A mathematically simple method based on definition for computing eigenvalues, generalized eigenvalues and quadratic eigenvalues of matrices

Abstract.In this paper, a fundamentally new method, based on the definition, is introduced for numerical computation of eigenvalues, generalized eigenvalues and quadratic eigenvalues of matrices. Some examples are provided to show the accuracy and reliability of the proposed method. It is shown that the proposed method gives other sequences than that of existing methods but they still are convergent to the desired eigenvalues, generalized eigenvalues and quadratic eigenvalues of matrices. These examples show an interesting phenomenon in the procedure: The diagonal matrix that converges to eigenvalues gives them in decreasing order in the sense of absolute value. Appendices A to C provide Matlab codes that implement the proposed algorithms. They show that the proposed algorithms are very easy to program

Adsorption of Escherichia coli Using Bone Char

The aim of study was providing a novel adsorbent for the removal of Escherichia coli (E.coli) as a microbial model from contaminated air especially in hospital units using bone char (BC). The BC was prepared from cattle animal bone by pyrolysis in a furnace at 450°C for 2 h. The characteristics of BC have been determined using scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), pHzpc, apparent density and iodine number. Nebulizer system applied to convert the E.coli with different concentration into bioaerosols. The variables included: BC weights (4-10 g), the adsorbent pore size (20-40 mesh) and microbial concentrations (103-107 CFU/mL). Characteristics of the adsorbent show the ability of the BC to remove E.coli fromair. The results shows the higher amounts of BC, the more efficiency achieved to purify contaminate air and particles in the range of 20-40 mesh were more practical in removing bioaerosols. An efficient time for removing the more E.coli was 30 minutes. The maximum bacterial efficiency removal achieved was 99.99%. Comparison of removalefficiency with other literature showed that the BC particles were better mineral sorbents than other organic adsorbents and a commercial activated carbon. In this study, we investigated a novel air purification adsorbent and the information obtained in the paper is of fundamental significance for the mineral adsorbents especially bone charin cleaning of indoor bioaeroso

Development of an oxide-dispersion-strengthened steel by introducing oxygen carrier compound into the melt aided by a general thermodynamic model

In general, melting process is not a common method for the production of oxide dispersion strengthened (ODS) alloys due to agglomeration and coarsening of oxide particles. However, vacuum casting process has recently been employed as a promising process to produce micro-scale oxide dispersed alloys. In this paper, we report the process and characterization of in situ formation and uniform dispersion of nano-scale Y-Ti oxide particles in Fe-10Ni-7Mn (wt.%) alloy. The processing route involves a solid-liquid reaction between the added TiO2 as an oxygen carrier and dissolved yttrium in liquid metal leading to an optimal microstructure with nano-sized dispersed oxide particles. The developed thermodynamic model shows the independence of the final phase constituents from experimental conditions such as melting temperature or vacuum system pressure which offers a general pathway for the manufacture of oxide dispersion strengthened materials.1131Ysciescopu

In situ nanoindentation: probing nanoscale multifunctionality

Nanoindentation is the leading technique for evaluating nanoscale mechanical properties of materials. Consistent developments in instrumentation and their capabilities are transforming nanoindentation into a powerful tool for characterization of multifunctionality at the nanoscale. This review outlines the integration of nanoindentation with real-time electron imaging, high temperature measurements, electrical characterization, and a combination of these. In situ nanoindentation measurements have enabled the real-time study of the interplay between mechanical, thermal, and electrical effects at the nanoscale. This review identifies previous reviews in this area, traces developments and pinpoints significant recent advances (post-2007), with emphasis on the applications of in situ nanoindentation techniques to materials systems, and highlighting the new insights gained from these in situ techniques. Based on this review, future directions and applications of in situ nanoindentation are identified, which highlight the potential of this suite of techniques for materials scientists from all disciplines

Three-Dimensional Design of Axial Flow Compressor Blades Using the Ball-Spine Algorithm

Recently a new inverse design algorithm has been developed for the design of ducts, called ball-spine (BS). In the BS algorithm, the duct walls are considered as a set of virtual balls that can freely move along some specified directions, called ‘spines’. Initial geometry is guessed and the flow field is analyzed by a flow solver. Comparing the computed pressure distribution (CPD) with the target pressure distribution (TPD), new balls positions for the modified geometry are determined. This procedure is repeated until the target pressure is achieved. In the present work, the ball-spine algorithm is applied to three-dimensional design of axial compressor blades. The design procedure is tested on blades based on NACA65-410 and NACA65-610 profiles and the accuracy of the method is shown to be very good. As an application, the pressure distribution of the blade with NACA65-610 profiles is modified and the pressure gradient in the aft part of the blade is decreased and selected as target pressure distribution. The corresponding geometry which satisfies the target pressure is determined using the BS design algorithm

Explaining the goals of the curriculum based on teacher-researcher training at Farhangian University

