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Analysis on Phase Arrangement and Transposition Modes for UHV DC and Double-circuit EHV AC Transmission Line Built on the Same Tower

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高电压技术 2012年第12期38卷 3133-3139页

作者： sima Wenxia ZHOU Yuan YUAN Tao YANG Qing SUN Shujie Gilles Tremouille State Key Laboratory of Power Transmission Equipment &System Security and New Technology Chongqing University Chongqing 400030China ALSTOM Grid Technology Center Shanghai 201114 China

For AC and DC hybrid transmission lines, the arrangement and transposition modes of AC conductors not only affect the unbalance factor of AC lines, but also influence the bias current of DC converter transformers by AC and DC coupling. Excessive bias current will influence the normal operation of converter transformers, thus the optimal AC phase arrangement and transposition mode of hybrid lines was studied to minimize the coupling effect between AC and DC lines to fit the requirements on both aspects. Based on the parameters of the Ximeng-Shanghai project in China, a detailed simulation model of the DC converter station and the hybrid transmission line with double-circuit AC 500 kV transmission lines and DC ± 800 kV transmission lines were presented in the software PSCAD-EMTDC, and the coupling effects of the hybrid transmission lines were elucidated. The fundamental frequency components of DC poles with different operation conditions, arrangements of conductors and operation modes were analyzed,and the effective arrangement and transposition limiting the fundamental frequency current component of the DC line were compared. Simulation results show that AC operating conditions can affect DC induced components while the DC system operation mode has no apparent effect. With compact arrangement and inconsistent transposition of AC lines, the fundamental frequency component on DC lines can be reduced effectively; the three-transposed mode within the hybrid line is the optimal layout scheme, considering both the requirements of DC bias current and AC unbalance degree.

关键词： 500千伏输电线路特高压直流换位方式同塔双回交流直流换流变压器双回路交直流混合

Simulation Analysis on Lightning Accident of ± 500 kV DC Transmission Line Based on ATP-EMTP

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高电压技术 2009年第4期35卷 802-808页

作者： FU Jin sima Wen-xia YANG Qing YANG Li-bin LI Zhi-tai State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing 400044 China Yangjiaping Power Supply Bureau Chongqing 400051 China Guangdong Electric Power Design Institute Guangzhou 510600 China

This paper calculates and researches on lightning accident of ±500 kV Xing-An DC transmission line in Guangdong based on ATP-EMTP and the simulation calculation model of the HVDC has been constructed. The results show that: when a lightning current strikes to the positive polar conductor of double circuit transmission line and the flashover of insulator strings occurs, as the over-voltage wave propagating along the lines due to the coupling effect between the conductors, the grounding electrode lines would produce the coupling voltage wave, which makes the flashover of the insulator strings occur at the different place along the grounding electrode lines, the un- balanced current of the grounding polar line is produced due to the insulator strings flashover and the unbalanced current exists for a long time, when the unbalanced current is up to the locking condition, the negative polar conductor is locked and the double-pole block fault occurs. In the paper, some effective measures are given to prevent this accident.

关键词：高压电技术闪电意外事故传输线

Innovative agricultural extension value chain-based models for smallholder African farmers

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Frontiers of Agricultural Science and Engineering 2020年第4期7卷 418-426页

作者： Bidjokazo FOFANA Leonides HALOS-KIM Mercy AKEREDOLU Ande OKIROR Kebba sima Deola NAIBAKELAO Mel OLUOCH Fumiko ISEKI Sasakawa Africa Association Gurd ShollaDaminarof BuildingAddis Ababa 1000Ethiopia Sasakawa Africa Association Sasakawa Peace Foundation BuildingTokyo 105-0001Japan

The value chain extension strategy of Sasakawa Africa Association focuses on improving the capacity of national agricultural extension systems and follows various thematic areas along the value chain to address key challenges accountable for low income households and poverty in *** learning platform is a model designed to increase crop productivity and encompasses demonstration plots where technological packages demonstrated significantly outperformed other technology plots in crop productivity and average profit ***-oriented production,postharvest and trading centers are value adding models designed to improve the effectiveness of extension and adoption of postharvest and agricultural processing technologies by *** use of the above along with necessary capacity building has facilitated the development of profitable business linkages of smallholder farmers with financial institutions and reliable market *** community association trader-trainer model is a marketoriented business approach applied in combination with other extension *** 2018,297 community-based commodity association trader-trainers were mobilized and capacitated to improve farmer group dynamics and developed collective input and output access and cluster aggregation centers at community level where various agricultural produces were mobilized and collectively aggregated,and valued at about 3.9 million *** supervised enterprise project model is an innovative agricultural extension model developed along with above models for capacity development of extension agents and transfer of technologies to smallholder *** 6000 supervised enterprise projects have been introduced into 27 universities in 12 African countries for training front-line extension officers and extension delivery to farming communities.

