screen mesh
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Author(s):  
Mahboobe Mahdavi ◽  
Amir Faghri

Abstract A comprehensive three-dimensional numerical model is developed to evaluate the effect of bending on water-copper cylindrical heat pipes. This model distinguishes itself from other models by its ability to uniquely determine the operating pressure of the heat pipe based on the operating and physical conditions. The effects of one 90-degree bend and two 90-degree bends are evaluated on the performance of a heat pipe. Two types of wicks are considered: a screen mesh wick and a sintered powder wick. The obtained results show that bending does affect the vapor pressure drop; however, the changes are not significant when compared to the operating pressure of the heat pipe. If the bending is performed in a manner where the wick is not damaged and the liquid is not blocked from returning to the evaporator, the performance of the heat pipe will not be affected significantly. In addition, if the heat pipe is operating in the horizontal direction, where both evaporator and condenser legs are at the same level, bending does not affect the liquid pressure drop significantly; however, the screen mesh does provide a higher capillary limit. The results also showed that the effects of gravity can be important when bending heat pipes and consideration should be given for this factor. When the bent heat pipe works against gravity, the sintered powder wick heat pipes showed higher capillary limits.


2021 ◽  
Vol 1139 (1) ◽  
pp. 012006
Author(s):  
B Herrera ◽  
F Chejne ◽  
M B H Mantelli ◽  
J Mejía ◽  
K Cacua
Keyword(s):  

Author(s):  
B. Ch Nookaraju ◽  
P. Keziya Rani ◽  
P.S.V. Kurmarao ◽  
S. Naga Sarada ◽  
N. Sateesh ◽  
...  

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242719
Author(s):  
Qingjie Qi ◽  
Xinlei Jia ◽  
Xinhua Zhou ◽  
Youxin Zhao

The internal collapse of deep seam drainage borehole and negative pressure loss represents a serious technical problem affecting gas drainage. To address this problem a creep model of coal around borehole was established based on the plastic softening characteristics of coal. The final collapse time of the borehole was determined and used to derive the three stages of the borehole collapse process. The model of negative pressure loss in drainage borehole was established according to the theory of fluid dynamics, the model of methane gas flow and the creep model of the coal around the borehole. The relationship between the negative pressure loss of drainage and the change of borehole aperture was derived, thereby revealing the main influencing factors of the negative pressure loss in the borehole. A drainage technique named “Full-hole deep screen mesh pipe” was introduced and tested to prevent the collapse of borehole and reduce the negative pressure loss. The result shows that after the borehole was drilled, the borehole wall was affected by the complex stress of the deep coal seam, the coal surrounding the borehole collapsed or presented the characteristics of creep extrusion towards the borehole. The “Full-hole deep screen mesh pipe drainage technology” could effectively control the collapse as well as the deformation of the borehole and reduced the negative pressure loss. Compared with the traditional drainage technology, the methane gas drainage concentration was increased by 101% and the gas flow was increased by 97% when the methane gas was drained for 90 days, the gas drainage efficiency increased significantly.


Author(s):  
Rasheda Begum Dina ◽  
Md Zulhash Uddin ◽  
UmmulKhair Fatema

In semi solid design, the parameters of the quality of the printed fabric were color fastness, level of print detail, color difference, print coverage, saw-tooth effect, line sharpness etc. Actually, printed fabric quality was evaluated by these parameters. Again, print coverage, saw-tooth effect, line sharpness, etc. were examined by estimating different distances, angles etc. in printed fabric and these factors were compared with image positives. Mesh opening effect on the quality of screen printed fabric was investigated after printing the semi solid design on knit fabric using different mesh count screens and different types of the link. To print semi solid design on knit fabric different types of ink as well as non-identical mesh count was used. Then mesh screen out come on the design and form of printed fabric in screen printing was examined. For the evaluation of semi solid design effect there remains two different methods.The first one is visual assessment and another way is microscope observation. Here, to determine the probability of the amount of ink flowing by the screen, mesh opening area of every screen was considered and it was done from respective digital microscope images.


