Learning Automata based Shiftable Domestic Load Scheduling in Smart Grid: Accuracy and Fairness

Master's thesis in Information- and communication technology IKT590 - University of Agder 2016In this thesis, investigation is carried out on scheduling of shiftable loads which involves partly selection of loads within the power budget of operator. Domestic shiftable loads are scheduled along multiple timeslots with the considerations of the accuracy of scheduling in terms of optimization of capacity and of the fairness between appliances in terms of frequency of usage in smart grids. Since the scheduled load can not be over the capacity, the global optimal point is a combination of loads which are most close or equal to but not over the capacity. This optimization problem is shown to be NP hard, and has been formulated as a potential game. To solve this problem in a distributed manner, Learning Automata (LA) based methods are proposed. Although the LA based methods do not favour any participants of scheduling which can serve as a fair selection in the long run, the fairness among the loads in finite time is still worth studying. To make the scheduling process fair in short time, virtual coin game is employed into the scheduling. Simulations have been performed by implementing two LA methods, namely BLA and LR−I, under different number of timeslots, with and without consideration of coin game to evaluate and compare the results. Simulation results show that the accuracy in terms of the closeness of the converged result to the global optimal point achieved by both LA based scheduling methods is high and the fairness of the system is increased by applying the virtual coin game

Initial Experience of Percutaneous Nephrolithotomy at Lumbini Medical College

  Introduction: Renal stone disease is a challenging problem in urologic practice especially in our locality because of large stone burden and recurrence. Since ,the early 1980s when percutaneous nephrolithotomy (PCNL) was established for management of renal stones, open surgical procedures have virtually been replaced. PCNL is a safe, effective and minimally invasive approach compared to open surgery for patients with large single, multiple or staghorn stones. The aim of this prospective study was to evaluate and to review our experience with PCNL in management of renal and upper ureteric stones.   Methods: Prospective study carried out at Lumbini Medical College and Teaching Hospital during 1stJanuary 2011 to 31st October 2011. Sixty patients were evaluated and subjected to PCNL. After clinical investigations like ultrasonography (USG) and intravenous urography (IVU), once patients were found to have renal or upper ureteric stones they were informed and explained about PCNL, its likely complications, probable hospital stay, the cost of treatment and data were recorded along with the operative time, estimated blood loss, stone burden, stone-free rate, length of hospitalization and complications .Patients were followed up after three months to rule out recurrence of stones by plain abdominal x-ray of kidney, ureter and bladder and USG.   Results: Out of 60 patients 35 were male and 25 were female (M: F=1.4:1) with mean age of 37 years and were subjected to PCNL monotherapy. With the average stone size of 3.26cm, the mean operative time was 78 minutes. Complete stone removal achieved by PCNL alone in 60 cases, with insignificant residual small stones we achieved 97% stone clearance rate. The mean hospital stay was 3.7 days. No Serious complications were encountered, 9 (15%) patients required blood transfusion and 3 (5%) patients developed transient post-operative pyrexia.   Conclusion: PCNL is the first line treatment option for management of large renal stones which as monotherapy has advantages in removal of renal and upper ureteric stones and achieving excellent results with minimal morbidity

Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor

The efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electrical capacitance tomography (ECT) measurements. The two-dimensional images (along the reactor horizontal and vertical planes) of the fluidized bed are obtained from the CPFD simulations at different operating conditions. The CPFD model was developed in a commercial CPFD software Barracuda Virtual Reactor 20.0.1. The bubble behavior and bed fluidization behavior are characterized form the bubble properties: average bubble diameter, bubble rise velocity, and bubble frequency. The bubble properties were determined by processing the extracted images with script developed in MATLAB. The CPFD simulation results are compared with experimental data (obtained from the ECT sensors) and correlations in the literature. The results from the CPFD model and experimental measurement depicted that the average bubble diameter increased with an increase in superficial gas velocities up to 4.2 Umf and decreased with a further increase in gas velocities due to the onset of large bubbles (potential slugging regime). The bubble rise velocity increased as it moved from the lower region to the bed surface. The Fourier transform of the transient solid volume fraction illustrated that multiple bubbles pass the plane with varying amplitude and frequency in the range of 1–6 Hz. Further, the bubble frequency increased with an increase in superficial gas velocity up to 2.5Umf and decreased with a further increase in gas velocity. The CPFD model and method employed in this work can be useful for studying the influence of bubble properties on conversion efficiency of a gasification reactor operating at high temperatures.publishedVersio

