SUMMARYModal properties of tuned mass damper (TMDtstructure two-degree-of-freedom (2DOF) linear systems are studied employing a perturbation technique. Using the perturbation solutions, formulas relevant to designing the T M D for various types of loading are obtained; they are expressed as a function of mass ratio, tuning ratio, damping ratio of the T M D and damping ratio of the structure. Equivalent additional dampings of the structure due to the T M D are derived for random and harmonic forces. Matched expressions of equivalent damping, which are valid for detuned, i.e. non-optimal, conditions are also presented. The stability boundary of TMD-structure systems subject to linear self-excited forces is derived in a closed form. Using the perturbation solutions, procedures for optimizing the T M D parameters for various types of loading are explained and the optimal values are derived. The formulas obtained in this study can be used with good accuracy for mass ratios less than 0.02.

This paper presents a proposed optimum tire force distribution method in order to optimize tire usage and find out how the tires should share longitudinal and lateral forces to achieve a target vehicle response under the assumption that all four wheels can be independently steered, driven, and braked. The inputs to the optimization process are the driver’s commands (steering wheel angle, accelerator pedal pressure, and foot brake pressure), while the outputs are lateral and longitudinal forces on all four wheels. Lateral and longitudinal tire forces cannot be chosen arbitrarily, they have to satisfy certain specified equality constraints. The equality constraints are related to the required total longitudinal force, total lateral force, and total yaw moment. The total lateral force and total moment required are introduced using the model responses of side-slip angle and yaw rate while the total longitudinal force is computed according to driver’s command (traction or braking). A computer simulation of a closed-loop driver-vehicle system subjected to evasive lane change with braking is used to prove the significant effects of the proposed optimal tire force distribution method on improving the limit handling performance. The robustness of the vehicle motion with the proposed control against the coefficient of friction variation as well as the effect of steering wheel angle amplitude is discussed.

The non-destructive evaluation technique using a piezoceramic (PZT) as an actuator-sensor has a potential to efficiently detect structural damage. In this technique, a PZT actuator-sensor patch is bonded on a structure. Through the measurement of its electrical impedance, which is related to the mechanical impedance of the structure being bonded, the change in structural properties due to damage can be detected. This paper presents the use of a PZT actuator-sensor in conjunction with numerical model-based methodology in structural health monitoring to quantitatively detect damage of bolted joints. The structure used in this study consists of two aluminium beams connected by a bolted joint. The damage was simulated by loosening the bolts. To quantitatively monitor the damage, a numerical model of the structure was formulated. A spectral element method (SEM), based on a wave propagation approach, was used to model the structure. A bonded-PZT beam and a bolted joint element were developed by using the SEM. The equations of motion were derived by using Hamilton's principle and then the spectral element matrices were formulated. Experimental results show the effectiveness of this method to detect the damage. By using the proposed model, the loosening of bolts can be quantitatively identified as the change in stiffness and damping at the bolted joint, indicating a high potential of this method in order to quantitatively monitor structural damage.

SUMMARYUnseating of bridge girders=decks during earthquakes is very harmful to the safety and serviceability of bridges. Evidence from recent severe earthquakes indicates that in addition to damage along longitudinal direction, lateral displacement and rotation of bridge girders caused by pounding to adjacent girders can also lead to unseating. To simulate this e ect, 3D modelling of the dynamic performance of whole bridge structures, including pounding, is needed strongly. This paper presents a 3D model that is practically suitable to precisely analyse pounding between bridge girders. Experiments have been conducted to verify the proposed pounding model. The 3D non-linear modelling of steel elevated bridges is also discussed. A general-purpose dynamic analysis program for bridges, namely dynamic analysis of bridge systems (DABS) has been developed. Seismic analyses on a chosen three-span steel bridge are conducted for several cases including pounding as a case study. The applicability of the proposed pounding model is illustrated by the computations. The e ects of poundings on the response of bridge girders are discussed and the computation results are given.

Recent trends of vehicle chassis control are reviewed, paying attention to the basic nature of the vehicle dynamics, tyre characteristics and the effectiveness and limit of four-wheel steering (4WS) and direct yaw moment control (DYC). It is pointed out that, taking the non-linear characteristics of tyre and vehicle dynamics into consideration, change in chassis control from 4WS to DYC inevitably improves handling performance and active safety in vehicle motion with larger slip angles and/or higher lateral accelerations. Emphasis is placed on the need to propose a control strategy based on thorough observation and understanding of the tyre and vehicle dynamics. A side slip model following DYC by sliding control is introduced and the effects of the control are discussed.

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Purpose – The purpose of this paper is to propose policy suggestions for the financing of small and medium enterprises (SMEs) in the Asia-Pacific region. Recent literature suggests that lack of capital is the most severe constraint for SME survival and growth. Enabling policymakers to assist SMEs in their search for financing will boost economic growth. Design/methodology/approach – The methodology includes both quantitative and qualitative components. Current World Bank data on the strength of various financial institutions in the countries of interest is analyzed to discover areas of improvement. Additionally, 32 experts from East and South Asia were interviewed several times to determine areas of concern in financing SMEs. Their responses and the evidence from the World Bank data form the basis of the policy prescriptions in the paper. Findings – Financing is a critical constraint for SMEs for several reasons. Many SME owners do not manage working capital effectively, information asymmetry between banks and SMEs retards the loan application and approval process, and underdeveloped equity markets deny SMEs future growth opportunities. Policymakers can ameliorate conditions by serving as facilitators and communicators; governments should not provide financing directly if possible. Practical implications – It is hoped and expected that the policy prescriptions offered herein will enhance the growth and survival prospects of SMES, thereby creating more employment, innovation, and economic growth. Originality/value – The main contribution of this work is its scope. While the financing of SMEs is a familiar topic, the review of issues and policies in East and South Asia, and their distillation into practical advice for officialdom, is what makes this manuscript unique.

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