术前MSCT对胫骨平台骨折伴半月板损伤的诊断价值

目的探讨术前多层螺旋计算机断层扫描(MSCT)对胫骨平台骨折伴半月板损伤的诊断价值。方法回顾2017年1月至2022年12月聊城市第二人民医院收治的83例行胫骨平台骨折内固定术治疗病人的临床资料,术前均接受MSCT检查,以术中骨折复位内固定后即刻关节镜下所见有无发生半月板损伤为金标准分为半月板损伤组和无半月板损伤组。比较两组病人基线资料及MSCT参数,绘制受试者操作特征曲线(ROC曲线)分析MSCT参数对复杂胫骨平台骨折伴半月板损伤的诊断价值。结果83例胫骨平台骨折病人发生半月板损伤共39例(46.99%),Ⅳ型半月板损伤发生率为18.75%(3/16),低于Ⅱ型的59.52%(25/42)(P<0.05)。半月板损伤组中SchatzkerⅡ型占比高于无半月板损伤组,SchatzkerⅣ型占比及术前MSCT检测骨折切线至塌陷最低点距离、外侧髁切线至骨折块远端距离、塌陷相对面积高于低于无半月板损伤组(P<0.05)。ROC曲线分析显示,骨折切线至塌陷最低点距离、外侧髁切线至骨折块远端距离、塌陷相对面积单独及联合应用诊断胫骨平台骨折伴半月板损伤的ROC曲线下面积(AUC)(95%CI)为0.64(0.56,0.72)、0.70(0.62,0.78)、0.76(0.67,0.83)、0.89(0.83,0.94),联合应用的诊断价值高于单独应用(P<0.05)。结论术前MSCT测量胫骨平台骨折外侧髁切线至骨折块远端距离、塌陷相对面积等参数对半月板损伤的诊断有重要参考价值。

节能燃气加热器中折流板的应力分析与优化

为了研究加热器中暴露在高温环境下折流板的应力分布规律与安全可靠性,基于有限元分析方法对其进行应力分析,选取危险截面路径进行应力线性化分析,并根据安全评定结果对折流板结构进行优化.结果表明:尖角造成的应力集中对折流板的应力分布影响较大,其薄膜应力P L过高是导致应力评定危险的主要原因;折流板整体应力大小随着燃料进口速度的增大而增高,温度与热应力大小呈正相关,在不同速度下应力变化趋势相似,换热管束与折流板连接处的结构不连续会造成应力升高;优化方案中,当钝化尖角后,折流板最大热应力降低16.7%,再覆盖热障涂层时的最大热应力较钝化尖角时降低44.5%,较原始结构降低53.7%,且整体热应力下降,优化后折流板强度评定为合格.

采用提篮钢板技术治疗粉碎性髌骨下极骨折的疗效分析

目的探讨应用提篮钢板技术治疗粉碎性髌骨下极骨折的临床疗效。方法回顾性分析唐山市第二医院创伤一科2021年3月至2024年3月应用提篮钢板技术治疗的18例粉碎性髌骨下极骨折患者的临床资料,其中男10例,女8例,年龄21~73(44.1±14.2)岁;左膝7例,右膝11例;交通伤8例,摔伤10例。应用提篮钢板技术治疗粉碎性髌骨下极骨折。住院期间观察记录患者年龄、性别、术前疼痛评分(FPS-R)。患者出院后于术后6周、8周、10周、12周、6个月、12个月门诊复查随访,记录骨折愈合时间、膝关节屈曲康复时间、末次随访FPS-R,末次随访B?stman髌骨骨折疗效评分。结果18例患者术前FPS-R评分6(4,6)分,切口均一期愈合,无失访患者;随访时间6~12个月;骨折愈合时间8(6,8.5)周;膝关节屈曲康复时间:90°需3(3,4)周,120°需6(6,8)周,全范围需10(8,10)周;末次随访FPS-R评分2(0,2)分;末次随访B?stman髌骨骨折疗效评分29(28,30)分,优17例,良1例,优良率为100%。18例患者骨折愈合良好,未出现感染、切口愈合不良、内固定物失效、内固定激惹等并发症。结论应用提篮钢板技术治疗粉碎性髌骨下极骨折疗效确切、满意。该技术可达到骨折坚强内固定、早期功能锻炼的目的,术后并发症少,骨折愈合率高,膝关节功能恢复好,疗效优良率高。该技术内固定材料获取容易,手术技术简单,适合在基层医院推广应用。

