Performance analysis of single-focus phase singularity based on elliptical reflective annulus quadrangle-element coded spiral zone plates

Optical vortices generated by the conventional vortex lens are usually disturbed by the undesired higher-order foci,which may lead to additional artifacts and thus degrade the contrast sensitivity. In this work, we propose an efficient methodology to combine the merit of elliptical reflective zone plates(ERZPs) and the advantage of spiral zone plates(SZPs) in establishing a specific single optical element, termed elliptical reflective annulus quadrangle-element coded spiral zone plates(ERAQSZPs) to generate single-focus phase singularity. Differing from the abrupt reflectance of the ERZPs, a series of randomly distributed nanometer apertures are adopted to realize the sinusoidal reflectance. Typically, according to our physical design, the ERAQSZPs are fabricated on a bulk substrate;therefore, the new idea can significantly reduce the difficulty in the fabrication process. Based on the Kirchhoff diffraction theory and convolution theorem, the focusing performance of ERAQSZPs is calculated. The results reveal that apart from the capability of generating optical vortices,ERAQSZPs can also integrate the function of focusing, energy selection, higher-order foci elimination, as well as high spectral resolution together. In addition, the focusing properties can be further improved by appropriately adjusting the parameters, such as zone number and the size of the consisted primitives. These findings are expected to direct a new direction toward improving the performance of optical capture, x-ray fluorescence spectra, and forbidden transition.

Terahertz quasi-perfect vortex beam with integer-order and fractional-order generated by spiral spherical harmonic axicon

We propose a new method to generate terahertz perfect vortex beam with integer-order and fractional-order. A new optical diffractive element composed of the phase combination of a spherical harmonic axicon and a spiral phase plate is designed and called spiral spherical harmonic axicon. A terahertz Gaussian beam passes through the spiral spherical harmonic axicon to generate a terahertz vortex beam. When only the topological charge number carried by spiral spherical harmonic axicon increases, the ring radius of terahertz vortex beam increases slightly, so the beam is shaped into a terahertz quasi-perfect vortex beam. Importantly, the terahertz quasi-perfect vortex beam can carry not only integer-order topological charge number but also fractional-order topological charge number. This is the first time that vortex beam and quasi-perfect vortex beam with fractional-order have been successfully realized in terahertz domain and experiment.

水平多层spiral型地埋管数值模拟研究及换热特性分析

本文基于COMSOL软件建立了水平spiral型多层地埋管群传热三维数值模拟模型,并对其换热性能和温度场进行分析研究。结果表明:对比水平spiral多层并联管群来说,远离注入端的地埋管管内温度相对较低。地埋管群周围地层温度有所升高,远离注入端的地层温度变化相对较小。地埋管群的换热量随循环流体的流速增加而增加,但增幅降低。在进行换热器设计时,应合理控制循环水的流速。3层螺旋地埋管群的换热量略高,但层间干扰明显,建议选用2层并联螺旋管群。

Contrast-Enhanced CT-Guided Core Biopsy of Retroperitoneal Masses

Objective: To evaluate the efficacy, feasibility and safety of contrast-enhanced CT-guided core biopsy of retroperitoneal masses. Materials and Methods: Contrast-enhanced CT-guided biopsy of retroperitoneal masses was performed in 26 patients. Histopathological diagnosis was obtained and accuracy was calculated. Two blinded radiologists determined feasibility of biopsy procedures on routine CT-guidance, and compared accessibility of target lesions using contrast-enhanced and non-contrast-enhanced CT. Results: Satisfactory samples were obtained in all 26 patients and pathological diagnosis was made in 24. Accuracy was 95.5%. Routine CT-guided biopsy punctures were not satisfaction in 4/26 patients, and contrast-enhanced CT scans rendered the target lesions more accessible in 16 patients. Conclusion: Contrast-enhanced CT-guided biopsy increases the feasibility of biopsy of retroperitoneal masses.

