for Journals by Title or ISSN for Articles by Keywords help
 Subjects -> ENGINEERING (Total: 2270 journals)     - CHEMICAL ENGINEERING (191 journals)    - CIVIL ENGINEERING (183 journals)    - ELECTRICAL ENGINEERING (99 journals)    - ENGINEERING (1199 journals)    - ENGINEERING MECHANICS AND MATERIALS (390 journals)    - HYDRAULIC ENGINEERING (55 journals)    - INDUSTRIAL ENGINEERING (64 journals)    - MECHANICAL ENGINEERING (89 journals) ENGINEERING (1199 journals)                  1 2 3 4 5 6 | Last
 Arabian Journal for Science and Engineering   [SJR: 0.345]   [H-I: 20]   [5 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1319-8025    Published by Springer-Verlag  [2329 journals]
• Microstructure and Wear Properties of Laser-Cladded cBN/Ti $$_{3}$$ 3 Al
on Pure Titanium
• Authors: K. K. Sobiyi; E. T. Akinlabi
Abstract: In order to improve the tribological properties of titanium alloys at high temperature, the possibility of producing Ti $$_{3}$$ Al intermetallic with the addition of ceramic (cBN) coatings on titanium substrate using laser technique cladding was investigated. cBN is generally known for its high hot hardness, wear resistance and chemical stability. Laser cladding is an emerging material processing technique which is an efficient and cost-effective technique for improving the surface properties of general metallic materials. This paper presents the effects of laser cladding on the phase combination, microstructure, hardness and wear resistance of titanium aluminide/cBN IMC composites at different variations in quantity of cBN in the composite. Optical microscopy, X-ray diffraction and scanning electron microscopy with EDX were used for characterising the microstructure of the coating. In addition, the composite coating was subjected to wear testing using the ball-on-disc, friction and wear apparatus. The XRD results revealed phases with small cBN, $$\hbox {Ti}_{2}\hbox {N}$$ and $$\hbox {TiB}_{2}$$ peaks in addition to the rich $$\gamma$$ -Ti, $$\alpha 2\hbox {-Ti}_{3}\hbox {Al}$$ and TiAl intermetallics phases in the coatings after cladding process, whereas the microstructure of the cBN cladded layer contained partially melted cBN grains evenly dispersed within the laths of alpha Widmanstätten phase in the form of dendrites, precipitate of $$\alpha _{2}\hbox {-Ti}_{3}\hbox {Al}$$ and spherical-shaped pure titanium. The effect of the addition of cBN into $$\hbox {Ti}_{3}\hbox {Al}$$ alloy at increasing weight percentages showed an improvement in the hardness and wear resistance of the coatings. The increase is attributed to reacted boron nitrides particles with titanium, being distributed uniformly in the intermetallic matrix.
PubDate: 2017-05-20
DOI: 10.1007/s13369-017-2585-0

• Effect of External Perimeter on Flexural Strength of FDM Build Parts
• Authors: Swayam Bikash Mishra; Rameez Malik; S. S. Mahapatra
Abstract: Current manufacturing trend adopts newer technology that can reduce both the design and manufacturing lead time in order to face the challenging demands of the customer in an effective manner. In this regard, rapid prototyping technology, among all newly developed technologies, is reliable one because it is capable of manufacturing accurate and durable parts with 3D complex geometry within a stipulated time with less material waste. In this research work, effect of six relevant controllable input parameters (contour number or external perimeter, layer thickness, raster width, part orientation, air gap and raster angle) on flexural strength of the fused deposition modelling (FDM) build parts is analysed. Experimentation has been carried out using face-centred central composite design to reduce the number of experimentation. Contour number appears to be more influencing parameter because it helps to move the stress concentration zone from outer edge to the centre avoiding premature failure of the specimen. The study develops a statistically valid empirical model relating flexural strength with process parameters to ease prediction of flexural strength by tool engineers. Scanning electron microscope micrographs are used to explain the microstructure behaviour of FDM build parts when subjected to three point bend test. Finally, one nature-inspired metaheuristic approach known as Firefly algorithm is adopted to obtain optimal parameter setting for improving the flexural strength.
PubDate: 2017-05-20
DOI: 10.1007/s13369-017-2598-8

