The Impact of Model Based Offset Scaling Technique on the Amplitude Variation with Offset Responses from 3D Seismic Data Acquired from the Tano Basin, Offshore Ghana

Amplitudes have been found to be a function of incident angle and offset. Hence data required to test for amplitude variation with angle or offset needs to have its amplitudes for all offsets preserved and not stacked. Amplitude Variation with Offset (AVO)/Amplitude Variation with Angle (AVA) is necessary to account for information in the offset/angle parameter (mode converted S-wave and P-wave velocities). Since amplitudes are a function of the converted S- and P-waves, it is important to investigate the dependence of amplitudes on the elastic (P- and S-waves) parameters from the seismic data. By modelling these effects for different reservoir fluids via fluid substitution, various AVO geobody classes present along the well and in the entire seismic cube can be observed. AVO analysis was performed on one test well (Well_1) and 3D pre-stack angle gathers from the Tano Basin. The analysis involves creating a synthetic model to infer the effect of offset scaling techniques on amplitude responses in the Tano basin as compared to the effect of unscaled seismic data. The spectral balance process was performed to match the amplitude spectra of all angle stacks to that of the mid (26°) stack on the test lines. The process had an effect primarily on the far (34° - 40°) stacks. The frequency content of these stacks slightly increased to match that of the near and mid stacks. In offset scaling process, the root mean square (RMS) amplitude comparison between the synthetic and seismic suggests that the amplitude of the far traces should be reduced relative to the nears by up to 16%. However, the exact scaler values depend on the time window considered. This suggests that the amplitude scaling with offset delivered from seismic processing is only approximately correct and needs to be checked with well synthetics and adjusted accordingly prior to use for AVO studies. The AVO attribute volumes generated were better at resolving anomalies on spectrally balanced and offset scaled data than data delivered from conventional processing. A typical class II AVO anomaly is seen along the test well from the cross-plot analysis and AVO attribute cube which indicates an oil filled reservoir.

基于SBAS-InSAR与Offset-Tracking的色东普流域灾前形变探究

利用SAR偏移量追踪(offset-tracking)技术获取冰川形变作为SBAS-InSAR的补充,采用2种技术计算2018-01~10色东普流域灾前形变,联合分析灾前形变特征及影响因素。结果表明,色东普流域冰川与沟道在2018-10-17冰崩灾害发生前已出现形变;冰川主要形变区形变趋势表现为加速-平缓-加速,7~9月形变量达到-7.69 m;沟道内堆积物长期呈下滑趋势,7月后与冰川均加速形变;气温升高是冰崩碎屑流灾害发生的主导因素。联合SBAS-InSAR与offset-tracking技术能够满足不同形变量级的监测需求,可用于冰崩灾害的早期识别与形变反演,为青藏高原地区冰崩灾害防治提供参考。

Permanent Magnet Temperature Estimation for PMSMs Using Virtual Position-offset Injection

This paper proposes a virtual position-offset injection based permanent magnet temperature estimation approach for permanent magnet synchronous machines(PMSMs). The concept of virtual position-offset injection is mathematically transforming the machine model to a virtual frame with a position-offset. The virtual frame temperature estimation model is derived to calculate the permanent magnet temperature(PMT) directly from the measurements with computation efficiency. The estimation model involves a combined inductance term, which can simplify the establishment of saturation compensation model with less measurements. Moreover, resistance and inverter distorted terms are cancelled in the estimation model, which can improve the robustness to the winding temperature rise and inverter distortion. The proposed approach can achieve simplified computation in temperature estimation and reduced memory usage in saturation compensation. While existing model-based approaches could be affected by either the need of resistance and inverter information or complex saturation compensation. Experiments are conducted on the test machine to verify the proposed approach under various operating conditions.

Analytical Determination of Size and Location of Roadside Horizontal Sightline Offsets for Compound Curves

AASHTO’s guideline for geometric design of highways and similar guidelines require that roadside areas on the inside of horizontal curves be cleared of high objects to provide stopping sight distance. The guidelines have analytical models for determining the extent of clearance, known as the horizontal sightline offset or clearance offset, for simple curves. Researchers in the past have developed analytical models for clearance offsets for spiraled and reverse curves. Very few researchers developed analytical models for available sight distances for compound curves. Still missing are models for horizontal sightline offsets and locations of the offsets for compound curves. The objective of this paper is to present development of analytical models and charts for determining horizontal sightline offsets and their locations for compound curves. The paper considers curves whose component arcs are individually shorter than stopping sight distance. The resulting models and the charts have been verified with accurate values determined using graphical methods. The models and the charts will find application in geometric design of highway compound curves.

