基于SoC的DW450断路器用欠压脱扣器研究与设计

针对新一代智能型低压万能式DW450断路器体积明显缩小,且对内嵌电子单元要求更高等特点,设计一种基于SoC(system-on-chip)的高性能欠压脱扣器。在现有DW45电磁型欠压脱扣器的基础上,分析存在的问题,提出基于电容降压、电容充放电的新方案。实验表明:该欠压脱扣器方案整体电路简洁,在78mm×30mm×35mm的空间里实现瞬时或延时欠压脱扣;动作点准确度达±2V,测控电路工作电流仅为0.73mA@5V。为新一代智能型低压万能式DW450断路器提供一种高可靠的小型化欠压脱扣器优选方案。     

舰船设备抗冲击能力的可靠性分析

在进行舰船设备系统抗冲击设计及优化分析中,必须要确定舰船设备的抗冲击能力值,而影响设备冲击响应的多种随机因素使设备抗冲击能力具有随机性。本文提出了考虑各种随机因素影响的设备抗冲击能力可靠性的定义和分析方法,结合神经网络建立了设备冲击响应预测模型,在数值冲击试验基础上,结合Monte Carlo法分析了典型舰船设备抗冲击能力的统计特征。分析方法和结果可为今后舰船设备及系统的抗冲击性能分析、舰船系统抗冲击性能评估提供参考。     

舰艇导弹发射装置抗冲击性能数值分析

舰船设备抗冲击性能是评价舰艇生命力的重要因素之一。分别应用美国海军用以考核舰船设备抗冲击性能的动态设计分析方法(DDAM)和时间历程法,考核舰船甲板设备四联装导弹发射装置的抗冲击性能。通过DDAM方法和时间历程方法仿真计算,得到导弹发射装置的抗冲击薄弱环节,为制定导弹发射装置抗冲击考核标准提供参考。     

舰艇导弹发射装置抗冲击性能数值分析

舰船设备抗冲击性能是评价舰艇生命力的重要因素之一。分别应用美国海军用以考核舰船设备抗冲击性能的动态设计分析方法(DDAM)和时间历程法,考核舰船甲板设备四联装导弹发射装置的抗冲击性能。通过DDAM方法和时间历程方法仿真计算,得到导弹发射装置的抗冲击薄弱环节,为制定导弹发射装置抗冲击考核标准提供参考。     

浅谈低压断路器在建筑配电系统中的应用

低压断路器在建筑低压配电系统中被广泛使用，是一种保护电器元件。在设计低压配电系统时，应注意低压断路器的选择性和级联保护性：对低压断路器过流脱扣器额定电流进行选择和整定，确保过电流脱扣器动作的灵敏度；当环境温度大于或小于校准温度值时，应根据制造商提供的温度与栽流能力修正系数来调整低压断路器的额定电流值。     

建筑配电系统中低压断路器的选用

低压断路器具有断路保护、过载保护、控制和隔离的功能,广泛应用于工业与民用建筑终端的低压配电系统。低压断路器在低压配电系统中若设计不当,就会影响整个供电系统的正常运行。笔者借此谈一下低压断路器在低压配电系统设计中应注意的问题。在低压配电系统的设计中,要注意低压断路器的选择性和级联保护性,对低压断路器脱扣器额定电流进行选择和整定,保证电流脱扣器动作的灵敏度,当环境温度变化与校准温度值不一致时,要根据制造商提供的温度与载流能力来修正系数,调整低压断路器的额定电流。简要介绍了在建筑低压配电系统中断路器选择的方法。     

船用典型动力设备抗冲击性能评估研究

介绍了舰船设备抗冲击计算的动态设计计算法(DDAM)和时域模拟法,根据舰船动力机组各组成设备的结构特点,分别采用DDAM方法和时域加载法在频域和时域上对其进行抗冲击计算分析.计算分析结果表明,不同设备对冲击载荷的响应与设备本身的结构特点有关,且与冲击加载方向有很大关系.对于主汽轮机组和主减速齿轮装置,由于各个构件之间存在连接关系,螺栓、销钉及其连接结构的动态响应更为敏感.所得分析结论可以对开展舰船设备抗冲击计算分析以及新型舰船设备的抗冲击设计提供一定的参考.     

舰载电子设备抗冲击设计概要

舰载电子设备是舰船信息化建设的基础,在实际工作环境中,不可避免地会受到水下爆炸冲击作用,如果结构设计不当,将使其受到损害以至失效。从舰船冲击环境和电子设备的抗冲击要求出发,概要性地提出舰载电子设备抗冲击设计的基本原则,指出在电子机柜设计、冲击下工程材料的动态特性及采用隔振器进行抗冲击防护设计三方面的要点,并对采用冲击试验机对舰载电子设备抗冲击能力进行考核时冲击试验机的选择和相关冲击标准进行介绍。     

水下非接触爆炸抗冲击缓冲平台性能研究

为有效测量水下非接触爆炸试验中舰船及设备的抗冲击性能,保护测量设备在冲击环境下能够安全使用,根据设备冲击输入设计和研制了抗冲击缓冲平台,以减小舰船设备在水下非接触爆炸冲击作用下受到的冲击.按照要求的缓冲平台设计载荷和缓冲效率,进行缓冲器刚度的选择和结构设计,利用仿真运算设计工况.经海上实爆冲击试验验证,该缓冲平台能有效...     

