Effect of Al-deposition on erosion resistance of plasma sprayed thermal barrier coating

A columnar Al film was firstly deposited on the top of 7%Y2O3？stabilized zirconia （7YSZ） ceramic coating in thermal barrier coating （TBC） system by magnetron sputtering. A vacuum treatment was then carried out at 700 °C for 1 h and 900 °C for 5 h to improve the erosion resistance of Al-deposited TBC. Aα-Al2O3 layer was in situ synthesized on the top of 7YSZ coating via vacuum heat treatment. The microstructure evolution of Al-deposited TBC illustrated that a loose surface-layer and a dense sub-layer formed on the top of 7YSZ coating after vacuum treatment. The phase structures of the as-sprayed TBC and the Al-deposited TBC after vacuum heat treatment were characterized by X-ray diffraction （XRD） and transmission electron microscope （TEM） assisted with focused ion beam （FIB）. Particulate erosion resistances of the as-sprayed TBC and treated TBC were compared at room temperature. In addition, erosion mechanism and schematic diagram were proposed. The results show that the Al-deposited TBC after vacuum heat treatment has better particulate erosion resistance than the as-sprayed one.

覆盖件模具特征约束模型及其应用

针对覆盖件模具设计的复杂性、灵活性、经验性、模糊性.提出了一种基于特征的分层的约束模型。覆盖件模具特征分为冲压工艺特征、功能组合特征和基元特征三个层次,与此相应建立了分层的约束网,并叙述了其推理过程。

Adaptive Layout Partitioning for Dark Field Alternating Phase-Shift Mask Design

A new partitioning methodology is presented to accelerate 130nm and beyond large scale alternating phase shift mask(Alt PSM) design flow.This method deals with granularity self adaptively.Phase conflicts resolution approaches are described and strategies guaranteeing phase compatible during layout compaction are also discussed.An efficient CAD prototype for dark field Alt PSM based on these algorithms is implemented.The experimental results on several industry layouts show that the tool can successfully cope with the rapid growth of phase conflicts with good quality and satisfy lower resource consumption with different requirements of precision and speedup.

Wear mechanism and serious wear position of casing pipe in vertical backfill drill-hole

Vertical backfill drill-hole is usually a key project in an underground mine with backfill method and can be easily damaged by impact of backfill slurry.Observation of the damaged vertical backfill drill-holes in Jinchuan Nonferrous Metal Corporation（JNMC）,Gansu Province,China,given by a digital drill-hole video camera,indicated that there usually exist serious wear zones in casing pipe in vertical backfill drill-hole（CVBH）.It was suggested that serious wear position of CVBH should be located at an interface between air and solid-liquid mixture within CVBH.Backfill slurry falls freely and impacts the wall of CVBH near the interface with great momentum and energy coming from high speed free fall of backfill slurry.The depth of serious wear position of CVBH,i.e.,free fall height of backfill slurry in CVBH,can be estimated by the height of vertical backfill drill-hole,the length of horizontal pipeline,the density of slurry and the hydraulic gradient of pipeline system.A case study indicated that the estimation equation of serious damage depth of CVBH was of enough accuracy and was helpful for daily maintenance and management of vertical backfill drill-hole.

Effect of electropulsing on dislocation mobility of titanium sheet

To investigate the effect of the electropulsing on dislocation mobility,specimens cut from the cold-rolled titanium sheet were treated by high density electropulsing with the maximum current density of 7.22,7.64,7.96 kA/mm 2 ,pulse period 110μs.The internal friction and elastic modulus were measured by a dynamic mechanical analyzer（DMA）.When strain amplitude lowers a certain critical one,the damping of the electropulsed titanium sheet is lower than that of the cold-rolled one.When the strain amplitude exceeds the critical one,the damping of the electropulsed titanium sheet is extraordinarily higher than that of the cold-rolled or conventional annealed one.Furthermore,it is found that the damping peak of the electropulsed titanium sheet shifts to lower temperature compared with the conventional annealed one.It is demonstrated that the electropulsing treatment can decrease dislocation tangles and enhance dislocation mobility.

