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1.Advances in freshwater risk assessment: improved accuracy of dissolved organic matter-metal speciation prediction and rapid biological validation

Author:Zhang, XK;Li, BL;Deng, JM;Qin, BQ;Wells, M;Tefsen, B


Abstract:Speciation modeling of bioavailability has increasingly been used for environmental risk assessment (ERA). Heavy metal pollution is the most prevalent environmental pollution issue globally, and metal bioavailability is strongly affected by its chemical speciation. Dissolved organic matter (DOM) in freshwater will bind heavy metals thereby reducing bioavailability. While speciation modeling has been shown to be quite effective and is validated for use in ERA, there is an increasing body of literature reporting problems with the accuracy of metalDOM binding in speciation models. In this study, we address this issue for a regional-scale field area (Lake Tai, with 2,400 km(2) surface area and a watershed of 36,000 km(2)) where speciation models in common use are not highly accurate, and we tested alternative approaches to predict metal-DOM speciation/bioavailability for lead (Pb) in this first trial work. We tested five site-specific approaches to quantify Pb-DOM binding that involve varying assumptions about conditional stability constants, binding capacities, and different components in DOM, and we compare these to what we call a one-size-fits-all approach that is commonly in use. We compare model results to results for bioavailable Pb measured using a whole-cell bioreporter, which has been validated against speciation models and is extremely rapid compared to many biological methods. The results show that all of the site-specific approaches we use provide more accurate estimates of bioavailability than the default model tested, however, the variation of the conditional stability constant on a site-specific basis is the most important consideration. By quantitative metrics, up to an order of magnitude improvement in model accuracy results from modeling active DOM as a single organic ligand type with site-specific variations in Pb-DOM conditional stability constants. Because the biological method is rapid and parameters for site-specific tailoring of the model may be obtained via high-throughput analysis, the approach that we report here in this first regional-scale freshwater demonstration shows excellent potential for practical use in streamlined ERA.

2.Biophysical characterizations of human mitochondrial transcription factor A and its binding to tumor suppressor p53

Author:Wong, TS;Rajagopalan, S;Freund, SM;Rutherford, TJ;Andreeva, A;Townsley, FM;Petrovich, M;Fersht, AR


Abstract:Human mitochondrial transcription factor A (TFAM) is a multi-functional protein, involved in different aspects of maintaining mitochondrial genome integrity. In this report, we characterized TFAM and its interaction with tumor suppressor p53 using various biophysical methods. DNA-free TFAM is a thermally unstable protein that is in equilibrium between monomers and dimers. Self-association of TFAM is modulated by its basic C-terminal tail. The DNA-binding ability of TFAM is mainly contributed by its first HMG-box, while the second HMG-box has low-DNA-binding capability. We also obtained backbone resonance assignments from the NMR spectra of both HMG-boxes of TFAM. TFAM binds primarily to the N-terminal transactivation domain of p53, with a K-d of 1.95 +/- 0.19 mu M. The C-terminal regulatory domain of p53 provides a secondary binding site for TFAM. The TFAM-p53-binding interface involves both TAD1 and TAD2 sub-domains of p53. Helices alpha 1 and alpha 2 of the HMG-box constitute the main p53-binding region. Since both TFAM and p53 binds preferentially to distorted DNA, the TFAM-p53 interaction is implicated in DNA damage and repair. In addition, the DNA-binding mechanism of TFAM and biological relevance of the TFAM-p53 interaction are discussed.

3.Low-Complexity Noncoherent Signal Detection for Nanoscale Molecular Communications

Author:Li, B;Sun, MW;Wang, SY;Guo, WS;Zhao, CL


Abstract:Nanoscale molecular communication is a viable way of exchanging information between nanomachines. In this investigation, a low-complexity and noncoherent signal detection technique is proposed to mitigate the inter-symbol-interference (ISI) and additive noise. In contrast to existing coherent detection methods of high complexity, the proposed noncoherent signal detector is more practical when the channel conditions are hard to acquire accurately or hidden from the receiver. The proposed scheme employs the molecular concentration difference to detect the ISI corrupted signals and we demonstrate that it can suppress the ISI effectively. The difference in molecular concentration is a stable characteristic, irrespective of the diffusion channel conditions. In terms of complexity, by excluding matrix operations or likelihood calculations, the new detection scheme is particularly suitable for nanoscale molecular communication systems with a small energy budget or limited computation resource.

