Wyniki wyszukiwania - BazTech

1

Type 2 and type 3 fuzzy-backstepping controller for active suspension system with nonlinearity compensate

Hussein N.A., Al-Zughaibi A.I.H., Ali M., Salman R.J.

Archives of Materials Science and Engineering

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2025

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Vol. 131, nr 2

69--85

EN

Purpose: The paper aims to introduce the development of a new hybrid control system technique design based on type 3 and type 2 fuzzy inference systems enforcing the Backstepping control method to improve the active suspension system. Design/methodology/approach: In the work, higher-order fuzzy backstepping tracking control for the nonlinear active suspension system of the vehicles is imposed to compensate for the effect of dead zone and hysteresis in the actuator. Thus, it integrates the mathematical strength of Backstepping with the flexibility of Fuzzy Logic, ensuring minimised oscillations and a seamless dynamic reaction to unexpected variations. The technology maximises passenger comfort and vehicle stability for reliable driving. A quarter car with 2DOF was employed to examine the suggested control. Findings: Using MATLAB/Environment, a comparison between the performance of the type 3 and type 2 fuzzy backstepping control systems with a passive system was simulated. using the type 3,2 fuzzy backstepping control in case of the dead zone and hysteresis action compensates for the active system compared to the passive system in terms of displacement, velocity, acceleration and control force. it was found that the suggested hybrid control improves the system performance in terms of a comfortable and safe ride by reducing the rms acceleration of the sprung mass to 0.0126 m\s2 in case of dead zone compensation and to 0.132 m\s2 in case of hysteresis compensate. Research limitations/implications: It is suggested that carrying out the hybrid control improves the system performance at greater stables and controls the quenching process to achieve a more comfortable and safe ride. Originality/value: As a result, the proposed type 3 and type 2 fuzzy backstepping controller designed for nonlinear active suspension is robust and realisable; hence, it has the potential to compensate for the effect of dead zone and hysteresis and minimise the vertical acceleration to get ride comfort.

2

Study of tensile, hardness, and compressive properties of prosthetic pylon made of ramie and carbon/glass hybrid composite materials

Ali M., Hashim H.A., Oleiw A.H., Mohmmed J.H.

Archives of Materials Science and Engineering

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2025

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Vol. 132, nr 1

21--28

EN

Purpose: Prosthetic pylons are the columns that connect the prosthesis to the person’s body and play a vital role in providing stability, comfort, and functional performance to prosthetic users. Improving the properties of the columns contributes significantly to enhancing the user experience. The research aims to develop prosthetic pylons’ mechanical properties using natural and synthetic fibres. Design/methodology/approach: We could achieve these objectives by performing the composite prosthetic pylon materials used to replace conventional prosthetic pylon materials made of titanium, aluminium, or stainless steel. Findings: The results demonstrated that the type and quantity of reinforcement layers had a substantial effect on the mechanical properties of laminated composites. The results showed that the samples made of two layers of synthetic hybrid (glass and carbon) fibers gave better properties in terms of tensile strength, Young’s modulus, hardness, and compressive strength were 123 MPa, 6.5 GPa, 86 shore D, and 80 MPa, respectively compared to the samples made of three layers of ramie natural fiber. At the same time, the percentage of elongation was higher for ramie reinforced composite samples. Research limitations/implications: The vacuum method was used to produce specimens with polyester as the matrix, and varying numbers of synthetic hybrid (carbon and glass) and natural (ramie) fibre layers as reinforcing materials. The mechanical characteristics (tensile strength, elongation percentage at break, Young’s modulus, compressive strength, and hardness) of each type of composite material were tested and evaluated. Originality/value: The effect of both materials gave acceptable results and proved their suitability for use instead of some metal materials that cause fatigue, exhaustion, and discomfort to users.

3

Effect of study of composite materials under high-velocity impact

Hasan I.S., Ali M., Hussein E.Q.

