Flexible Fixture Design for the Top and End Surface Processing of NP2_NP4 Cylinder Heads

This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and working procedure which formed the basis for the design of the processing technology scheme,a selection of suitable machine tools,and the setting of processing parameters.Fixtures tailored to the chosen machine tools were then designed to meet the processing requirements.Additional aspects of the project included the design of part drawings,calculation of working time quota,design of auxiliary guides,support clamping,and hydraulic circuits,all aimed at fulfilling practical production requirements.

FE simulation and process analysis on forming of aluminum alloy multi-layer cylinder parts with flow control forming

The aluminum alloy parts used in airbag of car were studied with flow control forming(FCF) method, which was a good way to low forming force and better mechanical properties. The key technology of FCF was the design of control chamber to divide metal flow. So, the design method of FCF was analyzed and two type of control chamber were put forward. According to divisional principle, calculation model of forming force and approximate formula were given. Then forming process of aluminum alloy multi-layer cylinder parts was simulated. The effect of friction factor, die radius and punch velocity on metal flow and forming force was obtained. Finally, the experiment was preformed under the direction of theory and finite element(FE) simulation results. And the qualified parts were manufactured. The simulation data and experimental results show that the forming sequence of inner wall and outer wall, and then the force step, can be controlled by adjusting the process parameters. And the FCF technology proposed has very important application value in precision forging.

A preliminary analysis of physical mechanism of transformation process from a landed typhoon into an extratropical cyclone

A diagnostic study is performed in the paper on the process of typhoon Norris (1980) transforming into an ex-tratropical cyclone after its landing over Southeast China. The main findings are as follows:The changes of kinetic energy are mainly attributed to the generation due to non-divergent wind. During the early stage of the typhoon landing, there exits only a small quantity of kinetic energy exchanging with the environment. And after it is transformed into an extratropical cyclone, a large amount of kinetic energy is exported from the system toward the environment.The horizontal and vertical flux-divergence terms of eddy available potenlial energy are the prominent sinks in the budgets of eddy kinetic energy. The generations of eddy kinetic energy due to both the barotropic and baroclinic processes are source terms. The former is remarkable during the initial stage. But after the depression is transformed into an extratropical cyclone, the roles of the generation by the barotropic and baroclinic processes are reversed, 1. e. , the latter has become more significant than the former.Diabatic heating is the most dominant heat source. The terms of vertical heat flux by cumulus and large-scale motion are the major sinks. And the latter is prominent after the system is transformed into an extratropical cycfone.

Integrated use of GIS, remote sensing and multi-criteria decision analysis to assess ecological land suitability in multi-functional forestry

The Zagros forests are a treasure of valuable oak forests, but they have been severely degraded from long-term misuse. Geographic information systems （GIS） and multi-criteria decision analysis （MCDA） have been increasingly used to improve the management of vulnerable ecosystems to prevent further degradation and increase the sustainability of land use. This study presents a methodology to assess land suitability using remote sensing （RS） to obtain wall-to-wall data for the calculations, GIS to analyze the data, and MCDA to rank alternative land uses. The criteria and subcriteria affecting the suitability of land for different uses were identified and weighted using an analytic hierarchy process. Variables used as subcriteria were assessed using satellite data and other sources of information such as existing maps and field surveys. Numerical values for the subcriteria were classified, and each class was given a priority rating according to expert judgments. Based on the ratings and weights of the subcriteria, a priority map was created for each land use using the weighted linear combination method. The priority maps for different land uses were overlaid to obtain a preliminary land use map, which often indicated several simultaneous land uses for the same location. The preliminary map was further edited by removing unrealistic, mutually exclusive land-use combinations. The study tested and demonstrated the potential of integrating RS, G1S and MCDA techniques for solving complicated land allocation problems in forested regions using a scientifically sound and practical approach for efficient and sustainable allocation of forestland for different uses.

Safety analysis of wheel brake system based on STAMP/STPA and Monte Carlo simulation

The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.

