Search results

In recent years, owing to the rapidly increasing labor costs, the demand for robots in daily services and industrial operations has been increased significantly. For further applications and human–robot interaction in an unstructured open environment, fast and accurate tracking and strong disturbance rejection ability are required. However, utilizing a conventional controller can make it difficult for the robot to meet these demands, and when a robot is required to perform at a high-speed and large range of motion, conventional controllers may not perform effectively or even lead to the instability.

The main idea is to develop the control law by combining the SMC feedback with the ADRC control architecture to improve the robustness and control quality of a conventional SMC controller. The problem is formulated and solved in the framework of ADRC. For better estimation and control performance, a generalized proportional integral observer (GPIO) technique is employed to estimate and compensate for unmodeled dynamics and other unknown time-varying disturbances. And benefiting from the usage of GPIO, a new SMC law can be designed by synthesizing the estimation and its history.

The employed methodology introduced a significant improvement in handling the uncertainties of the system parameters without compromising the nominal system control quality and intuitiveness of the conventional ADRC design. First, the proposed method combines the advantages of the ADRC and SMC method, which achieved the best tracking performance among these controllers. Second, the proposed controller is sufficiently robust to various disturbances and results in smaller tracking errors. Third, the proposed control method is insensitive to control parameters which indicates a good application potential.

High-performance robot tracking control is the basis for further robot applications in open environments and human–robot interfaces, which require high tracking accuracy and strong disturbance rejection. However, both the varied dynamics of the system and rapidly changing nonlinear coupling characteristic significantly increase the control difficulty. The proposed method gives a new replacement of PID controller in robot systems, which does not require an accurate dynamic system model, is insensitive to control parameters and can perform promisingly for response rapidity and steady-state accuracy, as well as in the presence of strong unknown disturbances.

This study aims to propose an adaptive fractional-order sliding mode controller to solve the problem of train speed tracking control and position interval control under disturbance environment in moving block system, so as to improve the tracking efficiency and collision avoidance performance.

The mathematical model of information interaction between trains is established based on algebraic graph theory, so that the train can obtain the state information of adjacent trains, and then realize the distributed cooperative control of each train. In the controller design, the sliding mode control and fractional calculus are combined to avoid the discontinuous switching phenomenon, so as to suppress the chattering of sliding mode control, and a parameter adaptive law is constructed to approximate the time-varying operating resistance coefficient.

The simulation results show that compared with proportional integral derivative (PID) control and ordinary sliding mode control, the control accuracy of the proposed algorithm in terms of speed is, respectively, improved by 25% and 75%. The error frequency and fluctuation range of the proposed algorithm are reduced in the position error control, the error value tends to 0, and the operation trend tends to be consistent. Therefore, the control method can improve the control accuracy of the system and prove that it has strong immunity.

The algorithm can reduce the influence of external interference in the actual operating environment, realize efficient and stable tracking of trains, and ensure the safety of train control.

Small highly saturated interior permanent magnet- synchronous machines (IPMSMs) show a very nonlinear behaviour. Such machines are mostly controlled with a closed-loop cascade control, which is based on a d-q two-axis dynamic model with constant concentrated parameters to calculate the control parameters. This paper aims to present the identification of a complete current- and rotor position-dependent d-q dynamic model, which is derived by using a finite element method (FEM) simulation. The machine’s constant parameters are determined for an operation on the maximum torque per ampere (MTPA) curve. The obtained MTPA control performance was evaluated on the complete FEM-based nonlinear d-q model.

A FEM model was used to determine the nonlinear properties of the complete d-q dynamic model of the IPMSM. Furthermore, a fitting procedure based on the nonlinear MTPA curve is proposed to determine adequate constant parameters for MTPA operation of the IPMSM.

The current-dependent d-q dynamic model of the machine models the relevant dynamic behaviour of the complete current- and rotor position-dependent FEM-based d-q dynamic model. The most adequate control response was achieved while using the constant parameters fitted to the nonlinear MTPA curve by using the proposed method.

The effect on the motor’s steady-state and dynamic behaviour of differently complex d-q dynamic models was evaluated. A workflow to obtain constant set of parameters for the decoupled operation in the MTPA region was developed and their effect on the control response was analysed.

This paper aims to propose a hybrid-forecasting model for long-term tourism demand forecasting. As such, it attempts to model the tourism demand in the Philippines, which is a relatively underrepresented area in the literature, despite its tourism sector’s growing economic progress.

