Measurement Interpretation and Uncertainty Resulting from Nonlinear Ultrasonic Wave Propagation

Nominally identical ceramic-element ultrasonic transducers, of the type used in the aerospace and metals industries for nondestructive evaluation (NDE), often have variability in the peak pressure of the generated ultrasonic pulses. The generated pressures are also high enough for nonlinear propagation to be present in the water medium, often used as coupling in these types of inspections. In this study, a measurement system for monitoring ultrasonic pulse pressure level and nonlinear propagation in water is presented. Several different industrial NDE measurement applications are examined to quantify the impact of variable pressure and nonlinear propagation with respect to test interpretation and measurement uncertainty. In particular, pulse frequency content, velocity measurements, reference block calibrations, and beam-width measurements are examined. In addition, an experimental demonstration of why nonlinear pulse distortion is not normally observed in practice is presented.     

On the flicker noise of ferrite circulators for ultra-stable oscillators

The flicker noise of the ferrite circulator is a critical element in ultra-stable microwave oscillators, in which the signal reflected from the input of the reference cavity is exploited to stabilize the frequency. This paper explains why the circulator noise must be measured in isolation mode, proposes a measurement scheme, and provides experimental results. The observed flicker spans from -162 to -170 dB[rad2]/Hz at 1 Hz off the 9.2 GHz carrier, and at +19 dBm of input power. In the same conditions, the instrument limit is below -180 dB[rad2]/Hz. Experiments also give information on the mechanical stability of the microwave assembly, which is in the range of 10(-11) m. The measurement method can be used as the phase detector of a corrected oscillator; and, in the field of solid-state physics, it can be used for the measurement of random fluctuations in magnetic materials.     

Core memories: The perennial leader

An historical survey of the memory industry is given, and the progress of the ferrite core memory since it was first introduced is examined. It is shown that the computer industry could not have developed without a reliable and relatively cheap storage element capable of being produced in great quantity. The core memory satisfied this requirement but appeared to be vulnerable to competition by technologies more suited to mass production. The reasons why core memories have not been supplanted are examined, and a forecast for the next ten years is presented. The prediction is that core memories will retain the largest share of dollar-volume in on-line memory industry for the duration of this period.     

On measurement and valuation of manufacturing flexibility

The concept of flexibility has been a recurring theme in recent manufacturing literature. Manufacturing flexibility is widely acclaimed as a formidable competitive weapon in the arsenal of any manufacturing firm. Yet critical underpinnings of this concept are not well understood despite efforts by various researchers to classify different flexibility types in order to facilitate its measurement and valuation. This paper examines reasons why measurement of flexibility has remained difficult. It proposes that any measure must inevitably depend on factors such as the degree of uncertainty in the environment, management objectives, machine capabilities and configuration (control). Therefore it advocates surrogate measures such as the value of flexibility. A model illustrating how flexibility might be measured and its appropriate level chosen, in a specific scenario, is presented. Numerical examples reveal additional insights that might be useful to firms with characteristics that match those of the model.     

基于遗传算法和自适应的平面线轮廓度误差评定方法

 为了解决在测量平面线轮廓度中由于存在被测轮廓与其测量基准间存在位置误差而影响评定精度的问题，提出了一种基于遗传算法和自适应的计算平面线轮廓度误差的新方法。该方法满足最小条件原理，它利用样条插值函数拟合理论轮廓，并在评定过程中能自动地实现被测轮廓与理论轮廓之间的适应性调整，从而能够分离并消除被测轮廓与其测量基准之间的位置误差对轮廓误差评定结果的影响，在遗传优化中获得全局最优解。实例计算验证了这一结果。这种算法简单明确，具有精度高、收敛速度快、易于计算机程序实现、易于推广应用等特点。     

Generalized model of the quantization error-a unified approach

The effective resolution of AD converters is a crucial quantization quality parameter in modern instrumentation. A usual theoretical assumption about the quantized (training) signal is that it is a pure sine wave with a “zero” offset. This means that either the average value of the sine wave is equal to one of the threshold levels (quantizer without dead zone) or that it lies exactly in the middle of them (rounding quantizer). In the measurement technique this assumption is hardly fulfilled, and that is why we meet something intermediate between the above-mentioned hypothetical situations. Here we generalize the known results for “zero” offset to the case of unknown offset. A general problem of an arbitrary random offset distribution is considered first. Two important practical cases are then analyzed. The first one is an unknown and nonrandom offset (one-point distribution). The second one is a case of a uniform distribution of the offset (effect of dithering on quantizer input). In particular, the expected values and variances are derived and analyzed versus the offset and the number of quantizing levels. The results obtained are applied to the effective resolution measurement     

