Set Of Valves Research Articles

Embedded gas sensing setup for air samples analysis.

This paper describes a measurement setup (eNose) designed to analyze air samples containing various volatile organic compounds (VOCs). The setup utilizes a set of resistive gas sensors of divergent gas selectivity and sensitivity. Some of the applied sensors are commercially available and were proposed recently to reduce their consumed energy. The sensors detect various VOCs at sensitivities determined by metal oxide sensors' technology and operating conditions. The setup can utilize prototype gas sensors, made of resistive layers of different compositions, as well. Their properties can be modulated by selecting operating temperature or using UV light irradiation. The unit is controlled by an embedded system M5Stack Core2 ESP32 IoT. We used this development kit to program the measurement procedure and data recording fastly. The setup utilizes an aluminum gas chamber of a volume of 220 ml, a set of electrical valves to introduce there an air sample with the help of an electrical micropump. The handling of the setup was simplified to a selection of a few operations by touch screen only without a necessity of extra training. The recorded data are saved in a memory card for further processing. The evolved setup can be upgraded to apply more advanced data processing by utilizing WiFi or Bluetooth connection. The control program was prepared using the Arduino IDE software environment and can be further advanced with ease. The applied materials and the established measurement procedure can use various air samples, including exhaled breath samples for patients' screening check-ups. We applied the same time of 10min for response and recovery, acceptable for practical use.

Optimal Service Points (OSP) for PHM Enabled Condition Based Maintenance for Oil and Gas Applications

In recent times, the oil and Gas industry has faced many challenges resulting from a tightening climate policy environment on oil and gas exploration, as well as the increasing risk of oversupply due to new discoveries globally. This has given stakeholders in the industry an incentive to integrate new technologies to optimize the operational efficiency of their assets, leading to the optimal recovery of hydrocarbons especially in marginal fields. Various Original Equipment Manufacturers (OEM) now provide different service offerings using data driven methods to provide condition monitoring of assets for oil and gas operators. However, a significant part of the value proposition by OEMs in their service delivery focuses on value generated at the component level with a reduction in asset downtime. This limits the broad economic benefits that a condition-based approach can provide, at the enterprise level. Therefore, the purpose of this paper is to develop a cost benefit analysis framework for assessing the implementation of condition and performance monitoring of oil and gas assets used in surface applications. The framework utilizes a combined technical-economic approach to determine a minimum predictive requirement for the implementation of condition-based principles to maintenance of assets in a hydrocarbon project from first oil to abandonment. This financial analysis framework uses a condition monitoring approach based on prognostics as well as a regression approach for fault detection and system performance. The paper will present a case study to evaluate the costs and benefits associated with implementing a condition-based maintenance approach for a set of valves in a Christmas tree subsystem, as part of a typical onshore production system. The framework illustrated using the case study compares a constant failure rate Time-Based approach to the PHM enabled condition-based maintenance. The results demonstrate that a prognostic enabled system can provide commercial benefits at the component level for a Condition Based Maintenance strategy but not necessarily at the enterprise level for an oil and gas project. The cumulative reduction in downtime at the component level over a project lifecycle offsetting the present value of the total cost of integrating a PHM enabled system into the overall maintenance strategy creates the ideal situation for commercial viability. However, the commercial viability of the PHM integration would depend on the accuracy of predicting failure events and monitoring asset degradation by the PHM enabled system which ultimately defines the performance of the condition-based maintenance approach. The accuracy level of asset failure therefore provides OEMs with a benchmark for executing their condition-based maintenance services with a minimum performance threshold. Secondly, an enterprise level financial viability, as well as OEM profitability in the implementation of a condition-based maintenance approach, requires an Optimal Service Point (OSP) which is a function of the minimum predictive requirement of the PHM system. The utility that the OSP provides is that, it gives the minimum value of the framework’s decision criteria that an operator can use a basis for incorporating a condition-based approach in its maintenance strategy. It also provides the maximum Annual Service Fee (ASF) derived from the cumulative OEM NPV needed for structuring and pricing servitization agreements with operators. This OSP cost benefit analysis approach ultimately provides OEMs and operators with a practical guide in the provision as well as the adoption of condition-based maintenance strategies respectively. It balances the risk of PHM integration by operators with a minimum PHM system performance threshold required for commercial viability for project lifecycle.

