Dynamic traffic congestion pricing mechanism with user-centric considerations

Thesis: S.M. in Transportation, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 85-95).In this thesis, we consider the problem of designing real-time traffic routing systems in urban areas. Optimal dynamic routing for multiple passengers is known to be computationally hard due to its combinatorial nature. To overcome this difficulty, we propose a novel mechanism called User-Centric Dynamic Pricing (UCDP) based on recent advances in algorithmic mechanism design. The mechanism allows for congestion-free traffic in general road networks with heterogeneous users, while satisfying each user's travel preference. The mechanism first informs whether a passenger should use public transportation or the road network. In the latter case, a passenger reports his maximum accepted travel time with a lower bound announced publicly by the road authority. The mechanism then assigns the passenger a path that matches with his preference given the current traffic condition in the network. The proposed mechanism introduces a fairness constrained shortest path (FCSP) problem with a special structure, thus enabling polynomial time computation of path allocation that maximizes the sequential social surplus and guarantees fairness among passengers. The tolls of paths are then computed according to marginal cost payments. We show that reporting true preference is a weakly dominant strategy. The performance of the proposed mechanism is demonstrated on several simulated routing experiments in comparison to user equilibrium and system optimum.by Kim Thien Bui.S.M. in Transportatio

Climate Change Impacts, Vulnerability Assessment and Economic Analysis of Adaptation Strategies in Ben Tre Province, Vietnam

Scientific database has proven that Vietnam is one of the most affected countries due to climate change impacts on aquaculture and economies of rural communities. Ben Tre region has suffered immensely from recent salt water intrusion. Climate change generates sea level rise, increase in temperature and salt water intrusion. In 2005 losses had increased to US$37 million. We conducted three focus group discussions (FGDs) to assist in the identification of vulnerable sectors and households and community adaptation strategies to climate change. Households were also evaluated based on the levels of vulnerability. Residents have requested the construction of a water treatment plant and a dike system. CEA is employed as the tool for evaluating the two planned adaptations: Building a freshwater-supplying factory and Building a sea dike system. Total costs include initial investment and annual operating costs. We also conducted a benefit cost analysis since the outcomes of the strategies are different. The distribution of vulnerability index showed that 31% of households are highly vulnerable to climatic risk while 56% of households are not vulnerable at all. The sea dike is three times more expensive than the freshwater plant. In addition to the higher investment, it is more costly to keep the sea dike under operation annually. The water treatment plant is more cost effective in servicing the communities with freshwater but the dike has a higher benefit cost ratio when all costs are internalized and secondary benefits to agriculture and aquaculture are considered.EEPSEA and WorldFish Cente

Climate Change Awareness and Impacts on Aquaculture in Poor Rural Coastal Communities, Ben Tre Province, Vietnam

Vietnam has been ranked as one of the countries in Asia with the highest vulnerabilities to climate change impacts on fisheries and aquaculture. Eight of those ten provinces are located in the Mekong River Delta, including Ben Tre Province. We conducted a study to identify the impacts of climate change events on Ben Tre province poor rural coastal communities, to evaluate their awareness and the effects of climate change events on aquaculture. Farmers were aware of changing climatic conditions and pointed out indicators of these changes: (1) Changes in production and culturing patterns, (2) Changes in housing designs, (3) Improvement in drinking water collection and increase in water procurement, (4) Pumping of fresh water in the shrimp ponds, and (5) Building of dikes to prevent salt water intrusion. About 90 percent of respondents indicated that they suffered losses from salt water intrusion. Total losses generated by salt water intrusion amounted to VND 1,599,803,000, equivalent to USD 77,151. Age, education and previous effects from climate change events affected knowledge and perception of severity of climate change events. Farmers who were engaged in aquaculture were more likely to be prepared for climate change events than those who were not.EEPSEA and WorldFish Cente

Research Trends in Evidence-Based Medicine: A Joinpoint Regression Analysis of More than 50 Years of Publication Data

