Strip yield modelling of fatigue crack under variable amplitude loading

The results from 'strip yield' approach of the FASTRAN type models of plasticity induced crack closure effects of fatigue cracks subjected to variable amplitude loadings are presented. The strip yield results are compared with authors' finite element (FE) and experimental results. It has been observed that the strip yield model is seen to be fundamentally limited by choice of alpha (constraint factor) and corresponding to treat baseline closure effects. Double overload closure behavior is functionally similar for both strip yield and FE models. Under multiple overloads, an important functional difference is seen between FE and strip yield models. This has been linked to the absence of in-plane constraint in the strip yield model, which is seen to have a distinct decreasing influence on on-going closure effects.Peer reviewedFinal Accepted Versio

Exploration of Product Reviews

E-commerce is a popular platform for trade of products and services through the Internet. Product reviews play a vital role in e-commerce by influencing the purchasing decision of customers. As many products have thousands of reviews, it is difficult to explore and extract useful information from them. We need review exploration systems to help users quickly explore and comprehend huge volumes of reviews. The current review exploration systems lack effective means of finding relevant review and summarizing them. In this thesis, we present three limitations of existing review exploration systems and propose solutions to address each of the three limitations. Existing aspect based review summarization systems do not show the semantic relations that exist between aspects, which is required for proper exploration of reviews. We address this limitation by showing users an aspect ontology tree, which is created in an unsupervised manner from reviews, to show the relationship between aspects and sub-aspects. We then allow users to navigate reviews according to the aspects of the ontology. Many of the existing review exploration systems summarize reviews by giving an average star rating of the reviews, or by finding the number of positive and negative reviews for each of the aspects. Such summarization methods do not show the actual opinion words of users, which is crucial to understand what other users like or don’t like. We address the problem of summarizing reviews by creating informative and readable tags. We present a novel unsupervised method to generate the top-k opinionated tags. We also address the problem of tag generation for cold products, which have only a limited number of reviews and that too, with very limited content. Finally, we study the problem of stance detection in comparative reviews using word-embeddings. Online debate sites are popular platforms for users to express and form opinions. Comparative reviews are very popular as they give a comparison of different aspects of two competing products. Standard aspect-based summarization approaches cannot be used for comparative reviews as we need to figure out the target preference of each of the aspects, which is often not explicitly available in the review text. We propose an unsupervised approach to summarize comparative reviews by detecting the stance of users from comparative reviews

Synthesizing and Reviewing Research Trends in Automation

The objective of this paper is to develop a thorough understanding of the evolution of automation techniques throughout its time span. To achieve this, a literature review followed by classification schemes and simple Meta analysis have been presented in this paper. The literature review was based on journals collected for the study. A total of 234 articles were selected for the study. The study yielded 37 variables which formed the basis of classification schemes. The first classification scheme was conceptual while the second was functional. The entire study was grouped into these classification schemes. The classification schemes were the foundations for performing simple Meta analysis. The analysis was done under three categories, according to classification schemes, according to year of publication and according to journals. The results show various trends of automation throughout the years. In the end, the results are discussed in detail and future areas of research are identified. Keywords: Automation techniques, Classification schemes, Meta analysis, Primary dimension

Rice Cultivation - A Way of Life for the People of North Eastern Hill Region of India

Being an amazing picturesque of land, the North Eastern Hill Region of India, consisting of more than 200 ethnic groups, has only about 2.27% of the total rice area and shares only 1.96% of the total rice production in the country. Whether profitable or not, the rice cultivation is a way of life for the people of North Eastern Hill Region of India. Till today, the production and productivity of rice in this region is below the national average because of its fragile ecosystem and the varied physio-graphic conditions pertaining to this region. Neither the wider recommendation of agricultural technology such as variety nor the use of a single technology or variety can solve this problem of low yield. However, the development of location specific high yielding rice variety using the existing land races prevalent in the area can be one of the promising technique for improving the production and productivity of rice cultivation in this region

Screening lentil (Lens culinaris) RIL population for high yield and aluminium toxicity tolerance under acidic field and hydroponic conditions

The present study was carried out during winter (rabi) season of 2020–21 at two locations namely the experimental field of College of Post Graduate Studies in Agricultural Sciences (Central Agricultural University, Imphal, Manipur), Umiam, Meghalaya and Agro-forestry experimental plot of ICAR-North-Eastern Hill Region, Meghalaya followed by hydroponics screening during winter (rabi) season of 2021–22. The experiments involved screening of a recombinant inbred line (RIL) population of lentil (Lens culinaris Medik) obtained from a cross between BM-4 (Al sensitive parent) and L-4602 (Al tolerant parent) for high yield and Al (aluminium) toxicity tolerance through evaluation in the acidic field conditions, character association studies and root growth studies under hydroponics having toxic Al concentration of 148 µM. Highly significant variance due to genotypes revealed presence of sufficient variability for all the traits except number of seeds/pod (SP). Among the characters, high Hbs2 associated with high GA% were recorded in number of primary branches/plant (NB), plant height (PH) and 100-seed weight (SW). Path analysis revealed that, number of pods/plant (PP) (0.840) had the greatest direct effects in influencing seed yield/plant (SYPP), followed by biological yield/plant (BYPP) (0.795), number of seeds/pod (SP) (0.474), number of primary branches/plant (NB) (0.309) and harvest index (HI) (0.307). Correlation studies among root and shoot parameters under hydroponic studies revealed significant correlation between root dry weight (RDW) and shoot dry weight (SDW); shoot fresh weight (SFW) and root fresh weight (RFW); total root length (TRL) and surface area (SA); and haematoxylin stain score (STNS) and root regrowth (RRG). Based on mean performance of SYPP and attributing traits, combined with root growth studies under hydroponics, the high yielding and Al toxicity tolerant genotypes identified were LRIL-37, LRIL-22, LRIL-68, LRIL-96 and LRIL-97. In addition to serving as parents in hybridization programmes, these genotypes may undergo additional evaluation in multiple environments prior to final release in an effort to enhance performance

