A Model for Cross-Domain Opinion Target Extraction in Sentiment Analysis

Opinion target extraction is one of the core tasks in sentiment analysis on text data. In recent years, dependency parser–based approaches have been commonly studied for opinion target extraction. However, dependency parsers are limited by language and grammatical constraints. Therefore, in this work, a sequential pattern-based rule mining model, which does not have such constraints, is proposed for cross-domain opinion target extraction from product reviews in unknown domains. Thus, knowing the domain of reviews while extracting opinion targets becomes no longer a requirement. The proposed model also reveals the difference between the concepts of opinion target and aspect, which are commonly confused in the literature. The model consists of two stages. In the first stage, the aspects of reviews are extracted from the target domain using the rules automatically generated from source domains. The aspects are also transferred from the source domains to a target domain. Moreover, aspect pruning is applied to further improve the performance of aspect extraction. In the second stage, the opinion target is extracted among the aspects extracted at the former stage using the rules automatically generated for opinion target extraction. The proposed model was evaluated on several benchmark datasets in different domains and compared against the literature. The experimental results revealed that the opinion targets of the reviews in unknown domains can be extracted with higher accuracy than those of the previous works.     

XNC-98催化剂甲醇合成本征动力学

在等温积分反应器中研究了XNC-98催化剂上甲醇合成反应本征动力学.实验压力为4~8MPa,空速7000~13000h-1,反应温度200~260℃.实验采用粒度为0.154~0.198mm的细颗粒催化剂.选取以各组分逸度表示的CO、CO2加氢合成甲醇的Langmuir-Hinshelwood本征动力学模型.采用正交实验设计,实验测定了25组数据,用全局通用算法结合马夸特算法确定动力学模型参数.残差分析和统计检验表明,动力学模型是适宜的.随温度升高,反应器出口甲醇浓度、CO和CO2转化率先增加后降低,在4~8MPa下,230~245℃为较佳反应温度范围:随着反应压力的提高,反应器出口甲醇浓度、CO和CO2转化率都有显著增加,提高反应压力能够有效提高反应器的生产能力.     

基于遥感技术的城市下垫面参数与热环境关系的研究——以北京市朝阳区为例

城市热岛(UHI)不仅直接关系到城市人居环境质量和居民健康状况,同时还对城市能源消耗、生态系统过程演变、生物物候以及城市经济可持续发展有着深远的影响。以北京市朝阳区2002—2017年夏季4期Landsat系列遥感影像为数据,采用大气反演法,对15年间朝阳区城市地表温度(LST)时空变化进行分析,发现15年间朝阳区城市热岛比例指数上升迅速,热岛效应逐年加剧。进一步研究表明,城市地表温度与归一化植被指数(NDVI)及归一化建筑指数(NDBI)密切相关:地表温度与NDBI正相关,NDBI指数每升高0.1,地表升温0.79～2.37°C;与NDVI指数负相关,NDVI指数每提高0.1,地表降温0.4～0.77°C。本研究可为城市规划建设与城市绿地营建提供科学具体的参考指导依据,并促进生态可持续发展与人居环境改善。     

Comprehensive evaluation of new urban transportation systems by AHP

Many different kinds of transportation systems such as ‘group rapid transit’, etc., have recently been presented as ideal urban public transportation systems. When planning to introduce such a new transportation system into a city, it is necessary to select the most desirable system for that city from those that have been proposed. The comprehensive evaluation of transportation systems must reflect various aspects such as the costs of construction and maintenance and the viewpoints or both the system users and the local inhabitants. This makes it one of the most difficult and yet vitally important problems in public transportation planning. The analytic hierarchy process (AHP) developed by T. L Saaty is straightforward and has the feature that it can deal with both qualitative and quantitative factors at the same time, and it is suitable for applying to complex evaluation problems, In this paper, three transportation systems are proposed for one of the newly planned towns in Kansai Cultural and Academic Research Complexes, and a comprehensive evaluation of these systems is performed by applying the AHP. It has been proved through the process of evaluation that information which is very useful in reaching a consensus for choosing a system can be obtained.     