Background Evidence-based medicine (EBM) has developed as the dominant paradigm of assessment of evidence that is used in clinical practice. Since its development, EBM has been applied to integrate the best available research into diagnosis and treatment with the purpose of improving patient care. In the EBM era, a hierarchy of evidence has been proposed, including various types of research methods, such as meta-analysis (MA), systematic review (SRV), randomized controlled trial (RCT), case report (CR), practice guideline (PGL), and so on. Although there are numerous studies examining the impact and importance of specific cases of EBM in clinical practice, there is a lack of research quantitatively measuring publication trends in the growth and development of EBM. Therefore, a bibliometric analysis was constructed to determine the scientific productivity of EBM research over decades. Methods NCBI PubMed database was used to search, retrieve and classify publications according to research method and year of publication. Joinpoint regression analysis was undertaken to analyze trends in research productivity and the prevalence of individual research methods. Findings Analysis indicates that MA and SRV, which are classified as the highest ranking of evidence in the EBM, accounted for a relatively small but auspicious number of publications. For most research methods, the annual percent change (APC) indicates a consistent increase in publication frequency. MA, SRV and RCT show the highest rate of publication growth in the past twenty years. Only controlled clinical trials (CCT) shows a non-significant reduction in publications over the past ten years. Conclusions Higher quality research methods, such as MA, SRV and RCT, are showing continuous publication growth, which suggests an acknowledgement of the value of these methods. This study provides the first quantitative assessment of research method publication trends in EBM

NGHIÊN CỨU THỰC NGHIỆM XÁC ĐỊNH CÁC THÔNG SỐ CÔNG NGHỆ SẤY GỖ CĂM XE (Xylia xylocarpa) TRÊN MÁY SẤY CHÂN KHÔNG HỒNG NGOẠI

We determined the appropriate technological parameters for Pyinkado on an infrared vacuum drier. The experimental matrix was set up according to Box and Hunter's quadratic rotational invariant multi-objective response surface optimization method to determine the technological parameters: drying temperature and infrared radiation intensity during drying. The results show that Pyinkado wood sized 20  50 500 mm, drying temperature 58.9 °C, and infrared radiation intensity 634.21 W/m2 are suitable for shortening drying time and reducing wood defect. After 27 hours of drying, the wood defect rate is 11.67%, with a moisture content of 10 ± 1%, which is very suitable for wood processing and manufacturing.Mục đích của nghiên cứu là xác định các thông số công nghệ sấy phù hợp cho gỗ Căm xe trên máy sấy chân không kết hợp gia nhiệt hồng ngoại. Ma trận thí nghiệm được lập theo phương án bất biến quay bậc hai của Box và Hunter, tối ưu hóa đa mục tiêu theo phương pháp đáp ứng bề mặt để xác định các thông số công nghệ: nhiệt độ sấy, cường độ bức xạ hồng ngoại trong quá trình sấy. Kết quả cho thấy khi sấy gỗ Căm xe kích thước 20  50  500 mm, nhiệt độ sấy 58,9 °C và cường độ bức xạ hồng ngoại 634,21 W/m2 giúp rút ngắn thời gian sấy và hạn chế tỷ lệ khuyết tật cho gỗ. Với thời gian sấy 27 giờ thì tỷ lệ khuyết tật của gỗ sau sấy là 11,67% và độ ẩm đạt 10 ± 1%, đáp ứng yêu cầu về độ ẩm trong gia công và chế biến gỗ

Prevalence of Zoonotic Metacercariae in Two Species of Grouper, Epinephelus coioides and Epinephelus bleekeri, and Flathead Mullet, Mugil cephalus, in Vietnam

Fishborne zoonotic metacercariae have not been reported from brackish water and marine fish from Vietnam waters although these parasites are common in the country's freshwater fish. Both wild-caught and cultured grouper (Epinephelus coioides and Epinephelus bleekeri), and mullet (Mugil cephalus) from brackish and marine waters located in Khanh Hoa province in central coastal Vietnam were examined, and found positive for zoonotic trematode metacercariae. From grouper, Heterophyopsis continua and Procerovum varium were recovered. The prevalence of H. continua ranged from 2.0 to 6.0% and that for P. varium ranged from 11.6 to 15.8%. Mullet were infected with Pygidiopsis summa and H. continua; both of these species are new records for Vietnam. The prevalence of P. summa in mullet was generally high, ranging from 17.6 to 75.5%, and was significantly higher than the prevalence of H. continua (2.5 to 32.4%). There were no significant differences in the prevalence of metacercariae between grouper from natural or cultured habitats, indicating that the highest risk of infection occurs in the wild-caught state prior to their placement in culture. Further, there was no difference in metacercarial prevalence between the 2 species of grouper. Infected wild-caught seed were only observed from January to October. Monthly variation in prevalence suggests seasonal variation in mullet infections occurs in this region with the highest transmission taking place from October to December. Basic investigations on the ecology and epidemiology of these intestinal flukes need to be carried out to determine their significance as a public health problem and the aspects of their biology that may be vulnerable to control interventions