Production Enhancement in Intermittent Gas Lift Wells Using Sweeping Pipe Bend - Successful Case Histories from Various Onshore Fields in India

Objectives In wells which are producing on intermittent gas lift (IGL), the injected gas cannot sweep the entire liquid volume to the surface from the bottom of the tubing as there is continuously some fluid falling back in the tubing. The fallback can be described as the difference between the volume of the slug at the start of the gas injection and the volume of the actual produced slug at the surface. This fallback of liquid happens due to the fact that the gas has a tendency to flow through the liquid slug and letting the liquid to fall. The intensity of the liquid fallback increases more when there is increase in back pressure at wellhead. In order to minimize this liquid falling back in wells on intermittent gas lift, the sweeping pipe bend technology has been used in the various onshore fields operated by ONGC which has resulted in substantial gains and has been brought out in the paper. Process Gas break through and fallback are affected by three factors including the development of the gas bubble, the velocity of the slug flowing upward in the tubing, and wellhead restrictions caused due to presence of many 90-degree bends. To prevent gas breakthrough and to optimize the liquid fallback to minimum 5-7 % per 1000 feet of lift, it is recommended to maintain 1000 feet/min of minimum velocity of slug. Slower is the velocity of the slug which is moving up in the tubing, the longer time it takes for the gas to break through the liquid. At 1000 feet/min velocity, the wellhead restrictions can result in fallback losses due to breakthrough of gas in the well. In general, the flow path through the Christmas tree into the flowline is rather tortuous, moving first through a tee to the wing valve, then through other 90-degree ells before finally reaching the flowline. These restrictions further result in slowdown of the velocity of the slug thus resulting in more liquid to fallback and subsequently in significant production losses. Results In order to overcome the aforementioned problem and to reduce fallback in an intermittent gas lift well, sweeping pipe bend technology was considered and in the first phase implemented in 5 identified wells of different fields of ONGC Assets. With the help of sweeping pipe bend, the flow pattern becomes streamlined and number of 90-degree bends reduces or eliminates resulting in substantial reduction in the back pressure thus reducing the fall back. The implementation of the technology has resulted in an average liquid gain of 20.3% per well. Various guidelines for successful application of sweeping pipe bend have also been brought out in the paper. Additive Information 650 candidate wells operating on intermittent gas lift have been identified for the implementation of Sweeping Pipe Bends. As per the analysis, the implementation of Sweeping Pipe Bend is likely to result in a liquid gain of about 1000 m3/day from these wells.

Portal venous and hepatic artery hemodynamic variation in non-alcoholic fatty liver disease

Background Non-alcoholic fatty liver disease remains asymptomatic until advanced disease, when risk factor modification and available treatment become no longer effective. Studies on hepatic vasculature can be informative about parenchymal injury and disease severity through the study of changes affecting vascular compliance. This study aimed to study portal vein and hepatic artery hemodynamic variation in non-alcoholic fatty liver and to correlate it with disease severity. Results This case control study included 80 participants; those were further divided into four groups; healthy volunteers and non-alcoholic fatty liver disease patients’ grade 1, 2, and 3. We did anthropometric measures, laboratory tests, transient elastography, and Doppler ultrasound for all participants, and then we collected the data and analyzed it using SPSS version 25. Doppler findings showed that peak maximum velocity, peak minimum velocity, mean flow velocity, portal vein pulsatility index of portal vein, and hepatic artery resistivity index were significantly lower in non-alcoholic fatty liver disease patients than in healthy people. All indices were indirectly proportionate to the grade of the disease except for peak minimum velocity which was significantly lower on comparing grade 3 patients with grades 1 and 2 patients. Conclusions Reduction of portal flow and increase in hepatic artery flow in fatty liver correlates with disease severity and can help as a non-invasive measure in diagnosis and grading of non-alcoholic fatty liver disease.

Can a Semi-Active Energy Harvesting Shock Absorber Mimic a Given Vehicle Passive Suspension?

