Stable Pressure Research Articles

Pipe Insertion Technique for Slug Attenuation in a Downwardly Inclined Pipeline

Slug flow is more prevalent in downwardly inclined pipelines and it is important to develop effective and suitable mitigation strategies to reduce its occurrence and enhance stable flow. In this work, the application of pipeline insertion was proposed to reduce slugging in pipeline. A simulation based approach was adopted and a model with smaller pipe sizes of 3.958-inch, 1.995-inch and 6-inch diameter, inserted near the pipeline riser system. The developed model was run for 2 hours to monitor the harsh nature of the slug on the total liquid volume flow, the pressure at the pipeline riser outlet, surge liquid volume and accumulated liquid volume. The result shows a stable liquid production of approximately 3797.08bbl/day and 3798.44bbl/day for the 3.958-inch and 1.995-inch diameter pipe size, while the total liquid flow oscillated between 7366.45bbl/day and 1.917.37bbl/day, and repeated at 0.22 hours. There was a pressure buildup and later steady at 761.978 psia and 762.127 psia for the 3.958-inch and 1.995-inch diameter pipe at the riser base while the 6-inch diameter pipe was fluctuating. Smaller diameter pipe of 3.958-inch and 1.995-inch gave a stable fluid pressure of 725.196 psia at the riser top (outlet) .Therefore, smaller diameter pipe is the best to insert since there was no cyclic fluctuation of pressure at the riser top, which can lead to severe slugging.

Bispectral Index-Monitored Anesthesia Induction in Older Adults Undergoing Elective Surgery: Comparing Ciprofol and Propofol in a Prospective, Single-Center, Double-Blind, Randomized Controlled Study.

Ciprofol, a new sedative anesthetic developed in China, offers rapid onset and recovery, reduced injection pain, and stable circulation. However, its effect on blood pressure during anesthesia induction in older adults remains unclear. To compare the effects of propofol and ciprofol on hypotension induced by general anesthesia in older adults. This prospective, single-center, double-blind, randomized, controlled clinical study enrolled 117 older adults undergoing surgery. Patients in the ciprofol group (group C) received an intravenous injection of ciprofol (0.3 mg/kg, n=57), while the propofol group (group P) received an intravenous injection of propofol (1.5 mg/kg, n=58). The primary outcome was the incidence of hypotension (mean arterial pressure (MAP) decreased by > 30% from baseline or MAP< 65mmHg). Secondary outcomes included induction success rate (bispectral index (BIS) value ≤60 and Modified Observer's Assessment of Alertness/Sedation Scale (MOAA/S) score ≤1), injection pain, number of drug additions, time to BIS 60, time to eyelash reflex disappearance, blood pressure changes, incidence of hypertension, tachycardia and BIS values before and after administration. The incidence of induced hypotension was 26.3% (15/57) in group C and 48.3% (28/58) in group P (OR=0.383, 95% CI:175-0.837, P =0.015). Group C had significantly lower injection pain incidence (5.3% vs 20.7%, OR=0.213, 95% CI: 0.057-0.801, p=0.014). Both groups had a 100% induction success rate, with no significant difference in the number of additional doses. Post-intubation hypertension and tachycardia incidence were not significantly different. Group C showed less blood pressure decrease during induction and a deeper anesthesia level. Compared to propofol, ciprofol reduces the incidence of induced hypotension in older adults and maintains more stable blood pressure during induction. Additionally, ciprofol reduces injection pain and provides a good depth of anesthesia, making it a safe and effective option for anesthesia induction in older adults. ChiCTR2200066053.

