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Wall fluctuating pressure in the boundary layer is critical for physical understanding of the surface flow and detection resolution optimization of the underwater vehicle (UV). In this study, a flexible microelectromechanical system (MEMS) vanadium-doped zinc oxide (VZO) film piezoelectric pressure sensor array is developed for underwater applications; 2% VZO film achieves figure of merit of -54.5, far higher than the previous records of the contemporary thin films, indicating excellent receiving sensitivity. The sensors are designed and fabricated using a four-mask VZO-on-SOI process. An array of $2\times 5$ sensors is flexibly integrated on a polyimide foil and insulated by a parylene C waterproof cover. Calibrations in a plane wave tube are demonstrated. About 0.64- $\pm ~0.06$ -mV/Pa pressure sensitivity at the frequency of 10 Hz–2 kHz and the maximum nonlinearity of 0.3% from 0 to 50 Pa are achieved. The capabilities of the flexible sensors array in a real-time sensing situation on an UV model are validated. The laminar, transition, and turbulent flow at different positions of the vehicle model are detected successfully from the sensor outputs. The result shows that the amplitude and power energy of the fluctuation pressure at the transition case are higher than that of the laminar and turbulent flow. The presented sensors array with merits of low power, miniature size, and low foot print offers a flexible and readily surface-mountable system, exhibiting promising potentials in underwater applications.

In this letter, a novel spoof surface plasmon polaritons (SSPPs) bandpass filtering unit (BP-FU) is proposed. The equivalent circuit model of BP-FU is given and by establishing its ABCD-matrix, the pass band and forbidden band are analysed theoretically, which behaves the feature of bandpass. Meanwhile, the simulated dispersion curve of BP-FU shows bandpass feature. Subsequently, the proposed BP-FU is applied to design a bandpass filtering transmission line (TL). The TL obtains the bandpass filtering feature spontaneously due to the periodically arranged BP-FUs. The TL consisting of BP-FUs can be excited by the methods like exciting traditional unit and a transverse magnetic wave propagates along the TL. The field characteristic is as same as classical SSPPs TL. The measured results of the prototype of the TL shows a passband from 6.66 GHz to 10.06 GHz and ultrawide stopbands ( $\vert S_{21}\vert \lt $ -22 dB) from nearly 0 GHz to 5.36 GHz and 10.89 GHz to 40 GHz. The measured results indicate good application prospect in single conductor multifunction circuit.

Gradually increasing interest in the exploration of marine resources and the rapid proliferation of underwater vehicles requires the issue of electromagnetic (EM) detection of underwater complex targets (UCTs) to be solved urgently. In this communication, a hybrid method combining the finite-difference time-domain (FDTD) method and the Sommerfeld integral (SI) method is proposed to simulate the low-frequency (LF) scattering field from UCTs. In the proposed method, integral expressions and approximate expressions of the SI are used to calculate the fields in the near and far ranges, respectively. Meanwhile, the inaccuracies caused by the LF breakdown are mitigated based on the results obtained in the stable region and the trends exhibited by correct results. Subsequently, the scattering fields from the UCTs at different locations generated by an underwater two-element antenna array are simulated and analyzed. The results show that the scattering magnetic field (SMF) distributions of the targets at different locations are similar, while the field values differ significantly. The existence of targets can be ascertained from the SMF components, and the directions of UCTs with respect to the antenna can be obtained roughly by comparing their SMF components Hy.

A domain decomposition method is presented for analyzing electromagnetic problems involving multiple nonoverlapping scatterers or electrically large scatterers. We first construct a sparse or simple-to-invert impedance matrix that does not account for partial mutual coupling. Then, approximate the solution to the original problem using the relationship between the actual impedance matrix and the matrix presented above. The proposed method is based on the principle of inverting the impedance matrix by blocks, which reduces the complexity compared with an inversion of the whole impedance matrix. This method features rapid convergence and high precision, making it suitable for large electrically scattering objects. Several examples demonstrate the accuracy and efficiency of the proposed method.

