Structural design is another strategic point in developing a vibration protection system with mechanisms of negative and quasi-zero stiffness. Missing this stage of the design and errors in designing the structure of mechanisms predisposed to unstable motion can ruin the development idea. A method of structural design of function-generating mechanisms for such systems is proposed. This includes the type and number synthesis of the mechanisms, making this process less empirical and more reasonable and bringing a great number of new candidates. The atlases of the mechanisms for seat suspensions and bogie secondary suspensions for carbody of high-speed trains are elaborated. The method fundamentals are (a) the function-generating mechanism is to be perfectly structured, that is, with a minimal number of redundant constraints; (b) due to unstable motion and transposition of clearances in kinematic pairs, the mechanism with negative stiffness must not directly join the input and output structural elements of function-generating mechanism to avoid structural indeterminacy; (c) mechanisms with negative stiffness shall be joined to the input structural element, and with no more than two kinematic pairs, one of these two is to be higher; (d) an external damping mechanism can be removed from function-generating mechanisms without degradation of the system performance.

Some types of conventional mechanical, pneumatic or other vibration protecting mechanisms with parametric elements of positive stiffness, i.e. having a given load capacity, may reveal the negative or quasi-zero stiffness in small. However, this is considered as a side effect and have no engineering feasibility to be realized in commercial vibration protection systems. This disadvantage can easily be eliminated if join the redundant mechanisms with parametric elements of negative and quasi-zero stiffness in large. Redundant mechanisms can drastically improve the quality of vibration protection in a certain combination and interaction with commercial systems, and without a destroying the system workspace. In this manner, one may arrange a seat suspension, independent wheel suspension, cabin's mounting, table or platform for measuring instrument and in this way protect a man-operator or passenger, power unit, onboard or stationary electronics, and cargo container. It was shown that the mechanisms with negative and quasi-zero stiffness in large, being properly joined to commercial vibration protection systems by using transmissions with short kinematic chain, increased 5 to 57 times the quality of vibration protection in the whole infra-low frequency range including nearly zero values. In some practical cases, this advantage reaches 100 to 300 times and more

Uncertainty is always present in engineering design. Manufacturing processes create deviations from the specifications, operating conditions vary from the ideal, and some parameters are inherently variable. Optimization with deterministic inputs can lead to poorly performing designs. Optimization under uncertainty (OUU) is the optimization of systems in the presence of random parameters or design variables. The objective is to produce robust and reliable designs. A design is robust when the objective function is less sensitive to inherent variability. A design is reliable when it is less prone to violating a constraint when accounting for the variability.*

Stability in large of the systems with mechanisms of negative and quasi-zero stiffness plays an important role for improvement of the infra-low vibration protection. These mechanisms are predisposed to chaotic vibration motion. Analysis of chaotic vibration and comparative selection of the mechanisms are to be reasonable steps before deciding next steps in designing the vibration protection systems. Their dynamic behavior can be diagnosed and predicted by the qualitative and quantitative methods for analysis of chaotic motion. An algorithm has been developed to study chaotic motion of the mechanisms, and the conditions of dynamic stability of the systems with such mechanisms are formulated. The algorithm is based on the Lyapunov largest exponent and Poincare map of phase trajectory methods and includes (a) formulation of chaotic motion models and criterial experiments for the mechanisms and systems, (b) technique of comparative analysis of the models, (c) computation procedure to estimate their dynamic stability in large, (d) formulation of design and functional parameters for providing stable motion of the systems in the infra-frequency range, including near-zero values. Validity of the algorithm is demonstrated through the development of active pneumatic suspensions supplied with passive mechanisms of variable negative stiffness.

Up to this point in the book, all of our optimization problem formulations have had a single objective function. In this chapter, we consider multiobjective optimization problems, that is, problems whose formulations have more than one objective function. Some common examples of multiobjective optimization include risk versus reward, profit versus environmental impact, acquisition cost versus operating cost, and drag versus noise.

Gradient-free algorithms fill an essential role in optimization. The gradient-based algorithms introduced inare efficient in finding local minima for high-dimensional nonlinear problems defined by continuous smooth functions. However, the assumptions made for these algorithms are not always valid, which can render these algorithms ineffective. Also, gradients might not be available when a function is given as a black box.

HNLMS De Ruyter and De Zeven Provinciën were the last cruisers of the Royal Netherlands Navy. In a period most ships were transferred from abroad (UK and USA), they were the largest post-war naval ships of Dutch manufacture. For years they were besides aircraft carrier Karel Doorman flagships. Construction of both ships started before World War II, but they did not enter service until 1953. After twenty years of service they were sold to Peru.

In May 1973 De Ruyter was renamed Almirante Grau. Modernizations 1985-88 and 1993-96. Decommissioned September 2017 (served 44 years with the Armada Peruana) to become a museum ship.

