A contour extraction algorithm for digital images based on water balloons snake model

Due to weak edges and low contrast areas in digital images, such as a left ventricle in Magnetic Resonance Imaging (MRI) images, a deformation curve may leak from the outer boundary when images are segmented using the traditional snake model. An improved algorithm based on the water balloons snake model is introduced to solve this problem. Firstly, the barycenter and the boundary shape area of the left ventricle in a digital MRI image are obtained through mathematical morphology. The left ventricular watershed line is obtained next using a watershed transform algorithm, which is taken as the initial deformation curve in a balloon snake model to capture the contour. Different snake models are tested to digitally tagged MRI images of left ventricles of small pigs. Contrast results indicate that the water balloons snake model can solve the leakage problem in traditional snake and balloon snake models. In addition, the processing speed is improved significantly.     

A new type of prestressed concrete hollow girder design for overcoming the typical diseases

This paper proposes a new type of prestressed concrete hollow girder based on the summaries of the current studies on longitudinal cracks and hinge cracks. The match prefabricated method is used with shear key at interface to solve the problem of hingle cracks, and the two-way prestressing strand techniques are used to assure the longitudinal load-bearing capacity and to prevent the emergence of longitudinal cracks because of pressure existing at the match interface. In order to reduce the temperature difference between the internal and external of the prestressed concrete hollow girder, drilling holes are carried out at the bottom slab of girder every distance. To ensure the adhesive effect between the girder and deck pavement, we designed grooves at the top slab of girders. The finite element analysis results of a design example show that the pressure stress of bottom slab of girder is about 2.58 MPa and 0.16 MPa, which are effective to avoid the appearance of longitudinal cracks and hinge cracks.     

Limitation and improvement of the equivalent capacity method for calculating the energy loss of distribution networks

Through the analysis of the equivalent resistance method, a limitation of the equivalent capacity method was presented. When the direction of power at the feeder source end was changing, the equivalent capacity method for handling small generations would produce a large power loss calculation error. An improved calculation method, one not based on a single equivalent resistance, was proposed. In this method, one day was divided into several periods (such as 24 h), so that the direction of power at the feeder source end for each period does not vary. The equivalent resistance and energy loss in each period were calculated. The sum of all energy losses provided the daily energy loss total. Numerical examples were used to verify the improved method.     

A Study on the Test Method for Post-tensioned Prestressed Concrete Frame

A creative test method for post-tensioned prestressed frame is presented in this paper. In the test, the stationary supports at the column base are simulated and the forces at the column base can be tested while the two column bases are not connected with concrete beam. The prestressed secondary moment and the weight-produced moment are established by adjusting the support device at the column base. In this paper, the necessary conditions of the method and the basic process are recommended. It is proved theoretically that the prestressed concrete frame built by this method is equivalent to that used in practice.     

内框架箱型混凝土结构施工活荷载实测分析

施工期早龄期钢筋混凝土结构与模板支撑系统组成临时承载体系为时变结构,其承担的荷载主要有新浇筑混凝土自重与包括施工人员和设备荷载以及混凝土浇筑时产生的冲击和振捣荷载在内的施工活荷载。将多层连续施工时变结构体系模拟成一组弹性支撑连续板,根据该模型分析了施工期现浇钢筋混凝土结构的受力特性。根据现场实测数据,以构件有效承载面积为统计对象,计算了混凝土施工荷载的统计参量,并参考相关研究成果,以95%的置信度对施工期活荷载标准值进行反演,建议施工活荷载标准值取2.5 kN/m 2。     

模式识别的斜拉桥损伤诊断动力指纹与识别算法

为有效并准确诊断出斜拉桥损伤,对基于模式识别的斜拉桥损伤诊断方法进行了研究。选取易于测试出的低阶模态频率和部分关键点竖向振型数据为动力指纹,无需模态扩展或模型缩聚。研究并采用全因子设计进行动力指纹库的创建,可精确评估设定的损伤因子及其交互作用对损伤识别结果的影响。设计并增加了带随机误差的动力指纹库样本集。编制了基于Matlab的模式识别的多种算法,重点研究了精确度高的多层感知器识别算法及其提高该算法预测准确率的装袋集成算法。最后给出一座单塔双跨双索面斜拉桥的多种识别算法的损伤诊断过程和结果,得到一种可包容测试随机误差的高精确度斜拉桥损伤诊断评估模型。     