Archives of Materials Science and Engineering

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2025

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Vol. 132, nr 2

49--58

EN

Purpose: The research investigates the design, fabrication, and experimental and theoretical testing of a hybrid composite material. The purpose of the research is to find the design and precise calibration of a custom-made projectile launcher, which ensures consistency in the impact tests. Design/methodology/approach: It can achieve these aims by calibration according to air pressure variation, checking the consistency in the velocity of the projectile, hence proving the reliability of the device for impact resistance measurements. Findings: Test results indicated that an increase in glass fibre percentage significantly improved the values of tensile strength and shock resistance for the tested samples, with the best performance attained for specimens containing a 60% fibre content. The addition of aluminium powder exhibited a moderate improvement in the material characteristics at impact absorption. This study proposed that the addition of carbon fibres or replacing aluminium powder with copper powder could further increase the resistance to impact. Research limitations/implications: It is suggested to carry out the study, which provides useful input into the development and optimisation of the hybrid composite materials, plus forms an extremely solid basis for studies that could be dedicated later to further improvement of the material performance in view of commercial applications. By combining practical testing with theoretical research using SolidWorks and ANSYS, it has been proven that hybrid materials work well in any application requiring high tensile strength and impact resistance. Originality/value: The effect of aluminium powder exhibited a moderate improvement of the material characteristics at impact absorption. It has again been proposed that the addition of carbon fibres or replacing aluminium powder with copper powder will further increase the resistance to impact. The results showed a significant increase in tensile strength and shock resistance, especially for samples affected by the glass fibre content, which improved the shock resistance grade of the material.

4

An experimental investigation of oil jet lubrication effects at various injection angles, cutting parameters, and pressure on surface roughness in different-speed machinery

Abdulsahib R.A., Ali M., Majeed M.H.

Archives of Materials Science and Engineering

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2025

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Vol. 133, nr 1

34--41

EN

Purpose: This study investigates oil jet lubrication’s effects in different-speed machining, testing injection angles (15° and 40°) and pressures (6–12 bar) on surface roughness and wear. Design/methodology/approach: We can achieve these goals by performing the oil jet lubrication used throughout the turning process, with two different injection angles (15° and 40°) included in the lubrication conditions. Findings: Results show optimal performance at 15° and 6 bar, reducing roughness and temperature. The findings aid in selecting lubrication parameters for improved machining efficiency. One of the more significant findings from this study is that at 40° and 6 bar of pressure, the cutting speed ranges from 48 to 264 meters per minute, with the highest temperature reaching 134%. In contrast, under 15° and 6 bar, the highest temperature is 118%. Research limitations/implications: We suggest that you carry out a quality surface, it is necessary to experiment with the cutting speed that significantly impacts the tools’ and workpiece’s wear and surface roughness. As the workpiece undergoes more plastic deformation at a higher cutting speed, a greater amount of mechanical energy is converted into heat energy, resulting in a notable increase in temperature. Low-carbon steel and various cutting tools were used in the studies. Originality/value: The effect of variables studied was cutting speeds (48, 88, 180, 264) m/min, feed rates (0.03, 0.043, 0.075) mm/rev, depths of cut (1) mm, and injection angles (15° and 40°). Lubrication pressures ranged from 6 bar to 12 bar. No one has certainly facilitated improvements in the tribological properties of (AL-Rashid Oil) SAE 15W_40 through Oil jet lubrication, which was used throughout the turning process, with two different injection angles (15° and 40°) included in the lubrication conditions.

5

Effect of nano-additives on friction and wear characteristics of blended lubricants containing "palm oil and Al-Rashid engine oil SAE 15W_40"

Aliwi S. Y., Ali M., Majeed M. H.

Journal of Achievements in Materials and Manufacturing Engineering

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2024

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Vol. 125, nr 1

5--15

EN

Purpose: The research aims to evaluate the nano-additives for oil, decreasing friction, surface roughness, and decreasing wear. Design/methodology/approach: Wear and friction coefficient are examined using a pin on a disk device; adding 2 wt.% nano-additives to the blended lubricant resulted in maximum friction and wear. Findings: In the current research, one of the more significant findings to emerge from this study is that the nano-additives increase viscosity and reduce wear and friction coefficient. The highest viscosity values were when adding GNP, and improving the percentage of nano-additives leads to an increase in viscosity. Research limitations/implications: The results reveal that the additive was chosen as the most appropriate concentration in the blended lubricant. Practical implications: An experimental investigation was conducted to explore the effects of nano-additive graphene nano-powder (GNPs), molybdenum disulfide (MoS2), and titanium oxides (Tio2) in concentrations (0.5%,1%, 1.5%, 2%,2.5% ) as additives to engine oil (Al-Rashid oil) SAE 15W_40 and 5% palm oil. Originality/value: The results presented in the given paper may facilitate improvements in the nano-additives, resulting in increased viscosity compared to the base oil.

