Search results

The purpose of this paper is to propose a decentralized output feedback controller for cooperative attitude regulation of spacecraft formation in absence of angular velocity feedback.

The nonlinear relative attitude dynamic and kinematic equations represented by relative quaternion and relative angular velocity, respectively, are considered in this paper. The lead filter is employed to synthesize virtual angular velocity signal so that the design of output feedback controller is achieved. Lyapunov method is adopted to prove the stability of closed‐loop system. Considering the external disturbance, the theory of L2‐gain disturbance attenuation is employed to improve the designed controller. Numerical simulations are carried out to verify the controllers proposed.

It is found that the closed‐loop system can be guaranteed asymptotically stable in absence of external disturbance. When disturbance is considered, as long as the sufficient condition proposed is satisfied, the improved controller can render system uniformly ultimately bounded stable.

The proposed output feedback control scheme can be considered as a fall‐back alternative for the case that the angular velocity sensors fail, or seen as another option for the system without angular velocity sensors at all.

Unlike most classical works in the field of output feedback which focus on centralized scheme and neglect the disturbance, the controller proposed in this paper is able to handle the output feedback control problem of multi‐agent formation in a decentralized fashion, so as to avoid the single failure point of a centralized scheme. Meanwhile, the capability of L2‐gain disturbance attenuation is also achieved simultaneously.

In this paper, my claim is that employee ownership of industrial companies enables economic survival, democracy, and joint responsibility. My main focus is a case study of Ljuders Nickelsilfverfabrik and its change to employee ownership. In 1980, 36 of the 42 employees became owners. My research question is how have the economy and democracy in an employee-owned industrial company changed over the years? My main research method includes a 35-year in-depth longitudinal case study of Ljuders Nickelsilfverfabrik since its employee takeover. The empirical material includes documents, interviews, participant observations, and informal talks over the entire study period. My theory is based on the study by Connell Fanning and McCarthy (1983, 1986), who have compiled the critical literature on employee-owned companies and have asked why so few employee-owned companies exist in Western economies. They formulate six non-viability hypotheses for employee ownership, against which I present my empirical study and conclude that employee ownership is possible. From my case study in combination with the literature about organizational changes, I formulate a recipe for a successful employee takeover and collective entrepreneurship. The experience of Ljuders Nickelsilfverfabrik shows that a more complete business idea can subsequently unfold with the help of different people’s knowledge and experiences. Degeneration from democratic to more traditional ownership and control can be avoided by placing new people in leadership positions. The management must create legitimacy for a different organizational form for internal and external stakeholders.

The purpose of this paper is to investigate the factors that influence police officers’ tendency to cooperate with private investigators.

A questionnaire survey method was used on a sample of 377 police officers in South Korea.

The findings suggested that, unlike previous literature, police officers’ rational choice (cost vs benefit calculation) was the most important factor, and characteristics of cases also significantly influenced police officers’ tendency to work with private investigators. Also, officers’ job assignment was relevant, unlike the organizational cultural context for cooperation.

Prior studies have continuously emphasized the importance of cooperation between public police and private police (particularly private investigators) in order to enhance effectiveness in crime fighting and the preventive functions of policing. However, the studies have not produced empirical evidence as to how cooperation between the two sectors could be enhanced. This study fills this void in the literature.

Smallholder farmers are increasingly subject to different types of standards that offer specific conditions for their market incorporation. The proliferation of private and voluntary (civic) standards raises questions regarding their impact on farmers' welfare and their role in the upgrading of value chains. This paper aims to address this issue.

Based on extensive fieldwork and careful matching of 315 farmers in Northern Nicaragua who produce coffee under Fair Trade, Rainforest Alliance and Café Practices labels or deliver to independent traders, the effects on income, production and investments are compared. Moreover, the implications of different contract conditions for risk behaviour, organizational force, loyalty and gender attitudes are assessed.

The paper finds that Fair Trade provides better prices compared with independent producers, but private labels out‐compete Fair Trade in terms of yield and quality performance. While Fair Trade can be helpful to support initial market incorporation, private labels offer more suitable incentives for quality upgrading.

Civic standards exhibit major effects on local institutions' and farmers' behaviour, while B2B standards are more effective for improving production and management practices. Dynamic improvement standards may bridge the gap between both.

Fair Trade standards are useful to provide initial market access to small‐holders, but private standards offer better prospects for subsequent quality upgrading.

This is the first large‐scale comparative impact assessment of coffee standards that delivers unbiased empirical results.

Using Brandenburger and Nalebuff's 1995 co‐opetition model as a reference, the purpose of this paper is to seek to develop a tool that, based on the tenets of classical game theory, would enable scholars and managers to identify which games may be played in response to the different conflict of interest situations faced by companies in their business environments.