A hybrid support vector regression (SVR) – seasonal autoregressive integrated moving averages (SARIMA) model is proposed to model the seasonal, linear and nonlinear components of the tourism demand in a destination country. The paper further proposes the use of multiple criteria decision-making (MCDM) approaches in selecting the best forecasting model among a set of considered models. As such, a preference ranking organization method for enrichment of evaluations (PROMETHEE) II is used to rank the considered forecasting models.

The proposed hybrid SVR-SARIMA model is the best performing model among a set of considered models in this paper using performance criteria that evaluate the errors of magnitude, directionality and trend change, of a forecasting model. Moreover, the use of the MCDM approach is found to be a relevant and prospective approach in selecting the best forecasting model among a set of models.

The novelty of this paper lies in several aspects. First, this paper pioneers the demonstration of the SVR-SARIMA model’s capability in forecasting long-term tourism demand. Second, this paper is the first to have proposed and demonstrated the use of an MCDM approach for performing model selection in forecasting. Finally, this paper is one of the very few papers to provide lenses on the current status of Philippine tourism demand.

Architectural theorists have a long tradition of acknowledging the centrality of building users to architectural production. This article contributes to the discourse on architecture, actor–network theory (ANT), and users by proposing a typology of user translations ranging from supporting to tinkering to adjusting to resisting.

The research utilises an ANT-inspired ethnography of sustainable lighting scripts at the Masdar Institute of Science and Technology (MIST). It comprises semi-structured interviews with MIST designers and students, and site visits and participant observation to understand how the users interpret the scripts and how they interact and change them on a daily basis.

There is a shared understanding that users do not simply receive architectural designs but interpret and change them to suit their preferences. The findings reveal the multiple ways that users interpret and respond to the assumptions of designers and in the process, recast the relations between themselves and their material surroundings.

The research contributes to acknowledging the centrality of users to architectural design processes and the interpretation of design scripts, addressing the limitation in current literature in demonstrating the diversity of ways that users react to such scripts. The research suggests that user actions have significant implications on long-term building performance. It accordingly points to the need for devising multiple means of user involvement in the design process and allowing greater flexibility in design scripts to improve the alignment with user preferences.

This paper aims to investigate whether revenue diversification affects the financial sustainability of microfinance institutions (MFIs).

The study uses a worldwide panel data set of 443 MFIs in 108 countries for the period 2013–2018 and two-step system Generalized Method of Moments estimation model.

The study finds that revenue diversification has a significant and positive effect on the financial sustainability of MFIs.

The findings of this study actually offer important managerial and policy lessons on MFIs’ financial sustainability. Microfinance managers and policymakers should consider revenue diversification as a strategy through which MFIs can attain financial sustainability instead of overreliance on donations and government subsidies

Unlike previous studies that examined revenue diversification in the context of banking firms, this study contributes to literature by examining the impact of revenue diversification of the financial sustainability of MFIs.

The purpose of this paper is to measure Farmer’s adoption tendency towards drought shock, risk-taking networks and modern irrigation technology.

Based on this assumption, this paper evaluated the data gathered from 498 household surveys of Zhangye, Gansu province, PRC, by using the binary probit model. First, the empirical data was analyzed for evaluating the impact of drought shock and risk-taking tendencies on the adoption of modern irrigation technology by farmers. Second, the authors introduced informal risk-bearing networks with formal risks. Final, based on the empirical results, the sustainability test, along with the marginal effect analysis and the degree of impact was carried out.

The results show that the drought shock has a significantly deferent effect on the modern irrigation technology of the farmers. The probability of using technology for each level of drought loss is reduced by 15.02%. The risk-taking network has a significant role in promoting the modern irrigation technology of farmers. The probability of adoption for each additional unit of rural household labor security supply, the likelihood of adoption by farmers increased 23.11%, the probability of approval for each level of relative support, and neighborhood assistance by farmers increased by 13.11% and 17.88% respectively. This study further revealed that insurance purchases enabled farmers to adopt new irrigation technology with the probability increased by 24.99%; easily available bank loans increased the probability of farmers using irrigation technology by 31.89%. From the perspective of interactions between farmers, the risk-taking network can alleviate the inhibitory effect of drought impact towards the adoption of irrigation technology. Among the control variables, the number of years of education, the age of farming, the degree of arable land, the distance from home to the market, and the price of water all has significant effects on the adoption of modern irrigation technology by farmers.

The novelty of the study is that it illustrated the interactive influence of drought shock and risk-taking networks on the farmer’s adoption tendencies of modern irrigation technologies, the inner relationship among drought impact, the risk-taking network and the farmer’s adoption behavior and provide an interactive relationship between the formal risk-taking network and the non-risk-taking network in farmer’s technology adoption.

