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2022 ◽  
Vol 14 (2) ◽  
pp. 835
Author(s):  
Hafiz Muhammad Habib ◽  
Hafiz Muhammad Ali ◽  
Muhammad Usman

Condensers are an integral part of air conditioning systems. The thermal efficiency of condensers solely depends on the rate of heat transfer from the cooling medium. Fin tubes are extensively used for heat transfer applications due to their enhanced heat transfer capabilities. Fins provide appreciable drainage because surface tension produces pressure gradients. Much research, contributed by several scientists, has focused on adjusting parameters, such as fin design, flow rates and retention angles. In this study, a setup with an observing hole was used to inspect the influence on retention angle of adjusting the flow rates of the fluid. The increase in retention angle was examined using several velocities and concentration mixtures. Pin-fin tubes were used to obtain coherent results using a photographic method. The experimental setup was designed to monitor the movement of fluid through the apparatus. The velocity was varied using dampers and visibility was enhanced using dyes. Photographs were taken at 20 m/s velocities after every 20 s. and 0.1% concentration and the flooding point observed. The experimental results were verified by standard observation which showed little variation at lower velocity. For water/water-propanol mixtures, a vapor velocity of 12 m/s and concentration ratio of 0.04% was the optimal combination to achieve useful improvement in retention angle. With increase of propanol from 0% to 0.04%, the increase in retention angle was greater compared to 0.04% to 0.1%. For velocities ranging from 0 to 12 m/s, the increase in retention angle was significant. A sharp change was observed for concentration ratios ranging from 0.01% to 0.05% compared to 0.05% to 0.1%.


Author(s):  
Chengxiu Wang ◽  
Mengjie Luo ◽  
Xin Su ◽  
Xingying Lan ◽  
Zeneng Sun ◽  
...  

Particle clusters in CFB risers were identified from the instantaneous solids holdup signals by a new sliding-window based signal processing method. By shifting the sliding time window and calculating the mean and the standard deviation within it, a non-linear threshold curve for identifying the clusters was derived instead of the conventional constant threshold. The optimal sliding window size was determined as Wb = 1024 data points based on the bisection method on the entire piece of signals. Using the proposed method, a more realistic characterization of the clusters in both the HDCFB and LDCFB was obtained by considering the bulk fluctuation of the gas-solids flow. The clusters in the HDCFB have higher solids holdup and lower velocity than that in the LDCFB. The HDCFB is also found to have a greater number of loose clusters for better gas-solids contacting and exchanges in the center of the riser.


2021 ◽  
pp. 117081
Author(s):  
Chunhe Miao ◽  
Songlin Xu ◽  
Yiping Song ◽  
Yushan Xie ◽  
Liangzhu Yuan ◽  
...  

2021 ◽  
Vol 922 (1) ◽  
pp. 66
Author(s):  
Tatiana M. Rodríguez ◽  
Peter Hofner ◽  
Esteban D. Araya ◽  
Qizhou Zhang ◽  
Hendrik Linz ◽  
...  

Abstract We present Very Large Array C-, X-, and Q-band continuum observations, as well as 1.3 mm continuum and CO(2-1) observations with the Submillimeter Array toward the high-mass protostellar candidate ISOSS J23053+5953 SMM2. Compact centimeter continuum emission was detected near the center of the SMM2 core with a spectral index of 0.24(± 0.15) between 6 and 3.6 cm, and a radio luminosity of 1.3(±0.4) mJy kpc2. The 1.3 mm thermal dust emission indicates a mass of the SMM2 core of 45.8 (±13.4) M ⊙, and a density of 7.1 (±1.2)× 106 cm−3. The CO(2-1) observations reveal a large, massive molecular outflow centered on the SMM2 core. This fast outflow (>50 km s−1 from the cloud systemic velocity) is highly collimated, with a broader, lower-velocity component. The large values for outflow mass (45.2 ± 12.6 M ⊙) and momentum rate (6 ± 2 × 10−3 M ⊙ km s−1yr−1) derived from the CO emission are consistent with those of flows driven by high-mass YSOs. The dynamical timescale of the flow is between 1.5 and 7.2 × 104 yr. We also found from the C18O to thermal dust emission ratio that CO is depleted by a factor of about 20, possibly due to freeze-out of CO molecules on dust grains. Our data are consistent with previous findings that ISOSS J23053 + 5953 SMM2 is an emerging high-mass protostar in an early phase of evolution, with an ionized jet and a fast, highly collimated, and massive outflow.


