基于形状变化的冗余机械手可操作性分析

受冗余机械手的可操作性理论和可操作性椭圆的启发,提出形状变化可操作性理论和形状变化可操作性椭圆。可操作性表示了冗余机械手在形状给定的前提下,它的每一个关节产生速度的性能;形状变化可操作性表示了当冗余机械手的手臂末端被给定任务时,其余中间关节产生速度的性能,即是形状变化性能,手臂末端执行给定的任务,如轨道追踪,因此不具备形状变化可操作性。对可操作性椭圆和形状变化可操作性椭圆进行比较和分析。通过对七关节机械手在二维平面内的轨道追踪和障碍物回避的实例分析、以及对三维空间内的不同姿势(即不同形状)下的七关节机械手所对应的不同形状变化可操作性椭圆的比较分析,能够认识到形状变化可操作性理论的提出对于评估和设计冗余机械手的结构和形状有着重要的实际意义。

原料变化对裂解装置操作的影响及应对措施

独山子百万吨乙烯装置在实际生产中裂解原料趋于多样性,杂质复杂,原料切换频繁,装置通过原料对比分析,为高双烯收率,提出一系列操作变化以及技术改造适应不同原料的加工,使其达到最大效益。

基于自编码器的带隐变迁的迹变化挖掘

针对带有隐变迁的部分迹变化无法利用活动间的行为轮廓关系检测的问题,引入了一种基于自编码器的迹变化挖掘方法。业务系统参考模型未知,对原始日志中的迹执行变化操作时,添加隐变迁等操作会导致活动间的行为轮廓关系未改变、而实际迹执行存在变化。利用自编码器学习原始日志的分布特征,挖掘实际日志中的每条迹是否发生删除、插入和移动变化操作,从迹的角度出发实现活动变化挖掘。通过Pytorch仿真实验,本所提方法可以检测出实际日志中执行变化操作的迹,实验结果表明自编码器在迹变化挖掘中有效。

时空XML文档中不一致性修正方法的研究

作为时空数据库的核心和基础,许多时空数据模型被提出以适应越来越多的应用.基于XML对时空数据建模的研究特别是修正时空数据在XML文档中的不一致性的研究还很少.首先,提出了一个基于XML的时空数据模型,并在此模型的基础上给出了时空数据在XML文档中的一致性条件.然后,对三种主要的变化操作即更新操作、插入操作和删除操作中的不一致性阐述了修正方法,并给出了相应的例子说明.最后,对这三种操作不一致性种类进行了讨论.

冗余机械手的形状变化可操作性理论分析及其井下应用

受可操作性理论和可操作性椭圆的启发,提出了形状变化可操作性理论和形状变化可操作性椭圆。形状变化可操作性表示了当冗余机械手的手臂末端被给定任务时,其余中间关节的形状变化性能。并对可操作性椭圆和形状变化可操作性椭圆进行了比较和分析,形状变化可操作性理论的提出对于井下作业有着重要的实际意义。

时态RDF数据的不一致性修复和预处理

资源描述框架(RDF)是由W3C提出的开放型数据模型,对语义Web中信息资源的语义表达和描述标准化。语义网的快速发展和RDF的普遍应用,产生大量的时态RDF数据。时态RDF数据的一致性能提高时态RDF数据的准确性,也有助于提高数据库系统的可靠性和高效性,对于时态信息处理也能提供可靠的保证。针对支持有效时间的时态RDF数据存在的不一致性情况,提出了相关的修复算法,对于时态RDF数据实时更新,分析变化操作产生的不一致性并进行了预处理,实验验证了可行性。

乙烯装置原料轻质化的综合评述

阐述了中国石油独山子石化1号乙烯装置,在实现加工原料轻质化过程中所面临的经济指标下降和实际操作不稳定等问题。针对上述问题详细分析了加工原料性能和裂解炉改造情况,以及论述了加工轻质化原料对装置的产品收率、加工损失率、燃动能耗和实际操作等方面的影响,并针对上述问题制定了改进措施和采取了跨区域系统解决方式,保证了在与设计工况偏离较大状况下,装置的平稳运行和效益的最大化。

Flow shop rescheduling problem under rush orders

In the environment of customization, disturbances such as rush orders and material shortages often occur in the manufacturing system, so rescheduling is necessary for the manufacturing system. The rescheduling methodology should be able to dispose of the disturbance efficiently so as to keep production going smoothly. This aims researching flow shop rescheduling problem (FSRP) necessitated by rush orders. Disjunctive graph is employed to demonstrate the FSRP. For a flow shop processing n jobs, after the original schedule has been made, and z out of n jobs have been processed in the flow shop, x rush orders come, so the original n jobs together with x rush orders should be rescheduled immediately so that the rush orders would be processed in the shortest time and the original jobs could be processed subject to some optimized criteria. The weighted mean flow time of both original jobs and rush orders is used as objective function. The weight for rush orders is much bigger than that of the original jobs, so the rush orders should be processed early in the new schedule. The ant colony optimization (ACO) algorithm used to solve the rescheduling problem has a weakness in that the search may fall into a local optimum. Mutation operation is employed to enhance the ACO performance. Numerical experiments demonstrated that the proposed algorithm has high computation repeatability and efficiency.

