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    Tytuł:
    Task allocation algorithms for maximizing reliability of heterogeneous distributed computing systems
    Autorzy:
    Mahmood, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/205582.pdf
    Data publikacji:
    2001
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    heurystyka
    niezawodność
    obliczenie zdecentralizowane
    przetwarzanie rozproszone
    A* algorithm
    branch-and-bound
    distributed computing
    heuristics
    reliability
    task allocation
    Opis:
    The rapid progress of microprocessor and communication technologies has made the distributed computing system economically attractive for many computer applications. One of the first problems encountered in the operation of a distributed system is the problem of allocating the tasks among the processing nodes. The task allocation problem is known to be computationally intractable for large task sets. In this paper, we consider the task allocation problem with the goal of maximizing reliability of heterogeneous distributed systems. After presenting a quantitative task allocation model, we present a least-cost branch-and-bound algorithm to find optimal task allocations. We also present two heuristic algorithms to obtain suboptimal allocations for realistic size large problems in a reasonable amount of computational time. Simulation was used to study the performance of the proposed algorithms for a large number of problems. Also, performance of the proposed algorithms has been compared with a well-known heuristics available in the literature.
    Źródło:
    Control and Cybernetics; 2001, 30, 1; 115-130
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Under Pressure DFT Investigations on Optical and Electronic Properties of PbZrO₃
    Autorzy:
    Nazir, G.
    Tariq, Saad
    Afaq, A.
    Mahmood, Q.
    Saad, S.
    Mahmood, A.
    Tariq, Samar
    Powiązania:
    https://bibliotekanauki.pl/articles/1030608.pdf
    Data publikacji:
    2018-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    density functional theory
    optical properties
    electronic structure
    high pressure
    Opis:
    In this article, density functional theory has been used to investigate the structural and optoelectronic properties of PbZrO₃ (PZO) under pressure from 0 to 350 GPa. In order to achieve ground state structural stability, generalized gradient approximations has been utilized. By studying electronic properties, indirect band-gap nature of PZO appears to change at 15 GPa to direct band-gap. Optical analysis include under pressure responses of real and imaginary parts of dielectric function, optical conductivity, optical absorption coefficient, energy loss function, refractive index, reflectivity and extinction coefficient. Most of the results have been found to be consistent with literature. Study reveals that static dielectric constant and band-gap are in accordance with the Penn model which validates our computed results. Moreover, static dielectric constant and static refractive index directly increases with pressure. Material preserves its positive value of refractive index at all pressures and therefore, it is not a negative index metamaterial. Plasma frequency increases directly with pressure that destabilize the under study material. Our results could be very useful for developing novel optoelectronic devices based on PZO suitable to work under extreme conditions.
    Źródło:
    Acta Physica Polonica A; 2018, 133, 1; 105-113
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    First principle analysis of electronic, optical and thermoelectric characteristics of XBiO3 (X = Al, Ga, In) perovskites
    Autorzy:
    Mahmood, Q.
    Rouf, S. A.
    Algrafy, E.
    Murtaza, G.
    Ramay, S. M.
    Mahmood, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818225.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    density functional theory
    structural stability
    optoelectronics
    thermoelectric applications
    indirect band gap semiconductors
    Opis:
    The perovskites XBiO3 (X = Al, Ga, In) have been studied in terms of mechanical, optical and thermoelectric behavior for energy harvesting application. Density functional theory is applied to study electronic, optical and thermoelectric properties of the studied materials. Structural, mechanical and thermodynamic stabilities are confirmed from the tolerance factor, Born mechanical stability and formation energy/specific heat capacity. Poisson and Plough ratios show the studied materials are ductile and have ability to withstand pressure. Band structure analysis shows the indirect band gap 3.0/2.1/1.0 eV for ABO/GBO/IBO. A complete set of optical spectra is reported by dielectric constants, refractive index, optical conduction, absorption of light and optical loss energy. Shifting of maximum absorption band to visible region increases the potential of perovskites XBiO3. Transport characteristics are also investigated by electrical conductivity, Seebeck coefficient and figure of merit.
    Źródło:
    Opto-Electronics Review; 2020, 28, 1; 8--14
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparative evaluation of different techniques for herniorrhaphy in calves
    Autorzy:
    Fatima, A.
    Arif Khan, M.
    Aslam, S.
    Ashraf, K.
    Khalid Mahmood, A.
    Asif, M.
    Shah, S.