Transmission cable fault detector based on waveform reconstruction

In order to improve the accuracy of cable fault position location at a low cost and make the testing results intuitive, a cable fault detector based on wave form reconstruction is designed. In this detector, the cable fault position is located based on the time-domain pulse reflection （TDR） principle. A pulse waveform is injected in the tested cable, and a high-speed comparator with changeable reference voltages is used to binarize the test pulse waveform to a binary sequence on a certain voltage. Through scanning the reference voltage in a full voltage range, multi-sequences are acquired to reconstruct the pulse waveform transmission in the cable, and then the pulse attenuation feature, electrical open circuit fault, electrical short circuit fault, and the fault position of the cable are diagnosed. Experimental results show that the designed cable fault detector can determine the fault type and its position of the cable being tested, and the testing results are intuitive.

Asymmetry in the Strong-field Photodetachment of H- by Linearly Polarized Few-cycle Pulses

Photodetachment of H- irradiated by linearly polarized few-cycle laser field is investigated by time-dependent SchrSdinger equation numerically. The photo-electron left-right asymmetry parameter as a function of carrier-envelop （CE） phase of few-cycle pulses is attained. We confirm the asymmetry of photoelectron distribution in H- photodetachment and find that the maximal asymmetry parameter of H- is equal to that of H atom under the same conditions but the corresponding CE phases are quite different. Thus a CE phase shift appears. Compared to that of H atom and field free electron, the zero asymmetry CE phase shift is sensitively affected by Coulomb field. The Coulomb effect on the asymmetry of H- photodetachment mainly behaves in the CE phase shift of H- instead of the amplitude of asymmetry parameter curve.

Frequency synthesizer for DRM/DAB/AM/FM RF front-end

This paper describes a wideband low phase noise frequency synthesizer.It operates in the multi-band including digital radio mondiale DRM digital audio broadcasting DAB amplitude modulation AM and frequency modulation FM .In order to cover the signals of the overall frequencies a novel frequency planning and a new structure are proposed. A wide-band low-phase-noise low-power voltage-control oscillator VCO and a high speed wide band high frequency division ratio pulse swallow frequency divider with a low power consumption are presented.The monolithic DRM/DAB/AM/FM frequency synthesizer chip is also fabricated in a SMIC＇s 0.18-μm CMOS process.The die area is 1 425 μm ×795 μm including the test buffer and pads. The measured results show that the VCO operating frequency range is from 2.22 to 3.57 GHz the measured phase noise of the VCO is 120.22 dBc/Hz at 1 MHz offset the pulse swallow frequency divider operation frequency is from 0.9 to 3.4 GHz.The phase noise in the phase-locked loop PLL is-59.52 dBc/Hz at 10 kHz offset and fits for the demand of the DRM/DAB/AM/FM RF front-end. The proposed frequency synthesizer consumes 47 mW including test buffer under a 1.8 V supply.

Low-Density Parity-Check Codes for Noncoherent UWB Communication Systems

In order to guarantee reliable data transmission, powerful channel coding techniques are usually required in noncoherent ultra-wideband(UWB) communication systems. Accordingly, several forward error correction(FEC) codes, such as Reed-Solomon and convolutional codes have been used in noncoherent UWB systems to improve the bit error rate(BER) performance. In this paper, low-density parity-check(LDPC) codes are further studied as more powerful FEC candidates for noncoherent UWB systems. Two LDPC codes and the corresponding decoding procedures are presented for noncoherent UWB systems. Moreover, performance comparison between the LDPC codes and other FEC codes are provided for three major noncoherent UWB communication systems, namely, noncoherent pulse position modulation(NC-PPM), transmitted reference(TR) and transmitted reference pulse cluster(TRPC). Both theoretical analysis and simulation results show that the two investigated LDPC codes outperform other existing FEC codes with limited penalty in terms of complexity and therefore they are promising FEC candidates for noncoherent UWB systems with low-cost and low-power consumption.

A Novel Low Density Parity Check Coded Differential Amplitude and Pulse Position Modulation Free-Space Optical System for Turbulent Channel

Based on the proposed partly equidifferent mapping and its specific Differential Amplitude and Pulse Position Modulation(DAPPM) demodulation, a modified FSO scheme for turbulent channel is designed and analyzed. The novel Low Density Parity Check(LDPC) coded 4×4 and 4×8 DAPPM Free-Space Optical communication(FSO) system is constructed. The Monte Carlo simulation results show approximately 2d B transmit power reduction against classical LDPC-DAPPM at the identical Bit-Error-Rate in strong turbulent channel. The proposed partly equidifferent mapping is compatible with other modulations, so it enables widespread adoption in other coded FSO systems.

