Optimal Charging of Electric Vehicles in Smart Grid: Characterization and Valley-Filling Algorithms

Electric vehicles (EVs) offer an attractive long-term solution to reduce the dependence on fossil fuel and greenhouse gas emission. However, a fleet of EVs with different EV battery charging rate constraints, that is distributed across a smart power grid network requires a coordinated charging schedule to minimize the power generation and EV charging costs. In this paper, we study a joint optimal power flow (OPF) and EV charging problem that augments the OPF problem with charging EVs over time. While the OPF problem is generally nonconvex and nonsmooth, it is shown recently that the OPF problem can be solved optimally for most practical power networks using its convex dual problem. Building on this zero duality gap result, we study a nested optimization approach to decompose the joint OPF and EV charging problem. We characterize the optimal offline EV charging schedule to be a valley-filling profile, which allows us to develop an optimal offline algorithm with computational complexity that is significantly lower than centralized interior point solvers. Furthermore, we propose a decentralized online algorithm that dynamically tracks the valley-filling profile. Our algorithms are evaluated on the IEEE 14 bus system, and the simulations show that the online algorithm performs almost near optimality ($<1$ relative difference from the offline optimal solution) under different settings.Comment: This paper is temporarily withdrawn in preparation for journal submissio

Morphological and allozyme studies of small terrestrial snails( Opeas sp., Subulina sp., and Huttonella bicolor) collected from Peninsular Malaysia

Shell morphological characters and allozyme electrophoresis were used to study the relationships among six geographical populations of land snails collected from Peninsular Malaysia. Allozyme electrophoresis was used to study the genetic variations to complement the morphological features studied that included shell lengths, numbers of whorls and shell colour. Ten loci coding for six enzymes (MDH, LAP, ALP, PGM, G6PDH, and EST) could be reliably scored in samples from the six populations studied. The dendrogram showed two major clusters with one cluster comprising Subulinidae populations from Perak, Selangor, Johor, Terengganu, and Pahang while the other cluster included only the Streptaxidae Huttonella bicolor (red) population. The Subulinidae populations were grouped into two subclusters: one subcluster included the Subulina sp. populations from Perak, Selangor, and Johor, while the other subcluster included the Opeas sp. populations from Terengganu and Pahang. Morphological features can identify the different families ant therefore they can complement the allozyme genetic studies on the land snail populations. Like other reports in the literature, our results also underline the importance of a genetic approach in conjunction with a morphological approach, for discriminating land snail species. The present results suggest that small land snails, which were similar in colour but different in sizes, were not of the same family/genus

Use of different tissues of flat-tree oyster Isognomon alatus as biomonitors of bioavailabilities and contamination by Zn in the mangrove area of Peninsular Malaysia

Oyster is a net accumulator of metals, especially Zn, which can be used as a biomonitor of time—integrated records of bioavailable Zn fractions over its life time. Total soft tissues of oysters have been frequently used in metal bio-monitoring study. However, a lot of environmental and biological effects could iniluence the metal data. ln order to reduce such confounding factors, the use of different soft tissues in oysters is proposed in this study. The muscle, mantle plus gills, byssus and remaining soft tissues of flat-tree oyster Lwgnomon alatus, collected from the estuaries of Lukut (5 sites), Sepang Besar (2 sites) and one polluted site at Kg. Pasir Puteh, were analysed for Zn. Signiticant spatial differences in the accumulated Zn concentrations of the oysters (and hence bioavailabilities) were found between sampling sites and estuaries, and these could be attributed to anthropogenic inputs, including discharges of shrimp ponds (Lukut), animal husbandry (Sepang Besar), sewage, shipping and industrial efliuents (Kg. Pasir Puteh). The use of different soft tissues of I. alatus as biomonitors of bioavailability and contamination by Zn in the mangrove area of Peninsular Malaysia is proposed. The erroneous results due to spawning and the problem of defaecation before dissection could be potentially reduced by using the oyster muscle. Hence, a more accurate interpretation of the bioavailability and contamination by heavy metals in coastal waters could be obtained. Overall, the present baseline data based on different soft tissues of the oysters can be used for regular biomonitoring, considering the rapid land-based development in the coastal area of Peninsular Malaysia

Multivariate analysis of heavy metal concentrations in the different tissues of four intertidal clams from Peninsular Malaysia

