Environmentally sustainable rice husk ash reinforced cardanol based polybenzoxazine bio-composites for insulation applications

Polymer Bulletin - Tri-substituted cardanol based benzoxazine with functionalized rice husk ash (CBz/FRHA) bio-composites were developed using renewable resource materials, and...     

Analysis of fluid flow in centrifugal casting

Centrifugal casting process is a fast process with melt, cast and moulds being opaque. It is almost impossible to observe the melt behavior during casting. Cold modeling experiments were conducted using horizontal transparent moulds and transparent fluids of different viscosities to study the effect of different process variables on the flow pattern. Effects of the thickness of fluid cylinder, viscosity of the fluid, diameter of the mould, and rotational speed of the mould on the formation of complete hollow fluid cylinder are investigated. The influence of rotational speed has been studied in aluminum casting. The cylinders are cast at different rotational speed with varying thickness. It is observed that the speed required to form uniform cylinder increases with the increase in thickness of a fluid cylinder. As rotational speed is increased the hardness of the cast cylinder also increases. The flow patterns seen in cold modeling experiments and actual castings agree reasonably well.     

Effects of personal,psychosocial and occupational factors on low back pain severity in workers

Low back pain (LBP) remains the most common work-related musculoskeletal disorder (WMSD). While most of the LBP research has focused on occupational risk factors, other underlying causal mechanisms may exist since not all workers performing the same task develop an injury. Previous research has identified three primary risk factor categories for LBP (occupational, personal and psychosocial factors); however, few studies have investigated the impact of cross categorical risk factor interactions on LBP. The objective of this study was to investigate the effects of occupational, personal and psychosocial factors, and their interactions, on LBP severity in a population of workers currently suffering from LBP. Sixty LBP patients recruited for the study through local physicians and local announcements, completed questionnaires relating to identified occupational, personal and psychosocial risk factors, and completed an Oswestry Disability Index (ODI). Multiple regression models for predicting LBP severity were developed for each risk factor category and for a combined risk factor model (which included factors from all three risk factor categories) that included two-way interactions. Results showed that the final model consisted of both main effects and interaction terms between risk factor categories and had an adjusted R² value of 0.85, a significant improvement over models developed for the individual categories. These findings illustrate the need to consider all three broad categories of risk factors simultaneously in predicting injury status and in developing effective potential intervention efforts.     

Improvements to the SMO algorithm for SVM regression

This paper points out an important source of inefficiency in Smola and Scholkopf's (1998) sequential minimal optimization (SMO) algorithm for support vector machine regression that is caused by the use of a single threshold value. Using clues from the Karush-Kuhn-Tucker conditions for the dual problem, two threshold parameters are employed to derive modifications of SMO for regression. These modified algorithms perform significantly faster than the original SMO on the datasets tried.     

复合式膜生物反应器在制革污水处理中的应用发展

考察了复合式膜生物反应器(HMBR),即电絮凝、生化和微滤过程,对制革污水中的COD和色度的去除效果。分析了电流密度和pH值在电絮凝过程中的影响,并优化了电絮凝过程。将优化后的电絮凝过程和活性污泥法(ASP)、末端微滤(MF)相结合,应用于制革污水处理中。结果表明:复合过程可以有效提升污水的处理质量。对比膜生物反应器(MBR)和HMBR的处理效果,HMBR的最大COD去除率和脱色率分别为90.2%和92.75%,而MBR的最大COD去除率和脱色率分别为72.69%和75.82%。使用SEM-EDAX分析HMBR过程中附着在膜表面的滤饼层,表明将MBR和电絮凝法结合后,膜上的污垢显著减少。     

Honeypot Based Black-Hole Attack Confirmation in a MANET

Many solutions are proposed to identify or prevent the attacks in a Mobile Ad hoc Network. However, sometimes these systems detect false attacks. This could lead to loss of resources in a mobile ad hoc network and cause a downgrade in quality of service. Hence mobile ad hoc networks need a system to confirm the attack before taking further actions. In our work presented in this paper, we propose an attack confirm system for a malicious attacker, called the Black-hole attacker. We present our Black-hole attack Confirmation System, which identifies and confirms the black-hole attack in a mobile ad hoc network using honeypot. The honeypot intelligently identifies all the possible types of black-hole attack using the Black-hole Attack tree, and confirms the attack using the Attack History Database. Together, the Black-hole Attack tree, and Attack History Database aid the honeypot in reducing the false alarms in the mobile ad hoc network. We have simulated the proposed system in several mobile ad hoc network environments of varying sizes of nodes and applications. On several occasions the results have demonstrated that the proposed system is efficient in confirming the black-hole attack and saving the resources and minimizing the path re-establishment.     

