小方式下基于高压电网结构调整的新型电压控制方法研究

为避免部分电网在小方式下因感性补偿装置不足导致的母线电压越上限的情况,提出了一种基于城市110 k V高压配电网络结构调整的新型调压方法。本策略综合考虑了线路热稳、变压器容量和潮流断面传输功率的约束条件,借鉴中低压配网重构思想,通过改变原有110 k V电压等级变电站接线方式,从而调整全网电压的偏移率。该方法采用贡献率指标评估对应变电站接线方式改变对系统电压的影响,并根据计算结果对电网结构进行调整,避免了传统的启发式优化算法导致的计算速度慢,维数灾难等缺点。四川某地区电网实际算例显示,提出的电压调整方法可以有效地改善网内电压分布,具有简单易行的优点,在工程中具有广泛的应用前景。

湖北电网枯水期小方式典型日电压无功分析

根据湖北电网的特点,枯水期小负荷方式下湖北西部水电出力大幅减少,东部火电机组出力较大,由于系统电源出力及负荷的变化,导致系统电压的大幅波动,枯小方式下湖北电网电压偏高及电压波动的问题较突出。以2021年枯水期小方式典型日为例,以当日负荷最低点的潮流数据为基础,对2021年湖北电网枯小方式500 kV、220 kV两个电压等级的电压水平及无功潮流进行详细分析,并提出电压控制建议。

直流多落点系统控制敏感点挖掘技术研究

针对交直流相互作用引发的低频振荡模态的抑制问题,提出了一种基于单回直流对系统功率振荡灵敏度理论的控制敏感点挖掘技术。该技术的关键步骤在于应用Prony辨识技术得到系统关键振荡模态,以及采用TLS-ESPRIT算法筛选出参与因子较大的发电机组,从而能够通过检测不同直流调制下各模态强相关机组的转速变化,找到对系统关键振荡模态调节效果最有效的一回直流线路。以一个多落点系统为实例,设计小方式控制模块验证了该方法的有效性。

Field Experiment for the Effects of Rice Straw Returning and Seeding Pattern on Wheat Seedling Emergence and Grain Yield

In order to study the effect of rice straw returning and seeding patterns on seedling emergence and grain yield, field experiment was conducted to investi- gate the effects of straw mechanized returning and different seeding patterns on e- mergence rate, emergence uniformity and yield traits of wheat after rice. The results were as follows： in rice straw removal treatments, the emergence rate of mechani- cal seeding in drill was lower than that of mechanical uniform planting and manual broadcast sowing, which were 51.84%, 90.89% and 88.87%, respectively; the emer- gence uniformity of manual broadcast sowing was inferior to mechanical seeding in drill and mechanical uniform planting, which were 0.49, 0.26 and 0.23, respectively. As for the treatments with rice straw returning to the field, the emergence rate and emergence uniformity all decreased in the three seeding patterns, of which mechan- ical seeding in drill dropped markedly with emergence rate decreased by 36.54%. The emergence rate and emergence uniformity affected grain yield by affecting pan- icle, grains per spike and 1 000-grain weight. The grain yield for the treatment with rice straw removal was 6 091.34 kg/hm2, while that with rice straw returning to field was 6 476.20 kg/hm2, and both were higher than the yields of the other two seed- ing patterns. Therefore, mechanical uniform planting was？recommended for its higher emergence rate, better emergence uniformity, which was conductive to increase grain yield in wheat after rice production with rice straw returning to field.

湖北电网母线总阻抗计算的若干关键问题

结合多年来湖北电网母线总阻抗计算的经验,指出了整定计算软件中母线总阻抗计算功能模块必须考虑的若干关键问题。基于该思想开发的母线总阻抗计算软件模块已成功应用于湖北电网,取得了良好的应用效果。

Enhanced kernel minimum squared error algorithm and its application in face recognition

To improve the classification performance of the kernel minimum squared error（ KMSE）, an enhanced KMSE algorithm（ EKMSE） is proposed. It redefines the regular objective function by introducing a novel class label definition, and the relative class label matrix can be adaptively adjusted to the kernel matrix.Compared with the common methods, the newobjective function can enlarge the distance between different classes, which therefore yields better recognition rates. In addition, an iteration parameter searching technique is adopted to improve the computational efficiency. The extensive experiments on FERET and GT face databases illustrate the feasibility and efficiency of the proposed EKMSE. It outperforms the original MSE, KMSE,some KMSE improvement methods, and even the sparse representation-based techniques in face recognition, such as collaborate representation classification（ CRC）.