Four species of clams (Macoma sp., Siliqua sp., Pharus sp. and Mactra sp.) were collected from the intertidal area of Peninsular Malaysia, Their different soft tissues (siphon, muscle, foot, mantle, gill and remaining soft tissues), and shells were analyzed for the concentrations of Cd, Cu, Fe, Ni, Pb and Zn. The relationships of heavy metals in the different tissues of clams were detennined using multivariate analyses including correlation analysis, cluster analysis and multiple linear stepwise regression analysis (MLSRA). Metal distribution in the clams were explained using correlation analysis, which indicated that the shell was not signihcantly (P> 0.05) correlated with other tissues and the shell is also clustered differently from the rest of soft tissues as indicated by the cluster analysis. Among the soft tissues, it was found that the gills and mantle of all clams were identified as the most influential tissues in the accumulation of heavy metals in the total soft tissues for the clams by MLSRA, The present study found that the distributions of heavy metals in the different tissues of clams were related to their differences in biological and ecological aspects. Since the multivariate analyses used in this study can reduce the cost and time involved in identifying an effective tissue to monitor the heavy metal(s) bioavailability and contamination (Yap et al. 2010), this preliminary finding provided an altemative for future environmental management in the intertidal area of Peninsular Malaysia

Heavy metal concentrations(CU, FE, NI AND ZN) in the clam, Glauconome virens, collected from the northern intertidal areas of Peninsular Malaysia.

Samples of the clam, Glauconome virens, were collected from Kg. Sg. Berembang (Perlis), Sungai Layar (Kedah) and Pantai Teluk Air Tawar (Pulau Pinang). Present study aimed to determine the heavy metal concentrations in the different parts of G. virens. Besides the shells, the soft tissues of the clam were dissected into the gill, muscle, foot, mantle, siphon and remainder and then Cu, Fe, Ni and Zn levels were determined. The concentrations of Cu, Fe, Ni and Zn in the different parts ranged from 4.77-38.8 ?g/g dry weight, 211-1328 ?g/g dry weight, 0.55-7.91 ?g/g dry weight and 10.2-296 ?g/g dry weight, respectively. In general, it was found that the other parts of soft tissues contained higher concentrations Cu and Fe. Meanwhile, the shell in general contained higher Ni from the remaining parts. As for Zn, higher concentrations were found in the gill than other parts. Future biomonitoring study on this clam species should be focused on the tissues (such as the remainder, shell and gill) to determine their potential as biomonitoring organs/materials

Sustainable Smart Transportation System: Through the Lens of a Smart City in an Emerging Country

Environmental and social sustainability continue to challenge urban development agendas, especially in emerging markets. Past literature on the topic of smart, sustainable cities has focused relatively less on developing countries – however, during the transient phase, such economies undergo several stages of development which this paper endeavors to investigate. The goal is to define key dimensions essential for evolving existing urban sites into a sustainable ecosystem. In this context, this study puts forward a framework consisting of five pillars: Scalability, Connection, Availability, Productivity, and Environment (SCAPE) to guide the implementation of sustainable cities in developing and tropical countries

Duration of untreated bipolar disorder: A multicenter study

Little is known about the demographic and clinical differences between short and long duration of untreated bipolar disorder (DUB) in Chinese patients. This study examined the demographic and clinical features of short (≤2 years) and long DUB (\u3e2 years) in China. A consecutively recruited sample of 555 patients with bipolar disorder (BD) was examined in 7 psychiatric hospitals and general hospital psychiatric units across China. Patients’ demographic and clinical characteristics were collected using a standardized protocol and data collection procedure. The mean DUB was 3.2 ± 6.0 years; long DUB accounted for 31.0% of the sample. Multivariate analyses revealed that longer duration of illness, diagnosis of BD type II, and earlier misdiagnosis of BD for major depressive disorder or schizophrenia were independently associated with long DUB. The mean DUB in Chinese BD patients was shorter than the reported figures from Western countries. The long-term impact of DUB on the outcome of BD is warranted

Dissolved heavy metals and water quality in the surface waters of rivers and drainages of the West Peninsular Malaysia

The dissolved concentrations of metals (Cd, Cu, Pb, Ni, Fe and Zn), temperature, total dissolved solids, pH, dissolved oxygen, salinity and conductivity were determined in the surface waters of 24 geographical sampling sites including city and urban drainages and rivers, from the west Peninsular Malaysia, collected in January to April 2005. From these sampling sites, the ranges (min-max) of dissolved metal concentrations (mg/L) were Cd: 0.001-0.055, Cu: 0.001-0.1773, Pb: 0.001-1.523, Ni: 0.001-0.246, Fe: 0.001-35.67 and Zn: 0.0001-0.609 while for the water quality are pH: 4.96-9.81, dissolved oxygen (0.39-7.26 mg/L), total dissolved solids (0.002-10.02 mg/L), salinity (0.00-8.93 ppt), conductivity (3.33-17423 μS/cm) and temperature (27.8-35.3�). Some sites with elevated dissolved concentrations of heavy metals and poor water quality indicated the anthropogenic inputs of industrial and urban wastes. Regular monitoring of water quality in all drainage waters is recommended