Milestone progress of the HEPS booster commissioning

The high-energy photon source(HEPS)is the first fourth-generation synchrotron light source facility in China.The HEPS injector consists of a linear accelerator(Linac)and a full energy booster.The booster captures the electron beam from the Linac and increases its energy to the value required for the storage ring.The full-energy beam could be injected to the storage ring directly or after“high-energy accumulation.”On November 17,2023,the key booster parameters successfully reached their corresponding target values.These milestone results were achieved based on numerous contributions,including nearly a decade of physical design,years of equipment development and installation,and months of beam commissioning.As measured at the extraction energy of 6 GeV,the averaged beam current and emittance reached 8.57 mA with 5 bunches and 30.37 nm rad with a single-bunch charge of 5.58 nC,compared with the corresponding target values of 6.6 mA and 35 nm rad,respectively.This paper presents the physical design,equipment development,installation,and commissioning process of the HEPS booster.

Knowledge, attitudes, and practices regarding Covid-19 and their relationship with Covid-19 booster vaccination status among women with infertility

Objective:To elucidate the relationship among knowledge,attitudes,and practices regarding Covid-19 and their relationship with booster vaccination status among women with infertility.Methods:This questionnaire-based cross-sectional study was performed online and offline among women with infertility who visited an infertility clinic in Jakarta,Indonesia.We assessed the patient’s knowledge,attitudes,and practices regarding Covid-19 and their relationship with booster vaccination status and sociodemographic profile.Results:A total of 178 subjects participated in this study,and most participants(92.6%)had received booster Covid-19 vaccines.From the questionnaire,74.2%had good knowledge,and 99.4%had good attitudes regarding Covid-19;however,only 57.9%of patients had good practices.A weak positive correlation existed between knowledge and attitudes(r=0.11,P=0.13)and a moderate negative correlation between attitudes and practices(r=-0.44,P=0.56).Participants’knowledge about vaccines and infertility was correlated with booster vaccination status(P=0.04).Academic background(P=0.01)and attitudes(P=0.01)were also correlated with booster vaccination status.The significant determinants of hesitance of receiving Covid-19 booster vaccines were high school education or below(OR=0.08,95%CI 0.02-0.36)and poor practices(OR=0.21,95%CI 0.05-0.95).Conclusions:The majority of the participants had received the Covid-19 booster vaccine and had good knowledge and attitudes but poor practices regarding Covid-19.Most participants had poor knowledge about the relationship between infertility and the Covid-19 vaccine.The general population should be more informed and reminded about practices to prevent Covid-19 and the relationship between vaccination and fertility to increase the number of people who receive Covid-19 booster vaccines.

Solid Rocket Booster Thrust Asynchrony Identification Method for Solid Rocket Bundled Rockets With ESO

The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.

Mushroomβ-glucan and polyphenol formulations as natural immunity boosters and balancers:nature of the application

Mushrooms are experiencing a kind of renaissance as a part of the contemporary human diet.These valuable organisms are more than food,they fit in perfectly as a novel market group known as nutra-mycoceuticals.Immune-balancing mushroom dietary fibers and secondary metabolites such as polyphenols are the main focus of the healthcare industry.Wellness and cosmetic companies are increasingly using mushroom extracts rich in these ingredients.This review considers the basic molecular immunomodulatory mechanisms of action of the most commonly used mushroom dietary fibers,β-glucans.The literature data on their bioavailability,metabolic transformations,preclinical and human clinical research,and safety are discussed.Immunomodulatory mechanisms of polyphenol ingredients are also considered.These molecules present great potential in the design of the new immunity balancer formulations according to their widespread structural diversity.Finally,we draw attention to the perspectives of modern trends in mushroom nutraceutical and cosmeceutical formulations to strengthen and balance immunity.

Intention and hesitancy to receive a booster dose of COVID-19 vaccine among pregnant women using a health belief model: A cross-sectional study

Objective:To examine the pattern of COVID-19 infection and vaccination,and to explore pregnant women’s willingness and reluctance to accept a booster dose of the COVID-19 vaccine.Methods:This was a cross-sectional,descriptive study with a convenient sample size using a structured questionnaire among pregnant women attending the gynecology and obstetrics department at Acıbadem Mehmet Ali Aydinlar Hospital,Istanbul,Türkiye.The Health Belief Model scale was used to assess the intention and reluctance to accept a booster dose of the COVID-19 vaccine.Results:A total of 145 participants,with a mean age of(33.5±4.8)years,and a gestational age of(30.9±7.3)weeks,were enrolled in this study.88.8%Received full doses of the Pfizer-BioNTech vaccination.47.8%Participants suffered from vaccine adverse effects.Health Belief Model demonstrated a significant finding of perceived susceptibility(P<0.001),perceived severity of COVID-19 complications(P<0.001),and perceived benefits regarding a booster COVID-19 vaccination(P<0.001).Conclusions:Most pregnant women who received the COVID-19 immunization express a significant intention to receive a booster dose,regardless of the adverse effects experienced from the previous doses.However,a small percentage of the study sample express hesitancy about receiving the booster dose.