Offset restoration in total hip arthroplasty:Important:A current review

Normal vertical and horizontal offset is essential for hip biomechanics,muscle functioning and gait pattern.Total hip arthroplasty(THA)should aim to restore normal offset with implantation of femoral and acetabular components.This would be possible with proper preoperative planning,templating and ensuring implant options are available for offset restoration.Templating is essential for understanding the vertical and horizontal offset change,especially in hip arthritis presenting late with significant limb length discrepancy at THA.Planning should include appropriate soft tissue releases and the use of ideal implants to achieve restoration of horizontal and vertical offset.Under correction of horizontal offset at THA for fracture neck of femur could result in abductor fatigue,limp and increased wear.Restoration of horizontal offset is imperative at THA for a fractured neck of the femur to achieve optimal abductor function.Horizontal offset is necessary for optimal abductor muscle tension and function.Revision THA for acetabular bone loss would require hip center restoration with the acetabular and femoral offset correction to achieve limb length correction and abductor length.The inability to achieve vertical and horizontal offset correction could lead to dislocation or signs of abductor fatigue.Careful vertical and horizontal femur offset restoration is required for normal hip biomechanics,decreased wear and increased longevity.

Near resonance vibration isolation on a levered-dual response(LEDAR)Coulomb-damped system by differential preloads/offsets in linear springs

The levered-dual response(LEDAR)Coulomb-damped system attains near resonant vibration isolation by differential preloads/offsets in linear springs.It takes the advantages of both the preloads/offsets in linear springs and the guiderail friction for realizing different levels of vibration isolation.The isolation capacities are investigated on the strategies with both the horizontal and vertical guiderails,with the horizontal rail only,and without guiderails.The compressive preloads generally result in the consumption of most of the initial excitation energy so as to overcome the potential threshold.The isolation onsets at the frequency ratio of 1∓0.095 on the left-hand side(LHS)and the right-hand side(RHS)of the lever are relative to the load plate connector.The observed near resonant isolation thus makes the LEDAR system a candidate for the isolation of the mechanical systems about resonance while opening a path for simultaneous harvesterisolation functions and passive functions at extreme frequencies.

The Effect of Lateral Offset Distance on the Aerodynamics and Fuel Economy of Vehicle Queues

The vehicle industry is always in search of breakthrough energy-saving and emission-reduction technologies.In recent years,vehicle intelligence has progressed considerably,and researchers are currently trying to take advantage of these developments.Here we consider the case of many vehicles forming a queue,i.e.,vehicles traveling at a predetermined speed and distance apart.While the majority of existing studies on this subject have focused on the influence of the longitudinal vehicle spacing,vehicle speed,and the number of vehicles on aerodynamic drag and fuel economy,this study considers the lateral offset distance of the vehicle queue.The group fuel consumption savings rate is calculated and analyzed.As also demonstrated by experimental results,some aerodynamic benefits exist.Moreover,the fuel consumption saving rate of the vehicle queue decreases as the lateral offset distance increases.

A Residual Frequency Offset Estimation Method Based on Range Migration Fitting

Recently,researchers have proposed an emitter localization method based on passive synthetic aperture.However,the unknown residual frequency offset(RFO)between the transmit-ter and the receiver causes the received Doppler signal to shift,which affects the localization accu-racy.To solve this issue,this paper proposes a RFO estimation method based on range migration fitting.Due to the high frequency modulation slope of the linear frequency modulation(LFM)-mod-ulation radar signal,it is not affected by RFO in range compression.Therefore,the azimuth time can be estimated by fitting the peak value position of the pulse compression in range direction.Then,the matched filters are designed under different RFOs.When the zero-Doppler time obtained by the matched filters is consistent with the estimated azimuth time,the given RFO is the real RFO between the transceivers.The simulation results show that the estimation error of azimuth distance does not exceed 20 m when the received signal duration is not less than 3 s,the pulse repe-tition frequency(PRF)of the transmitter radar signal is not less than 1 kHz,the range detection is not larger than 1000 km,and the signal noise ratio(SNR)is not less than-5 dB.

快速成型系统中OFFSET型填充算法

在SW 2 50 1快速成型系统中 ,零件的制作是靠热喷头喷出热熔丝逐层堆积成型的 ,在逐层堆积过程中 ,热喷头要做大量的填充扫描 ,填充方法直接影响零件的成型质量 .文中介绍了一种基于截面轮廓的OFFSET型填充路径的生成算法 ,该算法快速可靠 ,能得到比较光滑、平整的成型截面 .

基于控制顶点扰动的平面Offset曲线的NURBS逼近

平面曲线的ｏｆｆｓｅｔ曲线具有丰富的几何结构，它在曲面造型、ＮＣ加工等领域具有广泛应用，但除直线、圆弧或速端曲线等少数几种曲线外，有理多项式参数曲线的ｏｆｆｓｅｔ曲线不能保证仍是有理多项式曲线形式．因此，实际应用中常用逼近方法表示ｏｆｆｓｅｔ曲线，以保证造型系统中数据结构和几何算法的统一表示．作者针对平面ＮＵＲＢＳ曲线的特点，提出两种逼近表示方法，一种是基于曲线分割的控制顶点扰动法，另一种是整体控制顶点偏移法．两种方法都可以任意控制ｏｆｆｓｅｔ曲线的逼近精度．所给出的算法简单直观，便于系统实现．经实例验证，算法稳定可靠．并在自主开发的商品化三维造型系统Ｇｅｍ ｓ５．０

平面NURBS曲线及其Offset的双圆弧逼近

除直线、圆弧、速端曲线等少数几种曲线外 ,平面参数曲线的 offset曲线通常不能表示成有理参数形式 ,因此在实际应用中 ,为了方便造型系统中数据结构和几何算法的统一表示 ,offset曲线通常用低次曲线逼近来表示 .通过用双圆弧逼近表示 NURBS( non- uniform rational B- spline)曲线及其 offset,并利用双圆弧逼近的特有性质 ,把 offset的双圆弧逼近转化为原曲线的双圆弧逼近 ,简化了问题的求解 .同时考虑了双圆弧逼近算法中分割点的选取、公切点的确定以及误差估计等主要问题 .具体算法在自主开发的 Gems5.0中实现 .经实例表明 ,算法稳定。

二维Offset平面波有限差分法叠前时间偏移

在岩性油气藏勘探中,保振幅或保波形成像是进行储层特征分析和参数估计的基础。由于Kirchhoff积分叠前时间偏移、F-K域波动方程叠前时间偏移不适应弱横向变速介质情形,因此,基于偏移距(Offset)域平面波偏移思想,提出了Offset平面波有限差分法叠前时间偏移方法。讨论了CMP道集平面波分解原理,推导了Off- set平面波方程及其有限差分解法,给出了角度道集生成方法。利用大庆油田的一个横向缓变的速度模型,对Offset平面波有限差分法叠前时间偏移方法的有效性进行了验证。结果表明,该方法适应缓横向变速介质情形,波场外推算子保幅,计算效率高,可以为AVP/AVA分析提供较好的基础数据。

多边形OFFSET中无效环的去除算法

对于多边形OFFSET后产生的自交环现象,提出一种求解自交点的基于单调链的平面扫描算法,并对环的判别提出了一种简便而有效的方法。最后,对算法的时间复杂度进行了分析。实验表明,该算法高效而稳定地处理多边形OFFSET后产生的自交环。

椭圆型Offset曲线及其应用

针对 Sweep曲面中形变控制的需要 ,提出了一种椭圆型 offset曲线 ,并讨论了它的性质 .为了便于造型系统的一致性表示 ,给出了椭圆型 offset曲线的 NURBS逼近表示算法 .最后给出了它的应用实例 ,并在自主开发的几何造型系统 GEMS 5 .0中实现 .

