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.     

An aeroelastic model design of ultra high voltage power transmission line systems

We present an aeroelastic model design and method creation based on the case of an ±800 kV ultra high voltage (UHV) power transmission line from Xiang Jiaba to Shanghai, P. R. Chin, Both the centralized and discreted stiffness modeling methods are unsuitable for tower aeroelastic modeling. Taking these stiffness and aerodynamic characteristics into account, we introduce a new method to create an aeroelastic model that includes a semi rigid model segment and U shaped springs. Because the span of this transmission line is too long to fit within the wind tunnel in the same proportions as the tower, the proportions of the line model is condensed further. Aeroelastic test requirements can be satisfied by comparing theoretical analysis and actual measurements of the system model dynamics.     

Influence of fine aggregate on initial shrinkage of high performance concrete

The type and percentage of sand affect the gradation of coarse fine aggregate and the amount of spare mortar in concrete, which further affects the resistance of fresh concrete to initial plastic shrinkage. Taking into account the engineering characteristics of sand in the area of Chongqing, P. R. China, three fine aggregates composed of superfine, medium, mixed and manufactured sand, are used to prepare high performance concrete (HPC). The effects of these three fine aggregates on initial plastic shrinkage crack are investigated. The results show that the HPC prepared with superfine sand possesses a higher initial shrinkage value than HPC prepared with mixed or medium sand. An optimal sand percentage is necessary to reduce the initial shrinkage cracking of HPC prepared with mixed or medium sand.     

微细铣削表面粗糙度预测与试验

分别采用正交试验回归分析法和基于正交旋转组合设计的二次响应曲面法(RSM)建立了微细铣削表面粗糙度预测模型,并在微小型车铣中心上对硬铝合金进行了试验研究,分析了铣削参数对表面粗糙度的影响.分别对两种预测模型进行了显著性检验并进行对比分析后发现:二阶响应曲面法的预测精度明显优于正交回归分析法.根据二次响应曲面法的试验结果,对回归方程中的回归系数进行了显著性检验,得出了铣削参数影响表面粗糙度的线性效应、二次效应和交互效应的显著性并进行了排序.试验结果表明:在试验采用的工艺参数范围内,对微细铣削表面粗糙度影响重要程度依次是铣削速度、每齿进给量、切削深度.     

基于远程监控的农业气象自动采集系统设计

针对传统农业气象观测和当前传感器技术系统、方法存在的不足,设计了一套基于远程监控的农业气象自动采集系统,其硬件设备由农田小气候信息采集前端、视频图像信息采集前端、数据采集装置、数据传输装置和供电设备组成。该系统实现了农田小气候和视频图像信息参数采集与传输的高度集成,自动采集降水量、气温、空气湿度、风速、风向、光合有效辐射、土壤温度、土壤湿度和农作物视频图像信息,并通过远程客户端软件实现各要素信息的实时动态显示和远程监控。通过在郑州市、鹤壁市、温江市和荆州市开展的采集试验和系统试运行表明,系统显示出较好的稳定性,农田小气候和视频图像要素数据的采集、传输、动态实时显示与远程监控等各项功能均可满足各级用户需求。     

导向管喷动床中煤和稻秸粒混料的流动特性试验

将导向管喷动床改进为煤粒和稻秸粒混料气化设备,通过导向管喷动床内进行的稻秸粒与煤粒混合物料冷态流动特性试验,给出喷动的流体力学条件。研究了床层压降随表观风速的变化规律,稻秸粒和煤粒混合比例、喷口直径和导向管喷口间距3因素对床层压降与表观风速关系曲线的影响以及对物料循环速率与风量关系曲线的影响。进行了3因素12拟水平的均匀设计试验,采用SPSS软件进行回归分析,分别得到了物料循环速率、单位床高压降及单位有效功率的物料循环速率3个因变量各自与稻秸粒和煤粒混合比例、导向管喷口间距及喷口直径3个自变量之间关系的多元回归方程,用于预测稻秸煤粒混料在导向管喷动床中喷动时的流体力学参数。     

