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Rolling bearings are important moving parts of the transmission system in a helicopter. Rolling bearings are prone to failure due to poor working conditions, and the fault diagnosis of these parts is difficult. For rolling bearings, periodic impulses indicate that faults exist in the components. These impulsive features at the early stage are weak and immersed in heavy noise. The features can be distinguished through wavelet de-noising. However, existing wavelet threshold de-noising methods may not extract the feature available due to the limitation in adjacent scale information, and conventional term-by-term thresholding ignores the effect of neighboring coefficients. A new approach for wavelet threshold de-noising is presented in this paper. First, a wavelet transform domain cross-correlation filter is constructed following the theories of wavelet correlation analysis. Then, a novel method for de-noising is proposed, which uses not only the Haar wavelet cross-correlation as the basic estimation to match the impulse but also the neighboring coefficient shrinkage strategy to further enhance the impulsive features and suppress residual noise. Analysis results show that the proposed approach outperforms the soft- and hard-thresholding methods in terms of the combined criterion. It also compares favorably to the other wavelet method for signals with low kurtosis or low signal-to-noise ratio. Bearing fault prognosis results verify the effectiveness of the proposed approach in extracting impulsive features from noisy signals.

The negative-capacitance field-effect transistor(NC-FET) has attracted tremendous research efforts. However, the lack of a clear physical picture and design rule for this device has led to numerous invalid fabrications. In this work, we address this issue based on an unexpectedly concise and insightful analytical formulation of the minimum hysteresis-free subthreshold swing (SS), together with several important conclusions. Firstly, well-designed MOSFETs that have low trap density, low doping in the channel, and excellent electrostatic integrity, receive very limited benefit from NC in terms of achieving subthermionic SS. Secondly, quantum-capacitance is the limiting factor for NC-FETs to achieve hysteresis-free subthermionic SS, and FETs that can operate in the quantum-capacitance limit are desired platforms for NC-FET construction. Finally, a practical role of NC in FETs is to save the subthreshold and overdrive voltage losses. Our analysis and findings are intended to steer the NC-FET research in the right direction., Negative Capacitance field-effect-transistor has long been touted as a steep-slope logic switch. Here, the authors present a lucid formulation that reveals the intrinsic limitation of NC-FETs in achieving steep-slope switching characteristics and highlights their more practical role in saving the voltage losses in modern FETs.

In order to improve the penetration and strike capability of unmanned aerial vehicles (UAVs), a cooperative guidance law is presented for multiple UAVs attacks on the same maneuvering target. Firstly, based on the finite-time consistency convergence theory, a multiple UAVs time cooperative guidance law is designed, the guidance law is not bound by the end time, which enhances the anti-interference ability during the guidance period. Secondly, based on the sliding mode variable structure control theory, the guidance law of multiple UAVs attack angle constraint is designed; the guidance law is optimized according to the quasi- sliding mode control, which weakens the chattering of the sliding mode. Finally, the simulation verifies the effectiveness of the designed guidance law.

Determining non-metallic inclusions (NMIs) are essential to engineer ultra-high-strength steel as they play decisive role on performance and critical to probe via conventional techniques. Herein, advanced Synchrotron X-ray absorption coupled with photoemission electron microscopy and first-principles calculations are employed to provide the structure, local bonding structure and electronic properties of several NMI model systems and their interaction mechanism within and the steel matrix. B K-, N K-, Ca L2,3- and Ti L2,3-edge spectra show that the additional B prefers to result in h-BN exhibiting strong interaction with Ca2+. Such Ca2+-based phases also stabilize through TiN, revealing the irregular coordination of Ca2+. Observed intriguing no interaction between TiN and BN is further supported with the first-principles calculations, wherein unfavorable combination of TiN and h-BN and stabilization of bigger sized Ca2+-based inclusions have been found. These observations can help to optimize the interaction mechanism among various inclusions as well as steel matrix.

