A systematic review of text stemming techniques

Stemming is a program that matches the morphological variants of the word to its root word. Stemming is extensively used as a pre-processing tool in the field of natural language processing, information retrieval, and language modeling. Though a lot of advancements have been made in the field, yet organized arrangement of the previous work and efforts are lacking in this field. In this paper, we present a review of the text stemming theory, algorithms, and applications. It first describes the existing literature relevant to text stemming by classifying it according to certain key parameters; then it describes the deep analysis of some well-known stemming algorithms on standard data sets. In the end, the current state-of-the-art and certain open issues related to unsupervised stemming are presented. The main aim of this paper is to provide an extensive and useful understanding of the important aspects of text stemming. The open issues and analysis of the current stemming techniques will help the researchers to think of new lines to conduct research in future.     

Effect of pretreatment conditions on physicochemical parameters of carrot juice

Carrot juice obtained by hydraulic press with wooden set-up was subjected to pretreatments (temperature, time and pH) prior to extraction process. Their effects on the most important quality parameters of carrot juice, such as beta-carotene, reducing sugars, pectin, vitamin C, viscosity, pH and acidity were studied. Response surface methodology was employed, where the experiment was carried out according to a central composite rotatable design. The variables ranges used were 61.50–98.50 °C (temperature), 124.55–595.45 s (time) and 2.31–6.69 (pH – concentration of citric acid). The results showed that beta-carotene extraction was significantly increased (52.9%) with these pretreatments in comparison to control samples. All the derived mathematical models for the responses were found to be fit significantly to predict the data. The responses were optimised by numerical method and were found to be 7190 μg per 100 g beta-carotene, 3.41% reducing sugars, 4.96 mg per 100 g vitamin C, 0.59% pectin, 1.64 × 10³ Ns m⁻² viscosity, 5.26 pH and 4.97% acidity at optimum input variables of 75.26 °C (temperature), 349.89 s (time) and 3.2 (pH). The desirability for all the responses was found to be 83.8%.     

Role of sintering temperature on thermal, electrical and structural properties of Y2Ti2O7 pyrochlores

Pyrochlores exhibit variety of properties which can be tailored by changing the processing conditions. In the present study, the sintering characteristics, thermal expansion coefficient, crystal structure and conductivity behavior of pyrochlores have been studied for different applications. It was observed that sintering at 1550 °C for 12 h exhibits more oxygen deficient YTiO_2.085 phase which shows two order of magnitudes higher conductivity than Y₂Ti₂O₇ phase. The conductivity enhancement in YTiO_2.085 sample is attributed to higher oxygen deficiency which may be created due to transformation of Ti⁴⁺ to Ti³⁺ at low oxygen pressure.     

Structural,thermal and electrical properties of Ti4+ substituted Bi2O3 solid systems

In the present study, the effect of TiO₂ doping on (1 ? x) Bi₂O₃ (x)TiO₂ (x = 0.05, 0.10, 0.15, 0.20) materials is investigated using X-ray diffraction (XRD), differential thermal analysis (DTA), ac conductivity, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). XRD results show the formation of single phase Bi₁₂TiO₂₀ at x ≥ 0.15 concentration of TiO₂. It is observed that, the lower concentration of TiO₂ leads to the formation of mixed phase. The x = 0.15 and x = 0.20 samples exhibit regular and uniform distribution of the grains as compared to x = 0.10 sample. The highest conductivity is observed for x = 0.15 specimen, e.g., 9 × 10^?7 S cm^?1.     

Tailor made exfoliated reduced graphene oxide nanosheets based on oxidative-exfoliation approach

This study presents a versatile and scalable strategy of ‘oxidation controlled exfoliation’ of rGO nanosheets synthesized from both Hummers and modified Hummers method. A co-relation between degree of oxidation of graphite oxide (GO) sheets and exfoliation of resulting synthesized rGO nanosheets has been successfully developed which in turn reflects in various properties of rGO sheets. The extent of exfoliation of rGO sheets has been well analyzed by XRD, SEM, BET and TEM techniques. Moreover, the quantitative analysis of degree of oxidation of GO has been estimated from FTIR spectra using quotient law method. The variations in number of rGO layers, defect density and sp² domain size have been investigated in detail by Raman spectroscopic technique. Both qualitative-quantitative analysis of rGO nanosheets have been discussed from their SAED pattern and HR-TEM images. The optical characterization of GO and corresponding rGO nanosheets has been studied in detail by UV- Vis spectroscopic technique.     

Heat-resistant thermosetting polyimide matrix resins containing keto,ether, hexafluoroisopropylidene linkages and maleimido- and nadimido- end capped groups

Various heat-resistant thermosetting polyimides containing hexafluoroisopropylidene and keto and ether groups suitable for fiber-reinforced composites development have been synthesised by thermal polymerization of maleimido and nadimido end capped polymer precursors. Thermal polymerization involving addition reactions was performed at 225°C for 1.5 h and post-curing at 290°C for 0.5 h. Tough polymers XVIII to XXIII were obtained. The thermal polymerization was monitored using infrared spectroscopy. The polymer precursors were characterized by IR, ¹H-NMR, and elemental analysis. The synthesized polymers were evaluated for thermal stability using dynamic thermogravimetric analysis (TGA). All the polymers showed thermal decomposition temperatures in the range of 430–435°C in nitrogen and in air. The char yield of the polymers was in the range of 60–67% in nitrogen at 800°C. This study indicated that thermally synthesized polymers from hexafluoroisopropylidene, keto, and ether containing polymides are potential candidates for the development of advanced materials for aerospace and high-tech applications. © 1993 John Wiley & Sons, Inc.     

