Ecological environment analysis of Abies holophylla plantations under different cutting systems

Different types of plantations were observed in Baishilazi National Nature Reserve, Liaoning Province, for 34 a. The environmental quality ofAbies holophylla plantations was analyzed under different cutting systems. Analysis factors included soil erosion rate, humification degree of litters, and water hold capacity. The surface soil loss of clear cutting area was 19000t·km?2·a?1 more than that of selective cutting area. The content of soil organic matter in board-leaved—Abies holophylla forest was 4.62% more than that in pure stand, and the water hold capacity of the mixed forest was 1.43 time of that of pure stand. The mixed forest of board-leaved—Abies holophylla by selective cutting can upgrade the ecological environment quality.

Research on the Mechanism of Abrasive Particles Accelerated and a Cutting System of a Premixed Abrasive Jet

Forces acting on abrasive in the process of speeding up have been analyzed. Motion differential equation of abrasive in a pipeline and nozzle has been given, respectively. Mechanisms of abrasive particles accelerated in a premixed abrasive jet has been analyzed. The study shows that driven by high-pressure water, velocity of an abrasive is near to velocity of water in pipeline through the acceleration distance. In the taper section of a nozzle, water and abrasive particles are greatly accelerated at the same time. But velocity of an abrasive always lags behind velocity of water. A premixed abrasive jet cutting system has been introduced. The structure and working principles of the system have been given. The system is an assembly of abrasive screening and filling. By use of the premixed abrasive jet cutting system established, cutting experiments have been made to test the main parameters which influence the cutting performances such as working pressure, standoff and traverse velocity, and the nozzle diameter affecting cutting chink width.

Temperature distribution in the tool-chip-workpiece system during the orthogonal cutting process

The temperature distribution in the tool, chip and workpiece was studied during the orthogonal cuttingprocess Under several different cutting conditions. The temperature distribution is calculated by the finite differencemethod. and the variation of the material properties with temperature was taken was taken into account The results obtained arecoincident with both previous published results and experimental measurements.

Effects of Lactoperoxidase System Activation-Oregano Essential Oilor Chlorine on the Quality of Modified Atmosphere Packaged Fresh-Cut Iceberg Lettuce

The present work focused on the effects of the Modified Atmosphere Packaging (MAP) 1 (5% O2 and 10% CO2) or 2 (2% O2 and 5% CO2) and the previous addition of Lactoperoxidase System (LPS) and Oregano essential oil or chlorine washing on the quality of fresh-cut lettuce during refrigerated storage at +4?C. Our results showed the significant effect of this combined treatment on quality improvement during storage. Thus, mesophilic bacteria was reduced in treated samples compared to those untreated with number which not exceeded the critical of 5 × 107 UFC?g-1 (p 2 and CO2 levels created by both atmosphere were not significantly different between the two treatments (p > 0.05). Brightness of lettuce samples was significantly reduced during storage. Thereafter, the PCA data showed the effect of combined treatment on the preservation of hygienic, physico-chemical and sensory quality up to the 7th day of refrigerated storage of these treated samples. The results obtained draw attention to modified atmosphere packaging lettuce and the addition of bio-preservatives which could be an alternative of choice to replace chlorine to preserve the sanitary quality of green products.

导光板中一种V-Cut槽结构的设计方法

提出了一种V-Cut槽结构的液晶导光板表面微结构设计方法,确定了V-Cut槽自身参数影响导光板性能的规律,通过大量的实验工作对不同的微结构设计方式进行了对比,确定了V-Cut槽的最佳排布方式即多项式排布方式。总结了多项式中各个参数所代表的含义,确定了V-Cut槽结构按照多项式方式进行设计的规律。经检验,此方法能够设计出光能利用率高、均匀性在80%以上的高性能导光板。

Investigation of rockfall-prone road cut slope near Lengpui Airport,Mizoram,India

