j. zhang

Due to the installation space constraints in practical applications, centrifugal compressors often utilize bent intake pipes. Quantifying the correlation between the centrifugal compressor’s operating performance and the flow dynamics within curved inlet tubes is essential. In this research, the accuracy of the numerical methodology was validated using the experimental outcomes. Subsequently, the centrifugal compressor’s performance was simulated for two intake curved ducts, i.e., Pc with a coplanar central axis and Pnc with a non-coplanar central axis, followed by the analysis of the flow characteristics for each intake configuration. The results indicated that Pc produced a symmetrical swirling flow field at the outlet, which was characterized by a lower plane superimposed distortion intensity (PSDI), while Pnc generated an asymmetrical offset swirling flow field with a higher PSDI. The PSDI increased with the flow rate, reaching maximum values of 0.137 for Pc and 0.386 for Pnc. Compared to the inlet straight tube, the performances of the centrifugal compressor connected to Pc and Pnc both decreased, while Pnc exhibited a more significant performance deterioration degree. Under high-speed conditions, the maximum degradation degrees of pressure ratio for Pc and Pnc reached approximately 5.7% and 9.8%, respectively, while the efficiency reduction degree reached approximately 5.3% and 8.7%, respectively. The performance reduction degree for both bent pipes increased with the rising PSDI, exhibiting an exponential correlation. The flow characteristics of the intake pipelines affected the flow behavior within the impeller, with the flow field variation locations closely resembling the distorted regions of the bent pipes.

This study proposes a novel approach to enhance the cavitation performance of centrifugal pumps with low specific speed by incorporating small blades within the impeller flow channel. These blades are deflected at specific angles at their trailing edges to suppress cavitation and improve pump efficiency. Experimental tests were conducted to assess the external characteristics and cavitation performance of a prototype pump, and the results were compared with numerical simulations. The findings indicate that the addition of small blades has minimal impact on the pump's external characteristics but significantly enhances its cavitation performance. Specifically, the low-pressure regions and areas of high-intensity turbulent kinetic energy within the impeller were reduced. Consequently, the volume of cavitation bubbles and the amplitude of pressure pulsation decreased. Flow field analysis revealed that the modified flow structure is more stable, with reduced vortex intensity. The small blades effectively align disordered turbulent flow lines, thereby suppressing cavitation development.

Investigating the aerodynamic characteristics of an ultrahigh-speed elevator between the car and counterweight during the staggering process is crucial for the development of drag reduction and noise abatement technologies. In this study, an actual operating ultrahigh-speed elevator is selected as the research object, and an unsteady flow numerical simulation model for three-dimensional, has been constructed using the method of dynamic mesh. The aerodynamic behaviours of the elevator at various interleaving operating speeds are analysed. The impacts of the counterweight on the flow velocity, pressure, lateral force, aerodynamic drag, and sound pressure level (SPL) of the car are investigated. The results show that a streamlined counterweight can stabilize airflow between the windward areas of the car and counterweight, reducing turbulence, the lateral lift, surface pressure gradients, and SPL, while also lessening the effects of reduced car-counterweight spacing. At a speed of 6 m/s, a bi-arc counterweight with a radius of 250 mm demonstrates superior performance in reducing lateral lift force and aerodynamic drag compared to a traditional rectangular counterweight, with reductions of 12.2% in lateral lift force and 9.3% in aerodynamic drag. Additionally, the simulation and test errors are within 10%, confirming the accuracy of the numerical calculation method.

In this study, a numerical simulation of the static leakage of a subway vehicle was conducted, based on the turbulence model of k-ω Shear Stress Transport (SST). The impact of the leak hole thickness and of the slenderness ratio, on the airtightness of the vehicle is analyzed with a single leak hole, as is the influence of the number, location, slenderness ratio, and area ratio of leak holes, on the airtightness of a train with multiple leak holes. The relative errors of the numerical simulation results are smallest when the leak hole slenderness ratio is 1:16. The relative errors in cases of a single leak hole, and of multiple leak holes are 4.93% and 3.68%, respectively. The pressure relief time first decreases, and then increases as the thickness of the leak hole increases, and is the smallest when the leak is 200 mm in thickness. Keeping the total area of leak holes unchanged, the location and number of leak holes have little impact on the pressure relief time. When door and window leak holes have different thicknesses, changing the area ratio of the door and window leak holes increases the pressure relief time, by a maximum of 1.23 seconds.

