Microstructural characteristics and mechanical properties of bobbin-tool friction stir welded 2024-T3 aluminum alloy

Cold-rolled 2024-T3 sheet alloy was subjected to bobbin-tool friction stir welding (BTFSW). The microstructural characteristics and mechanical properties of the nugget zone in the as-welded state were investigated. The results show that the equiaxed grain size of BTFSW 2024-T3 alloy decreases from 7.6 to 2.8 μm as the welding speed is increased from 80 to 120 mm/min; in addition, fine grains are generated in the nugget zone and the size distribution is non-uniform. All Al₂CuMg (S') precipitates dissolve into the Al matrix, whereas Mn-rich phases confirmed as T phases (Al₂₀Cu₂Mn₃, Al₆Mn, or Al₃Mn) remain unchanged. The optimized parameters for BTFSW are verified as the rotation speed of 350 r/min and the travel speed of 100 mm/min. The variations in precipitation and dislocation play more important roles than grain size in the nugget zone with respect to influencing the mechanical properties during the BTFSW process. After the BTFSW process, the fracture mode of base material 2024-T3 alloy transforms from ductile rupture to ductile-brittle mixed fracture.     

考虑主路左转延误的主路优先交叉口信号设置流量阈值

为了进一步完善主路优先交叉口信号灯设置流量条件,考虑了主路左转车流延误对交叉口信号灯设置条件的影响.通过分析主路左转车流在信号灯设置前后的交通特性,利用控制延误方法和Webster方法的研究思路,分别建立主路左转车流在信号灯设置前后的车均延误改进模型.从交叉口交通运行效率的角度出发,以交叉口车均延误作为判别指标,建立信号灯设置前后交叉口等车均延误曲线,以此曲线作为判断交叉口是否需要设置信号灯的阈值条件,同时还给出了不同主路左转车流比例下的流量阈值.与美国MUTCD提出的阈值曲线相比,考虑左转车流延误影响的流量阈值曲线更符合我国主路优先交叉口交通特性,具有更强的实用性.     

Phase transition in the subducted oceanic lithosphere and generation of the subduction zone magma

Two metamorphic processes, i.e. subsolidus dehydration and partial melting occurring in MORB, metasediments and peridotite of subducted oceanic lithosphere are discussed on the basis of available experimental work and phase equilibrium modeling. Phase diagrams of hydrous MORB show that in most cold subduction P-T （pressure-temperature） regimes a large portion of water in the basic layer has released below the onset of blueschist facies （〈 20 km）, and at a depth （60--70 km） of transition from lawsonite blueschist to lawsonite eclogite facies through glaucophane dehydration; only a smaller portion of water will escape from the slab through dehydration of lawsonite and chloritoid in the depth range suitable for arc magma formation; and a very small portion of water stored in lawsonite and phengite will fade into the deeper mantle. The role of amphibole for arc magma formation is still arguable. In cold subduction P-Tregimes, the dehydration of chlorite and talc in AI-poor metasediments, and chloritoid and carpholite in AI-rich metapelites at a depth around 80--100 km will make some con- tributions to the formation of arc magma. Comparatively, dehydration of serpentine in hydrated peri- dotite occurs at depths of 120--180 km, playing an important role in the arc magmatism. Subduction of oceanic crust along warm P-T regimes will cross the solidi at a depth over 80 km, resulting in partial melting under fluid-saturated and fluid-absent conditions in the metasediments involving biotite and phengite, and in the basic rocks involving epidote and amphibole. The melt compositions of the basic crust are adakitic at pressures 〈 3.0 GPa, but become peraluminous granitic at higher pressures.     

Bi_(2-x)Pr_xSr_2Ca_2Cu_3O_y超导体的研究

本文报导在零电阻温度为83K的Bi-Sr-Ca-Cu-O超导体中以不同含量Pr替代Bi的样品制备工艺、超导性能测试、X射线衍射及电镜的测量。测试表明Bi_(2-x)z Pr_x Sr_2 Ca_2 Cu_3 O_y中的Pr的摩尔含量x<0.2时样品的T_c在77K以上。这些样品随Pr含量的增加晶胞常数b,c有所增大,而a略有减小趋势。     

Sentiment Analysis of Code-Mixed Bambara-French Social Media Text Using Deep Learning Techniques

The global growth of the Internet and the rapid expansion of social networks such as Facebook make multilingual sentiment analysis of social media content very necessary. This paper performs the first sentiment analysis on code-mixed Bambara-French Facebook comments. We develop four Long Short-term Memory (LSTM)-based models and two Convolutional Neural Network (CNN)-based models, and use these six models, Naïve Bayes, and Support Vector Machines (SVM) to conduct experiments on a constituted dataset. Social media text written in Bambara is scarce. To mitigate this weakness, this paper uses dictionaries of character and word indexes to produce character and word embedding in place of pre-trained word vectors. We investigate the effect of comment length on the models and perform a comparison among them. The best performing model is a one-layer CNN deep learning model with an accuracy of 83.23 %.     

