Solar Collector Durability Evaluation by Stagnation Temperature Measurements

1983 ◽  
Vol 105 (3) ◽  
pp. 259-267 ◽  
Author(s):  
A. G. Dawson ◽  
W. C. Thomas ◽  
D. Waksman
Keyword(s):  
Prolonged Exposure ◽  
Test Method ◽  
Experimental Results ◽  
Analytical Models ◽  
Energy Output ◽  
Stagnation Temperature ◽  
Solar Absorptance ◽  
Before And After ◽  
Materials Used ◽  
Degradation Of Materials

An analytical and experimental investigation was undertaken to evaluate an alternative method for measuring the thermal degradation of materials used in flat-plate collectors. This test method is based on measuring the temperature of the absorber under a no-flow condition before and after prolonged exposure. The primary material properties of interest are cover transmittance, solar absorptance and infrared emittance of the absorber, and thermal conductivity of insulation. The advantages and limitations of the proposed test method are compared with those for the currently used method, which is based on measuring the energy output from collectors. Experimental results from both outdoor and indoor tests are presented. Steady-state and transient analytical models are developed to evaluate the proposed test method and interpret experimental results. While the measurements required in the proposed method are simpler than those used to measure energy output, other factors, such as nonisothermal absorbers, variations in environmental conditions, and transient response, must be reconciled.

Use of Integrated Day-Long Stagnation Temperature for Measuring Changes in Solar Collector Materials Properties

1985 ◽  
Vol 107 (2) ◽  
pp. 170-175
Author(s):  
W. C. Thomas ◽  
A. G. Dawson ◽  
D. Waksman
Keyword(s):  
Analytical Model ◽  
Test Procedure ◽  
Daily Basis ◽  
Test Methods ◽  
Test Method ◽  
Solar Irradiation ◽  
Stagnation Temperature ◽  
Nonsteady State ◽  
Materials Used ◽  
Energy Absorbing

Measurements of the maximum temperatures reached by solar-energy-absorbing surfaces provide a useful method for detecting possible degradation in the optical and heat transfer properties of materials used in collectors. This investigation shows that a method based on integrating the absorber temperature rise over ambient and solar irradiation on a daily basis has advantages over alternative test methods based on steady-state measurements of either absorber stagnation temperature or collector thermal efficiency. A nonsteady-state analytical model is developed and used to evaluate the sensitivity of the proposed test method to material degradation and environmental effects. Outdoor data are presented to validate the analytical model and depict typical results that can be expected using the test procedure.

Deformation Replication

1970 ◽  
Vol 28 ◽  
pp. 280-281
Author(s):  
J. Temple Black
Keyword(s):  
Cutting Speed ◽  
Machining Process ◽  
Depth Of Cut ◽  
Rake Face ◽  
Orthogonal Machining ◽  
Aluminum Chips ◽  
Before And After ◽  
Materials Used ◽  
Glass Knife ◽  
Very High

Tool materials used in ultramicrotomy are glass, developed by Latta and Hartmann (1) and diamond, introduced by Fernandez-Moran (2). While diamonds produce more good sections per knife edge than glass, they are expensive; require careful mounting and handling; and are time consuming to clean before and after usage, purchase from vendors (3-6 months waiting time), and regrind. Glass offers an easily accessible, inexpensive material ($0.04 per knife) with very high compressive strength (3) that can be employed in microtomy of metals (4) as well as biological materials. When the orthogonal machining process is being studied, glass offers additional advantages. Sections of metal or plastic can be dried down on the rake face, coated with Au-Pd, and examined directly in the SEM with no additional handling (5). Figure 1 shows aluminum chips microtomed with a 75° glass knife at a cutting speed of 1 mm/sec with a depth of cut of 1000 Å lying on the rake face of the knife.

