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Probabilistic Global Maximum Power Point Tracking Algorithm for Continuously Varying Partial Shading Conditions on Autonomous PV Systems

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energy and Power engineering 2024年第1期16卷 21-42页

作者： kha Bao khanh Cao Vincent Boitier LAAS-CNRS University of Toulouse Toulouse France

A photovoltaic (PV) string with multiple modules with bypass diodes frequently deployed on a variety of autonomous PV systems may present multiple power peaks under uneven shading. For optimal solar harvesting, there is a need for a control schema to force the PV string to operate at global maximum power point (GMPP). While a lot of tracking methods have been proposed in the literature, they are usually complex and do not fully take advantage of the available characteristics of the PV array. This work highlights how the voltage at operating point and the forward voltage of the bypass diode are considered to design a global maximum power point tracking (GMPPT) algorithm with a very limited global search phase called Fast GMPPT. This algorithm successfully tracks GMPP between 94% and 98% of the time under a theoretical evaluation. It is then compared against Perturb and Observe, Deterministic Particle Swarm Optimization, and Grey Wolf Optimization under a sequence of irradiance steps as well as a power-over-voltage characteristics profile that mimics the electrical characteristics of a PV string under varying partial shading conditions. Overall, the simulation with the sequence of irradiance steps shows that while Fast GMPPT does not have the best convergence time, it has an excellent convergence rate as well as causes the least amount of power loss during the global search phase. experimental test under varying partial shading conditions shows that while the GMPPT proposal is simple and lightweight, it is very performant under a wide range of dynamically varying partial shading conditions and boasts the best energy efficiency (94.74%) out of the 4 tested algorithms.

关键词： Photovoltaic PV Global Maximum Power Point Tracking GMPPT Fast Varying Partial Shading Conditions Autonomous PV Systems GMPPT Review

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Developmental dependence for functional eye regrowth in Xenopus laevis

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Neural Regeneration Research 2018年第10期13卷 1735-1737页

作者： Cindy X.kha Kelly Ai-Sun Tseng School of Life Sciences University of Nevada

Introduction：A key challenge in designing tissue repair strategies is knowing whether and how developmental mechanisms are used for successful repair of mature/adult *** it is known that developmental components are used in repair,it remains mostly unclear which ones are required and whether they act similarly as during *** issue is further complicated by the fact that it is difficult.

关键词： Developmental dependence for functional eye regrowth in Xenopus laevis Figure RI

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A Comparative Study on environmental Degradation of Sundarbans due to Human Induced Causes（2008-2018）

A Comparative Study on Environmental Degradation of Sundarba...

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作者： Sudipto Sajol kha 西南交通大学

学位级别：硕士

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A Deep Learning Model of Traffic Signs in Panoramic Images Detection

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Intelligent Automation & Soft Computing 2023年第7期37卷 401-418页

作者： kha Tu Huynh Thi Phuong Linh Le Muhammad Arif Thien khai Tran International University Ho Chi Minh CityVietnam-Vietnam National UniversityHo Chi Minh City700000Vietnam Department of Computer Science The Superior UniversityLahorePakistan Ho Chi Minh City University of Foreign Languages and Information Technology Ho Chi Minh City700000Vietnam

To pursue the ideal of a safe high-tech society in a time when traffic accidents are frequent,the traffic signs detection system has become one of the necessary topics in recent years and in the *** ultimate goal of this research is to identify and classify the types of traffic signs in a panoramic *** accomplish this goal,the paper proposes a new model for traffic sign detection based on the Convolutional Neural Network for com-prehensive traffic sign classification and Mask Region-based Convolutional Neural Networks(R-CNN)implementation for identifying and extracting signs in panoramic *** augmentation and normalization of the images are also applied to assist in classifying better even if old traffic signs are degraded,and considerably minimize the rates of discovering the extra *** proposed model is tested on both the testing dataset and the actual images and gets 94.5%of the correct signs recognition rate,the classification rate of those signs discovered was 99.41%and the rate of false signs was only around 0.11.

关键词： Deep learning convolutional neural network Mask R-CNN traffic signs detection

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Buckling Analysis of FG Porous Truncated Conical Shells Resting on elastic Foundations in the Framework of the Shear Deformation Theory

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Advances in Applied Mathematics and Mechanics 2022年第1期14卷 218-247页

作者： Le kha Hoa Bui Gia Phi Do Quang Chan Dang Van Hieu Military Academy of logistics HanoiVietnam Department of Technical Fundamental University of Transport Technology54 Trieu Khuc9 Thanh XuanHanoiVietnam Department of Mechanical engineering and Mechatronics PHENIKAA UniversityHanoi 12116Vietnam PHeNIKAA Research and Technology Institute(PRATI) A&A Green Phoenix Group JSCNo.167 Hoang NganTrung HoaCau GiayHanoi 11313Vietnam Thainguyen University of Technology ThainguyenVietnam

In this article,an analytical method is proposed to analyze of the linear buckling behavior of the FG porous truncated conical shells subjected to a uniform axial compressive load and resting on the Pasternak elastic *** material properties including Young’s modulus,shear modulus and density are assumed to vary in the thickness *** types of FG porous distributions including symmetric porosity distribution,non-symmetric porosity and uniform porosity distribution are *** governing equations of the FG porous truncated conical shells are obtained by using the first-order shear deformation theory(FSDT).With the help of the Galerkin method,the expressions for critical buckling loads are obtained in closed *** reliability of the obtained results is verified by comparing the present solutions with the published ***,the numerical results show the effects of shell characteristics,porosity distribution,porosity coefficient,and elastic foundation on the critical buckling load.

