Increasing the Flow Capacity of Hoses with Electrical-Heater Coils to Supply Thickened Preservatives for Spraying

Introduction. Anticorrosion protection of agricultural machinery working elements is provided through using pneumatic application of thickened preservatives with heating. For this purpose, a wire coil is inserted inside the preservative-supply hose and connected to a current source. It is known that the wire thickness and the coil pitch affect the hydraulic resistance to fluid flow. However, it has not been established how the diameter of the coil insert and its heating affect the flow capacity of the flexible hose channel. The purpose of the research is to increase the capacity of a flexible hose with an electrical-heater coil. For this purpose, it is necessary to determine its geometric parameters minimizing the hydraulic resistance to the thickened preservative flow and reducing the energy consumption for heating the material in the hose. Materials and Methods. It is proposed to investigate two electrical-heater coils of the same length, but of different diameter, made of steel welding wire pieces of equal length. There was developed a stand to study the influence of the inserted coil parameters on the hose hydraulic resistance. The stand was used to determine pressure losses in hoses with coils and in smooth hoses when used engine oil and thickened preservative flow through them. The flow capacity of the hose with cold and heated coils was estimated. Results. The method of heating the preservative in the hose wall layer is justified. At the same time, its flow capacity increases one and a half times with less energy consumption (2.4 times) than when heating the preservative in the central part of the hose. Under laminar flow mode, the pressure loss in the hose is 2 times lower when the coil is equal to 0.85 of the hose channel diameter than when the coil is equal to 0.67 of the channel diameter. Discussion and Conclusion. The research found the rational way of placing the electrical coil near the heated hose channel wall. At low air temperature, the reduction of the thickened preservative viscosity by heating in the hose helps to decrease the pressure loss up to 50% and increase its flow capacity by 1.4‒2.0 times. The use of a electrical-heater coil in the hose with thickened preservative will minimize energy consumption when preserving equipment on open storage sites.

Network Robustness Analysis Based on Maximum Flow

Network robustness is the ability of a network to maintain a certain level of structural integrity and its original functions after being attacked, and it is the key to whether the damaged network can continue to operate normally. We define two types of robustness evaluation indicators based on network maximum flow: flow capacity robustness, which assesses the ability of the network to resist attack, and flow recovery robustness, which assesses the ability to rebuild the network after an attack on the network. To verify the effectiveness of the robustness indicators proposed in this study, we simulate four typical networks and analyze their robustness, and the results show that a high-density random network is stronger than a low-density network in terms of connectivity and resilience; the growth rate parameter of scale-free network does not have a significant impact on robustness changes in most cases; the greater the average degree of a regular network, the greater the robustness; the robustness of small-world network increases with the increase in the average degree. In addition, there is a critical damage rate (when the node damage rate is less than this critical value, the damaged nodes and edges can almost be completely recovered) when examining flow recovery robustness, and the critical damage rate is around 20%. Flow capacity robustness and flow recovery robustness enrich the network structure indicator system and more comprehensively describe the structural stability of real networks.

Effect of hub clearance size and shape of a cantilevered stator on the performance of a small-scale transonic axial compressor

To deeply understand the hub leakage flow and its influence on the aerodynamic performance and flow behaviors of a small-scale transonic axial compressor, variations of the performance and the flow field of the compressor with different hub clearance sizes and clearance shapes were numerically analyzed. The results indicate that the hub clearance size has remarkable impacts on the overall performance of the compressor. With the increase of the hub clearance, the intensity of the hub leakage flow increases, resulting in more intense flow blockage near the stator hub, which reduces the compressor efficiency. However, the flow field near the blade mid-span is modified due to the more convergent flow as the reduced effective flow area caused by the passage blockage, and the flow separation range is narrowed, thus the flow stability of the compressor is enhanced. On this basis, two kinds of non-uniform clearance cases of expanding clearance and shrinking clearance with the same circumferential leakage area as the design clearance were investigated. The occurrence position of the double leakage flow which is closely connected with the flow loss and blockage is shifted backward by the expanding clearance, the flow capacity near the stator hub is enhanced, and the unsteady fluctuation intensity of the flow field is attenuated but fluctuation frequency remains. Similarly, the modification of the stator blade root flow field may result in the reduction of stall margin. The effect of the shrinking clearance on compressor performance is opposite to that of the expanding clearance, which reduces the peak efficiency and delays the stall inception.

