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This paper investigates consensus control in heterogeneous and uncertain multiple autonomous underwater vehicle (AUV) systems under implicit reduced visibility conditions. We address challenges such as environmental uncertainties and system nonlinearity by utilizing a unified connectivity approach to model low-visibility interactions and heterogeneous multi-AUV dynamics. Our main contributions include developing a feedback linearization model for heterogeneous multi-AUV systems that accounts for uncertainties, introducing an adaptive consensus controller based on relative positioning that effectively manages implicit visual interaction limitations and validating our strategies through stability analysis and numerical simulations. Our simulations demonstrate approximately a 60% improvement in accuracy compared to previous algorithms, highlighting the practical value of our approach in AUV recovery operations. These advancements provide a robust solution for consensus control in complex underwater environments. [ABSTRACT FROM AUTHOR]

This paper investigates consensus control in heterogeneous and uncertain multiple autonomous underwater vehicle (AUV) systems under implicit reduced visibility conditions. We address challenges such as environmental uncertainties and system nonlinearity by utilizing a unified connectivity approach to model low-visibility interactions and heterogeneous multi-AUV dynamics. Our main contributions include developing a feedback linearization model for heterogeneous multi-AUV systems that accounts for uncertainties, introducing an adaptive consensus controller based on relative positioning that effectively manages implicit visual interaction limitations and validating our strategies through stability analysis and numerical simulations. Our simulations demonstrate approximately a 60% improvement in accuracy compared to previous algorithms, highlighting the practical value of our approach in AUV recovery operations. These advancements provide a robust solution for consensus control in complex underwater environments.

In order to reduce fuel consumption and environmental pollution, the author proposes a friction heat recovery system based on the hydraulic brake by wire system of heavy-duty vehicles, the system uses the heat energy generated by friction generate electricity, and stores the electric energy in the vehicle battery. This can provide power for the lighting equipment on the vehicle. The experimental results show that after using the recovery system, the braking energy consumption is reduced, and the fuel consumption is 10% less than before, which fully demonstrates the effectiveness of the recovery system for energy conservation, and proves that the heat energy recovery system can effectively reduce fuel consumption and reduce environmental pollution. [ABSTRACT FROM AUTHOR]

The pulp and paper industry is a power-intensive technology so great attention to reducing its own energy consumption and declining the waste of available energy should be devoted. In the current investigation, the energy-exergy approach of a pulp and paper company integrated with a chemical recovery of black liquor (BL) and soda is studied actually for one year. The chemical BL recovery system that has the primary benefits to avoid environmental pollution by burning organic waste and recycling the soda is also comprehensively investigated. Natural gas (NG) and BL are utilized in power boiler (PB) and recovery boiler (RB), respectively. Moreover, in the present implementation, the chemical reactions of NG and BL are presented. The obtained results show that the percentages of energy losses in the condenser, RB, evaporators, and PB are 49.16, 19.28, 14.22, and 3.96%, respectively. The average values of exergy destruction percentages in RB and PB around the year are 41.63 and 33.5%, respectively. The maximum system overall exergy efficiency is 32.09% at an environment temperature of 290 K, whereas the energy efficiency of the system is 53.7%.

This paper is concerned with the homing process in which a multi-underactuated AUV recovery system tracks the moving mother submarine in finite time in the presence of uncertain hydrodynamic parameters and unknown environmental disturbances. In the homing stage, underactuated AUVs and the moving mother submarine are treated as followers and the leader, respectively. The multi-underactuated AUV system finite time homing problem is converted to the leader-following finite-time formation control problem. The proposed leader-following formation strategy requires only the position information of the leader. The velocity of the leader can be designed as an additional degrees of freedom to stabilize position errors of the formation. A novel robust adaptive super-twisting sliding mode formation controller (ASTASMC) is proposed, specifically the super-twisting algorithm (STA) with adaptive uncertainty estimation. Wherein, the robust adaptive law can compensate for uncertainty with unknown upper bound in real time. Therefore, the proposed controller can not only enhance the tracking accuracy but also reduce the chattering. In addition, the finite-time convergence of estimation errors and tracking errors is rigorously proved. Finally, simulation results demonstrate the effectiveness of theoretical results. • A novel robust adaptive super-twisting sliding mode finite-time formation controller (ASTASMC) is proposed for homing of multi underactuated AUV recovery system. • A finite-time robust adaptive law compensate uncertain hydrodynamic parameters and unknown environmental disturbances with unknown upper bounds which eliminates chattering and guarantees tracking accuracy. • The proposed leader-following formation strategy provides the moving mother submarine additional degrees of freedom which makes nonholonomic constraints complete. • ASTASMC shows good actuator performance with the saturation of the actuators of the multi-AUV recovery system be reasonably avoided. [ABSTRACT FROM AUTHOR]

