scholarly journals Kajian Performansi Pompa Slurry pada Cutter Suction Dredger dengan Variasi Sudut Gali 35°, 40° dan 45°

2018 ◽  
Vol 1 (1) ◽  
pp. 028-033
Author(s):  
Asybel Bonar ◽  
Tekad Sitepu
Keyword(s):  
Cross Sectional Area ◽  
Piping System ◽  
Sectional Area ◽  
Cross Sectional ◽  
Carrier Medium ◽  
Flow Capacity ◽  
Piping Networks ◽  
Filtration Unit ◽  
Offshore Mining

Cutter Suction Dredger adalah salah satu metode penambangan lepas pantai. Untuk mendistribuskan material tambang dari dasar laut menuju unit penyaringan, digunakan air sebagai media pembawa dibantu dengan pompa melalui jaringan pemipaan. Sistem pemipaan merupakan bagian yang sangat penting dalam menyalurkan fluida. Dalam pengoperasiannya didapat kerugian yang menimbulkan beban tambahan yang ditimbulkan oleh gesekan antara fluida dan padatan denga pipa beserta dengan komponennya.Dalam penelitian ini, peneliti melakukan perhitungan head secara teoritis dimana prosedur dimulai dengan pengumpulan data data pendukung, kemudian melakukan perhitungan untuk mendapatkan hasil. Dalam kondisi lapangan, didapat terdapat perubahan luas penampang pipa dikarenakan oleh gesekan . Untuk menghitung head, digunakan persamaan Bernoulli, untuk kerugian head major dan head minor digunakan persamaan Darcy-Weisbach dimana kapasitas aliran adalah tetap sebesar 250 m3/h solid insitu dengan variasi sudut gali 25°,35°, dan 45° pada luas penampang dengan pemakaian baru, 1 bulan, 2 bulan, dan 3 bulan. Didapat besar head untuk setiap sudut secara berurutan adalah 399 rpm, 414.762 rpm, dan 433.984 rpm untuk pemakaian baru, 398.808 rpm, 413.987 rpm, 432.713 rpm untuk pemakaian 1 bulan, 397.368 rpm, 412.888 rpm, 428.125 rpm untuk pemakaian 2 bulan, dan 395.263 rpm, 411.021 rpm, 420.069 rpm untuk pemakaian 3 bulan.   Cutter Suction Dredger is an offshore mining method. Water is used as a carrier medium to distribute mining material from the seafloor to the filtration unit, by pump through piping networks. Piping system is a very important part in channeling fluid. In the operation, the loss is obtained because of the additional burdens caused by friction between fluid and solid with pipe along with its components. In this study, researcher conducted theoretical head calculations where the procedure started by collecting supporting data, then calculated it to get results. In field conditions, it was found that there was a change in cross-sectional area of ​​the pipe due to friction. Bernoulli equation was used to calculate head, Darcy-Weisbach equation was used for loss of major head and head minor where flow capacity was fixed at 250 m3/h solid in situ with variation of digging angle were 25 °, 35 °, and 45 ° on cross-sectional area for new, 1 month, 2 months and 3 months usage. The head sizes for each angle sequentially were 399 rpm, 414,762 rpm and 433,984 rpm for new usage; 398,808 rpm, 413,987 rpm, 432,713 rpm for 1 month usage; 397,368 rpm, 412,888 rpm, 428,128 rpm, 428,125 rpm for 2 months usage; and 395,263 rpm, 411,021 rpm, 420,069 rpm for 3 months usage.

scholarly journals Analisa Titik Operasi Optimum Pompa Slurry pada Bucket Wheel Dredger dengan Variasi Sudut Gali 30°, 35° dan 40°

2018 ◽  
Vol 1 (1) ◽  
pp. 034-039
Author(s):  
Robby Christian ◽  
Tekad Sitepu
Keyword(s):  
Optimum Operating ◽  
Cross Sectional ◽  
Mining Company ◽  
Flow Capacity ◽  
Operating Process ◽  
Piping Networks ◽  
Tin Metal ◽  
Filtration Unit ◽  
Optimum Operating Point ◽  
Offshore Mining

