A study of the impact of terrain and turbulence on the performance and fatigue loading of small wind turbines

Small wind turbines (SWT) are designed according to the international standard IEC 61400-2, which assumes the SWT experiences a set of standard wind conditions, developed through assumptions of flat terrain and normal turbulence models. In practice, other wind conditions can exist at SWT sites including winds, influenced by terrain, that feature speed and turbulence behaviour outside the set of standard conditions. This results in the turbines suffering operationally and structurally when operated in such terrains. In this study, wind conditions at two contrasting locations; one from built environment (Port Kennedy) and another from open terrain (Östergarnsholm), are analysed and benchmarked against the standard for comparison. The findings show that the longitudinal turbulence intensity (TIu) at Port Kennedy is higher than value estimated in the standard while the TIu at Östergarnsholm is within the standard’s estimate. These wind fields are used as inputs in the aeroelastic code, FAST, to investigate performance and loading of a 5 kW horizontal axis wind turbine. The findings suggest that elevated turbulence in Port Kennedy wind increases the output rotor power while the Port Kennedy wind also doubles the fatigue load on the turbine blades. The probability density function (PDF) of the wind speed increments reveal that the Port Kennedy wind shows the highest intermittency of turbulence at small timescales and this appears to manifest as higher intermittency of the rotor dynamic loads. The PDFs of rotor torque, thrust and blade flapwise bending moment all show increased likelihood of extreme events for the turbine operating in the built environment with reduced fatigue life than the same turbine operated in the open terrain. The conclusions are that the standard appears inadequate for SWTs sited in complex sites with non-standard wind conditions and requires modification to make it more inclusive of turbulent sites to assure their reliable deployment. Keyword: small wind turbine, terrain, turbulence, intermittency, fatigue loading, FAS

a case of Nepal

Thesis(Master) --KDI School:Master of Development Policy,2017Higher child mortality is often a common health issue in most developing countries and Nepal is not an exception. However, one positive development is how Nepal has been able to continuously reduce the child mortality rate, dropping from 133 deaths per one thousand live births in 1991 to 43 in 2011. This study aims to analyze the impact of mother’s education level and mother’s age at birth on child mortality. The study uses variables taken from the dataset of the Nepal Demographic and Health Survey (NDHS) 2006 and 2011. A logistic regression method of analysis with logit and probit estimation as well as OLS was conducted in order to find out the estimates for child survival. Consequently, the level of impact on child mortality was derived on the basis of child survival estimates. The results show that after controlling other socio-economic and proximate independent variables, 1 year increase in mother’s education leads to 0.3 percent increase in child survival rate. Likewise, a higher education level is associated with higher child survival rate. Similarly, child mortality and mother’s age at birth shows a curvilinear relationship. The study also identifies other relevant demographic variables associated with child mortality.CHAPTER 1 INTRODUCTION CHAPTER 2 LITERATURE REVIEW CHAPTER 3 DATA, METHOD AND MODEL CHAPTER 4 EMPIRICAL RESULT, DISCUSSION AND CONCLUSIONOutstandingmasterpublishedAnup KC

Dynamics of Undertory Shortleaf Pine (Pinus Echinata Mill.) And Hardwood after Thinning Shortleaf Pine Forests in the Southeastern United States

The shortleaf pine (Pinus echinata Mill.) population is consistently declining in southeastern United States. Shortleaf pine forests are thinned frequently to improve the growth and development of residual stands. But, the effect of thinning on growth and development of understory woody-plants in long term has not been extensively studied. We assessed the effects of thinning, overstory shortleaf pine characteristics, climatic, and topographic factors on shortleaf pine regeneration applying various predictive modeling techniques. We applied decision tree models to predict shortleaf pine regeneration. We also developed, evaluated, and compared the performance of three other predictive models to predict shortleaf pine regeneration. We used understory shortleaf pine data that were collected from shortleaf pine forests of Arkansas and Oklahoma spanning a period of 25 years following thinning and hardwood control treatments. The shortleaf pine densities have declined in every subsequent measurement since the first measurement of understory trees in 1996. Thinning treatments played a significant role on the understory shortleaf pine density. The decision tree model using the Gini criteria as the splitting rule to predict the shortleaf pine regeneration had a low misclassification rate of 7.6 percent. The decision tree model can be an efficient tool to make shortleaf pine stand management decisions. The best performing logistic regression model showed precipitation, plot age, site index, and overstory thinning were the significant inputs affecting shortleaf pine regeneration with validation misclassification rate of 8 percent. The best performing artificial neural network model predicted the shortleaf pine regeneration with validation misclassification rate of 7.6 percent, and cumulative lift of 5, 2.5 and 1.66 at depth of 20, 40 and 60 respectively. An artificial neural network model performed best to predict the shortleaf pine regeneration. Poor shortleaf pine regeneration performance over decades in study sites suggests the future of shortleaf pine dominated forests is questionable unless further regular silvicultural treatments are applied. We recommend continual hardwood removal every 10-15 years to obtain the satisfactory understory shortleaf pine regeneration in shortleaf pine forests of Arkansas and Oklahoma.Natural Resources and Ecology Managemen

