An ordinal optimization based method for power distribution system control

This work presents an Ordinal Optimization Theory based method for power distribution system control. The solution procedure bases on an evolutionary search scheme. The method aims at minimizing the total power losses on network feeders while keeping the node voltages at near rated values against changing loading conditions. By relaxing the definition of optimality and softening the goal of optimization, ordinal optimization makes the problem easier as well as the solution process faster. A solution can be defined as good enough in performance value if it is one of the best m-percent solutions on the search space with probability P%. A solution can be defined as good enough also if its performance value approximates to the optimal value to a pre-defined extent. This work estimates the performance value. the total power loss, of the optimum state of power distribution network at a given loading condition. Then, with the two relaxed definitions for optimality. it finds the optimal settings of on-load tap changers and capacitors in a 24-h time frame. Results verify our method is proper for on-line and off-line operation. (C) 2007 Elsevier B.V. All rights reserved

Energy management of solar car in circuit race

This study develops an optimal driving strategy for solar car on a track with nonzero gradients and sharp corners. This strategy consists of finding the racing line and the speed profile that minimizes the lap time with a given amount of energy. The problem is formulated in proper form for a commercial nonlinear optimization software program. The track is modeled into segments identified by their spatial coordinates on its own surface. The speed-distance behavior of the vehicle is linearized at each segment. The constraints set by the brushless DC motor, battery, and circuit are formulated accordingly. This is the motor type widely used in electric cars. The solver produces both the positions of the car on the track and entry speeds into the segments, which minimizes the lap time for the given amount of the solar power and battery reserve. The positions of the car describe the best racing line. Formulation of the constraints allows extracting the motor current profile from the speed profile, which comprises the set of control actions. These profiles help the human driver identify where and how much to accelerate along the track for the desired performance of the car. The algorithm presented here can also serve as a tool to assess the performance of an electric car at different road conditions, thus helping to choose the best settings of the motor and the car

Using ordinal optimization approach in power distribution systems

This study investigates the applicability of ordinal optimization approach to optimal control of power distribution systems. This approach enables us searching for a solution good enough with high probability instead of the best for sure in solving those problems with huge search spaces. Power distribution system control is such a problem, to which a near-optimal solution can be found by evolutionary search techniques. In this study we calculated node voltages and power losses of a sample system corresponding to all possible OLTC settings and capacitor on/off statuses. We obtained these solutions exactly and approximately and investigated the coincidences between the best 1%, the best 5%, and the best 10% of these solutions correspondingly. Results show that based on approximately-calculated node voltages and power losses a near-optimal solution can still be found to power distribution system control problem by an evolutionary search technique with considerable saving in total computation time

Testing Ordinal Optimization approach in power distribution system control

This study presents an Ordinal Optimization based approach to the power distribution control problem. Primary task of the distribution control is the minimization of total power losses. Secondarily, it aims at keeping the bus voltages at acceptable values against different loading levels. Control operation is performed by capacitor switchings and on-load tap changer adjustments at substations. This operation involves a large search space with a considerable computational burden. Ordinal Optimization Theory presents proper tools in handling this burden. This theory reduces the size of the problem by defining the "good enough" subsetas the top-m% of the search space, which is obtained through a different procedure of ranking candidate solutions

The microbiological ınvestigation of superficial colonization on pressure ulcers of patients managed by home care service