Understanding molecular behavior of water on titanium dioxide nanotubes (TiNTs) is of great interest in order to enable potential application of TiNTs in dye-sensitized solar cells, photocatalysis, and biomedical coatings. Using molecular dynamics simulations, we study the static and dynamic properties of water on TiNT with a diameter of ∼1.0 nm. The TiNT modified by a carbon nanotube (CNT) inside is built to investigate the effect of surface chemistry changes on the sorption and diffusion of water. The results show that the water molecules outside TiNT conform with the two-layer model for water on a planar surface. The difference is that the first water layer is further from Ti5c as an effect of surface curvature, indicating the easier water desorption on the surface. This layer disappears for water inside TiNT, leaving a water layer with the hydrogen atoms pointing to the O2c to form hydrogen bonds. The simulations also reveal that the orderly structure is destroyed in the carbon modified nanotubes. Dif...

Evidence indicates that curcumin seems to improve outcomes in non-alcoholic fatty liver disease (NAFLD). A meta-analysis was performed to evaluate the effects of curcumin inNAFLD. We searched PubMed, EMBASE, and the Cochrane Library from inception through March 2018 to identify randomized controlled trials (RCTs) evaluating the role of curcumin inNAFLD. The mean difference (MD) and 95% confidence interval (CI) were calculated. Four RCTs with a total of 229 NAFLD patients were included. Curcumin was more likely to lower LDL-C, triglycerides, FBS, HOMA-IR, weight and AST levels compared with placebo, and the difference was statistically significant [MD = − 27.02, 95% CI (− 52.30, − 1.74); MD = − 33.20, 95% CI (− 42.30, − 24.09); MD = − 5.63, 95% CI (− 10.36, − 0.90); MD = − 0.53, 95% CI (− 1.00, − 0.05); MD = − 2.27, 95% CI (− 3.11, − 1.44); MD = − 7.43, 95% CI (− 11.31, − 3.54), respectively]. However, the beneficial effect of curcumin did not achieve statistical significance in lowering total cholesterol, HDL-C, HbA1c, ALT or insulin levels [MD = − 30.47,95% CI (− 60.89. − 0.06); MD = − 0.98, 95% CI (− 2.88, 0.92); MD = − 0.41, 95% CI (− 1.41, 0.59); MD = − 6.02, 95% CI (− 15.61, 3.57); MD = − 0.92, 95% CI (− 2.33, 0.49)]. Curcumin is effective in lowering LDL-C, triglycerides, FBS, HOMA-IR, weight, and AST levels in NAFLD patients, and it is well tolerated. Further RCTs are required to confirm our findings.

It is discussed that a new method for active power measurement under the conditions of distortion signals. Accurate measurement of the power consumed by the distorted signals has been focused on in recent years due to its practical utilities. In this work, a mathematical description of powers is deducted in the conditions of distorted signals according to a simplified model of the electrical network. Then, a rational measuring method of the electric energy for distorted signals is proposed on the basis of the analysis of the power flow. Also, a measuring method based on multiple wavelets was employed for measuring the active power in the conditions of unsteady distorted signals. Experimental results demonstrate that, by using the simulated typical distorted signals, the proposed measurement method can produce extremely accurate results compared to theoretical results.

To observe the clinical efficacy and the change of airway responsiveness to Chinese medicine (CM) in treating cough variant asthma (CVA).Ninety-four patients who had confirmed the diagnosis of CVA were selected and randomly assigned to the treatment group and the control group by the blocked randomization method. The ratio of the two groups was 2:1. The treatment group had 63 patients that were treated by CM, lost in 10 cases, 53 patients had finished the trial. The control group had 31 patients that were treated by montelukast tablets and theophylline, lost in 5 cases, 26 patients had finished the trial, two weeks as one therapeutic course. The syndrome efficacy, cough efficacy, symptom score and the airway responsiveness between two groups were observed.The comparison of the syndrome efficacy: the total effective rate of the treatment group was 90.57% and the control group was 76.92%, and the two groups were significantly different (P0.05). The comparison of the cough efficacy: the total effective rate of the treatment group was 98.11% and the control group was 80.77%, and the two groups were also significantly different (P0.05). Syndrome scoring and cough scoring were all significantly lowered, but the airway responsiveness was not significantly lowered.The treatment of CM could ease the cough, improve the syndrome, and shows obvious advantages compared with the control group, which is worthy of extensive clinical application.