Changes in electromyographic activity, mechanical power, and relaxation rates following inspiratory ribcage muscle fatigue

Muscle fatigue is a complex phenomenon enclosing various mechanisms. Despite technological advances, these mechanisms are still not fully understood in vivo. Here, simultaneous measurements of pressure, volume, and ribcage inspiratory muscle activity were performed non-invasively during fatigue (inspiratory threshold valve set at 70% of maximal inspiratory pressure) and recovery to verify if inspiratory ribcage muscle fatigue (1) leads to slowing of contraction and relaxation properties of ribcage muscles and (2) alters median frequency and high-to-low frequency ratio (H/L). During the fatigue protocol, sternocleidomastoid showed the fastest decrease in median frequency and slowest decrease in H/L. Fatigue was also characterized by a reduction in the relative power of the high-frequency and increase of the low-frequency. During recovery, changes in mechanical power were due to changes in shortening velocity with long-lasting reduction in pressure generation, and slowing of relaxation [i.e., tau (τ), half-relaxation time (½RT), and maximum relaxation rate (MRR)] was observed with no significant changes in contractile properties. Recovery of median frequency was faster than H/L, and relaxation rates correlated with shortening velocity and mechanical power of inspiratory ribcage muscles; however, with different time courses. Time constant of the inspiratory ribcage muscles during fatigue and recovery is not uniform (i.e., different inspiratory muscles may have different underlying mechanisms of fatigue), and MRR, ½RT, and τ are not only useful predictors of inspiratory ribcage muscle recovery but may also share common underlying mechanisms with shortening velocity.

Physical Performance Testing of a Prototype Gerotor Pump Operating in Liquid and Gas/Liquid Conditions

Summary Gerotors are positive displacement pumps and potential artificial lift options in the oil and gas industry. This study presents the performance characteristics from physical testing of a unique one-stage, equal-walled gerotor pump design operating in oil and oil/air mixtures. The pump was tested at various rotational speeds in a flow loop. The performance results were obtained to ascertain potential design optimizations of the pump before embarking on manufacturing and testing of the field prototype pump. A physical prototype of a one-stage 400 series gerotor pump, suitable for application in a 5.5-in. casing, was designed, manufactured, assembled, and tested. Mineral oil and air were used as the operating media. For given pump outlet valve settings, the pump rotational speeds were set to 200, 250, 300, and 350 rev/min. Gas volume fractions (GVFs) at the pump inlet were varied from 0% to the maximum the current pump design could handle. For each test point, the corresponding pump parameters were measured. Dimensionless performance plots were established for obtaining pump performance at other flow conditions. The results showed that pump flow rate decreased with increasing differential pressure, typical of positive displacement pumps. At 200 and 350 rev/min, maximum pump delivery is approximately 190 and 330 B/D of oil, respectively, at zero differential pressure. The pump can supply flow against a differential pressure of up to approximately 5.5 psi at 200 rev/min and 15 psi at 350 rev/min. For the 200 to 350 rev/min speed range, volumetric efficiencies varied from 30 to 73%, whereas the electric power input varied from 145 to 191 W. When pumping oil/air mixtures, the current gerotor pump design can handle 15% GVF maximum, at 250, 300, and 350 rev/min. For certain pump outlet pressures, the total fluid flow rates decreased as the GVF increased to 15%. The volumetric efficiencies at 15% GVF varied from 32 to 53% for the 300 to 350 rev/min speed range, whereas the motor electric power input decreased with increasing GVF up to 15%. In conclusion, increasing the pump rotational speed improves the volumetric efficiency and gas-handling capability of the gerotor pump. These observations will aid in the required design optimization to enhance the performance of the future field prototype gerotor pump. This study presents the capabilities of gerotors as potential artificial lift alternatives to handle liquid and gas/liquid mixtures for boosting applications in oilfield operations. The technology with additional design optimization can be readily integrated into oilfield equipment architecture. The mechanical simplicity of gerotors and their compactness provides a promising artificial lift substitute that may be implemented for downhole or surface production of liquid or gas/liquid mixtures in the oil and gas industry.

