Advances in Electron Beam Melting of Aluminum Alloys

The high thermal conductivity and melt pool optical reflectivity associated with aluminum alloys can pose significant challenges for direct-metal SFF processes. The use of SFF processes to produce aluminum parts is often not cost effective relative to CNC machining for simple geometries. However, the use of SFF techniques for aluminum alloys is justified for some applications such as aerospace forgings or high surface area heat exchangers. This paper describes recent progress in processing aluminum alloys using the Electron Beam Melting process. Structure and properties will be discussed, as well challenges associated with high vapor pressure alloying elements such as zinc and magnesium.Mechanical Engineerin

Measuring hearing protection performance results in a MIRE-compliant reverberatory chamber versus a non-MIRE compliant room

Noise Reduction Rating (NRR) is a method developed by the Environmental Protection Agency (EPA) to determine the effectiveness of hearing protection devices (HPD). The limitations of NRR values have led to use of other methods, including fit-testing hearing protectors on the individuals who will use them. The fit-testing method used in this study is the Microphone in Real Ear (MIRE) method, which describes how to test earmuffs in a reverberatory chamber. A reverberatory chamber is extremely costly and not likely to be available at work-sites. If fit-testing could be completed in any room instead of in a reverberatory chamber, work-sites could save on the cost of the chamber and may be more likely to fit-test hearing protectors.;In this study, the MIRE method was used. Both Noise Reduction (NR) and Insertion Loss (IL) were determined for nine subjects, both in an ordinary room and in a reverberatory chamber. Subjects were tested while wearing earmuffs and earplugs at different times. Results showed minor deviations in values between the reverberatory chamber and ordinary room when averaged from 125 Hz to 8000 Hz for each given subject and condition. The orientation of subjects affected observed NR and IL by less than 5 dB

Prevalence of congenital abnormalities on routine ultrasound scan of second and third trimester pregnancy

Background: Objective of the study was to evaluate the antenatal prevalence of major congenital abnormalities and its pattern.Methods: This is a cross-sectional study carried out in the department of ‘Radiology’ at ‘Fakhruddin Ali Ahmed Medical College and Hospital’, Barpeta. Patients in the 2nd and 3rd trimester of pregnancy, referred to ‘Radiology’ department from the outpatient and inpatient departments of ‘Obstetrics and Gynaecology’ were included in the study. Antenatal ultrasound findings were statistically analyzed on structured data collection form.Results: Total 2650 numbers of 2nd and 3rd trimester prenatal ultrasonography (USG) were done. Out of these 45 numbers of congenital anomalies were detected. The antenatal prevalence of congenital anomalies was 1.73%. The mean maternal age and mean gestational age at diagnosis was 25.5 years (SD ± 6.15) and 27 weeks (SD±6.42) respectively. Central nervous system (CNS) defect was the commonest (42%), of which maximum number had anencephaly defect i.e. 8 (17.78%) cases.Conclusions: Antenatal ultrasound is a non–invasive highly sensitive, accurate and cost effective imaging technique which gives good results in experienced hands. It is recommended that the obstetricians should advise regular USG at least at 2nd trimester

Factores que afectan a la floración de algas en lagos de gran altitud a baja latitud: una revisión y el caso de la bahía de Puno (Lago Titicaca, Perú)

