Experimental techniques for ductile damage characterisation

Ductile damage in metallic materials is caused by the nucleation, growth and coalesce of voids and micro-cracks in the metal matrix when it is subjected to plastic strain. A considerable number of models have been proposed to represent ductile failure focusing on the ultimate failure conditions; however, only some of them study in detail the whole damage accumulation process. The aim of this work is to review experimental techniques developed by various authors to measure the accumulation of ductile damage under tensile loads. The measurement methods reviewed include: stiffness degradation, indentation, microstructure analysis, ultrasonic waves propagation, X-ray tomography and electrical potential drop. Stiffness degradation and indentation techniques have been tested on stainless steel 304L hourglass-shaped samples. A special interest is placed in the Continuum Damage Mechanics approach (CDM) as its equations incorporate macroscopic parameters that can represent directly the damage accumulation measured in the experiments. The other main objective lies in identifying the strengths and weaknesses of each technique for the assessment of materials subjected to different strain-rate and temperature conditions

Analisis USAhatani dan Pemasaran Ubi Kayu dan Ubi Jalar di Simalungun (Studi Kasus: Desa Pematang Kerasaan Rejo Kecamatan Bandar dan Kelurahan Tiga Runggu Kecamatan Purba)

Penentuan daerah penelitian dilakukan secara purposive, simple random sampling. Metode analisis yang digunakan adalah analisis data deskriptif, fungsi produksi regresi berganda, uji beda rata-rata serta analisis BEP. Hasil penelitian menyimpulkan produktivitas ubi jalar di daerah penelitian lebih rendah dari produktivitas ubi jalar di Kabupaten Karo namun lebih tinggi dari produktivitas ubi jalar hasil penelitian BPTP Sumut. Produktivitas ubi kayu di daerah penelitian lebih tinggi dari produktivitas ubi kayu di Kabupaten Simalungun namun lebih rendah dari produktivitas ubi kayu hasil penelitian BPTP Sumut; Faktor produksi yang berpengaruh nyata terhadap produksi ubi jalar adalah penggunaan bibit dan herbisida sedangkan pada USAhatani ubi kayu, faktor produksi yang berpengaruh nyata adalah penggunaan bibit, herbisida dan TK; Tidak terdapat perbedaan rata-rata pendapatan USAhatani ubi jalar dengan pendapatan USAhatani ubi kayu dalam satu musim tanam; Jumlah produksi dan harga jual berpengaruh terhadap pendapatan USAhatani baik pada USAhatani ubi jalar maupun USAhatani ubi kayu; dan pemasaran ubi jalar di daerah penelitian belum efisien dan pemasaran ubi kayu di daerah penelitian belum efisien

Evaluation of environmental design strategies for university buildings

This paper examines the performance of environmental strategies in seven recently constructed or refurbished university buildings in the UK. These buildings contain a range of administrative spaces, classrooms, libraries and studios, reflecting their often complex, multi-use, heterogeneous nature. The key features of each environmental strategy are described (including passive, mixed-mode or active systems), in the context of the occupants and spaces they serve and the level of interaction that they afford. Energy performance and occupant thermal comfort (assessed by user surveys) are analysed and compared with studies of other non-domestic buildings, which have typically focused on more predictable single administrative uses (e.g. government offices), and unusually effective operation scenarios (e.g. continuous monitoring by expert building managers). The paper concludes by examining two of the case studies that reflect an increasingly common model of ‘flexible’ environmental design in more detail, identifying key features of the strategies for each building that have had a significant impact on their performance. The design assumptions leading to these features will be explored, and key lessons identified, contributing towards the development of a more robust evidential basis for choosing appropriate environmental strategies for university and other non-domestic buildings in the UK

An experimental methodology to characterise post-necking behaviour and quantify ductile damage accumulation in isotropic materials

The development of ductile damage, that occurs beyond the point of necking in a tensile test, can be difficult to quantify. An experimental methodology has been developed to accurately characterise the post-necking deformation response of a material through continuous monitoring of the specimens shape up until rupture. By studying the evolution of the neck geometry, the correct values of the local stress and strain have been determined in samples of grade 304L stainless steel and C110 copper. Notched bar specimens of various notch acuities were examined enabling the effects of stress triaxiality on ductile fracture to be determined. The methodology developed has provided a robust framework for macroscopic measurements of ductile damage during the necking process. To characterise the material degradation process, the elastic modulus reduction method was employed on hourglass-shaped specimens of the same materials. Stiffness degradation was measured using a small gauge extensometer during uninterrupted tensile tests with partial elastic unloadings. A metallographic study was conducted on progressively damaged specimens in order to validate the macroscopic damage measurements. A new non-linear ductile damage accumulation law has been developed and calibrated, which provides an advanced representation of the experimental results, and a significant improvement compared to linear accumulation models frequently employed. This realistic modelling approach considers the degradation of the material when it has undergone severe plastic deformation, and provides a more accurate representation of the near failure behaviour by considering the effects of stress triaxiality. The methodology provides accurate data for damage model development and calibration, to improve the predictions of remnant life from ductile damage in engineering components

