水泥土搅拌桩桩身均匀性定量判定与评价方法

介绍一种用定量指标判定与评价水泥土搅拌桩桩身均匀性的方法。     

砂岩油藏水平井控液增油实践

塔河油田1区三叠系油藏是典型的底水油藏,进入2008年以来,随着综合含水的上升,油藏日产油水平、采油速度等指标开始明显下降,开发效果有所变差,稳产面临严峻挑战。通过加强油藏精细研究,深化油藏动态分析,实施控液治水的开发技术政策,有效的解决了制约油田稳产关健问题。研究结果对于大底水砂岩油藏开发具有重要意义。     

基于SBM模型的中国省际全要素能源效率和污染排放效率研究

本文使用处理非期望产出的SBM模型，利用2001．2010年省际面板数据计算中国30省份的能源效率和污染排放效率及影响因素。研究结果表明，中国整体的能源效率和排放效率均在低位运行，有下滑趋势，且排放效率表现相对低落。随着时间推移，各省份和全国的能源效率和排放效率差距也有扩大趋势。整个研究期间，北京、上海、广东、海南等四地的能源效率和排放效率值均为1，实现了资源节约、环境友好的双赢局面，其他地区在节能减排上仍存在程度不一的改善空间。Tobit模型的回归结果表明，第二产业比重越高，越不利于提高各省能源效率和排放效率；政府影响力对各省能源效率和排放效率的影响为负值；贸易依存度、人口密度对各省能源效率和排放效率有正向显著影响。最后，本文提出了有关政策建议。     

基于因子分析的新建本科院校公选课满意度研究

通过问卷调查，获得第一手资料，应用统计软件对数据进行处理。结合各指标的方差分析各指标的平均满意度，应用因子分析对原来十三项指标进行化简，建立新建本科院校学生公选课满意度的综合评价模型，并进行排序。结果表明，学生所学专业、公选课的性质是影响学生对公选课的满意度的主要因素。     

The validation of the E-Victimisation Scale (E-VS) and the E-Bullying Scale (E-BS) for adolescents

This study investigates the psychometric properties of the E-Victimisation Scale (E-VS) and E-Bullying Scale (E-BS) designed to assess Cyber Bullying among Chinese adolescents. Participants were 484 adolescents aged between 11–16 years randomly recruited from high schools within a region. Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) were applied to investigate the factorial structure of these scales. Reliability was examined by Cronbach’s alpha coefficients by sex. The convergent validity was investigated by correlations among these scales and the Centre for Epidemiological Studies-Depression for Children as well as the Zung’s Anxiety Scales. A single-factor model for the E-VS and a 2-factor model for the E-BS were resulted from the EFA with large factor loadings and about 47% and 56% of variance explained respectively. Cronhach’s alpha values provided evidence for good internal reliability with values ranging from 0.55 to 0.96. Correlations between the E-VS and Depression as well as Anxiety scales showed positive and significant relationships, however, the E-BS was only related to Depression. Psychometric evidence has shown that both E-VS and E-BS are valid instruments for measuring Cyber bullying behaviour and victimisation. Further studies are required on the test–retest reliability, discriminate validity, responsiveness, as well as normative information for standardisation.     

Design and analysis of UW-OFDM signals

Unique word-orthogonal frequency division multiplexing (UW-OFDM) is a novel signaling concept where the guard interval is implemented as a deterministic sequence, the so-called unique word. The UW is generated by introducing a certain level of redundancy in the frequency domain. Different data estimation strategies and the favourable bit error ratio (BER) performance of UW-OFDM, as well as comparisons to competing concepts have already extensively been discussed in previous papers. This work focuses on the different possibilities on how to generate UW-OFDM signals. The optimality of the two-step over the direct approach in systematic UW-OFDM is proved analytically, we present a heuristic algorithm that allows a fast numerical optimization of the redundant subcarrier positions, and we show that our original intuitive approach of spreading the redundant subcarriers in systematically encoded UW-OFDM by minimizing the mean redundant energy is practically also optimum w.r.t. transceiver based cost functions. Finally, we derive closed form approximations of the statistical symbol distributions on individual subcarriers as well as the redundant energy distribution and compare them with numerically found results.     

Fatigue strength of steel rollers with failure occurring at the weld root based on the local strain energy values: modelling and fatigue assessment

Weldments geometry with failures occurring at the weld toe or at the weld root cannot, by its nature, be precisely defined. Parameters such as bead shape and toe or root radius vary from joint to joint even in well-controlled manufacturing operations. The worst case configuration can be achieved by modelling as a sharp, zero radius, notch both the toe and the weld root. The intensity of asymptotic stress distributions obeying Williams’ solution is quantified by means of the Notch Stress Intensity Factors (NSIFs). For steel welded joints with failures originated from the weld roots, where the lack of penetration zone is treated as a crack-like notch, units for NSIFs are the same as conventional SIFs used in LEFM. The different dimensionality of NSIFs for different notch opening angles does not allow a direct comparison of failures occurring at the weld toe or at the weld root. In order to overcome the problem related to the variability of the V-notch opening angle, a simple scalar quantity, i.e. the value of the strain energy density (SED) averaged in the structural volume surrounding the notch tip, has been introduced. This energy is given in closed form on the basis of the relevant NSIFs for modes I, II and III. The radius R_c of the averaging zone is carefully identified with reference to conventional arc welding processes being equal to 0.28 mm for welded joints made of steel.The local-energy based criterion is applied here to steel welded rollers produced by Rulmeca and subjected to prevailing mode I (with failures at the weld root). The aim of the paper is firstly to describe the employed methodology for the fatigue assessment and secondly to show the first synthesis of fatigue data by means of local SED for a specific geometry.     

Notices

The expected number of maxima and level crossings of a continuous stationary Gaussian process and the discrete process obtained by sampling the continuous one are evaluated and compared. The ratio of these two values as a function of sampling rate for two classes of spectra is calculated. It is shown that the rule of thumb of sampling at twice the Nyquist frequency is a good one.     

Smartphone Addiction Inventory (SPAI): Psychometric properties and confirmatory factor analysis

The Smartphone Addiction Inventory (SPAI) was developed to assess smartphone addiction in Taiwanese university students. The purpose of the current research is to evaluate the factor structure and psychometric properties of the SPAI in Italian university students. A total of 485 university students (29.3% boys) completed the SPAI and the Young’s Internet Addiction Test (IAT).The proposed four-factor model of the SPAI-I was tested by computing CFA, and the results of the goodness of fit indices indicated an ambiguous solution. An exploratory-confirmatory cross validation strategy was applied for a better trimming of SPAI-I factorial structure. Results suggested a five-factor solution that explained 53% of the total variance (Time Spent, Compulsivity, Daily Life Interference, Craving, and Sleep Interference). Excellent internal consistency and five factor correlations were reported for the SPAI-I. This five-factor model showed good convergent validity with the Internet Addiction Disorder Test. Considering that evidence shows that overuse of a smartphone can be associated with adverse and problematic effects, the SPAI-I should be useful for determining its potential for the use in future research in Europe and for comparing the evaluation of smartphone overuse of young European people with other international Asiatic studies that have incorporated the SPAI.