The work presents an application that enables the calculation of the basic geometric dimensions of parachutes used in the sounding rocket recovery systems. Determining the geometry of the parachute canopy, based on the equation of aerodynamic drag, which allows to obtain the object drop velocity declared by the user. The developed application also enables the visualization of the parachute canopy geometry selected according to the specific requirements of the mission. The key element of the work is the possibility of obtaining the geometry of a single segment of the parachute canopy along with the necessary allowance for the seam, which significantly facilitates the process of making a ready-to-use parachute. As part of this study, the results of the calculations made with the use of the application were verified on the basis of data collected during the flight of the experimental sounding rocket. [ABSTRACT FROM AUTHOR]

Purpose. The purpose of the work is to determine the rational capacity and energy consumption of the onboard capacitive energy storages using a complex approach for estimating the parameters, which is based on the methods of theoretical research. Methodology. The article performs a comparative analysis of existing methodologies and approaches for determination of the onboard capacitive storages parameters for subway trains with recovery systems, formulates the advantages and disadvantages of each of them. It is determined that among the existing methodologies it is most reasonable to use a complex approach, the aim of which is to determine the rational capacity and energy consumption according to two parameters of the energy storage system – weight and payback period. A procedure for determining the rational parameters of the onboard capacitive energy storage using theoretical research methods is proposed: theoretical basis of electric traction, mathematical modeling of dynamic motion and energy processes, mathematical statistics, technical-economic and comparative analysis. Findings. According to the results of the complex theoretical researches, the economic expediency of implementation of onboard capacitive energy storages on the subway train is confirmed. The energy storage system with rational parameters of the onboard capacitive energy storage for established operating conditions in the Municipal Enterprise «Kyiv Metro» and selected experimental train of the subway is determined. The amount of saved electricity due to the implementation of the energy storage system with rational parameters is estimated. Originality. The methodology for determining the rational parameters of the onboard capacitive energy storage in terms of replacing the use of experimental research data with theoretical research, the purpose of which is to model the movement of subway trains with recovery systems using software to reduce financial costs, research time and increase their accuracy. The research on determination of quantitative indicators of recovery electricity for the analysis of energy saving reserves was further developed in the subway. Practical value. The results of theoretical research can be the basis for the creation of full-scale samples of subway trains with onboard capacitive energy storages. The researches will create recommendations for the design of innovative energy-saving subway trains with improved technical and economic characteristics that can increase the efficiency of the transportation process in the subway.

This paper addresses the coordinated control of heterogeneous multi-UUV system in low-visibility underwater environments. It introduces a joint connect directed graph to model low-visibility interactions, addressing the complexities of interaction and dynamic heterogeneity. The study also develops implicit coordinated control algorithms for heterogeneous UUVs, relying solely on relative position state. A key theoretical contribution is the stability proof for multi-UUV operations under heterogeneous and low-visibility interaction conditions. The proposed algorithm's effectiveness and robustness are validated through simulations, highlighting its potential practical utility in real-world complex underwater recovery tasks. • Established a model for a heterogeneous multi-UUV recovery system under low-visibility scenarios. • Developed implicit coordinated control algorithms for heterogeneous UUVs, requiring only relative position data. • Provided proof of stable multi-UUV recovery under heterogeneous conditions. • The effectiveness and robustness of the proposed algorithm are validated through simulations. [ABSTRACT FROM AUTHOR]

