Abdikarim Ibrahim - Academia.edu (original) (raw)
Papers by Abdikarim Ibrahim
![Research paper thumbnail of A comparative analysis on the adequacy of the computer crimes act 1997 in Malaysia and the computer misuse act 1990 in United Kingdom in governing the issue of phishing / Munira Masood...[et al.]](https://attachments.academia-assets.com/106128814/thumbnails/1.jpg)
](The students/authors confirm that the work submitted is their own and that appropriate credit has... more The students/authors confirm that the work submitted is their own and that appropriate credit has been given where reference has been made to the work of others.
Applied Sciences
Recent advancements in deep reinforcement learning (DRL) have led to its application in multi-age... more Recent advancements in deep reinforcement learning (DRL) have led to its application in multi-agent scenarios to solve complex real-world problems, such as network resource allocation and sharing, network routing, and traffic signal controls. Multi-agent DRL (MADRL) enables multiple agents to interact with each other and with their operating environment, and learn without the need for external critics (or teachers), thereby solving complex problems. Significant performance enhancements brought about by the use of MADRL have been reported in multi-agent domains; for instance, it has been shown to provide higher quality of service (QoS) in network resource allocation and sharing. This paper presents a survey of MADRL models that have been proposed for various kinds of multi-agent domains, in a taxonomic approach that highlights various aspects of MADRL models and applications, including objectives, characteristics, challenges, applications, and performance measures. Furthermore, we pr...
Life and Medical Sciences
Carcinoid tumor is one of the rare gastrointestinal tumors. We present here; a case of 54 years o... more Carcinoid tumor is one of the rare gastrointestinal tumors. We present here; a case of 54 years old woman with complete stricture in the Small Bowel at the ileum level, caused by a carcinoid tumour who underwent a laparotomy. After resection of the tissue, histopathology was confirmed carcinoid tumor as the casual stricture. A such a typical presentation in patients not having a mass in radiological studies except signs and symptoms of bowel obstruction should raise suspicion of a carcinoid tumor.
International Journal of Case Reports and Images, 2017
International Journal of Case Reports and Images (IJCRI) is an international, peer reviewed, mont... more International Journal of Case Reports and Images (IJCRI) is an international, peer reviewed, monthly, open access, online journal, publishing high-quality, articles in all areas of basic medical sciences and clinical specialties. Aim of IJCRI is to encourage the publication of new information by providing a platform for reporting of unique, unusual and rare cases which enhance understanding of disease process, its diagnosis, management and clinico-pathologic correlations. IJCRI publishes Review Articles, Case Series, Case Reports, Case in Images, Clinical Images and Letters to Editor.
Institute of Transportation Studies, 2008
This report presents the results of construction, Heavy Vehicle Simulator (HVS) tests, deflection... more This report presents the results of construction, Heavy Vehicle Simulator (HVS) tests, deflection tests, post-HVS forensic testing, and analysis on dowel bar retrofitted (DBR) concrete pavement test sections at Palmdale, California. This project was originally proposed in 2000 by the Caltrans Headquarters Division of Design. Benefits expected from this research are to provide Caltrans with information about design and construction of DBR to help determine where DBR may be a cost-effective strategy for rehabilitating rigid pavement and to help obtain best performance where DBR is selected as the preferred rehabilitation strategy. HVS Tests: Pavement sections include retrofitted joints and transverse cracks with three and four epoxy-coated steel dowels, four hollow stainless steel dowels, and four fiber-reinforced polymer dowels per wheelpath. HVS and FWD results at Palmdale also are compared with the results from previous HVS testing. HVS testing showed that joint performance with four epoxy-coated steel dowels was generally the best of all the sections in terms of load transfer efficiency (LTE) and joint deflection. Three dowels per wheelpath was substantially worse than the other test sections that had four dowels per wheelpath in terms of load transfer efficiency (LTE), however, it was substantially better than before DBR. Joint deflections were substantially better for four epoxy-coated steel dowels per wheelpath than for the other sections. HVS results show that for each of the DBR alternatives, LTE was not substantially affected by heavy HVS loading and that the slabs failed by fatigue cracking before LTE dropped substantially. FWD Tests: The primary performance criteria are LTE and vertical deflection of the joints. Larger joint vertical deflections and lower LTE are strongly correlated with increased rate of faulting and roughness development. FWD deflection measurements agree with those under HVS wheel loading, showing that LTE was substantially improved by DBR and was not substantially affected by HVS trafficking. Results are presented showing sensitivity of deflections and LTE to dowel type, number of dowels per wheelpath, and slab temperature based on FWD measurements. Construction and materials: Observations about DBR construction and materials presented indicate variability in depth of dowel bar placement, overall good condition of the slots and grout, and test results showing that the grout met Caltrans specifications for flexural and compressive strength.
