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101.
崔利荣 《上海交通大学学报(英文版)》2016,21(4):509-512
Consistent high-quality and defect-free production is the demand of the day. The product recall not only increases engineering and manufacturing cost but also affects the quality and the reliability of the product in the eye of users. The monitoring and improvement of a manufacturing process are the strength of statistical process control. In this article we propose a process monitoring memory-based scheme for continuous data under the assumption of normality to detect small non-random shift patterns in any manufacturing or service process.The control limits for the proposed scheme are constructed. The in-control and out-of-control average run length(AVL) expressions have been derived for the performance evaluation of the proposed scheme. Robustness to non-normality has been tested after simulation study of the run length distribution of the proposed scheme, and the comparisons with Shewhart and exponentially weighted moving average(EWMA) schemes are presented for various gamma and t-distributions. The proposed scheme is effective and attractive as it has one design parameter which differentiates it from the traditional schemes. Finally, some suggestions and recommendations are made for the future work. 相似文献
102.
The simulation is an important means of performance evaluation of the computer architecture. Nowadays, the serial simulation of general purpose graphics processing unit (GPGPU) architecture is the main bottleneck for the simulation speed. To address this issue, we propose the intra-kernel parallelization on a multicore processor and the inter-kernel parallelization on a multiple-machine platform. We apply these two methods to the GPGPU-sim simulator. The intra-kernel parallelization method firstly parallelizes the serial simulation of multiple compute units in one cycle. Then it parallelizes the timing and functional simulation to reduce the performance loss caused by the synchronization between different compute units. The inter-kernel parallelization method divides multiple kernels of a CUDA program into several groups and distributes these groups across multiple simulation hosts to perform the simulation. Experimental results show that the intra-kernel parallelization method achieves a speed-up of up to 12 with a maximum error rate of 0.009 4% on a 32-core machine, and the inter-kernel parallelization method can accelerate the simulation by a factor of up to 3.9 with a maximum error rate of 0.11% on four simulation hosts. The orthogonality between these two methods allows us to combine them together on multiple multi-core hosts to get further performance improvements. 相似文献
103.
To get the accurate wave loads on wharf composite structure, the wave force on small-scale piles and the uplift force on lower
surface of caisson must be considered. Based on the Reynolds averaged Navier-Stokes (RANS) equations, the pore media theory
and the volume of fluid (VoF) method, a three-dimensional numerical model is established. The model has been developed to
simulate wave interaction with a composite structure including caisson, piles and deck. The numerical results agree very well
with the experimental data on total force. The spatial distributions of the non-dimensional wave height and the maximum of
wave pressure on surface of composite structure are presented and discussed. The effects of relative caisson length, relative
wave height and relative caisson height on horizontal wave force are given. The result indicates that the horizontal wave
force achieves maximum value at the relative caisson length of 0.18 and increases linearly with the increase of the relative
caisson and wave height. It is proved that the model is an accurate and efficient numerical tool to investigate different
problems of wave-structure interaction. 相似文献
104.
D.?Savitski V.?IvanovEmail author B.?Shyrokau T.?Pütz J.?De?Smet J.?Theunissen 《International Journal of Automotive Technology》2016,17(2):327-338
Functions of anti-lock braking for full electric vehicles (EV) with individually controlled wheel drive can be realized through conventional brake system actuating friction brakes and regenerative brake system actuating electric motors. To analyze advantages and limitations of both variants of anti-lock braking systems (ABS), the presented study introduces results of experimental investigations obtained from proving ground tests of all-wheel drive EV. The brake performance is assessed for three different configurations: hydraulic ABS; regenerative ABS only on the front axle; blended hydraulic and regenerative ABS on the front axle and hydraulic ABS on the rear axle. The hydraulic ABS is based on a rule-based controller, and the continuous regenerative ABS uses the gain-scheduled proportional-integral direct slip control with feedforward and feedback control parts. The results of tests on low-friction road surface demonstrated that all the ABS configurations guarantee considerable reduction of the brake distance compared to the vehicle without ABS. In addition, braking manoeuvres with the regenerative ABS are characterized by accurate tracking of the reference wheel slip that results in less oscillatory time profile of the vehicle deceleration and, as consequence, in better driving comfort. The results of the presented experimental investigations can be used in the process of selection of ABS architecture for upcoming generations of full electric vehicles with individual wheel drive. 相似文献
105.