The consensus control of multiple AUVs recovery system is the key to complete the multi-AUV recovery mission. This paper proposes consensus control of multiple AUVs recovery system under switching communication topologies and time delays including input delay and communication delay. Consensus control algorithm for a multi-AUV recovery system is assumed to guarantee all the members to reach a common motion state and desired point. The mothership is regarded as the point which all AUVs have to catch up with, the recovery problem of multiple AUVs can be seen as the consensus problem of multi-agents system. A randomly changing consensus stability criteria and stabilization conditions are derived by a suitable Lyapunov-Krasovskii functional for the Markovian switching recovery system with time delays, and then a consensus controller design method is derived. Finally, the correctness of the proposed method is proved by simulation experiments.

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Due to increased environmental awareness, the issue of recycling and disassembling damaged or malfunctioning products after consumption to obtain useable parts for remanufacturing has become essential. This study considers a hybrid production system with both external and internal reverse logistics in which the external recycled products are utilised for remanufacturing to satisfy demand first, and then the ordinary manufacturing process may supplement this if there is any shortage in production. In addition, the defective items produced internally by either the manufacturing or the remanufacturing process can also be repaired by a remediation process. The objective of this study is to determine the optimal strategy for the manufacturing, remanufacturing, disposal, and remediation rates. Three conditions are considered in which the production strategy varies with different yield rates and capacity limits. The impacts of related factors on the production strategy are investigated to probe the trade-offs between product consumption and environmental protection. [ABSTRACT FROM PUBLISHER]

Thermoelectric generators are long-life electricity generators that operate according to the Seebeck thermoelectric effect and produce DC voltage by utilizing the temperature difference on hot and cold surfaces, without moving parts. The ability to generate electricity directly in any situation where the temperature difference between the surfaces of the thermoelectric modules arises makes it possible to generate electricity from the first time in the exhaust systems of the internal combustion engines. It is very important to examine the recovery of the thermoelectric generators in the heating process in the internal combustion engines due to the reduced generator efficiency at low revs. In this study, thermoelectric generators were used to provide exhaust heat recovery in heating process of an internal combustion gasoline engine, electrical gains obtained at three different temperature averages were investigated and experimental and simulated results were compared. A maximum ΔT = 165 °C temperature difference was obtained between the module surfaces. In the experiments performed, ΔT = 165 °C, RL = 10 Ω load resistance, maximum 6.75 V voltage, 0.65 A current is obtained. Experimental and simulation results are generally in coherence.

Termoelektrik jeneratörler, Seebeck termoelektrik etkisine göre çalışan, sıcak ve soğuk yüzeylerde sıcaklık farkından yararlanarak DC gerilim üreten, hareketli parçaları olmayan uzun ömürlü elektrik üreteçleridir. Termoelektrik modüllerin yüzeyleri arasında sıcaklık farkının meydana geldiği her durumda doğrudan elektrik üretebilmesi içten yanmalı motorların egzoz sistemlerinde ilk çalışmadan itibaren elektrik üretimini mümkün kılmaktadır. Düşük devirlerde alternatör veriminin azalması sebebiyle termoelektrik jeneratörlerin içten yanmalı motorlarda ısınma sürecinde geri kazanımının incelenmesi oldukça önemlidir. Bu çalışmada termoelektrik jeneratörler kullanılarak içten yanmalı benzinli bir motorun ısınma sürecinde egzoz atık ısı geri kazanımı sağlanmış, oluşan 3 farklı sıcaklık farkında elde edilen elektriksel kazanımlar incelenmiş, deneysel ve benzetim sonuçları karşılaştırılmıştır. Modül yüzeyleri arasında maksimum ∆T=165 °C sıcaklık farkı elde edilmiştir. Yapılan deneylerde ΔT=165 °C, RL=10 Ω yük direncinde maksimum 6.75 V gerilim, 0.65 A akım elde edilmiştir. Deneysel ve benzetim sonuçları genel olarak uyumludur.

