head height
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2021 ◽  
Vol 14 (2) ◽  
pp. 99-105
Author(s):  
Ma'mun Abdul Karim ◽  
Jojo Sumarjo ◽  
Najmudin Fauji

The screw type water turbine is one type of water turbine that has the potential to generate electricity on a small scale that is environmentally friendly, where this screw type water turbine is very suitable for rivers and irrigation flows in the territory of Indonesia because the use or operation of this turbine only requires low turbine head, looking at the potential for irrigation river water flow with a discharge range of 0.01-0.1 m3/s located in the lowlands in a Karawang district, it is possible to install or apply this screw type water turbine. In this study aims to be able to utilize the source of irrigation flow so that it can be converted into a source of electrical energy that can be utilized by local residents and for lighting on roads that are still poorly lit. In the process of designing a screw type water turbine, mechanical calculations are carried out to determine thedimensions of the turbine blades, turbine shaft, transmission systems such as pulleys and belts, as well as the power that can be generated by the turbine, with a relative head between 0.5 meters, 0.75 meters, and 0.9 meters and determine the correct components. The results of this calculation are obtained in the form of output power from each different head height for head 0.5, the power obtained is 220.89795 watts, for the 0.75 m head, the power is 394.29519 watts, and for the height 0.9, the output power is 356.13926 watts, the results of the design will then be made and will be realized.


CATENA ◽  
2021 ◽  
Vol 207 ◽  
pp. 105674
Author(s):  
Rui Wang ◽  
Peng Li ◽  
Zhanbin Li ◽  
Kunxia Yu ◽  
Jianchun Han ◽  
...  

2021 ◽  
Vol 10 (6) ◽  
pp. 3167-3177
Author(s):  
Yuliana Susilowati ◽  
Pudji Irasari ◽  
Yugo Kumoro ◽  
Wawan Hendriawan Nur ◽  
Yunarto Yunarto

Remote sensing technology has been widely applied in various fields, including oil, gas, and mineral exploration, spatial planning, and environmental monitoring. This paper describes the application of remote sensing technology for the potential study of a renewable micro hydropower plant (MHP) using Landsat 8 satellite data. The Sukaati Watershed, West Java, Indonesia, was selected as the case study area. Landsat 8 satellite data, acquired on August 21, 2020, was applied to extract information on land use, geology, and potential landslides. Drainage patterns, watershed boundaries, and head height were obtained from topographic map data. Drainage patterns, watershed boundaries, and land use are used to calculate flow rates. Geological map and landslide are the basis of layout of MHP components, such as water intake, dam, waterway, settling tank, penstock, and powerhouse. A field survey to acquire actual flow rate and head height was conducted to validate the results of the remote sensing data interpretation. Two potential sites of MHP were selected with a hydropower design of 129 kW and 5.18 MW. This study showed that remote sensing technology is beneficial for studying the potential of MHP because fieldwork can be done more quickly and efficiently.


2021 ◽  
Author(s):  
Yifan Jiang ◽  
Ping Zhou ◽  
Feicong Zhou ◽  
Jiayong Lin ◽  
Jinyi Li ◽  
...  

Abstract Revealing the conditions for the occurrence of sand gushing accidents in tunnels with water-rich sandy dolomite strata can help the tunnels to be constructed safely. In this paper, we found that sandy dolomite and the water environment are the key factors causing sand surges through geophysical prospecting at the tunnel face where 12,000 m 3 sand surge occurred. Through the flow-solid coupling model, the extrusion deformation at the tunnel face is the main deformation form in the tunnel of water-rich sandy dolomite strata. The influence of different factors on the deformation value of the tunnel face is from strong to weak: sandification degree, head height, and tunnel depth. Combined with the study of pressure arch characteristics of the model, the limit equilibrium theory considering seepage effects and pressure arch characteristics is proposed. We get that sand surges will occur in the tunnel in the intensively sandy dolomite strata where the head exceeds 80m. For the intensively sandy dolomite strata with head below 80m, the stability of the tunnel face is controlled by the degree of seepage damage. According to the reason of sand gushing, the comprehensive control measures consisting of risk identification by over-detection, double-layer close-packed pipe shed, grouting sealing technology and dewatering technology, and Milling and blasting combined construction method are proposed, and the effective control of tunnel working face is realized in practical application.


2021 ◽  
Author(s):  
Xinghui Xu ◽  
Jun Li ◽  
Deping Yao ◽  
Pan Deng ◽  
Boliang Chen ◽  
...  

Abstract Objective: To investigate the correlation between fibular head height and the incidence and severity of varus knee osteoarthritis based on three-dimensional reconstruction of the knee joint.Methods: The data of knee joint imaging in our hospital from June 2018 to June 2020 were collected. The degree of varus deformity of the knee was assessed at the superior hip-knee-ankle angle of the X-rays. Three-dimensional reconstruction of patient computed tomography(CT)data was performed by mimics software. The fibular head height, joint line convergence angle (JLCA) and medial proximal tibial angle (MPTA) were measured in a three-dimensional model. The patients were divided according to the Kellgren-Lawrence grade: group A: grade 0, group B: grade I, group C: grade II, group D: grade III, and group E: grade IV. The differences in age, gender, height, weight, body mass index(BMI), fibular head height, and degree of varus deformity (JLCA, MPTA, and coxa-knee-ankle angle) were compared. Ordinal multivariate logistic regression was used to analyze the correlation between fibular head height and Kellgren-Lawrence grade.Pearson correlation was used to analyze the correlation between fibular head height and Kellgren-Lawrence grade.Results: 232 patients (232 knees) were finally included in the study, with Kellgren-Lawrence grades of 28 in group A, 31 in group B, 49 in group C, 53 in group D, and 71 in group E. The differences in age, gender, height, body mass index, fibular head height, JLCA, MPTA, and hip-knee-ankle angle among the five groups were statistically significant (P < 0.05), and the differences in body weight were not statistically significant (P > 0.05). There were significant differences in fibular head height, JLCA, JLCA and hip-knee-ankle angle between different groups (P < 0.05). Furthermore, there were significant differences in JLCA and hip-knee-ankle angle (P < 0.05), and both JLCA and hip-knee-ankle angle increased with severe aggravation of Kellgren-Lawrence grade. Furthermore, both fibular head height and MPTA decreased as the Kellgren-Lawrence grade was severely aggravated. There was a significant negative correlation between Kellgren-Lawrence grade and fibular head height (r = -0.812, P < 0.001). Furthermore, there was a significant negative correlation between fibular head height and hip-knee-ankle angle (r = -0.7905, P < 0.001). When Kellgren-Lawrence grade III and IV knees were considered as disease, ROC curve analysis showed a cut-off value of 10.63 for fibular head height and an AUC of 0.872.Conclusion: The height of fibular head in patients with varus knee osteoarthritis is smaller than that in non-osteoarthritis patients. In addition to body mass index, fibular head height is a risk factor for the pathogenesis of varus knee osteoarthritis,the smaller the fibular head height, the more severe the severity of osteoarthritis and the more severe the degree of varus deformity.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yulhyun Park ◽  
Jin Young Ko ◽  
Joon Young Jang ◽  
Seungeun Lee ◽  
Jaewon Beom ◽  
...  

AbstractThere have been many studies on adolescent idiopathic scoliosis related abnormal muscle contractions of the spine. However, previous studies using surface electromyography to investigate paraspinal muscle asymmetry are controversial, lacking in clarity of results, and hindered by methodological limitations. The purpose of this study was to investigate the relationship between imbalance factors including surface electromyography activity according to the scoliosis curve type and leg length discrepancy and adolescent idiopathic scoliosis curve types. Seventy-nine patients with scoliosis were prospectively enrolled and were divided into five types: single thoracic, thoracolumbar, lumbar, double thoracic, and double major. Cobb angle and structural variables were measured. Surface electromyography examinations were conducted at the 7th, 12th thoracic erector spinae, 3rd lumbar erector spinae, and multifidus muscles during the superman position keeping prone spinal extension to lift the arms and legs off the floor. Whole spine radiographs were obtained to measure the Cobb angle, coronal imbalance, pelvic height and angle, and femoral head height. In the double major, thoracolumbar, and lumbar types, the mean root mean squared (RMS) EMG amplitudes were significantly higher on the convex side than the concave side (P < 0.005). In the DM type, the mean RMS EMG amplitudes of EST7 and ESL3 where the apex was located were significantly higher at the convex side than those of the concave side (P < 0.005, effect size (Cohen’s d) for EST7/ESL3: 0.517/0.573). The TL and L types showed a similar pattern. The mean RMS EMG amplitudes of the EST12 concave side and MuL3 and ESL3 concave sides were significantly lower than those of the convex side in the TL and L types, respectively (P < 0.008, effect size (Cohen’s d) for EST12/MuL3/ESL3: 0.960/0.264/0.448). Conversely, there were no significant differences in the single thoracic and double thoracic types. All structural variables (coronal imbalance, pelvic height and angle, and femur head height) were higher in the lumbar type, but only coronal imbalance was significantly different (P < 0.05). Different patterns of asymmetry of paraspinal muscles and structural variables were described based on the curvature of the spine. L type showed that EMG activity was asymmetric in the paraspinalis muscles where the apex was located and that structural asymmetry, such as coronal imbalance was significantly greater than other types. DM type showed similar paraspinalis asymmetry pattern to the ST type but there was no structural asymmetry in DM and ST types. TL type has the features of both thoracic and lumbar origins. Understanding these could contribute to the management in correcting scoliosis.


Author(s):  
Daniel Tang ◽  
Mike Evans ◽  
Paul Briskham ◽  
Luca Susmel ◽  
Neil Sims

Self-pierce riveting (SPR) is a complex joining process where multiple layers of material are joined by creating a mechanical interlock via the simultaneous deformation of the inserted rivet and surrounding material. Due to the large number of variables which influence the resulting joint, finding the optimum process parameters has traditionally posed a challenge in the design of the process. Furthermore, there is a gap in knowledge regarding how changes made to the system may affect the produced joint. In this paper, a new system-level model of an inertia-based SPR system is proposed, consisting of a physics-based model of the riveting machine and an empirically-derived model of the joint. Model predictions are validated against extensive experimental data for multiple sets of input conditions, defined by the setting velocity, motor current limit and support frame type. The dynamics of the system and resulting head height of the joint are predicted to a high level of accuracy. Via a model-based case study, changes to the system are identified, which enable either the cycle time or energy consumption to be substantially reduced without compromising the overall quality of the produced joint. The predictive capabilities of the model may be leveraged to reduce the costs involved in the design and validation of SPR systems and processes.


2021 ◽  
Vol 22 (14) ◽  
pp. 7599
Author(s):  
Kara J. Turner ◽  
Eleanor M. Watson ◽  
Benjamin M. Skinner ◽  
Darren K. Griffin

Infertility is a problem affecting an increasing number of couples worldwide. Currently, marker tests for male factor infertility are complex, highly technical and relatively subjective. Up to 40% of cases of male factor infertility are currently diagnosed as idiopathic therefore, there is a clear need for further research into better ways of diagnosing it. Changes in sperm telomere length have been associated with infertility and closely linked to DNA damage and fragmentation, which are also known to be related to infertility. However, telomere distribution is a parameter thus far underexplored as an infertility marker. Here, we assessed morphological parameters of sperm nuclei in fertile control and male factor infertile cohorts. In addition, we used 2D and 3D fluorescence in situ hybridization (FISH) to compare telomere distribution between these two groups. Our findings indicate that the infertile cohort sperm nuclei were, on average, 2.9% larger in area and showed subtle differences in sperm head height and width. Telomeres were mainly distributed towards the periphery of the nuclei in the control cohort, with diminishing telomere signals towards the center of the nuclei. Sperm nuclei of infertile males, however, had more telomere signals towards the center of the nuclei, a finding supported by 3D imaging. We conclude that, with further development, both morphology and telomere distribution may prove useful investigative tools in the fertility clinic.


2021 ◽  
Author(s):  
Javad Mohammadi ◽  
Bahareh Pirzadeh ◽  
Gholamreza Azizyan ◽  
Azam Abdollahi

Abstract Researchers have recently shown interest in complex flow patterns, especially the effects of secondary flows, in a curved channel. This paper studied the obstacle effects in a gravity current in a channel with a symmetrical 120° bend using the OpenFoam toolbox and the Realizable k–ε turbulence model for simulation. The models studied included no-obstacle curved channel, curved channel with obstacle in 30° position, curved channel with obstacle in 60° position and curved channel with obstacle in 60° position with increased radius. Results showed that the obstacle directed the concentration towards the banks with its maximum value tending from the outer to the inner bank, especially in the tail. Although the post-obstacle head height did not change, that of the tail did (fell); the tail longitudinal velocity was maximized near the channel bed in areas far from the obstacle, and in the outer bank in areas near it. The secondary flow was so reduced that its lowest and most different pattern was observed around the obstacle. In displacing the latter, if the front was at a certain distance from it, the secondary flow did not change much, but if it was at the channel end, the post-obstacle secondary flow increased as the obstacle neared the lock.


2021 ◽  
Vol 8 ◽  
Author(s):  
Ashraf Ayoub ◽  
Leonardo de Freitas Silva ◽  
Peter Mossey ◽  
Dhelal Al-Rudainy ◽  
Adriana Marques de Mattos ◽  
...  

Background: This study was carried out in response to the Zika virus epidemic, which constituted a public health emergency, and to the 2019 WHO calling for strengthened surveillance for the early detection of related microcephaly. The main aim of the study was to phenotype the craniofacial morphology of microcephaly using a novel approach and new measurements, and relate the characteristics to brain abnormalities in Zika-infected infants in Brazil to improve clinical surveillance.Methods: 3D images of the face and the cranial vault of 44 Zika-infected infants and matched healthy controls were captured using a 3D stereophotogrammetry system. The CT scans of the brain of the infected infants were analysed. Principal component analysis (PCA) was applied to characterise the craniofacial morphology. In addition to the head circumference (HC), a new measurement, head height (HH), was introduced to measure the cranial vault. The level of brain abnormality present in the CT scans was assessed; the severity of parenchymal volume loss and ventriculomegaly was quantified. Student's t-test and Spearman's Rho statistical test have been applied.Findings: The PCA identified a significant difference (p &lt; 0.001) between the cranial vaults and the face of the Zika infants and that of the controls. Spearman's rank-order correlation coefficients show that the head height (HH) has a strong correlation (0.87 in Zika infants; 0.82 in controls) with the morphology of the cranial vaults, which are higher than the correlation with the routinely used head circumference (HC). Also, the head height (HH) has a moderate negative correlation (−0.48) with the brain abnormalities of parenchymal volume loss.Interpretation: It is discovered that the head height (HH) is the most sensitive and discriminatory measure of the severity of cranial deformity, which should be used for clinical surveillance of the Zika syndrome, evaluation of other craniofacial syndromes and assessment of various treatment modalities.


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