Real-time Pressure Measurement Research Articles

Automated Workflow Uses Pressure, Rate Measurements for Well Monitoring

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 218470, “A New Automated Workflow for Well Monitoring Using Permanent Pressure and Rate Measurements,” by Anton Shchipanov, SPE, NORCE; Boyu Cui, SPE, University of Stavanger; and Vitaly Starikov, SPE, Heriot-Watt University, et al. The paper has not been peer reviewed. _ The complete paper describes an integrated workflow for automated well monitoring using pressure and rate measurements obtained with permanent gauges and flowmeters. The workflow is based on time-lapse pressure transient analysis (PTA) and integrates the following components: virtual flowmetering (VFM), transient identification, feature extraction and pattern recognition in transient pressure responses, and assessment of well performance based on PTA metrics. The methodology behind the workflow combines different physics-informed and data-driven methods described in the paper. A New Workflow for Automated Well Monitoring The concept of the automated workflow described in the complete paper has been suggested in the literature. The workflow consists of four main steps (Fig. 1), and integrates the following components: - VFM - Pressure transient identification - PTA feature extraction and time-lapse pattern recognition - PTA metrics to obtain the well-performance profile VFM. The well flow rate is often measured more sparsely than its bottomhole or wellhead pressure for many reasons. However, the permanent downhole or wellhead gauges, when installed in a well, provide high-frequency real-time pressure and temperature measurements. This disparity in the pressure- and rate-measurement sampling rates is a problem for PTA, which requires accurate and synchronized input for flow rates in line with the pressure time series. VFM helps reconstruct missing flow-rate measurements using available pressure measurements. The automated well-monitoring workflow described in this paper would benefit from integration of a relatively simple but robust and scalable VFM model having modest input-data requirements. The steady-state vertical-lift-performance-based VFM model was chosen for use by the authors after testing. The model uses only the bottomhole and wellhead pressure difference, which fits well with the automated workflow requirements. Put simply, the VFM-developed algorithm identifies the suitable pressure and flow-rate samples to train the VFM model; estimates, filters, and verifies the evolution of the model coefficients; and predicts the missing flow-rate values using the pressure measurements where available. This prediction applies only to the time when the well is flowing; as for shut-in periods, the algorithm assigns zero rate values. Transient Identification. Proper transient identification is crucial for PTA because accurate identification of the starting break point of a transient and sequential synchronization with corresponding rate governs the reliability of PTA interpretation results. This is important not only for the transient in question but also for the well history preceding the transient. In the latter case, proper transient identification may help in reliable rate time allocation throughout the well history for common cases of uncertain rates. The workflow of the extended method consists of two main stages. First, the breakpoints indicating start and end of shut-in transients are detected using the topographic prominence max rotation (TPMR) method. This automatically provides detection of flowing transients between the shut-ins identified. Second, the breakpoints of multirate periods (assuming stepwise rate changes) are detected within the long flowing transients using the local minimum in rotation (LMIR) method. As a result, the well pressure history is divided into sequential flowing and shut-in transients, also differentiating flowing transients governed by stepwise rate changes. Neither TPMR nor LMIR methods require denoising, so raw data from permanent gauges may be used without any preprocessing.

Study on the Effect of Three-dimensional Reconstruction Technique Based on Human Gait Plantar Transient Data on Rehabilitation of Patients with Abnormal Foot Arch

This research employs non-contact plantar 3D data scanning and gait analysis methodologies to establish a rehabilitation assistance system tailored for foot arch anomalies. The system utilizes a non-contact plantar 3D data model to mitigate dysfunctions within the plantar skeletal-muscular system. Its objectives include facilitating personalized remote diagnosis of foot arch anomalies, enabling patients to monitor their rehabilitation progress, and supporting at-home rehabilitation efforts. A dataset comprising 124 cases of physiological foot arch anomalies in adults aged 18 and above was collected and analyzed. The findings demonstrate the system’s flexibility, high spatial resolution, personalization, and innovation. Notably, the system achieves real-time measurement of positive pressure and shear force distribution at the plantar interface, facilitates the construction of accurate geometric models, and yields high-quality plantar three-dimensional coordinate data. This research contributes theoretical and technical underpinnings for the application of footwork anomaly diagnosis and correction.

