Mitigating end effects of EMD using non-equidistance grey model

Aiming at mitigating end effects of empirical mode decomposition （EMD）, a new approach motivated by the non- equidistance grey model （NGM） termed as NGM（1,1） is proposed. Other than trapezoid formulas, the cubic Hermite spline is put forward to improve the accuracy of derivative to the accumulated generating operation （AGO） series. Hopefully, it is worth stressing that the proposed NGM（1,1） model is particularly useful for predicting uncertainty data. Qualitative and quantitative comparisons between the proposed approach and other well-known algorithms are carried out through computer simulations on synthetic as well as natural signals. Simulation results demonstrate the proposed method can reduce end effects and improve the decomposition results of EMD.

Optimization of the End Effect of Hilbert-Huang transform(HHT)

In fault diagnosis of rotating machinery, Hil- bert-Huang transform （HHT） is often used to extract the fault characteristic signal and analyze decomposition results in time-frequency domain. However, end effect occurs in HHT, which leads to a series of problems such as modal aliasing and false IMF （Intrinsic Mode Func- tion）. To counter such problems in HHT, a new method is put forward to process signal by combining the general- ized regression neural network （GRNN） with the bound- ary local characteristic-scale continuation （BLCC）. Firstly, the improved EMD （Empirical Mode Decompo- sition） method is used to inhibit the end effect problem that appeared in conventional EMD. Secondly, the gen- erated IMF components are used in HHT. Simulation and measurement experiment for the cases of time domain, frequency domain and related parameters of Hilbert- Huang spectrum show that the method described here can restrain the end effect compared with the results obtained through mirror continuation, as the absolute percentage of the maximum mean of the beginning end point offset and the terminal point offset are reduced from 30.113% and 27.603% to 0.510% and 6.039% respectively, thus reducing the modal aliasing, and eliminating the false IMF components of HHT. The proposed method caneffectively inhibit end effect, reduce modal aliasing and false IMF components, and show the real structure of signal components accuratelX.

A method for constraining the end effect of EMD based on sequential similarity detection and adaptive filter

Aimed at the problem of the end effect when using empirical mode decomposition(EMD),a method for constraining the end effect of EMD is proposed based on sequential similarity detection and adaptive filter.The method divides the signal into many wavelets,and it changes the initial wavelet length to select the best initial wavelet that has the minimum error and maximum number of matching seed wavelets,and the wavelet slopes are used for pre-matching and secondary matching to speed up the matching speed.Then,folded self-adaptive threshold is used to select multiple seed wavelets,and finally the end waveform is predicted and expanded according to the adaptive filter method.The proposed method is used to analyze the non-stationary nonlinear simulation signal and experimental signal,and it is compared with the mirror extension and RBF extension methods.The orthogonality index and similarity index of the EMD results of the extended signal after the proposed method are better than those of the other methods.The results show that the proposed method can better constrain the end effect,and has certain validity,accuracy and stability in solving the end effect problem.

Realizing profits immediately:disposition effect of open-end fund investors in China

This paper explores the disposition effect, the tendency of investors to hold losing investments too long and sell winning investments too soon, by analyzing a unique data set that consists of the buying and selling positions of open-end fund investors in China. Results show that investors' buying and selling behaviors are significantly affected by fund performance. The reasons that lie behind such results are mainly related to the non-persistence of fund performance. When fund performance is non-persistent, investors are not clear about the future returns on funds. So, investors, especially individual investors, would have to realize the profits on hand immediately. Meanwhile, fund investors are highly sensitive to fund age and loading fees, but not sensitive to management fees charged by funds when they buy or sell fund shares.

A new method to reduce end effect of linear induction motor

A new method to compensate the end effect of a linear induction motor （LIM） in low-speed maglev vehicles is proposed. With this method, the motors are close to each other so that the front motor＇s exit-end magnetic field extends into the next motor＇s entry zone. As a result, the motor＇s magnetic field traveling wave become continuous and the end effect of short primary LIMs is greatly weakened. In the analysis of the air-gap magnetic field distribution, the LIM is assumedly divided into two identical motors vcith the distances of 20, 40, 60, and gO ram. The results show that the air-gap magnetic field is still continuous within these distances due to LIM＇s end effect. As the distance between two motors increases, the distortion of the air-gap magnetic field becomes more severe. Then, we investigate the relationship between the secondary speed and the thrust in three cases, i.e., a single LIM, two motors divided with 72 mm with pole pitch corrected, and two motors divided with 60 mm without the pole pitch being corrected. We find that the thrust has a small decrease when the speed increases, which means that the magnetic field is already continuous and its amplitude is approximately a constant. Furthermore, the thrust loss of case 3 is more than that of case 2, which indicates that the pole pitch correction is effective.