In August 1976 De Zeven Provinciën was renamed Aguirre. RIM-2 Terrier SAM removed, replaced by a hangar with large flight deck for three ASH-3D Sea King helicopters. Decommissioned 1999.

In 1964 new plans were developed concerning the structure of the fleet within the first six years of the seventies. The intention was to decommission the carrier and replace the cruisers by two or four guided missile frigates. They would be equipped with an automated force AAW weapon-system TARTAR. Their coordination system consisting of the 3D radar and an automatic Combat Information Processing and Distribution System (DAISY) with automated inter-ship data-links. In October 1970 an order was placed with KM De Schelde in Vlissingen (Flushing) for the delivery of two GM-frigates.

Short response time became necessary. The new threat required changes in the build up of the fleet and its armaments. A decision had to be taken to modernize or replace the large ships of the fleet, the latter being chosen for cost reasons. Technological developments also played a role. In the new design automation was saving space. The development of gas turbines for propulsion was one of these. It resulted in a personnel reduction. Gas turbines were immediately operational and increased readiness (not raising steam). The machinery was remote controlled. The development of a 3D radar in combination with an automatic combat information system (DAISY) was another innovation that appealed to the Royal Netherlands Navy. With the 3D radar, it became possible to establish, besides bearing and distance, also the altitude of incoming objects in the air and report these contacts to fire control (WM-25).

In Chapter 2 we showed that flow disturbances can be decomposed into vorticity, entropy, and dilatational/acoustic fluctuations. The next two chapters focus on the evolution of vorticity in flows, and how vorticity in one region of the flow interacts with other regions of vorticity to influence hydrodynamic flow stability, leading to self-organization into concentrated regions of vorticity and flow rotation. Such large-scale structures, embedded on a background of acoustic waves and broadband, smaller-scale turbulence, dominate the unsteady flow fields in combustors. These large-scale structures play important roles in processes such as combustion instabilities, mixing and entrainment, flashback, and blowoff. For example, we will discuss vortex–flame interactions repeatedly in discussions of combustion instabilities in later chapters.

This book is about unsteady combusting flows, with a particular emphasis on the system dynamics that occur at the intersection of the combustion, fluid mechanics, and acoustic disciplines – i.e., on combustor physics. In other words, this is not a combustion book – rather, it treats the interactions of flames with unsteady flow processes that control the behavior of combustor systems. While numerous topics in reactive flow dynamics are “unsteady” (e.g., internal combustion engines, detonations, flame flickering in buoyancy-dominated flows, thermoacoustic instabilities), this text specifically focuses on unsteady combustor issues in high Reynolds number, gas-phase flows. This book is written for individuals with a background in fluid mechanics and combustion (it does not presuppose a background in acoustics), and is organized to synthesize these fields into a coherent understanding of the intrinsically unsteady processes in combustors.

This chapter presents the key equations for a multicomponent, chemically reacting perfect gas which will be used in this text [1]. These equations describe the thermodynamic relationships between state variables in a perfect gas, such as the interrelationship between pressure, density, and entropy. They also describe the physical laws of conservation of mass, which relates the density and velocity, the momentum equation, which relates the velocity and pressure, and the energy equation, which relates the internal and kinetic energy of the flow to work and heat transfer to the fluid.

Chapter 11 described the dynamics of flamelets forced by velocity or burning rate oscillations and illustrated the key physics controlling the spatiotemporal dynamics of the flame position. This chapter focuses on the impacts of these disturbances on the mass burning rate and/or heat release rate itself. For example, a key quantity of interest for the thermoacoustic instability problem is the heat release fluctuations that are induced by the flame disturbances. Section 12.1 gives an overview of the basic mechanisms through which flow disturbances lead to heat release oscillations, and differentiates between velocity coupling, fuel/air ratio coupling, pressure coupling, and acceleration coupling. Section 12.2 treats the effects of the flame configuration on its sensitivity to these disturbances, such as geometry or reactant premixing.

This chapter describes the processes associated with spontaneous (or “autoignition”) and forced ignition. The forced ignition problem is of significant interest in most combustors, as an external ignition source is almost always needed to initiate reaction. Two examples where the autoignition problem is relevant for flowing systems are illustrated in Figure 8.1 [1–10]. Figure 8.1(a) depicts the autoignition of high-temperature premixed reactants in a premixing duct. This is generally undesirable and an important design consideration in premixer design. Figure 8.1(b) depicts the ignition of a jet of premixed reactants by recirculating hot products. In this case, autoignition plays an important role in flame stabilization and the operational space over which combustion can be sustained. Although not shown, autoignition can also occur during the injection of a fuel, air, or premixed reactants jet into a stream of hot fuel, air, or products. For example, a vitiated H2/CO stream reacts with a cross-flow air jet in RQL combustors [11].