Data Preparation for Mining World Wide Web Browsing Patterns

The World Wide Web (WWW) continues to grow at an astounding rate in both the sheer volume of traffic and the size and complexity of Web sites. The complexity of tasks such as Web site design, Web server design, and of simply navigating through a Web site have increased along with this growth. An important input to these design tasks is the analysis of how a Web site is being used. Usage analysis includes straightforward statistics, such as page access frequency, as well as more sophisticated forms of analysis, such as finding the common traversal paths through a Web site. Web Usage Mining is the application of data mining techniques to usage logs of large Web data repositories in order to produce results that can be used in the design tasks mentioned above. However, there are several preprocessing tasks that must be performed prior to applying data mining algorithms to the data collected from server logs. This paper presents several data preparation techniques in order to identify unique users and user sessions. Also, a method to divide user sessions into semantically meaningful transactions is defined and successfully tested against two other methods. Transactions identified by the proposed methods are used to discover association rules from real world data using the WEBMINER system [15].     

Integrating quality and maintenance decisions in a production-inventory model for deteriorating items

In typical production-inventory models of deteriorating items, deterioration of the production process has not been considered. In this paper, a model is proposed in which both the produced items and the production equipment deteriorate. When the production system deteriorates, it shifts to an out-of-control state and begins to produce a proportion of defective items, necessitating corrective maintenance action. A model is formulated to integrate several realistic aspects, including item and process deterioration, varying demand and production rates, quality, inspection, and maintenance. A heuristic solution algorithm is developed to determine the production and inspection schedules, and a numerical example is solved.     

Novel PDMS‐based membranes: Sodium chloride and glucose permeability

Permeation of sodium chloride and glucose through polydimethylsiloxane‐poly(N‐isopropylacrylamide) (PDMS‐PNIPAAm) interpenetrating polymer networks (IPNs) of two different microstructures was investigated. We have successfully developed small‐molecule permeable IPNs, by modifying PDMS film structure. A group of PDMS films was prepared using conventional solvent casting (SC) method and another group produced by introducing oil, followed by SC and leaching the oil out (SCOL method). Scanning electron microscopy (SEM) and attenuated total reflection fourier transformer infrared (ATR‐FTIR) spectroscopy results confirmed the presence of PNIPAAm in the SC and SCOL IPNs. Results obtained from spectra of differential scanning calorimetry (DSC) showed that these IPNs had a phase transition temperature at about 32°C. Permeation measurements showed that the presence of PNIPAAm as the second phase in the IPN, improved the permeability of PDMS film. According to the results, maximum permeation coefficient was related to SCOL IPN containing 15.8% ± 0.3%PNIPAAm, at 23°C (5.98 × 10^?7 ± 7.93 × 10^?9 cm²/s for sodium chloride and 3.6 × 10^?7 ± 7 × 10^?9 cm²/s for glucose). These results suggested that these PDMS‐PNIPAAm IPNs with sodium chloride and glucose permeability may be further developed as ophthalmic biomaterials or corneal replacements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Image Analyses-Based Nondisruptive Method to Quantify Algal Growth on Concrete Surfaces

A global ban on the use of tributyltin has resulted in the need to screen new antifouling agents to control algal growth in aquatic environments. Standard methods for the quantification of algal biomass are disruptive in nature; therefore, they are not applicable for the screening studies requiring successive observations at specified time intervals. The objective of this study was to develop a nondisruptive method to quantify algal growth on a variety of surfaces. Image analyses and chlorophyll extraction methods were used to quantify an algal biomass on a concrete surface containing different additives. For concrete samples containing single additives, the coefficient of determination between both techniques ranged from 0.74 to 0.84. However, for concrete samples containing multiple additives, the coefficient of determination of both methods ranged from 0.72 to 0.75. Results suggest that an image analyses technique can be used to accurately quantify various types of algae growing on a variety of solid surfaces.     

β-Galactosidase in the acceleration of Ras cheese ripening

An attempt has been carried out to accelerate Ras cheese ripening by pre-treatment of cheese milk with β-galactosidase. Milk was treated with a β-galactosidase enzyme preparation, namely lactozym (1 ml/kg milk), at 33°C for 1 h or at 4°C for 18 h and used for Ras cheese making. Flavour intensity, formation of soluble nitrogen compounds, free amino acids and liberation of free fatty acids were enhanced in cheese made from β-galactosidase treated milk. In addition, the ripening period was reduced to 2 months compared with 4 months required for control cheese. Treatment of cheese milk with β-galactosidase at 4°C or 33°C showed a similar effect on the properties of cheese.     

