Towards refining temporal specifications into hybrid systems

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The Neutral Grounding Resistor Sizing Using an Analytical Method Based on Nonlinear Transformer Model for Inrush Current MitigationGholamabas M.H.Hajivar Shahid Chamran University,Ahvaz, Iranhajivar@S.S.MortazaviShahid Chamran University,Ahvaz, IranMortazavi_s@scu.ac.irMohsen SanieiShahid Chamran University,Ahvaz, IranMohsen.saniei@Abstract-It was found that a neutral resistor together with 'simultaneous' switching didn't have any effect on either the magnitudes or the time constant of inrush currents. The pre-insertion resistors were recommended as the most effective means of controlling inrush currents. Through simulations, it was found that the neutral resistor had little effect on reducing the inrush current peak or even the rate of decay as compared to the cases without a neutral resistor. The use of neutral impedances was concluded to be ineffective compared to the use of pre-insertion resistors. This finding was explained by the low neutral current value as compared to that of high phase currents during inrush. The inrush currents could be mitigated by using a neutral resistor when sequential switching is implemented. From the sequential energizing scheme performance, the neutral resistor size plays the significant role in the scheme effectiveness. Through simulation, it was found that a few ohms neutral grounding resistor can effectively achieve inrush currents reduction. If the neutral resistor is directly selected to minimize the peak of the actual inrush current, a much lower resistor value could be found.This paper presents an analytical method to select optimal neutral grounding resistor for mitigation of inrush current. In this method nonlinearity and core loss of the transformer has been modeled and derived analytical equations.Index Terms--Inrush current, neutral grounding resistor, transformerI.I NTRODUCTIONThe energizing of transformers produces high inrush currents. The nature of inrush currents have rich in harmonics coupled with relatively a long duration, leads to adverse effects on the residual life of the transformer, malfunction of the protection system [1] and power quality [2]. In the power-system industry, two different strategies have been implemented to tackle the problem of transformer inrush currents. The first strategy focuses on adapting to the effects of inrush currents by desensitizing the protection elements. Other approaches go further by 'over-sizing' the magnetic core to achieve higher saturation flux levels. These partial countermeasures impose downgrades on the system's operational reliability, considerable increases unit cost, high mechanical stresses on the transformer and lead to a lower power quality. The second strategy focuses on reducing the inrush current magnitude itself during the energizing process. Minimizing the inrush current will extend the transformer's lifetime and increase the reliability of operation and lower maintenance and down-time costs. Meanwhile, the problem of protection-system malfunction is eliminated during transformer energizing. The available inrush current mitigation consist "closing resistor"[3], "control closing of circuit breaker"[4],[5], "reduction of residual flux"[6], "neutral resistor with sequential switching"[7],[8],[9].The sequential energizing technique presents inrush-reduction scheme due to transformer energizing. This scheme involves the sequential energizing of the three phases transformer together with the insertion of a properly sized resistor at the neutral point of the transformer energizing side [7] ,[8],[9] (Fig. 1).The neutral resistor based scheme acts to minimize the induced voltage across the energized windings during sequential switching of each phase and, hence, minimizes the integral of the applied voltage across the windings.The scheme has the main advantage of being a simpler, more reliable and more cost effective than the synchronous switching and pre-insertion resistor schemes. The scheme has no requirements for the speed of the circuit breaker or the determination of the residual flux. Sequential switching of the three phases can be implemented through either introducing a mechanical delay between each pole in the case of three phase breakers or simply through adjusting the breaker trip-coil time delay for single pole breakers.A further study of the scheme revealed that a much lower resistor size is equally effective. The steady-state theory developed for neutral resistor sizing [8] is unable to explain this phenomenon. This phenomenon must be understood using transient analysis.Fig. 1. The sequential phase energizing schemeUPEC201031st Aug - 3rd Sept 2010The rise of neutral voltage is the main limitation of the scheme. Two methods present to control the neutral voltage rise: the use of surge arrestors and saturated reactors connected to the neutral point. The use of surge arresters was found to be more effective in overcoming the neutral voltage rise limitation [9].The main objective of this paper is to derive an analytical relationship between the peak of the inrush current and the size of the resistor. This paper presents a robust analytical study of the transformer energizing phenomenon. The results reveal a good deal of information on inrush currents and the characteristics of the sequential energizing scheme.II. SCHEME PERFORMANCESince the scheme adopts sequential switching, each switching stage can be investigated separately. For first-phase switching, the scheme's performance is straightforward. The neutral resistor is in series with the energized phase and this resistor's effect is similar to a pre-insertion resistor.The second- phase energizing is one of the most difficult to analyze. Fortunately, from simulation studies, it was found that the inrush current due to second-phase energizing is lower than that due to first-phase energizing for the same value of n R [9]. This result is true for the region where the inrush current of the first-phase is decreasing rapidly as n R increases. As a result, when developing a neutral-resistor-sizing criterion, the focus should be directed towards the analysis of the first-phase energizing.III. A NALYSIS OF F IRST -P HASE E NERGIZING The following analysis focuses on deriving an inrush current waveform expression covering both the unsaturatedand saturated modes of operation respectively. The presented analysis is based on a single saturated core element, but is suitable for analytical modelling of the single-phase transformers and for the single-phase switching of three-phase transformers. As shown in Fig. 2, the transformer's energized phase was modeled as a two segmented saturated magnetizing inductance in series with the transformer's winding resistance, leakage inductance and neutral resistance. The iron core non-l inear inductance as function of the operating flux linkages is represented as a linear inductor inunsaturated ‘‘m l ’’ and saturated ‘‘s l ’’ modes of operation respectively. (a)(b)Fig. 2. (a) Transformer electrical equivalent circuit (per-phase) referred to the primary side. (b) Simplified, two slope saturation curve.For the first-phase switching stage, the equivalent circuit represented in Fig. 2(a) can accurately represent behaviour of the transformer for any connection or core type by using only the positive sequence Flux-Current characteristics. Based on the transformer connection and core structure type, the phases are coupled either through the electrical circuit (3 single phase units in Yg-D connection) or through the Magnetic circuit (Core type transformers with Yg-Y connection) or through both, (the condition of Yg-D connection in an E-Core or a multi limb transformer). The coupling introduced between the windings will result in flux flowing through the limbs or magnetic circuits of un-energized phases. For the sequential switching application, the magnetic coupling will result in an increased reluctance (decreased reactance) for zero sequence flux path if present. The approach presented here is based on deriving an analytical expression relating the amount of inrush current reduction directly to the neutral resistor size. Investigation in this field has been done and some formulas were given to predict the general wave shape or the maximum peak current.A. Expression for magnitude of inrush currentIn Fig. 2(a), p r and p l present the total primary side resistance and leakage reactance. c R shows the total transformer core loss. Secondary side resistance sp r and leakage reactance sp l as referred to primary side are also shown. P V and s V represent the primary and secondary phase to ground terminal voltages, respectively.During first phase energizing, the differential equation describing behaviour of the transformer with saturated ironcore can be written as follows:()())sin((2) (1)φω+⋅⋅=⋅+⋅+⋅+=+⋅+⋅+=t V (t)V dtdi di d λdt di l (t)i R r (t)V dt d λdt di l (t)i R r (t)V m P ll p pp n p P p p p n p PAs the rate of change of the flux linkages with magnetizing current dt d /λcan be represented as an inductance equal to the slope of the i −λcurve, (2) can be re-written as follows;()(3) )()()(dtdi L dt di l t i R r t V lcore p p P n p P ⋅+⋅+⋅+=λ (4) )()(L core l p c l i i R dtdi−⋅=⋅λ⎩⎨⎧==sml core L L di d L λλ)(s s λλλλ>≤The general solution of the differential equations (3),(4) has the following form;⎪⎩⎪⎨⎧>−⋅⋅+−⋅+−−⋅+≤−⋅⋅+−⋅+−⋅=(5) )sin(//)()( )sin(//)(s s 22222221211112121111λλψωττλλψωττt B t e A t t e i A t B t e A t e A t i s s pSubscripts 11,12 and 21,22 denote un-saturated and saturated operation