A simple lumbar spine (low back) and extensor (muscle) orthopaedic recovery system have been developed in this study. The system is designed to assist in overcoming logistics constraints associated with treatment and recovery of musculoskeletal ailment and neurologic injuries by implementation of controlled therapeutic exercise without unwarranted complexities and obstructions especially for low income earners. The structural frame comprising of the head rest, back rest, bed rest, hand rest and the leg support was designed and fabricated. The system derives its reciprocating motion from the combination of an electric motor and a slider crank mechanism. The system was designed for a maximum body mass of 125.80 kg. The slider crank mechanism attains a maximum stroke of 175 mm. The orthopaedic recovery system would go a long way to effectively mitigate the socioeconomic burden and condition of individuals suffering from chronic musculoskeletal pain and impaired function at the lumbar area. Furthermore, the living condition, resourcefulness and productivity of victims of musculoskeletal impairment would be greatly improved; and sickness related expenses are also expected to reduce due to enhanced recovery rate of low back orthopaedic patients. [ABSTRACT FROM AUTHOR]

In this article, a single-product recovery system is studied. Used products are collected from customers and kept at the recoverable inventory warehouse for future recovery. The constant demand rate can be satisfied either by newly produced products or by recovered ones (serviceable inventory), which are regarded as perfectly as the new ones. Excess demand is completely backordered. Following an exact analytical approach, the optimal production and recovery policy is obtained. A numerical cost comparison of this model with the corresponding one without backordering is also performed. The results are general, as they were valid for finite and infinite production and recovery rates. [ABSTRACT FROM AUTHOR]

Waste heat recovery systems, which make use of waste sources for their input energy, have considerable importance in industry since they utilize streams, which will be disposed to nature if not employed. Ship’s engines are one of the places, where a large amount of energy is wasted in different forms. In the present article, the idea of making use of these loss streams and consequently producing useful power in the outlet is proposed in the form of two systems. In the first system, the only stream of exhaust gases is utilized, while in the second system, the jacket cooling water is used together with the engine exhaust gases. Screening in the working fluids is conducted in order to select appropriate fluids, which have suitable characteristics in the physical, safety, and environmental aspects. The analyses indicate that using R600a presents the highest net power output, which reaches to the value of about 575 kW at the most. Comparison of the two introduced systems shows that preheating the working fluid by the jacket cooling water makes the better operation of the system and the power output is increased up to about 31-58% in different fluids. The lowest payback period in the systems is achieved through the use of R600a as the working fluid, which is about 3.48 year in the second system. [ABSTRACT FROM AUTHOR]

To reduce the communication burden and enhance the data processing capability of the multiple unmanned underwater vehicle (multi-UUV) recovery system, a distributed event-triggered multi-UUV coordinated control method under time-delay conditions is proposed. The multi-UUV recovery problem can be transferred into a leader-following consensus problem. For each UUV to be recovered, the controller updates depend on its own trigger function. Also, sufficient conditions and boundary conditions on leader-following consensus are presented, respectively. The simulation results show that the proposed controller is effective, robust, and energy-efficient for the multi-UUV recovery system. • Mathematical models for coordinated control of multi-UUV recovery were developed to consider unfavorable factors in real underwater environments. • A distributed event-triggered control method for multi-UUVs was proposed to reduce system updates while considering data processing capabilities and time delays. • Sufficient and boundary conditions exclude Zeno behavior.Numerical simulations demonstrate that the proposed controller is effective, robust, and energy-efficient for the multi-UUV recovery system. [ABSTRACT FROM AUTHOR]

The paper presents various schemes of flight of a separated part of the first stage, equipped with the reactive recovery system taking a two-stage oxygen-kerosene medium class launch vehicle assembled on the basis of the results of ballistic design and similar to theFalcon-9 launcher in its power mass characteristics. The results of assessing the change in the payload mass placed into the low-earth orbit by the launcher, estimating the change in the value of the mass ratio of the first-stage recovery system and limit values of aerodynamic and heat loads of the first stage in the phase of recovery depending on the flight scheme are presented. The values of the mass ratio of the recovery system depending on the flight scheme are compared with that of the mass ratio of an aircraft-type recovery system. The advantages of the reactive recovery system in comparison with the aircraft-type recovery system are pointed out. The necessity of using an additional retroburn by restarting the service propulsion system of the stage prior to the re-entry with the aim of reducing aerodynamic and heat loads. It is shown that the reactive way of recovery can be implemented with acceptable energy losses only by making an intermediate landing on the complex located along the flight course.

