Refining visually estimated arrival times of short duration signals

Estimating the location of a radiating source from recorded sensor signals requires accurate arrival time estimates. If the sensor signals have a short time duration, generating accurate arrival time estimates is a challenging task. This paper proposes a new cross-correlation averaging algorithm which is integrated with a visual ‘peak picking’ alignment approach to improve the estimation of the arrival times. An important application that results in short time duration signals is seismic activity in mines. This seismic activity is produced by high stress faults in the vicinity of the mining operations. Locating the source of these seismic events is important for mine safety. This paper focuses on this mining application to demonstrate how the cross-correlation averaging algorithm can improve the arrival time delay estimation and thus provide better hypocenter location estimates of seismic events in mines.     

Single photon x-ray detection with a CCD image sensor

Individual x rays of 5.9 and 22.4 keV have been detected and energy analyzed in single pixels of a CCD image sensor. The results indicate the CCD operates as an array of tiny Si solid state detectors providing both high spatial resolution and x-ray energy discrimination. These devices will prove useful sensors at the focus of future x-ray telescopes.     

Software defined photon counting system for time resolved x-ray experiments

The time structure of synchrotron radiation allows time resolved experiments with sub-100 ps temporal resolution using a pump-probe approach. However, the relaxation time of the samples may require a lower repetition rate of the pump pulse compared to the full repetition rate of the x-ray pulses from the synchrotron. The use of only the x-ray pulse immediately following the pump pulse is not efficient and often requires special operation modes where only a few buckets of the storage ring are filled. We designed a novel software defined photon counting system that allows to implement a variety of pump-probe schemes at the full repetition rate. The high number of photon counters allows to detect the response of the sample at multiple time delays simultaneously, thus improving the efficiency of the experiment. The system has been successfully applied to time resolved scanning transmission x-ray microscopy. However, this technique is applicable more generally.     

Shape measurement of long microbores applying photon counting method

New technology, especially in the field of microelectronics and mechatronics, created the need for making, positioning and inspection techniques of long microbore-holes and gaps (defined by length/width to diameter ratio l/d > 10 for d < 200 μm). The technological aspect is, in principle, subdued but the metrological one is still unsolved.In Zosel et al. [Zosel J, Guth U, Thies A, Reents B. Flow measurements in micro holes with electrochemical and optical methods. Electrochim Acta 2003;48:3299–305] the properties (power loss and phase distortion) of focused laser microbeam penetrating extremely long through microbores is described; it was proved that the measurement information is distorted depending on the microbore geometry. The samples were prepared of glass–resin laminate with microbore diameter ranging from 35 to 200 μm.In present research an adjustable 100 μm microbore is used as a master. It is formed of mutually accurately adjusted 20 metal plates 100 μm thick set of coaxially in pile. Precise positioning of each plate enables creating free-shaped microbore.The photon batching device emitting 2.5 million photons per second is used as a generator of incident photon beam. The measured transmission efficiency is understood as a relation between outgoing and incoming light energy. The outgoing energy, for particular microbore, was determined by scanning linearly and angularly the bore with photon beam and integrating the results. Experiments were performed in dark room with background 2/5 photons per second (including dark current of photomultiplier).These changes describe the relationship between the shape of the microbore and the transmission energy and can be considered as a measure of microbore cylindricity deviation.     

A small-angle scattering chamber for x-ray photon correlation spectroscopy at low temperatures

A low temperature sample environment for x-ray photon correlation spectroscopy measurements in small-angle scattering geometry is presented. The chamber has been designed to allow investigations of dynamical phenomena in supercooled liquids and the typical working temperature range is 110-330 K with a thermal stability ΔT/T down to 10(-4). A variable external magnetic field up to 0.12 T can be applied, which is of interest in studies of, e.g., ferrofluids and liquid crystalline materials. Here, technical details about the sample environment are given together with examples of recent applications.     