respectively. The parameters given in the equation (5) are given by;() )(/12221σ⋅++⎟⎟⎠⎞⎜⎜⎝⎛⋅−++⋅=m p c p m n p c m m x x R x x R r R x V B()2222)(/1σ⋅++⎟⎟⎠⎞⎜⎜⎝⎛⋅−++⋅=s p c p s n p c s m x x R x x R r R x V B⎟⎟⎟⎟⎟⎠⎞⎜⎜⎜⎜⎜⎝⎛⋅−+++=⋅−−⎟⎟⎟⎠⎞⎜⎜⎜⎝⎛−c p m n p m p c m R x x R r x x R x σφψ111tan tan ⎟⎟⎟⎟⎟⎠⎞⎜⎜⎜⎜⎜⎝⎛⋅−+++=⋅−−⎟⎟⎟⎠⎞⎜⎜⎜⎝⎛−c p s n p s p c m R R r x x R x σφψ112tan tan )sin(111211ψ⋅=+B A A )sin(222221s t B A A ⋅−⋅=+ωψ mp n p m p m p m p c xx R r x x x x x x R ⋅⋅+⋅−⋅+−⋅+⋅⋅⋅=)(4)()(21211σστm p n p m p m p m p c xx R r x x x x x x R ⋅⋅+⋅−⋅++⋅+⋅⋅⋅=)(4)()(21212σστ s p n p s p s p s p xx R r x x x x x x c R ⋅⋅+⋅−⋅+−⋅+⋅⋅⋅=)(4)()(21221σστ sp n p s p s p sp c xx R r x x x x x x R ⋅⋅+⋅−⋅++⋅+⋅⋅⋅=)(4)()(21222σστ ⎟⎟⎠⎞⎜⎜⎝⎛−⋅==s rs s ri i λλλ10 cnp R R r ++=1σ21221112 , ττττ>>>>⇒>>c R , 012≈A , 022≈A According to equation (5), the required inrush waveform assuming two-part segmented i −λcurve can be calculated for two separate un-saturated and saturated regions. For thefirst unsaturated mode, the current can be directly calculated from the first equation for all flux linkage values below the saturation level. After saturation is reached, the current waveform will follow the second given expression for fluxlinkage values above the saturation level. The saturation time s t can be found at the time when the current reaches the saturation current level s i .Where m λ,r λ,m V and ωare the nominal peak flux linkage, residual flux linkage, peak supply voltage and angular frequency, respectivelyThe inrush current waveform peak will essentially exist during saturation mode of operation. The focus should be concentrated on the second current waveform equation describing saturated operation mode, equation (5). The expression of inrush current peak could be directly evaluated when both saturation time s t and peak time of the inrush current waveform peak t t =are known [9].(10))( (9) )(2/)(222222121//)()(2B eA t e i A peak peak t s t s n peak n n peak R I R R t +−⋅+−−⋅+=+=ττωψπThe peak time peak t at which the inrush current will reachits peak can be numerically found through setting the derivative of equation (10) with respect to time equal to zero at peak t t =.()(11) )sin(/)(022222221212221/ψωωττττ−⋅⋅⋅−−−⋅+−=+−⋅peak t s t B A t te A i peak s peakeThe inrush waveform consists of exponentially decaying'DC' term and a sinusoidal 'AC' term. Both DC and AC amplitudes are significantly reduced with the increase of the available series impedance. The inrush waveform, neglecting the relatively small saturating current s i ,12A and 22A when extremely high could be normalized with respect to theamplitude of the sinusoidal term as follows; (12) )sin(/)()(2221221⎥⎦⎤⎢⎣⎡−⋅+−−⋅⋅=ψωτt t t e B A B t i s p(13) )sin(/)()sin()( 22221⎥⎦⎤⎢⎣⎡−⋅+−−⋅⋅−⋅=ψωτωψt t t e t B t i s s p ))(sin()( 2s n n t R R K ⋅−=ωψ (14) ωλλλφλφωλλφωmm m r s s t r m s mV t dt t V dtd t V V s=⎪⎭⎪⎬⎫⎪⎩⎪⎨⎧⎥⎥⎦⎤⎢⎢⎣⎡⎟⎟⎠⎞⎜⎜⎝⎛−−+−⋅=+⋅+⋅⋅==+⋅⋅=−∫(8) 1cos 1(7))sin((6))sin(10The factor )(n R K depends on transformer saturation characteristics (s λand r λ) and other parameters during saturation.Typical saturation and residual flux magnitudes for power transformers are in the range[9]; .).(35.1.).(2.1u p u p s <<λ and .).(9.0.).(7.0u p r u p <<λIt can be easily shown that with increased damping 'resistance' in the circuit, where the circuit phase angle 2ψhas lower values than the saturation angle s t ⋅ω, the exponential term is negative resulting in an inrush magnitude that is lowerthan the sinusoidal term amplitude.B. Neutral Grounding Resistor SizingBased on (10), the inrush current peak expression, it is now possible to select a neutral resistor size that can achieve a specific inrush current reduction ratio )(n R α given by:(15) )0(/)()(==n peak n peak n R I R I R α For the maximum inrush current condition (0=n R ), the total energized phase system impedance ratio X/R is high and accordingly, the damping of the exponential term in equation (10) during the first cycle can be neglected; [][](16))0(1)0()0(2212=⋅++⎥⎦⎤⎢⎣⎡⋅−+===⎟⎟⎠⎞⎜⎜⎝⎛+⋅⋅n s p c p s pR x n m n peak R x x R x x r R K V R I c s σ High n R values leading to considerable inrush current reduction will result in low X / R ratios. It is clear from (14) that X / R ratios equal to or less than 1 ensure negative DC component factor ')(n R K ' and hence the exponential term shown in (10) can be conservatively neglected. Accordingly, (10) can be re-written as follows;()[](17) )()(22122n s p c p s n p R x m n n peak R x x R x x R r V R B R I c s σ⋅++⎥⎦⎤⎢⎣⎡⋅−+=≈⎟⎟⎠⎞⎜⎜⎝⎛+⋅Using (16) and (17) to evaluate (15), the neutral resistorsize which corresponds to a specific reduction ratio can be given by;[][][](18) )0()(1)0( 12222=⋅++⋅−⋅++⋅−+⋅+=⎥⎥⎦⎤⎢⎢⎣⎡⎥⎥⎦⎤⎢⎢⎣⎡=n s p c p s p n s p c p s n p n R x x R x x r R x x R x x R r R K σσα Very high c R values leading to low transformer core loss, it can be re-written equation (18) as follows [9]; [][][][](19) 1)0(12222s p p s p n p n x x r x x R r R K +++++⋅+==α Equations (18) and (19) reveal that transformers require higher neutral resistor value to achieve the desired inrush current reduction rate. IV. A NALYSIS OF SECOND-P HASE E NERGIZING It is obvious that the analysis of the electric and magnetic circuit behavior during second phase switching will be sufficiently more complex than that for first phase switching.Transformer behaviour during second phase switching was served to vary with respect to connection and core structure type. However, a general behaviour trend exists within lowneutral resistor values where the scheme can effectively limitinrush current magnitude. For cases with delta winding or multi-limb core structure, the second phase inrush current is lower than that during first phase switching. Single phase units connected in star/star have a different performance as both first and second stage inrush currents has almost the same magnitude until a maximum reduction rate of about80% is achieved. V. NEUTRAL VOLTAGE RISEThe peak neutral voltage will reach values up to peak phasevoltage where the neutral resistor value is increased. Typicalneutral voltage peak profile against neutral resistor size is shown in Fig. 6- Fig. 8, for the 225 KVA transformer during 1st and 2nd phase switching. A del ay of 40 (ms) between each switching stage has been considered. VI. S IMULATION A 225 KVA, 2400V/600V, 50 Hz three phase transformer connected in star-star are used for the simulation study. The number of turns per phase primary (2400V) winding is 128=P N and )(01.0pu R R s P ==, )(05.0pu X X s P ==,active power losses in iron core=4.5 KW, average length and section of core limbs (L1=1.3462(m), A1=0.01155192)(2m ), average length and section of yokes (L2=0.5334(m),A2=0.01155192)(2m ), average length and section of air pathfor zero sequence flux return (L0=0.0127(m),A0=0.01155192)(2m ), three phase voltage for fluxinitialization=1 (pu) and B-H characteristic of iron core is inaccordance with Fig.3. A MATLAB program was prepared for the simulation study. Simulation results are shown in Fig.4-Fig.8.Fig. 3.B-H characteristic iron coreFig.4. Inrush current )(0Ω=n RFig.5. Inrush current )(5Ω=n RFig.6. Inrush current )(50Ω=n RFig.7. Maximum neutral voltage )(50Ω=n RFig.8. Maximum neutral voltage ).(5Ω=n RFig.9. Maximum inrush current in (pu), Maximum neutral voltage in (pu), Duration of the inrush current in (s)VII. ConclusionsIn this paper, Based on the sequential switching, presents an analytical method to select optimal neutral grounding resistor for transformer inrush current mitigation. In this method, complete transformer model, including core loss and nonlinearity core specification, has been used. It was shown that high reduction in inrush currents among the three phases can be achieved by using a neutral resistor .Other work presented in this paper also addressed the scheme's main practical limitation: the permissible rise of neutral voltage.VIII.R EFERENCES[1] Hanli Weng, Xiangning Lin "Studies on the UnusualMaloperation of Transformer Differential Protection During the Nonlinear Load Switch-In",IEEE Transaction on Power Delivery, vol. 24, no.4, october 2009.[2] Westinghouse Electric Corporation, Electric Transmissionand Distribution Reference Book, 4th ed. East Pittsburgh, PA, 1964.[3] K.P.Basu, Stella Morris"Reduction of Magnetizing inrushcurrent in traction transformer", DRPT2008 6-9 April 2008 Nanjing China.[4] J.H.Brunke, K.J.Frohlich “Elimination of TransformerInrush Currents by Controlled Switching-Part I: Theoretical Considerations” IEEE Trans. On Power Delivery, Vol.16,No.2,2001. [5] R. Apolonio,J.C.de Oliveira,H.S.Bronzeado,A.B.deVasconcellos,"Transformer Controlled Switching:a strategy proposal and laboratory validation",IEEE 2004, 11th International Conference on Harmonics and Quality of Power.[6] E. Andersen, S. Bereneryd and S. Lindahl, "SynchronousEnergizing of Shunt Reactors and Shunt Capacitors," OGRE paper 13-12, pp 1-6, September 1988.[7] Y. Cui, S. G. Abdulsalam, S. Chen, and W. Xu, “Asequential phase energizing method for transformer inrush current reduction—part I: Simulation and experimental results,” IEEE Trans. Power Del., vol. 20, no. 2, pt. 1, pp. 943–949, Apr. 2005.[8] W. Xu, S. G. Abdulsalam, Y. Cui, S. Liu, and X. Liu, “Asequential phase energizing method for transformer inrush current reduction—part II: Theoretical analysis and design guide,” IEEE Trans. Power Del., vol. 20, no. 2, pt. 1, pp. 950–957, Apr. 2005.[9] S.G. Abdulsalam and W. Xu "A Sequential PhaseEnergization Method for Transformer Inrush current Reduction-Transient Performance and Practical considerations", IEEE Transactions on Power Delivery,vol. 22, No.1, pp. 208-216,Jan. 2007.。

