Search results

Legged robots are inevitably to interact with the environment while they are moving. This paper aims to properly handle these interactions. It works to actively control the joint torques of a hydraulic-actuated leg prototype and achieve compliant motion of the leg.

This work focuses on the modelling and controlling of a hydraulic-actuated robot leg prototype. First, the design and kinematics of the leg prototype is introduced. Then the linearlized model for the hydraulic actuator is built, and a model-based leg joint torque controller is presented. Furthermore, the virtual model controller is implemented on the prototype leg to achieve active compliance of the leg. Effectiveness of the controllers are validated through the experiments on the physical platform as well as the results from simulations.

The hydraulic joint torque controller presented in this paper shows good torque tracking performance. And the actively compliant leg successfully emulates the performance of virtual passive components under dynamic situations.

The main contribution of this paper is that it proposed a model-based active compliance controller for the hydraulic-actuated robot leg. It will be helpful for those robots that aim to achieve versatile and safe motions.

The purpose of this study is investigate the transient aerodynamic characteristics of high-speed vehicle with body roll motion under crosswind condition to improve aerodynamic stability.

An overset mesh was used to simulate the rolling motion of the vehicle body. A wind tunnel experiment was conducted to validate the numerical method.

The results revealed that the vehicle’s aerodynamic characteristics changed periodically with the body’s periodic motion. In the absence of crosswind, the pressure distribution on the left and right sides of the vehicle body was symmetrical, and the speed streamline flowed to the rear of the vehicle in an orderly manner. The maximum aerodynamic lift observed in the transient simulation was −0.089, which is approximately 0.70 times that of the quasi-static simulation experiment. In addition, the maximum aerodynamic side force observed in the transient simulation was 0.654, which is approximately 1.25 times that of the quasi-static simulation experiment.

The aerodynamic load varies periodically with the vehicle body’s cyclic motion. However, the extreme values of the aerodynamic load do not occur when the vehicle body is at its highest or lowest position. This phenomenon is primarily attributed to the mutual interference of airflow viscosity and the hysteresis effect in the flow field, leading to the formation of a substantial vortex near the wheel. Consequently, the aerodynamic coefficient at each horizontal position becomes inconsistent during the periodic rolling of the vehicle body.

This study aims to reconsider Chinese tourist gaze studies, examining the extent to which extant studies and theoretical models relating to the Chinese tourist gaze have overcome the Eurocentric limits of John Urry’s concept of the tourist gaze and elaborated the complexity of Chinese tourists’ gazes and visual practices.

Content analysis is carried out, examining research articles, books, book chapters and PhD and MSc theses collected from multiple English and Chinese databases.

The research results manifest that, overall, the previous studies, mobilise cultural essentialism, with an overestimation of the “Chineseness” of Chinese tourists’ behavioural patterns, which are widely believed to be framed by, but also constituting of, unique Chinese culture. Overdependence on Chinese cultural values and traditional philosophies as sources for rationale has resulted in a handful of theoretical frameworks, which appear to be of insufficient magnitude both in terms of their contribution to the original tourist gaze model and in their manifesting of the complexity of Chinese tourists’ visual behaviour. Indeed the divide that once deliberately set apart West and East, or more precisely Western and Chinese tourist gazes, seems to become accentuated in most attempts to study and write about Chinese tourist gaze(s). The previous studies thus largely serve to mirror the Eurocentrism of Urry’s gaze, rather than challenging it.

This study has a few limitations, especially, as this study only reviews and analyses the studies of the Chinese tourist gaze. It means that the conclusion might not well be generalised to either the investigation of the tourist gaze in another culture or the Chinese tourist studies, at large, which might exhibit a different pattern deserving more academic attention in future. Moreover, the authors recommend the future researchers, who are eager to probe Chinese tourists’ behavioural pattern, to seek for new pathways and alternative paradigms, which would be useful in overcoming the limits of cultural representations and in reducing the problematic Sino-Western divide.

