英国A Level选考制度的发展动因与内在逻辑——兼论对我国新高考选考改革的启示

英国普通教育高级程度证书(A Level)建立于1951年,是英国高校在招生过程中最认可的学术资格证书考试之一,以自由选考为制度特色。A Level选考制度历经1989年、2000年和2015年三次改革,分别以“扩充课程广度”“提升考试适应性”“提高考试选拔性”为问题聚焦,其制度设计逐渐趋于完善,实现高校选才和中学育人的双重功能。A Level选考制度在英国传统文化的影响下以自由为内核,在教育矛盾的张力中维系着卓越的学术标准,在时代发展的推动下以追求公平为依归。参考A Level选考制度的发展逻辑,中国高考综合改革未来应在“有限多样”的原则下增加学生的选择性,并通过完善科目的内部评估体系实现综合评价录取。

英国GCE A-Level物理考试试题内容及特点研究——以单元1为例

在统计近年来英国GCE A-Level物理考试单元1试题的基础上,分析该试卷的特点,研究了该单元试题的典型案例,并且讨论了GCE A-Level物理考试单元1试题对我国高考物理考试和评价的参考与借鉴价值。

Endogenous Levels of Polyamines under Water-Deficit Stress during Cotton’s Reproductive Development

Polyamines, putrescine (PUT), spermidine (SPD) and spermine (SPM) are implicated in plants’ responses under conditions of abiotic stress. Previous research in other crops has indicated that polyamines and changes in their concentrations are associated with drought tolerance under conditions of water-deficit stress;however, no information exists on cotton (Gossypium hirsutum L.). Growth chamber experiments were conducted with two cotton cultivars differing in drought tolerance, ST5288B2F (drought-sensitive) and Siokra L23 (drought-tolerant) in order to investigate the distribution of free polyamines, the effect of water-deficit stress on the polyamine metabolism of cotton reproductive units and their subtending leaves as well as the possible relationship between polyamines and drought tolerance in cotton. Our results showed that cotton ovaries contained significantly higher levels of total free polyamines compared to their subtending leaves under both control and water stress conditions. Water-deficit stress significantly increased PUT concentrations in ST5288B2F, while SPM levels significantly decreased in Siokra L23. The results indicated that water-deficit stress significantly affected cotton polyamine metabolism in reproductive structures and their subtending leaves;however, no clear relationship between drought-tolerance and changes in polyamine accumulation was established. Further research is needed to elucidate the mechanism according to which water-deficit stress affects polyamine metabolism.

油田三维地质多级建模策略与方法——以渤海湾盆地整装孤岛油田为例

三维地质建模应用于油田勘探开发的各个阶段,解决不同的问题时,对建模的规模、精度及要求也不同。分区块地质建模在井位部署、开发调整分析上可以起到一定的指导作用,但是各独立区块模型没有统一的标准,不能实现由小模型到大模型的拼接,制约了油田的整体勘探开发及规划工作。为了更好发挥地质建模在油田勘探开发全生命周期的精准作用,研究以渤海湾盆地整装孤岛油田为例,提出了油田—区块—储层单砂体构型的多级建模策略。使用具有自主知识产权的Direct、M^(3)地质建模软件,应用地质约束的地质统计学及嵌入式储层构型建模方法,实现了从大到小、整体到局部、笼统到精细。分层级刻画了油田的构造沉积演化特征、储层内部构型及油藏空间展布,建成了中国首例油田级亿万网格节点的三维地质大模型及分级模型,为深化地质认识、油藏开发潜力评价、整体开发调整提高采收率提供了有利的手段。多级三维地质建模技术既为技术人员提供了多学科一体化的交流平台,又为油田勘探开发提供了方向,是油田数字化管理的有力抓手,更是数字化、智能化油田发展的必然趋势。

