社会心态量表测评中国大学生群体的效度和信度检验

目的:对社会心态量表(SMS)进行中文版修订,检验其在中国大学生群体中的效度和信度。方法:选取690名大学生初测,进行SMS条目分析、平行分析和探索性因子分析;正式调查抽取1179名大学生对SMS进行验证性因子分析与信度分析,受测者同时完成中国大五人格问卷简式版(CBF-PI-B)、一般归属感量表(GBS)检验效标关联效度。结果:探索性因子分析得到不安全感、亲社会性、竞争性、归属感、性倾向、游戏性6个因子,修订后49个条目SMS的累计方差贡献率为45.85%;验证性因子分析显示模型拟合良好(χ^(2)/df=4.10,CFI=0.95,TLI=0.93,GFI=0.95,AGFI=0.93,NFI=0.93,IFI=0.95,RMSEA=0.05,SRMR=0.05),再次修订后48个条目SMS的累计方差贡献率为47.30%;中文修订版SMS各指标与效标得分的相关系数0.11~0.69(P<0.001);6个分量表的Cronbachα系数0.65~0.89,分半信度0.64~0.90。结论:修订后的中文版SMS测量大学生的社会心态显示有良好的效度和信度。

Core shift limitation in investment casting process of hollow turbine blade

The deviation in wall thickness caused by core shift during the investment casting process significantly impacts the strength and service life of hollow turbine blades.To address this issue,a core shift limitation method is developed in this study.Firstly,a shift model is established based on computational fluid dynamics and motion simulation to predict the movement of the ceramic core in investment casting process.Subsequently,utilizing this model,an optimization method for fixturing layout inside the refractory ceramic shell is devised for the ceramic core.The casting experiment demonstrates that by utilizing the optimized fixture layout,not only can core shift during the investment casting pouring process be effectively controlled,but also the maximum wall thickness error of the blade can be reduced by 42.02%.In addition,the core shift prediction is also validated,with a prediction error of less than 26.9%.

Performance of a single-stage Linde-Hampson refrigerator operating with binary refrigerants at the temperature level of-60°C

The optimization of the performance of a single-stage Linde-Hampson refrigerator （LHR） operating with six different binary refrigerants （R23/R134a, R23/R227ea, R23/R236ea, R170/R290, R170/R600a and R170/R600） with ozone depletion potentials （ODPs） of zero was conducted using a new approach at the temperature level of-60℃. Among these binary refrig- erants, the 0.55 and the 0.6 mole fractions of R23 for R23/R236ea are the most prospective nonflammable ones for the medium and low suction pressure compressors, respectively. For these two kinds of compressors, the 0.6 and the 0.65 mole fractions of R170 for R 170/R600, respectively, are the most prospective binary refrigerants with low global warming potentials （GWPs）. The results of optimization of pressure levels indicate that the optimum low pressure value for coefficients of performance （COP） is achieved when the minimum temperature differences occur at both the hot and the cold ends of the recuperator at a specified composition and pressure ratio. Two useful new parameters, the entropy production per unit heat recuperated and the ratio of heat recuperating capacity to the power consumption of the compression, were introduced to analyze the exergy loss ratio in the recuperator. The new approach employed in this paper also suggests a promising application even to the optimization of the performance with multi-component refrigerants.

A wall-thickness compensation strategy for wax pattern of hollow turbine blade

As an important index affecting the aerodynamic performance and the structural strength of hollow turbine blades, the wall-thickness precision of the blade is mainly inherited from the positional relationship between the corresponding wax pattern and the internal ceramic core.However, due to locating errors, the actual position of ceramic core is always deviated from the ideal position, which makes it difficult to guarantee the wall-thickness precision of the wax pattern.To solve this problem, a wall-thickness compensation strategy is proposed in this paper. Firstly,based on the industrial computed tomography(ICT) technique and curve matching algorithms, a model reconstruction method is developed, with which the 3D model of a trial wax pattern can be easily constructed. After that, focusing on eliminating the wall-thickness errors of the trial wax pattern, an optimization method for the pose of the ceramic core in the wax pattern is proposed. Then, by mapping the optimal pose of the ceramic core to length adjustments of the locating rods, the wall-thickness errors of the wax pattern can be greatly reduced. A case study is also given to illustrate the effectiveness of the proposed compensation strategy.

Model reconstruction for worn blades based on hybrid surface registrations

Model reconstruction is crucial in blade repair because it directly determines the shape precision and finish of a repaired surface.However,owing to insufficient surface data pertaining to defective regions and the unique deformation caused by harsh environments,modeling a worn blade remains difficult.Hence,a model reconstruction method for worn blades is developed in this study.Unlike conventional methods of constructing and interpolating sectional curves,the proposed method focuses on modifying a nominal computer aided design(CAD)model to reconstruct the worn blade.Through weighted rigid registration and constraint-based non-rigid registration,the design surface extracted from the nominal CAD model can be deformed to align with the surface data of the worn blade without a significant loss of its initial shape.Verification results show that the deformed design surface exhibits sufficient smoothness and accuracy for guiding tool path generation in the subsequent blade repair.