A brief discussion on the relationship between apparent stress and slip-weakening law based on the energy partition criteria

According to the representation theorem of seismic energy radiation, we know that, at any point on the fault, the instantaneous seismic radiation energy, Es, the seismic moment M0, and the apparent stress σa=μEs /M0 （μ is the shear modulus on the fault plane） should be positive values at any time during an earthquake faulting. However, we have noticed that, in recent source parameter inversion scheme for deriving the critical slip-weakening distance, the apparent stress used as a constraint condition on the fault plane could be less than zero or negative value, and the negative part was considered as dissipation energy and incorporated to the fracture energy. Although the mathematical formula in such case has no influence to the final resolution, however, the earthquake dynamic source process violates obviously the basic physical law, which could results in the overestimating of radiated seismic energy. In this study, we have proposed an alternative way to take account of the apparent stress expression based on the earthquake energy partition principle, and at the same time, we have also suggested that an additional constraint regarding to the radiation energy conservation on the fault could be added into the source parameter inversion in order to estimate the critical slip-weakening distance Dc.

Radiation exposure and reduction in the operating room: Perspectives and future directions in spine surgery

Intraoperative imaging is vital for accurate placement of instrumentation in spine surgery. However, the use of biplanar fluoroscopy and other intraoperative imaging modalities is associated with the risk of significant radiation exposure in the patient, surgeon, and surgical staff. Radiation exposure in the form of ionizing radiation can lead to cellular damage via the induction of DNA lesions and the production of reactive oxygen species. These effects often result in cell death or genomic instability, leading to various radiation-associated pathologies including an increased risk of malignancy. In attempts to reduce radiation-associated health risks, radiation safety has become an important topic in the medical field. All practitioners, regardless of practice setting, can practice radiation safety techniques including shielding and distance to reduce radiation exposure. Additionally, optimization of fluoroscopic settings and techniques can be used as an effective method of radiation dose reduction. New imaging modalities and spinal navigation systems have also been developed in an effort to replace conventional fluoroscopy and reduce radiation doses. These modalities include Isocentric Three-Dimensional C-Arms, O-Arms, and intraoperative magnetic resonance imaging. While this influx of new technology has advanced radiation safety within the field of spine surgery, more work is still required to overcome specific limitations involving increased costs and inadequate training.

Static and Dynamic Components of the Redshift

We analyse the possibility that the observed cosmological redshift may be cumulatively due to the expansion of the universe and the tired light phenomenon. Since the source of both the redshifts is the same, they both independently relate to the same proper distance of the light source. Using this approach we have developed a hybrid model combining the Einstein de Sitter model and the tired light model that yields a slightly better fit to Supernovae Ia redshift data using one parameter than the standard ΛCDM model with two parameters. We have shown that the ratio of tired light component to the Einstein de Sitter component of redshift has evolved from 2.5 in the past, corresponding to redshift 1000, to its present value of 1.5. The hybrid model yields Hubble constant H0 =69.11(±0.53)km·s-1 ·Mpc-1 and the deceleration parameter q0 =-0.4. The component of Hubble constant responsible for expansion of the universe is 40% of H0 and for the tired light is 60% of H0. Consequently, the critical density is only 16% of its currently accepted value;a lot less dark matter is needed to make up the critical density. In addition, the best data fit yields the cosmological constant density parameter =0. The tired light effect may thus be considered equivalent to the cosmological constant in the hybrid model.

NOISE OF THE RING SPINNING FRAME AND ITS CONTROL

In this paper, we have made a study on the noise of ring spinning frame by analysing the noise radiating mechanism and the frequency spectrum of its main noise sources, such as the spindle system and the transmission gear trains of the ring frame. Finally, three measures for reducing its noise are suggested: (1) using upper elastic bearing for the spindle structure, (2) using vibration isolating washers for the spindle support, and (3) improving the gear transmission structure design in the headstock of the frame.

The Influences of an Embedded Structure Fiber-Optic Radiation Dosimeter in Different SSD and Beam Field Size

With a rapidly increasing demand and widespread use of radiotherapy treatment, the subject area of in-vivo real time dose rate dosimeters has become a significant area of study. An embedded structure fiber-optic radiation dosimeter has proved to be a promising candidate to fulfil this role because of its high SNR (signal-to-noise ratio) and excellent light conversion efficiency. In this paper, the properties of this kind of dosimeter with respect to different SSD (Source to Surface Distance) and beam field size in a clinical Linac are studied. The characteristics of the dosimeter were evaluated by the sensor’s output intensity response in these conditions.

