scholarly journals Rotational Compression of Cylindrical Specimen As a New Calibrating Test for Damage Criteria

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 740 ◽  
Author(s):  
Zbigniew Pater ◽  
Janusz Tomczak ◽  
Tomasz Bulzak ◽  
Łukasz Wójcik ◽  
Patrycja Walczuk-Gągała
Keyword(s):  
Accurate Determination ◽  
Cylindrical Sample ◽  
Damage Function ◽  
Actual Process ◽  
Limit Values ◽  
University Of Technology ◽  
Fracture Damage ◽  
Material Fracture ◽  
Fracture Of Materials ◽  
Damage Criteria

The subject-matter of the article is the ductile fracture of materials—A phenomenon occurring in numerous metal forming processes. In order to prognosticate the possibility of a fracture, damage criteria are employed. Their effectiveness, however, depends on the accurate determination of the critical values of damage. These values are obtained through calibrating tests, where the stress state has to be as similar to the actual process as possible. The currently employed calibrating tests do not enable one to determine the limit values of the damage function when the Mannesmann effect occurs. Therefore it was not possible to effectively prognosticate the material fracture in the processes of cross- and skew-rolling. A new calibrating test, based on rotational compression of a cylindrical sample, in which the fractures are caused by the Mannesmann effect, was developed at the Lublin University of Technology. This test was discussed in the article, with a particular focus on the stress and strain state in the sample. A practical use of the test was presented on the example of C45 grade steel, formed in the temperature equal 1150 °C. In the research ten material damage criteria were adopted.

scholarly journals Prediction of Crack Formation for Cross Wedge Rolling of Harrow Tooth Preform

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2287 ◽  
Author(s):  
Zbigniew Pater ◽  
Janusz Tomczak ◽  
Tomasz Bulzak ◽  
Jarosław Bartnicki ◽  
Arkadiusz Tofil
Keyword(s):  
Crack Formation ◽  
Experimental Testing ◽  
Critical Value ◽  
Cross Wedge Rolling ◽  
Laboratory Conditions ◽  
University Of Technology ◽  
Material Fracture ◽  
Damage Criteria

The article presents the issue of material fracture during the process of cross-wedge rolling (CWR). The object of the research was the process of forming a harrow tooth preform. In the conducted analysis nine damage criteria were applied. The critical value of damage was determined with a new calibrating test, basing on rotational compression of a sample in a channel. The results of calculations were compared to the results of experimental testing performed in laboratory conditions in Lublin University of Technology. On the basis of the obtained results an assessment of the applied damage criteria and their applicability in the analysis of CWR processes was conducted.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

A Rapid Radioisotope Dilution Technique for the Accurate Determination of the Cardiac Output

1968 ◽  
Vol 07 (01) ◽  
pp. 1-7
Author(s):  
Muhammad Razzak ◽  
Robert Botti ◽  
William MacIntyre
Keyword(s):  
Cardiac Output ◽  
Isotope Dilution ◽  
Accurate Determination ◽  
Differential Count ◽  
Stroke Index ◽  
Recording Device ◽  
Dilution Curve ◽  
Index Stroke Volume ◽  
Index Stroke ◽  
Comparison Of The Results

SummaryA pair of printing scalers was used to record the information obtained by external monitoring of the isotope dilution curve following the intravenous injection of radioiodinated human serum albumin. The first scaler gives the differential count rate of the curve at increments of one second, whereas the second integrates continuously the isotope dilution curve. This recording device enabled cardiac output determinations to be calculated rapidly at the bedside without any loss in accuracy.Using this method in 15 normal individuals, the cardiac output was found to be 6.13 ± 0.73 liters/minute (Mean ± 1 S.D.), with a cardiac index of 3.36 ± 0.35 liters/minute/m2. In the same group of normals, the stroke index (stroke volume/surface area) amounted to 50 ± 7.3 ml/beat/m2.Comparison of the results of this method with those obtained by integration of the entire isotope dilution curve by an IBM 1620 computer showed excellent agreement, proving the validity of the suggested technique.

