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This paper presents a highly reliable direct-contact electrostatic RF MEMS switch. To enhance the reliability, the contact structure of the switch is designed into a circular shape, and the bottom contact surface is covered by a hard metal Pt layer. In addition, a high resistance silicon cap is used for hermetic packaging of the switch structure. By theoretical calculation and FEM simulation, parameters of the switch structure as well as its packaging are co-designed and optimized. During fabrication, the circular contact structure is formed by a three-step etching process; and after fabrication, the silicon hermetic packaging is realized by epoxy bonding and multi-step dicing process. The measured insertion loss and isolation of the switch with package is −0.41@20 GHz, and −20.9@20 GHz. Due to the optimized design, the RF performance of the switch remains almost unchanged before and after packaging. The measured driving voltage is 50–60 V, and the ON/OFF switching time is 25 μs/5 μs. The lifetime test shows that the switch passes the 2.6 billion times hot switching at the working power of 25 dBm. Finally, the switch also shows good performances in package leak rate test.

Generally, ultrasonic propagation in ultrasonic non-destructive testing is regarded as a linear process, during which the interaction between ultrasonic and measured material is rarely considered. In this study, the mechanisms of ultrasonic propagation in viscoelastic poly(ethylene oxide) aqueous solution and the interaction between ultrasound and fluid are investigated. A theoretical model of ultrasonic propagation in a viscoelastic fluid is established, in which the body force from ultrasonic waves is added to the fluid momentum equation, and the viscoelasticity of the fluid is described by the Oldroyd-B model. The simulation results for the ultrasonic reflection coefficient at the solid–liquid boundary and the attenuation coefficient based on the multi-physics coupling method are experimentally verified. The results of this study show that the ultrasonic absorption coefficient at low frequencies from 2.25 to 7.5 MHz exhibits frequency dependence through ultrasonic relaxation spectroscopy. The simulation results of the velocity of disturbed flow during ultrasonic propagation show that the viscosity of the solution has a greater impact on the disturbance than the relaxation time, and the phase angle difference between the stress and strain also shows that the viscosity is the main factor affecting the ultrasonic propagation.

With the rapid development of our economy, the market of economic exchange rates between our country and other countries has also fluctuated. This paper analyzes the volatility of exchange rates among members of the Shanghai Cooperation Organization. The result shows that the economic volatility and exchange rate volatility among its members have strengthened gradually, and the courseware Shanghai Cooperation Organization has been developing steadily.

We investigate N 2 + air lasing at 391 nm, induced by strong laser fields in a nitrogen glow discharge plasma. We generate forward N 2 + air lasing on the B 2 Σ u + ( v ′ = 0 ) – X 2 Σ g + ( v ″ = 0 ) transition at 391 nm by irradiating an intense 35-fs, 800-nm laser in a pure nitrogen gas, finding that the 391-nm lasing quenches when the nitrogen gas is electrically discharged. In contrast, the 391-nm fluorescence measured from the side of the laser beam is strongly enhanced, demonstrating that this discharge promotes the population in the B 2 Σ u + ( v ′ = 0 ) state. By comparing the lasing and fluorescence spectra of the nitrogen gas obtained in the discharged and laser-induced plasma, we show that the quenching of N 2 + lasing is caused by the efficient suppression of population inversion between the B 2 Σ u + and X 2 Σ g + states of N 2 + , in which a much higher population occurs in the X 2 Σ g + state in the discharge plasma. Our results clarify the important role of population inversion in generating N 2 + air lasing, and also indicate the potential for the enhancement of N 2 + lasing via further manipulation of the population in the X 2 Σ g + state in the discharged medium.

In the non Gaussian background modelled by compound Gaussian distribution, a variety of distributed target detectors are addressed. Firstly, the detection statistics of different detectors are given. Then, the detection performance of five detectors is compared when the non Gaussian clutter covariance matrix is known. Secondly, when the non Gaussian clutter covariance matrix is unknown, a two-step architecture is adopted. Based on the same estimation method for non-Gaussian clutter covariance matrix structure, seven adaptive distributed target detectors are introduced and compared. Finally, through comparative analyses, the applicable conditions and application range of different detectors are summarized, which provide a theoretical reference for the practical application of radar target detection.

