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This paper aims to offer a simultaneous design approach for helicopter having swept anhedral blade tip shape and helicopter flight control system (HFCS) to minimize controller cost.

By considering previously stated offer, control-oriented models and a stochastic optimization method are applied to minimize controller cost of the HFCS.

Using simultaneous design approach for helicopters having blade tip swept and blade tip anhedral causes considerably less control effort than the helicopters not benefiting this related design approach.

Simultaneous design approach for helicopters having blade tip swept and blade tip anhedral is applicable to consider fuel economy.

One important novelty of this paper is using simultaneous approach for determining optimum shape of blade tip swept and anhedral. Another considerable novelty of this paper is also using a stochastic optimization method called simultaneous perturbation stochastic approximation for previously mentioned purpose. In this paper, it is also reached that using simultaneous design approach for swept anhedral helicopter blade tip shape and HFCS causes less control effort than the helicopters not using this approach. This leads to less fuel consumption and green environment.

THE speed at which a valve is coming to rest on its scat at the moment of closing is one of the factors deciding the amount of gases passed through the valve. The inertia forces, however, act for a very short time on the valve at this moment, and this is the reason why normal considerations in the strength of valves are not accurate; it would be better, when designing the valve, to use approximate calculations giving the possibility of orientation among the various factors coming into consideration, than to leave all this to experimental practice.

The purpose of this paper is to introduce a method based on the fuzzy correlation for modelling of active and reactive powers from the substations of the electrical distribution systems, at the peak load.

Based on the correlation theory, the fuzzy models of the loads can be obtained using a new algorithm. If in the case of the principal/connection station there is sufficient database information for a good forecasting of the load, then for those substations where data are missing (there is no continuous monitoring or the measuring system can be broken for a while) the forecasting of the load can be performed using the correlation studies. The starting point of the algorithm is statistical analysis of the active and reactive curves of the substations and utilization of a fuzzy linear regression model. This can be made for different time windows (window 24 h, window 7 h, etc). The window 24 h can be used successfully to estimate the hourly load on any substation. The other time window (7 h) can be used in the peak load estimation of the substations, using the maximum value of the active power recorded in a reference substation.

The numerical data show that the fuzzy correlation models can be used with very good results for determination of the peak load corresponding distribution substations, and further with the state estimation of the system. In this study, the influence of the time window size is presented in detail, and the fuzzy correlation models for the peak loads from the distribution substations are obtained.

Starting from the correlation theory, a method of fuzzy modelling of active and reactive powers from the substations of an electrical distribution system is proposed.

This paper aims to investigate ternary Al-Co-Ti alloy system with various Co compositions. Structural characterization of AlxCoy-2Ti2 alloys were performed by means of light microscopy, scanning electron microscopy, X-ray diffraction and electrochemical test. The effect of the addition of 5, 10, 15, 20, 25, 30 per cent Co and 2 per cent Ti on the structural evolution shows that both intermetallic compounds formation and structure morphology are related to corrosion resistance at the as-elaborated state as after subsequent heat treatment at 500°C during short time. According to the microstructural characterizations, the authors can notice that the substitution of Co has an important effect on the corrosion resistance and plays a role for the formation of the passive film.

The alloys in this study were obtained by a high-frequency induction fusion. Powders from Al, Co and Ti (99.999 per cent) in proportions defined according to the composition aimed of alloy have been used. The total mass of the sample to be elaborated lies between 8 and 10 g. Cold compaction was achieved for mixed powder intended for high fusion frequency (HF). For electrochemical tests, the sample was cut by a diamond wheel to obtain a square section of dimensions 1 cm². Afterward, this sample was connected with a Cu electrical wire. The last stage is the envelope in an acrylic resin realized in a plastic mold. The used electrolyte is a salt environment of 3.5 per cent NaCl (35 g of NaCl by liter of distilled water at room temperature [25 ± 1°C], aerated and with moderated agitation V = 250 r.min⁻¹). This mold is kept in ambient air for 10 min to allow the resin to solidify.

The aim of this work is to establish the influence of the addition of Co and Ti on structural change and related corrosion behavior improvement in Al. Particular attention is accorded to Al-15 per cent Co-2 per cent Ti alloy.

Among the studied alloys with different Co contents, a precise composition of 15 per cent Co and 2 per cent Ti appears to have interesting electrochemical characteristics regarding the corrosion potential, the corrosion current and particularly the corrosion rate, which is very small when compared to that of other alloys, as well in the as-solidified state than after heat treatment. This composition is located halfway between the stainless steel 304 and the Al-Fe and Al-Co-Ce alloys.

The purpose of this paper is to present the varied roles played by the University of Lódz (UL) in maintaining and restoring the natural capital of a city as a driver for sustainable city development. The higher education institution can be perceived as visionary, originator and executor of natural capital projects.

The paper analyses three cases performed by the Faculty of Biology and Environmental Protection, UL, in the city of Lódz. The activities are based on different scales ranging from city-wide to local, e.g. river and green infrastructure, and which vary in character from policy planning to implementation.

Natural capital projects influence city development on different levels: by the initiation of legal protection, by the implementation of rehabilitation concepts for rivers and by influencing the strategic documents for mid-term and long-term urban development.

The university has the potential for multidisciplinary engagement in the development of urban sustainability. In large-scale projects, academics play a more conceptual role, in capacity building and knowledge transfer, while in local-scale implementations, their role includes innovation, know-how and technology transfer. Moreover, it may act as a reinforcement hub, by safeguarding and strengthening the natural capital of the city.