A case study and troubleshooting experience of safety power channel of instrumentation and control system of the BAEC TRIGA Research Reactor

Microsystem Technologies - Bangladesh Atomic Energy Commission TRIGA Research Reactor (BTRR) is a MK II type nuclear research reactor with a maximum thermal output power of 3 MW. Nuclear...     

Hemodialysis membranes prepared from poly(vinyl alcohol): Effects of the preparation conditions on the morphology and performance

Poly(vinyl alcohol) was employed for the preparation of hemodialysis membranes with and without the addition of acetic acid and poly(ethylene glycol) with the phase‐inversion process. Aqueous solutions of sodium sulfate and sodium hydroxide were chosen as coagulant baths. The performances of the membranes were estimated by the measurement of the removal of uremic toxins (urea, uric acid, and creatinine) from human blood serum. The morphologies of the membranes were investigated and correlated to the membrane performance. Increasing the poly(ethylene glycol) concentration in the polymer solutions resulted in porous, spongelike structures because of the higher polarity of the polymer solutions and the enhancement of the diffusion rate of the nonsolvent (sodium sulfate and sodium hydroxide) into the polymer solutions. The porous structures of the membranes enhanced the removal of uremic toxins. The presence of acetic acid, with greater ionization strength, resulted in higher electrostatic interactions between positive and negative ions in the coagulation baths and polymer solutions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2490–2497, 2007     

Non-contacting strain measurement for cement-based composites in dynamic tensile testing

This paper presents the development of a test procedure and application of non-contacting strain measurement for cement-based composites under moderately high strain rate tensile tests. The strain time histories of test specimens measured by a laser extensometer in high speed mode were derived by a phase-shift technique based on zero-crossing method. The accuracy of the linear variable differential transformer (LVDT) of the actuator in a servo-hydraulic high rate testing machine was verified by image analysis using sisal fiber reinforced cement composite at a strain rate of 25 s⁻¹. The same procedure was then applied to Alkaline Resistant (AR) glass fabric reinforced cement composite tested at an average strain rate of 17 s⁻¹. Comparison between the strain values measured by the laser extensometer and the LVDT shows a good agreement between these two measurement techniques. The test results show that the Young’s modulus, tensile strength, maximum strain, and toughness of the AR-glass fabric-cement composite increase with increasing strain rate. However, under both static and dynamic loadings the composite has similar behavior: multi-crack development and one dominant crack leading to final failure. In order to ensure the accuracy of dynamic tensile test procedures, non-contacting devices and techniques should be used as an independent means of verification of test results. The accuracy required in quantifying relative improvements in mechanical properties necessitates the various methods of measuring the displacement and strain rate properties.     

Amylopectin Multiple Aldehyde Crosslinked Hydrogel as an Injectable and Self‐Healing Cell Carrier for Bone Tissue Engineering

Despite excellent processing and biological properties of gelatin for use as a cell carrier, none of the gelatin‐based hydrogel cell carriers reported to date offer all characteristics including quick formation, injectability, self‐healing, and durability, which are simultaneously required for an ideal system. Here, a gelatin‐based hydrogel with dynamic Schiff base linkages, so‐called “dynamic hydrogel,” as an injectable cell carrier consisting of gelatin and amylopectin multiple aldehyde (AMPA), with all the required characteristics is reported. Biocompatibility and osteoinductivity of the hydrogel are verified through the culture of human bone marrow‐derived mesenchymal stem cells (hBMSCs). As live/dead results show, hBMSCs are alive and highly viable ≈85–90% within the hydrogel after 5 days. According to bromodeoxyuridine cell proliferation assay, a significant increase in the number of the cells seeded in the hydrogel confirms its clinical significance for cell therapy. Most importantly, histological visualization using Mason's Trichrome staining indicates secretion of extracellular matrix around the cells loaded in the hydrogel and also expression level evaluation of the crucial osteogenic markers, confirms that the hydrogel can provide osteoinductive support for osteocyte differentiation of hBMSCs after 14 days. Therefore, this hydrogel provides more progress on the path toward bone tissue engineering and further treatment of bone diseases.