三维各向异性TI介质中的P/S波快速解耦技术及在弹性波逆时偏移中的应用

随着多分量采集技术的发展,弹性波逆时偏移技术在三维各向异性介质复杂地质构造成像中得到了广泛的应用.然而耦合的P波场和S波场,会在传播过程中产生串扰噪声,降低弹性波逆时偏移的成像精度.为了解决这一问题,本研究针对具有倾斜各向异性对称轴的三维横向各向同性(Transverse Isotropy,TI)介质,提出了一种矢量弹性波场快速解耦方法,可以有效提高偏移剖面的成像质量.该方法首先通过坐标转换,将观测系统坐标系的垂直轴旋转到TI介质的对称轴方向,在新坐标系下,根据具有垂直对称轴的三维横向各向同性(Vertical Transverse Isotropy,VTI)介质中的分解算子,推导出三维TI介质解耦算子表达式.接着引入一种在空间域快速计算分解波场的方法,来实现空间域矢量P波场和S波场分离,极大地提高了计算效率.最后,通过点积成像条件,将提出的P/S波分解方法引入到三维TI介质弹性波逆时偏移中,得到高精度的PP和PS成像.与以往的波场分解方法相比,本文方法具有数值稳定和计算效率高的特点.数值算例表明,应用上述三维TI分解算子得到的偏移剖面有效压制了噪声,提高了成像质量.

On the Reconstruction of Teachers’Role of Business English Reading Classroom Teaching Based on Literature Circle

Business English reading teaching under the mode of“literature circles”focuses on cultivating students’autonomy in reading,group cooperation,and the exchange of ideas among group members.In this teaching mode,teachers are no longer the masters of the reading classroom,but the helpers,participants,and researchers in the process of students’reading.The reconstruction of teachers’role can promote the benign development of relationship not only between teachers and students,but also between students and students,inject new impetus and vitality into the classroom,and improve students’reading literacy.

The Dilemma of Women’s Voices in the Post-Epidemic Era:Misconceptions of Feminism on Digital Media Platforms-The Example of Sina Weibo

Weibo,one of China’s largest digital media platforms,has become a major platform for women’s voices to fight for equality.However,misconceptions of feminism on Weibo have become obstacles to women’s voices,for which the platforms did not post women’s views prominently.From the perspective of women themselves,this paper adopted a questionnaire to study the misunderstanding of feminism and its impact on women’s expression on Weibo.

A Fractal Orifice-Throat Model for Seepage Characteristics of Multiscale Porous Media

The seepage characteristics of multiscale porous media is of considerable significance in many scientific and engineering fields.The Darcy permeability is one of the key macroscopic physical properties to characterize the seepage capacity of porous media.Therefore,based on the statistically fractal scaling law of porous media,fractal geometry is applied to model the multiscale pore structures.And a two-dimensional fractal orifice-throat model with multiscale and tortuous characteristics is proposed for the seepage flow through porous media.The analytical expression for Darcy permeability of porous media is derived,which is validated by comparing with available experimental data.The results show that the Darcy permeability is significantly influenced by porosity,orifice-throat fractal dimension,minimum to maximum diameter ratio,orifice-throat ratio and tortuosity fractal dimension.The present results are helpful for understanding the seepage mechanism of multiscale porous media,and may provide theoretical basis for unconventional oil and gas exploration and development,porous phase transition energy storage composites,CO2 geological sequestration,environmental protection and nuclear waste treatment,etc.

Attitudes Toward People Who Stutter in the Chinese Context: An Exploratory Study on the Impact of Knowledge Sources

The public’s attitudes can affect the experience of stuttering of people who stutter.This study investigated the attitudes held by the public about people who stutter in China.A web-based written survey with closed and open-ended questions was implemented to develop a rich understanding.One hundred and two respondents in 26 provinces and 3 municipalities provided comments on people who stutter in their life aspects such as personality,speech,social life,work,life participation,education,dating and marriage,capability,and communication skills.The predominantly negative attitudes towards the overall domains were identified.Attitudes to people who stutter varied according to the different sources of knowledge.Familiarity with people who stutter might reduce stereotypes.However,knowledge from the media might aggravate stereotypes.Implications and future research orientation were also discussed.

The Role of New Media in Communicating to Beneficiaries of Ngos Working in Kajiado County, Kenya

