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This paper is a comprehensive experimental report on the neutron radiation effects of distributed optical fiber sensors with enhanced Rayleigh scattering profiles in an in-pile environment. Femtosecond laser direct writing was used to inscribe Type-II modifications in standard telecom fibers and radiation-hardened fibers with fluorine-doped cores. Rayleigh backscattering signals were enhanced for continuous 1.5 m. In-pile lead-out sensors tests were carried out at the MIT Research Reactor for two months, which was operated at a nominal power of 5.7 MW with fast neutron (>0.1 MeV) flux of 1.29 × 1014 n/cm2/s and an in-core temperature of up to 560 °C. Using the Optical Frequency Domain Reflectometry technique, the backscattering profiles of fiber sensors were interrogated with a 3-cm spatial resolution to monitor the temperature profile of the reactor. Results show that laser inscribed Type-II modifications in the form of nanogratings are highly stable against extreme temperature and ionizing radiation. Both standard telecom fibers and radiation-hardened fibers with laser-enhanced Rayleigh profiles can continuously perform distributed temperature measurements over the entire duration of the in-pile testing. Temperature coefficients of sensors and spectral shift quality were studied as functions of total radiation fluence. To the best of our knowledge, we present for the first time, the temperature profile of an operating nuclear reactor core with 3-cm spatial resolution, enabled by distributed fiber sensors with laser-enhanced Rayleigh scattering profiles. The high spatial resolution measurements can provide valuable data for the design and validation of digital twin and virtual reality of nuclear energy systems.

The purpose of this work was to validate the efficacy and safety of free medial plantar flap in repair of hand wounds resulted from high-voltage electrical burn. 22 patients with high-voltage electrical burn wounds were retrieved between July 2016 and July 2018 in the Affiliated Zhengzhou Central Hospital of Zhengzhou University. All the wounds were the entrance of high-voltage electrical current. After thorough debridement, the blood vessels, nerves, tendons, joints were exposed to defects with different degrees. The soft tissue defects were repaired with the free medial plantar flap repair in 12 patients and medium-thickness skin graft in 10 patients. Postoperative management was similar between the two groups. All the operations were completed within 6 h. In the free medial plantar flap group, the mean follow-up period was (11.3 ± 2.4) months, ranging from 9 to 15 months, and all flaps survived; there were no vessel crises. Flaps of 10 patients healed without any complications, and local necrosis occurred in two cases, with healing after debridement. The two-point discrimination (TPD) was 7.0–11.0 mm, and the mean DASH score was 45.6 ± 7.4. In the medium-thickness skin graft group, the mean follow-up period was (10.9 ± 1.8) months. All flaps survived, and local contracture occurred in 3 cases. The TPD was 8.0–11.0 mm, and the mean DASH score was 60.7 ± 9.3. The free medial plantar flap is an ideal option for repairing the hand soft defects resulted from the high-voltage electrical burn.

This paper presents a method of reel-to-reel femtosecond laser direct writing that enables the continuous inscription of low-loss and high-temperature stable Rayleigh scattering centers inside the core of single-mode optical fibers for distributed temperature sensing up to 1000°C. By examining the correlation between the Rayleigh backscattering profile and the cross-section morphology of femtosecond laser-induced nanograting in fiber cores, this paper reveals the mechanisms that underlie the fabrication of high-temperature stable distributed fiber sensors with low loss. By fine-tuning laser exposure conditions, the femtosecond laser-fabricated Rayleigh scattering enhanced section could achieve an optimized propagation loss of 0.01 dB/cm with an increased signal-to-noise ratio of over 35 dB for meters of lengths. Long-term high-temperature stability of the Rayleigh scattering enhanced section was successfully demonstrated, with improved thermal stability and signal-to-noise ratio. The fabrication method presented here provides a promising technique to improve the performance of Optical Frequency-Domain Reflectometry based distributed sensing for harsh environment applications.

