Stochastic cell transmission model (SCTM): A stochastic dynamic traffic model for traffic state surveillance and assignment

The paper proposes a first-order macroscopic stochastic dynamic traffic model, namely the stochastic cell transmission model (SCTM), to model traffic flow density on freeway segments with stochastic demand and supply. The SCTM consists of five operational modes corresponding to different congestion levels of the freeway segment. Each mode is formulated as a discrete time bilinear stochastic system. A set of probabilistic conditions is proposed to characterize the probability of occurrence of each mode. The overall effect of the five modes is estimated by the joint traffic density which is derived from the theory of finite mixture distribution. The SCTM captures not only the mean and standard deviation (SD) of density of the traffic flow, but also the propagation of SD over time and space. The SCTM is tested with a hypothetical freeway corridor simulation and an empirical study. The simulation results are compared against the means and SDs of traffic densities obtained from the Monte Carlo Simulation (MCS) of the modified cell transmission model (MCTM). An approximately two-miles freeway segment of Interstate 210 West (I-210W) in Los Ageles, Southern California, is chosen for the empirical study. Traffic data is obtained from the Performance Measurement System (PeMS). The stochastic parameters of the SCTM are calibrated against the flow-density empirical data of I-210W. Both the SCTM and the MCS of the MCTM are tested. A discussion of the computational efficiency and the accuracy issues of the two methods is provided based on the empirical results. Both the numerical simulation results and the empirical results confirm that the SCTM is capable of accurately estimating the means and SDs of the freeway densities as compared to the MCS.     

Solution for failure analysis of automotive axle knuckle pull-out

A completely safe engineering solution to the automotive assembly line knuckle ball-joint pull-out problem is achieved using failure analysis based on the “Design of Experiment” (DOE) method. During use, some ball-joints move in their housings or come loose under heavy loads. The purpose of this study is to determine critical production parameters that will eliminate this failure. In this research, the knuckle-ball-joint pull-out problem is examined, and knuckle housing and ball-joint outer diameter limits are re-defined. Four levels of interference between knuckle and ball-joint diameters and 2 levels of knuckle thickness are specified. Experiments are repeated five times using General Variance Analysis. Required pull-out force is determined, and necessary interference is found. New knuckle housing and ball-joint diameters, based on recommended interference values, are determined. It is also found that thickness of knuckle boss does not affect the results. Therefore, the design is unchanged in this region and this reduces costs.     

Synoptic transects on the distribution of trace elements (Hg,Pb, Cd,Cu, Ni,Zn, Co,Mn, Fe,and Al) in surface waters of the Northern- and Southern East Atlantic

Surface seawater samples were taken in the framework of the GEOTRACES program on “POLARSTERN” expedition ANT XXIII/1 in the Eastern Atlantic in 2005 to study the distribution of the trace elements Hg (mercury), Pb (lead), Cd (cadmium), Cu (copper), Ni (nickel), Zn (zinc), Co (cobalt), Mn (manganese), Fe (iron), and Al (aluminium). With the exception of Hg, results were compared to earlier datasets from 1989 to 1990. The particulate fraction averaged over the transect was calculated to be 49% for Cd, 23% for Mn and 50% for Fe indicating a release of these TEI's (trace elements and their isotopes) from a leachable SPM fraction in the stored and acidified samples.Total Pb concentrations ranged between 5 and 20 pmol kg^? 1 in 2005 with highest values in the ITCZ (intertropical convergence zone). In 1989 Pb concentrations were twice as high in the region of the ITCZ, while by a factor of 10–15 higher values were obtained in the North Atlantic.Total Cd and Co are dominated, by different seasonal upwelling regimes (Equatorial upwelling, Guinea Dome, Angola Dome).Total Cu, Ni, Fe, Mn and Al show nearly identical concentrations in 1990 and 2005. For total manganese and aluminium strong maxima (3–4 nmol kg^? 1 and 55 nmol kg^? 1 respectively) are observed between 23°N and 0°, while the Fe maximum (6–9 nmol kg^? 1) is located at 7°N. Total Hg concentrations ranged between 0.5 and 4.5 pmol kg^? 1.     

Telemetric system for monitoring and automation of railroad networks

This paper describes a new method of real-time train monitoring based on the ZigBee/IEEE 802.15.4 protocol. The system consists of a mobile device embedded in the moving train which transmits parameter signals that are being measured by a base unit with the help of routers. When applied, the technique monitors and controls vehicles operating on permanent routes, making a real-time evaluation of their performance and location, and allowing an effective planning of trains. It consists of a low cost, low power consumption and safe modular technology capable of monitoring many different variables simultaneously.     

