Pistoning is defined as the back-and-forth movement of the catheter at the insertion site. To determine the frequency of pistoning in continuous renal replacement therapy catheters (CRRTC) and its relationship with intravascular thrombosis and catheter dysfunction. A longitudinal descriptive study (March 2023-June 2024) was conducted in two intensive care units. Patients with CRRTC inserted in these units were included.Body mass index (BMI), insertion site, dwell time, and reason for removal were recorded. At each dressing change, pistoning, dysfunction, day of onset, suture fixation status (SFS), hematoma, and line traction were assessed. After catheter removal, ultrasound was performed to determine intravascular thrombosis. Descriptive statistics and bivariate analysis using chi-square or Fisher's exact test and t-Student test were applied, with significance set at p ≤ 0,05. A total of 63 catheters were analysed. Pistoning occurred in 42.9% (n = 27;) and dysfunction in 31.8% (n = 20), at median 3 [P25 = 2-P75 = 9] and 3.5 [P25 = 1.5-P75 = 6.5] days respectively. Intravascular thrombosis was identified in 26.1% (n = 12). Incorrect SFS was observed in 59.3% of catheter with pistoning (CWP) compared with 11.1% of catheter without pistoning(CWoP) (p < 0.001). CWP remained in place for 11 days (8.5) and CWoP for 7.3 days (3.9) (p = 0.02). Patients with dysfunction had a BMI of 34.5 kg/m2 (SD = 10.3) compared with 29.8 kg/m2 (SD = 4.6) in those without dysfunction (p = 0.03). No significant differences were found between pistoning and thrombosis (p = 0.30) or between pistoning and dysfunction (p = 0.06). Pistoning was frequent and was mainly associated with defective SFS and longer dwell time. Obesity was identified as a factor associated with catheter dysfunction. Nearly half of CRRT catheters present pistoning, associated with inadequate fixation and longer dwell time. Catheter dysfunction is more frequent in patients with obesity.
To reduce operator-dependent variability and improve surgical precision, robot-assisted piston prosthesis placement and crimping during otosclerosis surgery may represent a promising approach. However, dedicated microsurgical forceps for this application are not yet available in clinical practice. This study aimed to assess the feasibility and precision of piston prosthesis placement and crimping, comparing manual and robot-assisted techniques. A 3D-printed temporal bone model was modified to measure forces applied to the incus. Robot-assisted manipulation was performed using a robotic arm coupled with custom-designed microforceps. Five otologists performed two tasks (piston placement and crimping) under three conditions: (1) manual under visual control, (2) robot-assisted, both applied to placement and crimping, and (3) manual without visual feedback, applied to crimping only. This resulted in five procedures, each repeated three times (n = 15). Maximal force (N) and torque (N.mm) were recorded and compared using Mann-Whitney and Kruskal-Wallis tests. Robot-assisted piston placement resulted in lower maximal torque compared with the manual technique (4.2 ± 3.96 vs. 7.5 ± 4.73 N.mm, p = 0.037), with no difference in maximal force. During crimping, robot-assisted manipulation generated lower maximal force (0.15 ± 0.09 vs. 0.27 ± 0.09 N, p = 0.0126) and lower maximal torque (6.1 ± 3.41 vs. 11.5 ± 3.09 N.mm, p = 0.004) than manual crimping. No difference was observed between manual crimping performed with and without visual control. Procedure duration was longer with robot-assisted manipulation for both placement and crimping (all p < 0.0001). Robot-assisted piston prosthesis placement and crimping were feasible and were associated with reduced mechanical loads applied to the incus. 5.
The standard meter water flow prover is widely used due to its mature technology and high work efficiency. However, the process of sending the standard meter for calibration is not only time-consuming and laborious but also introduces deviations due to differences in installation and operating conditions. Therefore, by leveraging the high precision, convenient adjustment, and simple traceability of the piston prover, as well as the good repeatability of the standard meter, this paper proposed a cyclic self-calibration method, which iteratively transmits the calibrated piston value to different flow points of the standard meter through the standard meter itself and the transition flow meter, so as to realize the in situ transmission of the value from the high-precision piston to the wide range of standard meter. The water flow standard device and the cyclic self-calibration method, combining the standard meter and the transfer meter in series and parallel, were introduced; the uncertainty transfer chain was analyzed based on the error transfer theory; and experimental validation was conducted. The results show that the proposed self-calibration method is feasible, that the (0.005~4) m3/h high-precision flow rate of the piston can be extended to the (4~1250) m3/h of standard meters through multiple self-calibration value transfers, and that the expanded uncertainty of the water flow standard device is better than 0.20% (k = 2).