For square and circular finite wall-mounted cylinders (FWMCs) with an aspect ratio exceeding 10, the vortex shedding near the tip area leads to the generation of multiple tonal noises. The quantitative analysis of the spanwise distributions of the vortex modal energy with different frequencies was quite limited. This study employs dynamic mode decomposition to decompose the wake of FWMC into distinct frequencies to evaluate the modal energy distribution of pressure fluctuations at each frequency along the spanwise direction. Large eddy simulation combined with the Ffowcs Williams–Hawkings (FW–H) acoustics analogy is applied to a square and a circular FWMC with aspect ratio of 13.6 at a Reynolds number of 2.3 × 104. Two indicators to describe the spanwise energy contribution are proposed. The results reveal that, for square FWMC, the primary modal energy corresponding to Strouhal number ( St ) equal to 0.14 is concentrated below 30% of the cylinder height  owing to the 3D effect. A transition mode of  St ≈ 0.12 is identified in the midspan (0.3 L–0.7L ) without significant contribution to far-field noise spectrum. For circular FWMC, the modal energy is distributed over several frequencies, vortices cells corresponding to the main noise band (0.2 <St< 0.23) are distributed below 0.7 , and the vortices cells in the noise band of 0.15 <St < 0.19 distributed from the midspan to the upper part in a dispersed manner. The noise band with   St≈ 0.08 corresponds to tip-associated vortices gathering above 0.8 .

The high-speed movement of trains generates train-induced wind, commonly referred to as slipstream, which presents a specific safety concern for passengers and personnel. Yet, the fastening system employed to secure ballastless tracks, characterised by its complex shape, substantial quantity, and dense arrangement, remains inadequately investigated regarding its influence on train aerodynamics. In the present study, a sliding mesh technique was employed to comparatively examine the impact of different track configurations—trackless, track-only, and track with a fastening system—on the aerodynamic characteristics, slipstream formation, and wake turbulence induced by trains. The results indicate that the tracks and the fastening system increased the drag force coefficient by 0.73% and 2.05%, respectively, compared with no track. Additionally, tracks and the fastening system had a significant impact on the slipstream velocity near the train and ground. Tracks notably altered the shape of the wake near the ground, and the fastening system exacerbated this phenomenon. Further, the fastening system further intensified the generation of secondary vortices at track and footstep locations.

The aerodynamic performance of axial compressor rotors is negatively affected by the ingestion of boundary layer fluids upstream. As the boundary layer becomes thicker, the blade tip load increases and the local loss is aggravated, especially under off-design operating conditions. The major objective of this research is to evaluate the potential for novel blade sweep designs that can tolerate the ingested low-momentum boundary layer fluids. An optimization design approach using a surrogate model and genetic algorithm is employed. By altering the blade stacking line, the optimized sweep design is obtained. The flow mechanisms that enable the performance of the compressor rotor to be improved are fully analyzed, and the findings indicate that the aerodynamic advantages primarily stem from two key aspects. First, in the tip region, the blade loads are decreased at various chordwise locations and the interaction of the tip leakage flow with the mainstream is alleviated. As a result, the loss near the tip is reduced. Second, the blade sweep design alters the distribution of shock intensity across the spanwise direction, leading to a decrease in shock wave intensity in the mid-span region. This is beneficial in reducing the shock wave/boundary layer interaction strength at the trailing edge of the blade airfoil. Overall, after the sweep design has been optimized to ingest the upstream boundary layer, the compressor rotor experiences a 0.8% improvement in adiabatic efficiency compared with the baseline rotor, while preserving the total pressure ratio and stall margin. Additionally, the redesigned compressor retains the overall performance level under clean inlet conditions. This research provides a potentially effective blade sweep optimization design strategy that allows transonic compressor rotors to tolerate low-momentum upstream boundary layer incoming flows.