PT.Timah (Persero) Tbk. merupakan perusahaan tambang timah dengan cadangan terbesar di dunia yang menggunakan kapal isap tipe Bucket Wheel Dredger sebagai salah satu metode penambangan lepas pantai. Untuk mendistribuskan material tambang dari dasar laut menuju unit penyaringan, digunakan air sebagai media pembawa dibantu dengan pompa melalui jaringan pemipaan. Pada proses pengerukan, ternyata didapat masih ada material logam timah yang tertinggal di dasar lautan. Hal ini menyebabkan pengerukan menjadi kurang maksimal. Oleh karena itu, diperlukan analisa untuk mencari kondisi operasi optimum untuk setiap kedalaman penggalian. Dalam penelitian ini, dilakukan perhitungan head secara teoritis dimana prosedur dimulai dengan pengumpulan data pendukung, kemudian melakukan perhitungan untuk mendapatkan hasil. Dalam kondisi lapangan, didapat perubahan luas penampang pipa dikarenakan erosi. Untuk menghitung head, digunakan persamaan Bernoulli, untuk kerugian head major dan head minor digunakan persamaan Darcy-Weisbach dimana kapasitas aliran adalah tetap 7747.2 m3/h dengan variasi sudut gali 30°,35°, dan 40° pada luas penampang dengan pemakaian baru, 1 bulan, 2 bulan, dan 3 bulan. Didapat titik operasi optimum pompa slurry untuk setiap sudut secara berurutan adalah pada 517.08 rpm, 517.44 rpm, 520.96 rpm untuk pemakaian baru; 517.44 rpm, 517.44 rpm, 521.664 rpm untuk pemakaian satu bulan ; 517.44 rpm, 517.792 rpm, 520.96 rpm untuk pemakaian dua bulan; 511.808 rpm, 512.16 rpm, 513.92 rpm untuk tiga bulan.   PT. Timah (Persero) Tbk. is the largest tin mining company in the world which uses suction ships of Bucket Wheel Dredger as one of the offshore mining methods. Water is used as a carrier medium to distribute mining materials from seafloor to the filtration unit by pumps through piping networks. During the dredging process, it is found there is still tin metal material left on the ocean floor. This causes dredging process is less optimal. Based on the condition, it needed an analysis to find optimum operating process for each excavation depth. In this research, theoretical head calculations were carried out where the procedure began with supporting data collection, then calculated it to get results. In field conditions, changes in pipe cross section were obtained due to erosion. The Bernoulli equation was used to calculate head, Darcy-Weisbach equation was used for the loss of major and minor head where the flow capacity was fixed at 7747.2 m3/h with digging angle variations of 30 °, 35 °, and 40 ° in the cross-sectional area for new, 1 month, 2 months and 3 months usage. The optimum operating point of the slurry pump for each angles were obtained at 517.08 rpm, 517.44 rpm, 520.96 rpm for new usage; 517.44 rpm, 517.44 rpm, 521,664 rpm for one month usage; 517.44 rpm, 517,792 rpm, 520.96 rpm for two months usage; and 511,808 rpm, 512.16 rpm, 513.92 rpm for three months usage.

Nasal vestibule wall elasticity: interactions with a nasal dilator strip

1999 ◽  
Vol 86 (5) ◽  
pp. 1638-1643 ◽  
Author(s):  
T. C. Amis ◽  
J. P. Kirkness ◽  
E. di Somma ◽  
J. R. Wheatley
Keyword(s):  
Elastic Properties ◽  
Cross Sectional Area ◽  
Horizontal Direction ◽  
Sectional Area ◽  
Cross Sectional ◽  
Nasal Vestibule ◽  
Wall Displacement ◽  
Recoil Force ◽  
Wall Compliance