Despite not aiming to reconceptualise the Chinese tourist gaze, this review paper contributes to the field of tourist gaze studies by engaging critically with the bias and theoretical insufficiencies that have emerged, while this concept is appropriated and re-formulated to explain Chinese tourists’ gazes and visual practices. On this basis, the authors suggest a critical redirection of the extant Chinese tourist gaze studies, which would be rather significant to those researchers in future with an interest to research what the Chinese tourists prefer to see in travel and how they engage with the gazee.

中国性与行为复杂性：反思中国游客凝视研究

本文重新检视有关中国游客凝视的研究, 审视现有研究和理论模型在多大程度上克服了约翰·厄里提出的游客凝视概念所蕴含的欧洲中心主义的局限, 并阐述中国游客凝视和视觉实践的复杂性。

本研究进行了内容分析; 资料来源于多个渠道的期刊论文、书籍、书章和博硕论文。

总体而言, 以往研究调动了文化本质主义, 过分强调了中国游客行为模式的“中国性”–被广泛认为受制于中国文化, 且也是中国文化一部分。对作为基本理论来源的中国文化价值观和传统哲学的过度依赖产生了一系列理论框架, 但它们在对最初的游客凝视模型的贡献上, 以及在对中国游客视觉行为的复杂性的阐释上, 都是不够的。在大部分中国游客凝视研究中, 以往对西方游客和中国游客的凝视的刻意区分都得以凸显, 从而映照出厄里的游客凝视概念所蕴含的欧洲中心主义。

虽然本评述论文并不致力于对中国游客凝视进行重新概念化, 但依旧对游客凝视研究领域做出了贡献。当游客凝视这一概念被挪用且重新定制以解释中国游客凝视和视觉实践时, 本文对涌现其间的偏见和理论上的缺陷进行了批判性的揭示。在此基础上, 我们认为, 有必要对有关中国游客凝视的研究做出批判性的重新定向。这对于未来有志于研究中国游客视觉偏好以及他们如何与被凝视者互动的研究人员而言, 尤其重要。

本研究有一些局限, 特别是, 因为我们只评价和分析了有关中国游客凝视的研究。这意味着, 我们的结论可能不能被推广至对其他文化情境下的游客凝视的调查, 也不能推广至中国游客研究整体。我们建议, 对中国游客行为模式感兴趣的研究人员需要寻求新的路径和替代性的范式, 以克服文化表象的局限并减少中西分歧带来的问题。

Carácter chino y la complejidad de comportamiento: repensar los estudios de la mirada del turista chino

Este artículo reconsidera los estudios de la mirada del turista chino para investigar hasta qué punto los estudios y los modelos teóricos existentes sobre la mirada del turista chino han superado los límites eurocéntricos del concepto de la mirada del turista de John Urry y explicado la complejidad de la mirada del turista chino y las prácticas visuales.

Se lleva a cabo el análisis de contenido investigando artículos de investigación, libros, capítulos de libros y las tesis de PhD y de MSc provenientes de las diversas bases de datos tanto en inglés como en chino.

Los resultados de la investigación manifiestan que, en general, los estudios anteriores movilizan el esencialismo cultural con una sobrestimación del “carácter chino” del modelo del comportamiento de turistas chinos, se cree en gran medida que el cual es motivado por la cultura china mientras forma parte de ella. Lo que la fuente de los fundamentos básicos sobredepende de los valores culturales y la filosofía tradicional de China resulta una pequeña cantidad de marcos teóricos, que no son suficientes tanto para la contribución al modelo original de la mirada del turismo como para manifestar la complejidad del comportamiento visual de turistas chinos. De hecho, se destaca la intención de la separación del Occidente y el Oriente, o hablando de forma precisa, de la mirada del turista occidental y la del turista chino al estudiar y escribir sobre la mirada del turista chino. Los estudios anteriores reflejan el eurocentrismo de la mirada de Urry en vez de ponerlo en duda.

A pesar de que el artículo no tiene la reconceptualización de la mirada del turista chino como su objetivo, contribuye al ámbito de la investigación de la mirada del turista a través de revelar de manera crítica el prejuicio y la insuficiencia teórica que ya ha existido cuando se usa y se reformula este concepto para explicar la mirada del turista chino y las prácticas visuales. Con lo que hemos mencionado, planteamos una redirección crítica de los estudios existentes de la mirada del turista chino, lo cual sería significativo para aquellos que tienen la intención de investigar qué prefieren ver los turistas chinos durante el viaje y cómo van a interactuar con los mirados en el futuro.