Thermoelectric generators are long-life electricity generators that operate according to the Seebeck thermoelectric effect and produce DC voltage by utilizing the temperature difference on hot and cold surfaces, without moving parts. The ability to generate electricity directly in any situation where the temperature difference between the surfaces of the thermoelectric modules arises makes it possible to generate electricity from the first time in the exhaust systems of the internal combustion engines. It is very important to examine the recovery of the thermoelectric generators in the heating process in the internal combustion engines due to the reduced generator efficiency at low revs. In this study, thermoelectric generators were used to provide exhaust heat recovery in heating process of an internal combustion gasoline engine, electrical gains obtained at three different temperature averages were investigated and experimental and simulated results were compared. A maximum ΔT = 165 °C temperature difference was obtained between the module surfaces. In the experiments performed, ΔT = 165 °C, RL = 10 Ω load resistance, maximum 6.75 V voltage, 0.65 A current is obtained. Experimental and simulation results are generally in coherence. [ABSTRACT FROM AUTHOR]

A depth filtrating system with rotatable and taper-shaped filter column was reported to highly remove and recover oil from wastewater. In the work, structure filters made of kapok fibers were prepared by air-laying-bonding method. The oil removed from wastewater was then recovered from the oil-loaded filter by rotating the filter column, and the resulted filter was reused. The filtrating system demonstrated extremely high oil/water separation in which oil was completely retained by the filter at the first 20–100 min while water passed through the filter’s body with a flow rate of 560 mL/min using 11,500–13,150 mg/L vegetable oil or diesel polluted water. A total of 47.6–176.4 L clean water was collected after four cycles of filtration and centrifugation. The separating process depended on filter’s structure (packing density) and properties of model oils. The wetted filters which absorbed up to 795.6 g (32.31 g/g) of oils were centrifuged to recover 80–91% of the oils. The sorption capacity appeared to become constant until 4 cycles of filtration after an apparent drop of 1–6 g/g in the second cycle, because of unrecoverable residual oil (2–5 g/g). The decrease of flow rates was favorable to filtration of low viscous oil. [ABSTRACT FROM AUTHOR]

This paper presents a novel task allocation method for multiple unmanned underwater vehicles (multi-UUV) recovery systems. Specifically, a bilevel model that enjoys the advantages of centralized and distributed methods is constructed for mothership and cooperative constraints. In the centralized upper-level, an improved Gaussian mixture mode (IGMM) is presented, and an improved discrete crow search algorithm (IDCSA) is proposed. Thus, the leaders are clustered into subgroups, and the matching relationship between motherships and subgroups is established. In the distributed lower-level, the proposed consensus-based bundle algorithm with group constraint (CBBA-GC) addresses the allocation problem between subgroups and heterogeneous follower UUVs. It is found that the proposed bilevel method can achieve conflict-free and load-balanced multi-UUV recovery task allocation when the communication capability of each UUV and motherships recovery ability are heterogeneous. • In view of the unfavorable factors that restrict the heterogeneous multi-UUVs recovery progress in the real environment, mathematical models for practical task allocation are constructed. • Combining the advantages of centralized and distributed methods, a new bilevel allocation method is proposed to generate UUV subgroups and allocate subgroups to suitable motherships. • Several algorithms are selected according to the properties of the different levels, and were modified with proposed improved methods to meet the requirements of the multi-UUVs recovery task allocation, which can fully prove the effectiveness and robustness of the bilevel method. [ABSTRACT FROM AUTHOR]