一种考虑g敏感性的MIMU系统级标定方法研究

针对微机械惯性测量单元(micro-electro-mechanical-system inertial measurement unit,MIMU)中存在陀螺漂移的g敏感性以及因漂移误差大而无法进行自主方位对准问题,建立了MIMU系统级标定Kalman滤波状态空间模型,考虑g敏感性误差状态的影响,在量测方程中加入方位失准角变化率以增强g敏感性的状态估计可观性;直接采用外输入粗略初始方位角进行导航解算,降低地球自转角速度的影响,提高陀螺漂移估计精度。设计了一套完整的系统级标定转位编排方案,陀螺标定和加速度计标定相互依赖,共同协作完成MIMU系统级标定,能够有效分离出所有30个标定参数,利用某型号弹载MIMU进行了实物标定试验验证,分别用标定前后数据进行导航解算,对比导航结算结果发现标定后的3个方向的导航速度都降低了,加速度计的刻度因数和零偏标定精度更高。特别在MIMU存在多轴大角度转动情况下,近10 min内达到优于30 m/s的导航速度精度,验证了系统级标定具有较高的精度。

An enhanced GPU reduction at the warp-level

In recent years, graphical processing unit （GPU）-accelerated intelligent algorithms have been widely utilized for solving combination optimization problems, which are NP-hard, These intelligent algorithms involves a common operation, namely reduction, in which the best suitable candidate solution in the neighborhood is selected. As one of the main procedures, it is necessary to optimize the reduction on the GPU. In this paper, we propose an enhanced warp-based reduction on the GPU. Compared with existing block-based reduction methods, our method exploit efficiently the potential of implementation at warp level, which better matches the characteristics of current GPU architecture. Firstly, in order to improve the global memory access performance, the vectoring accessing is utilized. Secondly, at the level of thread block reduction, an enhanced warp-based reduction on the shared memory are presented to form partial results. Thirdly, for the configuration of the number of thread blocks, the number of thread blocks can be obtained by maximizing the size of thread block and the maximum size of threads per stream multi-processor on GPU. Finally, the proposed method is evaluated on three generations of NVIDIA GPUs with the better performances than previous methods.

Can Computerized Hounsfield Unit Estimation Be Used as Predictor for Ureteric Stone Localization by Fluoroscopy during Extra Corporal Shock Wave Lithotripsy and Ureteroscopy?

Current minimally invasive interventions for ureteric stones involve either ESWL or Ureteroscopy and stone localization is mandatory for successful treatment in both. Objectives: To avoid doing KUB radiograph before ESWL routinely by correlating the stone attenuation value on CT KUB with stone visualization at fluoroscopy. Methods: This is a prospective cross sectional hospital based, Multicentric study carried out on 1010 patients with ureteric stones in Sudan from August 2014 to March 2016. Results: Mean stone density in HU was 704.45 ± 300 (SD) ranging (81 - 1873) HU. All of the stones were localized using fluoroscopy and only 26.5% of them were not seen under fluoroscopy. I.V contrast was used mostly, and also mainly in the upper ureter. More than 80% of the application of contrast through the ureteric catheter was in the lower ureteric stones. 91.2% of patients with stone density ≤ 400 HU failed to appear at fluoroscopy and therefore 400 HU attenuation value can be used as a cut-off level to request doing KUB before ESWL and Ureteroscopy. Conclusion: the ureteric stones with density ≤400 HU the likelihood of being non-visualized at fluoroscopy is 91.2% therefore if the stone has ≤400 HU at CT KUB it is mandatory to do KUB before treatment above that it is most likely to be seen at fluoroscopy and no need to request KUB for them before ESWL or URS. 1) Inclusion Criteria: All patients diagnosed by CT scan to have ureteric stones for ESWL or Ureteroscopy. 2) Exclusion Criteria: Patients for whom treatment of ureteric stone by ESWL or ureteroscopy is not indicated like severe infection or poor kidney function where nephrectomy is needed.

