A prospective comparative study of internal fixation of diaphyseal forearm fractures with LCP and DCP in above 50 year age group

Background: In orthopedic practice forearm bone fracture is commonly encountered fracture. Forearm plays a vital role in day to day activities without which a person is unable to perform his role in his own life. It has been estimated that around 31% of the total fractures of the upper limb are of forearm fractures. The objective of the study was to study and compare internal fixation of diaphyseal forearm fractures with LCP and DCP in above 50 year age groupMethods: Present study was hospital based study. This was a prospective study. A total of 50 patients with fracture of both bones in the forearm were included in the present study. They were divided randomly as 25 patients in each group. They were followed for about eight months.Results: Both the groups in the present study were found to be comparable in terms of age, sex, mode of injury, type of injury and level of fracture. It took only 13.83 weeks for radiological union in LCP group and it took a longer in DCP group of 15.33 weeks. This difference was found to be statistically significant. Overall functional results were almost same in both the groups. Excellent in 36 cases (19 in LCP, 17 in DCP), Good in 10 cases (4 in LCP, 6 in DCP), fair in 4 cases (2 in each group).Conclusions: It has been concluded from the present study that union of fracture after LCP had taken significantly lesser time as compared to the DCP technique. Hence especially in persons above 50 years, LCP should be used

Space Vector Based Hybrid Random PWM Algorithm for DTC-IM Drive To Achieve Superior Waveform Quality

This paper presents a simplified space vector based hybrid random pulsewidth modulation algorithm for direct torque controlled induction motor drive to achieve superior waveform quality and reduced acoustical noise and harmonic distortion. To reduce the complexity involved in the conventional space vector approach, the proposed pulsewidth modulation (PWM) algorithm uses instantaneous sampled reference phase voltages to calculate the actual switching times of the devices. The proposed PWM algorithm modifies the time duration of application of vector V0 (000) by using a factor. By changing the value of this factor many switching sequences can be derived. The proposed PWM algorithm uses 0127, 012 and 721 switching sequences when value takes 0.5, 1 and 0 respectively. In order to achieve superior waveform quality, the harmonic analysis of these sequences is carried out using the notion of stator flux ripple and expressions are derived for mean square flux ripple in terms of imaginary switching times and modulation index. By comparing the instantaneous ripple values in each sampling time interval, the suitable sequence is selected that results in minimum current ripple. Thus, the proposed algorithm gives reduced harmonic distortion when compared with the SVPWM algorithm. As the zero state time is varied randomly according to the operating sequence, randomization effect will occur, which results in reduced dominating harmonics and hence acoustical noise when compared with the SVPWM algorithm. The simulation results validate the proposed algorithm

Space Vector Based Dual Zero-Vector Random Centered Distribution Pwm Algorithm for Direct Torque Control of Induction Motor Drive For Reduced Acoustical Noise

The direct torque control (DTC) technique has been recognized as the viable solution to achieve precise and quick torque response but it suffers from few drawbacks such as high ripple in torque, flux and stator current resulting in increased vibrations and acoustic noise. The conventional SVPWM algorithm gives good performance for control of induction motor drive, but it also produces considerable acoustical noise resulting in increased total harmonics distortion. The deterministic pulse width-modulation (PWM) method adopted in induction-motor drives causes Acoustical noise due to the switching frequency. This paper presents a novel dual zero-vector random centered distribution PWM algorithm for direct torque controlled induction motor drive. The proposed PWM algorithm uses two zero voltage vectors. When the operating modulation index is less than the critical modulation index, the proposed PWM algorithm uses V0 (000) as zero voltage vector. Otherwise, when the operating modulation index is greater than the critical modulation index, the proposed PWM algorithm uses V7 (111) as zero voltage vector. To verify the proposed PWM algorithm, a numerical simulation studies have been carried out and results are presented and compared with classical SVPWM algorithm. The simulation results confirm the effectiveness of the proposed DZRCDPWM algorithm for the considered drive. Key words: DTC, DZRCDPWM, RPWM, SVPWM, Acoustic noise

Random Zero Vector Distribution PWM Algorithm for Direct Torque Control of Induction Motor Drive for Noise Reduction

The basic direct torque control algorithm gives large ripples in torque, flux and current in steady state, which results in acoustical noise and incorrect speed estimations. The conventional SVPWM algorithm gives good performance for control of induction motor drive, but it produces more acoustical noise resulting in increased total harmonics distortion. The random pulse width modulation (RPWM) techniques have become an established means for mitigation of undesirable side effects in adjustable speed ac drives in particular. Hence, to minimize these anomalies of the drive, this paper presents a random zero vector distribution (RZVDPWM) algorithm for direct torque controlled induction motor drive. The proposed random zero vector distribution PWM (RZVDPWM) algorithm distributes the zero state time between the two zero voltage vectors. To validate the proposed PWM algorithm, simulation studies have been carried out and results are presented and compared. From the results, it can be observed that the proposed RZVDPWM algorithm gives reduced acoustical noise when compared with space vector pulse width modulation (SVPWM) algorithm

