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The purpose of this paper is to investigate the stability of a small scale six-degree-of-freedom nonlinear helicopter model at translator velocities and angular displacements while it is transiting to hover with different initial conditions.

In this study, model predictive controller and linear quadratic regulator are designed and compared within each other for the stabilization of the open loop unstable nonlinear helicopter model.

This study shows that the helicopter is able to reach to the desired target with good robustness, low control effort and small steady-state error under disturbances such as parameter uncertainties, mistuned controller.

The purpose of using model predictive control for three axes of the autopilot is to decrease the control effort and to make the close-loop system insensitive against modeling uncertainties.

This paper aims to propose output feedback-based control algorithms for the flight control system of a scaled, un-crewed helicopter in its hover flight mode.

The proposed control schemes are based on H_∞ control and composite nonlinear control. The gains of the output feedback controllers are obtained as the solution of a set of linear matrix inequalities (LMIs).

In the proposed schemes, the finite-time convergence of system states to trim condition is achieved with minimum deviation from the steady-state. As the proposed composite nonlinear output feedback design improves the transient response, it is well suited for a scaled helicopter flight. The use of measured output vector instead of the state vector or its estimate for feedback provides a simple control structure and eliminates the need for an observer in real-time application. The proposed control strategies are relevant to situations in which a simple controller is essential due to economic factors, reliability and hardware implementation constraints.

The proposed control strategies are relevant to situations in which a simple controller is essential due to economic factors, reliability and hardware implementation constraints. They also have significance in applications where the number of measurement quantities needs to be minimized such as in a fully functional rotor-craft unmanned aerial vehicle.

The developed output feedback control algorithms can be used in small-scale helicopters for numerous civilian and military applications.

This work addresses the LMI-based formulation and solution of an output feedback controller for a hovering un-crewed helicopter. The stability and robustness of the closed-loop system are proved mathematically and the performance of the proposed schemes is compared with an existing strategy via simulation studies.

In recent years, additive manufacturing (AM) has started to be used for manufacturing real functional parts and assemblies for critical applications in aerospace, automotive, and machinery industries. Most complex or assembled parts require internal features (IF) such as holes, channels, slots, or guides for locational and mating requirements. Therefore, it is critical to understand and compare the structural and mechanical properties of additively manufactured and conventionally machined IFs.

In this study, mechanical and microstructural properties of Inconel 718 (Inc718) alloy internal features, manufactured either as-built with AM or machining of additively manufactured (AMed) part thereafter were investigated.

The results showed that the average ultimate tensile strength (UTS) of additively manufactured center internal feature (AM-IF) is almost analogous to the machined internal feature (M-IF). However, the yield strength of M-IF is greater than that of AM-IF due the greater surface roughness of the internal feature in AM-IF, which is deemed to surpass the effect of microstructure on the mechanical performance. The results of digital image correlation (DIC) analysis suggest that AM-IF and M-IF conditions have similar strain values under the same stress levels but the specimens with as built IF have a more locally ductile region around their IF, which is confirmed by hardness test results. But this does not change global elongation behavior. The microstructural evolution starting from as-built (AB) and heat-treated (HT) samples to specimens with IF are examined. The microstructure of HT specimens has bimodal grain structure with d phase while the AB specimens display a very fine dendritic microstructure with the presence of carbides. Although they both have close values, machined specimens have a higher frequency of finer grains based on SEM images.

It was shown that the concurrent creation of the IF during AM can provide a final part with a preserved ultimate tensile strength and elongation but a decreased yield strength. The variation in UTS of AM-IF increases due to the surface roughness near the internal feature as compared to smooth internal surfaces in M-IF. Hence, the outcomes of this study are believed to be valuable for the industry in terms of determining the appropriate production strategy of parts with IF using AM and postprocessing processes.

This study aims to test the emerald model on the regional basis for the identification of the most important sources of competitiveness in the states of the US.

Using the emerald model and its assertions, data are collected over the period 1998-2013 from 47 states in the US. Multiple regression analysis is performed with a lag structure of four, six and eight years as alternative time intervals to explain the dependent variable.

The empirical results support the emerald model except for its R&D attractiveness dimension in its ability to explain competitiveness in the states of the US. In the longer term (eight-year lag), cluster attractiveness has the highest impact, followed by environmental attractiveness, ownership attractiveness, educational attractiveness and talent attractiveness. Comparison of regression models with different time lags indicates that once the very early phase is over, the impacts of most attractiveness dimensions become rather consistent across time and do not disappear.

The study contributes to the literature on the measurement of regional competitiveness by performing an overall assessment of the emerald model and by analyzing the impacts of the model’s dimensions on competitiveness over time. On the other hand, the identification of the sources of regional competitiveness paves the way for a more efficient allocation of resources regarding policies and improvement programs.

The purpose of this paper is to introduce an empirical model for house price spillovers between real estate markets. The model is presented by using data from the US-UK and London-New York housing markets over a period of 1975Q1-2016Q1 by employing both static and dynamic methodologies.