6

Effect of carburising treatment parameters on low carbon steel properties for vehicle structures

Al-Asadi N.K.F., Ali M., Hassan A.K.

Archives of Materials Science and Engineering

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2024

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Vol. 129, nr 1

17--23

EN

Purpose: The purpose of conducting this research is to improve the mechanical properties of low-carbon steel for use in various industrial applications at a lower cost than titanium and high-entropy alloys. Design/methodology/approach: We can achieve the goals by performing carburising processes at different depths that depend on the heat treatment conditions. Findings: The results showed a significant improvement in tensile strength (23, 126, 146 MPa), surface hardness (134, 516, 246 MPa), and a decrease in elongation (60, 91, 88%); in slow cooling in the furnace, water quenching, water quenching with annealing in succession where the mechanical properties are controlled by controlling the refining and heat treatment conditions to control the microstructure and desired properties that achieve the best steel surface. The importance of improvements in tensile strength, hardness, and elongation for industrial applications is the ability to withstand work in complex industrial conditions based on the amount of applied forces and high temperatures. Research limitations/implications: We suggest carrying out the carburising processes at greater depth and controlling the quenching process to achieve better mechanical properties. Originality/value: The effect of carburizing at different depths on low-carbon stainless steel was studied at different annealing conditions by controlling the cooling rate. The results showed a significant increase in tensile strength, especially for samples that were carbonised and quenched in water, as the best results in tensile strength, hardness, and elongation were for samples quenched in water.

7

Numerical analysis of the thermal behaviour and performance of a brake system with temperature-dependent material properties

Hassan M. A., Ali M., Abdullah O. I.

Archives of Materials Science and Engineering

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2023

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Vol. 122, nr 2

58--69

EN

Purpose: The brake system is the most significant component of a vehicle because it protects the driver, passengers, other road users, and property on both sides of the road. The basic principle of the disc brake system depends on the friction-based between the brake pads and rotor disc. Design/methodology/approach: The paper introduced a developed 3D finite element thermal model of the brake system to simulate the heat generated by friction in the vehicle's disc brake. Findings: The results presented the surface temperature at any instant of the disc brake under various initial velocities when the materials properties of the rotor disc and pad depend on temperature. Research limitations/implications: The main aim of the present paper is to build a numerical model to simulate the braking process under various initial vehicle velocities and investigate the influence of the material properties when they function on temperature and constant. Originality/value: The maximum difference between the two cases (contact and depend on the temperature) was 17 K for the initial velocity of 144,120. Also, it was found out that the percentage differences of the surface temperature increasing with the rise in initial vehicle velocity were 323% and 392.5% when the initial velocity of the vehicle increased from 100 km/h to 144 km/h.

8

Experimental study of the mechanical and corrosion properties of ethyl silicate resin applied on low carbon steel

Ali M., Mohmmed J.H., Zainulabdeen A.A.

Archives of Materials Science and Engineering

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2021

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Vol. 108, nr 2

68--74

EN

Purpose: This work aimed at evaluating the properties of the ethyl silicate-based coating that can be applied on low carbon steel. Design/methodology/approach: Two mixture ratio types (2:1, and 3:2) of resin and hardener respectively were used to prepared two specimen models (A and B). Findings: It found that some mechanical properties (tensile, hardness, and impact strength) of ethyl silicate resin were evaluated according to standard criteria. Research limitations/implications: The effect of heat treatments at various temperatures (100, 150, and 200°C) and holding at different times (10, 20 & 30) min on hardness was investigated. Practical implications: Moreover, an open circuit potential corrosion test with a solution of 3.5% Sodium Chloride at room temperature and 60°C was used to determine the corrosion resistance of low carbon steel specimens coated with the two mixture types. Originality/value: The effects of mixture ratios (for resin and hardener) and heat treatment conditions on properties of ethyl silicate-based coating were studied. From obtained results, acceptable values of tensile, hardness, and toughness were recorded. Increasing heat treatment temperature and holding time leads to enhance hardness for both model types. An open circuit potential (OCP) tests show that there is an enhancement of protective properties of ethyl silicate coatings with mixture type B in comparison with type A was achieved. Generally, the results indicate that specimen model B has higher properties as compared with specimen model A.