抗冲击瓦结构舰船毁伤效能评估研究

针对舰船毁伤效能评估问题,进行了抗冲击瓦结构舰船毁伤效能评估方法研究。研究结果显示,炸药爆炸威力及目标易损性构成了不可偏废型舰船毁伤效能评价指标体系,爆炸威力赋值可通过炸药TNT当量及舰船排水量计算得出,抗冲击瓦抗毁伤性能评估值可采用灰色层次分析法计算,采用文中给出的毁伤效能计算方法能够实现抗冲击瓦结构舰船毁伤效能的量化评估。     

基于近场静电纺丝的微／纳米结构直写技术

基于近场静电纺丝（舾）,研究了可用于柔性电子制造的微／纳米结构直写技术．构建了电极、收集板可协调运动的直写实验平台,分析了电纺丝参数对微／纳米结构直写过程的影响和直写参数间的匹配．通过缩短电纺丝距离实现对直写过程的控制,分别采用直径为25μm的实心探针针尖和内径为232μm的空心注射针尖作为电纺丝喷头,可有序地直写出直径为50—500nm的纳米纤维和线宽为1—8μm的微米结构．实验结果表明：微米结构线宽随收集板速度和PEO溶液浓度的变大而变大;直写工作电压随收集板运动速度的变大而减小,随电极至收集板距离的增加而变大．协调电极与收集板运动速度,平行直写微米结构间距可控制在100-180μm之间．     

高速铁路风障在横风与列车风耦合作用下的气动特性研究

针对单层、腔室型两种形式的开孔波纹板风障,采用滑移网格方法分别模拟横风条件下高速列车通过风障区域的过程,分析了在横风和列车风耦合作用下风障周围的绕流流场特性、风障面板气动荷载的时域特性及横风与列车风耦合脉动压力的频域特性。结果表明:在高速列车行经风障区域的过程中,无横风时头车产生的冲击作用要大于尾车的;存在横风作用时,列车头车产生的气动冲击作用与横风作用形成对冲,抵消了部分横风能量,而列车尾车则与横风作用相叠加,放大了横风对风障的气动作用;单层风障通过改变横风流向起到挡风减载作用,而腔室型风障同时可在腔室内部及尾流形成大量小漩涡来消耗横风能量,使用腔室风障能显著降低单个风障面板的气动荷载;该研究中,横风与列车风耦合作用于风障的脉动压力以及气动荷载的主频谱峰值集中在0.5~5 Hz内。     

Clinical praxis for assessment of dry weight in Sweden and Denmark: A mixed‐methods study

Overhydration is an independent predictor of mortality in hemodialysis (HD) patients. More than 30% of HD patients are overhydrated, motivating the development of new methods for assessing hydration status. This study surveyed clinical praxis and local guidelines for dry weight (DW) assessment in Swedish and Danish HD units, and examined if differences in routines and utilization of bioimpedance spectroscopy (BIS) and other assistive technology affected frequency of DW adjustments and blood pressure (BP) levels. Cross‐sectional information on praxis, guidelines and routines, plus treatment‐related data from 99 stratified patients were collected. Qualitative data were analyzed with content analysis and interpreted in convergence with statistical analysis of quantitative data in a mixed‐methods design. Local guidelines concerning DW existed in 54% of the units. A BIS device was present in 52%, but only half of those units used it regularly, and no correlations to frequency of DW adjustments or BP were found. HD nurses were authorized to adjust DW in 60% of the units; in these units, the frequency of DW adjustments was 1.6 times higher and systolic BP pre‐HD 8 mmHg lower. There is a wide variation in routines for DW determination, and there are indications that authorization of HD nurses to adjust DW may improve DW assessment. BIS is sparsely used; its implementation may have been delayed by uncertainty over how to manage the device and interpret measurements. Hence, better methods and guidelines for assessing DW and using BIS need to be developed.     