Effects of Sulfur Fertilizer Application Methods on Grain Protein Content During Filling Stage of Winter Wheat

[ Objective] The experiment aimed to provide a theoretical base of optimal cultivation management for the high yield and good quality and high efficiency of winter wheat. [ Method] The effects of two sulfur fertilizer application methods on dynamic changes of grain protein content and glutenin content of Yumai 49 and Yumai 66 during wheat grain filling stage were studied under the field conditions. [Result] Both the grain protein and glutenin content of two cultivars were increased by sulfur fertilizer, particularly, the effects on Yumai 49 were more significant.[ Conclusion] The grain content and glutenin content of different wheat cultivars could be increased by taking different sulfur fertilizer application methods.

Wavelet transform and gradient direction based feature extraction method for off-line handwritten Tibetan letter recognition

To improve the recognition accuracy of off-line handwritten Tibetan characters the local gradient direction histograms based on the wavelet transform are proposed as the recognition features.First for a Tibetan character sample image the first level approximation component of the Haar wavelet transform is calculated.Secondly the approximation component is partitioned into several equal-sized zones. Finally the gradient direction histograms of each zone are calculated and the local direction histograms of the approximation component are considered as the features of the character sample image.The proposed method is tested on the recently developed off-line Tibetan handwritten character sample database.The experimental results demonstrate the effectiveness and efficiency of the proposed feature extraction method.Furthermore compared with the detail components the approximation component contributes more to the recognition accuracy.

Effects of Planting and Irrigation Patterns on Water Consumption Characteristics and Dry Matter Production in Winter Wheat

[Objective] This study aimed to investigate the effects of different planting and irrigation patterns on water consumption characteristics and dry matter produc- tion and allocation of winter wheat. [Method] With high-yield winter wheat cultivar Jimai 22 as the experimental material, field experiment was conducted during 2008- 2010. A total of 3 planting patterns were designed, uniform row, wide-narrow row and furrow. Under each planting pattern, total four irrigation patterns were designed, no irrigation （Wo）, irrigation at jointing state （Wl）, irrigation at jointing and anthesis stages （W2） and irrigation at jointing, anthesis and milking stages （W3）, and the irri- gation amount per treatment was all 60 mm. [Result] Under the three planting pat- terns, with the increased irrigation amount, the total water consumption of the exper- imental field increased; the proportion of irrigation in the total water consumption in- creased, and that of soil water consumption in the total water consumption de- creased significantly. Compared with W0 treatment, various irrigation treatments sig- nificantly increased the post-anthesis dry matter accumulation in wheat plants; with the increased irrigation amount, the grain yield under the three planting patterns all increased, while the water use efficiency （WUE） decreased. Under the same irriga- tion conditions, compared with other two planting patterns, furrow planting increased the total water consumption of the experimental field, increased the proportion of soil water consumption in the total water consumption, and improved the WUE and wheat grain yield. [Conclusion] Under the experimental conditions, considering both wheat grain yield and WUE, furrow planting with moderately deficit irrigation at joint- ing and anthesis stages is more suitable for the winter wheat production in North China Plain.

A Multilayer Recurrent Fuzzy Neural Network for Accurate Dynamic System Modeling

A multilayer recurrent fuzzy neural network(MRFNN)is proposed for accurate dynamic system modeling.The proposed MRFNN has six layers combined with T-S fuzzy model.The recurrent structures are formed by local feedback connections in the membership layer and the rule layer.With these feedbacks,the fuzzy sets are time-varying and the temporal problem of dynamic system can be solved well.The parameters of MRFNN are learned by chaotic search(CS)and least square estimation(LSE)simultaneously,where CS is for tuning the premise parameters and LSE is for updating the consequent coefficients accordingly.Results of simulations show the proposed approach is effective for dynamic system modeling with high accuracy.

