A comparison of wood-sediment-water mixture flows at a closed type and an open type of check dams in mountain rivers

2014 ◽  
pp. 711-716 ◽  
Author(s):  
F Maricar ◽  
H Hashimoto
Keyword(s):  
Water Mixture ◽  
Mountain Rivers ◽  
Open Type ◽  
Check Dams ◽  
Closed Type

scholarly journals Analysis of Debris Flow Reduction Effect of Check Dam Types considering the Mountain Stream Shape: A Case Study of 2016 Debris Flow Hazard in Ulleung-do Island, South Korea

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Man-Il Kim ◽  
Namgyun Kim
Keyword(s):  
South Korea ◽  
Debris Flow ◽  
Observation Point ◽  
Mountain Stream ◽  
Check Dam ◽  
Open Type ◽  
Flow Reduction ◽  
Check Dams ◽  
Closed Type ◽  
Type Check

Ulleung-do is a volcanic island located 130 km east of the Gangwon-do province of South Korea. It is characterized by steep slopes covered with effusive rocks released from multiple volcanic activities. Having accumulated deep colluvium, Ulleung-do Island manifests a high vulnerability to landslides frequently caused by heavy rains or typhoons, debris flow, rockfall, and other disaster hazards in mountainous areas. Therefore, facilities and residential areas located in the lower areas of the island sustain widespread damage. Hence, the installation of check dams designed to reflect the area’s local conditions is required to avoid further damage. In line with that, this study analyzes the disaster cases in Ulleung-do’s mountain areas and the effect of check dams in debris flow reduction for each type using the KANAKO-2D model. At observation point 1, the result shows that the maximum rate of debris flow is reduced by 48.5% with an open-type check dam installed and 62.9% with a closed-type check dam installed from the level without a check dam. For observation point 2, the maximum flow depth decreases by 49.7% with an open-type check dam and 77.4% with a closed-type check dam. Thus, this study suggests that the simple installation of check dams in a mountain stream that has experienced debris flow effectively mitigates damage brought by various disasters.

Design Standard of Control Structures Against Debris Flow in Japan

2010 ◽  
Vol 5 (3) ◽  
pp. 307-314 ◽  
Author(s):  
Nobutomo Osanai ◽  
◽  
Hideaki Mizuno ◽  
Takahisa Mizuyama ◽  
Keyword(s):  
Debris Flow ◽  
Flow Control ◽  
Warning Systems ◽  
Technical Standard ◽  
Stone Size ◽  
Control Structures ◽  
Open Type ◽  
Check Dams ◽  
Closed Type ◽  
Structural Measures

Countermeasures to prevent or mitigate sedimentrelated hazards, debris flow in this paper are classified as structural measures or nonstructural measures. The structural measures are Sabo dams, leading dikes, and channels for debris flow control. The nonstructural measures are the designation of areas prone to debris flow, proper land use in the areas, the reinforcement of houses, the creation of warning systems and the evacuation of the inhabitants in case of emergency. A technical standard on debris flow control structures of Japan was revised in 2007. Major revision is that check dams called Sabo dams constructed near houses are changed from closed type Sabo dams to open type Sabo dams because the occurrence frequency is low as once for longer than one hundred years, natural torrent environment should be conserved in ordinary days and sediment trap capacity should be kept until debris flow occurs. Points changed are explained such as the opening of open type dams is as equal as the maximum stone size.

scholarly journals Numerical and Experimental Study of the Impeller of a Liquid Pump of a Truck Cooling System and the Development of a New Open-Type Impeller

2020 ◽  
Vol 14 (2) ◽  
pp. 135-142
Author(s):  
Rishat Salakhov ◽  
Andrey Ermakov ◽  
Elvira Gabdulkhakova
Keyword(s):  
Cooling System ◽  
Cost Effective ◽  
Pump Efficiency ◽  
Numerical Computations ◽  
Open Type ◽  
Maximum Value ◽  
Closed Type ◽  
Ansys Cfx ◽  
Wheel Model ◽  
Liquid Pump

Typically, closed-type impellers are more efficient than open-type impellers, but in the manufacture of closed-type impellers, cost of wheels is higher. This paper describes the development of cost-effective and simple impeller wheel for a fluid pump in the truck cooling system. To perform this task, the numerical computations of a standard impeller wheel were carried out, its characteristics were also obtained from a test bench, the standard impeller wheel model was verified. The open-type impeller wheel was developed according to the current dimensions of standard impeller wheel and then analyzed with the numerical computations by the software ANSYS CFX (Academic license) computational fluid dynamics. The developed open-type impeller wheel works very effectively in spite of performance degradation by 5% in comparison to the closed-type impeller wheel. When working as a part of engine, the pump efficiency is 0.552-0.579. The maximum value of the pump efficiency is 0.579, it can be achieved at the highest speed of the pump (4,548 rpm and 655 l/min).

Performance of Adsorptive Heat Storage Devices for Heat Supply

2021 ◽  
pp. 124-173
Keyword(s):  
Silica Gel ◽  
Heat Supply ◽  
Heat Storage ◽  
Sodium Sulphate ◽  
Storage Device ◽  
Efficiency Coefficient ◽  
Composite Adsorbent ◽  
Open Type ◽  
Storage Devices ◽  
Closed Type

The chapter is focused on modelling of performance of adsorptive heat storage devices and estimation of performance of heat storage devices. Two groups of models of adsorptive heat storage units suggested previous researchers are analyzed. The first one is focused on predicting the heat energy storage density, it being based on Dubinin-Polanyi theory. The second one is devoted to analyzing the kinetic of adsorption processes and performance of the adsorber or adsorptive-desorptive reactor filled with traditional adsorbent or salt which forms crystalline hydrates. The key drawback of both groups of models concerns with considering only one stage of exploitation of adsorptive heat storage device in spite of its operating in two-stage mode, that is, alternating discharge (adsorption) and charge (regeneration). It inhibits estimation of efficiency of adsorptive heat storage device basing on full operating cycle and its involving in heat supply system. Two algorithms for estimation of operating parameters are proposed by authors for closed-type and open-type heat storage devices. The algorithm for calculation of operating parameters of closed type adsorptive heat storage device is proposed: calculation of the mass transfer coefficient, adsorption, useful heat, that is, heat of adsorption, determination of the heat input, it being calculated as heat inputs for heating the adsorbent, device housing, water in the tank, evaporation of water in the tank, heating of the adsorbed water and desorption. Then efficiency factor is calculated. The operating characteristics of a closed-type heat energy storage device were studied when the composite adsorbent ‘silica gel – sodium sulphate' used. The effect of the humid airflow velocity on the efficiency factor is taken into account by introducing a coefficient equal to the value of the adsorption. An increase in the efficiency coefficient was stated when the velocity and relative humidity of the airflow. It is shown that the humid air flow temperature practically does not affect its value. Having been used the suggested algorithm, the optimal operating characteristics of an adsorptive heat storage device of a closed type based on a composite adsorbent ‘silica gel – sodium sulphate' for a private house heating system are revealed to be humid air velocities of 0.6 – 0.8 m/s and relative humidity 40 – 60%. When these operational data applied, the efficiency coefficient is shown to reach the maximum values (about 55%). Algorithm of calculation of operating parameter of open-type heat storage device includes computation of mass transfer coefficient, adsorption, useful heat (heat of adsorption), heat input for heating the adsorbent, device casing, water in the humidifier, evaporation of water, heating the adsorbed water, desorption, and calculating efficiency coefficient. Performance of open-type heat storage device based on the composite adsorbent ‘silica gel – sodium sulphate' is estimated. The optimal operating conditions of the heat accumulating device which allow operating with maximal magnitudes of efficiency coefficients 53 – 57% are stated to be humid airflow speed of 0.6 – 0.8 m/s and relative humidity of 40 – 60%. Correlation between efficiency factors obtained by experiments and calculated with suggested algorithm is confirmed. The possibility of reducing the power consumption when heat storage devices applied in 2,4 – 90 times versus decentralized heating systems on basis of solid fuel boiler, gas boiler and electric boiler is stated when open-type sorptive heat storage device used. Results of the study can be used to develop adsorptive storage devices in decentralized heat supply and ventilation systems and adsorption units for utilization of low-temperature waste heat.

Effect of Curvilinear Element Blade for Open-Type Centrifugal Impeller on Stator Performance

2019 ◽  
Author(s):  
Kazuhiro Tsukamoto ◽  
Kiyohide Sakamoto ◽  
Kiyotaka Hiradate ◽  
Yasushi Shinkawa
Keyword(s):  
Rotating Stall ◽  
Centrifugal Impeller ◽  
Parameter Study ◽  
Tip Leakage Flow ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Open Type ◽  
Closed Type ◽  
Key Techniques ◽  
Stage Efficiency

Abstract The effect of a curvilinear element blade for an open-type centrifugal impeller on stator performance was investigated by experiment using an actual single stage compressor. This investigation focused on the stator part performance located at the downstream of the impeller for both a vane-less diffuser and a vaned diffuser. Centrifugal compressors are widely used in various industrial plants, and some customers require higher stage performance. The curvilinear element blade technique, which is one of the key techniques for increasing the efficiency of closed-type centrifugal impellers, was investigated, and it effected an increase in stator efficiency. For this reason, the effect of the curvilinear element blade for the open-type centrifugal impeller was investigated. Our previous study reported that the curvilinear element blade with the open-type impeller increased the impeller efficiency by decreasing the loss derived from the impeller tip leakage flow with the parameter study of the curvilinear element blade geometries using numerical simulations. This paper reports the results of the experimental verifications using the geometries from the previous report. Experimental results indicated that the compressor stage efficiency increased by 0.7% compared with that of the conventional impeller, which has a linear element blade by using the vane-less diffuser. However, a rotating stall occurred at a higher flow rate than that of the conventional case in the vane-less diffuser. This is due to the decrease of the impeller outlet flow angle derived from the effect of the curvilinear element blade, which makes the velocity distribution equal and reduces the blockage regions near the shroud side. On the other hand, the curvilinear element blade impeller could increase the stage efficiency by 1.2% over the conventional impeller by using the vaned diffuser. This is due to not only the impeller performance increase but also the diffuser performance increase derived from the equality of the flow distributions by the curvilinear element blade. In addition, there was no diffuser rotating stall.

scholarly journals A Comparative Study of the Fitness and Trueness of a Three-Unit Fixed Dental Prosthesis Fabricated Using Two Digital Workflows

2019 ◽  
Vol 9 (14) ◽  
pp. 2778 ◽  
Author(s):  
Daehee Jang ◽  
Keunbada Son ◽  
Kyu-bok Lee
Keyword(s):  
Pearson Correlation ◽  
Dental Prosthesis ◽  
Test Model ◽  
3D Analysis ◽  
Digital Workflow ◽  
Open Type ◽  
Fixed Dental Prosthesis ◽  
Closed Type ◽  
Computer Aided ◽  
Internal Fit

The purpose of this study was to measure and correlate the fitness and trueness of a 3-unit fixed dental prosthesis (FDP) fabricated using two digital workflows. The 3-unit FDPs were fabricated using two digital workflows (N = 15). The digital workflows were divided into chairside (closed type) and in-lab (open type) groups. The scanning, computer-aided design (CAD), and computer-aided manufacturing (CAM) processes were conducted with 3shape E1 scanner, exocad CAD software, and DDS EZIS HM, respectively, in the in-lab group; and with CEREC omnicam intraoral scanner, CEREC CAD software, and CEREC MC XL, respectively, in the chairside group. The fitness of the fabricated 3-unit FDPs was evaluated by scanning the silicone replica of the cement space and analyzing the thickness of the silicone replica in the three-dimensional (3D) inspection software (Geomagic control X). The trueness of the milling unit was analyzed by 3D analysis of the CAD reference model, which is the design file of the 3-unit FDP, and the CAD test model, which is the scanned file of the 3-unit FDP. In the statistical analysis, comparison of the two groups was conducted by Mann–Whitney U test, and the correlation between the fitness and trueness was conducted by Pearson correlation test (α = 0.05). The marginal and internal fit were significantly lower in the in-lab group at all measurement positions (p < 0.001). The trueness of the milling unit was significantly higher in the in-lab group compared to the chairside group (p < 0.001). There was a positive correlation between the trueness and internal fit (correlation coefficient = 0.621) in the in-lab group (p = 0.013). The use of appropriate equipment in an in-lab (open type) digital workflow enables a better fabrication of 3-unit FDPs than a chairside (closed type) digital workflow, and poor trueness on the inner surface of the crown adversely affects the internal fit.

An Evaluation of Teaching Techniques Used in Transkei, South Africa to Assess Competency in Primary Mathematics

1995 ◽  
Vol 76 (3) ◽  
pp. 747-754 ◽  
Author(s):  
John Oliver ◽  
Michael J. Glencross
Keyword(s):  
South Africa ◽  
Mathematics Curriculum ◽  
Participant Observation ◽  
Classroom Observation ◽  
Teaching Techniques ◽  
Open Type ◽  
Primary Mathematics ◽  
Grade 5 ◽  
Closed Type ◽  
Evaluation Of Teaching

To evaluate the suitability of the senior primary mathematics curriculum in Transkei, South Africa in enabling Standard 3 (Grade 5) and Standard 4 (Grade 6) pupils to achieve competency in mathematics, an overview of teaching techniques was obtained using participant observation and class teaching exercises. Analysis showed that teachers relied largely on closed-type teaching techniques and heavily on textbooks, while direct classroom observation indicated teachers' lack of ability to innovate and make teaching topical and dynamic. The pupils were generally unable to solve open-type questions, a situation attributed here to the teachers' rigid pattern of teaching.

Localization of acyl ghrelin- and des-acyl ghrelin-immunoreactive cells in the rat stomach and their responses to intragastric pH

2009 ◽  
Vol 297 (5) ◽  
pp. G974-G980 ◽  
Author(s):  
Makoto Mizutani ◽  
Kaori Atsuchi ◽  
Akihiro Asakawa ◽  
Norifumi Matsuda ◽  
Masaki Fujimura ◽  
...  
Keyword(s):  
The Other ◽  
Antral Mucosa ◽  
Intragastric Ph ◽  
Double Staining ◽  
Rat Stomach ◽  
Acid Modification ◽  
Oxyntic Mucosa ◽  
Open Type ◽  
Closed Type ◽  
Acyl Ghrelin

Acyl ghrelin has a 28-amino acid sequence with O-n-octanoyl acid modification at the serine 3 position, whereas des-acyl ghrelin has no octanoyl acid modification. Although these peptides exert different physiological functions, no previous studies have shown the different localization of acyl ghrelin and des-acyl ghrelin in the stomach. Here we have developed an antibody specific for des-acyl ghrelin that does not crossreact with acyl ghrelin. Both acyl ghrelin- and des-acyl ghrelin-immunoreactive cells were distributed in the oxyntic and antral mucosa of the rat stomach, with higher density in the antral mucosa than oxyntic mucosa. Immunofluorescence double staining showed that acyl ghrelin- and des-acyl ghrelin-positive reactions overlapped in closed-type round cells, whereas des-acyl ghrelin-positive reaction was found in open-type cells in which acyl ghrelin was negative. Acyl ghrelin-/des-acyl ghrelin-positive closed-type cells contain obestatin; on the other hand, des-acyl ghrelin-positive open-type cells contain somatostatin. We measured the release of acyl ghrelin and des-acyl ghrelin in vascularly perfused rat stomach by ELISA, and the effects of different intragastric pH levels on the release of each peptide were examined. The release of des-acyl ghrelin from the perfused stomach was greater at pH 2 than at pH 4; however, the release of acyl ghrelin was not affected by intragastric pH. The present study demonstrated the differential localization of acyl ghrelin and des-acyl ghrelin in the rat stomach and their different responses to the intragastric pH.

scholarly journals Participles in contrast

2014 ◽  
Vol 6 (1) ◽  
Author(s):  
Hans Petter Helland ◽  
Anneliese Pitz
Keyword(s):  
Structural Analysis ◽  
Structural Properties ◽  
The Other ◽  
Open Type ◽  
Crucial Difference ◽  
Closed Type ◽  
The One

In this paper, we propose a structural analysis of present and past participles in two constructions: open and closed adjuncts. The crucial difference between the two types of adjuncts to be accounted for concerns the availability of an explicit (for the closed type) or an implicit (for the open type) DP subject. Our analysis is based on data from French and German in the OMC corpus. These data allow us on the one hand to identify the idiosyncratic properties of the constructions in the two languages, and on the other to test our hypotheses concerning the structural properties of the various participial constructions in a cross-linugistic perspective.

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