Combination of Metal Shielding and Distance Estimation for Electromagnetic Compatibility Guarantee

In this paper, a solution for electromagnetic compatibility guarantee based on the combination of metal shielding and circuit components distance estimation methods is presented. The electromagnetic noises generated from a working radio-electronic unit can expand into the space and act on other around radio-electronic units. An EMC guaranteed radio-electronic unit by the suitable technique method will not cause the electromagnetic noise to others. In opposition, it will not be under electromagnetic action from another one. Due to the power of electromagnetic noise, the metal shielding, distance estimation or other technique methods should be used to guarantee EMC. Every method has own advantage as so as weakness for detail radio-electronic unit, so it is necessary to choose a suitable method to guarantee EMC for them, the combination of metal shielding and distance estimation is a choice, for example. The proposed solution has been evaluated by using CST (Computer Simulation Technology) software and EMxpertEHX analyzer in oscillator circuit context. The simulated results on CST show that the proposed solution decreases the electromagnetic radiation about of 39.1 dB at frequency 500 MHz in comparison to results when nothing electromagnetic compatibility methods are not used. The experimental results on the oscillator circuit are presented. The electromagnetic radiation reduction of the oscillator circuit is about of (25 - 30) dB. In comparison to individual metal shielding and distance estimation methods, the effectiveness of the proposed solution for electromagnetic compatibility guarantee is significantly increased.

Three influencing factors on the level of non-ionizing radiation

The role of three factors on the level of non- ionizing radiation is treated in this project: that of 1) the distance of the exposed body from the source, 2) the power of the source device and 3) the frequency of the source. The important factor of time, as well as other factors, are not at all ignored in this manuscript. In this work I emphasise the rules of the relationship with this necessary contaminant, and that exposures towards it should be avoided as far as possible.

风扇与辐射空调耦合系统的热舒适分析

针对顶板辐射供冷系统存在的噪声问题,提出了一种采用辐射供冷与吸音板耦合系统,同时,通过在辐射顶板和吸音板之间增加风扇(向下吹),来抵消由于吸音板导致的辐射热交换的减少。重点研究了顶板辐射供冷与风扇耦合系统的室内气流分布、热舒适以及传热系数变化,其影响因素包括:吸音板覆盖率、风扇转速、房间高度。结果表明:风扇的加入增强了顶板的对流换热和总换热;随着风扇转速的增加和吸音板覆盖率的降低,室内空气温度降低;与无风扇的顶板辐射系统相比,风扇在高转速工况下的PMV值降低了0.37~0.40,总传热系数增长了28.4%~45.4%,在吸音板覆盖率为16%时,总传热系数的增长率达到峰值;可以通过增加风扇从而强化室内空气流动的方式来补偿较高室温带来的不适感。研究结果为顶板辐射系统的实施提供了有前景和实用的设计方案。

叉车发动机舱散热特性及空间布局优化仿真研究

叉车速度较低且发动机舱内部复杂,在叉车研发设计阶段,如何提高发动机舱散热能力,优化散热器性能已成为工程师关注的焦点。以某型号叉车发动机舱的散热特性为研究对象,建立了叉车发动机舱的实体模型,利用计算流体动力学方法,分析了发动机舱内温度场和流场。研究了风扇竖直方向位置、风扇相对聚风罩轴向嵌入度、风扇与散热器距离这3个关键因素对发动机舱散热性能的影响规律。利用多指标分析综合平衡法进行正交试验分析,获得了散热机舱内空间布局的最优方案,即上移风扇10 mm、风扇轴向嵌入度60%、风扇与散热器距离增加20 mm。该优化方案可以使水散热器散热量提高11.76%,液压油散热器散热量提高7.16%。

红外系统对战机的探测性能仿真分析

通过新建战机尾焰的红外辐射椭圆体模型,改进了战机红外辐射的计算方法,并得到了战机在3~5μm波段红外辐射的空间分布曲线。通过对该曲线的分析,发现该战机的红外辐射在机尾和机头各有4个辐射强度相同的极值方向。考虑到臭氧在3~5μm波段内的吸收、地面遮挡红外辐射传输和探测大气层外目标等因素,引入红外辐射大气传输距离概念进一步完善3~5μm波段红外辐射大气传输模型。以归一化探测度不同的2种红外探测器构建的红外系统为例,仿真得到战机的作用距离随探测方向变化的曲线。计算结果表明,红外系统对战机的作用距离极值并不在战机红外辐射极值方向上,且当系统作用距离较远时,大气衰减对作用距离的影响将超过战机红外辐射的影响。