关键词： Buckling truncated conical shells first order shear deformation theory porous materials elastic foundations

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A Deep Trash Classification Model on Raspberry Pi 4

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Intelligent Automation & Soft Computing 2023年第2期35卷 2479-2491页

作者： Thien khai Tran kha Tu Huynh Dac-Nhuong Le Muhammad Arif Hoa Minh Dinh Ho Chi Minh City University of Foreign Languages and Information Technology Ho Chi Minh City700000Vietnam International University Ho Chi Minh CityVietnam-Vietnam National UniversityHo Chi Minh City70000Vietnam Faculty of Information Technology Haiphong UniversityHaiphong180000Vietnam Department of Computer Science and Information Technology University of LahoreLahorePakistan

environmental pollution has had substantial impacts on human life,and trash is one of the main sources of such pollution in most *** classi-ﬁcation from a collection of trash images can limit the overloading of garbage dis-posal systems and efﬁciently promote recycling activities;thus,development of such a classiﬁcation system is topical and *** paper proposed an effective trash classiﬁcation system that relies on a classiﬁcation module embedded in a hard-ware setup to classify trash in real *** image dataset isﬁrst augmented to enhance the images before classifying them as either inorganic or organic *** deep learning–based ResNet-50 model,an improved version of the ResNet model,is used to classify trash from the dataset of trash *** experimental results,which are tested both on the dataset and in real time,show that ResNet-50 had an average accuracy of 96%,higher than that of related ***,integrating the classiﬁcation module into a Raspberry Pi computer,which con-trolled the trash bin slide so that garbage fell into the appropriate bin for inorganic or organic waste,created a complete trash classiﬁcation *** proves the efﬁciency and high applicability of the proposed system.

关键词： Trash classiﬁcation ResNet raspberry pi internet of things(IoT) deep learning

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Results of Testing Maize Hybrids on Lands Shifting from Rice-Growing Areas of Less efficiency in the Mekong Delta

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Journal of Agricultural Science and Technology(B) 2015年第4期5卷 241-246页

作者： Le Quy kha Institute of Agricultural Sciences for Southern Vietnam 121 Nguyen Binh Khiem Street District 1 Ho Chi Minh City Vietnam

Forecasters predict that by 2020 there will be 4.5 or 5 million tons per annum maize supply deficiency in Vietnam. As a result of this projection, the government responded by shifting 80,000 ha of low-efficiency rice production areas into maize production （2014-2015） and this area of production for maize is expected to increase to 150,000 ha by 2016-2020. Nevertheless, not all commercial maize hybrids could be suitable for rice-growing land in the Mekong Delta and a national project of hybrid maize development for Mekong Delta has been conducted since early 2014. In the project, yield trials of 20 maize hybrids, sourced from Vietnamese institutions and the private sector including Syngenta （NK67） and Dekalb （DK9901）, were sown in Dong Thap, Hau Giang and long An provinces situated in the Mekong Delta, in minor acid sulphate soils with a pH of 5.0-5.5. The trial included three replications in an Alpha lattice design conducted during spring-summer in 2014. The hybrids flowered at 50-52 d after planting and physiologically matured between 93-97 d after planting. This suggested they would be suitable for cropping systems, which was comprised of three seasons per year. To determine which hybrid is best suited for the region, researchers evaluated yield and ear characteristics. The average yield of the genotypes across locations was 52.03, 54.92 and 57.60 quintals/ha, respectively, and the heritability of genotypes in each location was 0.51, 0.81 and 0.61, respectively. The mean yield of DK9901 was 58.19 quintals/ha, ranking the 7th among 20 hybrids, and NK67 was 47.58 quintals/ha, ranking the 19th. The grand mean was 54.92 quintals/ha and heritability for all genotypes was 0.79. The highest yield was produced by the Southern seed company hybrid SSC474 （69.39 quintals/ha）, which yielded significantly more maize than DK9901 （58.19 quintals/ha） at P 〈 0.05, followed by VS71 from National Maize Research Institute （NMRI） at 63.52 quintals/ha, and LCH9A from NMRI at 63.39 quin

关键词： Maize (Zea mays L.) hybrid Mekong Delta rice-growing land yield trials.