Selantes vítreos e vitrocerâmicos à base de aluminosilicatos alcalino-terrosos para aplicações funcionais

Doutoramento em Ciência e Engenharia dos MateriaisThe planar design of solid oxide fuel cell (SOFC) is the most promising one due to its easier fabrication, improved performance and relatively high power density. In planar SOFCs and other solid-electrolyte devices, gas-tight seals must be formed along the edges of each cell and between the stack and gas manifolds. Glass and glass-ceramic (GC), in particular alkaline-earth alumino silicate based glasses and GCs, are becoming the most promising materials for gas-tight sealing applications in SOFCs. Besides the development of new glass-based materials, new additional concepts are required to overcome the challenges being faced by the currently existing sealant technology. The present work deals with the development of glasses- and GCs-based materials to be used as a sealants for SOFCs and other electrochemical functional applications. In this pursuit, various glasses and GCs in the field of diopside crystalline materials have been synthesized and characterized by a wide array of techniques. All the glasses were prepared by melt-quenching technique while GCs were produced by sintering of glass powder compacts at the temperature ranges from 800−900 ºC for 1−1000 h. Furthermore, the influence of various ionic substitutions, especially SrO for CaO, and Ln2O3 (Ln=La, Nd, Gd, and Yb), for MgO + SiO2 in Al-containing diopside on the structure, sintering and crystallization behaviour of glasses and properties of resultant GCs has been investigated, in relevance with final application as sealants in SOFC. From the results obtained in the study of diopside-based glasses, a bilayered concept of GC sealant is proposed to overcome the challenges being faced by (SOFCs). The systems designated as Gd−0.3 (in mol%: 20.62MgO−18.05CaO−7.74SrO−46.40SiO2−1.29Al2O3 − 2.04 B2O3−3.87Gd2O3) and Sr−0.3 (in mol%: 24.54 MgO−14.73 CaO−7.36 SrO−0.55 BaO−47.73 SiO2−1.23 Al2O3−1.23 La2O3−1.79 B2O3−0.84 NiO) have been utilized to realize the bi-layer concept. Both GCs exhibit similar thermal properties, while differing in their amorphous fractions, revealed excellent thermal stability along a period of 1,000 h. They also bonded well to the metallic interconnect (Crofer22APU) and 8 mol% yttrium stabilized zirconium (8YSZ) ceramic electrolyte without forming undesirable interfacial layers at the joints of SOFC components and GC. Two separated layers composed of glasses (Gd−0.3 and Sr−0.3) were prepared and deposited onto interconnect materials using a tape casting approach. The bi-layered GC showed good wetting and bonding ability to Crofer22APU plate, suitable thermal expansion coefficient (9.7–11.1 × 10–6 K−1), mechanical reliability, high electrical resistivity, and strong adhesion to the SOFC componets. All these features confirm the good suitability of the investigated bi-layered sealant system for SOFC applications.A concepção planar de células de combustível de óxido sólido (SOFC) é a mais promissora devido a sua fabricação mais fácil, um melhor desempenho e uma densidade de potência relativamente elevada. Nas SOFCs planares e outros dispositivos de electrólitos sólidos são necessárias vedações estanques ao gás ao longo das arestas de cada uma das células e entre os tubos de distribuição de gás e de pilha. Materiais vítreos e vitrocerâmicos (GC), em particular com composições baseadas em aluminosilicatos alcalino-terrosos, estão entre os materiais mais promissores para aplicações de vedação à prova de gás em SOFCs. Além do desenvolvimento de novos materiais à base de vidros e vitrocerâmicos, são também necessários novos conceitos para superar os desafios enfrentados pela tecnologia selante atualmente existente. O presente trabalho visa dar um contributo nesse sentido, propondo soluções de vedação para SOFCs e outras aplicações electroquímicas. Para o efeito, foram sintetizados vários vidros e GCs à base de diópsido, os quais foram caracterizados por recurso a uma grande variedade de técnicas. Todos os vidros foram preparados por fusão, enquanto os GCs foram produzidos por sinterização (tratamento térmico) de compactos de pó de vidro nas faixas de temperatura de 800 − 900 ºC por 1 − 1000 h. Além disso, foram estudados os efeitos de diversas substituições iónicas, especialmente de CaO por SrO, e de MgO + SiO2 por Ln2O3 (Ln = La, Nd, Gd, e Yb), em composições de aluminosilicatos à base de diópsido na estrutura, sinterização e cristalização dos vidros e nas propriedades dos GCs resultantes com particular relevância para as propriedades de vedação em SOFCs. Com base nos resultados obtidos neste estudo, foi possível propor um novo conceito de selante vritrocerâmico em bi-camadas que visa ultrapassar os desafios enfrentados pelos vedantes actualmente usados em SOFCs. Os sistemas designados por Gd−0,3 (em % molar: 20,62 MgO−18,05 CaO−7,74 SrO−46,40 SiO2−1,29 Al2O3−2,04 B2O3−3,87 Gd2O3) e Sr−0,3 (em % molar: 24,54 MgO−14,73 CaO−7,36 SrO−0,55 BaO−47,73 SiO2−1,23 Al2O3−1,23 La2O3−1,79 B2O3−0,84 NiO) foram seleccionados para realizar o conceito de bi-camada. Ambos os GCs exibem propriedades térmicas semelhantes, e excelente estabilidade térmica ao longo de um período de 1.000 horas, mas diferem nas suas fracções vítreas/cristalinas. Eles revelaram também elevada aptidão para se ligarem à interconexão metálica (Crofer22APU) e ao electrólito sólido (zircónia estabilizada com 8 mol% de ítria (8YSZ) sem a formação de camadas interfaciais indesejáveis entre os diferentes componentes das SOFCs. Duas camadas separadas compostas pelos vidros (Gd−0,3 e Sr−0.3) foram preparadas e depositadas sobre as interconexões metálicas através de uma abordagem tape casting. As bi-camadas vitrocerâmicas mostram boa capacidade de molhamento e ligação à placa Crofer22APU, coeficientes de expansão térmica adequados (9,7−11,1 × 10−6 K−1), confiabilidade mecânica, elevada resistividade eléctrica, e uma forte adesão aos componentes da SOFC. Todas estas características confirmam a boa adequação do sistema selante bi-camadas investigado para aplicações em SOFCs

