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With the development of nanotechnology, the preparation method of surface-enhanced Raman scattering (SERS) substrate has made significant progress, which promotes the application of SERS in food safety, environmental protection, and medical testing. We reported on the fabrication of silver-coated magnetic Fe3O4@phenolic resin (Fe3O4@RF) core–shell particles by a facile solvothermal method, followed by deposition of high-density Ag nanoparticles onto the phenolic resin surfaces through an in-situ reduction process. Analysis of Raman spectroscopy was performed by laser Raman spectrometer. The as-synthesized Ag-coated Fe3O4@RF particles as sensitive SERS substrates showed outstanding SERS performances toward probe molecules of 4-aminothiophenolas with a detection limit of 1 × 10–9 mol L–1. Moreover, the enhancement factor of the substrate was calculated to be about 2.86 × 105. Importantly, profiting from the excellent magnetism, the signal attenuated slightly only after three cycles measurements of SERS based on such composite substrates, indicating that Fe3O4@RF@Ag magnetic composite microspheres possessed the outstanding repeatability. On the basis of these results, it is believed that such Fe3O4@RF@Ag substrates are promising for the reusable detection of toxic molecules in practical applications.

Purpose For oil film thickness measurement using ultrasonic spring model, obtaining the isolated reflection from the oil film layer is the key point. While for oil film thickness measurement in thrust bearings with thin liner, the reflection from the substrate-Babbitt interface will overlap with the reflection from the oil film layer. This overlapping will render the ultrasonic spring model invalid. To obtain the isolated reflected signal from the oil film layer accurately, an adaptive method was developed to recover the overlapping echoes. Design/methodology/approach A genetic-algorithm-based support matching pursuit (GA-based SMP) was developed to provide the optimal echo number and initial parameters guesses automatically and efficiently. Then, the traditional expectation maximization (EM) model was used to fine tune the accurate results. Findings The developed method was tested using both simulated echoes and the overlapping echoes encountered in the ultrasonic oil film thickness measurement of thrust bearings. The results demonstrated that the developed method performed well on recovering overlapping echoes adaptively. Originality/value The work shows an adaptive method to recover the ultrasonic overlapping echoes. When used in ultrasonic oil film thickness measurement, it can help extend the application of traditional ultrasonic spring model to objects with four or more layers.

Objective To evaluate and compare the long-term efficacy and safety of microvascular decompression (MVD) and glossopharyngeal nerve roots rhizotomy (GNR) in the treatment of glossopharyngeal neuralgia (GN). Patients and methods The data of 37 patients with glossopharyngeal neuralgia undergoing MVD alone and MVD + GNR from July 2004 to March 2017 were analyzed retrospectively. Among them, 22 were MVD alone and 15 were MVD + GNR. All patients underwent preoperative cocaine experiments to verify diagnoses, preoperative magnetic resonance imaging examinations to detect compressing vessels near the root entry zone of the glossopharyngeal nerve. Operation via retrosigmoid approach, keyhole craniotomy, and postoperative efficacy was followed up. Results Efficacy: In the 22 patients with MVD alone, 19 patients were cured and 3 patients improved. In the 15 patients with MVD + GNR, 14 patients were cured and 1 patient improved. There was no significant difference between the 2 groups (χ test, P > 0.05). Complications Postoperative complications in MVD group: 2 patients had short-term hoarseness and drinking cough, 1 patient with cerebrospinal fluid leakage, 1 patient with intracranial infection, 1 patient with ipsilateral hearing loss, and no deaths; postoperative complications in MVD + GNR group: permanent hoarseness in 2 patients, short-term drinking cough and hoarseness in 4 patients, ipsilateral facial paralysis in 1 patient, 1 patient with cerebrospinal fluid leakage, no intracranial infection and death. The incidence of postoperative hoarseness and drinking cough in MVD + GNR group was higher than that in MVD group (χ test, P Conclusion The MVD alone was a safe and effective method for the treatment of primary glossopharyngeal neuralgia, the efficacy was equivalent to MVD + GNR, and had low incidence of hoarseness and drinking cough.

