Application of Adaptive Divided Difference Filter on GPS/IMU Integrated Navigation System

The efficient and accurate approximate nonlinear filters have been widely used in the estimation of states and parameters of dynamical systems. In this paper, an adaptive divided difference filter is designed for precise estimation of states and parameters of micromechanical gyro navigation system. Based on the investigation of nonlinear divided difference filter the adaptive divided difference filter(ADDF) was designed, which takes account of the incorrect time-varying noise statistics of dynamical systems and compensation of the nonlinearity effects neglected by linearization. And its performance is superior to that of DDF and extended Kalman filter(EKF). Simulation results indicate that the advantages of the proposed nonlinear filters make them attractive alternatives to the extended Kalman filter.

Divide and recombine approach for warranty database: estimating the reliability of an automobile component

The continuously updated database of failures and censored data of numerous products has become large, and on some covariates, information regarding the failure times is missing in the database. As the dataset is large and has missing information, the analysis tasks become complicated and a long time is required to execute the programming codes. In such situations, the divide and recombine (D&R) approach, which has a practical computational performance for big data analysis, can be applied. In this study, the D&R approach was applied to analyze the real field data of an automobile component with incomplete information on covariates using the Weibull regression model. Model parameters were estimated using the expectation maximization algorithm. The results of the data analysis and simulation demonstrated that the D&R approach is applicable for analyzing such datasets. Further, the percentiles and reliability functions of the distribution under different covariate conditions were estimated to evaluate the component performance of these covariates. The findings of this study have managerial implications regarding design decisions, safety, and reliability of automobile components.

Analysis of Mobile and Internet Network Coverage: Propagation of Electromagnetic Waves and Concept of Digital Divide in Burundi

Mobile and Internet network coverage plays an important role in digital transformation and the exploitation of new services. The evolution of mobile networks from the first generation (1G) to the 5th generation is still a long process. 2G networks have developed the messaging service, which complements the already operational voice service. 2G technology has rapidly progressed to the third generation (3G), incorporating multimedia data transmission techniques. It then progressed to fourth generation (4G) and LTE (Long Term Evolution), increasing the transmission speed to improve 3G. Currently, developed countries have already moved to 5G. In developing countries, including Burundi, a member of the East African Community (ECA) where more than 80% are connected to 2G technologies, 40% are connected to the 3G network and 25% to the 4G network and are not yet connected to the 5G network and then still a process. The objective of this article is to analyze the coverage of 2G, 3G and 4G networks in Burundi. This analysis will make it possible to identify possible deficits in order to reduce the digital divide between connected urban areas and remote rural areas. Furthermore, this analysis will draw the attention of decision-makers to the need to deploy networks and coverage to allow the population to access mobile and Internet services and thus enable the digitalization of the population. Finally, this article shows the level of coverage, the digital divide and an overview of the deployment of base stations (BTS) throughout the country to promote the transformation and digital inclusion of services.

A Programmable 2.4GHz CMOS Multi-Modulus Frequency Divider

A programmable multi-modulus frequency divider is designed and implemented in a 0. 35μm CMOS process. The multi-modulus frequency divider is a single chip with two dividers in series,which are divided by 4 or 5 prescaler and by 128-255 multi-modulus frequency divider. In the circuit design, power and speed trade-offs are analyzed for the prescaler, and power optimization techniques are used according to the input frequency of each divider cell for the 128-255 multimodulus frequency divider. The chip is designed with ESD protected I/O PAD. The dividers chain can work as high as 2.4GHz with a single ended input signal and beyond 2.6GHz with differential input signals. The dual-modulus prescaler consumes 11mA of current while the 128-255 multi-modulus frequency divider consumes 17mA of current with a 3.3V power supply. The core area of the die without PAD is 0.65mm × 0.3mm. This programmable multi-modulus frequency divider can be used for 2.4GHz ISM band PLL-based frequency synthesizers. To our knowledge, this is the first reported multi-modulus frequency divider with this structure in China.

Integrated Low-Power CMOS VCO and Its Divide-by-2 Dividers

An integrated low power CMOS VCO and its divide by 2 dividers for WLAN transceivers are presented.The VCO is based on on chip symmetrical spiral inductor and differential diode and the divide by 2 dividers are based on the ILFD technique.Due to differential LC tanks and ILFD techniques,power consumption is low.The circuit is implemented in a 0 18μm CMOS process.Measurements show the proposed circuit could produce 3 6/1 8GHz dual band LO signals with a wide tuning range and low phase noise.1 8GHz LO signals are quadrature.It consumes 5mA at V DD =1 5V.The size of die area is only 1 0mm×1 0mm.

