Effect of additives on the properties and performance of cellulose acetate derivative membranes in the separation of isopropanol/water mixtures

In this work, various cellulose acetate (CA) membranes for pervaporation were prepared by the incorporation of different additives, i.e. polyethylene glycol-600 (PEG-600), propylene glycol (PG), and ethylene glycol (EG) to enhance the separation of isopropanol (IPA)/water mixtures. These membranes were characterized by FTIR, DSC, TGA, SEM and UTM. Each additive was responsible for its characteristic effect on the membrane morphology, mechanical strength, permeation flux and separation factor. The SEM micrograph showed that the additives were evenly dispersed in the membrane matrix with the formation of dense membranes. The UTM tests for the membrane reveled that both the Young's Modulus and tensile strength increased with the increase in additive contents. TGA studies for the CA/PEG blend membrane exhibited the highest thermal stability as compared to the CA/PG and CA/EG blends. For each of these synthesized membranes, the separation factor decreased while the permeation flux increased with the increase in additive contents, while the CA/PG membrane with 20 wt.% additive content showed highest permeation flux of 452.27 g/m²h.     

Revised estimates for continuous shoreline fumigation: a PDF approach

A probability density function (PDF) fumigation model is presented here to study the dispersion of air pollutants emitted from a tall stack on the shoreline. This work considers dispersion of the pollutants in the stable layer and within the thermal internal boundary layer (TIBL) proceeds independently. The growth of TIBL is considered parabolic with distance inland. Turbulence is taken as homogeneous and stationary. Dispersion of particles (contaminant) in lateral and vertical directions is assumed independent of each other. This assumption allows us to consider the position of particles in both directions as independent random variables. The lateral dispersion distribution within the TIBL is considered as Gaussian and independent of height. A skewed bi-Gaussian vertical velocity PDF is used to account for the physics of dispersion due to different characteristics of updrafts and downdrafts within the TIBL. We have used Weil (J.C. Weil, A diagnosis of the asymmetry in top-down and bottom-up diffusion using a Lagrangian stochastic model, J. Atmos. Sci., 47 (1990) 501-515) solutions to find out the parameters of this PDF. Incorporating finite Lagrangian integral time scale for the vertical velocity component, it is observed that it reduces the vertical dispersion in the beginning and moves the point of maximum concentration further downwind. Due to little dispersion in the beginning, there is more plume to be dispersed causing higher concentrations at large distances. The model has considered Weil and Brower's (J.C. Weil, P.R. Brower, Estimating convective boundary layer parameters for diffusion applications, Maryland Power Plant Siting Program Rep. PPSP-MP-48, Department of Natural Resources, Annapolis, MD, 1985, 37 pp.) convective limit to analyze dispersion characteristics within TIBL. The revised model discussed here is evaluated with the data available from the Nanticoke field experiment on fumigation conducted in summer of 1978 in Ontario, Canada. The results of revised model are in good agreement with the observed data.     

Simple and spectrally-efficient design of high capacity hybrid WDM/TDM-PON with improved receiver sensitivity

A simple design of hybrid wavelength division multiplexed/time division multiplexed passive optical network （WDM/ TDM-PON） is demonstrated for the high capacity next generation access （NGA） network, having advantages of both WDM and TDM based PON techniques. A 10 Gbit/s differential quadrature phase shift keying （DQPSK） data signal is used at optical line terminal （OLT） for downstream, whereas a 2.5 Gbit/s inverse return-to-zero （IRZ） data signal with high extinction ratio is used for upstream signal by intensity re-modulation of downstream signal, no additional laser is used at optical network unit （ONU）. Simulation results verify that aggregated 100 Gbit/s downstream transmissions of 10 DQPSK channels and aggregated 25 Gbit/s upstream transmission of 10 IRZ channels, using spectrally-efficient 50 GHz channel spacing, can be successfully achieved over a distance of 20 km with less than 1 dB transmission power penalties and improved receiver sensitivity.     

A Hybrid System for Customer Churn Prediction and Retention Analysis via Supervised Learning

Telecom industry relies on churn prediction models to retain their customers. These prediction models help in precise and right time recognition of future switching by a group of customers to other service providers. Retention not only contributes to the profit of an organization, but it is also important for upholding a position in the competitive market. In the past, numerous churn prediction models have been proposed, but the current models have a number of flaws that prevent them from being used in real-world large-scale telecom datasets. These schemes, fail to incorporate frequently changing requirements. Data sparsity, noisy data, and the imbalanced nature of the dataset are the other main challenges for an accurate prediction. In this paper, we propose a hybrid model, name as “A Hybrid System for Customer Churn Prediction and Retention Analysis via Supervised Learning (HCPRs)” that used Synthetic Minority Over-Sampling Technique (SMOTE) and Particle Swarm Optimization (PSO) to address the issue of imbalance class data and feature selection. Data cleaning and normalization has been done on big Orange dataset contains 15000 features along with 50000 entities. Substantial experiments are performed to test and validate the model on Random Forest (RF), Linear Regression (LR), Naïve Bayes (NB) and XG-Boost. Results show that the proposed model when used with XGBoost classifier, has greater Accuracy Under Curve (AUC) of 98% as compared with other methods.     