9

Buckling and bending properties of aluminium plate with multiple cracks

Mohmmed J. H., Mahmood N. Y., Ali M., Zainulabdeen A. A.

Archives of Materials Science and Engineering

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2020

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Vol. 106, nr 2

49--58

EN

Purpose: In this paper, the bending strength and buckling stability of (AA 7075-T6) aluminium plate weakened by many transverse cracks, which located at different positions, subjected to concentrated loads applied at the ends were analysed. Design/methodology/approach: Numerical modelling and calculation by the finite element method (ANSYS Package), for the critical load of bending and compression panel were estimated. Findings: It found that the variation of the critical stress in bending and buckling is proportional to the crack conditions (no. of crack and location). In general, the critical load in bending and buckling decreases with increasing the crack number in structure. Research limitations/implications: For both bending and buckling, two transverse cracks on one face of plate is more stable than two transverse cracks on opposite faces. Practical implications: In addition, many experimental tests were carried out by using an INSTRON test machine to obtain the buckling critical loads, where the experimental results were compared with the ones of the finite element method. Furthermore, bending strength was calculated theoretically for the cracked panel. Originality/value: Comparison between the experimental and numerical (FE based model) data and between the theoretical and nu-merical (FE based model) data for buckling and bending strength respectively indicate the precise and the simplicity of the developed models to determine the critical loads in such cases.

10

Boundary layer analysis in nanofluid flow past a permeable moving wedge in presence of magnetic field by using Falkner – skan model

Ali M., Alim M. A.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 4

1005--1013

EN

In the present work, the effect of various dimensionless parameters on the momentum, thermal and concentration boundary layer are analyzed. In this respect we have considered the MHD boundary layer flow of heat and transfer over a porous wedge surface in a nanofluid. The governing partial differential equations are converted into ordinary differential equations by using the similarity transformation. These ordinary differential equations are numerically solved using fourth order Runge–Kutta method along with shooting technique. The present results have been shown in a graphical and also in tabular form. The results indicate that the momentum boundary layer thickness reduces with increasing values of the pressure gradient parameter β for different situations and also for the magnetic parameter M but increases for the velocity ratio parameter λ and permeability parameter K*. The heat transfer rate increases for the pressure gradient parameter β, velocity ratio parameter λ, Brownian motion parameter Nb and Prandtl number Pr but opposite result is found for the increasing values of the thermoporesis parameter Nt. The nanoparticle concentration rate increases with an increase in the pressure gradient parameter β, velocity ratio parameter λ, Brownian motion parameter Nb and Lewis number Le, but decreases for the thermoporesis parameter Nt. Finally, the numerical results has compared with previously published studies and found to be in good agreement. So the validity of our results is ensured.

11

Phase evolution and microwave dielectric properties of A5M5O17-type ceramics

Ali M., Iqbal Y., Muhammad R.

Materials Science Poland

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2017

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Vol. 35, No. 2

362--367

EN

A number of A5M5O17 (A = Na, Ca, Sr, La, Nd, Sm, Gd, Dy, Yb; B = Ti, Nb, Ta) type compounds were prepared by a solid-state sintering route and characterized in terms of structure, microstructure and microwave dielectric properties. The compatibility of rare earths with mixed niobate/tantalate and titanate phases was investigated. The larger ionic radii mismatch resulted in the formation of pyrochlore and/or mixed phases while in other cases, pure A5M5O17 phase was formed. The samples exhibited relative permittivity in the range of 35 to 82, quality factor (Q × fo) = 897 GHz to 11946 GHz and temperature coefficient of resonance frequency (τf) = -120 ppm/°C to 318 ppm/°C.

12

Detailed evaluation and analysis of vision-based online traffic parameters estimation approach using low resolution web cameras

Ali M., Touko Tcheumadjeu L., Zuev S., Ruppe S.