Metallurgical failure analysis of non-separation of isolation pyro valve used in space applications

Isolation pyro valves fabricated from AISI 321 austenitic stainless steel are performance-critical components used in launch vehicle propulsion systems. These valves isolate the fuel and oxidizer separated by a thin membrane that will be severed during its operation. As a part of the qualification program, a set of pyro valves were tested at the operating temperature of 20 K. During post-test examination of the hardware, membrane separation was not observed in one of the pyro valves tested. The failed and successfully tested valves were analysed to understand the reason for the non-separation of the pyro valve membrane. The present work brings out the details of metallurgical and mechanical aspects of the failed as well as successfully tested isolation pyro valves.

A recurring case of ‘no trace, right place’ during emergency tracheal intubations in the critical care setting

We wish to highlight a safety issue concerning the use of the Mapleson C circuit along with high fresh gas flows and the potential impact this could have on capnography. The authors have encountered a situation where despite successful tracheal intubation, there can be continued failure to detect carbon dioxide. This issue became apparent during the undertaking of a large number of emergency tracheal intubations in the current COVID-19 pandemic. The cases involved patients with uneventful airway management and clear placement of a tracheal tube between the vocal cords using videolaryngoscopy. This was followed in all cases by the clinical confirmation of successful tracheal intubation but the absence of a capnographic trace. A commonly identified feature in all events was very high fresh gas flow to the Mapleson C circuit. This high flow was unintentional and frequently had been commenced by a clinician assisting with the tracheal intubation, before the arrival of the intubator. Furthermore, the high flow was initially unrecognised due to the urgent nature of the situation and the impact of personal protective equipment. The standard oxygen flowmeter present in most wards or resuscitation bays displays flow graduations of up to 15 l.min-1. The authors found that while often the last graduation marked is 15 l.min-1, these devices are not flow-limited and when the valve is opened fully can generate flows much higher than this. Further investigation of the technical data supplied by the manufactures of several flowmeters reveals that the high flows produced when the valve is opened fully are referred to as ‘flush’ or ‘flood’ flows and can be as high as 90 l.min-1 [1]. The authors confirmed this by testing the flows generated from oxygen flowmeters encountered throughout their hospital including the auxiliary oxygen outlet present on the anaesthetic machine which produced 84 l.min-1 oxygen while a standard ward oxygen flowmeter achieved 75 l.min-1. When the situation was encountered again and the high flows identified, a capnographic trace could be produced by turning down the oxygen flow to the Mapleson C circuit. The exact cause of this phenomenon is yet to be determined but correspondence with the manufacturer of the Mapleson C circuit suggests that carbon dioxide washout is the likely cause. However, a number of confounders may also contribute and they include the flowmeters flush rate, the composition of the circuit, the type of heat and moisture exchange filter, the behaviour of the adjustable pressure limiting (APL) valve, the adequacy of the tracheal tube cuff and the patient's pulmonary compliance. A review of the technical data provided by the manufacturers of the Mapleson C circuit, revealed that with the APL valve set in the semi-closed position, a fresh gas flow of 50 l.min-1 will generate a resistance of 32 cmH2O (Technical document, Armstrong Medical, Coleraine). The authors will explore these concepts further in a laboratory setting. The current pandemic has seen oxygen capacity in hospitals come under strain due to the large number of COVID-19 patients [2, 3]. It is, therefore, imperative that we reduce the wastage of oxygen wherever possible.