4.Outbreak analysis with a logistic growth model shows COVID-19 suppression dynamics in China

Author:Zou, Y;Pan, S;Zhao, P;Han, L;Wang, XX;Hemerik, L;Knops, J;van der Werf, W

Source:PLOS ONE,2020,Vol.15

Abstract:China reported a major outbreak of a novel coronavirus, SARS-CoV2, from mid-January till mid-March 2020. We review the epidemic virus growth and decline curves in China using a phenomenological logistic growth model to summarize the outbreak dynamics using three parameters that characterize the epidemic's timing, rate and peak. During the initial phase, the number of virus cases doubled every 2.7 days (range 2.2-4.4 across provinces). The rate of increase in the number of reported cases peaked approximately 10 days after suppression measures were started on 23-25 January 2020. The peak in the number of reported sick cases occurred on average 18 days after the start of suppression measures. From the time of starting measures till the peak, the number of cases increased by a factor 39 in the province Hubei, and by a factor 9.5 for all of China (range: 6.2-20.4 in the other provinces). Complete suppression took up to 2 months (range: 23-57d.), during which period severe restrictions, social distancing measures, testing and isolation of cases were in place. The suppression of the disease in China has been successful, demonstrating that suppression is a viable strategy to contain SARS-CoV2.

5.The behavioural causes of bullwhip effect in supply chains: A systematic literature review

Author:Yang, Y;Lin, J;Liu, G;Zhou, L


Abstract:The bullwhip effect, also known as demand information amplification, is one of the principal obstacles in supply chains. In recent decades, extensive studies have explored its operational causes and have proposed corresponding solutions in the context of production inventory and supply chain systems. However, the underlying assumption of these studies is that human decision-making is always rational. Yet, this is not always the case, and an increasing number of recent studies have argued that behavioural and psychological factors play a key role in generating the bullwhip effect in real-world supply chains. Given the prevalence of such research, the main objective of this study is to provide a systematic literature review on the bullwhip effect from the behavioural operations perspective. Using databases, including Scopus, Wiley Online Library, Google Scholar and Science Direct, we selected, summarised and analysed 53 academic studies. We find that most studies build their models and simulations based on the 'beer distribution game' and analyse the results at the individual level. We also demonstrate the importance of studying human factors in the bullwhip effect through adapting Sterman's double-loop learning model. Based on this model, we categorise and analyse the behavioural factors that have been studied and identify the explored behavioural factors for future research. Based on our findings, we suggest that future studies could consider social and cultural influences on decision-making in studying the bullwhip effect. In addition, further aspects of human mental models that cause this effect can be explored.

6.A Handshake Protocol With Unbalanced Cost for Wireless Updating

Author:Cai, JR;Huang, X;Zhang, J;Zhao, JW;Lei, YX;Liu, DW;Ma, XF

Source:IEEE ACCESS,2018,Vol.6

Abstract:Wireless updating is an essential method to update system files or fix bugs in Internet of Things (IoT) devices. A significant and challenging problem in wireless updating is security. First, without security guarantees, attackers can utilize the updating procedure to install harmful programs into the victim devices. Second, it is challenging to provide security for wireless updating, since in many IoT scenarios, the devices to be updated are computationally limited devices and located far from the center that issues update files. Currently, there are two types of solution to protect the wireless updating. The first one is the transport layer security (TLS) protocol or secure sockets layer (SSL) protocol that are used by wireless updating schemes for mobile terminals with the following operation systems: Windows, Debian, Android, and iOS. Another solution is the elliptic curve Diffie-Hellman (ECDH)-based handshake in the software-defined function (SDF) wireless updating scheme for the IoT devices. However, both the two solutions require equal computation tasks on the update file issuing center and the device to be updated. Normally, the former is much powerful than the latter. Therefore, to further address the security problem in wireless updating, we propose a novel solution with unbalanced computation costs on the two parties. In particular, we design an improved ECDH-based handshake protocol for the SDF wireless updating scheme, namely, the unbalanced OpenFunction handshake protocol. The protocol transfers significant computation task from the limited IoT device to the powerful center. The security of the protocol is analyzed. A prototype is realized to test the performance of the protocol. The experiment results show that in the same experimental platform, our protocol is much lightweight than the TLS handshake protocol and SSL handshake protocol.