猎鹰9号火箭发射及箭体复用的分析

猎鹰9号火箭截至2023年年底已完成286次发射。对猎鹰9号火箭特别是Block5版本火箭的发射情况进行了完整梳理统计,重点分析了一级箭体的复用情况以及发射、回收的相关能力保障,对火箭的经济性和未来前景作了预测。

数据资产、人力资本升级与企业价值

在数字经济时代,数据资产在企业价值创造过程中发挥重要作用。区别于数据资产的规范性研究,本文采用文本分析法构建上市公司的数据资产指标,以2009—2020年沪深A股上市公司为样本,检验了数据资产对企业价值的影响,并进一步探讨了人力资本升级在数据资产影响企业价值过程中发挥的中介效应。研究结果表明:第一,数据资产是提升企业价值的有效驱动力,该结论经过一系列内生性分析和稳健性检验后依然成立;第二,从中介效应来看,数据资产带来的人力资本升级,即员工教育水平和技能水平的提高有利于提升企业价值;第三,对于高科技企业、非国有企业、行业竞争程度高的企业而言,数据资产对企业价值的提升效果更加显著。本文从企业价值的视角,检验了数据资产“入表”制度的有效性,不仅在理论上拓宽了数据资产领域的相关研究,也在实践中为企业利用数据资产优势赋能企业价值创造,发展新质生产力提供了有益参考。

Retrospective analysis of early COVID-19 vaccine efficacy in older individuals receiving primary cycle, first booster and second booster

Background:We analysed data garnered during the ongoing Italian nationwide coronavirus disease 2019(COVID-19)vaccination campaign for comparing early COVID-19 monovalent vaccine efficacy in older persons who received the primary vaccination cycle,the first vaccine booster,and the second vaccine booster.Methods:We conducted a retrospective analysis of early COVID-19 monovalent vaccine efficacy(i.e.,within 120 days)against COVID-19 related hospitalizations,intensive care unit(ICU)admissions and deaths in older persons(i.e.,aged≥80 years),by accessing official data of the COVID-19 national integrated surveillance program instituted by the Italian National Institute of Health.Vaccine efficacy was compared(odds ratio;OR)among cohorts receiving the primary vaccination cycle,the first vaccine booster,and the second vaccine booster.Results:A consistent decline could be seen in the rate of COVID-19 hospitalizations,ICU admissions and deaths with increasing number of monovalent immunizations.Within 120 days of administration,the first and second vaccine boosters had superior efficacy compared to the primary vaccination cycle,reducing the odds of all endpoints between 62%-71%and 69%-84%,respectively.A modestly superior early efficacy could also be noted for the second versus the first monovalent vaccine booster(ORs of all endpoints further reduced by 18%-48%).Conclusion:Since an increasing number of immunizations is associated with a lower risk of unfavourable COVID-19 outcomes,vaccine boosters may be useful for limiting the clinical burden of this infectious disease in elderly populations.

有源缓冲型逆变器功率解耦技术研究

为实现单级单相升压逆变并能有效抑制直流侧二次纹波电流,提出一种带有源缓冲的电流型逆变器电路拓扑,研究该逆变器的6种电路模态并提出其两模态调制策略和三模态调制策略,设计2种调制策略下的模型预测控制策略,提供主电路参数设计准则。从储能电感电流的最大脉动量与二次纹波含量两方面对2种调制策略进行对比分析,得出了三模态调制策略具有更好纹波抑制效果的结论。对2种调制策略下的逆变器进行仿真分析,仿真结果表明,三模态调制下电路的输出电压总谐波失真率、电感电流相对脉动量与二倍频含量均低于两模态调制下的数据。设计并搭建500VA 48VDC/220V50HzAC有源缓冲型单级单相升压逆变器实验装置,给出了三模态调制下基于模型预测控制的逆变器实验波形,进一步证实了所提研究方案在实现单级升压逆变的同时具有二次纹波抑制能力。