Effectiveness and Therapeutic Impact of CT-Guided Percutaneous Drainage for Deep Neck Abscesses

Objective: The purpose of this study is to evaluate the effectiveness and safety of CT-guided percutaneous drainage (CPD) in the management of deep neck abscesses. Factors associated with successful treatment in patients with DNA will be identified. Methods: We retrospectively studied 29 patients who presented to the department of otolaryngology with deep neck abscesses between April 2011 and April 2015. These 29 patients were managed with CPD after antibiotic therapy or needle aspiration failed. Data on patient demographics, location of infection, existing comorbidity, duration of hospitalization, treatment received, and complications were reviewed. Results: The average age of 29 patients, including 18 men and 11 women, was 56 years old. Abscess was found in parapharyngeal space (n = 16), submandibular space (n = 7), retropharyngeal space (n = 5) and pretracheal space (n = 1). The maximum transverse diameter of abscess ranged from 4.8 cm to 8.0 cm (mean 6.03 cm). Positive cultures were found in 24 cases and the most common pathogen found was Streptococcus viridans. Average hospital stay was 6.7 days. Deep neck abscesses were completely removed without residual in all patients. No one had complications and no one died during and after CPD. Conclusion: CPD is a safe and highly effective procedure for treating patients with deep neck abscesses who do not respond to antibiotics therapy. This technique can also provide reliable evidence on pathogens responsible for deep neck abscesses and help otolaryngologists choose effective treatment to achieve better clinical success rate. We recommend that most deep neck abscesses should be managed initially by CPD before resorting to open surgery.

Particulate flow modelling in a spiral separator by using the Eulerian multi-fluid VOF approach

The Euler-Euler model is less effective in capturing the free surface of flow film in the spiral separator,and thus a Eulerian multi-fluid volume of fluid(VOF)model was first proposed to describe the particulate flow in spiral separators.In order to improve the applicability of the model in the high solid concentration system,the Bagnold effect was incorporated into the modelling framework.The capability of the proposed model in terms of predicting the flow film shape in a LD9 spiral separator was evaluated via comparison with measured flow film thicknesses reported in literature.Results showed that sharp air–water and air-pulp interfaces can be obtained using the proposed model,and the shapes of the predicted flow films before and after particle addition were reasonably consistent with the observations reported in literature.Furthermore,the experimental and numerical simulation of the separation of quartz and hematite were performed in a laboratory-scale spiral separator.When the Bagnold lift force model was considered,predictions of the grade of iron and solid concentration by mass for different trough lengths were more consistent with experimental data.In the initial development stage,the quartz particles at the bottom of the flow layer were more possible to be lifted due to the Bagnold force.Thus,a better predicted vertical stratification between quartz and hematite particles was obtained,which provided favorable conditions for subsequent radial segregation.

Efficacy of multi-slice spiral computed tomography in evaluating gastric cancer recurrence after endoscopic submucosal dissection

BACKGROUND Recurrence is the major challenge facing endoscopic submucosal dissection(ESD)-based treatment therapies for early gastric cancer(EGC).Urgent development of simple and easy surveillance approaches will enhance clinical treatment of the disease.AIM To explore the role of computed tomography(CT)recurrence in evaluating EGC after ESD treatment.METHODS We retrospectively recruited patients from our endoscopy department,between January 2002 and December 2015,and analyzed their basic characteristics,including symptoms,CT results,and results of endoscopy with biopsy,among others.RESULTS Among a total of 2150 patients EGC patients surveyed,1362 met our inclusion and exclusion criteria and were therefore enrolled in our study.The cohort’s sensitivity of CT for recurrent GC and specificity were 44.22%and 43.86%,respectively,with negative and positive predictive values of 40.15%(275/685)and 48.01%(325/677),respectively.The area under the curve of arterial and venous CT values for recurrent EGC were 0.545,and 0.604,respectively.Receiver operating characteristic curve revealed no statistically significant differences between arterial and venous CT values for recurrent EGC.CONCLUSION Enhanced CT has superior diagnostic efficacy,but less accuracy,compared to gold standard techniques in patients with recurrent EGC.