7.On the theoretical distribution of the wind farm power when there is a correlation between wind speed and wind turbine availability

Author:Kan, C;Devrim, Y;Eryilmaz, S


Abstract:It is important to elicit information about the potential power output of a wind turbine and a wind farm consisting of specified number of wind turbines before installation of the turbines. Such information can be used to estimate the potential power output of the wind farm which will be built in a specific region. The output power of a wind turbine is affected by two factors: wind speed and turbine availability. As shown in the literature, the correlation between wind speed and wind turbine availability has an impact on the output of a wind farm. Thus, the probability distribution of the power produced by the farm depending on the wind speed distribution and turbine availability can be effectively used for planning and risk management. In this paper, the theoretical distribution of the wind farm power is derived by considering the dependence between turbine availability and the wind speed. The theoretical results are illustrated for real wind turbine reliability and wind speed data.

8.The isolation of a DNA aptamer to develop a fluorescent aptasensor for the thiamethoxam pesticide

Author:Luo, Y;Jin, ZY;Wang, JN;Ding, P;Pei, RJ


Abstract:Aptamers, which are called chemical antibodies for their high affinity and specificity to targets, have great potential as analytical tools to detect pesticides. In this work, a DNA aptamer for thiamethoxam was isolated by an improved SELEX (systematic evolution of ligands by exponential enrichment) strategy, in which the ssDNA library was fixed on streptavidin-agarose beads through a short biotin labeled complementary strand. After 13 rounds of selection, the random ssDNA pool was successfully enriched. Three sequences were chosen as aptamer candidates through sequencing and analysis and were transformed into fluorescent probes to evaluate their interactions with thiamethoxam. A fluorescent turn-on aptasensor for thiamethoxam based on the best aptamer (FAM-Thi13) and a short quenching strand were further designed and showed a quantitative linear range from 10 to 1000 nM with a detection limit of 1.23 nM for thiamethoxam. Molecular docking and molecular dynamics were used to investigate the binding site of the main probe of the aptasensor (FAM-Thi13) and thiamethoxam. Satisfactory results were also obtained in quantifying thiamethoxam in environmental water samples by the developed fluorescent aptasensor.

9.SLP-76 Sterile alpha Motif (SAM) and Individual H5 alpha Helix Mediate Oligomer Formation for Microclusters and T-cell Activation

Author:Liu, HB;Thaker, YR;Stagg, L;Schneider, H;Ladbury, JE;Rudd, CE


Abstract:Despite the importance of the immune adaptor SLP-76 in T-cell immunity, it has been unclear whether SLP-76 directly self-associates to form higher order oligomers for T-cell activation. In this study, we show that SLP-76 self-associates in response to T-cell receptor ligation as mediated by the N-terminal sterile alpha motif (SAM) domain. SLP-76 co-precipitated alternately tagged SLP-76 in response to anti-CD3 ligation. Dynamic light scattering and fluorescent microscale thermophoresis of the isolated SAM domain (residues 1-78) revealed evidence of dimers and tetramers. Consistently, deletion of the SAM region eliminated SLP-76 co-precipitation of itself, concurrent with a loss of microcluster formation, nuclear factor of activated T-cells (NFAT) transcription, and interleukin-2 production in Jurkat or primary T-cells. Furthermore, the H5 alpha helix within the SAM domain contributed to self-association. Retention of H5 in the absence of H1-4 sufficed to support SLP-76 self-association with smaller microclusters that nevertheless enhancedanti-CD3-drivenAP1/NFAT transcription and IL-2 production. By contrast, deletion of the H5 alpha helix impaired self-association and anti-CD3 induced AP1/NFAT transcription. Our data identified for the first time a role for the SAM domain in mediating SLP-76 self-association for T-cell function.

10.Infrared motion detection and electromyographic gesture recognition for navigating 3D environments

Author:Chen, KY;Liang, HN;Yue, Y;Craig, P


Abstract:This research explores the suitability and effectiveness of two relatively new types of input device for navigating 3D virtual environments. These are infrared motion detection, like the Leap Motion tracker, and electromyographic gesture recognition, like the Myo Armband. Despite the introduction of a variety of new input devices intended to provide a more natural interaction experience, navigation within 3D virtual environments is still normally done on more traditional control devices such as game controllers or the keyboard-mouse combination. This study investigates the potential of new devices to support navigation in 3D environments through an experiment conducted with 27 participants using three different types of input devices to play a ball-balancing maze-like game. The input devices tested are a standard game controller, a Leap Motion tracker for infrared motion detection, and the Myo Armband for electromyographic gesture recognition. Results demonstrated the real potential of both types of device to support navigation interaction within 3D environments.

