On the Necessity of Unsteady Flow in Fluid Machines

1959 ◽  
Vol 81 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Robert C. Dean
Keyword(s):  
Unsteady Flow ◽  
Fluid Machinery ◽  
Flow Process ◽  
Made In

It is shown that work can be done on, or by, a fluid in a frictionless flow process only if the flow is unsteady. The implications of this conclusion in the analysis of fluid machinery, and provisions which must be made in analysis to account for unsteady flow, are discussed.

scholarly journals Penerapan Teknologi RFID untuk Purwarupa Pencatatan Presensi Mahasiswa di Laboratorium Komputer

2017 ◽  
Vol 3 (2) ◽  
pp. 122
Author(s):  
Robby Tan ◽  
Djoni Setiawan Kartawihardja ◽  
Ivan Christian
Keyword(s):  
Information Technology ◽  
Student Identity ◽  
Rfid Technology ◽  
Flow Process ◽  
Presence Data ◽  
Identity Card ◽  
Process Work ◽  
Made In

Abstrak— Kehadiran mahasiswa merupakan salah satu bagian daripada proses akademik. Saat ini, Fakultas Teknologi Informasi masih menggunakan sistem pencatatan kehadiran mahasiswa dengan cara tanda tangan pada Daftar Hadir Mahasiswa dan Dosen (DHMD) yang kemudian setiap kehadiran mahasiswa akan dicatat kembali pada Sistem Akademik Terpadu (SAT). Proses penandatanganan DHMD ini kemungkinan dapat menyebabkan hilangnya konsentrasi mahasiswa karena diperlukan beberapa saat untuk tanda tangan sebelum kembali memperhatikan penjelasan dosen. Selain itu, sering terdapat kesalahan tanda tangan dalam arti mahasiswa menanda tangani baris presensi milik mahasiswa yang lain. Dalam menemukan solusi untuk masalah tersebut, dilakukan pembuatan purwarupa pencatatan presensi kehadiran yang tetap dapat dipantau oleh dosen sekaligus meminimalkan proses terjadinya kesalahan. Penelitian ini memanfaatkan teknologi RFID yang sudah dimiliki oleh dosen dan mahasiswa yaitu kartu dosen dan kartu tanda mahasiswa (KTM). Proses identifikasi kartu dan pembuatan proses jalannya pencatatan presensi secara digital dapat membantu proses akademik berjalan dengan baik. Simpulan dari penelitian yang telah dilakukan adalah data yang disimpan dalam RFID telah berhasil dibaca dan dibuat dalam bentuk data kehadiran secara digital.Kata Kunci— Presensi Mahasiswa, Purwarupa, RFIDAbstract—Student presence is one of many the academic process. Currently, Information Technology Faculty still uses student signature in Daftar Hadir Mahasiswa dan Dosen (DHMD) as proof of attendance. Every week, DHMD will be collected and student presence data will be inserted in Sistem Akademik Terpadu (SAT). The DHMD signing process is likely to lead to a loss of student concentration as it may take a while for the signature before returning to the lecturer's explanation. In addition, there are often signature errors in the sense that students sign other students' presences. In finding a solution to the problem, a prototype of presence attendance system is constructed so lecturer can monitor the while minimizing the process of the error occurring. This research utilizes RFID technology in form of the lecturer card and student identity card (KTM). The process of card identification and creating the flow process of capture digital presence can help the academic process work well. The conclusion of the research that has been done is the data stored in RFID has been successfully read and made in the form of digital attendance data.Keywords— Student Presence, Prototype, RFID

scholarly journals Unsteady Flow Process in Mixed Waterjet Propulsion Pumps with Nozzle Based on Computational Fluid Dynamics

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 910 ◽  
Author(s):  
Can Luo ◽  
Hao Liu ◽  
Li Cheng ◽  
Chuan Wang ◽  
Weixuan Jiao ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Guide Vane ◽  
Morphological Characteristics ◽  
Rotating Stall ◽  
Small Range ◽  
Computational Domain ◽  
Flow Process ◽  
Unstable Zone ◽  
Test Loop ◽  
Comprehensive Performance

The unsteady flow process of waterjet pumps is related to the comprehensive performance and phenomenon of rotating stall and cavitation. To analyze the unsteady flow process on the unsteady condition, a computational domain containing nozzle, impeller, outlet guide vane (OGV), and shaft is established. The surface vortex of the blade is unstable at the valley point of the hydraulic unstable zone. The vortex core and morphological characteristics of the vortex will change in a small range with time. The flow of the best efficiency point and the start point of the hydraulic unstable zone on each turbo surface is relatively stable. At the valley point of the hydraulic unstable zone, the flow and pressure fields are unstable, which causes the flow on each turbo surface to change with time. The hydraulic performance parameters are measured by establishing the double cycle test loop of a waterjet propulsion device compared with numerical simulated data. The verification results show that the numerical simulation method is credible. In this paper, the outcome is helpful to comprehend the unsteady flow mechanism in the pump of waterjet propulsion devices, and improve and benefit their design and comprehensive performance.

