Cone-shaped source characteristics and inductance effect of transient electromagnetic method

Small multi-turn coil devices are used with the transient electromagnetic method （TEM） in areas with limited space, particularly in underground environments such as coal mines roadways and engineering tunnels, and for detecting shallow geological targets in environmental and engineering fields. However, the equipment involved has strong mutual inductance coupling, which causes a lengthy turn-off time and a deep “blind zone”. This study proposes a new transmitter device with a conical-shape source and derives the radius formula of each coil and the mutual inductance coefficient of the cone. According to primary field characteristics, results of the two fields created, calculation of the conical-shaped source in a uniform medium using theoretical analysis, and a comparison of the inductance of the new device with that of the multi-turn coil, show that inductance of the multi-turn coil is nine times greater than that of the conical source with the same equivalent magnetic moment of 926.1 A·m2. This indicates that the new source leads to a much shallower “blind zone.” Furthermore, increasing the bottom radius and turn of the cone creates a larger mutual inductance but increasing the cone height results in a lower mutual inductance. Using the superposition principle, the primary and secondary magnetic fields for a conical source in a homogeneous medium are calculated; results indicate that the magnetic behavior of the cone is the same as that of the multi-turn coils, but the transient responses of the secondary field and the total field are more stronger than those of the multi-turn coils. To study the transient response characteristics using a cone-shaped source in a layered earth, a numerical filtering algorithm is then developed using the fast Hankel transform and the improved cosine transform, again using the superposition principle. During development, an average apparent resistivity inverted from the induced electromotive force using each coil is defined to represent the comprehensive resistivity of the conical source. To verify the forward calculation method, the transient responses of H type models and KH type models are calculated, and data are inverted using a “smoke ring” inversion. The results of inversion have good agreement with original models and show that the forward calculation method is effective. The results of this study provide an option for solving the problem of a deep “blind zone” and also provide a theoretical indicator for further research.

Improved HHT and its application in narrowband radar imaging for precession cone-shaped targets

Imaging the spatial precession cone-shaped targets with narrowband radar is a new technical approach in mid-course recognition problem. However, most existing time-frequency methods still have some inevitable deficiencies for extracting microDoppler information in practical applications, which leads to blurring of the image. A new narrowband radar imaging algorithm for the precession cone-shaped targets is proposed. The instantaneous frequency of each scattering point is gained by using the improved Hilbert-Huang transform, then the positions of scattering points in the parameter domain are reconstructed. Numerical simulation and experiment results confirm the effectiveness and high precision of the proposed algorithm.

Study of the Dynamic Characteristics of A Cone-Shaped Recovery System on Submarines for Recovering Autonomous Underwater Vehicle

National navies equip their submarines with Autonomous Underwater Vehicle(AUV)technology.It has become an important component of submarine development in technologically-advanced countries.Employing advanced and reliable recovery systems directly improves the safety and operational efficiency of submarines equipped with AUVs.In this paper,based on aerial refueling technology,a cone-shaped recovery system with two different guiding covers(closed structure and frame structure)is applied to the submarine.By taking the Suboff model as the research object,STAR-CCM was used to study the influence of the installation position of the recovery system,and the length of the rigid rod,on the Suboff model.It was found that when the recovery system is installed in the middle and rear of the Suboff model at the same velocity and the same length of the rigid rod,the Suboff model has the good stability and less drag.It experiences the largest drag when being installed in the front of the rigid rod.Moreover,when the recovery system is installed in the front and middle of the rigid rod,the drag increases as its length increases,and the lift decreases as its length increases.Compared with the closed structure guiding cover,the Suboff model will have less drag and better stability when the recovery system uses the frame structure guiding cover.Besides,the deflection and vibration of the rigid rod were also analyzed via mathematical theory.

Forging process modeling of cone-shaped posts

Using the rigid visco-plastic Finite Element Method (FEM), the process offorging for long cone-shaped posts made of aluminum alloys was modeled and the correspondingdistributions of the field variables were obtained based on considering aberrance of grids, dynamicboundary conditions, non-stable process, coupled thermo-mechanical behavior and other specialproblems. The difficulties in equipment selection and die analysis caused by the long cone shape ofpost, as well as by pressure calculation were solved.