0.18μm CMOS programmable frequency divider design for DVB-T

The implementation of a programmable frequency divider, which is one of the components of the phase-locked loop （PLL） frequency synthesizer for digital video broadcastingterrestrial （DVB-T） and other modem communication systems, is presented. By cooperating with a dual-modulus prescaler, this divider can realize an integer frequency division from 926 to 1 387. Besides the traditional standard cell design flow, such as logic synthesis, placement and routing, the interactions between front-end and back-end are also considered to optimize the design flow under deep submicron technology. By back-annotating the back-end information to front-end design, a custom wire-load model is created which is more practical compared with the default model. This divider has been fabricated in TSMC 0. 18μm CMOS technology using Artisan standard cell library. The chip area is 675 μm × 475 μm and the power consumption is about 2 mW under a 1.8 V power supply. Measurement results show that it works correctly and can realize a frequency division with high precision.

An 8.5GHz 1∶8 Frequency Divider in 0.35μm CMOS Technology

An 1∶8 frequency divider is designed and realized in a 0 35μm standard CMOS technology.The chip consists of three stages of 1∶2 divider cells,which are constructed with source couple logic (SCL) flip flops.By revising the traditional topology of SCL flip flop,a divider with better performances is got.The results of measurement show that the whole chip achieves the frequency division at more than 8 5GHz.Each 1∶2 divider consumes about 11mW from a 3 3V supply.The divider can be used in RF and optic fiber transceivers and other high speed systems.

Bridging Digital Divide for English Learners at Chinese Secondary Schools

This article reviews the concept of digital divide and particularly discusses the digital divide among K-12 students in rural and urban China,as well as the e-learning strategies initiated by the Chinese government that were designed to minimize this digital divide in China.This article concludes by explaining the issue of skills on effective e-learning and correspondingly making suggestions for English teachers in K-12 schools in China.

Design of a Frequency Divider with Reduced Complexity Based on a Resonant Tunneling Diode

A novel edge-triggered D-flip-flop based on a resonant tunneling diode （RTD） is proposed and used to construct a binary frequency divider. The design is discussed in detail and the performance of the circuit is verified using SPICE. Relying on the nonlinear characteristics of RTD,we reduced the number of components used in our DFF circuit to only half of that required using conventional CMOS SCFL technology.

Design of 0.18 μm CMOS programmable frequency divider based on standard cells

The design of a programmable frequency divider, which is one of the components of the phase-locked loop （PLL） frequency synthesizer for transmitter and receiver in IEEE 802. 11 a standard, is investigated. The main steps in very large-scale integration （VLSI） design flow such as logic synthesis, floorplan and placement ＆ routing （P ＆ R） are introduced. By back-annotating the back-end information to the front-end design, the custom wire-load model is created and used for optimizing the design flow under deep submicron technology. The programmable frequency divider is implemented based on Artisan TSMC （Taiwan Semicoductor Manufacturing Co. Ltd. ）0. 18μm CMOS （complementary metal-oxide-semiconductor） standard cells and fabricated. The Chip area is 1 360. 5μm^2 and can work in the range of 100 to 200 MHz. The measurement results indicate that the design conforms to the frequency division precision.

The Art of Power Dividing:A Review for State-of-the-Art Planar Power Dividers

In this paper,massive state-of-theart planar power dividers are presented and discussed. The innovations of these superiorly-performanced power dividers lie in the performance breakthrough,physical configurations and function integrations. Eventually,based on the trend presented,the future of the power dividers is predicted. This paper might have inspiration significance to illuminate the way for the development of power dividers.

Simulation Optimization and Experimental Study of Cross-Wall Adiabatic Dividing Wall Column Used to Separate Hexane-Heptane-Octane System

Through separation of the hexane-heptane–octane system in a cross-wall adiabatic dividing wall column, the effects of feed position, side-draw position, liquid split ratio, vapor split ratio and their interactions on the energy consumption were analyzed by Aspen Plus under the constant product purity, and the response surface model for the energy consumption was regressed. Based on the restriction on the optimal operating zone, the comparison of different combinations of surrogate models and optimization methods showed that, the combination of the Kriging model and multi-island genetic algorithm(Kriging-MIGA) had better prediction ability than the combination of the response surface model and partial derivative method(RSM-PD), and RSM-PD had better optimization effect than Kriging-MIGA. With a self-made cross-wall adiabatic dividing wall column, the temperature at measuring points and the energy consumption were measured during experiments, the comparison between measured values and simulated ones demonstrated that the optimized values of variables searched by RSM-PD and Kriging-MIGA could be both used as the optimum technological conditions since the experimental reliability was ensured, with the optimum technological conditions shown below: The feed position is 6, the side-draw position is 7, the combinations of liquid split ratio and vapor split ratio are [0.14, 0.5] and [0.16, 0.52], respectively. RSM-PD and Kriging-MIGA can provide the appropriate optimization methods for the dividing wall column.