The research analyzes long-run static and dynamic spillover elasticity coefficients by employing three methods, namely, autoregressive distributed lag, the fully modified ordinary least square and dynamic ordinary least squares estimator under a Kalman filter approach. The empirical method also investigates dynamic correlation between the house prices by employing the dynamic control correlation method.

The paper shows how a dynamic spillover pricing analysis can be applied between real estate markets. On the empirical side, the results show that country-level causality in housing prices is running from the USA to UK, whereas city-level causality is running from London to New York. The model outcomes suggest that real estate portfolios involving US and UK assets require a dynamic risk management approach.

One of the findings is that the dynamic conditional correlation between the US and the UK housing prices is broken during the crisis period. The paper does not discuss the reasons for that break, which requires further empirical tests by applying Markov switching regime shifts. The timing of the causality between the house prices is not empirically tested. It can be examined empirically by applying methods such as wavelets.

The authors observed a unidirectional causality from London to New York house prices, which is opposite to the aggregate country-level causality direction. This supports London’s specific power in the real estate markets. London has a leading role in the global urban economies residential housing markets and the behavior of its housing prices has a statistically significant causality impact on the house prices of New York City.

The house price co-integration observed in this research at both country and city levels should be interpreted as a continuity of real estate and financial integration in practice.

The paper is the first research which applies a dynamic spillover analysis to examine the causality between housing prices in real estate markets. It also provides a long-term empirical evidence for a dynamic causal relationship for the global housing markets.

Competition and attempts to increase market share between organizations play an important role in business ecology. It has been determined that intensity in the institutions and death among organizations especially are of great importance. Intensity and homogeny among the organizational population are very important in the evolutionary process for them to create modern forms of institution. We have used parametric variables to collect a set of data in order to understand competition and niche among organization population. The study investigates how competition and niche affect the cluster of hotel population and their survivability. The founding of each hotel organization is differently constructed internally and different segments of the hotel population respond heterogeneously to the general process of competition. The findings show how niche and different segments of hotel population affect new organizational establishment and the evolutionary dynamics of modern organization structure, using the city center hotels of Canakkale in Turkey.

The purpose of this article is to highlight the importance of waqf in financing higher education. Nowadays, higher education is costly and this has prevented students, especially those who are self-financed, from accessing such learning environments. This paper offer an alternative solution to relieve such a situation, namely, through the application of an endowment-based or waqf educational institution. The study suggests a way to establish an endowment university by concentrating the discussion on the concept and principles of its establishment, as well as sharing the experiences of the Malaysian waqf universities and the Turkish Foundation Universities/Vakif Üniversitesi in financing their universities using waqf, i.e. a pious endowment instrument.

The empirical data were mainly collected using in-depth interviews with the universities’ higher management authorities and some of the members of the board of trustees.

The findings show that the role of waqf or pious endowment is significant in providing financial assistance to their communities as well as strengthening their academic quality. In addition, tawhidic epistemology together with morality and ethics have influenced waqf donors or founders to donate their wealth and property to enrich and sustain universities and higher education.

This article provides the experiences of the Malaysian Waqf Universities and the Turkish Foundation Universities/Vakif Üniversitesi in financing their universities using waqf. It also contains some good examples from the experience of several earlier Islamic civilizations, in particular those of the Ottoman Empire and the Mamluk Sultanate of Egypt. In addition, examples of the implementation of waqf and endowment-based universities in the UK and USA as well as the Al-Azhar University of Egypt is also included.

The purpose of this study is to empirically investigate the mediating role of knowledge management (KM) in the linkage between organizational factors, namely, organizational culture (OGCUL) and leadership and management support (LMS) and innovation in medium- and large-scale manufacturing firms in Ethiopia.

A sample of 200 firms has been used to gather data using simple random sampling and to test the proposed hypotheses. Structural equation modeling and cross-sectional design were used to analyze the data using LISREL 8.80 SIMPLIS program software tool.

Organizational factors (i.e. OGCUL and LMS) are positively associated with KM and innovation. KM constructs, namely, knowledge sharing, knowledge conversion and knowledge storage, have a significant positive influence on innovation. Knowledge sharing mediates the relationship between organizational factors and innovation.

This study has three potential limitations: first, this study is based on a cross-sectional research design. Future research should include longitudinal design to get in-depth insights into the causal inferences. Second, only a few Ethiopian medium- and large-scale manufacturing firms were included in the sample. As a suggestion for future research, other researchers can include small-scale enterprises using large sample sizes and should examine the effects of organizational factors, KM and innovation across different industries. Finally, this study has only focused on investigating the mediating role of knowledge sharing between organizational factors and innovation. Future research should test the mediating role of the KM process and its constituents (knowledge acquisition, knowledge conversion, knowledge sharing and knowledge storage) between organizational factors and specific aspects of innovation to gain a full understanding of the critical role of KM in organizational innovation.