Experimental analysis of a hybrid thermochemical cycle driven by intermediate grade heat sources for energy storage and combined cold and work productions

This paper presents an experimental study of a hybrid thermochemical cycle for the simultaneous cogeneration of cold and mechanical power, and thermal storage based on medium temperature sources. This concept is based on the integration of an expander machine on the reactive gas flow between the evaporator and the reactor to allow mechanical work production. The paper shows the proof of concept of this hybridization by continuous mechanical production and cold during the whole production phase: 68.33 kJ mechanical energy and 15.18 MJ cold, stable pressure ratio at the expander (around 1.3) and stable rotational speed (around 400 rpm). The prototype conception and design are detailed. The integration of the expander creates a pressure difference between the evaporator and the reactor (contrary to a classical thermochemical cycle), and thus an experimental sensitivity study investigating the effect of the cold production temperature at the evaporator (which defines the inlet pressure of the expander) on the mechanical production of the prototype and its dynamics is done. This allowed to analyze the strong coupling between the reactor and the expander in different operating conditions, experimentally and from a theoretical point of view. Indeed, the identified limitations of these two main components, it is worth mentioning that this is the first hybrid thermochemical prototype with stable output productions. The prototype works properly by providing continuous mechanical production during the whole production phase under different cold temperatures and constant electrical load, in comparison with what was found in the literature.

Use of esketamine for tracheoscopic drug injection: a randomized controlled trial.

Sufentanil may induce hypotensive bradycardia and other adverse reactions in elderly patients during anesthesia, while esketamine exhibits sedative and analgesic effects with minimal impact on respiration and circulation. The objective of this study was to investigate the impact of these two anesthetics on vital signs in patients undergoing bronchoscopy and lavage under general anesthesia. This study was a randomized controlled trial with a parallel design. A total of 100 patients aged ≥60 years with ASAI or II who were undergoing bronchoscopy and lavage were randomly assigned to two groups: group A (esketamine, n = 50) and group B (sufentanil, n = 50). During anesthesia induction, both groups received intravenous infusion of propofol at a dose of 1.5 mL/kg and atracurium. In group A, esketamine at a dose of 0.3 mg/kg was injected; in group B, sufentanil at a dose of 0.2 μg/kg was injected intravenously. Subsequently, a laryngeal mask was inserted and connected to an anesthesia machine for mechanical ventilation. Anesthesia maintenance involved continuous intravenous infusion of propofol at a dose of 3 mL/kg. The mean arterial pressure (MAP), heart rate (HR), and blood oxygen saturation (SpO2) were recorded at various time points: before anesthesia injection (T0), after laryngeal mask insertion (T1), 5 min after the operation started (T2), 15 min after the operation started (T3), and before the end of the operation (T4). Additionally, the recovery time was recorded. The blood pressure of patients in the esketamine group exhibited higher levels compared to those in the sufentanil group at multiple time points during the operation, while maintaining a more stable intraoperative blood pressure and shorter postoperative recovery time than that observed in the sufentanil group. The blood pressure and heart rate of patients in the esketamine group exhibited significant fluctuations after laryngeal mask implantation compared to pre-anesthesia induction, with a statistically significant increase observed. Conversely, no significant changes were observed in the sufentanil group. The heart rate and oxygen saturation showed no significant differences between the two groups, nor did the amount of propofol administered during the procedure. The utilization of esketamine during the induction phase of bronchoscopy and lavage under general anesthesia can enhance hemodynamic stability and reduce the occurrence of hypotension, thereby facilitating postoperative anesthetic recovery.

Mesh topology-based spurious pressure stabilization in 3D finite elasticity using Voronoi tessellations

AbstractIn this paper, we present a mesh topology-based stabilization approach to suppress spurious pressure modes in 3D nearly-incompressible finite elasticity. The focus lies on a mixed formulation with lowest-order approximation for the displacement and pressure fields. Motivated by the fact that the popular H1/P0 element does not fulfill the inf-sup condition, all possible local spurious pressure modes are derived on a patch of elements. The nullspace method is used to determine all spurious pressure solutions. From this, the topological requirements of the finite element mesh are established. We conclude that no more than four elements are allowed to intersect in the same vertex to overcome local checkerboarding. To fulfill this requirement, we employ non-degenerate 3D Voronoi diagrams with several different site distributions. These result in random, centroidal, and honeycomb Voronoi meshes. The resulting convex polyhedral elements are discretized by a polyhedral mixed finite element based on the lowest possible interpolation pair. The numerical examples illustrate that spurious pressure modes do not occur for any degree of mesh refinement as long as the topological mesh requirements are met. Furthermore, it is shown that the numerical inf-sup test is passed. By violating the topological requirements, it is shown that a stable pressure field cannot be guaranteed and the checkerboard phenomenon is provoked.