Para facilitar la comprensión de factores que determinan la proliferación de algas en lagos, se compararon cuatro regiones: baja latitud y baja altitud; baja latitud y elevada altitud; latitud media y baja altitud; latitud media y elevada altitud. La influencia de la altitud en el clima fue más notable en las latitudes bajas que en las regiones de latitud media. Las actividades antropogénicas (escorrentía agrícola, turismo, vertido de aguas residuales con escaso o nulo tratamiento) en un lago a elevada altitud y su cuenca tienen mayor influencia que su posición dentro de la red hidrológica sobre su estado trófico. Se analizó información de parámetros de calidad de agua en la bahía de Puno (lago a elevada altura y baja latitud). El intercambio limitado entre la Bahía Interior de Puno (BIP) y la Bahía Exterior de Puno (BEP) junto con una mayor carga externa de nutrientes para la BIP que para la BEP parece explicar los valores de los parámetros de calidad del agua para la BEP significativamente más altos. Asimismo, la conexión de la BEP con el Lago Mayor podría estar facilitando la dilución de nutrientes en la BEP.Algal blooms are an increasing threat to lakes worldwide. This phenomenon has been studied worldwide but still a better understanding is needed of how algal bloom driving factors are affected by low-latitude and high-altitude conditions. Four regions were compared: Lakes at low-latitude and low-altitude; low-latitude and high-altitude; mid-latitude and low-altitude; and, mid-latitude and high-altitude. The influence of altitude in determining climate was more noticeable for low latitudes than for mid-latitude regions. For the deeper areas of a low-latitude lake, the latitudinal influence seems to be more relevant, as those lakes have a more stable stratification throughout the year. Anthropogenic activities (agriculture runoff, sewage discharge with low or no treatment and tourism) in the lake and its basin have a higher influence than the lake’s position within the hydrological network on the trophic status of high altitude lakes. Water quality parameters were analysed in Puno Bay, as an example of high altitude lake at low latitude. The increasing trend of parameters related to turbidity in Inner Puno Bay seemed to indicate the shift to a more turbid state for this area of Puno Bay. The limited exchange between Inner Puno Bay (IPB) and Outer Puno Bay (OPB) along with a higher external loading of nutrients for IPB than for OPB may play a role for IPB to have significantly higher values of water quality parameters. As IPB is a shallow water body, it is more exposed to the effect of the wind and the effect of daily temperature variation. Moreover, the connection of OPB with Lago Mayor may also enhance the mixing and the dilution of nutrients in OPB.Países Bajos. Orange Knowledge Program (OKP

Histopathological pattern of endometrium in abnormal uterine bleeding of perimenopausal women

Background: The aim of the study was to evaluate the histopathological pattern of endometrium in perimenopausal women presenting with abnormal uterine bleeding.Methods: This prospective study was carried out from June 2014 to May 2015 in a tertiary care teaching hospital on 180 number of perimenopausal women who presented with abnormal uterine bleeding.Results: Most of the patients were between 40-45 years of age (63.89%) and menorrhagia was the dominant clinical presentation 80 (44.44%). The commonest pathology was hyperplasia in 83 (46.11%) women with simple hyperplasia without atypia being the predominant pattern (65 cases) which was most commonly seen between 40 and 45 years of age. Atrophic endometrium was the common pattern in age group of ˃ 50 years. Other pathology identified were proliferative endometrium (20.56%), secretory endometrium (16.11%), endometritis (2.22%), endometrial polyp (2.22%), pregnancy related (2.22%) and carcinoma (1.11%).Conclusions: Histopathological pattern of the endometrium in abnormal uterine bleeding in perimenopausal women should be studied especially to rule out preneoplasia and malignancy

Harmonic mitigation and power quality improvement in utility grid with solar energy penetration using distribution static compensator

Abstract Distribution static compensator is based on power electronic devices technology which is utilized to supply rapid changes in active power as well as reactive power of utility grids. This is useful to achieve corrections in power factor, balancing of load, compensation of current and filtering of harmonics. Therefore, proposed work investigates the improvement of the power quality by utilizing the distribution static compensator, which is equipped by battery energy storage system and interfaced to distribution network with solar photo voltaic (PV) energy integration. In the present study, distribution static compensator is controlled using a control strategy based on the synchronous reference frame theory. Customised IEEE‐13 nodes test system incorporating solar PV generation and distribution static compensator, is utilized to perform the harmonic mitigation and power quality analysis. Disturbances of power quality and harmonics have been investigated due to abrupt changes in the insolation of solar radiation, outage of PV plant from grid and synchronization of PV plant to grid. MATLAB/Simulink environment is utilized to perform the study. Effectiveness of a developed approach is validated by comparing results of simulation with results extracted in real time using real time digital simulator. Results indicate that the developed method is more effective for harmonic mitigation and improving power quality of electrical power in distribution network integrated with solar PV generation. Performance of the approach is compared with the performance of methods reported in the literature to establish the suitability of the method for harmonics mitigation and power quality improvement in grid with solar energy