This paper presents a fast demodulation algorithm to determine fiber Bragg grating (FBG) from spectra acquired by low wavelength resolution spectrometers. A modified and improved Buneman frequency estimation algorithm is employed in tracking FBG wavelength and eliminating FBG wavelength discontinuities in real-time wavelength demodulation calculations. The FBG demodulation algorithm was tested using a 512-element detector array spectrometer with a 156 pm/element resolution. At a 2-kHz spectrum acquisition rate, the demodulation algorithm achieved a 0.048 pm Bragg wavelength resolution. The computational efficiency and robustness of the new algorithm was compared with a Gaussian FBG peak fitting method. Our method provides a real-time demodulation scheme to track FBG wavelength using low-resolution spectrometers or tunable lasers. It has the potential to significantly reduce the cost of FBG interrogation systems that are employed in high-sensitivity and high-speed sensing applications.

This paper reports the development of fiber optical hydrogen sensors using palladium and gold alloy nanostructures as sensor materials for hydrogen measurements using a D-shaped fiber as a platform. Using a maskless reactive ion etching technique, silica nanocone structures were formed on the surface of the D-shaped fiber. Palladium and gold alloys were deposited on the surface of nanostructured D-shaped fiber to form a nano-alloy sensor film. Evanescent interaction between guided light propagated in the fiber core and nano-alloy enabled highly sensitive hydrogen detection from concentrations that ranged from 0.25% to 10% in atmosphere pressure. The formation of nanostructured alloy enabled by the nanocone surface led to more than 3 times faster in sensor response time and significant improvements in sensor sensitivity and reversibility. The work presented here demonstrates that highly controllable VLSI microfabrication schemes can be applied to produce nanostructured sensor films on optical fibers for high-sensitivity chemical sensing.

Plasmonic nanoantennas have been widely explored for boosting up light-matter interactions due to their ability of providing strongly confined and highly enhanced electric near fields, so called ‘hot-spots’. Here, we propose a dielectric-loading approach for hot-spots engineering by coating the conventional plasmonic nanoantennas with a conformal high refractive index dielectric film and forming dielectric-loaded plasmonic nanoantennas. Compared to the conventional plasmonic nanoantennas, the corresponding dielectric-loaded ones that resonate at the same frequency are able to provide an extra enhancement in the local electric fields and meanwhile spatially transfer the hot spots to the dielectric surfaces. These findings have important implications for the design of optical nanoantennas with general applications in surface enhanced linear and nonlinear spectroscopies. As a demonstration application, we show that the maximum achievable fluorescence intensity in the dielectric-loaded plasmonic nanoantennas could be significantly larger than that in the conventional plasmonic nanoantennas.

A cascaded hydrogen sensors based on intrinsic Fabry-Perot interferometer (IFPI) fabricated by femtosecond laser in single mode fibers is presented for monitoring the hydrogen gas at the room temperature. A detection limit of hydrogen of 0.25 % is achieved.

An integrated approach is presented to detect pipeline defects using distributed acoustic sensors and machine learning. Over 80% accuracy for defected pipe identification was achieved with defect depth classifications with error less than 1-mm.

Femtosecond laser direct writing was used to continuously induce Rayleigh scattering centers in meters of single-mode optical fiber using a customized roll-to-roll setup, which can be used to improve the performance of scattering-based distributed sensing.

We report on the experimental investigation of polarity-switchable hot electron-induced photocurrents in dual-plasmonic nanostructures, consisting of two layers of gold nanoparticles (AuNPs) separated by a TiO2 film. Hot electrons generated through the non-radiative decay of the localized surface plasmon resonances supported by the top and bottom layers of AuNPs can be simultaneously injected into the TiO2 film in opposite directions and counteract each other. As a result, the polarity and magnitude of the net photocurrents can be tailored by controlling the population of hot electrons either generated from or collected by the two layers of AuNPs. We believe the wavelength-dependent photocurrent polarity switching could be useful for biosensors with a direct electrical readout and photoconversion applications.

This Letter presents an approach to produce multiplexable optical fiber chemical sensor using an intrinsic Fabry–Perot interferometer (IFPI) array via the femtosecond laser direct writing technique. Using the hydrogen-sensitive palladium (Pd) alloy as a functional sensory material, Pd alloy coated IFPI devices can reproducibly and reversibly measure hydrogen concentrations with a detection limit of 0.25% at room temperature. Seven IFPI sensors were fabricated in one fiber and performed simultaneous temperature and hydrogen measurements at seven different locations. This Letter demonstrates a simple yet effective approach to fabricate multiplexable fiber optical chemical sensors for use in harsh environments.