关键词： crop productivity extension farmer grain yield income model

Understanding Semiconductor Devices

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基于双向解剖的选择性保留胃网膜右血管第一分支在腹腔镜胃癌保留幽门手术中的可行性分析

2000年

作者： Dimitrijev, sima

ISBN: (纸本)9780195131864

Understanding semiconductor devices, as the building blocks of electronic circuits, is clearly of fundamental importance. In response to this challenge, this text, suitable for an advanced undergraduate or early graduate level course, is written to achieve the following goals: 1.)To meet the students' need to understand with: a)intuitive explanations of the underlying scientific concepts, b)explained fundamental equations, as opposed to using mathematics to explain physical phenomena, c)explained energy-band diagrams to provide rigorous and powerful presentations, which are easy to understand through an analogy with balls on a solid surface and bubbles in water, d)intriguing review questions, and a comprehensive set of worked out examples and problems. 2.)To provide a vertical (electronics-to-physics) hierarchy and a lateral (in terms of contents) flexibility. The electronics-to-physics approach motivates the students to learn the underlying scientific concepts and mathematical models by providing appropriate context and a continuous progression from the common-sense towards more abstract concepts. 3.) To provide CAD "nuts and bolts" with a small SPICE simulator widely used for computer-aided design of electronic circuits. The SPICE contents of this book provide a unique reference and pedagogical tools including: a)tabular presentations of the equations used as device models, b)hierarchically classified and explained SPICE parameters, c)case by case description of parameter measurement techniques, d)computer-based exercises that illustrate the effects of individual SPICE parameters on device and circuits characteristics. 4.)To provide links between the theoretical principles and real-life issues. The following points illustrate the level of integration achieved in this book: a)The device descriptions develop from application concepts (basic circuits). The underlying scientific concepts are "discovered" as needed. The introductions of particular device effects are ex

关键词： Integrated circuits

来源：畅想之星图书光盘版（南... 评论

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中华胃肠外科杂志 2024年第8期27卷 840-845页

作者：叶泽耀俞鹏飞曹阳柴腾蛟张斌忠司马军王兵江智辉余平元吴伟星杜义安浙江省肿瘤医院胃外科杭州310022 嘉兴二院胃肠外科嘉兴314051 杭州市红十字会医院胃肠外科杭州310030 温州医科大学温州325035

目的:探讨基于双向解剖的选择性保留胃网膜右血管第一分支,在腹腔镜胃癌保留幽门手术(LPPG)中的安全性与可行性。方法:采用描述性病例系列研究方法。回顾性收集自2018年2月至2023年8月期间浙江省肿瘤医院胃外科(28例)、嘉兴二院胃肠外... 详细信息

目的:探讨基于双向解剖的选择性保留胃网膜右血管第一分支,在腹腔镜胃癌保留幽门手术(LPPG)中的安全性与可行性。方法:采用描述性病例系列研究方法。回顾性收集自2018年2月至2023年8月期间浙江省肿瘤医院胃外科(28例)、嘉兴二院胃肠外科(1例)和杭州红十字会医院胃肠外科(1例)收治,并根据胃网膜右血管及幽门下血管在幽门袖的分布情况而行选择性保留胃网膜右血管第一分支LPPG治疗的30例胃中部早期胃癌患者临床资料。主要观察:(1)术中保留胃网膜右血管第一分支情况;(2)整体手术情况;(3)术后造影和内镜检查所见。结果:30例患者均成功实施选择性保留胃网膜右血管第一分支的LPPG手术。手术时间(244.3±29.3)min;中位术中出血量50(20~200)ml;中位肿瘤最大径1.2(0.5~3.6)cm,淋巴结清扫数量(32.3±11.6)枚;中位阳性淋巴结0(0~6)枚;清扫No.6淋巴结(5.1±1.5)枚;术后恢复进食时间(5.2±0.5)d;术后住院时间(8.4±3.4)d;术后病理T分期T1a、T1b和T2分别有14、10和6例;30例患者分别于术后5 d(28例)和9 d(2例)造影,提示小肠显影良好;无胃排空延迟病例,1例(3.3%)出现腹腔感染,保守治疗后痊愈。结论:选择性保留胃网膜右血管分支在LLPG治疗胃中部早期胃癌中安全可行。

