On Identifying Disaster-Related Tweets: Matching-based or Learning-based?

Social media such as tweets are emerging as platforms contributing to situational awareness during disasters. Information shared on Twitter by both affected population (e.g., requesting assistance, warning) and those outside the impact zone (e.g., providing assistance) would help first responders, decision makers, and the public to understand the situation first-hand. Effective use of such information requires timely selection and analysis of tweets that are relevant to a particular disaster. Even though abundant tweets are promising as a data source, it is challenging to automatically identify relevant messages since tweet are short and unstructured, resulting to unsatisfactory classification performance of conventional learning-based approaches. Thus, we propose a simple yet effective algorithm to identify relevant messages based on matching keywords and hashtags, and provide a comparison between matching-based and learning-based approaches. To evaluate the two approaches, we put them into a framework specifically proposed for analyzing disaster-related tweets. Analysis results on eleven datasets with various disaster types show that our technique provides relevant tweets of higher quality and more interpretable results of sentiment analysis tasks when compared to learning approach

Level-k Phylogenetic Network can be Constructed from a Dense Triplet Set in Polynomial Time

Given a dense triplet set $\mathcal{T}$, there arise two interesting questions: Does there exists any phylogenetic network consistent with $\mathcal{T}$? And if so, can we find an effective algorithm to construct one? For cases of networks of levels $k=0$ or 1 or 2, these questions were answered with effective polynomial algorithms. For higher levels $k$, partial answers were recently obtained with an $O(|\mathcal{T}|^{k+1})$ time algorithm for simple networks. In this paper we give a complete answer to the general case. The main idea is to use a special property of SN-sets in a level-k network. As a consequence, we can also find the level-k network with the minimum number of reticulations in polynomial time

PREMILINARY RESEARCH ON ARSENIC POLLUTION OF SURFACE AND GROUND WATER IN TRA NANG GOLD EXPLOITATION REGION-LAM DONG PROVINCE AND CAO LANH TOWN-DONG THAP PROVINCE

Joint Research on Environmental Science and Technology for the Eart

DIURNAL CHANGE OF PAHS AND NITRO-PAHS IN THE ATMOSPHERIC PARTICULATE MATTER AT THE ROADSIDE IN HO CHI MINH CITY, VIETNAM

Joint Research on Environmental Science and Technology for the Eart

Further Discussion On Educational Issues And Case Teaching Method For Economic Students Via Case Studies

Vietnam has begun to apply case stude method teaching for economic and business students in clleges and universities because it has provided them with real situation and problem solving skills. By using experiences, synthesis and quantitative methods ombined with dialectical materialism methods, this study prove examples of case studies in Bahrain and in Vietnam, in the context og educationin globalization, it is better to propose innovative educational methods for strengthening educational policies and for educating studets also, for instance, in economic field. In developing countries such as Vietnam, in Asia and in the world, case teaching method has been usedf widely for economic major students in clooges and unievrsities. Therefore, This study will menitone case method benefits such as real worl problems, solvin gproblem skill enhancement and representative and ttractiveness for learning

Understanding Problems of High Polymer Demand in Sludge Dewatering for Better Sludge Management

University of Technology Sydney. Faculty of Engineering and Information Technology.High polymer demand in sludge conditioning and dewatering is an unavoidable aspect of the water industry. Understanding interaction mechanisms between sludge particles and conditioning polymers in sludge dewatering is necessary to: firstly, maximize dewatered cake solids content; and secondly, to minimize polymer demand for conditioning. , two scientific methodologies, namely the ‘y-intercept’ concept and Higgins modified centrifugal technique (Higgins MCT) were used to identify the optimum polymer demand and type for effective conditioning and dewatering. Results from the ‘y-intercept’ concept show that a large amount of polymer required during conditioning of anaerobically digested sludge (ADS) is mainly due to the neutralization of soluble biopolymers or extracellular polymeric substances (EPS) in sludge. In contrast, conditioning of aerobically digested sludge (AEDS) and waste activated sludge (WAS) is mostly controlled by a polymer bridging mechanism. The results indicated that, in order to achieve maximum dewatering performance with minimum conditioning polymer requirement, high charge density polymers are suitable for ADS while branched (or cross-linked) polymers can be used for AEDS and WAS. In addition, the new lab-scale technique, Higgins MCT, was successfully established and implemented for measuring cake solids content achievable by centrifuge and determining the optimum polymer demand (OPD). The Higgins MCT also helped to understand the relationship between digestion, conditioning, and dewatering. It has been demonstrated that excess amounts of soluble EPS released in digestion can lead to high polymer demand for sludge dewatering. Elucidation of how much soluble EPS contribute to polymer demand for conditioning is important to identify pathways to minimize chemical usage without compromising dewatering performance. Thus, , a simple and unique yet effective method for quantifying the contribution of soluble EPS to polymer requirement was developed. This was achieved through measuring the absorbance of the supernatant derived from conditioned digested sludge at the 191.5 nm wavelength. In addition, the role of tightly bound EPS in determining the dewatering performance of digested sludges was also investigated. Specifically, the study examined ADS and AEDS from seven full-scale wastewater treatment plants (WWTPs). Results showed that the concentrations of soluble EPS in the sludges varied between 92–1148 mg/L. The EPS in ADS was much higher than those of AEDS. Experimental results also demonstrated that higher amounts of polymers were wasted in “parasitic” reactions with soluble EPS. For example, for ADS, it was as high as 40–86% of the cationic polymer dose) while for AEDS, it was less in the range of 25–33%. The residual cationic polymer left in solution, after the parasitic reactions, was substantial and varied between 35–254 mg/L. Despite that, zeta potential values of dewatered sludge cakes remained negative, i.e. between -24 – -35 mV. This indicated that the residual soluble cationic polymers would not have been absorbed on the negatively charged sludge particles. This explained the relatively poor performances of the dewatering in the plants studied. The study results also suggested that the tightly bound EPS attached to the sludge particles would be responsible for the low dewatering performance. It is postulated that the tightly bound EPS would gelify and immobilize the water surrounding the sludge particles. , inter-relationships between wastewater and sludge treatment, specifically among Enhanced Biological Phosphorus Removal (EBPR), anaerobic digestion, and dewatering, were investigated to identify feasible approaches to reduce both chemical and transportation costs for the EBPR plants. EBPR and non-EBPR WWTPs were compared in this study in order to determine the effects of EPBR and anaerobic digestion (AD) on sludge conditioning and dewatering. Experimental results show that EPBR and AD resulted in significant decreases in divalent cations and generation of soluble EPS, leading to a deterioration of bio-flocculation of ADS particles and requiring extra polymer dose for effective ADS conditioning and dewatering. In the two-stage AD, acid phase led to significant increases in concentrations of soluble biopolymers (more than double) due to hydrolysis reactions which converse non-soluble biopolymers to soluble organic compounds. Therefore, proper control of the acid phase can help reduce the content of soluble EPS to an optimum value that could favor both flocculation while minimizing the chemical cost for conditioning