Analysis of fragrance composition in three cultivars of <Emphasis Type="Italic">Osmanthus fragrans</Emphasis> Albus group flower by gas chromatography-mass spectrometry

With supercritical CO2 fluid extraction(SCFE), essential oil was extracted from three cultivars of Xianning osmanthus. The fresh osmanthus flower was processed with a petroleum ether digestion method to produce the extractum. The yields of essential oil and extractum were 0.19 % and 0.13 % (m/m) respectively. The essential oil and fragrance composition and content extracted were analyzed with gas chromatography-mass spectrometer (GC-MS). The result showed that essential oil contained 36.99%(area/total area) of ionone, ionol and 13.11% of linalool; ionone and ionol contained in extractum were as high as up to 33.33%, while linalool up to 21.92%. Whether essential oil or extractum contains only about 40% fat acid and other ester matters. None of environmental estrogen (phthalic ester) was found in fragrance ingredients. The result also showed that the quality of O. fragrans Albus group fragrance in Xianning is better than that produced in Hangzhou and Anhui districts.     

ISTC： A New Method for Clustering Search Results

A new common phrase scoring method is proposed according to term frequency-inverse document frequency （TFIDF） and independence of the phrase. Combining the two properties can help identify more reasonable common phrases, which improve the accuracy of clustering. Also, the equation to measure the in-dependence of a phrase is proposed in this paper. The new algorithm which improves suffix tree clustering algorithm （STC） is named as improved suffix tree clustering （ISTC）. To validate the proposed algorithm, a prototype system is implemented and used to cluster several groups of web search results obtained from Google search engine. Experimental results show that the improved algorithm offers higher accuracy than traditional suffix tree clustering.     

Wavelet fractal character of overlapping signal

A new method based on the combining of the wavelet theory with the fractal theory and named wavelet fractal peak position method (WFPPM) is introduced to extract the number of the components and the relevant peak positions from overlapping signals in chemistry .The overlapping signal is first transformed into continuous wavelet transform value of time domain in certain dilation range via continuous wavelet transform (CWT),and then changed into capacity dimensions (Dc),The number of the components and the relevant positions of overlapping peaks can be identified easily according to the change of Dc.An investigation concerning the influence of different dilation ranges on the peak positions extracted by WFPPM is also provided .Studies show that the WFPPM is an efficient tool for extracting the peak positions and identifying the number of peaks from unresoloved signals,even when this kind of overlapping is significantly serious,Relative errors of lless than 1.0% in peak positions are found when WFPPM is used in the processing of the cadmium (Ⅱ)-indium(Ⅲ) mixture system .The analytical results demonstrate that the desired peak positions can be extracted conveniently ,accurately and rapidly from an unresoled signal via WFPPM,Tremendous developing and applications based on currently reported WFPPM in extracting overlapping signals would be expected in the near future.     

基于MapInfo的房产信息管理——以太原师范学院中区为例

文章讨论基于MapInfo软件建立房产信息空间数据库的方法，通过数据库的设计、数据的采集、图形矢量化、数据编辑处理来完成空间数据库的建立，并对房产信息进行查询、统计、分析等，为校园各级管理部门日常工作提供方便快捷的服务。     

肾癌淋巴结切除术的进展

本文对肾癌治疗中淋巴结切除的问题作了回顾性总结，当前，在肾癌术中作出行淋巴结切除术的决定仍是复杂的。尽管如此，对那些有淋巴结转移高风险或者已有明确淋巴结转移，但没有远处转移的患者来说，淋巴结切除术仍有可能起到根治的作用。我们也探讨了腹腔镜肾癌根治术和保留肾单位肾癌切除术中淋巴结切除术的原则，一般情况下，不采用典型区域淋巴结切除术。