This study presents an integrated experimental-numerical approach for evaluating the wear behavior of three non-standardized hypereutectic aluminum-silicon (Al-Si) piston alloys based on the AlSi25CuCr system, namely AlSi25Cu4Cr (M1), AlSi25Cu5Cr (M3), and AlSi25Cu5Cr (M5). The wear coefficient was determined experimentally under boundary-lubrication conditions, while the contact conditions in the piston-cylinder system were evaluated using Finite Element Analysis (FEA) and implemented within the Archard wear model. The results reveal a pronounced inconsistency between hardness and wear resistance. Although hardness increases from 1363 MPa (M1) to 1677 MPa (M5), the corresponding wear depth increases from 13.94 nm to 27.61 nm per engine cycle. This behavior is attributed to differences in microstructural characteristics, particularly the morphology and distribution of silicon particles and intermetallic phases, which significantly influence the tribological performance of hypereutectic Al-Si alloys. The experimentally determined wear coefficient K also shows a significant increase, rising from 12.14 × 10-5 (M1) to 29.59 × 10-5 (M5). The lowest wear is observed for alloy M1, whereas M5 exhibits the poorest tribological performance. These findings demonstrate that microstructural characteristics, particularly the morphology and distribution of silicon particles and intermetallic phases, have a dominant influence over hardness in governing wear behavior. The main scientific contribution lies in the direct coupling of experimentally determined material properties with realistically simulated contact conditions, enabling a quantitative and physically consistent comparison of piston alloys under identical operating regimes. The proposed methodology provides a reliable framework for material selection and optimization of piston alloys with enhanced wear resistance.
This article presents a dataset generated from a cylindrical plunge grinding process conducted in an industrial piston ring manufacturing environment. The data aim to support studies focused on process capability, variability, robustness, parameter optimization, and modelling approaches in grinding research. The experimental conditions were defined following a Central Composite Design for k = 4 factors and axial distance ρ=1.5, which established the levels of Wheel infeed rate, Dressing speed, Grinding wheel peripheral speed, and Dressing depth. These parameter combinations were carried out on the shop floor under real production constraints, ensuring that the collected measurements represent industrial operating conditions rather than laboratory simulations. Two external noise factors were considered during data collection, consisting of the different mandrels and the position of the piston ring within the production package. These noise sources reflect variations commonly encountered in manufacturing and allow researchers to investigate the robustness and sensitivity of dimensional responses. A CCD with thirty runs, being sixteen factorial points, eight axial points, and six center points, organized in two blocks of experiments, was performed, associated with four noise combinations, defined according to an experimental plan. For every condition, ten repeated measurements, represented by ten piston rings sampled from the package and assembled in different mandrels, were acquired using the dimensional control fixture routinely employed in the industry, forming a dataset of 1200 runs. This procedure ensured consistency with existing quality inspection practices and provided a rich structure suitable for repeatability and uncertainty analyses. The dataset includes raw measurements, process parameters, and experimental identifiers that enable multilevel exploration of machining performance. Its structure supports diverse analytical applications, including modelling of process capability, variability, evaluation of noise effects, optimization of input parameters, statistical analysis of repeated measures, and the development or validation of data-driven and machine learning methods. Owing to its industrial origin, the dataset offers realistic variability patterns and is relevant for comparative studies, benchmarking activities, and the development of predictive or robust design frameworks in manufacturing research.
