Containership Load Planning with Crane Operations

Since the start of the containerization revolution in 1950's, not only the TEU capacity of the vessels has been increasing constantly, but also the number of fully cellular container ships has expanded substantially. Because of the tense competition among ports in recent years, improving the operational efficiency of ports has become an important issue in containership operations. Arrangement of containers both within the container terminal and on the containership play an important role in determining the berthing time. The berthing time of a containership is mainly composed of the unloading and loading time of containers. Containers in a containership are stored in stacks, making a container directly accessible only if it is on the top of one stack. The task of determining a good container arrangement to minimize the number of re-handlings while maintaining the ship's stability over several ports is called stowage planning, which is an everyday problem solved by ship planners. The horizontal distribution of the containers over the bays affects crane utilization and overall ship berthing time. In order to increase the terminal productivity and reduce the turnaround time, the stowage planning must conform to the berth design. Given the configuration of berths and cranes at each visiting port, the stowage planning must take into account the utilization of quay cranes as well as the reduction of unnecessary shifts to minimize the total time at all ports over the voyage. This dissertation introduces an optimization model to solve the stowage planning problem with crane utilization considerations. The optimization model covers a wide range of operational and structural constraints for containership load planning. In order to solve real-size problems, a meta-heuristic approach based on genetic algorithms is designed and implemented which embeds a crane split approximation routine. The genetic encoding is ultra-compact and represents grouping, sorting and assignment strategies that might be applied to form the stowage pattern. The evaluation procedure accounts for technical specification of the cranes as well as the crane split. Numerical results show that timely solution for ultra large size containerships can be obtained under different scenarios

A multi-objective optimization approach to optimal sensor placement of irregular LSF structures

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Improving SCATS Operation during Congestion Periods Using Internal/External Traffic Metering Strategy

Traffic metering is one of the effective strategies of preventing gridlock at urban signalized intersections during oversaturated conditions. This strategy could be implemented by adjusting signal timing schemes of the connected intersections of congested network in dynamic setting. This paper demonstrates the benefits of internal/external traffic metering strategy on a real case study in Tehran, the capital of Iran. For this purpose, the model outputs have been considered as input to set of SCATS scenarios for signal timing. In each test case the system is forced to use plans obtained from the model instead of using common built-in plans that had been used before, and the performance is measured using the VISSIM simulator to show differences. The results show significant improvement in network average travel time when using internal/external traffic metering strategy. Additionally, the average queue lengths are maintained near the optimal level since the model utilizes upstream arterial capacity

Quantifying non-recurring congestion impact on secondary incidents using probe vehicle data

As a significant cost and externality to economic efficiency, congestion is partly caused by traffic incidents. For more systematic, planned and coordinated incident management, quantifying a primary incident’s impact on secondary incidents is crucial and challenging. Many thresholds have been suggested in defining the secondary incidents, but there is no universal acceptance of a definition and corresponding set of measurement parameters. Static threshold methods cannot consider the actual representation of prevailing traffic conditions when the incidents took place. On the other hand, dynamic methods have disadvantages because necessary traffic detector data may not be available, and replication of the incidents using a simulation package can be time consuming. The novelty of this study rests in the attempt of a probe vehicle technique for capturing the dynamics of traffic evolution during the primary-crash incidents. Compared to the previous thresholds which have many errors, proposed speed contour map from Traffic Message Channel codes provides accurate feasible area for identification of secondary incidents

Impact of Data Source on Travel Time Reliability Assessment Impact of Data Source on Travel Time Reliability Assessment Final Project report Mid-Atlantic Universities Transportation Center Title and Subtitle: Impact of Data Source on Travel Time Reliabili

Travel time reliability measures are becoming an increasingly important input to the mobility and congestion management studies. In the case of Maryland State Highway Administration, reliability measures are key elements in the agency's Annual Mobility Report that is used for both transportation planning and operations. Recent advancements in vehicle tracking technologies have provided both private sectors and transportation agencies with multiple technologies for travel time data collection. This paper investigates the effect of data source selection on travel time reliability assessment. One year data from two independent sources, probe and Bluetooth, on two major freeway corridors in Maryland are used for travel time reliability analysis. Bluetooth sensors are permanently installed on multiple points of these two corridors and probe data are provided by INRIX. A statistical method is applied to compare reliability measures obtained from both sources. Several travel time reliability performance measures are studied. Results show that some reliability measures are more sensitive to the data source than the others. It is also shown that performance measures for HOV and general purpose lanes must be calculated separately