Esta investigación tiene varios límites, sobre todo, como solo revisamos y analizamos los estudios de la mirada del turista chino, lo cual significa que nuestra conclusión no se podría generalizar tanto a la investigación de la mirada del turista de otras culturas como a los estudios del turismo chino, que mostrarían un modelo diferente que merece más atención académica en el futuro. Al mismo tiempo, recomendamos a las personas que se interesen por investigar el modelo del comportamiento de los turistas chinos buscar nuevos caminos y paradigmas alternativos, los cuales serían útiles para superar los límites de las representaciones culturales y reducir la división problemática sino-occidental.

The purpose of this paper is to overcome the deficiency of the current GM(1,N) such as low‐prediction precision, extend the scope of GM(1,N) and provide an effective grey dynamic model GM(1,N) for the relationship of cost and variability.

The relationship between two factors of variety and the cost of manufacturing system is studied on the basis of the variety reduction program theory. Based on the Grey system and the gradient algorithm, a Grey dynamic model GM(1,N) is proposed between cost and variety by optimizing the coefficient and background value of the model which is used to check validity for the relation of plasm‐yarn machine product and variety.

The proposed Grey dynamic prediction model GM(1,N) for the relationship of cost and variability has high precision and easy‐to‐use.

A Grey model GM(1,N) for prediction is proposed.

The proposed model should also have potential for multifactor system prediction in engineering.

The deficiency of the current GM(1,N) is overcome, the scope of GM(1,N) is extended and the proposed Grey dynamic model GM(1,N) has high‐prediction precision.

During the forming process, aluminum alloy sheets develop various types of textures and are subjected to cyclic loading as structural components, resulting in fatigue damage. This study aims to develop polycrystalline models with different orientation distributions and incorporate suitable fatigue indicator parameters to investigate the effect of orientation distribution on the mechanical properties of Al-7.02Mg-1.78Zn alloys under cyclic loading.

In this study, a two-dimensional polycrystalline model with 150 equiaxed grains was constructed based on optical microscope images. Subsequently, six different orientation distributions were assigned to this model. The fatigue indicator parameter of strain energy dissipation is utilized to analyze the stress response and fatigue crack driving force in polycrystalline models with different orientation distributions subjected to cyclic loading.

The study found that orientation distribution significantly influences fatigue crack initiation. Orientation distributions with a larger average Schmid factor exhibit reduced stress response and lower fatigue indicator parameters. Locations with a larger average Schmid factor experience greater plastic deformation and present a higher risk for fatigue crack initiation. RVE with a single orientation undergoes more rotation to reach cyclic steady state under cyclic loading due to the ease of deformation transfer.

Currently, there are no reports in the literature on the calculation of fatigue crack initiation for Al-Mg-Zn alloys using the crystal plasticity finite element method. This study presents a novel strategy for simulating the response of Al-7.02Mg-1.78Zn materials with different orientation distributions under symmetric strain cyclic loading, providing valuable references for future research.

This paper aims to investigate the thermal oxidation characteristics of the unsaturated bonds (C=C) of trimethylolpropane trioleate (TMPTO) and to reveal the high temperature oxidation decay mechanism of unsaturated esters and the nature of the anti-oxidation properties of the additives.

Using a DXR laser microscopic Raman spectrometer and Linkam FTIR600 temperature control platform, the isothermal oxidation experiments of TMPTO with or without 1.0 wt. % of different antioxidants were performed.

The results indicated that the Raman peaks of =C-H, C=C and -CH₂- weaken gradually with prolonged oxidation time, and the corresponding Raman intensities drop rapidly at higher temperatures. The aromatic amine antioxidant can decrease the attenuation of peak intensity, as it significantly reduces the rate constant of C=C thermal oxidation. The hindered phenolic antioxidant has a protective effect during the early stages of oxidation (induction period), but it may accelerate the oxidation of C=C afterwards.

Research on the structure changes of synthetic esters during oxidation by Raman spectroscopy will be of great importance in promoting the use of Raman spectroscopy to analyze the oxidation of lubricants.