Asymmetrical spiral spectra and orbital angular momentum density of non-uniformly polarized vortex beams in uniaxial crystals

To explore the effect of non-uniform polarization on orbital angular momentum(OAM) in anisotropic medium, in this work investigated are the evolution of the spiral spectra and OAM densities of non-uniformly polarized vortex(NUPV)beams in uniaxial crystals propagating orthogonal to the optical axis, and also the case of uniformly polarized vortex(UPV)beams with left-handed elliptical polarization. In the input plane, the NUPV beams present their spiral spectra of m-mode concentrated at m = l ± 1 modes rather than m = l mode, and reveal the relation among topological charge l, mode of spiral spectra m and the power weight value Rmexpressed by l=∑^(∞)_(m)=-∞Rm. is still satisfied for UPV beams in uniaxially anisotropic crystals, whereas for NUPV beams their relations are no longer valid owing to non-uniform polarization. Furthermore, the analysis indicates that the asymmetrical distribution of power weight of spiral spectra and the non-zero value in the sum of longitudinal OAM densities originate from the initial non-uniform polarization and anisotropy in uniaxial crystals rather than topological charges. In addition, the relation between spiral spectrum and longitudinal OAM density is numerically discussed. This work may provide an avenue for OAM-based communications,optical metrology, and imaging by varying the initial non-uniform polarization.

Minioptical Navigation System for CT-Guided Percutaneous Liver Procedures

Purpose: To evaluate a new miniature optical navigation system for CT-guided liver interventions. Material and Methods: A two-center, prospective study was performed with four interventional radiologists. A total of 20 patients had CT-guided liver biopsy or ablation interventions utilizing the CT-Guide? navigation system (ActiViews Inc., Wakefield, MA) between July 2011 and December 2011. The navigation system consists of a self-adhesive patientsticker printed with coincident colored and radio-opaque reference markers, a miniature disposable video camera that clips on and off an interventional instrument, and software loaded on a computer to display the navigation information. The primary end point was the frequency of a satisfactory instrument position for the intended intervention. Results: The cohort consisted of 13 males and 7 females with an average age of 63.1 years (range of 38 to 80). Most of the patients, 70%, underwent CT-guided liver biopsy while the remainder had CT-guided ablation therapy. The average lesion size was 3.1 cm (range of 1.1 - 6.9 cm). All of the interventions, regardless of lesion size, met the primary end point of satisfactory instrument positioning. There were no device-related or unexpected adverse events recorded. Only one patient had a mild adverse event and it resolved without intervention. Conclusions: This study demonstrated the safety and effectiveness of the CT-Guide? navigation system for CT-guided liver interventions, for both biopsies and ablations. The targeting success rate for a satisfactory intervention was 100% with the system.

Percutaneous CT-Guided Drainage of Gastric Leaks Post-Sleeve Gastrectomy

Objectives: The aim of this study was to assess the safety and efficacy of percutaneous CT-guided drainage of gastric leaks post sleeve gastrectomy. Methods: For this single-center retrospective study, we reviewed the clinical data of 78 patients (44 men and 34 women with an average age of 34.6 ±10.5 years and a body mass index (BMI) of 45 kg/m2 ±3.2) that underwent percutaneous CT-guided drainage of gastric leaks due to sleeve gastrectomy from September 2011 to September 2018. The outcome measurements were technical and clinical success, complications, and the need for revisional surgery. Results: The technical success rate of drain insertion was 97.5% (76/78 patients). All of the patients (76/76 patients) exhibited early clinical and laboratory improvement, and no emergency surgery was required. However, six patients underwent revisional surgery after 3 - 5 months for non-healing gastric leaks/fistulas. One patient had a major complication of active bleeding due to arterial injury;this was managed by transcatheter coil embolization. All patients underwent endoluminal stent placement and received antimicrobial therapy and nutritional support. Conclusion: Percutaneous CT-guided drainage of gastric leaks after sleeve gastrectomy is a safe, effective, and minimally invasive alternative to surgery. This technique is in line with other conservative measures (endoluminal stent placement, antimicrobial therapy, and nutritional support), which heal most gastric leaks due to sleeve gastrectomy and prevent the need for revisional surgery.

