Outer rotor wound field flux switching machine for In-wheel direct drive application

Nowadays the flux switching machines offer pivotal role in high speed applications. The flux sources (field excitation coil and armature winding or permanent magnet) are confined to the stator leaving rotor completely passive, and thus making the flux switching machine (FSM) more suitable for industrial applications. This paper emphasizes salient rotor pole and non-overlapping windings embedded in electrical machine design possess some pertinent features such as reduced copper losses, low-cost, and usage in high speed applications. The proposed design is analyzed for coil test analysis and flux linkage and torque. On the basis of the analysis performed, it is clear that 12-slot/13-pole has low cogging torque, high flux linkage, and maximum torque, compared with other topologies of outer rotor field excitation FSM. A deterministic optimization technique is adopted to enhance the performance of 12-slot/13-pole design. Further, finite element analysis (FEA) results are verified through Global Reluctance Network (GRN) methodology, which show close resemblance with error less than 1.2%. Hence, it validates the proposed design for outer rotor field excitation FSM direct drive application. The proposed design for hybrid electric vehicle torque characteristic is compared with existing interior permanent magnet synchronous machine (IPMSM) and 6-slot/7-pole wound field flux switching machine (WFFSM)

Comparative analyses of residential building efficiency for AC and DC distribution networks

The escalating prevalence of rooftop solar PVs and DC powered home appliances are the driving forces for the research in the field of DC distribution at residential level. The current research work presents comparative analyses of AC and DC distribution systems considering various scenarios for the specific purpose of efficiency/energy savings. A modern Bakersfield CA, USA home is considered for the analyses. The loads are classified according to the power demand. Rooftop solar PVs are also included in each residential building. Mathematical equations are devised for the efficiency analysis of residential buildings powered with AC as well as DC. The results reveal strong dependence of the efficiency values on the utilization/types of loads, efficiencies of the power electronic converters (PECs), solar capacity and seasonal conditions, as a function of the time of day. It is concluded that AC system presents better efficiency values as compared to the DC counterpart except during the time periods when solar power is available and when the penetration of variable speed drive (VSD) based loads is high

An appraisal of precipitation distribution in the high-altitude catchments of the Indus basin

Scarcity of in-situ observations coupled with high orographic influences has prevented a comprehensive assessment of precipitation distribution in the high-altitude catchments of Indus basin. Available data are generally fragmented and scattered with different organizations and mostly cover the valleys. Here, we combine most of the available station data with the indirect precipitation estimates the accumulation zones of major glaciers to analyse altitudinal dependency of precipitation in the high-altitude Indus basin. The available observations signified the importance of orography in each sub-hydrological basin but could not infer an accurate distribution of precipitation with altitude. We used Kriging with External Drift (KED) interpolation scheme with elevation as a predictor to appraise spatiotemporal distribution of mean monthly, seasonal and annual precipitation for the period of 1998-2012. The KED-based annual precipitation estimates are verified by the corresponding basin-wide observed specific runoffs, which show good agreement. In contrast to earlier studies, our estimates reveal substantially higher precipitation in most of the sub-basins indicating two distinct rainfall maxima; 1st along southern and lower most slopes of Chenab, Jhelum, Indus main and Swat basins, and 2nd around north-west corner of Shyok basin in the central Karakoram. The study demonstrated that the selected gridded precipitating products covering this region are prone to significant errors. In terms of quantitative estimates, ERA-Interim is relatively close to the observations followed by WFDEI and TRMM, while APHRODITE gives highly underestimated precipitation estimates in the study area Basin-wide seasonal and annual correction factors introduced for each gridded dataset can be useful for lumped hydrological modelling studies, while the estimated precipitation distribution can serve as a basis for bias correction of any gridded precipitation products for the study area

Deep Learning Based Classification of Unsegmented Phonocardiogram Spectrograms Leveraging Transfer Learning

Cardiovascular diseases (CVDs) are the main cause of deaths all over the world. Heart murmurs are the most common abnormalities detected during the auscultation process. The two widely used publicly available phonocardiogram (PCG) datasets are from the PhysioNet/CinC (2016) and PASCAL (2011) challenges. The datasets are significantly different in terms of the tools used for data acquisition, clinical protocols, digital storages and signal qualities, making it challenging to process and analyze. In this work, we have used short-time Fourier transform (STFT) based spectrograms to learn the representative patterns of the normal and abnormal PCG signals. Spectrograms generated from both the datasets are utilized to perform three different studies: (i) train, validate and test different variants of convolutional neural network (CNN) models with PhysioNet dataset, (ii) train, validate and test the best performing CNN structure on combined PhysioNet-PASCAL dataset and (iii) finally, transfer learning technique is employed to train the best performing pre-trained network from the first study with PASCAL dataset. We propose a novel, less complex and relatively light custom CNN model for the classification of PhysioNet, combined and PASCAL datasets. The first study achieves an accuracy, sensitivity, specificity, precision and F1 score of 95.4%, 96.3%, 92.4%, 97.6% and 96.98% respectively while the second study shows accuracy, sensitivity, specificity, precision and F1 score of 94.2%, 95.5%, 90.3%, 96.8% and 96.1% respectively. Finally, the third study shows a precision of 98.29% on the noisy PASCAL dataset with transfer learning approach. All the three proposed approaches outperform most of the recent competing studies by achieving comparatively high classification accuracy and precision, which make them suitable for screening CVDs using PCG signals

Design and analysis of a photonic crystal based planar antenna for thz applications