A Custom-Tailored Multichannel Pressure Monitoring System Designed for Experimental Surgical Model of Abdominal Compartment Syndrome.

In experimental medicine, a wide variety of sensory measurements are used. One of these is real-time precision pressure measurement. For comparative studies of the complex pathophysiology and surgical management of abdominal compartment syndrome, a multichannel pressure measurement system is essential. An important aspect is that this multichannel pressure measurement system should be able to monitor the pressure conditions in different tissue layers, and compartments, under different settings. We created a 12-channel positive-negative sensor system for simultaneous detection of pressure conditions in the abdominal cavity, the intestines, and the circulatory system. The same pressure sensor was used with different measurement ranges. In this paper, we describe the device and major experiences, advantages, and disadvantages. The sensory systems are capable of real-time, variable frequency sampling and data collection. It is also important to note that the pressure measurement system should be able to measure pressure with high sensitivity, independently of the filling medium (gas, liquid). The multichannel pressure measurement system we developed was well suited for abdominal compartment syndrome experiments and provided data for optimizing the method of negative pressure wound management. The system is also suitable for direct blood pressure measurement, making it appropriate for use in additional experimental surgical models.

Research and Test on the Device of Downhole Near-Bit Temperature and Pressure Measurement While Drilling

The accurate acquisition of downhole engineering parameters, such as real-time pressure and temperature measurements, plays a crucial role in mitigating drilling risks and preventing accidents. In this study, we present the design of a real-time data acquisition and transmission system for drilling operations. The system utilizes a near-bit measurement method to simultaneously measure downhole parameters, including mud pressure and temperature. By analyzing the pressure and temperature frequencies obtained from a quartz crystal pressure gauge and compensating for temperature effects, accurate pressure values are obtained. The resistance value of a PT1000 sensor is measured, and a second-order fitting is performed using laboratory scale coefficients to determine the temperature values. The data acquisition system employs an advanced microcontroller as the main control chip, along with an A/D conversion chip. Additionally, signal amplification, data storage modules, data transmission modules, and relevant peripheral circuits are designed. The field tests were conducted in the 4605~4620 m well section of well Qing 2-76 in the Yumen Oilfield. The results demonstrate stable transmission signals and accurate decoding, enabling the real-time monitoring of pressure and temperature. The tests yielded favorable outcomes, providing a tangible means to analyze the actual operating conditions of the downhole drill string.