Archives of Transport System Telematics

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2014

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Vol. 7, iss. 2

9--13

EN

In this paper, we give an overview and a detail analysis of our approach for vision-based real-time traffic parameters estimation using low-resolution web cameras. Traffic parameters estimation approach mainly includes three major steps, (1) stable background estimation, (2) vehicle detection, mean speed and traffic flow estimation, and (3) traffic scene classification into three states (normal and congested). The background image is estimated and updated in realtime by novel background estimation algorithm based on the median of First-in-First-Out (FIFO) buffer of rectified traffic images. Vehicles are detected by background subtraction followed by post-processing steps. By exploiting the domain knowledge of real-world traffic flow patterns, mean speed and traffic flow can be estimated reliably and accurately. Naive Bayes classifier with statistical features is used for traffic scene classification. The traffic parameter estimation approach is tested and evaluated at the German Aerospace Center’s (DLR) urban road research laboratory in Berlin for 24 hours of live streaming data from web-cameras with frames per second 1, 5 and 10. Image resolution is 348 x 259 and JPEG compression is 50%. Processed traffic data is cross-checked with synchronized induction loop data. Detailed evaluation and analysis shows high accuracy and robustness of traffic parameters estimation approach using low-resolution web-cameras under challenging traffic conditions.

13

Contact mechanics and wear simulations of hip resurfacing devices using computational methods

Ali M., Mao K.

Acta of Bioengineering and Biomechanics

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2014

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Vol. 16, no. 2

103--110

EN

The development of computational and numerical methods provides the option to study the contact mechanics and wear of hip resurfacing devices. The importance of these techniques is justified by the extensive amount of testing and experimental work required to verify and improve current orthopaedic implant devices. As the demands for device longevity is increasing, it is as important as ever to study techniques for providing much needed orthopaedic hip implant solutions. Through the use of advanced computer aided design and the finite element method, contact analysis of hip resurfacing devices was carried out by developing both three-dimensional and twodimensional axisymmetric models whilst considering the effects of loading conditions and material properties on the contact stresses. Following on from this, the three-dimensional model was used in combination with a unique programme to develop wear simulations and obtain cumulative wear for both the acetabular cup and femoral head simultaneously.

14

Performance Analysis of Bluetooth Zigbee and Wi-Fi Protocols in 2.4 GHz Multi-standard Zero-IF Receiver

Rahman M. A., Reaz M. B. I., Husain H., Ali M., Marufuzzaman M.

Przegląd Elektrotechniczny

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2013

|

R. 89, nr 11

225-228

EN

This paper presents a system-level modeling of a multi-standard receiver, which satisfies Bluetooth, Zigbee and Wi-Fi protocols. An analysis of different wireless receivers suited for multi-standard purposes is performed. The multi-standard Zero-IF receiver was modelled and simulated in MATLAB/SIMULINK environment. The simulation result exhibits better performance of multi-standard wireless receiver for these three protocols. The signal spectrum is verified by simulation model through the receiver for each standard and concluded that Zero-IF is the adequate topology for multi-standard receivers.

PL

Przedstawiono odbiornik pracujący w wielu standardach – ZigBee, Bluetoot i WiFi. Modelowano taki odbiornik i symulowano. Stwierdzono że odbiornik typu zero IF ma najlepsza topologię dla pracy wielostandardowej.

15

Design and Analysis of Odd-Harmonic Repetitive Control for Three-Phase Grid Connected Voltage Source Inverter

Jamil M., Latif I., Yasin A., Riaz R. A., Gulfam S. M., Ahmed A., Ali M.

Przegląd Elektrotechniczny

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2013

|

R. 89, nr 1a

292--295

EN

This paper presents a novel design and analysis of an odd-harmonic repetitive control (ORC) for a two-level three-phase grid connected voltage source inverter. An LCL filter between the inverter and the grid is used to attenuate high frequency PWM switching harmonics. The controller lowers the memory requirement, compared to a conventional repetitive controller. The control scheme contains a traditional conventional tracking controller with a dual loop feedback system, and a zero-phase noncasual filter with add-on ORC. Our analysis and simulation results suggest that the proposed control scheme is able to provide high quality output current (THD=1.8 %) even in worst case scenario.