Objective The aim of the study was to evaluate the efficacy of microvascular decompression (MVD) and stereotactic gamma knife surgery (GKS) in the treatment of trigeminal neuralgia (TN) in the elderly. Patients and methods Retrospective analysis of 137 elderly cases with TN underwent MVD, partial sensory rhizotomy (PR) treatment from August 2007 to March 2017 and 56 cases underwent GKS treatment from May 2014 to February 2017 was made, compared the efficacy of MVD and GKS in different age groups. Results In 125 patients of MVD alone, the responsible vessels included 60 cases of superior cerebellar artery, 55 cases of anterior inferior cerebellar artery, 4 cases of venous vascular compression, 13 cases of mixed arteriovenous compression and 3 cases of vertebral artery, and 2 cases of no responsible vessel. Operation methods: MVD 125 cases, MVD + PR 10 cases, PR 1 cases, simple exploration in 1 case. Results of MVD surgery: Among 125 patients of MVD alone, 95 cases were cured, 15 cases improved, and 15 cases were ineffective. Among 10 cases of MVD + PR, cured in 9 cases and improved in 1 case. PR and simple exploration in 2 cases got pain disappeared. Postoperative complications of MVD: No deaths, CSF leakage in 2 cases, intracranial infection in 3 cases, ipsilateral hearing loss in 1 case, and ipsilateral facial paralysis in 1 case, delayed intracranial hematoma in 2 cases. After GKS treatment, the shortest onset time was from 9 days up to 6 months, an average of 2.2 months. Among 56 patients, 30 cases were cured, accounting for 53.6%, 20 cases improved, accounting for 35.7%, 6 cases were ineffective, accounting for 10.7%. Postoperative complications were facial numbness and dysesthesia, 7 cases, the incidence was 12.5%. In the group of 60 to 70 years old and the group of 70 to 80 years old, the treatment effect of MVD was better than that of GKS (χ test, P 80 years old group (χ test, P > 0.05). There was no significant difference in the therapeutic effect of TN underwent GKS among all age groups (χ test, P > 0.05). Conclusion Microvascular decompression should be performed more prudently in elderly patients (>80 years old), and the indications for PR should be relatively relaxed. MVD + PR could improve the curative effect in patients with trigeminal neuralgia >80 years. Gamma knife treatment of trigeminal neuralgia had high safety, less complications, and positive curative effect, especially suitable for patients >80 years.

Ultrasonic method is promising in oil film thickness measurement, while the commonly used commercial transducers are bulky and then sometimes hinder the application of this technology in field. Using the piezoelectric element is an alternative method and has the advantage of being convenient to be fixed. In this work, the key points of the use of the piezoelectric element are summarized. A calibration rig is set up to test the performance of oil film thickness measurement using piezoelectric element. The results show that using the piezoelectric element can measure the oil film thickness effectively and accurately.

Measurements of lubricant film pressure were made on water-lubricated rubber journal bearings with eight axial grooves. For measuring full circumferential pressure of bearing, pressure transducers were mounted on the shaft of test rig. Pressure data were transferred by means of wireless data transmission while shaft rotating. Pressures under different axial positions of bearing were simultaneously measured by different transducers on shaft. Film pressures of bearing operated under different loads, shaft speeds and water supply pressures were compared and analyzed. Experimental results reveal the existence of negative pressure region in water-lubricated rubber bearing. The maximum negative pressure appears at the beginning of the divergent region of fluid film. Different operating conditions are indicated by the fluctuation range of film pressure. For every operating condition, the biggest pressure fluctuation occurs at the axial middle part of bearing. The changes of load and shaft speed have larger influence to film pressure amplitude than the change of water supply pressure within experimental range.

Current bond quality evaluation technologies mainly depend on offline methods such as visual inspection of the appearance of bonds and batch destructive testing after bonding. In this paper we propose a new method for online evaluation of bonding quality. The method directly exploits the input electrical signal of piezoelectric transducer in ultrasonic wire bonder to evaluate the bonding quality. We present a feature extraction method in which the signal envelope is firstly obtained and then the envelope is separated into three sections, namely signal raise, smooth and attenuation, to characterize the transient property of the bonding process. The back-propagation artificial neural network (ANN) is used to establish the nonlinear relationships between the features and the bonding conditions. The experimental result shows that the proposed method can accurately identify four bonding conditions including wire missing, good bond, peeled off bond and non-stick bond.

Considering on the insufficiency of DV-HOP algorithm which doesn't use any range information in the localization of wireless sensor networks, we proposed a localization algorithm based on discrete imprecision range measurement. We first estimated the ranges between nodes using the different level of output powers. Second, the algorithm replaced the hop number in DV-HOP algorithm with the estimated range, and replaced the sum of hop with the sum of range measurement. Finally, we proposed a new algorithm to get comparatively precise localization. It has been shown that the localization error of the proposed algorithm in the paper is smaller than that of DV-HOP algorithm whenever in regular or irregular areas.

Fukushima nuclear power plant accident caused huge losses and pollution and it showed that the reactor coolant pump is very important in a nuclear power plant. Therefore, to keep the safety and reliability, the condition of the coolant pump needs to be online condition monitored and fault analyzed. In this paper, condition monitoring and analysis based on support vector machine (SVM) is proposed. This method is just to aim at the small sample studies such as reactor coolant pump. Both experiment data and field data are analyzed. In order to eliminate the noise and useless frequency, these data are disposed through a multi-band FIR filter. After that, a fault feature selection method based on principal component analysis is proposed. The related variable quantity is changed into unrelated variable quantity, and the dimension is descended. Then the SVM method is used to separate different fault characteristics. Firstly, this method is used as a two-kind classifier to separate each two different running conditions. Then the SVM is used as a multiple classifier to separate all of the different condition types. The SVM could separate these conditions successfully. After that, software based on SVM was designed for reactor coolant pump condition analysis. This software is installed on the reactor plant control system of Qinshan nuclear power plant in China. It could monitor the online data and find the pump mechanical fault automatically.