Saeed?Abedi Ali?Akbar?Dehghan Ali?SaeidinezhadEmail author Mojtaba?Dehghan?Manshadi 《船舶与海洋工程学报》2016,15(1):8-15
A flow field around a streamlined body at an intermediate angle of incidence is dominated by cross-flow separation and vortical flow fields. The separated flow leads to a pair of vortices on the leeside of the body; therefore, it is essential to accurately determine this pair and estimate its size and location. This study utilizes the element-based finite volume method based on RANS equations to compute a 3D axisymmetric flow around a SUBOFF bare submarined hull. Cross-flow vortex structures are then numerically simulated and compared for a submarine with SUBOFF and DRDC STR bows. Computed results of pressure and shear stress distribution on the hull surface and the strength and locations of the vortex structures are presented at an intermediate incidence angle of 20°. A wind tunnel experiment is also conducted to experimentally visualize the vortex structures and measure their core locations. These experimental results are compared with the numerical data, and a good agreement is found. 相似文献
106.
In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the Arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail. 相似文献
107.
A transit service quality study based on cluster analysis was performed to extract detailed customer profiles sharing similar appraisals concerning the service. This approach made it possible to detect specific requirements and needs regarding the quality of service and to personalize the marketing strategy. Data from various customer satisfaction surveys conducted by the Transport Consortium of Granada (Spain) were analyzed to distinguish these groups; a decision tree methodology was used to identify the most important service quality attributes influencing passengers’ overall evaluations. Cluster analysis identified four groups of passengers. Comparisons using decision trees among the overall sample of all users and the different groups of passengers identified by cluster analysis led to the discovery of differences in the key attributes encompassed by perceived quality. 相似文献
108.
Recent longitudinal studies of household car ownership have examined factors associated with increases and decreases in car ownership level. The contribution of this panel data analysis is to identify the predictors of different types of car ownership level change (zero to one car, one to two cars and vice versa) and demonstrate that these are quite different in nature. The study develops a large scale data set (n = 19,334), drawing on the first two waves (2009–2011) of the UK Household Longitudinal Study (UKHLS). This has enabled the generation of a comprehensive set of life event and spatial context variables. Changes to composition of households (people arriving and leaving) and to driving licence availability are the strongest predictors of car ownership level changes, followed by employment status and income changes. Households were found to be more likely to relinquish cars in association with an income reduction than they were to acquire cars in association with an income gain. This may be attributed to the economic recession of the time. The effect of having children differs according to car ownership state with it increasing the probability of acquiring a car for non-car owners and increasing the probability of relinquishing a car for two car owners. Sensitivity to spatial context is demonstrated by poorer access to public transport predicting higher probability of a non-car owning household acquiring a car and lower probability of a one-car owning household relinquishing a car. While previous panel studies have had to rely on comparatively small samples, the large scale nature of the UKHLS has provided robust and comprehensive evidence of the factors that determine different car ownership level changes. 相似文献
109.
Xinyu ?Cao 《Transportation》2009,36(2):207-222
The causality issue has become one of the key questions in the debate over the relationships between the built environment
and travel behavior. Although previous studies have tested statistical and/or practical significance of the built environment
on travel behavior, few have quantified the relative roles of the built environment and residential self-selection in influencing
travel behavior. Using 1,479 residents living in four traditional and four suburban neighborhoods in Northern California,
this study explores the causal effect of neighborhood type on driving behavior and its relative contribution to the total
influence of neighborhood type. Specifically, this study applied Heckman’s sample selection model to separate the effect of
the built environment itself and the effect of self-selection. The results showed that, on average, the effect of neighborhood
type itself on driving distance was 25.8 miles per week, which accounted for more than three quarters of the total influence
of neighborhood type and 16% of individuals’ overall vehicle miles driven. These results suggest that the effect of the built
environment on driving behavior outweighs that of self-selection. This paper also discussed the advantages and weaknesses
of applying the Heckman’s model to address the self-selection issue.
相似文献
Xinyu (Jason) CaoEmail: |
110.
The concept of heterogeneity in choice structure is applied in this study to examine individuals’ action space, which is defined
in terms of the reported frequencies of visits. A disaggregate model system that predicts the frequency of visits is condensed
using a nested logit model with multiple choice structures. 相似文献