Numerical simulation of flow and heat transfer of n-decane in sub-millimeter spiral tube at supercritical pressure

The flow and heat transfer characteristics of n-decane in the sub-millimeter spiral tube(SMST) at supercritical pressure(p = 3 MPa) are studied by the RNG k-ε numerical model in this paper. The effects of various Reynolds numbers(Re) and structural parameters pitch(s) and spiral diameter(D) are analyzed.Results indicate that the average Nusselt numberNu and friction factorNu increase with an increase in Re, and decrease with an increase in D/d(tube diameter). In terms of the structural parameter s/d, it is found that as s/d increases, the Nu first increase, and then decrease. and the critical structural parameter is s/d = 4. Compared with the straight tube, the SMST can improve Nu by 34.8% at best, while it can improve Nu by 102.1% at most. In addition, a comprehensive heat transfer coefficient is applied to analyze the thermodynamic properties of SMST. With the optimal structural parameters of D/d = 6 and s/d = 4, the comprehensive heat transfer factor of supercritical pressure hydrocarbon fuel in the SMST can reach 1.074. At last, correlations of the average Nusselt number and friction factor are developed to predict the flow and heat transfer of n-decane at supercritical pressure.

Sound absorbing properties of spiral metasurfaces inspired by micro-perforated plates

As a kind of classical low-frequency sound-absorbing material,the microperforated plate(MPP)has been widely used.Here,we inspired by the sound absorption mechanism of the MPP,a spiral metasurface(SM)is designed and the analytical solution of acoustic impedance and sound absorption coefficient are obtained.The relationship between the sound absorption properties of the MPP and the SM with their own structures is systematically studied,and the analytical solutions are used to optimise the structure.It is concluded that the MPP and the SM of the same thickness achieve effective absorption in the frequency range between 390-900 Hz and 1920-4266 Hz,with a total thickness less than 1/6 of the wavelength.Meanwhile,the numerical calculation shows that the MPP and SM can match well with the background medium in the effective rang.Our study provides new insights into the design methods of sound-absorbing materials and is potentially suitable for many acoustic engineering applications.

A Model of Modified Newtonian Gravity Alternative to MOND, Consistent with the Properties of Spiral Galaxies and Compatible with Extragalactic Dark Matter

A new model of the modified Newtonian gravity called Compacted & Collapsing Gravity (CCG) is proposed. Similar to the Milgrom’s MOND, it allows explaining the flattening of rotation curve in spiral galaxies, thus eliminates the need for dark matter at this level. However, in contrast to MOND, it puts a distinct limit on effective gravity;thereby constraints the sizes of single galaxies in connection to their masses, which complies with observations. In the bigger than single galaxies structures such as galaxy clusters, CCG rather complements than replaces interpretations of the observational data based on dark matter. Besides, the new model provides a plausible explanation to the hierarchical structure of the universe.

CFD Analysis of Spiral Flow Fields in Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells(PEMFCs)are largely used in various applications because of their pollution-free products and high energy conversion efficiency.In order to improve the related design,in the present work a new spiral flow field with a bypass is proposed.The reaction gas enters the flow field in the central path and diffuses in two directions through the flow channel and the bypass.The bypasses are arranged incrementally.The number of bypasses and the cross-section size of the bypasses are varied parametrically while a single-cell model of the PEMFC is used.The influence of the concentration of liquid water and oxygen in the cell on the performance of different flow fields is determined by means of Computational fluid dynamics(COMSOL Multiphysics software).Results show that when the bypass number is 48 and its cross-sectional area is 0.5 mm^(2),the cell exhibits the best performances.

New Insights into the Action of Gravitons in Spiral Galaxies

New details of the action of gravitons in spiral galaxies are described. The effect of the graviton energy loss is hypothesized to be coupled to the baryon mass in the galaxy. From this relation, it follows that the baryonic Tully-Fisher relation is applicable to not just the final velocity of the galaxy but also to the rotational velocity at each radial position. In addition, a quadratic equation for the baryonic mass distribution is derived from the equation of motion. These results are demonstrated by making fits to galaxy rotation curves using a mass to light ratio model as well as the quadratic model for the mass distribution.