基于Adaboost算法的输电线路舞动预警方法

输电线路舞动是目前尚未被全面准确认识的世界性难题,已严重威胁输电系统的安全稳定运行。文章分析影响舞动的外界气象环境因素,并在此基础上提出一种基于Adaboost集成学习算法的输电线舞动预警方法。采用基于Gini指标的决策桩作为弱分类器,通过对多个弱分类器的训练及加权求和,输出舞动预测结果及其置信度,可为电网运维人员提供决策支撑。最后,使用历史数据进行验证性实验,结果证明了所提方法的有效性。     

Simulation of the constant modulus blind equilibrium algorithm with variable step size based on the mean square error

The mathematic models and basic theory of constant modulus algorithm (CMA) for blind channel equalization are introduced. An improved algorithm with variable step size is proposed based on CMA. The improved algorithm uses the mean square error (MSE) to obtain the new variable step size to solve the contradiction between the convergence rate and accuracy in traditional CMA with fixed step. To smooth the MSE learning curve for easy comparison, an ensemble average technique is used to analyze the performance of convergence with different step sizes. The theoretical analysis and the simulation results show that the improved algorithm is superior to the traditional constant modulus(CM) in terms of convergence speed and residual error.     

北疆高产棉花根系构型与动态建成的研究

在大田条件下,研究棉花根系构型分布和动态建成结果表明,北疆高产棉花根系生物量的积累呈S型曲线,其中线性增长期从6月下旬(盛蕾期)至7月下旬(盛花期),较地上部相应时期早约10d。随种植密度的增大,根系生长率下降、快速生长期提前。根系在土壤中的下伸过程呈S型曲线,构型分布符合Y＝Ae-Bx指数方程,有52．4％、65．8％和73．3％以上的根量分别集中在地表20cm、30cm和40cm深的土层内,80．6％以上的根量集中在植株行间两侧0～15cm土体内。与内地棉区相比,北疆棉花根量小,但生产力更高。     

Experiments on the pretreatment of corn stover for biogas production based on dry fermentation

Microbial pretreatment can enhance biogas production from corn stover through solid-state anaerobic digestion, but the price of microbial strains is high. Stack-pretreatment is introduced to gain higher biogas production from corn stover through solid-state anaerobic digestion. The purpose is to find the effects of naturally microbial pretreatment on stalk lignin, cellulose and hemicellulose degradation, and biogas production. The result indicates that the corn straws which has been stack-pretreated for 20 days decreases of the content of the middle corn straws cellulose, hemi-cellulose and lignin by 5.8%, 16.8% and 5.7% respectively lower than those of untreated samples. The highest cumulative biogas yield for 60-day digestion is obtained in the group that the mass ratio of corn stover and cattle dung is 1∶1, which is 24.4% higher than that of untreated corn stover mixed with cattle dung with the same mass ratio. When the mass ratio of corn stover and slug is 1∶1, the cumulative biogas is 23.27% higher than that of untreated corn stover with slug.     

A new method for evaluation of the resistance to rice kernel cracking based on moisture absorption in brown rice under controlled conditions

We developed and evaluated the effectiveness of a new method to detect differences among rice cultivars in their resistance to kernel cracking. The method induces kernel cracking under laboratory controlled condition by moisture absorption to brown rice. The optimal moisture absorption conditions were determined using two japonica cultivars, ‘Nipponbare’ as a cracking-resistant cultivar and ‘Yamahikari’ as a cracking-susceptible cultivar: 12% initial moisture content of the brown rice, a temperature of 25°C, a duration of 5 h, and only a single absorption treatment. We then evaluated the effectiveness of these conditions using 12 japonica cultivars. The proportion of cracked kernels was significantly correlated with the mean 10-day maximum temperature after heading. In addition, the correlation between the proportions of cracked kernels in the 2 years of the study was higher than that for values obtained using the traditional late harvest method. The new moisture absorption method could stably evaluate the resistance to kernel cracking, and will help breeders to develop future cultivars with less cracking of the kernels.     