The findings of this study would serve as a guide for policy-makers and managers of manufacturing firms in developing countries in the formulation of policies and long-term strategies. It may also provide a better understanding of the causal relationship between organizational factors, KM and innovation, which in turn has value to directors and managers in manufacturing firms in developing countries as a reference for building a good OGCUL, serving as practical guidance for effective leadership and providing organizational or management support. Specifically, the findings would have the following practical implications: first, firms need to have a combination of KM processes (such as acquisition, storage, sharing and conversion). In practice, developing countries such as Ethiopia have based their innovation strategy on knowledge and technology acquisition through encouraging foreign direct investment. It is not in doubt that Ethiopia has been benefiting from the strategy as a lot of foreign companies have opened their subsidiaries in the country. However, in the authors’ view, more emphasis on knowledge acquisition strategy would not take a firm a long time to sustain its innovative activity because it is likely available to firms operating in the same industry, as well as it may hurt a firm’s competitive advantage. In addition, by its nature, knowledge may not be retained for future use; it may expire soon. Second, the current highly impulsive and rapid change in the business environment changes the way firms have to operate and deliver products or services. Knowledge (both tacit and explicit) is a resource that can provide a competitive advantage if used well for the intended purpose. In real practice, firms often face challenges in determining where to get knowledge from and how to value or manage it. Besides, knowledge can be obtained from three sources: knowledge can exist in individuals’ minds (skills, experience, ideas and insight); knowledge can dwell in a group, which we can call collective knowledge (a team of scientists or researchers); and knowledge can be embodied in an organization's systems, tools, procedures, policies, etc. Knowledge cannot be a valuable resource unless it is obtained and used in designing or producing a product or service. To integrate knowledge with business strategies, there should be a platform or framework that helps to manage it properly. Firm managers, policy-makers and other concerned bodies would consider the three sources of knowledge to foster innovative activities and obtain a competitive advantage. In addition, the authors recommend more emphasis be placed on firm-specific factors (such as OGCUL, leadership, management support and KM) to enhance the innovative capacity of a firm. Finally, the most critical issue to be raised while designing an innovation strategy would be employees’ willingness and passion to collaborate with others to develop new ideas, share ideas or implement policies. As knowledge resides in individuals’ minds, the knowledge holder should have a passion to share it with those working with him or her. In practice, knowledge sharing depends extremely on the passion and voluntariness of the two parts: knowledge provider and receiver. Therefore, firm managers would design a platform on how to motivate individuals to share their skills, experience and ideas with others through providing incentive packages, punishment and commitment. In this regard, the authors believe that the results would help individuals who are in the position to manage or regulate the manufacturing sector in designing innovation policies, KM policies or technology management policies and business strategies.

This study provides new empirical insight into the relationships between organizational factors (such as OGCUL and LMS), KM and innovation in a large sample of firms. To date, the empirical research on these relationships has been mainly limited to descriptive case studies (Chen and Huang, 2009; Zack et al., 2009; Donate and Guadaumillas, 2011), and there is thus a lack of empirical evidence with large samples of firms. Furthermore, there is a scarcity of studies investigating the relationship between organizational factors, KM and innovation in developing countries, especially in Ethiopia. This paper intends to fill this gap and nurture future research studies in the area.

The main purpose of this paper is to investigate the relationships between seven antecedent factors (R&D strategy, top management support (TMS), customer focus (CF), organizational learning capability (OLC), creative capability (CC), organizational collaboration (OC), and supplier relationship (SR)), two innovation types (product and process), and firm performance (FP).

The paper formulates 16 hypotheses from the literature review. These hypotheses are tested using structural equation modeling with data collected from 270 managers of small and medium‐sized enterprises (SMEs) located in Turkish science and technology parks (STPs).

The findings indicate that both of product and process innovation have a strong and positive association with FP. While antecedents such as R&D strategy, TMS, CF, CC, and SR have significant impact on product innovation, other antecedents such as OLC and OC have a significant and positive impact on process innovation.

The results of this study could be used by any managers of SMEs located in STPs to improve successful innovation projects. The results also provide companies operating in Turkish STPs with useful information on how their policies and actions might affect firm innovation.

The paper provides a clarification of the reasons that may be behind a positive, a negative, or a non‐significant effect of the many antecedents on the product and process in SMEs located in Turkish STPs.

This paper explores the role of the COVID-19 pandemic in the financial and parliamentary accountability mechanisms of public-private partnership (PPP) “City Hospitals” in Turkey. Diverse and changing accountability mechanisms are explored regarding budgetary, affordability and emotions during the COVID-19 pandemic.

This is a case study of City Hospitals in Turkey. Empirical data are collected and analyzed qualitatively from publicly available government and related sources, Turkish National Audit reports (Sayistay), strategic healthcare investment plans, relevant laws, decrees and NGO reports and news articles.

Existing accountability mechanisms for arranging and/or delivering value-for-money (VfM) in Turkish PPP hospitals are weak. This provided policy makers with more flexibility to manage expectations of its citizens in dealing with COVID-19 pandemic. Political decision makers, through PPPs, created political capital for themselves by engaging in emotional accountability at the expense of better financial and parliamentary accountability.

This article contributes to the literature by articulating how roles of accountability change in crisis and introduces the concept of emotional accountability during a period of heavy infrastructure investments in City Hospitals in Turkey.