Damage Assessment in Composite Structures using System Identification

In recent years, the use of fibre-reinforced composite laminates in aerospace, mechanical, and other structural applications has become very popular due to their low density and attractive mechanical properties. However, the low inter-laminar strength of composite laminates makes them predisposed to internal damage in the form of delamination, which leads to loss of structural integrity. It is necessary to detect and assess the severity of possible delamination damage, particularly in aircraft components as early as possible in order to ensure safe operation and prevent loss of life. Detection of delaminations in composite laminates using traditional NDI techniques such as, ultrasonic testing requires aircraft to be grounded, which significantly increases maintenance cost. Implementation of structural health monitoring techniques, which can be applied online and in situ is desirable both in terms of reducing cost as well as detecting damage as soon as it occurs. Vibration monitoring offers promise in this regard. This thesis investigates the use of system identification using vibration measurements to detect and assess delaminations in composite laminates. System identification involves constructing a dynamic model of the structure through identifying system parameters from the measured dynamic response of the structure. In this study, State Space Finite Element System is employed to construct the model and the system parameters such as stiffness and damping are identified using Eigen Realization Algorithm (ERA) from the response of the structure to impulse or other forms of excitation. Damage is identified and located from unexpected variations in the system parameters, specifically, the element stiffness coefficients. A methodology is developed to assess the severity of damage by comparing the reductions in estimated stiffness values to those predicted by theory for the undamaged laminate. The proposed damage assessment technique is first applied to composite beams with simulated delaminations and then extended to composite plates. It is shown that the system identification using ERA in conjunction with State Space Finite Element System Model (SS-FESM) is able to identify delaminations in composite laminates and determine the in-plane location, size and severity (dependent on the interface location of delamination) from measured dynamic responses to impulse or chirp excitation, even in the presence of noise

The Scenario of Buffalo Production and Research in Bangladesh

Background: This study aimed to characterize the scenario of buffalo production in the northern part of Bangladesh and review the published scientific literature on buffalo from Bangladesh. Methods: The study was conducted from August to December 2022. A draft questionnaire was prepared and modified before the final one based on the study's objectives. Data were collected through personal interviews with individual respondents. In addition, the review article was collected on buffalo from Google, Google Scholar, Research Gate, Scopus, Bangladesh Journal-Online (BJO), and PubMed. Results: Data was collected from 1099 animals from the northern part of the Natore and Lalmonirhat districts of Bangladesh. Most of the farmers were illiterate, and the age was above 40 years. Regarding the purpose of buffalo production, 69.16% (n=83) of the farmers narrated that they are motivated to milk with calves selling. The average herd size was about 9 and consisted of indigenous and crossbred buffaloes. Most of the farmers kept their buffalo in the Bathan. The coat color was predominantly black, with brown hair. Farmers 94.16% (n=113) practice de-worming, and the frequency was thrice a year. Wallowing is performed at least once a day in the pond or river for the thermal regulation of the buffalo. Among the farmers, 67.50% (n=81) have no training in rearing buffalo. Farmers practice natural mating by their own or neighbor bull to serve the heated cow. Sometimes it’s free, or sometimes, with payment on an average of BDT 400-500 or 3.79-4.73 US dollars. In some areas, AI is being practiced in buffalo under different organizations (LAL Teer, BRAC), and the cost of AI was recorded as about BDT 600-700 or 5.68-6.63 US dollars per cow. The average daily milk yield was 3.0 liter, whereas the lactation length was recorded at 179.9±3.84 days. The major constraints were high feed price 91.66% (n=110), shortage of land 41.08% (n=51), and lack of suitable marketing facilities 50.82% (n=62). 100% of farmers stated that they need improved grass production technology and reduced feed and medicine price; 24.16% (n=29) need good quality semen. From 2004 to 2022, 51 studies were found related to buffalo, where the highest 27.45% (n=14) belonged to performance studies, and 54.90% (n=28) studies were carried out in the southern part of Bangladesh. Conclusion: It can be concluded that buffalo has great potential with different areas of improvement. Therefore, more research is needed from different perspectives on production, reproduction, nutrition, quality of milk/meat/products, health, and sustainability of buffalo farming in Bangladesh

