University of Peradeniya

About: University of Peradeniya is a education organization based out in Kandy, Sri Lanka. It is known for research contribution in the topics: Population & Poison control. The organization has 5970 authors who have published 7388 publications receiving 197002 citations.

Power quality and stability improvement of a wind farm using STATCOM supported with hybrid battery energy storage

Abstract: A large penetration of wind generation info the power system will mean that poor power quality and poor stability margins cannot be tolerated from wind farms This requires that methods to improve power qualify and stability for such systems be found The static compensator (STATCOM) with hybrid battery energy storage (BES) has great potential to fulfil this role, though considerable advances in the control of this system are still to be made From an economic point of view, rating the STATCOM for steady-state power-quality improvement duty is appropriate Rating the STATCOM to absorb large amounts of additional power in excess of its transient overload capability during network faults is inappropriate A hybrid of BES and braking resistor is therefore proposed A new hybrid STATCOM–BES control technique is developed and discussed in the context of improving the stability and power quality to fixed speed, induction generator, wind turbines The variation of the network voltage, active and reactive power with the fluctuation of the wind generation is studied A wind generation system with a STATCOM battery energy storage unit and the new control was simulated and the results demonstrate that both power quality and the stability margin can be improved significantly for wind farms

Measuring Microenterprise Profits: Don't Ask How the Sausage is Made

Abstract: A large share of the world's poor is self-employed. Accurate measurement of profits from microenterprises is therefore critical for studying poverty and inequality, measuring the returns to education, and evaluating the success of microfinance programs. But a myriad of problems plague the measurement of profits. The authors report on a variety of different experiments conducted to better understand the importance of some of these problems and to draw recommendations for collecting profit data. In particular, they (1) examine how far we can reconcile self-reported profits and reports of revenue minus expenses through more detailed questions; (2) examine recall errors in sales and report on the results of experiments which randomly allocated account books to firms; and (3) ask firms how much firms like theirs underreport sales in surveys like this, and have research assistants observe the firms at random times 15-16 times during a month to provide measures for comparison. The authors conclude that firms underreport revenues by about 30 percent, that account diaries have significant effects on both revenues and expenses but not on profits, and that simply asking profits provides a more accurate measure of firm profits than detailed questions on revenues and expenses.

Soil resources and topography shape local tree community structure in tropical forests

Abstract: Both habitat filtering and dispersal limitation influence the compositional structure of forest communities, but previous studies examining the relative contributions of these processes with variation partitioning have primarily used topography to represent the influence of the environment. Here, we bring together data on both topography and soil resource variation within eight large (24–50 ha) tropical forest plots, and use variation partitioning to decompose community compositional variation into fractions explained by spatial, soil resource and topographic variables. Both soil resources and topography account for significant and approximately equal variation in tree community composition (9–34% and 5–29%, respectively), and all environmental variables together explain 13–39% of compositional variation within a plot. A large fraction of variation (19–37%) was spatially structured, yet unexplained by the environment, suggesting an important role for dispersal processes and unmeasured environmental variables. For the majority of sites, adding soil resource variables to topography nearly doubled the inferred role of habitat filtering, accounting for variation in compositional structure that would previously have been attributable to dispersal. Our results, illustrated using a new graphical depiction of community structure within these plots, demonstrate the importance of small-scale environmental variation in shaping local community structure in diverse tropical forests around the globe.

Business Training and Female Enterprise Start-Up, Growth, and Dynamics: Experimental Evidence from Sri Lanka

Abstract: We conduct a randomized experiment in Sri Lanka to measure the impact of the most commonly used business training course in developing countries, the Start-and-Improve Your Business (SIYB) program. In contrast to existing business training evaluations which are restricted to microfinance clients, we consider two more representative groups: a random sample of women operating subsistence enterprises, and a random sample of women who are out of the labor force but interested in starting a business. Both samples are randomized into three groups: a control group, a group invited to attend training, and a group invited to receive training and who receive a cash grant conditional on completing training. We track impacts over four rounds of follow-up surveys taken over two years and find that the short- and medium-term impacts differ. For women already in business, we find that although training alone leads to some changes in business practices, it has no impact on business profits, sales or capital stock. In contrast the combination of training and a grant leads to large and significant improvements in business profitability in the first eight months, but this impact dissipates in the second year. For women interested in starting enterprises, we find that business training speeds up the process of opening a business, and changes the selection of who operates a business by making the entrants less analytically skilled, but leads to no increase in net business ownership by our final survey round. Receiving a grant results in poorer women opening businesses, but again does not increase net business ownership. Training appears to have increased the profitability and business practices of the businesses started up, suggesting it may be more effective for new owners than for enhancing existing businesses.