Rockfall is one of severe natural hazards that are frequently reported in northeast region of India. It carries rock block falling from the cliff with high velocities and energies which can result in damages to vehicles, disruption to transportation, injuries and fatalities. The massive rockfall event which occurred in April 2017 on the highway NH-44 A, near Lengpui Airport, blocked the traffic for 1 d, and fortunately,no casualties were reported as the event occurred in the night. This is the only highway connecting the Aizawl city to the airport and the region is highly prone to rockfall events. Hence assessment of rockfall along this highway is necessary. In the current study, rockfall hazard assessment has been carried out on three locations by rockfall hazard rating system(RHRS). During pre-failure analysis, the result shows that most hazardous slopes have RHRS score of 639. The slopes were found to be vulnerable and later on the rockfall activity occurred. Three-dimensional(3 D) stability analysis has been carried out using 3 DEC software package to analyze the failure behavior and to decide the rockfall-prone zone(unstable blocks)for slope. The total displacement of 2.24 cm and velocity of 2,25 mm/s of the failed block have been observed in the numerical analysis. Further, the rockfall vulnerable zone(unstable blocks) is considered to determine the parameters such as run-out distance, bounce height and energies of the falling rock blocks. The maximum total kinetic energy of 5047 kJ has been observed in the numerical analysis with the maximum run-out distance up to 18 m.

基于SimPower System工具箱的带限流保护直流调速系统仿真

文章介绍了Matlab的电力系统(SimPower System)工具箱,以带限流保护的直流调速系统为例,叙述了仿真模型的搭建过程并进行仿真研究。结果表明,该仿真方法很好地解决了模型的精确与实现的矛盾,具有很高的可信度和真实性,有一定的工程实用价值。

云存储系统中文件分界点确定方法——Cut-GAR

针对Hadoop分布式文件系统(HDFS)中小文件定义模糊导致HDFS处理小文件性能不佳的问题,提出了一种云存储系统中文件分界点的确定方法——Cut-GAR。该方法分析消耗Name Node内存(M)、文件上传速度(MUFS)、文件读取速度(MAFS)与文件大小之间的关系,得出文件大小三个近似最优值,FM、FMUFS、FMAFS;然后利用灰度关联分析,将M、MUFS、MAFS作为评价指标,文件大小作为评价对象,得到评价指标-评价对象灰色关联度以及评价指标所占权重,将FM、FMUFS、FMAFS与对应权重相乘,得出文件分界点。实验结果表明,Cut-GAR在M、MUFS和MAFS三者之间取得平衡,可以有效确定文件分界点,提升小文件处理性能。

灌木平茬机切割系统参数优化设计与验证

为分析圆盘锯式切割系统的切割机理,在Solidworks中建立单组圆盘锯及灌木枝条的简化模型,并在动力学分析软件ABAQUS中进行仿真分析,研究灌木切割过程中工作参数与圆锯片参数的关系。同时,以锯片转速、行进速度、枝径为影响因素,以锯切力为评价指标,对其影响的因素进行虚拟正交试验,并用Design Expert动态响应软件进行分析,得到响应面回归方程,得知当圆锯转速为2500r/min、前进速度为0.9m/s时平茬效果较好。用小型灌木平茬机上进行实地试验,结果表明破茬率和留茬高度均能满足农艺要求。

Deep-Sea Cobalt Crusts Water Jet Cutting Ability

Deep-sea cobalt crusts water jet cutting method is proposed to avoid cutter impact load. With simulation calculations and experimental tests, water jet system parameters and its cutting ability were studied. Simula-tion results show that working pressure, ejection range and ejection angle of water jet system are main parameters of its cutting ability. Its important degree is in turn the working pressure, ejection range and ejection angle. Increasing water jet system working pressure is the most effective way to improve its cutting ability. When water jet working pressure is constant, in order to improve its cutting ability, the ejection range should be less than 4mm (four times of nozzle diameter) and the ejection angle should be about 13o. Experimental results show that there is a threshold pressure during water jet cutting cobalt crusts simulation material. With the increase of water jet working pressure, its cutting ability increases dramatically. With the increasing of water jet ejection range, its cutting ability decreases sharply. The optimal ejection angle is about 13o

