Prediction by a Genetic Algorithm of the Fiber-Matrix Interface Damage for Composite Material. Part 1. Study of Shear Damage in Two Composites T300/914 and PEEK/APC2

We have conducted research on the effect of fiber arrangement on the optimization of the damage to the interface, recently published. We develop in this paper the evolution of the damage in the shearing direction by genetic algorithm. The results obtained by varying the shear rate of the interface of the two materials studied T300 and PEEK, show a good agreement between our genetic approach and the mathematical models presented by Cox and Weibull.Для композитных материалов, армированных волокнами, актуальной является оптимизация размещения последних, что обеспечивает минимальное повреждение на стыке волокон и матрицы. Исследована кинетика развития повреждений в направлении действия максимальных сдвиговых напряжений с помощью генетического алгоритма, ранее разработанного авторами. Для двух композитов типа T300 и PEEK с использованием предложенного генетического подхода получены расчетные данные для различных скоростей сдвиговых деформаций на стыке волокон и матрицы, которые хорошо согласуются с полученными на основании математических моделей Кокса и Вейбулла. В дальнейших исследованиях планируется изучение влияния термомеханического нагружения на сдвиговое повреждение зоны стыка волокон и матрицы.Для композитних матеріалів, армованих волокнами, актуальною є оптимізація розміщення останніх, що забезпечує мінімальне пошкодження на стику волокон і матриці. Досліджено кінетику розвитку пошкоджень у напрямку дії максимальних зсувних напружень за допомогою раніше розробленого авторами генетичного алгоритму. Для двох композитів типу Т300 і PEEK з використанням запропонованого генетичного підходу отримано розрахункові дані для різної швидкості зсувних деформацій на стику волокон і матриці, які добре узгоджуються з отриманими на основі математичних моделей Кокса і Вейбулла. У подальших дослідженнях планується вивчення впливу термомеханічного навантаження на зсувне пошкодження зони стику волокон і матриці

Business and Information Technology Alignment Measurement -- a recent Literature Review

Since technology has been involved in the business context, Business and Information Technology Alignment (BITA) has been one of the main concerns of IT and Business executives and directors due to its importance to overall company performance, especially today in the age of digital transformation. Several models and frameworks have been developed for BITA implementation and for measuring their level of success, each one with a different approach to this desired state. The BITA measurement is one of the main decision-making tools in the strategic domain of companies. In general, the classical-internal alignment is the most measured domain and the external environment evolution alignment is the least measured. This literature review aims to characterize and analyze current research on BITA measurement with a comprehensive view of the works published over the last 15 years to identify potential gaps and future areas of research in the field.Comment: 12 pages, Preprint version, BIS 2018 International Workshops, Berlin, Germany, July 18 to 20, 2018, Revised Paper

Surgical management of Diabetic foot ulcers: A Tanzanian university teaching hospital experience

\ud \ud Diabetic foot ulcers (DFUs) pose a therapeutic challenge to surgeons, especially in developing countries where health care resources are limited and the vast majority of patients present to health facilities late with advanced foot ulcers. A prospective descriptive study was done at Bugando Medical Centre from February 2008 to January 2010 to describe our experience in the surgical management of DFUs in our local environment and compare with what is known in the literature. Of the total 4238 diabetic patients seen at BMC during the period under study, 136 (3.2%) patients had DFUs. Males outnumbered females by the ratio of 1.2:1. Their mean age was 54.32 years (ranged 21-72years). Thirty-eight (27.9%) patients were newly diagnosed diabetic patients. The majority of patients (95.5%) had type 2 diabetes mellitus. The mean duration of diabetes was 8.2 years while the duration of DFUs was 18.34 weeks. Fourteen (10.3%) patients had previous history of foot ulcers and six (4.4%) patients had previous amputations. The forefoot was commonly affected in 60.3% of cases. Neuropathic ulcers were the most common type of DFUs in 57.4% of cases. Wagner's stage 4 and 5 ulcers were the most prevalent at 29.4% and 23.5% respectively. The majority of patients (72.1%) were treated surgically. Lower limb amputation was the most common surgical procedure performed in 56.7% of cases. The complication rate was (33.5%) and surgical site infection was the most common complication (18.8%). Bacterial profile revealed polymicrobial pattern and Staphylococcus aureus was the most frequent microorganism isolated. All the microorganisms isolated showed high resistance to commonly used antibiotics except for Meropenem and imipenem, which were 100% sensitive each respectively. The mean hospital stay was 36.24 ± 12.62 days (ranged 18-128 days). Mortality rate was 13.2%. Diabetic foot ulceration constitutes a major source of morbidity and mortality among patients with diabetes mellitus at Bugando Medical Centre and is the leading cause of non-traumatic lower limb amputation. A multidisciplinary team approach targeting at good glycaemic control, education on foot care and appropriate footware, control of infection and early surgical intervention is required in order to reduce the morbidity and mortality associated with DFUs. Due to polymicrobial infection and antibiotic resistance, surgical intervention must be concerned

