Structural Strength Study of Switching Cam Profile VVT Mechanism

The switching cam profile variable valve timing(VVT) mechanism is able to control valve lifting and timing system through higher and lower intake rockers at different engine speed.In this paper,multi-body dynamics and the(finite) element method(FEM) analysis method were combined to study the VVT mechanism.The analysis results indicate that intake rockers satisfy for design requirements and the dimensional discrepancy of the switching piston little(affects) on the VVT mechanism performance.     

Factors affecting haploid production in wheat using the Hordeum bulbosum system. 2. The effect of the timing of pollination

Summary The effect of manipulating the timing of pollination on the fertilization frequency in wheat × tetraploid Hordeum bulbosum hybridizations was investigated as a possible means of overcoming varietal incompatibility in this cross. Pre- and post-anthesis pollinations were made on previously identified highly crossable and poorly crossable wheat genotypes and the stage of development of the individual florets at pollination was expressed in days from anthesis units.In both crossable and non-crossable wheat genotypes, a significant negative linear relationship was observed between floret age and fertilization frequency. The magnitude of the response of early pollination was dependent on the number of alleles for non-crossability present at the Kr loci. The non-crossable cultivar Highbury, possessing more than one allele for incompatibility, showed a slight response. The greatest response was shown by the highly crossable cultivar Chinese Spring, possessing alleles for crossability at all Kr loci. The single chromosome substitution line, Chinese Spring (Hope 5B), possessing the most potent allele for non-crossability, Kr ₁, showed an intermediate response. The H. bulbosum genotype had no effect on the magnitude of this response, influencing only the mean fertilization frequency.     

Salicylic Acid–Induced Salinity Redressal in Hydroponically Grown Strawberry

The present study was conducted to evaluate shoot and root mineral composition of salt-stressed Selva strawberry under application timing of salicylic acid (SA). Treatments included plants sprayed with 0.5 or 1 mM SA, plants exposed to 40 mM sodium chloride (NaCl), and plants sprayed with 0.5 or 1 mM SA 1 week before, simultaneously, or after initiation of 40 mM salinity. Results indicated that under saline conditions, sodium (Na) and chloride (Cl) contents increased along with decrease in nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) in shoot and root of plants. In plants treated with SA at 1 mM concentration, 1 week before salinity application, root Mg and shoot Ca were greater in comparison to salt-stressed plants treated with the same SA concentration 1 week after their exposure to salt stress. Thus, earlier SA application appears to be a better strategy for optimized protection against deleterious influence of salinity.     

基于遗传算法的柴油机配气与供油正时参数优化

柴油机的配气与供油正时对其性能影响很大,最佳的匹配参数能够形成缸内良好的空燃比、较佳的燃烧效率以及较低的燃油消耗率。以单缸135型柴油机为研究对象,采用遗传算法对配气与供油正时参数进行优化,提高了柴油机的燃油经济性。     

城市道路混合交通流道路交叉口信号配时优化方法

机动车、行人以及非机动车往往是构成现代道路交叉口的主要元素。随着城市路网建设的不断扩大,交通秩序失衡及交通冲突等问题也随之增加。本文在对机动车、非机动车及行人流的自身特点进行分析的基础上,以排队车辆、延误为优化目标,提出混合交叉口交通信号配时优化方法,并基于实测数据运用交通流仿真软件对优化方案进行校验。结果表明,优化后的Webster信号配时方案可为混合交通信号交叉口设计提供基础理论支撑,为城市道路交通控制提供有效的控制方法支持。     

四种杀菌剂防治猕猴桃溃疡病的效果及田间应用技术

为探究猕猴桃溃疡病的化学防治技术,采用离体枝条室内生测及田间试验的方法,对72%农用链霉素SPX、46%氢氧化铜WG、20%叶枯唑WP及1.5%噻霉酮EW的预防和治疗效果以及施药的时期和方法进行了研究。结果显示,供试杀菌剂对猕猴桃溃疡病均有显著的预防效果和一定的治疗效果,在浓度为4.0 mg/m L和2.0 mg/m L时,对病害病斑15 d的预防效果分别达到100%和68.0%以上,较相同浓度的治疗效果高2~3倍,预防和治疗效果均达到90%时的杀菌剂浓度分别为3.07~3.35 mg/m L和8.32~10.81 mg/m L,药效持效期约为11~14 d。田间全树喷雾和树干涂药试验表明,农用链霉素和氢氧化铜预防效果较好,超过60%;秋冬季枝干发病前施药4~5次预防效果可达70%左右;枝干发病显症初期采用病斑划道后涂药治疗效果较好,但对大于15 cm的中大型病斑治疗效果较差,而枝干发病后采取药剂注射及药剂涂抹法治疗病斑效果均较差。表明秋冬季是预防猕猴桃溃疡病的关键期,而发病初期为治疗最佳时期。     

CLIMATE-CHANGE-INDUCED TEMPORAL VARIATION IN PRECIPITATION INCREASES NITROGEN LOSSES FROM INTENSIVE CROPPING SYSTEMS: ANALYSIS WITH A TOY MODEL

A simple ‘toy’ model of productivity and nitrogen and phosphorus cycling was used to evaluate how the increasing temporal variation in precipitation that is predicted(and observed) to occur as a consequence of greenhouse-gasinduced climate change will affect crop yields and losses of reactive N that can cause environmental damage and affect human health. The model predicted that as temporal variability in precipitation increased it progressively reduced yields and increased losses of reactive N ...     

基于区块链的农情数据可信融合共享模型设计与实现

为了提高现有农产品区块链溯源模型中的数据传输和查询效率，提出了基于区块链的农情数据可信融合共享模型。首先构建农情数据采集存储优化模型，通过Kafka节点接收网关数据并将结构化数据、非结构化数据哈希值存于区块链，非结构化数据存储于HDFS（Hadoop Distributed File System，Hadoop分布式文件系统），提升了数据传输效率。其次设计农情数据融合重组共享模型，利用Spark将结构化数据进行重组融合，将融合后的结构化数据、非结构化数据索引存储于Hbase，融合数据哈希值存储于区块链，提升了溯源效率。最后构建农情数据可信验证应用模型，通过比对Hbase中的融合数据哈希值与链上融合数据哈希值、HDFS中各环节非结构化数据哈希值与链上环节哈希值甄别数据真伪，保证了数据的真实性、可信性。在此基础上设计了基于区块链的农情数据可信融合共享系统，并在一玉米供应链进行了实际应用。进行相关测试后发现，与传统的单链型追溯模型相比，本模型全供应链数据存储时间缩短5.26 %，数据查询时间缩短43.47 %。应用结果表明，此模型可以在保证数据可信前提下，通过数据的融合共享提高数据传输效率与数据查询效率，可为农产品供应链溯源系统的研发提供参考。     

时序分析在排种轴转速检测数据处理中的应用

利用CCD摄像机获取气吹式精密排种器排种轴视觉检测样本,通过图像处理获得转速序列,在分析转速序列特点的基础上,采用时序分析方法研究排种轴转速。利用转速序列数据计算各种转速下的自协方差函数、自相关函数和偏自相关函数,选用AR模型进行转速序列的分析。将实测数据代入AR模型求得模型参数,应用模型进行转速序列数据拟合(以45 r/min为例),获得模型拟合值、残差序列。残差序列和模型拟合优度分析结果表明,模型预测的残差最大值为19.920 6,并且有83.83%的残差在允许值±6.912 312 r/min范围内;模型拟合度为74.631 2%,标准方差为0.050 136,模型系数t检验结果为16.805 28,显著性水平0.000通过t检验。