Rotating cavitation water jet technology is widely used in many industrial fields such as pipeline cleaning, unblocking, cutting, etc. To more accurately analyse the flow characteristics of rotating cavitating water jets, the specific impact of the nozzle rotational velocity on the evolution of the whole flow field was systematically explored in this work. More specifically, a numerical simulation study of a three-nozzle rotating cavitation nozzle was carried out using the Large Eddy Simulation method of the WALE sub-lattice model. After determining 12MPa as the inlet pressure condition. The tangential velocity, vorticity, cavitation cloud development patterns, and wall pressure changes in the internal flow field at different rotational speeds were compared. From our analysis, it was demonstrated that as the nozzle rotates faster, the tangential velocity of the jet increases, leading to a deflection of the jet. The degree of deflection is positively related to the rotational speed. Under the action of shear, the vortex structure will gradually increase in size as the jet develops and finally breaks up and disintegrates. The period of cavitation cloud development and maximum volume fraction increases with increasing the rotational speed; When the rotational speed increases, the striking pressure of the rotating jet on the wall first increases and then decreases. The fitted jet curve can better reproduce the jet development pattern. The derived fitting formula allows the determination of the corresponding impact angle according to the magnitude of the rotational velocity. The existence of a higher nozzle rotation speed induces a greater curvature of the fitted curve, the deflection angle, and the impact angle. Our work provides a robust theoretical reference for the field application of the rotating nozzle cavitation water jet technology and can be used as technical support for industrial well-bore unblocking and pipeline descaling.

To assess the efficacy of various acupuncture therapies for treating radiotherapy-induced radiation enteritis (RE). Relevant studies on RE treatment through acupuncture and moxibustion were collected from medical databases. These studies were meticulously screened based on stringent inclusion and exclusion criteria. Their methodological quality was evaluated, and data were meta-analysed using Revman 5.3 software. Six studies were included in this analysis. The fixed effect (FE) model revealed a statistically significant difference in the distribution of apparent efficacy between the experimental and control groups [OR = -0.18, 95% CI (-0.25, -0.11), P < 0.00001], as well as in the distribution of cure rates [OR = 0.35, 95% CI (0.20, 0.62), P = 0.0003]. The FE model also showed a significant difference in Karnofsky Performance Scale (KPS) scores [OR = -6.94, 95% CI (-10.39, -3.48), P < 0.0001]. Subgroup analysis for age and gender revealed no significant differences. This research model's robustness suggests that acupuncture and moxibustion, when used in combination, are more effective in treating patients with RE than control treatments. This effectiveness is evident in terms of significant effect proportion, cure rates, and KPS scores. These conclusions are consistent across different genders and ages.

To investigate the impact of perioperative rapid rehabilitation nursing on pelvic floor function of patients during transvaginal natural cavity endoscopic hysterectomy using perineal Four-dimensional (4D) ultrasound imaging technique. A total of 60 patients undergoing natural cavity endoscopic hysterectomy were evenly divided into control group (CG) and observation group (OG). The CG adopted perioperative nursing mode, and the OG adopted rapid rehabilitation nursing on the basis of the CG. The perineal 4D ultrasound imaging technology was used to evaluate the postoperative pelvic floor function parameters and the incidence of pelvic floor function abnormalities in the two groups. During anal retraction, the OG exhibited a substantially higher urethral rotation angle and bladder neck mobility compared to the CG (P < 0.05). Under resting conditions, the ultrasonic parameters of the two groups did not differ significantly (P > 0.05). The OG's ultrasonography parameters were substantially lower than the CG's under the highest Valsalva condition (P < 0.05). The incidence of internal urethral orifice infundification did not differ between the two groups (P > 0.05). Compared to the OG, the CG had a considerably higher incidence of cystocele (P < 0.05). There was a clear difference in pelvic prolapse distance between the two groups (P < 0.05). 4D ultrasound is conducive to accurately identifying the morphological structure and function of the pelvic floor in patients with hysterectomy, and provides guidance for the formulation of the rehabilitation treatment plan for the pelvic floor muscle of the patients.

To reduce the fluid resistance on the surface of flow-through components and improve energy utilization efficiency, a biomimetic fitting structure model is constructed based on the ridge-like features of beluga skin. The SST k-ω model is employed to numerically simulate the drag reduction characteristics of three biomimetic structures (fitting structure, V-shaped structure, and arc structure) included in the design. The variations of the fitting structure’s viscous resistance and pressure drop resistance with different widths and depths are compared. The drag reduction mechanism of the fitting structure surface is studied based on the pressure stress, velocity field, and shear stress. The results demonstrate that the fitting structure exhibits the best drag reduction performance. The fitting structure with a width of 30 mm and a depth of 0.7 mm achieves an optimal drag reduction effect of 4.18%. The fitting structure exhibits a large low shear stress region, which increases the thickness of the bottom boundary layer, thereby reducing surface velocity and viscous resistance.