11.Effects of China's urban basic health insurance on preventive care service utilization and health behaviors: Evidence from the China Health and Nutrition Survey

Author:Dong, WY;Gao, JM;Zhou, ZL;Bai, RH;Wu, Y;Su, M;Shen, C;Lan, X;Wang, X

Source:PLOS ONE,2018,Vol.13

Abstract:Background Lifestyle choices are important determinants of individual health. Few studies have investigated changes in health behaviors and preventive activities brought about by the 2007 implementation of Urban Resident Basic Health Insurance (URBMI) in China. This study, therefore, aimed to explore whether URBMI has reduced individuals' incentives to adopt healthy behaviors and utilize preventive care services. Methods Data were drawn from two waves of the China Health and Nutrition Survey. Respondents were categorized according to their insurance situation before and after the URBMI reform in 2006 and 2011. Propensity score matching and difference-in-differences methods were used to measure levels of preventive care and behavior changes over time. Estimations were also made based on gender, self-reported health, and income. Results We found that URBMI implementation did not change residents' utilization of preventive care services or their smoking habits, drinking habits, or other risky behaviors overall. However, the likelihood of sedentariness did increase by five percentage points. Females tended to be more sedentary while males were less likely to drink soft drinks. Residents with poor self-reported health exercised less while those who reported good health were more likely to be sedentary. Low-and middle-income residents were likely to be sedentary while middle-income people tended to smoke after becoming insured. Conclusion Since URBMI implementation, some unhealthy behaviors like sedentariness have increased among those who were newly insured, and different subgroups have reacted differently. This suggests that the insurance design needs to be optimized and effective measures need to be adopted to help improve people's lifestyle choices.

12.Equivalent Extensions to Caristi-Kirk's Fixed Point Theorem, Ekeland's Variational Principle, and Takahashi's Minimization Theorem

Author:Wu, ZL


Abstract:With a recent result of Suzuki (2001) we extend Caristi-Kirk's fixed point theorem, Ekeland's variational principle, and Takahashi's minimization theorem in a complete metric space by replacing the distance with a tau-distance. In addition, these extensions are shown to be equivalent. When the tau-distance is l.s.c. in its second variable, they are applicable to establish more equivalent results about the generalized weak sharp minima and error bounds, which are in turn useful for extending some existing results such as the petal theorem.

13.Coupling of the Crank–Nicolson scheme and localized meshless technique for viscoelastic wave model in fluid flow

Author:Nikan, O. ; Avazzadeh, Z.

Source:Journal of Computational and Applied Mathematics,2021,Vol.398

Abstract:This paper proposes an efficient localized meshless technique for approximating the viscoelastic wave model. This model is a significant methodology to explain wave propagation in solids modeled with a wide collection of viscoelastic laws. In the first method, a difference scheme with the second-order accuracy is implemented to obtain a semi-discrete scheme. Then, a localized radial basis function partition of unity scheme is adopted to get a full-discrete scheme. This localization technique consists of decomposing the initial domain into several sub-domains and constructing a local radial basis function approximation over every sub-domain. A well-conditioned resulting linear system and a low computational burden are the main merits of this technique compared to global collocation methods. Further, the stability and convergence analysis of the temporal discretization scheme are deduced using discrete energy method. Numerical results are shown to validate the accuracy and effectiveness of the proposed method. © 2021

14.Improved catalytic oxidation of propylene glycol methyl ether over Sm-Mn and Sm-Co perovskite-based catalysts prepared by the recycling of spent ternary lithium-ion battery