Numerical analysis of vertical water movement in a bounded profile

Soil Research ◽  
1975 ◽  
Vol 13 (1) ◽  
pp. 1 ◽  
Author(s):  
KK Watson ◽  
AA Curtis
Keyword(s):  
Water Movement ◽  
Sandy Loam ◽  
Air Pressure ◽  
Wetting Front ◽  
Flow Process ◽  
Compression Effect ◽  
Cumulative Infiltration ◽  
Computer Based ◽  
Air Compression ◽  
Made In

The usual assumption made in soil water studies that the effect of the air phase on the flow process is negligible is discussed in relation to certain profile configurations where such an assumption is not valid. A computer-based numerical solution of the equation describing water movement in an unsaturated soil is then modified by the inclusion of a time-dependent boundary condition, thus allowing the modelling of the air compression effect during infiltration. This analysis also satisfactorily models the drainage along primary draining scanning curves which occurs in the upper part of the profile as the air pressure increases. The analysis is limited to the Darcy flow regime which, for the system considered, terminates when the excess air pressure equals the air entry value of the porous material. Detailed results are presented for a sand and a sandy loam. Profile depths of 200 cm and 1000 cm have been analysed, and comparisons made of the effect of the air compression on the shape of the wetting front. The effect on cumulative infiltration is also noted.

scholarly journals Evaluation of a High-Accuracy MacCormack-Type Scheme Using Benchmark Problems

1998 ◽  
Vol 06 (03) ◽  
pp. 291-305 ◽  
Author(s):  
R. Hixon
Keyword(s):  
Wave Propagation ◽  
Unsteady Flow ◽  
High Accuracy ◽  
Benchmark Problems ◽  
Linear Wave ◽  
Propagation Characteristics ◽  
Reasonable Amount ◽  
Maccormack Scheme ◽  
Linear Wave Propagation ◽  
Made In

Due to their inherent dissipation and stability, the MacCormack scheme and its variants have been widely used in the computation of unsteady flow and acoustic problems. However, these schemes require many points per wavelength in order to propagate waves with a reasonable amount of accuracy. Recently, much progress has been made in improving the wave propagation qualities of MacCormack-type schemes. In this work, the linear wave propagation characteristics of MacCormack-type schemes are compared using several of the CAA Benchmark Problems.

scholarly journals TIME-LAG OF DUNES FOR UNSTEADY FLOW CONDITIONS

1978 ◽  
Vol 1 (16) ◽  
pp. 109
Author(s):  
Horst Nasner
Keyword(s):  
Unsteady Flow ◽  
Time Lag ◽  
Flow Conditions ◽  
The Past ◽  
Bed Forms ◽  
Hydraulic Conditions ◽  
Bed Form ◽  
Theoretical Considerations ◽  
Reconstruction Time ◽  
Made In

Many publications based on theoretical considerations or model tests, give utterance to the demand that there should be unequivocal relations between hydraulic conditions and bed form characteristics which should be generally applicable. These relationships determined for steady conditions and limited water depths should be handled with care when being applied to natural rivers. The bed configurations do not immediately fit themselves to the varying flow conditions. The bed forms need a certain reconstruction time in case of a changing discharge. The time-lag of dunes was observed on numerous rivers, in the past. A general review of investigations made in this field is given by ALLEN (1976 b). In the following contribution, an attempt is made to describe the magnitude of the time lag of bed forms for unsteady flow conditions.

scholarly journals INVESTIGATING THE STABILITY OF LONG ONE- DIMENSIONAL WAVES IN A SLOPING RUNOFF

World Science ◽  
2020 ◽  
Vol 1 (1(53)) ◽  
pp. 18-22
Author(s):  
Otar Natishvili ◽  
Irakli Kruashvili ◽  
Irma Inashvili
Keyword(s):  
Free Surface ◽  
Soil Erosion ◽  
Unsteady Flow ◽  
Shallow Water ◽  
Flow Process ◽  
Variable Flow ◽  
One Dimensional ◽  
Continuous Waves ◽  
The Stability ◽  
The Way

The paper is dedicated to the problem of the influence of waves in shallow-water slope flows on the intensity of soil erosion that has not been considered earlier. The stability of one-dimensional continuous waves on the free surface of the sloping runoff is analyzed, both at constant, and with the variable flow along the way. Attention is drawn towards the unsteady flow process and the shape of the free surface in various planes.