This study examined the drag reduction properties of cylindrical flows across various asymmetric notched structures through numerical simulation and particle image velocimetry. The focus was on investigating the influence of the number of asymmetric grooves on the drag characteristics, including the mean drag, spectral characteristics, time-averaged streamlines, separation point prediction, time-averaged pressure, wake vortex strength, Reynolds stress, and turbulent kinetic energy. The results showed that the presence of asymmetric grooves significantly influenced these flow parameters. Notably, the improvement was optimal in the four-groove configuration, evidenced by the lowest mean drag coefficient (0.804), vortex shedding frequency (2.74 Hz), recirculation area length (1.208D), and pressure difference across the cylinder (81.76). Moreover, this configuration resulted in the weakest trailing vortex, a 45% reduction in the maximum Reynolds stress (0.011), and a 40.5% decrease in the maximum turbulent kinetic energy (0.05). Thus, the presence of asymmetric grooves had a significant positive effect on the cylindrical flow properties, though the degree of improvement decreased with further increase in the number of grooves.

The results of large-eddy simulations are presented to illustrate the flow structures generated by the interaction of synthetic jets with a crossflow. The coupled calculations involving the internal flow of the actuator cavity and the external flow are performed using the ANSYS-Fluent software. The influence of the orifice shape (round orifice and rectangular orifices with aspect ratio of 6, 12, or 18) on the evolution of coherent structures is analyzed, and the effects of the jet-to-crossflow velocity ratio (0.5, 1.0, or 1.5) on the turbulent flow behavior are examined. The results show that the first vortex ring shed from the rectangular orifice lip behaves as a plate-like vortex. The horseshoe vortex and first vortex ring are followed by a trailing jet in the case of a round orifice, but this configuration is rarely identified when the orifice is rectangular. For the rectangular orifice with an aspect ratio of 18, the plate-like vortex splits into vortex filaments that become interwoven with the center of the synthetic jet. In general, at the same characteristic velocity, the round-orifice synthetic jet has a stronger capacity for normal penetration into the crossflow, whereas the rectangular-orifice synthetic jet with a large aspect ratio develops closer to the wall. For the rectangular orifice with a large aspect ratio, the development of the synthetic jet is restricted to a small region near the wall at a small jet-to-crossflow velocity ratio.

A substantial number of women throughout the world are affected with breast cancer, a dangerous and sometimes deadly condition. The creation of precise prediction models to determine the chance of survival in breast cancer patients has drawn increasing attention in recent years. The use of backpropagation neural networks (BPNNs) to forecast breast cancer patient survival is investigated in this study.

A total of 198 patients with early breast cancer who were treated in our hospital were selected The control group received traditional breast cancer radical mastectomy and radiotherapy, and the experimental group received mastoscopy Adjuvant nipple-areola complex (NAC) modified radical mastectomy combined with prosthesis implantation and radiotherapy was used to compare the surgical conditions, postoperative complications, patient satisfaction and living standards in two groups.

The range of change was small, and the difference was statistically significant (P<0.05) ;in the laboratory group, patient dissatisfaction was noticeably raised over that in the standard group, and the discrepancy was politically sensitive (P<0.05); over that in the control group, the scores of all dimensions of survival quality were appreciably raised over that in the laboratory group, and the correlation was striking (P<0.05). Survival quality was greatly expanded in the experimental and postoperative groups at 3 and 6 months postoperatively before surgery, and the difference was statistically significant (P<0.05);

The study demonstrates that BPNN-based predictive models can be useful tools for improving the accuracy of breast cancer survival rate prediction, thus aiding in more effective treatment planning and decision-making for breast cancer patients.