NUMERICAL ANALYSIS OF VALVE STRUCTURE OF HIGH POWER MARINE ENGINE

Valve as an important part of the gas distribution mechanism, is an crucial part of the engine. When the engine works, the valve is subjected to high temperature, high impact, frictional wear and corrosion and other harsh working conditions, and the reliable and durable valve has an important impact on the safety and reliability of the engine. In this paper, a model of four-stroke marine diesel engine valve is used as the research object, and the intake valve set and exhaust valve set models are established respectively. Heat transfer simulation and failure analysis of inlet and exhaust valves of different structures and materials under different operating conditions were carried out using finite element analysis. The results show that the different valve structures and manufacturing materials have different effects on the reliability of the valves; Changing the valve structures and choosing different valve manufacturing materials have a greater impact on the heat transfer and deformation, thus affecting the overall reliability of the valves.

Design, construction, and testing of an accurate low-cost humidistat for laboratory-scale applications

Stable and precise control of humidity is imperative for a wide variety of experiments. However, commercially available humidistats (devices that maintain a constant humidity) are often prohibitively expensive. Here, we present a simple yet effective humidistat for laboratory-scale applications that can be easily and affordably (<€250) constructed based on an Arduino Uno as microcontroller, a set of proportional miniature solenoid valves, a gas washing bottle, and a humidity sensor. The microcontroller implements a PID controller that regulates the ratio of a dry and humid airflow. The design and implementation of the device, including a custom driver circuit for the solenoids, are described in detail, and the firmware is freely available online. Finally, we demonstrate its proper operation and performance through step response and long-term stability tests, which shows settling times of approx. 30 s and an attainable relative humidity range of 10–95%

Aqueductal CSF stroke volume measurements may drive management of shunted idiopathic normal pressure hydrocephalus patients

CSF shunting with adjustable valve is the treatment of idiopathic normal pressure hydrocephalus. The opening pressure valve setting is left to the neurosurgeon’s experience. Aqueductal CSF stroke volume by phase-contrast magnetic resonance measures the CSF passing through the Sylvian aqueduct and it changes with intracranial hydrodynamics. We sought to identify a window of stroke volume differences associated with the best clinical outcome and lowest rate of complications. The records of 69 patients were reviewed. At every clinical check, stroke volume, opening pressure valve, clinical outcome, and CSF overdrainage were analyzed. The correlation between stroke volume differences and negative outcome was also analyzed. The median follow-up was 2.3 years (range 0.3–10.4 years). The odds of negative outcome between two consecutive checks significantly increased by 16% (95%CI 4–28%, p = 0.006). Taking the lowest risk group as reference, the odds ratio of negative outcome was 1.16 (95%CI 0.51–2.63, p = 0.726) for SV differences less than − 37.6 µL, while it was 1.96 (95%CI 0.97–3.98, p = 0.062) for stroke volume changes above + 23.1 µL. Maintaining stroke volume values within a definite range might help maximize clinical benefit and avoid the risk of CSF overdrainage.

The Role of 3D Reconstruction of the Skull in Patients with Suspected Shunt Malfunction

Background: Mechanical shunt malfunction may lead to significant morbidity and mortality. Shunt series assessments help evaluate shunt integrity; however, they are of limited value in the area of the skull due to skull curvature, thickness, and air sinuses. We describe the role of 3D bone reconstruction CT (3DCT) in demonstrating the shunt integrity over the skull, comparing this technique to skull X-rays (SXR). Methods: Data were collected retrospectively for shunted patients with concurrent SXR and 3DCT and for patients presenting with shunt failures at the region of the skull, including clinical course and radiological findings. We compared the SXR and 3DCT findings. The 3DCT was reconstructed from standard diagnostic CT protocols performed during evaluation of suspected shunt malfunction and not thin-slice CT protocols. Results: Forty-eight patients with 57 shunts underwent SXR and 3DCT. Interobserver agreement was high for most variables. Both SXR and 3DCT had a high sensitivity, specificity, and accuracy identifying tubing disconnections (between 0.83 and 1). Full valve type and setting were significantly more accurate based on SXR versus 3DCT (>90 vs. <20%), and valve integrity was significantly more readily verified on 3DCT versus SXR (100 vs. 52%). Conclusions: 3DCT and SXR complement each other in diagnosing mechanical shunt malfunctions over the skull. The main limitation of 3DCT is identification of valve type and settings, which are clearer on SXR, while the main limitation of SXR is a less ability to evaluate valve integrity. 3DCT also enables an intuitive 3D understanding of the shunt tubing over the skull.