Institute of Transportation Studies, 2005
This document compares the results of flexural fatigue tests performed on experimental concrete b... more This document compares the results of flexural fatigue tests performed on experimental concrete beams made of the standard Caltrans concrete mix and five other fast-setting mixes. The three research objectives were: to investigate the fatigue characteristics of the fast-setting mixes, to compare the fatigue life of all the mixes tested, and to contrast this experiment's results with those of similar published studies.
Institute of Transportation Studies, 2004
Our objective is to demonstrate the use of Computational Fluid Dynamic (CFD) in building applicat... more Our objective is to demonstrate the use of Computational Fluid Dynamic (CFD) in building applications. In particular, CFD has been used for temperature and airflow predictions of building spaces conditioned using Under Floor Air Distribution (UFAD) System. The space used is an instrumented laboratory room (old daycare center) located at the University of Wyoming. The use of the CFD simulation results provides insightful analyses of the UFAD design and diffuser locations. The k-ε turbulent model was employed to simulate the environment above an Under-Floor Air Distribution (UFAD) system, where the air is supplied using different configurations of several diffuser locations. Mesh generation was conducted using a pre-processor program, called GAMBIT. The CFD results were obtained using the program FLUENT and show flow and thermal patterns, using temperature and heat flux boundary conditions obtained experimentally. These boundary conditions have been used to predict the nature of conv...
This document compares the results of flexural fatigue tests performed on experimental concrete b... more This document compares the results of flexural fatigue tests performed on experimental concrete beams made of the standard Caltrans concrete mix and five other fast-setting mixes. The three research objectives were: to investigate the fatigue characteristics of the fast-setting mixes, to compare the fatigue life of all the mixes tested, and to contrast this experiment's results with those of similar published studies. The experimental concrete samples included the standard Caltrans mix (using Portland cement type I/II) and five fast-setting mixes that used one of three cements: Portland cement type III, calcium sulfoaluminate, or calcium aluminate. Beams were fabricated from each mixture were used to determine the materials' flexural strength (or modulus of rupture) and fatigue life (or number of cycles to failure) at stress ratio levels of 0.70 and 0.85, and, in most cases 0.75. Three subsequent data analyses compared the number of cycles to failure of each mix at each stress ratio level, applied regression to compare the fatigue life of each fastsetting mix with the Caltrans standard mix, and applied regression to compare this study's results with common models for beam flexural fatigue life found in the literature. The study's main conclusions were: (a) fast-setting concrete mixes present similar or higher fatigue resistance than the standard Caltrans type, (b) at a stress ratio 0.70 all the mixes presented similar fatigue resistance, but at a stress ratio of 0.85 the Type III Portland cement mix displayed the eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. longest fatigue life, and (c) linear regression curves generated by the tested mixes compared better to the "zero maintenance" model-the most common fatigue-life model used in concrete pavement engineering-than they did to the NCHRP 1-26 model.
… Research Record: Journal …, 2003
The California Department of Transportation uses dowel bar retrofit (DBR) as a rehabilitation str... more The California Department of Transportation uses dowel bar retrofit (DBR) as a rehabilitation strategy for concrete pavements. Two test sec-tions were retrofitted with dowel bars and a third section was designated as a control on US-101 near Ukiah, California. All three sections ...
Journal of Materials in Civil Engineering, Oct 1, 2008
In concrete pavements, steel dowels are exposed to a particularly aggressive environment that lea... more In concrete pavements, steel dowels are exposed to a particularly aggressive environment that leads to depassivation and greatly reduces the corrosion initiation stage. Aggressive agents such as chlorides and CO 2 have easy access to the dowels through pavement joints and, consequently, the corrosion performance of the system depends largely on the properties of the steel dowel being used. This study investigates the corrosion performance of several types of steel dowels embedded in concrete and subjected to accelerated ...
Draft Report prepared for the California Department of Transportation, Pavement Research Center, Institute of Transportation Studies, 2004
EXECUTIVE SUMMARY Dowels are used in jointed concrete pavements to provide load transfer across t... more EXECUTIVE SUMMARY Dowels are used in jointed concrete pavements to provide load transfer across transverse joints. Their use reduces vertical deflections that cause faulting and stresses that cause corner and longitudinal cracking by transferring part of the load to the unloaded slab. However, if corrosion of the dowels occurs, a number of problems can arise that can compromise the performance of the pavement and lead to premature failure. These problems include:
California Department of Transportation, May 1, 2004
The primary purpose of the work presented in this report is to provide Caltrans with information ... more The primary purpose of the work presented in this report is to provide Caltrans with information regarding the accuracy and feasibility of the maturity method for the measurement of concrete flexural strength. Information is also provided regarding use of the maturity method for measurement of compressive strength.
eScholarship provides open access, scholarly publishing services to the University of California ... more eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide.