Investigations of Road Wear Caused by Studded Tires

2014 ◽  
Vol 42 (1) ◽  
pp. 2-15
Author(s):  
Johannes Gültlinger ◽  
Frank Gauterin ◽  
Christian Brandau ◽  
Jan Schlittenhard ◽  
Burkhard Wies
Keyword(s):  
Traffic Safety ◽  
Test Bench ◽  
Operating Conditions ◽  
Test Method ◽  
Analytical Models ◽  
The Road ◽  
Driving Speed ◽  
Major Factors ◽  
Tire Friction ◽  
Variable Operating Conditions

ABSTRACT The use of studded tires has been a subject of controversy from the time they came into market. While studded tires contribute to traffic safety under severe winter conditions by increasing tire friction on icy roads, they also cause damage to the road surface when running on bare roads. Consequently, one of the main challenges in studded tire development is to reduce road wear while still ensuring a good grip on ice. Therefore, a research project was initiated to gain understanding about the mechanisms and influencing parameters involved in road wear by studded tires. A test method using the institute's internal drum test bench was developed. Furthermore, mechanisms causing road wear by studded tires were derived from basic analytical models. These mechanisms were used to identify the main parameters influencing road wear by studded tires. Using experimental results obtained with the test method developed, the expected influences were verified. Vehicle driving speed and stud mass were found to be major factors influencing road wear. This can be explained by the stud impact as a dominant mechanism. By means of the test method presented, quantified and comparable data for road wear caused by studded tires under controllable conditions can be obtained. The mechanisms allow predicting the influence of tire construction and variable operating conditions on road wear.

MODEL MANAJEMEN PENDIDIKAN KARAKTER BERBASIS INTEGRASI NILAI-NILAI RELIGIUS DAN MULTIKULTURAL

2019 ◽  
Vol 20 (2) ◽  
pp. 227-266
Author(s):  
Rohmat Rohmat
Keyword(s):  
Character Education ◽  
Future Generation ◽  
T Test ◽  
Test Method ◽  
Intellectual Ability ◽  
Management Model ◽  
Education Management ◽  
Model Based ◽  
Before And After ◽  
Emotional Aspects

Securing religious and multicultural character values ​​is very important to be instilled as early as possible through education. This is due to education not only providing increased intellectual ability, but also is responsible for integrating character values ​​in students. At least there are some aspects that need to be developed in the education phase of school children including intellectual aspects, emotional aspects, social aspects, physical aspects, aspects of movement, aesthetic aspects, and moral aspects. Based on this opinion it can be seen that the cultivation of religious and multicultural character values ​​in madrasa ibtidaiyah level students needs to be done in order to realize a future generation of adults and character. On the other hand, the cultivation of multicultural values ​​is also an urgent matter to do.This study aims to find a character education management model based on the integration of religious and multicultural values ​​in MI Banyumas Regency. The research method with research and development methods. The results of the study of the character education management model based on the integration of religious and multicultural values ​​that were developed effectively for use in character education in Madrasah Ibtidaiyah. The results of the t test through the paired t test method showed that there were significant differences between the character values ​​before and after the implementation of character education in Madrasah Ibtidaiyah. These results reinforce that character education is effectively used in Madrasah Ibtidaiyah.

EVALUATION OF TRIBOTECHNICAL PROPERTIES OF THE COATING OBTAINED BY ELECTRIC SPARK HARDENING

2020 ◽  
Vol 4 (141) ◽  
pp. 157-163
Author(s):  
IL’YA ROMANOV ◽  
◽  
ROMAN ZADOROZHNIY
Keyword(s):  
Wear Resistance ◽  
Reference Sample ◽  
Optical Microscope ◽  
Research Purpose ◽  
Tribotechnical Properties ◽  
Uncoated Surface ◽  
Before And After ◽  
Materials Used ◽  
Friction Track