冷喷涂技术研究进展及其在舰船领域的应用

冷喷涂作为一种低温固态成型技术,具有基材热影响小、粉末材料不易氧化、沉积效率高等特点,可用于金属防护涂层制备、零部件修复和增材制造。首先从冷喷涂系统、喷涂材料、喷涂工艺3个方面介绍了冷喷涂技术的特点;其次总结了近年来冷喷涂技术在粉末材料设计、涂层结合机理、组织结构与性能调控方面的研究进展;然后,详述了冷喷涂技术在国外海军舰船领域的应用情况;最后,简述了冷喷涂技术在我国海军舰船领域的研究及应用情况,并对其未来发展方向进行了展望,以期提高我国海军舰船装备腐蚀防护及维修保障能力。     

新型重型卸料车的改进探讨

卸料车作为一种机械化自动卸料设备,该设备能自动的完成输送皮带机的中间卸料,具有连续卸料,指定点卸料等功能。本文从结构设计和控制两个方面对以往的卸料车进行改进创新,使其能够长期连续双向运行,安全可靠,起停平稳,定位准确,维护工作量小,使用寿命长且出力大。     

Oscillatory reduction of domain wall depinning field by transverse magnetic field in ferromagnetic permalloy nanowires

Reported herein is a possible way of controlling the depinning field of magnetic domain walls (DWs) by using a magnetic field H(T) transverse to the nanowire. A typical notch structure-in the form of triangles on both edges of ferromagnetic Permalloy nanowires-is employed to pin the DWs. The depinning field of the DW initially pinned at the notch is then measured with respect to H(T). Interestingly, it is experimentally found that the depinning field is drastically decreased to almost 0 with increasing H(T), due to the internal shift of the DW position at the notch. Moreover, it is experimentally observed that an oscillatory behavior of the depinning field occurs with respect to H(T), Micromagnetic calculation is performed to model the depinning behavior of the DW pinned at the notch structure with respect to H(T). It is ascribed to the natural edge roughness of the nanowire, which means the edge roughness plays an important role in determination of the depinning field.     

BOG冷能在LNG船上的综合利用研究

针对LNG船舶每日产生的低温蒸发气的冷能浪费问题,提出了通过利用氮气闭式循环气体透平技术和冷能的梯级利用,回收这部分原本被浪费的冷能来发电,这部分冷能还能用来供给冷库用以制冷,同时升高蒸发气的温度供给燃烧,可以起到提高经济性及合理利用能源的目的.该文将为冷能综合利用技术在LNG船上实际应用建立理论和技术基础.     

60万桶FPSO船体在十年一遇海况下的大幅运动模拟

简述了船舶在规则波中纵向大幅运动的计算方法,并将该方法推广到不规则波的运动计算中.基于切片理论的扩展方法,考虑由于船体的湿表面变化而产生的非线性因素,采用频域计算方法和时域计算方法相结合,线性处理和非线性修正相补充的方法,对水面船舶在不规则波中的纵向大幅运动进行计算.文中采用的谱分析技术,理论上讲不适用于船舶的大幅运动,但由于大量计算结果表明船舶纵向运动响应非线性不强,这就为我们的计算提供了基本条件,并以FPSO船体为例,运用C++语言编程实现船体在十年一遇海况下的大幅运动模拟,得到船舶运动六自由度的运动响应曲线.     

The influence of moving domain walls on the appearance of the second harmonic in the magnetoimpedance spectrum of a cobalt-based amorphous microwire

We have studied the influence of moving domain walls (DWs) on the magnetoimpedance of a cobalt-based amorphous microwire. A model describing the DW motion in the electric field of an alternating current in the absence of a skin effect is proposed. When the current amplitude exceeds a certain threshold value, the DW motion leads to the appearance of a second harmonic component in the frequency spectrum of the sample response voltage. The second harmonic amplitude has been studied as a function of the external longitudinal magnetic field, the current frequency, and the angle of deviation of the microwire anisotropy axis from the circular direction. The sensitivity of the second harmonic to the external magnetic field can be significantly higher than that of the first harmonic.     

A fresh look at dry weight

The concept of dry weight (DW) is central to dialysis therapy. The most commonly used definition of DW is the weight below which patients become hypotensive on dialysis. However, this definition is dependent on patient symptoms. A more rigorous definition of DW is the body weight at a physiological extracellular volume (ECV) state. Overhydration is an excess in ECV above that found in healthy subjects. In healthy subjects, within extremes of salt intake, ECV may vary between 280 and 340 mL/kg lean body mass. Sodium accumulation is one of the many consequences of renal failure; it results in increased water intake and an increase in ECV, and an accompanying rise in blood pressure with its clinical sequelae, most prominently cardiovascular and cerebrovascular diseases. Recently characterized endogenous digitalis‐like factors which are released in response to ECV expansion have extended this traditional picture. Efforts to reduce a positive sodium balance include dietary counseling and avoidance of iatrogenic intradialytic sodium loading, such as dialysate sodium exceeding serum levels, sodium profiling, and intravenous saline. Excess ECV is predominantly located in the interstitial compartment and must be removed during dialysis therapy by ultrafiltration. During this process, interstitial fluid redistributes to the intravascular space via uptake in the capillary bed. In addition to that mechanism, we propose that increased lymphatic flow into the venous system contributes to plasma refilling. Both clinical and technical means are used to assess the presence of DW. Continuous segmental calf bioimpedance is a promising new technology for intradialytic DW diagnosis.