VOICE OVER LONG TERM EVOLUTION SERVICE QUALITY MEASUREMENTS AND DIAGNOSTICS USING MACHINE LEARNING TECHNIQUES

Techniques are described for a machine learning based Voice over Long Term Evolution (VoLTE) trouble-shooting/diagnostic approach which can look at various data sources in the mobile packet core and identify the key issues by observations and correlations across data fields using machine learning techniques. It helps mobile operators to quickly identify fault domains in VoLTE calls and take corrective actions to enhance customer Quality of Experience (QoE)

Clinical and functional outcomes of pre-contoured plate fixation in displaced intraarticular calcaneum fracture

Background: We evaluated the clinical and functional outcome of intra-articular calcaneal fractures treated with pre-contoured plating. The functional outcome was measured by the American Orthopaedic Foot and Ankle Society (AOFAS) scoring system.Methods: Twenty-five adult patients with displaced intra-articular calcaneus fractures, treated with by open reduction and internal fixation using pre-contoured plates, and those who were available for follow up were evaluated for the outcomes such as operative procedure, anatomical reduction, postoperative hospital stays early mobilization and functional outcome postoperatively. Follow-up was at three, six and twelve months radiological and clinical union were also considered.Results: Twenty-five adult patients presented with calcaneal fractures were operated during the study period. The mean time for union of fracture was 12.5±1.8 weeks. When we assessed the functional outcome in those patients who had radiological and clinical union using AOFAS score, we found that 16 out of 23 (64%) had good results with mean AOFAS score of 83.5±2.0 and 7/25 (28%) had fair results with mean score of 73.3±1.3, and 2/25 (8%) had poor results with mean score of 54.0±8.5. In 2 out of 16 (12.5%) patients, with good AOFAS scores, implants were removed after one and a half year from the day of surgery after confirming complete union of the fracture.Conclusions: We believe that pre-contoured reconstruction plate fixation for displaced intraarticular calcaneus fracture is excellent in terms of the union of the fracture, attaining anatomical reduction. It gives better outcomes concerning the function and range of movements

Role of volar plating in unstable distal radial fractures in elderly patients in tertiary teaching hospital

Background: Aim of the study was to investigate the efficacy of volar locking plate fixation for unstable distal radical fractures DRFs in the elderly population (60 years old and older).Methods: An ethical committee approved the study protocol for research studies at NRI medical college. We included only unstable distal radial fractures in elderly patients between 60 to 70 years, and patients who consent to the study. We excluded patients with comorbid conditions and below 60 years and patients with vascular injuries. Results were evaluated by the DASH questionnaire and Gartland and Werley scores.Results: According to Gartland and Werley score, 30 patients (85.7%) had excellent and good results. According to the DASH score, 31 patients (88.5%) had excellent and good results, and four patients (11.4%) had fair results. The most commonly noted complications in our study were arthritis (2 cases 5.7%), extensor pollicis longus tendon irritation (1 case 2.9%), and Reflex sympathetic dystrophy (1 case 2.9 %).Conclusions: Locked compression plate in unstable distal radius fractures provides excellent results with an effective correction of distal radius anatomy. Early range of movements of joints leads to a good outcome and return to regular activity.