297 Pressure in the Operating Room (OR): another Possible Contributor to Hospital Acquired Pressure Injuries (HAPIs)

Abstract Introduction Burn patients are at risk for HAPIs. An unexamined factor that may contribute to HAPI development is the effect of pressure from the OR table. Burn patients often require multiple prolonged surgical procedures. The purpose of this study was to measure pressure on the buttocks and sacral area during burn OR procedures under general anesthesia (GA). This has not been previously assessed in the burn literature. Methods Prospective study of consecutive adult burn patients admitted to an ABA-verified burn center who required surgery under GA between 06/01/22 and 08/12/22. We studied only cases that were supine, including those with both legs down (BLD), one leg suspended (one leg up: 1LU) or both legs suspended (two legs up: 2LU). Pressures on the buttocks and sacral area were measured using a commercial sensor mat which sent continuous real-time pressure measurements wirelessly to a laptop computer. Thousands of individual pressure measurements were integrated and organized to show average and peak pressures over repetitive 10-minute intervals during the entire operative procedure. Also, a continuous visual color-coded map of the sacral and buttock areas showing high ( >75 mmHg-red), medium (10-75 mmHg -yellow) and low ( < 10 mmHg -blue/green) pressures was created for each procedure. Results are shown as mean ± SD. Results Recordings were completed in 41 procedures (35 acute excision & grafting, 5 reconstructive, 1 tracheostomy) among 28 patients ( 48 ± 17 yrs, % TBSA burn 19 ± 17, weight 80 ± 20 kg, BMI 27 ± 6). During BLD, over 125 ± 81 min, the average pressure (Pave) was 47 ± 7 mmHg and peak pressure (Ppeak) reached 82 ± 23 mmHg. During isolated 1LU periods, Pave was 53 ± 9 mmHg over 74 ± 58 minutes with a Ppeak of 93 ± 23 mmHg and during isolated 2LU, Pave and Ppeak were respectively 55 ± 10 mmHg over 78 ± 40 min and 98 ± 23 mmHg. Both Pave and Ppeak increased significantly from procedures with BLD to 1LU to 2LU (p< 0.001). Pave crept steadily upwards during both BLD and 1LU or 2LU procedures (Figure). We observed that Pave had a positive relationship with weight, regardless of operative position. Conclusions Prolonged moderate to high pressures are exerted on the sacral and buttock areas, especially with one or both legs suspended, during burn surgery. These novel observations suggest that pressure from the OR table could contribute to HAPI development. Applicability of Research to Practice With this risk identified, interventions to lower or interrupt pressure exposure during burn surgery should be identified next.

In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty.

Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage anteromedial osteoarthritis (AMOA). The key to UKA is the flexion-extension gap balance, which is closely related to postoperative complications such as bearing dislocation, bearing wear, and arthritis progression. The traditional gap balance assessment is performed by indirectly sensing the tension of the medial collateral ligament by a gap gauge. It relies on the surgeon's feel and experience, which is imprecise and difficult for beginners. To accurately assess the flexion-extension gap balance of UKA, we developed a wireless sensor combination consisting of a metal base, a pressure sensor, and a cushion block. After osteotomy, the insertion of a wireless sensor combination allows the real-time measurement of intra-articular pressure. It accurately quantifies the flexion-extension gap balance parameters to guide further femur grinding and tibia osteotomy, to improve the accuracy of gap balance. We conducted an in vitro experiment with the wireless sensor combination. the results showed that there was a difference of 11.3 N after applying the traditional method of flexion-extension gap balance performed by an experienced expert.

Review of Different Methods for Identification of Transients in Pressure Measurements by Permanent Downhole Gauges Installed in Wells

Permanent downhole gauges (PDG) are massively installed in injection and production wells operated in different industries such as oil and gas, geological CO2 storage, and the geothermal industry. These gauges provide a vast amount of real-time pressure measurements. The pressure measurements may be divided into periods with a predominantly monotonic change of pressure in response to a sudden change of rate, called transients. These transients are caused by well operations, such as variation of injection or production rate and well shut-ins. Transient identification is one of the important steps in processing and interpreting the PDG data. Traditional transient identification is performed by processing and analyzing with human involvement, which is a step in post-operation well analysis. In modern well surveillance technology, permanent and reliable data transmission from the wellbore to the surface provide the possibility to analyze well performance in real time or proactively. So automated transient identification is a practical demand, but a challenge at the same time. This article starts with the definition of a transient, then reviews and compares seven methods for transient identification proposed by previous works available in the literature. A comparative analysis of these methods is carried out accounting for the detection algorithm and procedure, results of testing, and general positive and negative sides of performance and application of these methods. The results of this review facilitate further developments of field data interpretation techniques by the R&D community and academia and may help in the selection of a proper method for further application in well surveillance workflows developed in the industry.

