新型低功耗电磁流量计设计

提出了一种MSP430单片机的低功耗电磁流量计设计方案,设计了低功耗的模拟信号处理放大电路和励磁电路.软件上采用间歇励磁工作的方法,动态调整采样间隔时间,降低了系统的功耗.试验表明,在休眠时,系统电流小于15μA;工作时,系统电流小于20mA.系统精度可达1%.     

A new universal sorbent for hazardous spills

In this paper, the authors present information on the properties of a new, broad spectrum sorbent; a product that has the potential to render spilled liquids easily and safely collected and removed. Data on the chemical, physical, and toxicological properties are given. Methods for measuring sorption index and suppression of vapor emission are described. The sorbtion ratio of more than 70 hazardous liquids are listed. The vapor emission suppression for several volatile materials is given. A unique packaging system which makes the product convenient for field use is described.     

MEDUSA-32: A low noise, low power silicon strip detector front-end electronics, for space applications

In this report we describe a mixed analog-digital integrated circuit (IC) designed as the front-end electronics for silicon strip-detectors for space applications. In space power consumption, compactness and robustness become critical constraints for a pre-amplifier design. The IC is a prototype with 32 complete channels, and it is intended for a large area particle tracker of a new generation of gamma ray telescopes. Each channel contains a charge sensitive amplifier, a pulse shaper, a discriminator and two digital buffers. The reference trip point of the discriminator is adjustable. This chip also has a custom PMOSFET transistor per channel, included in order to provide the high dynamic resistance needed to reverse-bias the strip diode.

The digital part of the chip is used to store and serially shift out the state of the channels. There is also a storage buffer that allows the disabling of non-functioning channels if it is required by the data acquisition system.

An input capacitance of 30 pF introduced at the input of the front-end produces less than 1000 electrons of RMS equivalent noise charge (ENC), for a total power dissipation of only 60 μW per channel.

The chip was made using Orbit's 1.2 μm double poly, double metal n-well low noise CMOS process. The dimensions of the IC are 2400 μm × 8840 μm.     

A universal throw model and its applications

A deterministic model has been developed that describes the throw of debris or fragments from a source with an arbitrary geometry and for arbitrary initial conditions. The initial conditions are defined by the distributions of mass, launch velocity and launch direction. The item density in an exposed area, i.e. the number of impacting debris or fragments per unit of area, has been expressed analytically in terms of these initial conditions. While existing models make use of the Monte Carlo technique, the present model uses the source function theorem, an underlying mathematical relation between the debris density and the initial distributions. This gives fundamental insight in the phenomenon of throw, and dramatically reduces the required number of trajectory calculations.     

A low power magnetometer for vehicle detection

A miniature, low power two-axis Brown type ring. core magnetometer is described which can be used for motor vehicle detection. For relatively little power (<1mw), the sensor functions over a large dynamic range (pm.8times10^{-4}Tesla) with a sensitivity of 7μv/nT (both orthogonal axes) and a self noise at zero field less than 3nTp_p(.03 to 3 Hz). A low power digital feedback loop has been developed to null the magnetometer signal and compensate for temperature induced offset variations. The sensor is also suitable for a stationary short baseline gradiometer.     

面向多处理器SoC设计的低功耗软硬件划分

提出了解决多处理器SoC的低功耗软硬件划分问题的方法--基于神经网络的禁忌搜索算法.其基本思想是:真实的生物神经元具有抑制重复激活的阻尼特性,这与禁忌搜索对重复搜索加以限制相类似,因此设计具有阻尼特性的神经网络实现禁忌搜索算法,受阻尼特性抑制的神经元对应禁忌活动.由于神经网络复杂的动态特性和禁忌搜索优秀的全局搜索能力,该算法能够有效地跳出局部最优解.对真实任务图的实验表明,与遗传算法相比,该算法不但具有搜索速度上的优势,而且所得到的绝大部分软硬件划分方案有更低的系统功耗.     

Ni-Mn hydroxides as new high power electrode materials for supercapacitor applications

The coprecipitation of Ni and Mn hydroxides followed by freeze drying results in the formation of agglomerated 20-30 nm particles of complex hydroxide with spinel-like structure. The thermal decomposition of this hydroxide causes the formation of ilmenite-type complex oxide at T > 300 °C without considerable changes in the Ni and Mn valence states according to X-ray photoelectron spectroscopy data. Further processing at T ≤ 400 °C is accompanied by significant particle intergrowth though their internal structure remains nanostructured. Ni-Mn oxide- and hydroxide-based electrodes revealed a significant reversible electrochemical activity in the alkaline electrolytes and an extended operating voltage window (~ 1.8 V). Ni-Mn ilmenite-based electrode materials demonstrated a low fade rate and high specific electrochemical capacity values at high discharge rates (up to 70 mAh g^− 1 at I = 70 mA cm^− 2) that makes feasible their application in high rate batteries and electrochemical supercapacitors.     

Wettability control of ZnO nanoparticles for universal applications

Herein, a facile approach for the fabrication of a superhydrophobic nanocoating through a simple spin-coating and chemical modification is demonstrated. The resulting coated surface displayed a static water contact angle of 158° and contact angle hysteresis of 1°, showing excellent superhydrophobicity. The surface wettability could be modulated by the number of ZnO nanoparticle coating cycles, which in turn affected surface roughness. Because of its surface-independent characteristics, this method could be applicable to a wide range of substrates including metals, semiconductors, papers, cotton fabrics, and even flexible polymer substrates. This superhydrophobic surface showed high stability in thermal and dynamic conditions, which are essential elements for practical applications. Furthermore, the reversible switching of wetting behaviors from the superhydrophilic state to the superhydrophobic state was demonstrated using repeated chemical modification/heat treatment cycles of the coating films.     

High power universal piezoelectric transformer

This study describes a multilayer piezoelectric voltage and power transformer that has one direction poling, operates in a wide-frequency range and delivers both step-up and step-down voltages by inverting the electrical connections. In this design, the input and output electrodes are on the same side of the disk and are isolated from each other by a fixed isolation gap. The electrode pattern is a ring/dot structure such that it uses radial mode for both input and output part that are built-in on the same ceramic disk. A prototype transformer was fabricated of size 15 x 2.78 mm2 having mass of 3.8 gm. In the step-down configuration at the constant output power of 6 W, the transformer characteristics across a 100 omega load were found to be efficiency = 92%, gain = 0.21 input voltage = 110 V(rms), and temperature rise = 20 degrees C from the room temperature. In the step-up configuration at the constant output power of 5 W, the transformer characteristics across a 5 komega load were found to be efficiency = 97%, gain = 9.5, input voltage = 16 V(rms), and temperature rise = 8 degrees C from the room temperature. A detailed equivalent circuit analysis of the transformer was done, and the results were found to be in excellent agreement with the experimental results.     

一种通用移动支付模型及其协议的研究

以SEMOPS模型为基础,提出了一种新的通用移动支付模型及其协议.该模型与协议具有应用无关性.通过对交易数据的变换处理和为该模型设计的专有协议,使得用户的交易数据等敏感信息对于支付系统是透明的.另外,由于引入可信的第三方实体,降低了对银行等传统可信实体的信任依赖程度,因此提高了系统的安全性.利用形式化的方法验证了所设计的移动支付协议可以保证支付过程的不可抵赖性.     

Simple and universal platform for logic gate operations based on molecular beacon probes

A new platform technology is herein described with which to construct molecular logic gates by employing the hairpin-structured molecular beacon probe as a basic work unit. In this logic gate operation system, single-stranded DNA is used as the input to induce a conformational change in a molecular beacon probe through a sequence-specific interaction. The fluorescent signal resulting from the opening of the molecular beacon probe is then used as the output readout. Importantly, because the logic gates are based on DNA, thus permitting input/output homogeneity to be preserved, their wiring into multi-level circuits can be achieved by combining separately operated logic gates or by designing the DNA output of one gate as the input to the other. With this novel strategy, a complete set of two-input logic gates is successfully constructed at the molecular level, including OR, AND, XOR, INHIBIT, NOR, NAND, XNOR, and IMPLICATION. The logic gates developed herein can be reversibly operated to perform the set-reset function by applying an additional input or a removal strand. Together, these results introduce a new platform technology for logic gate operation that enables the higher-order circuits required for complex communication between various computational elements.     

A new fabrication method of low stress PECVD SiNx layers for biomedical applications

A new fabrication method to produce low residual stress PECVD SiN_x layers at high deposition rates was developed and their biomedical applications were reported in this paper. This new method employed up to 600 W high power to fabricate low stress SiN_x layers in high frequency (13.56 MHz). By adjusting the composition of reactant gases, the residual stress can be lowered to 4 MPa and high deposition rate up to 320 nm/min can be achieved. In addition, this paper also investigated the influence of other important parameter, such as pressure, power and gases flow rates. Moreover, by using this optimized process, an 11 μm thick low stress SiN_x layer was produced, which will be used to fabricate large window area for cell culture. Finally, a successful cell culture test involving cultivating mouse stem cells onto the porous membrane made of these low stress PECVD SiN_x layers indicated that these layers are biocompatible and are suitable for biomedical applications.     

A new undulator scheme providing various polarization states with low on-axis power density

A new undulator scheme is proposed to enable flexible utilization of polarization properties of synchrotron radiation, which is based on the composite-period undulator originally proposed to improve the wavelength tunability of free electron lasers. It has an advantage over the conventional undulators that the on-axis power density is kept low even when a high K value is applied to lower the photon energy. The basic principle and availability of various polarization states are presented together with a practical example.     

A new power standard for audio-frequency measurements

A thermal power comparator for audio-frequency measurements is presented. It is essentially a double-bridge-type multiplier that consists of two multijunction thermal converters that contain two heaters. Together with a precision inductive voltage divider and current transformer for extending the voltage and current range, the comparator ensured a high-precision power standard with an AC/DC transfer error of less than 15 p.p.m. in the audio-frequency range     

A new microwave dielectric ceramic for LTCC applications

A new low-sintering temperature microwave dielectric ceramic was found and investigated in the Li₂O–Nb₂O₅–TiO₂ (Li₂O:Nb₂O₅:TiO₂ = 5.7:1:14.7, by mole, abbreviated as LNT) system. This new microwave dielectric ceramic shows a relatively high permittivity (47), high Q × f values up to 17,800 GHz, and low temperature coefficients (57 ppm/°C), which were obtained via sintering at 1,125 °C. With the low-level doping of B₂O₃–CuO (BCu) (below 2 wt%), the sintering temperature of the LNT ceramic could be effectively reduced to 900 °C. The addition of BCu does not induce apparent degradation in the microwave properties but lowers the τ _f value. Typically, the 2.0 wt% BCu-doped ceramics sintered at 900 °C have better microwave dielectric properties of ε_r = 48.7, Q × f = 16,350 GHz, τ _f  = 32 ppm/°C, which suggest that the ceramics could be applied in multilayer microwave devices requiring low sintering temperatures.     

High power universal piezoelectric transformer.

This study describes a multilayer piezoelectric voltage and power transformer that has one direction poling, operates in a wide-frequency range and delivers both step-up and step-down voltages by inverting the electrical connections. In this design, the input and output electrodes are on the same side of the disk and are isolated from each other by a fixed isolation gap. The electrode pattern is a ring/dot structure such that it uses radial mode for both input and output part that are built-in on the same ceramic disk. A prototype transformer was fabricated of size 15 x 2.78 mm2 having mass of 3.8 gm. In the step-down configuration at the constant output power of 6 W, the transformer characteristics across a 100 ohms load were found to be efficiency = 92%, gain = 0.21 input voltage = 110 Vrms, and temperature rise = 20 degrees C from the room temperature. In the step-up configuration at the constant output power of 5 W, the transformer characteristics across a 5 kohms load were found to be efficiency = 97%, gain = 9.5, input voltage = 16 Vrms, and temperature rise = 8 degrees C from the room temperature. A detailed equivalent circuit analysis of the transformer was done, and the results were found to be in excellent agreement with the experimental results.     

Growth and characterization of titanium silicate nanofilms for gate oxide applications

Atomic layer chemical vapor deposition (ALCVD) of titanium silicate nanofilms using a precursor combination of tetrakis-diethylamido-titanium (Ti(N(C2H5)2)4) and tetra-n-butyl-orthosilicate (Si(O(n)Bu)4) was studied for high dielectric gate oxides. ALCVD temperature window in our study was 170-210 degrees C with a growth rate of 0.8 A/cycle. We investigated the effects of deposition conditions, such as deposition temperature, pulse time of precursor and purge injection, on the titanium silicate nanofilm growth. The saturated composition of Ti/(Ti+ Si) ratio was 0.6 and impurity concentrations were less than 1 atomic %. Dielectric constant (k) of the as-deposited titanium silicate film was approximately 10.5. Hysteresis in capacitance-voltage (C-V) measurements was less than 0.35 V before and after annealing. The leakage current density of the as-deposited and 400 degrees C annealed film was 1.4 x 10(-4) A/cm2, 4.2 x 10(-4) A/cm2, respectively, at a bias of -1 V.