Creep Behaviors of Two Near-Eutectic Al-Si-Cu-Mn Heat-Resistant Alloys Containing Dendritic Mn-Rich Primary Phase or Modified Star-Like Cr-Mn-Rich Primary Phase

In this study, the creep responses of two near-eutectic Al-Si-Cu-Mn alloys, Al-12wt pctSi-4 pctCu-1.2wt pctMn alloy (Alloy-1, containing dendritic Mn-rich primary phase) and Al-12wt pctSi-4 pctCu-2wt pctMn-1wt pctCr alloy (Alloy-2, containing star-like Cr-Mn rich primary phase), were investigated from 448 K to 523 K at 40 to 70 MPa applied stress. Results show that with 100 hours of exposure at 448 K/40 to 70 MPa, true steady-state creep was not attained. However, at 473 to 523 K/40 to 70 MPa, both the alloys showed a fixed creep rate establishing steady-state creep. The creep curves of the studied alloys illustrate that Alloy-1 exhibits lower creep rates and less creep strains than Alloy-2 in each combination of temperature and applied stress. Considering the creep rates and total creep strains after 100 hours of exposure, Alloy-1 possesses much better creep resistance than Alloy-2, even though the high-temperature strength of Alloy-2 is higher than that of Alloy-1 at 448 K and 523 K. Higher strength at high temperatures does not mean high creep resistance at high temperatures. At low to moderately high temperatures (0.48 to 0.53 T_m where T_m is the equilibrium melting point of pure Al in K) and applied stress of 40 to 70 MPa, the creep mechanisms in Alloy-1 and Alloy-2 are similar and diffusion is the rate-controlling process.

     

A novel process for physically refining rice bran oil through simultaneous degumming and dewaxing

A new process for the physical refining of rice bran oil through combined degumming and dewaxing was developed on a laboratory scale and then demonstrated on a commercial scale. The simultaneous degumming and dewaxing of the crude oil with a solution of water and CaCl₂, followed by crystallization at a low temperature (20°C), facilitated precipitation of the hydratable and nonhydratable phosphatides along with the wax, which enabled its separation and reduction to a greater extent. Bleaching and subsequent winterization (20°C) of this oil further reduced the phosphorus content to less than 5 ppm. Thus, these pretreatment steps enabled the physically refined rice bran oil to meet commercially acceptable levels for color, FFA content, and cloud point values (10–12 Lovibond units in a 1-in, cell, <0.25%, and 4–5°C, respectively) with very low neutral oil loss; this has not been observed hitherto. Rice bran oil is known for its high levels of bioactive phytochemicals, such as oryzanol, tocols, and sterols. The process reported here could retain more than 80% of these micronutrients in the end product. This paper was previously presented at the 95th AOCS Annual Meeting and Expo, Cincinnati, Ohio, May 9–12, 2004     

米糠油同时脱胶脱蜡物理精炼新技术

对米糠油同时脱胶脱蜡物理精炼新工艺进行了小试研究,并在此基础上进行了生产试验。毛米糠油与氯化钙水溶液混合,在低温下结晶(20℃)使水化磷脂和非水化磷脂与蜡一起沉析分离,随后进行脱色和冬化(20℃)处理,进一步将磷脂含量降到5 mg/kg以下,再经物理精炼,即可使成品精炼米糠油满足市售商品对其色泽(10~12罗维朋值,25.4 mm槽)、游离脂肪酸含量(<0.25%)和浊点(4~5℃)的要求;且中性油损失少。米糠油含有多种生物活性物质,如谷维素,VE和甾醇。本工艺可在最终产品中保留80%以上的生物活性物质。     

Maintaining design intent for aircraft manufacture

Design and manufacture of aircraft requires deep multi-disciplinary understanding of system behaviour. The intention of the designer can get lost due to the many changes occurring to the product and the inability of the methods and tools used to capture it. Systems engineering and optimisation tools underpin industrial approaches to design, but are not without issue. The challenge is to find a route from concept to manufacture which enables designers to maintain their original intent. The novelty in this work is that the parameterisation used to build the CAD model reflects the manufacturing capability, ensuring design intent is maintained from concept to manufacture.     

Elimination of solidification shrinkage defects in the casting of aluminum alloy

Journal of Mechanical Science and Technology - In this study, the analysis is carried out to optimize in-gate position and size of riser for casting mold. The baseline size of riser for the casting...