Measuring in-band distortions of mixers

This paper proposes a method to measure the in-band deterministic and stochastic contributions of nonlinear distortions in mixers. The model of the mixer as a two- or three-port device is developed. Based on this model, the measurement technique-which is a generalization of the methods developed for amplifiers-is developed. While designing the measurement method, the difficulties that arise out of the fundamental differences between mixers (three-port devices) and amplifiers (two-port devices) are taken into account. Two techniques are presented, depending on the fact that the phase of the local oscillator is known or unknown.     

Three-port binary reflective grating with high efficiency under second Bragg angle incidence

Abstract

A binary three-port reflective grating under second Bragg angle incidence is designed in this paper. Under second Bragg angle incidence, the grating can separate nearly 33% light wave energy into the 2nd order, the 1st order and the 0th diffractive orders, respectively. Rigorous coupled-wave analysis can give numerical calculation to optimize the three-port grating depths and periods. For the optimized reflective three-port grating, TE polarization and TM polarization can have different values of grating depth and period. Compared with the reported three-port binary grating under Bragg angle incidence, the diffraction efficiencies can be improved. Moreover, the modal method is applied to explain the propagating mechanism. The highly efficient three-port binary reflective grating under second Bragg angle incidence would be manufactured in the emerging industry for its novel performance.     

A calibration and measurement method of a tri-six-port networkanalyzer suitable for on-wafer characterization of three-port devices

A calibration and measurement method using a wideband tri-six-port network and analyzer (TSPNA) is proposed. The scattering parameters of a three-port device under test are found to be the unknowns of a set of nine simultaneous complex linear equations. These equations are established via a group of three calibrated linearly independent excitations. No isolators are required for calibration and measurement procedures. Three unknown reciprocal two-port standards are needed for the calibration of the TSPNA. The proposed method is rigorous, explicit, and suitable for wideband on-wafer three-port device S-parameter measurements. It can easily be adapted for heterodyne automated network analyzers equipped with three reflection test-set units     

Investigation of electrical nonlinearity of HTS thin films as applied to realization of a microwave IC mixer

The nonlinear response of superconducting thin film bridges and transmission line sections at microwave frequencies has been investigated. A number of mixer prototypes have been designed and characterized. A model, based on analysis of experimental pulsedI-V characteristics, predicting results of mixing experiments, has been introduced and good agreement with the model has been obtained.     

生产MHY-4黑火药的三料球磨机的设计及应用

用铸铝球磨机生产MHY-4黑火药,设备使用寿命长,散热性好,可以降低黑火药生产过程中的静电积累,提高黑火药生产的安全系数.     

DEM simulation for optimal design of powder mixing in a ribbon mixer

A ribbon mixer is often employed in powder mixing in a wide range of engineering fields. The structure of the ribbon mixer is extremely complicated. This structure makes it difficult to understand the mixing mechanism by experimental approaches due to problems related to accurate sampling. At present, the mixing mechanism in the ribbon mixer is empirically identified as convection, despite a lack of precise assessment. Additionally, experimental investigations to find the optimal design of the ribbon mixer have not been sufficiently conducted because of its prohibitive cost. As such, there is a lack of sufficient discussion concerning the design for better mixing in the ribbon mixer. Numerical technologies represent a promising approach for solving the aforementioned problems. Significant improvements in computer hardware have enabled numerical models such as the discrete element method (DEM) to be positively employed in powder mixing. In the current study, an identification approach is developed for convective mixing, and besides, the study explores an effective parameter for better mixing in the ribbon mixer using the DEM. A swept volume measurement approach due to paddle movement is newly developed to identify the main mixing mechanism as convection. Sensitivity analyses are performed to find an effective parameter for better mixing. Through the sensitive analyses, the blade width is indicated as an important factor for achieving better mixing. Moreover, this study shows that the relationship between the swept volume and mixing index remains, even if the paddle width changes. Thus, the swept volume measurement method is revealed as useful for identifying the mechanism as convection in the ribbon mixer. Thus, not only novel finding regarding the blade width for better mixing but also the development of an approach for identifying convective mixing in the ribbon mixer is presented herein. Incidentally, convection being the dominant mechanism is consistent with the novel finding regarding blade width achieving better mixing.     