Energy harvesting shock absorbers (EHSA) have made great progress in recent years, although there are still no commercial solutions for this technology. This paper addresses the question of whether, and under what conditions, an EHSA can completely replace a conventional one. In this way, any conventional suspension could be replicated at will, while recovering part of the wasted energy. This paper focuses on mimicking the original passive damper behavior by continuously varying the electrical parameters of the regenerative damper. For this study, a typical ball-screw EHSA is chosen, and its equivalent suspension parameters are tried to be matched to the initial damper. The methodology proposes several electrical control circuits that optimize the dynamic behavior of the regenerative damper from the continuous variation of a load resistance. The results show that, given a target damper curve, the regenerative damper can adequately replicate it when there is a minimum velocity in the damper. However, when the damper velocity is close to zero, the only way to compensate for inertia is through the introduction of external energy to the system.

Prediction of One Repetition Maximum Using Reference Minimum Velocity Threshold Values in Young and Middle-Aged Resistance-Trained Males

Background: This study determined the accuracy of different velocity-based methods when predicting one-repetition maximum (1RM) in young and middle-aged resistance-trained males. Methods: Two days after maximal strength testing, 20 young (age 21.0 ± 1.6 years) and 20 middle-aged (age 42.6 ± 6.7 years) resistance-trained males completed three repetitions of bench press, back squat, and bent-over-row at loads corresponding to 20–80% 1RM. Using reference minimum velocity threshold (MVT) values, the 1RM was estimated from the load-velocity relationships through multiple (20, 30, 40, 50, 60, 70, and 80% 1RM), two-point (20 and 80% 1RM), high-load (60 and 80% 1RM) and low-load (20 and 40% 1RM) methods for each group. Results: Despite most prediction methods demonstrating acceptable correlations (r = 0.55 to 0.96), the absolute errors for young and middle-aged groups were generally moderate to high for bench press (absolute errors = 8.2 to 14.2% and 8.6 to 20.4%, respectively) and bent-over-row (absolute error = 14.9 to 19.9% and 8.6 to 18.2%, respectively). For squats, the absolute errors were lower in the young group (5.7 to 13.4%) than the middle-aged group (13.2 to 17.0%) but still unacceptable. Conclusion: These findings suggest that reference MVTs cannot accurately predict the 1RM in these populations. Therefore, practitioners need to directly assess 1RM.

Use of Machine-Learning and Load–Velocity Profiling to Estimate 1-Repetition Maximums for Two Variations of the Bench-Press Exercise

The purpose of the current study was to compare the ability of five different methods to estimate eccentric–concentric and concentric-only bench-press 1RM from load–velocity profile data. Smith machine bench-press tests were performed in an eccentric–concentric (n = 192) and a concentric-only manner (n = 176) while mean concentric velocity was registered using a linear position transducer. Load–velocity profiles were derived from incremental submaximal load (40–80% 1RM) tests. Five different methods were used to calculate 1RM using the slope, intercept, and velocity at 1RM (minimum velocity threshold—MVT) from the load–velocity profiles: calculation with individual MVT, calculation with group average MVT, multilinear regression without MVT, regularized regression without MVT, and an artificial neural network without MVT. Mean average errors for all methods ranged from 2.7 to 3.3 kg. Calculations with individual or group MVT resulted in significant overprediction of eccentric–concentric 1RM (individual MVT: difference = 0.76 kg, p = 0.020, d = 0.17; group MVT: difference = 0.72 kg, p = 0.023, d = 0.17). The multilinear and regularized regression both resulted in the lowest errors and highest correlations. The results demonstrated that bench-press 1RM can be accurately estimated from load–velocity data derived from submaximal loads and without MVT. In addition, results showed that multilinear regression can be used to estimate bench-press 1RM. Collectively, the findings and resulting equations should be helpful for strength and conditioning coaches as they would help estimating 1RM without MVT data.

