Terminal Gate Research Articles

A comparison of semi-trailer transport of international maritime container cargo in Japan and South Korea, and its implications

This paper clarifies the current flow of semi-trailers with international maritime container cargo in Japan, focusing on time distribution and expressway utilisation, by an investigation in the Tokyo Metropolitan Area as well as in port districts. For comparison, a similar survey was also conducted in the urban and port area of Busan, South Korea. Based on the results, the commonalities and differences between both countries are examined. Implications for Japanese transport conditions of semi-trailers are discussed, especially in terms of container terminal gate open times, transporting two 20ft containers loads, usage of inland depots, and promotion of their expressway use.

Container terminal gate appointment system optimization

As a consequence of continuing growth of container volume and the introduction of 12 000 TEU plus containerships into major trade routes, the port industry is under pressure to come up with the necessary capacity to accommodate the increasing freight volume. One critical issue is the marine terminal gate capacity. Limited gate capacity leads to congestion. The harbor trucking industry operates in a very competitive environment; gate congestion is detrimental to their economic well-being. This article applies a multi-server queuing model to analyze marine terminal gate congestion and quantify truck waiting cost. An optimization model is developed to balance the gate operating cost and trucker’s cost associated with excessive waiting time. The model is tested using data from field observations. A case study is applied to analyze gate congestion behavior and truck waiting cost. Model sensitivity is discussed. The results indicate that truck waiting cost at marine terminal gates is an issue that needs to be addressed. A truck appointment system seems to be the most viable way to reduce gate congestion and increase system efficiency. With an optimized appointment system, the total system costs, especially truck waiting cost, can be drastically reduced.

The Clean Trucks Program: Evaluation of Policy Impacts on Marine Terminal Operations

The Clean Trucks Program is a Clean Air Action Plan initiative currently being adopted by the Ports of Los Angeles and Long Beach. This paper examines each of the Clean Trucks Program’s current requirements and estimates the impact on terminal operations. Using terminal operations data supplied by three terminal operating companies, we conduct a simple queuing analysis and present a regression model which allow us to consider the potential impact of the policy changes. While the impact at a specific terminal is not estimated in this paper, we consider order of magnitude effects. While the programme itself does not require terminal operations changes, the programme will modestly increase incentives to improve operational efficiency outside the terminal and reduce terminal gate processing time. It will also require technology that could be used for further operational changes. We show, however, that unless gate time improvements are matched with these operational improvements in the terminal, they will only move the delay inside the terminal and not reduce total terminal time. Our research considers the impact of the Clean Trucks Program on the Ports of Los Angeles and Long Beach, but similar concerns are driving changes at ports around the globe. Maritime Economics & Logistics (2008) 10, 393–408.

Controlled electronic transport through branched molecular conductors

The conductance through a branched conductor placed between two electrodes is analyzed using the Landauer transport formulation within the framework of the single electron, and the tight binding approximations. Terminal side chains are expressed as self energy terms which map the branched conductor onto an effective linear chain Hamiltonian. The effect of uniform side branches on resonant zero-bias conductance is shown to be analytically solvable and particularly simple, where subtraction or addition of a single terminal site can induce an effective discontinuity in the main linear chain or can effectively decouple the side branch from the conductor. Manipulating the “effective length” of a side branch by a local terminal gate potential, control of the small bias current through the branched conductor is demonstrated.

A Simulation Study on the Efficiency of RFID at Container Terminal Gate System

A container terminal gate is not only an entrance of containers, but also the first input point of containers' information. Therefore, to achieve the accuracy of container information, there are various containers' numbers recognition methods used. Gate productivity can significantly vary depending upon those recognition methods. Recently, RFID which is one of the u-IT businesses run by the Korean government is under consideration for application to the gate as an automatic system. If RFID is used, it is expected to have both the qualitative benefits through avoiding defects of other systems and the quantitative benefits by improving productivity. Hence, this study aims to provide some insight on the benefits of RFID, and to compare productivity of the existing gate system with the RFID gate system based on computer simulation.

Reducing port-related truck emissions: The terminal gate appointment system at the Ports of Los Angeles and Long Beach

Growth in international trade and changing patterns of production have resulted in greatly increased volumes of freight traffic in urban areas. Metropolitan areas serving as major nodes within the international trade network are particularly affected. In California, state regulation was imposed on port operations in an effort to mitigate congestion and air pollution associated with increased port-related trade. This paper presents an evaluation of the outcomes of California Assembly Bill (AB) 2650 at the Ports of Los Angeles and Long Beach. The legislation permitted terminals to adopt either gate appointments or off-peak operating hours as a means of reducing truck queues at gates. There is no evidence of reduced queuing or transaction times, and hence that AB 2650 did not result in reduced truck emissions.

A study on efficient gate system based RFID at the container terminal

It is a world trend to construct large terminal and develop automated container terminal to attract Super Post-Panamax and provide service which is based on differentiation. In fact, there is insufficient research for automatization of terminal gate since the automatization of current constructed container terminal is only focused on increasing productivity and unmanned system through the automatization of quay, yard, etc. In this paper, we have investigated advantage/disadvantage of existing gate operation systems and compared each gate operation system in the aspect of raising terminal image and the productivity. For the specific study, we have used data from actual terminal gate operation and RFID model business sponsored by MOMAF (Ministry of Maritime Affairs and Fisheries). As a result, this paper carried out an efficient gate operation system and it has been expected that it will be performed as groundwork of automated gate operation system which is for design of container terminal and improvement of gate operation system.