Experience of Laparoscopic Cholecystectomy at Lumbini Medical College Teaching Hospital

  Introduction: The difficult gallbladder is the most common difficult laparoscopy being performed by generalsurgeons all over the world and the potential one that places the patient at significant risk. The present study aimed to study all the cases of laparoscopic cholecystectomy conducted in current setup at Lumbini Medical College and Teaching Hospital, to compare the results with the published literature and also analyze the complications and ways to decrease the incidence of conversion to open procedure.   Methods: Five hundred twenty five patients age 10-90 years, male:female ratio of 1:3.86 with body weight 45-65 kilogram, who had undergone laparoscopic cholecystectomy for symptomatic cholelithiasis without choledocholithiasis from April 2011 to April 2013 were studied.   Results: All the laparoscopic cholecystectomy (LC) were without major complications. Only nineteen out of five hundred twentyfive (3.6%) required conversion to open cholecystectomy (OC). Reasons for conversion included: dense omental or visceral adhesions; two (0.38%), unclear anatomy; 16 (3.04%), common bile duct injury; one (0.19%). There were 20 cases of shrunken gallbladder suspicious of malignancy but didn’t required conversion.   Conclusion: Laparoscopic cholecystectomy is the preferred method in our setup even in difficult cases

Correlation of serology with morphological changes in gastric biopsy of H. pylori infection

Background: Helicobacter pylori is involved in many gastrodeudonal complications and many diagnostic tests are available for its identification. The present study was done with the objective to evaluate the morphological changes induced by H. pylori in the gastric mucosa and to correlate them with the severity of the infection.Methods: This study was conducted in a tertiary care hospital from July 2013 to June 2014. 60 patients with symptoms of dyspepsia and requiring an upper gastrointestinal endoscopy were included in the study. Upper gastrointestinal endoscopy was performed on all patients. Hematoxylin and Eosin staining (H and E), modified Giemsa staining were performed on tissue sections and examined microscopically for gastritis and presence and absence of H. pylori.Results: Out of 60 patients, 33 were male and 27 were females. Serology by immunochromatography technique was positive in 41 patients. Serology was found to have a sensitivity and specificity of 90.90% and 59.25% respectively. H. pylori was positive in 28 cases on H and E. With a sensitivity and specificity of 84.84% and 100% respectively. H. pylori was positive in 33 cases on modified Giemsa with a sensitivity and specificity of 100%.Conclusions: Simultaneous morphologic and serological detection of H. pylori helps in its complete distribution and identification of its precancerous morphological nature

Pre-operative Hypoglycemia in Patients Presenting for Surgery: A Hospital Based Cross-sectional Study

Introduction: Peri-operative glycemic control is an important factor for post-operative recovery and is well protocoled for diabetic patients in every setup. It is not always so with non-diabetic patients. This study aimed to observe the pre-operative glucose level and prevalence of hypoglycemia in patients presenting for surgery and its association with the duration of nil per oral period (NPO), age and intravenous fluids used in the pre-operative period. Methods: A cross-sectional study was conducted in the Department of Anesthesiology in a Nepalese medical college including all the patients posted for elective surgery over a period of three months. Socio-demographic and clinical details of the participants were collected in the operating theatre. Duration of  NPO period and intravenous fluid prescribed in the pre-operative fasting period were recorded. A glucose strip test was performed on all the participants. Results: Participants were found to have fasted for an unnecessarily longer duration (12.84±2.27 hours). The incidence of hypoglycemia in patients posted for elective surgery was very high (43.3%). Ringer lactate and normal saline were equally prescribed (38.4%) and dextrose-normal saline was prescribed in the rest of the participants. Gender and type of intravenous fluids were positively correlated whereas NPO period was negatively correlated in overall participants though statistically insignificant. In hypoglycemic participants, we observed that lower glucose was influenced by pre-operative fluids, age and NPO duration. Conclusion: Pre-operative use of glucose-containing fluids during NPO period is an important step to prevent hypoglycemia and related consequences

A Learning Automaton-based Scheme for Scheduling Domestic Shiftable Loads in Smart Grids

