Search results

This review aims to give a critical view of the wheel/rail high frequency vibration-induced vibration fatigue in railway bogie.

Vibration fatigue of railway bogie arising from the wheel/rail high frequency vibration has become the main concern of railway operators. Previous reviews usually focused on the formation mechanism of wheel/rail high frequency vibration. This paper thus gives a critical review of the vibration fatigue of railway bogie owing to the short-pitch irregularities-induced high frequency vibration, including a brief introduction of short-pitch irregularities, associated high frequency vibration in railway bogie, typical vibration fatigue failure cases of railway bogie and methodologies used for the assessment of vibration fatigue and research gaps.

The results showed that the resulting excitation frequencies of short-pitch irregularity vary substantially due to different track types and formation mechanisms. The axle box-mounted components are much more vulnerable to vibration fatigue compared with other components. The wheel polygonal wear and rail corrugation-induced high frequency vibration is the main driving force of fatigue failure, and the fatigue crack usually initiates from the defect of the weld seam. Vibration spectrum for attachments of railway bogie defined in the standard underestimates the vibration level arising from the short-pitch irregularities. The current investigations on vibration fatigue mainly focus on the methods to improve the accuracy of fatigue damage assessment, and a systematical design method for vibration fatigue remains a huge gap to improve the survival probability when the rail vehicle is subjected to vibration fatigue.

The research can facilitate the development of a new methodology to improve the fatigue life of railway vehicles when subjected to wheel/rail high frequency vibration.

This study aims to assess the vibrational behavior of a large transport airship based on finite element (FE) simulation and modal testing of its scaled model.

A full-size parametric FE model of the airframe was established according to the structural layout of the composite beam-cable airframe of the airship, and vibrational analysis of the airframe was conducted. The influence of cable pre-tension load on the inherent properties of the airframe was investigated. Based on the simplification of the full-size FE model, scaled numerical and test models of the airframe, with a geometric scale factor of 1:50, were established and built.

The simulation and test results of the scaled models indicated that the mode shapes of the full-size and scaled models were similar. The natural frequencies of both the full-size and scaled models complied with the theoretical similarity relation of the frequency response.

This study demonstrated that the vibrational test results of the scaled model with very large scaling can be used to characterize the modal properties of the beam-cable airframe of a large transport airship.

The purpose of this study to analyze the plastic anisotropy of 6061 aluminum alloy with finite deformation using crystal plasticity finite element method.

A representative volume element (RVE) model was constructed by Voronoi tessellation. In this model, grain shapes, grain orientations and distribution of grains were involved. The mechanical response of the component under composite loading was tested using specify cruciform specimen. Moreover, different stress and strain states in the specific central region were analyzed to reveal the effects of complex loading.

We calculated the influence of misorientation of adjacent grains as well as the evolution of the micro structure’s plastic deformation on the macroscopic deformation of the structure. Geometry design for the cruciform specimen helps obtain a homogenous distribution of the stress and strain at the specimen center. In this process, the initial grain orientation is also an important factor, and the larger misorientations between special grains may cause greater stress concentration.

The influence of micro-scale factors on macro-scale plastic anisotropy of AA6061 is analyzed using RVE model and cruciform specimen, and they offer a reference for related research.

Discusses the 6th ITCRR, its breadth of textile and clothing research activity, plus the encouragement given to workers in this field and its related areas. States that, within the newer research areas under the microscope of the community involved, technical textiles focuses on new, ‘smart’ garments and the initiatives in this field in both the UK and the international community at large. Covers this subject at length.

This paper aims to propose a method for measuring the rotation of moving body during parabolic flight using camera.

An orthogonal matrix used to calculate the Euler angles of rotation is solved by means of singular value decomposition. The translation velocity and position of moving body are measured by a binocular camera system.

The experiment is executed in a jet aircraft to simulate micro-gravity during parabolic flight. And the human moving body is regarded as a rigid body. The results show that this method can calculate the angles effectively.

This work is useful for calculation and monitoring body’s motion in space.

The paper gives a method which measures the rotation of a rigid body under the microgravity by a binocular camera to modify the measurement error of the interferometer.

The purpose of this paper is to study the effects of dimple geometries and arrangements on the heat transfer enhancement in a dimple jacketed heat exchanger.

