Search results

In order to optimize SCSWIRC, the simplification and further optimization method is proposed. SCSWIRC's optimization includes two levels. The first level refers to simplifying structural system from the perspective of components; the second level refers to optimizing components' sectional areas from the perspective of mechanics. The first level aims to remove redundant components, and the second level aims to reduce structural self-weight based on the first level. The purpose of the paper is to simplify SCSWIRC's structural system and optimize structural self-weight and reduce construction forming difficulty.

Grid-jumping layout and multi-objective optimization method is used to simplify and further optimize Spatial cable-truss structure without inner ring cables (SCSWIRC). Grid-jumping layout is used to simplify remove redundant components, and multi-objective optimization method is used to reduce structural self-weight. The detailed solving process is given based on grid-jumping layout and multi-objective optimization method.

Take SCSWIRC with a span of 100m as an example to verify the feasibility and correctness of the simplification and further optimization method. The optimization results show that 12 redundant components are removed and the self-weight reduces by 3.128t from original scheme to grid-jumping layout scheme 1. The self-weight reduces from 36.007t to 28.231t and feasible coefficient decreases from 1.0 to 0.627 from grid-jumping layout scheme 1 to multi-objective optimization scheme. The simplification and further optimization can not only remove the redundant components and simplify structural system to reduce construction forming difficulty, but also optimize structural self-weight under considering structural stiffness to reduce project costs.

The proposed method firstly simplifies SCSWIRC and then optimizes the simplified SCSWIRC, which can solve the optimization problem from the perspective of components and mechanics. Meanwhile, the optimal section solving method can be used to obtain circular steel tube size with the optimal stiffness of the same areas. The proposed method successfully solves the problem of construction forming and project cost, which promotes the application of SCSWIRC in practical engineering.

The purpose of this paper is to propose a novel jump control method based on Two Mass Spring Damp Inverted Pendulum (TMS-DIP) model, which makes the third generation of hydraulic driven wheel-legged robot prototype (WLR-3P) achieve stable jumping.

First, according to the configuration of the WLR, a TMS-DIP model is proposed to simplify the dynamic model of the robot. Then the jumping process is divided into four stages: thrust, ascent, descent and compression, and each stage is modeled and solved independently based on TMS-DIP model. Through WLR-3P kinematics, the trajectory of the upper and lower centroids of the TMS-DIP model can be mapped to the joint space of the robot. The corresponding control strategies are proposed for jumping height, landing buffer, jumping attitude and robotic balance, so as to realize the stable jump control of the WLR.

The TMS-DIP model proposed in this paper can simplify the WLR dynamic model and provide a simple and effective tool for the jumping trajectory planning of the robot. The proposed approach is suitable for hydraulic WLR jumping control. The performance of the proposed wheel-legged jump method was verified by experiments on WLR-3P.

This work provides an effective model (TMS-DIP) for the jump control of WLR-3P. The results showed that the number of landing shock (twice) and the pitch angle fluctuation range (0.44 rad) of center of mass of the jump control method based on TMS-DIP model are smaller than those based on spring-loaded inverted pendulum model. Therefore, the TMS-DIP model makes the jumping process of WLR more stable and gentler.

Jumping robots with coordinated multiple legs have been a hot research subject during the past years because of their excellent abilities in fast moving and obstacle-climbing. However, dynamics of jumping process of these coordinated legged robots are complex because of collisions between coordinated legs and the ground. This paper aims to analyze features of jumping process and to present the kinematic and dynamic models of a novel sole-type quadruped jumping robot with variable coordinated joints.

A complete jumping period of is divided into several subphases according to contact status of different coordinated legs to the ground. Continuous dynamics and discrete dynamics are established in different subphases. Simulations are performed in MATLAB software and ADAMS environment.

Comparison between two-set simulated results acquired from ADAMS and MATLAB demonstrates the validity of kinematic and dynamic equations.

The established dynamics establish the foundation of further research in motion planning and controller design of coordinated multiple legs.

The purpose of this paper is to consider that the model of volatility characteristics is more reasonable and the description of volatility is more explanatory.

This paper analyzes the basic characteristics of market yield volatility based on the five-minute trading data of the Chinese CSI300 stock index futures from 2012 to 2017 by Hurst index and GPH test, A-J and J-O Jumping test and Realized-EGARCH model, respectively. The results show that the yield fluctuation rate of CSI300 stock index futures market has obvious non-linear characteristics including long memory, jumpy and asymmetry.