Organizations serving rural communities in Kenya have found use for media as a tool of replacement for personal interface in the daily communication with the beneficiaries of their programmes in deprived areas. The interactions between two non-governmental organizations （NGOs） and rural beneficiaries in Isinya, Kajiado County, provide case studies of how NGOs modernize their outreach via new media and how beneficiaries respond to the change. The research was not only concerned with the presence of information technology （IT） and online facilities in remote and deprived locations. It also evaluated responses to the replacement of person-to-person contact with technologies, such as social media, the Internet, Compact Disc-Read Only Memory （CD-ROMs）, and Digital Versatile Disc （DVDs）. Conducted in four focus groups, the research evaluated the uptake of new media technologies by beneficiaries following the transition, asked whether beneficiaries engaged with the materials being communicated, and assessed whether this confluence of technology and culture had eased the flow of communication, or unsettled it. Evidence of discomfort among the older （over 50-year-old） beneficiaries stemmed from fear of failure to master the technologies and a desire for a continuation of regular interpersonal interaction with the NGO field officers （whose field trips were scaled back in preference of computer-mediated communication）. However, younger （under 40-year-old） beneficiaries were less insistent on regular interpersonal visits and were appreciative of the use of technology, and of the building of Maarifa Centres to give the beneficiaries free access to internet, DVDs, and hard drive-based information materials. Another demographic, beneficiaries aged between 40 and 50 years old, said they were not comfortable with the change and wanted the interpersonal interaction to continue, but were open to a longer-term transition once the beneficiaries were all conversant with the uses of the new technologies. The study recommends a better managed transition that accommodated the beneficiaries’ fears, misgivings, and cultural preference for verbal, face-to-face consultation.

Habits on Social Networks at Workplace: A Survey of Motivations and Behaviour

This article explores the use of social networks by workers in Abidjan, Côte d’Ivoire, with particular emphasis on a descriptive or quantitative analysis aimed at understanding motivations and methods of use. More than five hundred and fifty questionnaires were distributed, highlighting workers’ preferred digital channels and platforms. The results indicate that the majority use social media through their mobile phones, with WhatsApp being the most popular app, followed by Facebook and LinkedIn. The study reveals that workers use social media for entertainment purposes and to develop professional and social relationships, with 55% unable to live without social media at work for recreational activities. In addition, 35% spend on average 1 to 2 hours on social networks, mainly between 12 p.m. and 2 p.m. It also appears that 46% believe that social networks moderately improve their productivity. These findings can guide marketing strategies, training, technology development and government policies related to the use of social media in the workplace.

Isolation and Identification of a Taxol-producing Endophytic Fungus Identified from Taxus media

[Objective] The aim was to isolate and identify a taxol-producing endophytic fungus from Taxus media. [Method] 32 strains of endophytic fungi were identified form the inner bark of T. media,and their fermentation products were detected by high performance liquid chromatography (HPLC). [Result] Through the screening,a strain of taxol-producing endophytic fungi M57 was obtained,which could produce 45-50 μg/L of taxol,and M57 was defined as Rhizopus sp. through morphological observation and 18S rDNA sequence analysis. [Conclusion] The finding of Rhizopus sp. M57 provided a promising strain for producing taxol with taxol-producing fungi fermentation process.

A Survey into Teachers＇ Roles in Web-based College English Autonomous Learning

The paper, with the backdrop of web-based autonomous learning put forward by the recent college English teaching reform, aims to explore teachers＇ roles in this learning process in students＇ perception through the means of questionnaires and interviews. It further analyzes the possible reasons why students perceive their teachers＇ roles in such a way, in the hope of providing some implications for web-based college English autonomous learning.

Teacher's Role in the Oral English Class

English speaking has been paid more attention today, especially in the age of globalization. Teachers are attempting to find out more effective methods to enhance the teaching results of English speaking. Facing the great demands and present difficulties of oral English classes, teachers have to conduct more study and practice to find out what roles that an oral English teacher has to take in the oral English classroom. Compared with the traditional teaching role in the English classroom, an oral English teacher has to fulfill more than one role in the classroom teaching so as to provide better learning conditions for students. Lacking more exposure to the real interaction with native speakers, students expect the oral English teacher to be a creator of the language environment. With various teaching and learning activities in the oral English classroom, the teacher has to be a good organizer to ensure every student to achieve improvement. An oral English teacher also has to correct students'language errors while ensuring the smooth progress of the classroom teaching. Only when an oral English teacher make clear what roles he or she has to take in the classroom can he or she achieve effective teaching.

The Exploration of the Helpful Roles Teacher Can Play to Help non-English Major Students Improve Their English Writing

It is commonly known that writing is an advanced skill which is essential in language learning but at the same time the most difficult task for learners. This paper is with the aim to explore helpful roles that teacher can play to help non-English major students improve their English writing, so as to help improve their writing ability in the author's context.

媒介接触下青年群体自主产品消费意愿的形成机理研究——基于S-O-R理论

培养青年群体自主产品消费意愿是实施扩大内需战略与深化供给侧结构性改革有机结合的有力抓手。基于S-O-R(刺激—有机体—反应)这一环境心理学理论,从“爱国情感”和“政府信任”两大路径出发构建媒介接触下的自主产品消费意愿模型,并将媒介细分为主流媒体和非主流媒体展开对比研究。基于结构方程模型的验证发现,主流媒体和社交媒体刺激了消费者的爱国情感和政府信任,最终影响自主产品消费意愿,且爱国情感路径下的作用更为突出。

Least Privileges and Role’s Inheritance of RBAC

The main advantages of role-based access control （RBAC） are able to support the well-known security principles and roles＇inheritance. But for there remains a lack of specific definition and the necessary formalization for RBAC, it is hard to realize RBAC in practical work. Our contribution here is to formalize the main relations of RBAC and take first step to propose concepts of action closure and deta closure of a role, based on which we got the specification and algorithm for the least privileges of a role. We propose that roles＇ inheritance should consist of inheritance of actions and inheritance of data, and then we got the inheritance of privileges among roles, which can also be supported by existing exploit tools.