The students/authors confirm that the work submitted is their own and that appropriate credit has... more The students/authors confirm that the work submitted is their own and that appropriate credit has been given where reference has been made to the work of others.
Applied Sciences
Recent advancements in deep reinforcement learning (DRL) have led to its application in multi-age... more Recent advancements in deep reinforcement learning (DRL) have led to its application in multi-agent scenarios to solve complex real-world problems, such as network resource allocation and sharing, network routing, and traffic signal controls. Multi-agent DRL (MADRL) enables multiple agents to interact with each other and with their operating environment, and learn without the need for external critics (or teachers), thereby solving complex problems. Significant performance enhancements brought about by the use of MADRL have been reported in multi-agent domains; for instance, it has been shown to provide higher quality of service (QoS) in network resource allocation and sharing. This paper presents a survey of MADRL models that have been proposed for various kinds of multi-agent domains, in a taxonomic approach that highlights various aspects of MADRL models and applications, including objectives, characteristics, challenges, applications, and performance measures. Furthermore, we pr...
Life and Medical Sciences
Carcinoid tumor is one of the rare gastrointestinal tumors. We present here; a case of 54 years o... more Carcinoid tumor is one of the rare gastrointestinal tumors. We present here; a case of 54 years old woman with complete stricture in the Small Bowel at the ileum level, caused by a carcinoid tumour who underwent a laparotomy. After resection of the tissue, histopathology was confirmed carcinoid tumor as the casual stricture. A such a typical presentation in patients not having a mass in radiological studies except signs and symptoms of bowel obstruction should raise suspicion of a carcinoid tumor.
International Journal of Case Reports and Images, 2017
International Journal of Case Reports and Images (IJCRI) is an international, peer reviewed, mont... more International Journal of Case Reports and Images (IJCRI) is an international, peer reviewed, monthly, open access, online journal, publishing high-quality, articles in all areas of basic medical sciences and clinical specialties. Aim of IJCRI is to encourage the publication of new information by providing a platform for reporting of unique, unusual and rare cases which enhance understanding of disease process, its diagnosis, management and clinico-pathologic correlations. IJCRI publishes Review Articles, Case Series, Case Reports, Case in Images, Clinical Images and Letters to Editor.
Institute of Transportation Studies, 2008
This report presents the results of construction, Heavy Vehicle Simulator (HVS) tests, deflection... more This report presents the results of construction, Heavy Vehicle Simulator (HVS) tests, deflection tests, post-HVS forensic testing, and analysis on dowel bar retrofitted (DBR) concrete pavement test sections at Palmdale, California. This project was originally proposed in 2000 by the Caltrans Headquarters Division of Design. Benefits expected from this research are to provide Caltrans with information about design and construction of DBR to help determine where DBR may be a cost-effective strategy for rehabilitating rigid pavement and to help obtain best performance where DBR is selected as the preferred rehabilitation strategy. HVS Tests: Pavement sections include retrofitted joints and transverse cracks with three and four epoxy-coated steel dowels, four hollow stainless steel dowels, and four fiber-reinforced polymer dowels per wheelpath. HVS and FWD results at Palmdale also are compared with the results from previous HVS testing. HVS testing showed that joint performance with four epoxy-coated steel dowels was generally the best of all the sections in terms of load transfer efficiency (LTE) and joint deflection. Three dowels per wheelpath was substantially worse than the other test sections that had four dowels per wheelpath in terms of load transfer efficiency (LTE), however, it was substantially better than before DBR. Joint deflections were substantially better for four epoxy-coated steel dowels per wheelpath than for the other sections. HVS results show that for each of the DBR alternatives, LTE was not substantially affected by heavy HVS loading and that the slabs failed by fatigue cracking before LTE dropped substantially. FWD Tests: The primary performance criteria are LTE and vertical deflection of the joints. Larger joint vertical deflections and lower LTE are strongly correlated with increased rate of faulting and roughness development. FWD deflection measurements agree with those under HVS wheel loading, showing that LTE was substantially improved by DBR and was not substantially affected by HVS trafficking. Results are presented showing sensitivity of deflections and LTE to dowel type, number of dowels per wheelpath, and slab temperature based on FWD measurements. Construction and materials: Observations about DBR construction and materials presented indicate variability in depth of dowel bar placement, overall good condition of the slots and grout, and test results showing that the grout met Caltrans specifications for flexural and compressive strength.