Driven by the demands for high power density and low energy consumption, optimizing the lubrication system of opposed-piston two-stroke (OP2S) diesel engines is crucial for enhancing efficiency and reliability. This paper proposes a lubrication system design method based on multi-bearing, multi-objective collaborative optimization. By combining the AMESim simulation platform and the HEEDS optimization algorithm, the minimum oil film thickness and oil consumption are optimized under three typical operating conditions (800, 1800, and 2800 r/min). The results show that the optimized circulating flow rate is reduced by 6% under all operating conditions. The opti-mized scheme effectively improves the efficiency of the lubrication system under various operating conditions, with significant optimization effects at high speeds. This optimization method solves the single-objective optimization and over-lubrication problems existing in traditional design methods, providing guidance for practical applications.
We have developed an alternating current (AC) calorimetry method using a piston-cylinder apparatus for measuring heat capacity and thermal conductivity under high pressures up to 2.1 GPa and at low temperatures down to ∼40 K. This new AC calorimetry is based on a planar one-dimensional heat conduction model employing a pair of platinum resistors, enabling the measurement of thermal properties in liquid samples-an application that was not straightforward with conventional AC calorimetry. We demonstrate the effectiveness of this method through its application to NH4Cl, cyclohexene, methylcyclohexane, and ice.
This paper examines how radiating surface structure can influence the properties of beam-shaping of the piezoelectric piston type underwater acoustic transducers. The study is done using a broad theoretical, numerical and experimental method. This study presents a comprehensive analysis of the far-field radiation characteristics of circular, square, hexagonal, and octagonal piston-type ultrasonic transducers for underwater applications. The models were validated with three-dimensional finite element simulations and experimental measurements using a wafer Tonpilz transducer prototype. This analysis demonstrates that piston geometry has no significant effect on radiation characteristics for small apertures whose Equivalent Circular Diameter (ECD) is less than half the wavelength. The circular piston is found to exhibit superior performance at increased apertures. Result shows that circular pistons provide superior beam uniformity, narrow main lobes, and low side-lobe levels, making them highly efficient for focused energy transmission, sonar, and underwater communication systems. Experimental validation is provided only for the circular case, while theoretical and numerical results are presented for all pistons. This control of the beam makes the circular piston the solution to accurate acoustic control. Finite element analysis and experimental measurements on a circular wafer transducer proved the validity of the theoretical models. This high level of agreement validates that the findings can directly applied to designing advanced underwater acoustic arrays.
Objective: To investigate the clinical classification and surgical outcomes of congenital middle ear malformations accompanied by facial nerve anomalies. Methods: A retrospective cohort study was conducted to analyze clinical data of patients with congenital middle ear malformations and concomitant facial nerve anomalies who received treatment in the Department of Otolaryngology, Zhujiang Hospital, Southern Medical University, between January 2021 and December 2024. Facial nerve anomalies were categorized into four distinct types: partial obstruction of the oval window, complete obstruction of the oval window, aberrant course over the promontory, and branching anomalies. Ossicular chain malformations were classified in accordance with the Teunissen classification system. Individualized hearing reconstruction strategies were implemented based on the specific anatomical characteristics of the anomalies. All patients were followed up for 3 to 24 months. Postoperative therapeutic efficacy was evaluated by comparing preoperative and postoperative mean air conduction thresholds and air-bone gaps (ABG), while monitoring surgical complications. Results: Thirteen patients (17 ears) aged [M (Q1, Q3)] 15.0 (11.5, 21.0) years were included, with eight males and five females. Facial nerve anomalies were categorized as follows: partial obstruction of the oval