In this paper,directional porous SiC ceramics were prepared by adding coal slime.The formation mechanism of oriented pores and the effect of sintering system on the properties of the products were discussed.The results show that the SiC particles generated by the carbothermal reduction reaction inside the coal slime promote the formation of tubular pores and columnar structures.Porous carbon that does not participate in the arbothermal reduction reaction effectively absorbs silicon vapor in the mixed gas and inhibits the formation of gradient pores.TiO 2 components react with porous carbon at high temperature to generate TiC reinforcement phase.The reaction of aluminum oxide melt with SiC and residual carbon results in the formation of columnar structures with rounded surfaces,which also effectively consumes residual porous carbon.The increase of sintering temperature and the extension of holding time effectively promote the material transfer,and further increase the porosity,loss on ignition and pore size.The addition of coal slime provides a large number of SiC and carbon sources for recrystallization,which further inhibits the volatilization of recrystallized SiC particles.

A method of designing and fabricating substrate-free Au/SiN x /Au metafilms as the terahertz (THz) absorber of metamaterial focal plane arrays (MFPA) is reported. The absorption was investigated by the finite integration method simulation and new explicit functions. The substrate-free structure was well fabricated by microelectromechanical system (MEMS) technology. The frequency-dependent absorption of MFPA was measured by THz time-domain spectroscopy (THz-TDS) system. It exhibits an extremely high absorptance of 98.7% at 1.36 THz. The absorption characteristic shows an asymmetric profile, which is well fitted with an Asymmetric Double Sigmoidal (Asym2sig) model. Our results show that the Au/SiN x /Au metafilms have potential in optical readout THz real-time imaging, and highly sensitive sensing applications.

A double-layer silicon-based stripline filter with a center frequency of 20.76 GHz and a bandwidth of 2 GHz was designed by using an aggressive space mapping (ASM) and fabricated with microelectromechanical systems (MEMS) technology. The measurements agreed well with simulation, showing efficiency and accuracy of the ASM algorithm. Over temperature range of -50 to 80 degrees C, the filter's performance such as insertion loss, bandwidth and central frequency were investigated and discussed, and the measured frequency drift is -55.5 ppm/degrees C and the bandwidth variation is +/- 4% over temperature range of -50 to 80 degrees C. At 150 degrees C after 1000 h of aging test, although the insertion loss of the filter slightly increased from 2.18 to 2.4 dB and the passband ripple deteriorated, the stopband rejection performance improved.

A high-performance microstrip lowpass filter with coplanar waveguide as the ports is proposed and analyzed. By cascading asymmetric hairpin resonators, a compact elliptic function low-pass filter with wide stop band was realized. The filter was optimized using aggressive space mapping algorithm, and finally a filter with a cut-off frequency of 11.8 GHz was obtained. Stop bandwidth with attenuation level better than -27 dB extends from 15.6 to 36 GHz. Also, the maximum insertion loss in the passband is 0.9 dB and the return loss is better than -22 dB. The filter is manufactured on the silicon wafer using micro-electromechanical systems process, and the measured results in good agreement with the simulation results.

针对单节点行人惯性定位算法中步长计算精度较低的问题,提出了一种基于多节点运动姿态信息融合的行人步长估计算法.首先,根据行走时足部节点Z轴加速度与X轴角速度的波峰、波谷值变化特征检测行人的步态;其次,通过腿部4个节点X轴角速度的波峰及波谷值变化特征,对足跟着地动作的识别进行约束;最后,结合行人双腿长度信息、步态检测结果及腿部俯仰角信息解算得到行人步长.实验数据表明,该步长估计算法能与身体多个部位的运动信息相结合,行人步长平均估计精度可达98.9％.

In this article, a compact embedded interdigital filter with six novel resonators and coplanar waveguide feeder is proposed. The novel resonator consists of a through silicon via and a microstrip line embedded in the substrate. The novel embedded interdigital filter is designed on a double-sided polished silicon wafer and optimized using aggressive space mapping. The center frequency of the filer is 5.9 GHz and the fractional 1 dB bandwidth is 33.9% (4.9-6.9 GHz). The insertion loss (IL) of the proposed filter is − 0.7 dB, and the return loss (RL) is −24 dbs. The proposed filter with a size of 4.5 mm X 6.5 mm has been verified in full-wave simulator HFSS, which can be mass-produced using MEMS technology.

为了解决惯性导航系统长航时累计误差和实时性问题,提出了一种基于因子图的多源信息融合算法.论文基于和积算法,采用了因子图模型进行基于最大后验概率的状态估计,计算变量的均值和方差完成数据融合,利用超宽带技术和视觉传感器对发生累积误差的惯性导航系统进行校准,完成误差修正.对信息融合算法进行了仿真,结果为:该算法各轴向的误差分别为0.36％和0.31％,解算时间为50 ms.该算法误差仅为惯性导航累计误差的1/3,实时性相较于其它算法更高.

