带约束的复FIR数字滤波器Chebyshev设计算法

本文主要讨论了复FIR数字滤波器的频域不等式约束Chebyshev设计问题.作者首先把文献[1]中的复交错点组定理扩展到有不等式约束的情况,之后根据扩展定理中对最优解特性的描述,并结合复Remez算法[1]及赖晓平的迭代Remez算法[2][3],提出了一种有效的算法来解决频域带不等式约束的复FIR数字滤波器的Chebyshev设计问题.如果问题的解存在,则算法能保证收敛到最优解.作者用MATLAB语言对上述算法进行了实现并做了仿真分析.     

A 1-V 86-mW-RX 53-mW-TX Single-Chip CMOS Transceiver for WLAN IEEE 802.11a

A 1-V WLAN IEEE 802.11a CMOS transceiver integrates all building blocks on a single chip including a transformer-feedback VCO and a stacked divider for the frequency synthesizer and 8-bit IQ ADCs and 8-bit IQ DACs. Fabricated in a 0.18-mum CMOS process and operated at a single 1-V supply, the receiver and the transmitter consume 85.7 mW and 53.2 mW, including the frequency synthesizer, respectively. The total chip area with pads is 12.5 mm².     

Encapsulation of quantum dots and carbon nanotubes with polypyrrole in a syringe needle for automated molecularly imprinted solid phase pre-concentration of ochratoxin A in red wine analysis

Nanometer-sized semiconductor quantum dots (QDs with CdSe core and ZnS shell) and carbon nanotubes (CNTs with multi-walls) were encapsulated inside a stainless steel syringe needle by electrodeposition of polypyrrole (PPy). By cross-linking the PPy with ethylene glycol dimethacrylate (EGDMA) in the presence of ochratoxin A (OTA) as a template, molecularly imprinted polypyrrole (MIPPy) was formed on the nano-hybrid structure at an increased specific surface area. The MIPPy/CNTs/QDs-modified needle was readily adapted in an autosampler for micro-solid phase preconcentration (μSPP) of OTA from a red wine sample. After pulsed elution (PE) with 2% triethylamine (TEA), the OTA was determined by high performance liquid chromatography (HPLC) with fluorescence detection (FD). In comparison with MIPPy/CNTs, this new nano-hybrid structure of MIPPy/CNTs/QDs significantly improved the % recovery of OTA. The method, MIPPy/CNTs/QDs-μSPP-HPLC-FD, demonstrated that the MIPPy was truly a molecularly imprinted polymer (MIP) with specific recognition for OTA. All red wine matrix components could be differentially washed out, prior to accurate determination of the strongly bound OTA.     

A Coaxial Bragg Reflector for Cyclotron Autoresonance Maser Oscillators

A coaxial Bragg reflector is suggested for the application in the cyclotron autoresonance masers (CARMs), where both the outer wall and inner rod are corrugated with weak axisymmetric-sinusoidal-ripple, and a concept design is presented. It is found that, compared to the cylindrical Bragg reflector, the coaxial Bragg reflector has larger dimensional size, narrower bandwidth, and larger eigenvalue intervals. These peculiarities are favorable to the mode selectivity, the ability of dissipating the ohmic heat on the wall, the oscillating startup of the operating mode, and machining manufacture, and therefore, this new kind of Bragg reflector can be developed into a coaxial resonator for the high-power CARMs     

HOESCH型压滤机在赵庄选煤厂的应用

在赵庄矿选煤厂处理的原煤中，13—0mm粒级末煤含量高（67．23％）、0．5～0mm粒级的原生煤泥含量大（11．79％）。为提高煤泥水系统的处理能力，设计中选用了德国OUTOKUMPU公司生产的HOESCH 40S-1516／19V M50PP／PP型压滤机来处理细煤泥。本文介绍了该设备的主要技术特征、特点和实际应用的效果。     

Stability analysis of chatter vibration for a thin-wall cylindrical workpiece

The vibration characteristics and the vibration direction angle between the beam mode and shell mode of the three-jaw clamped thin-wall cylindrical workpiece will change according to the relative position of the cutting tool to the chucking jaws. This will induce parametric vibration and cause the chatter characteristics of a thin-wall cylindrical workpiece to become more complicated than those of a solid workpiece. In this study, the three-jaw clamped thin-wall cylindrical workpiece was considered as a parametrically excited vibration system. Initially, the relationship between the parametric vibration and the workpiece system structure was investigated, and then the equivalent stability cutting depth of the thin-wall cylindrical workpiece was analyzed by a numerical calculation method. When the three-jaw clamped thin-wall cylindrical workpiece was considered as a parametric vibration system, the analytical results were consistent with the experimental results.     

Early results of AV sequential pacing on left ventricular outflow obstruction after Senning procedure

Dual chamber pacing was shown to decrease left ventricular outflow tract (LVOT) obstruction in patients with hypertrophic cardiomyopathy 30 years ago. We report early results of AV sequential pacing from the LV apex in a patient with transposition of the great arteries who is post-Senning procedure. LVOT obstruction resulted from septal deviation and systolic anterior motion of the mitral valve. Pacing was indicated for sinus node dysfunction. AV sequential pacing with a short optimal AV interval of 60 ms demonstrated a 45% reduction in the degree of LVOT obstruction. This article suggests that LVOT obstruction after the Senning procedure can be palliated by asynchronous septal contraction induced by AV sequential pacing, even if the activation is from LV apex, and avoid or postpone surgery in selected situations.     

AGN 191976: a novel thromboxane A2-mimetic with ocular hypotensive properties

The possible subdivision of thromboxane A2-sensitive (TP) receptors is currently a controversial subject. We report herein on a novel thromboxane A2 mimetic, AGN 191976, which has almost identical pharmacological activity to the well-characterized prostaglandin H2/thromboxane A2 (PGH2/TxA2) mimetic U-46619, but its effects on intraocular pressure are quite distinct from U-46619. Prostanoid receptor activity was determined in vitro using different smooth muscle assays and platelets. Intraocular pressure was measured tonometrically in ocular normotensive Beagle dogs and Cynomolgus monkeys. Conjunctival microvascular permeability was determined in guinea pigs. Despite closely resembling U-46619 as a potent and selective TP receptor agonist, AGN 191976 was a potent ocular hypotensive in dogs and monkeys whereas U-46619 did not lower IOP in either species. The ocular hypotensive effect of AGN 191976 in dogs was attenuated by pretreatment with the TP receptor antagonist SQ 29548. Thus, the ocular hypotensive effects of AGN 191976 are consistent with TP receptor stimulation. Both TxA2-mimetics caused plasma leakage in the guinea pig conjunctiva. The disparate activities of U-46619 and AGN 191976 in our studies suggest the existence of heterogeneous populations of TP-receptors in the eye.     

Detection of dimension sets in engineering drawings

This correspondence presents a system for detecting dimension sets in engineering drawings that are drawn to ANSI drafting standards. A new rule-based text/graphics separation algorithm and a model-based procedure for detecting arrowheads in any orientation have been developed. Arrowhead tracking and search methods are used to extract leaders, tails, and witness lines from segmented images containing only graphics. Text blocks and feature control frames extracted from the segmented images are than associated with their corresponding leaders to obtain complete dimension sets. Experimental results are presented     

Thermo-oxidative degradation of poly(ethylene glycol)/poly( -lactic acid) blends

The thermo-oxidative degradation of poly(ethylene glycol)/poly( -lactic acid) (PEG/PLLA) blends was studied by infra-red spectroscopy (IR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and thermogravimetry (TGA). The thermo-oxidative degradation of PEG occurred after a period time of aging in air at 80 °C. The mechanism of thermo-oxidative degradation of PEG was found to be the random chain scission of the main chain. As PEG blending with PLLA, the existence of PLLA appeared to enhance the thermo-oxidative degradation of PEG. The enhancement of thermo-oxidative degradation increased first and then decreased with the increase of PLLA. The results could be attributed to the ease of abstraction of the carboxylic hydrogen (–COOH) of PLLA, which enhanced the thermo-oxidative degradation of PEG. Also, the dilution effect of PLLA on the concentration of free radicals was an important factor of the thermo-oxidative degradation.