An anatomical screening of white jute accessions for fibre content

The present study was conducted to evaluate the performance of 24 advanced lines of white jute and four check varieties ( CVL-1, CC-45, BJRI Deshi Pat-7 & BJRI Deshi Pat-8) for screening out high yielding and better quality fibre through an anatomical approach at JAES, Manikganj. The experiment was conducted in randomly complete block design (RCBD) with three replications. The cultivars revealed significant differences among them for all the characters with range of variability. The highest bark thickness (2.32 mm) was noticed by the accession C-5036 which performed significantly better than the two checks and lowest was recorded by C-5126 (1.07 mm). The variety BJRI Deshi Pat-8 observed significantly the highest number of pyramid (54.13) whereas the lowest was recorded by the varieties BJRI Deshi Pat-7 (28.23). The accession C-5117 showed significantly the highest number of layer (10.29) whereas the variety, BJRI Deshi Pat-7 showed significantly lowest number of layer (6.32). The accession C-2305(92.37) and C-12221 (91.19) significantly showed top two number of fibre bundle, however, the lowest number of fibre bundle was recorded by BJC-5105(42.79). The largest area of pyramid was observed by the accession C-5036 (46.85 sq. mm) whereas the lowest was showed by BJC-5105 (14.50 sq. mm). The differences between Phenotypic Coefficient of Variation (PCV) and Genotypic Coefficient of Variation (GCV) were little for all the characters indicating these characters were less influenced by the environment. Heritability and genetic advance (GA) were high for number of pyramid, number of fibre, bundle and Area of pyramid (sq.mm). Three accessions(C-12221, C-2305, C-5036) are showed the best performance than other accession on our screening program. These accessions are included in cluster V among the five clusters which exhibit the highest performance in all parameter except number of pyramid and may be used in further hybridization of jute

Determining Genetic Diversity of Deshi Jute (Corchorus capsularis) for the Improvement of Fibre Yield and Associated Traits

Commercially important natural fibres considered as fiber of the future are cultivated in different south-east Asian countries including India and Bangladesh. Unfortunately, they are characterized by limited genetic variation in terms of yield, quality and susceptibility to diseases and pests. Therefore, genetic deviation studies are crucial to develop a successful cultivation program to develop varieties to meet the growing demand for domestic and foreign jute products. In our study, which was conducted at the Central Jute Research Experiment Station of Bangladesh Jute Research Institute (BJRI), during Kharif seasons of 2014. 44 Thirteen progenies (1546, 1548, 4311, 4328, 4330, 4337, 4339, 5007, 6702/A, 6702/B, 6772, 6787, 6790) and two check varieties CVL-1 and CVE-3 (developed from Bangladesh Jute Research Institute) were investigated to study the genetic variability, genetic diversity and degree of association of different component characters related to fiber yield. The seeds of experimental plant materials were grown in Randomized Complete Block Design with three replications. Statistical analysis was run to find out the genotypic and phenotypic variances, correlations and cluster analysis for fibre yield related traits namely plant height (m), base diameter (cm), stick weight (g), fiber weight (g). Highly significant differences were observed among the genotypes for all the characters. Cluster analysis divided the accessions and varieties into four cluster. From our evaluation it was revealed that the treatment number 4337/06, 4339/06 and 6702/A performed better in most of the cases than the control varieties CVL-1 and CVE-3. These accessions may be used as parents for future variety development program