Potential Analysis of Inefficient Garden Land and Residual Forest Land Remediation in Comprehensive Land Remediation of the Whole Region—A Case Study of Zhemu Town, Guilin City, China

The remediation of inefficient garden land and defective forest land is one of the important sources and types of supplementary cultivated land in the comprehensive land remediation of the whole region. The remediation and development of inefficient garden land and defective forest land will effectively alleviate the multiple pressures faced by cultivated land at present. Taking Zhemu Town, Guilin City, China as an example, on that basis of the data of the third national land survey, using analytic hierarchy process, this paper selects six evaluation factors, including water source, traffic, slope, field concentration, farmland infrastructure and villagers’ will, to study the remediation potential of inefficient garden land and defective forest land in Zhemu Town, and delimits four potential divisions, in order to provide the basis for the arrangement of land remediation projects in Zhemu Town. The results show that the northern, central and western regions of Zhemu Town have great remediation potential.

Aspect-Based Sentiment Analysis for Polarity Estimation of Customer Reviews on Twitter

Most consumers read online reviews written by different users before making purchase decisions,where each opinion expresses some sentiment.Therefore,sentiment analysis is currently a hot topic of research.In particular,aspect-based sentiment analysis concerns the exploration of emotions,opinions and facts that are expressed by people,usually in the form of polarity.It is crucial to consider polarity calculations and not simply categorize reviews as positive,negative,or neutral.Currently,the available lexicon-based method accuracy is affected by limited coverage.Several of the available polarity estimation techniques are too general and may not reect the aspect/topic in question if reviews contain a wide range of information about different topics.This paper presents a model for the polarity estimation of customer reviews using aspect-based sentiment analysis(ABSA-PER).ABSA-PER has three major phases:data preprocessing,aspect co-occurrence calculation(CAC)and polarity estimation.A multi-domain sentiment dataset,Twitter dataset,and trust pilot forum dataset(developed by us by dened judgement rules)are used to verify ABSA-PER.Experimental outcomes show that ABSA-PER achieves better accuracy,i.e.,85.7%accuracy for aspect extraction and 86.5%accuracy in terms of polarity estimation,than that of the baseline methods.

Plant drought tolerance trait is the key parameter in improving the modeling of terrestrial transpiration in arid and semi-arid regions

陆面过程蒸腾作用的模拟制约着天气,气候降水预测的精确度.近几十年来,为了更好地描述植被蒸腾的水力约束,陆面过程模式发展了基于植物性状的植物水力胁迫方案.然而,我们对于植物性状在蒸腾模拟中的地位仍然缺乏了解,植物性状对蒸腾的重要性仍需进一步量化.本研究利用Morris方法评估植物性状参数在通用陆面模式植物水力胁迫方案(CoLM-P_(50)HS)中的重要性,针对17种植物性状,筛选出最为重要的:耐旱性状(P_(50)),气孔性状,和光合作用性状.在12个FLUXNET站点中,参数的重要性由归一化敏感度来衡量.P_(50)的重要性随着降水的减少而增加,而气孔性状和光合作用性状的重要性则随着降水的减少而减少.在干旱或半干旱地区,P_(50)比气孔性状和光合作用性状更重要,这意味着当植物经常经历干旱时,水力安全策略比植物生长策略更关键.而耐旱性状的巨大变异性进一步暗示了多种植物水力安全策略的共存.忽视P_(50)的变异性可能会对陆面过程模式蒸腾作用的模拟造成严重误差.因此,为了更好地表示植物水力功能的变异性,需要增加对耐旱性状的观测并耦合到陆面模式中.

我国饲料粮供给区域差异时空演化特征及影响因素分析

文章旨在探究我国饲料粮供给区域差异时空演化特征及其影响因素。选取2005—2021年我国31个省份的月度面板数据,使用空间自相关和冷热点分析法深入探究饲料粮供给区域差异时空演化特征,进一步通过泰尔指数与空间杜宾模型深入剖析其驱动因素。结果显示,饲料粮供给冷点与热点区域均呈现集中态势,且其局部空间关联性较为明显。饲料粮供给空间分布格局检验结果表明,北部沿海地区多为“低-低”型区域聚集区,东北、东南沿海与西南地区多为“高-高”型区域聚集区。泰尔指数与结构性原因分析显示,饲料粮供给水平呈现明显正向空间溢出效应,其中组内差异是区际差异的关键因素。空间杜宾模型结果表明,土地生产率、交通运输水平、粮食生产机械投入和饲料粮加工水平是饲料粮供给水平的重要影响因素。