Performance Analysis of Nested-loop Secondary Linear Doubly-fed Machine Considering End Effects

Nested-loop secondary linear doubly-fed machine(NLS-LDFM) is a novel linear machine evolved from rotary brushless doubly-fed induction machine, which has a good application prospect in linear metro. In order to analyze the performance of NLS-LDFM, the mechanism and action rules of end effects are investigated in this paper. Firstly, the mechanism of static and dynamic end effects is analyzed in aspect of direct coupling, winding asymmetry and transient secondary current. Furthermore, based on the winding theory for short primary linear machines, the machine parameters are established qualitatively considering pulsating magnetic field of NLS-LDFM. Finally, the NLS-LDFM performance analysis is supplemented by the finite element algorithm(FEA) simulation and experiments under different operating conditions.

Extended Anode Effect for Tube Inner Coating of Non-Conductive Ceramics by Pulsed Coaxial Magnetron Plasma

For uniform tube inner coating of non-conductive thin films, the double-ended coaxial magnetron pulsed plasma (DCMPP) method was investigated. In this study, coating of TiN and TiO2 was performed. It was clearly shown that the extended anode effect was strongly influenced by the electric resistance of the coated thin films on the inner surface of an insulator tube. Additionally, high frequency (100 kHz) was better for relatively high plasma density. On the other hand, in the case of titanium oxide deposition, negative ion productions drastically decrease the deposition rate and the shifting velocity of plasma main position for coated TiO2 films.

Study of Reducing Non-Ideal Effects Based on TiN Sensitive Electrode with Front-End Offset Circuit

The structure of the extended gate ion sensitive field effect transistor (EGISFET) is similar to the structure of the ion sensitive field effect transistor (ISFET).Moreover,the non-ideal effect of EGISFET is the main impediment to development of commercial processes for sensitive devices.It is necessary to promote the stability and reliability of the devices by employing calibration circuits and the better fabrication conditions.The temporal drift exists in the entire measurement experiment. Furthermore,in this study we can reduce the temporal drift effect which influences the stability of the TiN sensitive electrode with the differential front-end offset circuit.The measurement system combines with shifting circuit,differential and instrument amplifiers.We employ the calibration circuit to compare with the variations of the output voltage,and expectably improve the stability and reliability of the TiN sensitive electrode by the novel calibration circuit.

Study on the squeezing effect of open-ended pipe piles

During the installation of a pipe pile,the soil around the pile will be squeezed out. This paper deals with this squeezing effect of open-ended pipe piles using the cylindrical cavity expansion theory. The characteristics of soil with different tension and compression moduli and dilation are involved by applying the elastic theory with different moduli and logarithmic strain. The closed-form solutions of the radius of the plastic region,the displacement of the boundary between the plastic region and the elastic region and the expansion pressure on the external surface of the pipe piles are obtained. When obtaining these solutions,the soil plug in the open-ended pipe pile is considered by employing an incremental filling ratio to quantify the degree of soil plugging. Moreover,the effects of the ratio of tension and compression moduli,angle of dilation and incremental filling ratio on the radius of the plastic region and the expansion pressure on the external surface of the pipe pile are investigated. The parametric analyses show that it is necessary and important to consider the difference between the tension modulus and compression modulus,dilation angle and incremental filling ratio for studying the squeezing effect of open-ended pipe pile installation. It is concluded that the analytical solutions presented in this paper are suitable for studying the squeezing effect of open-ended pipe piles.

Researches on End Effects of Permanent Magnet Electromagnetic Launchers

Brushless DC linear motors have considerable advantages of simpler structure,higher efficiency,higher thrust density and so on.They are well suited for many domains such as electromagnetic launch and launch-assist,but it is inevitable that there exist longitudinal end effects in the mover of the motor caused by longitudinal discontinuities.The serious trouble caused by longitudinal end effects is the thrust ripple.Firstly,by using the method of finite element simulation,this paper studies the distribution of magnetic field and energy in the end region when the mover is in different positions in the range of a polar pitch and discusses the effective methods of reducing the longitudinal end effects.Then the law of the influence of different mover length on the longitudinal end effects has been studied by using analytic methods,and the influences of the mover length and its end geometry shape on the longitudinal end effects have been verified for the test model by using the method of finite element simulation.