As one of the most important means of transportation, high-speed trains have a large capacity for carrying passengers. However, their narrow carriages can easily exacerbate the spread of respiratory diseases. Just like personalized ventilation in an airplane, ventilation in seat armrests of high-speed trains may increase comfort for passengers, but also influence the diffusion characteristics of respiratory pollutants. In this study, the effect of personalized ventilation in seat armrests, on the diffusion characteristics of respiratory pollutants in train carriages, is studied by means of the tracer gas method. Taking the ceiling air supply as the original ventilation system, comfortable temperature and pollutant diffusion characteristics of the personalized ventilation system, with 4 different air supply angles, are investigated. The 4 angles are 0°, 30°, 45° and 60°.  When the personalized ventilation with the above 4 angles is adopted, the fluctuation amplitudes of pollutants in the passenger breathing zone are reduced by 15.84%, 19.27%, 19.76% and 19.68%, respectively, compared with the original ventilation system. It indicates that the sensible use of personalized ventilation can effectively reduce the passengers’ contaminant concentrations in the breathing zone, thereby reducing the possibility of cross-contamination between passengers. In addition, the use of the personalized ventilation system leads to a slight improvement in the thermal comfort and flow uniformity in the carriage. Based on the results, personalized air supply with an angle of 45° is advised for use in high-speed trains.

The mixing of oil and gas forms the foundation of deep-sea oil and gas extraction and transportation. However, traditional conveying equipment has low efficiency and high failure rates. In this study, a spiral axial flow gas and liquid multiphase pump was used as the base model. The Eulerian multiphase flow model and RNG turbulence model were used for numerical simulations to analyze the internal flow field of the multiphase pump. A modification scheme was proposed to twist the airfoil shape and create a twisted vane. The twisted blade with the center of the hub-side flange chord length as the twisting center was twisted in the counterclockwise direction to help reduce the relative volume of gas in the flow channel. When the twisted vane with the hub-side airfoil type trailing edge point as the twisting center was twisted in the suction side direction, it helped to accelerate the movement of the gas-liquid mixture at the trailing edge of the back of the vane and further reduced the low velocity zone at the back of the vane. When the twist center is located at the hub side wing type trailing edge point of the twist vane, the twist degree is 0.214. This results in the maximum head and efficiency of the pump, improves gas phase aggregation phenomenon, and enhances the performance of the multiphase pump.

Slurry transport pumps, the central equipment of deep-sea mining (DSM) systems, provide the lifting power required for lifting mineral ores from the seafloor to the surface. The current technical challenges are associated with transport security and the economic aspects of coarse ore particles in pumps and pipelines. This paper focuses on the transportation characteristics of slurry pumps and uses theoretical methods, numerical calculations, and experimental methods to identify a feasible working mode. The geometric parameters of impeller channels in pump hydraulics significantly influence the migration properties of particles which in turn affects the overall security and economy of the system. The ratio of the impeller cross-sectional area F2/F1 (F1: cross-sectional area of the impeller outlet; F2: cross-sectional area of the impeller inlet) affects the particle passing capacity but negatively impacts pump efficiency. The percent of particles in the excellent passage interval of 0.2 s to 0.25 s increases from 25 to 43% when the number increases from 1.57 to 2.51. The pump behavior increases of the head by 5–10 m, and the efficiency decreases by 5–10%. So, the recommended span of F2/F1 is 1.57–2.00, and satisfying particle passing ability and efficiency can be achieved in this range. This study can provide a reference for the commercial transportation of slurry ores for deep-sea mining systems.

The slurry pump, which forms the core equipment of the deep-sea mining (DSM) system, provides lifting power for the ore from the seabed to the sea level, which is crucial for the safety of coarse ore particle transportation. Velocity slip plays a significant role in revealing the migration of the pump particles. Therefore, this study analyzes the velocity slip in a slurry pump using the computational fluid dynamics–discrete element method (CFD-DEM) for the first time. The relationship between the pump head and velocity slip was proposed and verified in this study based on the velocity triangle and Euler equation of the solid-liquid two-phase flow in the impeller. The effects of different particle sizes on the velocity slip are compared in detail. According to the computational results, the head depends on the larger velocity slip of the impeller outlet and lower velocity slip at the inlet. The peak value of the velocity slip was significantly reduced, and the peak position of the velocity slip and zero-point position moved backward for particle sizes ranging between 5-15 mm. This study provides a reference for the problems of particle migration and velocity slip in slurry pumps.