    Hussain, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/16539145.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    calves
    mesh application
    suture material
    umbilical hernia
    Opis:
    Umbilical hernia is one of the most common problems in young calves. This problem occurs in dairy sector as well as in the local farmers. Present study was conducted to compare outcomes of four different techniques of herniorrhaphy. Twenty four young calves (n=24) were divided in 4 groups (A, B, C, and D) which underwent four different surgical techniques. Group A underwent vicryl plus suture material and pants-over-west technique, Group B underwent mesh application with Dexon suture material by using simple interrupted suture pattern, Group C underwent closed method with Nylon No. 3 suture material by using vertical mattress suture pattern and Group D underwent clamp application method with Silk No. 2 suture material by using simple interrupted suture pattern. The result showed that mesh application method was comparatively better with respect to feed intake, body weight gain and healing time. There was no reoccurrence with non-significant hematological changes (p≤0.05). It is concluded that mesh application method is safer than other three techniques and there are no systemic effects of this surgical intervention on calves’ health.
    Źródło:
    Polish Journal of Veterinary Sciences; 2022, 25, 2; 207-212
    1505-1773
    Pojawia się w:
    Polish Journal of Veterinary Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Review of mechanical vapour compression refrigeration system part 2: performance challenge
    Autorzy:
    Mahmood, R. A.
    Ali, O. M.
    Al-Janabi, A.
    Al-Doori, G.
    Noor, M. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2106451.pdf
    Data publikacji:
    2021
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    para
    układ chłodniczy
    współczynnik wydajności
    vapour compression
    refrigeration system
    cycle
    coefficient of performance COP
    Opis:
    Reducing energy consumption and providing high performance for a vapour compression refrigeration system are big challenges that need more attention and investigation. This paper provides an extensive review of experimental and theoretical studies to present the vapour compression refrigeration system and its modifications that can be used to improve system’s performance and reduce its energy consumption. This paper also presents the challenges that can be considered as a gab of research for the future works and investigations. Cooling capacity, refrigerant effect, energy consumption can be improved by using vapour injection technique, natural working fluid, and heat exchanger. Based on the outcome of this paper, vapour injection technique using natural refrigerant such as water can provide ultimate friendly refrigeration system. Future vision for the vapour compression refrigeration system and its new design technique using Computational Fluid Dynamic (CFD) is also considered and presented.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2021, 26, 3; 119--130
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Parameters optimization of MAG welding for enhancing the mechanical properties and buckling behaviour of welded steel
    Autorzy:
    Alwan, A. H.
    Mahmood, N. Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/368428.pdf
    Data publikacji:
    2020
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    MAG welding parameters
    critical buckling load
    Taguchi method
    ANOVA
    optimization
    spawanie MAG
    parametry spawania
    metoda Taguchi
    optymalizacja
    Opis:
    Purpose: The influence of metal active gas welding variables, including current, wire feeding speed and gas flow rate on the ultimate tensile strength and critical buckling load of steel (St.24) and the optimized welding conditions were discussed. Design/methodology/approach: The experimental steps are firstly designing the experiments, secondly conducting the mechanical tests, thirdly analysing the results through Minitab 16 and finally determining the optimum welding parameters. Confirmation tests of the optimized variables were validated. Findings: ANOVA approach manifested that the significant effect of welding variable on the tensile strength was the gas flow rate, while the current was on the critical buckling load. The results are confirmed and given the optimum values. Research limitations/implications: The influence of MAG welding variables (current, wire feeding speed and gas flow rate) on the tensile and buckling strengths of steel will be investigated in order to avoid the failure of many welded assemblies in the structures due to the buckling, in addition to reduce the requirement of long time and high cost to produce such assemblies. Therefore, it is necessary to find a solution to encounter the difficulties in their welding process. Practical implications: The major challenge was how to reduce the time and cost beside gaining the optimum properties through the designed experiments. Originality/value: The results may be helpful to design any welded joints in machine frames, structural steel connections and crane structures at the optimum condition.
    Źródło:
    Journal of Achievements in Materials and Manufacturing Engineering; 2020, 99, 1; 5-13
    1734-8412
    Pojawia się w:
    Journal of Achievements in Materials and Manufacturing Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling and Simulation of a Photovoltaic Module in Different Operating Regimes
    Autorzy:
    Jadallah, A.
    Mahmood, D.
    Abdulqader, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1402513.pdf
    Data publikacji:
    2015-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.40.+w
    77.80.-e
    Opis:
    Modern research focuses on the renewable energy sources such as solar energy. This paper presents the modeling and performance of a photovoltaic (PV) cell. A simulation code is built using MATLAB. Results show that the increase of solar radiation and of ideality factor of diode lead to an increase in the output power of PV module, while the increease of cell temperature and of the dark saturation current lead to a decrease of the power. Curves of I-V and P-V dependencies are presented for module having 50 branches connected in parallel, with each branch having 50 cells connected in series. Data for certain Iraqi governorates are taken and applied for proposed module.