Theoretical and experimental research on influence of rotor taper on performance of cone-shape helical pumps

The structure of a rotor has full impact on the performance of cone-shaped helical pumps. Numerical simulation and experimental tests are applied to get pressure, velocity and flow of a cone-shaped helical pump, and explores flow condition of blood in artificial blood pump. Rotors with four different tapers of artificial pump are designed. The flow condition of blood at the entrance, near the front diffuser, near the rotor, near the rear diffuser and at the exit, the pressure difference between entrance and exit and flow of artificial blood pump with different taper rotors are simulated, and then the influence rules of rotor taper on the performance of cone-shaped helical pump are revealed. In order to verify the correctness of theoretical analysis, rotors with three different tapers are manufactured, physical model of artificial blood pump are built, and then the actual lift and flow of blood pump with different rotors are measured respectively. The results show that taper of rotor increases, the circumfluence of blood near the front and rear diffuser decreases, the blood flows more smoothly, the energy consumption is less, and then the guide role of blade is greater. The blood at the exit of blood pump flows along the axial direction steadily. As taper of rotor increases, the pressure difference between the entrance and exit and the flow of blood pump increase subsequently. The flow condition of blood and performance of blood pump with No.3 rotor are the best. The proposed research analyzes the influence of rotor taper on performance of blood pump quantitatively, and provides the theoretical reference for the design and improving of cone-shaped helical pump.

Theoretical aspects and sensing demonstrations of cone-shaped inwall capillary-based microsphere resonators

In this paper, a detailed theoretical study on the characteristics of cone-shaped inwall capillary-based microsphere resonators is described and demonstrated for sensing applications. The maximum, minimum, slope, contrast, and width of the Fano resonance are analyzed. As the transmission coefficient of the capillary resonator increases, the absolute value of the slope of Fano resonances increases to reach its maximum, which is useful for sensors with an ultra-high sensitivity. There occurs another phenomenon of electromagnetically induced transparency when the reflectivity at the capillary–environment interface is close to 100%. We also experimentally demonstrated its capability for temperature and refractive index sensing, with a sensitivity of 10.9 pm∕°C and 431 d B∕RIU basedon the Fano resonance and the Lorentzian line shape, respectively.

基于窄带高分辨特征的锥体目标参数估计

利用参数特征对空间进动锥体进行识别可有效区分真假目标。为获取准确的参数特征,现阶段研究一般围绕宽带雷达所输出的目标高分辨距离像序列开展,但也存在着对雷达带宽要求高、不利用实际工程应用的局限。针对这一问题,提出了一种基于窄带雷达提取目标高分辨特征并完成参数估计的方法。首先建立了目标运动模型,对窄带观测下目标回波调制特性进行分析;在此基础上定义目标伪距离像序列,并利用目标回波中所包含散射中心微多普勒频率与相位信息变化完成了伪距离像序列的提取,根据不同视角观测到的伪距离像序列差异对锥体高度、底面半径及质心位置等目标参数进行估计,并设计了二级剔除结构选出了正确的估计结果;最后开展了基于电磁计算数据的仿真实验。实验结果表明该算法在高信噪比条件下估计精度优于97%,相比传统方法提高超过5%,且在5 dB的信噪比条件下平均参数估计精度仍然优于80%,应用门限较传统算法提高9 dB,说明了所提算法的有效性和稳健性。

弹体尾部斜锥面形状对侵彻偏转的影响

针对弹体斜侵彻多层靶时弹道发生的偏转问题,建立了弹体尾部为斜锥面结构的弹体侵彻偏转理论计算模型,获得了当速度为0.2~1.2km/s、着角为-30°~20°、弹体半径为30~60 mm、尾飘斜面与弹轴的夹角为0°~4°时偏转随尾部结构的变化规律,通过与试验结果进行对比,验证了模型的准确性。结果表明:弹体侵彻仰靶时,弹尾形成负的偏转力矩,弹体产生“低头”效果;弹体侵彻俯靶时,弹尾形成正的偏转力矩,弹体产生“抬头”效果;弹体尾部斜锥面产生的垂直弹轴的偏转力矩约为平行弹轴的偏转力矩的100倍;增大尾飘斜面与弹轴的夹角、尾飘长度、弹体半径均可增大偏转力矩;与增大尾飘长度相比,增大尾飘斜面与弹轴的夹角对增大偏转力矩更有效。