Imaging Effect and Accuracy Analysis of 64-Slice Spiral CT in the Diagnosis of Coronary Artery Stenosis

Objective:To analyze the imaging effect and accuracy of 64-slice spiral CT in the diagnosis of coronary artery stenosis.Methods:30 patients with suspected coronary heart disease admitted to our hospital from March 2022 to March 2023 were selected.All patients underwent both 64-slice spiral CT and digital subtraction angiography(DSA).DSA is considered the gold standard for diagnosis,so it was used to analyze the diagnostic performance of 64-slice spiral CT.Results:(1)The diagnostic results of digital subtraction angiography and 64-slice spiral CT was analyzed and compared with each other.The 64-slice spiral CT had an accuracy of 96.67%(29/30),a sensitivity 96.55%(28/29),and a specificity of 100.00%(1/1)in diagnosing coronary artery stenosis.(2)There was no significant difference between 64-slice spiral CT and digital subtraction angiography in the positive detection rate of anterior descending artery lesion,the positive detection rate of left main lesion,the positive detection rate of left circumflex artery lesion and the positive detection rate of right coronary artery lesion(P>0.05).(3)There was no significant difference between 64-slice spiral CT examination and DSA examination in identifying mild stenosis,moderate stenosis,and severe stenosis of coronary arteries(P>0.05).Conclusion:64-slice spiral CT examination can accurately determine the degree of occlusion of coronary arteries,which allows for the accurate diagnosis of coronary artery stenosis.

基于Res-UNet算法的螺旋溜槽精矿带识别分割方法研究

螺旋溜槽在铁、锡、钛、钽铌等金属及硫、煤等非金属矿的选矿生产中获大量应用,但目前螺旋溜槽的精矿截取调节控制还是依赖于人工,急需开发一种精矿的自适应截取技术代替人工截取以提高螺旋溜槽的生产效率。而实现这一目标的首要任务就是需要解决依赖人工肉眼获取精矿带位置信息的问题,因此提出了一个改进的UNet网络模型Res50-UNet-FD。算法模型使用UNet模型为基础,将残差网络ResNet50代替UNet网络中编码部分的特征提取网络,解决了深层特征提取过程中特征梯度消失以及网络消失的问题,有效提升了螺旋溜槽精矿带特征信息提取的精度。同时,为了改进和优化螺旋溜槽精矿带图像样本数据难易不平衡的问题,利用FocalLoss和DiceLoss的混合损失函数代替原本的CELoss损失函数。经对比,本文算法优于VGG-UNet、Res34-UNet、DC-UNet网络模型,算法模型的mIOU、mPA、F1分数和精确度分别为0.9632、0.9869、0.9870、0.9907。在性能指标上,本文算法无论是mIOU、mPA还是F1分数,整体性能都比VGG-UNet、Res34-UNet、DC-UNet网络模型高,算法的整体性能稳定。本文算法实现了对螺旋溜槽精矿矿带的分割识别,分割精度可以满足生产中对螺旋溜槽精矿分带特征信息识别的需求,为实现螺旋溜槽精矿的自适应截取奠定基础。

静态混合器结构优化设计与流场特性分析

为油田高能效驱油以提高原油产量,针对SK型和SX型静态混合器混合单元结构,通过创新设计和三维建模开发多重螺旋混合单元静态混合器,基于静态混合原理,利用FLUENT数值模拟软件,采用有限体积法,对所开发混合器内流体的流场进行仿真分析,研究该结构静态混合器的流动特性,结果表明,该种静态混合器使流体产生剪切和正反向涡旋作用,流体被充分扰动,混合均匀,满足油田注聚驱油要求,可为油田开发新型高效静态混合器提供一定技术支持。