    Źródło:
    Acta Physica Polonica A; 2015, 128, 2B; B-461-B-464
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effects of micronutrients (Cu, Zn, Mn, and Fe) on the growth of Spathoglottis plicata plantlets
    Autorzy:
    Yasin, Z.A.M.
    Mahmood, M.
    Shaharudiin, N.A.
    Powiązania:
    https://bibliotekanauki.pl/articles/79811.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Źródło:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2017, 98, 1
    0860-7796
    Pojawia się w:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation and Study of Some Electrical Properties of PVA-Ni(NO3)2 Composites
    Autorzy:
    Salman, S.A.
    Bakr, N. A.
    Mahmood, M.H.
    Powiązania:
    https://bibliotekanauki.pl/articles/411873.pdf
    Data publikacji:
    2015
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    polyvinyl alcohol
    Casting method
    Electrical properties
    Composites
    Opis:
    The aim of this paper is to prepare and study the (D.C.) electrical conductivity of (PVA-Ni(NO₃)₂) composites at different temperatures. For that purpose, PVA films with Ni(NO₃)₂ salt additive were prepared with different concentrations 2, 4, 6, 8 and 10 wt. % and with thickness of 45μm by using casting technique. The experimental results for PVA-Ni(NO₃)₂) films show that the (D.C.) electrical conductivity increased with increasing the filler content and the temperature, and the activation energy was decreased with increasing the filler content.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2015, 40; 36-42
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hybridization of solar/wind energy system for power generation in rural aeras
    Autorzy:
    Jadallah, A.
    Mahmood, D.
    Er, Z.
    Abdulqaedr, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1068565.pdf
    Data publikacji:
    2016-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    89.20.Bb
    89.30.Cc
    Opis:
    This work is devoted to modeling, analysis and simulation of a small-scale stand-alone wind/PV hybrid power generation system. Wind turbine is modelled and many parameters are taken into account, such as pitch angle, rotor diameter, wind speed, etc. The PV module is then modelled under nominal conditions such as cell temperature, solar radiation, etc. A MATLAB computer programs is developed to solve the mathematical model for small scale horizontal axis wind turbine and PV system. The experimental study has been conducted using a small scale wind turbine based on 500 W permanent magnet synchronous generator. A PV panel used has 36 monocrystalline silicon cells connected together in series having the ability to generate 50 W of rated power. Results show that the load consumes power from both systems but there is an excess and lack of power supply in some operating conditions, such as variation of solar radiation and wind speed.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 1; 434-437
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design of a linear quadratic regulator based on genetic model reference adaptive control
    Autorzy:
    Abdullah, Abdullah I.
    Mahmood, Ali.
    Thanoon, Mohammad A.
    Powiązania:
    https://bibliotekanauki.pl/articles/27314263.pdf
    Data publikacji:
    2022
    Wydawca:
    Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
    Tematy:
    model reference adaptive control
    gradient approach
    Linear Quadratic Regulator
    genetic algorithm
    Opis:
    The conventional control system is a controller that controls or regulates the dynamics of any other process. From time to time, a conventional control system may not behave appropriately online; this is because of many factors like a variation in the dynamics of the process itself, unexpected changes in the environment, or even undefined parameters of the system model. To overcome this problem, we have designed and implemented an adaptive controller. This paper discusses the design of a controller for a ball and beam system with Genetic Model Reference Adaptive Control (GMRAC) for an adaptive mechanism with the MIT rule. Parameter adjustment (selection) should occur using optimization methods to obtain an optimal performance, so the genetic algorithm (GA) will be used as an optimization method to obtain the optimum values for these parameters. The Linear Quadratic Regulator (LQR) controller will be used as it is one of the most popular controllers. The performance of the proposed controller with the ball and beam system will be carried out with MATLAB Simulink in order to evaluate its effectiveness. The results show satisfactory performance where the position of the ball tracks the desired model reference.
    Źródło:
    Journal of Automation Mobile Robotics and Intelligent Systems; 2022, 16, 3; 75--81
    1897-8649
    2080-2145
    Pojawia się w:
    Journal of Automation Mobile Robotics and Intelligent Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Buckling and bending properties of aluminium plate with multiple cracks
    Autorzy:
    Mohmmed, J. H.
    Mahmood, N. Y.
    Ali, M.