Factors Promoting and Hindering Performance of Unit Nurse Managers at Kamuzu and Queen Elizabeth Central Hospitals in Malawi

Unit nurse managers in Malawi experience many challenges in the course of performing their roles. This affects their performance and service delivery including the quality of nursing care to patients. This study was conducted to determine the factors that hindered performance of unit managers in relation to expected quality of nursing services at two referral facilities (Kamuzu and Queen Elizabeth Central hospitals) in Malawi. These two central hospitals have the same structural settings and both offer specialized tertiary health services. A quantitative descriptive design was used to guide the planning and implementation of the study. Purposive sampling was used to select the two major hospitals in Malawi and all available 37 unit nurse managers during the time of the study at the two hospitals participated in the study. Data were collected using semi-structured questionnaires after seeking consent from the participants and were analyzed using SPSS version 16.0. The major roles identified by the unit managers were supervision (75.6%, n = 28) and coordination (70.3%, n = 26). Other roles such as team leader, liaison officer, research allocator, monitor and facilitator were rated by very few participants. Findings of the study showed that performance of unit nurse managers was affected by inadequate material (86.4%, n = 32) and human resources (94.5%, n = 35) and lack of managerial skills (5.4%, n = 2). In addition, the unit managers perceived their role to be stressful (38.9%, n = 14) and challenging (47.2%, n = 17). Therefore, there is a need to provide adequate material and human resources to the wards of the two central hospitals to enable the unit managers perform their duties efficiently.

Hierarchy of mesenchymal stem cells: Comparison of multipotentmesenchymal stromal cells with fibroblast colony forming units

The organization of the compartment of mesenchymal stem cells is still obscure. Two types of human stromal precursor cells are known. Both of them are analyzed in in vitro system: mesenchymal multipotent stromal cells (MMSC) and fibroblast colony forming units (CFU-F). The aim of this study was to compare the main characteristics of MMSC and CFU-F derived from the bone marrow of 24 healthy donors. Growth and differentiation parameters, as well as relative expression levels of different genes were analyzed in MMSC and CFU-F. MMSC were cultivated for 5 passages. CFU-F concentration was determined for each bone marrow sample. The data obtained demonstrated the heterogeneity and hierarchical organization of both studied populations of stromal precursor cells-MMSC and CFU-F. These two types of stromal precursor cells turned to be different in most parameters studied. Altogether MMSC seemed to be more immature cells than CFU-F and took up the higher position in hierarchical tree of mesenchymal stem cells. The rate of differentiation and proliferative potential decreased with the donor’s age in both populations MMSC and CFU-F.

县域尺度地球关键带分类框架与实证——以河南省西峡县为例

地球关键带分类有助于认知关键带的空间布局,了解其发生和演化的区域差异性,并可以作为观测和调查关键带的基础。为了延续大尺度地球关键带分类,在分析关键带组成要素的基础上,采用多层级划分法构建了一套小尺度关键带分类的框架,并在GIS中以图层叠置法对河南省西峡县做了实证研究。建立了一套涵盖分类原则、分类指标的多层级地球关键带分类框架,并将西峡县地球关键带划分为28个一级类型单元,246个二级类型单元和722个三级类型单元。这种划分可以提高对地球系统科学的整体认知,对小尺度地球关键带的科学研究和自然资源综合管理也具有一定的参考意义。

基于“等级-网络”双维度下的福建省县级单元对外服务能力空间格局演化

基于城市流强度模型和改进的引力模型,从“等级-网络”双维度下的对外服务能力空间关系,开展福建省县级单元对外服务能力格局演变的分析。结果表明:(1)第二、三产业对外服务能力均持续增强的同时,工业与商务商贸成为职能部门的“双子星”。(2)对外服务能力空间格局整体表现出沿海高于内陆的特征,各职能分工定位与发展态势逐步明晰。(3)对外服务能力网络格局中第二、三产业勾勒出以沿海高等级联系为主导并向内陆辐射延展的放射状网络;工业职能部门在内陆与沿海分别形成倒“T”型与“钻石型”主干网络。

