8,483 research outputs found
Arrival processes in port modeling: insights from a case study
This paper investigates the impact of arrival processes on the ship handling process. Two types of arrival processes are considered: controlled and uncontrolled. Simulation results show that uncontrolled arrivals of ships perform worst in terms of both ship delays and required storage capacity. Stock-controlled arrivals perform best with regard to large vessel delays and storage capacity. The combination of stock-controlled arrivals for large vessels and equidistant arrivals for barges also performs better than the uncontrolled process. Careful allocation of ships to the mooring points of a jetty further improves the efficiency
On the effect of ship arrival processes on jetty and storage capacity
Ports provide jetty facilities for ships to load and unload their cargo. Jetty capacity is costly and therefore limited, causing delays for arriving ships. However, ship delays are also costly, so terminal operators attempt to minimize their number and duration. Here, simulation has proved to be a very suitable tool. However, in port simulation models, the impact of the arrival process of ships on the model outcomes tends to be underestimated. This report considers three arrival processes: stock-controlled, equidistant, and uncontrolled. We assess how their deployment in a port simulation model,based on data from a real case study, affects the efficiency of the loading and unloading process, making a case for careful modeling of arrival processes in port simulations. Uncontrolled, which is an assumed arrival process property in many client-oriented simulations, actually performs worst in terms of both ship delays and required storage capacity. Stock-controlled arrivals perform best with regard to large vessel delays and storage capacity. Additional control of the arrival process through the application of a priority scheme in processing ships further impacts efficiency in all three cases
ZOBOV: a parameter-free void-finding algorithm
ZOBOV (ZOnes Bordering On Voidness) is an algorithm that finds density
depressions in a set of points, without any free parameters, or assumptions
about shape. It uses the Voronoi tessellation to estimate densities, which it
uses to find both voids and subvoids. It also measures probabilities that each
void or subvoid arises from Poisson fluctuations. This paper describes the
ZOBOV algorithm, and the results from its application to the dark-matter
particles in a region of the Millennium Simulation. Additionally, the paper
points out an interesting high-density peak in the probability distribution of
dark-matter particle densities.Comment: 10 pages, 8 figures, MNRAS, accepted. Added explanatory figures, and
better edge-detection methods. ZOBOV code available at
http://www.ifa.hawaii.edu/~neyrinck/vobo
Deletion of the forebrain mineralocorticoid receptor impairs social discrimination and decision-making in male, but not in female mice
Arrival Processes for Vessels in a Port Simulation
Ports provide jetty facilities for ships to load and unload their cargo. Jetty capacity is costly and therefore limited, causing delays for arriving ships. However, ship delays are also costly, so terminal operators attempt to min imize their number and duration. Here, simulation has proved to be a very suitable tool. However, in port simulation models, the impact of the arrival process of ships on the model outcomes tends to be underestimated. This report considers three arrival processes: stock-controlled, equidistant, and uncontrolled. We assess how their deployment in a port simulation model, based on data from a real case study, affects the efficiency of the loading and unloading process, making a case for careful modeling of arrival processes in port simulations. Uncontrolled, which is an assumed arrival process property in many client-oriented simulations,
actually performs worst in terms of both ship delays and required storage capacity.