Author:Sun, JT;Liu, LZ;Zhang, Y;Guo, MM;Zhou, B


Abstract:The spent ternary lithium-ion batteries were utilized as the precursors to prepare Sm-Mn and Sm-Co perovskite oxides (SmMnO3-spent ternary lithium-ion battery [STLIB] and SmCoO3-STLIB) for the first time. Their catalytic activities were evaluated by catalytic oxidation of propylene glycol methyl ether. Compared with that of the catalysts synthesized by analytical reagents, the catalytic activities of SmMnO3-STLIB and SmCoO3-STLIB had been significantly enhanced. The analysis of X-ray photoelectron spectroscopy (XPS) showed that the molar ratios of Mn4+/Mn3+ and O-ads/O-latt of SmMnO3-STLIB were higher than that of pure SmMnO3 and the Co3+/Co2+ ratios of SmCoO3-STLIB was much larger than that of pure SmCoO3. The hydrogen temperature-programmed reduction (H-2-TPR) and N-2 adsorption-desorption tests determined that the reducibilities and specific surface areas of SmMnO3-STLIB and SmCoO3-STLIB were also superior to pure catalysts. Ultimately, the by-products of the catalytic oxidation of propylene glycol methyl ether over SmMnO3-STLIB were also detected by gas chromatography-mass spectrometry (GC-MS). This work will provide a demonstration for the resource utilization of spent lithium ions batteries and the analysis of the increased activity obtained by using spent lithium ions batteries as the precursors to prepare catalysts.

15.Designing an Optimized Water Quality Monitoring Network with Reserved Monitoring Locations

Author:Zhu, XH;Yue, Y;Wong, PWH;Zhang, YX;Ding, H


Abstract:The optimized design of water quality monitoring networks can not only minimize the pollution detection time and maximize the detection probability for river systems but also reduce redundant monitoring locations. In addition, it can save investments and costs for building and operating monitoring systems as well as satisfy management requirements. This paper aims to use the beneficial features of multi-objective discrete particle swarm optimization (MODPSO) to optimize the design of water quality monitoring networks. Four optimization objectives: minimum pollution detection time, maximum pollution detection probability, maximum centrality of monitoring locations and reservation of particular monitoring locations, are proposed. To guide the convergence process and keep reserved monitoring locations in the Pareto frontier, we use a binary matrix to denote reserved monitoring locations and develop a new particle initialization procedure as well as discrete functions for updating particle's velocity and position. The storm water management model (SWMM) is used to model a hypothetical river network which was studied in the literature for comparative analysis of our work. We define three pollution detection thresholds and simulate pollution events respectively to obtain all the pollution detection time for all the potential monitoring locations when a pollution event occurs randomly at any potential monitoring locations. Compared to the results of an enumeration search method, we confirm that our algorithm could obtain the Pareto frontier of optimized monitoring network design, and the reserved monitoring locations are included to satisfy the management requirements. This paper makes fundamental advancements of MODPSO and enables it to optimize the design of water quality monitoring networks with reserved monitoring locations.

16.Driving posture recognition by convolutional neural networks

Author:Yan, C;Coenen, F;Zhang, BL

Source:IET COMPUTER VISION,2016,Vol.10

Abstract:Driver fatigue and inattention have long been recognised as the main contributing factors in traffic accidents. This study presents a novel system which applies convolutional neural network (CNN) to automatically learn and predict pre-defined driving postures. The main idea is to monitor driver hand position with discriminative information extracted to predict safe/unsafe driving posture. In comparison to previous approaches, CNNs can automatically learn discriminative features directly from raw images. In the authors' works, a CNNmodel was first pre-trained by an unsupervised feature learning method called sparse filtering, and subsequently fine-tuned with classification. The approach was verified using the Southeast University driving posture dataset, which comprised of video clips covering four driving postures, including normal driving, responding to a cell phone call, eating, and smoking. Compared with other popular approaches with different image descriptors and classification methods, the authors' scheme achieves the best performance with an overall accuracy of 99.78%%. To evaluate the effectiveness and generalisation performance in more realistic conditions, the method was further tested using other two specially designed datasets which takes into account of the poor illuminations and different road conditions, achieving an overall accuracy of 99.3 and 95.77%%, respectively.

17.Mild-to-moderate iodine deficiency in a sample of pregnant women and salt iodine concentration from Zhejiang province, China

Author:Yu, ZL;Zheng, CJ;Zheng, WF;Wan, ZX;Bu, YJ;Zhang, GF;Ding, SB;Wang, EH;Zhai, DS;Ma, ZF