Fluctuating awareness of treatment goals amongst patients and their caregivers: a longitudinal study of a dynamic process

Background: Because increasing numbers of people now survive for months or years with advanced cancer, communication between patients, service providers, and family caregivers often continues over long periods. Hence, understanding of the goals of medical treatment may develop and change as time elapses and disease progresses. This understanding is closely related to the "awareness of dying," which has been studied in both qualitative and quantitative research. However, when both a patient and family caregiver are involved, the question of "awareness" becomes more complex. A recent longitudinal study reported on patient and caregiver knowledge of treatment goals, but no comparison of such knowledge using matched interview schedules and paired data analysis has been provided. This report examines patterns of awareness and factors associated with these patterns. Materials and methods: One hundred sixty-three patients with incurable cancer and their nominated principal family caregivers (136) were recruited from The Canberra Hospital Oncology Services. Participants' understanding of the treatment goals were measured by interview questions at weeks 1 and 12. Results: One-third of both patients and caregivers understood that the treatment goal was not curative; however, not all patient and caregiver pairs had the same understanding. In 15% of pairs, both patient and caregiver believed that the goal of treatment was curative, while another 13% said that they did not know the aim of the treatment. Thirty-nine percent of pairs registered incongruent responses in which only one member of the pair understood that the treatment was not intended to cure the disease. Over time, a few respondents changed their perception of the treatment goals toward accurate clarification. Bivariate analysis using an awareness variable, constructed for the purpose, showed that in 6 months before death, at least one person in 89% of pairs understood that the treatment was noncurative. Time-to-death, gender, and place of residence were also important predictors of knowledge. Conclusions: Discrepancies between patients and their caregivers may complicate the delivery of effective care when patients are seriously ill. Misunderstanding or uncertainty about treatment goals will obstruct proper informed consent. Health professionals providing care for families dealing with advanced cancer must recognize that the discussion of treatment goals is a dynamic process, which may require them to extend their communication skills

Imperialist Competitive Algorithm with Independence and Constrained Assimilation for Solving 0-1 Multidimensional Knapsack Problem

The multidimensional knapsack problem is a well-known constrained optimization problem with many real-world engineering applications. In order to solve this NP-hard problem, a new modified Imperialist Competitive Algorithm with Constrained Assimilation (ICAwICA) is presented. The proposed algorithm introduces the concept of colony independence, a free will to choose between classical ICA assimilation to empires imperialist or any other imperialist in the population. Furthermore, a constrained assimilation process has been implemented that combines classical ICA assimilation and revolution operators, while maintaining population diversity. This work investigates the performance of the proposed algorithm across 101 Multidimensional Knapsack Problem (MKP) benchmark instances. Experimental results show that the algorithm is able to obtain an optimal solution in all small instances and presents very competitive results for large MKP instances

no Routing Needed Between Capsules

Copyright © 2021 The Authors. Most capsule network designs rely on traditional matrix multiplication between capsule layers and computationally expensive routing mechanisms to deal with the capsule dimensional entanglement that the matrix multiplication introduces. By using Homogeneous Vector Capsules (HVCs), which use element-wise multiplication rather than matrix multiplication, the dimensions of the capsules remain unentangled. In this work, we study HVCs as applied to the highly structured MNIST dataset in order to produce a direct comparison to the capsule research direction of Geoffrey Hinton, et al. In our study, we show that a simple convolutional neural network using HVCs performs as well as the prior best performing capsule network on MNIST using 5.5× fewer parameters, 4× fewer training epochs, no reconstruction sub-network, and requiring no routing mechanism. The addition of multiple classification branches to the network establishes a new state of the art for the MNIST dataset with an accuracy of 99.87% for an ensemble of these models, as well as establishing a new state of the art for a single model (99.83% accurate)

Imperialist Competitive Algorithm with Independence and Constrained Assimilation

Autonomous Supply Chai