Growth and Yield of Hybrid Maize as Influenced by Fertilizer Management

An experiment was carried out at the Agronomy Field Laboratory, Department of Agronomy, Hajee Mohammad Danesh Science and Technology University, Bangladesh during the rabi season (December to May), 2012-13 to study the effect of different organic and inorganic fertilizers on growth and development of hybrid maize (Denali). The experiment was laid out in Randomized Complete block Design with three replications with 30 plots. Ten fertilizer treatments (T1= Compost, T2= Cow dung, T3= Poultry manure, T4= Recommended fertilizer dose, T5= Compost + Half recommended fertilizer dose, T6= Compost + Full recommended fertilizer dose, T7= Cow dung + Half recommended fertilizer dose, T8= Cow dung + Full recommended fertilizer dose, T9= Poultry manure + Half recommended fertilizer dose, T10= Poultry manure + Full recommended fertilizer dose. The recommended fertilizer dose was 500 Kg ha-1 urea + 250 Kg ha-1 TSP + 200 Kg ha-1 MP + 15 Kg ha-1 ZnSO4 + 6 Kg ha-1 Boric Acid. And the rate of Compost, Cow dung and Poultry manure was 10t/ha. The effect of different manure and fertilizer doses on the yield and yield attributes were significant. The plant height, number of leaves per plant, weight of stem per plant, weight of leaves per plant, length of cob, grain weight per cob, diameter of cob, no. of grains per row, no. of total grains per cob, 1000-grain weight, yield plant-1, yield ha-1 were significantly affected by different manures and fertilizer uses with different doses. The treatments T1, T2, T3, T4, T5, T6, T7, T8, T9 and T10 gave grain yield 10.16, 9.09, 8.49, 14.34, 13.35, 18.12, 11.99, 17.09, 11.40 and 15.98 t ha-1, respectively. The T6 Treatment gave higher grain yield (18.12) t ha-1 and the T3 treatment performed lowest grain yield (8.49 t ha-1). The application of compost and full dose fertilizer is higher yielding. Balance nutrition with enough organic matter enrichment of the soil is the cause of this result

Effect of Plant Growth Regulators on Fruit-set and Quality of Guava

Two plant growth regulators: β-NOA (50 and 80 ppm) and GA (200 and 250 ppm) were applied to emasculated flowers at anthesis to set parthenocarpic fruit, while in the control treatment fruit set was achieved by natural pollination. The application of β-NOA found ineffective in setting parthenocarpic guava. No significant differences were observed in the length and diameter of fruit between parthenocarpic and naturally pollinated seeded fruit at different days after anthesis. The mean fruit weight, TSS and ascorbic acid content of parthenocarpic fruit were similar to that of seeded fruit. Significant higher amount of total polyphenol was detected in the seeded fruit than the parthenocarpic fruit. Although 200 ppm GA showed comparatively better response to fruit growth, TSS and ascorbic acid content than 250 ppm GA but not in a statistical level

A Noble Proposal for Internet of Garbage Bins (IoGB)

Various technological devices have been developed to meet the ever-increasing demand of today’s cities. Cities, as we can see today, have become highly technology-oriented. However, technological advancement comes at a cost which in this case is the environment of our planet. Therefore, it is necessary to design green cities, which impose as less harm as it possibly can to the environment. One of the most important characteristics of these new cities is the way of managing their waste. Traditional waste management, which employs various sizes and shapes of trash cans at multiple places that are collected by hand after each use is space-consuming, manual, inefficient and often leads to environmental pollution. Therefore, we require a novel approach that is free from these constraints. This paper proposes a garbage management system integrating the fundamental ideas of smart waste management and ‘Internet of Things’ (IoT). The proposed system employs smart cyclic containers that rotate one by one after being filled with rubbish like ‘Merry Go Round’. This approach of waste management solves the problem of space-constraint in an innovative way. A central server monitors the whole system, which further dispatches an autonomous car to collect the waste when necessary. This IoT integrated waste management system is named ‘Internet of Garbage Bins’ (IoGB)

Morphometric features, seminal profile and diluters effect on post-thaw semen quality of Munshiganj cattle in Bangladesh

The study investigates morphometric features, seminal profile and post-thaw semen quality of Munshiganj cattle. Morphometric features were measured using measuring tape from 20 Munshiganj cattle while coat color was measured by observing in naked eye. Fresh and post thaw semen quality parameters were analyzed using Computer Assisted semen analyzer (CASA). Coat color of Munshiganj male cattle were creamy white to dull pinkish and female were white to creamy. The mean body weight, body length, hearth girth, height at wither, head length, head width, ear length, ear width, fore leg length, hind leg length, tail length, tail doc circumference, horn length, horn diameter and mouth circumference were 362.80 kg, 137.31 cm, 160.66 cm, 135.21 cm, 50.97 cm, 20.58 cm, 19.75 cm, 9.88 cm, 73.02 cm, 74.84 cm, 106.10 cm, 20.75 cm, 13.60 cm, 16.12 cm and 43.00 cm, respectively. There was significant difference (p  0.05) on post thaw semen quality except slow motility and proximal droplet percentages. Munshiganj cattle had a distinctive phenotypic feature with standard quality semen and had no effect of egg yolk free and egg yolk based diluters on post thaw semen quality