On simple estimation technique for the reliability of exponential lifetime model

Al-Hemyari, Z.A.,Al-Saidy, Obaid M.,Al-Ali, A.R. The Korean Reliability Society 2013 International Journal of Reliability and Applicati Vol.14 No.2

Exponential distribution plays a key role in engineering reliability and its applications. The exponential failure model has been studied for years. This article introduces two new preliminary test estimators for the reliability function (R(t)) in complete and censored samples from the exponential model with the use of a prior estimation (${\theta}_0$) of the mean (${\theta}$). The proposed preliminary test estimators are studied and compared numerically with the existing estimators. Computer-intensive calculations for bias and relative efficiency show that for, different values of levels of significance and for varying constants involved in the proposed estimators, the proposed estimators are far better than classical and existing estimators.

Influence of porosity on the hygro-thermo-mechanical bending response of an AFG ceramic-metal plates using an integral plate model

Mohammed A. Al-Osta,Hayat Saidi,Abdelouahed Tounsi,S.U. Al-Dulaijan,M.M. Al-Zahrani,Alfarabi Sharif,Abdeldjebbar Tounsi 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.4

In this project, the hygro-thermo-mechanical bending behavior of perfect and imperfect advanced functionally graded (AFG) ceramic-metal plates is analytically investigated using an integral plate model for the first time. The plate is assumed to be supported by a two-parameter elastic foundation. Because of the technical problems encountered in the manufacture of AFG, porosities and micro-voids can occur in AFG specimens, which can result in reduced density and strength of materials. Thus, due to the presence of porosity, a modified rule of mixture is adopted to predict the material properties of the AFG plates. The governing equations are deduced by adopting the "principle of virtual work" and an integral plate model. The analytical Navier's method is considered to solve the obtained differential equations for simply supported AFG porous plate. The results obtained are checked by comparing them for non-porous and porous AFG plates with those available in the open literature. Finally, this work will help us to design advanced functionally graded materials to ensure better durability and efficiency for hygro-thermal environments.

On simple estimation technique for the reliability of exponential lifetime model

Z. A. Al-Hemyari,Obaid M. Al-Saidy,A. R. Al-Ali 한국신뢰성학회 2013 International Journal of Reliability and Applicati Vol.14 No.2

Exponential distribution plays a key role in engineering reliability and its applications. The exponential failure model has been studied for years. This article introduces two new preliminary test estimators for the reliability function ( R(t) ) in complete and censored samples from the exponential model with the use of a prior estimation ( θ0 ) of the mean ( θ ) . The proposed preliminary test estimators are studied and compared numerically with the existing estimators. Computer-intensive calculations for bias and relative efficiency show that for, different values of levels of significance and for varying constants involved in the proposed estimators, the proposed estimators are far better than classical and existing estimators.

Influences of porosity distributions and boundary conditions on mechanical bending response of functionally graded plates resting on Pasternak foundation

Moustafa Guellil,Hayat Saidi,Fouad Bourada,Abdelmoumen Anis Bousahla,Abdelouahed Tounsi,Mesfer Mohammad Al-Zahrani,Muzamal Hussain,S. R. Mahmoud 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.1

In this paper, a higher order shear deformation theory for bending analysis of functionally graded plates resting on Pasternak foundation and under various boundary conditions is exposed. The proposed theory is based on the assumption that porosities can be produced within functionally graded plate which may lead to decline in strength of materials. In this research a novel distribution of porosity according to the thickness of FG plate are supposing. Governing equations of the present theory are derived by employing the virtual work principle, and the closed-form solutions of functionally graded plates have been obtained using Navier solution. Numerical results for deflections and stresses of several types of boundary conditions are presented. The exactitude of the present study is confirmed by comparing the obtained results with those available in the literature. The effects of porosity parameter, slenderness ratio, foundation parameters, power law index and boundary condition types on the deflections and stresses are presented.

