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Switched reluctance machine (SRM) has progressed as a suitable contender in the family of electrical machines for its high starting torque and better performance in different operating conditions. The need for accurate modeling of this machine is therefore dependent on the accurate determination of losses of which iron loss is exigent. This paper aims to determine iron loss from the equivalent circuit parameters of the machine based on the input data tables that are directly obtained from the experiments performed on an existing 4-phase, bifilar wound switched reluctance machine. The procedure and necessary steps for the loss separation method are well defined and supported by the theoretical and practical results. The experimental determination of the iron losses has been compared with the predicted results under the same operating conditions.

Objective: To introduce a relatively convenient and effective way of conducting Insulin Tolerance Test for diagnosis of Growth Hormone deficiency in children with short stature. Study Design: Cross sectional analytical study. Place and Duration of Study: Conducted at Department of Chemical Pathology and Endocrinology, Armed Forces Institute of Pathology, Rawalpindi, from May 2017 to Jul 2018. Methodology: A total of 185 cases were included. Sample selection was done by non-probability consecutive sampling technique. Insulin tolerance test was performed by taking basal sample for serum growth hormone and plasma glucose levels before giving intravenous insulin bolus according to dose of 0.15 IU/kg. Samples for Growth Hormone level were repeated at time of induced hypoglycemia (defined as plasma glucose level of 20 mIU/l) at induction alone, followed by 30 minutes post induction; reflecting the significance of these two samples in diagnosis of growth hormone deficiency. Conclusion: We concluded that there is a simpler ...........

Objective: To determine the diagnostic accuracy of immunoassays in drug screening as required in emergency for the rapid diagnosis of drug intoxication in travel related crimes. Study Design: Diagnostic accuracy study. Place and Duration of Study: department of Chemical Pathology and Endocrinology, Armed Forces Institute ofPathology, Rawalpindi Pakistan, from Jul 2017 to Jun 2018. Methodology: Sealed urine specimens of 77 patients with history of suspected intoxication in drugs facilitatedstreet crimes, received for toxicology screening were included in the study. All the specimens were analysed,initially on immunoassay (index test) and then on Triple Quadrupole Liquid chromatography–Mass spectrometry (reference standard). Benzodiazepine being the main class of drugs involved in travel related crimes, diagnostic accuracy of immunoassay technique was assessed for these by calculating its sensitivity, specificity, positive predictive value and negative predictive value. Results: Victims were predominantly males and public transportation was the most common mode of transport. The most commonly used drug was Lorazepam. Immunoassay failed to detect few cases who were shown to be intoxicated with benzodiazepines by liquid-chromatography tandem mass spectrometry. The false negative rate was 4.9%. Only one false positive case was observed. The accuracy was calculated to be 94.8% with sensitivity of 95.08% and specificity of 93.7%. Conclusion: Immunoassay was found reliable for rapid testing in drug facilitated intoxication cases. Howevercritical decision making should be done cautiously keeping in mind the limitations associated with thesescreening procedures.

The increasing popularity of the switched reluctance machine has created more challenges to present it as a good performer machine under different operational conditions. For modeling and simulation of the machine, the necessity of static characteristics, in particular, flux linkage characteristics which look like the base stone for initialization of simulation is unavoidable. The importance of flux linkage characteristics, and how other data tables such as inverter flux linkage characteristics, co energy and static torque table are obtained are presented in this work. This paper describes a set of equations for modeling of the flux linkage characteristics of switched reluctance machine and also hardware for the 3-phase machine is presented. Keywords: Flux Linkage Characteristics, Inductance Profile, Switched Reluctance Machine

The increasing environmental repercussions and depletion of nonrenewable energy resources have cautioned and enabled researchers to incorporate renewable energy systems. Amongst the renewable energy resources, the solar energy system has been utilized in most parts of the world due to cheaper, reliable, robust and sustainable energy resource than other resources. The Maximum Power Point Tracking (MPPT) techniques are used for increasing the power output of PV array. The Perturb and Observe (P&O) technique is widely used MPPT technique due to higher efficiency and ease in implementation. The proposed “Perturb and Observe (P&O)” MPPT technique is incorporated through Matlab Simulation software on PV arrays of various companies. The results are then compared through comparative analysis and optimum results are recommended for the manufacturing companies.

