Feasibility analysis of a novel hybrid-type superconducting circuit breaker in multi-terminal HVDC networks

Khan, U.A.,Lee, J.G.,Seo, I.J.,Amir, F.,Lee, B.W. North-Holland 2015 Physica. C, Superconductivity Vol.518 No.-

Voltage source converter-based HVDC systems (VSC-HVDC) are a better alternative than conventional thyristor-based HVDC systems, especially for developing multi-terminal HVDC systems (MTDC). However, one of the key obstacles in developing MTDC is the absence of an adequate protection system that can quickly detect faults, locate the faulty line and trip the HVDC circuit breakers (DCCBs) to interrupt the DC fault current. In this paper, a novel hybrid-type superconducting circuit breaker (SDCCB) is proposed and feasibility analyses of its application in MTDC are presented. The SDCCB has a superconducting fault current limiter (SFCL) located in the main current path to limit fault currents until the final trip signal is received. After the trip signal the IGBT located in the main line commutates the current into a parallel line where DC current is forced to zero by the combination of IGBTs and surge arresters. Fault simulations for three-, four- and five-terminal MTDC were performed and SDCCB performance was evaluated in these MTDC. Passive current limitation by SFCL caused a significant reduction of fault current interruption stress in the SDCCB. It was observed that the DC current could change direction in MTDC after a fault and the SDCCB was modified to break the DC current in both the forward and reverse directions. The simulation results suggest that the proposed SDCCB could successfully suppress the DC fault current, cause a timely interruption, and isolate the faulty HVDC line in MTDC.

Efficacy of a single-dose regimen of inactivated whole-cell oral cholera vaccine: results from 2 years of follow-up of a randomised trial

Qadri, Firdausi,Ali, Mohammad,Lynch, Julia,Chowdhury, Fahima,Khan, Ashraful Islam,Wierzba, Thomas F,Excler, Jean-Louis,Saha, Amit,Islam, Md Taufiqul,Begum, Yasmin A,Bhuiyan, Taufiqur R,Khanam, Farhana Elsevier 2018 LANCET INFECTIOUS DISEASES Vol.18 No.6

<P><B>Summary</B></P> <P><B>Background</B></P> <P>A single-dose regimen of inactivated whole-cell oral cholera vaccine (OCV) is attractive because it reduces logistical challenges for vaccination and could enable more people to be vaccinated. Previously, we reported the efficacy of a single dose of an OCV vaccine during the 6 months following dosing. Herein, we report the results of 2 years of follow-up.</P> <P><B>Methods</B></P> <P>In this placebo-controlled, double-blind trial done in Dhaka, Bangladesh, individuals aged 1 year or older with no history of receipt of OCV were randomly assigned to receive a single dose of inactivated OCV or oral placebo. The primary endpoint was a confirmed episode of non-bloody diarrhoea for which the onset was at least 7 days after dosing and a faecal culture was positive for <I>Vibrio cholerae</I> O1 or O139. Passive surveillance for diarrhoea was done in 13 hospitals or major clinics located in or near the study area for 2 years after the last administered dose. We assessed the protective efficacy of the OCV against culture-confirmed cholera occurring 7–730 days after dosing with both crude and multivariable per-protocol analyses. This trial is registered at ClinicalTrials.gov, number NCT02027207.</P> <P><B>Findings</B></P> <P>Between Jan 10, 2014, and Feb 4, 2014, 205 513 people were randomly assigned to receive either vaccine or placebo, of whom 204 700 (102 552 vaccine recipients and 102 148 placebo recipients) were included in the per-protocol analysis. 287 first episodes of cholera (109 among vaccine recipients and 178 among placebo recipients) were detected during the 2-year follow-up; 138 of these episodes (46 in vaccine recipients and 92 in placebo recipients) were associated with severe dehydration. The overall incidence rates of initial cholera episodes were 0·22 (95% CI 0·18 to 0·27) per 100 000 person-days in vaccine recipients versus 0·36 (0·31 to 0·42) per 100 000 person-days in placebo recipients (adjusted protective efficacy 39%, 95% CI 23 to 52). The overall incidence of severe cholera was 0·09 (0·07 to 0·12) per 100 000 person-days versus 0·19 (0·15 to 0·23; adjusted protective efficacy 50%, 29 to 65). Vaccine protective efficacy was 52% (8 to 75) against all cholera episodes and 71% (27 to 88) against severe cholera episodes in participants aged 5 years to younger than 15 years. For participants aged 15 years or older, vaccine protective efficacy was 59% (42 to 71) against all cholera episodes and 59% (35 to 74) against severe cholera. The protection in the older age groups was sustained throughout the 2-year follow-up. In participants younger than 5 years, the vaccine did not show protection against either all cholera episodes (protective efficacy −13%, −68 to 25) or severe cholera episodes (−44%, −220 to 35).</P> <P><B>Interpretation</B></P> <P>A single dose of the inactivated whole-cell OCV offered protection to older children and adults that was sustained for at least 2 years. The absence of protection of young children might reflect a lesser degree of pre-existing natural immunity in this age group.</P> <P><B>Funding</B></P> <P> <ce:grant-sponsor id='gs3' sponsor-id='http://dx.doi.org/10.13039/100000865' xlink:type='simple' xlink:role='http://www.elsevier.com/xml/linking-roles/grant-sponsor'>Bill & Melinda Gates Foundation</ce:grant-sponsor> to the International Vaccine Institute.</P>