Current harmonic losses resulting from first and second generation LED lights replacement with sodium vapor lights in a LV feeder

The LED lamps require a DC current for proper functioning, thus, in order to supply this current, the diode bridge rectifiers in the internal circuit of these lamps are used. One of the problems in the old generation LEDs was the low power factor in these lamps. After development of electronic devices with soft switching, a new generation of LED lamps with high power factor has come into the commercial market. For power factor correction of LED lamps, the single-stage power factor correction circuits (PFC) are often used including a DC-DC boost converter with pulse width modulation and transformer. Despite the recent developments, the low power quality and harmonic current distortion of LED lamps is one of the basic challenges. Although a low power LED lamp doesn't have significant harmonic effects in distribution networks, however, the integration of LED lamps, especially in the lighting feeders, would increase the harmonic current distortion and reduce the power quality. Increase in the current harmonics will increase the ohmic losses along the Feeder conductors of the distribution network. In this article, there has been an attempt to examine the decreased harmonic power losses resulting from replacement of older generation (150Watt) 38 LED lights (without power factor correction circuit) and modern LED lights (with single-stage power factor correction circuit) with (160Watt) sodium vapor lamps in a lighting feeder on a street. The low voltage feeder and LED lights information has been taken from a real network. Results show that by installing LED street lights with power factor correction circuit (PFC), the harmonic losses along the network conductors are decreased by 11% compared to the sodium vapor lights. In contrast, the harmonic losses are increased by 57% with LED lights replacement without power factor correction (PFC)

Moyamoya Disease Mimicking Encephalitis

Moyamoya disease is a rare vaso-occlusive illness with an unknown etiology characterized by stenosis of the internal carotid arteries with spontaneous development of a collateral vascular network. A 15-month-old girl was referred to the emergency ward of Imam Reza Hospital due to decreased level of consciousness, focal seizures and fever during the previous 24 hours with an impression of encephalitis. Physical examination revealed left side hemiparesis; however brain CT-Scan did not show any significant lesions. Initial therapy with vancomycin, ceftriaxone and acyclovir was administered. CSF analysis did not show any abnormality and the blood as well as CSF cultures results were negative. Brain MRI showed hyperintensity at right frontal and parietal regions, suggesting vascular lesion. Magnetic resonance angiography (MRA) showed bilaterally multiple torsions in vessels at the basal ganglia consistent with moyamoya vessels. In all children exhibiting encephalitis, vascular events such as moyamoya disease should be considered. Brain MRI is a critical tool for this purpose. Common causes of encephalitis such as herpes simplex should also be ruled out

Correlation of Pre-pregnancy Body Mass Index, Prenatal Weight Gain and Gestational Diabetes – A Case-Control Study

Introduction: Obese and overweight women are more prone to gestational diabetes. Body mass index and weight gain during pregnancy play an important role in pregnancy and is considered as an important indicator of maternal and neonatal health. Because the prevalence of obesity in Yazd is remarkable, we studied the relationship between gestational diabetes with Pre-pregnancy BMI and weight gaining during pregnancy in pregnant women in Yazd. Methods: This case-control study was conducted on 336 pregnant women who had just given birth, who they consisted of 168 pregnant women with gestational diabetes and 168 healthy pregnant women as case and control group, respectively. We gathered data from the information recorded in the health information system. In this study, Chi-square, independent t-test, and correlation test were used to analyze the data by using the SPSS23 software. Results: The present study showed that the average pre-pregnancy BMI and the average weight gaining during pregnancy until screening for gestational diabetes were significantly higher in cases than controls (P<0.05). Also, there was a significant reverse correlation between pre-pregnancy BMI and weight gain during pregnancy(r = -0.27, P <0.001). Conclusion: Since BMI is one of the modifiable risk factors, we should give all women good training on the quality of their diet for having proper weight before pregnancy and appropriate weight gain during pregnancy