一种用于微能量收集的升压电荷泵设计

开关电容直流-直流(Direct Current-Direct Current,DC-DC)变换器是电源管理系统中极其重要的一部分,升压电荷泵是其中的一个分支。在微能量收集的应用场景中,升压电荷泵的研究热点是实现低的泄漏电流和低的阈值电压损耗。多数升压电荷泵设计为了减少阈值电压损耗和电荷共享等非理想效应,使泄漏电流增大,或结构变得复杂,导致面积增大,不适用于微能量收集场景。Dickson电荷泵是早期的电荷泵结构,其结构简单实用,但较大的阈值电压损耗是其最大的缺点。为此,本文基于Dickson电荷泵进行分析,采用TSMC 250 nm工艺,使用中等阈值电压(Medium Threshold Voltage,MVT)型金属氧化物半导体场效应晶体管(Metal-Oxide-Semiconductor Field-Effect Transistor,MOS)代替二极管,降低阈值电压损耗,再利用体源二极管偏置技术,进一步降低阈值电压损耗。本文利用Positive MOS(PMOS)管与Negative MOS(NMOS)管级联的形式,减少泄漏电流,且NMOS管采用深N阱工艺,避免加入辅助电路。仿真结果表明,本文的升压电荷泵结构设计具有较好的性能表现,达到了设计要求。

海上升压站上部组块运输及吊装全过程监测研究

为研究海上升压站上部组块在海上运输及吊装全过程的倾斜和振动情况,在上部组块一层主立柱安装4台双向倾角仪和4台三向加速度计,并从传感器硬件、数据采集终端、供电系统、监控平台进行监测系统设计,实现了上部组块在运输及吊装全过程的倾斜姿态和振动加速度的实时监测,可为类似上部组块运输和吊装提供较好的借鉴。

解一类奇异摄动两点边界值问题的Booster方法

研究一类奇异摄动两点边界值问题,用Booster方法进行求解,使其收敛阶提高了O(εn+ 1 ) ,尤其在特殊加密网格上,使其收敛阶从O(N- 2 )提高到O(εn+ 1 N- 2 ) .其中ε为摄动小参数,n为渐近展开的阶数.最后给出了数值例子.

JHX-1不敏感传爆药的起爆与传爆特性研究

聚黑烯-1(JHX-1)是一种新型的不敏感传爆药。采用水悬浮工艺制备了JHX-1,通过模压成型工艺制备了不同尺寸的炸药药柱,利用电测法测试了JHX-1的爆速、临界爆轰直径以及爆轰增长距离。结果表明:JHX-1具有较低的机械感度,摩擦感度最高为8%,撞击感度最高为4%;97%理论最大密度时的爆速为(8432±25)m/s;临界爆轰直径小于5 mm,在临界起爆压力下,爆轰增长距离不大于18 mm。JHX-1在保持不敏感性的同时,具备了良好的起、传爆稳定性。

气泵和压缩机热回收系统的实测性能比较

为了有效回收空调机房排风热量,提出气泵和压缩机热回收系统,设计出样机并应用于北京某实验基地的空调机房。当新风进口温度从3℃升至15℃时,通过实际测试获得了气泵系统和压缩机系统的制热量、功率、温度效率、新风出口温度、性能系数(COP)及节能率。结果表明:当新风进口温度低于7℃时,气泵系统性能较好;当新风进口温度高于等于7℃时,压缩机系统性能较好;与采用电锅炉相比,气泵系统和压缩机系统的节能率分别为38.85%、35.25%。

基于助推器无控再入稳定性分析的落点预示方法

运载火箭助推器分离后的落点预示对于安全区的管控及回收系统的设计十分重要,然而助推器再入过程由于失去姿态控制能力导致姿态运动范围大、运动规律复杂,传统型号往往采用极限偏差组合或六自由度打靶的手段来进行助推器落点范围的预示,存在预示范围过大、预示方法对落点预示范围正向设计指导意义不足的问题。采用一种基于非线性动平衡理论的分析方法,分析助推器无控再入过程三通道耦合姿态运动动态稳定特性,辨识固有周期性姿态运动模态,针对有限固有模态建立等效质点运动受力建模,快速、精确分析助推器分离后的落点范围,并能够对助推器特征参数对落区范围影响进行灵敏度分析,指导落区范围正向设计。仿真结果表明:该方法相较极限偏差组合法大幅提升助推器落点预示精度,相较六自由度打靶法更高效、更具有设计指导意义,为火箭助推类飞行器的航区安全性设计提供了重要支撑。