Portable x-ray fluorescence spectrometer for coating thickness measurement

A handheld x-ray spectrometer has been realized and tested. The purpose of the device is to measure the thickness of coated samples in the range of 1-1500 nm in an industrial environment. Accuracy of approximately 3% has been achieved in this range with a measurement time of 1 min. Automated software has been implemented to allow utilization by a nonspecialist operator. An automated calibration procedure, based on measurements of reference samples, is used.     

Continuous wear measurement by on-line ferrography

An on-line Ferrograph was used to monitor the wear rates of oil-lubricated ball-bearings. Periodically, the test bearings were also removed from the test stand and cleaned and weighed on an analytical balance.A comparison of the mass loss data obtained by each of these two methods showed that the Ferrograph readings did provide on-line quantitative wear data for each individual test. However, the rates at which the ball-bearings wore were not consistent from test to test. For the four ball-bearings that were evaluated, plots of the Ferrograph concentration readings versus bearing mass loss gave slopes that varied between 1.1 and 2.5. Nevertheless, the results showed that semiquantitative data on the wear rates of machine components could be obtained with this on-line instrumentation.     

Firmware lower-level discrimination and compression applied to streaming x-ray photon correlation spectroscopy area-detector data

We present a data acquisition system to perform on-the-fly background subtraction and lower-level discrimination compression of streaming x-ray photon correlation spectroscopy data from a fast charge-coupled device (CCD) area detector. The system is built using a commercial frame grabber with an on-board field-programmable gate array. The system is capable of continuously processing at least 60 CCD frames per second each consisting of 1024 × 1024 16-bit pixels with ? 15,000 photon hits per frame at a maximum compression factor of ≈95%.     

Design and measurement of a Cu L-edge x-ray filter for free electron laser pumped x-ray laser experiments

An inner-shell photoionized x-ray laser pumped by the Linac Coherent Light Source (LCLS) free electron laser has been proposed recently. The measurement of the on-axis 849 eV Ne?Kα laser and protection of the x-ray spectrometer from damage require attenuation of the 1 keV LCLS beam. An Al/Cu foil combination is well suited, serving as a low energy bandpass filter below the Cu L-edge at 933 eV. A high resolution grating spectrometer is used to measure the transmission of a candidate filter with an intense laser-produced x-ray backlighter developed at the Lawrence Livermore National Laboratory Jupiter Laser Facility Janus. The methodology and discussion of the observed fine structure above the Cu L-edge will be presented.     

Continuous measurement of interaction forces between wheel and rail

Oscillatory wheel load fluctuation of considerable amplitude is always observed in railway cars traveling at high speed. This paper describes a continuous method for measuring the derailment coefficient and the forces between the wheel and rail. The acceleration measured on the axle box indicates that the frequency of this fluctuation can be as high as 70 Hz. Continuous measurement of wheel load using conventional methods is not possible due to this high frequency phenomenon. We have developed a new method for continuous measurement of these forces and the derailment coefficient using two pairs of strain gauge bridges with output phases shifted by 90°, and summing their outputs with a weighting function. This method works for measuring the forces between wheel and rail at high frequencies.     

Similarity measurement of the geometry variation sequence of intermediate process model

Journal of Mechanical Science and Technology - The reuse of machining process, by which the process for a new mechanical part is determined by referencing to the existing and matured processes, is...     

基于伪随机序列调制的荧光测量系统

荧光分析法和伪随机序列技术均在多个领域有广泛应用。荧光测量过程中常伴随着复杂的背景噪声和干扰,为测量精度的提高带来了困难。利用伪随机序列的相关特性和频谱扩展效应,提出了一种适用于荧光测量系统的,基于伪随机序列的激发光调制方法。通过建立数学模型,从信号和噪声的频谱角度定量分析了伪随机序列调制系统对噪声和干扰的抑制能力,给出了序列参数与测量系统信噪比之间的关系。最后将该调制方法应用于一个典型的荧光测量系统(荧光型叶绿素仪)中。理论和实验结果都表明,使用伪随机序列调制方式能显著提高荧光检测信噪比,叶绿素仪的线性响应相关系数R2在0.999以上,达到国外同类型高端仪器水平。     