Adaptive control of airway pressure during the expectoration process in a cough assist system.

Existing Mechanical Insufflation-Exsufflation (MI-E) devices often overlook the impact of cough airflow pressure on mucus clearance, particularly lacking in control over airway pressure during the expiratory phase, which can lead to airway collapse and other types of airway damage. This study optimizes the design of cough assist system and explores the effectiveness of PID and adaptive control methods in regulating airway pressure. The adaptive control method compensates for hose pressure drop by online estimation of the ventilatory hose characteristics. It achieves precise tracking of target pressure and ensures the generation of peak flow rates effective for mucus clearance, even in the absence of known patient lung physiological states and unknown hose leakage parameters. Through a series of comparative experiments, this paper confirms the significant advantages of adaptive control in reducing oscillations and overshoot, capable of more stable and precise airway pressure adjustments. This improved control strategy not only enhances clinical safety but also significantly improves therapeutic outcomes and reduces the risk of complications. The findings indicate that the revamped cough assist system, employing an adaptive control strategy, can effectively prevent airway damage during assisted coughing, offering a safer and more effective sputum clearance solution for critically ill patients with expectoration disorders.

Boiling heat transfer of water on smooth and square pin fins surfaces in minichannel

In this investigation, flow boiling heat transfer and hydrodynamic instability using deionized water in a minichannel with smooth and square pin fin surfaces was experimentally examined. The study is aimed to assess local and overall heat transfer coefficients, heat transfer coefficients, pressure drop and Nusselt number across various liquid mass flux ranges (50–93 kg m−2 s−1) and a constant heat flux of 46.91 kW/m2. The minichannel, with a hydraulic diameter of 2.85 mm, features a rectangular shape. Experimental testing was conducted on aluminum surface within a minichannel of dimensions 270 mm in length, 30 mm in width, and 1.5 mm height. The square pin fins are integrated at the base of the boiling surfaces, arranged in staggered form. The results revealed that the boiling heat transfer coefficient on square pin fin surfaces was approximately 88 % higher than that on smooth surfaces. Additionally, a notable increase in local heat transfer coefficient was observed for square pin fin surfaces (i.e., 34.64 kW/m2.K) compared to smooth surfaces (8.09 kW/m2.K) at the same mass flux of 50 kg/m2.s. Besides, the square pin fins surface exhibited a lower and stable pressure drop, particularly near annular flow regimes, compared to the smooth surface. Notably, the highest pressure drop observed was 4.8 kPa for the square pin fins surface, while the smooth surface experienced a higher pressure drop of 6.36 kPa, accompanied by more pronounced pressure fluctuations during annular flow.

Thermodynamic and economic analysis of a novel compressed air energy storage system coupled with solar energy and liquid piston energy storage and release

Compressed air energy storage (CAES) is one of the important means to solve the instability of power generation in renewable energy systems. To further improve the output power of the CAES system and the stability of the double-chamber liquid piston expansion module (LPEM) a new CAES coupled with liquid piston energy storage and release (LPSR-CAES) is proposed. The coupled LPEM conducts suction stage B at the end of the expansion stage, ensuring stable exhaust pressure and temperature for the module. By establishing the thermodynamic and economic models of LPSR-CAES, the effect laws of key node parameters on the system performance are investigated. The results show that the heat transfer between liquid droplets and air dominates the heat transfer in LPEM. The proposed LPEM exhibits excellent isothermal performance and stability, with a maximum temperature difference of about 20 K during the cycle, and stable exhaust temperature changes within 10 K. Under the design conditions, the converted electrical efficiency, round-trip efficiency, exergy efficiency and net present value of the system are 68.31 %, 58.86 %, 66.99 % and 12.25 M$ respectively. The higher the solar supplement temperature, the more outstanding the thermal and economic performance of the system. The short-term energy storage system performance of the proposed system is more prominent. Based on the actual light data, the system can achieve 72.09 % and 69.41 % of converted electrical efficiency and exergy efficiency, respectively, at the 219th day. The results of this study provide theoretical support for the engineering application of the proposed system.

