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    Torrefaction of Pelletized Oil Palm Empty Fruit Bunches

    Ahmad, Arshad, Johari, Anwar, Oladokun, Olagoke
    arXiv.org, May 10, 2015
    © ProQuest LLC All rights reserved, Engineering Database, Publicly Available Content Database, ProQuest Engineering Collection, ProQuest Technology Collection, ProQuest SciTech Collection, Materials Science & Engineering Database, ProQuest Central (new), ProQuest Central Korea, SciTech Premium Collection, Technology Collection, ProQuest Central Essentials, ProQuest One Academic, Engineering Collection (ProQuest)
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    Title: Torrefaction of Pelletized Oil Palm Empty Fruit Bunches
    Author: Ahmad, Arshad; Johari, Anwar; Oladokun, Olagoke
    Contributor: Oladokun, Olagoke (pacrepositoryorg)
    Subject: Calorific Value ; Solid Fuels ; Briquets ; Pyrolysis ; Drying
    Description: The torrefaction of oil palm Empty Fruit Bunch (EFB) briquettes was examined in this study. The results indicate that temperature significantly influenced the mass yield, energy yield and heating value of oil palm empty fruit bunch (OPEFB) briquettes during torrefaction. The solid uniform compact nature of EFB briquettes ensured a slow rate of pyrolysis or devolatization which enhanced torrefaction. The mass yield decreased from 79.70 % to 43.03 %, energy yield from 89.44 % to 64.27 % during torrefaction from 250 {\deg}C to 300 {\deg}C. The heating value (HHV) of OPEFB briquettes improved significantly from 17.57 MJ/kg to 26.24 MJ/kg after torrefaction at 300 {\deg}C for 1 hour. Fundamentally, the study has highlighted the effects of pelletization and torrefaction on solid fuel properties of oil palm EFB briquettes and its potential as a solid fuel for future thermal applications.
    Is part of: arXiv.org, May 10, 2015
    Identifier: 2331-8422 (E-ISSN)

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    Kinetic Study on a Commercial Amorphous Hydrocracking Catalyst by Weighted Lumping Strategy

    Sadighi, Sepehr, Ahmad, Arshad, Irandoukht, Akbar
    International Journal of Chemical Reactor Engineering, 2010, Vol.8(1) [Peer Reviewed Journal]
    Walter de Gruyter GmbH
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    Title: Kinetic Study on a Commercial Amorphous Hydrocracking Catalyst by Weighted Lumping Strategy
    Author: Sadighi, Sepehr; Ahmad, Arshad; Irandoukht, Akbar
    Publisher: De Gruyter
    Subject: Hydrocracking ; Vacuum Gas Oil ; Lump Kinetic Model ; Amorphous
    Description: Hydrocracking is an important upgrading process in the petroleum refinery, and it is generally used to process feedstocks ranging from vacuum gas oil (VGO) to vacuum residue. In this work, hydrocracking of VGO using a dual functional amorphous catalyst was carried out at a pilot scale unit under the following reaction conditions: liquid hourly space velocity (LHSV) from 1 to 1.5 hr-1 and reaction temperatures of 360-440°C at the constant pressure and hydrogen to oil, 156 bar and 1780 Nm3/m3, respectively. The effluent of the reactor was characterized to dry gas, naphtha, kerosene, diesel and unconverted VGO or residue. The pilot tests demonstrated that performing experiments beyond the temperature, recommended by catalyst vendor, lead the process to unstable hydrocracking. To describe the yield of hydrocracking products a five-lump discrete lumping approach with ten reactions was proposed. At first, the kinetic model contained twenty kinetic constants which were estimated by using the conventional objective function. The estimated parameters showed that the tendency of the catalyst to convert VGO to gas and naphtha was negligible whilst rate constants for hydrocracking of VGO to middle distillates were considerably high which was compatible with the nature of amorphous hydrocracking catalysts. After evaluating the magnitude of reaction rates and eliminating the ignorable constants, the network was reduced to six reactions in which only nine parameters were needed. The predictions indicated that the latter network could fit the yield of products more acceptable as if the average absolute deviation between experimental and calculated yields was descended from 16.25% to 12.6%. Then, to have a better prediction, a weighted objective function was used in which weight factors were calculated by a proposed weighted least square expression. The results confirmed that this approach could reduce average absolute deviation of model to 10.75%, and it created a fairly even distribution of deviation between hydrocracking products.
    Is part of: International Journal of Chemical Reactor Engineering, 2010, Vol.8(1)
    Identifier: 1542-6580 (E-ISSN); 10.2202/1542-6580.2193 (DOI)