Microelectromechanical system (MEMS) focal plane array (FPA) with optical readout offers exciting opportunities for real-time terahertz (THz) imaging. However, conventional FPA suffers from a low THz absorption ratio, which further decreases the performance of THz imaging. Here, we present a simple and scalable approach for the realization of THz focal plane metamaterial array with a relatively high absorption ratio. The key idea is to combine the advantages of substrate-free structures with metamaterial. A 100 x100 THz FPA with a 150 x 150 μm pixel is designed, fabricated, and characterized. The dependence of the THz absorption ratio on the thickness of SiNx dielectric substrate film is investigated. The fabricated FPA exhibits a 90.6 absorption at 1.36 THz, agreeing considerably with the theoretical simulation results. Our results imply that such a substrate-free THz focal plane metamaterial array enables the realization of THz imaging.

Substrate integrated waveguide (SIW) is a new structure for microwave transmission. In this paper, a planar folded sixth-order SIW filter is designed with aggressive space mapping (ASM) algorithm. Its center frequency is 22 GHz, 3 dB bandwidth 1 GHz, and in-band return loss 22 dB. The filter satisfies design specifications after four iterations, and is fabricated using micro-electro-mechanical systems (MEMS) technology with a chip size of 7.5 mm x 8.5 mm x 0.4 mm. Measurement results show that the center frequency of the filter measures at 22.2 GHz, 3 dB bandwidth at 1 GHz, insertion loss at 3.57 dB, return loss at 22 dB and out-of-band rejection at 40 dB.

文中提出一种双线极化、低剖面的新型通信基站天线,该天线的特点在于具有相对较低的剖面,同时在两端口间的隔离度和交叉极化比指标也相当优秀.它是由一块铝制圆形薄片、一个铝制边框和一块双面印刷电路板组成,印刷电路板的两边分别是具有一分二功能的Wilkinson功分器馈电网络和一个混合了T形结构的十字渐变缝隙.仿真和测试结果表明,该天线在关注的频段内具有小于-30 dB的端口隔离度,-10 dB带宽为806～1010 MHz.天线的水平面和垂直面半功率波束宽度分别为88.22°±3.38°和71.37°±5.25°,交叉极化比最高为-28.9 dB.除此之外,该天线还具有易于加工组装、成本低等许多优点,可以在现代通信系统中GSM和CDMA的频段内工作.

The auxiliary diagnosis and debugging of filters play an increasingly important role in the design of microwave filters, where aggressive space mapping (ASM) is one of the most commonly used debugging methods. This paper introduces ASM and designs a sixth-order two-layer microstrip interdigital filter with a center frequency of 20.4 GHz and a bandwidth of 1.6 GHz using ASM. The filter reached design indexes after seven iterations, which greatly reduces the number of simulations in the fine model, thereby saving time. It was fabricated with Micro-Electro-Mechanical Systems technology and the size of the chip is 7 mm x 3 mm x 0.8 mm. The measurement result was in good agreement with the simulation result.

The auxiliary diagnosis and debugging of filters play an increasingly important role in the design of microwave filters. In particular, aggressive space mapping (ASM) is one of the most commonly used debugging methods. This paper introduces ASM and designs a seventhorder microstrip interdigital filter with a center frequency of 24GHz and a fractional bandwidth of 25% with ASM. The filter reached design indexes after four iterations, which greatly reduces the number of simulations in fine model, thereby saving time. It was fabricated on high resistance silicon substrate and the size of the chip is 6.8mm × 2.4mm × 0.4mm. The measurement results show that the fabricated filter has a center frequency of 24GHz, a fractional bandwidth of 24.17%, an insertion loss of 1.95 dB, a return loss of 12 dB, and an out-of-band rejection of 40 dB.

This article presents the optimization design and simulation of a betavoltaic battery composed of a silicon p-n junction converter and a titanium tritide film as an isotope source. The self-absorption of beta particles emitted from the tritium radioisotope in the titanium tritide film and the energy deposition of beta particles in the silicon converter are investigated by the Monte Carlo simulation with the Geant4 radiation transport toolkit. The relationships between doping concentrations and basic parameters such as depletion region width, minority carrier diffusion length and leakage current of the PN junction are discussed through the calculation formulas. By optimizing the doping concentrations in the P-type and N-type regions, the optimized betavoltaic battery can maximize the output power and the conversion efficiency based on the energy deposition in the silicon. The results show that the optimal thickness of the titanium tritide film is about 0.7 mu m and the optimal doping concentrations of the battery with a PN junction depth of 50 nm are N-a = 5.75 x 10(19) cm(-3), N-d = 2.95 X 10(18) cm(-3). Under these parameters, the size 1 mm x 1 mm proposed battery with 2.9 mCi/mm(2) H-3 can achieve the output power 0.902 nW and the conversion efficiency 0.91%. The open circuit voltage, short circuit current and fill factor of the battery are 0.389 V, 3.03 nA and 0.766, respectively.

An optical readout focal plane array (FPA) usually has a differently tilted reflector/absorber at the initial state due to the micromachining technique. The angular deviation of the reflector/absorber has a strong impact on the optical sensitivity non-uniformity, which is a key factor which affects the imaging uniformity. In this study, a theoretical analysis has been developed, and it is found that the stress matching in SiO2-Aluminum (Al) bilayer leg could make a contribution towards reducing the optical sensitivity non-uniformity. Ion implantation of phosphorus (P) has been utilized to control the stress in SiO2 film. By controlling the implantation energy and dose, the stress and stress stability are modified. The optical readout FPA has been successfully fabricated with the stress-control technique based on P+ implantation. It is demonstrated that the gray response non-uniformity of optical readout FPA has decreased from 25.69% to 10.7%.

射频(RF)滤波器在4G移动通信(如Band 40波段)中具有广泛应用.描述了基于薄膜体声波谐振器(FBAR)技术的RF滤波器的设计和制作方法.体声波滤波器是由FBAR以T型结构级联的方式实现的.在滤波器的设计过程中,为了使仿真结果更接近于实际情况,采用考虑电极和衬底间耦合效应的改进的Mason模型对FBAR进行性能仿真和优化.最后,在8英寸(1英寸=2.54 cm) CMOS工艺线上对此滤波器进行了流片.测试结果表明,Band 40波段的体声波滤波器具有低的通带插入损耗(小于3 dB)、高的带外抑制(大于40 dB)和快速滚降特性.

In this paper, we present the simulation and fabrication of a thin film bulk acoustic resonator (FBAR). In order to improve the accuracy of simulation, an improved Mason model was introduced to design the resonator by taking the coupling effect between electrode and substrate into consideration. The resonators were fabricated by the eight inch CMOS process, and the measurements show that the improved Mason model is more accurate than a simple Mason model. The Q(s) (Q at series resonance), Q(p) (Q at parallel resonance), Q(max) and k(t)(2) of the FBAR were measured to be 695, 814, 1049, and 7.01% respectively, showing better performance than previous reports.

By combining substrate-free structures with anodic bonding technology, we present a simple and efficient micro-electro-mechanical system (MEMS) thermal shear stress sensor. Significantly, the resulting depth of the vacuum cavity of the sensor is determined by the thickness of the silicon substrate at which Si is removed by the anisotropic wet etching process. Compared with the sensor based on a sacrificial layer technique, the proposed MEMS thermal shear-stress sensor exhibits dramatically improved sensitivity due to the much larger vacuum cavity depth. The fabricated MEMS thermal shear-stress sensor with a vacuum cavity depth as large as 525 μm and a vacuum of 5 × 10−2 Pa exhibits a sensitivity of 184.5 mV/Pa and a response time of 180 μs. We also experimentally demonstrate that the sensor power is indeed proportional to the 1/3-power of the applied shear stress. The substrate-free structures offer the ability to precisely measure the shear stress fluctuations in low speed turbulent boundary layer wind tunnels.

A double-layer SIW band-pass filter has been introduced,in which the interdigital strip-lines structure was utilized to achieve resonant and the CPW coplanar waveguide was used as the input and output lines. The chip size of the millimeter-wave filter designed is as small as 7 mm×3.5 mm×0.8 mm. Then the filter was simulated and optimized by using a 3D electro-magnetic field analysis software. The simulation results show that the central fre-quency,bandwidth,and insertion loss of the designed filter respectively are 10.6 GHz,2.5 GHz and 2 dB,which ful-ly meet the design aims. Finally,the fabrication process of the MEMS-based filter was presented.

An optical readout focal plane array (FPA) usually has a bent cantilever due to the micro-machining techniques. This bent morphology has a strong negative impact on optical sensitivity, which is a key factor that affects the imaging performance. In this study, an optical readout FPA with a stiffener-supported pixel is presented in order to reduce the deformation. The theoretical analysis has been developed to optimize the structure. Based on this, an FPA with a stiffener-supported pixel is fabricated. It is demonstrated that the curvature radius and optical sensitivity can increase by 5 times and 5.74 times respectively with respect to that without a stiffener. Better thermal imaging has been achieved.

This paper presents the analysis and simulation of a microelectromechanical system (MEMS) DC/DC converter based on vibration‐to‐electric energy conversion. The device transfers and accumulates the mechanical energy from ambient vibration via a variable capacitor. After the key parameters of the device are carefully discussed, the dynamics analysis is given based on the differential equation of the system. The approach provided in this paper is very helpful in designing and essentially understanding the MEMS DC/DC converter with high performance. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.