关键词：胃肿瘤,早期腹腔镜保留幽门胃切除术双向解剖选择性保留胃网膜右血管第一分支胃排空延迟

Synthesis of corrected multi-wavelength spectrometers for atmospheric trace gases

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Chinese Optics Letters 2009年第5期7卷 361-363页

作者： Hikmat H.Asadov Islam M.Mirzabalayev Davud Z.Aliyev Javid A.Agayev sima R.Azimova Nabi A.Nabiyev Sevinj N.Abdullayeva Azerbaijan National Aerospace Agency Azerbaijan State Oil Academy

The method for synthesis of corrected three-wavelengths spectrometers for trace gas components of atmo- sphere on the basis of development of mathematical model has been suggested. The classification table for possible structures of corrected spectrometers is considered. The synthesis allows to reveal some new variants for development of three-wavelength spectrometers for trace gas components of atmosphere. For experimental checkup of achieved theoretical results, a laboratory pattern of three-wavelength spectrome- ter is developed and tested.

关键词： Synthesis of corrected multi-wavelength spectrometers for atmospheric trace gases

Inoperable esophageal cancer and outcome of palliative care

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World Journal of Gastroenterology 2008年第23期14卷 3725-3728页

作者： sima Besharat Ali Jabbari Shahryar Semnani Abbasali Keshtkar Jeran Marjani Abbasali Keshtkar Jeran MarjaniGolestan University of Medical SciencesGolestan Research Center of Gastroenterology and HepatologyGorgan 49177-65181Iran

AIM:To determine the outcome of esophageal cancer patients referred for palliative care,in Gorgan and Gonbad gastrointestinal clinics,northeast of Iran. METHODS:This cross-sectional study was done on inoperable esophageal cancer cases referred to gastrointestinal clinics in Gorgan and Gonbad city(2005-2006) . Demographic data were collected during the procedure and cases were followed up every one month. Improvement proportion was calculated with 95% confidence interval,to determine the rate of improvement. Survival analysis and Kaplan-Meier methods were used to estimate the duration of palliative care effectiveness. RESULTS:We recruited 39 cases into the study. Squamous cell carcinoma was the most prevalent(92.3%) . The middle third of the esophagus was involved predominantly(51.3%) . Dilation was the most preferred method(89.7%) and stenting was done in 4 cases. Decreasing dysphagia score was not related to palliation method or pathology type of carcinoma. Age of the patients was significantly related to the improvement of dysphagia score. Mean survival time was 137.6 d and median was 103 d. CONCLUSION:Results of this study showed a low survival rate after palliative care in esophageal cancer cases despite dysphagia scores' improvement after dilating or stenting.

关键词： Esophageal cancer Palliative care Survival Dysphagia Iran

Comparative study of electrical characteristics for n-type 4H–SiC planar and trench MOS capacitors annealed in ambient NO

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Chinese Physics B 2017年第10期26卷 404-410页

作者：申占伟张峰 sima Dimitrijev 韩吉胜闫果果温正欣赵万顺王雷刘兴昉孙国胜曾一平 Key Laboratory of Semiconductor Material Sciences Institute of Semiconductors University of Chinese Academy of Sciences College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Queensland Micro- and Nano-technology Center Griffith University

The interface properties and electrical characteristics of the n-type 4H-SiC planar and trench metal-oxide-semiconductor （MOS） capacitors are investigated by measuring the capacitance voltage and current voltage. The flat-band voltage and interface state density are evaluated by the quasi-static method. It is not effective on further improving the interface properties annealing at 1250 ℃ in NO ambient for above 1 h due to the increasing interface shallow and fast states. These shallow states reduce the effective positive fixed charge density in the oxide. For the vertical MOS capacitors on the （1120） and （1100） faces, the interface state density can be reduced by approximately one order of magnitude, in comparison to the result of the planar MOS capacitors on the （0001） face under the same NO annealing condition. In addition, it is found that Fowler-Nordheim tunneling current occurs at an oxide electric field of 7 MV/cm for the planar MOS device. However, Poole-Frenkel conduction current occurs at a lower electric field of 4 MV/cm for the trench MOS capacitor. This is due to the local field crowded at the trench corner severely causing the electrons to be early captured at or emitted from the SiO2/SiC interface. These results provide a reference for an in-depth understanding of the mobility-limiting factors and long term reliability of the trench and planar SiO2/SiC interfaces.

关键词： 4H-SiC metal-oxide-semiconductor capacitors trench interface states nitric oxide annealing

Clustering Color Image Segmentation Based on Maximum Entropy

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Clustering Color Image Segmentation Based on Maximum Entropy