空穴效应对连杆小头轴承润滑及动力学特性的影响

将热弹流理论与活塞连杆组柔性多体动力学分析结合,利用AVL EXCITE软件建立连杆小头轴承润滑模型,并以油膜压力、轴心轨迹及润滑油填充率确定连杆小头轴承空穴位置,研究空穴效应对连杆小头轴承润滑及动力学特性产生的影响。结果表明,在发动机整个循环工况中连杆小头轴承一直存在空穴现象。考虑空穴后平均峰值油膜压力降低了6.5 MPa,平均油膜厚度降低了1.35μm,活塞销相对连杆小头轴承的速度及加速度分别增大了1.57μm/s和0.25μm/s^(2),连杆小头轴承润滑性能减弱,所受冲击增大。

考虑空穴效应的连杆小头摩擦副润滑特性与冲击影响研究

为改善连杆小头轴承润滑及活塞销冲击特性,基于粗糙峰接触理论、平均流量模型及弹流润滑理论,以某高压共轨4缸柴油机为研究对象,运用AVL EXCITE Power Unit软件搭建混合润滑活塞连杆组多体动力学模型,研究了考虑空穴条件下不同转速对连杆小头摩擦副润滑及冲击特性的影响规律。研究结果表明:标定功率转速2400 r/min下,在做功时刻1080°后峰值油膜压力达到最大值197.1 MPa,最小油膜厚度达到最小值1.8μm,而润滑油填充率在整个发动机循环过程中均低于0.12。在怠速800 r/min、最大扭矩转速1600 r/min、标定功率转速2400 r/min下,进气、压缩、做功、排气4个冲程过程中,空穴区域由连杆小头轴承下半区转移至上半区、再转移至下半区。转速升高会导致峰值油膜压力增大,最小油膜厚度减小,粗糙接触压力增大,活塞销Z向速度峰值加大,对连杆小头轴承冲击加重,在缸内最高燃烧压力时刻,800 r/min,1600 r/min,2400 r/min下的平均润滑油填充率均值为0.84,0.70,0.69,因润滑油填充率随转速的升高而降低,空穴程度加重。

均质黏性土中静压沉桩桩土界面孔压增量及有效土压室内试验研究

研究饱和黏性土中静压沉桩引起的桩土界面孔压增量及有效径向应力的变化规律对工程实践具有重要意义。利用自制的大比例模型试验系统,通过双壁开口和闭口管桩,实现了开口和闭口桩桩身表面嵌入式安装微型测试元件,得到了考虑孔压增量的桩土界面有效径向应力的变化规律。研究结果表明:入土深度越大,桩土界面孔压增量及有效径向应力越大,闭口桩桩土界面超孔压大于开口桩;桩身上部桩土界面超孔压和有效径向应力小于桩身下部;同一入土深度,随着桩身h/L的增加,桩土界面土压力存在侧压力“退化”的现象;特定试验条件下,闭口和开口桩桩土界面超孔压与上覆有效土体自重比值最大值分别是61.2%和52.1%,桩土界面有效径向应力是超孔压的3.76~5.46倍。桩土界面超孔压和有效径向应力与桩身h/L位置有关。

谷胱甘肽联合西地那非治疗勃起功能障碍患者临床疗效及对血管内皮功能的影响

目的探究谷胱甘肽联合西地那非治疗勃起功能障碍(ED)患者临床疗效及对血管内皮功能、炎性因子、勃起功能的影响。方法选取2022年10月—2023年10月新疆维吾尔自治区人民医院泌尿中心诊治ED患者89例作为研究对象,随机数字表法分为单药组44例和联合组45例。单药组给予西地那非口服治疗,联合组在单药组基础上给予还原型谷胱甘肽片口服治疗,2组患者均连续治疗1个月。观察2组患者治疗前、治疗结束时及治疗后1个月的血管内皮功能(NO、ET、VEGF、ES)、炎性因子(hs-CRP、IL-6、IL-8、IL-10)、勃起功能(IIEF-5、QEQ、EHS、PSV)变化,比较2组临床疗效、不良事件发生率。结果治疗结束后1个月,联合组临床治疗总有效率为91.11%,高于单药组的75.00%(χ^(2)/P=4.121/0.042);治疗结束时及治疗结束后1个月,联合组患者血清NO、VEGF水平显著高于单药组,ET水平显著低于单药组(治疗结束时:t/P=5.323/<0.001,3.808/<0.001,3.683/<0.001;治疗结束后1个月:t/P=2.615/0.011,3.197/0.002,3.089/0.003);血清hs-CRP、IL-6水平显著低于单药组(治疗结束时:t/P=8.323/<0.001,2.364/0.020;治疗结束后1个月:t/P=6.787/<0.001,2.662/0.009);IIEF-5、QEQ、EHS及PSV均显著高于治疗前,其中EHS及PSV也显著高于单药组(治疗结束时:t/P=6.410/<0.001,4.066/<0.001;治疗结束后1个月:t/P=8.928/<0.001,4.532/<0.001);2组患者不良事件发生率比较差异无统计学意义(P>0.05)。结论谷胱甘肽联合西地那非能够有效改善ED患者血管内皮功能及勃起功能,同时显著降低患者炎性因子水平,且对于ED患者具有显著临床疗效及安全性。