结合STPA和DEMATEL-ISM的民机起落架收放系统风险研究

为从系统整体角度完成对起落架收放系统的风险辨识和影响分析,将系统理论过程分析(Systematic Theory Process Analysis,STPA)与决策实验室分析-解释结构模型(Decision Making Trial and Evaluation Laboratory Interpretive Structural Modeling,DEMATEL-ISM)相结合来开展分析。首先,定义事故和系统级危险,以民机进近阶段放下起落架为例,运用STPA完成对风险因素的系统化辨识;其次,基于最大平均熵减(Maximum Mean De-entropy,MMDE)算法帮助DEMATEL-ISM模型确定阈值,完成对风险因素影响的重要性分析并识别可能引发系统级危险的风险传递路径,据此挖掘关键致因场景,以给出风险预防建议。结果显示:线路性能退化或失效、位置作动控制组件(Position Action Control Unit,PACU)核心处理器故障为关键原因因素,收放作动筒作动异常、机组成员操作不当、起落架指示灯显示异常、起落架液压选择阀作动异常、PACU信息接收有误为关键结果因素,这些因素均涉及多条可能引发系统级危险的风险传递路径,应予以重点控制。

基于Landsat TM与CBER-02B的土地覆盖变化分析

以Landsat TM和CBERS-02B图像为遥感数据源,运用RS与GIS技术,对遥感数据的处理方法和技术流程进行系统的研究,并对汉寿县三期遥感影像进行处理,增强影像的可识别性。在野外调查和室内判别的基础上,建立研究区解译标志,采用机助目视解译方法,建立了1994年、2003年及2008年汉寿县土地覆盖数据库,提取并分析汉寿县土地覆盖变化信息。

煤油末段密闭加注管路抽泄流程优化分析

为了解决煤油末段密闭加注管路抽泄流程可能出现的加注精度及煤油品质的问题,通过分析管路内煤油变化的影响因素,讨论了压力和温度的变化引起的管路形变,构建了温度、管径、形变压力的热力学计算模型,试验验证了模型计算的准确性,根据模型数值计算结果,提出了抽泄流程优化措施,确保了加注管路抽泄流程的可靠性。

钢结构厂房吊装作业钢丝绳选型分析

起重机械是施工作业不可缺少的设备,施工作业过程中存在大量频繁的吊装作业,吊装作业管控是预防起重机械事故多发高发的关键环节。为了保证吊装作业的安全性,吊装作业前必须根据钢丝绳所受的拉力大小,正确选用合适的吊装用钢丝绳。本文主要对钢结构厂房吊装钢梁柱过程中吊装用钢丝绳进行安全受力验算,计算出钢丝绳所受拉力大小,从而快速正确的选取符合吊装需求的钢丝绳规格。

基于PLM+AHP的海南省耕地占补平衡实施效果评价

为落实好海南省耕地占补平衡工作,首先基于项目逻辑模型构建海南省耕地占补平衡实施效果评价指标体系,然后基于层次分析法,计算各层指标的权重值,对海南省2017~2022年耕地占补平衡实施效果进行评价分析。结果表明:投入、活动、产出、效果、影响的平均得分分别为6.7、5.6、4.3、6.0、5.5分,2017~2022年占补平衡实施效果评价得分整体上呈先增大后减小的变化特征,具体排序为2019年>2020年>2022年>2017年>2021年>2018年;文昌市和陵水县分别是海南省耕地占补平衡实施效果最好和最差的地区。根据2017~2022年海南省耕地占补平衡实施评价结果,文章有针对性地提出了耕地占补平衡政策绩效改进工作的建议,旨在为海南省今后耕地占补平衡政策的制定和实施提供参考。

Numerical Forecasting of Icing on Structural Components of Offshore Platforms in Polar Regions

The Polar Regions are rich in natural resources but experience an extremely cold climate.The surfaces of offshore platforms operating in the Polar Regions are prone to icing.To develop solutions to this problem of surface icing,the influence of both the liquid water concentration of the surrounding atmosphere and the average water droplet diameter on the formation of ice on two major structural components of offshore platforms was analyzed using a combination of Fluent and FENSAP-ICE.Results showed that at a wind speed of 7 m/s,as the concentration of liquid water in the air increases from 0.05 to 0.25 g/m3,the amount and thickness of the icing on the surfaces of the two structural components increase linearly.At a wind speed of 7 m/s and when the size of the average water droplet diameter is 20–30(30–35)μm,as the average water droplet diameter increases,the amount and thickness of the icing on the surfaces of the two structural components increase(decrease)gradually.