Background and Objectives: The purpose of architecture education is to prepare graduates for general proficiency in this field of study. However, many graduates of architecture who are employed at the job market observe a profound gap between what they have learned in college and what is being done in professional work in architecture. This study -by examining the method of architecture education at undergraduate level and the job market situation in Iran- evaluates the relationship between the education and professional work in architecture to answer the following questions: "1. What are the problems of undergraduate architecture education in Iran that cause the inefficiency of architecture graduates in professional environment?", "2. Which features in the professional environment are necessary for a graduate of architecture?" and "3. How can we make a more effective connection between and the professional architectural environment?" Methods: The present study is an applied one and its method is field survey. In addition, the method of data analysis is analytical-descriptive. Data collection has been done through handing questionnaires and holding interviews with senior undergraduate architecture students as the statistical population who are supposed to enter the architectural job market soon, professors of architecture schools as individuals who are teaching students in this field, and professional architects as individuals who are professionally active in the field of architecture. The students and professors who were studied in this research were selected from 3 Iranian universities at the intermediate level, and professional architects were also selected from the managers of architectural companies. Being a veteran architect was the criterion for selecting professors and architects. The criteria for professors to be a veteran architect have been the experience and years of work, and the academic degree. The criteria for selecting architects have been experience and years of work, the significant number of the projects implemented, and winning awards. Findings: According to the common viewpoints of the three groups who were investigated in this research, the problems of the architecture educational environment that have created a gap between architecture education and architectural profession and the low efficiency of the architecture graduate in the professional environment have a wide range from the beginning of admission of architecture students up to after their graduation. The main problems are: 1. Method of student admission, 2. Admission of too many students, 3. Incompatibility of educational topics with the job market needs, 4. The separation of university from the society, 5. Lack of professional ethics training, 6. Lack of interactive skills training, 7. Lack of professional experience of professors, and 8. General problems of the society including economic issues. Therefore, the characteristics that are necessary for a graduate student of architecture in a professional environment are: 1. Familiarity with the topics required by the labor market, such as having a good command of various architectural software, familiarity with rules and regulations, and so on, 2. Having professional ethics, and 3. Having interactive skills. Conclusion: Based on the benefits of participatory education, it is proposed to turn architecture schools into "participatory education" environments in order to reduce the gap between education and professional work and decrease the low efficiency of architecture graduates in the professional environment. In this regard, it is possible to use the simultaneous training of students of different semesters in architecture courses and the presence of professional architects as expert individuals in some of the class sessions. In this way, students can benefit from each other's participation in design, critique of works, and improvement of skills related to the field of architecture, and the presence of professional architects in order to gradually acquire the skills required by the architectural job market. It is also possible to reduce the gap between education and professional work by establishing "NGOs" that are responsible for linking the university to architecture offices, job market and employers. ===================================================================================== COPYRIGHTS  ©2021 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

On the microstructure and mechanical properties of an Fe-10Ni-7Mn martensitic steel processed by high-pressure torsion.

High-pressure torsion (HPT) processing was applied to an Fe-10Ni-7Mn (wt.%) martensitic steel at room temperature and the grain size was reduced from an initial value of ~5.5 μm to an ultrafine value of ~185 nm for the ferritic phase and around 30 nm for the austenitic phase after 20 HPT turns. The microstructure and mechanical properties of the as-processed material were evaluated using X-ray diffraction (XRD), electron backscatter diffraction (EBSD), field emission scanning electron microscopy (FESEM), microhardness measurements and tensile testing. In addition, annealing of an as-processed specimen was analyzed by differential scanning calorimetry (DSC). The results show that HPT processing increases the hardness and ultimate tensile strength to ~690 Hv and ~2230 MPa, respectively, but the ductility is decreased from ~16.5% initially to ~6.4% and ~3.1% after 10 and 20 turns, respectively. The hardness distributions and EBSD images show that a reasonably homogeneous microstructure is formed when applying a sufficient level of pressure and torsional strain. The DSC results demonstrate that processing by HPT reduces the start and finish temperatures of the reverse transformation of martensite to austenite and there is continuous re-crystallization after the recovery process

Experimental Study of Natural Convective Flow over a Hot Horizontal Rhombus Cylinder Immersed in Water via PIV Technique

Natural convective flow over a horizontal cylinder is a phenomenon used in many industries such as heat transfer from an electrical wire, heat exchanger, pipe heat transfer, etc. In this research, fluid dynamics of natural convective flow over a horizontal rhombus cylinder, with uniform heat flux, is investigated by using two-dimensional Particle Image Velocimetry (PIV) Technique. Experiments are carried out in a cubical tank full of water having an interface with air and the cylinder is placed horizontally inside the tank. The heater is turned on for 40s and the effects of heater's power and the height of water above the cylinder are surveyed. The experiments are carried out in three different heights of water and two different heater’s powers in which Rayleigh number changes from 1.33×107 to 1.76×107. The emitted heat flux causes the buoyancy force to be made and the main branch of flow to be formed. Then, moving up the main branch flow through the stationary water generates two equal anti-direction vortexes. These vortexes are developed when they reach the free surface. The results indicate that the flow pattern changes for different values of water height and heater’s power

Alkali ratio control for lead-free piezoelectric thin films utilizing elemental diffusivities in RF plasma

High performance piezoelectric thin films are generally lead-based, and find applications in sensing, actuation and transduction in the realms of biology, nanometrology, acoustics and energy harvesting. Potassium sodium niobate (KNN) is considered to be the most promising lead-free alternative, but it is hindered by the inability to control and attain perfect stoichiometry materials in the thin film form while using practical large area deposition techniques. In this work, we identify the contribution of the elemental diffusivities in the radio frequency (RF) plasma in determining the alkali loss in the KNN thin films. We have also examined the effect of the substrate temperature during the RF magnetron sputtering deposition on the crystal structure of the substrate and KNN thin films, as well as the effect of the postannealing treatments. These results indicate the need for well-designed source materials and the potential to use the deposition partial pressure to alter the dopant concentrations