Status of Soil Fertility in a Community Forest of Nepal

Soil is a complex mixture of mineral nutrients, organic matter, water, air and living organisms. The primary nutrients for plant growth are organic matter, nitrogen, phosphorus and potassium. In order to find the status of pH, organic matter (C), total nitrogen (N), available phosphorus (P) and available potassium (K) in forest soil, the study was conducted in Ghwangkhola Sapaude Babiyabhir Community Forest in Putali Bazaar Municipality-8, Syangja, Nepal. Soil parameters are analyzed through different standard methods followed worldwide by many soil scientists. Soil pH of sample in all three strata was slightly acidic and varies from 5.7 to 7.18. The carbon percentage was high and varies from 0.65% to 2.39%. The total nitrogen in soil was medium and varies from 0.09% to 0.12%. The concentration of available phosphorus in soil was high and varies from 73.71 kg/ha-93.23 kg/ha. The concentration of available potassium on soil was quiet low and varies from 2.54 kg/ha-4.23 kg/ha. Higher organic matter in the forest land indicate low activities of nitrogen losing process, which is due to the closed nutrient cycling and minimal disturbance in the natural forest system. So, addition of fertilizer rich in potassium and increasing pH is recommended to maintain potassium fertility and neutral pH in the forest soil

A Status of Health-related Quality of Life of Renal Recipients at a Transplant Center in Kathmandu

Background: Renal transplant is considered as the best treatment available to restore renal function in patients with renal failure. Health-related quality of life (HrQoL) is an important indicator for evaluating therapeutic outcomes and mortality in patients with end-stage renal disease, including renal failure. This study aimed to assess the health-related quality of life (HrQoL) of renal transplant recipients. Methods: This observational cross-sectional study involved 165 post renal transplant patients (mean age ± SD, 37.5 ± 10.7 years) from Tribhuvan University Teaching Hospital. Health-related quality of life was assessed by face-to-face interviews, using Kidney Transplant Questionnaire (KTQ-25) and scored according to the scoring algorithm of KTQ-25. Results: The mean score of HrQoL was 5.44 ± 0.80, with the highest score for appearance (6.65 ± 0.53) and the lowest for uncertainty/ fear dimension (4.29 ± 1.10). Several factors, including age, occupation, loan, length of renal replacement therapy, and time since transplantation were significantly associated with different dimensions KTQ-25 questionnaire (all, p < 0.05). Conclusion: As uncertainty/fear affected the quality of life most, counseling programs for recipients are needed focusing on psychological wellbeing. Although funding is available for patients with end-stage renal failure from the government, that does not seem to be adequate for them

Assessing Tourism Potential In Bhaktapur Durbar Square, Nepal

<p>Tourism is one of the most promising driver and contributor of the world economy having significant role in sustainable development, economic upliftment and social benefits. It has the potential to contribute towards environmental protection and poverty reduction. Prior to investment in tourism, concerned authorities must know the condition of respective tourist resources, their attractiveness and levels of touristic demand. Very few studies in Nepal have made an effort to quantify the tourism potential in cultural, historical and religious sites such as Bhaktapur Durbar Square. With an objective to assess the tourism potential of Bhaktapur Durbar Square using Weighted Sum Method, this study was carried out from start of June to the end of July in 2013. For this purpose, questionnaire survey with tourists, private businesses and public sector institutions; focus group discussion and key informant interview with tourism enterpreneur and local government officer was carried out. The tourism potential was found to be high with a strength of exceptionally rich cultural, historical and religious heritage, favourable geographical situation, positive image of local Newari food products and friendly and welcoming local people. The areas of weaknesses were lack of tourism infrastructures and services, lack of tourist information and weak management of tourist area. Hence, to utilise the tourism potential of Bhaktapur Durbar Square to the fullest for the economic upliftment of its inhabitants, promotional activities such as tourism fairs, festivals, cultural dances and events should be conducted at regular intervals with prompt security services.</p> <p>International Journal of Environment, Volume-2, Issue-1, Sep-Nov 2013, Pages 250-261</p> <p>DOI: <a href="http://dx.doi.org/10.3126/ije.v2i1.9225">http://dx.doi.org/10.3126/ije.v2i1.9225</a></p

Pyopericardium progressing to cardiac tamponade in a patient with dengue fever

Pyopericardium is a rare cause of cardiac tamponade. We present a case of a dengue fever patient who presented with cellulitis of the upper limbs, later manifesting cardiac tamponade, which was fatal. Although echocardiography on admission revealed a small pericardial effusion only, it later manifested as tamponade, causing cardiogenic shock. Staphylococcus pyopericardium was found later. Early identification could be possible with bedside point-of-care ultrasonography and echocardiography. Emergent pericardiocentesis or pig tail drain placement is life saving

The suitability of the IEC 61400-2 wind model for small wind turbines operating in the built environment★

This paper investigates the applicability of the assumed wind fields in International Electrotechnical Commission (IEC) standard 61400 Part 2, the design standard for small wind turbines, for a turbine operating in the built environment, and the effects these wind fields have on the predicted performance of a 5 kW Aerogenesis turbine using detailed aeroelastic models developed in Fatigue Aerodynamics Structures and Turbulence (FAST). Detailed wind measurements were acquired at two built environment sites: from the rooftop of a Bunnings Ltd. warehouse at Port Kennedy (PK) (Perth, Australia) and from the small wind turbine site at the University of Newcastle at Callaghan (Newcastle, Australia). For both sites, IEC 61400-2 underestimates the turbulence intensity for the majority of the measured wind speeds. A detailed aeroelastic model was built in FAST using the assumed wind field from IEC 61400-2 and the measured wind fields from PK and Callaghan as an input to predict key turbine performance parameters. The results of this analysis show a modest increase in the predicted mean power for the higher turbulence regimes of PK and Callaghan as well as higher variation in output power. Predicted mean rotor thrust and blade flapwise loading showed a minor increase due to higher turbulence, with mean predicted torque almost identical but with increased variations due to higher turbulence. Damage equivalent loading for the blade flapwise moment was predicted to be 58% and 11% higher for a turbine operating at Callaghan and PK respectively, when compared with IEC 61400-2 wind field. Time series plots for blade flapwise moments and power spectral density plots in the frequency domain show consistently higher blade flapwise bending moments for the Callaghan site with both the sites showing a once-per-revolution response