Comparison of the Prognostic Value of Global and Regional Myocardial Flow Capacity Radius, Myocardial Flow Reserve, and Stress Myocardial Blood Flow Using Rubidium-82 with SiPM PET/CT

Purpose The aim of this study was to assess the most reliable quantitative variable on Rubidium-82 (82Rb) cardiac PET/CT for predicting major adverse cardiovascular events (MACE), on the latest PET camera using silicon photomultipliers digital readout (SiPM) technology. Methods We prospectively enrolled 274 consecutive participants with suspected myocardial ischemia. Participants underwent 82Rb cardiac SiPM PET/CT and were followed-up for MACE over 652 days (interquartile range: 559 to 751 days). For each participant, global and regional myocardial flow reserve (MFR), stress myocardial blood flow (stress MBF) and their combination as myocardial flow capacity radius (MFC radius) were measured. Results On receiver operator curve analysis, MACE prediction was similar for global and regional MFR, stress MBF, and MFC radius (area under the curve; (i) Global: 0.70 vs. 0.71 and 0.73, and (ii) Regional: 0.71 vs. 0.71 and 0.73, respectively, p > 0.1 for all pairwise comparisons). On multivariable analysis, (i) Global: MFR < 1.98, stress MBF < 1.94 mL/g/min, and MFC radius < 3.12, as well as (ii) Regional: MFR < 1.75, stress MBF < 1.75 mL/g/min, and MFC radius < 2.7, emerged all as similar independent predictors of MACE (p < 0.001 for all). Conclusions Using the latest SiPM PET technology with 82Rb, global and regional MFR, stress MBF, and MFC radius are similar powerful predictors of cardiovascular event.

The FACT : Use of a novel intermittent pneumatic compression device to promote pre-surgery arm vein dilation in patients with chronic renal failure

Background: Arteriovenous fistula (AVF) creation and maturation for hemodialysis is globally a topic of importance given the poor results and high costs associated with renal care. Successful AVF (surgical or endovascular) creation requires appropriate superficial veins and quality arteries. Many procedures fail due to initial small veins with limited blood flow capacity and distensibility. Intermittent pneumatic compression has previously shown success in trials to increase superficial veins in patients with end stage renal disease post AVF. The objective of this study is to investigate the role of an intermittent pneumatic device, the Fist Assist®, to dilate cephalic arm veins in patients with advanced chronic kidney disease (CKD) prior to AVF placement. Methods: Three centers enrolled subjects from June 2019 through July 2021. Baseline Doppler measurements of the cephalic vein in standard locations the forearm and upper arm with and without a blood pressure cuff were recorded. Patients were instructed and used Fist Assist® on their non-dominant arm for up to 4 h daily for 90 days. At approximately 3 months, Doppler measurements were repeated. The primary endpoint was cephalic vein enlargement with secondary endpoints based on percentage of veins approaching 2.5 mm in the forearm and 3.5 mm in the upper arm. Results: Thirty-seven subjects with CKD (mean eGFR 13.8 mL/min) were enrolled and completed the trial. Paired-difference t-tests (one tail) for aggregate data showed significant venous dilation of the cephalic vein in both the forearm and upper arm after use with the Fist Assist® ( p < 0.05). Mean differences in the forearm veins were approximately 0.6 and 1.1 mm in the upper arm cephalic vein after Fist Assist® application. There were no major complications reported by any subject during the trial. Conclusions: Fist Assist® use in patients with CKD is effective to enhance vein dilation. Forearm and upper arm cephalic veins increased on average 0.6 and 1.1 mm respectively after Fist Assist® application. This is the first trial to evaluate the effect of intermittent, focal pneumatic compression on pre-surgery vein diameter in patients with advanced CKD before AVF creation.