    Zainulabdeen, A. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818485.pdf
    Data publikacji:
    2020
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    buckling stability
    bending strength
    crack
    aluminium plate
    ANSYS package
    stabilność wyboczeniowa
    wytrzymałość na zginanie
    pęknięcie
    płyta aluminiowa
    pakiet ANSYS
    Opis:
    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.
    Źródło:
    Archives of Materials Science and Engineering; 2020, 106, 2; 49--58
    1897-2764
    Pojawia się w:
    Archives of Materials Science and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigating the effect of insoluble additives type on the drag reduction performance in a crude oil turbulent flow system
    Autorzy:
    Mahmood, Wafaa Kamil
    Abdulbari, Hayder A.
    Laft, Asaad H.
    Powiązania:
    https://bibliotekanauki.pl/articles/2142862.pdf
    Data publikacji:
    2022
    Wydawca:
    Centrum Badań i Innowacji Pro-Akademia
    Tematy:
    drag reduction
    turbulence
    insoluble additives
    crude oil
    powder
    redukcja oporu
    turbulencja
    dodatki nierozpuszczalne
    ropa naftowa
    proszek
    Opis:
    In the present work, the effect of three insoluble additives densities on reducing the drag of crude oil was investigated. The objective of the present work is to evaluate the effect of the insoluble additive’s densities on their drag reduction efficiency in hydrocarbon flow medium. Three powders with different densities are chosen, namely carbon powder, glass powder, and copper powder, with a density of 1710 kg/m3 , 2550 kg/m3 , and 8950 kg/m3 , respectively. The turbulence flow environment was created in a custom-made rotating disc apparatus with a maximum rotation speed of 300 rpm. To evaluate the effect of the powder density, the particle's size was chosen to be 100 µm. All the solutions were tested at the exact operating conditions with a rotation speed ranging between 200 to 2200 rpm. The experimental results showed a clear effect of the powder density on the drag reduction performance. The glass powders showed the highest drag reduction effect, while the copper and carbon powders were lower. The effect of the degree of turbulence on the drag reduction performance of the powders was clear, where the interaction between the powders and the turbulence structures (eddies) governed the turbulence-suppression efficiency of the additives.
    Źródło:
    Acta Innovations; 2022, 43; 44-53
    2300-5599
    Pojawia się w:
    Acta Innovations
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Seroprevalence, associated risk factors and clinico-pathological studies of buffalopox disease in various regions of Punjab province, Pakistan
    Autorzy:
    Usmani, M.W.
    Rizvi, F.
    Khatoon, A.
    Mahmood, M.S.
    Powiązania:
    https://bibliotekanauki.pl/articles/16539103.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    seropositive
    single radial hemolysis
    scab samples
    PCR
    C18L gene
    leukocytes
    Opis:
    Buffalopox (BPX) is a highly contagious disease that causes high morbidity and production losses in buffaloes. During this study, seroprevalence, effect of various associated risk factors, and pathological studies of BPX were recorded in the Punjab province. A total of 97 blood samples and 63 scabs were collected from clinically pox suspected buffaloes. Serum was harvested to perform single radial hemolysis to assess the seroprevalence, and scabs were subjected to PCR for BPX virus confirmation. Results revealed that, animal demographics and environmental associated factors showed significant effect (p<0.05,1<R2>0) on BPX occurrence. The overall BPX seroprevalence was recorded 4.18% in the Punjab province. The BPX was recorded 5.48% in Nili Ravi breed during winter (7.42%), aged 5-7 years (7.46%) under loose housing (5.51%) in the Faisalabad region (8.03%). Further, BPX was 5.37% in pregnant, 6.86% pregnant milking buffaloes during the 3rd lactation period (7.28%) in dairy herds (5.20%). The BPX was 5.22% in non-vaccinated buffaloes where multiple animals were reared together (4.99%) in the herds having 21-30 total number of animals. A total of 49 scab samples were found positive for the BPX virus via PCR with C18L gene amplification. Grossly, inflammatory lesions with pits in the center and wart-like nodules were seen on teats and udder of buffaloes. Increased leukocytes, especially neutrophils and lymphocytes, were seen in the blood of the infected animals. These results provide a broader window to understand the effect of associated risk factors, strengthen the diagnostic aid, and to contain the current spread of BPX in Pakistan to safeguard large ruminant-based livelihood.
    Źródło:
    Polish Journal of Veterinary Sciences; 2022, 25, 1; 137-147
    1505-1773
    Pojawia się w:
    Polish Journal of Veterinary Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Arsenic removal through bio sand filter using different bio-adsorbents
    Autorzy:
    Keerio, Ghulam S.
    Keerio, Hareef A.