Selection of Sahiwal Cattle Bulls on Pedigree and Progeny

Bhatti, A.A.,Khan, M.S.,Rehman, Z.,Hyder, A.U.,Hassan, F. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.1

The objective of the study was to compare ranking of Sahiwal bulls selected on the basis of highest lactation milk yield of their dams with their estimated breeding values (EBVs) using an animal model. Data on 23,761 lactation milk yield records of 5,936 cows from five main Livestock Experiment Stations in Punjab province of Pakistan (1964-2004) were used for the study. At present the young A.I bulls are required to be from A-category bull-dams. Dams were categorized as A, B, C and D if they had highest lactation milk yield of ${\geq}$2,700, 2,250-2,699, 1,800-2,249 and <1,800 litres, respectively. The EBVs for lactation milk yield were estimated for all the animals using an individual animal model having fixed effect of herd-year and season of calving and random effect of animal. Fixed effect of parity and random effect of permanent environment were incorporated when multiple lactation were used. There were 396 young bulls used for semen collection and A.I during 1973-2004. However, progeny with lactation yields recorded, were available only for 91 bulls and dams could be traced for only 63 bulls. Overall lactation milk yield averaged 1,440.8 kg. Milk yield was 10% heritable with repeatability of 39%. Ranking bulls on highest lactation milk yield of their dams, the in-vogue criteria of selecting bulls, had a rank correlation of 0.167 (p<0.190) with ranking based on EBVs from animal model analysis. Bulls' EBVs for all lactations had rank correlation of 0.716 (p<0.001) with EBVs based on first lactation milk yield and 0.766 (p<0.001) with average EBVs of dam and sire (pedigree index). Ranking of bulls on highest lactation yield of their dams has no association with their ranking based on animal model evaluation. Young Sahiwal bulls should be selected on the basis of pedigree index instead of highest lactation yield of dams. This can help improve the genetic potential of the breed accruing to conservation and development efforts.

Calorimetric studies of the crystallization process in a-Se75S25-xAgx chalcogenide glasses

Shamshad A. Khan,F.S. Al-Hazmi,A.S. Faidah,A.A. Al-Ghamdi 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Calorimetric studies of amorphous Se75S25-xAgx (x = 2, 4, 6 and 8) chalcogenide glasses are made at different heating rates (5, 10, 15 and 20 K/min) under non-isothermal condition using Differential scanning calorimetry. The values of glass transition temperature and crystallization temperature are observed to be composition and heating rate dependence. From the heating rate dependence of glass transition temperature and crystallization temperature, the activation energy for structural relaxation (△Et), the activation energy of crystallization (△Ec) and the order parameter (n) have been calculated. It is observed that Se75S19Ag6 has a minimum value of activation energy for structural relaxation (△Et), which indicates that this particular glass has a larger probability to jump to a state of lower configurational energy and higher stability in the glassy region. On the basis of the obtained experimental data the temperature difference (Tc - Tg) is found to be maximum for Se75S19Ag6, which further indicate that this glass is the thermally most stable in the entire composition range of investigation. Calorimetric studies of amorphous Se75S25-xAgx (x = 2, 4, 6 and 8) chalcogenide glasses are made at different heating rates (5, 10, 15 and 20 K/min) under non-isothermal condition using Differential scanning calorimetry. The values of glass transition temperature and crystallization temperature are observed to be composition and heating rate dependence. From the heating rate dependence of glass transition temperature and crystallization temperature, the activation energy for structural relaxation (△Et), the activation energy of crystallization (△Ec) and the order parameter (n) have been calculated. It is observed that Se75S19Ag6 has a minimum value of activation energy for structural relaxation (△Et), which indicates that this particular glass has a larger probability to jump to a state of lower configurational energy and higher stability in the glassy region. On the basis of the obtained experimental data the temperature difference (Tc - Tg) is found to be maximum for Se75S19Ag6, which further indicate that this glass is the thermally most stable in the entire composition range of investigation.