Improvement of bearing capacity of footing on soft clay grouted with lime-silica fume mix

Fattah, Mohammed Y.,Al-Saidi, A'amal A.,Jaber, Maher M. Techno-Press 2015 Geomechanics & engineering Vol.8 No.1

In this study, lime (L), silica fume (SF), and lime-silica fume (L-SF) mix have been used for stabilizing and considering their effects on the soft clay soil. The improvement technique adopted in this study includes improving the behaviour, of a square footing over soft clay through grouting the clay with a slurry of lime-silica fume before and after installation of the footing. A grey-colored densified silica fume is used. Three percentages are used for lime (2%, 4% and 6%) and three percentages are used for silica fume (2.5%, 5%, 10%) and the optimum percentage of silica fume is mixed with the percentages of lime. Several tests are made to investigate the soil behaviour after adding the limeand silica fume. For grouting the soft clay underneath and around the footing, a 60 ml needle was used as a liquid tank of the lime-silica fume mix. Slurried silica fume typically contains 40 to 60% silica fume by mass. Four categories were studied to stabilize soft clay before and after footing construction and for each category, the effectiveness of grouting was investigated; the effect of injection hole spacing and depth of grout was investigated too. It was found that when the soft clay underneath or around a footing is injected by a slurry of lime-silica fume, an increase in the bearing capacity in the range of (6.58-88)% is obtained. The footing bearing capacity increases with increase of depth of grouting holes around the footing area due to increase in L-SF grout. The grouting near the footing to a distance of 0.5 B is more effective than grouting at a distance of 1.0 B due to shape of shear failure of soft clay around the footing.

Ion pairing based polyurethane foam sorbent packed column combined with inductively coupled plasma–optical emission spectrometry for sensitive determination and chemical speciation of bismuth(III & V) in water

M.S. El-Shahawi,A.A. Al-Sibaai,A.S. Bashammakh,H. Alwael,H.M. Al-Saidi 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.28 No.-

The sorption profile of trace concentrations of bismuth(III) species from aqueous KI–H2SO4 media ontothe ion pairing procaine hydrochloride (PQ+.Cl ) based polyurethane foam (PUFs) was studied. A dual–mode of bismuth(III) sorption as a ternary complex ion associate [PQ+.BiI4] involving absorption due toa ‘‘weak base anion exchanger’’ and an added component for ‘‘surface adsorption’’ seems the proposedmechanism for bismuth(III) retention. The capacity of bismuth(III) sorption was found equal40.05 1.10 mg g 1. Complete separation of spiked bismuth(III) at various concentrations (5–15 mg mL 1)1) from water onto the proposed sorbent packed columns at 5 mL min 1 flow rate was successfully achieved. The retained bismuth(III) species were recovered quantitatively from the sorbent packed columns(98.4 2.4%, n = 5) with HNO3 (1.0 mol L 1). Bismuth(V) after reduction to Bi(III) was also preconcentrated,recovered from the sorbent packed column and subsequently analyzed by inductively coupled plasma–optical emission spectrometry (ICP–OES). The height equivalent to the theoretical plates (HETP), number ofplates (N), critical and breakthrough capacities of sorbent packed column towards bismuth(III) retentionwere evaluated. Based on these results, a simple and sensitive PQ+.Cl –PUF packed column was developed fordetermination and speciation of trace concentrations of bismuth(III & V) species in water by ICP–OES. Thelimits of detection (LOD) and quantification (LOQ) of Bi(III) were found 0.09 and 0.30 mg L 1, respectively. The relative standard deviation (RSD) for 5 replicates of 50 ng L 1 Bi at 2.0 mL min 1 flow was 3.7%. Theproposed column was validated and applied for the preconcentration, separation and subsequentdetermination of analyte in Environmental water reference material (TMDW) and water samples. Theresults were found to be in good agreement with the CRM at the 95% confidence level.

Investigation on the flexural behaviour of ferrocement pipes and roof panels subjected to bending moment

Alnuaimi A.S.,Hago A.W.,Al-Jabri K.S.,Al-Saidy A.H. 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.4

This paper presents experimental results on the behaviour and ultimate load of fifteen pipes and six roof panels made of ferrocement. Additional results from three roof panels, carried out by others, are also compared with this research results. OPC cement, natural sand and galvanised iron wire mesh were used for the construction of 20 mm thick specimens. The pipe length was 2 m and roof panel length was 2.1 m. The main variables studied were the number of wire mesh layers which were 1, 2, 3, 4 and 6 layers, the inner pipe diameter which were 105, 210 and 315 mm, cross sectional shape of the panel which were channel and box sections and the depth of the edge beam which were 95 mm and 50 mm. All specimens were simply supported and tested for pure bending with test span of 600 mm at mid-span. Tests revealed that increasing the number of wire mesh layers increases the flexural strength and stiffness. Increasing the pipe diameter or depth of edge beam of the panel increases the cracking and ultimate moments. The change in the pipe diameter led to larger effect on ultimate moment than the effect of change in the number of wire mesh layers. The box section showed behaviour and strength similar to that of the channel with same depth and number of wire mesh layers.