Microstrip antenna has attracted extensive attention in the field of seafloor detection and underwater radar due to its stable structure and strong beam directivity. In this letter, the total-field scattered-field source finite-difference time-domain method with a simplified calculation method is considered to analyze the electromagnetic wave propagation generated by an underwater microstrip antenna (UMA). We analyze the field distributions of UMA, reduced-scale antenna and the two-element array composed of two UMAs. Meanwhile, the effect of element spacing on the radiation field distribution generated by the array is specifically studied. In addition, the scattering field of a metallic ellipsoidal target is analyzed. The simulations show that seawater can be used as the medium layer of the UMA in order to generate energy distribution in a near region similar to that of the conventional microstrip antenna. Furthermore, the element spacing for the underwater array should be adjusted based on the practical application.

In this letter, a multibeam leaky-wave antenna (LWA) based on a modified Luneburg lens (LL) beamforming network is proposed. The antenna performs a simple structure and low profile with 2-D beam scanning. First, the modified LL serves as a beamforming network since its variation range ratio of refractive index can be determined by the relative permittivity of the substrate. This can be simply achieved using a printed circuit board technique rather than the square root of two of conventional LL. Then, the relationship between the input port angle and the multibeam angle is analyzed using the geometric-optical method. Finally, a high-scanning-rate LWA array based on spoof surface plasmon polaritons is designed, and its open-stopband is effectively suppressed. A prototype is simulated and fabricated. The measured results show that the proposed antenna has a multibeam range of −42° to 40° in the E-plane and a beam scanning range of −53° to 44° in the H-plane within 8–10.5 GHz, which agrees well with the calculation and simulation.

Abstract: The approximately analytical bound and scattering state solutions of the arbitrary l-wave Klein-Gordon equation for the mixed Manning-Rosen potentials are carried out by an improved new approximation to the centrifugal term. The normalized analytical radial wave functions of the l-wave Klein-Gordon equation with the mixed Manning-Rosen potentials are presented and the corresponding energy equations for bound states and phase shifts for scattering states are derived. It is shown that the energy levels of the continuum states, reduce to the bound states of those at the poles of the scattering amplitude. Some useful figures are plotted to show the improved accuracy of our results and the special case for wave is studied briefly.

In this letter, a dual circularly polarized periodic leaky-wave antenna based on spoof surface plasmon polaritons (SSPPs) with linearly sweeping beams is proposed. The antenna can simultaneously radiate left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) beams. Single-arm Archimedean spirals serve as radiators and are designed. Based on linearity analysis and curve fitting, SSPPs structure with potentially linear scanning ability are selected. Finally, the axial ratio (AR) and S-parameter for the proposed SSPPs antenna with spiral radiators are optimized around the broadside frequency using longitudinally asymmetric analysis. A prototype is fabricated and measured results show that the proposed antenna achieves a relative 3 dB AR bandwidth of 31.6% (8–11 GHz) with the same LHCP and RHCP scanning range of 65° and linearly sweeping ability.

A shooting and bouncing ray (SBR) method for electrically large targets containing anisotropic material is presented in this communication. In contrast to the traditional SBR method, ray tracing is carried out inside the anisotropic material. First, the electromagnetic propagation matrix of an anisotropic material with arbitrary optical axis orientation is studied. The propagation of the ray tube inside the anisotropic material is then analyzed, and the path is recorded using quadtree. This method can be applied to targets containing nonuniform thickness anisotropic material, whether dielectric or magnetic. Numerical results show that the proposed method is highly efficient and accurate.

In this brief, cross-shaped resonators (CSRs) are integrated in spoof surface plasmon polaritons (SSPPs) unit, and a novel compact single-conductor SSPPs transmission line (TL) with bandpass feature is proposed. In this design, a unit structure based on classical SSPPs structure embedded with a CSR is proposed. To analyze the proposed unit structure, scattering parameters and ABCD-matrix theories are used. After the theoretical analysis, a SSPPs TL with bandpass filtering property is designed. The simulated passband is from 7.9 to 12.2 GHz with a relative bandwidth of 42%. A prototype is fabricated and measured. The measured results are in agreement well with the simulated ones. This proposed structure is attractive and useful for the design of high integrated SSPPs circuits.