Optimum Operating and Regeneration Parameters of ZnI2 Catalyst for Converting Methanol to Triptane:An Ideal Component of Unleaded Aviation Gasoline

Conversion of methanol(MeOH) to 2,2,3-trimethylbutane(triptane) over zinc iodide(ZnI_2)catalyst was investigated in a closed batch reactor.Optimum operating parameters were searched and catalyst deactivation and regeneration behaviors were discussed.The fresh,spent and regenerated catalysts were characterized by XRD,TG and XRF measurements to elucidate the related mechanism.The experimental results showed that the triptane yield reached up to 12.2% under the process conditions,including a reaction temperature of 200℃,an initial pressure of 0.35 MPa,a reaction time of 2 h,and a Me OH to ZnI_2 molar ratio of 2.The catalyst was gradually deactivated after several run cycles.A small amount of iodine was lost and a certain amount of ZnO was formed on the deactivated ZnI_2 catalyst.Deactivation of the catalyst could be attributed to the reduction of ZnI_2 amount,resulted from iodine loss and formation of Zn O.It was firstly pointed out from our work that the deactivated catalyst could be well regenerated by the hydrogen iodide(HI) and the tert-butanol compensation method,wherein the latter was added as an initiator into the reaction system.The activity recovery of the deactivated(spent) catalyst might be related to the reformation of ZnI_2 and acceleration of the initiation step of this reaction.

Specific energy optimization in sawing of rocks using Taguchi approach

This work aims at selecting optimal operating variables to obtain the minimum specific energy(SE) in sawing of rocks.A particular granite was sampled and sawn by a fully automated circular diamond sawblades.The peripheral speed,the traverse speed,the cut depth and the flow rate of cooling fluid were selected as the operating variables.Taguchi approach was adopted as a statistical design of experimental technique for optimization studies.The results were evaluated based on the analysis of variance and signal-to-noise ratio(S/N ratio).Statistically significant operating variables and their percentage contribution to the process were also determined.Additionally,a statistical model was developed to demonstrate the relationship between SE and operating variables using regression analysis and the model was then verified.It was found that the optimal combination of operating variables for minimum SE is the peripheral speed of 25 m/s,the traverse speed of 70 cm/min,the cut depth of 2 cm and the flow rate of cooling fluid of 100 mL/s.The cut depth and traverse speed were statistically determined as the significant operating variables affecting the SE,respectively.Furthermore,the regression model results reveal that the predictive model has a high applicability for practical applications.

Identification of LPV Models with Non-uniformly Spaced Operating Points by Using Asymmetric Gaussian Weights

In this paper, asymmetric Gaussian weighting functions are introduced for the identification of linear parameter varying systems by utilizing an input-output multi-model structure. It is not required to select operating points with uniform spacing and more flexibility is achieved. To verify the effectiveness of the proposed approach, several weighting functions, including linear, Gaussian and asymmetric Gaussian weighting functions, are evaluated and compared. It is demonstrated through simulations with a continuous stirred tank reactor model that the oroposed aonroach nrovides more satisfactory aonroximation.

Modeling of a Reverse Flow Reactor for Methanol Synthesis Modeling of a Reverse Flow Reactor for Methanol Synthesis

An accurate one-dimensional, heterogeneous model taking account of axial dispersion and heat transfer to the reactor wall, and heat conduction through the reactor wall for methanol synthesis in a bench scale reactor under periodic reversal of flow direction is presented. Adjustable parameters in this model are the effectiveness factors for each of the three reactions occurring in the synthesis and a factor for the bed to wall heat transfer coefficient correlation. Experimental data were used to evaluate these parameters and reasonable values of these parameters were obtained. The model was found to closely predict the reactor performance under a wide range of operating conditions, such as carbon oxide concentrations, volumetric flow rate, and cyclic period.

The Features and Patterns of Revision Process in English Learners＇ Writing

Revision is an important part of writing process but it often baffles the researchers due to the difficulties in recording the revision process of students. Based on a self-made questionnaire and the online record of the revision process, this study describes the English learners＇ revision behaviors and process in their second semester of a two-year writing course. The analysis indicates that the English learners hold a positive attitude towards revision and but passive in resorting to outside sources for help. The source of the feedback has a great influence on their motivation of revision. On the other hand, although they use all types of revision operations, they concentrate on surface changes and simple operations.

Effect of Operation Variables on Hydrodenitrogenation and Hydrodesulfurization over NiMo/Al_2O_3 Catalysts

Using the JQ-II high pressure hydrogenation micro-reactor unit, the reactivity of Athabasca bitumen derived heavy gas oil was studied over commercial and homemade hydrotreating catalysts. The effects of catalyst preparation variables and the influences of operation conditions, such as pressure, temperature, hydrogen/oil ratio and space velocity were also examined. It was shown that the optimal concentrations of the active components were 5% of NiO, 20% of MoO3 and 3.5% of phosphorus (by mass), and the suitable operation conditions were determined experimentally.

