A simple and effective design method for multiband filtering power divider

This letter presents a simple and effective design method for multiband filtering power divider (FPD) in wireless communication systems. By elaborately coupling multiple pairs of stub‐loaded resonators (SLRs) with input/output feedlines, a flexible topology for multiband FPD is built. Not only can each pair of the SLRs generate one passband, but also control the respective center frequency and bandwidth independently. Meanwhile, isolation resistors are arranged between each pair of the SLRs to independently adjust each band isolation, finally achieving nice isolation over a wide frequency band. To validate the design concept, a prototype triple‐band FPD working at 1.30, 1.62, and 2.22 GHz is devised, simulated, and tested. Measurements have good agreement with simulations, indicating that the FPD has the advantages of its independently controllable frequency and bandwidth, high passband selectivity, and good isolation over a broadband frequency band.     

A novel method for determining machine subgroups and backups with an empirical study for semiconductor manufacturing

Wafer fabrication for semiconductor manufacturing consists of multiple layers, in which the displacements (i.e., overlay errors) between layers should be reduced to enhance the yield. Although it can reduce variance between layers by fixing the exposure machine (i.e. steeper or scanner), it is not practical to expose the wafer on the same machine from layer to layer for the lengthy fabrication process in real setting. Thus, there is a critical need to determine the similarity machine subgroups, in which appreciate backups for unexpected machine down can be also prioritized. This study aims to develop a novel methodology to fill this gap based on the proposed similarity measurement of systematic overlay errors and residuals. The proposed methodology was validated via empirical study in a wafer fab and the results showed practical viability of this approach. Received: May 2005 / Accepted: December 2005     

基于表观BRDF的泡沫金属辐射特性反演测量方法

泡沫金属是通过在金属基体上形成大量孔隙结构而得到的一类新型多功能材料,在太阳能利用、强化换热等领域有重要应用价值,其辐射特性参数是分析其内部辐射传递的必要物性数据。提出一种基于表观双向反射分布函数（ BRDF）测量数据反演泡沫金属热辐射物性的方法,利用测量的多角度入射的表观BRDF数据结合辐射传递方程求解来反演泡沫金属的等效辐射特性。对泡沫铁镍（50 ppi ）、泡沫铜（90 ppi）及泡沫镍（30 ppi）三种泡沫金属样品在波长660 nm激光照射下1/2半球空间的表观BRDF分布进行了实验测量,并对其辐射特性进行了反演,首次获得了这三种材料的辐射特性参数,其辐射物性表现出明显的半透明性质,散射反照率随着孔隙数密度的增加而增加,散射相函数呈后向散射占优。     

Test of a ground-based microwave radiometer for atmospheric temperature profiling with meteorological applications

The performance of a ground-based microwave radiometer of new design to be used for remote sensing of the temperature profile of the atmosphere has been tested. It is continuously tunable in the range 52-8-58-8 GHz and has a high absolute accuracy. The radiometer measurements have been analysed with the statistical inversion method and the retrieved profiles have been compared with 28 simultaneous radiosoundings. The r.m.s. difference under clear-sky and cloudy conditions was, on these occasions, less than l-5degK up to 6km and 4km, respectively, less than OdegK up to 8 and 5-5 km, respectively, and less than 3-0degK up to 9 and 7-5 km, respectively. Methods to increase the profiling accuracy are discussed.     

A novel rectifying circuit for microwave power harvesting system

Many researchers continue to look for novel means to harvest energy and generate power using existing sources thus eradicating the need of batteries and power supplies which only add up to the cost of the system. A rectifier is the main component in energy harvesting circuits as it converts RF energy from available sources to DC power. This article aimed at developing a novel rectifying circuit to be used in harvesting applications at a frequency of 900 MHz. Besides, it is also aimed to enhance the output voltage of Cockcroft Walton rectifier circuit and Dickson rectifier. The design is built by integrating the Cockcroft Walton rectifier, arranged in series, with the Dickson rectifier, arranged in parallel. A Schottky diode HSMS 285C is selected for designing the rectifiers circuit. A simulation of the circuit was optimized utilizing ADS 2009. The rectifiers had been fabricated on an RT/Duroid 5880 (RO5880) printed circuit board (PCB) substrate with a dielectric constant and loss tangent of 2.2 and 0.0009, respectively. Simulation and experimental results show great output thresholds for the three models. The novel rectifier had the highest efficiency and output voltage.     