The literature on game theory and business strategy are reviewed and a conceptual model, the strategic games matrix (SGM), is developed. Two novel games are described and modeled.

The co‐opetition model is not sufficient to realistically represent most of the conflict of interest situations faced by companies. It seeks to address this problem through development of the SGM, which expands upon Brandenburger and Nalebuff's model by providing a broader perspective, through incorporation of an additional dimension (power ratio between players) and three novel, respectively, (rival, individualistic, and associative).

This proposed model, based on the concepts of game theory, should be used to train decision‐ and policy‐makers to better understand, interpret and formulate conflict management strategies.

A practical and original tool to use game models in conflict of interest situations is generated. Basic classical games, such as Nash, Stackelberg, Pareto, and Minimax, are mapped on the SGM to suggest in which situations they could be useful. Two innovative games are described to fit four different types of conflict situations that so far have no corresponding game in the literature. A test application of the SGM to a classic Intel Corporation strategic management case, in the complex personal computer industry, shows that the proposed method is able to describe, to interpret, to analyze, and to prescribe optimal competitive and/or cooperative strategies for each conflict of interest situation.

The purpose of this paper is to investigate the attitude cooperation control of multi-spacecraft with in-continuous communication.

A decentralized state-irrelevant event-triggered control policy is proposed to reduce control updating frequency and further achieve in-continuous communication by introducing a self-triggered mechanism.

Each spacecraft transmits data independently, without the requirement for the whole system to communicate simultaneously. The local predictions and self-triggered mechanism avoid continuous monitoring of the triggering condition.

This investigation is suitable for small Euler angle conditions.

The control policy based on event-triggered communication can provide potential solutions for saving communication resources.

This investigation uses event- and self-triggered policy to achieve in-communication for the multi-spacecraft system.

This paper aims to investigate the fast attitude coordinated control problem for rigid satellite swarms with communication delays.

Based on behavior‐based control approach, the attitude control system is designed to guarantee that the attitude of the satellite swarm converge to a dynamic reference state in finite time. A fast sliding mode is developed to improve the convergence rate and robustness of the control system. All the effects of communication delays, parameter uncertainties and external disturbances are taken into account simultaneously, and the communication topology of the satellite swarm can be arbitrary types. Numerical simulations are provided to demonstrate the analytic results.

Despite the existence of communication delays, parameter uncertainties and external disturbances, the stability of the closed‐loop system can be successfully guaranteed and the proposed control strategies are effective to overcome these unexpected phenomena subject to arbitrary communication topology.

This paper introduces a fast terminal sliding mode control method which can guarantee the fast convergence of the attitude state of the satellite swarm in the presence of communication delays, switched communication topology, parameter uncertainties and external disturbances.

Today's supply chains face increasing vulnerabilities; effective management of disruptions is critical to an organization's ability to weather disruptive events and remain competitive. Contingency planning is a method of risk management that promotes effective crisis management. This research tests proposed antecedents of contingency planning effectiveness in a supply chain setting.

A survey method was used to gather data from 103 participants who are involved in their respective organization's contingency planning and implementation processes. The data were analyzed using partial least squares to examine relationships between contingency planning effectiveness, inter‐organizational information technology (IT) use, cooperative attitude, and inter‐organizational collaboration.

The proposed model explains 87 percent of the variance in contingency planning effectiveness. The findings suggest that inter‐organizational collaboration, inter‐organizational IT use, and cooperative attitude directly impact contingency planning effectiveness. Inter‐organizational collaboration mediates the relationships between the other antecedents and contingency planning effectiveness.

Although effective contingency planning has been shown to influence positive outcomes, the relationship between contingency planning effectiveness and its antecedents is not well understood in extant literature. This study identifies and investigates key antecedents to contingency planning effectiveness and provides a foundation for continued investigation.

Substantial changes in the education system and the shift to online classes during the lockdown have raised teachers’ attention to the idea of practicing cooperative learning in online environments. Cooperative learning activities enhance academic skills if designed effectively. This study aims to explore students’ attitudes toward cooperative learning in online learning environments.

This study is a descriptive study. A survey was administered to 50 graduate and postgraduate students of English as a Foreign Language.

Results indicated that the students had positive attitudes toward the integration of cooperative tasks in online environments. They also revealed no significant differences in the attitudes toward cooperative learning based on the students’ level (i.e. undergraduate or postgraduate) and that the students preferred small groups.

Cooperative learning is a widely researched topic, especially in higher education. However, most of the previous studies reported results of the implementation of cooperative learning in traditional classrooms. This study aimed to fill this gap by examining the impact of online tools on cooperative learning.