基于土地氮磷承载力的区域畜禽养殖总量控制研究

畜禽粪便已经对我国的水环境形成了巨大的污染威胁。针对某一区域的畜禽粪便污染,基于从源头减少畜禽粪便产生较为困难、现有处理技术对畜禽粪便氮磷去除效果有限、畜禽粪便或者其处理剩余物难以长距离转移、土地对氮磷的承载力有限等基本条件,从理论上提出了区域畜禽养殖应进行总量控制的基本思路。基于耕地面积对我国及各省畜禽养殖的允许总量进行了初步估算,并与实际总量进行了比较分析。结果表明：2007年,以氮素为基准,全国畜禽养殖允许总量为25.03亿头猪当量,总量使用率为64.39%;以磷素为基准,全国畜禽养殖允许总量为13.68亿头猪当量,总量使用率为100.20%。分省来看,以氮素和磷素为基准,分别有5个和17个省份的实际总量超过其允许总量。因此,从畜禽粪便污染控制角度来看,对部分省份以及重点区域进行畜禽养殖总量控制非常紧迫。     

甜菜种,肥分层机播技术研究

本文讨论了甜菜的种、肥分层机播技术.在同等条件下使用该项技术,甜菜生育前期的生长势显著增强,与种、肥混播的耧种甜菜相比,株高、叶片数、叶面积和叶面积指数等四项指标均有较大幅度提高,定植时株距的变异系数明显小于耧播;甜菜块根产量增加15%以上,含糖率略有提高.     

优质早稻T78优2155综合高产栽培技术研究

T78优2155是福建省三明市农科所育成的杂交早稻新组合,已通过福建、广西、广东省品种审定委员会的审定。为了探讨其高产栽培技术,运用最优设计,对优质早稻T78优2155进行移栽叶龄、密度和施N量3项栽培措施研究。建立产量与3项栽培措施的回归模型。分析了栽培措施对产量的影响,结果表明,3项措施对产量都有影响。并经微机模拟筛选出高产的技术措施是：4.0~5.2叶移栽,每公顷插16.5~31万丛,施纯N量155~212kg。     

A specific PCR assay for resistance to biotypes 1 and 2 of the rosy leaf curling aphid in apple based on an RFLP marker closely linked to the Sd1 gene

This report describes the conversion of a restriction fragment length polymorphism (RFLP) marker (the 2B12a locus). linked to the Sd₁ aphid resistance gene, to a polymerase chain reaction (PCR) based marker. A section of the 2BI2 probe was sequenced and two primers were designed lo amplify this sequence in the cultivars‘Prima’and‘Fiesta’: all the amplification products were the same size. After sequencing. two specific 24-mer oligonueleotides were synthesized (DdARM-5¹ and DdAR.M-3²) to exploit a single base-pair difference. These primers were used to screen 44 plants from the‘Prima’x‘Fiesta’family and generated a single amplification product (196bp). in approximately half of the seedlings, which was linked to the resistance gene Sd₁,. The DdARM primer combination was used to evaluate a range of apple cultivars and selections, including some varieties derived from‘Cox’and alternative sources of resistance reported in the literature. In parallel with this work, the phenotypic response of the same genotypes was either confirmed or determined in replicated glasshouse tests. The sequence characterized amplified regions (.SCAR) marker was amplified in all the resistant plants, with the exception of‘Northern Spy’and 3760 (the sources of Sd₂ and Sd₃ resistance, respectively), but never in the susceptible plants. The possible role of this marker in a marker-assisted breeding strategy, and its compatibility with a SCAR marker linked to the I, gene for resistance to apple scab. is discussed.     

“玉米生产管理智能决策系统”推广模式研究

摘 要：【研究目的】探讨“玉米生产管理智能决策系统”适宜推广模式,加快农业科技成果转化步伐;【方法】将实证法与文献法相结合,将农业科技成果推广理论与实践相结合进行定性分析;【结果】在借鉴国内外农业信息技术成功推广模式的基础上,分别对“农业协会”、“涉农公司”及“政府”作为“玉米生产管理智能决策系统”推广主体进行可行性分析;【结论】结果表明“政府+农户”为“玉米生产管理智能决策系统”最适宜推广模式。     

沿黄稻麦区水稻生长和氮素利用与土壤透水性的关系

采用^15N示踪和模拟土柱技术，对不同透水性土壤施用氮肥后水稻生育和氮肥利用率进行了研究。结果表明:土壤透水速率以20－30mm/d对水稻生育最为有利，完全不渗漏和透水速率超过40mm/d时，水稻分蘖明显减少，收获期干物质积累和子实产量仅为适宜透水率时的66．7％－93．4％和65．2％－93．8％。土壤透水性强烈影响水稻对氮肥的利用效率。土壤透水率在20－30mm/d时，水稻对氮的利用率超过60％，而不透水土壤和严重渗漏土壤的水稻对氮肥利用率仅为32．65－44．1％，损失率达30．8％－46．0％。稻作期间田面水层和0－5cm土层pH与土壤透水率呈负相关，排水不良易引起氮挥发。日渗漏20－30mm可作为沿黄高产稻麦田培育的定量指标。