MEWS评分在急诊留观患者护理决策中的作用分析

MEWS评分在急诊留观患者护理决策中的作用分析一、MEWS评分的概念简化急诊患者危重度评估（Modified Early Warning Score，MEWS）是一种通过观察生命体征来评估患者病情变化的评分系统。

MEWS评分包括呼吸频率、心率、收缩压、体温和意识状态五个指标，通过对这些指标进行评分，并将评分结果相加，来评估患者的病情变化程度。

当评分结果高于一定阈值时，就需要及时采取相应的护理措施，以避免患者病情的进一步恶化。

MEWS评分系统简单易行、操作方便，因此在临床中得到了广泛的使用。

二、MEWS评分在急诊留观患者护理决策中的作用1. 及时发现患者病情变化在急诊留观患者的护理过程中，患者病情的变化可能随时发生，而且有些变化可能相当微弱，容易被忽略。

通过对患者进行定期的MEWS评分，可以及时监测患者的生命体征指标，并将评分结果及时记录在案。

一旦发现患者的MEWS评分升高，就可以及时采取护理措施，以防止患者病情的进一步恶化。

MEWS评分在急诊留观患者护理决策中可以起到及时发现患者病情变化的作用。

2. 提高护理质量MEWS评分可以帮助医护人员及时发现患者的病情变化，有利于提高护理质量。

通过对患者进行定期的MEWS评分，可以及时发现患者的病情变化，及时采取相应的护理措施，有利于减少医疗事故的发生，提高医疗质量和护理效果。

3. 促进医护人员间的交流在急诊留观患者的护理决策中，医护人员之间的交流配合是至关重要的。

通过对患者进行定期的MEWS评分，可以使医护人员更好地了解患者的病情变化情况，并及时进行交流，共同制定护理方案，有利于提高医护人员之间的沟通和配合，促进医护团队的协作效率。