For the purpose of this paper, with the experimental validated numerical model, this paper carries out numerical simulations of both single dimples with different geometries and the whole dimple jacketed heat exchanger with different dimple arrangements. For a single dimple, its secondary vortex flow, temperature differences and the pressure drop performance for different geometries are analyzed. For the whole dimple jacketed heat exchanger, the heat transfer and pressure drop performances are investigated by comparing the no dimple, triangular and rectangular dimple arrangements.

Results show that dimples can improve the heat transfer efficiency compared with conventional jacketed heat exchanger, and specific geometries and arrangement of dimples for better heat transfer performance are figured out.

This paper considers both dimple geometries and arrangements, which can be useful for further applications in specific integrated devices or similar applications.

The purpose of this paper is to analyze the phase coil connections and winding factors of flux‐switching permanent magnet (FSPM) brushless AC machines with all poles and alternate poles wound, and different combinations of stator and rotor pole numbers.

The coil‐emf vectors, which are widely used for analyzing the conventional fractional‐slot PM machines with non‐overlapping windings, are employed for FSPM machines.

Although the coil‐emf vectors have been employed to obtain coil connections in the conventional fractional‐slot PM machines, they are different in FSPM machines. It is mainly due to different polarities in the stator of FSPM machines. In addition, from the coil‐emf vectors it is able to predict whether the back‐emf waveforms are symmetrical or asymmetric.

This is the first time that coil‐emf vectors are used to determine the coil connections and winding factors in FSPM machines with different topologies and combination of stator and rotor pole numbers.

The brake connector of an automobile is one important part in the brake system. How to measure the matching surface quality is a problem, because the matching surface is a cone surface and has a deep aperture structure.

A new measurement system is presented which could assure illumination and image with a special beam splitter. The worker could observe the matching surface by better image.

More objective evaluation is given with image processing method.

Now, this measurement system is used by Toyota (Tianjin) company and satisfied result is obtained.

This paper is an original work and focuses on an important issue in automobile production.

The number of farms engaged in grain production in China has been declining in recent years. Limited efforts have been devoted to examine why producers quit from grain production and how such exits affect China's grain output. Such information, however, is invaluable in understanding whether the exit from grain production should be encouraged and if so, how. The purpose of this paper is to identify the factors that influence farmers' decision to quit from grain production, with a view to drawing implications for devising policies to deal with such exits.

Both descriptive statistics and econometric techniques are used to analyse a set of unique and comprehensive farm‐level survey data to identify key factors that affect farmers' decision to quit from grain production.

Key factors that influence a farm to quit from, or stay in, grain production include: family size, the share of farming labour out of total family labour, per capita arable land, the proportion of land used for grain production, the share of family income from grains. It was also found that the level of grain prices and the sunk cost in farming, chiefly in grain production, also affect the likelihood that a household will stay or exit from grain production. Further, farmers in more economically developed regions are more likely to quit from grain production.

The paper's findings clearly indicate that farms with a larger scale of grain production and earning higher income from grain are the major contributors to China's grain production. Potential exists for China to raise its total grain output if the land from those exiting farmers is readily made available to larger producers, enabling them to further benefit from the economies of scale.

The purpose of this paper is to probe the external visibility of the web sites of all seven ALA‐accredited Canadian library and information science (LIS) schools. The number of inlinks to the schools' web sites is used as an indicator of the visibility of all or some portions of the LIS web sites.

Inlinks pointing to the LIS school web sites were collected using the AlltheWeb search engine. The LIS school web pages pointed to by inlinks were manually analysed to discover visible topics and contents.

Four content clusters were identified by which to group the content of all the inlinked LIS school web pages. These clusters were LIS, research, home page and resources. The most visible cluster was the LIS cluster and the least visible was the research cluster. The most visible topics were student projects/activities, LIS‐related resources and course‐related information, in that order. The home page of each LIS school's web site was shown to be the single web page with the most visibility.

This was a comparative webometric study, which collected and analysed inlinks for seven Canadian LIS school web sites at two different times, 3 years apart (2003 and 2006). In the study, the ranking of visible clusters, topics and web pages from the LIS web sites were identified.