This paper addresses a distributed cooperative dual closed loop controller for the rendezvous process of the crowded underactuated AUV swarm recovery system in 3-dimensional space. Inspired by biological behaviors, the rendezvous process of the AUV swarm transforms into a flocking problem. Different from the traditional flocking problem, it is difficult to obtain the accurate position information of AUV in underwater environment. In the outer loop, the proposed velocity-attitude consensus protocol only uses the velocity and attitude information of neighbors in the communication range of AUV to handle the flocking issue of the AUV swarm. Moreover, the protocol guarantees the AUV swarm separation, cohesion, velocity matching and attitude synchronization, if no collision and the dynamically switch topology connectedness are preserved at the initial position. In the inner loop, the proposed fractional integral terminal sliding mode controller provides practical available control input for the actuator. In addition, the exponential consensus of velocity and attitude and the locally asymptotic stability of the system are rigorously proved by max-min, graph theory and Lyapunov method. Finally, straightforward simulation results confirm the feasibility of the distributed cooperative controller. • Underactuated AUV swarm rendezvous problem is uniquely decoupled into velocity-attitude synchronization flocking at the kinematic level (coordination layer) and the motion control problem at the dynamic level (executive layer). • In the flocking phenomenon, the three-dimensional nonholonomic model of AUV is initially studied, and the nonlinear terms in the model are analyzed, which makes it feasible to design a simple linear control protocol. • Without any position information and complex nonlinear potential field functions, the proposed control protocol can guarantee separation, cohesion, velocity matching and attitude synchronization. • The velocity and attitudes of the underactuated AUV swarm exponentially converge to synchronization, respectively, which can ensure the efficiency of the rendezvous process. • Reasonably reduce the communication and computational burden by setting communication range and dynamic proximity network. [ABSTRACT FROM AUTHOR]

This work investigates a possible application of an integrated heat recovery system with an indirect evaporative cooling section (IEC) into the air extraction and a dehumidification device into air delivery. System operation is then simulated in different climatic conditions and the energy consumptions are compared with the energy required by the same system without the IEC section. [ABSTRACT FROM AUTHOR]

Alternative methods for electricity production are needed in view of the scarcity of natural sources resulting from population growth and the consequent demand for energy. The inefficient use of energy requires new recovery processes in order to increase the system's gains. The use of Seebeck modules (TEG) have been shown the novel output of power recovery using waste heat energy. This work proposes a recovery plant from waste heat starting from a geometry optimization of exhaust duct. The distance between each TEG and surface was varied lengthwise to flow, creating a thermally resistive air layer, and from a heuristic optimization process, good results about equalization on surface temperature were found by finite element analysis. The thermoelectric modules used were tested in real conditions and results compared with data sheet. Finally it is exposed an electrical arrangement for a 42 TEG MPPT power plant. The novel design shows a low surface temperature gradient that allows TEG work closely to maximum efficiency condition and distant of mechanical failure. [ABSTRACT FROM PUBLISHER]

Imposition of strict environmental protection acts and the imperative need of best possible allocation of resources have given birth to the concept of “low carbon logistics.” Environmental laws force the manufacturers to extend their existing supply chains to form a closed loop supply chain (CLSC) through the setup of an efficient recovery system. In this paper, we attempt to deal with the environmental issues presented in the design of CLSC networks. The CLSC network proposed in the paper consists of four echelons in the forward chain and five echelons in the backward chain. To consider the environmental issues in the proposed CLSC network, we formulate a bi-objective integer nonlinear programming problem, and in order to solve it we propose an Interactive Multi- Objective Programming Approach Algorithm. This model determines the optimal flow of parts and products in the CLSC network and the optimum number of trucks hired by facilities in the forward chain of the network. A numerical experimentation of the proposed model to validate the applicability of the model is done with the help of data from a real life case study. The case presented in the paper is based on a geyser manufacturer, and its application on the model provides us with the underlying tradeoffs between the two objectives. The model also results in a very interesting fact that with the implication of the extended supply chain, a firm can create a green image of their product which eventually results in an increase in their demand while significantly reducing their usage of transportation in both directions. [ABSTRACT FROM AUTHOR]