window in six ears (three cases of Type Ⅰ, three cases of Type Ⅲ), complete obstruction of the oval window in three ears (one case of Type Ⅰ, two cases of Type Ⅲ), aberrant course over the promontory in six ears (all Type Ⅳ), and branching anomalies in two ears (both Type Ⅳ). Hearing reconstruction modalities employed included: incus-stapedial piston placement following vestibular fenestration in nine ears, malleus-stapedial piston placement following vestibular fenestration in two ears, partial ossicular replacement prosthesis (PORP) implantation in three ears, total ossicular replacement prosthesis (TORP) implantation in one ear, stapes mobilization in one ear, and laser-assisted ossicular chain release in one ear.Statistical analysis revealed that postoperative mean air conduction thresholds [(33.8±15.2) dB HL vs (60.1±13.8) dB HL, P<0.001] and mean ABG [(14.6±6.9) dB vs (37.2±9.2) dB, P<0.001] were significantly reduced compared with preoperative values. Postoperative ABG≤20 dB was achieved in 15 ears (88.2%). Postoperative complications were limited to transient vertigo in five cases and taste disturbance in two cases. No cases of facial paralysis, sensorineural hearing loss, tympanic membrane perforation, or tinnitus were observed. The median follow-up duration was 6.0 (5.5, 20.0) months. Conclusion: Individualized hearing reconstruction strategies based on the classification of facial nerve and ossicular chain anomalies can effectively protect the facial nerve and achieve significant hearing improvement, demonstrating favorable clinical outcomes. 目的： 探讨先天性中耳畸形伴面神经畸形的临床分类及手术疗效。 方法： 回顾性分析2021年1月至2024年12月于南方医科大学珠江医院耳鼻咽喉头颈外科行手术治疗的先天性中耳畸形伴面神经畸形患者临床资料，将面神经畸形分为：部分遮窗、完全遮窗、走行鼓岬表面及分支畸形四类，听骨链畸形根据Teunissen分型，按不同策略重建听力，术后随访3~24个月，比较手术前后气导平均阈值、气骨导差（ABG）变化，观察手术并发症，从而评估手术疗效。 结果： 纳入13例（17耳）患者，男8例，女5例，年龄［M（Q1，Q3）］15.0（11.5，21.0）岁。面神经部分遮窗6耳（Ⅰ型3耳、Ⅲ型3耳），完全遮窗3耳（Ⅰ型1耳、Ⅲ型2耳），走行鼓岬表面6耳（Ⅳ型6耳），分支畸形2耳（Ⅳ型2耳）。9耳前庭开窗Piston连接砧骨，2耳前庭开窗Piston连接锤骨，3耳部分听骨赝复物（PORP），1耳全听骨赝复物（TORP），1耳镫骨撼动术，1耳激光听骨链松解术。与术前相比，术后气导平均听阈［（33.8±15.2）分贝听力级（dB HL）比（60.1±13.8）dB HL，P<0.001］和ABG［（14.6±6.9）dB比（37.2±9.2）dB，P<0.001］均降低。15耳（88.2%）术后ABG≤20 dB。术后5例出现短暂眩晕，2例出现味觉异常。随访时间6.0（5.5，20.0）个月，所有患者无面瘫、感音神经性耳聋、鼓膜破损、耳鸣并发症。 结论： 先天性中耳畸形伴面神经畸形根据面神经畸形和听骨链畸形分类采取不同听力重建策略，可有效保护面神经，显著改善听力，具有良好的临床疗效。.
Objectives: The aim of this study was to determine differences in injury types and frequencies between piston-based and band-based automated chest compression devices in patients with non-traumatic out-of-hospital cardiac arrest (OHCA) at a German cardiac arrest center. Methods: This retrospective single-center study assessed resuscitation-related injuries in OHCA patients using protocol-based early whole-body CT scans at hospital admission. CT scans were reviewed independently by two reviewers blinded to the compression device used. Between May 2015 and September 2021, all patients resuscitated from non-traumatic OHCA, treated with a mechanical chest compression device, and showing stable return of spontaneous circulation (ROSC) until CT examination according to the institutional standard operating procedure for all OHCA patients were included. Patients were categorized by compression device type, and group differences were analyzed using the Chi-square test and Mann-Whitney U test. In addition, patient-level incidences of rib fracture types were calculated, and risk ratios with corresponding 95% confidence intervals were used to compare rib fracture patterns between groups. A p-value of <0.05 was considered statistically significant. Results: Among 71 patients, 32 received band-based and 39 piston-based treatment. Both groups were comparable in resuscitation duration, body constitution, and gender ratio, although the band-based group was older. Thoracic injuries predominated, with rib fractures representing the most frequent injury pattern (64/71, 90.1%). The median number of rib fractures per patient was 10 (IQR 8-12) in the band-based group and 9 (IQR 7-12) in the piston-based group. The band-based group had significantly more liver lacerations (5/32, 15.6% vs. 0/39, 0%; p = 0.01) and displaced rib fractures (117 vs. 87; p = 0.046; patient-level RR = 1.43, 95% CI 1.06-1.93). Conclusions: In this observational study of a CT-based cohort of OHCA patients with stable ROSC, the band-based device was associated with significantly higher frequencies of liver lacerations and displaced rib fractures than the piston-based device. These findings should be interpreted as hypothesis-generating and may support further evaluation of device-specific injury profiles in future studies.
