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5461.Action Research on Project-based Learning and Contest-based Learning in Higher Education


Source:Proceedings of the 2021 International e-Engineering Education Services Conference, e-Engineering 2021,2021,Vol.

Abstract:Two action research projects on project-based learning and contest-based learning were conducted in teaching practice based on two specific modules in higher education. It is found that project-based learning with a well-designed project and properly delivered module contents can help students effectively achieve the learning outcomes, and contest-based learning is validated as an effective learning approach that contributes to improving students' learning motivation and performance.





5463.Optimal Design Strategy of a Solar Reflector Combining Photovoltaic Panels to Improve Electricity Output: A Case Study in Calgary, Canada

Author:Kim, MK;Abdulkadir, KO;Liu, JY;Choi, JH;Wen, HQ


Abstract:This study explores the combination of photovoltaic (PV) panels with a reflector mounted on a building to improve electricity generation. Globally, PV panels have been widely used as a renewable energy technology. In order to obtain more solar irradiance and improve electricity output, this study presents an advanced strategy of a reflector combining PV panels mounted on a building in Calgary, Canada. Based on an experimental database of solar irradiances, the simulation presents an optimal shape designed and tilt angles of the reflector and consequently improves solar radiation gain and electricity outputs. Polished aluminum is selected as the reflector material, and the shape and angle are designed to minimize the interruption of direct solar radiation. The numerical approach demonstrates the improvement in performance using a PV panel tilted at 30 degrees, 45 degrees, 60 degrees, and 75 degrees and a reflector, tilted at 15.5 degrees or allowed to be tilted flexibly. A reflector tilted at 15.5 degrees can improve solar radiation gains, of the panel, by nearly 5.5-9.2%% at lower tilt angles and 14.1-21.1%% at higher tilt angles. Furthermore, the flexibly adjusted reflector can improve solar radiation gains on the PV panel, by nearly 12-15.6%% at lower tilt angles and 20-26.5%% at higher tilt angles. A reflector tilted at 15.5 degrees improves the panel's output electricity on average by 4-8%% with the PV panel tilted at 30 degrees and 45 degrees respectively and 12-19%% with the PV panel tilted at 60 degrees and 75 degrees, annually. Moreover, a reflector that can be flexibly tilted improves electricity output on average by 9-12%% with the PV panel tilted at 30 degrees and 45 degrees and 17-23%% with the PV panel tilted at 60 degrees and 75 degrees. Therefore, the utilization of a reflector improves the performance of the PV panel while incurring a relatively low cost.

5464.Adaptive Eco-Driving Strategy and Feasibility Analysis for Electric Trains With Onboard Energy Storage Devices

Author:Wu, CX;Xu, B;Lu, SF;Xue, F;Jiang, L;Chen, MW


Abstract:With the rapid progress in railway electrification and energy storage technologies, onboard energy storage devices (OESDs) have been widely utilized in modern railway systems to reduce energy consumption. This article aims to develop the optimal driving strategy of electric trains with three popular types of energy storage devices, namely supercapacitors, flywheels, and Li-ion batteries, as the OESD to minimize the net energy consumption. With the given OESD investment cost, the dynamic power limits of different types of OESDs are fully considered to optimize the dynamic discharge/charge behavior of the OESD in the train operation. The case studies investigate the train operation on fully electrified railways, discontinuously electrified railways, and catenary-free railways, showing that the optimal eco-driving strategy of the train and discharge/charge behavior of the OESD is significantly different for a different type of OESDs. The obtained train speed, OESDs' state of energy (SOE), power profiles, and energy-saving potential for each type of OESDs under various scenarios are compared comprehensively, and the results also reveal that the flywheel has the best performance for its energy-saving rate ranging from 0.15 %%/k$ to 0.86 %%/k$, while a Li-ion battery is observed with the weakest performance with the energy-saving rate being only 0.01 %%/k$-0.26 %%/k$. The error rate analysis also confirms a satisfactory modeling accuracy of the proposed method.

5465.Can landscape level semi-natural habitat compensate for pollinator biodiversity loss due to farmland consolidation?