In this research a closed loop supply chain is designed which incorporates reverse logistics and forward logistic system simultaneously. In the design of reverse logistic system, recovery options are embedded in traditional supply chain for treating returned products. The recovery system includes collection centres, remanufacturing plants and disposal centres. Since the product return is supply driven, there is an uncertainty about it. In the proposed configuration for closed loop supply chain, the optimised configuration for supply chain in terms of locating recovery plants is developed. Accordingly, a fuzzy mixed integer linear programming model develops to deal with the uncertainty of returning products by customers. A general-purpose solver (LINGO 8.0) and a Meta heuristic approach (genetics algorithm) are implemented to solve the proposed model. The answers are compared by defining indexes and then the optimal answer, configuration and variables are identified. This solution will suggest a new design of supply chain network in which waste of materials is minimised and the new raw materials are necessary only when the used products may not be recovered by recovery options. [ABSTRACT FROM PUBLISHER]

One of the major concerns in a reverse supply chain management (RSCM) system is dealing with returned products (due to being defective or obsolete) through a reverse logistics, such that the returned items reach their final destinations with minimum cost. In this paper, for managing returned products, a comprehensive seven-layer recovery network is designed, including primary customers, collection/redistribution centers, recovery, recycling and disposal centers, and secondary customers. The network is mathematically modeled as a mixed integer linear programming (MILP) model whose optimal solution determines the proper collection and recycling centers for the reverse and forward logistics of returned and recovered products, such that the total cost is minimized. Since the problem belongs to the network design class of problems which is NP-hard, the time for obtaining an optimal solution grows exponentially as the number of binary variables increases. Therefore, a new Tabu search-based heuristic method is developed for computing optimal or near-optimal solutions for the recovery system. Also, the Taguchi experimental design technique is employed for parameter tuning of the heuristic and coming up with a robust design. The efficiency and effectiveness of the proposed heuristic method has been evaluated through comparisons with a recently developed SA method, as well as the global optimal solutions of the model. Experimental results showed that the new Tabu search-based approach outperforms the SA method and has an average solution gap of 3.28 % with optimal solutions and a robustness of 2.18 %. [ABSTRACT FROM AUTHOR]

This study focused on the H∞ consensus tracking of the recovery system of multiple unmanned underwater vehicles (UUVs) with switching networks and disturbances. Considering the complexity of the marine environments, the information communication was described by a switching topology that obeys the Markov chain. A novel H∞ consensus protocol was proposed for the multi-UUV recovery system with switching communication topology and disturbances. By using the Lyapunov–Krasovskii functional and linear matrix inequality, the sufficient conditions for the multi-UUV recovery system to achieve stochastic H∞ consensus were deduced, and based on the above conditions, the controller gain was designed. Finally, three-dimensional simulations of the multi-UUV recovery systems were performed. The simulation results validated the feasibility of the H∞ control strategies. • The multi-UUV recovery problem with communication constraints is converted into an H∞ consensus tracking problem. • An H∞ consensus protocol with the Markov switching networks and time delay for a multi-UUV recovery system is proposed. • The H∞ consensus controller gain was designed such that multiple UUVs finally reach the state consistent with the mothership. [ABSTRACT FROM AUTHOR]

Abstract: The performance of three combined systems using reverse osmosis to produce drinkable water and a Rankine cycle which produces mechanical power have been analyzed and compared. The RO subsystem incorporates a power recovery unit (a hydraulic turbine in the first two cases and a pressure exchange unit in the third case). The coupling between the RO and Rankine subsystems is only mechanical in the first case (the Rankine cycle provides mechanical power to the pumps of the RO subsystem), while in the two other cases the coupling is both mechanical and thermal (the heat rejected by the condenser of the Rankine cycle is transferred to the seawater). The minimum values of the Rankine cycle mass ratio for the three systems and the maximum operating temperature for the two last systems have been established. Energy and exergy efficiencies are also compared for identical entering parameters. [Copyright &y& Elsevier]