一种十表冗余激光陀螺捷联惯组标定方法研究

针对十表冗余激光陀螺三自捷联惯组(包含5只陀螺和5只加速度计)的标定问题,推导给出了标定模型以及标定方案。将十表冗余惯组划分为直表X\Y\Z和斜表S\T两组,直表采用系统级标定方法,建立关于标定误差模型的状态方程,以导航速度误差作为量测,通过Kalman滤波估计标定误差参数;以直表标定结果作为参考,进行斜表的分立式标定,分别建立了加速度计、陀螺标度系数和陀螺漂移的标定模型。最后,结合19位置系统级标定方法和分立式标定方法完成了十表冗余激光捷联惯组标定,结果显示标定结果正确,分析了标定误差特性。

藏区重症监护病房首例耐碳青霉烯类鲍曼不动杆菌感染患者相关环境污染及患者感染情况

目的 调查藏区某院新建重症监护病房(ICU)中首例耐碳青霉烯类鲍曼不动杆菌(CRAB)感染患者相关环境污染及患者感染情况,分析传播风险。方法 从2021年11月15日检出的首例CRAB患者入住ICU开始至第60天期间,对入住ICU>48 h的所有患者进行CRAB主动筛查;在首例CRAB感染患者入住ICU第30天高频开展诊疗活动2 h后未消毒前、第60天消毒后未开展医疗活动前的环境分别采样,CRAB显色培养基培养。结果 主动筛查的13例患者中1例CRAB阳性,该病例于11月19日由三级医院ICU转入该院ICU,入住ICU第40天出现发热、吸痰需求增加并检出CRAB,药敏谱与首例病例相似,且安置于首例病例邻床。采样环境标本64份,CRAB阳性9份,阳性率14.06%,其中高频诊疗活动后洗手池、门把手、床栏等8个采样位点CRAB阳性,常规消毒后洗手池水槽检出CRAB。结论 在民族地区基层ICU CRAB防控工作中,对入科患者进行风险评估,高风险患者入科即采取集束化防控措施是可行的;应重点关注洗手池、门把手、床栏等区域污染及洗手池水槽消毒的有效性。

基于电池模块重构的储能电池异常两级诊断方法

准确监测储能电池衰减异常是保障电池储能系统安全运行的关键。采用可重构电池拓扑结构是未来电池储能系统的一大趋势,而现有的基于数据驱动的电池健康状态评估方法多关注算法层面的改进,难以利用这一结构的优势。针对这一问题,提出一种异常电池两级诊断方法:初级诊断采用通过全工况全寿命周期模拟数据集训练的最小二乘支持向量机分类模型,筛选出疑似异常电池模块;二级诊断采用一种基于残差连接和门控循环单元的健康状态估算模型,实现对储能电池健康状态的准确估计,并验证初级诊断结果。试验结果表明,提出的诊断方法在两个诊断环节上均具有较高的准确率,在可重构电池拓扑结构基础上实现了储能电池衰减异常的准确监测。

铝带连续退火机组设计与关键设备配置

文章结合某2350 mm铝带连续退火机组,对铝带连续退火机组的主要工艺参数、机组设备组成、关键设备要点等进行论述,以达到合理方案配置。

我国国家公园建设研究进展

中国国家公园是指在具有显著自然生态价值、文化价值和科学研究价值的区域内,通过完善自然保护与利用体系,实现保护物种、维护生态系统完整性、保障基本生态需求、实现可持续利用等目的,逐步形成具有国际水平的大型自然保护地并发挥其积极作用的区域。中国国家公园建设是实践生态文明思想的有效途径,是中国自然保护地体系建设最重要的组成部分。自2015年发布《建立国家公园体制试点方案》以来,中国政府陆续开展了10个国家公园体制试点,最终在2021年正式建立了5个国家公园。收集了2015年以来国家公园相关政策资料,对中国国家公园建设现状进行深入分析。我们发现中国国家公园较好的实现了初始建设目标,但也有需要完善的地方。针对未来国家公园的建设,我们提出了以下建议:1)完善国家公园空间布局规划;2)以流域为单元进行规划整合;3)确定东部和西部国家公园最小面积;4)确定国家公园数量上限;5)建立跨境国家公园;6)将文化保护纳入国家公园;7)统一管理体制;8)统一国家公园内部管控区划;9)形成三类保护地差异化可持续发展模式。未来随着中国国家公园顶层设计的逐步完善,中国自然保护地体系体制建设将能提供更加全面、系统的生态保护和资源管理,推动生态文明建设的不断发展;实现生态保护、可持续利用和人与自然的和谐共生的目标。

