Degradation and Fatigue Involving Dissipated Processes

Irreversible material degradation due to cyclic mechanical loading is investigated utilizing the concept of thermodynamic entropy, plastic strain energy, and temperature slope measurement. Uniaxial tension-compression and fully-reversed bending fatigue tests are performed over a wide range of loading conditions with metallic and composite materials subject to both constant- and variable-amplitude loading. A methodology is developed for the estimation of the fatigue fracture entropy (FFE) and fatigue toughness of metallic specimens in a rapid fashion. It is found that the FFE and the fatigue toughness of each material tested are within a small band. The value of FFE is found to be unique for a given type of a material, substantiating that FFE can be regarded as a material property. The concept of FFE is applied to study the effect of stress concentration on a metallic specimen. It is found that the FFE of a V-notched specimen with certain amount of stress concentration is fairly constant. A formula is derived for the prediction of the fatigue life of a V-notched specimen based on the fatigue test results of an un-notched specimen. The concept of FFE is utilized to study the high-cycle fatigue (HCF) of carbon steel 1018. As the stress levels in HCF are substantially smaller than the yield strength of the material, a considerable amount of anelastic energy is present in the hysteresis loop along with plastic strain energy. We propose a method to calculate anelastic energy so that entropy generation can be estimated. Finite element simulations are performed to validate the assumptions made in the development of the methodology. It is found that the FFE of this material remains within a specific band both for the low- and high-cycle fatigue. A methodology is developed for the prediction of the remaining fatigue life (RFL) of a specimen with prior history of loading in a non-destructive (NDT) fashion based on the slope of temperature rise obtained from the specimen under cyclic loading. This method which uses thermographic technique has been validated with API 5L X52, carbon steel 1018, and Glass/Epoxy composite with promising results. This approach is further extended to derive a correlation between the damage parameter and the temperature slope obtained from a fatigued specimen. This correlation and the so-called master curve of damage evolution are employed to develop a methodology for the prediction of the RFL of a metallic specimen

A Vector Error Correction Model of Australian Coking Coal Exports

This article examines the long-run equilibrium relationships between the Australian coking coal export and selected variables. Upon testing with appropriate co-integration and vector error-correction models, we detected that the exchange rate of A$/US$, Australian coking coal price and world supply of coking coal have a negative impact on Australian coking coal export in the long run as well as the short run. On the other hand, world demand for coking coal and USA coking coal prices have positive relationships with the Australian coking coal export in the long run and short run. All of these relationships are statistically significant at the 1% level

Influence Of Australian Coal Export On A/US/US Exchange Rate: A Longitudinal Study

This paper investigates the contribution of Australian coal export to determine the exchange rate of Australian dollar with the US dollar. The quarterly data of Australian coal export and the Australian dollar exchange rate from 1992-2009 are employed to measure the influence of Australian coal export on A$/US$ exchange rate. This study finds that the Australian coal export has a positive relationship with the exchange rate of A$/US$ and their relationship is becoming stronger. The findings of this research suggest that the volume of Australian coal export contributes about 8% to determine the exchange rate of A$/US$ between the period of 1992-2009.  The results of this analysis confirm that for each one million tonnes export increase of Australian coal, the Australian dollar value against the US$ increases by 0.002450 USD

Patient Satisfaction in Chamber Setting in Bangladesh measured by Patient-Doctor Relationship Questionnaire (PDRQ-9 Bangla)

Background: Assessment of patient satisfaction is crucial but there is significant lagging in this sector. Patient satisfaction is an important indicator of health care quality as well as a predictor of treatment adherence. The Good patient-doctor relationship is considered as an integral part of the patient satisfaction. In Bangladesh, this domain is yet to be explored in a large scale. Aim: It was aimed to look into the patient satisfaction level in chamber setting in Bangladesh measured using the patient-doctor relationship questionnaire (PDRQ-9 Bangla). Methods: PDRQ-9 is a short yet excellent tool for assessing the patient-doctor relationship. The data collection was done in private chamber setting by the PDRQ-9 and analyzed. Results: Though the result was not completely in line with the existing literature, the PDRQ-9 was found to be a useful and brief measurement tool in the context of the patient-doctor relationship. Conclusion: Large-scale research in this particular aspect of patient satisfaction in future may provide a more succinct resul

Genomic Diversity and Introgression in O. sativa Reveal the Impact of Domestication and Breeding on the Rice Genome