Asymptotic behaviors of support vector machines with Gaussian kernel

Support vector machines (SVMs) with the gaussian (RBF) kernel have been popular for practical use. Model selection in this class of SVMs involves two hyperparameters: the penalty parameter C and the kernel width sigma. This letter analyzes the behavior of the SVM classifier when these hyperparameters take very small or very large values. Our results help in understanding the hyperparameter space that leads to an efficient heuristic method of searching for hyperparameter values with small generalization errors. The analysis also indicates that if complete model selection using the gaussian kernel has been conducted, there is no need to consider linear SVM.     

Solubility and solution thermodynamic properties of quercetin and quercetin dihydrate in subcritical water

Fundamental physicochemical data is required for the design and optimization of food engineering processes, such as extraction. Flavonoids are present in natural products such as grapes and have numerous health benefits particularly with respect to their reported antioxidant properties. Such flavonoid compounds can be extracted from these natural products using a variety of solvents, among them water. In this study, the aqueous solubilities of 3,3′,4′,5,7-pentahydroxyflavone (quercetin) and its dihydrate were measured at temperatures between 25 and 140 °C using a continuous flow type apparatus. The flow rate of subcritical water was studied at 0.1, 0.2 and 0.5 mL/min to study its effect on quercetin solubility and thermal degradation at temperatures greater than 100 °C. The aqueous solubility of anhydrous quercetin varied from 0.00215 g/L at 25 °C to 0.665 g/L at 140 °C and that of quercetin dihydrate varied from 0.00263 g/L at 25 °C to 1.49 g/L at 140 °C. The aqueous solubility of quercetin dihydrate was similar to that of anhydrous quercetin until 80 °C. At temperatures above or equal to 100 °C, the aqueous solubility of quercetin dihydrate was 1.5–2.5 times higher than that of anhydrous quercetin. The aqueous solubility of quercetin anhydrate and dihydrate at different temperatures was correlated using a modified Apelblat equation. The thermodynamic properties of the solution of quercetin and its dihydrate in water were than estimated from their solubility values. A flow rate effect on the aqueous solubility of quercetin and its dihydrate was not observed until above 100 °C where higher solvent (water) flow rates (>0.1 mL/min) were required to maintain a constant solubility in the saturation cell and with minimal thermal degradation of the solute (quercetin dihydrate). The study of its particle morphology under SEM indicated an aggregation of the crystals of quercetin dihydrate at subcritical water temperatures and at lower flow rates (<0.5 mL/min), thereby inhibiting stable solubility measurements and solvent flow through the saturation cell.     

Binder-free,non-carcinogenic surfactant-based cellulose-rich bagasse foams as acoustic panels

Toward identifying environmentally friendly sound-absorbing materials, the fabrication of biodegradable bagasse foams and their acoustic absorption and transmission loss were investigated. 10-mm-thick bagasse foams were fabricated using different concentrations of four non-carcinogenic surfactants: sodium dodecyl sulfate (SDS), sodium bicarbonate (SB), potassium oleate (PO), and polyoxyethylene sorbitol ester (T20). Electron microscopy revealed that the foams comprised microfibers with a 10%–25% porosity. The foams were found to be thermally stable up to 300 °C. While foams fabricated using SDS were found to have a maximum increment in acoustic absorption (by 200%), those made of T20 had a mild decrease in absorption. The increment in absorption was attributed to the decrease in crystallinity and increase in porosity of microstructure, and the decrement to the decrease in viscous nature. Minimal changes were observed in the transmission loss of the foams. The results presented here demonstrate a simple, scalable green method to fabricate porous biodegradable foams of bagasse, without using any binder or filler, suitable for acoustic insulation that fits sustainable development objectives.     

A Fast Dual Algorithm for Kernel Logistic Regression

This paper gives a new iterative algorithm for kernel logistic regression. It is based on the solution of a dual problem using ideas similar to those of the Sequential Minimal Optimization algorithm for Support Vector Machines. Asymptotic convergence of the algorithm is proved. Computational experiments show that the algorithm is robust and fast. The algorithmic ideas can also be used to give a fast dual algorithm for solving the optimization problem arising in the inner loop of Gaussian Process classifiers. Editor: Shai Ben-David