The development process and method of using VBA technology to develop two-dimensional gallery system of components of injection moulds for plastics taking ejector pin for example is described in detail, which includes establishing parameters database of components, design and calling of user interface, program and menu. The two-dimensional gallery system of components of injection moulds for plastics developed in AutoCAD can generate two-dimensional drawing automatically with the design parameters that user selects and it is convenient for user to plot.

Based on the thorough study of electrolysis enrichment, gas–liquid phase catalytic exchange, gas chromatography for hydrogen isotope separation, and hydrogen–oxygen recombination technologies, a CECE–GC prototype system with disposal capability of 10 ton/a of tritiated water was set up in the middle of 2004 at China Academy of Engineering Physics (CAEP). It has successfully fulfilled the demonstration experiment of recovering deuterium from deuterium contained water and simulation operation of recovering tritium from tritiated water. Total concentration factor of CECE about 4, and the separation factor of tritium around 10 for operation time of 240 h with this system. The GC system of 50 m3/d has successfully recovered 90% hydrogen from 10 m3 tritiated hydrogen gas in 6 h and the tritium concentration in this part was depleted more than 1000 times. This experimental system served as an important step stone for further engineering works.

The spatial characteristics of Thomson scattering in a linearly polarized laser field are investigated. The results show that the electron's motion and spatial distributions of Thomson scattering depend sensitively on the phase η0 at which the electron is injected to the laser field. When η0 equals to 0 or π, the electron motion is a zigzag motion and the spatial distributions of the emission show fourfold or twofold symmetry. In other cases of phases, there is a steady drift motion of electron in the transverse direction, which results in the absence of the zigzag motion and a breakdown of the symmetry of the spatial distributions as well.

In order to improve the efficiency of the metrology department and promote the development of intelligent weighing apparatus, this paper proposes the design of the weighing monitoring system from two aspects of measurement system and monitoring system. In the measuring end, STC89C52 microcontroller is used as the main control chip to achieve the accurate measurement of pressure. The temperature drift of the pressure sensor is reduced by using the pressure sensor temperature compensation algorithm based on the combination of Lagrange difference and least square. The monitoring system uses the upper computer, the Wi-Fi module and the Android mobile phone to remotely monitor the measurement system intuitively, receives and displays the measurement data in real time, and can invoke the historical data. The system realizes the real-time monitoring of the weighing instrument and makes the weighing instrument become the integrated remote monitoring equipment, which has many functions such as data analysis, remote diagnosis and remote operation. This design is of great significance to study the intelligent weighing field.

Due to large-scale wind farms connected to the grid, the grid computing needs to consider the impact of wind farm when integrated into the power grid. Firstly, the single turbine model is analyzed; the positive and negative sequence impedance of a single turbine in the large and small operating modes are got by analyzing whether Crowbar resistance is accessed and the number of wind turbines put in actual operation. Then, according to the wiring way of wind farm and the influence of transformer accessed, wind turbine and transformer will be equivalent to wind Chassis variant Group. Finally, according to the actual parameter calculation of wind farm we get the equivalent impedance, and use the results verify the correctness of fault calculation.

The influence of micro-structure on magnetic properties of amorphous powder core was investigated. The results show that the amorphous powders of the powder core become crystallized with the increase of annealing temperature, and the permeability decreases from 60 to 12, the core loss increases from 0.2 to 0.3 W °Cm−3, DC-bias characteristic was improved with further increase of annealing temperature, and the magnetic properties become deteriorated due to decrease of permeability and enhancement of coercive force resulting from the crystallization of amorphous powder.

The aim of this study was to investigate the effect of different ocular massage health education methods on ocular massage in glaucoma patients after trabeculectomy. Eighty-six patients with glaucoma after trabeculectomy (86 eyes) were randomly divided into two health education groups. One group was a watch video group (43 patients, 43 eyes), while the other was an orally taught health education group (43 patients, 43 eyes). Patients were followed up for 1 week, 1 month, and 3, 6, and 12 months after discharge. Records of the patient responses after health education, compliance of patients with follow-up, and intraocular pressure were determined. Measurements included intraocular pressure and differences between the watch video and orally taught health education groups. The differences between the watch video group and orally taught health education group were not statistically significant at 1 week and 1 month, while the differences were statistically significant at 3, 6, and 12 months. The results indicated that health education videos can enable glaucoma patients to have a better mastery of ocular massage after trabeculectomy. According to the needs of patients, health education video use produced good results and should be promoted.

Details of an electro-optic, hybrid current-sensing instrument, and its application to high-voltage power line current measurement, are presented. The current is first detected via a Rogowski coil, followed by conversion of the detected current into a frequency-modulated optical pulse signal in the high-voltage area. Subsequently, the optical pulse signal is transmitted to the ground through an optical fiber cable. Finally, the measured current is recovered from the optical pulse signal by a ground-located signal-processing module. Compared with conventional current transformers, widely used for high-voltage line current measurement, this instrument provides a significant reduction in size, weight, and cost, together with features of convenient installation, secure operation, and high accuracy. Furthermore, it can be configured to be compatible with conventional secondary meters widely used in today's power plants and substations. In 1996, a prototype of this instrument was demonstrated online at a power substation and has shown good accuracy, stability, and safety for more than two years.

Based on a circular arc scanning model and the formularizing of hysteresis curves of piezoelectric tubes, a three‐dimensional scanning model of piezoelectric tubes is presented and used to compensate distortions of measured images scanned by a piezoelectric tube. This model‐based compensation method can correct three‐dimensional distortions simultaneously with two key parameters which are obtained just by measuring vertical deformation‐voltage characteristics of the piezoelectric tube. Experiments showing the effectiveness of this method are also discussed in this article.

Diagnostic measurement of single picosecond event in high energy density physics, laser fusion, plasma radiation, and combustion, is of great importance. However, the measuring of the shape of the single X-ray pulse and the synchronization of X-ray and the laser pulse in picosecond resolution is still a great challenge. Restricted by the transit time of electrons, the time-resolution limit of a conventional framing camera based on the microchannel plate is 40 ps. Centered on the full-optical modulation effect of the light-probe, a novel method for X-ray detection of picoseconds temporal resolution based on low temperature GaAs is proposed in this work. The basic physical mechanism of the detector can be explained in both macroscopical and microcosmic ways. In the macroscopical way, the X-ray radiation absorption in the sensor material produces a transient, non-equilibrium electron-hole pair distribution that results in a transient differential change of the local refractive index, which is then sensed by the reflectivity changes of the optical probe beam. In the microcosmic way, X-ray absorption creates photoelectrons and the core level holes are subsequently filled through Auger or fluorescence processes. These excitations ultimately increase conduction and valence band carriers that perturb optical reflectivity.#br#To verify the proposed X-ray detection method, a Fabry-Perot detector is designed, which consists of a 5 μm thick GaAs layer surrounded by a GaAs/AlAs distributed Bragg reflector. The test is carried out on a femtosecond laser facility, where the X-ray source is produced by focusing the 56 fs Ti: Sapphire facility laser, with a central wavelength of 800 nm, onto an aluminum foil. Then the X-ray pulse induces a transient optical reflectivity change in GaAs, which is a powerful tool for establishing the high-speed X-ray detection.#br#The experimental results indicate that this technology can be used to provide X-ray detectors with a temporal resolution of tens of picoseconds. By optimizing the material, the temporal resolution can be enhanced to be less than 1 ps. Through further development, this X-ray detector could provide an insight into previously unmeasurable phenomena in many fields. Future work will focus on developing much faster devices characterizing both the rise and fall time and imaging array technology.

In this paper, a method of the aperture-integration and surface-integration and adaptive grid (AI-SI-AG) for ultra-wideband airborne radome analysis is present. The theoretical results by (AI-SI-AG) and measured data are given with good agreement. It is found that by this method the pattern of omni-directional-antenna and directional-antenna enclosed in radome can be computed efficiently and accurately. It has shown significant practical value in engineering applications.