    Ibuphoto, Khalil A.
    Laghari, Mahmood
    Panhwar, Sallahuddin
    Talpur, Mashooque A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1844385.pdf
    Data publikacji:
    2021
    Wydawca:
    Instytut Technologiczno-Przyrodniczy
    Tematy:
    arsenic
    banana peel
    bio-adsorbent
    bio-sand filter
    biochar
    rice-husk
    water treatment
    Opis:
    Arsenic is one of the most harmful pollutants in groundwater. In this paper, the Nepali bio sand filter (BSF) was modified with different bio-adsorbents, and proved to be an efficient method for arsenic removal from groundwater. Three different bio-adsorbents were used to modify the Nepali BSF. Iron nails and biochar BSF, ~96% and ~93% arsenic removal was achieved, within the range of WHO guidelines. In iron nails, BSF and biochar BSF ~15 dm3∙h–1 arsenic content water was treated. In the other two BSFs, rice-husk and banana peel were used, the arsenic removal efficiency was ~83% of both BSFs. Furthermore, the efficiency of rice-husk and banana peel BSFs can be increased by increasing the surface area of the adsorbent or by reducing the flow rate.
    Źródło:
    Journal of Water and Land Development; 2021, 48; 11-15
    1429-7426
    2083-4535
    Pojawia się w:
    Journal of Water and Land Development
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spiro-cyclotriphosphazene with three functional end groups: synthesis and structural characterization of new polycyclotriphosphazenes with Schiff-base groups
    Spiro-cyklotrifosfazen z trzema funkcyjnymi grupami końcowymi: synteza i charakterystyka struktury nowych policyklotrifosfazenów z grupami zasad Schiffa
    Autorzy:
    Al-Shukri, Salah Mahdi
    Mahmood, Ayad Tarik
    Al Hanbali, Othman A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1790060.pdf
    Data publikacji:
    2021
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
    Tematy:
    spirocyclotriphosphazene
    polycyclophosphazene
    poly(schiff-base)
    thermal stability
    flame retardancy
    spirocyklotrifosfazen
    policyklofosfazen
    poli(zasada Schiffa)
    stabilność termiczna
    ognioodporność
    Opis:
    A new tris-spiro-(3,4-dioxybenzaldehyde)cyclotriphosphazene [PNCHO] was synthesized from the condensation of hexachlorocyclotriphosphazene with 3,4-dihydroxybenzaldehyde in the presence of strong base. Further reaction of the trialdehydic cyclotriphosphazene based molecules [PNCHO] with three different dianilines (benzidine, 4,4’-methylenedianiline and 4,4′-Sulfonyldianiline) resulted in creation of a new poly(tris-spiro-3,4-dioxbenzene)cyclotriphosphazenes with Schiff-base groups [PNSB1-3]. The structures of [PNCHO] and the polycyclotriphosphazenes-schiff base derivatives were characterized by means of FTIR, 1H, 13C NMR and C.H.N elemental analysis. Differential scanning calorimetery (DSC) revealed a relatively high glass transition temperature (135−175°C) of obtained polymers. Thermal gravimetric analysis (TGA) exhibited their good thermal stability (up to 375°C). The char yield was about 36–42% at 700°C. All polymers were self-extinguishable as the LOI (Limiting Oxygen Index) values were above 26% and this meets with the V-0 and V-1, classification (UL-94). No fumes, soot, or toxic gases emission were observed during burning. The polymers obtained can be used as environmentally friendly, flame-retardant materials.
    Nowy tris-spiro-(3,4-dioksybenzaldehydo)cyklotrifosfazen [PNCHO] zsyntetyzowano w procesie kondensacji heksachlorocyklotrifosfazenu z 3,4-dihydroksybenzaldehydem w obecności silnej zasady. W wyniku reakcji trialdehydo cyklotrifosfazenów z trzema różnymi dianilinami (benzydyna, 4,4’-metylenodianilina i 4,4’-sulfonylodianilina) otrzymano poli(tris-spiro-3,4-dioksabenzeno)cyklotrifosfazeny z zasadami Schiffa [PNSB1-3]. PNCHO i pochodne policyklotrifosfazen-zasady Schiffa scharakteryzowano za pomocą analizy elementarnej (C, H, N), FTIR, 1H, 13C NMR. Metodą różnicowej kalorymetrii skaningowej (DSC) wykazano wysoką temperaturę zeszklenia (135−175°C) otrzymanych polimerów. Metodą analizy termograwimetrycznej (TGA) potwierdzono ich dobrą stabilność termiczną (do 375°C). Stopień zwęglenia po spaleniu wynosił w temp. 700°C ok. 36–42%. Wszystkie polimery były samogasnące, ponieważ wartości LOI (Limiting Oxygen Index) przekraczały 26%, co odpowiada klasie palności V-0 i V-1 (UL-94). Podczas spalania nie zaobserwowano emisji oparów, sadzy ani toksycznych gazów. Otrzymane polimery mogą znaleźć zastosowanie jako przyjazne dla środowiska materiały trudnopalne.