Effects of non-Lambertian surfaces on integrating sphere measurements

The effects of non-Lambertian scattering of the interior wall of an integrating sphere are examined through a sphere simulation model. The model employs Monte Carlo techniques. A sphere used for measurement of directional-hemispherical reflectance is modeled. The simulation allows sphere wall scattering to vary from perfectly Lambertian to perfectly specular in steps. The results demonstrate that significant measurement error can result as the scattering deviates from the Lambertian ideal. The error is found to be a strong function of the wall reflectance value as well: it is minimized for reflectances approaching 1.0 and increases as the reflectance value decreases to the minimum value examined of 0.5. The magnitudes of the errors associated with non-Lambertian scattering are also shown to be relatively independent of the specific field of view of the detector used in the measurement.     

A Full Fingerprint Verification System for a Single-Line Sweep Sensor

This paper presents a full fingerprint verification system. It is composed of a tactile fingerprint sensor, integrated read out and conversion circuits, and dedicated recognition algorithms. The sensor is a single-line sweep mode sensor, e.g., it is made of a single line of sensing elements, thus covering the minimum surface of silicon. Compared with cm² sized touch sensors, it offers a large cost reduction and possibility of easy integration into portable devices. The use of a single line to measure a fingerprint requires the user to sweep its finger along the sensor. This sensing scheme produces fingerprint images with several distortions that needs further image processing to allow efficient fingerprint recognition. This is why we developed and present here specific algorithms to take care of the sensor's specifications. This paper will present measurement results, as well as a performance evaluation of the entire verification system.     

发射率对半导体器件显微红外测温结果的影响

为了确认半导体器件较低的发射率对显微红外测温结果的影响,采用研制的半导体材料和金属材料靶标进行了一系列验证实验,分析了发射率对显微红外热像仪测温准确度的影响.研制了带有铂电阻结构的GaAs材料靶标和Au材料靶标,用显微红外热像仪对黑体和研制的2种靶标进行了不同温度下的测试,在110℃条件下,黑体、GaAs、Au 3种材...     

Comparative Analysis of Different Air Density Equations

In general mass measurements are carried out in air and that’s why air buoyancy correction plays a major role in mass measurements and it is totally dependent on density of air of the laboratory during the measurement. The density of air is calculated from temperature, relative humidity, air pressure, concentration of CO₂ monitored (for CIPM formula only) in the laboratory rather direct determination and for calculation of density of air, CIPM-2007 formula is recognized as most accurate formula. Since CIPM formula is very complicated formula and it is not required for less accurate measurements, different National Metrology Institutes have derived simple equations to calculate air density and those are known as approximation formulas. We had gone through a comparative analysis among different formulas of density of air to evaluate which approximation formula is most accurate compare to CIPM-2007 formula.     

Hierarchies, Markets and Power in the Economy : An Economic Perspective

This paper adopts the transaction cost economics perspectivefor purposes of examining hierarchies, markets, and power inthe economy. Transaction cost economics works out of an economizingperspective in which markets and hierarchies are alternativemodes of governance and the object is to ascertain which transactionsgo where and why. The role of power in this setup is strictlylimited—partly because power tends to be myopic (transactionsare not examined ‘in their entirety’) and partlybecause it is tautological. Power needs to be optrationalized,whereupon the refutable implications that accrue to this perspectivecan be derived.     

„In Stockholm hatte man offenbar irgendwelche Gegenbewegung” – Ferdinand Sauerbruch (1875–1951) und der Nobelpreis

The archive of the Nobel Assembly for Physiology or Medicine in Solna, Sweden, is a remarkable repository that contains reports and dossiers of the Nobel Prize nominations of senior and junior physicians from around the world. Although this archive has begun to be used more by scholars, it has been insufficiently examined by historians of surgery. No other German surgeon was nominated as often as Ferdinand Sauerbruch for the Nobel Prize for Physiology or Medicine in the first half of the 20th century. This contribution reconstructs why and by whom Sauerbruch was nominated, and discusses the Nobel committee evaluations of his work. Political factors did not play an obvious role in the Nobel committee discussions, in spite of the fact that Adolf Hitler in 1937 had prohibited all German citizens to accept the Nobel Prize. The main reasons why Sauerbruch ultimately was not considered prize-worthy were that Sauerbruch’s achievements were marked by scientific priority disputes, and that his work was not seen as original enough.     