We propose a fabrication technique to multiplex Intrinsic Fabry-Perot Cavity sensors using femtosecond laser induced Rayleigh scattering centers. Up to 20 sensors were multiplexed and demodulated using a fast white-light interferometry demodulation algorithm.

A machine learning-based model was trained on beam propagation simulation data of a femtosecond laser direct written 1-D waveguide array structure with varying refractive indices, to predict the refractive index difference of laser-induced waveguide.

To separate the azeotrope of 2,2,3,3-tetrafluoro-1-propanol (TFP) and water, the energy-saving heterogeneous azeotropic dividing-wall column (DWC) is proposed using chloroform as an azeotropic agent. Compared with the conventional design, the total condenser duty reduction of 44.57%, total reboiler duty reduction of 42.66% and TAC reduction of 37.79% by the DWC design are obtained. Based on the simulation results, the energy-saving in the DWC design is due to the thermal coupling of the conventional design and the separation of water by the decanter with the purity of 99.5 mol%, rather not to the removal of remixing effect for the column sequence. The control strategy performance for the conventional and DWC designs are satisfactory, since TFP and water are separated with high purity, despite the disturbances of the flow rate of fresh feed, fresh feed composition and liquid split ratio.

In this paper, a novel bonding anchorage system characterized by the diverged arrangement of CFRP bars inside socket with resin-based adhesive was proposed for CFRP cable. The anchorage system was experimentally tested to verify its performance and numerical simulations were conducted to investigate the influential factors in proposed anchorage to cable bearing capacity and failure mode. In the anchorage system, the bonding capacity with the selected high-efficient adhesives and the bonding length in socket determined by the simulated bonding behaviors was verified experimentally. Besides, the effect of the adhesive stiffness on the uniformity of the tensile stress distribution of CFRP bars in cable, as well as the effects of the adhesive wedge action on the cable fracture mode were investigated with the finite element simulation . The experimental tests and numerical simulations reveal the influences of resin-based adhesive and adhesive wedge action on anchorage performance.

The paper studies the size effect on the tensile strength of parallel carbon fiber reinforced polymer (CFRP) wire stay cable in the macroscale. First, an asymptotic weakest-link Weibull model that incorporates a statistical length effect for the tensile strength of longitudinal composites is proposed in this research. For the proposed model, the weakest-link effect gradually becomes dominant and causes a decrease in strength that increases along the length of the longitudinal elements. The asymptotic threshold length L ρ on the strength analysis can be evaluated by the asymptotic weakest-link Weibull model. The strength data of single carbon fibers and impregnated bundles with different lengths obtained by previous studies are employed to validate the proposed model and the log-likelihood ratio test and the Bayesian information criterion (BIC) are used as the criteria for the validation of the proposed model. The tensile strengths of CFRP wires with different lengths are obtained and analyzed by using the proposed model, and the results obtained from the random strength field model proposed by Vořechovský and Chudoba are illustrated and discussed in detail. Finally, the actual strengths of two parallel CFRP wire cables are compared with the simulated results to illustrate the Daniels’ effect on the strengths of parallel CFRP wire cables. To evaluate the strengths of parallel CFRP wire stay cables, the length effect and Daniels’ effect should be considered in the design of the CFRP cables to ensure safety and reliability.

So far, the relation between financial agglomeration and export trade is complex and there are few related studies. However, research on this topic will be of great value to the development of the Guangdong-Hong Kong-Macau Greater Bay Area (the Greater Bay Area). This paper aims to use the mediation model to analyze the role of technological innovation as an mediator variable between financial agglomeration and export trade. Based on the relevant data of the Greater Bay Area from 2009 to 2018, regression analysis was performed using the three equations of the mediation model. The mediator variable was then replaced to conduct a robustness test, and it was found that there is indeed an mediation effect; technological innovation acts as an mediator variable between financial agglomeration and export trade. Therefore, it can be concluded that the financial agglomeration in the Greater Bay Area can effectively promote technological innovation, while technological innovation will inhibit exports to a certain extent.