基于椭球模型的FANS航线算法

为提高RNAV(区域导航)精度,采用空间向量分析,导出了FANS(国际民航组织倡导的新航行系统)航线的初始航线角和航线距离计算公式;用辛普森自适应算法进行了仿真计算,并与大圆航线的计算结果进行了比较.结果表明,当航程小于1 000 km时,对于近EW走向的航线,FANS航线比大圆航线长约0.35%;而对于近SN走向的航线,FANS航线比大圆航线短约0.24%.

不同空调模式下负压病房内污染物分布特性研究

针对分体空调器、风机盘管都存在室内空气循环流动、冷凝水聚集等问题,本研究通过CFD软件对负压病房进行模拟,对比分析了辐射空调系统和风机盘管系统在负压病房应用时室内热湿环境、污染物分布特性和医护人员感染风险,并建立了全尺寸辐射空调负压病房实验室并对结果进行了验证。结果表明:采用辐射空调系统不仅能够降低室内垂直温差,减少吹风感,而且能够降低室内污染物浓度和室内人员感染风险;辐射空调与风机盘管相比室内污染物浓度、暴露风险和感染概率最大降幅分别为29.85%,29.27%和15.79%。研究结果可为负压病房的设计和医护人员感染风险评估提供参考。

不同散热器结构对其散热特性影响的数值研究

本文采用Flotherm热仿真软件,分别研究了翅片布局、散热器参数变化以及布置风机对散热器散热特性的影响。研究表明:①芯片节点温度Tj随空气流速Uc的提高而逐渐降低。相比于翅片沿散热器长度方向布置,翅片沿散热器宽度方向布置更优,散热器散热性能更好,芯片节点温度更低,但是随着空气流速逐渐升高时,这种优势逐渐降低。②当基板和翅片总高度一定时,存在一组最优的基板高度和翅片高度,使得散热器的散热性能最优,芯片节点温度最小。③当空气流速较低时,相比于散热器(不带风机),散热器(带风机)可明显降低芯片节点温度,节点温度降幅Tj%随空气流速Uc的提高而减小。当空气流速增大一定程度时,节点温度降幅Tj%为负值,即散热器(带风机)散热性能更差,芯片节点温度反而更高。

收获机械发动机冷却变向风扇开发与应用

收获机械作业时发动机转速高,在发动机冷却风扇作用下秸杆及杂草堆积在散热器前阻碍空气流通,导致散热性能差,针对这种问题开发了变向风扇,通过液压系统控制冷却风扇扇叶角度,使风扇在吸风及吹风间转换,从而有效地自动清除散热器吸附的杂物,达到散热系统自清洁的目的。经试验,变向风扇性能满足热平衡要求,可靠性满足1000 h无故障的要求,风扇本体噪声恶化1.78%满足NVH要求。

超长距离掘进巷道通风安全保障技术研究

为了确保超长距离巷道掘进通风系统平稳运行,以31采区支架专用运输巷掘进通风为例,通过计算工作面用风量并考虑长距离通风时风筒漏风情况,综合选择了大功率局部风机,实施了变频通风和柔性风筒将阻措施,并制定了长距离通风安全保障措施。实践表明,31采区支架专用运输巷掘进工作面通风稳定,供风量在592 m~3/min左右,风速在0.33 m/s左右,风量和风速始终在合理范围内,充分保障了工作面良好的工作环境。

采用AC0.69k V为市域线远距离低压电动机配电的应用研究

分析了市域线区间内电动机负荷采用AC 0.69 kV(660 V)供电的可行性与经济性。AC 0.69 k V(660 V)为规范规定的标准电压,低压相关元器件均可在0.69 kV系统中正常运行,其实际运用案例在我国工业领域已数不胜数。研究表明,AC 0.69 kV应用于市域线电动机配电领域是可行的;可选择合适的负荷,由AC 0.69 kV供电,其他负荷的配电方案可按常规的AC 0.4 kV方式供电,2种方案可并行;各市域线项目应根据工程投资估算确定远距离电机配电方案。当负荷的距离及容量合理时,AC 0.69 kV可显著减少工程的总投资。