胸腰段椎管硬膜外囊肿显微手术中尾端技术应用(附12例分析)

目的:探究显微镜下胸腰段椎管内硬膜外脊膜囊肿(spinal extradural meningeal cysts,SEMC)瘘口修补结合囊肿尾端技术处理的疗效和临床应用的可推广性。方法:回顾经电生理监测显微手术胸腰段SEMC瘘口修补结合囊肿尾端技术(切除囊肿尾端囊袋、囊肿尾端与正常硬脊膜交界处微小切口贯通脑脊液后常规缝合)的12例患者资料,结合文献传统手术方法进行分析。结果:平均随访14个月期间影像学囊肿完全消失9例,大部分消失1例,椎间孔内侧残留囊肿2例,无1例存在硬膜囊受压表现,无复发病例。术前腰背痛和/或下肢痛11例,出院时疼痛缓解或消失,随访3个月后疼痛改变与出院时比较差异无统计学意义。患者下肢无力及排尿功能障碍逐渐恢复,术后未出现新的神经功能缺失。椎板棘突解剖复位良好、无椎管狭窄和畸形病例。结论:电生理监测显微手术胸腰段SEMC瘘口修补结合囊肿尾端技术可以有效解决活瓣问题,闭合囊肿,无明显并发症,临床可行。

计及边端效应的直线式移相变压器等效电路分析

直线式移相变压器是一种新型移相变压器,具有绕组结构简单、易于模块化和可任意角度移相的优点。其直线型结构导致变压器存在边端效应,进而导致气隙磁场产生畸变。为了计算出边端效应产生的影响,该文从直线式移相变压器的磁场进行深入分析,并建立计及边端效应的等效电路模型。首先,基于一维场理论对直线式移相变压器进行数学分析,根据场路复功率相等的原则,推导出等效电路二次侧参数,并计算出边端效应修正系数;然后,根据边端效应的分析结果和直线感应电机的等效电路拓扑建立计及边端效应的等效电路模型;最后,通过直线式移相变压器的二维有限元仿真模型和小功率样机的实验,验证了建模方法的合理性和等效电路模型的准确性。

关节镜下前交叉韧带重建术中保留残端与不保留残端治疗前交叉韧带损伤患者的效果

目的:比较关节镜下前交叉韧带(anterior cruciate ligament,ACL)重建术中保留残端与不保留残端治疗ACL损伤患者的效果。方法:选取2021年2月—2022年6月中国人民武装警察部队广东省总队医院收治的102例ACL损伤患者。根据随机数表法将其分为对照组与研究组,各51例。两组均给予关节镜下ACL重建术,对照组给予不保留残端,研究组给予保留残端。比较两组术前和术后3个月、6个月膝关节功能、膝关节活动度、本体感觉功能、韧带损伤程度。结果:术前和术后3个月、6个月,两组Lysholm评分比较,差异无统计学意义(P>0.05)。术前和术后3个月、6个月,两组膝关节活动度比较,差异无统计学意义(P>0.05)。术后3个月、6个月,研究组被动活动察觉阈值和被动角度均低于对照组,差异有统计学意义(P<0.05)。术前和术后3个月、6个月,两组国际膝关节文献委员会膝关节评估表(the international knee documentation committee knee uation form,IKDC评分)评分比较,差异无统计学意义(P>0.05)。结论:关节镜下ACL重建术中保留残端与不保留残端都能够对ACL损伤患者进行有效的治疗,但ACL损伤患者保留残端可更为显著地改善本体感觉功能。

结构参数对环形线性感应电磁泵性能的影响分析

环形线性感应电磁泵(ALIP)是液态金属反应堆中泵送冷却剂的关键驱动设备。在电磁泵的设计和分析中,结构参数是影响电磁泵输出性能的重要因素。为了进一步研究环形线性感应电磁泵结构设计参数对输出性能的影响,首先利用有限元分析软件建立考虑端部效应和环形导电管道影响的环形线性感应电磁泵仿真模型,然后基于模型计算分析了不同齿槽比、流道高度和管道壁厚度对电磁泵的磁密分布、电磁力密度分布和输出电磁力的影响,最后进一步对比分析了不同结构参数下环形线性感应电磁泵的输出特性和效率,研究结果为环形线性感应电磁泵的结构参数优化提供了参考依据。