This paper proposes a novel brushless excitation topology for a three-phase synchronous machine based on a customary current-controlled voltage source inverter (VSI). The inverter employs a simple hysteresis-controller-based current control scheme that enables it to inject a three-phase armature current to the stator winding which contains a dc offset. This dc offset generates an additional air gap magneto-motive force (MMF). On the rotor side, an additional harmonic winding is mounted to harness the harmonic power from the air gap flux. Since a third harmonic flux is generated in this type of topology, the machine structure is also modified to accommodate the third harmonic rotor winding to have a voltage induced as the rotor rotates at synchronous speed. Specifically, four-pole armature and field winding patterns are used, whereas the harmonic winding is configured for a twelve-pole pattern. A diode rectifier is also mounted on the rotor between the harmonic and field windings. Therefore, the generated voltage on the harmonic winding feeds the current to the field winding for excitation. A 2D-finite element analysis (FEA) in JMAG-Designer was carried out for performance evaluation and verification of the topology. The simulation results are consistent with the proposed theory. The topology could reduce the cost and stator winding volume compared to a conventional brushless machine, with good potential for various applications. National Research Foundation of Korea | Ref. 2016R1D1A1B01008058 National Research Foundation of Korea | Ref. 2019H1D3A1A01102988 Korea government Ministry of Trade, Industry and Energy | Ref. 20204030200090

In the last few decades, wind energy has become a significant source of the renewable energy system, and it is essential to use wind energy for generating power and run the wind turbine system (WTs) at a higher level. With the rapid penetration of wind energy in the distributed generation system (DGS) and isolated micro-grid (MG), the WT runs at its optimal energy conversion output. For this, WT has to track or drive at the optimal power point tracking algorithm. However, various publications are available on MPPT algorithms for wind energy system (WES) applications, making a choice on exact trackers for a particular algorithm because each tracker has its advantages and disadvantages. Therefore, our primary goal is to review and evaluate the exact tracking algorithm for WES applications in this manuscript. To introduce the power controller, it is essential to track maximum power despite wind energy results. Besides, many algorithms have been evaluated, and their maximum output is achieved compared to their performance. This research paper will help researchers provide an accurate reference for future recommendations by selecting the best tracking algorithms in WES.

The significance of the modern fractional derivatives containing the singular kernel with locality and the non-singular kernel with non-locality have recently diverted the researchers because of the numerical or experimental analyses on the behavior between a system conservative and dissipative and the lack of fractionalized analytic methods. This study investigates the effects of modern fractional differentiation on the RLC electrical circuit via exact analytical approach. The modeling of governing differential equation of RLC electrical circuit has been fractionalized through three types of fractional derivatives namely Caputo, Caputo-Fabrizio and Atangana-Baleanu fractional derivatives based on the range as $$0 \le \alpha \le 1,\,\,0 \le \beta \le 1,\,\,0 \le \gamma \le 1$$ respectively. The RLC electrical circuit is observed for exponential, periodic and unit step sources via three classified modern fractional derivatives. The exact analytical solutions have been investigated by invoking mathematical Laplace transforms and presented in terms of convolutions product and special function namely Fox-H function. The Comparative mathematical analysis of RLC electrical circuit is based on Caputo, Caputo-Fabrizio and Atangana-Baleanu fractional derivatives which exhibit the presence of heterogeneities in the electrical components causing irreversible dissipative effects. Finally, the several similarities and differences for the periodic and exponential sources have been rectified on the basis of the Caputo, Caputo-Fabrizio and Atangana-Baleanu fractional derivatives for the current.

