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Articles by Shahid Iqbal
Total Records ( 5 ) for Shahid Iqbal
  Shahid Iqbal and Rosli Besar
  A bipolar Cockcroft-Walton Voltage Multiplier (CWVM) is proposed as an attractive alternative to the symmetrical Cockcroft-Walton voltage multiplier for continuous wave gas lasers (e.g. carbon dioxide gas laser). The proposed CWVM formed by combining positive and negative voltage multipliers consisting of equal number of stages and driving in parallel by an ac voltage source. The proposed voltage multiplier needs only one ac power source, therefore there was no need of center taped high voltage transformer, unlike symmetrical voltage multiplier which require center-tape transformer. It possess inherit ability of cancellation of fundamental and higher order odd harmonics of ripple components, unlike the symmetrical CWVM which may generate odd harmonic of ripple in case of any asymmetry of driving voltage. In addition to this the proposed voltage multiplier has faster transient rise and less voltage drop as compared symmetrical CWVM. The experimental and simulation results are presented to show the effectiveness of proposed voltage multiplier.
  Shahid Iqbal , Ghanshyam Kumar Singh and Rosli Besar
  An accurate model of 555IC astable multivibrator circuit has been presented in this paper. The closure resistance of the discharge transistor, which was ignored in the previous analysis, has been taken into consideration in this model. The equations developed in the model are plotted in Matlab. The plot of these equations shows that when RA < < RB the discharging time becomes much larger than the charging time and the duty cycle of the output waveform becomes much smaller than 50%. These results has been found in complete agreement with experimental results for all values of RA and RB.
  Shahid Iqbal , Muhammad Ibrahim Chaudhary and Muhammad Akber Anjum
  The performance of Kinnow mandarin (Citrus reticulata Blanco) on six citrus rootstocks i.e. Citrumelo 4475, Citrumelo 1452, Volkamariana, Yuma citrange, Mithi and Rough lemon was studied during its sixth and seventh year of transplanting. Plant height was not affected by the rootstocks used. Maximum canopy spread and stem girth were recorded on Mithi while minimum canopy spread and stem girth were on Yuma citrange and Citrumelo 1452 respectively. Fruit set was not influenced significantly by the rootstocks used. Although fruit drops in grafted plants ranged from 35.75-93.33 percent from button to pre-harvest drop, the rootstock means in each drop were non-significant. The highest mean number of fruits/plant was 285 fruits on Citrumelo 4475 and the lowest 77.5 fruits on Yuma citrange rootstock.
  Shahid Iqbal , Tariq Mahmood , Tahira , Muhammad Ali , Muhammad Anwar and Muhammad Sarwar
  Interrelationships between yield and its components were determined by genotypic correlation and path coefficient analysis in ten soybean varieties. The results indicated that seed yield plant–1 was positively and significantly associated with all parameters studied. The results also showed that pods plant–1 has maximum positive direct effect on yield plant–1. It was followed by 100 seed weight and seeds pod–1. Plant height had negative direct effect on yield plant–1. It was concluded that pods plant–1, seeds pod-` and 100 seed weight were the main yield components.
  Raja Adil SARFRAZ , Tasneem Gul KAZI , Shahid IQBAL , Hassan Imran AFRIDI , Mohammad K. JAMALI , Nusrat JALBANI and Mohammad Bilal ARAIN
  The amino acids complexes of osmium(II), i.e. [Os(h 6-p-cymene)(h1-N-(rac)-phenylglycine methyl ester)Cl2] (A) and [Os(h 6-p-cymene) (h1-N,N`-(S)-phenylalanine amido) Cl] (B), were prepared by an ultrasound energy-assisted method at room temperature. The solid structures of the newly synthesized complexes were determined by single crystal X-ray analysis. In A, osmium is bonded to 2 chloride ligands, the h 6-coordinated p-cymene molecule, and to a nitrogen atom of the corresponding amino acid derived ligand, whereas in the case of B the central osmium is surrounded by an N, N’ bidentate amino amide ligand, by an h 6-coordinated p-cymene molecule, and a chloride ligand. Both complexes have a pseudo-tetrahedral geometry. As shown by X-ray structure, A exhibited racemization of the corresponding ligand. The ligand retained its configuration in B with co-crystallization of the 2 diastereomers, ROsSC and SOsSC, in a single crystal.
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