Chaotic pulse position modulation ultra-wideband system based on particle filtering

Traditional chaotic pulse position modulation(CPPM)system has many drawbacks.It introduces delay into the feedback loop,which will lead to divergence of chaotic map easily.The wrong decision of data will cause error propagation.Mismatch of parameters and synchronization error between the receiver and transmitter will arouse high bit error rate.To solve these problems,a demodulation algorithm of CPPM based on particle filtering is proposed.According to the mathematical model of the system,it tracks the real signal by online separation in demodulation.Simulation results show that the proposed method can track the true signal better than the traditional CPPM scheme.What's more,it has good synchronization robustness,reduced error propagation by wrong decision and low bit error rate.

A NEW MODULATION SCHEME FOR IR-UWB COMMUNICATION SYSTEMS

Since the poor performance of orthogonal binary Pulse Position Modulation (PPM) compared with binary Pulse Amplitude Modulation (PAM), this paper presents a new modulation scheme named Pulse Width Modulation (PWM) for Impulse Radio Ultra-WideBand (IR-UWB) communication systems. This modulation scheme uses pulses with equal amplitude and different widths to carry different information. The receiver employs differences between similarity coefficients among these pulses to distinguish different information. Both theoretical analysis and simulation results verify that this novel scheme has a Signal to Noise Ratio (SNR) gain of about 1.75 dB compared with or- thogonal binary PPM, and has an SNR loss of about 1.4 dB compared with binary PAM. Although both the theoretical analysis and simulations are based on time-hopping multiple access, this modulation scheme can also be applied to other accessing techniques of UWB communication systems.

Removal of SO_2 and NO_x by Pulsed Corona Combined with in situ Ca(OH)2 Absorption

Removal of SO2 and NOx by pulsed corona combined with in situ alkali absorption was experimentally investigated.In the reactor,a plate-wire-plate combination is devised for generating pulsed corona and then alkaline absorbent slurries were introduced into the reactor by a continuous band conveying system to capture the gaseous reaction products.It was found that both SO2 and NO could be removed by corona combined with in situ alkali absorption.The removal of SO2 increased to 75%with the corona discharge,compared with 60%removal only with Ca(OH)2 absorption.About 40%removal of NO was reached by pulsed corona combined with in situ Ca(OH)2 absorption.It was found that SO2 and NO in the gas stream are oxidized to SO3 and NO2 by pulsed corona respectively,and then absorbed by the alkali in the reactor.The removals of SO2 as well as NO were higher with Ca(OH)2 as the absorbent,compared with using CaCO3 or ZnO.

Study on Water-Soluble Organic Reducing Substances. I. Determination of Organic Reducing Substances by Differential Pulse Voltammetry

A new method was proposed for study of organic reducing substances in soils. According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances, the working conditions of differential pulse voltammetry (d.p. v.) for determining the organic reducing substances produced during the processes of the anaerobic decomposition of plant materials were established with a glass carbon electrode as working electrode, 1 M Ag-AgCl electrode with large area as reference electrode, 0.2 M NH4AC as supporting electrolyte and pH buffer solution, pulse amplitude (AE) of 25 mV, scan rate at 2 mV·S-1and scan potential ranging from -0.5 to +1.2 voltage(vs. M Ag-AgCl). The peak current proportional to the concentration of reducing substances, and the characteristic peak potential of each organic reducing substance were regarded as the quantitative and qualitative base, respectively. These results obtained under the conditions mentioned above directly reflect both the reducing intensity and capacity of the organic reducing system in soils.

A Novel Non-Equidifferent Optical APPM Mapping Scheme for Strong Turbulent Atmospheric Channel

An optical Amplitude and Pulse Position Modulation(APPM) mapping scheme for strong turbulent atmospheric channel is proposed to optimize Bit Error Rate(BER) performance.In this scheme,a nonequidifferent amplitude series is designed based on quantitative BER analysis of the specific A×M APPM demapping procedures containing time slot selection and amplitude decision in selected time slot,which are different from traditional ones.Simulation results of 4×4,4×8 and 4×16 APPM show 4,3.4 and 6.9 d B SNR gain against traditional APPM scheme respectively.Thus significant BER performance improvement is achieved which helps to enhance reliability of freespace optical communication systems.