Objective To evaluate the effect of bilirubin interference on plasma amino acid analysis by Ion Exchange Chromatography (IEC). Study design Cross-sectional (method validation) study. Place and duration of study Department of Chemical Pathology and Endocrinology, Armed Forces Institute of Pathology, Rawalpindi from August 2016 to July 2017. Methodology Twenty non-icteric samples from paediatric patients were collected in lithium heparin tubes and analysed for amino acids on IEC-based Biochrome® 30+ Analyzer (Harvard Biosciences UK). Baseline bilirubin levels were noted. Samples were spiked with neonatal bilirubin standard with concentration of 488.4 mol/L (Spinreact®-Spain) at final concentrations of 50, 150 and 230 mol/L and re-analysed for amino acids at these three concentrations. Results Among the 20 selected patients with normal amino acid profiles, 12 (60%) were males. Majority (55%) were in age group of 1-5 years. Significant difference was observed for Arginine (p = 0.01), Histidine (p = 0.001), Isoleucine (p = 0.01), Leucine (p = 0.007), Lysine (p = 0.005), Ornithine (p = 0.03) and Phenylalanine (p = 0.02). Mean rank of these amino acids showed decreasing trend with the increase of bilirubin concentration, and pronounced interference was identified at bilirubin level of 50 mol/L. No difference was observed for alanine, citrulline, glutamic acid, glycine, methionine, proline, threonine, tyrosine, asparagine, aspartic acid, cystine, valine and tryptophan. Conclusion Bilirubin significantly interferes with certain amino acid levels when analysis is carried out by ion exchange chromatography. A close follow-up of such patients with other biochemical tests and a repeat amino acid analysis, after jaundice is settled, is recommended to confidently rule out any possible inherited metabolic disorder in these patients.

Adult growth hormone deficiency (AGHD) syndrome has a constellation of features, like impaired cognitive function, altered body composition, poor quality of life and various metabolic changes. Most of its features resemble signs of aging as growth hormone (GH) secretion decreases with age. Hypothalamic-pituitary-adrenal (HPA) axis should be thoroughly investigated in this disease as patients with AGHD are at risk of life-threatening consequences due to partial or complete ACTH deficiency, especially in stressful conditions. GH deficiency has also been related to diabetes or glucose intolerance. It is relatively underdiagnosed problem in adults and requires a thorough workup including dynamic function tests like insulin tolerance test (ITT), which has been termed as the gold standard for the diagnosis of patients with ACTH deficiency.

This study presents the optimization of algal biomass catalytic gasification for hydrogen-rich gas production. Three operating parameters under varying conditions of temperature (700–900 °C), catalyst loading (5–20 wt%) and reaction time (15–40 min) were optimized. The central composite design (CCD) was used to perform optimization and to investigate the influence of operating parameters on response variables (fractions of H2, CO, CO2 and CH4). The results indicated the temperature and catalyst loading as the most significant reaction parameters influencing H2 production and reducing the tar produced during the gasification process. The highest H2 fraction of 48.95 mol% (18.77 mol kg-biomass−1) was obtained at an optimum condition at 851 °C with catalyst loading of 16.4 wt% and reaction time of 28.8 min. The high R2 values of 0.98, 0.97, 0.95, and 0.90 corresponding to the response variables (H2, CO, CO2 and CH4) showed paramount estimation of model.