    Źródło:
    Polimery; 2021, 66, 6; 341--349
    0032-2725
    Pojawia się w:
    Polimery
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ranking criteria for assessment of municipal solid waste dumping sites
    Autorzy:
    Mahmood, K.
    Batool, S. A.
    Chaudhary, M. N.
    Ul-Haq, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/205345.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    MSW dumping facility
    hazard assessment
    ranking criteria
    geographic information system (GIS)
    remote
    sensing
    Opis:
    Priority wise channelization of resources is the key to successful environmental management, especially when funds are limited. The study in hand has successfully developed an algorithmic criterion to compare hazardous effects of Municipal Solid Waste (MSW) dumping sites quantitatively. It is a Multi Criteria Analysis (MCA) that has made use of the scaling function to normalize the data values, Analytical Hierarchy Process (AHP) for assigning weights to input parameters showing their relevant importance, and Weighted Linear Combination (WLC) for aggregating the normalized scores. Input parameters have been divided into three classes namely Resident’s Concerns, Groundwater Vulnerability and Surface Facilities. Remote Sensing data and GIS analysis were used to prepare most of the input data. To elaborate the idea, four dumpsites have been chosen as case study, namely Old-FSD, New-FSD, Saggian and Mahmood Booti. The comparison has been made first at class levels and then class scores have been aggregated into environmental normalized index for environmental impact ranking. The hierarchy of goodness found for the selected sites is New-FSD > Old-FSD > Mahmood Booti > Saggian with comparative scores of goodness to environment as 36.67, 28.43, 21.26 and 13.63 respectively. Flexibility of proposed model to adjust any number of classes and parameters in one class will be very helpful for developing world where availability of data is the biggest hurdle in research based environmental sustainability planning. The model can be run even without purchasing satellite data and GIS software, with little inaccuracy, using imagery and measurement tools provided by Google Earth.
    Źródło:
    Archives of Environmental Protection; 2017, 43, 1; 95-105
    2083-4772
    2083-4810
    Pojawia się w:
    Archives of Environmental Protection
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Measurement of Natural radioactivity in tap water samples for selected regions in Thi-Qar Governorate - Iraq
    Autorzy:
    Hadi, Hasan A.
    Karim, Mahmood S.
    Mahi, Ali T.
    Abood, Tareq H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1192660.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    (HPGe) detector
    Thi-Qar governorate
    tap water
    specific activity
    radionuclides
    Opis:
    In the present work, we have measured specific activity concentrations in ten tap water samples for selected regions in Thi-Qar governorate by using high purity germanium (HPGe) detector. The results have shown that, the specific activity, for 238U was ranged from (0.65±0.8 Bq/kg) in AL- Nasir region to (1.32±0.7.8 Bq/kg) in AL-Refai region, for 232Th the specific activity was ranged from (0.120±0.34 Bq/kg) in AL-Garraf region to (0.980±0.99 Bq/kg) in AL- Dwaya region, for 40K the specific activity was ranged from (13.33±3.6 Bq/kg) in AL-Nasir region to (38.54±6.2 Bq/kg) in (AL-Garraf) region, with an average values of (0.933±0.16 Bq/kg), (0.737±0.17 Bq/kg), (24.451±7.5Bq/kg), for 238U, 232Th and 40K, respectively. In order to asses the radiological hazards of the radioactivity in tap water, we have been calculated the parameters (Raeq , DƔ, AEDin , AEDout , EAD , Iɣ , Hin and Hex).
    Źródło:
    World Scientific News; 2016, 47, 2; 112-122
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of the etching time and current density on Capacitance-Voltage characteristics of P-type of porous silicon
    Autorzy:
    Hadi, Hasan A.
    Abood, Tareq H.
    Mohi, Ali T.
    Karim, Mahmood S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1178661.pdf
    Data publikacji:
    2017
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    electrochemical etching
    heterojunction
    porous silicon
    thin films
    Opis:
    In This paper, electrochemical etching teqniques was using to formation of nano crystalline porous silicon layer on p-type Si substrates. Measurement of capacitance – voltage characteristics at various etching time and current densities were used for calculated built in voltage and type of heterojunction. The built in voltage values were decreased with increasing etching time and current densities for both anisotype Al/PS/p-Si/Al heterojunction. These characteristics are interpreted by assuming the abrupt heterojunction model. The effect of different etching time and current densities on electrical properties of PS have been investigated.