Modern advancements in wearable smart devices and ultra-high-speed terahertz (THz) communication systems require low cost, low profile, and highly efficient antenna design with high directionality to address the propagation loss at the THz range. For this purpose, a novel shape, high gain antenna for THz frequency range applications is presented in this work. The proposed antenna is based on a photonic bandgap (PBG)-based crystal polyimide substrate which gives optimum performance in terms of gain (9.45 dB), directivity (9.99 dBi), and highly satisfactory VSWR (<1) at 0.63 THz. The performance of the antenna is studied on PBGs of different geometrical configurations and the results are compared with the antenna based on the homogeneous polyimide-based substrate. The effects of variations in the dimensions of the PBG unit cells are also studied to achieve a -10 dB bandwidth of 28.97 GHz (0.616 to 0.64 THz)

Course Contents of English Language Textbooks and their Relevance to Learners’ Culture in an Islamic Context

The study is an attempt at analyzing the cultural authenticity of the course contents of English as a foreign language at International Islamic University Islamabad. This study assumes that these course contents increase cultural barriers for the learners who belong to a different set of cultural values and religious and educational background. It traces the limitation of foreign textbooks writers because of their unawareness of the local culture and the social, educational and religious environment. The study on the one hand questions the suitability of such textbooks for the learners (mostly from religious institutions) and on the other hand gives proposals for the development of English textbooks based on indigenous or Islamic culture. Usually, the evaluation of course contents is descriptive in nature and is done to describe or find out a problem rather than to address it. To bring an improvement in course contents is the basic goal of course evaluation. Although, it would be irrelevant to manipulate a problem statement for this type of research yet ignoring the student factor in writing English text books and selecting these books without doing a prior research into the needs analysis of the learners can be cited as the main problem which inspired the study. This study adopts both a descriptive as well as a prescriptive approach. It analyses the contents to see what is there in the contents and what is required for the learners from a cultural perspective. On the basis of its two fold description the study has given suggestions as to what should be an ideal situation for the selection, adaptation and development of English language textbooks for the learners. The main hypothesis of the study was that there was no cultural relevance between the objectives of the learners for learning English, their social and educational background and the contents of the course book. The inappropriateness of the theories that advocate the inclusion of target language culture in language courses as an essential factor for teaching and learning English in every situation and for all learners is the secondary hypothesis of the study. The study has narrowed down its focus to the cultural relevance of the course contents being taught at the IIUI, the communication gap between the authors and the target learners, and to give suggestions regarding the possibility to include the learners’ culture in English language courses.   The study adopts a first glance evaluation in the light of guidelines provided by pedagogical theorists and deliberately avoids learners’ response method (in which learners responses are measured) because of the   researcher’s own interest in the impressionistic evaluation. The main purpose of the study was to bring the learners in the lime light of focus to make teaching of English more learners’ centered, to create awareness among the teachers, policy makers and course designers to consider learners needs in the process of textbooks selection and development. The study proves that the themes, setting, characters and worldview, presented in the contents of the book represent a foreign and unfamiliar world for the learners. The study suggests that the learners would be more motivated to learn English if language were presented in the context with which the learners could identify themselves. Keywords: language, English, Culture, Textbooks, Learner

Fluoroquinolone and macrolide co-resistance in clinical isolates of campylobacter species: a 15-year study in Karachi, Pakistan

Fluoroquinolone and macrolide antibiotics are generally considered as first-line drugs for the treatment of severe campylobacteriosis. This study was conducted to analyse the trend of erythromycin and ofloxacin resistance among Campylobacter spp. isolated from stool specimens over a period of 15 years (1992-2007) at The Aga Khan University clinical laboratory in Karachi, Pakistan. A total of 83 396 stool specimens were processed, with a 14% isolation rate for enteric pathogens. The isolation rate of Campylobacter spp. was low during 1992-93 (6%-13%), peaked in 1996 (46%), then ranged from 20% to 40%. We report a rising trend in ofloxacin resistance, re-emergence of erythromycin resistance and indications of co-resistance to both drugs in clinical isolates of Campylobacter spp

Residual Stresses in Alloy IN718 Produced through Modulated Laser Powder Bed Fusion

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Residual Stresses in Alloy IN718 Produced Through Modulated Laser Powder Bed Fusion

Background: Laser powder bed fusion (L-PBF) additive manufacturing (AM) is used for building metallic parts layer-by-layer and often generates non-uniform thermal gradients between layers during fabrication, resulting in the development of residual stresses when parts are cooled down. Objective: The impact of modulated laser used during the L-PBF process on residual stresses in Inconel 718 (IN718) material was investigated. The impact of build directions on residual stress is also determined. Methods: The contour method is employed to measure the full-field residual stress component on the cross-section of samples. A complementary residual stress measurement method, incremental hole drilling, was employed for obtaining in-plane residual stress components. Results: The results show that the residual stress distribution is sensitive to the build direction, with a higher magnitude of residual stress in the direction of build than that in the transverse direction. Multiple measurements with the same manufacturing parameters show good repeatability. Conclusion: Residual stresses in the as-built parts are significant and hence a further consideration regarding relieving residual stresses is required when post-thermal treatments are developed

Analysis of a Mathematical Model of Emerging Infectious Disease Leading to Amphibian Decline

We formulate a three-dimensional deterministic model of amphibian larvae population to investigate the cause of extinction due to the infectious disease. The larvae population of the model is subdivided into two classes, exposed and unexposed, depending on their vulnerability to disease. Reproduction ratio ℛ0 has been calculated and we have shown that if ℛ01, we discussed different scenarios under which an infected population can survive or be eliminated using stability and persistence analysis. Finally, we also used Hopf bifurcation analysis to study the stability of periodic solutions