The grouting plugging mechanism of layered jointed rock mass considering the time-varying yield stress of grout

Slurry retention in fractures decreases after grouting is completed and the pressure supply is stopped, which affects the grouting sealing effect and prevents or restrains the occurrence of such adverse conditions. Based on the time-varying yield stress of grout, a theoretical analysis model of grouting diffusion decay is established, the decay height variation function and the minimum pressure stabilisation time calculation formula are derived, and the sealing mechanism of a jointed rock mass with multiple joints is studied. Moreover, a 3D visualisation laboratory test device for grouting diffusion decay of a jointed rock mass with layers was developed to analyse the diffusion and decay process of grout with different water-cement (W/C) ratios visually, and the correctness of the theoretical model was verified. The results show that: (1) the W/C ratio of grout should not be greater than 2, otherwise it is difficult for grout to remain in the cracks; (2) a large fissure opening easily spreads grout but is not conducive to the retention of grout; and (3) the time of stable pressure determines the retention rate of the slurry in the crack. When the horizontal crack opening width is 3 mm and the W/C ratio of the slurry is 1, the minimum stable pressure time to achieve a better sealing effect is 810 s. The research results can be used to reasonably plan the grouting time and improve the grouting efficiency to ensure the grouting effect, which is crucial for improving the theoretical system of grouting technology.

Explore the mechanism of yishenjiangya formula in the treatment of senile hypertension based on multi-omics technology

Ethnopharmacological relevanceThe Yishenjiangya formula (YSJ) is a traditional Chinese medicine (TCM) primarily composed of qi-tonifying components. This classic formula is commonly utilized to treat kidney qi deficiency in elderly patients with hypertension. According to TCM, maintaining a balance between qi and blood is crucial for stable blood pressure. Kidney qi deficiency can disrupt this balance, altering fluid shear force and, ultimately, leading to hypertension, particularly in elderly populations. Despite YSJ's efficacy in treating hypertension, its specific anti-hypertensive mechanisms remain unclear. Aim of the studyYSJ is commonly prescribed for elderly patients with hypertension. Earlier metabolomics studies demonstrated that YSJ exerts antihypertensive effects by influencing four key pathways: linoleic acid metabolism, glycerol phospholipid metabolism, arginine and proline metabolism, and steroid hormone biosynthesis. This study aims to combine metabolomic and proteomic analyses to thoroughly understand the molecular biological mechanisms responsible for YSJ's anti-hypertensive properties. MethodsUltra-Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS) metabolomics, combined with Label-Free Quantitation (LFQ) proteomics, was employed to analyze serum samples from elderly individuals with and without hypertension pre- and post-YSJ intervention. Serum levels of candidate proteins were assessed using enzyme-linked immunosorbent assay, and receiver operating characteristic curves were used to evaluate the diagnostic performance of the target proteins. ResultsEight differentially expressed metabolites and three differentially expressed proteins were identified as potential therapeutic targets of YSJ. These substances are primarily involved in unsaturated fatty acid metabolism, fluid shear stress and atherosclerosis pathway, primary bile acid biosynthesis, proline metabolism, apoptosis, and endoplasmic reticulum stress. YSJ exerts its therapeutic effects on hypertension in the elderly by modulating these pathways. ConclusionsYSJ effectively treats senile hypertension. By analyzing the correlation between therapeutic targets and pathways, YSJ's anti-hypertensive effect was achieved by inhibiting lipid peroxidation and matrix degeneration. Combining metabolomics and proteomics provides an effective method for uncovering YSJ's anti-hypertensive mechanisms.

