Environmental changes in the western Black Sea related to anthropogenic and natural conditions

The Black Sea northwestern shelf (NWS) ecosystem has been subjected to the strongest anthropogenic pressure of the entire Black Sea as about 80% of the freshwater runoff is discharged there.This paper presents a review of the global environmental changes related mainly to increased eutrophication in the western Black Sea basin.A case study (CoMSBlack 92a cruise) attempts to highlight the interaction of some natural and anthropogenic factors responsible for specific chemical and biological features in the western Black Sea environment. The significance of processes located near the Danube river mouth, which, due to their relatively small space scale, have not been recognized before, is clarified. Hydrological processess of specific importance to the distribution and transformation of antropogenic inputs are river plume dynamics, coastal upwelling and mixing and downwelling over the shelf break and slope in this part of the basin. A layer of low hydrological variability (“conservative layer”) appears to be a natural feature of the area, hypothesized to precondition specific biological and chemical processes there.The results suggest that the interplay between the Danube anthropogenic nutrient load with the natural hydrological fronts and gradients provides opportunities for enhanced biological activity thus contributing to the global environmental changes in the Black Sea NWS.     

Non-linear utility functions in models of travel choice behavior

Models of individual choice behavior have been extensively developed and used in travel prediction during the last ten years. These models are generally formulated with utility functions that are linear in parameters. Theories of economics and psychology suggest that the true relationship between service variables and utility is non-linear. In this paper we demonstrate that non-linear transformations of time and cost variables produce statistically significant improvements in the model estimated, have a theoretically appealing interpretation, and lead to managerially important differences in policy evaluations. These results support the need to refine the specification of choice utility functions based on theoretical considerations and empirical research.     

Spatial price equilibrium sensitivity analysis

A direct approach to performing sensitivity analysis for a spatial price equilibrium problem with nonlinear transportation cost, commodity supply and commodity demand functions is presented. The first order derivatives of all decision variables with respect to parameter perturbations are shown to be expressable in a simple from which requires inversion of a matrix whose rank is the number of regions considered. A typical network usually involves several hundred regions and several thousand links; thus, by working with a matrix whose rank depends only on the number of regions rather than the number of links, computer storage is minimized and the necessary matrix inversion is made feasible, enabling us to perform the sensitivity analyses of very large nonlinear equilibrium problems. An example is presented to demonstrate application of the method. The approach taken here is also adaptable to the sensitivity analysis of Wardropian equilibrium problems.     

An analysis of seasonality of non-OPEC supply

The purpose of this study is first to find out whether quarterly averages of non-OPEC (Organization of the Petroleum Exporting Countries) supply follow a seasonal pattern. If that is mathematically established, then, second, it is attempted to estimate the best seasonal factors to decompose the forecast yearly average into quarterly averages. A set of historical data consisting of quarterly supply averages of individual countries, regional subtotals and the aggregate non-OPEC supply for the period 1973-2002 forms the basis of the analysis. The study applies Fourier analysis to quarterly supply series to test for seasonality, and provides estimates of seasonal factors for the years 2000-2002 by applying the so-called X-11 decomposition method to the historical annual averages. The accuracy of the results of the application of X-11 is then tested. It is demonstrated that the combination of the Fourier and X-11 methods provides mostly acceptable and in some cases, such as that of China, impressively accurate forecast quarterly supply averages.     

Discrete Adaptive Active Suspension for Hardware Implementation

This paper presents a discrete adaptive control approach for an active suspension. The study involves formulation of an active suspension as a digital controller problem involving the time delays. A nonlinear time varying (NTV), single input single output (SISO) suspension model is considered for the analysis. A discrete model reference adaptive control (DMRAC) approach with recursive least square (RLS) estimation is used to form the controller. The controller is designed to maintain the static equilibrium irrespective of dynamic load variations as a disturbance force on the model. Simulation results for deterministic and stochastic inputs are presented to substantiate the approach. Results indicate good performance of adaptive controller even for large dynamic variations of the model and has the potential for a successful hardware implementation.     

The legal framework

The major and minor ports in India operate within different legal frameworks. Both allow privatization, but impose different conditions. Administrative culture has acted as a constraint on privatization in the major ports; private development at the minor ports has been very responsive to the amount of assistance offered by individual States.     

Thermal deformations in typical maglev guideway structures

Thermal gradients and related deformations induced in elevated Maglev guideways by temperature variations in their environment have been predicted by a mathematical model. The deflections induced by thermal gradients in typical guideways are found to exceed specified limits for acceptable operation of an electromagnetic suspension system vehicle unless measures are taken to reduce the thermal gradients and related deflections by suitable treatment of the guideway surfaces.     

An investigation of passenger interchange and train standing time at LRT stations: (ii) Estimation of standing time

The standing-time of trains at urban rail stations is pertinent to determining the line capacity and fleet size. The assumption of uniform boarding and alighting leads to under-estimation of the standing time. It is shown that the train standing-time is related to the fraction of boarders and the maximum demand for boarding and alighting at a door. It is further shown that the probability distribution of passengers at a door depends on the platform entrance locations. A methodology that takes into account the above factors is proposed for estimating the train standing-time.     

脑血管病和颅内肿瘤患者CSF-CK-BB实验与临床研究

采用层析荧光改良法对84例脑血管病（CVD）和颅内肿瘤（ICT）患者脑脊液（CSF）中脑型肌酸激酶同功酶（Brain Type Creatine Kinase Isoenzyme,CK-BB）活性作了测定。结果表明,在CVD急性期和ICT患者的CSF-CK-BB活性均有明显升高,且以出血性卒中（HCVD）的升高最为显著,其次为ICT,而缺血性卒中（ICVD）的升高则相对较低;同时CSF-CK-BB活性升高与CVD和ICT患者脑损伤的程度、范围和预后相关,而与ICT的病理性质及瘤腔内坏死范围无关。     

An examination of the determinants of day-to-day variability in individuals' urban travel behavior

Day-to-day variability in individuals' travel behavior (intrapersonal variability) has been recognized in conceptual discussions, yet the analysis and modeling of urban travel are typically based on a single day record of each individual's travel. This paper develops and examines hypotheses regarding the determinants of intrapersonal variability in urban travel behavior.Two general hypotheses are formulated to describe the effects of motivations for travel and related behavior and of travel and related constraints on intrapersonal variability in weekday urban travel behavior. Specific hypotheses concerning the effect of various sociodernographic characteristics on intrapersonal variability are derived from these general hypotheses. These specific hypotheses are tested empirically in the context of daily trip frequency using a five-day record of travel in Reading, England.The empirical results support the two general hypotheses. First, individuals who have fewer economic and role-related constraints have higher levels of intrapersonal variability in their daily trip frequency. Second, individuals who fulfil personal and household needs that do not require daily participation in out-of-home activities have higher levels of intrapersonal variability in their daily trip frequency.