Inverse Capacitance-Voltage Characteristics of Bi3.25La0.75Ti3O12 Thin Film Pulsed Laser Deposited on Thermally Oxidized n-Type Si Substrates

Comparative studies on the electrical properties of a metal-ferroelectric-insulator-semiconductor field effect transistor were conducted using pulsed laser ablated ferroelectric Bi_3.25La_0.75Ti₃O₁₂ (BLT) thin films deposited on SiO₂/Si substrates with different SiO₂ thicknesses. The SiO₂ layer was prepared on n-type Si substrates by dry oxidation at a temperature of 800°C. Small angle x-ray reflectivity studies were used to measure the SiO₂ thickness. The capacitance-voltage (C-V) measurements revealed that the films showed good interfacial properties. Shifts in flatband voltages were observable, but were effectively reduced by deposition of the ferroelectric films. Au/BLT/SiO₂/Si diodes with 8 nm SiO₂ layer showed to be stable with relatively large memory window values of about 0.3 V, 2.5 V, 5.0 V, and 7.0 V, at increasing bias voltages of ±5 V, ±7 V, ±10 V, and ±12 V, respectively.     

Model to evaluate the optimal mix of traffic types under environmental constraints in a large city

A model is developed to determine the optimal mix of traffic types between zones in a large city, provided the distribution of person-trips by purpose is given. The utilization ratio of each of the following four traffic types are determined: train, bus, taxi and private car. The model is a linear-programming model, where the generalized cost obtained as a sum of the trip cost and the travel time converted into a money term is minimized under various constraints, such as the capacity of each transportation facility and the permissible amount of pollutant emission. The outcomes of such drastic policies as the reduction of the total amount of car traffic or the reinforcement of pollution control can thus be easily simulated. By applying to the data of the OD survey in 1970 in Osaka, it is confirmed that the model can explain fairly well the actual situations of modal split among different traffic means. The impact of highly enforced environmental protection control is also evaluated by finding the optimum solution to the model.     

Thermodynamics of Ti in liquid steels and slags

Thermodynamics of Ti in liquid steels and slags was studied in order to establish a data base for the prediction of TiO_x and TiN formation in liquid steels.The interaction parameters between Ti and i（i = Cr,Ti,Al, Si,Ni,Mo,Nb,N,O） in liquid iron and the equilibrium constants for the formation of TiN and TiO_x in liquid iron were determined as a function of temperature.In view of high Ti yield during ladle treatment,thermodynamics of titanium oxides in ladle slags was studied as well.Activity coefficient and redox equilibrium of TiO_x in MgO saturated CaO-Al₂O₃ slag are also discussed by measuring the distribution ratio of Ti between slag and iron melts and the Ti³⁺/Ti⁴⁺ ratio in slag at 1 873 K.     

均匀电场对沿波纹壁面下落液体薄膜流动稳定性的影响

此文基于加权残数积分边界层(WRIBL,Weighted-residual Jntegral Boundary-layer)模型,推导出描述电场作用下的沿波纹壁面下落的二维液膜流动的演化方程,分析了电场和壁面结构对稳定性的影响以及定常流动的特性.在壁面振幅较小的情况下,毛细作用促使薄膜更稳定,而电场则使其流动的失稳,此文提出了这两种作用的平衡条件,并说明壁面结构的引入可以加剧这两方面的效应.对定常流动的分析说明了表面波相对振幅和与壁面的相位差随物理参数的变化情况,并显示电场对流场共振现象有抑制作用.     

Prediction of characteristic blast-induced vibration frequency during underground excavation by using wavelet transform

Blast-induced vibration produces a very complex signal, and it is very important to work out environmental problems induced by blasting. In this study, blasting vibration signals were measured during underground excavation in carbonaceous shale by using vibration pickup CB-30 and FFT analyzer AD-3523. Then, wavelet analysis on the measured results was carried out to identify frequency bands reflecting changes of blasting vibration parameters such as vibration velocity and energy in different frequency bands. Frequency characteristics are then discussed in view of blast source distance and charge weight per delay. From analysis of results, it can be found that peak velocity and energy of blasting vibration in frequency band of 62.5–125 Hz were larger than ones in other bands, indicating the similarity to characteristics in the distribution band (31–130 Hz) of main vibration frequency. Most frequency bands were affected by blasting source distance, and the frequency band of 0–62.5 Hz reflected the change of charge weight per delay. By presenting a simplified method to predict main vibration frequency, this research may provide significant reference for future blasting engineering.     

非均匀壁厚塑件的充填不平衡现象

壁厚不均是引起注塑制品缺陷的重要原因之一。为研究壁厚对注塑模内熔体充填平衡性的影响,文章应用可视化实验和数值模拟的方法,以壁厚串联式和壁厚并联式2种结构作为模型,分别对其充填规律进行分析。研究发现:塑件壁厚的不均匀性对注塑流动过程影响很大,不同壁厚区域的熔体会有明显速度差,成型制品易产生熔接线、收缩、应力集中等缺陷。