Stock-controlled arrivals perform best with regard to large vessel delays and storage capacity. Additional control of the arrival process through the application of a priority scheme in processing ships further impacts efficiency in all three cases.Ports provide jetty facilities for ships to load and unload their cargo. Jetty capacity is costly and therefore limited, causing delays for arriving ships. However, ship delays are also costly, so terminal operators attempt to min imize their number and duration. Here, simulation has proved to be a very suitable tool. However, in port simulation models, the impact of the arrival process of ships on the model outcomes tends to be underestimated. This report considers three arrival processes: stock-controlled, equidistant, and uncontrolled. We assess how their deployment in a port simulation model, based on data from a real case study, affects the efficiency of the loading and unloading process, making a case for careful modeling of arrival processes in port simulations. Uncontrolled, which is an assumed arrival process property in many client-oriented simulations, actually performs worst in terms of both ship delays and required storage capacity. Stock-controlled arrivals perform best with regard to large vessel delays and storage capacity. Additional control of the arrival process through the application of a priority scheme in processing ships further impacts efficiency in all three cases
The classical limit for a class of quantum baker's maps
We show that the class of quantum baker's maps defined by Schack and Caves
have the proper classical limit provided the number of momentum bits approaches
infinity. This is done by deriving a semi-classical approximation to the
coherent-state propagator.Comment: 18 pages, 5 figure
REVISITING ANNA MOSCOWITZ\u27S KROSS\u27S CRITIQUE OF NEW YORK CITY\u27S WOMEN\u27S COURT: THE CONTINUED PROBLEM OF SOLVING THE PROBLEM OF PROSTITUTION WITH SPECIALIZED CRIMINAL COURTS
This article explores New York City\u27s non-traditional, judicially based response to prostitution. This article first recounts the history of New York City’s Women’s Court. It then examines the work of the Midtown Community Court, the “problem-solving court” established in 1993 to address criminal issues, like prostitution, in Midtown Manhattan. It also discusses the renewed concerns about sex work in New York and describe the movement, propelled by modern reformers, to address prostitution through specialty courts. It then contrasts the shared features and attributes of the Women’s Court and Midtown Court models. Finally, the article urges modern reformers to step back from the problem-solving court movement and their call for the creation of more such specialized criminal courts
The Adiabatic Instability on Cosmology's Dark Side
We consider theories with a nontrivial coupling between the matter and dark
energy sectors. We describe a small scale instability that can occur in such
models when the coupling is strong compared to gravity, generalizing and
correcting earlier treatments. The instability is characterized by a negative
sound speed squared of an effective coupled dark matter/dark energy fluid. Our
results are general, and applicable to a wide class of coupled models and
provide a powerful, redshift-dependent tool, complementary to other
constraints, with which to rule many of them out. A detailed analysis and
applications to a range of models are presented in a longer companion paper.Comment: 4 pages, 1 figur
Preoperative and Early Postoperative Quality of Life Predict Survival in Potentially Curable Patients with Esophageal Cancer
Background: In patients with esophageal cancer, evidence for prognostic significance of preoperative quality of life (QoL) is limited, while the prognostic significance of postoperative QoL has not been investigated at all. Aim: To determine whether preoperative and postoperative QoL measurements can predict survival independently from clinical and pathological factors, in patients with potentially curable esophageal adenocarcinoma. Methods: A randomized controlled trial was performed from 1994 to 2000 in two academic medical centres, comparing transthoracic and transhiatal esophagectomy. QoL questionnaires were sent before and 3 months after surgery (Medical Outcome Study Short Form-20 and Rotterdam Symptom Checklist). Uni- and multivariate Cox regression analyses were used to examine firstly the prognostic value of preoperative QoL and several clinical factors, and secondly of postoperative QoL, several clinical factors, and pathological staging. Results: Out of 220 randomized patients, 199 participated in the QoL-study. In the multivariate preoperative model physical symptom scale (p = 0.021), tumor length (p = 0.034), and endosonographic T-stage (p = 0.003) were predictive for overall survival. In the postoperative multivariate analysis, social functioning (p = 0.035), pain (p = 0.026), and activity level (p = 0.037) predicted survival, besides pathological T-stage (p < 0.001) and N-stage (p < 0.001). Conclusion: In the present paper the first large consecutive series of potentially curable esophageal cancer patients is presented in whom prospectively collected QoL data before and after potentially curative surgical resection were used to predict survival. Both preoperative (physical symptoms) and postoperative (social functioning, pain, and activity level) QoL subscales are independent predictors of survival in potentially curable patients with esophageal adenocarcinoma
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