Spectrophotometric measurements of objective-prism spectra

1966 ◽  
Vol 24 ◽  
pp. 118-119
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Progress Report ◽  
Two Dimensional ◽  
Objective Prism ◽  
Made In

I should like to give you a very condensed progress report on some spectrophotometric measurements of objective-prism spectra made in collaboration with H. Leicher at Bonn. The procedure used is almost completely automatic. The measurements are made with the help of a semi-automatic fully digitized registering microphotometer constructed by Hög-Hamburg. The reductions are carried out with the aid of a number of interconnected programmes written for the computer IBM 7090, beginning with the output of the photometer in the form of punched cards and ending with the printing-out of the final two-dimensional classifications.

Surface Structure in Microtomed Sections Caused by Glass and Diamond Knives

1971 ◽  
Vol 29 ◽  
pp. 456-457
Author(s):  
J. Temple Black ◽  
William G. Boldosser
Keyword(s):  
Plastic Deformation ◽  
Epoxy Resin ◽  
Carbon Coating ◽  
Surface Damage ◽  
Body Angle ◽  
Normal Manner ◽  
Bottom Side ◽  
Cutting Direction ◽  
Made In ◽  
Diamond Knife

Ultramicrotomy produces plastic deformation in the surfaces of microtomed TEM specimens which can not generally be observed unless special preparations are made. In this study, a typical biological composite of tissue (infundibular thoracic attachment) infiltrated in the normal manner with an embedding epoxy resin (Epon 812 in a 60/40 mixture) was microtomed with glass and diamond knives, both with 45 degree body angle. Sectioning was done in Portor Blum Mt-2 and Mt-1 microtomes. Sections were collected on formvar coated grids so that both the top side and the bottom side of the sections could be examined. Sections were then placed in a vacuum evaporator and self-shadowed with carbon. Some were chromium shadowed at a 30 degree angle. The sections were then examined in a Phillips 300 TEM at 60kv.Carbon coating (C) or carbon coating with chrom shadowing (C-Ch) makes in effect, single stage replicas of the surfaces of the sections and thus allows the damage in the surfaces to be observable in the TEM. Figure 1 (see key to figures) shows the bottom side of a diamond knife section, carbon self-shadowed and chrom shadowed perpendicular to the cutting direction. Very fine knife marks and surface damage can be observed.

Iron storage sites in the myocardium as revealed by cytohistochemistry

1988 ◽  
Vol 46 ◽  
pp. 394-395
Author(s):  
M. Ashraf ◽  
F. Thompson ◽  
S. Miki ◽  
P. Srivastava
Keyword(s):  
Cardiac Tissue ◽  
Coronary Perfusion ◽  
Intracellular Iron ◽  
Ether Anesthesia ◽  
Intense Staining ◽  
Iron Storage ◽  
Thin Sections ◽  
Rat Hearts ◽  
Cacodylate Buffer ◽  
Made In

Iron is believed to play an important role in the pathogenesis of ischemic injury. However, the sources of intracellular iron in myocytes are not yet defined. In this study we have attempted to localize iron at various cellular sites of the cardiac tissue with the ferrocyanide technique.Rat hearts were excised under ether anesthesia. They were fixed with coronary perfusion with 3% buffered glutaraldehyde made in 0.1 M cacodylate buffer pH 7.3. Sections, 60 μm in thickness, were cut on a vibratome and were incubated in the medium containing 500 mg of potassium ferrocyanide in 49.5 ml H2O and 0.5 ml concentrated HC1 for 30 minutes at room temperature. Following rinses in the buffer, tissues were dehydrated in ethanol and embedded in Spurr medium.The examination of thin sections revealed intense staining or reaction product in peroxisomes (Fig. 1).

Microanalysis of precipitates in a ferritic steel

1978 ◽  
Vol 36 (1) ◽  
pp. 618-619
Author(s):  
J.M. Titchmarsh
Keyword(s):  
Ferritic Steel ◽  
Particle Identification ◽  
Energy Dispersive ◽  
Objective Lens ◽  
Ferritic Steels ◽  
Replica Technique ◽  
X Ray ◽  
Large Numbers ◽  
Scanning Transmission ◽  
Made In

The advances in recent years in the microanalytical capabilities of conventional TEM's fitted with probe forming lenses allow much more detailed investigations to be made of the microstructures of complex alloys, such as ferritic steels, than have been possible previously. In particular, the identification of individual precipitate particles with dimensions of a few tens of nanometers in alloys containing high densities of several chemically and crystallographically different precipitate types is feasible. The aim of the investigation described in this paper was to establish a method which allowed individual particle identification to be made in a few seconds so that large numbers of particles could be examined in a few hours.A Philips EM400 microscope, fitted with the scanning transmission (STEM) objective lens pole-pieces and an EDAX energy dispersive X-ray analyser, was used at 120 kV with a thermal W hairpin filament. The precipitates examined were extracted using a standard C replica technique from specimens of a 2¼Cr-lMo ferritic steel in a quenched and tempered condition.

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