Adsorption of lisinopril and chlorpheniramine from aqueous solution on dehydrated and activated carbons

El-Said I. El-Shafey,Haider A. J. Al-Lawati,Wafa S. H. Al-Saidi 한국탄소학회 2016 Carbon Letters Vol.19 No.-

Date palm leaflets were used as a precursor to prepare dehydrated carbon (DC) via phosphoric acid treatment at 150°C. DC, acidified with H3PO4, was converted to activated carbon (AC) at 500°C under a nitrogen atmosphere. DC shows very low surface area (6.1 m2/g) while AC possesses very high surface area (829 m2/g). The removal of lisinopril (LIS) and chlorpheniramine (CP) from an aqueous solution was tested at different pH, contact time, concentration, and temperature on both carbons. The optimal initial pH for LIS removal was 4.0 and 5.0 for DC and AC, respectively. However, for CP, initial pH 9.0 showed maximum adsorption on both carbons. Adsorption kinetics showed faster removal on AC than DC with adsorption data closely following the pseudo second order kinetic model. Adsorption increases with temperature (25°C–45°C) and activation energy (Ea) is in a range of 19–25 kJ mol/L. Equilibrium studies show higher adsorption on AC than DC. Thermodynamic parameters show that drug removal is endothermic and spontaneous with physical adsorption dominating the adsorption process. Column adsorption data show good fitting to the Thomas model. Despite its very low surface area, DC shows ~70% of AC drug adsorption capacity in addition of being inexpensive and easily prepared.

Association of Benign Prostate Hyperplasia with Polymorphisms in VDR, CYP17, and SRD5A2 Genes among Lebanese Men

El Ezzi, Asmahan Ali,Zaidan, Wissam Rateeb,El-Saidi, Mohammed Ahmed,Al-Ahmadieh, Nabil,Mortenson, Jeffrey Benjamin,Kuddus, Ruhul Haque Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.3

Background: The aim of the study was to investigate any associations between benign prostate hyperplasia (BPH) and single nucleotide polymorphisms (SNPs) in the VDR gene (FokI, BsmI, ApaI and Taq${\alpha}$I loci) and the CYP17 gene (MspA1I locus), as well as TA repeat polymorphism in SRD5A2 gene among Lebanese men. Materials and Methods: DNA extracted from blood of 68 subjects with confirmed BPH and 79 age-matched controls was subjected to PCR/PCR-restriction fragment length polymorphism analysis. The odds ra=tio (OR) of having a genotype and the relative risk (RR) of developing BPH for having the genotype were calculated and the alleles were designated risk-bearing or protective. Results: Our data indicated that the A and B alleles of the VDR ApaI and BsmI SNPs were highly associated with increased risk of BPH (p=0.0168 and 0.0002, respectively). Moreover, 63% of the controls compared to 43% of the subjects with BPH were homozygous for none of the risk-bearing alleles (p=0.0123) whereas 60% of the controls and 28% of the subjects with BPH were homozygous for two or more protective alleles (p<0.0001). Conclusions: For the first time, our study demonstrated that ApaI and BsmI of the VDR gene are associated with risk of BPH among Lebanese men. Our study also indicated that overall polymorphism profile of all the genes involved in prostate physiology could be a better predictor of BPH risk.

A new method for analysis of sunset yellow in food samples based on cloud point extraction prior to spectrophotometric determination

M.S. El-Shahawi,A. Hamza,A.A. Al-Sibaai,A.S. Bashammakh,H.M. Al-Saidi 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2

A simple new micelle mediated preconcentration method was developed for analysis of sunset yellow (SY) prior to its spectrophotometric determination. The method was based upon cloud point extraction of the ion associate of SY and trioctylamine (TOA) in HCl–Triton X-100. In the surfactant phase the SY species react with TOA yielding hydrophobic ion associate of SY-+TOA+. The distribution coefficient of SY between surfactant-rich phase and aqueous phase was approximately 104. Validation was tested by comparing the results with standard HPLC. Isotherm and thermodynamic parameters, chemical equilibrium, extraction constants and stiochiometry of the associate were assigned.