When applying coatings using various methods on the surfaces of moving parts that work in joints, it is important to make sure that the coatings are strong and wear-resistant in order to return them to their original resource. All existing hardening technologies and materials used to perform coatings have their own characteristics, therefore, the quality of the resulting coatings can be judged only after specific tests. (Research purpose) The research purpose is in evaluating the properties of the coating obtained by the method of electric spark hardening, and its ability to resist friction and mechanical wear. (Materials and methods) Authors conducted tests on the basis of the "Nano-Center" center for collective use. A coating was applied on the BIG-4M unit with a VK-8 hard alloy electrode, tribological properties were evaluated on a CSM Instruments TRB-S-DE-0000 tribometer, the width of the friction track was measured after the test using an inverted OLYMPUS gx51 optical microscope, and samples were weighed before and after the test on a VLR-200 analytical balance. Conducted research in accordance with GOST 23.224-86 and RD 50-662-88 guidelines. (Results and discussion) The article presents performed tests on the run-in and wear resistance of the coating. The samples were worked on with a step-by-step increase in the load. During the tests, the friction force was drawed on the diagram. Authors compared the results with the reference sample, an uncoated surface. (Conclusions) The resulting coating has better run-in and wear resistance compared to the standard, and the increase in wear resistance in dry friction conditions is very significant.

scholarly journals Experimental Study on the Water Selective Dense Membrane under an Absolute Pressure Difference with Simplified Test Method

2021 ◽  
Vol 11 (4) ◽  
pp. 1710
Author(s):  
Jinwook Lee ◽  
Hyo-Sun Kim ◽  
Donik Ku ◽  
Jihun Lim ◽  
Minkyu Jung ◽  
...  
Keyword(s):  
Measurement Methods ◽  
Test Method ◽  
Coefficient Of Performance ◽  
Absolute Pressure ◽  
Air Conditioner ◽  
Experimental Conditions ◽  
Simple Method ◽  
Performance Factors ◽  
Dense Membrane ◽  
Before And After

Membrane-based vacuum dehumidification technology is currently being actively studied. In most studies, the performance of the membrane-based systems is evaluated under the assumption that the membrane can achieve ideal separation, which results in ideal coefficient of performance (COP) values. However, the performance factors for membranes vary depending on the experimental conditions and measurement methods. Therefore, relevant values can only be calculated if the data are measured in an environment close to that of the application conditions. The cup measurement method is a simple method to measure the permeability, however, there are limitations regarding adding variables during the experiment. To overcome these limitations, a new experimental device was constructed that combines pressurized cell with the cup method. Using the device, the performance of polyethylene-amide-bonded dense membranes was evaluated under conditions where absolute pressure differentials occurred before and after the membrane, such as in air conditioner dehumidification systems.

Monitoring fisheries resources at offshore wind farms: BACI vs. BAG designs

2020 ◽  
Vol 77 (3) ◽  
pp. 890-900
Author(s):  
Elizabeth T Methratta
Keyword(s):  
Statistical Power ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Cultural Value ◽  
Analytical Models ◽  
Offshore Wind Farms ◽  
Fisheries Resources ◽  
Unaffected Control ◽  
Before And After

Abstract Offshore wind farms often co-occur with biodiverse marine ecosystems with high ecological, economic, and cultural value. Yet there are many uncertainties about how wind farms affect marine organisms and their environment. The before–after–control–impact (BACI) design, an approach that compares an impact location with an unaffected control both before and after the intervention, is the most common method used to study how offshore wind farms affect finfish. Unfortunately, this design has several methodological limitations that undermine its ability to detect effects in these studies. An alternative approach, the before–after-gradient (BAG) design, would sample along a gradient with increasing distance from the turbines both before and after the intervention, and could overcome many of the limitations of BACI. The BAG design would eliminate the difficult task of finding a suitable control, allow for the assessment of the spatial scale and extent of wind farm effects, and improve statistical power by incorporating distance as an independent variable in analytical models rather than relegating it to the error term. This article explores the strengths and weaknesses of the BACI and BAG designs in the context of offshore wind development and suggests an approach to incorporating the BAG design into existing fisheries surveys and a regional monitoring framework.

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