Abstract:Since 2011, Zhejiang province has eliminated iodine deficiency disorders (IDD) in its populations. Following this achievement, a new revised iodine concentration in iodised salt was implemented in Zhejiang in 2012. However, the re-emergence of iodine deficiency has been reported in pregnant women. Therefore, the aim of this study was to assess household salt iodine concentration and iodine status of pregnant women in Zhejiang province, China. We conducted a cross-sectional study between April 2018 and August 2018 in Quzhou, Zhejiang province. Pregnant women aged >= 18 years who did not have a history of thyroid disease were recruited into the study. They were asked to complete socio-demographic questionnaires including a food frequency questionnaire (FFQ). In addition, a spot urine sample and a household table salt sample were also provided by each participant. A total of 625 pregnant women agreed to participate. The overall median urinary iodine concentration (UIC) was 130 mu g/L, indicating mild-to-moderate iodine deficiency in pregnant women. The coverage of iodised salt was 85.2%%, and of these, the rate of adequately iodised salt was 98.1%%. In conclusion, our results confirmed the re-emergence of iodine deficiency in pregnant women as reported by other studies conducted in Zhejiang province. Therefore, urgent public health actions are needed to improve iodine status of pregnant women in order to prevent the adverse consequences of IDD on the neurodevelopment of foetus.

18.Particle swarm Optimized Density-based Clustering and Classification: Supervised and unsupervised learning approaches

Author:Guan, C;Yuen, KKF;Coenen, F


Abstract:Two pattern recognition technologies in the field of machine learning, clustering and classification, have been applied in many domains. Density-based clustering is an essential clustering algorithm. The best known density-based clustering method is Density-Based Spatial Clustering of Applications with Noise (DBSCAN), which can find arbitrary shaped clusters in datasets. DBSCAN has three drawbacks: firstly, the parameters for DBSCAN are hard to set; secondly, the number of clusters cannot be controlled by the users; and thirdly, DBSCAN cannot directly be used as a classifier. In this paper a novel Particle swarm Optimized Density-based Clustering and Classification (PODCC) is proposed, designed to offset the drawbacks of DBSCAN. Particle Swarm Optimization (PSO), a widely used Evolutionary and Swarm Algorithm (ESA), has been applied in optimization problems in different research domains including data analytics. In PODCC, a variant of PSO, SPSO-2011, is used to search the parameter space so as to identify the best parameters for density-based clustering and classification. PODCC can function in terms of both Supervised and Unsupervised Learnings by applying the appropriate fitness functions proposed in this paper. With the proposed fitness function, users can set the number of clusters as input for PODCC. The proposed method was evaluated by testing ten synthetic datasets and ten benchmarking datasets selected from various open sources. The experimental results indicate that the proposed PODCC can perform better than some established methods, especially with respect to imbalanced datasets.

19.Summer drought decreases Leymus chinensis productivity through constraining the bud, tiller and shoot production

Author:Wang, JF;Shi, YJ;Ao, YN;Yu, DF;Wang, J;Gao, S;Knops, JMH;Mu, CS;Li, ZJ


Abstract:Extreme drought events can directly decrease productivity in perennial grasslands. However, for rhizomatous perennial grasses it remains unknown how drought events influence the belowground bud bank which determines future productivity. Ninety-day-long drought events imposed on Leymus chinensis, a rhizomatous perennial grass, caused a 41%% decrease in the aboveground biomass and a 28%% decrease in belowground biomass. Aboveground biomass decreased due to decrease in both the parent and the daughter shoot biomass. The decreases in daughter shoot biomass were due to reductions in both the shoot number and each individual shoot weight. Most importantly, drought decreased the bud bank density by 56%%. In addition, drought induced a bud allocation change that decreased by 41%% the proportion of buds that developed into shoots and a 41%% increase in the buds that developed into rhizomes. Above results were supported by our field experiment with watering treatments. Thus, a 90-day-long summer drought event decreases not only current productivity but also future productivity, because the drought reduces the absolute bud number. However, plasticity in plant development does partly compensate for this reduction in bud number by increasing bud development into rhizomes, which increases the relative allocation of buds into future shoots, at the cost of a decrease in current shoots.

20.Au-Free AlGaN/GaN MIS-HEMTs With Embedded Current Sensing Structure for Power Switching Applications

Author:Sun, RZ;Liang, YC;Yeo, YC;Zhao, CZ


Abstract:AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) have become a promising candidate for use in efficient power conversion applications. In order to realize converter circuit control function and overcurrent protection of device itself, we have designed, fabricated, and experimentally measured the Au-free AlGaN/GaN MIS-HEMTs with embedded current sensing structure. A floating ohmic current sensing electrode is inserted between source and gate electrode of which the sensing voltage signal can represent the drain current. We have achieved stable current sensing ratios at various operating conditions including quasi-static, transient state, and under high temperature. The proposed structure is highly useful in monolithic power integrated circuit on CMOS-compatible AlGaN/GaN technologies.
Total 1,982 results found
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