Real-time measurement of stapes motion and intracochlear pressure during blast exposure

Blast-induced auditory injury is primarily caused by exposure to an overwhelming amount of energy transmitted into the external auditory canal, the middle ear, and then the cochlea. Quantification of this energy requires real-time measurement of stapes footplate (SFP) motion and intracochlear pressure in the scala vestibuli (Psv). To date, SFP and Psv have not been measured simultaneously during blast exposure, but a dual-laser experimental approach for detecting the movement of the SFP was reported by Jiang et al. (2021). In this study, we have incorporated the measurement of Psv with SFP motion and developed a novel approach to quantitatively measure the energy flux entering the cochlea during blast exposure.Five fresh human cadaveric temporal bones (TBs) were used in this study. A mastoidectomy and facial recess approach were performed to identify the SFP, followed by a cochleostomy into the scala vestibuli (SV). The TB was mounted to the “head block”, a fixture to simulate a real human skull, with two pressure sensors – one inserted into the SV (Psv) and another in the ear canal near the tympanic membrane (P1). The TB was exposed to the blast overpressure (P0) around 4 psi or 28 kPa. Two laser Doppler vibrometers (LDVs) were used to measure the movements of the SFP and TB (as a reference). The LDVs, P1, and Psv signals were triggered by P0 and recorded simultaneously.The results include peak values for Psv of 100.8 ± 51.6 kPa (mean ± SD) and for SFP displacement of 72.6 ± 56.4 μm, which are consistent with published experimental results and finite element modeling data. Most of the P0 input energy flux into the cochlea occurred within 2 ms and resulted in 10–70 μJ total energy entering the cochlea. Although the middle ear pressure gain was close to that measured under acoustic stimulus conditions, the nonlinear behavior of the middle ear was observed from the elevated cochlear input impedance.For the first time, SFP movement and intracochlear pressure Psv have been successfully measured simultaneously during blast exposure. This study provides a new methodology and experimental data for determining the energy flux entering the cochlea during a blast, which serves as an injury index for quantifying blast-induced auditory damage.

Large Permeameter for Continuing Erosion Filter Tests

Abstract The Continuing Erosion Filter (CEF) test and criteria were developed by Foster and Fell to assess severities of internal erosion of an existing embankment dam whose filter does not satisfy modern filter design criteria developed by Sherard and Dunnigan. Those criteria were developed from laboratory tests on materials that may not be directly applicable to the widely graded filter materials. To address this issue, a large diameter (300 mm) rigid-wall permeameter was constructed to assess the internal erosion of zoned embankment dams constructed of widely graded filter materials. The large permeameter allows for testing of embankment dam fill materials up to a maximum particle size of 37.5 mm. A commissioning test program was conducted to verify the test equipment and testing methodology used in this study. Two CEF test results from the test program are reported in this paper to demonstrate the novel features of the permeameter cell design and its test setup. These features include a split-cell design for ergonomic function, real-time outflow rate measurement, inflow and filter specimen water pressure measurements, and erosion loss measurement. A wet method to estimate erosion loss was proposed as an alternative to the traditional oven-drying method.

A microfluidic approach to investigate the effects of bacteria deposition in porous media containing randomly packed microbeads via real-time pressure measurement

A microfluidic approach to investigate the effects of bacteria deposition in porous media containing randomly packed microbeads via real-time pressure measurement

Rapid and wide-range pressure measurement at high-temperature using an intensity-compensation interrogation method

Rapid-interrogation of MEMS Fabry-Perot (F-P) sensor is a promising method for real-time pressure measurement in high-temperature environments, but this approach is rather challenging because of the temperature-induced influence on signals. To solve this problem, we first present (to our best knowledge) a novel intensity-compensation interrogation method for wide-range pressure monitoring from 25 °C to 700 °C. In the proposed method, Optical signal passing through the beam splitter is employed as a reference, which is applied to compensate the temperature-induced intensity fluctuations of the signals without affecting the orthogonality. Experimental results verifies that the proposed compensation technique reduces the intensity fluctuations of the two orthogonal signals by 95.1% and 95.7%, respectively, which significantly improves the stability of signals. Additionally, results also demonstrate that the proposed method achieves the real-time pressure measurement of 0.1 - 5 MPa at 25 °C and 0.1 - 3 MPa from 200 °C to 700 °C, with interrogation rate up to 5 kHz. The proposed intensity-compensation interrogation method overcomes the obstacle of wide-range pressure monitoring in high-temperature based on MEMS F-P sensor, and opens the way for real-time pressure measurement in harsh environments.

