Wyniki wyszukiwania - Biblioteka Nauki

1

Influence of flight control law on spin dynamics of aerodynamically asymmetric aircraft

100%

Malik B. , Akhtar S. , Masood J.

Journal of Theoretical and Applied Mechanics

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2017

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tom Vol. 55 nr 3

963—975

EN

In this paper, we analyze the spin dynamics of an aerodynamically asymmetric aircraft in open-loop configuration and also evaluate the performance of gain scheduled flight control law in improving dynamic characteristics of aircraft spin. A look-up tables based aerodynamic model is developed from static, coning and oscillatory coning rotary balance wind tunnel test data. As a starting point, all possible steady spin modes are identified by solving the aircraft dynamic model comprising moment equations. The influence of high-alpha yawing moment asymmetry on predicted right and left spin modes is discussed. Six degree of freedom simulations of left and right flat spins are performed in open-loop and closed-loop configurations with the flight control law. Our studies reveal that large amplitude oscillations in the angle of attack and sideslip observed in the open-loop configuration are significantly damped by the control law. The control law reduces the recovery time of the left flat spin. However, the aircraft natural tendency to rotate rightwards due to yawing moment asymmetry at high angles of attack renders flight control law ineffective in aiding the recovery of the right flat spin.

2

Connectivity based technique for localization of nodes in wireless sensor networks

100%

Farooq-I-Azam M. , Ayyaz M. N. , Akhtar S.

Przegląd Elektrotechniczny

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2013

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tom R. 89, nr 5

171-175

EN

We propose a localization algorithm for wireless sensor networks, which is simple in design, does not involve significant overhead and yet provides acceptable position estimates of sensor nodes. The algorithm uses settled nodes as beacon nodes so as to increase the number of beacon nodes. The algorithm is range free and does not need any additional piece of hardware for ranging. It also does not involve any significant communication overhead for localization. The simulation and results show that good localization accuracy is achieved for outdoor environments.

PL

W artykule opisano algorytm lokalizacji dla sieci czujników bezprzewodowych, cechujący się niskimi kosztami ogólnymi implementacji i odpowiednią dokładność estymacji pozycji. W metodzie wykorzystane są węzły osadzone jako węzły sieci. Algorytm nie ma ograniczeń zasięgowych i nie wymaga dodatkowego sprzętu do szacowania odległości. Wyniki badań symulacyjnych potwierdziły dobrą dokładność lokalizacji w środowisku zewnętrznym.

3

Comparative analysis of buckling load of circular and corrugated tubes by utilizing key performance indicators

100%

Rahim M. R. , Akhtar S. , Bharti P. K.

International Journal of Applied Mechanics and Engineering

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2017

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tom Vol. 22, no. 3

789--797

EN

The performance of buckling load of tubular structures under quasi-static axial loading is quite appreciable, numerous tubes of various cross-section have been extensively investigated and corrugated sections have been designed to further improve the performance. In this paper, a carefully designed set of key performance indicators (KPIs) is utilized to assess and compare the buckling load of circular and corrugated tubes. A series of diagrams related to KPIs with various parameters of tubes are presented to demonstrate the influence of sectional configuration on the performance of tubes as well as the effect of the material on the potential of the same. The work is inestimable to engineering designs and applications, and further studies on the buckling load of other configurations.

4

Delayed diagnosis of ‘Bancroftian filarial pleural effusion’

100%

Akhtar S. , Gumashta R. , Gumashta J.

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nr 2

207-210

EN

The authors report an unusual case of 60 year old male, who got admitted in a tertiary health care institute in Maharashtra (India) for chest pain and breathlessness and was provisionally diagnosed as ‘pleural effusion with suspicion of malignancy’. However, the pleural fluid cytology, conducted later, assisted in diagnosing this case as ‘Pleural Effusion due to Bancroftian Filariasis’. The patient responded well with oral medication of diethyl carbamazine within a couple of days. The patient could not be followed up as he left the hospital against medical advice

5

Cytodiagnosis of filarial infection on a non healing ulcer: an unusual presentation and review of literature

88%

Akhtar S. , Gumashta R. , Pande S. , Maimoon S. , Mahore S.

