Parametric Studies on a Numerical, Nonlinear Pulse Tube Flow

1997 ◽  
Vol 119 (4) ◽  
pp. 831-837 ◽  
Author(s):  
C. S. Kirkconnell ◽  
G. T. Colwell
Keyword(s):  
Numerical Model ◽  
High Reliability ◽  
Low Cost ◽  
Method Of Lines ◽  
Pulse Tube ◽  
Governing Equations ◽  
Modeling Tools ◽  
The Method Of Lines ◽  
Commercial Applications ◽  
The One

The need for high reliability, low cost, low vibration cryocoolers, for both military and commercial applications, has spawned and continues to drive the development of pulse tube cryogenic refrigerators. The expander contains no moving parts, yielding the potential for marked improvements in these areas. Though pulse tube refrigeration has been thoroughly studied, more accurate analytic and numerical modeling tools are needed to facilitate the development of thermodynamically efficient pulse tube cryocoolers to meet the needs of the user community. At present, one of the primary areas of modeling uncertainty is in the calculation of the dissipative losses occurring within the pulse tube itself. Toward this end, a numerical model was developed to solve the one-dimensional, nonlinear governing equations for heat and mass flow in a pulse tube. The governing equations are scaled for high-frequency (>60 Hz) pulse lube operation. The resulting system of nonlinear, time-dependent equations was solved directly using the method of lines. The numerical model was verified analytically using a representative set of equations with a known solution. A sensitivity analysis was performed to investigate the influence of different parameters on the solution.

scholarly journals Development and Evaluation of a Portable Spectrophotometer

2019 ◽  
Vol 17 ◽  
pp. 113
Author(s):  
J. P. Cândico ◽  
A. P.P. Macedo ◽  
Eduardo Galembeck
Keyword(s):  
Undergraduate Students ◽  
Field Experiments ◽  
High Reliability ◽  
Low Cost ◽  
Field Studies ◽  
Push Button ◽  
Cuvette Holder ◽  
The One ◽  
Compact Design ◽  
Sd Card

INTRODUCTION: Colorimetric methods, such as proteins and glucose quantification, and enzymatic assays are widely performed in biochemical laboratories employing spectrophotometer equipment. Even being present in most of the labs that serve undergraduate students, low cost and portable spectrophotometers can be a valuable tool in high schools and for field studies. OBJECTIVES: We have assembled and evaluated a portable spectrophotometer, inspired in some open projects freely available on the Internet. MATERIALS AND METHODS: The system was built using an RGB LED as a light source and a light detector (TSL2561). These components were placed into the ends of a cuvette holder, which was designed in FREECAD software and fabricated in a 3D printer. The data collection system was developed using an Arduino UNO microcontroller, an LCD to show the absorbance, a micro SD card to store the results, and a push button to select the LED emitted light wavelength. All components were powered by battery bank of 2000mAh. The software was written in C++, and we used Arduino IDE 1.8.6. For the equipment evaluation, we ran protein (Bradford) and glucose (Somogyi-Nelson) essays comparing the results obtained from the developed equipment with the one used in our didactic lab (Biospectro SP-22). DISCUSSION AND RESULTS: The results obtained comparing both pieces of equipment shows a correlation coefficient of 0.99 for the both methods (Bradford and Somogyi-Nelson) in test-retest. The commercial equipment demonstrated the coefficient of variation higher than 10%, while developed spectrophotometer showed values lower than 5%. The power bank was able to supply energy to the equipment up to 12 hours. CONCLUSION: These results demonstrated high reliability for the data collected from the developed spectrophotometer. Besides the low cost, compact design and high battery autonomy. The developed equipment has presented as a valuable alternative for field experiments and in-class practices of biochemistry.

scholarly journals “Pushing the Envelope” a modeling-based approach to the development of organic, responsive architectural form

2007 ◽  
Vol 4 (1) ◽  
Author(s):  
David Yearley
Keyword(s):  
Low Cost ◽  
Full Scale ◽  
Perceived Fit ◽  
Modeling Tools ◽  
Architectural Form ◽  
Scale Modeling ◽  
Digital Modeling ◽  
Spatial Dimensions ◽  
Surrounding Space ◽  
Commercial Applications

This paper tests design procedures for the development of complex, organic architectural forms. It illustrates a postgraduate student design process, implementing a development sequence based on the intelligent manipulation of architectural envelopes using a variety of existing modeling tools and emerging digital techniques. These stages of development respond to imposed spatial and environmental constraints. The tests began with full-scale modeling of small segments. The major constraints at this stage were spatial requirements and the physical characteristics of materials. The forms derived from the bending properties of prestressed green timber and the dimensions of shingle cladding. This was followed by digital 3D modeling using common commercial applications. At this stage initial models were derived from a traditional space requirement brief. The envelopes for these activities were then manipulated to respond to the spatial limitations imposed by surrounding buildings. This digital modeling process metaphorically “pushed the limits” as vertices of the envelope model were stretched and shifted to achieve a perceived “fit” between the two sets of spatial dimensions. The spatially manipulated geometry was then imported into Ecotect, an environmental analysis package. As an example, the envelope’s morphology and cladding material options on the acoustic qualities of the surrounding space were tested. The improved geometry was then imported into a Virtual Reality room, in which the spatial experience was simulated in presentations to the design team and potential occupants. This room utilized six projectors to create an immersive experience to users wearing stereoscopic goggles, and moving in a space surrounded by three large screens, creating a CAVE-like presentation space. Finally there was an attempt to complete the circle by returning from the simulated world to the physical worlds, by creating full-scale models from the digital geometry. This included low-cost techniques such as the generation of paper facets, and the use of more expensive rapid prototyping technology.