The manganese dioxide (MnO2) is a material that has broad application prospects and economic value, which is used in various fields. However, the poor conductivity, less active sites and the easy collapse of the structure during the reaction, limit application. In this paper, three kinds of MnO2 were prepared by simple method, α-MnO2, β-MnO2, and γ-MnO2. And the properties of the sample were further analyzed by Brunauer-Emmett-Teller (BET), X-ray diffffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX) and fourier transform infrared spectroscopy (FTIR). Then α-MnO2 was chosen as the precursor of this study. Three different ratios of transition metal Ni and Co are respectively loaded with α-MnO2. Electrodes made of 7 different samples including α-MnO2, complete cyclic voltammetry test. Results show that: (1) α-MnO2 is not easy to collapse and suitable for precursor; (2)the addition of metal Ni and Co increases the specific surface area of the material to varying degrees. Co@a-MnO2-2 has the highest specific surface area and porosity, which can provide more active sites when applied; (3)all seven samples have good capacitance characteristics. The best is Co@a-MnO2-0.5, but Co@a-MnO2-2 is very close to Co@a-MnO2-0.5. Comprehensive analysis, the best ratio for this study is Co@a-MnO2-2.

Based on the analysis of the machining process characteristics for special slender shaft work-piece, considering the increase in taper turning efficiency and accuracy, a new clamping scheme for machining both ends of slender shaft is put forward, which also includes using pulling tail-stock instead of traditional pushing, using follow-manipulator instead of follow-rest. Following the clamping scheme, the dual drive device, the tail-stock with pulling device and the manipulators are designed, then the parts are integrated into the special lathe for taper turning slender shaft.

A 16-channel distributed-feedback (DFB) laser array with a monolithic integrated arrayed waveguide grating multiplexer for a wavelength division multiplex-passive optical network system is fabricated by using the butt-joint metal organic chemical vapor deposition technology and nanoimpirnt technology. The results show that the threshold current is about 20–30 mA at 25°C. The DFB laser side output power is about 16 mW with a 150 mA injection current. The lasing wavelength is from 1550 nm to 1575 nm covering a more than 25 nm range with 200 GHz channel space. A more than 55 dB sidemode suppression ratio is obtained.

A monolithically integrated four-channel λ/4 phase shift distributed feedback (DFB) laser array with a 4 × 1 multimode interference combiner is designed and fabricated using nanoimprint lithography. The threshold currents of the lasers are less than 10 mA, which are as good as a discrete DFB laser. Moreover, the side-mode suppression ratio is also better than 50 dB. The channel space is about 200 GHz for dense wavelength division multiplexing applications in an 1.55 μm system.

Since there are dark matter particles (neutrino) with mass about 10^(-1)eV in the universe, the superstructures with a scale of 10^(19) solar mass [large number A is about 10^(19)] appeared around the era of the hydrogen recombination. The redshift z distributions of quasars support the existence of superstructures. Since there are superstructures in the universe, it is not necessary for the hypothesis of dark energy. While neutrino is related to electro-weak field, the fourth stable elementary particles (delta particle) with mass about 10^(0)eV is related to gravitation-"strong" field, which suggests p + anti(p)--> n/anti(n) + anti(delta particle)/(delta particle) and that some new meta-stable baryons appeared near the TeV region. Therefore, a twofold standard model diagram is proposed, and related to many experiment phenomena: The new meta-stable baryons' decays produce delta particles, which are helpful to explain the Dijet asymmetry phenomena at LHC of CERN, the different results for the Fermilab's data peak, etc; However, according to the (B-L) invariance, the sterile "neutrino" from "the event excess in MiniBooNe" can not be the fourth neutrino but rather the delta particle; We think that the delta particles are related to the phenomenon about neutrinos FTL, and that anti-neutrinos are faster than neutrinos. FTL is also related to the cosmic inflation, singular point disappearance, and abnormal red shift of SN Ia. Some experiments and observations are suggested.

In this work, we have reported for the first time a facile route for developing solution-processed Al2O3 film at a greatly reduced processing temperature and studied its applications in producing inverted polymer solar cells (PSCs). These PSCs using Al2O3 thin film as the electron-extraction layer demonstrated improved diode characteristics and achieved a 20% higher power conversion efficiency than devices using the conventional ZnO buffer layer. Furthermore, the low temperature processing of the Al2O3 film makes it compatible with fabrication of flexible organic electronic devices based on plastic substrates.