Effect of Tillage and Planting Methods on the Soil Properties, Grain Drill Performance, and Wheat Yield

The effect of conservation tillage methods and seeding machines on the soil physical properties, performance of grain drill, wheat yield, and wheat yield components was evaluated. The research was conducted in a split block experimental design with twelve treatments and four replications, and a local wheat variety （Shiraz） was planted in this study. Main plots were tillage methods including： （1） primary tillage using moldboard plow without moldboard; （2） primary tillage with disk harrow; and （3） primary tillage with chisel plow. Subplots were grain drill types including： （1） planting with Taka grain drill without furrower; （2） planting with Taka grain drill having furrower; （3） planting with Hamadan Machine Barzegar grain drill having furrower and runner opener; 4） planting with grain drill having ripple opener. Parameters including mean weight diameter of clods （MWD）, soil bulk density, uniformity of seed planting depth, seed distribution uniformity, seed emergence, crop yield, and crop yield components were measured. SAS software was used to analyze the collected data and the method of benefit to cost ratio was used to compare the treatments from the economic point of view. Results indicated that tillage method had no significant effect （P = 0.05） on the measured parameters. Plant per unit area, seed emergence, uniformity of seed planting depth, and MWD were significantly affected by the grain drill type （P 〈 0.05） while, the type of grain drill had no significant effect on the rest of measured parameters. Taka grain drill without furrower had the highest uniformity of planting depth and proper soil MWD, and grain drill with ripple opener had the highest seed emergence and plant per unit area. Interaction between tillage methods and grain drill types affected the soil MWD, seed emergence, and crop yield （P 〈 0.05） in such a way that the combination of primary tillage with disk harrow and planting with grain drill having ripple opener provided the highest crop yield.

Meshfree First-order System Least Squares

We prove convergence for a meshfree first-order system least squares(FOSLS) partition of unity finite element method(PUFEM).Essentially,by virtue of the partition of unity,local approximation gives rise to global approximation in H(div)∩H(curl). The FOSLS formulation yields local a posteriori error estimates to guide the judicious allotment of new degrees of freedom to enrich the initial point set in a meshfree dis- cretization.Preliminary numerical results are provided and remaining challenges are discussed.

Waste Minimization Through Process Integration and Multi-objective Optimization

By avoiding or reducing the production of waste, waste minimization is an effective approach to solve the pollution problem in chemical industry. Process integration supported by multi-objective optimization provides a framework for process design or process retrofit by simultaneously optimizing on the aspects of environment and economics. Multi-objective genetic algorithm is applied in this area as the solution approach for the multi-objective optimization problem.

Trophic ecology of small yellow croaker (Larimichthys polyactis Bleeker): stable carbon and nitrogen isotope evidence

The trophic ecology of the small yellow croaker （Larimichthys polyactis） was studied using stable isotope analyses. Samples were collected from July to September 2009 and 34 individuals from eight sites were examined for stable carbon and nitrogen isotopes. Stable carbon isotope ratios （~3C） ranged from -20.67 to -15.43, while stable nitrogen isotope ratios （~SN） ranged 9.18-12.23. The relationship between fi^3C and ~SN suggested high resource partitioning in the sampling area. Significant differences in stable isotope values among the eight sampling sites may be linked to environmental diversities involving various physical processes （such as ocean current, wind and tide） and different carbon sources. Furthermore, the stable isotope ratios may also explain the ontogenetic variability in diet and feeding, because δ13C and δ15N varied significantly with increasing body size. The findings are consistent with other studies on diet analyses in small yellow croaker. It was also demonstrated that stable isotope analysis could be used to estimate the trophic characters of small yellow croaker in feeding patterns and migrating habits.