Study of the process of forming a hole for a thread at manufacturing a high nut

2020 ◽  
Vol 76 (8) ◽  
pp. 841-846
Author(s):  
I. G. Shubin ◽  
A. A. Kurkin
Keyword(s):  
Metal Flow ◽  
Nonlinear Dependence ◽  
Geometrical Parameters ◽  
Relative Height ◽  
Forming Process ◽  
Normal Height ◽  
Accuracy Class ◽  
Limit Values ◽  
Program Complex ◽  
Class B

During manufacturing nuts of increased height, a problem of obtaining correct cylindrical form of the hole for thread and overall geometrical parameters arises. To solve the problem it is necessary to know regularity of the blank forming process. Results of the study of a technological process of high hexahedral nuts forming presented. The nuts were M18 of 22 mm height, M16 of 19 mm height and M12 of normal height 10 mm according to GOST 5915–70, accuracy class B, steel grade 10 according to GOST 10702–78. The volumetric stamping was accomplished at the five-position automatic presses of АА1822 type. It was determined, that unevenness of the metal flow in the process of plastic deformation of blanks of increased height nuts was caused by different stress conditions by their sections. To simulate the mode of deformation, the program complex QForm-3D was chosen. The complex ensured to forecast with necessary accuracy the metal flow in a blank, as well as to define the deformation force and arising stress in the working instrument. The simulation showed the presence of regularity between preliminary formed buffle and deviation of dimensions and form of a blank wall after its finishing piercing, which can be expressed by a nonlinear dependence. The limit values of the relative height of the buffle С/D = 0.56–0.588 defined, exceeding which will result in rejection of the finished product. Accounting the limit values of the relative height of the buffle will enable to correct a mode of technological operations and technological instruments at stamping of high hexahedral nuts.

A RETROSPECTIVE STUDY ON ANTIBIOTIC USAGE IN A TERTIARY CARE HOSPITAL

2020 ◽  
Vol 4 (6) ◽  
Author(s):  
Anna Joy ◽  
Aparna Anand ◽  
Arathy R Nath ◽  
Meera S Nair ◽  
Dr. K. G. Prasanth
Keyword(s):  
Retrospective Study ◽  
Tertiary Care ◽  
Antibiotic Sensitivity ◽  
Sensitivity Test ◽  
Actual Process ◽  
Care Hospital ◽  
Rational Use ◽  
Antibiotic Susceptibility Test ◽  
Antibiotic Sensitivity Test ◽  
Rational Use Of Antibiotics

Antibiotics are one of the most commonly prescribed drugs today. Rational use of antibiotics is therefore extremely important as their injudicious use can adversely affect the patient. Drug Utilization Evaluation (DUE) is a system of ongoing systematic criteria based evaluation of drug that will help to ensure that medicines are used appropriately. It is drug/disease specific and can be structured so that it will assess the actual process of prescribing, dispensing, or administration of drug. The retrospective study was conducted At Pk Das Institute of Medical Sciences, Palakkad, Kerala for a duration of 6 months (February 2017 - January 2018). A source of data includes Patient case sheets &medication charts, nursing charts, culture & sensitivity reports. The inclusion criterion includes Patients aged between 18- 80 year, prescribed with oral and parenteral antibiotics. . On analyzing the gender, male gender (n= 111, 55.5%) were higher in numbers as compared to female counterparts (n=89, 44.5%). In our study the majority of the patients prescribed with antibiotics were with the clinical assessment of COPD (n=39, 19.5%), UTI (n=37, 18.5%) and LRTI (n=28, 14%), Bronchial asthma (n=19, 9.5%) respectively. On analyzing the data based on antibiotic sensitivity test, antibiotic test were performed and followed in (n=64,32%)prescriptions and in (n=47,23.5%)prescriptions were test is not followed respectively. In (n=89,44.5%) prescriptions, antibiotic sensitivity test is not performed. On analysis of antibiotics prescribed, the most commonly prescribed antibiotics were cephalosporins, of these ceftriaxone was highly prescribed of all (n=95). The high percentage of antibiotic prescriptions may indicate a high probability of irrational use. This study also point out irrational use of antibiotics are more leading to resistance, misuse and serious problems. So certain strategies should be put forward to strengthen rational use of antibiotics. Keywords: Antibiotics, Antibiotic Susceptibility Test, Irrational use, Resistance

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