海上风电升压站运输过程中运动响应分析

为研究升压站运输过程中恶劣海况对运输船及升压站的影响,为升压站安全运输提供数据支持,基于势流理论使用MOSES软件建立船舶及升压站模型,使用频域分析方法进行运输过程运动响应幅值算子RAO数值分析,根据分析结果优化设计运输航线,避免计算极值海况下航行,并在设计航线下进行运输过程运动监测,监测数据与计算数据比较验证后,进一步结合设计航线及气象预报海况进行数据偏离分析。结果表明,计算运输过程响应幅值算子RAO结果满足升压站运输安全要求,同等输入条件下的计算结果与监测结果相近。研究结果可为升压站安全运输提供一定参考。

吸附破伤风疫苗加强免疫后7天抗体水平变化

目的 明确吸附破伤风疫苗加强免疫后早期破伤风抗体(tetanus antibody, TAB)水平变化情况。方法 对2019—2021年在晋江市罗山街道社区卫生服务中心就诊的1978年以后出生的已完成含破伤风类毒素疫苗(tetanus toxoid-containing vaccine, TTCV)免疫规划5年以上的269例受试者加强免疫1剂破伤风类毒素(tetanus toxoid, TT),观察免疫后7 d TAB水平变化。结果 269例受试者中,加强免疫前TAB<0.01 IU/mL和0.01~0.09 IU/mL的受试者分别占29.4%和70.6%;加强免疫后7 d, TAB≥0.01 IU/mL的受试者达82.9%,TAB≥0.10 IU/mL的受试者达37.2%;加强免疫前后,不同TAB水平的受试者比例差异有统计学意义(χ2=123.05,P<0.001)。加强免疫后7 d,男、女性受试者中TAB≥0.10 IU/mL的受试者分别占35.6%和38.7%;12~<21岁、21~<31岁和31~42岁组受试者中TAB≥0.10 IU/mL的受试者分别占55.3%、36.8%和20.3%。结论 已完成全程TTCV免疫规划5年以上人群TT加强免疫后7 d约1/3的受试者可以获得有效免疫保护。

高速运行齿轮泵的吸油空化与抑制

为揭示齿轮泵高转速运行时的空化发展规律,对装载机用大功率双联齿轮泵的吸油特性展开研究。通过全流域仿真模拟及试验,分析了转速、吸油压力对双联齿轮泵空化现象及输出流量特性的影响。结果表明,双联齿轮泵发生明显吸油空化的临界转速为2400 r/min,当转速大于2400 r/min后,泵内的气体含量骤增,严重影响输出流量的连续性和稳定性;双联齿轮泵的临界吸油压力为0.19 MPa,继续增大吸油口压力会增大泵出口的流量脉动,与入口为0.1 MPa相比,吸油压力为0.19 MPa时齿轮副1和齿轮副2的气体体积分数分别降低0.059和0.067,有效流量分别增大7.96%和9.24%。通过增压装置增加泵的入口压力,对齿轮泵空化的抑制以及有效流量的提升有明显的改善作用,具有工程实际意义。

柴油机电辅助增压系统匹配计算分析

电辅助增压是一种内燃动力机械上常用的有效方法,可解决传统柴油机在小负载时进气压力不足和高负载增压过大的难题。船舶柴油机的增压系统是本文的主要研究对象,并在此基础上完成了柴油机的电气控制系统、涡轮增压辅机模拟模型的建立与验证。结果显示模型仿真预测值与试验值误差不超过2%,模型较为准确。在此基础上,建立电动辅助增压发动机的仿真模型,分析其在低速工况下的动态特性,并探讨其对发动机热效率的影响规律。研究发现,透平和压气机的性能对综合能效有很大的影响。电机功率的增加的同时,缸内燃烧得到改善,有利于发动机低工况下动力性能提升。

助推器对巡飞弹气动特性和静稳定性的影响

针对助推分离舱外形对巡飞弹气动特性和静稳定性的影响,通过对船尾收缩比和分离舱外形设计的研究,分析了船尾收缩比和曲线过渡对改善气动特性和稳定性的机理,形成了“增大船尾收缩比-改善曲线过渡”的设计思想。结果表明:船尾收缩比是影响流动特性和气动特性的主要因素。增大船尾收缩比可以有效减小局部分离的面积,改善流动状况,改进后的零阻减小了1.5%~2%,静稳定度提高了1%~3%;在特定的船尾收缩比下,船尾与助推分离舱曲线过渡对阻力特性和静稳定性有一定改善效果。