The Nonlinear Dynamic Response of Functionally Graded Material Flat Spherical Shells Subjected to Thermal Loading

2012 ◽  
Vol 549 ◽  
pp. 580-583
Author(s):  
Yao Dai ◽  
Xiao Chong ◽  
Lei Zhang ◽  
Hong Qian Chen
Keyword(s):  
Functionally Graded Material ◽  
Thermal Loading ◽  
Method Of Lines ◽  
Functionally Graded ◽  
The Finite Element Method ◽  
Governing Equations ◽  
Spherical Shells ◽  
Nonlinear Dynamic Response ◽  
The Method Of Lines ◽  
Graded Material

The response of functionally graded material flat spherical shells subjected to thermal loading is studied using the method of lines. Based on the Kirchhoff straight normal hypothesis and Von Karman's geometrically nonlinear theory, the governing equations are obtained. A semi-analytical numerical method, viz. the method of lines is introduced. Then, the partial differential equations are transformed into ordinary differential ones. The numerical results of flat spherical shells are given and compared with ones of the finite element method. The effects of the material gradient parameters on the responses are discussed in details.

The Nonlinear Dynamic Response of Functionally Graded Material Flat Spherical Shells

2012 ◽  
Vol 479-481 ◽  
pp. 1399-1402 ◽  
Author(s):  
Yao Dai ◽  
Xiao Hong ◽  
Jun Feng Liu ◽  
Lei Zhang
Keyword(s):  
Functionally Graded Material ◽  
Method Of Lines ◽  
Functionally Graded ◽  
Geometrically Nonlinear ◽  
The Finite Element Method ◽  
Governing Equations ◽  
Spherical Shells ◽  
Nonlinear Dynamic Response ◽  
The Method Of Lines ◽  
Graded Material

The response of functionally graded material (FGM) flat spherical shell under mechanical loading is studied using the method of lines. Based on the Kirchhoff straight normal hypothesis and Von Karman's geometrically nonlinear theory, the governing equations of the response of FGM flat spherical shells are obtained. A semi-analytical numerical method, i.e. the method of lines was introduced, and then the partial differential equations were transformed into ordinary differential ones. The effects of the material gradient parameters on the responses are discussed in details. The numerical results of flat spherical shells are given and compared with the finite element method ones.

Design of Auto Dust Collection System in Different Regions of Blackboard

2014 ◽  
Vol 1044-1045 ◽  
pp. 767-769
Author(s):  
Wei Wei ◽  
Dong Guo ◽  
Li Ding Liu
Keyword(s):  
Control System ◽  
High Efficiency ◽  
High Reliability ◽  
Low Cost ◽  
Basic Structure ◽  
Collection System ◽  
Dust Collection ◽  
Design Work ◽  
The One ◽  
Logical Functions

New blackboard dust collection system mainly be used for conventional teawching actions. It divided board into four different regions without changing basic structure, when people go into the view of sensor in the one of regions which will drive the quit fans to collect the dust produced during writing and clearing words on the board. The device includes two parts, mechanical structure and the region control system. For structure, be made up with up and down parts, the dusting devices and fans are chose by the stress analysis of the dust model, and then begin design work. For control system, using photo-electric switch to drive fans, and the angle of wind board is controlled by DC motor, and chip microcomputer STC89C52 is chose as the system core to achieve logical functions. The system can effectively reduce the harm from dust to the human and equipments during teaching. It has great characteristics including high efficiency and energy saving, low cost, simple structure, easy operation, high reliability and practicality.

scholarly journals Combining Interior Orientation Variables to Predict the Accuracy of Rpas–Sfm 3D Models

2020 ◽  
Vol 12 (17) ◽  
pp. 2674 ◽  
Author(s):  
Alessandra Capolupo ◽  
Mirko Saponaro ◽  
Enrico Borgogno Mondino ◽  
Eufemia Tarantino
Keyword(s):  
Mean Squared Error ◽  
High Reliability ◽  
Low Cost ◽  
3D Models ◽  
Time Data ◽  
Prediction Function ◽  
The One ◽  
Processing Techniques ◽  
Predictive Functions ◽  
Aerial Systems

Remotely piloted aerial systems (RPAS) have been recognized as an effective low-cost tool to acquire photogrammetric data of low accessible areas reducing collection and processing time. Data processing techniques like structure from motion (SfM) and multiview stereo (MVS) techniques, can nowadays provide detailed 3D models with an accuracy comparable to the one generated by other conventional approaches. Accuracy of RPAS-based measures is strongly dependent on the type of adopted sensors. Nevertheless, up to now, no investigation was done about relationships between camera calibration parameters and final accuracy of measures. In this work, authors tried to fill this gap by exploring those dependencies with the aim of proposing a prediction function able to quantify the potential final error in respect of camera parameters. Predictive functions were estimated by combining multivariate and linear statistical techniques. Four photogrammetric RPAS acquisitions were considered, supported by ground surveys, to calibrate the predictive model while a further acquisition was used to test and validate it. Results are preliminary, but promising. The calibrated predictive functions relating camera internal orientation (I.O.) parameters with final accuracy of measures (root mean squared error) showed high reliability and accuracy.

Sign in / Sign up

Export Citation Format

Share Document