A 3D CFD analysis of flow past a hipped roof with comparison to industrial building standards

Khalid Khalil,Huzafa Khan,Divyansh Chahar,Jamie F. Townsend,Zeeshan A. Rana 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.34 No.6

Three-dimensional (3D) computational fluid dynamics (CFD) analysis of flow around a hipped-roof building representative of UK inland conditions are conducted. Unsteady simulations are performed using three variations of the k–ϵ RANS turbulence model namely, the Standard, Realizable, and RNG models, and their predictive capability is measured against current European building standards. External pressure coefficients and wind loading are found through the BS 6399-2:1997 standard (obsolete) and the current European standards (BS EN 1991-1-4:2005 and A1:20101). The current European standard provides a more conservative wind loading estimate compared to its predecessor and the k–ϵ RNG model falls within 15% of the value predicted by the current standard. Surface shear stream-traces and Q-criterion were used to analyze the flow physics for each model. The RNG model predicts immediate flow separation leading to the creation of vortical structures on the hipped-roof along with a larger separation region. It is observed that the Realizable model predicts the side vortex to be a result of both the horseshoe vortex and the flow deflected off it. These model-specific aerodynamic features present the most disparity between building standards at leeward roof locations. Finally, pedestrian comfort and safety criteria are studied where the k–ϵ Standard model predicts the most ideal pedestrian conditions and the Realizable model yields the most conservative levels.

IMPACT OF FOURWING SALTBUSH ON FEED AND WATER INTAKE AND ON BLOOD SERUM PROFILE IN SHEEP

Rasool, E.,Rafique, S.,Haq, I.U.,Khan, A.G.,Thomson, E.F. Asian Australasian Association of Animal Productio 1996 Animal Bioscience Vol.9 No.2

Sixteen Harnai males were used to evaluate the influence of varying levels of fourwing saltbush hay on feed and water intakes as well as the blood serum mineral status in a completely randomized design. The animals were grouped randomly into four, with four animals in each. The four groups were randomly allotted low, medium, high and very high levels of saltbush hay supplementation in addition to wheat straw. The animals were given fresh water at free of choice. Weekly body weight was recorded for each individual animal. Blood serum was collected for mineral contents. The experiment lasted for eight weeks. The inclusion of saltbush leaves in the diet showed a non-significant effect on the total dry matter intake. There has been a significant increase in the water intake when very high levels of saltbush were included in the ration. Lower levels showed no effect on the water intake. The animals maintained their body weight from week 1 to week 8. No treatment by weeks interactions on the potassium and sodium levels were detected. However higher levels of saltbush increased significantly the potassium and sodium contents in the serum. Calcium contents were significantly(p<0.01) lowered with the inclusion of saltbush leaves in the diet. Whereas Phosphorous contents showed an increasing(p<0.05) trend with the higher levels of saltbush. No clinical or sub-clinical toxicological symptoms were observed in the sheep with the higher mineral contents.

COMPARATIVE STUDY ON PATHOLOGY OF HEMIC SYSTEM OF THREE BROILER CHICKEN STRAINS SUFFERING FROM EXPERIMENTAL HYDROPERICARDIUM SYNDROME

Khan, S.A.,Zaidi, F.H.,Chaudhry, R.A.,Ashraf, S.K.,Mian, M.S.,Qureshi, I.R. Asian Australasian Association of Animal Productio 1995 Animal Bioscience Vol.8 No.4