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    4-Lump kinetic model for vacuum gas oil hydrocracker involving hydrogen consumption

    Sadighi, Sepehr, Ahmad, Arshad, Rashidzadeh, Mehdi
    Korean Journal of Chemical Engineering, 2010, Vol.27(4), pp.1099-1108 [Peer Reviewed Journal]

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    Primary amyloidoma of chest wall--a rare condition

    Kumar, Suresh, Kumar, Surender, Ahmad, Arshad, Kumar, Awanish
    BMJ case reports, 27 March 2012, Vol.2012 [Peer Reviewed Journal]
    MEDLINE/PubMed (U.S. National Library of Medicine)
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    Title: Primary amyloidoma of chest wall--a rare condition
    Author: Kumar, Suresh; Kumar, Surender; Ahmad, Arshad; Kumar, Awanish
    Subject: Thoracic Wall ; Amyloidosis -- Diagnosis
    Description: Organ specific amyloidosis has been shown to be confined to various organs like liver, lung, spleen, urinary bladder and gastro-intestinal tract, but amyloidoma or tumoural amyloidosis of chest wall with no evidence of systemic amyloidosis is an extremely rare presentation and only two cases have been reported till now. The authors report a case of chest wall amyloidoma with review of literature.
    Is part of: BMJ case reports, 27 March 2012, Vol.2012
    Identifier: 1757-790X (E-ISSN); 22605798 Version (PMID); 10.1136/bcr.01.2012.5552 (DOI)

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    Comparison of Lumping Approaches to Predict the Product Yield in a Dual Bed VGO Hydrocracker

    Sadighi, Sepehr, Ahmad, Arshad, Shirvani, Mansoor
    International Journal of Chemical Reactor Engineering, 2012, Vol.9(1) [Peer Reviewed Journal]
    Walter de Gruyter GmbH
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    Title: Comparison of Lumping Approaches to Predict the Product Yield in a Dual Bed VGO Hydrocracker
    Author: Sadighi, Sepehr; Ahmad, Arshad; Shirvani, Mansoor
    Publisher: De Gruyter
    Subject: Hydrotreating ; Hydrocracking ; Lump Kinetic Model ; Hydrogen Consumption ; Dual Bed Hydrocracking Reactor
    Description: In this research, to predict the product yields of a pilot scale VGO hydrocracking reactor charged with mono functional hydrotreating and hydrocracking catalysts, two different four-lump models are developed. The first one, called combined bed model, is a simplex in which there is no boundary between hydrotreating and hydrocracking reactions through the reactor. The second one, called dual bed model, is a rigorous model in which hydrogen consumption and hydrotreating reactions are included. In this way, the reactor is subdivided into two different layers, so the effect of hydrotreating reactions on the hydrocracking section can be considered. Results show that the absolute average deviation (AAD%) of the yield prediction for the combined bed and the dual bed models are 8.23 percent and 5.87 percent, respectively. The main reason for the lower average deviation of the dual bed model is its higher accuracy to predict the yield of gas which is also the major advantage of this approach. However, the simplicity of the combined bed model can make it more applicable and attractive, especially when hydrogen consumption as well as sulfur, nitrogen and aromatic specifications of the feed and products are not accessible.
    Is part of: International Journal of Chemical Reactor Engineering, 2012, Vol.9(1)
    Identifier: 1542-6580 (E-ISSN); 10.1515/1542-6580.2519 (DOI)

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    Effect of Lump Partitioning on the Accuracy of a Commercial Vacuum Gas Oil Hydrocracking Model