• A Capacitively Coupled Discharge Operating on Pure Water Vapor and Mixture
with Helium at Low and Close to Atmospheric Pressure
• Authors: Ziane Kechidi; Ahmed Hafid Belbachir; Abdelatif Tahraoui
Abstract: A one-dimensional fluid model has been developed and used to investigate a capacitively coupled discharge operating on a pure water vapor and on a mixture of water with helium. These models incorporate 29 main species and 81 dominant reaction channels. The effects of gas pressure and gap distance on the production of some species are discussed. The simulation results reveal that the plasma ignition in a pure water vapor can only be reached at low pressure when all dominant reactions are included in the model. The main mechanism by which the plasma ignition is suppressed may be attributed to the high rate of electron cooling. It is worth indicating that the creation rates of the vibrationally and rotationally excited states in water vapor compared to ionization are much more higher than they are in noble gases, such as argon or helium. As a result, this might be the main reason why the ignition of He plasma is easier when applying the same operating parameters. Therefore, two approaches are suggested to overcome this difficulty. The first one lies in decreasing the gas pressure to around $$10^3$$ Pa, and the gap distance to 0.5 mm. And the second one is by adding a small fraction (5%) of $$\mathrm{H}_2\mathrm{O}$$ to (95%) of helium and keeping the gap distance at 1 mm. The input parameters for plasma ignition have been identified, and the density profiles of the main species are reported and discussed.
PubDate: 2017-05-20
DOI: 10.1007/s13369-017-2601-4

• The Role of Cationic Coagulant-to-Cell Interaction in Dictating the
Flocculation-Aided Sedimentation of Freshwater Microalgae
• Authors: Pey Yi Toh; Nurfarah Farhana Azenan; Liherng Wong; Yin Sim Ng; Lee Muei Chng; JitKang Lim; Derek Juinn Chieh Chan
Abstract: The coagulant chitosan and poly(diallyldimethylammonium chloride) (PDDA) were proven effective to aid the sedimentation of microalgal cells through electrostatic patch flocculation. A total amount of 30 mg/L chitosan and PDDA can achieve cell separation efficiency of $$96.7 \pm 0.7$$ and $$98.4 \pm 1.0$$ %, respectively. The chitosan outperformed PDDA and promoted 4.4 times faster rate of cell sedimentation than the self-sedimentation rate of cells. The chitosan employed the mechanism of charge neutralization to form larger flocs, while the PDDA that favored the formation of loops and tails protruding away from cell surface employed the bridging mechanism to form flocs. The rate of cell sedimentation induced by chitosan was the highest at pH 7, 8 (control) and 9 compared to that of PDDA, where the cell flocculation by using chitosan was dominated by charge neutralization mechanism at pH 7 and 8 (control), while the cell flocculation was mainly driven by bridging mechanism at pH 9. This result shows that the chitosan is feasible in the harvesting of freshwater microalgae without the need of pH adjustment. Therefore, the chitosan was proven more reliable and time effective than the PDDA in harvesting the freshwater Chlorella sp. without the need of pH adjustment.
PubDate: 2017-05-20
DOI: 10.1007/s13369-017-2584-1

• Smooth Integration of Gansu Wind Farm into the Grid Using the Stator
Flux-Oriented Vector Method and Fuzzy Logic Control
• Authors: Mostafa Kheshti; Xiaoning Kang; Yasenjiang Jiarula
Abstract: Gansu province wind energy potential in China is around 237 GW. According to the schedule, 20 GW wind energy is connected to the grid by 2020. However, there is a chance of instability in the presence of big intermittency. To integrate this huge generated wind power, a reliable control strategy is required. The proposed portable power plant (PPP) energy storage system is fully compatible with a smart grid and mitigates the dispatching complexity and provides better designing and implementation of Gansu wind farm in China. In a two-way power flow, when the generation is bigger than the load demand, the additional power is stored in the PPP for future use, and when the demand is higher than the total generation, the stored power is applied to feed the grid. Also the PPP can charge the grid during peak demand periods or when the local network is stressed. An intelligent controller is linked with PPP to monitor the power flow. The stator flux-oriented vector method is used for modeling the system. Then, a fuzzy controller is applied to adjust the modulation index of PWM inverter and also uses energy storage units to stabilize the output of the power plant. Real field data of the Gansu wind farm with 24-h horizon have been applied on the proposed system. The results show the high performance of the fuzzy-based PPP system in the presence of fluctuations and increase the efficiency of the power system by storing energy through PPP. With a large-scale plan for application of smart grid and renewable energy sources in China, this paper introduces an essential step of this vision to provide a feasible framework for future large-scale smart grid projects in China as well as stable operation of Gansu wind farm as the biggest wind farm in mainland when it is completed.
PubDate: 2017-05-20
DOI: 10.1007/s13369-017-2596-x