板柱节点考虑弯剪相关性的受冲切承载力计算方法

对于同时受到竖向荷载和不平衡弯矩作用的板柱节点,目前已有方法大多将不平衡弯矩等效为竖向荷载,从而给出其受冲切承载力计算方法。但该方法所涉及的不平衡弯矩比例系数的计算还存在较大争议,且没有考虑竖向荷载与不平衡弯矩耦合的影响。因此,本文首先通过推导给出仅有竖向荷载作用的板柱节点受冲切承载力计算公式和仅有不平衡弯矩作用的板柱节点受弯承载力计算公式,并与试验结果进行对比,验证了所提公式的合理性。然后基于板柱节点在竖向荷载和不平衡弯矩共同作用下的试验结果,拟合得到板柱节点考虑弯剪相关性的受冲切承载力计算公式。最后对所提计算方法与不同规范计算方法进行对比,结果表明本文计算方法能够更加准确地预测板柱节点受冲切承载力。

基于“板-梁理论”单轴对称FGM工字形梁组合扭转

针对目前功能梯度材料(Functionally Graded Materials,FGM)工字形截面梁为研究对象的研究较少,本研究以“板-梁理论”为基础,以上翼缘为矩形实体单轴对称的工字形截面梁为对象,展开组合扭转理论研究。基于“板-梁理论”,推导总应变能方程,得到梁的翘曲刚度和自由扭转刚度,然后通过外力势能公式和总应变能公式逐步推导得出总势能表达式。在此基础上,利用能量变分模型和微分方程模型,结合边界条件,推导出梁端部最大扭转角计算公式,将求出的最大扭转角与ANSYS建立的有限元模型结果进行对比。误差最小为0.01%,误差最大为1.85%。本文推导了FGM沿宽度变化上翼缘为矩形实体单轴对称工字形梁的组合扭转总应变能表达式,给出了一端固定、一端自由边界条件下扭转角及最大扭转角的表达式,从而进一步验证“板-梁理论”的正确性。

Recent advancements in continuously scalable conversion-ratio switched-capacitor converter

Switched-capacitor(SC)DC-DC converter[1]is an impor-tant alternative to inductive DC-DC converter,in terms of removing the bulky power inductor.Hence,it is widely used in low-profile,low-power applications,such as the internet of things(IoT)sensor nodes and energy harvesting[2].Mean-while,considering that capacitor has a much higher energy density than inductor,high-power applications.

Modeling the System for Hybrid Renewable Energy Using Highly Efficient Converters and Generator

High-efficient isolated DC/DC converters with a high-efficiency synchronous reluctance generator(SRG)are the ultimate solutions in DC microgrid systems.The design and modeling of isolated DC/DC converters with the performance of SRG are carried out.On the generator side,reactive and active powers are used as pulse width modulation(PWM)control variables.Further,the flux estimator is used.Three-phase PWM rectifier is used by applying space vector modulation(SVM)with a constant switching frequency for direct power control.Further,the paper also includes the experimental validation of the results.The paper also proposes that highly efficient power converters and synchronous reluctance generators are required to achieve high performance for hybrid renewable energy systems applications.