基于多层序列图像的三维表面粗糙度检测

提出了一种非接触检测工件表面粗糙度的新方法。利用光学测量显微镜景深小这一特点,将CCD沿金属表面垂直方向等间距拍摄部分聚焦的序列图像,然后采用方差聚焦测度算子确定融合图像中每点所属的高度层次,利用高斯插值方法计算微观物体表面更准确的高度信息,重构了三维微观形貌。同时探讨了三维表面粗糙度参数表征的可行性,通过与二维表面粗糙度参数的对比实验,验证了其正确性和可靠性。该方法对表面粗糙度的在线检测和更完整地表征3D形貌等方面具有参考价值。     

High-throughput measurement of rice tillers using a conveyor equipped with x-ray computed tomography

Tillering is one of the most important agronomic traits because the number of shoots per plant determines panicle number, a key component of grain yield. The conventional method of counting tillers is still manual. Under the condition of mass measurement, the accuracy and efficiency could be gradually degraded along with fatigue of experienced staff. Thus, manual measurement, including counting and recording, is not only time consuming but also lack objectivity. To automate this process, we developed a high-throughput facility, dubbed high-throughput system for measuring automatically rice tillers (H-SMART), for measuring rice tillers based on a conventional x-ray computed tomography (CT) system and industrial conveyor. Each pot-grown rice plant was delivered into the CT system for scanning via the conveyor equipment. A filtered back-projection algorithm was used to reconstruct the transverse section image of the rice culms. The number of tillers was then automatically extracted by image segmentation. To evaluate the accuracy of this system, three batches of rice at different growth stages (tillering, heading, or filling) were tested, yielding absolute mean absolute errors of 0.22, 0.36, and 0.36, respectively. Subsequently, the complete machine was used under industry conditions to estimate its efficiency, which was 4320 pots per continuous 24 h workday. Thus, the H-SMART could determine the number of tillers of pot-grown rice plants, providing three advantages over the manual tillering method: absence of human disturbance, automation, and high throughput. This facility expands the application of agricultural photonics in plant phenomics.     

Hard x-ray correlation analysis as a diagnostic tool for the measurement of magnetic turbulence in tokamaks

A diagnostic has been developed for the measurement and characterization of the magnetic turbulence occurring in the core region of a tokamak. A specially shielded detector looking in the tangential direction has been employed to measure the thin target bremsstrahlung from the core plasma. The thick target bremsstrahlung from the limiter is also recorded at the same time. Auto- and cross-correlation analyses have been shown to yield, respectively, the stochasticity of the magnetic fluctuations in the core region and the consequent diffusion coefficient of the nonthermal electrons. The measured stochasticity bears a relationship with the diffusion coefficient. Data obtained from internal magnetic probes corroborate the above trend but the hard x-ray measurement data are shown to be more reliable than those obtained from magnetic probes.     

一种利用相序测定原理的编码器计数方法

介绍了一种已获取发明专利的相序测定计数方法,以Atmel89S52单片机为基础,通过编码器的输出脉冲A和其反向脉冲A-产生中断,在中断服务程序中读取脉冲A、A-及与A脉冲相位差为90°的脉冲B的电平并与已在E2PROM中储存的状态字进行比较,由此来确定旋转方向并对脉冲进行加减计数。同时,该文也介绍了相应的硬件电路和软件程序。该方法在实际应用中的测试表明,当编码器频繁改变旋转方向时仍具有很高的测量准确度并能有效地抑制脉冲干扰信号。     

A photodiode amplifier system for pulse-by-pulse intensity measurement of an x-ray free electron laser