The domestication of Asian rice (Oryza sativa) was a complex process punctuated by episodes of introgressive hybridization among and between subpopulations. Deep genetic divergence between the two main varietal groups (Indica and Japonica) suggests domestication from at least two distinct wild populations. However, genetic uniformity surrounding key domestication genes across divergent subpopulations suggests cultural exchange of genetic material among ancient farmers.In this study, we utilize a novel 1,536 SNP panel genotyped across 395 diverse accessions of O. sativa to study genome-wide patterns of polymorphism, to characterize population structure, and to infer the introgression history of domesticated Asian rice. Our population structure analyses support the existence of five major subpopulations (indica, aus, tropical japonica, temperate japonica and GroupV) consistent with previous analyses. Our introgression analysis shows that most accessions exhibit some degree of admixture, with many individuals within a population sharing the same introgressed segment due to artificial selection. Admixture mapping and association analysis of amylose content and grain length illustrate the potential for dissecting the genetic basis of complex traits in domesticated plant populations.Genes in these regions control a myriad of traits including plant stature, blast resistance, and amylose content. These analyses highlight the power of population genomics in agricultural systems to identify functionally important regions of the genome and to decipher the role of human-directed breeding in refashioning the genomes of a domesticated species

Impact on bus superstructure due to rollover

Bus is a popular and common transport in the world. The safety of bus journey is a fundamental concern. The risk of injuries and fatalities is severe when the bus structure fails during a rollover accident. Adequate design and sufficient strength of the bus superstructure can reduce the number of injuries and fatalities. This study examines the deformation response of a typical bus structure during a rollover test simulation. A simplified box structure was modeled using finite element analysis software and simulated in a rollover condition according to the requirements of UNECE Regulation 66. The same box model was fabricated to validate the results obtained from finite element analysis simulation. After successful validation of the box model simulation, a complete bus structure with forty four passengers’ capability was developed using finite element analysis software. The simulation of the bus was conducted using the same inputs used in box model simulation. Four simulations have been conducted to get the dimensions of different members of the superstructure of bus which is capable to protect rollover crash. The analysis suggested that, the failure of bus frame during rollover situation is basically dependent on the total mass of bus and on the strength of bus superstructure

Security Threats in Mobile Ad Hoc Network

Mobile Ad Hoc Network (MANET) is a collection of communication devices or nodes that wish to communicate without any fixed infrastructure and pre-determined organization of available links. The nodes in MANET themselves are responsible for dynamically discovering other nodes to communicate. Although the ongoing trend is to adopt ad hoc networks for commercial uses due to their certain unique properties, the main challenge is the vulnerability to security attacks. A number of challenges like open peer-to-peer network architecture, stringent resource constraints, shared wireless medium, dynamic network topology etc. are posed in MANET. As MANET is quickly spreading for the property of its capability in forming temporary network without the aid of any established infrastructure or centralized administration, security challenges has become a primary concern to provide secure communication. In this thesis, we identify the existent security threats an ad hoc network faces, the security services required to be achieved and the countermeasures for attacks in each layer. To accomplish our goal, we have done literature survey in gathering information related to various types of attacks and solutions, as well as we have made comparative study to address the threats in different layers. Finally, we have identified the challenges and proposed solutions to overcome them. In our study, we have found that necessity of secure routing protocol is still a burning question. There is no general algorithm that suits well against the most commonly known attacks such as wormhole, rushing attack etc. In conclusion, we focus on the findings and future works which may be interesting for the researchers like robust key management, trust based systems, data security in different layer etc. However, in short, we can say that the complete security solution requires the prevention, detection and reaction mechanisms applied in MANET

Security Threats in Mobile Ad Hoc Network

Mobile Ad Hoc Network (MANET) is a collection of communication devices or nodes that wish to communicate without any fixed infrastructure and pre-determined organization of available links. The nodes in MANET themselves are responsible for dynamically discovering other nodes to communicate. Although the ongoing trend is to adopt ad hoc networks for commercial uses due to their certain unique properties, the main challenge is the vulnerability to security attacks. A number of challenges like open peer-to-peer network architecture, stringent resource constraints, shared wireless medium, dynamic network topology etc. are posed in MANET. As MANET is quickly spreading for the property of its capability in forming temporary network without the aid of any established infrastructure or centralized administration, security challenges has become a primary concern to provide secure communication. In this thesis, we identify the existent security threats an ad hoc network faces, the security services required to be achieved and the countermeasures for attacks in each layer. To accomplish our goal, we have done literature survey in gathering information related to various types of attacks and solutions, as well as we have made comparative study to address the threats in different layers. Finally, we have identified the challenges and proposed solutions to overcome them. In our study, we have found that necessity of secure routing protocol is still a burning question. There is no general algorithm that suits well against the most commonly known attacks such as wormhole, rushing attack etc. In conclusion, we focus on the findings and future works which may be interesting for the researchers like robust key management, trust based systems, data security in different layer etc. However, in short, we can say that the complete security solution requires the prevention, detection and reaction mechanisms applied in MANET

Investigation of directional and functional relationships of Australian dollar exchange rate, steam coal export and steam coal price

The interesting finding in this paper is that the Australian coal exporters loss which occurs due to a strong A$is less than the profit from increasingly higher prices of Australian steam coal and for this reason, Australian steam coal exporters choose to export more when the price is high. The empirical results of this analysis confirm that for each one cent increase in Australian dollar value against the US$, the Australian steam coal price increases by 0.8182 US$and additional each one million tonnes export of Australian steam coal, the Australian steam coal price increases by 1.752 US$