A real-time calibration method based on time-to-digital converter for accelerator timing system

The high-intensity heavy-ion accelerator facility(HIAF)is a scientific research facility complex composed of multiple cas-cade accelerators of different types,which pose a scheduling problem for devices distributed over a certain range of 2 km,involving over a hundred devices.The white rabbit,a technology-enhancing Gigabit Ethernet,has shown the capability of scheduling distributed timing devices but still faces the challenge of obtaining real-time synchronization calibration param-eters with high precision.This study presents a calibration system based on a time-to-digital converter implemented on an ARM-based System-on-Chip(SoC).The system consists of four multi-sample delay lines,a bubble-proof encoder,an edge controller for managing data from different channels,and a highly effective calibration module that benefits from the SoC architecture.The performance was evaluated with an average RMS precision of 5.51 ps by measuring the time intervals from 0 to 24,000 ps with 120,000 data for every test.The design presented in this study refines the calibration precision of the HIAF timing system.This eliminates the errors caused by manual calibration without efficiency loss and provides data support for fault diagnosis.It can also be easily tailored or ported to other devices for specific applications and provides more space for developing timing systems for particle accelerators,such as white rabbits on HIAF.

Robust optical mode converter based on topological waveguide arrays

Optical mode converters are essential for enhancing the capacity of optical communication systems. However, fabrication errors restrict the further improvement of conventional mode converters. To address this challenge, we have designed an on-chip TE0–TE1mode converter based on topologically protected waveguide arrays. The simulation results demonstrate that the converter exhibits a mode coupling efficiency of 93.5% near 1550 nm and can tolerate a relative fabrication error of 30%. Our design approach can be extended to enhance the robustness for other integrated photonic devices, beneficial for future development of optical network systems.

Energy-Efficient Implementation of BCD to Excess-3 Code Converter for Nano-Communication Using QCA Technology

Code converters are essential in digital nano communication;therefore,a low-complexity optimal QCA layout for a BCD to Excess-3 code converter has been proposed in this paper.A QCA clockphase-based design technique was adopted to investigate integration with other complicated circuits.Using a unique XOR gate,the recommended circuit’s cell complexity has been decreased.The findings produced using the QCADesigner-2.0.3,a reliable simulation tool,prove the effectiveness of the current structure over earlier designs by considering the number of cells deployed,the area occupied,and the latency as design metrics.In addition,the popular tool QCAPro was used to estimate the energy dissipation of the proposed design.The proposed technique reduces the occupied space by∼40%,improves cell complexity by∼20%,and reduces energy dissipation by∼1.8 times(atγ=1.5EK)compared to the current scalable designs.This paper also studied the suggested structure’s energy dissipation and compared it to existing works for a better performance evaluation.

Modular System of Cascaded Converters Based on Model Predictive Control

A modular system of cascaded converters based on model predictive control(MPC)is proposed to meet the application requirements ofmultiple voltage levels and electrical isolation in renewable energy generation systems.The system consists of a Buck/Boost+CLLLC cascaded converter as a submodule,which is combined in series and parallel on the input and output sides to achieve direct-current(DC)voltage transformation,bidirectional energy flow,and electrical isolation.The CLLLC converter operates in DC transformer mode in the submodule,while the Buck/Boost converter participates in voltage regulation.This article establishes a suitable mathematical model for the proposed system topology,and uses MPC to control the system based on this mathematical model.Module parameters are designed and calculated,and simulation is built in MATLAB/Simulink to complete the simulation comparison experiment between MPC and traditional proportional integral(PI)control.Finally,a physical experimental platform is built to complete the physical comparison experiment.The simulation and physical experimental results prove that the control accuracy and response speed ofMPC are better than traditional PI control strategy.

Hydrodynamic Performance of An Integrated System of Breakwater and A Multi-Chamber OWC Wave Energy Converter

A multi-chamber oscillating water column wave energy converter(OWC-WEC)integrated to a breakwater is investigated.The hydrodynamic characteristics of the device are analyzed using an analytical model based on the linear potential flow theory.A pneumatic model is employed to investigate the relationship between the air mass flux in the chamber and the turbine characteristics.The effects of chamber width,wall draft and wall thickness on the hydrodynamic performance of a dual-chamber OWC-WEC are investigated.The results demonstrate that the device,with a smaller front wall draft and a wider rear chamber exhibits a broader effective frequency bandwidth.The device with a chamber-width-ratio of 1:3 performs better in terms of power absorption.Additionally,results from the analysis of a triplechamber OWC-WEC demonstrate that reducing the front chamber width and increasing the rearward chamber width can improve the total performance of the device.Increasing the number of chambers from 1 to 2 or 3 can widen the effective frequency bandwidth.