Half‐metallic ferromagnetic properties of Cr‐ and V‐doped AlP semiconductors

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A Novel Theoretical Study of Elastic and Electronic Properties of M₂CdC (M = Zr, Hf, and Ta) MAX Phases

In this study, we have investigated the structural, electronic, and elastic properties of the M₂CdC (M = Ta, Zr, and Hf) MAX phases, using the first-principle methods based on the density functional theory. The calculated formation energies revealed that these compounds are thermodynamically stable in the hexagonal MAX phase. The stability is confirmed by the elastic constants and the conditions of mechanical stability criterion. Also, we have determined the bulk and shear modules of the Young modulus and the Poisson coefficient. The band structures indicate that the three materials are electrically conductive. The chemical bond in M₂CdC is covalent-ionic in nature with the presence of metallic character. For the density of states the hybridization peak between M d and C p occurs in the lower energy range. We have found that there is no gap for these materials due to the existence of a maximum peak of DOS around Fermi level

Theoretical Predictions of Electronic Structure and Half‐Metallic Ferromagnetism in Al1−x Mn x P Diluted Magnetic Semiconductors

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Theoretical investigation of the performance of nonlinear optical properties in Push-pull chromophores derivatives of acrylo-azobenzene

International audienceDue to their strong molecular hyperpolarizability, organic push–pull materials are gaining interest for nonlinear optical applications. We were able to characterize the intramolecular charge transfer and the distribution of the electron cloud within the molecular unit by exciting these materials under the influence of an electric field. The series products of conjugated monomers derived from acrylo–azobenzene containing in the para position the attracting groups (–H, –NO2, –COOC2H5, –SO3H and –COOH) exhibit good nonlinear optical activity. We computed the nonlinear optical characteristics of these compounds as well as exploiting the theoretical calculations of DFT and AM1 to determine their hyperpolarizabilities. Besides, we investigated the increase in hyperpolarizability in the push–pull model of organic compounds under the effect of the strength of attracting groups, the existence of the conjugated π-electron and the azo bridge

Efekt naturalnych włókien Alfa na poprawę mechanicznych właściwości materiałów kompozytowych z matrycą epoksydową badany za pomocą algorytmu genetycznego

Natural fibres have a very important role in improving the mechanical properties of composite materials. Our objective in this study was to use alfa natural fibre in a composite material based essentially on epoxy matrix and calculate the interface fibre-matrix damage of carbon-epoxy, glass-epoxy and alfa-epoxy. Each sample was reinforced with the same volume fraction before being subjected to various mechanical tests. The results found by genetic simulation showed that the level of damage to the alfa-epoxy material was lower compared to other composite materials studied. We can say that alfa natural fibre has a high resistance to the mechanical stress applied; but the question remains whether the new material has the same resistance to thermal stress.Włókna naturalne spełniają bardzo ważną rolę przy polepszeniu właściwości mechanicznych materiałów kompozytowych. Celem badań w przedstawionej pracy było zastosowanie naturalnych włókien alfa dla wzmocnienia mechanicznych właściwości materiałów kompozytowych z matrycą epoksydową. Określano zniszczenie międzyfazowych układów włókna węglowe-epoksyd, włókna szklane-epoksyd i włókna alfa-epoksyd. Każda badana próbka była wzmacniana tym samym objętościowym udziałem poszczególnych rodzajów włókien. Wyniki badań określone przy stosowaniu symulacji genetycznej pokazały, że poziom zniszczenia układów fazowych alfa-matryca epoksydowa był niższy w porównaniu do innych badanych materiałów kompozytowych. Na podstawie przeprowadzonych badań można stwierdzić, że naturalne włókna alfa posiadają wysoką odporność na przyłożone naprężenia mechaniczne. Zagadnieniem nierozwiązanym pozostaje czy włókna naturalne alfa posiadają dobrą odporność na działanie temperatury

First principles study of the electronic structures and magnetic properties of transition metal‐doped cubic indium nitride

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