Amaç: Bası yarası enfeksiyonlarının tanısında doku biyopsisi alınması önerilmekle birlikte, bu yöntem her zaman uygulanamamaktadır. Evde bakım uygulanan hastalarda, biyopsi almadan patojen mikroorganizma kolonizasyonunu takip etmenin yararlı olabileceği düşünülerek, bu hastaların bası yaralarından alınan yüzeyel örneklerin mikrobiyolojik olarak incelenmesi amaçlanmıştır. Gereç ve Yöntem: Kocaeli Belediyesi-Evde Bakım Hizmetleri Merkezi tarafından takip edilen 68 hastanın bası yaralarından alınan sürüntü örnekleri %5 koyun kanlı ve EMB agar plaklarına ekilmiştir. Üreyen bakterilerin tanımlanması ve antimikrobiyal duyarlılık testleri VITEK 2 (bioMérieux, Fransa) otomatize sistemi ile yapılmıştır. Bulgular: Bası yaralarının %34’ü evre II, %45’i evre III ve %21’i evre IV olarak belirlenmiştir. Örneklerin çoğu sakrum (%58) ve kalça (%20) bölgesinden alınmıştır. Üreyen bakterilerin %48’i nonfermentatif, %38’i enterik ve %14’ü gram pozitif bakterilerdir. En sık üreyen bakteriler sırasıyla Pseudomonas aeruginosa (n=23), Proteus spp. (n=20) ve Acinetobacter baumannii (n=18)’dir. Sonuç: Bası yarası enfeksiyonlarının tanısında altın standart yöntem olan derin doku kültürünün alınamadığı durumlarda, yüzeyel örneklerdeki kolonizasyonun değerlendirilmesi, tedavi endikasyonu olan hastalarda antibiyotik seçiminde yardımcı olabilir.Aim: Taking tissue biopsy is recommended in diagnosis of infected pressure ulcers, however this method cannot be applied in any case. Presuming that the observation of microorganisms colonisation instead of tissue biopsy would be more useful, the microbiological investigation of superficial samples from pressure ulcers of these patients was aimed. Material and Method: The swab samples from pressure ulcers of 68 patients followed by Kocaeli Municipality -Home care service were cultured onto 5% sheep blood and EMB agar. The identification of bacteria and antimicrobial susceptibility tests were determined by VITEK 2 (bioMérieux, Fransa) automatized system. Results: The ratio of grading of pressure ulcers were determined as: 34% grade II, 45% grade III and 21% grade IV. The swabs were taken mostly from sacrum (58%) and hip (20%) regions. The isolated bacteria were: 48% nonfermentatives, 38% enterics and 14% gram positive bacteria. The most common bacteria isolated were: Pseudomonas aeruginosa (n=23), Proteus spp. (n=20) and Acinetobacter baumannii (n=18). Conclusion: For the diagnosis of pressure ulcer infections, in cases that the gold standard method, deep tissue biopsy cannot be obtained, the evaluation of colonization in superficial samples may be useful in choosing the antibiotics in patients whom treatment is indicated

Can hyperbaric oxygen be used to prevent deep infections in neuro-muscular scoliosis surgery?

BACKGROUND: The prevalence of postoperative wound infection in patients with neuromuscular scoliosis surgery is significantly higher than that in patients with other spinal surgery. Hyperbaric oxygen has been used as a supplement to treat postsurgical infections. Our aim was to determine beneficiary effects of hyperbaric oxygen treatment in terms of prevention of postoperative deep infection in this specific group of patients in a retrospective study. METHODS: Forty two neuromuscular scoliosis cases, operated between 2006–2011 were retrospectively reviewed. Patients who had presence of scoliosis and/or kyphosis in addition to cerebral palsy or myelomeningocele, postoperative follow-up >1 year and posterior only surgery were the subjects of this study. Eighteen patients formed the Hyperbaric oxygen prophylaxis (P-HBO) group and 24, the control group. The P-HBO group received 30 sessions of HBO and standard antibiotic prophylaxis postoperative, and the control group (received standard antibiotic prophylaxis). RESULTS: In the P-HBO group of 18 patients, the etiology was cerebral palsy in 13 and myelomeningocele in 5 cases with a mean age of 16.7 (11–27 yrs). The average follow-up was 20.4 months (12–36mo). The etiology of patients in the control group was cerebral palsy in 17, and myelomeningocele in 7 cases. The average age was 15.3 years (8–32 yrs). The average follow-up was 38.7 months (18–66mo). The overall incidence of infection in the whole study group was 11.9% (5/42). The infection rate in the P-HBO and the control group were 5.5% (1/18), and 16.6% (4/24) respectively. The use of HBO was found to significantly decrease the incidence of postoperative infections in neuromuscular scoliosis patients. CONCLUSION: In this study we found that hyperbaric oxygen has a possibility to reduce the rate of post-surgical deep infections in complex spine deformity in high risk neuromuscular patients

Realization of SV-PWM Motor Control Algorithm using ARM Cortex-M4 Based Microcontroller

Space vector pulse width modulation (SV-PWM), which is the one of the sensorless control techniques of the permanent magnet AC motors, is preferred because it provides voltage and frequency control and produces less harmonics than the sinusoidal pulse width modulation (S-PWM) technique, respectively. In SV-PWM method; the fact that results of the complex equations should be performed in a given period of time by the microcontroller to calculate the required switching time, makes it difficult to implement algorithm in practice. This study includes the implementation of SV-PWM algorithm using ARM Cortex-M4 based microcontroller and experiments conducted on a motor