A cascaded string of six intrinsic Fabry-Perot Interferometer sensors was fabricated inside a silica fiber for high-temperature sensing using ultrafast laser direct writing. These sensors were interrogated by the fast white-light interferometer demodulation in real-time, yielding a temperature sensitivity between 4.4–13.4nm/°C for up to 800°C at a spatial resolution of 1-cm.

Objective: To explore the clinical value of 256-slice spiral CT coronary angiography combined with serum uric acid (UA) and apolipoprotein B/A I (ApoB/A I) ratio in detecting vulnerable coronary plaques (VP) in middle-aged and elderly diabetic patients. Methods: 1. Patients hospitalized in the Department of Cardiology, Second Affiliated Hospital of Xuzhou Medical University from January 2016 to January 2018 with diabetes mellitus and coronary CTA diagnosed as coronary heart disease were divided into three groups according to the nature of plaque: 28 vulnerable plaque group, 30 mixed plaque group and 25 calcified plaque group. 26 patients with simple DM and without coronary plaque group were included as control group and other patients in DM group. Three groups were compared.2. Record the general data of the subjects. All the subjects were treated with UA, ApoA I, ApoB, FIB, FPG and TG after admission. Results: There were significant differences in UA and ApoB/AI ratios among groups (P < 0.05). Logistic regression analysis showed that FIB, ApoB, UA and ApoB/AI were independent risk factors for vulnerable plaques (P < 0.05). Conclusion: The ratio of UA to A poB/A I is an independent risk factor for vulnerable plaque in middle-aged and elderly patients with coronary heart disease and DM. The ratio of coronary CTA combined with UA and A poB/A I has important clinical value in predicting the vulnerability of plaque in middle-aged and elderly patients with coronary heart disease and DM.

UWFBG was fabricated in single-mode fiber through Ti-Doped Silica Outer Cladding using KrF 248-nm excimer laser for phase-sensitive distributed acoustic sensing (DAS). This paper suggests a new approach to produce sensing fibers for DAS.

The femtosecond laser has emerged as a powerful tool for micro- and nanoscale device fabrication. Through nonlinear ionization processes, nanometer-sized material modifications can be inscribed in transparent materials for device fabrication. This paper describes femtosecond precision inscription of nanograting in silica fiber cores to form both distributed and point fiber sensors for sensing applications in extreme environmental conditions. Through the use of scanning electron microscope imaging and laser processing optimization, high-temperature stable, Type II femtosecond laser modifications were continuously inscribed, point by point, with only an insertion loss at 1 dB m−1 or 0.001 dB per point sensor device. High-temperature performance of fiber sensors was tested at 1000 °C, which showed a temperature fluctuation of ±5.5 °C over 5 days. The low laser-induced insertion loss in optical fibers enabled the fabrication of a 1.4 m, radiation-resilient distributed fiber sensor. The in-pile testing of the distributed fiber sensor further showed that fiber sensors can execute stable and distributed temperature measurements in extreme radiation environments. Overall, this paper demonstrates that femtosecond-laser-fabricated fiber sensors are suitable measurement devices for applications in extreme environments.

As striking lightning impulse waveforms in power transformers are quite different from the standard lightning impulse waveform (SLIW) used in the withstand voltage tests, it is essential to identify the breakdown characteristics of oil-impregnated paper (OIP) under non-SLIW and to quantitatively compare them with those under SLIW. On that basis, the impulse insulation levels of power transformers can be rationally determined and then the insulation specifications can be evaluated to maintain high equipment reliability. In this paper, with damped alternating oscillation waveform as a representative basis, the breakdown characteristics of oil-impregnated paper were experimentally obtained by changing the frequency and damping rate of the applied voltage. All experiments were conducted using a column-column electrode model. In addition to the 50% breakdown voltages (U50), Minimum breakdown voltage Umin and V-t characteristics under different circumstances, the influence of various parameters on breakdown characteristics and the possible reasons were discussed. After comparing waveforms and corresponding results, the specific relationship between waveform parameters and U50 were expressed as a single equation. As a result, the breakdown voltage was 1.106 to 1.435 times higher than that under SLIW depending on frequency and damping rate. The steepness of the wave peak and the duration of high voltage around wave crests are considered to be two important factors affecting the breakdown voltage. An effective way was proposed to predict U50 of oil-impregnated paper as a reference for insulation specifications irrespective of wave shape. These results support the rationalization of insulation for actual lightning impulse waveforms in the power transformers.