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nr 2

195-199

EN

The authors report an unusual case of a 33-year-old Indian male adult, who sought treatment for skin infection, skin ulcer and oedema of leg for two years, but got no relief until he was incidentally diagnosed by scrape cytology for presence of microfilaria in leg ulcer, blood and pleural fluid. The patient was fully cured after receiving complete treatment for filariasis

6

Morphological and molecular identification of Paramphistomum epiclitum from buffaloes in Pakistan

75%

Khan I. , Afshan K. , Shah S. , Akhtar S. , Komal M. , Firasat S.

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2020

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tom 65

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nr 1

7

Removal of Cr(III) through bread mold fungus

75%

Shoaib A. , Aslam N. , Athar M. M. , Akhtar S. , Nafisa , Khurshid S.

Polish Journal of Environmental Studies

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2013

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tom 22

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nr 4

EN

Cr(III) removal ability of indigenous soil fungus of Pakistan (i.e. Rhizopus arrhizus Fisher) was checked through batch trails. Experiments were performed by taking 0.1 g of powdered fungal biomass in 100 mL of metal solution kept at 150 rpm for 3 hours. Results of FTIR spectroscopy revealed that amine (-NH2) and hydroxyl (-OH) groups participated in Cr(III) binding with the fungal biomass. There was an inversely proportional relationship between adsorption efficiency and capacity on increasing initial metal concentration in the range of 20-100 mg/L. The adsorption capacity of fungal biomass was 43.47 mg/g as determined by Langmuir isotherm. High correlation coefficient (R2: 0.99) acquired through Langumir and Frendulich models adequately described the adsorption mechanism on fungal biomass. pH optimization trials in the range of 2-10 exhibited significantly greater adsorption efficiency of 75% at pH 4, while metal removal rate declined with increasing pH. Adsorption/adsorption trials with four acids indicted that maximum desorption of Cr(III) was found with HCl, followed by HNO3, CH3COOH, and H2SO4. Adsorption-based trials summarized that R. arrhizus is a potential and inexpensive biomaterial with viable application in the removal of Cr(III) from the aqueous solution.

8

Invasion impact analysis of Broussonetia papyrifera in Pakistan

63%

Qureshi H. , Anwar T. , Fatima S. , Akhtar S. , Khan S. , Wassem M. , Mohibullah M. , Shirani M. , Riaz S. , Azeem M.

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nr 4

9

Seasonal variation of aflatoxin B1 content in dairy feed

63%

Ismail A. , Riaz M. , Akhtar S. , Yoo S. H. , Park S. , Abid M. , Aziz M. , Ahmad Z.

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2017

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tom 26

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nr 1

EN

Aflatoxin B1 (AFB1 ) is a fungal metabolite and highly carcinogenic compound of category 1 according to the International Agency for Research on Cancer. In the liver AFB1 from contaminated feed is bioconverted into aflatoxin M1 and can be easily diffused to the animal milk. Provision of healthy milk for humans, particularly infants and adults, therefore, entails monitoring of AFB1 level in the feed for dairy animals. In the present study, AFB1 level was monitored in three different types of animal feed comprising commercially available animal feed, fresh fodder and leftover bread fed to dairy animals between October 2014 and September 2015. AFB1 was found in all collected feed samples at the amounts: 30.5%, 2.8% and 88.9% in commercial feed, fresh fodder and leftover bread samples, respectively. All these levels were over the EU permissible limits (5 μg · kg−1). Mean maximum levels of AFB1 were observed in all samples collected in the winter season, whereas the mean minimum levels – in the summer months. The results of the present study indicated that the leftover bread samples and commercial feed contain high levels of AFB1 , and so strict measures should be adopted to prevent dairy animal feed and at the same time the animal milk from aflatoxin contamination.