Alternate route to soliton solutions in hydrogen-bonded chains

In this paper we offer an alternate route for investigating soliton solutions in hydrogen-bonded chains. This is done by examining a class of systems of two coupled real scalar fields. We show that this route allows investigating several models for hydrogen-bonded chains in a unified manner. We also show how to investigate interesting issues, in particular the one concerning classical or linear stability of solitonic solutions.Comment: 12 pages. Late

A Story of Consistency: Bridging the Gap between Bentham and Rawls Foundations

The axiomatic foundations of Bentham and Rawls solutions are discussed within the broader domain of cardinal preferences. It is unveiled that both solution concepts share all four of the following axioms: Nonemptiness, Anonymity, Unanimity, and Continuity. In order to fully characterize the Bentham and Rawls solutions, three variations of a consistency criterion are introduced and their compatibility with the other axioms is assessed. Each expression of consistency can be interpreted as a property of decision-making in uncertain environments

Neural Network Based Vibration Control of Seismically Excited Civil Structures

This study proposes a neural network based vibration control system designed to attenuate structural vibrations induced by an earthquake. Classical feedback control algorithms are susceptible to parameter changes. For structures with uncertain parameters they can even cause instability problems. The proposed neural network based control system can identify the structural properties of the system and avoids the above mentioned problems. In the present study it is assumed that a full state of the structure is known, which means the at each floor horizontal displacements and rotations about the vertical axis are measured. Additionally, it is assumed the acceleration signal coming from the earthquake is also available. The proposed neural control strategy is compared with the classical linear quadratic regulator (LQR) not only in terms of displacement responses, but also required control forces. Moreover, the influence of different weighting matrices on performance of the proposed control strategy has been presented.The effectiveness of the neuro-controller has been demonstrated on two numerical examples: a simple single degree of freedom (DOF) structure and a multi-DOF structure representing a twelve story building. Both structures under consideration have been excited with El Centro acceleration signal. The results of numerical simulations on the SDOF system indicate that using neuro-controller it would be possible to obtain smaller amplitudes as compared with the LQ regulator, but it would require higher control effort

The Cost of Retrofitting Steel-Concrete Composite Buildings Against Progressive Collapse with Steel Cables

Steel cables are an attractive means of retrofit with various engineering applications. They have been extensively used to strengthen deficient buildings against gravitational or earthquake-induced loads. This work investigates the use of steel cables as a means of retrofitting steel-concrete composite buildings against progressive collapse. The effect of the building’s characteristics on the total retrofit cost is studied. A fair assessment of designs defined for different requirements is achieved by definition of the most cost-effective solution for each scenario. This is achieved by an optimization algorithm, i.e. the Evolution Strategies, which is employed to define the solution with the desired performance and, at the same time, the minimum cost. For this purpose, a total number of 144 optimizations have been performed. The results yielded reveal the different properties of each retrofit scenario

The effect of rotational component of earthquake excitation on the response of steel structures

This work is on the influence of the rotational component of earthquake excitations to the response of steel structures. In most studies, seismic input is being modeled only using the translational component of the ground acceleration, while the rotational one is ignored. This was due to the observation that the rotational component had minimal effect on low-rise buildings. Hence, the accelerometers used would not measure it, leading to a lack of records. Nowadays, technology provides such instruments and relative records are made available. Indicative of that is that elastic design response spectra for rotational components are introduced to the design codes. In this paper, the results on structural response and internal forces due to the rotational component of a seismic excitation on the steel structures are examined. Dynamic time history analysis and response spectrum analysis of different steel structures are performed (a) considering the rotational component of the excitation and (b) without it. From the numerical results it is shown that the impact of rotational component in structural response and internal forces of the steel structures is significant and should not be ignored during structural design