Complex gyrator circuit of a three-port circulator using a planar resonator composed of a gyromagnetic disk, a triplet of UEs and a triplet of single radial magnetic walls

A classic planar gyromagnetic resonator, encountered in the construction of three-port circulators, is one with top and bottom electric walls and a magnetic sidewall symmetrically loaded with a triplet of single magnetic walls. The main purpose is to experimentally characterise the complex gyrator circuit of a three-port junction using a resonator made up of a circular region, a triplet of single magnetic walls and a triplet of short 58 long UEs. It is compatible with the design of degree-2 circulators with commercial specifications and one experimental example is included for completeness sake. The effect of the UE embodied in the resonator under consideration is to decouple the coupling angle of the resonator terminals from any external microwave circuits, thereby facilitating the practical design of degree-2 circulators. A similar magnetised resonator loaded with a triplet of triple magnetic walls instead of single ones is also dealt with. It has the effect of reducing the spacing between the first three cut-off numbers of the isotropic geometry.     

Optimization of a microfluidic mixer for studying protein folding kinetics

We have applied an optimization method in conjunction with numerical simulations to minimize the mixing time of a microfluidic mixer developed for protein folding studies. The optimization method uses a semideterministic algorithm to find the global minimum of the mixing time by varying the mixer geometry and flow conditions. We describe the minimization problem and constraints and give a brief overview of the optimization algorithm. We present results of the optimization, including the optimized geometry and parameter sensitivities, and we demonstrate the improvement in mixing performance with experiments using microfabricated mixers. The dye-quenching experiments of the original and optimized mixer designs show respective mixing times of 7 and 4 mus, a 40% reduction. The new design also provides more uniform mixing across streamlines that enter the mixer. The optimized mixer is the fastest reported continuous flow mixer for protein folding.     

Statistical comparison of high-shear versus low-shear granulation using a common formulation

Experimental combinations from the ranges assigned to the independent factors were studied using both a low-shear (planetary) mixer and a high-shear mixer for granulation. The independent factors studied were X₁ calcium phosphate/mannitol ratio, X₂ pregelatinized starch, X₃ magnesium stearate, X₄ mixer type, and X₅ compression pressure. To optimize the tablet properties fully, the experimental range was varied from -2 to +2 experimental units, with the exception of X₄, which was assigned -1 for the planetary mixer and +1 for the high-shear mixer. Drug dissolution did not seem to be affected by mixer type, but tablet hardness was affected by mixer type.     

薄壁钢筋混凝土烟囱和水塔定向爆破拆除

结合某薄壁钢筋混凝土烟囱和水塔的定向爆破拆除,提出了确保定向爆破安全、成功的几条重要技术措施:①爆破切口圆心角可减小到208°;②在后支撑中心点加钢斜腿支撑,既增大了抵抗烟囱的下坐支撑力,又克服了烟囱的后坐力;③采用“<”形锐角定向窗切口,使定向窗端部受力更均匀;④首次试用快干水泥堵塞炮孔,有效防止了浅眼爆破的冲炮;⑤采用砂包墙埂作飞石防护屏障,既彻底阻挡了飞石,又屏蔽了爆破声响。最终爆破效果相当完美。     

The joint mixing action of the static pre-mixer and the rotating drum mixer – Discrete element method approach

In this study, the mixing performance of coupled mixing action of the Komax static mixer (which is used as a pre-mixer) and rotating drum (applied as the final mixer) was explored in the maize meal mixing operation. The main objective of this paper was to predict the behaviour of the previously grinded maize particles, during the mixing process in static mixer and drum mixer, and to explore the possibilities to shorten the mixing time in the main mixer (in order to reduce the energy consumption).Three different experiments were performed: in the first experiment, possibilities of static mixer were explored, second experiment showed the mixing performance of rotating drum, and the combination of these two mixing devices was investigated in the third experiment. Homogeneity of the obtained mixtures was determined experimentally, by the “Microtracers” method.The Discrete Element Method was used for modelling of granular flow in the pre-mixing and final mixing applications, and to predict the inter-particle mixing quality within a static mixer and the rotating drum mixer. The results of the numerical simulation are compared with appropriate experimental results. The possible industrial application of this model could be the optimization of parameters of mixing systems taking into account the quality and the duration of the mixing process.     

混合机配料自动控制系统设计

介绍了一个混合机配料自动控制系统,上位机采用PC机,下位机采用西门子SIMATICS7-200的可编程控制器,描述了系统的硬件组成、软件设计和上下位机实现点对点的通讯方法.在实际生产中,该自动控制系统可以提高配料精度、产品质量和劳动生产率,可以消除误操作、实现混合机的升级换代.     