In this paper, we consider the problem of scheduling shiftable loads, over multiple users, in smart electrical grids. We approach the problem, which is becoming increasingly pertinent in our present energy-thirsty society, using a novel distributed game-theoretic framework. In our specific instantiation, we consider the scenario when the power system has a local-area Smart Grid (SG) subnet comprising of a single power source and multiple customers. The objective of the exercise is to tacitly control the total power consumption of the customers’ shiftable loads so to approach the rigid power budget determined by the power source, but to simultaneously not exceed this threshold. As opposed to the “traditional” paradigm that utilizes a central controller to achieve the load scheduling, we seek to achieve this by pursuing a distributed approach that allows the users¹ to make individual decisions by invoking negotiations with other customers. The decisions are essentially of the sort where the individual users can choose whether they want to be supplied or not. From a modeling perspective, the distributed scheduling problem is formulated as a game, and in particular, a so-called “Potential” game. This game has at least one pure strategy Nash Equilibrium (NE), and we demonstrate that the NE point is a global optimal point. The solution that we propose, which utilizes the theory of Learning Automata (LA), permits the total supplied loads to approach the power budget of the subnet once the algorithm has converged to the NE point. The scheduling is achieved by attaching a LA to each customer. The paper discusses the applicability of three different LA schemes, and in particular the recently-introduced Bayesian Learning Automata (BLA). Numerical results, obtained from testing the schemes on numerous simulated datasets, demonstrate the speed and the accuracy of proposed algorithms in terms of their convergence to the game’s NE point.publishedVersionNivå

Improving fertilizer recommendations for Nepalese farmers with the help of soil-testing mobile van

Smallholder farmers dominate agriculture in Nepal. These farmers have poor knowledge about agriculture and lack of support for soil management and integrated plant-nutrient systems. Focusing on the importance and need for soil-fertility management, a soil-testing mobile van program has recently been introduced in Nepal by Soil Management Directorate, Hariharbhawan. With the introduction of the mobile lab, famers can get their soil tested for nutrient deficiencies and fertilizer requirements at their doorsteps. Using mobile lab, spatial distributions of chemical properties, including pH, organic matter (OM), total nitrogen (N), available phosphorus (as P2O5), and available potassium (as K2O) were examined in soil samples taken from the 0 to 15 cm depth from selected agricultural fields in eight different districts in the mid-hills and Terai regions of Nepal. Tests conducted on 1,479 soil samples in the soil-testing mobile van revealed the following: the mean soil OM ranged from 0.01 to 1.77%; total N content ranged from 0.01 to 0.08%; mean available P2O5 ranged from 16.47 to 197.82 kg ha−1; and mean available K2O ranged from 84.3 to 422.57 kg ha−1. For each crop to be grown, farmers were provided with individual soil health reports and fertilizer recommendations (rate, amount, and type). This program not only allows scientists and farmers to work closely and share information but also serves as a model for the nation to successfully transfer technology for improving soil health and sustainability

Improving fertilizer recommendations for Nepalese farmers with the help of soil-testing mobile van

Smallholder farmers dominate agriculture in Nepal. These farmers have poor knowledge about agriculture and lack of support for soil management and integrated plant-nutrient systems. Focusing on the importance and need for soil-fertility management, a soil-testing mobile van program has recently been introduced in Nepal by Soil Management Directorate, Hariharbhawan. With the introduction of the mobile lab, famers can get their soil tested for nutrient deficiencies and fertilizer requirements at their doorsteps. Using mobile lab, spatial distributions of chemical properties, including pH, organic matter (OM), total nitrogen (N), available phosphorus (as P2O5), and available potassium (as K2O) were examined in soil samples taken from the 0 to 15 cm depth from selected agricultural fields in eight different districts in the mid-hills and Terai regions of Nepal. Tests conducted on 1,479 soil samples in the soil-testing mobile van revealed the following: the mean soil OM ranged from 0.01 to 1.77%; total N content ranged from 0.01 to 0.08%; mean available P2O5 ranged from 16.47 to 197.82 kg ha−1; and mean available K2O ranged from 84.3 to 422.57 kg ha−1. For each crop to be grown, farmers were provided with individual soil health reports and fertilizer recommendations (rate, amount, and type). This program not only allows scientists and farmers to work closely and share information but also serves as a model for the nation to successfully transfer technology for improving soil health and sustainability