    Źródło:
    World Scientific News; 2017, 67, 2; 149-160
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spatiotemporal monitoring of CO2 and CH4 over Pakistan using Atmospheric Infrared Sounder (AIRS)
    Autorzy:
    Mahmood, I.
    Iqbal, M.F.
    Shahzad, M.I.
    Waqas, A.
    Atique, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/11805.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Opis:
    Carbon dioxide (CO2), Methane (CH4) are two most potent greenhouse gases and are major source of climate change. Human activities particularly fossil fuels burning have caused considerable increase in atmospheric concentrations of greenhouse gases. CO2 contributes 60% of anthropogenic greenhouse effect whereas CH4 contributes 15%. Ice core records also show that the concentrations of Carbon dioxide and methane have increased substantially. The emission of these gases alters the Earth’s energy budget and are drivers of climate change. In the present study, atmospheric concentration of CO2 and CH4 over Pakistan is measured using Atmospheric Infrared Sounder (AIRS). Time series and time averaged maps are prepared to measure the concentrations of CO2 and CH4. The results show considerable increase in concentration of Carbon dioxide and methane. The substantial increase in these concentrations can affect human health, earth radiative balance and can damage crops.
    Źródło:
    International Letters of Natural Sciences; 2016, 58
    2300-9675
    Pojawia się w:
    International Letters of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Novel lignocellulosic wastes for comparative adsorption of Cr(VI): equilibrium kinetics and thermodynamic studies
    Autorzy:
    Haroon, H.
    Gardazi, S. M. H.
    Butt, T. A.
    Pervez, A.
    Mahmood, Q.
    Bilal, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/778473.pdf
    Data publikacji:
    2017
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    chromium VI
    equilibrium kinetics
    lignocellulosic waste adsorbents
    thermodynamics
    Opis:
    Cr(VI) adsorption was studied for abundantly available low-cost lignocellulosic adsorbents in Pakistan namely, tobacco stalks (TS), white cedar stem (WCS) and eucalyptus bark (EB). Several process variables like contact time, adsorbent dose, pH, metal concentration, particle size and temperature were optimized in batch mode. EB showed high Cr(VI) adsorption of 63.66% followed by WCS 62% and TS 57% at pH 2, which is higher than most of the reported literature. Langmuir isotherm (R2  = 0.999) was well fitted into the equilibrium Cr(VI) data of EB, suggesting homogeneous active sites and monolayer coverage of Cr(VI) onto the EB surface. Freundlich (R2  = 0.9982) isotherm was better fitted to the equilibrium data of TS and WCS, revealing the adsorption sites with heterogeneous energy distribution and multilayer Cr(VI) adsorption. Moreover, the Cr(VI) adsorption of studied adsorbents followed the pseudo-second order kinetic model. Thermodynamic properties were investigated in two temperature ranges, i.e., T1  (303–313 K) and T2  (313–323 K). TS and EB showed the exothermic at T1 and endothermic reactions at T2 with entropy controlled adsorption at the solid-liquid interface, and WCS exhibited an opposite thermal trend with decreasing disorderness at solid-liquid interface as temperature rises. Gibbs free energy (ΔG>0) confirmed the non-spontaneous adsorption process for all studied adsorbents.
    Źródło:
    Polish Journal of Chemical Technology; 2017, 19, 2; 6-15
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical investigation of convective heat transfer of single wall carbon nanotube nanofluid laminar flow inside a circular tube
    Autorzy:
    Saeed, Farqad Rasheed
    Jasim, Marwah A.
    Mahmood, Natheer B.