Assessment of the Influence of Torrefied Biomass Physical Characteristics, Design and Operating Variables on Gasification Efficiency

Gasification efficiency is an important factor that determines the actual technical operation as well as the economic viability of using a gasifier system for energy production. In this study, the impact of the physical properties of torrefied bagasse and the influence of gasifier design and operating variables were investigated in a computer simulated downdraft gasification system. Results obtained from the study indicated an interrelationship between feedstock characteristics, especially with regard to feed size, design variables such as throat angle and throat diameter as well as gasifier operating conditions such as temperature of input air and feed input. These variables influenced the efficiency of the gasification process of sugarcane bagasse because of increased enhancement of combustion zone reactions, which liberated huge amount of heat that led to a rise in the temperature of the gasification process. This condition also created increased tar cracking within the gasification system, contributing to reduction in the overall yield of tar.

EU and international policies for hydrometeorological risks:Operational aspects and link to climate action

Changes in hydrometeorological characteristics and risks have been observed and are projected to increase under climate change. These considerations are scientifically well studied and led to the development of a complex policy framework for adaptation and mitigation for hydrometeorological risks. Awareness for policy actions is growing worldwide but no legal framework is in place to tackle climate change impacts on water at a global scale. With the example of international frameworks and the legislation on EU-level, this article elaborates that hydrometeorological risks are not considered in the framework of one single policy. However, various policy instruments are directly or indirectly considering these risks at different operational levels. It is discussed that a tailor-made framework for hydrometeorological risks would improve coordination at international or national level. A major drawback for a single operational framework is that hydrometeorological risks are scientifically tackled in two large communities: the disaster risk reduction community and the climate change adaptation community, both of which are bound to different research and operational funding budgets. In future, disaster risk reduction and climate change adaptation will need been seen as a complementary set of actions that requires collaboration.

Formation of crystalline particles from phase change emulsion： Influence of different parameters

Solidification or crystallization of phase change emulsion in the form of fine emulsion drops in a direct contact coolant at temperatures below their freezing point was studied. This work is mainly focused on the size and shape of the generated partides from phase change emulsified fats. Size of the particles is the major or key factor being considered during their formation, however, other factors that govern the particle size and shape were also observed. The operating parameters of the process were optimized in order to obtain particles of smaller size ranges in the window of current operating conditions. The crystallization of complex emulsion maffices is very difficult to control in the bulk at desired requirement. Hence, the emulsion drop to particle formation has advan- tage in comparison with the bulk solidification or crystallization. The main objective of this work is to achieve spherical emulsion particles in a direct contact cooling system. Parameters like： stat）ility, characterization, viscos- ity, and the effect of different energy inputs were examined. Moreover, the effects of the capillary size, interracial tension, temperature of the emulsion on the particle size were also monitrored.

The Policy Evolution From Social Governance To the Holistic Pension Service

Amid the complex domestic and international environment, Chinese management of the country transits from control gradually to the governance, national governance modernization pattern have also entered the stage of implementation strategy. The fifth Plenary Session of the 18th CPC Central Committee put forward the implementation strategy of the refinement of social governance, making the policy more operable in the implementation level. This paper mainly analyzes the policy evolution fTom the social governance to the holistic service of the aged.

Impact of 1.5°C and 2.0°C global warming on aircraft takeoff performance in China

Associated with global warming, climate extremes such as extreme temperature will significantly increase. Understanding how climate change will impact the airflights is important to the planning of future flight operations. In this study, the impacts of 1.5 and 2 degree's global warming on the aircraft takeoff performance in China are investigated using a unique climate projection data from an international collaboration project named HAPPI. It is found that the mean summer daily maximum temperature, which is a major factor that affects the flight through changing the aircraft's takeoff weight, will increase significantly with magnitude less than 1.5℃ over most parts of China except for the Tibetan Plateau. The half a degree additional global warming will lead to higher extreme temperature in the arid and semi-arid western China, the Tibetan Plateau and the northeastern China, while the change in eastern China is weak. Five airports including Beijing, Shanghai, Kunming, Lasa and Urumqi will see ～1.0°-2.0℃(1.4°-3.0℃) higher daily maximum temperature under 1.5℃(2.0℃) scenario. The half-degree additional warming will lead to a shift toward higher extreme temperature in these five sites. For both1.5° and 2.0℃ scenarios, the number of weight-restriction days will increase significantly at 3 airports including Beijing, Shanghai, and Lasa. Urumqi will witness an increase of weight-restriction days only in 2.0℃ future.

Variational formulas and approximation theorems for the first eigenvalue in dimension one

Some complete variational formulas and approximation theorems for the first eigenvalue of elliptic operators in dimension one or a class of Markov chains are presented.