Optimal Location of Valves to Improve Equity in Intermittent Water Distribution Systems

This paper proposes a methodology to increase the level of water distribution equity in intermittent water distribution networks (WDNs) with users equipped with private tanks. The methodology makes it possible to identify optimal valve locations and settings to improve the distribution of water among users by rearranging the flow circulation in the network. Two optimization schemes based on the use of NSGA II were developed. The first scheme aims at maximizing the global distribution equity of a WDN through installation of valves fully closed. The second scheme looks also at the levels of supply of the individual nodes of a WDN and includes optimization of both locations and settings of control valves. The two optimization schemes are applied to the case study of a WDN in northern Italy considering a scenario of water shortage. The EPA’s Storm Water Management Model software was used for the pressure-driven simulation of an intermittent WDN. Results of the application of the two optimization schemes highlight the potential for an increase in the global equity of the WDN by installation of a few valves. However, some nodes of the WDN were penalized by the new flow circulation as obtained by solutions provided by the first scheme. In fact, these nodes unacceptably worsen their condition compared to the no-valve scenario. Conversely, solutions obtained with the second scheme allowed demand satisfaction levels to not worsen compared to the no-valve scenario for all nodes.

Computed tomography based assessment of programmable shunt valve settings

IntroductionProgrammable shunt valve settings can sometimes be difficult to assess using classic read-out tools, warranting a skull X-ray. Research questionCan we use available head computed tomography (CT) scans to determine the valve settings, in order to obviate the need for additional skull X-rays? Material and methodsThe valve setting of two different programmable shunts (Codman Certas Plus® and Sophysa Polaris®) were assessed by two blinded observers in 24 patients using 65 head CT scans (slice thickness ≤2 ​mm). Using multi-planar reconstruction (MPR) tools, images were resliced according to the direction of the valve, allowing a direct readout of the valve settings. We validated our CT based method against 32 available skull X-rays. ResultsFor all CT scans it was possible to assess the valve setting. No interobserver variability was found and there was a 100 ​% concordance between the CT based method and skull X-rays. DiscussionCT based assessment of programmable shunt valve settings is feasible and reliable. It may obviate the need for additional skull x-rays when a head CT scan is available. ConclusionsThis technique can reduce radiation exposure and can be applied to historical CT imaging with unknown valve settings.

Experimental and numerical analysis of the rail with the heat control valves

The article presents the results of experimental and numerical tests of a surface heating flow control system consisting of a distribution rail along with the fixed valves set. The flow rates of single and parallel installed valves were measured, their three-dimensional models were prepared and used to make a flow models. The coefficient of kv is computed for a single valve on the rail and for the set of valves. In a flow model geometry the measurements of the test stand elements were considered in order to compare the results. The influence of the addition of the valves to the rail on the flow rate distribution was determined.

Tumor-treating-fields therapy may influence the cerebrospinal fluid shunt valve settings in patients with high-grade glioma

Tumor-treating-fields therapy may influence the cerebrospinal fluid shunt valve settings in patients with high-grade glioma

A magnetic wine cooler prototype

This work presents the design and performance evaluation of a novel magnetic refrigeration unit capable of controlling the temperature of a 31-bottle wine cooler cabinet. The main components of the system are: an active magnetic regenerator composed of eight porous beds of Gd/Gd-Y spheres, a two-pole magnetic circuit responsible for the magnetic field changes, a set of solenoid valves for flow control, and fan-supplied finned tube heat exchangers on the cold and hot sides of the wine cooler apparatus. Synchronization of the magnetic field variation and fluid flow processes was performed using real-time magnetic field measurements. The system was capable of reaching a mean temperature of 10.8 oC inside the retrofitted wine cooler cabinet by generating 27.9 W of cooling capacity for an ambient temperature of 25 oC. The coefficient of performance and second-law efficiency for this operating point were estimated as 0.21 and 1.0%, respectively. When operating at a cabinet temperature of 12.5 oC, the coefficient of performance and second-law efficiency achieved by the magnetic system were 0.38 and 1.6%.