Fit analysis in latent trait measurement models

The analysis of fit, whether viewed from the prospective of the fit of the data to the measurement model, or the fit of the measurement model to the data, is an important part of using latent trait models. In the case of the Rasch model, all of the desirable characteristics of the model (interval item and person measures, asymptotic standard errors, parameter invariance across subsets of persons or items, to name a few) are predicated on the requirement that the data fit the model. To the extent that the data do not fit the model, these properties hold to a lesser degree. The analysis of fit is of primary importance if the interpretation of the calibration results is to be useful. This article explores the nature of fit and provides a historical overview of fit indices. It then focuses on a particular family of fit indices that are based on the Pearsonian chi-square approach to fit, in an attempt to show why it is necessary to use a family of standardized fit indices to completely understand the relationship between the data and the model.     

The Use of a Second Harmonic Correlation to Detect Damage in Composite Structures Using Thermoelastic Stress Measurements

Abstract: A novel development of the thermoelastic stress measurement technique using the second harmonic of the load test frequency is presented. Clear identification of significant sub-surface damage is demonstrated using the new technique, and test results are presented from a small scale wind turbine blade test which indicate that some quantitative assessment of damage criticality might be possible from a single full-field measurement. A hypothesis is presented as to why the new technique is successful, based on complex movements of the surface caused by local buckling (itself a consequence of the sub-surface damage). Strain gauge evidence is presented to support this hypothesis.     

Study of the measurement of the transverse emittances of a beam by the three gradients method: Application to the case of a focusing by solenoid

Within the framework of the ALTO project (Linear Accelerator near the Orsay Tandem), IPN Orsay will use NEPAL facility of LAL as the ALTO injector. In order to calculate the beam optics of the linear accelerator, it is necessary to find out the electrons beam emittance at the exit of the buncher station.

According to previous studies there are several methods for measuring this emittance: direct methods like the Pepper Pot technique, and indirect ones namely the three distances method and the three gradients technique. Moreover, the latter requires a variable optic element (i.e. quadrupole, solenoid…). Generally, the solenoid is used to focus the beam when the later has a symmetry axe of revolution compared to the direction of propagation and it has the same emittance in the two horizontal and vertical planes. In the case of ALTO injector, we did not have the certainty if the beam presented such symmetry. The effects of coupling introduced by the action of the solenoid were thus to be planned to determine the emittance starting from the transverse profiles measurement. This is why we developed a general method of calculation which takes into account the coupling when the horizontal and vertical emittances are different. The first part of this study is dedicated to its presentation. The second part is dedicated to the presentation of emittance measurement results obtained by using this method.     

奥氏体铸体和18—8不锈钢在烧碱中的腐蚀行为

用失重法和电化学方法研究了奥氏体铸铁的１８－８不锈钢在高温烧碱中的腐蚀行为。用扫描电镜观察了两种材料泵件表面的腐蚀形貌,分析了奥氏体铸铁耐碱腐蚀性能优于１８－８不锈钢的原因。     

激光粒度分析和筛分法测粒径分布的比较

分别采用筛分法和马尔文激光粒度分析仪两种方法对16种颗粒的粒径分布进行了测量。通过比较,发现两种测量手段得到的粒径分布结果存在较大的差异,马尔文激光粒度方法对颗粒粒径的测量结果偏小,受颗粒形状的影响很大;筛分法对微细颗粒的测量误差较大,但对大粒径颗粒的测量较为准确。通过对不同粒径段灰颗粒的显微照相,发现细颗粒的团聚是筛分法测量小颗粒结果偏小的主要原因。     

自然标记法相关流量测量的线性系统理论

人工标记法相关流量测量中的线性系统理论早已有之,但对自然标记法相关流量测量若使用相同的线性系统理论就会发现有很多矛盾之处。针对这一情况,作建立了分布式注入源的物理模型。借助这一模型,传感器信号的自相关函数（ACF）与传感器所处位置无关的原因、自然标记法相关流量测量中互相关函数（CCF）的确切含义、以及自然标记法与人工标记法在系统理论意义下的异同等,都得到了定量的解释。结论是除了自然标记法的信噪比（SNR）较人工标记法要低之外,两并无其它本质区别。