Mathematical Models and Computer Simulation of Nitrogen Concentration Profiles in Pulse Ion Nitrided Layers

IntroductionThedireCtcrt(DC)ionndriding,whichhasbeenopliedfOrmanyyears,didn'tthoroughlysolvetheionnitridingproblemofsomecomPlexwOrkPlacesinshapeandstrUctUreunhlthepulse-iondridingPrOcessingaroseIl].Recentresultsshowthatthearc-CUttin-offsystemsincircuitcanbecancelled,thishasmadethecOntrOlsystemsofionnitridingequiPmentandhaacestwbessimPlnygreatiyMorehaPOrtantiy,theexcellentschcequalityofthewOrkPiecetreatedhasa1sobeenObtainedemPlovingPulseionchdingcomParedwithDCionnitriding.InOrdertOr…     

Resolving the impact of short-term variations in physical processes impacting on the spawning environment of eastern Baltic cod: application of a 3-D hydrodynamic model

Variations in oxygen conditions below the permanent halocline influence the ecosystem of the Baltic Sea through a number of mechanisms. In this study, we examine the effects of physical forcing on variations in the volume of deep oxygenated water suitable for reproductive success of central Baltic cod. Recent research has identified the importance of inflows of saline and oxygenated North Sea water into the Baltic Sea for the recruitment of Baltic cod. However, other processes have been suggested to modify this reproduction volume including variations in timing and volume of terrestrial runoff, variability of the solubility of oxygen due to variations in sea surface temperature as well as the influence of variations in wind stress. In order to examine the latter three mechanisms, we have performed simulations utilizing the Kiel Baltic Sea model for a period of a weak to moderate inflow of North Sea water into the Baltic, modifying wind stress, freshwater runoff and thermal inputs. The model is started from three-dimensional fields of temperature, salinity and oxygen obtained from a previous model run and forced by realistic atmospheric conditions. Results of this realistic reference run were compared to runs with modified meteorological forcing conditions and river runoff.From these simulations, it is apparent that processes other than major Baltic inflows have the potential to alter the reproduction volume of Baltic cod. Low near-surface air temperatures in the North Sea, the Skagerrak/Kattegat area and in the western Baltic influence the water mass properties (high oxygen solubility). Eastward oriented transports of these well-oxygenated highly saline water masses may have a significant positive impact on the Baltic cod reproduction volume in the Bornholm Basin.Finally, we analysed how large scale and local atmospheric forcing conditions are related to the identified major processes affecting the reproduction volume.     

Locating new passenger facilities on a transportation network

This paper examines the problem of locating additional passenger facilities on a transportation network to supplement ones that already exist. A distinction is made between “supporting” facilities which operate only in concert with already existing ones and “new” facilities which are self-sufficient and operate independently. It is shown that, when the objective is to maximize the utility of travel times to all users, at least one set of optimal locations for the new facilities exist on the nodes of the network if the utility function for travel times is convex. This result is proven under very general conditions including the assumption of a probabilistic transportation network, i.e. a network where travel times on network branches are random variables. A straightforward algorithm for solving a specific simple case is also provided and the results are illustrated by examples.     

Stakeholder Perceptions of Seaport Resilience Strategies: A Case Study of Gulfport (Mississippi) and Providence (Rhode Island)

Climate change is having and will continue to have a range of negative impacts on social–environmental systems. Many ports, with their coastal locations and essential roles in regional and national economies, face particular exposure to storm impacts that may worsen with climate change. Currently in the United States port resilience planning falls primarily on port operators. Engaging a wider range of stakeholders in long-term seaport functioning may reduce risks from disruptive and potentially irreversible impacts of climate change. This study uses empirical data gathered through two case studies of highly exposed U.S. ports, Gulfport (MS) and Providence (RI), to identify strategies that port planners and external stakeholders consider feasible for enhancing their port's resilience. This article categorizes these resilience strategies and suggests the potential role that different stakeholders could play in facilitation and implementation.     