We studied the effect of an adhesive external nasal dilator strip (ENDS) on external nasal geometry in 20 healthy Caucasian adults (10 men, 10 women; age 21–45 yr). The recoil force exerted by ENDS was estimated by bending the device ( n = 10) with known weights. In the horizontal direction, a small/medium-sized ENDS in situ exerted a unilateral recoil force of 21.4–22.6 g. Application of ENDS resulted in a displacement of the lateral nasal vestibule walls that had both anterosuperior and horizontal components and that was maintained over an 8-h period. The resultant unilateral nasal vestibule wall displacement at the tip of the device was at 47.6 ± 2.0° to the horizontal (as related to the plane of the device when in situ) and had a magnitude of 3.5 ± 0.1 mm. ENDS increased external nasal cross-sectional area by 23.0–65.3 mm2. Nasal vestibule wall compliance was estimated at 0.05–0.16 mm/g. Thus ENDS applies a relatively constant abducting force irrespective of nasal width. Variable responsiveness to ENDS may be related to differences in elastic properties of the nasal vestibule wall.

scholarly journals Mass of different snow crystal shapes derived from fall speed measurements

2021 ◽  
Author(s):  
Sandra Vázquez-Martín ◽  
Thomas Kuhn ◽  
Salomon Eliasson
Keyword(s):  
Particle Size ◽  
Climate Models ◽  
Cross Sectional Area ◽  
Particle Mass ◽  
Sectional Area ◽  
Cross Sectional ◽  
Microphysical Properties ◽  
Ice Particles ◽  
Fall Speed

Abstract. Meteorological forecast and climate models require good knowledge of the microphysical properties of hydrometeors and the atmospheric snow and ice crystals in clouds. For instance, their size, cross-sectional area, shape, mass, and fall speed. Especially shape is an important parameter in that it strongly affects the scattering properties of ice particles, and consequently their response to remote sensing techniques. The fall speed and mass of ice particles are other important parameters both for numerical forecast models and for the representation of snow and ice clouds in climate models. In the case of fall speed, it is responsible for the rate of removal of ice from these models. The particle mass is a key quantity that connects the cloud microphysical properties to radiative properties. Using an empirical relationship between the dimensionless Reynolds and Best numbers, fall speed and mass can be derived from each other if particle size and cross-sectional area are also known. In this work, ground-based in-situ measurements of snow particle microphysical properties are used to analyse mass as a function of shape and the other properties particle size, cross-sectional area, and fall speed. The measurements for this study were done in Kiruna, Sweden during snowfall seasons of 2014 to 2019 and using the ground-based in-situ instrument Dual Ice Crystal Imager (D-ICI), which takes high-resolution side- and top-view images of natural hydrometeors. From these images, particle size (maximum dimension), cross-sectional area, and fall speed of individual particles are determined. The particles are shape classified according to the scheme presented in our previous work, in which particles sort into 15 different shape groups depending on their shape and morphology. Particle masses of individual ice particles are estimated from measured particle size, cross-sectional area, and fall speed. The selected dataset covers sizes from about 0.1 mm to 3.2 mm, fall speeds from 0.1 m s−1 to 1.6 m s−1, and masses from close to 0.2 μg to 320 μg. In our previous work, the fall speed relationships between particle size and cross-sectional area were studied. In this work, the same dataset is used to determine the particle mass, and consequently, the mass relationships between particle size, cross-sectional area, and fall speed are studied for these 15 shape groups. Furthermore, the mass relationships presented in this study are compared with the previous studies.

Determination of cross-sectional area of natural plant fibres and fibre failure analysis by in situ SEM observation during microtensile tests

Cellulose ◽  
2019 ◽  
Vol 26 (8) ◽  
pp. 4693-4706 ◽  
Author(s):  
Hangbo Yue ◽  
Juan C. Rubalcaba ◽  
Yingde Cui ◽  
Juan P. Fernández-Blázquez ◽  
Chufen Yang ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Natural Plant ◽  
Fibre Failure ◽  
Sem Observation

Influence of site of tracheal pressure measurement on in situ estimation of endotracheal tube resistance

1994 ◽  
Vol 77 (6) ◽  
pp. 2899-2906 ◽  
Author(s):  
P. Navalesi ◽  
P. Hernandez ◽  
D. Laporta ◽  
J. S. Landry ◽  
F. Maltais ◽  
...  
Keyword(s):  
Endotracheal Tube ◽  
Fluid Dynamic ◽  
Reference Value ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Tracheal Pressure

In situ measurement of distal tracheal pressure (Ptr) via an intraluminal side-hole catheter (IC) has been used to determine endotracheal tube (Rett) and intrinsic patient (Rpt) resistances in intubated subjects. Because of differences in cross-sectional area between the endotracheal tube (ETT) and trachea, fluid dynamic principles predict that IC position should critically influence these results. Accordingly, the aim of this study was to determine the effect of IC position on Rett. Ptr was recorded in vitro through an IC from 2 cm inside, at the tip of, or 2 cm outside an ETT (7, 8, and 9 mm ID) situated within an artificial trachea (13, 18, and 22 mm ID). A reference value of Rett was also obtained. Results were unaffected by IC position during inspiration, overestimating Rett by 7.9 +/- 0.7% (SE). In contrast, during expiration, Rett fell as IC position changed from outside to inside the ETT and was underestimated by 41.3 +/- 3.6% with Ptr recorded inside the ETT. Varying ETT or tracheal size had little effect on the relative error in Rett. The IC itself did increase Rett due to a reduction in effective cross-sectional area, the change varying directly with IC size and inversely with ETT caliber. In vivo values in 11 intubated patients were comparable to in vitro results. In summary, IC position and size can have important consequences on in situ measurements of Ptr and should be considered when clinically monitoring Rett or Rpt.

Effect of passive myocardium on the compliance of porcine coronary arteries

2003 ◽  
Vol 285 (2) ◽  
pp. H653-H660 ◽  
Author(s):  
Leila H. Hamza ◽  
Quang Dang ◽  
Xiao Lu ◽  
Ayesha Mian ◽  
Sabee Molloi ◽  
...  
Keyword(s):  
Coronary Arteries ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Arterial Tree ◽  
Cross Sectional ◽  
Video Densitometry ◽  
Relationship Of ◽  
Intravascular Pressure

The objective of this study was to determine the effect of passive myocardium on the coronary arteries under distension and compression. To simulate distension and compression, we placed a diastolic-arrested heart in a Lucite box, where both the intravascular pressure and external (box) pressure were varied independently and expressed as a pressure difference (ΔP = intravascular pressure – box pressure). The ΔP-cross-sectional area relationship of the first several generations of porcine coronary arteries and the ΔP-volume relationship of the coronary arterial tree (vessels >0.5 mm in diameter) were determined using a video densitometric technique in the range of +150 to –150 mmHg. The vasodilated left anterior descending (LAD) coronary artery of six KCl-arrested hearts were perfused with iodine and 3% Cab-O-Sil. The intravascular pressure was varied in a triangular pattern, whereas the absolute cross-sectional area of each vessel and the total arterial volume were calculated using video densitometry under different box pressures (0, 50, 100, and 150 mmHg). In the range of positive ΔP, we found that the compliance of the proximal LAD artery in situ (4.85 ± 3.8 × 10–3 mm2/mmHg) is smaller than that of the same artery in vitro (16.5 ± 6 × 10–3 mm2/mmHg; P = 0.009). Hence, the myocardium restricts the compliance of the epicardial artery under distension. In the negative ΔP range, the LAD artery does not collapse, whereas the same vessel readily collapses when tested in vitro. Hence, we conclude that myocardial tethering prevents collapse of large blood vessel under compression.

A New Method of Measuring the Cross-Sectional Area of Connective Tissue Structures

1988 ◽  
Vol 110 (2) ◽  
pp. 104-109 ◽  
Author(s):  
N. G. Shrive ◽  
T. C. Lam ◽  
E. Damson ◽  
C. B. Frank
Keyword(s):  
Cross Section ◽  
Rectangular Cross Section ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Connective Tissues ◽  
Maximum Width ◽  
Cross Sectional ◽  
Elliptical Cross ◽  
The Cross

There appears to be no generally accepted method of measuring in-situ the cross-sectional area of connective tissues, particularly small ones, before mechanical testing. An instrument has therefore been devised to measure the cross-sectional area of one such tissue, the rabbit medial collateral ligament, directly and nondestructively. However, the methodology is general and could be applied to other tissues with appropriate changes in detail. The concept employed in the instrument is to measure the thickness of the tissue as a function of position along the width of the tissue. The plot obtained of thickness versus width position is integrated to provide the cross-sectional area. This area is accurate to within 5 percent, depending mainly on alignment of the instrument and pre-load of the ligament. Results on the mid-substance of the rabbit medial collateral ligaments are repeatable and reproducible. Values of maximum width and thickness are less variable than those obtained with a vernier caliper. The measured area is considerably less than that estimated assuming rectangular cross-section and slightly less than that estimated on the assumption of elliptical cross-section.

A method for measurement of cross sectional area, segment length, and branching angle of airway tree structures in situ

1995 ◽  
Vol 19 (1) ◽  
pp. 145-152 ◽  
Author(s):  
Susan A. Wood ◽  
John D. Hoford ◽  
Eric A. Hoffman ◽  
Elias Zerhouni ◽  
Wayne Mitzner
Keyword(s):  
Cross Sectional Area ◽  
Segment Length ◽  
Sectional Area ◽  
Cross Sectional ◽  
Tree Structures ◽  
Branching Angle ◽  
Airway Tree

scholarly journals Shape dependence of snow crystal fall speed

2021 ◽  
Vol 21 (10) ◽  
pp. 7545-7565
Author(s):  
Sandra Vázquez-Martín ◽  
Thomas Kuhn ◽  
Salomon Eliasson
Keyword(s):  
Particle Size ◽  
Numerical Models ◽  
Area Ratio ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Maximum Dimension ◽  
Cross Sectional ◽  
Ice Particles ◽  
Fall Speed

Abstract. Improved snowfall predictions require accurate knowledge of the properties of ice crystals and snow particles, such as their size, cross-sectional area, shape, and fall speed. The fall speed of ice particles is a critical parameter for the representation of ice clouds and snow in atmospheric numerical models, as it determines the rate of removal of ice from the modelled clouds. Fall speed is also required for snowfall predictions alongside other properties such as ice particle size, cross-sectional area, and shape. For example, shape is important as it strongly influences the scattering properties of these ice particles and thus their response to remote sensing techniques. This work analyzes fall speed as a function of particle size (maximum dimension), cross-sectional area, and shape using ground-based in situ measurements. The measurements for this study were done in Kiruna, Sweden, during the snowfall seasons of 2014 to 2019, using the ground-based in situ instrument Dual Ice Crystal Imager (D-ICI). The resulting data consist of high-resolution images of falling hydrometeors from two viewing geometries that are used to determine particle size (maximum dimension), cross-sectional area, area ratio, orientation, and the fall speed of individual particles. The selected dataset covers sizes from about 0.06 to 3.2 mm and fall speeds from 0.06 to 1.6 m s−1. Relationships between particle size, cross-sectional area, and fall speed are studied for different shapes. The data show in general low correlations to fitted fall speed relationships due to large spread observed in fall speed. After binning the data according to size or cross-sectional area, correlations improve, and we can report reliable parameterizations of fall speed vs. particle size or cross-sectional area for part of the shapes. For most of these shapes, the fall speed is better correlated with cross-sectional area than with particle size. The effects of orientation and area ratio on the fall speed are also studied, and measurements show that vertically oriented particles fall faster on average. However, most particles for which orientation can be defined fall horizontally.

Sign in / Sign up

Export Citation Format

Share Document