It is highly imperative to recover energy from not only the lipid fraction of microalgae but also the residual biomass after lipid-extraction to augment energy potential and to facilitate the sustainability of algal-based bioenergy. Herein, we present the production of syngas from microalgae residual biomass (Chlorella vulgaris), upon its extraction as by-product from biodiesel production system, in a lab-scale fixed bed reactor (FBR). The influences of two gasification parameters such as temperature (700, 800 and 900 °C) and catalysts type (Y2O3, Ni and eggshell derived CaO) have been studies in terms of CnHm/CO/H2 gas yield and composition, carbon conversion efficiency (CCE%), lower heating value (LHV) of syngas under 5% O2 and 95% Ar gasification environment. From the results, 800 °C was found to be an optimum temperature producing highest H2 yield (4.53 mmol g−1 biomass with purity of 34.62 vol%) and highest generation peak intensity of 0.14 mmol min−1 g−1, whereas highest LHV (8.92 MJ N m−3), total gas yield (73.54 wt%) and CCE (49.54%) were obtained at 900 °C. Addition of catalysts further improved H2 yield and its volume fraction, total gas yield and CCE%. The Ni catalyst was found to be the most effective catalyst in terms of the maximum H2 yield (8.22 mmol g−1 biomass with purity of 56.12 vol%), highest total gas yield of 80.21 wt%, and CCE of 49.06% owing to its relatively high catalytic activity for promoting water-gas shift, as well as tar and char reforming reactions. The average LHV of syngas was obtained to be 9 MJ N m−3. Furthermore, the considerable decrease in tar and char contents from 20.12 wt% and 21.77 wt% (without catalyst at 700 °C) to 9.32 wt% and 10.47 wt% (with Ni catalyst) was recorded.

OBJECTIVE To determine the clinical and biochemical pattern of parathyroid disorders in a tertiary care setting.. METHODS The cross-sectional study was conducted at the Armed Forces Institute of Pathology, Rawalpindi, Pakistan, from September 2017 to February 2018, and comprised patients with suspected parathyroid disorders. A panel of biochemical tests were used for diagnosis of parathyroid disorders, which included parathyroid hormone levels, total calcium, ionized calcium, inorganic phosphorus, alkaline phosphatase, magnesium, total vitamin D and urinary calcium-to-creatinine ratio. SPSS 24 was used for data analysis. RESULTS Of the 384 subjects, 248(65%) were male and 136(35%) were female. Overall mean age was 48±19years. Of the total, 302(786%) had parathyroid issues, with 244(81%) having secondary hyperparathyroidism. Mean serum total calcium, phosphorus, ionized calcium, magnesium and total vitamin D were 8.98±1.52 mg/dl, 4.0±1.30 mg/dl, 4.65±0.52 mg/dl, 2.11±0.27 mg/dl and 20.5±8.52 ngml respectively. Of the patients diagnosed with secondary hyperparathyroidism, 72.2% patients had chronic kidney disease and 20.2% had isolated vitamin D deficiency. CONCLUSIONS Parathyroid disorders had significant impact on bone health. Moreover, secondary hyperparathyroidism was seen to be emerging as a major endocrine problem, especially in chronic kidney disease patients and vitamin D-deficient individuals.

Pseudohypoparathyroidism (PHP) is an extremely rare group of disorders. It is a spectrum of disorders caused by end organ resistance to parathyroid hormone (PTH) and is represented by impaired signalling that activates cAMP dependent pathways via alpha subunit of G-protein (GS). It is characterised by hypocalcemia, hyperphosphatemia, raised PTH levels due to insensitivity to biological activity of PTH, and normal renal function tests. We describe a case of 10-year girl who presented with fear of falling down from heights. Her laboratory evaluation and skeletal survey showed evidence of PHP along with features of Albright's hereditary osteodystrophy (AHO) pointing towards the diagnosis of PHP type 1a.

Seven quality control (7QC) tools are used for reducing defects during manufacturing. These tools are highly effective in productivity and quality improvement. In this case, the study of the 7QC tools was applied in an automotive factory in order to reduce paint shop defects. Within four months the production line was inspected, defects were categorized and the 7QC tools were successfully applied, reducing the overall defect rate by 70%. Although every tool was important, the cause and effect diagram was responsible for finding the root causes of the defects.