We have developed a single-shot intensity-measurement system using a silicon positive-intrinsic-negative (PIN) photodiode for x-ray pulses from an x-ray free electron laser. A wide dynamic range (10(3)-10(11) photons/pulse) and long distance signal transmission (>100 m) were required for this measurement system. For this purpose, we developed charge-sensitive and shaping amplifiers, which can process charge pulses with a wide dynamic range and variable durations (ns-μs) and charge levels (pC-μC). Output signals from the amplifiers were transmitted to a data acquisition system through a long cable in the form of a differential signal. The x-ray pulse intensities were calculated from the peak values of the signals by a waveform fitting procedure. This system can measure 10(3)-10(9) photons/pulse of ~10 keV x-rays by direct irradiation of a silicon PIN photodiode, and from 10(7)-10(11) photons/pulse by detecting the x-rays scattered by a diamond film using the silicon PIN photodiode. This system gives a relative accuracy of ~10(-3) with a proper gain setting of the amplifiers for each measurement. Using this system, we succeeded in detecting weak light at the developmental phase of the light source, as well as intense light during lasing of the x-ray free electron laser.     

A dual-channel, focusing x-ray spectrograph with uniform dispersion for Z pinch plasmas measurement

A dual-channel, focusing x-ray spectrograph with uniform dispersion (i.e., the linear dispersion of this spectrograph is a constant) is described for measuring the x-ray spectra emission from the hot, dense Al Z pinch plasmas. The spectrograph uses double uniform-dispersed crystals (e.g., a Quartz 1010 crystal and a Mica 002 crystal) as dispersion elements and a double-film box as detector to achieve the simultaneous recording of the time integrated spectrum covering a wide spectral range of ~5-9 A?. Since this spectrograph disperse the x-rays on the detector plane with uniform spacing for every wavelength, it needs not the calibration of the wavelength with spatial coordinate, thereby own the advantages of easiness and veracity for spectra identification. The design of this spectrograph and the example of experiment on the "Yang" accelerator are presented.     

Monochromatic x-ray radiography for areal-density measurement of inertial fusion energy fuel in fast ignition experiment

Ultrafast, two-dimensional x-ray imaging is an important diagnostics for the inertial fusion energy research, especially in investigating implosion dynamics at the final stage of the fuel compression. Although x-ray radiography was applied to observing the implosion dynamics, intense x-rays emitted from the high temperature and dense fuel core itself are often superimposed on the radiograph. This problem can be solved by coupling the x-ray radiography with monochromatic x-ray imaging technique. In the experiment, 2.8 or 5.2 keV backlight x-rays emitted from laser-irradiated polyvinyl chloride or vanadium foils were selectively imaged by spherically bent quartz crystals with discriminating the out-of-band emission from the fuel core. This x-ray radiography system achieved 24?μm and 100 ps of spatial and temporal resolutions, respectively.     

Scheduling hybrid flowshops with sequence dependent setup times to minimize makespan and maximum tardiness

This article addresses the problem of scheduling hybrid flowshops where the setup times are sequence dependent to minimize makespan and maximum tardiness. To solve such an NP-hard problem, we introduce a novel simulated annealing (SA) with a new concept, called “Migration mechanism”, and a new operator, called “Giant leap”, to bolster the competitive performance of SA through striking a compromise between the lengths of neighborhood search structures. We hybridize the SA (HSA) with a simple local search to further equip our algorithm with a new strong tool to promote the quality of final solution of our proposed SA. We employ the Taguchi method as an optimization technique to extensively tune different parameters and operators of our algorithm. Taguchi orthogonal array analysis is specifically used to pick the best parameters for the optimum design process with the least number of experiments. We established a benchmark to draw an analogy between the performance of SA with other algorithms. Two basically different objective functions, minimization of makespan and maximum tardiness, are taken into consideration to evaluate the robustness and effectiveness of the proposed HSA. Furthermore, we explore the effects of the increase in the number of jobs on the performance of our algorithm to make sure it is effective in terms of both the acceptability of the solution quality and robustness. The excellence and strength of our HSA are concluded from all the results acquired in various circumstances.