The purpose in this paper is to develop a systematic literature review aiming to reveal innovation opportunities associated with the thematic collaboration and trust in the reverse logistics field.

The authors adopted a parallel analysis approach segregating the systematic literature review papers in two groups at NVivo®, collaboration and trust in the supply chain and collaboration and trust in reverse logistics, aiming to explore in the first group of papers insights for innovation on collaboration and trust in reverse logistics. The content analysis strategy was supported by the knowledge exchange theory described in Gravier et al. (2008).

Reverse logistics is hardly dissociated from broader sustainable supply chain management approaches, which make all considerations on collaboration and trust designed for such approaches valuable and valid for reverse logistics. Collaboration and trust concepts in supply chain and in reverse logistics contexts are quite similar, while collaboration/trust is mandatory for managing networks in sustainable approaches and in reverse logistics, as well. Downstream and upstream, the chain disruptive innovation business models may be developed between focal companies and returns system third-party logistics providers, fourth-party logistics providers or end-customers, in a business-to-customer collaboration approach. Several collaboration technologies are listed in three perspectives: knowledge sharing, knowledge generation and knowledge implementation.

This study uses a specific protocol for the systematic literature review, and due to inclusion and exclusion criteria, other protocols can provide different results. The strategy of analysis under the knowledge exchange perspective may give a type of result different from other perspectives.

This research systematizes the existing knowledge on the collaborations and trust, which is a priority basis for reverse logistics, providing insights to researchers and practitioners in the area and identifying an agenda for future studies.

The purpose of this paper is to determine dependencies between a rotor-blade shape and a rotor performance as well as to search for optimal shapes of blades dedicated for helicopter main and tail rotors.

The research is conducted based on computational methodology, using the parametric-design approach. The developed parametric model takes into account several typical blade-shape parameters. The rotor aerodynamic characteristics are evaluated using the unsteady Reynolds-averaged Navier–Stokes solver. Flow effects caused by rotating blades are modelled based on both simplified approach and truly 3D simulations.

The computational studies have shown that the helicopter-rotor performance may be significantly improved even through relatively simple aerodynamic redesigning of its blades. The research results confirm high potential of the developed methodology of rotor-blade optimisation. Developed families of helicopter-rotor-blade airfoils are competitive compared to the best airfoils cited in literature. The finally designed rotors, compared to the baselines, for the same driving power, are characterised by 5 and 32% higher thrust, in case of main and tail rotor, respectively.

The developed and implemented methodology of parametric design and optimisation of helicopter-rotor blades may be used in future studies on performance improvement of rotorcraft rotors. Some of presented results concern the redesigning of main and tail rotors of existing helicopters. These results may be used directly in modernisation processes of these helicopters.

The presented study is original in relation to the developed methodology of optimisation of helicopter-rotor blades, families of modern helicopter airfoils and innovative solutions in rotor-blade-design area.

This chapter deals with the progressive political mobilisation of peasantry in Poland, its institutionalisation, mainly in inter-war period, and its political appropriation by the Communist regime after 1945, when State socialism needed to ground itself in Polish national history and political traditions. These various mobilisations could be labelled as ‘populist’ because of their peasantist components and ideological trends, but the chapter considers them rather as a political form of representation, which political uses by actors fluctuate according historical contexts. The first part analyses the emergence of peasant movement and the success of peasant political parties in pre-1939 Poland. The second part shows how formers activists of these parties tried to produce themselves as the only historical heirs of the peasant movement, in opposition to the new, Leninist, peasant party of the Communist Poland. In the third and last part, the chapter analyses how the Communist official peasant party, the ZSL, invented new political traditions, mainly by historicising strategies, in the aim to encapsulate the peasant form of representation in its identity.

The purpose of this study was to analyze the possibility of using combat aircraft including decommissioned as a platform for launching and carrying space rockets with satellites (nano and microsatellites). Thus, an airborne-launcher-to-space-system may be attractive to countries without ground-based space rocket launch sites.

For considered launch-to-orbit system configurations, simulations of space rocket effects on aerodynamic characteristics were performed using computational fluid dynamics (CFD ANSYS Fluent) methods. In addition, experimental studies were performed in a wind tunnel to verify the numerical simulations. Discrete models of the aircraft structure were developed for analysis using finite element method (FEM). The analysis of simulated structural properties of the models was carried out to test its stiffness and mass characteristics important for solving the static and dynamic problems of the structure. The validation analyses of aircraft models were based on mass distribution estimation and matching the stiffness properties of the individual airframe structural assemblies.

The results of numerical analyses and tunnel tests indicate that the influence of carrier rockets on the change of aerodynamic and strength characteristics of the airframe is rather negligible. The aircraft can be used as launching platforms for space rockets. Simulations have indicated that the aircraft will successfully perform a mission of taking away and launching a rocket of at least about 1,000 kg total weight with a 10 kg space payload included.

The combat aircraft can be used as launch platforms for space rockets, and the air/rocket set can become the equivalent of responsive space assets for countries with small space budgets.

The work presents original results obtained by the authors during a preliminary design of a low-cost satellite launch system consisting of a carrier aircraft and a space rocket orbiter. The possibility of using decommissioned combat aircraft as air-launch-to-orbit platforms was taken into consideration. In the absence of aircraft design documentation, reverse engineering methods and techniques were used to develop aircraft geometry and airframe strength structure. Use of CFD, FEM and simulation methods to evaluate system capabilities was demonstrated. Numerical results from CFD simulations were finally verified in experimental tests.