• A Heuristic-Based Approach for Dynamic VMs Consolidation in Cloud Data
Centers
• Authors: Monir Abdullah; Kuan Lu; Philipp Wieder; Ramin Yahyapour
Abstract: Cloud computing providers have to deal with the energy-performance trade-off: minimizing energy consumption, while meeting service level agreement (SLA) requirements. This paper proposes a new heuristic approach for the dynamic consolidation of virtual machines (VMs) in cloud data centers. The fast best-fit decreasing (FBFD) algorithm for intelligent VMs allocating into hosts and dynamic utilization rate (DUR) algorithm for utilization space and VM migration are successfully proposed. We performed simulations using PlanetLab and GWDG data center workloads to compare our approach against the existing models. It has been observed that the FBFD heuristic algorithm produces better results compared to modified BFD algorithm in terms of energy consumption and SLA violation. Additionally, the time complexity of FBFD algorithm is significantly improved from the order of O( $$m\,*\,n$$ ) to O( $$m\,*\,\log _2{n}$$ ). Furthermore, leaving some rates of capacity in the physical machines by the proposed DUR algorithm for VMs to be extended reduces the number of migrations which in turn improves the energy consumption and SLA violation. Our heuristic approach is evaluated using CloudSim and the results show that it performs better than the current state-of-the-art approaches.
PubDate: 2017-05-20
DOI: 10.1007/s13369-017-2580-5

• Intelligent Distributed Control Techniques for Effective Current Sharing
and Voltage Regulation in DC Distributed Systems
• Authors: Shivam; Ratna Dahiya
Abstract: The droop control method is a basic technique for parallel operation of source converters. The cable line resistance of source converters is one of the causes for circulating current, degradation of load sharing, and poor voltage regulation in DC microgrid application. The control objective of microgrid is to minimize trade-off between bus voltage regulation and effective current sharing. The distributed control technique based on droop control is superior among other control technique in terms of expandability and reliability. This paper presents a distributed control technique which not only helps an effective solution for parallel operation of source converters, but also facilitates availability of maximum power to the load. The droop resistance of distributed controller is adjusted by using a fuzzy inference system in order to reduce the bus voltage degradation. This proposed scheme offers simplicity and robust control over the existing distributed control scheme. The performance of the DC microgrid which consists of three source converters with different cable line resistances and common load is verified in the MATLAB/Simulink environment.
PubDate: 2017-05-20
DOI: 10.1007/s13369-017-2576-1

• Measuring Object-Oriented Class Cohesion Based on Complex Networks
• Authors: Aihua Gu; Xiaofeng Zhou; Zonghua Li; Qinfeng Li; Lu Li
Abstract: Class cohesion has an immediate impact on maintainability, modifiability and understandability of the software. Here, a new metric of cohesion based on complex networks (CBCN) for measuring connectivity of class members was developed mainly relying on calculating class average clustering coefficient from graphs representing connectivity patterns of the various class members. In addition, the CBCN metric was assessed with theoretical validation according to four properties (nonnegativity and normalization, null and maximum values, monotonicity, cohesive modules) of the class cohesion theory. Based on data comparison with existing seventeen typical class cohesion metrics of class cohesion for a system, the CBCN metric was superior to others. Applying the CBCN metric to three open source software systems to calculate class average clustering coefficients, we found that understanding, modification and maintenance of classes in an open software system could be likely less difficult compared with those of others. Three open software systems have power-law distributions for the class average clustering coefficient, which makes possible the further understanding of the cohesion metric based on complex networks.
PubDate: 2017-05-20
DOI: 10.1007/s13369-017-2588-x