锥形闪烁体探测器在笔形束扫描式质子放疗系统质控中的应用

笔形束扫描式(Pencil Beam Scanning,PBS)质子系统使得质子调强技术得到了广泛的应用。该技术能更好地实现对危及器官的保护,但也给质子系统的质控带来了更大的挑战。为提高质控效率,评估了XRV-124锥形闪烁体探测器在PBS系统质控中的应用可行性。该探测器实现了单次摆位同时完成对束斑大小的测量、束流影像中心一致性的验证、Star-shot测试以及机械性能的检测等质控工作。对XRV-124探测器各项测量数据的结果进行了详细分析并与传统质控方法进行了对比,结果显示其在满足质控需求的同时,将质控时间缩短了2/3。该方法已成功应用于合肥离子医学中心Varian ProBeam质子放疗系统质控中,表明XRV-124探测器可广泛应用于国内同类型质子放疗系统,提升质控效率,降低频繁摆位引入的人为误差。

起伏地表下建筑物顶端雷电回击电磁场特性模拟研究

采用时域有限差分(finite-difference time-domain,FDTD)法,分析研究起伏地表下建筑物顶端的雷电回击电磁场特征,给出了锥形山体上的建筑物对雷电回击电磁场的影响,并进一步对真实地形山顶建筑物的雷电回击电磁场的传播特性进行了仿真研究。结果表明:相比于平坦地表,锥形山体的角度和建筑物高度会对雷电回击电磁场产生影响。锥形山体角度越大,垂直电场和水平磁场的峰值越大,且垂直电场峰值呈线性增长,锥形山体引起的电场峰值与平坦地表的电场峰值比为4~8;山顶建筑物的高度越高,垂直电场波形的峰值越大,山顶建筑物高度引起的垂直电场峰值与山顶无建筑物时的垂直电场峰值的比值基本呈对数增长,高度小于100 m时,增幅为100%~150%;随着雷电回击通道与山体之间观测距离的增加,建筑物高度增加引起的垂直电场的峰值先增强再逐渐减弱。以青岛大涧山雷达塔为例的仿真结果表明,建筑物顶端的雷电回击垂直电场的峰值明显大于理想平坦地表的情况,且其峰值增大了3.8倍,但是对水平磁场影响非常小。

辅助药型罩对射流性能的影响

辅助药型罩结构能实现超聚能效应,有效地提高破甲威力。为了研究辅助药型罩对射流性能的影响,设计一种辅助型双锥药型罩,通过AUTODYN数值模拟的方法,分析辅助药型罩材料和结构对射流性能的影响。结果表明,当主药型罩采用铜,辅助药型罩材料为钨时,射流综合性能优异;设计主药型罩大锥角70°,小锥角40°,壁厚2 mm,辅助药型罩厚度在2~6 mm时,随着厚度增加,射流性能改善,6 mm时射流性能最佳,辅助药型罩直径在20~28 mm时,26 mm时射流综合性能最佳。

规整微纳米锥结构柔性压力传感器的研究

首先利用电化学阳极氧化法,制备锥形阳极氧化铝(C-AAO)模板,然后采用原位聚合法和旋涂法,构建规整微纳米锥结构聚苯胺-聚甲基丙烯酸甲酯(PANI-PMMA)柔性导电膜,最后通过互锁封装制备规整微纳米锥结构柔性压阻传感器,并对规整微纳米锥结构PANI-PMMA导电膜的表面形貌、傅立叶变换红外光谱及传感器的传感性能进行测试分析。结果表明,微纳米锥长度为(1.38±0.03)um的传感器在0~2.3kPa范围内表现出108.27kPa^(-1)的高灵敏度、2000次载荷加载和卸载下循环稳定性和±4.72%的低迟滞性,并且可以对手腕运动状态和身体运动状态进行监测。

65Mn弹簧钢拉拔断裂分析改进

采用化学成分、力学性能、宏观形貌、金相检验和扫描电镜相结合的方法,对65Mn盘条拉拔断裂的原因进行分析。样品心部裂纹孔洞处存在严重的Mn、S、P偏析,是65Mn盘条拉拔断裂的主要原因。同时,硅酸盐夹杂物含量控制偏高,增加拉拔断裂发生的几率。通过将中包钢水过热度控制在30℃内、LF精炼炉渣碱度提高到3.5、精炼后软吹时间大于10 min和连铸拉速控制在1.9±0.1 m/min,解决了65Mn弹簧钢心部偏析和拉拔断丝问题。