Genetic variability and association study of SSR markers for yield and powdery mildew disease in pea (Pisum sativum)

Makhyatmubi, one of the most popular local varieties of field pea (Pisum sativum L.) in Manipur has morpho- physiological bottlenecks such as tall nature and high susceptibility to fungus Erysiphe pisi causing powdery mildew disease. Therefore, an experiment was conducted during winter (rabi) seasons of 2018–19 and 2020–21 at College of Post-Graduate Studies in Agricultural Sciences (Central Agricultural University, Imphal, Manipur), Umiam, Meghalaya to generate genetic variability by hybridization of Makhyatmubi with Prakash variety which is a well-known powdery mildew resistant variety in India and possesses several contrasting characters. Fruitful heterosis was estimated with highest record in number of pods per plant (114.75%) and seed yield per plant (108.04%). These two characters also showed high PCV, GCV, heritability and GAM. Number of pods per plant (0.95) was found to have highest positive significant correlation with seed yield per plant. MP-5 and MP-119 recorded superior performance in several characters under study. For the association study of simple sequence repeats (SSR) markers, easily scorable polymorphic markers were selected for surveying association with the traits. Results revealed that SSR marker AA122 may be associated with seed yield and number of pods per plant while marker AA136 with number of seeds per pod. A5 marker was found to be associated with the powdery mildew disease. Hence, it can be employed for marker assisted selection (MAS) to identify and select pea genotypes exhibit resistance to powdery mildew disease

Deciphering growth abilities of fusarium oxysporum f. sp. pisi under variable temperature, pH and nitrogen

Fusarium wilt caused by Fusarium oxysporum f. sp. pisi (Fop) is an important disease and major obstacle to pea production, causing huge losses to growers. The focus of this study was on isolation followed by morphological, molecular characterization and analyzing the growth of the casual agent under variable temperature, pH and Nitrogen levels. The morphological features of radial growth, sporulation, pigmentation and mycelial characterization were examined and the variability of all isolates was presented. Molecular characterization of the fungus by ITS rDNA sequencing revealed that all 13 isolates belong to Fusarium oxysporum species. Six isolates were tested for temperature, pH and nitrogen dosage optimization studies. Seven different temperatures, viz., 21, 23, 25, 27, 29, 31, 33°C and pH values, having 3, 4, 5, 6, 7, 8, and 9 pH, as well as nitrogen dosage levels of 0 g, 3 g, 5 g, 7 g, 9 g, 11 g, and 13 g were tested against all six isolates, respectively. The results showed that all isolates exhibited the highest growth at a temperature of 25°C and the optimal temperature range for growth of Fusarium oxysporum was 23–27°C. All isolates showed the highest growth at pH5. Change in the nitrogen doses of the base ended in formation of thick, dense, fluffy mycelium of the casual agent. Six isolates were used for combination studies with seven different levels of temperatures, pH levels and nitrogen dosages. The density plots revealed the variations in the growth of the isolates with changes in temperature, pH and nitrogen levels, which can lead to mutations or genetic changes in the pathogens that could potentially introduce new threats to pea cultivation

Modelling of combined roughness and plasticity induced closure effects in high strength Al-alloys

An investigation of plasticity induced crack closure (PICC) and roughness induced crack closure (RIC C) behaviour using finite element (FE) methods is presented for cracks subjected to small scale yielding (SSY) conditions. For constant amplitude (CA) undeflected cracks have been examined under both plane strain and plane stress conditions, whilst plane strain analyses have been particularly considered for deflected cracks. A previous two dimensional analytical treatment of RICC (2D CA RICC) [Parry, 2000] has been extended to produce a 'continuous' closure model matching the FE findings. The model is further modified to address three dimensional effects and compared to detailed experimental findings. Results shows the increase in closure levels with increasing twist angle (rjJ) are less significant compared to that with increasing tilt angle (8). Further FE modelling of PICC and RICC for cracks subjected to single overloads is presented. A single overload analytical model of PICC proposed by Parry has been modified following similar arguments to the CA-RICC model. The analytical model has further been modified to address RICC effects during single overloads. Effects of Llrp ratios on deflected cracks during overloads are seen to be functionally similar to RICC under constant amplitude loading (particularly in the 'saturation' of RICC influence for Llrp(OL) &gt; 1), where L, rp and rp(OL) are deflected crack length, baseline plastic zone size and overload plastic zone size respectively. Competitive influences of PICC and RICC effects during single overloads are identified in both the FE and simplified analytical models. A modified 'strip yield' analytical model of the 'FASTRAN'-type [Xu, 2001] has also been used to study PICe effects during single overloads. Comparisons of models and experimental closure and growth rate studies are presented. Investigations have then been extended to consider both double and multiple overload conditions. In particular, attempts are made to study the effects of overload spacing on closure levels and growth rates. It appears to exist a maximum overload interaction zone for double overloads which severity of overload closure effect is at its greatest. Overall it is found that key functional aspects of the various FE models are reproducible in simple analytical representations of RICC and PICC efforts. Whilst some fitting is involved, good correlation of the present analytical models and experimental data is shown, opening a potential route to improve, computationally efficient, multimechanistic fatigue lifing methods involving crack closure.</p

Modelling of combined roughness and plasticity induced closure effects in high strength Al-alloys

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