During the decades-long operation, oil paper insulation in power transformers may suffer the effect of thousands of lightning impulses. Such interesting but rarely studied phenomenon, also known as accumulative effect, may cause irreversible damage to the oil paper insulation, or even premature failure. Therefore, in this work, the influence of repeated lightning impulses on the oil paper insulation, especially the mechanism behind this phenomenon, was experimentally investigated. We determined the accumulative breakdown characteristics of the oil paper insulation and observed the influence of the repeated lightning impulses on the dissolved gas in oil and the degree of polymerization. Specifically, the space charge distribution in the oil paper samples and the relationship between the interval time and accumulative breakdown characteristics were experimentally determined in the end. The test results indicate that the accumulative effect only exists in the cellulose paper rather than the transformer oil. Such effect was considered to be the consequence of electrical degradation and accumulation of space charge.

At present, the insulation performances of electrical apparatus under lightning impulse voltages are always evaluated by the withstand test of standard lightning impulse voltage (1.2/50 µs), which is recommended by IEC Standard. However, the actual time parameters of transformer invading lightning impulse voltage present an obvious dispersibility characteristics. The standard wave shape is only representative of one particular class of lightning waves, which is far from satisfactory to act as the guidance waveform in the design of power equipment insulation. On the basis of the above research background, the relationship between breakdown characteristics of oil paper insulation and time parameters of applied lightning impulse voltage was investigated in this study. The 50% breakdown voltage characteristics of oil paper insulation under lightning impulse voltage with different time parameters were determined. The test results indicate that a short wave front time could lead to relatively low 50% breakdown voltage, while when the wave tail time varied, the 50% breakdown voltage of oil paper insulation barely changed. At last the simulation model of oil paper insulation was developed, and the current flowing through the oil paper insulating system under lightning impulse voltage was calculated. On the basis of the simulating results, the relationship between current and time parameters was analysed.

According to the IEC Standard, the insulation performances of power apparatus under lightning impulse voltages are evaluated by the withstand test of standard lightning impulse voltage, with the wave front/tail time of 1.2/50 μs. However, the standard lightning impulse voltage originally obtained from the transmission lines or triggering lightning towers, is quite different from the invading lightning impulse voltage in the power transformers. Hence, in this work, an attempt has been made to obtain the waveform characteristics of invading lightning impulses in power transformers using an overvoltage online monitoring system. Energy Method was then proposed to convert the recorded oscillatory waveform into double-exponential waveform defined by IEC Standard. And the statistical waveform parameters of recorded invading lightning impulses, namely, the non-standard lightning impulses, were determined based on the Energy Method. Current insulation assessment methods, for example, the V-t characteristics, are far from satisfactory to meet the demand of insulation design for the power apparatus, whereas the impulse breakdown voltage-number of voltage applications characteristics (V-N characteristics) could well evaluate the long term performance of insulation system. Therefore, we experimentally identified the V-N characteristics of oil paper insulation under impulse voltage with different waveforms, including non-standard lightning impulse voltage, and then mathematically analyzed the obtained data. At last, the influence of wave front/tail time on the V-N characteristics of oil paper insulation was experimentally studied. The test results indicate that the insulation performances of oil paper insulation under repeated nonstandard lightning impulse voltages and under standard switching impulse voltages were better than that under repeated standard lightning impulse voltages. And the capacity to withstand repeated voltage became increasingly stronger with the increase in wave front time or the decrease in wave tail time. The breakdown voltage, however, was only related to the wave front time of applied impulse voltage.