A novel method for determining the key customer requirements and innovation goals in customer collaborative product innovation

Customer collaborative production innovation (CCPI) has become a worldwide new product design trend. The essential step to implement CCPI is to clear customer requirements and innovation goals for products. Based on the integration of traditional competitive priority ratings of customer requirements method for quality function deployment and grey relational analysis, this paper proposes a novel hybrid competitive priority ratings of customer requirements method for CCPI to identify the key customer requirements and innovation goals for a product. The method takes the heterogeneity of customers into consideration and allows different types of customers to assess customer requirements in their preferred or familiar formats which reflect their uncertainty degree. The proposed hybrid competitive priority ratings of customer requirements method represents a general approach for CCPI, does not require any transformation of multiform customers’ assessments that would cause information loss or information distortion. Its potential applications in determining the key customer requirements and innovation goals for CCPI are illustrated with a case study of smart phone development.     

A novel experimental setup for gas microflows

A new experimental setup for flow rate measurement of gases through microsystems is presented. Its principle is based on two complementary techniques, called droplet tracking method and constant-volume method. Experimental data on helium and argon isothermal flows through rectangular microchannels are presented and compared with computational results based on a continuum model with second-order boundary conditions and on the linearized kinetic BGK equation. A very good agreement is found between theory and experiment for both gases, assuming purely diffuse accommodation at the walls. Also, some experimental data for a binary mixture of monatomic gases are presented and compared with kinetic theory based on the McCormack model.     

A method for stability analysis of small-signal microwave amplifiers

This paper presents a method for analyzing the stability of small-signal microwave amplifiers with any topology. This analysis is performed using the Nyquist criterion and allows detection of the so-called odd-mode instabilities. The method is easily applicable by using commercially available microwave CAD. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 293–302, 1998.     

A novel neural Smith chart for use in microwave circuitry

In this article, briefly the Smith chart is mapped with an artificial neural network (ANN) covering its whole details to be exploited CAD of the microwave circuitry. Thus, relative to the similar works in the existing literature, this article provides the continuous Smith chart domain to facilitate the “Smith chart” methodology in solving the highly nonlinear transformation equations between the rectangular impedance and polar reflection planes for an infinite number of passive impedance to be used in design tasks of the microwave circuits. Data ensembles for the training and testing processes are obtained from the systematically selected locations on the Smith chart with the adaptive radius sampling algorithm. The ANN architecture is also simple, which consists of the two simple multilayer perceptron (MLP) modules with the common inputs which are the termination Z_S = R_S + jX_S, line {?, Z₀} operation bandwidth B between the defined f_min, f_max and the dielectric ε. Briefly, the outputs of these ANN modules are the standing waves and the impedance transformation, which are the characteristic features of the transmission line circuits. Activation of the hidden layers of the modules are performed by the tangential‐sigmoid type of function while the output layers are activated linearly. Furthermore, the neural unit element (NUE) is defined by the two independent neural networks as problems in the forward and reverse directions to be incorporated into the analysis and design algorithms of the unit element (UE). This can also be considered as solving the simultaneous nonlinear equation set for (?, Z₀) parameters of the required impedance transformations Z_OUT(ω) = R_OUT (ω) + X_OUT (ω) from the given complex termination Z_S = R_S + jX_S. Applications of the Neural Smith chart are given by the numerous examples with the proved accuracy. Thus it has been verified that this neural Smith chart can be exploited for the whole classical transmission line theory including impedance matching. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

A novel kernel method for clustering

Kernel methods are algorithms that, by replacing the inner product with an appropriate positive definite function, implicitly perform a nonlinear mapping of the input data into a high-dimensional feature space. In this paper, we present a kernel method for clustering inspired by the classical k-means algorithm in which each cluster is iteratively refined using a one-class support vector machine. Our method, which can be easily implemented, compares favorably with respect to popular clustering algorithms, like k-means, neural gas, and self-organizing maps, on a synthetic data set and three UCI real data benchmarks (IRIS data, Wisconsin breast cancer database, Spam database).     