Total embolization of the main splenic artery as a supplemental treatment modality for hypersplenism

AIM:To study the safety and feasibility of total embolization of the main splenic artery as a supplemental treatment modality for hypersplenism with thrombocytopenia or leukocytopenia accompanying liver cirrhosis.METHODS:Fifteen consecutive patients with hypersplenism due to cirrhosis were enrolled in this study from January 2006 to June 2010.All patients underwent total embolization of the main splenic artery.Clinical symptoms,white blood cell(WBC) and platelet(PLT) counts,splenic volume,and complications of the patients were recorded.The patients were followed up for 1 and 6 mo,and 1,2,3 years,respectively,after operation.RESULTS:Total embolization of the main splenic artery was technically successful in all patients.Minor complications occurred in 13 patients after the procedure,but no major complications were found.The WBC andPLT counts were significantly higher and the residual splenic volume was significantly lower 1 and 6 mo,and 1,2,3 years after the procedure than before the procedure(P < 0.01).Moreover,the residual splenic volume increased very slowly with the time after embolization.All patients were alive during the follow-up period.CONCLUSION:Total embolization of the main splenic artery is a safe and feasible procedure and may serve as a supplemental treatment modality for hypersplenism with thrombocytopenia or leukocytopenia accompanying liver cirrhosis.

Modeling on a Modified Feeding Mode of Simulated Moving Bed for Improving Productivity

A new feeding mode for a simulated moving bed(SMB) is proposed.The outlet stream from zone II is collected at regular intervals.The concentration of the solution is increased by dissolving raw materials and then fed to zone III as the feed stream during the next collection interval.In this feeding mode,the concentration of the stream fed to zone III is identical to that of original feed,while in a conventional SMB,the feed is diluted by mix-ing with the outlet stream of zone II before feeding to zone III.The new feeding mode increases the inlet concentra-tion of zone III.A modeling investigation shows that higher inlet concentration of zone III increases the height of concentration band in SMB,improving the separation performance significantly.In comparison with the traditonal feeding mode,the new feeding mode increases the productivity by 23.52%and decreases the solvent consumption by 22.56%,so as to increase the raffinate and extract concentrations by 53.17%and 20.38%,respectively.The col-lection interval for the outlet stream from zone II has no effect on the separation performance after reaching the steady state,so that the collection interval can be increased to make the operation more convenient.

Interpretation of Symbolism in Willa.Cather novel ＂A Lost Lady＂

＂ A Lost Lady＂ is at beginning of the 20th century, a important work of creation of a famous American writer Willa Cather, through a story that a woman in a social swirl in old age gradually fall and sink, it reflects the commercialization of human society and other traditional values and lifestyle impact and erosion, and the desire of mankind for a better civilization. Works use artistic symbolism to play a certain role in the development of the plot, the characters change shape and opposition figures to portray the psychological state.

Study on Negative Effects of Multimedia Teaching on Education in Middle and Primary Schools

In such an information age, multimedia teaching has changed into one of the most important educational ways in middle and primary schools. In contrast to traditional education, multimedia teaching owns numerous advantages. However, there are also a great number of shortcomings in it. In this paper, considering the current situation of education in middle and primary schools, the author carries out an analysis on the negative effects of multimedia teaching on education in middle and primary schools, and also proposes some personal suggestions, hopefully providing a reference for teaching personnel in middle and primary schools.

Russian Culture in Kazakh Prose

The article draws attention to the linguistic consciousness of a bilingual Kazakh writer D. Nakipov formed under the influence of Russian culture. The peculiar way of thinking about reality is fixed in a work of fiction by means of special speech techniques, verbal images of not only his native language culture, but the culture he grew up in.

Explore the impact of e-commerce network on development of regional economic

In the era of rapid development of the Intemet, people began to adapt to the huge growth of the Internet to facilitate people＇ s daily lives, people have been accustomed to staying at home and can easily enjoy the convenience and needs of life to achieve quick and easy lifestyle. The advent of the Internet age also become more virtual to business models, and now the development of enterprises has involved the application of e-commerce technology, the company＇ s business model combines network through electronic technology to some extent, and it made great adjustments and changes in order to deal with the new face of increasingly fierce competition in the market. Thus a new term： ＂E-commerce＂ is well known and accepted as more and more people. A regional economic development need of the residents＇ daily consumption is driven, so local governments need to focus on the various steady development of local small and medium enterprises. Therefore, the development of electronic commerce network technology can indirectly affect a region＇ s economic development. This paper discusses this issue.