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Pentanidium-Catalyzed Direct Assembly of Vicinal All-Carbon Quaternary Stereocenters through C(sp^(3))–C(sp^(3))Bond Formation

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CCS Chemistry 2021年第10期3卷 2192-2200页

作者： Xu Ban Yifan Fan Tuan-Khoa kha Richmond Lee Choon Wee Kee Zhiyong Jiang Choon-Hong Tan International Scientific and Technological Cooperation Base of Chiral Chemistry Henan UniversityKaifeng 475004 Division of Chemistry and Biological Chemistry Nanyang Technological UniversitySingapore 637371 School of Chemistry and Molecular Bioscience University of WollongongWollongongNSW 2522 Molecular Horizons University of WollongongWollongongNSW 2522 Process&Catalysis Research Institute of Chemical and Engineering SciencesSingapore 627899

The stereoselective construction of vicinal all-carbon quaternary stereocenters has long been a formidable synthetic *** asymmetric coupling of a tertiary carbon nucleophile with a tertiary carbon electrophile is themost straightforward approach,but it is sterically and energetically ***,we describe a catalytic asymmetric substitution,where racemic tertiary bromides coupled directly with racemic secondary or tertiary carbanion.

关键词： ion-paired catalyst asy mmetric substitu-tion SN2 substitution SN2X substitution all-carbon quaternary stere ocenters

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应用压力恢复测试法检测水和气的推进前沿

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油气田开发工程译丛 1992年第12期 13-17页

作者：赵钧 kha.,AAW

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电子束辐照对蓝莓的长效冷藏保鲜效果

电子束辐照对蓝莓的长效冷藏保鲜效果

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作者： NGUYeN XUAN kha 安徽农业大学

学位级别：硕士

蓝莓,杜鹃花科,越橘属,因其甜美的口味、丰富的营养成分、强大的保健功能,广受欢迎。由于皮质薄、果肉柔软多汁,采后呼吸代谢旺盛,蓝莓在常温(25℃±5℃)下放置2～4d,低温(2℃±2℃)下放置7～10d就失去商品价值,严重制约了蓝莓产业的发... 详细信息

蓝莓,杜鹃花科,越橘属,因其甜美的口味、丰富的营养成分、强大的保健功能,广受欢迎。由于皮质薄、果肉柔软多汁,采后呼吸代谢旺盛,蓝莓在常温(25℃±5℃)下放置2～4d,低温(2℃±2℃)下放置7～10d就失去商品价值,严重制约了蓝莓产业的发展。电子束辐照是一种物理加工方式,通过杀灭食物表面及内部的有害微生物、抑制生理变化,延长果实的保鲜期。本文通过设计不同的辐照剂量梯度 0.0kGy(未辐照为对照组)、1.0kGy、1.5kGy、2.0kGy、2.5kGy、3.0kGy,分析冷藏过程中蓝莓果实中的细菌、霉菌及酵母菌的杀灭效果,以及不同剂量电子束辐照对冷藏蓝莓果实贮藏品质、生理与功能特性的影响作用。1.1.0～3.0kGy剂量范围的电子束辐照处理,显著降低细菌、霉菌与酵母菌微生物的数量,并且与辐照剂量呈显著正相关关系。蓝莓中细菌、霉菌、酵母菌的D10值分别为 1.54 kGy、1.69 kGy、2.40 kGy。冷藏至 105 d,1.5～3.0 kGy 辐照蓝莓组微生物数量显著低于对照组,但是四个辐照组之间没有显著性差异。2.在整个冷藏期(105 d),辐照处理显著降低了蓝莓的腐烂率。贮藏末期,1.5～3.0kGy辐照组的失重率达到30%,但腐烂率低于8%,虽然失去鲜食价值,但依然具有加工价值。1.5～3.0kGy辐照组蓝莓保鲜期可达到60d,腐烂率低于5%,失重率15%左右。同时,各辐照处理组相比对照组,有效延缓蓝莓果皮的亮度(L值)下降、抑制果皮变色(a值与b值)。3.在贮藏前期,辐照处理对蓝莓的硬度没有显著性影响。贮藏至30～60d,2.0kGy辐照组果实硬度显著高于对照组。在贮藏后期,1.5～3.0kGy辐照组抑制了TSS和可溶性糖的降解,但对果实的pH值没有显著性影响。4.贮藏45d内,辐照处理组花青素和总酚含量显著高于对照组,尤其是1.5kGy辐照组花青素含量最高,3.0kGy辐照组总酚含量最高。各辐照处理组的DPPH自由清除率显著高于对照组,其中2.0kGy组效果最好。5.2.0～3.0kGy辐照处理显著提高了果实的多酚氧化酶(PPO)活,但1.0～1.5kGy的剂量对多酚氧化(PPO)酶活没有显著影响。在贮藏后期,1.5～2.0kGy辐照组的过氧化物酶(POD)活性显著高于对照组和其他辐照处理组;1.5～2.5kGy辐照组的局半乳糖醛酸酶(PG)活性,显著低于对照组;贮藏前期,1.5～2.5Gy辐照组的纤维素酶(Cx)活性显著低于对照组,延缓软化。综上所述,1.5kGy～2.0kGy剂量电子束辐照处理,能显著降低冷藏过程中蓝莓果实中的细菌、霉菌及酵母菌数量,蓝莓的品质及生理特性保持最佳,可延长蓝莓的保鲜期至60d,冷藏期90～105d。

关键词：蓝莓电子束辐照微生物冷藏保鲜

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