Because the helical axial flow gas-liquid mixing pump has the great advantage of conveying gas-liquid two-phase mixed medium, it has become the main core equipment for deep-sea oil and natural gas exploitation. The gas phase aggregation and bubble movement trajectory in the impeller channel have been widely studied, but the increase of medium flow resistance caused by flow separation has not been deeply discussed. Combined with the Euler multiphase flow model and the SST k-ω turbulence model, the numerical calculation of the helical axial flow gas-liquid mixed pump is carried out. Under design flow conditions Q = 100 m3/h, head H = 30 m, speed n = 4500 r/min, specific speed ns =213.6 r/min, and under different inlet gas content conditions, the influence of the bionic waveform leading edge blade on drag reduction characteristics of the helical axial flow gas-liquid mixed pump was investigated. By designing the blade with a leading-edge structure with different heights and pitches, the separation of the mixed medium and the suction surface is effectively suppressed, and the flow resistance of the medium in the 1/10 area of the inlet end of the blade is reduced. The results show that when the height A is 0.25%L and the pitch λ is 12.5%h, the maximum drag reduction rate in this region is 52.6%, the maximum increase in efficiency of the mixed pump is 2.2%, and the maximum increase in head is 4.8%. This study can provide technical support for flow drag reduction in gas-liquid mixed pump.

Venturi bubble generators have been extensively studied because of having a simple structure and high foaming efficiency, while producing a uniform bubble size. The effect of a noncondensable gas on hydraulic cavitation was considered to improve the Zwart-Gerber-Belamri cavitation model. This improved model and a population balance model were used to study the effect of cavitation on bubble fragmentation. The CFD-PBM results were compared with experimental results, and the accuracy of the improved calculation method was verified in terms of the distributions for the cavitation cavity, gas phase, and bubble size. The calculation results showed that increasing the noncondensable gas content over a certain range promoted the development of hydraulic cavitation, and the cavitation intensity could be indirectly controlled by adjusting the noncondensable gas content. With increasing cavitation intensity, the average bubble size decreased, and the bubble size distribution became narrower. Therefore, a high-pressure pulse generated by cavitation could effectively break bubbles. The development process of microbubbles was studied. The main controlling factors for bubble formation were determined to be the turbulent shear force of the fluid and the collapse impact force of the cavitation group, which provides a theoretical basis for optimizing the design of bubble generators.

The aerodynamic performance of four train models with different windshield configurations (i.e., internal and/or external) in three train marshalling modes (i.e., 3, 6 and 8-car groups) was numerically investigated in this study. The train's airflow characteristics at Re=2.25×106 were determined using the shear stress transport (SST) k-  turbulence model. The results were validated by comparing the pressure distributions and drag forces on the streamlined heads with experimental data. The difference in windshield configuration and train length has a substantial influence on the train’s flow field and surface pressure distribution. For the trains with internal windshields, due to non-uniform geometry, the flow is separated and vortices are formed at the windshield area. The boundary layer profile increases with the increased train length, and its thickness varies with windshield configurations. Asymmetric vortices are formed in the wake at a distance close to the tail car’s nose, except for trains with external windshields. The reduction of the flow velocity as the train length increases causes a reduction of the low pressure near the tail car’s streamline transition, thus causing a decrease in the tail car’s drag and lift forces. Consequently, for trains with external windshields, the head car’s drag increases, whereas the total train drag reduces significantly as the train length increases. Therefore, employing external windshields in all the inter-carriage gap sections, irrespective of the train length, demonstrates a good ability to reduce future train’s aerodynamic drag.

Urban electric multiple units (EMUs) is based on high-speed trains and metro vehicle technology. Their design speeds are generally from 160km/h to 200km/h, which mitigates the low operating speeds of metro vehicles. Traditional crosswind calculations for the aerodynamic characteristics of trains often assume a 3-marshalling train. Urban trains are generally 4-marshalling and 6-marshalling. Evaluating the aerodynamic characteristics of urban EMUs of different marshalling lengths is instructive for system design. Based on CFD, aerodynamic models of urban trains are established. The train models include 3-marshalling, 4-marshalling and 6-marshalling. The aerodynamic characteristics of 200km/h urban trains subject to different crosswind velocities are numerically simulated. The research display that the aerodynamic performance of the head-car and the first middle-car, under the same crosswind velocity, of different marshalling lengths, are almost the same, whereas the aerodynamic characteristics of the tail-cars for different marshalling lengths are significantly different. The side forces of the 4 middle-cars of the 6-marshalling train decrease, sequentially. At a crosswind velocity of 35m/s, 34% difference in Fs of the tail-car of a 6-marshalling train compared to a 3-marshalling, and the overturning moment differs by 22.8%. Because of the significant difference in side force and overturning moment, the three-marshalling train model cannot represent the real train. Therefore, the real marshalling length should be used, as far as possible, when studying crosswind effects on the train.