三、MEWS评分在急诊留观患者护理决策中的局限性1. 评分标准不够客观MEWS评分系统主要通过对患者的生命体征指标进行评分，存在一定的主观性。

不同的医护人员可能会对患者的生命体征指标进行评判时存在主观性，因此可能会对评分结果产生一定的误差。

TTI逆时偏移技术在盐下成像中的应用

一
据集。文中首先运用易于处理的２Ｔ合成数据集ＤＴＩ
来证明在盐下成像时忽视ｒｒ影响会造成的错误，ｒＩ
井源距ＶＰＳ数据（能够用于约束各向异性参数）影响了在该地区对ｒＩｒ成像法的使用。ｒ
太稳定，计算量大。令人遗憾的是，在像墨西哥湾盐篷这样的复杂上覆岩层下的构造成像中，于射线基的算法与基于波动理论的算法相比，其构造成像的
效果并不好。不过，由于缺少合适的校验炮和非零
ＺａｇＺａｇ２０）ｈｎ和ｈｎ（０８针对复杂构造成像开发出了种稳定的ＴＩＴＴＭ算法。将ＴＩＴＲＴ和ＲＭ技术结合起来处理在墨西哥湾深海区域采集的几个ＷＡＺ数
１２Ｔ中综合研究：退微盆地的ＤＴＩ盐
ＴＩ应Ｔ效
２Ｔ模型包括水、Ｄ１１ＩＩ盐上、和盐下４主要单盐个元。水和盐是各向同性的，速度为常数。盐上层其与盐下层是具有垂直于沉积层面倾斜轴的１Ｉ介Ｔ ’ Ｉ
于波动理论、以解双程波动方程、可提供解释剧烈横向速度变化方法的算法，成像上却不必非要有倾在角上的限制。由于盐下成像质量的显著进步，ＴＲＭ成为盐下成像的优选算法，速替代了传统的单程迅波动方程偏移算法。然而，期的ＲＭ应用程序仅早Ｔ
计算成本也很小。与基于射线的算法不同，于波基动理论算法的阿难以公式化，运用起来经常不且

SPEI和植被遥感信息监测西南地区干旱差异分析

农业机械学报第51卷第12期2020年12月doi：10.6041/j.issn.1000-1298.2020.12.020SPEI和植被遥感信息监测西南地区干旱差异分析史晓亮吴梦月丁皓（西安科技大学测绘科学与技术学院，西安710054）摘要：基于西南地区2000—2018年不同时间尺度的标准化降水蒸散指数（SPEI1、SPEI3、SPEI12）,应用线性趋势法和曼肯德尔检验（Mann-Kendall test,M K）法分析了西南地区气象干旱的时间变化特征，评价了日光诱导叶绿素荧光（SIF）、归一化植被指数（NDVI）以及增强型植被指数（EVI）等植被遥感数据对区域植被状况监测的有效性及差异性。

结果表明：2000—2018年西南地区SPEI整体上呈微弱增加趋势，其中,2000—2013年间，SPEI12呈下降趋势（趋势率为-0.05/（10a）,R2=0.295）,2014—2018年间，SPEI12时间序列呈上升趋势（趋势率为0.04/（10a）,R2=0.094），说明在气候变化背景下,近年来西南地区的干旱化趋势有所缓解。

SPEI12的趋势突变点发生在2016年和2017年。

相对于植被绿度指数NDVI和EVI,SIF对植被生长季发生的长期和短期干旱事件均表现岀较大负异常，说明SIF可快速获取水分胁迫下的植被光合作用信息。

森林、农田和草地的SIF与不同时间尺度气象干旱指数的相关性均高于NDVI和EVI,SIF对森林、农田及草地植被生态系统干旱监测的敏感性优于传统的植被绿度指数;草地的SIF与SPEI1的相关性更高（R=0.859,P<0.01）,其光合作用对短期水分胁迫最为敏感。

本研究可为西南地区干旱的综合应对、水资源管理调控及生态治理提供科学依据。

关键词：干旱；标准化降水蒸散指数；日光诱导叶绿素荧光；遥感；西南地区中图分类号：S423；S127文献标识码：A文章编号：1000-1298（2020）12_0184_09OSID：普Difference Analysis of SPEI and Vegetation Remote SensingInformation in Drought Monitoring in Southwest ChinaSHI Xiaoliang WU Mengyue DING Hao(College of Geomatics,Xi'an University of Science and Technology,Xi'an710054,China) Abstract:Since2000,drought has occurred frequently in Southwest China,which has seriously affected social production and ecological environment.Therefore，studying the temporal evolution characteristics of meteorological drought and its impact on vegetation growth can provide theoretical basis for scientific management of regional water resources and ecological control.Based on the monthly precipitation and temperature data of Southwest China from2000to2018,the standardized precipitation evapotranspiration index of different time scales was calculated.The linear trend method and Mann Kendall(M K)test were used to analyze the temporal variation characteristics of meteorological drought in Southwest China.The effectiveness and difference of solar-induced chlorophyll fluorescence(SIF),normalized differential vegetation index(NDVI)and enhanced vegetation index(EVI)in vegetation stress monitoring were evaluated.Furthermore，the response of vegetation to drought was also explored.The results showed that SPEI values showed a weak increasing trend in all time scales from2000to2018.From2000to2013, SPEI12showed a downward trend(the trend rate was-0.05/(10a),R2=0.295),and from2014to 2018,SPEI12time series showed an increasing trend(the trend rate was0.04/(10a),R2=0.094), indicating that the drought trend in Southwest China was alleviated in recent years under the background of climate change.The turning point of SPEI12time series occurred in2016and2017respectively.Compared with NDVI and EVI，SIF showed obvious negative anomalies for both long-term and short-term drought events during vegetation growing season，and it can quickly obtain the information of vegetation photosynthesis under water stress.The correlation between SIF of forest，farmland and grassland and meteorological drought index at different time scales was higher than NDVI and EVI，which meant that 收稿日期：20200822修回日期：20200923基金项目：国家自然科学基金项目(52079103)作者简介：史晓亮(1985—)，男，副教授，博士，主要从事资源环境遥感研究,E-mail：s_xiaoliang@第12期史晓亮等：SPEI和植被遥感信息监测西南地区干旱差异分析185the sensitivity of SIF of forest,farmland and grassland vegetation ecosystem to drought monitoring was better than that of traditional vegetation greenness index.The correlation between SIF of grassland and SPEI—1was higher(R=0.859,P<0.01),which indicated the grassland photosynthesis was more sensitive to short-term water stress.The research results can provide scientific basis for comprehensive drought coping，water resources management and ecological control in Southwest China.Key words:drought;standardized precipitation evapotranspiration index；solar-induced chlorophyll fluorescence；remote sensing；Southwest China0引言干旱是一种由于长期缺乏降水或降水偏少引发供求失衡的水分短缺现象,是全球范围内最复杂、最常见的自然灾害之一⑴。

文献翻译-用磁轴承预紧的直线电机

Linear motor with magnetic bearing preloadAbstract: A positioning table includes a pair of parallel rails defining an axis of motion. A movable assembly including a first linear motor assembly disposed for motion along one of the rails. An outboard linear motor assembly on the other rail is rigidly bridged to the first linear motor assembly for concerted motion therewith. The first linear motor assembly includes a plurality of permanent magnets defining a plane at a predetermined angle to the horizontal and an armature defining a plane at the same angle closely spaced from the permanent magnets. The permanent magnets may be disposed on the movable element of the linear motor assembly or on the first rail. The armature is disposed on the other of the movable element and the first rail. First and second bearings on the movable element of the linear motor assembly, which may be air bearings support loads in the vertical and horizontal directions. The predetermined angle establishes the direction of a magnetic attractive vector between the permanent magnets and the armature. The predetermined angle is adjusted to proportion the total load of the static and dynamic load and the magnetic attractive force to a desired value. The outboard linear motor assembly on the second rail includes a plurality of permanent magnets and a second armature. The outboard linear motor assembly and the second rail may include provision for magnetic attraction at the same predetermined angle as that employed in the first linear motor assembly.Description: CROSS REFERENCE TO RELATED APPLICATIONSBACKGROUND OF THE INVENTIONThe present invention relates to linear motors and, more specifically, to apparatus for guiding and supporting a movable element of a permanent magnet linear motor in a machine tool. Linear motors conventionally are used in applications requiring the application of modest force along a linear axis. One application, disclosed in US Pat. No. 4,595,870, for example, includes driving one axis of a positioning table for displacing a work piece along the axis. Such applications are characterized by high precision in positioning, and modest force and acceleration requirements. The linear motor eliminates the windup characteristic of ball-screw drives and substantially reduces the mass of the moving element.。