2021 ◽  
Author(s):  
Maria Mytiliniou ◽  
Joeri A.J. Wondergem ◽  
Marleen Feliksik ◽  
Thomas Schmidt ◽  
Doris Heinrich

The G4C2 hexanucleotide repeat expansion in the c9orf72 locus is one among a plethora of mutations associated with amyotrophic lateral sclerosis. It accounts for the majority of disease cases. The exact processes underlying the pathology of this mutation remain elusive, yet recent evidence suggests a mechanism that disrupts axonal trafficking. Here, we used a neuronal cell line with and without the G4C2 repeats, and implemented time-resolved local mean squared displacement analysis to characterize the motion of lysosomes inside neurites. Neurites were either aligned along chemically patterned lines, or oriented randomly on the substrate. We confirmed that in the presence of the G4C2 repeats, lysosome motion was affected. Lysosomes had a smaller reach exhibited lower velocity, especially inside aligned neurites. At the same time they became more active with increasing length of the G4C2 repeats when the neurites were randomly oriented. The duration of diffusive and super-diffusive lysosome transport remained unaffected for both neurite geometries and for all lengths of the repeats, but the displacement and velocity was decreased on varying the repeat number and neurite geometry. Lastly, the ratio of anterograde/retrograde/neutral trajectories was affected disparately for the two neurite geometries. Our observations support the hypothesis that impaired axonal trafficking emerges in the presence of the G4C2 hexanucleotide repeat expansion.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu Lu ◽  
Kaiguo Chen ◽  
Cheng Cheng ◽  
Zhongyu Zhou ◽  
Binqiang Luo ◽  
...  

AbstractThis paper reports on the development of a magnetically driven high-velocity implosion experiment conducted on the CQ-3 facility, a compact pulsed power generator with a load current of 2.1 MA. The current generates a high Lorentz force between inner and outer liners made from 2024 aluminum. Equally positioned photonic Doppler velocimetry probes record the liner velocities. In experiment CQ3-Shot137, the inner liner imploded with a radial converging velocity of 6.57 km/s while the outer liner expanded at a much lower velocity. One-dimensional magneto-hydrodynamics simulation with proper material models provided curves of velocity versus time that agree well with the experimental measurements. Simulation then shows that the inner liner underwent a shock-less compression to approximately 19 GPa and reached an off-Hugoniot high-pressure state. According to the scaling law that the maximum loading pressure is proportional to the square of the load current amplitude, the results demonstrate that such a compact capacitor bank as CQ-3 has the potential to generate pressure as high as 100 GPa within the inner liner in such an implosion experiment. It is emphasized that the technique described in this paper can be easily replicated at low cost.


2021 ◽  
Vol 873 (1) ◽  
pp. 012065
Author(s):  
M S Haq ◽  
Haolia ◽  
M I Sulaiman ◽  
I Madrinovella ◽  
S Satiawan ◽  
...  

Abstract The plate movement, geological structure, magmatism, and seismic activity in the area of Bali to East Nusa Tenggara are mainly related with the subducting of Indo-Australian Plate underneath the Eurasian plate. The complexity is added with the recent collision of Australian continent lithosphere with the western Banda arc, along the islands of Flores, Sumba and Timor island. Our study area is known as the Sunda-Banda arc transition. With the aim of imaging subsurface structure, we perform seismic tomography inversion using regional events. We collected 5 years of earthquake data (January 2015 – December 2019) from the Indonesian Agency of Meteorology, Climatology, and Geophysics (BMKG). The output of our data processing is not limited to only P wave velocity model, but also relocated seismicity pattern in the region. In general, seismicity pattern shows dominant shallow events in the south that progressively shift into deeper events in the north down to a few 500 km, marking a dipping subduction zone in this region. A group of shallow events down to a depth of 50 km is also seen at the norther region that may relate to back-arc thrust activity. P wave tomogram model show a lower velocity perturbation at a depth of 30 km that could be associated with magmatic activity along the volcanic front line. Higher P wave perturbation model are spotted at two different zones, the first one is marking a dipping Indo-Australian plate down to depth of 400 km. We noticed that the angle of dipping is steeper in the Eastern part compared to the Western part. The second a relatively flat at shallow depth at the northern region from the island of Lombok to Nusa Tenggara Timur that may mark the back-arc thrust region


2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Alireza Arabgolarcheh ◽  
Sahar Jannesarahmadi ◽  
Ernesto Benini ◽  
Luca Menegozzo