Design Method of Anti-Total Ionizing Dose Effect Hardening for Buck-Boost Converter

Buck-Boost converter in the total dose radiation environment will mainly bring the output voltage drift, linear adjustment rate and load adjustment rate decline and other effects, so that the output stability performance of the circuit deteriorates. Aiming at the problems of high cost,large layout area and poor universality caused by the traditional total ionizing dose effect hardening method based on process and layout, this paper proposes a total ionizing dose effect hardening design method with parallel monitoring and hardening, which can achieve total ionizing dose effect hardening at the circuit level without process. The anti-total dose capability of Buck-Boost converter is improved. The circuit design and physical implementation of the proposed method are verified based on 0.18 μm bipolar complementary metal-oxide-semiconductor(CMOS) double-diffused metal-oxide-semiconductor(DMOS)(BCD) process. The results show that the system gain decrease rate can be compensated from 19.2% to 6.2%, and the output voltage shift rate can be improved from 2.00% to 0.15% at a dose of 200×10^(3) rad(Si). Moreover, the load adjustment rate and linear adjustment rate are reduced. They are respectively decreased to 0.191 %/A and 0.093 %/V. This provides a new idea for the design of total ionizing dose effect hardening at circuit and system level.

Negative Stiffness Mechanism on An Asymmetric Wave Energy Converter by Using A Weakly Nonlinear Potential Model

Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentially be addressed by adopting a negative stiffness mechanism(NSM)in WEC devices to enhance system efficiency,even in highly nonlinear and steep 3D waves.A weakly nonlinear model was developed which incorporated a nonlinear restoring moment and NSM into the linear formulations and was applied to an asymmetric WEC using a time domain potential flow model.The model was initially validated by comparing it with published experimental and numerical computational fluid dynamics results.The current results were in good agreement with the published results.It was found that the energy extraction increased in the range of 6%to 17%during the evaluation of the effectiveness of the NSM in regular waves.Under irregular wave conditions,specifically at the design wave conditions for the selected test site,the energy extraction increased by 2.4%,with annual energy production increments of approximately 0.8MWh.The findings highlight the potential of NSM in enhancing the performance of asymmetric WEC devices,indicating more efficient energy extraction under various wave conditions.

Harmonic Impedance Modeling and Oscillation Analysis of Modular Multilevel Converter

To facilitate rapid analysis of the oscillation stability mechanism in modular multilevel converter-based high voltage direct current(MMC-HVDC)systems and streamline the simulation process for determining MMC impedance characteristics,a simplified mathematical simulation model for MMC closed-loop impedance is developed using the harmonic state space method.This model considers various control strategies and includes both AC-side and DC-side impedance models.By applying a Nyquist criterion-based impedance analysis method,the stability mechanisms on the AC and DC sides of the MMC are examined.In addition,a data-driven oscillation stability analysis method is also proposed,leveraging a global sensitivity algorithm based on fast model results to identify key parameters influencing MMC oscillation stability.Based on sensitivity analysis results,a parameter adjustment strategy for oscillation suppression is proposed.The simulation results from the MATLAB/Simulinkbased MMC model validate the effectiveness of the proposed method.

Extreme Responses of An Integrated System with A Semi-Submersible Wind Turbine and Four Torus-Shaped Wave Energy Converters in Different Survival Modes

Offshore wind power is a kind of important clean renewable energy and has attracted increasing attention due to the rapid consumption of non-renewable energy.To reduce the high cost of energy,a possible try is to utilize the combination of wind and wave energy considering their natural correlation.A combined concept consisting of a semi-submersible wind turbine and four torus-shaped wave energy converters was proposed and numerically studied under normal operating conditions.However,the dynamic behavior of the integrated system under extreme sea conditions has not been studied yet.In the present work,extreme responses of the integrated system under two different survival modes are evaluated.Fully coupled time-domain simulations with consideration of interactions between the semi-submersible wind turbine and the torus-shaped wave energy converters are performed to investigate dynamic responses of the integrated system,including mooring tensions,tower bending moments,end stop forces,and contact forces at the Column-Torus interface.It is found that the addition of four tori will reduce the mean motions of the yaw,pitch and surge.When the tori are locked at the still water line,the whole integrated system is more suitable for the survival modes.