Transportation survey and rideshare matching model for rural communities

A simple and flexible low technology rideshare matching model was developed for a rural area. A brief survey form provided information on distance to work, fuel consumption and currently used transportation mode in conj unction with information on employment location and work schedule. The model developed used a computerized system for proximity matching of potential ride sharers. An existing computer program with detailed modifications was used for data analysis. Unlike other rideshare matching programs, this model relies on grouping by community names to match riders.     

Airport system planning—a U.K. study

There is growing public pressure, from environmentalist groups and others, for the imposition of lorry bans in urban areas. In the U.K. such bans have so far only been imposed as through‐route bans by small towns, such as Windsor, where the overall impact on operators and on road freight costs is limited. The Greater London Council's response to the pressure for lorry bans has been to set up a Committee of Inquiry to examine the impact of an access ban on the heaviest lorries in the London area. The proposed ban would apply to an area enclosed by the M25 orbital motorway within which vehicles above a specified gross tonnage would not be allowed to operate. A number of metropolitan authorities elsewhere in the U.K. are thought to be considering similar restrictions on lorries.

In this paper, the impact of area lorry bans on goods vehicle operating costs is discussed. It is suggested that practices based on “direct distribution” techniques may prove less costly than the operating alternatives that have been evaluated in the past which include public transhipment depots and the exclusive use of small vehicles.     

Positive impact of distribution centres on the environment

The transport sector in general, and trucks in particular, generates a significant amount of emissions in Australia. It appears the trend will escalate unless different measures are taken to reduce the reliance of freight transport on trucks. This paper discusses the benefits of distribution centres as a means to reduce road congestion, increase safety, protect the environment by reducing atmospheric pollution and improve freight distribution. It also provides the effective use of the existing rail network and its infrastructure and improves the lead-time as well as lowering the cost of transportation of cargo. It also investigates the positive impact of distribution centres located near to manufacturing and farming production units. A simulation model has been developed and used to help determine the amount of atmospheric pollution produced by two modes of land transport, rail and road, for the movement of containers between port and destination. Results derived from the model provide evidence about a preferred land-transport regime. The paper has two sections: (1) the role of distribution centres in the chain of transport and (2) the impact of distribution centres on the environment. The first section investigates the feasibility of the implementation of distribution centres in the State of Victoria with respect to rail line capacity and location allocation. The second section presents an additional simulation model that investigates the role of a distribution centre in relation to the amount of atmospheric pollution produced by rail and road, while containers are carried between port and destination.     

Probability distributions of wave run-up on a TLP model

Wave run-up on multi-column compliant and rigid platforms both on the weather-side and beneath the platform deck is a complex wave–structure interaction problem. Predictions based upon higher order hydrodynamic design codes have been improved our understanding of this phenomena but have not appreciably reduced the reliance on model tests and statistical analyses. In this study a three parameter distribution model is developed based upon the inclusion of linear, second-order, and mean contributions to the wave run-up utilizing the method of L-moments. Explicit expressions are derived relating the L-moments and the input from experimental data. The sample L-moments are developed from a linear combination of ordered sequence of the data and consequently the high order L-moments, i.e. L-skewness and L-kurtosis, are less biased than the corresponding ordinary moments. The L-moment definitions of the variance, skewness and kurtosis are numerically compared with values obtained using the more standard definitions for these parameters. Rigid hull measurements are compared with the compliant hull configuration for a mini-TLP model. The sea-states investigated include the relatively benign sea conditions off of West Africa and the more extreme sea environments of Gulf of Mexico.     

Experimental study and 3D CFD analysis on the optimization of throttle angle for a convergent vortex tube

Seven adjustments of convergent-type Vortex Tube (VT) with different throttle angles were applied. The adjustments were made to analyze the influences of such angles on cold and hot temperature drops as well as flow structures inside the VTs. An experimental setup was designed, and tests were performed on different convergent VT configurations at injection pressures ranging from 0.45 to 0.65 MPa. The angles of the throttle valve were arranged between 30° to 90°, and the numbers of injection nozzles ranged between 2 and 6. Laboratory results indicated that the maximum hot and cold temperature drops ranged from 23.24 to 35 K and from 22.87 to 32.88 K, respectively, at four injection nozzles. Results also showed that temperature drop is a function of hot throttle valve angle with the maximum hot and cold temperature drops depending on the angle applied. We used graphs to demonstrate the changes in the cold and hot temperature drops with respect to hot throttle angle values. These values were interpreted and evaluated to determine the optimum angle, which was 60°. The CFD outputs agreed very well with the laboratory results. The proposed CFD results can help future researchers gain good insights into the complicated separation process taking place inside the VTs.