Use of Topographic Map Evidence to Test a Recently Proposed Regional Geomorphology Paradigm: Wind River-Sweetwater River Drainage Divide Area, Central Wyoming, USA

Topographic map evidence from the Wyoming Wind River-Sweetwater River drainage divide area is used to test a recently proposed regional geomorphology paradigm defined by massive south- and southeast-oriented continental ice sheet melt water floods that flowed across the entire Missouri River drainage basin. The new paradigm forces recognition of an ice sheet created and occupied deep “hole” and is fundamentally different from the commonly accepted paradigm in which a pre-glacial north- and northeast-oriented slope would have prevented continental ice sheet melt water from reaching or crossing the Wind River-Sweetwater River drainage divide. Divide crossings (or low points) are identified as places where water once flowed across the drainage divide. Map evidence is interpreted first from the accepted paradigm perspective and second from the new paradigm perspective to determine the simplest explanation. Both paradigm perspectives suggest south-oriented water crossed the drainage divide, although accepted paradigm interpretations do not satisfactorily explain the large number of observed divide crossings and are complicated by the need to bury the Owl Creek and Bridger Mountains to explain why the Wind River now flows in a north direction through Wind River Canyon. New paradigm interpretations explain the large number of divide crossings as diverging and converging channel evidence (as in flood-formed anastomosing channel complexes), Owl Creek and Bridger Mountain uplift to have occurred as south-oriented floodwaters carved Wind River Canyon, and a major flood flow reversal (caused by ice sheet related crustal warping and the opening up of deep “hole” space by ice sheet melting) as being responsible for the Wind River abrupt turn to the north. While this test only addresses topographic map evidence, Occam’s Razor suggests the new paradigm offers what in science should be the preferred Wind River-Sweetwater River drainage divide origin interpretations.

Origin of Little Missouri River - South Fork Grand River and nearby Drainage Divides in Harding County, South Dakota and Adjacent Eastern Montana, USA

Barbed tributaries flowing in southeast directions, an asymmetric drainage divide with both the South Fork Grand River and the North Fork Moreau River, and the Jump-off escarpment-surrounded basin (interpreted here to be a large abandoned headcut) are examples of topographic map evidence suggesting the north oriented Little Missouri River valley eroded headward across a large southeast oriented anastomosing complex of ice-marginal melt water flood flow channels that once crossed Harding County, South Dakota. Additional evidence includes southeast oriented tributaries to the northeast oriented South Fork Grand River and multiple divide crossings (e.g. through valleys and wind gaps) on the Boxelder Creek-Little Missouri River divide (in eastern Montana and west of the Little Missouri River) and suggests deep regional erosion occurred as the north oriented Little Missouri River valley eroded headward into and across the region. Harding County is located south and west of the southwest limit of coarse-grained glacial erratic material and ice-marginal melt water flow routes logically should have crossed it. Deep melt water erosion of Harding County and adjacent eastern Montana regions to the west is not consistent with many previous drainage history and glacial history interpretations, but is consistent with deep erosion by continental ice sheets.

A Low Power,High Sensitivity SiGe HBT Static Frequency Divider up to 90 GHz for Millimeter-Wave Application

A layout and connection optimization for static frequency divider is presented. The layout optimization provides a new circle topology transistors placement and reasonable connection structure, which reduces the parasitic effectively and enables self-oscillation frequency enhancement. Besides, bandwidth enhancement techniques based on a center-tap capacitor in input balun design and inductive peaking in latch design are adopted to improve further high frequency performance with low power consumption. As a proof of concept, design of a divide-by-2 static frequency divider in 0.13 μm SiGe BiCMOS technology is reported. With single-ended input clock signal, the divider is measured to be operated from 40 to 90 GHz. Phase noise measurements of a 90 GHz input clock signal indicate ideal behavior with no measurable noise contribution from the divider. The divider followed by a buffer that can deliver more than-10 dBm output power, which is sufficient to drive succeeding stage. To the author's knowledge, the divider exhibits a competitive power dissipation and the highest FOM among silicon based frequency dividers that operating higher than 70 GHz.