Piezoresistive Conductive Microfluidic Membranes for Low-Cost On-Chip Pressure and Flow Sensing.

Over the last two decades, the field of microfluidics has received significant attention from both academia and industry. Each year, researchers report thousands of new prototype devices for use in a broad range of environmental, pharmaceutical, and biomedical engineering applications. While lab-on-a-chip fabrication costs have continued to decrease, the hardware required for monitoring fluid flows within the microfluidic devices themselves remains expensive and often cost-prohibitive for researchers interested in starting a microfluidics project. As microfluidic devices become capable of handling complex fluidic systems, low-cost, precise, and real-time pressure and flow rate measurement capabilities have become increasingly important. While many labs use commercial platforms and sensors, these solutions can often cost thousands of dollars and can be too bulky for on-chip use. Here we present a new inexpensive and easy-to-use piezoresistive pressure and flow sensor that can be easily integrated into existing on-chip microfluidic channels. The sensor consists of PDMS–carbon black conductive membranes and uses an impedance analyzer to measure impedance changes due to fluid pressure. The sensor costs several orders of magnitude less than existing commercial platforms and can monitor local fluid pressures and calculate flow rates based on the pressure gradient.

A Novel Standardized Peripheral Nerve Transection Method and a Novel Digital Pressure Sensor Device Construction for Peripheral Nerve Crush Injury.

Peripheral nerve injury (PNI) is common in all walks of life, and the most common PNIs are nerve crush and nerve transection. While optimal functional recovery after crush injury occurs over weeks, functional recovery after nerve transection with microsurgical repair and grafting is poor, and associated with permanent disability. The gold-standard treatment for nerve transection injury is microsurgical tensionless end-to-end suture repair. Since it is unethical to do experimental PNI studies in humans, it is therefore indispensable to have a simple, reliable, and reproducible pre-clinical animal model for successful evaluation of the efficacy of a novel treatment strategy. The objective of this article is two-fold: (A) To present a novel standardized peripheral nerve transection method in mice, using fibrin glue for modeling peripheral nerve transection injury, with reproducible gap distance between the severed nerve ends, and (B) to document the step-wise description of constructing a pressure sensor device for crush injury pressure measurements. We have successfully established a novel nerve transection model in mice using fibrin glue, and demonstrated that this transection method decreases surgical difficulties and variability by avoiding microsurgical manipulations on the nerve, ensuring the reproducibility and reliability of this animal model. Although it is quite impossible to exactly mimic the pathophysiological changes seen in nerve transection with sutures, we hope that the close resemblance of our novel pre-clinical model with gold-standard suturing can be easily reproduced by any lab, and that the data generated by this method significantly contributes to better understanding of nerve pathophysiology, molecular mechanisms of nerve regeneration, and the development of novel strategies for optimal functional recovery. In case of peripheral nerve crush injury, current methods rely on inter-device and operator precision to limit the variation with applied pressure. While the inability to accurately quantify the crush pressure may result in reduced reproducibility between animals and studies, there is no documentation of a pressure monitoring device that can be readily used for real-time pressure measurements. To address this deficit, we constructed a novel portable device comprised of an Arduino UNO microcontroller board and force sensitive resistor (FSR) capable of reporting the real-time pressure applied to a nerve. This novel digital pressure sensor device is cheap, easy to construct and assemble, and we believe that this device will be useful for any lab performing nerve crush injury in rodents.