The benzene molecule as a molecular resonant-tunneling transistor

Experiments and theory have so far demonstrated that single molecules can form the core of a two-terminal device. Here we report first-principles calculations of transport through a benzene-1, 4-dithiolate molecule with a third capacitive terminal (gate). We find that the resistance of the molecule rises from its zero-gate-bias value to a value roughly equal to the quantum of resistance (12.9 kΩ) when resonant tunneling through the π* antibonding orbitals occurs.

Transport Calculations in Molecular Devices from First Principles

ABSTRACTFor molecular electronics, Boltzmann's equation is no longer valid for simulating device characteristics. We resent the first fully ab initio simulation of a molecular device that has already been studied ex erimentally, namely a benzene-1,4-dithiolate molecule between gold electrodes. The theoretical I-V curve has the same overall sha e as the ex erimental curve —reflecting the electronic structure of the molecule in the resence of the electric field — but the absolute value of the current is very sensitive to contact chemistry and geometry. In articular the resence ol a single gold atom between the molecule and the electrode surface reduces the conductance by more than an order of magnitude. Re lacement of the single gold atom by an aluminum atom, whose p orbitals cou le more effectively to the molecule's T orbitals, increases the conductance by about an order of magnitude. We have also studied the olarization effects induced by a third terminal (gate) on the I-V characteristics of the above device. In articular, we have found that current gain due to the gate bias can be achieved at reasonable gate fields. Finally the effect of current-induced forces on the device will be discussed.

Source-drain burnout mechanism of GaAs power MESFETS: Three terminal effects

Theoretical expressions for thermal and electrical feedback effects are derived. These limit the power capability of a power FET and lead a device to catastrophic breakdown (source-drain burnout) when the loop gain of the former reaches unity. Field emission of thermally excited electrons at the Schottky gate plays the key role in thermal feedback, while holes being impact ionized by the drain current play a similar role in the electrical feedback. Thermal feedback is dominant in a high temperature and low drain voltage area. Electrical feedback is dominant in a high drain voltage and low temperature area. In the first area, a high junction temperature is the main factor causing the thermal runaway of the device. In the second area, the electrcal feedback increases the drain current and the temperature and gives a trigger to the thermal feedback so that it reaches unity more easily. Both effects become significant in proportion to transconductance and gate bias resistance, and cause simultaneous runaway of the gate and drain currents. The expressions of the loop gains clearly indicate the safe operating conditions for a power FET. C-band 4 W (1 chip) and 16 W (4 chip) GaAs MESFETs were used as the experimental samples. With these devices the simultaneous runaway of the gate and the drain currents, apparent dependence of the three teminal breakdown voltage on the gate bias resistance in the region dominated by electrical feedback, the rapid increase of the field emitted current at the critical temperature and clear coincidence between the measured and calculated three terminal gate currents both in the thermal feedback dominant region, etc. are demonstrated. The theory explains the experimental results well.

High Resistivity Oxygen-Doped AlGaAs For Power Devices

AbstractWe have succeeded in making high resistive AlxGa1−xAs by oxygen doping (AlxGa1−xAs:O) and applying them to buffer layer for power metal-semiconductor field effect transistor (MESFET). Samples of Al0.3Ga0.7As:O were prepared by metalorganic vapor phase epitaxy (MOVPE). Oxygen-related levels in A10.3Ga0.7As:O were investigated by applying isothermal capacitance transient spectroscopy (107S) to MIS (Al/Al0.3Ga0.7As:O/n-GaAs) diodes. A breakdown voltage and a two terminal gate breakdown voltage of the MESFET with the Al0.3Ga0.7As:O buffer layer became higher as increasing in the intensity of oxygen related peak in the ICTS spectra. These results indicate that the electrically active oxygen in the Al1−xGa1−xAs:O is an important factor for the device characteristics.

Automatic assignment of aircraft to gates at a terminal

The assignment of airplanes to terminal gates should take into account not only the physical constraints of the terminal, but also the incoveniences suffered by the transporter and the travellers when a craft has to be serviced away from the terminal. With this in mind, it is preferable that the number of airplanes assigned to a service area away from the terminal, rather than directly placed at a terminal gate, be minimized. Once this problem has been formulated in the form of a linear programming model with binary variables, a heuristic method is applied to find the best solution.

Avalanche ionization rates measured in silicon and germanium at low electric fields

Ionization rates in semiconductors can be measured at low values of electric field using a new method involving a field-effect transistor (FET) structure which offers greater sensitivity than reverse biased p-n junction diode methods. Carriers of only one polarity cause ionization in the FET and no correction is required for ionization caused by carriers of the opposite polarity. Since secondary carriers resulting from ionization are attracted to a different terminal (gate or substrate) than that used to collect the primary carriers (drain), very small ionization currents can be detected. Values of electron ionization rate α n and hole ionization rate α p as low as 10-3cm-1have been obtained for silicon. The approximate relationship \alpha = \alpha_{\infin}e^{-b/E} is observed and the values of α at high fields correspond to those obtained conventionally. Values of α p from 0.04-1to 0.4 cm-1have been obtained for germanium. Analytical determination of electric field was provided by a solution of Poisson's equation for the field-effect structure. Difficulty in accurately determining the FET channel doping introduces a ± 30 percent uncertainty in electric field values. The method is applicable to any semiconductor material where junction, MOS, or Schottky barrier techniques can be used to construct field-effect transistors.