The experiment was conducted to study the comparative pathology of hemic system among three different broiler chicken strains i.e. Hubbard (H), Lohmann (L) and Indian River (IR) suffering from experimentally induced Hydropericardium Syndrome (HPS). For this 50 chicks of each strain were inoculated with HPS inoculum at the age of 21 days and other 50 chicks of each broiler strain were kept as uninoculated control. After slaughtering each bird of both groups was subjected to pathological examination of heart, spleen and aorta and also for determining routine haematological parameters. The maximum values of Total Erythrocyte Count (TEC), heterophils and thrombocytes and the minimum values of Total Leukocyte Count (TLC) and Hemoglobin (Hb) content were found in H broiler strain. Percentage of monocytes, basophils and eosinophils also showed maximum decrease in H broiler chicken strain. Gross pathological lesions in the inoculated birds revealed that the heart showed ballooning due to distention of pericardial sac with pericardial fluid. Haemorrhages on the epicardium and flabbiness of the myocardium. Under the microscope, degenerative changes in myocardial tissue were seen. Lesions in the spleen included splenomegaly and haemorrhagic spots. Aorta showed flabbiness of the wall and disruption of endothelium. It is concluded that there is a marked difference in susceptibility of HPS among three different commercial broiler strains. The Hubbard broiler strain is more susceptible which is followed by the Indian River and Lohmann respectively.

Effect of Storage Time on the Rancidity and Metabolizable Energy of Rice Polishing in Poultry

Pasha, T.N.,Khattak, F.M.,Khan, D.R.,Jabbar, M.A. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.3

The storage of rice polishing (RP) with and without addition of antioxidant for sixteen weeks and its effect on rancidity and metabolizable energy values during the summer season was determined. Fifteen Single Comb White Leghorn cockerels of approximately uniform age and weight were procured and kept in metabolic cages under standard feeding and management practices. Five force feeding trials were conducted. In the first trial, fresh RP with 0 weeks of storage (diet 1 and 2) was used followed by four feeding trials with 4 (diet 3, 4), 8 (diet 5, 6), 12 (diet 7, 8), and 16 (diet 9, 10) weeks of storage of RP. The same birds were used in all trails. The birds were fasted for a period of 21 h, followed by force feeding of 20 g of RP with and without antioxidant for all storage periods. The control/fasting group was also maintained to measure endogenous fecal losses. Excreta were collected after 48 h for the determination of AME and TME values of RP. Along with the biological trials, laboratory assay of the RP stored with and without antioxidant was conducted to measure the extent of rancidity in terms of Thiobarbituric acid value (TBA). The TBA values were affected (p<0.05) by storage period and the values increased when the storage period increased from 4 to 16 weeks. However, the TBA values were significantly reduced (p<0.05) when RP was stored after addition of antioxidant when compared with the values obtained from RP stored without antioxidant (diet 3 vs. 4, 5 vs. 6, 7 vs. 8, and 9 vs. 10). The AME MJ/kg and TME MJ/kg values of RP were neither affected by increase in storage period nor addition of antioxidant. The findings of this study revealed that there was no effect of rancidity and storage time on the nutritive value, AME or TME of RP in poultry. However, TBA values were increased with the increase in storage period.

FPGA Implementation of a Neural Network for Character Recognition

Khan, F. A.,Uppal, M.,Song, W.-C.,Kang, M.-J.,Mirza, A. M. SPRINGER-VERLAG 2006 Lecture Notes in Computer Science Vol.- No.3973

Photocurrent Response of MoS₂ Field-Effect Transistor by Deep Ultraviolet Light in Atmospheric and N₂ Gas Environments

Khan, M. F.,Iqbal, M. W.,Iqbal, M. Z.,Shehzad, M. A.,Seo, Y.,Eom, Jonghwa American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.23

<P>Molybdenum disulfide (MoS<SUB>2</SUB>), which is one of the representative transition metal dichalcogenides, can be made as an atomically thin layer while preserving its semiconducting characteristics. We fabricated single-, bi-, and multilayer MoS<SUB>2</SUB> field-effect transistor (FET) by the mechanical exfoliation method and studied the effect of deep ultraviolet (DUV) light illumination. The thickness of the MoS<SUB>2</SUB> layers was determined using an optical microscope and further confirmed by Raman spectroscopy and atomic force microscopy. The MoS<SUB>2</SUB> FETs with different number of layers were assessed for DUV-sensitive performances in various environments. The photocurrent response to DUV light becomes larger with increasing numbers of MoS<SUB>2</SUB> layers and is significantly enhanced in N<SUB>2</SUB> gas environment compared with that in atmospheric environment.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-23/am506716a/production/images/medium/am-2014-06716a_0009.gif'></P>