Design and Control of an Inflatable Spherical Robotic Arm for Pick and Place Applications

We present an inflatable soft robotic arm made of fabric that leverages state-of-the-art manufacturing techniques, leading to a robust and reliable manipulator. Three bellow-type actuators are used to control two rotational degrees of freedom, as well as the joint stiffness that is coupled to a longitudinal elongation of the movable link used to grasp objects. The design is motivated by a safety analysis based on first principles. It shows that the interaction forces during an unexpected collision are primarily caused by the attached payload mass, but can be reduced by a lightweight design of the robot arm. A control allocation strategy is employed that simplifies the modeling and control of the robot arm and we show that a particular property of the allocation strategy ensures equal usage of the actuators and valves. The modeling and control approach systematically incorporates the effect of changing joint stiffness and the presence of a payload mass. An investigation of the valve flow capacity reveals that a proper timescale separation between the pressure and arm dynamics is only given for sufficient flow capacity. Otherwise, the applied cascaded control approach can introduce oscillatory behavior, degrading the overall control performance. A closed form feed forward strategy is derived that compensates errors induced by the longitudinal elongation of the movable link and allows the realization of different object manipulation applications. In one of the applications, the robot arm hands an object over to a human, emphasizing the safety aspect of the soft robotic system. Thereby, the intrinsic compliance of the robot arm is leveraged to detect the time when the robot should release the object.

A 2D model for the study of equilibrium glide paths of UiS Subsea Freight-Glider

A planar mathematical model for the analysis of equilibrium glide paths of the UiS subsea freight-glider (USFG) is presented. The model is developed using Simscape Multibody in MATLAB/Simulink to study the ever-changing dynamics of the glider. Motion along the heave and pitch direction is regulated by two separate PID controllers. Controllers are tuned for the optimal bandwidth and phase margin to provide the system with ideal gains which satisfy the system requirements. A wide-ranging sensitivity investigation is carried out on the USFG by changing the two key variables, pump flow rate and ballast fraction. The results reflect the advantages of using higher flow capacity and ballast fraction, which should be preferred according to the application, provided if there are no space and weight restrictions. Finally, different glide paths were simulated to observe that, controller gains obtained from the linear model can be improved to acquire better performance in terms of robustness and stability of the system.

Sometimes the Hard Part Is Not Solving the Problem; It Is Finding a Way To Deliver the Solution

LiquidPower Specialty Products Inc. (LSPI) said it can increase the flow capacity of subsea flowlines from wells to platforms by up to 35%. Based on the company’s long history in that business, that sounds doable. The hard part is convincing users that it can dependably deliver the chemical to the offshore wells where it is needed. The delivery barrier has made subsea production lines one of the few oil pipeline markets not served by LSPI, whose history dates to 1979 when it began selling an additive, a drag-reducing agent (DRA), that dramatically increased pipeline flows. The polymer was invented by scientists at what was then Conoco, in the early 1970s. Among the inventors was Yung Lee, who is still with the company which is now owned by Berkshire Hathaway. The chemical able to increase oil flows by 80% proved popular, and its use spread around the world. Now, the maker of a product used in 80% of US oil pipelines is looking for new markets. Lines running from offshore wells to platforms look like an attractive growth market, as oil companies focus on finding oil near existing platforms where the risks and costs are low. “It is going to be substantial. It is not huge like pipelines. Still, more and more people are going to discover oil-bearing formations away from platforms,” said Lee, engineering and technical services director for LSPI. The short explanation for how LSPI’s DRA works is that the long molecular chains of the ultrahigh-weight polymer in a pipeline reduce turbulence. That allows more oil to flow through a pipe and reduces the pressure needed to do so. There are offshore markets for DRA, where it is used in large lines delivering oil to shore and in multiphase lines connecting platforms. Pipelines from subsea wells to platforms are not on the list because LSPI has been unable to find a way to deliver DRA to those remote locations. The obvious way to do so would seem to be to pump the relatively small amount of chemical needed each day through an umbilical. For more than 15 years, LSPI tried to develop a DRA molecule that would flow dependably through the narrow tube in an umbilical. The problem was “DRAs contain solid particles [polymer] that will coat the internal wall and eventually plug the umbilical,” according to a recent Offshore Technology Conference (OTC) paper describing the prolonged search (OTC 31054). That problem created an opportunity for Safe Marine Transfer, which was looking for customers needing an alternative delivery method, said Art Schroeder, CEO of the Houston company. Inside the Box Three years ago, at the OTC, LSPI met the founders of Safe Marine, who convinced them to consider delivering DRA in a box. The box intentionally looks like a cargo container. Its dimensions— 40×8×8.5 ft—make it possible to load the box on a truck and move it to a dock on its way offshore. Inside is a large, tough bladder designed to hold 200 bbl of fluid. The container allows water to enter, equalizing the pressure so the frame can stand up to extreme deepwater pressure.