Numerical optimisation and experimental validation of divided rail freight brake disc crown

In this study, numerical optimisation and experimental validation of a divided rail freight brake disc crown made of grey cast iron EN-GJL-250 is presented.The analysed brake disc is used in rail freight wagons and possesses a load capacity of 22.5 tons per axle. Two of the divided rail freight brake discs are mounted on each axle.With the aid of numerical analysis, the thermal dissipation properties of the brake disc were optimised and ventilation losses were reduced, and the numerical results were compared with experimental results. A one-way fluid–structure interaction analysis was performed. A computational fluid dynamic model of a divided rail freight brake disc, used to predict air flow properties and heat convection, was incorporated into a finite element model of the disc and used to evaluate the temperature of the disc. A numerical parametrical optimisation of cooling ribs of the brake disc was also performed, and novel optimised cooling ribs were developed. A transient thermal numerical analysis of the brake disc was validated using temperature measurements obtained during a braking test on a test bench. The ventilation losses of the brake disc were measured on a test bench specifically designed for the task, and the losses were compared to the simulation results. The experimentally obtained ventilation losses and temperature measurements compared favourably with the simulation results, confirming that this type of simulation process may be confidently applied in the future. Through systematic optimisation of the divided rail freight brake disc, ventilation losses were reduced by 37% and the mass was reduced by 21%, resulting in better thermal performance that will bring with it substantial energy savings.

New sigma point filtering algorithms for nonlinear stochastic systems with correlated noises

New sigma point filtering algorithms, including the unscented Kalman filter （UKF） and the divided difference filter （DDF）, are designed to solve the nonlinear filtering problem under the condition of correlated noises. Based on the minimum mean square error estimation theory, the nonlinear optimal predictive and correction recursive formulas under the hypothesis that the input noise is correlated with the measurement noise are derived and can be described in a unified framework. Then, UKF and DDF with correlated noises are proposed on the basis of approximation of the posterior mean and covariance in the unified framework by using unscented transformation and second order Stirling＇s interpolation. The proposed UKF and DDF with correlated noises break through the limitation that input noise and measurement noise must be assumed to be uneorrelated in standard UKF and DDF. Two simulation examples show the effectiveness and feasibility of new algorithms for dealing with nonlinear filtering issue with correlated noises.

Modeling height–diameter relationship for Populus euphratica in the Tarim riparian forest ecosystem, Northwest China

Modeling height–diameter relationships is an important component in estimating and predicting forest development under different forest management scenarios. In this paper, ten widely used candidate height–diameter models were fitted to tree height and diameter at breast height（DBH）data for Populus euphratica Oliv. within a 100 ha permanent plots at Arghan Village in the lower reaches of the Tarim River, Xinjiang Uyghur Autonomous Region of China. Data from 4781 trees were used and split randomly into two sets：75 % of the data were used to estimate model parameters（model calibration）, and the remaining data（25 %） were reserved for model validation. All model performances were evaluated and compared by means of multiple model performance criteria such as asymptotic t-statistics of model parameters, standardized residuals against predicted height,root mean square error（RMSE）, Akaike’s informationcriterion（AIC）, mean prediction error（ME） and mean absolute error（MAE）. The estimated parameter a for model（6） was not statistically significant at a level of a = 0.05. RMSE and AIC test result for all models showed that exponential models（1）,（2）,（3） and（4） performed significantly better than others. All ten models had very small MEs and MAEs. Nearly all models underestimated tree heights except for model（6）. Comparing the MEs and MAEs of models, model（1） produced smaller MEs（0.0059） and MAEs（1.3754） than other models. To assess the predictive performance of models, we also calculated MEs by dividing the model validation data set into 10-cm DBH classes. This suggested that all models were likely to create higher mean prediction errors for tree DBH classes[20 cm. However, no clear trend was found among models.Model（6） generated significantly smaller mean prediction errors across all tree DBH classes. Considering all the aforementioned criteria, model（1）： TH ？ 1：3 t a= e1 t b？eàc？DBHT and model（6）： TH ？ 1：3 t DBH2= ea t b？DBH t c ？ DBH2T are recommended as suitable models for describing the height–diameter relationship of P. euphratica. The limitations of other models showing poor performance in predicting tree height are discussed. We provide explanations for these shortcomings.

A power divider based on a new kind of composite right/left-handed transmission line (CRLH TL) unit

A new power divider, composed of a novel composite right/left-handed (CRLH) transmission line (TL) unit, is proposed. The properties of the power divider based on four CRLH TL unit cells are investigated theoretically. By adjusting the parameters of the capacitors and the inductors, the power divider shows perfectly symmetric power division at 5.13 GHz, return loss up to ?24 dB, with the transmitted power being close to ?3.1 dB. The phenomena are demonstrated by simulation results. Being compact in size and low-cost, the proposed power divider is very suitable for microwave and millimeter wave integrated circuits.

Compact UWB Power Divider, Analysis and Design

In this paper, two ultra-wide band power dividers are introduced. Compact equal power divider is considered firstly where an extended transmission lines and double open stubs are used in order to increase the bandwidth. Secondly, an unequal UWB power divider is introduced where multi-stage impedance is used. The proposed power dividers are fabricated and measured. The overall sizes of the proposed power dividers are 11.37 × 17.87 mm2 for the equal one and 12.13 × 29.03 mm2 for the unequal power divider. The simulated results are compared with the measured results and good agreement is obtained.