most poverty research has explored monetary poverty. This chapter presents and analyzes the global multidimensional poverty index (MPI) estimations for China. Using China Family…
Abstract
Most poverty research has explored monetary poverty. This chapter presents and analyzes the global multidimensional poverty index (MPI) estimations for China. Using China Family Panel Studies (CFPS), we find China’s global MPI was 0.035 in 2010 and decreased significantly to 0.017 in 2014. The dimensional composition of MPI suggests that nutrition, education, safe drinking water, and cooking fuel contribute most to overall non-monetary poverty in China. Such analysis is also applied to subgroups, including geographic areas (rural/urban, east/central/west, provinces), as well as social characteristics such as gender of the household heads, age, education level, marital status, household size, migration status, ethnicity, and religion. We find the level and composition of poverty differs significantly across certain subgroups. We also find high levels of mismatch between monetary and multidimensional poverty at the household level, which highlights the importance of using both complementary measures to track progress in eradicating poverty.
Details
Keywords
Xinhui He, Kun Huang, Guihao Ran, Xiaobiao Mao, Qin Hu, Zhennan Lin, Shuangquan Ran and Tao Hu
This study aims to improve the sensitivity of magnetic detection. In this article, a multi-frequency modulation technique is used to increase the magnetic detection sensitivity of…
Abstract
Purpose
This study aims to improve the sensitivity of magnetic detection. In this article, a multi-frequency modulation technique is used to increase the magnetic detection sensitivity of diamond nitrogen vacancy (NV) centers sensors.
Design/methodology/approach
In the field of magnetic detection, NV centers have corresponding advantages due to their unique long coherence property at room temperature. The important indicators for NV centers magnetometers are the magnetic detection sensitivity of the NV centers and the integration of the magnetometer. To solve this problem, the authors propose a multi-frequency modulated magnetic detection technique, using an integrated probe as well as a lock-in amplifier for the double enhancement of sensitivity as well as integration.
Findings
The following results can be obtained by processing and calculating the experimental data with an integrated lock-in amplifier circuit with an area of 27.50 cm2 and a probe volume of 3.12 cm3. The multi-frequency modulation technique was used to increase the magnetic detection sensitivity of the NV centers from 8.59 nT/Hz1 / 2–2.42 nT/Hz1 / 2.
Research limitations/implications
The authors propose a signal modulation technique with an integrated design, which achieves an improvement in the sensitivity of the sensor’s magnetic detection through practical testing.
Originality/value
The authors propose a signal modulation technique with an integrated design, which achieves an improvement in the sensitivity of the sensor’s magnetic detection through practical testing. This technique provides new research solution for the subsequent improvement of the magnetic detection sensitivity.
Details
Keywords
Lei Li, Anrunze Li, Xue Song, Xinran Li, Kun Huang and Edwin Mouda Ye
As academic social Q&A networking websites become more popular, scholars are increasingly using them to meet their information needs by asking academic questions. However…
Abstract
Purpose
As academic social Q&A networking websites become more popular, scholars are increasingly using them to meet their information needs by asking academic questions. However, compared with other types of social media, scholars are less active on these sites, resulting in a lower response quantity for some questions. This paper explores the factors that help explain how to ask questions that generate more responses and examines the impact of different disciplines on response quantity.
Design/methodology/approach
The study examines 1,968 questions in five disciplines on the academic social Q&A platform ResearchGate Q&A and explores how the linguistic characteristics of these questions affect the number of responses. It uses a range of methods to statistically analyze the relationship between these linguistic characteristics and the number of responses, and conducts comparisons between disciplines.
Findings
The findings indicate that some linguistic characteristics, such as sadness, positive emotion and second-person pronouns, have a positive effect on response quantity; conversely, a high level of function words and first-person pronouns has a negative effect. However, the impacts of these linguistic characteristics vary across disciplines.
Originality/value
This study provides support for academic social Q&A platforms to assist scholars in asking richer questions that are likely to generate more answers across disciplines, thereby promoting improved academic communication among scholars.