Research on the generation and modulation of active pressure wave for pipelines leak diagnosis

In this paper, a novel device that uses compressed air to generate pressure waves in the liquid pipeline is proposed. Experimental investigations are carried out to explore the modulation method of the pressure wave generated and the application potential of the device in leak diagnosis. The consequences show that the device can generate safe, stable and controllable pressure waves. The characteristics of produced pressure wave under different excitation frequencies and inflation pressure are investigated with the combination of experiments and theory analysis. The parameters that affect the excitation behaviors of the device are pointed out theoretically. Finally, the performance of the device under continuous excitation and single excitation is tested in the leaking pipe. Through the extraction and analysis of the signal features in the frequency domain, the leakage can be diagnosed and distinguished under both excitation methods.

A rare case of bilateral malignant glaucoma after cataract surgery with capsular tension ring implantation: a case report

BackgroundBilateral malignant glaucoma induced by a capsular tension ring associated with ring-shaped cysts of the ciliary body post-cataract surgery is rare. Herein, we present a case to highlight the possibility of capsular tension ring-induced malignant glaucoma.Case presentationA 59-year-old woman underwent phacoemulsification combined with capsular tension ring implantation for cataracts and zonular fibre laxity in both eyes. Upon admission, annular ciliary masses were detected in both eyes using ultrasound biomicroscopy. Two months post-surgery, the patient experienced vision deterioration, high intraocular pressure, and an axial shallowing anterior chamber in the right eye, and responded poorly to traditional anti-glaucoma medication. Ten days later, similar symptoms appeared in the left eye. Ultrasound biomicroscopy detected contact between the ciliary body and the capsular tension ring. Subsequently, malignant glaucoma was diagnosed. Anterior and posterior capsulotomies performed peripheral to intraocular lens optics using neodymium: YAG laser restored communication and alleviated the symptoms. A one-year follow-up revealed stable intraocular pressure and anterior chamber in both eyes.ConclusionsThis is the first case report of bilateral malignant glaucoma after cataract surgery induced by capsular tension ring, which is associated with bilateral ring-shaped cysts of the ciliary body. Blockage between the ciliary body and capsular tension ring was confirmed using ultrasound biomicroscopy.

A hybrid SPH model of the Navier-Stokes and Boussinesq equations for simulating wave propagation and deformation

A two-way hybrid model based on the smoothed particle hydrodynamics (SPH) method is proposed in this paper to simulate wave propagation and deformation effectively. The hybrid model is composed of two submodels: the first submodel is based on the Boussinesq equations (B-SPH) for simulating wave propagation, and the second submodel is based on the Navier-Stokes (N-S) equations (NS-SPH) for simulating wave deformation caused by interactions with structures. The exchange of information between the two submodels is realized through an open-boundary method: the results derived from the B-SPH submodel are transferred to the open boundaries of the NS-SPH submodel through a relaxation function; the information derived from the NS-SPH submodel is matched to the open boundaries of the B-SPH submodel through the continuity equation. To obtain a stable pressure field in the NS-SPH submodel, the particle shifting technique (PST) is implemented. The subsequent validation of the hybrid model includes four typical numerical examples related to solitary and regular waves. The agreement between the numerical results and the experimental data indicates that the proposed hybrid model is suitable for simulating the propagation and deformation of shallow water waves. Compared with the traditional NS-SPH model, which uses N-S equations to describe the whole fluid domain, the hybrid model has greater computational efficiency.

Evaluation of salt particle collection devices for coastal metal storage facilities with natural ventilation

Abstract Stress corrosion cracking (SCC) is a potential threat to metal containers stored in coastal facilities utilizing natural ventilation due to sea salt particles in the airflow. This study investigates the applicability of low-pressure salt particle collection devices developed by the Central Research Institute of Electric Power Industry (CRIEPI) in Japan (reports N08050 and N11044) to natural ventilation systems in Taiwanese coastal storage facilities. We evaluate the capture efficiency and pressure drop of these devices compared to conventional stainless steel filters. The pressure loss of the collection devices was assessed using the CRIEPI model and compared with a handbook model, demonstrating high agreement. Capture efficiency analysis revealed a reduction rate of approximately 78% for the salt particle collection device. However, peak analysis indicated this reduction was primarily effective for particles exceeding 10.2 μm in diameter. Compared to stainless steel filters, the collection devices offer lower reduction efficiency but with a stable pressure drop and potentially lower maintenance costs. This study also emphasizes the need for optimizing salt particle reduction methods by considering the trade-off between capture efficiency and pressure drop.