高精度无心车床刀盘系统动态特性分析

无心车床是线性棒料表面处理的重要设备,刀盘系统是无心车床的重要部分,可以直接影响加工精度。这里以XF-WXC无心车床刀盘系统为研究对象,对刀盘系统进行模态分析,得到前六阶固有频率和模态振型,再通过设置不同工况转速,分析不同转速对刀盘系统模态频率的影响规律,并基于模态分析结果进行不同工况下的谐响应分析,研究刀盘系统的动态特性。分析结果表明:刀盘系统的刀尖位置为受力变形最大部位;易发生共振的激励频率在278Hz、449Hz和480Hz附近,在共振频率处的最大形变位移为0.036mm;同时利用实际切削实验结果验证仿真分析的可靠性。为无心车床的进一步优化设计提供理论依据。

难加工材料纵扭超声振动辅助铣削加工研究进展

纵扭复合超声振动辅助铣削(LTUVAM)是在刀具轴向与扭转方向上施加高频微幅振动的一种辅助铣削技术,具有降低切削力与切削热、提高工件表面质量、提高表面残余压应力、减少刀具磨损等诸多优点。本文围绕难加工材料的铣削加工进行了系统综述。在设备制造方面,阐述了纵扭复合超声振动系统的结构设计方法与工作原理;在工艺开发方面,从LTUVAM的切削刃运动轨迹及切削特性入手,分析各类材料的切削加工性能,并总结了LTUVAM的优势及应用。最后,本文对LTUVAM的未来发展趋势进行展望。

Sysmex UF5000尿沉渣分析仪建立RBC WBC CAST阳性cut off值及准确性评估

目的建立Sysmex UF5000尿沉渣分析仪检测尿液标本相关参数红细胞(RBC)、白细胞(WBC)、管型(CAST)的阳性cut off值,并评价其性能。方法选取1059例尿液标本在Sysmex UF5000尿沉渣分析仪上进行检测,并离心镜检。以镜检结果作为金标准,ROC曲线分析RBC、WBC、CAST的阳性cut off值,并计算其敏感性、特异性、符合率、假阳性率和假阴性率等。进一步分析假阳性标本的影响因素和部分假阴性标本。结果阳性cut off值:RBC>16/μL(男)或>15/μL(女);WBC>17/μL(男)或>30/μL(女);CAST>0.49/μL。相关的敏感性、特异性、符合率均较高。假阳性标本影响因素中RBC男性主要是结晶,女性以结晶、细菌为主;WBC女性以鳞状上皮细胞为主,男性未见明显的影响因素;CAST均以黏液丝和鳞状上皮细胞为主。假阴性率低于5%,其中仅有9例为肾脏、泌尿系统疾病标本,占比0.85%。结论本实验室设置的UF5000尿沉渣分析仪RBC、WBC、BACT阳性cut off值,相关的敏感性、特异性、假阴性率和符合率均符合ISO15189认可和实验室的日常工作需求。

The Use of Genetic Approach to the Kinematics of Cutting

This article deals with the use of an interdisciplinary approach to modelling and creation of a complex technical system of different physical nature in relation to the kinematics of cutting and shaping. The professor of the National Technical University of Ukraine, Kuznetcov Iu. N., proposed the approach based on generalization of knowledge, methodological basis of which is the theory of evolution of the systems and methods of genetic analysis and synthesis. For generalization of the knowledge in the fundamental sciences is based on the principles of a limited number of elementary generic structures with the introduction of the gene concept. The modelling and synthesis of kinematic cutting schemes are providing the efficiency and viability of genetic and morphological approach. The material point, which can interact with other ma-terial points in space and time, simulating anthropogenic system of different origin, is introduced as a material object.

干旱胁迫对彩菊切花幼苗根系构型和生理活性的影响

以6个品种彩菊切花幼苗为试材,通过盆栽和人工浇灌20 mmol·L^(-1)浓度PEG 6000模拟干旱胁迫处理,探究彩菊切花在干旱胁迫第5、10、15、20天时根系构型和生理指标变化,选出抗旱性强、适应宁夏地区大面积推广与种植的优良彩菊切花品种,以期为西部干旱地区菊花品种的推广提供参考依据。结果表明:随着干旱胁迫的持续,彩菊切花的根系总长度、根系总表面积、根系总体积与总根系指标的关联程度较大。除根系总体积外,根系平均直径与其他根系指标不存在相关性。与正常浇水相比,不同品种彩菊切花的叶片相对含水量和叶绿素含量不断下降,相对电导率和可溶性蛋白质含量升高,丙二醛和可溶性糖含量先上升后下降,过氧化物酶活性呈先下降后上升趋势,超氧化物歧化酶活性呈先上升再下降最后上升的趋势。

