Dynamic characteristics and fatigue damage prediction of FRP strengthened marine riser

Islam, A.B.M. Saiful Techno-Press 2018 Ocean systems engineering Vol.8 No.1

Due to the escalation in hydrocarbon consumption, the offshore industry is now looking for advanced technology to be employed for deep sea exploration. Riser system is an integral part of floating structure used for such oil and gas extraction from deep water offering a system of drill twines and production tubing to spread the exploration well towards the ocean bed. Thus, the marine risers need to be precisely employed. The incorporation of the strengthening material, fiber reinforced polymer (FRP) for deep and ultra-deep water riser has drawn extensive curiosity in offshore engineering as it might offer potential weight savings and improved durability. The design for FRP strengthening involves the local design for critical loads along with the global analysis under all possible nonlinearities and imposed loadings such as platform motion, gravity, buoyancy, wave force, hydrostatic pressure, current etc. for computing and evaluating critical situations. Finite element package, ABAQUS/AQUA is the competent tool to analyze the static and dynamic responses under the offshore hydrodynamic loads. The necessities in design and operating conditions are studied. The study includes describing the methodology, procedure of analysis and the local design of composite riser. The responses and fatigue damage characteristics of the risers are explored for the effects of FRP strengthening. A detail assessment on the technical expansion of strengthening riser has been outlined comprising the inquiry on its behavior. The enquiry exemplifies the strengthening of riser as very potential idea and suitable in marine structures to explore oil and gas in deep sea.

Occurrence, clinical signs, postmortem lesions and etiology of enterotoxaemia in Black Bengal goats

Islam, K.B.M. Saiful,Rahman, Md. Siddiqur,Ershaduzzaman, Md.,Taimur, M.J.F.A.,Song, Hee-Jong The Korean Society of Veterinary Service 2008 韓國家畜衛生學會誌 Vol.31 No.4

A year round study was carried out to investigate the etiology, clinical signs, postmortem lesions and occurrence of naturally occurring enterotoxaemia in Black Bengal goats. Sixteen goats of different age and sex died in different seasons with sigh associated with enterotoxaemia made the materials of this study. Accidental access to large amount of concentrate was noted as one of the predisposing factors although few cases were reported to occur without known diet change. Younger animals(50%) and males(62.50%) were found more prone to the disease and it was likely to be more prevalent during winter(50%) followed by at rainy season(31.25%) and summer(18.75%). Diarrhoea(81.25%), dullness(56.25%), drooping of the ears(50%), anorexia(43.75%) were recorded as major clinical signs whereas enterocolitis(100%), lung edema(87.50%), fluid filled intestines(87.50%), enlarged mesenteric lymph nodes(56.52%) etc. were most common post mortem lesions found. A few cases showed lesions on heart(31.25%), brain(25%) and/or liver/spleen(18.75%) but no lesion was found on kidney. Thus the so called 'pulpy kidney' lesion was absent. Intestinal contents were subjected to conventional bacteriological culture based methods to identify the causal agents. Based on the morphological, cultural and biochemical properties the causal agent was identified as Clostridium perfringens. Despite the study was carried out at certain area it showed a clear picture of goat enterotoxaemia in terms of etiology, clinical signs, postmortem lesions and occurrence of goat enterotoxaemia in Bangladesh.

Ready mixed concrete behavior of granulated blast furnace slag contained cement

M. Razaul Karim,A. B. M. Saiful Islam,Faisal I. Chowdhury,Sarder Kashif Ur Rehman,Md. Rabiul Islam 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.2

Due to enhanced construction requirement, ready mixed concrete are being popular day by day. The current study aimed to develop ready mixed concrete using GBFS contained cement and determine its properties of fresh and hardened states. A real scale experiment was set up in a ready mixed plant for measuring workability and compressive strength. The workability was tested after mixing (within 5 minutes), 30, 60, 90, 120 and 150 minutes of the running of bulk carrier. The ready mixed carrier employed spinning motion i.e., rotating around its axis with 20 RPM and running on road with 1km/h speed. The mixing ratio of cement: sand:gravel, water to cement ratio, super plasticizer were, 1:1.73:2.47, 0.40 and 6% of cement, respectively. The chemical composition of raw material was determined using XRF and the properties of cements were measured according to ASTM standards. The experimental results confirm that the cement with composition of 6.89% of GBFS, 4% of Gypsum and 89.11% of clinker showed the good compressive strength and workability of concrete after 150 minutes of the spinning motion in bulk carrier.