A Ventral Diverterless High Offset S-shaped Inlet at Transonic Speeds

An investigation on the ventral diverterless high offset S-shaped inlet is carried out at Mach numbers from 0.600 to 1.534, angles of attack from -4° to 9.4°, and yaw angles from 0° to 8°. Results indicate： （1） a large region of low total pressure exists at the lower part of the inlet exit caused by the counter-rotating vortices in the S-shaped duct; （2） the performances of the inlet at Mach number 1.000 reach almost the highest, so the propulsion system could work efficiently in terms of aerodynamics; （3） the total pressure recovery increases slowly at first and then remains unvaried as the Mach number rises from 0.6 to 1.0, however, it does in an opposite manner in the conventional diverter-equipped S-shaped inlet; （4） the performances of the inlet are generally insensitive to angles of attack from -4° to 9.4° and yaw angles from 0° to 8° at Mach number 0.850, and angles of attack from -2° to 6° and yaw angles from 0° to 5° at Mach number 1.534.

A Novel Offset-Cancellation Technique for Low Voltage CMOS Differential Amplifiers

Based on a physical understanding of nonlinearity and mismatch, a novel offset-cancellation technique for low voltage CMOS differential amplifiers is proposed. The technique transfers the offset voltage from the output to other parts of the differential amplifier and can greatly reduce the input-referred offset voltage without extra power consumption. A 1.8V CMOS differential amplifier is implemented in 0.18μm CMOS process using the proposed technique. The simulation results show that the technique could reduce the input-referred offset voltage of the amplifier by 40% with a 20% load transistor mismatch and a 10% input differential transistor mismatch. Moreover, the proposed technique consumes the least power and achieves the highest integration among various offset-cancellation techniques.

Topographic effects on long offset transient electromagnetic response

The forward modeling procedure used in this article is formulated with the volume integral equation based on the tensor Green＇s function. The electromagnetic components responses are first calculated in the frequency domain and then transformed to the time domain by digital filtering. The valley and hill topography with a layered earth is stimulated by a horizontal electric dipole （HED） transmitter, which is common in field surveys, and the TEM responses are calculated at the transmitter and receivers. The topography effects on the long offset electromagnetic transient （LOTEM） responses are discussed in detail. The results show that both valley and hill topography has significant effect on the LOTEM measurement. If the HED is located in the bottom of a valley, the distortion of the observed anomalous field at distance is severe. A valley at the receiver locations show a strong effect but are localized in space and time. In general, hill-shaped topography shows smaller effects no matter where its located. When the topography is located between source and receivers, the influence is negligible. We conclude that the location of the source is much more important than the receivers and it is critical to put the transmitter in an open flat area in the field survey.

区间 Bezier 曲线/曲面与 Offset 曲线/曲面之间的关系

本文证明了对任意已知的区间Ｂｅｚｉｅｒ曲线／曲面总存在两条／张Ｏｆｓｅｔ曲线／曲面分别包含与被包含此曲线／曲面，反之亦然。

Quadrature error and offset error suppression circuitry for silicon micro-gyroscope

The reasons for inducing quadrature error and offset error are analyzed and the expressions of quadrature error and offset error are induced. The open-loop system analysis indicates that, in order to avoid the appearance of harmonic peaks, the frequency difference δf between drive mode and sense mode must be less than 1/（2Qy）. In order to eliminate the effects of the quadrature error and the offset error, as well as the inherent non- linearity in the capacitance-type sensors, a closed-loop feedback control circuit with quadrature correction is designed. The experimental results indicate that the quadrature error and offset error are corrected. By comparing with open-loop detection, the closed-loop feedback control circuit with quadrature correction decreases the non-linearity of the scale factor from 16. 02% to 0. 35 %, widens the maximum rate capability from ± 270 （°）/s to ± 370 （°）/s and increases the stability of zero bias from 155. 2 （°）/h to 60. 6 （°）/h.

LDPC码offset BP-Based译码算法研究与硬件实现

低密度奇偶校验(Low-Density Parity-Check LDPC)码是一种接近Shannon极限的信道编码,在低信噪比的环境下仍能获得优异的误码率性能,目前应经成为编码界的热点研究课题之一。本文在探讨了LDPC码的经典BP(Belief Propaga-tion)译码算法的基础上,通过分析比较,选取一种复杂度较低,性能较好的offset BP-Based译码算法在FPGA上进行实现,验证了LDPC码的优异性能,对于译码算法的硬件实现具有指导意义。