Ground-based telescopes are susceptible to seeing, an atmospheric blur that reduces the resolving power of large observatories to only a few arcseconds. Compensating these effects is critical to realizing the potential of both existing and upcoming extremely large telescopes, a challenging task that requires precise wavefront control. Ultimately, this precision is limited by the wavefront sensor (WFS) design and its inherent capacity to accurately encode phase and amplitude aberrations. In this work, we employ statistical estimation theory to derive fundamental limits to phase and amplitude reconstruction, providing a closed-form expression for the minimum-achievable residual error. For circular apertures, we find that this bound can be saturated by an instrument we refer to as the piston-adapted WFS (PAWS). The PAWS uses a Zernike mode sorter built from spatially varying half-waveplates to isolate the Zernike piston mode, apply a controllable phase shift to it, and then reconstitute the pupil as a pair of irradiance patterns that are nearly linear in incident aberrations. For arbitrary apertures, one can use a single-mode converter to reshape the pupil's native piston mode into Zernike piston and apply the same procedure. We expect our results to improve the residual wavefront errors in future closed-loop adaptive optics systems, while simultaneously finding applications in free-space communication and microscopy.
Mitigating the impact of pointing jitter is a prerequisite for achieving high-precision Dispersed Fringe Sensing (DFS) in dynamic environments. This Letter proposes a tilt-robust phase decoupled reconstruction (PDR) method that utilizes the strict vanishing of tip/tilt-induced phase modulation at the spatial carrier-frequency peak. Leveraging this property, the PDR method extracts the tilt-immune piston phase at the carrier peak and employs multi-wavelength least-squares unwrapping to retrieve the absolute piston error. Both numerical simulations and experiments confirm the method's excellent tilt robustness. Specifically, an experimental piston retrieval precision of 0.034 μm RMS is achieved under continuous sinusoidal pointing jitter, demonstrating the method's capability for high-precision co-phasing in future synthetic aperture telescopes.
Down the hole (DTH) air hammer is widely used in hard rock drilling for its high drill rate. Revealing the influence mechanism of drilling parameters by RC-DTH air hammer is of great significance to promote the application of RC-DTH air hammer impact rotary rock breaking technology in deep hard rock drilling. In this paper, based on LS-DYNA and Smoothed Particle Hydrodynamics, a three-dimensional numerical simulation model of piston-bit-rock in the RC-DTH air hammer impact rotary drilling is established to explore the propagation and action law of stress wave in rock and drilling tools, and to analyze the influence of different drilling parameters on the rock fragmentation effect. A testing facility, known as the RC-DTH air hammer impact energy test platform, has been constructed to confirm the accuracy of the numerical simulation results obtained. After a thorough analysis that accounts for the effects of stress concentration and drilling parameters on the efficiency of rock breaking, the identified optimal operating parameters are as follows: a drilling pressure of 4000 Newtons, a piston impact velocity ranging from 9 to 11 m per second, and a drill bit rotation speed of 30 rpm. Field tests confirmed that applying this optimal parameter set increased the single-impact energy of the hammer by approximately 32.5%, and optimized the energy transfer efficiency to around 17.5%, thereby achieving a quantifiable engineering balance between improving rock-breaking efficiency and reducing tool wear.