Assessment of multitemporal INSAR data for establishing regional landslides inventories

<p>Over 2700 gravitational movements are recorded as polygons in the inventory of the Aosta region (3261 km2, Northern Italy). The surface affected by gravitational processes is about 20% of the overall surface area of the Aosta region and corresponds mostly to deep seated slope deformations, landslides and rock slope collapses. In addition, a complete set of multitemporal INSAR data has been recently made available for the same area (SqueeSAR processing by TRE, for both ascending and descending orbits, from October 2014 to February 2020).</p><p>In a first step, the distribution of INSAR data was analyzed with respect to landcover and radar geometric deformations. Main outcomes are:</p><ul><li>About 732’000 points were found by INSAR corresponding to a total average density of ~220 pts/km2.</li> <li>0% of points have velocities below 1 mm/y, 20.4% between 1 and 10 mm/y, and only 0.6% more than 1 cm/y.</li> <li>The landcover is forested over 30% of the surface, covered by low vegetation on steep slopes for 46% and unvegetated for 24%, Points density are respectively 146, 200 and 369 pts /km2.</li> <li>Less than 5% of the Aosta region is affected by radar layover or shadowing. But, considering the slope direction as possible vector of displacement, 60% of INSAR velocities are underestimated of 50% or more when projected on the line of sight of the satellite (of course most of the time these are not the same slopes for ascending and descending orbits).</li> </ul><p>In a second step, we assessed the information provided by INSAR for the landslides recorded in the IFFI inventory:</p><ul><li>29% of the polygons of the IFFI inventory do not include INSAR pts. However, those are mostly small zones, corresponding to only 9% of the total surface mapped as affected by gravitational movements. Most of large instabilities have INSAR points. 52% of the polygons have INSAR points from both ascending and descending orbits, and 19% from only one orbit.</li> <li>68% of IFFI polygons have all their INSAR velocities slower than 5mm/y (for both orbits). It doesn’t mean automatically that these instabilities are dormant or slow moving, because for about half of them INSAR velocities strongly underestimate expected real velocities because of unfavorable projection on the line of sight of the satellites.</li> <li>55 instabilities show INSAR velocities between 50 and 10 mm/y, and 31 faster than 10 mm/y.</li> </ul><p>Finally, an independent inventory was made using only the INSAR data and then compared to the IFFI inventory. In order to handle the data, a minimum velocity 2.5 mm/y was selected.</p><ul><li>1437 instabilities were mapped in this inventory, covering 308 km2, for 2702 instabilities over 604 km2 in the IFFI inventory.</li> <li>About 60% of the moving area detected looking only at the INSAR data are visible on only one orbit (ascending or descending).</li> <li>62 clusters of INSAR points with velocities higher than 1 cm/y and not in the IFFI polygons were detected. Among them, 4 sites with significant extensions will require further geological investigations.</li> </ul>

Relationships between biomechanical parameters, neurological recovery, and neuropathology following concussion in swine

ABSTRACTMild traumatic brain injury (mTBI) affects millions of individuals annually primarily through falls, traffic collisions, or blunt trauma and can generate symptoms that persist for years. Closed-head rotational injury is the most common form of mTBI and is defined by a rapid change in acceleration within an intact skull. Injury kinematics – the mechanical descriptors of injury-inducing motion – explain movement of the head, energy transfer to the brain, and, therefore, determine injury severity. However, the relationship between closed-head rotational injury kinematics – such as angular velocity, angular acceleration, and injury duration – and outcome after mTBI is currently unknown. To address this gap in knowledge, we analyzed archived surgical records of 24 swine experiencing a diffuse closed-head rotational acceleration mTBI against 12 sham animals. Kinematics were contrasted against acute recovery outcomes, specifically apnea, extubation time, standing time, and recovery duration. Compared to controls, animals with mTBI were far more likely to have apnea (p<0.001) along with shorter time to extubation (p=0.023), and longer time from extubation to recovery (p=0.006). Using regression analyses with variable selection, we generated simplified linear models relating kinematics to apnea (R2=0.27), standing time (R2=0.39) and recovery duration (R2=0.42). Neuropathology was correlated with multiple kinematics, with maximum acceleration exhibiting the strongest correlation (R2=0.66). Together, these data suggest the interplay between multiple injury kinematics, including minimum velocity and middle to minimum acceleration time, best explain acute recovery parameters and neuropathology after mTBI in swine. Future experiments that independently manipulate individual kinematics could be instrumental in developing translational diagnostics for clinical mTBI.HIGHLIGHTSAcute recovery parameters including apnea, extubation time, and recovery duration were altered after a single closed-head mTBI in swine.Lasso-based regressions utilized kinematic parameters, including minimum velocity and middle to minimum acceleration time, to relate kinematics to apnea time, standing time, and recovery duration.Lasso regression equations were able to modestly predict apnea time (R2=0.27) and moderately predict standing time (R2=0.39) and recovery duration (R2=0.42).Injury kinematic parameters, primarily maximum acceleration, were correlated with white matter pathology after mTBI.