    Sadighi, Sepehr, Ahmad, Arshad, Masoudian, Seyed Kamal
    International Journal of Chemical Reactor Engineering, 2012, Vol.10(1) [Peer Reviewed Journal]
    Walter de Gruyter GmbH
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    Title: Effect of Lump Partitioning on the Accuracy of a Commercial Vacuum Gas Oil Hydrocracking Model
    Author: Sadighi, Sepehr; Ahmad, Arshad; Masoudian, Seyed Kamal
    Publisher: De Gruyter
    Subject: Hydrocracking ; Lump Kinetic Model ; Vacuum Gas Oil ; Partitioning ; Separation
    Description: In an industrial hydrocracking plant, except to the reactor, the separation section can affect the accuracy of the developed mathematical model. In this study, two combined-bed six and seven-lump kinetic models for the hydrocracking of vacuum gas oil in a real refinery are developed and their accuracies for the prediction of product yields are compared. In the six-lump model, the engaged components are selected according to the actual products of the plant, but the seven-lump one is included of lumps which are partitioned based on the specified initial and final boiling points.For both approaches, a complete kinetic network with the catalyst-decay functions is considered. It is found that over a 17-month period of operation from the start of run, the average absolute deviation (AAD%) of the six-lump and the seven-lump models for the yield prediction are 20.51% and 5.21%, respectively for all products. Additionally, the sum of residuals for the seven-lump model has been appreciably decreased in comparison to the six-lump one. Therefore, it is confirmed that partitioning of the products to the lumps with specific boiling points can acceptably decrease the deviation of the prediction. So it is conclusive that including the operation of the separation section in commercial models can effectively increase the accuracy of the model and smooth the prediction error.
    Is part of: International Journal of Chemical Reactor Engineering, 2012, Vol.10(1)
    Identifier: 1542-6580 (E-ISSN); 10.1515/1542-6580.2616 (DOI)

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    Resistance to Change of Academics towards Accreditation

    Kadzrina Abdul Kadir, Darwina Ahmad Arshad, Johanim Johari
    Journal of Business and Social Review in Emerging Economies, 01 December 2016, Vol.2(2), pp.127-134 [Peer Reviewed Journal]
    Directory of Open Access Journals (DOAJ)
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    Title: Resistance to Change of Academics towards Accreditation
    Author: Kadzrina Abdul Kadir; Darwina Ahmad Arshad; Johanim Johari
    Description: When universities makes the decision to go for accreditation to improve performance standards, there has been an impact on academics who are involved in the process. The literature suggests that for accreditation such as business programs such as AACSB, both positive and negative impact could occur for academics. This paper gives an overview on three areas of literature that is pertinent to this topic: resistance to change, accreditation impact on the university, and accreditation impact on business academics with balanced scorecard to measure accreditation impact.
    Is part of: Journal of Business and Social Review in Emerging Economies, 01 December 2016, Vol.2(2), pp.127-134
    Identifier: 2519-089X (ISSN); 2519-0326 (E-ISSN); 10.26710/jbsee.v2i2.29 (DOI)

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    Evisceration of the small bowel through a perforated and prolapsed sigmoid colon: an unusual presentation of rectal prolapse

    Ahmad, Arshad, Kumar, Suresh, Sonkar, Abhinav Arun, Kumar, Sanjeev
    BMJ case reports, 15 April 2016, Vol.2016, pp.10.1136/bcr-2016-214811 [Peer Reviewed Journal]
    MEDLINE/PubMed (U.S. National Library of Medicine)
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    Title: Evisceration of the small bowel through a perforated and prolapsed sigmoid colon: an unusual presentation of rectal prolapse
    Author: Ahmad, Arshad; Kumar, Suresh; Sonkar, Abhinav Arun; Kumar, Sanjeev
    Subject: Colon, Sigmoid ; Intestine, Small ; Intestinal Perforation -- Complications ; Rectal Prolapse -- Complications ; Sigmoid Diseases -- Complications
    Description: Spontaneous prolapse of the sigmoid colon and evisceration of the small bowel through a rupture in the rectosigmoid is a rare presentation. We report a case of a 60-year-old man presenting with massive small bowel evisceration through a perforation in a prolapsed sigmoid colon. The patient had a 2-year history of rectal prolapse. He was also incontinent for flatus and liquid stool. There was no other significant medical history. After reduction of the small intestine, a large perforation was seen in the prolapsed sigmoid colon. The sigmoid colon was identified by presence of appendices epiploicae and taeniae coli. After initial resuscitation, an emergency laparotomy was performed. The perforated sigmoid colon was resected and a Hartmann's colostomy was created. This resulted in complete recovery. Reversal of the Hartmann's colostomy was performed after 6 weeks.
    Is part of: BMJ case reports, 15 April 2016, Vol.2016, pp.10.1136/bcr-2016-214811
    Identifier: 1757-790X (E-ISSN); 27084900 Version (PMID); 10.1136/bcr-2016-214811 (DOI)