PL

W artykule przedstawiono nową strategię sterowania ORC (ang. Odd-harmonic Repetitive Control) dla trójfazowego, dwupoziomowego sieciowego przekształtnika napięcia. Dodatkowo wykorzystano filtr wyjściowy LCL. Algorytm redukuje ilość wymaganej pamięci. Jego struktura opiera się na sterowniku nadążnym z podwójną pętlą sprzężenia zwrotnego, filtrze o zerowym przesunięciu fazy oraz ORC. Analiza i symulacje wykazały, że proponowane sterowanie może zapewnić wysokiej jakości prąd (THD=1,8%).

16

Chemical Constituents and Insecticidal Activity of Senna italica Mill. from the Sudan

Yagi S., El Tigani S., Ali M., Elkhidir I., Mohammed A. M. A.

International Letters of Chemistry, Physics and Astronomy

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2013

|

Vol. 9, iss. 2

146-151

EN

The chemical constituents and insecticidal activity of the pods of Senna italica (Caesalpiniaceae, Fabaceae) were investigated. From the chloroform extract of pods, physcion, chrysophanol, chrysophanol-10,10′-bianthrone, chrysophanol-physcion bianthrone and chrysophanol-isophyscion bianthrone, were isolated and characterized using different spectral methods. The GC-MS of the n-hexane extract revealed that the major chemical constituents of the oil were 2,6,-di-sec-butylphenol (36.69 %), di-n-octylphthalate (12.06 %), eicosane (5.46 %), tetratriacontane (4.87 %) and 2,2'-methylenebis[6-(1,1-dimethyl)-4-methylphenol (4.18 %). The n-hexane extract showed potent insecticidal activity (100 %) against Callosbruchus analis F. This study suggests that S. italica pods cannot be a source of sennosides but for other bioactive compounds.

17

Relaxation and breakup of a cylindrical liquid column

Ali M., Umemura A.

International Journal of Applied Mechanics and Engineering

|

2011

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Vol. 16, no. 1

257-270

EN

Instability of a capillary wave and breakup of a square cylindrical liquid column during its relaxation have been investigated numerically by simulating three-dimensional Navier-Stokes equations. For this investigation a computer code based on the volume-of-fluid (VOF) method has been developed and validated with published experimental results. The result shows that the agreement of numerical simulation is quite good with the experimental data. The code is then used to study the capillary wave and breakup phenomena of the liquid column. The investigation shows the underlying physics during relaxation of the square cylindrical liquid column, illustrates the formation and propagation of the capillary wave and breakup processes. The breakup behavior for the present configuration of the liquid column shows some significant differences from those predicted by conventional jet atomization theories. The formation of the capillary wave is initiated by the surface tension on the sharp edge of the square end of the cylinder and the propagation of the wave occurs due to the effect of surface tension force on the motion of the fluid. The propagation of the capillary wave to the end of the liquid column causes a disturbance in the system and makes the waves unstable which initiates the breakup of the liquid column. The characteristics of the capillary wave show that the amplitude of the swell grows faster than the neck of the wave and that of the tip wave grows much faster than other waves. The velocity of the liquid particle is dominated by the pressure in the liquid column.

18

Stability-indicating HP TLC method for determination of donepezil hydrochloride in bulk drug and pharmaceutical dosage form

Ali J., Ali M., Ahmad S., Bhavna M.

Chemia Analityczna

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2009

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Vol. 54, No. 6

1501-1516

EN

A sensitive, selective, precise and stability-indicating high-performance thin layer chroma-tographic (HPTLC) method for analysis of donepezil hydrochloride (DH) as bulk drug and in formulations was developed and validated. TLC aluminum plates pre-coated with 60 F-254 silica gel (20 x 10 cm) were used as the stationary phase. The solvent system consisted of butanol-water-glacial acetic acid (5:4:1, v/v/v). Densitometric analysis of DH was carried out in the absorbance mode at 260 nm. This system was found to give compact spots for DH (RF= 0.53 š 0.03 for six replicates). DH was subjected to acidic and alkaline hydrolysis, oxidation, dry and wet heat treatment, and photodegradation; under all these conditions the drug underwent degradation. Degradation products had significantly different RF values and thus were well separated from the pure drug. The method was validated with respect to linearity, precision, robustness, limit of detection (LOD), limit of quantification (LOQ), ruggedness and accuracy. Linearity was observed in the range 50—1000 ng per spot with a significantly high value of the correlation coefficient r2 = 0.9979; 95% confidence interval of r2 was 0.9908-0.9995. The mean S.E. value of the slope was 0.1316 with respect to the peak area. LOD and LOQ were 15.40 and 50.90 ng per spot, respectively. Statistical analysis proved that the method was repeatable and specific for the estimation of the studied drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating procedure.

