Modelling forward freight rate dynamics—empirical evidence from time charter rates

The purpose of this paper is to investigate the dynamics of forward freight rate dynamics. We specify our model in a Heath–Jarrow–Morton framework. This model was originally developed for interest rate markets and, in subsequent work, the model has been applied to various commodity markets. We analyse ten years of weekly time charter (TC) rates for a Panamax 65,000?dwt bulk carrier. Our data set consists of 6-, 12- and 36-month TC rates. We use this data to construct, each day, a forward rate function using a smoothing algorithm. We use the smooth data to investigate the factors governing the dynamics of the forward freight rate curve. We find a strange volatility structure in the data. Out results show that the volatility of the forward curve is bumped, with volatility reaching a peak for freight rates with roughly one year to maturity. Also, correlations between different parts of the term structure are in general low and even negative.     

Coastal and Ocean Science-Based Decision-Making in the Gulf of California: Lessons and Opportunities for Improvement

The Gulf of California hosts astounding biodiversity that supports numerous economic activities in the region. These activities, and emerging threats, are placing pressure on the region's ecosystems. Government and civil society are working to address threats through several conservation and management mechanisms. Nevertheless, the use and incorporation of scientific information—a key component for creating effective and durable management—is still deficient. This article presents the concept of science integration and discusses the findings of a study that assesses the regional landscape, existing institutional arrangements, and capacity for using science to inform policy and management decisions. It also explores the current use of science within fisheries policy and management and the capacity of the National Network of Information and Research of Fisheries and Aquaculture (RENIIPA) and the State Fisheries and Aquaculture Councils, two mechanisms in the region. Finally, it shares lessons learned and offers recommendations on how the region can strengthen science-based decision-making. Results indicate that while there are some actors in the Gulf of California producing relevant science, there is varying capacity of intermediary groups connecting producers with users of science, or mechanisms in place to ensure that science is being utilized in decision-making processes. Moreover, despite having a well-developed landscape of producers and intermediaries and mechanisms in place for fisheries management in the region, effective science integration is not occurring.     

铁路货车运行品质考核指标研究

简要回顾了我国铁道车辆运行平稳性标准的应用历史和现状,指出其中存在的主要问题,以图寻求改进我国评价铁路货车运行平稳性指标的可行途径。介绍了AAR和UIC中的相应标准的概况;阐述了铁路货车运行平稳性方面的主要矛盾;分析了采用运行平稳性指标评价铁路货车运行品质的一些具体问题。建议增加评价车辆纵向运行平稳性的指标,以更全面地反映和评价车辆的动态运行品质。提出了货车运行平稳性评价体系调整过程中应开展的主要工作和改进我国铁路货车运行平稳性标准的方向。建议以车体加速度峰值和均方根值作为考核铁路货车运行平稳性的主要指标,同时建议修建专用的试验线或扩展现有的试验线,以便更加客观地考核、比较和研究车辆的动态性能。     

塑料排水板在深海地基加固中的应用

塑料排水板作为陆上软土地基加固处理方法,应用较广泛,如公路路基、港(厂)区基础等地基处理工程。但作为海上地基加固由于受施工船舶、风浪、潮流、水深等多种因素限制,施工难度大,施工质量不易控制,尤其是在水深7—10m打设深度超过30m外海施工中,难度更加大,工程实例不多。结合洋山深水港区二期水工码头工程A标段的施工,介绍塑料排水板在深海地基加固中的应用,供同行参考。     

Minimization of Pedaling Induced Energy Losses in Off-road Bicycle Rear Suspension Systems

This paper presents the results of an optimization analysis performed on off-road bicycles in which the energy loss induced as a result of pedaling action was minimized. A previously developed computer-based dynamic system model (Wang and Hull, Vehicle System Dynamics, 25:3, 1996) was used to evaluate the power dissipated by a single pivot point rear suspension while pedalling uphill on a smooth surface. By systematically varying the location of the pivot point, the relationship between power dissipated and pivot location was determined. The optimal location was defined as the location which resulted in the least power dissipated. The simulation results show that the power dissipated was very dependent on the height above the bottom bracket but not the fore-aft location of the pivot point. If the pivot point is constrained to the seat tube, then the optimal pivot point was found to be 11 cm above the bottom bracket. Compared to a commercially available design, the optimal pivot point reduced the power dissipated from 6.9 to 1.2 Watts. Furthermore, the optimal pivot point was found to be very insensitive to pedaling mechanics, and both the spring and damping parameter values. The optimal pivot point did, however, have a linear dependence on the height of the chainline; as the chainline height increased so too did the optimal pivot point height.     

Minimizing the Path Radius of Curvature for Collision Avoidance

When a driver is suddenly presented with an obstacle in his path, or realizes that his speed is too great for the curved road ahead, commonly he saturates both inputs of steering and braking and thereby jeopardizes his chances of successfully avoiding a collision or negotiating the turn. Although anti-lock braking systems (ABS) avoid saturation of the braking and steerability usually remains, there is evidence to suggest that the vehicle performance with this system could be greatly improved. Could the steering, in addition to the braking, be automatically controlled to improve the performance? Because these threatening situations are so variable, it is very difficult to find a controller which can override both driver inputs and is always beneficial. Using a very simple model of the vehicle, the concept of minimizing the average radius of curvature of the path through controlling both driver inputs is shown to always be beneficial, and worthwhile. The results also carry over to a more realistic model.     

变频技术在锅炉自动燃烧控制系统中的应用

变频技术是近年来应用范围广泛的一门技术，尤其在节约电能、自动控制等方面更为突出。变频技术应用在锅炉的燃烧控制中，既节约了电能，又使燃烧充分而节约了燃煤。由于改变了传统控制模式的运行方式，使锅炉自动燃烧控制系统运行更稳定，安全可靠。该系统应用于青岛四方机车车辆厂、山海关桥梁厂、齐齐哈尔车辆厂、南口机务段等单位，经测试效果明显，推广价值很大。     

Addressing the joint occurrence of self-selection and simultaneity biases in the estimation of program effects based on cross-sectional observational surveys: case study of travel behavior effects in carsharing

Transportation - We estimate the effect of carsharing on travel behavior (specifically, household vehicle holdings, frequency of transit usage, and frequency of biking and walking) using data from...     

Representing heterogeneity in structural relationships among multiple choice variables using a latent segmentation approach

Transportation - Travel model systems often adopt a single decision structure that links several activity-travel choices together. The single decision structure is then used to predict...     

Modeling schedule recovery processes in transit operations for bus arrival time prediction

Many existing algorithms for bus arrival time prediction assume that buses travel at free‐flow speed in the absence of congestion. As a result, delay incurred at one stop would propagate to downstream stops at the same magnitude. In reality, skilled bus operators often constantly adjust their speeds to keep their bus on schedule. This paper formulates a Markov chain model for bus arrival time prediction that explicitly captures the behavior of bus operators in actively pursuing schedule recovery. The model exhibits some desirable properties in capturing the schedule recovery process. It guarantees provision of the schedule information if the probability of recovering from the current schedule deviation is sufficiently high. The proposed model can be embedded into a transit arrival time estimation model for transit information systems that use both real‐time and schedule information. It also has the potential to be used as a decision support tool to determine when dynamic or static information should be used.