Shunt Catheter Migration Due to Negative Thoracic Pressure

Permanent cerebrospinal fluid diversion has a lengthy list of complications. We present an unusual clinical image of shunt catheter migration. A 54-year-old female had a history of subarachnoid hemorrhage that resulted in communicating hydrocephalus, which needed a ventriculoperitoneal shunt placement. On outpatient follow-up, she was found to have a sunken skin flap that was resistant to raising the shunt valve setting. A radiograph of the shunt system revealed that the peritoneal catheter had migrated into the thoracic cavity. On review of the patient's previous imaging, an area indicative of a minor pleural breach was identified that exposed the catheter to the negative thoracic pressure, which resulted in progressive catheter migration. The patient then underwent removal of the shunt system since her hydrocephalus had resolved. A pleural breach during shunt placement can result in the migration of the shunt catheter into the thoracic cavity under the effect of negative thoracic pressure.

The analysis and prediction of pressure drop oscillation in phase-change cooling systems

Technologies utilizing flow boiling in microchannel evaporators promise high heat fluxes and system efficiencies. However, boiling in microchannels also face significant challenges due to the occurrence of critical heat flux and flow instabilities, such as pressure drop oscillations. Since several system parameters can cause these issues in a two-phase system, identifying these parameters in advance can help avoid these challenges. This study investigates pressure drop oscillation in a pumped liquid cycle using both experiments and numerical modeling. The model utilizes the moving boundary modeling approach to predict system stability and capture the oscillation characteristics. Both experiments and the model determine how different combinations of system parameters, like the valve settings, pump speed, and evaporator heat load, can affect system stability. The study also relates the change in flow oscillation characteristics to the system's supply and demand pressures. This study examines why certain combinations of system parameters induce flow instability and provide ways to mitigate this challenge. A general agreement between the model and experiments also demonstrates the accuracy of the moving boundary modeling approach. Consequently, this modeling approach can be useful in predicting instability, optimizing the system performance, and developing active control strategies for cooling technologies relying on flow boiling in microchannels.

Dynamic control of microchannel cooling system with unanticipated evaporator heat loads

This study presents a control strategy for electronic cooling systems incorporating microchannel evaporators that experience unanticipated and significant heat load variations. It complements prior studies that focus primarily on the steady operation of two-phase systems facing static heat loads. This study's overall objective is to maintain a fixed evaporator temperature, enable high system efficiency, and avoid critical heat flux (CHF) despite the presence of transient and unexpected variations in heat loads. In this regard, we developed a moving boundary model to account for the presence of single-phase and two-phase flow in the evaporator and account for their respective flow and heat transfer characteristics. We use this model to identify optimum operating conditions for different evaporator heat loads that avoid CHF and correspond to a high COP. Since the changes in the heat loads are unanticipated, we design a disturbance observer based on the optimum operating conditions to estimate the unanticipated evaporator heat loads, which could serve as the feedforward control signal for system inputs such as pump-speed and valve settings. This study demonstrates how the system can maintain a constant evaporator temperature when it experiences a three-fold increase in the heat load. We also extend this study to two evaporators operating in parallel and experiencing unanticipated and asynchronous variations in the evaporator heat load. Our results show that the system with a disturbance observer and controller can maintain a fixed evaporator temperature even under significant heat load variations.