燃煤机组管道吊架位移稳定性评价

管道的膨胀位移特性影响燃煤机组安全性。基于在线监控数据对某超超临界机组管道吊架位移变化情况进行分析评价,构建稳定性评价函数对不同运行阶段的管道吊架位移进行评价。结果表明:管道吊架冷态停炉时位移量维持在冷态设计值左右。热态运行时位移量在热态设计值附近波动。机组启动过程,吊架位移量快速达到热态设计值附近。并网前子阶段吊架的膨胀位移程度比并网后子阶段更大。停机过程吊架位移变化集中在冷却子阶段。热态运行阶段热再蒸汽管道吊架位移稳定性最好,冷再蒸汽管道吊架位移波动最大,稳定性得分比热再管道吊架降低21.8%。机组启动过程各管道吊架位移变化稳定性基本相同。停机过程冷再蒸汽管道吊架位移变化最平稳,主蒸汽管道吊架位移变化相对剧烈,稳定性得分比冷再蒸汽管道吊架降低17.2%。构建的评价函数能准确表述管道吊架膨胀位移特性,为机组安全提供数据支持。

基于双通道数据主振动特征提取的水电机组轴系故障诊断

相对于特征层和决策层融合,数据层融合可以充分保留数据中的原始诊断信息,从而为后续故障诊断奠定基础。为此,提出一种基于双通道数据主振动特征提取的水电机组轴系故障诊断方法。该方法首先利用主成分分析(Principal Component Analysis,PCA)对轴系双通道时域振动信号进行数据层融合,得到最大振动强度方向上的合成振动(简称主振动);随后,对主振动进行特征提取,再利用支持向量机(Support Vector Machine,SVM)进行分类,从而实现故障诊断。利用转子台数据对所提方法进行验证。结果表明,与直接利用单通道进行诊断或通过双通道进行特征层融合诊断相比,所提方法可以消除主振动方向变化带来的影响,提升类内聚类和类间分离的效果,最终提高故障诊断的准确率。

水库水位的VMD-CNN-GRU混合预测模型

水库水位预测为其运营、防洪、水资源调度管理提供了重要决策支持.准确可靠的预测对水资源的优化管理起着至关重要的作用.针对水库水位数据的非线性、不稳定性以及复杂的时空特性,提出一种融合自适应变分模态分解(VMD)、卷积神经网络(CNN)和门控循环单元(GRU)的混合水库水位预测模型.VMD通过对水位序列进行分解消除噪声,CNN用于有效提取水位数据的局部特征,GRU用于提取水位数据的深层时间特征.以葠窝水库日水位为例,与多个相关模型对比分析,结果表明:精度方面,新模型在选取的评价指标上均表现最佳;运算效率方面,本文选择的GRU与长短时记忆网络(LSTM)相比,运算效率显著提高.新模型预测的高精度、高运算效率更能满足实际水库水位实时调度的需求.

智能型大功率双向三电平DC/DC变换器研制

此处首先从轨道交通装备“绿色、节能、环保”的技术需求出发,说明了设计大功率双向三电平变换器的必要性,并点出三电平相对于两电平拓扑的技术优越性;然后详细阐述了双向三电平DC/DC变换器的工作原理,并通过理论公式计算对200kW工程样机的关键部件进行选型;然后采用Matlab仿真软件搭建系统模型进行仿真,最后通过联调试验,证明了仿真波形与实测波形基本吻合,验证了双向三电平DC/DC变换器理论分析及计算的正确性。