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    Comparative Analysis of Doppler Guided Hemorrhoidal Artery Ligation (DG-HAL) & Infrared Coagulation (IRC) in Management of Hemorrhoids

    Ahmad, Arshad, Kant, Rama, Gupta, Avneet
    Indian Journal of Surgery, 2013, Vol.75(4), pp.274-277 [Peer Reviewed Journal]

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    Thermogravimetric and Kinetic Analyses of Oil Palm Empty Fruit Bunch (OPEFB) Pellets Using the Distributed Activation Energy Model

    Nyakuma, Bemgba, Ahmad, Arshad, Johari, Anwar, Abdullah, Tuan
    Journal of Physical Science, 2016, Vol.27(3), pp.67-83 [Peer Reviewed Journal]
    © ProQuest LLC All rights reserved, Engineered Materials Abstracts, Solid State and Superconductivity Abstracts, METADEX, Materials Science Database, Advanced Technologies & Aerospace Database, Engineering Database, East & South Asia Database, Publicly Available Content Database, Advanced Technologies Database with Aerospace, Materials Research Database, Technology Research Database, ProQuest Engineering Collection, ProQuest Advanced Technologies & Aerospace Collection, ProQuest Materials Science Collection, ProQuest Technology Collection, ProQuest SciTech Collection, Materials Science & Engineering Database, ProQuest Central (new), ProQuest Central Korea, SciTech Premium Collection, Technology Collection, ProQuest Central Essentials, ProQuest Central China, ProQuest One Academic, Advanced Technologies & Aerospace Index (ProQuest), Materials Science Index (ProQuest), Materials Science Collection (ProQuest), Engineering Collection (ProQuest)
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    Title: Thermogravimetric and Kinetic Analyses of Oil Palm Empty Fruit Bunch (OPEFB) Pellets Using the Distributed Activation Energy Model
    Author: Nyakuma, Bemgba; Ahmad, Arshad; Johari, Anwar; Abdullah, Tuan
    Subject: Pyrolysis ; Reaction Kinetics ; Fruits ; Activation Energy ; Thermal Degradation ; Palm ; Decomposition ; Pellets ; Miscellaneous Sciences (So) ; General and Nonclassified (MD) ; General and Nonclassified (Ep) ; General and Nonclassified (Ed) ; General and Nonclassified (EC) ; Thermogravimetry ; Oil Palm ; Empty Fruit Bunches ; Pellets ; Energy Model;
    Description: The thermal degradation behaviour and decomposition kinetics of oil palm empty fruit bunch (OPEFB) pellets were investigated using a thermogravimetric analyser and the distributed activation energy model (DAEM). The OPEFB pellets were heated from 30°C to 1000°C at three different heating rates (5, 10, 20°C min^sup -1^) under a nitrogen atmosphere. The thermogravimetric-derivative thermogravimetric (TG-DTG) curves revealed that the non-isothermal decomposition of OPEFB pellets occurred in the following three stages: drying (35°C-175°C), active pyrolysis (200°C-370°C) and passive pyrolysis (370°C-1000°C), which resulted in the loss of moisture, volatile matter and char, respectively. The distributed activation energy model was subsequently used to determine the apparent activation energies (E) and pre-exponential factors (A), which ranged from 37.89 kJ mol^sup -1^ to 234.05 kJ mol^sup -1^ and from 2.05 × 10^sup 2^ min^sup -1^ to 3.54 × 10^sup 18^ min^sup -1^, respectively, for conversions...
    Is part of: Journal of Physical Science, 2016, Vol.27(3), pp.67-83
    Identifier: 16753402 (ISSN); 21804230 (E-ISSN); 10.21315/jps2016.27.3.5 (DOI)