In this letter, a method of tunable gain microstrip antenna for compact pattern-reconfigurable array is proposed. The tunable gain element is realized by integrating a switchable resistive attenuator, which is composed of a RF SP4T and four loading resistors. The method is demonstrated on a six-element sidelobe reconfigurable array operating at 2.45 GHz, which consists of three kinds of tunable gain elements with different gains. The measurements have a good agreement with the simulations and show the first sidelobe level range from −14 to −20 dB of the array at 2.45 GHz in H-plane is achieved based on the tunable gain range from 5 to 1.9 dBi of the elements.

In this letter, a triple-beam leaky-wave antenna (LWA) based on modulated spoof surface plasmon polaritons transmission line (TL) with hybrid period is presented. The one side of SSPPs TL is modulated sinusoidally with period of P1, and another side is modulated with composite period of P2 and P3. The analysis of dispersion curves indicates that the modulated periods at each side of the TL is independent and hence the radiation beams can be controlled independently by adjusting the modulation periods. In this design, the LWA radiates three beams simultaneously. From 7.8 to 9.1 GHz, the gain difference of beams is lower than 3 dB, which have cover range from 49° to 149°. To validate the performance of the designed LWA, a prototype is fabricated and measured. The measured results are in good agreement with the simulated ones.

In this brief, a broadband $9\times9$ Butler Matrix (BM) and its extension for multibeam antenna array (MAA) application are presented. Based on the configuration of $3\times3$ beamforming network (BFN) comprised of three couplers and two 90° phase shifters, the topology of $9\times9$ BM is built, which can provide in-phase signals at output ports. And a broadband $9\times9$ BM is implemented to verify the design by adopting broadband components. The results indicate that the designed broadband $9\times9$ BM achieves equal power division and 9 uniformly distributed progressive phases (PPs) between output signals in a relative bandwidth of 40% when the 9 input ports are excited, respectively. And the fabricated $9\times9$ BM is applied in MAA for producing 9 beams including a boresight beam. In addition, according to the design method of $9\times9$ BM, the topology of the extended $27\times27$ BM is built and presented, which validates that an extended BM with higher order can be realized by the design method, and the extended BM can also provide in-phase signals at output ports.

In this article, a new approach to designing a modified $N^{2} \times N^{2}$ Butler matrix (BM) based on an $N$ -way directional coupler (NWDC) is presented. First, by introducing phase shifters and ingeniously arranging the input and output ports, the topologies of $9 \times 9$ BM based on a three-way directional coupler (3WDC) and $16 \times 16$ BM based on a four-way directional coupler (4WDC) are built. Next, according to the design method of $9 \times 9$ BM and $16 \times 16$ BM, the topology design of modified $N^{2} \times N^{2}$ BM based on NWDC is developed. Considering whether there are progressive phase differences (PPDs) of 0° at output ports, the two cases in which $N$ is odd and even are discussed. Finally, in order to verify the design method, a prototype of microstrip $9 \times 9$ BM working at 5.5 GHz is designed, fabricated, and measured. The results show that the designed microstrip $9 \times 9$ BM achieves equal power division and nine different PPDs among the output signals when the nine input ports are excited, respectively, which meets design expectations. And it is used as a beamforming network (BFN) for a multibeam antenna array (MAA) to generate nine radiation beams. And then, the design method of modified $N^{2} \times N^{2}$ BM is validated by the implementation of microstrip $9 \times 9$ BM. And the design method of the modified $N^{2} \times N^{2}$ BM provides a novel approach for BFN technology when massive input and output ports are required.

In this communication, we analyze the field distributions of underwater very-low-frequency (VLF) two-element array composed of two symmetrical antennas. This analysis is carried out with the improved parallel total-field scattered-field source (TSS) finite-difference time-domain (FDTD) method with sea–air boundary field value conversion and thin-wire algorithm. We specifically analyze the field distribution in the range close to the antenna array in seawater. Furthermore, we also study the field propagation law in air propagating across the air–sea interface.

The present study introduces a weak magnetic field sensor that utilizes a laminated cantilever structure, consisting of a magnetostrictive layer, a piezoelectric layer, and a substrate layer. Consequently, the transformation from the magnetic signal to the electrical signal is accomplished through the consistent mechanical stress in both layers. A comprehensive theoretical model has been developed to evaluate the impact of key structural parameters on the magnetoelectric (ME) sensing performance, enabling the optimization of the device design. By incorporating vanadium (V) as a dopant element, a Zn-V-O film with a piezoelectric coefficient as high as 35 pm/V is fulfilled. Furthermore, the high piezomagnetic properties of Galfenol make it a suitable candidate as a magnetostrictive layer. Sensor prototypes were fabricated for experimental verification through the utilization of MEMS technology. The film was characterized using techniques, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and piezoelectric force microscopy (PFM). The ME testing experiments indicated that the magnetostrictive coefficient could achieve about 9.32 kV/(cm $\cdot $ Oe) at resonant frequencies for sensors with varying lengths and a 20- $\mu \text{m}$ -thick Si substrate. The proposed sensor exhibits promising potential for improving weak magnetic field detection performance.

BackgroundIn advanced disease, breathlessness becomes severe, increasing health services use. Breathlessness triggered services demonstrate effectiveness in trials and meta-analyses but lack health economic assessment.MethodsOur economic study included a discrete choice experiment (DCE), followed by a cost-effectiveness analysis modelling. The DCE comprised face-to-face interviews with older patients with chronic breathlessness and their carers across nine UK centres. Conditional logistic regression analysis of DCE data determined the preferences (or not, indicated by negative β coefficients) for service attributes. Economic modelling estimated the costs and quality-adjusted life years (QALYs) over 5 years.FindingsThe DCE recruited 190 patients and 68 carers. Offering breathlessness services in person from general practitioner (GP) surgeries was not preferred (β=−0.30, 95% CI −0.40 to −0.21); hospital outpatient clinics (0.16, 0.06 to 0.25) or via home visits (0.15, 0.06 to 0.24) were preferred. Inperson services with comprehensive treatment review (0.15, 0.07 to 0.21) and holistic support (0.19, 0.07 to 0.31) were preferred to those without. Cost-effectiveness analysis found the most and the least preferred models of breathlessness services were cost-effective compared with usual care. The most preferred service had £5719 lower costs (95% CI −6043 to 5395), with 0.004 (95% CI −0.003 to 0.011) QALY benefits per patient. Uptake was higher when attributes were tailored to individual preferences (86% vs 40%).ConclusionBreathlessness services are cost-effective compared with usual care for health and social care, giving cost savings and better quality of life. Uptake of breathlessness services is higher when service attributes are individually tailored.

A new topology of modified Butler matrix (BM) based on three-way directional coupler (TWDC) is proposed in this brief. The two TWDCs are regarded as two submatrices, by alternately arranging the output ports of the two submatrices and introducing a front network consisting of 3dB/90° hybrid couplers, 3dB power divider and phase shifters, a topology of modified five-input six-output ( $5 \times 6$ ) BM is constructed. In order to verify the design method, a prototype of microstrip $5 \times 6$ BM operating at 5.5 GHz is implemented and it is used as a beamforming network (BFN) for multibeam antenna array (MAA) to generate five radiation beams including a boresight beam. The measured and simulated results coincide well with each other. And according to the design method, a topology of extended $9 \times 12$ BM is designed based on the $5 \times 6$ BMs, which validates the capacity of building a modified BM with a higher number of the input and output ports.

Pyrano[4,3-c]pyridine-diones, which are the key skeleton of bioactive compounds and functional materials, are usually prepared via a multistep synthesis using expensive substrates. This work demonstrates that Rh(III)-catalyzed dual C(sp2)–H functionalization and C–O/C–N annulation of monoamide fumarates can produce pyrano[4,3-c]pyridine-1,5(6H)-diones in high yield (up to 82%) in a single step. The substrates of monoamide fumarates and acetylenes are structurally simple, readily available, and inexpensive. The additive AgSbF6effectively raised the yields. On account of easier dehydrogenation of OH in the COOH group than NH in the amide group in the reaction, the process first undergoes C–O annulation and then is succeeded by C–N annulation.

ABSTRACT The autogenous volume deformations of concrete with MgO expansive materials and fly ash cured in different ages were measured, and the morphologies of it were observed through scanning electron [...]

