An advanced theory of thin-walled girders with application to ship vibrations

The paper presents an outline of the advanced theory of thin-walled girders. The improvement includes shear influence on torsion as an extension of shear influence on bending. The analogy between bending and torsion is recognized and pointed out throughout the paper. Complete differential equations of coupled flexural and torsional vibrations for a prismatic girder are derived. In addition, the 8 d.o.f. beam finite element, utilizing the energy approach, is constituted with stiffness and mass matrices, and load vectors. The paper describes determining of geometrical properties of multi-cell open cross-sections by employing the strip element method. Numerical procedures for vibration analyses are outlined. Furthermore, dry natural vibrations of a VLCS (Very Large Container Ship) are analysed by 1D FEM model as a prerogative for hydroelastic analyses of these relatively flexible vessels. Influence of transverse bulkheads is taken into account by increasing torsional stiffness of the ship hull proportionally to their deformation energies. Validation of 1D FEM model is checked by correlation analysis with the vibration response of the fine 3D FEM model.     

高速公路地质雷达探测溶洞成果精度提高方法的探讨

地质雷达(GPR)作为近期发展起来的一种新的地球物理勘探手段，与其他物探仪器相比，具有分辨率高，勘探成本低，速度快等优点，已在高速公路建设中得到广泛应用，但其探测路基下溶洞的精度还有待提高。结合湖南省某高速公路工程的物探与补充钻探资料，详细分析了导致两者存在差异的原因。通过应用现代统计原理，发现两者之间存在线性相关关系，并得到了关系式。为提高地质雷达探测路基下空洞的精度提供了新的途径。     

Determining the number and location of winter road maintenance depots – a case study of the district road network in Serbia

Determining the number and location of depots for winter road maintenance (WRM) represents one of the important strategic decisions while planning WRM activities. However, most organizations dealing with WRM make empirically based decisions. Optimizing the number and location of WRM depots has the potential to achieve considerable cost savings, improve mobility and efficiency, as well as reduce environmental impacts. This paper presents two optimization models. The first model determines the location of WRM depots by minimizing the total distance travelled by maintenance vehicles. The second model determines the optimum number and location of WRM depots by minimizing total transportation costs and capital expenditure and operational expenditure of the depots. The models are then applied to the district road network in Serbia. Results show that their application could lead to significant reductions in WRM costs.     

Revenue management in the parking industry: a multiple garage intelligent reservation model

This paper explores how advanced reservations, coupled with dynamic pricing (based on booking limits) can be used to maximize parking revenue. An integer programing formulation that maximizes parking revenue over a system of garages is presented. Furthermore, an intelligent parking reservation model is developed that uses an artificial neural network procedure for online reservation decision-making. Finally, the paper provides some strategic and managerial implications of multi-garage revenue management systems, and discusses techniques for identifying and implementing micro-market segmentation in the parking industry.     

Risk pricing inefficiency in public–private partnerships*

There is a drive towards delivering and operating public infrastructure through public–private partnership (PPP) rather than traditional public procurement. The assessment of the value for money achieved by the two alternative approaches rests in the cost of financing and their efficiency in delivery and operation. This paper focuses on the cost of financing, in particular the cost associated with transferring risk from the public to private sphere. If capital markets were efficient and complete, the cost of public (government) and private financing should be the same, with the relative delivery and operational efficiency remaining as the primary determinant of value-for-money. Evidence suggests, however, that the risk transfer to a PPP entails an inefficient risk pricing premium which goes beyond the direct cost of financing. We argue that a high price for PPPs results from large risk transfers, risk treatment within the private sector, and uncertainty around the past and future performance of public–private consortia. The corollary is that the efficiency gains from a PPP must be much higher than commonly expected to deliver a greater value for the money than under a traditional approach.     

Optimisation of active suspension control inputs for improved performance of active safety systems

A collocation-type control variable optimisation method is used to investigate the extent to which the fully active suspension (FAS) can be applied to improve the vehicle electronic stability control (ESC) performance and reduce the braking distance. First, the optimisation approach is applied to the scenario of vehicle stabilisation during the sine-with-dwell manoeuvre. The results are used to provide insights into different FAS control mechanisms for vehicle performance improvements related to responsiveness and yaw rate error reduction indices. The FAS control performance is compared to performances of the standard ESC system, optimal active brake system and combined FAS and ESC configuration. Second, the optimisation approach is employed to the task of FAS-based braking distance reduction for straight-line vehicle motion. Here, the scenarios of uniform and longitudinally or laterally non-uniform tyre–road friction coefficient are considered. The influences of limited anti-lock braking system (ABS) actuator bandwidth and limit-cycle ABS behaviour are also analysed. The optimisation results indicate that the FAS can provide competitive stabilisation performance and improved agility when compared to the ESC system, and that it can reduce the braking distance by up to 5% for distinctively non-uniform friction conditions.     

External costs from vessel emissions at port: a review of the methodological and empirical state of the art†

The accurate calculation of external costs from vessel emissions and shipping (as it happens with transport) strongly depends on parameters such as location, the time of the day and vessel operative. Thus, the use of a full bottom-up approach and granular traffic details is suggested. The latter may represent a substantial improvement in the resolution of shipping activity, energy demand, emissions and cost data being the latter essential for better regulations. The revised work identifies the Impact Pathway Approach (IPA) as the best-practice bottom-up methodology for calculating site-specific external costs derived from shipping air emissions. It has been widely adopted, among others, over major European studies (CAFE, BeTa, NEEDS and HEATCO). Also, it shows that due to costly and complex requirements of creating a shipping and harbour-specific bottom-up approach, external cost calculation based on tonne per euro factors obtained from European Studies (top-down approach) has been widely accepted. Moreover, methodological improvements and the possible achievement of refined estimations (IPA) dedicated to ports and shipping are strongly suggested, as these may improve information quality used for environmental policy and measures that contribute to the internalisation of externality costs.     

Hydroelasticity of large container ships

The importance of hydroelastic analysis of large and flexible container ships of today is pointed out for structure design. A methodology for investigation of this challenging phenomenon is drawn up and a mathematical model is worked out. It includes the definition of ship geometry, mass parameters, structure stiffness, and combines ship hydrostatics, hydrodynamics, wave load, ship motion and vibrations. The modal superposition method is employed. Based on the presented theory, a computer program is developed and applied for hydroelastic analysis of a large container ship. The transfer functions for heave, pitch, roll, vertical and horizontal bending and torsion are presented. Rigid body and elastic responses are correlated.     

汽车动力传动系统的换挡品质控制

介绍了汽车动力传动系统的换挡品质控制。详细介绍了换挡品质控制的主油压控制、发动机断油控制方法。最后给出了换挡品质控制试验结果。从试验结果可以看出，换挡品质控制措施是有效的。     

浅析既有线计算机联锁改造方案

以某TYJL-Ⅱ型既有计算机联锁车站站改临时过渡为例,对既有线计算机联锁3种改造方案进行分析比对,提出根据实际情况采用不同的设计方案使工程投资、施工工作量、风险度最小化。