Tacrolimus Therapy Among Steroid-Resistant Nephrotic Syndrome Children: A Preliminary Study in West Java, Indonesia

Objective: To explore the outcomes of Tac therapy for Steroid-Resistant Nephrotic Syndrome (SRNS) and its implication in reducing the number of CKD events.Methods: An open, prospective, cohort study was conducted at a tertiary hospital in Bandung, West Java, Indonesia. Children (age 1–18 years old) with steroid and cyclophosphamide resistant nephrotic syndrome were enrolled in this study. Blood pressure, urinary protein, serum ureum, and creatinine levels were measured every month, Tac and soluble urokinase plasminogen activator receptor (supaR) levels were assessed at the 0, third, and sixth months.Results: Ten of fifteen subjects enrolled in this study got better within 3–6 months with a trend of decreasing suPAR level and proteinuria, as well as stable blood pressure and serum creatinine and ureum level. During treatment, no side effects of the subjects were found with the Tac level maintain safely.Conclusion: Tac is an effective and safe agent in treating SRNS, especially for those do not respond well to an alkylating agent.

Flow characteristics and factors affecting flow pulsation of external meshing herringbone gear pump

To enhance the outlet flow stability of the external herringbone gear pump, an analysis was conducted on the main influencing factors, key geometric parameters were identified, and a numerical model was developed for fluid analysis. A numerical model was then established for fluid analysis. The accuracy of the numerical model was verified by comparing it with experimental results, with simulation errors of displacement and volumetric efficiency being &lt; 5%, ensuring the simulation's accuracy. The simulation results indicated that the pump's head (49.7808 m) and outlet pressure (4.9285 bar) remained stable. At 700 rev/min, the simulated volumetric efficiency was 82.94%. Subsequently, the impact of helix angle, changes in center distance, and tip clearance on outlet flow stability were analyzed. The analysis revealed that increasing the helix angle from 27° to 30° could reduce flow pulsation. A slight reduction in center distance from 180.3 (δ = +0.3 mm) to 179.9 mm (δ = −0.1 mm) effectively decreased mass flow difference and outlet pressure pulsation, enhancing outlet output stability. Reducing tip clearance from 0.25 to 0.12 mm, while meeting design requirements, resulted in more stable pressure and lift output. These results ensured smooth pump operation, improved outlet output stability, and met low-flow pulsation requirements. This study offered valuable insights into the design and production of the external meshing herringbone gear pump.

Research on Solid-State Linear Transformer Driver Power Source Driving Atmospheric Pressure Plasma Jet Treatment of Epoxy Resin

The Solid-State Linear Transformer Driver (SSLTD) is a nanosecond pulse power source characterized by its fast rise time and adjustable output waveform. It can generate uniform and stable atmospheric plasma jets, which is suitable for material surface modification. In this study, a 15-stage SSLTD was designed and assembled, which can produce a stable nanosecond pulse voltage up to 15 times the amplitude of the charging voltage at high frequencies, with a rise time of approximately 10 ns. This device can be used to generate stable atmospheric pressure Ar plasma jets with an electron density in the range of 1015~1016 cm−3 and gas temperatures close to room temperature. After the modification treatment by the plasma jets, the content of the C=O groups on the surface of the epoxy resin significantly increased in the wavelength range of 1720~1740 cm−1, and its flashover resistance was noticeably enhanced. The optimal comprehensive modification effect was achieved at a charging voltage of 600 V, pulse width of 50 ns, and pulse frequency in the range of 800~1000 Hz.