    Jaffar, Zahraa M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1845470.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    convective heat transfer
    reynolds number
    nanofluid
    single
    wall
    carbon
    nanotube
    SWCNT
    laminar flow
    Opis:
    This study presents the behavior of a single wall carbon nanotube (SWCNT)/water nanofluid for convective laminar flow inside a straight circular pipe heated by a constant heat flux. Five volume fractions of SWCNT were used to investigate their effect on the heat transfer coefficient, Nusselt number, temperature distribution and velocity field in comparison with pure water flow. One model for each property was tested to calculate the effective thermal conductivity, effective dynamic viscosity, and effective specific heat of the SWCNT/water mixture. The models were extracted from experimental data of a previous work. The outcomes indicate that the rheological behavior of SWCNT introduces a special effect on the SWCNT/water properties, which vary with SWCNT volume fraction. The results show an improvement in the heat transfer coefficient with increasing volume fraction of nanoparticles. The velocity of SWCNT/water nanofluid increased by adding SWCNT nanoparticles, and the maximum increase was registered at 0.05% SWCNT volume fraction. The mixture temperature is increased with the axial distance of the pipe but a reduction in temperature distribution is observed with the increasing SWCNT volume fraction, which reflects the effect of thermophysical properties of the mixture.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 2; 103-119
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    USE OF GLUTARIC ACID TO IMPROVE THE SOLUBILITY AND DISSOLUTION PROFILE OF GLIPIZIDE THROUGH PHARMACEUTICAL COCRYSTALLIZATION
    Autorzy:
    Batool, Fakhra
    Ahmad, Mahmood
    Minhas, Muhammad U.
    Khalid, Qandeel
    Idrees, Hafiz A.
    Khan, Fahad M.
    Powiązania:
    https://bibliotekanauki.pl/articles/895470.pdf
    Data publikacji:
    2019-02-28
    Wydawca:
    Polskie Towarzystwo Farmaceutyczne
    Tematy:
    FTIR
    SEM
    PXRD
    thermal analysis
    glipizide
    glutaric acid
    Opis:
    The purpose of current study was to improve the solubility and dissolution profile of BCS class-II drug Glipizide using glutaric acid as a coformer via various cocrystalization techniques i.e., dry grinding, liquid assisted grinding, slurry and solvent evaporation. Fourier Transform Infrared Spectroscopy (FTIR) was performed to determine the interaction between components of glipizide-glutaric acid (GPZ-GLU) cocrystals. Powder X-ray Diffraction (PXRD) studies confirmed the crystalline nature of formulated cocrystals. Scanning Electron Microscopy (SEM) revealed cylindrical to rectangular shape of cocrystals. Flow properties of GPZ-GLU cocrystals were evaluated by micromeritics analysis. Size and surface morphology was determined by zeta sizer analysis and optical microscopy. Differential scanning calorimetry (DSC) and Thermogravimetric (TGA) analysis were performed to determine the melting points as well as thermal stability of pure components and formulated GPZ-GLU cocrystals. In-vitro drug release studies were carried out using dissolution apparatus-II. GPZ-GLU cocrystals showed higher drug release at pH 6.8 as compared to pH 1.2. However, percent drug release of optimum formulations at pH 6.8 was determined as; 24%-92.2% (F3) and 12.0%-93.5% (F7). Solubility studies revealed improved solubility as compared to pure drug in water i.e., 53 folds and 54.27 folds from F3 and F7 cocrystals, respectively. Finally it was concluded that glutaric acid has improved the solubility and dissolution profile of glipizide. However, many cocrystal formers have been reported in literature that can be used to enhance the physicochemical properties as well as bioavailability of poorly soluble drugs via cocrystalization technique.
    Źródło:
    Acta Poloniae Pharmaceutica - Drug Research; 2019, 76, 1; 103-114
    0001-6837
    2353-5288
    Pojawia się w:
    Acta Poloniae Pharmaceutica - Drug Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental and Theoretical Investigation to Study the Molecular Structure, Electronic Properties, UV–Vis Spectra of Coumarin 102
    Autorzy:
    Mohi, Ali T.
    Abood, Tareq H.
    Hadi, Hasan A.
    Karim, Mahmood S.
    Mutlik, Falah A-H.
    Alwan, Tariq J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1178533.pdf
    Data publikacji:
    2017
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    DFT
    Ionization potential
    TDDFT
    electron affinity
    energy gap and UV spectra
    Opis:
    In this work, we study the structure, electronic properties and electronic spectra of Coumarin 102 (C102) dissolved in ethanol as an experimental-theoretical investigation. The various properties of the ground and excited electronic states of coumarins 102 using density functional theory (DFT) and time-dependent density functional theory (TDDFT) was calculated by the B3LYP density functional model with 6-31G(d,p) basis set by Gaussian 09 W program. Spectral characteristics of coumarin 102 have been probed into by methods of experimental UV-visible, and quantum chemistry. The UV spectrum was measured in Ethanol. The optimized structures, total energies, electronic states (HOMO- LUMO), energy gap, ionization potentials, electron affinities, chemical potential, global hardness, softness, global electrophilictity, dipole moment and electrostatic potential was calculated. were calculated. We find good agreement between experimental data of UV spectrum and TDDFT excitation energies.
    Źródło:
    World Scientific News; 2017, 70, 2; 216-229
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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