• Development of a New Correlation for Bubble Point Pressure in Oil
Reservoirs Using Artificial Intelligent Technique
• Authors: Salaheldin Elkatatny; Mohamed Mahmoud
Abstract: Accurate determination of the bubble point pressure (BPP) is extremely important in several applications in oil industry. In reservoir engineering applications the BPP is an essential input for the reservoir simulation and reservoir management strategies. Also, in production engineering the BPP determines the type of the inflow performance relationship that describes the reservoir production performance. Accurate estimation of the BPP will eliminate the risk of producing in two-phase region. Current correlations can be used to determine the BPP with high errors, and this will lead to poor reservoir management. Artificial intelligent tools used in the previous studies did not disclose the models they developed, and they stated the models as black box. The aim of this research is to develop a new empirical correlation for BPP prediction using artificial intelligent techniques (AI) such as artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), and support vector machine (SVM). For the first time we extracted the weights and the biases from AI models and form a new mathematical model for BPP prediction. The results obtained showed that the ANN model was able to estimate the BPP with high accuracy (correlation coefficient of 0.988 and average absolute error percent of 7.5%) based on the specific gravity of gas, the dissolved gas to oil ratio, the oil specific gravity, and the temperature of the reservoir as compared with ANFIS and SVM. The developed mathematical model from the ANN model outperformed the previous AI models and the empirical correlations for BPP prediction. It can be used to predict the BPP with a high accuracy (the average absolute error (3.9%) and the coefficient of determination ( $$R^{2})$$ of 0.98).
PubDate: 2017-05-19
DOI: 10.1007/s13369-017-2589-9

• Soft Expansive Soil Improvement by Eco-Friendly Waste and Quick Lime
• Authors: Jahangir Khazaei; Hossein Moayedi
Abstract: Expansive soils are being a source of risk to the population since it finally causes heavy economic losses, great damage to buildings and infrastructure. Current study focused on the feasibility of using waste from petrochemical plant (here called waste) as a stabilizer. The waste was provided from the process of water softening in petrochemical units. A complete set of laboratory tests were conducted to investigate on the effect of an eco-friendly waste and quick lime on stabilization of the expansive soil. For each of the introduced additives, treated samples containing 4, 6, 8, 10 and 12% concentration were prepared. The results of compaction, swelling measurement, Atterberg limits, and unconfined compression strength (UCS) tests indicated a reduction in swelling potential. This phenomena was contributed to the marked increase in UCS and shear strength of improved samples by waste and lime. The results unveiled that the new eco-friendly waste showed excellent function when compared to the conventional lime and it could provide desired geotechnical properties in soft expansive soil.
PubDate: 2017-05-18
DOI: 10.1007/s13369-017-2590-3

• A Novel, Efficient, Robust, and Blind Imperceptible 3D Anaglyph Image
Watermarking
• Authors: Hidangmayum Saxena Devi; Khumanthem Manglem Singh
Abstract: This paper proposes a novel, robust and efficient blind three-dimensional anaglyph image-watermarking scheme for copyright protection which utilizes the nonsubsampled contourlet transform and principal component analysis for embedding and extracting a binary watermark. The binary watermark is encrypted or scrambled using Arnold transform so as to give security and embedded using principal component analysis into the selected subband of the nonsubsampled contourlet-transformed 3D anaglyph image. Nonsubsampled contourlet transform is used due to its varying properties so as to resist against intentional image processing attacks. Principal component analysis is used in decorrelating the data. The proposed system is tested using Middlebury stereo dataset and experimental results show that the proposed scheme is highly imperceptible and has better performance than the existing anaglyph watermarking schemes in terms of both robustness and imperceptibility.
PubDate: 2017-05-10
DOI: 10.1007/s13369-017-2531-1