Improving Rule Base Quality to Enhance Production Systems Performance

Production systems have a special value since they are used in state-space searching algorithms and expert systems in addition to their use as a model for problem solving in artificial intelligence. Therefore, it is of high importance to consider different techniques to improve their performance. In this research, rule base is the component of the production system that we aim to focus on. This work therefore seeks to investigate this component and its relationship with other components and demonstrate how the improvement of its quality has a great impact on the performance of the production system as a whole. In this paper, the improvement of rule base quality is accomplished in two steps. The first step involves re-writing the rules having conjunctions of literals and producing a new set of equivalent rules in which long inference chains can be obtained easily. The second step involves augmenting the rule base with inference short-cut rules devised from the long inference chains. These inference short-cut rules have a great impact on the performance of the production system. Finally, simulations are performed on randomly generated rule bases with different sizes and goals to be proved. The simulations demonstrate that the suggested enhancements are very beneficial in improving the performance of production systems.

基于RBF神经网络的汽车内饰皮革智能切割系统设计

随着汽车用皮革的迅速发展,开发一套满足汽车内饰皮革生产需求的智能切割系统具有重要意义。本文简述了汽车内饰皮革切割系统的发展,构建了基于径向基函数(Radial Basis Function,RBF)神经网络的汽车内饰皮革智能切割系统,介绍了系统主要硬件配置选型和软件的设计,提出了基于RBF神经网络PID(Proportional Integral Derivative,比例-积分-微分)控制算法;通过搭建试验平台,测试汽车内饰皮革智能切割系统的可行性、切割精度与效率。结果表明,该系统能够较好地满足汽车内饰皮革切割方面的需求。

Minimal cut-based recursive decomposition algorithm for seismic reliability evaluation of lifeline networks

In this paper, a new probabilistic analytical approach, the minimal cut-based recursive decomposition algorithm （MCRDA）, is presented to evaluate the seismic reliability of large-scale lifeline systems. Based on the minimal cut searching algorithm, the approach calculates the disjoint minimal cuts one by one using the basic procedure of the recursive decomposition method. At the same time, the process obtains the disjoint minimal paths of the system. In order to improve the computation efficiency, probabilistic inequality is used to calculate a solution that satisfies the prescribed error bound. A series of case studies show that MCRDA converges rapidly when the edges of the systems have low reliabilities. Therefore, the approach can be used to evaluate large-scale lifeline systems subjected to strong seismic wave excitation.

适用于嵌入式系统的车道线检测算法

提出使用基于车道线的ROI切割方法,合理去除图像无用部分,有效减少图像处理面积,为后续图像处理减轻计算量。为了提高算法效率,对图像进行了阈值分割,利用Hough变换进行车道线检测,提取图像有效信息。为了准确划分出ROI区域,采用基于车道线的ROI划分方法,适用性强,可靠性高,为系统之后的处理减小图像面积,有利于提高系统的实时性。通过对实际道路图像的实验,显示出该方法在运行时间和检测正确率方面明显优于传统滤波方法,尤其适用于嵌入式系统。

包覆面料裁片切割机横梁进给系统建模及动态特性分析

包覆面料裁片切割机是用于制作软体家具的主要设备之一,其横梁进给系统存在复杂的机电耦合作用。为在设计阶段研究其横梁进给系统切割定位工况下的动态特性,优化横梁进给伺服驱动控制系统参数,建立了横梁进给系统的机电-刚柔混合模型。拟定横梁进给系统的响应效率、定位精度和刀尖运动稳定性作为动态特性评价指标,探究了横梁进给伺服驱动控制系统参数对横梁进给系统动态特性的影响。结果表明:建立的横梁进给系统机电-刚柔混合模型,为横梁进给系统动态特性分析奠定了基础。增大位置环比例系数可提高横梁进给系统的响应效率和定位精度,增大速度环比例系数可有效提高横梁进给系统的刀尖运动稳定性。研究结果可为提高软体家具生产效率和制造质量提供技术保障。