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Six-axis force sensors play an important role in civilian and military fields because of their multifunctionality. In the context of sensor structure design, sensitivity and sensitivity isotropy are often considered. This paper aims to study the possible relationship between the sensitivity/sensitivity isotropy and structural parameters of an 8/4–4 parallel six-axis force sensor. A comprehensive evaluation index and structural optimization design scheme are suggested in the end.

Based on the conditional number of the Jacobian matrix spectral norm, the sensitivity and sensitivity isotropy of the sensor are derived. Orthogonal experiments are used to determine the degree of primary and secondary factors that have a substantial effect on the sensor characteristics. The relationship between the performance indices and the structural parameters is analyzed by the performance atlas method. The comprehensive evaluation index lays the foundation for the structural optimization design of an 8/4–4 parallel six-axis force sensor.

The variation in each performance index of the sensor for each of the structural parameters is analyzed, and the structural parameters of the sensor with the desired performance indices can be easily selected from the performance atlases. A comprehensive performance evaluation index with a target value of 1 is proposed, and the overall influence of the structural parameters on the sensor performance index is investigated. A simulation example shows the feasibility of the proposed evaluation index.

The importance of each structural parameter of the 8/4–4 parallel six-axis force sensor is determined through orthogonal experiments in this paper. Relations among the structural parameters meeting the performance indices are derived and shown in the performance atlases. A comprehensive evaluation index is proposed to analyze the overall sensor performance.

Over the past several decades, there has been an increasing trend towards inter-city cooperation, which is an efficient policy option to deal with the challenges from globalization, regionalization and the externalities resulting from urban entrepreneurialism. Specific to China, the city governments, which mainly refer to prefecture-level and county-level governments, have also made many attempts to cooperate with respect to their local economic development and public affairs. Nevertheless, the results of these initiations to cooperate vary to a great extent. Based on a review of regional pollution governance in the Xiaoqing River area, tourism cooperation initiatives at Weishan Lake and transport integration between Jinan and Laiwu. The findings demonstrate that China's idiosyncratic institutional background has a significant impact on the shaping of inter-city cooperation. For the most part, leading small groups (LSGs) and their leadership property tend to determine the effectiveness of inter-city cooperation.

To examine the effect of the LSGs, we categorize them into three types, groups with strong leadership, weak leadership and self-forming leadership. Through reviewing regional pollution governance in the Xiaoqing River area, tourism cooperation initiatives at Weishan Lake and transport integration between Jinan and Laiwu, we try to probe the role of leading groups in the settlement of cross-administrative border issues.

Based on these three cases, the conclusion can be drawn that the leadership type of the LSG can exert an important influence on the efficiency of inter-city cooperation. If there is a leader with a higher administrative rank or authority, the cooperation can be quite efficient. Otherwise, the cooperative ending might be very negative. In terms of the operation principle, we can infer that even though the cities are always self-development oriented, the leader with higher authority or a strong coordinating capacity can convince and persuade the city leaders to overcome their self-centered behavior template and boost the cooperation to March on smoothly. Also, it means that the LSG is constrained by its personalistic characteristic. Key command derives from the person who chairs the LSG other than specific rules and norms. If the lead of the LSG leaves his position, the cooperation might just become paralyzed. From this point of view, the lack of legal basis remains to be the LSGs' significant deficiency and the future reform should attach more importance to the legalization of the LSGs so the operation of LSGs can be more standard and stable.

Many scholars have proposed their own theoretical models to explain the reason some cities successfully and effectively form cooperative relations, while the other cities do not. However, their models do not consider the idiosyncratic context of China or, how and to which extent LSGs can promote cooperation. Therefore, this paper seeks to probe which path in the context of China cities usually follows in the formation of joint efforts, and what role LSGs play in enabling cities to cooperate.

This paper aims to research the tribological and dynamic characteristics of aeroengine hybrid ceramic bearings through wear experiments and simulation analysis.

First, the authors carried out wear experiments on Si₃N₄–GCr15 and GCr15–GCr15 friction pairs through the ball-disc wear test rig to explore the tribological properties of their materials. Second, using ANSYS/LS-DYNA simulation software, the dynamic simulation analysis of hybrid bearings was carried out under certain working conditions, and the dynamic contact stress of all-steel bearings of the same size was simulated and compared. Finally, the change of the maximum contact stress of the main bearing under the change of load and rotation speed was studied.

The results show that the Si₃N₄–GCr15 pair has better tribological performance. At the same time, under the conditions of high speed and heavy load, the simulation analysis shows that the contact stress between the ceramic ball and the raceway of the ring is smaller than the steel ball. That is, hybrid bearings have better transient mechanical properties than all-steel bearings. With the speed increasing to 12,000 r/min, the maximum stress point will shift in the inner and outer rings.

In this study, the tribological and transient mechanical properties of Si₃N₄ material were comprehensively analyzed through wear experiments and dynamic simulation analysis, which provided a reference for the design of hybrid bearings for next-generation aeroengines.

This study aims to further study the fire resistance of prefabricated concrete beam-column joints with end-plate connection. This paper aims to analyze the fire resistance of this joint in prefabricated reinforced concrete frame structure (PRCS).

First, the accuracy of the model is verified by using the test data. Based on this, a refined finite element model of PRCS structure with two stories and two spans is established. The influence of four working conditions with different fire floors (positions) and different axial compression ratios on the deformation, failure and fire resistance of PRCS structure are analyzed.

The results show that under the four working conditions, the fire resistance of the PRCS structure under Condition 1 and Condition 2 is smaller. It shows that the beam deformation develops slowly in PRCS structure under four kinds of fire positions, and the large displacement emerges 60 min later, which is poles apart from that of prefabricated beam column members. With the increase of the fire time, the material is damaged and deteriorated, which leads to the eccentricity of the axial load, so that the column top appears large lateral displacement. Under the Conditions 1 and 3, the lateral displacement of the column gradually decreases as the axial compression ratio rises.

It is found that there is a distinct lack of researching on the fire resistance of prefabricated joints, and the existed research studies are limited to the fire resistance of members. Thus, it is necessary to strengthen the first floor and side column design of prefabricated frame structure.

The purpose of this paper is to solve the problem that the relationship between loading forces, which were applied at different positions on a plane, and output values of load-sharing dynamometer is non-linear.

First, the analytical model of ISPM (isodynamic surface proportional mapping method) method, which is used to calibrate dynamometer, was established. Then, a series of axial force calibration tests were performed on a load-sharing dynamometer at different loading positions. Finally, according to output values, calibration forces at different loading positions were calculated by ISPM method, and corresponding distribution histogram of calibration force error was generated.

The largest error between calculated force and standard force is 2.92 per cent, and the probability of calculated force error within 1 per cent is 91.03 per cent, which verify that the ISPM method is reliable for non-linear calibration of dynamometers.

The proposed ISPM method can achieve non-linear calibration between measured force and output signal of load-sharing dynamometer at different positions. In addition, ISPM method can also solve some complex non-linear problems, such as prediction of plane cutting force under the influence of multiple parameters, the force measurement of multi-degree-of-freedom platform and so on.