Analytical Production Modeling for Hydraulically Fractured Gas Reservoirs

This article presents a complete analytical method to efficiently generate gas production profiles from hydraulically fractured reservoirs. Equations for production rates are first developed incorporating fracture parameters in the diffusivity-based drawdown solutions for transient as well as pseudo steady-state flow conditions. Some important considerations for modeling the key propped-fracture parameter—dimensionless fracture conductivity—are detailed for realistic production prediction. A time-step algorithm is then discussed to apply the rate equations to generate production profiles over a period of time. Analytical equations are presented to update declining reservoir pressure and resulting rock and gas properties in every time-step as functions of cumulative gas productions. Finally, a simple new equation is developed through a series of parametric applications of the two rate equations, to determine the time to switch from the transient rate equation to the pseudo steady-state equation, particularly in low-permeability reservoirs. To establish confidence in the predictability of the model, results are verified by a numerical reservoir simulator. Thus, the model is a high potential for efficient repetitive computation in early-stage design optimization of hydraulic fracture treatments for gas reservoirs.     

Immobilization of lactobionic acid on the surface of cadmium sulfide nanoparticles and their interaction with hepatocytes

In the current study, β-galactose-carrying lactobionic acid (LA) was conjugated on the surface of mercaptoacetic acid-coated cadmium sulfide nanoparticles (CSNPs) to ensure specific recognition of liver cells (hepatocytes) and to enhance biocompatibility. Maltotrionic acid-coated CSNPs (MCSNPs) were also prepared for use as a control. The results showed that LA-immobilized CSNPs (LCSNPs) were selectively and rapidly internalized into hepatocytes and emitted more intense fluorescence images as well as demonstrated increased biocompatible behavior in vitro than those of CSNPs and MCSNPs. Furthermore, the uptake amount of LCSNPs into hepatocytes was higher than that of CSNPs and MCSNPs. All these results indicate that LCSNPs may find ever-growing applications in biological labels and detection or contrast agents in life science and medical diagnostics.     

Family of estimators of mean,ratio and product of a finite population using random nonresponse

In this paper a family of estimators for estimating mean, ratio and product of two means of a finite population are suggested and studied under the two different situations of random non-response considered by Tracy and Osahan (1994, Statistica 54(2):163–168), Singh and Joarder (1998, Metrika 47:241–249) and Singh et al. (2000, Statistica 60(1):39–44). Asymptotic expressions of biases and mean squared errors of the proposed families are derived. Optimum conditions are obtained under which the proposed families of estimators have the minimum mean squared error (MSE). Furthermore, the optimum values, depending upon population parameters, when replaced by sample values, yield the estimators having the minimum MSE of the optimum estimators. The estimators for MSEs of the suggested families are also given.      

Synthesis,thermal, and photo alignment behavior of polyethylene imines having nitro substituent azobenzene side chain group

Polyethylene imines having nitro substituent azobenzene side chain group with different methylene spacer groups (PEImN) were successfully synthesized and characterized by differential scanning calorimetry, polarized optical microscopic, and X‐ray diffraction analysis. All synthesized polyethylene imines showed liquid crystalline properties and the glass transition temperature (Tg) of PEImN decreased as the number of methylene spacers increased. Melting temperatures (Tm) of synthesized PEImN showed an odd‐even effect. Photochemical, thermo‐optical, as well as photo alignment behavior of PEImN were investigated and out‐of‐plane orientational behavior of polymeric films was dependent on number of methylene spacers and polyethylene imines having higher number of methylene spacers (six or more) showed high order parameter values that revealed the well pronounced tendency for the development of out‐of‐plane order from random state on annealing. And the molecular orientation of PEImN between random and out‐of‐plane structures has been achieved by the combination of thermal and photochemical processes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A model for water sharing in the Ganges River Basin

This study investigates water resources sharing and in particular the impact of the Farakka Barrage in the Ganges River Basin management which has led to conflict between the Ganges states since 1951. A deadlock prevailed between Bangladesh and India during the dry seasons. The 1996 water sharing treaty adopted and the results suggest that availability of flows is crucial during the period 1 March to 31 May. Moreover, the average flow availability at Farakka dam has been gradually declining during the period 1997 to 2007. For 2005 and 2006, it was found that the average flow availability declined by 12 and 25%, respectively. A Stackelberg leader–follower model is described for optimal water allocation in the Ganges River Basin between Bangladesh and India both with and without additional water transfers from Nepal. It is recommended that a market‐based water transfer arrangement from Nepal is implemented for both Bangladesh and India.     

Reduced cytotoxicity of insulin-immobilized CdS quantum dots using PEG as a spacer

Cytotoxicity is a severe problem for cadmium sulfide nanoparticles (CSNPs) in biological systems. In this study, mercaptoacetic acid-coated CSNPs, typical semiconductor Q-dots, were synthesized in aqueous medium by the arrested precipitation method. Then, amino-terminated polyethylene glycol (PEG) was conjugated to the surface of CSNPs (PCSNPs) in order to introduce amino groups to the surface. Finally, insulin was immobilized on the surface of PCSNPs (ICSNPs) to reduce cytotoxicity as well as to enhance cell compatibility. The presence of insulin on the surface of ICSNPs was confirmed by observing infrared absorptions of amide I and II. The mean diameter of ICSNPs as determined by dynamic light scattering was about 38 nm. Human fibroblasts were cultured in the absence and presence of cadmium sulfide nanoparticles to evaluate cytotoxicity and cell compatibility. The results showed that the cytotoxicity of insulin-immobilized cadmium sulfide nanoparticles was significantly suppressed by usage of PEG as a spacer. In addition, cell proliferation was highly facilitated by the addition of ICSNPs. The ICSNPs used in this study will be potentials to be used in bio-imaging applications.     

Development of a neural network based integrated control system of 120 ton/h capacity boiler

An integrated control system based on artificial neural network (ANN) is presented in this paper to control a 120 ton/h capacity boiler of the Zia Fertilizer Company Limited (ZFCL), Ashuganj, Bangladesh. The process inverse dynamic modelling technique is applied to design the proposed controller. A multilayer feed-forward neural network is trained to identify the unknown inverse dynamic model of the boiler plant by a well known learning algorithm called backpropagation. The training data were collected from the history file of ZFCL. A new software controller is then developed for integrated control system of the ZFCL boiler using the weights of the trained network. Both the training mode and running mode of the developed controller are presented in this paper. The controller output is also converted into electrical signal using pulse width control technique. The generated signal is used for on-line regulation of the control valve through the parallel port of the computer. The developed controller is tested by using the boiler input–output data that are not used during the training. The output response and performance of the developed controller is compared with those of the existing PID controller of the plant.     

Structuration and Destructuration Behavior of Cement-Treated Singapore Marine Clay

This paper examines the structuration and destructuration characteristics of cement-treated Singapore marine clay and their relation to the observed microstructural behavior. The pozzolanic reaction is found to be very significant up to curing periods of 1?year, and thus the unconfined compressive strength increases notably leading to the formation of more structured treated clay. Due to the effect of structuration (existing of cementation bond), the yield stress increases resulting in an expansion of the yield surface and failure envelope under compression and shearing. The microstructural observation of treated clay structure at various stress levels from one-dimensional consolidation shows that destructuration (breaking of cementation bond) is progressive; the largest intercluster voids being the first affected. As the consolidation proceeds, both inter and intracluster voids are affected. Consolidated undrained triaxial results reveal that complete destructuration only takes place on the shear plane at which the clay–cement cluster crushes.