Reavling of Failure Modes in FRP Composites

Fibre-reinforced composite materials are used extensively in stiffness critical, weight sensitive structures such as those found in aerospace and motor racing where strength to weight ratio is very much important. They are characterized by high in-plane strength, stiffness and toughness and low density. The environmental effect on the FRP (fibre reinforced polymer) and the subsequent failure has lead to emphasize on the study of different fracture surfaces. The presence of moisture and the stresses associated with the moisture induced expansion may cause lowering of damage tolerance and structural durability. In case of water absorption there are both reversible and irreversible changes in the mechanical properties of the thermoset polymers. Delamination between layers is an important problem in applications of fiber reinforced composite laminates. This paper is an attempt to study the surfaces that have failed and to reveal the failure mechanism that has occurred using microscopic techniques. By observing carefully the fracture surface of the composite, the factors affecting their respective failure and the type of environment they were subjected to could be determined. SEM micrographs of the fractured surfaces of glass/epoxy and jute/epoxy composites under various environmental conditions were studied revealing the failure modes (delamination sites, debonding, fiber pullout regions, crack propagation front, striations and bubble bursting in the matrix). AFM micro graphs were studied to give a precise outlook of the behavior of composites to the changing environmental conditions being exposed to such as moisture absorption etc

Lichen Planus-like Eruption Resulting from a Jellyfish Sting

Introduction: Contact with a jellyfish can cause a wide variety of conditions, ranging from cutaneous eruption to fatal cardiovascular and respiratory collapse. Cutaneous features can be both acute and chronic. We report a case of persistent lichen planus-like eruption in a young boy after a jellyfish sting, a hitherto unreported occurrence. Case presentation: A 15-year-old boy presented with multiple lichen planus-like violaceous papules over the lower part of his left thigh on the anterior aspect and also over the patellar region. He had a history of a jellyfish sting over his lower limbs incurred while bathing in the sea 4 weeks prior to presentation. Histopathology revealed a predominantly perivascular mononuclear cell infiltrate immediately beneath the dermoepidermal junction underneath the hyperplastic epidermis. The lesions significantly subsided with topical corticosteroid application. Conclusion: This case report demonstrates a new variant of chronic cutaneous change following a jellyfish sting. We report it because of its uniqueness and we believe that physicians should be aware of the possibility of an aquatic animal-induced disease when dealing with lesions with lichen planus-like morphology.&nbsp

Lichen planus-like eruption resulting from a jellyfish sting: a case report

<p>Abstract</p> <p>Introduction</p> <p>Contact with a jellyfish can cause a wide variety of conditions, ranging from cutaneous eruption to fatal cardiovascular and respiratory collapse. Cutaneous features can be both acute and chronic. We report a case of persistent lichen planus-like eruption in a young boy after a jellyfish sting, a hitherto unreported occurrence.</p> <p>Case presentation</p> <p>A 15-year-old boy presented with multiple lichen planus-like violaceous papules over the lower part of his left thigh on the anterior aspect and also over the patellar region. He had a history of a jellyfish sting over his lower limbs incurred while bathing in the sea four weeks prior to presentation. Histopathology revealed a predominantly perivascular mononuclear cell infiltrate immediately beneath the dermoepidermal junction underneath the hyperplastic epidermis. The lesions significantly subsided with topical corticosteroid application.</p> <p>Conclusion</p> <p>This case report demonstrates a new variant of chronic cutaneous change following a jellyfish sting. We report it because of its uniqueness and we believe that physicians should be aware of the possibility of an aquatic animal-induced disease when dealing with lesions with lichen planus-like morphology.</p