The purpose of this paper is to investigate the effect of the soft annealing time on the microstructure and hydrogen embrittlement (HE) of Fe-0.22C-11.54Mn-2.05Al steels.

Steels A and B with different morphologies were prepared by cold rolling after warm rolling, long/short softening annealing and finally annealing at 700 °C for 30 min. Uncharged and charged samples were subjected to tensile, and HE behavior was studied by electron backscattered diffraction, scanning electron microscopy and X-ray diffraction.

The two samples exhibited similar tensile strengths. The homogeneous equiaxed microstructure of steel B was found to be more conducive to relieve its HE sensitivity. Steel A exhibited bimodal-grained microstructures – blocky and lath. The formation of crack in the blocky grains of steel A resulted in a significant reduction in its plasticity and tensile strength.

The high HE susceptibility of steel A is mainly connected with the inhomogeneity of martensite transformation.

The purpose of this paper is to develop a two-way coupling approach for investigating the aerodynamic stability of vehicles under the combined effect of crosswind and road adhesion.

The author develops a new two-way coupling approach, which couples large eddy simulation with multi-body dynamics (MBD), to investigate the crosswind stability on three different adhesion roads: ideal road, dry road and wet road. The comparison of the results obtained using the traditional one-way coupling approach and the new two-way coupling approach is also done to assess the necessity to use the proposed coupling technique on low adhesion roads, and the combined effect of crosswind and road adhesion on vehicle stability is analyzed.

The results suggest that the lower the road adhesion is, the larger deviation a vehicle generates, the more necessary to conduct the two-way coupling simulation. The combined effect of the crosswind and road adhesion can decrease a vehicle’s lateral motion on a high adhesion road after the disappearing of the crosswind. But on a low adhesion road, the vehicle tends to be unstable for its large head wind angle. The vehicle stability in crosswind on a low adhesion road needs more attention, and the investigation should consider the coupling of aerodynamics and vehicle dynamics and the combined effect of crosswind and road adhesion.

Developing a new two-way coupling approach which can capture the complex vehicle structures and the road adhesion with MBD model and the completed fluid filed structure with CFD model. The present study might be the first study considering the coupling of crosswind and low adhesion road. The proposed two-way coupling approach will be useful for researchers who study vehicle crosswind stability.

How to successfully drive open innovation (OI) has become an important issue. However, the existing literature on the determinants of OI focuses on organizational and situational factors, while the “human side” of it remains poorly understood. To address such problem, this paper examines the impact of two core qualities of CEOs – CEO power and social capital – on three representative OI modes from a micro-level perspective.

This paper uses the data of 4,213 firm-year observations from Chinese A-share listed companies. A panel logit model is used to test the hypotheses, and the author also uses clustering robust standard errors to ensure the robustness of the model.

A powerful CEO can drive the firm's adoption of technology, organization and market-oriented OI, and different types of social capital have a differential impact on such relationship. Specifically, the CEO's political social capital has a negative moderating effect, while his/her stronger business social capital can enhance the positive relationship between CEO power and various types of OI activities, as well as mitigate the negative effect of political social capital.

This paper echoes the call for more attention to be paid to the microfoundations of OI and provides theoretical implications for research on the convergence of OI and strategic leadership.

This paper analysed survey data of 715 rice-producing households in China to assess the determinants of adoption of five mutually exclusive soil conservation practices (SCPs) and their impact on rice yield and chemical fertiliser use.

The multinomial endogenous treatment effects model was used to account for selection bias and endogeneity arising from both observed and unobserved heterogeneity.

Farms that adopted SCPs as a package experienced an increase in rice yield and decrease in chemical fertiliser use. Adoption of SCPs as a package led to a 12.0% increase in yield and 15.2% decrease in chemical fertiliser use; these results have policy implications for the non-point source pollution control in the agricultural sector. In contrast, adoption of straw retention only significantly reduced yield by 4.9% and increased chemical fertiliser use by 18.1%.

The authors evaluate and compare multi-type of SCPs, such as straw retention, deep tillage and use of organic fertiliser, separately or in combination, and their impacts on smallholder farmers’ rice yield and chemical fertiliser usage.