The purpose of this paper is to focus on an information technology (IT) deployment project in the specific field of agricultural cooperatives. It also aims to underline the importance of the IT implementation phase, but also the pre-implementation phase.

A four-year canonical action research project was conducted within a network of more than 300 agricultural cooperatives. Research was carried out both during the IT implementation and after deployment. Key information was gathered through unstructured and unofficial interviews, observations, field notes, meetings, focus groups, and documentary analysis.

Despite user resistance behavior, the findings show that information systems (IS) implementation may lead to unexpected results that extend beyond the tool’s initial objectives. Indeed, four hidden facets of the tool were revealed: inductor, symbol, pretext, and reference.

Although the research is limited to one single-case study, it puts the emphasis on in-depth research, vs cross-sectional data collection, to analyze the relationship between IT implementation initiatives and organizational intelligence. Furthermore, the authors argue that while IS literature has separately developed related theories (actor-network theory, competitive intelligence), the authors conceptualize a whole theoretic system interrelating the two above-stated theories.

The implication for IS practitioners is that, by focusing only on experiences that have occurred during IT implementation, one may disregard critical information, behaviors and knowledge from unforeseen effects that have occurred after implementation. In future IT projects, IS managers therefore need to capitalize on post-implementation knowledge, through sociology of translation and competitive intelligence, in order to anticipate potential diversions from the initial objectives. Finally, while most IT implementation methods tend naturally to manage resistance maximize users’ satisfaction and to reduce potential resistance, the authors support an alternative approach. It consists into enhancing resistance in order to anticipate and resolve latent resistance behaviors directly or indirectly related to the project.

Despite widespread literature on resistance, appropriation or acceptance during IT projects, there is little research that addresses the impact of IT projects on organizational intelligence, and the kind of behaviors that lead to its failure or success. In the case, the implemented IT tool revealed hidden structural and organizational roles, which were unanticipated by IT designers and managers.

The purpose of this paper is to analyze how “New Deal” regulatory initiatives, primarily the Securities Acts and the Securities and Exchange Commission (SEC), changed US auditors’ professional knowledge conception, culminating in the 1938 expansion of the Committee on Accounting Procedure (CAP), the first US body to set accounting principles.

The paper combines Halliday’s (1985) knowledge mandates with Hancher and Moran’s (1989) regulatory space to attain a theory-based understanding of auditors’ changing knowledge conceptions amid regulatory pressure. It draws on a range of primary and secondary sources to examine the period from 1929 to 1938.

Following the stock market crash, the newly created SEC aimed to engage auditors as a means to regulate companies’ accounting practices based on a set of codified principles. While entailing increased status, this new role conflicted with the auditors’ knowledge conception, which was based on professional judgment and personal integrity. Pressure from the SEC and academics eventually made auditors agree to a codification of their professional knowledge and create the CAP as a cooperative regulatory solution.

The paper explores the role of auditors’ knowledge conceptions in the emergence of today’s standard setting. It is suggested that auditors’ incomplete control of their professional knowledge made standard setting a form of co-regulation, located between the actors occupying the regulatory space of accounting.

The purpose of this paper is to report on research into the impact of two sequential dimensions of strategic purchasing – purchasing recognition and purchasing involvement – on the development and deployment of dynamic capabilities. The authors also examine how such dynamic capabilities impact on both cost and innovation performance, and how their effects differ for service as opposed to manufacturing firms.

The authors test hypotheses using structural equation modeling of survey data from 309 manufacturing and service firms.

From a dynamic capability perspective, the analysis supports the positive relationships between purchasing recognition, purchasing involvement, and dynamic capability in the form of knowledge scanning. The authors also find support for the positive impact of knowledge scanning on both cost and innovation performance. From a contingency perspective, data supports hypothesized differences caused by industry, whereby service-based firms experience stronger positive linkages in our model than manufacturing-based firms. Finally, emerging from the data, the authors explore a re-enforcing effect from cost performance to purchasing involvement, something that is in line with the dynamic capabilities perspective but not typically addressed in operations management (OM) research.

The research offers a number of theoretical and managerial contributions, including being one of a relative few examples of empirical assessment of dynamic capability development and deployment; examining the enablers of dynamic capability in addition to the more commonly addressed performance effect; assessing the contingency effect of firm type for dynamic capabilities; and uncovering a return (re-enforcing) effect between performance and enablers of dynamic capabilities.