通用电气绿带DOE读本

– Resolution V designs have main effects confounded with 4-factor and
higher order interactions, but not other main effects, 2- or 3-factor interactions. Two-factor interactions are confounded not with each other, but with 3-factor or higher order interactions. In other words, 2-factor interactions are clear of each other.
Higher Order Interactions
– – 1 5 16 42 99 219 466 968 • • • 32,647 • • • 1,048,365
2023/12/30
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...from a Full Factorial (4 Factors)
This can result in a large number of runs, even with a relatively small number of factors.
For a 2 level factorial with k factors…..Number of run=2k.
13
A 2-factor Experiment With Confounded Effects
Run Factor A
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交通的四种方式英语作文

When discussing the various modes of transportation,its essential to consider the different options available to individuals and how they impact our daily lives.Here are four common modes of transportation that are widely used around the world:1.Automobiles:Cars are one of the most popular means of transportation for personal use.They offer convenience,flexibility,and the ability to travel at ones own pace. However,they also contribute to traffic congestion and environmental pollution.The rise of electric vehicles is a positive shift towards reducing carbon emissions.2.Public Transportation:Buses,trains,and subways are essential for urban areas, providing a more sustainable and efficient way to move large numbers of people.Public transport systems are often more environmentally friendly than personal vehicles and can help reduce traffic.The challenge lies in ensuring that these systems are wellintegrated and accessible to all residents.3.Cycling:Bicycling is a healthy and ecofriendly mode of transportation that is gaining popularity,especially in cities with dedicated bike lanes.Its a great way to commute short distances and can also be a leisure activity.The rise of bikesharing programs has made cycling more accessible to the public.4.Walking:While it may seem like the simplest form of transportation,walking is often overlooked.Its an excellent way to stay fit and reduce ones carbon footprint.For short distances,walking can be the most efficient and healthconscious choice.Cities that prioritize pedestrianfriendly infrastructure encourage more walking and contribute to a healthier lifestyle.Each mode of transportation has its advantages and disadvantages,and the choice often depends on factors such as distance,time,cost,and personal preferences.As we move towards a more sustainable future,its crucial to consider the environmental impact of our transportation choices and to support the development of greener alternatives.。

2024年江苏新高考一卷英语试题.doc

2024年江苏新高考一卷英语试题2024年江苏新高考一卷英语试题及答案例：How much is the shirt?A.E19.15.B.E9.18.C.E9.15.答案是C.1.What is Kate doing?A.Boarding a flight.B.Arranging a tripC.Seeing a friend off.2.What are the speakers talking about?A.pop star.B.An old songC.A radio program3.What will the speakers do today?A.Goto an art show.B.Meet the mans aunt.C.Eat out with Mark4.What does the man want to do?A.Cancel an order.B.Ask for a receipt.C.Reschedule a delivery5.When will the next train to Bedford leave?A.At 9:45.B.At 10:15C.At 11:00.第二节 (共15小题;每小题1.5分，满分22.5分)听下面5段对话或独白。

每段对话或独白后有几个小题，从题中所给的 A 、B 、C 三个选项中选出最佳选项。

听每段对话或独白前，你将有时间阅读各个小题，每小题5秒钟;听完后，各小题将给出5秒钟的作答时间。

每段对话或独白读两遍。

听第6段材料，回答第6、7题。

6.What will the weather be like today?A.StormyB.SunnyC.Foggy7.What is the man going to do?A.Plant a tree.B.Move his carC.Check the map听第7段材料，回答第8至10题。

地球物理学新方法新技术

地球物理学新方法新技术英文回答：In recent years, there have been significant advancements in new methods and technologies in the field of geophysics. These developments have revolutionized the way we study and understand the Earth's physical properties and processes.One of the new methods that has gained popularity is seismic tomography. This technique involves using seismic waves generated by earthquakes or man-made sources to create images of the Earth's interior. By analyzing the travel times and amplitudes of these waves, scientists can map out the subsurface structures and identify geological features such as faults, magma chambers, and mineral deposits. Seismic tomography has been instrumental in improving our understanding of plate tectonics and earthquake hazards.Another exciting development is the use of remote sensing techniques for geophysical exploration. Remote sensing involves collecting data from a distance, typically using satellite imagery or aerial surveys. This approach has proven to be a valuable tool for mapping and monitoring various geophysical parameters, such as land surface temperature, vegetation indices, and soil moisture content. For example, thermal infrared remote sensing can be used to identify areas of potential geothermal energy resources by detecting temperature anomalies at the Earth's surface.Furthermore, advancements in geophysical instrumentation have greatly enhanced data collection and analysis capabilities. For instance, the development of high-resolution magnetometers has allowed for more accurate mapping of the Earth's magnetic field, which is crucial for studying processes such as plate tectonics and geomagnetic reversals. Similarly, the use of ground-penetrating radar (GPR) systems has revolutionized subsurface imaging, enabling scientists to detect buried archaeological structures, underground utilities, and even underground water resources.In addition to these new methods and technologies, computer modeling and data analysis have become indispensable tools in geophysics. Sophisticated software programs can now simulate and analyze complex geophysical processes, such as the behavior of fluids in porous media or the propagation of seismic waves through different geological formations. These models help scientists make predictions and interpret field observations more accurately.Overall, the advancements in new methods and technologies in geophysics have significantly improved our ability to study and understand the Earth's physical properties and processes. These tools have not only enhanced our scientific knowledge but also have practical applications in various fields, such as resource exploration, environmental monitoring, and hazard assessment.中文回答：近年来，地球物理学领域的新方法和新技术取得了重大进展。