The flow in the vertical long-axis fire pump exhibits complex, three-dimensional, unsteady flow features. In an attempt to understand the effects of turbulence models on the flow mechanism and performance characteristics of the pump, the ANSYS CFX software was used to carry out numerical studies on the vertical fire pump using URANS. The main objective of this study was to investigate the unsteady flow dynamics within the vertical fire pump and the influence of applying different computational turbulence models. The study then sought to conduct a brief analysis of the unsteady pressure pulsation characteristics of the pump. The reliability of the CFD model was validated with an external characteristic test. The transient pressure distribution, velocity field and external characteristics were analyzed. The results were compared to experimental results, where it was revealed that the SST k-ω model showed 1.82% and 0.81% improvements in efficiency and head, respectively, over the k-ε models. In terms of the power performance, however, the standard k-ε is less likely to over-predict the power used by the pump in overload conditions as compared to the other turbulence models. The pressure charts did not show significant reactions to varying turbulence models across all the studied flow rates. However, the velocity streamlines revealed that there were several disruptions in streamwise flow, where both the standard and RNG k-ε models exhibited more recirculation areas than the SST k-ω and standard k-ω models. Overall, for this type of application, SST k-ω was the best-performing turbulence model, while RNG k-ε showed the poorest performance. Nonetheless, the RNG k-ε also has its strengths. This investigation would serve as a theoretical reference for further research and development in fluid machinery.

This study aims to perform quality control (QC) practices for setup reproducibility during radiotherapy for nasopharyngeal carcinoma (NPC) using statistical process control (SPC) tools.

A total of 480 fractional images from 48 NPC patients with the first 10 fractions of the treatment were collected. In QC practices, setup errors were described using the histogram and normal curve, cumulative frequencies of absolute setup errors and 3D Euclidean Distance (Eu) were analyzed; the X ̅-S chart and process capability index (Cpk) with the variable Eu were utilized to identify whether the outlier occurred and to evaluate the QC process.

The translational setup error distributions were almost normal in Lateral, Longitudinal and Vertical directions and were narrower in Lateral and Vertical directions. Vertical translational errors and Eu with a larger magnitude sag appeared the most frequently. Between the couch sag and no sag, the Eu mean of 7 to 7 NPC patients with the same 3 patients was out of control and the standard deviation of Eu  of nil to 2 patients was outlier based on the X ̅-S chart, and the Cpk was 1.05 and 1.36 respectively, when the specification limit of translational errors was ±3 mm.

Daily imaging is necessary to increase setup reproducibility for NPC patients and more measures should be taken to facilitate quality assurance procedures. SPC is better applied to QC practices depending on the reliable data and the acceptable tolerance levels in further studies.

To explore the feasibility of three radiotherapy techniques to realize simultaneous modulated accelerated radiation therapy for elective brain (SMART-Brain) in patients with 1-3 brain metastases.

Intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) were utilized to design radiotherapy plans for 20 patients with 1-3 brain metastases from lung cancer who underwent SMART-Brain, and the dosimetry parameters of the target volume and organs at risk (OARs) were compared.

For planning gross tumor volume (PGTV), D98% (near minimum) and conformity index (CI) of VMAT plan were significantly better than IMRT plan. For the planning target volume 1 (PTV1), HT plan provided better D98%, D2% (near maximum dose), V30Gy (target volume percent of 30Gy dose covering) and CI. In terms of the expose dose of hippocampus, HT plan had advantages in Dmean (mean dose), and its Dmax (maximum dose) was equivalent to VMAT plan, which was better than IMRT plan. HT and VMAT plans had a lower Dmax of optic chiasm, and VMAT plan was better in terms of dose limitation of scalp. In terms of lens protection, IMRT and VMAT plans were better than HT plan. There was no statistical difference in other dosimetry parameters.

For most patients, all three radiotherapy techniques met clinical requirements. VMAT and HT plans were superior to IMRT plan. It was recommended that VMAT or HT radiotherapy techniques should be selected to implement SMART-Brain according to the local reality of the radiotherapy facilities.