Ideal Drift Response Curve for Robust Optimal Damper Design for Elastic-Plastic MDOF Structures under Multi-Level Earthquakes Dedicated to Professor Karl S.Pister for his 95th birthday

A new method of robust damper design is presented for elastic-plastic multi-degree-of-freedom(MDOF)building structures under multi-level ground motions(GMs).This method realizes a design that is effective for various levels of GMs.The robustness of a design is measured by an incremental dynamic analysis(IDA)curve and an ideal drift response curve(IDRC).The IDRC is a plot of the optimized maximum deformation under a constraint on the total damper quantity vs.the design level of the GMs.The total damper quantity corresponds to the total cost of the added dampers.First,a problem of generation of IDRCs is stated.Then,its solution algorithm,which consists of the sensitivity-based algorithm(SBA)and a local search method,is proposed.In the application of the SBA,the passive added dampers are removed sequentially under the specified-level GMs.On the other hand,the proposed local search method can search the optimal solutions for a constant total damper quantity under GMs’increased levels.In this way,combining these two algorithms enables the comprehensive search of the optimal solutions for various conditions of the status of the GMs and the total damper quantity.The influence of selecting the type of added dampers(oil,hysteretic,and so on)and the selection of the input GMs on the IDRCs are investigated.Finally,a robust optimal design problem is formulated,and a simple local search-based algorithm is proposed.A simple index using the IDRC and the IDA curve of the model is used as the objective function.It is demonstrated that the proposed algorithm works well in spite of its simplicity.

Overdoped High Current Density Bi2-xPbxSr2CaCu2O8＋δ Intrinsic Josephson Junction Mesas and Their Switching Current Distributions

Small and thin mesa structures of intrinsic Josephson junctions 1- 2μm on a side and 1.5-7.5 nm in thickness are fabricated from single crystals of Bi2-xPbxSr2CaCu2O8＋δ with a nominal Pb content x from 0.2 to 0.5. The Josephson critical current density jc is found to be pronouncedly large, ranging from 10 to 50 kA/cm^2. Switching current probability measurements for these mesa samples show an indication of a crossover to the macroscopic quantum tunneling region.

Preliminary report of the 2011 off the Pacific coast of Tohoku Earthquake

On March 11, 2011, eastern Japan was shaken by the 2011 off the Pacific coast of Tohoku Earthquake (the Great East Japan Earthquake). Almost 30 000 people have been killed or are missing as a result of that earthquake and the subsequent monster tsunami, as of April 11, 2011. This paper reports several aspects of this devastating earthquake. It has been reported that long-period ground motions, which had been predicted by many researchers, occurred in Tokyo, Nagoya and Osaka. The response characteristics of high-rise buildings to the recorded long-period ground motions are discussed from the viewpoint of resonance and critical excitation. It is shown that high-hardness rubber dampers are very effective in the reduction of vibration duration in addition to the reduction in vibration amplitude.

Crystal orientation-dependent fatigue characteristics in micrometer-sized single-crystal silicon

Repetitive bending fatigue tests were performed using five types of single-crystal silicon specimens with different crystal orientations fabricated from{100}and{110}wafers.Fatigue lifetimes in a wide range between 100 and 1010 were obtained using fan-shaped resonator test devices.Fracture surface observation via scanning electron microscope(SEM)revealed that the{111}plane was the primary fracture plane.The crack propagation exponent n was estimated to be 27,which was independent of the crystal orientation and dopant concentration;however,it was dependent on the surface conditions of the etched sidewall.The fatigue strengths relative to the deflection angle were orientation dependent,and the ratios of the factors obtained ranged from 0.86 to 1.25.The strength factors were compared with those obtained from finite element method stress analyses.The calculated stress distributions showed strong orientation dependence,which was well-explained by the elastic anisotropy.The comparison of the strength factors suggested that the first principal stress was a good criterion for fatigue fracture.We include comparisons with specimens tested in our previous report and address the tensile strength,initial crack length,volume effect,and effects of surface roughness such as scallops.

Approximate Solutions to the Hamilton-Jacobi Equations for Generating Functions

For a nonlinear finite time optimal control problem,a systematic numerical algorithm to solve the Hamilton-Jacobi equation for a generating function is proposed in this paper.This algorithm allows one to obtain the Taylor series expansion of the generating function up to any prescribed order by solving a sequence of first order ordinary differential equations recursively.Furthermore,the coefficients of the Taylor series expansion of the generating function can be computed exactly under a certain technical condition.Once a generating function is found,it can be used to generate a family of optimal control for different boundary conditions.Since the generating function is computed off-line,the on-demand computational effort for different boundary conditions decreases a lot compared with the conventional method.It is useful to online optimal trajectory generation problems.Numerical examples illustrate the effectiveness of the proposed algorithm.

Wave Propagation Simulation Using the CIP Method of Characteristic Equations

We apply the CIP(Cubic Interpolated Profile)scheme to the numerical sim-ulation of the acoustic wave propagation based on characteristic equations.The CIP scheme is based on a concept that both the wavefield and its spatial deriv ative propa-gate along the same characteristic curves derived from a hyperbolic differential equa-tion.We describe the derivation of the characteristic equations for the acoustic waves from the basic equations by means of the directional splitting and the diagonaliza-tion of the coffcient matrix,and establish geophysical boundary conditions.Since the CIP scheme calculates both the wavefield and its spatial derivatives,it is easy to realize the boundary conditions theretically.We also show some numerical simula-tion examples and the CIP can simulate acoustic w ave propagation with high stability and less numerical dispersion.The method of characteristics with the CIP scheme is a very powerful technique to deal w ith the wave propagation in complex geophysical problems.