地球物理研究英语作文

地球物理研究英语作文Title: Advancements in Geophysical Research。

Geophysical research plays a crucial role in understanding the Earth's structure, dynamics, and processes. With the continuous advancement in technology and methodologies, geophysical research has undergone significant developments, contributing to various fields such as geology, environmental science, and natural resource exploration. This essay will explore some of the key advancements in geophysical research and their implications.One of the notable advancements in geophysical research is the development of advanced imaging techniques such as seismic tomography and ground-penetrating radar (GPR). Seismic tomography utilizes seismic waves generated by earthquakes or controlled explosions to create detailed images of the Earth's interior. By analyzing the velocity and propagation of seismic waves, researchers can infer thedistribution of geological features such as faults, magma chambers, and variations in rock composition. This technology has revolutionized our understanding of tectonic plate movement, earthquake mechanisms, and volcanic activity.Similarly, ground-penetrating radar has emerged as a powerful tool for subsurface imaging in variousapplications ranging from archaeology to civil engineering. By transmitting electromagnetic pulses into the ground and recording the reflected signals, GPR systems can create high-resolution images of subsurface structures such as buried artifacts, archaeological sites, and underground utilities. This non-invasive technique has significantly enhanced our ability to study the Earth's subsurface without the need for destructive excavation.Another significant advancement in geophysical research is the integration of satellite-based remote sensing technologies. Satellites equipped with sensors capable of detecting electromagnetic radiation across different wavelengths have revolutionized our ability to monitorchanges in the Earth's surface and atmosphere. For example, satellite-based gravimetry allows researchers to map variations in the Earth's gravitational field with unprecedented accuracy, enabling the study of processessuch as glacier movement, groundwater depletion, andtectonic deformation.Furthermore, the development of advanced numerical modeling techniques has enabled researchers to simulate complex geophysical processes with high precision. Computational models based on principles of physics, chemistry, and fluid dynamics can simulate phenomena suchas mantle convection, magma migration, and groundwater flow. These models provide valuable insights into the behavior of Earth systems and can help predict future changes in response to natural or anthropogenic factors.In addition to technological advancements,collaborations between multidisciplinary teams have become increasingly important in geophysical research.Collaborative efforts involving geophysicists, geologists, engineers, and computer scientists have led to innovativeapproaches for data acquisition, analysis, and interpretation. By combining expertise from different fields, researchers can tackle complex problems more effectively and develop holistic solutions to real-world challenges.The implications of these advancements in geophysical research are profound. Improved understanding of theEarth's structure and processes not only enhances our knowledge of fundamental geoscience principles but also has practical applications in areas such as natural hazard assessment, resource exploration, and environmental monitoring. For example, seismic hazard maps generated from geophysical data can inform land-use planning and disaster preparedness efforts in earthquake-prone regions. Similarly, geophysical surveys play a crucial role in locating mineral deposits, groundwater resources, and hydrocarbon reservoirs, supporting sustainable development and resource management initiatives.In conclusion, geophysical research has witnessed significant advancements in recent years, driven bytechnological innovation, interdisciplinary collaboration, and the growing demand for solutions to global challenges. These advancements have expanded our understanding of the Earth's dynamics and have practical implications across various fields. As we continue to push the boundaries of geophysical exploration, it is essential to foster collaboration, invest in technology development, and promote the responsible use of geophysical data for the benefit of society and the environment.。

2024年高考英语试卷

2024年高考英语真题试卷（新高考Ⅰ卷）第二部分一、阅读(共两节，满分50分)第一节(共15小题；每小题2.5分，满分37.5分)阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项。

HABITAT RESTORATIONTEAMHelp restore and protect Marin's natural areas from the Marin Headlands to Bolinas Ridge. We'll explore beautiful park sites while conducting invasive(侵入的)plant removal, winter planting, and seed collection. Habitat Restoration Team volunteers play a vital role in restoring sensitive resources and protecting endangered species across the ridges and valleys.GROUPSGroups of five or more require special arrangements and must be confirmed in advance. Please review the List of Available Projects and fill out the Group Project Request Form.AGE, SKILLS, WHAT TO BRINGV olunteers aged 10 and over are welcome. Read our Youth Policy Guidelines for youth under the age of 15.Bring your completed V olunteer Agreement Form. V olunteers under the age of18 must have the parent /guardian approval section signed.We'll be working rain or shine. Wear clothes that can get dirty. Bring layers for changing weather and a raincoat if necessary.Bring a personal water bottle, sunscreen, and lunch.No experience necessary. Training and tools will be provided. Fulfills(满足)community service requirements.UPCOMING EVENTS1．What is the aim of the Habitat Restoration Team?A．To discover mineral resources.B．To develop new wildlife parks.C．To protect the local ecosystemD．To conduct biological research.2．What is the lower age limit for joining the Habitat Restoration Team?A．5.B．10.C．15.D．18.3．What are the volunteers expected to do?A．Bring their own tools.B．Work even in bad weather.C．Wear a team uniform D．Do at least three projects."I am not crazy, "says Dr. William Farber, shortly after performing acupuncture (针灸) on a rabbit. "I am ahead of my time. "If he seems a little defensive, it might be because even some of his coworkers occasionally laugh at his unusual methods, But Farber is certain he'll have the last laugh. He's one of a small but growing number of American veterinarians(兽医)now practicing "holistic" medicine-combining traditional Western treatments with acupuncture, chiropractic(按摩疗法)and herbal medicine Farber, a graduate of Colorado State University, started out as a more conventional veterinarian. He became interested in alternative treatments 20 years ago when he suffered from terrible back pain. He tried muscle-relaxing drugs but found little relief. Then he tried acupuncture, an ancient Chinese practice, and was amazed that he improved after two or three treatments. What worked on a veterinarian seemed likely to work on his patients. So, after studying the techniques for a couple of years, he began offering them to pets Leigh Tindale's dog Charlie had a serious heart condition. After Charlie had a heart attack, Tindale says, she was prepared to put him to sleep, but Farber's treatments eased her dog's suffering so much that she was able to keep him alive for an additional five months And Priscilla Dewing reports that her horse, Nappy, "moves more easily and rides more comfortably" after a chiropractic adjustment.Farber is certain that the holistic approach will grow more popular with time, and if the past is any indication, he may be right: Since 1982, membership in the American Holistic Veterinary Medical Association has grown from 30 to over 700. "Sometimes it surprises me that it works so well, "he says. "I will do anything to help an animal. That's my job. "4．What do some of Farber's coworkers think of him?A．He's odd.B．He's strict C．He's brave.D．He's rude5．Why did Farber decide to try acupuncture on pets?A．He was trained in it at university.B．He was inspired by another veterinarian.C．He benefited from it as a patient.D．He wanted to save money for pet owners.6．What does paragraph 3 mainly talk about?A．Steps of a chiropractic treatment.B．The complexity of veterinarians' work.C．Examples of rare animal diseases.D．The effectiveness of holistic medicine.7．Why does the author mention the American Holistic Veterinary Medical Association?A．To prove Farber's point B．To emphasize its importance.C．To praise veterinarians.D．To advocate animal protection.Is comprehension the same whether a person reads a text onscreen or on paper? And are listening to and viewing content as effective as reading the written word when covering the same material? The answers to both questions are often "no. " The reasons relate to a variety of factors, including reduced concentration, an entertainment mindset(心态)and a tendency to multitask while consuming digital content.When reading texts of several hundred words or more, learning is generally more successful when it's on paper than onscreen. A large amount of research confirms this finding. The benefits of print reading particularly shine through when experimenters move from posing simple tasks-like identifying the main idea in a reading passage-to ones that require mental abstraction-such as drawing inferences from a text.The differences between print and digital reading results are partly related to paper's physical properties. With paper, there is a literal laying on of hands, along with the visual geography of distinct pages. People often link their memory of what they've read to how far into the book it was or where it was on the page.But equally important is the mental aspect. Reading researchers have proposed a theory called "shallowing hypothesis(假说). " According to this theory, people approach digital texts with a mindset suited to social media, which are often not so serious, and devote less mental effort than when they are reading print Audio(音频)and video can feel more engaging than text, and so university teachers increasingly tum to these technologies -say, assigning an online talk instead of an article by the same person. However, psychologists have demonstrated that when adults read news stories, they remember more of the content than if they listen to or view identical piecesDigital texts, audio and video all have educational roles, especially when providing resources not available in print. However, for maximizing leaning where mental focus and reflection are called for, educators shouldn't assume all media are the same, even when they contain identical words.8．What does the underlined phrase "shine through" in paragraph 2 mean?A．Seem unlikely to last.B．Seem hard to explain.C．Become ready to use.D．Become easy to notice.9．What does the shallowing hypothesis assume?A．Readers treat digital texts lightly.B．Digital texts are simpler to understand.C．People select digital texts randomly.D．Digital texts are suitable for social media.10．Why are audio and video increasingly used by university teachers?A．They can hold students' attentionB．They are more convenient to prepare.C．They help develop advanced skills.D．They are more informative than text.11．What does the author imply in the last paragraph?A．Students should apply multiple learning techniques.B．Teachers should produce their own teaching material.C．Print texts cannot be entirely replaced in education.D．Education outside the classroom cannot be ignored.In the race to document the species on Earth before they go extinct, researchers and citizen scientists have collected billions of records. Today, most records of biodiversity are often in the form of photos, videos, and other digital records. Though they are useful for detecting shifts in the number and variety of species in an area, a new Stanford study has found that this type of record is not perfect."With the rise of technology it is easy for people to make observations of different species with the aid of a mobile application, "said Barnabas Daru, who is lead author of the study and assistant professor of biology in the Stanford School of Humanities and Sciences. "These observations now outnumber the primary data that comes from physical specimens(标本), and since we are increasingly using observational data to investigate how species are responding to global change, I wanted to know: Are they usable?"Using a global dataset of 1. 9 billion records of plants, insects, birds, and animals, Daru and his team tested how well these data represent actual global biodiversity patterns."We were particularly interested in exploring the aspects of sampling that tend to bias(使有偏差)data, like the greater likelihood of a citizen scientist to take a picture of af lowering plant instead of the grass rightnext to it, "said Daru.Their study revealed that the large number of observation-only records did not lead to better global coverage. Moreover, these data are biased and favor certain regions, time periods, and species. This makes sense because the people who get observational biodiversity data on mobile devices are often citizen scientists recording their encounters with species in areas nearby. These data are also biased toward certain species with attractive or eye-catching features.What can we do with the imperfect datasets of biodiversity?"Quite a lot, "Daru explained." Biodiversity apps can use our study results to inform users of oversampled areas and lead them to places -and even species -that are not well-sampled. To improve the quality of observational data, biodiversity apps can also encourage users to have an expert confirm the identification of their uploaded image. "12．What do we know about the records of species collected now?A．They are becoming outdated.B．They are mostly in electronic formC．They are limited in numberD．They are used for public exhibition.13．What does Daru's study focus on?A．Threatened species.B．Physical specimens.C．Observational data D．Mobile applications14．What has led to the biases according to the study?A．Mistakes in data analysis.B．Poor quality of uploaded picturesC．Improper way of sampling.D．Unreliable data collection devices.15．What is Daru's suggestion for biodiversity apps?A．Review data from certain areas.B．Hire experts to check the records.C．Confirm the identity of the users.D．Give guidance to citizen scientists.二、第二节(共5小题；每小题2.5分，满分12.5分)（2024·新高考Ⅰ卷）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