This paper finds that the LHAR-RV-CJ model has a better prediction effect on the volatility of CSI300 stock index futures. The research shows that CSI300 stock index futures market is heterogeneous, means that long-term investors are focused on long-term market fluctuations rather than short-term fluctuations; the influence of the short-term jumping component on the market volatility is limited, and the long jump has a greater negative influence on market fluctuation; the negative impact of long-period yield is limited to short-term market fluctuation, while, with the period extending, the negative influence of long-period impact is gradually increased.

This paper has research limitations in variable measurement and data selection.

This study is based on the high-frequency data or the application number of financial modeling analysis, especially in the study of asset price volatility. It makes full use of all kinds of information contained in high-frequency data, compared to low-frequency data such as day, weekly or monthly data. High-frequency data can be more accurate, better guide financial asset pricing and risk management, and result in effective configuration.

The existing research on the futures market volatility of high frequency data, mainly focus on single feature analysis, and the comprehensive comparative analysis on the volatility characteristics of study is less, at the same time in setting up the model for the forecast of volatility, based on the model research on the basic characteristics is less, so the construction of a model is relatively subjective, in this paper, considering the fluctuation characteristics of the model is more reasonable, characterization of volatility will also be more explanatory power. The difference between this paper and the existing literature lies in that this paper establishes a prediction model based on the basic characteristics of market return volatility, and conducts a description and prediction study on volatility.

The purpose of this paper is to develop a renewed understanding of social influence in the military by exploring officers' decision‐making processes in a stressful situation. The intention is to develop self‐awareness as a central leadership capability in authentic leadership.

During wintertime in Norway, standing half‐naked and blindfolded on a wharf, officer cadets were offered the choice of jumping or not jumping into the icy ocean. From that starting point, a qualitative dialogue evolved in which the cadets reflected on their decision‐making processes and explored their reasons for making their decision. Finally, the decision was executed by the cadets on whether to jump into the icy water or not.

The results from “the water jump” showed that most of the cadets jumped, indicating that they preferred physical inconvenience over social inconvenience, and that officers are highly influenced by their group and the military organization.

The research was conducted with a relatively small group and the findings may not generalize readily to other populations.

The “water jump” has been adopted by the Royal Norwegian Navy, and is under consideration by the Army and Police in Norway. Using the physical environment as a background to tap into the cadets' thinking in action provides knowledge about the individual self and social influence relevant to growth as leaders.

The paper is one of few to explore the role of social influence in the context of a military real‐world leadership training activity. Moreover, addressing social influence as a potential drawback in decision making is done to enhance self‐awareness as a central leadership capability of authentic leaders in operations.

The purpose of this paper is to present a new scout robot that tries to combine the hopping movement and the wheeling movement to greatly enlarge the scope of robot's activities.

A five‐shank hopping mechanism was employed to build the wheeling‐hopping combination scout robot. The non‐linear character of the five‐shank hopping mechanism was analyzed and then used in the proposed non‐linear spring‐mass model for the robot.

The rules of robot's movement were deduced, influencing factors of the jumping height were analyzed and the countermeasure was adopted. Simulations and an experiment of the robot's movement showed that the robot has strong locomotivity and survival ability.

A five‐shank hopping mechanism is proposed, analyzed and combined with wheeling movement to enhance the locomotivity and survival ability of scout robot.

This paper seeks to explore whether the global market segment Generation Y shares a common perception of a specific consumption activity, namely bungy jumping, and how perceptions of cool operate around that.

A qualitative methodology is adopted, appropriate to the exploratory aims of the research, which utilises existing filmed interviews to elicit responses from other members of Generation Y. The research explores shared identification, meaning and knowledge of a specific consumption practice, namely commercial bungy jumping.

The actual form of consumption, bungy jumping was widely accepted as being “cool” but a global consensus on a “cool” consumer and their story could not be reached. The research concludes by proposing a hierarchy for the attribution of cool from one Generation Y member to another; thus extending theoretical discussion and knowledge by investigating an established concept in a specific context to illustrate the complex and uneven nature of cultural globalisation.

This research interprets global Generation Y culture from a small convenience sample from America, Ireland, Scotland and England, thus generating avenues for further research as discussed.