This paper primarily focuses on an advance control strategy to enhance the low voltage ride through (LVRT) capability in doubly fed induction generator (DFIG) based wind energy conversion system (WCES). In the proposed control strategy, the captured wind energy during grid faults circumstances is stored timidly in the rotor&rsquo, s inertia kinetic energy. Though a minimal amount of energy is available in the grid, stator current and DC-link voltage are set beneath the perilous levels. However, both the required stator voltage and stator current are kept within a tolerable range of rotor side converter (RSC), through state feedback linearization technique for maintaining the accurate control to suppress the overvoltage and overcurrent. Furthermore, stator current oscillations are significantly suppressed during fault transient. The input mechanical energy from the wind turbine can be resumed after the fault clearance. In spite of being dissipated in the resistors of crowbar circuit, as in the conventional LVRT assemblies, torque balancing among electrical and mechanical measures is attained, DC-link voltage instabilities and rotor speed inconsistencies are substantially reduced. As a result, a noticeable reduction in the requirement of reactive power and swift restoration of terminal voltage on fault clearance is acquired successfully. Correspondingly, several tests are conducted to validate the effectiveness and enhancement in the performance of the DFIG based wind farms, when the proposed control strategy is implemented over it during numerous fault ride-through circumstances.

Pakistan is facing a severe energy crisis of its time with significant generation deficit in recent years. The future plan shows hydro and thermal coal generation as major contributor and Wind power to replace Thermal-oil generation in long run. This paper proposes a Super grid model for the transfer of bulk power from generation station to the load centres, which can provide efficient transmission between generation and load centres and is also adaptive to deal with variations in power from renewable generations. A dynamic simulation analysis is performed on six-terminal MTDC (Multi-Terminal High Voltage Direct Current) system VSC (Voltage Source Converter) based MTDC meshed grid with different control operations. The results show that the proposed super grid model can provide efficient transmission between generation and load centres and it is also adaptive to deal with variation in power from renewable generation.

Identifying and tackling indispensable developments in microalgae-based bio-economy should be a priority to unravel the contentious water-food-energy-environment nexus that algae inhabit. This research investigated the catalytic and non-catalytic steam gasification of two types of lipid-extracted microalgae biomasses, Chlorella vulgaris and Spirulina platensis in a thermogravimetric analyzer coupled with online mass spectrometry. A hybrid-functional mixture consisting of CaO naturally derived from waste eggshell as catalyst and sorbent, Ni as catalyst and Y2O3 as support was employed during the gasification that mainly generated H2, CO and CO2. The varied CaO loading (10 to 50 wt%) showed an evident effect on the overall gasification of lipid-extracted microalgae biomass, indicating an optimal CaO loading of 40 wt% for Ni-CaO-Y2O3 mixed materials which enabled 400.81 and 324.93 mL g−1 of H2 yield, with maximum purity of up to 53.25 and 41.82 vol% in gaseous product for Chlorella vulgaris and Spirulina microalgae residues, respectively. The addition of Ni, Y2O3 in mixed form (Ni-CaO, Ni-CaO-Y2O3, CaO-Y2O3 and Ni-Y2O3) drastically enhanced H2 yield and its purity. Ni-CaO produced the maximum H2 yield and purity of 497.29 and 435 mL g−1, and 63.15 and 45.78 vol% for Chlorella vulgaris and Spirulina platensis, respectively.

Conventional cellular networks are gradually becoming heterogeneous due to deployment of femtocells within cellular networks. Femtocells have been considered by the wireless industry as a promising solution not only to improve indoor coverage and capacity but also to unload traffic from already overburdened macro base stations. Therefore, effective mitigation of both cross-tier and co-tier interference is a major design challenge hetereogenuous cellular networks. In this work stochastic geometry based model is developed for two-tier (macro-femto) heterogeneous cellular networks by using Matern hardcore point process leveraging results on Voronoi tessellations. Complex system level simulations are used to evaluate SIR performance, coverage and capacity of networks. This paper considers fractional frequency reuse to mitigate co-tier and cross-tier interferences. Simulation results confirm significant improvement in coverage, and capacity of the networks using proposed model.

There is a variety of converter topologies applicable for switched reluctance machine. The simplicity, reliability, and suitability are key factors to consider for converter selection for the motor. The selection of switching schemes is also of worth importance for either converter selection. This paper presents the calculation method of switching losses in asymmetrical H-bridge converter for the motor. The data of energy loss is experimentally obtained and then included in the simulation model of the machine to predict the converter losses. The experimental based input data suits the trend of energy loss for a range of current.