Abstract In this paper, five functionals fixed point theorem is extended and applied to singular boundary value problem with p-Laplacian. The existence of at least three positive solutions is obtained. [...]

Abstract A new test method--delayed autoclave expansion test has been used in this study to evaluate the soundness of concrete that contains intrinsic dead-burnt MgO and adscititious lightly burnt MgO. [...]

Abstract In order to assure the outer concrete of Longtan dam in China possesses excellent of frost resistance, the losses of strength, mass and air void characteristics of roller compacted [...]

ABSTRACTThis study investigates the potential of e-commerce to enhance rural agricultural businesses by allowing farmers and producers of agricultural products to sell on platforms such as Taobao. Using a survey methodology, we analyze whether Internet sales enhance rural businesses in either of two ways – increasing producers’ profit margins by avoiding monopolistic or collusive local middlemen and reorganizing the supply chain in an efficient manner, and increasing sales volume by reaching a larger market. The study also investigates barriers that rural Internet sellers face. For the purpose of this study, we conducted field interviews with online shop owners and a nation-wide survey of rural agricultural online shops. The survey results confirm our hypothesis, and demonstrate that market forces – the increase of producers’ profit margins and the expansion of market, aided by government initiatives, have driven down barriers to rural e-commerce and created economic stimulus that benefits rural economic development and potentially eliminates poverty. The study also suggests that more can be done by the government in increasing e-commerce training, subsidizing shipping services in rural areas, and establishing local e-commerce associations. Recent research also conforms with our conclusions drawn from the survey results, beyond which, the evolution of platform economy has posed new challenges and further research is required.

To improve the lateral stability of the semi-trailer train at high speeds, the active steering control strategy for tractor and semi-trailer is proposed and examined using closed-loop dynamic simulation. A linear yaw plane model with 3-DOF of semi-trailer train is built and verified, and a directional preview driver model applied the preview-predictor follow strategy is developed and integrated with the vehicle model. The proportional feedforward, fuzzy feedback, and proportional-integral-derivative controller (PID) active steering controllers are proposed and adopted individually or in combination, the effectiveness of the active steering control strategy presented have been verified and analysed based on the driver/articulated vehicle closed-loop control system. The simulation results show that the active steering control strategy proposed has an obvious advantages over the conventional uncontrolled vehicle, effectively reducing the values of index, and improving the performance of high-speed lateral stability. The method has certain reference value for improving the active safety of articulated heavy vehicle.

C30H20O4N2Cl2S2, Orthorhombic, Pca21, a= 16.9808(14) Å, b= 7.5227(6) Å, c= 20.8027(16) Å, V= 2657.4(4) Å3, Z= 4, Rgt(F) = 0.0642, wRref(F2) = 0.1809, T= 293 K.

C15H16ClNO2, triclinic, P1‾$‾{1}$(no. 2), a= 7.4339(12) Å, b= 8.2564(14) Å, c= 12.184(2) Å, α= 108.804(6)∘, β= 93.672(5)∘, γ= 94.373(6)∘, V= 702.8(2) Å3, Z= 2, Rgt(F) = 0.0650, wRref(F2) = 0.1974, T= 273 K.

A facile solvothermal method was developed for synthesis of magnetic nickel-based iron oxide nanocomposites (MNFOs) with different ratios of Ni2+to Fe3+for different reaction time. Two factors including dosage of Ni source and length of reaction were investigated for influence on the morphology and composition of MNFOs, as well as their distinct selectivity for different phosphopeptides. After thorough characterization, the possible formation mechanism of MNFOs was proposed. Very interestingly, MNFOs with Ni2+/Fe3+ratios of 4:5 prepared for 8 h (MNFO-S) and for 24 h (MNFO-L) can selectively capture global- and monophosphopeptides at the fmol level with excellent enrichment performance. These two affinity probes have been exploited to isolate and enrich the phosphopeptides from human normal hepatic cells HL 7702 after exposure to atmospheric fine particulates (PM2.1), which revealed that the protein phosphorylation level was increased significantly in cells after stimulation by fine particulate matters. The findings could provide a new insight for the nickel-based affinity protocol to analyze the mutation of phosphopeptides during cellular signaling pathways in response to exogenous environment stimulation. Consequently, this present work proposed a promising strategy to isolate monophosphopeptides from global phosphopeptides for phosphoproteome research.

The determination of the total amount of water pollutant emission in different regions is a difficult problem faced by managers and researchers. Previous studies mostly focused on operability and fairness with little attention paid to local water quality. In order to make total emission pollutant control (TEPC) truly serve the improvement of water quality, a water total emission pollutant allocation model was built based on water environmental carrying capacity (WECC) in this paper. This model was used to construct a water pollutant emission control allocation scheme for 28 cities in Henan Province, China. The results showed that the chemical oxygen demand (COD) reduction rates for these cities ranged from 16.8 to 38.6% and ammonia-nitrogen (NH3-N) reduction rates ranged from 5.7 to 43.5% in 2020, which were different from the previous targets for these cities without considering their current status of water quality. The largest COD reduction rates for different types of point sources (industrial, urban, and large-scale livestock sources) were 35.4%, 39.0%, and 38.0%, respectively, and the largest NH3-N reduction rates were 62.2%, 42.5%, and 43.5%, respectively. This study solves the problem of long-term disconnection between TEPC and water quality improvement in China. The results can also be applied to implement the TEPC to improve water quality in other regions with a similar problem. [ABSTRACT FROM AUTHOR]

C16H8O4, monoclinic, Pc(no. 7), a= 3.7133(1) Å, b= 9.7214(4) (2) Å, c= 15.5765(6) Å, β= 96.121(2)°, V= 559.08(3) Å3, Z= 2, Rgt(F) = 0.0506, wRref(F2) = 0.1274, T= 150(2) K.

Our previous study has shown the cingulate cortex abnormalities in first-episode drug naïve (FEDN) schizophrenia patients with comorbid depressive symptoms. However, it remains largely unknown whether antipsychotics may induce morphometric change in cingulate cortex and its relationship with depressive symptoms. The purpose of this study was to further clarify the important role of cingulate cortex in the treatment on depressive symptoms in FEDN schizophrenia patients.

C23H13NO4, monoclinic, P21/n(no. 14), a= 11.6537(6) Å, b= 5.1315(2) Å, c= 26.8047(13) Å, β= 96.266(3)°, V= 1593.4(13) Å3, Z= 4, Rgt(F) = 0.0531, wRref(F2) = 0.1432, T= 90.0(5) K.

With the vigorous expansion of nonlinear adaptive filtering with real-valued kernel functions, its counterpart complex kernel adaptive filtering algorithms were also sequentially proposed to solve the complex-valued nonlinear problems arising in almost all real-world applications. This paper firstly presents two schemes of the complex Gaussian kernel-based adaptive filtering algorithms to illustrate their respective characteristics. Then the theoretical convergence behavior of the complex Gaussian kernel least mean square (LMS) algorithm is studied by using the fixed dictionary strategy. The simulation results demonstrate that the theoretical curves predicted by the derived analytical models consistently coincide with the Monte Carlo simulation results in both transient and steady-state stages for two introduced complex Gaussian kernel LMS algorithms using non-circular complex data. The analytical models are able to be regard as a theoretical tool evaluating ability and allow to compare with mean square error (MSE) performance among of complex kernel LMS (KLMS) methods according to the specified kernel bandwidth and the length of dictionary. [ABSTRACT FROM AUTHOR]

Within a transport model, we investigated the effects of the momentum dependence of the nuclear symmetry potential on the pion observables in central Sn + Sn collisions at 270 MeV/nucleon. To this end, the quantity Usym∞(ρ0)(i.e., the value of the nuclear symmetry potential at the saturation density ρ0and infinitely large nucleon momentum) was used to characterize the momentum dependence of the nuclear symmetry potential. With a certain L(i.e., the slope of the nuclear symmetry energy at ρ0), the characteristic parameter Usym∞(ρ0)of the symmetry potential significantly affects the production of π-and π+and their pion ratios. Moreover, by comparing the charged pion yields, pion ratios, and spectral pion ratios of the theoretical simulations for the reactions 108Sn + 112Sn and 132Sn + 124Sn with the corresponding data in the SπRIT experiments, we found that our results favor a constraint on Usym∞(ρ0)(i.e., -160-9+18MeV), and Lis also suggested within a range of 62.7 MeV

With the increasing proportion of wind turbines in power system, high-precision control of power generation directly affects the proportion of wind turbines connected to the grid. This paper takes the energy storage hydraulic wind turbines (ESHWTs) as the research object, the mathematical model of the hydraulic main transmission system and the hydraulic energy storage subsystem are established, and the energy transmission and control mechanism is obtained. The corresponding relationship between the output power of the hydraulic main drive system and the hydraulic energy storage subsystem and the variable motor speed is analyzed, based on the small signal linearization method, and the power transmission state is obtained with the variable motor speed fluctuation, and a double closed-loop power control strategy is proposed under the motor speed fluctuation, with the power control requirements after grid connection, Based on MATLAB software and 24 kW semi-physical simulation test platform of energy storage hydraulic wind turbine, the output power is accurately controlled and the power output problem is solved under the fluctuation of motor speed with the proposed control strategy.

Although a various of existing techniques are able to improve the performance of detection of the weak interesting signal, how to adaptively and efficiently attenuate the intricate noises especially in the case of no available reference noise signal is still the bottleneck to be overcome. According to the characteristics of sonar arrays, a multi-channel differencing method is presented to provide the prerequisite reference noise. However, the ingredient of obtained reference noise is too complicated to be used to effectively reduce the interference noise only using the classical linear cancellation methods. Hence, a novel adaptive noise cancellation method based on the multi-kernel normalized leastmean- square algorithm consisting of weighted linear and Gaussian kernel functions is proposed, which allows to simultaneously consider the cancellation of linear and nonlinear components in the reference noise. The simulation results demonstrate that the output signal-to-noise ratio (SNR) of the novel multi-kernel adaptive filtering method outperforms the conventional linear normalized least-mean-square method and the mono-kernel normalized leastmean- square method using the realistic noise data measured in the lake experiment. [ABSTRACT FROM AUTHOR]

To elucidate the interaction between hydrophilic lithospermic acid B and lipophilic tanshinone II A in rats.

The purpose of this study was to determine the effects of acute exercise on motor response inhibition using both behavioral and electrophysiological approaches.

An efficient hybrid time reversal (TR) imaging method based on signal subspace and noise subspace is proposed for electromagnetic superresolution detecting and imaging. First, the locations of targets are estimated by the transmitting-mode decomposition of the TR operator (DORT) method employing the signal subspace. Then, the TR multiple signal classification (TR-MUSIC) method employing the noise subspace is used in the estimated target area to get the superresolution imaging of targets. Two examples with homogeneous and inhomogeneous background mediums are considered, respectively. The results show that the proposed hybrid method has advantages in CPU time and memory cost because of the combination of rough and fine imaging. [ABSTRACT FROM AUTHOR]

According to a brand of heavy truck’s under protection device, using CATIA surface modeling functions , this article assessed the performance of the rear under-run protection device. Study the performance of the rear under-run protection device by doing width offset collision simulation. A new energy absorption type under-run protection device is designed which can improve the energy absorption property. By vehicle rear-end collision simulations the optimized feasibility of protective devices is verified.

Three dimensional (3D) geologic modeling is used to study the reservoir quantitatively from a three-dimensional angle, and its core is the prediction to reservoir of multi-disciplinary integration, quantitative and visualization. Compared with traditional reservoir research, it has a significant advantage. This paper makes geological modeling research and builds structural models sedimentary micro-facies models and phased property model for Hei46 block of Daqingzi oilfield by utilizing 3D geologic modeling technique and petrel software on the basis of integrated using of geology, logging, oil production test, production of dynamic information, thus it provide a reliable basis for reservoir's development and adjustment.

Effects of Zr addition on the microstructure, mechanical and electrochemical properties of Al–Mn–Si–Zn alloy were investigated. Transmission electron microscopy (TEM) observations reveal that, in as-annealled state, the precipitates in the Zr-containing alloy are finer and more dispersive than those in the Zr-free alloy. Whereas, in simulated brazing state, a weaker precipitation is found in the Zr-containing alloy. Tensile testing results indicate that, with Zr additon, comprehensive mechanical properties of the as-annealed alloys could be significantly improved but weakened for the simulated brazing alloy. Electrochemical testing results reveal that, with Zr addition, the corrosion resistance of the as-annealed alloy decreases. However, after the simulated brazing treatment, such a negative effect of Zr element on the corrosion behavior of the alloy could be negligible.

According to the structural features of 3-D braided composites, the whole structure is divided into three types of sub-unit cells, these are the interior unit cell, the surface unit cell and the corner unit cell. Considering the bending of fiber bundle and the deformation of cross-section which are caused by the space fiber extrusion and twist together, the corresponding geometric analysis models for every type of sub-unit cell are established, and the engineering elastic constants of the 3-D braided composites are predicted. The results show that the calculated results well agree with the experimental results, and the effectiveness of the model is verified.

Welding residual stresses between 12Cr1MoV and P91 steel pipes were analyzed by experiment and finite element method (FEM). Both measured hoop and axial stresses are in general agree with the simulation results. Meanwhile, to examine the effect of start/stop welding position on residual stresses, a simulation model whose welding passes all started at the same location during multi-pass welding was compared with a model whose start/stop positions were uniformly distributed along circumferential direction of the dissimilar pipe. The results show that higher residual stresses occurred near the superimposed start/stop position than the steady region when calculated by the model whose welding passes all started at the same location. Whereas, start/stop welding positions which are distributed uniformly along the circumferential direction of the pipe can significantly relieve this effect, correspondingly leading to a more uniform residual stress distribution around the multi-pass welded dissimilar pipe.

Because reinforced-fiber has characteristic of single step forming in three-dimensional braided composites, analysis of mechanical performance is very different from laminates. This paper proceeds from the micro-structure of 3-D braided composites, some review and research are presented detailedly, and the several model’s merit and demerit are analyzed, which can conduct dynamicists to choose reasonable numerical model. The mechanical performance can be predicted accurately, and the next research can be guided using above analysis.

The core of the numerical manifold method (NMM) is a two-mesh problem description. Two meshes are employed in an analysis: the mathematical mesh provides the nodes for building a finite covering of the solution domain, while the physical mesh provides the domain of integration. The NMM can deal with the continuum and discontinuous problem, and has been applied to the rock mechanics and engineering widely. This paper introduces the research progress of the NMM in the basic theory and application aspects. The adaptive mesh generation of NMM is discussed. The adaptive finite cover mesh reconstruction technology is given.

The paper studied B-pillar crashworthiness in the car side impact by modifying CAD model of a domestic car. MDB is builded according to ECER95 regulation and a car side impact model is established finally. And the paper made simulation analysis and solve for the model based on HyperMesh and LS-DYNA. According to simulation analysis, focusing on the insufficient crashworthiness of B-Pillar two schemes were put forward: one was to change the B-pillar thickness; The other was to change the B-pillar materials.The results show that simply increase thickness is not feasible and changing the steel to aluminum alloy is feasible which greatly improved crashworthiness.

In the present study, Ti (C,N)/Al2O3 nanocomposite ceramic die material was fabricated through adding nanosize Ti (C,N) powders into micrometer Al2O3 matrix by vacuum hot-pressing technology. Effects of the hot press sintering process on mechanical property and microstructure of the nanocomposite ceramic die material were investigated. The optimum hot-pressing technology with the sintering temperature of 1650°C, time duration of 15min and pressure of 30MPa was achieved. The microstructural morphology of the material was also analyzed. It reveals that the intergranular/intragranular microstructure and the resulted intergranular/transgranular fracture mode are the main causes for strengthening and toughening in the nanocomposite ceramic die material.

In this paper a three-dimensional tubular braided carbon/carbon composite model is presented, the calculated formula of the fiber volume fraction is deduced and the related performance parameters are calculated. Comparisons of displacements and stresses for the thermo-mechanical coupling are analyzed. The simulation results can help designers to analyze material property.