This paper presents a method of using femtosecond laser inscribed nanograting as low-loss– and high-temperature–stable in-fiber reflectors. By introducing a pair of nanograting inside the core of a single-mode optical fiber, an intrinsic Fabry-Perot interferometer can be created for high-temperature sensing applications. The morphology of the nanograting inscribed in fiber cores was engineered by tuning the fabrication conditions to achieve a high fringe visibility of 0.49 and low insertion loss of 0.002 dB per sensor. Using a white light interferometry demodulation algorithm, we demonstrate the temperature sensitivity, cross-talk, and spatial multiplexability of sensor arrays. Both the sensor performance and stability were studied from room temperature to 1000°C with cyclic heating and cooling. Our results demonstrate a femtosecond direct laser writing technique capable of producing highly multiplexable in-fiber intrinsic Fabry-Perot interferometer sensor devices with high fringe contrast, high sensitivity, and low-loss for application in harsh environmental conditions.

Repeated impulses have long been considered to affect the insulation properties of electrical equipment. This interesting but rarely studied phenomenon may pose great risks to the reliable operation of power equipment. Therefore, in this work, we focus on the accumulative effect of repeated lightning impulses on the oil-impregnated paper (OIP) used in power transformers. Specifically, we study the effect of space charge on the accumulative characteristics of OIP. A repetitive impulse accumulating test platform was set up, and the tests were conducted to obtain the accumulative characteristics of OIP under repeated lightning impulses. The accumulative characteristics of OIP with various interval time were experimentally identified to study the influence of interval time on the accumulative effect. Then, space charge in OIP samples were investigated using the pulsed electro-acoustic technique. Charge behavior in OIP was analyzed under different conditions, i.e., changing the applied times, amplitude and interval time of the applied lightning impulses. Charge injection and transport occurred during lightning impulse accumulation. The increased application of lightning impulses, high applied voltage, and short interval time contributed to the accumulation and transport of space charges. At last, the possible mechanisms of the accumulative effect are discussed in this article based on the experimental results.

Water-environment monitoring network (WMN) is a wireless sensor network based real-time system, which collects, transmits, analyzes and processes water-environment parameters in large area. Both cluster selection mechanisms and energy saving strategies play an important role on designing network routing protocols for the WMN. Since those existing routing algorithms can not be used directly in the WMN, we thus propose an improved version of LEACH, a LEACH-Head Expected Frequency Appraisal (LEACH-HEFA) algorithm, for the WMN in this paper. Simulation results show that the LEACH-HEFA can balance the energy consumption of nodes, rationalize the clustering process and prolong the network lifetime significantly in the WMN. It indicates that the LEACH-HEFA is suitable to the WMN.

Water-regime monitoring system is a wireless-sensor-network (WSN) based real-time system. It often collects, transmits, analyzes and processes water regime parameters in large areas. Since the cluster-head selection mechanism affects directly on the energy consumption and network lifetime, both the cluster selection mechanism and the energy saving strategy play an important role on the design of network routing protocols. Current routing algorithms usually have two shortages: unbalanced energy loads and short network lifetime. They often could not be used directly in water regime monitoring systems. In this paper, based on the idea of cluster-head expected frequency appraisal, a LEACH-HEFA (LEACH-Head Expected Frequency Appraisal) algorithm was proposed for improving the performances. Simulation results clearly show that LEACH-HEFA algorithm can balance the energy consumption of nodes in the WSN, rationalize the clustering process and prolong the network lifetime effectively. It indicates that this proposed algorithm is suitable to water regime monitoring systems.

中医学の耳圧療法によって肥満治療を希望する患者に使用した。特別な食事治療や運動療法などを用いなくて, 本療法を受けた28名の女性肥満症では1ヵ月の治療後で1.0～4.8kg, 3ヵ月連続治療で3.0～9.6kg, 4ヵ月連続治療で15.0kg以上の体重減少がみられた。その総有効率は98.0%である。Broca 桂法により求めた肥満度は耳圧療法前と比較して全員平均14.8%を減少した。血中脂質異常に伴う肥満症の患者は本治療によって体重減少すると同時に, 血中の高コレステロール, 高中性脂肪 (高TG) は有意に下降した。以上の成績に関して, 耳圧療法では肥満症に対する一定の臨床効果があることと, その効果のメカニズムの一部としては体内の脂質代謝に及ぼす影響があろうと考えられる。