A generalized analysis method for microwave circuits with diodes

A generalized analysis method for nonlinear circuits composed of multiple devices, multi-frequency excitation, and a multiport linear embedding subnetwork is proposed. An adaptable computing program is developed. The method is demonstrated by application to a microwave balanced mixer. The effect of parameter difference between two diodes on the behavior of a mixer is investigated.     

A novel method for dictionary translation

The paper addresses the problem of automatic dictionary translation.The proposed method translates a dictionary by means of mining repositories in the source and target languages, without any directly given relationships connecting the two languages. It consists of two stages: (1) translation by lexical similarity, where words are compared graphically, and (2) translation by semantic similarity, where contexts are compared. In the experiments Polish and English version of Wikipedia were used as text corpora. The method and its phases are thoroughly analyzed. The results allow implementing this method in human-in-the-middle systems.     

A comparative study of microwave radiometer observations over snowfields with radiative transfer model calculations

The increasing demand for water throughout the world imposes a challenging problem for water resources managers. Since the water stored in snowpacks represents an important source of the water supply, a system which monitors and inventories the water equivalent of snow should clearly improve the water resources estimate. Recent results indicate that spaceborne microwave radiometry has the potential for inferring the snow depth and water equivalent information over large snow-covered areas. In order to assess this potential for determining the water equivalent of a snowpack, it is necessary to understand the microwave emission and scatter behavior of the snow at various wavelengths. The emitted microwave radiation is dependent on the physical temperature, crystal size, and density. The basic relationship between the properties of the snowpack and the emitted radiation may be derived by using the radiative transfer approach. Truck-mounted microwave instrumentation was used to study the microwave characteristics of the snowpack in the Colorado Rocky Mountain region in the vicinity of Fraser, Colorado during the winter of 1978. The spectral signatures of 5.0, 10.7, 18, and 37 GHz radiometers with dual polarization were used. These data compared favorably with calculated results based on recent microscopic scattering models.     

A novel neural network for the synthesis of antennas and microwave devices

A novel artificial neural network (SYNTHESIS-ANN) is presented, which has been designed for computationally intensive problems and applied to the optimization of antennas and microwave devices. The antenna example presented is optimized with respect to voltage standing-wave ratio, bandwidth, and frequency of operation. A simple microstrip transmission line problem is used to further describe the ANN effectiveness, in which microstrip line width is optimized with respect to line impedance. The ANNs exploit a unique number representation of input and output data in conjunction with a more standard neural network architecture. An ANN consisting of a heteroassociative memory provided a very efficient method of computing necessary geometrical values for the antenna when used in conjunction with a new randomization process. The number representation used provides significant insight into this new method of fault-tolerant computing. Further work is needed to evaluate the potential of this new paradigm.     

A topological method for determining the external symmetry number of molecules

A method for determining the external symmetry number of molecules and free radicals is described. The method of calculation is based on a topological approach, mainly by means of a factorized representation of molecules and free radicals. The input of formulae into the computer is achieved by a linear notation. The corresponding program is a part of a more important software dealing with the computation of thermochemical properties of molecules and free radicals in the gas phase.     

A method for calibrated maximum likelihood classification of forest types

A modification to the maximum likelihood algorithm was developed for classification of forest types in Sweden's part of the CORINE land cover mapping project. The new method, called the “calibrated maximum likelihood classification” involves an automated and iterative adjustment of prior weights until class frequency in the output corresponds to class frequency as calculated from objective (field-inventoried) estimates. This modification compensates for the maximum likelihood algorithm's tendency to over-represent dominant classes and under-represent less frequent ones. National forest inventory plot data measured from a five-year period are used to estimate relative frequency of class occurrence and to derive spectral signatures for each forest class. The classification method was implemented operationally within an automated production system which allowed rapid production of a country-wide forest type map from Landsat TM/ETM+ satellite data. The production system automated the retrieval and updating of forest inventory plots, a plot-to-image matching routine, illumination and haze correction of satellite imagery, and classification into forest classes using the calibrated maximum likelihood classification. This paper describes the details of the method and demonstrates the result of using an iterative adjustment of prior weights versus unadjusted prior weights. It shows that the calibrated maximum likelihood algorithm adjusts for the overclassification of classes that are well represented in the training data as well as for other classes, resulting in an output where class proportions are close to those as expected based on forest inventory data.