农产品贮藏设施温控仪表温度漂移控制方法

选择3种具有代表性的贮藏设施通用温控仪表,检测其温度漂移幅度和方向。根据仪表电路原理并结合测试,进行了针对性电路改进,使温控仪表温漂误差幅度由3.5℃下降到0.3℃,贮藏环境温度波动幅度由5.3℃下降到1.4℃。试验筛选出3种简易温度补偿法,可在不改造仪表电路的前提下抑制温漂。     

面向预制食品溯源的隐私数据加密共享方法研究

随着区块链技术在食品溯源领域的发展,预制食品的质量安全得到了有效保障。然而,预制食品上下游生产加工环节众多的产业特点,使溯源变得困难。在溯源的同时安全共享食谱、秘方等隐私数据,使供应链更好地协同生产则十分重要。为解决上述问题,提出了一种面向预制食品溯源的门限代理重加密(Threshold proxy re-encryption)隐私数据共享的方法,设计了一条预制食品溯源区块链和追溯生产批号关联相关溯源数据,确保数据的真实可信。使用门限代理重加密,预制食品生产商通过门限代理重加密将研发的食谱加密为初加密密文,同时在本地生成重加密密钥,将初加密密文与重加密密钥上传至预制食品溯源区块链中;第三方半诚实服务商将从区块链上获取的重加密材料进行重加密生成重加密密文,将重加密密文上传至区块链;监管部门等数据访问者则使用自身私钥将从区块链上获取的重加密密文进行重加密解密,实现隐私数据在溯源区块链上的安全共享。该方法基于Hyperledger Fabric,搭建了一个预制食品溯源区块链原型系统进行测试。测试结果表明,所提出的面向预制食品溯源的隐私数据加密共享方法在隐私数据共享方面与常用的数据加密共享方法相比计算开销较低。数据上链、公开数据查询、隐私数据查询的平均时延分别为1.4738、63.9、59.9ms,系统性能良好。实验结果表明,提出的方法达到了供应链隐私数据安全共享的目的,确保了商业机密和知识产权的安全共享,对预制食品行业发展和食品安全提升具有参考价值。     

我国艺术健身类民族传统体育项目类别及文化特征研究

运用文献资料、专家访谈、逻辑推理等方法,归纳整理了艺术健身类民族传统体育项目的内涵、分类体系及文化特征等。认为艺术健身类民族传统体育项目可分为舞耍型、舞蹈型、秧歌型、装扮型、鼓器型和道具型六种类型，其文化特征具有民俗地域性、文体交融性、健康娱乐性、竞技体验性的特点。     

不同耕作覆盖措施下延收对春玉米产量的影响

【目的】研究延收对春玉米籽粒产量、千粒质量、灌浆速率、光温资源利用及植株器官干物质运移的影响,为玉米延收增产提供依据。【方法】以玉米"金赛6850"为材料,分别设传统耕作、传统耕作+秸秆覆盖、传统耕作+地膜覆盖、免耕+秸秆覆盖、免耕+地膜覆盖5个处理延期收获(习惯收获后,每隔5d为1个收获期),测定在不同耕作覆盖措施下延收对玉米千粒质量和产量的影响。【结果】适时延收,玉米千粒质量和产量增加显著,延收15d,传统耕作千粒质量平均日增3.59g,产量增加1 334.7kg/hm2,灌浆速率为1.7mg/(g.d);延长收获提高了光温资源的有效利用,延收15d,秸秆覆盖和地膜覆盖的有效积温分别增加了180.33和154.98℃,日照时数分别增加53.90和23.30h,植株干物质向籽粒中运移量以传统耕作最多,达10.06g,叶和茎秆的干物质对籽粒增重的贡献率较高。【结论】玉米适时延收具有明显的增产效果,但增产幅度因耕作和覆盖方式不同而有显著差异。