ANovel Non-Isolated Cubic DC-DC Converter with High Voltage Gain for Renewable Energy Power Generation System

In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effectively enhance voltage gain and reduce device stress.To address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain DC-DC converter based on the traditional quadratic DC-DC boost converter by incorporating a SC and a SL-SC unit.Firstly,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power loss.Subsequently,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain converters.Then,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic performance.Finally,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are analyzed.The theoretical analysis’s correctness is verified through simulation and experimental results.The proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power loss.The proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy applications.It provides an effective solution to the issue of low output voltage in renewable energy power generation systems.

强脉冲光联合育阴润目方熏蒸及睑板腺按摩治疗MGD相关干眼

目的:探讨强脉冲光(IPL)联合育阴润目方熏蒸及睑板腺按摩治疗睑板腺功能障碍(MGD)相关干眼患者的效果。方法:前瞻性研究。选取2021-11/2023-11本院收治的MGD相关干眼患者198例396眼,随机分为对照组99例198眼采用育阴润目方熏蒸及睑板腺按摩治疗,观察组99例198眼在对照组基础上联合IPL治疗。比较两组患者疗效以及治疗前后眼部指标[泪膜破裂时间(BUT)、泪液分泌量(SⅠt)]、视觉质量[平均客观散射指数(OSI)、斯特列尔比(SR)、调制传递函数(MTF)]、泪膜脂质层厚度(LLT)、泪液中炎性因子[肿瘤坏死因子-α(TNF-α)和转化生长因子-β1(TGF-β1)]的水平变化情况。结果:所有患者均完成治疗及随访。与治疗前比较,治疗2 mo后两组患者BUT、SⅠt、SR、MTF、LLT水平升高,OSI、泪液中TNF-α、TGF-β1水平降低(均P<0.001),且观察组均优于对照组(均P<0.001)。结论:IPL联合育阴润目方熏蒸及睑板腺按摩治疗MGD相关干眼的效果显著,可以改善患者眼部指标、视觉质量和LLT,降低泪液中炎性因子的水平。

Recovery of Solid Oxide Fuel CellWaste Heat by Thermoelectric Generators and AlkaliMetal Thermoelectric Converters

A Solid Oxide Fuel Cell(SOFC)is an electrochemical device that converts the chemical energy of a substance into electrical energy through an oxidation-reduction mechanism.The electrochemical reaction of a solid oxide fuel cell(SOFC)generates heat,and this heat can be recovered and put to use in a waste heat recovery system.In addition to preheating the fuel and oxidant,producing steam for industrial use,and heating and cooling enclosed rooms,this waste heat can be used for many more productive uses.The large waste heat produced by SOFCs is a worry that must be managed if they are to be adopted as a viable option in the power generation business.In light of these findings,a novel approach to SOFC waste heat recovery is proposed.The SOFC is combined with a“Thermoelectric Generator and an Alkali Metal Thermoelectric Converter(TG-AMTC)”to transform the excess heat generated by both the SOFC and the TG-AMTC.The proposed TG-AMTC is evaluated using a number of performance indicators including power density,operating temperature,heat recovery rate,exergetic efficiency,energy efficiency,and recovery time.The experimental results state that TG-AMTC has provided an exergetic efficiency,energetic efficiency,and recovery time of 97%,98%,and 23%,respectively.The study proves that the proposed TG-AMTC for SOFC is an efficient method of recovering waste heat.

Study and Production of a Two-Stage DC/DC DC/AC Converter for Generating an Alternating Voltage from a Direct Voltage Supplied by a Photovoltaic Array

This article presents an ongoing study of the design of a DC-AC inverter using a single renewable energy source. The proposed approach makes it possible to produce an output with an H-bridge or full bridge and a single energy source. To this end, the performance of the inverter was studied first by means of a simulation and then with the implementation of an experimental device.