Nanofabrication for Molecular Scale Devices

The predicted 22-nm barrier which is seemingly going to put a final stop to Moore’s law is essentially related to the resolution limit of lithography. Consequently, finding suitable methods for fabricating and patterning nanodevices is the true challenge of tomorrow’s electronics. However, the pure matter of moulding devices and interconnections is interwoven with research on new materials, as well as architectural and computational paradigms. In fact, while the performance of any fabrication process is obviously related to the characteristic of the materials used, a particular fabrication technique can put constraints on the definable geometries and interconnection patterns, thus somehow biasing the upper levels of the computing machine. Further, novel technologies will have to account for heat dissipation, a particularly tricky problem at the nanoscale, which could in fact prevent the most performing nanodevice from being practically employed in complex networks. Finally, production costs – exponentially growing in the present Moore rush – will be a key factor in evaluating the feasibility of tomorrow technologies. The possible approaches to nanofabrication are commonly classified into top-down and bottom-up. The former involves carving small features into a suitable bulk material; in the latter, small objects assemble to form more complex and articulated structures. While the present technology of silicon has a chiefly top-down approach, bottom-up approaches are typical of the nanoscale world, being directly inspired by nature where molecules are assembled into supramolecular structures, up to tissues and organs. As top-down approaches are resolution-limited, boosting bottom-up approaches seems to be a good strategy to future nanoelectronics; however, it is highly unlikely that no patterning will be required at all, since even with molecular-scale technologies there is the need of electrically contacting the single elements and this most often happens through patterned metal contacts, although all-molecular devices were also proposed. Here, we will give some insight into both top-down and bottom-up without the intention to be exhaustive, because of space limitations

Pre-emptive Dynamic Source Routing: A Repaired Backup Approach and Stability Based DSR with Multiple Routes

DSR algorithm finds out the best path for communicating between two nodes in a highly dynamic environment. Since, the environment changes frequently, the probability of established path breakage is also high. Again, as the breakage possibility increases, a new route has to be discovered every time .In order to avoid path discovery every time, we propose the modification of the existing DSR algorithm. In this paper we propose an enhancement of the DSR protocol based on a backup route(second best route) which will be provided by the destination node to the source node along with the best route during the process of path discovery. During the path maintenance process, in case any intermediate node identifies that the signal strength falls below a threshold i.e. the established route is about to break, the intermediate node sends a caution message to the source node. The source node switches the communication through the backup path , apprehending that the established route is about to break. As the communication through the backup route takes place, the previous route is repaired, if possible and acts as the new backup route. This process of toggling between backup route and established route reduces the call for path discovery to some extent. The stability in consideration of failure of common link and nodes in the back up repaired algorithm has been investigated with new algorithm for stable route selection

Neuro Symbolic Reasoning for Planning: Counterexample Guided Inductive Synthesis using Large Language Models and Satisfiability Solving

Generative large language models (LLMs) with instruct training such as GPT-4 can follow human-provided instruction prompts and generate human-like responses to these prompts. Apart from natural language responses, they have also been found to be effective at generating formal artifacts such as code, plans, and logical specifications from natural language prompts. Despite their remarkably improved accuracy, these models are still known to produce factually incorrect or contextually inappropriate results despite their syntactic coherence - a phenomenon often referred to as hallucination. This limitation makes it difficult to use these models to synthesize formal artifacts that are used in safety-critical applications. Unlike tasks such as text summarization and question-answering, bugs in code, plan, and other formal artifacts produced by LLMs can be catastrophic. We posit that we can use the satisfiability modulo theory (SMT) solvers as deductive reasoning engines to analyze the generated solutions from the LLMs, produce counterexamples when the solutions are incorrect, and provide that feedback to the LLMs exploiting the dialog capability of instruct-trained LLMs. This interaction between inductive LLMs and deductive SMT solvers can iteratively steer the LLM to generate the correct response. In our experiments, we use planning over the domain of blocks as our synthesis task for evaluating our approach. We use GPT-4, GPT3.5 Turbo, Davinci, Curie, Babbage, and Ada as the LLMs and Z3 as the SMT solver. Our method allows the user to communicate the planning problem in natural language; even the formulation of queries to SMT solvers is automatically generated from natural language. Thus, the proposed technique can enable non-expert users to describe their problems in natural language, and the combination of LLMs and SMT solvers can produce provably correct solutions.Comment: 25 pages, 7 figure

Exploring V-Fe-Co-Ni-Al and V-Fe-Co-Ni-Cu high entropy alloys for magnetocaloric applications

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