The transition from lipid flat disks to vesicles under shock waves is essential for producing nanosized vesicles during sonication. We perform non-equilibrium molecular dynamics simulations to examine how shock waves interact with a lipid flat disk. The lipid disk consists of coarse-grained saturated phospholipid models and is approximately 30 nm in diameter in the gel phase. Shock waves are simulated using a piston-driven method, with piston speeds limited to 1.0 km s-1 or less. When a planar shock wave strikes, the disk's structural changes depend on the impact angle and the shock intensity. A disk with its rotation axis parallel to the shock direction decreases in thickness while maintaining its circular shape. In contrast, a disk with its rotation axis perpendicular to the shock wave direction undergoes radial compression in the shock propagation direction, causing a temporary increase in ellipticity. Behind the shock front, lipid molecules become disordered, as indicated by a reduction in the average P2 order parameter of lipid chains and the gel fraction in the disk. This suggests that shock waves can trigger the phase transition of lipid disks from the gel to the liquid phase. The shock's intensity and the resulting structural changes influence subsequent vesicle formation. During recovery, vesicles often form from the disk after exposure to higher-intensity shock waves or after a temporary anisotropic disk induced by a side impact. This highlights the importance of impact angle. These structural changes in lipid flat disks caused by shock waves may help in understanding and controlling vesicle sizes through sonication.
Coordinated movement along the body axis is critical to locomotion. In segmented, limbless animals, anterior (head) and posterior (tail) segments play different roles in locomotion, leading to a need for flexible coordination across body regions. Larval Drosophila melanogaster present a tractable experimental model for limbless, segmented crawling given the extensive genetic tools available and the optical clarity of the body. Prior work has suggested that, during crawling, all larval body segments contract similarly, despite the fact that each crawl cycle comprises two overlapping phases: a piston involving the most posterior segments and a peristaltic wave involving all body segments. To test whether coordination varies regionally during locomotion, we expressed GCaMP in body wall muscles of larvae of either sex and recorded segmental contraction kinematics and muscle recruitment during many cycles of locomotion in linear channels. Facilitated by machine vision techniques, we discovered new features of larval crawling at multiple scales. First, the propagation of both contraction and recruitment waves slowed approaching mid-body segments, then sped up toward the head. Second, the timing relationship between contraction and recruitment waves could be highly variable in anterior segments. Third, contraction durations showed particularly strong intersegmental correlations among posterior segments. These data suggest posterior segments coordinate to power the piston phase, while anterior segments tolerate greater flexibility to enable reorienting behaviors. Our results depict an unanticipated degree of axial heterogeneity in the coordination of limbless crawling, opening new avenues to study the origins of whole-body coordination and the consequences of segmental diversity for locomotion.
Dry needling (DN) is an effective treatment for cervical pain, but its invasive nature carries risks of adverse events like spinal canal perforation. This study aimed to determine whether cervical spine positioning influences the risk of inadvertent spinal canal perforation during a deep mid-cervical DN technique. Using a flexible human cadaver model, an experienced physical therapist performed 20 pragmatic needle insertions (0.30 mm × 60 mm) targeting the C5 lamina, with 10 attempts executed in a neutral position and 10 attempts in 10 degrees of relative extension. A clinical pistoning maneuver was performed, and final needle placement was independently verified via ultrasound. Spinal canal perforation occurred in 20% of attempts (2 out of 10) in the neutral position when the initial firm end feel was lost during pistoning, leading to full needle advancement. Zero perforations occurred in the extension condition. A significant difference in needle depth was identified between the perforation and non-perforation groups (p = .02). These findings indicate that placing the cervical spine in relative extension may reduce anatomical surface area and minimize the risk of spinal canal perforation.
With the vigorous development of subway systems, particulate matter (PM) and CO2 in subway stations is raising increasing concerns. Here, the characterization of PM and CO2 at seven subway stations with different forms of platform doors in China are studied. The results show that PM concentrations at platforms are higher than those at halls, followed by the outside. CO2 concentrations at platforms are remarkably correlated linearly with passenger number. Subsequently, impacts of piston effect on PM and CO2 concentrations at platforms are assessed. The maximum PM2.5 and PM10 concentrations with half-height platform bailout doors (HPBD) are increased by 20 % and 36 % respectively when the train enters the station, which are higher than those with platform screen doors (PSD). CO2 concentrations are decreased by 1.8 % and 4.6 % under the influence of piston effect at platforms with PSD and HPBD, respectively. Compared with coarse particles (larger than 2.5 µm and <10 µm), fine particles (PM2.5) account for larger mass fraction in total particles (38.22 %-62.57 % at all stations), especially at platforms with PSD. The composition and source apportionment of PM2.5 reveal that Fe is the most abundant element and six pollution sources are identified at all stations. Among them, the indoor source contributes the most to PM2.5 at the station with HPBD. Regardless of the form of platform doors, wheel-rail wear is the largest source of PM2.5 inside each station. The above results are expected to provide reference for the PM control to achieve a healthier underground environment.