标准参与、产业链协同与企业高质量发展——基于中国高端装备制造企业的实证分析

在外部环境高度不确定的背景下,中国企业正面临技术和市场资源双重空间挤压的难题,实现高质量发展是破局的关键。技术标准作为技术公共化的载体,具有很强的资源扩展属性,但其在企业高质量发展过程中发挥怎样的作用以及中间机制还不明晰。本文以2008~2022年362家上市高端装备制造企业为研究样本,实证分析标准参与对企业高质量发展的影响,以及产业链协同在其中的作用机制。结果表明:标准参与对产业链协同和企业高质量发展均具有正向影响,产业链协同在标准参与和高质量发展中存在遮掩效应。进一步研究发现,国有、西部地区以及中美贸易摩擦前企业的标准参与更有助于实现高质量发展。本文的研究发现为企业的高质量发展提供了有益思路,也为政府制定规范性和产业性政策提供了一定的参考。

中西医结合疗法对终末期肾病患者肾功能的影响及JAK/STAT途径的调控作用

目的观察参芪地黄汤结合重组人促红细胞生成素与左卡尼汀治疗对终末期肾病患者肾功能的影响及Janus激酶/信号转导与转录激活子(JAK/STAT)途径的调控作用。方法选择2019年10月至2021年10月在邢台医学高等专科学校第二附属医院就诊的144例终末期肾病患者作为研究对象。将患者按随机数字表法分参芪地黄汤治疗组和常规治疗组,每组72例。两组患者均行维持性血液透析,常规治疗组给予重组人促红细胞生成素和左卡尼汀治疗,参芪地黄汤治疗组加用参芪地黄汤(组成:生黄芪、桑寄生、旱莲草、猪苓、茯苓皮、生薏苡仁、丹参、石韦各30 g,党参、山茱萸、泽兰、淮山药各15 g,生地黄、荔枝核、蚕砂、莪术各10 g,决明子6 g),每日1次,共治疗3个月。观察不同治疗方式两组患者治疗后的临床疗效和肾功能、微炎症状态及血清JAK/STAT途径相关蛋白水平的变化,并记录不良反应发生情况。结果参芪地黄汤治疗组总有效率高于常规治疗组〔90.28%(64/72)比77.78%(55/72),P<0.05〕。两组治疗后残余肾功能(RRF)、24 h尿蛋白、血尿素氮(BUN)、血肌酐(SCr)和炎症因子〔超敏C-反应蛋白(hs-CRP)、白细胞介素-6(LL-6)、肿瘤坏死因子-α(TNF-α)〕水平均较治疗前明显降低,参芪地黄汤治疗组治疗后RRF明显高于常规治疗组(mL/min:4.82±1.18比3.96±1.05),而24 h尿蛋白(mg:62.26±12.16比97.71±16.28)、BUN(mmol/L:16.25±3.64比20.65±4.13)、SCr(μmol/L:242.25±25.62比280.62±26.63)、hs-CRP(mg/L:5.86±1.15比7.78±1.32)、IL-6(ng/L:3.26±0.64比4.62±1.13)、TNF-α(μg/L:29.23±5.64比32.66±6.13)含量均明显低于常规治疗组(均P<0.05)。治疗后参芪地黄汤治疗组JAK、STAT均较治疗前呈增加趋势,而磷酸化JAK(p-JAK)、磷酸化STAT(p-STAT)均较治疗前呈降低趋势(均P<0.05),常规治疗组血清JAK/STAT途径相关蛋白水平变化不显著(均P>0.05),故参芪地黄汤治疗组治疗后JAK、STAT均明显高于常规治疗组〔JAK(μg/L):1.46±0.28比1.26±0.26,STAT(μg/L):1.37±0.25比0.99±0.24,均P<0.05〕,p-JAK、p-STAT均明显低于常规治疗组〔p-JAK(μg/L):0.45±0.08比0.65±0.13,p-STAT(μg/L):0.66±0.13比0.82±0.28,均P<0.05〕。两组患者不良反应发生率差异无统计学意义〔13.88%(10/72)比9.72%(7/72),P>0.05〕。结论在重组人促红细胞生成素与左卡尼汀治疗基础上服用参芪地黄汤可有效抑制JAK/STAT信号通路,改善终末期肾病患者肾功能以及微炎症状态,从而提高治疗效果。