想要了解的事物英语作文

想要了解的事物英语作文Things I Yearn to Understand The world is an intricate tapestry woven with threads of knowledge, both known and unknown. While I find myself fascinated by the vast amount of information we’ve accumulated as a species, I am acutely aware of the vast, uncharted territories of understanding that lie before me. There are several key areas that spark a deep curiosity within me, areas I yearn to explore and grasp with greater clarity. Firstly, I am captivated by the complex workings of the human mind. The brain, a three-pound universe contained within our skulls, is a marvel of intricate networks and electrochemical signals that give rise to consciousness, emotion, and behavior. How do neurons fire in symphony to create our perceptions of the world? What are the mechanisms behind memory formation and retrieval? How does our unique blend of genetics and environment shape our personalities and predispositions? Unraveling the mysteries of the mind holds the key to understanding the very essence of what makes us human. The vast universe, with its swirling galaxies, enigmatic black holes, and the tantalizing possibility of life beyond Earth, also ignites my imagination. I long to understand the fundamental laws that govern the cosmos, from the delicate dance of subatomic particles to the majestic movements of celestial bodies. What is the true natureof dark matter and dark energy, the unseen forces shaping the universe's evolution? Are we alone in this vast cosmic expanse, or does life, in all its wondrous forms, exist elsewhere? The pursuit of answers to these questions is a quest to understand our place in the grand scheme of existence. Closer to home, the interconnected web of life on our planet fascinates me. The intricate ecosystems teeming with biodiversity, the delicate balance of predator and prey, theintricate cycles of energy and nutrients - these are all testament to the awe-inspiring power of evolution and adaptation. I yearn to understand the complex interactions within these ecosystems, the delicate balance that sustains them, and the impact of human activities on this delicate web. Understanding these complexities is crucial for our responsible stewardship of the planet and the preservation of its irreplaceable biodiversity. Furthermore, I am drawn to the intricacies of human history and its impact on our present reality. From the rise and fall of civilizations to the struggles for freedom and equality, historyoffers a lens through which we can examine the triumphs and failures of humankind.I crave a deeper understanding of the forces that have shaped our social,political, and economic systems, the ideologies that have fueled conflicts and cooperation, and the enduring legacies of past events. By studying history, wecan learn from our ancestors' mistakes and successes, equipping ourselves to navigate the challenges of the present and build a better future. The ever-evolving world of technology, with its rapid advancements in artificial intelligence, biotechnology, and space exploration, also holds a powerful allure.I am driven to understand the principles behind these innovations, their potential to address global challenges, and the ethical implications that accompany them. How can we harness the power of artificial intelligence for the betterment of society while mitigating potential risks? What are the ethical considerations surrounding genetic engineering and its impact on future generations? How can space exploration contribute to scientific advancements and inspire future generations? Exploring these frontiers of technology is essential for shaping a future where innovation serves humanity and the planet. Finally, I yearn to understand the very essence of creativity and its power to inspire, challenge, and transform. From the evocative brushstrokes of a painter to the soaring melodiesof a composer, creativity speaks a universal language that transcends cultural boundaries. What are the cognitive processes that underpin artistic expression? How does creativity foster innovation and problem-solving across disciplines? How can we nurture and cultivate our own creative potential to contribute to the world in meaningful ways? Understanding the nature of creativity is key to unlockingour own potential and enriching the human experience. In conclusion, the pursuit of knowledge is a lifelong journey, an insatiable thirst for understanding that fuels my curiosity and motivates my exploration. From the inner workings of the human mind to the vast expanses of the cosmos, from the intricate web of life on Earth to the enduring legacies of human history, from the frontiers of technology to the power of creative expression - these are the areas I yearn to understand with greater depth and clarity. This quest for knowledge is not merely an academic pursuit but a fundamental aspect of what makes us human - the desire to learn, grow, and contribute to the betterment of ourselves and the world around us.。

计量经济学中英文词汇对照

Controlled experiments Conventional depth Convolution Corrected factor Corrected mean Correction coefficient Correctness Correlation coefficient Correlation index Correspondence Counting Counts Covaห้องสมุดไป่ตู้iance Covariant Cox Regression Criteria for fitting Criteria of least squares Critical ratio Critical region Critical value
Asymmetric distribution Asymptotic bias Asymptotic efficiency Asymptotic variance Attributable risk Attribute data Attribution Autocorrelation Autocorrelation of residuals Average Average confidence interval length Average growth rate BBB Bar chart Bar graph Base period Bayes' theorem Bell-shaped curve Bernoulli distribution Best-trim estimator Bias Binary logistic regression Binomial distribution Bisquare Bivariate Correlate Bivariate normal distribution Bivariate normal population Biweight interval Biweight M-estimator Block BMDP(Biomedical computer programs) Boxplots Breakdown bound CCC Canonical correlation Caption Case-control study Categorical variable Catenary Cauchy distribution Cause-and-effect relationship Cell Censoring