Landform Instability and Land-use Dynamics in Tropical High Mountains, Central Mexico

This investigation is an analysis of the influence of landform instability on the distribution of land-use dynamics in a hydrographical basin, located in the Mexican Volcanic Belt mountain range (central Mexico), currently affected by substantial changes in land use and deforestation. A landform map was produced, in addition to seven attribute maps - altimetry, drainage density, slope, relief energy, potential erosion, geology and tectonics - which were considered as factors for determining landform instability through Multi-criteria Evaluation Analysis. Likewise, the direction and rhythm of land-use dynamics were analyzed in four dates - between 1976 and 2000 - and cross tabulations were made between them, in order to analyze the trends and processes of land-use dynamics. Afterwards, the databases obtained were cross tabulated with the landform variables to derive areas, percentages and correlation indices. In the study area, high-instability landforms are associated with most ancient volcanic and sedimentary landforms, where high altitude, drainage density, slope and potential to develop gravitational and fluvial processes are the major factors favouring a land-use pattern, dominated by the conservation of extensive forest land, abandonment of human land use and regeneration of disturbed areas. In contrast, low-instability landforms correspond to alluvial plains and lava hills covered by pyroclasts, where low potential erosion to develop fluvial processes, added to water and soil availability and accessibility, have favoured a land-use pattern dominated by the expansion of agroforestry plantations and human settlements, showing a marked trend towards either intensification or permanence of the current land use and with little abandonment and regeneration.

Approach to Power Spectrum Density Values in Three Dimensional Acceleration of Ground Motions

In this paper, based on the random characteristic analysis of Tianjin Hospital earthquake waves of Tangshan aftershock, the three dimensional acceleration power spectrum density ratio has been presented.

Geomorphologic map of the 1st Mutnaya River,Southeastern Kamchatka,Russia

The Kamchatka Peninsula – situated in the Pacific "Ring of Fire" – has 29 active and over 400 extinct volcanoes. Since it is situated in the northeastern extremity of Russia, in subarctic climate,the volcanic landforms are overprinted by the 446 glaciers. This research focuses on the 1^(st) Mutnaya catchment which drains the southern slopes of two active volcanoes: Avachinsky and Koryaksky. Those volcanoes are a permanent threat for the cities of Petropavlovsk and Elizovo, which are the 2 of 3 cities of the peninsula. Hence, most of the studies carried out in the area dealt with the natural hazards and only few focus on landscape evolution. Thus, the purpose of this study was to elaborate a cartographic approach which integrates classic geomorphology with state of the art GIS and remote sensing techniques. As result,different landforms and related processes have been analysed and included in the first general geomorphologic map of the 1^(st) Mutnaya catchment.

Expert Systems Modeling for Assessing Climate Change Impacts and Adaptation in Agricultural Systems at Regional Level

Australian agriculture is very susceptible to the adverse impacts of climate change, with major shifts in temperature and rainfall projected. In this context, this paper describes a research methodology for assessing potential climate change impacts on, and formulating adaptation options for, agriculture at regional level. The methodology was developed and applied in the analysis of climate change impacts on key horticultural commodities—pome fruits (apples and pears), stone fruits (peaches and nectarines) and wine grapes—in the Goulburn Broken catchment management region, State of Victoria, Australia. Core components of the methodology are mathematical models that enable to spatially represent the degree of biophysical land suitability for the growth of agricultural commodities in the region of interest given current and future climatic conditions. The methodology provides a sound analytic approach to 1) recognise regions under threat of declines in agricultural production due to unfolding climatic changes;2) identify alternative agricultural systems better adapted to likely future climatic conditions and 3) investigate incremental and transformational adaptation actions to improve the problem situations that are being created by climate change.