Exploring expert opinion on the practicality and effectiveness of biosecurity measures on dairy farms in the United Kingdom using choice modeling

Biosecurity, defined as a series of measures aiming to stop disease-causing agents entering or leaving an area where farm animals are present, is very important for the continuing economic viability of the United Kingdom dairy sector, and for animal welfare. This study gathered expert opinion from farmers, veterinarians, consultants, academics, and government and industry representatives on the practicality and effectiveness of different biosecurity measures on dairy farms. The study used best-worst scaling, a technique that allows for greater discrimination between choices and avoids the variability in interpretation associated with other methods, such as Likert scales and ranking methods. Keeping a closed herd was rated as the most effective measure overall, and maintaining regular contact with the veterinarian was the most practical measure. Measures relating to knowledge, planning, and veterinary involvement; buying-in practices; and quarantine and treatment scored highly for effectiveness overall. Measures relating to visitors, equipment, pest control, and hygiene scored much lower for effectiveness. Overall, measures relating to direct animal-to-animal contact scored much higher for effectiveness than measures relating to indirect disease transmission. Some of the most effective measures were also rated as the least practical, such as keeping a closed herd and avoiding nose-to-nose contact between contiguous animals, suggesting that real barriers exist for farmers when implementing biosecurity measures on dairy farms. We observed heterogeneity in expert opinion on biosecurity measures; for example, veterinarians rated the effectiveness of consulting the veterinarian on biosecurity significantly more highly than dairy farmers, suggesting a greater need for veterinarians to promote their services on-farm. Still, both groups rated it as a practical measure, suggesting that the farmer-veterinarian relationship holds some advantages for the promotion of biosecurity.     

The effect of matrix morphology on nanocomposite properties

In order to understand the effect of bulk matrix morphology on polymer nanocomposite properties, nanocomposites containing chemically similar but morphologically different polyamide matrices and carbon nanofibers were processed and characterized. Two polyamide matrices were used, one amorphous and one semi-crystalline. Experimental results indicated that the reinforcing efficacy of the amorphous matrix was higher than the semi-crystalline matrix at temperatures below the glass transition. At a carbon nanofiber loading of 0.5 wt.%, the experimentally measured modulus with the amorphous matrix exceeded the Halpin-Tsai prediction for an isotropic material. Overall, these results provided distinct evidence that the underlying bulk matrix morphology plays an important role in polymer nanocomposite mechanical design.     

Experimental Evaluation of Topology Control and Synchronization for In-Building Sensor Network Applications

While multi-hop networks consisting of 100s or 1000s of inexpensive embedded sensors are emerging as a means of mining data from the environment, inadequate network lifetime remains a major impediment to real-world deployment. This paper describes several applications deployed throughout our building that monitor conference room occupancy and environmental statistics and provide access to room reservation status. Because it is often infeasible to locate sensors and display devices near power outlets, we designed two protocols that allow energy conservation in a large class of sensor network applications. The first protocol, Relay Organization (ReOrg), is a topology control protocol which systematically shifts the network’s routing burden to energy-rich nodes, exploiting heterogeneity. The second protocol, Relay Synchronization (ReSync), is a MAC protocol that extends network lifetime by allowing nodes to sleep most of the time, yet wake to receive packets. When combined, ReOrg and ReSync lower the duty cycle of the nodes, extending network lifetime. To our knowledge, this research provides the first experimental testbed evaluation of energy-aware topology control integrated with energy-saving synchronization. Using a 54-node testbed, we demonstrate an 82–92% reduction in energy consumption, depending on traffic load. By rotating the burden of routing, our protocols can extend network lifetime by 5–10 times. Finally, we demonstrate that a small number of wall-powered nodes can significantly improve the lifetime of a battery-powered network. W. Steven Conner is a Wireless Network Architect in the Communications Technology Lab, Intel Research and Development. He currently leads a team developing self-configuring wireless mesh networking technology and is an active participant in IEEE 802.11 standards development. His current research interests include wireless mesh networking, sensor networks, and network self-configuration protocols. He received B.S. and M.S. degrees from the University of Arizona. Jasmeet Chhabra received B.E. (1996) and M.S. (1999) degrees from University of Delhi and University of Maryland, College Park, respectively. Since 1999 he has been a researcher in the Communications Technology Lab, Intel Research and Development. His current research interests include sensor networks, ubiquitous computing, mesh networks and security. Mark Yarvis received B.S. (1991), M.S. (1998), and Ph.D. (2001) degrees in computer science from the University of California, Los Angeles. Since 2001, he has been a Senior Researcher in the Communications Technology Lab, Intel Research and Development. He is currently the principle investigator of the Intel Research Heterogeneous Sensor Networking project. His research interests include heterogeneous systems, sensor networks, and pervasive and mobile computing. He is a member of IEEE and ACM. WWW: Lakshman Krishnamurthy manages the radio networks initiative in the Intel Corporate Technology Group and is also the principal investigator of the EcoSense wireless sensor network Strategic Research Project. He leads research efforts into new wireless mesh protocols and techniques to provide ease of use and improve performance of wireless networks. As part of the EcoSense project, Lakshman is driving wireless sensing into Intel fabs by piloting a preventative maintenance application. Currently, he also serves on the program committees of the ACM SenSyS and IEEE SECOM conferences. Lakshman received a Ph.D in computer science from the University of Kentucky and a BE in instrumentation technology from the University of Mysore, India.This revised version was published online in August 2005 with a corrected cover date.