The linear range extender (LRE) features a special crankless engine and linear oscillation, which cannot achieve engine starting by accumulating the energy of the starting motor through the flywheel like traditional engines. This paper proposes a self-excited compression method using mechanical resonance mechanism to accumulate energy and enlarge piston reciprocating for starting of the LRE, and a mathematical model considering the coupling of thermodynamics, friction, heat transfer, electromagnetic force, and dynamics in the resonance process is proposed to describe the starting compression behavior, meanwhile the corresponding resonance compression experiment of the LRE is also conducted to verify the effectiveness of the resonance method and model. The results indicate that: this method effectively solves the compression problem of the LRE starting by inducing resonance through precise electromagnetic thrust phase synchronization control and thrust boundary optimization. It enables the LRE to increase the amplitude and reciprocating frequency of piston motion, thereby increasing the energy of compressed gas in the cylinder for fuel ignition. The greater the excitation force, the larger the amplitude of reciprocating and the compression ratio of the engine, the higher the peak gas pressure, and the shorter the resonance cycle period, thereby shortening the starting compression time and facilitating rapid engine compression starting.
Background: Noninvasive transdermal insulin delivery using ultrasound technology has gained attention for improving the glycemic control of insulin-dependent patients. Methods: Indirect functional comparison and evaluation of insulin dosage, between noninvasive ultrasound-mediated transdermal delivery and needle injection methods, was achieved utilizing in vivo blood glucose measurements of temporary hyperglycemic rabbits. Nine rabbits were divided into three groups: (i) untreated control, (ii) subcutaneous injection and (iii) ultrasound-mediated transdermal delivery. Animals were anesthetized using a combination of ketamine hydrochloride and sodium xylazine to produce temporary hyperglycemic rabbits during the experiments. The rabbits in the control group did not receive insulin, while the animals in the ultrasound group received insulin transdermally for 10 min utilizing a customized single-element piston-shaped ultrasound transducer operated by multi-frequency electrical signals from 100 to 200 kHz. Rabbits in the direct subcutaneous injection group were anesthetized and injected with 0.25 units/kg of insulin. Results: With an initial blood glucose baseline level of 228.7 ± 13.1 (mg/dL) for all rabbits, the in vivo results of control group showed an increase above the baseline by 129.7 ± 27.3 (mg/dL) at the end of the in vivo experimental period (80 min). However, the ultrasound-mediated delivery and subcutaneous injection groups showed noticeable statistically significant percentage reductions in blood glucose levels by 43.9 ± 5.4 and 42.7 ± 6.6, respectively, compared to the control group by the end of the in vivo experiments. Conclusions: In vivo glucose response results confirmed that piston-shaped ultrasound transducers achieved indirectly similar insulin dosage delivery by ultrasound energy for tested animals with no statistically significant differences once compared to the results of the subcutaneous needle injection group.
We have developed a time-resolved Compton-scattering imaging technique for visualizing gas behaviours in operating internal combustion engines. This technique employs a digital processing system to record both the pulse height and the timing of detected X-rays, enabling the derivation of Compton-scattered X-ray spectra for each crank angle, which corresponds to the piston position. The observed crank-angle dependency of Compton-scattered X-ray intensity allowed us to successfully capture the density changes of the gas in the combustion chamber associated with piston motion and combustion. In addition, the capability of temperature estimation is discussed with a combination of X-ray Compton-scattering experiments and pressure measurements. This study demonstrates that time-resolved Compton-scattering imaging is a powerful and unique technique for characterizing gas behaviours in an operating internal combustion engine.