Based on a circular arc scanning model of piezoelectric tubes, the influence of the tip length mounted on a tube upon the transverse scanning and the relation between the vertical and the transverse displacement of the tip are reported. With this simple model one can obtain three‐ dimensional features of a piezoelectric tube scanner by just measuring the vertical deformation and a few geometric sizes of the tube without knowing the detailed parameters of the tube. The estimated scanning by the model may be 15% larger than the actually measured one for a certain piezoelectric tube because of the edge effects of the tube. However, the model can be simply revised on the basis of experiments.

In this paper, a hybrid method is present based on equivalent surface aperture integration(ESAI) and geometry optics(GO). In this algorithm, the reflected field along the inner surface of radome is approximately regarded as equivalent currents, which radiate through the wall and constitute the total field together with the transferred field. The integration over the out surface generates exact far field. The theoretical simulation agrees with the measurement quite well.

In the physics optics algorithm of wide-band radome analysis, the arbitrary radome are usually expressed by grid model. Since the radome works in ultra-wide frequency band, it is unsuitable to use fixed size grid in calculation of surface-field-integration. Especially in high frequency it is impossible for workstation to generate ultra-fine grid with UG software. In this paper, an adaptive grid technique is present. Based on the grid generated at low frequency, the size of the grid can be varied with frequency adaptively to realize the uniform convergence of the surface integration. This technique minimizes the compution time without loss of accuracy.

The radiation of a secondary surveillance radar (SSR) antenna with a radome is composed of transmission radiation and reflection radiation. The vector superposition between the transmission and reflection radiation is a complicated problem. In this paper, by using the hybrid method of aperture-integration and surface-integration technique with the ray tracing technique, the radiation of an SSR linear array with an ellipsoid radome is analyzed. The calculated result is compared with the experiment and good agreement. is obtained.

A hybrid method of aperture-integration and surface-integration techniques combined with the ray-tracing technique is presented. By this method, the effect of the radome on point source pattern are analyzed. The solution to the vector superposition of the transmission lobe and reflection lobe for the point source pattern with the radome is given. The theoretical results agree with the measurement quite well.

In this paper, a new numerical method for analyzing a general EM problem is presented and its application to analysis of wire antennas is given. In the analysis, the matrix equation resulting from a method-of-moments analysis to an EM problem is converted to another matrix equation with the matrix order being greatly reduced. To guarantee a sufficient solution accuracy, the generalized Jacobian iteration is proposed. Although the method is introduced based upon wire antenna analysis, the formulation is applicable to other kinds of EM problems equally well.

A quasi-TEM technique is presented for analyzing the microstrip taper baluns. The generalized cascade parameters and other performance indices of the baluns are calculated and compared with the published or measured ones.

It is considered that the radiation field of an end-fed elliptical array whose main beam points toward the array normal and whose elements are equally-spaced in the ellipse is the output of a time-invariant system. On the basis of the linear system, the transfer function of this system is obtained and the formula is presented. The time required for the establishment of a steady pattern is considered. >

Ohmic contacts with Ti/Al/Ti/Au source and drain electrodes on AlGaN/GaN high electron mobility transistors (HEMTs) were fabricated and subjected to rapid thermal annealing (RTA) in flowing N2. The wafer was divided into 5 parts and three of them were annealed for 30 s at 700, 750, and 800 °C, respectively, the others were annealed at 750 °C for 25 and 40 s. Due to the RTA, a change from Schottky contact to Ohmic contact has been obtained between the electrode layer and the AlGaN/GaN heterojunction layer. We have achieved a low specific contact resistance of 7.41 × 10−6 Ωcm2 and contact resistance of 0.54 Ωmm measured by transmission line mode (TLM), and good surface morphology and edge acuity are also desirable by annealing at 750 °C for 30 s. The experiments also indicate that the performance of ohmic contact is first improved, then it reaches a peak, finally degrading with annealing temperature or annealing time rising.

In this paper, the AlGaN/GaN HEMT (high electron mobility transistors) with different ohmic contact structures are fabricated, and the effect of different ohmic contact pattern on GaN HEMT electrical properties is studied. A conventional ohmic contact electrode structure and a new ohmic contact structure with a contact hole are fabricated and subjected to rapid thermal annealing (RTA) in flowing N2. After different structured AlGaN/GaN HEMTs are annealed at 750 ℃ for 30 seconds, in HEMTs with a conventional structure ohmic contact still does not form while in the device with ohmic contact holes a good ohmic contact is already formed. Then the surface morphology of different multilayer electrode structures is measured. Comparing Ti/Al/Ti/Au with Ti/Al/Ni/Au, we can conclude that the structure Ti/Al/Ni/Au has a more smooth surface after annealing. After testing the HEMT devices with different structures, higher transconductance and saturation current are found for the devices with ohmic contact holes. But a serious current collapse phenomenon has been observed when the gate voltage is set between 0.5 V and 2 V.

A diagram representation method is proposed to interpret the complicated charge pumping (CP) processes. The fast and slow traps in CP measurement are defined. Some phenomena such as CP pulse rise/fall time dependence, frequency dependence, the voltage dependence for the fast and slow traps, and the geometric CP component are clearly illustrated at a glance by the diagram representation. For the slow trap CP measurement, there is a transition stage and a steady stage due to the asymmetry of the electron and hole capture, and the CP current is determined by the lower capturing electron or hole component. The method is used to discuss the legitimacy of the newly developed modified charge pumping method.

The spatial distribution of Thomson scattering in an ultrashort laser pulse is investigated. It is found that the spatial distribution of the radiation depends sensitively on the carrier-envelope (CE) phase η0 of the ultrashort driving laser pulse. At η0=0,π, the spatial distribution of the radiation shows fourfold or twofold symmetry, while the symmetry breaks down at other CE phases. The collimation of the radiation also depends sensitively on the CE phase, and it reaches the best at η0＝±π/2. These results suggest that it is possible to control the spatial distribution of Thomson scattering by varying the CE phase of the driving laser pulse, or the CE phase of the ultrashort laser pulse can be measured by utilizing the phase-dependent spatial symmetry of Thomson scattering.

High harmonics generation (HHG) from Ne atom driven by a multi-cycle 43 fs laser pulse is investigated. The numerical simulation demonstrates that when the intensity of the driving laser is over-saturated, the atom will be ionized rapidly during a few optical cycles, this will lead to a continuous multi-plateau structure in the cutoff region of the high harmonics spectrum from the neutral atom. It is also shown that the signal of high-order harmonics from the ion becomes remarkable when the driving laser is super intense. The superposition of an appropriate sub-plateau can give single attosecond soft X-ray pulse, and the effect of HHG from ion has been eliminated through the band selection.

The nonlinear Thomson scattering by an electron in a focused circularly polarized laser beam is investigated and a novel scheme for single attosecond pulse generation is proposed.Through computer simulation we find that by using a tightly focused laser beam,the ratio of the highest peak pulse and the second highest peak pulse of the radiation which is defined as the signal-to-noise ratio can be efficiently increased, such that a single attosencond pulse rather than a train of attosecond pulses is obtained. The pulse duration of the radiation decreases and the signal-to-noise ratio increases with increasing laser intensity.Simultaneously,the signal-to-noise ratio can be also improved as the beam-waist decreases.We find that a single attosencond pulse can be generated by using a few-cycle ultrashort laser pulse as well.

In this work, the authors present their recent progress in the development of a platform for the mid-infrared wavelength range, based on suspended silicon waveguides with subwavelength metamaterial cladding. The platform has some intrinsic advantages, which make it a very promising candidate for sensing applications in the molecular fingerprint region. Specifically, it can cover the full transparency window of silicon (up to a wavelength of 8 μm), only requires one lithographic etch-step and can be designed for strong light-matter interaction. Design rules, practical aspects of the fabrication process and experimental results of a complete set of elemental building blocks operating at two very different wavelengths, 3.8 and 7.7 μm, are discussed. Propagation losses as low as 0.82 dB/cm at λ0 = 3.8 μm and 3.1 dB/cm at λ0 = 7.7 μm are attained for the interconnecting waveguides.