Over recent years, considerable attention has been devoted to the optimization of energy production in wind farms, where yaw angles can play a significant role. In order to quantify and maximize such potential power, the simulation of wakes is vital. In the present study, an actuator line model code was implemented in the OpenFOAM flow solver. A tip treatment was applied to involve the tip effect induced by the pressure equalization from the suction and pressure sides. The Leishman–Beddoes dynamic stall (LB-DS) model modified by Sheng et al. was employed to consider the dynamic stall phenomenon. The developed ALM-CFD solver was validated for the NREL Phase VI wind turbine reference case. The solver was then used in simulating the yawed wind turbine, and power variation was compared with UBEM and CFD. Overall, according to the obtained data, the coupled solver compared well with CFD. There was an improvement in terms of prediction of the phase delay that is due to the dynamic stall. However, there was still negligible overestimation in deep stall conditions. Based on the obtained results, it is suggested that the reduction of power output follows a cosine to the power of X function of the yaw angle. In terms of visualizing wake, the results demonstrated that the current ALM code was satisfying enough to simulate skewed wake and vortices trajectory. The effect of advancing and retreating blade was captured. It was found that yaw led to the concentration of the induced velocity downstream, resulting in a lower velocity deficit on a broader area, which is essential for wind farm optimization.


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Alexander Vernon Bates ◽  
Alison H. McGregor ◽  
Caroline M. Alexander

Abstract Background Joint Hypermobility Syndrome (JHS) presents with a range of symptoms including widespread joint hypermobility and chronic arthralgia. The study objective was to investigate whether impairments in JHS are due to hypermobility or another factor of JHS by identifying impairments in gait and stair-climbing tasks; an activity that is demanding and so may better show differences between the cohorts. Methods Sixty-eight adults participated; 23 JHS, 23 Generalised Joint Hypermobility (GJH), and 22 Normal Flexibility (NF). Inclusion criteria for JHS participants were a positive classification using the Brighton Criteria, for GJH a Beighton Score ≥ 4, and for NF a Beighton Score < 4 with no hypermobile knees. Participants were recorded with a 10-camera Vicon system whilst they performed gait and stair-climbing. Temporal-spatial, and sagittal plane kinematic and kinetic outcome measures were calculated and input to statistical analyses by statistical parametric mapping (SPM). Results During the gait activity JHS had significantly greater stride time and significantly lower velocity than NF, and significantly greater stride time, lower velocity, and lower stride length than GJH. SPM analysis showed no significant differences between groups in gait kinematics. There were significant differences between groups for gait moments and powers; people with JHS tended to have lower moments and generate less power at the ankle, and favour power generation at the knee. A similar strategy was present in stair ascent. During stair descent people with JHS showed significantly more hip flexion than people with NF. Conclusions As there was only one significant difference between GJH and NF we conclude that impairments cannot be attributed to hypermobility alone, but rather other factor(s) of JHS. The results show that both gait and stair-climbing is impaired in JHS. Stair-climbing results indicate that JHS are using a knee-strategy and avoiding use of the ankle, which may be a factor for clinicians to consider during treatment.


Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3492
Author(s):  
Veronica Mollica ◽  
Stefano Brocchi ◽  
Filippo Gustavo Dall’Olio ◽  
Laura Marcolin ◽  
Alexandro Paccapelo ◽  
...  

Treatment response is usually assessed by the response evaluation criteria in solid tumors (RECIST). These criteria may not be adequate to evaluate the response to immunotherapy, considering the peculiar patterns of response reported with this therapy. With the advent of immunotherapy these criteria have been modified to include the evaluation of the peculiar responses seen with this type of therapy (iRECIST criteria), including pseudoprogressions and hyperprogressions. Tumor growth rate (TGR) is a dynamic evaluation that takes into account the kinetics of response to treatment and may help catch the real efficacy of an immunotherapy approach. We performed a retrospective monocentric study to explore the impact of TGR change after nivolumab administration as the second or later line of treatment in patients with metastatic renal cell carcinoma (RCC). We evaluated 27 patients, divided into three categories: Disease control (DC) if there was no PD; lower velocity PD (LvPD) if disease progressed but the TGR at second assessment (TGR2) was lower than the TGR at first assessment (TGR1); higher velocity PD (HvPD) if TGR2 was higher than TGR1. The median OS for the DC group was 11.0 months (95% CI 5.0–17.0) (reference) vs. (not reached) NR (95% CI NR-NR) for LvPD (HR 0.27; 95% CI 0.06–1.30; p 0.102) vs. NR (95% CI NR–NR) for HvPD (HR 0.23; 95% CI 0.06–0.88; p 0.032). There was no difference between LvPD and DC (HR 1.21; 95% CI 0.20–7.28; p 0.838). In patients with metastatic RCC, the second or later line of nivolumab treatment may lead to a deceleration in TGR resulting in an improved survival outcome similar to that observed in patients experiencing tumor regression. In this subgroup, especially in the presence of a clinical benefit, continuing the treatment beyond progression can be recommended.


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