• Fixed-Bed Adsorption of Ranitidine Hydrochloride Onto Microwave
Assisted—Activated Aegle marmelos Correa Fruit Shell: Statistical
Optimization and Breakthrough Modelling
• Authors: N. Sivarajasekar; N. Mohanraj; R. Baskar; S. Sivamani
Abstract: In this study, the feasibility of using microwave-irradiated Aegle marmelos Correa fruit shell was investigated in a fixed-bed column towards sorptive removal of ranitidine hydrochloride (RH) from simulated aqueous solution. Characterizations of adsorbent such as SEM, point of zero charge, BET surface area, Boehm surface functional groups, thermal and elemental analysis were carried out. Box–Behnken response surface methodology was utilized to optimize the process parameters such as influent flow rate (2.5–4.5 ml min−1), initial RH concentration (100–200 mg l−1), adsorbent particle size (0.082–0.20 mm), and fixed-bed height (5–10 cm). The highest fixed-bed adsorptive removal of RH at optimum conditions viz. bed height 9.19 cm, initial RH concentration 184.94 mg l−1, flow rate 3.76 ml min−1 and adsorbent particle size 0.2 mm was estimated to be 72.86%. Fixed-bed adsorption experiments were carried out at optimum conditions obtained at different bed heights, and the data obtained were fitted into different kinetic models to predict the applicable breakthrough curve model. Dose–response model was observed to be the best suited model for mathematical description of RH removal in fixed-bed column studies over other selected models.
PubDate: 2017-05-05
DOI: 10.1007/s13369-017-2565-4

• Quantification of Software Code Coverage Using Artificial Bee Colony
Optimization Based on Markov Approach
• Authors: Muthusamy Boopathi; Ramalingam Sujatha; Chandran Senthil Kumar; Srinivasan Narasimman
Abstract: Software test suite generation and development of techniques to optimize the test suite are vital parts of the software development life cycle. In this paper, a combination of Markov chain and artificial bee colony (ABC) optimization techniques are adopted to attain the software code coverage. Initially, dd-graph is captured from the control flow graph of the source code and is represented as a Markov chain. The number of paths is obtained based on linear code sequence and jump (LCSAJ) coverage. LCSAJ is used to reduce the number of independent paths as compared to paths obtained by basis path testing. Automatic test cases are generated and based on the operation profile of the test suite; transition probabilities are obtained using gcov analysis tool. Further, ABC optimization is adopted to ensure software code coverage. The initial population is randomly selected from the test suite and populated for subsequent generations using the ABC algorithm. The test cases are generated for three mixed data type variables, namely integer, float and Boolean. The quality of the test cases is improved during every iteration of ABC optimization and traversed through number of LCSAJ-based independent paths thereby ensuring software code coverage. Finally, software code coverage is quantified using the fitness/happiness value computed as a product of node coverage and the corresponding transition probability values based on the path covered.
PubDate: 2017-05-05
DOI: 10.1007/s13369-017-2554-7

• Microstructural and Mechanical Investigation of NiTi Intermetallics
Produced by Hot Deformation Technique
• Authors: Sinan Aksöz
Abstract: This work has been carried out to bring an innovative approach to the difficulties encountered in the production of NiTi shape memory alloys by powder metallurgy (PM). For this purpose, new binder system, which was water soluble, was used for production of NiTi green parts. The green parts were sintered at $$1200\,{^{\circ }}\hbox {C}$$ for 60 min, and then red parts were deformed at $$1000\,{^{\circ }}\hbox {C}$$ for 40 and 50% deformation ratios. To observe the characterization of the microstructure and hot deformation effects, X-ray diffraction, scanning electron microscopy, mapping, microhardness and density measurements were applied to the samples. Experimental results show that the rhombohedral phase (space group R3), which was a lenticular disk-like morphology (disks), was detected at $$1200\,{^{\circ }}\hbox {C}$$ sintered PM parts. 551HV microhardness and $$5.85\,\hbox {g/cm}^{3}$$ density values could be achieved with the 50% hot deformation ratio. Furthermore, intermetallic components such as $$\hbox {Ni}_{4}\hbox {Ti}_{3}$$ , $$\hbox {Ni}_{3}\hbox {Ti}$$ , NiTi and NiTi $$(\hbox {B}_{19})$$ , which directly affect the shape memory, are beginning to form in the microstructure with deformation.
PubDate: 2017-05-04
DOI: 10.1007/s13369-017-2567-2

• Effect of Different Al/Ni Ratios on Structural and Acidity Properties of
Pillared Montmorillonite
• Authors: Baoru Li; Xu Wu; Zheng Li; Xia An; Xianmei Xie
Abstract: Different Al/Ni ratios of pillared montmorillonite [Al/Ni (20, 15, 10, 6, 4, 2)-PILCs] were prepared by introducing the Al/Ni cationic polymers into montmorillonite under certain conditions. The structural properties of Al/Ni-PILCs were determined by a combination of X-ray diffraction (XRD), $$\hbox {N}_{2 }$$ adsorption–desorption, $$\hbox {NH}_{3}$$ temperature programmed desorption ( $$\hbox {NH}_{3}$$ -TPD) and scanning electron microscope (SEM). Structural characterizations showed the BET surface area and the interlayer spacing of Al/Ni-PILCs decreased regularly along with the nickel content. The weak acid sites of Al/Ni-PILCs increased compared with the Na-montmorillonite, and the strong acid sites decreased. The introduction of $$\hbox {Ni}^{2+}$$ can adjust the acidity–basicity of the Al/Ni-PILC to some extent. In the reactions of the low-concentration ethanol dehydration, Al-PILC exhibited the highest catalytic activity with 93% ethanol conversion and 99% ethylene selectivity at $$500 {^{\circ }}\hbox {C}$$ .
PubDate: 2017-05-04
DOI: 10.1007/s13369-017-2558-3

• Evolution Prediction and Process Support of OSS Studies: A Systematic
Mapping
• Authors: Ghulam Rasool; Nancy Fazal
Abstract: Open source software (OSS) evolution is an important research domain, and it is continuously getting more and more attention of researchers. A large number of studies are published on different aspects of OSS evolution. Different metrics, models, processes and tools are presented for predicting the evolution of OSS studies. These studies foster researchers for contemporary and comprehensive review of literature on OSS evolution prediction. We present a systematic mapping that covers two contexts of OSS evolution studies conducted so far, i.e., OSS evolution prediction and OSS evolution process support. We selected 98 primary studies from a large dataset that includes 56 conference, 35 journal and 7 workshop papers. The major focus of this systematic mapping is to study and analyze metrics, models, methods and tools used for OSS evolution prediction and evolution process support. We identified 20 different categories of metrics used by OSS evolution studies and results show that SLOC metric is largely used. We found 13 different models applied to different areas of evolution prediction and auto-regressive integrated moving average models are largely used by researchers. Furthermore, we report 13 different approaches/methods/tools in existing literature for the evolution process support that address different aspects of evolution.
PubDate: 2017-05-04
DOI: 10.1007/s13369-017-2556-5

• Bootstrap Confidence Intervals of the Modified Process Capability Index
for Weibull distribution
Abstract: The objective of the paper is to modify the existing process capability index (PCI) for a Weibull distribution and to construct bootstrap confidence intervals (BCIs) for the newly proposed index. Three BCIs that consist of standard, percentile and bias-corrected percentile bootstrap (BCPB) confidence intervals are constructed for the newly proposed index and the existing Pearn and Chen index. The efficiency of the newly proposed index $$C_{\mathrm{GPK}}$$ is compared with Pearn and Chen index using their coverage probabilities and average widths. The coverage probabilities and average width of three BCIs were calculated using Monte Carlo simulation studies. The newly proposed index shows better performance than Pearn and Chen index. The results indicate that BCPB confidence interval was more efficient in both cases and outperform other two confidence intervals in all situations. The comparison of average width of BCPB apparently shows that the proposed index performed better in all cases. A real-life example is also provided for a practical application.
PubDate: 2017-05-03
DOI: 10.1007/s13369-017-2562-7

• Numerical Mixed Convection Heat Transfer Analysis in a Ventilated
Irregular Enclosure Crossed by Cu–Water Nanofluid
• Authors: Mahdi Benzema; Youb Khaled Benkahla; Nabila Labsi; Elisabeth Brunier; Seif-Eddine Ouyahia
Abstract: The present paper reports a numerical investigation of steady and laminar mixed convection flow within an irregular ventilated enclosure, crossed by Cu–Water nanofluid. The bottom wall is maintained at a constant and uniform temperature, whereas the top and the vertical walls are adiabatic. The inclined wall as well as the nanofluid at the entrance is kept at a lower constant temperature. The governing coupled equations are resolved by the means of the finite volume technique. The computations are performed using a homemade computer code, which was successfully validated, after comparison of our results with pervious numerical and experimental works. Empirical relations to predict the nanofluid’s effective thermal conductivity and viscosity were employed. The results are analyzed through dynamic and thermal fields with a particular attention to the Nusselt number evaluated along the active wall. The results reveal that the flow structure is more sensitive to both Richardson and Reynolds numbers variations. Moreover, heat transfer is enhanced by the increase in the nanoparticles volume fraction, Richardson and Reynolds numbers and by the decrease in the nanoparticles diameter. Useful correlations predicting the heat transfer rate as a function of nanoparticles volume fraction and diameter as well as the Richardson number are proposed.
PubDate: 2017-05-03
DOI: 10.1007/s13369-017-2563-6

• Mechanical Behaviors of Bottom Hole Assembly with Bent-Housing Positive
Displacement Motor Under Rotary Drilling
• Authors: Haosheng Liu; Tianshou Ma; Ping Chen; Xudong Wang; Xingming Wang
Abstract: Abundant drilling activities had confirmed that the fully rotary drilling can improve the rate of penetration effectively. However, the fully rotary drilling has brought some challenges for the trajectory control ability of the bottom hole assembly (BHA). One of the reasons is the effect of drill-string rotation was ignored in the existing methods, where the bent-housing positive displacement motor (PDM) was regarded as the prebending beam. According to the D’Alembert principle, the dynamical centrifugal force, generated by drill-string rotation, was equivalent to a quasi-static problem. The mechanical model of BHA with bent-housing PDM was established based on the Timoshenko beam theory. The calculated formula of bit side force (BSF) and resultant steering force (RSF) was deduced. The influences of inclination, rotational speed of drill-string, bend angle, eccentricity, stabilizer, weight on bit (WOB) and elbow position on the average BSF and RSF were investigated. The results show that the rotational speed of drill-string has a significant influence on the steering ability. The average BSF increases with the rotational speed of drill-string, while the RSF increases firstly and decreases subsequently. The controlling factor is the transverse component of drill-string gravity in a low rotational speed, while it is the centrifugal force in a high rotational speed. The BSF climbs up and then declines with WOB and rotational speed of drill-string. When the rotational speed of drill-string exceeds 100 RPM or WOB is higher than 80 kN, the BSF will decrease, resulting in a decline in angle buildup. The present method can be utilized to optimize the drilling parameters, BHA configuration and structure of bent-housing PDM.
PubDate: 2017-05-03
DOI: 10.1007/s13369-017-2564-5

• Enhancement of Defluoride Performance of the Spherical $$\hbox {FeOOH}/{\upgamma }\hbox {-Al}_{2}\hbox {O}_{3}$$ FeOOH / γ -Al 2 O 3
• Authors: Zhou Wang; Xiangqian Shen; Maoxiang Jing
Abstract: Excess fluoride in drinking water hazarded people health, so we have undertaken to develop a nanoscale $$\hbox {FeOOH}/{\upgamma }\hbox {-Al}_{2}\hbox {O}_{3}$$ absorbent to remove fluoride in drinking water. The as-prepared nanoscale $$\hbox {FeOOH}/{\upgamma }\hbox {-Al}_{2}\hbox {O}_{3}$$ absorbent was characterized by transmission electron microscopy, surface area analyzer, and X-ray diffraction. Herein, we explored the effect of pH of solution, concentration of initial fluoride, contact time, and temperature on defluoride efficiency. The results showed the composite owned to further adherence to defluoride, compared to spherical and mesoporous alumina granules. The experiment data were fit with different models and assessed by regression coefficient $$(R^{2})$$ ; the pseudo-second-order model was used to explain the adsorption process. The adsorption mechanism can be explained by a proton shifting mechanism.
PubDate: 2017-05-02
DOI: 10.1007/s13369-017-2520-4

JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327

Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs