bluuebunny/crossref_metadata_2025 huggingface dataset:
Perforation Cluster Efficiency of Cemented Plug and Perf Limited Entry Completions; Insights from Fiber Optics Diagnostics
Authors: Ugueto C. Gustavo A. , Huckabee Paul T. , Molenaar Mathieu M. , Wyker Brendan , Somanchi Kiran
Published: January 2016

It is now well established that the production from horizontal wells completed via hydraulic fracture stimulations (fracs) is highly variable along the length of the wellbore. In addition to subsurface conditions, elements of the completion design, such as fluid volume, proppant tonnage, rate, stage length, the number of perforation clusters and their spacing, influence the performance of individual stimulated intervals and wells. Information about completion efficiency can be obtained using Fiber Optic (FO) diagnostics. Distributed Temperature Sensing (DTS) and Distributed Acoustic Sensing (DAS) provide great insights into the factors controlling frac construction and performance of each perforation cluster. The integrated analysis of DAS and DTS in horizontal wells completed with multiple perforation clusters per stage indicate that, although most perforation clusters receive fluids during the stimulation, there are significant changes in efficiency during the frac stimulation process that can impact frac connectivity, conductivity and ultimately, their production. This presentation illustrates recent observations about Perforation Cluster Efficiency (PCE) using FO diagnostics and summarizes the results for many wells with Cemented Plug and Perforated completions Limited Entry design (CPnP LE).
Hydraulic Fracture Height Predictions in Laminated Shale Formations Using Finite Element Discrete Element Method
Authors: Li Han , Zou Yushi , Valko Peter P. , Ehlig-Economides Christine
Published: January 2016

Laminated structures in shale formations typically result in anisotropic elastic properties, including Young's modulus and the Poisson ratio, which highly influence hydraulic fracturing treatment execution. The lamina can confine the hydraulic fracture height growth and they sometimes act as weak interfaces for potential fracture propagation path. Hydraulic fracture geometries are highly affected by these properties. In order to make more accurate prediction of hydraulic fracture pattern, especially fracture height, these factors cannot be ignored.

We utilized a recently developed Finite Element-Discrete Element Method (FEDEM) code to simulate the complex fracture propagation in shale formations. This coupled fluid flow and geomechanics simulation can also models multi-fracture, multi well fracture propagation scenarios. For simulating fracture height growth, the bedding planes module (with corresponding mechanical anisotropy properties generation) are incorporated. Both 2D and 3D hydraulic fracture propagation studies can be performed.

Our simulation results show that without considering the mechanical anisotropy effect, the treatment design will be corrupted by the inaccurate prediction of fracture height. To be more specific, in typical mechanical anisotropic formation, fracture height is always smaller than the fracture height in mechanical isotropic formation, and the fracture tends to propagate (at least temporarily) along the bedding plane interfaces. Different bedding plane properties, including bedding plane dipping angle, permeability etc., also have strong influence on the predicted fracture height. We also consider fracture height growth in multi fracture schemes. The stress shadowing effects give rise to non-planar vertical growth and possible fracture branching. The simulations show that hydraulic fracture height growth is substantially restricted in laminated formations.

This paper provides a framework for more realistic prediction of fracture height and fracture pattern evolution in laminated shale formations exhibiting mechanical anisotropy.
Computational Fluid Dynamics Applied to Investigate Development and Optimization of Highly Conductive Channels within the Fracture Geometry
Authors: Gomaa Ahmed M. , Hudson Harold , Nelson Scott , Brannon Harold
Published: January 2016

A conventional proppant pack may lose up to 99% of its conductivity due to gel damage, fines migration, multiphase flow, and non-Darcy flow. Therefore, pillar fracturing was developed to generate highly conductive paths for hydrocarbon to flow. This paper describes experimental results and numerical models of a new method of generating stable proppant pillars The proposed treatment method depends on fingering phenomena observed when a less viscous fluid, that does not carry proppant, is injected to displace a more viscous one that carries proppant. The low-viscosity fluid will channel through the high-viscosity fluid and create isolated proppant pillars. This method promises to reduce proppant costs, pumping horsepower, and gel damage compared to conventional treatments.

Large-scale experiments (Slot tests: 2-ft height and 16-ft length) were performed to evaluate the development and stability of the created channels. In additional, a computational fluid dynamics (CFD) model was constructed using commercial CFD software, to simulate the experiment and to scale it up into full fracture dimensions. The study focused on effects of surface injection rate (1 to 120 bpm) and viscosity ratio (from 2 to 200) between the two injected fluids.

Experimental results and numerical modeling confirmed that viscous fingering phenomena can be used to create a pillar fracture with conductive and stable channels. The numerical CFD model was able to accurately predict the experimental results. Increasing the injection rate reduces the main channel width while increasing the channel branching. Full piston displacement behavior was achieved after 60% of the fracture height, when a high-viscosity fluid displaced a low-viscosity fluid and their viscosity ratio was greater than 5. By reducing the viscosity ratio between the two fluids, the created channel shape converts from cylindrical (where the beginning and end of the channel have the same width) into conical behavior (where the beginning of the channel is wider than the end). This explains why the length of the channel decreases with the viscosity ratio between the two fluids. The distance between proppant pillars tends to be reduced with increasing distance from the wellbore, or with reduced pulse stage volume, time, or rate. A full description of the created channel (distance between proppant pillars) characteristics (size, width and length) will be presented in this paper.
Dry Polyacrylamide Friction Reducer: Not Just for Slick Water
Authors: Sanders Michael , Felling Kyle , Thomson Steve , Wright Steve , Thorpe Russell
Published: January 2016

Objective/Scope: The initial goal of the project was to investigate the use of dry polyacrylamide (PAM) friction reducers as a replacement for more typical Liquid emulsion Friction Reducers (LFR) to save cost and simplify operations. In addition to using dry PAM as a slick water friction-reducing agent, the project team expanded the scope to include the idea of using it as a proppant carrier and viscosifier, a function generally done with a gel-based system. From an operating perspective, eliminating the need to switch between a slick water system and a gel-based system is attractive.

Methods, Procedures, Process: Examination of rheological properties at various temperature and salt concentrations provided background data for field trials. Friction flow loop testing provided indications of performance and compatibility. Comparative field trials of liquid vs. pre-hydrated dry friction reducers determined the benefits and best operating conditions for use of Dry Friction Reducer (DFR). Finally, a case study comparison of liquid vs. dry friction reducer is presented.

Results, Observations, Conclusions: The pre-hydrated dry friction reducers reduced fracturing pressures by more than 1,000 psi at equivalent polymer loadings, substantially lowering costs. Dry PAM friction reducers were able to convey sand concentrations of over 5 ppt (pounds per thousand gallons) and could likely conduct higher concentrations.

Novel/Additive information: The simplicity of utilizing a single polymer system to conduct slick water operations as well as increased rheology applications provides ease, convenience, increased versatility, and savings to the Exploration and Production (E&P) operator.
High Concentration Polyacrylamide-Based Friction Reducer Used as a Direct Substitute for Guar-Based Borate Crosslinked Fluid in Fracturing Operations
Authors: Motiee Monet , Johnson Maxwell , Ward Brian , Gradl Christian , McKimmy Michael , Meeheib Jeremy
Published: January 2016

Traditionally, friction reducer systems have been used to promote laminar flow in pipe to reduce friction pressure in pumping of low viscosity, slickwater-type fracture treatments. In these types of treatments, velocity is the key factor in proppant transport into the reservoir. Typical testing of these conventional friction reducer fluid systems focuses primarily on the chemical's ability to reduce treatment pressures and permit higher fluid velocities.

In an effort to reduce completions costs and improve operational efficiency while maintaining baseline well productivity, our Completions Team applied these conventional friction reducers in an unconventional way. The project used high concentrations of friction reducer (HCFR) as a direct replacement for a guar-based borate crosslinked system without modification to the standard treatment and proppant schedule. The team took steps to qualify the fluid for field implementation, including low shear rate viscosity testing, proppant settling testing, and regained conductivity testing.

Following qualification and operational planning, the team performed field trials. The data showed a reduction in footprint and overall horsepower requirements. The reduced volume and number of chemicals on location led to decreased exposure to hazardous chemicals and also simplified logistics, resulting in fewer truck movements on location. The reduction in chemicals impacted the economics of the well completion positively. The stimulation costs of the wells treated with HCFR when compared to the wells treated with the baseline fluid design showed a chemical cost reduction of approximately 22% per well.

In addition to the cost and operational efficiency benefits observed in the project, initial production data indicates that the wells are meeting or exceeding baseline productivity curves.
Improved Frac Design and Reservoir Simulation Using Strain Derived from Geomechanical Modeling - Application to the Fayetteville Shale
Authors: McKetta Steven , Vargas-Silva Sandra , Ouenes Ahmed
Published: January 2016

A workflow that uses the strain derived from geomechanical modeling of hydraulic fractures interacting with natural fractures is applied to a Fayetteville shale well. The derived strain map is used to estimate the asymmetric half lengths that are input in a frac design software able to incorporate this information. The usual symmetric bi-wing design is replaced by realistic asymmetric half lengths observed in microseismic data by adjusting the leakoff coefficient, injection rate and the proppant concentration in such a way that the asymmetric half lengths of the frac design do not exceed the lengths of those provided by the strain map. Once the half lengths and orientation from the frac design match those provided by geomechanical simulation, the propped length and other key results provided by the frac design software are used in reservoir simulation. The derived strain is correlated to stimulated permeability through two calibration constants estimated during history matching. After history matching, the resulting pressure distribution facilitates more informed selection of refrac or new well candidates, optimization of well spacing, and estimation of an accurate EUR.
Optimal Perforation Location and Limited Entry Design for Promoting Simultaneous Growth of Multiple Hydraulic Fractures
Authors: Cheng Cheng , Bunger Andrew P. , Peirce Anthony P.
Published: January 2016

The objective of achieving uniform stimulation of a reservoir through hydraulic fracturing from a horizontal well typically depends upon the ability to generate a uniform array of hydraulic fractures from multiple entry points. However getting all the hydraulic fractures in an array to grow simultaneously is a challenge. The challenge apparently arises not only due to reservoir variability, but also in a substantial part due to the stress interaction among growing hydraulic fractures. This phenomenon, referred to as a stress shadowing, inhibits the growth of inner fractures and favors the growth of outer fractures in the array. Recently, we created a new hydraulic fracture simulator which simulates the growth of an array of hydraulic fractures in 10−6–10−5 of the computation time required for fully coupled 3D simulations of multiple parallel planar hydraulic fracture growth. Using a novel energetic approach to account for the coupling among the hydraulic fractures and through judicious use of asymptotic approximate solutions, the simulation enables designs reducing the negative effects of stress shadow by balancing the interaction stresses through non-uniform perforation cluster spacings. Furthermore, so-called limited entry approaches are thought to be capable of promoting greater uniformity among simultaneously growing hydraulic fractures as long as the number and diameters of the perforations in each cluster are appropriately designed. In order to enable such optimizations and designs, we add perforation loss into to the approximate, energy-based simulator. Our results show the potential of choosing the proper perforation diameter and number to double the fracture surface area generated by a given injected fluid volume though minimizing the negative effect of interaction. The usefulness of the new simulator is demonstrated by development of example limited entry designs and optimal spacings for different numbers of entry points.
Managing Harvest Time to Control Pod Shattering in Oilseed Camelina
Authors: Sintim Henry Y. , Zheljazkov Valtcho D. , Obour Augustine K. , Garcia y Garcia Axel
Published: January 2016

Camelina (Camelina sativa L. Crantz) is an oilseed crop with the potential for dryland crop production in the Great Plains. However, pod shattering may cause significant yield losses. We determined the impact of different harvest times on camelina seed yield (SY), water use efficiency, protein and oil content, and estimated biodiesel yield. Spring (Blaine Creek) and winter (BX WG1) camelina cultivars were harvested at three different stages, corresponding to the three‐digit Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scales of 805 (early harvest; 50% ripe pods), 807 to 808 (mid‐harvest; 70–80% ripe pods), and 809 (late harvest; >90% ripe pods). In addition, different harvest methods were assessed to identify and quantify other sources of yield loss. Seed moisture contents at early, mid, and late harvests were 14.2, 9.8, and 6.8%, respectively. On average, the SY of early harvest was 9.5 and 23.6% greater than the mid‐ and late harvests, respectively. Total seed loss incurred during direct‐combine harvest was 11.7%, which was attributable to the mechanical disturbance imposed on the pods and the combine settings. Camelina seed oil content was greatest at mid‐harvest, but the estimated biodiesel yield was not significantly different between the early and mid‐harvests. In general, direct combining when 75% of camelina pods are ripe will provide a balance between SY loss and the seed protein and oil contents.
Urease and Nitrification Inhibitors Impact on Winter Wheat Fertilizer Timing, Yield, and Protein Content
Authors: Mohammed Yesuf Assen , Chen Chengci , Jensen Tom
Published: January 2016

Nitrogen fertilizer is an important input for winter wheat (Triticum aestivium L.) production. However, the losses of applied N fertilizer are economically substantial and environmentally unsafe. Therefore, improved N fertilizer management practices are needed to increase yield, enhance wheat quality, and minimize negative consequences to the environment. The objective of this experiment was to determine the impact on two N fertilizer sources, two application times, and three placement methods on grain yield, protein concentration, and N uptake of winter wheat. The experiment was conducted in Montana, in a randomized complete block design. The mean grain yield, protein concentration, and N uptake in 2010/2011 were lower than 2012/2013 due to differences in soil fertility and inter‐seasonal variations in precipitation. Treatment effects were significant in 2010/2011 (wet season) but not in 2012/2013 (dry season). In 2010/2011, urea with agrotain (urease inhibitor) and N serve (nitrification inhibitor) broadcasted in spring (UANSBS) produced the highest yield (2630 kg ha−1). This yield increase was 29% more than fall applied urea. In 2010/2011, spring broadcasting of urea, urea with agrotain, Super Urea (urea with urease and nitrification inhibitors), and UANSBS produced similar but higher yield, grain protein concentration and grain N uptake than other treatments. Therefore, considering the erratic nature of precipitation in this dry land area, spring broadcasting of urea with or without inhibitors appeared to be practical N fertilizer management practices for the region. But economic analysis is needed to justify this suggestion.
Fruska gora mountainous environments - assessing the impact of geological setting and land use on soil properties
Authors: Djordjevic Tamara , Kasanin-Grubin Milica , Gajica Gordana , Popovic Zorica , Matic Rada , Josic Ljuba , Milenkovic Milan , Lazarevic Aleksandar , Jovancicevic Branimir
Published: January 2016

On a global scale, it has been found that in the last decades the surface of
the vulnerable land and land affected by degradation is increasing and that
unsustainable land management is one of the key drivers of land degradation.
In order to assess the effect that these changes have on biodiversity and
ecosystem services, and to carry out the appropriate planning and management
actions for conserving the environment it is essential to identify and
quantify changes caused by land degradation. The aim of this study was to
determine the impact of geological setting i.e. type of bedrock, and land use
on soil physico-chemical properties in vulnerable mountainous areas of
Fruskagora. For the purpose of this study the total of 30 soil samples at
0-20 cm depth were collected at four locations on the Fruskagora Mt.
Geological setting was serpentinite and marl and land cover was forest and
meadow. Following soil properties were determined: pH, redox potential (Eh),
electrical conductivity (EC), total dissolved solids (TDS), concentrations of
available cations Ca, Mg, K, Na, contents of organic carbon (Corg) and
nitrogen (N). The correlation between the obtained parameters was tested with
two-way ANOVA and Principal Component Analyses (PCA). All of the obtained
results indicate that the soil physico-chemical properties depend on
geological setting and that rock composition has to be taken into
consideration during land management.
Milan Resetar and Stanoje Stanojevic: Fragments of cooperation on the project National Encyclopedia Serbo-Croatian-Slovene
Authors: Bozic Sofija
Published: January 2016

In the paper is published correspondence between Milan Resetar and Stanoje
Stanojevic which was kept from 1924 to 1927. The correspondence refers to
Resetar?s cooperation in National Encyclopedia Serbo-Croatian-Slovene, which
was edited by Stanojevic. Published letters contribute to more comprehensive
perception of the flow of work on the Encyclopedia and of the way of solving
the problems that occurred writing entries.
Search of amino group in the Universe: 2-aminopyridine
Authors: Sharma M.K. , Sharma M. , Sharma A.K. , Chandra S.
Published: January 2016

In search for life in the Universe, scientists are interested in
identification of molecules having amino (-NH2) group in the interstellar
space. The aminoacetonitrile (NH2CH2CN), which is precursor of the simplest
amino acid glycine (NH2CH2COOH), is identified near the galactic center. The
2-Aminopyridine (H2NC5H4N) is of interest for scientists as it has a close
association with life on the earth. Based on spectroscopic studies, we have
calculated intensities of 2-Aminopyridine lines due to transitions between
the rotational levels up to 47 cm?1 and have found a number of lines which
may help in its identification in the interstellar medium. Frequencies of
some of these transitions are found close to those detected in the envelope
of IRC +10216 that are not assigned to any of the known species.
Spatial Transferability of a Microresidential Mobility Model in the Integrated Land Use, Transportation, and Environment Modeling System
Authors: Fatmi Mahmudur Rahman , Habib Muhammad Ahsanul
Published: January 2016

This paper presents the spatial transferability analysis of a micro-behavioral model from the residential mobility component of the integrated land use, transportation, and environment (ILUTE) modeling system developed and implemented in the Greater Toronto and Hamilton Area, Ontario, Canada. The study examined whether ILUTE could be spatially transferred with the current model components to a different geographic area: Halifax, Nova Scotia, Canada. The residential mobility component within ILUTE is a continuous-time, hazard-based duration model, developed with retrospective survey data from the Residential Mobility Survey 2 in the Greater Toronto and Hamilton Area. This study developed a similar continuous-time, hazard-based duration model for the residential mobility decisions of households in Halifax on the basis of retrospective survey data from a household mobility and travel survey. The model results suggested that households in Halifax and the Greater Toronto and Hamilton Area exhibited profound differences in residential mobility decisions. Sociodemographic, dwelling, and neighborhood characteristics significantly affected residential mobility decisions in the Greater Toronto and Hamilton Area. The effects of land use and accessibility measures were noteworthy for Halifax. For instance, home-to-work distances in Halifax affected the decision to move; however, such an effect could not be confirmed in the Greater Toronto and Hamilton Area. Households' first periods of residence after household formation in a residential location were shorter in Halifax than in the Greater Toronto and Hamilton Area. It was concluded that the direct transfer of micromodels from one spatial context to another could be difficult.
Registration of ‘FL PE’, a Later‐Maturing Diploid Annual Ryegrass
Authors: Kenworthy K. E. , Reith P. E. , Prine G. M. , Blount A. R. , Quesenberry K. H.
Published: January 2016

‘FL PE’ (Reg. No. CV‐280, PI 675350) diploid annual ryegrass (Lolium multiflorum Lam.) is a synthetic cultivar selected for later maturity, excellent cold tolerance, and resistance to crown rust (caused by Puccinia coronate Corda) and gray leaf spot (caused by Pyricularia grisea Sacc.) It offers sufficient cold tolerance to be grown in the northern part of the annual ryegrass region of the United States. It also has sufficient disease resistance to be grown in the southern annual ryegrass belt. FL PE was produced from cold‐tolerant germplasm jointly produced in Scottsbluff, NE, Gainesville, FL, and Marianna, FL. The beginning seed sources for this selection program were composited in 2003 from FL/NEX2003 (new3) LRCT, FLX2003 (new3), NE/FL 2003 (new4) LRCT, NE/FLX2002 (new2) LRCT, and M/FL 2003 (new4) LRCT. Eight cycles of recurrent mass selection for crown rust resistance, gray leaf spot resistance, and mid‐late seed maturity were completed at Gainesville. FL PE showed high dry matter yields at Gainesville and was among the higher‐yielding lines at Tifton and Calhoun, GA (total of 14 location‐years data reported). Maturity ratings at Gainesville show that FL PE was among the later‐maturing lines evaluated. Late maturity can be beneficial in years with limited early summer perennial grass production; however, late maturity can also delay early summer production of these grasses, such as bermudagrass [Cynodon dactylon (L.) Pers.]. FL PE had excellent levels of resistance to crown rust disease at Gainesville.
Microstructure-based order placement in a continuous double auction agent based model
Authors: Mandeş Alexandru
Published: January 2016

This contribution proposes a novel order placement strategy which can be used for simulating continuous double auction financial markets, within an agent-based model framework. The order placement decision is given by an optimization problem which minimizes the risk adjusted execution cost, taking into consideration relevant market microstructure factors and intrinsic agent characteristics. This order submission process is more realistic than has been done previously and contributes to a higher fidelity of the intraday market dynamics. The results show that, as opposed to random submission strategies, high-frequency stylized facts such as the concave shape of the market price impact function and the power-law decaying relative price distribution of off-spread limit orders are replicated. Therefore, the resulting model can be used as a realistic test environment for high-frequency trading strategies, in the context of the current, heated debate over the impact of high-frequency trading. Not only the impact of individual trading strategies can be analyzed, but also the interdependencies and the global emergent behavior of multiple coexistent strategies. Moreover, innovative regulatory policies, which have not been tested yet under real market conditions, could be inspected.
Predominant period and amplification factor estimation with respect to geomorphology - a case study of Sylhet city corporation area, Bangladesh
Authors: Hossain Md Shakhawat , Kamal ASM Maksud , Rahman Md Zillur , Rahman Md Mostafizur , Nahar Kamrun , Woobaidullah ASM
Published: January 2016

Predominant period and amplification factor of the subsurface soils of Sylhet city corporation area have been estimated using microtremor. Their relation to the geomorphological units of the city has been determined. The estimated predominant periods of alluvial fan, back swamp, flood plain, isolated hills, level hills, piedmont plain, point bar and ridge of the city are 0.60, 0.75, 0.73, 0.23, 0.62, 0.45, 0.73 and 0.66 sec., respectively. With maximum (± 0.88) and minimum (± 0.38) standard deviation amplification factor of alluvial fan, back swamp, flood plain, isolated hills, level hills, piedmont plain, point bar and ridge are 3.1, 4.1, 4.6, 3.75, 2.22, 4.12, 4.18 and 4.42, respectively. According to amplification seismic hazard of different geomorphological units of the city has been ranked from very low to relatively high hazard zone whereas level hill falls under very low, alluvial fan under low, flood plain under relatively high and back swamp, isolated hills, piedmont plain, point bar and ridge falls under moderate hazard zone.Bangladesh J. Sci. Res. 27(1): 1-10, June-2014
Evaluation of hydrogeological conditions through vertical electrical soundings survey at Mankiganj pourashava, Manikganj, central part of Bangladesh
Authors: Woobaidullah ASM , Rahman M Moklesur , Uddin M Zohir
Published: January 2016

The Pourashava area of Manikganj, located in the central part of Bangladesh is treated as arsenic hotspot in the country as the outcome of various studies concludes that almost 80% of the domestic tube wells at this area exceed arsenic level of Bangladesh standard (50 ?g/l) for drinking water. To enhance the potable water supply in the area, 15 geoelectric soundings survey using Schlumberger configuration with spreading AB/2 = 300 meters has been executed to decipher the subsurface lithology distribution and aquifers at different depths, to determine the lateral and vertical extent of aquifer at the area. Correlation of the analyzed VES results with primary and secondary borelogs, the subsurface sequence of the area is broadly divided into two geoelectric units. Firstly, the near surface geoelectric unit of resistivity less than 20.0 ?-m represents the top soil composed of silty clay to clay. The thickness of this layer varies from 1 meter to 5 meters. The second geoelectric unit represents the sand layer and is characterized by a resistivity range of 21.0 to 190.0 ?-m. This unit encompasses the very fine sand with variable thickness of 2 to 248m while resistivity is from 21.0 to 30.0 ?-m, very fine to fine sand having thickness from 174-280m and geoelectric value ranges from 31.0 to 40.0 ?-m, fine sand with resistivity from 44.0 to 50.0 ?-m, fine to medium sand having resistivity from 51.0 to 70.0 ?-m, medium sand and medium to coarse sand with resistivity value 75.0 to 110.0 ?-m, and 140.0 to 190.0 ?-m, respectively. The ultimate thickness of this unit could not be determined due to limited spread of survey but at least continues to a depth of 300 m. In the context of groundwater storage, the second geoelectric unit acts as the regional aquifer and is used for groundwater development in the Pourashava area for water supply.Bangladesh J. Sci. Res. 27(2): 109-120, December-2014
EM algorithm for longitudinal data with non-ignorable missing values: An application to health data
Authors: Taisir Radia , Islam M Ataharul
Published: January 2016

Longitudinal studies involves repeated observations over time on the same experimental units and missingness may occur in non-ignorable fashion. For such longitudinal missing data, a Markov model may be used to model the binary response along with a suitable non-response model for the missing portion of the data. It is of the primary interest to estimate the effects of covariates on the binary response. Similar model for such incomplete longitudinal data exists where estimation of the regression parameters are obtained using likelihood method by summing over all possible values of the missing responses. In this paper, we propose an expectation-maximization (EM) algorithm technique for the estimation of the regression parameters which is computationally simple and produces similar efficient estimates as compared to the existing complex method of estimation. A comparison of the existing and the proposed estimation methods has been made by analyzing the Health and Retirement Survey (HRS) data of United States.Bangladesh J. Sci. Res. 27(2): 133-142, December-2014
Effects of viscous dissipation and thermal radiation on MHD forced convective heat and mass transfer flow of non-Newtonian power law fluid with heat generation
Authors: Samad MA , Podder C
Published: January 2016

An analysis is carried out to investigate the effects of forced convection heat and mass transfer of an electrically conducting, non-Newtonian power-law fluid past a stretching sheet. This has been done under the simultaneous action of suction, radiation, uniform transverse magnetic field, heat generation and viscous dissipation. The stretching sheet is assumed to continuously moving with a power-law velocity and maintaining a uniform surface heat flux. The governing nonlinear partial differential equations are transformed into a system of nonlinear ordinary differential equations using appropriate similarity transfor-mations. The resulting dimensionless equations are solved numerically using sixth order Runge-Kutta integration scheme with Nachtsheim-Swigert shooting iterative technique. A systematical study of numerical results for the non-dimensional velocity, temperature and concentration profiles are presented graphically. Due to physical and engineering interest, the viscous drag or local Skin-friction coefficient, heat transfer rate or local Nusselt number and mass transfer rate or local Sherwood number are represented in tabular form to illustrate the details of flow characteristics and their dependence on all physically important parameters of different non-Newtonian fluids. A comparison of the present study and previously published paper has also been shown in tabular form.Bangladesh J. Sci. Res. 27(2): 187-200, December-2014
Safe drinking water: effect of granular activated carbon bed characteristics on iron removal from water
Authors: Rasul Md Golam , Ahmed Imtiaz , Hossain Md Iqbal
Published: January 2016

Tuning the characteristics of granular activated carbon bed (GAC-bed) in household water-filters would be a technique to maintain iron at the required-level in drinking water. In the present study the individual effects of the depth of GAC-bed and the size and porosity of GAC particles on the iron removing capacity are investigated experimentally. A spectrophotometer is used to measure iron-content in water. It is observed that iron removing capacity increases monotonically with the increase in bed-depth regardless of the size of GAC particles. It is also observed that the iron removing capacity decreases drastically with the increase in the size of GAC particles for any fixed bed-depth. Finally the porosity of GAC particles is found to affect the iron removing capacity. The higher the GAC porosity the higher is the iron removing capacity over the considered porosity-range. It is believed that the observations of present study would be useful in adjusting GAC-bed characteristics at the time of designing household water-filters to maintain iron at the required-level.

Chemical Engineering Research Bulletin 18(2015) 1-5
Agro-industrial development and sustainability in Bangladesh-A study
Authors: Latif MA , Rahman MH , Ehasan MA
Published: January 2016

A study was conducted to know the current state of development sustainability of the agroindustrial sector in terms of its product diversity, export volume, export value, destination of the product by region and country. A structured questionnaire was prepared to do the random sampling survey and focused group discussion also held with the relevant stakeholder in agro-industrial sphere. The study revealed that in terms of value, the highest exported agro processed product is spices 21.46 million US$ (25%) and in terms of weight, the highest exported agro processed product is drinks (26735 ton). It is investigated that 81% of Bangladesh agro processed product goes to Asian market which value is US$ 70.13 million. In terms of export value, the major destination of Bangladesh agro-processed product is Kingdom of Saudi Arabia(KSA) which amount is 20.2 million US$. In terms of export in weight, the major destination of Bangladesh agro-processed product is India (24372.88 metric ton).Int. J. Agril. Res. Innov. & Tech. 5 (2): 37-43, December, 2015
Impact of agribusiness labour on the child education in Cameroon
Authors: Gildas Tiwang N , Manu Ibrahim N
Published: January 2016

This paper aimed to assess the involvement of child labour in agribusinesses as well as the schooling pattern of children involved in these agribusinesses in Cameroon. For this study, some descriptive statistics and cross tabulations were computed using SPSS.20 and stata 13 software packages. The population of this study was made up of 51,190 individuals of both sexes that were concerned by the third Cameroon National Household Survey. The sample drawn from this population was constituted of individuals of age 5-17 years old, making a total of 17,550 children. The main results of this study revealed that agribusiness child labour was present everywhere in Cameroon and by both boys and girls. Children of all ages of the sample were concerned by the phenomenon and their level of education was essentially the primary. The impact of agribusiness child labour on education was positive because it helped the working and schooling children to provide means to finance their education and other needs. On the other hand, it has a negative impact on education because some children went for these jobs and finally stayed there and did not return back to school.Int. J. Agril. Res. Innov. & Tech. 5 (2): 58-63, December, 2015
Role of Exogenous Carbohydrate and Amino Acid Sources on Biomass and Colchicine Production in Nontransformed Root Cultures of Gloriosa superba
Authors: Ghosh Seemanti , Ghosh Biswajit , Jha Sumita
Published: January 2016

Elicitation strategies were studied for yield enhancement of colchicine, produced by root cultures of Gloriosa superba. Adventitious root cultures were established and grown in media containing 3 mg/l NAA and 1 mg/l BA. Root cultures showed variations in biomass as well as colchicine production in the presence of different exogenous carbohydrates and amino acid. Among the different sources of carbohydrates used - fructose, sucrose and dextrose gave a substantially higher biomass yield than the control. Maximum biomass was obtained in the presence of fructose. Root cultures growing in mannitol supplemented medium resulted in maximum accumulation of colchicine (0.32%). Among the amino acids, serine and phenylalanine significantly enhanced colchicine accumulation in root cultures. 0.02 mM glutamine supplemented media showed maximum (ten-fold) increase of root biomass.Plant Tissue Cult. & Biotech. 25(2): 247-256, 2015 (December)
A New Type of Hydraulic Muscle
Authors: Drimer Nitai , Mendelson Jonathan , Peleg Amitai
Published: January 2016

This paper presents the invention and development of a new fundamental type of hydraulic actuator, aimed at delivering better actuation efficiency. This actuator is a flexible tube, composed of two different materials, which deflects while applying inner pressure. This concept is simple to produce, and allows adaptation of the deflected shape by the design parameters (radius, wall thickness, geometry, etc.). Among other applications, it is mostly suitable for the activation of fins of nature-like marine robots. Theoretical formulation, production of prototypes and actuation experiments are presented, as well as material hysteresis research and an application example.
Contribution of Nitrogen Uptake and Retranslocation during Reproductive Growth to the Nitrogen Efficiency of Winter Oilseed-Rape Cultivars (Brassica napus L.) Differing in Leaf Senescence
Authors: Koeslin-Findeklee Fabian , Horst Walter
Published: January 2016

Genotypic variation in N efficiency defined as high grain yield under limited nitrogen (N) supply of winter oilseed-rape line-cultivars has been predominantly attributed to N uptake efficiency (NUPT) through maintained N uptake during reproductive growth related to functional stay-green. For investigating the role of stay-green, N retranslocation and N uptake during the reproductive phase for grain yield formation, two line cultivars differing in N starvation-induced leaf senescence were grown in a field experiment without mineral N (N0) and with 160 kg N·ha−1 (N160). Through frequent harvests from full flowering until maturity N uptake, N utilization and apparent N remobilization from vegetative plant parts to the pods could be calculated. NUPT proved being more important than N utilization efficiency (NUE) for grain yield formation under N-limiting (N0) conditions. For cultivar differences in N efficiency, particularly N uptake during flowering (NUPT) and biomass allocation efficiency (HI) to the grains, were decisive. Both crop traits were related to delayed senescence of the older leaves. Remobilization of N particularly from stems and leaves was more important for pod N accumulation than N uptake after full flowering. Pod walls (high N concentrations) and stems (high biomass) mainly contributed to the crop-residue N at maturity. Decreasing the crop-inherent high N budget surplus of winter oilseed-rape requires increasing the low N remobilization efficiency particularly of pod-wall N to the grains. Addressing this conclusion, multi-year and -location field experiments with an extended range of cultivars including hybrids are desirable.
Autoantibodies in SLE: Specificities, Isotypes and Receptors
Authors: Dema Barbara , Charles Nicolas
Published: January 2016

Systemic Lupus Erythematosus (SLE) is characterized by a wide spectrum of auto-antibodies which recognize several cellular components. The production of these self-reactive antibodies fluctuates during the course of the disease and the involvement of different antibody-secreting cell populations are considered highly relevant for the disease pathogenesis. These cells are developed and stimulated through different ways leading to the secretion of a variety of isotypes, affinities and idiotypes. Each of them has a particular mechanism of action binding to a specific antigen and recognized by distinct receptors. The effector responses triggered lead to a chronic tissue inflammation. DsDNA autoantibodies are the most studied as well as the first in being characterized for its pathogenic role in Lupus nephritis. However, others are of growing interest since they have been associated with other organ-specific damage, such as anti-NMDAR antibodies in neuropsychiatric clinical manifestations or anti-β2GP1 antibodies in vascular symptomatology. In this review, we describe the different auto-antibodies reported to be involved in SLE. How autoantibody isotypes and affinity-binding to their antigen might result in different pathogenic responses is also discussed.
Coordinated Volt/Var Control in Distribution Systems with Distributed Generations Based on Joint Active and Reactive Powers Dispatch
Authors: Samimi Abouzar , Kazemi Ahad
Published: January 2016

One of the most significant control schemes in optimal operation of distribution networks is Volt/Var control (VVC). Owing to the radial structure of distribution systems and distribution lines with a small X/R ratio, the active power scheduling affects the VVC issue. A Distribution System Operator (DSO) procures its active and reactive power requirements from Distributed Generations (DGs) along with the wholesale electricity market. This paper proposes a new operational scheduling method based on a joint day-ahead active/reactive power market at the distribution level. To this end, based on the capability curve, a generic reactive power cost model for DGs is developed. The joint active/reactive power dispatch model presented in this paper motivates DGs to actively participate not only in the energy markets, but also in the VVC scheme through a competitive market. The proposed method which will be performed in an offline manner aims to optimally determine (i) the scheduled active and reactive power values of generation units; (ii) reactive power values of switched capacitor banks; and (iii) tap positions of transformers for the next day. The joint active/reactive power dispatch model for daily VVC is modeled in GAMS and solved with the DICOPT solver. Finally, the plausibility of the proposed scheduling framework is examined on a typical 22-bus distribution test network over a 24-h period.
A Notched Long-Period Fiber Grating Magnetic Field Sensor Based on Nanoparticle Magnetic Fluid
Authors: Wang Sheng-Feng , Chiang Chia-Chin
Published: January 2016

In this paper, we propose using an inductively coupled plasma (ICP) etching technique to fabricate a notched long-period fiber grating (NLPFG) for magnetic sensing application. An optical fiber magnetic field sensor based on NLPFG filled with nanoparticle magnetic fluid is proposed and demonstrated. The magnetic fluid nanoparticles were attached on the grating structure section and used as a magneto-optical sensing layer to measure magnetic flux density. The external applied magnetic flux density ranged from 0 to 27.74 mT. As the magnetic flux density was increased, the spectra of the NLPFG were changed. The resonant wavelength of the attenuation band did not shift obviously, but the transmission loss of the resonant dip was increased by 3.48 dB from −19.41 dB to −15.93 dB. The experimental results indicated that the sensitivity of the sensor is approximately 0.125 dB/mT.
Multi-Scale Observations of Atmosphere Environment and Aerosol Properties over North China during APEC Meeting Periods
Authors: Wei Xi , Gu Xingfa , Chen Hao , Cheng Tianhai , Wang Ying , Guo Hong , Bao Fangwen , Xiang Kunsheng
Published: January 2016

This paper reveals a study on air pollution process over North China, applying remote sensing technology, using satellite observation and in situ measurements during the twenty-first Asia-Pacific Economic Cooperation (APEC) meeting, which was held in Beijing between 6 and 12 November when the clear weather was called “APEC-Blue”. In the meantime, pollutants concentrations including PM2.5 and PM10 in Beijing were lower than 100 μg/m3 owing to the effective government measures and policies, as well as meteorological conditions. High aerosol loading (AOD > 1) was observed over south of Beijing and vertical observations showed that the pollutants were prominent near the land surface. Different from the meeting period, high pollutants concentrations with explosive growth (the values of PM2.5 and PM10 peaking at 291 μg/m3 and 360 μg/m3 respectively) appeared over Beijing after the meeting period, accompanied by strong temperature inversion and high Relative Humidity (RH) values. The pollution particles transferred from Beijing area to south part of North China. Otherwise, fine-mode particles with strong absorption characteristic (UVAI > 1.5, AOD > 1) covered the Beijing sky in the meantime, indicating the existence of black carbon aerosols.
Comprehensive Evaluation of High-Resolution Satellite-Based Precipitation Products over China
Authors: Guo Hao , Chen Sheng , Bao Anming , Hu Junjun , Yang Banghui , Stepanian Phillip
Published: January 2016

Characterizing the errors in satellite-based precipitation estimation products is crucial for understanding their effects in hydrological applications. Six precipitation products derived from three algorithms are comprehensively evaluated against gauge data over mainland China from December 2006 to November 2010. These products include three satellite-only estimates: the Global Satellite Mapping of Precipitation Microwave-IR Combined Product (GSMaP_MVK), the Climate Prediction Center (CPC) MORPHing (CMORPH), and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN), as well as their gauge-corrected counterparts: the GSMaP Gauge-calibrated Product (GSMaP_Gauge), bias-corrected CMORPH (CMORPH_CRT), and PERSIANN Climate Data Record (PERSIANN-CDR). Overall, the bias-correction procedures largely reduce various errors for the three groups of satellite-based precipitation products. GSMaP_Gauge produces better fractional coverage with the highest correlation (0.95) and the lowest RMSE (0.53 mm/day) but also high RB (15.77%). In general, CMORPH_CRT amounts are closer to the gauge reference. CMORPH shows better performance than GSMaP_MVK and PERSIANN with the highest CC (0.82) and the lowest RMSE (0.93 mm/day), but also presents a relatively high RB (−19.60%). In winter, all six satellite precipitation estimates have comparatively poor capability, with the IR-based PERSIANN_CDR exhibiting the closest performance to the gauge reference. Both satellite-only and gauge-corrected satellite products show poor capability in detecting occurrence of precipitation with a low POD (<50%) and CSI (<35%) and a high FAR (>40%).
Cancer Stem Cells and Their Interaction with the Tumor Microenvironment in Neuroblastoma
Authors: Garner Evan , Beierle Elizabeth
Published: January 2016

Neuroblastoma, a solid tumor arising from neural crest cells, accounts for over 15% of all pediatric cancer deaths. The interaction of neuroblastoma cancer-initiating cells with their microenvironment likely plays an integral role in the maintenance of resistant disease and tumor relapse. In this review, we discuss the interaction between neuroblastoma cancer-initiating cells and the elements of the tumor microenvironment and how these interactions may provide novel therapeutic targets for this difficult to treat disease.