Real-Time Pressure Measurement Method Based on Rapid Phase Demodulation of Multi-Cavities F-P Sensor

In this paper, a novel method for real-time pressure measurement based on rapid phase demodulation of multi-cavities Fabry-Perot (F-P) sensor is proposed. In the demodulation system, according to the principle of low-coherence interference, birefringent crystals, polarizers and analyzers are used to obtain orthogonal signals, which can significantly reduce the influence of irrelevant F-P cavities on the demodulation result, indicating that the method is suitable for rapid demodulation of F-P sensors containing multiple cavities. Experimental results also confirm that the method is able to demodulate the signal of F-P MEMS sensor in real-time. By using the four-quadrant inverse tangent operation instead of differential cross multiplier algorithm to calculate the phase of the F-P sensor, pressure in the range of 110 kPa −200 kPa is measured in real-time, with the demodulation rate of 5 kHz. The measurement errors are less than 0.41 kPa, and the standard deviations are less than 0.25 kPa. The proposed method provides a new idea for the rapid demodulation of F-P sensors containing multiple cavities, and has great potential in promotion and applications of real-time pressure measurement, such as dynamic pressure of aero-engines, shock waves and so on.

Measuring System Design and Experiment for Ground Pressure on Seeding Skateboard of Rice Direct Seeding Machine

Acquiring real-time ground pressure measurements from the surface of the soil in working parts of paddy fields is a challenging task. The real-time data can be used to monitor the changing state of the ground pressure of the working parts in a paddy field. To effectively reduce the accumulation of choked mud at the front end of the seeding skateboard and the contact adhesion between the skateboard and the paddy soil, a ground pressure measuring device suitable for paddy fields was designed. The device uses an Arduino controller, combined with Internet of things technology and wireless measurement technology. It can measure the pressure from 16 measuring points at the same time and transmit the measurement data to the computer remotely through the Internet of things technology, which greatly reduces the labor intensity of measuring personnel in the muddy paddy field. Analysis of the data showed that the forward tilt angle, ground pressure, and forward resistance of the seeding skateboard also increased with the increase of forward speed and vertical load. In addition, the distribution law of the ground pressure between the skateboard and the paddy soil was obtained. The conclusions show that the ground pressure measurement system can work stably in the paddy field and the measured data can be wirelessly transmitted to the computer and mobile phone.

Locating the Isolator Shock-Train Leading Edge with Limited Pressure Information

Real-time detection and control of the isolator shock-train leading edge (STLE) is important to the performance of high-speed air-breathing engines, such as dual-mode scramjets. Typically, the STLE location is determined using wall static-pressure measurements, but there are often restrictions on the placement and overall number of the pressure transducers, reducing the viability and accuracy of such approaches. To address these issues, we introduce the adaptive pressure profile (APP) method for estimating the STLE location. This method does not require extensive prior characterization of the isolator or engine model. Instead, it uses real-time pressure measurements from a small number of transducers to adaptively learn the isolator pressure profile and subsequently uses this deduced profile to estimate the STLE location in a data-driven manner. The APP method works well in situations with sparse transducer placement. It produces accurate estimates when the STLE location is 1) not bounded by two or more transducers or 2) between two transducers that are several isolator duct heights apart. We demonstrate the efficacy of the APP method using simulations and experimental data from direct-connect isolator models. This validation shows that the APP method is accurate and robust for different flow regimes, transducer configurations, and model geometries.

Development of a Continuous Blood Pressure Measurement and Cardiovascular Multi-Indicator Platform for Asian Populations by Using a Back Propagation Neural Network and Dual Photoplethysmography Sensor Signal Acquisition Technology