Institute of Transportation Studies, 2005
This document compares the results of flexural fatigue tests performed on experimental concrete b... more This document compares the results of flexural fatigue tests performed on experimental concrete beams made of the standard Caltrans concrete mix and five other fast-setting mixes. The three research objectives were: to investigate the fatigue characteristics of the fast-setting mixes, to compare the fatigue life of all the mixes tested, and to contrast this experiment's results with those of similar published studies.
Institute of Transportation Studies, 2004
Our objective is to demonstrate the use of Computational Fluid Dynamic (CFD) in building applicat... more Our objective is to demonstrate the use of Computational Fluid Dynamic (CFD) in building applications. In particular, CFD has been used for temperature and airflow predictions of building spaces conditioned using Under Floor Air Distribution (UFAD) System. The space used is an instrumented laboratory room (old daycare center) located at the University of Wyoming. The use of the CFD simulation results provides insightful analyses of the UFAD design and diffuser locations. The k-ε turbulent model was employed to simulate the environment above an Under-Floor Air Distribution (UFAD) system, where the air is supplied using different configurations of several diffuser locations. Mesh generation was conducted using a pre-processor program, called GAMBIT. The CFD results were obtained using the program FLUENT and show flow and thermal patterns, using temperature and heat flux boundary conditions obtained experimentally. These boundary conditions have been used to predict the nature of conv...
This document compares the results of flexural fatigue tests performed on experimental concrete b... more This document compares the results of flexural fatigue tests performed on experimental concrete beams made of the standard Caltrans concrete mix and five other fast-setting mixes. The three research objectives were: to investigate the fatigue characteristics of the fast-setting mixes, to compare the fatigue life of all the mixes tested, and to contrast this experiment's results with those of similar published studies. The experimental concrete samples included the standard Caltrans mix (using Portland cement type I/II) and five fast-setting mixes that used one of three cements: Portland cement type III, calcium sulfoaluminate, or calcium aluminate. Beams were fabricated from each mixture were used to determine the materials' flexural strength (or modulus of rupture) and fatigue life (or number of cycles to failure) at stress ratio levels of 0.70 and 0.85, and, in most cases 0.75. Three subsequent data analyses compared the number of cycles to failure of each mix at each stress ratio level, applied regression to compare the fatigue life of each fastsetting mix with the Caltrans standard mix, and applied regression to compare this study's results with common models for beam flexural fatigue life found in the literature. The study's main conclusions were: (a) fast-setting concrete mixes present similar or higher fatigue resistance than the standard Caltrans type, (b) at a stress ratio 0.70 all the mixes presented similar fatigue resistance, but at a stress ratio of 0.85 the Type III Portland cement mix displayed the eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. longest fatigue life, and (c) linear regression curves generated by the tested mixes compared better to the "zero maintenance" model-the most common fatigue-life model used in concrete pavement engineering-than they did to the NCHRP 1-26 model.
… Research Record: Journal …, 2003
The California Department of Transportation uses dowel bar retrofit (DBR) as a rehabilitation str... more The California Department of Transportation uses dowel bar retrofit (DBR) as a rehabilitation strategy for concrete pavements. Two test sec-tions were retrofitted with dowel bars and a third section was designated as a control on US-101 near Ukiah, California. All three sections ...
Journal of Materials in Civil Engineering, Oct 1, 2008
In concrete pavements, steel dowels are exposed to a particularly aggressive environment that lea... more In concrete pavements, steel dowels are exposed to a particularly aggressive environment that leads to depassivation and greatly reduces the corrosion initiation stage. Aggressive agents such as chlorides and CO 2 have easy access to the dowels through pavement joints and, consequently, the corrosion performance of the system depends largely on the properties of the steel dowel being used. This study investigates the corrosion performance of several types of steel dowels embedded in concrete and subjected to accelerated ...
Draft Report prepared for the California Department of Transportation, Pavement Research Center, Institute of Transportation Studies, 2004
EXECUTIVE SUMMARY Dowels are used in jointed concrete pavements to provide load transfer across t... more EXECUTIVE SUMMARY Dowels are used in jointed concrete pavements to provide load transfer across transverse joints. Their use reduces vertical deflections that cause faulting and stresses that cause corner and longitudinal cracking by transferring part of the load to the unloaded slab. However, if corrosion of the dowels occurs, a number of problems can arise that can compromise the performance of the pavement and lead to premature failure. These problems include:
California Department of Transportation, May 1, 2004
The primary purpose of the work presented in this report is to provide Caltrans with information ... more The primary purpose of the work presented in this report is to provide Caltrans with information regarding the accuracy and feasibility of the maturity method for the measurement of concrete flexural strength. Information is also provided regarding use of the maturity method for measurement of compressive strength.
eScholarship provides open access, scholarly publishing services to the University of California ... more eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide.