GRAPHICAL SOLUTION OF MULTISTAGE FLUIDIZED BED HEAT EXCHANGER

The design of multistage fluidized beds for heat exchange necessitates the solution of the mass and energy balance equations combined with the equilibrium relations for each stage. This paper presents a novel way of applying well known methodology to a different technology, one where it has not been widely applied.

In the present work a McCabe-Thiele type of graphical approach is presented for both counter-current and cross-current contacting multiple fluidized beds. The necessary equations for a multistage calciner are developed and the application of the proposed method is demonstrated. Generalized fluidized bed efficiency for counter-current and cross-current multiple fluidized bed is presented.     

Correlating the 3D melt electrospun polycaprolactone fiber diameter and process parameters using neural networks

In the present work, we developed an artificial neural networks (ANN) model to predict and analyze the polycaprolactone fiber diameter as a function of 3D melt electrospinning process parameters. A total of 35 datasets having various combinations of electrospinning writing process variables (collector speed, tip to nozzle distance, applied pressure, and voltage) and resultant fiber diameter were considered for model development. The designed stand-alone ANN software extracts relationships between the process variables and fiber diameter in a 3D melt electrospinning system. The developed model could predict the fiber diameter with reasonable accuracy for both train (28) and test (7) datasets. The relative index of importance revealed the significance of process variables on the fiber diameter. Virtual melt spinning system with the mean values of the process variables identifies the quantitative relationship between the fiber diameter and process variables.     

The determination of the enthalpy of formation and the enthalpy increment of Cd0.5Te0.5 by Calvet calorimetry

The enthalpy of formation of Cd_0.5Te_0.5(s) has been determined using a Calvet calorimeter at 785 K by direct reaction calorimetry. The heat changes were measured for the additions of Cd(s) or Te(s) from 298 K to a reaction crucible containing the other liquid metal at 785 K. Measurements were also carried out to determine the enthalpy changes due to the direct reaction of the Te(l) and Cd(l) at 785 K. The enthalpies of formation of Cd_0.5Te_0.5 calculated from the two sets of experiments were in agreement. The H_T°---H₂₉₈° values of the Cd_0.5Te_0.5 compound have also been determined in the temperature range 406–826 K by the drop method. Using ΔH_fm° at 785 K and H_T---H₂₉₈° values of Cd_0.5Te_0.5, ΔH_fm° at 298 K was determined to be −(50.349±0.510) kJ mol⁻¹.     

Effects of porous carbon on sintered Al-Si-Mg matrix composites

The influence of microporous particulate carbon char on the mechanical, thermal, and tribological properties of wear-resistant Al-13.5Si-2.5Mg alloy composites was studied. Large increases in surface area due to the formation of micropores in coconut shell chars were achieved by high-temperature activation under CO₂ gas flow. Activated char particles at 0.02 V _f were used to reinforce the alloy. The composites were fabricated via a double-compaction reaction sintering technique under vacuum at a compaction pressure of 250 MPa and sintering temperature of 600 °C. At more than 35% burn-off of the carbon chars at the temperature of activation, 915 °C, the total surface area remained virtually unaffected. The ultimate tensile strength and hardness decreased by 23% and 6 %, respectively; with increasing surface area of the reinforcement from 123 to 821 m²g⁻¹. The yield strength and the percentage of elongation decreased by a factor of 2 and 5, respectively. No significant change in sliding wear rate was observed but the coefficient of friction increased by 13 % (0.61 to 0.69). The coefficient of linear thermal expansion was reduced by 16 % (11.7 × 10⁻⁶ to 9.8 × 10⁻⁶ °C⁻¹), and remained unaffected at more than 35 % burn-off. Energy-dispersive spectrometry of the particles of the activated chars showed that oxides of potassium and copper coated the open surfaces. Failure at the matrix-char interface was observed, and this was attributed to localized presence of oxides at the interfaces as identified by electron probe microanalysis. Poor wetting of the oxides by magnesium at the sintering conditions resulted in formation of weak matrix-char interface bonds. J.U. Ejiofor, formerly of the Department of Metallurgical and Materials Engineering, The University of Alabama     

Effect of polyaluminium chloride on phosphorus removal in constructed wetlands treated with swine wastewater