Potential use of local waste scoria as an aggregate and SWOT analysis for constructing structural lightweight concrete

Islam, A.B.M. Saiful,Walid, Walid,Al-Kutti, A.,Nasir, Muhammad,Kazmi, Zaheer Abbas,Sodangi, Mahmoud Techno-Press 2022 Advances in materials research Vol.11 No.2

This study aims to investigate the influence of scoria aggregate (SA) and silica fume (SF) as a replacement of conventional aggregate and ordinary Portland cement (OPC), respectively. Three types of concrete were prepared namely normal weight concrete (NWC) using limestone aggregate (LSA) and OPC (control specimen), lightweight concrete (LWC) using SA and OPC, and LWC using SA and partial SF (SLWC). The representative workability and compressive strength properties of the developed concrete were evaluated, and the results were correlated with non-destructive ultrasonic pulse velocity and Schmidt hammer tests. The LWC and SLWC yielded compressive strength of around 30 MPa and 33 MPa (i.e., 78-86% of control specimens), respectively. The findings indicate that scoria can be beneficially utilized in the development of structural lightweight concrete. Present renewable sources of aggregate will preserve the natural resources for next generation. The newly produced eco-friendly construction material is intended to break price barriers in all markets and draw attraction of incorporating scoria based light weight construction in Saudi Arabia and GCC countries. Findings of the SWOT analysis indicate that high logistics costs for distributing the aggregates across different regions in Saudi Arabia and clients' resistant to change are among the major obstacles to the commercialized production and utilization of lightweight concrete as green construction material. The findings further revealed that huge scoria deposits in Saudi Arabia, and the potential decrease in density self-weight of structural elements are the major drivers and enablers for promoting the adoption of lightweight concrete as alternative green construction material in the construction sector.

A Non-Linear Exponential(NLINEX) Loss Function in Bayesian Analysis

Islam, A.F.M.Saiful,Roy, M.K.,Ali, M.Masoom The Korean Data and Information Science Society 2004 한국데이터정보과학회지 Vol.15 No.4

In this paper we have proposed a new loss function, namely, non-linear exponential(NLINEX) loss function, which is quite asymmetric in nature. We obtained the Bayes estimator under exponential(LINEX) and squared error(SE) loss functions. Moreover, a numerical comparison among the Bayes estimators of power function distribution under SE, LINEX, and NLINEX loss function have been made.

An Analytical Approach to Direct Torque and Flux Control of Interior Permanent Magnet Synchronous Machine for Deep Field Weakening Without Using Pre-calculated Lookup Tables

S M Showybul Islam Shakib,D. Xiao,R. Dutta,Kazi Saiful Alam,Ilham Osman,M. F. Rahman 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents an analytic approach to direct torque and flux controller (DTFC) for Interior permanent magnet synchronous machine (IPMSM) which includes deep flux weakening. Unlike the conventional lookup tables (LUTs) based DTFC, this paper proposes a direct mathematical calculation approach for the stator flux reference as well as the torque limit in field weakening (FW) and maximum-torque-per-voltage (MTPV) regions. The proposed method will thus allow flexibility of using online estimated machine parameters directly for an optimized IPMSM drive. This study also explores the voltage and current limit trajectories on a torque-flux linkage plane to operate the machine in deep field weakening. It incorporates maximumtorque- per-ampere (MTPA), FW, and MTPV trajectories control under voltage and current constraints. Experimental results are shown to verify the effectiveness of the proposed algorithm.

Implication of rubber- steel bearing nonlinear models on soft storey structures

A.B.M. Saiful Islam,Raja Rizwan Hussain,Mohammed Zamin Jumaat,Kh Mahfuz ud Darain 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.5

Soft storey buildings are characterised by having a storey that has a large amount of open space. This soft storey creates a major weak point during an earthquake. As the soft stories are typically associated with retail spaces and parking garages, they are often on the lower levels of tall building structures. Thus, when these stories collapse, the entire building can also collapse, causing serious structural damage that may render the structure completely unusable. The use of special soft storey is predominant in the tall building structures constructed by several local developers, making the issue important for local building structures. In this study, the effect of the incorporation of an isolator on the seismic behaviour of tall building structures is examined. The structures are subjected to earthquakes typical of the local city, and the isolator is incorporated with the appropriate isolator time period and damping ratio. A FEM-based computational relationship is proposed to increase the storey height so as to incorporate the isolator with the same time period and damping ratio for both a lead rubber bearing (LRB) and high-damping rubber bearing (HDRB). The study demonstrates that the values of the FEM-based structural design parameters are greatly reduced when the isolator is used. It is more beneficial to incorporate a LRB than a HDRB.

Incorporation preference for rubber-steel bearing isolation in retrofitting existing multi storied building

A.B.M. Saiful Islam,University of MalayaMohd Zamin Jumaat,Raja Rizwan Hussain,Md. Akter Hosen,Md. Nazmul Huda 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.4

Traditionally, multi-story buildings are designed to provide stiffer structural support to withstand lateral earthquake loading. Introducing flexible elements at the base of a structure and providing sufficient damping is an alternative way to mitigate seismic hazards. These features can be achieved with a device known as an isolator. This paper covers the design of base isolators for multi-story buildings in medium-risk seismicity regions and evaluates the structural responses of such isolators. The well-known tower building for police personnel built in Dhaka, Bangladesh by the Public Works Department (PWD) has been used as a case study to justify the viability of incorporating base isolators. The objective of this research was to establish a simplified model of the building that can be effectively used for dynamic analysis, to evaluate the structural status, and to suggest an alternative option to handle the lateral seismic load. A finite element model was incorporated to understand the structural responses. Rubber-steel bearing (RSB) isolators such as Lead rubber bearing (LRB) and high damping rubber bearing (HDRB) were used in the model to insert an isolator link element in the structural base. The nonlinearities of rubber-steel bearings were considered in detail. Linear static, linear dynamic, and nonlinear dynamic analyses were performed for both fixed-based (FB) and base isolated (BI) buildings considering the earthquake accelerograms, histories, and response spectra of the geological sites. Both the time-domain and frequency-domain approaches were used for dynamic solutions. The results indicated that for existing multi-story buildings, RSB diminishes the muscular amount of structural response compared to conventional non-isolated structures. The device also allows for higher horizontal displacement and greater structural flexibility. The suggested isolation technique is able to mitigate the structural hazard under even strong earthquake vulnerability.

Selection of Late Planting Potential Cultivars of Sweet Potato in Temperate Regions

A.F.M. Saiful Islam,Hiroaki Hirai,Yoshiaki Kitaya,Toru Kumagai 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Occurrence, clinical signs, postmortem Lesions and etiology of enterotoxaemia in Black Bengal goats

( K. B. M. Saiful Islam ),( Md. Siddiqur Rahman ),( Md. Ershaduzzaman ),( M. J. F. A. Taimur ),( Hee Jong Song ) 한국가축위생학회 2008 韓國家畜衛生學會誌 Vol.31 No.4

A year round study was carried out to investigate the etiology, clinical signs, postmortem lesions and occurrence of naturally occurring enterotoxaemia in Black Bengal goats. Sixteen goats of different age and sex died in different seasons with sigh associated with entero-toxaemia made the materials of this study. Accidental access to large amount of concentrate was noted as one of the predisposing factors although few cases were reported to occur without known diet change. Younger animals(50%) and males(62.50%) were found more prone to the disease and it was likely to be more prevalent during winter(50%) followed by at rainy season(31.25%) and summer(18.75%). Diarrhoea(81.25%), dullness(56.25%), drooping of the ears(50%), anorexia(43.75%) were recorded as major clinical signs whereas enterocolitis(100%), lung edema(87.50%), fluid filled intestines(87.50%), enlarged mesenteric lymph nodes(56.52%) etc. were most common post mortem lesions found. A few cases showed lesions on heart(31.25%), brain(25%) and/or liver/spleen(18.75%) but no lesion was found on kidney. Thus the so called ``pulpy kidney`` lesion was absent. Intestinal contents were subjected to conventional bacteriological culture based methods to identify the causal agents. Based on the morphological, cultural and biochemical properties the causal agent was identified as Clostridium perfringens. Despite the study was carried out at certain area it showed a clear picture of goat enterotoxaemia in terms of etiology, clinical signs, postmortem lesions and occurrence of goat enterotoxaemia in Bangladesh.