Surrogate-Based Prediction and Optimization of Multilateral Inflow Control Valve Flow Performance with Production Data

Summary Smart completions enable physical measurements over space and time, which provides large volumes of information at unprecedented rates. However, optimizing inflow control valve (ICV) settings of smart multilateral wells is a challenging task. Traditionally, ICV field tests, evaluating well performance at different ICV settings, are conducted to observe flow behavior and configure ICVs; however, this is often suboptimal. This study investigated a surrogate-based optimization algorithm that minimizes the number of ICV field tests required, predicts well performance of all unseen combination of ICV settings, and determines the optimal ICV setting and net present value (NPV). A numerical model of a real offshore field in Saudi Arabia was used to generate scenarios involving a two-phase (oil and water) reservoir with trilateral producers. Multiple scenarios were examined with variations in design parameters, mainly well count, placement, and configuration. Eight discrete settings were assumed to match the commonly installed ICV technology, where all possible scenarios were simulated to establish ground truth. The investigation considered three major algorithmic components: sampling, machine learning, and optimization. The sampling strategy compared physics-based initialization, space-filling sampling, and triangulation-based adaptive sampling. A cross-validated neural network was used to fit a surrogate (in this case, machine learning algorithm) dynamically, whereas enumeration was adopted for optimization to avoid errors arising from using common optimizers. This study evaluated two sampling techniques: space-filling and adaptive sampling. The latter was found superior in capturing reservoir behavior with the smallest number of simulation runs (i.e., ICV field tests). Algorithm performance was evaluated based on the number of ICV field tests required to exceed an R2 threshold of 90% on all unseen scenarios and match the optimal ICV settings and NPV. Surface and downhole flow profile prediction and optimization were achieved successfully using this approach. To determine the diminishing value of additional ICV field tests, the triangulation sampling loss was used as a stoppage criterion. When running the algorithm on a single producer for both surface and downhole oil and water flow prediction, the algorithm required only 6 and 11 ICV field tests to achieve 80% and 90% R2 across the different cases of this real reservoir model. Fishbone wellbore configurations were found to pose a more challenging task because changes in any ICV pressure decrease affects multiple laterals simultaneously, which increases the level of interdependence. The resultant surrogate was used to decide on the optimal settings of ICV devices and effectively predict the NPV. Surrogates, in this approach, are statistical proxies of the targeted ground-truth production function. Further improvement was accomplished through adaptively sampling and fitting surrogates to predict NPV explicitly, where NPV predictions were generated with nearly 95% R2 given only 10 ICV field tests. Using adaptive sampling and machine learning proved effective in the prediction of surface and downhole flow profiles and optimization of smart wells. The method further allows for dynamically optimizing field strategy in a reinforcement learning setting where production data are used continuously to further improve the prediction performance.

Interactions between programmable shunt valves and magnetically controlled growing rods for scoliosis.

Although the advent of magnetic growing rod technology for scoliosis has provided a means to bypass multiple hardware lengthening operations, it is important to be aware that many of these same patients have a codiagnosis of hydrocephalus with magnet-sensitive programmable ventricular shunts. As the magnetic distraction of scoliosis rods has not previously been described to affect the shunt valve setting, the authors conducted an investigation to characterize the interaction between the two devices. In this ex vivo study, the authors carried out 360 encounters between four different shunt valve types at varying distances from the magnetic external remote control (ERC) used to distract the growing rods. Valve settings were examined before and after every interaction with the remote control to determine if there was a change in the setting. The Medtronic Strata and Codman Hakim valves were found to have setting changes at distances of 3 and 6 inches but not at 12 inches. The Aesculap proGAV and Codman Certas valves, typically described as MRI-resistant, did not have any setting changes due to the magnetic ERC regardless of distance. Although it is not necessary to check a shunt valve after every magnetic distraction of scoliosis growing rods, if there is concern that the magnetic ERC may have been within 12 inches (30 cm) of a programmable ventricular shunt valve, the valve should be checked at the bedside with a programmer or with a skull radiograph along with postdistraction scoliosis radiographs.