This study proposed a measurement platform for continuous blood pressure estimation based on dual photoplethysmography (PPG) sensors and a back propagation neural network (BPNN) that can be used for continuous and rapid measurement of blood pressure and analysis of cardiovascular-related indicators. The proposed platform measured the signal changes in PPG and converted them into physiological indicators, such as pulse transit time (PTT), pulse wave velocity (PWV), perfusion index (PI), heart rate (HR), and pulse wave analysis (PWA); these indicators were then fed into the BPNN to calculate blood pressure. The hardware of the experiment comprised 2 PPG components (i.e., Raspberry Pi 3 Model B and analog-to-digital converter [MCP3008]), which were connected using a serial peripheral interface. The BPNN algorithm converted the stable dual PPG signals acquired from the strictly standardized experimental process into various physiological indicators as input parameters and finally obtained the systolic blood pressure (SBP) and diastolic blood pressure (DBP). To increase the robustness of the BPNN model, this study input data of 100 Asian participants into the training database, including those with and without cardiovascular disease, each with a proportion of approximately 50%. The experimental results revealed that the mean and standard deviation of SBP were2.23±2.24 mmHg, with a mean squared error of 3.15 mmHg. The mean and standard deviation of DBP was3.5±3.53 mmHg, with a mean squared error of 4.96 mmHg. The proposed real-time blood pressure measurement system exhibited a mean accuracy of 98.22% and 95.58% for SBP and DBP, respectively.

Abstract No. 443 A proposed device for the prediction of a quantitative endpoint for transarterial embolization from real-time pressure measurements

We propose a device composed of a catheter to deliver embolic agent as well as a pressure sensor to monitor the extent of occlusion. By continually measuring intravascular pressure, this device allows for consistent, objective determination of a clinically relevant procedural endpoint; and prevention of anterograde reflux and off-target embolization.

Motion mechanism study on the valve disc of an ultra-high pressure reciprocating pump

Efficiency of reciprocating pumps depends on the performance of their valves. In order to find a breakthrough point of prolonging the valve service life, research on the valve motion mechanism of an ultra-high pressure reciprocating pump has been carried out in this paper. A valve motion mathematical model is firstly established based on the mechanical equilibrium equation and the fluid continuity equation. In order to record the real valve motion in experiments, a detection system specifically designed for valve lift real-time measurement of ultra-high pressure fracturing pumps has been built. Then results of valve lift, velocity and acceleration obtained by the model and the experiment are compared and analysed in detail. Results show that a whole valve motion in a single motion cycle can be divided into four stages. Considering the crank-connecting rod ratio makes the valve motion model predict closer results to the truth in the maximum flow stage. An accurate opening lag angle has the similar benefit in the rapid opening stage. There are three individual motion phases in the rapid opening stage, which will not be found without consideration of inertial force of valve disc and changing spring force. The findings should make an important contribution to understanding the valve motion mechanism of ultra-high pressure reciprocating pumps and further investigation is encouraged.

The Innovative Use of Ureter Catheter in the Surgery of Obstructive Uropathy.

Purpose Relieving obstruction and protecting renal function are the main therapeutic purposes of obstructive uropathy which often involve surgical treatment, and the ureter catheter is one of the surgical instruments commonly used in surgery. We aimed to explore the innovative use of a ureter catheter in the surgery of obstructive uropathy. Methods We used a ureteral catheter to innovate the surgical procedure of the most common causes of obstructive uropathy: ureteral calculi and stricture, establishing an internal circulation system (ICS), proposing a three-step dilatation method, and reviewing their effects on patients. Furthermore, we introduced a simple real-time intrapelvic pressure measurement device to monitor intrarenal pressure during operation. Results Postoperative laboratory examination showed that blood CRP, leukocyte neutrophil level, changes in the hemoglobin, urine occult blood, and positive rate of urine culture in the ICS group are significantly lower than those in the control group, corresponding to a lower incidence of bleeding and infection-related complications clinically. A three-month follow-up revealed 1/3 rate of ureteral stricture in the ICS group comparing to the control. We applied the three-step dilatation in patients with severe stenosis in which the balloon could not pass; the overall effective rate was 90.9%. The pressure of the renal pelvis was displayed on the monitor in real time. The surgeon could estimate the degree of filling of the renal pelvis and adjust the intake volume through the data. Conclusion The innovative application of ureteral catheters in the operation of obstructive uropathy can realize the real-time monitor of intraoperative renal pelvis pressure, reduce the incidence of lithotripsy postoperative complications, and expand the indications of balloon dilatation in ureteral stricture, which has certain clinical significance.