Phase-locking behaviors are closely relevant to arrhythmias. The traditional approach to investigate the subject is the phase resetting map, which interprets phase-locking via the view point of nonlinear mapping dynamics. In the present paper, the Fourier series approach is developed. By decomposing the traces of the transmembrane voltage and total ionic current into Fourier series, the effect of the stimulations on the oscillation period could be revealed analytically. The following well-studied problems are reinvestigated: i) the phase resetting property of the cell; ii) the bifurcations between phase-locking zones; iii) phase-locking behaviors of a pair of coupled cells, which is relevant to behaviors of the sinoatrial node tissue. The work may provide a deeper insight into the subject and a simple method to predict sinoatrial node phase-locking dynamics.

A 16-channel monolithically integrated index-coupled distributed-feedback laser array has been fabricated using nanoimprint technology. Selective lasing wavelengths with 300 and 100 GHz frequency space are obtained. The fine tenability for an individual laser in the array is achieved with a Ti–Au thin-film resistor integrated on the chip. The typical threshold current is between 10 and 15 mA without current in the thin-film resistor. The optical output power of each channel is about 6 mW at an injection current of 70 mA.

A novel tunable laser with digital concatenated grating reflectors, which has a flatter envelope of reflection peaks, is designed and fabricated. The key concept of the approach is to utilize multi-sampled gratings which have different Bragg wavelengths and the same sampling period. The difference of each Bragg wavelength is integer multiple of the space between the peaks of sampled gratings. Here, nanoimprint lithographic technology is used to fabricate the complex gratings. The typical threshold current of the tunable laser is 34 mA, and the tuning range is larger than 32 nm. The non-uniformity of the output power is less than 2 dB.

In this paper we investigate spatiotemporal pattern formation in excitable media with only a long-range link. Besides the trivial solutions of spiral patterns, we find the asymptotic self-sustained target waves in the autonomous tissues. The wave source supporting this kind of new pattern is the oscillatory one-dimensional Winfree-loop self-organized under the presence of a long-range link, which is explored by the dominant phase-advanced driving method. Based on this understanding we can effectively regulate the oscillations of excitable media by suitably arranging the long-range link, including construction of self-sustained target waves with controllable period and wave length, or manipulation of system states between different patterns.

Information storage in many functional subsystems of the brain is regarded by theoretical neuroscientists to be related to attractors of neural networks. The number of attractors is large and each attractor can be temporarily represented or suppressed easily by corresponding external stimulus. In this letter, we discover that complex networks consisting of excitable nodes have similar fascinating properties of coexistence of large numbers of oscillatory attractors, most of which can be labeled with a few nodes. According to a simple labeling rule, different attractors can be identified and the number of labelable attractors can be predicted from the analysis of network topology. With the cues of the labeling association, these attractors can be conveniently retrieved or suppressed on purpose.

Evolutionary Structural Optimization (ESO) and its later version bi-directional ESO (BESO) have gained widespread popularity among researchers in structural optimization and practitioners in engineering and architecture. However, there have also been many critical comments on various aspects of ESO/BESO. To address those criticisms, we have carried out extensive work to improve the original ESO/BESO algorithms in recent years. This paper summarizes some of the latest developments in the BESO method for topology optimization of continuum structures. Numerical results show that the ESO/BESO solutions agree well with those of other well-established topology optimization methods. It indicates that the current BESO method has great potential to become a robust and efficient design tool for practical applications in engineering and architecture.

Frequency optimization is of great importance in the design of machines and structures subjected to dynamic loading. When the natural frequencies of considered structures are maximized using the Solid Isotropic Material with Penalization (SIMP) model, artificial localized modes may occur in areas where elements are assigned with low density values. In this paper, a modified SIMP model is developed to effectively avoid the artificial modes. Based on this model, a new bi-directional evolutionary structural optimization (BESO) method combined with rigorous optimality criteria is developed for topology frequency optimization problems. Numerical results show that the proposed BESO method is efficient and convergent and solid-void or bi-material optimal solutions can be achieved for a variety of frequency optimization problems of continuum structures.