On the Mystery of the Interpulse Shift in the Crab Pulsar

A new mechanism of radiation emission in the polar gap of a pulsar is proposed. It is the curvature radiation emitted by positrons moving towards the surface of the neutron star along inclined magnetic field and reflected from the surface. Such radiation interferes with transition radiation emitted from the neutron star when positrons hit the surface. Proposed mechanism explains the mystery of the interpulse shift in the Crab pulsar at high frequencies discovered by Moffett and Hankins twenty years ago. We have found also reflected energy flux and spectrum, discussed coherence and disappearance of interpulse shift with increase of frequency.

Note on Implementation of Three-Qubit SWAP Gate

In this paper, the synthesis and implementation of three-qubit SWAP gate is discussed. The three-qubit SWAP gate can be decomposed into product of 2 two-qubit SWAP gates, and it can be realized by 6 CNOT gates. Research illustrated that although the result is very simple, the current methods of matrix decomposition for multi-qubit gate can not get that. Then the implementation of three-qubit SWAP gate in the three spin system with Ising interaction is investigated and the sequence of control pulse and drift process to implement the gate is given. It needs 23 control pulses and 12 drift processes. Since the interaction can not be switched on and off at will, the realization of three-qubit SWAP gate in specific quantum system also can not simply come down to 2 two-qubit SWAP gates.

GiT-based structural geologic feature analysis of the southern segment of Longmenshan fault zone for earthquake evidence

The Longmenshan fault is a thrust fault which runs along the base of the Longmen Mountains in Siehuan province, southwestern China. The southern segment of the fault had two distinct responses to the Ms 8 Wenehuan and Ms 7 Lushan earthquakes. This study determines characteristics of the structural geology of the Longmenshan fault to evaluate how it influenced the two aforementioned earthquakes. This research was done within a Geo- information Technologies （GiT） environment based on multi-source remote sensing and crustal movement data extracted from the Global Positioning System （GPS）. The spatial distribution of the southern segment of the Longmenshan fault zone was comprehensively analyzed to study both earthquakes. The study revealed that the Wenehuan and Lushan earthquakes occurred on two relatively independent faults. In addition, there was a nearly constant-velocity crustal movement zone between the two epicenters that probably had a compressive stress with slow motion. Furthermore, the central fault and a mountain back fault gradually merged from north to south. The Lushan earthquake of the Wenchuan earthquake. was not an affershock The research showed that fault zones within 30-50 km of State Highway 318 are intensive and complex. In addition, crustal movement velocity decreased rapidly, with a strong multi-directional shear zone. Thus, activity in that zone was likely stronger than in the northern part over the medium to long term.

Fault Diagnosis and Phase Disposition Reconfiguration of a 5-Level Double-Boost Power Factor Corrector with Fault-Tolerant Capability

A 5-level PFC （power factor correction） topology with fault-diagnostic and fault-tolerant capability is proposed and compared to known structures. It is derived from a 3-level non differential double-boost PFC including fly-cap cells. The series-connection of the two low-voltage switching-cells is decoupled by a single flying capacitor that provides a direct fault-tolerant capability and a post-failure operation increasing the availability of converter. The monitoring of the voltages across flying capacitors allows a rapid detection and localization either for open circuit failure or short-circuits failure. A PWM （pulse width modulation） phase-disposition type reconfiguration is also used and presented in order to optimize both normal operation and post-fault continuation. The design and the most important features are highlighted thanks to a digital control frame and a mock-up rated to： AC voltage network 115 V-load 400 V-nominal power 4 kW-switching frequency 62 kHz.

Modified nonlinear chirp scaling algorithm for curvilinear trajectory synthetic aperture radar

The original nonlinear chirp scaling(NCS) algorithm was extended for high precision processing of the highly squinted curvilinear trajectory synthetic aperture radar(CTSAR).Based on the analysis of slant range model and the frequency spectrum characteristics of the echo signal,a novel nonlinear chirp scaling function and more complex phase compensation factors with both velocity and acceleration parameters were proposed in the new algorithm for accommodation to curvilinear trajectory.The processing flow and computational complexity of modified NCS algorithm were fundamentally the same as the original NCS algorithm.However,the higher order phase compensation,range cell migration correction(RCMC) and range-variant secondary range compression(SRC) caused by the non-linear aperture and the severe range-azimuth coupling were accomplished accurately and efficiently without interpolation.Simulation results show that data acquired with a curvilinear aperture and a squint angle up to about 50° for X-band can be processed with no evident degradation of impulse response function.