Radiator Heat Dissipation Performance

This paper presents a set of parametric studies of heat dissipation performed on automotive radiators. The work’s first step consists of designing five radiators with different fin pitch wave distance (P = 2.5, 2.4, 2.3, 2.2, 2.1 mm). Then, we proceed to the fabrication of our five samples. The purpose of this work is to determine through our experiment’s results which one have the best cooling performance. This numerical tool has been previously verified and validated using a wide experimental data bank. The analysis focuses on the cooling performance for automobile radiator by changing several dimensions of the radiator fin phase as well as the importance of coolant flow lay-out on the radiator global performance. This experience has been performed at Hubei Radiatech Auto Cooling System Co., Ltd. For the cooling performance experience, we use JB2293-1978 Wind Tunnel Test Method for Automobile and Tractor Radiators. The test bench system is a continuous air suction type wind tunnel;collection and control of operating condition parameters can be done automatically by the computer via the preset program, and also can be done by the user manually. The results show that the more we increase the fin phase, the better the cooling performance will be and we also save material so the product cost will be cheaper.

COVID-19 and information and communication technology in radiation oncology:A new paradigm

Due to coronavirus disease 2019 pandemic caused by severe acute respiratory syndrome coronavirus 2,there has been a major reallocation of resources that has impacted the treatment of many diseases,including cancer.The growing use of information and communication technologies(ICT),together with a new approach to work aimed at ensuring the safety of health care professionals and patients alike,has allowed us to maintain the quality of care while ensuring biosecurity.The application of ICT to health care(eHealth)aims to significantly improve the quality,access to,and effectiveness of medical care.In fact,the expanded use of ICT has been recognized as a key,cost-effective priority for health care by the World Health Organisation.The medical speciality of radiation oncology is closely linked to technology and as a consequence of coronavirus disease 2019,ICT has been widely employed by radiation oncologists worldwide,providing new opportunities for interaction among professionals,including telemedicine and e-learning,while also minimizing treatment interruptions.Future research should concentrate on this emerging paradigm,which offers new opportunities,including faster and more diverse exchange of scientific knowledge,organizational improvements,and more efficient workflows.Moreover,these efficiencies will allow professionals to dedicate more time to patient care,with a better work-life balance.In the present editorial,we discuss the opportunities provided by these digital tools,as well as barriers to theirimplementation,and a vision of the future.

天然气管道全管径断裂喷射火对周边建筑物外立面热辐射分布研究

为了评价天然气全管径断裂喷射火的风险,采用CFD软件Flacs模拟天然气管道全管径断裂喷射火过程,分析了不同工况下的危险区、轻伤区距离与距泄漏点不同距离处外立面热辐射强度分布。结果表明,在管道周边给定的位置,建筑物外立面所承受热辐射强度要高于地面处。当泄漏速率为8 253 kg/s时,在距泄漏点200 m处的外立面上,20 m高度处热辐射强度为46 kW/m^(2),比15 m高度处高3 kW/m^(2),比10 m高度处高8 kW/m^(2),比5 m高度处高13 kW/m^(2),比地面处高18 kW/m^(2)。因此,仅以地面处热辐射强度作为安全距离的选择标准可能会导致高楼内的居民遭受伤害。根据CFD软件模拟结果,拟合了建筑物不同高度处的热辐射随管道距离的变化关系,或可为管道线路规划提供参考。与经验模型对比结果表明,点源模型可以较保守地用于分析天然气管道对周边建筑物的喷射火热辐射危害距离。

碘-125植入术后病区护理人员外周血象监测及防护

目的探讨碘-125植入术后放射暴露对病区护理人员血象影响,为改善护理人员放射防护提供依据。方法以接触碘-125植入术后的病区护理人员为实验组进行外周血象监测,与同一时期内无粒子植入病区护理人员(对照组)血象结果进行比较分析;另对碘-125植入术后患者当天在有铅衣覆盖和无铅衣覆盖的情况下,分别从不同角度和距离进行γ射线测得结果进行比较分析。结果外周血象指标结果显示实验组低于对照组,但差异无统计学意义(P>0.05);无铅衣覆盖的情况下,距离手术穿刺点100 cm测得放射剂量(10.6±2.6)uSv/h接近γ射线测量天然本底剂量,有铅衣覆盖情况下,距离15 cm测得放射剂量(10.4±2.0)uSv/h接近γ射线测量天然本底剂量。结论采用铅衣防护后,碘-125植入后放射暴露对病区护理人员外周血象无明显影响,能有效缩短安全放射距离。