These findings have value for businesses that create consumption experiences for Generation Y customers and scholars seeking insight into the plural and complex function of cool.

The purpose of this paper is to explore the effects of low doses of caffeine (<3 mg/kg) on jumping performance using a meta-analysis.

The search for eligible studies was performed through six databases, with additional backward and forward citation tracking. A random-effects meta-analysis was performed to compare the effects of caffeine vs placebo on jump height. The methodological quality of the included studies was appraised using the physiotherapy evidence database checklist.

Eight studies were included in the review. They were classified as good or excellent methodological quality. The pooled number of participants across all studies was 203. Four studies provided caffeine in relative doses, ranging from 1 to 2 mg/kg. Four studies provided caffeine supplementation in absolute doses of 80, 150 or 200 mg. The meta-analysis found that caffeine ingestion increased vertical jump height (Cohen’s d: 0.21; 95% confidence interval: 0.10, 0.31; p < 0.001; +3.5%).

The present meta-analysis found that caffeine doses of ∼1 to 2 mg/kg enhance jumping height. The effects observed herein are similar to those with higher caffeine doses, which is relevant as low caffeine doses produce minimal side effects. For most individuals, a caffeine dose of ∼1 to 2 mg/kg is equivalent to an amount of caffeine in an energy drink, one to two cups of coffee, one to two pieces of caffeinated chewing gum or several cups of green tea.

For most practical control system problems, the state variables of a system are not often available or measureable due to technical or economical constraints. In these cases, an observer-based controller design problem, which is involved with using the available information on inputs and outputs to reconstruct the unmeasured states, is desirable, and it has been wide investigated in many practical applications. However, the investigation on a discrete-time singular Markovian jumping system is few so far. This paper aims to consider an observer-based control problem for a discrete-time singular Markovian jumping system and provides a set of easy-used conditions to the proposed control law.

According to the connotation of the separation principle extended from linear systems, a mode-dependent observer and a state-feedback controller is designed and carried out independently via two sets of derived necessary and sufficient conditions in terms of linear matrix inequalities (LMIs).

A set of necessary and sufficient conditions for an admissibility analysis problem related to a discrete-time singular Markovian jumping system is derived to be a doctrinal foundation for the proposed design problems. A mode-dependent observer and a controller for such systems could be designed via two sets of strictly LMI-based synthesis conditions.

The proposed method can be applied to discrete-time singular Markovian jumping systems with transition probability p_ij > 0 rather than the ones with p_ii = 0.

The formulated problem and proposed methods have extensive applications in various fields such as power systems, electrical circuits, robot systems, chemical systems, networked control systems and interconnected large-scale systems. Take robotic networked control systems for example. It is recognized that the variance phenomena derived from network transmission, such as packets dropout, loss and disorder, are suitable for modeling as a system with Markovian jumping modes, while the dynamics of the robot systems can be described by singular systems. In addition, the packets dropout or loss might result in unreliable transmission signals which motivates an observer-based control problem.

Both of the resultant conditions of analysis and synthesis problems for a discrete-time singular Markovian jumping system are necessary and sufficient, and are formed in strict LMIs, which can be used and implemented easily via MATLAB toolbox.

Spherical robot plays an essential role in the field of mobile robot because of its unique shape and omni-directional mobility, especially in the application of planet detection. Although spherical robot has many advantages over leg robot, its obstacle climbing performance is still not satisfactory, that is exactly the motivation of this paper. The purpose of this paper is to propose a high-performance hopping mechanism for spherical robot, which can adapt to different terrain and effectively cross obstacles.

The hopping system uses torque spring as part of the energy storage mechanism, and converts the kinetic energy of rotation into elastic potential energy with a particularly designed turntable. Moreover, the track of the turntable, based on the Archimedes spiral principle, has the attributes of equidistance and equivelocity that enable better stability of energy storage process.

Experiments show that the proposed hopping mechanism can make a 250 g spherical robot jump up to 58 cm with the take-off angle of 60°. Finally, the influence of friction and take-off angle on the hopping height and distance of the robot is also analyzed, which provides a prior guidance for optimizing its jumping process.

This paper shows how to easily design a lightweight, compact and embedded spring hopping structure so that a spherical hopping robot with detection ability can be developed.