重力引导螺旋型鼻肠管空肠置管操作流程及教学歌决

为了提高鼻肠管床旁定位的有效性和空肠置管的成功率,根据经典文献,结合自己的操作实践,编写了一个重力引导螺旋型鼻肠管空肠置管的操作流程及教学歌决。歌决内容:肠内营养寓胜算,空肠置管莫等闲。方法多样各神通,大力推广路漫长。半坐吞咽进食管,回抽自如识胃腔。右卧轻张过幽门,左卧低阻到空肠。胃内折返何征象?导管反弹最先见,充气受阻“折返征”,染色定位胜影像。真空试验最敏感,酸碱序变特异强,美蓝试验神答问,三法联用共导航。腹部平片金标准,超声时代仍可参。立体影像整体观,更有断层解疑难。此教学歌决以简明扼要、易于记忆的形式,成为临床手把手鼻肠管置管教学的有力工具。

基于子宫内膜结构与子宫螺旋动脉血流参数构建人工授精妊娠预测模型及验证

背景:现子宫内膜结构及子宫螺旋动脉血流参数对夫精宫腔内人工授精(artificial insemination by husband,AIH)妊娠率的影响水平尚不明确,该研究通过校准其他混杂因素后,确定了其独立影响因素,并构建了预测模型,具有较好的临床应用效能。目的:基于子宫内膜结构及子宫螺旋动脉血流参数构建AIH临床妊娠预测模型及验证。方法:回顾性分析2017年1月至2021年1月于常州市妇幼保健院接受AIH助孕治疗患者共1299例,将其中1182例未临床妊娠者纳入未妊娠组,117例临床妊娠者纳入妊娠组;通过1∶1倾向评分匹配,妊娠组与未妊娠组各匹配成功93例;采用单、多因素分析筛选子宫内膜结构及子宫螺旋动脉血流参数对AIH结局的影响因素,通过受试者工作曲线确定各独立影响因素的最佳截断值,限制性立方样条法分析各独立影响因素对AIH妊娠影响的风险趋势,临床决策曲线与临床影响曲线对该联合预测模型的临床应用效能进行检验。结果与结论:①倾向评分后妊娠组与未妊娠组各非内膜因素均无显著统计学意义,数据具有较好的均衡性(P>0.05);②单因素分析结果显示,内膜下血管化指数、血流指数、血管化血流指数、子宫动脉阻力指数、子宫动脉搏动指数、收缩期最高血流速度/舒张期末血流速度、基底子宫内膜到外子宫肌层内层平均交界区、最大交界区厚度为AIH妊娠的影响因素(P<0.05);③多因素Logistic回归结果显示,基底子宫内膜到外子宫肌层内层平均交界区厚度、子宫动脉搏动指数、血管化血流指数为AIH妊娠的独立影响因素,影响大小依次为血管化血流指数>基底子宫内膜到外子宫肌层内层平均交界区厚度>子宫动脉搏动指数;④受试者工作曲线显示,血管化血流指数的曲线下面积为0.704(0.629,0.779),最佳截断值为6.26;基底子宫内膜到外子宫肌层内层平均交界区厚度的曲线下面积为0.660(0.582,0.739),最佳截断值为6.38;子宫动脉搏动指数的曲线下面积为0.642(0.563,0.721),最佳截断值为1.18;⑤限制性立方样条曲线显示,当血管化血流指数>6.24时,其对AIH妊娠具有显著的正影响趋势;基底子宫内膜到外子宫肌层内层平均交界区厚度≤6.55 mm时,其对AIH妊娠具有显著的正影响趋势;当子宫动脉搏动指数>1.27时,其对AIH妊娠具有负影响风险;⑥临床决策曲线与临床影响曲线显示,该联合预测模型在阈概率值为0.17-0.93时具有临床最大净获益,且在该阈概率范围内损失与获益的比值始终小于1,显示出该联合预测模型具有较好的临床效能;⑦结果表明,通过倾向评分与多因素Logistic回归校正子宫内膜外其他混杂因素后,基底子宫内膜到外子宫肌层内层平均交界区厚度、子宫动脉搏动指数、血管化血流指数为AIH妊娠的独立影响因素,通过对其最佳截断值的确定与风险趋势性评估,证实该联合预测模型具有较好的预测价值与临床应用效能。