Enhancing geothermal efficiency: Experimental evaluation of a high-temperature preformed particle gel for controlling preferential fluid flow

Enhanced Geothermal System (EGS) reservoirs represent a vital frontier in clean energy production. However, short-circulation flow within these reservoirs can significantly affect their immediate efficiency and long-term viability. Injected cold fluids moving through wide fractures or direct channels between injection and production wells reduce thermal production temperatures, disrupting energy output. Preformed Particle Gels (PPGs) have proven effective in controlling preferential fluid flow in oil and gas reservoirs, effectively regulating fluid movement. This work explores the potential of a novel High-Temperature Preformed Particle Gel (HT-PPG), designed for geothermal applications, to plug fractures in a simulated geothermal reservoir. Core flooding experiments in coated and uncoated sandstone models were conducted under varying HT-PPG sizes, swelling ratios, and fracture widths to determine gel plugging efficiency. Variations in the HT-PPG injection pressure, breakthrough pressure, and residual resistance factor (Frr) were evaluated. Water breakthrough pressures can reach 464.10 psi/ft. While the stable injection pressure of HT-PPG decreased with increasing swelling ratio and fracture width, it was higher in uncoated cores. The HT-PPG significantly sealed the fractures, drastically reducing conductivities to millidarcy levels. This work validates HT-PPG a robust solution to mitigate fluid diversion challenges in sandstone EGS reservoirs, enhancing performance and advancing sustainable geothermal energy production.

Two Patients With Ipsilateral Cerebellar Hemorrhage After Superficial Temporal Artery-Middle Cerebral Artery Bypass Grafting.

To summarize the clinical experience of ipsilateral cerebellar hemorrhage after superficial temporal artery-middle cerebral artery bypass surgery. The clinical data of 2 patients with cerebellar hemorrhage after superficial temporal artery-middle cerebral artery bypass grafting were retrospectively collected, including 1 case with left cerebellar hemorrhage after left cerebral artery bypass grafting and 1 case with right cerebellar hemorrhage after right cerebral artery bypass grafting. The perioperative blood pressure, laboratory, and imaging data were analyzed. All patients had a history of hypertension, and their perioperative blood pressure was stable. Low-density lipoprotein cholesterol and high-density lipoprotein cholesterol were normal before the operation. Cerebral magnetic resonance imaging showed cerebral atherosclerosis and multiple ischemic cerebral infarcts. At 24 hours after surgery, the patients' continuous epidural low drainage was 260 mL and 160 mL, respectively. The amount of cerebellar bleeding was small, and no new sequelae were left after conservative treatment with drugs. Cerebellar hemorrhage after superficial temporal artery-middle cerebral artery bypass grafting is related to perioperative blood pressure fluctuation, hemodynamic changes, hemorrhagic transformation of ischemic lesions, and excessive cerebrospinal fluid drainage. Maintaining stable blood pressure during the perioperative period and avoiding excessive and rapid loss of cerebrospinal fluid after operation can reduce the occurrence of this complication.

Simulated analysis and experimental validation of sound field distribution regularity for a large-scale non-anechoic harbor pool

The large-scale underwater space, such as large water pool or large-scale harbor pool can provide a good experimental environment for the measurement of the underwater radiated noise of vessel. However, it's not as simple as measuring the sound power of a small machine in the air, the measurement and evaluation of the low frequency mechanical noise and radiated sound power of vessel requires a specific reverberation environment in the large-scale underwater space. Therefore, in this paper, the reverberant sound field characteristics of large-scale underwater space are simulated and calculated by finite element analysis, and experimental measurements are carried out in the large-scale harbor pool. It was found the cut-off frequency of large-scale underwater space depends on the depth of the water pool, and the lower limit frequency depends on the volume of the water pool. The dock door does not reduce the spatial average sound pressure in the reverberation sound field, the floating box platform does not effect on the cut-off frequency but has an effect on the sound energy of the reverberant sound field. It is possible to select the appropriate underwater experimental environment for the measurement and evaluation of different mechanical noise sources. The sound pressure level obtained by calculating the sound source at different locations in the reverberation area is basically the same, and in a 16 × 22 hydrophone arrays, more than 160 array elements are selected, each between 0.25 m and 1 m, a stable sound pressure level can be obtained through spatial averaging. Through experimental measurement verification in the large-scale harbor pool, low-frequency sound sources are emitted from 6 different positions, three hydrophone arrays data are collected, and the measured sound pressure level error is within 1.4 dB. These conclusions are conducive to the actual measurement and evaluation of noise sources of vessel.