Baeyer-Villiger oxidation of cyclic ketones utilizing potassium peroxydisulfate(K_2S_2O_8) or sodium perborate(NaBO_3) in acidic media

The efficient, green, facile, mild and straightforward conversion procedure for the oxidation of cyclic ketones to lactones at room temperature utilizing potassium peroxydisulfate （K2S2O8） in acidic media is satisfactory to high yields without using traditional chlorinated solvents is reported. This oxidative reagent is cheap and friendly environmental procedure for industrial purposes than use of organic peracids.

Role of P,S and B on Creep Behavior of Alloy 718

The doping of phosphorus, sulfur and boron in IN718 superalloy can remarkably influence the creep behavior. The modifications of the minor elements seem not to vary the stress exponent and the influences primarily concentrate on the effective diffusion coefficient. A pronounced beneficial interaction between P and B and a weaker detrimental interaction between P and S have been obtained. The preexponential frequency constant is proved to be strongly related with the creep activation energy because of the so-called compensation effect. The compensation temperature has been determined to be about 1080 K, which corresponds to the transformation temperature from rapidly coarsened γ'' phase to δ phase. It has been proposed that trace elements can influence the effective diffusion coefficient individually or cooperatively, which in turn either retard or speed the creep process.

Linear instability of the electrified free interface between two cylindrical shells of viscoelastic fluids through porous media

In this paper, we have discussed the linear stabil- ity analysis of the electrified surface separating two coaxial Oldroyd-B fluid layers confined between two impermeable rigid cylinders in the presence of both interfacial insoluble surfactant and surface charge through porous media. The case of long waves interfacial stability has been studied. The dispersion relation is solved numerically and hence the ef- fects of various parameters are illustrated graphically. Our results reveal that the influence of the physicochemical pa- rameterβ is to shrink the instability region of the surface and reduce the growth rate of the unstable normal modes. Such important effects of the surfactant on the shape of in- terfacial structures are more sensitive to the variation of the βcorresponding to non-Newtonian fluids-model compared with the Newtonian fluids model. In the case of long wave limit, it is demonstrated that increasing r, has a dual role in- fluence （de-stabilizing effects） depending on the viscosity of the core fluid. It has a destabilizing effect at the large values of the core fluid viscosity coefficient, while this role is ex- changed to a regularly stabilizing influence at small values of such coefficient.

Putative roles of cathepsin B in Alzheimer's disease pathology: the good, the bad, and the ugly in one?

Alzheimer＇s disease（AD）is a fatal progressive neurodegenerative disorder characterized by loss in memory,cognition,and executive function and activities of daily living.AD pathogenesis has been shown to involve loss of neurons and synapses,cholinergic deficits,amyloid-beta protein（Aβ）deposition,tau protein hyperphosphorylation, and neuroinflammation.

The role of DJ-1 complexes and catecholamine metabolism： relevance for familial and idiopathic Parkinson＇s disease

Autosomal recessive mutations in the PARK7 gene,which encodes for the protein DJ-1,result in a loss of function and are a cause of familial Parkinson’s disease（PD）,while increased wild-type DJ-1protein levels are associated with some forms of cancer.Several functions of DJ-1 have been described,with the greatest evidence indicating that DJ-1 is a redox-sensitive protein involved in the regulation of oxidative stress and cell survival.

Teachers＇ role in vocabulary teaching： Strategies for vocabulary teaching

Much research has been done on how to help students to improve their language skills of listening, speaking, reading, and writing, but how to help students with the acquisition of vocabulary which is essential to the development of language skills has been neglected. This paper is an attempt to explore the teacher＇s role in helping students with vocabulary acquisition. Word knowledge is discussed, selection of words to be taught, techniques for presentation and strategies for self-learning.

Forward modeling of ocean-bottom cable data and wave-mode separation in fluid–solid elastic media with irregular seabed

In marine seismic exploration, ocean-bottom cable techniques accurately record the multicomponent seismic wavefield; however, the seismic wave propagation in fluid–solid media cannot be simulated by a single wave equation. In addition, when the seabed interface is irregular, traditional finite-difference schemes cannot simulate the seismic wave propagation across the irregular seabed interface. Therefore, an acoustic–elastic forward modeling and vector-based P-and S-wave separation method is proposed. In this method, we divide the fluid–solid elastic media with irregular interface into orthogonal grids and map the irregular interface in the Cartesian coordinates system into a horizontal interface in the curvilinear coordinates system of the computational domain using coordinates transformation. The acoustic and elastic wave equations in the curvilinear coordinates system are applied to the fluid and solid medium, respectively. At the irregular interface, the two equations are combined into an acoustic–elastic equation in the curvilinear coordinates system. We next introduce a full staggered-grid scheme to improve the stability of the numerical simulation. Thus, separate P-and S-wave equations in the curvilinear coordinates system are derived to realize the P-and S-wave separation method.