Comparison of 24 GHz receiver front-ends using active and passive mixers in CMOS

This study compares the key parameters of two integrated receiver front-end architectures: low noise amplifier (LNA) with active mixer against LNA with passive mixer. The authors discuss the differences in the performance and their impact on system characteristics for radar applications. A low-IF down-conversion receiver implementation is considered. The results are compared in measurement for two 24 GHz receiver front-end chips realised in a 0.13 mm digital CMOS process. Both circuits have been characterised over automotive temperature range -40 to 125°C. The front-end with an active mixer offers lower LO power dependence and exhibits better temperature stability, whereas the front-end with a passive mixer has the advantage of better input-referred linearity and lower flicker noise.     

Design of low-cost 183 GHz subharmonic mixers for commercial applications

Techniques are presented for designing fixed-tuned millimetre-wave components with the least number of parts to minimise the cost and maximise the potential for volume manufacture. Design techniques for millimeter-wave mixer components targeted at potentially high volume applications, such as medical and security screening and nondestructive testing, require certain compromises in the use of CAD tools. The compromise techniques are demonstrated using commercially available foundry diodes in the design of a 183 GHz subharmonic mixer for earth observation applications. The resulting mixer exhibits 6.85 dB double sideband conversion loss and a mixer temperature of 988 K using 5 mW of local oscillator power at 92 GHz     

电站除灰用加湿搅拌机的综合比较

目前电站电厂等对煤灰处理方法其中之一是采用了加湿搅拌机的形式.加湿搅拌机是对煤灰进行加水搅拌再通过车辆或船舶运输出去,这样可以有效的避免扬尘,保护环境,成本相对较低.目前在使用的加湿搅拌机的样式有三种,本文通过综合比较,提出最适合的加湿搅拌机的形式,供输灰系统的改造和设计参考.     

Development of Agglomerated Talc II: Optimization of the Processing Parameters for the Preparation of Granulated Talc

Agglomerated talc was prepared by the wet granulation method using a planetary mixer and a high speed mixer. The effect of the amount of water added and granulation time for the planetary mixer on the physical properties of the agglomerated talc were investigated by a response surface design. The speed of the agitator and granulation time for the high speed mixer were selected as the two independent variables to study the granulation processing using the same statistical design. Several characteristics of the product prepared by a planetary mixer or high speed mixer were well expressed as a quadratic function of the two independent variables studied in coded level. By superimposing contour plots of granule friability and percent fine of granule, a region was obtained where the requirements of friability and percent fines could be satisfied by controlling the processing variables. The optimal granulation condition was chosen from that region. The values of the measured responses of the agglomerated talc produced using the optimal granulation condition agreed well with the predicted values obtained from the regression equations.     

Electrospray micromixer chip for on-line derivatization and kinetic studies

An electrospray microchip for mass spectrometry comprising an integrated passive mixer to carry out on-chip chemical derivatizations is described. The microchip fabricated using UV-photoablation is composed of two microchannels linked together by a liquid junction. Downstream of this liquid junction, a mixing unit made of parallel oblique grooves is integrated to the microchannel in order to create flow perturbations. Several mixer designs are evaluated. The mixer efficiency is investigated both by fluorescence study and mass spectrometric monitoring of the tagging reaction of cysteinyl peptides with 1,4-benzoquinone. The comparisons with a microchip without a mixing unit and a kinetic model are used to assess the efficiency of the mixer showing tagging kinetics close to that of bulk reactions in an ideally mixed reactor. As an ultimate application, the electrospray micromixer is implemented in a LC-MS workflow. On-line derivatization of albumin tryptic peptides after a reversed-phase separation and counting of their cysteines drastically enhance the protein identification.     

Numerical analysis of similarities of particle behavior in high shear mixer granulators with different vessel sizes

This paper deals with the numerical analysis of kinematic and dynamic similarities of particle behavior in high shear mixer granulators with different vessel sizes. The three-dimensional particle motion in high shear mixer granulators with four different vessel sizes was calculated using a discrete element method (DEM). The geometrically similar mixer granulators equipped with a flat-shaped impeller blade were used as simulated mixer granulators.Kinematic and dynamic similarities of particle behavior in various vessel sizes under a constant normalized agitation power were numerically analyzed. In various vessel sizes, dynamic similarity expressed by the particle collision energy was confirmed under a constant normalized agitation power, while kinematic similarity expressed by the particle velocity was not confirmed. These results indicate that the dynamic similarity should be maintained for successful scale-up of high shear mixer granulators.     

Optimum absorbed heterodyne power for superconducting NbN hot-electron bolometer mixer

Absorbed heterodyne power has been measured in a low-noise broadband hot-electron bolometer (HEB) mixer for the terahertz range, operating on the effect of electron heating in the resistive state of an ultrathin superconducting NbN film. It is established that the optimum absorbed heterodyne power for the HEB mixer operating at 2.5 THz is about 100 nW.