Total phosphorus (TP) removal in aged constructed wetlands poses a challenge, especially when treated with swine wastewater with high concentrations of phosphorus (P). Our earlier studies with anaerobic lagoon swine wastewater treatment in constructed wetlands showed a decline in P removal (45-22%) with increased years of operation. These particular wetlands have been treated with swine wastewater every year since the first application in 1997. Preliminary lab-scale studies were conducted to evaluate the efficiency of polyaluminium chloride (PAC) in the removal of phosphate-P (PO4-P) from swine wastewater. The experimental objective was to increase the phosphorus treatment efficiency in constructed wetland by adding PAC as a precipitating agent. PAC was added by continuous injection to each wetland system at a rate of 3 L day(-1) (1:5 dilution of concentrated PAC). Swine wastewater was added from an anaerobic lagoon to four constructed wetland cells (11m wide x 40m long) at TP loads of 5.4-6.1 kg ha(-1) day(-1) in two experimental periods, September to November of 2008 and 2009. Treatment efficiency of two wetland systems: marsh-pond-marsh (M-P-M) and continuous marsh (CM) was compared. The wetlands were planted with cattails (Typha latifolia L.) and bulrushes (Scirpus americanus). In 2008, PAC treatment showed an increase of 27.5 and 40.8% of TP removal over control in M-P-M and CM respectively. Similar trend was also observed in the following year. PAC as a flocculant and precipitating agent showed potential to enhance TP removal in constructed wetlands treated with swine wastewater.     

Semiconcurrent Online Testing of Transition Faults through Output Response Comparison of Identical Circuits

We describe a method for online testing of delay faults based on the comparison of output responses of identical circuits. The method allows one of the circuits to participate in useful computations during the testing process, while the other circuit must be idle. We refer to this method as semiconcurrent online testing. While unknown input vectors are applied to the circuit that participates in useful computations, the proposed method applies modified vectors to the idle circuit. In this way, different conditions are created for the detection of delay faults, allowing identical delay faults that affect both circuits to be detected. In designing the modified vectors, we ensure that the expected fault-free responses of the two circuits are identical. We also ensure that the hardware for modifying the vectors applied to the idle circuit will be easy to implement on-chip.     

Solubility and thermodynamic properties of Y2O3 in LiF-YF3 melts

A systematic investigation was undertaken to measure the solubility of Y₂O₃ in several LiF-YF₂ melts, with the YF₃ composition ranging from 20 to 50 mole pct, in the temperature range of 998 to 1273 K. Experimental results showed that the solubility of Y₂O₄ in the melts increased with increase in temperature and also with increased YF₃ content. The activity of Y₂O₃ was calculated using the free energy of fusion of Y₂O₃, . The was deduced from the values of enthalpy, heat of fusion, and melting point of Y₂O₃. From the known values of activity, the activity coefficients of Y₂O₃ as a function of temperature and melt composition were calculated. Considering the ionic nature of the melt, activity coefficients were also calculated using Temkin’s ideal mixing and electrically equivalent fraction methods. The thermodynamic data, such as integral molar enthalpy, entropy, and free energy of formation, were calculated as a function of composition and temperature. The calculated thermodynamic data showed that the melt exhibited a negative deviation from ideal conditions.     

Circular Fractal Antenna Design with Inscribed Square for Ultra Wide Band Applications

Journal of Communications Technology and Electronics - In this article, an ultra-wide band circular fractal antenna inscribed with square is presented. The prototype of the antenna is fabricated on...     

Image super resolution model enabled by wavelet lifting with optimized deep convolutional neural network

This paper plans to develop an intelligent super resolution model with the linkage of Wavelet lifting scheme and Deep learning algorithm. Before initiating the resolution procedure, the entire HR images are converted into Low Resolution (LR) images using bicubic interpolation-based downsampling and upsampling. Further, the Wavelet lifting scheme helps to generate the four subbands of each image like LR wavelet Sub-Bands for LR images, and High Resolution (HR) wavelet Sub-Bands for HR images. The residual image is generated by taking the difference between the LR wavelet Sub-Bands and HR wavelet Sub-Bands images. The proposed model involves two main phases: Training phase and Testing. The training phase trains the residual image of all images by Deep Convolutional Neural Network with LR wavelet Sub-Bands as input and residual image as target. On the other hand, in testing phase, the LR wavelet Sub-Bands query image is subjected to Deep Convolutional Neural Network, which outputs the concerned residual image. This generated residual image is summed with LR wavelet Sub-Bands image, followed by inverse wavelet lifting scheme to obtain the final super resolution image. The main contribution of this paper is to improve the conventional Deep Convolutional Neural Network by optimizing the number of hidden layer, and hidden neurons using modified Whale Optimization Algorithm called Average Fitness Enabled Whale Optimization Algorithm by considering the objective of maximizing the Peak Signal-to-Noise Ratio. Finally, the proposed method achieves an improved quality of the results which is comparable the existing models.