Author:Shi, XY;Xiao, HJ;Luo, SD;Hodgson, JA;Bianchi, FJJA;He, HM;van der Werf, W;Zou, Y


Abstract:Traditional farming landscapes in China consist of small irregular fields with an intimately interspersed seminatural habitat network of field margins, but are increasingly converted into consolidated ones that consist of standardized fields with reduced areas of field margins and other semi-natural habitat. It is unclear how such farmland consolidation influences pollinator communities, and if there is a negative effect, whether this effect is mitigated by semi-natural habitat present in the wider landscape. We compared the diversity and abundance of wild pollinators in oilseed rape fields that were embedded in landscapes that consisted either of traditional or consolidated farmland. The landscapes spanned a range of semi-natural habitat area from 10%% to 73%% at a scale of one km radius in Jiangxi Province, China. Pollinators were sampled using pan traps during two years (2015 and 2019). Results showed that pollinator diversity was positively associated with the proportion of semi-natural habitat in both traditional and consolidated farming landscapes, but was higher in traditional farming landscapes. In both years, there was no difference in pollinator abundance between landscapes with traditional and consolidated fields. The results indicate that the network of field margins in traditional farmland supports a diverse pollinator community, and that land consolidation has equivalent effects on pollinator diversity as substantial decreases in semi-natural habitat in the wider landscape. The role of semi-natural habitat in supporting farmland biodiversity and its associated services needs therefore to be considered in plans for farmland consolidation.

5466.MetaTX: deciphering the distribution of mRNA-related features in the presence of isoform ambiguity, with applications in epitranscriptome analysis

Author:Wang, Y;Chen, KQ;Wei, Z;Coenen, F;Su, JL;Meng, J


Abstract:Motivation: The distribution of biological features strongly indicates their functional relevance. Compared to DNA-related features, deciphering the distribution of mRNA-related features is non-trivial due to the existence of isoform ambiguity and compositional diversity of mRNAs. Results: We propose here a rigorous statistical framework, MetaTX, for deciphering the distribution of mRNA-related features. Through a standardized mRNA model, MetaTX firstly unifies various mRNA transcripts of diverse compositions, and then corrects the isoform ambiguity by incorporating the overall distribution pattern of the features through an EM algorithm. MetaTX was tested on both simulated and real data. Results suggested that MetaTX substantially outperformed existing direct methods on simulated datasets, and that a more informative distribution pattern was produced for all the three datasets tested, which contain N-6-Methyladenosine sites generated by different technologies. MetaTX should make a useful tool for studying the distribution and functions of mRNA-related biological features, especially for mRNA modifications such as N-6-Methyladenosine.

5467.Minimum-Current-Stress Scheme of Three-Level Dual-Active-Bridge DC-DC Converters With the Particle Swarm Optimization

Author:Wang, Y;Wen, HQ;Zhu, YX;Shi, HC;Bu, QL;Hu, YH;Yang, Y


Abstract:Current stress is essential for the reliability of power switching devices, especially for high-voltage applications, such as three-level NPC-based dual-active-bridge (3LNPC-DAB) converters. With the conventional single phase shift (SPS) control, the current stress of power devices in 3LNPC-DAB converters is high, which not only affects the conversion efficiency for a wide operating range but also endangers the power devices, which is harmful for the healthy operation of 3LNPC-DAB converters. To solve this problem, this article proposes a minimum-current-stress scheme using particle swarm optimization (PSO) strategy with the aim to reduce the current stress and improve the efficiency of 3LNPC-DAB converters. Different from SPS, two phase shift variables are adopted in the proposed algorithm: one is set between the primary and secondary bridges, and the other is set within the same bridge. Thus, not only the control flexibility is expanded, but also main performance indexes, such as the transmission power, the current stress of each switch, and the efficiency for the whole operating range, are improved. Moreover, the PSO strategy requires fewer parameters to adjust, less computational burden, and faster convergence speed, which simplifies the theoretical calculation and the practical implementation. Finally, the main experimental results for various operating conditions are provided to validate the proposed scheme.

5468.On the use of large interactive displays to support collaborative engagement and visual exploratory tasks

Author:Chen,Lei;Liang,Hai Ning;Wang,Jialin;Qu,Yuanying;Yue,Yong


Abstract:Large interactive displays can provide suitable workspaces for learners to conduct collaborative learning tasks with visual information in co-located settings. In this research, we explored the use of these displays to support collaborative engagement and exploratory tasks with visual representations. Our investigation looked at the effect of four factors (number of virtual workspaces within the display, number of displays, position arrangement of the collaborators, and collaborative modes of interaction) on learners’ knowledge acquisition, engagement level, and task performance. To this end, a user study was conducted with 72 participants divided into 6 groups using an interactive tool developed to support the collaborative exploration of 3D visual structures. The results of this study showed that learners with one shared workspace and one single display can achieve better user performance and engagement levels. In addition, the back-to-back position with learners sharing their view and control of the workspaces was the most favorable. It also led to improved learning outcomes and engagement levels during the collaboration process.

5469.Leakage-Resilient Authenticated Key Exchange for Edge Artificial Intelligence

Author:Zhang, J;Zhang, FT;Huang, X;Liu, X


Abstract:Edge Artificial Intelligence (AI) is a timely complement of cloud-based AI. By introducing intelligence to the edge, it alleviates privacy concerns of streaming and storing data to the cloud, enables real-time operations where milliseconds matter, and brings AI services to remote areas with poor networking infrastructures. Security is a significant problem in Edge AI applications such as self-driving cars and intelligent healthcare. Since the edge devices are empowered to process data and take actions, attacking and compromising them can cause serious damage. However, the wide deployment of computationally limited devices in edge environments and the increasing happening of side-channel (or leakage) attacks pose critical challenges to security. This article thereby aims to enhance the security for Edge AI by designing and developing lightweight and leakage-resilient authenticated key exchange (LRAKE) protocols. Compared with available LRAKE protocols, the proposed protocols in this article can be effortless applied in some mainstreaming security and communication standards. Moreover, this article realizes prototypes and presents implementation details; and a use case of applying the proposed protocol in Bluetooth 5.0 is illustrated. The theoretical design and implementation details will provide a guidance of applying the LRAKE protocols in Edge AI applications.

5470.Soil properties as key predictors of global grassland production: Have we overlooked micronutrients?

Author:Radujkovic, D;Verbruggen, E;Seabloom, EW;Bahn, M;Biederman, LA;Borer, ET;Boughton, EH;Catford, JA;Campioli, M;Donohue, I;Ebeling, A;Eskelinen, A;Fay, PA;Hansart, A;Knops, JMH;MacDougall, AS;Ohlert, T;Venterink, HO;Raynaud, X;Risch, AC;Roscher, C;Schutz, M;Silveira, ML;Stevens, CJ;Van Sundert, K;Virtanen, R;Wardle, GM;Wragg, PD;Vicca, S

Source:ECOLOGY LETTERS,2021,Vol.

Abstract:Fertilisation experiments have demonstrated that nutrient availability is a key determinant of biomass production and carbon sequestration in grasslands. However, the influence of nutrients in explaining spatial variation in grassland biomass production has rarely been assessed. Using a global dataset comprising 72 sites on six continents, we investigated which of 16 soil factors that shape nutrient availability associate most strongly with variation in grassland aboveground biomass. Climate and N deposition were also considered. Based on theory-driven structural equation modelling, we found that soil micronutrients (particularly Zn and Fe) were important predictors of biomass and, together with soil physicochemical properties and C:N, they explained more unique variation (32%%) than climate and N deposition (24%%). However, the association between micronutrients and biomass was absent in grasslands limited by NP. These results highlight soil properties as key predictors of global grassland biomass production and point to serial co-limitation by NP and micronutrients.

5471.Nutrient identity modifies the destabilising effects of eutrophication in grasslands

Author:Carroll, O;Batzer, E;Bharath, S;Borer, ET;Campana, S;Esch, E;Hautier, Y;Ohlert, T;Seabloom, EW;Adler, PB;Bakker, JD;Biederman, L;Bugalho, MN;Caldeira, M;Chen, QQ;Davies, KF;Fay, PA;Knops, JMH;Komatsu, K;Martina, JP;McCann, KS;Moore, JL;Morgan, JW;Muraina, TO;Osborne, B;Risch, AC;Stevens, C;Wilfahrt, PA;Yahdjian, L;MacDougall, AS

Source:ECOLOGY LETTERS,2021,Vol.

Abstract:Nutrient enrichment can simultaneously increase and destabilise plant biomass production, with co-limitation by multiple nutrients potentially intensifying these effects. Here, we test how factorial additions of nitrogen (N), phosphorus (P) and potassium with essential nutrients (K+) affect the stability (mean/standard deviation) of aboveground biomass in 34 grasslands over 7 years. Destabilisation with fertilisation was prevalent but was driven by single nutrients, not synergistic nutrient interactions. On average, N-based treatments increased mean biomass production by 21-51%% but increased its standard deviation by 40-68%% and so consistently reduced stability. Adding P increased interannual variability and reduced stability without altering mean biomass, while K+ had no general effects. Declines in stability were largest in the most nutrient-limited grasslands, or where nutrients reduced species richness or intensified species synchrony. We show that nutrients can differentially impact the stability of biomass production, with N and P in particular disproportionately increasing its interannual variability.

5472.Microbial biofilms on a giant monolithic statue of Buddha: The symbiosis of microorganisms and mosses and implications for bioweathering

Author:Bai, FY;Chen, XP;Huang, JZ;Lu, YS;Dong, HY;Wu, YH;Song, SL;Yu, J;Bai, S;Chen, Z;Yang, TY;Peng, XY


Abstract:Monolithic statues of Buddha are important cultural heritage objects. The inevitable coverage by moss with associated microorganisms is believed to drive weathering, but the functions of moss in bioweathering are still unclear. In this study, mosses and their associated microorganisms of the Leshan Giant Buddha in China from three distinct periods (e.g., growing, senescent, and residual) were examined using High-throughput sequencing and quantitative PCR techniques. The results showed that the period of active moss growth rather than species had a regulatory role on the microenvironment, which further affected the microbial communities and metabolism. The higher frequency of nucleotide sequences related to enzymes of nutrient cycling and weathering in the growing period indicated active interaction between microorganisms and substrate. Moss growth increased energy allocation to substratum surface through photosynthesis. Higher abundance of the ammonia monooxygenase gene (amoA) of the ammonia-oxidizing archaea was detected and responsible for nitrogen transformation. In particular, moss growth promoted iron-associated processes and likely electron transport processes. Iron-reducing bacteria were the main players responsible for transforming iron oxides on the statue. It is concluded that moss growth plays an important role in driving microbial weathering. This study highlights the urgency of moss symbiosis control for protecting monolithic statues in the field.

5473.Design and optimization of modular multilevel DC transformer


Source:Proceedings of the 16th IEEE Conference on Industrial Electronics and Applications, ICIEA 2021,2021,Vol.

Abstract:Modern science and technology are developing rapidly, the power industry is also developing at a high speed, the traditional transformer is more and more difficult to content the requirement of the power system. Power electronic transformer (PET) is a kind of composite installation composed of power electronic converter and high frequency transformer. It can realize voltage conversion, electrical isolation and energy transmission functions of traditional transformer, and can also control voltage and current in power system and intelligent management. It is the best choice to realize voltage transformation function in modern power system. Compared with the traditional power electronic transformer, a power electronic transformer with lower device failure loss and better output waveform is proposed, the modular multilevel converter (MMC), which has a highly modular architecture. This essay revolves about the new type of MMC based power electronic transformer in the medium voltage distribution network, which adopts a three stage topology made up of the high voltage input stage, the intermediate isolation stage and the low voltage output stage. The input stage uses the MMC structure, the isolation stage is composed of several input series output parallel (ISOP) double active bridge DC/DC converters, and the output stage uses the traditional three-phase four leg inverter topology. This paper introduces the development process and the development direction of the power electronic transformer in recent years, analyzes and discusses the principle of three parts of power electronic transformer, and expounds the expected experimental results at the end of the paper.

5474.Computationally Efficient Model Predictive Control with Fixed Switching Frequency of Five-Level ANPC Converters


Source:IEEE Transactions on Industrial Electronics,2021,Vol.

Abstract:This paper proposes a fixed switching frequency (FSF) based improved model predictive control (MPC) for a five-level active neutral-point clamped converter (5L-ANPC). Compared to the conventional MPC for 5L-ANPC, the proposed MPC significantly reduces the computational burden while ensuring the balance of DC-link and flying capacitor voltages. The proposed MPC optimally selects the control voltage vectors to reduce the common mode voltage (CMV), leading to a small CMV of the converter. Using three-voltage-vectors actions per control cycle in MPC, FSF is achieved. The steady-state and dynamic performance of the proposed MPC has been evaluated by experiments. The results verify the feasibility and effectiveness of the proposed MPC method.

5475.A Comparative Review of High-Frequency Transient DC Bias Current Mitigation Strategies in Dual-Active-Bridge DC-DC Converters Under Phase-Shift Modulations


Source:IEEE Transactions on Industry Applications,2021,Vol.

Abstract:Dual-active-bridge (DAB) converters have been widely recognized as one promising topology for high-frequencylink power conversion applications. However, one critical issue concerning DAB converters is the transient dc-bias current due to the voltage-second imbalance, which may occur frequently in typical dynamic operations of DAB converters such as the start-up, sudden load or output voltage change, and power flow direction change. Due to the high-frequency operation, the dc-bias current of DAB converters will impose more harm to magnetic components because of the limited range of operating flux density and possible magnetic saturation compared with the counterpart low-frequency dc-bias current. Over the past several years, extensive researches have been conducted to address the high-frequency transient dc-bias current of DAB converters under different phase-shift modulation strategies such as single phase shift (SPS), extended phase shift (EPS), and triple phase shift (TPS). In this paper, a comparative review of typical dc-bias current mitigation strategies under typical phase-shift strategies for DAB converters is presented. An experimental evaluation of selected strategies under various scenarios is conducted in terms of the settling time, inductor current stress, efficiency, switching number, and implementation complexity. This paper ends up with an overview of high-frequency dc-bias mitigation strategies and a discussion for the further optimization.

5476.2021 IEEE 3rd global conference on life sciences and technologies (LifeTech 2021) design of an auxiliary device for home-based stroke rehabilitation

Author:Zhang,Shuhao;Huang,Mengjie;Wang,Liu;Liao,Kai Lun;Yang,Rui

Source:LifeTech 2021 - 2021 IEEE 3rd Global Conference on Life Sciences and Technologies,2021,Vol.

Abstract:Home-based rehabilitation is playing a significant role in patients with stroke after leaving hospital as an accessible rehabilitation approach. This paper proposes a home-based rehabilitation auxiliary device used with wheelchair for patients after stroke, especially those with lateral asymmetry in upper limbs. This device relies on an electrical system to track the movement of the patient's upper limb on the dominant side to drive the weaker side’s movement. Design concept, interaction design process, and results are demonstrated in detail in this paper to illustrate the novel auxiliary device design for rehabilitation. This design provides a new way for upper limb training for patients with rehabilitation at home. Moreover, further exploration of integrating a virtual reality game with this device is also presented for increasing the user’s motivation in training.

5477.Fast pixel-matching for video object segmentation

Author:Yu, SY;Xiao, JM;Zhang, BF;Lim, EG;Zhao, Y


Abstract:Video object segmentation, aiming to segment the foreground objects given the annotation of the first frame, has been attracting increasing attentions. Many state-of-the-art approaches have achieved great performance by relying on online model updating or mask-propagation techniques. However, most online models require high computational cost due to model fine-tuning during inference. Most mask-propagation based models are faster but with relatively low performance due to failure to adapt to object appearance variation. In this paper, we are aiming to design a new model to make a good balance between speed and performance. We propose a model, called NPMCA-net, which directly localizes foreground objects based on mask-propagation and non-local technique by matching pixels in reference and target frames. Since we bring in information of both first and previous frames, our network is robust to large object appearance variation, and can better adapt to occlusions. Extensive experiments show that our approach can achieve a new state-of-the-art performance with a fast speed at the same time (86.5%% IoU on DAVIS-2016 and 72.2%% IoU on DAVIS-2017, with speed of 0.11s per frame) under the same level comparison. Source code is available at

5478.An Intelligent Customer Service System for Securities Industry based on Compound Corpus and Text Vector


Source:Proceedings - 2021 3rd International Conference on Advances in Computer Technology, Information Science and Communication, CTISC 2021,2021,Vol.

Abstract:Customer service is one of essential tasks for securities companies. The traditional manual service mode has disadvantages such as high labour intensity and poor customer service experience. This paper proposes an intelligent customer service system based on Fasttext and word vectors. By constructing the securities knowledge database, and using Fasttext to train the word vector model from the Chinese compound corpus, the performance of 'sentence vector + cosine distance' and 'word vector similarity matrix + CNN feature extraction' methods in calculating semantic similarity are analyzed based on single corpus and compound corpus, respectively. The results show that 'sentence vector + cosine distance' has higher performance on accuracy rate.

5479.IText: Hands-free Text Entry on an Imaginary Keyboard for Augmented Reality Systems

Author:Lu,Xueshi;Yu,DIfeng;Liang,Hai Ning;Goncalves,Jorge

Source:UIST 2021 - Proceedings of the 34th Annual ACM Symposium on User Interface Software and Technology,2021,Vol.

Abstract:Text entry is an important and frequent task in interactive devices including augmented reality head-mounted displays (AR HMDs). In current AR HMDs, there are still two main open challenges to overcome for efficient and usable text entry: arm fatigue due to mid-air input and visual occlusion because of their small see-through displays. To address these challenges, we present iText, a technique for AR HMDs that is hands-free and is based on an imaginary (invisible) keyboard. We first show that it is feasible and practical to use an imaginary keyboard on AR HMDs. Then, we evaluated its performance and usability with three hands-free selection mechanisms: eye blinks (E-Type), dwell (D-Type), and swipe gestures (G-Type). Our results show that users could achieve an average text entry speed of 11.95, 9.03 and 9.84 words per minutes (WPM) with E-Type, D-Type, and G-Type, respectively. Given that iText with E-Type outperformed the other two selection mechanisms in text entry rate and subjective feedback, we ran a third, 5-day study. Our results show that iText with E-Type can achieve an average text entry rate of 13.76 WPM with a mean word error rate of 1.5%%. In short, iText can enable efficient eyes-free text entry and can be useful for various application scenarios in AR HMDs.

5480.Myopic bike and say Hi: Games for empathizing with the myopic

Author:Li,Xiang;Tang,Xiaohang;Tong,Xin;Patibanda,Rakesh;Mueller,Floyd;Liang,Hai Ning

Source:CHI PLAY 2021 - Extended Abstracts of the 2021 Annual Symposium on Computer-Human Interaction in Play,2021,Vol.

Abstract:Myopia is an eye condition that makes it difficult for people to focus on faraway objects. It has become one of the most serious eye conditions worldwide and negatively impacts the quality of life of those who suffer from it. Although myopia is prevalent, many non-myopic people have misconceptions about it and encounter challenges empathizing those who suffer from it. In this research, we developed two virtual reality (VR) games, (1) "Myopic Bike"and (2) "Say Hi", to provide a means for the non-myopic population to experience the difficulties of myopic people. Our two games simulate two inconvenient daily life scenarios (riding a bicycle and greeting friends on the street) that myopic people encounter when not wearing glasses. The goal is to facilitate empathy in people with non-myopia for those who suffer from myopia. We evaluated four participants' game experiences through questionnaires and semi-structured interviews. Overall, our two VR games can create an engaging and non-judgmental experience for the non-myopic people that has potential to facilitate empathizing with those who suffer from myopia.
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