四种镍钛单支锉预备弯曲根管的成形效果比较

目的:比较4种镍钛单支锉预备弯曲根管的成形效果。方法:选择64颗离体上颌第一磨牙的近中颊根管,根据弯曲度分为中度弯曲组、重度弯曲组,每组再随机分成4个亚组(n=8),分别用4种镍钛单支锉WaveOne Gold、Reciproc Blue、M3-L以及锋度V Blue预备根管,记为WG组、RB组、M3组和VB组。记录各组根管预备时间。采用锥形束CT测算根管偏移量、轴中心率及弯曲度变化。结果:预备过程中均未发生器械变形或折断。同一弯曲程度下各亚组根管预备时间差异无统计学意义(P>0.05)。重度弯曲根管中,M3组弯曲度变化值最小。4种单支锉产生的根管偏移量均<0.30 mm;距根尖3 mm处,WG组根管偏移量最大;距根尖5 mm处,WG组根管偏移量较小,轴中心率最接近1。结论:虽然4种镍钛单支锉均能较好地维持弯曲根管原有的解剖形态,但WaveOne Gold在根管中段具有更好的中心定位能力,M3-L在维持根管弯曲角度上更具优势。

熟料冷却风机锥形口流量测量装置的现场改造

某海外水泥项目熟料冷却风机锥形口流量测量装置选型偏小,导致冷却风机风量PID调节回路投运不稳,为满足PID投运要求,提高测量装置灵敏度,对冷却风机锥形口流量测量装置进行了改造。详细介绍了锥形口流量测量装置现场改造及制作安装要求、流量系数计算方法、现场标定结果等。改造后,在设计风量为29 965m^(3)/h时,差压值达373Pa,管道系统静压增加了248Pa,提高了流量测量装置的风量检测灵敏度,保证了PID调节回路的稳定自动调节。

拉伸法制备微纳光纤的设计与研究

微纳光纤通常采用光纤拉锥法制备.对原有装置进行改进,增加电机和控制器搭建火焰加热电机拉伸法制备微纳光纤的实验平台,实现了微纳光纤的自动化制备.探究了光纤直径与拉伸距离、拉伸速度、火焰高度等的关系.理论推导出单侧拉伸过程中锥区直径与拉伸长度的关系,通过对不同速度下锥区形状的测量,解释了拉伸速度影响光纤直径的原因.

基于锥形束CT对不同矢状骨面型儿童上颌骨与颧骨形态的研究

目的通过锥形束CT(CBCT)探讨不同矢状骨面型错畸形儿童上颌骨与颧骨宽度、突度的差异,分析上颌骨与颧骨之间的相关性,及上颌骨和颧骨形态对于面部美观的意义。方法回顾性分析2023年5月至2024年8月于新疆医科大学第一附属医院行CBCT及头颅侧位片检查的135例错畸形儿童颧骨及上颌骨的相关影像学指标,包括鼻颧角(fmo-nfmo)、颧上颌角(zm-ss-zm)、面宽(Za-Za)、颧突点-耳点径(mp-po)、颧颌缝点-乳突点径(zm-ms)、上颌第一磨牙区、第一、第二前磨牙区基骨宽度及牙槽骨宽度(MBW、MAW、PBW、PAW、SPBW、SPAW)、前颌间距离(AIMD)、后颧间距离(PIZD)、后颞间距离(PITD),比较骨性Ⅰ、Ⅱ、Ⅲ类矢状骨面型患者CBCT影像学参数差异及颧骨和上颌骨之间的相关性,并分析面中部骨骼发育对于面部形态的意义。结果(1)MBW在骨性Ⅲ类显著小于骨性Ⅰ、Ⅱ类(P<0.05),MAW、SPBW、SPAW、PBW、PAW在三组间差异均无统计学意义(P>0.05);(2)Za-Za、AIMD、PIZD及PITD在骨性Ⅲ类显著小于骨性Ⅰ、Ⅱ类(P<0.05);(3)zm-ss-zm、mp-po和zm-ms在骨性Ⅲ类显著小于骨性Ⅰ、Ⅱ类(P<0.05),fmo-n-fmo在三组间差异均无统计学意义(P>0.05);(4)Za-Za、PIZD、PITD与MBW、MAW、SPBW、SPAW、PBW、PAW均呈显著正相关关系(P<0.05);(5)zm-ss-zm与fmo-n-fmo呈正相关关系(P<0.01),zm-ms与mp-po呈正相关关系(P<0.01)。结论骨性Ⅲ类患者的上颌基骨和颧骨在水平向和矢状向的生长量较骨性Ⅰ、Ⅱ类小,面部更显平坦甚至凹陷;上颌骨与颧骨的宽度、突度之间有相关性。