ERRATA to “Secondary Flows, Endwall Effects, and Stall Detection in Axial Compressor Design.” ASME. J. Turbomach. May 2015; 137(5): 051004, DOI: 10.1115/1.4028648

In the published paper, the expressions listed under (51) were miswritten. And the following sentence should be: “Hub and tip minimum velocity ratios are divided by a factor of 1.3 due to the ability of the blade row to operate stably in spite of the presence of corner stall.”

Deposits from giant floods in Gale crater and their implications for the climate of early Mars

This study reports in-situ sedimentologic evidence of giant floods in Gale crater, Mars, during the Noachian Period. Features indicative of floods are a series of symmetrical, 10 m-high gravel ridges that occur in the Hummocky Plains Unit (HPU). Their regular spacing, internal sedimentary structures, and bedload transport of fragments as large as 20 cm suggest that these ridges are antidunes: a type of sedimentary structure that forms under very strong flows. Their 150 m wavelength indicates that the north-flowing water that deposited them was at least 24 m deep and had a minimum velocity of 10 m/s. Floods waned rapidly, eroding antidune crests, and re-deposited removed sediments as patches on the up-flow limbs and trough areas between these ridges forming the Striated Unit (SU). Each patch of the SU is 50–200 m wide and long and consists of 5–10 m of south-dipping layers. The strike and dip of the SU layers mimic the attitude of the flank of the antidune on which they were deposited. The most likely mechanism that generated flood waters of this magnitude on a planet whose present-day average temperature is − 60 °C was the sudden heat produced by a large impact. The event vaporized frozen reservoirs of water and injected large amounts of CO2 and CH4 from their solid phases into the atmosphere. It temporarily interrupted a cold and dry climate and generated a warm and wet period. Torrential rainfall occurred planetwide some of which entered Gale crater and combined with water roaring down from Mt. Sharp to cause gigantic flash floods that deposited the SU and the HPU on Aeolis Palus. The warm and wet climate persisted even after the flooding ended, but its duration cannot be determined by our study.

Group versus Individualised Minimum Velocity Thresholds in the Prediction of Maximal Strength in Trained Female Athletes

This study examined the accuracy of different velocity-based methods in the prediction of bench press and squat one-repetition maximum (1RM) in female athletes. Seventeen trained females (age 17.8 ± 1.3 years) performed an incremental loading test to 1RM on bench press and squat with the mean velocity being recorded. The 1RM was estimated from the load–velocity relationship using the multiple- (8 loads) and two-point (2 loads) methods and group and individual minimum velocity thresholds (MVT). No significant effect of method, MVT or interaction was observed for the two exercises (p > 0.05). For bench press and squat, all prediction methods demonstrated very large to nearly perfect correlations with respect to the actual 1RM (r range = 0.76 to 0.97). The absolute error (range = 2.1 to 3.8 kg) for bench press demonstrated low errors that were independent of the method and MVT used. For squat, the favorable group MVT errors for the multiple- and two-point methods (absolute error = 7.8 and 9.7 kg, respectively) were greater than the individual MVT errors (absolute error = 4.9 and 6.3 kg, respectively). The 1RM can be accurately predicted from the load–velocity relationship in trained females, with the two-point method offering a quick and less fatiguing alternative to the multiple-point method.