2020 ◽  
Vol 20 (6) ◽  
Author(s):  
Christopher J Geden ◽  
Dana M Johnson ◽  
David B Taylor

Abstract Parasitoids are important natural enemies of house flies and other muscoid flies. The two most commonly used methods for collecting fly parasitoids from the field have distinct advantages and disadvantages. Collections of wild puparia depend on the ability to find puparia in sufficient numbers and are prone to localized distortions in relative species abundance because of the overrepresentation of samples from hot spots of fly larval activity. Placement and retrieval of sentinel puparia is convenient and allows consistent sampling over time but is strongly biased in favor of Muscidifurax spp. over Spalangia spp. An improved sentinel method is described that combines some of the advantages of these two methods. Fly medium containing larvae is placed in containers, topped with a screen mesh bag of puparia, and placed in vertebrate-proof wire cages. Cages are placed at sites of actual or potential fly breeding and retrieved 3–7 d later. The modified method collected species profiles that more closely resembled those of collections of wild puparia than those from sentinel pupal bags. A method is also described for isolating puparia individually in 96-well tissue culture plates for parasitoid emergence. Use of the plate method provided a substantial saving of time and labor over the use of individual gelatin capsules for pupal isolation. Puparia from the collections that were housed individually in the wells of tissue culture plates had a higher proportion of emerged Spalangia species than puparia that were held in groups.


2020 ◽  
Vol 2 (2) ◽  
pp. 133-138
Author(s):  
Iwan Setyawan ◽  
Sandy Reynaldy Riawan ◽  
Sri Poernomo Sari ◽  
Ridwan
Keyword(s):  

Pipa kalor merupakan salah satu jenis pendingin yang memanfaatkan sistem dua fase yang memiliki kemampuan memindahkan kalor yang cukup tinggi. Perangkat ini tidak mengkonsumsi energi mekanik dan kinerja termal tergantung pada struktur sumbu. Tujuan penelitian ini adalah untuk membuat pipa kalor lurus tembaga dengan sumbu kapiler Screen Mesh 300 sebanyak 6 layer.  Pada penelitian ini dilakukan pengujian dengan memvariasikan filling rasio, FR40%,60% dan 80%. Pengambilan data diambil menggunakan data aquisition Labjack U6 Pro. Termokopel ditempatkan di beberapa titik kemudian diolah dengan sistem labview. Dari hasil penelitian, didapatkan temperatur steady evaporator tertinggi dengan Filling Rasio 40% pada beban kalor 10W sampai 175W.  Untuk FR 80% menghasilkan temperatur evaporator yang paling rendah pada beban kalor 10W hingga 100W.  Untuk beban kalor yang lebih tinggi 175W hingga 275W, FR 60% menghasikan temperature evaporator terendah diantara FR 40% dan FR 80%. Selanjutnya, tahanan termal pada FR 80% menghasilkan nilai terbesar untuk semua beban kalor. Sedangkan FR 60% menghasilkan tahanan termal yang hampir sama dengan dengan FR 80% untuk beban kalor 25W hingga 275W. Namun demikian pada beban kalor 10W, FR 60% menghasilkan tahanan termal yang lebih rendah diantara FR40% dan FR 80%. Dengan demikian, dari hasil temperatur dan tahanan termal untuk pipa kalor dengan range beban kalor yang yang lebih luas, FR 60% menghasilkan kinerja terbaik dibandingkan FR 80% dan FR 40%.      


2020 ◽  
Vol 4 (1) ◽  
pp. 1-6
Author(s):  
Mirian Nomura ◽  
Luan Soares da Silva ◽  
Matheus Vinicius Abadia Ventura ◽  
Estevam Matheus Costa ◽  
Muriel Silva Vilarinho ◽  
...  

The objective of this work was to evaluate the production of cherry tomatoes in protected environments composed of different photoselective screens. The work was conducted in June / July 2018. The treatments consist of different types of protected environments: open sky, black screen (mesh for 30% shade); white fabric (mesh for 20% shade); blue screen (mesh for 20% of shade) and red screen (mesh for 20% of shade). The experimental design was a randomized block with four replicates, ten plants per experimental plot. The following analyses were performed on cherry tomatoes: leaf number, stem diameter, shoot height, root length, total fresh matter, shoot fresh matter, fresh root matter, shoot dry matter, root, chlorophyll a and chlorophyll b. The black shading, white photoselective, blue photoselective and red photoselective screens did not influence the number of leaves, stem diameter, shoot height, root length, total fresh matter, fresh shoot matter, aerial shoot dry matter, root dry matter, chlorophyll a and chlorophyll b. The red photoselective screen showed superiority in the fresh matter of the root of the other treatments.


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