利用AGM求解粘弹性地基刚性梁的非线性控制微分方程（英文）

In the present paper a vibrational differential equation governing on a rigid beam on viscoelastic foundation has been investigated. The nonlinear differential equation governing on this vibrating system is solved by a simple and innovative approach, which has been called Akbari-Ganji’s method(AGM). AGM is a very suitable computational process and is usable for solving various nonlinear differential equations. Moreover, using AGM which solving a set of algebraic equations, complicated nonlinear equations can easily be solved without any mathematical operations.Also, the damping ratio and energy lost per cycle for three cycles have been investigated. Furthermore, comparisons have been made between the obtained results by numerical method(Runk45) and AGM. Results showed the high accuracy of AGM. The results also showed that by increasing the amount of initial amplitude of vibration(A), the value of damping ratio will be increased, and the energy lost per cycle decreases by increasing the number of cycle. It is concluded that AGM is a reliable and precise approach for solving differential equations. On the other hand, it is better to say that AGM is able to solve linear and nonlinear differential equations directly in most of the situations. This means that the final solution can be obtained without any dimensionless procedure.Therefore, AGM can be considered as a significant progress in nonlinear sciences.     

Hydrography and biogeochemistry of the north western Bay of Bengal and the north eastern Arabian Sea during winter monsoon

The north eastern Arabian Sea and the north western Bay of Bengal within the Indian exclusive economic zone were explored for their environmental characteristics during the winter monsoons of 2000 and 2001 respectively. The two regions were found to respond paradoxically to comparable intensities of the atmospheric forcing. There is an asymmetry in the net heat exchange of these two basins with atmosphere because of the varying thickness of barrier layer. During winter, the convective mixing in the Arabian Sea is driven by net heat loss from the ocean, whereas the Bay of Bengal does not contribute to such large heat loss to the atmosphere. It appears that the subduction of high saline Arabian Sea water mass is the mechanism behind the formation of a barrier layer in the northeast Arabian Sea; whereas that in the Bay of Bengal and the southeast Arabian Sea are already established as due to low saline water mass. The weak barrier layer in the Arabian Sea yields to the predominance of convective mixing to bring in nitrate-rich waters from the deeper layers to the surface, thereby supporting enhanced biological production. On the other hand, the river discharge into the Bay of Bengal during this period results in the formation of a thick and stable barrier layer, which insulates vertical mixing and provide oligotrophic condition in the Bay.     

An investigation of incident frequency,duration and lanes blockage for determining traffic delay

Traffic delay caused by incidents is closely related to three variables: incident frequency, incident duration, and the number of lanes blocked by an incident that is directly related to the bottleneck capacity. Relatively, incident duration has been more extensively studied than incident frequency and the number of lanes blocked in an incident. In this study, we provide an investigation of the influencing factors for all of these three variables based on an incident data set that was collected in New York City (NYC). The information about the incidents derived from the identification can be used by incident management agencies in NYC for strategic policy decision making and daily incident management and traffic operation. In identifying the influencing factors for incident frequency, a set of models, including Poisson and Negative Binomial regression models and their zero‐inflated models, were considered. An appropriate model was determined based on a model decision‐making tree. The influencing factors for incident duration were identified based on hazard‐based models where Exponential, Weibull, Log‐logistic, and Log‐normal distributions were considered for incident duration. For the number of lanes blocked in an incident, the identification of the influencing factors was based on an Ordered Probit model which can better capture the order inherent in the number of lanes blocked in an incident. As identified in this study, rain is the only factor that significantly influenced incident frequency. For incident duration and the number of lanes blocked in an incident, various factors had significant impact. As concluded in this study, there is a strong need to identify the influencing factors in terms of different types of incidents and the roadways where the incidents occured.     

E-TYPE雕塑

每年夏天的英国古德伍德速度节(GoodwoodFestival of Speed)上,最大的设计亮点是Goodwood House前的雕塑。在过去的十年间,这块艺术宝地一直被英国著名艺术家兼设计师Gerry Judah占领,今年也不例外。这里矗立的是一尊高达28米的捷豹E-Type,以此来庆祝此款跑车诞生50