阳极支撑型锥管串接式直接碳固体氧化物燃料电池组的制备及性能

针对阳极支撑型直接碳固体氧化物燃料电池(DC-SOFC)的浓差极化阻抗大的问题,本研究采用改进后的凝胶注模法制备了阳极支撑型锥管状固体氧化物燃料电池(SOFC)。通过适当增加溶剂的含量,改善了浆料的流动性,提高了成品的质量;通过增大造孔剂的含量,提高了阳极的孔隙率,减小了气体的扩散阻力。改进后的SOFC以氢气为燃料,在800℃运行时,开路电压为1.05 V,电化学阻抗谱的极化阻抗更小,电池的最大功率密度为0.67 W×cm^(–2)(阴极有效面积为2.2 cm^(2)),明显优于改进前的SOFC。改进后的SOFC直接采用担载质量分数5%K的活性炭为燃料,在800℃运行时,开路电压为1.030 V,接近理论电压,最大功率密度达0.74 W×cm^(–2),以400 mA进行恒流放电,碳燃料的有效利用率为31%,高于改进前电池的碳燃料的有效利用率17%。将改进后的4个锥管状单电池串联成电池组,直接采用担载质量分数5%K催化剂的活性炭为燃料,在800℃运行时,最大功率达8.0 W,高于改进前的4节DC-SOFC电池组(4.1 W),该电池组碳燃料的有效利用率为15%,峰值功率密度可达0.91 W×cm^(–2),超过了文献报道的最高值。

大口径方锥体形风道设计结构改进

对大口径方锥体形风道的设计结构进行了改进,提出对于长宽比例较大的风道应将导向板与外部加固肋的设计进行综合考虑,借助导向板将单一风道分隔成多腔体,使导向板承担导流和拉力载荷的双功能,这样设计可以大幅度减小外部加固肋和风道壁板的规格。利用Solidworks软件建立优化前和优化后的结构模型,进行有限元分析,对比在设计压力下的分析结果。结论认为优化后的结构应力值低,变形量很小,可节约材料50%以上。

基于ANSYS/LS-DYNA数值模拟计算对弧锥结合药型罩的优化设计

为研究弧锥结合药型罩形成爆炸成型弹丸过程中,药型罩圆弧-锥角部分对爆炸成型弹丸性能的影响,控制其他变量保持不变,取圆弧-锥角在药型罩母线长度所占比例分别为1/7、2/6、3/5、4/4、5/3、6/2、7/1,采用数值模拟软件ANSYS/LS-DYNA建立数值模型进行模拟计算,得到相应数值模拟结果,最后通过试验验证数值模拟结果,分析了不同比例圆弧-锥角药型罩形成爆炸成型弹丸数值模拟结果中的速度、长度、压实状况等参数。结果表明,爆炸成型弹丸的速度随圆弧-锥角比例的增大而逐渐减小并在比例为3/5后保持稳定;弹丸断裂时间随圆弧-锥角比例的增大而减小;圆弧-锥角比例为3/5~5/3之间弹丸均断裂为3个部分,6/2比例从中间断裂,3/5至7/1比例中,变化不明显;综合比较速度、断裂时间、断裂部分数等参数,圆弧-锥角比例为5/3速度最大为2123 m/s、断裂数量最少为3、压实程度良好,飞行性能和侵彻能力等综合性能更好。通过试验测量弹丸速度,与数值模拟结果误差在5%左右,充分证实研究结果的可靠性。