2024年湖北专升本英语试题

1、What is the primary purpose of the passage?A. To discuss the benefits of online learning.B. To compare traditional classrooms with virtual classrooms.C. To highlight the challenges faced by students in remote areas.D. To analyze the impact of technology on education. (答案：D)2、Which of the following statements about climate change is NOT true?A. It is caused by human activities such as burning fossil fuels.B. It leads to an increase in global temperatures.C. It has no effect on the frequency of extreme weather events.D. It poses a threat to biodiversity. (答案：C)3、The author mentions "sustainable development" in the context of discussing:A. Economic growth without environmental degradation.B. Rapid industrialization in developing countries.C. The depletion of natural resources.D. The importance of renewable energy sources. (答案：A)4、Which of the following is a strategy for improving time management skills?A. Procrastinating tasks until the last minute.B. Multitasking without prioritization.C. Setting clear goals and deadlines.D. Constantly checking social media for updates. (答案：C)5、What is the main idea of the second paragraph in the article about healthy eating?A. The importance of a balanced diet.B. The dangers of processed foods.C. The benefits of a vegan lifestyle.D. The role of exercise in weight management. (答案：A)6、Which of the following is NOT a common type of business communication?A. EmailsB. MemosC. Social media posts (personal accounts)D. Formal reports (答案：C)7、The term "globalization" refers to:A. The spread of cultural and economic influence worldwide.B. The limitation of trade to local markets.C. The decrease in international cooperation.D. The isolation of nations from global trends. (答案：A)8、Which of these is a key factor in determining the success of a marketing campaign?A. The cost of production.B. Understanding the target audience.C. The number of advertisements placed.D. The use of the latest technology in advertising. (答案：B)9、In the field of psychology, what is meant by "cognitive dissonance"?A. A state of mental confusion caused by conflicting beliefs.B. A lack of emotional response to stimuli.C. The ability to process information quickly.D. A heightened sense of awareness. (答案：A)10、Which of the following best describes the concept of "digital literacy"?A. The ability to read and write in a digital environment.B. The skill of repairing electronic devices.C. The knowledge of computer programming languages.D. The use of technology for entertainment purposes only. (答案：A)。

Correspondence should be addressed to

Running Title: Motion Processing by MST
This work was carried out as part of Christopher Pack’s dissertation research. Authors of this article are listed alphabetically. §Supported in part by the Ofﬁce of Naval Research (ONR N00014-92-J-1309, ONR N00014-951-0409, and ONR N00014-95-1-0657). ‡Supported in part by the Ofﬁce of Naval Research (ONR N00014-94-1-0597, ONR N00014-951-0409, and ONR N00014-95-1-0657). ¶Supported in part by the Air Force Ofﬁce of Scientiﬁc Research (AFOSR F49620-92-J-0334) the Defense Advanced Research Projects Agency (ONR N00014-92-J-4015), and the Ofﬁce of Naval Research (ONR N00014-91-J-4100, ONR N00014-92-J-1309, ONR N00014-94-1-0597, ONR N00014-95-1-0409, and ONR N00014-95-1-0657).
2
TTC
Heading
Department of Cognitive and Neural Systems and Center for Adaptive Systems Boston University 677 Beacon St. Boston, MA 02215 January, 1998

后向散射系数英文

后向散射系数英文English: The backscattering coefficient, also known as the backscatter coefficient or backscatter cross section, refers to the ratio of the power of electromagnetic waves scattered backwards by a target to the power of incident waves on the target. It is a crucial parameter in radar systems and remote sensing applications, as it provides valuable information about the properties of the target being observed. The backscattering coefficient is typically dependent on various factors such as the size, shape, composition, and orientation of the target, as well as the frequency and polarization of the incident waves. Understanding the backscattering coefficient can help researchers and engineers design more efficient radar systems, interpret remote sensing data more accurately, and improve target detection and classification capabilities. Overall, the backscattering coefficient plays a vital role in the field of radar technology and remote sensing, allowing for the analysis and interpretation of scattered signals for a wide range of applications.中文翻译: 后向散射系数，也称为后向散射系数或后向散射截面，指的是目标向后散射的电磁波功率与目标上入射波功率之比。

基于邻域空间模式的运动相关电位特征提取方法

基于邻域空间模式的运动相关电位特征提取方法随着科技的不断发展，我们可以利用现代技术来监测和记录人类的脑波活动。

其中，运动相关电位（MCPS）是一种常见的电生理信号，在评估运动控制和意识状态等方面具有很大的价值。

如何提取MCPS特征是研究者们作为挑战的其中之一。

本文将介绍一种基于邻域空间模式的MCPS特征提取方法。

第一步，收集脑电数据。

进行实验前，需要征求被试者的同意，并采集脑电信号。

在实验中，将会使用两个任务：“放松任务”和“精细运动任务”。

在放松任务中，被试者需要放松身体，保持安静状态；在精细运动任务中，被试者需要进行精细手指运动，并且在完成特定的任务时，需要记录其MCPS响应。

第二步，使用邻域空间模式提取MCPS特征。

邻域空间模式是一种基于空间结构的信号处理方法，能够提供更多的空间信息。

被试者的MCPS信号会先使用人工神经网络进行降维处理，使信号转换为一个向量。

接着，利用该信号的邻域空间模式，可以计算出邻居之间的相对距离和角度，并用这些量来描述特定区域的空间特征。

最后，我们将这些空间特征与被试者的MCPS数据一起用于特征提取。

第三步，使用提取的特征进行模式识别。

利用机器学习算法，我们可以将提取的特征与标签（放松任务或精细运动任务）一起用于建立分类器。

常见的机器学习算法包括支持向量机、神经网络、随机森林等。

在此过程中，我们需要进行训练和测试以评估分类器的性能。

总的来说，以上三个步骤是基于邻域空间模式的MCPS特征提取方法的主要流程。

这种方法可以提高特征提取的准确度和鲁棒性，有助于实现MCPS特征的准确提取和分类任务的成功处理。

时空编码超表面涡旋

时空编码超表面涡旋
时空编码超表面（Spatiotemporal Encoded Metasurface，简称STEMS）是一种具有特殊电磁响应特性的人工结构表面。

涡旋（Vortex）是一种在流体、等离子体和光场等系统中广泛存在的现象，具有独特的拓扑性质。

时空编码超表面涡旋是指在时空编码超表面上产生的涡旋现象。

这种现象通常通过调整超表面的电磁参数来实现。

在时空编码超表面上，涡旋表现为表面电流或表面电磁场的分布特征。

由于时空编码超表面的独特性质，涡旋现象在光子学、等离子体物理学、流体力学等领域具有重要的研究和应用价值。

时空编码超表面涡旋的应用举例：
1. 光学：涡旋光束在光学通信、光学陷阱、光学传感和光学镊子等领域具有广泛应用。

2. 流体力学：涡旋在流体力学中起着关键作用，如旋涡脱落、湍流生成等，对流体的稳定性、传热和传质过程产生影响。

3. 等离子体：等离子体涡旋在等离子体物理、空间物理学和能源领
域具有重要作用，如磁约束聚变、太阳能电池等。

4. 天文学：在天文学中，涡旋现象在星系形成和演化过程中起到关键作用，如恒星的形成和银河系的演化。

5. 无线通信：时空编码超表面可以用于实现高效的无线通信技术，如空间复用、波束成形和指向性天线等。

总之，时空编码超表面涡旋是一种具有广泛研究和应用前景的现象，其在多个领域都发挥着重要作用。