PL

Opracowano i zwalidowano czułą, selektywną i precyzyjną, metody wysokosprawnej TLC do analizy chlorku donezepilu (DH) jako substancji chemicznej i w preparatach. Metoda umożliwia również ocenę trwałości leku. Zastosowano płytki na podłożu aluminiowym o wymiarach 20 * l O cm, pokryte żelem krzemionkowym 60 F-254. Jako eluent zastosowano butanol-wodę-lodowaty kwas octowy (5:4:1, v/v/v). DH wykrywano densytometrycznie przy 260 nm. W tych warunkach otrzymano zwarte plamki DH z RF= 0,53 š 0,03 dla sześciu powtórzeń. DH poddawano hydrolizie kwasowej i zasadowej, utlenianiu, ogrzewaniu na mokro i na sucho oraz naświetlaniu. We wszystkich tych przypadkach lek ulegał degradacji. Produkty degradacji miały wyraźnie różne wartości RFi były dobrze oddzielone od wyjściowego leku. Metodę walidowano uwzględniając liniowość, precyzje, odporność, wykrywalność, oznaczalność i dokładność. Liniowość obserwowano w zakresie 50—1000 ng w plamce, ze współczynnikiem korelacji r2 = 0,9979. Średnia wartość nachylenia wynosiła 0,1316 w odniesieniu do powierzchni piku. Wykrywalność i oznaczalność wynosiła odpowiednio 15,40 i 50,90 ng w plamce. Za pomocą analizy statystycznej wykazano, że metoda oznaczania badanego związku jest powtarzalna i specyficzna, umożliwia też oddzielanie leku od produktów jego degradacji, dzięki czemu może być zastosowana do badania trwałości leku.

19

Densitometric HPTLC analysis of cordifolioside A in Tinospora cordifolia and commercial formulations

Alam P., Ali M., Singh R., Shakeel F.

Acta Chromatographica

|

2009

|

Vol. 21, no. 4

683--692

EN

A densitometric HPTLC method for analysis of cordifolioside A both in 60% methanolic extract of Tinospora cordifolia and in a commercial formulation has been established and validated. Cordifolioside A was separated on aluminum-backed silica gel 60 F254 plates with chloroform-methanol 85:15 (%, v/v ) as mobile phase. A compact band was obtained for cordifolioside A at R F 0.52 ± 0.03. The limits of detection (LOD) and quantification (LOQ) were 20.12 and 60.36 ng per band, respectively. The highly precise and accurate method was used for analysis of cordifolioside A.

20

Mixing and flame holding characteristics in two-dimensional supersonic stream with perpendicular injection

Ali M., Ahmed S., Sadrul Islam A. K. M.

International Journal of Applied Mechanics and Engineering

|

2008

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Vol. 13, no. 1

5-20

EN

This paper reports the mixing of hydrogen in a supersonic airstream and the fIame holding capability of the combustion chamber. In particular, two-dimensional Navier-Stokes equations have been solved to see the effects of injector positions on mixing and fIame holding in a supersonic combustor. An explicit Harten-Yee Non-MUSCL Modified-fIux-type TVD scheme has been used to solve the system of equations, and a zeroequation algebraic turbulence model to ca1culate the eddy viscosity coefficient. The performance of combustor has been investigated by varying the distance of injector position from the left boundary keeping constant the backward-facing step height and other ca1culation parameters. The results show that the configuration for small distances of injector position has high mixing efficiency but the upstream recirculation cannot evolve properly which is an important factor for fIame holding capability. On the other hand, the configuration for very long distance has lower mixing efficiency due to lower gradient of hydrogen mass concentration on the top of the injector caused by the expansion of side jet both upstream and downstream of the injector. For moderate distances of injector position, large and elongated upstream recirculation can evolve which might be activated as a good flame holder.